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

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package ssagen
     6  
     7  import (
     8  	"bufio"
     9  	"bytes"
    10  	"cmp"
    11  	"fmt"
    12  	"go/constant"
    13  	"html"
    14  	"internal/buildcfg"
    15  	"internal/runtime/gc"
    16  	"os"
    17  	"path/filepath"
    18  	"slices"
    19  	"strings"
    20  
    21  	"cmd/compile/internal/abi"
    22  	"cmd/compile/internal/base"
    23  	"cmd/compile/internal/ir"
    24  	"cmd/compile/internal/liveness"
    25  	"cmd/compile/internal/objw"
    26  	"cmd/compile/internal/reflectdata"
    27  	"cmd/compile/internal/rttype"
    28  	"cmd/compile/internal/ssa"
    29  	"cmd/compile/internal/staticdata"
    30  	"cmd/compile/internal/typecheck"
    31  	"cmd/compile/internal/types"
    32  	"cmd/internal/obj"
    33  	"cmd/internal/objabi"
    34  	"cmd/internal/src"
    35  	"cmd/internal/sys"
    36  
    37  	rtabi "internal/abi"
    38  )
    39  
    40  var ssaConfig *ssa.Config
    41  var ssaCaches []ssa.Cache
    42  
    43  var ssaDump string     // early copy of $GOSSAFUNC; the func name to dump output for
    44  var ssaDir string      // optional destination for ssa dump file
    45  var ssaDumpStdout bool // whether to dump to stdout
    46  var ssaDumpCFG string  // generate CFGs for these phases
    47  const ssaDumpFile = "ssa.html"
    48  
    49  // ssaDumpInlined holds all inlined functions when ssaDump contains a function name.
    50  var ssaDumpInlined []*ir.Func
    51  
    52  // Maximum size we will aggregate heap allocations of scalar locals.
    53  // Almost certainly can't hurt to be as big as the tiny allocator.
    54  // Might help to be a bit bigger.
    55  const maxAggregatedHeapAllocation = 16
    56  
    57  func DumpInline(fn *ir.Func) {
    58  	if ssaDump != "" && ssaDump == ir.FuncName(fn) {
    59  		ssaDumpInlined = append(ssaDumpInlined, fn)
    60  	}
    61  }
    62  
    63  func InitEnv() {
    64  	ssaDump = os.Getenv("GOSSAFUNC")
    65  	ssaDir = os.Getenv("GOSSADIR")
    66  	if ssaDump != "" {
    67  		if strings.HasSuffix(ssaDump, "+") {
    68  			ssaDump = ssaDump[:len(ssaDump)-1]
    69  			ssaDumpStdout = true
    70  		}
    71  		spl := strings.Split(ssaDump, ":")
    72  		if len(spl) > 1 {
    73  			ssaDump = spl[0]
    74  			ssaDumpCFG = spl[1]
    75  		}
    76  	}
    77  }
    78  
    79  func InitConfig() {
    80  	types_ := ssa.NewTypes()
    81  
    82  	if Arch.SoftFloat {
    83  		softfloatInit()
    84  	}
    85  
    86  	// Generate a few pointer types that are uncommon in the frontend but common in the backend.
    87  	// Caching is disabled in the backend, so generating these here avoids allocations.
    88  	_ = types.NewPtr(types.Types[types.TINTER])                             // *interface{}
    89  	_ = types.NewPtr(types.NewPtr(types.Types[types.TSTRING]))              // **string
    90  	_ = types.NewPtr(types.NewSlice(types.Types[types.TINTER]))             // *[]interface{}
    91  	_ = types.NewPtr(types.NewPtr(types.ByteType))                          // **byte
    92  	_ = types.NewPtr(types.NewSlice(types.ByteType))                        // *[]byte
    93  	_ = types.NewPtr(types.NewSlice(types.Types[types.TSTRING]))            // *[]string
    94  	_ = types.NewPtr(types.NewPtr(types.NewPtr(types.Types[types.TUINT8]))) // ***uint8
    95  	_ = types.NewPtr(types.Types[types.TINT16])                             // *int16
    96  	_ = types.NewPtr(types.Types[types.TINT64])                             // *int64
    97  	_ = types.NewPtr(types.ErrorType)                                       // *error
    98  	_ = types.NewPtr(reflectdata.MapType())                                 // *internal/runtime/maps.Map
    99  	_ = types.NewPtr(deferstruct())                                         // *runtime._defer
   100  	types.NewPtrCacheEnabled = false
   101  	ssaConfig = ssa.NewConfig(base.Ctxt.Arch.Name, *types_, base.Ctxt, base.Flag.N == 0, Arch.SoftFloat)
   102  	ssaConfig.Race = base.Flag.Race
   103  	ssaCaches = make([]ssa.Cache, base.Flag.LowerC)
   104  
   105  	// Set up some runtime functions we'll need to call.
   106  	ir.Syms.AssertE2I = typecheck.LookupRuntimeFunc("assertE2I")
   107  	ir.Syms.AssertE2I2 = typecheck.LookupRuntimeFunc("assertE2I2")
   108  	ir.Syms.CgoCheckMemmove = typecheck.LookupRuntimeFunc("cgoCheckMemmove")
   109  	ir.Syms.CgoCheckPtrWrite = typecheck.LookupRuntimeFunc("cgoCheckPtrWrite")
   110  	ir.Syms.CheckPtrAlignment = typecheck.LookupRuntimeFunc("checkptrAlignment")
   111  	ir.Syms.Deferproc = typecheck.LookupRuntimeFunc("deferproc")
   112  	ir.Syms.Deferprocat = typecheck.LookupRuntimeFunc("deferprocat")
   113  	ir.Syms.DeferprocStack = typecheck.LookupRuntimeFunc("deferprocStack")
   114  	ir.Syms.Deferreturn = typecheck.LookupRuntimeFunc("deferreturn")
   115  	ir.Syms.Duffcopy = typecheck.LookupRuntimeFunc("duffcopy")
   116  	ir.Syms.Duffzero = typecheck.LookupRuntimeFunc("duffzero")
   117  	ir.Syms.GCWriteBarrier[0] = typecheck.LookupRuntimeFunc("gcWriteBarrier1")
   118  	ir.Syms.GCWriteBarrier[1] = typecheck.LookupRuntimeFunc("gcWriteBarrier2")
   119  	ir.Syms.GCWriteBarrier[2] = typecheck.LookupRuntimeFunc("gcWriteBarrier3")
   120  	ir.Syms.GCWriteBarrier[3] = typecheck.LookupRuntimeFunc("gcWriteBarrier4")
   121  	ir.Syms.GCWriteBarrier[4] = typecheck.LookupRuntimeFunc("gcWriteBarrier5")
   122  	ir.Syms.GCWriteBarrier[5] = typecheck.LookupRuntimeFunc("gcWriteBarrier6")
   123  	ir.Syms.GCWriteBarrier[6] = typecheck.LookupRuntimeFunc("gcWriteBarrier7")
   124  	ir.Syms.GCWriteBarrier[7] = typecheck.LookupRuntimeFunc("gcWriteBarrier8")
   125  	ir.Syms.Goschedguarded = typecheck.LookupRuntimeFunc("goschedguarded")
   126  	ir.Syms.Growslice = typecheck.LookupRuntimeFunc("growslice")
   127  	ir.Syms.InterfaceSwitch = typecheck.LookupRuntimeFunc("interfaceSwitch")
   128  	for i := 1; i < len(ir.Syms.MallocGCSmallNoScan); i++ {
   129  		ir.Syms.MallocGCSmallNoScan[i] = typecheck.LookupRuntimeFunc(fmt.Sprintf("mallocgcSmallNoScanSC%d", i))
   130  	}
   131  	for i := 1; i < len(ir.Syms.MallocGCSmallScanNoHeader); i++ {
   132  		ir.Syms.MallocGCSmallScanNoHeader[i] = typecheck.LookupRuntimeFunc(fmt.Sprintf("mallocgcSmallScanNoHeaderSC%d", i))
   133  	}
   134  	for i := 1; i < len(ir.Syms.MallocGCTiny); i++ {
   135  		ir.Syms.MallocGCTiny[i] = typecheck.LookupRuntimeFunc(fmt.Sprintf("mallocTiny%d", i))
   136  	}
   137  	ir.Syms.MallocGC = typecheck.LookupRuntimeFunc("mallocgc")
   138  	ir.Syms.Memmove = typecheck.LookupRuntimeFunc("memmove")
   139  	ir.Syms.Msanread = typecheck.LookupRuntimeFunc("msanread")
   140  	ir.Syms.Msanwrite = typecheck.LookupRuntimeFunc("msanwrite")
   141  	ir.Syms.Msanmove = typecheck.LookupRuntimeFunc("msanmove")
   142  	ir.Syms.Asanread = typecheck.LookupRuntimeFunc("asanread")
   143  	ir.Syms.Asanwrite = typecheck.LookupRuntimeFunc("asanwrite")
   144  	ir.Syms.Newobject = typecheck.LookupRuntimeFunc("newobject")
   145  	ir.Syms.Newproc = typecheck.LookupRuntimeFunc("newproc")
   146  	ir.Syms.PanicBounds = typecheck.LookupRuntimeFunc("panicBounds")
   147  	ir.Syms.PanicExtend = typecheck.LookupRuntimeFunc("panicExtend")
   148  	ir.Syms.Panicdivide = typecheck.LookupRuntimeFunc("panicdivide")
   149  	ir.Syms.PanicdottypeE = typecheck.LookupRuntimeFunc("panicdottypeE")
   150  	ir.Syms.PanicdottypeI = typecheck.LookupRuntimeFunc("panicdottypeI")
   151  	ir.Syms.Panicnildottype = typecheck.LookupRuntimeFunc("panicnildottype")
   152  	ir.Syms.Panicoverflow = typecheck.LookupRuntimeFunc("panicoverflow")
   153  	ir.Syms.Panicshift = typecheck.LookupRuntimeFunc("panicshift")
   154  	ir.Syms.Racefuncenter = typecheck.LookupRuntimeFunc("racefuncenter")
   155  	ir.Syms.Racefuncexit = typecheck.LookupRuntimeFunc("racefuncexit")
   156  	ir.Syms.Raceread = typecheck.LookupRuntimeFunc("raceread")
   157  	ir.Syms.Racereadrange = typecheck.LookupRuntimeFunc("racereadrange")
   158  	ir.Syms.Racewrite = typecheck.LookupRuntimeFunc("racewrite")
   159  	ir.Syms.Racewriterange = typecheck.LookupRuntimeFunc("racewriterange")
   160  	ir.Syms.TypeAssert = typecheck.LookupRuntimeFunc("typeAssert")
   161  	ir.Syms.WBZero = typecheck.LookupRuntimeFunc("wbZero")
   162  	ir.Syms.WBMove = typecheck.LookupRuntimeFunc("wbMove")
   163  	ir.Syms.X86HasPOPCNT = typecheck.LookupRuntimeVar("x86HasPOPCNT")         // bool
   164  	ir.Syms.X86HasSSE41 = typecheck.LookupRuntimeVar("x86HasSSE41")           // bool
   165  	ir.Syms.X86HasFMA = typecheck.LookupRuntimeVar("x86HasFMA")               // bool
   166  	ir.Syms.ARMHasVFPv4 = typecheck.LookupRuntimeVar("armHasVFPv4")           // bool
   167  	ir.Syms.ARM64HasATOMICS = typecheck.LookupRuntimeVar("arm64HasATOMICS")   // bool
   168  	ir.Syms.Loong64HasLAMCAS = typecheck.LookupRuntimeVar("loong64HasLAMCAS") // bool
   169  	ir.Syms.Loong64HasLAM_BH = typecheck.LookupRuntimeVar("loong64HasLAM_BH") // bool
   170  	ir.Syms.Loong64HasLSX = typecheck.LookupRuntimeVar("loong64HasLSX")       // bool
   171  	ir.Syms.RISCV64HasZbb = typecheck.LookupRuntimeVar("riscv64HasZbb")       // bool
   172  	ir.Syms.Staticuint64s = typecheck.LookupRuntimeVar("staticuint64s")
   173  	ir.Syms.Typedmemmove = typecheck.LookupRuntimeFunc("typedmemmove")
   174  	ir.Syms.Udiv = typecheck.LookupRuntimeVar("udiv")                 // asm func with special ABI
   175  	ir.Syms.WriteBarrier = typecheck.LookupRuntimeVar("writeBarrier") // struct { bool; ... }
   176  	ir.Syms.Zerobase = typecheck.LookupRuntimeVar("zerobase")
   177  	ir.Syms.ZeroVal = typecheck.LookupRuntimeVar("zeroVal")
   178  
   179  	if Arch.LinkArch.Family == sys.Wasm {
   180  		BoundsCheckFunc[ssa.BoundsIndex] = typecheck.LookupRuntimeFunc("goPanicIndex")
   181  		BoundsCheckFunc[ssa.BoundsIndexU] = typecheck.LookupRuntimeFunc("goPanicIndexU")
   182  		BoundsCheckFunc[ssa.BoundsSliceAlen] = typecheck.LookupRuntimeFunc("goPanicSliceAlen")
   183  		BoundsCheckFunc[ssa.BoundsSliceAlenU] = typecheck.LookupRuntimeFunc("goPanicSliceAlenU")
   184  		BoundsCheckFunc[ssa.BoundsSliceAcap] = typecheck.LookupRuntimeFunc("goPanicSliceAcap")
   185  		BoundsCheckFunc[ssa.BoundsSliceAcapU] = typecheck.LookupRuntimeFunc("goPanicSliceAcapU")
   186  		BoundsCheckFunc[ssa.BoundsSliceB] = typecheck.LookupRuntimeFunc("goPanicSliceB")
   187  		BoundsCheckFunc[ssa.BoundsSliceBU] = typecheck.LookupRuntimeFunc("goPanicSliceBU")
   188  		BoundsCheckFunc[ssa.BoundsSlice3Alen] = typecheck.LookupRuntimeFunc("goPanicSlice3Alen")
   189  		BoundsCheckFunc[ssa.BoundsSlice3AlenU] = typecheck.LookupRuntimeFunc("goPanicSlice3AlenU")
   190  		BoundsCheckFunc[ssa.BoundsSlice3Acap] = typecheck.LookupRuntimeFunc("goPanicSlice3Acap")
   191  		BoundsCheckFunc[ssa.BoundsSlice3AcapU] = typecheck.LookupRuntimeFunc("goPanicSlice3AcapU")
   192  		BoundsCheckFunc[ssa.BoundsSlice3B] = typecheck.LookupRuntimeFunc("goPanicSlice3B")
   193  		BoundsCheckFunc[ssa.BoundsSlice3BU] = typecheck.LookupRuntimeFunc("goPanicSlice3BU")
   194  		BoundsCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeFunc("goPanicSlice3C")
   195  		BoundsCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeFunc("goPanicSlice3CU")
   196  		BoundsCheckFunc[ssa.BoundsConvert] = typecheck.LookupRuntimeFunc("goPanicSliceConvert")
   197  	}
   198  
   199  	// Wasm (all asm funcs with special ABIs)
   200  	ir.Syms.WasmDiv = typecheck.LookupRuntimeVar("wasmDiv")
   201  	ir.Syms.WasmTruncS = typecheck.LookupRuntimeVar("wasmTruncS")
   202  	ir.Syms.WasmTruncU = typecheck.LookupRuntimeVar("wasmTruncU")
   203  	ir.Syms.SigPanic = typecheck.LookupRuntimeFunc("sigpanic")
   204  }
   205  
   206  func InitTables() {
   207  	initIntrinsics(nil)
   208  }
   209  
   210  // AbiForBodylessFuncStackMap returns the ABI for a bodyless function's stack map.
   211  // This is not necessarily the ABI used to call it.
   212  // Currently (1.17 dev) such a stack map is always ABI0;
   213  // any ABI wrapper that is present is nosplit, hence a precise
   214  // stack map is not needed there (the parameters survive only long
   215  // enough to call the wrapped assembly function).
   216  // This always returns a freshly copied ABI.
   217  func AbiForBodylessFuncStackMap(fn *ir.Func) *abi.ABIConfig {
   218  	return ssaConfig.ABI0.Copy() // No idea what races will result, be safe
   219  }
   220  
   221  // abiForFunc implements ABI policy for a function, but does not return a copy of the ABI.
   222  // Passing a nil function returns the default ABI based on experiment configuration.
   223  func abiForFunc(fn *ir.Func, abi0, abi1 *abi.ABIConfig) *abi.ABIConfig {
   224  	if buildcfg.Experiment.RegabiArgs {
   225  		// Select the ABI based on the function's defining ABI.
   226  		if fn == nil {
   227  			return abi1
   228  		}
   229  		switch fn.ABI {
   230  		case obj.ABI0:
   231  			return abi0
   232  		case obj.ABIInternal:
   233  			// TODO(austin): Clean up the nomenclature here.
   234  			// It's not clear that "abi1" is ABIInternal.
   235  			return abi1
   236  		}
   237  		base.Fatalf("function %v has unknown ABI %v", fn, fn.ABI)
   238  		panic("not reachable")
   239  	}
   240  
   241  	a := abi0
   242  	if fn != nil {
   243  		if fn.Pragma&ir.RegisterParams != 0 { // TODO(register args) remove after register abi is working
   244  			a = abi1
   245  		}
   246  	}
   247  	return a
   248  }
   249  
   250  // emitOpenDeferInfo emits FUNCDATA information about the defers in a function
   251  // that is using open-coded defers.  This funcdata is used to determine the active
   252  // defers in a function and execute those defers during panic processing.
   253  //
   254  // The funcdata is all encoded in varints (since values will almost always be less than
   255  // 128, but stack offsets could potentially be up to 2Gbyte). All "locations" (offsets)
   256  // for stack variables are specified as the number of bytes below varp (pointer to the
   257  // top of the local variables) for their starting address. The format is:
   258  //
   259  //   - Offset of the deferBits variable
   260  //   - Offset of the first closure slot (the rest are laid out consecutively).
   261  func (s *state) emitOpenDeferInfo() {
   262  	firstOffset := s.openDefers[0].closureNode.FrameOffset()
   263  
   264  	// Verify that cmpstackvarlt laid out the slots in order.
   265  	for i, r := range s.openDefers {
   266  		have := r.closureNode.FrameOffset()
   267  		want := firstOffset + int64(i)*int64(types.PtrSize)
   268  		if have != want {
   269  			base.FatalfAt(s.curfn.Pos(), "unexpected frame offset for open-coded defer slot #%v: have %v, want %v", i, have, want)
   270  		}
   271  	}
   272  
   273  	x := base.Ctxt.Lookup(s.curfn.LSym.Name + ".opendefer")
   274  	x.Set(obj.AttrContentAddressable, true)
   275  	s.curfn.LSym.Func().OpenCodedDeferInfo = x
   276  
   277  	off := 0
   278  	off = objw.Uvarint(x, off, uint64(-s.deferBitsTemp.FrameOffset()))
   279  	off = objw.Uvarint(x, off, uint64(-firstOffset))
   280  }
   281  
   282  // buildssa builds an SSA function for fn.
   283  // worker indicates which of the backend workers is doing the processing.
   284  func buildssa(fn *ir.Func, worker int, isPgoHot bool) *ssa.Func {
   285  	name := ir.FuncName(fn)
   286  
   287  	abiSelf := abiForFunc(fn, ssaConfig.ABI0, ssaConfig.ABI1)
   288  
   289  	printssa := false
   290  	// match either a simple name e.g. "(*Reader).Reset", package.name e.g. "compress/gzip.(*Reader).Reset", or subpackage name "gzip.(*Reader).Reset"
   291  	// optionally allows an ABI suffix specification in the GOSSAHASH, e.g. "(*Reader).Reset<0>" etc
   292  	if strings.Contains(ssaDump, name) { // in all the cases the function name is entirely contained within the GOSSAFUNC string.
   293  		nameOptABI := name
   294  		if l := len(ssaDump); l > 1 && ssaDump[l-2] == ',' { // ABI specification
   295  			nameOptABI = ssa.FuncNameABI(name, abiSelf.Which())
   296  		} else if strings.HasSuffix(ssaDump, ">") { // if they use the linker syntax instead....
   297  			l := len(ssaDump)
   298  			if l >= 3 && ssaDump[l-3] == '<' {
   299  				nameOptABI = ssa.FuncNameABI(name, abiSelf.Which())
   300  				ssaDump = ssaDump[:l-3] + "," + ssaDump[l-2:l-1]
   301  			}
   302  		}
   303  		pkgDotName := base.Ctxt.Pkgpath + "." + nameOptABI
   304  		printssa = nameOptABI == ssaDump || // "(*Reader).Reset"
   305  			pkgDotName == ssaDump || // "compress/gzip.(*Reader).Reset"
   306  			strings.HasSuffix(pkgDotName, ssaDump) && strings.HasSuffix(pkgDotName, "/"+ssaDump) // "gzip.(*Reader).Reset"
   307  	}
   308  
   309  	var astBuf *bytes.Buffer
   310  	if printssa {
   311  		astBuf = &bytes.Buffer{}
   312  		ir.FDumpList(astBuf, "buildssa-body", fn.Body)
   313  		if ssaDumpStdout {
   314  			fmt.Println("generating SSA for", name)
   315  			fmt.Print(astBuf.String())
   316  		}
   317  	}
   318  
   319  	var s state
   320  	s.pushLine(fn.Pos())
   321  	defer s.popLine()
   322  
   323  	s.hasdefer = fn.HasDefer()
   324  	if fn.Pragma&ir.CgoUnsafeArgs != 0 {
   325  		s.cgoUnsafeArgs = true
   326  	}
   327  	s.checkPtrEnabled = ir.ShouldCheckPtr(fn, 1)
   328  
   329  	if base.Flag.Cfg.Instrumenting && fn.Pragma&ir.Norace == 0 && !fn.Linksym().ABIWrapper() {
   330  		if !base.Flag.Race || !objabi.LookupPkgSpecial(fn.Sym().Pkg.Path).NoRaceFunc {
   331  			s.instrumentMemory = true
   332  		}
   333  		if base.Flag.Race {
   334  			s.instrumentEnterExit = true
   335  		}
   336  	}
   337  
   338  	fe := ssafn{
   339  		curfn: fn,
   340  		log:   printssa && ssaDumpStdout,
   341  	}
   342  	s.curfn = fn
   343  
   344  	cache := &ssaCaches[worker]
   345  	cache.Reset()
   346  
   347  	s.f = ssaConfig.NewFunc(&fe, cache)
   348  	s.config = ssaConfig
   349  	s.f.Type = fn.Type()
   350  	s.f.Name = name
   351  	s.f.PrintOrHtmlSSA = printssa
   352  	if fn.Pragma&ir.Nosplit != 0 {
   353  		s.f.NoSplit = true
   354  	}
   355  	s.f.ABI0 = ssaConfig.ABI0
   356  	s.f.ABI1 = ssaConfig.ABI1
   357  	s.f.ABIDefault = abiForFunc(nil, ssaConfig.ABI0, ssaConfig.ABI1)
   358  	s.f.ABISelf = abiSelf
   359  
   360  	s.panics = map[funcLine]*ssa.Block{}
   361  	s.softFloat = s.config.SoftFloat
   362  
   363  	// Allocate starting block
   364  	s.f.Entry = s.f.NewBlock(ssa.BlockPlain)
   365  	s.f.Entry.Pos = fn.Pos()
   366  	s.f.IsPgoHot = isPgoHot
   367  
   368  	if printssa {
   369  		ssaDF := ssaDumpFile
   370  		if ssaDir != "" {
   371  			ssaDF = filepath.Join(ssaDir, base.Ctxt.Pkgpath+"."+s.f.NameABI()+".html")
   372  			ssaD := filepath.Dir(ssaDF)
   373  			os.MkdirAll(ssaD, 0755)
   374  		}
   375  		s.f.HTMLWriter = ssa.NewHTMLWriter(ssaDF, s.f, ssaDumpCFG)
   376  		// TODO: generate and print a mapping from nodes to values and blocks
   377  		dumpSourcesColumn(s.f.HTMLWriter, fn)
   378  		s.f.HTMLWriter.WriteAST("AST", astBuf)
   379  	}
   380  
   381  	// Allocate starting values
   382  	s.labels = map[string]*ssaLabel{}
   383  	s.fwdVars = map[ir.Node]*ssa.Value{}
   384  	s.startmem = s.entryNewValue0(ssa.OpInitMem, types.TypeMem)
   385  
   386  	s.hasOpenDefers = base.Flag.N == 0 && s.hasdefer && !s.curfn.OpenCodedDeferDisallowed()
   387  	switch {
   388  	case base.Debug.NoOpenDefer != 0:
   389  		s.hasOpenDefers = false
   390  	case s.hasOpenDefers && (base.Ctxt.Flag_shared || base.Ctxt.Flag_dynlink) && base.Ctxt.Arch.Name == "386":
   391  		// Don't support open-coded defers for 386 ONLY when using shared
   392  		// libraries, because there is extra code (added by rewriteToUseGot())
   393  		// preceding the deferreturn/ret code that we don't track correctly.
   394  		//
   395  		// TODO this restriction can be removed given adjusted offset in computeDeferReturn in cmd/link/internal/ld/pcln.go
   396  		s.hasOpenDefers = false
   397  	}
   398  	if s.hasOpenDefers && s.instrumentEnterExit {
   399  		// Skip doing open defers if we need to instrument function
   400  		// returns for the race detector, since we will not generate that
   401  		// code in the case of the extra deferreturn/ret segment.
   402  		s.hasOpenDefers = false
   403  	}
   404  	if s.hasOpenDefers {
   405  		// Similarly, skip if there are any heap-allocated result
   406  		// parameters that need to be copied back to their stack slots.
   407  		for _, f := range s.curfn.Type().Results() {
   408  			if !f.Nname.(*ir.Name).OnStack() {
   409  				s.hasOpenDefers = false
   410  				break
   411  			}
   412  		}
   413  	}
   414  	if s.hasOpenDefers &&
   415  		s.curfn.NumReturns*s.curfn.NumDefers > 15 {
   416  		// Since we are generating defer calls at every exit for
   417  		// open-coded defers, skip doing open-coded defers if there are
   418  		// too many returns (especially if there are multiple defers).
   419  		// Open-coded defers are most important for improving performance
   420  		// for smaller functions (which don't have many returns).
   421  		s.hasOpenDefers = false
   422  	}
   423  
   424  	s.sp = s.entryNewValue0(ssa.OpSP, types.Types[types.TUINTPTR]) // TODO: use generic pointer type (unsafe.Pointer?) instead
   425  	s.sb = s.entryNewValue0(ssa.OpSB, types.Types[types.TUINTPTR])
   426  
   427  	s.startBlock(s.f.Entry)
   428  	s.vars[memVar] = s.startmem
   429  	if s.hasOpenDefers {
   430  		// Create the deferBits variable and stack slot.  deferBits is a
   431  		// bitmask showing which of the open-coded defers in this function
   432  		// have been activated.
   433  		deferBitsTemp := typecheck.TempAt(src.NoXPos, s.curfn, types.Types[types.TUINT8])
   434  		deferBitsTemp.SetAddrtaken(true)
   435  		s.deferBitsTemp = deferBitsTemp
   436  		// For this value, AuxInt is initialized to zero by default
   437  		startDeferBits := s.entryNewValue0(ssa.OpConst8, types.Types[types.TUINT8])
   438  		s.vars[deferBitsVar] = startDeferBits
   439  		s.deferBitsAddr = s.addr(deferBitsTemp)
   440  		s.store(types.Types[types.TUINT8], s.deferBitsAddr, startDeferBits)
   441  		// Make sure that the deferBits stack slot is kept alive (for use
   442  		// by panics) and stores to deferBits are not eliminated, even if
   443  		// all checking code on deferBits in the function exit can be
   444  		// eliminated, because the defer statements were all
   445  		// unconditional.
   446  		s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, deferBitsTemp, s.mem(), false)
   447  	}
   448  
   449  	var params *abi.ABIParamResultInfo
   450  	params = s.f.ABISelf.ABIAnalyze(fn.Type(), true)
   451  
   452  	// The backend's stackframe pass prunes away entries from the fn's
   453  	// Dcl list, including PARAMOUT nodes that correspond to output
   454  	// params passed in registers. Walk the Dcl list and capture these
   455  	// nodes to a side list, so that we'll have them available during
   456  	// DWARF-gen later on. See issue 48573 for more details.
   457  	var debugInfo ssa.FuncDebug
   458  	for _, n := range fn.Dcl {
   459  		if n.Class == ir.PPARAMOUT && n.IsOutputParamInRegisters() {
   460  			debugInfo.RegOutputParams = append(debugInfo.RegOutputParams, n)
   461  		}
   462  	}
   463  	fn.DebugInfo = &debugInfo
   464  
   465  	// Generate addresses of local declarations
   466  	s.decladdrs = map[*ir.Name]*ssa.Value{}
   467  	for _, n := range fn.Dcl {
   468  		switch n.Class {
   469  		case ir.PPARAM:
   470  			// Be aware that blank and unnamed input parameters will not appear here, but do appear in the type
   471  			s.decladdrs[n] = s.entryNewValue2A(ssa.OpLocalAddr, types.NewPtr(n.Type()), n, s.sp, s.startmem)
   472  		case ir.PPARAMOUT:
   473  			s.decladdrs[n] = s.entryNewValue2A(ssa.OpLocalAddr, types.NewPtr(n.Type()), n, s.sp, s.startmem)
   474  		case ir.PAUTO:
   475  			// processed at each use, to prevent Addr coming
   476  			// before the decl.
   477  		default:
   478  			s.Fatalf("local variable with class %v unimplemented", n.Class)
   479  		}
   480  	}
   481  
   482  	s.f.OwnAux = ssa.OwnAuxCall(fn.LSym, params)
   483  
   484  	// Populate SSAable arguments.
   485  	for _, n := range fn.Dcl {
   486  		if n.Class == ir.PPARAM {
   487  			if s.canSSA(n) {
   488  				v := s.newValue0A(ssa.OpArg, n.Type(), n)
   489  				s.vars[n] = v
   490  				s.addNamedValue(n, v) // This helps with debugging information, not needed for compilation itself.
   491  			} else { // address was taken AND/OR too large for SSA
   492  				paramAssignment := ssa.ParamAssignmentForArgName(s.f, n)
   493  				if len(paramAssignment.Registers) > 0 {
   494  					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.
   495  						v := s.newValue0A(ssa.OpArg, n.Type(), n)
   496  						s.store(n.Type(), s.decladdrs[n], v)
   497  					} else { // Too big for SSA.
   498  						// Brute force, and early, do a bunch of stores from registers
   499  						// Note that expand calls knows about this and doesn't trouble itself with larger-than-SSA-able Args in registers.
   500  						s.storeParameterRegsToStack(s.f.ABISelf, paramAssignment, n, s.decladdrs[n], false)
   501  					}
   502  				}
   503  			}
   504  		}
   505  	}
   506  
   507  	// Populate closure variables.
   508  	if fn.Needctxt() {
   509  		clo := s.entryNewValue0(ssa.OpGetClosurePtr, s.f.Config.Types.BytePtr)
   510  		if fn.RangeParent != nil && base.Flag.N != 0 {
   511  			// For a range body closure, keep its closure pointer live on the
   512  			// stack with a special name, so the debugger can look for it and
   513  			// find the parent frame.
   514  			sym := &types.Sym{Name: ".closureptr", Pkg: types.LocalPkg}
   515  			cloSlot := s.curfn.NewLocal(src.NoXPos, sym, s.f.Config.Types.BytePtr)
   516  			cloSlot.SetUsed(true)
   517  			cloSlot.SetEsc(ir.EscNever)
   518  			cloSlot.SetAddrtaken(true)
   519  			s.f.CloSlot = cloSlot
   520  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, cloSlot, s.mem(), false)
   521  			addr := s.addr(cloSlot)
   522  			s.store(s.f.Config.Types.BytePtr, addr, clo)
   523  			// Keep it from being dead-store eliminated.
   524  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, cloSlot, s.mem(), false)
   525  		}
   526  		csiter := typecheck.NewClosureStructIter(fn.ClosureVars)
   527  		for {
   528  			n, typ, offset := csiter.Next()
   529  			if n == nil {
   530  				break
   531  			}
   532  
   533  			ptr := s.newValue1I(ssa.OpOffPtr, types.NewPtr(typ), offset, clo)
   534  
   535  			// If n is a small variable captured by value, promote
   536  			// it to PAUTO so it can be converted to SSA.
   537  			//
   538  			// Note: While we never capture a variable by value if
   539  			// the user took its address, we may have generated
   540  			// runtime calls that did (#43701). Since we don't
   541  			// convert Addrtaken variables to SSA anyway, no point
   542  			// in promoting them either.
   543  			if n.Byval() && !n.Addrtaken() && ssa.CanSSA(n.Type()) {
   544  				n.Class = ir.PAUTO
   545  				fn.Dcl = append(fn.Dcl, n)
   546  				s.assign(n, s.load(n.Type(), ptr), false, 0)
   547  				continue
   548  			}
   549  
   550  			if !n.Byval() {
   551  				ptr = s.load(typ, ptr)
   552  			}
   553  			s.setHeapaddr(fn.Pos(), n, ptr)
   554  		}
   555  	}
   556  
   557  	// Convert the AST-based IR to the SSA-based IR
   558  	if s.instrumentEnterExit {
   559  		s.rtcall(ir.Syms.Racefuncenter, true, nil, s.newValue0(ssa.OpGetCallerPC, types.Types[types.TUINTPTR]))
   560  	}
   561  	s.zeroResults()
   562  	s.paramsToHeap()
   563  	s.stmtList(fn.Body)
   564  
   565  	// fallthrough to exit
   566  	if s.curBlock != nil {
   567  		s.pushLine(fn.Endlineno)
   568  		s.exit()
   569  		s.popLine()
   570  	}
   571  
   572  	for _, b := range s.f.Blocks {
   573  		if b.Pos != src.NoXPos {
   574  			s.updateUnsetPredPos(b)
   575  		}
   576  	}
   577  
   578  	s.f.HTMLWriter.WritePhase("before insert phis", "before insert phis")
   579  
   580  	s.insertPhis()
   581  
   582  	// Main call to ssa package to compile function
   583  	ssa.Compile(s.f)
   584  
   585  	fe.AllocFrame(s.f)
   586  
   587  	if len(s.openDefers) != 0 {
   588  		s.emitOpenDeferInfo()
   589  	}
   590  
   591  	// Record incoming parameter spill information for morestack calls emitted in the assembler.
   592  	// This is done here, using all the parameters (used, partially used, and unused) because
   593  	// it mimics the behavior of the former ABI (everything stored) and because it's not 100%
   594  	// clear if naming conventions are respected in autogenerated code.
   595  	// TODO figure out exactly what's unused, don't spill it. Make liveness fine-grained, also.
   596  	for _, p := range params.InParams() {
   597  		typs, offs := p.RegisterTypesAndOffsets()
   598  		for i, t := range typs {
   599  			o := offs[i]                // offset within parameter
   600  			fo := p.FrameOffset(params) // offset of parameter in frame
   601  			reg := ssa.ObjRegForAbiReg(p.Registers[i], s.f.Config)
   602  			s.f.RegArgs = append(s.f.RegArgs, ssa.Spill{Reg: reg, Offset: fo + o, Type: t})
   603  		}
   604  	}
   605  
   606  	return s.f
   607  }
   608  
   609  func (s *state) storeParameterRegsToStack(abi *abi.ABIConfig, paramAssignment *abi.ABIParamAssignment, n *ir.Name, addr *ssa.Value, pointersOnly bool) {
   610  	typs, offs := paramAssignment.RegisterTypesAndOffsets()
   611  	for i, t := range typs {
   612  		if pointersOnly && !t.IsPtrShaped() {
   613  			continue
   614  		}
   615  		r := paramAssignment.Registers[i]
   616  		o := offs[i]
   617  		op, reg := ssa.ArgOpAndRegisterFor(r, abi)
   618  		aux := &ssa.AuxNameOffset{Name: n, Offset: o}
   619  		v := s.newValue0I(op, t, reg)
   620  		v.Aux = aux
   621  		p := s.newValue1I(ssa.OpOffPtr, types.NewPtr(t), o, addr)
   622  		s.store(t, p, v)
   623  	}
   624  }
   625  
   626  // zeroResults zeros the return values at the start of the function.
   627  // We need to do this very early in the function.  Defer might stop a
   628  // panic and show the return values as they exist at the time of
   629  // panic.  For precise stacks, the garbage collector assumes results
   630  // are always live, so we need to zero them before any allocations,
   631  // even allocations to move params/results to the heap.
   632  func (s *state) zeroResults() {
   633  	for _, f := range s.curfn.Type().Results() {
   634  		n := f.Nname.(*ir.Name)
   635  		if !n.OnStack() {
   636  			// The local which points to the return value is the
   637  			// thing that needs zeroing. This is already handled
   638  			// by a Needzero annotation in plive.go:(*liveness).epilogue.
   639  			continue
   640  		}
   641  		// Zero the stack location containing f.
   642  		if typ := n.Type(); ssa.CanSSA(typ) {
   643  			s.assign(n, s.zeroVal(typ), false, 0)
   644  		} else {
   645  			if typ.HasPointers() || ssa.IsMergeCandidate(n) {
   646  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
   647  			}
   648  			s.zero(n.Type(), s.decladdrs[n])
   649  		}
   650  	}
   651  }
   652  
   653  // paramsToHeap produces code to allocate memory for heap-escaped parameters
   654  // and to copy non-result parameters' values from the stack.
   655  func (s *state) paramsToHeap() {
   656  	do := func(params []*types.Field) {
   657  		for _, f := range params {
   658  			if f.Nname == nil {
   659  				continue // anonymous or blank parameter
   660  			}
   661  			n := f.Nname.(*ir.Name)
   662  			if ir.IsBlank(n) || n.OnStack() {
   663  				continue
   664  			}
   665  			s.newHeapaddr(n)
   666  			if n.Class == ir.PPARAM {
   667  				s.move(n.Type(), s.expr(n.Heapaddr), s.decladdrs[n])
   668  			}
   669  		}
   670  	}
   671  
   672  	typ := s.curfn.Type()
   673  	do(typ.Recvs())
   674  	do(typ.Params())
   675  	do(typ.Results())
   676  }
   677  
   678  // allocSizeAndAlign returns the size and alignment of t.
   679  // Normally just t.Size() and t.Alignment(), but there
   680  // is a special case to handle 64-bit atomics on 32-bit systems.
   681  func allocSizeAndAlign(t *types.Type) (int64, int64) {
   682  	size, align := t.Size(), t.Alignment()
   683  	if types.PtrSize == 4 && align == 4 && size >= 8 {
   684  		// For 64-bit atomics on 32-bit systems.
   685  		size = types.RoundUp(size, 8)
   686  		align = 8
   687  	}
   688  	return size, align
   689  }
   690  func allocSize(t *types.Type) int64 {
   691  	size, _ := allocSizeAndAlign(t)
   692  	return size
   693  }
   694  func allocAlign(t *types.Type) int64 {
   695  	_, align := allocSizeAndAlign(t)
   696  	return align
   697  }
   698  
   699  // newHeapaddr allocates heap memory for n and sets its heap address.
   700  func (s *state) newHeapaddr(n *ir.Name) {
   701  	size := allocSize(n.Type())
   702  	if n.Type().HasPointers() || size >= maxAggregatedHeapAllocation || size == 0 {
   703  		s.setHeapaddr(n.Pos(), n, s.newObject(n.Type()))
   704  		return
   705  	}
   706  
   707  	// Do we have room together with our pending allocations?
   708  	// If not, flush all the current ones.
   709  	var used int64
   710  	for _, v := range s.pendingHeapAllocations {
   711  		used += allocSize(v.Type.Elem())
   712  	}
   713  	if used+size > maxAggregatedHeapAllocation {
   714  		s.flushPendingHeapAllocations()
   715  	}
   716  
   717  	var allocCall *ssa.Value // (SelectN [0] (call of runtime.newobject))
   718  	if len(s.pendingHeapAllocations) == 0 {
   719  		// Make an allocation, but the type being allocated is just
   720  		// the first pending object. We will come back and update it
   721  		// later if needed.
   722  		allocCall = s.newObjectNonSpecialized(n.Type(), nil)
   723  	} else {
   724  		allocCall = s.pendingHeapAllocations[0].Args[0]
   725  	}
   726  	// v is an offset to the shared allocation. Offsets are dummy 0s for now.
   727  	v := s.newValue1I(ssa.OpOffPtr, n.Type().PtrTo(), 0, allocCall)
   728  
   729  	// Add to list of pending allocations.
   730  	s.pendingHeapAllocations = append(s.pendingHeapAllocations, v)
   731  
   732  	// Finally, record for posterity.
   733  	s.setHeapaddr(n.Pos(), n, v)
   734  }
   735  
   736  func (s *state) flushPendingHeapAllocations() {
   737  	pending := s.pendingHeapAllocations
   738  	if len(pending) == 0 {
   739  		return // nothing to do
   740  	}
   741  	s.pendingHeapAllocations = nil // reset state
   742  	ptr := pending[0].Args[0]      // The SelectN [0] op
   743  	call := ptr.Args[0]            // The runtime.newobject call
   744  
   745  	if len(pending) == 1 {
   746  		// Just a single object, do a standard allocation.
   747  		v := pending[0]
   748  		v.Op = ssa.OpCopy // instead of OffPtr [0]
   749  		return
   750  	}
   751  
   752  	// Sort in decreasing alignment.
   753  	// This way we never have to worry about padding.
   754  	// (Stable not required; just cleaner to keep program order among equal alignments.)
   755  	slices.SortStableFunc(pending, func(x, y *ssa.Value) int {
   756  		return cmp.Compare(allocAlign(y.Type.Elem()), allocAlign(x.Type.Elem()))
   757  	})
   758  
   759  	// Figure out how much data we need allocate.
   760  	var size int64
   761  	for _, v := range pending {
   762  		v.AuxInt = size // Adjust OffPtr to the right value while we are here.
   763  		size += allocSize(v.Type.Elem())
   764  	}
   765  	align := allocAlign(pending[0].Type.Elem())
   766  	size = types.RoundUp(size, align)
   767  
   768  	// Convert newObject call to a mallocgc call.
   769  	args := []*ssa.Value{
   770  		s.constInt(types.Types[types.TUINTPTR], size),
   771  		s.constNil(call.Args[0].Type), // a nil *runtime._type
   772  		s.constBool(true),             // needZero TODO: false is ok?
   773  		call.Args[1],                  // memory
   774  	}
   775  	mallocSym := ir.Syms.MallocGC
   776  	if specialMallocSym := s.specializedMallocSym(size, false); specialMallocSym != nil {
   777  		mallocSym = specialMallocSym
   778  	}
   779  	call.Aux = ssa.StaticAuxCall(mallocSym, s.f.ABIDefault.ABIAnalyzeTypes(
   780  		[]*types.Type{args[0].Type, args[1].Type, args[2].Type},
   781  		[]*types.Type{types.Types[types.TUNSAFEPTR]},
   782  	))
   783  	call.AuxInt = 4 * s.config.PtrSize // arg+results size, uintptr/ptr/bool/ptr
   784  	call.SetArgs4(args[0], args[1], args[2], args[3])
   785  	// TODO: figure out how to pass alignment to runtime
   786  
   787  	call.Type = types.NewTuple(types.Types[types.TUNSAFEPTR], types.TypeMem)
   788  	ptr.Type = types.Types[types.TUNSAFEPTR]
   789  }
   790  
   791  func (s *state) specializedMallocSym(size int64, hasPointers bool) *obj.LSym {
   792  	if !s.sizeSpecializedMallocEnabled() {
   793  		return nil
   794  	}
   795  	ptrSize := s.config.PtrSize
   796  	ptrBits := ptrSize * 8
   797  	minSizeForMallocHeader := ptrSize * ptrBits
   798  	heapBitsInSpan := size <= minSizeForMallocHeader
   799  	if !heapBitsInSpan {
   800  		return nil
   801  	}
   802  	divRoundUp := func(n, a uintptr) uintptr { return (n + a - 1) / a }
   803  	sizeClass := gc.SizeToSizeClass8[divRoundUp(uintptr(size), gc.SmallSizeDiv)]
   804  	if hasPointers {
   805  		return ir.Syms.MallocGCSmallScanNoHeader[sizeClass]
   806  	}
   807  	if size < gc.TinySize {
   808  		return ir.Syms.MallocGCTiny[size]
   809  	}
   810  	return ir.Syms.MallocGCSmallNoScan[sizeClass]
   811  }
   812  
   813  func (s *state) sizeSpecializedMallocEnabled() bool {
   814  	if base.Flag.CompilingRuntime {
   815  		// The compiler forces the values of the asan, msan, and race flags to false if
   816  		// we're compiling the runtime, so we lose the information about whether we're
   817  		// building in asan, msan, or race mode. Because the specialized functions don't
   818  		// work in that mode, just turn if off in that case.
   819  		// TODO(matloob): Save the information about whether the flags were passed in
   820  		// originally so we can turn off size specialized malloc in that case instead
   821  		// using Instrumenting below. Then we can remove this condition.
   822  		return false
   823  	}
   824  
   825  	return buildcfg.Experiment.SizeSpecializedMalloc && !base.Flag.Cfg.Instrumenting
   826  }
   827  
   828  // setHeapaddr allocates a new PAUTO variable to store ptr (which must be non-nil)
   829  // and then sets it as n's heap address.
   830  func (s *state) setHeapaddr(pos src.XPos, n *ir.Name, ptr *ssa.Value) {
   831  	if !ptr.Type.IsPtr() || !types.Identical(n.Type(), ptr.Type.Elem()) {
   832  		base.FatalfAt(n.Pos(), "setHeapaddr %L with type %v", n, ptr.Type)
   833  	}
   834  
   835  	// Declare variable to hold address.
   836  	sym := &types.Sym{Name: "&" + n.Sym().Name, Pkg: types.LocalPkg}
   837  	addr := s.curfn.NewLocal(pos, sym, types.NewPtr(n.Type()))
   838  	addr.SetUsed(true)
   839  	types.CalcSize(addr.Type())
   840  
   841  	if n.Class == ir.PPARAMOUT {
   842  		addr.SetIsOutputParamHeapAddr(true)
   843  	}
   844  
   845  	n.Heapaddr = addr
   846  	s.assign(addr, ptr, false, 0)
   847  }
   848  
   849  // newObject returns an SSA value denoting new(typ).
   850  func (s *state) newObject(typ *types.Type) *ssa.Value {
   851  	if typ.Size() == 0 {
   852  		return s.newValue1A(ssa.OpAddr, types.NewPtr(typ), ir.Syms.Zerobase, s.sb)
   853  	}
   854  	rtype := s.reflectType(typ)
   855  	if specialMallocSym := s.specializedMallocSym(typ.Size(), typ.HasPointers()); specialMallocSym != nil {
   856  		return s.rtcall(specialMallocSym, true, []*types.Type{types.NewPtr(typ)},
   857  			s.constInt(types.Types[types.TUINTPTR], typ.Size()),
   858  			rtype,
   859  			s.constBool(true),
   860  		)[0]
   861  	}
   862  	return s.rtcall(ir.Syms.Newobject, true, []*types.Type{types.NewPtr(typ)}, rtype)[0]
   863  }
   864  
   865  // newObjectNonSpecialized returns an SSA value denoting new(typ). It does
   866  // not produce size-specialized malloc functions.
   867  func (s *state) newObjectNonSpecialized(typ *types.Type, rtype *ssa.Value) *ssa.Value {
   868  	if typ.Size() == 0 {
   869  		return s.newValue1A(ssa.OpAddr, types.NewPtr(typ), ir.Syms.Zerobase, s.sb)
   870  	}
   871  	if rtype == nil {
   872  		rtype = s.reflectType(typ)
   873  	}
   874  	return s.rtcall(ir.Syms.Newobject, true, []*types.Type{types.NewPtr(typ)}, rtype)[0]
   875  }
   876  
   877  func (s *state) checkPtrAlignment(n *ir.ConvExpr, v *ssa.Value, count *ssa.Value) {
   878  	if !n.Type().IsPtr() {
   879  		s.Fatalf("expected pointer type: %v", n.Type())
   880  	}
   881  	elem, rtypeExpr := n.Type().Elem(), n.ElemRType
   882  	if count != nil {
   883  		if !elem.IsArray() {
   884  			s.Fatalf("expected array type: %v", elem)
   885  		}
   886  		elem, rtypeExpr = elem.Elem(), n.ElemElemRType
   887  	}
   888  	size := elem.Size()
   889  	// Casting from larger type to smaller one is ok, so for smallest type, do nothing.
   890  	if elem.Alignment() == 1 && (size == 0 || size == 1 || count == nil) {
   891  		return
   892  	}
   893  	if count == nil {
   894  		count = s.constInt(types.Types[types.TUINTPTR], 1)
   895  	}
   896  	if count.Type.Size() != s.config.PtrSize {
   897  		s.Fatalf("expected count fit to a uintptr size, have: %d, want: %d", count.Type.Size(), s.config.PtrSize)
   898  	}
   899  	var rtype *ssa.Value
   900  	if rtypeExpr != nil {
   901  		rtype = s.expr(rtypeExpr)
   902  	} else {
   903  		rtype = s.reflectType(elem)
   904  	}
   905  	s.rtcall(ir.Syms.CheckPtrAlignment, true, nil, v, rtype, count)
   906  }
   907  
   908  // reflectType returns an SSA value representing a pointer to typ's
   909  // reflection type descriptor.
   910  func (s *state) reflectType(typ *types.Type) *ssa.Value {
   911  	// TODO(mdempsky): Make this Fatalf under Unified IR; frontend needs
   912  	// to supply RType expressions.
   913  	lsym := reflectdata.TypeLinksym(typ)
   914  	return s.entryNewValue1A(ssa.OpAddr, types.NewPtr(types.Types[types.TUINT8]), lsym, s.sb)
   915  }
   916  
   917  func dumpSourcesColumn(writer *ssa.HTMLWriter, fn *ir.Func) {
   918  	// Read sources of target function fn.
   919  	fname := base.Ctxt.PosTable.Pos(fn.Pos()).Filename()
   920  	targetFn, err := readFuncLines(fname, fn.Pos().Line(), fn.Endlineno.Line())
   921  	if err != nil {
   922  		writer.Logf("cannot read sources for function %v: %v", fn, err)
   923  	}
   924  
   925  	// Read sources of inlined functions.
   926  	var inlFns []*ssa.FuncLines
   927  	for _, fi := range ssaDumpInlined {
   928  		elno := fi.Endlineno
   929  		fname := base.Ctxt.PosTable.Pos(fi.Pos()).Filename()
   930  		fnLines, err := readFuncLines(fname, fi.Pos().Line(), elno.Line())
   931  		if err != nil {
   932  			writer.Logf("cannot read sources for inlined function %v: %v", fi, err)
   933  			continue
   934  		}
   935  		inlFns = append(inlFns, fnLines)
   936  	}
   937  
   938  	slices.SortFunc(inlFns, ssa.ByTopoCmp)
   939  	if targetFn != nil {
   940  		inlFns = append([]*ssa.FuncLines{targetFn}, inlFns...)
   941  	}
   942  
   943  	writer.WriteSources("sources", inlFns)
   944  }
   945  
   946  func readFuncLines(file string, start, end uint) (*ssa.FuncLines, error) {
   947  	f, err := os.Open(os.ExpandEnv(file))
   948  	if err != nil {
   949  		return nil, err
   950  	}
   951  	defer f.Close()
   952  	var lines []string
   953  	ln := uint(1)
   954  	scanner := bufio.NewScanner(f)
   955  	for scanner.Scan() && ln <= end {
   956  		if ln >= start {
   957  			lines = append(lines, scanner.Text())
   958  		}
   959  		ln++
   960  	}
   961  	return &ssa.FuncLines{Filename: file, StartLineno: start, Lines: lines}, nil
   962  }
   963  
   964  // updateUnsetPredPos propagates the earliest-value position information for b
   965  // towards all of b's predecessors that need a position, and recurs on that
   966  // predecessor if its position is updated. B should have a non-empty position.
   967  func (s *state) updateUnsetPredPos(b *ssa.Block) {
   968  	if b.Pos == src.NoXPos {
   969  		s.Fatalf("Block %s should have a position", b)
   970  	}
   971  	bestPos := src.NoXPos
   972  	for _, e := range b.Preds {
   973  		p := e.Block()
   974  		if !p.LackingPos() {
   975  			continue
   976  		}
   977  		if bestPos == src.NoXPos {
   978  			bestPos = b.Pos
   979  			for _, v := range b.Values {
   980  				if v.LackingPos() {
   981  					continue
   982  				}
   983  				if v.Pos != src.NoXPos {
   984  					// Assume values are still in roughly textual order;
   985  					// TODO: could also seek minimum position?
   986  					bestPos = v.Pos
   987  					break
   988  				}
   989  			}
   990  		}
   991  		p.Pos = bestPos
   992  		s.updateUnsetPredPos(p) // We do not expect long chains of these, thus recursion is okay.
   993  	}
   994  }
   995  
   996  // Information about each open-coded defer.
   997  type openDeferInfo struct {
   998  	// The node representing the call of the defer
   999  	n *ir.CallExpr
  1000  	// If defer call is closure call, the address of the argtmp where the
  1001  	// closure is stored.
  1002  	closure *ssa.Value
  1003  	// The node representing the argtmp where the closure is stored - used for
  1004  	// function, method, or interface call, to store a closure that panic
  1005  	// processing can use for this defer.
  1006  	closureNode *ir.Name
  1007  }
  1008  
  1009  type state struct {
  1010  	// configuration (arch) information
  1011  	config *ssa.Config
  1012  
  1013  	// function we're building
  1014  	f *ssa.Func
  1015  
  1016  	// Node for function
  1017  	curfn *ir.Func
  1018  
  1019  	// labels in f
  1020  	labels map[string]*ssaLabel
  1021  
  1022  	// unlabeled break and continue statement tracking
  1023  	breakTo    *ssa.Block // current target for plain break statement
  1024  	continueTo *ssa.Block // current target for plain continue statement
  1025  
  1026  	// current location where we're interpreting the AST
  1027  	curBlock *ssa.Block
  1028  
  1029  	// variable assignments in the current block (map from variable symbol to ssa value)
  1030  	// *Node is the unique identifier (an ONAME Node) for the variable.
  1031  	// TODO: keep a single varnum map, then make all of these maps slices instead?
  1032  	vars map[ir.Node]*ssa.Value
  1033  
  1034  	// fwdVars are variables that are used before they are defined in the current block.
  1035  	// This map exists just to coalesce multiple references into a single FwdRef op.
  1036  	// *Node is the unique identifier (an ONAME Node) for the variable.
  1037  	fwdVars map[ir.Node]*ssa.Value
  1038  
  1039  	// all defined variables at the end of each block. Indexed by block ID.
  1040  	defvars []map[ir.Node]*ssa.Value
  1041  
  1042  	// addresses of PPARAM and PPARAMOUT variables on the stack.
  1043  	decladdrs map[*ir.Name]*ssa.Value
  1044  
  1045  	// starting values. Memory, stack pointer, and globals pointer
  1046  	startmem *ssa.Value
  1047  	sp       *ssa.Value
  1048  	sb       *ssa.Value
  1049  	// value representing address of where deferBits autotmp is stored
  1050  	deferBitsAddr *ssa.Value
  1051  	deferBitsTemp *ir.Name
  1052  
  1053  	// line number stack. The current line number is top of stack
  1054  	line []src.XPos
  1055  	// the last line number processed; it may have been popped
  1056  	lastPos src.XPos
  1057  
  1058  	// list of panic calls by function name and line number.
  1059  	// Used to deduplicate panic calls.
  1060  	panics map[funcLine]*ssa.Block
  1061  
  1062  	cgoUnsafeArgs       bool
  1063  	hasdefer            bool // whether the function contains a defer statement
  1064  	softFloat           bool
  1065  	hasOpenDefers       bool // whether we are doing open-coded defers
  1066  	checkPtrEnabled     bool // whether to insert checkptr instrumentation
  1067  	instrumentEnterExit bool // whether to instrument function enter/exit
  1068  	instrumentMemory    bool // whether to instrument memory operations
  1069  
  1070  	// If doing open-coded defers, list of info about the defer calls in
  1071  	// scanning order. Hence, at exit we should run these defers in reverse
  1072  	// order of this list
  1073  	openDefers []*openDeferInfo
  1074  	// For open-coded defers, this is the beginning and end blocks of the last
  1075  	// defer exit code that we have generated so far. We use these to share
  1076  	// code between exits if the shareDeferExits option (disabled by default)
  1077  	// is on.
  1078  	lastDeferExit       *ssa.Block // Entry block of last defer exit code we generated
  1079  	lastDeferFinalBlock *ssa.Block // Final block of last defer exit code we generated
  1080  	lastDeferCount      int        // Number of defers encountered at that point
  1081  
  1082  	prevCall *ssa.Value // the previous call; use this to tie results to the call op.
  1083  
  1084  	// List of allocations in the current block that are still pending.
  1085  	// They are all (OffPtr (Select0 (runtime call))) and have the correct types,
  1086  	// but the offsets are not set yet, and the type of the runtime call is also not final.
  1087  	pendingHeapAllocations []*ssa.Value
  1088  
  1089  	// First argument of append calls that could be stack allocated.
  1090  	appendTargets map[ir.Node]bool
  1091  
  1092  	// Block starting position, indexed by block id.
  1093  	blockStarts []src.XPos
  1094  }
  1095  
  1096  type funcLine struct {
  1097  	f    *obj.LSym
  1098  	base *src.PosBase
  1099  	line uint
  1100  }
  1101  
  1102  type ssaLabel struct {
  1103  	target         *ssa.Block // block identified by this label
  1104  	breakTarget    *ssa.Block // block to break to in control flow node identified by this label
  1105  	continueTarget *ssa.Block // block to continue to in control flow node identified by this label
  1106  }
  1107  
  1108  // label returns the label associated with sym, creating it if necessary.
  1109  func (s *state) label(sym *types.Sym) *ssaLabel {
  1110  	lab := s.labels[sym.Name]
  1111  	if lab == nil {
  1112  		lab = new(ssaLabel)
  1113  		s.labels[sym.Name] = lab
  1114  	}
  1115  	return lab
  1116  }
  1117  
  1118  func (s *state) Logf(msg string, args ...interface{}) { s.f.Logf(msg, args...) }
  1119  func (s *state) Log() bool                            { return s.f.Log() }
  1120  func (s *state) Fatalf(msg string, args ...interface{}) {
  1121  	s.f.Frontend().Fatalf(s.peekPos(), msg, args...)
  1122  }
  1123  func (s *state) Warnl(pos src.XPos, msg string, args ...interface{}) { s.f.Warnl(pos, msg, args...) }
  1124  func (s *state) Debug_checknil() bool                                { return s.f.Frontend().Debug_checknil() }
  1125  
  1126  func ssaMarker(name string) *ir.Name {
  1127  	return ir.NewNameAt(base.Pos, &types.Sym{Name: name}, nil)
  1128  }
  1129  
  1130  var (
  1131  	// marker node for the memory variable
  1132  	memVar = ssaMarker("mem")
  1133  
  1134  	// marker nodes for temporary variables
  1135  	ptrVar       = ssaMarker("ptr")
  1136  	lenVar       = ssaMarker("len")
  1137  	capVar       = ssaMarker("cap")
  1138  	typVar       = ssaMarker("typ")
  1139  	okVar        = ssaMarker("ok")
  1140  	deferBitsVar = ssaMarker("deferBits")
  1141  	hashVar      = ssaMarker("hash")
  1142  )
  1143  
  1144  // startBlock sets the current block we're generating code in to b.
  1145  func (s *state) startBlock(b *ssa.Block) {
  1146  	if s.curBlock != nil {
  1147  		s.Fatalf("starting block %v when block %v has not ended", b, s.curBlock)
  1148  	}
  1149  	s.curBlock = b
  1150  	s.vars = map[ir.Node]*ssa.Value{}
  1151  	clear(s.fwdVars)
  1152  	for len(s.blockStarts) <= int(b.ID) {
  1153  		s.blockStarts = append(s.blockStarts, src.NoXPos)
  1154  	}
  1155  }
  1156  
  1157  // endBlock marks the end of generating code for the current block.
  1158  // Returns the (former) current block. Returns nil if there is no current
  1159  // block, i.e. if no code flows to the current execution point.
  1160  func (s *state) endBlock() *ssa.Block {
  1161  	b := s.curBlock
  1162  	if b == nil {
  1163  		return nil
  1164  	}
  1165  
  1166  	s.flushPendingHeapAllocations()
  1167  
  1168  	for len(s.defvars) <= int(b.ID) {
  1169  		s.defvars = append(s.defvars, nil)
  1170  	}
  1171  	s.defvars[b.ID] = s.vars
  1172  	s.curBlock = nil
  1173  	s.vars = nil
  1174  	if b.LackingPos() {
  1175  		// Empty plain blocks get the line of their successor (handled after all blocks created),
  1176  		// except for increment blocks in For statements (handled in ssa conversion of OFOR),
  1177  		// and for blocks ending in GOTO/BREAK/CONTINUE.
  1178  		b.Pos = src.NoXPos
  1179  	} else {
  1180  		b.Pos = s.lastPos
  1181  		if s.blockStarts[b.ID] == src.NoXPos {
  1182  			s.blockStarts[b.ID] = s.lastPos
  1183  		}
  1184  	}
  1185  	return b
  1186  }
  1187  
  1188  // pushLine pushes a line number on the line number stack.
  1189  func (s *state) pushLine(line src.XPos) {
  1190  	if !line.IsKnown() {
  1191  		// the frontend may emit node with line number missing,
  1192  		// use the parent line number in this case.
  1193  		line = s.peekPos()
  1194  		if base.Flag.K != 0 {
  1195  			base.Warn("buildssa: unknown position (line 0)")
  1196  		}
  1197  	} else {
  1198  		s.lastPos = line
  1199  	}
  1200  	// The first position we see for a new block is its starting position
  1201  	// (the line number for its phis, if any).
  1202  	if b := s.curBlock; b != nil && s.blockStarts[b.ID] == src.NoXPos {
  1203  		s.blockStarts[b.ID] = line
  1204  	}
  1205  
  1206  	s.line = append(s.line, line)
  1207  }
  1208  
  1209  // popLine pops the top of the line number stack.
  1210  func (s *state) popLine() {
  1211  	s.line = s.line[:len(s.line)-1]
  1212  }
  1213  
  1214  // peekPos peeks the top of the line number stack.
  1215  func (s *state) peekPos() src.XPos {
  1216  	return s.line[len(s.line)-1]
  1217  }
  1218  
  1219  // newValue0 adds a new value with no arguments to the current block.
  1220  func (s *state) newValue0(op ssa.Op, t *types.Type) *ssa.Value {
  1221  	return s.curBlock.NewValue0(s.peekPos(), op, t)
  1222  }
  1223  
  1224  // newValue0A adds a new value with no arguments and an aux value to the current block.
  1225  func (s *state) newValue0A(op ssa.Op, t *types.Type, aux ssa.Aux) *ssa.Value {
  1226  	return s.curBlock.NewValue0A(s.peekPos(), op, t, aux)
  1227  }
  1228  
  1229  // newValue0I adds a new value with no arguments and an auxint value to the current block.
  1230  func (s *state) newValue0I(op ssa.Op, t *types.Type, auxint int64) *ssa.Value {
  1231  	return s.curBlock.NewValue0I(s.peekPos(), op, t, auxint)
  1232  }
  1233  
  1234  // newValue1 adds a new value with one argument to the current block.
  1235  func (s *state) newValue1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1236  	return s.curBlock.NewValue1(s.peekPos(), op, t, arg)
  1237  }
  1238  
  1239  // newValue1A adds a new value with one argument and an aux value to the current block.
  1240  func (s *state) newValue1A(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value) *ssa.Value {
  1241  	return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
  1242  }
  1243  
  1244  // newValue1Apos adds a new value with one argument and an aux value to the current block.
  1245  // isStmt determines whether the created values may be a statement or not
  1246  // (i.e., false means never, yes means maybe).
  1247  func (s *state) newValue1Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value, isStmt bool) *ssa.Value {
  1248  	if isStmt {
  1249  		return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
  1250  	}
  1251  	return s.curBlock.NewValue1A(s.peekPos().WithNotStmt(), op, t, aux, arg)
  1252  }
  1253  
  1254  // newValue1I adds a new value with one argument and an auxint value to the current block.
  1255  func (s *state) newValue1I(op ssa.Op, t *types.Type, aux int64, arg *ssa.Value) *ssa.Value {
  1256  	return s.curBlock.NewValue1I(s.peekPos(), op, t, aux, arg)
  1257  }
  1258  
  1259  // newValue2 adds a new value with two arguments to the current block.
  1260  func (s *state) newValue2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1261  	return s.curBlock.NewValue2(s.peekPos(), op, t, arg0, arg1)
  1262  }
  1263  
  1264  // newValue2A adds a new value with two arguments and an aux value to the current block.
  1265  func (s *state) newValue2A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value) *ssa.Value {
  1266  	return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
  1267  }
  1268  
  1269  // newValue2Apos adds a new value with two arguments and an aux value to the current block.
  1270  // isStmt determines whether the created values may be a statement or not
  1271  // (i.e., false means never, yes means maybe).
  1272  func (s *state) newValue2Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value, isStmt bool) *ssa.Value {
  1273  	if isStmt {
  1274  		return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
  1275  	}
  1276  	return s.curBlock.NewValue2A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1)
  1277  }
  1278  
  1279  // newValue2I adds a new value with two arguments and an auxint value to the current block.
  1280  func (s *state) newValue2I(op ssa.Op, t *types.Type, aux int64, arg0, arg1 *ssa.Value) *ssa.Value {
  1281  	return s.curBlock.NewValue2I(s.peekPos(), op, t, aux, arg0, arg1)
  1282  }
  1283  
  1284  // newValue3 adds a new value with three arguments to the current block.
  1285  func (s *state) newValue3(op ssa.Op, t *types.Type, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1286  	return s.curBlock.NewValue3(s.peekPos(), op, t, arg0, arg1, arg2)
  1287  }
  1288  
  1289  // newValue3I adds a new value with three arguments and an auxint value to the current block.
  1290  func (s *state) newValue3I(op ssa.Op, t *types.Type, aux int64, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1291  	return s.curBlock.NewValue3I(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1292  }
  1293  
  1294  // newValue3A adds a new value with three arguments and an aux value to the current block.
  1295  func (s *state) newValue3A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1296  	return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1297  }
  1298  
  1299  // newValue3Apos adds a new value with three arguments and an aux value to the current block.
  1300  // isStmt determines whether the created values may be a statement or not
  1301  // (i.e., false means never, yes means maybe).
  1302  func (s *state) newValue3Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1, arg2 *ssa.Value, isStmt bool) *ssa.Value {
  1303  	if isStmt {
  1304  		return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1305  	}
  1306  	return s.curBlock.NewValue3A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1, arg2)
  1307  }
  1308  
  1309  // newValue4 adds a new value with four arguments to the current block.
  1310  func (s *state) newValue4(op ssa.Op, t *types.Type, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
  1311  	return s.curBlock.NewValue4(s.peekPos(), op, t, arg0, arg1, arg2, arg3)
  1312  }
  1313  
  1314  // newValue4I adds a new value with four arguments and an auxint value to the current block.
  1315  func (s *state) newValue4I(op ssa.Op, t *types.Type, aux int64, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
  1316  	return s.curBlock.NewValue4I(s.peekPos(), op, t, aux, arg0, arg1, arg2, arg3)
  1317  }
  1318  
  1319  func (s *state) entryBlock() *ssa.Block {
  1320  	b := s.f.Entry
  1321  	if base.Flag.N > 0 && s.curBlock != nil {
  1322  		// If optimizations are off, allocate in current block instead. Since with -N
  1323  		// we're not doing the CSE or tighten passes, putting lots of stuff in the
  1324  		// entry block leads to O(n^2) entries in the live value map during regalloc.
  1325  		// See issue 45897.
  1326  		b = s.curBlock
  1327  	}
  1328  	return b
  1329  }
  1330  
  1331  // entryNewValue0 adds a new value with no arguments to the entry block.
  1332  func (s *state) entryNewValue0(op ssa.Op, t *types.Type) *ssa.Value {
  1333  	return s.entryBlock().NewValue0(src.NoXPos, op, t)
  1334  }
  1335  
  1336  // entryNewValue0A adds a new value with no arguments and an aux value to the entry block.
  1337  func (s *state) entryNewValue0A(op ssa.Op, t *types.Type, aux ssa.Aux) *ssa.Value {
  1338  	return s.entryBlock().NewValue0A(src.NoXPos, op, t, aux)
  1339  }
  1340  
  1341  // entryNewValue1 adds a new value with one argument to the entry block.
  1342  func (s *state) entryNewValue1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1343  	return s.entryBlock().NewValue1(src.NoXPos, op, t, arg)
  1344  }
  1345  
  1346  // entryNewValue1I adds a new value with one argument and an auxint value to the entry block.
  1347  func (s *state) entryNewValue1I(op ssa.Op, t *types.Type, auxint int64, arg *ssa.Value) *ssa.Value {
  1348  	return s.entryBlock().NewValue1I(src.NoXPos, op, t, auxint, arg)
  1349  }
  1350  
  1351  // entryNewValue1A adds a new value with one argument and an aux value to the entry block.
  1352  func (s *state) entryNewValue1A(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value) *ssa.Value {
  1353  	return s.entryBlock().NewValue1A(src.NoXPos, op, t, aux, arg)
  1354  }
  1355  
  1356  // entryNewValue2 adds a new value with two arguments to the entry block.
  1357  func (s *state) entryNewValue2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1358  	return s.entryBlock().NewValue2(src.NoXPos, op, t, arg0, arg1)
  1359  }
  1360  
  1361  // entryNewValue2A adds a new value with two arguments and an aux value to the entry block.
  1362  func (s *state) entryNewValue2A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value) *ssa.Value {
  1363  	return s.entryBlock().NewValue2A(src.NoXPos, op, t, aux, arg0, arg1)
  1364  }
  1365  
  1366  // const* routines add a new const value to the entry block.
  1367  func (s *state) constSlice(t *types.Type) *ssa.Value {
  1368  	return s.f.ConstSlice(t)
  1369  }
  1370  func (s *state) constInterface(t *types.Type) *ssa.Value {
  1371  	return s.f.ConstInterface(t)
  1372  }
  1373  func (s *state) constNil(t *types.Type) *ssa.Value { return s.f.ConstNil(t) }
  1374  func (s *state) constEmptyString(t *types.Type) *ssa.Value {
  1375  	return s.f.ConstEmptyString(t)
  1376  }
  1377  func (s *state) constBool(c bool) *ssa.Value {
  1378  	return s.f.ConstBool(types.Types[types.TBOOL], c)
  1379  }
  1380  func (s *state) constInt8(t *types.Type, c int8) *ssa.Value {
  1381  	return s.f.ConstInt8(t, c)
  1382  }
  1383  func (s *state) constInt16(t *types.Type, c int16) *ssa.Value {
  1384  	return s.f.ConstInt16(t, c)
  1385  }
  1386  func (s *state) constInt32(t *types.Type, c int32) *ssa.Value {
  1387  	return s.f.ConstInt32(t, c)
  1388  }
  1389  func (s *state) constInt64(t *types.Type, c int64) *ssa.Value {
  1390  	return s.f.ConstInt64(t, c)
  1391  }
  1392  func (s *state) constFloat32(t *types.Type, c float64) *ssa.Value {
  1393  	return s.f.ConstFloat32(t, c)
  1394  }
  1395  func (s *state) constFloat64(t *types.Type, c float64) *ssa.Value {
  1396  	return s.f.ConstFloat64(t, c)
  1397  }
  1398  func (s *state) constInt(t *types.Type, c int64) *ssa.Value {
  1399  	if s.config.PtrSize == 8 {
  1400  		return s.constInt64(t, c)
  1401  	}
  1402  	if int64(int32(c)) != c {
  1403  		s.Fatalf("integer constant too big %d", c)
  1404  	}
  1405  	return s.constInt32(t, int32(c))
  1406  }
  1407  
  1408  // newValueOrSfCall* are wrappers around newValue*, which may create a call to a
  1409  // soft-float runtime function instead (when emitting soft-float code).
  1410  func (s *state) newValueOrSfCall1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1411  	if s.softFloat {
  1412  		if c, ok := s.sfcall(op, arg); ok {
  1413  			return c
  1414  		}
  1415  	}
  1416  	return s.newValue1(op, t, arg)
  1417  }
  1418  func (s *state) newValueOrSfCall2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1419  	if s.softFloat {
  1420  		if c, ok := s.sfcall(op, arg0, arg1); ok {
  1421  			return c
  1422  		}
  1423  	}
  1424  	return s.newValue2(op, t, arg0, arg1)
  1425  }
  1426  
  1427  type instrumentKind uint8
  1428  
  1429  const (
  1430  	instrumentRead = iota
  1431  	instrumentWrite
  1432  	instrumentMove
  1433  )
  1434  
  1435  func (s *state) instrument(t *types.Type, addr *ssa.Value, kind instrumentKind) {
  1436  	s.instrument2(t, addr, nil, kind)
  1437  }
  1438  
  1439  // instrumentFields instruments a read/write operation on addr.
  1440  // If it is instrumenting for MSAN or ASAN and t is a struct type, it instruments
  1441  // operation for each field, instead of for the whole struct.
  1442  func (s *state) instrumentFields(t *types.Type, addr *ssa.Value, kind instrumentKind) {
  1443  	if !(base.Flag.MSan || base.Flag.ASan) || !t.IsStruct() {
  1444  		s.instrument(t, addr, kind)
  1445  		return
  1446  	}
  1447  	for _, f := range t.Fields() {
  1448  		if f.Sym.IsBlank() {
  1449  			continue
  1450  		}
  1451  		offptr := s.newValue1I(ssa.OpOffPtr, types.NewPtr(f.Type), f.Offset, addr)
  1452  		s.instrumentFields(f.Type, offptr, kind)
  1453  	}
  1454  }
  1455  
  1456  func (s *state) instrumentMove(t *types.Type, dst, src *ssa.Value) {
  1457  	if base.Flag.MSan {
  1458  		s.instrument2(t, dst, src, instrumentMove)
  1459  	} else {
  1460  		s.instrument(t, src, instrumentRead)
  1461  		s.instrument(t, dst, instrumentWrite)
  1462  	}
  1463  }
  1464  
  1465  func (s *state) instrument2(t *types.Type, addr, addr2 *ssa.Value, kind instrumentKind) {
  1466  	if !s.instrumentMemory {
  1467  		return
  1468  	}
  1469  
  1470  	w := t.Size()
  1471  	if w == 0 {
  1472  		return // can't race on zero-sized things
  1473  	}
  1474  
  1475  	if ssa.IsSanitizerSafeAddr(addr) {
  1476  		return
  1477  	}
  1478  
  1479  	var fn *obj.LSym
  1480  	needWidth := false
  1481  
  1482  	if addr2 != nil && kind != instrumentMove {
  1483  		panic("instrument2: non-nil addr2 for non-move instrumentation")
  1484  	}
  1485  
  1486  	if base.Flag.MSan {
  1487  		switch kind {
  1488  		case instrumentRead:
  1489  			fn = ir.Syms.Msanread
  1490  		case instrumentWrite:
  1491  			fn = ir.Syms.Msanwrite
  1492  		case instrumentMove:
  1493  			fn = ir.Syms.Msanmove
  1494  		default:
  1495  			panic("unreachable")
  1496  		}
  1497  		needWidth = true
  1498  	} else if base.Flag.Race && t.NumComponents(types.CountBlankFields) > 1 {
  1499  		// for composite objects we have to write every address
  1500  		// because a write might happen to any subobject.
  1501  		// composites with only one element don't have subobjects, though.
  1502  		switch kind {
  1503  		case instrumentRead:
  1504  			fn = ir.Syms.Racereadrange
  1505  		case instrumentWrite:
  1506  			fn = ir.Syms.Racewriterange
  1507  		default:
  1508  			panic("unreachable")
  1509  		}
  1510  		needWidth = true
  1511  	} else if base.Flag.Race {
  1512  		// for non-composite objects we can write just the start
  1513  		// address, as any write must write the first byte.
  1514  		switch kind {
  1515  		case instrumentRead:
  1516  			fn = ir.Syms.Raceread
  1517  		case instrumentWrite:
  1518  			fn = ir.Syms.Racewrite
  1519  		default:
  1520  			panic("unreachable")
  1521  		}
  1522  	} else if base.Flag.ASan {
  1523  		switch kind {
  1524  		case instrumentRead:
  1525  			fn = ir.Syms.Asanread
  1526  		case instrumentWrite:
  1527  			fn = ir.Syms.Asanwrite
  1528  		default:
  1529  			panic("unreachable")
  1530  		}
  1531  		needWidth = true
  1532  	} else {
  1533  		panic("unreachable")
  1534  	}
  1535  
  1536  	args := []*ssa.Value{addr}
  1537  	if addr2 != nil {
  1538  		args = append(args, addr2)
  1539  	}
  1540  	if needWidth {
  1541  		args = append(args, s.constInt(types.Types[types.TUINTPTR], w))
  1542  	}
  1543  	s.rtcall(fn, true, nil, args...)
  1544  }
  1545  
  1546  func (s *state) load(t *types.Type, src *ssa.Value) *ssa.Value {
  1547  	s.instrumentFields(t, src, instrumentRead)
  1548  	return s.rawLoad(t, src)
  1549  }
  1550  
  1551  func (s *state) rawLoad(t *types.Type, src *ssa.Value) *ssa.Value {
  1552  	return s.newValue2(ssa.OpLoad, t, src, s.mem())
  1553  }
  1554  
  1555  func (s *state) store(t *types.Type, dst, val *ssa.Value) {
  1556  	s.vars[memVar] = s.newValue3A(ssa.OpStore, types.TypeMem, t, dst, val, s.mem())
  1557  }
  1558  
  1559  func (s *state) zero(t *types.Type, dst *ssa.Value) {
  1560  	s.instrument(t, dst, instrumentWrite)
  1561  	store := s.newValue2I(ssa.OpZero, types.TypeMem, t.Size(), dst, s.mem())
  1562  	store.Aux = t
  1563  	s.vars[memVar] = store
  1564  }
  1565  
  1566  func (s *state) move(t *types.Type, dst, src *ssa.Value) {
  1567  	s.moveWhichMayOverlap(t, dst, src, false)
  1568  }
  1569  func (s *state) moveWhichMayOverlap(t *types.Type, dst, src *ssa.Value, mayOverlap bool) {
  1570  	s.instrumentMove(t, dst, src)
  1571  	if mayOverlap && t.IsArray() && t.NumElem() > 1 && !ssa.IsInlinableMemmove(dst, src, t.Size(), s.f.Config) {
  1572  		// Normally, when moving Go values of type T from one location to another,
  1573  		// we don't need to worry about partial overlaps. The two Ts must either be
  1574  		// in disjoint (nonoverlapping) memory or in exactly the same location.
  1575  		// There are 2 cases where this isn't true:
  1576  		//  1) Using unsafe you can arrange partial overlaps.
  1577  		//  2) Since Go 1.17, you can use a cast from a slice to a ptr-to-array.
  1578  		//     https://go.dev/ref/spec#Conversions_from_slice_to_array_pointer
  1579  		//     This feature can be used to construct partial overlaps of array types.
  1580  		//       var a [3]int
  1581  		//       p := (*[2]int)(a[:])
  1582  		//       q := (*[2]int)(a[1:])
  1583  		//       *p = *q
  1584  		// We don't care about solving 1. Or at least, we haven't historically
  1585  		// and no one has complained.
  1586  		// For 2, we need to ensure that if there might be partial overlap,
  1587  		// then we can't use OpMove; we must use memmove instead.
  1588  		// (memmove handles partial overlap by copying in the correct
  1589  		// direction. OpMove does not.)
  1590  		//
  1591  		// Note that we have to be careful here not to introduce a call when
  1592  		// we're marshaling arguments to a call or unmarshaling results from a call.
  1593  		// Cases where this is happening must pass mayOverlap to false.
  1594  		// (Currently this only happens when unmarshaling results of a call.)
  1595  		if t.HasPointers() {
  1596  			s.rtcall(ir.Syms.Typedmemmove, true, nil, s.reflectType(t), dst, src)
  1597  			// We would have otherwise implemented this move with straightline code,
  1598  			// including a write barrier. Pretend we issue a write barrier here,
  1599  			// so that the write barrier tests work. (Otherwise they'd need to know
  1600  			// the details of IsInlineableMemmove.)
  1601  			s.curfn.SetWBPos(s.peekPos())
  1602  		} else {
  1603  			s.rtcall(ir.Syms.Memmove, true, nil, dst, src, s.constInt(types.Types[types.TUINTPTR], t.Size()))
  1604  		}
  1605  		ssa.LogLargeCopy(s.f.Name, s.peekPos(), t.Size())
  1606  		return
  1607  	}
  1608  	store := s.newValue3I(ssa.OpMove, types.TypeMem, t.Size(), dst, src, s.mem())
  1609  	store.Aux = t
  1610  	s.vars[memVar] = store
  1611  }
  1612  
  1613  // stmtList converts the statement list n to SSA and adds it to s.
  1614  func (s *state) stmtList(l ir.Nodes) {
  1615  	for _, n := range l {
  1616  		s.stmt(n)
  1617  	}
  1618  }
  1619  
  1620  // stmt converts the statement n to SSA and adds it to s.
  1621  func (s *state) stmt(n ir.Node) {
  1622  	s.pushLine(n.Pos())
  1623  	defer s.popLine()
  1624  
  1625  	// If s.curBlock is nil, and n isn't a label (which might have an associated goto somewhere),
  1626  	// then this code is dead. Stop here.
  1627  	if s.curBlock == nil && n.Op() != ir.OLABEL {
  1628  		return
  1629  	}
  1630  
  1631  	s.stmtList(n.Init())
  1632  	switch n.Op() {
  1633  
  1634  	case ir.OBLOCK:
  1635  		n := n.(*ir.BlockStmt)
  1636  		s.stmtList(n.List)
  1637  
  1638  	case ir.OFALL: // no-op
  1639  
  1640  	// Expression statements
  1641  	case ir.OCALLFUNC:
  1642  		n := n.(*ir.CallExpr)
  1643  		if ir.IsIntrinsicCall(n) {
  1644  			s.intrinsicCall(n)
  1645  			return
  1646  		}
  1647  		fallthrough
  1648  
  1649  	case ir.OCALLINTER:
  1650  		n := n.(*ir.CallExpr)
  1651  		s.callResult(n, callNormal)
  1652  		if n.Op() == ir.OCALLFUNC && n.Fun.Op() == ir.ONAME && n.Fun.(*ir.Name).Class == ir.PFUNC {
  1653  			if fn := n.Fun.Sym().Name; base.Flag.CompilingRuntime && fn == "throw" ||
  1654  				n.Fun.Sym().Pkg == ir.Pkgs.Runtime &&
  1655  					(fn == "throwinit" || fn == "gopanic" || fn == "panicwrap" || fn == "block" ||
  1656  						fn == "panicmakeslicelen" || fn == "panicmakeslicecap" || fn == "panicunsafeslicelen" ||
  1657  						fn == "panicunsafeslicenilptr" || fn == "panicunsafestringlen" || fn == "panicunsafestringnilptr" ||
  1658  						fn == "panicrangestate") {
  1659  				m := s.mem()
  1660  				b := s.endBlock()
  1661  				b.Kind = ssa.BlockExit
  1662  				b.SetControl(m)
  1663  				// TODO: never rewrite OPANIC to OCALLFUNC in the
  1664  				// first place. Need to wait until all backends
  1665  				// go through SSA.
  1666  			}
  1667  		}
  1668  	case ir.ODEFER:
  1669  		n := n.(*ir.GoDeferStmt)
  1670  		if base.Debug.Defer > 0 {
  1671  			var defertype string
  1672  			if s.hasOpenDefers {
  1673  				defertype = "open-coded"
  1674  			} else if n.Esc() == ir.EscNever {
  1675  				defertype = "stack-allocated"
  1676  			} else {
  1677  				defertype = "heap-allocated"
  1678  			}
  1679  			base.WarnfAt(n.Pos(), "%s defer", defertype)
  1680  		}
  1681  		if s.hasOpenDefers {
  1682  			s.openDeferRecord(n.Call.(*ir.CallExpr))
  1683  		} else {
  1684  			d := callDefer
  1685  			if n.Esc() == ir.EscNever && n.DeferAt == nil {
  1686  				d = callDeferStack
  1687  			}
  1688  			s.call(n.Call.(*ir.CallExpr), d, false, n.DeferAt)
  1689  		}
  1690  	case ir.OGO:
  1691  		n := n.(*ir.GoDeferStmt)
  1692  		s.callResult(n.Call.(*ir.CallExpr), callGo)
  1693  
  1694  	case ir.OAS2DOTTYPE:
  1695  		n := n.(*ir.AssignListStmt)
  1696  		var res, resok *ssa.Value
  1697  		if n.Rhs[0].Op() == ir.ODOTTYPE2 {
  1698  			res, resok = s.dottype(n.Rhs[0].(*ir.TypeAssertExpr), true)
  1699  		} else {
  1700  			res, resok = s.dynamicDottype(n.Rhs[0].(*ir.DynamicTypeAssertExpr), true)
  1701  		}
  1702  		deref := false
  1703  		if !ssa.CanSSA(n.Rhs[0].Type()) {
  1704  			if res.Op != ssa.OpLoad {
  1705  				s.Fatalf("dottype of non-load")
  1706  			}
  1707  			mem := s.mem()
  1708  			if res.Args[1] != mem {
  1709  				s.Fatalf("memory no longer live from 2-result dottype load")
  1710  			}
  1711  			deref = true
  1712  			res = res.Args[0]
  1713  		}
  1714  		s.assign(n.Lhs[0], res, deref, 0)
  1715  		s.assign(n.Lhs[1], resok, false, 0)
  1716  		return
  1717  
  1718  	case ir.OAS2FUNC:
  1719  		// We come here only when it is an intrinsic call returning two values.
  1720  		n := n.(*ir.AssignListStmt)
  1721  		call := n.Rhs[0].(*ir.CallExpr)
  1722  		if !ir.IsIntrinsicCall(call) {
  1723  			s.Fatalf("non-intrinsic AS2FUNC not expanded %v", call)
  1724  		}
  1725  		v := s.intrinsicCall(call)
  1726  		v1 := s.newValue1(ssa.OpSelect0, n.Lhs[0].Type(), v)
  1727  		v2 := s.newValue1(ssa.OpSelect1, n.Lhs[1].Type(), v)
  1728  		s.assign(n.Lhs[0], v1, false, 0)
  1729  		s.assign(n.Lhs[1], v2, false, 0)
  1730  		return
  1731  
  1732  	case ir.ODCL:
  1733  		n := n.(*ir.Decl)
  1734  		if v := n.X; v.Esc() == ir.EscHeap {
  1735  			s.newHeapaddr(v)
  1736  		}
  1737  
  1738  	case ir.OLABEL:
  1739  		n := n.(*ir.LabelStmt)
  1740  		sym := n.Label
  1741  		if sym.IsBlank() {
  1742  			// Nothing to do because the label isn't targetable. See issue 52278.
  1743  			break
  1744  		}
  1745  		lab := s.label(sym)
  1746  
  1747  		// The label might already have a target block via a goto.
  1748  		if lab.target == nil {
  1749  			lab.target = s.f.NewBlock(ssa.BlockPlain)
  1750  		}
  1751  
  1752  		// Go to that label.
  1753  		// (We pretend "label:" is preceded by "goto label", unless the predecessor is unreachable.)
  1754  		if s.curBlock != nil {
  1755  			b := s.endBlock()
  1756  			b.AddEdgeTo(lab.target)
  1757  		}
  1758  		s.startBlock(lab.target)
  1759  
  1760  	case ir.OGOTO:
  1761  		n := n.(*ir.BranchStmt)
  1762  		sym := n.Label
  1763  
  1764  		lab := s.label(sym)
  1765  		if lab.target == nil {
  1766  			lab.target = s.f.NewBlock(ssa.BlockPlain)
  1767  		}
  1768  
  1769  		b := s.endBlock()
  1770  		b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
  1771  		b.AddEdgeTo(lab.target)
  1772  
  1773  	case ir.OAS:
  1774  		n := n.(*ir.AssignStmt)
  1775  		if n.X == n.Y && n.X.Op() == ir.ONAME {
  1776  			// An x=x assignment. No point in doing anything
  1777  			// here. In addition, skipping this assignment
  1778  			// prevents generating:
  1779  			//   VARDEF x
  1780  			//   COPY x -> x
  1781  			// which is bad because x is incorrectly considered
  1782  			// dead before the vardef. See issue #14904.
  1783  			return
  1784  		}
  1785  
  1786  		// mayOverlap keeps track of whether the LHS and RHS might
  1787  		// refer to partially overlapping memory. Partial overlapping can
  1788  		// only happen for arrays, see the comment in moveWhichMayOverlap.
  1789  		//
  1790  		// If both sides of the assignment are not dereferences, then partial
  1791  		// overlap can't happen. Partial overlap can only occur only when the
  1792  		// arrays referenced are strictly smaller parts of the same base array.
  1793  		// If one side of the assignment is a full array, then partial overlap
  1794  		// can't happen. (The arrays are either disjoint or identical.)
  1795  		mayOverlap := n.X.Op() == ir.ODEREF && (n.Y != nil && n.Y.Op() == ir.ODEREF)
  1796  		if n.Y != nil && n.Y.Op() == ir.ODEREF {
  1797  			p := n.Y.(*ir.StarExpr).X
  1798  			for p.Op() == ir.OCONVNOP {
  1799  				p = p.(*ir.ConvExpr).X
  1800  			}
  1801  			if p.Op() == ir.OSPTR && p.(*ir.UnaryExpr).X.Type().IsString() {
  1802  				// Pointer fields of strings point to unmodifiable memory.
  1803  				// That memory can't overlap with the memory being written.
  1804  				mayOverlap = false
  1805  			}
  1806  		}
  1807  
  1808  		// Evaluate RHS.
  1809  		rhs := n.Y
  1810  		if rhs != nil {
  1811  			switch rhs.Op() {
  1812  			case ir.OSTRUCTLIT, ir.OARRAYLIT, ir.OSLICELIT:
  1813  				// All literals with nonzero fields have already been
  1814  				// rewritten during walk. Any that remain are just T{}
  1815  				// or equivalents. Use the zero value.
  1816  				if !ir.IsZero(rhs) {
  1817  					s.Fatalf("literal with nonzero value in SSA: %v", rhs)
  1818  				}
  1819  				rhs = nil
  1820  			case ir.OAPPEND:
  1821  				rhs := rhs.(*ir.CallExpr)
  1822  				// Check whether we're writing the result of an append back to the same slice.
  1823  				// If so, we handle it specially to avoid write barriers on the fast
  1824  				// (non-growth) path.
  1825  				if !ir.SameSafeExpr(n.X, rhs.Args[0]) || base.Flag.N != 0 {
  1826  					break
  1827  				}
  1828  				// If the slice can be SSA'd, it'll be on the stack,
  1829  				// so there will be no write barriers,
  1830  				// so there's no need to attempt to prevent them.
  1831  				if s.canSSA(n.X) {
  1832  					if base.Debug.Append > 0 { // replicating old diagnostic message
  1833  						base.WarnfAt(n.Pos(), "append: len-only update (in local slice)")
  1834  					}
  1835  					break
  1836  				}
  1837  				if base.Debug.Append > 0 {
  1838  					base.WarnfAt(n.Pos(), "append: len-only update")
  1839  				}
  1840  				s.append(rhs, true)
  1841  				return
  1842  			}
  1843  		}
  1844  
  1845  		if ir.IsBlank(n.X) {
  1846  			// _ = rhs
  1847  			// Just evaluate rhs for side-effects.
  1848  			if rhs != nil {
  1849  				s.expr(rhs)
  1850  			}
  1851  			return
  1852  		}
  1853  
  1854  		var t *types.Type
  1855  		if n.Y != nil {
  1856  			t = n.Y.Type()
  1857  		} else {
  1858  			t = n.X.Type()
  1859  		}
  1860  
  1861  		var r *ssa.Value
  1862  		deref := !ssa.CanSSA(t)
  1863  		if deref {
  1864  			if rhs == nil {
  1865  				r = nil // Signal assign to use OpZero.
  1866  			} else {
  1867  				r = s.addr(rhs)
  1868  			}
  1869  		} else {
  1870  			if rhs == nil {
  1871  				r = s.zeroVal(t)
  1872  			} else {
  1873  				r = s.expr(rhs)
  1874  			}
  1875  		}
  1876  
  1877  		var skip skipMask
  1878  		if rhs != nil && (rhs.Op() == ir.OSLICE || rhs.Op() == ir.OSLICE3 || rhs.Op() == ir.OSLICESTR) && ir.SameSafeExpr(rhs.(*ir.SliceExpr).X, n.X) {
  1879  			// We're assigning a slicing operation back to its source.
  1880  			// Don't write back fields we aren't changing. See issue #14855.
  1881  			rhs := rhs.(*ir.SliceExpr)
  1882  			i, j, k := rhs.Low, rhs.High, rhs.Max
  1883  			if i != nil && (i.Op() == ir.OLITERAL && i.Val().Kind() == constant.Int && ir.Int64Val(i) == 0) {
  1884  				// [0:...] is the same as [:...]
  1885  				i = nil
  1886  			}
  1887  			// TODO: detect defaults for len/cap also.
  1888  			// Currently doesn't really work because (*p)[:len(*p)] appears here as:
  1889  			//    tmp = len(*p)
  1890  			//    (*p)[:tmp]
  1891  			// if j != nil && (j.Op == OLEN && SameSafeExpr(j.Left, n.Left)) {
  1892  			//      j = nil
  1893  			// }
  1894  			// if k != nil && (k.Op == OCAP && SameSafeExpr(k.Left, n.Left)) {
  1895  			//      k = nil
  1896  			// }
  1897  			if i == nil {
  1898  				skip |= skipPtr
  1899  				if j == nil {
  1900  					skip |= skipLen
  1901  				}
  1902  				if k == nil {
  1903  					skip |= skipCap
  1904  				}
  1905  			}
  1906  		}
  1907  
  1908  		s.assignWhichMayOverlap(n.X, r, deref, skip, mayOverlap)
  1909  
  1910  	case ir.OIF:
  1911  		n := n.(*ir.IfStmt)
  1912  		if ir.IsConst(n.Cond, constant.Bool) {
  1913  			s.stmtList(n.Cond.Init())
  1914  			if ir.BoolVal(n.Cond) {
  1915  				s.stmtList(n.Body)
  1916  			} else {
  1917  				s.stmtList(n.Else)
  1918  			}
  1919  			break
  1920  		}
  1921  
  1922  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  1923  		var likely int8
  1924  		if n.Likely {
  1925  			likely = 1
  1926  		}
  1927  		var bThen *ssa.Block
  1928  		if len(n.Body) != 0 {
  1929  			bThen = s.f.NewBlock(ssa.BlockPlain)
  1930  		} else {
  1931  			bThen = bEnd
  1932  		}
  1933  		var bElse *ssa.Block
  1934  		if len(n.Else) != 0 {
  1935  			bElse = s.f.NewBlock(ssa.BlockPlain)
  1936  		} else {
  1937  			bElse = bEnd
  1938  		}
  1939  		s.condBranch(n.Cond, bThen, bElse, likely)
  1940  
  1941  		if len(n.Body) != 0 {
  1942  			s.startBlock(bThen)
  1943  			s.stmtList(n.Body)
  1944  			if b := s.endBlock(); b != nil {
  1945  				b.AddEdgeTo(bEnd)
  1946  			}
  1947  		}
  1948  		if len(n.Else) != 0 {
  1949  			s.startBlock(bElse)
  1950  			s.stmtList(n.Else)
  1951  			if b := s.endBlock(); b != nil {
  1952  				b.AddEdgeTo(bEnd)
  1953  			}
  1954  		}
  1955  		s.startBlock(bEnd)
  1956  
  1957  	case ir.ORETURN:
  1958  		n := n.(*ir.ReturnStmt)
  1959  		s.stmtList(n.Results)
  1960  		b := s.exit()
  1961  		b.Pos = s.lastPos.WithIsStmt()
  1962  
  1963  	case ir.OTAILCALL:
  1964  		n := n.(*ir.TailCallStmt)
  1965  		s.callResult(n.Call, callTail)
  1966  		call := s.mem()
  1967  		b := s.endBlock()
  1968  		b.Kind = ssa.BlockRetJmp // could use BlockExit. BlockRetJmp is mostly for clarity.
  1969  		b.SetControl(call)
  1970  
  1971  	case ir.OCONTINUE, ir.OBREAK:
  1972  		n := n.(*ir.BranchStmt)
  1973  		var to *ssa.Block
  1974  		if n.Label == nil {
  1975  			// plain break/continue
  1976  			switch n.Op() {
  1977  			case ir.OCONTINUE:
  1978  				to = s.continueTo
  1979  			case ir.OBREAK:
  1980  				to = s.breakTo
  1981  			}
  1982  		} else {
  1983  			// labeled break/continue; look up the target
  1984  			sym := n.Label
  1985  			lab := s.label(sym)
  1986  			switch n.Op() {
  1987  			case ir.OCONTINUE:
  1988  				to = lab.continueTarget
  1989  			case ir.OBREAK:
  1990  				to = lab.breakTarget
  1991  			}
  1992  		}
  1993  
  1994  		b := s.endBlock()
  1995  		b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
  1996  		b.AddEdgeTo(to)
  1997  
  1998  	case ir.OFOR:
  1999  		// OFOR: for Ninit; Left; Right { Nbody }
  2000  		// cond (Left); body (Nbody); incr (Right)
  2001  		n := n.(*ir.ForStmt)
  2002  		base.Assert(!n.DistinctVars) // Should all be rewritten before escape analysis
  2003  		bCond := s.f.NewBlock(ssa.BlockPlain)
  2004  		bBody := s.f.NewBlock(ssa.BlockPlain)
  2005  		bIncr := s.f.NewBlock(ssa.BlockPlain)
  2006  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  2007  
  2008  		// ensure empty for loops have correct position; issue #30167
  2009  		bBody.Pos = n.Pos()
  2010  
  2011  		// first, jump to condition test
  2012  		b := s.endBlock()
  2013  		b.AddEdgeTo(bCond)
  2014  
  2015  		// generate code to test condition
  2016  		s.startBlock(bCond)
  2017  		if n.Cond != nil {
  2018  			s.condBranch(n.Cond, bBody, bEnd, 1)
  2019  		} else {
  2020  			b := s.endBlock()
  2021  			b.Kind = ssa.BlockPlain
  2022  			b.AddEdgeTo(bBody)
  2023  		}
  2024  
  2025  		// set up for continue/break in body
  2026  		prevContinue := s.continueTo
  2027  		prevBreak := s.breakTo
  2028  		s.continueTo = bIncr
  2029  		s.breakTo = bEnd
  2030  		var lab *ssaLabel
  2031  		if sym := n.Label; sym != nil {
  2032  			// labeled for loop
  2033  			lab = s.label(sym)
  2034  			lab.continueTarget = bIncr
  2035  			lab.breakTarget = bEnd
  2036  		}
  2037  
  2038  		// generate body
  2039  		s.startBlock(bBody)
  2040  		s.stmtList(n.Body)
  2041  
  2042  		// tear down continue/break
  2043  		s.continueTo = prevContinue
  2044  		s.breakTo = prevBreak
  2045  		if lab != nil {
  2046  			lab.continueTarget = nil
  2047  			lab.breakTarget = nil
  2048  		}
  2049  
  2050  		// done with body, goto incr
  2051  		if b := s.endBlock(); b != nil {
  2052  			b.AddEdgeTo(bIncr)
  2053  		}
  2054  
  2055  		// generate incr
  2056  		s.startBlock(bIncr)
  2057  		if n.Post != nil {
  2058  			s.stmt(n.Post)
  2059  		}
  2060  		if b := s.endBlock(); b != nil {
  2061  			b.AddEdgeTo(bCond)
  2062  			// It can happen that bIncr ends in a block containing only VARKILL,
  2063  			// and that muddles the debugging experience.
  2064  			if b.Pos == src.NoXPos {
  2065  				b.Pos = bCond.Pos
  2066  			}
  2067  		}
  2068  
  2069  		s.startBlock(bEnd)
  2070  
  2071  	case ir.OSWITCH, ir.OSELECT:
  2072  		// These have been mostly rewritten by the front end into their Nbody fields.
  2073  		// Our main task is to correctly hook up any break statements.
  2074  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  2075  
  2076  		prevBreak := s.breakTo
  2077  		s.breakTo = bEnd
  2078  		var sym *types.Sym
  2079  		var body ir.Nodes
  2080  		if n.Op() == ir.OSWITCH {
  2081  			n := n.(*ir.SwitchStmt)
  2082  			sym = n.Label
  2083  			body = n.Compiled
  2084  		} else {
  2085  			n := n.(*ir.SelectStmt)
  2086  			sym = n.Label
  2087  			body = n.Compiled
  2088  		}
  2089  
  2090  		var lab *ssaLabel
  2091  		if sym != nil {
  2092  			// labeled
  2093  			lab = s.label(sym)
  2094  			lab.breakTarget = bEnd
  2095  		}
  2096  
  2097  		// generate body code
  2098  		s.stmtList(body)
  2099  
  2100  		s.breakTo = prevBreak
  2101  		if lab != nil {
  2102  			lab.breakTarget = nil
  2103  		}
  2104  
  2105  		// walk adds explicit OBREAK nodes to the end of all reachable code paths.
  2106  		// If we still have a current block here, then mark it unreachable.
  2107  		if s.curBlock != nil {
  2108  			m := s.mem()
  2109  			b := s.endBlock()
  2110  			b.Kind = ssa.BlockExit
  2111  			b.SetControl(m)
  2112  		}
  2113  		s.startBlock(bEnd)
  2114  
  2115  	case ir.OJUMPTABLE:
  2116  		n := n.(*ir.JumpTableStmt)
  2117  
  2118  		// Make blocks we'll need.
  2119  		jt := s.f.NewBlock(ssa.BlockJumpTable)
  2120  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  2121  
  2122  		// The only thing that needs evaluating is the index we're looking up.
  2123  		idx := s.expr(n.Idx)
  2124  		unsigned := idx.Type.IsUnsigned()
  2125  
  2126  		// Extend so we can do everything in uintptr arithmetic.
  2127  		t := types.Types[types.TUINTPTR]
  2128  		idx = s.conv(nil, idx, idx.Type, t)
  2129  
  2130  		// The ending condition for the current block decides whether we'll use
  2131  		// the jump table at all.
  2132  		// We check that min <= idx <= max and jump around the jump table
  2133  		// if that test fails.
  2134  		// We implement min <= idx <= max with 0 <= idx-min <= max-min, because
  2135  		// we'll need idx-min anyway as the control value for the jump table.
  2136  		var min, max uint64
  2137  		if unsigned {
  2138  			min, _ = constant.Uint64Val(n.Cases[0])
  2139  			max, _ = constant.Uint64Val(n.Cases[len(n.Cases)-1])
  2140  		} else {
  2141  			mn, _ := constant.Int64Val(n.Cases[0])
  2142  			mx, _ := constant.Int64Val(n.Cases[len(n.Cases)-1])
  2143  			min = uint64(mn)
  2144  			max = uint64(mx)
  2145  		}
  2146  		// Compare idx-min with max-min, to see if we can use the jump table.
  2147  		idx = s.newValue2(s.ssaOp(ir.OSUB, t), t, idx, s.uintptrConstant(min))
  2148  		width := s.uintptrConstant(max - min)
  2149  		cmp := s.newValue2(s.ssaOp(ir.OLE, t), types.Types[types.TBOOL], idx, width)
  2150  		b := s.endBlock()
  2151  		b.Kind = ssa.BlockIf
  2152  		b.SetControl(cmp)
  2153  		b.AddEdgeTo(jt)             // in range - use jump table
  2154  		b.AddEdgeTo(bEnd)           // out of range - no case in the jump table will trigger
  2155  		b.Likely = ssa.BranchLikely // TODO: assumes missing the table entirely is unlikely. True?
  2156  
  2157  		// Build jump table block.
  2158  		s.startBlock(jt)
  2159  		jt.Pos = n.Pos()
  2160  		if base.Flag.Cfg.SpectreIndex {
  2161  			idx = s.newValue2(ssa.OpSpectreSliceIndex, t, idx, width)
  2162  		}
  2163  		jt.SetControl(idx)
  2164  
  2165  		// Figure out where we should go for each index in the table.
  2166  		table := make([]*ssa.Block, max-min+1)
  2167  		for i := range table {
  2168  			table[i] = bEnd // default target
  2169  		}
  2170  		for i := range n.Targets {
  2171  			c := n.Cases[i]
  2172  			lab := s.label(n.Targets[i])
  2173  			if lab.target == nil {
  2174  				lab.target = s.f.NewBlock(ssa.BlockPlain)
  2175  			}
  2176  			var val uint64
  2177  			if unsigned {
  2178  				val, _ = constant.Uint64Val(c)
  2179  			} else {
  2180  				vl, _ := constant.Int64Val(c)
  2181  				val = uint64(vl)
  2182  			}
  2183  			// Overwrite the default target.
  2184  			table[val-min] = lab.target
  2185  		}
  2186  		for _, t := range table {
  2187  			jt.AddEdgeTo(t)
  2188  		}
  2189  		s.endBlock()
  2190  
  2191  		s.startBlock(bEnd)
  2192  
  2193  	case ir.OINTERFACESWITCH:
  2194  		n := n.(*ir.InterfaceSwitchStmt)
  2195  		typs := s.f.Config.Types
  2196  
  2197  		t := s.expr(n.RuntimeType)
  2198  		h := s.expr(n.Hash)
  2199  		d := s.newValue1A(ssa.OpAddr, typs.BytePtr, n.Descriptor, s.sb)
  2200  
  2201  		// Check the cache first.
  2202  		var merge *ssa.Block
  2203  		if base.Flag.N == 0 && rtabi.UseInterfaceSwitchCache(Arch.LinkArch.Family) {
  2204  			// Note: we can only use the cache if we have the right atomic load instruction.
  2205  			// Double-check that here.
  2206  			if intrinsics.lookup(Arch.LinkArch.Arch, "internal/runtime/atomic", "Loadp") == nil {
  2207  				s.Fatalf("atomic load not available")
  2208  			}
  2209  			merge = s.f.NewBlock(ssa.BlockPlain)
  2210  			cacheHit := s.f.NewBlock(ssa.BlockPlain)
  2211  			cacheMiss := s.f.NewBlock(ssa.BlockPlain)
  2212  			loopHead := s.f.NewBlock(ssa.BlockPlain)
  2213  			loopBody := s.f.NewBlock(ssa.BlockPlain)
  2214  
  2215  			// Pick right size ops.
  2216  			var mul, and, add, zext ssa.Op
  2217  			if s.config.PtrSize == 4 {
  2218  				mul = ssa.OpMul32
  2219  				and = ssa.OpAnd32
  2220  				add = ssa.OpAdd32
  2221  				zext = ssa.OpCopy
  2222  			} else {
  2223  				mul = ssa.OpMul64
  2224  				and = ssa.OpAnd64
  2225  				add = ssa.OpAdd64
  2226  				zext = ssa.OpZeroExt32to64
  2227  			}
  2228  
  2229  			// Load cache pointer out of descriptor, with an atomic load so
  2230  			// we ensure that we see a fully written cache.
  2231  			atomicLoad := s.newValue2(ssa.OpAtomicLoadPtr, types.NewTuple(typs.BytePtr, types.TypeMem), d, s.mem())
  2232  			cache := s.newValue1(ssa.OpSelect0, typs.BytePtr, atomicLoad)
  2233  			s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, atomicLoad)
  2234  
  2235  			// Initialize hash variable.
  2236  			s.vars[hashVar] = s.newValue1(zext, typs.Uintptr, h)
  2237  
  2238  			// Load mask from cache.
  2239  			mask := s.newValue2(ssa.OpLoad, typs.Uintptr, cache, s.mem())
  2240  			// Jump to loop head.
  2241  			b := s.endBlock()
  2242  			b.AddEdgeTo(loopHead)
  2243  
  2244  			// At loop head, get pointer to the cache entry.
  2245  			//   e := &cache.Entries[hash&mask]
  2246  			s.startBlock(loopHead)
  2247  			entries := s.newValue2(ssa.OpAddPtr, typs.UintptrPtr, cache, s.uintptrConstant(uint64(s.config.PtrSize)))
  2248  			idx := s.newValue2(and, typs.Uintptr, s.variable(hashVar, typs.Uintptr), mask)
  2249  			idx = s.newValue2(mul, typs.Uintptr, idx, s.uintptrConstant(uint64(3*s.config.PtrSize)))
  2250  			e := s.newValue2(ssa.OpAddPtr, typs.UintptrPtr, entries, idx)
  2251  			//   hash++
  2252  			s.vars[hashVar] = s.newValue2(add, typs.Uintptr, s.variable(hashVar, typs.Uintptr), s.uintptrConstant(1))
  2253  
  2254  			// Look for a cache hit.
  2255  			//   if e.Typ == t { goto hit }
  2256  			eTyp := s.newValue2(ssa.OpLoad, typs.Uintptr, e, s.mem())
  2257  			cmp1 := s.newValue2(ssa.OpEqPtr, typs.Bool, t, eTyp)
  2258  			b = s.endBlock()
  2259  			b.Kind = ssa.BlockIf
  2260  			b.SetControl(cmp1)
  2261  			b.AddEdgeTo(cacheHit)
  2262  			b.AddEdgeTo(loopBody)
  2263  
  2264  			// Look for an empty entry, the tombstone for this hash table.
  2265  			//   if e.Typ == nil { goto miss }
  2266  			s.startBlock(loopBody)
  2267  			cmp2 := s.newValue2(ssa.OpEqPtr, typs.Bool, eTyp, s.constNil(typs.BytePtr))
  2268  			b = s.endBlock()
  2269  			b.Kind = ssa.BlockIf
  2270  			b.SetControl(cmp2)
  2271  			b.AddEdgeTo(cacheMiss)
  2272  			b.AddEdgeTo(loopHead)
  2273  
  2274  			// On a hit, load the data fields of the cache entry.
  2275  			//   Case = e.Case
  2276  			//   Itab = e.Itab
  2277  			s.startBlock(cacheHit)
  2278  			eCase := s.newValue2(ssa.OpLoad, typs.Int, s.newValue1I(ssa.OpOffPtr, typs.IntPtr, s.config.PtrSize, e), s.mem())
  2279  			eItab := s.newValue2(ssa.OpLoad, typs.BytePtr, s.newValue1I(ssa.OpOffPtr, typs.BytePtrPtr, 2*s.config.PtrSize, e), s.mem())
  2280  			s.assign(n.Case, eCase, false, 0)
  2281  			s.assign(n.Itab, eItab, false, 0)
  2282  			b = s.endBlock()
  2283  			b.AddEdgeTo(merge)
  2284  
  2285  			// On a miss, call into the runtime to get the answer.
  2286  			s.startBlock(cacheMiss)
  2287  		}
  2288  
  2289  		r := s.rtcall(ir.Syms.InterfaceSwitch, true, []*types.Type{typs.Int, typs.BytePtr}, d, t)
  2290  		s.assign(n.Case, r[0], false, 0)
  2291  		s.assign(n.Itab, r[1], false, 0)
  2292  
  2293  		if merge != nil {
  2294  			// Cache hits merge in here.
  2295  			b := s.endBlock()
  2296  			b.Kind = ssa.BlockPlain
  2297  			b.AddEdgeTo(merge)
  2298  			s.startBlock(merge)
  2299  		}
  2300  
  2301  	case ir.OCHECKNIL:
  2302  		n := n.(*ir.UnaryExpr)
  2303  		p := s.expr(n.X)
  2304  		_ = s.nilCheck(p)
  2305  		// TODO: check that throwing away the nilcheck result is ok.
  2306  
  2307  	case ir.OINLMARK:
  2308  		n := n.(*ir.InlineMarkStmt)
  2309  		s.newValue1I(ssa.OpInlMark, types.TypeVoid, n.Index, s.mem())
  2310  
  2311  	default:
  2312  		s.Fatalf("unhandled stmt %v", n.Op())
  2313  	}
  2314  }
  2315  
  2316  // If true, share as many open-coded defer exits as possible (with the downside of
  2317  // worse line-number information)
  2318  const shareDeferExits = false
  2319  
  2320  // exit processes any code that needs to be generated just before returning.
  2321  // It returns a BlockRet block that ends the control flow. Its control value
  2322  // will be set to the final memory state.
  2323  func (s *state) exit() *ssa.Block {
  2324  	if s.hasdefer {
  2325  		if s.hasOpenDefers {
  2326  			if shareDeferExits && s.lastDeferExit != nil && len(s.openDefers) == s.lastDeferCount {
  2327  				if s.curBlock.Kind != ssa.BlockPlain {
  2328  					panic("Block for an exit should be BlockPlain")
  2329  				}
  2330  				s.curBlock.AddEdgeTo(s.lastDeferExit)
  2331  				s.endBlock()
  2332  				return s.lastDeferFinalBlock
  2333  			}
  2334  			s.openDeferExit()
  2335  		} else {
  2336  			// Shared deferreturn is assigned the "last" position in the function.
  2337  			// The linker picks the first deferreturn call it sees, so this is
  2338  			// the only sensible "shared" place.
  2339  			// To not-share deferreturn, the protocol would need to be changed
  2340  			// so that the call to deferproc-etc would receive the PC offset from
  2341  			// the return PC, and the runtime would need to use that instead of
  2342  			// the deferreturn retrieved from the pcln information.
  2343  			// opendefers would remain a problem, however.
  2344  			s.pushLine(s.curfn.Endlineno)
  2345  			s.rtcall(ir.Syms.Deferreturn, true, nil)
  2346  			s.popLine()
  2347  		}
  2348  	}
  2349  
  2350  	// Do actual return.
  2351  	// These currently turn into self-copies (in many cases).
  2352  	resultFields := s.curfn.Type().Results()
  2353  	results := make([]*ssa.Value, len(resultFields)+1, len(resultFields)+1)
  2354  	// Store SSAable and heap-escaped PPARAMOUT variables back to stack locations.
  2355  	for i, f := range resultFields {
  2356  		n := f.Nname.(*ir.Name)
  2357  		if s.canSSA(n) { // result is in some SSA variable
  2358  			if !n.IsOutputParamInRegisters() && n.Type().HasPointers() {
  2359  				// We are about to store to the result slot.
  2360  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
  2361  			}
  2362  			results[i] = s.variable(n, n.Type())
  2363  		} else if !n.OnStack() { // result is actually heap allocated
  2364  			// We are about to copy the in-heap result to the result slot.
  2365  			if n.Type().HasPointers() {
  2366  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
  2367  			}
  2368  			ha := s.expr(n.Heapaddr)
  2369  			s.instrumentFields(n.Type(), ha, instrumentRead)
  2370  			results[i] = s.newValue2(ssa.OpDereference, n.Type(), ha, s.mem())
  2371  		} else { // result is not SSA-able; not escaped, so not on heap, but too large for SSA.
  2372  			// Before register ABI this ought to be a self-move, home=dest,
  2373  			// With register ABI, it's still a self-move if parameter is on stack (i.e., too big or overflowed)
  2374  			// No VarDef, as the result slot is already holding live value.
  2375  			results[i] = s.newValue2(ssa.OpDereference, n.Type(), s.addr(n), s.mem())
  2376  		}
  2377  	}
  2378  
  2379  	// In -race mode, we need to call racefuncexit.
  2380  	// Note: This has to happen after we load any heap-allocated results,
  2381  	// otherwise races will be attributed to the caller instead.
  2382  	if s.instrumentEnterExit {
  2383  		s.rtcall(ir.Syms.Racefuncexit, true, nil)
  2384  	}
  2385  
  2386  	results[len(results)-1] = s.mem()
  2387  	m := s.newValue0(ssa.OpMakeResult, s.f.OwnAux.LateExpansionResultType())
  2388  	m.AddArgs(results...)
  2389  
  2390  	b := s.endBlock()
  2391  	b.Kind = ssa.BlockRet
  2392  	b.SetControl(m)
  2393  	if s.hasdefer && s.hasOpenDefers {
  2394  		s.lastDeferFinalBlock = b
  2395  	}
  2396  	return b
  2397  }
  2398  
  2399  type opAndType struct {
  2400  	op    ir.Op
  2401  	etype types.Kind
  2402  }
  2403  
  2404  var opToSSA = map[opAndType]ssa.Op{
  2405  	{ir.OADD, types.TINT8}:    ssa.OpAdd8,
  2406  	{ir.OADD, types.TUINT8}:   ssa.OpAdd8,
  2407  	{ir.OADD, types.TINT16}:   ssa.OpAdd16,
  2408  	{ir.OADD, types.TUINT16}:  ssa.OpAdd16,
  2409  	{ir.OADD, types.TINT32}:   ssa.OpAdd32,
  2410  	{ir.OADD, types.TUINT32}:  ssa.OpAdd32,
  2411  	{ir.OADD, types.TINT64}:   ssa.OpAdd64,
  2412  	{ir.OADD, types.TUINT64}:  ssa.OpAdd64,
  2413  	{ir.OADD, types.TFLOAT32}: ssa.OpAdd32F,
  2414  	{ir.OADD, types.TFLOAT64}: ssa.OpAdd64F,
  2415  
  2416  	{ir.OSUB, types.TINT8}:    ssa.OpSub8,
  2417  	{ir.OSUB, types.TUINT8}:   ssa.OpSub8,
  2418  	{ir.OSUB, types.TINT16}:   ssa.OpSub16,
  2419  	{ir.OSUB, types.TUINT16}:  ssa.OpSub16,
  2420  	{ir.OSUB, types.TINT32}:   ssa.OpSub32,
  2421  	{ir.OSUB, types.TUINT32}:  ssa.OpSub32,
  2422  	{ir.OSUB, types.TINT64}:   ssa.OpSub64,
  2423  	{ir.OSUB, types.TUINT64}:  ssa.OpSub64,
  2424  	{ir.OSUB, types.TFLOAT32}: ssa.OpSub32F,
  2425  	{ir.OSUB, types.TFLOAT64}: ssa.OpSub64F,
  2426  
  2427  	{ir.ONOT, types.TBOOL}: ssa.OpNot,
  2428  
  2429  	{ir.ONEG, types.TINT8}:    ssa.OpNeg8,
  2430  	{ir.ONEG, types.TUINT8}:   ssa.OpNeg8,
  2431  	{ir.ONEG, types.TINT16}:   ssa.OpNeg16,
  2432  	{ir.ONEG, types.TUINT16}:  ssa.OpNeg16,
  2433  	{ir.ONEG, types.TINT32}:   ssa.OpNeg32,
  2434  	{ir.ONEG, types.TUINT32}:  ssa.OpNeg32,
  2435  	{ir.ONEG, types.TINT64}:   ssa.OpNeg64,
  2436  	{ir.ONEG, types.TUINT64}:  ssa.OpNeg64,
  2437  	{ir.ONEG, types.TFLOAT32}: ssa.OpNeg32F,
  2438  	{ir.ONEG, types.TFLOAT64}: ssa.OpNeg64F,
  2439  
  2440  	{ir.OBITNOT, types.TINT8}:   ssa.OpCom8,
  2441  	{ir.OBITNOT, types.TUINT8}:  ssa.OpCom8,
  2442  	{ir.OBITNOT, types.TINT16}:  ssa.OpCom16,
  2443  	{ir.OBITNOT, types.TUINT16}: ssa.OpCom16,
  2444  	{ir.OBITNOT, types.TINT32}:  ssa.OpCom32,
  2445  	{ir.OBITNOT, types.TUINT32}: ssa.OpCom32,
  2446  	{ir.OBITNOT, types.TINT64}:  ssa.OpCom64,
  2447  	{ir.OBITNOT, types.TUINT64}: ssa.OpCom64,
  2448  
  2449  	{ir.OIMAG, types.TCOMPLEX64}:  ssa.OpComplexImag,
  2450  	{ir.OIMAG, types.TCOMPLEX128}: ssa.OpComplexImag,
  2451  	{ir.OREAL, types.TCOMPLEX64}:  ssa.OpComplexReal,
  2452  	{ir.OREAL, types.TCOMPLEX128}: ssa.OpComplexReal,
  2453  
  2454  	{ir.OMUL, types.TINT8}:    ssa.OpMul8,
  2455  	{ir.OMUL, types.TUINT8}:   ssa.OpMul8,
  2456  	{ir.OMUL, types.TINT16}:   ssa.OpMul16,
  2457  	{ir.OMUL, types.TUINT16}:  ssa.OpMul16,
  2458  	{ir.OMUL, types.TINT32}:   ssa.OpMul32,
  2459  	{ir.OMUL, types.TUINT32}:  ssa.OpMul32,
  2460  	{ir.OMUL, types.TINT64}:   ssa.OpMul64,
  2461  	{ir.OMUL, types.TUINT64}:  ssa.OpMul64,
  2462  	{ir.OMUL, types.TFLOAT32}: ssa.OpMul32F,
  2463  	{ir.OMUL, types.TFLOAT64}: ssa.OpMul64F,
  2464  
  2465  	{ir.ODIV, types.TFLOAT32}: ssa.OpDiv32F,
  2466  	{ir.ODIV, types.TFLOAT64}: ssa.OpDiv64F,
  2467  
  2468  	{ir.ODIV, types.TINT8}:   ssa.OpDiv8,
  2469  	{ir.ODIV, types.TUINT8}:  ssa.OpDiv8u,
  2470  	{ir.ODIV, types.TINT16}:  ssa.OpDiv16,
  2471  	{ir.ODIV, types.TUINT16}: ssa.OpDiv16u,
  2472  	{ir.ODIV, types.TINT32}:  ssa.OpDiv32,
  2473  	{ir.ODIV, types.TUINT32}: ssa.OpDiv32u,
  2474  	{ir.ODIV, types.TINT64}:  ssa.OpDiv64,
  2475  	{ir.ODIV, types.TUINT64}: ssa.OpDiv64u,
  2476  
  2477  	{ir.OMOD, types.TINT8}:   ssa.OpMod8,
  2478  	{ir.OMOD, types.TUINT8}:  ssa.OpMod8u,
  2479  	{ir.OMOD, types.TINT16}:  ssa.OpMod16,
  2480  	{ir.OMOD, types.TUINT16}: ssa.OpMod16u,
  2481  	{ir.OMOD, types.TINT32}:  ssa.OpMod32,
  2482  	{ir.OMOD, types.TUINT32}: ssa.OpMod32u,
  2483  	{ir.OMOD, types.TINT64}:  ssa.OpMod64,
  2484  	{ir.OMOD, types.TUINT64}: ssa.OpMod64u,
  2485  
  2486  	{ir.OAND, types.TINT8}:   ssa.OpAnd8,
  2487  	{ir.OAND, types.TUINT8}:  ssa.OpAnd8,
  2488  	{ir.OAND, types.TINT16}:  ssa.OpAnd16,
  2489  	{ir.OAND, types.TUINT16}: ssa.OpAnd16,
  2490  	{ir.OAND, types.TINT32}:  ssa.OpAnd32,
  2491  	{ir.OAND, types.TUINT32}: ssa.OpAnd32,
  2492  	{ir.OAND, types.TINT64}:  ssa.OpAnd64,
  2493  	{ir.OAND, types.TUINT64}: ssa.OpAnd64,
  2494  
  2495  	{ir.OOR, types.TINT8}:   ssa.OpOr8,
  2496  	{ir.OOR, types.TUINT8}:  ssa.OpOr8,
  2497  	{ir.OOR, types.TINT16}:  ssa.OpOr16,
  2498  	{ir.OOR, types.TUINT16}: ssa.OpOr16,
  2499  	{ir.OOR, types.TINT32}:  ssa.OpOr32,
  2500  	{ir.OOR, types.TUINT32}: ssa.OpOr32,
  2501  	{ir.OOR, types.TINT64}:  ssa.OpOr64,
  2502  	{ir.OOR, types.TUINT64}: ssa.OpOr64,
  2503  
  2504  	{ir.OXOR, types.TINT8}:   ssa.OpXor8,
  2505  	{ir.OXOR, types.TUINT8}:  ssa.OpXor8,
  2506  	{ir.OXOR, types.TINT16}:  ssa.OpXor16,
  2507  	{ir.OXOR, types.TUINT16}: ssa.OpXor16,
  2508  	{ir.OXOR, types.TINT32}:  ssa.OpXor32,
  2509  	{ir.OXOR, types.TUINT32}: ssa.OpXor32,
  2510  	{ir.OXOR, types.TINT64}:  ssa.OpXor64,
  2511  	{ir.OXOR, types.TUINT64}: ssa.OpXor64,
  2512  
  2513  	{ir.OEQ, types.TBOOL}:      ssa.OpEqB,
  2514  	{ir.OEQ, types.TINT8}:      ssa.OpEq8,
  2515  	{ir.OEQ, types.TUINT8}:     ssa.OpEq8,
  2516  	{ir.OEQ, types.TINT16}:     ssa.OpEq16,
  2517  	{ir.OEQ, types.TUINT16}:    ssa.OpEq16,
  2518  	{ir.OEQ, types.TINT32}:     ssa.OpEq32,
  2519  	{ir.OEQ, types.TUINT32}:    ssa.OpEq32,
  2520  	{ir.OEQ, types.TINT64}:     ssa.OpEq64,
  2521  	{ir.OEQ, types.TUINT64}:    ssa.OpEq64,
  2522  	{ir.OEQ, types.TINTER}:     ssa.OpEqInter,
  2523  	{ir.OEQ, types.TSLICE}:     ssa.OpEqSlice,
  2524  	{ir.OEQ, types.TFUNC}:      ssa.OpEqPtr,
  2525  	{ir.OEQ, types.TMAP}:       ssa.OpEqPtr,
  2526  	{ir.OEQ, types.TCHAN}:      ssa.OpEqPtr,
  2527  	{ir.OEQ, types.TPTR}:       ssa.OpEqPtr,
  2528  	{ir.OEQ, types.TUINTPTR}:   ssa.OpEqPtr,
  2529  	{ir.OEQ, types.TUNSAFEPTR}: ssa.OpEqPtr,
  2530  	{ir.OEQ, types.TFLOAT64}:   ssa.OpEq64F,
  2531  	{ir.OEQ, types.TFLOAT32}:   ssa.OpEq32F,
  2532  
  2533  	{ir.ONE, types.TBOOL}:      ssa.OpNeqB,
  2534  	{ir.ONE, types.TINT8}:      ssa.OpNeq8,
  2535  	{ir.ONE, types.TUINT8}:     ssa.OpNeq8,
  2536  	{ir.ONE, types.TINT16}:     ssa.OpNeq16,
  2537  	{ir.ONE, types.TUINT16}:    ssa.OpNeq16,
  2538  	{ir.ONE, types.TINT32}:     ssa.OpNeq32,
  2539  	{ir.ONE, types.TUINT32}:    ssa.OpNeq32,
  2540  	{ir.ONE, types.TINT64}:     ssa.OpNeq64,
  2541  	{ir.ONE, types.TUINT64}:    ssa.OpNeq64,
  2542  	{ir.ONE, types.TINTER}:     ssa.OpNeqInter,
  2543  	{ir.ONE, types.TSLICE}:     ssa.OpNeqSlice,
  2544  	{ir.ONE, types.TFUNC}:      ssa.OpNeqPtr,
  2545  	{ir.ONE, types.TMAP}:       ssa.OpNeqPtr,
  2546  	{ir.ONE, types.TCHAN}:      ssa.OpNeqPtr,
  2547  	{ir.ONE, types.TPTR}:       ssa.OpNeqPtr,
  2548  	{ir.ONE, types.TUINTPTR}:   ssa.OpNeqPtr,
  2549  	{ir.ONE, types.TUNSAFEPTR}: ssa.OpNeqPtr,
  2550  	{ir.ONE, types.TFLOAT64}:   ssa.OpNeq64F,
  2551  	{ir.ONE, types.TFLOAT32}:   ssa.OpNeq32F,
  2552  
  2553  	{ir.OLT, types.TINT8}:    ssa.OpLess8,
  2554  	{ir.OLT, types.TUINT8}:   ssa.OpLess8U,
  2555  	{ir.OLT, types.TINT16}:   ssa.OpLess16,
  2556  	{ir.OLT, types.TUINT16}:  ssa.OpLess16U,
  2557  	{ir.OLT, types.TINT32}:   ssa.OpLess32,
  2558  	{ir.OLT, types.TUINT32}:  ssa.OpLess32U,
  2559  	{ir.OLT, types.TINT64}:   ssa.OpLess64,
  2560  	{ir.OLT, types.TUINT64}:  ssa.OpLess64U,
  2561  	{ir.OLT, types.TFLOAT64}: ssa.OpLess64F,
  2562  	{ir.OLT, types.TFLOAT32}: ssa.OpLess32F,
  2563  
  2564  	{ir.OLE, types.TINT8}:    ssa.OpLeq8,
  2565  	{ir.OLE, types.TUINT8}:   ssa.OpLeq8U,
  2566  	{ir.OLE, types.TINT16}:   ssa.OpLeq16,
  2567  	{ir.OLE, types.TUINT16}:  ssa.OpLeq16U,
  2568  	{ir.OLE, types.TINT32}:   ssa.OpLeq32,
  2569  	{ir.OLE, types.TUINT32}:  ssa.OpLeq32U,
  2570  	{ir.OLE, types.TINT64}:   ssa.OpLeq64,
  2571  	{ir.OLE, types.TUINT64}:  ssa.OpLeq64U,
  2572  	{ir.OLE, types.TFLOAT64}: ssa.OpLeq64F,
  2573  	{ir.OLE, types.TFLOAT32}: ssa.OpLeq32F,
  2574  }
  2575  
  2576  func (s *state) concreteEtype(t *types.Type) types.Kind {
  2577  	e := t.Kind()
  2578  	switch e {
  2579  	default:
  2580  		return e
  2581  	case types.TINT:
  2582  		if s.config.PtrSize == 8 {
  2583  			return types.TINT64
  2584  		}
  2585  		return types.TINT32
  2586  	case types.TUINT:
  2587  		if s.config.PtrSize == 8 {
  2588  			return types.TUINT64
  2589  		}
  2590  		return types.TUINT32
  2591  	case types.TUINTPTR:
  2592  		if s.config.PtrSize == 8 {
  2593  			return types.TUINT64
  2594  		}
  2595  		return types.TUINT32
  2596  	}
  2597  }
  2598  
  2599  func (s *state) ssaOp(op ir.Op, t *types.Type) ssa.Op {
  2600  	etype := s.concreteEtype(t)
  2601  	x, ok := opToSSA[opAndType{op, etype}]
  2602  	if !ok {
  2603  		s.Fatalf("unhandled binary op %v %s", op, etype)
  2604  	}
  2605  	return x
  2606  }
  2607  
  2608  type opAndTwoTypes struct {
  2609  	op     ir.Op
  2610  	etype1 types.Kind
  2611  	etype2 types.Kind
  2612  }
  2613  
  2614  type twoTypes struct {
  2615  	etype1 types.Kind
  2616  	etype2 types.Kind
  2617  }
  2618  
  2619  type twoOpsAndType struct {
  2620  	op1              ssa.Op
  2621  	op2              ssa.Op
  2622  	intermediateType types.Kind
  2623  }
  2624  
  2625  var fpConvOpToSSA = map[twoTypes]twoOpsAndType{
  2626  
  2627  	{types.TINT8, types.TFLOAT32}:  {ssa.OpSignExt8to32, ssa.OpCvt32to32F, types.TINT32},
  2628  	{types.TINT16, types.TFLOAT32}: {ssa.OpSignExt16to32, ssa.OpCvt32to32F, types.TINT32},
  2629  	{types.TINT32, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt32to32F, types.TINT32},
  2630  	{types.TINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt64to32F, types.TINT64},
  2631  
  2632  	{types.TINT8, types.TFLOAT64}:  {ssa.OpSignExt8to32, ssa.OpCvt32to64F, types.TINT32},
  2633  	{types.TINT16, types.TFLOAT64}: {ssa.OpSignExt16to32, ssa.OpCvt32to64F, types.TINT32},
  2634  	{types.TINT32, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt32to64F, types.TINT32},
  2635  	{types.TINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt64to64F, types.TINT64},
  2636  
  2637  	{types.TFLOAT32, types.TINT8}:  {ssa.OpCvt32Fto32, ssa.OpTrunc32to8, types.TINT32},
  2638  	{types.TFLOAT32, types.TINT16}: {ssa.OpCvt32Fto32, ssa.OpTrunc32to16, types.TINT32},
  2639  	{types.TFLOAT32, types.TINT32}: {ssa.OpCvt32Fto32, ssa.OpCopy, types.TINT32},
  2640  	{types.TFLOAT32, types.TINT64}: {ssa.OpCvt32Fto64, ssa.OpCopy, types.TINT64},
  2641  
  2642  	{types.TFLOAT64, types.TINT8}:  {ssa.OpCvt64Fto32, ssa.OpTrunc32to8, types.TINT32},
  2643  	{types.TFLOAT64, types.TINT16}: {ssa.OpCvt64Fto32, ssa.OpTrunc32to16, types.TINT32},
  2644  	{types.TFLOAT64, types.TINT32}: {ssa.OpCvt64Fto32, ssa.OpCopy, types.TINT32},
  2645  	{types.TFLOAT64, types.TINT64}: {ssa.OpCvt64Fto64, ssa.OpCopy, types.TINT64},
  2646  	// unsigned
  2647  	{types.TUINT8, types.TFLOAT32}:  {ssa.OpZeroExt8to32, ssa.OpCvt32to32F, types.TINT32},
  2648  	{types.TUINT16, types.TFLOAT32}: {ssa.OpZeroExt16to32, ssa.OpCvt32to32F, types.TINT32},
  2649  	{types.TUINT32, types.TFLOAT32}: {ssa.OpZeroExt32to64, ssa.OpCvt64to32F, types.TINT64}, // go wide to dodge unsigned
  2650  	{types.TUINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpInvalid, types.TUINT64},            // Cvt64Uto32F, branchy code expansion instead
  2651  
  2652  	{types.TUINT8, types.TFLOAT64}:  {ssa.OpZeroExt8to32, ssa.OpCvt32to64F, types.TINT32},
  2653  	{types.TUINT16, types.TFLOAT64}: {ssa.OpZeroExt16to32, ssa.OpCvt32to64F, types.TINT32},
  2654  	{types.TUINT32, types.TFLOAT64}: {ssa.OpZeroExt32to64, ssa.OpCvt64to64F, types.TINT64}, // go wide to dodge unsigned
  2655  	{types.TUINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpInvalid, types.TUINT64},            // Cvt64Uto64F, branchy code expansion instead
  2656  
  2657  	{types.TFLOAT32, types.TUINT8}:  {ssa.OpCvt32Fto32, ssa.OpTrunc32to8, types.TINT32},
  2658  	{types.TFLOAT32, types.TUINT16}: {ssa.OpCvt32Fto32, ssa.OpTrunc32to16, types.TINT32},
  2659  	{types.TFLOAT32, types.TUINT32}: {ssa.OpInvalid, ssa.OpCopy, types.TINT64},  // Cvt64Fto32U, branchy code expansion instead
  2660  	{types.TFLOAT32, types.TUINT64}: {ssa.OpInvalid, ssa.OpCopy, types.TUINT64}, // Cvt32Fto64U, branchy code expansion instead
  2661  
  2662  	{types.TFLOAT64, types.TUINT8}:  {ssa.OpCvt64Fto32, ssa.OpTrunc32to8, types.TINT32},
  2663  	{types.TFLOAT64, types.TUINT16}: {ssa.OpCvt64Fto32, ssa.OpTrunc32to16, types.TINT32},
  2664  	{types.TFLOAT64, types.TUINT32}: {ssa.OpInvalid, ssa.OpCopy, types.TINT64},  // Cvt64Fto32U, branchy code expansion instead
  2665  	{types.TFLOAT64, types.TUINT64}: {ssa.OpInvalid, ssa.OpCopy, types.TUINT64}, // Cvt64Fto64U, branchy code expansion instead
  2666  
  2667  	// float
  2668  	{types.TFLOAT64, types.TFLOAT32}: {ssa.OpCvt64Fto32F, ssa.OpCopy, types.TFLOAT32},
  2669  	{types.TFLOAT64, types.TFLOAT64}: {ssa.OpRound64F, ssa.OpCopy, types.TFLOAT64},
  2670  	{types.TFLOAT32, types.TFLOAT32}: {ssa.OpRound32F, ssa.OpCopy, types.TFLOAT32},
  2671  	{types.TFLOAT32, types.TFLOAT64}: {ssa.OpCvt32Fto64F, ssa.OpCopy, types.TFLOAT64},
  2672  }
  2673  
  2674  // this map is used only for 32-bit arch, and only includes the difference
  2675  // on 32-bit arch, don't use int64<->float conversion for uint32
  2676  var fpConvOpToSSA32 = map[twoTypes]twoOpsAndType{
  2677  	{types.TUINT32, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt32Uto32F, types.TUINT32},
  2678  	{types.TUINT32, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt32Uto64F, types.TUINT32},
  2679  	{types.TFLOAT32, types.TUINT32}: {ssa.OpCvt32Fto32U, ssa.OpCopy, types.TUINT32},
  2680  	{types.TFLOAT64, types.TUINT32}: {ssa.OpCvt64Fto32U, ssa.OpCopy, types.TUINT32},
  2681  }
  2682  
  2683  // uint64<->float conversions, only on machines that have instructions for that
  2684  var uint64fpConvOpToSSA = map[twoTypes]twoOpsAndType{
  2685  	{types.TUINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt64Uto32F, types.TUINT64},
  2686  	{types.TUINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt64Uto64F, types.TUINT64},
  2687  	{types.TFLOAT32, types.TUINT64}: {ssa.OpCvt32Fto64U, ssa.OpCopy, types.TUINT64},
  2688  	{types.TFLOAT64, types.TUINT64}: {ssa.OpCvt64Fto64U, ssa.OpCopy, types.TUINT64},
  2689  }
  2690  
  2691  var shiftOpToSSA = map[opAndTwoTypes]ssa.Op{
  2692  	{ir.OLSH, types.TINT8, types.TUINT8}:   ssa.OpLsh8x8,
  2693  	{ir.OLSH, types.TUINT8, types.TUINT8}:  ssa.OpLsh8x8,
  2694  	{ir.OLSH, types.TINT8, types.TUINT16}:  ssa.OpLsh8x16,
  2695  	{ir.OLSH, types.TUINT8, types.TUINT16}: ssa.OpLsh8x16,
  2696  	{ir.OLSH, types.TINT8, types.TUINT32}:  ssa.OpLsh8x32,
  2697  	{ir.OLSH, types.TUINT8, types.TUINT32}: ssa.OpLsh8x32,
  2698  	{ir.OLSH, types.TINT8, types.TUINT64}:  ssa.OpLsh8x64,
  2699  	{ir.OLSH, types.TUINT8, types.TUINT64}: ssa.OpLsh8x64,
  2700  
  2701  	{ir.OLSH, types.TINT16, types.TUINT8}:   ssa.OpLsh16x8,
  2702  	{ir.OLSH, types.TUINT16, types.TUINT8}:  ssa.OpLsh16x8,
  2703  	{ir.OLSH, types.TINT16, types.TUINT16}:  ssa.OpLsh16x16,
  2704  	{ir.OLSH, types.TUINT16, types.TUINT16}: ssa.OpLsh16x16,
  2705  	{ir.OLSH, types.TINT16, types.TUINT32}:  ssa.OpLsh16x32,
  2706  	{ir.OLSH, types.TUINT16, types.TUINT32}: ssa.OpLsh16x32,
  2707  	{ir.OLSH, types.TINT16, types.TUINT64}:  ssa.OpLsh16x64,
  2708  	{ir.OLSH, types.TUINT16, types.TUINT64}: ssa.OpLsh16x64,
  2709  
  2710  	{ir.OLSH, types.TINT32, types.TUINT8}:   ssa.OpLsh32x8,
  2711  	{ir.OLSH, types.TUINT32, types.TUINT8}:  ssa.OpLsh32x8,
  2712  	{ir.OLSH, types.TINT32, types.TUINT16}:  ssa.OpLsh32x16,
  2713  	{ir.OLSH, types.TUINT32, types.TUINT16}: ssa.OpLsh32x16,
  2714  	{ir.OLSH, types.TINT32, types.TUINT32}:  ssa.OpLsh32x32,
  2715  	{ir.OLSH, types.TUINT32, types.TUINT32}: ssa.OpLsh32x32,
  2716  	{ir.OLSH, types.TINT32, types.TUINT64}:  ssa.OpLsh32x64,
  2717  	{ir.OLSH, types.TUINT32, types.TUINT64}: ssa.OpLsh32x64,
  2718  
  2719  	{ir.OLSH, types.TINT64, types.TUINT8}:   ssa.OpLsh64x8,
  2720  	{ir.OLSH, types.TUINT64, types.TUINT8}:  ssa.OpLsh64x8,
  2721  	{ir.OLSH, types.TINT64, types.TUINT16}:  ssa.OpLsh64x16,
  2722  	{ir.OLSH, types.TUINT64, types.TUINT16}: ssa.OpLsh64x16,
  2723  	{ir.OLSH, types.TINT64, types.TUINT32}:  ssa.OpLsh64x32,
  2724  	{ir.OLSH, types.TUINT64, types.TUINT32}: ssa.OpLsh64x32,
  2725  	{ir.OLSH, types.TINT64, types.TUINT64}:  ssa.OpLsh64x64,
  2726  	{ir.OLSH, types.TUINT64, types.TUINT64}: ssa.OpLsh64x64,
  2727  
  2728  	{ir.ORSH, types.TINT8, types.TUINT8}:   ssa.OpRsh8x8,
  2729  	{ir.ORSH, types.TUINT8, types.TUINT8}:  ssa.OpRsh8Ux8,
  2730  	{ir.ORSH, types.TINT8, types.TUINT16}:  ssa.OpRsh8x16,
  2731  	{ir.ORSH, types.TUINT8, types.TUINT16}: ssa.OpRsh8Ux16,
  2732  	{ir.ORSH, types.TINT8, types.TUINT32}:  ssa.OpRsh8x32,
  2733  	{ir.ORSH, types.TUINT8, types.TUINT32}: ssa.OpRsh8Ux32,
  2734  	{ir.ORSH, types.TINT8, types.TUINT64}:  ssa.OpRsh8x64,
  2735  	{ir.ORSH, types.TUINT8, types.TUINT64}: ssa.OpRsh8Ux64,
  2736  
  2737  	{ir.ORSH, types.TINT16, types.TUINT8}:   ssa.OpRsh16x8,
  2738  	{ir.ORSH, types.TUINT16, types.TUINT8}:  ssa.OpRsh16Ux8,
  2739  	{ir.ORSH, types.TINT16, types.TUINT16}:  ssa.OpRsh16x16,
  2740  	{ir.ORSH, types.TUINT16, types.TUINT16}: ssa.OpRsh16Ux16,
  2741  	{ir.ORSH, types.TINT16, types.TUINT32}:  ssa.OpRsh16x32,
  2742  	{ir.ORSH, types.TUINT16, types.TUINT32}: ssa.OpRsh16Ux32,
  2743  	{ir.ORSH, types.TINT16, types.TUINT64}:  ssa.OpRsh16x64,
  2744  	{ir.ORSH, types.TUINT16, types.TUINT64}: ssa.OpRsh16Ux64,
  2745  
  2746  	{ir.ORSH, types.TINT32, types.TUINT8}:   ssa.OpRsh32x8,
  2747  	{ir.ORSH, types.TUINT32, types.TUINT8}:  ssa.OpRsh32Ux8,
  2748  	{ir.ORSH, types.TINT32, types.TUINT16}:  ssa.OpRsh32x16,
  2749  	{ir.ORSH, types.TUINT32, types.TUINT16}: ssa.OpRsh32Ux16,
  2750  	{ir.ORSH, types.TINT32, types.TUINT32}:  ssa.OpRsh32x32,
  2751  	{ir.ORSH, types.TUINT32, types.TUINT32}: ssa.OpRsh32Ux32,
  2752  	{ir.ORSH, types.TINT32, types.TUINT64}:  ssa.OpRsh32x64,
  2753  	{ir.ORSH, types.TUINT32, types.TUINT64}: ssa.OpRsh32Ux64,
  2754  
  2755  	{ir.ORSH, types.TINT64, types.TUINT8}:   ssa.OpRsh64x8,
  2756  	{ir.ORSH, types.TUINT64, types.TUINT8}:  ssa.OpRsh64Ux8,
  2757  	{ir.ORSH, types.TINT64, types.TUINT16}:  ssa.OpRsh64x16,
  2758  	{ir.ORSH, types.TUINT64, types.TUINT16}: ssa.OpRsh64Ux16,
  2759  	{ir.ORSH, types.TINT64, types.TUINT32}:  ssa.OpRsh64x32,
  2760  	{ir.ORSH, types.TUINT64, types.TUINT32}: ssa.OpRsh64Ux32,
  2761  	{ir.ORSH, types.TINT64, types.TUINT64}:  ssa.OpRsh64x64,
  2762  	{ir.ORSH, types.TUINT64, types.TUINT64}: ssa.OpRsh64Ux64,
  2763  }
  2764  
  2765  func (s *state) ssaShiftOp(op ir.Op, t *types.Type, u *types.Type) ssa.Op {
  2766  	etype1 := s.concreteEtype(t)
  2767  	etype2 := s.concreteEtype(u)
  2768  	x, ok := shiftOpToSSA[opAndTwoTypes{op, etype1, etype2}]
  2769  	if !ok {
  2770  		s.Fatalf("unhandled shift op %v etype=%s/%s", op, etype1, etype2)
  2771  	}
  2772  	return x
  2773  }
  2774  
  2775  func (s *state) uintptrConstant(v uint64) *ssa.Value {
  2776  	if s.config.PtrSize == 4 {
  2777  		return s.newValue0I(ssa.OpConst32, types.Types[types.TUINTPTR], int64(v))
  2778  	}
  2779  	return s.newValue0I(ssa.OpConst64, types.Types[types.TUINTPTR], int64(v))
  2780  }
  2781  
  2782  func (s *state) conv(n ir.Node, v *ssa.Value, ft, tt *types.Type) *ssa.Value {
  2783  	if ft.IsBoolean() && tt.IsKind(types.TUINT8) {
  2784  		// Bool -> uint8 is generated internally when indexing into runtime.staticbyte.
  2785  		return s.newValue1(ssa.OpCvtBoolToUint8, tt, v)
  2786  	}
  2787  	if ft.IsInteger() && tt.IsInteger() {
  2788  		var op ssa.Op
  2789  		if tt.Size() == ft.Size() {
  2790  			op = ssa.OpCopy
  2791  		} else if tt.Size() < ft.Size() {
  2792  			// truncation
  2793  			switch 10*ft.Size() + tt.Size() {
  2794  			case 21:
  2795  				op = ssa.OpTrunc16to8
  2796  			case 41:
  2797  				op = ssa.OpTrunc32to8
  2798  			case 42:
  2799  				op = ssa.OpTrunc32to16
  2800  			case 81:
  2801  				op = ssa.OpTrunc64to8
  2802  			case 82:
  2803  				op = ssa.OpTrunc64to16
  2804  			case 84:
  2805  				op = ssa.OpTrunc64to32
  2806  			default:
  2807  				s.Fatalf("weird integer truncation %v -> %v", ft, tt)
  2808  			}
  2809  		} else if ft.IsSigned() {
  2810  			// sign extension
  2811  			switch 10*ft.Size() + tt.Size() {
  2812  			case 12:
  2813  				op = ssa.OpSignExt8to16
  2814  			case 14:
  2815  				op = ssa.OpSignExt8to32
  2816  			case 18:
  2817  				op = ssa.OpSignExt8to64
  2818  			case 24:
  2819  				op = ssa.OpSignExt16to32
  2820  			case 28:
  2821  				op = ssa.OpSignExt16to64
  2822  			case 48:
  2823  				op = ssa.OpSignExt32to64
  2824  			default:
  2825  				s.Fatalf("bad integer sign extension %v -> %v", ft, tt)
  2826  			}
  2827  		} else {
  2828  			// zero extension
  2829  			switch 10*ft.Size() + tt.Size() {
  2830  			case 12:
  2831  				op = ssa.OpZeroExt8to16
  2832  			case 14:
  2833  				op = ssa.OpZeroExt8to32
  2834  			case 18:
  2835  				op = ssa.OpZeroExt8to64
  2836  			case 24:
  2837  				op = ssa.OpZeroExt16to32
  2838  			case 28:
  2839  				op = ssa.OpZeroExt16to64
  2840  			case 48:
  2841  				op = ssa.OpZeroExt32to64
  2842  			default:
  2843  				s.Fatalf("weird integer sign extension %v -> %v", ft, tt)
  2844  			}
  2845  		}
  2846  		return s.newValue1(op, tt, v)
  2847  	}
  2848  
  2849  	if ft.IsComplex() && tt.IsComplex() {
  2850  		var op ssa.Op
  2851  		if ft.Size() == tt.Size() {
  2852  			switch ft.Size() {
  2853  			case 8:
  2854  				op = ssa.OpRound32F
  2855  			case 16:
  2856  				op = ssa.OpRound64F
  2857  			default:
  2858  				s.Fatalf("weird complex conversion %v -> %v", ft, tt)
  2859  			}
  2860  		} else if ft.Size() == 8 && tt.Size() == 16 {
  2861  			op = ssa.OpCvt32Fto64F
  2862  		} else if ft.Size() == 16 && tt.Size() == 8 {
  2863  			op = ssa.OpCvt64Fto32F
  2864  		} else {
  2865  			s.Fatalf("weird complex conversion %v -> %v", ft, tt)
  2866  		}
  2867  		ftp := types.FloatForComplex(ft)
  2868  		ttp := types.FloatForComplex(tt)
  2869  		return s.newValue2(ssa.OpComplexMake, tt,
  2870  			s.newValueOrSfCall1(op, ttp, s.newValue1(ssa.OpComplexReal, ftp, v)),
  2871  			s.newValueOrSfCall1(op, ttp, s.newValue1(ssa.OpComplexImag, ftp, v)))
  2872  	}
  2873  
  2874  	if tt.IsComplex() { // and ft is not complex
  2875  		// Needed for generics support - can't happen in normal Go code.
  2876  		et := types.FloatForComplex(tt)
  2877  		v = s.conv(n, v, ft, et)
  2878  		return s.newValue2(ssa.OpComplexMake, tt, v, s.zeroVal(et))
  2879  	}
  2880  
  2881  	if ft.IsFloat() || tt.IsFloat() {
  2882  		cft, ctt := s.concreteEtype(ft), s.concreteEtype(tt)
  2883  		conv, ok := fpConvOpToSSA[twoTypes{cft, ctt}]
  2884  		// there's a change to a conversion-op table, this restores the old behavior if ConvertHash is false.
  2885  		// use salted hash to distinguish unsigned convert at a Pos from signed convert at a Pos
  2886  		if ctt == types.TUINT32 && ft.IsFloat() && !base.ConvertHash.MatchPosWithInfo(n.Pos(), "U", nil) {
  2887  			// revert to old behavior
  2888  			conv.op1 = ssa.OpCvt64Fto64
  2889  			if cft == types.TFLOAT32 {
  2890  				conv.op1 = ssa.OpCvt32Fto64
  2891  			}
  2892  			conv.op2 = ssa.OpTrunc64to32
  2893  
  2894  		}
  2895  		if s.config.RegSize == 4 && Arch.LinkArch.Family != sys.MIPS && !s.softFloat {
  2896  			if conv1, ok1 := fpConvOpToSSA32[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
  2897  				conv = conv1
  2898  			}
  2899  		}
  2900  		if Arch.LinkArch.Family == sys.ARM64 || Arch.LinkArch.Family == sys.Wasm || Arch.LinkArch.Family == sys.S390X || s.softFloat {
  2901  			if conv1, ok1 := uint64fpConvOpToSSA[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
  2902  				conv = conv1
  2903  			}
  2904  		}
  2905  
  2906  		if Arch.LinkArch.Family == sys.MIPS && !s.softFloat {
  2907  			if ft.Size() == 4 && ft.IsInteger() && !ft.IsSigned() {
  2908  				// tt is float32 or float64, and ft is also unsigned
  2909  				if tt.Size() == 4 {
  2910  					return s.uint32Tofloat32(n, v, ft, tt)
  2911  				}
  2912  				if tt.Size() == 8 {
  2913  					return s.uint32Tofloat64(n, v, ft, tt)
  2914  				}
  2915  			} else if tt.Size() == 4 && tt.IsInteger() && !tt.IsSigned() {
  2916  				// ft is float32 or float64, and tt is unsigned integer
  2917  				if ft.Size() == 4 {
  2918  					return s.float32ToUint32(n, v, ft, tt)
  2919  				}
  2920  				if ft.Size() == 8 {
  2921  					return s.float64ToUint32(n, v, ft, tt)
  2922  				}
  2923  			}
  2924  		}
  2925  
  2926  		if !ok {
  2927  			s.Fatalf("weird float conversion %v -> %v", ft, tt)
  2928  		}
  2929  		op1, op2, it := conv.op1, conv.op2, conv.intermediateType
  2930  
  2931  		if op1 != ssa.OpInvalid && op2 != ssa.OpInvalid {
  2932  			// normal case, not tripping over unsigned 64
  2933  			if op1 == ssa.OpCopy {
  2934  				if op2 == ssa.OpCopy {
  2935  					return v
  2936  				}
  2937  				return s.newValueOrSfCall1(op2, tt, v)
  2938  			}
  2939  			if op2 == ssa.OpCopy {
  2940  				return s.newValueOrSfCall1(op1, tt, v)
  2941  			}
  2942  			return s.newValueOrSfCall1(op2, tt, s.newValueOrSfCall1(op1, types.Types[it], v))
  2943  		}
  2944  		// Tricky 64-bit unsigned cases.
  2945  		if ft.IsInteger() {
  2946  			// tt is float32 or float64, and ft is also unsigned
  2947  			if tt.Size() == 4 {
  2948  				return s.uint64Tofloat32(n, v, ft, tt)
  2949  			}
  2950  			if tt.Size() == 8 {
  2951  				return s.uint64Tofloat64(n, v, ft, tt)
  2952  			}
  2953  			s.Fatalf("weird unsigned integer to float conversion %v -> %v", ft, tt)
  2954  		}
  2955  		// ft is float32 or float64, and tt is unsigned integer
  2956  		if ft.Size() == 4 {
  2957  			switch tt.Size() {
  2958  			case 8:
  2959  				return s.float32ToUint64(n, v, ft, tt)
  2960  			case 4, 2, 1:
  2961  				// TODO should 2 and 1 saturate or truncate?
  2962  				return s.float32ToUint32(n, v, ft, tt)
  2963  			}
  2964  		}
  2965  		if ft.Size() == 8 {
  2966  			switch tt.Size() {
  2967  			case 8:
  2968  				return s.float64ToUint64(n, v, ft, tt)
  2969  			case 4, 2, 1:
  2970  				// TODO should 2 and 1 saturate or truncate?
  2971  				return s.float64ToUint32(n, v, ft, tt)
  2972  			}
  2973  
  2974  		}
  2975  		s.Fatalf("weird float to unsigned integer conversion %v -> %v", ft, tt)
  2976  		return nil
  2977  	}
  2978  
  2979  	s.Fatalf("unhandled OCONV %s -> %s", ft.Kind(), tt.Kind())
  2980  	return nil
  2981  }
  2982  
  2983  // expr converts the expression n to ssa, adds it to s and returns the ssa result.
  2984  func (s *state) expr(n ir.Node) *ssa.Value {
  2985  	return s.exprCheckPtr(n, true)
  2986  }
  2987  
  2988  func (s *state) exprCheckPtr(n ir.Node, checkPtrOK bool) *ssa.Value {
  2989  	if ir.HasUniquePos(n) {
  2990  		// ONAMEs and named OLITERALs have the line number
  2991  		// of the decl, not the use. See issue 14742.
  2992  		s.pushLine(n.Pos())
  2993  		defer s.popLine()
  2994  	}
  2995  
  2996  	s.stmtList(n.Init())
  2997  	switch n.Op() {
  2998  	case ir.OBYTES2STRTMP:
  2999  		n := n.(*ir.ConvExpr)
  3000  		slice := s.expr(n.X)
  3001  		ptr := s.newValue1(ssa.OpSlicePtr, s.f.Config.Types.BytePtr, slice)
  3002  		len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], slice)
  3003  		return s.newValue2(ssa.OpStringMake, n.Type(), ptr, len)
  3004  	case ir.OSTR2BYTESTMP:
  3005  		n := n.(*ir.ConvExpr)
  3006  		str := s.expr(n.X)
  3007  		ptr := s.newValue1(ssa.OpStringPtr, s.f.Config.Types.BytePtr, str)
  3008  		if !n.NonNil() {
  3009  			// We need to ensure []byte("") evaluates to []byte{}, and not []byte(nil).
  3010  			//
  3011  			// TODO(mdempsky): Investigate using "len != 0" instead of "ptr != nil".
  3012  			cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], ptr, s.constNil(ptr.Type))
  3013  			zerobase := s.newValue1A(ssa.OpAddr, ptr.Type, ir.Syms.Zerobase, s.sb)
  3014  			ptr = s.ternary(cond, ptr, zerobase)
  3015  		}
  3016  		len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], str)
  3017  		return s.newValue3(ssa.OpSliceMake, n.Type(), ptr, len, len)
  3018  	case ir.OCFUNC:
  3019  		n := n.(*ir.UnaryExpr)
  3020  		aux := n.X.(*ir.Name).Linksym()
  3021  		// OCFUNC is used to build function values, which must
  3022  		// always reference ABIInternal entry points.
  3023  		if aux.ABI() != obj.ABIInternal {
  3024  			s.Fatalf("expected ABIInternal: %v", aux.ABI())
  3025  		}
  3026  		return s.entryNewValue1A(ssa.OpAddr, n.Type(), aux, s.sb)
  3027  	case ir.ONAME:
  3028  		n := n.(*ir.Name)
  3029  		if n.Class == ir.PFUNC {
  3030  			// "value" of a function is the address of the function's closure
  3031  			sym := staticdata.FuncLinksym(n)
  3032  			return s.entryNewValue1A(ssa.OpAddr, types.NewPtr(n.Type()), sym, s.sb)
  3033  		}
  3034  		if s.canSSA(n) {
  3035  			return s.variable(n, n.Type())
  3036  		}
  3037  		return s.load(n.Type(), s.addr(n))
  3038  	case ir.OLINKSYMOFFSET:
  3039  		n := n.(*ir.LinksymOffsetExpr)
  3040  		return s.load(n.Type(), s.addr(n))
  3041  	case ir.ONIL:
  3042  		n := n.(*ir.NilExpr)
  3043  		t := n.Type()
  3044  		switch {
  3045  		case t.IsSlice():
  3046  			return s.constSlice(t)
  3047  		case t.IsInterface():
  3048  			return s.constInterface(t)
  3049  		default:
  3050  			return s.constNil(t)
  3051  		}
  3052  	case ir.OLITERAL:
  3053  		switch u := n.Val(); u.Kind() {
  3054  		case constant.Int:
  3055  			i := ir.IntVal(n.Type(), u)
  3056  			switch n.Type().Size() {
  3057  			case 1:
  3058  				return s.constInt8(n.Type(), int8(i))
  3059  			case 2:
  3060  				return s.constInt16(n.Type(), int16(i))
  3061  			case 4:
  3062  				return s.constInt32(n.Type(), int32(i))
  3063  			case 8:
  3064  				return s.constInt64(n.Type(), i)
  3065  			default:
  3066  				s.Fatalf("bad integer size %d", n.Type().Size())
  3067  				return nil
  3068  			}
  3069  		case constant.String:
  3070  			i := constant.StringVal(u)
  3071  			if i == "" {
  3072  				return s.constEmptyString(n.Type())
  3073  			}
  3074  			return s.entryNewValue0A(ssa.OpConstString, n.Type(), ssa.StringToAux(i))
  3075  		case constant.Bool:
  3076  			return s.constBool(constant.BoolVal(u))
  3077  		case constant.Float:
  3078  			f, _ := constant.Float64Val(u)
  3079  			switch n.Type().Size() {
  3080  			case 4:
  3081  				return s.constFloat32(n.Type(), f)
  3082  			case 8:
  3083  				return s.constFloat64(n.Type(), f)
  3084  			default:
  3085  				s.Fatalf("bad float size %d", n.Type().Size())
  3086  				return nil
  3087  			}
  3088  		case constant.Complex:
  3089  			re, _ := constant.Float64Val(constant.Real(u))
  3090  			im, _ := constant.Float64Val(constant.Imag(u))
  3091  			switch n.Type().Size() {
  3092  			case 8:
  3093  				pt := types.Types[types.TFLOAT32]
  3094  				return s.newValue2(ssa.OpComplexMake, n.Type(),
  3095  					s.constFloat32(pt, re),
  3096  					s.constFloat32(pt, im))
  3097  			case 16:
  3098  				pt := types.Types[types.TFLOAT64]
  3099  				return s.newValue2(ssa.OpComplexMake, n.Type(),
  3100  					s.constFloat64(pt, re),
  3101  					s.constFloat64(pt, im))
  3102  			default:
  3103  				s.Fatalf("bad complex size %d", n.Type().Size())
  3104  				return nil
  3105  			}
  3106  		default:
  3107  			s.Fatalf("unhandled OLITERAL %v", u.Kind())
  3108  			return nil
  3109  		}
  3110  	case ir.OCONVNOP:
  3111  		n := n.(*ir.ConvExpr)
  3112  		to := n.Type()
  3113  		from := n.X.Type()
  3114  
  3115  		// Assume everything will work out, so set up our return value.
  3116  		// Anything interesting that happens from here is a fatal.
  3117  		x := s.expr(n.X)
  3118  		if to == from {
  3119  			return x
  3120  		}
  3121  
  3122  		// Special case for not confusing GC and liveness.
  3123  		// We don't want pointers accidentally classified
  3124  		// as not-pointers or vice-versa because of copy
  3125  		// elision.
  3126  		if to.IsPtrShaped() != from.IsPtrShaped() {
  3127  			return s.newValue2(ssa.OpConvert, to, x, s.mem())
  3128  		}
  3129  
  3130  		v := s.newValue1(ssa.OpCopy, to, x) // ensure that v has the right type
  3131  
  3132  		// CONVNOP closure
  3133  		if to.Kind() == types.TFUNC && from.IsPtrShaped() {
  3134  			return v
  3135  		}
  3136  
  3137  		// named <--> unnamed type or typed <--> untyped const
  3138  		if from.Kind() == to.Kind() {
  3139  			return v
  3140  		}
  3141  
  3142  		// unsafe.Pointer <--> *T
  3143  		if to.IsUnsafePtr() && from.IsPtrShaped() || from.IsUnsafePtr() && to.IsPtrShaped() {
  3144  			if s.checkPtrEnabled && checkPtrOK && to.IsPtr() && from.IsUnsafePtr() {
  3145  				s.checkPtrAlignment(n, v, nil)
  3146  			}
  3147  			return v
  3148  		}
  3149  
  3150  		// map <--> *internal/runtime/maps.Map
  3151  		mt := types.NewPtr(reflectdata.MapType())
  3152  		if to.Kind() == types.TMAP && from == mt {
  3153  			return v
  3154  		}
  3155  
  3156  		types.CalcSize(from)
  3157  		types.CalcSize(to)
  3158  		if from.Size() != to.Size() {
  3159  			s.Fatalf("CONVNOP width mismatch %v (%d) -> %v (%d)\n", from, from.Size(), to, to.Size())
  3160  			return nil
  3161  		}
  3162  		if etypesign(from.Kind()) != etypesign(to.Kind()) {
  3163  			s.Fatalf("CONVNOP sign mismatch %v (%s) -> %v (%s)\n", from, from.Kind(), to, to.Kind())
  3164  			return nil
  3165  		}
  3166  
  3167  		if base.Flag.Cfg.Instrumenting {
  3168  			// These appear to be fine, but they fail the
  3169  			// integer constraint below, so okay them here.
  3170  			// Sample non-integer conversion: map[string]string -> *uint8
  3171  			return v
  3172  		}
  3173  
  3174  		if etypesign(from.Kind()) == 0 {
  3175  			s.Fatalf("CONVNOP unrecognized non-integer %v -> %v\n", from, to)
  3176  			return nil
  3177  		}
  3178  
  3179  		// integer, same width, same sign
  3180  		return v
  3181  
  3182  	case ir.OCONV:
  3183  		n := n.(*ir.ConvExpr)
  3184  		x := s.expr(n.X)
  3185  		return s.conv(n, x, n.X.Type(), n.Type())
  3186  
  3187  	case ir.ODOTTYPE:
  3188  		n := n.(*ir.TypeAssertExpr)
  3189  		res, _ := s.dottype(n, false)
  3190  		return res
  3191  
  3192  	case ir.ODYNAMICDOTTYPE:
  3193  		n := n.(*ir.DynamicTypeAssertExpr)
  3194  		res, _ := s.dynamicDottype(n, false)
  3195  		return res
  3196  
  3197  	// binary ops
  3198  	case ir.OLT, ir.OEQ, ir.ONE, ir.OLE, ir.OGE, ir.OGT:
  3199  		n := n.(*ir.BinaryExpr)
  3200  		a := s.expr(n.X)
  3201  		b := s.expr(n.Y)
  3202  		if n.X.Type().IsComplex() {
  3203  			pt := types.FloatForComplex(n.X.Type())
  3204  			op := s.ssaOp(ir.OEQ, pt)
  3205  			r := s.newValueOrSfCall2(op, types.Types[types.TBOOL], s.newValue1(ssa.OpComplexReal, pt, a), s.newValue1(ssa.OpComplexReal, pt, b))
  3206  			i := s.newValueOrSfCall2(op, types.Types[types.TBOOL], s.newValue1(ssa.OpComplexImag, pt, a), s.newValue1(ssa.OpComplexImag, pt, b))
  3207  			c := s.newValue2(ssa.OpAndB, types.Types[types.TBOOL], r, i)
  3208  			switch n.Op() {
  3209  			case ir.OEQ:
  3210  				return c
  3211  			case ir.ONE:
  3212  				return s.newValue1(ssa.OpNot, types.Types[types.TBOOL], c)
  3213  			default:
  3214  				s.Fatalf("ordered complex compare %v", n.Op())
  3215  			}
  3216  		}
  3217  
  3218  		// Convert OGE and OGT into OLE and OLT.
  3219  		op := n.Op()
  3220  		switch op {
  3221  		case ir.OGE:
  3222  			op, a, b = ir.OLE, b, a
  3223  		case ir.OGT:
  3224  			op, a, b = ir.OLT, b, a
  3225  		}
  3226  		if n.X.Type().IsFloat() {
  3227  			// float comparison
  3228  			return s.newValueOrSfCall2(s.ssaOp(op, n.X.Type()), types.Types[types.TBOOL], a, b)
  3229  		}
  3230  		// integer comparison
  3231  		return s.newValue2(s.ssaOp(op, n.X.Type()), types.Types[types.TBOOL], a, b)
  3232  	case ir.OMUL:
  3233  		n := n.(*ir.BinaryExpr)
  3234  		a := s.expr(n.X)
  3235  		b := s.expr(n.Y)
  3236  		if n.Type().IsComplex() {
  3237  			mulop := ssa.OpMul64F
  3238  			addop := ssa.OpAdd64F
  3239  			subop := ssa.OpSub64F
  3240  			pt := types.FloatForComplex(n.Type()) // Could be Float32 or Float64
  3241  			wt := types.Types[types.TFLOAT64]     // Compute in Float64 to minimize cancellation error
  3242  
  3243  			areal := s.newValue1(ssa.OpComplexReal, pt, a)
  3244  			breal := s.newValue1(ssa.OpComplexReal, pt, b)
  3245  			aimag := s.newValue1(ssa.OpComplexImag, pt, a)
  3246  			bimag := s.newValue1(ssa.OpComplexImag, pt, b)
  3247  
  3248  			if pt != wt { // Widen for calculation
  3249  				areal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, areal)
  3250  				breal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, breal)
  3251  				aimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, aimag)
  3252  				bimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, bimag)
  3253  			}
  3254  
  3255  			xreal := s.newValueOrSfCall2(subop, wt, s.newValueOrSfCall2(mulop, wt, areal, breal), s.newValueOrSfCall2(mulop, wt, aimag, bimag))
  3256  			ximag := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, areal, bimag), s.newValueOrSfCall2(mulop, wt, aimag, breal))
  3257  
  3258  			if pt != wt { // Narrow to store back
  3259  				xreal = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, xreal)
  3260  				ximag = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, ximag)
  3261  			}
  3262  
  3263  			return s.newValue2(ssa.OpComplexMake, n.Type(), xreal, ximag)
  3264  		}
  3265  
  3266  		if n.Type().IsFloat() {
  3267  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3268  		}
  3269  
  3270  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3271  
  3272  	case ir.ODIV:
  3273  		n := n.(*ir.BinaryExpr)
  3274  		a := s.expr(n.X)
  3275  		b := s.expr(n.Y)
  3276  		if n.Type().IsComplex() {
  3277  			// TODO this is not executed because the front-end substitutes a runtime call.
  3278  			// That probably ought to change; with modest optimization the widen/narrow
  3279  			// conversions could all be elided in larger expression trees.
  3280  			mulop := ssa.OpMul64F
  3281  			addop := ssa.OpAdd64F
  3282  			subop := ssa.OpSub64F
  3283  			divop := ssa.OpDiv64F
  3284  			pt := types.FloatForComplex(n.Type()) // Could be Float32 or Float64
  3285  			wt := types.Types[types.TFLOAT64]     // Compute in Float64 to minimize cancellation error
  3286  
  3287  			areal := s.newValue1(ssa.OpComplexReal, pt, a)
  3288  			breal := s.newValue1(ssa.OpComplexReal, pt, b)
  3289  			aimag := s.newValue1(ssa.OpComplexImag, pt, a)
  3290  			bimag := s.newValue1(ssa.OpComplexImag, pt, b)
  3291  
  3292  			if pt != wt { // Widen for calculation
  3293  				areal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, areal)
  3294  				breal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, breal)
  3295  				aimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, aimag)
  3296  				bimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, bimag)
  3297  			}
  3298  
  3299  			denom := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, breal, breal), s.newValueOrSfCall2(mulop, wt, bimag, bimag))
  3300  			xreal := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, areal, breal), s.newValueOrSfCall2(mulop, wt, aimag, bimag))
  3301  			ximag := s.newValueOrSfCall2(subop, wt, s.newValueOrSfCall2(mulop, wt, aimag, breal), s.newValueOrSfCall2(mulop, wt, areal, bimag))
  3302  
  3303  			// TODO not sure if this is best done in wide precision or narrow
  3304  			// Double-rounding might be an issue.
  3305  			// Note that the pre-SSA implementation does the entire calculation
  3306  			// in wide format, so wide is compatible.
  3307  			xreal = s.newValueOrSfCall2(divop, wt, xreal, denom)
  3308  			ximag = s.newValueOrSfCall2(divop, wt, ximag, denom)
  3309  
  3310  			if pt != wt { // Narrow to store back
  3311  				xreal = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, xreal)
  3312  				ximag = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, ximag)
  3313  			}
  3314  			return s.newValue2(ssa.OpComplexMake, n.Type(), xreal, ximag)
  3315  		}
  3316  		if n.Type().IsFloat() {
  3317  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3318  		}
  3319  		return s.intDivide(n, a, b)
  3320  	case ir.OMOD:
  3321  		n := n.(*ir.BinaryExpr)
  3322  		a := s.expr(n.X)
  3323  		b := s.expr(n.Y)
  3324  		return s.intDivide(n, a, b)
  3325  	case ir.OADD, ir.OSUB:
  3326  		n := n.(*ir.BinaryExpr)
  3327  		a := s.expr(n.X)
  3328  		b := s.expr(n.Y)
  3329  		if n.Type().IsComplex() {
  3330  			pt := types.FloatForComplex(n.Type())
  3331  			op := s.ssaOp(n.Op(), pt)
  3332  			return s.newValue2(ssa.OpComplexMake, n.Type(),
  3333  				s.newValueOrSfCall2(op, pt, s.newValue1(ssa.OpComplexReal, pt, a), s.newValue1(ssa.OpComplexReal, pt, b)),
  3334  				s.newValueOrSfCall2(op, pt, s.newValue1(ssa.OpComplexImag, pt, a), s.newValue1(ssa.OpComplexImag, pt, b)))
  3335  		}
  3336  		if n.Type().IsFloat() {
  3337  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3338  		}
  3339  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3340  	case ir.OAND, ir.OOR, ir.OXOR:
  3341  		n := n.(*ir.BinaryExpr)
  3342  		a := s.expr(n.X)
  3343  		b := s.expr(n.Y)
  3344  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3345  	case ir.OANDNOT:
  3346  		n := n.(*ir.BinaryExpr)
  3347  		a := s.expr(n.X)
  3348  		b := s.expr(n.Y)
  3349  		b = s.newValue1(s.ssaOp(ir.OBITNOT, b.Type), b.Type, b)
  3350  		return s.newValue2(s.ssaOp(ir.OAND, n.Type()), a.Type, a, b)
  3351  	case ir.OLSH, ir.ORSH:
  3352  		n := n.(*ir.BinaryExpr)
  3353  		a := s.expr(n.X)
  3354  		b := s.expr(n.Y)
  3355  		bt := b.Type
  3356  		if bt.IsSigned() {
  3357  			cmp := s.newValue2(s.ssaOp(ir.OLE, bt), types.Types[types.TBOOL], s.zeroVal(bt), b)
  3358  			s.check(cmp, ir.Syms.Panicshift)
  3359  			bt = bt.ToUnsigned()
  3360  		}
  3361  		return s.newValue2(s.ssaShiftOp(n.Op(), n.Type(), bt), a.Type, a, b)
  3362  	case ir.OANDAND, ir.OOROR:
  3363  		// To implement OANDAND (and OOROR), we introduce a
  3364  		// new temporary variable to hold the result. The
  3365  		// variable is associated with the OANDAND node in the
  3366  		// s.vars table (normally variables are only
  3367  		// associated with ONAME nodes). We convert
  3368  		//     A && B
  3369  		// to
  3370  		//     var = A
  3371  		//     if var {
  3372  		//         var = B
  3373  		//     }
  3374  		// Using var in the subsequent block introduces the
  3375  		// necessary phi variable.
  3376  		n := n.(*ir.LogicalExpr)
  3377  		el := s.expr(n.X)
  3378  		s.vars[n] = el
  3379  
  3380  		b := s.endBlock()
  3381  		b.Kind = ssa.BlockIf
  3382  		b.SetControl(el)
  3383  		// In theory, we should set b.Likely here based on context.
  3384  		// However, gc only gives us likeliness hints
  3385  		// in a single place, for plain OIF statements,
  3386  		// and passing around context is finicky, so don't bother for now.
  3387  
  3388  		bRight := s.f.NewBlock(ssa.BlockPlain)
  3389  		bResult := s.f.NewBlock(ssa.BlockPlain)
  3390  		if n.Op() == ir.OANDAND {
  3391  			b.AddEdgeTo(bRight)
  3392  			b.AddEdgeTo(bResult)
  3393  		} else if n.Op() == ir.OOROR {
  3394  			b.AddEdgeTo(bResult)
  3395  			b.AddEdgeTo(bRight)
  3396  		}
  3397  
  3398  		s.startBlock(bRight)
  3399  		er := s.expr(n.Y)
  3400  		s.vars[n] = er
  3401  
  3402  		b = s.endBlock()
  3403  		b.AddEdgeTo(bResult)
  3404  
  3405  		s.startBlock(bResult)
  3406  		return s.variable(n, types.Types[types.TBOOL])
  3407  	case ir.OCOMPLEX:
  3408  		n := n.(*ir.BinaryExpr)
  3409  		r := s.expr(n.X)
  3410  		i := s.expr(n.Y)
  3411  		return s.newValue2(ssa.OpComplexMake, n.Type(), r, i)
  3412  
  3413  	// unary ops
  3414  	case ir.ONEG:
  3415  		n := n.(*ir.UnaryExpr)
  3416  		a := s.expr(n.X)
  3417  		if n.Type().IsComplex() {
  3418  			tp := types.FloatForComplex(n.Type())
  3419  			negop := s.ssaOp(n.Op(), tp)
  3420  			return s.newValue2(ssa.OpComplexMake, n.Type(),
  3421  				s.newValue1(negop, tp, s.newValue1(ssa.OpComplexReal, tp, a)),
  3422  				s.newValue1(negop, tp, s.newValue1(ssa.OpComplexImag, tp, a)))
  3423  		}
  3424  		return s.newValue1(s.ssaOp(n.Op(), n.Type()), a.Type, a)
  3425  	case ir.ONOT, ir.OBITNOT:
  3426  		n := n.(*ir.UnaryExpr)
  3427  		a := s.expr(n.X)
  3428  		return s.newValue1(s.ssaOp(n.Op(), n.Type()), a.Type, a)
  3429  	case ir.OIMAG, ir.OREAL:
  3430  		n := n.(*ir.UnaryExpr)
  3431  		a := s.expr(n.X)
  3432  		return s.newValue1(s.ssaOp(n.Op(), n.X.Type()), n.Type(), a)
  3433  	case ir.OPLUS:
  3434  		n := n.(*ir.UnaryExpr)
  3435  		return s.expr(n.X)
  3436  
  3437  	case ir.OADDR:
  3438  		n := n.(*ir.AddrExpr)
  3439  		return s.addr(n.X)
  3440  
  3441  	case ir.ORESULT:
  3442  		n := n.(*ir.ResultExpr)
  3443  		if s.prevCall == nil || s.prevCall.Op != ssa.OpStaticLECall && s.prevCall.Op != ssa.OpInterLECall && s.prevCall.Op != ssa.OpClosureLECall {
  3444  			panic("Expected to see a previous call")
  3445  		}
  3446  		which := n.Index
  3447  		if which == -1 {
  3448  			panic(fmt.Errorf("ORESULT %v does not match call %s", n, s.prevCall))
  3449  		}
  3450  		return s.resultOfCall(s.prevCall, which, n.Type())
  3451  
  3452  	case ir.ODEREF:
  3453  		n := n.(*ir.StarExpr)
  3454  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  3455  		return s.load(n.Type(), p)
  3456  
  3457  	case ir.ODOT:
  3458  		n := n.(*ir.SelectorExpr)
  3459  		if n.X.Op() == ir.OSTRUCTLIT {
  3460  			// All literals with nonzero fields have already been
  3461  			// rewritten during walk. Any that remain are just T{}
  3462  			// or equivalents. Use the zero value.
  3463  			if !ir.IsZero(n.X) {
  3464  				s.Fatalf("literal with nonzero value in SSA: %v", n.X)
  3465  			}
  3466  			return s.zeroVal(n.Type())
  3467  		}
  3468  		// If n is addressable and can't be represented in
  3469  		// SSA, then load just the selected field. This
  3470  		// prevents false memory dependencies in race/msan/asan
  3471  		// instrumentation.
  3472  		if ir.IsAddressable(n) && !s.canSSA(n) {
  3473  			p := s.addr(n)
  3474  			return s.load(n.Type(), p)
  3475  		}
  3476  		v := s.expr(n.X)
  3477  		return s.newValue1I(ssa.OpStructSelect, n.Type(), int64(fieldIdx(n)), v)
  3478  
  3479  	case ir.ODOTPTR:
  3480  		n := n.(*ir.SelectorExpr)
  3481  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  3482  		p = s.newValue1I(ssa.OpOffPtr, types.NewPtr(n.Type()), n.Offset(), p)
  3483  		return s.load(n.Type(), p)
  3484  
  3485  	case ir.OINDEX:
  3486  		n := n.(*ir.IndexExpr)
  3487  		switch {
  3488  		case n.X.Type().IsString():
  3489  			if n.Bounded() && ir.IsConst(n.X, constant.String) && ir.IsConst(n.Index, constant.Int) {
  3490  				// Replace "abc"[1] with 'b'.
  3491  				// Delayed until now because "abc"[1] is not an ideal constant.
  3492  				// See test/fixedbugs/issue11370.go.
  3493  				return s.newValue0I(ssa.OpConst8, types.Types[types.TUINT8], int64(int8(ir.StringVal(n.X)[ir.Int64Val(n.Index)])))
  3494  			}
  3495  			a := s.expr(n.X)
  3496  			i := s.expr(n.Index)
  3497  			len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], a)
  3498  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  3499  			ptrtyp := s.f.Config.Types.BytePtr
  3500  			ptr := s.newValue1(ssa.OpStringPtr, ptrtyp, a)
  3501  			if ir.IsConst(n.Index, constant.Int) {
  3502  				ptr = s.newValue1I(ssa.OpOffPtr, ptrtyp, ir.Int64Val(n.Index), ptr)
  3503  			} else {
  3504  				ptr = s.newValue2(ssa.OpAddPtr, ptrtyp, ptr, i)
  3505  			}
  3506  			return s.load(types.Types[types.TUINT8], ptr)
  3507  		case n.X.Type().IsSlice():
  3508  			p := s.addr(n)
  3509  			return s.load(n.X.Type().Elem(), p)
  3510  		case n.X.Type().IsArray():
  3511  			if ssa.CanSSA(n.X.Type()) {
  3512  				// SSA can handle arrays of length at most 1.
  3513  				bound := n.X.Type().NumElem()
  3514  				a := s.expr(n.X)
  3515  				i := s.expr(n.Index)
  3516  				if bound == 0 {
  3517  					// Bounds check will never succeed.  Might as well
  3518  					// use constants for the bounds check.
  3519  					z := s.constInt(types.Types[types.TINT], 0)
  3520  					s.boundsCheck(z, z, ssa.BoundsIndex, false)
  3521  					// The return value won't be live, return junk.
  3522  					// But not quite junk, in case bounds checks are turned off. See issue 48092.
  3523  					return s.zeroVal(n.Type())
  3524  				}
  3525  				len := s.constInt(types.Types[types.TINT], bound)
  3526  				s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded()) // checks i == 0
  3527  				return s.newValue1I(ssa.OpArraySelect, n.Type(), 0, a)
  3528  			}
  3529  			p := s.addr(n)
  3530  			return s.load(n.X.Type().Elem(), p)
  3531  		default:
  3532  			s.Fatalf("bad type for index %v", n.X.Type())
  3533  			return nil
  3534  		}
  3535  
  3536  	case ir.OLEN, ir.OCAP:
  3537  		n := n.(*ir.UnaryExpr)
  3538  		// Note: all constant cases are handled by the frontend. If len or cap
  3539  		// makes it here, we want the side effects of the argument. See issue 72844.
  3540  		a := s.expr(n.X)
  3541  		t := n.X.Type()
  3542  		switch {
  3543  		case t.IsSlice():
  3544  			op := ssa.OpSliceLen
  3545  			if n.Op() == ir.OCAP {
  3546  				op = ssa.OpSliceCap
  3547  			}
  3548  			return s.newValue1(op, types.Types[types.TINT], a)
  3549  		case t.IsString(): // string; not reachable for OCAP
  3550  			return s.newValue1(ssa.OpStringLen, types.Types[types.TINT], a)
  3551  		case t.IsMap(), t.IsChan():
  3552  			return s.referenceTypeBuiltin(n, a)
  3553  		case t.IsArray():
  3554  			return s.constInt(types.Types[types.TINT], t.NumElem())
  3555  		case t.IsPtr() && t.Elem().IsArray():
  3556  			return s.constInt(types.Types[types.TINT], t.Elem().NumElem())
  3557  		default:
  3558  			s.Fatalf("bad type in len/cap: %v", t)
  3559  			return nil
  3560  		}
  3561  
  3562  	case ir.OSPTR:
  3563  		n := n.(*ir.UnaryExpr)
  3564  		a := s.expr(n.X)
  3565  		if n.X.Type().IsSlice() {
  3566  			if n.Bounded() {
  3567  				return s.newValue1(ssa.OpSlicePtr, n.Type(), a)
  3568  			}
  3569  			return s.newValue1(ssa.OpSlicePtrUnchecked, n.Type(), a)
  3570  		} else {
  3571  			return s.newValue1(ssa.OpStringPtr, n.Type(), a)
  3572  		}
  3573  
  3574  	case ir.OITAB:
  3575  		n := n.(*ir.UnaryExpr)
  3576  		a := s.expr(n.X)
  3577  		return s.newValue1(ssa.OpITab, n.Type(), a)
  3578  
  3579  	case ir.OIDATA:
  3580  		n := n.(*ir.UnaryExpr)
  3581  		a := s.expr(n.X)
  3582  		return s.newValue1(ssa.OpIData, n.Type(), a)
  3583  
  3584  	case ir.OMAKEFACE:
  3585  		n := n.(*ir.BinaryExpr)
  3586  		tab := s.expr(n.X)
  3587  		data := s.expr(n.Y)
  3588  		return s.newValue2(ssa.OpIMake, n.Type(), tab, data)
  3589  
  3590  	case ir.OSLICEHEADER:
  3591  		n := n.(*ir.SliceHeaderExpr)
  3592  		p := s.expr(n.Ptr)
  3593  		l := s.expr(n.Len)
  3594  		c := s.expr(n.Cap)
  3595  		return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)
  3596  
  3597  	case ir.OSTRINGHEADER:
  3598  		n := n.(*ir.StringHeaderExpr)
  3599  		p := s.expr(n.Ptr)
  3600  		l := s.expr(n.Len)
  3601  		return s.newValue2(ssa.OpStringMake, n.Type(), p, l)
  3602  
  3603  	case ir.OSLICE, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR:
  3604  		n := n.(*ir.SliceExpr)
  3605  		check := s.checkPtrEnabled && n.Op() == ir.OSLICE3ARR && n.X.Op() == ir.OCONVNOP && n.X.(*ir.ConvExpr).X.Type().IsUnsafePtr()
  3606  		v := s.exprCheckPtr(n.X, !check)
  3607  		var i, j, k *ssa.Value
  3608  		if n.Low != nil {
  3609  			i = s.expr(n.Low)
  3610  		}
  3611  		if n.High != nil {
  3612  			j = s.expr(n.High)
  3613  		}
  3614  		if n.Max != nil {
  3615  			k = s.expr(n.Max)
  3616  		}
  3617  		p, l, c := s.slice(v, i, j, k, n.Bounded())
  3618  		if check {
  3619  			// Emit checkptr instrumentation after bound check to prevent false positive, see #46938.
  3620  			s.checkPtrAlignment(n.X.(*ir.ConvExpr), v, s.conv(n.Max, k, k.Type, types.Types[types.TUINTPTR]))
  3621  		}
  3622  		return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)
  3623  
  3624  	case ir.OSLICESTR:
  3625  		n := n.(*ir.SliceExpr)
  3626  		v := s.expr(n.X)
  3627  		var i, j *ssa.Value
  3628  		if n.Low != nil {
  3629  			i = s.expr(n.Low)
  3630  		}
  3631  		if n.High != nil {
  3632  			j = s.expr(n.High)
  3633  		}
  3634  		p, l, _ := s.slice(v, i, j, nil, n.Bounded())
  3635  		return s.newValue2(ssa.OpStringMake, n.Type(), p, l)
  3636  
  3637  	case ir.OSLICE2ARRPTR:
  3638  		// if arrlen > slice.len {
  3639  		//   panic(...)
  3640  		// }
  3641  		// slice.ptr
  3642  		n := n.(*ir.ConvExpr)
  3643  		v := s.expr(n.X)
  3644  		nelem := n.Type().Elem().NumElem()
  3645  		arrlen := s.constInt(types.Types[types.TINT], nelem)
  3646  		cap := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], v)
  3647  		s.boundsCheck(arrlen, cap, ssa.BoundsConvert, false)
  3648  		op := ssa.OpSlicePtr
  3649  		if nelem == 0 {
  3650  			op = ssa.OpSlicePtrUnchecked
  3651  		}
  3652  		return s.newValue1(op, n.Type(), v)
  3653  
  3654  	case ir.OCALLFUNC:
  3655  		n := n.(*ir.CallExpr)
  3656  		if ir.IsIntrinsicCall(n) {
  3657  			return s.intrinsicCall(n)
  3658  		}
  3659  		fallthrough
  3660  
  3661  	case ir.OCALLINTER:
  3662  		n := n.(*ir.CallExpr)
  3663  		return s.callResult(n, callNormal)
  3664  
  3665  	case ir.OGETG:
  3666  		n := n.(*ir.CallExpr)
  3667  		return s.newValue1(ssa.OpGetG, n.Type(), s.mem())
  3668  
  3669  	case ir.OGETCALLERSP:
  3670  		n := n.(*ir.CallExpr)
  3671  		return s.newValue1(ssa.OpGetCallerSP, n.Type(), s.mem())
  3672  
  3673  	case ir.OAPPEND:
  3674  		return s.append(n.(*ir.CallExpr), false)
  3675  
  3676  	case ir.OMIN, ir.OMAX:
  3677  		return s.minMax(n.(*ir.CallExpr))
  3678  
  3679  	case ir.OSTRUCTLIT, ir.OARRAYLIT:
  3680  		// All literals with nonzero fields have already been
  3681  		// rewritten during walk. Any that remain are just T{}
  3682  		// or equivalents. Use the zero value.
  3683  		n := n.(*ir.CompLitExpr)
  3684  		if !ir.IsZero(n) {
  3685  			s.Fatalf("literal with nonzero value in SSA: %v", n)
  3686  		}
  3687  		return s.zeroVal(n.Type())
  3688  
  3689  	case ir.ONEW:
  3690  		n := n.(*ir.UnaryExpr)
  3691  		if x, ok := n.X.(*ir.DynamicType); ok && x.Op() == ir.ODYNAMICTYPE {
  3692  			return s.newObjectNonSpecialized(n.Type().Elem(), s.expr(x.RType))
  3693  		}
  3694  		return s.newObject(n.Type().Elem())
  3695  
  3696  	case ir.OUNSAFEADD:
  3697  		n := n.(*ir.BinaryExpr)
  3698  		ptr := s.expr(n.X)
  3699  		len := s.expr(n.Y)
  3700  
  3701  		// Force len to uintptr to prevent misuse of garbage bits in the
  3702  		// upper part of the register (#48536).
  3703  		len = s.conv(n, len, len.Type, types.Types[types.TUINTPTR])
  3704  
  3705  		return s.newValue2(ssa.OpAddPtr, n.Type(), ptr, len)
  3706  
  3707  	default:
  3708  		s.Fatalf("unhandled expr %v", n.Op())
  3709  		return nil
  3710  	}
  3711  }
  3712  
  3713  func (s *state) resultOfCall(c *ssa.Value, which int64, t *types.Type) *ssa.Value {
  3714  	aux := c.Aux.(*ssa.AuxCall)
  3715  	pa := aux.ParamAssignmentForResult(which)
  3716  	// TODO(register args) determine if in-memory TypeOK is better loaded early from SelectNAddr or later when SelectN is expanded.
  3717  	// SelectN is better for pattern-matching and possible call-aware analysis we might want to do in the future.
  3718  	if len(pa.Registers) == 0 && !ssa.CanSSA(t) {
  3719  		addr := s.newValue1I(ssa.OpSelectNAddr, types.NewPtr(t), which, c)
  3720  		return s.rawLoad(t, addr)
  3721  	}
  3722  	return s.newValue1I(ssa.OpSelectN, t, which, c)
  3723  }
  3724  
  3725  func (s *state) resultAddrOfCall(c *ssa.Value, which int64, t *types.Type) *ssa.Value {
  3726  	aux := c.Aux.(*ssa.AuxCall)
  3727  	pa := aux.ParamAssignmentForResult(which)
  3728  	if len(pa.Registers) == 0 {
  3729  		return s.newValue1I(ssa.OpSelectNAddr, types.NewPtr(t), which, c)
  3730  	}
  3731  	_, addr := s.temp(c.Pos, t)
  3732  	rval := s.newValue1I(ssa.OpSelectN, t, which, c)
  3733  	s.vars[memVar] = s.newValue3Apos(ssa.OpStore, types.TypeMem, t, addr, rval, s.mem(), false)
  3734  	return addr
  3735  }
  3736  
  3737  // append converts an OAPPEND node to SSA.
  3738  // If inplace is false, it converts the OAPPEND expression n to an ssa.Value,
  3739  // adds it to s, and returns the Value.
  3740  // If inplace is true, it writes the result of the OAPPEND expression n
  3741  // back to the slice being appended to, and returns nil.
  3742  // inplace MUST be set to false if the slice can be SSA'd.
  3743  // Note: this code only handles fixed-count appends. Dotdotdot appends
  3744  // have already been rewritten at this point (by walk).
  3745  func (s *state) append(n *ir.CallExpr, inplace bool) *ssa.Value {
  3746  	// If inplace is false, process as expression "append(s, e1, e2, e3)":
  3747  	//
  3748  	// ptr, len, cap := s
  3749  	// len += 3
  3750  	// if uint(len) > uint(cap) {
  3751  	//     ptr, len, cap = growslice(ptr, len, cap, 3, typ)
  3752  	//     Note that len is unmodified by growslice.
  3753  	// }
  3754  	// // with write barriers, if needed:
  3755  	// *(ptr+(len-3)) = e1
  3756  	// *(ptr+(len-2)) = e2
  3757  	// *(ptr+(len-1)) = e3
  3758  	// return makeslice(ptr, len, cap)
  3759  	//
  3760  	//
  3761  	// If inplace is true, process as statement "s = append(s, e1, e2, e3)":
  3762  	//
  3763  	// a := &s
  3764  	// ptr, len, cap := s
  3765  	// len += 3
  3766  	// if uint(len) > uint(cap) {
  3767  	//    ptr, len, cap = growslice(ptr, len, cap, 3, typ)
  3768  	//    vardef(a)    // if necessary, advise liveness we are writing a new a
  3769  	//    *a.cap = cap // write before ptr to avoid a spill
  3770  	//    *a.ptr = ptr // with write barrier
  3771  	// }
  3772  	// *a.len = len
  3773  	// // with write barriers, if needed:
  3774  	// *(ptr+(len-3)) = e1
  3775  	// *(ptr+(len-2)) = e2
  3776  	// *(ptr+(len-1)) = e3
  3777  
  3778  	et := n.Type().Elem()
  3779  	pt := types.NewPtr(et)
  3780  
  3781  	// Evaluate slice
  3782  	sn := n.Args[0] // the slice node is the first in the list
  3783  	var slice, addr *ssa.Value
  3784  	if inplace {
  3785  		addr = s.addr(sn)
  3786  		slice = s.load(n.Type(), addr)
  3787  	} else {
  3788  		slice = s.expr(sn)
  3789  	}
  3790  
  3791  	// Allocate new blocks
  3792  	grow := s.f.NewBlock(ssa.BlockPlain)
  3793  	assign := s.f.NewBlock(ssa.BlockPlain)
  3794  
  3795  	// Decomposse input slice.
  3796  	p := s.newValue1(ssa.OpSlicePtr, pt, slice)
  3797  	l := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], slice)
  3798  	c := s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], slice)
  3799  
  3800  	// Add number of new elements to length.
  3801  	nargs := s.constInt(types.Types[types.TINT], int64(len(n.Args)-1))
  3802  	oldLen := l
  3803  	l = s.newValue2(s.ssaOp(ir.OADD, types.Types[types.TINT]), types.Types[types.TINT], l, nargs)
  3804  
  3805  	// Decide if we need to grow
  3806  	cmp := s.newValue2(s.ssaOp(ir.OLT, types.Types[types.TUINT]), types.Types[types.TBOOL], c, l)
  3807  
  3808  	// Record values of ptr/len/cap before branch.
  3809  	s.vars[ptrVar] = p
  3810  	s.vars[lenVar] = l
  3811  	if !inplace {
  3812  		s.vars[capVar] = c
  3813  	}
  3814  
  3815  	b := s.endBlock()
  3816  	b.Kind = ssa.BlockIf
  3817  	b.Likely = ssa.BranchUnlikely
  3818  	b.SetControl(cmp)
  3819  	b.AddEdgeTo(grow)
  3820  	b.AddEdgeTo(assign)
  3821  
  3822  	// If the result of the append does not escape, we can use
  3823  	// a stack-allocated backing store if len is small enough.
  3824  	// A stack-allocated backing store could be used at every
  3825  	// append that qualifies, but we limit it in some cases to
  3826  	// avoid wasted code and stack space.
  3827  	// TODO: handle ... append case.
  3828  	maxStackSize := int64(base.Debug.VariableMakeThreshold)
  3829  	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] {
  3830  		// if l <= K {
  3831  		//   if !used {
  3832  		//     if oldLen == 0 {
  3833  		//       var store [K]T
  3834  		//       s = store[:l:K]
  3835  		//       used = true
  3836  		//     }
  3837  		//   }
  3838  		// }
  3839  		// ... if we didn't use the stack backing store, call growslice ...
  3840  		//
  3841  		// oldLen==0 is not strictly necessary, but requiring it means
  3842  		// we don't have to worry about copying existing elements.
  3843  		// Allowing oldLen>0 would add complication. Worth it? I would guess not.
  3844  		//
  3845  		// TODO: instead of the used boolean, we could insist that this only applies
  3846  		// to monotonic slices, those which once they have >0 entries never go back
  3847  		// to 0 entries. Then oldLen==0 is enough.
  3848  		//
  3849  		// We also do this for append(x, ...) once for every x.
  3850  		// It is ok to do it more often, but it is probably helpful only for
  3851  		// the first instance. TODO: this could use more tuning. Using ir.Node
  3852  		// as the key works for *ir.Name instances but probably nothing else.
  3853  		if s.appendTargets == nil {
  3854  			s.appendTargets = map[ir.Node]bool{}
  3855  		}
  3856  		s.appendTargets[sn] = true
  3857  
  3858  		K := maxStackSize / et.Size() // rounds down
  3859  		KT := types.NewArray(et, K)
  3860  		KT.SetNoalg(true)
  3861  		types.CalcArraySize(KT)
  3862  		// Align more than naturally for the type KT. See issue 73199.
  3863  		align := types.NewArray(types.Types[types.TUINTPTR], 0)
  3864  		types.CalcArraySize(align)
  3865  		storeTyp := types.NewStruct([]*types.Field{
  3866  			{Sym: types.BlankSym, Type: align},
  3867  			{Sym: types.BlankSym, Type: KT},
  3868  		})
  3869  		storeTyp.SetNoalg(true)
  3870  		types.CalcStructSize(storeTyp)
  3871  
  3872  		usedTestBlock := s.f.NewBlock(ssa.BlockPlain)
  3873  		oldLenTestBlock := s.f.NewBlock(ssa.BlockPlain)
  3874  		bodyBlock := s.f.NewBlock(ssa.BlockPlain)
  3875  		growSlice := s.f.NewBlock(ssa.BlockPlain)
  3876  
  3877  		// Make "used" boolean.
  3878  		tBool := types.Types[types.TBOOL]
  3879  		used := typecheck.TempAt(n.Pos(), s.curfn, tBool)
  3880  		s.defvars[s.f.Entry.ID][used] = s.constBool(false) // initialize this variable at fn entry
  3881  
  3882  		// Make backing store variable.
  3883  		tInt := types.Types[types.TINT]
  3884  		backingStore := typecheck.TempAt(n.Pos(), s.curfn, storeTyp)
  3885  		backingStore.SetAddrtaken(true)
  3886  
  3887  		// if l <= K
  3888  		s.startBlock(grow)
  3889  		kTest := s.newValue2(s.ssaOp(ir.OLE, tInt), tBool, l, s.constInt(tInt, K))
  3890  		b := s.endBlock()
  3891  		b.Kind = ssa.BlockIf
  3892  		b.SetControl(kTest)
  3893  		b.AddEdgeTo(usedTestBlock)
  3894  		b.AddEdgeTo(growSlice)
  3895  		b.Likely = ssa.BranchLikely
  3896  
  3897  		// if !used
  3898  		s.startBlock(usedTestBlock)
  3899  		usedTest := s.newValue1(ssa.OpNot, tBool, s.expr(used))
  3900  		b = s.endBlock()
  3901  		b.Kind = ssa.BlockIf
  3902  		b.SetControl(usedTest)
  3903  		b.AddEdgeTo(oldLenTestBlock)
  3904  		b.AddEdgeTo(growSlice)
  3905  		b.Likely = ssa.BranchLikely
  3906  
  3907  		// if oldLen == 0
  3908  		s.startBlock(oldLenTestBlock)
  3909  		oldLenTest := s.newValue2(s.ssaOp(ir.OEQ, tInt), tBool, oldLen, s.constInt(tInt, 0))
  3910  		b = s.endBlock()
  3911  		b.Kind = ssa.BlockIf
  3912  		b.SetControl(oldLenTest)
  3913  		b.AddEdgeTo(bodyBlock)
  3914  		b.AddEdgeTo(growSlice)
  3915  		b.Likely = ssa.BranchLikely
  3916  
  3917  		// var store struct { _ [0]uintptr; arr [K]T }
  3918  		s.startBlock(bodyBlock)
  3919  		if et.HasPointers() {
  3920  			s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, backingStore, s.mem())
  3921  		}
  3922  		addr := s.addr(backingStore)
  3923  		s.zero(storeTyp, addr)
  3924  
  3925  		// s = store.arr[:l:K]
  3926  		s.vars[ptrVar] = addr
  3927  		s.vars[lenVar] = l // nargs would also be ok because of the oldLen==0 test.
  3928  		s.vars[capVar] = s.constInt(tInt, K)
  3929  
  3930  		// used = true
  3931  		s.assign(used, s.constBool(true), false, 0)
  3932  		b = s.endBlock()
  3933  		b.AddEdgeTo(assign)
  3934  
  3935  		// New block to use for growslice call.
  3936  		grow = growSlice
  3937  	}
  3938  
  3939  	// Call growslice
  3940  	s.startBlock(grow)
  3941  	taddr := s.expr(n.Fun)
  3942  	r := s.rtcall(ir.Syms.Growslice, true, []*types.Type{n.Type()}, p, l, c, nargs, taddr)
  3943  
  3944  	// Decompose output slice
  3945  	p = s.newValue1(ssa.OpSlicePtr, pt, r[0])
  3946  	l = s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], r[0])
  3947  	c = s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], r[0])
  3948  
  3949  	s.vars[ptrVar] = p
  3950  	s.vars[lenVar] = l
  3951  	s.vars[capVar] = c
  3952  	if inplace {
  3953  		if sn.Op() == ir.ONAME {
  3954  			sn := sn.(*ir.Name)
  3955  			if sn.Class != ir.PEXTERN {
  3956  				// Tell liveness we're about to build a new slice
  3957  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, sn, s.mem())
  3958  			}
  3959  		}
  3960  		capaddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, types.SliceCapOffset, addr)
  3961  		s.store(types.Types[types.TINT], capaddr, c)
  3962  		s.store(pt, addr, p)
  3963  	}
  3964  
  3965  	b = s.endBlock()
  3966  	b.AddEdgeTo(assign)
  3967  
  3968  	// assign new elements to slots
  3969  	s.startBlock(assign)
  3970  	p = s.variable(ptrVar, pt)                      // generates phi for ptr
  3971  	l = s.variable(lenVar, types.Types[types.TINT]) // generates phi for len
  3972  	if !inplace {
  3973  		c = s.variable(capVar, types.Types[types.TINT]) // generates phi for cap
  3974  	}
  3975  
  3976  	if inplace {
  3977  		// Update length in place.
  3978  		// We have to wait until here to make sure growslice succeeded.
  3979  		lenaddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, types.SliceLenOffset, addr)
  3980  		s.store(types.Types[types.TINT], lenaddr, l)
  3981  	}
  3982  
  3983  	// Evaluate args
  3984  	type argRec struct {
  3985  		// if store is true, we're appending the value v.  If false, we're appending the
  3986  		// value at *v.
  3987  		v     *ssa.Value
  3988  		store bool
  3989  	}
  3990  	args := make([]argRec, 0, len(n.Args[1:]))
  3991  	for _, n := range n.Args[1:] {
  3992  		if ssa.CanSSA(n.Type()) {
  3993  			args = append(args, argRec{v: s.expr(n), store: true})
  3994  		} else {
  3995  			v := s.addr(n)
  3996  			args = append(args, argRec{v: v})
  3997  		}
  3998  	}
  3999  
  4000  	// Write args into slice.
  4001  	oldLen = s.newValue2(s.ssaOp(ir.OSUB, types.Types[types.TINT]), types.Types[types.TINT], l, nargs)
  4002  	p2 := s.newValue2(ssa.OpPtrIndex, pt, p, oldLen)
  4003  	for i, arg := range args {
  4004  		addr := s.newValue2(ssa.OpPtrIndex, pt, p2, s.constInt(types.Types[types.TINT], int64(i)))
  4005  		if arg.store {
  4006  			s.storeType(et, addr, arg.v, 0, true)
  4007  		} else {
  4008  			s.move(et, addr, arg.v)
  4009  		}
  4010  	}
  4011  
  4012  	// The following deletions have no practical effect at this time
  4013  	// because state.vars has been reset by the preceding state.startBlock.
  4014  	// They only enforce the fact that these variables are no longer need in
  4015  	// the current scope.
  4016  	delete(s.vars, ptrVar)
  4017  	delete(s.vars, lenVar)
  4018  	if !inplace {
  4019  		delete(s.vars, capVar)
  4020  	}
  4021  
  4022  	// make result
  4023  	if inplace {
  4024  		return nil
  4025  	}
  4026  	return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)
  4027  }
  4028  
  4029  // minMax converts an OMIN/OMAX builtin call into SSA.
  4030  func (s *state) minMax(n *ir.CallExpr) *ssa.Value {
  4031  	// The OMIN/OMAX builtin is variadic, but its semantics are
  4032  	// equivalent to left-folding a binary min/max operation across the
  4033  	// arguments list.
  4034  	fold := func(op func(x, a *ssa.Value) *ssa.Value) *ssa.Value {
  4035  		x := s.expr(n.Args[0])
  4036  		for _, arg := range n.Args[1:] {
  4037  			x = op(x, s.expr(arg))
  4038  		}
  4039  		return x
  4040  	}
  4041  
  4042  	typ := n.Type()
  4043  
  4044  	if typ.IsFloat() || typ.IsString() {
  4045  		// min/max semantics for floats are tricky because of NaNs and
  4046  		// negative zero. Some architectures have instructions which
  4047  		// we can use to generate the right result. For others we must
  4048  		// call into the runtime instead.
  4049  		//
  4050  		// Strings are conceptually simpler, but we currently desugar
  4051  		// string comparisons during walk, not ssagen.
  4052  
  4053  		if typ.IsFloat() {
  4054  			hasIntrinsic := false
  4055  			switch Arch.LinkArch.Family {
  4056  			case sys.AMD64, sys.ARM64, sys.Loong64, sys.RISCV64, sys.S390X:
  4057  				hasIntrinsic = true
  4058  			case sys.PPC64:
  4059  				hasIntrinsic = buildcfg.GOPPC64 >= 9
  4060  			}
  4061  
  4062  			if hasIntrinsic {
  4063  				var op ssa.Op
  4064  				switch {
  4065  				case typ.Kind() == types.TFLOAT64 && n.Op() == ir.OMIN:
  4066  					op = ssa.OpMin64F
  4067  				case typ.Kind() == types.TFLOAT64 && n.Op() == ir.OMAX:
  4068  					op = ssa.OpMax64F
  4069  				case typ.Kind() == types.TFLOAT32 && n.Op() == ir.OMIN:
  4070  					op = ssa.OpMin32F
  4071  				case typ.Kind() == types.TFLOAT32 && n.Op() == ir.OMAX:
  4072  					op = ssa.OpMax32F
  4073  				}
  4074  				return fold(func(x, a *ssa.Value) *ssa.Value {
  4075  					return s.newValue2(op, typ, x, a)
  4076  				})
  4077  			}
  4078  		}
  4079  		var name string
  4080  		switch typ.Kind() {
  4081  		case types.TFLOAT32:
  4082  			switch n.Op() {
  4083  			case ir.OMIN:
  4084  				name = "fmin32"
  4085  			case ir.OMAX:
  4086  				name = "fmax32"
  4087  			}
  4088  		case types.TFLOAT64:
  4089  			switch n.Op() {
  4090  			case ir.OMIN:
  4091  				name = "fmin64"
  4092  			case ir.OMAX:
  4093  				name = "fmax64"
  4094  			}
  4095  		case types.TSTRING:
  4096  			switch n.Op() {
  4097  			case ir.OMIN:
  4098  				name = "strmin"
  4099  			case ir.OMAX:
  4100  				name = "strmax"
  4101  			}
  4102  		}
  4103  		fn := typecheck.LookupRuntimeFunc(name)
  4104  
  4105  		return fold(func(x, a *ssa.Value) *ssa.Value {
  4106  			return s.rtcall(fn, true, []*types.Type{typ}, x, a)[0]
  4107  		})
  4108  	}
  4109  
  4110  	if typ.IsInteger() {
  4111  		if Arch.LinkArch.Family == sys.RISCV64 && buildcfg.GORISCV64 >= 22 && typ.Size() == 8 {
  4112  			var op ssa.Op
  4113  			switch {
  4114  			case typ.IsSigned() && n.Op() == ir.OMIN:
  4115  				op = ssa.OpMin64
  4116  			case typ.IsSigned() && n.Op() == ir.OMAX:
  4117  				op = ssa.OpMax64
  4118  			case typ.IsUnsigned() && n.Op() == ir.OMIN:
  4119  				op = ssa.OpMin64u
  4120  			case typ.IsUnsigned() && n.Op() == ir.OMAX:
  4121  				op = ssa.OpMax64u
  4122  			}
  4123  			return fold(func(x, a *ssa.Value) *ssa.Value {
  4124  				return s.newValue2(op, typ, x, a)
  4125  			})
  4126  		}
  4127  	}
  4128  
  4129  	lt := s.ssaOp(ir.OLT, typ)
  4130  
  4131  	return fold(func(x, a *ssa.Value) *ssa.Value {
  4132  		switch n.Op() {
  4133  		case ir.OMIN:
  4134  			// a < x ? a : x
  4135  			return s.ternary(s.newValue2(lt, types.Types[types.TBOOL], a, x), a, x)
  4136  		case ir.OMAX:
  4137  			// x < a ? a : x
  4138  			return s.ternary(s.newValue2(lt, types.Types[types.TBOOL], x, a), a, x)
  4139  		}
  4140  		panic("unreachable")
  4141  	})
  4142  }
  4143  
  4144  // ternary emits code to evaluate cond ? x : y.
  4145  func (s *state) ternary(cond, x, y *ssa.Value) *ssa.Value {
  4146  	// Note that we need a new ternaryVar each time (unlike okVar where we can
  4147  	// reuse the variable) because it might have a different type every time.
  4148  	ternaryVar := ssaMarker("ternary")
  4149  
  4150  	bThen := s.f.NewBlock(ssa.BlockPlain)
  4151  	bElse := s.f.NewBlock(ssa.BlockPlain)
  4152  	bEnd := s.f.NewBlock(ssa.BlockPlain)
  4153  
  4154  	b := s.endBlock()
  4155  	b.Kind = ssa.BlockIf
  4156  	b.SetControl(cond)
  4157  	b.AddEdgeTo(bThen)
  4158  	b.AddEdgeTo(bElse)
  4159  
  4160  	s.startBlock(bThen)
  4161  	s.vars[ternaryVar] = x
  4162  	s.endBlock().AddEdgeTo(bEnd)
  4163  
  4164  	s.startBlock(bElse)
  4165  	s.vars[ternaryVar] = y
  4166  	s.endBlock().AddEdgeTo(bEnd)
  4167  
  4168  	s.startBlock(bEnd)
  4169  	r := s.variable(ternaryVar, x.Type)
  4170  	delete(s.vars, ternaryVar)
  4171  	return r
  4172  }
  4173  
  4174  // condBranch evaluates the boolean expression cond and branches to yes
  4175  // if cond is true and no if cond is false.
  4176  // This function is intended to handle && and || better than just calling
  4177  // s.expr(cond) and branching on the result.
  4178  func (s *state) condBranch(cond ir.Node, yes, no *ssa.Block, likely int8) {
  4179  	switch cond.Op() {
  4180  	case ir.OANDAND:
  4181  		cond := cond.(*ir.LogicalExpr)
  4182  		mid := s.f.NewBlock(ssa.BlockPlain)
  4183  		s.stmtList(cond.Init())
  4184  		s.condBranch(cond.X, mid, no, max(likely, 0))
  4185  		s.startBlock(mid)
  4186  		s.condBranch(cond.Y, yes, no, likely)
  4187  		return
  4188  		// Note: if likely==1, then both recursive calls pass 1.
  4189  		// If likely==-1, then we don't have enough information to decide
  4190  		// whether the first branch is likely or not. So we pass 0 for
  4191  		// the likeliness of the first branch.
  4192  		// TODO: have the frontend give us branch prediction hints for
  4193  		// OANDAND and OOROR nodes (if it ever has such info).
  4194  	case ir.OOROR:
  4195  		cond := cond.(*ir.LogicalExpr)
  4196  		mid := s.f.NewBlock(ssa.BlockPlain)
  4197  		s.stmtList(cond.Init())
  4198  		s.condBranch(cond.X, yes, mid, min(likely, 0))
  4199  		s.startBlock(mid)
  4200  		s.condBranch(cond.Y, yes, no, likely)
  4201  		return
  4202  		// Note: if likely==-1, then both recursive calls pass -1.
  4203  		// If likely==1, then we don't have enough info to decide
  4204  		// the likelihood of the first branch.
  4205  	case ir.ONOT:
  4206  		cond := cond.(*ir.UnaryExpr)
  4207  		s.stmtList(cond.Init())
  4208  		s.condBranch(cond.X, no, yes, -likely)
  4209  		return
  4210  	case ir.OCONVNOP:
  4211  		cond := cond.(*ir.ConvExpr)
  4212  		s.stmtList(cond.Init())
  4213  		s.condBranch(cond.X, yes, no, likely)
  4214  		return
  4215  	}
  4216  	c := s.expr(cond)
  4217  	b := s.endBlock()
  4218  	b.Kind = ssa.BlockIf
  4219  	b.SetControl(c)
  4220  	b.Likely = ssa.BranchPrediction(likely) // gc and ssa both use -1/0/+1 for likeliness
  4221  	b.AddEdgeTo(yes)
  4222  	b.AddEdgeTo(no)
  4223  }
  4224  
  4225  type skipMask uint8
  4226  
  4227  const (
  4228  	skipPtr skipMask = 1 << iota
  4229  	skipLen
  4230  	skipCap
  4231  )
  4232  
  4233  // assign does left = right.
  4234  // Right has already been evaluated to ssa, left has not.
  4235  // If deref is true, then we do left = *right instead (and right has already been nil-checked).
  4236  // If deref is true and right == nil, just do left = 0.
  4237  // skip indicates assignments (at the top level) that can be avoided.
  4238  // mayOverlap indicates whether left&right might partially overlap in memory. Default is false.
  4239  func (s *state) assign(left ir.Node, right *ssa.Value, deref bool, skip skipMask) {
  4240  	s.assignWhichMayOverlap(left, right, deref, skip, false)
  4241  }
  4242  func (s *state) assignWhichMayOverlap(left ir.Node, right *ssa.Value, deref bool, skip skipMask, mayOverlap bool) {
  4243  	if left.Op() == ir.ONAME && ir.IsBlank(left) {
  4244  		return
  4245  	}
  4246  	t := left.Type()
  4247  	types.CalcSize(t)
  4248  	if s.canSSA(left) {
  4249  		if deref {
  4250  			s.Fatalf("can SSA LHS %v but not RHS %s", left, right)
  4251  		}
  4252  		if left.Op() == ir.ODOT {
  4253  			// We're assigning to a field of an ssa-able value.
  4254  			// We need to build a new structure with the new value for the
  4255  			// field we're assigning and the old values for the other fields.
  4256  			// For instance:
  4257  			//   type T struct {a, b, c int}
  4258  			//   var T x
  4259  			//   x.b = 5
  4260  			// For the x.b = 5 assignment we want to generate x = T{x.a, 5, x.c}
  4261  
  4262  			// Grab information about the structure type.
  4263  			left := left.(*ir.SelectorExpr)
  4264  			t := left.X.Type()
  4265  			nf := t.NumFields()
  4266  			idx := fieldIdx(left)
  4267  
  4268  			// Grab old value of structure.
  4269  			old := s.expr(left.X)
  4270  
  4271  			// Make new structure.
  4272  			new := s.newValue0(ssa.OpStructMake, t)
  4273  
  4274  			// Add fields as args.
  4275  			for i := 0; i < nf; i++ {
  4276  				if i == idx {
  4277  					new.AddArg(right)
  4278  				} else {
  4279  					new.AddArg(s.newValue1I(ssa.OpStructSelect, t.FieldType(i), int64(i), old))
  4280  				}
  4281  			}
  4282  
  4283  			// Recursively assign the new value we've made to the base of the dot op.
  4284  			s.assign(left.X, new, false, 0)
  4285  			// TODO: do we need to update named values here?
  4286  			return
  4287  		}
  4288  		if left.Op() == ir.OINDEX && left.(*ir.IndexExpr).X.Type().IsArray() {
  4289  			left := left.(*ir.IndexExpr)
  4290  			s.pushLine(left.Pos())
  4291  			defer s.popLine()
  4292  			// We're assigning to an element of an ssa-able array.
  4293  			// a[i] = v
  4294  			t := left.X.Type()
  4295  			n := t.NumElem()
  4296  
  4297  			i := s.expr(left.Index) // index
  4298  			if n == 0 {
  4299  				// The bounds check must fail.  Might as well
  4300  				// ignore the actual index and just use zeros.
  4301  				z := s.constInt(types.Types[types.TINT], 0)
  4302  				s.boundsCheck(z, z, ssa.BoundsIndex, false)
  4303  				return
  4304  			}
  4305  			if n != 1 {
  4306  				s.Fatalf("assigning to non-1-length array")
  4307  			}
  4308  			// Rewrite to a = [1]{v}
  4309  			len := s.constInt(types.Types[types.TINT], 1)
  4310  			s.boundsCheck(i, len, ssa.BoundsIndex, false) // checks i == 0
  4311  			v := s.newValue1(ssa.OpArrayMake1, t, right)
  4312  			s.assign(left.X, v, false, 0)
  4313  			return
  4314  		}
  4315  		left := left.(*ir.Name)
  4316  		// Update variable assignment.
  4317  		s.vars[left] = right
  4318  		s.addNamedValue(left, right)
  4319  		return
  4320  	}
  4321  
  4322  	// If this assignment clobbers an entire local variable, then emit
  4323  	// OpVarDef so liveness analysis knows the variable is redefined.
  4324  	if base, ok := clobberBase(left).(*ir.Name); ok && base.OnStack() && skip == 0 && (t.HasPointers() || ssa.IsMergeCandidate(base)) {
  4325  		s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, base, s.mem(), !ir.IsAutoTmp(base))
  4326  	}
  4327  
  4328  	// Left is not ssa-able. Compute its address.
  4329  	addr := s.addr(left)
  4330  	if ir.IsReflectHeaderDataField(left) {
  4331  		// Package unsafe's documentation says storing pointers into
  4332  		// reflect.SliceHeader and reflect.StringHeader's Data fields
  4333  		// is valid, even though they have type uintptr (#19168).
  4334  		// Mark it pointer type to signal the writebarrier pass to
  4335  		// insert a write barrier.
  4336  		t = types.Types[types.TUNSAFEPTR]
  4337  	}
  4338  	if deref {
  4339  		// Treat as a mem->mem move.
  4340  		if right == nil {
  4341  			s.zero(t, addr)
  4342  		} else {
  4343  			s.moveWhichMayOverlap(t, addr, right, mayOverlap)
  4344  		}
  4345  		return
  4346  	}
  4347  	// Treat as a store.
  4348  	s.storeType(t, addr, right, skip, !ir.IsAutoTmp(left))
  4349  }
  4350  
  4351  // zeroVal returns the zero value for type t.
  4352  func (s *state) zeroVal(t *types.Type) *ssa.Value {
  4353  	switch {
  4354  	case t.IsInteger():
  4355  		switch t.Size() {
  4356  		case 1:
  4357  			return s.constInt8(t, 0)
  4358  		case 2:
  4359  			return s.constInt16(t, 0)
  4360  		case 4:
  4361  			return s.constInt32(t, 0)
  4362  		case 8:
  4363  			return s.constInt64(t, 0)
  4364  		default:
  4365  			s.Fatalf("bad sized integer type %v", t)
  4366  		}
  4367  	case t.IsFloat():
  4368  		switch t.Size() {
  4369  		case 4:
  4370  			return s.constFloat32(t, 0)
  4371  		case 8:
  4372  			return s.constFloat64(t, 0)
  4373  		default:
  4374  			s.Fatalf("bad sized float type %v", t)
  4375  		}
  4376  	case t.IsComplex():
  4377  		switch t.Size() {
  4378  		case 8:
  4379  			z := s.constFloat32(types.Types[types.TFLOAT32], 0)
  4380  			return s.entryNewValue2(ssa.OpComplexMake, t, z, z)
  4381  		case 16:
  4382  			z := s.constFloat64(types.Types[types.TFLOAT64], 0)
  4383  			return s.entryNewValue2(ssa.OpComplexMake, t, z, z)
  4384  		default:
  4385  			s.Fatalf("bad sized complex type %v", t)
  4386  		}
  4387  
  4388  	case t.IsString():
  4389  		return s.constEmptyString(t)
  4390  	case t.IsPtrShaped():
  4391  		return s.constNil(t)
  4392  	case t.IsBoolean():
  4393  		return s.constBool(false)
  4394  	case t.IsInterface():
  4395  		return s.constInterface(t)
  4396  	case t.IsSlice():
  4397  		return s.constSlice(t)
  4398  	case t.IsStruct():
  4399  		n := t.NumFields()
  4400  		v := s.entryNewValue0(ssa.OpStructMake, t)
  4401  		for i := 0; i < n; i++ {
  4402  			v.AddArg(s.zeroVal(t.FieldType(i)))
  4403  		}
  4404  		return v
  4405  	case t.IsArray():
  4406  		switch t.NumElem() {
  4407  		case 0:
  4408  			return s.entryNewValue0(ssa.OpArrayMake0, t)
  4409  		case 1:
  4410  			return s.entryNewValue1(ssa.OpArrayMake1, t, s.zeroVal(t.Elem()))
  4411  		}
  4412  	}
  4413  	s.Fatalf("zero for type %v not implemented", t)
  4414  	return nil
  4415  }
  4416  
  4417  type callKind int8
  4418  
  4419  const (
  4420  	callNormal callKind = iota
  4421  	callDefer
  4422  	callDeferStack
  4423  	callGo
  4424  	callTail
  4425  )
  4426  
  4427  type sfRtCallDef struct {
  4428  	rtfn  *obj.LSym
  4429  	rtype types.Kind
  4430  }
  4431  
  4432  var softFloatOps map[ssa.Op]sfRtCallDef
  4433  
  4434  func softfloatInit() {
  4435  	// Some of these operations get transformed by sfcall.
  4436  	softFloatOps = map[ssa.Op]sfRtCallDef{
  4437  		ssa.OpAdd32F: {typecheck.LookupRuntimeFunc("fadd32"), types.TFLOAT32},
  4438  		ssa.OpAdd64F: {typecheck.LookupRuntimeFunc("fadd64"), types.TFLOAT64},
  4439  		ssa.OpSub32F: {typecheck.LookupRuntimeFunc("fadd32"), types.TFLOAT32},
  4440  		ssa.OpSub64F: {typecheck.LookupRuntimeFunc("fadd64"), types.TFLOAT64},
  4441  		ssa.OpMul32F: {typecheck.LookupRuntimeFunc("fmul32"), types.TFLOAT32},
  4442  		ssa.OpMul64F: {typecheck.LookupRuntimeFunc("fmul64"), types.TFLOAT64},
  4443  		ssa.OpDiv32F: {typecheck.LookupRuntimeFunc("fdiv32"), types.TFLOAT32},
  4444  		ssa.OpDiv64F: {typecheck.LookupRuntimeFunc("fdiv64"), types.TFLOAT64},
  4445  
  4446  		ssa.OpEq64F:   {typecheck.LookupRuntimeFunc("feq64"), types.TBOOL},
  4447  		ssa.OpEq32F:   {typecheck.LookupRuntimeFunc("feq32"), types.TBOOL},
  4448  		ssa.OpNeq64F:  {typecheck.LookupRuntimeFunc("feq64"), types.TBOOL},
  4449  		ssa.OpNeq32F:  {typecheck.LookupRuntimeFunc("feq32"), types.TBOOL},
  4450  		ssa.OpLess64F: {typecheck.LookupRuntimeFunc("fgt64"), types.TBOOL},
  4451  		ssa.OpLess32F: {typecheck.LookupRuntimeFunc("fgt32"), types.TBOOL},
  4452  		ssa.OpLeq64F:  {typecheck.LookupRuntimeFunc("fge64"), types.TBOOL},
  4453  		ssa.OpLeq32F:  {typecheck.LookupRuntimeFunc("fge32"), types.TBOOL},
  4454  
  4455  		ssa.OpCvt32to32F:  {typecheck.LookupRuntimeFunc("fint32to32"), types.TFLOAT32},
  4456  		ssa.OpCvt32Fto32:  {typecheck.LookupRuntimeFunc("f32toint32"), types.TINT32},
  4457  		ssa.OpCvt64to32F:  {typecheck.LookupRuntimeFunc("fint64to32"), types.TFLOAT32},
  4458  		ssa.OpCvt32Fto64:  {typecheck.LookupRuntimeFunc("f32toint64"), types.TINT64},
  4459  		ssa.OpCvt64Uto32F: {typecheck.LookupRuntimeFunc("fuint64to32"), types.TFLOAT32},
  4460  		ssa.OpCvt32Fto64U: {typecheck.LookupRuntimeFunc("f32touint64"), types.TUINT64},
  4461  		ssa.OpCvt32to64F:  {typecheck.LookupRuntimeFunc("fint32to64"), types.TFLOAT64},
  4462  		ssa.OpCvt64Fto32:  {typecheck.LookupRuntimeFunc("f64toint32"), types.TINT32},
  4463  		ssa.OpCvt64to64F:  {typecheck.LookupRuntimeFunc("fint64to64"), types.TFLOAT64},
  4464  		ssa.OpCvt64Fto64:  {typecheck.LookupRuntimeFunc("f64toint64"), types.TINT64},
  4465  		ssa.OpCvt64Uto64F: {typecheck.LookupRuntimeFunc("fuint64to64"), types.TFLOAT64},
  4466  		ssa.OpCvt64Fto64U: {typecheck.LookupRuntimeFunc("f64touint64"), types.TUINT64},
  4467  		ssa.OpCvt32Fto64F: {typecheck.LookupRuntimeFunc("f32to64"), types.TFLOAT64},
  4468  		ssa.OpCvt64Fto32F: {typecheck.LookupRuntimeFunc("f64to32"), types.TFLOAT32},
  4469  	}
  4470  }
  4471  
  4472  // TODO: do not emit sfcall if operation can be optimized to constant in later
  4473  // opt phase
  4474  func (s *state) sfcall(op ssa.Op, args ...*ssa.Value) (*ssa.Value, bool) {
  4475  	f2i := func(t *types.Type) *types.Type {
  4476  		switch t.Kind() {
  4477  		case types.TFLOAT32:
  4478  			return types.Types[types.TUINT32]
  4479  		case types.TFLOAT64:
  4480  			return types.Types[types.TUINT64]
  4481  		}
  4482  		return t
  4483  	}
  4484  
  4485  	if callDef, ok := softFloatOps[op]; ok {
  4486  		switch op {
  4487  		case ssa.OpLess32F,
  4488  			ssa.OpLess64F,
  4489  			ssa.OpLeq32F,
  4490  			ssa.OpLeq64F:
  4491  			args[0], args[1] = args[1], args[0]
  4492  		case ssa.OpSub32F,
  4493  			ssa.OpSub64F:
  4494  			args[1] = s.newValue1(s.ssaOp(ir.ONEG, types.Types[callDef.rtype]), args[1].Type, args[1])
  4495  		}
  4496  
  4497  		// runtime functions take uints for floats and returns uints.
  4498  		// Convert to uints so we use the right calling convention.
  4499  		for i, a := range args {
  4500  			if a.Type.IsFloat() {
  4501  				args[i] = s.newValue1(ssa.OpCopy, f2i(a.Type), a)
  4502  			}
  4503  		}
  4504  
  4505  		rt := types.Types[callDef.rtype]
  4506  		result := s.rtcall(callDef.rtfn, true, []*types.Type{f2i(rt)}, args...)[0]
  4507  		if rt.IsFloat() {
  4508  			result = s.newValue1(ssa.OpCopy, rt, result)
  4509  		}
  4510  		if op == ssa.OpNeq32F || op == ssa.OpNeq64F {
  4511  			result = s.newValue1(ssa.OpNot, result.Type, result)
  4512  		}
  4513  		return result, true
  4514  	}
  4515  	return nil, false
  4516  }
  4517  
  4518  // split breaks up a tuple-typed value into its 2 parts.
  4519  func (s *state) split(v *ssa.Value) (*ssa.Value, *ssa.Value) {
  4520  	p0 := s.newValue1(ssa.OpSelect0, v.Type.FieldType(0), v)
  4521  	p1 := s.newValue1(ssa.OpSelect1, v.Type.FieldType(1), v)
  4522  	return p0, p1
  4523  }
  4524  
  4525  // intrinsicCall converts a call to a recognized intrinsic function into the intrinsic SSA operation.
  4526  func (s *state) intrinsicCall(n *ir.CallExpr) *ssa.Value {
  4527  	v := findIntrinsic(n.Fun.Sym())(s, n, s.intrinsicArgs(n))
  4528  	if ssa.IntrinsicsDebug > 0 {
  4529  		x := v
  4530  		if x == nil {
  4531  			x = s.mem()
  4532  		}
  4533  		if x.Op == ssa.OpSelect0 || x.Op == ssa.OpSelect1 {
  4534  			x = x.Args[0]
  4535  		}
  4536  		base.WarnfAt(n.Pos(), "intrinsic substitution for %v with %s", n.Fun.Sym().Name, x.LongString())
  4537  	}
  4538  	return v
  4539  }
  4540  
  4541  // intrinsicArgs extracts args from n, evaluates them to SSA values, and returns them.
  4542  func (s *state) intrinsicArgs(n *ir.CallExpr) []*ssa.Value {
  4543  	args := make([]*ssa.Value, len(n.Args))
  4544  	for i, n := range n.Args {
  4545  		args[i] = s.expr(n)
  4546  	}
  4547  	return args
  4548  }
  4549  
  4550  // openDeferRecord adds code to evaluate and store the function for an open-code defer
  4551  // call, and records info about the defer, so we can generate proper code on the
  4552  // exit paths. n is the sub-node of the defer node that is the actual function
  4553  // call. We will also record funcdata information on where the function is stored
  4554  // (as well as the deferBits variable), and this will enable us to run the proper
  4555  // defer calls during panics.
  4556  func (s *state) openDeferRecord(n *ir.CallExpr) {
  4557  	if len(n.Args) != 0 || n.Op() != ir.OCALLFUNC || n.Fun.Type().NumResults() != 0 {
  4558  		s.Fatalf("defer call with arguments or results: %v", n)
  4559  	}
  4560  
  4561  	opendefer := &openDeferInfo{
  4562  		n: n,
  4563  	}
  4564  	fn := n.Fun
  4565  	// We must always store the function value in a stack slot for the
  4566  	// runtime panic code to use. But in the defer exit code, we will
  4567  	// call the function directly if it is a static function.
  4568  	closureVal := s.expr(fn)
  4569  	closure := s.openDeferSave(fn.Type(), closureVal)
  4570  	opendefer.closureNode = closure.Aux.(*ir.Name)
  4571  	if !(fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC) {
  4572  		opendefer.closure = closure
  4573  	}
  4574  	index := len(s.openDefers)
  4575  	s.openDefers = append(s.openDefers, opendefer)
  4576  
  4577  	// Update deferBits only after evaluation and storage to stack of
  4578  	// the function is successful.
  4579  	bitvalue := s.constInt8(types.Types[types.TUINT8], 1<<uint(index))
  4580  	newDeferBits := s.newValue2(ssa.OpOr8, types.Types[types.TUINT8], s.variable(deferBitsVar, types.Types[types.TUINT8]), bitvalue)
  4581  	s.vars[deferBitsVar] = newDeferBits
  4582  	s.store(types.Types[types.TUINT8], s.deferBitsAddr, newDeferBits)
  4583  }
  4584  
  4585  // openDeferSave generates SSA nodes to store a value (with type t) for an
  4586  // open-coded defer at an explicit autotmp location on the stack, so it can be
  4587  // reloaded and used for the appropriate call on exit. Type t must be a function type
  4588  // (therefore SSAable). val is the value to be stored. The function returns an SSA
  4589  // value representing a pointer to the autotmp location.
  4590  func (s *state) openDeferSave(t *types.Type, val *ssa.Value) *ssa.Value {
  4591  	if !ssa.CanSSA(t) {
  4592  		s.Fatalf("openDeferSave of non-SSA-able type %v val=%v", t, val)
  4593  	}
  4594  	if !t.HasPointers() {
  4595  		s.Fatalf("openDeferSave of pointerless type %v val=%v", t, val)
  4596  	}
  4597  	pos := val.Pos
  4598  	temp := typecheck.TempAt(pos.WithNotStmt(), s.curfn, t)
  4599  	temp.SetOpenDeferSlot(true)
  4600  	temp.SetFrameOffset(int64(len(s.openDefers))) // so cmpstackvarlt can order them
  4601  	var addrTemp *ssa.Value
  4602  	// Use OpVarLive to make sure stack slot for the closure is not removed by
  4603  	// dead-store elimination
  4604  	if s.curBlock.ID != s.f.Entry.ID {
  4605  		// Force the tmp storing this defer function to be declared in the entry
  4606  		// block, so that it will be live for the defer exit code (which will
  4607  		// actually access it only if the associated defer call has been activated).
  4608  		if t.HasPointers() {
  4609  			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])
  4610  		}
  4611  		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])
  4612  		addrTemp = s.f.Entry.NewValue2A(src.NoXPos, ssa.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.defvars[s.f.Entry.ID][memVar])
  4613  	} else {
  4614  		// Special case if we're still in the entry block. We can't use
  4615  		// the above code, since s.defvars[s.f.Entry.ID] isn't defined
  4616  		// until we end the entry block with s.endBlock().
  4617  		if t.HasPointers() {
  4618  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, temp, s.mem(), false)
  4619  		}
  4620  		s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, temp, s.mem(), false)
  4621  		addrTemp = s.newValue2Apos(ssa.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.mem(), false)
  4622  	}
  4623  	// Since we may use this temp during exit depending on the
  4624  	// deferBits, we must define it unconditionally on entry.
  4625  	// Therefore, we must make sure it is zeroed out in the entry
  4626  	// block if it contains pointers, else GC may wrongly follow an
  4627  	// uninitialized pointer value.
  4628  	temp.SetNeedzero(true)
  4629  	// We are storing to the stack, hence we can avoid the full checks in
  4630  	// storeType() (no write barrier) and do a simple store().
  4631  	s.store(t, addrTemp, val)
  4632  	return addrTemp
  4633  }
  4634  
  4635  // openDeferExit generates SSA for processing all the open coded defers at exit.
  4636  // The code involves loading deferBits, and checking each of the bits to see if
  4637  // the corresponding defer statement was executed. For each bit that is turned
  4638  // on, the associated defer call is made.
  4639  func (s *state) openDeferExit() {
  4640  	deferExit := s.f.NewBlock(ssa.BlockPlain)
  4641  	s.endBlock().AddEdgeTo(deferExit)
  4642  	s.startBlock(deferExit)
  4643  	s.lastDeferExit = deferExit
  4644  	s.lastDeferCount = len(s.openDefers)
  4645  	zeroval := s.constInt8(types.Types[types.TUINT8], 0)
  4646  	// Test for and run defers in reverse order
  4647  	for i := len(s.openDefers) - 1; i >= 0; i-- {
  4648  		r := s.openDefers[i]
  4649  		bCond := s.f.NewBlock(ssa.BlockPlain)
  4650  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  4651  
  4652  		deferBits := s.variable(deferBitsVar, types.Types[types.TUINT8])
  4653  		// Generate code to check if the bit associated with the current
  4654  		// defer is set.
  4655  		bitval := s.constInt8(types.Types[types.TUINT8], 1<<uint(i))
  4656  		andval := s.newValue2(ssa.OpAnd8, types.Types[types.TUINT8], deferBits, bitval)
  4657  		eqVal := s.newValue2(ssa.OpEq8, types.Types[types.TBOOL], andval, zeroval)
  4658  		b := s.endBlock()
  4659  		b.Kind = ssa.BlockIf
  4660  		b.SetControl(eqVal)
  4661  		b.AddEdgeTo(bEnd)
  4662  		b.AddEdgeTo(bCond)
  4663  		bCond.AddEdgeTo(bEnd)
  4664  		s.startBlock(bCond)
  4665  
  4666  		// Clear this bit in deferBits and force store back to stack, so
  4667  		// we will not try to re-run this defer call if this defer call panics.
  4668  		nbitval := s.newValue1(ssa.OpCom8, types.Types[types.TUINT8], bitval)
  4669  		maskedval := s.newValue2(ssa.OpAnd8, types.Types[types.TUINT8], deferBits, nbitval)
  4670  		s.store(types.Types[types.TUINT8], s.deferBitsAddr, maskedval)
  4671  		// Use this value for following tests, so we keep previous
  4672  		// bits cleared.
  4673  		s.vars[deferBitsVar] = maskedval
  4674  
  4675  		// Generate code to call the function call of the defer, using the
  4676  		// closure that were stored in argtmps at the point of the defer
  4677  		// statement.
  4678  		fn := r.n.Fun
  4679  		stksize := fn.Type().ArgWidth()
  4680  		var callArgs []*ssa.Value
  4681  		var call *ssa.Value
  4682  		if r.closure != nil {
  4683  			v := s.load(r.closure.Type.Elem(), r.closure)
  4684  			s.maybeNilCheckClosure(v, callDefer)
  4685  			codeptr := s.rawLoad(types.Types[types.TUINTPTR], v)
  4686  			aux := ssa.ClosureAuxCall(s.f.ABIDefault.ABIAnalyzeTypes(nil, nil))
  4687  			call = s.newValue2A(ssa.OpClosureLECall, aux.LateExpansionResultType(), aux, codeptr, v)
  4688  		} else {
  4689  			aux := ssa.StaticAuxCall(fn.(*ir.Name).Linksym(), s.f.ABIDefault.ABIAnalyzeTypes(nil, nil))
  4690  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4691  		}
  4692  		callArgs = append(callArgs, s.mem())
  4693  		call.AddArgs(callArgs...)
  4694  		call.AuxInt = stksize
  4695  		s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, 0, call)
  4696  		// Make sure that the stack slots with pointers are kept live
  4697  		// through the call (which is a pre-emption point). Also, we will
  4698  		// use the first call of the last defer exit to compute liveness
  4699  		// for the deferreturn, so we want all stack slots to be live.
  4700  		if r.closureNode != nil {
  4701  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, r.closureNode, s.mem(), false)
  4702  		}
  4703  
  4704  		s.endBlock()
  4705  		s.startBlock(bEnd)
  4706  	}
  4707  }
  4708  
  4709  func (s *state) callResult(n *ir.CallExpr, k callKind) *ssa.Value {
  4710  	return s.call(n, k, false, nil)
  4711  }
  4712  
  4713  func (s *state) callAddr(n *ir.CallExpr, k callKind) *ssa.Value {
  4714  	return s.call(n, k, true, nil)
  4715  }
  4716  
  4717  // Calls the function n using the specified call type.
  4718  // Returns the address of the return value (or nil if none).
  4719  func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool, deferExtra ir.Expr) *ssa.Value {
  4720  	s.prevCall = nil
  4721  	var calleeLSym *obj.LSym // target function (if static)
  4722  	var closure *ssa.Value   // ptr to closure to run (if dynamic)
  4723  	var codeptr *ssa.Value   // ptr to target code (if dynamic)
  4724  	var dextra *ssa.Value    // defer extra arg
  4725  	var rcvr *ssa.Value      // receiver to set
  4726  	fn := n.Fun
  4727  	var ACArgs []*types.Type    // AuxCall args
  4728  	var ACResults []*types.Type // AuxCall results
  4729  	var callArgs []*ssa.Value   // For late-expansion, the args themselves (not stored, args to the call instead).
  4730  
  4731  	callABI := s.f.ABIDefault
  4732  
  4733  	if k != callNormal && k != callTail && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.Fun.Type().NumResults() != 0) {
  4734  		s.Fatalf("go/defer call with arguments: %v", n)
  4735  	}
  4736  
  4737  	isCallDeferRangeFunc := false
  4738  
  4739  	switch n.Op() {
  4740  	case ir.OCALLFUNC:
  4741  		if (k == callNormal || k == callTail) && fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC {
  4742  			fn := fn.(*ir.Name)
  4743  			calleeLSym = callTargetLSym(fn)
  4744  			if buildcfg.Experiment.RegabiArgs {
  4745  				// This is a static call, so it may be
  4746  				// a direct call to a non-ABIInternal
  4747  				// function. fn.Func may be nil for
  4748  				// some compiler-generated functions,
  4749  				// but those are all ABIInternal.
  4750  				if fn.Func != nil {
  4751  					callABI = abiForFunc(fn.Func, s.f.ABI0, s.f.ABI1)
  4752  				}
  4753  			} else {
  4754  				// TODO(register args) remove after register abi is working
  4755  				inRegistersImported := fn.Pragma()&ir.RegisterParams != 0
  4756  				inRegistersSamePackage := fn.Func != nil && fn.Func.Pragma&ir.RegisterParams != 0
  4757  				if inRegistersImported || inRegistersSamePackage {
  4758  					callABI = s.f.ABI1
  4759  				}
  4760  			}
  4761  			if fn := n.Fun.Sym().Name; n.Fun.Sym().Pkg == ir.Pkgs.Runtime && fn == "deferrangefunc" {
  4762  				isCallDeferRangeFunc = true
  4763  			}
  4764  			break
  4765  		}
  4766  		closure = s.expr(fn)
  4767  		if k != callDefer && k != callDeferStack {
  4768  			// Deferred nil function needs to panic when the function is invoked,
  4769  			// not the point of defer statement.
  4770  			s.maybeNilCheckClosure(closure, k)
  4771  		}
  4772  	case ir.OCALLINTER:
  4773  		if fn.Op() != ir.ODOTINTER {
  4774  			s.Fatalf("OCALLINTER: n.Left not an ODOTINTER: %v", fn.Op())
  4775  		}
  4776  		fn := fn.(*ir.SelectorExpr)
  4777  		var iclosure *ssa.Value
  4778  		iclosure, rcvr = s.getClosureAndRcvr(fn)
  4779  		if k == callNormal {
  4780  			codeptr = s.load(types.Types[types.TUINTPTR], iclosure)
  4781  		} else {
  4782  			closure = iclosure
  4783  		}
  4784  	}
  4785  	if deferExtra != nil {
  4786  		dextra = s.expr(deferExtra)
  4787  	}
  4788  
  4789  	params := callABI.ABIAnalyze(n.Fun.Type(), false /* Do not set (register) nNames from caller side -- can cause races. */)
  4790  	types.CalcSize(fn.Type())
  4791  	stksize := params.ArgWidth() // includes receiver, args, and results
  4792  
  4793  	res := n.Fun.Type().Results()
  4794  	if k == callNormal || k == callTail {
  4795  		for _, p := range params.OutParams() {
  4796  			ACResults = append(ACResults, p.Type)
  4797  		}
  4798  	}
  4799  
  4800  	var call *ssa.Value
  4801  	if k == callDeferStack {
  4802  		if stksize != 0 {
  4803  			s.Fatalf("deferprocStack with non-zero stack size %d: %v", stksize, n)
  4804  		}
  4805  		// Make a defer struct on the stack.
  4806  		t := deferstruct()
  4807  		n, addr := s.temp(n.Pos(), t)
  4808  		n.SetNonMergeable(true)
  4809  		s.store(closure.Type,
  4810  			s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(deferStructFnField), addr),
  4811  			closure)
  4812  
  4813  		// Call runtime.deferprocStack with pointer to _defer record.
  4814  		ACArgs = append(ACArgs, types.Types[types.TUINTPTR])
  4815  		aux := ssa.StaticAuxCall(ir.Syms.DeferprocStack, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults))
  4816  		callArgs = append(callArgs, addr, s.mem())
  4817  		call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4818  		call.AddArgs(callArgs...)
  4819  		call.AuxInt = int64(types.PtrSize) // deferprocStack takes a *_defer arg
  4820  	} else {
  4821  		// Store arguments to stack, including defer/go arguments and receiver for method calls.
  4822  		// These are written in SP-offset order.
  4823  		argStart := base.Ctxt.Arch.FixedFrameSize
  4824  		// Defer/go args.
  4825  		if k != callNormal && k != callTail {
  4826  			// Write closure (arg to newproc/deferproc).
  4827  			ACArgs = append(ACArgs, types.Types[types.TUINTPTR]) // not argExtra
  4828  			callArgs = append(callArgs, closure)
  4829  			stksize += int64(types.PtrSize)
  4830  			argStart += int64(types.PtrSize)
  4831  			if dextra != nil {
  4832  				// Extra token of type any for deferproc
  4833  				ACArgs = append(ACArgs, types.Types[types.TINTER])
  4834  				callArgs = append(callArgs, dextra)
  4835  				stksize += 2 * int64(types.PtrSize)
  4836  				argStart += 2 * int64(types.PtrSize)
  4837  			}
  4838  		}
  4839  
  4840  		// Set receiver (for interface calls).
  4841  		if rcvr != nil {
  4842  			callArgs = append(callArgs, rcvr)
  4843  		}
  4844  
  4845  		// Write args.
  4846  		t := n.Fun.Type()
  4847  		args := n.Args
  4848  
  4849  		for _, p := range params.InParams() { // includes receiver for interface calls
  4850  			ACArgs = append(ACArgs, p.Type)
  4851  		}
  4852  
  4853  		// Split the entry block if there are open defers, because later calls to
  4854  		// openDeferSave may cause a mismatch between the mem for an OpDereference
  4855  		// and the call site which uses it. See #49282.
  4856  		if s.curBlock.ID == s.f.Entry.ID && s.hasOpenDefers {
  4857  			b := s.endBlock()
  4858  			b.Kind = ssa.BlockPlain
  4859  			curb := s.f.NewBlock(ssa.BlockPlain)
  4860  			b.AddEdgeTo(curb)
  4861  			s.startBlock(curb)
  4862  		}
  4863  
  4864  		for i, n := range args {
  4865  			callArgs = append(callArgs, s.putArg(n, t.Param(i).Type))
  4866  		}
  4867  
  4868  		callArgs = append(callArgs, s.mem())
  4869  
  4870  		// call target
  4871  		switch {
  4872  		case k == callDefer:
  4873  			sym := ir.Syms.Deferproc
  4874  			if dextra != nil {
  4875  				sym = ir.Syms.Deferprocat
  4876  			}
  4877  			aux := ssa.StaticAuxCall(sym, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults)) // TODO paramResultInfo for Deferproc(at)
  4878  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4879  		case k == callGo:
  4880  			aux := ssa.StaticAuxCall(ir.Syms.Newproc, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults))
  4881  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux) // TODO paramResultInfo for Newproc
  4882  		case closure != nil:
  4883  			// rawLoad because loading the code pointer from a
  4884  			// closure is always safe, but IsSanitizerSafeAddr
  4885  			// can't always figure that out currently, and it's
  4886  			// critical that we not clobber any arguments already
  4887  			// stored onto the stack.
  4888  			codeptr = s.rawLoad(types.Types[types.TUINTPTR], closure)
  4889  			aux := ssa.ClosureAuxCall(callABI.ABIAnalyzeTypes(ACArgs, ACResults))
  4890  			call = s.newValue2A(ssa.OpClosureLECall, aux.LateExpansionResultType(), aux, codeptr, closure)
  4891  		case codeptr != nil:
  4892  			// Note that the "receiver" parameter is nil because the actual receiver is the first input parameter.
  4893  			aux := ssa.InterfaceAuxCall(params)
  4894  			call = s.newValue1A(ssa.OpInterLECall, aux.LateExpansionResultType(), aux, codeptr)
  4895  		case calleeLSym != nil:
  4896  			aux := ssa.StaticAuxCall(calleeLSym, params)
  4897  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4898  			if k == callTail {
  4899  				call.Op = ssa.OpTailLECall
  4900  				stksize = 0 // Tail call does not use stack. We reuse caller's frame.
  4901  			}
  4902  		default:
  4903  			s.Fatalf("bad call type %v %v", n.Op(), n)
  4904  		}
  4905  		call.AddArgs(callArgs...)
  4906  		call.AuxInt = stksize // Call operations carry the argsize of the callee along with them
  4907  	}
  4908  	s.prevCall = call
  4909  	s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, int64(len(ACResults)), call)
  4910  	// Insert VarLive opcodes.
  4911  	for _, v := range n.KeepAlive {
  4912  		if !v.Addrtaken() {
  4913  			s.Fatalf("KeepAlive variable %v must have Addrtaken set", v)
  4914  		}
  4915  		switch v.Class {
  4916  		case ir.PAUTO, ir.PPARAM, ir.PPARAMOUT:
  4917  		default:
  4918  			s.Fatalf("KeepAlive variable %v must be Auto or Arg", v)
  4919  		}
  4920  		s.vars[memVar] = s.newValue1A(ssa.OpVarLive, types.TypeMem, v, s.mem())
  4921  	}
  4922  
  4923  	// Finish block for defers
  4924  	if k == callDefer || k == callDeferStack || isCallDeferRangeFunc {
  4925  		b := s.endBlock()
  4926  		b.Kind = ssa.BlockDefer
  4927  		b.SetControl(call)
  4928  		bNext := s.f.NewBlock(ssa.BlockPlain)
  4929  		b.AddEdgeTo(bNext)
  4930  		r := s.f.DeferReturn // Share a single deferreturn among all defers
  4931  		if r == nil {
  4932  			r = s.f.NewBlock(ssa.BlockPlain)
  4933  			s.startBlock(r)
  4934  			s.exit()
  4935  			s.f.DeferReturn = r
  4936  		}
  4937  		b.AddEdgeTo(r) // Add recover edge to exit code.  This is a fake edge to keep the block live.
  4938  		b.Likely = ssa.BranchLikely
  4939  		s.startBlock(bNext)
  4940  	}
  4941  
  4942  	if len(res) == 0 || k != callNormal {
  4943  		// call has no return value. Continue with the next statement.
  4944  		return nil
  4945  	}
  4946  	fp := res[0]
  4947  	if returnResultAddr {
  4948  		return s.resultAddrOfCall(call, 0, fp.Type)
  4949  	}
  4950  	return s.newValue1I(ssa.OpSelectN, fp.Type, 0, call)
  4951  }
  4952  
  4953  // maybeNilCheckClosure checks if a nil check of a closure is needed in some
  4954  // architecture-dependent situations and, if so, emits the nil check.
  4955  func (s *state) maybeNilCheckClosure(closure *ssa.Value, k callKind) {
  4956  	if Arch.LinkArch.Family == sys.Wasm || buildcfg.GOOS == "aix" && k != callGo {
  4957  		// 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.
  4958  		// TODO(neelance): On other architectures this should be eliminated by the optimization steps
  4959  		s.nilCheck(closure)
  4960  	}
  4961  }
  4962  
  4963  // getClosureAndRcvr returns values for the appropriate closure and receiver of an
  4964  // interface call
  4965  func (s *state) getClosureAndRcvr(fn *ir.SelectorExpr) (*ssa.Value, *ssa.Value) {
  4966  	i := s.expr(fn.X)
  4967  	itab := s.newValue1(ssa.OpITab, types.Types[types.TUINTPTR], i)
  4968  	s.nilCheck(itab)
  4969  	itabidx := fn.Offset() + rttype.ITab.OffsetOf("Fun")
  4970  	closure := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.UintptrPtr, itabidx, itab)
  4971  	rcvr := s.newValue1(ssa.OpIData, s.f.Config.Types.BytePtr, i)
  4972  	return closure, rcvr
  4973  }
  4974  
  4975  // etypesign returns the signed-ness of e, for integer/pointer etypes.
  4976  // -1 means signed, +1 means unsigned, 0 means non-integer/non-pointer.
  4977  func etypesign(e types.Kind) int8 {
  4978  	switch e {
  4979  	case types.TINT8, types.TINT16, types.TINT32, types.TINT64, types.TINT:
  4980  		return -1
  4981  	case types.TUINT8, types.TUINT16, types.TUINT32, types.TUINT64, types.TUINT, types.TUINTPTR, types.TUNSAFEPTR:
  4982  		return +1
  4983  	}
  4984  	return 0
  4985  }
  4986  
  4987  // addr converts the address of the expression n to SSA, adds it to s and returns the SSA result.
  4988  // The value that the returned Value represents is guaranteed to be non-nil.
  4989  func (s *state) addr(n ir.Node) *ssa.Value {
  4990  	if n.Op() != ir.ONAME {
  4991  		s.pushLine(n.Pos())
  4992  		defer s.popLine()
  4993  	}
  4994  
  4995  	if s.canSSA(n) {
  4996  		s.Fatalf("addr of canSSA expression: %+v", n)
  4997  	}
  4998  
  4999  	t := types.NewPtr(n.Type())
  5000  	linksymOffset := func(lsym *obj.LSym, offset int64) *ssa.Value {
  5001  		v := s.entryNewValue1A(ssa.OpAddr, t, lsym, s.sb)
  5002  		// TODO: Make OpAddr use AuxInt as well as Aux.
  5003  		if offset != 0 {
  5004  			v = s.entryNewValue1I(ssa.OpOffPtr, v.Type, offset, v)
  5005  		}
  5006  		return v
  5007  	}
  5008  	switch n.Op() {
  5009  	case ir.OLINKSYMOFFSET:
  5010  		no := n.(*ir.LinksymOffsetExpr)
  5011  		return linksymOffset(no.Linksym, no.Offset_)
  5012  	case ir.ONAME:
  5013  		n := n.(*ir.Name)
  5014  		if n.Heapaddr != nil {
  5015  			return s.expr(n.Heapaddr)
  5016  		}
  5017  		switch n.Class {
  5018  		case ir.PEXTERN:
  5019  			// global variable
  5020  			return linksymOffset(n.Linksym(), 0)
  5021  		case ir.PPARAM:
  5022  			// parameter slot
  5023  			v := s.decladdrs[n]
  5024  			if v != nil {
  5025  				return v
  5026  			}
  5027  			s.Fatalf("addr of undeclared ONAME %v. declared: %v", n, s.decladdrs)
  5028  			return nil
  5029  		case ir.PAUTO:
  5030  			return s.newValue2Apos(ssa.OpLocalAddr, t, n, s.sp, s.mem(), !ir.IsAutoTmp(n))
  5031  
  5032  		case ir.PPARAMOUT: // Same as PAUTO -- cannot generate LEA early.
  5033  			// ensure that we reuse symbols for out parameters so
  5034  			// that cse works on their addresses
  5035  			return s.newValue2Apos(ssa.OpLocalAddr, t, n, s.sp, s.mem(), true)
  5036  		default:
  5037  			s.Fatalf("variable address class %v not implemented", n.Class)
  5038  			return nil
  5039  		}
  5040  	case ir.ORESULT:
  5041  		// load return from callee
  5042  		n := n.(*ir.ResultExpr)
  5043  		return s.resultAddrOfCall(s.prevCall, n.Index, n.Type())
  5044  	case ir.OINDEX:
  5045  		n := n.(*ir.IndexExpr)
  5046  		if n.X.Type().IsSlice() {
  5047  			a := s.expr(n.X)
  5048  			i := s.expr(n.Index)
  5049  			len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], a)
  5050  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  5051  			p := s.newValue1(ssa.OpSlicePtr, t, a)
  5052  			return s.newValue2(ssa.OpPtrIndex, t, p, i)
  5053  		} else { // array
  5054  			a := s.addr(n.X)
  5055  			i := s.expr(n.Index)
  5056  			len := s.constInt(types.Types[types.TINT], n.X.Type().NumElem())
  5057  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  5058  			return s.newValue2(ssa.OpPtrIndex, types.NewPtr(n.X.Type().Elem()), a, i)
  5059  		}
  5060  	case ir.ODEREF:
  5061  		n := n.(*ir.StarExpr)
  5062  		return s.exprPtr(n.X, n.Bounded(), n.Pos())
  5063  	case ir.ODOT:
  5064  		n := n.(*ir.SelectorExpr)
  5065  		p := s.addr(n.X)
  5066  		return s.newValue1I(ssa.OpOffPtr, t, n.Offset(), p)
  5067  	case ir.ODOTPTR:
  5068  		n := n.(*ir.SelectorExpr)
  5069  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  5070  		return s.newValue1I(ssa.OpOffPtr, t, n.Offset(), p)
  5071  	case ir.OCONVNOP:
  5072  		n := n.(*ir.ConvExpr)
  5073  		if n.Type() == n.X.Type() {
  5074  			return s.addr(n.X)
  5075  		}
  5076  		addr := s.addr(n.X)
  5077  		return s.newValue1(ssa.OpCopy, t, addr) // ensure that addr has the right type
  5078  	case ir.OCALLFUNC, ir.OCALLINTER:
  5079  		n := n.(*ir.CallExpr)
  5080  		return s.callAddr(n, callNormal)
  5081  	case ir.ODOTTYPE, ir.ODYNAMICDOTTYPE:
  5082  		var v *ssa.Value
  5083  		if n.Op() == ir.ODOTTYPE {
  5084  			v, _ = s.dottype(n.(*ir.TypeAssertExpr), false)
  5085  		} else {
  5086  			v, _ = s.dynamicDottype(n.(*ir.DynamicTypeAssertExpr), false)
  5087  		}
  5088  		if v.Op != ssa.OpLoad {
  5089  			s.Fatalf("dottype of non-load")
  5090  		}
  5091  		if v.Args[1] != s.mem() {
  5092  			s.Fatalf("memory no longer live from dottype load")
  5093  		}
  5094  		return v.Args[0]
  5095  	default:
  5096  		s.Fatalf("unhandled addr %v", n.Op())
  5097  		return nil
  5098  	}
  5099  }
  5100  
  5101  // canSSA reports whether n is SSA-able.
  5102  // n must be an ONAME (or an ODOT sequence with an ONAME base).
  5103  func (s *state) canSSA(n ir.Node) bool {
  5104  	if base.Flag.N != 0 {
  5105  		return false
  5106  	}
  5107  	for {
  5108  		nn := n
  5109  		if nn.Op() == ir.ODOT {
  5110  			nn := nn.(*ir.SelectorExpr)
  5111  			n = nn.X
  5112  			continue
  5113  		}
  5114  		if nn.Op() == ir.OINDEX {
  5115  			nn := nn.(*ir.IndexExpr)
  5116  			if nn.X.Type().IsArray() {
  5117  				n = nn.X
  5118  				continue
  5119  			}
  5120  		}
  5121  		break
  5122  	}
  5123  	if n.Op() != ir.ONAME {
  5124  		return false
  5125  	}
  5126  	return s.canSSAName(n.(*ir.Name)) && ssa.CanSSA(n.Type())
  5127  }
  5128  
  5129  func (s *state) canSSAName(name *ir.Name) bool {
  5130  	if name.Addrtaken() || !name.OnStack() {
  5131  		return false
  5132  	}
  5133  	switch name.Class {
  5134  	case ir.PPARAMOUT:
  5135  		if s.hasdefer {
  5136  			// TODO: handle this case? Named return values must be
  5137  			// in memory so that the deferred function can see them.
  5138  			// Maybe do: if !strings.HasPrefix(n.String(), "~") { return false }
  5139  			// Or maybe not, see issue 18860.  Even unnamed return values
  5140  			// must be written back so if a defer recovers, the caller can see them.
  5141  			return false
  5142  		}
  5143  		if s.cgoUnsafeArgs {
  5144  			// Cgo effectively takes the address of all result args,
  5145  			// but the compiler can't see that.
  5146  			return false
  5147  		}
  5148  	}
  5149  	return true
  5150  	// TODO: try to make more variables SSAable?
  5151  }
  5152  
  5153  // exprPtr evaluates n to a pointer and nil-checks it.
  5154  func (s *state) exprPtr(n ir.Node, bounded bool, lineno src.XPos) *ssa.Value {
  5155  	p := s.expr(n)
  5156  	if bounded || n.NonNil() {
  5157  		if s.f.Frontend().Debug_checknil() && lineno.Line() > 1 {
  5158  			s.f.Warnl(lineno, "removed nil check")
  5159  		}
  5160  		return p
  5161  	}
  5162  	p = s.nilCheck(p)
  5163  	return p
  5164  }
  5165  
  5166  // nilCheck generates nil pointer checking code.
  5167  // Used only for automatically inserted nil checks,
  5168  // not for user code like 'x != nil'.
  5169  // Returns a "definitely not nil" copy of x to ensure proper ordering
  5170  // of the uses of the post-nilcheck pointer.
  5171  func (s *state) nilCheck(ptr *ssa.Value) *ssa.Value {
  5172  	if base.Debug.DisableNil != 0 || s.curfn.NilCheckDisabled() {
  5173  		return ptr
  5174  	}
  5175  	return s.newValue2(ssa.OpNilCheck, ptr.Type, ptr, s.mem())
  5176  }
  5177  
  5178  // boundsCheck generates bounds checking code. Checks if 0 <= idx <[=] len, branches to exit if not.
  5179  // Starts a new block on return.
  5180  // On input, len must be converted to full int width and be nonnegative.
  5181  // Returns idx converted to full int width.
  5182  // If bounded is true then caller guarantees the index is not out of bounds
  5183  // (but boundsCheck will still extend the index to full int width).
  5184  func (s *state) boundsCheck(idx, len *ssa.Value, kind ssa.BoundsKind, bounded bool) *ssa.Value {
  5185  	idx = s.extendIndex(idx, len, kind, bounded)
  5186  
  5187  	if bounded || base.Flag.B != 0 {
  5188  		// If bounded or bounds checking is flag-disabled, then no check necessary,
  5189  		// just return the extended index.
  5190  		//
  5191  		// Here, bounded == true if the compiler generated the index itself,
  5192  		// such as in the expansion of a slice initializer. These indexes are
  5193  		// compiler-generated, not Go program variables, so they cannot be
  5194  		// attacker-controlled, so we can omit Spectre masking as well.
  5195  		//
  5196  		// Note that we do not want to omit Spectre masking in code like:
  5197  		//
  5198  		//	if 0 <= i && i < len(x) {
  5199  		//		use(x[i])
  5200  		//	}
  5201  		//
  5202  		// Lucky for us, bounded==false for that code.
  5203  		// In that case (handled below), we emit a bound check (and Spectre mask)
  5204  		// and then the prove pass will remove the bounds check.
  5205  		// In theory the prove pass could potentially remove certain
  5206  		// Spectre masks, but it's very delicate and probably better
  5207  		// to be conservative and leave them all in.
  5208  		return idx
  5209  	}
  5210  
  5211  	bNext := s.f.NewBlock(ssa.BlockPlain)
  5212  	bPanic := s.f.NewBlock(ssa.BlockExit)
  5213  
  5214  	if !idx.Type.IsSigned() {
  5215  		switch kind {
  5216  		case ssa.BoundsIndex:
  5217  			kind = ssa.BoundsIndexU
  5218  		case ssa.BoundsSliceAlen:
  5219  			kind = ssa.BoundsSliceAlenU
  5220  		case ssa.BoundsSliceAcap:
  5221  			kind = ssa.BoundsSliceAcapU
  5222  		case ssa.BoundsSliceB:
  5223  			kind = ssa.BoundsSliceBU
  5224  		case ssa.BoundsSlice3Alen:
  5225  			kind = ssa.BoundsSlice3AlenU
  5226  		case ssa.BoundsSlice3Acap:
  5227  			kind = ssa.BoundsSlice3AcapU
  5228  		case ssa.BoundsSlice3B:
  5229  			kind = ssa.BoundsSlice3BU
  5230  		case ssa.BoundsSlice3C:
  5231  			kind = ssa.BoundsSlice3CU
  5232  		}
  5233  	}
  5234  
  5235  	var cmp *ssa.Value
  5236  	if kind == ssa.BoundsIndex || kind == ssa.BoundsIndexU {
  5237  		cmp = s.newValue2(ssa.OpIsInBounds, types.Types[types.TBOOL], idx, len)
  5238  	} else {
  5239  		cmp = s.newValue2(ssa.OpIsSliceInBounds, types.Types[types.TBOOL], idx, len)
  5240  	}
  5241  	b := s.endBlock()
  5242  	b.Kind = ssa.BlockIf
  5243  	b.SetControl(cmp)
  5244  	b.Likely = ssa.BranchLikely
  5245  	b.AddEdgeTo(bNext)
  5246  	b.AddEdgeTo(bPanic)
  5247  
  5248  	s.startBlock(bPanic)
  5249  	if Arch.LinkArch.Family == sys.Wasm {
  5250  		// TODO(khr): figure out how to do "register" based calling convention for bounds checks.
  5251  		// Should be similar to gcWriteBarrier, but I can't make it work.
  5252  		s.rtcall(BoundsCheckFunc[kind], false, nil, idx, len)
  5253  	} else {
  5254  		mem := s.newValue3I(ssa.OpPanicBounds, types.TypeMem, int64(kind), idx, len, s.mem())
  5255  		s.endBlock().SetControl(mem)
  5256  	}
  5257  	s.startBlock(bNext)
  5258  
  5259  	// In Spectre index mode, apply an appropriate mask to avoid speculative out-of-bounds accesses.
  5260  	if base.Flag.Cfg.SpectreIndex {
  5261  		op := ssa.OpSpectreIndex
  5262  		if kind != ssa.BoundsIndex && kind != ssa.BoundsIndexU {
  5263  			op = ssa.OpSpectreSliceIndex
  5264  		}
  5265  		idx = s.newValue2(op, types.Types[types.TINT], idx, len)
  5266  	}
  5267  
  5268  	return idx
  5269  }
  5270  
  5271  // If cmp (a bool) is false, panic using the given function.
  5272  func (s *state) check(cmp *ssa.Value, fn *obj.LSym) {
  5273  	b := s.endBlock()
  5274  	b.Kind = ssa.BlockIf
  5275  	b.SetControl(cmp)
  5276  	b.Likely = ssa.BranchLikely
  5277  	bNext := s.f.NewBlock(ssa.BlockPlain)
  5278  	line := s.peekPos()
  5279  	pos := base.Ctxt.PosTable.Pos(line)
  5280  	fl := funcLine{f: fn, base: pos.Base(), line: pos.Line()}
  5281  	bPanic := s.panics[fl]
  5282  	if bPanic == nil {
  5283  		bPanic = s.f.NewBlock(ssa.BlockPlain)
  5284  		s.panics[fl] = bPanic
  5285  		s.startBlock(bPanic)
  5286  		// The panic call takes/returns memory to ensure that the right
  5287  		// memory state is observed if the panic happens.
  5288  		s.rtcall(fn, false, nil)
  5289  	}
  5290  	b.AddEdgeTo(bNext)
  5291  	b.AddEdgeTo(bPanic)
  5292  	s.startBlock(bNext)
  5293  }
  5294  
  5295  func (s *state) intDivide(n ir.Node, a, b *ssa.Value) *ssa.Value {
  5296  	needcheck := true
  5297  	switch b.Op {
  5298  	case ssa.OpConst8, ssa.OpConst16, ssa.OpConst32, ssa.OpConst64:
  5299  		if b.AuxInt != 0 {
  5300  			needcheck = false
  5301  		}
  5302  	}
  5303  	if needcheck {
  5304  		// do a size-appropriate check for zero
  5305  		cmp := s.newValue2(s.ssaOp(ir.ONE, n.Type()), types.Types[types.TBOOL], b, s.zeroVal(n.Type()))
  5306  		s.check(cmp, ir.Syms.Panicdivide)
  5307  	}
  5308  	return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  5309  }
  5310  
  5311  // rtcall issues a call to the given runtime function fn with the listed args.
  5312  // Returns a slice of results of the given result types.
  5313  // The call is added to the end of the current block.
  5314  // If returns is false, the block is marked as an exit block.
  5315  func (s *state) rtcall(fn *obj.LSym, returns bool, results []*types.Type, args ...*ssa.Value) []*ssa.Value {
  5316  	s.prevCall = nil
  5317  	// Write args to the stack
  5318  	off := base.Ctxt.Arch.FixedFrameSize
  5319  	var callArgs []*ssa.Value
  5320  	var callArgTypes []*types.Type
  5321  
  5322  	for _, arg := range args {
  5323  		t := arg.Type
  5324  		off = types.RoundUp(off, t.Alignment())
  5325  		size := t.Size()
  5326  		callArgs = append(callArgs, arg)
  5327  		callArgTypes = append(callArgTypes, t)
  5328  		off += size
  5329  	}
  5330  	off = types.RoundUp(off, int64(types.RegSize))
  5331  
  5332  	// Issue call
  5333  	var call *ssa.Value
  5334  	aux := ssa.StaticAuxCall(fn, s.f.ABIDefault.ABIAnalyzeTypes(callArgTypes, results))
  5335  	callArgs = append(callArgs, s.mem())
  5336  	call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  5337  	call.AddArgs(callArgs...)
  5338  	s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, int64(len(results)), call)
  5339  
  5340  	if !returns {
  5341  		// Finish block
  5342  		b := s.endBlock()
  5343  		b.Kind = ssa.BlockExit
  5344  		b.SetControl(call)
  5345  		call.AuxInt = off - base.Ctxt.Arch.FixedFrameSize
  5346  		if len(results) > 0 {
  5347  			s.Fatalf("panic call can't have results")
  5348  		}
  5349  		return nil
  5350  	}
  5351  
  5352  	// Load results
  5353  	res := make([]*ssa.Value, len(results))
  5354  	for i, t := range results {
  5355  		off = types.RoundUp(off, t.Alignment())
  5356  		res[i] = s.resultOfCall(call, int64(i), t)
  5357  		off += t.Size()
  5358  	}
  5359  	off = types.RoundUp(off, int64(types.PtrSize))
  5360  
  5361  	// Remember how much callee stack space we needed.
  5362  	call.AuxInt = off
  5363  
  5364  	return res
  5365  }
  5366  
  5367  // do *left = right for type t.
  5368  func (s *state) storeType(t *types.Type, left, right *ssa.Value, skip skipMask, leftIsStmt bool) {
  5369  	s.instrument(t, left, instrumentWrite)
  5370  
  5371  	if skip == 0 && (!t.HasPointers() || ssa.IsStackAddr(left)) {
  5372  		// Known to not have write barrier. Store the whole type.
  5373  		s.vars[memVar] = s.newValue3Apos(ssa.OpStore, types.TypeMem, t, left, right, s.mem(), leftIsStmt)
  5374  		return
  5375  	}
  5376  
  5377  	// store scalar fields first, so write barrier stores for
  5378  	// pointer fields can be grouped together, and scalar values
  5379  	// don't need to be live across the write barrier call.
  5380  	// TODO: if the writebarrier pass knows how to reorder stores,
  5381  	// we can do a single store here as long as skip==0.
  5382  	s.storeTypeScalars(t, left, right, skip)
  5383  	if skip&skipPtr == 0 && t.HasPointers() {
  5384  		s.storeTypePtrs(t, left, right)
  5385  	}
  5386  }
  5387  
  5388  // do *left = right for all scalar (non-pointer) parts of t.
  5389  func (s *state) storeTypeScalars(t *types.Type, left, right *ssa.Value, skip skipMask) {
  5390  	switch {
  5391  	case t.IsBoolean() || t.IsInteger() || t.IsFloat() || t.IsComplex():
  5392  		s.store(t, left, right)
  5393  	case t.IsPtrShaped():
  5394  		if t.IsPtr() && t.Elem().NotInHeap() {
  5395  			s.store(t, left, right) // see issue 42032
  5396  		}
  5397  		// otherwise, no scalar fields.
  5398  	case t.IsString():
  5399  		if skip&skipLen != 0 {
  5400  			return
  5401  		}
  5402  		len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], right)
  5403  		lenAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, s.config.PtrSize, left)
  5404  		s.store(types.Types[types.TINT], lenAddr, len)
  5405  	case t.IsSlice():
  5406  		if skip&skipLen == 0 {
  5407  			len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], right)
  5408  			lenAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, s.config.PtrSize, left)
  5409  			s.store(types.Types[types.TINT], lenAddr, len)
  5410  		}
  5411  		if skip&skipCap == 0 {
  5412  			cap := s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], right)
  5413  			capAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, 2*s.config.PtrSize, left)
  5414  			s.store(types.Types[types.TINT], capAddr, cap)
  5415  		}
  5416  	case t.IsInterface():
  5417  		// itab field doesn't need a write barrier (even though it is a pointer).
  5418  		itab := s.newValue1(ssa.OpITab, s.f.Config.Types.BytePtr, right)
  5419  		s.store(types.Types[types.TUINTPTR], left, itab)
  5420  	case t.IsStruct():
  5421  		n := t.NumFields()
  5422  		for i := 0; i < n; i++ {
  5423  			ft := t.FieldType(i)
  5424  			addr := s.newValue1I(ssa.OpOffPtr, ft.PtrTo(), t.FieldOff(i), left)
  5425  			val := s.newValue1I(ssa.OpStructSelect, ft, int64(i), right)
  5426  			s.storeTypeScalars(ft, addr, val, 0)
  5427  		}
  5428  	case t.IsArray() && t.NumElem() == 0:
  5429  		// nothing
  5430  	case t.IsArray() && t.NumElem() == 1:
  5431  		s.storeTypeScalars(t.Elem(), left, s.newValue1I(ssa.OpArraySelect, t.Elem(), 0, right), 0)
  5432  	default:
  5433  		s.Fatalf("bad write barrier type %v", t)
  5434  	}
  5435  }
  5436  
  5437  // do *left = right for all pointer parts of t.
  5438  func (s *state) storeTypePtrs(t *types.Type, left, right *ssa.Value) {
  5439  	switch {
  5440  	case t.IsPtrShaped():
  5441  		if t.IsPtr() && t.Elem().NotInHeap() {
  5442  			break // see issue 42032
  5443  		}
  5444  		s.store(t, left, right)
  5445  	case t.IsString():
  5446  		ptr := s.newValue1(ssa.OpStringPtr, s.f.Config.Types.BytePtr, right)
  5447  		s.store(s.f.Config.Types.BytePtr, left, ptr)
  5448  	case t.IsSlice():
  5449  		elType := types.NewPtr(t.Elem())
  5450  		ptr := s.newValue1(ssa.OpSlicePtr, elType, right)
  5451  		s.store(elType, left, ptr)
  5452  	case t.IsInterface():
  5453  		// itab field is treated as a scalar.
  5454  		idata := s.newValue1(ssa.OpIData, s.f.Config.Types.BytePtr, right)
  5455  		idataAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.BytePtrPtr, s.config.PtrSize, left)
  5456  		s.store(s.f.Config.Types.BytePtr, idataAddr, idata)
  5457  	case t.IsStruct():
  5458  		n := t.NumFields()
  5459  		for i := 0; i < n; i++ {
  5460  			ft := t.FieldType(i)
  5461  			if !ft.HasPointers() {
  5462  				continue
  5463  			}
  5464  			addr := s.newValue1I(ssa.OpOffPtr, ft.PtrTo(), t.FieldOff(i), left)
  5465  			val := s.newValue1I(ssa.OpStructSelect, ft, int64(i), right)
  5466  			s.storeTypePtrs(ft, addr, val)
  5467  		}
  5468  	case t.IsArray() && t.NumElem() == 0:
  5469  		// nothing
  5470  	case t.IsArray() && t.NumElem() == 1:
  5471  		s.storeTypePtrs(t.Elem(), left, s.newValue1I(ssa.OpArraySelect, t.Elem(), 0, right))
  5472  	default:
  5473  		s.Fatalf("bad write barrier type %v", t)
  5474  	}
  5475  }
  5476  
  5477  // putArg evaluates n for the purpose of passing it as an argument to a function and returns the value for the call.
  5478  func (s *state) putArg(n ir.Node, t *types.Type) *ssa.Value {
  5479  	var a *ssa.Value
  5480  	if !ssa.CanSSA(t) {
  5481  		a = s.newValue2(ssa.OpDereference, t, s.addr(n), s.mem())
  5482  	} else {
  5483  		a = s.expr(n)
  5484  	}
  5485  	return a
  5486  }
  5487  
  5488  // slice computes the slice v[i:j:k] and returns ptr, len, and cap of result.
  5489  // i,j,k may be nil, in which case they are set to their default value.
  5490  // v may be a slice, string or pointer to an array.
  5491  func (s *state) slice(v, i, j, k *ssa.Value, bounded bool) (p, l, c *ssa.Value) {
  5492  	t := v.Type
  5493  	var ptr, len, cap *ssa.Value
  5494  	switch {
  5495  	case t.IsSlice():
  5496  		ptr = s.newValue1(ssa.OpSlicePtr, types.NewPtr(t.Elem()), v)
  5497  		len = s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], v)
  5498  		cap = s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], v)
  5499  	case t.IsString():
  5500  		ptr = s.newValue1(ssa.OpStringPtr, types.NewPtr(types.Types[types.TUINT8]), v)
  5501  		len = s.newValue1(ssa.OpStringLen, types.Types[types.TINT], v)
  5502  		cap = len
  5503  	case t.IsPtr():
  5504  		if !t.Elem().IsArray() {
  5505  			s.Fatalf("bad ptr to array in slice %v\n", t)
  5506  		}
  5507  		nv := s.nilCheck(v)
  5508  		ptr = s.newValue1(ssa.OpCopy, types.NewPtr(t.Elem().Elem()), nv)
  5509  		len = s.constInt(types.Types[types.TINT], t.Elem().NumElem())
  5510  		cap = len
  5511  	default:
  5512  		s.Fatalf("bad type in slice %v\n", t)
  5513  	}
  5514  
  5515  	// Set default values
  5516  	if i == nil {
  5517  		i = s.constInt(types.Types[types.TINT], 0)
  5518  	}
  5519  	if j == nil {
  5520  		j = len
  5521  	}
  5522  	three := true
  5523  	if k == nil {
  5524  		three = false
  5525  		k = cap
  5526  	}
  5527  
  5528  	// Panic if slice indices are not in bounds.
  5529  	// Make sure we check these in reverse order so that we're always
  5530  	// comparing against a value known to be nonnegative. See issue 28797.
  5531  	if three {
  5532  		if k != cap {
  5533  			kind := ssa.BoundsSlice3Alen
  5534  			if t.IsSlice() {
  5535  				kind = ssa.BoundsSlice3Acap
  5536  			}
  5537  			k = s.boundsCheck(k, cap, kind, bounded)
  5538  		}
  5539  		if j != k {
  5540  			j = s.boundsCheck(j, k, ssa.BoundsSlice3B, bounded)
  5541  		}
  5542  		i = s.boundsCheck(i, j, ssa.BoundsSlice3C, bounded)
  5543  	} else {
  5544  		if j != k {
  5545  			kind := ssa.BoundsSliceAlen
  5546  			if t.IsSlice() {
  5547  				kind = ssa.BoundsSliceAcap
  5548  			}
  5549  			j = s.boundsCheck(j, k, kind, bounded)
  5550  		}
  5551  		i = s.boundsCheck(i, j, ssa.BoundsSliceB, bounded)
  5552  	}
  5553  
  5554  	// Word-sized integer operations.
  5555  	subOp := s.ssaOp(ir.OSUB, types.Types[types.TINT])
  5556  	mulOp := s.ssaOp(ir.OMUL, types.Types[types.TINT])
  5557  	andOp := s.ssaOp(ir.OAND, types.Types[types.TINT])
  5558  
  5559  	// Calculate the length (rlen) and capacity (rcap) of the new slice.
  5560  	// For strings the capacity of the result is unimportant. However,
  5561  	// we use rcap to test if we've generated a zero-length slice.
  5562  	// Use length of strings for that.
  5563  	rlen := s.newValue2(subOp, types.Types[types.TINT], j, i)
  5564  	rcap := rlen
  5565  	if j != k && !t.IsString() {
  5566  		rcap = s.newValue2(subOp, types.Types[types.TINT], k, i)
  5567  	}
  5568  
  5569  	if (i.Op == ssa.OpConst64 || i.Op == ssa.OpConst32) && i.AuxInt == 0 {
  5570  		// No pointer arithmetic necessary.
  5571  		return ptr, rlen, rcap
  5572  	}
  5573  
  5574  	// Calculate the base pointer (rptr) for the new slice.
  5575  	//
  5576  	// Generate the following code assuming that indexes are in bounds.
  5577  	// The masking is to make sure that we don't generate a slice
  5578  	// that points to the next object in memory. We cannot just set
  5579  	// the pointer to nil because then we would create a nil slice or
  5580  	// string.
  5581  	//
  5582  	//     rcap = k - i
  5583  	//     rlen = j - i
  5584  	//     rptr = ptr + (mask(rcap) & (i * stride))
  5585  	//
  5586  	// Where mask(x) is 0 if x==0 and -1 if x>0 and stride is the width
  5587  	// of the element type.
  5588  	stride := s.constInt(types.Types[types.TINT], ptr.Type.Elem().Size())
  5589  
  5590  	// The delta is the number of bytes to offset ptr by.
  5591  	delta := s.newValue2(mulOp, types.Types[types.TINT], i, stride)
  5592  
  5593  	// If we're slicing to the point where the capacity is zero,
  5594  	// zero out the delta.
  5595  	mask := s.newValue1(ssa.OpSlicemask, types.Types[types.TINT], rcap)
  5596  	delta = s.newValue2(andOp, types.Types[types.TINT], delta, mask)
  5597  
  5598  	// Compute rptr = ptr + delta.
  5599  	rptr := s.newValue2(ssa.OpAddPtr, ptr.Type, ptr, delta)
  5600  
  5601  	return rptr, rlen, rcap
  5602  }
  5603  
  5604  type u642fcvtTab struct {
  5605  	leq, cvt2F, and, rsh, or, add ssa.Op
  5606  	one                           func(*state, *types.Type, int64) *ssa.Value
  5607  }
  5608  
  5609  var u64_f64 = u642fcvtTab{
  5610  	leq:   ssa.OpLeq64,
  5611  	cvt2F: ssa.OpCvt64to64F,
  5612  	and:   ssa.OpAnd64,
  5613  	rsh:   ssa.OpRsh64Ux64,
  5614  	or:    ssa.OpOr64,
  5615  	add:   ssa.OpAdd64F,
  5616  	one:   (*state).constInt64,
  5617  }
  5618  
  5619  var u64_f32 = u642fcvtTab{
  5620  	leq:   ssa.OpLeq64,
  5621  	cvt2F: ssa.OpCvt64to32F,
  5622  	and:   ssa.OpAnd64,
  5623  	rsh:   ssa.OpRsh64Ux64,
  5624  	or:    ssa.OpOr64,
  5625  	add:   ssa.OpAdd32F,
  5626  	one:   (*state).constInt64,
  5627  }
  5628  
  5629  func (s *state) uint64Tofloat64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5630  	return s.uint64Tofloat(&u64_f64, n, x, ft, tt)
  5631  }
  5632  
  5633  func (s *state) uint64Tofloat32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5634  	return s.uint64Tofloat(&u64_f32, n, x, ft, tt)
  5635  }
  5636  
  5637  func (s *state) uint64Tofloat(cvttab *u642fcvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5638  	// if x >= 0 {
  5639  	//    result = (floatY) x
  5640  	// } else {
  5641  	// 	  y = uintX(x) ; y = x & 1
  5642  	// 	  z = uintX(x) ; z = z >> 1
  5643  	// 	  z = z | y
  5644  	// 	  result = floatY(z)
  5645  	// 	  result = result + result
  5646  	// }
  5647  	//
  5648  	// Code borrowed from old code generator.
  5649  	// What's going on: large 64-bit "unsigned" looks like
  5650  	// negative number to hardware's integer-to-float
  5651  	// conversion. However, because the mantissa is only
  5652  	// 63 bits, we don't need the LSB, so instead we do an
  5653  	// unsigned right shift (divide by two), convert, and
  5654  	// double. However, before we do that, we need to be
  5655  	// sure that we do not lose a "1" if that made the
  5656  	// difference in the resulting rounding. Therefore, we
  5657  	// preserve it, and OR (not ADD) it back in. The case
  5658  	// that matters is when the eleven discarded bits are
  5659  	// equal to 10000000001; that rounds up, and the 1 cannot
  5660  	// be lost else it would round down if the LSB of the
  5661  	// candidate mantissa is 0.
  5662  
  5663  	cmp := s.newValue2(cvttab.leq, types.Types[types.TBOOL], s.zeroVal(ft), x)
  5664  
  5665  	b := s.endBlock()
  5666  	b.Kind = ssa.BlockIf
  5667  	b.SetControl(cmp)
  5668  	b.Likely = ssa.BranchLikely
  5669  
  5670  	bThen := s.f.NewBlock(ssa.BlockPlain)
  5671  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5672  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5673  
  5674  	b.AddEdgeTo(bThen)
  5675  	s.startBlock(bThen)
  5676  	a0 := s.newValue1(cvttab.cvt2F, tt, x)
  5677  	s.vars[n] = a0
  5678  	s.endBlock()
  5679  	bThen.AddEdgeTo(bAfter)
  5680  
  5681  	b.AddEdgeTo(bElse)
  5682  	s.startBlock(bElse)
  5683  	one := cvttab.one(s, ft, 1)
  5684  	y := s.newValue2(cvttab.and, ft, x, one)
  5685  	z := s.newValue2(cvttab.rsh, ft, x, one)
  5686  	z = s.newValue2(cvttab.or, ft, z, y)
  5687  	a := s.newValue1(cvttab.cvt2F, tt, z)
  5688  	a1 := s.newValue2(cvttab.add, tt, a, a)
  5689  	s.vars[n] = a1
  5690  	s.endBlock()
  5691  	bElse.AddEdgeTo(bAfter)
  5692  
  5693  	s.startBlock(bAfter)
  5694  	return s.variable(n, n.Type())
  5695  }
  5696  
  5697  type u322fcvtTab struct {
  5698  	cvtI2F, cvtF2F ssa.Op
  5699  }
  5700  
  5701  var u32_f64 = u322fcvtTab{
  5702  	cvtI2F: ssa.OpCvt32to64F,
  5703  	cvtF2F: ssa.OpCopy,
  5704  }
  5705  
  5706  var u32_f32 = u322fcvtTab{
  5707  	cvtI2F: ssa.OpCvt32to32F,
  5708  	cvtF2F: ssa.OpCvt64Fto32F,
  5709  }
  5710  
  5711  func (s *state) uint32Tofloat64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5712  	return s.uint32Tofloat(&u32_f64, n, x, ft, tt)
  5713  }
  5714  
  5715  func (s *state) uint32Tofloat32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5716  	return s.uint32Tofloat(&u32_f32, n, x, ft, tt)
  5717  }
  5718  
  5719  func (s *state) uint32Tofloat(cvttab *u322fcvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5720  	// if x >= 0 {
  5721  	// 	result = floatY(x)
  5722  	// } else {
  5723  	// 	result = floatY(float64(x) + (1<<32))
  5724  	// }
  5725  	cmp := s.newValue2(ssa.OpLeq32, types.Types[types.TBOOL], s.zeroVal(ft), x)
  5726  	b := s.endBlock()
  5727  	b.Kind = ssa.BlockIf
  5728  	b.SetControl(cmp)
  5729  	b.Likely = ssa.BranchLikely
  5730  
  5731  	bThen := s.f.NewBlock(ssa.BlockPlain)
  5732  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5733  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5734  
  5735  	b.AddEdgeTo(bThen)
  5736  	s.startBlock(bThen)
  5737  	a0 := s.newValue1(cvttab.cvtI2F, tt, x)
  5738  	s.vars[n] = a0
  5739  	s.endBlock()
  5740  	bThen.AddEdgeTo(bAfter)
  5741  
  5742  	b.AddEdgeTo(bElse)
  5743  	s.startBlock(bElse)
  5744  	a1 := s.newValue1(ssa.OpCvt32to64F, types.Types[types.TFLOAT64], x)
  5745  	twoToThe32 := s.constFloat64(types.Types[types.TFLOAT64], float64(1<<32))
  5746  	a2 := s.newValue2(ssa.OpAdd64F, types.Types[types.TFLOAT64], a1, twoToThe32)
  5747  	a3 := s.newValue1(cvttab.cvtF2F, tt, a2)
  5748  
  5749  	s.vars[n] = a3
  5750  	s.endBlock()
  5751  	bElse.AddEdgeTo(bAfter)
  5752  
  5753  	s.startBlock(bAfter)
  5754  	return s.variable(n, n.Type())
  5755  }
  5756  
  5757  // referenceTypeBuiltin generates code for the len/cap builtins for maps and channels.
  5758  func (s *state) referenceTypeBuiltin(n *ir.UnaryExpr, x *ssa.Value) *ssa.Value {
  5759  	if !n.X.Type().IsMap() && !n.X.Type().IsChan() {
  5760  		s.Fatalf("node must be a map or a channel")
  5761  	}
  5762  	if n.X.Type().IsChan() && n.Op() == ir.OLEN {
  5763  		s.Fatalf("cannot inline len(chan)") // must use runtime.chanlen now
  5764  	}
  5765  	if n.X.Type().IsChan() && n.Op() == ir.OCAP {
  5766  		s.Fatalf("cannot inline cap(chan)") // must use runtime.chancap now
  5767  	}
  5768  	if n.X.Type().IsMap() && n.Op() == ir.OCAP {
  5769  		s.Fatalf("cannot inline cap(map)") // cap(map) does not exist
  5770  	}
  5771  	// if n == nil {
  5772  	//   return 0
  5773  	// } else {
  5774  	//   // len, the actual loadType depends
  5775  	//   return int(*((*loadType)n))
  5776  	//   // cap (chan only, not used for now)
  5777  	//   return *(((*int)n)+1)
  5778  	// }
  5779  	lenType := n.Type()
  5780  	nilValue := s.constNil(types.Types[types.TUINTPTR])
  5781  	cmp := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], x, nilValue)
  5782  	b := s.endBlock()
  5783  	b.Kind = ssa.BlockIf
  5784  	b.SetControl(cmp)
  5785  	b.Likely = ssa.BranchUnlikely
  5786  
  5787  	bThen := s.f.NewBlock(ssa.BlockPlain)
  5788  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5789  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5790  
  5791  	// length/capacity of a nil map/chan is zero
  5792  	b.AddEdgeTo(bThen)
  5793  	s.startBlock(bThen)
  5794  	s.vars[n] = s.zeroVal(lenType)
  5795  	s.endBlock()
  5796  	bThen.AddEdgeTo(bAfter)
  5797  
  5798  	b.AddEdgeTo(bElse)
  5799  	s.startBlock(bElse)
  5800  	switch n.Op() {
  5801  	case ir.OLEN:
  5802  		if n.X.Type().IsMap() {
  5803  			// length is stored in the first word, but needs conversion to int.
  5804  			loadType := reflectdata.MapType().Field(0).Type // uint64
  5805  			load := s.load(loadType, x)
  5806  			s.vars[n] = s.conv(nil, load, loadType, lenType) // integer conversion doesn't need Node
  5807  		} else {
  5808  			// length is stored in the first word for chan, no conversion needed.
  5809  			s.vars[n] = s.load(lenType, x)
  5810  		}
  5811  	case ir.OCAP:
  5812  		// capacity is stored in the second word for chan
  5813  		sw := s.newValue1I(ssa.OpOffPtr, lenType.PtrTo(), lenType.Size(), x)
  5814  		s.vars[n] = s.load(lenType, sw)
  5815  	default:
  5816  		s.Fatalf("op must be OLEN or OCAP")
  5817  	}
  5818  	s.endBlock()
  5819  	bElse.AddEdgeTo(bAfter)
  5820  
  5821  	s.startBlock(bAfter)
  5822  	return s.variable(n, lenType)
  5823  }
  5824  
  5825  type f2uCvtTab struct {
  5826  	ltf, cvt2U, subf, or ssa.Op
  5827  	floatValue           func(*state, *types.Type, float64) *ssa.Value
  5828  	intValue             func(*state, *types.Type, int64) *ssa.Value
  5829  	cutoff               uint64
  5830  }
  5831  
  5832  var f32_u64 = f2uCvtTab{
  5833  	ltf:        ssa.OpLess32F,
  5834  	cvt2U:      ssa.OpCvt32Fto64,
  5835  	subf:       ssa.OpSub32F,
  5836  	or:         ssa.OpOr64,
  5837  	floatValue: (*state).constFloat32,
  5838  	intValue:   (*state).constInt64,
  5839  	cutoff:     1 << 63,
  5840  }
  5841  
  5842  var f64_u64 = f2uCvtTab{
  5843  	ltf:        ssa.OpLess64F,
  5844  	cvt2U:      ssa.OpCvt64Fto64,
  5845  	subf:       ssa.OpSub64F,
  5846  	or:         ssa.OpOr64,
  5847  	floatValue: (*state).constFloat64,
  5848  	intValue:   (*state).constInt64,
  5849  	cutoff:     1 << 63,
  5850  }
  5851  
  5852  var f32_u32 = f2uCvtTab{
  5853  	ltf:        ssa.OpLess32F,
  5854  	cvt2U:      ssa.OpCvt32Fto32,
  5855  	subf:       ssa.OpSub32F,
  5856  	or:         ssa.OpOr32,
  5857  	floatValue: (*state).constFloat32,
  5858  	intValue:   func(s *state, t *types.Type, v int64) *ssa.Value { return s.constInt32(t, int32(v)) },
  5859  	cutoff:     1 << 31,
  5860  }
  5861  
  5862  var f64_u32 = f2uCvtTab{
  5863  	ltf:        ssa.OpLess64F,
  5864  	cvt2U:      ssa.OpCvt64Fto32,
  5865  	subf:       ssa.OpSub64F,
  5866  	or:         ssa.OpOr32,
  5867  	floatValue: (*state).constFloat64,
  5868  	intValue:   func(s *state, t *types.Type, v int64) *ssa.Value { return s.constInt32(t, int32(v)) },
  5869  	cutoff:     1 << 31,
  5870  }
  5871  
  5872  func (s *state) float32ToUint64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5873  	return s.floatToUint(&f32_u64, n, x, ft, tt)
  5874  }
  5875  func (s *state) float64ToUint64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5876  	return s.floatToUint(&f64_u64, n, x, ft, tt)
  5877  }
  5878  
  5879  func (s *state) float32ToUint32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5880  	return s.floatToUint(&f32_u32, n, x, ft, tt)
  5881  }
  5882  
  5883  func (s *state) float64ToUint32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5884  	return s.floatToUint(&f64_u32, n, x, ft, tt)
  5885  }
  5886  
  5887  func (s *state) floatToUint(cvttab *f2uCvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5888  	// cutoff:=1<<(intY_Size-1)
  5889  	// if x < floatX(cutoff) {
  5890  	// 	result = uintY(x) // bThen
  5891  	//  // gated by ConvertHash, clamp negative inputs to zero
  5892  	// 	if x < 0 { // unlikely
  5893  	// 		result = 0 // bZero
  5894  	// 	}
  5895  	// } else {
  5896  	// 	y = x - floatX(cutoff) // bElse
  5897  	// 	z = uintY(y)
  5898  	// 	result = z | -(cutoff)
  5899  	// }
  5900  
  5901  	cutoff := cvttab.floatValue(s, ft, float64(cvttab.cutoff))
  5902  	cmp := s.newValueOrSfCall2(cvttab.ltf, types.Types[types.TBOOL], x, cutoff)
  5903  	b := s.endBlock()
  5904  	b.Kind = ssa.BlockIf
  5905  	b.SetControl(cmp)
  5906  	b.Likely = ssa.BranchLikely
  5907  
  5908  	var bThen, bZero *ssa.Block
  5909  	// use salted hash to distinguish unsigned convert at a Pos from signed convert at a Pos
  5910  	newConversion := base.ConvertHash.MatchPosWithInfo(n.Pos(), "U", nil)
  5911  	if newConversion {
  5912  		bZero = s.f.NewBlock(ssa.BlockPlain)
  5913  		bThen = s.f.NewBlock(ssa.BlockIf)
  5914  	} else {
  5915  		bThen = s.f.NewBlock(ssa.BlockPlain)
  5916  	}
  5917  
  5918  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5919  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5920  
  5921  	b.AddEdgeTo(bThen)
  5922  	s.startBlock(bThen)
  5923  	a0 := s.newValueOrSfCall1(cvttab.cvt2U, tt, x)
  5924  	s.vars[n] = a0
  5925  
  5926  	if newConversion {
  5927  		cmpz := s.newValueOrSfCall2(cvttab.ltf, types.Types[types.TBOOL], x, cvttab.floatValue(s, ft, 0.0))
  5928  		s.endBlock()
  5929  		bThen.SetControl(cmpz)
  5930  		bThen.AddEdgeTo(bZero)
  5931  		bThen.Likely = ssa.BranchUnlikely
  5932  		bThen.AddEdgeTo(bAfter)
  5933  
  5934  		s.startBlock(bZero)
  5935  		s.vars[n] = cvttab.intValue(s, tt, 0)
  5936  		s.endBlock()
  5937  		bZero.AddEdgeTo(bAfter)
  5938  	} else {
  5939  		s.endBlock()
  5940  		bThen.AddEdgeTo(bAfter)
  5941  	}
  5942  
  5943  	b.AddEdgeTo(bElse)
  5944  	s.startBlock(bElse)
  5945  	y := s.newValueOrSfCall2(cvttab.subf, ft, x, cutoff)
  5946  	y = s.newValueOrSfCall1(cvttab.cvt2U, tt, y)
  5947  	z := cvttab.intValue(s, tt, int64(-cvttab.cutoff))
  5948  	a1 := s.newValue2(cvttab.or, tt, y, z)
  5949  	s.vars[n] = a1
  5950  	s.endBlock()
  5951  	bElse.AddEdgeTo(bAfter)
  5952  
  5953  	s.startBlock(bAfter)
  5954  	return s.variable(n, n.Type())
  5955  }
  5956  
  5957  // dottype generates SSA for a type assertion node.
  5958  // commaok indicates whether to panic or return a bool.
  5959  // If commaok is false, resok will be nil.
  5960  func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
  5961  	iface := s.expr(n.X)              // input interface
  5962  	target := s.reflectType(n.Type()) // target type
  5963  	var targetItab *ssa.Value
  5964  	if n.ITab != nil {
  5965  		targetItab = s.expr(n.ITab)
  5966  	}
  5967  
  5968  	if n.UseNilPanic {
  5969  		if commaok {
  5970  			base.Fatalf("unexpected *ir.TypeAssertExpr with UseNilPanic == true && commaok == true")
  5971  		}
  5972  		if n.Type().IsInterface() {
  5973  			// Currently we do not expect the compiler to emit type asserts with UseNilPanic, that assert to an interface type.
  5974  			// If needed, this can be relaxed in the future, but for now we can assert that.
  5975  			base.Fatalf("unexpected *ir.TypeAssertExpr with UseNilPanic == true && Type().IsInterface() == true")
  5976  		}
  5977  		typs := s.f.Config.Types
  5978  		iface = s.newValue2(
  5979  			ssa.OpIMake,
  5980  			iface.Type,
  5981  			s.nilCheck(s.newValue1(ssa.OpITab, typs.BytePtr, iface)),
  5982  			s.newValue1(ssa.OpIData, typs.BytePtr, iface),
  5983  		)
  5984  	}
  5985  
  5986  	return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, nil, target, targetItab, commaok, n.Descriptor)
  5987  }
  5988  
  5989  func (s *state) dynamicDottype(n *ir.DynamicTypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
  5990  	iface := s.expr(n.X)
  5991  	var source, target, targetItab *ssa.Value
  5992  	if n.SrcRType != nil {
  5993  		source = s.expr(n.SrcRType)
  5994  	}
  5995  	if !n.X.Type().IsEmptyInterface() && !n.Type().IsInterface() {
  5996  		byteptr := s.f.Config.Types.BytePtr
  5997  		targetItab = s.expr(n.ITab)
  5998  		// TODO(mdempsky): Investigate whether compiling n.RType could be
  5999  		// better than loading itab.typ.
  6000  		target = s.load(byteptr, s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), targetItab))
  6001  	} else {
  6002  		target = s.expr(n.RType)
  6003  	}
  6004  	return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, source, target, targetItab, commaok, nil)
  6005  }
  6006  
  6007  // dottype1 implements a x.(T) operation. iface is the argument (x), dst is the type we're asserting to (T)
  6008  // and src is the type we're asserting from.
  6009  // source is the *runtime._type of src
  6010  // target is the *runtime._type of dst.
  6011  // If src is a nonempty interface and dst is not an interface, targetItab is an itab representing (dst, src). Otherwise it is nil.
  6012  // commaok is true if the caller wants a boolean success value. Otherwise, the generated code panics if the conversion fails.
  6013  // descriptor is a compiler-allocated internal/abi.TypeAssert whose address is passed to runtime.typeAssert when
  6014  // the target type is a compile-time-known non-empty interface. It may be nil.
  6015  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) {
  6016  	typs := s.f.Config.Types
  6017  	byteptr := typs.BytePtr
  6018  	if dst.IsInterface() {
  6019  		if dst.IsEmptyInterface() {
  6020  			// Converting to an empty interface.
  6021  			// Input could be an empty or nonempty interface.
  6022  			if base.Debug.TypeAssert > 0 {
  6023  				base.WarnfAt(pos, "type assertion inlined")
  6024  			}
  6025  
  6026  			// Get itab/type field from input.
  6027  			itab := s.newValue1(ssa.OpITab, byteptr, iface)
  6028  			// Conversion succeeds iff that field is not nil.
  6029  			cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  6030  
  6031  			if src.IsEmptyInterface() && commaok {
  6032  				// Converting empty interface to empty interface with ,ok is just a nil check.
  6033  				return iface, cond
  6034  			}
  6035  
  6036  			// Branch on nilness.
  6037  			b := s.endBlock()
  6038  			b.Kind = ssa.BlockIf
  6039  			b.SetControl(cond)
  6040  			b.Likely = ssa.BranchLikely
  6041  			bOk := s.f.NewBlock(ssa.BlockPlain)
  6042  			bFail := s.f.NewBlock(ssa.BlockPlain)
  6043  			b.AddEdgeTo(bOk)
  6044  			b.AddEdgeTo(bFail)
  6045  
  6046  			if !commaok {
  6047  				// On failure, panic by calling panicnildottype.
  6048  				s.startBlock(bFail)
  6049  				s.rtcall(ir.Syms.Panicnildottype, false, nil, target)
  6050  
  6051  				// On success, return (perhaps modified) input interface.
  6052  				s.startBlock(bOk)
  6053  				if src.IsEmptyInterface() {
  6054  					res = iface // Use input interface unchanged.
  6055  					return
  6056  				}
  6057  				// Load type out of itab, build interface with existing idata.
  6058  				off := s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab)
  6059  				typ := s.load(byteptr, off)
  6060  				idata := s.newValue1(ssa.OpIData, byteptr, iface)
  6061  				res = s.newValue2(ssa.OpIMake, dst, typ, idata)
  6062  				return
  6063  			}
  6064  
  6065  			s.startBlock(bOk)
  6066  			// nonempty -> empty
  6067  			// Need to load type from itab
  6068  			off := s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab)
  6069  			s.vars[typVar] = s.load(byteptr, off)
  6070  			s.endBlock()
  6071  
  6072  			// itab is nil, might as well use that as the nil result.
  6073  			s.startBlock(bFail)
  6074  			s.vars[typVar] = itab
  6075  			s.endBlock()
  6076  
  6077  			// Merge point.
  6078  			bEnd := s.f.NewBlock(ssa.BlockPlain)
  6079  			bOk.AddEdgeTo(bEnd)
  6080  			bFail.AddEdgeTo(bEnd)
  6081  			s.startBlock(bEnd)
  6082  			idata := s.newValue1(ssa.OpIData, byteptr, iface)
  6083  			res = s.newValue2(ssa.OpIMake, dst, s.variable(typVar, byteptr), idata)
  6084  			resok = cond
  6085  			delete(s.vars, typVar) // no practical effect, just to indicate typVar is no longer live.
  6086  			return
  6087  		}
  6088  		// converting to a nonempty interface needs a runtime call.
  6089  		if base.Debug.TypeAssert > 0 {
  6090  			base.WarnfAt(pos, "type assertion not inlined")
  6091  		}
  6092  
  6093  		itab := s.newValue1(ssa.OpITab, byteptr, iface)
  6094  		data := s.newValue1(ssa.OpIData, types.Types[types.TUNSAFEPTR], iface)
  6095  
  6096  		// First, check for nil.
  6097  		bNil := s.f.NewBlock(ssa.BlockPlain)
  6098  		bNonNil := s.f.NewBlock(ssa.BlockPlain)
  6099  		bMerge := s.f.NewBlock(ssa.BlockPlain)
  6100  		cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  6101  		b := s.endBlock()
  6102  		b.Kind = ssa.BlockIf
  6103  		b.SetControl(cond)
  6104  		b.Likely = ssa.BranchLikely
  6105  		b.AddEdgeTo(bNonNil)
  6106  		b.AddEdgeTo(bNil)
  6107  
  6108  		s.startBlock(bNil)
  6109  		if commaok {
  6110  			s.vars[typVar] = itab // which will be nil
  6111  			b := s.endBlock()
  6112  			b.AddEdgeTo(bMerge)
  6113  		} else {
  6114  			// Panic if input is nil.
  6115  			s.rtcall(ir.Syms.Panicnildottype, false, nil, target)
  6116  		}
  6117  
  6118  		// Get typ, possibly by loading out of itab.
  6119  		s.startBlock(bNonNil)
  6120  		typ := itab
  6121  		if !src.IsEmptyInterface() {
  6122  			typ = s.load(byteptr, s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab))
  6123  		}
  6124  
  6125  		// Check the cache first.
  6126  		var d *ssa.Value
  6127  		if descriptor != nil {
  6128  			d = s.newValue1A(ssa.OpAddr, byteptr, descriptor, s.sb)
  6129  			if base.Flag.N == 0 && rtabi.UseInterfaceSwitchCache(Arch.LinkArch.Family) {
  6130  				// Note: we can only use the cache if we have the right atomic load instruction.
  6131  				// Double-check that here.
  6132  				if intrinsics.lookup(Arch.LinkArch.Arch, "internal/runtime/atomic", "Loadp") == nil {
  6133  					s.Fatalf("atomic load not available")
  6134  				}
  6135  				// Pick right size ops.
  6136  				var mul, and, add, zext ssa.Op
  6137  				if s.config.PtrSize == 4 {
  6138  					mul = ssa.OpMul32
  6139  					and = ssa.OpAnd32
  6140  					add = ssa.OpAdd32
  6141  					zext = ssa.OpCopy
  6142  				} else {
  6143  					mul = ssa.OpMul64
  6144  					and = ssa.OpAnd64
  6145  					add = ssa.OpAdd64
  6146  					zext = ssa.OpZeroExt32to64
  6147  				}
  6148  
  6149  				loopHead := s.f.NewBlock(ssa.BlockPlain)
  6150  				loopBody := s.f.NewBlock(ssa.BlockPlain)
  6151  				cacheHit := s.f.NewBlock(ssa.BlockPlain)
  6152  				cacheMiss := s.f.NewBlock(ssa.BlockPlain)
  6153  
  6154  				// Load cache pointer out of descriptor, with an atomic load so
  6155  				// we ensure that we see a fully written cache.
  6156  				atomicLoad := s.newValue2(ssa.OpAtomicLoadPtr, types.NewTuple(typs.BytePtr, types.TypeMem), d, s.mem())
  6157  				cache := s.newValue1(ssa.OpSelect0, typs.BytePtr, atomicLoad)
  6158  				s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, atomicLoad)
  6159  
  6160  				// Load hash from type or itab.
  6161  				var hash *ssa.Value
  6162  				if src.IsEmptyInterface() {
  6163  					hash = s.newValue2(ssa.OpLoad, typs.UInt32, s.newValue1I(ssa.OpOffPtr, typs.UInt32Ptr, rttype.Type.OffsetOf("Hash"), typ), s.mem())
  6164  				} else {
  6165  					hash = s.newValue2(ssa.OpLoad, typs.UInt32, s.newValue1I(ssa.OpOffPtr, typs.UInt32Ptr, rttype.ITab.OffsetOf("Hash"), itab), s.mem())
  6166  				}
  6167  				hash = s.newValue1(zext, typs.Uintptr, hash)
  6168  				s.vars[hashVar] = hash
  6169  				// Load mask from cache.
  6170  				mask := s.newValue2(ssa.OpLoad, typs.Uintptr, cache, s.mem())
  6171  				// Jump to loop head.
  6172  				b := s.endBlock()
  6173  				b.AddEdgeTo(loopHead)
  6174  
  6175  				// At loop head, get pointer to the cache entry.
  6176  				//   e := &cache.Entries[hash&mask]
  6177  				s.startBlock(loopHead)
  6178  				idx := s.newValue2(and, typs.Uintptr, s.variable(hashVar, typs.Uintptr), mask)
  6179  				idx = s.newValue2(mul, typs.Uintptr, idx, s.uintptrConstant(uint64(2*s.config.PtrSize)))
  6180  				idx = s.newValue2(add, typs.Uintptr, idx, s.uintptrConstant(uint64(s.config.PtrSize)))
  6181  				e := s.newValue2(ssa.OpAddPtr, typs.UintptrPtr, cache, idx)
  6182  				//   hash++
  6183  				s.vars[hashVar] = s.newValue2(add, typs.Uintptr, s.variable(hashVar, typs.Uintptr), s.uintptrConstant(1))
  6184  
  6185  				// Look for a cache hit.
  6186  				//   if e.Typ == typ { goto hit }
  6187  				eTyp := s.newValue2(ssa.OpLoad, typs.Uintptr, e, s.mem())
  6188  				cmp1 := s.newValue2(ssa.OpEqPtr, typs.Bool, typ, eTyp)
  6189  				b = s.endBlock()
  6190  				b.Kind = ssa.BlockIf
  6191  				b.SetControl(cmp1)
  6192  				b.AddEdgeTo(cacheHit)
  6193  				b.AddEdgeTo(loopBody)
  6194  
  6195  				// Look for an empty entry, the tombstone for this hash table.
  6196  				//   if e.Typ == nil { goto miss }
  6197  				s.startBlock(loopBody)
  6198  				cmp2 := s.newValue2(ssa.OpEqPtr, typs.Bool, eTyp, s.constNil(typs.BytePtr))
  6199  				b = s.endBlock()
  6200  				b.Kind = ssa.BlockIf
  6201  				b.SetControl(cmp2)
  6202  				b.AddEdgeTo(cacheMiss)
  6203  				b.AddEdgeTo(loopHead)
  6204  
  6205  				// On a hit, load the data fields of the cache entry.
  6206  				//   Itab = e.Itab
  6207  				s.startBlock(cacheHit)
  6208  				eItab := s.newValue2(ssa.OpLoad, typs.BytePtr, s.newValue1I(ssa.OpOffPtr, typs.BytePtrPtr, s.config.PtrSize, e), s.mem())
  6209  				s.vars[typVar] = eItab
  6210  				b = s.endBlock()
  6211  				b.AddEdgeTo(bMerge)
  6212  
  6213  				// On a miss, call into the runtime to get the answer.
  6214  				s.startBlock(cacheMiss)
  6215  			}
  6216  		}
  6217  
  6218  		// Call into runtime to get itab for result.
  6219  		if descriptor != nil {
  6220  			itab = s.rtcall(ir.Syms.TypeAssert, true, []*types.Type{byteptr}, d, typ)[0]
  6221  		} else {
  6222  			var fn *obj.LSym
  6223  			if commaok {
  6224  				fn = ir.Syms.AssertE2I2
  6225  			} else {
  6226  				fn = ir.Syms.AssertE2I
  6227  			}
  6228  			itab = s.rtcall(fn, true, []*types.Type{byteptr}, target, typ)[0]
  6229  		}
  6230  		s.vars[typVar] = itab
  6231  		b = s.endBlock()
  6232  		b.AddEdgeTo(bMerge)
  6233  
  6234  		// Build resulting interface.
  6235  		s.startBlock(bMerge)
  6236  		itab = s.variable(typVar, byteptr)
  6237  		var ok *ssa.Value
  6238  		if commaok {
  6239  			ok = s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  6240  		}
  6241  		return s.newValue2(ssa.OpIMake, dst, itab, data), ok
  6242  	}
  6243  
  6244  	if base.Debug.TypeAssert > 0 {
  6245  		base.WarnfAt(pos, "type assertion inlined")
  6246  	}
  6247  
  6248  	// Converting to a concrete type.
  6249  	direct := types.IsDirectIface(dst)
  6250  	itab := s.newValue1(ssa.OpITab, byteptr, iface) // type word of interface
  6251  	if base.Debug.TypeAssert > 0 {
  6252  		base.WarnfAt(pos, "type assertion inlined")
  6253  	}
  6254  	var wantedFirstWord *ssa.Value
  6255  	if src.IsEmptyInterface() {
  6256  		// Looking for pointer to target type.
  6257  		wantedFirstWord = target
  6258  	} else {
  6259  		// Looking for pointer to itab for target type and source interface.
  6260  		wantedFirstWord = targetItab
  6261  	}
  6262  
  6263  	var tmp ir.Node     // temporary for use with large types
  6264  	var addr *ssa.Value // address of tmp
  6265  	if commaok && !ssa.CanSSA(dst) {
  6266  		// unSSAable type, use temporary.
  6267  		// TODO: get rid of some of these temporaries.
  6268  		tmp, addr = s.temp(pos, dst)
  6269  	}
  6270  
  6271  	cond := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], itab, wantedFirstWord)
  6272  	b := s.endBlock()
  6273  	b.Kind = ssa.BlockIf
  6274  	b.SetControl(cond)
  6275  	b.Likely = ssa.BranchLikely
  6276  
  6277  	bOk := s.f.NewBlock(ssa.BlockPlain)
  6278  	bFail := s.f.NewBlock(ssa.BlockPlain)
  6279  	b.AddEdgeTo(bOk)
  6280  	b.AddEdgeTo(bFail)
  6281  
  6282  	if !commaok {
  6283  		// on failure, panic by calling panicdottype
  6284  		s.startBlock(bFail)
  6285  		taddr := source
  6286  		if taddr == nil {
  6287  			taddr = s.reflectType(src)
  6288  		}
  6289  		if src.IsEmptyInterface() {
  6290  			s.rtcall(ir.Syms.PanicdottypeE, false, nil, itab, target, taddr)
  6291  		} else {
  6292  			s.rtcall(ir.Syms.PanicdottypeI, false, nil, itab, target, taddr)
  6293  		}
  6294  
  6295  		// on success, return data from interface
  6296  		s.startBlock(bOk)
  6297  		if direct {
  6298  			return s.newValue1(ssa.OpIData, dst, iface), nil
  6299  		}
  6300  		p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
  6301  		return s.load(dst, p), nil
  6302  	}
  6303  
  6304  	// commaok is the more complicated case because we have
  6305  	// a control flow merge point.
  6306  	bEnd := s.f.NewBlock(ssa.BlockPlain)
  6307  	// Note that we need a new valVar each time (unlike okVar where we can
  6308  	// reuse the variable) because it might have a different type every time.
  6309  	valVar := ssaMarker("val")
  6310  
  6311  	// type assertion succeeded
  6312  	s.startBlock(bOk)
  6313  	if tmp == nil {
  6314  		if direct {
  6315  			s.vars[valVar] = s.newValue1(ssa.OpIData, dst, iface)
  6316  		} else {
  6317  			p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
  6318  			s.vars[valVar] = s.load(dst, p)
  6319  		}
  6320  	} else {
  6321  		p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
  6322  		s.move(dst, addr, p)
  6323  	}
  6324  	s.vars[okVar] = s.constBool(true)
  6325  	s.endBlock()
  6326  	bOk.AddEdgeTo(bEnd)
  6327  
  6328  	// type assertion failed
  6329  	s.startBlock(bFail)
  6330  	if tmp == nil {
  6331  		s.vars[valVar] = s.zeroVal(dst)
  6332  	} else {
  6333  		s.zero(dst, addr)
  6334  	}
  6335  	s.vars[okVar] = s.constBool(false)
  6336  	s.endBlock()
  6337  	bFail.AddEdgeTo(bEnd)
  6338  
  6339  	// merge point
  6340  	s.startBlock(bEnd)
  6341  	if tmp == nil {
  6342  		res = s.variable(valVar, dst)
  6343  		delete(s.vars, valVar) // no practical effect, just to indicate typVar is no longer live.
  6344  	} else {
  6345  		res = s.load(dst, addr)
  6346  	}
  6347  	resok = s.variable(okVar, types.Types[types.TBOOL])
  6348  	delete(s.vars, okVar) // ditto
  6349  	return res, resok
  6350  }
  6351  
  6352  // temp allocates a temp of type t at position pos
  6353  func (s *state) temp(pos src.XPos, t *types.Type) (*ir.Name, *ssa.Value) {
  6354  	tmp := typecheck.TempAt(pos, s.curfn, t)
  6355  	if t.HasPointers() || (ssa.IsMergeCandidate(tmp) && t != deferstruct()) {
  6356  		s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, tmp, s.mem())
  6357  	}
  6358  	addr := s.addr(tmp)
  6359  	return tmp, addr
  6360  }
  6361  
  6362  // variable returns the value of a variable at the current location.
  6363  func (s *state) variable(n ir.Node, t *types.Type) *ssa.Value {
  6364  	v := s.vars[n]
  6365  	if v != nil {
  6366  		return v
  6367  	}
  6368  	v = s.fwdVars[n]
  6369  	if v != nil {
  6370  		return v
  6371  	}
  6372  
  6373  	if s.curBlock == s.f.Entry {
  6374  		// No variable should be live at entry.
  6375  		s.f.Fatalf("value %v (%v) incorrectly live at entry", n, v)
  6376  	}
  6377  	// Make a FwdRef, which records a value that's live on block input.
  6378  	// We'll find the matching definition as part of insertPhis.
  6379  	v = s.newValue0A(ssa.OpFwdRef, t, fwdRefAux{N: n})
  6380  	s.fwdVars[n] = v
  6381  	if n.Op() == ir.ONAME {
  6382  		s.addNamedValue(n.(*ir.Name), v)
  6383  	}
  6384  	return v
  6385  }
  6386  
  6387  func (s *state) mem() *ssa.Value {
  6388  	return s.variable(memVar, types.TypeMem)
  6389  }
  6390  
  6391  func (s *state) addNamedValue(n *ir.Name, v *ssa.Value) {
  6392  	if n.Class == ir.Pxxx {
  6393  		// Don't track our marker nodes (memVar etc.).
  6394  		return
  6395  	}
  6396  	if ir.IsAutoTmp(n) {
  6397  		// Don't track temporary variables.
  6398  		return
  6399  	}
  6400  	if n.Class == ir.PPARAMOUT {
  6401  		// Don't track named output values.  This prevents return values
  6402  		// from being assigned too early. See #14591 and #14762. TODO: allow this.
  6403  		return
  6404  	}
  6405  	loc := ssa.LocalSlot{N: n, Type: n.Type(), Off: 0}
  6406  	values, ok := s.f.NamedValues[loc]
  6407  	if !ok {
  6408  		s.f.Names = append(s.f.Names, &loc)
  6409  		s.f.CanonicalLocalSlots[loc] = &loc
  6410  	}
  6411  	s.f.NamedValues[loc] = append(values, v)
  6412  }
  6413  
  6414  // Branch is an unresolved branch.
  6415  type Branch struct {
  6416  	P *obj.Prog  // branch instruction
  6417  	B *ssa.Block // target
  6418  }
  6419  
  6420  // State contains state needed during Prog generation.
  6421  type State struct {
  6422  	ABI obj.ABI
  6423  
  6424  	pp *objw.Progs
  6425  
  6426  	// Branches remembers all the branch instructions we've seen
  6427  	// and where they would like to go.
  6428  	Branches []Branch
  6429  
  6430  	// JumpTables remembers all the jump tables we've seen.
  6431  	JumpTables []*ssa.Block
  6432  
  6433  	// bstart remembers where each block starts (indexed by block ID)
  6434  	bstart []*obj.Prog
  6435  
  6436  	maxarg int64 // largest frame size for arguments to calls made by the function
  6437  
  6438  	// Map from GC safe points to liveness index, generated by
  6439  	// liveness analysis.
  6440  	livenessMap liveness.Map
  6441  
  6442  	// partLiveArgs includes arguments that may be partially live, for which we
  6443  	// need to generate instructions that spill the argument registers.
  6444  	partLiveArgs map[*ir.Name]bool
  6445  
  6446  	// lineRunStart records the beginning of the current run of instructions
  6447  	// within a single block sharing the same line number
  6448  	// Used to move statement marks to the beginning of such runs.
  6449  	lineRunStart *obj.Prog
  6450  
  6451  	// wasm: The number of values on the WebAssembly stack. This is only used as a safeguard.
  6452  	OnWasmStackSkipped int
  6453  }
  6454  
  6455  func (s *State) FuncInfo() *obj.FuncInfo {
  6456  	return s.pp.CurFunc.LSym.Func()
  6457  }
  6458  
  6459  // Prog appends a new Prog.
  6460  func (s *State) Prog(as obj.As) *obj.Prog {
  6461  	p := s.pp.Prog(as)
  6462  	if objw.LosesStmtMark(as) {
  6463  		return p
  6464  	}
  6465  	// Float a statement start to the beginning of any same-line run.
  6466  	// lineRunStart is reset at block boundaries, which appears to work well.
  6467  	if s.lineRunStart == nil || s.lineRunStart.Pos.Line() != p.Pos.Line() {
  6468  		s.lineRunStart = p
  6469  	} else if p.Pos.IsStmt() == src.PosIsStmt {
  6470  		s.lineRunStart.Pos = s.lineRunStart.Pos.WithIsStmt()
  6471  		p.Pos = p.Pos.WithNotStmt()
  6472  	}
  6473  	return p
  6474  }
  6475  
  6476  // Pc returns the current Prog.
  6477  func (s *State) Pc() *obj.Prog {
  6478  	return s.pp.Next
  6479  }
  6480  
  6481  // SetPos sets the current source position.
  6482  func (s *State) SetPos(pos src.XPos) {
  6483  	s.pp.Pos = pos
  6484  }
  6485  
  6486  // Br emits a single branch instruction and returns the instruction.
  6487  // Not all architectures need the returned instruction, but otherwise
  6488  // the boilerplate is common to all.
  6489  func (s *State) Br(op obj.As, target *ssa.Block) *obj.Prog {
  6490  	p := s.Prog(op)
  6491  	p.To.Type = obj.TYPE_BRANCH
  6492  	s.Branches = append(s.Branches, Branch{P: p, B: target})
  6493  	return p
  6494  }
  6495  
  6496  // DebugFriendlySetPosFrom adjusts Pos.IsStmt subject to heuristics
  6497  // that reduce "jumpy" line number churn when debugging.
  6498  // Spill/fill/copy instructions from the register allocator,
  6499  // phi functions, and instructions with a no-pos position
  6500  // are examples of instructions that can cause churn.
  6501  func (s *State) DebugFriendlySetPosFrom(v *ssa.Value) {
  6502  	switch v.Op {
  6503  	case ssa.OpPhi, ssa.OpCopy, ssa.OpLoadReg, ssa.OpStoreReg:
  6504  		// These are not statements
  6505  		s.SetPos(v.Pos.WithNotStmt())
  6506  	default:
  6507  		p := v.Pos
  6508  		if p != src.NoXPos {
  6509  			// If the position is defined, update the position.
  6510  			// Also convert default IsStmt to NotStmt; only
  6511  			// explicit statement boundaries should appear
  6512  			// in the generated code.
  6513  			if p.IsStmt() != src.PosIsStmt {
  6514  				if s.pp.Pos.IsStmt() == src.PosIsStmt && s.pp.Pos.SameFileAndLine(p) {
  6515  					// If s.pp.Pos already has a statement mark, then it was set here (below) for
  6516  					// the previous value.  If an actual instruction had been emitted for that
  6517  					// value, then the statement mark would have been reset.  Since the statement
  6518  					// mark of s.pp.Pos was not reset, this position (file/line) still needs a
  6519  					// statement mark on an instruction.  If file and line for this value are
  6520  					// the same as the previous value, then the first instruction for this
  6521  					// value will work to take the statement mark.  Return early to avoid
  6522  					// resetting the statement mark.
  6523  					//
  6524  					// The reset of s.pp.Pos occurs in (*Progs).Prog() -- if it emits
  6525  					// an instruction, and the instruction's statement mark was set,
  6526  					// and it is not one of the LosesStmtMark instructions,
  6527  					// then Prog() resets the statement mark on the (*Progs).Pos.
  6528  					return
  6529  				}
  6530  				p = p.WithNotStmt()
  6531  				// Calls use the pos attached to v, but copy the statement mark from State
  6532  			}
  6533  			s.SetPos(p)
  6534  		} else {
  6535  			s.SetPos(s.pp.Pos.WithNotStmt())
  6536  		}
  6537  	}
  6538  }
  6539  
  6540  // emit argument info (locations on stack) for traceback.
  6541  func emitArgInfo(e *ssafn, f *ssa.Func, pp *objw.Progs) {
  6542  	ft := e.curfn.Type()
  6543  	if ft.NumRecvs() == 0 && ft.NumParams() == 0 {
  6544  		return
  6545  	}
  6546  
  6547  	x := EmitArgInfo(e.curfn, f.OwnAux.ABIInfo())
  6548  	x.Set(obj.AttrContentAddressable, true)
  6549  	e.curfn.LSym.Func().ArgInfo = x
  6550  
  6551  	// Emit a funcdata pointing at the arg info data.
  6552  	p := pp.Prog(obj.AFUNCDATA)
  6553  	p.From.SetConst(rtabi.FUNCDATA_ArgInfo)
  6554  	p.To.Type = obj.TYPE_MEM
  6555  	p.To.Name = obj.NAME_EXTERN
  6556  	p.To.Sym = x
  6557  }
  6558  
  6559  // emit argument info (locations on stack) of f for traceback.
  6560  func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
  6561  	x := base.Ctxt.Lookup(fmt.Sprintf("%s.arginfo%d", f.LSym.Name, f.ABI))
  6562  	// NOTE: do not set ContentAddressable here. This may be referenced from
  6563  	// assembly code by name (in this case f is a declaration).
  6564  	// Instead, set it in emitArgInfo above.
  6565  
  6566  	PtrSize := int64(types.PtrSize)
  6567  	uintptrTyp := types.Types[types.TUINTPTR]
  6568  
  6569  	isAggregate := func(t *types.Type) bool {
  6570  		return t.IsStruct() || t.IsArray() || t.IsComplex() || t.IsInterface() || t.IsString() || t.IsSlice()
  6571  	}
  6572  
  6573  	wOff := 0
  6574  	n := 0
  6575  	writebyte := func(o uint8) { wOff = objw.Uint8(x, wOff, o) }
  6576  
  6577  	// Write one non-aggregate arg/field/element.
  6578  	write1 := func(sz, offset int64) {
  6579  		if offset >= rtabi.TraceArgsSpecial {
  6580  			writebyte(rtabi.TraceArgsOffsetTooLarge)
  6581  		} else {
  6582  			writebyte(uint8(offset))
  6583  			writebyte(uint8(sz))
  6584  		}
  6585  		n++
  6586  	}
  6587  
  6588  	// Visit t recursively and write it out.
  6589  	// Returns whether to continue visiting.
  6590  	var visitType func(baseOffset int64, t *types.Type, depth int) bool
  6591  	visitType = func(baseOffset int64, t *types.Type, depth int) bool {
  6592  		if n >= rtabi.TraceArgsLimit {
  6593  			writebyte(rtabi.TraceArgsDotdotdot)
  6594  			return false
  6595  		}
  6596  		if !isAggregate(t) {
  6597  			write1(t.Size(), baseOffset)
  6598  			return true
  6599  		}
  6600  		writebyte(rtabi.TraceArgsStartAgg)
  6601  		depth++
  6602  		if depth >= rtabi.TraceArgsMaxDepth {
  6603  			writebyte(rtabi.TraceArgsDotdotdot)
  6604  			writebyte(rtabi.TraceArgsEndAgg)
  6605  			n++
  6606  			return true
  6607  		}
  6608  		switch {
  6609  		case t.IsInterface(), t.IsString():
  6610  			_ = visitType(baseOffset, uintptrTyp, depth) &&
  6611  				visitType(baseOffset+PtrSize, uintptrTyp, depth)
  6612  		case t.IsSlice():
  6613  			_ = visitType(baseOffset, uintptrTyp, depth) &&
  6614  				visitType(baseOffset+PtrSize, uintptrTyp, depth) &&
  6615  				visitType(baseOffset+PtrSize*2, uintptrTyp, depth)
  6616  		case t.IsComplex():
  6617  			_ = visitType(baseOffset, types.FloatForComplex(t), depth) &&
  6618  				visitType(baseOffset+t.Size()/2, types.FloatForComplex(t), depth)
  6619  		case t.IsArray():
  6620  			if t.NumElem() == 0 {
  6621  				n++ // {} counts as a component
  6622  				break
  6623  			}
  6624  			for i := int64(0); i < t.NumElem(); i++ {
  6625  				if !visitType(baseOffset, t.Elem(), depth) {
  6626  					break
  6627  				}
  6628  				baseOffset += t.Elem().Size()
  6629  			}
  6630  		case t.IsStruct():
  6631  			if t.NumFields() == 0 {
  6632  				n++ // {} counts as a component
  6633  				break
  6634  			}
  6635  			for _, field := range t.Fields() {
  6636  				if !visitType(baseOffset+field.Offset, field.Type, depth) {
  6637  					break
  6638  				}
  6639  			}
  6640  		}
  6641  		writebyte(rtabi.TraceArgsEndAgg)
  6642  		return true
  6643  	}
  6644  
  6645  	start := 0
  6646  	if strings.Contains(f.LSym.Name, "[") {
  6647  		// Skip the dictionary argument - it is implicit and the user doesn't need to see it.
  6648  		start = 1
  6649  	}
  6650  
  6651  	for _, a := range abiInfo.InParams()[start:] {
  6652  		if !visitType(a.FrameOffset(abiInfo), a.Type, 0) {
  6653  			break
  6654  		}
  6655  	}
  6656  	writebyte(rtabi.TraceArgsEndSeq)
  6657  	if wOff > rtabi.TraceArgsMaxLen {
  6658  		base.Fatalf("ArgInfo too large")
  6659  	}
  6660  
  6661  	return x
  6662  }
  6663  
  6664  // for wrapper, emit info of wrapped function.
  6665  func emitWrappedFuncInfo(e *ssafn, pp *objw.Progs) {
  6666  	if base.Ctxt.Flag_linkshared {
  6667  		// Relative reference (SymPtrOff) to another shared object doesn't work.
  6668  		// Unfortunate.
  6669  		return
  6670  	}
  6671  
  6672  	wfn := e.curfn.WrappedFunc
  6673  	if wfn == nil {
  6674  		return
  6675  	}
  6676  
  6677  	wsym := wfn.Linksym()
  6678  	x := base.Ctxt.LookupInit(fmt.Sprintf("%s.wrapinfo", wsym.Name), func(x *obj.LSym) {
  6679  		objw.SymPtrOff(x, 0, wsym)
  6680  		x.Set(obj.AttrContentAddressable, true)
  6681  	})
  6682  	e.curfn.LSym.Func().WrapInfo = x
  6683  
  6684  	// Emit a funcdata pointing at the wrap info data.
  6685  	p := pp.Prog(obj.AFUNCDATA)
  6686  	p.From.SetConst(rtabi.FUNCDATA_WrapInfo)
  6687  	p.To.Type = obj.TYPE_MEM
  6688  	p.To.Name = obj.NAME_EXTERN
  6689  	p.To.Sym = x
  6690  }
  6691  
  6692  // genssa appends entries to pp for each instruction in f.
  6693  func genssa(f *ssa.Func, pp *objw.Progs) {
  6694  	var s State
  6695  	s.ABI = f.OwnAux.Fn.ABI()
  6696  
  6697  	e := f.Frontend().(*ssafn)
  6698  
  6699  	gatherPrintInfo := f.PrintOrHtmlSSA || ssa.GenssaDump[f.Name]
  6700  
  6701  	var lv *liveness.Liveness
  6702  	s.livenessMap, s.partLiveArgs, lv = liveness.Compute(e.curfn, f, e.stkptrsize, pp, gatherPrintInfo)
  6703  	emitArgInfo(e, f, pp)
  6704  	argLiveBlockMap, argLiveValueMap := liveness.ArgLiveness(e.curfn, f, pp)
  6705  
  6706  	openDeferInfo := e.curfn.LSym.Func().OpenCodedDeferInfo
  6707  	if openDeferInfo != nil {
  6708  		// This function uses open-coded defers -- write out the funcdata
  6709  		// info that we computed at the end of genssa.
  6710  		p := pp.Prog(obj.AFUNCDATA)
  6711  		p.From.SetConst(rtabi.FUNCDATA_OpenCodedDeferInfo)
  6712  		p.To.Type = obj.TYPE_MEM
  6713  		p.To.Name = obj.NAME_EXTERN
  6714  		p.To.Sym = openDeferInfo
  6715  	}
  6716  
  6717  	emitWrappedFuncInfo(e, pp)
  6718  
  6719  	// Remember where each block starts.
  6720  	s.bstart = make([]*obj.Prog, f.NumBlocks())
  6721  	s.pp = pp
  6722  	var progToValue map[*obj.Prog]*ssa.Value
  6723  	var progToBlock map[*obj.Prog]*ssa.Block
  6724  	var valueToProgAfter []*obj.Prog // The first Prog following computation of a value v; v is visible at this point.
  6725  	if gatherPrintInfo {
  6726  		progToValue = make(map[*obj.Prog]*ssa.Value, f.NumValues())
  6727  		progToBlock = make(map[*obj.Prog]*ssa.Block, f.NumBlocks())
  6728  		f.Logf("genssa %s\n", f.Name)
  6729  		progToBlock[s.pp.Next] = f.Blocks[0]
  6730  	}
  6731  
  6732  	if base.Ctxt.Flag_locationlists {
  6733  		if cap(f.Cache.ValueToProgAfter) < f.NumValues() {
  6734  			f.Cache.ValueToProgAfter = make([]*obj.Prog, f.NumValues())
  6735  		}
  6736  		valueToProgAfter = f.Cache.ValueToProgAfter[:f.NumValues()]
  6737  		clear(valueToProgAfter)
  6738  	}
  6739  
  6740  	// If the very first instruction is not tagged as a statement,
  6741  	// debuggers may attribute it to previous function in program.
  6742  	firstPos := src.NoXPos
  6743  	for _, v := range f.Entry.Values {
  6744  		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 {
  6745  			firstPos = v.Pos
  6746  			v.Pos = firstPos.WithDefaultStmt()
  6747  			break
  6748  		}
  6749  	}
  6750  
  6751  	// inlMarks has an entry for each Prog that implements an inline mark.
  6752  	// It maps from that Prog to the global inlining id of the inlined body
  6753  	// which should unwind to this Prog's location.
  6754  	var inlMarks map[*obj.Prog]int32
  6755  	var inlMarkList []*obj.Prog
  6756  
  6757  	// inlMarksByPos maps from a (column 1) source position to the set of
  6758  	// Progs that are in the set above and have that source position.
  6759  	var inlMarksByPos map[src.XPos][]*obj.Prog
  6760  
  6761  	var argLiveIdx int = -1 // argument liveness info index
  6762  
  6763  	// These control cache line alignment; if the required portion of
  6764  	// a cache line is not available, then pad to obtain cache line
  6765  	// alignment.  Not implemented on all architectures, may not be
  6766  	// useful on all architectures.
  6767  	var hotAlign, hotRequire int64
  6768  
  6769  	if base.Debug.AlignHot > 0 {
  6770  		switch base.Ctxt.Arch.Name {
  6771  		// enable this on a case-by-case basis, with benchmarking.
  6772  		// currently shown:
  6773  		//   good for amd64
  6774  		//   not helpful for Apple Silicon
  6775  		//
  6776  		case "amd64", "386":
  6777  			// Align to 64 if 31 or fewer bytes remain in a cache line
  6778  			// benchmarks a little better than always aligning, and also
  6779  			// adds slightly less to the (PGO-compiled) binary size.
  6780  			hotAlign = 64
  6781  			hotRequire = 31
  6782  		}
  6783  	}
  6784  
  6785  	// Emit basic blocks
  6786  	for i, b := range f.Blocks {
  6787  
  6788  		s.lineRunStart = nil
  6789  		s.SetPos(s.pp.Pos.WithNotStmt()) // It needs a non-empty Pos, but cannot be a statement boundary (yet).
  6790  
  6791  		if hotAlign > 0 && b.Hotness&ssa.HotPgoInitial == ssa.HotPgoInitial {
  6792  			// So far this has only been shown profitable for PGO-hot loop headers.
  6793  			// The Hotness values allows distinctions between initial blocks that are "hot" or not, and "flow-in" or not.
  6794  			// Currently only the initial blocks of loops are tagged in this way;
  6795  			// there are no blocks tagged "pgo-hot" that are not also tagged "initial".
  6796  			// TODO more heuristics, more architectures.
  6797  			p := s.pp.Prog(obj.APCALIGNMAX)
  6798  			p.From.SetConst(hotAlign)
  6799  			p.To.SetConst(hotRequire)
  6800  		}
  6801  
  6802  		s.bstart[b.ID] = s.pp.Next
  6803  
  6804  		if idx, ok := argLiveBlockMap[b.ID]; ok && idx != argLiveIdx {
  6805  			argLiveIdx = idx
  6806  			p := s.pp.Prog(obj.APCDATA)
  6807  			p.From.SetConst(rtabi.PCDATA_ArgLiveIndex)
  6808  			p.To.SetConst(int64(idx))
  6809  		}
  6810  
  6811  		// Emit values in block
  6812  		Arch.SSAMarkMoves(&s, b)
  6813  		for _, v := range b.Values {
  6814  			x := s.pp.Next
  6815  			s.DebugFriendlySetPosFrom(v)
  6816  
  6817  			if v.Op.ResultInArg0() && v.ResultReg() != v.Args[0].Reg() {
  6818  				v.Fatalf("input[0] and output not in same register %s", v.LongString())
  6819  			}
  6820  
  6821  			switch v.Op {
  6822  			case ssa.OpInitMem:
  6823  				// memory arg needs no code
  6824  			case ssa.OpArg:
  6825  				// input args need no code
  6826  			case ssa.OpSP, ssa.OpSB:
  6827  				// nothing to do
  6828  			case ssa.OpSelect0, ssa.OpSelect1, ssa.OpSelectN, ssa.OpMakeResult:
  6829  				// nothing to do
  6830  			case ssa.OpGetG:
  6831  				// nothing to do when there's a g register,
  6832  				// and checkLower complains if there's not
  6833  			case ssa.OpVarDef, ssa.OpVarLive, ssa.OpKeepAlive, ssa.OpWBend:
  6834  				// nothing to do; already used by liveness
  6835  			case ssa.OpPhi:
  6836  				CheckLoweredPhi(v)
  6837  			case ssa.OpConvert:
  6838  				// nothing to do; no-op conversion for liveness
  6839  				if v.Args[0].Reg() != v.Reg() {
  6840  					v.Fatalf("OpConvert should be a no-op: %s; %s", v.Args[0].LongString(), v.LongString())
  6841  				}
  6842  			case ssa.OpInlMark:
  6843  				p := Arch.Ginsnop(s.pp)
  6844  				if inlMarks == nil {
  6845  					inlMarks = map[*obj.Prog]int32{}
  6846  					inlMarksByPos = map[src.XPos][]*obj.Prog{}
  6847  				}
  6848  				inlMarks[p] = v.AuxInt32()
  6849  				inlMarkList = append(inlMarkList, p)
  6850  				pos := v.Pos.AtColumn1()
  6851  				inlMarksByPos[pos] = append(inlMarksByPos[pos], p)
  6852  				firstPos = src.NoXPos
  6853  
  6854  			default:
  6855  				// Special case for first line in function; move it to the start (which cannot be a register-valued instruction)
  6856  				if firstPos != src.NoXPos && v.Op != ssa.OpArgIntReg && v.Op != ssa.OpArgFloatReg && v.Op != ssa.OpLoadReg && v.Op != ssa.OpStoreReg {
  6857  					s.SetPos(firstPos)
  6858  					firstPos = src.NoXPos
  6859  				}
  6860  				// Attach this safe point to the next
  6861  				// instruction.
  6862  				s.pp.NextLive = s.livenessMap.Get(v)
  6863  				s.pp.NextUnsafe = s.livenessMap.GetUnsafe(v)
  6864  
  6865  				// let the backend handle it
  6866  				Arch.SSAGenValue(&s, v)
  6867  			}
  6868  
  6869  			if idx, ok := argLiveValueMap[v.ID]; ok && idx != argLiveIdx {
  6870  				argLiveIdx = idx
  6871  				p := s.pp.Prog(obj.APCDATA)
  6872  				p.From.SetConst(rtabi.PCDATA_ArgLiveIndex)
  6873  				p.To.SetConst(int64(idx))
  6874  			}
  6875  
  6876  			if base.Ctxt.Flag_locationlists {
  6877  				valueToProgAfter[v.ID] = s.pp.Next
  6878  			}
  6879  
  6880  			if gatherPrintInfo {
  6881  				for ; x != s.pp.Next; x = x.Link {
  6882  					progToValue[x] = v
  6883  				}
  6884  			}
  6885  		}
  6886  		// If this is an empty infinite loop, stick a hardware NOP in there so that debuggers are less confused.
  6887  		if s.bstart[b.ID] == s.pp.Next && len(b.Succs) == 1 && b.Succs[0].Block() == b {
  6888  			p := Arch.Ginsnop(s.pp)
  6889  			p.Pos = p.Pos.WithIsStmt()
  6890  			if b.Pos == src.NoXPos {
  6891  				b.Pos = p.Pos // It needs a file, otherwise a no-file non-zero line causes confusion.  See #35652.
  6892  				if b.Pos == src.NoXPos {
  6893  					b.Pos = s.pp.Text.Pos // Sometimes p.Pos is empty.  See #35695.
  6894  				}
  6895  			}
  6896  			b.Pos = b.Pos.WithBogusLine() // Debuggers are not good about infinite loops, force a change in line number
  6897  		}
  6898  
  6899  		// Set unsafe mark for any end-of-block generated instructions
  6900  		// (normally, conditional or unconditional branches).
  6901  		// This is particularly important for empty blocks, as there
  6902  		// are no values to inherit the unsafe mark from.
  6903  		s.pp.NextUnsafe = s.livenessMap.GetUnsafeBlock(b)
  6904  
  6905  		// Emit control flow instructions for block
  6906  		var next *ssa.Block
  6907  		if i < len(f.Blocks)-1 && base.Flag.N == 0 {
  6908  			// If -N, leave next==nil so every block with successors
  6909  			// ends in a JMP (except call blocks - plive doesn't like
  6910  			// select{send,recv} followed by a JMP call).  Helps keep
  6911  			// line numbers for otherwise empty blocks.
  6912  			next = f.Blocks[i+1]
  6913  		}
  6914  		x := s.pp.Next
  6915  		s.SetPos(b.Pos)
  6916  		Arch.SSAGenBlock(&s, b, next)
  6917  		if gatherPrintInfo {
  6918  			for ; x != s.pp.Next; x = x.Link {
  6919  				progToBlock[x] = b
  6920  			}
  6921  		}
  6922  	}
  6923  	if f.Blocks[len(f.Blocks)-1].Kind == ssa.BlockExit {
  6924  		// We need the return address of a panic call to
  6925  		// still be inside the function in question. So if
  6926  		// it ends in a call which doesn't return, add a
  6927  		// nop (which will never execute) after the call.
  6928  		Arch.Ginsnop(s.pp)
  6929  	}
  6930  	if openDeferInfo != nil {
  6931  		// When doing open-coded defers, generate a disconnected call to
  6932  		// deferreturn and a return. This will be used to during panic
  6933  		// recovery to unwind the stack and return back to the runtime.
  6934  
  6935  		// Note that this exit code doesn't work if a return parameter
  6936  		// is heap-allocated, but open defers aren't enabled in that case.
  6937  
  6938  		// TODO either make this handle heap-allocated return parameters or reuse the other-defers general-purpose code path.
  6939  		s.pp.NextLive = s.livenessMap.DeferReturn
  6940  		p := s.pp.Prog(obj.ACALL)
  6941  		p.To.Type = obj.TYPE_MEM
  6942  		p.To.Name = obj.NAME_EXTERN
  6943  		p.To.Sym = ir.Syms.Deferreturn
  6944  
  6945  		// Load results into registers. So when a deferred function
  6946  		// recovers a panic, it will return to caller with right results.
  6947  		// The results are already in memory, because they are not SSA'd
  6948  		// when the function has defers (see canSSAName).
  6949  		for _, o := range f.OwnAux.ABIInfo().OutParams() {
  6950  			n := o.Name
  6951  			rts, offs := o.RegisterTypesAndOffsets()
  6952  			for i := range o.Registers {
  6953  				Arch.LoadRegResult(&s, f, rts[i], ssa.ObjRegForAbiReg(o.Registers[i], f.Config), n, offs[i])
  6954  			}
  6955  		}
  6956  
  6957  		s.pp.Prog(obj.ARET)
  6958  	}
  6959  
  6960  	if inlMarks != nil {
  6961  		hasCall := false
  6962  
  6963  		// We have some inline marks. Try to find other instructions we're
  6964  		// going to emit anyway, and use those instructions instead of the
  6965  		// inline marks.
  6966  		for p := s.pp.Text; p != nil; p = p.Link {
  6967  			if p.As == obj.ANOP || p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT ||
  6968  				p.As == obj.APCALIGN || p.As == obj.APCALIGNMAX || Arch.LinkArch.Family == sys.Wasm {
  6969  				// Don't use 0-sized instructions as inline marks, because we need
  6970  				// to identify inline mark instructions by pc offset.
  6971  				// (Some of these instructions are sometimes zero-sized, sometimes not.
  6972  				// We must not use anything that even might be zero-sized.)
  6973  				// TODO: are there others?
  6974  				continue
  6975  			}
  6976  			if _, ok := inlMarks[p]; ok {
  6977  				// Don't use inline marks themselves. We don't know
  6978  				// whether they will be zero-sized or not yet.
  6979  				continue
  6980  			}
  6981  			if p.As == obj.ACALL || p.As == obj.ADUFFCOPY || p.As == obj.ADUFFZERO {
  6982  				hasCall = true
  6983  			}
  6984  			pos := p.Pos.AtColumn1()
  6985  			marks := inlMarksByPos[pos]
  6986  			if len(marks) == 0 {
  6987  				continue
  6988  			}
  6989  			for _, m := range marks {
  6990  				// We found an instruction with the same source position as
  6991  				// some of the inline marks.
  6992  				// Use this instruction instead.
  6993  				p.Pos = p.Pos.WithIsStmt() // promote position to a statement
  6994  				s.pp.CurFunc.LSym.Func().AddInlMark(p, inlMarks[m])
  6995  				// Make the inline mark a real nop, so it doesn't generate any code.
  6996  				m.As = obj.ANOP
  6997  				m.Pos = src.NoXPos
  6998  				m.From = obj.Addr{}
  6999  				m.To = obj.Addr{}
  7000  			}
  7001  			delete(inlMarksByPos, pos)
  7002  		}
  7003  		// Any unmatched inline marks now need to be added to the inlining tree (and will generate a nop instruction).
  7004  		for _, p := range inlMarkList {
  7005  			if p.As != obj.ANOP {
  7006  				s.pp.CurFunc.LSym.Func().AddInlMark(p, inlMarks[p])
  7007  			}
  7008  		}
  7009  
  7010  		if e.stksize == 0 && !hasCall {
  7011  			// Frameless leaf function. It doesn't need any preamble,
  7012  			// so make sure its first instruction isn't from an inlined callee.
  7013  			// If it is, add a nop at the start of the function with a position
  7014  			// equal to the start of the function.
  7015  			// This ensures that runtime.FuncForPC(uintptr(reflect.ValueOf(fn).Pointer())).Name()
  7016  			// returns the right answer. See issue 58300.
  7017  			for p := s.pp.Text; p != nil; p = p.Link {
  7018  				if p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT || p.As == obj.ANOP {
  7019  					continue
  7020  				}
  7021  				if base.Ctxt.PosTable.Pos(p.Pos).Base().InliningIndex() >= 0 {
  7022  					// Make a real (not 0-sized) nop.
  7023  					nop := Arch.Ginsnop(s.pp)
  7024  					nop.Pos = e.curfn.Pos().WithIsStmt()
  7025  
  7026  					// Unfortunately, Ginsnop puts the instruction at the
  7027  					// end of the list. Move it up to just before p.
  7028  
  7029  					// Unlink from the current list.
  7030  					for x := s.pp.Text; x != nil; x = x.Link {
  7031  						if x.Link == nop {
  7032  							x.Link = nop.Link
  7033  							break
  7034  						}
  7035  					}
  7036  					// Splice in right before p.
  7037  					for x := s.pp.Text; x != nil; x = x.Link {
  7038  						if x.Link == p {
  7039  							nop.Link = p
  7040  							x.Link = nop
  7041  							break
  7042  						}
  7043  					}
  7044  				}
  7045  				break
  7046  			}
  7047  		}
  7048  	}
  7049  
  7050  	if base.Ctxt.Flag_locationlists {
  7051  		var debugInfo *ssa.FuncDebug
  7052  		debugInfo = e.curfn.DebugInfo.(*ssa.FuncDebug)
  7053  		// Save off entry ID in case we need it later for DWARF generation
  7054  		// for return values promoted to the heap.
  7055  		debugInfo.EntryID = f.Entry.ID
  7056  		if e.curfn.ABI == obj.ABIInternal && base.Flag.N != 0 {
  7057  			ssa.BuildFuncDebugNoOptimized(base.Ctxt, f, base.Debug.LocationLists > 1, StackOffset, debugInfo)
  7058  		} else {
  7059  			ssa.BuildFuncDebug(base.Ctxt, f, base.Debug.LocationLists, StackOffset, debugInfo)
  7060  		}
  7061  		bstart := s.bstart
  7062  		idToIdx := make([]int, f.NumBlocks())
  7063  		for i, b := range f.Blocks {
  7064  			idToIdx[b.ID] = i
  7065  		}
  7066  		// Register a callback that will be used later to fill in PCs into location
  7067  		// lists. At the moment, Prog.Pc is a sequence number; it's not a real PC
  7068  		// until after assembly, so the translation needs to be deferred.
  7069  		debugInfo.GetPC = func(b, v ssa.ID) int64 {
  7070  			switch v {
  7071  			case ssa.BlockStart.ID:
  7072  				if b == f.Entry.ID {
  7073  					return 0 // Start at the very beginning, at the assembler-generated prologue.
  7074  					// this should only happen for function args (ssa.OpArg)
  7075  				}
  7076  				return bstart[b].Pc
  7077  			case ssa.BlockEnd.ID:
  7078  				blk := f.Blocks[idToIdx[b]]
  7079  				nv := len(blk.Values)
  7080  				return valueToProgAfter[blk.Values[nv-1].ID].Pc
  7081  			case ssa.FuncEnd.ID:
  7082  				return e.curfn.LSym.Size
  7083  			default:
  7084  				return valueToProgAfter[v].Pc
  7085  			}
  7086  		}
  7087  	}
  7088  
  7089  	// Resolve branches, and relax DefaultStmt into NotStmt
  7090  	for _, br := range s.Branches {
  7091  		br.P.To.SetTarget(s.bstart[br.B.ID])
  7092  		if br.P.Pos.IsStmt() != src.PosIsStmt {
  7093  			br.P.Pos = br.P.Pos.WithNotStmt()
  7094  		} else if v0 := br.B.FirstPossibleStmtValue(); v0 != nil && v0.Pos.Line() == br.P.Pos.Line() && v0.Pos.IsStmt() == src.PosIsStmt {
  7095  			br.P.Pos = br.P.Pos.WithNotStmt()
  7096  		}
  7097  
  7098  	}
  7099  
  7100  	// Resolve jump table destinations.
  7101  	for _, jt := range s.JumpTables {
  7102  		// Convert from *Block targets to *Prog targets.
  7103  		targets := make([]*obj.Prog, len(jt.Succs))
  7104  		for i, e := range jt.Succs {
  7105  			targets[i] = s.bstart[e.Block().ID]
  7106  		}
  7107  		// Add to list of jump tables to be resolved at assembly time.
  7108  		// The assembler converts from *Prog entries to absolute addresses
  7109  		// once it knows instruction byte offsets.
  7110  		fi := s.pp.CurFunc.LSym.Func()
  7111  		fi.JumpTables = append(fi.JumpTables, obj.JumpTable{Sym: jt.Aux.(*obj.LSym), Targets: targets})
  7112  	}
  7113  
  7114  	if e.log { // spew to stdout
  7115  		filename := ""
  7116  		for p := s.pp.Text; p != nil; p = p.Link {
  7117  			if p.Pos.IsKnown() && p.InnermostFilename() != filename {
  7118  				filename = p.InnermostFilename()
  7119  				f.Logf("# %s\n", filename)
  7120  			}
  7121  
  7122  			var s string
  7123  			if v, ok := progToValue[p]; ok {
  7124  				s = v.String()
  7125  			} else if b, ok := progToBlock[p]; ok {
  7126  				s = b.String()
  7127  			} else {
  7128  				s = "   " // most value and branch strings are 2-3 characters long
  7129  			}
  7130  			f.Logf(" %-6s\t%.5d (%s)\t%s\n", s, p.Pc, p.InnermostLineNumber(), p.InstructionString())
  7131  		}
  7132  	}
  7133  	if f.HTMLWriter != nil { // spew to ssa.html
  7134  		var buf strings.Builder
  7135  		buf.WriteString("<code>")
  7136  		buf.WriteString("<dl class=\"ssa-gen\">")
  7137  		filename := ""
  7138  
  7139  		liveness := lv.Format(nil)
  7140  		if liveness != "" {
  7141  			buf.WriteString("<dt class=\"ssa-prog-src\"></dt><dd class=\"ssa-prog\">")
  7142  			buf.WriteString(html.EscapeString("# " + liveness))
  7143  			buf.WriteString("</dd>")
  7144  		}
  7145  
  7146  		for p := s.pp.Text; p != nil; p = p.Link {
  7147  			// Don't spam every line with the file name, which is often huge.
  7148  			// Only print changes, and "unknown" is not a change.
  7149  			if p.Pos.IsKnown() && p.InnermostFilename() != filename {
  7150  				filename = p.InnermostFilename()
  7151  				buf.WriteString("<dt class=\"ssa-prog-src\"></dt><dd class=\"ssa-prog\">")
  7152  				buf.WriteString(html.EscapeString("# " + filename))
  7153  				buf.WriteString("</dd>")
  7154  			}
  7155  
  7156  			buf.WriteString("<dt class=\"ssa-prog-src\">")
  7157  			if v, ok := progToValue[p]; ok {
  7158  
  7159  				// Prefix calls with their liveness, if any
  7160  				if p.As != obj.APCDATA {
  7161  					if liveness := lv.Format(v); liveness != "" {
  7162  						// Steal this line, and restart a line
  7163  						buf.WriteString("</dt><dd class=\"ssa-prog\">")
  7164  						buf.WriteString(html.EscapeString("# " + liveness))
  7165  						buf.WriteString("</dd>")
  7166  						// restarting a line
  7167  						buf.WriteString("<dt class=\"ssa-prog-src\">")
  7168  					}
  7169  				}
  7170  
  7171  				buf.WriteString(v.HTML())
  7172  			} else if b, ok := progToBlock[p]; ok {
  7173  				buf.WriteString("<b>" + b.HTML() + "</b>")
  7174  			}
  7175  			buf.WriteString("</dt>")
  7176  			buf.WriteString("<dd class=\"ssa-prog\">")
  7177  			fmt.Fprintf(&buf, "%.5d <span class=\"l%v line-number\">(%s)</span> %s", p.Pc, p.InnermostLineNumber(), p.InnermostLineNumberHTML(), html.EscapeString(p.InstructionString()))
  7178  			buf.WriteString("</dd>")
  7179  		}
  7180  		buf.WriteString("</dl>")
  7181  		buf.WriteString("</code>")
  7182  		f.HTMLWriter.WriteColumn("genssa", "genssa", "ssa-prog", buf.String())
  7183  	}
  7184  	if ssa.GenssaDump[f.Name] {
  7185  		fi := f.DumpFileForPhase("genssa")
  7186  		if fi != nil {
  7187  
  7188  			// inliningDiffers if any filename changes or if any line number except the innermost (last index) changes.
  7189  			inliningDiffers := func(a, b []src.Pos) bool {
  7190  				if len(a) != len(b) {
  7191  					return true
  7192  				}
  7193  				for i := range a {
  7194  					if a[i].Filename() != b[i].Filename() {
  7195  						return true
  7196  					}
  7197  					if i != len(a)-1 && a[i].Line() != b[i].Line() {
  7198  						return true
  7199  					}
  7200  				}
  7201  				return false
  7202  			}
  7203  
  7204  			var allPosOld []src.Pos
  7205  			var allPos []src.Pos
  7206  
  7207  			for p := s.pp.Text; p != nil; p = p.Link {
  7208  				if p.Pos.IsKnown() {
  7209  					allPos = allPos[:0]
  7210  					p.Ctxt.AllPos(p.Pos, func(pos src.Pos) { allPos = append(allPos, pos) })
  7211  					if inliningDiffers(allPos, allPosOld) {
  7212  						for _, pos := range allPos {
  7213  							fmt.Fprintf(fi, "# %s:%d\n", pos.Filename(), pos.Line())
  7214  						}
  7215  						allPos, allPosOld = allPosOld, allPos // swap, not copy, so that they do not share slice storage.
  7216  					}
  7217  				}
  7218  
  7219  				var s string
  7220  				if v, ok := progToValue[p]; ok {
  7221  					s = v.String()
  7222  				} else if b, ok := progToBlock[p]; ok {
  7223  					s = b.String()
  7224  				} else {
  7225  					s = "   " // most value and branch strings are 2-3 characters long
  7226  				}
  7227  				fmt.Fprintf(fi, " %-6s\t%.5d %s\t%s\n", s, p.Pc, ssa.StmtString(p.Pos), p.InstructionString())
  7228  			}
  7229  			fi.Close()
  7230  		}
  7231  	}
  7232  
  7233  	defframe(&s, e, f)
  7234  
  7235  	f.HTMLWriter.Close()
  7236  	f.HTMLWriter = nil
  7237  }
  7238  
  7239  func defframe(s *State, e *ssafn, f *ssa.Func) {
  7240  	pp := s.pp
  7241  
  7242  	s.maxarg = types.RoundUp(s.maxarg, e.stkalign)
  7243  	frame := s.maxarg + e.stksize
  7244  	if Arch.PadFrame != nil {
  7245  		frame = Arch.PadFrame(frame)
  7246  	}
  7247  
  7248  	// Fill in argument and frame size.
  7249  	pp.Text.To.Type = obj.TYPE_TEXTSIZE
  7250  	pp.Text.To.Val = int32(types.RoundUp(f.OwnAux.ArgWidth(), int64(types.RegSize)))
  7251  	pp.Text.To.Offset = frame
  7252  
  7253  	p := pp.Text
  7254  
  7255  	// Insert code to spill argument registers if the named slot may be partially
  7256  	// live. That is, the named slot is considered live by liveness analysis,
  7257  	// (because a part of it is live), but we may not spill all parts into the
  7258  	// slot. This can only happen with aggregate-typed arguments that are SSA-able
  7259  	// and not address-taken (for non-SSA-able or address-taken arguments we always
  7260  	// spill upfront).
  7261  	// Note: spilling is unnecessary in the -N/no-optimize case, since all values
  7262  	// will be considered non-SSAable and spilled up front.
  7263  	// TODO(register args) Make liveness more fine-grained to that partial spilling is okay.
  7264  	if f.OwnAux.ABIInfo().InRegistersUsed() != 0 && base.Flag.N == 0 {
  7265  		// First, see if it is already spilled before it may be live. Look for a spill
  7266  		// in the entry block up to the first safepoint.
  7267  		type nameOff struct {
  7268  			n   *ir.Name
  7269  			off int64
  7270  		}
  7271  		partLiveArgsSpilled := make(map[nameOff]bool)
  7272  		for _, v := range f.Entry.Values {
  7273  			if v.Op.IsCall() {
  7274  				break
  7275  			}
  7276  			if v.Op != ssa.OpStoreReg || v.Args[0].Op != ssa.OpArgIntReg {
  7277  				continue
  7278  			}
  7279  			n, off := ssa.AutoVar(v)
  7280  			if n.Class != ir.PPARAM || n.Addrtaken() || !ssa.CanSSA(n.Type()) || !s.partLiveArgs[n] {
  7281  				continue
  7282  			}
  7283  			partLiveArgsSpilled[nameOff{n, off}] = true
  7284  		}
  7285  
  7286  		// Then, insert code to spill registers if not already.
  7287  		for _, a := range f.OwnAux.ABIInfo().InParams() {
  7288  			n := a.Name
  7289  			if n == nil || n.Addrtaken() || !ssa.CanSSA(n.Type()) || !s.partLiveArgs[n] || len(a.Registers) <= 1 {
  7290  				continue
  7291  			}
  7292  			rts, offs := a.RegisterTypesAndOffsets()
  7293  			for i := range a.Registers {
  7294  				if !rts[i].HasPointers() {
  7295  					continue
  7296  				}
  7297  				if partLiveArgsSpilled[nameOff{n, offs[i]}] {
  7298  					continue // already spilled
  7299  				}
  7300  				reg := ssa.ObjRegForAbiReg(a.Registers[i], f.Config)
  7301  				p = Arch.SpillArgReg(pp, p, f, rts[i], reg, n, offs[i])
  7302  			}
  7303  		}
  7304  	}
  7305  
  7306  	// Insert code to zero ambiguously live variables so that the
  7307  	// garbage collector only sees initialized values when it
  7308  	// looks for pointers.
  7309  	var lo, hi int64
  7310  
  7311  	// Opaque state for backend to use. Current backends use it to
  7312  	// keep track of which helper registers have been zeroed.
  7313  	var state uint32
  7314  
  7315  	// Iterate through declarations. Autos are sorted in decreasing
  7316  	// frame offset order.
  7317  	for _, n := range e.curfn.Dcl {
  7318  		if !n.Needzero() {
  7319  			continue
  7320  		}
  7321  		if n.Class != ir.PAUTO {
  7322  			e.Fatalf(n.Pos(), "needzero class %d", n.Class)
  7323  		}
  7324  		if n.Type().Size()%int64(types.PtrSize) != 0 || n.FrameOffset()%int64(types.PtrSize) != 0 || n.Type().Size() == 0 {
  7325  			e.Fatalf(n.Pos(), "var %L has size %d offset %d", n, n.Type().Size(), n.Offset_)
  7326  		}
  7327  
  7328  		if lo != hi && n.FrameOffset()+n.Type().Size() >= lo-int64(2*types.RegSize) {
  7329  			// Merge with range we already have.
  7330  			lo = n.FrameOffset()
  7331  			continue
  7332  		}
  7333  
  7334  		// Zero old range
  7335  		p = Arch.ZeroRange(pp, p, frame+lo, hi-lo, &state)
  7336  
  7337  		// Set new range.
  7338  		lo = n.FrameOffset()
  7339  		hi = lo + n.Type().Size()
  7340  	}
  7341  
  7342  	// Zero final range.
  7343  	Arch.ZeroRange(pp, p, frame+lo, hi-lo, &state)
  7344  }
  7345  
  7346  // For generating consecutive jump instructions to model a specific branching
  7347  type IndexJump struct {
  7348  	Jump  obj.As
  7349  	Index int
  7350  }
  7351  
  7352  func (s *State) oneJump(b *ssa.Block, jump *IndexJump) {
  7353  	p := s.Br(jump.Jump, b.Succs[jump.Index].Block())
  7354  	p.Pos = b.Pos
  7355  }
  7356  
  7357  // CombJump generates combinational instructions (2 at present) for a block jump,
  7358  // thereby the behaviour of non-standard condition codes could be simulated
  7359  func (s *State) CombJump(b, next *ssa.Block, jumps *[2][2]IndexJump) {
  7360  	switch next {
  7361  	case b.Succs[0].Block():
  7362  		s.oneJump(b, &jumps[0][0])
  7363  		s.oneJump(b, &jumps[0][1])
  7364  	case b.Succs[1].Block():
  7365  		s.oneJump(b, &jumps[1][0])
  7366  		s.oneJump(b, &jumps[1][1])
  7367  	default:
  7368  		var q *obj.Prog
  7369  		if b.Likely != ssa.BranchUnlikely {
  7370  			s.oneJump(b, &jumps[1][0])
  7371  			s.oneJump(b, &jumps[1][1])
  7372  			q = s.Br(obj.AJMP, b.Succs[1].Block())
  7373  		} else {
  7374  			s.oneJump(b, &jumps[0][0])
  7375  			s.oneJump(b, &jumps[0][1])
  7376  			q = s.Br(obj.AJMP, b.Succs[0].Block())
  7377  		}
  7378  		q.Pos = b.Pos
  7379  	}
  7380  }
  7381  
  7382  // AddAux adds the offset in the aux fields (AuxInt and Aux) of v to a.
  7383  func AddAux(a *obj.Addr, v *ssa.Value) {
  7384  	AddAux2(a, v, v.AuxInt)
  7385  }
  7386  func AddAux2(a *obj.Addr, v *ssa.Value, offset int64) {
  7387  	if a.Type != obj.TYPE_MEM && a.Type != obj.TYPE_ADDR {
  7388  		v.Fatalf("bad AddAux addr %v", a)
  7389  	}
  7390  	// add integer offset
  7391  	a.Offset += offset
  7392  
  7393  	// If no additional symbol offset, we're done.
  7394  	if v.Aux == nil {
  7395  		return
  7396  	}
  7397  	// Add symbol's offset from its base register.
  7398  	switch n := v.Aux.(type) {
  7399  	case *ssa.AuxCall:
  7400  		a.Name = obj.NAME_EXTERN
  7401  		a.Sym = n.Fn
  7402  	case *obj.LSym:
  7403  		a.Name = obj.NAME_EXTERN
  7404  		a.Sym = n
  7405  	case *ir.Name:
  7406  		if n.Class == ir.PPARAM || (n.Class == ir.PPARAMOUT && !n.IsOutputParamInRegisters()) {
  7407  			a.Name = obj.NAME_PARAM
  7408  		} else {
  7409  			a.Name = obj.NAME_AUTO
  7410  		}
  7411  		a.Sym = n.Linksym()
  7412  		a.Offset += n.FrameOffset()
  7413  	default:
  7414  		v.Fatalf("aux in %s not implemented %#v", v, v.Aux)
  7415  	}
  7416  }
  7417  
  7418  // extendIndex extends v to a full int width.
  7419  // panic with the given kind if v does not fit in an int (only on 32-bit archs).
  7420  func (s *state) extendIndex(idx, len *ssa.Value, kind ssa.BoundsKind, bounded bool) *ssa.Value {
  7421  	size := idx.Type.Size()
  7422  	if size == s.config.PtrSize {
  7423  		return idx
  7424  	}
  7425  	if size > s.config.PtrSize {
  7426  		// truncate 64-bit indexes on 32-bit pointer archs. Test the
  7427  		// high word and branch to out-of-bounds failure if it is not 0.
  7428  		var lo *ssa.Value
  7429  		if idx.Type.IsSigned() {
  7430  			lo = s.newValue1(ssa.OpInt64Lo, types.Types[types.TINT], idx)
  7431  		} else {
  7432  			lo = s.newValue1(ssa.OpInt64Lo, types.Types[types.TUINT], idx)
  7433  		}
  7434  		if bounded || base.Flag.B != 0 {
  7435  			return lo
  7436  		}
  7437  		bNext := s.f.NewBlock(ssa.BlockPlain)
  7438  		bPanic := s.f.NewBlock(ssa.BlockExit)
  7439  		hi := s.newValue1(ssa.OpInt64Hi, types.Types[types.TUINT32], idx)
  7440  		cmp := s.newValue2(ssa.OpEq32, types.Types[types.TBOOL], hi, s.constInt32(types.Types[types.TUINT32], 0))
  7441  		if !idx.Type.IsSigned() {
  7442  			switch kind {
  7443  			case ssa.BoundsIndex:
  7444  				kind = ssa.BoundsIndexU
  7445  			case ssa.BoundsSliceAlen:
  7446  				kind = ssa.BoundsSliceAlenU
  7447  			case ssa.BoundsSliceAcap:
  7448  				kind = ssa.BoundsSliceAcapU
  7449  			case ssa.BoundsSliceB:
  7450  				kind = ssa.BoundsSliceBU
  7451  			case ssa.BoundsSlice3Alen:
  7452  				kind = ssa.BoundsSlice3AlenU
  7453  			case ssa.BoundsSlice3Acap:
  7454  				kind = ssa.BoundsSlice3AcapU
  7455  			case ssa.BoundsSlice3B:
  7456  				kind = ssa.BoundsSlice3BU
  7457  			case ssa.BoundsSlice3C:
  7458  				kind = ssa.BoundsSlice3CU
  7459  			}
  7460  		}
  7461  		b := s.endBlock()
  7462  		b.Kind = ssa.BlockIf
  7463  		b.SetControl(cmp)
  7464  		b.Likely = ssa.BranchLikely
  7465  		b.AddEdgeTo(bNext)
  7466  		b.AddEdgeTo(bPanic)
  7467  
  7468  		s.startBlock(bPanic)
  7469  		mem := s.newValue4I(ssa.OpPanicExtend, types.TypeMem, int64(kind), hi, lo, len, s.mem())
  7470  		s.endBlock().SetControl(mem)
  7471  		s.startBlock(bNext)
  7472  
  7473  		return lo
  7474  	}
  7475  
  7476  	// Extend value to the required size
  7477  	var op ssa.Op
  7478  	if idx.Type.IsSigned() {
  7479  		switch 10*size + s.config.PtrSize {
  7480  		case 14:
  7481  			op = ssa.OpSignExt8to32
  7482  		case 18:
  7483  			op = ssa.OpSignExt8to64
  7484  		case 24:
  7485  			op = ssa.OpSignExt16to32
  7486  		case 28:
  7487  			op = ssa.OpSignExt16to64
  7488  		case 48:
  7489  			op = ssa.OpSignExt32to64
  7490  		default:
  7491  			s.Fatalf("bad signed index extension %s", idx.Type)
  7492  		}
  7493  	} else {
  7494  		switch 10*size + s.config.PtrSize {
  7495  		case 14:
  7496  			op = ssa.OpZeroExt8to32
  7497  		case 18:
  7498  			op = ssa.OpZeroExt8to64
  7499  		case 24:
  7500  			op = ssa.OpZeroExt16to32
  7501  		case 28:
  7502  			op = ssa.OpZeroExt16to64
  7503  		case 48:
  7504  			op = ssa.OpZeroExt32to64
  7505  		default:
  7506  			s.Fatalf("bad unsigned index extension %s", idx.Type)
  7507  		}
  7508  	}
  7509  	return s.newValue1(op, types.Types[types.TINT], idx)
  7510  }
  7511  
  7512  // CheckLoweredPhi checks that regalloc and stackalloc correctly handled phi values.
  7513  // Called during ssaGenValue.
  7514  func CheckLoweredPhi(v *ssa.Value) {
  7515  	if v.Op != ssa.OpPhi {
  7516  		v.Fatalf("CheckLoweredPhi called with non-phi value: %v", v.LongString())
  7517  	}
  7518  	if v.Type.IsMemory() {
  7519  		return
  7520  	}
  7521  	f := v.Block.Func
  7522  	loc := f.RegAlloc[v.ID]
  7523  	for _, a := range v.Args {
  7524  		if aloc := f.RegAlloc[a.ID]; aloc != loc { // TODO: .Equal() instead?
  7525  			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)
  7526  		}
  7527  	}
  7528  }
  7529  
  7530  // CheckLoweredGetClosurePtr checks that v is the first instruction in the function's entry block,
  7531  // except for incoming in-register arguments.
  7532  // The output of LoweredGetClosurePtr is generally hardwired to the correct register.
  7533  // That register contains the closure pointer on closure entry.
  7534  func CheckLoweredGetClosurePtr(v *ssa.Value) {
  7535  	entry := v.Block.Func.Entry
  7536  	if entry != v.Block {
  7537  		base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
  7538  	}
  7539  	for _, w := range entry.Values {
  7540  		if w == v {
  7541  			break
  7542  		}
  7543  		switch w.Op {
  7544  		case ssa.OpArgIntReg, ssa.OpArgFloatReg:
  7545  			// okay
  7546  		default:
  7547  			base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
  7548  		}
  7549  	}
  7550  }
  7551  
  7552  // CheckArgReg ensures that v is in the function's entry block.
  7553  func CheckArgReg(v *ssa.Value) {
  7554  	entry := v.Block.Func.Entry
  7555  	if entry != v.Block {
  7556  		base.Fatalf("in %s, badly placed ArgIReg or ArgFReg: %v %v", v.Block.Func.Name, v.Block, v)
  7557  	}
  7558  }
  7559  
  7560  func AddrAuto(a *obj.Addr, v *ssa.Value) {
  7561  	n, off := ssa.AutoVar(v)
  7562  	a.Type = obj.TYPE_MEM
  7563  	a.Sym = n.Linksym()
  7564  	a.Reg = int16(Arch.REGSP)
  7565  	a.Offset = n.FrameOffset() + off
  7566  	if n.Class == ir.PPARAM || (n.Class == ir.PPARAMOUT && !n.IsOutputParamInRegisters()) {
  7567  		a.Name = obj.NAME_PARAM
  7568  	} else {
  7569  		a.Name = obj.NAME_AUTO
  7570  	}
  7571  }
  7572  
  7573  // Call returns a new CALL instruction for the SSA value v.
  7574  // It uses PrepareCall to prepare the call.
  7575  func (s *State) Call(v *ssa.Value) *obj.Prog {
  7576  	pPosIsStmt := s.pp.Pos.IsStmt() // The statement-ness fo the call comes from ssaGenState
  7577  	s.PrepareCall(v)
  7578  
  7579  	p := s.Prog(obj.ACALL)
  7580  	if pPosIsStmt == src.PosIsStmt {
  7581  		p.Pos = v.Pos.WithIsStmt()
  7582  	} else {
  7583  		p.Pos = v.Pos.WithNotStmt()
  7584  	}
  7585  	if sym, ok := v.Aux.(*ssa.AuxCall); ok && sym.Fn != nil {
  7586  		p.To.Type = obj.TYPE_MEM
  7587  		p.To.Name = obj.NAME_EXTERN
  7588  		p.To.Sym = sym.Fn
  7589  	} else {
  7590  		// TODO(mdempsky): Can these differences be eliminated?
  7591  		switch Arch.LinkArch.Family {
  7592  		case sys.AMD64, sys.I386, sys.PPC64, sys.RISCV64, sys.S390X, sys.Wasm:
  7593  			p.To.Type = obj.TYPE_REG
  7594  		case sys.ARM, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64:
  7595  			p.To.Type = obj.TYPE_MEM
  7596  		default:
  7597  			base.Fatalf("unknown indirect call family")
  7598  		}
  7599  		p.To.Reg = v.Args[0].Reg()
  7600  	}
  7601  	return p
  7602  }
  7603  
  7604  // TailCall returns a new tail call instruction for the SSA value v.
  7605  // It is like Call, but for a tail call.
  7606  func (s *State) TailCall(v *ssa.Value) *obj.Prog {
  7607  	p := s.Call(v)
  7608  	p.As = obj.ARET
  7609  	return p
  7610  }
  7611  
  7612  // PrepareCall prepares to emit a CALL instruction for v and does call-related bookkeeping.
  7613  // It must be called immediately before emitting the actual CALL instruction,
  7614  // since it emits PCDATA for the stack map at the call (calls are safe points).
  7615  func (s *State) PrepareCall(v *ssa.Value) {
  7616  	idx := s.livenessMap.Get(v)
  7617  	if !idx.StackMapValid() {
  7618  		// See Liveness.hasStackMap.
  7619  		if sym, ok := v.Aux.(*ssa.AuxCall); !ok || !(sym.Fn == ir.Syms.WBZero || sym.Fn == ir.Syms.WBMove) {
  7620  			base.Fatalf("missing stack map index for %v", v.LongString())
  7621  		}
  7622  	}
  7623  
  7624  	call, ok := v.Aux.(*ssa.AuxCall)
  7625  
  7626  	if ok {
  7627  		// Record call graph information for nowritebarrierrec
  7628  		// analysis.
  7629  		if nowritebarrierrecCheck != nil {
  7630  			nowritebarrierrecCheck.recordCall(s.pp.CurFunc, call.Fn, v.Pos)
  7631  		}
  7632  	}
  7633  
  7634  	if s.maxarg < v.AuxInt {
  7635  		s.maxarg = v.AuxInt
  7636  	}
  7637  }
  7638  
  7639  // UseArgs records the fact that an instruction needs a certain amount of
  7640  // callee args space for its use.
  7641  func (s *State) UseArgs(n int64) {
  7642  	if s.maxarg < n {
  7643  		s.maxarg = n
  7644  	}
  7645  }
  7646  
  7647  // fieldIdx finds the index of the field referred to by the ODOT node n.
  7648  func fieldIdx(n *ir.SelectorExpr) int {
  7649  	t := n.X.Type()
  7650  	if !t.IsStruct() {
  7651  		panic("ODOT's LHS is not a struct")
  7652  	}
  7653  
  7654  	for i, f := range t.Fields() {
  7655  		if f.Sym == n.Sel {
  7656  			if f.Offset != n.Offset() {
  7657  				panic("field offset doesn't match")
  7658  			}
  7659  			return i
  7660  		}
  7661  	}
  7662  	panic(fmt.Sprintf("can't find field in expr %v\n", n))
  7663  
  7664  	// TODO: keep the result of this function somewhere in the ODOT Node
  7665  	// so we don't have to recompute it each time we need it.
  7666  }
  7667  
  7668  // ssafn holds frontend information about a function that the backend is processing.
  7669  // It also exports a bunch of compiler services for the ssa backend.
  7670  type ssafn struct {
  7671  	curfn      *ir.Func
  7672  	strings    map[string]*obj.LSym // map from constant string to data symbols
  7673  	stksize    int64                // stack size for current frame
  7674  	stkptrsize int64                // prefix of stack containing pointers
  7675  
  7676  	// alignment for current frame.
  7677  	// NOTE: when stkalign > PtrSize, currently this only ensures the offsets of
  7678  	// objects in the stack frame are aligned. The stack pointer is still aligned
  7679  	// only PtrSize.
  7680  	stkalign int64
  7681  
  7682  	log bool // print ssa debug to the stdout
  7683  }
  7684  
  7685  // StringData returns a symbol which
  7686  // is the data component of a global string constant containing s.
  7687  func (e *ssafn) StringData(s string) *obj.LSym {
  7688  	if aux, ok := e.strings[s]; ok {
  7689  		return aux
  7690  	}
  7691  	if e.strings == nil {
  7692  		e.strings = make(map[string]*obj.LSym)
  7693  	}
  7694  	data := staticdata.StringSym(e.curfn.Pos(), s)
  7695  	e.strings[s] = data
  7696  	return data
  7697  }
  7698  
  7699  // SplitSlot returns a slot representing the data of parent starting at offset.
  7700  func (e *ssafn) SplitSlot(parent *ssa.LocalSlot, suffix string, offset int64, t *types.Type) ssa.LocalSlot {
  7701  	node := parent.N
  7702  
  7703  	if node.Class != ir.PAUTO || node.Addrtaken() {
  7704  		// addressed things and non-autos retain their parents (i.e., cannot truly be split)
  7705  		return ssa.LocalSlot{N: node, Type: t, Off: parent.Off + offset}
  7706  	}
  7707  
  7708  	sym := &types.Sym{Name: node.Sym().Name + suffix, Pkg: types.LocalPkg}
  7709  	n := e.curfn.NewLocal(parent.N.Pos(), sym, t)
  7710  	n.SetUsed(true)
  7711  	n.SetEsc(ir.EscNever)
  7712  	types.CalcSize(t)
  7713  	return ssa.LocalSlot{N: n, Type: t, Off: 0, SplitOf: parent, SplitOffset: offset}
  7714  }
  7715  
  7716  // Logf logs a message from the compiler.
  7717  func (e *ssafn) Logf(msg string, args ...interface{}) {
  7718  	if e.log {
  7719  		fmt.Printf(msg, args...)
  7720  	}
  7721  }
  7722  
  7723  func (e *ssafn) Log() bool {
  7724  	return e.log
  7725  }
  7726  
  7727  // Fatalf reports a compiler error and exits.
  7728  func (e *ssafn) Fatalf(pos src.XPos, msg string, args ...interface{}) {
  7729  	base.Pos = pos
  7730  	nargs := append([]interface{}{ir.FuncName(e.curfn)}, args...)
  7731  	base.Fatalf("'%s': "+msg, nargs...)
  7732  }
  7733  
  7734  // Warnl reports a "warning", which is usually flag-triggered
  7735  // logging output for the benefit of tests.
  7736  func (e *ssafn) Warnl(pos src.XPos, fmt_ string, args ...interface{}) {
  7737  	base.WarnfAt(pos, fmt_, args...)
  7738  }
  7739  
  7740  func (e *ssafn) Debug_checknil() bool {
  7741  	return base.Debug.Nil != 0
  7742  }
  7743  
  7744  func (e *ssafn) UseWriteBarrier() bool {
  7745  	return base.Flag.WB
  7746  }
  7747  
  7748  func (e *ssafn) Syslook(name string) *obj.LSym {
  7749  	switch name {
  7750  	case "goschedguarded":
  7751  		return ir.Syms.Goschedguarded
  7752  	case "writeBarrier":
  7753  		return ir.Syms.WriteBarrier
  7754  	case "wbZero":
  7755  		return ir.Syms.WBZero
  7756  	case "wbMove":
  7757  		return ir.Syms.WBMove
  7758  	case "cgoCheckMemmove":
  7759  		return ir.Syms.CgoCheckMemmove
  7760  	case "cgoCheckPtrWrite":
  7761  		return ir.Syms.CgoCheckPtrWrite
  7762  	}
  7763  	e.Fatalf(src.NoXPos, "unknown Syslook func %v", name)
  7764  	return nil
  7765  }
  7766  
  7767  func (e *ssafn) Func() *ir.Func {
  7768  	return e.curfn
  7769  }
  7770  
  7771  func clobberBase(n ir.Node) ir.Node {
  7772  	if n.Op() == ir.ODOT {
  7773  		n := n.(*ir.SelectorExpr)
  7774  		if n.X.Type().NumFields() == 1 {
  7775  			return clobberBase(n.X)
  7776  		}
  7777  	}
  7778  	if n.Op() == ir.OINDEX {
  7779  		n := n.(*ir.IndexExpr)
  7780  		if n.X.Type().IsArray() && n.X.Type().NumElem() == 1 {
  7781  			return clobberBase(n.X)
  7782  		}
  7783  	}
  7784  	return n
  7785  }
  7786  
  7787  // callTargetLSym returns the correct LSym to call 'callee' using its ABI.
  7788  func callTargetLSym(callee *ir.Name) *obj.LSym {
  7789  	if callee.Func == nil {
  7790  		// TODO(austin): This happens in case of interface method I.M from imported package.
  7791  		// It's ABIInternal, and would be better if callee.Func was never nil and we didn't
  7792  		// need this case.
  7793  		return callee.Linksym()
  7794  	}
  7795  
  7796  	return callee.LinksymABI(callee.Func.ABI)
  7797  }
  7798  
  7799  // deferStructFnField is the field index of _defer.fn.
  7800  const deferStructFnField = 4
  7801  
  7802  var deferType *types.Type
  7803  
  7804  // deferstruct returns a type interchangeable with runtime._defer.
  7805  // Make sure this stays in sync with runtime/runtime2.go:_defer.
  7806  func deferstruct() *types.Type {
  7807  	if deferType != nil {
  7808  		return deferType
  7809  	}
  7810  
  7811  	makefield := func(name string, t *types.Type) *types.Field {
  7812  		sym := (*types.Pkg)(nil).Lookup(name)
  7813  		return types.NewField(src.NoXPos, sym, t)
  7814  	}
  7815  
  7816  	fields := []*types.Field{
  7817  		makefield("heap", types.Types[types.TBOOL]),
  7818  		makefield("rangefunc", types.Types[types.TBOOL]),
  7819  		makefield("sp", types.Types[types.TUINTPTR]),
  7820  		makefield("pc", types.Types[types.TUINTPTR]),
  7821  		// Note: the types here don't really matter. Defer structures
  7822  		// are always scanned explicitly during stack copying and GC,
  7823  		// so we make them uintptr type even though they are real pointers.
  7824  		makefield("fn", types.Types[types.TUINTPTR]),
  7825  		makefield("link", types.Types[types.TUINTPTR]),
  7826  		makefield("head", types.Types[types.TUINTPTR]),
  7827  	}
  7828  	if name := fields[deferStructFnField].Sym.Name; name != "fn" {
  7829  		base.Fatalf("deferStructFnField is %q, not fn", name)
  7830  	}
  7831  
  7832  	n := ir.NewDeclNameAt(src.NoXPos, ir.OTYPE, ir.Pkgs.Runtime.Lookup("_defer"))
  7833  	typ := types.NewNamed(n)
  7834  	n.SetType(typ)
  7835  	n.SetTypecheck(1)
  7836  
  7837  	// build struct holding the above fields
  7838  	typ.SetUnderlying(types.NewStruct(fields))
  7839  	types.CalcStructSize(typ)
  7840  
  7841  	deferType = typ
  7842  	return typ
  7843  }
  7844  
  7845  // SpillSlotAddr uses LocalSlot information to initialize an obj.Addr
  7846  // The resulting addr is used in a non-standard context -- in the prologue
  7847  // of a function, before the frame has been constructed, so the standard
  7848  // addressing for the parameters will be wrong.
  7849  func SpillSlotAddr(spill ssa.Spill, baseReg int16, extraOffset int64) obj.Addr {
  7850  	return obj.Addr{
  7851  		Name:   obj.NAME_NONE,
  7852  		Type:   obj.TYPE_MEM,
  7853  		Reg:    baseReg,
  7854  		Offset: spill.Offset + extraOffset,
  7855  	}
  7856  }
  7857  
  7858  var BoundsCheckFunc [ssa.BoundsKindCount]*obj.LSym
  7859