Source file src/cmd/compile/internal/ssagen/ssa.go

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package ssagen
     6  
     7  import (
     8  	"bufio"
     9  	"bytes"
    10  	"cmp"
    11  	"fmt"
    12  	"go/constant"
    13  	"html"
    14  	"internal/buildcfg"
    15  	"internal/goexperiment"
    16  	"internal/runtime/gc"
    17  	"os"
    18  	"path/filepath"
    19  	"slices"
    20  	"strings"
    21  
    22  	"cmd/compile/internal/abi"
    23  	"cmd/compile/internal/base"
    24  	"cmd/compile/internal/ir"
    25  	"cmd/compile/internal/liveness"
    26  	"cmd/compile/internal/objw"
    27  	"cmd/compile/internal/reflectdata"
    28  	"cmd/compile/internal/rttype"
    29  	"cmd/compile/internal/ssa"
    30  	"cmd/compile/internal/ssa/block"
    31  	"cmd/compile/internal/ssa/ssaconfig"
    32  	"cmd/compile/internal/ssa/ssadebug"
    33  	"cmd/compile/internal/ssa/ssahtml"
    34  	"cmd/compile/internal/ssa/ssaop"
    35  	"cmd/compile/internal/staticdata"
    36  	"cmd/compile/internal/typecheck"
    37  	"cmd/compile/internal/types"
    38  	"cmd/internal/obj"
    39  	"cmd/internal/objabi"
    40  	"cmd/internal/src"
    41  	"cmd/internal/sys"
    42  
    43  	rtabi "internal/abi"
    44  )
    45  
    46  var ssaConfig *ssa.Config
    47  var ssaCaches []ssa.Cache
    48  
    49  var ssaDump string     // early copy of $GOSSAFUNC; the func name to dump output for
    50  var ssaDir string      // optional destination for ssa dump file
    51  var ssaDumpStdout bool // whether to dump to stdout
    52  var ssaDumpCFG string  // generate CFGs for these phases
    53  const ssaDumpFile = "ssa.html"
    54  
    55  // ssaDumpInlined holds all inlined functions when ssaDump contains a function name.
    56  var ssaDumpInlined []*ir.Func
    57  
    58  // Maximum size we will aggregate heap allocations of scalar locals.
    59  // Almost certainly can't hurt to be as big as the tiny allocator.
    60  // Might help to be a bit bigger.
    61  const maxAggregatedHeapAllocation = 16
    62  
    63  func DumpInline(fn *ir.Func) {
    64  	if ssaDump != "" && ssaDump == ir.FuncName(fn) {
    65  		ssaDumpInlined = append(ssaDumpInlined, fn)
    66  	}
    67  }
    68  
    69  func InitEnv() {
    70  	ssaDump = os.Getenv("GOSSAFUNC")
    71  	if ssaDump == "" {
    72  		ssaDump = base.Debug.Html
    73  	}
    74  	ssaDir = os.Getenv("GOSSADIR")
    75  	if ssaDump != "" {
    76  		if strings.HasSuffix(ssaDump, "+") {
    77  			ssaDump = ssaDump[:len(ssaDump)-1]
    78  			ssaDumpStdout = true
    79  		}
    80  		spl := strings.Split(ssaDump, ":")
    81  		if len(spl) > 1 {
    82  			ssaDump = spl[0]
    83  			ssaDumpCFG = spl[1]
    84  		}
    85  	}
    86  }
    87  
    88  func InitConfig(config *ssa.Config) {
    89  	ssaConfig = config
    90  
    91  	if Arch.SoftFloat {
    92  		softfloatInit()
    93  	}
    94  
    95  	// Generate a few pointer types that are uncommon in the frontend but common in the backend.
    96  	// Caching is disabled in the backend, so generating these here avoids allocations.
    97  	_ = types.NewPtr(types.Types[types.TINTER])                             // *interface{}
    98  	_ = types.NewPtr(types.NewPtr(types.Types[types.TSTRING]))              // **string
    99  	_ = types.NewPtr(types.NewSlice(types.Types[types.TINTER]))             // *[]interface{}
   100  	_ = types.NewPtr(types.NewPtr(types.ByteType))                          // **byte
   101  	_ = types.NewPtr(types.NewSlice(types.ByteType))                        // *[]byte
   102  	_ = types.NewPtr(types.NewSlice(types.Types[types.TSTRING]))            // *[]string
   103  	_ = types.NewPtr(types.NewPtr(types.NewPtr(types.Types[types.TUINT8]))) // ***uint8
   104  	_ = types.NewPtr(types.Types[types.TINT16])                             // *int16
   105  	_ = types.NewPtr(types.Types[types.TINT64])                             // *int64
   106  	_ = types.NewPtr(types.ErrorType)                                       // *error
   107  	_ = types.NewPtr(reflectdata.MapType())                                 // *internal/runtime/maps.Map
   108  	_ = types.NewPtr(deferstruct())                                         // *runtime._defer
   109  	types.NewPtrCacheEnabled = false
   110  
   111  	ssaConfig.Race = base.Flag.Race
   112  	ssaCaches = make([]ssa.Cache, base.Flag.LowerC)
   113  
   114  	// Set up some runtime functions we'll need to call.
   115  	ir.Syms.AssertE2I = typecheck.LookupRuntimeFunc("assertE2I")
   116  	ir.Syms.AssertE2I2 = typecheck.LookupRuntimeFunc("assertE2I2")
   117  	ir.Syms.CgoCheckMemmove = typecheck.LookupRuntimeFunc("cgoCheckMemmove")
   118  	ir.Syms.CgoCheckPtrWrite = typecheck.LookupRuntimeFunc("cgoCheckPtrWrite")
   119  	ir.Syms.CheckPtrAlignment = typecheck.LookupRuntimeFunc("checkptrAlignment")
   120  	ir.Syms.Deferproc = typecheck.LookupRuntimeFunc("deferproc")
   121  	ir.Syms.Deferprocat = typecheck.LookupRuntimeFunc("deferprocat")
   122  	ir.Syms.DeferprocStack = typecheck.LookupRuntimeFunc("deferprocStack")
   123  	ir.Syms.Deferreturn = typecheck.LookupRuntimeFunc("deferreturn")
   124  	ir.Syms.Duffcopy = typecheck.LookupRuntimeFunc("duffcopy")
   125  	ir.Syms.Duffzero = typecheck.LookupRuntimeFunc("duffzero")
   126  	ir.Syms.GCWriteBarrier[0] = typecheck.LookupRuntimeFunc("gcWriteBarrier1")
   127  	ir.Syms.GCWriteBarrier[1] = typecheck.LookupRuntimeFunc("gcWriteBarrier2")
   128  	ir.Syms.GCWriteBarrier[2] = typecheck.LookupRuntimeFunc("gcWriteBarrier3")
   129  	ir.Syms.GCWriteBarrier[3] = typecheck.LookupRuntimeFunc("gcWriteBarrier4")
   130  	ir.Syms.GCWriteBarrier[4] = typecheck.LookupRuntimeFunc("gcWriteBarrier5")
   131  	ir.Syms.GCWriteBarrier[5] = typecheck.LookupRuntimeFunc("gcWriteBarrier6")
   132  	ir.Syms.GCWriteBarrier[6] = typecheck.LookupRuntimeFunc("gcWriteBarrier7")
   133  	ir.Syms.GCWriteBarrier[7] = typecheck.LookupRuntimeFunc("gcWriteBarrier8")
   134  	ir.Syms.Goschedguarded = typecheck.LookupRuntimeFunc("goschedguarded")
   135  	ir.Syms.Growslice = typecheck.LookupRuntimeFunc("growslice")
   136  	ir.Syms.GrowsliceBuf = typecheck.LookupRuntimeFunc("growsliceBuf")
   137  	ir.Syms.GrowsliceBufNoAlias = typecheck.LookupRuntimeFunc("growsliceBufNoAlias")
   138  	ir.Syms.GrowsliceNoAlias = typecheck.LookupRuntimeFunc("growsliceNoAlias")
   139  	ir.Syms.MoveSlice = typecheck.LookupRuntimeFunc("moveSlice")
   140  	ir.Syms.MoveSliceNoScan = typecheck.LookupRuntimeFunc("moveSliceNoScan")
   141  	ir.Syms.MoveSliceNoCap = typecheck.LookupRuntimeFunc("moveSliceNoCap")
   142  	ir.Syms.MoveSliceNoCapNoScan = typecheck.LookupRuntimeFunc("moveSliceNoCapNoScan")
   143  	ir.Syms.InterfaceSwitch = typecheck.LookupRuntimeFunc("interfaceSwitch")
   144  	for i := 1; i < len(ir.Syms.MallocGCSmallNoScan); i++ {
   145  		ir.Syms.MallocGCSmallNoScan[i] = typecheck.LookupRuntimeFunc(fmt.Sprintf("mallocgcSmallNoScanSC%d", i))
   146  	}
   147  	for i := 1; i < len(ir.Syms.MallocGCSmallScanNoHeader); i++ {
   148  		ir.Syms.MallocGCSmallScanNoHeader[i] = typecheck.LookupRuntimeFunc(fmt.Sprintf("mallocgcSmallScanNoHeaderSC%d", i))
   149  	}
   150  	ir.Syms.MallocGCTiny = typecheck.LookupRuntimeFunc("mallocgcTinySC2")
   151  	ir.Syms.MallocGC = typecheck.LookupRuntimeFunc("mallocgc")
   152  	ir.Syms.Memmove = typecheck.LookupRuntimeFunc("memmove")
   153  	ir.Syms.Memequal = typecheck.LookupRuntimeFunc("memequal")
   154  	ir.Syms.Msanread = typecheck.LookupRuntimeFunc("msanread")
   155  	ir.Syms.Msanwrite = typecheck.LookupRuntimeFunc("msanwrite")
   156  	ir.Syms.Msanmove = typecheck.LookupRuntimeFunc("msanmove")
   157  	ir.Syms.Asanread = typecheck.LookupRuntimeFunc("asanread")
   158  	ir.Syms.Asanwrite = typecheck.LookupRuntimeFunc("asanwrite")
   159  	ir.Syms.Newobject = typecheck.LookupRuntimeFunc("newobject")
   160  	ir.Syms.Newproc = typecheck.LookupRuntimeFunc("newproc")
   161  	ir.Syms.PanicBounds = typecheck.LookupRuntimeFunc("panicBounds")
   162  	ir.Syms.PanicExtend = typecheck.LookupRuntimeFunc("panicExtend")
   163  	ir.Syms.Panicdivide = typecheck.LookupRuntimeFunc("panicdivide")
   164  	ir.Syms.PanicdottypeE = typecheck.LookupRuntimeFunc("panicdottypeE")
   165  	ir.Syms.PanicdottypeI = typecheck.LookupRuntimeFunc("panicdottypeI")
   166  	ir.Syms.Panicnildottype = typecheck.LookupRuntimeFunc("panicnildottype")
   167  	ir.Syms.Panicoverflow = typecheck.LookupRuntimeFunc("panicoverflow")
   168  	ir.Syms.Panicshift = typecheck.LookupRuntimeFunc("panicshift")
   169  	ir.Syms.PanicSimdImm = typecheck.LookupRuntimeFunc("panicSimdImm")
   170  	ir.Syms.Racefuncenter = typecheck.LookupRuntimeFunc("racefuncenter")
   171  	ir.Syms.Racefuncexit = typecheck.LookupRuntimeFunc("racefuncexit")
   172  	ir.Syms.Raceread = typecheck.LookupRuntimeFunc("raceread")
   173  	ir.Syms.Racereadrange = typecheck.LookupRuntimeFunc("racereadrange")
   174  	ir.Syms.Racewrite = typecheck.LookupRuntimeFunc("racewrite")
   175  	ir.Syms.Racewriterange = typecheck.LookupRuntimeFunc("racewriterange")
   176  	ir.Syms.TypeAssert = typecheck.LookupRuntimeFunc("typeAssert")
   177  	ir.Syms.WBZero = typecheck.LookupRuntimeFunc("wbZero")
   178  	ir.Syms.WBMove = typecheck.LookupRuntimeFunc("wbMove")
   179  	ir.Syms.X86HasAVX = typecheck.LookupRuntimeVar("x86HasAVX")                       // bool
   180  	ir.Syms.X86HasFMA = typecheck.LookupRuntimeVar("x86HasFMA")                       // bool
   181  	ir.Syms.X86HasPOPCNT = typecheck.LookupRuntimeVar("x86HasPOPCNT")                 // bool
   182  	ir.Syms.X86HasSSE41 = typecheck.LookupRuntimeVar("x86HasSSE41")                   // bool
   183  	ir.Syms.ARMHasVFPv4 = typecheck.LookupRuntimeVar("armHasVFPv4")                   // bool
   184  	ir.Syms.ARM64HasATOMICS = typecheck.LookupRuntimeVar("arm64HasATOMICS")           // bool
   185  	ir.Syms.Loong64HasLAMCAS = typecheck.LookupRuntimeVar("loong64HasLAMCAS")         // bool
   186  	ir.Syms.Loong64HasLAM_BH = typecheck.LookupRuntimeVar("loong64HasLAM_BH")         // bool
   187  	ir.Syms.Loong64HasDBAR_HINTS = typecheck.LookupRuntimeVar("loong64HasDBAR_HINTS") // bool
   188  	ir.Syms.Loong64HasLSX = typecheck.LookupRuntimeVar("loong64HasLSX")               // bool
   189  	ir.Syms.RISCV64HasZbb = typecheck.LookupRuntimeVar("riscv64HasZbb")               // bool
   190  	ir.Syms.Staticuint64s = typecheck.LookupRuntimeVar("staticuint64s")
   191  	ir.Syms.Typedmemmove = typecheck.LookupRuntimeFunc("typedmemmove")
   192  	ir.Syms.Udiv = typecheck.LookupRuntimeVar("udiv")                 // asm func with special ABI
   193  	ir.Syms.WriteBarrier = typecheck.LookupRuntimeVar("writeBarrier") // struct { bool; ... }
   194  	ir.Syms.Zerobase = typecheck.LookupRuntimeVar("zerobase")
   195  	ir.Syms.ZeroVal = typecheck.LookupRuntimeVar("zeroVal")
   196  
   197  	if Arch.LinkArch.Family == sys.Wasm {
   198  		BoundsCheckFunc[ssa.BoundsIndex] = typecheck.LookupRuntimeFunc("goPanicIndex")
   199  		BoundsCheckFunc[ssa.BoundsIndexU] = typecheck.LookupRuntimeFunc("goPanicIndexU")
   200  		BoundsCheckFunc[ssa.BoundsSliceAlen] = typecheck.LookupRuntimeFunc("goPanicSliceAlen")
   201  		BoundsCheckFunc[ssa.BoundsSliceAlenU] = typecheck.LookupRuntimeFunc("goPanicSliceAlenU")
   202  		BoundsCheckFunc[ssa.BoundsSliceAcap] = typecheck.LookupRuntimeFunc("goPanicSliceAcap")
   203  		BoundsCheckFunc[ssa.BoundsSliceAcapU] = typecheck.LookupRuntimeFunc("goPanicSliceAcapU")
   204  		BoundsCheckFunc[ssa.BoundsSliceB] = typecheck.LookupRuntimeFunc("goPanicSliceB")
   205  		BoundsCheckFunc[ssa.BoundsSliceBU] = typecheck.LookupRuntimeFunc("goPanicSliceBU")
   206  		BoundsCheckFunc[ssa.BoundsSlice3Alen] = typecheck.LookupRuntimeFunc("goPanicSlice3Alen")
   207  		BoundsCheckFunc[ssa.BoundsSlice3AlenU] = typecheck.LookupRuntimeFunc("goPanicSlice3AlenU")
   208  		BoundsCheckFunc[ssa.BoundsSlice3Acap] = typecheck.LookupRuntimeFunc("goPanicSlice3Acap")
   209  		BoundsCheckFunc[ssa.BoundsSlice3AcapU] = typecheck.LookupRuntimeFunc("goPanicSlice3AcapU")
   210  		BoundsCheckFunc[ssa.BoundsSlice3B] = typecheck.LookupRuntimeFunc("goPanicSlice3B")
   211  		BoundsCheckFunc[ssa.BoundsSlice3BU] = typecheck.LookupRuntimeFunc("goPanicSlice3BU")
   212  		BoundsCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeFunc("goPanicSlice3C")
   213  		BoundsCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeFunc("goPanicSlice3CU")
   214  		BoundsCheckFunc[ssa.BoundsConvert] = typecheck.LookupRuntimeFunc("goPanicSliceConvert")
   215  	}
   216  
   217  	// Wasm (all asm funcs with special ABIs)
   218  	ir.Syms.WasmDiv = typecheck.LookupRuntimeVar("wasmDiv")
   219  	ir.Syms.WasmTruncS = typecheck.LookupRuntimeVar("wasmTruncS")
   220  	ir.Syms.WasmTruncU = typecheck.LookupRuntimeVar("wasmTruncU")
   221  	ir.Syms.SigPanic = typecheck.LookupRuntimeFunc("sigpanic")
   222  }
   223  
   224  func InitTables() {
   225  	initIntrinsics(nil)
   226  }
   227  
   228  // AbiForBodylessFuncStackMap returns the ABI for a bodyless function's stack map.
   229  // This is not necessarily the ABI used to call it.
   230  // Currently (1.17 dev) such a stack map is always ABI0;
   231  // any ABI wrapper that is present is nosplit, hence a precise
   232  // stack map is not needed there (the parameters survive only long
   233  // enough to call the wrapped assembly function).
   234  func AbiForBodylessFuncStackMap(fn *ir.Func) *abi.ABIConfig {
   235  	return ssaConfig.ABI0
   236  }
   237  
   238  // abiForFunc implements ABI policy for a function.
   239  // Passing a nil function returns the default ABI based on experiment configuration.
   240  func abiForFunc(fn *ir.Func, abi0, abi1 *abi.ABIConfig) *abi.ABIConfig {
   241  	if buildcfg.Experiment.RegabiArgs {
   242  		// Select the ABI based on the function's defining ABI.
   243  		if fn == nil {
   244  			return abi1
   245  		}
   246  		switch fn.ABI {
   247  		case obj.ABI0:
   248  			return abi0
   249  		case obj.ABIInternal:
   250  			// TODO(austin): Clean up the nomenclature here.
   251  			// It's not clear that "abi1" is ABIInternal.
   252  			return abi1
   253  		}
   254  		base.Fatalf("function %v has unknown ABI %v", fn, fn.ABI)
   255  		panic("not reachable")
   256  	}
   257  
   258  	a := abi0
   259  	if fn != nil {
   260  		if fn.Pragma&ir.RegisterParams != 0 { // TODO(register args) remove after register abi is working
   261  			a = abi1
   262  		}
   263  	}
   264  	return a
   265  }
   266  
   267  // emitOpenDeferInfo emits FUNCDATA information about the defers in a function
   268  // that is using open-coded defers.  This funcdata is used to determine the active
   269  // defers in a function and execute those defers during panic processing.
   270  //
   271  // The funcdata is all encoded in varints (since values will almost always be less than
   272  // 128, but stack offsets could potentially be up to 2Gbyte). All "locations" (offsets)
   273  // for stack variables are specified as the number of bytes below varp (pointer to the
   274  // top of the local variables) for their starting address. The format is:
   275  //
   276  //   - Offset of the deferBits variable
   277  //   - Offset of the first closure slot (the rest are laid out consecutively).
   278  func (s *state) emitOpenDeferInfo() {
   279  	firstOffset := s.openDefers[0].closureNode.FrameOffset()
   280  
   281  	// Verify that cmpstackvarlt laid out the slots in order.
   282  	for i, r := range s.openDefers {
   283  		have := r.closureNode.FrameOffset()
   284  		want := firstOffset + int64(i)*int64(types.PtrSize)
   285  		if have != want {
   286  			base.FatalfAt(s.curfn.Pos(), "unexpected frame offset for open-coded defer slot #%v: have %v, want %v", i, have, want)
   287  		}
   288  	}
   289  
   290  	x := base.Ctxt.Lookup(s.curfn.LSym.Name + ".opendefer")
   291  	x.Set(obj.AttrContentAddressable, true)
   292  	x.Align = 1
   293  	s.curfn.LSym.Func().OpenCodedDeferInfo = x
   294  
   295  	off := 0
   296  	off = objw.Uvarint(x, off, uint64(-s.deferBitsTemp.FrameOffset()))
   297  	off = objw.Uvarint(x, off, uint64(-firstOffset))
   298  }
   299  
   300  // buildssa builds an SSA function for fn.
   301  // worker indicates which of the backend workers is doing the processing.
   302  func buildssa(compiler ssa.Compiler, fn *ir.Func, worker int, isPgoHot bool) (*ssa.Func, ssa.HTMLWriter) {
   303  	name := ir.FuncName(fn)
   304  
   305  	abiSelf := abiForFunc(fn, ssaConfig.ABI0, ssaConfig.ABI1)
   306  
   307  	printssa := false
   308  	// match either a simple name e.g. "(*Reader).Reset", package.name e.g. "compress/gzip.(*Reader).Reset", or subpackage name "gzip.(*Reader).Reset"
   309  	// optionally allows an ABI suffix specification in the GOSSAHASH, e.g. "(*Reader).Reset<0>" etc
   310  	if strings.Contains(ssaDump, name) { // in all the cases the function name is entirely contained within the GOSSAFUNC string.
   311  		nameOptABI := name
   312  		if l := len(ssaDump); l > 1 && ssaDump[l-2] == ',' { // ABI specification
   313  			nameOptABI = ssa.FuncNameABI(name, abiSelf.Which())
   314  		} else if strings.HasSuffix(ssaDump, ">") { // if they use the linker syntax instead....
   315  			l := len(ssaDump)
   316  			if l >= 3 && ssaDump[l-3] == '<' {
   317  				nameOptABI = ssa.FuncNameABI(name, abiSelf.Which())
   318  				ssaDump = ssaDump[:l-3] + "," + ssaDump[l-2:l-1]
   319  			}
   320  		}
   321  		pkgDotName := base.Ctxt.Pkgpath + "." + nameOptABI
   322  		printssa = nameOptABI == ssaDump || // "(*Reader).Reset"
   323  			pkgDotName == ssaDump || // "compress/gzip.(*Reader).Reset"
   324  			strings.HasSuffix(pkgDotName, ssaDump) && strings.HasSuffix(pkgDotName, "/"+ssaDump) // "gzip.(*Reader).Reset"
   325  	}
   326  
   327  	var astBuf *bytes.Buffer
   328  	if printssa {
   329  		astBuf = &bytes.Buffer{}
   330  		ir.FDumpList(astBuf, "buildssa-body", fn.Body)
   331  		if ssaDumpStdout {
   332  			fmt.Println("generating SSA for", name)
   333  			fmt.Print(astBuf.String())
   334  		}
   335  	}
   336  
   337  	var s state
   338  	s.pushLine(fn.Pos())
   339  	defer s.popLine()
   340  
   341  	s.hasdefer = fn.HasDefer()
   342  	if fn.Pragma&ir.CgoUnsafeArgs != 0 {
   343  		s.cgoUnsafeArgs = true
   344  	}
   345  	s.checkPtrEnabled = ir.ShouldCheckPtr(fn, 1)
   346  
   347  	if base.Flag.Cfg.Instrumenting && fn.Pragma&ir.Norace == 0 && !fn.Linksym().ABIWrapper() {
   348  		if !base.Flag.Race || !objabi.LookupPkgSpecial(fn.Sym().Pkg.Path).NoRaceFunc {
   349  			s.instrumentMemory = true
   350  			if base.Flag.Race {
   351  				s.instrumentEnterExit = true
   352  			}
   353  		}
   354  	}
   355  
   356  	fe := ssafn{
   357  		curfn: fn,
   358  		log:   printssa && ssaDumpStdout,
   359  	}
   360  	s.curfn = fn
   361  
   362  	cache := &ssaCaches[worker]
   363  	cache.Reset()
   364  
   365  	s.f = ssaConfig.NewFunc(&fe, cache)
   366  	s.config = ssaConfig
   367  	s.f.Type = fn.Type()
   368  	s.f.Name = name
   369  	s.f.PrintOrHtmlSSA = printssa
   370  	if fn.Pragma&ir.Nosplit != 0 {
   371  		s.f.NoSplit = true
   372  	}
   373  	s.f.ABI0 = ssaConfig.ABI0
   374  	s.f.ABI1 = ssaConfig.ABI1
   375  	s.f.ABIDefault = abiForFunc(nil, ssaConfig.ABI0, ssaConfig.ABI1)
   376  	s.f.ABISelf = abiSelf
   377  
   378  	s.panics = map[funcLine]*ssa.Block{}
   379  	s.softFloat = s.config.SoftFloat
   380  
   381  	// Allocate starting block
   382  	s.f.Entry = s.f.NewBlock(block.BlockPlain)
   383  	s.f.Entry.Pos = fn.Pos()
   384  	s.f.IsPgoHot = isPgoHot
   385  	var htmlWriter *ssahtml.HTMLWriter
   386  
   387  	if printssa {
   388  		ssaDF := ssaDumpFile
   389  		if ssaDir != "" {
   390  			ssaDF = filepath.Join(ssaDir, base.Ctxt.Pkgpath+"."+s.f.NameABI()+".html")
   391  			ssaD := filepath.Dir(ssaDF)
   392  			os.MkdirAll(ssaD, 0755)
   393  		}
   394  		htmlWriter = ssahtml.NewHTMLWriter(ssaDF, s.f, ssaDumpCFG, compiler.Passes())
   395  		// TODO: generate and print a mapping from nodes to values and blocks
   396  		dumpSourcesColumn(htmlWriter, fn)
   397  		htmlWriter.WriteAST("AST", astBuf)
   398  		s.f.FatalCleanup = htmlWriter.FatalCleanup
   399  	}
   400  
   401  	// Allocate starting values
   402  	s.labels = map[string]*ssaLabel{}
   403  	s.fwdVars = map[ir.Node]*ssa.Value{}
   404  	s.startmem = s.entryNewValue0(ssaop.OpInitMem, types.TypeMem)
   405  
   406  	s.hasOpenDefers = base.Flag.N == 0 && s.hasdefer && !s.curfn.OpenCodedDeferDisallowed()
   407  	switch {
   408  	case base.Debug.NoOpenDefer != 0:
   409  		s.hasOpenDefers = false
   410  	case s.hasOpenDefers && (base.Ctxt.Flag_shared || base.Ctxt.Flag_dynlink) && base.Ctxt.Arch.Name == "386":
   411  		// Don't support open-coded defers for 386 ONLY when using shared
   412  		// libraries, because there is extra code (added by rewriteToUseGot())
   413  		// preceding the deferreturn/ret code that we don't track correctly.
   414  		//
   415  		// TODO this restriction can be removed given adjusted offset in computeDeferReturn in cmd/link/internal/ld/pcln.go
   416  		s.hasOpenDefers = false
   417  	}
   418  	if s.hasOpenDefers && s.instrumentEnterExit {
   419  		// Skip doing open defers if we need to instrument function
   420  		// returns for the race detector, since we will not generate that
   421  		// code in the case of the extra deferreturn/ret segment.
   422  		s.hasOpenDefers = false
   423  	}
   424  	if s.hasOpenDefers {
   425  		// Similarly, skip if there are any heap-allocated result
   426  		// parameters that need to be copied back to their stack slots.
   427  		for _, f := range s.curfn.Type().Results() {
   428  			if !f.Nname.(*ir.Name).OnStack() {
   429  				s.hasOpenDefers = false
   430  				break
   431  			}
   432  		}
   433  	}
   434  	if s.hasOpenDefers &&
   435  		s.curfn.NumReturns*s.curfn.NumDefers > 15 {
   436  		// Since we are generating defer calls at every exit for
   437  		// open-coded defers, skip doing open-coded defers if there are
   438  		// too many returns (especially if there are multiple defers).
   439  		// Open-coded defers are most important for improving performance
   440  		// for smaller functions (which don't have many returns).
   441  		s.hasOpenDefers = false
   442  	}
   443  
   444  	s.sp = s.entryNewValue0(ssaop.OpSP, types.Types[types.TUINTPTR]) // TODO: use generic pointer type (unsafe.Pointer?) instead
   445  	s.sb = s.entryNewValue0(ssaop.OpSB, types.Types[types.TUINTPTR])
   446  
   447  	s.startBlock(s.f.Entry)
   448  	s.vars[memVar] = s.startmem
   449  	if s.hasOpenDefers {
   450  		// Create the deferBits variable and stack slot.  deferBits is a
   451  		// bitmask showing which of the open-coded defers in this function
   452  		// have been activated.
   453  		deferBitsTemp := typecheck.TempAt(src.NoXPos, s.curfn, types.Types[types.TUINT8])
   454  		deferBitsTemp.SetAddrtaken(true)
   455  		s.deferBitsTemp = deferBitsTemp
   456  		// For this value, AuxInt is initialized to zero by default
   457  		startDeferBits := s.entryNewValue0(ssaop.OpConst8, types.Types[types.TUINT8])
   458  		s.vars[deferBitsVar] = startDeferBits
   459  		s.deferBitsAddr = s.addr(deferBitsTemp)
   460  		s.store(types.Types[types.TUINT8], s.deferBitsAddr, startDeferBits)
   461  		// Make sure that the deferBits stack slot is kept alive (for use
   462  		// by panics) and stores to deferBits are not eliminated, even if
   463  		// all checking code on deferBits in the function exit can be
   464  		// eliminated, because the defer statements were all
   465  		// unconditional.
   466  		s.vars[memVar] = s.newValue1Apos(ssaop.OpVarLive, types.TypeMem, deferBitsTemp, s.mem(), false)
   467  	}
   468  
   469  	var params *abi.ABIParamResultInfo
   470  	params = s.f.ABISelf.ABIAnalyze(fn.Type(), true)
   471  
   472  	// The backend's stackframe pass prunes away entries from the fn's
   473  	// Dcl list, including PARAMOUT nodes that correspond to output
   474  	// params passed in registers. Walk the Dcl list and capture these
   475  	// nodes to a side list, so that we'll have them available during
   476  	// DWARF-gen later on. See issue 48573 for more details.
   477  	var debugInfo ssadebug.FuncDebug
   478  	for _, n := range fn.Dcl {
   479  		if n.Class == ir.PPARAMOUT && n.IsOutputParamInRegisters() {
   480  			debugInfo.RegOutputParams = append(debugInfo.RegOutputParams, n)
   481  		}
   482  	}
   483  	fn.DebugInfo = &debugInfo
   484  
   485  	// Generate addresses of local declarations
   486  	s.decladdrs = map[*ir.Name]*ssa.Value{}
   487  	for _, n := range fn.Dcl {
   488  		switch n.Class {
   489  		case ir.PPARAM:
   490  			// Be aware that blank and unnamed input parameters will not appear here, but do appear in the type
   491  			s.decladdrs[n] = s.entryNewValue2A(ssaop.OpLocalAddr, types.NewPtr(n.Type()), n, s.sp, s.startmem)
   492  		case ir.PPARAMOUT:
   493  			s.decladdrs[n] = s.entryNewValue2A(ssaop.OpLocalAddr, types.NewPtr(n.Type()), n, s.sp, s.startmem)
   494  		case ir.PAUTO:
   495  			// processed at each use, to prevent Addr coming
   496  			// before the decl.
   497  		default:
   498  			s.Fatalf("local variable with class %v unimplemented", n.Class)
   499  		}
   500  	}
   501  
   502  	s.f.OwnAux = ssa.OwnAuxCall(fn.LSym, params)
   503  
   504  	// Populate SSAable arguments.
   505  	for _, n := range fn.Dcl {
   506  		if n.Class == ir.PPARAM {
   507  			if s.canSSA(n) {
   508  				v := s.newValue0A(ssaop.OpArg, n.Type(), n)
   509  				s.vars[n] = v
   510  				s.addNamedValue(n, v) // This helps with debugging information, not needed for compilation itself.
   511  			} else { // address was taken AND/OR too large for SSA
   512  				paramAssignment := ssa.ParamAssignmentForArgName(s.f, n)
   513  				if len(paramAssignment.Registers) > 0 {
   514  					if ssa.CanSSA(n.Type()) { // SSA-able type, so address was taken -- receive value in OpArg, DO NOT bind to var, store immediately to memory.
   515  						v := s.newValue0A(ssaop.OpArg, n.Type(), n)
   516  						s.store(n.Type(), s.decladdrs[n], v)
   517  					} else { // Too big for SSA.
   518  						// Brute force, and early, do a bunch of stores from registers
   519  						// Note that expand calls knows about this and doesn't trouble itself with larger-than-SSA-able Args in registers.
   520  						s.storeParameterRegsToStack(s.f.ABISelf, paramAssignment, n, s.decladdrs[n], false)
   521  					}
   522  				}
   523  			}
   524  		}
   525  	}
   526  
   527  	// Populate closure variables.
   528  	if fn.Needctxt() {
   529  		clo := s.entryNewValue0(ssaop.OpGetClosurePtr, s.f.Config.Types.BytePtr)
   530  		if fn.RangeParent != nil && base.Flag.N != 0 {
   531  			// For a range body closure, keep its closure pointer live on the
   532  			// stack with a special name, so the debugger can look for it and
   533  			// find the parent frame.
   534  			sym := &types.Sym{Name: ".closureptr", Pkg: types.LocalPkg}
   535  			cloSlot := s.curfn.NewLocal(src.NoXPos, sym, s.f.Config.Types.BytePtr)
   536  			cloSlot.SetUsed(true)
   537  			cloSlot.SetEsc(ir.EscNever)
   538  			cloSlot.SetAddrtaken(true)
   539  			s.f.CloSlot = cloSlot
   540  			s.vars[memVar] = s.newValue1Apos(ssaop.OpVarDef, types.TypeMem, cloSlot, s.mem(), false)
   541  			addr := s.addr(cloSlot)
   542  			s.store(s.f.Config.Types.BytePtr, addr, clo)
   543  			// Keep it from being dead-store eliminated.
   544  			s.vars[memVar] = s.newValue1Apos(ssaop.OpVarLive, types.TypeMem, cloSlot, s.mem(), false)
   545  		}
   546  		csiter := typecheck.NewClosureStructIter(fn.ClosureVars)
   547  		for {
   548  			n, typ, offset := csiter.Next()
   549  			if n == nil {
   550  				break
   551  			}
   552  
   553  			ptr := s.newValue1I(ssaop.OpOffPtr, types.NewPtr(typ), offset, clo)
   554  
   555  			// If n is a small variable captured by value, promote
   556  			// it to PAUTO so it can be converted to SSA.
   557  			//
   558  			// Note: While we never capture a variable by value if
   559  			// the user took its address, we may have generated
   560  			// runtime calls that did (#43701). Since we don't
   561  			// convert Addrtaken variables to SSA anyway, no point
   562  			// in promoting them either.
   563  			if n.Byval() && !n.Addrtaken() && ssa.CanSSA(n.Type()) {
   564  				n.Class = ir.PAUTO
   565  				fn.Dcl = append(fn.Dcl, n)
   566  				s.assign(n, s.load(n.Type(), ptr), false, 0)
   567  				continue
   568  			}
   569  
   570  			if !n.Byval() {
   571  				ptr = s.load(typ, ptr)
   572  			}
   573  			s.setHeapaddr(fn.Pos(), n, ptr)
   574  		}
   575  	}
   576  
   577  	// Convert the AST-based IR to the SSA-based IR
   578  	if s.instrumentEnterExit {
   579  		s.rtcall(ir.Syms.Racefuncenter, true, nil, s.newValue0(ssaop.OpGetCallerPC, types.Types[types.TUINTPTR]))
   580  	}
   581  	s.zeroResults()
   582  	s.paramsToHeap()
   583  	s.stmtList(fn.Body)
   584  
   585  	// fallthrough to exit
   586  	if s.curBlock != nil {
   587  		s.pushLine(fn.Endlineno)
   588  		s.exit()
   589  		s.popLine()
   590  	}
   591  
   592  	for _, b := range s.f.Blocks {
   593  		if b.Pos != src.NoXPos {
   594  			s.updateUnsetPredPos(b)
   595  		}
   596  	}
   597  
   598  	if htmlWriter.Enabled() {
   599  		htmlWriter.WritePhase("before insert phis", "before insert phis")
   600  	}
   601  
   602  	s.insertPhis()
   603  
   604  	// Main call to ssa package to compile function
   605  	compiler.Compile(s.f, htmlWriter)
   606  
   607  	fe.AllocFrame(s.f)
   608  
   609  	if len(s.openDefers) != 0 {
   610  		s.emitOpenDeferInfo()
   611  	}
   612  
   613  	// Record incoming parameter spill information for morestack calls emitted in the assembler.
   614  	// This is done here, using all the parameters (used, partially used, and unused) because
   615  	// it mimics the behavior of the former ABI (everything stored) and because it's not 100%
   616  	// clear if naming conventions are respected in autogenerated code.
   617  	// TODO figure out exactly what's unused, don't spill it. Make liveness fine-grained, also.
   618  	for _, p := range params.InParams() {
   619  		typs, offs := p.RegisterTypesAndOffsets()
   620  		if len(offs) < len(typs) {
   621  			s.Fatalf("len(offs)=%d < len(typs)=%d, params=\n%s", len(offs), len(typs), params)
   622  		}
   623  		for i, t := range typs {
   624  			o := offs[i]                // offset within parameter
   625  			fo := p.FrameOffset(params) // offset of parameter in frame
   626  			reg := ssa.ObjRegForAbiReg(p.Registers[i], s.f.Config)
   627  			s.f.RegArgs = append(s.f.RegArgs, ssa.Spill{Reg: reg, Offset: fo + o, Type: t})
   628  		}
   629  	}
   630  
   631  	return s.f, htmlWriter
   632  }
   633  
   634  func (s *state) storeParameterRegsToStack(abi *abi.ABIConfig, paramAssignment *abi.ABIParamAssignment, n *ir.Name, addr *ssa.Value, pointersOnly bool) {
   635  	typs, offs := paramAssignment.RegisterTypesAndOffsets()
   636  	for i, t := range typs {
   637  		if pointersOnly && !t.IsPtrShaped() {
   638  			continue
   639  		}
   640  		r := paramAssignment.Registers[i]
   641  		o := offs[i]
   642  		op, reg := ssa.ArgOpAndRegisterFor(r, abi)
   643  		aux := &ssa.AuxNameOffset{Name: n, Offset: o}
   644  		v := s.newValue0I(op, t, reg)
   645  		v.Aux = aux
   646  		p := s.newValue1I(ssaop.OpOffPtr, types.NewPtr(t), o, addr)
   647  		s.store(t, p, v)
   648  	}
   649  }
   650  
   651  // zeroResults zeros the return values at the start of the function.
   652  // We need to do this very early in the function.  Defer might stop a
   653  // panic and show the return values as they exist at the time of
   654  // panic.  For precise stacks, the garbage collector assumes results
   655  // are always live, so we need to zero them before any allocations,
   656  // even allocations to move params/results to the heap.
   657  func (s *state) zeroResults() {
   658  	for _, f := range s.curfn.Type().Results() {
   659  		n := f.Nname.(*ir.Name)
   660  		if !n.OnStack() {
   661  			// The local which points to the return value is the
   662  			// thing that needs zeroing. This is already handled
   663  			// by a Needzero annotation in plive.go:(*liveness).epilogue.
   664  			continue
   665  		}
   666  		// Zero the stack location containing f.
   667  		if typ := n.Type(); ssa.CanSSA(typ) {
   668  			s.assign(n, s.zeroVal(typ), false, 0)
   669  		} else {
   670  			if typ.HasPointers() || ssa.IsMergeCandidate(n) {
   671  				s.vars[memVar] = s.newValue1A(ssaop.OpVarDef, types.TypeMem, n, s.mem())
   672  			}
   673  			s.zero(n.Type(), s.decladdrs[n])
   674  		}
   675  	}
   676  }
   677  
   678  // paramsToHeap produces code to allocate memory for heap-escaped parameters
   679  // and to copy non-result parameters' values from the stack.
   680  func (s *state) paramsToHeap() {
   681  	do := func(params []*types.Field) {
   682  		for _, f := range params {
   683  			if f.Nname == nil {
   684  				continue // anonymous or blank parameter
   685  			}
   686  			n := f.Nname.(*ir.Name)
   687  			if ir.IsBlank(n) || n.OnStack() {
   688  				continue
   689  			}
   690  			s.newHeapaddr(n)
   691  			if n.Class == ir.PPARAM {
   692  				s.move(n.Type(), s.expr(n.Heapaddr), s.decladdrs[n])
   693  			}
   694  		}
   695  	}
   696  
   697  	typ := s.curfn.Type()
   698  	do(typ.Recvs())
   699  	do(typ.Params())
   700  	do(typ.Results())
   701  }
   702  
   703  // allocSizeAndAlign returns the size and alignment of t.
   704  // Normally just t.Size() and t.Alignment(), but there
   705  // is a special case to handle 64-bit atomics on 32-bit systems.
   706  func allocSizeAndAlign(t *types.Type) (int64, int64) {
   707  	size, align := t.Size(), t.Alignment()
   708  	if types.PtrSize == 4 && align == 4 && size >= 8 {
   709  		// For 64-bit atomics on 32-bit systems.
   710  		size = types.RoundUp(size, 8)
   711  		align = 8
   712  	}
   713  	return size, align
   714  }
   715  func allocSize(t *types.Type) int64 {
   716  	size, _ := allocSizeAndAlign(t)
   717  	return size
   718  }
   719  func allocAlign(t *types.Type) int64 {
   720  	_, align := allocSizeAndAlign(t)
   721  	return align
   722  }
   723  
   724  // newHeapaddr allocates heap memory for n and sets its heap address.
   725  func (s *state) newHeapaddr(n *ir.Name) {
   726  	size := allocSize(n.Type())
   727  	if n.Type().HasPointers() || size >= maxAggregatedHeapAllocation || size == 0 {
   728  		s.setHeapaddr(n.Pos(), n, s.newObject(n.Type()))
   729  		return
   730  	}
   731  
   732  	// Do we have room together with our pending allocations?
   733  	// If not, flush all the current ones.
   734  	var used int64
   735  	for _, v := range s.pendingHeapAllocations {
   736  		used += allocSize(v.Type.Elem())
   737  	}
   738  	if used+size > maxAggregatedHeapAllocation {
   739  		s.flushPendingHeapAllocations()
   740  	}
   741  
   742  	var allocCall *ssa.Value // (SelectN [0] (call of runtime.newobject))
   743  	if len(s.pendingHeapAllocations) == 0 {
   744  		// Make an allocation, but the type being allocated is just
   745  		// the first pending object. We will come back and update it
   746  		// later if needed.
   747  		allocCall = s.newObjectNonSpecialized(n.Type(), nil)
   748  	} else {
   749  		allocCall = s.pendingHeapAllocations[0].Args[0]
   750  	}
   751  	// v is an offset to the shared allocation. Offsets are dummy 0s for now.
   752  	v := s.newValue1I(ssaop.OpOffPtr, n.Type().PtrTo(), 0, allocCall)
   753  
   754  	// Add to list of pending allocations.
   755  	s.pendingHeapAllocations = append(s.pendingHeapAllocations, v)
   756  
   757  	// Finally, record for posterity.
   758  	s.setHeapaddr(n.Pos(), n, v)
   759  }
   760  
   761  func (s *state) flushPendingHeapAllocations() {
   762  	pending := s.pendingHeapAllocations
   763  	if len(pending) == 0 {
   764  		return // nothing to do
   765  	}
   766  	s.pendingHeapAllocations = nil // reset state
   767  	ptr := pending[0].Args[0]      // The SelectN [0] op
   768  	call := ptr.Args[0]            // The runtime.newobject call
   769  
   770  	if len(pending) == 1 {
   771  		// Just a single object, do a standard allocation.
   772  		v := pending[0]
   773  		v.Op = ssaop.OpCopy // instead of OffPtr [0]
   774  		return
   775  	}
   776  
   777  	// Sort in decreasing alignment.
   778  	// This way we never have to worry about padding.
   779  	// (Stable not required; just cleaner to keep program order among equal alignments.)
   780  	slices.SortStableFunc(pending, func(x, y *ssa.Value) int {
   781  		return cmp.Compare(allocAlign(y.Type.Elem()), allocAlign(x.Type.Elem()))
   782  	})
   783  
   784  	// Figure out how much data we need allocate.
   785  	var size int64
   786  	for _, v := range pending {
   787  		v.AuxInt = size // Adjust OffPtr to the right value while we are here.
   788  		size += allocSize(v.Type.Elem())
   789  	}
   790  	align := allocAlign(pending[0].Type.Elem())
   791  	size = types.RoundUp(size, align)
   792  
   793  	// Convert newObject call to a mallocgc call.
   794  	args := []*ssa.Value{
   795  		s.constInt(types.Types[types.TUINTPTR], size),
   796  		s.constNil(call.Args[0].Type), // a nil *runtime._type
   797  		s.constBool(true),             // needZero TODO: false is ok?
   798  		call.Args[1],                  // memory
   799  	}
   800  	mallocSym := ir.Syms.MallocGC
   801  	if specialMallocSym := s.specializedMallocSym(size, false); specialMallocSym != nil {
   802  		mallocSym = specialMallocSym
   803  	}
   804  	call.Aux = ssa.StaticAuxCall(mallocSym, s.f.ABIDefault.ABIAnalyzeTypes(
   805  		[]*types.Type{args[0].Type, args[1].Type, args[2].Type},
   806  		[]*types.Type{types.Types[types.TUNSAFEPTR]},
   807  	))
   808  	call.AuxInt = 4 * s.config.PtrSize // arg+results size, uintptr/ptr/bool/ptr
   809  	call.SetArgs4(args[0], args[1], args[2], args[3])
   810  	// TODO: figure out how to pass alignment to runtime
   811  
   812  	call.Type = types.NewTuple(types.Types[types.TUNSAFEPTR], types.TypeMem)
   813  	ptr.Type = types.Types[types.TUNSAFEPTR]
   814  }
   815  
   816  func (s *state) specializedMallocSym(size int64, hasPointers bool) *obj.LSym {
   817  	if !s.sizeSpecializedMallocEnabled() {
   818  		return nil
   819  	}
   820  	const specializedMallocMax = 80 // This must match the constant in mkmalloc.
   821  	if size > specializedMallocMax {
   822  		return nil
   823  	}
   824  	divRoundUp := func(n, a uintptr) uintptr { return (n + a - 1) / a }
   825  	sizeClass := gc.SizeToSizeClass8[divRoundUp(uintptr(size), gc.SmallSizeDiv)]
   826  	if hasPointers {
   827  		return ir.Syms.MallocGCSmallScanNoHeader[sizeClass]
   828  	}
   829  	if size < gc.TinySize {
   830  		return ir.Syms.MallocGCTiny
   831  	}
   832  	return ir.Syms.MallocGCSmallNoScan[sizeClass]
   833  }
   834  
   835  func (s *state) sizeSpecializedMallocEnabled() bool {
   836  	if base.Flag.CompilingRuntime {
   837  		// The compiler forces the values of the asan, msan, and race flags to false if
   838  		// we're compiling the runtime, so we lose the information about whether we're
   839  		// building in asan, msan, or race mode. Because the specialized functions don't
   840  		// work in that mode, just turn if off in that case.
   841  		// TODO(matloob): Save the information about whether the flags were passed in
   842  		// originally so we can turn off size specialized malloc in that case instead
   843  		// using Instrumenting below. Then we can remove this condition.
   844  		return false
   845  	}
   846  
   847  	return !base.Flag.Cfg.Instrumenting
   848  }
   849  
   850  // setHeapaddr allocates a new PAUTO variable to store ptr (which must be non-nil)
   851  // and then sets it as n's heap address.
   852  func (s *state) setHeapaddr(pos src.XPos, n *ir.Name, ptr *ssa.Value) {
   853  	if !ptr.Type.IsPtr() || !types.Identical(n.Type(), ptr.Type.Elem()) {
   854  		base.FatalfAt(n.Pos(), "setHeapaddr %L with type %v", n, ptr.Type)
   855  	}
   856  
   857  	// Declare variable to hold address.
   858  	sym := &types.Sym{Name: "&" + n.Sym().Name, Pkg: types.LocalPkg}
   859  	addr := s.curfn.NewLocal(pos, sym, types.NewPtr(n.Type()))
   860  	addr.SetUsed(true)
   861  	types.CalcSize(addr.Type())
   862  
   863  	if n.Class == ir.PPARAMOUT {
   864  		addr.SetIsOutputParamHeapAddr(true)
   865  	}
   866  
   867  	n.Heapaddr = addr
   868  	s.assign(addr, ptr, false, 0)
   869  }
   870  
   871  // newObject returns an SSA value denoting new(typ).
   872  func (s *state) newObject(typ *types.Type) *ssa.Value {
   873  	if typ.Size() == 0 {
   874  		return s.newValue1A(ssaop.OpAddr, types.NewPtr(typ), ir.Syms.Zerobase, s.sb)
   875  	}
   876  	rtype := s.reflectType(typ)
   877  	if specialMallocSym := s.specializedMallocSym(typ.Size(), typ.HasPointers()); specialMallocSym != nil {
   878  		return s.rtcall(specialMallocSym, true, []*types.Type{types.NewPtr(typ)},
   879  			s.constInt(types.Types[types.TUINTPTR], typ.Size()),
   880  			rtype,
   881  			s.constBool(true),
   882  		)[0]
   883  	}
   884  	return s.rtcall(ir.Syms.Newobject, true, []*types.Type{types.NewPtr(typ)}, rtype)[0]
   885  }
   886  
   887  // newObjectNonSpecialized returns an SSA value denoting new(typ). It does
   888  // not produce size-specialized malloc functions.
   889  func (s *state) newObjectNonSpecialized(typ *types.Type, rtype *ssa.Value) *ssa.Value {
   890  	if typ.Size() == 0 {
   891  		return s.newValue1A(ssaop.OpAddr, types.NewPtr(typ), ir.Syms.Zerobase, s.sb)
   892  	}
   893  	if rtype == nil {
   894  		rtype = s.reflectType(typ)
   895  	}
   896  	return s.rtcall(ir.Syms.Newobject, true, []*types.Type{types.NewPtr(typ)}, rtype)[0]
   897  }
   898  
   899  func (s *state) checkPtrAlignment(n *ir.ConvExpr, v *ssa.Value, count *ssa.Value) {
   900  	if !n.Type().IsPtr() {
   901  		s.Fatalf("expected pointer type: %v", n.Type())
   902  	}
   903  	elem, rtypeExpr := n.Type().Elem(), n.ElemRType
   904  	if count != nil {
   905  		if !elem.IsArray() {
   906  			s.Fatalf("expected array type: %v", elem)
   907  		}
   908  		elem, rtypeExpr = elem.Elem(), n.ElemElemRType
   909  	}
   910  	size := elem.Size()
   911  	// Casting from larger type to smaller one is ok, so for smallest type, do nothing.
   912  	if elem.Alignment() == 1 && (size == 0 || size == 1 || count == nil) {
   913  		return
   914  	}
   915  	if count == nil {
   916  		count = s.constInt(types.Types[types.TUINTPTR], 1)
   917  	}
   918  	if count.Type.Size() != s.config.PtrSize {
   919  		s.Fatalf("expected count fit to a uintptr size, have: %d, want: %d", count.Type.Size(), s.config.PtrSize)
   920  	}
   921  	var rtype *ssa.Value
   922  	if rtypeExpr != nil {
   923  		rtype = s.expr(rtypeExpr)
   924  	} else {
   925  		rtype = s.reflectType(elem)
   926  	}
   927  	s.rtcall(ir.Syms.CheckPtrAlignment, true, nil, v, rtype, count)
   928  }
   929  
   930  // reflectType returns an SSA value representing a pointer to typ's
   931  // reflection type descriptor.
   932  func (s *state) reflectType(typ *types.Type) *ssa.Value {
   933  	// TODO(mdempsky): Make this Fatalf under Unified IR; frontend needs
   934  	// to supply RType expressions.
   935  	lsym := reflectdata.TypeLinksym(typ)
   936  	return s.entryNewValue1A(ssaop.OpAddr, types.NewPtr(types.Types[types.TUINT8]), lsym, s.sb)
   937  }
   938  
   939  func dumpSourcesColumn(writer *ssahtml.HTMLWriter, fn *ir.Func) {
   940  	// Read sources of target function fn.
   941  	fname := base.Ctxt.PosTable.Pos(fn.Pos()).Filename()
   942  	targetFn, err := readFuncLines(fname, fn.Pos().Line(), fn.Endlineno.Line())
   943  	if err != nil {
   944  		writer.Logf("cannot read sources for function %v: %v", fn, err)
   945  	}
   946  
   947  	// Read sources of inlined functions.
   948  	var inlFns []*ssahtml.FuncLines
   949  	for _, fi := range ssaDumpInlined {
   950  		elno := fi.Endlineno
   951  		fname := base.Ctxt.PosTable.Pos(fi.Pos()).Filename()
   952  		fnLines, err := readFuncLines(fname, fi.Pos().Line(), elno.Line())
   953  		if err != nil {
   954  			writer.Logf("cannot read sources for inlined function %v: %v", fi, err)
   955  			continue
   956  		}
   957  		inlFns = append(inlFns, fnLines)
   958  	}
   959  
   960  	slices.SortFunc(inlFns, ssahtml.ByTopoCmp)
   961  	if targetFn != nil {
   962  		inlFns = append([]*ssahtml.FuncLines{targetFn}, inlFns...)
   963  	}
   964  
   965  	writer.WriteSources("sources", inlFns)
   966  }
   967  
   968  func readFuncLines(file string, start, end uint) (*ssahtml.FuncLines, error) {
   969  	f, err := os.Open(os.ExpandEnv(file))
   970  	if err != nil {
   971  		return nil, err
   972  	}
   973  	defer f.Close() // ignore error
   974  	var lines []string
   975  	ln := uint(1)
   976  	scanner := bufio.NewScanner(f)
   977  	for scanner.Scan() && ln <= end {
   978  		if ln >= start {
   979  			lines = append(lines, scanner.Text())
   980  		}
   981  		ln++
   982  	}
   983  	if err := scanner.Err(); err != nil {
   984  		return nil, fmt.Errorf("scanning %s: %v", file, err)
   985  	}
   986  	return &ssahtml.FuncLines{Filename: file, StartLineno: start, Lines: lines}, nil
   987  }
   988  
   989  // updateUnsetPredPos propagates the earliest-value position information for b
   990  // towards all of b's predecessors that need a position, and recurs on that
   991  // predecessor if its position is updated. B should have a non-empty position.
   992  func (s *state) updateUnsetPredPos(b *ssa.Block) {
   993  	if b.Pos == src.NoXPos {
   994  		s.Fatalf("Block %s should have a position", b)
   995  	}
   996  	bestPos := src.NoXPos
   997  	for _, e := range b.Preds {
   998  		p := e.Block()
   999  		if !p.LackingPos() {
  1000  			continue
  1001  		}
  1002  		if bestPos == src.NoXPos {
  1003  			bestPos = b.Pos
  1004  			for _, v := range b.Values {
  1005  				if v.LackingPos() {
  1006  					continue
  1007  				}
  1008  				if v.Pos != src.NoXPos {
  1009  					// Assume values are still in roughly textual order;
  1010  					// TODO: could also seek minimum position?
  1011  					bestPos = v.Pos
  1012  					break
  1013  				}
  1014  			}
  1015  		}
  1016  		p.Pos = bestPos
  1017  		s.updateUnsetPredPos(p) // We do not expect long chains of these, thus recursion is okay.
  1018  	}
  1019  }
  1020  
  1021  // Information about each open-coded defer.
  1022  type openDeferInfo struct {
  1023  	// The node representing the call of the defer
  1024  	n *ir.CallExpr
  1025  	// If defer call is closure call, the address of the argtmp where the
  1026  	// closure is stored.
  1027  	closure *ssa.Value
  1028  	// The node representing the argtmp where the closure is stored - used for
  1029  	// function, method, or interface call, to store a closure that panic
  1030  	// processing can use for this defer.
  1031  	closureNode *ir.Name
  1032  }
  1033  
  1034  type state struct {
  1035  	// configuration (arch) information
  1036  	config *ssa.Config
  1037  
  1038  	// function we're building
  1039  	f *ssa.Func
  1040  
  1041  	// Node for function
  1042  	curfn *ir.Func
  1043  
  1044  	// labels in f
  1045  	labels map[string]*ssaLabel
  1046  
  1047  	// unlabeled break and continue statement tracking
  1048  	breakTo    *ssa.Block // current target for plain break statement
  1049  	continueTo *ssa.Block // current target for plain continue statement
  1050  
  1051  	// current location where we're interpreting the AST
  1052  	curBlock *ssa.Block
  1053  
  1054  	// variable assignments in the current block (map from variable symbol to ssa value)
  1055  	// *Node is the unique identifier (an ONAME Node) for the variable.
  1056  	// TODO: keep a single varnum map, then make all of these maps slices instead?
  1057  	vars map[ir.Node]*ssa.Value
  1058  
  1059  	// fwdVars are variables that are used before they are defined in the current block.
  1060  	// This map exists just to coalesce multiple references into a single FwdRef op.
  1061  	// *Node is the unique identifier (an ONAME Node) for the variable.
  1062  	fwdVars map[ir.Node]*ssa.Value
  1063  
  1064  	// all defined variables at the end of each block. Indexed by block ID.
  1065  	defvars []map[ir.Node]*ssa.Value
  1066  
  1067  	// addresses of PPARAM and PPARAMOUT variables on the stack.
  1068  	decladdrs map[*ir.Name]*ssa.Value
  1069  
  1070  	// starting values. Memory, stack pointer, and globals pointer
  1071  	startmem *ssa.Value
  1072  	sp       *ssa.Value
  1073  	sb       *ssa.Value
  1074  	// value representing address of where deferBits autotmp is stored
  1075  	deferBitsAddr *ssa.Value
  1076  	deferBitsTemp *ir.Name
  1077  
  1078  	// line number stack. The current line number is top of stack
  1079  	line []src.XPos
  1080  	// the last line number processed; it may have been popped
  1081  	lastPos src.XPos
  1082  
  1083  	// list of panic calls by function name and line number.
  1084  	// Used to deduplicate panic calls.
  1085  	panics map[funcLine]*ssa.Block
  1086  
  1087  	cgoUnsafeArgs       bool
  1088  	hasdefer            bool // whether the function contains a defer statement
  1089  	softFloat           bool
  1090  	hasOpenDefers       bool // whether we are doing open-coded defers
  1091  	checkPtrEnabled     bool // whether to insert checkptr instrumentation
  1092  	instrumentEnterExit bool // whether to instrument function enter/exit
  1093  	instrumentMemory    bool // whether to instrument memory operations
  1094  
  1095  	// If doing open-coded defers, list of info about the defer calls in
  1096  	// scanning order. Hence, at exit we should run these defers in reverse
  1097  	// order of this list
  1098  	openDefers []*openDeferInfo
  1099  	// For open-coded defers, this is the beginning and end blocks of the last
  1100  	// defer exit code that we have generated so far. We use these to share
  1101  	// code between exits if the shareDeferExits option (disabled by default)
  1102  	// is on.
  1103  	lastDeferExit       *ssa.Block // Entry block of last defer exit code we generated
  1104  	lastDeferFinalBlock *ssa.Block // Final block of last defer exit code we generated
  1105  	lastDeferCount      int        // Number of defers encountered at that point
  1106  
  1107  	prevCall *ssa.Value // the previous call; use this to tie results to the call op.
  1108  
  1109  	// List of allocations in the current block that are still pending.
  1110  	// They are all (OffPtr (Select0 (runtime call))) and have the correct types,
  1111  	// but the offsets are not set yet, and the type of the runtime call is also not final.
  1112  	pendingHeapAllocations []*ssa.Value
  1113  
  1114  	// First argument of append calls that could be stack allocated.
  1115  	appendTargets map[ir.Node]bool
  1116  
  1117  	// Block starting position, indexed by block id.
  1118  	blockStarts []src.XPos
  1119  
  1120  	// Information for stack allocation. Indexed by the first argument
  1121  	// to an append call. Normally a slice-typed variable, but not always.
  1122  	backingStores map[ir.Node]*backingStoreInfo
  1123  }
  1124  
  1125  type backingStoreInfo struct {
  1126  	// Size of backing store array (in elements)
  1127  	K int64
  1128  	// Stack-allocated backing store variable.
  1129  	store *ir.Name
  1130  	// Dynamic boolean variable marking the fact that we used this backing store.
  1131  	used *ir.Name
  1132  	// Have we used this variable statically yet? This is just a hint
  1133  	// to avoid checking the dynamic variable if the answer is obvious.
  1134  	// (usedStatic == true implies used == true)
  1135  	usedStatic bool
  1136  }
  1137  
  1138  type funcLine struct {
  1139  	f    *obj.LSym
  1140  	base *src.PosBase
  1141  	line uint
  1142  }
  1143  
  1144  type ssaLabel struct {
  1145  	target         *ssa.Block // block identified by this label
  1146  	breakTarget    *ssa.Block // block to break to in control flow node identified by this label
  1147  	continueTarget *ssa.Block // block to continue to in control flow node identified by this label
  1148  }
  1149  
  1150  // label returns the label associated with sym, creating it if necessary.
  1151  func (s *state) label(sym *types.Sym) *ssaLabel {
  1152  	lab := s.labels[sym.Name]
  1153  	if lab == nil {
  1154  		lab = new(ssaLabel)
  1155  		s.labels[sym.Name] = lab
  1156  	}
  1157  	return lab
  1158  }
  1159  
  1160  func (s *state) Logf(msg string, args ...any) { s.f.Logf(msg, args...) }
  1161  func (s *state) Log() bool                    { return s.f.Log() }
  1162  func (s *state) Fatalf(msg string, args ...any) {
  1163  	s.f.Frontend().Fatalf(s.peekPos(), msg, args...)
  1164  }
  1165  func (s *state) Warnl(pos src.XPos, msg string, args ...any) { s.f.Warnl(pos, msg, args...) }
  1166  func (s *state) Debug_checknil() bool                        { return s.f.Frontend().Debug_checknil() }
  1167  
  1168  func ssaMarker(name string) *ir.Name {
  1169  	return ir.NewNameAt(base.Pos, &types.Sym{Name: name}, nil)
  1170  }
  1171  
  1172  var (
  1173  	// marker node for the memory variable
  1174  	memVar = ssaMarker("mem")
  1175  
  1176  	// marker nodes for temporary variables
  1177  	ptrVar       = ssaMarker("ptr")
  1178  	lenVar       = ssaMarker("len")
  1179  	capVar       = ssaMarker("cap")
  1180  	typVar       = ssaMarker("typ")
  1181  	okVar        = ssaMarker("ok")
  1182  	deferBitsVar = ssaMarker("deferBits")
  1183  	hashVar      = ssaMarker("hash")
  1184  )
  1185  
  1186  // startBlock sets the current block we're generating code in to b.
  1187  func (s *state) startBlock(b *ssa.Block) {
  1188  	if s.curBlock != nil {
  1189  		s.Fatalf("starting block %v when block %v has not ended", b, s.curBlock)
  1190  	}
  1191  	s.curBlock = b
  1192  	s.vars = map[ir.Node]*ssa.Value{}
  1193  	clear(s.fwdVars)
  1194  	for len(s.blockStarts) <= int(b.ID) {
  1195  		s.blockStarts = append(s.blockStarts, src.NoXPos)
  1196  	}
  1197  }
  1198  
  1199  // endBlock marks the end of generating code for the current block.
  1200  // Returns the (former) current block. Returns nil if there is no current
  1201  // block, i.e. if no code flows to the current execution point.
  1202  func (s *state) endBlock() *ssa.Block {
  1203  	b := s.curBlock
  1204  	if b == nil {
  1205  		return nil
  1206  	}
  1207  
  1208  	s.flushPendingHeapAllocations()
  1209  
  1210  	for len(s.defvars) <= int(b.ID) {
  1211  		s.defvars = append(s.defvars, nil)
  1212  	}
  1213  	s.defvars[b.ID] = s.vars
  1214  	s.curBlock = nil
  1215  	s.vars = nil
  1216  	if b.LackingPos() {
  1217  		// Empty plain blocks get the line of their successor (handled after all blocks created),
  1218  		// except for increment blocks in For statements (handled in ssa conversion of OFOR),
  1219  		// and for blocks ending in GOTO/BREAK/CONTINUE.
  1220  		b.Pos = src.NoXPos
  1221  	} else {
  1222  		b.Pos = s.lastPos
  1223  		if s.blockStarts[b.ID] == src.NoXPos {
  1224  			s.blockStarts[b.ID] = s.lastPos
  1225  		}
  1226  	}
  1227  	return b
  1228  }
  1229  
  1230  // pushLine pushes a line number on the line number stack.
  1231  func (s *state) pushLine(line src.XPos) {
  1232  	if !line.IsKnown() {
  1233  		// the frontend may emit node with line number missing,
  1234  		// use the parent line number in this case.
  1235  		line = s.peekPos()
  1236  		if base.Flag.K != 0 {
  1237  			base.Warn("buildssa: unknown position (line 0)")
  1238  		}
  1239  	} else {
  1240  		s.lastPos = line
  1241  	}
  1242  	// The first position we see for a new block is its starting position
  1243  	// (the line number for its phis, if any).
  1244  	if b := s.curBlock; b != nil && s.blockStarts[b.ID] == src.NoXPos {
  1245  		s.blockStarts[b.ID] = line
  1246  	}
  1247  
  1248  	s.line = append(s.line, line)
  1249  }
  1250  
  1251  // popLine pops the top of the line number stack.
  1252  func (s *state) popLine() {
  1253  	s.line = s.line[:len(s.line)-1]
  1254  }
  1255  
  1256  // peekPos peeks the top of the line number stack.
  1257  func (s *state) peekPos() src.XPos {
  1258  	return s.line[len(s.line)-1]
  1259  }
  1260  
  1261  // newValue0 adds a new value with no arguments to the current block.
  1262  func (s *state) newValue0(op ssaop.Op, t *types.Type) *ssa.Value {
  1263  	return s.curBlock.NewValue0(s.peekPos(), op, t)
  1264  }
  1265  
  1266  // newValue0A adds a new value with no arguments and an aux value to the current block.
  1267  func (s *state) newValue0A(op ssaop.Op, t *types.Type, aux ssa.Aux) *ssa.Value {
  1268  	return s.curBlock.NewValue0A(s.peekPos(), op, t, aux)
  1269  }
  1270  
  1271  // newValue0I adds a new value with no arguments and an auxint value to the current block.
  1272  func (s *state) newValue0I(op ssaop.Op, t *types.Type, auxint int64) *ssa.Value {
  1273  	return s.curBlock.NewValue0I(s.peekPos(), op, t, auxint)
  1274  }
  1275  
  1276  // newValue1 adds a new value with one argument to the current block.
  1277  func (s *state) newValue1(op ssaop.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1278  	return s.curBlock.NewValue1(s.peekPos(), op, t, arg)
  1279  }
  1280  
  1281  // newValue1A adds a new value with one argument and an aux value to the current block.
  1282  func (s *state) newValue1A(op ssaop.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value) *ssa.Value {
  1283  	return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
  1284  }
  1285  
  1286  // newValue1Apos adds a new value with one argument and an aux value to the current block.
  1287  // isStmt determines whether the created values may be a statement or not
  1288  // (i.e., false means never, yes means maybe).
  1289  func (s *state) newValue1Apos(op ssaop.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value, isStmt bool) *ssa.Value {
  1290  	if isStmt {
  1291  		return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
  1292  	}
  1293  	return s.curBlock.NewValue1A(s.peekPos().WithNotStmt(), op, t, aux, arg)
  1294  }
  1295  
  1296  // newValue1I adds a new value with one argument and an auxint value to the current block.
  1297  func (s *state) newValue1I(op ssaop.Op, t *types.Type, aux int64, arg *ssa.Value) *ssa.Value {
  1298  	return s.curBlock.NewValue1I(s.peekPos(), op, t, aux, arg)
  1299  }
  1300  
  1301  // newValue2 adds a new value with two arguments to the current block.
  1302  func (s *state) newValue2(op ssaop.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1303  	return s.curBlock.NewValue2(s.peekPos(), op, t, arg0, arg1)
  1304  }
  1305  
  1306  // newValue2A adds a new value with two arguments and an aux value to the current block.
  1307  func (s *state) newValue2A(op ssaop.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value) *ssa.Value {
  1308  	return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
  1309  }
  1310  
  1311  // newValue2Apos adds a new value with two arguments and an aux value to the current block.
  1312  // isStmt determines whether the created values may be a statement or not
  1313  // (i.e., false means never, yes means maybe).
  1314  func (s *state) newValue2Apos(op ssaop.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value, isStmt bool) *ssa.Value {
  1315  	if isStmt {
  1316  		return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
  1317  	}
  1318  	return s.curBlock.NewValue2A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1)
  1319  }
  1320  
  1321  // newValue2I adds a new value with two arguments and an auxint value to the current block.
  1322  func (s *state) newValue2I(op ssaop.Op, t *types.Type, aux int64, arg0, arg1 *ssa.Value) *ssa.Value {
  1323  	return s.curBlock.NewValue2I(s.peekPos(), op, t, aux, arg0, arg1)
  1324  }
  1325  
  1326  // newValue3 adds a new value with three arguments to the current block.
  1327  func (s *state) newValue3(op ssaop.Op, t *types.Type, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1328  	return s.curBlock.NewValue3(s.peekPos(), op, t, arg0, arg1, arg2)
  1329  }
  1330  
  1331  // newValue3I adds a new value with three arguments and an auxint value to the current block.
  1332  func (s *state) newValue3I(op ssaop.Op, t *types.Type, aux int64, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1333  	return s.curBlock.NewValue3I(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1334  }
  1335  
  1336  // newValue3A adds a new value with three arguments and an aux value to the current block.
  1337  func (s *state) newValue3A(op ssaop.Op, t *types.Type, aux ssa.Aux, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1338  	return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1339  }
  1340  
  1341  // newValue3Apos adds a new value with three arguments and an aux value to the current block.
  1342  // isStmt determines whether the created values may be a statement or not
  1343  // (i.e., false means never, yes means maybe).
  1344  func (s *state) newValue3Apos(op ssaop.Op, t *types.Type, aux ssa.Aux, arg0, arg1, arg2 *ssa.Value, isStmt bool) *ssa.Value {
  1345  	if isStmt {
  1346  		return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1347  	}
  1348  	return s.curBlock.NewValue3A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1, arg2)
  1349  }
  1350  
  1351  // newValue4 adds a new value with four arguments to the current block.
  1352  func (s *state) newValue4(op ssaop.Op, t *types.Type, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
  1353  	return s.curBlock.NewValue4(s.peekPos(), op, t, arg0, arg1, arg2, arg3)
  1354  }
  1355  
  1356  // newValue4A adds a new value with four arguments and an aux value to the current block.
  1357  func (s *state) newValue4A(op ssaop.Op, t *types.Type, aux ssa.Aux, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
  1358  	return s.curBlock.NewValue4A(s.peekPos(), op, t, aux, arg0, arg1, arg2, arg3)
  1359  }
  1360  
  1361  // newValue4I adds a new value with four arguments and an auxint value to the current block.
  1362  func (s *state) newValue4I(op ssaop.Op, t *types.Type, aux int64, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
  1363  	return s.curBlock.NewValue4I(s.peekPos(), op, t, aux, arg0, arg1, arg2, arg3)
  1364  }
  1365  
  1366  func (s *state) entryBlock() *ssa.Block {
  1367  	b := s.f.Entry
  1368  	if base.Flag.N > 0 && s.curBlock != nil {
  1369  		// If optimizations are off, allocate in current block instead. Since with -N
  1370  		// we're not doing the CSE or tighten passes, putting lots of stuff in the
  1371  		// entry block leads to O(n^2) entries in the live value map during regalloc.
  1372  		// See issue 45897.
  1373  		b = s.curBlock
  1374  	}
  1375  	return b
  1376  }
  1377  
  1378  // entryNewValue0 adds a new value with no arguments to the entry block.
  1379  func (s *state) entryNewValue0(op ssaop.Op, t *types.Type) *ssa.Value {
  1380  	return s.entryBlock().NewValue0(src.NoXPos, op, t)
  1381  }
  1382  
  1383  // entryNewValue0A adds a new value with no arguments and an aux value to the entry block.
  1384  func (s *state) entryNewValue0A(op ssaop.Op, t *types.Type, aux ssa.Aux) *ssa.Value {
  1385  	return s.entryBlock().NewValue0A(src.NoXPos, op, t, aux)
  1386  }
  1387  
  1388  // entryNewValue1 adds a new value with one argument to the entry block.
  1389  func (s *state) entryNewValue1(op ssaop.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1390  	return s.entryBlock().NewValue1(src.NoXPos, op, t, arg)
  1391  }
  1392  
  1393  // entryNewValue1I adds a new value with one argument and an auxint value to the entry block.
  1394  func (s *state) entryNewValue1I(op ssaop.Op, t *types.Type, auxint int64, arg *ssa.Value) *ssa.Value {
  1395  	return s.entryBlock().NewValue1I(src.NoXPos, op, t, auxint, arg)
  1396  }
  1397  
  1398  // entryNewValue1A adds a new value with one argument and an aux value to the entry block.
  1399  func (s *state) entryNewValue1A(op ssaop.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value) *ssa.Value {
  1400  	return s.entryBlock().NewValue1A(src.NoXPos, op, t, aux, arg)
  1401  }
  1402  
  1403  // entryNewValue2 adds a new value with two arguments to the entry block.
  1404  func (s *state) entryNewValue2(op ssaop.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1405  	return s.entryBlock().NewValue2(src.NoXPos, op, t, arg0, arg1)
  1406  }
  1407  
  1408  // entryNewValue2A adds a new value with two arguments and an aux value to the entry block.
  1409  func (s *state) entryNewValue2A(op ssaop.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value) *ssa.Value {
  1410  	return s.entryBlock().NewValue2A(src.NoXPos, op, t, aux, arg0, arg1)
  1411  }
  1412  
  1413  // const* routines add a new const value to the entry block.
  1414  func (s *state) constSlice(t *types.Type) *ssa.Value {
  1415  	return s.f.ConstSlice(t)
  1416  }
  1417  func (s *state) constInterface(t *types.Type) *ssa.Value {
  1418  	return s.f.ConstInterface(t)
  1419  }
  1420  func (s *state) constNil(t *types.Type) *ssa.Value { return s.f.ConstNil(t) }
  1421  func (s *state) constEmptyString(t *types.Type) *ssa.Value {
  1422  	return s.f.ConstEmptyString(t)
  1423  }
  1424  func (s *state) constBool(c bool) *ssa.Value {
  1425  	return s.f.ConstBool(types.Types[types.TBOOL], c)
  1426  }
  1427  func (s *state) constInt8(t *types.Type, c int8) *ssa.Value {
  1428  	return s.f.ConstInt8(t, c)
  1429  }
  1430  func (s *state) constInt16(t *types.Type, c int16) *ssa.Value {
  1431  	return s.f.ConstInt16(t, c)
  1432  }
  1433  func (s *state) constInt32(t *types.Type, c int32) *ssa.Value {
  1434  	return s.f.ConstInt32(t, c)
  1435  }
  1436  func (s *state) constInt64(t *types.Type, c int64) *ssa.Value {
  1437  	return s.f.ConstInt64(t, c)
  1438  }
  1439  func (s *state) constFloat32(t *types.Type, c float64) *ssa.Value {
  1440  	return s.f.ConstFloat32(t, c)
  1441  }
  1442  func (s *state) constFloat64(t *types.Type, c float64) *ssa.Value {
  1443  	return s.f.ConstFloat64(t, c)
  1444  }
  1445  func (s *state) constInt(t *types.Type, c int64) *ssa.Value {
  1446  	if s.config.PtrSize == 8 {
  1447  		return s.constInt64(t, c)
  1448  	}
  1449  	if int64(int32(c)) != c {
  1450  		s.Fatalf("integer constant too big %d", c)
  1451  	}
  1452  	return s.constInt32(t, int32(c))
  1453  }
  1454  
  1455  // newValueOrSfCall* are wrappers around newValue*, which may create a call to a
  1456  // soft-float runtime function instead (when emitting soft-float code).
  1457  func (s *state) newValueOrSfCall1(op ssaop.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1458  	if s.softFloat {
  1459  		if c, ok := s.sfcall(op, arg); ok {
  1460  			return c
  1461  		}
  1462  	}
  1463  	return s.newValue1(op, t, arg)
  1464  }
  1465  func (s *state) newValueOrSfCall2(op ssaop.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1466  	if s.softFloat {
  1467  		if c, ok := s.sfcall(op, arg0, arg1); ok {
  1468  			return c
  1469  		}
  1470  	}
  1471  	return s.newValue2(op, t, arg0, arg1)
  1472  }
  1473  
  1474  type instrumentKind uint8
  1475  
  1476  const (
  1477  	instrumentRead = iota
  1478  	instrumentWrite
  1479  	instrumentMove
  1480  )
  1481  
  1482  func (s *state) instrument(t *types.Type, addr *ssa.Value, kind instrumentKind) {
  1483  	s.instrument2(t, addr, nil, kind)
  1484  }
  1485  
  1486  // instrumentFields instruments a read/write operation on addr.
  1487  // If it is instrumenting for MSAN or ASAN and t is a struct type, it instruments
  1488  // operation for each field, instead of for the whole struct.
  1489  func (s *state) instrumentFields(t *types.Type, addr *ssa.Value, kind instrumentKind) {
  1490  	if !(base.Flag.MSan || base.Flag.ASan) || !isStructNotSIMD(t) {
  1491  		s.instrument(t, addr, kind)
  1492  		return
  1493  	}
  1494  	for _, f := range t.Fields() {
  1495  		if f.Sym.IsBlank() {
  1496  			continue
  1497  		}
  1498  		offptr := s.newValue1I(ssaop.OpOffPtr, types.NewPtr(f.Type), f.Offset, addr)
  1499  		s.instrumentFields(f.Type, offptr, kind)
  1500  	}
  1501  }
  1502  
  1503  func (s *state) instrumentMove(t *types.Type, dst, src *ssa.Value) {
  1504  	if base.Flag.MSan {
  1505  		s.instrument2(t, dst, src, instrumentMove)
  1506  	} else {
  1507  		s.instrument(t, src, instrumentRead)
  1508  		s.instrument(t, dst, instrumentWrite)
  1509  	}
  1510  }
  1511  
  1512  func (s *state) instrument2(t *types.Type, addr, addr2 *ssa.Value, kind instrumentKind) {
  1513  	if !s.instrumentMemory {
  1514  		return
  1515  	}
  1516  
  1517  	w := t.Size()
  1518  	if w == 0 {
  1519  		return // can't race on zero-sized things
  1520  	}
  1521  
  1522  	if ssa.IsSanitizerSafeAddr(addr) {
  1523  		return
  1524  	}
  1525  
  1526  	var fn *obj.LSym
  1527  	needWidth := false
  1528  
  1529  	if addr2 != nil && kind != instrumentMove {
  1530  		panic("instrument2: non-nil addr2 for non-move instrumentation")
  1531  	}
  1532  
  1533  	if base.Flag.MSan {
  1534  		switch kind {
  1535  		case instrumentRead:
  1536  			fn = ir.Syms.Msanread
  1537  		case instrumentWrite:
  1538  			fn = ir.Syms.Msanwrite
  1539  		case instrumentMove:
  1540  			fn = ir.Syms.Msanmove
  1541  		default:
  1542  			panic("unreachable")
  1543  		}
  1544  		needWidth = true
  1545  	} else if base.Flag.Race && t.NumComponents(types.CountBlankFields) > 1 {
  1546  		// for composite objects we have to write every address
  1547  		// because a write might happen to any subobject.
  1548  		// composites with only one element don't have subobjects, though.
  1549  		switch kind {
  1550  		case instrumentRead:
  1551  			fn = ir.Syms.Racereadrange
  1552  		case instrumentWrite:
  1553  			fn = ir.Syms.Racewriterange
  1554  		default:
  1555  			panic("unreachable")
  1556  		}
  1557  		needWidth = true
  1558  	} else if base.Flag.Race {
  1559  		// for non-composite objects we can write just the start
  1560  		// address, as any write must write the first byte.
  1561  		switch kind {
  1562  		case instrumentRead:
  1563  			fn = ir.Syms.Raceread
  1564  		case instrumentWrite:
  1565  			fn = ir.Syms.Racewrite
  1566  		default:
  1567  			panic("unreachable")
  1568  		}
  1569  	} else if base.Flag.ASan {
  1570  		switch kind {
  1571  		case instrumentRead:
  1572  			fn = ir.Syms.Asanread
  1573  		case instrumentWrite:
  1574  			fn = ir.Syms.Asanwrite
  1575  		default:
  1576  			panic("unreachable")
  1577  		}
  1578  		needWidth = true
  1579  	} else {
  1580  		panic("unreachable")
  1581  	}
  1582  
  1583  	args := []*ssa.Value{addr}
  1584  	if addr2 != nil {
  1585  		args = append(args, addr2)
  1586  	}
  1587  	if needWidth {
  1588  		args = append(args, s.constInt(types.Types[types.TUINTPTR], w))
  1589  	}
  1590  	s.rtcall(fn, true, nil, args...)
  1591  }
  1592  
  1593  func (s *state) load(t *types.Type, src *ssa.Value) *ssa.Value {
  1594  	s.instrumentFields(t, src, instrumentRead)
  1595  	return s.rawLoad(t, src)
  1596  }
  1597  
  1598  func (s *state) rawLoad(t *types.Type, src *ssa.Value) *ssa.Value {
  1599  	return s.newValue2(ssaop.OpLoad, t, src, s.mem())
  1600  }
  1601  
  1602  func (s *state) store(t *types.Type, dst, val *ssa.Value) {
  1603  	s.vars[memVar] = s.newValue3A(ssaop.OpStore, types.TypeMem, t, dst, val, s.mem())
  1604  }
  1605  
  1606  func (s *state) zero(t *types.Type, dst *ssa.Value) {
  1607  	s.instrument(t, dst, instrumentWrite)
  1608  	store := s.newValue2I(ssaop.OpZero, types.TypeMem, t.Size(), dst, s.mem())
  1609  	store.Aux = t
  1610  	s.vars[memVar] = store
  1611  }
  1612  
  1613  func (s *state) move(t *types.Type, dst, src *ssa.Value) {
  1614  	s.moveWhichMayOverlap(t, dst, src, false)
  1615  }
  1616  func (s *state) moveWhichMayOverlap(t *types.Type, dst, src *ssa.Value, mayOverlap bool) {
  1617  	s.instrumentMove(t, dst, src)
  1618  	if mayOverlap && t.IsArray() && t.NumElem() > 1 && !ssa.IsInlinableMemmove(dst, src, t.Size(), s.f.Config) {
  1619  		// Normally, when moving Go values of type T from one location to another,
  1620  		// we don't need to worry about partial overlaps. The two Ts must either be
  1621  		// in disjoint (nonoverlapping) memory or in exactly the same location.
  1622  		// There are 2 cases where this isn't true:
  1623  		//  1) Using unsafe you can arrange partial overlaps.
  1624  		//  2) Since Go 1.17, you can use a cast from a slice to a ptr-to-array.
  1625  		//     https://go.dev/ref/spec#Conversions_from_slice_to_array_pointer
  1626  		//     This feature can be used to construct partial overlaps of array types.
  1627  		//       var a [3]int
  1628  		//       p := (*[2]int)(a[:])
  1629  		//       q := (*[2]int)(a[1:])
  1630  		//       *p = *q
  1631  		// We don't care about solving 1. Or at least, we haven't historically
  1632  		// and no one has complained.
  1633  		// For 2, we need to ensure that if there might be partial overlap,
  1634  		// then we can't use OpMove; we must use memmove instead.
  1635  		// (memmove handles partial overlap by copying in the correct
  1636  		// direction. OpMove does not.)
  1637  		//
  1638  		// Note that we have to be careful here not to introduce a call when
  1639  		// we're marshaling arguments to a call or unmarshaling results from a call.
  1640  		// Cases where this is happening must pass mayOverlap to false.
  1641  		// (Currently this only happens when unmarshaling results of a call.)
  1642  		if t.HasPointers() {
  1643  			s.rtcall(ir.Syms.Typedmemmove, true, nil, s.reflectType(t), dst, src)
  1644  			// We would have otherwise implemented this move with straightline code,
  1645  			// including a write barrier. Pretend we issue a write barrier here,
  1646  			// so that the write barrier tests work. (Otherwise they'd need to know
  1647  			// the details of IsInlineableMemmove.)
  1648  			s.curfn.SetWBPos(s.peekPos())
  1649  		} else {
  1650  			s.rtcall(ir.Syms.Memmove, true, nil, dst, src, s.constInt(types.Types[types.TUINTPTR], t.Size()))
  1651  		}
  1652  		ssa.LogLargeCopy(s.f.Name, s.peekPos(), t.Size())
  1653  		return
  1654  	}
  1655  	store := s.newValue3I(ssaop.OpMove, types.TypeMem, t.Size(), dst, src, s.mem())
  1656  	store.Aux = t
  1657  	s.vars[memVar] = store
  1658  }
  1659  
  1660  // stmtList converts the statement list n to SSA and adds it to s.
  1661  func (s *state) stmtList(l ir.Nodes) {
  1662  	for _, n := range l {
  1663  		s.stmt(n)
  1664  	}
  1665  }
  1666  
  1667  func peelConvNop(n ir.Node) ir.Node {
  1668  	if n == nil {
  1669  		return n
  1670  	}
  1671  	for n.Op() == ir.OCONVNOP {
  1672  		n = n.(*ir.ConvExpr).X
  1673  	}
  1674  	return n
  1675  }
  1676  
  1677  // stmt converts the statement n to SSA and adds it to s.
  1678  func (s *state) stmt(n ir.Node) {
  1679  	s.pushLine(n.Pos())
  1680  	defer s.popLine()
  1681  
  1682  	// If s.curBlock is nil, and n isn't a label (which might have an associated goto somewhere),
  1683  	// then this code is dead. Stop here.
  1684  	if s.curBlock == nil && n.Op() != ir.OLABEL {
  1685  		return
  1686  	}
  1687  
  1688  	s.stmtList(n.Init())
  1689  	switch n.Op() {
  1690  
  1691  	case ir.OBLOCK:
  1692  		n := n.(*ir.BlockStmt)
  1693  		s.stmtList(n.List)
  1694  
  1695  	case ir.OFALL: // no-op
  1696  
  1697  	// Expression statements
  1698  	case ir.OCALLFUNC:
  1699  		n := n.(*ir.CallExpr)
  1700  		if ir.IsIntrinsicCall(n) {
  1701  			s.intrinsicCall(n)
  1702  			return
  1703  		}
  1704  		fallthrough
  1705  
  1706  	case ir.OCALLINTER:
  1707  		n := n.(*ir.CallExpr)
  1708  		s.callResult(n, callNormal)
  1709  		if n.Op() == ir.OCALLFUNC && n.Fun.Op() == ir.ONAME && n.Fun.(*ir.Name).Class == ir.PFUNC {
  1710  			if fn := n.Fun.Sym().Name; base.Flag.CompilingRuntime && fn == "throw" ||
  1711  				n.Fun.Sym().Pkg == ir.Pkgs.Runtime &&
  1712  					(fn == "throwinit" || fn == "gopanic" || fn == "panicwrap" || fn == "block" ||
  1713  						fn == "panicmakeslicelen" || fn == "panicmakeslicecap" || fn == "panicunsafeslicelen" ||
  1714  						fn == "panicunsafeslicenilptr" || fn == "panicunsafestringlen" || fn == "panicunsafestringnilptr" ||
  1715  						fn == "panicrangestate") {
  1716  				m := s.mem()
  1717  				b := s.endBlock()
  1718  				b.Kind = block.BlockExit
  1719  				b.SetControl(m)
  1720  				// TODO: never rewrite OPANIC to OCALLFUNC in the
  1721  				// first place. Need to wait until all backends
  1722  				// go through SSA.
  1723  			}
  1724  		}
  1725  	case ir.ODEFER:
  1726  		n := n.(*ir.GoDeferStmt)
  1727  		if base.Debug.Defer > 0 {
  1728  			var defertype string
  1729  			if s.hasOpenDefers {
  1730  				defertype = "open-coded"
  1731  			} else if n.Esc() == ir.EscNever {
  1732  				defertype = "stack-allocated"
  1733  			} else {
  1734  				defertype = "heap-allocated"
  1735  			}
  1736  			base.WarnfAt(n.Pos(), "%s defer", defertype)
  1737  		}
  1738  		if s.hasOpenDefers {
  1739  			s.openDeferRecord(n.Call.(*ir.CallExpr))
  1740  		} else {
  1741  			d := callDefer
  1742  			if n.Esc() == ir.EscNever && n.DeferAt == nil {
  1743  				d = callDeferStack
  1744  			}
  1745  			s.call(n.Call.(*ir.CallExpr), d, false, n.DeferAt)
  1746  		}
  1747  	case ir.OGO:
  1748  		n := n.(*ir.GoDeferStmt)
  1749  		s.callResult(n.Call.(*ir.CallExpr), callGo)
  1750  
  1751  	case ir.OAS2DOTTYPE:
  1752  		n := n.(*ir.AssignListStmt)
  1753  		var res, resok *ssa.Value
  1754  		if n.Rhs[0].Op() == ir.ODOTTYPE2 {
  1755  			res, resok = s.dottype(n.Rhs[0].(*ir.TypeAssertExpr), true)
  1756  		} else {
  1757  			res, resok = s.dynamicDottype(n.Rhs[0].(*ir.DynamicTypeAssertExpr), true)
  1758  		}
  1759  		deref := false
  1760  		if !ssa.CanSSA(n.Rhs[0].Type()) {
  1761  			if res.Op != ssaop.OpLoad {
  1762  				s.Fatalf("dottype of non-load")
  1763  			}
  1764  			mem := s.mem()
  1765  			if res.Args[1] != mem {
  1766  				s.Fatalf("memory no longer live from 2-result dottype load")
  1767  			}
  1768  			deref = true
  1769  			res = res.Args[0]
  1770  		}
  1771  		s.assign(n.Lhs[0], res, deref, 0)
  1772  		s.assign(n.Lhs[1], resok, false, 0)
  1773  		return
  1774  
  1775  	case ir.OAS2FUNC:
  1776  		// We come here only when it is an intrinsic call returning two values.
  1777  		n := n.(*ir.AssignListStmt)
  1778  		call := n.Rhs[0].(*ir.CallExpr)
  1779  		if !ir.IsIntrinsicCall(call) {
  1780  			s.Fatalf("non-intrinsic AS2FUNC not expanded %v", call)
  1781  		}
  1782  		v := s.intrinsicCall(call)
  1783  		v1 := s.newValue1(ssaop.OpSelect0, n.Lhs[0].Type(), v)
  1784  		v2 := s.newValue1(ssaop.OpSelect1, n.Lhs[1].Type(), v)
  1785  		s.assign(n.Lhs[0], v1, false, 0)
  1786  		s.assign(n.Lhs[1], v2, false, 0)
  1787  		return
  1788  
  1789  	case ir.ODCL:
  1790  		n := n.(*ir.Decl)
  1791  		if v := n.X; v.Esc() == ir.EscHeap {
  1792  			s.newHeapaddr(v)
  1793  		}
  1794  
  1795  	case ir.OLABEL:
  1796  		n := n.(*ir.LabelStmt)
  1797  		sym := n.Label
  1798  		if sym.IsBlank() {
  1799  			// Nothing to do because the label isn't targetable. See issue 52278.
  1800  			break
  1801  		}
  1802  		lab := s.label(sym)
  1803  
  1804  		// The label might already have a target block via a goto.
  1805  		if lab.target == nil {
  1806  			lab.target = s.f.NewBlock(block.BlockPlain)
  1807  		}
  1808  
  1809  		// Go to that label.
  1810  		// (We pretend "label:" is preceded by "goto label", unless the predecessor is unreachable.)
  1811  		if s.curBlock != nil {
  1812  			b := s.endBlock()
  1813  			b.AddEdgeTo(lab.target)
  1814  		}
  1815  		s.startBlock(lab.target)
  1816  
  1817  	case ir.OGOTO:
  1818  		n := n.(*ir.BranchStmt)
  1819  		sym := n.Label
  1820  
  1821  		lab := s.label(sym)
  1822  		if lab.target == nil {
  1823  			lab.target = s.f.NewBlock(block.BlockPlain)
  1824  		}
  1825  
  1826  		b := s.endBlock()
  1827  		b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
  1828  		b.AddEdgeTo(lab.target)
  1829  
  1830  	case ir.OAS:
  1831  		n := n.(*ir.AssignStmt)
  1832  		if n.X == n.Y && n.X.Op() == ir.ONAME {
  1833  			// An x=x assignment. No point in doing anything
  1834  			// here. In addition, skipping this assignment
  1835  			// prevents generating:
  1836  			//   VARDEF x
  1837  			//   COPY x -> x
  1838  			// which is bad because x is incorrectly considered
  1839  			// dead before the vardef. See issue #14904.
  1840  			return
  1841  		}
  1842  
  1843  		// mayOverlap keeps track of whether the LHS and RHS might
  1844  		// refer to partially overlapping memory. Partial overlapping can
  1845  		// only happen for arrays, see the comment in moveWhichMayOverlap.
  1846  		//
  1847  		// If both sides of the assignment are not dereferences, then partial
  1848  		// overlap can't happen. Partial overlap can only occur only when the
  1849  		// arrays referenced are strictly smaller parts of the same base array.
  1850  		// If one side of the assignment is a full array, then partial overlap
  1851  		// can't happen. (The arrays are either disjoint or identical.)
  1852  		ny := peelConvNop(n.Y)
  1853  		mayOverlap := n.X.Op() == ir.ODEREF && (n.Y != nil && ny.Op() == ir.ODEREF)
  1854  		if ny != nil && ny.Op() == ir.ODEREF {
  1855  			p := peelConvNop(ny.(*ir.StarExpr).X)
  1856  			if p.Op() == ir.OSPTR && p.(*ir.UnaryExpr).X.Type().IsString() {
  1857  				// Pointer fields of strings point to unmodifiable memory.
  1858  				// That memory can't overlap with the memory being written.
  1859  				mayOverlap = false
  1860  			}
  1861  		}
  1862  
  1863  		// Evaluate RHS.
  1864  		rhs := n.Y
  1865  		if rhs != nil {
  1866  			switch rhs.Op() {
  1867  			case ir.OSTRUCTLIT, ir.OARRAYLIT, ir.OSLICELIT:
  1868  				// All literals with nonzero fields have already been
  1869  				// rewritten during walk. Any that remain are just T{}
  1870  				// or equivalents. Use the zero value.
  1871  				if !ir.IsZero(rhs) {
  1872  					s.Fatalf("literal with nonzero value in SSA: %v", rhs)
  1873  				}
  1874  				rhs = nil
  1875  			case ir.OAPPEND:
  1876  				rhs := rhs.(*ir.CallExpr)
  1877  				// Check whether we're writing the result of an append back to the same slice.
  1878  				// If so, we handle it specially to avoid write barriers on the fast
  1879  				// (non-growth) path.
  1880  				if !ir.SameSafeExpr(n.X, rhs.Args[0]) || base.Flag.N != 0 {
  1881  					break
  1882  				}
  1883  				// If the slice can be SSA'd, it'll be on the stack,
  1884  				// so there will be no write barriers,
  1885  				// so there's no need to attempt to prevent them.
  1886  				if s.canSSA(n.X) {
  1887  					if base.Debug.Append > 0 { // replicating old diagnostic message
  1888  						base.WarnfAt(n.Pos(), "append: len-only update (in local slice)")
  1889  					}
  1890  					break
  1891  				}
  1892  				if base.Debug.Append > 0 {
  1893  					base.WarnfAt(n.Pos(), "append: len-only update")
  1894  				}
  1895  				s.append(rhs, true)
  1896  				return
  1897  			}
  1898  		}
  1899  
  1900  		if ir.IsBlank(n.X) {
  1901  			// _ = rhs
  1902  			// Just evaluate rhs for side-effects.
  1903  			if rhs != nil {
  1904  				s.expr(rhs)
  1905  			}
  1906  			return
  1907  		}
  1908  
  1909  		var t *types.Type
  1910  		if n.Y != nil {
  1911  			t = n.Y.Type()
  1912  		} else {
  1913  			t = n.X.Type()
  1914  		}
  1915  
  1916  		var r *ssa.Value
  1917  		deref := !ssa.CanSSA(t)
  1918  		if deref {
  1919  			if rhs == nil {
  1920  				r = nil // Signal assign to use OpZero.
  1921  			} else {
  1922  				r = s.addr(rhs)
  1923  			}
  1924  		} else {
  1925  			if rhs == nil {
  1926  				r = s.zeroVal(t)
  1927  			} else {
  1928  				r = s.expr(rhs)
  1929  			}
  1930  		}
  1931  
  1932  		var skip skipMask
  1933  		if rhs != nil && (rhs.Op() == ir.OSLICE || rhs.Op() == ir.OSLICE3 || rhs.Op() == ir.OSLICESTR) && ir.SameSafeExpr(rhs.(*ir.SliceExpr).X, n.X) {
  1934  			// We're assigning a slicing operation back to its source.
  1935  			// Don't write back fields we aren't changing. See issue #14855.
  1936  			rhs := rhs.(*ir.SliceExpr)
  1937  			i, j, k := rhs.Low, rhs.High, rhs.Max
  1938  			if i != nil && (i.Op() == ir.OLITERAL && i.Val().Kind() == constant.Int && ir.Int64Val(i) == 0) {
  1939  				// [0:...] is the same as [:...]
  1940  				i = nil
  1941  			}
  1942  			// TODO: detect defaults for len/cap also.
  1943  			// Currently doesn't really work because (*p)[:len(*p)] appears here as:
  1944  			//    tmp = len(*p)
  1945  			//    (*p)[:tmp]
  1946  			// if j != nil && (j.Op == OLEN && SameSafeExpr(j.Left, n.Left)) {
  1947  			//      j = nil
  1948  			// }
  1949  			// if k != nil && (k.Op == OCAP && SameSafeExpr(k.Left, n.Left)) {
  1950  			//      k = nil
  1951  			// }
  1952  			if i == nil {
  1953  				skip |= skipPtr
  1954  				if j == nil {
  1955  					skip |= skipLen
  1956  				}
  1957  				if k == nil {
  1958  					skip |= skipCap
  1959  				}
  1960  			}
  1961  		}
  1962  
  1963  		s.assignWhichMayOverlap(n.X, r, deref, skip, mayOverlap)
  1964  
  1965  	case ir.OIF:
  1966  		n := n.(*ir.IfStmt)
  1967  		if ir.IsConst(n.Cond, constant.Bool) {
  1968  			s.stmtList(n.Cond.Init())
  1969  			if ir.BoolVal(n.Cond) {
  1970  				s.stmtList(n.Body)
  1971  			} else {
  1972  				s.stmtList(n.Else)
  1973  			}
  1974  			break
  1975  		}
  1976  
  1977  		bEnd := s.f.NewBlock(block.BlockPlain)
  1978  		var likely int8
  1979  		if n.Likely {
  1980  			likely = 1
  1981  		}
  1982  		var bThen *ssa.Block
  1983  		if len(n.Body) != 0 {
  1984  			bThen = s.f.NewBlock(block.BlockPlain)
  1985  		} else {
  1986  			bThen = bEnd
  1987  		}
  1988  		var bElse *ssa.Block
  1989  		if len(n.Else) != 0 {
  1990  			bElse = s.f.NewBlock(block.BlockPlain)
  1991  		} else {
  1992  			bElse = bEnd
  1993  		}
  1994  		s.condBranch(n.Cond, bThen, bElse, likely)
  1995  
  1996  		if len(n.Body) != 0 {
  1997  			s.startBlock(bThen)
  1998  			s.stmtList(n.Body)
  1999  			if b := s.endBlock(); b != nil {
  2000  				b.AddEdgeTo(bEnd)
  2001  			}
  2002  		}
  2003  		if len(n.Else) != 0 {
  2004  			s.startBlock(bElse)
  2005  			s.stmtList(n.Else)
  2006  			if b := s.endBlock(); b != nil {
  2007  				b.AddEdgeTo(bEnd)
  2008  			}
  2009  		}
  2010  		s.startBlock(bEnd)
  2011  
  2012  	case ir.ORETURN:
  2013  		n := n.(*ir.ReturnStmt)
  2014  		s.stmtList(n.Results)
  2015  		b := s.exit()
  2016  		b.Pos = s.lastPos.WithIsStmt()
  2017  
  2018  	case ir.OTAILCALL:
  2019  		n := n.(*ir.TailCallStmt)
  2020  		s.callResult(n.Call, callTail)
  2021  		call := s.mem()
  2022  		b := s.endBlock()
  2023  		b.Kind = block.BlockRetJmp // could use BlockExit. BlockRetJmp is mostly for clarity.
  2024  		b.SetControl(call)
  2025  
  2026  	case ir.OCONTINUE, ir.OBREAK:
  2027  		n := n.(*ir.BranchStmt)
  2028  		var to *ssa.Block
  2029  		if n.Label == nil {
  2030  			// plain break/continue
  2031  			switch n.Op() {
  2032  			case ir.OCONTINUE:
  2033  				to = s.continueTo
  2034  			case ir.OBREAK:
  2035  				to = s.breakTo
  2036  			}
  2037  		} else {
  2038  			// labeled break/continue; look up the target
  2039  			sym := n.Label
  2040  			lab := s.label(sym)
  2041  			switch n.Op() {
  2042  			case ir.OCONTINUE:
  2043  				to = lab.continueTarget
  2044  			case ir.OBREAK:
  2045  				to = lab.breakTarget
  2046  			}
  2047  		}
  2048  
  2049  		b := s.endBlock()
  2050  		if n.Pos().IsStmt() == src.PosNotStmt {
  2051  			// the front end generated this branch, and it is
  2052  			// not a statement in the source (for example, the
  2053  			// implicit default case of a switch). See issue 81705.
  2054  			b.Pos = s.lastPos.WithNotStmt()
  2055  		} else {
  2056  			b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
  2057  		}
  2058  		b.AddEdgeTo(to)
  2059  
  2060  	case ir.OFOR:
  2061  		// OFOR: for Ninit; Left; Right { Nbody }
  2062  		// cond (Left); body (Nbody); incr (Right)
  2063  		n := n.(*ir.ForStmt)
  2064  		base.Assert(!n.DistinctVars) // Should all be rewritten before escape analysis
  2065  		bCond := s.f.NewBlock(block.BlockPlain)
  2066  		bBody := s.f.NewBlock(block.BlockPlain)
  2067  		bIncr := s.f.NewBlock(block.BlockPlain)
  2068  		bEnd := s.f.NewBlock(block.BlockPlain)
  2069  
  2070  		// ensure empty for loops have correct position; issue #30167
  2071  		bBody.Pos = n.Pos()
  2072  
  2073  		// first, jump to condition test
  2074  		b := s.endBlock()
  2075  		b.AddEdgeTo(bCond)
  2076  
  2077  		// generate code to test condition
  2078  		s.startBlock(bCond)
  2079  		if n.Cond != nil {
  2080  			s.condBranch(n.Cond, bBody, bEnd, 1)
  2081  		} else {
  2082  			b := s.endBlock()
  2083  			b.Kind = block.BlockPlain
  2084  			b.AddEdgeTo(bBody)
  2085  		}
  2086  
  2087  		// set up for continue/break in body
  2088  		prevContinue := s.continueTo
  2089  		prevBreak := s.breakTo
  2090  		s.continueTo = bIncr
  2091  		s.breakTo = bEnd
  2092  		var lab *ssaLabel
  2093  		if sym := n.Label; sym != nil {
  2094  			// labeled for loop
  2095  			lab = s.label(sym)
  2096  			lab.continueTarget = bIncr
  2097  			lab.breakTarget = bEnd
  2098  		}
  2099  
  2100  		// generate body
  2101  		s.startBlock(bBody)
  2102  		s.stmtList(n.Body)
  2103  
  2104  		// tear down continue/break
  2105  		s.continueTo = prevContinue
  2106  		s.breakTo = prevBreak
  2107  		if lab != nil {
  2108  			lab.continueTarget = nil
  2109  			lab.breakTarget = nil
  2110  		}
  2111  
  2112  		// done with body, goto incr
  2113  		if b := s.endBlock(); b != nil {
  2114  			b.AddEdgeTo(bIncr)
  2115  		}
  2116  
  2117  		// generate incr
  2118  		s.startBlock(bIncr)
  2119  		if n.Post != nil {
  2120  			s.stmt(n.Post)
  2121  		}
  2122  		if b := s.endBlock(); b != nil {
  2123  			b.AddEdgeTo(bCond)
  2124  			// It can happen that bIncr ends in a block containing only VARKILL,
  2125  			// and that muddles the debugging experience.
  2126  			if b.Pos == src.NoXPos {
  2127  				b.Pos = bCond.Pos
  2128  			}
  2129  		}
  2130  
  2131  		s.startBlock(bEnd)
  2132  
  2133  	case ir.OSWITCH, ir.OSELECT:
  2134  		// These have been mostly rewritten by the front end into their Nbody fields.
  2135  		// Our main task is to correctly hook up any break statements.
  2136  		bEnd := s.f.NewBlock(block.BlockPlain)
  2137  
  2138  		prevBreak := s.breakTo
  2139  		s.breakTo = bEnd
  2140  		var sym *types.Sym
  2141  		var body ir.Nodes
  2142  		if n.Op() == ir.OSWITCH {
  2143  			n := n.(*ir.SwitchStmt)
  2144  			sym = n.Label
  2145  			body = n.Compiled
  2146  		} else {
  2147  			n := n.(*ir.SelectStmt)
  2148  			sym = n.Label
  2149  			body = n.Compiled
  2150  		}
  2151  
  2152  		var lab *ssaLabel
  2153  		if sym != nil {
  2154  			// labeled
  2155  			lab = s.label(sym)
  2156  			lab.breakTarget = bEnd
  2157  		}
  2158  
  2159  		// End the current block at the position of the switch or select
  2160  		// statement. The jump at the end of the block gives the statement
  2161  		// an instruction that executes before any case is evaluated. In
  2162  		// optimized builds, the empty block is fused away. Without this, a
  2163  		// switch with no tag has no such instruction, and a breakpoint on
  2164  		// the switch line stops only after all cases fail. See issue 81705.
  2165  		if s.curBlock != nil && n.Pos().IsStmt() != src.PosNotStmt {
  2166  			b := s.endBlock()
  2167  			b.Pos = n.Pos().WithIsStmt()
  2168  			bStart := s.f.NewBlock(block.BlockPlain)
  2169  			b.AddEdgeTo(bStart)
  2170  			s.startBlock(bStart)
  2171  		}
  2172  
  2173  		// generate body code
  2174  		s.stmtList(body)
  2175  
  2176  		s.breakTo = prevBreak
  2177  		if lab != nil {
  2178  			lab.breakTarget = nil
  2179  		}
  2180  
  2181  		// walk adds explicit OBREAK nodes to the end of all reachable code paths.
  2182  		// If we still have a current block here, then mark it unreachable.
  2183  		if s.curBlock != nil {
  2184  			m := s.mem()
  2185  			b := s.endBlock()
  2186  			b.Kind = block.BlockExit
  2187  			b.SetControl(m)
  2188  		}
  2189  		s.startBlock(bEnd)
  2190  
  2191  	case ir.OJUMPTABLE:
  2192  		n := n.(*ir.JumpTableStmt)
  2193  
  2194  		// Make blocks we'll need.
  2195  		jt := s.f.NewBlock(block.BlockJumpTable)
  2196  		bEnd := s.f.NewBlock(block.BlockPlain)
  2197  
  2198  		// The only thing that needs evaluating is the index we're looking up.
  2199  		idx := s.expr(n.Idx)
  2200  		unsigned := idx.Type.IsUnsigned()
  2201  
  2202  		// Extend so we can do everything in uintptr arithmetic.
  2203  		t := types.Types[types.TUINTPTR]
  2204  		idx = s.conv(nil, idx, idx.Type, t)
  2205  
  2206  		// The ending condition for the current block decides whether we'll use
  2207  		// the jump table at all.
  2208  		// We check that min <= idx <= max and jump around the jump table
  2209  		// if that test fails.
  2210  		// We implement min <= idx <= max with 0 <= idx-min <= max-min, because
  2211  		// we'll need idx-min anyway as the control value for the jump table.
  2212  		var min, max uint64
  2213  		if unsigned {
  2214  			min, _ = constant.Uint64Val(n.Cases[0])
  2215  			max, _ = constant.Uint64Val(n.Cases[len(n.Cases)-1])
  2216  		} else {
  2217  			mn, _ := constant.Int64Val(n.Cases[0])
  2218  			mx, _ := constant.Int64Val(n.Cases[len(n.Cases)-1])
  2219  			min = uint64(mn)
  2220  			max = uint64(mx)
  2221  		}
  2222  		// Compare idx-min with max-min, to see if we can use the jump table.
  2223  		idx = s.newValue2(s.ssaOp(ir.OSUB, t), t, idx, s.uintptrConstant(min))
  2224  		width := s.uintptrConstant(max - min)
  2225  		cmp := s.newValue2(s.ssaOp(ir.OLE, t), types.Types[types.TBOOL], idx, width)
  2226  		b := s.endBlock()
  2227  		b.Kind = block.BlockIf
  2228  		b.SetControl(cmp)
  2229  		b.AddEdgeTo(jt)             // in range - use jump table
  2230  		b.AddEdgeTo(bEnd)           // out of range - no case in the jump table will trigger
  2231  		b.Likely = ssa.BranchLikely // TODO: assumes missing the table entirely is unlikely. True?
  2232  
  2233  		// Build jump table block.
  2234  		s.startBlock(jt)
  2235  		jt.Pos = n.Pos()
  2236  		if base.Flag.Cfg.SpectreIndex {
  2237  			idx = s.newValue2(ssaop.OpSpectreSliceIndex, t, idx, width)
  2238  		}
  2239  		jt.SetControl(idx)
  2240  
  2241  		// Figure out where we should go for each index in the table.
  2242  		table := make([]*ssa.Block, max-min+1)
  2243  		for i := range table {
  2244  			table[i] = bEnd // default target
  2245  		}
  2246  		for i := range n.Targets {
  2247  			c := n.Cases[i]
  2248  			lab := s.label(n.Targets[i])
  2249  			if lab.target == nil {
  2250  				lab.target = s.f.NewBlock(block.BlockPlain)
  2251  			}
  2252  			var val uint64
  2253  			if unsigned {
  2254  				val, _ = constant.Uint64Val(c)
  2255  			} else {
  2256  				vl, _ := constant.Int64Val(c)
  2257  				val = uint64(vl)
  2258  			}
  2259  			// Overwrite the default target.
  2260  			table[val-min] = lab.target
  2261  		}
  2262  		for _, t := range table {
  2263  			jt.AddEdgeTo(t)
  2264  		}
  2265  		s.endBlock()
  2266  
  2267  		s.startBlock(bEnd)
  2268  
  2269  	case ir.OINTERFACESWITCH:
  2270  		n := n.(*ir.InterfaceSwitchStmt)
  2271  		typs := s.f.Config.Types
  2272  
  2273  		t := s.expr(n.RuntimeType)
  2274  		h := s.expr(n.Hash)
  2275  		d := s.newValue1A(ssaop.OpAddr, typs.BytePtr, n.Descriptor, s.sb)
  2276  
  2277  		// Check the cache first.
  2278  		var merge *ssa.Block
  2279  		if base.Flag.N == 0 && rtabi.UseInterfaceSwitchCache(Arch.LinkArch.Family) {
  2280  			// Note: we can only use the cache if we have the right atomic load instruction.
  2281  			// Double-check that here.
  2282  			if intrinsics.lookup(Arch.LinkArch.Arch, "internal/runtime/atomic", "Loadp") == nil {
  2283  				s.Fatalf("atomic load not available")
  2284  			}
  2285  			merge = s.f.NewBlock(block.BlockPlain)
  2286  			cacheHit := s.f.NewBlock(block.BlockPlain)
  2287  			cacheMiss := s.f.NewBlock(block.BlockPlain)
  2288  			loopHead := s.f.NewBlock(block.BlockPlain)
  2289  			loopBody := s.f.NewBlock(block.BlockPlain)
  2290  
  2291  			// Pick right size ops.
  2292  			var mul, and, add, zext ssaop.Op
  2293  			if s.config.PtrSize == 4 {
  2294  				mul = ssaop.OpMul32
  2295  				and = ssaop.OpAnd32
  2296  				add = ssaop.OpAdd32
  2297  				zext = ssaop.OpCopy
  2298  			} else {
  2299  				mul = ssaop.OpMul64
  2300  				and = ssaop.OpAnd64
  2301  				add = ssaop.OpAdd64
  2302  				zext = ssaop.OpZeroExt32to64
  2303  			}
  2304  
  2305  			// Load cache pointer out of descriptor, with an atomic load so
  2306  			// we ensure that we see a fully written cache.
  2307  			atomicLoad := s.newValue2(ssaop.OpAtomicLoadPtr, types.NewTuple(typs.BytePtr, types.TypeMem), d, s.mem())
  2308  			cache := s.newValue1(ssaop.OpSelect0, typs.BytePtr, atomicLoad)
  2309  			s.vars[memVar] = s.newValue1(ssaop.OpSelect1, types.TypeMem, atomicLoad)
  2310  
  2311  			// Initialize hash variable.
  2312  			s.vars[hashVar] = s.newValue1(zext, typs.Uintptr, h)
  2313  
  2314  			// Load mask from cache.
  2315  			mask := s.newValue2(ssaop.OpLoad, typs.Uintptr, cache, s.mem())
  2316  			// Jump to loop head.
  2317  			b := s.endBlock()
  2318  			b.AddEdgeTo(loopHead)
  2319  
  2320  			// At loop head, get pointer to the cache entry.
  2321  			//   e := &cache.Entries[hash&mask]
  2322  			s.startBlock(loopHead)
  2323  			entries := s.newValue2(ssaop.OpAddPtr, typs.UintptrPtr, cache, s.uintptrConstant(uint64(s.config.PtrSize)))
  2324  			idx := s.newValue2(and, typs.Uintptr, s.variable(hashVar, typs.Uintptr), mask)
  2325  			idx = s.newValue2(mul, typs.Uintptr, idx, s.uintptrConstant(uint64(3*s.config.PtrSize)))
  2326  			e := s.newValue2(ssaop.OpAddPtr, typs.UintptrPtr, entries, idx)
  2327  			//   hash++
  2328  			s.vars[hashVar] = s.newValue2(add, typs.Uintptr, s.variable(hashVar, typs.Uintptr), s.uintptrConstant(1))
  2329  
  2330  			// Look for a cache hit.
  2331  			//   if e.Typ == t { goto hit }
  2332  			eTyp := s.newValue2(ssaop.OpLoad, typs.Uintptr, e, s.mem())
  2333  			cmp1 := s.newValue2(ssaop.OpEqPtr, typs.Bool, t, eTyp)
  2334  			b = s.endBlock()
  2335  			b.Kind = block.BlockIf
  2336  			b.SetControl(cmp1)
  2337  			b.AddEdgeTo(cacheHit)
  2338  			b.AddEdgeTo(loopBody)
  2339  
  2340  			// Look for an empty entry, the tombstone for this hash table.
  2341  			//   if e.Typ == nil { goto miss }
  2342  			s.startBlock(loopBody)
  2343  			cmp2 := s.newValue2(ssaop.OpEqPtr, typs.Bool, eTyp, s.constNil(typs.BytePtr))
  2344  			b = s.endBlock()
  2345  			b.Kind = block.BlockIf
  2346  			b.SetControl(cmp2)
  2347  			b.AddEdgeTo(cacheMiss)
  2348  			b.AddEdgeTo(loopHead)
  2349  
  2350  			// On a hit, load the data fields of the cache entry.
  2351  			//   Case = e.Case
  2352  			//   Itab = e.Itab
  2353  			s.startBlock(cacheHit)
  2354  			eCase := s.newValue2(ssaop.OpLoad, typs.Int, s.newValue1I(ssaop.OpOffPtr, typs.IntPtr, s.config.PtrSize, e), s.mem())
  2355  			eItab := s.newValue2(ssaop.OpLoad, typs.BytePtr, s.newValue1I(ssaop.OpOffPtr, typs.BytePtrPtr, 2*s.config.PtrSize, e), s.mem())
  2356  			s.assign(n.Case, eCase, false, 0)
  2357  			s.assign(n.Itab, eItab, false, 0)
  2358  			b = s.endBlock()
  2359  			b.AddEdgeTo(merge)
  2360  
  2361  			// On a miss, call into the runtime to get the answer.
  2362  			s.startBlock(cacheMiss)
  2363  		}
  2364  
  2365  		r := s.rtcall(ir.Syms.InterfaceSwitch, true, []*types.Type{typs.Int, typs.BytePtr}, d, t)
  2366  		s.assign(n.Case, r[0], false, 0)
  2367  		s.assign(n.Itab, r[1], false, 0)
  2368  
  2369  		if merge != nil {
  2370  			// Cache hits merge in here.
  2371  			b := s.endBlock()
  2372  			b.Kind = block.BlockPlain
  2373  			b.AddEdgeTo(merge)
  2374  			s.startBlock(merge)
  2375  		}
  2376  
  2377  	case ir.OCHECKNIL:
  2378  		n := n.(*ir.UnaryExpr)
  2379  		p := s.expr(n.X)
  2380  		_ = s.nilCheck(p)
  2381  		// TODO: check that throwing away the nilcheck result is ok.
  2382  
  2383  	case ir.OINLMARK:
  2384  		n := n.(*ir.InlineMarkStmt)
  2385  		s.newValue1I(ssaop.OpInlMark, types.TypeVoid, n.Index, s.mem())
  2386  
  2387  	default:
  2388  		s.Fatalf("unhandled stmt %v", n.Op())
  2389  	}
  2390  }
  2391  
  2392  // If true, share as many open-coded defer exits as possible (with the downside of
  2393  // worse line-number information)
  2394  const shareDeferExits = false
  2395  
  2396  // exit processes any code that needs to be generated just before returning.
  2397  // It returns a BlockRet block that ends the control flow. Its control value
  2398  // will be set to the final memory state.
  2399  func (s *state) exit() *ssa.Block {
  2400  	if s.hasdefer {
  2401  		if s.hasOpenDefers {
  2402  			if shareDeferExits && s.lastDeferExit != nil && len(s.openDefers) == s.lastDeferCount {
  2403  				if s.curBlock.Kind != block.BlockPlain {
  2404  					panic("Block for an exit should be BlockPlain")
  2405  				}
  2406  				s.curBlock.AddEdgeTo(s.lastDeferExit)
  2407  				s.endBlock()
  2408  				return s.lastDeferFinalBlock
  2409  			}
  2410  			s.openDeferExit()
  2411  		} else {
  2412  			// Shared deferreturn is assigned the "last" position in the function.
  2413  			// The linker picks the first deferreturn call it sees, so this is
  2414  			// the only sensible "shared" place.
  2415  			// To not-share deferreturn, the protocol would need to be changed
  2416  			// so that the call to deferproc-etc would receive the PC offset from
  2417  			// the return PC, and the runtime would need to use that instead of
  2418  			// the deferreturn retrieved from the pcln information.
  2419  			// opendefers would remain a problem, however.
  2420  			s.pushLine(s.curfn.Endlineno)
  2421  			s.rtcall(ir.Syms.Deferreturn, true, nil)
  2422  			s.popLine()
  2423  		}
  2424  	}
  2425  
  2426  	// Do actual return.
  2427  	// These currently turn into self-copies (in many cases).
  2428  	resultFields := s.curfn.Type().Results()
  2429  	results := make([]*ssa.Value, len(resultFields)+1, len(resultFields)+1)
  2430  	// Store SSAable and heap-escaped PPARAMOUT variables back to stack locations.
  2431  	for i, f := range resultFields {
  2432  		n := f.Nname.(*ir.Name)
  2433  		if s.canSSA(n) { // result is in some SSA variable
  2434  			if !n.IsOutputParamInRegisters() && n.Type().HasPointers() {
  2435  				// We are about to store to the result slot.
  2436  				s.vars[memVar] = s.newValue1A(ssaop.OpVarDef, types.TypeMem, n, s.mem())
  2437  			}
  2438  			results[i] = s.variable(n, n.Type())
  2439  		} else if !n.OnStack() { // result is actually heap allocated
  2440  			// We are about to copy the in-heap result to the result slot.
  2441  			if n.Type().HasPointers() {
  2442  				s.vars[memVar] = s.newValue1A(ssaop.OpVarDef, types.TypeMem, n, s.mem())
  2443  			}
  2444  			ha := s.expr(n.Heapaddr)
  2445  			s.instrumentFields(n.Type(), ha, instrumentRead)
  2446  			results[i] = s.newValue2(ssaop.OpDereference, n.Type(), ha, s.mem())
  2447  		} else { // result is not SSA-able; not escaped, so not on heap, but too large for SSA.
  2448  			// Before register ABI this ought to be a self-move, home=dest,
  2449  			// With register ABI, it's still a self-move if parameter is on stack (i.e., too big or overflowed)
  2450  			// No VarDef, as the result slot is already holding live value.
  2451  			results[i] = s.newValue2(ssaop.OpDereference, n.Type(), s.addr(n), s.mem())
  2452  		}
  2453  	}
  2454  
  2455  	// In -race mode, we need to call racefuncexit.
  2456  	// Note: This has to happen after we load any heap-allocated results,
  2457  	// otherwise races will be attributed to the caller instead.
  2458  	if s.instrumentEnterExit {
  2459  		s.rtcall(ir.Syms.Racefuncexit, true, nil)
  2460  	}
  2461  
  2462  	results[len(results)-1] = s.mem()
  2463  	m := s.newValue0(ssaop.OpMakeResult, s.f.OwnAux.LateExpansionResultType())
  2464  	m.AddArgs(results...)
  2465  
  2466  	b := s.endBlock()
  2467  	b.Kind = block.BlockRet
  2468  	b.SetControl(m)
  2469  	if s.hasdefer && s.hasOpenDefers {
  2470  		s.lastDeferFinalBlock = b
  2471  	}
  2472  	return b
  2473  }
  2474  
  2475  type opAndType struct {
  2476  	op    ir.Op
  2477  	etype types.Kind
  2478  }
  2479  
  2480  var opToSSA = map[opAndType]ssaop.Op{
  2481  	{ir.OADD, types.TINT8}:    ssaop.OpAdd8,
  2482  	{ir.OADD, types.TUINT8}:   ssaop.OpAdd8,
  2483  	{ir.OADD, types.TINT16}:   ssaop.OpAdd16,
  2484  	{ir.OADD, types.TUINT16}:  ssaop.OpAdd16,
  2485  	{ir.OADD, types.TINT32}:   ssaop.OpAdd32,
  2486  	{ir.OADD, types.TUINT32}:  ssaop.OpAdd32,
  2487  	{ir.OADD, types.TINT64}:   ssaop.OpAdd64,
  2488  	{ir.OADD, types.TUINT64}:  ssaop.OpAdd64,
  2489  	{ir.OADD, types.TFLOAT32}: ssaop.OpAdd32F,
  2490  	{ir.OADD, types.TFLOAT64}: ssaop.OpAdd64F,
  2491  
  2492  	{ir.OSUB, types.TINT8}:    ssaop.OpSub8,
  2493  	{ir.OSUB, types.TUINT8}:   ssaop.OpSub8,
  2494  	{ir.OSUB, types.TINT16}:   ssaop.OpSub16,
  2495  	{ir.OSUB, types.TUINT16}:  ssaop.OpSub16,
  2496  	{ir.OSUB, types.TINT32}:   ssaop.OpSub32,
  2497  	{ir.OSUB, types.TUINT32}:  ssaop.OpSub32,
  2498  	{ir.OSUB, types.TINT64}:   ssaop.OpSub64,
  2499  	{ir.OSUB, types.TUINT64}:  ssaop.OpSub64,
  2500  	{ir.OSUB, types.TFLOAT32}: ssaop.OpSub32F,
  2501  	{ir.OSUB, types.TFLOAT64}: ssaop.OpSub64F,
  2502  
  2503  	{ir.ONOT, types.TBOOL}: ssaop.OpNot,
  2504  
  2505  	{ir.ONEG, types.TINT8}:    ssaop.OpNeg8,
  2506  	{ir.ONEG, types.TUINT8}:   ssaop.OpNeg8,
  2507  	{ir.ONEG, types.TINT16}:   ssaop.OpNeg16,
  2508  	{ir.ONEG, types.TUINT16}:  ssaop.OpNeg16,
  2509  	{ir.ONEG, types.TINT32}:   ssaop.OpNeg32,
  2510  	{ir.ONEG, types.TUINT32}:  ssaop.OpNeg32,
  2511  	{ir.ONEG, types.TINT64}:   ssaop.OpNeg64,
  2512  	{ir.ONEG, types.TUINT64}:  ssaop.OpNeg64,
  2513  	{ir.ONEG, types.TFLOAT32}: ssaop.OpNeg32F,
  2514  	{ir.ONEG, types.TFLOAT64}: ssaop.OpNeg64F,
  2515  
  2516  	{ir.OBITNOT, types.TINT8}:   ssaop.OpCom8,
  2517  	{ir.OBITNOT, types.TUINT8}:  ssaop.OpCom8,
  2518  	{ir.OBITNOT, types.TINT16}:  ssaop.OpCom16,
  2519  	{ir.OBITNOT, types.TUINT16}: ssaop.OpCom16,
  2520  	{ir.OBITNOT, types.TINT32}:  ssaop.OpCom32,
  2521  	{ir.OBITNOT, types.TUINT32}: ssaop.OpCom32,
  2522  	{ir.OBITNOT, types.TINT64}:  ssaop.OpCom64,
  2523  	{ir.OBITNOT, types.TUINT64}: ssaop.OpCom64,
  2524  
  2525  	{ir.OIMAG, types.TCOMPLEX64}:  ssaop.OpComplexImag,
  2526  	{ir.OIMAG, types.TCOMPLEX128}: ssaop.OpComplexImag,
  2527  	{ir.OREAL, types.TCOMPLEX64}:  ssaop.OpComplexReal,
  2528  	{ir.OREAL, types.TCOMPLEX128}: ssaop.OpComplexReal,
  2529  
  2530  	{ir.OMUL, types.TINT8}:    ssaop.OpMul8,
  2531  	{ir.OMUL, types.TUINT8}:   ssaop.OpMul8,
  2532  	{ir.OMUL, types.TINT16}:   ssaop.OpMul16,
  2533  	{ir.OMUL, types.TUINT16}:  ssaop.OpMul16,
  2534  	{ir.OMUL, types.TINT32}:   ssaop.OpMul32,
  2535  	{ir.OMUL, types.TUINT32}:  ssaop.OpMul32,
  2536  	{ir.OMUL, types.TINT64}:   ssaop.OpMul64,
  2537  	{ir.OMUL, types.TUINT64}:  ssaop.OpMul64,
  2538  	{ir.OMUL, types.TFLOAT32}: ssaop.OpMul32F,
  2539  	{ir.OMUL, types.TFLOAT64}: ssaop.OpMul64F,
  2540  
  2541  	{ir.ODIV, types.TFLOAT32}: ssaop.OpDiv32F,
  2542  	{ir.ODIV, types.TFLOAT64}: ssaop.OpDiv64F,
  2543  
  2544  	{ir.ODIV, types.TINT8}:   ssaop.OpDiv8,
  2545  	{ir.ODIV, types.TUINT8}:  ssaop.OpDiv8u,
  2546  	{ir.ODIV, types.TINT16}:  ssaop.OpDiv16,
  2547  	{ir.ODIV, types.TUINT16}: ssaop.OpDiv16u,
  2548  	{ir.ODIV, types.TINT32}:  ssaop.OpDiv32,
  2549  	{ir.ODIV, types.TUINT32}: ssaop.OpDiv32u,
  2550  	{ir.ODIV, types.TINT64}:  ssaop.OpDiv64,
  2551  	{ir.ODIV, types.TUINT64}: ssaop.OpDiv64u,
  2552  
  2553  	{ir.OMOD, types.TINT8}:   ssaop.OpMod8,
  2554  	{ir.OMOD, types.TUINT8}:  ssaop.OpMod8u,
  2555  	{ir.OMOD, types.TINT16}:  ssaop.OpMod16,
  2556  	{ir.OMOD, types.TUINT16}: ssaop.OpMod16u,
  2557  	{ir.OMOD, types.TINT32}:  ssaop.OpMod32,
  2558  	{ir.OMOD, types.TUINT32}: ssaop.OpMod32u,
  2559  	{ir.OMOD, types.TINT64}:  ssaop.OpMod64,
  2560  	{ir.OMOD, types.TUINT64}: ssaop.OpMod64u,
  2561  
  2562  	{ir.OAND, types.TINT8}:   ssaop.OpAnd8,
  2563  	{ir.OAND, types.TUINT8}:  ssaop.OpAnd8,
  2564  	{ir.OAND, types.TINT16}:  ssaop.OpAnd16,
  2565  	{ir.OAND, types.TUINT16}: ssaop.OpAnd16,
  2566  	{ir.OAND, types.TINT32}:  ssaop.OpAnd32,
  2567  	{ir.OAND, types.TUINT32}: ssaop.OpAnd32,
  2568  	{ir.OAND, types.TINT64}:  ssaop.OpAnd64,
  2569  	{ir.OAND, types.TUINT64}: ssaop.OpAnd64,
  2570  
  2571  	{ir.OOR, types.TINT8}:   ssaop.OpOr8,
  2572  	{ir.OOR, types.TUINT8}:  ssaop.OpOr8,
  2573  	{ir.OOR, types.TINT16}:  ssaop.OpOr16,
  2574  	{ir.OOR, types.TUINT16}: ssaop.OpOr16,
  2575  	{ir.OOR, types.TINT32}:  ssaop.OpOr32,
  2576  	{ir.OOR, types.TUINT32}: ssaop.OpOr32,
  2577  	{ir.OOR, types.TINT64}:  ssaop.OpOr64,
  2578  	{ir.OOR, types.TUINT64}: ssaop.OpOr64,
  2579  
  2580  	{ir.OXOR, types.TINT8}:   ssaop.OpXor8,
  2581  	{ir.OXOR, types.TUINT8}:  ssaop.OpXor8,
  2582  	{ir.OXOR, types.TINT16}:  ssaop.OpXor16,
  2583  	{ir.OXOR, types.TUINT16}: ssaop.OpXor16,
  2584  	{ir.OXOR, types.TINT32}:  ssaop.OpXor32,
  2585  	{ir.OXOR, types.TUINT32}: ssaop.OpXor32,
  2586  	{ir.OXOR, types.TINT64}:  ssaop.OpXor64,
  2587  	{ir.OXOR, types.TUINT64}: ssaop.OpXor64,
  2588  
  2589  	{ir.OEQ, types.TBOOL}:      ssaop.OpEqB,
  2590  	{ir.OEQ, types.TINT8}:      ssaop.OpEq8,
  2591  	{ir.OEQ, types.TUINT8}:     ssaop.OpEq8,
  2592  	{ir.OEQ, types.TINT16}:     ssaop.OpEq16,
  2593  	{ir.OEQ, types.TUINT16}:    ssaop.OpEq16,
  2594  	{ir.OEQ, types.TINT32}:     ssaop.OpEq32,
  2595  	{ir.OEQ, types.TUINT32}:    ssaop.OpEq32,
  2596  	{ir.OEQ, types.TINT64}:     ssaop.OpEq64,
  2597  	{ir.OEQ, types.TUINT64}:    ssaop.OpEq64,
  2598  	{ir.OEQ, types.TINTER}:     ssaop.OpEqInter,
  2599  	{ir.OEQ, types.TSLICE}:     ssaop.OpEqSlice,
  2600  	{ir.OEQ, types.TFUNC}:      ssaop.OpEqPtr,
  2601  	{ir.OEQ, types.TMAP}:       ssaop.OpEqPtr,
  2602  	{ir.OEQ, types.TCHAN}:      ssaop.OpEqPtr,
  2603  	{ir.OEQ, types.TPTR}:       ssaop.OpEqPtr,
  2604  	{ir.OEQ, types.TUINTPTR}:   ssaop.OpEqPtr,
  2605  	{ir.OEQ, types.TUNSAFEPTR}: ssaop.OpEqPtr,
  2606  	{ir.OEQ, types.TFLOAT64}:   ssaop.OpEq64F,
  2607  	{ir.OEQ, types.TFLOAT32}:   ssaop.OpEq32F,
  2608  
  2609  	{ir.ONE, types.TBOOL}:      ssaop.OpNeqB,
  2610  	{ir.ONE, types.TINT8}:      ssaop.OpNeq8,
  2611  	{ir.ONE, types.TUINT8}:     ssaop.OpNeq8,
  2612  	{ir.ONE, types.TINT16}:     ssaop.OpNeq16,
  2613  	{ir.ONE, types.TUINT16}:    ssaop.OpNeq16,
  2614  	{ir.ONE, types.TINT32}:     ssaop.OpNeq32,
  2615  	{ir.ONE, types.TUINT32}:    ssaop.OpNeq32,
  2616  	{ir.ONE, types.TINT64}:     ssaop.OpNeq64,
  2617  	{ir.ONE, types.TUINT64}:    ssaop.OpNeq64,
  2618  	{ir.ONE, types.TINTER}:     ssaop.OpNeqInter,
  2619  	{ir.ONE, types.TSLICE}:     ssaop.OpNeqSlice,
  2620  	{ir.ONE, types.TFUNC}:      ssaop.OpNeqPtr,
  2621  	{ir.ONE, types.TMAP}:       ssaop.OpNeqPtr,
  2622  	{ir.ONE, types.TCHAN}:      ssaop.OpNeqPtr,
  2623  	{ir.ONE, types.TPTR}:       ssaop.OpNeqPtr,
  2624  	{ir.ONE, types.TUINTPTR}:   ssaop.OpNeqPtr,
  2625  	{ir.ONE, types.TUNSAFEPTR}: ssaop.OpNeqPtr,
  2626  	{ir.ONE, types.TFLOAT64}:   ssaop.OpNeq64F,
  2627  	{ir.ONE, types.TFLOAT32}:   ssaop.OpNeq32F,
  2628  
  2629  	{ir.OLT, types.TINT8}:    ssaop.OpLess8,
  2630  	{ir.OLT, types.TUINT8}:   ssaop.OpLess8U,
  2631  	{ir.OLT, types.TINT16}:   ssaop.OpLess16,
  2632  	{ir.OLT, types.TUINT16}:  ssaop.OpLess16U,
  2633  	{ir.OLT, types.TINT32}:   ssaop.OpLess32,
  2634  	{ir.OLT, types.TUINT32}:  ssaop.OpLess32U,
  2635  	{ir.OLT, types.TINT64}:   ssaop.OpLess64,
  2636  	{ir.OLT, types.TUINT64}:  ssaop.OpLess64U,
  2637  	{ir.OLT, types.TFLOAT64}: ssaop.OpLess64F,
  2638  	{ir.OLT, types.TFLOAT32}: ssaop.OpLess32F,
  2639  
  2640  	{ir.OLE, types.TINT8}:    ssaop.OpLeq8,
  2641  	{ir.OLE, types.TUINT8}:   ssaop.OpLeq8U,
  2642  	{ir.OLE, types.TINT16}:   ssaop.OpLeq16,
  2643  	{ir.OLE, types.TUINT16}:  ssaop.OpLeq16U,
  2644  	{ir.OLE, types.TINT32}:   ssaop.OpLeq32,
  2645  	{ir.OLE, types.TUINT32}:  ssaop.OpLeq32U,
  2646  	{ir.OLE, types.TINT64}:   ssaop.OpLeq64,
  2647  	{ir.OLE, types.TUINT64}:  ssaop.OpLeq64U,
  2648  	{ir.OLE, types.TFLOAT64}: ssaop.OpLeq64F,
  2649  	{ir.OLE, types.TFLOAT32}: ssaop.OpLeq32F,
  2650  }
  2651  
  2652  func (s *state) concreteEtype(t *types.Type) types.Kind {
  2653  	e := t.Kind()
  2654  	switch e {
  2655  	default:
  2656  		return e
  2657  	case types.TINT:
  2658  		if s.config.PtrSize == 8 {
  2659  			return types.TINT64
  2660  		}
  2661  		return types.TINT32
  2662  	case types.TUINT:
  2663  		if s.config.PtrSize == 8 {
  2664  			return types.TUINT64
  2665  		}
  2666  		return types.TUINT32
  2667  	case types.TUINTPTR:
  2668  		if s.config.PtrSize == 8 {
  2669  			return types.TUINT64
  2670  		}
  2671  		return types.TUINT32
  2672  	}
  2673  }
  2674  
  2675  func (s *state) ssaOp(op ir.Op, t *types.Type) ssaop.Op {
  2676  	etype := s.concreteEtype(t)
  2677  	x, ok := opToSSA[opAndType{op, etype}]
  2678  	if !ok {
  2679  		s.Fatalf("unhandled binary op %v %s", op, etype)
  2680  	}
  2681  	return x
  2682  }
  2683  
  2684  type opAndTwoTypes struct {
  2685  	op     ir.Op
  2686  	etype1 types.Kind
  2687  	etype2 types.Kind
  2688  }
  2689  
  2690  type twoTypes struct {
  2691  	etype1 types.Kind
  2692  	etype2 types.Kind
  2693  }
  2694  
  2695  type twoOpsAndType struct {
  2696  	op1              ssaop.Op
  2697  	op2              ssaop.Op
  2698  	intermediateType types.Kind
  2699  }
  2700  
  2701  var fpConvOpToSSA = map[twoTypes]twoOpsAndType{
  2702  
  2703  	{types.TINT8, types.TFLOAT32}:  {ssaop.OpSignExt8to32, ssaop.OpCvt32to32F, types.TINT32},
  2704  	{types.TINT16, types.TFLOAT32}: {ssaop.OpSignExt16to32, ssaop.OpCvt32to32F, types.TINT32},
  2705  	{types.TINT32, types.TFLOAT32}: {ssaop.OpCopy, ssaop.OpCvt32to32F, types.TINT32},
  2706  	{types.TINT64, types.TFLOAT32}: {ssaop.OpCopy, ssaop.OpCvt64to32F, types.TINT64},
  2707  
  2708  	{types.TINT8, types.TFLOAT64}:  {ssaop.OpSignExt8to32, ssaop.OpCvt32to64F, types.TINT32},
  2709  	{types.TINT16, types.TFLOAT64}: {ssaop.OpSignExt16to32, ssaop.OpCvt32to64F, types.TINT32},
  2710  	{types.TINT32, types.TFLOAT64}: {ssaop.OpCopy, ssaop.OpCvt32to64F, types.TINT32},
  2711  	{types.TINT64, types.TFLOAT64}: {ssaop.OpCopy, ssaop.OpCvt64to64F, types.TINT64},
  2712  
  2713  	{types.TFLOAT32, types.TINT8}:  {ssaop.OpCvt32Fto32, ssaop.OpTrunc32to8, types.TINT32},
  2714  	{types.TFLOAT32, types.TINT16}: {ssaop.OpCvt32Fto32, ssaop.OpTrunc32to16, types.TINT32},
  2715  	{types.TFLOAT32, types.TINT32}: {ssaop.OpCvt32Fto32, ssaop.OpCopy, types.TINT32},
  2716  	{types.TFLOAT32, types.TINT64}: {ssaop.OpCvt32Fto64, ssaop.OpCopy, types.TINT64},
  2717  
  2718  	{types.TFLOAT64, types.TINT8}:  {ssaop.OpCvt64Fto32, ssaop.OpTrunc32to8, types.TINT32},
  2719  	{types.TFLOAT64, types.TINT16}: {ssaop.OpCvt64Fto32, ssaop.OpTrunc32to16, types.TINT32},
  2720  	{types.TFLOAT64, types.TINT32}: {ssaop.OpCvt64Fto32, ssaop.OpCopy, types.TINT32},
  2721  	{types.TFLOAT64, types.TINT64}: {ssaop.OpCvt64Fto64, ssaop.OpCopy, types.TINT64},
  2722  	// unsigned
  2723  	{types.TUINT8, types.TFLOAT32}:  {ssaop.OpZeroExt8to32, ssaop.OpCvt32to32F, types.TINT32},
  2724  	{types.TUINT16, types.TFLOAT32}: {ssaop.OpZeroExt16to32, ssaop.OpCvt32to32F, types.TINT32},
  2725  	{types.TUINT32, types.TFLOAT32}: {ssaop.OpZeroExt32to64, ssaop.OpCvt64to32F, types.TINT64}, // go wide to dodge unsigned
  2726  	{types.TUINT64, types.TFLOAT32}: {ssaop.OpCopy, ssaop.OpInvalid, types.TUINT64},            // Cvt64Uto32F, branchy code expansion instead
  2727  
  2728  	{types.TUINT8, types.TFLOAT64}:  {ssaop.OpZeroExt8to32, ssaop.OpCvt32to64F, types.TINT32},
  2729  	{types.TUINT16, types.TFLOAT64}: {ssaop.OpZeroExt16to32, ssaop.OpCvt32to64F, types.TINT32},
  2730  	{types.TUINT32, types.TFLOAT64}: {ssaop.OpZeroExt32to64, ssaop.OpCvt64to64F, types.TINT64}, // go wide to dodge unsigned
  2731  	{types.TUINT64, types.TFLOAT64}: {ssaop.OpCopy, ssaop.OpInvalid, types.TUINT64},            // Cvt64Uto64F, branchy code expansion instead
  2732  
  2733  	{types.TFLOAT32, types.TUINT8}:  {ssaop.OpCvt32Fto32, ssaop.OpTrunc32to8, types.TINT32},
  2734  	{types.TFLOAT32, types.TUINT16}: {ssaop.OpCvt32Fto32, ssaop.OpTrunc32to16, types.TINT32},
  2735  	{types.TFLOAT32, types.TUINT32}: {ssaop.OpInvalid, ssaop.OpCopy, types.TINT64},  // Cvt64Fto32U, branchy code expansion instead
  2736  	{types.TFLOAT32, types.TUINT64}: {ssaop.OpInvalid, ssaop.OpCopy, types.TUINT64}, // Cvt32Fto64U, branchy code expansion instead
  2737  
  2738  	{types.TFLOAT64, types.TUINT8}:  {ssaop.OpCvt64Fto32, ssaop.OpTrunc32to8, types.TINT32},
  2739  	{types.TFLOAT64, types.TUINT16}: {ssaop.OpCvt64Fto32, ssaop.OpTrunc32to16, types.TINT32},
  2740  	{types.TFLOAT64, types.TUINT32}: {ssaop.OpInvalid, ssaop.OpCopy, types.TINT64},  // Cvt64Fto32U, branchy code expansion instead
  2741  	{types.TFLOAT64, types.TUINT64}: {ssaop.OpInvalid, ssaop.OpCopy, types.TUINT64}, // Cvt64Fto64U, branchy code expansion instead
  2742  
  2743  	// float
  2744  	{types.TFLOAT64, types.TFLOAT32}: {ssaop.OpCvt64Fto32F, ssaop.OpCopy, types.TFLOAT32},
  2745  	{types.TFLOAT64, types.TFLOAT64}: {ssaop.OpRound64F, ssaop.OpCopy, types.TFLOAT64},
  2746  	{types.TFLOAT32, types.TFLOAT32}: {ssaop.OpRound32F, ssaop.OpCopy, types.TFLOAT32},
  2747  	{types.TFLOAT32, types.TFLOAT64}: {ssaop.OpCvt32Fto64F, ssaop.OpCopy, types.TFLOAT64},
  2748  }
  2749  
  2750  // this map is used only for 32-bit arch, and only includes the difference
  2751  // on 32-bit arch, don't use int64<->float conversion for uint32
  2752  var fpConvOpToSSA32 = map[twoTypes]twoOpsAndType{
  2753  	{types.TUINT32, types.TFLOAT32}: {ssaop.OpCopy, ssaop.OpCvt32Uto32F, types.TUINT32},
  2754  	{types.TUINT32, types.TFLOAT64}: {ssaop.OpCopy, ssaop.OpCvt32Uto64F, types.TUINT32},
  2755  	{types.TFLOAT32, types.TUINT32}: {ssaop.OpCvt32Fto32U, ssaop.OpCopy, types.TUINT32},
  2756  	{types.TFLOAT64, types.TUINT32}: {ssaop.OpCvt64Fto32U, ssaop.OpCopy, types.TUINT32},
  2757  }
  2758  
  2759  // uint64<->float conversions, only on machines that have instructions for that
  2760  var uint64fpConvOpToSSA = map[twoTypes]twoOpsAndType{
  2761  	{types.TUINT64, types.TFLOAT32}: {ssaop.OpCopy, ssaop.OpCvt64Uto32F, types.TUINT64},
  2762  	{types.TUINT64, types.TFLOAT64}: {ssaop.OpCopy, ssaop.OpCvt64Uto64F, types.TUINT64},
  2763  	{types.TFLOAT32, types.TUINT64}: {ssaop.OpCvt32Fto64U, ssaop.OpCopy, types.TUINT64},
  2764  	{types.TFLOAT64, types.TUINT64}: {ssaop.OpCvt64Fto64U, ssaop.OpCopy, types.TUINT64},
  2765  }
  2766  
  2767  var shiftOpToSSA = map[opAndTwoTypes]ssaop.Op{
  2768  	{ir.OLSH, types.TINT8, types.TUINT8}:   ssaop.OpLsh8x8,
  2769  	{ir.OLSH, types.TUINT8, types.TUINT8}:  ssaop.OpLsh8x8,
  2770  	{ir.OLSH, types.TINT8, types.TUINT16}:  ssaop.OpLsh8x16,
  2771  	{ir.OLSH, types.TUINT8, types.TUINT16}: ssaop.OpLsh8x16,
  2772  	{ir.OLSH, types.TINT8, types.TUINT32}:  ssaop.OpLsh8x32,
  2773  	{ir.OLSH, types.TUINT8, types.TUINT32}: ssaop.OpLsh8x32,
  2774  	{ir.OLSH, types.TINT8, types.TUINT64}:  ssaop.OpLsh8x64,
  2775  	{ir.OLSH, types.TUINT8, types.TUINT64}: ssaop.OpLsh8x64,
  2776  
  2777  	{ir.OLSH, types.TINT16, types.TUINT8}:   ssaop.OpLsh16x8,
  2778  	{ir.OLSH, types.TUINT16, types.TUINT8}:  ssaop.OpLsh16x8,
  2779  	{ir.OLSH, types.TINT16, types.TUINT16}:  ssaop.OpLsh16x16,
  2780  	{ir.OLSH, types.TUINT16, types.TUINT16}: ssaop.OpLsh16x16,
  2781  	{ir.OLSH, types.TINT16, types.TUINT32}:  ssaop.OpLsh16x32,
  2782  	{ir.OLSH, types.TUINT16, types.TUINT32}: ssaop.OpLsh16x32,
  2783  	{ir.OLSH, types.TINT16, types.TUINT64}:  ssaop.OpLsh16x64,
  2784  	{ir.OLSH, types.TUINT16, types.TUINT64}: ssaop.OpLsh16x64,
  2785  
  2786  	{ir.OLSH, types.TINT32, types.TUINT8}:   ssaop.OpLsh32x8,
  2787  	{ir.OLSH, types.TUINT32, types.TUINT8}:  ssaop.OpLsh32x8,
  2788  	{ir.OLSH, types.TINT32, types.TUINT16}:  ssaop.OpLsh32x16,
  2789  	{ir.OLSH, types.TUINT32, types.TUINT16}: ssaop.OpLsh32x16,
  2790  	{ir.OLSH, types.TINT32, types.TUINT32}:  ssaop.OpLsh32x32,
  2791  	{ir.OLSH, types.TUINT32, types.TUINT32}: ssaop.OpLsh32x32,
  2792  	{ir.OLSH, types.TINT32, types.TUINT64}:  ssaop.OpLsh32x64,
  2793  	{ir.OLSH, types.TUINT32, types.TUINT64}: ssaop.OpLsh32x64,
  2794  
  2795  	{ir.OLSH, types.TINT64, types.TUINT8}:   ssaop.OpLsh64x8,
  2796  	{ir.OLSH, types.TUINT64, types.TUINT8}:  ssaop.OpLsh64x8,
  2797  	{ir.OLSH, types.TINT64, types.TUINT16}:  ssaop.OpLsh64x16,
  2798  	{ir.OLSH, types.TUINT64, types.TUINT16}: ssaop.OpLsh64x16,
  2799  	{ir.OLSH, types.TINT64, types.TUINT32}:  ssaop.OpLsh64x32,
  2800  	{ir.OLSH, types.TUINT64, types.TUINT32}: ssaop.OpLsh64x32,
  2801  	{ir.OLSH, types.TINT64, types.TUINT64}:  ssaop.OpLsh64x64,
  2802  	{ir.OLSH, types.TUINT64, types.TUINT64}: ssaop.OpLsh64x64,
  2803  
  2804  	{ir.ORSH, types.TINT8, types.TUINT8}:   ssaop.OpRsh8x8,
  2805  	{ir.ORSH, types.TUINT8, types.TUINT8}:  ssaop.OpRsh8Ux8,
  2806  	{ir.ORSH, types.TINT8, types.TUINT16}:  ssaop.OpRsh8x16,
  2807  	{ir.ORSH, types.TUINT8, types.TUINT16}: ssaop.OpRsh8Ux16,
  2808  	{ir.ORSH, types.TINT8, types.TUINT32}:  ssaop.OpRsh8x32,
  2809  	{ir.ORSH, types.TUINT8, types.TUINT32}: ssaop.OpRsh8Ux32,
  2810  	{ir.ORSH, types.TINT8, types.TUINT64}:  ssaop.OpRsh8x64,
  2811  	{ir.ORSH, types.TUINT8, types.TUINT64}: ssaop.OpRsh8Ux64,
  2812  
  2813  	{ir.ORSH, types.TINT16, types.TUINT8}:   ssaop.OpRsh16x8,
  2814  	{ir.ORSH, types.TUINT16, types.TUINT8}:  ssaop.OpRsh16Ux8,
  2815  	{ir.ORSH, types.TINT16, types.TUINT16}:  ssaop.OpRsh16x16,
  2816  	{ir.ORSH, types.TUINT16, types.TUINT16}: ssaop.OpRsh16Ux16,
  2817  	{ir.ORSH, types.TINT16, types.TUINT32}:  ssaop.OpRsh16x32,
  2818  	{ir.ORSH, types.TUINT16, types.TUINT32}: ssaop.OpRsh16Ux32,
  2819  	{ir.ORSH, types.TINT16, types.TUINT64}:  ssaop.OpRsh16x64,
  2820  	{ir.ORSH, types.TUINT16, types.TUINT64}: ssaop.OpRsh16Ux64,
  2821  
  2822  	{ir.ORSH, types.TINT32, types.TUINT8}:   ssaop.OpRsh32x8,
  2823  	{ir.ORSH, types.TUINT32, types.TUINT8}:  ssaop.OpRsh32Ux8,
  2824  	{ir.ORSH, types.TINT32, types.TUINT16}:  ssaop.OpRsh32x16,
  2825  	{ir.ORSH, types.TUINT32, types.TUINT16}: ssaop.OpRsh32Ux16,
  2826  	{ir.ORSH, types.TINT32, types.TUINT32}:  ssaop.OpRsh32x32,
  2827  	{ir.ORSH, types.TUINT32, types.TUINT32}: ssaop.OpRsh32Ux32,
  2828  	{ir.ORSH, types.TINT32, types.TUINT64}:  ssaop.OpRsh32x64,
  2829  	{ir.ORSH, types.TUINT32, types.TUINT64}: ssaop.OpRsh32Ux64,
  2830  
  2831  	{ir.ORSH, types.TINT64, types.TUINT8}:   ssaop.OpRsh64x8,
  2832  	{ir.ORSH, types.TUINT64, types.TUINT8}:  ssaop.OpRsh64Ux8,
  2833  	{ir.ORSH, types.TINT64, types.TUINT16}:  ssaop.OpRsh64x16,
  2834  	{ir.ORSH, types.TUINT64, types.TUINT16}: ssaop.OpRsh64Ux16,
  2835  	{ir.ORSH, types.TINT64, types.TUINT32}:  ssaop.OpRsh64x32,
  2836  	{ir.ORSH, types.TUINT64, types.TUINT32}: ssaop.OpRsh64Ux32,
  2837  	{ir.ORSH, types.TINT64, types.TUINT64}:  ssaop.OpRsh64x64,
  2838  	{ir.ORSH, types.TUINT64, types.TUINT64}: ssaop.OpRsh64Ux64,
  2839  }
  2840  
  2841  func (s *state) ssaShiftOp(op ir.Op, t *types.Type, u *types.Type) ssaop.Op {
  2842  	etype1 := s.concreteEtype(t)
  2843  	etype2 := s.concreteEtype(u)
  2844  	x, ok := shiftOpToSSA[opAndTwoTypes{op, etype1, etype2}]
  2845  	if !ok {
  2846  		s.Fatalf("unhandled shift op %v etype=%s/%s", op, etype1, etype2)
  2847  	}
  2848  	return x
  2849  }
  2850  
  2851  func (s *state) uintptrConstant(v uint64) *ssa.Value {
  2852  	if s.config.PtrSize == 4 {
  2853  		return s.newValue0I(ssaop.OpConst32, types.Types[types.TUINTPTR], int64(v))
  2854  	}
  2855  	return s.newValue0I(ssaop.OpConst64, types.Types[types.TUINTPTR], int64(v))
  2856  }
  2857  
  2858  func (s *state) conv(n ir.Node, v *ssa.Value, ft, tt *types.Type) *ssa.Value {
  2859  	if ft.IsBoolean() && tt.IsKind(types.TUINT8) {
  2860  		// Bool -> uint8 is generated internally when indexing into runtime.staticbyte.
  2861  		return s.newValue1(ssaop.OpCvtBoolToUint8, tt, v)
  2862  	}
  2863  	if ft.IsInteger() && tt.IsInteger() {
  2864  		var op ssaop.Op
  2865  		if tt.Size() == ft.Size() {
  2866  			op = ssaop.OpCopy
  2867  		} else if tt.Size() < ft.Size() {
  2868  			// truncation
  2869  			switch 10*ft.Size() + tt.Size() {
  2870  			case 21:
  2871  				op = ssaop.OpTrunc16to8
  2872  			case 41:
  2873  				op = ssaop.OpTrunc32to8
  2874  			case 42:
  2875  				op = ssaop.OpTrunc32to16
  2876  			case 81:
  2877  				op = ssaop.OpTrunc64to8
  2878  			case 82:
  2879  				op = ssaop.OpTrunc64to16
  2880  			case 84:
  2881  				op = ssaop.OpTrunc64to32
  2882  			default:
  2883  				s.Fatalf("weird integer truncation %v -> %v", ft, tt)
  2884  			}
  2885  		} else if ft.IsSigned() {
  2886  			// sign extension
  2887  			switch 10*ft.Size() + tt.Size() {
  2888  			case 12:
  2889  				op = ssaop.OpSignExt8to16
  2890  			case 14:
  2891  				op = ssaop.OpSignExt8to32
  2892  			case 18:
  2893  				op = ssaop.OpSignExt8to64
  2894  			case 24:
  2895  				op = ssaop.OpSignExt16to32
  2896  			case 28:
  2897  				op = ssaop.OpSignExt16to64
  2898  			case 48:
  2899  				op = ssaop.OpSignExt32to64
  2900  			default:
  2901  				s.Fatalf("bad integer sign extension %v -> %v", ft, tt)
  2902  			}
  2903  		} else {
  2904  			// zero extension
  2905  			switch 10*ft.Size() + tt.Size() {
  2906  			case 12:
  2907  				op = ssaop.OpZeroExt8to16
  2908  			case 14:
  2909  				op = ssaop.OpZeroExt8to32
  2910  			case 18:
  2911  				op = ssaop.OpZeroExt8to64
  2912  			case 24:
  2913  				op = ssaop.OpZeroExt16to32
  2914  			case 28:
  2915  				op = ssaop.OpZeroExt16to64
  2916  			case 48:
  2917  				op = ssaop.OpZeroExt32to64
  2918  			default:
  2919  				s.Fatalf("weird integer sign extension %v -> %v", ft, tt)
  2920  			}
  2921  		}
  2922  		return s.newValue1(op, tt, v)
  2923  	}
  2924  
  2925  	if ft.IsComplex() && tt.IsComplex() {
  2926  		var op ssaop.Op
  2927  		if ft.Size() == tt.Size() {
  2928  			switch ft.Size() {
  2929  			case 8:
  2930  				op = ssaop.OpRound32F
  2931  			case 16:
  2932  				op = ssaop.OpRound64F
  2933  			default:
  2934  				s.Fatalf("weird complex conversion %v -> %v", ft, tt)
  2935  			}
  2936  		} else if ft.Size() == 8 && tt.Size() == 16 {
  2937  			op = ssaop.OpCvt32Fto64F
  2938  		} else if ft.Size() == 16 && tt.Size() == 8 {
  2939  			op = ssaop.OpCvt64Fto32F
  2940  		} else {
  2941  			s.Fatalf("weird complex conversion %v -> %v", ft, tt)
  2942  		}
  2943  		ftp := types.FloatForComplex(ft)
  2944  		ttp := types.FloatForComplex(tt)
  2945  		return s.newValue2(ssaop.OpComplexMake, tt,
  2946  			s.newValueOrSfCall1(op, ttp, s.newValue1(ssaop.OpComplexReal, ftp, v)),
  2947  			s.newValueOrSfCall1(op, ttp, s.newValue1(ssaop.OpComplexImag, ftp, v)))
  2948  	}
  2949  
  2950  	if tt.IsComplex() { // and ft is not complex
  2951  		// Needed for generics support - can't happen in normal Go code.
  2952  		et := types.FloatForComplex(tt)
  2953  		v = s.conv(n, v, ft, et)
  2954  		return s.newValue2(ssaop.OpComplexMake, tt, v, s.zeroVal(et))
  2955  	}
  2956  
  2957  	if ft.IsFloat() || tt.IsFloat() {
  2958  		cft, ctt := s.concreteEtype(ft), s.concreteEtype(tt)
  2959  		conv, ok := fpConvOpToSSA[twoTypes{cft, ctt}]
  2960  		// there's a change to a conversion-op table, this restores the old behavior if ConvertHash is false.
  2961  		// use salted hash to distinguish unsigned convert at a Pos from signed convert at a Pos
  2962  		if ctt == types.TUINT32 && ft.IsFloat() && !base.ConvertHash.MatchPosWithInfo(n.Pos(), "U", nil) {
  2963  			// revert to old behavior
  2964  			conv.op1 = ssaop.OpCvt64Fto64
  2965  			if cft == types.TFLOAT32 {
  2966  				conv.op1 = ssaop.OpCvt32Fto64
  2967  			}
  2968  			conv.op2 = ssaop.OpTrunc64to32
  2969  
  2970  		}
  2971  		if s.config.RegSize == 4 && Arch.LinkArch.Family != sys.MIPS && !s.softFloat {
  2972  			if conv1, ok1 := fpConvOpToSSA32[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
  2973  				conv = conv1
  2974  			}
  2975  		}
  2976  		if Arch.LinkArch.Family == sys.ARM64 || Arch.LinkArch.Family == sys.Wasm || Arch.LinkArch.Family == sys.S390X || s.softFloat {
  2977  			if conv1, ok1 := uint64fpConvOpToSSA[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
  2978  				conv = conv1
  2979  			}
  2980  		}
  2981  
  2982  		if Arch.LinkArch.Family == sys.MIPS && !s.softFloat {
  2983  			if ft.Size() == 4 && ft.IsInteger() && !ft.IsSigned() {
  2984  				// tt is float32 or float64, and ft is also unsigned
  2985  				if tt.Size() == 4 {
  2986  					return s.uint32Tofloat32(n, v, ft, tt)
  2987  				}
  2988  				if tt.Size() == 8 {
  2989  					return s.uint32Tofloat64(n, v, ft, tt)
  2990  				}
  2991  			} else if tt.Size() == 4 && tt.IsInteger() && !tt.IsSigned() {
  2992  				// ft is float32 or float64, and tt is unsigned integer
  2993  				if ft.Size() == 4 {
  2994  					return s.float32ToUint32(n, v, ft, tt)
  2995  				}
  2996  				if ft.Size() == 8 {
  2997  					return s.float64ToUint32(n, v, ft, tt)
  2998  				}
  2999  			}
  3000  		}
  3001  
  3002  		if !ok {
  3003  			s.Fatalf("weird float conversion %v -> %v", ft, tt)
  3004  		}
  3005  		op1, op2, it := conv.op1, conv.op2, conv.intermediateType
  3006  
  3007  		if op1 != ssaop.OpInvalid && op2 != ssaop.OpInvalid {
  3008  			// normal case, not tripping over unsigned 64
  3009  			if op1 == ssaop.OpCopy {
  3010  				if op2 == ssaop.OpCopy {
  3011  					return v
  3012  				}
  3013  				return s.newValueOrSfCall1(op2, tt, v)
  3014  			}
  3015  			if op2 == ssaop.OpCopy {
  3016  				return s.newValueOrSfCall1(op1, tt, v)
  3017  			}
  3018  			return s.newValueOrSfCall1(op2, tt, s.newValueOrSfCall1(op1, types.Types[it], v))
  3019  		}
  3020  		// Tricky 64-bit unsigned cases.
  3021  		if ft.IsInteger() {
  3022  			// tt is float32 or float64, and ft is also unsigned
  3023  			if tt.Size() == 4 {
  3024  				return s.uint64Tofloat32(n, v, ft, tt)
  3025  			}
  3026  			if tt.Size() == 8 {
  3027  				return s.uint64Tofloat64(n, v, ft, tt)
  3028  			}
  3029  			s.Fatalf("weird unsigned integer to float conversion %v -> %v", ft, tt)
  3030  		}
  3031  		// ft is float32 or float64, and tt is unsigned integer
  3032  		if ft.Size() == 4 {
  3033  			switch tt.Size() {
  3034  			case 8:
  3035  				return s.float32ToUint64(n, v, ft, tt)
  3036  			case 4, 2, 1:
  3037  				// TODO should 2 and 1 saturate or truncate?
  3038  				return s.float32ToUint32(n, v, ft, tt)
  3039  			}
  3040  		}
  3041  		if ft.Size() == 8 {
  3042  			switch tt.Size() {
  3043  			case 8:
  3044  				return s.float64ToUint64(n, v, ft, tt)
  3045  			case 4, 2, 1:
  3046  				// TODO should 2 and 1 saturate or truncate?
  3047  				return s.float64ToUint32(n, v, ft, tt)
  3048  			}
  3049  
  3050  		}
  3051  		s.Fatalf("weird float to unsigned integer conversion %v -> %v", ft, tt)
  3052  		return nil
  3053  	}
  3054  
  3055  	s.Fatalf("unhandled OCONV %s -> %s", ft.Kind(), tt.Kind())
  3056  	return nil
  3057  }
  3058  
  3059  // expr converts the expression n to ssa, adds it to s and returns the ssa result.
  3060  func (s *state) expr(n ir.Node) *ssa.Value {
  3061  	return s.exprCheckPtr(n, true)
  3062  }
  3063  
  3064  func (s *state) exprCheckPtr(n ir.Node, checkPtrOK bool) *ssa.Value {
  3065  	if ir.HasUniquePos(n) {
  3066  		// ONAMEs and named OLITERALs have the line number
  3067  		// of the decl, not the use. See issue 14742.
  3068  		s.pushLine(n.Pos())
  3069  		defer s.popLine()
  3070  	}
  3071  
  3072  	s.stmtList(n.Init())
  3073  	switch n.Op() {
  3074  	case ir.OBYTES2STRTMP:
  3075  		n := n.(*ir.ConvExpr)
  3076  		slice := s.expr(n.X)
  3077  		ptr := s.newValue1(ssaop.OpSlicePtr, s.f.Config.Types.BytePtr, slice)
  3078  		len := s.newValue1(ssaop.OpSliceLen, types.Types[types.TINT], slice)
  3079  		return s.newValue2(ssaop.OpStringMake, n.Type(), ptr, len)
  3080  	case ir.OSTR2BYTESTMP:
  3081  		n := n.(*ir.ConvExpr)
  3082  		str := s.expr(n.X)
  3083  		ptr := s.newValue1(ssaop.OpStringPtr, s.f.Config.Types.BytePtr, str)
  3084  		if !n.NonNil() {
  3085  			// We need to ensure []byte("") evaluates to []byte{}, and not []byte(nil).
  3086  			//
  3087  			// TODO(mdempsky): Investigate using "len != 0" instead of "ptr != nil".
  3088  			cond := s.newValue2(ssaop.OpNeqPtr, types.Types[types.TBOOL], ptr, s.constNil(ptr.Type))
  3089  			zerobase := s.newValue1A(ssaop.OpAddr, ptr.Type, ir.Syms.Zerobase, s.sb)
  3090  			ptr = s.ternary(cond, ptr, zerobase)
  3091  		}
  3092  		len := s.newValue1(ssaop.OpStringLen, types.Types[types.TINT], str)
  3093  		return s.newValue3(ssaop.OpSliceMake, n.Type(), ptr, len, len)
  3094  	case ir.OCFUNC:
  3095  		n := n.(*ir.UnaryExpr)
  3096  		aux := n.X.(*ir.Name).Linksym()
  3097  		// OCFUNC is used to build function values, which must
  3098  		// always reference ABIInternal entry points.
  3099  		if aux.ABI() != obj.ABIInternal {
  3100  			s.Fatalf("expected ABIInternal: %v", aux.ABI())
  3101  		}
  3102  		return s.entryNewValue1A(ssaop.OpAddr, n.Type(), aux, s.sb)
  3103  	case ir.ONAME:
  3104  		n := n.(*ir.Name)
  3105  		if n.Class == ir.PFUNC {
  3106  			// "value" of a function is the address of the function's closure
  3107  			sym := staticdata.FuncLinksym(n)
  3108  			return s.entryNewValue1A(ssaop.OpAddr, types.NewPtr(n.Type()), sym, s.sb)
  3109  		}
  3110  		if s.canSSA(n) {
  3111  			return s.variable(n, n.Type())
  3112  		}
  3113  		return s.load(n.Type(), s.addr(n))
  3114  	case ir.OLINKSYMOFFSET:
  3115  		n := n.(*ir.LinksymOffsetExpr)
  3116  		return s.load(n.Type(), s.addr(n))
  3117  	case ir.ONIL:
  3118  		n := n.(*ir.NilExpr)
  3119  		t := n.Type()
  3120  		switch {
  3121  		case t.IsSlice():
  3122  			return s.constSlice(t)
  3123  		case t.IsInterface():
  3124  			return s.constInterface(t)
  3125  		default:
  3126  			return s.constNil(t)
  3127  		}
  3128  	case ir.OLITERAL:
  3129  		switch u := n.Val(); u.Kind() {
  3130  		case constant.Int:
  3131  			i := ir.IntVal(n.Type(), u)
  3132  			switch n.Type().Size() {
  3133  			case 1:
  3134  				return s.constInt8(n.Type(), int8(i))
  3135  			case 2:
  3136  				return s.constInt16(n.Type(), int16(i))
  3137  			case 4:
  3138  				return s.constInt32(n.Type(), int32(i))
  3139  			case 8:
  3140  				return s.constInt64(n.Type(), i)
  3141  			default:
  3142  				s.Fatalf("bad integer size %d", n.Type().Size())
  3143  				return nil
  3144  			}
  3145  		case constant.String:
  3146  			i := constant.StringVal(u)
  3147  			if i == "" {
  3148  				return s.constEmptyString(n.Type())
  3149  			}
  3150  			return s.entryNewValue0A(ssaop.OpConstString, n.Type(), ssa.StringToAux(i))
  3151  		case constant.Bool:
  3152  			return s.constBool(constant.BoolVal(u))
  3153  		case constant.Float:
  3154  			f, _ := constant.Float64Val(u)
  3155  			switch n.Type().Size() {
  3156  			case 4:
  3157  				return s.constFloat32(n.Type(), f)
  3158  			case 8:
  3159  				return s.constFloat64(n.Type(), f)
  3160  			default:
  3161  				s.Fatalf("bad float size %d", n.Type().Size())
  3162  				return nil
  3163  			}
  3164  		case constant.Complex:
  3165  			re, _ := constant.Float64Val(constant.Real(u))
  3166  			im, _ := constant.Float64Val(constant.Imag(u))
  3167  			switch n.Type().Size() {
  3168  			case 8:
  3169  				pt := types.Types[types.TFLOAT32]
  3170  				return s.newValue2(ssaop.OpComplexMake, n.Type(),
  3171  					s.constFloat32(pt, re),
  3172  					s.constFloat32(pt, im))
  3173  			case 16:
  3174  				pt := types.Types[types.TFLOAT64]
  3175  				return s.newValue2(ssaop.OpComplexMake, n.Type(),
  3176  					s.constFloat64(pt, re),
  3177  					s.constFloat64(pt, im))
  3178  			default:
  3179  				s.Fatalf("bad complex size %d", n.Type().Size())
  3180  				return nil
  3181  			}
  3182  		default:
  3183  			s.Fatalf("unhandled OLITERAL %v", u.Kind())
  3184  			return nil
  3185  		}
  3186  	case ir.OCONVNOP:
  3187  		n := n.(*ir.ConvExpr)
  3188  		to := n.Type()
  3189  		from := n.X.Type()
  3190  
  3191  		// Assume everything will work out, so set up our return value.
  3192  		// Anything interesting that happens from here is a fatal.
  3193  		x := s.expr(n.X)
  3194  		if to == from {
  3195  			return x
  3196  		}
  3197  
  3198  		// Special case for not confusing GC and liveness.
  3199  		// We don't want pointers accidentally classified
  3200  		// as not-pointers or vice-versa because of copy
  3201  		// elision.
  3202  		if to.IsPtrShaped() != from.IsPtrShaped() {
  3203  			return s.newValue2(ssaop.OpConvert, to, x, s.mem())
  3204  		}
  3205  
  3206  		v := s.newValue1(ssaop.OpCopy, to, x) // ensure that v has the right type
  3207  
  3208  		// CONVNOP closure
  3209  		if to.Kind() == types.TFUNC && from.IsPtrShaped() {
  3210  			return v
  3211  		}
  3212  
  3213  		// named <--> unnamed type or typed <--> untyped const
  3214  		if from.Kind() == to.Kind() {
  3215  			return v
  3216  		}
  3217  
  3218  		// unsafe.Pointer <--> *T
  3219  		if to.IsUnsafePtr() && from.IsPtrShaped() || from.IsUnsafePtr() && to.IsPtrShaped() {
  3220  			if s.checkPtrEnabled && checkPtrOK && to.IsPtr() && from.IsUnsafePtr() {
  3221  				s.checkPtrAlignment(n, v, nil)
  3222  			}
  3223  			return v
  3224  		}
  3225  
  3226  		// map <--> *internal/runtime/maps.Map
  3227  		mt := types.NewPtr(reflectdata.MapType())
  3228  		if to.Kind() == types.TMAP && from == mt {
  3229  			return v
  3230  		}
  3231  
  3232  		types.CalcSize(from)
  3233  		types.CalcSize(to)
  3234  		if from.Size() != to.Size() {
  3235  			s.Fatalf("CONVNOP width mismatch %v (%d) -> %v (%d)\n", from, from.Size(), to, to.Size())
  3236  			return nil
  3237  		}
  3238  		if etypesign(from.Kind()) != etypesign(to.Kind()) {
  3239  			s.Fatalf("CONVNOP sign mismatch %v (%s) -> %v (%s)\n", from, from.Kind(), to, to.Kind())
  3240  			return nil
  3241  		}
  3242  
  3243  		if base.Flag.Cfg.Instrumenting {
  3244  			// These appear to be fine, but they fail the
  3245  			// integer constraint below, so okay them here.
  3246  			// Sample non-integer conversion: map[string]string -> *uint8
  3247  			return v
  3248  		}
  3249  
  3250  		if etypesign(from.Kind()) == 0 {
  3251  			s.Fatalf("CONVNOP unrecognized non-integer %v -> %v\n", from, to)
  3252  			return nil
  3253  		}
  3254  
  3255  		// integer, same width, same sign
  3256  		return v
  3257  
  3258  	case ir.OCONV:
  3259  		n := n.(*ir.ConvExpr)
  3260  		x := s.expr(n.X)
  3261  		return s.conv(n, x, n.X.Type(), n.Type())
  3262  
  3263  	case ir.ODOTTYPE:
  3264  		n := n.(*ir.TypeAssertExpr)
  3265  		res, _ := s.dottype(n, false)
  3266  		return res
  3267  
  3268  	case ir.ODYNAMICDOTTYPE:
  3269  		n := n.(*ir.DynamicTypeAssertExpr)
  3270  		res, _ := s.dynamicDottype(n, false)
  3271  		return res
  3272  
  3273  	// binary ops
  3274  	case ir.OLT, ir.OEQ, ir.ONE, ir.OLE, ir.OGE, ir.OGT:
  3275  		n := n.(*ir.BinaryExpr)
  3276  		a := s.expr(n.X)
  3277  		b := s.expr(n.Y)
  3278  		if n.X.Type().IsComplex() {
  3279  			pt := types.FloatForComplex(n.X.Type())
  3280  			op := s.ssaOp(ir.OEQ, pt)
  3281  			r := s.newValueOrSfCall2(op, types.Types[types.TBOOL], s.newValue1(ssaop.OpComplexReal, pt, a), s.newValue1(ssaop.OpComplexReal, pt, b))
  3282  			i := s.newValueOrSfCall2(op, types.Types[types.TBOOL], s.newValue1(ssaop.OpComplexImag, pt, a), s.newValue1(ssaop.OpComplexImag, pt, b))
  3283  			c := s.newValue2(ssaop.OpAndB, types.Types[types.TBOOL], r, i)
  3284  			switch n.Op() {
  3285  			case ir.OEQ:
  3286  				return c
  3287  			case ir.ONE:
  3288  				return s.newValue1(ssaop.OpNot, types.Types[types.TBOOL], c)
  3289  			default:
  3290  				s.Fatalf("ordered complex compare %v", n.Op())
  3291  			}
  3292  		}
  3293  
  3294  		// Convert OGE and OGT into OLE and OLT.
  3295  		op := n.Op()
  3296  		switch op {
  3297  		case ir.OGE:
  3298  			op, a, b = ir.OLE, b, a
  3299  		case ir.OGT:
  3300  			op, a, b = ir.OLT, b, a
  3301  		}
  3302  		if n.X.Type().IsFloat() {
  3303  			// float comparison
  3304  			return s.newValueOrSfCall2(s.ssaOp(op, n.X.Type()), types.Types[types.TBOOL], a, b)
  3305  		}
  3306  		// integer comparison
  3307  		return s.newValue2(s.ssaOp(op, n.X.Type()), types.Types[types.TBOOL], a, b)
  3308  	case ir.OMUL:
  3309  		n := n.(*ir.BinaryExpr)
  3310  		a := s.expr(n.X)
  3311  		b := s.expr(n.Y)
  3312  		if n.Type().IsComplex() {
  3313  			mulop := ssaop.OpMul64F
  3314  			addop := ssaop.OpAdd64F
  3315  			subop := ssaop.OpSub64F
  3316  			pt := types.FloatForComplex(n.Type()) // Could be Float32 or Float64
  3317  			wt := types.Types[types.TFLOAT64]     // Compute in Float64 to minimize cancellation error
  3318  
  3319  			areal := s.newValue1(ssaop.OpComplexReal, pt, a)
  3320  			breal := s.newValue1(ssaop.OpComplexReal, pt, b)
  3321  			aimag := s.newValue1(ssaop.OpComplexImag, pt, a)
  3322  			bimag := s.newValue1(ssaop.OpComplexImag, pt, b)
  3323  
  3324  			if pt != wt { // Widen for calculation
  3325  				areal = s.newValueOrSfCall1(ssaop.OpCvt32Fto64F, wt, areal)
  3326  				breal = s.newValueOrSfCall1(ssaop.OpCvt32Fto64F, wt, breal)
  3327  				aimag = s.newValueOrSfCall1(ssaop.OpCvt32Fto64F, wt, aimag)
  3328  				bimag = s.newValueOrSfCall1(ssaop.OpCvt32Fto64F, wt, bimag)
  3329  			}
  3330  
  3331  			xreal := s.newValueOrSfCall2(subop, wt, s.newValueOrSfCall2(mulop, wt, areal, breal), s.newValueOrSfCall2(mulop, wt, aimag, bimag))
  3332  			ximag := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, areal, bimag), s.newValueOrSfCall2(mulop, wt, aimag, breal))
  3333  
  3334  			if pt != wt { // Narrow to store back
  3335  				xreal = s.newValueOrSfCall1(ssaop.OpCvt64Fto32F, pt, xreal)
  3336  				ximag = s.newValueOrSfCall1(ssaop.OpCvt64Fto32F, pt, ximag)
  3337  			}
  3338  
  3339  			return s.newValue2(ssaop.OpComplexMake, n.Type(), xreal, ximag)
  3340  		}
  3341  
  3342  		if n.Type().IsFloat() {
  3343  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3344  		}
  3345  
  3346  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3347  
  3348  	case ir.ODIV:
  3349  		n := n.(*ir.BinaryExpr)
  3350  		a := s.expr(n.X)
  3351  		b := s.expr(n.Y)
  3352  		if n.Type().IsComplex() {
  3353  			// TODO this is not executed because the front-end substitutes a runtime call.
  3354  			// That probably ought to change; with modest optimization the widen/narrow
  3355  			// conversions could all be elided in larger expression trees.
  3356  			mulop := ssaop.OpMul64F
  3357  			addop := ssaop.OpAdd64F
  3358  			subop := ssaop.OpSub64F
  3359  			divop := ssaop.OpDiv64F
  3360  			pt := types.FloatForComplex(n.Type()) // Could be Float32 or Float64
  3361  			wt := types.Types[types.TFLOAT64]     // Compute in Float64 to minimize cancellation error
  3362  
  3363  			areal := s.newValue1(ssaop.OpComplexReal, pt, a)
  3364  			breal := s.newValue1(ssaop.OpComplexReal, pt, b)
  3365  			aimag := s.newValue1(ssaop.OpComplexImag, pt, a)
  3366  			bimag := s.newValue1(ssaop.OpComplexImag, pt, b)
  3367  
  3368  			if pt != wt { // Widen for calculation
  3369  				areal = s.newValueOrSfCall1(ssaop.OpCvt32Fto64F, wt, areal)
  3370  				breal = s.newValueOrSfCall1(ssaop.OpCvt32Fto64F, wt, breal)
  3371  				aimag = s.newValueOrSfCall1(ssaop.OpCvt32Fto64F, wt, aimag)
  3372  				bimag = s.newValueOrSfCall1(ssaop.OpCvt32Fto64F, wt, bimag)
  3373  			}
  3374  
  3375  			denom := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, breal, breal), s.newValueOrSfCall2(mulop, wt, bimag, bimag))
  3376  			xreal := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, areal, breal), s.newValueOrSfCall2(mulop, wt, aimag, bimag))
  3377  			ximag := s.newValueOrSfCall2(subop, wt, s.newValueOrSfCall2(mulop, wt, aimag, breal), s.newValueOrSfCall2(mulop, wt, areal, bimag))
  3378  
  3379  			// TODO not sure if this is best done in wide precision or narrow
  3380  			// Double-rounding might be an issue.
  3381  			// Note that the pre-SSA implementation does the entire calculation
  3382  			// in wide format, so wide is compatible.
  3383  			xreal = s.newValueOrSfCall2(divop, wt, xreal, denom)
  3384  			ximag = s.newValueOrSfCall2(divop, wt, ximag, denom)
  3385  
  3386  			if pt != wt { // Narrow to store back
  3387  				xreal = s.newValueOrSfCall1(ssaop.OpCvt64Fto32F, pt, xreal)
  3388  				ximag = s.newValueOrSfCall1(ssaop.OpCvt64Fto32F, pt, ximag)
  3389  			}
  3390  			return s.newValue2(ssaop.OpComplexMake, n.Type(), xreal, ximag)
  3391  		}
  3392  		if n.Type().IsFloat() {
  3393  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3394  		}
  3395  		return s.intDivide(n, a, b)
  3396  	case ir.OMOD:
  3397  		n := n.(*ir.BinaryExpr)
  3398  		a := s.expr(n.X)
  3399  		b := s.expr(n.Y)
  3400  		return s.intDivide(n, a, b)
  3401  	case ir.OADD, ir.OSUB:
  3402  		n := n.(*ir.BinaryExpr)
  3403  		a := s.expr(n.X)
  3404  		b := s.expr(n.Y)
  3405  		if n.Type().IsComplex() {
  3406  			pt := types.FloatForComplex(n.Type())
  3407  			op := s.ssaOp(n.Op(), pt)
  3408  			return s.newValue2(ssaop.OpComplexMake, n.Type(),
  3409  				s.newValueOrSfCall2(op, pt, s.newValue1(ssaop.OpComplexReal, pt, a), s.newValue1(ssaop.OpComplexReal, pt, b)),
  3410  				s.newValueOrSfCall2(op, pt, s.newValue1(ssaop.OpComplexImag, pt, a), s.newValue1(ssaop.OpComplexImag, pt, b)))
  3411  		}
  3412  		if n.Type().IsFloat() {
  3413  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3414  		}
  3415  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3416  	case ir.OAND, ir.OOR, ir.OXOR:
  3417  		n := n.(*ir.BinaryExpr)
  3418  		a := s.expr(n.X)
  3419  		b := s.expr(n.Y)
  3420  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3421  	case ir.OANDNOT:
  3422  		n := n.(*ir.BinaryExpr)
  3423  		a := s.expr(n.X)
  3424  		b := s.expr(n.Y)
  3425  		b = s.newValue1(s.ssaOp(ir.OBITNOT, b.Type), b.Type, b)
  3426  		return s.newValue2(s.ssaOp(ir.OAND, n.Type()), a.Type, a, b)
  3427  	case ir.OLSH, ir.ORSH:
  3428  		n := n.(*ir.BinaryExpr)
  3429  		a := s.expr(n.X)
  3430  		b := s.expr(n.Y)
  3431  		bt := b.Type
  3432  		if bt.IsSigned() {
  3433  			cmp := s.newValue2(s.ssaOp(ir.OLE, bt), types.Types[types.TBOOL], s.zeroVal(bt), b)
  3434  			s.check(cmp, ir.Syms.Panicshift)
  3435  			bt = bt.ToUnsigned()
  3436  		}
  3437  		return s.newValue2(s.ssaShiftOp(n.Op(), n.Type(), bt), a.Type, a, b)
  3438  	case ir.OANDAND, ir.OOROR:
  3439  		// To implement OANDAND (and OOROR), we introduce a
  3440  		// new temporary variable to hold the result. The
  3441  		// variable is associated with the OANDAND node in the
  3442  		// s.vars table (normally variables are only
  3443  		// associated with ONAME nodes). We convert
  3444  		//     A && B
  3445  		// to
  3446  		//     var = A
  3447  		//     if var {
  3448  		//         var = B
  3449  		//     }
  3450  		// Using var in the subsequent block introduces the
  3451  		// necessary phi variable.
  3452  		n := n.(*ir.LogicalExpr)
  3453  		el := s.expr(n.X)
  3454  		s.vars[n] = el
  3455  
  3456  		b := s.endBlock()
  3457  		b.Kind = block.BlockIf
  3458  		b.SetControl(el)
  3459  		// In theory, we should set b.Likely here based on context.
  3460  		// However, gc only gives us likeliness hints
  3461  		// in a single place, for plain OIF statements,
  3462  		// and passing around context is finicky, so don't bother for now.
  3463  
  3464  		bRight := s.f.NewBlock(block.BlockPlain)
  3465  		bResult := s.f.NewBlock(block.BlockPlain)
  3466  		if n.Op() == ir.OANDAND {
  3467  			b.AddEdgeTo(bRight)
  3468  			b.AddEdgeTo(bResult)
  3469  		} else if n.Op() == ir.OOROR {
  3470  			b.AddEdgeTo(bResult)
  3471  			b.AddEdgeTo(bRight)
  3472  		}
  3473  
  3474  		s.startBlock(bRight)
  3475  		er := s.expr(n.Y)
  3476  		s.vars[n] = er
  3477  
  3478  		b = s.endBlock()
  3479  		b.AddEdgeTo(bResult)
  3480  
  3481  		s.startBlock(bResult)
  3482  		return s.variable(n, types.Types[types.TBOOL])
  3483  	case ir.OCOMPLEX:
  3484  		n := n.(*ir.BinaryExpr)
  3485  		r := s.expr(n.X)
  3486  		i := s.expr(n.Y)
  3487  		return s.newValue2(ssaop.OpComplexMake, n.Type(), r, i)
  3488  
  3489  	// unary ops
  3490  	case ir.ONEG:
  3491  		n := n.(*ir.UnaryExpr)
  3492  		a := s.expr(n.X)
  3493  		if n.Type().IsComplex() {
  3494  			tp := types.FloatForComplex(n.Type())
  3495  			negop := s.ssaOp(n.Op(), tp)
  3496  			return s.newValue2(ssaop.OpComplexMake, n.Type(),
  3497  				s.newValue1(negop, tp, s.newValue1(ssaop.OpComplexReal, tp, a)),
  3498  				s.newValue1(negop, tp, s.newValue1(ssaop.OpComplexImag, tp, a)))
  3499  		}
  3500  		return s.newValue1(s.ssaOp(n.Op(), n.Type()), a.Type, a)
  3501  	case ir.ONOT, ir.OBITNOT:
  3502  		n := n.(*ir.UnaryExpr)
  3503  		a := s.expr(n.X)
  3504  		return s.newValue1(s.ssaOp(n.Op(), n.Type()), a.Type, a)
  3505  	case ir.OIMAG, ir.OREAL:
  3506  		n := n.(*ir.UnaryExpr)
  3507  		a := s.expr(n.X)
  3508  		return s.newValue1(s.ssaOp(n.Op(), n.X.Type()), n.Type(), a)
  3509  	case ir.OPLUS:
  3510  		n := n.(*ir.UnaryExpr)
  3511  		return s.expr(n.X)
  3512  
  3513  	case ir.OADDR:
  3514  		n := n.(*ir.AddrExpr)
  3515  		return s.addr(n.X)
  3516  
  3517  	case ir.ORESULT:
  3518  		n := n.(*ir.ResultExpr)
  3519  		if s.prevCall == nil || s.prevCall.Op != ssaop.OpStaticLECall && s.prevCall.Op != ssaop.OpInterLECall && s.prevCall.Op != ssaop.OpClosureLECall {
  3520  			panic("Expected to see a previous call")
  3521  		}
  3522  		which := n.Index
  3523  		if which == -1 {
  3524  			panic(fmt.Errorf("ORESULT %v does not match call %s", n, s.prevCall))
  3525  		}
  3526  		return s.resultOfCall(s.prevCall, which, n.Type())
  3527  
  3528  	case ir.ODEREF:
  3529  		n := n.(*ir.StarExpr)
  3530  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  3531  		return s.load(n.Type(), p)
  3532  
  3533  	case ir.ODOT:
  3534  		n := n.(*ir.SelectorExpr)
  3535  		if n.X.Op() == ir.OSTRUCTLIT {
  3536  			// All literals with nonzero fields have already been
  3537  			// rewritten during walk. Any that remain are just T{}
  3538  			// or equivalents. Use the zero value.
  3539  			if !ir.IsZero(n.X) {
  3540  				s.Fatalf("literal with nonzero value in SSA: %v", n.X)
  3541  			}
  3542  			return s.zeroVal(n.Type())
  3543  		}
  3544  		// If n is addressable and can't be represented in
  3545  		// SSA, then load just the selected field. This
  3546  		// prevents false memory dependencies in race/msan/asan
  3547  		// instrumentation.
  3548  		if ir.IsAddressable(n) && !s.canSSA(n) {
  3549  			p := s.addr(n)
  3550  			return s.load(n.Type(), p)
  3551  		}
  3552  		v := s.expr(n.X)
  3553  		return s.newValue1I(ssaop.OpStructSelect, n.Type(), int64(fieldIdx(n)), v)
  3554  
  3555  	case ir.ODOTPTR:
  3556  		n := n.(*ir.SelectorExpr)
  3557  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  3558  		p = s.newValue1I(ssaop.OpOffPtr, types.NewPtr(n.Type()), n.Offset(), p)
  3559  		return s.load(n.Type(), p)
  3560  
  3561  	case ir.OINDEX:
  3562  		n := n.(*ir.IndexExpr)
  3563  		switch {
  3564  		case n.X.Type().IsString():
  3565  			if n.Bounded() && ir.IsConst(n.X, constant.String) && ir.IsConst(n.Index, constant.Int) {
  3566  				// Replace "abc"[1] with 'b'.
  3567  				// Delayed until now because "abc"[1] is not an ideal constant.
  3568  				// See test/fixedbugs/issue11370.go.
  3569  				return s.newValue0I(ssaop.OpConst8, types.Types[types.TUINT8], int64(int8(ir.StringVal(n.X)[ir.Int64Val(n.Index)])))
  3570  			}
  3571  			a := s.expr(n.X)
  3572  			i := s.expr(n.Index)
  3573  			len := s.newValue1(ssaop.OpStringLen, types.Types[types.TINT], a)
  3574  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  3575  			ptrtyp := s.f.Config.Types.BytePtr
  3576  			ptr := s.newValue1(ssaop.OpStringPtr, ptrtyp, a)
  3577  			if ir.IsConst(n.Index, constant.Int) {
  3578  				ptr = s.newValue1I(ssaop.OpOffPtr, ptrtyp, ir.Int64Val(n.Index), ptr)
  3579  			} else {
  3580  				ptr = s.newValue2(ssaop.OpAddPtr, ptrtyp, ptr, i)
  3581  			}
  3582  			return s.load(types.Types[types.TUINT8], ptr)
  3583  		case n.X.Type().IsSlice():
  3584  			p := s.addr(n)
  3585  			return s.load(n.X.Type().Elem(), p)
  3586  		case n.X.Type().IsArray():
  3587  			if ssa.CanSSA(n.X.Type()) {
  3588  				// SSA can handle arrays of length at most 1.
  3589  				bound := n.X.Type().NumElem()
  3590  				a := s.expr(n.X)
  3591  				i := s.expr(n.Index)
  3592  				len := s.constInt(types.Types[types.TINT], bound)
  3593  				if bound == 0 {
  3594  					// Bounds check will never succeed.
  3595  					s.boundsCheck(i, len, ssa.BoundsIndex, false)
  3596  					// The return value won't be live. In case bounds checks
  3597  					// are turned off, load from (*T)(nil) to cause a segfault.
  3598  					return s.load(n.Type(), s.constNil(n.Type().PtrTo()))
  3599  				}
  3600  				s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded()) // checks i == 0
  3601  				return s.newValue1I(ssaop.OpArraySelect, n.Type(), 0, a)
  3602  			}
  3603  			p := s.addr(n)
  3604  			return s.load(n.X.Type().Elem(), p)
  3605  		default:
  3606  			s.Fatalf("bad type for index %v", n.X.Type())
  3607  			return nil
  3608  		}
  3609  
  3610  	case ir.OLEN, ir.OCAP:
  3611  		n := n.(*ir.UnaryExpr)
  3612  		// Note: all constant cases are handled by the frontend. If len or cap
  3613  		// makes it here, we want the side effects of the argument. See issue 72844.
  3614  		a := s.expr(n.X)
  3615  		t := n.X.Type()
  3616  		switch {
  3617  		case t.IsSlice():
  3618  			op := ssaop.OpSliceLen
  3619  			if n.Op() == ir.OCAP {
  3620  				op = ssaop.OpSliceCap
  3621  			}
  3622  			return s.newValue1(op, types.Types[types.TINT], a)
  3623  		case t.IsString(): // string; not reachable for OCAP
  3624  			return s.newValue1(ssaop.OpStringLen, types.Types[types.TINT], a)
  3625  		case t.IsMap(), t.IsChan():
  3626  			return s.referenceTypeBuiltin(n, a)
  3627  		case t.IsArray():
  3628  			return s.constInt(types.Types[types.TINT], t.NumElem())
  3629  		case t.IsPtr() && t.Elem().IsArray():
  3630  			return s.constInt(types.Types[types.TINT], t.Elem().NumElem())
  3631  		default:
  3632  			s.Fatalf("bad type in len/cap: %v", t)
  3633  			return nil
  3634  		}
  3635  
  3636  	case ir.OSPTR:
  3637  		n := n.(*ir.UnaryExpr)
  3638  		a := s.expr(n.X)
  3639  		if n.X.Type().IsSlice() {
  3640  			if n.Bounded() {
  3641  				return s.newValue1(ssaop.OpSlicePtr, n.Type(), a)
  3642  			}
  3643  			return s.newValue1(ssaop.OpSlicePtrUnchecked, n.Type(), a)
  3644  		} else {
  3645  			return s.newValue1(ssaop.OpStringPtr, n.Type(), a)
  3646  		}
  3647  
  3648  	case ir.OITAB:
  3649  		n := n.(*ir.UnaryExpr)
  3650  		a := s.expr(n.X)
  3651  		return s.newValue1(ssaop.OpITab, n.Type(), a)
  3652  
  3653  	case ir.OIDATA:
  3654  		n := n.(*ir.UnaryExpr)
  3655  		a := s.expr(n.X)
  3656  		return s.newValue1(ssaop.OpIData, n.Type(), a)
  3657  
  3658  	case ir.OMAKEFACE:
  3659  		n := n.(*ir.BinaryExpr)
  3660  		tab := s.expr(n.X)
  3661  		data := s.expr(n.Y)
  3662  		return s.newValue2(ssaop.OpIMake, n.Type(), tab, data)
  3663  
  3664  	case ir.OSLICEHEADER:
  3665  		n := n.(*ir.SliceHeaderExpr)
  3666  		p := s.expr(n.Ptr)
  3667  		l := s.expr(n.Len)
  3668  		c := s.expr(n.Cap)
  3669  		return s.newValue3(ssaop.OpSliceMake, n.Type(), p, l, c)
  3670  
  3671  	case ir.OSTRINGHEADER:
  3672  		n := n.(*ir.StringHeaderExpr)
  3673  		p := s.expr(n.Ptr)
  3674  		l := s.expr(n.Len)
  3675  		return s.newValue2(ssaop.OpStringMake, n.Type(), p, l)
  3676  
  3677  	case ir.OSLICE, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR:
  3678  		n := n.(*ir.SliceExpr)
  3679  		check := s.checkPtrEnabled && n.Op() == ir.OSLICE3ARR && n.X.Op() == ir.OCONVNOP && n.X.(*ir.ConvExpr).X.Type().IsUnsafePtr()
  3680  		v := s.exprCheckPtr(n.X, !check)
  3681  		var i, j, k *ssa.Value
  3682  		if n.Low != nil {
  3683  			i = s.expr(n.Low)
  3684  		}
  3685  		if n.High != nil {
  3686  			j = s.expr(n.High)
  3687  		}
  3688  		if n.Max != nil {
  3689  			k = s.expr(n.Max)
  3690  		}
  3691  		p, l, c := s.slice(v, i, j, k, n.Bounded())
  3692  		if check {
  3693  			// Emit checkptr instrumentation after bound check to prevent false positive, see #46938.
  3694  			s.checkPtrAlignment(n.X.(*ir.ConvExpr), v, s.conv(n.Max, k, k.Type, types.Types[types.TUINTPTR]))
  3695  		}
  3696  		return s.newValue3(ssaop.OpSliceMake, n.Type(), p, l, c)
  3697  
  3698  	case ir.OSLICESTR:
  3699  		n := n.(*ir.SliceExpr)
  3700  		v := s.expr(n.X)
  3701  		var i, j *ssa.Value
  3702  		if n.Low != nil {
  3703  			i = s.expr(n.Low)
  3704  		}
  3705  		if n.High != nil {
  3706  			j = s.expr(n.High)
  3707  		}
  3708  		p, l, _ := s.slice(v, i, j, nil, n.Bounded())
  3709  		return s.newValue2(ssaop.OpStringMake, n.Type(), p, l)
  3710  
  3711  	case ir.OSLICE2ARRPTR:
  3712  		// if arrlen > slice.len {
  3713  		//   panic(...)
  3714  		// }
  3715  		// slice.ptr
  3716  		n := n.(*ir.ConvExpr)
  3717  		v := s.expr(n.X)
  3718  		nelem := n.Type().Elem().NumElem()
  3719  		arrlen := s.constInt(types.Types[types.TINT], nelem)
  3720  		cap := s.newValue1(ssaop.OpSliceLen, types.Types[types.TINT], v)
  3721  		s.boundsCheck(arrlen, cap, ssa.BoundsConvert, false)
  3722  		op := ssaop.OpSlicePtr
  3723  		if nelem == 0 {
  3724  			op = ssaop.OpSlicePtrUnchecked
  3725  		}
  3726  		return s.newValue1(op, n.Type(), v)
  3727  
  3728  	case ir.OCALLFUNC:
  3729  		n := n.(*ir.CallExpr)
  3730  		if ir.IsIntrinsicCall(n) {
  3731  			return s.intrinsicCall(n)
  3732  		}
  3733  		fallthrough
  3734  
  3735  	case ir.OCALLINTER:
  3736  		n := n.(*ir.CallExpr)
  3737  		return s.callResult(n, callNormal)
  3738  
  3739  	case ir.OGETG:
  3740  		n := n.(*ir.CallExpr)
  3741  		return s.newValue1(ssaop.OpGetG, n.Type(), s.mem())
  3742  
  3743  	case ir.OGETCALLERSP:
  3744  		n := n.(*ir.CallExpr)
  3745  		return s.newValue1(ssaop.OpGetCallerSP, n.Type(), s.mem())
  3746  
  3747  	case ir.OAPPEND:
  3748  		return s.append(n.(*ir.CallExpr), false)
  3749  
  3750  	case ir.OMOVE2HEAP:
  3751  		return s.move2heap(n.(*ir.MoveToHeapExpr))
  3752  
  3753  	case ir.OMIN, ir.OMAX:
  3754  		return s.minMax(n.(*ir.CallExpr))
  3755  
  3756  	case ir.OSTRUCTLIT, ir.OARRAYLIT:
  3757  		// All literals with nonzero fields have already been
  3758  		// rewritten during walk. Any that remain are just T{}
  3759  		// or equivalents. Use the zero value.
  3760  		n := n.(*ir.CompLitExpr)
  3761  		if !ir.IsZero(n) {
  3762  			s.Fatalf("literal with nonzero value in SSA: %v", n)
  3763  		}
  3764  		return s.zeroVal(n.Type())
  3765  
  3766  	case ir.ONEW:
  3767  		n := n.(*ir.UnaryExpr)
  3768  		if x, ok := n.X.(*ir.DynamicType); ok && x.Op() == ir.ODYNAMICTYPE {
  3769  			return s.newObjectNonSpecialized(n.Type().Elem(), s.expr(x.RType))
  3770  		}
  3771  		return s.newObject(n.Type().Elem())
  3772  
  3773  	case ir.OUNSAFEADD:
  3774  		n := n.(*ir.BinaryExpr)
  3775  		ptr := s.expr(n.X)
  3776  		len := s.expr(n.Y)
  3777  
  3778  		// Force len to uintptr to prevent misuse of garbage bits in the
  3779  		// upper part of the register (#48536).
  3780  		len = s.conv(n, len, len.Type, types.Types[types.TUINTPTR])
  3781  
  3782  		return s.newValue2(ssaop.OpAddPtr, n.Type(), ptr, len)
  3783  
  3784  	default:
  3785  		s.Fatalf("unhandled expr %v", n.Op())
  3786  		return nil
  3787  	}
  3788  }
  3789  
  3790  func (s *state) resultOfCall(c *ssa.Value, which int64, t *types.Type) *ssa.Value {
  3791  	aux := c.Aux.(*ssa.AuxCall)
  3792  	pa := aux.ParamAssignmentForResult(which)
  3793  	// TODO(register args) determine if in-memory TypeOK is better loaded early from SelectNAddr or later when SelectN is expanded.
  3794  	// SelectN is better for pattern-matching and possible call-aware analysis we might want to do in the future.
  3795  	if len(pa.Registers) == 0 && !ssa.CanSSA(t) {
  3796  		addr := s.newValue1I(ssaop.OpSelectNAddr, types.NewPtr(t), which, c)
  3797  		return s.rawLoad(t, addr)
  3798  	}
  3799  	return s.newValue1I(ssaop.OpSelectN, t, which, c)
  3800  }
  3801  
  3802  func (s *state) resultAddrOfCall(c *ssa.Value, which int64, t *types.Type) *ssa.Value {
  3803  	aux := c.Aux.(*ssa.AuxCall)
  3804  	pa := aux.ParamAssignmentForResult(which)
  3805  	if len(pa.Registers) == 0 {
  3806  		return s.newValue1I(ssaop.OpSelectNAddr, types.NewPtr(t), which, c)
  3807  	}
  3808  	_, addr := s.temp(c.Pos, t)
  3809  	rval := s.newValue1I(ssaop.OpSelectN, t, which, c)
  3810  	s.vars[memVar] = s.newValue3Apos(ssaop.OpStore, types.TypeMem, t, addr, rval, s.mem(), false)
  3811  	return addr
  3812  }
  3813  
  3814  // Get backing store information for an append call.
  3815  func (s *state) getBackingStoreInfoForAppend(n *ir.CallExpr) *backingStoreInfo {
  3816  	if n.Esc() != ir.EscNone {
  3817  		return nil
  3818  	}
  3819  	return s.getBackingStoreInfo(n.Args[0])
  3820  }
  3821  func (s *state) getBackingStoreInfo(n ir.Node) *backingStoreInfo {
  3822  	t := n.Type()
  3823  	et := t.Elem()
  3824  	maxStackSize := int64(base.Debug.VariableMakeThreshold)
  3825  	if et.Size() == 0 || et.Size() > maxStackSize {
  3826  		return nil
  3827  	}
  3828  	if base.Flag.N != 0 {
  3829  		return nil
  3830  	}
  3831  	if !base.VariableMakeHash.MatchPos(n.Pos(), nil) {
  3832  		return nil
  3833  	}
  3834  	i := s.backingStores[n]
  3835  	if i != nil {
  3836  		return i
  3837  	}
  3838  
  3839  	// Build type of backing store.
  3840  	K := maxStackSize / et.Size() // rounds down
  3841  	KT := types.NewArray(et, K)
  3842  	KT.SetNoalg(true)
  3843  	types.CalcArraySize(KT)
  3844  	// Align more than naturally for the type KT. See issue 73199.
  3845  	align := types.NewArray(types.Types[types.TUINTPTR], 0)
  3846  	types.CalcArraySize(align)
  3847  	storeTyp := types.NewStruct([]*types.Field{
  3848  		{Sym: types.BlankSym, Type: align},
  3849  		{Sym: types.BlankSym, Type: KT},
  3850  	})
  3851  	storeTyp.SetNoalg(true)
  3852  	types.CalcStructSize(storeTyp)
  3853  
  3854  	// Make backing store variable.
  3855  	backingStore := typecheck.TempAt(n.Pos(), s.curfn, storeTyp)
  3856  	backingStore.SetAddrtaken(true)
  3857  
  3858  	// Make "used" boolean.
  3859  	used := typecheck.TempAt(n.Pos(), s.curfn, types.Types[types.TBOOL])
  3860  	if s.curBlock == s.f.Entry {
  3861  		s.vars[used] = s.constBool(false)
  3862  	} else {
  3863  		// initialize this variable at end of entry block
  3864  		s.defvars[s.f.Entry.ID][used] = s.constBool(false)
  3865  	}
  3866  
  3867  	// Initialize an info structure.
  3868  	if s.backingStores == nil {
  3869  		s.backingStores = map[ir.Node]*backingStoreInfo{}
  3870  	}
  3871  	i = &backingStoreInfo{K: K, store: backingStore, used: used, usedStatic: false}
  3872  	s.backingStores[n] = i
  3873  	return i
  3874  }
  3875  
  3876  // append converts an OAPPEND node to SSA.
  3877  // If inplace is false, it converts the OAPPEND expression n to an ssa.Value,
  3878  // adds it to s, and returns the Value.
  3879  // If inplace is true, it writes the result of the OAPPEND expression n
  3880  // back to the slice being appended to, and returns nil.
  3881  // inplace MUST be set to false if the slice can be SSA'd.
  3882  // Note: this code only handles fixed-count appends. Dotdotdot appends
  3883  // have already been rewritten at this point (by walk).
  3884  func (s *state) append(n *ir.CallExpr, inplace bool) *ssa.Value {
  3885  	// If inplace is false, process as expression "append(s, e1, e2, e3)":
  3886  	//
  3887  	// ptr, len, cap := s
  3888  	// len += 3
  3889  	// if uint(len) > uint(cap) {
  3890  	//     ptr, len, cap = growslice(ptr, len, cap, 3, typ)
  3891  	//     Note that len is unmodified by growslice.
  3892  	// }
  3893  	// // with write barriers, if needed:
  3894  	// *(ptr+(len-3)) = e1
  3895  	// *(ptr+(len-2)) = e2
  3896  	// *(ptr+(len-1)) = e3
  3897  	// return makeslice(ptr, len, cap)
  3898  	//
  3899  	//
  3900  	// If inplace is true, process as statement "s = append(s, e1, e2, e3)":
  3901  	//
  3902  	// a := &s
  3903  	// ptr, len, cap := s
  3904  	// len += 3
  3905  	// if uint(len) > uint(cap) {
  3906  	//    ptr, len, cap = growslice(ptr, len, cap, 3, typ)
  3907  	//    vardef(a)    // if necessary, advise liveness we are writing a new a
  3908  	//    *a.cap = cap // write before ptr to avoid a spill
  3909  	//    *a.ptr = ptr // with write barrier
  3910  	// }
  3911  	// *a.len = len
  3912  	// // with write barriers, if needed:
  3913  	// *(ptr+(len-3)) = e1
  3914  	// *(ptr+(len-2)) = e2
  3915  	// *(ptr+(len-1)) = e3
  3916  
  3917  	et := n.Type().Elem()
  3918  	pt := types.NewPtr(et)
  3919  
  3920  	// Evaluate slice
  3921  	sn := n.Args[0] // the slice node is the first in the list
  3922  	var slice, addr *ssa.Value
  3923  	if inplace {
  3924  		addr = s.addr(sn)
  3925  		slice = s.load(n.Type(), addr)
  3926  	} else {
  3927  		slice = s.expr(sn)
  3928  	}
  3929  
  3930  	// Allocate new blocks
  3931  	grow := s.f.NewBlock(block.BlockPlain)
  3932  	assign := s.f.NewBlock(block.BlockPlain)
  3933  
  3934  	// Decomposse input slice.
  3935  	p := s.newValue1(ssaop.OpSlicePtr, pt, slice)
  3936  	l := s.newValue1(ssaop.OpSliceLen, types.Types[types.TINT], slice)
  3937  	c := s.newValue1(ssaop.OpSliceCap, types.Types[types.TINT], slice)
  3938  
  3939  	// Add number of new elements to length.
  3940  	nargs := s.constInt(types.Types[types.TINT], int64(len(n.Args)-1))
  3941  	oldLen := l
  3942  	l = s.newValue2(s.ssaOp(ir.OADD, types.Types[types.TINT]), types.Types[types.TINT], l, nargs)
  3943  
  3944  	// Decide if we need to grow
  3945  	cmp := s.newValue2(s.ssaOp(ir.OLT, types.Types[types.TUINT]), types.Types[types.TBOOL], c, l)
  3946  
  3947  	// Record values of ptr/len/cap before branch.
  3948  	s.vars[ptrVar] = p
  3949  	s.vars[lenVar] = l
  3950  	if !inplace {
  3951  		s.vars[capVar] = c
  3952  	}
  3953  
  3954  	b := s.endBlock()
  3955  	b.Kind = block.BlockIf
  3956  	b.Likely = ssa.BranchUnlikely
  3957  	b.SetControl(cmp)
  3958  	b.AddEdgeTo(grow)
  3959  	b.AddEdgeTo(assign)
  3960  
  3961  	// If the result of the append does not escape, we can use
  3962  	// a stack-allocated backing store if len is small enough.
  3963  	// A stack-allocated backing store could be used at every
  3964  	// append that qualifies, but we limit it in some cases to
  3965  	// avoid wasted code and stack space.
  3966  	//
  3967  	// Note that we have two different strategies.
  3968  	// 1. The standard strategy is just to allocate the full
  3969  	//    backing store at the first append.
  3970  	// 2. An alternate strategy is used when
  3971  	//        a. The backing store eventually escapes via move2heap
  3972  	//    and b. The capacity is used somehow
  3973  	//    In this case, we don't want to just allocate
  3974  	//    the full buffer at the first append, because when
  3975  	//    we move2heap the buffer to the heap when it escapes,
  3976  	//    we might end up wasting memory because we can't
  3977  	//    change the capacity.
  3978  	//    So in this case we use growsliceBuf to reuse the buffer
  3979  	//    and walk one step up the size class ladder each time.
  3980  	//
  3981  	// TODO: handle ... append case? Currently we handle only
  3982  	// a fixed number of appended elements.
  3983  	var info *backingStoreInfo
  3984  	if !inplace {
  3985  		info = s.getBackingStoreInfoForAppend(n)
  3986  	}
  3987  
  3988  	if !inplace && info != nil && !n.UseBuf && !info.usedStatic {
  3989  		// if l <= K {
  3990  		//   if !used {
  3991  		//     if oldLen == 0 {
  3992  		//       var store [K]T
  3993  		//       s = store[:l:K]
  3994  		//       used = true
  3995  		//     }
  3996  		//   }
  3997  		// }
  3998  		// ... if we didn't use the stack backing store, call growslice ...
  3999  		//
  4000  		// oldLen==0 is not strictly necessary, but requiring it means
  4001  		// we don't have to worry about copying existing elements.
  4002  		// Allowing oldLen>0 would add complication. Worth it? I would guess not.
  4003  		//
  4004  		// TODO: instead of the used boolean, we could insist that this only applies
  4005  		// to monotonic slices, those which once they have >0 entries never go back
  4006  		// to 0 entries. Then oldLen==0 is enough.
  4007  		//
  4008  		// We also do this for append(x, ...) once for every x.
  4009  		// It is ok to do it more often, but it is probably helpful only for
  4010  		// the first instance. TODO: this could use more tuning. Using ir.Node
  4011  		// as the key works for *ir.Name instances but probably nothing else.
  4012  		info.usedStatic = true
  4013  		// TODO: unset usedStatic somehow?
  4014  
  4015  		usedTestBlock := s.f.NewBlock(block.BlockPlain)
  4016  		oldLenTestBlock := s.f.NewBlock(block.BlockPlain)
  4017  		bodyBlock := s.f.NewBlock(block.BlockPlain)
  4018  		growSlice := s.f.NewBlock(block.BlockPlain)
  4019  		tInt := types.Types[types.TINT]
  4020  		tBool := types.Types[types.TBOOL]
  4021  
  4022  		// if l <= K
  4023  		s.startBlock(grow)
  4024  		kTest := s.newValue2(s.ssaOp(ir.OLE, tInt), tBool, l, s.constInt(tInt, info.K))
  4025  		b := s.endBlock()
  4026  		b.Kind = block.BlockIf
  4027  		b.SetControl(kTest)
  4028  		b.AddEdgeTo(usedTestBlock)
  4029  		b.AddEdgeTo(growSlice)
  4030  		b.Likely = ssa.BranchLikely
  4031  
  4032  		// if !used
  4033  		s.startBlock(usedTestBlock)
  4034  		usedTest := s.newValue1(ssaop.OpNot, tBool, s.expr(info.used))
  4035  		b = s.endBlock()
  4036  		b.Kind = block.BlockIf
  4037  		b.SetControl(usedTest)
  4038  		b.AddEdgeTo(oldLenTestBlock)
  4039  		b.AddEdgeTo(growSlice)
  4040  		b.Likely = ssa.BranchLikely
  4041  
  4042  		// if oldLen == 0
  4043  		s.startBlock(oldLenTestBlock)
  4044  		oldLenTest := s.newValue2(s.ssaOp(ir.OEQ, tInt), tBool, oldLen, s.constInt(tInt, 0))
  4045  		b = s.endBlock()
  4046  		b.Kind = block.BlockIf
  4047  		b.SetControl(oldLenTest)
  4048  		b.AddEdgeTo(bodyBlock)
  4049  		b.AddEdgeTo(growSlice)
  4050  		b.Likely = ssa.BranchLikely
  4051  
  4052  		// var store struct { _ [0]uintptr; arr [K]T }
  4053  		s.startBlock(bodyBlock)
  4054  		if et.HasPointers() {
  4055  			s.vars[memVar] = s.newValue1A(ssaop.OpVarDef, types.TypeMem, info.store, s.mem())
  4056  		}
  4057  		addr := s.addr(info.store)
  4058  		s.zero(info.store.Type(), addr)
  4059  
  4060  		// s = store.arr[:l:K]
  4061  		s.vars[ptrVar] = addr
  4062  		s.vars[lenVar] = l // nargs would also be ok because of the oldLen==0 test.
  4063  		s.vars[capVar] = s.constInt(tInt, info.K)
  4064  
  4065  		// used = true
  4066  		s.assign(info.used, s.constBool(true), false, 0)
  4067  		b = s.endBlock()
  4068  		b.AddEdgeTo(assign)
  4069  
  4070  		// New block to use for growslice call.
  4071  		grow = growSlice
  4072  	}
  4073  
  4074  	// Call growslice
  4075  	s.startBlock(grow)
  4076  	taddr := s.expr(n.Fun)
  4077  	var r []*ssa.Value
  4078  	if info != nil && n.UseBuf {
  4079  		// Use stack-allocated buffer as backing store, if we can.
  4080  		if et.HasPointers() && !info.usedStatic {
  4081  			// Initialize in the function header. Not the best place,
  4082  			// but it makes sure we don't scan this area before it is
  4083  			// initialized.
  4084  			mem := s.defvars[s.f.Entry.ID][memVar]
  4085  			mem = s.f.Entry.NewValue1A(n.Pos(), ssaop.OpVarDef, types.TypeMem, info.store, mem)
  4086  			addr := s.f.Entry.NewValue2A(n.Pos(), ssaop.OpLocalAddr, types.NewPtr(info.store.Type()), info.store, s.sp, mem)
  4087  			mem = s.f.Entry.NewValue2I(n.Pos(), ssaop.OpZero, types.TypeMem, info.store.Type().Size(), addr, mem)
  4088  			mem.Aux = info.store.Type()
  4089  			s.defvars[s.f.Entry.ID][memVar] = mem
  4090  			info.usedStatic = true
  4091  		}
  4092  		fn := ir.Syms.GrowsliceBuf
  4093  		if goexperiment.RuntimeFreegc && n.AppendNoAlias && !et.HasPointers() {
  4094  			// The append is for a non-aliased slice where the runtime knows how to free
  4095  			// the old logically dead backing store after growth.
  4096  			// TODO(thepudds): for now, we only use the NoAlias version for element types
  4097  			// without pointers while waiting on additional runtime support (CL 698515).
  4098  			fn = ir.Syms.GrowsliceBufNoAlias
  4099  		}
  4100  		r = s.rtcall(fn, true, []*types.Type{n.Type()}, p, l, c, nargs, taddr, s.addr(info.store), s.constInt(types.Types[types.TINT], info.K))
  4101  	} else {
  4102  		fn := ir.Syms.Growslice
  4103  		if goexperiment.RuntimeFreegc && n.AppendNoAlias && !et.HasPointers() {
  4104  			// The append is for a non-aliased slice where the runtime knows how to free
  4105  			// the old logically dead backing store after growth.
  4106  			// TODO(thepudds): for now, we only use the NoAlias version for element types
  4107  			// without pointers while waiting on additional runtime support (CL 698515).
  4108  			fn = ir.Syms.GrowsliceNoAlias
  4109  		}
  4110  		r = s.rtcall(fn, true, []*types.Type{n.Type()}, p, l, c, nargs, taddr)
  4111  	}
  4112  
  4113  	// Decompose output slice
  4114  	p = s.newValue1(ssaop.OpSlicePtr, pt, r[0])
  4115  	l = s.newValue1(ssaop.OpSliceLen, types.Types[types.TINT], r[0])
  4116  	c = s.newValue1(ssaop.OpSliceCap, types.Types[types.TINT], r[0])
  4117  
  4118  	s.vars[ptrVar] = p
  4119  	s.vars[lenVar] = l
  4120  	s.vars[capVar] = c
  4121  	if inplace {
  4122  		if sn.Op() == ir.ONAME {
  4123  			sn := sn.(*ir.Name)
  4124  			if sn.Class != ir.PEXTERN {
  4125  				// Tell liveness we're about to build a new slice
  4126  				s.vars[memVar] = s.newValue1A(ssaop.OpVarDef, types.TypeMem, sn, s.mem())
  4127  			}
  4128  		}
  4129  		capaddr := s.newValue1I(ssaop.OpOffPtr, s.f.Config.Types.IntPtr, types.SliceCapOffset, addr)
  4130  		s.store(types.Types[types.TINT], capaddr, c)
  4131  		s.store(pt, addr, p)
  4132  	}
  4133  
  4134  	b = s.endBlock()
  4135  	b.AddEdgeTo(assign)
  4136  
  4137  	// assign new elements to slots
  4138  	s.startBlock(assign)
  4139  	p = s.variable(ptrVar, pt)                      // generates phi for ptr
  4140  	l = s.variable(lenVar, types.Types[types.TINT]) // generates phi for len
  4141  	if !inplace {
  4142  		c = s.variable(capVar, types.Types[types.TINT]) // generates phi for cap
  4143  	}
  4144  
  4145  	if inplace {
  4146  		// Update length in place.
  4147  		// We have to wait until here to make sure growslice succeeded.
  4148  		lenaddr := s.newValue1I(ssaop.OpOffPtr, s.f.Config.Types.IntPtr, types.SliceLenOffset, addr)
  4149  		s.store(types.Types[types.TINT], lenaddr, l)
  4150  	}
  4151  
  4152  	// Evaluate args
  4153  	type argRec struct {
  4154  		// if store is true, we're appending the value v.  If false, we're appending the
  4155  		// value at *v.
  4156  		v     *ssa.Value
  4157  		store bool
  4158  	}
  4159  	args := make([]argRec, 0, len(n.Args[1:]))
  4160  	for _, n := range n.Args[1:] {
  4161  		if ssa.CanSSA(n.Type()) {
  4162  			args = append(args, argRec{v: s.expr(n), store: true})
  4163  		} else {
  4164  			v := s.addr(n)
  4165  			args = append(args, argRec{v: v})
  4166  		}
  4167  	}
  4168  
  4169  	// Write args into slice.
  4170  	oldLen = s.newValue2(s.ssaOp(ir.OSUB, types.Types[types.TINT]), types.Types[types.TINT], l, nargs)
  4171  	p2 := s.newValue2(ssaop.OpPtrIndex, pt, p, oldLen)
  4172  	for i, arg := range args {
  4173  		addr := s.newValue2(ssaop.OpPtrIndex, pt, p2, s.constInt(types.Types[types.TINT], int64(i)))
  4174  		if arg.store {
  4175  			s.storeType(et, addr, arg.v, 0, true)
  4176  		} else {
  4177  			s.move(et, addr, arg.v)
  4178  		}
  4179  	}
  4180  
  4181  	// The following deletions have no practical effect at this time
  4182  	// because state.vars has been reset by the preceding state.startBlock.
  4183  	// They only enforce the fact that these variables are no longer need in
  4184  	// the current scope.
  4185  	delete(s.vars, ptrVar)
  4186  	delete(s.vars, lenVar)
  4187  	if !inplace {
  4188  		delete(s.vars, capVar)
  4189  	}
  4190  
  4191  	// make result
  4192  	if inplace {
  4193  		return nil
  4194  	}
  4195  	return s.newValue3(ssaop.OpSliceMake, n.Type(), p, l, c)
  4196  }
  4197  
  4198  func (s *state) move2heap(n *ir.MoveToHeapExpr) *ssa.Value {
  4199  	// s := n.Slice
  4200  	// if s.ptr points to current stack frame {
  4201  	//     s2 := make([]T, s.len, s.cap)
  4202  	//     copy(s2[:cap], s[:cap])
  4203  	//     s = s2
  4204  	// }
  4205  	// return s
  4206  
  4207  	slice := s.expr(n.Slice)
  4208  	et := slice.Type.Elem()
  4209  	pt := types.NewPtr(et)
  4210  
  4211  	info := s.getBackingStoreInfo(n)
  4212  	if info == nil {
  4213  		// Backing store will never be stack allocated, so
  4214  		// move2heap is a no-op.
  4215  		return slice
  4216  	}
  4217  
  4218  	// Decomposse input slice.
  4219  	p := s.newValue1(ssaop.OpSlicePtr, pt, slice)
  4220  	l := s.newValue1(ssaop.OpSliceLen, types.Types[types.TINT], slice)
  4221  	c := s.newValue1(ssaop.OpSliceCap, types.Types[types.TINT], slice)
  4222  
  4223  	moveBlock := s.f.NewBlock(block.BlockPlain)
  4224  	mergeBlock := s.f.NewBlock(block.BlockPlain)
  4225  
  4226  	s.vars[ptrVar] = p
  4227  	s.vars[lenVar] = l
  4228  	s.vars[capVar] = c
  4229  
  4230  	// Decide if we need to move the slice backing store.
  4231  	// It needs to be moved if it is currently on the stack.
  4232  	sub := ssaop.OpSub64
  4233  	less := ssaop.OpLess64U
  4234  	if s.config.PtrSize == 4 {
  4235  		sub = ssaop.OpSub32
  4236  		less = ssaop.OpLess32U
  4237  	}
  4238  	callerSP := s.newValue1(ssaop.OpGetCallerSP, types.Types[types.TUINTPTR], s.mem())
  4239  	frameSize := s.newValue2(sub, types.Types[types.TUINTPTR], callerSP, s.sp)
  4240  	pInt := s.newValue2(ssaop.OpConvert, types.Types[types.TUINTPTR], p, s.mem())
  4241  	off := s.newValue2(sub, types.Types[types.TUINTPTR], pInt, s.sp)
  4242  	cond := s.newValue2(less, types.Types[types.TBOOL], off, frameSize)
  4243  
  4244  	b := s.endBlock()
  4245  	b.Kind = block.BlockIf
  4246  	b.Likely = ssa.BranchUnlikely // fast path is to not have to call into runtime
  4247  	b.SetControl(cond)
  4248  	b.AddEdgeTo(moveBlock)
  4249  	b.AddEdgeTo(mergeBlock)
  4250  
  4251  	// Move the slice to heap
  4252  	s.startBlock(moveBlock)
  4253  	var newSlice *ssa.Value
  4254  	if et.HasPointers() {
  4255  		typ := s.expr(n.RType)
  4256  		if n.PreserveCapacity {
  4257  			newSlice = s.rtcall(ir.Syms.MoveSlice, true, []*types.Type{slice.Type}, typ, p, l, c)[0]
  4258  		} else {
  4259  			newSlice = s.rtcall(ir.Syms.MoveSliceNoCap, true, []*types.Type{slice.Type}, typ, p, l)[0]
  4260  		}
  4261  	} else {
  4262  		elemSize := s.constInt(types.Types[types.TUINTPTR], et.Size())
  4263  		if n.PreserveCapacity {
  4264  			newSlice = s.rtcall(ir.Syms.MoveSliceNoScan, true, []*types.Type{slice.Type}, elemSize, p, l, c)[0]
  4265  		} else {
  4266  			newSlice = s.rtcall(ir.Syms.MoveSliceNoCapNoScan, true, []*types.Type{slice.Type}, elemSize, p, l)[0]
  4267  		}
  4268  	}
  4269  	// Decompose output slice
  4270  	s.vars[ptrVar] = s.newValue1(ssaop.OpSlicePtr, pt, newSlice)
  4271  	s.vars[lenVar] = s.newValue1(ssaop.OpSliceLen, types.Types[types.TINT], newSlice)
  4272  	s.vars[capVar] = s.newValue1(ssaop.OpSliceCap, types.Types[types.TINT], newSlice)
  4273  	b = s.endBlock()
  4274  	b.AddEdgeTo(mergeBlock)
  4275  
  4276  	// Merge fast path (no moving) and slow path (moved)
  4277  	s.startBlock(mergeBlock)
  4278  	p = s.variable(ptrVar, pt)                      // generates phi for ptr
  4279  	l = s.variable(lenVar, types.Types[types.TINT]) // generates phi for len
  4280  	c = s.variable(capVar, types.Types[types.TINT]) // generates phi for cap
  4281  	delete(s.vars, ptrVar)
  4282  	delete(s.vars, lenVar)
  4283  	delete(s.vars, capVar)
  4284  	return s.newValue3(ssaop.OpSliceMake, slice.Type, p, l, c)
  4285  }
  4286  
  4287  // minMax converts an OMIN/OMAX builtin call into SSA.
  4288  func (s *state) minMax(n *ir.CallExpr) *ssa.Value {
  4289  	// The OMIN/OMAX builtin is variadic, but its semantics are
  4290  	// equivalent to left-folding a binary min/max operation across the
  4291  	// arguments list.
  4292  	fold := func(op func(x, a *ssa.Value) *ssa.Value) *ssa.Value {
  4293  		x := s.expr(n.Args[0])
  4294  		for _, arg := range n.Args[1:] {
  4295  			x = op(x, s.expr(arg))
  4296  		}
  4297  		return x
  4298  	}
  4299  
  4300  	typ := n.Type()
  4301  
  4302  	if typ.IsFloat() || typ.IsString() {
  4303  		// min/max semantics for floats are tricky because of NaNs and
  4304  		// negative zero. Some architectures have instructions which
  4305  		// we can use to generate the right result. For others we must
  4306  		// call into the runtime instead.
  4307  		//
  4308  		// Strings are conceptually simpler, but we currently desugar
  4309  		// string comparisons during walk, not ssagen.
  4310  
  4311  		if typ.IsFloat() {
  4312  			hasIntrinsic := false
  4313  			switch Arch.LinkArch.Family {
  4314  			case sys.AMD64, sys.ARM64, sys.Loong64, sys.RISCV64:
  4315  				hasIntrinsic = true
  4316  			case sys.PPC64:
  4317  				hasIntrinsic = buildcfg.GOPPC64 >= 9
  4318  			case sys.S390X:
  4319  				// FIXME: add check once GOS390X exists
  4320  			}
  4321  
  4322  			if hasIntrinsic {
  4323  				var op ssaop.Op
  4324  				switch {
  4325  				case typ.Kind() == types.TFLOAT64 && n.Op() == ir.OMIN:
  4326  					op = ssaop.OpMin64F
  4327  				case typ.Kind() == types.TFLOAT64 && n.Op() == ir.OMAX:
  4328  					op = ssaop.OpMax64F
  4329  				case typ.Kind() == types.TFLOAT32 && n.Op() == ir.OMIN:
  4330  					op = ssaop.OpMin32F
  4331  				case typ.Kind() == types.TFLOAT32 && n.Op() == ir.OMAX:
  4332  					op = ssaop.OpMax32F
  4333  				}
  4334  				return fold(func(x, a *ssa.Value) *ssa.Value {
  4335  					return s.newValue2(op, typ, x, a)
  4336  				})
  4337  			}
  4338  		}
  4339  		var name string
  4340  		switch typ.Kind() {
  4341  		case types.TFLOAT32:
  4342  			switch n.Op() {
  4343  			case ir.OMIN:
  4344  				name = "fmin32"
  4345  			case ir.OMAX:
  4346  				name = "fmax32"
  4347  			}
  4348  		case types.TFLOAT64:
  4349  			switch n.Op() {
  4350  			case ir.OMIN:
  4351  				name = "fmin64"
  4352  			case ir.OMAX:
  4353  				name = "fmax64"
  4354  			}
  4355  		case types.TSTRING:
  4356  			switch n.Op() {
  4357  			case ir.OMIN:
  4358  				name = "strmin"
  4359  			case ir.OMAX:
  4360  				name = "strmax"
  4361  			}
  4362  		}
  4363  		fn := typecheck.LookupRuntimeFunc(name)
  4364  
  4365  		return fold(func(x, a *ssa.Value) *ssa.Value {
  4366  			return s.rtcall(fn, true, []*types.Type{typ}, x, a)[0]
  4367  		})
  4368  	}
  4369  
  4370  	if typ.IsInteger() {
  4371  		if Arch.LinkArch.Family == sys.RISCV64 && buildcfg.GORISCV64 >= 22 && typ.Size() == 8 {
  4372  			var op ssaop.Op
  4373  			switch {
  4374  			case typ.IsSigned() && n.Op() == ir.OMIN:
  4375  				op = ssaop.OpMin64
  4376  			case typ.IsSigned() && n.Op() == ir.OMAX:
  4377  				op = ssaop.OpMax64
  4378  			case typ.IsUnsigned() && n.Op() == ir.OMIN:
  4379  				op = ssaop.OpMin64u
  4380  			case typ.IsUnsigned() && n.Op() == ir.OMAX:
  4381  				op = ssaop.OpMax64u
  4382  			}
  4383  			return fold(func(x, a *ssa.Value) *ssa.Value {
  4384  				return s.newValue2(op, typ, x, a)
  4385  			})
  4386  		}
  4387  	}
  4388  
  4389  	lt := s.ssaOp(ir.OLT, typ)
  4390  
  4391  	return fold(func(x, a *ssa.Value) *ssa.Value {
  4392  		switch n.Op() {
  4393  		case ir.OMIN:
  4394  			// a < x ? a : x
  4395  			return s.ternary(s.newValue2(lt, types.Types[types.TBOOL], a, x), a, x)
  4396  		case ir.OMAX:
  4397  			// x < a ? a : x
  4398  			return s.ternary(s.newValue2(lt, types.Types[types.TBOOL], x, a), a, x)
  4399  		}
  4400  		panic("unreachable")
  4401  	})
  4402  }
  4403  
  4404  // ternary emits code to evaluate cond ? x : y.
  4405  func (s *state) ternary(cond, x, y *ssa.Value) *ssa.Value {
  4406  	// Note that we need a new ternaryVar each time (unlike okVar where we can
  4407  	// reuse the variable) because it might have a different type every time.
  4408  	ternaryVar := ssaMarker("ternary")
  4409  
  4410  	bThen := s.f.NewBlock(block.BlockPlain)
  4411  	bElse := s.f.NewBlock(block.BlockPlain)
  4412  	bEnd := s.f.NewBlock(block.BlockPlain)
  4413  
  4414  	b := s.endBlock()
  4415  	b.Kind = block.BlockIf
  4416  	b.SetControl(cond)
  4417  	b.AddEdgeTo(bThen)
  4418  	b.AddEdgeTo(bElse)
  4419  
  4420  	s.startBlock(bThen)
  4421  	s.vars[ternaryVar] = x
  4422  	s.endBlock().AddEdgeTo(bEnd)
  4423  
  4424  	s.startBlock(bElse)
  4425  	s.vars[ternaryVar] = y
  4426  	s.endBlock().AddEdgeTo(bEnd)
  4427  
  4428  	s.startBlock(bEnd)
  4429  	r := s.variable(ternaryVar, x.Type)
  4430  	delete(s.vars, ternaryVar)
  4431  	return r
  4432  }
  4433  
  4434  // condBranch evaluates the boolean expression cond and branches to yes
  4435  // if cond is true and no if cond is false.
  4436  // This function is intended to handle && and || better than just calling
  4437  // s.expr(cond) and branching on the result.
  4438  func (s *state) condBranch(cond ir.Node, yes, no *ssa.Block, likely int8) {
  4439  	switch cond.Op() {
  4440  	case ir.OANDAND:
  4441  		cond := cond.(*ir.LogicalExpr)
  4442  		mid := s.f.NewBlock(block.BlockPlain)
  4443  		s.stmtList(cond.Init())
  4444  		s.condBranch(cond.X, mid, no, max(likely, 0))
  4445  		s.startBlock(mid)
  4446  		s.condBranch(cond.Y, yes, no, likely)
  4447  		return
  4448  		// Note: if likely==1, then both recursive calls pass 1.
  4449  		// If likely==-1, then we don't have enough information to decide
  4450  		// whether the first branch is likely or not. So we pass 0 for
  4451  		// the likeliness of the first branch.
  4452  		// TODO: have the frontend give us branch prediction hints for
  4453  		// OANDAND and OOROR nodes (if it ever has such info).
  4454  	case ir.OOROR:
  4455  		cond := cond.(*ir.LogicalExpr)
  4456  		mid := s.f.NewBlock(block.BlockPlain)
  4457  		s.stmtList(cond.Init())
  4458  		s.condBranch(cond.X, yes, mid, min(likely, 0))
  4459  		s.startBlock(mid)
  4460  		s.condBranch(cond.Y, yes, no, likely)
  4461  		return
  4462  		// Note: if likely==-1, then both recursive calls pass -1.
  4463  		// If likely==1, then we don't have enough info to decide
  4464  		// the likelihood of the first branch.
  4465  	case ir.ONOT:
  4466  		cond := cond.(*ir.UnaryExpr)
  4467  		s.stmtList(cond.Init())
  4468  		s.condBranch(cond.X, no, yes, -likely)
  4469  		return
  4470  	case ir.OCONVNOP:
  4471  		cond := cond.(*ir.ConvExpr)
  4472  		s.stmtList(cond.Init())
  4473  		s.condBranch(cond.X, yes, no, likely)
  4474  		return
  4475  	}
  4476  	c := s.expr(cond)
  4477  	b := s.endBlock()
  4478  	b.Kind = block.BlockIf
  4479  	b.SetControl(c)
  4480  	b.Likely = ssa.BranchPrediction(likely) // gc and ssa both use -1/0/+1 for likeliness
  4481  	b.AddEdgeTo(yes)
  4482  	b.AddEdgeTo(no)
  4483  }
  4484  
  4485  type skipMask uint8
  4486  
  4487  const (
  4488  	skipPtr skipMask = 1 << iota
  4489  	skipLen
  4490  	skipCap
  4491  )
  4492  
  4493  // assign does left = right.
  4494  // Right has already been evaluated to ssa, left has not.
  4495  // If deref is true, then we do left = *right instead (and right has already been nil-checked).
  4496  // If deref is true and right == nil, just do left = 0.
  4497  // skip indicates assignments (at the top level) that can be avoided.
  4498  // mayOverlap indicates whether left&right might partially overlap in memory. Default is false.
  4499  func (s *state) assign(left ir.Node, right *ssa.Value, deref bool, skip skipMask) {
  4500  	s.assignWhichMayOverlap(left, right, deref, skip, false)
  4501  }
  4502  func (s *state) assignWhichMayOverlap(left ir.Node, right *ssa.Value, deref bool, skip skipMask, mayOverlap bool) {
  4503  	if left.Op() == ir.ONAME && ir.IsBlank(left) {
  4504  		return
  4505  	}
  4506  	t := left.Type()
  4507  	types.CalcSize(t)
  4508  	if s.canSSA(left) {
  4509  		if deref {
  4510  			s.Fatalf("can SSA LHS %v but not RHS %s", left, right)
  4511  		}
  4512  		if left.Op() == ir.ODOT {
  4513  			// We're assigning to a field of an ssa-able value.
  4514  			// We need to build a new structure with the new value for the
  4515  			// field we're assigning and the old values for the other fields.
  4516  			// For instance:
  4517  			//   type T struct {a, b, c int}
  4518  			//   var T x
  4519  			//   x.b = 5
  4520  			// For the x.b = 5 assignment we want to generate x = T{x.a, 5, x.c}
  4521  
  4522  			// Grab information about the structure type.
  4523  			left := left.(*ir.SelectorExpr)
  4524  			t := left.X.Type()
  4525  			nf := t.NumFields()
  4526  			idx := fieldIdx(left)
  4527  
  4528  			// Grab old value of structure.
  4529  			old := s.expr(left.X)
  4530  
  4531  			if left.Type().Size() == 0 {
  4532  				// Nothing to do when assigning zero-sized things.
  4533  				return
  4534  			}
  4535  
  4536  			// Make new structure.
  4537  			new := s.newValue0(ssaop.OpStructMake, t)
  4538  
  4539  			// Add fields as args.
  4540  			for i := 0; i < nf; i++ {
  4541  				if i == idx {
  4542  					new.AddArg(right)
  4543  				} else {
  4544  					new.AddArg(s.newValue1I(ssaop.OpStructSelect, t.FieldType(i), int64(i), old))
  4545  				}
  4546  			}
  4547  
  4548  			// Recursively assign the new value we've made to the base of the dot op.
  4549  			s.assign(left.X, new, false, 0)
  4550  			// TODO: do we need to update named values here?
  4551  			return
  4552  		}
  4553  		if left.Op() == ir.OINDEX && left.(*ir.IndexExpr).X.Type().IsArray() {
  4554  			left := left.(*ir.IndexExpr)
  4555  			s.pushLine(left.Pos())
  4556  			defer s.popLine()
  4557  			// We're assigning to an element of an ssa-able array.
  4558  			// a[i] = v
  4559  			t := left.X.Type()
  4560  			n := t.NumElem()
  4561  
  4562  			i := s.expr(left.Index) // index
  4563  			if n == 0 {
  4564  				_ = s.expr(left.X) // Evaluating left.X for any side-effects.
  4565  				// The bounds check must fail.  Might as well
  4566  				// ignore the actual index and just use zeros.
  4567  				z := s.constInt(types.Types[types.TINT], 0)
  4568  				s.boundsCheck(z, z, ssa.BoundsIndex, false)
  4569  				return
  4570  			}
  4571  			if t.Size() == 0 {
  4572  				_ = s.expr(left.X) // Evaluating left.X for any side-effects.
  4573  				// Generate bounds check for left, since this can happen
  4574  				// for 0-size assignment case, see issue #79236.
  4575  				len := s.constInt(types.Types[types.TINT], n)
  4576  				s.boundsCheck(i, len, ssa.BoundsIndex, false)
  4577  				return
  4578  			}
  4579  			if n != 1 {
  4580  				// This can happen in weird, always-panics cases, like:
  4581  				//     var x [0][2]int
  4582  				//     x[i][j] = 5
  4583  				// We know it always panics because the LHS is ssa-able,
  4584  				// and arrays of length > 1 can't be ssa-able unless
  4585  				// they are somewhere inside an outer [0].
  4586  				// We can ignore the actual assignment, it is dynamically
  4587  				// unreachable. See issue 77635.
  4588  				// Still, evaluating left.X for any side-effects.
  4589  				_ = s.expr(left.X)
  4590  				return
  4591  			}
  4592  
  4593  			// Rewrite to a = [1]{v}
  4594  			len := s.constInt(types.Types[types.TINT], 1)
  4595  			s.boundsCheck(i, len, ssa.BoundsIndex, false) // checks i == 0
  4596  			v := s.newValue1(ssaop.OpArrayMake1, t, right)
  4597  			s.assign(left.X, v, false, 0)
  4598  			return
  4599  		}
  4600  		left := left.(*ir.Name)
  4601  		// Update variable assignment.
  4602  		s.vars[left] = right
  4603  		s.addNamedValue(left, right)
  4604  		return
  4605  	}
  4606  
  4607  	// If this assignment clobbers an entire local variable, then emit
  4608  	// OpVarDef so liveness analysis knows the variable is redefined.
  4609  	if base, ok := clobberBase(left).(*ir.Name); ok && base.OnStack() && skip == 0 && (t.HasPointers() || ssa.IsMergeCandidate(base)) {
  4610  		s.vars[memVar] = s.newValue1Apos(ssaop.OpVarDef, types.TypeMem, base, s.mem(), !ir.IsAutoTmp(base))
  4611  	}
  4612  
  4613  	// Left is not ssa-able. Compute its address.
  4614  	addr := s.addr(left)
  4615  	if ir.IsReflectHeaderDataField(left) {
  4616  		// Package unsafe's documentation says storing pointers into
  4617  		// reflect.SliceHeader and reflect.StringHeader's Data fields
  4618  		// is valid, even though they have type uintptr (#19168).
  4619  		// Mark it pointer type to signal the writebarrier pass to
  4620  		// insert a write barrier.
  4621  		t = types.Types[types.TUNSAFEPTR]
  4622  	}
  4623  	if deref {
  4624  		// Treat as a mem->mem move.
  4625  		if right == nil {
  4626  			s.zero(t, addr)
  4627  		} else {
  4628  			s.moveWhichMayOverlap(t, addr, right, mayOverlap)
  4629  		}
  4630  		return
  4631  	}
  4632  	// Treat as a store.
  4633  	s.storeType(t, addr, right, skip, !ir.IsAutoTmp(left))
  4634  }
  4635  
  4636  // zeroVal returns the zero value for type t.
  4637  func (s *state) zeroVal(t *types.Type) *ssa.Value {
  4638  	if t.Size() == 0 {
  4639  		return s.entryNewValue0(ssaop.OpEmpty, t)
  4640  	}
  4641  	b := s.entryBlock()
  4642  	if t.ContainsSIMD() {
  4643  		// SIMD code needs to be guarded by feature checks, so
  4644  		// we can't put its zero value in the entry block.
  4645  		b = s.curBlock
  4646  	}
  4647  	switch {
  4648  	case t.IsInteger():
  4649  		switch t.Size() {
  4650  		case 1:
  4651  			return s.constInt8(t, 0)
  4652  		case 2:
  4653  			return s.constInt16(t, 0)
  4654  		case 4:
  4655  			return s.constInt32(t, 0)
  4656  		case 8:
  4657  			return s.constInt64(t, 0)
  4658  		default:
  4659  			s.Fatalf("bad sized integer type %v", t)
  4660  		}
  4661  	case t.IsFloat():
  4662  		switch t.Size() {
  4663  		case 4:
  4664  			return s.constFloat32(t, 0)
  4665  		case 8:
  4666  			return s.constFloat64(t, 0)
  4667  		default:
  4668  			s.Fatalf("bad sized float type %v", t)
  4669  		}
  4670  	case t.IsComplex():
  4671  		switch t.Size() {
  4672  		case 8:
  4673  			z := s.constFloat32(types.Types[types.TFLOAT32], 0)
  4674  			return s.entryNewValue2(ssaop.OpComplexMake, t, z, z)
  4675  		case 16:
  4676  			z := s.constFloat64(types.Types[types.TFLOAT64], 0)
  4677  			return s.entryNewValue2(ssaop.OpComplexMake, t, z, z)
  4678  		default:
  4679  			s.Fatalf("bad sized complex type %v", t)
  4680  		}
  4681  
  4682  	case t.IsString():
  4683  		return s.constEmptyString(t)
  4684  	case t.IsPtrShaped():
  4685  		return s.constNil(t)
  4686  	case t.IsBoolean():
  4687  		return s.constBool(false)
  4688  	case t.IsInterface():
  4689  		return s.constInterface(t)
  4690  	case t.IsSlice():
  4691  		return s.constSlice(t)
  4692  	case isStructNotSIMD(t):
  4693  		n := t.NumFields()
  4694  		v := b.NewValue0(src.NoXPos, ssaop.OpStructMake, t)
  4695  		for i := 0; i < n; i++ {
  4696  			v.AddArg(s.zeroVal(t.FieldType(i)))
  4697  		}
  4698  		return v
  4699  	case t.IsArray() && t.NumElem() == 1:
  4700  		return b.NewValue1(src.NoXPos, ssaop.OpArrayMake1, t, s.zeroVal(t.Elem()))
  4701  	case t.IsSIMD():
  4702  		return b.NewValue0(src.NoXPos, ssaop.OpZeroSIMD, t)
  4703  	}
  4704  	s.Fatalf("zero for type %v not implemented", t)
  4705  	return nil
  4706  }
  4707  
  4708  type callKind int8
  4709  
  4710  const (
  4711  	callNormal callKind = iota
  4712  	callDefer
  4713  	callDeferStack
  4714  	callGo
  4715  	callTail
  4716  )
  4717  
  4718  type sfRtCallDef struct {
  4719  	rtfn  *obj.LSym
  4720  	rtype types.Kind
  4721  }
  4722  
  4723  var softFloatOps map[ssaop.Op]sfRtCallDef
  4724  
  4725  func softfloatInit() {
  4726  	// Some of these operations get transformed by sfcall.
  4727  	softFloatOps = map[ssaop.Op]sfRtCallDef{
  4728  		ssaop.OpAdd32F: {typecheck.LookupRuntimeFunc("fadd32"), types.TFLOAT32},
  4729  		ssaop.OpAdd64F: {typecheck.LookupRuntimeFunc("fadd64"), types.TFLOAT64},
  4730  		ssaop.OpSub32F: {typecheck.LookupRuntimeFunc("fadd32"), types.TFLOAT32},
  4731  		ssaop.OpSub64F: {typecheck.LookupRuntimeFunc("fadd64"), types.TFLOAT64},
  4732  		ssaop.OpMul32F: {typecheck.LookupRuntimeFunc("fmul32"), types.TFLOAT32},
  4733  		ssaop.OpMul64F: {typecheck.LookupRuntimeFunc("fmul64"), types.TFLOAT64},
  4734  		ssaop.OpDiv32F: {typecheck.LookupRuntimeFunc("fdiv32"), types.TFLOAT32},
  4735  		ssaop.OpDiv64F: {typecheck.LookupRuntimeFunc("fdiv64"), types.TFLOAT64},
  4736  
  4737  		ssaop.OpEq64F:   {typecheck.LookupRuntimeFunc("feq64"), types.TBOOL},
  4738  		ssaop.OpEq32F:   {typecheck.LookupRuntimeFunc("feq32"), types.TBOOL},
  4739  		ssaop.OpNeq64F:  {typecheck.LookupRuntimeFunc("feq64"), types.TBOOL},
  4740  		ssaop.OpNeq32F:  {typecheck.LookupRuntimeFunc("feq32"), types.TBOOL},
  4741  		ssaop.OpLess64F: {typecheck.LookupRuntimeFunc("fgt64"), types.TBOOL},
  4742  		ssaop.OpLess32F: {typecheck.LookupRuntimeFunc("fgt32"), types.TBOOL},
  4743  		ssaop.OpLeq64F:  {typecheck.LookupRuntimeFunc("fge64"), types.TBOOL},
  4744  		ssaop.OpLeq32F:  {typecheck.LookupRuntimeFunc("fge32"), types.TBOOL},
  4745  
  4746  		ssaop.OpCvt32to32F:  {typecheck.LookupRuntimeFunc("fint32to32"), types.TFLOAT32},
  4747  		ssaop.OpCvt32Fto32:  {typecheck.LookupRuntimeFunc("f32toint32"), types.TINT32},
  4748  		ssaop.OpCvt64to32F:  {typecheck.LookupRuntimeFunc("fint64to32"), types.TFLOAT32},
  4749  		ssaop.OpCvt32Fto64:  {typecheck.LookupRuntimeFunc("f32toint64"), types.TINT64},
  4750  		ssaop.OpCvt64Uto32F: {typecheck.LookupRuntimeFunc("fuint64to32"), types.TFLOAT32},
  4751  		ssaop.OpCvt32Fto64U: {typecheck.LookupRuntimeFunc("f32touint64"), types.TUINT64},
  4752  		ssaop.OpCvt32to64F:  {typecheck.LookupRuntimeFunc("fint32to64"), types.TFLOAT64},
  4753  		ssaop.OpCvt64Fto32:  {typecheck.LookupRuntimeFunc("f64toint32"), types.TINT32},
  4754  		ssaop.OpCvt64to64F:  {typecheck.LookupRuntimeFunc("fint64to64"), types.TFLOAT64},
  4755  		ssaop.OpCvt64Fto64:  {typecheck.LookupRuntimeFunc("f64toint64"), types.TINT64},
  4756  		ssaop.OpCvt64Uto64F: {typecheck.LookupRuntimeFunc("fuint64to64"), types.TFLOAT64},
  4757  		ssaop.OpCvt64Fto64U: {typecheck.LookupRuntimeFunc("f64touint64"), types.TUINT64},
  4758  		ssaop.OpCvt32Fto64F: {typecheck.LookupRuntimeFunc("f32to64"), types.TFLOAT64},
  4759  		ssaop.OpCvt64Fto32F: {typecheck.LookupRuntimeFunc("f64to32"), types.TFLOAT32},
  4760  	}
  4761  }
  4762  
  4763  // TODO: do not emit sfcall if operation can be optimized to constant in later
  4764  // opt phase
  4765  func (s *state) sfcall(op ssaop.Op, args ...*ssa.Value) (*ssa.Value, bool) {
  4766  	f2i := func(t *types.Type) *types.Type {
  4767  		switch t.Kind() {
  4768  		case types.TFLOAT32:
  4769  			return types.Types[types.TUINT32]
  4770  		case types.TFLOAT64:
  4771  			return types.Types[types.TUINT64]
  4772  		}
  4773  		return t
  4774  	}
  4775  
  4776  	if callDef, ok := softFloatOps[op]; ok {
  4777  		switch op {
  4778  		case ssaop.OpLess32F,
  4779  			ssaop.OpLess64F,
  4780  			ssaop.OpLeq32F,
  4781  			ssaop.OpLeq64F:
  4782  			args[0], args[1] = args[1], args[0]
  4783  		case ssaop.OpSub32F,
  4784  			ssaop.OpSub64F:
  4785  			args[1] = s.newValue1(s.ssaOp(ir.ONEG, types.Types[callDef.rtype]), args[1].Type, args[1])
  4786  		}
  4787  
  4788  		// runtime functions take uints for floats and returns uints.
  4789  		// Convert to uints so we use the right calling convention.
  4790  		for i, a := range args {
  4791  			if a.Type.IsFloat() {
  4792  				args[i] = s.newValue1(ssaop.OpCopy, f2i(a.Type), a)
  4793  			}
  4794  		}
  4795  
  4796  		rt := types.Types[callDef.rtype]
  4797  		result := s.rtcall(callDef.rtfn, true, []*types.Type{f2i(rt)}, args...)[0]
  4798  		if rt.IsFloat() {
  4799  			result = s.newValue1(ssaop.OpCopy, rt, result)
  4800  		}
  4801  		if op == ssaop.OpNeq32F || op == ssaop.OpNeq64F {
  4802  			result = s.newValue1(ssaop.OpNot, result.Type, result)
  4803  		}
  4804  		return result, true
  4805  	}
  4806  	return nil, false
  4807  }
  4808  
  4809  // split breaks up a tuple-typed value into its 2 parts.
  4810  func (s *state) split(v *ssa.Value) (*ssa.Value, *ssa.Value) {
  4811  	p0 := s.newValue1(ssaop.OpSelect0, v.Type.FieldType(0), v)
  4812  	p1 := s.newValue1(ssaop.OpSelect1, v.Type.FieldType(1), v)
  4813  	return p0, p1
  4814  }
  4815  
  4816  // intrinsicCall converts a call to a recognized intrinsic function into the intrinsic SSA operation.
  4817  func (s *state) intrinsicCall(n *ir.CallExpr) *ssa.Value {
  4818  	v := findIntrinsic(n.Fun.Sym())(s, n, s.intrinsicArgs(n))
  4819  	if ssaconfig.IntrinsicsDebug > 0 {
  4820  		x := v
  4821  		if x == nil {
  4822  			x = s.mem()
  4823  		}
  4824  		if x.Op == ssaop.OpSelect0 || x.Op == ssaop.OpSelect1 {
  4825  			x = x.Args[0]
  4826  		}
  4827  		base.WarnfAt(n.Pos(), "intrinsic substitution for %v with %s", n.Fun.Sym().Name, x.LongString())
  4828  	}
  4829  	return v
  4830  }
  4831  
  4832  // intrinsicArgs extracts args from n, evaluates them to SSA values, and returns them.
  4833  func (s *state) intrinsicArgs(n *ir.CallExpr) []*ssa.Value {
  4834  	args := make([]*ssa.Value, len(n.Args))
  4835  	for i, n := range n.Args {
  4836  		args[i] = s.expr(n)
  4837  	}
  4838  	return args
  4839  }
  4840  
  4841  // openDeferRecord adds code to evaluate and store the function for an open-code defer
  4842  // call, and records info about the defer, so we can generate proper code on the
  4843  // exit paths. n is the sub-node of the defer node that is the actual function
  4844  // call. We will also record funcdata information on where the function is stored
  4845  // (as well as the deferBits variable), and this will enable us to run the proper
  4846  // defer calls during panics.
  4847  func (s *state) openDeferRecord(n *ir.CallExpr) {
  4848  	if len(n.Args) != 0 || n.Op() != ir.OCALLFUNC || n.Fun.Type().NumResults() != 0 {
  4849  		s.Fatalf("defer call with arguments or results: %v", n)
  4850  	}
  4851  
  4852  	opendefer := &openDeferInfo{
  4853  		n: n,
  4854  	}
  4855  	fn := n.Fun
  4856  	// We must always store the function value in a stack slot for the
  4857  	// runtime panic code to use. But in the defer exit code, we will
  4858  	// call the function directly if it is a static function.
  4859  	closureVal := s.expr(fn)
  4860  	closure := s.openDeferSave(fn.Type(), closureVal)
  4861  	opendefer.closureNode = closure.Aux.(*ir.Name)
  4862  	if !(fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC) {
  4863  		opendefer.closure = closure
  4864  	}
  4865  	index := len(s.openDefers)
  4866  	s.openDefers = append(s.openDefers, opendefer)
  4867  
  4868  	// Update deferBits only after evaluation and storage to stack of
  4869  	// the function is successful.
  4870  	bitvalue := s.constInt8(types.Types[types.TUINT8], 1<<uint(index))
  4871  	newDeferBits := s.newValue2(ssaop.OpOr8, types.Types[types.TUINT8], s.variable(deferBitsVar, types.Types[types.TUINT8]), bitvalue)
  4872  	s.vars[deferBitsVar] = newDeferBits
  4873  	s.store(types.Types[types.TUINT8], s.deferBitsAddr, newDeferBits)
  4874  }
  4875  
  4876  // openDeferSave generates SSA nodes to store a value (with type t) for an
  4877  // open-coded defer at an explicit autotmp location on the stack, so it can be
  4878  // reloaded and used for the appropriate call on exit. Type t must be a function type
  4879  // (therefore SSAable). val is the value to be stored. The function returns an SSA
  4880  // value representing a pointer to the autotmp location.
  4881  func (s *state) openDeferSave(t *types.Type, val *ssa.Value) *ssa.Value {
  4882  	if !ssa.CanSSA(t) {
  4883  		s.Fatalf("openDeferSave of non-SSA-able type %v val=%v", t, val)
  4884  	}
  4885  	if !t.HasPointers() {
  4886  		s.Fatalf("openDeferSave of pointerless type %v val=%v", t, val)
  4887  	}
  4888  	pos := val.Pos
  4889  	temp := typecheck.TempAt(pos.WithNotStmt(), s.curfn, t)
  4890  	temp.SetOpenDeferSlot(true)
  4891  	temp.SetFrameOffset(int64(len(s.openDefers))) // so cmpstackvarlt can order them
  4892  	var addrTemp *ssa.Value
  4893  	// Use OpVarLive to make sure stack slot for the closure is not removed by
  4894  	// dead-store elimination
  4895  	if s.curBlock.ID != s.f.Entry.ID {
  4896  		// Force the tmp storing this defer function to be declared in the entry
  4897  		// block, so that it will be live for the defer exit code (which will
  4898  		// actually access it only if the associated defer call has been activated).
  4899  		if t.HasPointers() {
  4900  			s.defvars[s.f.Entry.ID][memVar] = s.f.Entry.NewValue1A(src.NoXPos, ssaop.OpVarDef, types.TypeMem, temp, s.defvars[s.f.Entry.ID][memVar])
  4901  		}
  4902  		s.defvars[s.f.Entry.ID][memVar] = s.f.Entry.NewValue1A(src.NoXPos, ssaop.OpVarLive, types.TypeMem, temp, s.defvars[s.f.Entry.ID][memVar])
  4903  		addrTemp = s.f.Entry.NewValue2A(src.NoXPos, ssaop.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.defvars[s.f.Entry.ID][memVar])
  4904  	} else {
  4905  		// Special case if we're still in the entry block. We can't use
  4906  		// the above code, since s.defvars[s.f.Entry.ID] isn't defined
  4907  		// until we end the entry block with s.endBlock().
  4908  		if t.HasPointers() {
  4909  			s.vars[memVar] = s.newValue1Apos(ssaop.OpVarDef, types.TypeMem, temp, s.mem(), false)
  4910  		}
  4911  		s.vars[memVar] = s.newValue1Apos(ssaop.OpVarLive, types.TypeMem, temp, s.mem(), false)
  4912  		addrTemp = s.newValue2Apos(ssaop.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.mem(), false)
  4913  	}
  4914  	// Since we may use this temp during exit depending on the
  4915  	// deferBits, we must define it unconditionally on entry.
  4916  	// Therefore, we must make sure it is zeroed out in the entry
  4917  	// block if it contains pointers, else GC may wrongly follow an
  4918  	// uninitialized pointer value.
  4919  	temp.SetNeedzero(true)
  4920  	// We are storing to the stack, hence we can avoid the full checks in
  4921  	// storeType() (no write barrier) and do a simple store().
  4922  	s.store(t, addrTemp, val)
  4923  	return addrTemp
  4924  }
  4925  
  4926  // openDeferExit generates SSA for processing all the open coded defers at exit.
  4927  // The code involves loading deferBits, and checking each of the bits to see if
  4928  // the corresponding defer statement was executed. For each bit that is turned
  4929  // on, the associated defer call is made.
  4930  func (s *state) openDeferExit() {
  4931  	deferExit := s.f.NewBlock(block.BlockPlain)
  4932  	s.endBlock().AddEdgeTo(deferExit)
  4933  	s.startBlock(deferExit)
  4934  	s.lastDeferExit = deferExit
  4935  	s.lastDeferCount = len(s.openDefers)
  4936  	zeroval := s.constInt8(types.Types[types.TUINT8], 0)
  4937  	// Test for and run defers in reverse order
  4938  	for i := len(s.openDefers) - 1; i >= 0; i-- {
  4939  		r := s.openDefers[i]
  4940  		bCond := s.f.NewBlock(block.BlockPlain)
  4941  		bEnd := s.f.NewBlock(block.BlockPlain)
  4942  
  4943  		deferBits := s.variable(deferBitsVar, types.Types[types.TUINT8])
  4944  		// Generate code to check if the bit associated with the current
  4945  		// defer is set.
  4946  		bitval := s.constInt8(types.Types[types.TUINT8], 1<<uint(i))
  4947  		andval := s.newValue2(ssaop.OpAnd8, types.Types[types.TUINT8], deferBits, bitval)
  4948  		eqVal := s.newValue2(ssaop.OpEq8, types.Types[types.TBOOL], andval, zeroval)
  4949  		b := s.endBlock()
  4950  		b.Kind = block.BlockIf
  4951  		b.SetControl(eqVal)
  4952  		b.AddEdgeTo(bEnd)
  4953  		b.AddEdgeTo(bCond)
  4954  		bCond.AddEdgeTo(bEnd)
  4955  		s.startBlock(bCond)
  4956  
  4957  		// Clear this bit in deferBits and force store back to stack, so
  4958  		// we will not try to re-run this defer call if this defer call panics.
  4959  		nbitval := s.newValue1(ssaop.OpCom8, types.Types[types.TUINT8], bitval)
  4960  		maskedval := s.newValue2(ssaop.OpAnd8, types.Types[types.TUINT8], deferBits, nbitval)
  4961  		s.store(types.Types[types.TUINT8], s.deferBitsAddr, maskedval)
  4962  		// Use this value for following tests, so we keep previous
  4963  		// bits cleared.
  4964  		s.vars[deferBitsVar] = maskedval
  4965  
  4966  		// Generate code to call the function call of the defer, using the
  4967  		// closure that were stored in argtmps at the point of the defer
  4968  		// statement.
  4969  		fn := r.n.Fun
  4970  		stksize := fn.Type().ArgWidth()
  4971  		var callArgs []*ssa.Value
  4972  		var call *ssa.Value
  4973  		if r.closure != nil {
  4974  			v := s.load(r.closure.Type.Elem(), r.closure)
  4975  			s.maybeNilCheckClosure(v, callDefer)
  4976  			codeptr := s.rawLoad(types.Types[types.TUINTPTR], v)
  4977  			aux := ssa.ClosureAuxCall(s.f.ABIDefault.ABIAnalyzeTypes(nil, nil))
  4978  			call = s.newValue2A(ssaop.OpClosureLECall, aux.LateExpansionResultType(), aux, codeptr, v)
  4979  		} else {
  4980  			aux := ssa.StaticAuxCall(fn.(*ir.Name).Linksym(), s.f.ABIDefault.ABIAnalyzeTypes(nil, nil))
  4981  			call = s.newValue0A(ssaop.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4982  		}
  4983  		callArgs = append(callArgs, s.mem())
  4984  		call.AddArgs(callArgs...)
  4985  		call.AuxInt = stksize
  4986  		s.vars[memVar] = s.newValue1I(ssaop.OpSelectN, types.TypeMem, 0, call)
  4987  		// Make sure that the stack slots with pointers are kept live
  4988  		// through the call (which is a pre-emption point). Also, we will
  4989  		// use the first call of the last defer exit to compute liveness
  4990  		// for the deferreturn, so we want all stack slots to be live.
  4991  		if r.closureNode != nil {
  4992  			s.vars[memVar] = s.newValue1Apos(ssaop.OpVarLive, types.TypeMem, r.closureNode, s.mem(), false)
  4993  		}
  4994  
  4995  		s.endBlock()
  4996  		s.startBlock(bEnd)
  4997  	}
  4998  }
  4999  
  5000  func (s *state) callResult(n *ir.CallExpr, k callKind) *ssa.Value {
  5001  	return s.call(n, k, false, nil)
  5002  }
  5003  
  5004  func (s *state) callAddr(n *ir.CallExpr, k callKind) *ssa.Value {
  5005  	return s.call(n, k, true, nil)
  5006  }
  5007  
  5008  // Calls the function n using the specified call type.
  5009  // Returns the address of the return value (or nil if none).
  5010  func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool, deferExtra ir.Expr) *ssa.Value {
  5011  	s.prevCall = nil
  5012  	var calleeLSym *obj.LSym // target function (if static)
  5013  	var closure *ssa.Value   // ptr to closure to run (if dynamic)
  5014  	var codeptr *ssa.Value   // ptr to target code (if dynamic)
  5015  	var dextra *ssa.Value    // defer extra arg
  5016  	var rcvr *ssa.Value      // receiver to set
  5017  	fn := n.Fun
  5018  	var ACArgs []*types.Type    // AuxCall args
  5019  	var ACResults []*types.Type // AuxCall results
  5020  	var callArgs []*ssa.Value   // For late-expansion, the args themselves (not stored, args to the call instead).
  5021  
  5022  	callABI := s.f.ABIDefault
  5023  
  5024  	if k != callNormal && k != callTail && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.Fun.Type().NumResults() != 0) {
  5025  		s.Fatalf("go/defer call with arguments: %v", n)
  5026  	}
  5027  
  5028  	isCallDeferRangeFunc := false
  5029  
  5030  	switch n.Op() {
  5031  	case ir.OCALLFUNC:
  5032  		if (k == callNormal || k == callTail) && fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC {
  5033  			fn := fn.(*ir.Name)
  5034  			calleeLSym = callTargetLSym(fn)
  5035  			if buildcfg.Experiment.RegabiArgs {
  5036  				// This is a static call, so it may be
  5037  				// a direct call to a non-ABIInternal
  5038  				// function. fn.Func may be nil for
  5039  				// some compiler-generated functions,
  5040  				// but those are all ABIInternal.
  5041  				if fn.Func != nil {
  5042  					callABI = abiForFunc(fn.Func, s.f.ABI0, s.f.ABI1)
  5043  				}
  5044  			} else {
  5045  				// TODO(register args) remove after register abi is working
  5046  				inRegistersImported := fn.Pragma()&ir.RegisterParams != 0
  5047  				inRegistersSamePackage := fn.Func != nil && fn.Func.Pragma&ir.RegisterParams != 0
  5048  				if inRegistersImported || inRegistersSamePackage {
  5049  					callABI = s.f.ABI1
  5050  				}
  5051  			}
  5052  			if fn := n.Fun.Sym().Name; n.Fun.Sym().Pkg == ir.Pkgs.Runtime && fn == "deferrangefunc" {
  5053  				isCallDeferRangeFunc = true
  5054  			}
  5055  			break
  5056  		}
  5057  		closure = s.expr(fn)
  5058  		if k != callDefer && k != callDeferStack {
  5059  			// Deferred nil function needs to panic when the function is invoked,
  5060  			// not the point of defer statement.
  5061  			s.maybeNilCheckClosure(closure, k)
  5062  		}
  5063  	case ir.OCALLINTER:
  5064  		if fn.Op() != ir.ODOTINTER {
  5065  			s.Fatalf("OCALLINTER: n.Left not an ODOTINTER: %v", fn.Op())
  5066  		}
  5067  		fn := fn.(*ir.SelectorExpr)
  5068  		var iclosure *ssa.Value
  5069  		iclosure, rcvr = s.getClosureAndRcvr(fn)
  5070  		if k == callNormal || k == callTail {
  5071  			codeptr = s.load(types.Types[types.TUINTPTR], iclosure)
  5072  		} else {
  5073  			closure = iclosure
  5074  		}
  5075  	}
  5076  	if deferExtra != nil {
  5077  		dextra = s.expr(deferExtra)
  5078  	}
  5079  
  5080  	params := callABI.ABIAnalyze(n.Fun.Type(), false /* Do not set (register) nNames from caller side -- can cause races. */)
  5081  	types.CalcSize(fn.Type())
  5082  	stksize := params.ArgWidth() // includes receiver, args, and results
  5083  
  5084  	res := n.Fun.Type().Results()
  5085  	if k == callNormal || k == callTail {
  5086  		for _, p := range params.OutParams() {
  5087  			ACResults = append(ACResults, p.Type)
  5088  		}
  5089  	}
  5090  
  5091  	var call *ssa.Value
  5092  	if k == callDeferStack {
  5093  		if stksize != 0 {
  5094  			s.Fatalf("deferprocStack with non-zero stack size %d: %v", stksize, n)
  5095  		}
  5096  		// Make a defer struct on the stack.
  5097  		t := deferstruct()
  5098  		n, addr := s.temp(n.Pos(), t)
  5099  		n.SetNonMergeable(true)
  5100  		s.store(closure.Type,
  5101  			s.newValue1I(ssaop.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(deferStructFnField), addr),
  5102  			closure)
  5103  
  5104  		// Call runtime.deferprocStack with pointer to _defer record.
  5105  		ACArgs = append(ACArgs, types.Types[types.TUINTPTR])
  5106  		aux := ssa.StaticAuxCall(ir.Syms.DeferprocStack, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults))
  5107  		callArgs = append(callArgs, addr, s.mem())
  5108  		call = s.newValue0A(ssaop.OpStaticLECall, aux.LateExpansionResultType(), aux)
  5109  		call.AddArgs(callArgs...)
  5110  		call.AuxInt = int64(types.PtrSize) // deferprocStack takes a *_defer arg
  5111  	} else {
  5112  		// Store arguments to stack, including defer/go arguments and receiver for method calls.
  5113  		// These are written in SP-offset order.
  5114  		argStart := base.Ctxt.Arch.FixedFrameSize
  5115  		// Defer/go args.
  5116  		if k != callNormal && k != callTail {
  5117  			// Write closure (arg to newproc/deferproc).
  5118  			ACArgs = append(ACArgs, types.Types[types.TUINTPTR]) // not argExtra
  5119  			callArgs = append(callArgs, closure)
  5120  			stksize += int64(types.PtrSize)
  5121  			argStart += int64(types.PtrSize)
  5122  			if dextra != nil {
  5123  				// Extra token of type any for deferproc
  5124  				ACArgs = append(ACArgs, types.Types[types.TINTER])
  5125  				callArgs = append(callArgs, dextra)
  5126  				stksize += 2 * int64(types.PtrSize)
  5127  				argStart += 2 * int64(types.PtrSize)
  5128  			}
  5129  		}
  5130  
  5131  		// Set receiver (for interface calls).
  5132  		if rcvr != nil {
  5133  			callArgs = append(callArgs, rcvr)
  5134  		}
  5135  
  5136  		// Write args.
  5137  		t := n.Fun.Type()
  5138  		args := n.Args
  5139  
  5140  		for _, p := range params.InParams() { // includes receiver for interface calls
  5141  			ACArgs = append(ACArgs, p.Type)
  5142  		}
  5143  
  5144  		// Split the entry block if there are open defers, because later calls to
  5145  		// openDeferSave may cause a mismatch between the mem for an OpDereference
  5146  		// and the call site which uses it. See #49282.
  5147  		if s.curBlock.ID == s.f.Entry.ID && s.hasOpenDefers {
  5148  			b := s.endBlock()
  5149  			b.Kind = block.BlockPlain
  5150  			curb := s.f.NewBlock(block.BlockPlain)
  5151  			b.AddEdgeTo(curb)
  5152  			s.startBlock(curb)
  5153  		}
  5154  
  5155  		for i, n := range args {
  5156  			callArgs = append(callArgs, s.putArg(n, t.Param(i).Type))
  5157  		}
  5158  
  5159  		// In -race mode, we need to call racefuncexit before a tail call.
  5160  		// A tail call reuses our frame and returns directly to our caller,
  5161  		// so this is the last chance we get to tell the race detector that
  5162  		// this function is done. Note: this has to happen after the
  5163  		// arguments are evaluated, otherwise races in the argument
  5164  		// expressions would be attributed to the caller instead.
  5165  		if k == callTail && s.instrumentEnterExit {
  5166  			s.rtcall(ir.Syms.Racefuncexit, true, nil)
  5167  		}
  5168  
  5169  		callArgs = append(callArgs, s.mem())
  5170  
  5171  		// call target
  5172  		switch {
  5173  		case k == callDefer:
  5174  			sym := ir.Syms.Deferproc
  5175  			if dextra != nil {
  5176  				sym = ir.Syms.Deferprocat
  5177  			}
  5178  			aux := ssa.StaticAuxCall(sym, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults)) // TODO paramResultInfo for Deferproc(at)
  5179  			call = s.newValue0A(ssaop.OpStaticLECall, aux.LateExpansionResultType(), aux)
  5180  		case k == callGo:
  5181  			aux := ssa.StaticAuxCall(ir.Syms.Newproc, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults))
  5182  			call = s.newValue0A(ssaop.OpStaticLECall, aux.LateExpansionResultType(), aux) // TODO paramResultInfo for Newproc
  5183  		case closure != nil:
  5184  			// rawLoad because loading the code pointer from a
  5185  			// closure is always safe, but IsSanitizerSafeAddr
  5186  			// can't always figure that out currently, and it's
  5187  			// critical that we not clobber any arguments already
  5188  			// stored onto the stack.
  5189  			codeptr = s.rawLoad(types.Types[types.TUINTPTR], closure)
  5190  			aux := ssa.ClosureAuxCall(callABI.ABIAnalyzeTypes(ACArgs, ACResults))
  5191  			call = s.newValue2A(ssaop.OpClosureLECall, aux.LateExpansionResultType(), aux, codeptr, closure)
  5192  		case codeptr != nil:
  5193  			// Note that the "receiver" parameter is nil because the actual receiver is the first input parameter.
  5194  			aux := ssa.InterfaceAuxCall(params)
  5195  			call = s.newValue1A(ssaop.OpInterLECall, aux.LateExpansionResultType(), aux, codeptr)
  5196  			if k == callTail {
  5197  				call.Op = ssaop.OpTailLECallInter
  5198  				stksize = 0 // Tail call does not use stack. We reuse caller's frame.
  5199  			}
  5200  		case calleeLSym != nil:
  5201  			aux := ssa.StaticAuxCall(calleeLSym, params)
  5202  			call = s.newValue0A(ssaop.OpStaticLECall, aux.LateExpansionResultType(), aux)
  5203  			if k == callTail {
  5204  				call.Op = ssaop.OpTailLECall
  5205  				stksize = 0 // Tail call does not use stack. We reuse caller's frame.
  5206  			}
  5207  		default:
  5208  			s.Fatalf("bad call type %v %v", n.Op(), n)
  5209  		}
  5210  		call.AddArgs(callArgs...)
  5211  		call.AuxInt = stksize // Call operations carry the argsize of the callee along with them
  5212  	}
  5213  	s.prevCall = call
  5214  	s.vars[memVar] = s.newValue1I(ssaop.OpSelectN, types.TypeMem, int64(len(ACResults)), call)
  5215  	// Insert VarLive opcodes.
  5216  	for _, v := range n.KeepAlive {
  5217  		if !v.Addrtaken() {
  5218  			s.Fatalf("KeepAlive variable %v must have Addrtaken set", v)
  5219  		}
  5220  		switch v.Class {
  5221  		case ir.PAUTO, ir.PPARAM, ir.PPARAMOUT:
  5222  		default:
  5223  			s.Fatalf("KeepAlive variable %v must be Auto or Arg", v)
  5224  		}
  5225  		s.vars[memVar] = s.newValue1A(ssaop.OpVarLive, types.TypeMem, v, s.mem())
  5226  	}
  5227  
  5228  	// Build result value (before we might end the defer block, below).
  5229  	var result *ssa.Value
  5230  	if len(res) == 0 || k != callNormal {
  5231  		result = nil
  5232  	} else {
  5233  		fp := res[0]
  5234  		if returnResultAddr {
  5235  			result = s.resultAddrOfCall(call, 0, fp.Type)
  5236  		} else {
  5237  			result = s.newValue1I(ssaop.OpSelectN, fp.Type, 0, call)
  5238  		}
  5239  		if n.Reshape {
  5240  			result = s.newValue1(ssaop.OpCopy, n.Type(), result)
  5241  		}
  5242  	}
  5243  
  5244  	// Finish block for defers
  5245  	if k == callDefer || k == callDeferStack || isCallDeferRangeFunc {
  5246  		b := s.endBlock()
  5247  		b.Kind = block.BlockDefer
  5248  		b.SetControl(call)
  5249  		bNext := s.f.NewBlock(block.BlockPlain)
  5250  		b.AddEdgeTo(bNext)
  5251  		r := s.f.DeferReturn // Share a single deferreturn among all defers
  5252  		if r == nil {
  5253  			r = s.f.NewBlock(block.BlockPlain)
  5254  			s.startBlock(r)
  5255  			s.exit()
  5256  			s.f.DeferReturn = r
  5257  		}
  5258  		b.AddEdgeTo(r) // Add recover edge to exit code.  This is a fake edge to keep the block live.
  5259  		b.Likely = ssa.BranchLikely
  5260  		s.startBlock(bNext)
  5261  	}
  5262  
  5263  	return result
  5264  }
  5265  
  5266  // maybeNilCheckClosure checks if a nil check of a closure is needed in some
  5267  // architecture-dependent situations and, if so, emits the nil check.
  5268  func (s *state) maybeNilCheckClosure(closure *ssa.Value, k callKind) {
  5269  	if Arch.LinkArch.Family == sys.Wasm || buildcfg.GOOS == "aix" && k != callGo {
  5270  		// On AIX, the closure needs to be verified as fn can be nil, except if it's a call go. This needs to be handled by the runtime to have the "go of nil func value" error.
  5271  		// TODO(neelance): On other architectures this should be eliminated by the optimization steps
  5272  		s.nilCheck(closure)
  5273  	}
  5274  }
  5275  
  5276  // getClosureAndRcvr returns values for the appropriate closure and receiver of an
  5277  // interface call
  5278  func (s *state) getClosureAndRcvr(fn *ir.SelectorExpr) (*ssa.Value, *ssa.Value) {
  5279  	i := s.expr(fn.X)
  5280  	itab := s.newValue1(ssaop.OpITab, types.Types[types.TUINTPTR], i)
  5281  	s.nilCheck(itab)
  5282  	itabidx := fn.Offset() + rttype.ITab.OffsetOf("Fun")
  5283  	closure := s.newValue1I(ssaop.OpOffPtr, s.f.Config.Types.UintptrPtr, itabidx, itab)
  5284  	rcvr := s.newValue1(ssaop.OpIData, s.f.Config.Types.BytePtr, i)
  5285  	return closure, rcvr
  5286  }
  5287  
  5288  // etypesign returns the signed-ness of e, for integer/pointer etypes.
  5289  // -1 means signed, +1 means unsigned, 0 means non-integer/non-pointer.
  5290  func etypesign(e types.Kind) int8 {
  5291  	switch e {
  5292  	case types.TINT8, types.TINT16, types.TINT32, types.TINT64, types.TINT:
  5293  		return -1
  5294  	case types.TUINT8, types.TUINT16, types.TUINT32, types.TUINT64, types.TUINT, types.TUINTPTR, types.TUNSAFEPTR:
  5295  		return +1
  5296  	}
  5297  	return 0
  5298  }
  5299  
  5300  // addr converts the address of the expression n to SSA, adds it to s and returns the SSA result.
  5301  // The value that the returned Value represents is guaranteed to be non-nil.
  5302  func (s *state) addr(n ir.Node) *ssa.Value {
  5303  	if n.Op() != ir.ONAME {
  5304  		s.pushLine(n.Pos())
  5305  		defer s.popLine()
  5306  	}
  5307  
  5308  	if s.canSSA(n) {
  5309  		// This happens in weird, always-panics cases, like:
  5310  		//     var x [0][2]int
  5311  		//     x[i][j] = 5
  5312  		// The outer assignment, ...[j] = 5, is a fine
  5313  		// assignment to do, but requires computing the address
  5314  		// &x[i], which will always panic when evaluated.
  5315  		// We just return something reasonable in this case.
  5316  		// It will be dynamically unreachable. See issue 77635.
  5317  		s.boundsCheckArrayIndex(n)
  5318  		return s.newValue1A(ssaop.OpAddr, n.Type().PtrTo(), ir.Syms.Zerobase, s.sb)
  5319  	}
  5320  
  5321  	t := types.NewPtr(n.Type())
  5322  	linksymOffset := func(lsym *obj.LSym, offset int64) *ssa.Value {
  5323  		v := s.entryNewValue1A(ssaop.OpAddr, t, lsym, s.sb)
  5324  		// TODO: Make OpAddr use AuxInt as well as Aux.
  5325  		if offset != 0 {
  5326  			v = s.entryNewValue1I(ssaop.OpOffPtr, v.Type, offset, v)
  5327  		}
  5328  		return v
  5329  	}
  5330  	switch n.Op() {
  5331  	case ir.OLINKSYMOFFSET:
  5332  		no := n.(*ir.LinksymOffsetExpr)
  5333  		return linksymOffset(no.Linksym, no.Offset_)
  5334  	case ir.ONAME:
  5335  		n := n.(*ir.Name)
  5336  		if n.Heapaddr != nil {
  5337  			return s.expr(n.Heapaddr)
  5338  		}
  5339  		switch n.Class {
  5340  		case ir.PEXTERN:
  5341  			// global variable
  5342  			return linksymOffset(n.Linksym(), 0)
  5343  		case ir.PPARAM:
  5344  			// parameter slot
  5345  			v := s.decladdrs[n]
  5346  			if v != nil {
  5347  				return v
  5348  			}
  5349  			s.Fatalf("addr of undeclared ONAME %v. declared: %v", n, s.decladdrs)
  5350  			return nil
  5351  		case ir.PAUTO:
  5352  			return s.newValue2Apos(ssaop.OpLocalAddr, t, n, s.sp, s.mem(), !ir.IsAutoTmp(n))
  5353  
  5354  		case ir.PPARAMOUT: // Same as PAUTO -- cannot generate LEA early.
  5355  			// ensure that we reuse symbols for out parameters so
  5356  			// that cse works on their addresses
  5357  			return s.newValue2Apos(ssaop.OpLocalAddr, t, n, s.sp, s.mem(), true)
  5358  		default:
  5359  			s.Fatalf("variable address class %v not implemented", n.Class)
  5360  			return nil
  5361  		}
  5362  	case ir.ORESULT:
  5363  		// load return from callee
  5364  		n := n.(*ir.ResultExpr)
  5365  		return s.resultAddrOfCall(s.prevCall, n.Index, n.Type())
  5366  	case ir.OINDEX:
  5367  		n := n.(*ir.IndexExpr)
  5368  		if n.X.Type().IsSlice() {
  5369  			a := s.expr(n.X)
  5370  			i := s.expr(n.Index)
  5371  			len := s.newValue1(ssaop.OpSliceLen, types.Types[types.TINT], a)
  5372  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  5373  			p := s.newValue1(ssaop.OpSlicePtr, t, a)
  5374  			return s.newValue2(ssaop.OpPtrIndex, t, p, i)
  5375  		} else { // array
  5376  			a := s.addr(n.X)
  5377  			i := s.expr(n.Index)
  5378  			len := s.constInt(types.Types[types.TINT], n.X.Type().NumElem())
  5379  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  5380  			return s.newValue2(ssaop.OpPtrIndex, types.NewPtr(n.X.Type().Elem()), a, i)
  5381  		}
  5382  	case ir.ODEREF:
  5383  		n := n.(*ir.StarExpr)
  5384  		return s.exprPtr(n.X, n.Bounded(), n.Pos())
  5385  	case ir.ODOT:
  5386  		n := n.(*ir.SelectorExpr)
  5387  		p := s.addr(n.X)
  5388  		return s.newValue1I(ssaop.OpOffPtr, t, n.Offset(), p)
  5389  	case ir.ODOTPTR:
  5390  		n := n.(*ir.SelectorExpr)
  5391  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  5392  		return s.newValue1I(ssaop.OpOffPtr, t, n.Offset(), p)
  5393  	case ir.OCONVNOP:
  5394  		n := n.(*ir.ConvExpr)
  5395  		if n.Type() == n.X.Type() {
  5396  			return s.addr(n.X)
  5397  		}
  5398  		addr := s.addr(n.X)
  5399  		return s.newValue1(ssaop.OpCopy, t, addr) // ensure that addr has the right type
  5400  	case ir.OCALLFUNC, ir.OCALLINTER:
  5401  		n := n.(*ir.CallExpr)
  5402  		return s.callAddr(n, callNormal)
  5403  	case ir.ODOTTYPE, ir.ODYNAMICDOTTYPE:
  5404  		var v *ssa.Value
  5405  		if n.Op() == ir.ODOTTYPE {
  5406  			v, _ = s.dottype(n.(*ir.TypeAssertExpr), false)
  5407  		} else {
  5408  			v, _ = s.dynamicDottype(n.(*ir.DynamicTypeAssertExpr), false)
  5409  		}
  5410  		if v.Op != ssaop.OpLoad {
  5411  			s.Fatalf("dottype of non-load")
  5412  		}
  5413  		if v.Args[1] != s.mem() {
  5414  			s.Fatalf("memory no longer live from dottype load")
  5415  		}
  5416  		return v.Args[0]
  5417  	default:
  5418  		s.Fatalf("unhandled addr %v", n.Op())
  5419  		return nil
  5420  	}
  5421  }
  5422  
  5423  // canSSA reports whether n is SSA-able.
  5424  // n must be an ONAME (or an ODOT sequence with an ONAME base).
  5425  func (s *state) canSSA(n ir.Node) bool {
  5426  	if base.Flag.N != 0 {
  5427  		return false
  5428  	}
  5429  	for {
  5430  		nn := n
  5431  		if nn.Op() == ir.ODOT {
  5432  			nn := nn.(*ir.SelectorExpr)
  5433  			n = nn.X
  5434  			continue
  5435  		}
  5436  		if nn.Op() == ir.OINDEX {
  5437  			nn := nn.(*ir.IndexExpr)
  5438  			if nn.X.Type().IsArray() {
  5439  				n = nn.X
  5440  				continue
  5441  			}
  5442  		}
  5443  		break
  5444  	}
  5445  	if n.Op() != ir.ONAME {
  5446  		return false
  5447  	}
  5448  	return s.canSSAName(n.(*ir.Name)) && ssa.CanSSA(n.Type())
  5449  }
  5450  
  5451  func (s *state) canSSAName(name *ir.Name) bool {
  5452  	if name.Addrtaken() || !name.OnStack() {
  5453  		return false
  5454  	}
  5455  	switch name.Class {
  5456  	case ir.PPARAMOUT:
  5457  		if s.hasdefer {
  5458  			// TODO: handle this case? Named return values must be
  5459  			// in memory so that the deferred function can see them.
  5460  			// Maybe do: if !strings.HasPrefix(n.String(), "~") { return false }
  5461  			// Or maybe not, see issue 18860.  Even unnamed return values
  5462  			// must be written back so if a defer recovers, the caller can see them.
  5463  			return false
  5464  		}
  5465  		if s.cgoUnsafeArgs {
  5466  			// Cgo effectively takes the address of all result args,
  5467  			// but the compiler can't see that.
  5468  			return false
  5469  		}
  5470  	}
  5471  	return true
  5472  	// TODO: try to make more variables SSAable?
  5473  }
  5474  
  5475  // exprPtr evaluates n to a pointer and nil-checks it.
  5476  func (s *state) exprPtr(n ir.Node, bounded bool, lineno src.XPos) *ssa.Value {
  5477  	p := s.expr(n)
  5478  	if bounded || n.NonNil() {
  5479  		if s.f.Frontend().Debug_checknil() && lineno.Line() > 1 {
  5480  			s.f.Warnl(lineno, "removed nil check")
  5481  		}
  5482  		return p
  5483  	}
  5484  	p = s.nilCheck(p)
  5485  	return p
  5486  }
  5487  
  5488  // nilCheck generates nil pointer checking code.
  5489  // Used only for automatically inserted nil checks,
  5490  // not for user code like 'x != nil'.
  5491  // Returns a "definitely not nil" copy of x to ensure proper ordering
  5492  // of the uses of the post-nilcheck pointer.
  5493  func (s *state) nilCheck(ptr *ssa.Value) *ssa.Value {
  5494  	if base.Debug.DisableNil != 0 || s.curfn.NilCheckDisabled() {
  5495  		return ptr
  5496  	}
  5497  	return s.newValue2(ssaop.OpNilCheck, ptr.Type, ptr, s.mem())
  5498  }
  5499  
  5500  // boundsCheckArrayIndex generates bounds checking code for array indexing operations.
  5501  func (s *state) boundsCheckArrayIndex(n ir.Node) {
  5502  	if n.Op() != ir.OINDEX {
  5503  		return
  5504  	}
  5505  	nn := n.(*ir.IndexExpr)
  5506  	typ := nn.X.Type()
  5507  	if typ.IsArray() {
  5508  		_ = s.expr(nn.X) // for side effects
  5509  		idx := s.expr(nn.Index)
  5510  		len := s.constInt(types.Types[types.TINT], typ.NumElem())
  5511  		s.boundsCheck(idx, len, ssa.BoundsIndex, nn.Bounded())
  5512  	}
  5513  }
  5514  
  5515  // boundsCheck generates bounds checking code. Checks if 0 <= idx <[=] len, branches to exit if not.
  5516  // Starts a new block on return.
  5517  // On input, len must be converted to full int width and be nonnegative.
  5518  // Returns idx converted to full int width.
  5519  // If bounded is true then caller guarantees the index is not out of bounds
  5520  // (but boundsCheck will still extend the index to full int width).
  5521  func (s *state) boundsCheck(idx, len *ssa.Value, kind ssa.BoundsKind, bounded bool) *ssa.Value {
  5522  	idx = s.extendIndex(idx, len, kind, bounded)
  5523  
  5524  	if bounded || base.Flag.B != 0 {
  5525  		// If bounded or bounds checking is flag-disabled, then no check necessary,
  5526  		// just return the extended index.
  5527  		//
  5528  		// Here, bounded == true if the compiler generated the index itself,
  5529  		// such as in the expansion of a slice initializer. These indexes are
  5530  		// compiler-generated, not Go program variables, so they cannot be
  5531  		// attacker-controlled, so we can omit Spectre masking as well.
  5532  		//
  5533  		// Note that we do not want to omit Spectre masking in code like:
  5534  		//
  5535  		//	if 0 <= i && i < len(x) {
  5536  		//		use(x[i])
  5537  		//	}
  5538  		//
  5539  		// Lucky for us, bounded==false for that code.
  5540  		// In that case (handled below), we emit a bound check (and Spectre mask)
  5541  		// and then the prove pass will remove the bounds check.
  5542  		// In theory the prove pass could potentially remove certain
  5543  		// Spectre masks, but it's very delicate and probably better
  5544  		// to be conservative and leave them all in.
  5545  		return idx
  5546  	}
  5547  
  5548  	bNext := s.f.NewBlock(block.BlockPlain)
  5549  	bPanic := s.f.NewBlock(block.BlockExit)
  5550  
  5551  	if !idx.Type.IsSigned() {
  5552  		switch kind {
  5553  		case ssa.BoundsIndex:
  5554  			kind = ssa.BoundsIndexU
  5555  		case ssa.BoundsSliceAlen:
  5556  			kind = ssa.BoundsSliceAlenU
  5557  		case ssa.BoundsSliceAcap:
  5558  			kind = ssa.BoundsSliceAcapU
  5559  		case ssa.BoundsSliceB:
  5560  			kind = ssa.BoundsSliceBU
  5561  		case ssa.BoundsSlice3Alen:
  5562  			kind = ssa.BoundsSlice3AlenU
  5563  		case ssa.BoundsSlice3Acap:
  5564  			kind = ssa.BoundsSlice3AcapU
  5565  		case ssa.BoundsSlice3B:
  5566  			kind = ssa.BoundsSlice3BU
  5567  		case ssa.BoundsSlice3C:
  5568  			kind = ssa.BoundsSlice3CU
  5569  		}
  5570  	}
  5571  
  5572  	var cmp *ssa.Value
  5573  	if kind == ssa.BoundsIndex || kind == ssa.BoundsIndexU {
  5574  		cmp = s.newValue2(ssaop.OpIsInBounds, types.Types[types.TBOOL], idx, len)
  5575  	} else {
  5576  		cmp = s.newValue2(ssaop.OpIsSliceInBounds, types.Types[types.TBOOL], idx, len)
  5577  	}
  5578  	b := s.endBlock()
  5579  	b.Kind = block.BlockIf
  5580  	b.SetControl(cmp)
  5581  	b.Likely = ssa.BranchLikely
  5582  	b.AddEdgeTo(bNext)
  5583  	b.AddEdgeTo(bPanic)
  5584  
  5585  	s.startBlock(bPanic)
  5586  	if Arch.LinkArch.Family == sys.Wasm {
  5587  		// TODO(khr): figure out how to do "register" based calling convention for bounds checks.
  5588  		// Should be similar to gcWriteBarrier, but I can't make it work.
  5589  		s.rtcall(BoundsCheckFunc[kind], false, nil, idx, len)
  5590  	} else {
  5591  		mem := s.newValue3I(ssaop.OpPanicBounds, types.TypeMem, int64(kind), idx, len, s.mem())
  5592  		s.endBlock().SetControl(mem)
  5593  	}
  5594  	s.startBlock(bNext)
  5595  
  5596  	// In Spectre index mode, apply an appropriate mask to avoid speculative out-of-bounds accesses.
  5597  	if base.Flag.Cfg.SpectreIndex {
  5598  		op := ssaop.OpSpectreIndex
  5599  		if kind != ssa.BoundsIndex && kind != ssa.BoundsIndexU {
  5600  			op = ssaop.OpSpectreSliceIndex
  5601  		}
  5602  		idx = s.newValue2(op, types.Types[types.TINT], idx, len)
  5603  	}
  5604  
  5605  	return idx
  5606  }
  5607  
  5608  // If cmp (a bool) is false, panic using the given function.
  5609  func (s *state) check(cmp *ssa.Value, fn *obj.LSym) {
  5610  	b := s.endBlock()
  5611  	b.Kind = block.BlockIf
  5612  	b.SetControl(cmp)
  5613  	b.Likely = ssa.BranchLikely
  5614  	bNext := s.f.NewBlock(block.BlockPlain)
  5615  	line := s.peekPos()
  5616  	pos := base.Ctxt.PosTable.Pos(line)
  5617  	fl := funcLine{f: fn, base: pos.Base(), line: pos.Line()}
  5618  	bPanic := s.panics[fl]
  5619  	if bPanic == nil {
  5620  		bPanic = s.f.NewBlock(block.BlockPlain)
  5621  		s.panics[fl] = bPanic
  5622  		s.startBlock(bPanic)
  5623  		// The panic call takes/returns memory to ensure that the right
  5624  		// memory state is observed if the panic happens.
  5625  		s.rtcall(fn, false, nil)
  5626  	}
  5627  	b.AddEdgeTo(bNext)
  5628  	b.AddEdgeTo(bPanic)
  5629  	s.startBlock(bNext)
  5630  }
  5631  
  5632  func (s *state) intDivide(n ir.Node, a, b *ssa.Value) *ssa.Value {
  5633  	needcheck := true
  5634  	switch b.Op {
  5635  	case ssaop.OpConst8, ssaop.OpConst16, ssaop.OpConst32, ssaop.OpConst64:
  5636  		if b.AuxInt != 0 {
  5637  			needcheck = false
  5638  		}
  5639  	}
  5640  	if needcheck {
  5641  		// do a size-appropriate check for zero
  5642  		cmp := s.newValue2(s.ssaOp(ir.ONE, n.Type()), types.Types[types.TBOOL], b, s.zeroVal(n.Type()))
  5643  		s.check(cmp, ir.Syms.Panicdivide)
  5644  	}
  5645  	return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  5646  }
  5647  
  5648  // rtcall issues a call to the given runtime function fn with the listed args.
  5649  // Returns a slice of results of the given result types.
  5650  // The call is added to the end of the current block.
  5651  // If returns is false, the block is marked as an exit block.
  5652  func (s *state) rtcall(fn *obj.LSym, returns bool, results []*types.Type, args ...*ssa.Value) []*ssa.Value {
  5653  	s.prevCall = nil
  5654  	// Write args to the stack
  5655  	off := base.Ctxt.Arch.FixedFrameSize
  5656  	var callArgs []*ssa.Value
  5657  	var callArgTypes []*types.Type
  5658  
  5659  	for _, arg := range args {
  5660  		t := arg.Type
  5661  		off = types.RoundUp(off, t.Alignment())
  5662  		size := t.Size()
  5663  		callArgs = append(callArgs, arg)
  5664  		callArgTypes = append(callArgTypes, t)
  5665  		off += size
  5666  	}
  5667  	off = types.RoundUp(off, int64(types.RegSize))
  5668  
  5669  	// Issue call
  5670  	var call *ssa.Value
  5671  	aux := ssa.StaticAuxCall(fn, s.f.ABIDefault.ABIAnalyzeTypes(callArgTypes, results))
  5672  	callArgs = append(callArgs, s.mem())
  5673  	call = s.newValue0A(ssaop.OpStaticLECall, aux.LateExpansionResultType(), aux)
  5674  	call.AddArgs(callArgs...)
  5675  	s.vars[memVar] = s.newValue1I(ssaop.OpSelectN, types.TypeMem, int64(len(results)), call)
  5676  
  5677  	if !returns {
  5678  		// Finish block
  5679  		b := s.endBlock()
  5680  		b.Kind = block.BlockExit
  5681  		b.SetControl(call)
  5682  		call.AuxInt = off - base.Ctxt.Arch.FixedFrameSize
  5683  		if len(results) > 0 {
  5684  			s.Fatalf("panic call can't have results")
  5685  		}
  5686  		return nil
  5687  	}
  5688  
  5689  	// Load results
  5690  	res := make([]*ssa.Value, len(results))
  5691  	for i, t := range results {
  5692  		off = types.RoundUp(off, t.Alignment())
  5693  		res[i] = s.resultOfCall(call, int64(i), t)
  5694  		off += t.Size()
  5695  	}
  5696  	off = types.RoundUp(off, int64(types.PtrSize))
  5697  
  5698  	// Remember how much callee stack space we needed.
  5699  	call.AuxInt = off
  5700  
  5701  	return res
  5702  }
  5703  
  5704  // do *left = right for type t.
  5705  func (s *state) storeType(t *types.Type, left, right *ssa.Value, skip skipMask, leftIsStmt bool) {
  5706  	s.instrument(t, left, instrumentWrite)
  5707  
  5708  	if skip == 0 && (!t.HasPointers() || ssa.IsStackAddr(left)) {
  5709  		// Known to not have write barrier. Store the whole type.
  5710  		s.vars[memVar] = s.newValue3Apos(ssaop.OpStore, types.TypeMem, t, left, right, s.mem(), leftIsStmt)
  5711  		return
  5712  	}
  5713  
  5714  	// store scalar fields first, so write barrier stores for
  5715  	// pointer fields can be grouped together, and scalar values
  5716  	// don't need to be live across the write barrier call.
  5717  	// TODO: if the writebarrier pass knows how to reorder stores,
  5718  	// we can do a single store here as long as skip==0.
  5719  	s.storeTypeScalars(t, left, right, skip)
  5720  	if skip&skipPtr == 0 && t.HasPointers() {
  5721  		s.storeTypePtrs(t, left, right)
  5722  	}
  5723  }
  5724  
  5725  // do *left = right for all scalar (non-pointer) parts of t.
  5726  func (s *state) storeTypeScalars(t *types.Type, left, right *ssa.Value, skip skipMask) {
  5727  	switch {
  5728  	case t.IsBoolean() || t.IsInteger() || t.IsFloat() || t.IsComplex() || t.IsSIMD():
  5729  		s.store(t, left, right)
  5730  	case t.IsPtrShaped():
  5731  		if t.IsPtr() && t.Elem().NotInHeap() {
  5732  			s.store(t, left, right) // see issue 42032
  5733  		}
  5734  		// otherwise, no scalar fields.
  5735  	case t.IsString():
  5736  		if skip&skipLen != 0 {
  5737  			return
  5738  		}
  5739  		len := s.newValue1(ssaop.OpStringLen, types.Types[types.TINT], right)
  5740  		lenAddr := s.newValue1I(ssaop.OpOffPtr, s.f.Config.Types.IntPtr, s.config.PtrSize, left)
  5741  		s.store(types.Types[types.TINT], lenAddr, len)
  5742  	case t.IsSlice():
  5743  		if skip&skipLen == 0 {
  5744  			len := s.newValue1(ssaop.OpSliceLen, types.Types[types.TINT], right)
  5745  			lenAddr := s.newValue1I(ssaop.OpOffPtr, s.f.Config.Types.IntPtr, s.config.PtrSize, left)
  5746  			s.store(types.Types[types.TINT], lenAddr, len)
  5747  		}
  5748  		if skip&skipCap == 0 {
  5749  			cap := s.newValue1(ssaop.OpSliceCap, types.Types[types.TINT], right)
  5750  			capAddr := s.newValue1I(ssaop.OpOffPtr, s.f.Config.Types.IntPtr, 2*s.config.PtrSize, left)
  5751  			s.store(types.Types[types.TINT], capAddr, cap)
  5752  		}
  5753  	case t.IsInterface():
  5754  		// itab field doesn't need a write barrier (even though it is a pointer).
  5755  		itab := s.newValue1(ssaop.OpITab, s.f.Config.Types.BytePtr, right)
  5756  		s.store(types.Types[types.TUINTPTR], left, itab)
  5757  	case isStructNotSIMD(t):
  5758  		n := t.NumFields()
  5759  		for i := 0; i < n; i++ {
  5760  			ft := t.FieldType(i)
  5761  			addr := s.newValue1I(ssaop.OpOffPtr, ft.PtrTo(), t.FieldOff(i), left)
  5762  			val := s.newValue1I(ssaop.OpStructSelect, ft, int64(i), right)
  5763  			s.storeTypeScalars(ft, addr, val, 0)
  5764  		}
  5765  	case t.IsArray() && t.Size() == 0:
  5766  		// nothing
  5767  	case t.IsArray() && t.NumElem() == 1:
  5768  		s.storeTypeScalars(t.Elem(), left, s.newValue1I(ssaop.OpArraySelect, t.Elem(), 0, right), 0)
  5769  	default:
  5770  		s.Fatalf("bad write barrier type %v", t)
  5771  	}
  5772  }
  5773  
  5774  // do *left = right for all pointer parts of t.
  5775  func (s *state) storeTypePtrs(t *types.Type, left, right *ssa.Value) {
  5776  	switch {
  5777  	case t.IsPtrShaped():
  5778  		if t.IsPtr() && t.Elem().NotInHeap() {
  5779  			break // see issue 42032
  5780  		}
  5781  		s.store(t, left, right)
  5782  	case t.IsString():
  5783  		ptr := s.newValue1(ssaop.OpStringPtr, s.f.Config.Types.BytePtr, right)
  5784  		s.store(s.f.Config.Types.BytePtr, left, ptr)
  5785  	case t.IsSlice():
  5786  		elType := types.NewPtr(t.Elem())
  5787  		ptr := s.newValue1(ssaop.OpSlicePtr, elType, right)
  5788  		s.store(elType, left, ptr)
  5789  	case t.IsInterface():
  5790  		// itab field is treated as a scalar.
  5791  		idata := s.newValue1(ssaop.OpIData, s.f.Config.Types.BytePtr, right)
  5792  		idataAddr := s.newValue1I(ssaop.OpOffPtr, s.f.Config.Types.BytePtrPtr, s.config.PtrSize, left)
  5793  		s.store(s.f.Config.Types.BytePtr, idataAddr, idata)
  5794  	case isStructNotSIMD(t):
  5795  		n := t.NumFields()
  5796  		for i := 0; i < n; i++ {
  5797  			ft := t.FieldType(i)
  5798  			if !ft.HasPointers() {
  5799  				continue
  5800  			}
  5801  			addr := s.newValue1I(ssaop.OpOffPtr, ft.PtrTo(), t.FieldOff(i), left)
  5802  			val := s.newValue1I(ssaop.OpStructSelect, ft, int64(i), right)
  5803  			s.storeTypePtrs(ft, addr, val)
  5804  		}
  5805  	case t.IsArray() && t.Size() == 0:
  5806  		// nothing
  5807  	case t.IsArray() && t.NumElem() == 1:
  5808  		s.storeTypePtrs(t.Elem(), left, s.newValue1I(ssaop.OpArraySelect, t.Elem(), 0, right))
  5809  	default:
  5810  		s.Fatalf("bad write barrier type %v", t)
  5811  	}
  5812  }
  5813  
  5814  // putArg evaluates n for the purpose of passing it as an argument to a function and returns the value for the call.
  5815  func (s *state) putArg(n ir.Node, t *types.Type) *ssa.Value {
  5816  	var a *ssa.Value
  5817  	if !ssa.CanSSA(t) {
  5818  		a = s.newValue2(ssaop.OpDereference, t, s.addr(n), s.mem())
  5819  	} else {
  5820  		a = s.expr(n)
  5821  	}
  5822  	return a
  5823  }
  5824  
  5825  // slice computes the slice v[i:j:k] and returns ptr, len, and cap of result.
  5826  // i,j,k may be nil, in which case they are set to their default value.
  5827  // v may be a slice, string or pointer to an array.
  5828  func (s *state) slice(v, i, j, k *ssa.Value, bounded bool) (p, l, c *ssa.Value) {
  5829  	t := v.Type
  5830  	var ptr, len, cap *ssa.Value
  5831  	switch {
  5832  	case t.IsSlice():
  5833  		ptr = s.newValue1(ssaop.OpSlicePtr, types.NewPtr(t.Elem()), v)
  5834  		len = s.newValue1(ssaop.OpSliceLen, types.Types[types.TINT], v)
  5835  		cap = s.newValue1(ssaop.OpSliceCap, types.Types[types.TINT], v)
  5836  	case t.IsString():
  5837  		ptr = s.newValue1(ssaop.OpStringPtr, types.NewPtr(types.Types[types.TUINT8]), v)
  5838  		len = s.newValue1(ssaop.OpStringLen, types.Types[types.TINT], v)
  5839  		cap = len
  5840  	case t.IsPtr():
  5841  		if !t.Elem().IsArray() {
  5842  			s.Fatalf("bad ptr to array in slice %v\n", t)
  5843  		}
  5844  		nv := s.nilCheck(v)
  5845  		ptr = s.newValue1(ssaop.OpCopy, types.NewPtr(t.Elem().Elem()), nv)
  5846  		len = s.constInt(types.Types[types.TINT], t.Elem().NumElem())
  5847  		cap = len
  5848  	default:
  5849  		s.Fatalf("bad type in slice %v\n", t)
  5850  	}
  5851  
  5852  	// Set default values
  5853  	if i == nil {
  5854  		i = s.constInt(types.Types[types.TINT], 0)
  5855  	}
  5856  	if j == nil {
  5857  		j = len
  5858  	}
  5859  	three := true
  5860  	if k == nil {
  5861  		three = false
  5862  		k = cap
  5863  	}
  5864  
  5865  	// Panic if slice indices are not in bounds.
  5866  	// Make sure we check these in reverse order so that we're always
  5867  	// comparing against a value known to be nonnegative. See issue 28797.
  5868  	if three {
  5869  		if k != cap {
  5870  			kind := ssa.BoundsSlice3Alen
  5871  			if t.IsSlice() {
  5872  				kind = ssa.BoundsSlice3Acap
  5873  			}
  5874  			k = s.boundsCheck(k, cap, kind, bounded)
  5875  		}
  5876  		if j != k {
  5877  			j = s.boundsCheck(j, k, ssa.BoundsSlice3B, bounded)
  5878  		}
  5879  		i = s.boundsCheck(i, j, ssa.BoundsSlice3C, bounded)
  5880  	} else {
  5881  		if j != k {
  5882  			kind := ssa.BoundsSliceAlen
  5883  			if t.IsSlice() {
  5884  				kind = ssa.BoundsSliceAcap
  5885  			}
  5886  			j = s.boundsCheck(j, k, kind, bounded)
  5887  		}
  5888  		i = s.boundsCheck(i, j, ssa.BoundsSliceB, bounded)
  5889  	}
  5890  
  5891  	// Word-sized integer operations.
  5892  	subOp := s.ssaOp(ir.OSUB, types.Types[types.TINT])
  5893  	mulOp := s.ssaOp(ir.OMUL, types.Types[types.TINT])
  5894  	andOp := s.ssaOp(ir.OAND, types.Types[types.TINT])
  5895  
  5896  	// Calculate the length (rlen) and capacity (rcap) of the new slice.
  5897  	// For strings the capacity of the result is unimportant. However,
  5898  	// we use rcap to test if we've generated a zero-length slice.
  5899  	// Use length of strings for that.
  5900  	rlen := s.newValue2(subOp, types.Types[types.TINT], j, i)
  5901  	rcap := rlen
  5902  	if j != k && !t.IsString() {
  5903  		rcap = s.newValue2(subOp, types.Types[types.TINT], k, i)
  5904  	}
  5905  
  5906  	if (i.Op == ssaop.OpConst64 || i.Op == ssaop.OpConst32) && i.AuxInt == 0 {
  5907  		// No pointer arithmetic necessary.
  5908  		return ptr, rlen, rcap
  5909  	}
  5910  
  5911  	// Calculate the base pointer (rptr) for the new slice.
  5912  	//
  5913  	// Generate the following code assuming that indexes are in bounds.
  5914  	// The masking is to make sure that we don't generate a slice
  5915  	// that points to the next object in memory. We cannot just set
  5916  	// the pointer to nil because then we would create a nil slice or
  5917  	// string.
  5918  	//
  5919  	//     rcap = k - i
  5920  	//     rlen = j - i
  5921  	//     rptr = ptr + (mask(rcap) & (i * stride))
  5922  	//
  5923  	// Where mask(x) is 0 if x==0 and -1 if x>0 and stride is the width
  5924  	// of the element type.
  5925  	stride := s.constInt(types.Types[types.TINT], ptr.Type.Elem().Size())
  5926  
  5927  	// The delta is the number of bytes to offset ptr by.
  5928  	delta := s.newValue2(mulOp, types.Types[types.TINT], i, stride)
  5929  
  5930  	// If we're slicing to the point where the capacity is zero,
  5931  	// zero out the delta.
  5932  	mask := s.newValue1(ssaop.OpSlicemask, types.Types[types.TINT], rcap)
  5933  	delta = s.newValue2(andOp, types.Types[types.TINT], delta, mask)
  5934  
  5935  	// Compute rptr = ptr + delta.
  5936  	rptr := s.newValue2(ssaop.OpAddPtr, ptr.Type, ptr, delta)
  5937  
  5938  	return rptr, rlen, rcap
  5939  }
  5940  
  5941  type u642fcvtTab struct {
  5942  	leq, cvt2F, and, rsh, or, add ssaop.Op
  5943  	one                           func(*state, *types.Type, int64) *ssa.Value
  5944  }
  5945  
  5946  var u64_f64 = u642fcvtTab{
  5947  	leq:   ssaop.OpLeq64,
  5948  	cvt2F: ssaop.OpCvt64to64F,
  5949  	and:   ssaop.OpAnd64,
  5950  	rsh:   ssaop.OpRsh64Ux64,
  5951  	or:    ssaop.OpOr64,
  5952  	add:   ssaop.OpAdd64F,
  5953  	one:   (*state).constInt64,
  5954  }
  5955  
  5956  var u64_f32 = u642fcvtTab{
  5957  	leq:   ssaop.OpLeq64,
  5958  	cvt2F: ssaop.OpCvt64to32F,
  5959  	and:   ssaop.OpAnd64,
  5960  	rsh:   ssaop.OpRsh64Ux64,
  5961  	or:    ssaop.OpOr64,
  5962  	add:   ssaop.OpAdd32F,
  5963  	one:   (*state).constInt64,
  5964  }
  5965  
  5966  func (s *state) uint64Tofloat64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5967  	return s.uint64Tofloat(&u64_f64, n, x, ft, tt)
  5968  }
  5969  
  5970  func (s *state) uint64Tofloat32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5971  	return s.uint64Tofloat(&u64_f32, n, x, ft, tt)
  5972  }
  5973  
  5974  func (s *state) uint64Tofloat(cvttab *u642fcvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5975  	// if x >= 0 {
  5976  	//    result = (floatY) x
  5977  	// } else {
  5978  	// 	  y = uintX(x) ; y = x & 1
  5979  	// 	  z = uintX(x) ; z = z >> 1
  5980  	// 	  z = z | y
  5981  	// 	  result = floatY(z)
  5982  	// 	  result = result + result
  5983  	// }
  5984  	//
  5985  	// Code borrowed from old code generator.
  5986  	// What's going on: large 64-bit "unsigned" looks like
  5987  	// negative number to hardware's integer-to-float
  5988  	// conversion. However, because the mantissa is only
  5989  	// 63 bits, we don't need the LSB, so instead we do an
  5990  	// unsigned right shift (divide by two), convert, and
  5991  	// double. However, before we do that, we need to be
  5992  	// sure that we do not lose a "1" if that made the
  5993  	// difference in the resulting rounding. Therefore, we
  5994  	// preserve it, and OR (not ADD) it back in. The case
  5995  	// that matters is when the eleven discarded bits are
  5996  	// equal to 10000000001; that rounds up, and the 1 cannot
  5997  	// be lost else it would round down if the LSB of the
  5998  	// candidate mantissa is 0.
  5999  
  6000  	cmp := s.newValue2(cvttab.leq, types.Types[types.TBOOL], s.zeroVal(ft), x)
  6001  
  6002  	b := s.endBlock()
  6003  	b.Kind = block.BlockIf
  6004  	b.SetControl(cmp)
  6005  	b.Likely = ssa.BranchLikely
  6006  
  6007  	bThen := s.f.NewBlock(block.BlockPlain)
  6008  	bElse := s.f.NewBlock(block.BlockPlain)
  6009  	bAfter := s.f.NewBlock(block.BlockPlain)
  6010  
  6011  	b.AddEdgeTo(bThen)
  6012  	s.startBlock(bThen)
  6013  	a0 := s.newValue1(cvttab.cvt2F, tt, x)
  6014  	s.vars[n] = a0
  6015  	s.endBlock()
  6016  	bThen.AddEdgeTo(bAfter)
  6017  
  6018  	b.AddEdgeTo(bElse)
  6019  	s.startBlock(bElse)
  6020  	one := cvttab.one(s, ft, 1)
  6021  	y := s.newValue2(cvttab.and, ft, x, one)
  6022  	z := s.newValue2(cvttab.rsh, ft, x, one)
  6023  	z = s.newValue2(cvttab.or, ft, z, y)
  6024  	a := s.newValue1(cvttab.cvt2F, tt, z)
  6025  	a1 := s.newValue2(cvttab.add, tt, a, a)
  6026  	s.vars[n] = a1
  6027  	s.endBlock()
  6028  	bElse.AddEdgeTo(bAfter)
  6029  
  6030  	s.startBlock(bAfter)
  6031  	return s.variable(n, n.Type())
  6032  }
  6033  
  6034  type u322fcvtTab struct {
  6035  	cvtI2F, cvtF2F ssaop.Op
  6036  }
  6037  
  6038  var u32_f64 = u322fcvtTab{
  6039  	cvtI2F: ssaop.OpCvt32to64F,
  6040  	cvtF2F: ssaop.OpCopy,
  6041  }
  6042  
  6043  var u32_f32 = u322fcvtTab{
  6044  	cvtI2F: ssaop.OpCvt32to32F,
  6045  	cvtF2F: ssaop.OpCvt64Fto32F,
  6046  }
  6047  
  6048  func (s *state) uint32Tofloat64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  6049  	return s.uint32Tofloat(&u32_f64, n, x, ft, tt)
  6050  }
  6051  
  6052  func (s *state) uint32Tofloat32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  6053  	return s.uint32Tofloat(&u32_f32, n, x, ft, tt)
  6054  }
  6055  
  6056  func (s *state) uint32Tofloat(cvttab *u322fcvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  6057  	// if x >= 0 {
  6058  	// 	result = floatY(x)
  6059  	// } else {
  6060  	// 	result = floatY(float64(x) + (1<<32))
  6061  	// }
  6062  	cmp := s.newValue2(ssaop.OpLeq32, types.Types[types.TBOOL], s.zeroVal(ft), x)
  6063  	b := s.endBlock()
  6064  	b.Kind = block.BlockIf
  6065  	b.SetControl(cmp)
  6066  	b.Likely = ssa.BranchLikely
  6067  
  6068  	bThen := s.f.NewBlock(block.BlockPlain)
  6069  	bElse := s.f.NewBlock(block.BlockPlain)
  6070  	bAfter := s.f.NewBlock(block.BlockPlain)
  6071  
  6072  	b.AddEdgeTo(bThen)
  6073  	s.startBlock(bThen)
  6074  	a0 := s.newValue1(cvttab.cvtI2F, tt, x)
  6075  	s.vars[n] = a0
  6076  	s.endBlock()
  6077  	bThen.AddEdgeTo(bAfter)
  6078  
  6079  	b.AddEdgeTo(bElse)
  6080  	s.startBlock(bElse)
  6081  	a1 := s.newValue1(ssaop.OpCvt32to64F, types.Types[types.TFLOAT64], x)
  6082  	twoToThe32 := s.constFloat64(types.Types[types.TFLOAT64], float64(1<<32))
  6083  	a2 := s.newValue2(ssaop.OpAdd64F, types.Types[types.TFLOAT64], a1, twoToThe32)
  6084  	a3 := s.newValue1(cvttab.cvtF2F, tt, a2)
  6085  
  6086  	s.vars[n] = a3
  6087  	s.endBlock()
  6088  	bElse.AddEdgeTo(bAfter)
  6089  
  6090  	s.startBlock(bAfter)
  6091  	return s.variable(n, n.Type())
  6092  }
  6093  
  6094  // referenceTypeBuiltin generates code for the len/cap builtins for maps and channels.
  6095  func (s *state) referenceTypeBuiltin(n *ir.UnaryExpr, x *ssa.Value) *ssa.Value {
  6096  	if !n.X.Type().IsMap() && !n.X.Type().IsChan() {
  6097  		s.Fatalf("node must be a map or a channel")
  6098  	}
  6099  	if n.X.Type().IsChan() && n.Op() == ir.OLEN {
  6100  		s.Fatalf("cannot inline len(chan)") // must use runtime.chanlen now
  6101  	}
  6102  	if n.X.Type().IsChan() && n.Op() == ir.OCAP {
  6103  		s.Fatalf("cannot inline cap(chan)") // must use runtime.chancap now
  6104  	}
  6105  	if n.X.Type().IsMap() && n.Op() == ir.OCAP {
  6106  		s.Fatalf("cannot inline cap(map)") // cap(map) does not exist
  6107  	}
  6108  	// if n == nil {
  6109  	//   return 0
  6110  	// } else {
  6111  	//   // len, the actual loadType depends
  6112  	//   return int(*((*loadType)n))
  6113  	//   // cap (chan only, not used for now)
  6114  	//   return *(((*int)n)+1)
  6115  	// }
  6116  	lenType := n.Type()
  6117  	nilValue := s.constNil(types.Types[types.TUINTPTR])
  6118  	cmp := s.newValue2(ssaop.OpEqPtr, types.Types[types.TBOOL], x, nilValue)
  6119  	b := s.endBlock()
  6120  	b.Kind = block.BlockIf
  6121  	b.SetControl(cmp)
  6122  	b.Likely = ssa.BranchUnlikely
  6123  
  6124  	bThen := s.f.NewBlock(block.BlockPlain)
  6125  	bElse := s.f.NewBlock(block.BlockPlain)
  6126  	bAfter := s.f.NewBlock(block.BlockPlain)
  6127  
  6128  	// length/capacity of a nil map/chan is zero
  6129  	b.AddEdgeTo(bThen)
  6130  	s.startBlock(bThen)
  6131  	s.vars[n] = s.zeroVal(lenType)
  6132  	s.endBlock()
  6133  	bThen.AddEdgeTo(bAfter)
  6134  
  6135  	b.AddEdgeTo(bElse)
  6136  	s.startBlock(bElse)
  6137  	switch n.Op() {
  6138  	case ir.OLEN:
  6139  		if n.X.Type().IsMap() {
  6140  			// length is stored in the first word, but needs conversion to int.
  6141  			loadType := reflectdata.MapType().Field(0).Type // uint64
  6142  			load := s.load(loadType, x)
  6143  			s.vars[n] = s.conv(nil, load, loadType, lenType) // integer conversion doesn't need Node
  6144  		} else {
  6145  			// length is stored in the first word for chan, no conversion needed.
  6146  			s.vars[n] = s.load(lenType, x)
  6147  		}
  6148  	case ir.OCAP:
  6149  		// capacity is stored in the second word for chan
  6150  		sw := s.newValue1I(ssaop.OpOffPtr, lenType.PtrTo(), lenType.Size(), x)
  6151  		s.vars[n] = s.load(lenType, sw)
  6152  	default:
  6153  		s.Fatalf("op must be OLEN or OCAP")
  6154  	}
  6155  	s.endBlock()
  6156  	bElse.AddEdgeTo(bAfter)
  6157  
  6158  	s.startBlock(bAfter)
  6159  	return s.variable(n, lenType)
  6160  }
  6161  
  6162  type f2uCvtTab struct {
  6163  	ltf, cvt2U, subf, or ssaop.Op
  6164  	floatValue           func(*state, *types.Type, float64) *ssa.Value
  6165  	intValue             func(*state, *types.Type, int64) *ssa.Value
  6166  	cutoff               uint64
  6167  }
  6168  
  6169  var f32_u64 = f2uCvtTab{
  6170  	ltf:        ssaop.OpLess32F,
  6171  	cvt2U:      ssaop.OpCvt32Fto64,
  6172  	subf:       ssaop.OpSub32F,
  6173  	or:         ssaop.OpOr64,
  6174  	floatValue: (*state).constFloat32,
  6175  	intValue:   (*state).constInt64,
  6176  	cutoff:     1 << 63,
  6177  }
  6178  
  6179  var f64_u64 = f2uCvtTab{
  6180  	ltf:        ssaop.OpLess64F,
  6181  	cvt2U:      ssaop.OpCvt64Fto64,
  6182  	subf:       ssaop.OpSub64F,
  6183  	or:         ssaop.OpOr64,
  6184  	floatValue: (*state).constFloat64,
  6185  	intValue:   (*state).constInt64,
  6186  	cutoff:     1 << 63,
  6187  }
  6188  
  6189  var f32_u32 = f2uCvtTab{
  6190  	ltf:        ssaop.OpLess32F,
  6191  	cvt2U:      ssaop.OpCvt32Fto32,
  6192  	subf:       ssaop.OpSub32F,
  6193  	or:         ssaop.OpOr32,
  6194  	floatValue: (*state).constFloat32,
  6195  	intValue:   func(s *state, t *types.Type, v int64) *ssa.Value { return s.constInt32(t, int32(v)) },
  6196  	cutoff:     1 << 31,
  6197  }
  6198  
  6199  var f64_u32 = f2uCvtTab{
  6200  	ltf:        ssaop.OpLess64F,
  6201  	cvt2U:      ssaop.OpCvt64Fto32,
  6202  	subf:       ssaop.OpSub64F,
  6203  	or:         ssaop.OpOr32,
  6204  	floatValue: (*state).constFloat64,
  6205  	intValue:   func(s *state, t *types.Type, v int64) *ssa.Value { return s.constInt32(t, int32(v)) },
  6206  	cutoff:     1 << 31,
  6207  }
  6208  
  6209  func (s *state) float32ToUint64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  6210  	return s.floatToUint(&f32_u64, n, x, ft, tt)
  6211  }
  6212  func (s *state) float64ToUint64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  6213  	return s.floatToUint(&f64_u64, n, x, ft, tt)
  6214  }
  6215  
  6216  func (s *state) float32ToUint32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  6217  	return s.floatToUint(&f32_u32, n, x, ft, tt)
  6218  }
  6219  
  6220  func (s *state) float64ToUint32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  6221  	return s.floatToUint(&f64_u32, n, x, ft, tt)
  6222  }
  6223  
  6224  func (s *state) floatToUint(cvttab *f2uCvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  6225  	// cutoff:=1<<(intY_Size-1)
  6226  	// if x < floatX(cutoff) {
  6227  	// 	result = uintY(x) // bThen
  6228  	//  // gated by ConvertHash, clamp negative inputs to zero
  6229  	// 	if x < 0 { // unlikely
  6230  	// 		result = 0 // bZero
  6231  	// 	}
  6232  	// } else {
  6233  	// 	y = x - floatX(cutoff) // bElse
  6234  	// 	z = uintY(y)
  6235  	// 	result = z | -(cutoff)
  6236  	// }
  6237  
  6238  	cutoff := cvttab.floatValue(s, ft, float64(cvttab.cutoff))
  6239  	cmp := s.newValueOrSfCall2(cvttab.ltf, types.Types[types.TBOOL], x, cutoff)
  6240  	b := s.endBlock()
  6241  	b.Kind = block.BlockIf
  6242  	b.SetControl(cmp)
  6243  	b.Likely = ssa.BranchLikely
  6244  
  6245  	var bThen, bZero *ssa.Block
  6246  	// use salted hash to distinguish unsigned convert at a Pos from signed convert at a Pos
  6247  	newConversion := base.ConvertHash.MatchPosWithInfo(n.Pos(), "U", nil)
  6248  	if newConversion {
  6249  		bZero = s.f.NewBlock(block.BlockPlain)
  6250  		bThen = s.f.NewBlock(block.BlockIf)
  6251  	} else {
  6252  		bThen = s.f.NewBlock(block.BlockPlain)
  6253  	}
  6254  
  6255  	bElse := s.f.NewBlock(block.BlockPlain)
  6256  	bAfter := s.f.NewBlock(block.BlockPlain)
  6257  
  6258  	b.AddEdgeTo(bThen)
  6259  	s.startBlock(bThen)
  6260  	a0 := s.newValueOrSfCall1(cvttab.cvt2U, tt, x)
  6261  	s.vars[n] = a0
  6262  
  6263  	if newConversion {
  6264  		cmpz := s.newValueOrSfCall2(cvttab.ltf, types.Types[types.TBOOL], x, cvttab.floatValue(s, ft, 0.0))
  6265  		s.endBlock()
  6266  		bThen.SetControl(cmpz)
  6267  		bThen.AddEdgeTo(bZero)
  6268  		bThen.Likely = ssa.BranchUnlikely
  6269  		bThen.AddEdgeTo(bAfter)
  6270  
  6271  		s.startBlock(bZero)
  6272  		s.vars[n] = cvttab.intValue(s, tt, 0)
  6273  		s.endBlock()
  6274  		bZero.AddEdgeTo(bAfter)
  6275  	} else {
  6276  		s.endBlock()
  6277  		bThen.AddEdgeTo(bAfter)
  6278  	}
  6279  
  6280  	b.AddEdgeTo(bElse)
  6281  	s.startBlock(bElse)
  6282  	y := s.newValueOrSfCall2(cvttab.subf, ft, x, cutoff)
  6283  	y = s.newValueOrSfCall1(cvttab.cvt2U, tt, y)
  6284  	z := cvttab.intValue(s, tt, int64(-cvttab.cutoff))
  6285  	a1 := s.newValue2(cvttab.or, tt, y, z)
  6286  	s.vars[n] = a1
  6287  	s.endBlock()
  6288  	bElse.AddEdgeTo(bAfter)
  6289  
  6290  	s.startBlock(bAfter)
  6291  	return s.variable(n, n.Type())
  6292  }
  6293  
  6294  // dottype generates SSA for a type assertion node.
  6295  // commaok indicates whether to panic or return a bool.
  6296  // If commaok is false, resok will be nil.
  6297  func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
  6298  	iface := s.expr(n.X)              // input interface
  6299  	target := s.reflectType(n.Type()) // target type
  6300  	var targetItab *ssa.Value
  6301  	if n.ITab != nil {
  6302  		targetItab = s.expr(n.ITab)
  6303  	}
  6304  
  6305  	if n.UseNilPanic {
  6306  		if commaok {
  6307  			base.Fatalf("unexpected *ir.TypeAssertExpr with UseNilPanic == true && commaok == true")
  6308  		}
  6309  		if n.Type().IsInterface() {
  6310  			// Currently we do not expect the compiler to emit type assertions with UseNilPanic, that asserts to an interface type.
  6311  			// If needed, this can be relaxed in the future, but for now we can't assert that.
  6312  			base.Fatalf("unexpected *ir.TypeAssertExpr with UseNilPanic == true && Type().IsInterface() == true")
  6313  		}
  6314  		typs := s.f.Config.Types
  6315  		iface = s.newValue2(
  6316  			ssaop.OpIMake,
  6317  			iface.Type,
  6318  			s.nilCheck(s.newValue1(ssaop.OpITab, typs.BytePtr, iface)),
  6319  			s.newValue1(ssaop.OpIData, typs.BytePtr, iface),
  6320  		)
  6321  	}
  6322  
  6323  	return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, nil, target, targetItab, commaok, n.Descriptor)
  6324  }
  6325  
  6326  func (s *state) dynamicDottype(n *ir.DynamicTypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
  6327  	iface := s.expr(n.X)
  6328  	var source, target, targetItab *ssa.Value
  6329  	if n.SrcRType != nil {
  6330  		source = s.expr(n.SrcRType)
  6331  	}
  6332  	if !n.X.Type().IsEmptyInterface() && !n.Type().IsInterface() {
  6333  		byteptr := s.f.Config.Types.BytePtr
  6334  		targetItab = s.expr(n.ITab)
  6335  		// TODO(mdempsky): Investigate whether compiling n.RType could be
  6336  		// better than loading itab.typ.
  6337  		target = s.load(byteptr, s.newValue1I(ssaop.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), targetItab))
  6338  	} else {
  6339  		target = s.expr(n.RType)
  6340  	}
  6341  	return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, source, target, targetItab, commaok, nil)
  6342  }
  6343  
  6344  // dottype1 implements a x.(T) operation. iface is the argument (x), dst is the type we're asserting to (T)
  6345  // and src is the type we're asserting from.
  6346  // source is the *runtime._type of src
  6347  // target is the *runtime._type of dst.
  6348  // If src is a nonempty interface and dst is not an interface, targetItab is an itab representing (dst, src). Otherwise it is nil.
  6349  // commaok is true if the caller wants a boolean success value. Otherwise, the generated code panics if the conversion fails.
  6350  // descriptor is a compiler-allocated internal/abi.TypeAssert whose address is passed to runtime.typeAssert when
  6351  // the target type is a compile-time-known non-empty interface. It may be nil.
  6352  func (s *state) dottype1(pos src.XPos, src, dst *types.Type, iface, source, target, targetItab *ssa.Value, commaok bool, descriptor *obj.LSym) (res, resok *ssa.Value) {
  6353  	typs := s.f.Config.Types
  6354  	byteptr := typs.BytePtr
  6355  	if dst.IsInterface() {
  6356  		if dst.IsEmptyInterface() {
  6357  			// Converting to an empty interface.
  6358  			// Input could be an empty or nonempty interface.
  6359  			if base.Debug.TypeAssert > 0 {
  6360  				base.WarnfAt(pos, "type assertion inlined")
  6361  			}
  6362  
  6363  			// Get itab/type field from input.
  6364  			itab := s.newValue1(ssaop.OpITab, byteptr, iface)
  6365  			// Conversion succeeds iff that field is not nil.
  6366  			cond := s.newValue2(ssaop.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  6367  
  6368  			if src.IsEmptyInterface() && commaok {
  6369  				// Converting empty interface to empty interface with ,ok is just a nil check.
  6370  				return iface, cond
  6371  			}
  6372  
  6373  			// Branch on nilness.
  6374  			b := s.endBlock()
  6375  			b.Kind = block.BlockIf
  6376  			b.SetControl(cond)
  6377  			b.Likely = ssa.BranchLikely
  6378  			bOk := s.f.NewBlock(block.BlockPlain)
  6379  			bFail := s.f.NewBlock(block.BlockPlain)
  6380  			b.AddEdgeTo(bOk)
  6381  			b.AddEdgeTo(bFail)
  6382  
  6383  			if !commaok {
  6384  				// On failure, panic by calling panicnildottype.
  6385  				s.startBlock(bFail)
  6386  				s.rtcall(ir.Syms.Panicnildottype, false, nil, target)
  6387  
  6388  				// On success, return (perhaps modified) input interface.
  6389  				s.startBlock(bOk)
  6390  				if src.IsEmptyInterface() {
  6391  					res = iface // Use input interface unchanged.
  6392  					return
  6393  				}
  6394  				// Load type out of itab, build interface with existing idata.
  6395  				off := s.newValue1I(ssaop.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab)
  6396  				typ := s.load(byteptr, off)
  6397  				idata := s.newValue1(ssaop.OpIData, byteptr, iface)
  6398  				res = s.newValue2(ssaop.OpIMake, dst, typ, idata)
  6399  				return
  6400  			}
  6401  
  6402  			s.startBlock(bOk)
  6403  			// nonempty -> empty
  6404  			// Need to load type from itab
  6405  			off := s.newValue1I(ssaop.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab)
  6406  			s.vars[typVar] = s.load(byteptr, off)
  6407  			s.endBlock()
  6408  
  6409  			// itab is nil, might as well use that as the nil result.
  6410  			s.startBlock(bFail)
  6411  			s.vars[typVar] = itab
  6412  			s.endBlock()
  6413  
  6414  			// Merge point.
  6415  			bEnd := s.f.NewBlock(block.BlockPlain)
  6416  			bOk.AddEdgeTo(bEnd)
  6417  			bFail.AddEdgeTo(bEnd)
  6418  			s.startBlock(bEnd)
  6419  			idata := s.newValue1(ssaop.OpIData, byteptr, iface)
  6420  			res = s.newValue2(ssaop.OpIMake, dst, s.variable(typVar, byteptr), idata)
  6421  			resok = cond
  6422  			delete(s.vars, typVar) // no practical effect, just to indicate typVar is no longer live.
  6423  			return
  6424  		}
  6425  		// converting to a nonempty interface needs a runtime call.
  6426  		if base.Debug.TypeAssert > 0 {
  6427  			base.WarnfAt(pos, "type assertion not inlined")
  6428  		}
  6429  
  6430  		itab := s.newValue1(ssaop.OpITab, byteptr, iface)
  6431  		data := s.newValue1(ssaop.OpIData, types.Types[types.TUNSAFEPTR], iface)
  6432  
  6433  		// First, check for nil.
  6434  		bNil := s.f.NewBlock(block.BlockPlain)
  6435  		bNonNil := s.f.NewBlock(block.BlockPlain)
  6436  		bMerge := s.f.NewBlock(block.BlockPlain)
  6437  		cond := s.newValue2(ssaop.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  6438  		b := s.endBlock()
  6439  		b.Kind = block.BlockIf
  6440  		b.SetControl(cond)
  6441  		b.Likely = ssa.BranchLikely
  6442  		b.AddEdgeTo(bNonNil)
  6443  		b.AddEdgeTo(bNil)
  6444  
  6445  		s.startBlock(bNil)
  6446  		if commaok {
  6447  			s.vars[typVar] = itab // which will be nil
  6448  			b := s.endBlock()
  6449  			b.AddEdgeTo(bMerge)
  6450  		} else {
  6451  			// Panic if input is nil.
  6452  			s.rtcall(ir.Syms.Panicnildottype, false, nil, target)
  6453  		}
  6454  
  6455  		// Get typ, possibly by loading out of itab.
  6456  		s.startBlock(bNonNil)
  6457  		typ := itab
  6458  		if !src.IsEmptyInterface() {
  6459  			typ = s.load(byteptr, s.newValue1I(ssaop.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab))
  6460  		}
  6461  
  6462  		// Check the cache first.
  6463  		var d *ssa.Value
  6464  		if descriptor != nil {
  6465  			d = s.newValue1A(ssaop.OpAddr, byteptr, descriptor, s.sb)
  6466  			if base.Flag.N == 0 && rtabi.UseInterfaceSwitchCache(Arch.LinkArch.Family) {
  6467  				// Note: we can only use the cache if we have the right atomic load instruction.
  6468  				// Double-check that here.
  6469  				if intrinsics.lookup(Arch.LinkArch.Arch, "internal/runtime/atomic", "Loadp") == nil {
  6470  					s.Fatalf("atomic load not available")
  6471  				}
  6472  				// Pick right size ops.
  6473  				var mul, and, add, zext ssaop.Op
  6474  				if s.config.PtrSize == 4 {
  6475  					mul = ssaop.OpMul32
  6476  					and = ssaop.OpAnd32
  6477  					add = ssaop.OpAdd32
  6478  					zext = ssaop.OpCopy
  6479  				} else {
  6480  					mul = ssaop.OpMul64
  6481  					and = ssaop.OpAnd64
  6482  					add = ssaop.OpAdd64
  6483  					zext = ssaop.OpZeroExt32to64
  6484  				}
  6485  
  6486  				loopHead := s.f.NewBlock(block.BlockPlain)
  6487  				loopBody := s.f.NewBlock(block.BlockPlain)
  6488  				cacheHit := s.f.NewBlock(block.BlockPlain)
  6489  				cacheMiss := s.f.NewBlock(block.BlockPlain)
  6490  
  6491  				// Load cache pointer out of descriptor, with an atomic load so
  6492  				// we ensure that we see a fully written cache.
  6493  				atomicLoad := s.newValue2(ssaop.OpAtomicLoadPtr, types.NewTuple(typs.BytePtr, types.TypeMem), d, s.mem())
  6494  				cache := s.newValue1(ssaop.OpSelect0, typs.BytePtr, atomicLoad)
  6495  				s.vars[memVar] = s.newValue1(ssaop.OpSelect1, types.TypeMem, atomicLoad)
  6496  
  6497  				// Load hash from type or itab.
  6498  				var hash *ssa.Value
  6499  				if src.IsEmptyInterface() {
  6500  					hash = s.newValue2(ssaop.OpLoad, typs.UInt32, s.newValue1I(ssaop.OpOffPtr, typs.UInt32Ptr, rttype.Type.OffsetOf("Hash"), typ), s.mem())
  6501  				} else {
  6502  					hash = s.newValue2(ssaop.OpLoad, typs.UInt32, s.newValue1I(ssaop.OpOffPtr, typs.UInt32Ptr, rttype.ITab.OffsetOf("Hash"), itab), s.mem())
  6503  				}
  6504  				hash = s.newValue1(zext, typs.Uintptr, hash)
  6505  				s.vars[hashVar] = hash
  6506  				// Load mask from cache.
  6507  				mask := s.newValue2(ssaop.OpLoad, typs.Uintptr, cache, s.mem())
  6508  				// Jump to loop head.
  6509  				b := s.endBlock()
  6510  				b.AddEdgeTo(loopHead)
  6511  
  6512  				// At loop head, get pointer to the cache entry.
  6513  				//   e := &cache.Entries[hash&mask]
  6514  				s.startBlock(loopHead)
  6515  				idx := s.newValue2(and, typs.Uintptr, s.variable(hashVar, typs.Uintptr), mask)
  6516  				idx = s.newValue2(mul, typs.Uintptr, idx, s.uintptrConstant(uint64(2*s.config.PtrSize)))
  6517  				idx = s.newValue2(add, typs.Uintptr, idx, s.uintptrConstant(uint64(s.config.PtrSize)))
  6518  				e := s.newValue2(ssaop.OpAddPtr, typs.UintptrPtr, cache, idx)
  6519  				//   hash++
  6520  				s.vars[hashVar] = s.newValue2(add, typs.Uintptr, s.variable(hashVar, typs.Uintptr), s.uintptrConstant(1))
  6521  
  6522  				// Look for a cache hit.
  6523  				//   if e.Typ == typ { goto hit }
  6524  				eTyp := s.newValue2(ssaop.OpLoad, typs.Uintptr, e, s.mem())
  6525  				cmp1 := s.newValue2(ssaop.OpEqPtr, typs.Bool, typ, eTyp)
  6526  				b = s.endBlock()
  6527  				b.Kind = block.BlockIf
  6528  				b.SetControl(cmp1)
  6529  				b.AddEdgeTo(cacheHit)
  6530  				b.AddEdgeTo(loopBody)
  6531  
  6532  				// Look for an empty entry, the tombstone for this hash table.
  6533  				//   if e.Typ == nil { goto miss }
  6534  				s.startBlock(loopBody)
  6535  				cmp2 := s.newValue2(ssaop.OpEqPtr, typs.Bool, eTyp, s.constNil(typs.BytePtr))
  6536  				b = s.endBlock()
  6537  				b.Kind = block.BlockIf
  6538  				b.SetControl(cmp2)
  6539  				b.AddEdgeTo(cacheMiss)
  6540  				b.AddEdgeTo(loopHead)
  6541  
  6542  				// On a hit, load the data fields of the cache entry.
  6543  				//   Itab = e.Itab
  6544  				s.startBlock(cacheHit)
  6545  				eItab := s.newValue2(ssaop.OpLoad, typs.BytePtr, s.newValue1I(ssaop.OpOffPtr, typs.BytePtrPtr, s.config.PtrSize, e), s.mem())
  6546  				s.vars[typVar] = eItab
  6547  				b = s.endBlock()
  6548  				b.AddEdgeTo(bMerge)
  6549  
  6550  				// On a miss, call into the runtime to get the answer.
  6551  				s.startBlock(cacheMiss)
  6552  			}
  6553  		}
  6554  
  6555  		// Call into runtime to get itab for result.
  6556  		if descriptor != nil {
  6557  			itab = s.rtcall(ir.Syms.TypeAssert, true, []*types.Type{byteptr}, d, typ)[0]
  6558  		} else {
  6559  			var fn *obj.LSym
  6560  			if commaok {
  6561  				fn = ir.Syms.AssertE2I2
  6562  			} else {
  6563  				fn = ir.Syms.AssertE2I
  6564  			}
  6565  			itab = s.rtcall(fn, true, []*types.Type{byteptr}, target, typ)[0]
  6566  		}
  6567  		s.vars[typVar] = itab
  6568  		b = s.endBlock()
  6569  		b.AddEdgeTo(bMerge)
  6570  
  6571  		// Build resulting interface.
  6572  		s.startBlock(bMerge)
  6573  		itab = s.variable(typVar, byteptr)
  6574  		var ok *ssa.Value
  6575  		if commaok {
  6576  			ok = s.newValue2(ssaop.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  6577  		}
  6578  		return s.newValue2(ssaop.OpIMake, dst, itab, data), ok
  6579  	}
  6580  
  6581  	if base.Debug.TypeAssert > 0 {
  6582  		base.WarnfAt(pos, "type assertion inlined")
  6583  	}
  6584  
  6585  	// Converting to a concrete type.
  6586  	direct := types.IsDirectIface(dst)
  6587  	itab := s.newValue1(ssaop.OpITab, byteptr, iface) // type word of interface
  6588  	if base.Debug.TypeAssert > 0 {
  6589  		base.WarnfAt(pos, "type assertion inlined")
  6590  	}
  6591  	var wantedFirstWord *ssa.Value
  6592  	if src.IsEmptyInterface() {
  6593  		// Looking for pointer to target type.
  6594  		wantedFirstWord = target
  6595  	} else {
  6596  		// Looking for pointer to itab for target type and source interface.
  6597  		wantedFirstWord = targetItab
  6598  	}
  6599  
  6600  	var tmp ir.Node     // temporary for use with large types
  6601  	var addr *ssa.Value // address of tmp
  6602  	if commaok && !ssa.CanSSA(dst) {
  6603  		// unSSAable type, use temporary.
  6604  		// TODO: get rid of some of these temporaries.
  6605  		tmp, addr = s.temp(pos, dst)
  6606  	}
  6607  
  6608  	cond := s.newValue2(ssaop.OpEqPtr, types.Types[types.TBOOL], itab, wantedFirstWord)
  6609  	b := s.endBlock()
  6610  	b.Kind = block.BlockIf
  6611  	b.SetControl(cond)
  6612  	b.Likely = ssa.BranchLikely
  6613  
  6614  	bOk := s.f.NewBlock(block.BlockPlain)
  6615  	bFail := s.f.NewBlock(block.BlockPlain)
  6616  	b.AddEdgeTo(bOk)
  6617  	b.AddEdgeTo(bFail)
  6618  
  6619  	if !commaok {
  6620  		// on failure, panic by calling panicdottype
  6621  		s.startBlock(bFail)
  6622  		taddr := source
  6623  		if taddr == nil {
  6624  			taddr = s.reflectType(src)
  6625  		}
  6626  		if src.IsEmptyInterface() {
  6627  			s.rtcall(ir.Syms.PanicdottypeE, false, nil, itab, target, taddr)
  6628  		} else {
  6629  			s.rtcall(ir.Syms.PanicdottypeI, false, nil, itab, target, taddr)
  6630  		}
  6631  
  6632  		// on success, return data from interface
  6633  		s.startBlock(bOk)
  6634  		if direct {
  6635  			return s.newValue1(ssaop.OpIData, dst, iface), nil
  6636  		}
  6637  		p := s.newValue1(ssaop.OpIData, types.NewPtr(dst), iface)
  6638  		return s.load(dst, p), nil
  6639  	}
  6640  
  6641  	// commaok is the more complicated case because we have
  6642  	// a control flow merge point.
  6643  	bEnd := s.f.NewBlock(block.BlockPlain)
  6644  	// Note that we need a new valVar each time (unlike okVar where we can
  6645  	// reuse the variable) because it might have a different type every time.
  6646  	valVar := ssaMarker("val")
  6647  
  6648  	// type assertion succeeded
  6649  	s.startBlock(bOk)
  6650  	if tmp == nil {
  6651  		if direct {
  6652  			s.vars[valVar] = s.newValue1(ssaop.OpIData, dst, iface)
  6653  		} else {
  6654  			p := s.newValue1(ssaop.OpIData, types.NewPtr(dst), iface)
  6655  			s.vars[valVar] = s.load(dst, p)
  6656  		}
  6657  	} else {
  6658  		p := s.newValue1(ssaop.OpIData, types.NewPtr(dst), iface)
  6659  		s.move(dst, addr, p)
  6660  	}
  6661  	s.vars[okVar] = s.constBool(true)
  6662  	s.endBlock()
  6663  	bOk.AddEdgeTo(bEnd)
  6664  
  6665  	// type assertion failed
  6666  	s.startBlock(bFail)
  6667  	if tmp == nil {
  6668  		s.vars[valVar] = s.zeroVal(dst)
  6669  	} else {
  6670  		s.zero(dst, addr)
  6671  	}
  6672  	s.vars[okVar] = s.constBool(false)
  6673  	s.endBlock()
  6674  	bFail.AddEdgeTo(bEnd)
  6675  
  6676  	// merge point
  6677  	s.startBlock(bEnd)
  6678  	if tmp == nil {
  6679  		res = s.variable(valVar, dst)
  6680  		delete(s.vars, valVar) // no practical effect, just to indicate typVar is no longer live.
  6681  	} else {
  6682  		res = s.load(dst, addr)
  6683  	}
  6684  	resok = s.variable(okVar, types.Types[types.TBOOL])
  6685  	delete(s.vars, okVar) // ditto
  6686  	return res, resok
  6687  }
  6688  
  6689  // temp allocates a temp of type t at position pos
  6690  func (s *state) temp(pos src.XPos, t *types.Type) (*ir.Name, *ssa.Value) {
  6691  	tmp := typecheck.TempAt(pos, s.curfn, t)
  6692  	if ssa.CanSSA(t) {
  6693  		// The whole point of this temporary is that we are about to take
  6694  		// its address (see the s.addr call below), so it must live on the
  6695  		// stack. typecheck.TempAt does not mark it addrtaken, and for an
  6696  		// SSA-able type that makes s.addr take its s.canSSA early-return
  6697  		// path and hand back &runtime.zerobase instead of the temporary's
  6698  		// stack slot, after which the caller writes the object into
  6699  		// runtime.zerobase.
  6700  		//
  6701  		// A type that is not SSA-able already gets a real stack slot, and
  6702  		// marking it here would only cost it its stack-slot merging
  6703  		// candidacy (see ssa.IsMergeCandidate below), so leave it alone.
  6704  		tmp.SetAddrtaken(true)
  6705  	}
  6706  	if t.HasPointers() || (ssa.IsMergeCandidate(tmp) && t != deferstruct()) {
  6707  		s.vars[memVar] = s.newValue1A(ssaop.OpVarDef, types.TypeMem, tmp, s.mem())
  6708  	}
  6709  	addr := s.addr(tmp)
  6710  	return tmp, addr
  6711  }
  6712  
  6713  // variable returns the value of a variable at the current location.
  6714  func (s *state) variable(n ir.Node, t *types.Type) *ssa.Value {
  6715  	v := s.vars[n]
  6716  	if v != nil {
  6717  		return v
  6718  	}
  6719  	v = s.fwdVars[n]
  6720  	if v != nil {
  6721  		return v
  6722  	}
  6723  
  6724  	if s.curBlock == s.f.Entry {
  6725  		// No variable should be live at entry.
  6726  		s.f.Fatalf("value %v (%v) incorrectly live at entry", n, v)
  6727  	}
  6728  	// Make a FwdRef, which records a value that's live on block input.
  6729  	// We'll find the matching definition as part of insertPhis.
  6730  	v = s.newValue0A(ssaop.OpFwdRef, t, fwdRefAux{N: n})
  6731  	s.fwdVars[n] = v
  6732  	if n.Op() == ir.ONAME {
  6733  		s.addNamedValue(n.(*ir.Name), v)
  6734  	}
  6735  	return v
  6736  }
  6737  
  6738  func (s *state) mem() *ssa.Value {
  6739  	return s.variable(memVar, types.TypeMem)
  6740  }
  6741  
  6742  func (s *state) addNamedValue(n *ir.Name, v *ssa.Value) {
  6743  	if n.Class == ir.Pxxx {
  6744  		// Don't track our marker nodes (memVar etc.).
  6745  		return
  6746  	}
  6747  	if ir.IsAutoTmp(n) {
  6748  		// Don't track temporary variables.
  6749  		return
  6750  	}
  6751  	if n.Class == ir.PPARAMOUT {
  6752  		// Don't track named output values.  This prevents return values
  6753  		// from being assigned too early. See #14591 and #14762. TODO: allow this.
  6754  		return
  6755  	}
  6756  	loc := ssa.LocalSlot{N: n, Type: n.Type(), Off: 0}
  6757  	values, ok := s.f.NamedValues[loc]
  6758  	if !ok {
  6759  		s.f.Names = append(s.f.Names, loc)
  6760  	}
  6761  	s.f.NamedValues[loc] = append(values, v)
  6762  }
  6763  
  6764  // Branch is an unresolved branch.
  6765  type Branch struct {
  6766  	P *obj.Prog  // branch instruction
  6767  	B *ssa.Block // target
  6768  }
  6769  
  6770  // State contains state needed during Prog generation.
  6771  type State struct {
  6772  	ABI obj.ABI
  6773  
  6774  	pp *objw.Progs
  6775  
  6776  	// Branches remembers all the branch instructions we've seen
  6777  	// and where they would like to go.
  6778  	Branches []Branch
  6779  
  6780  	// JumpTables remembers all the jump tables we've seen.
  6781  	JumpTables []*ssa.Block
  6782  
  6783  	// bstart remembers where each block starts (indexed by block ID)
  6784  	bstart []*obj.Prog
  6785  
  6786  	maxarg int64 // largest frame size for arguments to calls made by the function
  6787  
  6788  	// Map from GC safe points to liveness index, generated by
  6789  	// liveness analysis.
  6790  	livenessMap liveness.Map
  6791  
  6792  	// partLiveArgs includes arguments that may be partially live, for which we
  6793  	// need to generate instructions that spill the argument registers.
  6794  	partLiveArgs map[*ir.Name]bool
  6795  
  6796  	// lineRunStart records the beginning of the current run of instructions
  6797  	// within a single block sharing the same line number
  6798  	// Used to move statement marks to the beginning of such runs.
  6799  	lineRunStart *obj.Prog
  6800  
  6801  	// wasm: The number of values on the WebAssembly stack. This is only used as a safeguard.
  6802  	OnWasmStackSkipped int
  6803  }
  6804  
  6805  func (s *State) FuncInfo() *obj.FuncInfo {
  6806  	return s.pp.CurFunc.LSym.Func()
  6807  }
  6808  
  6809  // Prog appends a new Prog.
  6810  func (s *State) Prog(as obj.As) *obj.Prog {
  6811  	p := s.pp.Prog(as)
  6812  	if objw.LosesStmtMark(as) {
  6813  		return p
  6814  	}
  6815  	// Float a statement start to the beginning of any same-line run.
  6816  	// lineRunStart is reset at block boundaries, which appears to work well.
  6817  	if s.lineRunStart == nil || s.lineRunStart.Pos.Line() != p.Pos.Line() {
  6818  		s.lineRunStart = p
  6819  	} else if p.Pos.IsStmt() == src.PosIsStmt {
  6820  		s.lineRunStart.Pos = s.lineRunStart.Pos.WithIsStmt()
  6821  		p.Pos = p.Pos.WithNotStmt()
  6822  	}
  6823  	return p
  6824  }
  6825  
  6826  // Pc returns the current Prog.
  6827  func (s *State) Pc() *obj.Prog {
  6828  	return s.pp.Next
  6829  }
  6830  
  6831  // SetPos sets the current source position.
  6832  func (s *State) SetPos(pos src.XPos) {
  6833  	s.pp.Pos = pos
  6834  }
  6835  
  6836  // Br emits a single branch instruction and returns the instruction.
  6837  // Not all architectures need the returned instruction, but otherwise
  6838  // the boilerplate is common to all.
  6839  func (s *State) Br(op obj.As, target *ssa.Block) *obj.Prog {
  6840  	p := s.Prog(op)
  6841  	p.To.Type = obj.TYPE_BRANCH
  6842  	s.Branches = append(s.Branches, Branch{P: p, B: target})
  6843  	return p
  6844  }
  6845  
  6846  // DebugFriendlySetPosFrom adjusts Pos.IsStmt subject to heuristics
  6847  // that reduce "jumpy" line number churn when debugging.
  6848  // Spill/fill/copy instructions from the register allocator,
  6849  // phi functions, and instructions with a no-pos position
  6850  // are examples of instructions that can cause churn.
  6851  func (s *State) DebugFriendlySetPosFrom(v *ssa.Value) {
  6852  	switch v.Op {
  6853  	case ssaop.OpPhi, ssaop.OpCopy, ssaop.OpLoadReg, ssaop.OpStoreReg:
  6854  		// These are not statements
  6855  		s.SetPos(v.Pos.WithNotStmt())
  6856  	default:
  6857  		p := v.Pos
  6858  		if p != src.NoXPos {
  6859  			// If the position is defined, update the position.
  6860  			// Also convert default IsStmt to NotStmt; only
  6861  			// explicit statement boundaries should appear
  6862  			// in the generated code.
  6863  			if p.IsStmt() != src.PosIsStmt {
  6864  				if s.pp.Pos.IsStmt() == src.PosIsStmt && s.pp.Pos.SameFileAndLine(p) {
  6865  					// If s.pp.Pos already has a statement mark, then it was set here (below) for
  6866  					// the previous value.  If an actual instruction had been emitted for that
  6867  					// value, then the statement mark would have been reset.  Since the statement
  6868  					// mark of s.pp.Pos was not reset, this position (file/line) still needs a
  6869  					// statement mark on an instruction.  If file and line for this value are
  6870  					// the same as the previous value, then the first instruction for this
  6871  					// value will work to take the statement mark.  Return early to avoid
  6872  					// resetting the statement mark.
  6873  					//
  6874  					// The reset of s.pp.Pos occurs in (*Progs).Prog() -- if it emits
  6875  					// an instruction, and the instruction's statement mark was set,
  6876  					// and it is not one of the LosesStmtMark instructions,
  6877  					// then Prog() resets the statement mark on the (*Progs).Pos.
  6878  					return
  6879  				}
  6880  				p = p.WithNotStmt()
  6881  				// Calls use the pos attached to v, but copy the statement mark from State
  6882  			}
  6883  			s.SetPos(p)
  6884  		} else {
  6885  			s.SetPos(s.pp.Pos.WithNotStmt())
  6886  		}
  6887  	}
  6888  }
  6889  
  6890  // emit argument info (locations on stack) for traceback.
  6891  func emitArgInfo(e *ssafn, f *ssa.Func, pp *objw.Progs) {
  6892  	ft := e.curfn.Type()
  6893  	if ft.NumRecvs() == 0 && ft.NumParams() == 0 {
  6894  		return
  6895  	}
  6896  
  6897  	x := EmitArgInfo(e.curfn, f.OwnAux.ABIInfo())
  6898  	x.Set(obj.AttrContentAddressable, true)
  6899  	e.curfn.LSym.Func().ArgInfo = x
  6900  
  6901  	// Emit a funcdata pointing at the arg info data.
  6902  	p := pp.Prog(obj.AFUNCDATA)
  6903  	p.From.SetConst(rtabi.FUNCDATA_ArgInfo)
  6904  	p.To.Type = obj.TYPE_MEM
  6905  	p.To.Name = obj.NAME_EXTERN
  6906  	p.To.Sym = x
  6907  }
  6908  
  6909  // emit argument info (locations on stack) of f for traceback.
  6910  func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
  6911  	x := base.Ctxt.Lookup(fmt.Sprintf("%s.arginfo%d", f.LSym.Name, f.ABI))
  6912  	x.Align = 1
  6913  	// NOTE: do not set ContentAddressable here. This may be referenced from
  6914  	// assembly code by name (in this case f is a declaration).
  6915  	// Instead, set it in emitArgInfo above.
  6916  
  6917  	PtrSize := int64(types.PtrSize)
  6918  	uintptrTyp := types.Types[types.TUINTPTR]
  6919  
  6920  	isAggregate := func(t *types.Type) bool {
  6921  		return isStructNotSIMD(t) || t.IsArray() || t.IsComplex() || t.IsInterface() || t.IsString() || t.IsSlice()
  6922  	}
  6923  
  6924  	wOff := 0
  6925  	n := 0
  6926  	writebyte := func(o uint8) { wOff = objw.Uint8(x, wOff, o) }
  6927  
  6928  	// Write one non-aggregate arg/field/element.
  6929  	write1 := func(sz, offset int64) {
  6930  		if offset >= rtabi.TraceArgsSpecial {
  6931  			writebyte(rtabi.TraceArgsOffsetTooLarge)
  6932  		} else {
  6933  			writebyte(uint8(offset))
  6934  			writebyte(uint8(sz))
  6935  		}
  6936  		n++
  6937  	}
  6938  
  6939  	// Visit t recursively and write it out.
  6940  	// Returns whether to continue visiting.
  6941  	var visitType func(baseOffset int64, t *types.Type, depth int) bool
  6942  	visitType = func(baseOffset int64, t *types.Type, depth int) bool {
  6943  		if n >= rtabi.TraceArgsLimit {
  6944  			writebyte(rtabi.TraceArgsDotdotdot)
  6945  			return false
  6946  		}
  6947  		if !isAggregate(t) {
  6948  			write1(t.Size(), baseOffset)
  6949  			return true
  6950  		}
  6951  		writebyte(rtabi.TraceArgsStartAgg)
  6952  		depth++
  6953  		if depth >= rtabi.TraceArgsMaxDepth {
  6954  			writebyte(rtabi.TraceArgsDotdotdot)
  6955  			writebyte(rtabi.TraceArgsEndAgg)
  6956  			n++
  6957  			return true
  6958  		}
  6959  		switch {
  6960  		case t.IsInterface(), t.IsString():
  6961  			_ = visitType(baseOffset, uintptrTyp, depth) &&
  6962  				visitType(baseOffset+PtrSize, uintptrTyp, depth)
  6963  		case t.IsSlice():
  6964  			_ = visitType(baseOffset, uintptrTyp, depth) &&
  6965  				visitType(baseOffset+PtrSize, uintptrTyp, depth) &&
  6966  				visitType(baseOffset+PtrSize*2, uintptrTyp, depth)
  6967  		case t.IsComplex():
  6968  			_ = visitType(baseOffset, types.FloatForComplex(t), depth) &&
  6969  				visitType(baseOffset+t.Size()/2, types.FloatForComplex(t), depth)
  6970  		case t.IsArray():
  6971  			if t.NumElem() == 0 {
  6972  				n++ // {} counts as a component
  6973  				break
  6974  			}
  6975  			for i := int64(0); i < t.NumElem(); i++ {
  6976  				if !visitType(baseOffset, t.Elem(), depth) {
  6977  					break
  6978  				}
  6979  				baseOffset += t.Elem().Size()
  6980  			}
  6981  		case isStructNotSIMD(t):
  6982  			if t.NumFields() == 0 {
  6983  				n++ // {} counts as a component
  6984  				break
  6985  			}
  6986  			for _, field := range t.Fields() {
  6987  				if !visitType(baseOffset+field.Offset, field.Type, depth) {
  6988  					break
  6989  				}
  6990  			}
  6991  		}
  6992  		writebyte(rtabi.TraceArgsEndAgg)
  6993  		return true
  6994  	}
  6995  
  6996  	start := 0
  6997  	if strings.Contains(f.LSym.Name, "[") {
  6998  		// Skip the dictionary argument - it is implicit and the user doesn't need to see it.
  6999  		start = 1
  7000  	}
  7001  
  7002  	for _, a := range abiInfo.InParams()[start:] {
  7003  		if !visitType(a.FrameOffset(abiInfo), a.Type, 0) {
  7004  			break
  7005  		}
  7006  	}
  7007  	writebyte(rtabi.TraceArgsEndSeq)
  7008  	if wOff > rtabi.TraceArgsMaxLen {
  7009  		base.Fatalf("ArgInfo too large")
  7010  	}
  7011  
  7012  	return x
  7013  }
  7014  
  7015  // for wrapper, emit info of wrapped function.
  7016  func emitWrappedFuncInfo(e *ssafn, pp *objw.Progs) {
  7017  	if base.Ctxt.Flag_linkshared {
  7018  		// Relative reference (SymPtrOff) to another shared object doesn't work.
  7019  		// Unfortunate.
  7020  		return
  7021  	}
  7022  
  7023  	wfn := e.curfn.WrappedFunc
  7024  	if wfn == nil {
  7025  		return
  7026  	}
  7027  
  7028  	wsym := wfn.Linksym()
  7029  	x := base.Ctxt.LookupInit(fmt.Sprintf("%s.wrapinfo", wsym.Name), func(x *obj.LSym) {
  7030  		objw.SymPtrOff(x, 0, wsym)
  7031  		x.Set(obj.AttrContentAddressable, true)
  7032  		x.Align = 4
  7033  	})
  7034  	e.curfn.LSym.Func().WrapInfo = x
  7035  
  7036  	// Emit a funcdata pointing at the wrap info data.
  7037  	p := pp.Prog(obj.AFUNCDATA)
  7038  	p.From.SetConst(rtabi.FUNCDATA_WrapInfo)
  7039  	p.To.Type = obj.TYPE_MEM
  7040  	p.To.Name = obj.NAME_EXTERN
  7041  	p.To.Sym = x
  7042  }
  7043  
  7044  // genssa appends entries to pp for each instruction in f.
  7045  func genssa(htmlWriter ssa.HTMLWriter, f *ssa.Func, pp *objw.Progs) {
  7046  	var s State
  7047  	s.ABI = f.OwnAux.Fn.ABI()
  7048  
  7049  	e := f.Frontend().(*ssafn)
  7050  
  7051  	gatherPrintInfo := f.PrintOrHtmlSSA || ssaconfig.GenssaDump[f.Name]
  7052  
  7053  	var lv *liveness.Liveness
  7054  	s.livenessMap, s.partLiveArgs, lv = liveness.Compute(e.curfn, f, e.stkptrsize, pp, gatherPrintInfo)
  7055  	emitArgInfo(e, f, pp)
  7056  	argLiveBlockMap, argLiveValueMap := liveness.ArgLiveness(e.curfn, f, pp)
  7057  
  7058  	openDeferInfo := e.curfn.LSym.Func().OpenCodedDeferInfo
  7059  	if openDeferInfo != nil {
  7060  		// This function uses open-coded defers -- write out the funcdata
  7061  		// info that we computed at the end of genssa.
  7062  		p := pp.Prog(obj.AFUNCDATA)
  7063  		p.From.SetConst(rtabi.FUNCDATA_OpenCodedDeferInfo)
  7064  		p.To.Type = obj.TYPE_MEM
  7065  		p.To.Name = obj.NAME_EXTERN
  7066  		p.To.Sym = openDeferInfo
  7067  	}
  7068  
  7069  	emitWrappedFuncInfo(e, pp)
  7070  
  7071  	// Remember where each block starts.
  7072  	s.bstart = make([]*obj.Prog, f.NumBlocks())
  7073  	s.pp = pp
  7074  	var progToValue map[*obj.Prog]*ssa.Value
  7075  	var progToBlock map[*obj.Prog]*ssa.Block
  7076  	var valueToProgAfter []*obj.Prog // The first Prog following computation of a value v; v is visible at this point.
  7077  	if gatherPrintInfo {
  7078  		progToValue = make(map[*obj.Prog]*ssa.Value, f.NumValues())
  7079  		progToBlock = make(map[*obj.Prog]*ssa.Block, f.NumBlocks())
  7080  		f.Logf("genssa %s\n", f.Name)
  7081  		progToBlock[s.pp.Next] = f.Blocks[0]
  7082  	}
  7083  
  7084  	if base.Ctxt.Flag_locationlists {
  7085  		if cap(f.Cache.ValueToProgAfter) < f.NumValues() {
  7086  			f.Cache.ValueToProgAfter = make([]*obj.Prog, f.NumValues())
  7087  		}
  7088  		valueToProgAfter = f.Cache.ValueToProgAfter[:f.NumValues()]
  7089  		clear(valueToProgAfter)
  7090  	}
  7091  
  7092  	// If the very first instruction is not tagged as a statement,
  7093  	// debuggers may attribute it to previous function in program.
  7094  	firstPos := src.NoXPos
  7095  	for _, v := range f.Entry.Values {
  7096  		if v.Pos.IsStmt() == src.PosIsStmt && v.Op != ssaop.OpArg && v.Op != ssaop.OpArgIntReg && v.Op != ssaop.OpArgFloatReg && v.Op != ssaop.OpLoadReg && v.Op != ssaop.OpStoreReg {
  7097  			firstPos = v.Pos
  7098  			v.Pos = firstPos.WithDefaultStmt()
  7099  			break
  7100  		}
  7101  	}
  7102  
  7103  	// inlMarks has an entry for each Prog that implements an inline mark.
  7104  	// It maps from that Prog to the global inlining id of the inlined body
  7105  	// which should unwind to this Prog's location.
  7106  	var inlMarks map[*obj.Prog]int32
  7107  	var inlMarkList []*obj.Prog
  7108  
  7109  	// inlMarksByPos maps from a (column 1) source position to the set of
  7110  	// Progs that are in the set above and have that source position.
  7111  	var inlMarksByPos map[src.XPos][]*obj.Prog
  7112  
  7113  	var argLiveIdx int = -1 // argument liveness info index
  7114  
  7115  	// These control cache line alignment; if the required portion of
  7116  	// a cache line is not available, then pad to obtain cache line
  7117  	// alignment.  Not implemented on all architectures, may not be
  7118  	// useful on all architectures.
  7119  	var hotAlign, hotRequire int64
  7120  
  7121  	if base.Debug.AlignHot > 0 {
  7122  		switch base.Ctxt.Arch.Name {
  7123  		// enable this on a case-by-case basis, with benchmarking.
  7124  		// currently shown:
  7125  		//   good for amd64
  7126  		//   not helpful for Apple Silicon
  7127  		//
  7128  		case "amd64", "386":
  7129  			// Align to 64 if 31 or fewer bytes remain in a cache line
  7130  			// benchmarks a little better than always aligning, and also
  7131  			// adds slightly less to the (PGO-compiled) binary size.
  7132  			hotAlign = 64
  7133  			hotRequire = 31
  7134  		}
  7135  	}
  7136  
  7137  	// Emit basic blocks
  7138  	for i, b := range f.Blocks {
  7139  
  7140  		s.lineRunStart = nil
  7141  		s.SetPos(s.pp.Pos.WithNotStmt()) // It needs a non-empty Pos, but cannot be a statement boundary (yet).
  7142  
  7143  		if hotAlign > 0 && b.Hotness&ssa.HotPgoInitial == ssa.HotPgoInitial {
  7144  			// So far this has only been shown profitable for PGO-hot loop headers.
  7145  			// The Hotness values allows distinctions between initial blocks that are "hot" or not, and "flow-in" or not.
  7146  			// Currently only the initial blocks of loops are tagged in this way;
  7147  			// there are no blocks tagged "pgo-hot" that are not also tagged "initial".
  7148  			// TODO more heuristics, more architectures.
  7149  			p := s.pp.Prog(obj.APCALIGNMAX)
  7150  			p.From.SetConst(hotAlign)
  7151  			p.To.SetConst(hotRequire)
  7152  		}
  7153  
  7154  		s.bstart[b.ID] = s.pp.Next
  7155  
  7156  		if idx, ok := argLiveBlockMap[b.ID]; ok && idx != argLiveIdx {
  7157  			argLiveIdx = idx
  7158  			p := s.pp.Prog(obj.APCDATA)
  7159  			p.From.SetConst(rtabi.PCDATA_ArgLiveIndex)
  7160  			p.To.SetConst(int64(idx))
  7161  		}
  7162  
  7163  		// Emit values in block
  7164  		Arch.SSAMarkMoves(&s, b)
  7165  		for _, v := range b.Values {
  7166  			x := s.pp.Next
  7167  			s.DebugFriendlySetPosFrom(v)
  7168  
  7169  			if v.Op.ResultInArg0() && v.ResultReg() != v.Args[0].Reg() {
  7170  				v.Fatalf("input[0] and output not in same register %s", v.LongString())
  7171  			}
  7172  
  7173  			switch v.Op {
  7174  			case ssaop.OpInitMem:
  7175  				// memory arg needs no code
  7176  			case ssaop.OpArg:
  7177  				// input args need no code
  7178  			case ssaop.OpSP, ssaop.OpSB:
  7179  				// nothing to do
  7180  			case ssaop.OpSelect0, ssaop.OpSelect1, ssaop.OpSelectN, ssaop.OpMakeResult:
  7181  				// nothing to do
  7182  			case ssaop.OpGetG:
  7183  				// nothing to do when there's a g register,
  7184  				// and checkLower complains if there's not
  7185  			case ssaop.OpVarDef, ssaop.OpVarLive, ssaop.OpKeepAlive, ssaop.OpWBend:
  7186  				// nothing to do; already used by liveness
  7187  			case ssaop.OpPhi:
  7188  				CheckLoweredPhi(v)
  7189  			case ssaop.OpConvert:
  7190  				// nothing to do; no-op conversion for liveness
  7191  				if v.Args[0].Reg() != v.Reg() {
  7192  					v.Fatalf("OpConvert should be a no-op: %s; %s", v.Args[0].LongString(), v.LongString())
  7193  				}
  7194  			case ssaop.OpInlMark:
  7195  				p := Arch.Ginsnop(s.pp)
  7196  				if inlMarks == nil {
  7197  					inlMarks = map[*obj.Prog]int32{}
  7198  					inlMarksByPos = map[src.XPos][]*obj.Prog{}
  7199  				}
  7200  				inlMarks[p] = v.AuxInt32()
  7201  				inlMarkList = append(inlMarkList, p)
  7202  				pos := v.Pos.AtColumn1()
  7203  				inlMarksByPos[pos] = append(inlMarksByPos[pos], p)
  7204  				firstPos = src.NoXPos
  7205  
  7206  			default:
  7207  				// Special case for first line in function; move it to the start (which cannot be a register-valued instruction)
  7208  				if firstPos != src.NoXPos && v.Op != ssaop.OpArgIntReg && v.Op != ssaop.OpArgFloatReg && v.Op != ssaop.OpLoadReg && v.Op != ssaop.OpStoreReg {
  7209  					s.SetPos(firstPos)
  7210  					firstPos = src.NoXPos
  7211  				}
  7212  				// Attach this safe point to the next
  7213  				// instruction.
  7214  				s.pp.NextLive = s.livenessMap.Get(v)
  7215  				s.pp.NextUnsafe = s.livenessMap.GetUnsafe(v)
  7216  
  7217  				// let the backend handle it
  7218  				Arch.SSAGenValue(&s, v)
  7219  			}
  7220  
  7221  			if idx, ok := argLiveValueMap[v.ID]; ok && idx != argLiveIdx {
  7222  				argLiveIdx = idx
  7223  				p := s.pp.Prog(obj.APCDATA)
  7224  				p.From.SetConst(rtabi.PCDATA_ArgLiveIndex)
  7225  				p.To.SetConst(int64(idx))
  7226  			}
  7227  
  7228  			if base.Ctxt.Flag_locationlists {
  7229  				valueToProgAfter[v.ID] = s.pp.Next
  7230  			}
  7231  
  7232  			if gatherPrintInfo {
  7233  				for ; x != s.pp.Next; x = x.Link {
  7234  					progToValue[x] = v
  7235  				}
  7236  			}
  7237  		}
  7238  		// If this is an empty infinite loop, stick a hardware NOP in there so that debuggers are less confused.
  7239  		if s.bstart[b.ID] == s.pp.Next && len(b.Succs) == 1 && b.Succs[0].Block() == b {
  7240  			p := Arch.Ginsnop(s.pp)
  7241  			p.Pos = p.Pos.WithIsStmt()
  7242  			if b.Pos == src.NoXPos {
  7243  				b.Pos = p.Pos // It needs a file, otherwise a no-file non-zero line causes confusion.  See #35652.
  7244  				if b.Pos == src.NoXPos {
  7245  					b.Pos = s.pp.Text.Pos // Sometimes p.Pos is empty.  See #35695.
  7246  				}
  7247  			}
  7248  			b.Pos = b.Pos.WithBogusLine() // Debuggers are not good about infinite loops, force a change in line number
  7249  		}
  7250  
  7251  		// Set unsafe mark for any end-of-block generated instructions
  7252  		// (normally, conditional or unconditional branches).
  7253  		// This is particularly important for empty blocks, as there
  7254  		// are no values to inherit the unsafe mark from.
  7255  		s.pp.NextUnsafe = s.livenessMap.GetUnsafeBlock(b)
  7256  
  7257  		// Emit control flow instructions for block
  7258  		var next *ssa.Block
  7259  		if i < len(f.Blocks)-1 && base.Flag.N == 0 {
  7260  			// If -N, leave next==nil so every block with successors
  7261  			// ends in a JMP (except call blocks - plive doesn't like
  7262  			// select{send,recv} followed by a JMP call).  Helps keep
  7263  			// line numbers for otherwise empty blocks.
  7264  			next = f.Blocks[i+1]
  7265  		}
  7266  		x := s.pp.Next
  7267  		s.SetPos(b.Pos)
  7268  		Arch.SSAGenBlock(&s, b, next)
  7269  		if gatherPrintInfo {
  7270  			for ; x != s.pp.Next; x = x.Link {
  7271  				progToBlock[x] = b
  7272  			}
  7273  		}
  7274  	}
  7275  	if f.Blocks[len(f.Blocks)-1].Kind == block.BlockExit {
  7276  		// We need the return address of a panic call to
  7277  		// still be inside the function in question. So if
  7278  		// it ends in a call which doesn't return, add a
  7279  		// nop (which will never execute) after the call.
  7280  		Arch.Ginsnop(s.pp)
  7281  	}
  7282  	if openDeferInfo != nil {
  7283  		// When doing open-coded defers, generate a disconnected call to
  7284  		// deferreturn and a return. This will be used to during panic
  7285  		// recovery to unwind the stack and return back to the runtime.
  7286  
  7287  		// Note that this exit code doesn't work if a return parameter
  7288  		// is heap-allocated, but open defers aren't enabled in that case.
  7289  
  7290  		// TODO either make this handle heap-allocated return parameters or reuse the other-defers general-purpose code path.
  7291  		s.pp.NextLive = s.livenessMap.DeferReturn
  7292  		p := s.pp.Prog(obj.ACALL)
  7293  		p.To.Type = obj.TYPE_MEM
  7294  		p.To.Name = obj.NAME_EXTERN
  7295  		p.To.Sym = ir.Syms.Deferreturn
  7296  
  7297  		// Load results into registers. So when a deferred function
  7298  		// recovers a panic, it will return to caller with right results.
  7299  		// The results are already in memory, because they are not SSA'd
  7300  		// when the function has defers (see canSSAName).
  7301  		for _, o := range f.OwnAux.ABIInfo().OutParams() {
  7302  			n := o.Name
  7303  			rts, offs := o.RegisterTypesAndOffsets()
  7304  			for i := range o.Registers {
  7305  				Arch.LoadRegResult(&s, f, rts[i], ssa.ObjRegForAbiReg(o.Registers[i], f.Config), n, offs[i])
  7306  			}
  7307  		}
  7308  
  7309  		s.pp.Prog(obj.ARET)
  7310  	}
  7311  
  7312  	if inlMarks != nil {
  7313  		hasCall := false
  7314  
  7315  		// We have some inline marks. Try to find other instructions we're
  7316  		// going to emit anyway, and use those instructions instead of the
  7317  		// inline marks.
  7318  		for p := s.pp.Text; p != nil; p = p.Link {
  7319  			if p.As == obj.ANOP || p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT ||
  7320  				p.As == obj.APCALIGN || p.As == obj.APCALIGNMAX || Arch.LinkArch.Family == sys.Wasm {
  7321  				// Don't use 0-sized instructions as inline marks, because we need
  7322  				// to identify inline mark instructions by pc offset.
  7323  				// (Some of these instructions are sometimes zero-sized, sometimes not.
  7324  				// We must not use anything that even might be zero-sized.)
  7325  				// TODO: are there others?
  7326  				continue
  7327  			}
  7328  			if _, ok := inlMarks[p]; ok {
  7329  				// Don't use inline marks themselves. We don't know
  7330  				// whether they will be zero-sized or not yet.
  7331  				continue
  7332  			}
  7333  			if p.As == obj.ACALL || p.As == obj.ADUFFCOPY || p.As == obj.ADUFFZERO {
  7334  				hasCall = true
  7335  			}
  7336  			pos := p.Pos.AtColumn1()
  7337  			marks := inlMarksByPos[pos]
  7338  			if len(marks) == 0 {
  7339  				continue
  7340  			}
  7341  			for _, m := range marks {
  7342  				// We found an instruction with the same source position as
  7343  				// some of the inline marks.
  7344  				// Use this instruction instead.
  7345  				p.Pos = p.Pos.WithIsStmt() // promote position to a statement
  7346  				s.pp.CurFunc.LSym.Func().AddInlMark(p, inlMarks[m])
  7347  				// Make the inline mark a real nop, so it doesn't generate any code.
  7348  				m.As = obj.ANOP
  7349  				m.Pos = src.NoXPos
  7350  				m.From = obj.Addr{}
  7351  				m.To = obj.Addr{}
  7352  			}
  7353  			delete(inlMarksByPos, pos)
  7354  		}
  7355  		// Any unmatched inline marks now need to be added to the inlining tree (and will generate a nop instruction).
  7356  		for _, p := range inlMarkList {
  7357  			if p.As != obj.ANOP {
  7358  				s.pp.CurFunc.LSym.Func().AddInlMark(p, inlMarks[p])
  7359  			}
  7360  		}
  7361  
  7362  		if e.stksize == 0 && !hasCall {
  7363  			// Frameless leaf function. It doesn't need any preamble,
  7364  			// so make sure its first instruction isn't from an inlined callee.
  7365  			// If it is, add a nop at the start of the function with a position
  7366  			// equal to the start of the function.
  7367  			// This ensures that runtime.FuncForPC(uintptr(reflect.ValueOf(fn).Pointer())).Name()
  7368  			// returns the right answer. See issue 58300.
  7369  			for p := s.pp.Text; p != nil; p = p.Link {
  7370  				if p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT || p.As == obj.ANOP {
  7371  					continue
  7372  				}
  7373  				if base.Ctxt.PosTable.Pos(p.Pos).Base().InliningIndex() >= 0 {
  7374  					// Make a real (not 0-sized) nop.
  7375  					nop := Arch.Ginsnop(s.pp)
  7376  					nop.Pos = e.curfn.Pos().WithIsStmt()
  7377  
  7378  					// Unfortunately, Ginsnop puts the instruction at the
  7379  					// end of the list. Move it up to just before p.
  7380  
  7381  					// Unlink from the current list.
  7382  					for x := s.pp.Text; x != nil; x = x.Link {
  7383  						if x.Link == nop {
  7384  							x.Link = nop.Link
  7385  							break
  7386  						}
  7387  					}
  7388  					// Splice in right before p.
  7389  					for x := s.pp.Text; x != nil; x = x.Link {
  7390  						if x.Link == p {
  7391  							nop.Link = p
  7392  							x.Link = nop
  7393  							break
  7394  						}
  7395  					}
  7396  				}
  7397  				break
  7398  			}
  7399  		}
  7400  	}
  7401  
  7402  	if base.Ctxt.Flag_locationlists {
  7403  		var debugInfo *ssadebug.FuncDebug
  7404  		debugInfo = e.curfn.DebugInfo.(*ssadebug.FuncDebug)
  7405  		// Save off entry ID in case we need it later for DWARF generation
  7406  		// for return values promoted to the heap.
  7407  		debugInfo.EntryID = f.Entry.ID
  7408  		if e.curfn.ABI == obj.ABIInternal && base.Flag.N != 0 {
  7409  			ssadebug.BuildFuncDebugNoOptimized(base.Ctxt, f, base.Debug.LocationLists > 1, StackOffset, debugInfo)
  7410  		} else {
  7411  			ssadebug.BuildFuncDebug(base.Ctxt, f, base.Debug.LocationLists, StackOffset, debugInfo)
  7412  		}
  7413  		bstart := s.bstart
  7414  		idToIdx := make([]int, f.NumBlocks())
  7415  		for i, b := range f.Blocks {
  7416  			idToIdx[b.ID] = i
  7417  		}
  7418  		// Register a callback that will be used later to fill in PCs into location
  7419  		// lists. At the moment, Prog.Pc is a sequence number; it's not a real PC
  7420  		// until after assembly, so the translation needs to be deferred.
  7421  		debugInfo.GetPC = func(b, v ssa.ID) int64 {
  7422  			switch v {
  7423  			case ssa.BlockStart.ID:
  7424  				if b == f.Entry.ID {
  7425  					return 0 // Start at the very beginning, at the assembler-generated prologue.
  7426  					// this should only happen for function args (ssa.OpArg)
  7427  				}
  7428  				return bstart[b].Pc
  7429  			case ssa.BlockEnd.ID:
  7430  				blk := f.Blocks[idToIdx[b]]
  7431  				nv := len(blk.Values)
  7432  				return valueToProgAfter[blk.Values[nv-1].ID].Pc
  7433  			case ssa.FuncEnd.ID:
  7434  				return e.curfn.LSym.Size
  7435  			default:
  7436  				return valueToProgAfter[v].Pc
  7437  			}
  7438  		}
  7439  	}
  7440  
  7441  	// Resolve branches, and relax DefaultStmt into NotStmt
  7442  	for _, br := range s.Branches {
  7443  		br.P.To.SetTarget(s.bstart[br.B.ID])
  7444  		if br.P.Pos.IsStmt() != src.PosIsStmt {
  7445  			br.P.Pos = br.P.Pos.WithNotStmt()
  7446  		} else if v0 := br.B.FirstPossibleStmtValue(); v0 != nil && v0.Pos.Line() == br.P.Pos.Line() && v0.Pos.IsStmt() == src.PosIsStmt {
  7447  			br.P.Pos = br.P.Pos.WithNotStmt()
  7448  		}
  7449  
  7450  	}
  7451  
  7452  	// Resolve jump table destinations.
  7453  	for _, jt := range s.JumpTables {
  7454  		// Convert from *Block targets to *Prog targets.
  7455  		targets := make([]*obj.Prog, len(jt.Succs))
  7456  		for i, e := range jt.Succs {
  7457  			targets[i] = s.bstart[e.Block().ID]
  7458  		}
  7459  		// Add to list of jump tables to be resolved at assembly time.
  7460  		// The assembler converts from *Prog entries to absolute addresses
  7461  		// once it knows instruction byte offsets.
  7462  		fi := s.pp.CurFunc.LSym.Func()
  7463  		fi.JumpTables = append(fi.JumpTables, obj.JumpTable{Sym: jt.Aux.(*obj.LSym), Targets: targets})
  7464  	}
  7465  
  7466  	// Finalize the frame, then let the backend run a final pass over the
  7467  	// generated Progs (e.g. arm64 fuses adjacent spill/reload MOVDs into
  7468  	// STP/LDP). Branch and jump-table targets are resolved at this point.
  7469  	// Doing this before the debug dumps below means -S and GOSSAFUNC's genssa
  7470  	// output reflect the instructions that are actually assembled. defframe
  7471  	// must run first: it finalizes the frame size, which the backend pass
  7472  	// depends on.
  7473  	defframe(&s, e, f)
  7474  	if Arch.SSAGenFinish != nil {
  7475  		Arch.SSAGenFinish(s.pp)
  7476  	}
  7477  
  7478  	if e.log { // spew to stdout
  7479  		filename := ""
  7480  		for p := s.pp.Text; p != nil; p = p.Link {
  7481  			if p.Pos.IsKnown() && p.InnermostFilename() != filename {
  7482  				filename = p.InnermostFilename()
  7483  				f.Logf("# %s\n", filename)
  7484  			}
  7485  
  7486  			var s string
  7487  			if v, ok := progToValue[p]; ok {
  7488  				s = v.String()
  7489  			} else if b, ok := progToBlock[p]; ok {
  7490  				s = b.String()
  7491  			} else {
  7492  				s = "   " // most value and branch strings are 2-3 characters long
  7493  			}
  7494  			f.Logf(" %-6s\t%.5d (%s)\t%s\n", s, p.Pc, p.InnermostLineNumber(), p.InstructionString())
  7495  		}
  7496  	}
  7497  	if htmlWriter.Enabled() { // spew to ssa.html
  7498  		var buf strings.Builder
  7499  		buf.WriteString("<code>")
  7500  		buf.WriteString("<dl class=\"ssa-gen\">")
  7501  		filename := ""
  7502  
  7503  		liveness := lv.Format(nil)
  7504  		if liveness != "" {
  7505  			buf.WriteString("<dt class=\"ssa-prog-src\"></dt><dd class=\"ssa-prog\">")
  7506  			buf.WriteString(html.EscapeString("# " + liveness))
  7507  			buf.WriteString("</dd>")
  7508  		}
  7509  
  7510  		for p := s.pp.Text; p != nil; p = p.Link {
  7511  			// Don't spam every line with the file name, which is often huge.
  7512  			// Only print changes, and "unknown" is not a change.
  7513  			if p.Pos.IsKnown() && p.InnermostFilename() != filename {
  7514  				filename = p.InnermostFilename()
  7515  				buf.WriteString("<dt class=\"ssa-prog-src\"></dt><dd class=\"ssa-prog\">")
  7516  				buf.WriteString(html.EscapeString("# " + filename))
  7517  				buf.WriteString("</dd>")
  7518  			}
  7519  
  7520  			buf.WriteString("<dt class=\"ssa-prog-src\">")
  7521  			if v, ok := progToValue[p]; ok {
  7522  
  7523  				// Prefix calls with their liveness, if any
  7524  				if p.As != obj.APCDATA {
  7525  					if liveness := lv.Format(v); liveness != "" {
  7526  						// Steal this line, and restart a line
  7527  						buf.WriteString("</dt><dd class=\"ssa-prog\">")
  7528  						buf.WriteString(html.EscapeString("# " + liveness))
  7529  						buf.WriteString("</dd>")
  7530  						// restarting a line
  7531  						buf.WriteString("<dt class=\"ssa-prog-src\">")
  7532  					}
  7533  				}
  7534  
  7535  				buf.WriteString(v.HTML())
  7536  			} else if b, ok := progToBlock[p]; ok {
  7537  				buf.WriteString("<b>" + b.HTML() + "</b>")
  7538  			}
  7539  			buf.WriteString("</dt>")
  7540  			buf.WriteString("<dd class=\"ssa-prog\">")
  7541  			fmt.Fprintf(&buf, "%.5d <span class=\"l%v line-number\">(%s)</span> %s", p.Pc, p.InnermostLineNumber(), p.InnermostLineNumberHTML(), html.EscapeString(p.InstructionString()))
  7542  			buf.WriteString("</dd>")
  7543  		}
  7544  		buf.WriteString("</dl>")
  7545  		buf.WriteString("</code>")
  7546  		htmlWriter.WriteColumn("genssa", "genssa", "ssa-prog", buf.String())
  7547  	}
  7548  	if ssaconfig.GenssaDump[f.Name] {
  7549  		fi := f.DumpFileForPhase("genssa")
  7550  		if fi != nil {
  7551  
  7552  			// inliningDiffers if any filename changes or if any line number except the innermost (last index) changes.
  7553  			inliningDiffers := func(a, b []src.Pos) bool {
  7554  				if len(a) != len(b) {
  7555  					return true
  7556  				}
  7557  				for i := range a {
  7558  					if a[i].Filename() != b[i].Filename() {
  7559  						return true
  7560  					}
  7561  					if i != len(a)-1 && a[i].Line() != b[i].Line() {
  7562  						return true
  7563  					}
  7564  				}
  7565  				return false
  7566  			}
  7567  
  7568  			var allPosOld []src.Pos
  7569  			var allPos []src.Pos
  7570  
  7571  			for p := s.pp.Text; p != nil; p = p.Link {
  7572  				if p.Pos.IsKnown() {
  7573  					allPos = allPos[:0]
  7574  					p.Ctxt.AllPos(p.Pos, func(pos src.Pos) { allPos = append(allPos, pos) })
  7575  					if inliningDiffers(allPos, allPosOld) {
  7576  						for _, pos := range allPos {
  7577  							fmt.Fprintf(fi, "# %s:%d\n", pos.Filename(), pos.Line())
  7578  						}
  7579  						allPos, allPosOld = allPosOld, allPos // swap, not copy, so that they do not share slice storage.
  7580  					}
  7581  				}
  7582  
  7583  				var s string
  7584  				if v, ok := progToValue[p]; ok {
  7585  					s = v.String()
  7586  				} else if b, ok := progToBlock[p]; ok {
  7587  					s = b.String()
  7588  				} else {
  7589  					s = "   " // most value and branch strings are 2-3 characters long
  7590  				}
  7591  				fmt.Fprintf(fi, " %-6s\t%.5d %s\t%s\n", s, p.Pc, ssa.StmtString(p.Pos), p.InstructionString())
  7592  			}
  7593  			fi.Close()
  7594  		}
  7595  	}
  7596  
  7597  	htmlWriter.Close()
  7598  	htmlWriter = nil
  7599  }
  7600  
  7601  func defframe(s *State, e *ssafn, f *ssa.Func) {
  7602  	pp := s.pp
  7603  
  7604  	s.maxarg = types.RoundUp(s.maxarg, e.stkalign)
  7605  	frame := s.maxarg + e.stksize
  7606  	if Arch.PadFrame != nil {
  7607  		frame = Arch.PadFrame(frame)
  7608  	}
  7609  
  7610  	// Fill in argument and frame size.
  7611  	pp.Text.To.Type = obj.TYPE_TEXTSIZE
  7612  	pp.Text.To.Val = int32(types.RoundUp(f.OwnAux.ArgWidth(), int64(types.RegSize)))
  7613  	pp.Text.To.Offset = frame
  7614  
  7615  	p := pp.Text
  7616  
  7617  	// Insert code to spill argument registers if the named slot may be partially
  7618  	// live. That is, the named slot is considered live by liveness analysis,
  7619  	// (because a part of it is live), but we may not spill all parts into the
  7620  	// slot. This can only happen with aggregate-typed arguments that are SSA-able
  7621  	// and not address-taken (for non-SSA-able or address-taken arguments we always
  7622  	// spill upfront).
  7623  	// Note: spilling is unnecessary in the -N/no-optimize case, since all values
  7624  	// will be considered non-SSAable and spilled up front.
  7625  	// TODO(register args) Make liveness more fine-grained to that partial spilling is okay.
  7626  	if f.OwnAux.ABIInfo().InRegistersUsed() != 0 && base.Flag.N == 0 {
  7627  		// First, see if it is already spilled before it may be live. Look for a spill
  7628  		// in the entry block up to the first safepoint.
  7629  		type nameOff struct {
  7630  			n   *ir.Name
  7631  			off int64
  7632  		}
  7633  		partLiveArgsSpilled := make(map[nameOff]bool)
  7634  		for _, v := range f.Entry.Values {
  7635  			if v.Op.IsCall() {
  7636  				break
  7637  			}
  7638  			if v.Op != ssaop.OpStoreReg || v.Args[0].Op != ssaop.OpArgIntReg {
  7639  				continue
  7640  			}
  7641  			n, off := ssa.AutoVar(v)
  7642  			if n.Class != ir.PPARAM || n.Addrtaken() || !ssa.CanSSA(n.Type()) || !s.partLiveArgs[n] {
  7643  				continue
  7644  			}
  7645  			partLiveArgsSpilled[nameOff{n, off}] = true
  7646  		}
  7647  
  7648  		// Then, insert code to spill registers if not already.
  7649  		for _, a := range f.OwnAux.ABIInfo().InParams() {
  7650  			n := a.Name
  7651  			if n == nil || n.Addrtaken() || !ssa.CanSSA(n.Type()) || !s.partLiveArgs[n] || len(a.Registers) <= 1 {
  7652  				continue
  7653  			}
  7654  			rts, offs := a.RegisterTypesAndOffsets()
  7655  			for i := range a.Registers {
  7656  				if !rts[i].HasPointers() {
  7657  					continue
  7658  				}
  7659  				if partLiveArgsSpilled[nameOff{n, offs[i]}] {
  7660  					continue // already spilled
  7661  				}
  7662  				reg := ssa.ObjRegForAbiReg(a.Registers[i], f.Config)
  7663  				p = Arch.SpillArgReg(pp, p, f, rts[i], reg, n, offs[i])
  7664  			}
  7665  		}
  7666  	}
  7667  
  7668  	// Insert code to zero ambiguously live variables so that the
  7669  	// garbage collector only sees initialized values when it
  7670  	// looks for pointers.
  7671  	var lo, hi int64
  7672  
  7673  	// Opaque state for backend to use. Current backends use it to
  7674  	// keep track of which helper registers have been zeroed.
  7675  	var state uint32
  7676  
  7677  	// Iterate through declarations. Autos are sorted in decreasing
  7678  	// frame offset order.
  7679  	for _, n := range e.curfn.Dcl {
  7680  		if !n.Needzero() {
  7681  			continue
  7682  		}
  7683  		if n.Class != ir.PAUTO {
  7684  			e.Fatalf(n.Pos(), "needzero class %d", n.Class)
  7685  		}
  7686  		if n.Type().Size()%int64(types.PtrSize) != 0 || n.FrameOffset()%int64(types.PtrSize) != 0 || n.Type().Size() == 0 {
  7687  			e.Fatalf(n.Pos(), "var %L has size %d offset %d", n, n.Type().Size(), n.Offset_)
  7688  		}
  7689  
  7690  		if lo != hi && n.FrameOffset()+n.Type().Size() >= lo-int64(2*types.RegSize) {
  7691  			// Merge with range we already have.
  7692  			lo = n.FrameOffset()
  7693  			continue
  7694  		}
  7695  
  7696  		// Zero old range
  7697  		p = Arch.ZeroRange(pp, p, frame+lo, hi-lo, &state)
  7698  
  7699  		// Set new range.
  7700  		lo = n.FrameOffset()
  7701  		hi = lo + n.Type().Size()
  7702  	}
  7703  
  7704  	// Zero final range.
  7705  	Arch.ZeroRange(pp, p, frame+lo, hi-lo, &state)
  7706  }
  7707  
  7708  // For generating consecutive jump instructions to model a specific branching
  7709  type IndexJump struct {
  7710  	Jump  obj.As
  7711  	Index int
  7712  }
  7713  
  7714  func (s *State) oneJump(b *ssa.Block, jump *IndexJump) {
  7715  	p := s.Br(jump.Jump, b.Succs[jump.Index].Block())
  7716  	p.Pos = b.Pos
  7717  }
  7718  
  7719  // CombJump generates combinational instructions (2 at present) for a block jump,
  7720  // thereby the behaviour of non-standard condition codes could be simulated
  7721  func (s *State) CombJump(b, next *ssa.Block, jumps *[2][2]IndexJump) {
  7722  	switch next {
  7723  	case b.Succs[0].Block():
  7724  		s.oneJump(b, &jumps[0][0])
  7725  		s.oneJump(b, &jumps[0][1])
  7726  	case b.Succs[1].Block():
  7727  		s.oneJump(b, &jumps[1][0])
  7728  		s.oneJump(b, &jumps[1][1])
  7729  	default:
  7730  		var q *obj.Prog
  7731  		if b.Likely != ssa.BranchUnlikely {
  7732  			s.oneJump(b, &jumps[1][0])
  7733  			s.oneJump(b, &jumps[1][1])
  7734  			q = s.Br(obj.AJMP, b.Succs[1].Block())
  7735  		} else {
  7736  			s.oneJump(b, &jumps[0][0])
  7737  			s.oneJump(b, &jumps[0][1])
  7738  			q = s.Br(obj.AJMP, b.Succs[0].Block())
  7739  		}
  7740  		q.Pos = b.Pos
  7741  	}
  7742  }
  7743  
  7744  // AddAux adds the offset in the aux fields (AuxInt and Aux) of v to a.
  7745  func AddAux(a *obj.Addr, v *ssa.Value) {
  7746  	AddAux2(a, v, v.AuxInt)
  7747  }
  7748  func AddAux2(a *obj.Addr, v *ssa.Value, offset int64) {
  7749  	if a.Type != obj.TYPE_MEM && a.Type != obj.TYPE_ADDR {
  7750  		v.Fatalf("bad AddAux addr %v", a)
  7751  	}
  7752  	// add integer offset
  7753  	a.Offset += offset
  7754  
  7755  	// If no additional symbol offset, we're done.
  7756  	if v.Aux == nil {
  7757  		return
  7758  	}
  7759  	// Add symbol's offset from its base register.
  7760  	switch n := v.Aux.(type) {
  7761  	case *ssa.AuxCall:
  7762  		a.Name = obj.NAME_EXTERN
  7763  		a.Sym = n.Fn
  7764  	case *obj.LSym:
  7765  		a.Name = obj.NAME_EXTERN
  7766  		a.Sym = n
  7767  	case *ir.Name:
  7768  		if n.Class == ir.PPARAM || (n.Class == ir.PPARAMOUT && !n.IsOutputParamInRegisters()) {
  7769  			a.Name = obj.NAME_PARAM
  7770  		} else {
  7771  			a.Name = obj.NAME_AUTO
  7772  		}
  7773  		a.Sym = n.Linksym()
  7774  		a.Offset += n.FrameOffset()
  7775  	default:
  7776  		v.Fatalf("aux in %s not implemented %#v", v, v.Aux)
  7777  	}
  7778  }
  7779  
  7780  // extendIndex extends v to a full int width.
  7781  // panic with the given kind if v does not fit in an int (only on 32-bit archs).
  7782  func (s *state) extendIndex(idx, len *ssa.Value, kind ssa.BoundsKind, bounded bool) *ssa.Value {
  7783  	size := idx.Type.Size()
  7784  	if size == s.config.PtrSize {
  7785  		return idx
  7786  	}
  7787  	if size > s.config.PtrSize {
  7788  		// truncate 64-bit indexes on 32-bit pointer archs. Test the
  7789  		// high word and branch to out-of-bounds failure if it is not 0.
  7790  		var lo *ssa.Value
  7791  		if idx.Type.IsSigned() {
  7792  			lo = s.newValue1(ssaop.OpInt64Lo, types.Types[types.TINT], idx)
  7793  		} else {
  7794  			lo = s.newValue1(ssaop.OpInt64Lo, types.Types[types.TUINT], idx)
  7795  		}
  7796  		if bounded || base.Flag.B != 0 {
  7797  			return lo
  7798  		}
  7799  		bNext := s.f.NewBlock(block.BlockPlain)
  7800  		bPanic := s.f.NewBlock(block.BlockExit)
  7801  		hi := s.newValue1(ssaop.OpInt64Hi, types.Types[types.TUINT32], idx)
  7802  		cmp := s.newValue2(ssaop.OpEq32, types.Types[types.TBOOL], hi, s.constInt32(types.Types[types.TUINT32], 0))
  7803  		if !idx.Type.IsSigned() {
  7804  			switch kind {
  7805  			case ssa.BoundsIndex:
  7806  				kind = ssa.BoundsIndexU
  7807  			case ssa.BoundsSliceAlen:
  7808  				kind = ssa.BoundsSliceAlenU
  7809  			case ssa.BoundsSliceAcap:
  7810  				kind = ssa.BoundsSliceAcapU
  7811  			case ssa.BoundsSliceB:
  7812  				kind = ssa.BoundsSliceBU
  7813  			case ssa.BoundsSlice3Alen:
  7814  				kind = ssa.BoundsSlice3AlenU
  7815  			case ssa.BoundsSlice3Acap:
  7816  				kind = ssa.BoundsSlice3AcapU
  7817  			case ssa.BoundsSlice3B:
  7818  				kind = ssa.BoundsSlice3BU
  7819  			case ssa.BoundsSlice3C:
  7820  				kind = ssa.BoundsSlice3CU
  7821  			}
  7822  		}
  7823  		b := s.endBlock()
  7824  		b.Kind = block.BlockIf
  7825  		b.SetControl(cmp)
  7826  		b.Likely = ssa.BranchLikely
  7827  		b.AddEdgeTo(bNext)
  7828  		b.AddEdgeTo(bPanic)
  7829  
  7830  		s.startBlock(bPanic)
  7831  		mem := s.newValue4I(ssaop.OpPanicExtend, types.TypeMem, int64(kind), hi, lo, len, s.mem())
  7832  		s.endBlock().SetControl(mem)
  7833  		s.startBlock(bNext)
  7834  
  7835  		return lo
  7836  	}
  7837  
  7838  	// Extend value to the required size
  7839  	var op ssaop.Op
  7840  	if idx.Type.IsSigned() {
  7841  		switch 10*size + s.config.PtrSize {
  7842  		case 14:
  7843  			op = ssaop.OpSignExt8to32
  7844  		case 18:
  7845  			op = ssaop.OpSignExt8to64
  7846  		case 24:
  7847  			op = ssaop.OpSignExt16to32
  7848  		case 28:
  7849  			op = ssaop.OpSignExt16to64
  7850  		case 48:
  7851  			op = ssaop.OpSignExt32to64
  7852  		default:
  7853  			s.Fatalf("bad signed index extension %s", idx.Type)
  7854  		}
  7855  	} else {
  7856  		switch 10*size + s.config.PtrSize {
  7857  		case 14:
  7858  			op = ssaop.OpZeroExt8to32
  7859  		case 18:
  7860  			op = ssaop.OpZeroExt8to64
  7861  		case 24:
  7862  			op = ssaop.OpZeroExt16to32
  7863  		case 28:
  7864  			op = ssaop.OpZeroExt16to64
  7865  		case 48:
  7866  			op = ssaop.OpZeroExt32to64
  7867  		default:
  7868  			s.Fatalf("bad unsigned index extension %s", idx.Type)
  7869  		}
  7870  	}
  7871  	return s.newValue1(op, types.Types[types.TINT], idx)
  7872  }
  7873  
  7874  // CheckLoweredPhi checks that regalloc and stackalloc correctly handled phi values.
  7875  // Called during ssaGenValue.
  7876  func CheckLoweredPhi(v *ssa.Value) {
  7877  	if v.Op != ssaop.OpPhi {
  7878  		v.Fatalf("CheckLoweredPhi called with non-phi value: %v", v.LongString())
  7879  	}
  7880  	if v.Type.IsMemory() {
  7881  		return
  7882  	}
  7883  	f := v.Block.Func
  7884  	loc := f.RegAlloc[v.ID]
  7885  	for _, a := range v.Args {
  7886  		if aloc := f.RegAlloc[a.ID]; aloc != loc { // TODO: .Equal() instead?
  7887  			v.Fatalf("phi arg at different location than phi: %v @ %s, but arg %v @ %s\n%s\n", v, loc, a, aloc, v.Block.Func)
  7888  		}
  7889  	}
  7890  }
  7891  
  7892  // CheckLoweredGetClosurePtr checks that v is the first instruction in the function's entry block,
  7893  // except for incoming in-register arguments.
  7894  // The output of LoweredGetClosurePtr is generally hardwired to the correct register.
  7895  // That register contains the closure pointer on closure entry.
  7896  func CheckLoweredGetClosurePtr(v *ssa.Value) {
  7897  	entry := v.Block.Func.Entry
  7898  	if entry != v.Block {
  7899  		base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
  7900  	}
  7901  	for _, w := range entry.Values {
  7902  		if w == v {
  7903  			break
  7904  		}
  7905  		switch w.Op {
  7906  		case ssaop.OpArgIntReg, ssaop.OpArgFloatReg:
  7907  			// okay
  7908  		default:
  7909  			base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
  7910  		}
  7911  	}
  7912  }
  7913  
  7914  // CheckArgReg ensures that v is in the function's entry block.
  7915  func CheckArgReg(v *ssa.Value) {
  7916  	entry := v.Block.Func.Entry
  7917  	if entry != v.Block {
  7918  		base.Fatalf("in %s, badly placed ArgIReg or ArgFReg: %v %v", v.Block.Func.Name, v.Block, v)
  7919  	}
  7920  }
  7921  
  7922  func AddrAuto(a *obj.Addr, v *ssa.Value) {
  7923  	n, off := ssa.AutoVar(v)
  7924  	a.Type = obj.TYPE_MEM
  7925  	a.Sym = n.Linksym()
  7926  	a.Reg = int16(Arch.REGSP)
  7927  	a.Offset = n.FrameOffset() + off
  7928  	if n.Class == ir.PPARAM || (n.Class == ir.PPARAMOUT && !n.IsOutputParamInRegisters()) {
  7929  		a.Name = obj.NAME_PARAM
  7930  	} else {
  7931  		a.Name = obj.NAME_AUTO
  7932  	}
  7933  }
  7934  
  7935  // Call returns a new CALL instruction for the SSA value v.
  7936  // It uses PrepareCall to prepare the call.
  7937  func (s *State) Call(v *ssa.Value) *obj.Prog {
  7938  	pPosIsStmt := s.pp.Pos.IsStmt() // The statement-ness of the call comes from ssaGenState
  7939  	s.PrepareCall(v)
  7940  
  7941  	p := s.Prog(obj.ACALL)
  7942  	if pPosIsStmt == src.PosIsStmt {
  7943  		p.Pos = v.Pos.WithIsStmt()
  7944  	} else {
  7945  		p.Pos = v.Pos.WithNotStmt()
  7946  	}
  7947  	if sym, ok := v.Aux.(*ssa.AuxCall); ok && sym.Fn != nil {
  7948  		p.To.Type = obj.TYPE_MEM
  7949  		p.To.Name = obj.NAME_EXTERN
  7950  		p.To.Sym = sym.Fn
  7951  	} else {
  7952  		// TODO(mdempsky): Can these differences be eliminated?
  7953  		switch Arch.LinkArch.Family {
  7954  		case sys.AMD64, sys.I386, sys.PPC64, sys.RISCV64, sys.S390X, sys.Wasm:
  7955  			p.To.Type = obj.TYPE_REG
  7956  		case sys.ARM, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64:
  7957  			p.To.Type = obj.TYPE_MEM
  7958  		default:
  7959  			base.Fatalf("unknown indirect call family")
  7960  		}
  7961  		p.To.Reg = v.Args[0].Reg()
  7962  	}
  7963  	return p
  7964  }
  7965  
  7966  // TailCall returns a new tail call instruction for the SSA value v.
  7967  // It is like Call, but for a tail call.
  7968  func (s *State) TailCall(v *ssa.Value) *obj.Prog {
  7969  	p := s.Call(v)
  7970  	p.As = obj.ARET
  7971  	return p
  7972  }
  7973  
  7974  // PrepareCall prepares to emit a CALL instruction for v and does call-related bookkeeping.
  7975  // It must be called immediately before emitting the actual CALL instruction,
  7976  // since it emits PCDATA for the stack map at the call (calls are safe points).
  7977  func (s *State) PrepareCall(v *ssa.Value) {
  7978  	idx := s.livenessMap.Get(v)
  7979  	if !idx.StackMapValid() {
  7980  		// See Liveness.hasStackMap.
  7981  		if sym, ok := v.Aux.(*ssa.AuxCall); !ok || !(sym.Fn == ir.Syms.WBZero || sym.Fn == ir.Syms.WBMove) {
  7982  			base.Fatalf("missing stack map index for %v", v.LongString())
  7983  		}
  7984  	}
  7985  
  7986  	call, ok := v.Aux.(*ssa.AuxCall)
  7987  
  7988  	if ok {
  7989  		// Record call graph information for nowritebarrierrec
  7990  		// analysis.
  7991  		if nowritebarrierrecCheck != nil {
  7992  			nowritebarrierrecCheck.recordCall(s.pp.CurFunc, call.Fn, v.Pos)
  7993  		}
  7994  	}
  7995  
  7996  	if s.maxarg < v.AuxInt {
  7997  		s.maxarg = v.AuxInt
  7998  	}
  7999  }
  8000  
  8001  // UseArgs records the fact that an instruction needs a certain amount of
  8002  // callee args space for its use.
  8003  func (s *State) UseArgs(n int64) {
  8004  	if s.maxarg < n {
  8005  		s.maxarg = n
  8006  	}
  8007  }
  8008  
  8009  // fieldIdx finds the index of the field referred to by the ODOT node n.
  8010  func fieldIdx(n *ir.SelectorExpr) int {
  8011  	t := n.X.Type()
  8012  	if !isStructNotSIMD(t) {
  8013  		panic("ODOT's LHS is not a struct")
  8014  	}
  8015  
  8016  	for i, f := range t.Fields() {
  8017  		if f.Sym == n.Sel {
  8018  			if f.Offset != n.Offset() {
  8019  				panic("field offset doesn't match")
  8020  			}
  8021  			return i
  8022  		}
  8023  	}
  8024  	panic(fmt.Sprintf("can't find field in expr %v\n", n))
  8025  
  8026  	// TODO: keep the result of this function somewhere in the ODOT Node
  8027  	// so we don't have to recompute it each time we need it.
  8028  }
  8029  
  8030  // ssafn holds frontend information about a function that the backend is processing.
  8031  // It also exports a bunch of compiler services for the ssa backend.
  8032  type ssafn struct {
  8033  	curfn      *ir.Func
  8034  	strings    map[string]*obj.LSym // map from constant string to data symbols
  8035  	stksize    int64                // stack size for current frame
  8036  	stkptrsize int64                // prefix of stack containing pointers
  8037  
  8038  	// alignment for current frame.
  8039  	// NOTE: when stkalign > PtrSize, currently this only ensures the offsets of
  8040  	// objects in the stack frame are aligned. The stack pointer is still aligned
  8041  	// only PtrSize.
  8042  	stkalign int64
  8043  
  8044  	log bool // print ssa debug to the stdout
  8045  }
  8046  
  8047  // StringData returns a symbol which
  8048  // is the data component of a global string constant containing s.
  8049  func (e *ssafn) StringData(s string) *obj.LSym {
  8050  	if aux, ok := e.strings[s]; ok {
  8051  		return aux
  8052  	}
  8053  	if e.strings == nil {
  8054  		e.strings = make(map[string]*obj.LSym)
  8055  	}
  8056  	data := staticdata.StringSym(e.curfn.Pos(), s)
  8057  	e.strings[s] = data
  8058  	return data
  8059  }
  8060  
  8061  // SplitSlot returns a slot representing the data of parent starting at offset.
  8062  func (e *ssafn) SplitSlot(parent *ssa.LocalSlot, suffix string, offset int64, t *types.Type) ssa.LocalSlot {
  8063  	node := parent.N
  8064  
  8065  	if node.Class != ir.PAUTO || node.Addrtaken() {
  8066  		// addressed things and non-autos retain their parents (i.e., cannot truly be split)
  8067  		return ssa.LocalSlot{N: node, Type: t, Off: parent.Off + offset}
  8068  	}
  8069  
  8070  	sym := &types.Sym{Name: node.Sym().Name + suffix, Pkg: types.LocalPkg}
  8071  	n := e.curfn.NewLocal(parent.N.Pos(), sym, t)
  8072  	n.SetUsed(true)
  8073  	n.SetEsc(ir.EscNever)
  8074  	types.CalcSize(t)
  8075  	return ssa.LocalSlot{N: n, Type: t, Off: 0, SplitOf: parent, SplitOffset: offset}
  8076  }
  8077  
  8078  // Logf logs a message from the compiler.
  8079  func (e *ssafn) Logf(msg string, args ...any) {
  8080  	if e.log {
  8081  		fmt.Printf(msg, args...)
  8082  	}
  8083  }
  8084  
  8085  func (e *ssafn) Log() bool {
  8086  	return e.log
  8087  }
  8088  
  8089  // Fatalf reports a compiler error and exits.
  8090  func (e *ssafn) Fatalf(pos src.XPos, msg string, args ...any) {
  8091  	base.Pos = pos
  8092  	nargs := append([]any{ir.FuncName(e.curfn)}, args...)
  8093  	base.Fatalf("'%s': "+msg, nargs...)
  8094  }
  8095  
  8096  // Warnl reports a "warning", which is usually flag-triggered
  8097  // logging output for the benefit of tests.
  8098  func (e *ssafn) Warnl(pos src.XPos, fmt_ string, args ...any) {
  8099  	base.WarnfAt(pos, fmt_, args...)
  8100  }
  8101  
  8102  func (e *ssafn) Debug_checknil() bool {
  8103  	return base.Debug.Nil != 0
  8104  }
  8105  
  8106  func (e *ssafn) UseWriteBarrier() bool {
  8107  	return base.Flag.WB
  8108  }
  8109  
  8110  func (e *ssafn) Syslook(name string) *obj.LSym {
  8111  	switch name {
  8112  	case "goschedguarded":
  8113  		return ir.Syms.Goschedguarded
  8114  	case "writeBarrier":
  8115  		return ir.Syms.WriteBarrier
  8116  	case "wbZero":
  8117  		return ir.Syms.WBZero
  8118  	case "wbMove":
  8119  		return ir.Syms.WBMove
  8120  	case "cgoCheckMemmove":
  8121  		return ir.Syms.CgoCheckMemmove
  8122  	case "cgoCheckPtrWrite":
  8123  		return ir.Syms.CgoCheckPtrWrite
  8124  	}
  8125  	e.Fatalf(src.NoXPos, "unknown Syslook func %v", name)
  8126  	return nil
  8127  }
  8128  
  8129  func (e *ssafn) Func() *ir.Func {
  8130  	return e.curfn
  8131  }
  8132  
  8133  func clobberBase(n ir.Node) ir.Node {
  8134  	if n.Op() == ir.ODOT {
  8135  		n := n.(*ir.SelectorExpr)
  8136  		if n.X.Type().NumFields() == 1 {
  8137  			return clobberBase(n.X)
  8138  		}
  8139  	}
  8140  	if n.Op() == ir.OINDEX {
  8141  		n := n.(*ir.IndexExpr)
  8142  		if n.X.Type().IsArray() && n.X.Type().NumElem() == 1 {
  8143  			return clobberBase(n.X)
  8144  		}
  8145  	}
  8146  	return n
  8147  }
  8148  
  8149  // callTargetLSym returns the correct LSym to call 'callee' using its ABI.
  8150  func callTargetLSym(callee *ir.Name) *obj.LSym {
  8151  	if callee.Func == nil {
  8152  		// TODO(austin): This happens in case of interface method I.M from imported package.
  8153  		// It's ABIInternal, and would be better if callee.Func was never nil and we didn't
  8154  		// need this case.
  8155  		return callee.Linksym()
  8156  	}
  8157  
  8158  	return callee.LinksymABI(callee.Func.ABI)
  8159  }
  8160  
  8161  // deferStructFnField is the field index of _defer.fn.
  8162  const deferStructFnField = 4
  8163  
  8164  var deferType *types.Type
  8165  
  8166  // deferstruct returns a type interchangeable with runtime._defer.
  8167  // Make sure this stays in sync with runtime/runtime2.go:_defer.
  8168  func deferstruct() *types.Type {
  8169  	if deferType != nil {
  8170  		return deferType
  8171  	}
  8172  
  8173  	makefield := func(name string, t *types.Type) *types.Field {
  8174  		sym := (*types.Pkg)(nil).Lookup(name)
  8175  		return types.NewField(src.NoXPos, sym, t)
  8176  	}
  8177  
  8178  	fields := []*types.Field{
  8179  		makefield("heap", types.Types[types.TBOOL]),
  8180  		makefield("rangefunc", types.Types[types.TBOOL]),
  8181  		makefield("sp", types.Types[types.TUINTPTR]),
  8182  		makefield("pc", types.Types[types.TUINTPTR]),
  8183  		// Note: the types here don't really matter. Defer structures
  8184  		// are always scanned explicitly during stack copying and GC,
  8185  		// so we make them uintptr type even though they are real pointers.
  8186  		makefield("fn", types.Types[types.TUINTPTR]),
  8187  		makefield("link", types.Types[types.TUINTPTR]),
  8188  		makefield("head", types.Types[types.TUINTPTR]),
  8189  	}
  8190  	if name := fields[deferStructFnField].Sym.Name; name != "fn" {
  8191  		base.Fatalf("deferStructFnField is %q, not fn", name)
  8192  	}
  8193  
  8194  	n := ir.NewDeclNameAt(src.NoXPos, ir.OTYPE, ir.Pkgs.Runtime.Lookup("_defer"))
  8195  	typ := types.NewNamed(n)
  8196  	n.SetType(typ)
  8197  	n.SetTypecheck(1)
  8198  
  8199  	// build struct holding the above fields
  8200  	typ.SetUnderlying(types.NewStruct(fields))
  8201  	types.CalcStructSize(typ)
  8202  
  8203  	deferType = typ
  8204  	return typ
  8205  }
  8206  
  8207  // SpillSlotAddr uses LocalSlot information to initialize an obj.Addr
  8208  // The resulting addr is used in a non-standard context -- in the prologue
  8209  // of a function, before the frame has been constructed, so the standard
  8210  // addressing for the parameters will be wrong.
  8211  func SpillSlotAddr(spill ssa.Spill, baseReg int16, extraOffset int64) obj.Addr {
  8212  	return obj.Addr{
  8213  		Name:   obj.NAME_NONE,
  8214  		Type:   obj.TYPE_MEM,
  8215  		Reg:    baseReg,
  8216  		Offset: spill.Offset + extraOffset,
  8217  	}
  8218  }
  8219  
  8220  func isStructNotSIMD(t *types.Type) bool {
  8221  	return t.IsStruct() && !t.IsSIMD()
  8222  }
  8223  
  8224  var BoundsCheckFunc [ssa.BoundsKindCount]*obj.LSym
  8225