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  	"os"
    16  	"path/filepath"
    17  	"slices"
    18  	"strings"
    19  
    20  	"cmd/compile/internal/abi"
    21  	"cmd/compile/internal/base"
    22  	"cmd/compile/internal/ir"
    23  	"cmd/compile/internal/liveness"
    24  	"cmd/compile/internal/objw"
    25  	"cmd/compile/internal/reflectdata"
    26  	"cmd/compile/internal/rttype"
    27  	"cmd/compile/internal/ssa"
    28  	"cmd/compile/internal/staticdata"
    29  	"cmd/compile/internal/typecheck"
    30  	"cmd/compile/internal/types"
    31  	"cmd/internal/obj"
    32  	"cmd/internal/objabi"
    33  	"cmd/internal/src"
    34  	"cmd/internal/sys"
    35  
    36  	rtabi "internal/abi"
    37  )
    38  
    39  var ssaConfig *ssa.Config
    40  var ssaCaches []ssa.Cache
    41  
    42  var ssaDump string     // early copy of $GOSSAFUNC; the func name to dump output for
    43  var ssaDir string      // optional destination for ssa dump file
    44  var ssaDumpStdout bool // whether to dump to stdout
    45  var ssaDumpCFG string  // generate CFGs for these phases
    46  const ssaDumpFile = "ssa.html"
    47  
    48  // ssaDumpInlined holds all inlined functions when ssaDump contains a function name.
    49  var ssaDumpInlined []*ir.Func
    50  
    51  // Maximum size we will aggregate heap allocations of scalar locals.
    52  // Almost certainly can't hurt to be as big as the tiny allocator.
    53  // Might help to be a bit bigger.
    54  const maxAggregatedHeapAllocation = 16
    55  
    56  func DumpInline(fn *ir.Func) {
    57  	if ssaDump != "" && ssaDump == ir.FuncName(fn) {
    58  		ssaDumpInlined = append(ssaDumpInlined, fn)
    59  	}
    60  }
    61  
    62  func InitEnv() {
    63  	ssaDump = os.Getenv("GOSSAFUNC")
    64  	ssaDir = os.Getenv("GOSSADIR")
    65  	if ssaDump != "" {
    66  		if strings.HasSuffix(ssaDump, "+") {
    67  			ssaDump = ssaDump[:len(ssaDump)-1]
    68  			ssaDumpStdout = true
    69  		}
    70  		spl := strings.Split(ssaDump, ":")
    71  		if len(spl) > 1 {
    72  			ssaDump = spl[0]
    73  			ssaDumpCFG = spl[1]
    74  		}
    75  	}
    76  }
    77  
    78  func InitConfig() {
    79  	types_ := ssa.NewTypes()
    80  
    81  	if Arch.SoftFloat {
    82  		softfloatInit()
    83  	}
    84  
    85  	// Generate a few pointer types that are uncommon in the frontend but common in the backend.
    86  	// Caching is disabled in the backend, so generating these here avoids allocations.
    87  	_ = types.NewPtr(types.Types[types.TINTER])                             // *interface{}
    88  	_ = types.NewPtr(types.NewPtr(types.Types[types.TSTRING]))              // **string
    89  	_ = types.NewPtr(types.NewSlice(types.Types[types.TINTER]))             // *[]interface{}
    90  	_ = types.NewPtr(types.NewPtr(types.ByteType))                          // **byte
    91  	_ = types.NewPtr(types.NewSlice(types.ByteType))                        // *[]byte
    92  	_ = types.NewPtr(types.NewSlice(types.Types[types.TSTRING]))            // *[]string
    93  	_ = types.NewPtr(types.NewPtr(types.NewPtr(types.Types[types.TUINT8]))) // ***uint8
    94  	_ = types.NewPtr(types.Types[types.TINT16])                             // *int16
    95  	_ = types.NewPtr(types.Types[types.TINT64])                             // *int64
    96  	_ = types.NewPtr(types.ErrorType)                                       // *error
    97  	_ = types.NewPtr(reflectdata.MapType())                                 // *internal/runtime/maps.Map
    98  	_ = types.NewPtr(deferstruct())                                         // *runtime._defer
    99  	types.NewPtrCacheEnabled = false
   100  	ssaConfig = ssa.NewConfig(base.Ctxt.Arch.Name, *types_, base.Ctxt, base.Flag.N == 0, Arch.SoftFloat)
   101  	ssaConfig.Race = base.Flag.Race
   102  	ssaCaches = make([]ssa.Cache, base.Flag.LowerC)
   103  
   104  	// Set up some runtime functions we'll need to call.
   105  	ir.Syms.AssertE2I = typecheck.LookupRuntimeFunc("assertE2I")
   106  	ir.Syms.AssertE2I2 = typecheck.LookupRuntimeFunc("assertE2I2")
   107  	ir.Syms.CgoCheckMemmove = typecheck.LookupRuntimeFunc("cgoCheckMemmove")
   108  	ir.Syms.CgoCheckPtrWrite = typecheck.LookupRuntimeFunc("cgoCheckPtrWrite")
   109  	ir.Syms.CheckPtrAlignment = typecheck.LookupRuntimeFunc("checkptrAlignment")
   110  	ir.Syms.Deferproc = typecheck.LookupRuntimeFunc("deferproc")
   111  	ir.Syms.Deferprocat = typecheck.LookupRuntimeFunc("deferprocat")
   112  	ir.Syms.DeferprocStack = typecheck.LookupRuntimeFunc("deferprocStack")
   113  	ir.Syms.Deferreturn = typecheck.LookupRuntimeFunc("deferreturn")
   114  	ir.Syms.Duffcopy = typecheck.LookupRuntimeFunc("duffcopy")
   115  	ir.Syms.Duffzero = typecheck.LookupRuntimeFunc("duffzero")
   116  	ir.Syms.GCWriteBarrier[0] = typecheck.LookupRuntimeFunc("gcWriteBarrier1")
   117  	ir.Syms.GCWriteBarrier[1] = typecheck.LookupRuntimeFunc("gcWriteBarrier2")
   118  	ir.Syms.GCWriteBarrier[2] = typecheck.LookupRuntimeFunc("gcWriteBarrier3")
   119  	ir.Syms.GCWriteBarrier[3] = typecheck.LookupRuntimeFunc("gcWriteBarrier4")
   120  	ir.Syms.GCWriteBarrier[4] = typecheck.LookupRuntimeFunc("gcWriteBarrier5")
   121  	ir.Syms.GCWriteBarrier[5] = typecheck.LookupRuntimeFunc("gcWriteBarrier6")
   122  	ir.Syms.GCWriteBarrier[6] = typecheck.LookupRuntimeFunc("gcWriteBarrier7")
   123  	ir.Syms.GCWriteBarrier[7] = typecheck.LookupRuntimeFunc("gcWriteBarrier8")
   124  	ir.Syms.Goschedguarded = typecheck.LookupRuntimeFunc("goschedguarded")
   125  	ir.Syms.Growslice = typecheck.LookupRuntimeFunc("growslice")
   126  	ir.Syms.InterfaceSwitch = typecheck.LookupRuntimeFunc("interfaceSwitch")
   127  	ir.Syms.MallocGC = typecheck.LookupRuntimeFunc("mallocgc")
   128  	ir.Syms.Memmove = typecheck.LookupRuntimeFunc("memmove")
   129  	ir.Syms.Msanread = typecheck.LookupRuntimeFunc("msanread")
   130  	ir.Syms.Msanwrite = typecheck.LookupRuntimeFunc("msanwrite")
   131  	ir.Syms.Msanmove = typecheck.LookupRuntimeFunc("msanmove")
   132  	ir.Syms.Asanread = typecheck.LookupRuntimeFunc("asanread")
   133  	ir.Syms.Asanwrite = typecheck.LookupRuntimeFunc("asanwrite")
   134  	ir.Syms.Newobject = typecheck.LookupRuntimeFunc("newobject")
   135  	ir.Syms.Newproc = typecheck.LookupRuntimeFunc("newproc")
   136  	ir.Syms.PanicBounds = typecheck.LookupRuntimeFunc("panicBounds")
   137  	ir.Syms.PanicExtend = typecheck.LookupRuntimeFunc("panicExtend")
   138  	ir.Syms.Panicdivide = typecheck.LookupRuntimeFunc("panicdivide")
   139  	ir.Syms.PanicdottypeE = typecheck.LookupRuntimeFunc("panicdottypeE")
   140  	ir.Syms.PanicdottypeI = typecheck.LookupRuntimeFunc("panicdottypeI")
   141  	ir.Syms.Panicnildottype = typecheck.LookupRuntimeFunc("panicnildottype")
   142  	ir.Syms.Panicoverflow = typecheck.LookupRuntimeFunc("panicoverflow")
   143  	ir.Syms.Panicshift = typecheck.LookupRuntimeFunc("panicshift")
   144  	ir.Syms.Racefuncenter = typecheck.LookupRuntimeFunc("racefuncenter")
   145  	ir.Syms.Racefuncexit = typecheck.LookupRuntimeFunc("racefuncexit")
   146  	ir.Syms.Raceread = typecheck.LookupRuntimeFunc("raceread")
   147  	ir.Syms.Racereadrange = typecheck.LookupRuntimeFunc("racereadrange")
   148  	ir.Syms.Racewrite = typecheck.LookupRuntimeFunc("racewrite")
   149  	ir.Syms.Racewriterange = typecheck.LookupRuntimeFunc("racewriterange")
   150  	ir.Syms.TypeAssert = typecheck.LookupRuntimeFunc("typeAssert")
   151  	ir.Syms.WBZero = typecheck.LookupRuntimeFunc("wbZero")
   152  	ir.Syms.WBMove = typecheck.LookupRuntimeFunc("wbMove")
   153  	ir.Syms.X86HasPOPCNT = typecheck.LookupRuntimeVar("x86HasPOPCNT")         // bool
   154  	ir.Syms.X86HasSSE41 = typecheck.LookupRuntimeVar("x86HasSSE41")           // bool
   155  	ir.Syms.X86HasFMA = typecheck.LookupRuntimeVar("x86HasFMA")               // bool
   156  	ir.Syms.ARMHasVFPv4 = typecheck.LookupRuntimeVar("armHasVFPv4")           // bool
   157  	ir.Syms.ARM64HasATOMICS = typecheck.LookupRuntimeVar("arm64HasATOMICS")   // bool
   158  	ir.Syms.Loong64HasLAMCAS = typecheck.LookupRuntimeVar("loong64HasLAMCAS") // bool
   159  	ir.Syms.Loong64HasLAM_BH = typecheck.LookupRuntimeVar("loong64HasLAM_BH") // bool
   160  	ir.Syms.Loong64HasLSX = typecheck.LookupRuntimeVar("loong64HasLSX")       // bool
   161  	ir.Syms.RISCV64HasZbb = typecheck.LookupRuntimeVar("riscv64HasZbb")       // bool
   162  	ir.Syms.Staticuint64s = typecheck.LookupRuntimeVar("staticuint64s")
   163  	ir.Syms.Typedmemmove = typecheck.LookupRuntimeFunc("typedmemmove")
   164  	ir.Syms.Udiv = typecheck.LookupRuntimeVar("udiv")                 // asm func with special ABI
   165  	ir.Syms.WriteBarrier = typecheck.LookupRuntimeVar("writeBarrier") // struct { bool; ... }
   166  	ir.Syms.Zerobase = typecheck.LookupRuntimeVar("zerobase")
   167  	ir.Syms.ZeroVal = typecheck.LookupRuntimeVar("zeroVal")
   168  
   169  	if Arch.LinkArch.Family == sys.Wasm {
   170  		BoundsCheckFunc[ssa.BoundsIndex] = typecheck.LookupRuntimeFunc("goPanicIndex")
   171  		BoundsCheckFunc[ssa.BoundsIndexU] = typecheck.LookupRuntimeFunc("goPanicIndexU")
   172  		BoundsCheckFunc[ssa.BoundsSliceAlen] = typecheck.LookupRuntimeFunc("goPanicSliceAlen")
   173  		BoundsCheckFunc[ssa.BoundsSliceAlenU] = typecheck.LookupRuntimeFunc("goPanicSliceAlenU")
   174  		BoundsCheckFunc[ssa.BoundsSliceAcap] = typecheck.LookupRuntimeFunc("goPanicSliceAcap")
   175  		BoundsCheckFunc[ssa.BoundsSliceAcapU] = typecheck.LookupRuntimeFunc("goPanicSliceAcapU")
   176  		BoundsCheckFunc[ssa.BoundsSliceB] = typecheck.LookupRuntimeFunc("goPanicSliceB")
   177  		BoundsCheckFunc[ssa.BoundsSliceBU] = typecheck.LookupRuntimeFunc("goPanicSliceBU")
   178  		BoundsCheckFunc[ssa.BoundsSlice3Alen] = typecheck.LookupRuntimeFunc("goPanicSlice3Alen")
   179  		BoundsCheckFunc[ssa.BoundsSlice3AlenU] = typecheck.LookupRuntimeFunc("goPanicSlice3AlenU")
   180  		BoundsCheckFunc[ssa.BoundsSlice3Acap] = typecheck.LookupRuntimeFunc("goPanicSlice3Acap")
   181  		BoundsCheckFunc[ssa.BoundsSlice3AcapU] = typecheck.LookupRuntimeFunc("goPanicSlice3AcapU")
   182  		BoundsCheckFunc[ssa.BoundsSlice3B] = typecheck.LookupRuntimeFunc("goPanicSlice3B")
   183  		BoundsCheckFunc[ssa.BoundsSlice3BU] = typecheck.LookupRuntimeFunc("goPanicSlice3BU")
   184  		BoundsCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeFunc("goPanicSlice3C")
   185  		BoundsCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeFunc("goPanicSlice3CU")
   186  		BoundsCheckFunc[ssa.BoundsConvert] = typecheck.LookupRuntimeFunc("goPanicSliceConvert")
   187  	}
   188  
   189  	// Wasm (all asm funcs with special ABIs)
   190  	ir.Syms.WasmDiv = typecheck.LookupRuntimeVar("wasmDiv")
   191  	ir.Syms.WasmTruncS = typecheck.LookupRuntimeVar("wasmTruncS")
   192  	ir.Syms.WasmTruncU = typecheck.LookupRuntimeVar("wasmTruncU")
   193  	ir.Syms.SigPanic = typecheck.LookupRuntimeFunc("sigpanic")
   194  }
   195  
   196  func InitTables() {
   197  	initIntrinsics(nil)
   198  }
   199  
   200  // AbiForBodylessFuncStackMap returns the ABI for a bodyless function's stack map.
   201  // This is not necessarily the ABI used to call it.
   202  // Currently (1.17 dev) such a stack map is always ABI0;
   203  // any ABI wrapper that is present is nosplit, hence a precise
   204  // stack map is not needed there (the parameters survive only long
   205  // enough to call the wrapped assembly function).
   206  // This always returns a freshly copied ABI.
   207  func AbiForBodylessFuncStackMap(fn *ir.Func) *abi.ABIConfig {
   208  	return ssaConfig.ABI0.Copy() // No idea what races will result, be safe
   209  }
   210  
   211  // abiForFunc implements ABI policy for a function, but does not return a copy of the ABI.
   212  // Passing a nil function returns the default ABI based on experiment configuration.
   213  func abiForFunc(fn *ir.Func, abi0, abi1 *abi.ABIConfig) *abi.ABIConfig {
   214  	if buildcfg.Experiment.RegabiArgs {
   215  		// Select the ABI based on the function's defining ABI.
   216  		if fn == nil {
   217  			return abi1
   218  		}
   219  		switch fn.ABI {
   220  		case obj.ABI0:
   221  			return abi0
   222  		case obj.ABIInternal:
   223  			// TODO(austin): Clean up the nomenclature here.
   224  			// It's not clear that "abi1" is ABIInternal.
   225  			return abi1
   226  		}
   227  		base.Fatalf("function %v has unknown ABI %v", fn, fn.ABI)
   228  		panic("not reachable")
   229  	}
   230  
   231  	a := abi0
   232  	if fn != nil {
   233  		if fn.Pragma&ir.RegisterParams != 0 { // TODO(register args) remove after register abi is working
   234  			a = abi1
   235  		}
   236  	}
   237  	return a
   238  }
   239  
   240  // emitOpenDeferInfo emits FUNCDATA information about the defers in a function
   241  // that is using open-coded defers.  This funcdata is used to determine the active
   242  // defers in a function and execute those defers during panic processing.
   243  //
   244  // The funcdata is all encoded in varints (since values will almost always be less than
   245  // 128, but stack offsets could potentially be up to 2Gbyte). All "locations" (offsets)
   246  // for stack variables are specified as the number of bytes below varp (pointer to the
   247  // top of the local variables) for their starting address. The format is:
   248  //
   249  //   - Offset of the deferBits variable
   250  //   - Offset of the first closure slot (the rest are laid out consecutively).
   251  func (s *state) emitOpenDeferInfo() {
   252  	firstOffset := s.openDefers[0].closureNode.FrameOffset()
   253  
   254  	// Verify that cmpstackvarlt laid out the slots in order.
   255  	for i, r := range s.openDefers {
   256  		have := r.closureNode.FrameOffset()
   257  		want := firstOffset + int64(i)*int64(types.PtrSize)
   258  		if have != want {
   259  			base.FatalfAt(s.curfn.Pos(), "unexpected frame offset for open-coded defer slot #%v: have %v, want %v", i, have, want)
   260  		}
   261  	}
   262  
   263  	x := base.Ctxt.Lookup(s.curfn.LSym.Name + ".opendefer")
   264  	x.Set(obj.AttrContentAddressable, true)
   265  	s.curfn.LSym.Func().OpenCodedDeferInfo = x
   266  
   267  	off := 0
   268  	off = objw.Uvarint(x, off, uint64(-s.deferBitsTemp.FrameOffset()))
   269  	off = objw.Uvarint(x, off, uint64(-firstOffset))
   270  }
   271  
   272  // buildssa builds an SSA function for fn.
   273  // worker indicates which of the backend workers is doing the processing.
   274  func buildssa(fn *ir.Func, worker int, isPgoHot bool) *ssa.Func {
   275  	name := ir.FuncName(fn)
   276  
   277  	abiSelf := abiForFunc(fn, ssaConfig.ABI0, ssaConfig.ABI1)
   278  
   279  	printssa := false
   280  	// match either a simple name e.g. "(*Reader).Reset", package.name e.g. "compress/gzip.(*Reader).Reset", or subpackage name "gzip.(*Reader).Reset"
   281  	// optionally allows an ABI suffix specification in the GOSSAHASH, e.g. "(*Reader).Reset<0>" etc
   282  	if strings.Contains(ssaDump, name) { // in all the cases the function name is entirely contained within the GOSSAFUNC string.
   283  		nameOptABI := name
   284  		if l := len(ssaDump); l > 1 && ssaDump[l-2] == ',' { // ABI specification
   285  			nameOptABI = ssa.FuncNameABI(name, abiSelf.Which())
   286  		} else if strings.HasSuffix(ssaDump, ">") { // if they use the linker syntax instead....
   287  			l := len(ssaDump)
   288  			if l >= 3 && ssaDump[l-3] == '<' {
   289  				nameOptABI = ssa.FuncNameABI(name, abiSelf.Which())
   290  				ssaDump = ssaDump[:l-3] + "," + ssaDump[l-2:l-1]
   291  			}
   292  		}
   293  		pkgDotName := base.Ctxt.Pkgpath + "." + nameOptABI
   294  		printssa = nameOptABI == ssaDump || // "(*Reader).Reset"
   295  			pkgDotName == ssaDump || // "compress/gzip.(*Reader).Reset"
   296  			strings.HasSuffix(pkgDotName, ssaDump) && strings.HasSuffix(pkgDotName, "/"+ssaDump) // "gzip.(*Reader).Reset"
   297  	}
   298  
   299  	var astBuf *bytes.Buffer
   300  	if printssa {
   301  		astBuf = &bytes.Buffer{}
   302  		ir.FDumpList(astBuf, "buildssa-body", fn.Body)
   303  		if ssaDumpStdout {
   304  			fmt.Println("generating SSA for", name)
   305  			fmt.Print(astBuf.String())
   306  		}
   307  	}
   308  
   309  	var s state
   310  	s.pushLine(fn.Pos())
   311  	defer s.popLine()
   312  
   313  	s.hasdefer = fn.HasDefer()
   314  	if fn.Pragma&ir.CgoUnsafeArgs != 0 {
   315  		s.cgoUnsafeArgs = true
   316  	}
   317  	s.checkPtrEnabled = ir.ShouldCheckPtr(fn, 1)
   318  
   319  	if base.Flag.Cfg.Instrumenting && fn.Pragma&ir.Norace == 0 && !fn.Linksym().ABIWrapper() {
   320  		if !base.Flag.Race || !objabi.LookupPkgSpecial(fn.Sym().Pkg.Path).NoRaceFunc {
   321  			s.instrumentMemory = true
   322  		}
   323  		if base.Flag.Race {
   324  			s.instrumentEnterExit = true
   325  		}
   326  	}
   327  
   328  	fe := ssafn{
   329  		curfn: fn,
   330  		log:   printssa && ssaDumpStdout,
   331  	}
   332  	s.curfn = fn
   333  
   334  	cache := &ssaCaches[worker]
   335  	cache.Reset()
   336  
   337  	s.f = ssaConfig.NewFunc(&fe, cache)
   338  	s.config = ssaConfig
   339  	s.f.Type = fn.Type()
   340  	s.f.Name = name
   341  	s.f.PrintOrHtmlSSA = printssa
   342  	if fn.Pragma&ir.Nosplit != 0 {
   343  		s.f.NoSplit = true
   344  	}
   345  	s.f.ABI0 = ssaConfig.ABI0
   346  	s.f.ABI1 = ssaConfig.ABI1
   347  	s.f.ABIDefault = abiForFunc(nil, ssaConfig.ABI0, ssaConfig.ABI1)
   348  	s.f.ABISelf = abiSelf
   349  
   350  	s.panics = map[funcLine]*ssa.Block{}
   351  	s.softFloat = s.config.SoftFloat
   352  
   353  	// Allocate starting block
   354  	s.f.Entry = s.f.NewBlock(ssa.BlockPlain)
   355  	s.f.Entry.Pos = fn.Pos()
   356  	s.f.IsPgoHot = isPgoHot
   357  
   358  	if printssa {
   359  		ssaDF := ssaDumpFile
   360  		if ssaDir != "" {
   361  			ssaDF = filepath.Join(ssaDir, base.Ctxt.Pkgpath+"."+s.f.NameABI()+".html")
   362  			ssaD := filepath.Dir(ssaDF)
   363  			os.MkdirAll(ssaD, 0755)
   364  		}
   365  		s.f.HTMLWriter = ssa.NewHTMLWriter(ssaDF, s.f, ssaDumpCFG)
   366  		// TODO: generate and print a mapping from nodes to values and blocks
   367  		dumpSourcesColumn(s.f.HTMLWriter, fn)
   368  		s.f.HTMLWriter.WriteAST("AST", astBuf)
   369  	}
   370  
   371  	// Allocate starting values
   372  	s.labels = map[string]*ssaLabel{}
   373  	s.fwdVars = map[ir.Node]*ssa.Value{}
   374  	s.startmem = s.entryNewValue0(ssa.OpInitMem, types.TypeMem)
   375  
   376  	s.hasOpenDefers = base.Flag.N == 0 && s.hasdefer && !s.curfn.OpenCodedDeferDisallowed()
   377  	switch {
   378  	case base.Debug.NoOpenDefer != 0:
   379  		s.hasOpenDefers = false
   380  	case s.hasOpenDefers && (base.Ctxt.Flag_shared || base.Ctxt.Flag_dynlink) && base.Ctxt.Arch.Name == "386":
   381  		// Don't support open-coded defers for 386 ONLY when using shared
   382  		// libraries, because there is extra code (added by rewriteToUseGot())
   383  		// preceding the deferreturn/ret code that we don't track correctly.
   384  		//
   385  		// TODO this restriction can be removed given adjusted offset in computeDeferReturn in cmd/link/internal/ld/pcln.go
   386  		s.hasOpenDefers = false
   387  	}
   388  	if s.hasOpenDefers && s.instrumentEnterExit {
   389  		// Skip doing open defers if we need to instrument function
   390  		// returns for the race detector, since we will not generate that
   391  		// code in the case of the extra deferreturn/ret segment.
   392  		s.hasOpenDefers = false
   393  	}
   394  	if s.hasOpenDefers {
   395  		// Similarly, skip if there are any heap-allocated result
   396  		// parameters that need to be copied back to their stack slots.
   397  		for _, f := range s.curfn.Type().Results() {
   398  			if !f.Nname.(*ir.Name).OnStack() {
   399  				s.hasOpenDefers = false
   400  				break
   401  			}
   402  		}
   403  	}
   404  	if s.hasOpenDefers &&
   405  		s.curfn.NumReturns*s.curfn.NumDefers > 15 {
   406  		// Since we are generating defer calls at every exit for
   407  		// open-coded defers, skip doing open-coded defers if there are
   408  		// too many returns (especially if there are multiple defers).
   409  		// Open-coded defers are most important for improving performance
   410  		// for smaller functions (which don't have many returns).
   411  		s.hasOpenDefers = false
   412  	}
   413  
   414  	s.sp = s.entryNewValue0(ssa.OpSP, types.Types[types.TUINTPTR]) // TODO: use generic pointer type (unsafe.Pointer?) instead
   415  	s.sb = s.entryNewValue0(ssa.OpSB, types.Types[types.TUINTPTR])
   416  
   417  	s.startBlock(s.f.Entry)
   418  	s.vars[memVar] = s.startmem
   419  	if s.hasOpenDefers {
   420  		// Create the deferBits variable and stack slot.  deferBits is a
   421  		// bitmask showing which of the open-coded defers in this function
   422  		// have been activated.
   423  		deferBitsTemp := typecheck.TempAt(src.NoXPos, s.curfn, types.Types[types.TUINT8])
   424  		deferBitsTemp.SetAddrtaken(true)
   425  		s.deferBitsTemp = deferBitsTemp
   426  		// For this value, AuxInt is initialized to zero by default
   427  		startDeferBits := s.entryNewValue0(ssa.OpConst8, types.Types[types.TUINT8])
   428  		s.vars[deferBitsVar] = startDeferBits
   429  		s.deferBitsAddr = s.addr(deferBitsTemp)
   430  		s.store(types.Types[types.TUINT8], s.deferBitsAddr, startDeferBits)
   431  		// Make sure that the deferBits stack slot is kept alive (for use
   432  		// by panics) and stores to deferBits are not eliminated, even if
   433  		// all checking code on deferBits in the function exit can be
   434  		// eliminated, because the defer statements were all
   435  		// unconditional.
   436  		s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, deferBitsTemp, s.mem(), false)
   437  	}
   438  
   439  	var params *abi.ABIParamResultInfo
   440  	params = s.f.ABISelf.ABIAnalyze(fn.Type(), true)
   441  
   442  	// The backend's stackframe pass prunes away entries from the fn's
   443  	// Dcl list, including PARAMOUT nodes that correspond to output
   444  	// params passed in registers. Walk the Dcl list and capture these
   445  	// nodes to a side list, so that we'll have them available during
   446  	// DWARF-gen later on. See issue 48573 for more details.
   447  	var debugInfo ssa.FuncDebug
   448  	for _, n := range fn.Dcl {
   449  		if n.Class == ir.PPARAMOUT && n.IsOutputParamInRegisters() {
   450  			debugInfo.RegOutputParams = append(debugInfo.RegOutputParams, n)
   451  		}
   452  	}
   453  	fn.DebugInfo = &debugInfo
   454  
   455  	// Generate addresses of local declarations
   456  	s.decladdrs = map[*ir.Name]*ssa.Value{}
   457  	for _, n := range fn.Dcl {
   458  		switch n.Class {
   459  		case ir.PPARAM:
   460  			// Be aware that blank and unnamed input parameters will not appear here, but do appear in the type
   461  			s.decladdrs[n] = s.entryNewValue2A(ssa.OpLocalAddr, types.NewPtr(n.Type()), n, s.sp, s.startmem)
   462  		case ir.PPARAMOUT:
   463  			s.decladdrs[n] = s.entryNewValue2A(ssa.OpLocalAddr, types.NewPtr(n.Type()), n, s.sp, s.startmem)
   464  		case ir.PAUTO:
   465  			// processed at each use, to prevent Addr coming
   466  			// before the decl.
   467  		default:
   468  			s.Fatalf("local variable with class %v unimplemented", n.Class)
   469  		}
   470  	}
   471  
   472  	s.f.OwnAux = ssa.OwnAuxCall(fn.LSym, params)
   473  
   474  	// Populate SSAable arguments.
   475  	for _, n := range fn.Dcl {
   476  		if n.Class == ir.PPARAM {
   477  			if s.canSSA(n) {
   478  				v := s.newValue0A(ssa.OpArg, n.Type(), n)
   479  				s.vars[n] = v
   480  				s.addNamedValue(n, v) // This helps with debugging information, not needed for compilation itself.
   481  			} else { // address was taken AND/OR too large for SSA
   482  				paramAssignment := ssa.ParamAssignmentForArgName(s.f, n)
   483  				if len(paramAssignment.Registers) > 0 {
   484  					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.
   485  						v := s.newValue0A(ssa.OpArg, n.Type(), n)
   486  						s.store(n.Type(), s.decladdrs[n], v)
   487  					} else { // Too big for SSA.
   488  						// Brute force, and early, do a bunch of stores from registers
   489  						// Note that expand calls knows about this and doesn't trouble itself with larger-than-SSA-able Args in registers.
   490  						s.storeParameterRegsToStack(s.f.ABISelf, paramAssignment, n, s.decladdrs[n], false)
   491  					}
   492  				}
   493  			}
   494  		}
   495  	}
   496  
   497  	// Populate closure variables.
   498  	if fn.Needctxt() {
   499  		clo := s.entryNewValue0(ssa.OpGetClosurePtr, s.f.Config.Types.BytePtr)
   500  		if fn.RangeParent != nil && base.Flag.N != 0 {
   501  			// For a range body closure, keep its closure pointer live on the
   502  			// stack with a special name, so the debugger can look for it and
   503  			// find the parent frame.
   504  			sym := &types.Sym{Name: ".closureptr", Pkg: types.LocalPkg}
   505  			cloSlot := s.curfn.NewLocal(src.NoXPos, sym, s.f.Config.Types.BytePtr)
   506  			cloSlot.SetUsed(true)
   507  			cloSlot.SetEsc(ir.EscNever)
   508  			cloSlot.SetAddrtaken(true)
   509  			s.f.CloSlot = cloSlot
   510  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, cloSlot, s.mem(), false)
   511  			addr := s.addr(cloSlot)
   512  			s.store(s.f.Config.Types.BytePtr, addr, clo)
   513  			// Keep it from being dead-store eliminated.
   514  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, cloSlot, s.mem(), false)
   515  		}
   516  		csiter := typecheck.NewClosureStructIter(fn.ClosureVars)
   517  		for {
   518  			n, typ, offset := csiter.Next()
   519  			if n == nil {
   520  				break
   521  			}
   522  
   523  			ptr := s.newValue1I(ssa.OpOffPtr, types.NewPtr(typ), offset, clo)
   524  
   525  			// If n is a small variable captured by value, promote
   526  			// it to PAUTO so it can be converted to SSA.
   527  			//
   528  			// Note: While we never capture a variable by value if
   529  			// the user took its address, we may have generated
   530  			// runtime calls that did (#43701). Since we don't
   531  			// convert Addrtaken variables to SSA anyway, no point
   532  			// in promoting them either.
   533  			if n.Byval() && !n.Addrtaken() && ssa.CanSSA(n.Type()) {
   534  				n.Class = ir.PAUTO
   535  				fn.Dcl = append(fn.Dcl, n)
   536  				s.assign(n, s.load(n.Type(), ptr), false, 0)
   537  				continue
   538  			}
   539  
   540  			if !n.Byval() {
   541  				ptr = s.load(typ, ptr)
   542  			}
   543  			s.setHeapaddr(fn.Pos(), n, ptr)
   544  		}
   545  	}
   546  
   547  	// Convert the AST-based IR to the SSA-based IR
   548  	if s.instrumentEnterExit {
   549  		s.rtcall(ir.Syms.Racefuncenter, true, nil, s.newValue0(ssa.OpGetCallerPC, types.Types[types.TUINTPTR]))
   550  	}
   551  	s.zeroResults()
   552  	s.paramsToHeap()
   553  	s.stmtList(fn.Body)
   554  
   555  	// fallthrough to exit
   556  	if s.curBlock != nil {
   557  		s.pushLine(fn.Endlineno)
   558  		s.exit()
   559  		s.popLine()
   560  	}
   561  
   562  	for _, b := range s.f.Blocks {
   563  		if b.Pos != src.NoXPos {
   564  			s.updateUnsetPredPos(b)
   565  		}
   566  	}
   567  
   568  	s.f.HTMLWriter.WritePhase("before insert phis", "before insert phis")
   569  
   570  	s.insertPhis()
   571  
   572  	// Main call to ssa package to compile function
   573  	ssa.Compile(s.f)
   574  
   575  	fe.AllocFrame(s.f)
   576  
   577  	if len(s.openDefers) != 0 {
   578  		s.emitOpenDeferInfo()
   579  	}
   580  
   581  	// Record incoming parameter spill information for morestack calls emitted in the assembler.
   582  	// This is done here, using all the parameters (used, partially used, and unused) because
   583  	// it mimics the behavior of the former ABI (everything stored) and because it's not 100%
   584  	// clear if naming conventions are respected in autogenerated code.
   585  	// TODO figure out exactly what's unused, don't spill it. Make liveness fine-grained, also.
   586  	for _, p := range params.InParams() {
   587  		typs, offs := p.RegisterTypesAndOffsets()
   588  		for i, t := range typs {
   589  			o := offs[i]                // offset within parameter
   590  			fo := p.FrameOffset(params) // offset of parameter in frame
   591  			reg := ssa.ObjRegForAbiReg(p.Registers[i], s.f.Config)
   592  			s.f.RegArgs = append(s.f.RegArgs, ssa.Spill{Reg: reg, Offset: fo + o, Type: t})
   593  		}
   594  	}
   595  
   596  	return s.f
   597  }
   598  
   599  func (s *state) storeParameterRegsToStack(abi *abi.ABIConfig, paramAssignment *abi.ABIParamAssignment, n *ir.Name, addr *ssa.Value, pointersOnly bool) {
   600  	typs, offs := paramAssignment.RegisterTypesAndOffsets()
   601  	for i, t := range typs {
   602  		if pointersOnly && !t.IsPtrShaped() {
   603  			continue
   604  		}
   605  		r := paramAssignment.Registers[i]
   606  		o := offs[i]
   607  		op, reg := ssa.ArgOpAndRegisterFor(r, abi)
   608  		aux := &ssa.AuxNameOffset{Name: n, Offset: o}
   609  		v := s.newValue0I(op, t, reg)
   610  		v.Aux = aux
   611  		p := s.newValue1I(ssa.OpOffPtr, types.NewPtr(t), o, addr)
   612  		s.store(t, p, v)
   613  	}
   614  }
   615  
   616  // zeroResults zeros the return values at the start of the function.
   617  // We need to do this very early in the function.  Defer might stop a
   618  // panic and show the return values as they exist at the time of
   619  // panic.  For precise stacks, the garbage collector assumes results
   620  // are always live, so we need to zero them before any allocations,
   621  // even allocations to move params/results to the heap.
   622  func (s *state) zeroResults() {
   623  	for _, f := range s.curfn.Type().Results() {
   624  		n := f.Nname.(*ir.Name)
   625  		if !n.OnStack() {
   626  			// The local which points to the return value is the
   627  			// thing that needs zeroing. This is already handled
   628  			// by a Needzero annotation in plive.go:(*liveness).epilogue.
   629  			continue
   630  		}
   631  		// Zero the stack location containing f.
   632  		if typ := n.Type(); ssa.CanSSA(typ) {
   633  			s.assign(n, s.zeroVal(typ), false, 0)
   634  		} else {
   635  			if typ.HasPointers() || ssa.IsMergeCandidate(n) {
   636  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
   637  			}
   638  			s.zero(n.Type(), s.decladdrs[n])
   639  		}
   640  	}
   641  }
   642  
   643  // paramsToHeap produces code to allocate memory for heap-escaped parameters
   644  // and to copy non-result parameters' values from the stack.
   645  func (s *state) paramsToHeap() {
   646  	do := func(params []*types.Field) {
   647  		for _, f := range params {
   648  			if f.Nname == nil {
   649  				continue // anonymous or blank parameter
   650  			}
   651  			n := f.Nname.(*ir.Name)
   652  			if ir.IsBlank(n) || n.OnStack() {
   653  				continue
   654  			}
   655  			s.newHeapaddr(n)
   656  			if n.Class == ir.PPARAM {
   657  				s.move(n.Type(), s.expr(n.Heapaddr), s.decladdrs[n])
   658  			}
   659  		}
   660  	}
   661  
   662  	typ := s.curfn.Type()
   663  	do(typ.Recvs())
   664  	do(typ.Params())
   665  	do(typ.Results())
   666  }
   667  
   668  // allocSizeAndAlign returns the size and alignment of t.
   669  // Normally just t.Size() and t.Alignment(), but there
   670  // is a special case to handle 64-bit atomics on 32-bit systems.
   671  func allocSizeAndAlign(t *types.Type) (int64, int64) {
   672  	size, align := t.Size(), t.Alignment()
   673  	if types.PtrSize == 4 && align == 4 && size >= 8 {
   674  		// For 64-bit atomics on 32-bit systems.
   675  		size = types.RoundUp(size, 8)
   676  		align = 8
   677  	}
   678  	return size, align
   679  }
   680  func allocSize(t *types.Type) int64 {
   681  	size, _ := allocSizeAndAlign(t)
   682  	return size
   683  }
   684  func allocAlign(t *types.Type) int64 {
   685  	_, align := allocSizeAndAlign(t)
   686  	return align
   687  }
   688  
   689  // newHeapaddr allocates heap memory for n and sets its heap address.
   690  func (s *state) newHeapaddr(n *ir.Name) {
   691  	size := allocSize(n.Type())
   692  	if n.Type().HasPointers() || size >= maxAggregatedHeapAllocation || size == 0 {
   693  		s.setHeapaddr(n.Pos(), n, s.newObject(n.Type(), nil))
   694  		return
   695  	}
   696  
   697  	// Do we have room together with our pending allocations?
   698  	// If not, flush all the current ones.
   699  	var used int64
   700  	for _, v := range s.pendingHeapAllocations {
   701  		used += allocSize(v.Type.Elem())
   702  	}
   703  	if used+size > maxAggregatedHeapAllocation {
   704  		s.flushPendingHeapAllocations()
   705  	}
   706  
   707  	var allocCall *ssa.Value // (SelectN [0] (call of runtime.newobject))
   708  	if len(s.pendingHeapAllocations) == 0 {
   709  		// Make an allocation, but the type being allocated is just
   710  		// the first pending object. We will come back and update it
   711  		// later if needed.
   712  		allocCall = s.newObject(n.Type(), nil)
   713  	} else {
   714  		allocCall = s.pendingHeapAllocations[0].Args[0]
   715  	}
   716  	// v is an offset to the shared allocation. Offsets are dummy 0s for now.
   717  	v := s.newValue1I(ssa.OpOffPtr, n.Type().PtrTo(), 0, allocCall)
   718  
   719  	// Add to list of pending allocations.
   720  	s.pendingHeapAllocations = append(s.pendingHeapAllocations, v)
   721  
   722  	// Finally, record for posterity.
   723  	s.setHeapaddr(n.Pos(), n, v)
   724  }
   725  
   726  func (s *state) flushPendingHeapAllocations() {
   727  	pending := s.pendingHeapAllocations
   728  	if len(pending) == 0 {
   729  		return // nothing to do
   730  	}
   731  	s.pendingHeapAllocations = nil // reset state
   732  	ptr := pending[0].Args[0]      // The SelectN [0] op
   733  	call := ptr.Args[0]            // The runtime.newobject call
   734  
   735  	if len(pending) == 1 {
   736  		// Just a single object, do a standard allocation.
   737  		v := pending[0]
   738  		v.Op = ssa.OpCopy // instead of OffPtr [0]
   739  		return
   740  	}
   741  
   742  	// Sort in decreasing alignment.
   743  	// This way we never have to worry about padding.
   744  	// (Stable not required; just cleaner to keep program order among equal alignments.)
   745  	slices.SortStableFunc(pending, func(x, y *ssa.Value) int {
   746  		return cmp.Compare(allocAlign(y.Type.Elem()), allocAlign(x.Type.Elem()))
   747  	})
   748  
   749  	// Figure out how much data we need allocate.
   750  	var size int64
   751  	for _, v := range pending {
   752  		v.AuxInt = size // Adjust OffPtr to the right value while we are here.
   753  		size += allocSize(v.Type.Elem())
   754  	}
   755  	align := allocAlign(pending[0].Type.Elem())
   756  	size = types.RoundUp(size, align)
   757  
   758  	// Convert newObject call to a mallocgc call.
   759  	args := []*ssa.Value{
   760  		s.constInt(types.Types[types.TUINTPTR], size),
   761  		s.constNil(call.Args[0].Type), // a nil *runtime._type
   762  		s.constBool(true),             // needZero TODO: false is ok?
   763  		call.Args[1],                  // memory
   764  	}
   765  	call.Aux = ssa.StaticAuxCall(ir.Syms.MallocGC, s.f.ABIDefault.ABIAnalyzeTypes(
   766  		[]*types.Type{args[0].Type, args[1].Type, args[2].Type},
   767  		[]*types.Type{types.Types[types.TUNSAFEPTR]},
   768  	))
   769  	call.AuxInt = 4 * s.config.PtrSize // arg+results size, uintptr/ptr/bool/ptr
   770  	call.SetArgs4(args[0], args[1], args[2], args[3])
   771  	// TODO: figure out how to pass alignment to runtime
   772  
   773  	call.Type = types.NewTuple(types.Types[types.TUNSAFEPTR], types.TypeMem)
   774  	ptr.Type = types.Types[types.TUNSAFEPTR]
   775  }
   776  
   777  // setHeapaddr allocates a new PAUTO variable to store ptr (which must be non-nil)
   778  // and then sets it as n's heap address.
   779  func (s *state) setHeapaddr(pos src.XPos, n *ir.Name, ptr *ssa.Value) {
   780  	if !ptr.Type.IsPtr() || !types.Identical(n.Type(), ptr.Type.Elem()) {
   781  		base.FatalfAt(n.Pos(), "setHeapaddr %L with type %v", n, ptr.Type)
   782  	}
   783  
   784  	// Declare variable to hold address.
   785  	sym := &types.Sym{Name: "&" + n.Sym().Name, Pkg: types.LocalPkg}
   786  	addr := s.curfn.NewLocal(pos, sym, types.NewPtr(n.Type()))
   787  	addr.SetUsed(true)
   788  	types.CalcSize(addr.Type())
   789  
   790  	if n.Class == ir.PPARAMOUT {
   791  		addr.SetIsOutputParamHeapAddr(true)
   792  	}
   793  
   794  	n.Heapaddr = addr
   795  	s.assign(addr, ptr, false, 0)
   796  }
   797  
   798  // newObject returns an SSA value denoting new(typ).
   799  func (s *state) newObject(typ *types.Type, rtype *ssa.Value) *ssa.Value {
   800  	if typ.Size() == 0 {
   801  		return s.newValue1A(ssa.OpAddr, types.NewPtr(typ), ir.Syms.Zerobase, s.sb)
   802  	}
   803  	if rtype == nil {
   804  		rtype = s.reflectType(typ)
   805  	}
   806  	return s.rtcall(ir.Syms.Newobject, true, []*types.Type{types.NewPtr(typ)}, rtype)[0]
   807  }
   808  
   809  func (s *state) checkPtrAlignment(n *ir.ConvExpr, v *ssa.Value, count *ssa.Value) {
   810  	if !n.Type().IsPtr() {
   811  		s.Fatalf("expected pointer type: %v", n.Type())
   812  	}
   813  	elem, rtypeExpr := n.Type().Elem(), n.ElemRType
   814  	if count != nil {
   815  		if !elem.IsArray() {
   816  			s.Fatalf("expected array type: %v", elem)
   817  		}
   818  		elem, rtypeExpr = elem.Elem(), n.ElemElemRType
   819  	}
   820  	size := elem.Size()
   821  	// Casting from larger type to smaller one is ok, so for smallest type, do nothing.
   822  	if elem.Alignment() == 1 && (size == 0 || size == 1 || count == nil) {
   823  		return
   824  	}
   825  	if count == nil {
   826  		count = s.constInt(types.Types[types.TUINTPTR], 1)
   827  	}
   828  	if count.Type.Size() != s.config.PtrSize {
   829  		s.Fatalf("expected count fit to a uintptr size, have: %d, want: %d", count.Type.Size(), s.config.PtrSize)
   830  	}
   831  	var rtype *ssa.Value
   832  	if rtypeExpr != nil {
   833  		rtype = s.expr(rtypeExpr)
   834  	} else {
   835  		rtype = s.reflectType(elem)
   836  	}
   837  	s.rtcall(ir.Syms.CheckPtrAlignment, true, nil, v, rtype, count)
   838  }
   839  
   840  // reflectType returns an SSA value representing a pointer to typ's
   841  // reflection type descriptor.
   842  func (s *state) reflectType(typ *types.Type) *ssa.Value {
   843  	// TODO(mdempsky): Make this Fatalf under Unified IR; frontend needs
   844  	// to supply RType expressions.
   845  	lsym := reflectdata.TypeLinksym(typ)
   846  	return s.entryNewValue1A(ssa.OpAddr, types.NewPtr(types.Types[types.TUINT8]), lsym, s.sb)
   847  }
   848  
   849  func dumpSourcesColumn(writer *ssa.HTMLWriter, fn *ir.Func) {
   850  	// Read sources of target function fn.
   851  	fname := base.Ctxt.PosTable.Pos(fn.Pos()).Filename()
   852  	targetFn, err := readFuncLines(fname, fn.Pos().Line(), fn.Endlineno.Line())
   853  	if err != nil {
   854  		writer.Logf("cannot read sources for function %v: %v", fn, err)
   855  	}
   856  
   857  	// Read sources of inlined functions.
   858  	var inlFns []*ssa.FuncLines
   859  	for _, fi := range ssaDumpInlined {
   860  		elno := fi.Endlineno
   861  		fname := base.Ctxt.PosTable.Pos(fi.Pos()).Filename()
   862  		fnLines, err := readFuncLines(fname, fi.Pos().Line(), elno.Line())
   863  		if err != nil {
   864  			writer.Logf("cannot read sources for inlined function %v: %v", fi, err)
   865  			continue
   866  		}
   867  		inlFns = append(inlFns, fnLines)
   868  	}
   869  
   870  	slices.SortFunc(inlFns, ssa.ByTopoCmp)
   871  	if targetFn != nil {
   872  		inlFns = append([]*ssa.FuncLines{targetFn}, inlFns...)
   873  	}
   874  
   875  	writer.WriteSources("sources", inlFns)
   876  }
   877  
   878  func readFuncLines(file string, start, end uint) (*ssa.FuncLines, error) {
   879  	f, err := os.Open(os.ExpandEnv(file))
   880  	if err != nil {
   881  		return nil, err
   882  	}
   883  	defer f.Close()
   884  	var lines []string
   885  	ln := uint(1)
   886  	scanner := bufio.NewScanner(f)
   887  	for scanner.Scan() && ln <= end {
   888  		if ln >= start {
   889  			lines = append(lines, scanner.Text())
   890  		}
   891  		ln++
   892  	}
   893  	return &ssa.FuncLines{Filename: file, StartLineno: start, Lines: lines}, nil
   894  }
   895  
   896  // updateUnsetPredPos propagates the earliest-value position information for b
   897  // towards all of b's predecessors that need a position, and recurs on that
   898  // predecessor if its position is updated. B should have a non-empty position.
   899  func (s *state) updateUnsetPredPos(b *ssa.Block) {
   900  	if b.Pos == src.NoXPos {
   901  		s.Fatalf("Block %s should have a position", b)
   902  	}
   903  	bestPos := src.NoXPos
   904  	for _, e := range b.Preds {
   905  		p := e.Block()
   906  		if !p.LackingPos() {
   907  			continue
   908  		}
   909  		if bestPos == src.NoXPos {
   910  			bestPos = b.Pos
   911  			for _, v := range b.Values {
   912  				if v.LackingPos() {
   913  					continue
   914  				}
   915  				if v.Pos != src.NoXPos {
   916  					// Assume values are still in roughly textual order;
   917  					// TODO: could also seek minimum position?
   918  					bestPos = v.Pos
   919  					break
   920  				}
   921  			}
   922  		}
   923  		p.Pos = bestPos
   924  		s.updateUnsetPredPos(p) // We do not expect long chains of these, thus recursion is okay.
   925  	}
   926  }
   927  
   928  // Information about each open-coded defer.
   929  type openDeferInfo struct {
   930  	// The node representing the call of the defer
   931  	n *ir.CallExpr
   932  	// If defer call is closure call, the address of the argtmp where the
   933  	// closure is stored.
   934  	closure *ssa.Value
   935  	// The node representing the argtmp where the closure is stored - used for
   936  	// function, method, or interface call, to store a closure that panic
   937  	// processing can use for this defer.
   938  	closureNode *ir.Name
   939  }
   940  
   941  type state struct {
   942  	// configuration (arch) information
   943  	config *ssa.Config
   944  
   945  	// function we're building
   946  	f *ssa.Func
   947  
   948  	// Node for function
   949  	curfn *ir.Func
   950  
   951  	// labels in f
   952  	labels map[string]*ssaLabel
   953  
   954  	// unlabeled break and continue statement tracking
   955  	breakTo    *ssa.Block // current target for plain break statement
   956  	continueTo *ssa.Block // current target for plain continue statement
   957  
   958  	// current location where we're interpreting the AST
   959  	curBlock *ssa.Block
   960  
   961  	// variable assignments in the current block (map from variable symbol to ssa value)
   962  	// *Node is the unique identifier (an ONAME Node) for the variable.
   963  	// TODO: keep a single varnum map, then make all of these maps slices instead?
   964  	vars map[ir.Node]*ssa.Value
   965  
   966  	// fwdVars are variables that are used before they are defined in the current block.
   967  	// This map exists just to coalesce multiple references into a single FwdRef op.
   968  	// *Node is the unique identifier (an ONAME Node) for the variable.
   969  	fwdVars map[ir.Node]*ssa.Value
   970  
   971  	// all defined variables at the end of each block. Indexed by block ID.
   972  	defvars []map[ir.Node]*ssa.Value
   973  
   974  	// addresses of PPARAM and PPARAMOUT variables on the stack.
   975  	decladdrs map[*ir.Name]*ssa.Value
   976  
   977  	// starting values. Memory, stack pointer, and globals pointer
   978  	startmem *ssa.Value
   979  	sp       *ssa.Value
   980  	sb       *ssa.Value
   981  	// value representing address of where deferBits autotmp is stored
   982  	deferBitsAddr *ssa.Value
   983  	deferBitsTemp *ir.Name
   984  
   985  	// line number stack. The current line number is top of stack
   986  	line []src.XPos
   987  	// the last line number processed; it may have been popped
   988  	lastPos src.XPos
   989  
   990  	// list of panic calls by function name and line number.
   991  	// Used to deduplicate panic calls.
   992  	panics map[funcLine]*ssa.Block
   993  
   994  	cgoUnsafeArgs       bool
   995  	hasdefer            bool // whether the function contains a defer statement
   996  	softFloat           bool
   997  	hasOpenDefers       bool // whether we are doing open-coded defers
   998  	checkPtrEnabled     bool // whether to insert checkptr instrumentation
   999  	instrumentEnterExit bool // whether to instrument function enter/exit
  1000  	instrumentMemory    bool // whether to instrument memory operations
  1001  
  1002  	// If doing open-coded defers, list of info about the defer calls in
  1003  	// scanning order. Hence, at exit we should run these defers in reverse
  1004  	// order of this list
  1005  	openDefers []*openDeferInfo
  1006  	// For open-coded defers, this is the beginning and end blocks of the last
  1007  	// defer exit code that we have generated so far. We use these to share
  1008  	// code between exits if the shareDeferExits option (disabled by default)
  1009  	// is on.
  1010  	lastDeferExit       *ssa.Block // Entry block of last defer exit code we generated
  1011  	lastDeferFinalBlock *ssa.Block // Final block of last defer exit code we generated
  1012  	lastDeferCount      int        // Number of defers encountered at that point
  1013  
  1014  	prevCall *ssa.Value // the previous call; use this to tie results to the call op.
  1015  
  1016  	// List of allocations in the current block that are still pending.
  1017  	// They are all (OffPtr (Select0 (runtime call))) and have the correct types,
  1018  	// but the offsets are not set yet, and the type of the runtime call is also not final.
  1019  	pendingHeapAllocations []*ssa.Value
  1020  
  1021  	// First argument of append calls that could be stack allocated.
  1022  	appendTargets map[ir.Node]bool
  1023  }
  1024  
  1025  type funcLine struct {
  1026  	f    *obj.LSym
  1027  	base *src.PosBase
  1028  	line uint
  1029  }
  1030  
  1031  type ssaLabel struct {
  1032  	target         *ssa.Block // block identified by this label
  1033  	breakTarget    *ssa.Block // block to break to in control flow node identified by this label
  1034  	continueTarget *ssa.Block // block to continue to in control flow node identified by this label
  1035  }
  1036  
  1037  // label returns the label associated with sym, creating it if necessary.
  1038  func (s *state) label(sym *types.Sym) *ssaLabel {
  1039  	lab := s.labels[sym.Name]
  1040  	if lab == nil {
  1041  		lab = new(ssaLabel)
  1042  		s.labels[sym.Name] = lab
  1043  	}
  1044  	return lab
  1045  }
  1046  
  1047  func (s *state) Logf(msg string, args ...interface{}) { s.f.Logf(msg, args...) }
  1048  func (s *state) Log() bool                            { return s.f.Log() }
  1049  func (s *state) Fatalf(msg string, args ...interface{}) {
  1050  	s.f.Frontend().Fatalf(s.peekPos(), msg, args...)
  1051  }
  1052  func (s *state) Warnl(pos src.XPos, msg string, args ...interface{}) { s.f.Warnl(pos, msg, args...) }
  1053  func (s *state) Debug_checknil() bool                                { return s.f.Frontend().Debug_checknil() }
  1054  
  1055  func ssaMarker(name string) *ir.Name {
  1056  	return ir.NewNameAt(base.Pos, &types.Sym{Name: name}, nil)
  1057  }
  1058  
  1059  var (
  1060  	// marker node for the memory variable
  1061  	memVar = ssaMarker("mem")
  1062  
  1063  	// marker nodes for temporary variables
  1064  	ptrVar       = ssaMarker("ptr")
  1065  	lenVar       = ssaMarker("len")
  1066  	capVar       = ssaMarker("cap")
  1067  	typVar       = ssaMarker("typ")
  1068  	okVar        = ssaMarker("ok")
  1069  	deferBitsVar = ssaMarker("deferBits")
  1070  	hashVar      = ssaMarker("hash")
  1071  )
  1072  
  1073  // startBlock sets the current block we're generating code in to b.
  1074  func (s *state) startBlock(b *ssa.Block) {
  1075  	if s.curBlock != nil {
  1076  		s.Fatalf("starting block %v when block %v has not ended", b, s.curBlock)
  1077  	}
  1078  	s.curBlock = b
  1079  	s.vars = map[ir.Node]*ssa.Value{}
  1080  	clear(s.fwdVars)
  1081  }
  1082  
  1083  // endBlock marks the end of generating code for the current block.
  1084  // Returns the (former) current block. Returns nil if there is no current
  1085  // block, i.e. if no code flows to the current execution point.
  1086  func (s *state) endBlock() *ssa.Block {
  1087  	b := s.curBlock
  1088  	if b == nil {
  1089  		return nil
  1090  	}
  1091  
  1092  	s.flushPendingHeapAllocations()
  1093  
  1094  	for len(s.defvars) <= int(b.ID) {
  1095  		s.defvars = append(s.defvars, nil)
  1096  	}
  1097  	s.defvars[b.ID] = s.vars
  1098  	s.curBlock = nil
  1099  	s.vars = nil
  1100  	if b.LackingPos() {
  1101  		// Empty plain blocks get the line of their successor (handled after all blocks created),
  1102  		// except for increment blocks in For statements (handled in ssa conversion of OFOR),
  1103  		// and for blocks ending in GOTO/BREAK/CONTINUE.
  1104  		b.Pos = src.NoXPos
  1105  	} else {
  1106  		b.Pos = s.lastPos
  1107  	}
  1108  	return b
  1109  }
  1110  
  1111  // pushLine pushes a line number on the line number stack.
  1112  func (s *state) pushLine(line src.XPos) {
  1113  	if !line.IsKnown() {
  1114  		// the frontend may emit node with line number missing,
  1115  		// use the parent line number in this case.
  1116  		line = s.peekPos()
  1117  		if base.Flag.K != 0 {
  1118  			base.Warn("buildssa: unknown position (line 0)")
  1119  		}
  1120  	} else {
  1121  		s.lastPos = line
  1122  	}
  1123  
  1124  	s.line = append(s.line, line)
  1125  }
  1126  
  1127  // popLine pops the top of the line number stack.
  1128  func (s *state) popLine() {
  1129  	s.line = s.line[:len(s.line)-1]
  1130  }
  1131  
  1132  // peekPos peeks the top of the line number stack.
  1133  func (s *state) peekPos() src.XPos {
  1134  	return s.line[len(s.line)-1]
  1135  }
  1136  
  1137  // newValue0 adds a new value with no arguments to the current block.
  1138  func (s *state) newValue0(op ssa.Op, t *types.Type) *ssa.Value {
  1139  	return s.curBlock.NewValue0(s.peekPos(), op, t)
  1140  }
  1141  
  1142  // newValue0A adds a new value with no arguments and an aux value to the current block.
  1143  func (s *state) newValue0A(op ssa.Op, t *types.Type, aux ssa.Aux) *ssa.Value {
  1144  	return s.curBlock.NewValue0A(s.peekPos(), op, t, aux)
  1145  }
  1146  
  1147  // newValue0I adds a new value with no arguments and an auxint value to the current block.
  1148  func (s *state) newValue0I(op ssa.Op, t *types.Type, auxint int64) *ssa.Value {
  1149  	return s.curBlock.NewValue0I(s.peekPos(), op, t, auxint)
  1150  }
  1151  
  1152  // newValue1 adds a new value with one argument to the current block.
  1153  func (s *state) newValue1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1154  	return s.curBlock.NewValue1(s.peekPos(), op, t, arg)
  1155  }
  1156  
  1157  // newValue1A adds a new value with one argument and an aux value to the current block.
  1158  func (s *state) newValue1A(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value) *ssa.Value {
  1159  	return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
  1160  }
  1161  
  1162  // newValue1Apos adds a new value with one argument and an aux value to the current block.
  1163  // isStmt determines whether the created values may be a statement or not
  1164  // (i.e., false means never, yes means maybe).
  1165  func (s *state) newValue1Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value, isStmt bool) *ssa.Value {
  1166  	if isStmt {
  1167  		return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
  1168  	}
  1169  	return s.curBlock.NewValue1A(s.peekPos().WithNotStmt(), op, t, aux, arg)
  1170  }
  1171  
  1172  // newValue1I adds a new value with one argument and an auxint value to the current block.
  1173  func (s *state) newValue1I(op ssa.Op, t *types.Type, aux int64, arg *ssa.Value) *ssa.Value {
  1174  	return s.curBlock.NewValue1I(s.peekPos(), op, t, aux, arg)
  1175  }
  1176  
  1177  // newValue2 adds a new value with two arguments to the current block.
  1178  func (s *state) newValue2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1179  	return s.curBlock.NewValue2(s.peekPos(), op, t, arg0, arg1)
  1180  }
  1181  
  1182  // newValue2A adds a new value with two arguments and an aux value to the current block.
  1183  func (s *state) newValue2A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value) *ssa.Value {
  1184  	return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
  1185  }
  1186  
  1187  // newValue2Apos adds a new value with two arguments and an aux value to the current block.
  1188  // isStmt determines whether the created values may be a statement or not
  1189  // (i.e., false means never, yes means maybe).
  1190  func (s *state) newValue2Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value, isStmt bool) *ssa.Value {
  1191  	if isStmt {
  1192  		return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
  1193  	}
  1194  	return s.curBlock.NewValue2A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1)
  1195  }
  1196  
  1197  // newValue2I adds a new value with two arguments and an auxint value to the current block.
  1198  func (s *state) newValue2I(op ssa.Op, t *types.Type, aux int64, arg0, arg1 *ssa.Value) *ssa.Value {
  1199  	return s.curBlock.NewValue2I(s.peekPos(), op, t, aux, arg0, arg1)
  1200  }
  1201  
  1202  // newValue3 adds a new value with three arguments to the current block.
  1203  func (s *state) newValue3(op ssa.Op, t *types.Type, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1204  	return s.curBlock.NewValue3(s.peekPos(), op, t, arg0, arg1, arg2)
  1205  }
  1206  
  1207  // newValue3I adds a new value with three arguments and an auxint value to the current block.
  1208  func (s *state) newValue3I(op ssa.Op, t *types.Type, aux int64, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1209  	return s.curBlock.NewValue3I(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1210  }
  1211  
  1212  // newValue3A adds a new value with three arguments and an aux value to the current block.
  1213  func (s *state) newValue3A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1214  	return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1215  }
  1216  
  1217  // newValue3Apos adds a new value with three arguments and an aux value to the current block.
  1218  // isStmt determines whether the created values may be a statement or not
  1219  // (i.e., false means never, yes means maybe).
  1220  func (s *state) newValue3Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1, arg2 *ssa.Value, isStmt bool) *ssa.Value {
  1221  	if isStmt {
  1222  		return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1223  	}
  1224  	return s.curBlock.NewValue3A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1, arg2)
  1225  }
  1226  
  1227  // newValue4 adds a new value with four arguments to the current block.
  1228  func (s *state) newValue4(op ssa.Op, t *types.Type, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
  1229  	return s.curBlock.NewValue4(s.peekPos(), op, t, arg0, arg1, arg2, arg3)
  1230  }
  1231  
  1232  // newValue4I adds a new value with four arguments and an auxint value to the current block.
  1233  func (s *state) newValue4I(op ssa.Op, t *types.Type, aux int64, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
  1234  	return s.curBlock.NewValue4I(s.peekPos(), op, t, aux, arg0, arg1, arg2, arg3)
  1235  }
  1236  
  1237  func (s *state) entryBlock() *ssa.Block {
  1238  	b := s.f.Entry
  1239  	if base.Flag.N > 0 && s.curBlock != nil {
  1240  		// If optimizations are off, allocate in current block instead. Since with -N
  1241  		// we're not doing the CSE or tighten passes, putting lots of stuff in the
  1242  		// entry block leads to O(n^2) entries in the live value map during regalloc.
  1243  		// See issue 45897.
  1244  		b = s.curBlock
  1245  	}
  1246  	return b
  1247  }
  1248  
  1249  // entryNewValue0 adds a new value with no arguments to the entry block.
  1250  func (s *state) entryNewValue0(op ssa.Op, t *types.Type) *ssa.Value {
  1251  	return s.entryBlock().NewValue0(src.NoXPos, op, t)
  1252  }
  1253  
  1254  // entryNewValue0A adds a new value with no arguments and an aux value to the entry block.
  1255  func (s *state) entryNewValue0A(op ssa.Op, t *types.Type, aux ssa.Aux) *ssa.Value {
  1256  	return s.entryBlock().NewValue0A(src.NoXPos, op, t, aux)
  1257  }
  1258  
  1259  // entryNewValue1 adds a new value with one argument to the entry block.
  1260  func (s *state) entryNewValue1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1261  	return s.entryBlock().NewValue1(src.NoXPos, op, t, arg)
  1262  }
  1263  
  1264  // entryNewValue1I adds a new value with one argument and an auxint value to the entry block.
  1265  func (s *state) entryNewValue1I(op ssa.Op, t *types.Type, auxint int64, arg *ssa.Value) *ssa.Value {
  1266  	return s.entryBlock().NewValue1I(src.NoXPos, op, t, auxint, arg)
  1267  }
  1268  
  1269  // entryNewValue1A adds a new value with one argument and an aux value to the entry block.
  1270  func (s *state) entryNewValue1A(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value) *ssa.Value {
  1271  	return s.entryBlock().NewValue1A(src.NoXPos, op, t, aux, arg)
  1272  }
  1273  
  1274  // entryNewValue2 adds a new value with two arguments to the entry block.
  1275  func (s *state) entryNewValue2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1276  	return s.entryBlock().NewValue2(src.NoXPos, op, t, arg0, arg1)
  1277  }
  1278  
  1279  // entryNewValue2A adds a new value with two arguments and an aux value to the entry block.
  1280  func (s *state) entryNewValue2A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value) *ssa.Value {
  1281  	return s.entryBlock().NewValue2A(src.NoXPos, op, t, aux, arg0, arg1)
  1282  }
  1283  
  1284  // const* routines add a new const value to the entry block.
  1285  func (s *state) constSlice(t *types.Type) *ssa.Value {
  1286  	return s.f.ConstSlice(t)
  1287  }
  1288  func (s *state) constInterface(t *types.Type) *ssa.Value {
  1289  	return s.f.ConstInterface(t)
  1290  }
  1291  func (s *state) constNil(t *types.Type) *ssa.Value { return s.f.ConstNil(t) }
  1292  func (s *state) constEmptyString(t *types.Type) *ssa.Value {
  1293  	return s.f.ConstEmptyString(t)
  1294  }
  1295  func (s *state) constBool(c bool) *ssa.Value {
  1296  	return s.f.ConstBool(types.Types[types.TBOOL], c)
  1297  }
  1298  func (s *state) constInt8(t *types.Type, c int8) *ssa.Value {
  1299  	return s.f.ConstInt8(t, c)
  1300  }
  1301  func (s *state) constInt16(t *types.Type, c int16) *ssa.Value {
  1302  	return s.f.ConstInt16(t, c)
  1303  }
  1304  func (s *state) constInt32(t *types.Type, c int32) *ssa.Value {
  1305  	return s.f.ConstInt32(t, c)
  1306  }
  1307  func (s *state) constInt64(t *types.Type, c int64) *ssa.Value {
  1308  	return s.f.ConstInt64(t, c)
  1309  }
  1310  func (s *state) constFloat32(t *types.Type, c float64) *ssa.Value {
  1311  	return s.f.ConstFloat32(t, c)
  1312  }
  1313  func (s *state) constFloat64(t *types.Type, c float64) *ssa.Value {
  1314  	return s.f.ConstFloat64(t, c)
  1315  }
  1316  func (s *state) constInt(t *types.Type, c int64) *ssa.Value {
  1317  	if s.config.PtrSize == 8 {
  1318  		return s.constInt64(t, c)
  1319  	}
  1320  	if int64(int32(c)) != c {
  1321  		s.Fatalf("integer constant too big %d", c)
  1322  	}
  1323  	return s.constInt32(t, int32(c))
  1324  }
  1325  
  1326  // newValueOrSfCall* are wrappers around newValue*, which may create a call to a
  1327  // soft-float runtime function instead (when emitting soft-float code).
  1328  func (s *state) newValueOrSfCall1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1329  	if s.softFloat {
  1330  		if c, ok := s.sfcall(op, arg); ok {
  1331  			return c
  1332  		}
  1333  	}
  1334  	return s.newValue1(op, t, arg)
  1335  }
  1336  func (s *state) newValueOrSfCall2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1337  	if s.softFloat {
  1338  		if c, ok := s.sfcall(op, arg0, arg1); ok {
  1339  			return c
  1340  		}
  1341  	}
  1342  	return s.newValue2(op, t, arg0, arg1)
  1343  }
  1344  
  1345  type instrumentKind uint8
  1346  
  1347  const (
  1348  	instrumentRead = iota
  1349  	instrumentWrite
  1350  	instrumentMove
  1351  )
  1352  
  1353  func (s *state) instrument(t *types.Type, addr *ssa.Value, kind instrumentKind) {
  1354  	s.instrument2(t, addr, nil, kind)
  1355  }
  1356  
  1357  // instrumentFields instruments a read/write operation on addr.
  1358  // If it is instrumenting for MSAN or ASAN and t is a struct type, it instruments
  1359  // operation for each field, instead of for the whole struct.
  1360  func (s *state) instrumentFields(t *types.Type, addr *ssa.Value, kind instrumentKind) {
  1361  	if !(base.Flag.MSan || base.Flag.ASan) || !t.IsStruct() {
  1362  		s.instrument(t, addr, kind)
  1363  		return
  1364  	}
  1365  	for _, f := range t.Fields() {
  1366  		if f.Sym.IsBlank() {
  1367  			continue
  1368  		}
  1369  		offptr := s.newValue1I(ssa.OpOffPtr, types.NewPtr(f.Type), f.Offset, addr)
  1370  		s.instrumentFields(f.Type, offptr, kind)
  1371  	}
  1372  }
  1373  
  1374  func (s *state) instrumentMove(t *types.Type, dst, src *ssa.Value) {
  1375  	if base.Flag.MSan {
  1376  		s.instrument2(t, dst, src, instrumentMove)
  1377  	} else {
  1378  		s.instrument(t, src, instrumentRead)
  1379  		s.instrument(t, dst, instrumentWrite)
  1380  	}
  1381  }
  1382  
  1383  func (s *state) instrument2(t *types.Type, addr, addr2 *ssa.Value, kind instrumentKind) {
  1384  	if !s.instrumentMemory {
  1385  		return
  1386  	}
  1387  
  1388  	w := t.Size()
  1389  	if w == 0 {
  1390  		return // can't race on zero-sized things
  1391  	}
  1392  
  1393  	if ssa.IsSanitizerSafeAddr(addr) {
  1394  		return
  1395  	}
  1396  
  1397  	var fn *obj.LSym
  1398  	needWidth := false
  1399  
  1400  	if addr2 != nil && kind != instrumentMove {
  1401  		panic("instrument2: non-nil addr2 for non-move instrumentation")
  1402  	}
  1403  
  1404  	if base.Flag.MSan {
  1405  		switch kind {
  1406  		case instrumentRead:
  1407  			fn = ir.Syms.Msanread
  1408  		case instrumentWrite:
  1409  			fn = ir.Syms.Msanwrite
  1410  		case instrumentMove:
  1411  			fn = ir.Syms.Msanmove
  1412  		default:
  1413  			panic("unreachable")
  1414  		}
  1415  		needWidth = true
  1416  	} else if base.Flag.Race && t.NumComponents(types.CountBlankFields) > 1 {
  1417  		// for composite objects we have to write every address
  1418  		// because a write might happen to any subobject.
  1419  		// composites with only one element don't have subobjects, though.
  1420  		switch kind {
  1421  		case instrumentRead:
  1422  			fn = ir.Syms.Racereadrange
  1423  		case instrumentWrite:
  1424  			fn = ir.Syms.Racewriterange
  1425  		default:
  1426  			panic("unreachable")
  1427  		}
  1428  		needWidth = true
  1429  	} else if base.Flag.Race {
  1430  		// for non-composite objects we can write just the start
  1431  		// address, as any write must write the first byte.
  1432  		switch kind {
  1433  		case instrumentRead:
  1434  			fn = ir.Syms.Raceread
  1435  		case instrumentWrite:
  1436  			fn = ir.Syms.Racewrite
  1437  		default:
  1438  			panic("unreachable")
  1439  		}
  1440  	} else if base.Flag.ASan {
  1441  		switch kind {
  1442  		case instrumentRead:
  1443  			fn = ir.Syms.Asanread
  1444  		case instrumentWrite:
  1445  			fn = ir.Syms.Asanwrite
  1446  		default:
  1447  			panic("unreachable")
  1448  		}
  1449  		needWidth = true
  1450  	} else {
  1451  		panic("unreachable")
  1452  	}
  1453  
  1454  	args := []*ssa.Value{addr}
  1455  	if addr2 != nil {
  1456  		args = append(args, addr2)
  1457  	}
  1458  	if needWidth {
  1459  		args = append(args, s.constInt(types.Types[types.TUINTPTR], w))
  1460  	}
  1461  	s.rtcall(fn, true, nil, args...)
  1462  }
  1463  
  1464  func (s *state) load(t *types.Type, src *ssa.Value) *ssa.Value {
  1465  	s.instrumentFields(t, src, instrumentRead)
  1466  	return s.rawLoad(t, src)
  1467  }
  1468  
  1469  func (s *state) rawLoad(t *types.Type, src *ssa.Value) *ssa.Value {
  1470  	return s.newValue2(ssa.OpLoad, t, src, s.mem())
  1471  }
  1472  
  1473  func (s *state) store(t *types.Type, dst, val *ssa.Value) {
  1474  	s.vars[memVar] = s.newValue3A(ssa.OpStore, types.TypeMem, t, dst, val, s.mem())
  1475  }
  1476  
  1477  func (s *state) zero(t *types.Type, dst *ssa.Value) {
  1478  	s.instrument(t, dst, instrumentWrite)
  1479  	store := s.newValue2I(ssa.OpZero, types.TypeMem, t.Size(), dst, s.mem())
  1480  	store.Aux = t
  1481  	s.vars[memVar] = store
  1482  }
  1483  
  1484  func (s *state) move(t *types.Type, dst, src *ssa.Value) {
  1485  	s.moveWhichMayOverlap(t, dst, src, false)
  1486  }
  1487  func (s *state) moveWhichMayOverlap(t *types.Type, dst, src *ssa.Value, mayOverlap bool) {
  1488  	s.instrumentMove(t, dst, src)
  1489  	if mayOverlap && t.IsArray() && t.NumElem() > 1 && !ssa.IsInlinableMemmove(dst, src, t.Size(), s.f.Config) {
  1490  		// Normally, when moving Go values of type T from one location to another,
  1491  		// we don't need to worry about partial overlaps. The two Ts must either be
  1492  		// in disjoint (nonoverlapping) memory or in exactly the same location.
  1493  		// There are 2 cases where this isn't true:
  1494  		//  1) Using unsafe you can arrange partial overlaps.
  1495  		//  2) Since Go 1.17, you can use a cast from a slice to a ptr-to-array.
  1496  		//     https://go.dev/ref/spec#Conversions_from_slice_to_array_pointer
  1497  		//     This feature can be used to construct partial overlaps of array types.
  1498  		//       var a [3]int
  1499  		//       p := (*[2]int)(a[:])
  1500  		//       q := (*[2]int)(a[1:])
  1501  		//       *p = *q
  1502  		// We don't care about solving 1. Or at least, we haven't historically
  1503  		// and no one has complained.
  1504  		// For 2, we need to ensure that if there might be partial overlap,
  1505  		// then we can't use OpMove; we must use memmove instead.
  1506  		// (memmove handles partial overlap by copying in the correct
  1507  		// direction. OpMove does not.)
  1508  		//
  1509  		// Note that we have to be careful here not to introduce a call when
  1510  		// we're marshaling arguments to a call or unmarshaling results from a call.
  1511  		// Cases where this is happening must pass mayOverlap to false.
  1512  		// (Currently this only happens when unmarshaling results of a call.)
  1513  		if t.HasPointers() {
  1514  			s.rtcall(ir.Syms.Typedmemmove, true, nil, s.reflectType(t), dst, src)
  1515  			// We would have otherwise implemented this move with straightline code,
  1516  			// including a write barrier. Pretend we issue a write barrier here,
  1517  			// so that the write barrier tests work. (Otherwise they'd need to know
  1518  			// the details of IsInlineableMemmove.)
  1519  			s.curfn.SetWBPos(s.peekPos())
  1520  		} else {
  1521  			s.rtcall(ir.Syms.Memmove, true, nil, dst, src, s.constInt(types.Types[types.TUINTPTR], t.Size()))
  1522  		}
  1523  		ssa.LogLargeCopy(s.f.Name, s.peekPos(), t.Size())
  1524  		return
  1525  	}
  1526  	store := s.newValue3I(ssa.OpMove, types.TypeMem, t.Size(), dst, src, s.mem())
  1527  	store.Aux = t
  1528  	s.vars[memVar] = store
  1529  }
  1530  
  1531  // stmtList converts the statement list n to SSA and adds it to s.
  1532  func (s *state) stmtList(l ir.Nodes) {
  1533  	for _, n := range l {
  1534  		s.stmt(n)
  1535  	}
  1536  }
  1537  
  1538  // stmt converts the statement n to SSA and adds it to s.
  1539  func (s *state) stmt(n ir.Node) {
  1540  	s.pushLine(n.Pos())
  1541  	defer s.popLine()
  1542  
  1543  	// If s.curBlock is nil, and n isn't a label (which might have an associated goto somewhere),
  1544  	// then this code is dead. Stop here.
  1545  	if s.curBlock == nil && n.Op() != ir.OLABEL {
  1546  		return
  1547  	}
  1548  
  1549  	s.stmtList(n.Init())
  1550  	switch n.Op() {
  1551  
  1552  	case ir.OBLOCK:
  1553  		n := n.(*ir.BlockStmt)
  1554  		s.stmtList(n.List)
  1555  
  1556  	case ir.OFALL: // no-op
  1557  
  1558  	// Expression statements
  1559  	case ir.OCALLFUNC:
  1560  		n := n.(*ir.CallExpr)
  1561  		if ir.IsIntrinsicCall(n) {
  1562  			s.intrinsicCall(n)
  1563  			return
  1564  		}
  1565  		fallthrough
  1566  
  1567  	case ir.OCALLINTER:
  1568  		n := n.(*ir.CallExpr)
  1569  		s.callResult(n, callNormal)
  1570  		if n.Op() == ir.OCALLFUNC && n.Fun.Op() == ir.ONAME && n.Fun.(*ir.Name).Class == ir.PFUNC {
  1571  			if fn := n.Fun.Sym().Name; base.Flag.CompilingRuntime && fn == "throw" ||
  1572  				n.Fun.Sym().Pkg == ir.Pkgs.Runtime &&
  1573  					(fn == "throwinit" || fn == "gopanic" || fn == "panicwrap" || fn == "block" ||
  1574  						fn == "panicmakeslicelen" || fn == "panicmakeslicecap" || fn == "panicunsafeslicelen" ||
  1575  						fn == "panicunsafeslicenilptr" || fn == "panicunsafestringlen" || fn == "panicunsafestringnilptr" ||
  1576  						fn == "panicrangestate") {
  1577  				m := s.mem()
  1578  				b := s.endBlock()
  1579  				b.Kind = ssa.BlockExit
  1580  				b.SetControl(m)
  1581  				// TODO: never rewrite OPANIC to OCALLFUNC in the
  1582  				// first place. Need to wait until all backends
  1583  				// go through SSA.
  1584  			}
  1585  		}
  1586  	case ir.ODEFER:
  1587  		n := n.(*ir.GoDeferStmt)
  1588  		if base.Debug.Defer > 0 {
  1589  			var defertype string
  1590  			if s.hasOpenDefers {
  1591  				defertype = "open-coded"
  1592  			} else if n.Esc() == ir.EscNever {
  1593  				defertype = "stack-allocated"
  1594  			} else {
  1595  				defertype = "heap-allocated"
  1596  			}
  1597  			base.WarnfAt(n.Pos(), "%s defer", defertype)
  1598  		}
  1599  		if s.hasOpenDefers {
  1600  			s.openDeferRecord(n.Call.(*ir.CallExpr))
  1601  		} else {
  1602  			d := callDefer
  1603  			if n.Esc() == ir.EscNever && n.DeferAt == nil {
  1604  				d = callDeferStack
  1605  			}
  1606  			s.call(n.Call.(*ir.CallExpr), d, false, n.DeferAt)
  1607  		}
  1608  	case ir.OGO:
  1609  		n := n.(*ir.GoDeferStmt)
  1610  		s.callResult(n.Call.(*ir.CallExpr), callGo)
  1611  
  1612  	case ir.OAS2DOTTYPE:
  1613  		n := n.(*ir.AssignListStmt)
  1614  		var res, resok *ssa.Value
  1615  		if n.Rhs[0].Op() == ir.ODOTTYPE2 {
  1616  			res, resok = s.dottype(n.Rhs[0].(*ir.TypeAssertExpr), true)
  1617  		} else {
  1618  			res, resok = s.dynamicDottype(n.Rhs[0].(*ir.DynamicTypeAssertExpr), true)
  1619  		}
  1620  		deref := false
  1621  		if !ssa.CanSSA(n.Rhs[0].Type()) {
  1622  			if res.Op != ssa.OpLoad {
  1623  				s.Fatalf("dottype of non-load")
  1624  			}
  1625  			mem := s.mem()
  1626  			if res.Args[1] != mem {
  1627  				s.Fatalf("memory no longer live from 2-result dottype load")
  1628  			}
  1629  			deref = true
  1630  			res = res.Args[0]
  1631  		}
  1632  		s.assign(n.Lhs[0], res, deref, 0)
  1633  		s.assign(n.Lhs[1], resok, false, 0)
  1634  		return
  1635  
  1636  	case ir.OAS2FUNC:
  1637  		// We come here only when it is an intrinsic call returning two values.
  1638  		n := n.(*ir.AssignListStmt)
  1639  		call := n.Rhs[0].(*ir.CallExpr)
  1640  		if !ir.IsIntrinsicCall(call) {
  1641  			s.Fatalf("non-intrinsic AS2FUNC not expanded %v", call)
  1642  		}
  1643  		v := s.intrinsicCall(call)
  1644  		v1 := s.newValue1(ssa.OpSelect0, n.Lhs[0].Type(), v)
  1645  		v2 := s.newValue1(ssa.OpSelect1, n.Lhs[1].Type(), v)
  1646  		s.assign(n.Lhs[0], v1, false, 0)
  1647  		s.assign(n.Lhs[1], v2, false, 0)
  1648  		return
  1649  
  1650  	case ir.ODCL:
  1651  		n := n.(*ir.Decl)
  1652  		if v := n.X; v.Esc() == ir.EscHeap {
  1653  			s.newHeapaddr(v)
  1654  		}
  1655  
  1656  	case ir.OLABEL:
  1657  		n := n.(*ir.LabelStmt)
  1658  		sym := n.Label
  1659  		if sym.IsBlank() {
  1660  			// Nothing to do because the label isn't targetable. See issue 52278.
  1661  			break
  1662  		}
  1663  		lab := s.label(sym)
  1664  
  1665  		// The label might already have a target block via a goto.
  1666  		if lab.target == nil {
  1667  			lab.target = s.f.NewBlock(ssa.BlockPlain)
  1668  		}
  1669  
  1670  		// Go to that label.
  1671  		// (We pretend "label:" is preceded by "goto label", unless the predecessor is unreachable.)
  1672  		if s.curBlock != nil {
  1673  			b := s.endBlock()
  1674  			b.AddEdgeTo(lab.target)
  1675  		}
  1676  		s.startBlock(lab.target)
  1677  
  1678  	case ir.OGOTO:
  1679  		n := n.(*ir.BranchStmt)
  1680  		sym := n.Label
  1681  
  1682  		lab := s.label(sym)
  1683  		if lab.target == nil {
  1684  			lab.target = s.f.NewBlock(ssa.BlockPlain)
  1685  		}
  1686  
  1687  		b := s.endBlock()
  1688  		b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
  1689  		b.AddEdgeTo(lab.target)
  1690  
  1691  	case ir.OAS:
  1692  		n := n.(*ir.AssignStmt)
  1693  		if n.X == n.Y && n.X.Op() == ir.ONAME {
  1694  			// An x=x assignment. No point in doing anything
  1695  			// here. In addition, skipping this assignment
  1696  			// prevents generating:
  1697  			//   VARDEF x
  1698  			//   COPY x -> x
  1699  			// which is bad because x is incorrectly considered
  1700  			// dead before the vardef. See issue #14904.
  1701  			return
  1702  		}
  1703  
  1704  		// mayOverlap keeps track of whether the LHS and RHS might
  1705  		// refer to partially overlapping memory. Partial overlapping can
  1706  		// only happen for arrays, see the comment in moveWhichMayOverlap.
  1707  		//
  1708  		// If both sides of the assignment are not dereferences, then partial
  1709  		// overlap can't happen. Partial overlap can only occur only when the
  1710  		// arrays referenced are strictly smaller parts of the same base array.
  1711  		// If one side of the assignment is a full array, then partial overlap
  1712  		// can't happen. (The arrays are either disjoint or identical.)
  1713  		mayOverlap := n.X.Op() == ir.ODEREF && (n.Y != nil && n.Y.Op() == ir.ODEREF)
  1714  		if n.Y != nil && n.Y.Op() == ir.ODEREF {
  1715  			p := n.Y.(*ir.StarExpr).X
  1716  			for p.Op() == ir.OCONVNOP {
  1717  				p = p.(*ir.ConvExpr).X
  1718  			}
  1719  			if p.Op() == ir.OSPTR && p.(*ir.UnaryExpr).X.Type().IsString() {
  1720  				// Pointer fields of strings point to unmodifiable memory.
  1721  				// That memory can't overlap with the memory being written.
  1722  				mayOverlap = false
  1723  			}
  1724  		}
  1725  
  1726  		// Evaluate RHS.
  1727  		rhs := n.Y
  1728  		if rhs != nil {
  1729  			switch rhs.Op() {
  1730  			case ir.OSTRUCTLIT, ir.OARRAYLIT, ir.OSLICELIT:
  1731  				// All literals with nonzero fields have already been
  1732  				// rewritten during walk. Any that remain are just T{}
  1733  				// or equivalents. Use the zero value.
  1734  				if !ir.IsZero(rhs) {
  1735  					s.Fatalf("literal with nonzero value in SSA: %v", rhs)
  1736  				}
  1737  				rhs = nil
  1738  			case ir.OAPPEND:
  1739  				rhs := rhs.(*ir.CallExpr)
  1740  				// Check whether we're writing the result of an append back to the same slice.
  1741  				// If so, we handle it specially to avoid write barriers on the fast
  1742  				// (non-growth) path.
  1743  				if !ir.SameSafeExpr(n.X, rhs.Args[0]) || base.Flag.N != 0 {
  1744  					break
  1745  				}
  1746  				// If the slice can be SSA'd, it'll be on the stack,
  1747  				// so there will be no write barriers,
  1748  				// so there's no need to attempt to prevent them.
  1749  				if s.canSSA(n.X) {
  1750  					if base.Debug.Append > 0 { // replicating old diagnostic message
  1751  						base.WarnfAt(n.Pos(), "append: len-only update (in local slice)")
  1752  					}
  1753  					break
  1754  				}
  1755  				if base.Debug.Append > 0 {
  1756  					base.WarnfAt(n.Pos(), "append: len-only update")
  1757  				}
  1758  				s.append(rhs, true)
  1759  				return
  1760  			}
  1761  		}
  1762  
  1763  		if ir.IsBlank(n.X) {
  1764  			// _ = rhs
  1765  			// Just evaluate rhs for side-effects.
  1766  			if rhs != nil {
  1767  				s.expr(rhs)
  1768  			}
  1769  			return
  1770  		}
  1771  
  1772  		var t *types.Type
  1773  		if n.Y != nil {
  1774  			t = n.Y.Type()
  1775  		} else {
  1776  			t = n.X.Type()
  1777  		}
  1778  
  1779  		var r *ssa.Value
  1780  		deref := !ssa.CanSSA(t)
  1781  		if deref {
  1782  			if rhs == nil {
  1783  				r = nil // Signal assign to use OpZero.
  1784  			} else {
  1785  				r = s.addr(rhs)
  1786  			}
  1787  		} else {
  1788  			if rhs == nil {
  1789  				r = s.zeroVal(t)
  1790  			} else {
  1791  				r = s.expr(rhs)
  1792  			}
  1793  		}
  1794  
  1795  		var skip skipMask
  1796  		if rhs != nil && (rhs.Op() == ir.OSLICE || rhs.Op() == ir.OSLICE3 || rhs.Op() == ir.OSLICESTR) && ir.SameSafeExpr(rhs.(*ir.SliceExpr).X, n.X) {
  1797  			// We're assigning a slicing operation back to its source.
  1798  			// Don't write back fields we aren't changing. See issue #14855.
  1799  			rhs := rhs.(*ir.SliceExpr)
  1800  			i, j, k := rhs.Low, rhs.High, rhs.Max
  1801  			if i != nil && (i.Op() == ir.OLITERAL && i.Val().Kind() == constant.Int && ir.Int64Val(i) == 0) {
  1802  				// [0:...] is the same as [:...]
  1803  				i = nil
  1804  			}
  1805  			// TODO: detect defaults for len/cap also.
  1806  			// Currently doesn't really work because (*p)[:len(*p)] appears here as:
  1807  			//    tmp = len(*p)
  1808  			//    (*p)[:tmp]
  1809  			// if j != nil && (j.Op == OLEN && SameSafeExpr(j.Left, n.Left)) {
  1810  			//      j = nil
  1811  			// }
  1812  			// if k != nil && (k.Op == OCAP && SameSafeExpr(k.Left, n.Left)) {
  1813  			//      k = nil
  1814  			// }
  1815  			if i == nil {
  1816  				skip |= skipPtr
  1817  				if j == nil {
  1818  					skip |= skipLen
  1819  				}
  1820  				if k == nil {
  1821  					skip |= skipCap
  1822  				}
  1823  			}
  1824  		}
  1825  
  1826  		s.assignWhichMayOverlap(n.X, r, deref, skip, mayOverlap)
  1827  
  1828  	case ir.OIF:
  1829  		n := n.(*ir.IfStmt)
  1830  		if ir.IsConst(n.Cond, constant.Bool) {
  1831  			s.stmtList(n.Cond.Init())
  1832  			if ir.BoolVal(n.Cond) {
  1833  				s.stmtList(n.Body)
  1834  			} else {
  1835  				s.stmtList(n.Else)
  1836  			}
  1837  			break
  1838  		}
  1839  
  1840  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  1841  		var likely int8
  1842  		if n.Likely {
  1843  			likely = 1
  1844  		}
  1845  		var bThen *ssa.Block
  1846  		if len(n.Body) != 0 {
  1847  			bThen = s.f.NewBlock(ssa.BlockPlain)
  1848  		} else {
  1849  			bThen = bEnd
  1850  		}
  1851  		var bElse *ssa.Block
  1852  		if len(n.Else) != 0 {
  1853  			bElse = s.f.NewBlock(ssa.BlockPlain)
  1854  		} else {
  1855  			bElse = bEnd
  1856  		}
  1857  		s.condBranch(n.Cond, bThen, bElse, likely)
  1858  
  1859  		if len(n.Body) != 0 {
  1860  			s.startBlock(bThen)
  1861  			s.stmtList(n.Body)
  1862  			if b := s.endBlock(); b != nil {
  1863  				b.AddEdgeTo(bEnd)
  1864  			}
  1865  		}
  1866  		if len(n.Else) != 0 {
  1867  			s.startBlock(bElse)
  1868  			s.stmtList(n.Else)
  1869  			if b := s.endBlock(); b != nil {
  1870  				b.AddEdgeTo(bEnd)
  1871  			}
  1872  		}
  1873  		s.startBlock(bEnd)
  1874  
  1875  	case ir.ORETURN:
  1876  		n := n.(*ir.ReturnStmt)
  1877  		s.stmtList(n.Results)
  1878  		b := s.exit()
  1879  		b.Pos = s.lastPos.WithIsStmt()
  1880  
  1881  	case ir.OTAILCALL:
  1882  		n := n.(*ir.TailCallStmt)
  1883  		s.callResult(n.Call, callTail)
  1884  		call := s.mem()
  1885  		b := s.endBlock()
  1886  		b.Kind = ssa.BlockRetJmp // could use BlockExit. BlockRetJmp is mostly for clarity.
  1887  		b.SetControl(call)
  1888  
  1889  	case ir.OCONTINUE, ir.OBREAK:
  1890  		n := n.(*ir.BranchStmt)
  1891  		var to *ssa.Block
  1892  		if n.Label == nil {
  1893  			// plain break/continue
  1894  			switch n.Op() {
  1895  			case ir.OCONTINUE:
  1896  				to = s.continueTo
  1897  			case ir.OBREAK:
  1898  				to = s.breakTo
  1899  			}
  1900  		} else {
  1901  			// labeled break/continue; look up the target
  1902  			sym := n.Label
  1903  			lab := s.label(sym)
  1904  			switch n.Op() {
  1905  			case ir.OCONTINUE:
  1906  				to = lab.continueTarget
  1907  			case ir.OBREAK:
  1908  				to = lab.breakTarget
  1909  			}
  1910  		}
  1911  
  1912  		b := s.endBlock()
  1913  		b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
  1914  		b.AddEdgeTo(to)
  1915  
  1916  	case ir.OFOR:
  1917  		// OFOR: for Ninit; Left; Right { Nbody }
  1918  		// cond (Left); body (Nbody); incr (Right)
  1919  		n := n.(*ir.ForStmt)
  1920  		base.Assert(!n.DistinctVars) // Should all be rewritten before escape analysis
  1921  		bCond := s.f.NewBlock(ssa.BlockPlain)
  1922  		bBody := s.f.NewBlock(ssa.BlockPlain)
  1923  		bIncr := s.f.NewBlock(ssa.BlockPlain)
  1924  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  1925  
  1926  		// ensure empty for loops have correct position; issue #30167
  1927  		bBody.Pos = n.Pos()
  1928  
  1929  		// first, jump to condition test
  1930  		b := s.endBlock()
  1931  		b.AddEdgeTo(bCond)
  1932  
  1933  		// generate code to test condition
  1934  		s.startBlock(bCond)
  1935  		if n.Cond != nil {
  1936  			s.condBranch(n.Cond, bBody, bEnd, 1)
  1937  		} else {
  1938  			b := s.endBlock()
  1939  			b.Kind = ssa.BlockPlain
  1940  			b.AddEdgeTo(bBody)
  1941  		}
  1942  
  1943  		// set up for continue/break in body
  1944  		prevContinue := s.continueTo
  1945  		prevBreak := s.breakTo
  1946  		s.continueTo = bIncr
  1947  		s.breakTo = bEnd
  1948  		var lab *ssaLabel
  1949  		if sym := n.Label; sym != nil {
  1950  			// labeled for loop
  1951  			lab = s.label(sym)
  1952  			lab.continueTarget = bIncr
  1953  			lab.breakTarget = bEnd
  1954  		}
  1955  
  1956  		// generate body
  1957  		s.startBlock(bBody)
  1958  		s.stmtList(n.Body)
  1959  
  1960  		// tear down continue/break
  1961  		s.continueTo = prevContinue
  1962  		s.breakTo = prevBreak
  1963  		if lab != nil {
  1964  			lab.continueTarget = nil
  1965  			lab.breakTarget = nil
  1966  		}
  1967  
  1968  		// done with body, goto incr
  1969  		if b := s.endBlock(); b != nil {
  1970  			b.AddEdgeTo(bIncr)
  1971  		}
  1972  
  1973  		// generate incr
  1974  		s.startBlock(bIncr)
  1975  		if n.Post != nil {
  1976  			s.stmt(n.Post)
  1977  		}
  1978  		if b := s.endBlock(); b != nil {
  1979  			b.AddEdgeTo(bCond)
  1980  			// It can happen that bIncr ends in a block containing only VARKILL,
  1981  			// and that muddles the debugging experience.
  1982  			if b.Pos == src.NoXPos {
  1983  				b.Pos = bCond.Pos
  1984  			}
  1985  		}
  1986  
  1987  		s.startBlock(bEnd)
  1988  
  1989  	case ir.OSWITCH, ir.OSELECT:
  1990  		// These have been mostly rewritten by the front end into their Nbody fields.
  1991  		// Our main task is to correctly hook up any break statements.
  1992  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  1993  
  1994  		prevBreak := s.breakTo
  1995  		s.breakTo = bEnd
  1996  		var sym *types.Sym
  1997  		var body ir.Nodes
  1998  		if n.Op() == ir.OSWITCH {
  1999  			n := n.(*ir.SwitchStmt)
  2000  			sym = n.Label
  2001  			body = n.Compiled
  2002  		} else {
  2003  			n := n.(*ir.SelectStmt)
  2004  			sym = n.Label
  2005  			body = n.Compiled
  2006  		}
  2007  
  2008  		var lab *ssaLabel
  2009  		if sym != nil {
  2010  			// labeled
  2011  			lab = s.label(sym)
  2012  			lab.breakTarget = bEnd
  2013  		}
  2014  
  2015  		// generate body code
  2016  		s.stmtList(body)
  2017  
  2018  		s.breakTo = prevBreak
  2019  		if lab != nil {
  2020  			lab.breakTarget = nil
  2021  		}
  2022  
  2023  		// walk adds explicit OBREAK nodes to the end of all reachable code paths.
  2024  		// If we still have a current block here, then mark it unreachable.
  2025  		if s.curBlock != nil {
  2026  			m := s.mem()
  2027  			b := s.endBlock()
  2028  			b.Kind = ssa.BlockExit
  2029  			b.SetControl(m)
  2030  		}
  2031  		s.startBlock(bEnd)
  2032  
  2033  	case ir.OJUMPTABLE:
  2034  		n := n.(*ir.JumpTableStmt)
  2035  
  2036  		// Make blocks we'll need.
  2037  		jt := s.f.NewBlock(ssa.BlockJumpTable)
  2038  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  2039  
  2040  		// The only thing that needs evaluating is the index we're looking up.
  2041  		idx := s.expr(n.Idx)
  2042  		unsigned := idx.Type.IsUnsigned()
  2043  
  2044  		// Extend so we can do everything in uintptr arithmetic.
  2045  		t := types.Types[types.TUINTPTR]
  2046  		idx = s.conv(nil, idx, idx.Type, t)
  2047  
  2048  		// The ending condition for the current block decides whether we'll use
  2049  		// the jump table at all.
  2050  		// We check that min <= idx <= max and jump around the jump table
  2051  		// if that test fails.
  2052  		// We implement min <= idx <= max with 0 <= idx-min <= max-min, because
  2053  		// we'll need idx-min anyway as the control value for the jump table.
  2054  		var min, max uint64
  2055  		if unsigned {
  2056  			min, _ = constant.Uint64Val(n.Cases[0])
  2057  			max, _ = constant.Uint64Val(n.Cases[len(n.Cases)-1])
  2058  		} else {
  2059  			mn, _ := constant.Int64Val(n.Cases[0])
  2060  			mx, _ := constant.Int64Val(n.Cases[len(n.Cases)-1])
  2061  			min = uint64(mn)
  2062  			max = uint64(mx)
  2063  		}
  2064  		// Compare idx-min with max-min, to see if we can use the jump table.
  2065  		idx = s.newValue2(s.ssaOp(ir.OSUB, t), t, idx, s.uintptrConstant(min))
  2066  		width := s.uintptrConstant(max - min)
  2067  		cmp := s.newValue2(s.ssaOp(ir.OLE, t), types.Types[types.TBOOL], idx, width)
  2068  		b := s.endBlock()
  2069  		b.Kind = ssa.BlockIf
  2070  		b.SetControl(cmp)
  2071  		b.AddEdgeTo(jt)             // in range - use jump table
  2072  		b.AddEdgeTo(bEnd)           // out of range - no case in the jump table will trigger
  2073  		b.Likely = ssa.BranchLikely // TODO: assumes missing the table entirely is unlikely. True?
  2074  
  2075  		// Build jump table block.
  2076  		s.startBlock(jt)
  2077  		jt.Pos = n.Pos()
  2078  		if base.Flag.Cfg.SpectreIndex {
  2079  			idx = s.newValue2(ssa.OpSpectreSliceIndex, t, idx, width)
  2080  		}
  2081  		jt.SetControl(idx)
  2082  
  2083  		// Figure out where we should go for each index in the table.
  2084  		table := make([]*ssa.Block, max-min+1)
  2085  		for i := range table {
  2086  			table[i] = bEnd // default target
  2087  		}
  2088  		for i := range n.Targets {
  2089  			c := n.Cases[i]
  2090  			lab := s.label(n.Targets[i])
  2091  			if lab.target == nil {
  2092  				lab.target = s.f.NewBlock(ssa.BlockPlain)
  2093  			}
  2094  			var val uint64
  2095  			if unsigned {
  2096  				val, _ = constant.Uint64Val(c)
  2097  			} else {
  2098  				vl, _ := constant.Int64Val(c)
  2099  				val = uint64(vl)
  2100  			}
  2101  			// Overwrite the default target.
  2102  			table[val-min] = lab.target
  2103  		}
  2104  		for _, t := range table {
  2105  			jt.AddEdgeTo(t)
  2106  		}
  2107  		s.endBlock()
  2108  
  2109  		s.startBlock(bEnd)
  2110  
  2111  	case ir.OINTERFACESWITCH:
  2112  		n := n.(*ir.InterfaceSwitchStmt)
  2113  		typs := s.f.Config.Types
  2114  
  2115  		t := s.expr(n.RuntimeType)
  2116  		h := s.expr(n.Hash)
  2117  		d := s.newValue1A(ssa.OpAddr, typs.BytePtr, n.Descriptor, s.sb)
  2118  
  2119  		// Check the cache first.
  2120  		var merge *ssa.Block
  2121  		if base.Flag.N == 0 && rtabi.UseInterfaceSwitchCache(Arch.LinkArch.Family) {
  2122  			// Note: we can only use the cache if we have the right atomic load instruction.
  2123  			// Double-check that here.
  2124  			if intrinsics.lookup(Arch.LinkArch.Arch, "internal/runtime/atomic", "Loadp") == nil {
  2125  				s.Fatalf("atomic load not available")
  2126  			}
  2127  			merge = s.f.NewBlock(ssa.BlockPlain)
  2128  			cacheHit := s.f.NewBlock(ssa.BlockPlain)
  2129  			cacheMiss := s.f.NewBlock(ssa.BlockPlain)
  2130  			loopHead := s.f.NewBlock(ssa.BlockPlain)
  2131  			loopBody := s.f.NewBlock(ssa.BlockPlain)
  2132  
  2133  			// Pick right size ops.
  2134  			var mul, and, add, zext ssa.Op
  2135  			if s.config.PtrSize == 4 {
  2136  				mul = ssa.OpMul32
  2137  				and = ssa.OpAnd32
  2138  				add = ssa.OpAdd32
  2139  				zext = ssa.OpCopy
  2140  			} else {
  2141  				mul = ssa.OpMul64
  2142  				and = ssa.OpAnd64
  2143  				add = ssa.OpAdd64
  2144  				zext = ssa.OpZeroExt32to64
  2145  			}
  2146  
  2147  			// Load cache pointer out of descriptor, with an atomic load so
  2148  			// we ensure that we see a fully written cache.
  2149  			atomicLoad := s.newValue2(ssa.OpAtomicLoadPtr, types.NewTuple(typs.BytePtr, types.TypeMem), d, s.mem())
  2150  			cache := s.newValue1(ssa.OpSelect0, typs.BytePtr, atomicLoad)
  2151  			s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, atomicLoad)
  2152  
  2153  			// Initialize hash variable.
  2154  			s.vars[hashVar] = s.newValue1(zext, typs.Uintptr, h)
  2155  
  2156  			// Load mask from cache.
  2157  			mask := s.newValue2(ssa.OpLoad, typs.Uintptr, cache, s.mem())
  2158  			// Jump to loop head.
  2159  			b := s.endBlock()
  2160  			b.AddEdgeTo(loopHead)
  2161  
  2162  			// At loop head, get pointer to the cache entry.
  2163  			//   e := &cache.Entries[hash&mask]
  2164  			s.startBlock(loopHead)
  2165  			entries := s.newValue2(ssa.OpAddPtr, typs.UintptrPtr, cache, s.uintptrConstant(uint64(s.config.PtrSize)))
  2166  			idx := s.newValue2(and, typs.Uintptr, s.variable(hashVar, typs.Uintptr), mask)
  2167  			idx = s.newValue2(mul, typs.Uintptr, idx, s.uintptrConstant(uint64(3*s.config.PtrSize)))
  2168  			e := s.newValue2(ssa.OpAddPtr, typs.UintptrPtr, entries, idx)
  2169  			//   hash++
  2170  			s.vars[hashVar] = s.newValue2(add, typs.Uintptr, s.variable(hashVar, typs.Uintptr), s.uintptrConstant(1))
  2171  
  2172  			// Look for a cache hit.
  2173  			//   if e.Typ == t { goto hit }
  2174  			eTyp := s.newValue2(ssa.OpLoad, typs.Uintptr, e, s.mem())
  2175  			cmp1 := s.newValue2(ssa.OpEqPtr, typs.Bool, t, eTyp)
  2176  			b = s.endBlock()
  2177  			b.Kind = ssa.BlockIf
  2178  			b.SetControl(cmp1)
  2179  			b.AddEdgeTo(cacheHit)
  2180  			b.AddEdgeTo(loopBody)
  2181  
  2182  			// Look for an empty entry, the tombstone for this hash table.
  2183  			//   if e.Typ == nil { goto miss }
  2184  			s.startBlock(loopBody)
  2185  			cmp2 := s.newValue2(ssa.OpEqPtr, typs.Bool, eTyp, s.constNil(typs.BytePtr))
  2186  			b = s.endBlock()
  2187  			b.Kind = ssa.BlockIf
  2188  			b.SetControl(cmp2)
  2189  			b.AddEdgeTo(cacheMiss)
  2190  			b.AddEdgeTo(loopHead)
  2191  
  2192  			// On a hit, load the data fields of the cache entry.
  2193  			//   Case = e.Case
  2194  			//   Itab = e.Itab
  2195  			s.startBlock(cacheHit)
  2196  			eCase := s.newValue2(ssa.OpLoad, typs.Int, s.newValue1I(ssa.OpOffPtr, typs.IntPtr, s.config.PtrSize, e), s.mem())
  2197  			eItab := s.newValue2(ssa.OpLoad, typs.BytePtr, s.newValue1I(ssa.OpOffPtr, typs.BytePtrPtr, 2*s.config.PtrSize, e), s.mem())
  2198  			s.assign(n.Case, eCase, false, 0)
  2199  			s.assign(n.Itab, eItab, false, 0)
  2200  			b = s.endBlock()
  2201  			b.AddEdgeTo(merge)
  2202  
  2203  			// On a miss, call into the runtime to get the answer.
  2204  			s.startBlock(cacheMiss)
  2205  		}
  2206  
  2207  		r := s.rtcall(ir.Syms.InterfaceSwitch, true, []*types.Type{typs.Int, typs.BytePtr}, d, t)
  2208  		s.assign(n.Case, r[0], false, 0)
  2209  		s.assign(n.Itab, r[1], false, 0)
  2210  
  2211  		if merge != nil {
  2212  			// Cache hits merge in here.
  2213  			b := s.endBlock()
  2214  			b.Kind = ssa.BlockPlain
  2215  			b.AddEdgeTo(merge)
  2216  			s.startBlock(merge)
  2217  		}
  2218  
  2219  	case ir.OCHECKNIL:
  2220  		n := n.(*ir.UnaryExpr)
  2221  		p := s.expr(n.X)
  2222  		_ = s.nilCheck(p)
  2223  		// TODO: check that throwing away the nilcheck result is ok.
  2224  
  2225  	case ir.OINLMARK:
  2226  		n := n.(*ir.InlineMarkStmt)
  2227  		s.newValue1I(ssa.OpInlMark, types.TypeVoid, n.Index, s.mem())
  2228  
  2229  	default:
  2230  		s.Fatalf("unhandled stmt %v", n.Op())
  2231  	}
  2232  }
  2233  
  2234  // If true, share as many open-coded defer exits as possible (with the downside of
  2235  // worse line-number information)
  2236  const shareDeferExits = false
  2237  
  2238  // exit processes any code that needs to be generated just before returning.
  2239  // It returns a BlockRet block that ends the control flow. Its control value
  2240  // will be set to the final memory state.
  2241  func (s *state) exit() *ssa.Block {
  2242  	if s.hasdefer {
  2243  		if s.hasOpenDefers {
  2244  			if shareDeferExits && s.lastDeferExit != nil && len(s.openDefers) == s.lastDeferCount {
  2245  				if s.curBlock.Kind != ssa.BlockPlain {
  2246  					panic("Block for an exit should be BlockPlain")
  2247  				}
  2248  				s.curBlock.AddEdgeTo(s.lastDeferExit)
  2249  				s.endBlock()
  2250  				return s.lastDeferFinalBlock
  2251  			}
  2252  			s.openDeferExit()
  2253  		} else {
  2254  			// Shared deferreturn is assigned the "last" position in the function.
  2255  			// The linker picks the first deferreturn call it sees, so this is
  2256  			// the only sensible "shared" place.
  2257  			// To not-share deferreturn, the protocol would need to be changed
  2258  			// so that the call to deferproc-etc would receive the PC offset from
  2259  			// the return PC, and the runtime would need to use that instead of
  2260  			// the deferreturn retrieved from the pcln information.
  2261  			// opendefers would remain a problem, however.
  2262  			s.pushLine(s.curfn.Endlineno)
  2263  			s.rtcall(ir.Syms.Deferreturn, true, nil)
  2264  			s.popLine()
  2265  		}
  2266  	}
  2267  
  2268  	// Do actual return.
  2269  	// These currently turn into self-copies (in many cases).
  2270  	resultFields := s.curfn.Type().Results()
  2271  	results := make([]*ssa.Value, len(resultFields)+1, len(resultFields)+1)
  2272  	// Store SSAable and heap-escaped PPARAMOUT variables back to stack locations.
  2273  	for i, f := range resultFields {
  2274  		n := f.Nname.(*ir.Name)
  2275  		if s.canSSA(n) { // result is in some SSA variable
  2276  			if !n.IsOutputParamInRegisters() && n.Type().HasPointers() {
  2277  				// We are about to store to the result slot.
  2278  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
  2279  			}
  2280  			results[i] = s.variable(n, n.Type())
  2281  		} else if !n.OnStack() { // result is actually heap allocated
  2282  			// We are about to copy the in-heap result to the result slot.
  2283  			if n.Type().HasPointers() {
  2284  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
  2285  			}
  2286  			ha := s.expr(n.Heapaddr)
  2287  			s.instrumentFields(n.Type(), ha, instrumentRead)
  2288  			results[i] = s.newValue2(ssa.OpDereference, n.Type(), ha, s.mem())
  2289  		} else { // result is not SSA-able; not escaped, so not on heap, but too large for SSA.
  2290  			// Before register ABI this ought to be a self-move, home=dest,
  2291  			// With register ABI, it's still a self-move if parameter is on stack (i.e., too big or overflowed)
  2292  			// No VarDef, as the result slot is already holding live value.
  2293  			results[i] = s.newValue2(ssa.OpDereference, n.Type(), s.addr(n), s.mem())
  2294  		}
  2295  	}
  2296  
  2297  	// In -race mode, we need to call racefuncexit.
  2298  	// Note: This has to happen after we load any heap-allocated results,
  2299  	// otherwise races will be attributed to the caller instead.
  2300  	if s.instrumentEnterExit {
  2301  		s.rtcall(ir.Syms.Racefuncexit, true, nil)
  2302  	}
  2303  
  2304  	results[len(results)-1] = s.mem()
  2305  	m := s.newValue0(ssa.OpMakeResult, s.f.OwnAux.LateExpansionResultType())
  2306  	m.AddArgs(results...)
  2307  
  2308  	b := s.endBlock()
  2309  	b.Kind = ssa.BlockRet
  2310  	b.SetControl(m)
  2311  	if s.hasdefer && s.hasOpenDefers {
  2312  		s.lastDeferFinalBlock = b
  2313  	}
  2314  	return b
  2315  }
  2316  
  2317  type opAndType struct {
  2318  	op    ir.Op
  2319  	etype types.Kind
  2320  }
  2321  
  2322  var opToSSA = map[opAndType]ssa.Op{
  2323  	{ir.OADD, types.TINT8}:    ssa.OpAdd8,
  2324  	{ir.OADD, types.TUINT8}:   ssa.OpAdd8,
  2325  	{ir.OADD, types.TINT16}:   ssa.OpAdd16,
  2326  	{ir.OADD, types.TUINT16}:  ssa.OpAdd16,
  2327  	{ir.OADD, types.TINT32}:   ssa.OpAdd32,
  2328  	{ir.OADD, types.TUINT32}:  ssa.OpAdd32,
  2329  	{ir.OADD, types.TINT64}:   ssa.OpAdd64,
  2330  	{ir.OADD, types.TUINT64}:  ssa.OpAdd64,
  2331  	{ir.OADD, types.TFLOAT32}: ssa.OpAdd32F,
  2332  	{ir.OADD, types.TFLOAT64}: ssa.OpAdd64F,
  2333  
  2334  	{ir.OSUB, types.TINT8}:    ssa.OpSub8,
  2335  	{ir.OSUB, types.TUINT8}:   ssa.OpSub8,
  2336  	{ir.OSUB, types.TINT16}:   ssa.OpSub16,
  2337  	{ir.OSUB, types.TUINT16}:  ssa.OpSub16,
  2338  	{ir.OSUB, types.TINT32}:   ssa.OpSub32,
  2339  	{ir.OSUB, types.TUINT32}:  ssa.OpSub32,
  2340  	{ir.OSUB, types.TINT64}:   ssa.OpSub64,
  2341  	{ir.OSUB, types.TUINT64}:  ssa.OpSub64,
  2342  	{ir.OSUB, types.TFLOAT32}: ssa.OpSub32F,
  2343  	{ir.OSUB, types.TFLOAT64}: ssa.OpSub64F,
  2344  
  2345  	{ir.ONOT, types.TBOOL}: ssa.OpNot,
  2346  
  2347  	{ir.ONEG, types.TINT8}:    ssa.OpNeg8,
  2348  	{ir.ONEG, types.TUINT8}:   ssa.OpNeg8,
  2349  	{ir.ONEG, types.TINT16}:   ssa.OpNeg16,
  2350  	{ir.ONEG, types.TUINT16}:  ssa.OpNeg16,
  2351  	{ir.ONEG, types.TINT32}:   ssa.OpNeg32,
  2352  	{ir.ONEG, types.TUINT32}:  ssa.OpNeg32,
  2353  	{ir.ONEG, types.TINT64}:   ssa.OpNeg64,
  2354  	{ir.ONEG, types.TUINT64}:  ssa.OpNeg64,
  2355  	{ir.ONEG, types.TFLOAT32}: ssa.OpNeg32F,
  2356  	{ir.ONEG, types.TFLOAT64}: ssa.OpNeg64F,
  2357  
  2358  	{ir.OBITNOT, types.TINT8}:   ssa.OpCom8,
  2359  	{ir.OBITNOT, types.TUINT8}:  ssa.OpCom8,
  2360  	{ir.OBITNOT, types.TINT16}:  ssa.OpCom16,
  2361  	{ir.OBITNOT, types.TUINT16}: ssa.OpCom16,
  2362  	{ir.OBITNOT, types.TINT32}:  ssa.OpCom32,
  2363  	{ir.OBITNOT, types.TUINT32}: ssa.OpCom32,
  2364  	{ir.OBITNOT, types.TINT64}:  ssa.OpCom64,
  2365  	{ir.OBITNOT, types.TUINT64}: ssa.OpCom64,
  2366  
  2367  	{ir.OIMAG, types.TCOMPLEX64}:  ssa.OpComplexImag,
  2368  	{ir.OIMAG, types.TCOMPLEX128}: ssa.OpComplexImag,
  2369  	{ir.OREAL, types.TCOMPLEX64}:  ssa.OpComplexReal,
  2370  	{ir.OREAL, types.TCOMPLEX128}: ssa.OpComplexReal,
  2371  
  2372  	{ir.OMUL, types.TINT8}:    ssa.OpMul8,
  2373  	{ir.OMUL, types.TUINT8}:   ssa.OpMul8,
  2374  	{ir.OMUL, types.TINT16}:   ssa.OpMul16,
  2375  	{ir.OMUL, types.TUINT16}:  ssa.OpMul16,
  2376  	{ir.OMUL, types.TINT32}:   ssa.OpMul32,
  2377  	{ir.OMUL, types.TUINT32}:  ssa.OpMul32,
  2378  	{ir.OMUL, types.TINT64}:   ssa.OpMul64,
  2379  	{ir.OMUL, types.TUINT64}:  ssa.OpMul64,
  2380  	{ir.OMUL, types.TFLOAT32}: ssa.OpMul32F,
  2381  	{ir.OMUL, types.TFLOAT64}: ssa.OpMul64F,
  2382  
  2383  	{ir.ODIV, types.TFLOAT32}: ssa.OpDiv32F,
  2384  	{ir.ODIV, types.TFLOAT64}: ssa.OpDiv64F,
  2385  
  2386  	{ir.ODIV, types.TINT8}:   ssa.OpDiv8,
  2387  	{ir.ODIV, types.TUINT8}:  ssa.OpDiv8u,
  2388  	{ir.ODIV, types.TINT16}:  ssa.OpDiv16,
  2389  	{ir.ODIV, types.TUINT16}: ssa.OpDiv16u,
  2390  	{ir.ODIV, types.TINT32}:  ssa.OpDiv32,
  2391  	{ir.ODIV, types.TUINT32}: ssa.OpDiv32u,
  2392  	{ir.ODIV, types.TINT64}:  ssa.OpDiv64,
  2393  	{ir.ODIV, types.TUINT64}: ssa.OpDiv64u,
  2394  
  2395  	{ir.OMOD, types.TINT8}:   ssa.OpMod8,
  2396  	{ir.OMOD, types.TUINT8}:  ssa.OpMod8u,
  2397  	{ir.OMOD, types.TINT16}:  ssa.OpMod16,
  2398  	{ir.OMOD, types.TUINT16}: ssa.OpMod16u,
  2399  	{ir.OMOD, types.TINT32}:  ssa.OpMod32,
  2400  	{ir.OMOD, types.TUINT32}: ssa.OpMod32u,
  2401  	{ir.OMOD, types.TINT64}:  ssa.OpMod64,
  2402  	{ir.OMOD, types.TUINT64}: ssa.OpMod64u,
  2403  
  2404  	{ir.OAND, types.TINT8}:   ssa.OpAnd8,
  2405  	{ir.OAND, types.TUINT8}:  ssa.OpAnd8,
  2406  	{ir.OAND, types.TINT16}:  ssa.OpAnd16,
  2407  	{ir.OAND, types.TUINT16}: ssa.OpAnd16,
  2408  	{ir.OAND, types.TINT32}:  ssa.OpAnd32,
  2409  	{ir.OAND, types.TUINT32}: ssa.OpAnd32,
  2410  	{ir.OAND, types.TINT64}:  ssa.OpAnd64,
  2411  	{ir.OAND, types.TUINT64}: ssa.OpAnd64,
  2412  
  2413  	{ir.OOR, types.TINT8}:   ssa.OpOr8,
  2414  	{ir.OOR, types.TUINT8}:  ssa.OpOr8,
  2415  	{ir.OOR, types.TINT16}:  ssa.OpOr16,
  2416  	{ir.OOR, types.TUINT16}: ssa.OpOr16,
  2417  	{ir.OOR, types.TINT32}:  ssa.OpOr32,
  2418  	{ir.OOR, types.TUINT32}: ssa.OpOr32,
  2419  	{ir.OOR, types.TINT64}:  ssa.OpOr64,
  2420  	{ir.OOR, types.TUINT64}: ssa.OpOr64,
  2421  
  2422  	{ir.OXOR, types.TINT8}:   ssa.OpXor8,
  2423  	{ir.OXOR, types.TUINT8}:  ssa.OpXor8,
  2424  	{ir.OXOR, types.TINT16}:  ssa.OpXor16,
  2425  	{ir.OXOR, types.TUINT16}: ssa.OpXor16,
  2426  	{ir.OXOR, types.TINT32}:  ssa.OpXor32,
  2427  	{ir.OXOR, types.TUINT32}: ssa.OpXor32,
  2428  	{ir.OXOR, types.TINT64}:  ssa.OpXor64,
  2429  	{ir.OXOR, types.TUINT64}: ssa.OpXor64,
  2430  
  2431  	{ir.OEQ, types.TBOOL}:      ssa.OpEqB,
  2432  	{ir.OEQ, types.TINT8}:      ssa.OpEq8,
  2433  	{ir.OEQ, types.TUINT8}:     ssa.OpEq8,
  2434  	{ir.OEQ, types.TINT16}:     ssa.OpEq16,
  2435  	{ir.OEQ, types.TUINT16}:    ssa.OpEq16,
  2436  	{ir.OEQ, types.TINT32}:     ssa.OpEq32,
  2437  	{ir.OEQ, types.TUINT32}:    ssa.OpEq32,
  2438  	{ir.OEQ, types.TINT64}:     ssa.OpEq64,
  2439  	{ir.OEQ, types.TUINT64}:    ssa.OpEq64,
  2440  	{ir.OEQ, types.TINTER}:     ssa.OpEqInter,
  2441  	{ir.OEQ, types.TSLICE}:     ssa.OpEqSlice,
  2442  	{ir.OEQ, types.TFUNC}:      ssa.OpEqPtr,
  2443  	{ir.OEQ, types.TMAP}:       ssa.OpEqPtr,
  2444  	{ir.OEQ, types.TCHAN}:      ssa.OpEqPtr,
  2445  	{ir.OEQ, types.TPTR}:       ssa.OpEqPtr,
  2446  	{ir.OEQ, types.TUINTPTR}:   ssa.OpEqPtr,
  2447  	{ir.OEQ, types.TUNSAFEPTR}: ssa.OpEqPtr,
  2448  	{ir.OEQ, types.TFLOAT64}:   ssa.OpEq64F,
  2449  	{ir.OEQ, types.TFLOAT32}:   ssa.OpEq32F,
  2450  
  2451  	{ir.ONE, types.TBOOL}:      ssa.OpNeqB,
  2452  	{ir.ONE, types.TINT8}:      ssa.OpNeq8,
  2453  	{ir.ONE, types.TUINT8}:     ssa.OpNeq8,
  2454  	{ir.ONE, types.TINT16}:     ssa.OpNeq16,
  2455  	{ir.ONE, types.TUINT16}:    ssa.OpNeq16,
  2456  	{ir.ONE, types.TINT32}:     ssa.OpNeq32,
  2457  	{ir.ONE, types.TUINT32}:    ssa.OpNeq32,
  2458  	{ir.ONE, types.TINT64}:     ssa.OpNeq64,
  2459  	{ir.ONE, types.TUINT64}:    ssa.OpNeq64,
  2460  	{ir.ONE, types.TINTER}:     ssa.OpNeqInter,
  2461  	{ir.ONE, types.TSLICE}:     ssa.OpNeqSlice,
  2462  	{ir.ONE, types.TFUNC}:      ssa.OpNeqPtr,
  2463  	{ir.ONE, types.TMAP}:       ssa.OpNeqPtr,
  2464  	{ir.ONE, types.TCHAN}:      ssa.OpNeqPtr,
  2465  	{ir.ONE, types.TPTR}:       ssa.OpNeqPtr,
  2466  	{ir.ONE, types.TUINTPTR}:   ssa.OpNeqPtr,
  2467  	{ir.ONE, types.TUNSAFEPTR}: ssa.OpNeqPtr,
  2468  	{ir.ONE, types.TFLOAT64}:   ssa.OpNeq64F,
  2469  	{ir.ONE, types.TFLOAT32}:   ssa.OpNeq32F,
  2470  
  2471  	{ir.OLT, types.TINT8}:    ssa.OpLess8,
  2472  	{ir.OLT, types.TUINT8}:   ssa.OpLess8U,
  2473  	{ir.OLT, types.TINT16}:   ssa.OpLess16,
  2474  	{ir.OLT, types.TUINT16}:  ssa.OpLess16U,
  2475  	{ir.OLT, types.TINT32}:   ssa.OpLess32,
  2476  	{ir.OLT, types.TUINT32}:  ssa.OpLess32U,
  2477  	{ir.OLT, types.TINT64}:   ssa.OpLess64,
  2478  	{ir.OLT, types.TUINT64}:  ssa.OpLess64U,
  2479  	{ir.OLT, types.TFLOAT64}: ssa.OpLess64F,
  2480  	{ir.OLT, types.TFLOAT32}: ssa.OpLess32F,
  2481  
  2482  	{ir.OLE, types.TINT8}:    ssa.OpLeq8,
  2483  	{ir.OLE, types.TUINT8}:   ssa.OpLeq8U,
  2484  	{ir.OLE, types.TINT16}:   ssa.OpLeq16,
  2485  	{ir.OLE, types.TUINT16}:  ssa.OpLeq16U,
  2486  	{ir.OLE, types.TINT32}:   ssa.OpLeq32,
  2487  	{ir.OLE, types.TUINT32}:  ssa.OpLeq32U,
  2488  	{ir.OLE, types.TINT64}:   ssa.OpLeq64,
  2489  	{ir.OLE, types.TUINT64}:  ssa.OpLeq64U,
  2490  	{ir.OLE, types.TFLOAT64}: ssa.OpLeq64F,
  2491  	{ir.OLE, types.TFLOAT32}: ssa.OpLeq32F,
  2492  }
  2493  
  2494  func (s *state) concreteEtype(t *types.Type) types.Kind {
  2495  	e := t.Kind()
  2496  	switch e {
  2497  	default:
  2498  		return e
  2499  	case types.TINT:
  2500  		if s.config.PtrSize == 8 {
  2501  			return types.TINT64
  2502  		}
  2503  		return types.TINT32
  2504  	case types.TUINT:
  2505  		if s.config.PtrSize == 8 {
  2506  			return types.TUINT64
  2507  		}
  2508  		return types.TUINT32
  2509  	case types.TUINTPTR:
  2510  		if s.config.PtrSize == 8 {
  2511  			return types.TUINT64
  2512  		}
  2513  		return types.TUINT32
  2514  	}
  2515  }
  2516  
  2517  func (s *state) ssaOp(op ir.Op, t *types.Type) ssa.Op {
  2518  	etype := s.concreteEtype(t)
  2519  	x, ok := opToSSA[opAndType{op, etype}]
  2520  	if !ok {
  2521  		s.Fatalf("unhandled binary op %v %s", op, etype)
  2522  	}
  2523  	return x
  2524  }
  2525  
  2526  type opAndTwoTypes struct {
  2527  	op     ir.Op
  2528  	etype1 types.Kind
  2529  	etype2 types.Kind
  2530  }
  2531  
  2532  type twoTypes struct {
  2533  	etype1 types.Kind
  2534  	etype2 types.Kind
  2535  }
  2536  
  2537  type twoOpsAndType struct {
  2538  	op1              ssa.Op
  2539  	op2              ssa.Op
  2540  	intermediateType types.Kind
  2541  }
  2542  
  2543  var fpConvOpToSSA = map[twoTypes]twoOpsAndType{
  2544  
  2545  	{types.TINT8, types.TFLOAT32}:  {ssa.OpSignExt8to32, ssa.OpCvt32to32F, types.TINT32},
  2546  	{types.TINT16, types.TFLOAT32}: {ssa.OpSignExt16to32, ssa.OpCvt32to32F, types.TINT32},
  2547  	{types.TINT32, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt32to32F, types.TINT32},
  2548  	{types.TINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt64to32F, types.TINT64},
  2549  
  2550  	{types.TINT8, types.TFLOAT64}:  {ssa.OpSignExt8to32, ssa.OpCvt32to64F, types.TINT32},
  2551  	{types.TINT16, types.TFLOAT64}: {ssa.OpSignExt16to32, ssa.OpCvt32to64F, types.TINT32},
  2552  	{types.TINT32, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt32to64F, types.TINT32},
  2553  	{types.TINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt64to64F, types.TINT64},
  2554  
  2555  	{types.TFLOAT32, types.TINT8}:  {ssa.OpCvt32Fto32, ssa.OpTrunc32to8, types.TINT32},
  2556  	{types.TFLOAT32, types.TINT16}: {ssa.OpCvt32Fto32, ssa.OpTrunc32to16, types.TINT32},
  2557  	{types.TFLOAT32, types.TINT32}: {ssa.OpCvt32Fto32, ssa.OpCopy, types.TINT32},
  2558  	{types.TFLOAT32, types.TINT64}: {ssa.OpCvt32Fto64, ssa.OpCopy, types.TINT64},
  2559  
  2560  	{types.TFLOAT64, types.TINT8}:  {ssa.OpCvt64Fto32, ssa.OpTrunc32to8, types.TINT32},
  2561  	{types.TFLOAT64, types.TINT16}: {ssa.OpCvt64Fto32, ssa.OpTrunc32to16, types.TINT32},
  2562  	{types.TFLOAT64, types.TINT32}: {ssa.OpCvt64Fto32, ssa.OpCopy, types.TINT32},
  2563  	{types.TFLOAT64, types.TINT64}: {ssa.OpCvt64Fto64, ssa.OpCopy, types.TINT64},
  2564  	// unsigned
  2565  	{types.TUINT8, types.TFLOAT32}:  {ssa.OpZeroExt8to32, ssa.OpCvt32to32F, types.TINT32},
  2566  	{types.TUINT16, types.TFLOAT32}: {ssa.OpZeroExt16to32, ssa.OpCvt32to32F, types.TINT32},
  2567  	{types.TUINT32, types.TFLOAT32}: {ssa.OpZeroExt32to64, ssa.OpCvt64to32F, types.TINT64}, // go wide to dodge unsigned
  2568  	{types.TUINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpInvalid, types.TUINT64},            // Cvt64Uto32F, branchy code expansion instead
  2569  
  2570  	{types.TUINT8, types.TFLOAT64}:  {ssa.OpZeroExt8to32, ssa.OpCvt32to64F, types.TINT32},
  2571  	{types.TUINT16, types.TFLOAT64}: {ssa.OpZeroExt16to32, ssa.OpCvt32to64F, types.TINT32},
  2572  	{types.TUINT32, types.TFLOAT64}: {ssa.OpZeroExt32to64, ssa.OpCvt64to64F, types.TINT64}, // go wide to dodge unsigned
  2573  	{types.TUINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpInvalid, types.TUINT64},            // Cvt64Uto64F, branchy code expansion instead
  2574  
  2575  	{types.TFLOAT32, types.TUINT8}:  {ssa.OpCvt32Fto32, ssa.OpTrunc32to8, types.TINT32},
  2576  	{types.TFLOAT32, types.TUINT16}: {ssa.OpCvt32Fto32, ssa.OpTrunc32to16, types.TINT32},
  2577  	{types.TFLOAT32, types.TUINT32}: {ssa.OpCvt32Fto64, ssa.OpTrunc64to32, types.TINT64}, // go wide to dodge unsigned
  2578  	{types.TFLOAT32, types.TUINT64}: {ssa.OpInvalid, ssa.OpCopy, types.TUINT64},          // Cvt32Fto64U, branchy code expansion instead
  2579  
  2580  	{types.TFLOAT64, types.TUINT8}:  {ssa.OpCvt64Fto32, ssa.OpTrunc32to8, types.TINT32},
  2581  	{types.TFLOAT64, types.TUINT16}: {ssa.OpCvt64Fto32, ssa.OpTrunc32to16, types.TINT32},
  2582  	{types.TFLOAT64, types.TUINT32}: {ssa.OpCvt64Fto64, ssa.OpTrunc64to32, types.TINT64}, // go wide to dodge unsigned
  2583  	{types.TFLOAT64, types.TUINT64}: {ssa.OpInvalid, ssa.OpCopy, types.TUINT64},          // Cvt64Fto64U, branchy code expansion instead
  2584  
  2585  	// float
  2586  	{types.TFLOAT64, types.TFLOAT32}: {ssa.OpCvt64Fto32F, ssa.OpCopy, types.TFLOAT32},
  2587  	{types.TFLOAT64, types.TFLOAT64}: {ssa.OpRound64F, ssa.OpCopy, types.TFLOAT64},
  2588  	{types.TFLOAT32, types.TFLOAT32}: {ssa.OpRound32F, ssa.OpCopy, types.TFLOAT32},
  2589  	{types.TFLOAT32, types.TFLOAT64}: {ssa.OpCvt32Fto64F, ssa.OpCopy, types.TFLOAT64},
  2590  }
  2591  
  2592  // this map is used only for 32-bit arch, and only includes the difference
  2593  // on 32-bit arch, don't use int64<->float conversion for uint32
  2594  var fpConvOpToSSA32 = map[twoTypes]twoOpsAndType{
  2595  	{types.TUINT32, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt32Uto32F, types.TUINT32},
  2596  	{types.TUINT32, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt32Uto64F, types.TUINT32},
  2597  	{types.TFLOAT32, types.TUINT32}: {ssa.OpCvt32Fto32U, ssa.OpCopy, types.TUINT32},
  2598  	{types.TFLOAT64, types.TUINT32}: {ssa.OpCvt64Fto32U, ssa.OpCopy, types.TUINT32},
  2599  }
  2600  
  2601  // uint64<->float conversions, only on machines that have instructions for that
  2602  var uint64fpConvOpToSSA = map[twoTypes]twoOpsAndType{
  2603  	{types.TUINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt64Uto32F, types.TUINT64},
  2604  	{types.TUINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt64Uto64F, types.TUINT64},
  2605  	{types.TFLOAT32, types.TUINT64}: {ssa.OpCvt32Fto64U, ssa.OpCopy, types.TUINT64},
  2606  	{types.TFLOAT64, types.TUINT64}: {ssa.OpCvt64Fto64U, ssa.OpCopy, types.TUINT64},
  2607  }
  2608  
  2609  var shiftOpToSSA = map[opAndTwoTypes]ssa.Op{
  2610  	{ir.OLSH, types.TINT8, types.TUINT8}:   ssa.OpLsh8x8,
  2611  	{ir.OLSH, types.TUINT8, types.TUINT8}:  ssa.OpLsh8x8,
  2612  	{ir.OLSH, types.TINT8, types.TUINT16}:  ssa.OpLsh8x16,
  2613  	{ir.OLSH, types.TUINT8, types.TUINT16}: ssa.OpLsh8x16,
  2614  	{ir.OLSH, types.TINT8, types.TUINT32}:  ssa.OpLsh8x32,
  2615  	{ir.OLSH, types.TUINT8, types.TUINT32}: ssa.OpLsh8x32,
  2616  	{ir.OLSH, types.TINT8, types.TUINT64}:  ssa.OpLsh8x64,
  2617  	{ir.OLSH, types.TUINT8, types.TUINT64}: ssa.OpLsh8x64,
  2618  
  2619  	{ir.OLSH, types.TINT16, types.TUINT8}:   ssa.OpLsh16x8,
  2620  	{ir.OLSH, types.TUINT16, types.TUINT8}:  ssa.OpLsh16x8,
  2621  	{ir.OLSH, types.TINT16, types.TUINT16}:  ssa.OpLsh16x16,
  2622  	{ir.OLSH, types.TUINT16, types.TUINT16}: ssa.OpLsh16x16,
  2623  	{ir.OLSH, types.TINT16, types.TUINT32}:  ssa.OpLsh16x32,
  2624  	{ir.OLSH, types.TUINT16, types.TUINT32}: ssa.OpLsh16x32,
  2625  	{ir.OLSH, types.TINT16, types.TUINT64}:  ssa.OpLsh16x64,
  2626  	{ir.OLSH, types.TUINT16, types.TUINT64}: ssa.OpLsh16x64,
  2627  
  2628  	{ir.OLSH, types.TINT32, types.TUINT8}:   ssa.OpLsh32x8,
  2629  	{ir.OLSH, types.TUINT32, types.TUINT8}:  ssa.OpLsh32x8,
  2630  	{ir.OLSH, types.TINT32, types.TUINT16}:  ssa.OpLsh32x16,
  2631  	{ir.OLSH, types.TUINT32, types.TUINT16}: ssa.OpLsh32x16,
  2632  	{ir.OLSH, types.TINT32, types.TUINT32}:  ssa.OpLsh32x32,
  2633  	{ir.OLSH, types.TUINT32, types.TUINT32}: ssa.OpLsh32x32,
  2634  	{ir.OLSH, types.TINT32, types.TUINT64}:  ssa.OpLsh32x64,
  2635  	{ir.OLSH, types.TUINT32, types.TUINT64}: ssa.OpLsh32x64,
  2636  
  2637  	{ir.OLSH, types.TINT64, types.TUINT8}:   ssa.OpLsh64x8,
  2638  	{ir.OLSH, types.TUINT64, types.TUINT8}:  ssa.OpLsh64x8,
  2639  	{ir.OLSH, types.TINT64, types.TUINT16}:  ssa.OpLsh64x16,
  2640  	{ir.OLSH, types.TUINT64, types.TUINT16}: ssa.OpLsh64x16,
  2641  	{ir.OLSH, types.TINT64, types.TUINT32}:  ssa.OpLsh64x32,
  2642  	{ir.OLSH, types.TUINT64, types.TUINT32}: ssa.OpLsh64x32,
  2643  	{ir.OLSH, types.TINT64, types.TUINT64}:  ssa.OpLsh64x64,
  2644  	{ir.OLSH, types.TUINT64, types.TUINT64}: ssa.OpLsh64x64,
  2645  
  2646  	{ir.ORSH, types.TINT8, types.TUINT8}:   ssa.OpRsh8x8,
  2647  	{ir.ORSH, types.TUINT8, types.TUINT8}:  ssa.OpRsh8Ux8,
  2648  	{ir.ORSH, types.TINT8, types.TUINT16}:  ssa.OpRsh8x16,
  2649  	{ir.ORSH, types.TUINT8, types.TUINT16}: ssa.OpRsh8Ux16,
  2650  	{ir.ORSH, types.TINT8, types.TUINT32}:  ssa.OpRsh8x32,
  2651  	{ir.ORSH, types.TUINT8, types.TUINT32}: ssa.OpRsh8Ux32,
  2652  	{ir.ORSH, types.TINT8, types.TUINT64}:  ssa.OpRsh8x64,
  2653  	{ir.ORSH, types.TUINT8, types.TUINT64}: ssa.OpRsh8Ux64,
  2654  
  2655  	{ir.ORSH, types.TINT16, types.TUINT8}:   ssa.OpRsh16x8,
  2656  	{ir.ORSH, types.TUINT16, types.TUINT8}:  ssa.OpRsh16Ux8,
  2657  	{ir.ORSH, types.TINT16, types.TUINT16}:  ssa.OpRsh16x16,
  2658  	{ir.ORSH, types.TUINT16, types.TUINT16}: ssa.OpRsh16Ux16,
  2659  	{ir.ORSH, types.TINT16, types.TUINT32}:  ssa.OpRsh16x32,
  2660  	{ir.ORSH, types.TUINT16, types.TUINT32}: ssa.OpRsh16Ux32,
  2661  	{ir.ORSH, types.TINT16, types.TUINT64}:  ssa.OpRsh16x64,
  2662  	{ir.ORSH, types.TUINT16, types.TUINT64}: ssa.OpRsh16Ux64,
  2663  
  2664  	{ir.ORSH, types.TINT32, types.TUINT8}:   ssa.OpRsh32x8,
  2665  	{ir.ORSH, types.TUINT32, types.TUINT8}:  ssa.OpRsh32Ux8,
  2666  	{ir.ORSH, types.TINT32, types.TUINT16}:  ssa.OpRsh32x16,
  2667  	{ir.ORSH, types.TUINT32, types.TUINT16}: ssa.OpRsh32Ux16,
  2668  	{ir.ORSH, types.TINT32, types.TUINT32}:  ssa.OpRsh32x32,
  2669  	{ir.ORSH, types.TUINT32, types.TUINT32}: ssa.OpRsh32Ux32,
  2670  	{ir.ORSH, types.TINT32, types.TUINT64}:  ssa.OpRsh32x64,
  2671  	{ir.ORSH, types.TUINT32, types.TUINT64}: ssa.OpRsh32Ux64,
  2672  
  2673  	{ir.ORSH, types.TINT64, types.TUINT8}:   ssa.OpRsh64x8,
  2674  	{ir.ORSH, types.TUINT64, types.TUINT8}:  ssa.OpRsh64Ux8,
  2675  	{ir.ORSH, types.TINT64, types.TUINT16}:  ssa.OpRsh64x16,
  2676  	{ir.ORSH, types.TUINT64, types.TUINT16}: ssa.OpRsh64Ux16,
  2677  	{ir.ORSH, types.TINT64, types.TUINT32}:  ssa.OpRsh64x32,
  2678  	{ir.ORSH, types.TUINT64, types.TUINT32}: ssa.OpRsh64Ux32,
  2679  	{ir.ORSH, types.TINT64, types.TUINT64}:  ssa.OpRsh64x64,
  2680  	{ir.ORSH, types.TUINT64, types.TUINT64}: ssa.OpRsh64Ux64,
  2681  }
  2682  
  2683  func (s *state) ssaShiftOp(op ir.Op, t *types.Type, u *types.Type) ssa.Op {
  2684  	etype1 := s.concreteEtype(t)
  2685  	etype2 := s.concreteEtype(u)
  2686  	x, ok := shiftOpToSSA[opAndTwoTypes{op, etype1, etype2}]
  2687  	if !ok {
  2688  		s.Fatalf("unhandled shift op %v etype=%s/%s", op, etype1, etype2)
  2689  	}
  2690  	return x
  2691  }
  2692  
  2693  func (s *state) uintptrConstant(v uint64) *ssa.Value {
  2694  	if s.config.PtrSize == 4 {
  2695  		return s.newValue0I(ssa.OpConst32, types.Types[types.TUINTPTR], int64(v))
  2696  	}
  2697  	return s.newValue0I(ssa.OpConst64, types.Types[types.TUINTPTR], int64(v))
  2698  }
  2699  
  2700  func (s *state) conv(n ir.Node, v *ssa.Value, ft, tt *types.Type) *ssa.Value {
  2701  	if ft.IsBoolean() && tt.IsKind(types.TUINT8) {
  2702  		// Bool -> uint8 is generated internally when indexing into runtime.staticbyte.
  2703  		return s.newValue1(ssa.OpCvtBoolToUint8, tt, v)
  2704  	}
  2705  	if ft.IsInteger() && tt.IsInteger() {
  2706  		var op ssa.Op
  2707  		if tt.Size() == ft.Size() {
  2708  			op = ssa.OpCopy
  2709  		} else if tt.Size() < ft.Size() {
  2710  			// truncation
  2711  			switch 10*ft.Size() + tt.Size() {
  2712  			case 21:
  2713  				op = ssa.OpTrunc16to8
  2714  			case 41:
  2715  				op = ssa.OpTrunc32to8
  2716  			case 42:
  2717  				op = ssa.OpTrunc32to16
  2718  			case 81:
  2719  				op = ssa.OpTrunc64to8
  2720  			case 82:
  2721  				op = ssa.OpTrunc64to16
  2722  			case 84:
  2723  				op = ssa.OpTrunc64to32
  2724  			default:
  2725  				s.Fatalf("weird integer truncation %v -> %v", ft, tt)
  2726  			}
  2727  		} else if ft.IsSigned() {
  2728  			// sign extension
  2729  			switch 10*ft.Size() + tt.Size() {
  2730  			case 12:
  2731  				op = ssa.OpSignExt8to16
  2732  			case 14:
  2733  				op = ssa.OpSignExt8to32
  2734  			case 18:
  2735  				op = ssa.OpSignExt8to64
  2736  			case 24:
  2737  				op = ssa.OpSignExt16to32
  2738  			case 28:
  2739  				op = ssa.OpSignExt16to64
  2740  			case 48:
  2741  				op = ssa.OpSignExt32to64
  2742  			default:
  2743  				s.Fatalf("bad integer sign extension %v -> %v", ft, tt)
  2744  			}
  2745  		} else {
  2746  			// zero extension
  2747  			switch 10*ft.Size() + tt.Size() {
  2748  			case 12:
  2749  				op = ssa.OpZeroExt8to16
  2750  			case 14:
  2751  				op = ssa.OpZeroExt8to32
  2752  			case 18:
  2753  				op = ssa.OpZeroExt8to64
  2754  			case 24:
  2755  				op = ssa.OpZeroExt16to32
  2756  			case 28:
  2757  				op = ssa.OpZeroExt16to64
  2758  			case 48:
  2759  				op = ssa.OpZeroExt32to64
  2760  			default:
  2761  				s.Fatalf("weird integer sign extension %v -> %v", ft, tt)
  2762  			}
  2763  		}
  2764  		return s.newValue1(op, tt, v)
  2765  	}
  2766  
  2767  	if ft.IsComplex() && tt.IsComplex() {
  2768  		var op ssa.Op
  2769  		if ft.Size() == tt.Size() {
  2770  			switch ft.Size() {
  2771  			case 8:
  2772  				op = ssa.OpRound32F
  2773  			case 16:
  2774  				op = ssa.OpRound64F
  2775  			default:
  2776  				s.Fatalf("weird complex conversion %v -> %v", ft, tt)
  2777  			}
  2778  		} else if ft.Size() == 8 && tt.Size() == 16 {
  2779  			op = ssa.OpCvt32Fto64F
  2780  		} else if ft.Size() == 16 && tt.Size() == 8 {
  2781  			op = ssa.OpCvt64Fto32F
  2782  		} else {
  2783  			s.Fatalf("weird complex conversion %v -> %v", ft, tt)
  2784  		}
  2785  		ftp := types.FloatForComplex(ft)
  2786  		ttp := types.FloatForComplex(tt)
  2787  		return s.newValue2(ssa.OpComplexMake, tt,
  2788  			s.newValueOrSfCall1(op, ttp, s.newValue1(ssa.OpComplexReal, ftp, v)),
  2789  			s.newValueOrSfCall1(op, ttp, s.newValue1(ssa.OpComplexImag, ftp, v)))
  2790  	}
  2791  
  2792  	if tt.IsComplex() { // and ft is not complex
  2793  		// Needed for generics support - can't happen in normal Go code.
  2794  		et := types.FloatForComplex(tt)
  2795  		v = s.conv(n, v, ft, et)
  2796  		return s.newValue2(ssa.OpComplexMake, tt, v, s.zeroVal(et))
  2797  	}
  2798  
  2799  	if ft.IsFloat() || tt.IsFloat() {
  2800  		conv, ok := fpConvOpToSSA[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]
  2801  		if s.config.RegSize == 4 && Arch.LinkArch.Family != sys.MIPS && !s.softFloat {
  2802  			if conv1, ok1 := fpConvOpToSSA32[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
  2803  				conv = conv1
  2804  			}
  2805  		}
  2806  		if Arch.LinkArch.Family == sys.ARM64 || Arch.LinkArch.Family == sys.Wasm || Arch.LinkArch.Family == sys.S390X || s.softFloat {
  2807  			if conv1, ok1 := uint64fpConvOpToSSA[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
  2808  				conv = conv1
  2809  			}
  2810  		}
  2811  
  2812  		if Arch.LinkArch.Family == sys.MIPS && !s.softFloat {
  2813  			if ft.Size() == 4 && ft.IsInteger() && !ft.IsSigned() {
  2814  				// tt is float32 or float64, and ft is also unsigned
  2815  				if tt.Size() == 4 {
  2816  					return s.uint32Tofloat32(n, v, ft, tt)
  2817  				}
  2818  				if tt.Size() == 8 {
  2819  					return s.uint32Tofloat64(n, v, ft, tt)
  2820  				}
  2821  			} else if tt.Size() == 4 && tt.IsInteger() && !tt.IsSigned() {
  2822  				// ft is float32 or float64, and tt is unsigned integer
  2823  				if ft.Size() == 4 {
  2824  					return s.float32ToUint32(n, v, ft, tt)
  2825  				}
  2826  				if ft.Size() == 8 {
  2827  					return s.float64ToUint32(n, v, ft, tt)
  2828  				}
  2829  			}
  2830  		}
  2831  
  2832  		if !ok {
  2833  			s.Fatalf("weird float conversion %v -> %v", ft, tt)
  2834  		}
  2835  		op1, op2, it := conv.op1, conv.op2, conv.intermediateType
  2836  
  2837  		if op1 != ssa.OpInvalid && op2 != ssa.OpInvalid {
  2838  			// normal case, not tripping over unsigned 64
  2839  			if op1 == ssa.OpCopy {
  2840  				if op2 == ssa.OpCopy {
  2841  					return v
  2842  				}
  2843  				return s.newValueOrSfCall1(op2, tt, v)
  2844  			}
  2845  			if op2 == ssa.OpCopy {
  2846  				return s.newValueOrSfCall1(op1, tt, v)
  2847  			}
  2848  			return s.newValueOrSfCall1(op2, tt, s.newValueOrSfCall1(op1, types.Types[it], v))
  2849  		}
  2850  		// Tricky 64-bit unsigned cases.
  2851  		if ft.IsInteger() {
  2852  			// tt is float32 or float64, and ft is also unsigned
  2853  			if tt.Size() == 4 {
  2854  				return s.uint64Tofloat32(n, v, ft, tt)
  2855  			}
  2856  			if tt.Size() == 8 {
  2857  				return s.uint64Tofloat64(n, v, ft, tt)
  2858  			}
  2859  			s.Fatalf("weird unsigned integer to float conversion %v -> %v", ft, tt)
  2860  		}
  2861  		// ft is float32 or float64, and tt is unsigned integer
  2862  		if ft.Size() == 4 {
  2863  			return s.float32ToUint64(n, v, ft, tt)
  2864  		}
  2865  		if ft.Size() == 8 {
  2866  			return s.float64ToUint64(n, v, ft, tt)
  2867  		}
  2868  		s.Fatalf("weird float to unsigned integer conversion %v -> %v", ft, tt)
  2869  		return nil
  2870  	}
  2871  
  2872  	s.Fatalf("unhandled OCONV %s -> %s", ft.Kind(), tt.Kind())
  2873  	return nil
  2874  }
  2875  
  2876  // expr converts the expression n to ssa, adds it to s and returns the ssa result.
  2877  func (s *state) expr(n ir.Node) *ssa.Value {
  2878  	return s.exprCheckPtr(n, true)
  2879  }
  2880  
  2881  func (s *state) exprCheckPtr(n ir.Node, checkPtrOK bool) *ssa.Value {
  2882  	if ir.HasUniquePos(n) {
  2883  		// ONAMEs and named OLITERALs have the line number
  2884  		// of the decl, not the use. See issue 14742.
  2885  		s.pushLine(n.Pos())
  2886  		defer s.popLine()
  2887  	}
  2888  
  2889  	s.stmtList(n.Init())
  2890  	switch n.Op() {
  2891  	case ir.OBYTES2STRTMP:
  2892  		n := n.(*ir.ConvExpr)
  2893  		slice := s.expr(n.X)
  2894  		ptr := s.newValue1(ssa.OpSlicePtr, s.f.Config.Types.BytePtr, slice)
  2895  		len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], slice)
  2896  		return s.newValue2(ssa.OpStringMake, n.Type(), ptr, len)
  2897  	case ir.OSTR2BYTESTMP:
  2898  		n := n.(*ir.ConvExpr)
  2899  		str := s.expr(n.X)
  2900  		ptr := s.newValue1(ssa.OpStringPtr, s.f.Config.Types.BytePtr, str)
  2901  		if !n.NonNil() {
  2902  			// We need to ensure []byte("") evaluates to []byte{}, and not []byte(nil).
  2903  			//
  2904  			// TODO(mdempsky): Investigate using "len != 0" instead of "ptr != nil".
  2905  			cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], ptr, s.constNil(ptr.Type))
  2906  			zerobase := s.newValue1A(ssa.OpAddr, ptr.Type, ir.Syms.Zerobase, s.sb)
  2907  			ptr = s.ternary(cond, ptr, zerobase)
  2908  		}
  2909  		len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], str)
  2910  		return s.newValue3(ssa.OpSliceMake, n.Type(), ptr, len, len)
  2911  	case ir.OCFUNC:
  2912  		n := n.(*ir.UnaryExpr)
  2913  		aux := n.X.(*ir.Name).Linksym()
  2914  		// OCFUNC is used to build function values, which must
  2915  		// always reference ABIInternal entry points.
  2916  		if aux.ABI() != obj.ABIInternal {
  2917  			s.Fatalf("expected ABIInternal: %v", aux.ABI())
  2918  		}
  2919  		return s.entryNewValue1A(ssa.OpAddr, n.Type(), aux, s.sb)
  2920  	case ir.ONAME:
  2921  		n := n.(*ir.Name)
  2922  		if n.Class == ir.PFUNC {
  2923  			// "value" of a function is the address of the function's closure
  2924  			sym := staticdata.FuncLinksym(n)
  2925  			return s.entryNewValue1A(ssa.OpAddr, types.NewPtr(n.Type()), sym, s.sb)
  2926  		}
  2927  		if s.canSSA(n) {
  2928  			return s.variable(n, n.Type())
  2929  		}
  2930  		return s.load(n.Type(), s.addr(n))
  2931  	case ir.OLINKSYMOFFSET:
  2932  		n := n.(*ir.LinksymOffsetExpr)
  2933  		return s.load(n.Type(), s.addr(n))
  2934  	case ir.ONIL:
  2935  		n := n.(*ir.NilExpr)
  2936  		t := n.Type()
  2937  		switch {
  2938  		case t.IsSlice():
  2939  			return s.constSlice(t)
  2940  		case t.IsInterface():
  2941  			return s.constInterface(t)
  2942  		default:
  2943  			return s.constNil(t)
  2944  		}
  2945  	case ir.OLITERAL:
  2946  		switch u := n.Val(); u.Kind() {
  2947  		case constant.Int:
  2948  			i := ir.IntVal(n.Type(), u)
  2949  			switch n.Type().Size() {
  2950  			case 1:
  2951  				return s.constInt8(n.Type(), int8(i))
  2952  			case 2:
  2953  				return s.constInt16(n.Type(), int16(i))
  2954  			case 4:
  2955  				return s.constInt32(n.Type(), int32(i))
  2956  			case 8:
  2957  				return s.constInt64(n.Type(), i)
  2958  			default:
  2959  				s.Fatalf("bad integer size %d", n.Type().Size())
  2960  				return nil
  2961  			}
  2962  		case constant.String:
  2963  			i := constant.StringVal(u)
  2964  			if i == "" {
  2965  				return s.constEmptyString(n.Type())
  2966  			}
  2967  			return s.entryNewValue0A(ssa.OpConstString, n.Type(), ssa.StringToAux(i))
  2968  		case constant.Bool:
  2969  			return s.constBool(constant.BoolVal(u))
  2970  		case constant.Float:
  2971  			f, _ := constant.Float64Val(u)
  2972  			switch n.Type().Size() {
  2973  			case 4:
  2974  				return s.constFloat32(n.Type(), f)
  2975  			case 8:
  2976  				return s.constFloat64(n.Type(), f)
  2977  			default:
  2978  				s.Fatalf("bad float size %d", n.Type().Size())
  2979  				return nil
  2980  			}
  2981  		case constant.Complex:
  2982  			re, _ := constant.Float64Val(constant.Real(u))
  2983  			im, _ := constant.Float64Val(constant.Imag(u))
  2984  			switch n.Type().Size() {
  2985  			case 8:
  2986  				pt := types.Types[types.TFLOAT32]
  2987  				return s.newValue2(ssa.OpComplexMake, n.Type(),
  2988  					s.constFloat32(pt, re),
  2989  					s.constFloat32(pt, im))
  2990  			case 16:
  2991  				pt := types.Types[types.TFLOAT64]
  2992  				return s.newValue2(ssa.OpComplexMake, n.Type(),
  2993  					s.constFloat64(pt, re),
  2994  					s.constFloat64(pt, im))
  2995  			default:
  2996  				s.Fatalf("bad complex size %d", n.Type().Size())
  2997  				return nil
  2998  			}
  2999  		default:
  3000  			s.Fatalf("unhandled OLITERAL %v", u.Kind())
  3001  			return nil
  3002  		}
  3003  	case ir.OCONVNOP:
  3004  		n := n.(*ir.ConvExpr)
  3005  		to := n.Type()
  3006  		from := n.X.Type()
  3007  
  3008  		// Assume everything will work out, so set up our return value.
  3009  		// Anything interesting that happens from here is a fatal.
  3010  		x := s.expr(n.X)
  3011  		if to == from {
  3012  			return x
  3013  		}
  3014  
  3015  		// Special case for not confusing GC and liveness.
  3016  		// We don't want pointers accidentally classified
  3017  		// as not-pointers or vice-versa because of copy
  3018  		// elision.
  3019  		if to.IsPtrShaped() != from.IsPtrShaped() {
  3020  			return s.newValue2(ssa.OpConvert, to, x, s.mem())
  3021  		}
  3022  
  3023  		v := s.newValue1(ssa.OpCopy, to, x) // ensure that v has the right type
  3024  
  3025  		// CONVNOP closure
  3026  		if to.Kind() == types.TFUNC && from.IsPtrShaped() {
  3027  			return v
  3028  		}
  3029  
  3030  		// named <--> unnamed type or typed <--> untyped const
  3031  		if from.Kind() == to.Kind() {
  3032  			return v
  3033  		}
  3034  
  3035  		// unsafe.Pointer <--> *T
  3036  		if to.IsUnsafePtr() && from.IsPtrShaped() || from.IsUnsafePtr() && to.IsPtrShaped() {
  3037  			if s.checkPtrEnabled && checkPtrOK && to.IsPtr() && from.IsUnsafePtr() {
  3038  				s.checkPtrAlignment(n, v, nil)
  3039  			}
  3040  			return v
  3041  		}
  3042  
  3043  		// map <--> *internal/runtime/maps.Map
  3044  		mt := types.NewPtr(reflectdata.MapType())
  3045  		if to.Kind() == types.TMAP && from == mt {
  3046  			return v
  3047  		}
  3048  
  3049  		types.CalcSize(from)
  3050  		types.CalcSize(to)
  3051  		if from.Size() != to.Size() {
  3052  			s.Fatalf("CONVNOP width mismatch %v (%d) -> %v (%d)\n", from, from.Size(), to, to.Size())
  3053  			return nil
  3054  		}
  3055  		if etypesign(from.Kind()) != etypesign(to.Kind()) {
  3056  			s.Fatalf("CONVNOP sign mismatch %v (%s) -> %v (%s)\n", from, from.Kind(), to, to.Kind())
  3057  			return nil
  3058  		}
  3059  
  3060  		if base.Flag.Cfg.Instrumenting {
  3061  			// These appear to be fine, but they fail the
  3062  			// integer constraint below, so okay them here.
  3063  			// Sample non-integer conversion: map[string]string -> *uint8
  3064  			return v
  3065  		}
  3066  
  3067  		if etypesign(from.Kind()) == 0 {
  3068  			s.Fatalf("CONVNOP unrecognized non-integer %v -> %v\n", from, to)
  3069  			return nil
  3070  		}
  3071  
  3072  		// integer, same width, same sign
  3073  		return v
  3074  
  3075  	case ir.OCONV:
  3076  		n := n.(*ir.ConvExpr)
  3077  		x := s.expr(n.X)
  3078  		return s.conv(n, x, n.X.Type(), n.Type())
  3079  
  3080  	case ir.ODOTTYPE:
  3081  		n := n.(*ir.TypeAssertExpr)
  3082  		res, _ := s.dottype(n, false)
  3083  		return res
  3084  
  3085  	case ir.ODYNAMICDOTTYPE:
  3086  		n := n.(*ir.DynamicTypeAssertExpr)
  3087  		res, _ := s.dynamicDottype(n, false)
  3088  		return res
  3089  
  3090  	// binary ops
  3091  	case ir.OLT, ir.OEQ, ir.ONE, ir.OLE, ir.OGE, ir.OGT:
  3092  		n := n.(*ir.BinaryExpr)
  3093  		a := s.expr(n.X)
  3094  		b := s.expr(n.Y)
  3095  		if n.X.Type().IsComplex() {
  3096  			pt := types.FloatForComplex(n.X.Type())
  3097  			op := s.ssaOp(ir.OEQ, pt)
  3098  			r := s.newValueOrSfCall2(op, types.Types[types.TBOOL], s.newValue1(ssa.OpComplexReal, pt, a), s.newValue1(ssa.OpComplexReal, pt, b))
  3099  			i := s.newValueOrSfCall2(op, types.Types[types.TBOOL], s.newValue1(ssa.OpComplexImag, pt, a), s.newValue1(ssa.OpComplexImag, pt, b))
  3100  			c := s.newValue2(ssa.OpAndB, types.Types[types.TBOOL], r, i)
  3101  			switch n.Op() {
  3102  			case ir.OEQ:
  3103  				return c
  3104  			case ir.ONE:
  3105  				return s.newValue1(ssa.OpNot, types.Types[types.TBOOL], c)
  3106  			default:
  3107  				s.Fatalf("ordered complex compare %v", n.Op())
  3108  			}
  3109  		}
  3110  
  3111  		// Convert OGE and OGT into OLE and OLT.
  3112  		op := n.Op()
  3113  		switch op {
  3114  		case ir.OGE:
  3115  			op, a, b = ir.OLE, b, a
  3116  		case ir.OGT:
  3117  			op, a, b = ir.OLT, b, a
  3118  		}
  3119  		if n.X.Type().IsFloat() {
  3120  			// float comparison
  3121  			return s.newValueOrSfCall2(s.ssaOp(op, n.X.Type()), types.Types[types.TBOOL], a, b)
  3122  		}
  3123  		// integer comparison
  3124  		return s.newValue2(s.ssaOp(op, n.X.Type()), types.Types[types.TBOOL], a, b)
  3125  	case ir.OMUL:
  3126  		n := n.(*ir.BinaryExpr)
  3127  		a := s.expr(n.X)
  3128  		b := s.expr(n.Y)
  3129  		if n.Type().IsComplex() {
  3130  			mulop := ssa.OpMul64F
  3131  			addop := ssa.OpAdd64F
  3132  			subop := ssa.OpSub64F
  3133  			pt := types.FloatForComplex(n.Type()) // Could be Float32 or Float64
  3134  			wt := types.Types[types.TFLOAT64]     // Compute in Float64 to minimize cancellation error
  3135  
  3136  			areal := s.newValue1(ssa.OpComplexReal, pt, a)
  3137  			breal := s.newValue1(ssa.OpComplexReal, pt, b)
  3138  			aimag := s.newValue1(ssa.OpComplexImag, pt, a)
  3139  			bimag := s.newValue1(ssa.OpComplexImag, pt, b)
  3140  
  3141  			if pt != wt { // Widen for calculation
  3142  				areal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, areal)
  3143  				breal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, breal)
  3144  				aimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, aimag)
  3145  				bimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, bimag)
  3146  			}
  3147  
  3148  			xreal := s.newValueOrSfCall2(subop, wt, s.newValueOrSfCall2(mulop, wt, areal, breal), s.newValueOrSfCall2(mulop, wt, aimag, bimag))
  3149  			ximag := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, areal, bimag), s.newValueOrSfCall2(mulop, wt, aimag, breal))
  3150  
  3151  			if pt != wt { // Narrow to store back
  3152  				xreal = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, xreal)
  3153  				ximag = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, ximag)
  3154  			}
  3155  
  3156  			return s.newValue2(ssa.OpComplexMake, n.Type(), xreal, ximag)
  3157  		}
  3158  
  3159  		if n.Type().IsFloat() {
  3160  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3161  		}
  3162  
  3163  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3164  
  3165  	case ir.ODIV:
  3166  		n := n.(*ir.BinaryExpr)
  3167  		a := s.expr(n.X)
  3168  		b := s.expr(n.Y)
  3169  		if n.Type().IsComplex() {
  3170  			// TODO this is not executed because the front-end substitutes a runtime call.
  3171  			// That probably ought to change; with modest optimization the widen/narrow
  3172  			// conversions could all be elided in larger expression trees.
  3173  			mulop := ssa.OpMul64F
  3174  			addop := ssa.OpAdd64F
  3175  			subop := ssa.OpSub64F
  3176  			divop := ssa.OpDiv64F
  3177  			pt := types.FloatForComplex(n.Type()) // Could be Float32 or Float64
  3178  			wt := types.Types[types.TFLOAT64]     // Compute in Float64 to minimize cancellation error
  3179  
  3180  			areal := s.newValue1(ssa.OpComplexReal, pt, a)
  3181  			breal := s.newValue1(ssa.OpComplexReal, pt, b)
  3182  			aimag := s.newValue1(ssa.OpComplexImag, pt, a)
  3183  			bimag := s.newValue1(ssa.OpComplexImag, pt, b)
  3184  
  3185  			if pt != wt { // Widen for calculation
  3186  				areal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, areal)
  3187  				breal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, breal)
  3188  				aimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, aimag)
  3189  				bimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, bimag)
  3190  			}
  3191  
  3192  			denom := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, breal, breal), s.newValueOrSfCall2(mulop, wt, bimag, bimag))
  3193  			xreal := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, areal, breal), s.newValueOrSfCall2(mulop, wt, aimag, bimag))
  3194  			ximag := s.newValueOrSfCall2(subop, wt, s.newValueOrSfCall2(mulop, wt, aimag, breal), s.newValueOrSfCall2(mulop, wt, areal, bimag))
  3195  
  3196  			// TODO not sure if this is best done in wide precision or narrow
  3197  			// Double-rounding might be an issue.
  3198  			// Note that the pre-SSA implementation does the entire calculation
  3199  			// in wide format, so wide is compatible.
  3200  			xreal = s.newValueOrSfCall2(divop, wt, xreal, denom)
  3201  			ximag = s.newValueOrSfCall2(divop, wt, ximag, denom)
  3202  
  3203  			if pt != wt { // Narrow to store back
  3204  				xreal = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, xreal)
  3205  				ximag = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, ximag)
  3206  			}
  3207  			return s.newValue2(ssa.OpComplexMake, n.Type(), xreal, ximag)
  3208  		}
  3209  		if n.Type().IsFloat() {
  3210  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3211  		}
  3212  		return s.intDivide(n, a, b)
  3213  	case ir.OMOD:
  3214  		n := n.(*ir.BinaryExpr)
  3215  		a := s.expr(n.X)
  3216  		b := s.expr(n.Y)
  3217  		return s.intDivide(n, a, b)
  3218  	case ir.OADD, ir.OSUB:
  3219  		n := n.(*ir.BinaryExpr)
  3220  		a := s.expr(n.X)
  3221  		b := s.expr(n.Y)
  3222  		if n.Type().IsComplex() {
  3223  			pt := types.FloatForComplex(n.Type())
  3224  			op := s.ssaOp(n.Op(), pt)
  3225  			return s.newValue2(ssa.OpComplexMake, n.Type(),
  3226  				s.newValueOrSfCall2(op, pt, s.newValue1(ssa.OpComplexReal, pt, a), s.newValue1(ssa.OpComplexReal, pt, b)),
  3227  				s.newValueOrSfCall2(op, pt, s.newValue1(ssa.OpComplexImag, pt, a), s.newValue1(ssa.OpComplexImag, pt, b)))
  3228  		}
  3229  		if n.Type().IsFloat() {
  3230  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3231  		}
  3232  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3233  	case ir.OAND, ir.OOR, ir.OXOR:
  3234  		n := n.(*ir.BinaryExpr)
  3235  		a := s.expr(n.X)
  3236  		b := s.expr(n.Y)
  3237  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3238  	case ir.OANDNOT:
  3239  		n := n.(*ir.BinaryExpr)
  3240  		a := s.expr(n.X)
  3241  		b := s.expr(n.Y)
  3242  		b = s.newValue1(s.ssaOp(ir.OBITNOT, b.Type), b.Type, b)
  3243  		return s.newValue2(s.ssaOp(ir.OAND, n.Type()), a.Type, a, b)
  3244  	case ir.OLSH, ir.ORSH:
  3245  		n := n.(*ir.BinaryExpr)
  3246  		a := s.expr(n.X)
  3247  		b := s.expr(n.Y)
  3248  		bt := b.Type
  3249  		if bt.IsSigned() {
  3250  			cmp := s.newValue2(s.ssaOp(ir.OLE, bt), types.Types[types.TBOOL], s.zeroVal(bt), b)
  3251  			s.check(cmp, ir.Syms.Panicshift)
  3252  			bt = bt.ToUnsigned()
  3253  		}
  3254  		return s.newValue2(s.ssaShiftOp(n.Op(), n.Type(), bt), a.Type, a, b)
  3255  	case ir.OANDAND, ir.OOROR:
  3256  		// To implement OANDAND (and OOROR), we introduce a
  3257  		// new temporary variable to hold the result. The
  3258  		// variable is associated with the OANDAND node in the
  3259  		// s.vars table (normally variables are only
  3260  		// associated with ONAME nodes). We convert
  3261  		//     A && B
  3262  		// to
  3263  		//     var = A
  3264  		//     if var {
  3265  		//         var = B
  3266  		//     }
  3267  		// Using var in the subsequent block introduces the
  3268  		// necessary phi variable.
  3269  		n := n.(*ir.LogicalExpr)
  3270  		el := s.expr(n.X)
  3271  		s.vars[n] = el
  3272  
  3273  		b := s.endBlock()
  3274  		b.Kind = ssa.BlockIf
  3275  		b.SetControl(el)
  3276  		// In theory, we should set b.Likely here based on context.
  3277  		// However, gc only gives us likeliness hints
  3278  		// in a single place, for plain OIF statements,
  3279  		// and passing around context is finicky, so don't bother for now.
  3280  
  3281  		bRight := s.f.NewBlock(ssa.BlockPlain)
  3282  		bResult := s.f.NewBlock(ssa.BlockPlain)
  3283  		if n.Op() == ir.OANDAND {
  3284  			b.AddEdgeTo(bRight)
  3285  			b.AddEdgeTo(bResult)
  3286  		} else if n.Op() == ir.OOROR {
  3287  			b.AddEdgeTo(bResult)
  3288  			b.AddEdgeTo(bRight)
  3289  		}
  3290  
  3291  		s.startBlock(bRight)
  3292  		er := s.expr(n.Y)
  3293  		s.vars[n] = er
  3294  
  3295  		b = s.endBlock()
  3296  		b.AddEdgeTo(bResult)
  3297  
  3298  		s.startBlock(bResult)
  3299  		return s.variable(n, types.Types[types.TBOOL])
  3300  	case ir.OCOMPLEX:
  3301  		n := n.(*ir.BinaryExpr)
  3302  		r := s.expr(n.X)
  3303  		i := s.expr(n.Y)
  3304  		return s.newValue2(ssa.OpComplexMake, n.Type(), r, i)
  3305  
  3306  	// unary ops
  3307  	case ir.ONEG:
  3308  		n := n.(*ir.UnaryExpr)
  3309  		a := s.expr(n.X)
  3310  		if n.Type().IsComplex() {
  3311  			tp := types.FloatForComplex(n.Type())
  3312  			negop := s.ssaOp(n.Op(), tp)
  3313  			return s.newValue2(ssa.OpComplexMake, n.Type(),
  3314  				s.newValue1(negop, tp, s.newValue1(ssa.OpComplexReal, tp, a)),
  3315  				s.newValue1(negop, tp, s.newValue1(ssa.OpComplexImag, tp, a)))
  3316  		}
  3317  		return s.newValue1(s.ssaOp(n.Op(), n.Type()), a.Type, a)
  3318  	case ir.ONOT, ir.OBITNOT:
  3319  		n := n.(*ir.UnaryExpr)
  3320  		a := s.expr(n.X)
  3321  		return s.newValue1(s.ssaOp(n.Op(), n.Type()), a.Type, a)
  3322  	case ir.OIMAG, ir.OREAL:
  3323  		n := n.(*ir.UnaryExpr)
  3324  		a := s.expr(n.X)
  3325  		return s.newValue1(s.ssaOp(n.Op(), n.X.Type()), n.Type(), a)
  3326  	case ir.OPLUS:
  3327  		n := n.(*ir.UnaryExpr)
  3328  		return s.expr(n.X)
  3329  
  3330  	case ir.OADDR:
  3331  		n := n.(*ir.AddrExpr)
  3332  		return s.addr(n.X)
  3333  
  3334  	case ir.ORESULT:
  3335  		n := n.(*ir.ResultExpr)
  3336  		if s.prevCall == nil || s.prevCall.Op != ssa.OpStaticLECall && s.prevCall.Op != ssa.OpInterLECall && s.prevCall.Op != ssa.OpClosureLECall {
  3337  			panic("Expected to see a previous call")
  3338  		}
  3339  		which := n.Index
  3340  		if which == -1 {
  3341  			panic(fmt.Errorf("ORESULT %v does not match call %s", n, s.prevCall))
  3342  		}
  3343  		return s.resultOfCall(s.prevCall, which, n.Type())
  3344  
  3345  	case ir.ODEREF:
  3346  		n := n.(*ir.StarExpr)
  3347  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  3348  		return s.load(n.Type(), p)
  3349  
  3350  	case ir.ODOT:
  3351  		n := n.(*ir.SelectorExpr)
  3352  		if n.X.Op() == ir.OSTRUCTLIT {
  3353  			// All literals with nonzero fields have already been
  3354  			// rewritten during walk. Any that remain are just T{}
  3355  			// or equivalents. Use the zero value.
  3356  			if !ir.IsZero(n.X) {
  3357  				s.Fatalf("literal with nonzero value in SSA: %v", n.X)
  3358  			}
  3359  			return s.zeroVal(n.Type())
  3360  		}
  3361  		// If n is addressable and can't be represented in
  3362  		// SSA, then load just the selected field. This
  3363  		// prevents false memory dependencies in race/msan/asan
  3364  		// instrumentation.
  3365  		if ir.IsAddressable(n) && !s.canSSA(n) {
  3366  			p := s.addr(n)
  3367  			return s.load(n.Type(), p)
  3368  		}
  3369  		v := s.expr(n.X)
  3370  		return s.newValue1I(ssa.OpStructSelect, n.Type(), int64(fieldIdx(n)), v)
  3371  
  3372  	case ir.ODOTPTR:
  3373  		n := n.(*ir.SelectorExpr)
  3374  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  3375  		p = s.newValue1I(ssa.OpOffPtr, types.NewPtr(n.Type()), n.Offset(), p)
  3376  		return s.load(n.Type(), p)
  3377  
  3378  	case ir.OINDEX:
  3379  		n := n.(*ir.IndexExpr)
  3380  		switch {
  3381  		case n.X.Type().IsString():
  3382  			if n.Bounded() && ir.IsConst(n.X, constant.String) && ir.IsConst(n.Index, constant.Int) {
  3383  				// Replace "abc"[1] with 'b'.
  3384  				// Delayed until now because "abc"[1] is not an ideal constant.
  3385  				// See test/fixedbugs/issue11370.go.
  3386  				return s.newValue0I(ssa.OpConst8, types.Types[types.TUINT8], int64(int8(ir.StringVal(n.X)[ir.Int64Val(n.Index)])))
  3387  			}
  3388  			a := s.expr(n.X)
  3389  			i := s.expr(n.Index)
  3390  			len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], a)
  3391  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  3392  			ptrtyp := s.f.Config.Types.BytePtr
  3393  			ptr := s.newValue1(ssa.OpStringPtr, ptrtyp, a)
  3394  			if ir.IsConst(n.Index, constant.Int) {
  3395  				ptr = s.newValue1I(ssa.OpOffPtr, ptrtyp, ir.Int64Val(n.Index), ptr)
  3396  			} else {
  3397  				ptr = s.newValue2(ssa.OpAddPtr, ptrtyp, ptr, i)
  3398  			}
  3399  			return s.load(types.Types[types.TUINT8], ptr)
  3400  		case n.X.Type().IsSlice():
  3401  			p := s.addr(n)
  3402  			return s.load(n.X.Type().Elem(), p)
  3403  		case n.X.Type().IsArray():
  3404  			if ssa.CanSSA(n.X.Type()) {
  3405  				// SSA can handle arrays of length at most 1.
  3406  				bound := n.X.Type().NumElem()
  3407  				a := s.expr(n.X)
  3408  				i := s.expr(n.Index)
  3409  				if bound == 0 {
  3410  					// Bounds check will never succeed.  Might as well
  3411  					// use constants for the bounds check.
  3412  					z := s.constInt(types.Types[types.TINT], 0)
  3413  					s.boundsCheck(z, z, ssa.BoundsIndex, false)
  3414  					// The return value won't be live, return junk.
  3415  					// But not quite junk, in case bounds checks are turned off. See issue 48092.
  3416  					return s.zeroVal(n.Type())
  3417  				}
  3418  				len := s.constInt(types.Types[types.TINT], bound)
  3419  				s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded()) // checks i == 0
  3420  				return s.newValue1I(ssa.OpArraySelect, n.Type(), 0, a)
  3421  			}
  3422  			p := s.addr(n)
  3423  			return s.load(n.X.Type().Elem(), p)
  3424  		default:
  3425  			s.Fatalf("bad type for index %v", n.X.Type())
  3426  			return nil
  3427  		}
  3428  
  3429  	case ir.OLEN, ir.OCAP:
  3430  		n := n.(*ir.UnaryExpr)
  3431  		// Note: all constant cases are handled by the frontend. If len or cap
  3432  		// makes it here, we want the side effects of the argument. See issue 72844.
  3433  		a := s.expr(n.X)
  3434  		t := n.X.Type()
  3435  		switch {
  3436  		case t.IsSlice():
  3437  			op := ssa.OpSliceLen
  3438  			if n.Op() == ir.OCAP {
  3439  				op = ssa.OpSliceCap
  3440  			}
  3441  			return s.newValue1(op, types.Types[types.TINT], a)
  3442  		case t.IsString(): // string; not reachable for OCAP
  3443  			return s.newValue1(ssa.OpStringLen, types.Types[types.TINT], a)
  3444  		case t.IsMap(), t.IsChan():
  3445  			return s.referenceTypeBuiltin(n, a)
  3446  		case t.IsArray():
  3447  			return s.constInt(types.Types[types.TINT], t.NumElem())
  3448  		case t.IsPtr() && t.Elem().IsArray():
  3449  			return s.constInt(types.Types[types.TINT], t.Elem().NumElem())
  3450  		default:
  3451  			s.Fatalf("bad type in len/cap: %v", t)
  3452  			return nil
  3453  		}
  3454  
  3455  	case ir.OSPTR:
  3456  		n := n.(*ir.UnaryExpr)
  3457  		a := s.expr(n.X)
  3458  		if n.X.Type().IsSlice() {
  3459  			if n.Bounded() {
  3460  				return s.newValue1(ssa.OpSlicePtr, n.Type(), a)
  3461  			}
  3462  			return s.newValue1(ssa.OpSlicePtrUnchecked, n.Type(), a)
  3463  		} else {
  3464  			return s.newValue1(ssa.OpStringPtr, n.Type(), a)
  3465  		}
  3466  
  3467  	case ir.OITAB:
  3468  		n := n.(*ir.UnaryExpr)
  3469  		a := s.expr(n.X)
  3470  		return s.newValue1(ssa.OpITab, n.Type(), a)
  3471  
  3472  	case ir.OIDATA:
  3473  		n := n.(*ir.UnaryExpr)
  3474  		a := s.expr(n.X)
  3475  		return s.newValue1(ssa.OpIData, n.Type(), a)
  3476  
  3477  	case ir.OMAKEFACE:
  3478  		n := n.(*ir.BinaryExpr)
  3479  		tab := s.expr(n.X)
  3480  		data := s.expr(n.Y)
  3481  		return s.newValue2(ssa.OpIMake, n.Type(), tab, data)
  3482  
  3483  	case ir.OSLICEHEADER:
  3484  		n := n.(*ir.SliceHeaderExpr)
  3485  		p := s.expr(n.Ptr)
  3486  		l := s.expr(n.Len)
  3487  		c := s.expr(n.Cap)
  3488  		return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)
  3489  
  3490  	case ir.OSTRINGHEADER:
  3491  		n := n.(*ir.StringHeaderExpr)
  3492  		p := s.expr(n.Ptr)
  3493  		l := s.expr(n.Len)
  3494  		return s.newValue2(ssa.OpStringMake, n.Type(), p, l)
  3495  
  3496  	case ir.OSLICE, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR:
  3497  		n := n.(*ir.SliceExpr)
  3498  		check := s.checkPtrEnabled && n.Op() == ir.OSLICE3ARR && n.X.Op() == ir.OCONVNOP && n.X.(*ir.ConvExpr).X.Type().IsUnsafePtr()
  3499  		v := s.exprCheckPtr(n.X, !check)
  3500  		var i, j, k *ssa.Value
  3501  		if n.Low != nil {
  3502  			i = s.expr(n.Low)
  3503  		}
  3504  		if n.High != nil {
  3505  			j = s.expr(n.High)
  3506  		}
  3507  		if n.Max != nil {
  3508  			k = s.expr(n.Max)
  3509  		}
  3510  		p, l, c := s.slice(v, i, j, k, n.Bounded())
  3511  		if check {
  3512  			// Emit checkptr instrumentation after bound check to prevent false positive, see #46938.
  3513  			s.checkPtrAlignment(n.X.(*ir.ConvExpr), v, s.conv(n.Max, k, k.Type, types.Types[types.TUINTPTR]))
  3514  		}
  3515  		return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)
  3516  
  3517  	case ir.OSLICESTR:
  3518  		n := n.(*ir.SliceExpr)
  3519  		v := s.expr(n.X)
  3520  		var i, j *ssa.Value
  3521  		if n.Low != nil {
  3522  			i = s.expr(n.Low)
  3523  		}
  3524  		if n.High != nil {
  3525  			j = s.expr(n.High)
  3526  		}
  3527  		p, l, _ := s.slice(v, i, j, nil, n.Bounded())
  3528  		return s.newValue2(ssa.OpStringMake, n.Type(), p, l)
  3529  
  3530  	case ir.OSLICE2ARRPTR:
  3531  		// if arrlen > slice.len {
  3532  		//   panic(...)
  3533  		// }
  3534  		// slice.ptr
  3535  		n := n.(*ir.ConvExpr)
  3536  		v := s.expr(n.X)
  3537  		nelem := n.Type().Elem().NumElem()
  3538  		arrlen := s.constInt(types.Types[types.TINT], nelem)
  3539  		cap := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], v)
  3540  		s.boundsCheck(arrlen, cap, ssa.BoundsConvert, false)
  3541  		op := ssa.OpSlicePtr
  3542  		if nelem == 0 {
  3543  			op = ssa.OpSlicePtrUnchecked
  3544  		}
  3545  		return s.newValue1(op, n.Type(), v)
  3546  
  3547  	case ir.OCALLFUNC:
  3548  		n := n.(*ir.CallExpr)
  3549  		if ir.IsIntrinsicCall(n) {
  3550  			return s.intrinsicCall(n)
  3551  		}
  3552  		fallthrough
  3553  
  3554  	case ir.OCALLINTER:
  3555  		n := n.(*ir.CallExpr)
  3556  		return s.callResult(n, callNormal)
  3557  
  3558  	case ir.OGETG:
  3559  		n := n.(*ir.CallExpr)
  3560  		return s.newValue1(ssa.OpGetG, n.Type(), s.mem())
  3561  
  3562  	case ir.OGETCALLERSP:
  3563  		n := n.(*ir.CallExpr)
  3564  		return s.newValue1(ssa.OpGetCallerSP, n.Type(), s.mem())
  3565  
  3566  	case ir.OAPPEND:
  3567  		return s.append(n.(*ir.CallExpr), false)
  3568  
  3569  	case ir.OMIN, ir.OMAX:
  3570  		return s.minMax(n.(*ir.CallExpr))
  3571  
  3572  	case ir.OSTRUCTLIT, ir.OARRAYLIT:
  3573  		// All literals with nonzero fields have already been
  3574  		// rewritten during walk. Any that remain are just T{}
  3575  		// or equivalents. Use the zero value.
  3576  		n := n.(*ir.CompLitExpr)
  3577  		if !ir.IsZero(n) {
  3578  			s.Fatalf("literal with nonzero value in SSA: %v", n)
  3579  		}
  3580  		return s.zeroVal(n.Type())
  3581  
  3582  	case ir.ONEW:
  3583  		n := n.(*ir.UnaryExpr)
  3584  		var rtype *ssa.Value
  3585  		if x, ok := n.X.(*ir.DynamicType); ok && x.Op() == ir.ODYNAMICTYPE {
  3586  			rtype = s.expr(x.RType)
  3587  		}
  3588  		return s.newObject(n.Type().Elem(), rtype)
  3589  
  3590  	case ir.OUNSAFEADD:
  3591  		n := n.(*ir.BinaryExpr)
  3592  		ptr := s.expr(n.X)
  3593  		len := s.expr(n.Y)
  3594  
  3595  		// Force len to uintptr to prevent misuse of garbage bits in the
  3596  		// upper part of the register (#48536).
  3597  		len = s.conv(n, len, len.Type, types.Types[types.TUINTPTR])
  3598  
  3599  		return s.newValue2(ssa.OpAddPtr, n.Type(), ptr, len)
  3600  
  3601  	default:
  3602  		s.Fatalf("unhandled expr %v", n.Op())
  3603  		return nil
  3604  	}
  3605  }
  3606  
  3607  func (s *state) resultOfCall(c *ssa.Value, which int64, t *types.Type) *ssa.Value {
  3608  	aux := c.Aux.(*ssa.AuxCall)
  3609  	pa := aux.ParamAssignmentForResult(which)
  3610  	// TODO(register args) determine if in-memory TypeOK is better loaded early from SelectNAddr or later when SelectN is expanded.
  3611  	// SelectN is better for pattern-matching and possible call-aware analysis we might want to do in the future.
  3612  	if len(pa.Registers) == 0 && !ssa.CanSSA(t) {
  3613  		addr := s.newValue1I(ssa.OpSelectNAddr, types.NewPtr(t), which, c)
  3614  		return s.rawLoad(t, addr)
  3615  	}
  3616  	return s.newValue1I(ssa.OpSelectN, t, which, c)
  3617  }
  3618  
  3619  func (s *state) resultAddrOfCall(c *ssa.Value, which int64, t *types.Type) *ssa.Value {
  3620  	aux := c.Aux.(*ssa.AuxCall)
  3621  	pa := aux.ParamAssignmentForResult(which)
  3622  	if len(pa.Registers) == 0 {
  3623  		return s.newValue1I(ssa.OpSelectNAddr, types.NewPtr(t), which, c)
  3624  	}
  3625  	_, addr := s.temp(c.Pos, t)
  3626  	rval := s.newValue1I(ssa.OpSelectN, t, which, c)
  3627  	s.vars[memVar] = s.newValue3Apos(ssa.OpStore, types.TypeMem, t, addr, rval, s.mem(), false)
  3628  	return addr
  3629  }
  3630  
  3631  // append converts an OAPPEND node to SSA.
  3632  // If inplace is false, it converts the OAPPEND expression n to an ssa.Value,
  3633  // adds it to s, and returns the Value.
  3634  // If inplace is true, it writes the result of the OAPPEND expression n
  3635  // back to the slice being appended to, and returns nil.
  3636  // inplace MUST be set to false if the slice can be SSA'd.
  3637  // Note: this code only handles fixed-count appends. Dotdotdot appends
  3638  // have already been rewritten at this point (by walk).
  3639  func (s *state) append(n *ir.CallExpr, inplace bool) *ssa.Value {
  3640  	// If inplace is false, process as expression "append(s, e1, e2, e3)":
  3641  	//
  3642  	// ptr, len, cap := s
  3643  	// len += 3
  3644  	// if uint(len) > uint(cap) {
  3645  	//     ptr, len, cap = growslice(ptr, len, cap, 3, typ)
  3646  	//     Note that len is unmodified by growslice.
  3647  	// }
  3648  	// // with write barriers, if needed:
  3649  	// *(ptr+(len-3)) = e1
  3650  	// *(ptr+(len-2)) = e2
  3651  	// *(ptr+(len-1)) = e3
  3652  	// return makeslice(ptr, len, cap)
  3653  	//
  3654  	//
  3655  	// If inplace is true, process as statement "s = append(s, e1, e2, e3)":
  3656  	//
  3657  	// a := &s
  3658  	// ptr, len, cap := s
  3659  	// len += 3
  3660  	// if uint(len) > uint(cap) {
  3661  	//    ptr, len, cap = growslice(ptr, len, cap, 3, typ)
  3662  	//    vardef(a)    // if necessary, advise liveness we are writing a new a
  3663  	//    *a.cap = cap // write before ptr to avoid a spill
  3664  	//    *a.ptr = ptr // with write barrier
  3665  	// }
  3666  	// *a.len = len
  3667  	// // with write barriers, if needed:
  3668  	// *(ptr+(len-3)) = e1
  3669  	// *(ptr+(len-2)) = e2
  3670  	// *(ptr+(len-1)) = e3
  3671  
  3672  	et := n.Type().Elem()
  3673  	pt := types.NewPtr(et)
  3674  
  3675  	// Evaluate slice
  3676  	sn := n.Args[0] // the slice node is the first in the list
  3677  	var slice, addr *ssa.Value
  3678  	if inplace {
  3679  		addr = s.addr(sn)
  3680  		slice = s.load(n.Type(), addr)
  3681  	} else {
  3682  		slice = s.expr(sn)
  3683  	}
  3684  
  3685  	// Allocate new blocks
  3686  	grow := s.f.NewBlock(ssa.BlockPlain)
  3687  	assign := s.f.NewBlock(ssa.BlockPlain)
  3688  
  3689  	// Decomposse input slice.
  3690  	p := s.newValue1(ssa.OpSlicePtr, pt, slice)
  3691  	l := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], slice)
  3692  	c := s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], slice)
  3693  
  3694  	// Add number of new elements to length.
  3695  	nargs := s.constInt(types.Types[types.TINT], int64(len(n.Args)-1))
  3696  	oldLen := l
  3697  	l = s.newValue2(s.ssaOp(ir.OADD, types.Types[types.TINT]), types.Types[types.TINT], l, nargs)
  3698  
  3699  	// Decide if we need to grow
  3700  	cmp := s.newValue2(s.ssaOp(ir.OLT, types.Types[types.TUINT]), types.Types[types.TBOOL], c, l)
  3701  
  3702  	// Record values of ptr/len/cap before branch.
  3703  	s.vars[ptrVar] = p
  3704  	s.vars[lenVar] = l
  3705  	if !inplace {
  3706  		s.vars[capVar] = c
  3707  	}
  3708  
  3709  	b := s.endBlock()
  3710  	b.Kind = ssa.BlockIf
  3711  	b.Likely = ssa.BranchUnlikely
  3712  	b.SetControl(cmp)
  3713  	b.AddEdgeTo(grow)
  3714  	b.AddEdgeTo(assign)
  3715  
  3716  	// If the result of the append does not escape, we can use
  3717  	// a stack-allocated backing store if len is small enough.
  3718  	// A stack-allocated backing store could be used at every
  3719  	// append that qualifies, but we limit it in some cases to
  3720  	// avoid wasted code and stack space.
  3721  	// TODO: handle ... append case.
  3722  	maxStackSize := int64(base.Debug.VariableMakeThreshold)
  3723  	if !inplace && n.Esc() == ir.EscNone && et.Size() > 0 && et.Size() <= maxStackSize && base.Flag.N == 0 && base.VariableMakeHash.MatchPos(n.Pos(), nil) && !s.appendTargets[sn] {
  3724  		// if l <= K {
  3725  		//   if !used {
  3726  		//     if oldLen == 0 {
  3727  		//       var store [K]T
  3728  		//       s = store[:l:K]
  3729  		//       used = true
  3730  		//     }
  3731  		//   }
  3732  		// }
  3733  		// ... if we didn't use the stack backing store, call growslice ...
  3734  		//
  3735  		// oldLen==0 is not strictly necessary, but requiring it means
  3736  		// we don't have to worry about copying existing elements.
  3737  		// Allowing oldLen>0 would add complication. Worth it? I would guess not.
  3738  		//
  3739  		// TODO: instead of the used boolean, we could insist that this only applies
  3740  		// to monotonic slices, those which once they have >0 entries never go back
  3741  		// to 0 entries. Then oldLen==0 is enough.
  3742  		//
  3743  		// We also do this for append(x, ...) once for every x.
  3744  		// It is ok to do it more often, but it is probably helpful only for
  3745  		// the first instance. TODO: this could use more tuning. Using ir.Node
  3746  		// as the key works for *ir.Name instances but probably nothing else.
  3747  		if s.appendTargets == nil {
  3748  			s.appendTargets = map[ir.Node]bool{}
  3749  		}
  3750  		s.appendTargets[sn] = true
  3751  
  3752  		K := maxStackSize / et.Size() // rounds down
  3753  		KT := types.NewArray(et, K)
  3754  		KT.SetNoalg(true)
  3755  		types.CalcArraySize(KT)
  3756  		// Align more than naturally for the type KT. See issue 73199.
  3757  		align := types.NewArray(types.Types[types.TUINTPTR], 0)
  3758  		types.CalcArraySize(align)
  3759  		storeTyp := types.NewStruct([]*types.Field{
  3760  			{Sym: types.BlankSym, Type: align},
  3761  			{Sym: types.BlankSym, Type: KT},
  3762  		})
  3763  		storeTyp.SetNoalg(true)
  3764  		types.CalcStructSize(storeTyp)
  3765  
  3766  		usedTestBlock := s.f.NewBlock(ssa.BlockPlain)
  3767  		oldLenTestBlock := s.f.NewBlock(ssa.BlockPlain)
  3768  		bodyBlock := s.f.NewBlock(ssa.BlockPlain)
  3769  		growSlice := s.f.NewBlock(ssa.BlockPlain)
  3770  
  3771  		// Make "used" boolean.
  3772  		tBool := types.Types[types.TBOOL]
  3773  		used := typecheck.TempAt(n.Pos(), s.curfn, tBool)
  3774  		s.defvars[s.f.Entry.ID][used] = s.constBool(false) // initialize this variable at fn entry
  3775  
  3776  		// Make backing store variable.
  3777  		tInt := types.Types[types.TINT]
  3778  		backingStore := typecheck.TempAt(n.Pos(), s.curfn, storeTyp)
  3779  		backingStore.SetAddrtaken(true)
  3780  
  3781  		// if l <= K
  3782  		s.startBlock(grow)
  3783  		kTest := s.newValue2(s.ssaOp(ir.OLE, tInt), tBool, l, s.constInt(tInt, K))
  3784  		b := s.endBlock()
  3785  		b.Kind = ssa.BlockIf
  3786  		b.SetControl(kTest)
  3787  		b.AddEdgeTo(usedTestBlock)
  3788  		b.AddEdgeTo(growSlice)
  3789  		b.Likely = ssa.BranchLikely
  3790  
  3791  		// if !used
  3792  		s.startBlock(usedTestBlock)
  3793  		usedTest := s.newValue1(ssa.OpNot, tBool, s.expr(used))
  3794  		b = s.endBlock()
  3795  		b.Kind = ssa.BlockIf
  3796  		b.SetControl(usedTest)
  3797  		b.AddEdgeTo(oldLenTestBlock)
  3798  		b.AddEdgeTo(growSlice)
  3799  		b.Likely = ssa.BranchLikely
  3800  
  3801  		// if oldLen == 0
  3802  		s.startBlock(oldLenTestBlock)
  3803  		oldLenTest := s.newValue2(s.ssaOp(ir.OEQ, tInt), tBool, oldLen, s.constInt(tInt, 0))
  3804  		b = s.endBlock()
  3805  		b.Kind = ssa.BlockIf
  3806  		b.SetControl(oldLenTest)
  3807  		b.AddEdgeTo(bodyBlock)
  3808  		b.AddEdgeTo(growSlice)
  3809  		b.Likely = ssa.BranchLikely
  3810  
  3811  		// var store struct { _ [0]uintptr; arr [K]T }
  3812  		s.startBlock(bodyBlock)
  3813  		if et.HasPointers() {
  3814  			s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, backingStore, s.mem())
  3815  		}
  3816  		addr := s.addr(backingStore)
  3817  		s.zero(storeTyp, addr)
  3818  
  3819  		// s = store.arr[:l:K]
  3820  		s.vars[ptrVar] = addr
  3821  		s.vars[lenVar] = l // nargs would also be ok because of the oldLen==0 test.
  3822  		s.vars[capVar] = s.constInt(tInt, K)
  3823  
  3824  		// used = true
  3825  		s.assign(used, s.constBool(true), false, 0)
  3826  		b = s.endBlock()
  3827  		b.AddEdgeTo(assign)
  3828  
  3829  		// New block to use for growslice call.
  3830  		grow = growSlice
  3831  	}
  3832  
  3833  	// Call growslice
  3834  	s.startBlock(grow)
  3835  	taddr := s.expr(n.Fun)
  3836  	r := s.rtcall(ir.Syms.Growslice, true, []*types.Type{n.Type()}, p, l, c, nargs, taddr)
  3837  
  3838  	// Decompose output slice
  3839  	p = s.newValue1(ssa.OpSlicePtr, pt, r[0])
  3840  	l = s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], r[0])
  3841  	c = s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], r[0])
  3842  
  3843  	s.vars[ptrVar] = p
  3844  	s.vars[lenVar] = l
  3845  	s.vars[capVar] = c
  3846  	if inplace {
  3847  		if sn.Op() == ir.ONAME {
  3848  			sn := sn.(*ir.Name)
  3849  			if sn.Class != ir.PEXTERN {
  3850  				// Tell liveness we're about to build a new slice
  3851  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, sn, s.mem())
  3852  			}
  3853  		}
  3854  		capaddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, types.SliceCapOffset, addr)
  3855  		s.store(types.Types[types.TINT], capaddr, c)
  3856  		s.store(pt, addr, p)
  3857  	}
  3858  
  3859  	b = s.endBlock()
  3860  	b.AddEdgeTo(assign)
  3861  
  3862  	// assign new elements to slots
  3863  	s.startBlock(assign)
  3864  	p = s.variable(ptrVar, pt)                      // generates phi for ptr
  3865  	l = s.variable(lenVar, types.Types[types.TINT]) // generates phi for len
  3866  	if !inplace {
  3867  		c = s.variable(capVar, types.Types[types.TINT]) // generates phi for cap
  3868  	}
  3869  
  3870  	if inplace {
  3871  		// Update length in place.
  3872  		// We have to wait until here to make sure growslice succeeded.
  3873  		lenaddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, types.SliceLenOffset, addr)
  3874  		s.store(types.Types[types.TINT], lenaddr, l)
  3875  	}
  3876  
  3877  	// Evaluate args
  3878  	type argRec struct {
  3879  		// if store is true, we're appending the value v.  If false, we're appending the
  3880  		// value at *v.
  3881  		v     *ssa.Value
  3882  		store bool
  3883  	}
  3884  	args := make([]argRec, 0, len(n.Args[1:]))
  3885  	for _, n := range n.Args[1:] {
  3886  		if ssa.CanSSA(n.Type()) {
  3887  			args = append(args, argRec{v: s.expr(n), store: true})
  3888  		} else {
  3889  			v := s.addr(n)
  3890  			args = append(args, argRec{v: v})
  3891  		}
  3892  	}
  3893  
  3894  	// Write args into slice.
  3895  	oldLen = s.newValue2(s.ssaOp(ir.OSUB, types.Types[types.TINT]), types.Types[types.TINT], l, nargs)
  3896  	p2 := s.newValue2(ssa.OpPtrIndex, pt, p, oldLen)
  3897  	for i, arg := range args {
  3898  		addr := s.newValue2(ssa.OpPtrIndex, pt, p2, s.constInt(types.Types[types.TINT], int64(i)))
  3899  		if arg.store {
  3900  			s.storeType(et, addr, arg.v, 0, true)
  3901  		} else {
  3902  			s.move(et, addr, arg.v)
  3903  		}
  3904  	}
  3905  
  3906  	// The following deletions have no practical effect at this time
  3907  	// because state.vars has been reset by the preceding state.startBlock.
  3908  	// They only enforce the fact that these variables are no longer need in
  3909  	// the current scope.
  3910  	delete(s.vars, ptrVar)
  3911  	delete(s.vars, lenVar)
  3912  	if !inplace {
  3913  		delete(s.vars, capVar)
  3914  	}
  3915  
  3916  	// make result
  3917  	if inplace {
  3918  		return nil
  3919  	}
  3920  	return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)
  3921  }
  3922  
  3923  // minMax converts an OMIN/OMAX builtin call into SSA.
  3924  func (s *state) minMax(n *ir.CallExpr) *ssa.Value {
  3925  	// The OMIN/OMAX builtin is variadic, but its semantics are
  3926  	// equivalent to left-folding a binary min/max operation across the
  3927  	// arguments list.
  3928  	fold := func(op func(x, a *ssa.Value) *ssa.Value) *ssa.Value {
  3929  		x := s.expr(n.Args[0])
  3930  		for _, arg := range n.Args[1:] {
  3931  			x = op(x, s.expr(arg))
  3932  		}
  3933  		return x
  3934  	}
  3935  
  3936  	typ := n.Type()
  3937  
  3938  	if typ.IsFloat() || typ.IsString() {
  3939  		// min/max semantics for floats are tricky because of NaNs and
  3940  		// negative zero. Some architectures have instructions which
  3941  		// we can use to generate the right result. For others we must
  3942  		// call into the runtime instead.
  3943  		//
  3944  		// Strings are conceptually simpler, but we currently desugar
  3945  		// string comparisons during walk, not ssagen.
  3946  
  3947  		if typ.IsFloat() {
  3948  			hasIntrinsic := false
  3949  			switch Arch.LinkArch.Family {
  3950  			case sys.AMD64, sys.ARM64, sys.Loong64, sys.RISCV64, sys.S390X:
  3951  				hasIntrinsic = true
  3952  			case sys.PPC64:
  3953  				hasIntrinsic = buildcfg.GOPPC64 >= 9
  3954  			}
  3955  
  3956  			if hasIntrinsic {
  3957  				var op ssa.Op
  3958  				switch {
  3959  				case typ.Kind() == types.TFLOAT64 && n.Op() == ir.OMIN:
  3960  					op = ssa.OpMin64F
  3961  				case typ.Kind() == types.TFLOAT64 && n.Op() == ir.OMAX:
  3962  					op = ssa.OpMax64F
  3963  				case typ.Kind() == types.TFLOAT32 && n.Op() == ir.OMIN:
  3964  					op = ssa.OpMin32F
  3965  				case typ.Kind() == types.TFLOAT32 && n.Op() == ir.OMAX:
  3966  					op = ssa.OpMax32F
  3967  				}
  3968  				return fold(func(x, a *ssa.Value) *ssa.Value {
  3969  					return s.newValue2(op, typ, x, a)
  3970  				})
  3971  			}
  3972  		}
  3973  		var name string
  3974  		switch typ.Kind() {
  3975  		case types.TFLOAT32:
  3976  			switch n.Op() {
  3977  			case ir.OMIN:
  3978  				name = "fmin32"
  3979  			case ir.OMAX:
  3980  				name = "fmax32"
  3981  			}
  3982  		case types.TFLOAT64:
  3983  			switch n.Op() {
  3984  			case ir.OMIN:
  3985  				name = "fmin64"
  3986  			case ir.OMAX:
  3987  				name = "fmax64"
  3988  			}
  3989  		case types.TSTRING:
  3990  			switch n.Op() {
  3991  			case ir.OMIN:
  3992  				name = "strmin"
  3993  			case ir.OMAX:
  3994  				name = "strmax"
  3995  			}
  3996  		}
  3997  		fn := typecheck.LookupRuntimeFunc(name)
  3998  
  3999  		return fold(func(x, a *ssa.Value) *ssa.Value {
  4000  			return s.rtcall(fn, true, []*types.Type{typ}, x, a)[0]
  4001  		})
  4002  	}
  4003  
  4004  	if typ.IsInteger() {
  4005  		if Arch.LinkArch.Family == sys.RISCV64 && buildcfg.GORISCV64 >= 22 && typ.Size() == 8 {
  4006  			var op ssa.Op
  4007  			switch {
  4008  			case typ.IsSigned() && n.Op() == ir.OMIN:
  4009  				op = ssa.OpMin64
  4010  			case typ.IsSigned() && n.Op() == ir.OMAX:
  4011  				op = ssa.OpMax64
  4012  			case typ.IsUnsigned() && n.Op() == ir.OMIN:
  4013  				op = ssa.OpMin64u
  4014  			case typ.IsUnsigned() && n.Op() == ir.OMAX:
  4015  				op = ssa.OpMax64u
  4016  			}
  4017  			return fold(func(x, a *ssa.Value) *ssa.Value {
  4018  				return s.newValue2(op, typ, x, a)
  4019  			})
  4020  		}
  4021  	}
  4022  
  4023  	lt := s.ssaOp(ir.OLT, typ)
  4024  
  4025  	return fold(func(x, a *ssa.Value) *ssa.Value {
  4026  		switch n.Op() {
  4027  		case ir.OMIN:
  4028  			// a < x ? a : x
  4029  			return s.ternary(s.newValue2(lt, types.Types[types.TBOOL], a, x), a, x)
  4030  		case ir.OMAX:
  4031  			// x < a ? a : x
  4032  			return s.ternary(s.newValue2(lt, types.Types[types.TBOOL], x, a), a, x)
  4033  		}
  4034  		panic("unreachable")
  4035  	})
  4036  }
  4037  
  4038  // ternary emits code to evaluate cond ? x : y.
  4039  func (s *state) ternary(cond, x, y *ssa.Value) *ssa.Value {
  4040  	// Note that we need a new ternaryVar each time (unlike okVar where we can
  4041  	// reuse the variable) because it might have a different type every time.
  4042  	ternaryVar := ssaMarker("ternary")
  4043  
  4044  	bThen := s.f.NewBlock(ssa.BlockPlain)
  4045  	bElse := s.f.NewBlock(ssa.BlockPlain)
  4046  	bEnd := s.f.NewBlock(ssa.BlockPlain)
  4047  
  4048  	b := s.endBlock()
  4049  	b.Kind = ssa.BlockIf
  4050  	b.SetControl(cond)
  4051  	b.AddEdgeTo(bThen)
  4052  	b.AddEdgeTo(bElse)
  4053  
  4054  	s.startBlock(bThen)
  4055  	s.vars[ternaryVar] = x
  4056  	s.endBlock().AddEdgeTo(bEnd)
  4057  
  4058  	s.startBlock(bElse)
  4059  	s.vars[ternaryVar] = y
  4060  	s.endBlock().AddEdgeTo(bEnd)
  4061  
  4062  	s.startBlock(bEnd)
  4063  	r := s.variable(ternaryVar, x.Type)
  4064  	delete(s.vars, ternaryVar)
  4065  	return r
  4066  }
  4067  
  4068  // condBranch evaluates the boolean expression cond and branches to yes
  4069  // if cond is true and no if cond is false.
  4070  // This function is intended to handle && and || better than just calling
  4071  // s.expr(cond) and branching on the result.
  4072  func (s *state) condBranch(cond ir.Node, yes, no *ssa.Block, likely int8) {
  4073  	switch cond.Op() {
  4074  	case ir.OANDAND:
  4075  		cond := cond.(*ir.LogicalExpr)
  4076  		mid := s.f.NewBlock(ssa.BlockPlain)
  4077  		s.stmtList(cond.Init())
  4078  		s.condBranch(cond.X, mid, no, max(likely, 0))
  4079  		s.startBlock(mid)
  4080  		s.condBranch(cond.Y, yes, no, likely)
  4081  		return
  4082  		// Note: if likely==1, then both recursive calls pass 1.
  4083  		// If likely==-1, then we don't have enough information to decide
  4084  		// whether the first branch is likely or not. So we pass 0 for
  4085  		// the likeliness of the first branch.
  4086  		// TODO: have the frontend give us branch prediction hints for
  4087  		// OANDAND and OOROR nodes (if it ever has such info).
  4088  	case ir.OOROR:
  4089  		cond := cond.(*ir.LogicalExpr)
  4090  		mid := s.f.NewBlock(ssa.BlockPlain)
  4091  		s.stmtList(cond.Init())
  4092  		s.condBranch(cond.X, yes, mid, min(likely, 0))
  4093  		s.startBlock(mid)
  4094  		s.condBranch(cond.Y, yes, no, likely)
  4095  		return
  4096  		// Note: if likely==-1, then both recursive calls pass -1.
  4097  		// If likely==1, then we don't have enough info to decide
  4098  		// the likelihood of the first branch.
  4099  	case ir.ONOT:
  4100  		cond := cond.(*ir.UnaryExpr)
  4101  		s.stmtList(cond.Init())
  4102  		s.condBranch(cond.X, no, yes, -likely)
  4103  		return
  4104  	case ir.OCONVNOP:
  4105  		cond := cond.(*ir.ConvExpr)
  4106  		s.stmtList(cond.Init())
  4107  		s.condBranch(cond.X, yes, no, likely)
  4108  		return
  4109  	}
  4110  	c := s.expr(cond)
  4111  	b := s.endBlock()
  4112  	b.Kind = ssa.BlockIf
  4113  	b.SetControl(c)
  4114  	b.Likely = ssa.BranchPrediction(likely) // gc and ssa both use -1/0/+1 for likeliness
  4115  	b.AddEdgeTo(yes)
  4116  	b.AddEdgeTo(no)
  4117  }
  4118  
  4119  type skipMask uint8
  4120  
  4121  const (
  4122  	skipPtr skipMask = 1 << iota
  4123  	skipLen
  4124  	skipCap
  4125  )
  4126  
  4127  // assign does left = right.
  4128  // Right has already been evaluated to ssa, left has not.
  4129  // If deref is true, then we do left = *right instead (and right has already been nil-checked).
  4130  // If deref is true and right == nil, just do left = 0.
  4131  // skip indicates assignments (at the top level) that can be avoided.
  4132  // mayOverlap indicates whether left&right might partially overlap in memory. Default is false.
  4133  func (s *state) assign(left ir.Node, right *ssa.Value, deref bool, skip skipMask) {
  4134  	s.assignWhichMayOverlap(left, right, deref, skip, false)
  4135  }
  4136  func (s *state) assignWhichMayOverlap(left ir.Node, right *ssa.Value, deref bool, skip skipMask, mayOverlap bool) {
  4137  	if left.Op() == ir.ONAME && ir.IsBlank(left) {
  4138  		return
  4139  	}
  4140  	t := left.Type()
  4141  	types.CalcSize(t)
  4142  	if s.canSSA(left) {
  4143  		if deref {
  4144  			s.Fatalf("can SSA LHS %v but not RHS %s", left, right)
  4145  		}
  4146  		if left.Op() == ir.ODOT {
  4147  			// We're assigning to a field of an ssa-able value.
  4148  			// We need to build a new structure with the new value for the
  4149  			// field we're assigning and the old values for the other fields.
  4150  			// For instance:
  4151  			//   type T struct {a, b, c int}
  4152  			//   var T x
  4153  			//   x.b = 5
  4154  			// For the x.b = 5 assignment we want to generate x = T{x.a, 5, x.c}
  4155  
  4156  			// Grab information about the structure type.
  4157  			left := left.(*ir.SelectorExpr)
  4158  			t := left.X.Type()
  4159  			nf := t.NumFields()
  4160  			idx := fieldIdx(left)
  4161  
  4162  			// Grab old value of structure.
  4163  			old := s.expr(left.X)
  4164  
  4165  			// Make new structure.
  4166  			new := s.newValue0(ssa.OpStructMake, t)
  4167  
  4168  			// Add fields as args.
  4169  			for i := 0; i < nf; i++ {
  4170  				if i == idx {
  4171  					new.AddArg(right)
  4172  				} else {
  4173  					new.AddArg(s.newValue1I(ssa.OpStructSelect, t.FieldType(i), int64(i), old))
  4174  				}
  4175  			}
  4176  
  4177  			// Recursively assign the new value we've made to the base of the dot op.
  4178  			s.assign(left.X, new, false, 0)
  4179  			// TODO: do we need to update named values here?
  4180  			return
  4181  		}
  4182  		if left.Op() == ir.OINDEX && left.(*ir.IndexExpr).X.Type().IsArray() {
  4183  			left := left.(*ir.IndexExpr)
  4184  			s.pushLine(left.Pos())
  4185  			defer s.popLine()
  4186  			// We're assigning to an element of an ssa-able array.
  4187  			// a[i] = v
  4188  			t := left.X.Type()
  4189  			n := t.NumElem()
  4190  
  4191  			i := s.expr(left.Index) // index
  4192  			if n == 0 {
  4193  				// The bounds check must fail.  Might as well
  4194  				// ignore the actual index and just use zeros.
  4195  				z := s.constInt(types.Types[types.TINT], 0)
  4196  				s.boundsCheck(z, z, ssa.BoundsIndex, false)
  4197  				return
  4198  			}
  4199  			if n != 1 {
  4200  				s.Fatalf("assigning to non-1-length array")
  4201  			}
  4202  			// Rewrite to a = [1]{v}
  4203  			len := s.constInt(types.Types[types.TINT], 1)
  4204  			s.boundsCheck(i, len, ssa.BoundsIndex, false) // checks i == 0
  4205  			v := s.newValue1(ssa.OpArrayMake1, t, right)
  4206  			s.assign(left.X, v, false, 0)
  4207  			return
  4208  		}
  4209  		left := left.(*ir.Name)
  4210  		// Update variable assignment.
  4211  		s.vars[left] = right
  4212  		s.addNamedValue(left, right)
  4213  		return
  4214  	}
  4215  
  4216  	// If this assignment clobbers an entire local variable, then emit
  4217  	// OpVarDef so liveness analysis knows the variable is redefined.
  4218  	if base, ok := clobberBase(left).(*ir.Name); ok && base.OnStack() && skip == 0 && (t.HasPointers() || ssa.IsMergeCandidate(base)) {
  4219  		s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, base, s.mem(), !ir.IsAutoTmp(base))
  4220  	}
  4221  
  4222  	// Left is not ssa-able. Compute its address.
  4223  	addr := s.addr(left)
  4224  	if ir.IsReflectHeaderDataField(left) {
  4225  		// Package unsafe's documentation says storing pointers into
  4226  		// reflect.SliceHeader and reflect.StringHeader's Data fields
  4227  		// is valid, even though they have type uintptr (#19168).
  4228  		// Mark it pointer type to signal the writebarrier pass to
  4229  		// insert a write barrier.
  4230  		t = types.Types[types.TUNSAFEPTR]
  4231  	}
  4232  	if deref {
  4233  		// Treat as a mem->mem move.
  4234  		if right == nil {
  4235  			s.zero(t, addr)
  4236  		} else {
  4237  			s.moveWhichMayOverlap(t, addr, right, mayOverlap)
  4238  		}
  4239  		return
  4240  	}
  4241  	// Treat as a store.
  4242  	s.storeType(t, addr, right, skip, !ir.IsAutoTmp(left))
  4243  }
  4244  
  4245  // zeroVal returns the zero value for type t.
  4246  func (s *state) zeroVal(t *types.Type) *ssa.Value {
  4247  	switch {
  4248  	case t.IsInteger():
  4249  		switch t.Size() {
  4250  		case 1:
  4251  			return s.constInt8(t, 0)
  4252  		case 2:
  4253  			return s.constInt16(t, 0)
  4254  		case 4:
  4255  			return s.constInt32(t, 0)
  4256  		case 8:
  4257  			return s.constInt64(t, 0)
  4258  		default:
  4259  			s.Fatalf("bad sized integer type %v", t)
  4260  		}
  4261  	case t.IsFloat():
  4262  		switch t.Size() {
  4263  		case 4:
  4264  			return s.constFloat32(t, 0)
  4265  		case 8:
  4266  			return s.constFloat64(t, 0)
  4267  		default:
  4268  			s.Fatalf("bad sized float type %v", t)
  4269  		}
  4270  	case t.IsComplex():
  4271  		switch t.Size() {
  4272  		case 8:
  4273  			z := s.constFloat32(types.Types[types.TFLOAT32], 0)
  4274  			return s.entryNewValue2(ssa.OpComplexMake, t, z, z)
  4275  		case 16:
  4276  			z := s.constFloat64(types.Types[types.TFLOAT64], 0)
  4277  			return s.entryNewValue2(ssa.OpComplexMake, t, z, z)
  4278  		default:
  4279  			s.Fatalf("bad sized complex type %v", t)
  4280  		}
  4281  
  4282  	case t.IsString():
  4283  		return s.constEmptyString(t)
  4284  	case t.IsPtrShaped():
  4285  		return s.constNil(t)
  4286  	case t.IsBoolean():
  4287  		return s.constBool(false)
  4288  	case t.IsInterface():
  4289  		return s.constInterface(t)
  4290  	case t.IsSlice():
  4291  		return s.constSlice(t)
  4292  	case t.IsStruct():
  4293  		n := t.NumFields()
  4294  		v := s.entryNewValue0(ssa.OpStructMake, t)
  4295  		for i := 0; i < n; i++ {
  4296  			v.AddArg(s.zeroVal(t.FieldType(i)))
  4297  		}
  4298  		return v
  4299  	case t.IsArray():
  4300  		switch t.NumElem() {
  4301  		case 0:
  4302  			return s.entryNewValue0(ssa.OpArrayMake0, t)
  4303  		case 1:
  4304  			return s.entryNewValue1(ssa.OpArrayMake1, t, s.zeroVal(t.Elem()))
  4305  		}
  4306  	}
  4307  	s.Fatalf("zero for type %v not implemented", t)
  4308  	return nil
  4309  }
  4310  
  4311  type callKind int8
  4312  
  4313  const (
  4314  	callNormal callKind = iota
  4315  	callDefer
  4316  	callDeferStack
  4317  	callGo
  4318  	callTail
  4319  )
  4320  
  4321  type sfRtCallDef struct {
  4322  	rtfn  *obj.LSym
  4323  	rtype types.Kind
  4324  }
  4325  
  4326  var softFloatOps map[ssa.Op]sfRtCallDef
  4327  
  4328  func softfloatInit() {
  4329  	// Some of these operations get transformed by sfcall.
  4330  	softFloatOps = map[ssa.Op]sfRtCallDef{
  4331  		ssa.OpAdd32F: {typecheck.LookupRuntimeFunc("fadd32"), types.TFLOAT32},
  4332  		ssa.OpAdd64F: {typecheck.LookupRuntimeFunc("fadd64"), types.TFLOAT64},
  4333  		ssa.OpSub32F: {typecheck.LookupRuntimeFunc("fadd32"), types.TFLOAT32},
  4334  		ssa.OpSub64F: {typecheck.LookupRuntimeFunc("fadd64"), types.TFLOAT64},
  4335  		ssa.OpMul32F: {typecheck.LookupRuntimeFunc("fmul32"), types.TFLOAT32},
  4336  		ssa.OpMul64F: {typecheck.LookupRuntimeFunc("fmul64"), types.TFLOAT64},
  4337  		ssa.OpDiv32F: {typecheck.LookupRuntimeFunc("fdiv32"), types.TFLOAT32},
  4338  		ssa.OpDiv64F: {typecheck.LookupRuntimeFunc("fdiv64"), types.TFLOAT64},
  4339  
  4340  		ssa.OpEq64F:   {typecheck.LookupRuntimeFunc("feq64"), types.TBOOL},
  4341  		ssa.OpEq32F:   {typecheck.LookupRuntimeFunc("feq32"), types.TBOOL},
  4342  		ssa.OpNeq64F:  {typecheck.LookupRuntimeFunc("feq64"), types.TBOOL},
  4343  		ssa.OpNeq32F:  {typecheck.LookupRuntimeFunc("feq32"), types.TBOOL},
  4344  		ssa.OpLess64F: {typecheck.LookupRuntimeFunc("fgt64"), types.TBOOL},
  4345  		ssa.OpLess32F: {typecheck.LookupRuntimeFunc("fgt32"), types.TBOOL},
  4346  		ssa.OpLeq64F:  {typecheck.LookupRuntimeFunc("fge64"), types.TBOOL},
  4347  		ssa.OpLeq32F:  {typecheck.LookupRuntimeFunc("fge32"), types.TBOOL},
  4348  
  4349  		ssa.OpCvt32to32F:  {typecheck.LookupRuntimeFunc("fint32to32"), types.TFLOAT32},
  4350  		ssa.OpCvt32Fto32:  {typecheck.LookupRuntimeFunc("f32toint32"), types.TINT32},
  4351  		ssa.OpCvt64to32F:  {typecheck.LookupRuntimeFunc("fint64to32"), types.TFLOAT32},
  4352  		ssa.OpCvt32Fto64:  {typecheck.LookupRuntimeFunc("f32toint64"), types.TINT64},
  4353  		ssa.OpCvt64Uto32F: {typecheck.LookupRuntimeFunc("fuint64to32"), types.TFLOAT32},
  4354  		ssa.OpCvt32Fto64U: {typecheck.LookupRuntimeFunc("f32touint64"), types.TUINT64},
  4355  		ssa.OpCvt32to64F:  {typecheck.LookupRuntimeFunc("fint32to64"), types.TFLOAT64},
  4356  		ssa.OpCvt64Fto32:  {typecheck.LookupRuntimeFunc("f64toint32"), types.TINT32},
  4357  		ssa.OpCvt64to64F:  {typecheck.LookupRuntimeFunc("fint64to64"), types.TFLOAT64},
  4358  		ssa.OpCvt64Fto64:  {typecheck.LookupRuntimeFunc("f64toint64"), types.TINT64},
  4359  		ssa.OpCvt64Uto64F: {typecheck.LookupRuntimeFunc("fuint64to64"), types.TFLOAT64},
  4360  		ssa.OpCvt64Fto64U: {typecheck.LookupRuntimeFunc("f64touint64"), types.TUINT64},
  4361  		ssa.OpCvt32Fto64F: {typecheck.LookupRuntimeFunc("f32to64"), types.TFLOAT64},
  4362  		ssa.OpCvt64Fto32F: {typecheck.LookupRuntimeFunc("f64to32"), types.TFLOAT32},
  4363  	}
  4364  }
  4365  
  4366  // TODO: do not emit sfcall if operation can be optimized to constant in later
  4367  // opt phase
  4368  func (s *state) sfcall(op ssa.Op, args ...*ssa.Value) (*ssa.Value, bool) {
  4369  	f2i := func(t *types.Type) *types.Type {
  4370  		switch t.Kind() {
  4371  		case types.TFLOAT32:
  4372  			return types.Types[types.TUINT32]
  4373  		case types.TFLOAT64:
  4374  			return types.Types[types.TUINT64]
  4375  		}
  4376  		return t
  4377  	}
  4378  
  4379  	if callDef, ok := softFloatOps[op]; ok {
  4380  		switch op {
  4381  		case ssa.OpLess32F,
  4382  			ssa.OpLess64F,
  4383  			ssa.OpLeq32F,
  4384  			ssa.OpLeq64F:
  4385  			args[0], args[1] = args[1], args[0]
  4386  		case ssa.OpSub32F,
  4387  			ssa.OpSub64F:
  4388  			args[1] = s.newValue1(s.ssaOp(ir.ONEG, types.Types[callDef.rtype]), args[1].Type, args[1])
  4389  		}
  4390  
  4391  		// runtime functions take uints for floats and returns uints.
  4392  		// Convert to uints so we use the right calling convention.
  4393  		for i, a := range args {
  4394  			if a.Type.IsFloat() {
  4395  				args[i] = s.newValue1(ssa.OpCopy, f2i(a.Type), a)
  4396  			}
  4397  		}
  4398  
  4399  		rt := types.Types[callDef.rtype]
  4400  		result := s.rtcall(callDef.rtfn, true, []*types.Type{f2i(rt)}, args...)[0]
  4401  		if rt.IsFloat() {
  4402  			result = s.newValue1(ssa.OpCopy, rt, result)
  4403  		}
  4404  		if op == ssa.OpNeq32F || op == ssa.OpNeq64F {
  4405  			result = s.newValue1(ssa.OpNot, result.Type, result)
  4406  		}
  4407  		return result, true
  4408  	}
  4409  	return nil, false
  4410  }
  4411  
  4412  // split breaks up a tuple-typed value into its 2 parts.
  4413  func (s *state) split(v *ssa.Value) (*ssa.Value, *ssa.Value) {
  4414  	p0 := s.newValue1(ssa.OpSelect0, v.Type.FieldType(0), v)
  4415  	p1 := s.newValue1(ssa.OpSelect1, v.Type.FieldType(1), v)
  4416  	return p0, p1
  4417  }
  4418  
  4419  // intrinsicCall converts a call to a recognized intrinsic function into the intrinsic SSA operation.
  4420  func (s *state) intrinsicCall(n *ir.CallExpr) *ssa.Value {
  4421  	v := findIntrinsic(n.Fun.Sym())(s, n, s.intrinsicArgs(n))
  4422  	if ssa.IntrinsicsDebug > 0 {
  4423  		x := v
  4424  		if x == nil {
  4425  			x = s.mem()
  4426  		}
  4427  		if x.Op == ssa.OpSelect0 || x.Op == ssa.OpSelect1 {
  4428  			x = x.Args[0]
  4429  		}
  4430  		base.WarnfAt(n.Pos(), "intrinsic substitution for %v with %s", n.Fun.Sym().Name, x.LongString())
  4431  	}
  4432  	return v
  4433  }
  4434  
  4435  // intrinsicArgs extracts args from n, evaluates them to SSA values, and returns them.
  4436  func (s *state) intrinsicArgs(n *ir.CallExpr) []*ssa.Value {
  4437  	args := make([]*ssa.Value, len(n.Args))
  4438  	for i, n := range n.Args {
  4439  		args[i] = s.expr(n)
  4440  	}
  4441  	return args
  4442  }
  4443  
  4444  // openDeferRecord adds code to evaluate and store the function for an open-code defer
  4445  // call, and records info about the defer, so we can generate proper code on the
  4446  // exit paths. n is the sub-node of the defer node that is the actual function
  4447  // call. We will also record funcdata information on where the function is stored
  4448  // (as well as the deferBits variable), and this will enable us to run the proper
  4449  // defer calls during panics.
  4450  func (s *state) openDeferRecord(n *ir.CallExpr) {
  4451  	if len(n.Args) != 0 || n.Op() != ir.OCALLFUNC || n.Fun.Type().NumResults() != 0 {
  4452  		s.Fatalf("defer call with arguments or results: %v", n)
  4453  	}
  4454  
  4455  	opendefer := &openDeferInfo{
  4456  		n: n,
  4457  	}
  4458  	fn := n.Fun
  4459  	// We must always store the function value in a stack slot for the
  4460  	// runtime panic code to use. But in the defer exit code, we will
  4461  	// call the function directly if it is a static function.
  4462  	closureVal := s.expr(fn)
  4463  	closure := s.openDeferSave(fn.Type(), closureVal)
  4464  	opendefer.closureNode = closure.Aux.(*ir.Name)
  4465  	if !(fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC) {
  4466  		opendefer.closure = closure
  4467  	}
  4468  	index := len(s.openDefers)
  4469  	s.openDefers = append(s.openDefers, opendefer)
  4470  
  4471  	// Update deferBits only after evaluation and storage to stack of
  4472  	// the function is successful.
  4473  	bitvalue := s.constInt8(types.Types[types.TUINT8], 1<<uint(index))
  4474  	newDeferBits := s.newValue2(ssa.OpOr8, types.Types[types.TUINT8], s.variable(deferBitsVar, types.Types[types.TUINT8]), bitvalue)
  4475  	s.vars[deferBitsVar] = newDeferBits
  4476  	s.store(types.Types[types.TUINT8], s.deferBitsAddr, newDeferBits)
  4477  }
  4478  
  4479  // openDeferSave generates SSA nodes to store a value (with type t) for an
  4480  // open-coded defer at an explicit autotmp location on the stack, so it can be
  4481  // reloaded and used for the appropriate call on exit. Type t must be a function type
  4482  // (therefore SSAable). val is the value to be stored. The function returns an SSA
  4483  // value representing a pointer to the autotmp location.
  4484  func (s *state) openDeferSave(t *types.Type, val *ssa.Value) *ssa.Value {
  4485  	if !ssa.CanSSA(t) {
  4486  		s.Fatalf("openDeferSave of non-SSA-able type %v val=%v", t, val)
  4487  	}
  4488  	if !t.HasPointers() {
  4489  		s.Fatalf("openDeferSave of pointerless type %v val=%v", t, val)
  4490  	}
  4491  	pos := val.Pos
  4492  	temp := typecheck.TempAt(pos.WithNotStmt(), s.curfn, t)
  4493  	temp.SetOpenDeferSlot(true)
  4494  	temp.SetFrameOffset(int64(len(s.openDefers))) // so cmpstackvarlt can order them
  4495  	var addrTemp *ssa.Value
  4496  	// Use OpVarLive to make sure stack slot for the closure is not removed by
  4497  	// dead-store elimination
  4498  	if s.curBlock.ID != s.f.Entry.ID {
  4499  		// Force the tmp storing this defer function to be declared in the entry
  4500  		// block, so that it will be live for the defer exit code (which will
  4501  		// actually access it only if the associated defer call has been activated).
  4502  		if t.HasPointers() {
  4503  			s.defvars[s.f.Entry.ID][memVar] = s.f.Entry.NewValue1A(src.NoXPos, ssa.OpVarDef, types.TypeMem, temp, s.defvars[s.f.Entry.ID][memVar])
  4504  		}
  4505  		s.defvars[s.f.Entry.ID][memVar] = s.f.Entry.NewValue1A(src.NoXPos, ssa.OpVarLive, types.TypeMem, temp, s.defvars[s.f.Entry.ID][memVar])
  4506  		addrTemp = s.f.Entry.NewValue2A(src.NoXPos, ssa.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.defvars[s.f.Entry.ID][memVar])
  4507  	} else {
  4508  		// Special case if we're still in the entry block. We can't use
  4509  		// the above code, since s.defvars[s.f.Entry.ID] isn't defined
  4510  		// until we end the entry block with s.endBlock().
  4511  		if t.HasPointers() {
  4512  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, temp, s.mem(), false)
  4513  		}
  4514  		s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, temp, s.mem(), false)
  4515  		addrTemp = s.newValue2Apos(ssa.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.mem(), false)
  4516  	}
  4517  	// Since we may use this temp during exit depending on the
  4518  	// deferBits, we must define it unconditionally on entry.
  4519  	// Therefore, we must make sure it is zeroed out in the entry
  4520  	// block if it contains pointers, else GC may wrongly follow an
  4521  	// uninitialized pointer value.
  4522  	temp.SetNeedzero(true)
  4523  	// We are storing to the stack, hence we can avoid the full checks in
  4524  	// storeType() (no write barrier) and do a simple store().
  4525  	s.store(t, addrTemp, val)
  4526  	return addrTemp
  4527  }
  4528  
  4529  // openDeferExit generates SSA for processing all the open coded defers at exit.
  4530  // The code involves loading deferBits, and checking each of the bits to see if
  4531  // the corresponding defer statement was executed. For each bit that is turned
  4532  // on, the associated defer call is made.
  4533  func (s *state) openDeferExit() {
  4534  	deferExit := s.f.NewBlock(ssa.BlockPlain)
  4535  	s.endBlock().AddEdgeTo(deferExit)
  4536  	s.startBlock(deferExit)
  4537  	s.lastDeferExit = deferExit
  4538  	s.lastDeferCount = len(s.openDefers)
  4539  	zeroval := s.constInt8(types.Types[types.TUINT8], 0)
  4540  	// Test for and run defers in reverse order
  4541  	for i := len(s.openDefers) - 1; i >= 0; i-- {
  4542  		r := s.openDefers[i]
  4543  		bCond := s.f.NewBlock(ssa.BlockPlain)
  4544  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  4545  
  4546  		deferBits := s.variable(deferBitsVar, types.Types[types.TUINT8])
  4547  		// Generate code to check if the bit associated with the current
  4548  		// defer is set.
  4549  		bitval := s.constInt8(types.Types[types.TUINT8], 1<<uint(i))
  4550  		andval := s.newValue2(ssa.OpAnd8, types.Types[types.TUINT8], deferBits, bitval)
  4551  		eqVal := s.newValue2(ssa.OpEq8, types.Types[types.TBOOL], andval, zeroval)
  4552  		b := s.endBlock()
  4553  		b.Kind = ssa.BlockIf
  4554  		b.SetControl(eqVal)
  4555  		b.AddEdgeTo(bEnd)
  4556  		b.AddEdgeTo(bCond)
  4557  		bCond.AddEdgeTo(bEnd)
  4558  		s.startBlock(bCond)
  4559  
  4560  		// Clear this bit in deferBits and force store back to stack, so
  4561  		// we will not try to re-run this defer call if this defer call panics.
  4562  		nbitval := s.newValue1(ssa.OpCom8, types.Types[types.TUINT8], bitval)
  4563  		maskedval := s.newValue2(ssa.OpAnd8, types.Types[types.TUINT8], deferBits, nbitval)
  4564  		s.store(types.Types[types.TUINT8], s.deferBitsAddr, maskedval)
  4565  		// Use this value for following tests, so we keep previous
  4566  		// bits cleared.
  4567  		s.vars[deferBitsVar] = maskedval
  4568  
  4569  		// Generate code to call the function call of the defer, using the
  4570  		// closure that were stored in argtmps at the point of the defer
  4571  		// statement.
  4572  		fn := r.n.Fun
  4573  		stksize := fn.Type().ArgWidth()
  4574  		var callArgs []*ssa.Value
  4575  		var call *ssa.Value
  4576  		if r.closure != nil {
  4577  			v := s.load(r.closure.Type.Elem(), r.closure)
  4578  			s.maybeNilCheckClosure(v, callDefer)
  4579  			codeptr := s.rawLoad(types.Types[types.TUINTPTR], v)
  4580  			aux := ssa.ClosureAuxCall(s.f.ABIDefault.ABIAnalyzeTypes(nil, nil))
  4581  			call = s.newValue2A(ssa.OpClosureLECall, aux.LateExpansionResultType(), aux, codeptr, v)
  4582  		} else {
  4583  			aux := ssa.StaticAuxCall(fn.(*ir.Name).Linksym(), s.f.ABIDefault.ABIAnalyzeTypes(nil, nil))
  4584  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4585  		}
  4586  		callArgs = append(callArgs, s.mem())
  4587  		call.AddArgs(callArgs...)
  4588  		call.AuxInt = stksize
  4589  		s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, 0, call)
  4590  		// Make sure that the stack slots with pointers are kept live
  4591  		// through the call (which is a pre-emption point). Also, we will
  4592  		// use the first call of the last defer exit to compute liveness
  4593  		// for the deferreturn, so we want all stack slots to be live.
  4594  		if r.closureNode != nil {
  4595  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, r.closureNode, s.mem(), false)
  4596  		}
  4597  
  4598  		s.endBlock()
  4599  		s.startBlock(bEnd)
  4600  	}
  4601  }
  4602  
  4603  func (s *state) callResult(n *ir.CallExpr, k callKind) *ssa.Value {
  4604  	return s.call(n, k, false, nil)
  4605  }
  4606  
  4607  func (s *state) callAddr(n *ir.CallExpr, k callKind) *ssa.Value {
  4608  	return s.call(n, k, true, nil)
  4609  }
  4610  
  4611  // Calls the function n using the specified call type.
  4612  // Returns the address of the return value (or nil if none).
  4613  func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool, deferExtra ir.Expr) *ssa.Value {
  4614  	s.prevCall = nil
  4615  	var calleeLSym *obj.LSym // target function (if static)
  4616  	var closure *ssa.Value   // ptr to closure to run (if dynamic)
  4617  	var codeptr *ssa.Value   // ptr to target code (if dynamic)
  4618  	var dextra *ssa.Value    // defer extra arg
  4619  	var rcvr *ssa.Value      // receiver to set
  4620  	fn := n.Fun
  4621  	var ACArgs []*types.Type    // AuxCall args
  4622  	var ACResults []*types.Type // AuxCall results
  4623  	var callArgs []*ssa.Value   // For late-expansion, the args themselves (not stored, args to the call instead).
  4624  
  4625  	callABI := s.f.ABIDefault
  4626  
  4627  	if k != callNormal && k != callTail && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.Fun.Type().NumResults() != 0) {
  4628  		s.Fatalf("go/defer call with arguments: %v", n)
  4629  	}
  4630  
  4631  	isCallDeferRangeFunc := false
  4632  
  4633  	switch n.Op() {
  4634  	case ir.OCALLFUNC:
  4635  		if (k == callNormal || k == callTail) && fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC {
  4636  			fn := fn.(*ir.Name)
  4637  			calleeLSym = callTargetLSym(fn)
  4638  			if buildcfg.Experiment.RegabiArgs {
  4639  				// This is a static call, so it may be
  4640  				// a direct call to a non-ABIInternal
  4641  				// function. fn.Func may be nil for
  4642  				// some compiler-generated functions,
  4643  				// but those are all ABIInternal.
  4644  				if fn.Func != nil {
  4645  					callABI = abiForFunc(fn.Func, s.f.ABI0, s.f.ABI1)
  4646  				}
  4647  			} else {
  4648  				// TODO(register args) remove after register abi is working
  4649  				inRegistersImported := fn.Pragma()&ir.RegisterParams != 0
  4650  				inRegistersSamePackage := fn.Func != nil && fn.Func.Pragma&ir.RegisterParams != 0
  4651  				if inRegistersImported || inRegistersSamePackage {
  4652  					callABI = s.f.ABI1
  4653  				}
  4654  			}
  4655  			if fn := n.Fun.Sym().Name; n.Fun.Sym().Pkg == ir.Pkgs.Runtime && fn == "deferrangefunc" {
  4656  				isCallDeferRangeFunc = true
  4657  			}
  4658  			break
  4659  		}
  4660  		closure = s.expr(fn)
  4661  		if k != callDefer && k != callDeferStack {
  4662  			// Deferred nil function needs to panic when the function is invoked,
  4663  			// not the point of defer statement.
  4664  			s.maybeNilCheckClosure(closure, k)
  4665  		}
  4666  	case ir.OCALLINTER:
  4667  		if fn.Op() != ir.ODOTINTER {
  4668  			s.Fatalf("OCALLINTER: n.Left not an ODOTINTER: %v", fn.Op())
  4669  		}
  4670  		fn := fn.(*ir.SelectorExpr)
  4671  		var iclosure *ssa.Value
  4672  		iclosure, rcvr = s.getClosureAndRcvr(fn)
  4673  		if k == callNormal {
  4674  			codeptr = s.load(types.Types[types.TUINTPTR], iclosure)
  4675  		} else {
  4676  			closure = iclosure
  4677  		}
  4678  	}
  4679  	if deferExtra != nil {
  4680  		dextra = s.expr(deferExtra)
  4681  	}
  4682  
  4683  	params := callABI.ABIAnalyze(n.Fun.Type(), false /* Do not set (register) nNames from caller side -- can cause races. */)
  4684  	types.CalcSize(fn.Type())
  4685  	stksize := params.ArgWidth() // includes receiver, args, and results
  4686  
  4687  	res := n.Fun.Type().Results()
  4688  	if k == callNormal || k == callTail {
  4689  		for _, p := range params.OutParams() {
  4690  			ACResults = append(ACResults, p.Type)
  4691  		}
  4692  	}
  4693  
  4694  	var call *ssa.Value
  4695  	if k == callDeferStack {
  4696  		if stksize != 0 {
  4697  			s.Fatalf("deferprocStack with non-zero stack size %d: %v", stksize, n)
  4698  		}
  4699  		// Make a defer struct on the stack.
  4700  		t := deferstruct()
  4701  		n, addr := s.temp(n.Pos(), t)
  4702  		n.SetNonMergeable(true)
  4703  		s.store(closure.Type,
  4704  			s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(deferStructFnField), addr),
  4705  			closure)
  4706  
  4707  		// Call runtime.deferprocStack with pointer to _defer record.
  4708  		ACArgs = append(ACArgs, types.Types[types.TUINTPTR])
  4709  		aux := ssa.StaticAuxCall(ir.Syms.DeferprocStack, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults))
  4710  		callArgs = append(callArgs, addr, s.mem())
  4711  		call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4712  		call.AddArgs(callArgs...)
  4713  		call.AuxInt = int64(types.PtrSize) // deferprocStack takes a *_defer arg
  4714  	} else {
  4715  		// Store arguments to stack, including defer/go arguments and receiver for method calls.
  4716  		// These are written in SP-offset order.
  4717  		argStart := base.Ctxt.Arch.FixedFrameSize
  4718  		// Defer/go args.
  4719  		if k != callNormal && k != callTail {
  4720  			// Write closure (arg to newproc/deferproc).
  4721  			ACArgs = append(ACArgs, types.Types[types.TUINTPTR]) // not argExtra
  4722  			callArgs = append(callArgs, closure)
  4723  			stksize += int64(types.PtrSize)
  4724  			argStart += int64(types.PtrSize)
  4725  			if dextra != nil {
  4726  				// Extra token of type any for deferproc
  4727  				ACArgs = append(ACArgs, types.Types[types.TINTER])
  4728  				callArgs = append(callArgs, dextra)
  4729  				stksize += 2 * int64(types.PtrSize)
  4730  				argStart += 2 * int64(types.PtrSize)
  4731  			}
  4732  		}
  4733  
  4734  		// Set receiver (for interface calls).
  4735  		if rcvr != nil {
  4736  			callArgs = append(callArgs, rcvr)
  4737  		}
  4738  
  4739  		// Write args.
  4740  		t := n.Fun.Type()
  4741  		args := n.Args
  4742  
  4743  		for _, p := range params.InParams() { // includes receiver for interface calls
  4744  			ACArgs = append(ACArgs, p.Type)
  4745  		}
  4746  
  4747  		// Split the entry block if there are open defers, because later calls to
  4748  		// openDeferSave may cause a mismatch between the mem for an OpDereference
  4749  		// and the call site which uses it. See #49282.
  4750  		if s.curBlock.ID == s.f.Entry.ID && s.hasOpenDefers {
  4751  			b := s.endBlock()
  4752  			b.Kind = ssa.BlockPlain
  4753  			curb := s.f.NewBlock(ssa.BlockPlain)
  4754  			b.AddEdgeTo(curb)
  4755  			s.startBlock(curb)
  4756  		}
  4757  
  4758  		for i, n := range args {
  4759  			callArgs = append(callArgs, s.putArg(n, t.Param(i).Type))
  4760  		}
  4761  
  4762  		callArgs = append(callArgs, s.mem())
  4763  
  4764  		// call target
  4765  		switch {
  4766  		case k == callDefer:
  4767  			sym := ir.Syms.Deferproc
  4768  			if dextra != nil {
  4769  				sym = ir.Syms.Deferprocat
  4770  			}
  4771  			aux := ssa.StaticAuxCall(sym, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults)) // TODO paramResultInfo for Deferproc(at)
  4772  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4773  		case k == callGo:
  4774  			aux := ssa.StaticAuxCall(ir.Syms.Newproc, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults))
  4775  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux) // TODO paramResultInfo for Newproc
  4776  		case closure != nil:
  4777  			// rawLoad because loading the code pointer from a
  4778  			// closure is always safe, but IsSanitizerSafeAddr
  4779  			// can't always figure that out currently, and it's
  4780  			// critical that we not clobber any arguments already
  4781  			// stored onto the stack.
  4782  			codeptr = s.rawLoad(types.Types[types.TUINTPTR], closure)
  4783  			aux := ssa.ClosureAuxCall(callABI.ABIAnalyzeTypes(ACArgs, ACResults))
  4784  			call = s.newValue2A(ssa.OpClosureLECall, aux.LateExpansionResultType(), aux, codeptr, closure)
  4785  		case codeptr != nil:
  4786  			// Note that the "receiver" parameter is nil because the actual receiver is the first input parameter.
  4787  			aux := ssa.InterfaceAuxCall(params)
  4788  			call = s.newValue1A(ssa.OpInterLECall, aux.LateExpansionResultType(), aux, codeptr)
  4789  		case calleeLSym != nil:
  4790  			aux := ssa.StaticAuxCall(calleeLSym, params)
  4791  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4792  			if k == callTail {
  4793  				call.Op = ssa.OpTailLECall
  4794  				stksize = 0 // Tail call does not use stack. We reuse caller's frame.
  4795  			}
  4796  		default:
  4797  			s.Fatalf("bad call type %v %v", n.Op(), n)
  4798  		}
  4799  		call.AddArgs(callArgs...)
  4800  		call.AuxInt = stksize // Call operations carry the argsize of the callee along with them
  4801  	}
  4802  	s.prevCall = call
  4803  	s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, int64(len(ACResults)), call)
  4804  	// Insert VarLive opcodes.
  4805  	for _, v := range n.KeepAlive {
  4806  		if !v.Addrtaken() {
  4807  			s.Fatalf("KeepAlive variable %v must have Addrtaken set", v)
  4808  		}
  4809  		switch v.Class {
  4810  		case ir.PAUTO, ir.PPARAM, ir.PPARAMOUT:
  4811  		default:
  4812  			s.Fatalf("KeepAlive variable %v must be Auto or Arg", v)
  4813  		}
  4814  		s.vars[memVar] = s.newValue1A(ssa.OpVarLive, types.TypeMem, v, s.mem())
  4815  	}
  4816  
  4817  	// Finish block for defers
  4818  	if k == callDefer || k == callDeferStack || isCallDeferRangeFunc {
  4819  		b := s.endBlock()
  4820  		b.Kind = ssa.BlockDefer
  4821  		b.SetControl(call)
  4822  		bNext := s.f.NewBlock(ssa.BlockPlain)
  4823  		b.AddEdgeTo(bNext)
  4824  		r := s.f.DeferReturn // Share a single deferreturn among all defers
  4825  		if r == nil {
  4826  			r = s.f.NewBlock(ssa.BlockPlain)
  4827  			s.startBlock(r)
  4828  			s.exit()
  4829  			s.f.DeferReturn = r
  4830  		}
  4831  		b.AddEdgeTo(r) // Add recover edge to exit code.  This is a fake edge to keep the block live.
  4832  		b.Likely = ssa.BranchLikely
  4833  		s.startBlock(bNext)
  4834  	}
  4835  
  4836  	if len(res) == 0 || k != callNormal {
  4837  		// call has no return value. Continue with the next statement.
  4838  		return nil
  4839  	}
  4840  	fp := res[0]
  4841  	if returnResultAddr {
  4842  		return s.resultAddrOfCall(call, 0, fp.Type)
  4843  	}
  4844  	return s.newValue1I(ssa.OpSelectN, fp.Type, 0, call)
  4845  }
  4846  
  4847  // maybeNilCheckClosure checks if a nil check of a closure is needed in some
  4848  // architecture-dependent situations and, if so, emits the nil check.
  4849  func (s *state) maybeNilCheckClosure(closure *ssa.Value, k callKind) {
  4850  	if Arch.LinkArch.Family == sys.Wasm || buildcfg.GOOS == "aix" && k != callGo {
  4851  		// 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.
  4852  		// TODO(neelance): On other architectures this should be eliminated by the optimization steps
  4853  		s.nilCheck(closure)
  4854  	}
  4855  }
  4856  
  4857  // getClosureAndRcvr returns values for the appropriate closure and receiver of an
  4858  // interface call
  4859  func (s *state) getClosureAndRcvr(fn *ir.SelectorExpr) (*ssa.Value, *ssa.Value) {
  4860  	i := s.expr(fn.X)
  4861  	itab := s.newValue1(ssa.OpITab, types.Types[types.TUINTPTR], i)
  4862  	s.nilCheck(itab)
  4863  	itabidx := fn.Offset() + rttype.ITab.OffsetOf("Fun")
  4864  	closure := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.UintptrPtr, itabidx, itab)
  4865  	rcvr := s.newValue1(ssa.OpIData, s.f.Config.Types.BytePtr, i)
  4866  	return closure, rcvr
  4867  }
  4868  
  4869  // etypesign returns the signed-ness of e, for integer/pointer etypes.
  4870  // -1 means signed, +1 means unsigned, 0 means non-integer/non-pointer.
  4871  func etypesign(e types.Kind) int8 {
  4872  	switch e {
  4873  	case types.TINT8, types.TINT16, types.TINT32, types.TINT64, types.TINT:
  4874  		return -1
  4875  	case types.TUINT8, types.TUINT16, types.TUINT32, types.TUINT64, types.TUINT, types.TUINTPTR, types.TUNSAFEPTR:
  4876  		return +1
  4877  	}
  4878  	return 0
  4879  }
  4880  
  4881  // addr converts the address of the expression n to SSA, adds it to s and returns the SSA result.
  4882  // The value that the returned Value represents is guaranteed to be non-nil.
  4883  func (s *state) addr(n ir.Node) *ssa.Value {
  4884  	if n.Op() != ir.ONAME {
  4885  		s.pushLine(n.Pos())
  4886  		defer s.popLine()
  4887  	}
  4888  
  4889  	if s.canSSA(n) {
  4890  		s.Fatalf("addr of canSSA expression: %+v", n)
  4891  	}
  4892  
  4893  	t := types.NewPtr(n.Type())
  4894  	linksymOffset := func(lsym *obj.LSym, offset int64) *ssa.Value {
  4895  		v := s.entryNewValue1A(ssa.OpAddr, t, lsym, s.sb)
  4896  		// TODO: Make OpAddr use AuxInt as well as Aux.
  4897  		if offset != 0 {
  4898  			v = s.entryNewValue1I(ssa.OpOffPtr, v.Type, offset, v)
  4899  		}
  4900  		return v
  4901  	}
  4902  	switch n.Op() {
  4903  	case ir.OLINKSYMOFFSET:
  4904  		no := n.(*ir.LinksymOffsetExpr)
  4905  		return linksymOffset(no.Linksym, no.Offset_)
  4906  	case ir.ONAME:
  4907  		n := n.(*ir.Name)
  4908  		if n.Heapaddr != nil {
  4909  			return s.expr(n.Heapaddr)
  4910  		}
  4911  		switch n.Class {
  4912  		case ir.PEXTERN:
  4913  			// global variable
  4914  			return linksymOffset(n.Linksym(), 0)
  4915  		case ir.PPARAM:
  4916  			// parameter slot
  4917  			v := s.decladdrs[n]
  4918  			if v != nil {
  4919  				return v
  4920  			}
  4921  			s.Fatalf("addr of undeclared ONAME %v. declared: %v", n, s.decladdrs)
  4922  			return nil
  4923  		case ir.PAUTO:
  4924  			return s.newValue2Apos(ssa.OpLocalAddr, t, n, s.sp, s.mem(), !ir.IsAutoTmp(n))
  4925  
  4926  		case ir.PPARAMOUT: // Same as PAUTO -- cannot generate LEA early.
  4927  			// ensure that we reuse symbols for out parameters so
  4928  			// that cse works on their addresses
  4929  			return s.newValue2Apos(ssa.OpLocalAddr, t, n, s.sp, s.mem(), true)
  4930  		default:
  4931  			s.Fatalf("variable address class %v not implemented", n.Class)
  4932  			return nil
  4933  		}
  4934  	case ir.ORESULT:
  4935  		// load return from callee
  4936  		n := n.(*ir.ResultExpr)
  4937  		return s.resultAddrOfCall(s.prevCall, n.Index, n.Type())
  4938  	case ir.OINDEX:
  4939  		n := n.(*ir.IndexExpr)
  4940  		if n.X.Type().IsSlice() {
  4941  			a := s.expr(n.X)
  4942  			i := s.expr(n.Index)
  4943  			len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], a)
  4944  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  4945  			p := s.newValue1(ssa.OpSlicePtr, t, a)
  4946  			return s.newValue2(ssa.OpPtrIndex, t, p, i)
  4947  		} else { // array
  4948  			a := s.addr(n.X)
  4949  			i := s.expr(n.Index)
  4950  			len := s.constInt(types.Types[types.TINT], n.X.Type().NumElem())
  4951  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  4952  			return s.newValue2(ssa.OpPtrIndex, types.NewPtr(n.X.Type().Elem()), a, i)
  4953  		}
  4954  	case ir.ODEREF:
  4955  		n := n.(*ir.StarExpr)
  4956  		return s.exprPtr(n.X, n.Bounded(), n.Pos())
  4957  	case ir.ODOT:
  4958  		n := n.(*ir.SelectorExpr)
  4959  		p := s.addr(n.X)
  4960  		return s.newValue1I(ssa.OpOffPtr, t, n.Offset(), p)
  4961  	case ir.ODOTPTR:
  4962  		n := n.(*ir.SelectorExpr)
  4963  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  4964  		return s.newValue1I(ssa.OpOffPtr, t, n.Offset(), p)
  4965  	case ir.OCONVNOP:
  4966  		n := n.(*ir.ConvExpr)
  4967  		if n.Type() == n.X.Type() {
  4968  			return s.addr(n.X)
  4969  		}
  4970  		addr := s.addr(n.X)
  4971  		return s.newValue1(ssa.OpCopy, t, addr) // ensure that addr has the right type
  4972  	case ir.OCALLFUNC, ir.OCALLINTER:
  4973  		n := n.(*ir.CallExpr)
  4974  		return s.callAddr(n, callNormal)
  4975  	case ir.ODOTTYPE, ir.ODYNAMICDOTTYPE:
  4976  		var v *ssa.Value
  4977  		if n.Op() == ir.ODOTTYPE {
  4978  			v, _ = s.dottype(n.(*ir.TypeAssertExpr), false)
  4979  		} else {
  4980  			v, _ = s.dynamicDottype(n.(*ir.DynamicTypeAssertExpr), false)
  4981  		}
  4982  		if v.Op != ssa.OpLoad {
  4983  			s.Fatalf("dottype of non-load")
  4984  		}
  4985  		if v.Args[1] != s.mem() {
  4986  			s.Fatalf("memory no longer live from dottype load")
  4987  		}
  4988  		return v.Args[0]
  4989  	default:
  4990  		s.Fatalf("unhandled addr %v", n.Op())
  4991  		return nil
  4992  	}
  4993  }
  4994  
  4995  // canSSA reports whether n is SSA-able.
  4996  // n must be an ONAME (or an ODOT sequence with an ONAME base).
  4997  func (s *state) canSSA(n ir.Node) bool {
  4998  	if base.Flag.N != 0 {
  4999  		return false
  5000  	}
  5001  	for {
  5002  		nn := n
  5003  		if nn.Op() == ir.ODOT {
  5004  			nn := nn.(*ir.SelectorExpr)
  5005  			n = nn.X
  5006  			continue
  5007  		}
  5008  		if nn.Op() == ir.OINDEX {
  5009  			nn := nn.(*ir.IndexExpr)
  5010  			if nn.X.Type().IsArray() {
  5011  				n = nn.X
  5012  				continue
  5013  			}
  5014  		}
  5015  		break
  5016  	}
  5017  	if n.Op() != ir.ONAME {
  5018  		return false
  5019  	}
  5020  	return s.canSSAName(n.(*ir.Name)) && ssa.CanSSA(n.Type())
  5021  }
  5022  
  5023  func (s *state) canSSAName(name *ir.Name) bool {
  5024  	if name.Addrtaken() || !name.OnStack() {
  5025  		return false
  5026  	}
  5027  	switch name.Class {
  5028  	case ir.PPARAMOUT:
  5029  		if s.hasdefer {
  5030  			// TODO: handle this case? Named return values must be
  5031  			// in memory so that the deferred function can see them.
  5032  			// Maybe do: if !strings.HasPrefix(n.String(), "~") { return false }
  5033  			// Or maybe not, see issue 18860.  Even unnamed return values
  5034  			// must be written back so if a defer recovers, the caller can see them.
  5035  			return false
  5036  		}
  5037  		if s.cgoUnsafeArgs {
  5038  			// Cgo effectively takes the address of all result args,
  5039  			// but the compiler can't see that.
  5040  			return false
  5041  		}
  5042  	}
  5043  	return true
  5044  	// TODO: try to make more variables SSAable?
  5045  }
  5046  
  5047  // exprPtr evaluates n to a pointer and nil-checks it.
  5048  func (s *state) exprPtr(n ir.Node, bounded bool, lineno src.XPos) *ssa.Value {
  5049  	p := s.expr(n)
  5050  	if bounded || n.NonNil() {
  5051  		if s.f.Frontend().Debug_checknil() && lineno.Line() > 1 {
  5052  			s.f.Warnl(lineno, "removed nil check")
  5053  		}
  5054  		return p
  5055  	}
  5056  	p = s.nilCheck(p)
  5057  	return p
  5058  }
  5059  
  5060  // nilCheck generates nil pointer checking code.
  5061  // Used only for automatically inserted nil checks,
  5062  // not for user code like 'x != nil'.
  5063  // Returns a "definitely not nil" copy of x to ensure proper ordering
  5064  // of the uses of the post-nilcheck pointer.
  5065  func (s *state) nilCheck(ptr *ssa.Value) *ssa.Value {
  5066  	if base.Debug.DisableNil != 0 || s.curfn.NilCheckDisabled() {
  5067  		return ptr
  5068  	}
  5069  	return s.newValue2(ssa.OpNilCheck, ptr.Type, ptr, s.mem())
  5070  }
  5071  
  5072  // boundsCheck generates bounds checking code. Checks if 0 <= idx <[=] len, branches to exit if not.
  5073  // Starts a new block on return.
  5074  // On input, len must be converted to full int width and be nonnegative.
  5075  // Returns idx converted to full int width.
  5076  // If bounded is true then caller guarantees the index is not out of bounds
  5077  // (but boundsCheck will still extend the index to full int width).
  5078  func (s *state) boundsCheck(idx, len *ssa.Value, kind ssa.BoundsKind, bounded bool) *ssa.Value {
  5079  	idx = s.extendIndex(idx, len, kind, bounded)
  5080  
  5081  	if bounded || base.Flag.B != 0 {
  5082  		// If bounded or bounds checking is flag-disabled, then no check necessary,
  5083  		// just return the extended index.
  5084  		//
  5085  		// Here, bounded == true if the compiler generated the index itself,
  5086  		// such as in the expansion of a slice initializer. These indexes are
  5087  		// compiler-generated, not Go program variables, so they cannot be
  5088  		// attacker-controlled, so we can omit Spectre masking as well.
  5089  		//
  5090  		// Note that we do not want to omit Spectre masking in code like:
  5091  		//
  5092  		//	if 0 <= i && i < len(x) {
  5093  		//		use(x[i])
  5094  		//	}
  5095  		//
  5096  		// Lucky for us, bounded==false for that code.
  5097  		// In that case (handled below), we emit a bound check (and Spectre mask)
  5098  		// and then the prove pass will remove the bounds check.
  5099  		// In theory the prove pass could potentially remove certain
  5100  		// Spectre masks, but it's very delicate and probably better
  5101  		// to be conservative and leave them all in.
  5102  		return idx
  5103  	}
  5104  
  5105  	bNext := s.f.NewBlock(ssa.BlockPlain)
  5106  	bPanic := s.f.NewBlock(ssa.BlockExit)
  5107  
  5108  	if !idx.Type.IsSigned() {
  5109  		switch kind {
  5110  		case ssa.BoundsIndex:
  5111  			kind = ssa.BoundsIndexU
  5112  		case ssa.BoundsSliceAlen:
  5113  			kind = ssa.BoundsSliceAlenU
  5114  		case ssa.BoundsSliceAcap:
  5115  			kind = ssa.BoundsSliceAcapU
  5116  		case ssa.BoundsSliceB:
  5117  			kind = ssa.BoundsSliceBU
  5118  		case ssa.BoundsSlice3Alen:
  5119  			kind = ssa.BoundsSlice3AlenU
  5120  		case ssa.BoundsSlice3Acap:
  5121  			kind = ssa.BoundsSlice3AcapU
  5122  		case ssa.BoundsSlice3B:
  5123  			kind = ssa.BoundsSlice3BU
  5124  		case ssa.BoundsSlice3C:
  5125  			kind = ssa.BoundsSlice3CU
  5126  		}
  5127  	}
  5128  
  5129  	var cmp *ssa.Value
  5130  	if kind == ssa.BoundsIndex || kind == ssa.BoundsIndexU {
  5131  		cmp = s.newValue2(ssa.OpIsInBounds, types.Types[types.TBOOL], idx, len)
  5132  	} else {
  5133  		cmp = s.newValue2(ssa.OpIsSliceInBounds, types.Types[types.TBOOL], idx, len)
  5134  	}
  5135  	b := s.endBlock()
  5136  	b.Kind = ssa.BlockIf
  5137  	b.SetControl(cmp)
  5138  	b.Likely = ssa.BranchLikely
  5139  	b.AddEdgeTo(bNext)
  5140  	b.AddEdgeTo(bPanic)
  5141  
  5142  	s.startBlock(bPanic)
  5143  	if Arch.LinkArch.Family == sys.Wasm {
  5144  		// TODO(khr): figure out how to do "register" based calling convention for bounds checks.
  5145  		// Should be similar to gcWriteBarrier, but I can't make it work.
  5146  		s.rtcall(BoundsCheckFunc[kind], false, nil, idx, len)
  5147  	} else {
  5148  		mem := s.newValue3I(ssa.OpPanicBounds, types.TypeMem, int64(kind), idx, len, s.mem())
  5149  		s.endBlock().SetControl(mem)
  5150  	}
  5151  	s.startBlock(bNext)
  5152  
  5153  	// In Spectre index mode, apply an appropriate mask to avoid speculative out-of-bounds accesses.
  5154  	if base.Flag.Cfg.SpectreIndex {
  5155  		op := ssa.OpSpectreIndex
  5156  		if kind != ssa.BoundsIndex && kind != ssa.BoundsIndexU {
  5157  			op = ssa.OpSpectreSliceIndex
  5158  		}
  5159  		idx = s.newValue2(op, types.Types[types.TINT], idx, len)
  5160  	}
  5161  
  5162  	return idx
  5163  }
  5164  
  5165  // If cmp (a bool) is false, panic using the given function.
  5166  func (s *state) check(cmp *ssa.Value, fn *obj.LSym) {
  5167  	b := s.endBlock()
  5168  	b.Kind = ssa.BlockIf
  5169  	b.SetControl(cmp)
  5170  	b.Likely = ssa.BranchLikely
  5171  	bNext := s.f.NewBlock(ssa.BlockPlain)
  5172  	line := s.peekPos()
  5173  	pos := base.Ctxt.PosTable.Pos(line)
  5174  	fl := funcLine{f: fn, base: pos.Base(), line: pos.Line()}
  5175  	bPanic := s.panics[fl]
  5176  	if bPanic == nil {
  5177  		bPanic = s.f.NewBlock(ssa.BlockPlain)
  5178  		s.panics[fl] = bPanic
  5179  		s.startBlock(bPanic)
  5180  		// The panic call takes/returns memory to ensure that the right
  5181  		// memory state is observed if the panic happens.
  5182  		s.rtcall(fn, false, nil)
  5183  	}
  5184  	b.AddEdgeTo(bNext)
  5185  	b.AddEdgeTo(bPanic)
  5186  	s.startBlock(bNext)
  5187  }
  5188  
  5189  func (s *state) intDivide(n ir.Node, a, b *ssa.Value) *ssa.Value {
  5190  	needcheck := true
  5191  	switch b.Op {
  5192  	case ssa.OpConst8, ssa.OpConst16, ssa.OpConst32, ssa.OpConst64:
  5193  		if b.AuxInt != 0 {
  5194  			needcheck = false
  5195  		}
  5196  	}
  5197  	if needcheck {
  5198  		// do a size-appropriate check for zero
  5199  		cmp := s.newValue2(s.ssaOp(ir.ONE, n.Type()), types.Types[types.TBOOL], b, s.zeroVal(n.Type()))
  5200  		s.check(cmp, ir.Syms.Panicdivide)
  5201  	}
  5202  	return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  5203  }
  5204  
  5205  // rtcall issues a call to the given runtime function fn with the listed args.
  5206  // Returns a slice of results of the given result types.
  5207  // The call is added to the end of the current block.
  5208  // If returns is false, the block is marked as an exit block.
  5209  func (s *state) rtcall(fn *obj.LSym, returns bool, results []*types.Type, args ...*ssa.Value) []*ssa.Value {
  5210  	s.prevCall = nil
  5211  	// Write args to the stack
  5212  	off := base.Ctxt.Arch.FixedFrameSize
  5213  	var callArgs []*ssa.Value
  5214  	var callArgTypes []*types.Type
  5215  
  5216  	for _, arg := range args {
  5217  		t := arg.Type
  5218  		off = types.RoundUp(off, t.Alignment())
  5219  		size := t.Size()
  5220  		callArgs = append(callArgs, arg)
  5221  		callArgTypes = append(callArgTypes, t)
  5222  		off += size
  5223  	}
  5224  	off = types.RoundUp(off, int64(types.RegSize))
  5225  
  5226  	// Issue call
  5227  	var call *ssa.Value
  5228  	aux := ssa.StaticAuxCall(fn, s.f.ABIDefault.ABIAnalyzeTypes(callArgTypes, results))
  5229  	callArgs = append(callArgs, s.mem())
  5230  	call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  5231  	call.AddArgs(callArgs...)
  5232  	s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, int64(len(results)), call)
  5233  
  5234  	if !returns {
  5235  		// Finish block
  5236  		b := s.endBlock()
  5237  		b.Kind = ssa.BlockExit
  5238  		b.SetControl(call)
  5239  		call.AuxInt = off - base.Ctxt.Arch.FixedFrameSize
  5240  		if len(results) > 0 {
  5241  			s.Fatalf("panic call can't have results")
  5242  		}
  5243  		return nil
  5244  	}
  5245  
  5246  	// Load results
  5247  	res := make([]*ssa.Value, len(results))
  5248  	for i, t := range results {
  5249  		off = types.RoundUp(off, t.Alignment())
  5250  		res[i] = s.resultOfCall(call, int64(i), t)
  5251  		off += t.Size()
  5252  	}
  5253  	off = types.RoundUp(off, int64(types.PtrSize))
  5254  
  5255  	// Remember how much callee stack space we needed.
  5256  	call.AuxInt = off
  5257  
  5258  	return res
  5259  }
  5260  
  5261  // do *left = right for type t.
  5262  func (s *state) storeType(t *types.Type, left, right *ssa.Value, skip skipMask, leftIsStmt bool) {
  5263  	s.instrument(t, left, instrumentWrite)
  5264  
  5265  	if skip == 0 && (!t.HasPointers() || ssa.IsStackAddr(left)) {
  5266  		// Known to not have write barrier. Store the whole type.
  5267  		s.vars[memVar] = s.newValue3Apos(ssa.OpStore, types.TypeMem, t, left, right, s.mem(), leftIsStmt)
  5268  		return
  5269  	}
  5270  
  5271  	// store scalar fields first, so write barrier stores for
  5272  	// pointer fields can be grouped together, and scalar values
  5273  	// don't need to be live across the write barrier call.
  5274  	// TODO: if the writebarrier pass knows how to reorder stores,
  5275  	// we can do a single store here as long as skip==0.
  5276  	s.storeTypeScalars(t, left, right, skip)
  5277  	if skip&skipPtr == 0 && t.HasPointers() {
  5278  		s.storeTypePtrs(t, left, right)
  5279  	}
  5280  }
  5281  
  5282  // do *left = right for all scalar (non-pointer) parts of t.
  5283  func (s *state) storeTypeScalars(t *types.Type, left, right *ssa.Value, skip skipMask) {
  5284  	switch {
  5285  	case t.IsBoolean() || t.IsInteger() || t.IsFloat() || t.IsComplex():
  5286  		s.store(t, left, right)
  5287  	case t.IsPtrShaped():
  5288  		if t.IsPtr() && t.Elem().NotInHeap() {
  5289  			s.store(t, left, right) // see issue 42032
  5290  		}
  5291  		// otherwise, no scalar fields.
  5292  	case t.IsString():
  5293  		if skip&skipLen != 0 {
  5294  			return
  5295  		}
  5296  		len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], right)
  5297  		lenAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, s.config.PtrSize, left)
  5298  		s.store(types.Types[types.TINT], lenAddr, len)
  5299  	case t.IsSlice():
  5300  		if skip&skipLen == 0 {
  5301  			len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], right)
  5302  			lenAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, s.config.PtrSize, left)
  5303  			s.store(types.Types[types.TINT], lenAddr, len)
  5304  		}
  5305  		if skip&skipCap == 0 {
  5306  			cap := s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], right)
  5307  			capAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, 2*s.config.PtrSize, left)
  5308  			s.store(types.Types[types.TINT], capAddr, cap)
  5309  		}
  5310  	case t.IsInterface():
  5311  		// itab field doesn't need a write barrier (even though it is a pointer).
  5312  		itab := s.newValue1(ssa.OpITab, s.f.Config.Types.BytePtr, right)
  5313  		s.store(types.Types[types.TUINTPTR], left, itab)
  5314  	case t.IsStruct():
  5315  		n := t.NumFields()
  5316  		for i := 0; i < n; i++ {
  5317  			ft := t.FieldType(i)
  5318  			addr := s.newValue1I(ssa.OpOffPtr, ft.PtrTo(), t.FieldOff(i), left)
  5319  			val := s.newValue1I(ssa.OpStructSelect, ft, int64(i), right)
  5320  			s.storeTypeScalars(ft, addr, val, 0)
  5321  		}
  5322  	case t.IsArray() && t.NumElem() == 0:
  5323  		// nothing
  5324  	case t.IsArray() && t.NumElem() == 1:
  5325  		s.storeTypeScalars(t.Elem(), left, s.newValue1I(ssa.OpArraySelect, t.Elem(), 0, right), 0)
  5326  	default:
  5327  		s.Fatalf("bad write barrier type %v", t)
  5328  	}
  5329  }
  5330  
  5331  // do *left = right for all pointer parts of t.
  5332  func (s *state) storeTypePtrs(t *types.Type, left, right *ssa.Value) {
  5333  	switch {
  5334  	case t.IsPtrShaped():
  5335  		if t.IsPtr() && t.Elem().NotInHeap() {
  5336  			break // see issue 42032
  5337  		}
  5338  		s.store(t, left, right)
  5339  	case t.IsString():
  5340  		ptr := s.newValue1(ssa.OpStringPtr, s.f.Config.Types.BytePtr, right)
  5341  		s.store(s.f.Config.Types.BytePtr, left, ptr)
  5342  	case t.IsSlice():
  5343  		elType := types.NewPtr(t.Elem())
  5344  		ptr := s.newValue1(ssa.OpSlicePtr, elType, right)
  5345  		s.store(elType, left, ptr)
  5346  	case t.IsInterface():
  5347  		// itab field is treated as a scalar.
  5348  		idata := s.newValue1(ssa.OpIData, s.f.Config.Types.BytePtr, right)
  5349  		idataAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.BytePtrPtr, s.config.PtrSize, left)
  5350  		s.store(s.f.Config.Types.BytePtr, idataAddr, idata)
  5351  	case t.IsStruct():
  5352  		n := t.NumFields()
  5353  		for i := 0; i < n; i++ {
  5354  			ft := t.FieldType(i)
  5355  			if !ft.HasPointers() {
  5356  				continue
  5357  			}
  5358  			addr := s.newValue1I(ssa.OpOffPtr, ft.PtrTo(), t.FieldOff(i), left)
  5359  			val := s.newValue1I(ssa.OpStructSelect, ft, int64(i), right)
  5360  			s.storeTypePtrs(ft, addr, val)
  5361  		}
  5362  	case t.IsArray() && t.NumElem() == 0:
  5363  		// nothing
  5364  	case t.IsArray() && t.NumElem() == 1:
  5365  		s.storeTypePtrs(t.Elem(), left, s.newValue1I(ssa.OpArraySelect, t.Elem(), 0, right))
  5366  	default:
  5367  		s.Fatalf("bad write barrier type %v", t)
  5368  	}
  5369  }
  5370  
  5371  // putArg evaluates n for the purpose of passing it as an argument to a function and returns the value for the call.
  5372  func (s *state) putArg(n ir.Node, t *types.Type) *ssa.Value {
  5373  	var a *ssa.Value
  5374  	if !ssa.CanSSA(t) {
  5375  		a = s.newValue2(ssa.OpDereference, t, s.addr(n), s.mem())
  5376  	} else {
  5377  		a = s.expr(n)
  5378  	}
  5379  	return a
  5380  }
  5381  
  5382  // slice computes the slice v[i:j:k] and returns ptr, len, and cap of result.
  5383  // i,j,k may be nil, in which case they are set to their default value.
  5384  // v may be a slice, string or pointer to an array.
  5385  func (s *state) slice(v, i, j, k *ssa.Value, bounded bool) (p, l, c *ssa.Value) {
  5386  	t := v.Type
  5387  	var ptr, len, cap *ssa.Value
  5388  	switch {
  5389  	case t.IsSlice():
  5390  		ptr = s.newValue1(ssa.OpSlicePtr, types.NewPtr(t.Elem()), v)
  5391  		len = s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], v)
  5392  		cap = s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], v)
  5393  	case t.IsString():
  5394  		ptr = s.newValue1(ssa.OpStringPtr, types.NewPtr(types.Types[types.TUINT8]), v)
  5395  		len = s.newValue1(ssa.OpStringLen, types.Types[types.TINT], v)
  5396  		cap = len
  5397  	case t.IsPtr():
  5398  		if !t.Elem().IsArray() {
  5399  			s.Fatalf("bad ptr to array in slice %v\n", t)
  5400  		}
  5401  		nv := s.nilCheck(v)
  5402  		ptr = s.newValue1(ssa.OpCopy, types.NewPtr(t.Elem().Elem()), nv)
  5403  		len = s.constInt(types.Types[types.TINT], t.Elem().NumElem())
  5404  		cap = len
  5405  	default:
  5406  		s.Fatalf("bad type in slice %v\n", t)
  5407  	}
  5408  
  5409  	// Set default values
  5410  	if i == nil {
  5411  		i = s.constInt(types.Types[types.TINT], 0)
  5412  	}
  5413  	if j == nil {
  5414  		j = len
  5415  	}
  5416  	three := true
  5417  	if k == nil {
  5418  		three = false
  5419  		k = cap
  5420  	}
  5421  
  5422  	// Panic if slice indices are not in bounds.
  5423  	// Make sure we check these in reverse order so that we're always
  5424  	// comparing against a value known to be nonnegative. See issue 28797.
  5425  	if three {
  5426  		if k != cap {
  5427  			kind := ssa.BoundsSlice3Alen
  5428  			if t.IsSlice() {
  5429  				kind = ssa.BoundsSlice3Acap
  5430  			}
  5431  			k = s.boundsCheck(k, cap, kind, bounded)
  5432  		}
  5433  		if j != k {
  5434  			j = s.boundsCheck(j, k, ssa.BoundsSlice3B, bounded)
  5435  		}
  5436  		i = s.boundsCheck(i, j, ssa.BoundsSlice3C, bounded)
  5437  	} else {
  5438  		if j != k {
  5439  			kind := ssa.BoundsSliceAlen
  5440  			if t.IsSlice() {
  5441  				kind = ssa.BoundsSliceAcap
  5442  			}
  5443  			j = s.boundsCheck(j, k, kind, bounded)
  5444  		}
  5445  		i = s.boundsCheck(i, j, ssa.BoundsSliceB, bounded)
  5446  	}
  5447  
  5448  	// Word-sized integer operations.
  5449  	subOp := s.ssaOp(ir.OSUB, types.Types[types.TINT])
  5450  	mulOp := s.ssaOp(ir.OMUL, types.Types[types.TINT])
  5451  	andOp := s.ssaOp(ir.OAND, types.Types[types.TINT])
  5452  
  5453  	// Calculate the length (rlen) and capacity (rcap) of the new slice.
  5454  	// For strings the capacity of the result is unimportant. However,
  5455  	// we use rcap to test if we've generated a zero-length slice.
  5456  	// Use length of strings for that.
  5457  	rlen := s.newValue2(subOp, types.Types[types.TINT], j, i)
  5458  	rcap := rlen
  5459  	if j != k && !t.IsString() {
  5460  		rcap = s.newValue2(subOp, types.Types[types.TINT], k, i)
  5461  	}
  5462  
  5463  	if (i.Op == ssa.OpConst64 || i.Op == ssa.OpConst32) && i.AuxInt == 0 {
  5464  		// No pointer arithmetic necessary.
  5465  		return ptr, rlen, rcap
  5466  	}
  5467  
  5468  	// Calculate the base pointer (rptr) for the new slice.
  5469  	//
  5470  	// Generate the following code assuming that indexes are in bounds.
  5471  	// The masking is to make sure that we don't generate a slice
  5472  	// that points to the next object in memory. We cannot just set
  5473  	// the pointer to nil because then we would create a nil slice or
  5474  	// string.
  5475  	//
  5476  	//     rcap = k - i
  5477  	//     rlen = j - i
  5478  	//     rptr = ptr + (mask(rcap) & (i * stride))
  5479  	//
  5480  	// Where mask(x) is 0 if x==0 and -1 if x>0 and stride is the width
  5481  	// of the element type.
  5482  	stride := s.constInt(types.Types[types.TINT], ptr.Type.Elem().Size())
  5483  
  5484  	// The delta is the number of bytes to offset ptr by.
  5485  	delta := s.newValue2(mulOp, types.Types[types.TINT], i, stride)
  5486  
  5487  	// If we're slicing to the point where the capacity is zero,
  5488  	// zero out the delta.
  5489  	mask := s.newValue1(ssa.OpSlicemask, types.Types[types.TINT], rcap)
  5490  	delta = s.newValue2(andOp, types.Types[types.TINT], delta, mask)
  5491  
  5492  	// Compute rptr = ptr + delta.
  5493  	rptr := s.newValue2(ssa.OpAddPtr, ptr.Type, ptr, delta)
  5494  
  5495  	return rptr, rlen, rcap
  5496  }
  5497  
  5498  type u642fcvtTab struct {
  5499  	leq, cvt2F, and, rsh, or, add ssa.Op
  5500  	one                           func(*state, *types.Type, int64) *ssa.Value
  5501  }
  5502  
  5503  var u64_f64 = u642fcvtTab{
  5504  	leq:   ssa.OpLeq64,
  5505  	cvt2F: ssa.OpCvt64to64F,
  5506  	and:   ssa.OpAnd64,
  5507  	rsh:   ssa.OpRsh64Ux64,
  5508  	or:    ssa.OpOr64,
  5509  	add:   ssa.OpAdd64F,
  5510  	one:   (*state).constInt64,
  5511  }
  5512  
  5513  var u64_f32 = u642fcvtTab{
  5514  	leq:   ssa.OpLeq64,
  5515  	cvt2F: ssa.OpCvt64to32F,
  5516  	and:   ssa.OpAnd64,
  5517  	rsh:   ssa.OpRsh64Ux64,
  5518  	or:    ssa.OpOr64,
  5519  	add:   ssa.OpAdd32F,
  5520  	one:   (*state).constInt64,
  5521  }
  5522  
  5523  func (s *state) uint64Tofloat64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5524  	return s.uint64Tofloat(&u64_f64, n, x, ft, tt)
  5525  }
  5526  
  5527  func (s *state) uint64Tofloat32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5528  	return s.uint64Tofloat(&u64_f32, n, x, ft, tt)
  5529  }
  5530  
  5531  func (s *state) uint64Tofloat(cvttab *u642fcvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5532  	// if x >= 0 {
  5533  	//    result = (floatY) x
  5534  	// } else {
  5535  	// 	  y = uintX(x) ; y = x & 1
  5536  	// 	  z = uintX(x) ; z = z >> 1
  5537  	// 	  z = z | y
  5538  	// 	  result = floatY(z)
  5539  	// 	  result = result + result
  5540  	// }
  5541  	//
  5542  	// Code borrowed from old code generator.
  5543  	// What's going on: large 64-bit "unsigned" looks like
  5544  	// negative number to hardware's integer-to-float
  5545  	// conversion. However, because the mantissa is only
  5546  	// 63 bits, we don't need the LSB, so instead we do an
  5547  	// unsigned right shift (divide by two), convert, and
  5548  	// double. However, before we do that, we need to be
  5549  	// sure that we do not lose a "1" if that made the
  5550  	// difference in the resulting rounding. Therefore, we
  5551  	// preserve it, and OR (not ADD) it back in. The case
  5552  	// that matters is when the eleven discarded bits are
  5553  	// equal to 10000000001; that rounds up, and the 1 cannot
  5554  	// be lost else it would round down if the LSB of the
  5555  	// candidate mantissa is 0.
  5556  	cmp := s.newValue2(cvttab.leq, types.Types[types.TBOOL], s.zeroVal(ft), x)
  5557  	b := s.endBlock()
  5558  	b.Kind = ssa.BlockIf
  5559  	b.SetControl(cmp)
  5560  	b.Likely = ssa.BranchLikely
  5561  
  5562  	bThen := s.f.NewBlock(ssa.BlockPlain)
  5563  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5564  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5565  
  5566  	b.AddEdgeTo(bThen)
  5567  	s.startBlock(bThen)
  5568  	a0 := s.newValue1(cvttab.cvt2F, tt, x)
  5569  	s.vars[n] = a0
  5570  	s.endBlock()
  5571  	bThen.AddEdgeTo(bAfter)
  5572  
  5573  	b.AddEdgeTo(bElse)
  5574  	s.startBlock(bElse)
  5575  	one := cvttab.one(s, ft, 1)
  5576  	y := s.newValue2(cvttab.and, ft, x, one)
  5577  	z := s.newValue2(cvttab.rsh, ft, x, one)
  5578  	z = s.newValue2(cvttab.or, ft, z, y)
  5579  	a := s.newValue1(cvttab.cvt2F, tt, z)
  5580  	a1 := s.newValue2(cvttab.add, tt, a, a)
  5581  	s.vars[n] = a1
  5582  	s.endBlock()
  5583  	bElse.AddEdgeTo(bAfter)
  5584  
  5585  	s.startBlock(bAfter)
  5586  	return s.variable(n, n.Type())
  5587  }
  5588  
  5589  type u322fcvtTab struct {
  5590  	cvtI2F, cvtF2F ssa.Op
  5591  }
  5592  
  5593  var u32_f64 = u322fcvtTab{
  5594  	cvtI2F: ssa.OpCvt32to64F,
  5595  	cvtF2F: ssa.OpCopy,
  5596  }
  5597  
  5598  var u32_f32 = u322fcvtTab{
  5599  	cvtI2F: ssa.OpCvt32to32F,
  5600  	cvtF2F: ssa.OpCvt64Fto32F,
  5601  }
  5602  
  5603  func (s *state) uint32Tofloat64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5604  	return s.uint32Tofloat(&u32_f64, n, x, ft, tt)
  5605  }
  5606  
  5607  func (s *state) uint32Tofloat32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5608  	return s.uint32Tofloat(&u32_f32, n, x, ft, tt)
  5609  }
  5610  
  5611  func (s *state) uint32Tofloat(cvttab *u322fcvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5612  	// if x >= 0 {
  5613  	// 	result = floatY(x)
  5614  	// } else {
  5615  	// 	result = floatY(float64(x) + (1<<32))
  5616  	// }
  5617  	cmp := s.newValue2(ssa.OpLeq32, types.Types[types.TBOOL], s.zeroVal(ft), x)
  5618  	b := s.endBlock()
  5619  	b.Kind = ssa.BlockIf
  5620  	b.SetControl(cmp)
  5621  	b.Likely = ssa.BranchLikely
  5622  
  5623  	bThen := s.f.NewBlock(ssa.BlockPlain)
  5624  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5625  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5626  
  5627  	b.AddEdgeTo(bThen)
  5628  	s.startBlock(bThen)
  5629  	a0 := s.newValue1(cvttab.cvtI2F, tt, x)
  5630  	s.vars[n] = a0
  5631  	s.endBlock()
  5632  	bThen.AddEdgeTo(bAfter)
  5633  
  5634  	b.AddEdgeTo(bElse)
  5635  	s.startBlock(bElse)
  5636  	a1 := s.newValue1(ssa.OpCvt32to64F, types.Types[types.TFLOAT64], x)
  5637  	twoToThe32 := s.constFloat64(types.Types[types.TFLOAT64], float64(1<<32))
  5638  	a2 := s.newValue2(ssa.OpAdd64F, types.Types[types.TFLOAT64], a1, twoToThe32)
  5639  	a3 := s.newValue1(cvttab.cvtF2F, tt, a2)
  5640  
  5641  	s.vars[n] = a3
  5642  	s.endBlock()
  5643  	bElse.AddEdgeTo(bAfter)
  5644  
  5645  	s.startBlock(bAfter)
  5646  	return s.variable(n, n.Type())
  5647  }
  5648  
  5649  // referenceTypeBuiltin generates code for the len/cap builtins for maps and channels.
  5650  func (s *state) referenceTypeBuiltin(n *ir.UnaryExpr, x *ssa.Value) *ssa.Value {
  5651  	if !n.X.Type().IsMap() && !n.X.Type().IsChan() {
  5652  		s.Fatalf("node must be a map or a channel")
  5653  	}
  5654  	if n.X.Type().IsChan() && n.Op() == ir.OLEN {
  5655  		s.Fatalf("cannot inline len(chan)") // must use runtime.chanlen now
  5656  	}
  5657  	if n.X.Type().IsChan() && n.Op() == ir.OCAP {
  5658  		s.Fatalf("cannot inline cap(chan)") // must use runtime.chancap now
  5659  	}
  5660  	if n.X.Type().IsMap() && n.Op() == ir.OCAP {
  5661  		s.Fatalf("cannot inline cap(map)") // cap(map) does not exist
  5662  	}
  5663  	// if n == nil {
  5664  	//   return 0
  5665  	// } else {
  5666  	//   // len, the actual loadType depends
  5667  	//   return int(*((*loadType)n))
  5668  	//   // cap (chan only, not used for now)
  5669  	//   return *(((*int)n)+1)
  5670  	// }
  5671  	lenType := n.Type()
  5672  	nilValue := s.constNil(types.Types[types.TUINTPTR])
  5673  	cmp := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], x, nilValue)
  5674  	b := s.endBlock()
  5675  	b.Kind = ssa.BlockIf
  5676  	b.SetControl(cmp)
  5677  	b.Likely = ssa.BranchUnlikely
  5678  
  5679  	bThen := s.f.NewBlock(ssa.BlockPlain)
  5680  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5681  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5682  
  5683  	// length/capacity of a nil map/chan is zero
  5684  	b.AddEdgeTo(bThen)
  5685  	s.startBlock(bThen)
  5686  	s.vars[n] = s.zeroVal(lenType)
  5687  	s.endBlock()
  5688  	bThen.AddEdgeTo(bAfter)
  5689  
  5690  	b.AddEdgeTo(bElse)
  5691  	s.startBlock(bElse)
  5692  	switch n.Op() {
  5693  	case ir.OLEN:
  5694  		if n.X.Type().IsMap() {
  5695  			// length is stored in the first word, but needs conversion to int.
  5696  			loadType := reflectdata.MapType().Field(0).Type // uint64
  5697  			load := s.load(loadType, x)
  5698  			s.vars[n] = s.conv(nil, load, loadType, lenType) // integer conversion doesn't need Node
  5699  		} else {
  5700  			// length is stored in the first word for chan, no conversion needed.
  5701  			s.vars[n] = s.load(lenType, x)
  5702  		}
  5703  	case ir.OCAP:
  5704  		// capacity is stored in the second word for chan
  5705  		sw := s.newValue1I(ssa.OpOffPtr, lenType.PtrTo(), lenType.Size(), x)
  5706  		s.vars[n] = s.load(lenType, sw)
  5707  	default:
  5708  		s.Fatalf("op must be OLEN or OCAP")
  5709  	}
  5710  	s.endBlock()
  5711  	bElse.AddEdgeTo(bAfter)
  5712  
  5713  	s.startBlock(bAfter)
  5714  	return s.variable(n, lenType)
  5715  }
  5716  
  5717  type f2uCvtTab struct {
  5718  	ltf, cvt2U, subf, or ssa.Op
  5719  	floatValue           func(*state, *types.Type, float64) *ssa.Value
  5720  	intValue             func(*state, *types.Type, int64) *ssa.Value
  5721  	cutoff               uint64
  5722  }
  5723  
  5724  var f32_u64 = f2uCvtTab{
  5725  	ltf:        ssa.OpLess32F,
  5726  	cvt2U:      ssa.OpCvt32Fto64,
  5727  	subf:       ssa.OpSub32F,
  5728  	or:         ssa.OpOr64,
  5729  	floatValue: (*state).constFloat32,
  5730  	intValue:   (*state).constInt64,
  5731  	cutoff:     1 << 63,
  5732  }
  5733  
  5734  var f64_u64 = f2uCvtTab{
  5735  	ltf:        ssa.OpLess64F,
  5736  	cvt2U:      ssa.OpCvt64Fto64,
  5737  	subf:       ssa.OpSub64F,
  5738  	or:         ssa.OpOr64,
  5739  	floatValue: (*state).constFloat64,
  5740  	intValue:   (*state).constInt64,
  5741  	cutoff:     1 << 63,
  5742  }
  5743  
  5744  var f32_u32 = f2uCvtTab{
  5745  	ltf:        ssa.OpLess32F,
  5746  	cvt2U:      ssa.OpCvt32Fto32,
  5747  	subf:       ssa.OpSub32F,
  5748  	or:         ssa.OpOr32,
  5749  	floatValue: (*state).constFloat32,
  5750  	intValue:   func(s *state, t *types.Type, v int64) *ssa.Value { return s.constInt32(t, int32(v)) },
  5751  	cutoff:     1 << 31,
  5752  }
  5753  
  5754  var f64_u32 = f2uCvtTab{
  5755  	ltf:        ssa.OpLess64F,
  5756  	cvt2U:      ssa.OpCvt64Fto32,
  5757  	subf:       ssa.OpSub64F,
  5758  	or:         ssa.OpOr32,
  5759  	floatValue: (*state).constFloat64,
  5760  	intValue:   func(s *state, t *types.Type, v int64) *ssa.Value { return s.constInt32(t, int32(v)) },
  5761  	cutoff:     1 << 31,
  5762  }
  5763  
  5764  func (s *state) float32ToUint64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5765  	return s.floatToUint(&f32_u64, n, x, ft, tt)
  5766  }
  5767  func (s *state) float64ToUint64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5768  	return s.floatToUint(&f64_u64, n, x, ft, tt)
  5769  }
  5770  
  5771  func (s *state) float32ToUint32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5772  	return s.floatToUint(&f32_u32, n, x, ft, tt)
  5773  }
  5774  
  5775  func (s *state) float64ToUint32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5776  	return s.floatToUint(&f64_u32, n, x, ft, tt)
  5777  }
  5778  
  5779  func (s *state) floatToUint(cvttab *f2uCvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5780  	// cutoff:=1<<(intY_Size-1)
  5781  	// if x < floatX(cutoff) {
  5782  	// 	result = uintY(x)
  5783  	// } else {
  5784  	// 	y = x - floatX(cutoff)
  5785  	// 	z = uintY(y)
  5786  	// 	result = z | -(cutoff)
  5787  	// }
  5788  	cutoff := cvttab.floatValue(s, ft, float64(cvttab.cutoff))
  5789  	cmp := s.newValue2(cvttab.ltf, types.Types[types.TBOOL], x, cutoff)
  5790  	b := s.endBlock()
  5791  	b.Kind = ssa.BlockIf
  5792  	b.SetControl(cmp)
  5793  	b.Likely = ssa.BranchLikely
  5794  
  5795  	bThen := s.f.NewBlock(ssa.BlockPlain)
  5796  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5797  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5798  
  5799  	b.AddEdgeTo(bThen)
  5800  	s.startBlock(bThen)
  5801  	a0 := s.newValue1(cvttab.cvt2U, tt, x)
  5802  	s.vars[n] = a0
  5803  	s.endBlock()
  5804  	bThen.AddEdgeTo(bAfter)
  5805  
  5806  	b.AddEdgeTo(bElse)
  5807  	s.startBlock(bElse)
  5808  	y := s.newValue2(cvttab.subf, ft, x, cutoff)
  5809  	y = s.newValue1(cvttab.cvt2U, tt, y)
  5810  	z := cvttab.intValue(s, tt, int64(-cvttab.cutoff))
  5811  	a1 := s.newValue2(cvttab.or, tt, y, z)
  5812  	s.vars[n] = a1
  5813  	s.endBlock()
  5814  	bElse.AddEdgeTo(bAfter)
  5815  
  5816  	s.startBlock(bAfter)
  5817  	return s.variable(n, n.Type())
  5818  }
  5819  
  5820  // dottype generates SSA for a type assertion node.
  5821  // commaok indicates whether to panic or return a bool.
  5822  // If commaok is false, resok will be nil.
  5823  func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
  5824  	iface := s.expr(n.X)              // input interface
  5825  	target := s.reflectType(n.Type()) // target type
  5826  	var targetItab *ssa.Value
  5827  	if n.ITab != nil {
  5828  		targetItab = s.expr(n.ITab)
  5829  	}
  5830  	return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, nil, target, targetItab, commaok, n.Descriptor)
  5831  }
  5832  
  5833  func (s *state) dynamicDottype(n *ir.DynamicTypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
  5834  	iface := s.expr(n.X)
  5835  	var source, target, targetItab *ssa.Value
  5836  	if n.SrcRType != nil {
  5837  		source = s.expr(n.SrcRType)
  5838  	}
  5839  	if !n.X.Type().IsEmptyInterface() && !n.Type().IsInterface() {
  5840  		byteptr := s.f.Config.Types.BytePtr
  5841  		targetItab = s.expr(n.ITab)
  5842  		// TODO(mdempsky): Investigate whether compiling n.RType could be
  5843  		// better than loading itab.typ.
  5844  		target = s.load(byteptr, s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), targetItab))
  5845  	} else {
  5846  		target = s.expr(n.RType)
  5847  	}
  5848  	return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, source, target, targetItab, commaok, nil)
  5849  }
  5850  
  5851  // dottype1 implements a x.(T) operation. iface is the argument (x), dst is the type we're asserting to (T)
  5852  // and src is the type we're asserting from.
  5853  // source is the *runtime._type of src
  5854  // target is the *runtime._type of dst.
  5855  // If src is a nonempty interface and dst is not an interface, targetItab is an itab representing (dst, src). Otherwise it is nil.
  5856  // commaok is true if the caller wants a boolean success value. Otherwise, the generated code panics if the conversion fails.
  5857  // descriptor is a compiler-allocated internal/abi.TypeAssert whose address is passed to runtime.typeAssert when
  5858  // the target type is a compile-time-known non-empty interface. It may be nil.
  5859  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) {
  5860  	typs := s.f.Config.Types
  5861  	byteptr := typs.BytePtr
  5862  	if dst.IsInterface() {
  5863  		if dst.IsEmptyInterface() {
  5864  			// Converting to an empty interface.
  5865  			// Input could be an empty or nonempty interface.
  5866  			if base.Debug.TypeAssert > 0 {
  5867  				base.WarnfAt(pos, "type assertion inlined")
  5868  			}
  5869  
  5870  			// Get itab/type field from input.
  5871  			itab := s.newValue1(ssa.OpITab, byteptr, iface)
  5872  			// Conversion succeeds iff that field is not nil.
  5873  			cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  5874  
  5875  			if src.IsEmptyInterface() && commaok {
  5876  				// Converting empty interface to empty interface with ,ok is just a nil check.
  5877  				return iface, cond
  5878  			}
  5879  
  5880  			// Branch on nilness.
  5881  			b := s.endBlock()
  5882  			b.Kind = ssa.BlockIf
  5883  			b.SetControl(cond)
  5884  			b.Likely = ssa.BranchLikely
  5885  			bOk := s.f.NewBlock(ssa.BlockPlain)
  5886  			bFail := s.f.NewBlock(ssa.BlockPlain)
  5887  			b.AddEdgeTo(bOk)
  5888  			b.AddEdgeTo(bFail)
  5889  
  5890  			if !commaok {
  5891  				// On failure, panic by calling panicnildottype.
  5892  				s.startBlock(bFail)
  5893  				s.rtcall(ir.Syms.Panicnildottype, false, nil, target)
  5894  
  5895  				// On success, return (perhaps modified) input interface.
  5896  				s.startBlock(bOk)
  5897  				if src.IsEmptyInterface() {
  5898  					res = iface // Use input interface unchanged.
  5899  					return
  5900  				}
  5901  				// Load type out of itab, build interface with existing idata.
  5902  				off := s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab)
  5903  				typ := s.load(byteptr, off)
  5904  				idata := s.newValue1(ssa.OpIData, byteptr, iface)
  5905  				res = s.newValue2(ssa.OpIMake, dst, typ, idata)
  5906  				return
  5907  			}
  5908  
  5909  			s.startBlock(bOk)
  5910  			// nonempty -> empty
  5911  			// Need to load type from itab
  5912  			off := s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab)
  5913  			s.vars[typVar] = s.load(byteptr, off)
  5914  			s.endBlock()
  5915  
  5916  			// itab is nil, might as well use that as the nil result.
  5917  			s.startBlock(bFail)
  5918  			s.vars[typVar] = itab
  5919  			s.endBlock()
  5920  
  5921  			// Merge point.
  5922  			bEnd := s.f.NewBlock(ssa.BlockPlain)
  5923  			bOk.AddEdgeTo(bEnd)
  5924  			bFail.AddEdgeTo(bEnd)
  5925  			s.startBlock(bEnd)
  5926  			idata := s.newValue1(ssa.OpIData, byteptr, iface)
  5927  			res = s.newValue2(ssa.OpIMake, dst, s.variable(typVar, byteptr), idata)
  5928  			resok = cond
  5929  			delete(s.vars, typVar) // no practical effect, just to indicate typVar is no longer live.
  5930  			return
  5931  		}
  5932  		// converting to a nonempty interface needs a runtime call.
  5933  		if base.Debug.TypeAssert > 0 {
  5934  			base.WarnfAt(pos, "type assertion not inlined")
  5935  		}
  5936  
  5937  		itab := s.newValue1(ssa.OpITab, byteptr, iface)
  5938  		data := s.newValue1(ssa.OpIData, types.Types[types.TUNSAFEPTR], iface)
  5939  
  5940  		// First, check for nil.
  5941  		bNil := s.f.NewBlock(ssa.BlockPlain)
  5942  		bNonNil := s.f.NewBlock(ssa.BlockPlain)
  5943  		bMerge := s.f.NewBlock(ssa.BlockPlain)
  5944  		cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  5945  		b := s.endBlock()
  5946  		b.Kind = ssa.BlockIf
  5947  		b.SetControl(cond)
  5948  		b.Likely = ssa.BranchLikely
  5949  		b.AddEdgeTo(bNonNil)
  5950  		b.AddEdgeTo(bNil)
  5951  
  5952  		s.startBlock(bNil)
  5953  		if commaok {
  5954  			s.vars[typVar] = itab // which will be nil
  5955  			b := s.endBlock()
  5956  			b.AddEdgeTo(bMerge)
  5957  		} else {
  5958  			// Panic if input is nil.
  5959  			s.rtcall(ir.Syms.Panicnildottype, false, nil, target)
  5960  		}
  5961  
  5962  		// Get typ, possibly by loading out of itab.
  5963  		s.startBlock(bNonNil)
  5964  		typ := itab
  5965  		if !src.IsEmptyInterface() {
  5966  			typ = s.load(byteptr, s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab))
  5967  		}
  5968  
  5969  		// Check the cache first.
  5970  		var d *ssa.Value
  5971  		if descriptor != nil {
  5972  			d = s.newValue1A(ssa.OpAddr, byteptr, descriptor, s.sb)
  5973  			if base.Flag.N == 0 && rtabi.UseInterfaceSwitchCache(Arch.LinkArch.Family) {
  5974  				// Note: we can only use the cache if we have the right atomic load instruction.
  5975  				// Double-check that here.
  5976  				if intrinsics.lookup(Arch.LinkArch.Arch, "internal/runtime/atomic", "Loadp") == nil {
  5977  					s.Fatalf("atomic load not available")
  5978  				}
  5979  				// Pick right size ops.
  5980  				var mul, and, add, zext ssa.Op
  5981  				if s.config.PtrSize == 4 {
  5982  					mul = ssa.OpMul32
  5983  					and = ssa.OpAnd32
  5984  					add = ssa.OpAdd32
  5985  					zext = ssa.OpCopy
  5986  				} else {
  5987  					mul = ssa.OpMul64
  5988  					and = ssa.OpAnd64
  5989  					add = ssa.OpAdd64
  5990  					zext = ssa.OpZeroExt32to64
  5991  				}
  5992  
  5993  				loopHead := s.f.NewBlock(ssa.BlockPlain)
  5994  				loopBody := s.f.NewBlock(ssa.BlockPlain)
  5995  				cacheHit := s.f.NewBlock(ssa.BlockPlain)
  5996  				cacheMiss := s.f.NewBlock(ssa.BlockPlain)
  5997  
  5998  				// Load cache pointer out of descriptor, with an atomic load so
  5999  				// we ensure that we see a fully written cache.
  6000  				atomicLoad := s.newValue2(ssa.OpAtomicLoadPtr, types.NewTuple(typs.BytePtr, types.TypeMem), d, s.mem())
  6001  				cache := s.newValue1(ssa.OpSelect0, typs.BytePtr, atomicLoad)
  6002  				s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, atomicLoad)
  6003  
  6004  				// Load hash from type or itab.
  6005  				var hash *ssa.Value
  6006  				if src.IsEmptyInterface() {
  6007  					hash = s.newValue2(ssa.OpLoad, typs.UInt32, s.newValue1I(ssa.OpOffPtr, typs.UInt32Ptr, rttype.Type.OffsetOf("Hash"), typ), s.mem())
  6008  				} else {
  6009  					hash = s.newValue2(ssa.OpLoad, typs.UInt32, s.newValue1I(ssa.OpOffPtr, typs.UInt32Ptr, rttype.ITab.OffsetOf("Hash"), itab), s.mem())
  6010  				}
  6011  				hash = s.newValue1(zext, typs.Uintptr, hash)
  6012  				s.vars[hashVar] = hash
  6013  				// Load mask from cache.
  6014  				mask := s.newValue2(ssa.OpLoad, typs.Uintptr, cache, s.mem())
  6015  				// Jump to loop head.
  6016  				b := s.endBlock()
  6017  				b.AddEdgeTo(loopHead)
  6018  
  6019  				// At loop head, get pointer to the cache entry.
  6020  				//   e := &cache.Entries[hash&mask]
  6021  				s.startBlock(loopHead)
  6022  				idx := s.newValue2(and, typs.Uintptr, s.variable(hashVar, typs.Uintptr), mask)
  6023  				idx = s.newValue2(mul, typs.Uintptr, idx, s.uintptrConstant(uint64(2*s.config.PtrSize)))
  6024  				idx = s.newValue2(add, typs.Uintptr, idx, s.uintptrConstant(uint64(s.config.PtrSize)))
  6025  				e := s.newValue2(ssa.OpAddPtr, typs.UintptrPtr, cache, idx)
  6026  				//   hash++
  6027  				s.vars[hashVar] = s.newValue2(add, typs.Uintptr, s.variable(hashVar, typs.Uintptr), s.uintptrConstant(1))
  6028  
  6029  				// Look for a cache hit.
  6030  				//   if e.Typ == typ { goto hit }
  6031  				eTyp := s.newValue2(ssa.OpLoad, typs.Uintptr, e, s.mem())
  6032  				cmp1 := s.newValue2(ssa.OpEqPtr, typs.Bool, typ, eTyp)
  6033  				b = s.endBlock()
  6034  				b.Kind = ssa.BlockIf
  6035  				b.SetControl(cmp1)
  6036  				b.AddEdgeTo(cacheHit)
  6037  				b.AddEdgeTo(loopBody)
  6038  
  6039  				// Look for an empty entry, the tombstone for this hash table.
  6040  				//   if e.Typ == nil { goto miss }
  6041  				s.startBlock(loopBody)
  6042  				cmp2 := s.newValue2(ssa.OpEqPtr, typs.Bool, eTyp, s.constNil(typs.BytePtr))
  6043  				b = s.endBlock()
  6044  				b.Kind = ssa.BlockIf
  6045  				b.SetControl(cmp2)
  6046  				b.AddEdgeTo(cacheMiss)
  6047  				b.AddEdgeTo(loopHead)
  6048  
  6049  				// On a hit, load the data fields of the cache entry.
  6050  				//   Itab = e.Itab
  6051  				s.startBlock(cacheHit)
  6052  				eItab := s.newValue2(ssa.OpLoad, typs.BytePtr, s.newValue1I(ssa.OpOffPtr, typs.BytePtrPtr, s.config.PtrSize, e), s.mem())
  6053  				s.vars[typVar] = eItab
  6054  				b = s.endBlock()
  6055  				b.AddEdgeTo(bMerge)
  6056  
  6057  				// On a miss, call into the runtime to get the answer.
  6058  				s.startBlock(cacheMiss)
  6059  			}
  6060  		}
  6061  
  6062  		// Call into runtime to get itab for result.
  6063  		if descriptor != nil {
  6064  			itab = s.rtcall(ir.Syms.TypeAssert, true, []*types.Type{byteptr}, d, typ)[0]
  6065  		} else {
  6066  			var fn *obj.LSym
  6067  			if commaok {
  6068  				fn = ir.Syms.AssertE2I2
  6069  			} else {
  6070  				fn = ir.Syms.AssertE2I
  6071  			}
  6072  			itab = s.rtcall(fn, true, []*types.Type{byteptr}, target, typ)[0]
  6073  		}
  6074  		s.vars[typVar] = itab
  6075  		b = s.endBlock()
  6076  		b.AddEdgeTo(bMerge)
  6077  
  6078  		// Build resulting interface.
  6079  		s.startBlock(bMerge)
  6080  		itab = s.variable(typVar, byteptr)
  6081  		var ok *ssa.Value
  6082  		if commaok {
  6083  			ok = s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  6084  		}
  6085  		return s.newValue2(ssa.OpIMake, dst, itab, data), ok
  6086  	}
  6087  
  6088  	if base.Debug.TypeAssert > 0 {
  6089  		base.WarnfAt(pos, "type assertion inlined")
  6090  	}
  6091  
  6092  	// Converting to a concrete type.
  6093  	direct := types.IsDirectIface(dst)
  6094  	itab := s.newValue1(ssa.OpITab, byteptr, iface) // type word of interface
  6095  	if base.Debug.TypeAssert > 0 {
  6096  		base.WarnfAt(pos, "type assertion inlined")
  6097  	}
  6098  	var wantedFirstWord *ssa.Value
  6099  	if src.IsEmptyInterface() {
  6100  		// Looking for pointer to target type.
  6101  		wantedFirstWord = target
  6102  	} else {
  6103  		// Looking for pointer to itab for target type and source interface.
  6104  		wantedFirstWord = targetItab
  6105  	}
  6106  
  6107  	var tmp ir.Node     // temporary for use with large types
  6108  	var addr *ssa.Value // address of tmp
  6109  	if commaok && !ssa.CanSSA(dst) {
  6110  		// unSSAable type, use temporary.
  6111  		// TODO: get rid of some of these temporaries.
  6112  		tmp, addr = s.temp(pos, dst)
  6113  	}
  6114  
  6115  	cond := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], itab, wantedFirstWord)
  6116  	b := s.endBlock()
  6117  	b.Kind = ssa.BlockIf
  6118  	b.SetControl(cond)
  6119  	b.Likely = ssa.BranchLikely
  6120  
  6121  	bOk := s.f.NewBlock(ssa.BlockPlain)
  6122  	bFail := s.f.NewBlock(ssa.BlockPlain)
  6123  	b.AddEdgeTo(bOk)
  6124  	b.AddEdgeTo(bFail)
  6125  
  6126  	if !commaok {
  6127  		// on failure, panic by calling panicdottype
  6128  		s.startBlock(bFail)
  6129  		taddr := source
  6130  		if taddr == nil {
  6131  			taddr = s.reflectType(src)
  6132  		}
  6133  		if src.IsEmptyInterface() {
  6134  			s.rtcall(ir.Syms.PanicdottypeE, false, nil, itab, target, taddr)
  6135  		} else {
  6136  			s.rtcall(ir.Syms.PanicdottypeI, false, nil, itab, target, taddr)
  6137  		}
  6138  
  6139  		// on success, return data from interface
  6140  		s.startBlock(bOk)
  6141  		if direct {
  6142  			return s.newValue1(ssa.OpIData, dst, iface), nil
  6143  		}
  6144  		p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
  6145  		return s.load(dst, p), nil
  6146  	}
  6147  
  6148  	// commaok is the more complicated case because we have
  6149  	// a control flow merge point.
  6150  	bEnd := s.f.NewBlock(ssa.BlockPlain)
  6151  	// Note that we need a new valVar each time (unlike okVar where we can
  6152  	// reuse the variable) because it might have a different type every time.
  6153  	valVar := ssaMarker("val")
  6154  
  6155  	// type assertion succeeded
  6156  	s.startBlock(bOk)
  6157  	if tmp == nil {
  6158  		if direct {
  6159  			s.vars[valVar] = s.newValue1(ssa.OpIData, dst, iface)
  6160  		} else {
  6161  			p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
  6162  			s.vars[valVar] = s.load(dst, p)
  6163  		}
  6164  	} else {
  6165  		p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
  6166  		s.move(dst, addr, p)
  6167  	}
  6168  	s.vars[okVar] = s.constBool(true)
  6169  	s.endBlock()
  6170  	bOk.AddEdgeTo(bEnd)
  6171  
  6172  	// type assertion failed
  6173  	s.startBlock(bFail)
  6174  	if tmp == nil {
  6175  		s.vars[valVar] = s.zeroVal(dst)
  6176  	} else {
  6177  		s.zero(dst, addr)
  6178  	}
  6179  	s.vars[okVar] = s.constBool(false)
  6180  	s.endBlock()
  6181  	bFail.AddEdgeTo(bEnd)
  6182  
  6183  	// merge point
  6184  	s.startBlock(bEnd)
  6185  	if tmp == nil {
  6186  		res = s.variable(valVar, dst)
  6187  		delete(s.vars, valVar) // no practical effect, just to indicate typVar is no longer live.
  6188  	} else {
  6189  		res = s.load(dst, addr)
  6190  	}
  6191  	resok = s.variable(okVar, types.Types[types.TBOOL])
  6192  	delete(s.vars, okVar) // ditto
  6193  	return res, resok
  6194  }
  6195  
  6196  // temp allocates a temp of type t at position pos
  6197  func (s *state) temp(pos src.XPos, t *types.Type) (*ir.Name, *ssa.Value) {
  6198  	tmp := typecheck.TempAt(pos, s.curfn, t)
  6199  	if t.HasPointers() || (ssa.IsMergeCandidate(tmp) && t != deferstruct()) {
  6200  		s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, tmp, s.mem())
  6201  	}
  6202  	addr := s.addr(tmp)
  6203  	return tmp, addr
  6204  }
  6205  
  6206  // variable returns the value of a variable at the current location.
  6207  func (s *state) variable(n ir.Node, t *types.Type) *ssa.Value {
  6208  	v := s.vars[n]
  6209  	if v != nil {
  6210  		return v
  6211  	}
  6212  	v = s.fwdVars[n]
  6213  	if v != nil {
  6214  		return v
  6215  	}
  6216  
  6217  	if s.curBlock == s.f.Entry {
  6218  		// No variable should be live at entry.
  6219  		s.f.Fatalf("value %v (%v) incorrectly live at entry", n, v)
  6220  	}
  6221  	// Make a FwdRef, which records a value that's live on block input.
  6222  	// We'll find the matching definition as part of insertPhis.
  6223  	v = s.newValue0A(ssa.OpFwdRef, t, fwdRefAux{N: n})
  6224  	s.fwdVars[n] = v
  6225  	if n.Op() == ir.ONAME {
  6226  		s.addNamedValue(n.(*ir.Name), v)
  6227  	}
  6228  	return v
  6229  }
  6230  
  6231  func (s *state) mem() *ssa.Value {
  6232  	return s.variable(memVar, types.TypeMem)
  6233  }
  6234  
  6235  func (s *state) addNamedValue(n *ir.Name, v *ssa.Value) {
  6236  	if n.Class == ir.Pxxx {
  6237  		// Don't track our marker nodes (memVar etc.).
  6238  		return
  6239  	}
  6240  	if ir.IsAutoTmp(n) {
  6241  		// Don't track temporary variables.
  6242  		return
  6243  	}
  6244  	if n.Class == ir.PPARAMOUT {
  6245  		// Don't track named output values.  This prevents return values
  6246  		// from being assigned too early. See #14591 and #14762. TODO: allow this.
  6247  		return
  6248  	}
  6249  	loc := ssa.LocalSlot{N: n, Type: n.Type(), Off: 0}
  6250  	values, ok := s.f.NamedValues[loc]
  6251  	if !ok {
  6252  		s.f.Names = append(s.f.Names, &loc)
  6253  		s.f.CanonicalLocalSlots[loc] = &loc
  6254  	}
  6255  	s.f.NamedValues[loc] = append(values, v)
  6256  }
  6257  
  6258  // Branch is an unresolved branch.
  6259  type Branch struct {
  6260  	P *obj.Prog  // branch instruction
  6261  	B *ssa.Block // target
  6262  }
  6263  
  6264  // State contains state needed during Prog generation.
  6265  type State struct {
  6266  	ABI obj.ABI
  6267  
  6268  	pp *objw.Progs
  6269  
  6270  	// Branches remembers all the branch instructions we've seen
  6271  	// and where they would like to go.
  6272  	Branches []Branch
  6273  
  6274  	// JumpTables remembers all the jump tables we've seen.
  6275  	JumpTables []*ssa.Block
  6276  
  6277  	// bstart remembers where each block starts (indexed by block ID)
  6278  	bstart []*obj.Prog
  6279  
  6280  	maxarg int64 // largest frame size for arguments to calls made by the function
  6281  
  6282  	// Map from GC safe points to liveness index, generated by
  6283  	// liveness analysis.
  6284  	livenessMap liveness.Map
  6285  
  6286  	// partLiveArgs includes arguments that may be partially live, for which we
  6287  	// need to generate instructions that spill the argument registers.
  6288  	partLiveArgs map[*ir.Name]bool
  6289  
  6290  	// lineRunStart records the beginning of the current run of instructions
  6291  	// within a single block sharing the same line number
  6292  	// Used to move statement marks to the beginning of such runs.
  6293  	lineRunStart *obj.Prog
  6294  
  6295  	// wasm: The number of values on the WebAssembly stack. This is only used as a safeguard.
  6296  	OnWasmStackSkipped int
  6297  }
  6298  
  6299  func (s *State) FuncInfo() *obj.FuncInfo {
  6300  	return s.pp.CurFunc.LSym.Func()
  6301  }
  6302  
  6303  // Prog appends a new Prog.
  6304  func (s *State) Prog(as obj.As) *obj.Prog {
  6305  	p := s.pp.Prog(as)
  6306  	if objw.LosesStmtMark(as) {
  6307  		return p
  6308  	}
  6309  	// Float a statement start to the beginning of any same-line run.
  6310  	// lineRunStart is reset at block boundaries, which appears to work well.
  6311  	if s.lineRunStart == nil || s.lineRunStart.Pos.Line() != p.Pos.Line() {
  6312  		s.lineRunStart = p
  6313  	} else if p.Pos.IsStmt() == src.PosIsStmt {
  6314  		s.lineRunStart.Pos = s.lineRunStart.Pos.WithIsStmt()
  6315  		p.Pos = p.Pos.WithNotStmt()
  6316  	}
  6317  	return p
  6318  }
  6319  
  6320  // Pc returns the current Prog.
  6321  func (s *State) Pc() *obj.Prog {
  6322  	return s.pp.Next
  6323  }
  6324  
  6325  // SetPos sets the current source position.
  6326  func (s *State) SetPos(pos src.XPos) {
  6327  	s.pp.Pos = pos
  6328  }
  6329  
  6330  // Br emits a single branch instruction and returns the instruction.
  6331  // Not all architectures need the returned instruction, but otherwise
  6332  // the boilerplate is common to all.
  6333  func (s *State) Br(op obj.As, target *ssa.Block) *obj.Prog {
  6334  	p := s.Prog(op)
  6335  	p.To.Type = obj.TYPE_BRANCH
  6336  	s.Branches = append(s.Branches, Branch{P: p, B: target})
  6337  	return p
  6338  }
  6339  
  6340  // DebugFriendlySetPosFrom adjusts Pos.IsStmt subject to heuristics
  6341  // that reduce "jumpy" line number churn when debugging.
  6342  // Spill/fill/copy instructions from the register allocator,
  6343  // phi functions, and instructions with a no-pos position
  6344  // are examples of instructions that can cause churn.
  6345  func (s *State) DebugFriendlySetPosFrom(v *ssa.Value) {
  6346  	switch v.Op {
  6347  	case ssa.OpPhi, ssa.OpCopy, ssa.OpLoadReg, ssa.OpStoreReg:
  6348  		// These are not statements
  6349  		s.SetPos(v.Pos.WithNotStmt())
  6350  	default:
  6351  		p := v.Pos
  6352  		if p != src.NoXPos {
  6353  			// If the position is defined, update the position.
  6354  			// Also convert default IsStmt to NotStmt; only
  6355  			// explicit statement boundaries should appear
  6356  			// in the generated code.
  6357  			if p.IsStmt() != src.PosIsStmt {
  6358  				if s.pp.Pos.IsStmt() == src.PosIsStmt && s.pp.Pos.SameFileAndLine(p) {
  6359  					// If s.pp.Pos already has a statement mark, then it was set here (below) for
  6360  					// the previous value.  If an actual instruction had been emitted for that
  6361  					// value, then the statement mark would have been reset.  Since the statement
  6362  					// mark of s.pp.Pos was not reset, this position (file/line) still needs a
  6363  					// statement mark on an instruction.  If file and line for this value are
  6364  					// the same as the previous value, then the first instruction for this
  6365  					// value will work to take the statement mark.  Return early to avoid
  6366  					// resetting the statement mark.
  6367  					//
  6368  					// The reset of s.pp.Pos occurs in (*Progs).Prog() -- if it emits
  6369  					// an instruction, and the instruction's statement mark was set,
  6370  					// and it is not one of the LosesStmtMark instructions,
  6371  					// then Prog() resets the statement mark on the (*Progs).Pos.
  6372  					return
  6373  				}
  6374  				p = p.WithNotStmt()
  6375  				// Calls use the pos attached to v, but copy the statement mark from State
  6376  			}
  6377  			s.SetPos(p)
  6378  		} else {
  6379  			s.SetPos(s.pp.Pos.WithNotStmt())
  6380  		}
  6381  	}
  6382  }
  6383  
  6384  // emit argument info (locations on stack) for traceback.
  6385  func emitArgInfo(e *ssafn, f *ssa.Func, pp *objw.Progs) {
  6386  	ft := e.curfn.Type()
  6387  	if ft.NumRecvs() == 0 && ft.NumParams() == 0 {
  6388  		return
  6389  	}
  6390  
  6391  	x := EmitArgInfo(e.curfn, f.OwnAux.ABIInfo())
  6392  	x.Set(obj.AttrContentAddressable, true)
  6393  	e.curfn.LSym.Func().ArgInfo = x
  6394  
  6395  	// Emit a funcdata pointing at the arg info data.
  6396  	p := pp.Prog(obj.AFUNCDATA)
  6397  	p.From.SetConst(rtabi.FUNCDATA_ArgInfo)
  6398  	p.To.Type = obj.TYPE_MEM
  6399  	p.To.Name = obj.NAME_EXTERN
  6400  	p.To.Sym = x
  6401  }
  6402  
  6403  // emit argument info (locations on stack) of f for traceback.
  6404  func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
  6405  	x := base.Ctxt.Lookup(fmt.Sprintf("%s.arginfo%d", f.LSym.Name, f.ABI))
  6406  	// NOTE: do not set ContentAddressable here. This may be referenced from
  6407  	// assembly code by name (in this case f is a declaration).
  6408  	// Instead, set it in emitArgInfo above.
  6409  
  6410  	PtrSize := int64(types.PtrSize)
  6411  	uintptrTyp := types.Types[types.TUINTPTR]
  6412  
  6413  	isAggregate := func(t *types.Type) bool {
  6414  		return t.IsStruct() || t.IsArray() || t.IsComplex() || t.IsInterface() || t.IsString() || t.IsSlice()
  6415  	}
  6416  
  6417  	wOff := 0
  6418  	n := 0
  6419  	writebyte := func(o uint8) { wOff = objw.Uint8(x, wOff, o) }
  6420  
  6421  	// Write one non-aggregate arg/field/element.
  6422  	write1 := func(sz, offset int64) {
  6423  		if offset >= rtabi.TraceArgsSpecial {
  6424  			writebyte(rtabi.TraceArgsOffsetTooLarge)
  6425  		} else {
  6426  			writebyte(uint8(offset))
  6427  			writebyte(uint8(sz))
  6428  		}
  6429  		n++
  6430  	}
  6431  
  6432  	// Visit t recursively and write it out.
  6433  	// Returns whether to continue visiting.
  6434  	var visitType func(baseOffset int64, t *types.Type, depth int) bool
  6435  	visitType = func(baseOffset int64, t *types.Type, depth int) bool {
  6436  		if n >= rtabi.TraceArgsLimit {
  6437  			writebyte(rtabi.TraceArgsDotdotdot)
  6438  			return false
  6439  		}
  6440  		if !isAggregate(t) {
  6441  			write1(t.Size(), baseOffset)
  6442  			return true
  6443  		}
  6444  		writebyte(rtabi.TraceArgsStartAgg)
  6445  		depth++
  6446  		if depth >= rtabi.TraceArgsMaxDepth {
  6447  			writebyte(rtabi.TraceArgsDotdotdot)
  6448  			writebyte(rtabi.TraceArgsEndAgg)
  6449  			n++
  6450  			return true
  6451  		}
  6452  		switch {
  6453  		case t.IsInterface(), t.IsString():
  6454  			_ = visitType(baseOffset, uintptrTyp, depth) &&
  6455  				visitType(baseOffset+PtrSize, uintptrTyp, depth)
  6456  		case t.IsSlice():
  6457  			_ = visitType(baseOffset, uintptrTyp, depth) &&
  6458  				visitType(baseOffset+PtrSize, uintptrTyp, depth) &&
  6459  				visitType(baseOffset+PtrSize*2, uintptrTyp, depth)
  6460  		case t.IsComplex():
  6461  			_ = visitType(baseOffset, types.FloatForComplex(t), depth) &&
  6462  				visitType(baseOffset+t.Size()/2, types.FloatForComplex(t), depth)
  6463  		case t.IsArray():
  6464  			if t.NumElem() == 0 {
  6465  				n++ // {} counts as a component
  6466  				break
  6467  			}
  6468  			for i := int64(0); i < t.NumElem(); i++ {
  6469  				if !visitType(baseOffset, t.Elem(), depth) {
  6470  					break
  6471  				}
  6472  				baseOffset += t.Elem().Size()
  6473  			}
  6474  		case t.IsStruct():
  6475  			if t.NumFields() == 0 {
  6476  				n++ // {} counts as a component
  6477  				break
  6478  			}
  6479  			for _, field := range t.Fields() {
  6480  				if !visitType(baseOffset+field.Offset, field.Type, depth) {
  6481  					break
  6482  				}
  6483  			}
  6484  		}
  6485  		writebyte(rtabi.TraceArgsEndAgg)
  6486  		return true
  6487  	}
  6488  
  6489  	start := 0
  6490  	if strings.Contains(f.LSym.Name, "[") {
  6491  		// Skip the dictionary argument - it is implicit and the user doesn't need to see it.
  6492  		start = 1
  6493  	}
  6494  
  6495  	for _, a := range abiInfo.InParams()[start:] {
  6496  		if !visitType(a.FrameOffset(abiInfo), a.Type, 0) {
  6497  			break
  6498  		}
  6499  	}
  6500  	writebyte(rtabi.TraceArgsEndSeq)
  6501  	if wOff > rtabi.TraceArgsMaxLen {
  6502  		base.Fatalf("ArgInfo too large")
  6503  	}
  6504  
  6505  	return x
  6506  }
  6507  
  6508  // for wrapper, emit info of wrapped function.
  6509  func emitWrappedFuncInfo(e *ssafn, pp *objw.Progs) {
  6510  	if base.Ctxt.Flag_linkshared {
  6511  		// Relative reference (SymPtrOff) to another shared object doesn't work.
  6512  		// Unfortunate.
  6513  		return
  6514  	}
  6515  
  6516  	wfn := e.curfn.WrappedFunc
  6517  	if wfn == nil {
  6518  		return
  6519  	}
  6520  
  6521  	wsym := wfn.Linksym()
  6522  	x := base.Ctxt.LookupInit(fmt.Sprintf("%s.wrapinfo", wsym.Name), func(x *obj.LSym) {
  6523  		objw.SymPtrOff(x, 0, wsym)
  6524  		x.Set(obj.AttrContentAddressable, true)
  6525  	})
  6526  	e.curfn.LSym.Func().WrapInfo = x
  6527  
  6528  	// Emit a funcdata pointing at the wrap info data.
  6529  	p := pp.Prog(obj.AFUNCDATA)
  6530  	p.From.SetConst(rtabi.FUNCDATA_WrapInfo)
  6531  	p.To.Type = obj.TYPE_MEM
  6532  	p.To.Name = obj.NAME_EXTERN
  6533  	p.To.Sym = x
  6534  }
  6535  
  6536  // genssa appends entries to pp for each instruction in f.
  6537  func genssa(f *ssa.Func, pp *objw.Progs) {
  6538  	var s State
  6539  	s.ABI = f.OwnAux.Fn.ABI()
  6540  
  6541  	e := f.Frontend().(*ssafn)
  6542  
  6543  	gatherPrintInfo := f.PrintOrHtmlSSA || ssa.GenssaDump[f.Name]
  6544  
  6545  	var lv *liveness.Liveness
  6546  	s.livenessMap, s.partLiveArgs, lv = liveness.Compute(e.curfn, f, e.stkptrsize, pp, gatherPrintInfo)
  6547  	emitArgInfo(e, f, pp)
  6548  	argLiveBlockMap, argLiveValueMap := liveness.ArgLiveness(e.curfn, f, pp)
  6549  
  6550  	openDeferInfo := e.curfn.LSym.Func().OpenCodedDeferInfo
  6551  	if openDeferInfo != nil {
  6552  		// This function uses open-coded defers -- write out the funcdata
  6553  		// info that we computed at the end of genssa.
  6554  		p := pp.Prog(obj.AFUNCDATA)
  6555  		p.From.SetConst(rtabi.FUNCDATA_OpenCodedDeferInfo)
  6556  		p.To.Type = obj.TYPE_MEM
  6557  		p.To.Name = obj.NAME_EXTERN
  6558  		p.To.Sym = openDeferInfo
  6559  	}
  6560  
  6561  	emitWrappedFuncInfo(e, pp)
  6562  
  6563  	// Remember where each block starts.
  6564  	s.bstart = make([]*obj.Prog, f.NumBlocks())
  6565  	s.pp = pp
  6566  	var progToValue map[*obj.Prog]*ssa.Value
  6567  	var progToBlock map[*obj.Prog]*ssa.Block
  6568  	var valueToProgAfter []*obj.Prog // The first Prog following computation of a value v; v is visible at this point.
  6569  	if gatherPrintInfo {
  6570  		progToValue = make(map[*obj.Prog]*ssa.Value, f.NumValues())
  6571  		progToBlock = make(map[*obj.Prog]*ssa.Block, f.NumBlocks())
  6572  		f.Logf("genssa %s\n", f.Name)
  6573  		progToBlock[s.pp.Next] = f.Blocks[0]
  6574  	}
  6575  
  6576  	if base.Ctxt.Flag_locationlists {
  6577  		if cap(f.Cache.ValueToProgAfter) < f.NumValues() {
  6578  			f.Cache.ValueToProgAfter = make([]*obj.Prog, f.NumValues())
  6579  		}
  6580  		valueToProgAfter = f.Cache.ValueToProgAfter[:f.NumValues()]
  6581  		clear(valueToProgAfter)
  6582  	}
  6583  
  6584  	// If the very first instruction is not tagged as a statement,
  6585  	// debuggers may attribute it to previous function in program.
  6586  	firstPos := src.NoXPos
  6587  	for _, v := range f.Entry.Values {
  6588  		if v.Pos.IsStmt() == src.PosIsStmt && v.Op != ssa.OpArg && v.Op != ssa.OpArgIntReg && v.Op != ssa.OpArgFloatReg && v.Op != ssa.OpLoadReg && v.Op != ssa.OpStoreReg {
  6589  			firstPos = v.Pos
  6590  			v.Pos = firstPos.WithDefaultStmt()
  6591  			break
  6592  		}
  6593  	}
  6594  
  6595  	// inlMarks has an entry for each Prog that implements an inline mark.
  6596  	// It maps from that Prog to the global inlining id of the inlined body
  6597  	// which should unwind to this Prog's location.
  6598  	var inlMarks map[*obj.Prog]int32
  6599  	var inlMarkList []*obj.Prog
  6600  
  6601  	// inlMarksByPos maps from a (column 1) source position to the set of
  6602  	// Progs that are in the set above and have that source position.
  6603  	var inlMarksByPos map[src.XPos][]*obj.Prog
  6604  
  6605  	var argLiveIdx int = -1 // argument liveness info index
  6606  
  6607  	// These control cache line alignment; if the required portion of
  6608  	// a cache line is not available, then pad to obtain cache line
  6609  	// alignment.  Not implemented on all architectures, may not be
  6610  	// useful on all architectures.
  6611  	var hotAlign, hotRequire int64
  6612  
  6613  	if base.Debug.AlignHot > 0 {
  6614  		switch base.Ctxt.Arch.Name {
  6615  		// enable this on a case-by-case basis, with benchmarking.
  6616  		// currently shown:
  6617  		//   good for amd64
  6618  		//   not helpful for Apple Silicon
  6619  		//
  6620  		case "amd64", "386":
  6621  			// Align to 64 if 31 or fewer bytes remain in a cache line
  6622  			// benchmarks a little better than always aligning, and also
  6623  			// adds slightly less to the (PGO-compiled) binary size.
  6624  			hotAlign = 64
  6625  			hotRequire = 31
  6626  		}
  6627  	}
  6628  
  6629  	// Emit basic blocks
  6630  	for i, b := range f.Blocks {
  6631  
  6632  		s.lineRunStart = nil
  6633  		s.SetPos(s.pp.Pos.WithNotStmt()) // It needs a non-empty Pos, but cannot be a statement boundary (yet).
  6634  
  6635  		if hotAlign > 0 && b.Hotness&ssa.HotPgoInitial == ssa.HotPgoInitial {
  6636  			// So far this has only been shown profitable for PGO-hot loop headers.
  6637  			// The Hotness values allows distinctions between initial blocks that are "hot" or not, and "flow-in" or not.
  6638  			// Currently only the initial blocks of loops are tagged in this way;
  6639  			// there are no blocks tagged "pgo-hot" that are not also tagged "initial".
  6640  			// TODO more heuristics, more architectures.
  6641  			p := s.pp.Prog(obj.APCALIGNMAX)
  6642  			p.From.SetConst(hotAlign)
  6643  			p.To.SetConst(hotRequire)
  6644  		}
  6645  
  6646  		s.bstart[b.ID] = s.pp.Next
  6647  
  6648  		if idx, ok := argLiveBlockMap[b.ID]; ok && idx != argLiveIdx {
  6649  			argLiveIdx = idx
  6650  			p := s.pp.Prog(obj.APCDATA)
  6651  			p.From.SetConst(rtabi.PCDATA_ArgLiveIndex)
  6652  			p.To.SetConst(int64(idx))
  6653  		}
  6654  
  6655  		// Emit values in block
  6656  		Arch.SSAMarkMoves(&s, b)
  6657  		for _, v := range b.Values {
  6658  			x := s.pp.Next
  6659  			s.DebugFriendlySetPosFrom(v)
  6660  
  6661  			if v.Op.ResultInArg0() && v.ResultReg() != v.Args[0].Reg() {
  6662  				v.Fatalf("input[0] and output not in same register %s", v.LongString())
  6663  			}
  6664  
  6665  			switch v.Op {
  6666  			case ssa.OpInitMem:
  6667  				// memory arg needs no code
  6668  			case ssa.OpArg:
  6669  				// input args need no code
  6670  			case ssa.OpSP, ssa.OpSB:
  6671  				// nothing to do
  6672  			case ssa.OpSelect0, ssa.OpSelect1, ssa.OpSelectN, ssa.OpMakeResult:
  6673  				// nothing to do
  6674  			case ssa.OpGetG:
  6675  				// nothing to do when there's a g register,
  6676  				// and checkLower complains if there's not
  6677  			case ssa.OpVarDef, ssa.OpVarLive, ssa.OpKeepAlive, ssa.OpWBend:
  6678  				// nothing to do; already used by liveness
  6679  			case ssa.OpPhi:
  6680  				CheckLoweredPhi(v)
  6681  			case ssa.OpConvert:
  6682  				// nothing to do; no-op conversion for liveness
  6683  				if v.Args[0].Reg() != v.Reg() {
  6684  					v.Fatalf("OpConvert should be a no-op: %s; %s", v.Args[0].LongString(), v.LongString())
  6685  				}
  6686  			case ssa.OpInlMark:
  6687  				p := Arch.Ginsnop(s.pp)
  6688  				if inlMarks == nil {
  6689  					inlMarks = map[*obj.Prog]int32{}
  6690  					inlMarksByPos = map[src.XPos][]*obj.Prog{}
  6691  				}
  6692  				inlMarks[p] = v.AuxInt32()
  6693  				inlMarkList = append(inlMarkList, p)
  6694  				pos := v.Pos.AtColumn1()
  6695  				inlMarksByPos[pos] = append(inlMarksByPos[pos], p)
  6696  				firstPos = src.NoXPos
  6697  
  6698  			default:
  6699  				// Special case for first line in function; move it to the start (which cannot be a register-valued instruction)
  6700  				if firstPos != src.NoXPos && v.Op != ssa.OpArgIntReg && v.Op != ssa.OpArgFloatReg && v.Op != ssa.OpLoadReg && v.Op != ssa.OpStoreReg {
  6701  					s.SetPos(firstPos)
  6702  					firstPos = src.NoXPos
  6703  				}
  6704  				// Attach this safe point to the next
  6705  				// instruction.
  6706  				s.pp.NextLive = s.livenessMap.Get(v)
  6707  				s.pp.NextUnsafe = s.livenessMap.GetUnsafe(v)
  6708  
  6709  				// let the backend handle it
  6710  				Arch.SSAGenValue(&s, v)
  6711  			}
  6712  
  6713  			if idx, ok := argLiveValueMap[v.ID]; ok && idx != argLiveIdx {
  6714  				argLiveIdx = idx
  6715  				p := s.pp.Prog(obj.APCDATA)
  6716  				p.From.SetConst(rtabi.PCDATA_ArgLiveIndex)
  6717  				p.To.SetConst(int64(idx))
  6718  			}
  6719  
  6720  			if base.Ctxt.Flag_locationlists {
  6721  				valueToProgAfter[v.ID] = s.pp.Next
  6722  			}
  6723  
  6724  			if gatherPrintInfo {
  6725  				for ; x != s.pp.Next; x = x.Link {
  6726  					progToValue[x] = v
  6727  				}
  6728  			}
  6729  		}
  6730  		// If this is an empty infinite loop, stick a hardware NOP in there so that debuggers are less confused.
  6731  		if s.bstart[b.ID] == s.pp.Next && len(b.Succs) == 1 && b.Succs[0].Block() == b {
  6732  			p := Arch.Ginsnop(s.pp)
  6733  			p.Pos = p.Pos.WithIsStmt()
  6734  			if b.Pos == src.NoXPos {
  6735  				b.Pos = p.Pos // It needs a file, otherwise a no-file non-zero line causes confusion.  See #35652.
  6736  				if b.Pos == src.NoXPos {
  6737  					b.Pos = s.pp.Text.Pos // Sometimes p.Pos is empty.  See #35695.
  6738  				}
  6739  			}
  6740  			b.Pos = b.Pos.WithBogusLine() // Debuggers are not good about infinite loops, force a change in line number
  6741  		}
  6742  
  6743  		// Set unsafe mark for any end-of-block generated instructions
  6744  		// (normally, conditional or unconditional branches).
  6745  		// This is particularly important for empty blocks, as there
  6746  		// are no values to inherit the unsafe mark from.
  6747  		s.pp.NextUnsafe = s.livenessMap.GetUnsafeBlock(b)
  6748  
  6749  		// Emit control flow instructions for block
  6750  		var next *ssa.Block
  6751  		if i < len(f.Blocks)-1 && base.Flag.N == 0 {
  6752  			// If -N, leave next==nil so every block with successors
  6753  			// ends in a JMP (except call blocks - plive doesn't like
  6754  			// select{send,recv} followed by a JMP call).  Helps keep
  6755  			// line numbers for otherwise empty blocks.
  6756  			next = f.Blocks[i+1]
  6757  		}
  6758  		x := s.pp.Next
  6759  		s.SetPos(b.Pos)
  6760  		Arch.SSAGenBlock(&s, b, next)
  6761  		if gatherPrintInfo {
  6762  			for ; x != s.pp.Next; x = x.Link {
  6763  				progToBlock[x] = b
  6764  			}
  6765  		}
  6766  	}
  6767  	if f.Blocks[len(f.Blocks)-1].Kind == ssa.BlockExit {
  6768  		// We need the return address of a panic call to
  6769  		// still be inside the function in question. So if
  6770  		// it ends in a call which doesn't return, add a
  6771  		// nop (which will never execute) after the call.
  6772  		Arch.Ginsnop(s.pp)
  6773  	}
  6774  	if openDeferInfo != nil {
  6775  		// When doing open-coded defers, generate a disconnected call to
  6776  		// deferreturn and a return. This will be used to during panic
  6777  		// recovery to unwind the stack and return back to the runtime.
  6778  
  6779  		// Note that this exit code doesn't work if a return parameter
  6780  		// is heap-allocated, but open defers aren't enabled in that case.
  6781  
  6782  		// TODO either make this handle heap-allocated return parameters or reuse the other-defers general-purpose code path.
  6783  		s.pp.NextLive = s.livenessMap.DeferReturn
  6784  		p := s.pp.Prog(obj.ACALL)
  6785  		p.To.Type = obj.TYPE_MEM
  6786  		p.To.Name = obj.NAME_EXTERN
  6787  		p.To.Sym = ir.Syms.Deferreturn
  6788  
  6789  		// Load results into registers. So when a deferred function
  6790  		// recovers a panic, it will return to caller with right results.
  6791  		// The results are already in memory, because they are not SSA'd
  6792  		// when the function has defers (see canSSAName).
  6793  		for _, o := range f.OwnAux.ABIInfo().OutParams() {
  6794  			n := o.Name
  6795  			rts, offs := o.RegisterTypesAndOffsets()
  6796  			for i := range o.Registers {
  6797  				Arch.LoadRegResult(&s, f, rts[i], ssa.ObjRegForAbiReg(o.Registers[i], f.Config), n, offs[i])
  6798  			}
  6799  		}
  6800  
  6801  		s.pp.Prog(obj.ARET)
  6802  	}
  6803  
  6804  	if inlMarks != nil {
  6805  		hasCall := false
  6806  
  6807  		// We have some inline marks. Try to find other instructions we're
  6808  		// going to emit anyway, and use those instructions instead of the
  6809  		// inline marks.
  6810  		for p := s.pp.Text; p != nil; p = p.Link {
  6811  			if p.As == obj.ANOP || p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT ||
  6812  				p.As == obj.APCALIGN || p.As == obj.APCALIGNMAX || Arch.LinkArch.Family == sys.Wasm {
  6813  				// Don't use 0-sized instructions as inline marks, because we need
  6814  				// to identify inline mark instructions by pc offset.
  6815  				// (Some of these instructions are sometimes zero-sized, sometimes not.
  6816  				// We must not use anything that even might be zero-sized.)
  6817  				// TODO: are there others?
  6818  				continue
  6819  			}
  6820  			if _, ok := inlMarks[p]; ok {
  6821  				// Don't use inline marks themselves. We don't know
  6822  				// whether they will be zero-sized or not yet.
  6823  				continue
  6824  			}
  6825  			if p.As == obj.ACALL || p.As == obj.ADUFFCOPY || p.As == obj.ADUFFZERO {
  6826  				hasCall = true
  6827  			}
  6828  			pos := p.Pos.AtColumn1()
  6829  			marks := inlMarksByPos[pos]
  6830  			if len(marks) == 0 {
  6831  				continue
  6832  			}
  6833  			for _, m := range marks {
  6834  				// We found an instruction with the same source position as
  6835  				// some of the inline marks.
  6836  				// Use this instruction instead.
  6837  				p.Pos = p.Pos.WithIsStmt() // promote position to a statement
  6838  				s.pp.CurFunc.LSym.Func().AddInlMark(p, inlMarks[m])
  6839  				// Make the inline mark a real nop, so it doesn't generate any code.
  6840  				m.As = obj.ANOP
  6841  				m.Pos = src.NoXPos
  6842  				m.From = obj.Addr{}
  6843  				m.To = obj.Addr{}
  6844  			}
  6845  			delete(inlMarksByPos, pos)
  6846  		}
  6847  		// Any unmatched inline marks now need to be added to the inlining tree (and will generate a nop instruction).
  6848  		for _, p := range inlMarkList {
  6849  			if p.As != obj.ANOP {
  6850  				s.pp.CurFunc.LSym.Func().AddInlMark(p, inlMarks[p])
  6851  			}
  6852  		}
  6853  
  6854  		if e.stksize == 0 && !hasCall {
  6855  			// Frameless leaf function. It doesn't need any preamble,
  6856  			// so make sure its first instruction isn't from an inlined callee.
  6857  			// If it is, add a nop at the start of the function with a position
  6858  			// equal to the start of the function.
  6859  			// This ensures that runtime.FuncForPC(uintptr(reflect.ValueOf(fn).Pointer())).Name()
  6860  			// returns the right answer. See issue 58300.
  6861  			for p := s.pp.Text; p != nil; p = p.Link {
  6862  				if p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT || p.As == obj.ANOP {
  6863  					continue
  6864  				}
  6865  				if base.Ctxt.PosTable.Pos(p.Pos).Base().InliningIndex() >= 0 {
  6866  					// Make a real (not 0-sized) nop.
  6867  					nop := Arch.Ginsnop(s.pp)
  6868  					nop.Pos = e.curfn.Pos().WithIsStmt()
  6869  
  6870  					// Unfortunately, Ginsnop puts the instruction at the
  6871  					// end of the list. Move it up to just before p.
  6872  
  6873  					// Unlink from the current list.
  6874  					for x := s.pp.Text; x != nil; x = x.Link {
  6875  						if x.Link == nop {
  6876  							x.Link = nop.Link
  6877  							break
  6878  						}
  6879  					}
  6880  					// Splice in right before p.
  6881  					for x := s.pp.Text; x != nil; x = x.Link {
  6882  						if x.Link == p {
  6883  							nop.Link = p
  6884  							x.Link = nop
  6885  							break
  6886  						}
  6887  					}
  6888  				}
  6889  				break
  6890  			}
  6891  		}
  6892  	}
  6893  
  6894  	if base.Ctxt.Flag_locationlists {
  6895  		var debugInfo *ssa.FuncDebug
  6896  		debugInfo = e.curfn.DebugInfo.(*ssa.FuncDebug)
  6897  		// Save off entry ID in case we need it later for DWARF generation
  6898  		// for return values promoted to the heap.
  6899  		debugInfo.EntryID = f.Entry.ID
  6900  		if e.curfn.ABI == obj.ABIInternal && base.Flag.N != 0 {
  6901  			ssa.BuildFuncDebugNoOptimized(base.Ctxt, f, base.Debug.LocationLists > 1, StackOffset, debugInfo)
  6902  		} else {
  6903  			ssa.BuildFuncDebug(base.Ctxt, f, base.Debug.LocationLists, StackOffset, debugInfo)
  6904  		}
  6905  		bstart := s.bstart
  6906  		idToIdx := make([]int, f.NumBlocks())
  6907  		for i, b := range f.Blocks {
  6908  			idToIdx[b.ID] = i
  6909  		}
  6910  		// Register a callback that will be used later to fill in PCs into location
  6911  		// lists. At the moment, Prog.Pc is a sequence number; it's not a real PC
  6912  		// until after assembly, so the translation needs to be deferred.
  6913  		debugInfo.GetPC = func(b, v ssa.ID) int64 {
  6914  			switch v {
  6915  			case ssa.BlockStart.ID:
  6916  				if b == f.Entry.ID {
  6917  					return 0 // Start at the very beginning, at the assembler-generated prologue.
  6918  					// this should only happen for function args (ssa.OpArg)
  6919  				}
  6920  				return bstart[b].Pc
  6921  			case ssa.BlockEnd.ID:
  6922  				blk := f.Blocks[idToIdx[b]]
  6923  				nv := len(blk.Values)
  6924  				return valueToProgAfter[blk.Values[nv-1].ID].Pc
  6925  			case ssa.FuncEnd.ID:
  6926  				return e.curfn.LSym.Size
  6927  			default:
  6928  				return valueToProgAfter[v].Pc
  6929  			}
  6930  		}
  6931  	}
  6932  
  6933  	// Resolve branches, and relax DefaultStmt into NotStmt
  6934  	for _, br := range s.Branches {
  6935  		br.P.To.SetTarget(s.bstart[br.B.ID])
  6936  		if br.P.Pos.IsStmt() != src.PosIsStmt {
  6937  			br.P.Pos = br.P.Pos.WithNotStmt()
  6938  		} else if v0 := br.B.FirstPossibleStmtValue(); v0 != nil && v0.Pos.Line() == br.P.Pos.Line() && v0.Pos.IsStmt() == src.PosIsStmt {
  6939  			br.P.Pos = br.P.Pos.WithNotStmt()
  6940  		}
  6941  
  6942  	}
  6943  
  6944  	// Resolve jump table destinations.
  6945  	for _, jt := range s.JumpTables {
  6946  		// Convert from *Block targets to *Prog targets.
  6947  		targets := make([]*obj.Prog, len(jt.Succs))
  6948  		for i, e := range jt.Succs {
  6949  			targets[i] = s.bstart[e.Block().ID]
  6950  		}
  6951  		// Add to list of jump tables to be resolved at assembly time.
  6952  		// The assembler converts from *Prog entries to absolute addresses
  6953  		// once it knows instruction byte offsets.
  6954  		fi := s.pp.CurFunc.LSym.Func()
  6955  		fi.JumpTables = append(fi.JumpTables, obj.JumpTable{Sym: jt.Aux.(*obj.LSym), Targets: targets})
  6956  	}
  6957  
  6958  	if e.log { // spew to stdout
  6959  		filename := ""
  6960  		for p := s.pp.Text; p != nil; p = p.Link {
  6961  			if p.Pos.IsKnown() && p.InnermostFilename() != filename {
  6962  				filename = p.InnermostFilename()
  6963  				f.Logf("# %s\n", filename)
  6964  			}
  6965  
  6966  			var s string
  6967  			if v, ok := progToValue[p]; ok {
  6968  				s = v.String()
  6969  			} else if b, ok := progToBlock[p]; ok {
  6970  				s = b.String()
  6971  			} else {
  6972  				s = "   " // most value and branch strings are 2-3 characters long
  6973  			}
  6974  			f.Logf(" %-6s\t%.5d (%s)\t%s\n", s, p.Pc, p.InnermostLineNumber(), p.InstructionString())
  6975  		}
  6976  	}
  6977  	if f.HTMLWriter != nil { // spew to ssa.html
  6978  		var buf strings.Builder
  6979  		buf.WriteString("<code>")
  6980  		buf.WriteString("<dl class=\"ssa-gen\">")
  6981  		filename := ""
  6982  
  6983  		liveness := lv.Format(nil)
  6984  		if liveness != "" {
  6985  			buf.WriteString("<dt class=\"ssa-prog-src\"></dt><dd class=\"ssa-prog\">")
  6986  			buf.WriteString(html.EscapeString("# " + liveness))
  6987  			buf.WriteString("</dd>")
  6988  		}
  6989  
  6990  		for p := s.pp.Text; p != nil; p = p.Link {
  6991  			// Don't spam every line with the file name, which is often huge.
  6992  			// Only print changes, and "unknown" is not a change.
  6993  			if p.Pos.IsKnown() && p.InnermostFilename() != filename {
  6994  				filename = p.InnermostFilename()
  6995  				buf.WriteString("<dt class=\"ssa-prog-src\"></dt><dd class=\"ssa-prog\">")
  6996  				buf.WriteString(html.EscapeString("# " + filename))
  6997  				buf.WriteString("</dd>")
  6998  			}
  6999  
  7000  			buf.WriteString("<dt class=\"ssa-prog-src\">")
  7001  			if v, ok := progToValue[p]; ok {
  7002  
  7003  				// Prefix calls with their liveness, if any
  7004  				if p.As != obj.APCDATA {
  7005  					if liveness := lv.Format(v); liveness != "" {
  7006  						// Steal this line, and restart a line
  7007  						buf.WriteString("</dt><dd class=\"ssa-prog\">")
  7008  						buf.WriteString(html.EscapeString("# " + liveness))
  7009  						buf.WriteString("</dd>")
  7010  						// restarting a line
  7011  						buf.WriteString("<dt class=\"ssa-prog-src\">")
  7012  					}
  7013  				}
  7014  
  7015  				buf.WriteString(v.HTML())
  7016  			} else if b, ok := progToBlock[p]; ok {
  7017  				buf.WriteString("<b>" + b.HTML() + "</b>")
  7018  			}
  7019  			buf.WriteString("</dt>")
  7020  			buf.WriteString("<dd class=\"ssa-prog\">")
  7021  			fmt.Fprintf(&buf, "%.5d <span class=\"l%v line-number\">(%s)</span> %s", p.Pc, p.InnermostLineNumber(), p.InnermostLineNumberHTML(), html.EscapeString(p.InstructionString()))
  7022  			buf.WriteString("</dd>")
  7023  		}
  7024  		buf.WriteString("</dl>")
  7025  		buf.WriteString("</code>")
  7026  		f.HTMLWriter.WriteColumn("genssa", "genssa", "ssa-prog", buf.String())
  7027  	}
  7028  	if ssa.GenssaDump[f.Name] {
  7029  		fi := f.DumpFileForPhase("genssa")
  7030  		if fi != nil {
  7031  
  7032  			// inliningDiffers if any filename changes or if any line number except the innermost (last index) changes.
  7033  			inliningDiffers := func(a, b []src.Pos) bool {
  7034  				if len(a) != len(b) {
  7035  					return true
  7036  				}
  7037  				for i := range a {
  7038  					if a[i].Filename() != b[i].Filename() {
  7039  						return true
  7040  					}
  7041  					if i != len(a)-1 && a[i].Line() != b[i].Line() {
  7042  						return true
  7043  					}
  7044  				}
  7045  				return false
  7046  			}
  7047  
  7048  			var allPosOld []src.Pos
  7049  			var allPos []src.Pos
  7050  
  7051  			for p := s.pp.Text; p != nil; p = p.Link {
  7052  				if p.Pos.IsKnown() {
  7053  					allPos = allPos[:0]
  7054  					p.Ctxt.AllPos(p.Pos, func(pos src.Pos) { allPos = append(allPos, pos) })
  7055  					if inliningDiffers(allPos, allPosOld) {
  7056  						for _, pos := range allPos {
  7057  							fmt.Fprintf(fi, "# %s:%d\n", pos.Filename(), pos.Line())
  7058  						}
  7059  						allPos, allPosOld = allPosOld, allPos // swap, not copy, so that they do not share slice storage.
  7060  					}
  7061  				}
  7062  
  7063  				var s string
  7064  				if v, ok := progToValue[p]; ok {
  7065  					s = v.String()
  7066  				} else if b, ok := progToBlock[p]; ok {
  7067  					s = b.String()
  7068  				} else {
  7069  					s = "   " // most value and branch strings are 2-3 characters long
  7070  				}
  7071  				fmt.Fprintf(fi, " %-6s\t%.5d %s\t%s\n", s, p.Pc, ssa.StmtString(p.Pos), p.InstructionString())
  7072  			}
  7073  			fi.Close()
  7074  		}
  7075  	}
  7076  
  7077  	defframe(&s, e, f)
  7078  
  7079  	f.HTMLWriter.Close()
  7080  	f.HTMLWriter = nil
  7081  }
  7082  
  7083  func defframe(s *State, e *ssafn, f *ssa.Func) {
  7084  	pp := s.pp
  7085  
  7086  	s.maxarg = types.RoundUp(s.maxarg, e.stkalign)
  7087  	frame := s.maxarg + e.stksize
  7088  	if Arch.PadFrame != nil {
  7089  		frame = Arch.PadFrame(frame)
  7090  	}
  7091  
  7092  	// Fill in argument and frame size.
  7093  	pp.Text.To.Type = obj.TYPE_TEXTSIZE
  7094  	pp.Text.To.Val = int32(types.RoundUp(f.OwnAux.ArgWidth(), int64(types.RegSize)))
  7095  	pp.Text.To.Offset = frame
  7096  
  7097  	p := pp.Text
  7098  
  7099  	// Insert code to spill argument registers if the named slot may be partially
  7100  	// live. That is, the named slot is considered live by liveness analysis,
  7101  	// (because a part of it is live), but we may not spill all parts into the
  7102  	// slot. This can only happen with aggregate-typed arguments that are SSA-able
  7103  	// and not address-taken (for non-SSA-able or address-taken arguments we always
  7104  	// spill upfront).
  7105  	// Note: spilling is unnecessary in the -N/no-optimize case, since all values
  7106  	// will be considered non-SSAable and spilled up front.
  7107  	// TODO(register args) Make liveness more fine-grained to that partial spilling is okay.
  7108  	if f.OwnAux.ABIInfo().InRegistersUsed() != 0 && base.Flag.N == 0 {
  7109  		// First, see if it is already spilled before it may be live. Look for a spill
  7110  		// in the entry block up to the first safepoint.
  7111  		type nameOff struct {
  7112  			n   *ir.Name
  7113  			off int64
  7114  		}
  7115  		partLiveArgsSpilled := make(map[nameOff]bool)
  7116  		for _, v := range f.Entry.Values {
  7117  			if v.Op.IsCall() {
  7118  				break
  7119  			}
  7120  			if v.Op != ssa.OpStoreReg || v.Args[0].Op != ssa.OpArgIntReg {
  7121  				continue
  7122  			}
  7123  			n, off := ssa.AutoVar(v)
  7124  			if n.Class != ir.PPARAM || n.Addrtaken() || !ssa.CanSSA(n.Type()) || !s.partLiveArgs[n] {
  7125  				continue
  7126  			}
  7127  			partLiveArgsSpilled[nameOff{n, off}] = true
  7128  		}
  7129  
  7130  		// Then, insert code to spill registers if not already.
  7131  		for _, a := range f.OwnAux.ABIInfo().InParams() {
  7132  			n := a.Name
  7133  			if n == nil || n.Addrtaken() || !ssa.CanSSA(n.Type()) || !s.partLiveArgs[n] || len(a.Registers) <= 1 {
  7134  				continue
  7135  			}
  7136  			rts, offs := a.RegisterTypesAndOffsets()
  7137  			for i := range a.Registers {
  7138  				if !rts[i].HasPointers() {
  7139  					continue
  7140  				}
  7141  				if partLiveArgsSpilled[nameOff{n, offs[i]}] {
  7142  					continue // already spilled
  7143  				}
  7144  				reg := ssa.ObjRegForAbiReg(a.Registers[i], f.Config)
  7145  				p = Arch.SpillArgReg(pp, p, f, rts[i], reg, n, offs[i])
  7146  			}
  7147  		}
  7148  	}
  7149  
  7150  	// Insert code to zero ambiguously live variables so that the
  7151  	// garbage collector only sees initialized values when it
  7152  	// looks for pointers.
  7153  	var lo, hi int64
  7154  
  7155  	// Opaque state for backend to use. Current backends use it to
  7156  	// keep track of which helper registers have been zeroed.
  7157  	var state uint32
  7158  
  7159  	// Iterate through declarations. Autos are sorted in decreasing
  7160  	// frame offset order.
  7161  	for _, n := range e.curfn.Dcl {
  7162  		if !n.Needzero() {
  7163  			continue
  7164  		}
  7165  		if n.Class != ir.PAUTO {
  7166  			e.Fatalf(n.Pos(), "needzero class %d", n.Class)
  7167  		}
  7168  		if n.Type().Size()%int64(types.PtrSize) != 0 || n.FrameOffset()%int64(types.PtrSize) != 0 || n.Type().Size() == 0 {
  7169  			e.Fatalf(n.Pos(), "var %L has size %d offset %d", n, n.Type().Size(), n.Offset_)
  7170  		}
  7171  
  7172  		if lo != hi && n.FrameOffset()+n.Type().Size() >= lo-int64(2*types.RegSize) {
  7173  			// Merge with range we already have.
  7174  			lo = n.FrameOffset()
  7175  			continue
  7176  		}
  7177  
  7178  		// Zero old range
  7179  		p = Arch.ZeroRange(pp, p, frame+lo, hi-lo, &state)
  7180  
  7181  		// Set new range.
  7182  		lo = n.FrameOffset()
  7183  		hi = lo + n.Type().Size()
  7184  	}
  7185  
  7186  	// Zero final range.
  7187  	Arch.ZeroRange(pp, p, frame+lo, hi-lo, &state)
  7188  }
  7189  
  7190  // For generating consecutive jump instructions to model a specific branching
  7191  type IndexJump struct {
  7192  	Jump  obj.As
  7193  	Index int
  7194  }
  7195  
  7196  func (s *State) oneJump(b *ssa.Block, jump *IndexJump) {
  7197  	p := s.Br(jump.Jump, b.Succs[jump.Index].Block())
  7198  	p.Pos = b.Pos
  7199  }
  7200  
  7201  // CombJump generates combinational instructions (2 at present) for a block jump,
  7202  // thereby the behaviour of non-standard condition codes could be simulated
  7203  func (s *State) CombJump(b, next *ssa.Block, jumps *[2][2]IndexJump) {
  7204  	switch next {
  7205  	case b.Succs[0].Block():
  7206  		s.oneJump(b, &jumps[0][0])
  7207  		s.oneJump(b, &jumps[0][1])
  7208  	case b.Succs[1].Block():
  7209  		s.oneJump(b, &jumps[1][0])
  7210  		s.oneJump(b, &jumps[1][1])
  7211  	default:
  7212  		var q *obj.Prog
  7213  		if b.Likely != ssa.BranchUnlikely {
  7214  			s.oneJump(b, &jumps[1][0])
  7215  			s.oneJump(b, &jumps[1][1])
  7216  			q = s.Br(obj.AJMP, b.Succs[1].Block())
  7217  		} else {
  7218  			s.oneJump(b, &jumps[0][0])
  7219  			s.oneJump(b, &jumps[0][1])
  7220  			q = s.Br(obj.AJMP, b.Succs[0].Block())
  7221  		}
  7222  		q.Pos = b.Pos
  7223  	}
  7224  }
  7225  
  7226  // AddAux adds the offset in the aux fields (AuxInt and Aux) of v to a.
  7227  func AddAux(a *obj.Addr, v *ssa.Value) {
  7228  	AddAux2(a, v, v.AuxInt)
  7229  }
  7230  func AddAux2(a *obj.Addr, v *ssa.Value, offset int64) {
  7231  	if a.Type != obj.TYPE_MEM && a.Type != obj.TYPE_ADDR {
  7232  		v.Fatalf("bad AddAux addr %v", a)
  7233  	}
  7234  	// add integer offset
  7235  	a.Offset += offset
  7236  
  7237  	// If no additional symbol offset, we're done.
  7238  	if v.Aux == nil {
  7239  		return
  7240  	}
  7241  	// Add symbol's offset from its base register.
  7242  	switch n := v.Aux.(type) {
  7243  	case *ssa.AuxCall:
  7244  		a.Name = obj.NAME_EXTERN
  7245  		a.Sym = n.Fn
  7246  	case *obj.LSym:
  7247  		a.Name = obj.NAME_EXTERN
  7248  		a.Sym = n
  7249  	case *ir.Name:
  7250  		if n.Class == ir.PPARAM || (n.Class == ir.PPARAMOUT && !n.IsOutputParamInRegisters()) {
  7251  			a.Name = obj.NAME_PARAM
  7252  		} else {
  7253  			a.Name = obj.NAME_AUTO
  7254  		}
  7255  		a.Sym = n.Linksym()
  7256  		a.Offset += n.FrameOffset()
  7257  	default:
  7258  		v.Fatalf("aux in %s not implemented %#v", v, v.Aux)
  7259  	}
  7260  }
  7261  
  7262  // extendIndex extends v to a full int width.
  7263  // panic with the given kind if v does not fit in an int (only on 32-bit archs).
  7264  func (s *state) extendIndex(idx, len *ssa.Value, kind ssa.BoundsKind, bounded bool) *ssa.Value {
  7265  	size := idx.Type.Size()
  7266  	if size == s.config.PtrSize {
  7267  		return idx
  7268  	}
  7269  	if size > s.config.PtrSize {
  7270  		// truncate 64-bit indexes on 32-bit pointer archs. Test the
  7271  		// high word and branch to out-of-bounds failure if it is not 0.
  7272  		var lo *ssa.Value
  7273  		if idx.Type.IsSigned() {
  7274  			lo = s.newValue1(ssa.OpInt64Lo, types.Types[types.TINT], idx)
  7275  		} else {
  7276  			lo = s.newValue1(ssa.OpInt64Lo, types.Types[types.TUINT], idx)
  7277  		}
  7278  		if bounded || base.Flag.B != 0 {
  7279  			return lo
  7280  		}
  7281  		bNext := s.f.NewBlock(ssa.BlockPlain)
  7282  		bPanic := s.f.NewBlock(ssa.BlockExit)
  7283  		hi := s.newValue1(ssa.OpInt64Hi, types.Types[types.TUINT32], idx)
  7284  		cmp := s.newValue2(ssa.OpEq32, types.Types[types.TBOOL], hi, s.constInt32(types.Types[types.TUINT32], 0))
  7285  		if !idx.Type.IsSigned() {
  7286  			switch kind {
  7287  			case ssa.BoundsIndex:
  7288  				kind = ssa.BoundsIndexU
  7289  			case ssa.BoundsSliceAlen:
  7290  				kind = ssa.BoundsSliceAlenU
  7291  			case ssa.BoundsSliceAcap:
  7292  				kind = ssa.BoundsSliceAcapU
  7293  			case ssa.BoundsSliceB:
  7294  				kind = ssa.BoundsSliceBU
  7295  			case ssa.BoundsSlice3Alen:
  7296  				kind = ssa.BoundsSlice3AlenU
  7297  			case ssa.BoundsSlice3Acap:
  7298  				kind = ssa.BoundsSlice3AcapU
  7299  			case ssa.BoundsSlice3B:
  7300  				kind = ssa.BoundsSlice3BU
  7301  			case ssa.BoundsSlice3C:
  7302  				kind = ssa.BoundsSlice3CU
  7303  			}
  7304  		}
  7305  		b := s.endBlock()
  7306  		b.Kind = ssa.BlockIf
  7307  		b.SetControl(cmp)
  7308  		b.Likely = ssa.BranchLikely
  7309  		b.AddEdgeTo(bNext)
  7310  		b.AddEdgeTo(bPanic)
  7311  
  7312  		s.startBlock(bPanic)
  7313  		mem := s.newValue4I(ssa.OpPanicExtend, types.TypeMem, int64(kind), hi, lo, len, s.mem())
  7314  		s.endBlock().SetControl(mem)
  7315  		s.startBlock(bNext)
  7316  
  7317  		return lo
  7318  	}
  7319  
  7320  	// Extend value to the required size
  7321  	var op ssa.Op
  7322  	if idx.Type.IsSigned() {
  7323  		switch 10*size + s.config.PtrSize {
  7324  		case 14:
  7325  			op = ssa.OpSignExt8to32
  7326  		case 18:
  7327  			op = ssa.OpSignExt8to64
  7328  		case 24:
  7329  			op = ssa.OpSignExt16to32
  7330  		case 28:
  7331  			op = ssa.OpSignExt16to64
  7332  		case 48:
  7333  			op = ssa.OpSignExt32to64
  7334  		default:
  7335  			s.Fatalf("bad signed index extension %s", idx.Type)
  7336  		}
  7337  	} else {
  7338  		switch 10*size + s.config.PtrSize {
  7339  		case 14:
  7340  			op = ssa.OpZeroExt8to32
  7341  		case 18:
  7342  			op = ssa.OpZeroExt8to64
  7343  		case 24:
  7344  			op = ssa.OpZeroExt16to32
  7345  		case 28:
  7346  			op = ssa.OpZeroExt16to64
  7347  		case 48:
  7348  			op = ssa.OpZeroExt32to64
  7349  		default:
  7350  			s.Fatalf("bad unsigned index extension %s", idx.Type)
  7351  		}
  7352  	}
  7353  	return s.newValue1(op, types.Types[types.TINT], idx)
  7354  }
  7355  
  7356  // CheckLoweredPhi checks that regalloc and stackalloc correctly handled phi values.
  7357  // Called during ssaGenValue.
  7358  func CheckLoweredPhi(v *ssa.Value) {
  7359  	if v.Op != ssa.OpPhi {
  7360  		v.Fatalf("CheckLoweredPhi called with non-phi value: %v", v.LongString())
  7361  	}
  7362  	if v.Type.IsMemory() {
  7363  		return
  7364  	}
  7365  	f := v.Block.Func
  7366  	loc := f.RegAlloc[v.ID]
  7367  	for _, a := range v.Args {
  7368  		if aloc := f.RegAlloc[a.ID]; aloc != loc { // TODO: .Equal() instead?
  7369  			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)
  7370  		}
  7371  	}
  7372  }
  7373  
  7374  // CheckLoweredGetClosurePtr checks that v is the first instruction in the function's entry block,
  7375  // except for incoming in-register arguments.
  7376  // The output of LoweredGetClosurePtr is generally hardwired to the correct register.
  7377  // That register contains the closure pointer on closure entry.
  7378  func CheckLoweredGetClosurePtr(v *ssa.Value) {
  7379  	entry := v.Block.Func.Entry
  7380  	if entry != v.Block {
  7381  		base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
  7382  	}
  7383  	for _, w := range entry.Values {
  7384  		if w == v {
  7385  			break
  7386  		}
  7387  		switch w.Op {
  7388  		case ssa.OpArgIntReg, ssa.OpArgFloatReg:
  7389  			// okay
  7390  		default:
  7391  			base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
  7392  		}
  7393  	}
  7394  }
  7395  
  7396  // CheckArgReg ensures that v is in the function's entry block.
  7397  func CheckArgReg(v *ssa.Value) {
  7398  	entry := v.Block.Func.Entry
  7399  	if entry != v.Block {
  7400  		base.Fatalf("in %s, badly placed ArgIReg or ArgFReg: %v %v", v.Block.Func.Name, v.Block, v)
  7401  	}
  7402  }
  7403  
  7404  func AddrAuto(a *obj.Addr, v *ssa.Value) {
  7405  	n, off := ssa.AutoVar(v)
  7406  	a.Type = obj.TYPE_MEM
  7407  	a.Sym = n.Linksym()
  7408  	a.Reg = int16(Arch.REGSP)
  7409  	a.Offset = n.FrameOffset() + off
  7410  	if n.Class == ir.PPARAM || (n.Class == ir.PPARAMOUT && !n.IsOutputParamInRegisters()) {
  7411  		a.Name = obj.NAME_PARAM
  7412  	} else {
  7413  		a.Name = obj.NAME_AUTO
  7414  	}
  7415  }
  7416  
  7417  // Call returns a new CALL instruction for the SSA value v.
  7418  // It uses PrepareCall to prepare the call.
  7419  func (s *State) Call(v *ssa.Value) *obj.Prog {
  7420  	pPosIsStmt := s.pp.Pos.IsStmt() // The statement-ness fo the call comes from ssaGenState
  7421  	s.PrepareCall(v)
  7422  
  7423  	p := s.Prog(obj.ACALL)
  7424  	if pPosIsStmt == src.PosIsStmt {
  7425  		p.Pos = v.Pos.WithIsStmt()
  7426  	} else {
  7427  		p.Pos = v.Pos.WithNotStmt()
  7428  	}
  7429  	if sym, ok := v.Aux.(*ssa.AuxCall); ok && sym.Fn != nil {
  7430  		p.To.Type = obj.TYPE_MEM
  7431  		p.To.Name = obj.NAME_EXTERN
  7432  		p.To.Sym = sym.Fn
  7433  	} else {
  7434  		// TODO(mdempsky): Can these differences be eliminated?
  7435  		switch Arch.LinkArch.Family {
  7436  		case sys.AMD64, sys.I386, sys.PPC64, sys.RISCV64, sys.S390X, sys.Wasm:
  7437  			p.To.Type = obj.TYPE_REG
  7438  		case sys.ARM, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64:
  7439  			p.To.Type = obj.TYPE_MEM
  7440  		default:
  7441  			base.Fatalf("unknown indirect call family")
  7442  		}
  7443  		p.To.Reg = v.Args[0].Reg()
  7444  	}
  7445  	return p
  7446  }
  7447  
  7448  // TailCall returns a new tail call instruction for the SSA value v.
  7449  // It is like Call, but for a tail call.
  7450  func (s *State) TailCall(v *ssa.Value) *obj.Prog {
  7451  	p := s.Call(v)
  7452  	p.As = obj.ARET
  7453  	return p
  7454  }
  7455  
  7456  // PrepareCall prepares to emit a CALL instruction for v and does call-related bookkeeping.
  7457  // It must be called immediately before emitting the actual CALL instruction,
  7458  // since it emits PCDATA for the stack map at the call (calls are safe points).
  7459  func (s *State) PrepareCall(v *ssa.Value) {
  7460  	idx := s.livenessMap.Get(v)
  7461  	if !idx.StackMapValid() {
  7462  		// See Liveness.hasStackMap.
  7463  		if sym, ok := v.Aux.(*ssa.AuxCall); !ok || !(sym.Fn == ir.Syms.WBZero || sym.Fn == ir.Syms.WBMove) {
  7464  			base.Fatalf("missing stack map index for %v", v.LongString())
  7465  		}
  7466  	}
  7467  
  7468  	call, ok := v.Aux.(*ssa.AuxCall)
  7469  
  7470  	if ok {
  7471  		// Record call graph information for nowritebarrierrec
  7472  		// analysis.
  7473  		if nowritebarrierrecCheck != nil {
  7474  			nowritebarrierrecCheck.recordCall(s.pp.CurFunc, call.Fn, v.Pos)
  7475  		}
  7476  	}
  7477  
  7478  	if s.maxarg < v.AuxInt {
  7479  		s.maxarg = v.AuxInt
  7480  	}
  7481  }
  7482  
  7483  // UseArgs records the fact that an instruction needs a certain amount of
  7484  // callee args space for its use.
  7485  func (s *State) UseArgs(n int64) {
  7486  	if s.maxarg < n {
  7487  		s.maxarg = n
  7488  	}
  7489  }
  7490  
  7491  // fieldIdx finds the index of the field referred to by the ODOT node n.
  7492  func fieldIdx(n *ir.SelectorExpr) int {
  7493  	t := n.X.Type()
  7494  	if !t.IsStruct() {
  7495  		panic("ODOT's LHS is not a struct")
  7496  	}
  7497  
  7498  	for i, f := range t.Fields() {
  7499  		if f.Sym == n.Sel {
  7500  			if f.Offset != n.Offset() {
  7501  				panic("field offset doesn't match")
  7502  			}
  7503  			return i
  7504  		}
  7505  	}
  7506  	panic(fmt.Sprintf("can't find field in expr %v\n", n))
  7507  
  7508  	// TODO: keep the result of this function somewhere in the ODOT Node
  7509  	// so we don't have to recompute it each time we need it.
  7510  }
  7511  
  7512  // ssafn holds frontend information about a function that the backend is processing.
  7513  // It also exports a bunch of compiler services for the ssa backend.
  7514  type ssafn struct {
  7515  	curfn      *ir.Func
  7516  	strings    map[string]*obj.LSym // map from constant string to data symbols
  7517  	stksize    int64                // stack size for current frame
  7518  	stkptrsize int64                // prefix of stack containing pointers
  7519  
  7520  	// alignment for current frame.
  7521  	// NOTE: when stkalign > PtrSize, currently this only ensures the offsets of
  7522  	// objects in the stack frame are aligned. The stack pointer is still aligned
  7523  	// only PtrSize.
  7524  	stkalign int64
  7525  
  7526  	log bool // print ssa debug to the stdout
  7527  }
  7528  
  7529  // StringData returns a symbol which
  7530  // is the data component of a global string constant containing s.
  7531  func (e *ssafn) StringData(s string) *obj.LSym {
  7532  	if aux, ok := e.strings[s]; ok {
  7533  		return aux
  7534  	}
  7535  	if e.strings == nil {
  7536  		e.strings = make(map[string]*obj.LSym)
  7537  	}
  7538  	data := staticdata.StringSym(e.curfn.Pos(), s)
  7539  	e.strings[s] = data
  7540  	return data
  7541  }
  7542  
  7543  // SplitSlot returns a slot representing the data of parent starting at offset.
  7544  func (e *ssafn) SplitSlot(parent *ssa.LocalSlot, suffix string, offset int64, t *types.Type) ssa.LocalSlot {
  7545  	node := parent.N
  7546  
  7547  	if node.Class != ir.PAUTO || node.Addrtaken() {
  7548  		// addressed things and non-autos retain their parents (i.e., cannot truly be split)
  7549  		return ssa.LocalSlot{N: node, Type: t, Off: parent.Off + offset}
  7550  	}
  7551  
  7552  	sym := &types.Sym{Name: node.Sym().Name + suffix, Pkg: types.LocalPkg}
  7553  	n := e.curfn.NewLocal(parent.N.Pos(), sym, t)
  7554  	n.SetUsed(true)
  7555  	n.SetEsc(ir.EscNever)
  7556  	types.CalcSize(t)
  7557  	return ssa.LocalSlot{N: n, Type: t, Off: 0, SplitOf: parent, SplitOffset: offset}
  7558  }
  7559  
  7560  // Logf logs a message from the compiler.
  7561  func (e *ssafn) Logf(msg string, args ...interface{}) {
  7562  	if e.log {
  7563  		fmt.Printf(msg, args...)
  7564  	}
  7565  }
  7566  
  7567  func (e *ssafn) Log() bool {
  7568  	return e.log
  7569  }
  7570  
  7571  // Fatalf reports a compiler error and exits.
  7572  func (e *ssafn) Fatalf(pos src.XPos, msg string, args ...interface{}) {
  7573  	base.Pos = pos
  7574  	nargs := append([]interface{}{ir.FuncName(e.curfn)}, args...)
  7575  	base.Fatalf("'%s': "+msg, nargs...)
  7576  }
  7577  
  7578  // Warnl reports a "warning", which is usually flag-triggered
  7579  // logging output for the benefit of tests.
  7580  func (e *ssafn) Warnl(pos src.XPos, fmt_ string, args ...interface{}) {
  7581  	base.WarnfAt(pos, fmt_, args...)
  7582  }
  7583  
  7584  func (e *ssafn) Debug_checknil() bool {
  7585  	return base.Debug.Nil != 0
  7586  }
  7587  
  7588  func (e *ssafn) UseWriteBarrier() bool {
  7589  	return base.Flag.WB
  7590  }
  7591  
  7592  func (e *ssafn) Syslook(name string) *obj.LSym {
  7593  	switch name {
  7594  	case "goschedguarded":
  7595  		return ir.Syms.Goschedguarded
  7596  	case "writeBarrier":
  7597  		return ir.Syms.WriteBarrier
  7598  	case "wbZero":
  7599  		return ir.Syms.WBZero
  7600  	case "wbMove":
  7601  		return ir.Syms.WBMove
  7602  	case "cgoCheckMemmove":
  7603  		return ir.Syms.CgoCheckMemmove
  7604  	case "cgoCheckPtrWrite":
  7605  		return ir.Syms.CgoCheckPtrWrite
  7606  	}
  7607  	e.Fatalf(src.NoXPos, "unknown Syslook func %v", name)
  7608  	return nil
  7609  }
  7610  
  7611  func (e *ssafn) Func() *ir.Func {
  7612  	return e.curfn
  7613  }
  7614  
  7615  func clobberBase(n ir.Node) ir.Node {
  7616  	if n.Op() == ir.ODOT {
  7617  		n := n.(*ir.SelectorExpr)
  7618  		if n.X.Type().NumFields() == 1 {
  7619  			return clobberBase(n.X)
  7620  		}
  7621  	}
  7622  	if n.Op() == ir.OINDEX {
  7623  		n := n.(*ir.IndexExpr)
  7624  		if n.X.Type().IsArray() && n.X.Type().NumElem() == 1 {
  7625  			return clobberBase(n.X)
  7626  		}
  7627  	}
  7628  	return n
  7629  }
  7630  
  7631  // callTargetLSym returns the correct LSym to call 'callee' using its ABI.
  7632  func callTargetLSym(callee *ir.Name) *obj.LSym {
  7633  	if callee.Func == nil {
  7634  		// TODO(austin): This happens in case of interface method I.M from imported package.
  7635  		// It's ABIInternal, and would be better if callee.Func was never nil and we didn't
  7636  		// need this case.
  7637  		return callee.Linksym()
  7638  	}
  7639  
  7640  	return callee.LinksymABI(callee.Func.ABI)
  7641  }
  7642  
  7643  // deferStructFnField is the field index of _defer.fn.
  7644  const deferStructFnField = 4
  7645  
  7646  var deferType *types.Type
  7647  
  7648  // deferstruct returns a type interchangeable with runtime._defer.
  7649  // Make sure this stays in sync with runtime/runtime2.go:_defer.
  7650  func deferstruct() *types.Type {
  7651  	if deferType != nil {
  7652  		return deferType
  7653  	}
  7654  
  7655  	makefield := func(name string, t *types.Type) *types.Field {
  7656  		sym := (*types.Pkg)(nil).Lookup(name)
  7657  		return types.NewField(src.NoXPos, sym, t)
  7658  	}
  7659  
  7660  	fields := []*types.Field{
  7661  		makefield("heap", types.Types[types.TBOOL]),
  7662  		makefield("rangefunc", types.Types[types.TBOOL]),
  7663  		makefield("sp", types.Types[types.TUINTPTR]),
  7664  		makefield("pc", types.Types[types.TUINTPTR]),
  7665  		// Note: the types here don't really matter. Defer structures
  7666  		// are always scanned explicitly during stack copying and GC,
  7667  		// so we make them uintptr type even though they are real pointers.
  7668  		makefield("fn", types.Types[types.TUINTPTR]),
  7669  		makefield("link", types.Types[types.TUINTPTR]),
  7670  		makefield("head", types.Types[types.TUINTPTR]),
  7671  	}
  7672  	if name := fields[deferStructFnField].Sym.Name; name != "fn" {
  7673  		base.Fatalf("deferStructFnField is %q, not fn", name)
  7674  	}
  7675  
  7676  	n := ir.NewDeclNameAt(src.NoXPos, ir.OTYPE, ir.Pkgs.Runtime.Lookup("_defer"))
  7677  	typ := types.NewNamed(n)
  7678  	n.SetType(typ)
  7679  	n.SetTypecheck(1)
  7680  
  7681  	// build struct holding the above fields
  7682  	typ.SetUnderlying(types.NewStruct(fields))
  7683  	types.CalcStructSize(typ)
  7684  
  7685  	deferType = typ
  7686  	return typ
  7687  }
  7688  
  7689  // SpillSlotAddr uses LocalSlot information to initialize an obj.Addr
  7690  // The resulting addr is used in a non-standard context -- in the prologue
  7691  // of a function, before the frame has been constructed, so the standard
  7692  // addressing for the parameters will be wrong.
  7693  func SpillSlotAddr(spill ssa.Spill, baseReg int16, extraOffset int64) obj.Addr {
  7694  	return obj.Addr{
  7695  		Name:   obj.NAME_NONE,
  7696  		Type:   obj.TYPE_MEM,
  7697  		Reg:    baseReg,
  7698  		Offset: spill.Offset + extraOffset,
  7699  	}
  7700  }
  7701  
  7702  var BoundsCheckFunc [ssa.BoundsKindCount]*obj.LSym
  7703