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  	"fmt"
    11  	"go/constant"
    12  	"html"
    13  	"internal/buildcfg"
    14  	"os"
    15  	"path/filepath"
    16  	"slices"
    17  	"strings"
    18  
    19  	"cmd/compile/internal/abi"
    20  	"cmd/compile/internal/base"
    21  	"cmd/compile/internal/ir"
    22  	"cmd/compile/internal/liveness"
    23  	"cmd/compile/internal/objw"
    24  	"cmd/compile/internal/reflectdata"
    25  	"cmd/compile/internal/rttype"
    26  	"cmd/compile/internal/ssa"
    27  	"cmd/compile/internal/staticdata"
    28  	"cmd/compile/internal/typecheck"
    29  	"cmd/compile/internal/types"
    30  	"cmd/internal/obj"
    31  	"cmd/internal/objabi"
    32  	"cmd/internal/src"
    33  	"cmd/internal/sys"
    34  
    35  	rtabi "internal/abi"
    36  )
    37  
    38  var ssaConfig *ssa.Config
    39  var ssaCaches []ssa.Cache
    40  
    41  var ssaDump string     // early copy of $GOSSAFUNC; the func name to dump output for
    42  var ssaDir string      // optional destination for ssa dump file
    43  var ssaDumpStdout bool // whether to dump to stdout
    44  var ssaDumpCFG string  // generate CFGs for these phases
    45  const ssaDumpFile = "ssa.html"
    46  
    47  // ssaDumpInlined holds all inlined functions when ssaDump contains a function name.
    48  var ssaDumpInlined []*ir.Func
    49  
    50  func DumpInline(fn *ir.Func) {
    51  	if ssaDump != "" && ssaDump == ir.FuncName(fn) {
    52  		ssaDumpInlined = append(ssaDumpInlined, fn)
    53  	}
    54  }
    55  
    56  func InitEnv() {
    57  	ssaDump = os.Getenv("GOSSAFUNC")
    58  	ssaDir = os.Getenv("GOSSADIR")
    59  	if ssaDump != "" {
    60  		if strings.HasSuffix(ssaDump, "+") {
    61  			ssaDump = ssaDump[:len(ssaDump)-1]
    62  			ssaDumpStdout = true
    63  		}
    64  		spl := strings.Split(ssaDump, ":")
    65  		if len(spl) > 1 {
    66  			ssaDump = spl[0]
    67  			ssaDumpCFG = spl[1]
    68  		}
    69  	}
    70  }
    71  
    72  func InitConfig() {
    73  	types_ := ssa.NewTypes()
    74  
    75  	if Arch.SoftFloat {
    76  		softfloatInit()
    77  	}
    78  
    79  	// Generate a few pointer types that are uncommon in the frontend but common in the backend.
    80  	// Caching is disabled in the backend, so generating these here avoids allocations.
    81  	_ = types.NewPtr(types.Types[types.TINTER])                             // *interface{}
    82  	_ = types.NewPtr(types.NewPtr(types.Types[types.TSTRING]))              // **string
    83  	_ = types.NewPtr(types.NewSlice(types.Types[types.TINTER]))             // *[]interface{}
    84  	_ = types.NewPtr(types.NewPtr(types.ByteType))                          // **byte
    85  	_ = types.NewPtr(types.NewSlice(types.ByteType))                        // *[]byte
    86  	_ = types.NewPtr(types.NewSlice(types.Types[types.TSTRING]))            // *[]string
    87  	_ = types.NewPtr(types.NewPtr(types.NewPtr(types.Types[types.TUINT8]))) // ***uint8
    88  	_ = types.NewPtr(types.Types[types.TINT16])                             // *int16
    89  	_ = types.NewPtr(types.Types[types.TINT64])                             // *int64
    90  	_ = types.NewPtr(types.ErrorType)                                       // *error
    91  	if buildcfg.Experiment.SwissMap {
    92  		_ = types.NewPtr(reflectdata.SwissMapType()) // *internal/runtime/maps.Map
    93  	} else {
    94  		_ = types.NewPtr(reflectdata.OldMapType()) // *runtime.hmap
    95  	}
    96  	_ = types.NewPtr(deferstruct()) // *runtime._defer
    97  	types.NewPtrCacheEnabled = false
    98  	ssaConfig = ssa.NewConfig(base.Ctxt.Arch.Name, *types_, base.Ctxt, base.Flag.N == 0, Arch.SoftFloat)
    99  	ssaConfig.Race = base.Flag.Race
   100  	ssaCaches = make([]ssa.Cache, base.Flag.LowerC)
   101  
   102  	// Set up some runtime functions we'll need to call.
   103  	ir.Syms.AssertE2I = typecheck.LookupRuntimeFunc("assertE2I")
   104  	ir.Syms.AssertE2I2 = typecheck.LookupRuntimeFunc("assertE2I2")
   105  	ir.Syms.CgoCheckMemmove = typecheck.LookupRuntimeFunc("cgoCheckMemmove")
   106  	ir.Syms.CgoCheckPtrWrite = typecheck.LookupRuntimeFunc("cgoCheckPtrWrite")
   107  	ir.Syms.CheckPtrAlignment = typecheck.LookupRuntimeFunc("checkptrAlignment")
   108  	ir.Syms.Deferproc = typecheck.LookupRuntimeFunc("deferproc")
   109  	ir.Syms.Deferprocat = typecheck.LookupRuntimeFunc("deferprocat")
   110  	ir.Syms.DeferprocStack = typecheck.LookupRuntimeFunc("deferprocStack")
   111  	ir.Syms.Deferreturn = typecheck.LookupRuntimeFunc("deferreturn")
   112  	ir.Syms.Duffcopy = typecheck.LookupRuntimeFunc("duffcopy")
   113  	ir.Syms.Duffzero = typecheck.LookupRuntimeFunc("duffzero")
   114  	ir.Syms.GCWriteBarrier[0] = typecheck.LookupRuntimeFunc("gcWriteBarrier1")
   115  	ir.Syms.GCWriteBarrier[1] = typecheck.LookupRuntimeFunc("gcWriteBarrier2")
   116  	ir.Syms.GCWriteBarrier[2] = typecheck.LookupRuntimeFunc("gcWriteBarrier3")
   117  	ir.Syms.GCWriteBarrier[3] = typecheck.LookupRuntimeFunc("gcWriteBarrier4")
   118  	ir.Syms.GCWriteBarrier[4] = typecheck.LookupRuntimeFunc("gcWriteBarrier5")
   119  	ir.Syms.GCWriteBarrier[5] = typecheck.LookupRuntimeFunc("gcWriteBarrier6")
   120  	ir.Syms.GCWriteBarrier[6] = typecheck.LookupRuntimeFunc("gcWriteBarrier7")
   121  	ir.Syms.GCWriteBarrier[7] = typecheck.LookupRuntimeFunc("gcWriteBarrier8")
   122  	ir.Syms.Goschedguarded = typecheck.LookupRuntimeFunc("goschedguarded")
   123  	ir.Syms.Growslice = typecheck.LookupRuntimeFunc("growslice")
   124  	ir.Syms.InterfaceSwitch = typecheck.LookupRuntimeFunc("interfaceSwitch")
   125  	ir.Syms.Memmove = typecheck.LookupRuntimeFunc("memmove")
   126  	ir.Syms.Msanread = typecheck.LookupRuntimeFunc("msanread")
   127  	ir.Syms.Msanwrite = typecheck.LookupRuntimeFunc("msanwrite")
   128  	ir.Syms.Msanmove = typecheck.LookupRuntimeFunc("msanmove")
   129  	ir.Syms.Asanread = typecheck.LookupRuntimeFunc("asanread")
   130  	ir.Syms.Asanwrite = typecheck.LookupRuntimeFunc("asanwrite")
   131  	ir.Syms.Newobject = typecheck.LookupRuntimeFunc("newobject")
   132  	ir.Syms.Newproc = typecheck.LookupRuntimeFunc("newproc")
   133  	ir.Syms.Panicdivide = typecheck.LookupRuntimeFunc("panicdivide")
   134  	ir.Syms.PanicdottypeE = typecheck.LookupRuntimeFunc("panicdottypeE")
   135  	ir.Syms.PanicdottypeI = typecheck.LookupRuntimeFunc("panicdottypeI")
   136  	ir.Syms.Panicnildottype = typecheck.LookupRuntimeFunc("panicnildottype")
   137  	ir.Syms.Panicoverflow = typecheck.LookupRuntimeFunc("panicoverflow")
   138  	ir.Syms.Panicshift = typecheck.LookupRuntimeFunc("panicshift")
   139  	ir.Syms.Racefuncenter = typecheck.LookupRuntimeFunc("racefuncenter")
   140  	ir.Syms.Racefuncexit = typecheck.LookupRuntimeFunc("racefuncexit")
   141  	ir.Syms.Raceread = typecheck.LookupRuntimeFunc("raceread")
   142  	ir.Syms.Racereadrange = typecheck.LookupRuntimeFunc("racereadrange")
   143  	ir.Syms.Racewrite = typecheck.LookupRuntimeFunc("racewrite")
   144  	ir.Syms.Racewriterange = typecheck.LookupRuntimeFunc("racewriterange")
   145  	ir.Syms.TypeAssert = typecheck.LookupRuntimeFunc("typeAssert")
   146  	ir.Syms.WBZero = typecheck.LookupRuntimeFunc("wbZero")
   147  	ir.Syms.WBMove = typecheck.LookupRuntimeFunc("wbMove")
   148  	ir.Syms.X86HasPOPCNT = typecheck.LookupRuntimeVar("x86HasPOPCNT")         // bool
   149  	ir.Syms.X86HasSSE41 = typecheck.LookupRuntimeVar("x86HasSSE41")           // bool
   150  	ir.Syms.X86HasFMA = typecheck.LookupRuntimeVar("x86HasFMA")               // bool
   151  	ir.Syms.ARMHasVFPv4 = typecheck.LookupRuntimeVar("armHasVFPv4")           // bool
   152  	ir.Syms.ARM64HasATOMICS = typecheck.LookupRuntimeVar("arm64HasATOMICS")   // bool
   153  	ir.Syms.Loong64HasLAM_BH = typecheck.LookupRuntimeVar("loong64HasLAM_BH") // bool
   154  	ir.Syms.Loong64HasLSX = typecheck.LookupRuntimeVar("loong64HasLSX")       // bool
   155  	ir.Syms.Staticuint64s = typecheck.LookupRuntimeVar("staticuint64s")
   156  	ir.Syms.Typedmemmove = typecheck.LookupRuntimeFunc("typedmemmove")
   157  	ir.Syms.Udiv = typecheck.LookupRuntimeVar("udiv")                 // asm func with special ABI
   158  	ir.Syms.WriteBarrier = typecheck.LookupRuntimeVar("writeBarrier") // struct { bool; ... }
   159  	ir.Syms.Zerobase = typecheck.LookupRuntimeVar("zerobase")
   160  
   161  	if Arch.LinkArch.Family == sys.Wasm {
   162  		BoundsCheckFunc[ssa.BoundsIndex] = typecheck.LookupRuntimeFunc("goPanicIndex")
   163  		BoundsCheckFunc[ssa.BoundsIndexU] = typecheck.LookupRuntimeFunc("goPanicIndexU")
   164  		BoundsCheckFunc[ssa.BoundsSliceAlen] = typecheck.LookupRuntimeFunc("goPanicSliceAlen")
   165  		BoundsCheckFunc[ssa.BoundsSliceAlenU] = typecheck.LookupRuntimeFunc("goPanicSliceAlenU")
   166  		BoundsCheckFunc[ssa.BoundsSliceAcap] = typecheck.LookupRuntimeFunc("goPanicSliceAcap")
   167  		BoundsCheckFunc[ssa.BoundsSliceAcapU] = typecheck.LookupRuntimeFunc("goPanicSliceAcapU")
   168  		BoundsCheckFunc[ssa.BoundsSliceB] = typecheck.LookupRuntimeFunc("goPanicSliceB")
   169  		BoundsCheckFunc[ssa.BoundsSliceBU] = typecheck.LookupRuntimeFunc("goPanicSliceBU")
   170  		BoundsCheckFunc[ssa.BoundsSlice3Alen] = typecheck.LookupRuntimeFunc("goPanicSlice3Alen")
   171  		BoundsCheckFunc[ssa.BoundsSlice3AlenU] = typecheck.LookupRuntimeFunc("goPanicSlice3AlenU")
   172  		BoundsCheckFunc[ssa.BoundsSlice3Acap] = typecheck.LookupRuntimeFunc("goPanicSlice3Acap")
   173  		BoundsCheckFunc[ssa.BoundsSlice3AcapU] = typecheck.LookupRuntimeFunc("goPanicSlice3AcapU")
   174  		BoundsCheckFunc[ssa.BoundsSlice3B] = typecheck.LookupRuntimeFunc("goPanicSlice3B")
   175  		BoundsCheckFunc[ssa.BoundsSlice3BU] = typecheck.LookupRuntimeFunc("goPanicSlice3BU")
   176  		BoundsCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeFunc("goPanicSlice3C")
   177  		BoundsCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeFunc("goPanicSlice3CU")
   178  		BoundsCheckFunc[ssa.BoundsConvert] = typecheck.LookupRuntimeFunc("goPanicSliceConvert")
   179  	} else {
   180  		BoundsCheckFunc[ssa.BoundsIndex] = typecheck.LookupRuntimeFunc("panicIndex")
   181  		BoundsCheckFunc[ssa.BoundsIndexU] = typecheck.LookupRuntimeFunc("panicIndexU")
   182  		BoundsCheckFunc[ssa.BoundsSliceAlen] = typecheck.LookupRuntimeFunc("panicSliceAlen")
   183  		BoundsCheckFunc[ssa.BoundsSliceAlenU] = typecheck.LookupRuntimeFunc("panicSliceAlenU")
   184  		BoundsCheckFunc[ssa.BoundsSliceAcap] = typecheck.LookupRuntimeFunc("panicSliceAcap")
   185  		BoundsCheckFunc[ssa.BoundsSliceAcapU] = typecheck.LookupRuntimeFunc("panicSliceAcapU")
   186  		BoundsCheckFunc[ssa.BoundsSliceB] = typecheck.LookupRuntimeFunc("panicSliceB")
   187  		BoundsCheckFunc[ssa.BoundsSliceBU] = typecheck.LookupRuntimeFunc("panicSliceBU")
   188  		BoundsCheckFunc[ssa.BoundsSlice3Alen] = typecheck.LookupRuntimeFunc("panicSlice3Alen")
   189  		BoundsCheckFunc[ssa.BoundsSlice3AlenU] = typecheck.LookupRuntimeFunc("panicSlice3AlenU")
   190  		BoundsCheckFunc[ssa.BoundsSlice3Acap] = typecheck.LookupRuntimeFunc("panicSlice3Acap")
   191  		BoundsCheckFunc[ssa.BoundsSlice3AcapU] = typecheck.LookupRuntimeFunc("panicSlice3AcapU")
   192  		BoundsCheckFunc[ssa.BoundsSlice3B] = typecheck.LookupRuntimeFunc("panicSlice3B")
   193  		BoundsCheckFunc[ssa.BoundsSlice3BU] = typecheck.LookupRuntimeFunc("panicSlice3BU")
   194  		BoundsCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeFunc("panicSlice3C")
   195  		BoundsCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeFunc("panicSlice3CU")
   196  		BoundsCheckFunc[ssa.BoundsConvert] = typecheck.LookupRuntimeFunc("panicSliceConvert")
   197  	}
   198  	if Arch.LinkArch.PtrSize == 4 {
   199  		ExtendCheckFunc[ssa.BoundsIndex] = typecheck.LookupRuntimeVar("panicExtendIndex")
   200  		ExtendCheckFunc[ssa.BoundsIndexU] = typecheck.LookupRuntimeVar("panicExtendIndexU")
   201  		ExtendCheckFunc[ssa.BoundsSliceAlen] = typecheck.LookupRuntimeVar("panicExtendSliceAlen")
   202  		ExtendCheckFunc[ssa.BoundsSliceAlenU] = typecheck.LookupRuntimeVar("panicExtendSliceAlenU")
   203  		ExtendCheckFunc[ssa.BoundsSliceAcap] = typecheck.LookupRuntimeVar("panicExtendSliceAcap")
   204  		ExtendCheckFunc[ssa.BoundsSliceAcapU] = typecheck.LookupRuntimeVar("panicExtendSliceAcapU")
   205  		ExtendCheckFunc[ssa.BoundsSliceB] = typecheck.LookupRuntimeVar("panicExtendSliceB")
   206  		ExtendCheckFunc[ssa.BoundsSliceBU] = typecheck.LookupRuntimeVar("panicExtendSliceBU")
   207  		ExtendCheckFunc[ssa.BoundsSlice3Alen] = typecheck.LookupRuntimeVar("panicExtendSlice3Alen")
   208  		ExtendCheckFunc[ssa.BoundsSlice3AlenU] = typecheck.LookupRuntimeVar("panicExtendSlice3AlenU")
   209  		ExtendCheckFunc[ssa.BoundsSlice3Acap] = typecheck.LookupRuntimeVar("panicExtendSlice3Acap")
   210  		ExtendCheckFunc[ssa.BoundsSlice3AcapU] = typecheck.LookupRuntimeVar("panicExtendSlice3AcapU")
   211  		ExtendCheckFunc[ssa.BoundsSlice3B] = typecheck.LookupRuntimeVar("panicExtendSlice3B")
   212  		ExtendCheckFunc[ssa.BoundsSlice3BU] = typecheck.LookupRuntimeVar("panicExtendSlice3BU")
   213  		ExtendCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeVar("panicExtendSlice3C")
   214  		ExtendCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeVar("panicExtendSlice3CU")
   215  	}
   216  
   217  	// Wasm (all asm funcs with special ABIs)
   218  	ir.Syms.WasmDiv = typecheck.LookupRuntimeVar("wasmDiv")
   219  	ir.Syms.WasmTruncS = typecheck.LookupRuntimeVar("wasmTruncS")
   220  	ir.Syms.WasmTruncU = typecheck.LookupRuntimeVar("wasmTruncU")
   221  	ir.Syms.SigPanic = typecheck.LookupRuntimeFunc("sigpanic")
   222  }
   223  
   224  func InitTables() {
   225  	initIntrinsics(nil)
   226  }
   227  
   228  // AbiForBodylessFuncStackMap returns the ABI for a bodyless function's stack map.
   229  // This is not necessarily the ABI used to call it.
   230  // Currently (1.17 dev) such a stack map is always ABI0;
   231  // any ABI wrapper that is present is nosplit, hence a precise
   232  // stack map is not needed there (the parameters survive only long
   233  // enough to call the wrapped assembly function).
   234  // This always returns a freshly copied ABI.
   235  func AbiForBodylessFuncStackMap(fn *ir.Func) *abi.ABIConfig {
   236  	return ssaConfig.ABI0.Copy() // No idea what races will result, be safe
   237  }
   238  
   239  // abiForFunc implements ABI policy for a function, but does not return a copy of the ABI.
   240  // Passing a nil function returns the default ABI based on experiment configuration.
   241  func abiForFunc(fn *ir.Func, abi0, abi1 *abi.ABIConfig) *abi.ABIConfig {
   242  	if buildcfg.Experiment.RegabiArgs {
   243  		// Select the ABI based on the function's defining ABI.
   244  		if fn == nil {
   245  			return abi1
   246  		}
   247  		switch fn.ABI {
   248  		case obj.ABI0:
   249  			return abi0
   250  		case obj.ABIInternal:
   251  			// TODO(austin): Clean up the nomenclature here.
   252  			// It's not clear that "abi1" is ABIInternal.
   253  			return abi1
   254  		}
   255  		base.Fatalf("function %v has unknown ABI %v", fn, fn.ABI)
   256  		panic("not reachable")
   257  	}
   258  
   259  	a := abi0
   260  	if fn != nil {
   261  		if fn.Pragma&ir.RegisterParams != 0 { // TODO(register args) remove after register abi is working
   262  			a = abi1
   263  		}
   264  	}
   265  	return a
   266  }
   267  
   268  // emitOpenDeferInfo emits FUNCDATA information about the defers in a function
   269  // that is using open-coded defers.  This funcdata is used to determine the active
   270  // defers in a function and execute those defers during panic processing.
   271  //
   272  // The funcdata is all encoded in varints (since values will almost always be less than
   273  // 128, but stack offsets could potentially be up to 2Gbyte). All "locations" (offsets)
   274  // for stack variables are specified as the number of bytes below varp (pointer to the
   275  // top of the local variables) for their starting address. The format is:
   276  //
   277  //   - Offset of the deferBits variable
   278  //   - Offset of the first closure slot (the rest are laid out consecutively).
   279  func (s *state) emitOpenDeferInfo() {
   280  	firstOffset := s.openDefers[0].closureNode.FrameOffset()
   281  
   282  	// Verify that cmpstackvarlt laid out the slots in order.
   283  	for i, r := range s.openDefers {
   284  		have := r.closureNode.FrameOffset()
   285  		want := firstOffset + int64(i)*int64(types.PtrSize)
   286  		if have != want {
   287  			base.FatalfAt(s.curfn.Pos(), "unexpected frame offset for open-coded defer slot #%v: have %v, want %v", i, have, want)
   288  		}
   289  	}
   290  
   291  	x := base.Ctxt.Lookup(s.curfn.LSym.Name + ".opendefer")
   292  	x.Set(obj.AttrContentAddressable, true)
   293  	s.curfn.LSym.Func().OpenCodedDeferInfo = x
   294  
   295  	off := 0
   296  	off = objw.Uvarint(x, off, uint64(-s.deferBitsTemp.FrameOffset()))
   297  	off = objw.Uvarint(x, off, uint64(-firstOffset))
   298  }
   299  
   300  // buildssa builds an SSA function for fn.
   301  // worker indicates which of the backend workers is doing the processing.
   302  func buildssa(fn *ir.Func, worker int, isPgoHot bool) *ssa.Func {
   303  	name := ir.FuncName(fn)
   304  
   305  	abiSelf := abiForFunc(fn, ssaConfig.ABI0, ssaConfig.ABI1)
   306  
   307  	printssa := false
   308  	// match either a simple name e.g. "(*Reader).Reset", package.name e.g. "compress/gzip.(*Reader).Reset", or subpackage name "gzip.(*Reader).Reset"
   309  	// optionally allows an ABI suffix specification in the GOSSAHASH, e.g. "(*Reader).Reset<0>" etc
   310  	if strings.Contains(ssaDump, name) { // in all the cases the function name is entirely contained within the GOSSAFUNC string.
   311  		nameOptABI := name
   312  		if strings.Contains(ssaDump, ",") { // ABI specification
   313  			nameOptABI = ssa.FuncNameABI(name, abiSelf.Which())
   314  		} else if strings.HasSuffix(ssaDump, ">") { // if they use the linker syntax instead....
   315  			l := len(ssaDump)
   316  			if l >= 3 && ssaDump[l-3] == '<' {
   317  				nameOptABI = ssa.FuncNameABI(name, abiSelf.Which())
   318  				ssaDump = ssaDump[:l-3] + "," + ssaDump[l-2:l-1]
   319  			}
   320  		}
   321  		pkgDotName := base.Ctxt.Pkgpath + "." + nameOptABI
   322  		printssa = nameOptABI == ssaDump || // "(*Reader).Reset"
   323  			pkgDotName == ssaDump || // "compress/gzip.(*Reader).Reset"
   324  			strings.HasSuffix(pkgDotName, ssaDump) && strings.HasSuffix(pkgDotName, "/"+ssaDump) // "gzip.(*Reader).Reset"
   325  	}
   326  
   327  	var astBuf *bytes.Buffer
   328  	if printssa {
   329  		astBuf = &bytes.Buffer{}
   330  		ir.FDumpList(astBuf, "buildssa-body", fn.Body)
   331  		if ssaDumpStdout {
   332  			fmt.Println("generating SSA for", name)
   333  			fmt.Print(astBuf.String())
   334  		}
   335  	}
   336  
   337  	var s state
   338  	s.pushLine(fn.Pos())
   339  	defer s.popLine()
   340  
   341  	s.hasdefer = fn.HasDefer()
   342  	if fn.Pragma&ir.CgoUnsafeArgs != 0 {
   343  		s.cgoUnsafeArgs = true
   344  	}
   345  	s.checkPtrEnabled = ir.ShouldCheckPtr(fn, 1)
   346  
   347  	if base.Flag.Cfg.Instrumenting && fn.Pragma&ir.Norace == 0 && !fn.Linksym().ABIWrapper() {
   348  		if !base.Flag.Race || !objabi.LookupPkgSpecial(fn.Sym().Pkg.Path).NoRaceFunc {
   349  			s.instrumentMemory = true
   350  		}
   351  		if base.Flag.Race {
   352  			s.instrumentEnterExit = true
   353  		}
   354  	}
   355  
   356  	fe := ssafn{
   357  		curfn: fn,
   358  		log:   printssa && ssaDumpStdout,
   359  	}
   360  	s.curfn = fn
   361  
   362  	cache := &ssaCaches[worker]
   363  	cache.Reset()
   364  
   365  	s.f = ssaConfig.NewFunc(&fe, cache)
   366  	s.config = ssaConfig
   367  	s.f.Type = fn.Type()
   368  	s.f.Name = name
   369  	s.f.PrintOrHtmlSSA = printssa
   370  	if fn.Pragma&ir.Nosplit != 0 {
   371  		s.f.NoSplit = true
   372  	}
   373  	s.f.ABI0 = ssaConfig.ABI0
   374  	s.f.ABI1 = ssaConfig.ABI1
   375  	s.f.ABIDefault = abiForFunc(nil, ssaConfig.ABI0, ssaConfig.ABI1)
   376  	s.f.ABISelf = abiSelf
   377  
   378  	s.panics = map[funcLine]*ssa.Block{}
   379  	s.softFloat = s.config.SoftFloat
   380  
   381  	// Allocate starting block
   382  	s.f.Entry = s.f.NewBlock(ssa.BlockPlain)
   383  	s.f.Entry.Pos = fn.Pos()
   384  	s.f.IsPgoHot = isPgoHot
   385  
   386  	if printssa {
   387  		ssaDF := ssaDumpFile
   388  		if ssaDir != "" {
   389  			ssaDF = filepath.Join(ssaDir, base.Ctxt.Pkgpath+"."+s.f.NameABI()+".html")
   390  			ssaD := filepath.Dir(ssaDF)
   391  			os.MkdirAll(ssaD, 0755)
   392  		}
   393  		s.f.HTMLWriter = ssa.NewHTMLWriter(ssaDF, s.f, ssaDumpCFG)
   394  		// TODO: generate and print a mapping from nodes to values and blocks
   395  		dumpSourcesColumn(s.f.HTMLWriter, fn)
   396  		s.f.HTMLWriter.WriteAST("AST", astBuf)
   397  	}
   398  
   399  	// Allocate starting values
   400  	s.labels = map[string]*ssaLabel{}
   401  	s.fwdVars = map[ir.Node]*ssa.Value{}
   402  	s.startmem = s.entryNewValue0(ssa.OpInitMem, types.TypeMem)
   403  
   404  	s.hasOpenDefers = base.Flag.N == 0 && s.hasdefer && !s.curfn.OpenCodedDeferDisallowed()
   405  	switch {
   406  	case base.Debug.NoOpenDefer != 0:
   407  		s.hasOpenDefers = false
   408  	case s.hasOpenDefers && (base.Ctxt.Flag_shared || base.Ctxt.Flag_dynlink) && base.Ctxt.Arch.Name == "386":
   409  		// Don't support open-coded defers for 386 ONLY when using shared
   410  		// libraries, because there is extra code (added by rewriteToUseGot())
   411  		// preceding the deferreturn/ret code that we don't track correctly.
   412  		s.hasOpenDefers = false
   413  	}
   414  	if s.hasOpenDefers && s.instrumentEnterExit {
   415  		// Skip doing open defers if we need to instrument function
   416  		// returns for the race detector, since we will not generate that
   417  		// code in the case of the extra deferreturn/ret segment.
   418  		s.hasOpenDefers = false
   419  	}
   420  	if s.hasOpenDefers {
   421  		// Similarly, skip if there are any heap-allocated result
   422  		// parameters that need to be copied back to their stack slots.
   423  		for _, f := range s.curfn.Type().Results() {
   424  			if !f.Nname.(*ir.Name).OnStack() {
   425  				s.hasOpenDefers = false
   426  				break
   427  			}
   428  		}
   429  	}
   430  	if s.hasOpenDefers &&
   431  		s.curfn.NumReturns*s.curfn.NumDefers > 15 {
   432  		// Since we are generating defer calls at every exit for
   433  		// open-coded defers, skip doing open-coded defers if there are
   434  		// too many returns (especially if there are multiple defers).
   435  		// Open-coded defers are most important for improving performance
   436  		// for smaller functions (which don't have many returns).
   437  		s.hasOpenDefers = false
   438  	}
   439  
   440  	s.sp = s.entryNewValue0(ssa.OpSP, types.Types[types.TUINTPTR]) // TODO: use generic pointer type (unsafe.Pointer?) instead
   441  	s.sb = s.entryNewValue0(ssa.OpSB, types.Types[types.TUINTPTR])
   442  
   443  	s.startBlock(s.f.Entry)
   444  	s.vars[memVar] = s.startmem
   445  	if s.hasOpenDefers {
   446  		// Create the deferBits variable and stack slot.  deferBits is a
   447  		// bitmask showing which of the open-coded defers in this function
   448  		// have been activated.
   449  		deferBitsTemp := typecheck.TempAt(src.NoXPos, s.curfn, types.Types[types.TUINT8])
   450  		deferBitsTemp.SetAddrtaken(true)
   451  		s.deferBitsTemp = deferBitsTemp
   452  		// For this value, AuxInt is initialized to zero by default
   453  		startDeferBits := s.entryNewValue0(ssa.OpConst8, types.Types[types.TUINT8])
   454  		s.vars[deferBitsVar] = startDeferBits
   455  		s.deferBitsAddr = s.addr(deferBitsTemp)
   456  		s.store(types.Types[types.TUINT8], s.deferBitsAddr, startDeferBits)
   457  		// Make sure that the deferBits stack slot is kept alive (for use
   458  		// by panics) and stores to deferBits are not eliminated, even if
   459  		// all checking code on deferBits in the function exit can be
   460  		// eliminated, because the defer statements were all
   461  		// unconditional.
   462  		s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, deferBitsTemp, s.mem(), false)
   463  	}
   464  
   465  	var params *abi.ABIParamResultInfo
   466  	params = s.f.ABISelf.ABIAnalyze(fn.Type(), true)
   467  
   468  	// The backend's stackframe pass prunes away entries from the fn's
   469  	// Dcl list, including PARAMOUT nodes that correspond to output
   470  	// params passed in registers. Walk the Dcl list and capture these
   471  	// nodes to a side list, so that we'll have them available during
   472  	// DWARF-gen later on. See issue 48573 for more details.
   473  	var debugInfo ssa.FuncDebug
   474  	for _, n := range fn.Dcl {
   475  		if n.Class == ir.PPARAMOUT && n.IsOutputParamInRegisters() {
   476  			debugInfo.RegOutputParams = append(debugInfo.RegOutputParams, n)
   477  		}
   478  	}
   479  	fn.DebugInfo = &debugInfo
   480  
   481  	// Generate addresses of local declarations
   482  	s.decladdrs = map[*ir.Name]*ssa.Value{}
   483  	for _, n := range fn.Dcl {
   484  		switch n.Class {
   485  		case ir.PPARAM:
   486  			// Be aware that blank and unnamed input parameters will not appear here, but do appear in the type
   487  			s.decladdrs[n] = s.entryNewValue2A(ssa.OpLocalAddr, types.NewPtr(n.Type()), n, s.sp, s.startmem)
   488  		case ir.PPARAMOUT:
   489  			s.decladdrs[n] = s.entryNewValue2A(ssa.OpLocalAddr, types.NewPtr(n.Type()), n, s.sp, s.startmem)
   490  		case ir.PAUTO:
   491  			// processed at each use, to prevent Addr coming
   492  			// before the decl.
   493  		default:
   494  			s.Fatalf("local variable with class %v unimplemented", n.Class)
   495  		}
   496  	}
   497  
   498  	s.f.OwnAux = ssa.OwnAuxCall(fn.LSym, params)
   499  
   500  	// Populate SSAable arguments.
   501  	for _, n := range fn.Dcl {
   502  		if n.Class == ir.PPARAM {
   503  			if s.canSSA(n) {
   504  				v := s.newValue0A(ssa.OpArg, n.Type(), n)
   505  				s.vars[n] = v
   506  				s.addNamedValue(n, v) // This helps with debugging information, not needed for compilation itself.
   507  			} else { // address was taken AND/OR too large for SSA
   508  				paramAssignment := ssa.ParamAssignmentForArgName(s.f, n)
   509  				if len(paramAssignment.Registers) > 0 {
   510  					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.
   511  						v := s.newValue0A(ssa.OpArg, n.Type(), n)
   512  						s.store(n.Type(), s.decladdrs[n], v)
   513  					} else { // Too big for SSA.
   514  						// Brute force, and early, do a bunch of stores from registers
   515  						// Note that expand calls knows about this and doesn't trouble itself with larger-than-SSA-able Args in registers.
   516  						s.storeParameterRegsToStack(s.f.ABISelf, paramAssignment, n, s.decladdrs[n], false)
   517  					}
   518  				}
   519  			}
   520  		}
   521  	}
   522  
   523  	// Populate closure variables.
   524  	if fn.Needctxt() {
   525  		clo := s.entryNewValue0(ssa.OpGetClosurePtr, s.f.Config.Types.BytePtr)
   526  		if fn.RangeParent != nil && base.Flag.N != 0 {
   527  			// For a range body closure, keep its closure pointer live on the
   528  			// stack with a special name, so the debugger can look for it and
   529  			// find the parent frame.
   530  			sym := &types.Sym{Name: ".closureptr", Pkg: types.LocalPkg}
   531  			cloSlot := s.curfn.NewLocal(src.NoXPos, sym, s.f.Config.Types.BytePtr)
   532  			cloSlot.SetUsed(true)
   533  			cloSlot.SetEsc(ir.EscNever)
   534  			cloSlot.SetAddrtaken(true)
   535  			s.f.CloSlot = cloSlot
   536  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, cloSlot, s.mem(), false)
   537  			addr := s.addr(cloSlot)
   538  			s.store(s.f.Config.Types.BytePtr, addr, clo)
   539  			// Keep it from being dead-store eliminated.
   540  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, cloSlot, s.mem(), false)
   541  		}
   542  		csiter := typecheck.NewClosureStructIter(fn.ClosureVars)
   543  		for {
   544  			n, typ, offset := csiter.Next()
   545  			if n == nil {
   546  				break
   547  			}
   548  
   549  			ptr := s.newValue1I(ssa.OpOffPtr, types.NewPtr(typ), offset, clo)
   550  
   551  			// If n is a small variable captured by value, promote
   552  			// it to PAUTO so it can be converted to SSA.
   553  			//
   554  			// Note: While we never capture a variable by value if
   555  			// the user took its address, we may have generated
   556  			// runtime calls that did (#43701). Since we don't
   557  			// convert Addrtaken variables to SSA anyway, no point
   558  			// in promoting them either.
   559  			if n.Byval() && !n.Addrtaken() && ssa.CanSSA(n.Type()) {
   560  				n.Class = ir.PAUTO
   561  				fn.Dcl = append(fn.Dcl, n)
   562  				s.assign(n, s.load(n.Type(), ptr), false, 0)
   563  				continue
   564  			}
   565  
   566  			if !n.Byval() {
   567  				ptr = s.load(typ, ptr)
   568  			}
   569  			s.setHeapaddr(fn.Pos(), n, ptr)
   570  		}
   571  	}
   572  
   573  	// Convert the AST-based IR to the SSA-based IR
   574  	if s.instrumentEnterExit {
   575  		s.rtcall(ir.Syms.Racefuncenter, true, nil, s.newValue0(ssa.OpGetCallerPC, types.Types[types.TUINTPTR]))
   576  	}
   577  	s.zeroResults()
   578  	s.paramsToHeap()
   579  	s.stmtList(fn.Body)
   580  
   581  	// fallthrough to exit
   582  	if s.curBlock != nil {
   583  		s.pushLine(fn.Endlineno)
   584  		s.exit()
   585  		s.popLine()
   586  	}
   587  
   588  	for _, b := range s.f.Blocks {
   589  		if b.Pos != src.NoXPos {
   590  			s.updateUnsetPredPos(b)
   591  		}
   592  	}
   593  
   594  	s.f.HTMLWriter.WritePhase("before insert phis", "before insert phis")
   595  
   596  	s.insertPhis()
   597  
   598  	// Main call to ssa package to compile function
   599  	ssa.Compile(s.f)
   600  
   601  	fe.AllocFrame(s.f)
   602  
   603  	if len(s.openDefers) != 0 {
   604  		s.emitOpenDeferInfo()
   605  	}
   606  
   607  	// Record incoming parameter spill information for morestack calls emitted in the assembler.
   608  	// This is done here, using all the parameters (used, partially used, and unused) because
   609  	// it mimics the behavior of the former ABI (everything stored) and because it's not 100%
   610  	// clear if naming conventions are respected in autogenerated code.
   611  	// TODO figure out exactly what's unused, don't spill it. Make liveness fine-grained, also.
   612  	for _, p := range params.InParams() {
   613  		typs, offs := p.RegisterTypesAndOffsets()
   614  		for i, t := range typs {
   615  			o := offs[i]                // offset within parameter
   616  			fo := p.FrameOffset(params) // offset of parameter in frame
   617  			reg := ssa.ObjRegForAbiReg(p.Registers[i], s.f.Config)
   618  			s.f.RegArgs = append(s.f.RegArgs, ssa.Spill{Reg: reg, Offset: fo + o, Type: t})
   619  		}
   620  	}
   621  
   622  	return s.f
   623  }
   624  
   625  func (s *state) storeParameterRegsToStack(abi *abi.ABIConfig, paramAssignment *abi.ABIParamAssignment, n *ir.Name, addr *ssa.Value, pointersOnly bool) {
   626  	typs, offs := paramAssignment.RegisterTypesAndOffsets()
   627  	for i, t := range typs {
   628  		if pointersOnly && !t.IsPtrShaped() {
   629  			continue
   630  		}
   631  		r := paramAssignment.Registers[i]
   632  		o := offs[i]
   633  		op, reg := ssa.ArgOpAndRegisterFor(r, abi)
   634  		aux := &ssa.AuxNameOffset{Name: n, Offset: o}
   635  		v := s.newValue0I(op, t, reg)
   636  		v.Aux = aux
   637  		p := s.newValue1I(ssa.OpOffPtr, types.NewPtr(t), o, addr)
   638  		s.store(t, p, v)
   639  	}
   640  }
   641  
   642  // zeroResults zeros the return values at the start of the function.
   643  // We need to do this very early in the function.  Defer might stop a
   644  // panic and show the return values as they exist at the time of
   645  // panic.  For precise stacks, the garbage collector assumes results
   646  // are always live, so we need to zero them before any allocations,
   647  // even allocations to move params/results to the heap.
   648  func (s *state) zeroResults() {
   649  	for _, f := range s.curfn.Type().Results() {
   650  		n := f.Nname.(*ir.Name)
   651  		if !n.OnStack() {
   652  			// The local which points to the return value is the
   653  			// thing that needs zeroing. This is already handled
   654  			// by a Needzero annotation in plive.go:(*liveness).epilogue.
   655  			continue
   656  		}
   657  		// Zero the stack location containing f.
   658  		if typ := n.Type(); ssa.CanSSA(typ) {
   659  			s.assign(n, s.zeroVal(typ), false, 0)
   660  		} else {
   661  			if typ.HasPointers() || ssa.IsMergeCandidate(n) {
   662  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
   663  			}
   664  			s.zero(n.Type(), s.decladdrs[n])
   665  		}
   666  	}
   667  }
   668  
   669  // paramsToHeap produces code to allocate memory for heap-escaped parameters
   670  // and to copy non-result parameters' values from the stack.
   671  func (s *state) paramsToHeap() {
   672  	do := func(params []*types.Field) {
   673  		for _, f := range params {
   674  			if f.Nname == nil {
   675  				continue // anonymous or blank parameter
   676  			}
   677  			n := f.Nname.(*ir.Name)
   678  			if ir.IsBlank(n) || n.OnStack() {
   679  				continue
   680  			}
   681  			s.newHeapaddr(n)
   682  			if n.Class == ir.PPARAM {
   683  				s.move(n.Type(), s.expr(n.Heapaddr), s.decladdrs[n])
   684  			}
   685  		}
   686  	}
   687  
   688  	typ := s.curfn.Type()
   689  	do(typ.Recvs())
   690  	do(typ.Params())
   691  	do(typ.Results())
   692  }
   693  
   694  // newHeapaddr allocates heap memory for n and sets its heap address.
   695  func (s *state) newHeapaddr(n *ir.Name) {
   696  	s.setHeapaddr(n.Pos(), n, s.newObject(n.Type(), nil))
   697  }
   698  
   699  // setHeapaddr allocates a new PAUTO variable to store ptr (which must be non-nil)
   700  // and then sets it as n's heap address.
   701  func (s *state) setHeapaddr(pos src.XPos, n *ir.Name, ptr *ssa.Value) {
   702  	if !ptr.Type.IsPtr() || !types.Identical(n.Type(), ptr.Type.Elem()) {
   703  		base.FatalfAt(n.Pos(), "setHeapaddr %L with type %v", n, ptr.Type)
   704  	}
   705  
   706  	// Declare variable to hold address.
   707  	sym := &types.Sym{Name: "&" + n.Sym().Name, Pkg: types.LocalPkg}
   708  	addr := s.curfn.NewLocal(pos, sym, types.NewPtr(n.Type()))
   709  	addr.SetUsed(true)
   710  	types.CalcSize(addr.Type())
   711  
   712  	if n.Class == ir.PPARAMOUT {
   713  		addr.SetIsOutputParamHeapAddr(true)
   714  	}
   715  
   716  	n.Heapaddr = addr
   717  	s.assign(addr, ptr, false, 0)
   718  }
   719  
   720  // newObject returns an SSA value denoting new(typ).
   721  func (s *state) newObject(typ *types.Type, rtype *ssa.Value) *ssa.Value {
   722  	if typ.Size() == 0 {
   723  		return s.newValue1A(ssa.OpAddr, types.NewPtr(typ), ir.Syms.Zerobase, s.sb)
   724  	}
   725  	if rtype == nil {
   726  		rtype = s.reflectType(typ)
   727  	}
   728  	return s.rtcall(ir.Syms.Newobject, true, []*types.Type{types.NewPtr(typ)}, rtype)[0]
   729  }
   730  
   731  func (s *state) checkPtrAlignment(n *ir.ConvExpr, v *ssa.Value, count *ssa.Value) {
   732  	if !n.Type().IsPtr() {
   733  		s.Fatalf("expected pointer type: %v", n.Type())
   734  	}
   735  	elem, rtypeExpr := n.Type().Elem(), n.ElemRType
   736  	if count != nil {
   737  		if !elem.IsArray() {
   738  			s.Fatalf("expected array type: %v", elem)
   739  		}
   740  		elem, rtypeExpr = elem.Elem(), n.ElemElemRType
   741  	}
   742  	size := elem.Size()
   743  	// Casting from larger type to smaller one is ok, so for smallest type, do nothing.
   744  	if elem.Alignment() == 1 && (size == 0 || size == 1 || count == nil) {
   745  		return
   746  	}
   747  	if count == nil {
   748  		count = s.constInt(types.Types[types.TUINTPTR], 1)
   749  	}
   750  	if count.Type.Size() != s.config.PtrSize {
   751  		s.Fatalf("expected count fit to a uintptr size, have: %d, want: %d", count.Type.Size(), s.config.PtrSize)
   752  	}
   753  	var rtype *ssa.Value
   754  	if rtypeExpr != nil {
   755  		rtype = s.expr(rtypeExpr)
   756  	} else {
   757  		rtype = s.reflectType(elem)
   758  	}
   759  	s.rtcall(ir.Syms.CheckPtrAlignment, true, nil, v, rtype, count)
   760  }
   761  
   762  // reflectType returns an SSA value representing a pointer to typ's
   763  // reflection type descriptor.
   764  func (s *state) reflectType(typ *types.Type) *ssa.Value {
   765  	// TODO(mdempsky): Make this Fatalf under Unified IR; frontend needs
   766  	// to supply RType expressions.
   767  	lsym := reflectdata.TypeLinksym(typ)
   768  	return s.entryNewValue1A(ssa.OpAddr, types.NewPtr(types.Types[types.TUINT8]), lsym, s.sb)
   769  }
   770  
   771  func dumpSourcesColumn(writer *ssa.HTMLWriter, fn *ir.Func) {
   772  	// Read sources of target function fn.
   773  	fname := base.Ctxt.PosTable.Pos(fn.Pos()).Filename()
   774  	targetFn, err := readFuncLines(fname, fn.Pos().Line(), fn.Endlineno.Line())
   775  	if err != nil {
   776  		writer.Logf("cannot read sources for function %v: %v", fn, err)
   777  	}
   778  
   779  	// Read sources of inlined functions.
   780  	var inlFns []*ssa.FuncLines
   781  	for _, fi := range ssaDumpInlined {
   782  		elno := fi.Endlineno
   783  		fname := base.Ctxt.PosTable.Pos(fi.Pos()).Filename()
   784  		fnLines, err := readFuncLines(fname, fi.Pos().Line(), elno.Line())
   785  		if err != nil {
   786  			writer.Logf("cannot read sources for inlined function %v: %v", fi, err)
   787  			continue
   788  		}
   789  		inlFns = append(inlFns, fnLines)
   790  	}
   791  
   792  	slices.SortFunc(inlFns, ssa.ByTopoCmp)
   793  	if targetFn != nil {
   794  		inlFns = append([]*ssa.FuncLines{targetFn}, inlFns...)
   795  	}
   796  
   797  	writer.WriteSources("sources", inlFns)
   798  }
   799  
   800  func readFuncLines(file string, start, end uint) (*ssa.FuncLines, error) {
   801  	f, err := os.Open(os.ExpandEnv(file))
   802  	if err != nil {
   803  		return nil, err
   804  	}
   805  	defer f.Close()
   806  	var lines []string
   807  	ln := uint(1)
   808  	scanner := bufio.NewScanner(f)
   809  	for scanner.Scan() && ln <= end {
   810  		if ln >= start {
   811  			lines = append(lines, scanner.Text())
   812  		}
   813  		ln++
   814  	}
   815  	return &ssa.FuncLines{Filename: file, StartLineno: start, Lines: lines}, nil
   816  }
   817  
   818  // updateUnsetPredPos propagates the earliest-value position information for b
   819  // towards all of b's predecessors that need a position, and recurs on that
   820  // predecessor if its position is updated. B should have a non-empty position.
   821  func (s *state) updateUnsetPredPos(b *ssa.Block) {
   822  	if b.Pos == src.NoXPos {
   823  		s.Fatalf("Block %s should have a position", b)
   824  	}
   825  	bestPos := src.NoXPos
   826  	for _, e := range b.Preds {
   827  		p := e.Block()
   828  		if !p.LackingPos() {
   829  			continue
   830  		}
   831  		if bestPos == src.NoXPos {
   832  			bestPos = b.Pos
   833  			for _, v := range b.Values {
   834  				if v.LackingPos() {
   835  					continue
   836  				}
   837  				if v.Pos != src.NoXPos {
   838  					// Assume values are still in roughly textual order;
   839  					// TODO: could also seek minimum position?
   840  					bestPos = v.Pos
   841  					break
   842  				}
   843  			}
   844  		}
   845  		p.Pos = bestPos
   846  		s.updateUnsetPredPos(p) // We do not expect long chains of these, thus recursion is okay.
   847  	}
   848  }
   849  
   850  // Information about each open-coded defer.
   851  type openDeferInfo struct {
   852  	// The node representing the call of the defer
   853  	n *ir.CallExpr
   854  	// If defer call is closure call, the address of the argtmp where the
   855  	// closure is stored.
   856  	closure *ssa.Value
   857  	// The node representing the argtmp where the closure is stored - used for
   858  	// function, method, or interface call, to store a closure that panic
   859  	// processing can use for this defer.
   860  	closureNode *ir.Name
   861  }
   862  
   863  type state struct {
   864  	// configuration (arch) information
   865  	config *ssa.Config
   866  
   867  	// function we're building
   868  	f *ssa.Func
   869  
   870  	// Node for function
   871  	curfn *ir.Func
   872  
   873  	// labels in f
   874  	labels map[string]*ssaLabel
   875  
   876  	// unlabeled break and continue statement tracking
   877  	breakTo    *ssa.Block // current target for plain break statement
   878  	continueTo *ssa.Block // current target for plain continue statement
   879  
   880  	// current location where we're interpreting the AST
   881  	curBlock *ssa.Block
   882  
   883  	// variable assignments in the current block (map from variable symbol to ssa value)
   884  	// *Node is the unique identifier (an ONAME Node) for the variable.
   885  	// TODO: keep a single varnum map, then make all of these maps slices instead?
   886  	vars map[ir.Node]*ssa.Value
   887  
   888  	// fwdVars are variables that are used before they are defined in the current block.
   889  	// This map exists just to coalesce multiple references into a single FwdRef op.
   890  	// *Node is the unique identifier (an ONAME Node) for the variable.
   891  	fwdVars map[ir.Node]*ssa.Value
   892  
   893  	// all defined variables at the end of each block. Indexed by block ID.
   894  	defvars []map[ir.Node]*ssa.Value
   895  
   896  	// addresses of PPARAM and PPARAMOUT variables on the stack.
   897  	decladdrs map[*ir.Name]*ssa.Value
   898  
   899  	// starting values. Memory, stack pointer, and globals pointer
   900  	startmem *ssa.Value
   901  	sp       *ssa.Value
   902  	sb       *ssa.Value
   903  	// value representing address of where deferBits autotmp is stored
   904  	deferBitsAddr *ssa.Value
   905  	deferBitsTemp *ir.Name
   906  
   907  	// line number stack. The current line number is top of stack
   908  	line []src.XPos
   909  	// the last line number processed; it may have been popped
   910  	lastPos src.XPos
   911  
   912  	// list of panic calls by function name and line number.
   913  	// Used to deduplicate panic calls.
   914  	panics map[funcLine]*ssa.Block
   915  
   916  	cgoUnsafeArgs       bool
   917  	hasdefer            bool // whether the function contains a defer statement
   918  	softFloat           bool
   919  	hasOpenDefers       bool // whether we are doing open-coded defers
   920  	checkPtrEnabled     bool // whether to insert checkptr instrumentation
   921  	instrumentEnterExit bool // whether to instrument function enter/exit
   922  	instrumentMemory    bool // whether to instrument memory operations
   923  
   924  	// If doing open-coded defers, list of info about the defer calls in
   925  	// scanning order. Hence, at exit we should run these defers in reverse
   926  	// order of this list
   927  	openDefers []*openDeferInfo
   928  	// For open-coded defers, this is the beginning and end blocks of the last
   929  	// defer exit code that we have generated so far. We use these to share
   930  	// code between exits if the shareDeferExits option (disabled by default)
   931  	// is on.
   932  	lastDeferExit       *ssa.Block // Entry block of last defer exit code we generated
   933  	lastDeferFinalBlock *ssa.Block // Final block of last defer exit code we generated
   934  	lastDeferCount      int        // Number of defers encountered at that point
   935  
   936  	prevCall *ssa.Value // the previous call; use this to tie results to the call op.
   937  }
   938  
   939  type funcLine struct {
   940  	f    *obj.LSym
   941  	base *src.PosBase
   942  	line uint
   943  }
   944  
   945  type ssaLabel struct {
   946  	target         *ssa.Block // block identified by this label
   947  	breakTarget    *ssa.Block // block to break to in control flow node identified by this label
   948  	continueTarget *ssa.Block // block to continue to in control flow node identified by this label
   949  }
   950  
   951  // label returns the label associated with sym, creating it if necessary.
   952  func (s *state) label(sym *types.Sym) *ssaLabel {
   953  	lab := s.labels[sym.Name]
   954  	if lab == nil {
   955  		lab = new(ssaLabel)
   956  		s.labels[sym.Name] = lab
   957  	}
   958  	return lab
   959  }
   960  
   961  func (s *state) Logf(msg string, args ...interface{}) { s.f.Logf(msg, args...) }
   962  func (s *state) Log() bool                            { return s.f.Log() }
   963  func (s *state) Fatalf(msg string, args ...interface{}) {
   964  	s.f.Frontend().Fatalf(s.peekPos(), msg, args...)
   965  }
   966  func (s *state) Warnl(pos src.XPos, msg string, args ...interface{}) { s.f.Warnl(pos, msg, args...) }
   967  func (s *state) Debug_checknil() bool                                { return s.f.Frontend().Debug_checknil() }
   968  
   969  func ssaMarker(name string) *ir.Name {
   970  	return ir.NewNameAt(base.Pos, &types.Sym{Name: name}, nil)
   971  }
   972  
   973  var (
   974  	// marker node for the memory variable
   975  	memVar = ssaMarker("mem")
   976  
   977  	// marker nodes for temporary variables
   978  	ptrVar       = ssaMarker("ptr")
   979  	lenVar       = ssaMarker("len")
   980  	capVar       = ssaMarker("cap")
   981  	typVar       = ssaMarker("typ")
   982  	okVar        = ssaMarker("ok")
   983  	deferBitsVar = ssaMarker("deferBits")
   984  	hashVar      = ssaMarker("hash")
   985  )
   986  
   987  // startBlock sets the current block we're generating code in to b.
   988  func (s *state) startBlock(b *ssa.Block) {
   989  	if s.curBlock != nil {
   990  		s.Fatalf("starting block %v when block %v has not ended", b, s.curBlock)
   991  	}
   992  	s.curBlock = b
   993  	s.vars = map[ir.Node]*ssa.Value{}
   994  	clear(s.fwdVars)
   995  }
   996  
   997  // endBlock marks the end of generating code for the current block.
   998  // Returns the (former) current block. Returns nil if there is no current
   999  // block, i.e. if no code flows to the current execution point.
  1000  func (s *state) endBlock() *ssa.Block {
  1001  	b := s.curBlock
  1002  	if b == nil {
  1003  		return nil
  1004  	}
  1005  	for len(s.defvars) <= int(b.ID) {
  1006  		s.defvars = append(s.defvars, nil)
  1007  	}
  1008  	s.defvars[b.ID] = s.vars
  1009  	s.curBlock = nil
  1010  	s.vars = nil
  1011  	if b.LackingPos() {
  1012  		// Empty plain blocks get the line of their successor (handled after all blocks created),
  1013  		// except for increment blocks in For statements (handled in ssa conversion of OFOR),
  1014  		// and for blocks ending in GOTO/BREAK/CONTINUE.
  1015  		b.Pos = src.NoXPos
  1016  	} else {
  1017  		b.Pos = s.lastPos
  1018  	}
  1019  	return b
  1020  }
  1021  
  1022  // pushLine pushes a line number on the line number stack.
  1023  func (s *state) pushLine(line src.XPos) {
  1024  	if !line.IsKnown() {
  1025  		// the frontend may emit node with line number missing,
  1026  		// use the parent line number in this case.
  1027  		line = s.peekPos()
  1028  		if base.Flag.K != 0 {
  1029  			base.Warn("buildssa: unknown position (line 0)")
  1030  		}
  1031  	} else {
  1032  		s.lastPos = line
  1033  	}
  1034  
  1035  	s.line = append(s.line, line)
  1036  }
  1037  
  1038  // popLine pops the top of the line number stack.
  1039  func (s *state) popLine() {
  1040  	s.line = s.line[:len(s.line)-1]
  1041  }
  1042  
  1043  // peekPos peeks the top of the line number stack.
  1044  func (s *state) peekPos() src.XPos {
  1045  	return s.line[len(s.line)-1]
  1046  }
  1047  
  1048  // newValue0 adds a new value with no arguments to the current block.
  1049  func (s *state) newValue0(op ssa.Op, t *types.Type) *ssa.Value {
  1050  	return s.curBlock.NewValue0(s.peekPos(), op, t)
  1051  }
  1052  
  1053  // newValue0A adds a new value with no arguments and an aux value to the current block.
  1054  func (s *state) newValue0A(op ssa.Op, t *types.Type, aux ssa.Aux) *ssa.Value {
  1055  	return s.curBlock.NewValue0A(s.peekPos(), op, t, aux)
  1056  }
  1057  
  1058  // newValue0I adds a new value with no arguments and an auxint value to the current block.
  1059  func (s *state) newValue0I(op ssa.Op, t *types.Type, auxint int64) *ssa.Value {
  1060  	return s.curBlock.NewValue0I(s.peekPos(), op, t, auxint)
  1061  }
  1062  
  1063  // newValue1 adds a new value with one argument to the current block.
  1064  func (s *state) newValue1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1065  	return s.curBlock.NewValue1(s.peekPos(), op, t, arg)
  1066  }
  1067  
  1068  // newValue1A adds a new value with one argument and an aux value to the current block.
  1069  func (s *state) newValue1A(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value) *ssa.Value {
  1070  	return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
  1071  }
  1072  
  1073  // newValue1Apos adds a new value with one argument and an aux value to the current block.
  1074  // isStmt determines whether the created values may be a statement or not
  1075  // (i.e., false means never, yes means maybe).
  1076  func (s *state) newValue1Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value, isStmt bool) *ssa.Value {
  1077  	if isStmt {
  1078  		return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
  1079  	}
  1080  	return s.curBlock.NewValue1A(s.peekPos().WithNotStmt(), op, t, aux, arg)
  1081  }
  1082  
  1083  // newValue1I adds a new value with one argument and an auxint value to the current block.
  1084  func (s *state) newValue1I(op ssa.Op, t *types.Type, aux int64, arg *ssa.Value) *ssa.Value {
  1085  	return s.curBlock.NewValue1I(s.peekPos(), op, t, aux, arg)
  1086  }
  1087  
  1088  // newValue2 adds a new value with two arguments to the current block.
  1089  func (s *state) newValue2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1090  	return s.curBlock.NewValue2(s.peekPos(), op, t, arg0, arg1)
  1091  }
  1092  
  1093  // newValue2A adds a new value with two arguments and an aux value to the current block.
  1094  func (s *state) newValue2A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value) *ssa.Value {
  1095  	return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
  1096  }
  1097  
  1098  // newValue2Apos adds a new value with two arguments and an aux value to the current block.
  1099  // isStmt determines whether the created values may be a statement or not
  1100  // (i.e., false means never, yes means maybe).
  1101  func (s *state) newValue2Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value, isStmt bool) *ssa.Value {
  1102  	if isStmt {
  1103  		return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
  1104  	}
  1105  	return s.curBlock.NewValue2A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1)
  1106  }
  1107  
  1108  // newValue2I adds a new value with two arguments and an auxint value to the current block.
  1109  func (s *state) newValue2I(op ssa.Op, t *types.Type, aux int64, arg0, arg1 *ssa.Value) *ssa.Value {
  1110  	return s.curBlock.NewValue2I(s.peekPos(), op, t, aux, arg0, arg1)
  1111  }
  1112  
  1113  // newValue3 adds a new value with three arguments to the current block.
  1114  func (s *state) newValue3(op ssa.Op, t *types.Type, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1115  	return s.curBlock.NewValue3(s.peekPos(), op, t, arg0, arg1, arg2)
  1116  }
  1117  
  1118  // newValue3I adds a new value with three arguments and an auxint value to the current block.
  1119  func (s *state) newValue3I(op ssa.Op, t *types.Type, aux int64, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1120  	return s.curBlock.NewValue3I(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1121  }
  1122  
  1123  // newValue3A adds a new value with three arguments and an aux value to the current block.
  1124  func (s *state) newValue3A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
  1125  	return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1126  }
  1127  
  1128  // newValue3Apos adds a new value with three arguments and an aux value to the current block.
  1129  // isStmt determines whether the created values may be a statement or not
  1130  // (i.e., false means never, yes means maybe).
  1131  func (s *state) newValue3Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1, arg2 *ssa.Value, isStmt bool) *ssa.Value {
  1132  	if isStmt {
  1133  		return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
  1134  	}
  1135  	return s.curBlock.NewValue3A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1, arg2)
  1136  }
  1137  
  1138  // newValue4 adds a new value with four arguments to the current block.
  1139  func (s *state) newValue4(op ssa.Op, t *types.Type, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
  1140  	return s.curBlock.NewValue4(s.peekPos(), op, t, arg0, arg1, arg2, arg3)
  1141  }
  1142  
  1143  // newValue4I adds a new value with four arguments and an auxint value to the current block.
  1144  func (s *state) newValue4I(op ssa.Op, t *types.Type, aux int64, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
  1145  	return s.curBlock.NewValue4I(s.peekPos(), op, t, aux, arg0, arg1, arg2, arg3)
  1146  }
  1147  
  1148  func (s *state) entryBlock() *ssa.Block {
  1149  	b := s.f.Entry
  1150  	if base.Flag.N > 0 && s.curBlock != nil {
  1151  		// If optimizations are off, allocate in current block instead. Since with -N
  1152  		// we're not doing the CSE or tighten passes, putting lots of stuff in the
  1153  		// entry block leads to O(n^2) entries in the live value map during regalloc.
  1154  		// See issue 45897.
  1155  		b = s.curBlock
  1156  	}
  1157  	return b
  1158  }
  1159  
  1160  // entryNewValue0 adds a new value with no arguments to the entry block.
  1161  func (s *state) entryNewValue0(op ssa.Op, t *types.Type) *ssa.Value {
  1162  	return s.entryBlock().NewValue0(src.NoXPos, op, t)
  1163  }
  1164  
  1165  // entryNewValue0A adds a new value with no arguments and an aux value to the entry block.
  1166  func (s *state) entryNewValue0A(op ssa.Op, t *types.Type, aux ssa.Aux) *ssa.Value {
  1167  	return s.entryBlock().NewValue0A(src.NoXPos, op, t, aux)
  1168  }
  1169  
  1170  // entryNewValue1 adds a new value with one argument to the entry block.
  1171  func (s *state) entryNewValue1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1172  	return s.entryBlock().NewValue1(src.NoXPos, op, t, arg)
  1173  }
  1174  
  1175  // entryNewValue1I adds a new value with one argument and an auxint value to the entry block.
  1176  func (s *state) entryNewValue1I(op ssa.Op, t *types.Type, auxint int64, arg *ssa.Value) *ssa.Value {
  1177  	return s.entryBlock().NewValue1I(src.NoXPos, op, t, auxint, arg)
  1178  }
  1179  
  1180  // entryNewValue1A adds a new value with one argument and an aux value to the entry block.
  1181  func (s *state) entryNewValue1A(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value) *ssa.Value {
  1182  	return s.entryBlock().NewValue1A(src.NoXPos, op, t, aux, arg)
  1183  }
  1184  
  1185  // entryNewValue2 adds a new value with two arguments to the entry block.
  1186  func (s *state) entryNewValue2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1187  	return s.entryBlock().NewValue2(src.NoXPos, op, t, arg0, arg1)
  1188  }
  1189  
  1190  // entryNewValue2A adds a new value with two arguments and an aux value to the entry block.
  1191  func (s *state) entryNewValue2A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value) *ssa.Value {
  1192  	return s.entryBlock().NewValue2A(src.NoXPos, op, t, aux, arg0, arg1)
  1193  }
  1194  
  1195  // const* routines add a new const value to the entry block.
  1196  func (s *state) constSlice(t *types.Type) *ssa.Value {
  1197  	return s.f.ConstSlice(t)
  1198  }
  1199  func (s *state) constInterface(t *types.Type) *ssa.Value {
  1200  	return s.f.ConstInterface(t)
  1201  }
  1202  func (s *state) constNil(t *types.Type) *ssa.Value { return s.f.ConstNil(t) }
  1203  func (s *state) constEmptyString(t *types.Type) *ssa.Value {
  1204  	return s.f.ConstEmptyString(t)
  1205  }
  1206  func (s *state) constBool(c bool) *ssa.Value {
  1207  	return s.f.ConstBool(types.Types[types.TBOOL], c)
  1208  }
  1209  func (s *state) constInt8(t *types.Type, c int8) *ssa.Value {
  1210  	return s.f.ConstInt8(t, c)
  1211  }
  1212  func (s *state) constInt16(t *types.Type, c int16) *ssa.Value {
  1213  	return s.f.ConstInt16(t, c)
  1214  }
  1215  func (s *state) constInt32(t *types.Type, c int32) *ssa.Value {
  1216  	return s.f.ConstInt32(t, c)
  1217  }
  1218  func (s *state) constInt64(t *types.Type, c int64) *ssa.Value {
  1219  	return s.f.ConstInt64(t, c)
  1220  }
  1221  func (s *state) constFloat32(t *types.Type, c float64) *ssa.Value {
  1222  	return s.f.ConstFloat32(t, c)
  1223  }
  1224  func (s *state) constFloat64(t *types.Type, c float64) *ssa.Value {
  1225  	return s.f.ConstFloat64(t, c)
  1226  }
  1227  func (s *state) constInt(t *types.Type, c int64) *ssa.Value {
  1228  	if s.config.PtrSize == 8 {
  1229  		return s.constInt64(t, c)
  1230  	}
  1231  	if int64(int32(c)) != c {
  1232  		s.Fatalf("integer constant too big %d", c)
  1233  	}
  1234  	return s.constInt32(t, int32(c))
  1235  }
  1236  func (s *state) constOffPtrSP(t *types.Type, c int64) *ssa.Value {
  1237  	return s.f.ConstOffPtrSP(t, c, s.sp)
  1238  }
  1239  
  1240  // newValueOrSfCall* are wrappers around newValue*, which may create a call to a
  1241  // soft-float runtime function instead (when emitting soft-float code).
  1242  func (s *state) newValueOrSfCall1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
  1243  	if s.softFloat {
  1244  		if c, ok := s.sfcall(op, arg); ok {
  1245  			return c
  1246  		}
  1247  	}
  1248  	return s.newValue1(op, t, arg)
  1249  }
  1250  func (s *state) newValueOrSfCall2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
  1251  	if s.softFloat {
  1252  		if c, ok := s.sfcall(op, arg0, arg1); ok {
  1253  			return c
  1254  		}
  1255  	}
  1256  	return s.newValue2(op, t, arg0, arg1)
  1257  }
  1258  
  1259  type instrumentKind uint8
  1260  
  1261  const (
  1262  	instrumentRead = iota
  1263  	instrumentWrite
  1264  	instrumentMove
  1265  )
  1266  
  1267  func (s *state) instrument(t *types.Type, addr *ssa.Value, kind instrumentKind) {
  1268  	s.instrument2(t, addr, nil, kind)
  1269  }
  1270  
  1271  // instrumentFields instruments a read/write operation on addr.
  1272  // If it is instrumenting for MSAN or ASAN and t is a struct type, it instruments
  1273  // operation for each field, instead of for the whole struct.
  1274  func (s *state) instrumentFields(t *types.Type, addr *ssa.Value, kind instrumentKind) {
  1275  	if !(base.Flag.MSan || base.Flag.ASan) || !t.IsStruct() {
  1276  		s.instrument(t, addr, kind)
  1277  		return
  1278  	}
  1279  	for _, f := range t.Fields() {
  1280  		if f.Sym.IsBlank() {
  1281  			continue
  1282  		}
  1283  		offptr := s.newValue1I(ssa.OpOffPtr, types.NewPtr(f.Type), f.Offset, addr)
  1284  		s.instrumentFields(f.Type, offptr, kind)
  1285  	}
  1286  }
  1287  
  1288  func (s *state) instrumentMove(t *types.Type, dst, src *ssa.Value) {
  1289  	if base.Flag.MSan {
  1290  		s.instrument2(t, dst, src, instrumentMove)
  1291  	} else {
  1292  		s.instrument(t, src, instrumentRead)
  1293  		s.instrument(t, dst, instrumentWrite)
  1294  	}
  1295  }
  1296  
  1297  func (s *state) instrument2(t *types.Type, addr, addr2 *ssa.Value, kind instrumentKind) {
  1298  	if !s.instrumentMemory {
  1299  		return
  1300  	}
  1301  
  1302  	w := t.Size()
  1303  	if w == 0 {
  1304  		return // can't race on zero-sized things
  1305  	}
  1306  
  1307  	if ssa.IsSanitizerSafeAddr(addr) {
  1308  		return
  1309  	}
  1310  
  1311  	var fn *obj.LSym
  1312  	needWidth := false
  1313  
  1314  	if addr2 != nil && kind != instrumentMove {
  1315  		panic("instrument2: non-nil addr2 for non-move instrumentation")
  1316  	}
  1317  
  1318  	if base.Flag.MSan {
  1319  		switch kind {
  1320  		case instrumentRead:
  1321  			fn = ir.Syms.Msanread
  1322  		case instrumentWrite:
  1323  			fn = ir.Syms.Msanwrite
  1324  		case instrumentMove:
  1325  			fn = ir.Syms.Msanmove
  1326  		default:
  1327  			panic("unreachable")
  1328  		}
  1329  		needWidth = true
  1330  	} else if base.Flag.Race && t.NumComponents(types.CountBlankFields) > 1 {
  1331  		// for composite objects we have to write every address
  1332  		// because a write might happen to any subobject.
  1333  		// composites with only one element don't have subobjects, though.
  1334  		switch kind {
  1335  		case instrumentRead:
  1336  			fn = ir.Syms.Racereadrange
  1337  		case instrumentWrite:
  1338  			fn = ir.Syms.Racewriterange
  1339  		default:
  1340  			panic("unreachable")
  1341  		}
  1342  		needWidth = true
  1343  	} else if base.Flag.Race {
  1344  		// for non-composite objects we can write just the start
  1345  		// address, as any write must write the first byte.
  1346  		switch kind {
  1347  		case instrumentRead:
  1348  			fn = ir.Syms.Raceread
  1349  		case instrumentWrite:
  1350  			fn = ir.Syms.Racewrite
  1351  		default:
  1352  			panic("unreachable")
  1353  		}
  1354  	} else if base.Flag.ASan {
  1355  		switch kind {
  1356  		case instrumentRead:
  1357  			fn = ir.Syms.Asanread
  1358  		case instrumentWrite:
  1359  			fn = ir.Syms.Asanwrite
  1360  		default:
  1361  			panic("unreachable")
  1362  		}
  1363  		needWidth = true
  1364  	} else {
  1365  		panic("unreachable")
  1366  	}
  1367  
  1368  	args := []*ssa.Value{addr}
  1369  	if addr2 != nil {
  1370  		args = append(args, addr2)
  1371  	}
  1372  	if needWidth {
  1373  		args = append(args, s.constInt(types.Types[types.TUINTPTR], w))
  1374  	}
  1375  	s.rtcall(fn, true, nil, args...)
  1376  }
  1377  
  1378  func (s *state) load(t *types.Type, src *ssa.Value) *ssa.Value {
  1379  	s.instrumentFields(t, src, instrumentRead)
  1380  	return s.rawLoad(t, src)
  1381  }
  1382  
  1383  func (s *state) rawLoad(t *types.Type, src *ssa.Value) *ssa.Value {
  1384  	return s.newValue2(ssa.OpLoad, t, src, s.mem())
  1385  }
  1386  
  1387  func (s *state) store(t *types.Type, dst, val *ssa.Value) {
  1388  	s.vars[memVar] = s.newValue3A(ssa.OpStore, types.TypeMem, t, dst, val, s.mem())
  1389  }
  1390  
  1391  func (s *state) zero(t *types.Type, dst *ssa.Value) {
  1392  	s.instrument(t, dst, instrumentWrite)
  1393  	store := s.newValue2I(ssa.OpZero, types.TypeMem, t.Size(), dst, s.mem())
  1394  	store.Aux = t
  1395  	s.vars[memVar] = store
  1396  }
  1397  
  1398  func (s *state) move(t *types.Type, dst, src *ssa.Value) {
  1399  	s.moveWhichMayOverlap(t, dst, src, false)
  1400  }
  1401  func (s *state) moveWhichMayOverlap(t *types.Type, dst, src *ssa.Value, mayOverlap bool) {
  1402  	s.instrumentMove(t, dst, src)
  1403  	if mayOverlap && t.IsArray() && t.NumElem() > 1 && !ssa.IsInlinableMemmove(dst, src, t.Size(), s.f.Config) {
  1404  		// Normally, when moving Go values of type T from one location to another,
  1405  		// we don't need to worry about partial overlaps. The two Ts must either be
  1406  		// in disjoint (nonoverlapping) memory or in exactly the same location.
  1407  		// There are 2 cases where this isn't true:
  1408  		//  1) Using unsafe you can arrange partial overlaps.
  1409  		//  2) Since Go 1.17, you can use a cast from a slice to a ptr-to-array.
  1410  		//     https://go.dev/ref/spec#Conversions_from_slice_to_array_pointer
  1411  		//     This feature can be used to construct partial overlaps of array types.
  1412  		//       var a [3]int
  1413  		//       p := (*[2]int)(a[:])
  1414  		//       q := (*[2]int)(a[1:])
  1415  		//       *p = *q
  1416  		// We don't care about solving 1. Or at least, we haven't historically
  1417  		// and no one has complained.
  1418  		// For 2, we need to ensure that if there might be partial overlap,
  1419  		// then we can't use OpMove; we must use memmove instead.
  1420  		// (memmove handles partial overlap by copying in the correct
  1421  		// direction. OpMove does not.)
  1422  		//
  1423  		// Note that we have to be careful here not to introduce a call when
  1424  		// we're marshaling arguments to a call or unmarshaling results from a call.
  1425  		// Cases where this is happening must pass mayOverlap to false.
  1426  		// (Currently this only happens when unmarshaling results of a call.)
  1427  		if t.HasPointers() {
  1428  			s.rtcall(ir.Syms.Typedmemmove, true, nil, s.reflectType(t), dst, src)
  1429  			// We would have otherwise implemented this move with straightline code,
  1430  			// including a write barrier. Pretend we issue a write barrier here,
  1431  			// so that the write barrier tests work. (Otherwise they'd need to know
  1432  			// the details of IsInlineableMemmove.)
  1433  			s.curfn.SetWBPos(s.peekPos())
  1434  		} else {
  1435  			s.rtcall(ir.Syms.Memmove, true, nil, dst, src, s.constInt(types.Types[types.TUINTPTR], t.Size()))
  1436  		}
  1437  		ssa.LogLargeCopy(s.f.Name, s.peekPos(), t.Size())
  1438  		return
  1439  	}
  1440  	store := s.newValue3I(ssa.OpMove, types.TypeMem, t.Size(), dst, src, s.mem())
  1441  	store.Aux = t
  1442  	s.vars[memVar] = store
  1443  }
  1444  
  1445  // stmtList converts the statement list n to SSA and adds it to s.
  1446  func (s *state) stmtList(l ir.Nodes) {
  1447  	for _, n := range l {
  1448  		s.stmt(n)
  1449  	}
  1450  }
  1451  
  1452  // stmt converts the statement n to SSA and adds it to s.
  1453  func (s *state) stmt(n ir.Node) {
  1454  	s.pushLine(n.Pos())
  1455  	defer s.popLine()
  1456  
  1457  	// If s.curBlock is nil, and n isn't a label (which might have an associated goto somewhere),
  1458  	// then this code is dead. Stop here.
  1459  	if s.curBlock == nil && n.Op() != ir.OLABEL {
  1460  		return
  1461  	}
  1462  
  1463  	s.stmtList(n.Init())
  1464  	switch n.Op() {
  1465  
  1466  	case ir.OBLOCK:
  1467  		n := n.(*ir.BlockStmt)
  1468  		s.stmtList(n.List)
  1469  
  1470  	case ir.OFALL: // no-op
  1471  
  1472  	// Expression statements
  1473  	case ir.OCALLFUNC:
  1474  		n := n.(*ir.CallExpr)
  1475  		if ir.IsIntrinsicCall(n) {
  1476  			s.intrinsicCall(n)
  1477  			return
  1478  		}
  1479  		fallthrough
  1480  
  1481  	case ir.OCALLINTER:
  1482  		n := n.(*ir.CallExpr)
  1483  		s.callResult(n, callNormal)
  1484  		if n.Op() == ir.OCALLFUNC && n.Fun.Op() == ir.ONAME && n.Fun.(*ir.Name).Class == ir.PFUNC {
  1485  			if fn := n.Fun.Sym().Name; base.Flag.CompilingRuntime && fn == "throw" ||
  1486  				n.Fun.Sym().Pkg == ir.Pkgs.Runtime &&
  1487  					(fn == "throwinit" || fn == "gopanic" || fn == "panicwrap" || fn == "block" ||
  1488  						fn == "panicmakeslicelen" || fn == "panicmakeslicecap" || fn == "panicunsafeslicelen" ||
  1489  						fn == "panicunsafeslicenilptr" || fn == "panicunsafestringlen" || fn == "panicunsafestringnilptr" ||
  1490  						fn == "panicrangestate") {
  1491  				m := s.mem()
  1492  				b := s.endBlock()
  1493  				b.Kind = ssa.BlockExit
  1494  				b.SetControl(m)
  1495  				// TODO: never rewrite OPANIC to OCALLFUNC in the
  1496  				// first place. Need to wait until all backends
  1497  				// go through SSA.
  1498  			}
  1499  		}
  1500  	case ir.ODEFER:
  1501  		n := n.(*ir.GoDeferStmt)
  1502  		if base.Debug.Defer > 0 {
  1503  			var defertype string
  1504  			if s.hasOpenDefers {
  1505  				defertype = "open-coded"
  1506  			} else if n.Esc() == ir.EscNever {
  1507  				defertype = "stack-allocated"
  1508  			} else {
  1509  				defertype = "heap-allocated"
  1510  			}
  1511  			base.WarnfAt(n.Pos(), "%s defer", defertype)
  1512  		}
  1513  		if s.hasOpenDefers {
  1514  			s.openDeferRecord(n.Call.(*ir.CallExpr))
  1515  		} else {
  1516  			d := callDefer
  1517  			if n.Esc() == ir.EscNever && n.DeferAt == nil {
  1518  				d = callDeferStack
  1519  			}
  1520  			s.call(n.Call.(*ir.CallExpr), d, false, n.DeferAt)
  1521  		}
  1522  	case ir.OGO:
  1523  		n := n.(*ir.GoDeferStmt)
  1524  		s.callResult(n.Call.(*ir.CallExpr), callGo)
  1525  
  1526  	case ir.OAS2DOTTYPE:
  1527  		n := n.(*ir.AssignListStmt)
  1528  		var res, resok *ssa.Value
  1529  		if n.Rhs[0].Op() == ir.ODOTTYPE2 {
  1530  			res, resok = s.dottype(n.Rhs[0].(*ir.TypeAssertExpr), true)
  1531  		} else {
  1532  			res, resok = s.dynamicDottype(n.Rhs[0].(*ir.DynamicTypeAssertExpr), true)
  1533  		}
  1534  		deref := false
  1535  		if !ssa.CanSSA(n.Rhs[0].Type()) {
  1536  			if res.Op != ssa.OpLoad {
  1537  				s.Fatalf("dottype of non-load")
  1538  			}
  1539  			mem := s.mem()
  1540  			if res.Args[1] != mem {
  1541  				s.Fatalf("memory no longer live from 2-result dottype load")
  1542  			}
  1543  			deref = true
  1544  			res = res.Args[0]
  1545  		}
  1546  		s.assign(n.Lhs[0], res, deref, 0)
  1547  		s.assign(n.Lhs[1], resok, false, 0)
  1548  		return
  1549  
  1550  	case ir.OAS2FUNC:
  1551  		// We come here only when it is an intrinsic call returning two values.
  1552  		n := n.(*ir.AssignListStmt)
  1553  		call := n.Rhs[0].(*ir.CallExpr)
  1554  		if !ir.IsIntrinsicCall(call) {
  1555  			s.Fatalf("non-intrinsic AS2FUNC not expanded %v", call)
  1556  		}
  1557  		v := s.intrinsicCall(call)
  1558  		v1 := s.newValue1(ssa.OpSelect0, n.Lhs[0].Type(), v)
  1559  		v2 := s.newValue1(ssa.OpSelect1, n.Lhs[1].Type(), v)
  1560  		s.assign(n.Lhs[0], v1, false, 0)
  1561  		s.assign(n.Lhs[1], v2, false, 0)
  1562  		return
  1563  
  1564  	case ir.ODCL:
  1565  		n := n.(*ir.Decl)
  1566  		if v := n.X; v.Esc() == ir.EscHeap {
  1567  			s.newHeapaddr(v)
  1568  		}
  1569  
  1570  	case ir.OLABEL:
  1571  		n := n.(*ir.LabelStmt)
  1572  		sym := n.Label
  1573  		if sym.IsBlank() {
  1574  			// Nothing to do because the label isn't targetable. See issue 52278.
  1575  			break
  1576  		}
  1577  		lab := s.label(sym)
  1578  
  1579  		// The label might already have a target block via a goto.
  1580  		if lab.target == nil {
  1581  			lab.target = s.f.NewBlock(ssa.BlockPlain)
  1582  		}
  1583  
  1584  		// Go to that label.
  1585  		// (We pretend "label:" is preceded by "goto label", unless the predecessor is unreachable.)
  1586  		if s.curBlock != nil {
  1587  			b := s.endBlock()
  1588  			b.AddEdgeTo(lab.target)
  1589  		}
  1590  		s.startBlock(lab.target)
  1591  
  1592  	case ir.OGOTO:
  1593  		n := n.(*ir.BranchStmt)
  1594  		sym := n.Label
  1595  
  1596  		lab := s.label(sym)
  1597  		if lab.target == nil {
  1598  			lab.target = s.f.NewBlock(ssa.BlockPlain)
  1599  		}
  1600  
  1601  		b := s.endBlock()
  1602  		b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
  1603  		b.AddEdgeTo(lab.target)
  1604  
  1605  	case ir.OAS:
  1606  		n := n.(*ir.AssignStmt)
  1607  		if n.X == n.Y && n.X.Op() == ir.ONAME {
  1608  			// An x=x assignment. No point in doing anything
  1609  			// here. In addition, skipping this assignment
  1610  			// prevents generating:
  1611  			//   VARDEF x
  1612  			//   COPY x -> x
  1613  			// which is bad because x is incorrectly considered
  1614  			// dead before the vardef. See issue #14904.
  1615  			return
  1616  		}
  1617  
  1618  		// mayOverlap keeps track of whether the LHS and RHS might
  1619  		// refer to partially overlapping memory. Partial overlapping can
  1620  		// only happen for arrays, see the comment in moveWhichMayOverlap.
  1621  		//
  1622  		// If both sides of the assignment are not dereferences, then partial
  1623  		// overlap can't happen. Partial overlap can only occur only when the
  1624  		// arrays referenced are strictly smaller parts of the same base array.
  1625  		// If one side of the assignment is a full array, then partial overlap
  1626  		// can't happen. (The arrays are either disjoint or identical.)
  1627  		mayOverlap := n.X.Op() == ir.ODEREF && (n.Y != nil && n.Y.Op() == ir.ODEREF)
  1628  		if n.Y != nil && n.Y.Op() == ir.ODEREF {
  1629  			p := n.Y.(*ir.StarExpr).X
  1630  			for p.Op() == ir.OCONVNOP {
  1631  				p = p.(*ir.ConvExpr).X
  1632  			}
  1633  			if p.Op() == ir.OSPTR && p.(*ir.UnaryExpr).X.Type().IsString() {
  1634  				// Pointer fields of strings point to unmodifiable memory.
  1635  				// That memory can't overlap with the memory being written.
  1636  				mayOverlap = false
  1637  			}
  1638  		}
  1639  
  1640  		// Evaluate RHS.
  1641  		rhs := n.Y
  1642  		if rhs != nil {
  1643  			switch rhs.Op() {
  1644  			case ir.OSTRUCTLIT, ir.OARRAYLIT, ir.OSLICELIT:
  1645  				// All literals with nonzero fields have already been
  1646  				// rewritten during walk. Any that remain are just T{}
  1647  				// or equivalents. Use the zero value.
  1648  				if !ir.IsZero(rhs) {
  1649  					s.Fatalf("literal with nonzero value in SSA: %v", rhs)
  1650  				}
  1651  				rhs = nil
  1652  			case ir.OAPPEND:
  1653  				rhs := rhs.(*ir.CallExpr)
  1654  				// Check whether we're writing the result of an append back to the same slice.
  1655  				// If so, we handle it specially to avoid write barriers on the fast
  1656  				// (non-growth) path.
  1657  				if !ir.SameSafeExpr(n.X, rhs.Args[0]) || base.Flag.N != 0 {
  1658  					break
  1659  				}
  1660  				// If the slice can be SSA'd, it'll be on the stack,
  1661  				// so there will be no write barriers,
  1662  				// so there's no need to attempt to prevent them.
  1663  				if s.canSSA(n.X) {
  1664  					if base.Debug.Append > 0 { // replicating old diagnostic message
  1665  						base.WarnfAt(n.Pos(), "append: len-only update (in local slice)")
  1666  					}
  1667  					break
  1668  				}
  1669  				if base.Debug.Append > 0 {
  1670  					base.WarnfAt(n.Pos(), "append: len-only update")
  1671  				}
  1672  				s.append(rhs, true)
  1673  				return
  1674  			}
  1675  		}
  1676  
  1677  		if ir.IsBlank(n.X) {
  1678  			// _ = rhs
  1679  			// Just evaluate rhs for side-effects.
  1680  			if rhs != nil {
  1681  				s.expr(rhs)
  1682  			}
  1683  			return
  1684  		}
  1685  
  1686  		var t *types.Type
  1687  		if n.Y != nil {
  1688  			t = n.Y.Type()
  1689  		} else {
  1690  			t = n.X.Type()
  1691  		}
  1692  
  1693  		var r *ssa.Value
  1694  		deref := !ssa.CanSSA(t)
  1695  		if deref {
  1696  			if rhs == nil {
  1697  				r = nil // Signal assign to use OpZero.
  1698  			} else {
  1699  				r = s.addr(rhs)
  1700  			}
  1701  		} else {
  1702  			if rhs == nil {
  1703  				r = s.zeroVal(t)
  1704  			} else {
  1705  				r = s.expr(rhs)
  1706  			}
  1707  		}
  1708  
  1709  		var skip skipMask
  1710  		if rhs != nil && (rhs.Op() == ir.OSLICE || rhs.Op() == ir.OSLICE3 || rhs.Op() == ir.OSLICESTR) && ir.SameSafeExpr(rhs.(*ir.SliceExpr).X, n.X) {
  1711  			// We're assigning a slicing operation back to its source.
  1712  			// Don't write back fields we aren't changing. See issue #14855.
  1713  			rhs := rhs.(*ir.SliceExpr)
  1714  			i, j, k := rhs.Low, rhs.High, rhs.Max
  1715  			if i != nil && (i.Op() == ir.OLITERAL && i.Val().Kind() == constant.Int && ir.Int64Val(i) == 0) {
  1716  				// [0:...] is the same as [:...]
  1717  				i = nil
  1718  			}
  1719  			// TODO: detect defaults for len/cap also.
  1720  			// Currently doesn't really work because (*p)[:len(*p)] appears here as:
  1721  			//    tmp = len(*p)
  1722  			//    (*p)[:tmp]
  1723  			// if j != nil && (j.Op == OLEN && SameSafeExpr(j.Left, n.Left)) {
  1724  			//      j = nil
  1725  			// }
  1726  			// if k != nil && (k.Op == OCAP && SameSafeExpr(k.Left, n.Left)) {
  1727  			//      k = nil
  1728  			// }
  1729  			if i == nil {
  1730  				skip |= skipPtr
  1731  				if j == nil {
  1732  					skip |= skipLen
  1733  				}
  1734  				if k == nil {
  1735  					skip |= skipCap
  1736  				}
  1737  			}
  1738  		}
  1739  
  1740  		s.assignWhichMayOverlap(n.X, r, deref, skip, mayOverlap)
  1741  
  1742  	case ir.OIF:
  1743  		n := n.(*ir.IfStmt)
  1744  		if ir.IsConst(n.Cond, constant.Bool) {
  1745  			s.stmtList(n.Cond.Init())
  1746  			if ir.BoolVal(n.Cond) {
  1747  				s.stmtList(n.Body)
  1748  			} else {
  1749  				s.stmtList(n.Else)
  1750  			}
  1751  			break
  1752  		}
  1753  
  1754  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  1755  		var likely int8
  1756  		if n.Likely {
  1757  			likely = 1
  1758  		}
  1759  		var bThen *ssa.Block
  1760  		if len(n.Body) != 0 {
  1761  			bThen = s.f.NewBlock(ssa.BlockPlain)
  1762  		} else {
  1763  			bThen = bEnd
  1764  		}
  1765  		var bElse *ssa.Block
  1766  		if len(n.Else) != 0 {
  1767  			bElse = s.f.NewBlock(ssa.BlockPlain)
  1768  		} else {
  1769  			bElse = bEnd
  1770  		}
  1771  		s.condBranch(n.Cond, bThen, bElse, likely)
  1772  
  1773  		if len(n.Body) != 0 {
  1774  			s.startBlock(bThen)
  1775  			s.stmtList(n.Body)
  1776  			if b := s.endBlock(); b != nil {
  1777  				b.AddEdgeTo(bEnd)
  1778  			}
  1779  		}
  1780  		if len(n.Else) != 0 {
  1781  			s.startBlock(bElse)
  1782  			s.stmtList(n.Else)
  1783  			if b := s.endBlock(); b != nil {
  1784  				b.AddEdgeTo(bEnd)
  1785  			}
  1786  		}
  1787  		s.startBlock(bEnd)
  1788  
  1789  	case ir.ORETURN:
  1790  		n := n.(*ir.ReturnStmt)
  1791  		s.stmtList(n.Results)
  1792  		b := s.exit()
  1793  		b.Pos = s.lastPos.WithIsStmt()
  1794  
  1795  	case ir.OTAILCALL:
  1796  		n := n.(*ir.TailCallStmt)
  1797  		s.callResult(n.Call, callTail)
  1798  		call := s.mem()
  1799  		b := s.endBlock()
  1800  		b.Kind = ssa.BlockRetJmp // could use BlockExit. BlockRetJmp is mostly for clarity.
  1801  		b.SetControl(call)
  1802  
  1803  	case ir.OCONTINUE, ir.OBREAK:
  1804  		n := n.(*ir.BranchStmt)
  1805  		var to *ssa.Block
  1806  		if n.Label == nil {
  1807  			// plain break/continue
  1808  			switch n.Op() {
  1809  			case ir.OCONTINUE:
  1810  				to = s.continueTo
  1811  			case ir.OBREAK:
  1812  				to = s.breakTo
  1813  			}
  1814  		} else {
  1815  			// labeled break/continue; look up the target
  1816  			sym := n.Label
  1817  			lab := s.label(sym)
  1818  			switch n.Op() {
  1819  			case ir.OCONTINUE:
  1820  				to = lab.continueTarget
  1821  			case ir.OBREAK:
  1822  				to = lab.breakTarget
  1823  			}
  1824  		}
  1825  
  1826  		b := s.endBlock()
  1827  		b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
  1828  		b.AddEdgeTo(to)
  1829  
  1830  	case ir.OFOR:
  1831  		// OFOR: for Ninit; Left; Right { Nbody }
  1832  		// cond (Left); body (Nbody); incr (Right)
  1833  		n := n.(*ir.ForStmt)
  1834  		base.Assert(!n.DistinctVars) // Should all be rewritten before escape analysis
  1835  		bCond := s.f.NewBlock(ssa.BlockPlain)
  1836  		bBody := s.f.NewBlock(ssa.BlockPlain)
  1837  		bIncr := s.f.NewBlock(ssa.BlockPlain)
  1838  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  1839  
  1840  		// ensure empty for loops have correct position; issue #30167
  1841  		bBody.Pos = n.Pos()
  1842  
  1843  		// first, jump to condition test
  1844  		b := s.endBlock()
  1845  		b.AddEdgeTo(bCond)
  1846  
  1847  		// generate code to test condition
  1848  		s.startBlock(bCond)
  1849  		if n.Cond != nil {
  1850  			s.condBranch(n.Cond, bBody, bEnd, 1)
  1851  		} else {
  1852  			b := s.endBlock()
  1853  			b.Kind = ssa.BlockPlain
  1854  			b.AddEdgeTo(bBody)
  1855  		}
  1856  
  1857  		// set up for continue/break in body
  1858  		prevContinue := s.continueTo
  1859  		prevBreak := s.breakTo
  1860  		s.continueTo = bIncr
  1861  		s.breakTo = bEnd
  1862  		var lab *ssaLabel
  1863  		if sym := n.Label; sym != nil {
  1864  			// labeled for loop
  1865  			lab = s.label(sym)
  1866  			lab.continueTarget = bIncr
  1867  			lab.breakTarget = bEnd
  1868  		}
  1869  
  1870  		// generate body
  1871  		s.startBlock(bBody)
  1872  		s.stmtList(n.Body)
  1873  
  1874  		// tear down continue/break
  1875  		s.continueTo = prevContinue
  1876  		s.breakTo = prevBreak
  1877  		if lab != nil {
  1878  			lab.continueTarget = nil
  1879  			lab.breakTarget = nil
  1880  		}
  1881  
  1882  		// done with body, goto incr
  1883  		if b := s.endBlock(); b != nil {
  1884  			b.AddEdgeTo(bIncr)
  1885  		}
  1886  
  1887  		// generate incr
  1888  		s.startBlock(bIncr)
  1889  		if n.Post != nil {
  1890  			s.stmt(n.Post)
  1891  		}
  1892  		if b := s.endBlock(); b != nil {
  1893  			b.AddEdgeTo(bCond)
  1894  			// It can happen that bIncr ends in a block containing only VARKILL,
  1895  			// and that muddles the debugging experience.
  1896  			if b.Pos == src.NoXPos {
  1897  				b.Pos = bCond.Pos
  1898  			}
  1899  		}
  1900  
  1901  		s.startBlock(bEnd)
  1902  
  1903  	case ir.OSWITCH, ir.OSELECT:
  1904  		// These have been mostly rewritten by the front end into their Nbody fields.
  1905  		// Our main task is to correctly hook up any break statements.
  1906  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  1907  
  1908  		prevBreak := s.breakTo
  1909  		s.breakTo = bEnd
  1910  		var sym *types.Sym
  1911  		var body ir.Nodes
  1912  		if n.Op() == ir.OSWITCH {
  1913  			n := n.(*ir.SwitchStmt)
  1914  			sym = n.Label
  1915  			body = n.Compiled
  1916  		} else {
  1917  			n := n.(*ir.SelectStmt)
  1918  			sym = n.Label
  1919  			body = n.Compiled
  1920  		}
  1921  
  1922  		var lab *ssaLabel
  1923  		if sym != nil {
  1924  			// labeled
  1925  			lab = s.label(sym)
  1926  			lab.breakTarget = bEnd
  1927  		}
  1928  
  1929  		// generate body code
  1930  		s.stmtList(body)
  1931  
  1932  		s.breakTo = prevBreak
  1933  		if lab != nil {
  1934  			lab.breakTarget = nil
  1935  		}
  1936  
  1937  		// walk adds explicit OBREAK nodes to the end of all reachable code paths.
  1938  		// If we still have a current block here, then mark it unreachable.
  1939  		if s.curBlock != nil {
  1940  			m := s.mem()
  1941  			b := s.endBlock()
  1942  			b.Kind = ssa.BlockExit
  1943  			b.SetControl(m)
  1944  		}
  1945  		s.startBlock(bEnd)
  1946  
  1947  	case ir.OJUMPTABLE:
  1948  		n := n.(*ir.JumpTableStmt)
  1949  
  1950  		// Make blocks we'll need.
  1951  		jt := s.f.NewBlock(ssa.BlockJumpTable)
  1952  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  1953  
  1954  		// The only thing that needs evaluating is the index we're looking up.
  1955  		idx := s.expr(n.Idx)
  1956  		unsigned := idx.Type.IsUnsigned()
  1957  
  1958  		// Extend so we can do everything in uintptr arithmetic.
  1959  		t := types.Types[types.TUINTPTR]
  1960  		idx = s.conv(nil, idx, idx.Type, t)
  1961  
  1962  		// The ending condition for the current block decides whether we'll use
  1963  		// the jump table at all.
  1964  		// We check that min <= idx <= max and jump around the jump table
  1965  		// if that test fails.
  1966  		// We implement min <= idx <= max with 0 <= idx-min <= max-min, because
  1967  		// we'll need idx-min anyway as the control value for the jump table.
  1968  		var min, max uint64
  1969  		if unsigned {
  1970  			min, _ = constant.Uint64Val(n.Cases[0])
  1971  			max, _ = constant.Uint64Val(n.Cases[len(n.Cases)-1])
  1972  		} else {
  1973  			mn, _ := constant.Int64Val(n.Cases[0])
  1974  			mx, _ := constant.Int64Val(n.Cases[len(n.Cases)-1])
  1975  			min = uint64(mn)
  1976  			max = uint64(mx)
  1977  		}
  1978  		// Compare idx-min with max-min, to see if we can use the jump table.
  1979  		idx = s.newValue2(s.ssaOp(ir.OSUB, t), t, idx, s.uintptrConstant(min))
  1980  		width := s.uintptrConstant(max - min)
  1981  		cmp := s.newValue2(s.ssaOp(ir.OLE, t), types.Types[types.TBOOL], idx, width)
  1982  		b := s.endBlock()
  1983  		b.Kind = ssa.BlockIf
  1984  		b.SetControl(cmp)
  1985  		b.AddEdgeTo(jt)             // in range - use jump table
  1986  		b.AddEdgeTo(bEnd)           // out of range - no case in the jump table will trigger
  1987  		b.Likely = ssa.BranchLikely // TODO: assumes missing the table entirely is unlikely. True?
  1988  
  1989  		// Build jump table block.
  1990  		s.startBlock(jt)
  1991  		jt.Pos = n.Pos()
  1992  		if base.Flag.Cfg.SpectreIndex {
  1993  			idx = s.newValue2(ssa.OpSpectreSliceIndex, t, idx, width)
  1994  		}
  1995  		jt.SetControl(idx)
  1996  
  1997  		// Figure out where we should go for each index in the table.
  1998  		table := make([]*ssa.Block, max-min+1)
  1999  		for i := range table {
  2000  			table[i] = bEnd // default target
  2001  		}
  2002  		for i := range n.Targets {
  2003  			c := n.Cases[i]
  2004  			lab := s.label(n.Targets[i])
  2005  			if lab.target == nil {
  2006  				lab.target = s.f.NewBlock(ssa.BlockPlain)
  2007  			}
  2008  			var val uint64
  2009  			if unsigned {
  2010  				val, _ = constant.Uint64Val(c)
  2011  			} else {
  2012  				vl, _ := constant.Int64Val(c)
  2013  				val = uint64(vl)
  2014  			}
  2015  			// Overwrite the default target.
  2016  			table[val-min] = lab.target
  2017  		}
  2018  		for _, t := range table {
  2019  			jt.AddEdgeTo(t)
  2020  		}
  2021  		s.endBlock()
  2022  
  2023  		s.startBlock(bEnd)
  2024  
  2025  	case ir.OINTERFACESWITCH:
  2026  		n := n.(*ir.InterfaceSwitchStmt)
  2027  		typs := s.f.Config.Types
  2028  
  2029  		t := s.expr(n.RuntimeType)
  2030  		h := s.expr(n.Hash)
  2031  		d := s.newValue1A(ssa.OpAddr, typs.BytePtr, n.Descriptor, s.sb)
  2032  
  2033  		// Check the cache first.
  2034  		var merge *ssa.Block
  2035  		if base.Flag.N == 0 && rtabi.UseInterfaceSwitchCache(Arch.LinkArch.Name) {
  2036  			// Note: we can only use the cache if we have the right atomic load instruction.
  2037  			// Double-check that here.
  2038  			if intrinsics.lookup(Arch.LinkArch.Arch, "internal/runtime/atomic", "Loadp") == nil {
  2039  				s.Fatalf("atomic load not available")
  2040  			}
  2041  			merge = s.f.NewBlock(ssa.BlockPlain)
  2042  			cacheHit := s.f.NewBlock(ssa.BlockPlain)
  2043  			cacheMiss := s.f.NewBlock(ssa.BlockPlain)
  2044  			loopHead := s.f.NewBlock(ssa.BlockPlain)
  2045  			loopBody := s.f.NewBlock(ssa.BlockPlain)
  2046  
  2047  			// Pick right size ops.
  2048  			var mul, and, add, zext ssa.Op
  2049  			if s.config.PtrSize == 4 {
  2050  				mul = ssa.OpMul32
  2051  				and = ssa.OpAnd32
  2052  				add = ssa.OpAdd32
  2053  				zext = ssa.OpCopy
  2054  			} else {
  2055  				mul = ssa.OpMul64
  2056  				and = ssa.OpAnd64
  2057  				add = ssa.OpAdd64
  2058  				zext = ssa.OpZeroExt32to64
  2059  			}
  2060  
  2061  			// Load cache pointer out of descriptor, with an atomic load so
  2062  			// we ensure that we see a fully written cache.
  2063  			atomicLoad := s.newValue2(ssa.OpAtomicLoadPtr, types.NewTuple(typs.BytePtr, types.TypeMem), d, s.mem())
  2064  			cache := s.newValue1(ssa.OpSelect0, typs.BytePtr, atomicLoad)
  2065  			s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, atomicLoad)
  2066  
  2067  			// Initialize hash variable.
  2068  			s.vars[hashVar] = s.newValue1(zext, typs.Uintptr, h)
  2069  
  2070  			// Load mask from cache.
  2071  			mask := s.newValue2(ssa.OpLoad, typs.Uintptr, cache, s.mem())
  2072  			// Jump to loop head.
  2073  			b := s.endBlock()
  2074  			b.AddEdgeTo(loopHead)
  2075  
  2076  			// At loop head, get pointer to the cache entry.
  2077  			//   e := &cache.Entries[hash&mask]
  2078  			s.startBlock(loopHead)
  2079  			entries := s.newValue2(ssa.OpAddPtr, typs.UintptrPtr, cache, s.uintptrConstant(uint64(s.config.PtrSize)))
  2080  			idx := s.newValue2(and, typs.Uintptr, s.variable(hashVar, typs.Uintptr), mask)
  2081  			idx = s.newValue2(mul, typs.Uintptr, idx, s.uintptrConstant(uint64(3*s.config.PtrSize)))
  2082  			e := s.newValue2(ssa.OpAddPtr, typs.UintptrPtr, entries, idx)
  2083  			//   hash++
  2084  			s.vars[hashVar] = s.newValue2(add, typs.Uintptr, s.variable(hashVar, typs.Uintptr), s.uintptrConstant(1))
  2085  
  2086  			// Look for a cache hit.
  2087  			//   if e.Typ == t { goto hit }
  2088  			eTyp := s.newValue2(ssa.OpLoad, typs.Uintptr, e, s.mem())
  2089  			cmp1 := s.newValue2(ssa.OpEqPtr, typs.Bool, t, eTyp)
  2090  			b = s.endBlock()
  2091  			b.Kind = ssa.BlockIf
  2092  			b.SetControl(cmp1)
  2093  			b.AddEdgeTo(cacheHit)
  2094  			b.AddEdgeTo(loopBody)
  2095  
  2096  			// Look for an empty entry, the tombstone for this hash table.
  2097  			//   if e.Typ == nil { goto miss }
  2098  			s.startBlock(loopBody)
  2099  			cmp2 := s.newValue2(ssa.OpEqPtr, typs.Bool, eTyp, s.constNil(typs.BytePtr))
  2100  			b = s.endBlock()
  2101  			b.Kind = ssa.BlockIf
  2102  			b.SetControl(cmp2)
  2103  			b.AddEdgeTo(cacheMiss)
  2104  			b.AddEdgeTo(loopHead)
  2105  
  2106  			// On a hit, load the data fields of the cache entry.
  2107  			//   Case = e.Case
  2108  			//   Itab = e.Itab
  2109  			s.startBlock(cacheHit)
  2110  			eCase := s.newValue2(ssa.OpLoad, typs.Int, s.newValue1I(ssa.OpOffPtr, typs.IntPtr, s.config.PtrSize, e), s.mem())
  2111  			eItab := s.newValue2(ssa.OpLoad, typs.BytePtr, s.newValue1I(ssa.OpOffPtr, typs.BytePtrPtr, 2*s.config.PtrSize, e), s.mem())
  2112  			s.assign(n.Case, eCase, false, 0)
  2113  			s.assign(n.Itab, eItab, false, 0)
  2114  			b = s.endBlock()
  2115  			b.AddEdgeTo(merge)
  2116  
  2117  			// On a miss, call into the runtime to get the answer.
  2118  			s.startBlock(cacheMiss)
  2119  		}
  2120  
  2121  		r := s.rtcall(ir.Syms.InterfaceSwitch, true, []*types.Type{typs.Int, typs.BytePtr}, d, t)
  2122  		s.assign(n.Case, r[0], false, 0)
  2123  		s.assign(n.Itab, r[1], false, 0)
  2124  
  2125  		if merge != nil {
  2126  			// Cache hits merge in here.
  2127  			b := s.endBlock()
  2128  			b.Kind = ssa.BlockPlain
  2129  			b.AddEdgeTo(merge)
  2130  			s.startBlock(merge)
  2131  		}
  2132  
  2133  	case ir.OCHECKNIL:
  2134  		n := n.(*ir.UnaryExpr)
  2135  		p := s.expr(n.X)
  2136  		_ = s.nilCheck(p)
  2137  		// TODO: check that throwing away the nilcheck result is ok.
  2138  
  2139  	case ir.OINLMARK:
  2140  		n := n.(*ir.InlineMarkStmt)
  2141  		s.newValue1I(ssa.OpInlMark, types.TypeVoid, n.Index, s.mem())
  2142  
  2143  	default:
  2144  		s.Fatalf("unhandled stmt %v", n.Op())
  2145  	}
  2146  }
  2147  
  2148  // If true, share as many open-coded defer exits as possible (with the downside of
  2149  // worse line-number information)
  2150  const shareDeferExits = false
  2151  
  2152  // exit processes any code that needs to be generated just before returning.
  2153  // It returns a BlockRet block that ends the control flow. Its control value
  2154  // will be set to the final memory state.
  2155  func (s *state) exit() *ssa.Block {
  2156  	if s.hasdefer {
  2157  		if s.hasOpenDefers {
  2158  			if shareDeferExits && s.lastDeferExit != nil && len(s.openDefers) == s.lastDeferCount {
  2159  				if s.curBlock.Kind != ssa.BlockPlain {
  2160  					panic("Block for an exit should be BlockPlain")
  2161  				}
  2162  				s.curBlock.AddEdgeTo(s.lastDeferExit)
  2163  				s.endBlock()
  2164  				return s.lastDeferFinalBlock
  2165  			}
  2166  			s.openDeferExit()
  2167  		} else {
  2168  			s.rtcall(ir.Syms.Deferreturn, true, nil)
  2169  		}
  2170  	}
  2171  
  2172  	// Do actual return.
  2173  	// These currently turn into self-copies (in many cases).
  2174  	resultFields := s.curfn.Type().Results()
  2175  	results := make([]*ssa.Value, len(resultFields)+1, len(resultFields)+1)
  2176  	// Store SSAable and heap-escaped PPARAMOUT variables back to stack locations.
  2177  	for i, f := range resultFields {
  2178  		n := f.Nname.(*ir.Name)
  2179  		if s.canSSA(n) { // result is in some SSA variable
  2180  			if !n.IsOutputParamInRegisters() && n.Type().HasPointers() {
  2181  				// We are about to store to the result slot.
  2182  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
  2183  			}
  2184  			results[i] = s.variable(n, n.Type())
  2185  		} else if !n.OnStack() { // result is actually heap allocated
  2186  			// We are about to copy the in-heap result to the result slot.
  2187  			if n.Type().HasPointers() {
  2188  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
  2189  			}
  2190  			ha := s.expr(n.Heapaddr)
  2191  			s.instrumentFields(n.Type(), ha, instrumentRead)
  2192  			results[i] = s.newValue2(ssa.OpDereference, n.Type(), ha, s.mem())
  2193  		} else { // result is not SSA-able; not escaped, so not on heap, but too large for SSA.
  2194  			// Before register ABI this ought to be a self-move, home=dest,
  2195  			// With register ABI, it's still a self-move if parameter is on stack (i.e., too big or overflowed)
  2196  			// No VarDef, as the result slot is already holding live value.
  2197  			results[i] = s.newValue2(ssa.OpDereference, n.Type(), s.addr(n), s.mem())
  2198  		}
  2199  	}
  2200  
  2201  	// In -race mode, we need to call racefuncexit.
  2202  	// Note: This has to happen after we load any heap-allocated results,
  2203  	// otherwise races will be attributed to the caller instead.
  2204  	if s.instrumentEnterExit {
  2205  		s.rtcall(ir.Syms.Racefuncexit, true, nil)
  2206  	}
  2207  
  2208  	results[len(results)-1] = s.mem()
  2209  	m := s.newValue0(ssa.OpMakeResult, s.f.OwnAux.LateExpansionResultType())
  2210  	m.AddArgs(results...)
  2211  
  2212  	b := s.endBlock()
  2213  	b.Kind = ssa.BlockRet
  2214  	b.SetControl(m)
  2215  	if s.hasdefer && s.hasOpenDefers {
  2216  		s.lastDeferFinalBlock = b
  2217  	}
  2218  	return b
  2219  }
  2220  
  2221  type opAndType struct {
  2222  	op    ir.Op
  2223  	etype types.Kind
  2224  }
  2225  
  2226  var opToSSA = map[opAndType]ssa.Op{
  2227  	{ir.OADD, types.TINT8}:    ssa.OpAdd8,
  2228  	{ir.OADD, types.TUINT8}:   ssa.OpAdd8,
  2229  	{ir.OADD, types.TINT16}:   ssa.OpAdd16,
  2230  	{ir.OADD, types.TUINT16}:  ssa.OpAdd16,
  2231  	{ir.OADD, types.TINT32}:   ssa.OpAdd32,
  2232  	{ir.OADD, types.TUINT32}:  ssa.OpAdd32,
  2233  	{ir.OADD, types.TINT64}:   ssa.OpAdd64,
  2234  	{ir.OADD, types.TUINT64}:  ssa.OpAdd64,
  2235  	{ir.OADD, types.TFLOAT32}: ssa.OpAdd32F,
  2236  	{ir.OADD, types.TFLOAT64}: ssa.OpAdd64F,
  2237  
  2238  	{ir.OSUB, types.TINT8}:    ssa.OpSub8,
  2239  	{ir.OSUB, types.TUINT8}:   ssa.OpSub8,
  2240  	{ir.OSUB, types.TINT16}:   ssa.OpSub16,
  2241  	{ir.OSUB, types.TUINT16}:  ssa.OpSub16,
  2242  	{ir.OSUB, types.TINT32}:   ssa.OpSub32,
  2243  	{ir.OSUB, types.TUINT32}:  ssa.OpSub32,
  2244  	{ir.OSUB, types.TINT64}:   ssa.OpSub64,
  2245  	{ir.OSUB, types.TUINT64}:  ssa.OpSub64,
  2246  	{ir.OSUB, types.TFLOAT32}: ssa.OpSub32F,
  2247  	{ir.OSUB, types.TFLOAT64}: ssa.OpSub64F,
  2248  
  2249  	{ir.ONOT, types.TBOOL}: ssa.OpNot,
  2250  
  2251  	{ir.ONEG, types.TINT8}:    ssa.OpNeg8,
  2252  	{ir.ONEG, types.TUINT8}:   ssa.OpNeg8,
  2253  	{ir.ONEG, types.TINT16}:   ssa.OpNeg16,
  2254  	{ir.ONEG, types.TUINT16}:  ssa.OpNeg16,
  2255  	{ir.ONEG, types.TINT32}:   ssa.OpNeg32,
  2256  	{ir.ONEG, types.TUINT32}:  ssa.OpNeg32,
  2257  	{ir.ONEG, types.TINT64}:   ssa.OpNeg64,
  2258  	{ir.ONEG, types.TUINT64}:  ssa.OpNeg64,
  2259  	{ir.ONEG, types.TFLOAT32}: ssa.OpNeg32F,
  2260  	{ir.ONEG, types.TFLOAT64}: ssa.OpNeg64F,
  2261  
  2262  	{ir.OBITNOT, types.TINT8}:   ssa.OpCom8,
  2263  	{ir.OBITNOT, types.TUINT8}:  ssa.OpCom8,
  2264  	{ir.OBITNOT, types.TINT16}:  ssa.OpCom16,
  2265  	{ir.OBITNOT, types.TUINT16}: ssa.OpCom16,
  2266  	{ir.OBITNOT, types.TINT32}:  ssa.OpCom32,
  2267  	{ir.OBITNOT, types.TUINT32}: ssa.OpCom32,
  2268  	{ir.OBITNOT, types.TINT64}:  ssa.OpCom64,
  2269  	{ir.OBITNOT, types.TUINT64}: ssa.OpCom64,
  2270  
  2271  	{ir.OIMAG, types.TCOMPLEX64}:  ssa.OpComplexImag,
  2272  	{ir.OIMAG, types.TCOMPLEX128}: ssa.OpComplexImag,
  2273  	{ir.OREAL, types.TCOMPLEX64}:  ssa.OpComplexReal,
  2274  	{ir.OREAL, types.TCOMPLEX128}: ssa.OpComplexReal,
  2275  
  2276  	{ir.OMUL, types.TINT8}:    ssa.OpMul8,
  2277  	{ir.OMUL, types.TUINT8}:   ssa.OpMul8,
  2278  	{ir.OMUL, types.TINT16}:   ssa.OpMul16,
  2279  	{ir.OMUL, types.TUINT16}:  ssa.OpMul16,
  2280  	{ir.OMUL, types.TINT32}:   ssa.OpMul32,
  2281  	{ir.OMUL, types.TUINT32}:  ssa.OpMul32,
  2282  	{ir.OMUL, types.TINT64}:   ssa.OpMul64,
  2283  	{ir.OMUL, types.TUINT64}:  ssa.OpMul64,
  2284  	{ir.OMUL, types.TFLOAT32}: ssa.OpMul32F,
  2285  	{ir.OMUL, types.TFLOAT64}: ssa.OpMul64F,
  2286  
  2287  	{ir.ODIV, types.TFLOAT32}: ssa.OpDiv32F,
  2288  	{ir.ODIV, types.TFLOAT64}: ssa.OpDiv64F,
  2289  
  2290  	{ir.ODIV, types.TINT8}:   ssa.OpDiv8,
  2291  	{ir.ODIV, types.TUINT8}:  ssa.OpDiv8u,
  2292  	{ir.ODIV, types.TINT16}:  ssa.OpDiv16,
  2293  	{ir.ODIV, types.TUINT16}: ssa.OpDiv16u,
  2294  	{ir.ODIV, types.TINT32}:  ssa.OpDiv32,
  2295  	{ir.ODIV, types.TUINT32}: ssa.OpDiv32u,
  2296  	{ir.ODIV, types.TINT64}:  ssa.OpDiv64,
  2297  	{ir.ODIV, types.TUINT64}: ssa.OpDiv64u,
  2298  
  2299  	{ir.OMOD, types.TINT8}:   ssa.OpMod8,
  2300  	{ir.OMOD, types.TUINT8}:  ssa.OpMod8u,
  2301  	{ir.OMOD, types.TINT16}:  ssa.OpMod16,
  2302  	{ir.OMOD, types.TUINT16}: ssa.OpMod16u,
  2303  	{ir.OMOD, types.TINT32}:  ssa.OpMod32,
  2304  	{ir.OMOD, types.TUINT32}: ssa.OpMod32u,
  2305  	{ir.OMOD, types.TINT64}:  ssa.OpMod64,
  2306  	{ir.OMOD, types.TUINT64}: ssa.OpMod64u,
  2307  
  2308  	{ir.OAND, types.TINT8}:   ssa.OpAnd8,
  2309  	{ir.OAND, types.TUINT8}:  ssa.OpAnd8,
  2310  	{ir.OAND, types.TINT16}:  ssa.OpAnd16,
  2311  	{ir.OAND, types.TUINT16}: ssa.OpAnd16,
  2312  	{ir.OAND, types.TINT32}:  ssa.OpAnd32,
  2313  	{ir.OAND, types.TUINT32}: ssa.OpAnd32,
  2314  	{ir.OAND, types.TINT64}:  ssa.OpAnd64,
  2315  	{ir.OAND, types.TUINT64}: ssa.OpAnd64,
  2316  
  2317  	{ir.OOR, types.TINT8}:   ssa.OpOr8,
  2318  	{ir.OOR, types.TUINT8}:  ssa.OpOr8,
  2319  	{ir.OOR, types.TINT16}:  ssa.OpOr16,
  2320  	{ir.OOR, types.TUINT16}: ssa.OpOr16,
  2321  	{ir.OOR, types.TINT32}:  ssa.OpOr32,
  2322  	{ir.OOR, types.TUINT32}: ssa.OpOr32,
  2323  	{ir.OOR, types.TINT64}:  ssa.OpOr64,
  2324  	{ir.OOR, types.TUINT64}: ssa.OpOr64,
  2325  
  2326  	{ir.OXOR, types.TINT8}:   ssa.OpXor8,
  2327  	{ir.OXOR, types.TUINT8}:  ssa.OpXor8,
  2328  	{ir.OXOR, types.TINT16}:  ssa.OpXor16,
  2329  	{ir.OXOR, types.TUINT16}: ssa.OpXor16,
  2330  	{ir.OXOR, types.TINT32}:  ssa.OpXor32,
  2331  	{ir.OXOR, types.TUINT32}: ssa.OpXor32,
  2332  	{ir.OXOR, types.TINT64}:  ssa.OpXor64,
  2333  	{ir.OXOR, types.TUINT64}: ssa.OpXor64,
  2334  
  2335  	{ir.OEQ, types.TBOOL}:      ssa.OpEqB,
  2336  	{ir.OEQ, types.TINT8}:      ssa.OpEq8,
  2337  	{ir.OEQ, types.TUINT8}:     ssa.OpEq8,
  2338  	{ir.OEQ, types.TINT16}:     ssa.OpEq16,
  2339  	{ir.OEQ, types.TUINT16}:    ssa.OpEq16,
  2340  	{ir.OEQ, types.TINT32}:     ssa.OpEq32,
  2341  	{ir.OEQ, types.TUINT32}:    ssa.OpEq32,
  2342  	{ir.OEQ, types.TINT64}:     ssa.OpEq64,
  2343  	{ir.OEQ, types.TUINT64}:    ssa.OpEq64,
  2344  	{ir.OEQ, types.TINTER}:     ssa.OpEqInter,
  2345  	{ir.OEQ, types.TSLICE}:     ssa.OpEqSlice,
  2346  	{ir.OEQ, types.TFUNC}:      ssa.OpEqPtr,
  2347  	{ir.OEQ, types.TMAP}:       ssa.OpEqPtr,
  2348  	{ir.OEQ, types.TCHAN}:      ssa.OpEqPtr,
  2349  	{ir.OEQ, types.TPTR}:       ssa.OpEqPtr,
  2350  	{ir.OEQ, types.TUINTPTR}:   ssa.OpEqPtr,
  2351  	{ir.OEQ, types.TUNSAFEPTR}: ssa.OpEqPtr,
  2352  	{ir.OEQ, types.TFLOAT64}:   ssa.OpEq64F,
  2353  	{ir.OEQ, types.TFLOAT32}:   ssa.OpEq32F,
  2354  
  2355  	{ir.ONE, types.TBOOL}:      ssa.OpNeqB,
  2356  	{ir.ONE, types.TINT8}:      ssa.OpNeq8,
  2357  	{ir.ONE, types.TUINT8}:     ssa.OpNeq8,
  2358  	{ir.ONE, types.TINT16}:     ssa.OpNeq16,
  2359  	{ir.ONE, types.TUINT16}:    ssa.OpNeq16,
  2360  	{ir.ONE, types.TINT32}:     ssa.OpNeq32,
  2361  	{ir.ONE, types.TUINT32}:    ssa.OpNeq32,
  2362  	{ir.ONE, types.TINT64}:     ssa.OpNeq64,
  2363  	{ir.ONE, types.TUINT64}:    ssa.OpNeq64,
  2364  	{ir.ONE, types.TINTER}:     ssa.OpNeqInter,
  2365  	{ir.ONE, types.TSLICE}:     ssa.OpNeqSlice,
  2366  	{ir.ONE, types.TFUNC}:      ssa.OpNeqPtr,
  2367  	{ir.ONE, types.TMAP}:       ssa.OpNeqPtr,
  2368  	{ir.ONE, types.TCHAN}:      ssa.OpNeqPtr,
  2369  	{ir.ONE, types.TPTR}:       ssa.OpNeqPtr,
  2370  	{ir.ONE, types.TUINTPTR}:   ssa.OpNeqPtr,
  2371  	{ir.ONE, types.TUNSAFEPTR}: ssa.OpNeqPtr,
  2372  	{ir.ONE, types.TFLOAT64}:   ssa.OpNeq64F,
  2373  	{ir.ONE, types.TFLOAT32}:   ssa.OpNeq32F,
  2374  
  2375  	{ir.OLT, types.TINT8}:    ssa.OpLess8,
  2376  	{ir.OLT, types.TUINT8}:   ssa.OpLess8U,
  2377  	{ir.OLT, types.TINT16}:   ssa.OpLess16,
  2378  	{ir.OLT, types.TUINT16}:  ssa.OpLess16U,
  2379  	{ir.OLT, types.TINT32}:   ssa.OpLess32,
  2380  	{ir.OLT, types.TUINT32}:  ssa.OpLess32U,
  2381  	{ir.OLT, types.TINT64}:   ssa.OpLess64,
  2382  	{ir.OLT, types.TUINT64}:  ssa.OpLess64U,
  2383  	{ir.OLT, types.TFLOAT64}: ssa.OpLess64F,
  2384  	{ir.OLT, types.TFLOAT32}: ssa.OpLess32F,
  2385  
  2386  	{ir.OLE, types.TINT8}:    ssa.OpLeq8,
  2387  	{ir.OLE, types.TUINT8}:   ssa.OpLeq8U,
  2388  	{ir.OLE, types.TINT16}:   ssa.OpLeq16,
  2389  	{ir.OLE, types.TUINT16}:  ssa.OpLeq16U,
  2390  	{ir.OLE, types.TINT32}:   ssa.OpLeq32,
  2391  	{ir.OLE, types.TUINT32}:  ssa.OpLeq32U,
  2392  	{ir.OLE, types.TINT64}:   ssa.OpLeq64,
  2393  	{ir.OLE, types.TUINT64}:  ssa.OpLeq64U,
  2394  	{ir.OLE, types.TFLOAT64}: ssa.OpLeq64F,
  2395  	{ir.OLE, types.TFLOAT32}: ssa.OpLeq32F,
  2396  }
  2397  
  2398  func (s *state) concreteEtype(t *types.Type) types.Kind {
  2399  	e := t.Kind()
  2400  	switch e {
  2401  	default:
  2402  		return e
  2403  	case types.TINT:
  2404  		if s.config.PtrSize == 8 {
  2405  			return types.TINT64
  2406  		}
  2407  		return types.TINT32
  2408  	case types.TUINT:
  2409  		if s.config.PtrSize == 8 {
  2410  			return types.TUINT64
  2411  		}
  2412  		return types.TUINT32
  2413  	case types.TUINTPTR:
  2414  		if s.config.PtrSize == 8 {
  2415  			return types.TUINT64
  2416  		}
  2417  		return types.TUINT32
  2418  	}
  2419  }
  2420  
  2421  func (s *state) ssaOp(op ir.Op, t *types.Type) ssa.Op {
  2422  	etype := s.concreteEtype(t)
  2423  	x, ok := opToSSA[opAndType{op, etype}]
  2424  	if !ok {
  2425  		s.Fatalf("unhandled binary op %v %s", op, etype)
  2426  	}
  2427  	return x
  2428  }
  2429  
  2430  type opAndTwoTypes struct {
  2431  	op     ir.Op
  2432  	etype1 types.Kind
  2433  	etype2 types.Kind
  2434  }
  2435  
  2436  type twoTypes struct {
  2437  	etype1 types.Kind
  2438  	etype2 types.Kind
  2439  }
  2440  
  2441  type twoOpsAndType struct {
  2442  	op1              ssa.Op
  2443  	op2              ssa.Op
  2444  	intermediateType types.Kind
  2445  }
  2446  
  2447  var fpConvOpToSSA = map[twoTypes]twoOpsAndType{
  2448  
  2449  	{types.TINT8, types.TFLOAT32}:  {ssa.OpSignExt8to32, ssa.OpCvt32to32F, types.TINT32},
  2450  	{types.TINT16, types.TFLOAT32}: {ssa.OpSignExt16to32, ssa.OpCvt32to32F, types.TINT32},
  2451  	{types.TINT32, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt32to32F, types.TINT32},
  2452  	{types.TINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt64to32F, types.TINT64},
  2453  
  2454  	{types.TINT8, types.TFLOAT64}:  {ssa.OpSignExt8to32, ssa.OpCvt32to64F, types.TINT32},
  2455  	{types.TINT16, types.TFLOAT64}: {ssa.OpSignExt16to32, ssa.OpCvt32to64F, types.TINT32},
  2456  	{types.TINT32, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt32to64F, types.TINT32},
  2457  	{types.TINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt64to64F, types.TINT64},
  2458  
  2459  	{types.TFLOAT32, types.TINT8}:  {ssa.OpCvt32Fto32, ssa.OpTrunc32to8, types.TINT32},
  2460  	{types.TFLOAT32, types.TINT16}: {ssa.OpCvt32Fto32, ssa.OpTrunc32to16, types.TINT32},
  2461  	{types.TFLOAT32, types.TINT32}: {ssa.OpCvt32Fto32, ssa.OpCopy, types.TINT32},
  2462  	{types.TFLOAT32, types.TINT64}: {ssa.OpCvt32Fto64, ssa.OpCopy, types.TINT64},
  2463  
  2464  	{types.TFLOAT64, types.TINT8}:  {ssa.OpCvt64Fto32, ssa.OpTrunc32to8, types.TINT32},
  2465  	{types.TFLOAT64, types.TINT16}: {ssa.OpCvt64Fto32, ssa.OpTrunc32to16, types.TINT32},
  2466  	{types.TFLOAT64, types.TINT32}: {ssa.OpCvt64Fto32, ssa.OpCopy, types.TINT32},
  2467  	{types.TFLOAT64, types.TINT64}: {ssa.OpCvt64Fto64, ssa.OpCopy, types.TINT64},
  2468  	// unsigned
  2469  	{types.TUINT8, types.TFLOAT32}:  {ssa.OpZeroExt8to32, ssa.OpCvt32to32F, types.TINT32},
  2470  	{types.TUINT16, types.TFLOAT32}: {ssa.OpZeroExt16to32, ssa.OpCvt32to32F, types.TINT32},
  2471  	{types.TUINT32, types.TFLOAT32}: {ssa.OpZeroExt32to64, ssa.OpCvt64to32F, types.TINT64}, // go wide to dodge unsigned
  2472  	{types.TUINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpInvalid, types.TUINT64},            // Cvt64Uto32F, branchy code expansion instead
  2473  
  2474  	{types.TUINT8, types.TFLOAT64}:  {ssa.OpZeroExt8to32, ssa.OpCvt32to64F, types.TINT32},
  2475  	{types.TUINT16, types.TFLOAT64}: {ssa.OpZeroExt16to32, ssa.OpCvt32to64F, types.TINT32},
  2476  	{types.TUINT32, types.TFLOAT64}: {ssa.OpZeroExt32to64, ssa.OpCvt64to64F, types.TINT64}, // go wide to dodge unsigned
  2477  	{types.TUINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpInvalid, types.TUINT64},            // Cvt64Uto64F, branchy code expansion instead
  2478  
  2479  	{types.TFLOAT32, types.TUINT8}:  {ssa.OpCvt32Fto32, ssa.OpTrunc32to8, types.TINT32},
  2480  	{types.TFLOAT32, types.TUINT16}: {ssa.OpCvt32Fto32, ssa.OpTrunc32to16, types.TINT32},
  2481  	{types.TFLOAT32, types.TUINT32}: {ssa.OpCvt32Fto64, ssa.OpTrunc64to32, types.TINT64}, // go wide to dodge unsigned
  2482  	{types.TFLOAT32, types.TUINT64}: {ssa.OpInvalid, ssa.OpCopy, types.TUINT64},          // Cvt32Fto64U, branchy code expansion instead
  2483  
  2484  	{types.TFLOAT64, types.TUINT8}:  {ssa.OpCvt64Fto32, ssa.OpTrunc32to8, types.TINT32},
  2485  	{types.TFLOAT64, types.TUINT16}: {ssa.OpCvt64Fto32, ssa.OpTrunc32to16, types.TINT32},
  2486  	{types.TFLOAT64, types.TUINT32}: {ssa.OpCvt64Fto64, ssa.OpTrunc64to32, types.TINT64}, // go wide to dodge unsigned
  2487  	{types.TFLOAT64, types.TUINT64}: {ssa.OpInvalid, ssa.OpCopy, types.TUINT64},          // Cvt64Fto64U, branchy code expansion instead
  2488  
  2489  	// float
  2490  	{types.TFLOAT64, types.TFLOAT32}: {ssa.OpCvt64Fto32F, ssa.OpCopy, types.TFLOAT32},
  2491  	{types.TFLOAT64, types.TFLOAT64}: {ssa.OpRound64F, ssa.OpCopy, types.TFLOAT64},
  2492  	{types.TFLOAT32, types.TFLOAT32}: {ssa.OpRound32F, ssa.OpCopy, types.TFLOAT32},
  2493  	{types.TFLOAT32, types.TFLOAT64}: {ssa.OpCvt32Fto64F, ssa.OpCopy, types.TFLOAT64},
  2494  }
  2495  
  2496  // this map is used only for 32-bit arch, and only includes the difference
  2497  // on 32-bit arch, don't use int64<->float conversion for uint32
  2498  var fpConvOpToSSA32 = map[twoTypes]twoOpsAndType{
  2499  	{types.TUINT32, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt32Uto32F, types.TUINT32},
  2500  	{types.TUINT32, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt32Uto64F, types.TUINT32},
  2501  	{types.TFLOAT32, types.TUINT32}: {ssa.OpCvt32Fto32U, ssa.OpCopy, types.TUINT32},
  2502  	{types.TFLOAT64, types.TUINT32}: {ssa.OpCvt64Fto32U, ssa.OpCopy, types.TUINT32},
  2503  }
  2504  
  2505  // uint64<->float conversions, only on machines that have instructions for that
  2506  var uint64fpConvOpToSSA = map[twoTypes]twoOpsAndType{
  2507  	{types.TUINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt64Uto32F, types.TUINT64},
  2508  	{types.TUINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt64Uto64F, types.TUINT64},
  2509  	{types.TFLOAT32, types.TUINT64}: {ssa.OpCvt32Fto64U, ssa.OpCopy, types.TUINT64},
  2510  	{types.TFLOAT64, types.TUINT64}: {ssa.OpCvt64Fto64U, ssa.OpCopy, types.TUINT64},
  2511  }
  2512  
  2513  var shiftOpToSSA = map[opAndTwoTypes]ssa.Op{
  2514  	{ir.OLSH, types.TINT8, types.TUINT8}:   ssa.OpLsh8x8,
  2515  	{ir.OLSH, types.TUINT8, types.TUINT8}:  ssa.OpLsh8x8,
  2516  	{ir.OLSH, types.TINT8, types.TUINT16}:  ssa.OpLsh8x16,
  2517  	{ir.OLSH, types.TUINT8, types.TUINT16}: ssa.OpLsh8x16,
  2518  	{ir.OLSH, types.TINT8, types.TUINT32}:  ssa.OpLsh8x32,
  2519  	{ir.OLSH, types.TUINT8, types.TUINT32}: ssa.OpLsh8x32,
  2520  	{ir.OLSH, types.TINT8, types.TUINT64}:  ssa.OpLsh8x64,
  2521  	{ir.OLSH, types.TUINT8, types.TUINT64}: ssa.OpLsh8x64,
  2522  
  2523  	{ir.OLSH, types.TINT16, types.TUINT8}:   ssa.OpLsh16x8,
  2524  	{ir.OLSH, types.TUINT16, types.TUINT8}:  ssa.OpLsh16x8,
  2525  	{ir.OLSH, types.TINT16, types.TUINT16}:  ssa.OpLsh16x16,
  2526  	{ir.OLSH, types.TUINT16, types.TUINT16}: ssa.OpLsh16x16,
  2527  	{ir.OLSH, types.TINT16, types.TUINT32}:  ssa.OpLsh16x32,
  2528  	{ir.OLSH, types.TUINT16, types.TUINT32}: ssa.OpLsh16x32,
  2529  	{ir.OLSH, types.TINT16, types.TUINT64}:  ssa.OpLsh16x64,
  2530  	{ir.OLSH, types.TUINT16, types.TUINT64}: ssa.OpLsh16x64,
  2531  
  2532  	{ir.OLSH, types.TINT32, types.TUINT8}:   ssa.OpLsh32x8,
  2533  	{ir.OLSH, types.TUINT32, types.TUINT8}:  ssa.OpLsh32x8,
  2534  	{ir.OLSH, types.TINT32, types.TUINT16}:  ssa.OpLsh32x16,
  2535  	{ir.OLSH, types.TUINT32, types.TUINT16}: ssa.OpLsh32x16,
  2536  	{ir.OLSH, types.TINT32, types.TUINT32}:  ssa.OpLsh32x32,
  2537  	{ir.OLSH, types.TUINT32, types.TUINT32}: ssa.OpLsh32x32,
  2538  	{ir.OLSH, types.TINT32, types.TUINT64}:  ssa.OpLsh32x64,
  2539  	{ir.OLSH, types.TUINT32, types.TUINT64}: ssa.OpLsh32x64,
  2540  
  2541  	{ir.OLSH, types.TINT64, types.TUINT8}:   ssa.OpLsh64x8,
  2542  	{ir.OLSH, types.TUINT64, types.TUINT8}:  ssa.OpLsh64x8,
  2543  	{ir.OLSH, types.TINT64, types.TUINT16}:  ssa.OpLsh64x16,
  2544  	{ir.OLSH, types.TUINT64, types.TUINT16}: ssa.OpLsh64x16,
  2545  	{ir.OLSH, types.TINT64, types.TUINT32}:  ssa.OpLsh64x32,
  2546  	{ir.OLSH, types.TUINT64, types.TUINT32}: ssa.OpLsh64x32,
  2547  	{ir.OLSH, types.TINT64, types.TUINT64}:  ssa.OpLsh64x64,
  2548  	{ir.OLSH, types.TUINT64, types.TUINT64}: ssa.OpLsh64x64,
  2549  
  2550  	{ir.ORSH, types.TINT8, types.TUINT8}:   ssa.OpRsh8x8,
  2551  	{ir.ORSH, types.TUINT8, types.TUINT8}:  ssa.OpRsh8Ux8,
  2552  	{ir.ORSH, types.TINT8, types.TUINT16}:  ssa.OpRsh8x16,
  2553  	{ir.ORSH, types.TUINT8, types.TUINT16}: ssa.OpRsh8Ux16,
  2554  	{ir.ORSH, types.TINT8, types.TUINT32}:  ssa.OpRsh8x32,
  2555  	{ir.ORSH, types.TUINT8, types.TUINT32}: ssa.OpRsh8Ux32,
  2556  	{ir.ORSH, types.TINT8, types.TUINT64}:  ssa.OpRsh8x64,
  2557  	{ir.ORSH, types.TUINT8, types.TUINT64}: ssa.OpRsh8Ux64,
  2558  
  2559  	{ir.ORSH, types.TINT16, types.TUINT8}:   ssa.OpRsh16x8,
  2560  	{ir.ORSH, types.TUINT16, types.TUINT8}:  ssa.OpRsh16Ux8,
  2561  	{ir.ORSH, types.TINT16, types.TUINT16}:  ssa.OpRsh16x16,
  2562  	{ir.ORSH, types.TUINT16, types.TUINT16}: ssa.OpRsh16Ux16,
  2563  	{ir.ORSH, types.TINT16, types.TUINT32}:  ssa.OpRsh16x32,
  2564  	{ir.ORSH, types.TUINT16, types.TUINT32}: ssa.OpRsh16Ux32,
  2565  	{ir.ORSH, types.TINT16, types.TUINT64}:  ssa.OpRsh16x64,
  2566  	{ir.ORSH, types.TUINT16, types.TUINT64}: ssa.OpRsh16Ux64,
  2567  
  2568  	{ir.ORSH, types.TINT32, types.TUINT8}:   ssa.OpRsh32x8,
  2569  	{ir.ORSH, types.TUINT32, types.TUINT8}:  ssa.OpRsh32Ux8,
  2570  	{ir.ORSH, types.TINT32, types.TUINT16}:  ssa.OpRsh32x16,
  2571  	{ir.ORSH, types.TUINT32, types.TUINT16}: ssa.OpRsh32Ux16,
  2572  	{ir.ORSH, types.TINT32, types.TUINT32}:  ssa.OpRsh32x32,
  2573  	{ir.ORSH, types.TUINT32, types.TUINT32}: ssa.OpRsh32Ux32,
  2574  	{ir.ORSH, types.TINT32, types.TUINT64}:  ssa.OpRsh32x64,
  2575  	{ir.ORSH, types.TUINT32, types.TUINT64}: ssa.OpRsh32Ux64,
  2576  
  2577  	{ir.ORSH, types.TINT64, types.TUINT8}:   ssa.OpRsh64x8,
  2578  	{ir.ORSH, types.TUINT64, types.TUINT8}:  ssa.OpRsh64Ux8,
  2579  	{ir.ORSH, types.TINT64, types.TUINT16}:  ssa.OpRsh64x16,
  2580  	{ir.ORSH, types.TUINT64, types.TUINT16}: ssa.OpRsh64Ux16,
  2581  	{ir.ORSH, types.TINT64, types.TUINT32}:  ssa.OpRsh64x32,
  2582  	{ir.ORSH, types.TUINT64, types.TUINT32}: ssa.OpRsh64Ux32,
  2583  	{ir.ORSH, types.TINT64, types.TUINT64}:  ssa.OpRsh64x64,
  2584  	{ir.ORSH, types.TUINT64, types.TUINT64}: ssa.OpRsh64Ux64,
  2585  }
  2586  
  2587  func (s *state) ssaShiftOp(op ir.Op, t *types.Type, u *types.Type) ssa.Op {
  2588  	etype1 := s.concreteEtype(t)
  2589  	etype2 := s.concreteEtype(u)
  2590  	x, ok := shiftOpToSSA[opAndTwoTypes{op, etype1, etype2}]
  2591  	if !ok {
  2592  		s.Fatalf("unhandled shift op %v etype=%s/%s", op, etype1, etype2)
  2593  	}
  2594  	return x
  2595  }
  2596  
  2597  func (s *state) uintptrConstant(v uint64) *ssa.Value {
  2598  	if s.config.PtrSize == 4 {
  2599  		return s.newValue0I(ssa.OpConst32, types.Types[types.TUINTPTR], int64(v))
  2600  	}
  2601  	return s.newValue0I(ssa.OpConst64, types.Types[types.TUINTPTR], int64(v))
  2602  }
  2603  
  2604  func (s *state) conv(n ir.Node, v *ssa.Value, ft, tt *types.Type) *ssa.Value {
  2605  	if ft.IsBoolean() && tt.IsKind(types.TUINT8) {
  2606  		// Bool -> uint8 is generated internally when indexing into runtime.staticbyte.
  2607  		return s.newValue1(ssa.OpCvtBoolToUint8, tt, v)
  2608  	}
  2609  	if ft.IsInteger() && tt.IsInteger() {
  2610  		var op ssa.Op
  2611  		if tt.Size() == ft.Size() {
  2612  			op = ssa.OpCopy
  2613  		} else if tt.Size() < ft.Size() {
  2614  			// truncation
  2615  			switch 10*ft.Size() + tt.Size() {
  2616  			case 21:
  2617  				op = ssa.OpTrunc16to8
  2618  			case 41:
  2619  				op = ssa.OpTrunc32to8
  2620  			case 42:
  2621  				op = ssa.OpTrunc32to16
  2622  			case 81:
  2623  				op = ssa.OpTrunc64to8
  2624  			case 82:
  2625  				op = ssa.OpTrunc64to16
  2626  			case 84:
  2627  				op = ssa.OpTrunc64to32
  2628  			default:
  2629  				s.Fatalf("weird integer truncation %v -> %v", ft, tt)
  2630  			}
  2631  		} else if ft.IsSigned() {
  2632  			// sign extension
  2633  			switch 10*ft.Size() + tt.Size() {
  2634  			case 12:
  2635  				op = ssa.OpSignExt8to16
  2636  			case 14:
  2637  				op = ssa.OpSignExt8to32
  2638  			case 18:
  2639  				op = ssa.OpSignExt8to64
  2640  			case 24:
  2641  				op = ssa.OpSignExt16to32
  2642  			case 28:
  2643  				op = ssa.OpSignExt16to64
  2644  			case 48:
  2645  				op = ssa.OpSignExt32to64
  2646  			default:
  2647  				s.Fatalf("bad integer sign extension %v -> %v", ft, tt)
  2648  			}
  2649  		} else {
  2650  			// zero extension
  2651  			switch 10*ft.Size() + tt.Size() {
  2652  			case 12:
  2653  				op = ssa.OpZeroExt8to16
  2654  			case 14:
  2655  				op = ssa.OpZeroExt8to32
  2656  			case 18:
  2657  				op = ssa.OpZeroExt8to64
  2658  			case 24:
  2659  				op = ssa.OpZeroExt16to32
  2660  			case 28:
  2661  				op = ssa.OpZeroExt16to64
  2662  			case 48:
  2663  				op = ssa.OpZeroExt32to64
  2664  			default:
  2665  				s.Fatalf("weird integer sign extension %v -> %v", ft, tt)
  2666  			}
  2667  		}
  2668  		return s.newValue1(op, tt, v)
  2669  	}
  2670  
  2671  	if ft.IsComplex() && tt.IsComplex() {
  2672  		var op ssa.Op
  2673  		if ft.Size() == tt.Size() {
  2674  			switch ft.Size() {
  2675  			case 8:
  2676  				op = ssa.OpRound32F
  2677  			case 16:
  2678  				op = ssa.OpRound64F
  2679  			default:
  2680  				s.Fatalf("weird complex conversion %v -> %v", ft, tt)
  2681  			}
  2682  		} else if ft.Size() == 8 && tt.Size() == 16 {
  2683  			op = ssa.OpCvt32Fto64F
  2684  		} else if ft.Size() == 16 && tt.Size() == 8 {
  2685  			op = ssa.OpCvt64Fto32F
  2686  		} else {
  2687  			s.Fatalf("weird complex conversion %v -> %v", ft, tt)
  2688  		}
  2689  		ftp := types.FloatForComplex(ft)
  2690  		ttp := types.FloatForComplex(tt)
  2691  		return s.newValue2(ssa.OpComplexMake, tt,
  2692  			s.newValueOrSfCall1(op, ttp, s.newValue1(ssa.OpComplexReal, ftp, v)),
  2693  			s.newValueOrSfCall1(op, ttp, s.newValue1(ssa.OpComplexImag, ftp, v)))
  2694  	}
  2695  
  2696  	if tt.IsComplex() { // and ft is not complex
  2697  		// Needed for generics support - can't happen in normal Go code.
  2698  		et := types.FloatForComplex(tt)
  2699  		v = s.conv(n, v, ft, et)
  2700  		return s.newValue2(ssa.OpComplexMake, tt, v, s.zeroVal(et))
  2701  	}
  2702  
  2703  	if ft.IsFloat() || tt.IsFloat() {
  2704  		conv, ok := fpConvOpToSSA[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]
  2705  		if s.config.RegSize == 4 && Arch.LinkArch.Family != sys.MIPS && !s.softFloat {
  2706  			if conv1, ok1 := fpConvOpToSSA32[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
  2707  				conv = conv1
  2708  			}
  2709  		}
  2710  		if Arch.LinkArch.Family == sys.ARM64 || Arch.LinkArch.Family == sys.Wasm || Arch.LinkArch.Family == sys.S390X || s.softFloat {
  2711  			if conv1, ok1 := uint64fpConvOpToSSA[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
  2712  				conv = conv1
  2713  			}
  2714  		}
  2715  
  2716  		if Arch.LinkArch.Family == sys.MIPS && !s.softFloat {
  2717  			if ft.Size() == 4 && ft.IsInteger() && !ft.IsSigned() {
  2718  				// tt is float32 or float64, and ft is also unsigned
  2719  				if tt.Size() == 4 {
  2720  					return s.uint32Tofloat32(n, v, ft, tt)
  2721  				}
  2722  				if tt.Size() == 8 {
  2723  					return s.uint32Tofloat64(n, v, ft, tt)
  2724  				}
  2725  			} else if tt.Size() == 4 && tt.IsInteger() && !tt.IsSigned() {
  2726  				// ft is float32 or float64, and tt is unsigned integer
  2727  				if ft.Size() == 4 {
  2728  					return s.float32ToUint32(n, v, ft, tt)
  2729  				}
  2730  				if ft.Size() == 8 {
  2731  					return s.float64ToUint32(n, v, ft, tt)
  2732  				}
  2733  			}
  2734  		}
  2735  
  2736  		if !ok {
  2737  			s.Fatalf("weird float conversion %v -> %v", ft, tt)
  2738  		}
  2739  		op1, op2, it := conv.op1, conv.op2, conv.intermediateType
  2740  
  2741  		if op1 != ssa.OpInvalid && op2 != ssa.OpInvalid {
  2742  			// normal case, not tripping over unsigned 64
  2743  			if op1 == ssa.OpCopy {
  2744  				if op2 == ssa.OpCopy {
  2745  					return v
  2746  				}
  2747  				return s.newValueOrSfCall1(op2, tt, v)
  2748  			}
  2749  			if op2 == ssa.OpCopy {
  2750  				return s.newValueOrSfCall1(op1, tt, v)
  2751  			}
  2752  			return s.newValueOrSfCall1(op2, tt, s.newValueOrSfCall1(op1, types.Types[it], v))
  2753  		}
  2754  		// Tricky 64-bit unsigned cases.
  2755  		if ft.IsInteger() {
  2756  			// tt is float32 or float64, and ft is also unsigned
  2757  			if tt.Size() == 4 {
  2758  				return s.uint64Tofloat32(n, v, ft, tt)
  2759  			}
  2760  			if tt.Size() == 8 {
  2761  				return s.uint64Tofloat64(n, v, ft, tt)
  2762  			}
  2763  			s.Fatalf("weird unsigned integer to float conversion %v -> %v", ft, tt)
  2764  		}
  2765  		// ft is float32 or float64, and tt is unsigned integer
  2766  		if ft.Size() == 4 {
  2767  			return s.float32ToUint64(n, v, ft, tt)
  2768  		}
  2769  		if ft.Size() == 8 {
  2770  			return s.float64ToUint64(n, v, ft, tt)
  2771  		}
  2772  		s.Fatalf("weird float to unsigned integer conversion %v -> %v", ft, tt)
  2773  		return nil
  2774  	}
  2775  
  2776  	s.Fatalf("unhandled OCONV %s -> %s", ft.Kind(), tt.Kind())
  2777  	return nil
  2778  }
  2779  
  2780  // expr converts the expression n to ssa, adds it to s and returns the ssa result.
  2781  func (s *state) expr(n ir.Node) *ssa.Value {
  2782  	return s.exprCheckPtr(n, true)
  2783  }
  2784  
  2785  func (s *state) exprCheckPtr(n ir.Node, checkPtrOK bool) *ssa.Value {
  2786  	if ir.HasUniquePos(n) {
  2787  		// ONAMEs and named OLITERALs have the line number
  2788  		// of the decl, not the use. See issue 14742.
  2789  		s.pushLine(n.Pos())
  2790  		defer s.popLine()
  2791  	}
  2792  
  2793  	s.stmtList(n.Init())
  2794  	switch n.Op() {
  2795  	case ir.OBYTES2STRTMP:
  2796  		n := n.(*ir.ConvExpr)
  2797  		slice := s.expr(n.X)
  2798  		ptr := s.newValue1(ssa.OpSlicePtr, s.f.Config.Types.BytePtr, slice)
  2799  		len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], slice)
  2800  		return s.newValue2(ssa.OpStringMake, n.Type(), ptr, len)
  2801  	case ir.OSTR2BYTESTMP:
  2802  		n := n.(*ir.ConvExpr)
  2803  		str := s.expr(n.X)
  2804  		ptr := s.newValue1(ssa.OpStringPtr, s.f.Config.Types.BytePtr, str)
  2805  		if !n.NonNil() {
  2806  			// We need to ensure []byte("") evaluates to []byte{}, and not []byte(nil).
  2807  			//
  2808  			// TODO(mdempsky): Investigate using "len != 0" instead of "ptr != nil".
  2809  			cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], ptr, s.constNil(ptr.Type))
  2810  			zerobase := s.newValue1A(ssa.OpAddr, ptr.Type, ir.Syms.Zerobase, s.sb)
  2811  			ptr = s.ternary(cond, ptr, zerobase)
  2812  		}
  2813  		len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], str)
  2814  		return s.newValue3(ssa.OpSliceMake, n.Type(), ptr, len, len)
  2815  	case ir.OCFUNC:
  2816  		n := n.(*ir.UnaryExpr)
  2817  		aux := n.X.(*ir.Name).Linksym()
  2818  		// OCFUNC is used to build function values, which must
  2819  		// always reference ABIInternal entry points.
  2820  		if aux.ABI() != obj.ABIInternal {
  2821  			s.Fatalf("expected ABIInternal: %v", aux.ABI())
  2822  		}
  2823  		return s.entryNewValue1A(ssa.OpAddr, n.Type(), aux, s.sb)
  2824  	case ir.ONAME:
  2825  		n := n.(*ir.Name)
  2826  		if n.Class == ir.PFUNC {
  2827  			// "value" of a function is the address of the function's closure
  2828  			sym := staticdata.FuncLinksym(n)
  2829  			return s.entryNewValue1A(ssa.OpAddr, types.NewPtr(n.Type()), sym, s.sb)
  2830  		}
  2831  		if s.canSSA(n) {
  2832  			return s.variable(n, n.Type())
  2833  		}
  2834  		return s.load(n.Type(), s.addr(n))
  2835  	case ir.OLINKSYMOFFSET:
  2836  		n := n.(*ir.LinksymOffsetExpr)
  2837  		return s.load(n.Type(), s.addr(n))
  2838  	case ir.ONIL:
  2839  		n := n.(*ir.NilExpr)
  2840  		t := n.Type()
  2841  		switch {
  2842  		case t.IsSlice():
  2843  			return s.constSlice(t)
  2844  		case t.IsInterface():
  2845  			return s.constInterface(t)
  2846  		default:
  2847  			return s.constNil(t)
  2848  		}
  2849  	case ir.OLITERAL:
  2850  		switch u := n.Val(); u.Kind() {
  2851  		case constant.Int:
  2852  			i := ir.IntVal(n.Type(), u)
  2853  			switch n.Type().Size() {
  2854  			case 1:
  2855  				return s.constInt8(n.Type(), int8(i))
  2856  			case 2:
  2857  				return s.constInt16(n.Type(), int16(i))
  2858  			case 4:
  2859  				return s.constInt32(n.Type(), int32(i))
  2860  			case 8:
  2861  				return s.constInt64(n.Type(), i)
  2862  			default:
  2863  				s.Fatalf("bad integer size %d", n.Type().Size())
  2864  				return nil
  2865  			}
  2866  		case constant.String:
  2867  			i := constant.StringVal(u)
  2868  			if i == "" {
  2869  				return s.constEmptyString(n.Type())
  2870  			}
  2871  			return s.entryNewValue0A(ssa.OpConstString, n.Type(), ssa.StringToAux(i))
  2872  		case constant.Bool:
  2873  			return s.constBool(constant.BoolVal(u))
  2874  		case constant.Float:
  2875  			f, _ := constant.Float64Val(u)
  2876  			switch n.Type().Size() {
  2877  			case 4:
  2878  				return s.constFloat32(n.Type(), f)
  2879  			case 8:
  2880  				return s.constFloat64(n.Type(), f)
  2881  			default:
  2882  				s.Fatalf("bad float size %d", n.Type().Size())
  2883  				return nil
  2884  			}
  2885  		case constant.Complex:
  2886  			re, _ := constant.Float64Val(constant.Real(u))
  2887  			im, _ := constant.Float64Val(constant.Imag(u))
  2888  			switch n.Type().Size() {
  2889  			case 8:
  2890  				pt := types.Types[types.TFLOAT32]
  2891  				return s.newValue2(ssa.OpComplexMake, n.Type(),
  2892  					s.constFloat32(pt, re),
  2893  					s.constFloat32(pt, im))
  2894  			case 16:
  2895  				pt := types.Types[types.TFLOAT64]
  2896  				return s.newValue2(ssa.OpComplexMake, n.Type(),
  2897  					s.constFloat64(pt, re),
  2898  					s.constFloat64(pt, im))
  2899  			default:
  2900  				s.Fatalf("bad complex size %d", n.Type().Size())
  2901  				return nil
  2902  			}
  2903  		default:
  2904  			s.Fatalf("unhandled OLITERAL %v", u.Kind())
  2905  			return nil
  2906  		}
  2907  	case ir.OCONVNOP:
  2908  		n := n.(*ir.ConvExpr)
  2909  		to := n.Type()
  2910  		from := n.X.Type()
  2911  
  2912  		// Assume everything will work out, so set up our return value.
  2913  		// Anything interesting that happens from here is a fatal.
  2914  		x := s.expr(n.X)
  2915  		if to == from {
  2916  			return x
  2917  		}
  2918  
  2919  		// Special case for not confusing GC and liveness.
  2920  		// We don't want pointers accidentally classified
  2921  		// as not-pointers or vice-versa because of copy
  2922  		// elision.
  2923  		if to.IsPtrShaped() != from.IsPtrShaped() {
  2924  			return s.newValue2(ssa.OpConvert, to, x, s.mem())
  2925  		}
  2926  
  2927  		v := s.newValue1(ssa.OpCopy, to, x) // ensure that v has the right type
  2928  
  2929  		// CONVNOP closure
  2930  		if to.Kind() == types.TFUNC && from.IsPtrShaped() {
  2931  			return v
  2932  		}
  2933  
  2934  		// named <--> unnamed type or typed <--> untyped const
  2935  		if from.Kind() == to.Kind() {
  2936  			return v
  2937  		}
  2938  
  2939  		// unsafe.Pointer <--> *T
  2940  		if to.IsUnsafePtr() && from.IsPtrShaped() || from.IsUnsafePtr() && to.IsPtrShaped() {
  2941  			if s.checkPtrEnabled && checkPtrOK && to.IsPtr() && from.IsUnsafePtr() {
  2942  				s.checkPtrAlignment(n, v, nil)
  2943  			}
  2944  			return v
  2945  		}
  2946  
  2947  		// map <--> *hmap
  2948  		var mt *types.Type
  2949  		if buildcfg.Experiment.SwissMap {
  2950  			mt = types.NewPtr(reflectdata.SwissMapType())
  2951  		} else {
  2952  			mt = types.NewPtr(reflectdata.OldMapType())
  2953  		}
  2954  		if to.Kind() == types.TMAP && from == mt {
  2955  			return v
  2956  		}
  2957  
  2958  		types.CalcSize(from)
  2959  		types.CalcSize(to)
  2960  		if from.Size() != to.Size() {
  2961  			s.Fatalf("CONVNOP width mismatch %v (%d) -> %v (%d)\n", from, from.Size(), to, to.Size())
  2962  			return nil
  2963  		}
  2964  		if etypesign(from.Kind()) != etypesign(to.Kind()) {
  2965  			s.Fatalf("CONVNOP sign mismatch %v (%s) -> %v (%s)\n", from, from.Kind(), to, to.Kind())
  2966  			return nil
  2967  		}
  2968  
  2969  		if base.Flag.Cfg.Instrumenting {
  2970  			// These appear to be fine, but they fail the
  2971  			// integer constraint below, so okay them here.
  2972  			// Sample non-integer conversion: map[string]string -> *uint8
  2973  			return v
  2974  		}
  2975  
  2976  		if etypesign(from.Kind()) == 0 {
  2977  			s.Fatalf("CONVNOP unrecognized non-integer %v -> %v\n", from, to)
  2978  			return nil
  2979  		}
  2980  
  2981  		// integer, same width, same sign
  2982  		return v
  2983  
  2984  	case ir.OCONV:
  2985  		n := n.(*ir.ConvExpr)
  2986  		x := s.expr(n.X)
  2987  		return s.conv(n, x, n.X.Type(), n.Type())
  2988  
  2989  	case ir.ODOTTYPE:
  2990  		n := n.(*ir.TypeAssertExpr)
  2991  		res, _ := s.dottype(n, false)
  2992  		return res
  2993  
  2994  	case ir.ODYNAMICDOTTYPE:
  2995  		n := n.(*ir.DynamicTypeAssertExpr)
  2996  		res, _ := s.dynamicDottype(n, false)
  2997  		return res
  2998  
  2999  	// binary ops
  3000  	case ir.OLT, ir.OEQ, ir.ONE, ir.OLE, ir.OGE, ir.OGT:
  3001  		n := n.(*ir.BinaryExpr)
  3002  		a := s.expr(n.X)
  3003  		b := s.expr(n.Y)
  3004  		if n.X.Type().IsComplex() {
  3005  			pt := types.FloatForComplex(n.X.Type())
  3006  			op := s.ssaOp(ir.OEQ, pt)
  3007  			r := s.newValueOrSfCall2(op, types.Types[types.TBOOL], s.newValue1(ssa.OpComplexReal, pt, a), s.newValue1(ssa.OpComplexReal, pt, b))
  3008  			i := s.newValueOrSfCall2(op, types.Types[types.TBOOL], s.newValue1(ssa.OpComplexImag, pt, a), s.newValue1(ssa.OpComplexImag, pt, b))
  3009  			c := s.newValue2(ssa.OpAndB, types.Types[types.TBOOL], r, i)
  3010  			switch n.Op() {
  3011  			case ir.OEQ:
  3012  				return c
  3013  			case ir.ONE:
  3014  				return s.newValue1(ssa.OpNot, types.Types[types.TBOOL], c)
  3015  			default:
  3016  				s.Fatalf("ordered complex compare %v", n.Op())
  3017  			}
  3018  		}
  3019  
  3020  		// Convert OGE and OGT into OLE and OLT.
  3021  		op := n.Op()
  3022  		switch op {
  3023  		case ir.OGE:
  3024  			op, a, b = ir.OLE, b, a
  3025  		case ir.OGT:
  3026  			op, a, b = ir.OLT, b, a
  3027  		}
  3028  		if n.X.Type().IsFloat() {
  3029  			// float comparison
  3030  			return s.newValueOrSfCall2(s.ssaOp(op, n.X.Type()), types.Types[types.TBOOL], a, b)
  3031  		}
  3032  		// integer comparison
  3033  		return s.newValue2(s.ssaOp(op, n.X.Type()), types.Types[types.TBOOL], a, b)
  3034  	case ir.OMUL:
  3035  		n := n.(*ir.BinaryExpr)
  3036  		a := s.expr(n.X)
  3037  		b := s.expr(n.Y)
  3038  		if n.Type().IsComplex() {
  3039  			mulop := ssa.OpMul64F
  3040  			addop := ssa.OpAdd64F
  3041  			subop := ssa.OpSub64F
  3042  			pt := types.FloatForComplex(n.Type()) // Could be Float32 or Float64
  3043  			wt := types.Types[types.TFLOAT64]     // Compute in Float64 to minimize cancellation error
  3044  
  3045  			areal := s.newValue1(ssa.OpComplexReal, pt, a)
  3046  			breal := s.newValue1(ssa.OpComplexReal, pt, b)
  3047  			aimag := s.newValue1(ssa.OpComplexImag, pt, a)
  3048  			bimag := s.newValue1(ssa.OpComplexImag, pt, b)
  3049  
  3050  			if pt != wt { // Widen for calculation
  3051  				areal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, areal)
  3052  				breal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, breal)
  3053  				aimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, aimag)
  3054  				bimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, bimag)
  3055  			}
  3056  
  3057  			xreal := s.newValueOrSfCall2(subop, wt, s.newValueOrSfCall2(mulop, wt, areal, breal), s.newValueOrSfCall2(mulop, wt, aimag, bimag))
  3058  			ximag := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, areal, bimag), s.newValueOrSfCall2(mulop, wt, aimag, breal))
  3059  
  3060  			if pt != wt { // Narrow to store back
  3061  				xreal = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, xreal)
  3062  				ximag = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, ximag)
  3063  			}
  3064  
  3065  			return s.newValue2(ssa.OpComplexMake, n.Type(), xreal, ximag)
  3066  		}
  3067  
  3068  		if n.Type().IsFloat() {
  3069  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3070  		}
  3071  
  3072  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3073  
  3074  	case ir.ODIV:
  3075  		n := n.(*ir.BinaryExpr)
  3076  		a := s.expr(n.X)
  3077  		b := s.expr(n.Y)
  3078  		if n.Type().IsComplex() {
  3079  			// TODO this is not executed because the front-end substitutes a runtime call.
  3080  			// That probably ought to change; with modest optimization the widen/narrow
  3081  			// conversions could all be elided in larger expression trees.
  3082  			mulop := ssa.OpMul64F
  3083  			addop := ssa.OpAdd64F
  3084  			subop := ssa.OpSub64F
  3085  			divop := ssa.OpDiv64F
  3086  			pt := types.FloatForComplex(n.Type()) // Could be Float32 or Float64
  3087  			wt := types.Types[types.TFLOAT64]     // Compute in Float64 to minimize cancellation error
  3088  
  3089  			areal := s.newValue1(ssa.OpComplexReal, pt, a)
  3090  			breal := s.newValue1(ssa.OpComplexReal, pt, b)
  3091  			aimag := s.newValue1(ssa.OpComplexImag, pt, a)
  3092  			bimag := s.newValue1(ssa.OpComplexImag, pt, b)
  3093  
  3094  			if pt != wt { // Widen for calculation
  3095  				areal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, areal)
  3096  				breal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, breal)
  3097  				aimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, aimag)
  3098  				bimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, bimag)
  3099  			}
  3100  
  3101  			denom := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, breal, breal), s.newValueOrSfCall2(mulop, wt, bimag, bimag))
  3102  			xreal := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, areal, breal), s.newValueOrSfCall2(mulop, wt, aimag, bimag))
  3103  			ximag := s.newValueOrSfCall2(subop, wt, s.newValueOrSfCall2(mulop, wt, aimag, breal), s.newValueOrSfCall2(mulop, wt, areal, bimag))
  3104  
  3105  			// TODO not sure if this is best done in wide precision or narrow
  3106  			// Double-rounding might be an issue.
  3107  			// Note that the pre-SSA implementation does the entire calculation
  3108  			// in wide format, so wide is compatible.
  3109  			xreal = s.newValueOrSfCall2(divop, wt, xreal, denom)
  3110  			ximag = s.newValueOrSfCall2(divop, wt, ximag, denom)
  3111  
  3112  			if pt != wt { // Narrow to store back
  3113  				xreal = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, xreal)
  3114  				ximag = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, ximag)
  3115  			}
  3116  			return s.newValue2(ssa.OpComplexMake, n.Type(), xreal, ximag)
  3117  		}
  3118  		if n.Type().IsFloat() {
  3119  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3120  		}
  3121  		return s.intDivide(n, a, b)
  3122  	case ir.OMOD:
  3123  		n := n.(*ir.BinaryExpr)
  3124  		a := s.expr(n.X)
  3125  		b := s.expr(n.Y)
  3126  		return s.intDivide(n, a, b)
  3127  	case ir.OADD, ir.OSUB:
  3128  		n := n.(*ir.BinaryExpr)
  3129  		a := s.expr(n.X)
  3130  		b := s.expr(n.Y)
  3131  		if n.Type().IsComplex() {
  3132  			pt := types.FloatForComplex(n.Type())
  3133  			op := s.ssaOp(n.Op(), pt)
  3134  			return s.newValue2(ssa.OpComplexMake, n.Type(),
  3135  				s.newValueOrSfCall2(op, pt, s.newValue1(ssa.OpComplexReal, pt, a), s.newValue1(ssa.OpComplexReal, pt, b)),
  3136  				s.newValueOrSfCall2(op, pt, s.newValue1(ssa.OpComplexImag, pt, a), s.newValue1(ssa.OpComplexImag, pt, b)))
  3137  		}
  3138  		if n.Type().IsFloat() {
  3139  			return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3140  		}
  3141  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3142  	case ir.OAND, ir.OOR, ir.OXOR:
  3143  		n := n.(*ir.BinaryExpr)
  3144  		a := s.expr(n.X)
  3145  		b := s.expr(n.Y)
  3146  		return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  3147  	case ir.OANDNOT:
  3148  		n := n.(*ir.BinaryExpr)
  3149  		a := s.expr(n.X)
  3150  		b := s.expr(n.Y)
  3151  		b = s.newValue1(s.ssaOp(ir.OBITNOT, b.Type), b.Type, b)
  3152  		return s.newValue2(s.ssaOp(ir.OAND, n.Type()), a.Type, a, b)
  3153  	case ir.OLSH, ir.ORSH:
  3154  		n := n.(*ir.BinaryExpr)
  3155  		a := s.expr(n.X)
  3156  		b := s.expr(n.Y)
  3157  		bt := b.Type
  3158  		if bt.IsSigned() {
  3159  			cmp := s.newValue2(s.ssaOp(ir.OLE, bt), types.Types[types.TBOOL], s.zeroVal(bt), b)
  3160  			s.check(cmp, ir.Syms.Panicshift)
  3161  			bt = bt.ToUnsigned()
  3162  		}
  3163  		return s.newValue2(s.ssaShiftOp(n.Op(), n.Type(), bt), a.Type, a, b)
  3164  	case ir.OANDAND, ir.OOROR:
  3165  		// To implement OANDAND (and OOROR), we introduce a
  3166  		// new temporary variable to hold the result. The
  3167  		// variable is associated with the OANDAND node in the
  3168  		// s.vars table (normally variables are only
  3169  		// associated with ONAME nodes). We convert
  3170  		//     A && B
  3171  		// to
  3172  		//     var = A
  3173  		//     if var {
  3174  		//         var = B
  3175  		//     }
  3176  		// Using var in the subsequent block introduces the
  3177  		// necessary phi variable.
  3178  		n := n.(*ir.LogicalExpr)
  3179  		el := s.expr(n.X)
  3180  		s.vars[n] = el
  3181  
  3182  		b := s.endBlock()
  3183  		b.Kind = ssa.BlockIf
  3184  		b.SetControl(el)
  3185  		// In theory, we should set b.Likely here based on context.
  3186  		// However, gc only gives us likeliness hints
  3187  		// in a single place, for plain OIF statements,
  3188  		// and passing around context is finicky, so don't bother for now.
  3189  
  3190  		bRight := s.f.NewBlock(ssa.BlockPlain)
  3191  		bResult := s.f.NewBlock(ssa.BlockPlain)
  3192  		if n.Op() == ir.OANDAND {
  3193  			b.AddEdgeTo(bRight)
  3194  			b.AddEdgeTo(bResult)
  3195  		} else if n.Op() == ir.OOROR {
  3196  			b.AddEdgeTo(bResult)
  3197  			b.AddEdgeTo(bRight)
  3198  		}
  3199  
  3200  		s.startBlock(bRight)
  3201  		er := s.expr(n.Y)
  3202  		s.vars[n] = er
  3203  
  3204  		b = s.endBlock()
  3205  		b.AddEdgeTo(bResult)
  3206  
  3207  		s.startBlock(bResult)
  3208  		return s.variable(n, types.Types[types.TBOOL])
  3209  	case ir.OCOMPLEX:
  3210  		n := n.(*ir.BinaryExpr)
  3211  		r := s.expr(n.X)
  3212  		i := s.expr(n.Y)
  3213  		return s.newValue2(ssa.OpComplexMake, n.Type(), r, i)
  3214  
  3215  	// unary ops
  3216  	case ir.ONEG:
  3217  		n := n.(*ir.UnaryExpr)
  3218  		a := s.expr(n.X)
  3219  		if n.Type().IsComplex() {
  3220  			tp := types.FloatForComplex(n.Type())
  3221  			negop := s.ssaOp(n.Op(), tp)
  3222  			return s.newValue2(ssa.OpComplexMake, n.Type(),
  3223  				s.newValue1(negop, tp, s.newValue1(ssa.OpComplexReal, tp, a)),
  3224  				s.newValue1(negop, tp, s.newValue1(ssa.OpComplexImag, tp, a)))
  3225  		}
  3226  		return s.newValue1(s.ssaOp(n.Op(), n.Type()), a.Type, a)
  3227  	case ir.ONOT, ir.OBITNOT:
  3228  		n := n.(*ir.UnaryExpr)
  3229  		a := s.expr(n.X)
  3230  		return s.newValue1(s.ssaOp(n.Op(), n.Type()), a.Type, a)
  3231  	case ir.OIMAG, ir.OREAL:
  3232  		n := n.(*ir.UnaryExpr)
  3233  		a := s.expr(n.X)
  3234  		return s.newValue1(s.ssaOp(n.Op(), n.X.Type()), n.Type(), a)
  3235  	case ir.OPLUS:
  3236  		n := n.(*ir.UnaryExpr)
  3237  		return s.expr(n.X)
  3238  
  3239  	case ir.OADDR:
  3240  		n := n.(*ir.AddrExpr)
  3241  		return s.addr(n.X)
  3242  
  3243  	case ir.ORESULT:
  3244  		n := n.(*ir.ResultExpr)
  3245  		if s.prevCall == nil || s.prevCall.Op != ssa.OpStaticLECall && s.prevCall.Op != ssa.OpInterLECall && s.prevCall.Op != ssa.OpClosureLECall {
  3246  			panic("Expected to see a previous call")
  3247  		}
  3248  		which := n.Index
  3249  		if which == -1 {
  3250  			panic(fmt.Errorf("ORESULT %v does not match call %s", n, s.prevCall))
  3251  		}
  3252  		return s.resultOfCall(s.prevCall, which, n.Type())
  3253  
  3254  	case ir.ODEREF:
  3255  		n := n.(*ir.StarExpr)
  3256  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  3257  		return s.load(n.Type(), p)
  3258  
  3259  	case ir.ODOT:
  3260  		n := n.(*ir.SelectorExpr)
  3261  		if n.X.Op() == ir.OSTRUCTLIT {
  3262  			// All literals with nonzero fields have already been
  3263  			// rewritten during walk. Any that remain are just T{}
  3264  			// or equivalents. Use the zero value.
  3265  			if !ir.IsZero(n.X) {
  3266  				s.Fatalf("literal with nonzero value in SSA: %v", n.X)
  3267  			}
  3268  			return s.zeroVal(n.Type())
  3269  		}
  3270  		// If n is addressable and can't be represented in
  3271  		// SSA, then load just the selected field. This
  3272  		// prevents false memory dependencies in race/msan/asan
  3273  		// instrumentation.
  3274  		if ir.IsAddressable(n) && !s.canSSA(n) {
  3275  			p := s.addr(n)
  3276  			return s.load(n.Type(), p)
  3277  		}
  3278  		v := s.expr(n.X)
  3279  		return s.newValue1I(ssa.OpStructSelect, n.Type(), int64(fieldIdx(n)), v)
  3280  
  3281  	case ir.ODOTPTR:
  3282  		n := n.(*ir.SelectorExpr)
  3283  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  3284  		p = s.newValue1I(ssa.OpOffPtr, types.NewPtr(n.Type()), n.Offset(), p)
  3285  		return s.load(n.Type(), p)
  3286  
  3287  	case ir.OINDEX:
  3288  		n := n.(*ir.IndexExpr)
  3289  		switch {
  3290  		case n.X.Type().IsString():
  3291  			if n.Bounded() && ir.IsConst(n.X, constant.String) && ir.IsConst(n.Index, constant.Int) {
  3292  				// Replace "abc"[1] with 'b'.
  3293  				// Delayed until now because "abc"[1] is not an ideal constant.
  3294  				// See test/fixedbugs/issue11370.go.
  3295  				return s.newValue0I(ssa.OpConst8, types.Types[types.TUINT8], int64(int8(ir.StringVal(n.X)[ir.Int64Val(n.Index)])))
  3296  			}
  3297  			a := s.expr(n.X)
  3298  			i := s.expr(n.Index)
  3299  			len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], a)
  3300  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  3301  			ptrtyp := s.f.Config.Types.BytePtr
  3302  			ptr := s.newValue1(ssa.OpStringPtr, ptrtyp, a)
  3303  			if ir.IsConst(n.Index, constant.Int) {
  3304  				ptr = s.newValue1I(ssa.OpOffPtr, ptrtyp, ir.Int64Val(n.Index), ptr)
  3305  			} else {
  3306  				ptr = s.newValue2(ssa.OpAddPtr, ptrtyp, ptr, i)
  3307  			}
  3308  			return s.load(types.Types[types.TUINT8], ptr)
  3309  		case n.X.Type().IsSlice():
  3310  			p := s.addr(n)
  3311  			return s.load(n.X.Type().Elem(), p)
  3312  		case n.X.Type().IsArray():
  3313  			if ssa.CanSSA(n.X.Type()) {
  3314  				// SSA can handle arrays of length at most 1.
  3315  				bound := n.X.Type().NumElem()
  3316  				a := s.expr(n.X)
  3317  				i := s.expr(n.Index)
  3318  				if bound == 0 {
  3319  					// Bounds check will never succeed.  Might as well
  3320  					// use constants for the bounds check.
  3321  					z := s.constInt(types.Types[types.TINT], 0)
  3322  					s.boundsCheck(z, z, ssa.BoundsIndex, false)
  3323  					// The return value won't be live, return junk.
  3324  					// But not quite junk, in case bounds checks are turned off. See issue 48092.
  3325  					return s.zeroVal(n.Type())
  3326  				}
  3327  				len := s.constInt(types.Types[types.TINT], bound)
  3328  				s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded()) // checks i == 0
  3329  				return s.newValue1I(ssa.OpArraySelect, n.Type(), 0, a)
  3330  			}
  3331  			p := s.addr(n)
  3332  			return s.load(n.X.Type().Elem(), p)
  3333  		default:
  3334  			s.Fatalf("bad type for index %v", n.X.Type())
  3335  			return nil
  3336  		}
  3337  
  3338  	case ir.OLEN, ir.OCAP:
  3339  		n := n.(*ir.UnaryExpr)
  3340  		switch {
  3341  		case n.X.Type().IsSlice():
  3342  			op := ssa.OpSliceLen
  3343  			if n.Op() == ir.OCAP {
  3344  				op = ssa.OpSliceCap
  3345  			}
  3346  			return s.newValue1(op, types.Types[types.TINT], s.expr(n.X))
  3347  		case n.X.Type().IsString(): // string; not reachable for OCAP
  3348  			return s.newValue1(ssa.OpStringLen, types.Types[types.TINT], s.expr(n.X))
  3349  		case n.X.Type().IsMap(), n.X.Type().IsChan():
  3350  			return s.referenceTypeBuiltin(n, s.expr(n.X))
  3351  		default: // array
  3352  			return s.constInt(types.Types[types.TINT], n.X.Type().NumElem())
  3353  		}
  3354  
  3355  	case ir.OSPTR:
  3356  		n := n.(*ir.UnaryExpr)
  3357  		a := s.expr(n.X)
  3358  		if n.X.Type().IsSlice() {
  3359  			if n.Bounded() {
  3360  				return s.newValue1(ssa.OpSlicePtr, n.Type(), a)
  3361  			}
  3362  			return s.newValue1(ssa.OpSlicePtrUnchecked, n.Type(), a)
  3363  		} else {
  3364  			return s.newValue1(ssa.OpStringPtr, n.Type(), a)
  3365  		}
  3366  
  3367  	case ir.OITAB:
  3368  		n := n.(*ir.UnaryExpr)
  3369  		a := s.expr(n.X)
  3370  		return s.newValue1(ssa.OpITab, n.Type(), a)
  3371  
  3372  	case ir.OIDATA:
  3373  		n := n.(*ir.UnaryExpr)
  3374  		a := s.expr(n.X)
  3375  		return s.newValue1(ssa.OpIData, n.Type(), a)
  3376  
  3377  	case ir.OMAKEFACE:
  3378  		n := n.(*ir.BinaryExpr)
  3379  		tab := s.expr(n.X)
  3380  		data := s.expr(n.Y)
  3381  		return s.newValue2(ssa.OpIMake, n.Type(), tab, data)
  3382  
  3383  	case ir.OSLICEHEADER:
  3384  		n := n.(*ir.SliceHeaderExpr)
  3385  		p := s.expr(n.Ptr)
  3386  		l := s.expr(n.Len)
  3387  		c := s.expr(n.Cap)
  3388  		return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)
  3389  
  3390  	case ir.OSTRINGHEADER:
  3391  		n := n.(*ir.StringHeaderExpr)
  3392  		p := s.expr(n.Ptr)
  3393  		l := s.expr(n.Len)
  3394  		return s.newValue2(ssa.OpStringMake, n.Type(), p, l)
  3395  
  3396  	case ir.OSLICE, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR:
  3397  		n := n.(*ir.SliceExpr)
  3398  		check := s.checkPtrEnabled && n.Op() == ir.OSLICE3ARR && n.X.Op() == ir.OCONVNOP && n.X.(*ir.ConvExpr).X.Type().IsUnsafePtr()
  3399  		v := s.exprCheckPtr(n.X, !check)
  3400  		var i, j, k *ssa.Value
  3401  		if n.Low != nil {
  3402  			i = s.expr(n.Low)
  3403  		}
  3404  		if n.High != nil {
  3405  			j = s.expr(n.High)
  3406  		}
  3407  		if n.Max != nil {
  3408  			k = s.expr(n.Max)
  3409  		}
  3410  		p, l, c := s.slice(v, i, j, k, n.Bounded())
  3411  		if check {
  3412  			// Emit checkptr instrumentation after bound check to prevent false positive, see #46938.
  3413  			s.checkPtrAlignment(n.X.(*ir.ConvExpr), v, s.conv(n.Max, k, k.Type, types.Types[types.TUINTPTR]))
  3414  		}
  3415  		return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)
  3416  
  3417  	case ir.OSLICESTR:
  3418  		n := n.(*ir.SliceExpr)
  3419  		v := s.expr(n.X)
  3420  		var i, j *ssa.Value
  3421  		if n.Low != nil {
  3422  			i = s.expr(n.Low)
  3423  		}
  3424  		if n.High != nil {
  3425  			j = s.expr(n.High)
  3426  		}
  3427  		p, l, _ := s.slice(v, i, j, nil, n.Bounded())
  3428  		return s.newValue2(ssa.OpStringMake, n.Type(), p, l)
  3429  
  3430  	case ir.OSLICE2ARRPTR:
  3431  		// if arrlen > slice.len {
  3432  		//   panic(...)
  3433  		// }
  3434  		// slice.ptr
  3435  		n := n.(*ir.ConvExpr)
  3436  		v := s.expr(n.X)
  3437  		nelem := n.Type().Elem().NumElem()
  3438  		arrlen := s.constInt(types.Types[types.TINT], nelem)
  3439  		cap := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], v)
  3440  		s.boundsCheck(arrlen, cap, ssa.BoundsConvert, false)
  3441  		op := ssa.OpSlicePtr
  3442  		if nelem == 0 {
  3443  			op = ssa.OpSlicePtrUnchecked
  3444  		}
  3445  		return s.newValue1(op, n.Type(), v)
  3446  
  3447  	case ir.OCALLFUNC:
  3448  		n := n.(*ir.CallExpr)
  3449  		if ir.IsIntrinsicCall(n) {
  3450  			return s.intrinsicCall(n)
  3451  		}
  3452  		fallthrough
  3453  
  3454  	case ir.OCALLINTER:
  3455  		n := n.(*ir.CallExpr)
  3456  		return s.callResult(n, callNormal)
  3457  
  3458  	case ir.OGETG:
  3459  		n := n.(*ir.CallExpr)
  3460  		return s.newValue1(ssa.OpGetG, n.Type(), s.mem())
  3461  
  3462  	case ir.OGETCALLERSP:
  3463  		n := n.(*ir.CallExpr)
  3464  		return s.newValue1(ssa.OpGetCallerSP, n.Type(), s.mem())
  3465  
  3466  	case ir.OAPPEND:
  3467  		return s.append(n.(*ir.CallExpr), false)
  3468  
  3469  	case ir.OMIN, ir.OMAX:
  3470  		return s.minMax(n.(*ir.CallExpr))
  3471  
  3472  	case ir.OSTRUCTLIT, ir.OARRAYLIT:
  3473  		// All literals with nonzero fields have already been
  3474  		// rewritten during walk. Any that remain are just T{}
  3475  		// or equivalents. Use the zero value.
  3476  		n := n.(*ir.CompLitExpr)
  3477  		if !ir.IsZero(n) {
  3478  			s.Fatalf("literal with nonzero value in SSA: %v", n)
  3479  		}
  3480  		return s.zeroVal(n.Type())
  3481  
  3482  	case ir.ONEW:
  3483  		n := n.(*ir.UnaryExpr)
  3484  		var rtype *ssa.Value
  3485  		if x, ok := n.X.(*ir.DynamicType); ok && x.Op() == ir.ODYNAMICTYPE {
  3486  			rtype = s.expr(x.RType)
  3487  		}
  3488  		return s.newObject(n.Type().Elem(), rtype)
  3489  
  3490  	case ir.OUNSAFEADD:
  3491  		n := n.(*ir.BinaryExpr)
  3492  		ptr := s.expr(n.X)
  3493  		len := s.expr(n.Y)
  3494  
  3495  		// Force len to uintptr to prevent misuse of garbage bits in the
  3496  		// upper part of the register (#48536).
  3497  		len = s.conv(n, len, len.Type, types.Types[types.TUINTPTR])
  3498  
  3499  		return s.newValue2(ssa.OpAddPtr, n.Type(), ptr, len)
  3500  
  3501  	default:
  3502  		s.Fatalf("unhandled expr %v", n.Op())
  3503  		return nil
  3504  	}
  3505  }
  3506  
  3507  func (s *state) resultOfCall(c *ssa.Value, which int64, t *types.Type) *ssa.Value {
  3508  	aux := c.Aux.(*ssa.AuxCall)
  3509  	pa := aux.ParamAssignmentForResult(which)
  3510  	// TODO(register args) determine if in-memory TypeOK is better loaded early from SelectNAddr or later when SelectN is expanded.
  3511  	// SelectN is better for pattern-matching and possible call-aware analysis we might want to do in the future.
  3512  	if len(pa.Registers) == 0 && !ssa.CanSSA(t) {
  3513  		addr := s.newValue1I(ssa.OpSelectNAddr, types.NewPtr(t), which, c)
  3514  		return s.rawLoad(t, addr)
  3515  	}
  3516  	return s.newValue1I(ssa.OpSelectN, t, which, c)
  3517  }
  3518  
  3519  func (s *state) resultAddrOfCall(c *ssa.Value, which int64, t *types.Type) *ssa.Value {
  3520  	aux := c.Aux.(*ssa.AuxCall)
  3521  	pa := aux.ParamAssignmentForResult(which)
  3522  	if len(pa.Registers) == 0 {
  3523  		return s.newValue1I(ssa.OpSelectNAddr, types.NewPtr(t), which, c)
  3524  	}
  3525  	_, addr := s.temp(c.Pos, t)
  3526  	rval := s.newValue1I(ssa.OpSelectN, t, which, c)
  3527  	s.vars[memVar] = s.newValue3Apos(ssa.OpStore, types.TypeMem, t, addr, rval, s.mem(), false)
  3528  	return addr
  3529  }
  3530  
  3531  // append converts an OAPPEND node to SSA.
  3532  // If inplace is false, it converts the OAPPEND expression n to an ssa.Value,
  3533  // adds it to s, and returns the Value.
  3534  // If inplace is true, it writes the result of the OAPPEND expression n
  3535  // back to the slice being appended to, and returns nil.
  3536  // inplace MUST be set to false if the slice can be SSA'd.
  3537  // Note: this code only handles fixed-count appends. Dotdotdot appends
  3538  // have already been rewritten at this point (by walk).
  3539  func (s *state) append(n *ir.CallExpr, inplace bool) *ssa.Value {
  3540  	// If inplace is false, process as expression "append(s, e1, e2, e3)":
  3541  	//
  3542  	// ptr, len, cap := s
  3543  	// len += 3
  3544  	// if uint(len) > uint(cap) {
  3545  	//     ptr, len, cap = growslice(ptr, len, cap, 3, typ)
  3546  	//     Note that len is unmodified by growslice.
  3547  	// }
  3548  	// // with write barriers, if needed:
  3549  	// *(ptr+(len-3)) = e1
  3550  	// *(ptr+(len-2)) = e2
  3551  	// *(ptr+(len-1)) = e3
  3552  	// return makeslice(ptr, len, cap)
  3553  	//
  3554  	//
  3555  	// If inplace is true, process as statement "s = append(s, e1, e2, e3)":
  3556  	//
  3557  	// a := &s
  3558  	// ptr, len, cap := s
  3559  	// len += 3
  3560  	// if uint(len) > uint(cap) {
  3561  	//    ptr, len, cap = growslice(ptr, len, cap, 3, typ)
  3562  	//    vardef(a)    // if necessary, advise liveness we are writing a new a
  3563  	//    *a.cap = cap // write before ptr to avoid a spill
  3564  	//    *a.ptr = ptr // with write barrier
  3565  	// }
  3566  	// *a.len = len
  3567  	// // with write barriers, if needed:
  3568  	// *(ptr+(len-3)) = e1
  3569  	// *(ptr+(len-2)) = e2
  3570  	// *(ptr+(len-1)) = e3
  3571  
  3572  	et := n.Type().Elem()
  3573  	pt := types.NewPtr(et)
  3574  
  3575  	// Evaluate slice
  3576  	sn := n.Args[0] // the slice node is the first in the list
  3577  	var slice, addr *ssa.Value
  3578  	if inplace {
  3579  		addr = s.addr(sn)
  3580  		slice = s.load(n.Type(), addr)
  3581  	} else {
  3582  		slice = s.expr(sn)
  3583  	}
  3584  
  3585  	// Allocate new blocks
  3586  	grow := s.f.NewBlock(ssa.BlockPlain)
  3587  	assign := s.f.NewBlock(ssa.BlockPlain)
  3588  
  3589  	// Decomposse input slice.
  3590  	p := s.newValue1(ssa.OpSlicePtr, pt, slice)
  3591  	l := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], slice)
  3592  	c := s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], slice)
  3593  
  3594  	// Add number of new elements to length.
  3595  	nargs := s.constInt(types.Types[types.TINT], int64(len(n.Args)-1))
  3596  	l = s.newValue2(s.ssaOp(ir.OADD, types.Types[types.TINT]), types.Types[types.TINT], l, nargs)
  3597  
  3598  	// Decide if we need to grow
  3599  	cmp := s.newValue2(s.ssaOp(ir.OLT, types.Types[types.TUINT]), types.Types[types.TBOOL], c, l)
  3600  
  3601  	// Record values of ptr/len/cap before branch.
  3602  	s.vars[ptrVar] = p
  3603  	s.vars[lenVar] = l
  3604  	if !inplace {
  3605  		s.vars[capVar] = c
  3606  	}
  3607  
  3608  	b := s.endBlock()
  3609  	b.Kind = ssa.BlockIf
  3610  	b.Likely = ssa.BranchUnlikely
  3611  	b.SetControl(cmp)
  3612  	b.AddEdgeTo(grow)
  3613  	b.AddEdgeTo(assign)
  3614  
  3615  	// Call growslice
  3616  	s.startBlock(grow)
  3617  	taddr := s.expr(n.Fun)
  3618  	r := s.rtcall(ir.Syms.Growslice, true, []*types.Type{n.Type()}, p, l, c, nargs, taddr)
  3619  
  3620  	// Decompose output slice
  3621  	p = s.newValue1(ssa.OpSlicePtr, pt, r[0])
  3622  	l = s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], r[0])
  3623  	c = s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], r[0])
  3624  
  3625  	s.vars[ptrVar] = p
  3626  	s.vars[lenVar] = l
  3627  	s.vars[capVar] = c
  3628  	if inplace {
  3629  		if sn.Op() == ir.ONAME {
  3630  			sn := sn.(*ir.Name)
  3631  			if sn.Class != ir.PEXTERN {
  3632  				// Tell liveness we're about to build a new slice
  3633  				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, sn, s.mem())
  3634  			}
  3635  		}
  3636  		capaddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, types.SliceCapOffset, addr)
  3637  		s.store(types.Types[types.TINT], capaddr, c)
  3638  		s.store(pt, addr, p)
  3639  	}
  3640  
  3641  	b = s.endBlock()
  3642  	b.AddEdgeTo(assign)
  3643  
  3644  	// assign new elements to slots
  3645  	s.startBlock(assign)
  3646  	p = s.variable(ptrVar, pt)                      // generates phi for ptr
  3647  	l = s.variable(lenVar, types.Types[types.TINT]) // generates phi for len
  3648  	if !inplace {
  3649  		c = s.variable(capVar, types.Types[types.TINT]) // generates phi for cap
  3650  	}
  3651  
  3652  	if inplace {
  3653  		// Update length in place.
  3654  		// We have to wait until here to make sure growslice succeeded.
  3655  		lenaddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, types.SliceLenOffset, addr)
  3656  		s.store(types.Types[types.TINT], lenaddr, l)
  3657  	}
  3658  
  3659  	// Evaluate args
  3660  	type argRec struct {
  3661  		// if store is true, we're appending the value v.  If false, we're appending the
  3662  		// value at *v.
  3663  		v     *ssa.Value
  3664  		store bool
  3665  	}
  3666  	args := make([]argRec, 0, len(n.Args[1:]))
  3667  	for _, n := range n.Args[1:] {
  3668  		if ssa.CanSSA(n.Type()) {
  3669  			args = append(args, argRec{v: s.expr(n), store: true})
  3670  		} else {
  3671  			v := s.addr(n)
  3672  			args = append(args, argRec{v: v})
  3673  		}
  3674  	}
  3675  
  3676  	// Write args into slice.
  3677  	oldLen := s.newValue2(s.ssaOp(ir.OSUB, types.Types[types.TINT]), types.Types[types.TINT], l, nargs)
  3678  	p2 := s.newValue2(ssa.OpPtrIndex, pt, p, oldLen)
  3679  	for i, arg := range args {
  3680  		addr := s.newValue2(ssa.OpPtrIndex, pt, p2, s.constInt(types.Types[types.TINT], int64(i)))
  3681  		if arg.store {
  3682  			s.storeType(et, addr, arg.v, 0, true)
  3683  		} else {
  3684  			s.move(et, addr, arg.v)
  3685  		}
  3686  	}
  3687  
  3688  	// The following deletions have no practical effect at this time
  3689  	// because state.vars has been reset by the preceding state.startBlock.
  3690  	// They only enforce the fact that these variables are no longer need in
  3691  	// the current scope.
  3692  	delete(s.vars, ptrVar)
  3693  	delete(s.vars, lenVar)
  3694  	if !inplace {
  3695  		delete(s.vars, capVar)
  3696  	}
  3697  
  3698  	// make result
  3699  	if inplace {
  3700  		return nil
  3701  	}
  3702  	return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)
  3703  }
  3704  
  3705  // minMax converts an OMIN/OMAX builtin call into SSA.
  3706  func (s *state) minMax(n *ir.CallExpr) *ssa.Value {
  3707  	// The OMIN/OMAX builtin is variadic, but its semantics are
  3708  	// equivalent to left-folding a binary min/max operation across the
  3709  	// arguments list.
  3710  	fold := func(op func(x, a *ssa.Value) *ssa.Value) *ssa.Value {
  3711  		x := s.expr(n.Args[0])
  3712  		for _, arg := range n.Args[1:] {
  3713  			x = op(x, s.expr(arg))
  3714  		}
  3715  		return x
  3716  	}
  3717  
  3718  	typ := n.Type()
  3719  
  3720  	if typ.IsFloat() || typ.IsString() {
  3721  		// min/max semantics for floats are tricky because of NaNs and
  3722  		// negative zero. Some architectures have instructions which
  3723  		// we can use to generate the right result. For others we must
  3724  		// call into the runtime instead.
  3725  		//
  3726  		// Strings are conceptually simpler, but we currently desugar
  3727  		// string comparisons during walk, not ssagen.
  3728  
  3729  		if typ.IsFloat() {
  3730  			hasIntrinsic := false
  3731  			switch Arch.LinkArch.Family {
  3732  			case sys.AMD64, sys.ARM64, sys.Loong64, sys.RISCV64:
  3733  				hasIntrinsic = true
  3734  			case sys.PPC64:
  3735  				hasIntrinsic = buildcfg.GOPPC64 >= 9
  3736  			}
  3737  
  3738  			if hasIntrinsic {
  3739  				var op ssa.Op
  3740  				switch {
  3741  				case typ.Kind() == types.TFLOAT64 && n.Op() == ir.OMIN:
  3742  					op = ssa.OpMin64F
  3743  				case typ.Kind() == types.TFLOAT64 && n.Op() == ir.OMAX:
  3744  					op = ssa.OpMax64F
  3745  				case typ.Kind() == types.TFLOAT32 && n.Op() == ir.OMIN:
  3746  					op = ssa.OpMin32F
  3747  				case typ.Kind() == types.TFLOAT32 && n.Op() == ir.OMAX:
  3748  					op = ssa.OpMax32F
  3749  				}
  3750  				return fold(func(x, a *ssa.Value) *ssa.Value {
  3751  					return s.newValue2(op, typ, x, a)
  3752  				})
  3753  			}
  3754  		}
  3755  		var name string
  3756  		switch typ.Kind() {
  3757  		case types.TFLOAT32:
  3758  			switch n.Op() {
  3759  			case ir.OMIN:
  3760  				name = "fmin32"
  3761  			case ir.OMAX:
  3762  				name = "fmax32"
  3763  			}
  3764  		case types.TFLOAT64:
  3765  			switch n.Op() {
  3766  			case ir.OMIN:
  3767  				name = "fmin64"
  3768  			case ir.OMAX:
  3769  				name = "fmax64"
  3770  			}
  3771  		case types.TSTRING:
  3772  			switch n.Op() {
  3773  			case ir.OMIN:
  3774  				name = "strmin"
  3775  			case ir.OMAX:
  3776  				name = "strmax"
  3777  			}
  3778  		}
  3779  		fn := typecheck.LookupRuntimeFunc(name)
  3780  
  3781  		return fold(func(x, a *ssa.Value) *ssa.Value {
  3782  			return s.rtcall(fn, true, []*types.Type{typ}, x, a)[0]
  3783  		})
  3784  	}
  3785  
  3786  	if typ.IsInteger() {
  3787  		if Arch.LinkArch.Family == sys.RISCV64 && buildcfg.GORISCV64 >= 22 && typ.Size() == 8 {
  3788  			var op ssa.Op
  3789  			switch {
  3790  			case typ.IsSigned() && n.Op() == ir.OMIN:
  3791  				op = ssa.OpMin64
  3792  			case typ.IsSigned() && n.Op() == ir.OMAX:
  3793  				op = ssa.OpMax64
  3794  			case typ.IsUnsigned() && n.Op() == ir.OMIN:
  3795  				op = ssa.OpMin64u
  3796  			case typ.IsUnsigned() && n.Op() == ir.OMAX:
  3797  				op = ssa.OpMax64u
  3798  			}
  3799  			return fold(func(x, a *ssa.Value) *ssa.Value {
  3800  				return s.newValue2(op, typ, x, a)
  3801  			})
  3802  		}
  3803  	}
  3804  
  3805  	lt := s.ssaOp(ir.OLT, typ)
  3806  
  3807  	return fold(func(x, a *ssa.Value) *ssa.Value {
  3808  		switch n.Op() {
  3809  		case ir.OMIN:
  3810  			// a < x ? a : x
  3811  			return s.ternary(s.newValue2(lt, types.Types[types.TBOOL], a, x), a, x)
  3812  		case ir.OMAX:
  3813  			// x < a ? a : x
  3814  			return s.ternary(s.newValue2(lt, types.Types[types.TBOOL], x, a), a, x)
  3815  		}
  3816  		panic("unreachable")
  3817  	})
  3818  }
  3819  
  3820  // ternary emits code to evaluate cond ? x : y.
  3821  func (s *state) ternary(cond, x, y *ssa.Value) *ssa.Value {
  3822  	// Note that we need a new ternaryVar each time (unlike okVar where we can
  3823  	// reuse the variable) because it might have a different type every time.
  3824  	ternaryVar := ssaMarker("ternary")
  3825  
  3826  	bThen := s.f.NewBlock(ssa.BlockPlain)
  3827  	bElse := s.f.NewBlock(ssa.BlockPlain)
  3828  	bEnd := s.f.NewBlock(ssa.BlockPlain)
  3829  
  3830  	b := s.endBlock()
  3831  	b.Kind = ssa.BlockIf
  3832  	b.SetControl(cond)
  3833  	b.AddEdgeTo(bThen)
  3834  	b.AddEdgeTo(bElse)
  3835  
  3836  	s.startBlock(bThen)
  3837  	s.vars[ternaryVar] = x
  3838  	s.endBlock().AddEdgeTo(bEnd)
  3839  
  3840  	s.startBlock(bElse)
  3841  	s.vars[ternaryVar] = y
  3842  	s.endBlock().AddEdgeTo(bEnd)
  3843  
  3844  	s.startBlock(bEnd)
  3845  	r := s.variable(ternaryVar, x.Type)
  3846  	delete(s.vars, ternaryVar)
  3847  	return r
  3848  }
  3849  
  3850  // condBranch evaluates the boolean expression cond and branches to yes
  3851  // if cond is true and no if cond is false.
  3852  // This function is intended to handle && and || better than just calling
  3853  // s.expr(cond) and branching on the result.
  3854  func (s *state) condBranch(cond ir.Node, yes, no *ssa.Block, likely int8) {
  3855  	switch cond.Op() {
  3856  	case ir.OANDAND:
  3857  		cond := cond.(*ir.LogicalExpr)
  3858  		mid := s.f.NewBlock(ssa.BlockPlain)
  3859  		s.stmtList(cond.Init())
  3860  		s.condBranch(cond.X, mid, no, max(likely, 0))
  3861  		s.startBlock(mid)
  3862  		s.condBranch(cond.Y, yes, no, likely)
  3863  		return
  3864  		// Note: if likely==1, then both recursive calls pass 1.
  3865  		// If likely==-1, then we don't have enough information to decide
  3866  		// whether the first branch is likely or not. So we pass 0 for
  3867  		// the likeliness of the first branch.
  3868  		// TODO: have the frontend give us branch prediction hints for
  3869  		// OANDAND and OOROR nodes (if it ever has such info).
  3870  	case ir.OOROR:
  3871  		cond := cond.(*ir.LogicalExpr)
  3872  		mid := s.f.NewBlock(ssa.BlockPlain)
  3873  		s.stmtList(cond.Init())
  3874  		s.condBranch(cond.X, yes, mid, min(likely, 0))
  3875  		s.startBlock(mid)
  3876  		s.condBranch(cond.Y, yes, no, likely)
  3877  		return
  3878  		// Note: if likely==-1, then both recursive calls pass -1.
  3879  		// If likely==1, then we don't have enough info to decide
  3880  		// the likelihood of the first branch.
  3881  	case ir.ONOT:
  3882  		cond := cond.(*ir.UnaryExpr)
  3883  		s.stmtList(cond.Init())
  3884  		s.condBranch(cond.X, no, yes, -likely)
  3885  		return
  3886  	case ir.OCONVNOP:
  3887  		cond := cond.(*ir.ConvExpr)
  3888  		s.stmtList(cond.Init())
  3889  		s.condBranch(cond.X, yes, no, likely)
  3890  		return
  3891  	}
  3892  	c := s.expr(cond)
  3893  	b := s.endBlock()
  3894  	b.Kind = ssa.BlockIf
  3895  	b.SetControl(c)
  3896  	b.Likely = ssa.BranchPrediction(likely) // gc and ssa both use -1/0/+1 for likeliness
  3897  	b.AddEdgeTo(yes)
  3898  	b.AddEdgeTo(no)
  3899  }
  3900  
  3901  type skipMask uint8
  3902  
  3903  const (
  3904  	skipPtr skipMask = 1 << iota
  3905  	skipLen
  3906  	skipCap
  3907  )
  3908  
  3909  // assign does left = right.
  3910  // Right has already been evaluated to ssa, left has not.
  3911  // If deref is true, then we do left = *right instead (and right has already been nil-checked).
  3912  // If deref is true and right == nil, just do left = 0.
  3913  // skip indicates assignments (at the top level) that can be avoided.
  3914  // mayOverlap indicates whether left&right might partially overlap in memory. Default is false.
  3915  func (s *state) assign(left ir.Node, right *ssa.Value, deref bool, skip skipMask) {
  3916  	s.assignWhichMayOverlap(left, right, deref, skip, false)
  3917  }
  3918  func (s *state) assignWhichMayOverlap(left ir.Node, right *ssa.Value, deref bool, skip skipMask, mayOverlap bool) {
  3919  	if left.Op() == ir.ONAME && ir.IsBlank(left) {
  3920  		return
  3921  	}
  3922  	t := left.Type()
  3923  	types.CalcSize(t)
  3924  	if s.canSSA(left) {
  3925  		if deref {
  3926  			s.Fatalf("can SSA LHS %v but not RHS %s", left, right)
  3927  		}
  3928  		if left.Op() == ir.ODOT {
  3929  			// We're assigning to a field of an ssa-able value.
  3930  			// We need to build a new structure with the new value for the
  3931  			// field we're assigning and the old values for the other fields.
  3932  			// For instance:
  3933  			//   type T struct {a, b, c int}
  3934  			//   var T x
  3935  			//   x.b = 5
  3936  			// For the x.b = 5 assignment we want to generate x = T{x.a, 5, x.c}
  3937  
  3938  			// Grab information about the structure type.
  3939  			left := left.(*ir.SelectorExpr)
  3940  			t := left.X.Type()
  3941  			nf := t.NumFields()
  3942  			idx := fieldIdx(left)
  3943  
  3944  			// Grab old value of structure.
  3945  			old := s.expr(left.X)
  3946  
  3947  			// Make new structure.
  3948  			new := s.newValue0(ssa.OpStructMake, t)
  3949  
  3950  			// Add fields as args.
  3951  			for i := 0; i < nf; i++ {
  3952  				if i == idx {
  3953  					new.AddArg(right)
  3954  				} else {
  3955  					new.AddArg(s.newValue1I(ssa.OpStructSelect, t.FieldType(i), int64(i), old))
  3956  				}
  3957  			}
  3958  
  3959  			// Recursively assign the new value we've made to the base of the dot op.
  3960  			s.assign(left.X, new, false, 0)
  3961  			// TODO: do we need to update named values here?
  3962  			return
  3963  		}
  3964  		if left.Op() == ir.OINDEX && left.(*ir.IndexExpr).X.Type().IsArray() {
  3965  			left := left.(*ir.IndexExpr)
  3966  			s.pushLine(left.Pos())
  3967  			defer s.popLine()
  3968  			// We're assigning to an element of an ssa-able array.
  3969  			// a[i] = v
  3970  			t := left.X.Type()
  3971  			n := t.NumElem()
  3972  
  3973  			i := s.expr(left.Index) // index
  3974  			if n == 0 {
  3975  				// The bounds check must fail.  Might as well
  3976  				// ignore the actual index and just use zeros.
  3977  				z := s.constInt(types.Types[types.TINT], 0)
  3978  				s.boundsCheck(z, z, ssa.BoundsIndex, false)
  3979  				return
  3980  			}
  3981  			if n != 1 {
  3982  				s.Fatalf("assigning to non-1-length array")
  3983  			}
  3984  			// Rewrite to a = [1]{v}
  3985  			len := s.constInt(types.Types[types.TINT], 1)
  3986  			s.boundsCheck(i, len, ssa.BoundsIndex, false) // checks i == 0
  3987  			v := s.newValue1(ssa.OpArrayMake1, t, right)
  3988  			s.assign(left.X, v, false, 0)
  3989  			return
  3990  		}
  3991  		left := left.(*ir.Name)
  3992  		// Update variable assignment.
  3993  		s.vars[left] = right
  3994  		s.addNamedValue(left, right)
  3995  		return
  3996  	}
  3997  
  3998  	// If this assignment clobbers an entire local variable, then emit
  3999  	// OpVarDef so liveness analysis knows the variable is redefined.
  4000  	if base, ok := clobberBase(left).(*ir.Name); ok && base.OnStack() && skip == 0 && (t.HasPointers() || ssa.IsMergeCandidate(base)) {
  4001  		s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, base, s.mem(), !ir.IsAutoTmp(base))
  4002  	}
  4003  
  4004  	// Left is not ssa-able. Compute its address.
  4005  	addr := s.addr(left)
  4006  	if ir.IsReflectHeaderDataField(left) {
  4007  		// Package unsafe's documentation says storing pointers into
  4008  		// reflect.SliceHeader and reflect.StringHeader's Data fields
  4009  		// is valid, even though they have type uintptr (#19168).
  4010  		// Mark it pointer type to signal the writebarrier pass to
  4011  		// insert a write barrier.
  4012  		t = types.Types[types.TUNSAFEPTR]
  4013  	}
  4014  	if deref {
  4015  		// Treat as a mem->mem move.
  4016  		if right == nil {
  4017  			s.zero(t, addr)
  4018  		} else {
  4019  			s.moveWhichMayOverlap(t, addr, right, mayOverlap)
  4020  		}
  4021  		return
  4022  	}
  4023  	// Treat as a store.
  4024  	s.storeType(t, addr, right, skip, !ir.IsAutoTmp(left))
  4025  }
  4026  
  4027  // zeroVal returns the zero value for type t.
  4028  func (s *state) zeroVal(t *types.Type) *ssa.Value {
  4029  	switch {
  4030  	case t.IsInteger():
  4031  		switch t.Size() {
  4032  		case 1:
  4033  			return s.constInt8(t, 0)
  4034  		case 2:
  4035  			return s.constInt16(t, 0)
  4036  		case 4:
  4037  			return s.constInt32(t, 0)
  4038  		case 8:
  4039  			return s.constInt64(t, 0)
  4040  		default:
  4041  			s.Fatalf("bad sized integer type %v", t)
  4042  		}
  4043  	case t.IsFloat():
  4044  		switch t.Size() {
  4045  		case 4:
  4046  			return s.constFloat32(t, 0)
  4047  		case 8:
  4048  			return s.constFloat64(t, 0)
  4049  		default:
  4050  			s.Fatalf("bad sized float type %v", t)
  4051  		}
  4052  	case t.IsComplex():
  4053  		switch t.Size() {
  4054  		case 8:
  4055  			z := s.constFloat32(types.Types[types.TFLOAT32], 0)
  4056  			return s.entryNewValue2(ssa.OpComplexMake, t, z, z)
  4057  		case 16:
  4058  			z := s.constFloat64(types.Types[types.TFLOAT64], 0)
  4059  			return s.entryNewValue2(ssa.OpComplexMake, t, z, z)
  4060  		default:
  4061  			s.Fatalf("bad sized complex type %v", t)
  4062  		}
  4063  
  4064  	case t.IsString():
  4065  		return s.constEmptyString(t)
  4066  	case t.IsPtrShaped():
  4067  		return s.constNil(t)
  4068  	case t.IsBoolean():
  4069  		return s.constBool(false)
  4070  	case t.IsInterface():
  4071  		return s.constInterface(t)
  4072  	case t.IsSlice():
  4073  		return s.constSlice(t)
  4074  	case t.IsStruct():
  4075  		n := t.NumFields()
  4076  		v := s.entryNewValue0(ssa.OpStructMake, t)
  4077  		for i := 0; i < n; i++ {
  4078  			v.AddArg(s.zeroVal(t.FieldType(i)))
  4079  		}
  4080  		return v
  4081  	case t.IsArray():
  4082  		switch t.NumElem() {
  4083  		case 0:
  4084  			return s.entryNewValue0(ssa.OpArrayMake0, t)
  4085  		case 1:
  4086  			return s.entryNewValue1(ssa.OpArrayMake1, t, s.zeroVal(t.Elem()))
  4087  		}
  4088  	}
  4089  	s.Fatalf("zero for type %v not implemented", t)
  4090  	return nil
  4091  }
  4092  
  4093  type callKind int8
  4094  
  4095  const (
  4096  	callNormal callKind = iota
  4097  	callDefer
  4098  	callDeferStack
  4099  	callGo
  4100  	callTail
  4101  )
  4102  
  4103  type sfRtCallDef struct {
  4104  	rtfn  *obj.LSym
  4105  	rtype types.Kind
  4106  }
  4107  
  4108  var softFloatOps map[ssa.Op]sfRtCallDef
  4109  
  4110  func softfloatInit() {
  4111  	// Some of these operations get transformed by sfcall.
  4112  	softFloatOps = map[ssa.Op]sfRtCallDef{
  4113  		ssa.OpAdd32F: {typecheck.LookupRuntimeFunc("fadd32"), types.TFLOAT32},
  4114  		ssa.OpAdd64F: {typecheck.LookupRuntimeFunc("fadd64"), types.TFLOAT64},
  4115  		ssa.OpSub32F: {typecheck.LookupRuntimeFunc("fadd32"), types.TFLOAT32},
  4116  		ssa.OpSub64F: {typecheck.LookupRuntimeFunc("fadd64"), types.TFLOAT64},
  4117  		ssa.OpMul32F: {typecheck.LookupRuntimeFunc("fmul32"), types.TFLOAT32},
  4118  		ssa.OpMul64F: {typecheck.LookupRuntimeFunc("fmul64"), types.TFLOAT64},
  4119  		ssa.OpDiv32F: {typecheck.LookupRuntimeFunc("fdiv32"), types.TFLOAT32},
  4120  		ssa.OpDiv64F: {typecheck.LookupRuntimeFunc("fdiv64"), types.TFLOAT64},
  4121  
  4122  		ssa.OpEq64F:   {typecheck.LookupRuntimeFunc("feq64"), types.TBOOL},
  4123  		ssa.OpEq32F:   {typecheck.LookupRuntimeFunc("feq32"), types.TBOOL},
  4124  		ssa.OpNeq64F:  {typecheck.LookupRuntimeFunc("feq64"), types.TBOOL},
  4125  		ssa.OpNeq32F:  {typecheck.LookupRuntimeFunc("feq32"), types.TBOOL},
  4126  		ssa.OpLess64F: {typecheck.LookupRuntimeFunc("fgt64"), types.TBOOL},
  4127  		ssa.OpLess32F: {typecheck.LookupRuntimeFunc("fgt32"), types.TBOOL},
  4128  		ssa.OpLeq64F:  {typecheck.LookupRuntimeFunc("fge64"), types.TBOOL},
  4129  		ssa.OpLeq32F:  {typecheck.LookupRuntimeFunc("fge32"), types.TBOOL},
  4130  
  4131  		ssa.OpCvt32to32F:  {typecheck.LookupRuntimeFunc("fint32to32"), types.TFLOAT32},
  4132  		ssa.OpCvt32Fto32:  {typecheck.LookupRuntimeFunc("f32toint32"), types.TINT32},
  4133  		ssa.OpCvt64to32F:  {typecheck.LookupRuntimeFunc("fint64to32"), types.TFLOAT32},
  4134  		ssa.OpCvt32Fto64:  {typecheck.LookupRuntimeFunc("f32toint64"), types.TINT64},
  4135  		ssa.OpCvt64Uto32F: {typecheck.LookupRuntimeFunc("fuint64to32"), types.TFLOAT32},
  4136  		ssa.OpCvt32Fto64U: {typecheck.LookupRuntimeFunc("f32touint64"), types.TUINT64},
  4137  		ssa.OpCvt32to64F:  {typecheck.LookupRuntimeFunc("fint32to64"), types.TFLOAT64},
  4138  		ssa.OpCvt64Fto32:  {typecheck.LookupRuntimeFunc("f64toint32"), types.TINT32},
  4139  		ssa.OpCvt64to64F:  {typecheck.LookupRuntimeFunc("fint64to64"), types.TFLOAT64},
  4140  		ssa.OpCvt64Fto64:  {typecheck.LookupRuntimeFunc("f64toint64"), types.TINT64},
  4141  		ssa.OpCvt64Uto64F: {typecheck.LookupRuntimeFunc("fuint64to64"), types.TFLOAT64},
  4142  		ssa.OpCvt64Fto64U: {typecheck.LookupRuntimeFunc("f64touint64"), types.TUINT64},
  4143  		ssa.OpCvt32Fto64F: {typecheck.LookupRuntimeFunc("f32to64"), types.TFLOAT64},
  4144  		ssa.OpCvt64Fto32F: {typecheck.LookupRuntimeFunc("f64to32"), types.TFLOAT32},
  4145  	}
  4146  }
  4147  
  4148  // TODO: do not emit sfcall if operation can be optimized to constant in later
  4149  // opt phase
  4150  func (s *state) sfcall(op ssa.Op, args ...*ssa.Value) (*ssa.Value, bool) {
  4151  	f2i := func(t *types.Type) *types.Type {
  4152  		switch t.Kind() {
  4153  		case types.TFLOAT32:
  4154  			return types.Types[types.TUINT32]
  4155  		case types.TFLOAT64:
  4156  			return types.Types[types.TUINT64]
  4157  		}
  4158  		return t
  4159  	}
  4160  
  4161  	if callDef, ok := softFloatOps[op]; ok {
  4162  		switch op {
  4163  		case ssa.OpLess32F,
  4164  			ssa.OpLess64F,
  4165  			ssa.OpLeq32F,
  4166  			ssa.OpLeq64F:
  4167  			args[0], args[1] = args[1], args[0]
  4168  		case ssa.OpSub32F,
  4169  			ssa.OpSub64F:
  4170  			args[1] = s.newValue1(s.ssaOp(ir.ONEG, types.Types[callDef.rtype]), args[1].Type, args[1])
  4171  		}
  4172  
  4173  		// runtime functions take uints for floats and returns uints.
  4174  		// Convert to uints so we use the right calling convention.
  4175  		for i, a := range args {
  4176  			if a.Type.IsFloat() {
  4177  				args[i] = s.newValue1(ssa.OpCopy, f2i(a.Type), a)
  4178  			}
  4179  		}
  4180  
  4181  		rt := types.Types[callDef.rtype]
  4182  		result := s.rtcall(callDef.rtfn, true, []*types.Type{f2i(rt)}, args...)[0]
  4183  		if rt.IsFloat() {
  4184  			result = s.newValue1(ssa.OpCopy, rt, result)
  4185  		}
  4186  		if op == ssa.OpNeq32F || op == ssa.OpNeq64F {
  4187  			result = s.newValue1(ssa.OpNot, result.Type, result)
  4188  		}
  4189  		return result, true
  4190  	}
  4191  	return nil, false
  4192  }
  4193  
  4194  // split breaks up a tuple-typed value into its 2 parts.
  4195  func (s *state) split(v *ssa.Value) (*ssa.Value, *ssa.Value) {
  4196  	p0 := s.newValue1(ssa.OpSelect0, v.Type.FieldType(0), v)
  4197  	p1 := s.newValue1(ssa.OpSelect1, v.Type.FieldType(1), v)
  4198  	return p0, p1
  4199  }
  4200  
  4201  // intrinsicCall converts a call to a recognized intrinsic function into the intrinsic SSA operation.
  4202  func (s *state) intrinsicCall(n *ir.CallExpr) *ssa.Value {
  4203  	v := findIntrinsic(n.Fun.Sym())(s, n, s.intrinsicArgs(n))
  4204  	if ssa.IntrinsicsDebug > 0 {
  4205  		x := v
  4206  		if x == nil {
  4207  			x = s.mem()
  4208  		}
  4209  		if x.Op == ssa.OpSelect0 || x.Op == ssa.OpSelect1 {
  4210  			x = x.Args[0]
  4211  		}
  4212  		base.WarnfAt(n.Pos(), "intrinsic substitution for %v with %s", n.Fun.Sym().Name, x.LongString())
  4213  	}
  4214  	return v
  4215  }
  4216  
  4217  // intrinsicArgs extracts args from n, evaluates them to SSA values, and returns them.
  4218  func (s *state) intrinsicArgs(n *ir.CallExpr) []*ssa.Value {
  4219  	args := make([]*ssa.Value, len(n.Args))
  4220  	for i, n := range n.Args {
  4221  		args[i] = s.expr(n)
  4222  	}
  4223  	return args
  4224  }
  4225  
  4226  // openDeferRecord adds code to evaluate and store the function for an open-code defer
  4227  // call, and records info about the defer, so we can generate proper code on the
  4228  // exit paths. n is the sub-node of the defer node that is the actual function
  4229  // call. We will also record funcdata information on where the function is stored
  4230  // (as well as the deferBits variable), and this will enable us to run the proper
  4231  // defer calls during panics.
  4232  func (s *state) openDeferRecord(n *ir.CallExpr) {
  4233  	if len(n.Args) != 0 || n.Op() != ir.OCALLFUNC || n.Fun.Type().NumResults() != 0 {
  4234  		s.Fatalf("defer call with arguments or results: %v", n)
  4235  	}
  4236  
  4237  	opendefer := &openDeferInfo{
  4238  		n: n,
  4239  	}
  4240  	fn := n.Fun
  4241  	// We must always store the function value in a stack slot for the
  4242  	// runtime panic code to use. But in the defer exit code, we will
  4243  	// call the function directly if it is a static function.
  4244  	closureVal := s.expr(fn)
  4245  	closure := s.openDeferSave(fn.Type(), closureVal)
  4246  	opendefer.closureNode = closure.Aux.(*ir.Name)
  4247  	if !(fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC) {
  4248  		opendefer.closure = closure
  4249  	}
  4250  	index := len(s.openDefers)
  4251  	s.openDefers = append(s.openDefers, opendefer)
  4252  
  4253  	// Update deferBits only after evaluation and storage to stack of
  4254  	// the function is successful.
  4255  	bitvalue := s.constInt8(types.Types[types.TUINT8], 1<<uint(index))
  4256  	newDeferBits := s.newValue2(ssa.OpOr8, types.Types[types.TUINT8], s.variable(deferBitsVar, types.Types[types.TUINT8]), bitvalue)
  4257  	s.vars[deferBitsVar] = newDeferBits
  4258  	s.store(types.Types[types.TUINT8], s.deferBitsAddr, newDeferBits)
  4259  }
  4260  
  4261  // openDeferSave generates SSA nodes to store a value (with type t) for an
  4262  // open-coded defer at an explicit autotmp location on the stack, so it can be
  4263  // reloaded and used for the appropriate call on exit. Type t must be a function type
  4264  // (therefore SSAable). val is the value to be stored. The function returns an SSA
  4265  // value representing a pointer to the autotmp location.
  4266  func (s *state) openDeferSave(t *types.Type, val *ssa.Value) *ssa.Value {
  4267  	if !ssa.CanSSA(t) {
  4268  		s.Fatalf("openDeferSave of non-SSA-able type %v val=%v", t, val)
  4269  	}
  4270  	if !t.HasPointers() {
  4271  		s.Fatalf("openDeferSave of pointerless type %v val=%v", t, val)
  4272  	}
  4273  	pos := val.Pos
  4274  	temp := typecheck.TempAt(pos.WithNotStmt(), s.curfn, t)
  4275  	temp.SetOpenDeferSlot(true)
  4276  	temp.SetFrameOffset(int64(len(s.openDefers))) // so cmpstackvarlt can order them
  4277  	var addrTemp *ssa.Value
  4278  	// Use OpVarLive to make sure stack slot for the closure is not removed by
  4279  	// dead-store elimination
  4280  	if s.curBlock.ID != s.f.Entry.ID {
  4281  		// Force the tmp storing this defer function to be declared in the entry
  4282  		// block, so that it will be live for the defer exit code (which will
  4283  		// actually access it only if the associated defer call has been activated).
  4284  		if t.HasPointers() {
  4285  			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])
  4286  		}
  4287  		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])
  4288  		addrTemp = s.f.Entry.NewValue2A(src.NoXPos, ssa.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.defvars[s.f.Entry.ID][memVar])
  4289  	} else {
  4290  		// Special case if we're still in the entry block. We can't use
  4291  		// the above code, since s.defvars[s.f.Entry.ID] isn't defined
  4292  		// until we end the entry block with s.endBlock().
  4293  		if t.HasPointers() {
  4294  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, temp, s.mem(), false)
  4295  		}
  4296  		s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, temp, s.mem(), false)
  4297  		addrTemp = s.newValue2Apos(ssa.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.mem(), false)
  4298  	}
  4299  	// Since we may use this temp during exit depending on the
  4300  	// deferBits, we must define it unconditionally on entry.
  4301  	// Therefore, we must make sure it is zeroed out in the entry
  4302  	// block if it contains pointers, else GC may wrongly follow an
  4303  	// uninitialized pointer value.
  4304  	temp.SetNeedzero(true)
  4305  	// We are storing to the stack, hence we can avoid the full checks in
  4306  	// storeType() (no write barrier) and do a simple store().
  4307  	s.store(t, addrTemp, val)
  4308  	return addrTemp
  4309  }
  4310  
  4311  // openDeferExit generates SSA for processing all the open coded defers at exit.
  4312  // The code involves loading deferBits, and checking each of the bits to see if
  4313  // the corresponding defer statement was executed. For each bit that is turned
  4314  // on, the associated defer call is made.
  4315  func (s *state) openDeferExit() {
  4316  	deferExit := s.f.NewBlock(ssa.BlockPlain)
  4317  	s.endBlock().AddEdgeTo(deferExit)
  4318  	s.startBlock(deferExit)
  4319  	s.lastDeferExit = deferExit
  4320  	s.lastDeferCount = len(s.openDefers)
  4321  	zeroval := s.constInt8(types.Types[types.TUINT8], 0)
  4322  	// Test for and run defers in reverse order
  4323  	for i := len(s.openDefers) - 1; i >= 0; i-- {
  4324  		r := s.openDefers[i]
  4325  		bCond := s.f.NewBlock(ssa.BlockPlain)
  4326  		bEnd := s.f.NewBlock(ssa.BlockPlain)
  4327  
  4328  		deferBits := s.variable(deferBitsVar, types.Types[types.TUINT8])
  4329  		// Generate code to check if the bit associated with the current
  4330  		// defer is set.
  4331  		bitval := s.constInt8(types.Types[types.TUINT8], 1<<uint(i))
  4332  		andval := s.newValue2(ssa.OpAnd8, types.Types[types.TUINT8], deferBits, bitval)
  4333  		eqVal := s.newValue2(ssa.OpEq8, types.Types[types.TBOOL], andval, zeroval)
  4334  		b := s.endBlock()
  4335  		b.Kind = ssa.BlockIf
  4336  		b.SetControl(eqVal)
  4337  		b.AddEdgeTo(bEnd)
  4338  		b.AddEdgeTo(bCond)
  4339  		bCond.AddEdgeTo(bEnd)
  4340  		s.startBlock(bCond)
  4341  
  4342  		// Clear this bit in deferBits and force store back to stack, so
  4343  		// we will not try to re-run this defer call if this defer call panics.
  4344  		nbitval := s.newValue1(ssa.OpCom8, types.Types[types.TUINT8], bitval)
  4345  		maskedval := s.newValue2(ssa.OpAnd8, types.Types[types.TUINT8], deferBits, nbitval)
  4346  		s.store(types.Types[types.TUINT8], s.deferBitsAddr, maskedval)
  4347  		// Use this value for following tests, so we keep previous
  4348  		// bits cleared.
  4349  		s.vars[deferBitsVar] = maskedval
  4350  
  4351  		// Generate code to call the function call of the defer, using the
  4352  		// closure that were stored in argtmps at the point of the defer
  4353  		// statement.
  4354  		fn := r.n.Fun
  4355  		stksize := fn.Type().ArgWidth()
  4356  		var callArgs []*ssa.Value
  4357  		var call *ssa.Value
  4358  		if r.closure != nil {
  4359  			v := s.load(r.closure.Type.Elem(), r.closure)
  4360  			s.maybeNilCheckClosure(v, callDefer)
  4361  			codeptr := s.rawLoad(types.Types[types.TUINTPTR], v)
  4362  			aux := ssa.ClosureAuxCall(s.f.ABIDefault.ABIAnalyzeTypes(nil, nil))
  4363  			call = s.newValue2A(ssa.OpClosureLECall, aux.LateExpansionResultType(), aux, codeptr, v)
  4364  		} else {
  4365  			aux := ssa.StaticAuxCall(fn.(*ir.Name).Linksym(), s.f.ABIDefault.ABIAnalyzeTypes(nil, nil))
  4366  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4367  		}
  4368  		callArgs = append(callArgs, s.mem())
  4369  		call.AddArgs(callArgs...)
  4370  		call.AuxInt = stksize
  4371  		s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, 0, call)
  4372  		// Make sure that the stack slots with pointers are kept live
  4373  		// through the call (which is a pre-emption point). Also, we will
  4374  		// use the first call of the last defer exit to compute liveness
  4375  		// for the deferreturn, so we want all stack slots to be live.
  4376  		if r.closureNode != nil {
  4377  			s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, r.closureNode, s.mem(), false)
  4378  		}
  4379  
  4380  		s.endBlock()
  4381  		s.startBlock(bEnd)
  4382  	}
  4383  }
  4384  
  4385  func (s *state) callResult(n *ir.CallExpr, k callKind) *ssa.Value {
  4386  	return s.call(n, k, false, nil)
  4387  }
  4388  
  4389  func (s *state) callAddr(n *ir.CallExpr, k callKind) *ssa.Value {
  4390  	return s.call(n, k, true, nil)
  4391  }
  4392  
  4393  // Calls the function n using the specified call type.
  4394  // Returns the address of the return value (or nil if none).
  4395  func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool, deferExtra ir.Expr) *ssa.Value {
  4396  	s.prevCall = nil
  4397  	var calleeLSym *obj.LSym // target function (if static)
  4398  	var closure *ssa.Value   // ptr to closure to run (if dynamic)
  4399  	var codeptr *ssa.Value   // ptr to target code (if dynamic)
  4400  	var dextra *ssa.Value    // defer extra arg
  4401  	var rcvr *ssa.Value      // receiver to set
  4402  	fn := n.Fun
  4403  	var ACArgs []*types.Type    // AuxCall args
  4404  	var ACResults []*types.Type // AuxCall results
  4405  	var callArgs []*ssa.Value   // For late-expansion, the args themselves (not stored, args to the call instead).
  4406  
  4407  	callABI := s.f.ABIDefault
  4408  
  4409  	if k != callNormal && k != callTail && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.Fun.Type().NumResults() != 0) {
  4410  		s.Fatalf("go/defer call with arguments: %v", n)
  4411  	}
  4412  
  4413  	switch n.Op() {
  4414  	case ir.OCALLFUNC:
  4415  		if (k == callNormal || k == callTail) && fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC {
  4416  			fn := fn.(*ir.Name)
  4417  			calleeLSym = callTargetLSym(fn)
  4418  			if buildcfg.Experiment.RegabiArgs {
  4419  				// This is a static call, so it may be
  4420  				// a direct call to a non-ABIInternal
  4421  				// function. fn.Func may be nil for
  4422  				// some compiler-generated functions,
  4423  				// but those are all ABIInternal.
  4424  				if fn.Func != nil {
  4425  					callABI = abiForFunc(fn.Func, s.f.ABI0, s.f.ABI1)
  4426  				}
  4427  			} else {
  4428  				// TODO(register args) remove after register abi is working
  4429  				inRegistersImported := fn.Pragma()&ir.RegisterParams != 0
  4430  				inRegistersSamePackage := fn.Func != nil && fn.Func.Pragma&ir.RegisterParams != 0
  4431  				if inRegistersImported || inRegistersSamePackage {
  4432  					callABI = s.f.ABI1
  4433  				}
  4434  			}
  4435  			break
  4436  		}
  4437  		closure = s.expr(fn)
  4438  		if k != callDefer && k != callDeferStack {
  4439  			// Deferred nil function needs to panic when the function is invoked,
  4440  			// not the point of defer statement.
  4441  			s.maybeNilCheckClosure(closure, k)
  4442  		}
  4443  	case ir.OCALLINTER:
  4444  		if fn.Op() != ir.ODOTINTER {
  4445  			s.Fatalf("OCALLINTER: n.Left not an ODOTINTER: %v", fn.Op())
  4446  		}
  4447  		fn := fn.(*ir.SelectorExpr)
  4448  		var iclosure *ssa.Value
  4449  		iclosure, rcvr = s.getClosureAndRcvr(fn)
  4450  		if k == callNormal {
  4451  			codeptr = s.load(types.Types[types.TUINTPTR], iclosure)
  4452  		} else {
  4453  			closure = iclosure
  4454  		}
  4455  	}
  4456  	if deferExtra != nil {
  4457  		dextra = s.expr(deferExtra)
  4458  	}
  4459  
  4460  	params := callABI.ABIAnalyze(n.Fun.Type(), false /* Do not set (register) nNames from caller side -- can cause races. */)
  4461  	types.CalcSize(fn.Type())
  4462  	stksize := params.ArgWidth() // includes receiver, args, and results
  4463  
  4464  	res := n.Fun.Type().Results()
  4465  	if k == callNormal || k == callTail {
  4466  		for _, p := range params.OutParams() {
  4467  			ACResults = append(ACResults, p.Type)
  4468  		}
  4469  	}
  4470  
  4471  	var call *ssa.Value
  4472  	if k == callDeferStack {
  4473  		if stksize != 0 {
  4474  			s.Fatalf("deferprocStack with non-zero stack size %d: %v", stksize, n)
  4475  		}
  4476  		// Make a defer struct on the stack.
  4477  		t := deferstruct()
  4478  		n, addr := s.temp(n.Pos(), t)
  4479  		n.SetNonMergeable(true)
  4480  		s.store(closure.Type,
  4481  			s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(deferStructFnField), addr),
  4482  			closure)
  4483  
  4484  		// Call runtime.deferprocStack with pointer to _defer record.
  4485  		ACArgs = append(ACArgs, types.Types[types.TUINTPTR])
  4486  		aux := ssa.StaticAuxCall(ir.Syms.DeferprocStack, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults))
  4487  		callArgs = append(callArgs, addr, s.mem())
  4488  		call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4489  		call.AddArgs(callArgs...)
  4490  		call.AuxInt = int64(types.PtrSize) // deferprocStack takes a *_defer arg
  4491  	} else {
  4492  		// Store arguments to stack, including defer/go arguments and receiver for method calls.
  4493  		// These are written in SP-offset order.
  4494  		argStart := base.Ctxt.Arch.FixedFrameSize
  4495  		// Defer/go args.
  4496  		if k != callNormal && k != callTail {
  4497  			// Write closure (arg to newproc/deferproc).
  4498  			ACArgs = append(ACArgs, types.Types[types.TUINTPTR]) // not argExtra
  4499  			callArgs = append(callArgs, closure)
  4500  			stksize += int64(types.PtrSize)
  4501  			argStart += int64(types.PtrSize)
  4502  			if dextra != nil {
  4503  				// Extra token of type any for deferproc
  4504  				ACArgs = append(ACArgs, types.Types[types.TINTER])
  4505  				callArgs = append(callArgs, dextra)
  4506  				stksize += 2 * int64(types.PtrSize)
  4507  				argStart += 2 * int64(types.PtrSize)
  4508  			}
  4509  		}
  4510  
  4511  		// Set receiver (for interface calls).
  4512  		if rcvr != nil {
  4513  			callArgs = append(callArgs, rcvr)
  4514  		}
  4515  
  4516  		// Write args.
  4517  		t := n.Fun.Type()
  4518  		args := n.Args
  4519  
  4520  		for _, p := range params.InParams() { // includes receiver for interface calls
  4521  			ACArgs = append(ACArgs, p.Type)
  4522  		}
  4523  
  4524  		// Split the entry block if there are open defers, because later calls to
  4525  		// openDeferSave may cause a mismatch between the mem for an OpDereference
  4526  		// and the call site which uses it. See #49282.
  4527  		if s.curBlock.ID == s.f.Entry.ID && s.hasOpenDefers {
  4528  			b := s.endBlock()
  4529  			b.Kind = ssa.BlockPlain
  4530  			curb := s.f.NewBlock(ssa.BlockPlain)
  4531  			b.AddEdgeTo(curb)
  4532  			s.startBlock(curb)
  4533  		}
  4534  
  4535  		for i, n := range args {
  4536  			callArgs = append(callArgs, s.putArg(n, t.Param(i).Type))
  4537  		}
  4538  
  4539  		callArgs = append(callArgs, s.mem())
  4540  
  4541  		// call target
  4542  		switch {
  4543  		case k == callDefer:
  4544  			sym := ir.Syms.Deferproc
  4545  			if dextra != nil {
  4546  				sym = ir.Syms.Deferprocat
  4547  			}
  4548  			aux := ssa.StaticAuxCall(sym, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults)) // TODO paramResultInfo for Deferproc(at)
  4549  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4550  		case k == callGo:
  4551  			aux := ssa.StaticAuxCall(ir.Syms.Newproc, s.f.ABIDefault.ABIAnalyzeTypes(ACArgs, ACResults))
  4552  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux) // TODO paramResultInfo for Newproc
  4553  		case closure != nil:
  4554  			// rawLoad because loading the code pointer from a
  4555  			// closure is always safe, but IsSanitizerSafeAddr
  4556  			// can't always figure that out currently, and it's
  4557  			// critical that we not clobber any arguments already
  4558  			// stored onto the stack.
  4559  			codeptr = s.rawLoad(types.Types[types.TUINTPTR], closure)
  4560  			aux := ssa.ClosureAuxCall(callABI.ABIAnalyzeTypes(ACArgs, ACResults))
  4561  			call = s.newValue2A(ssa.OpClosureLECall, aux.LateExpansionResultType(), aux, codeptr, closure)
  4562  		case codeptr != nil:
  4563  			// Note that the "receiver" parameter is nil because the actual receiver is the first input parameter.
  4564  			aux := ssa.InterfaceAuxCall(params)
  4565  			call = s.newValue1A(ssa.OpInterLECall, aux.LateExpansionResultType(), aux, codeptr)
  4566  		case calleeLSym != nil:
  4567  			aux := ssa.StaticAuxCall(calleeLSym, params)
  4568  			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  4569  			if k == callTail {
  4570  				call.Op = ssa.OpTailLECall
  4571  				stksize = 0 // Tail call does not use stack. We reuse caller's frame.
  4572  			}
  4573  		default:
  4574  			s.Fatalf("bad call type %v %v", n.Op(), n)
  4575  		}
  4576  		call.AddArgs(callArgs...)
  4577  		call.AuxInt = stksize // Call operations carry the argsize of the callee along with them
  4578  	}
  4579  	s.prevCall = call
  4580  	s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, int64(len(ACResults)), call)
  4581  	// Insert VarLive opcodes.
  4582  	for _, v := range n.KeepAlive {
  4583  		if !v.Addrtaken() {
  4584  			s.Fatalf("KeepAlive variable %v must have Addrtaken set", v)
  4585  		}
  4586  		switch v.Class {
  4587  		case ir.PAUTO, ir.PPARAM, ir.PPARAMOUT:
  4588  		default:
  4589  			s.Fatalf("KeepAlive variable %v must be Auto or Arg", v)
  4590  		}
  4591  		s.vars[memVar] = s.newValue1A(ssa.OpVarLive, types.TypeMem, v, s.mem())
  4592  	}
  4593  
  4594  	// Finish block for defers
  4595  	if k == callDefer || k == callDeferStack {
  4596  		b := s.endBlock()
  4597  		b.Kind = ssa.BlockDefer
  4598  		b.SetControl(call)
  4599  		bNext := s.f.NewBlock(ssa.BlockPlain)
  4600  		b.AddEdgeTo(bNext)
  4601  		// Add recover edge to exit code.
  4602  		r := s.f.NewBlock(ssa.BlockPlain)
  4603  		s.startBlock(r)
  4604  		s.exit()
  4605  		b.AddEdgeTo(r)
  4606  		b.Likely = ssa.BranchLikely
  4607  		s.startBlock(bNext)
  4608  	}
  4609  
  4610  	if len(res) == 0 || k != callNormal {
  4611  		// call has no return value. Continue with the next statement.
  4612  		return nil
  4613  	}
  4614  	fp := res[0]
  4615  	if returnResultAddr {
  4616  		return s.resultAddrOfCall(call, 0, fp.Type)
  4617  	}
  4618  	return s.newValue1I(ssa.OpSelectN, fp.Type, 0, call)
  4619  }
  4620  
  4621  // maybeNilCheckClosure checks if a nil check of a closure is needed in some
  4622  // architecture-dependent situations and, if so, emits the nil check.
  4623  func (s *state) maybeNilCheckClosure(closure *ssa.Value, k callKind) {
  4624  	if Arch.LinkArch.Family == sys.Wasm || buildcfg.GOOS == "aix" && k != callGo {
  4625  		// 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.
  4626  		// TODO(neelance): On other architectures this should be eliminated by the optimization steps
  4627  		s.nilCheck(closure)
  4628  	}
  4629  }
  4630  
  4631  // getClosureAndRcvr returns values for the appropriate closure and receiver of an
  4632  // interface call
  4633  func (s *state) getClosureAndRcvr(fn *ir.SelectorExpr) (*ssa.Value, *ssa.Value) {
  4634  	i := s.expr(fn.X)
  4635  	itab := s.newValue1(ssa.OpITab, types.Types[types.TUINTPTR], i)
  4636  	s.nilCheck(itab)
  4637  	itabidx := fn.Offset() + rttype.ITab.OffsetOf("Fun")
  4638  	closure := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.UintptrPtr, itabidx, itab)
  4639  	rcvr := s.newValue1(ssa.OpIData, s.f.Config.Types.BytePtr, i)
  4640  	return closure, rcvr
  4641  }
  4642  
  4643  // etypesign returns the signed-ness of e, for integer/pointer etypes.
  4644  // -1 means signed, +1 means unsigned, 0 means non-integer/non-pointer.
  4645  func etypesign(e types.Kind) int8 {
  4646  	switch e {
  4647  	case types.TINT8, types.TINT16, types.TINT32, types.TINT64, types.TINT:
  4648  		return -1
  4649  	case types.TUINT8, types.TUINT16, types.TUINT32, types.TUINT64, types.TUINT, types.TUINTPTR, types.TUNSAFEPTR:
  4650  		return +1
  4651  	}
  4652  	return 0
  4653  }
  4654  
  4655  // addr converts the address of the expression n to SSA, adds it to s and returns the SSA result.
  4656  // The value that the returned Value represents is guaranteed to be non-nil.
  4657  func (s *state) addr(n ir.Node) *ssa.Value {
  4658  	if n.Op() != ir.ONAME {
  4659  		s.pushLine(n.Pos())
  4660  		defer s.popLine()
  4661  	}
  4662  
  4663  	if s.canSSA(n) {
  4664  		s.Fatalf("addr of canSSA expression: %+v", n)
  4665  	}
  4666  
  4667  	t := types.NewPtr(n.Type())
  4668  	linksymOffset := func(lsym *obj.LSym, offset int64) *ssa.Value {
  4669  		v := s.entryNewValue1A(ssa.OpAddr, t, lsym, s.sb)
  4670  		// TODO: Make OpAddr use AuxInt as well as Aux.
  4671  		if offset != 0 {
  4672  			v = s.entryNewValue1I(ssa.OpOffPtr, v.Type, offset, v)
  4673  		}
  4674  		return v
  4675  	}
  4676  	switch n.Op() {
  4677  	case ir.OLINKSYMOFFSET:
  4678  		no := n.(*ir.LinksymOffsetExpr)
  4679  		return linksymOffset(no.Linksym, no.Offset_)
  4680  	case ir.ONAME:
  4681  		n := n.(*ir.Name)
  4682  		if n.Heapaddr != nil {
  4683  			return s.expr(n.Heapaddr)
  4684  		}
  4685  		switch n.Class {
  4686  		case ir.PEXTERN:
  4687  			// global variable
  4688  			return linksymOffset(n.Linksym(), 0)
  4689  		case ir.PPARAM:
  4690  			// parameter slot
  4691  			v := s.decladdrs[n]
  4692  			if v != nil {
  4693  				return v
  4694  			}
  4695  			s.Fatalf("addr of undeclared ONAME %v. declared: %v", n, s.decladdrs)
  4696  			return nil
  4697  		case ir.PAUTO:
  4698  			return s.newValue2Apos(ssa.OpLocalAddr, t, n, s.sp, s.mem(), !ir.IsAutoTmp(n))
  4699  
  4700  		case ir.PPARAMOUT: // Same as PAUTO -- cannot generate LEA early.
  4701  			// ensure that we reuse symbols for out parameters so
  4702  			// that cse works on their addresses
  4703  			return s.newValue2Apos(ssa.OpLocalAddr, t, n, s.sp, s.mem(), true)
  4704  		default:
  4705  			s.Fatalf("variable address class %v not implemented", n.Class)
  4706  			return nil
  4707  		}
  4708  	case ir.ORESULT:
  4709  		// load return from callee
  4710  		n := n.(*ir.ResultExpr)
  4711  		return s.resultAddrOfCall(s.prevCall, n.Index, n.Type())
  4712  	case ir.OINDEX:
  4713  		n := n.(*ir.IndexExpr)
  4714  		if n.X.Type().IsSlice() {
  4715  			a := s.expr(n.X)
  4716  			i := s.expr(n.Index)
  4717  			len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], a)
  4718  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  4719  			p := s.newValue1(ssa.OpSlicePtr, t, a)
  4720  			return s.newValue2(ssa.OpPtrIndex, t, p, i)
  4721  		} else { // array
  4722  			a := s.addr(n.X)
  4723  			i := s.expr(n.Index)
  4724  			len := s.constInt(types.Types[types.TINT], n.X.Type().NumElem())
  4725  			i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
  4726  			return s.newValue2(ssa.OpPtrIndex, types.NewPtr(n.X.Type().Elem()), a, i)
  4727  		}
  4728  	case ir.ODEREF:
  4729  		n := n.(*ir.StarExpr)
  4730  		return s.exprPtr(n.X, n.Bounded(), n.Pos())
  4731  	case ir.ODOT:
  4732  		n := n.(*ir.SelectorExpr)
  4733  		p := s.addr(n.X)
  4734  		return s.newValue1I(ssa.OpOffPtr, t, n.Offset(), p)
  4735  	case ir.ODOTPTR:
  4736  		n := n.(*ir.SelectorExpr)
  4737  		p := s.exprPtr(n.X, n.Bounded(), n.Pos())
  4738  		return s.newValue1I(ssa.OpOffPtr, t, n.Offset(), p)
  4739  	case ir.OCONVNOP:
  4740  		n := n.(*ir.ConvExpr)
  4741  		if n.Type() == n.X.Type() {
  4742  			return s.addr(n.X)
  4743  		}
  4744  		addr := s.addr(n.X)
  4745  		return s.newValue1(ssa.OpCopy, t, addr) // ensure that addr has the right type
  4746  	case ir.OCALLFUNC, ir.OCALLINTER:
  4747  		n := n.(*ir.CallExpr)
  4748  		return s.callAddr(n, callNormal)
  4749  	case ir.ODOTTYPE, ir.ODYNAMICDOTTYPE:
  4750  		var v *ssa.Value
  4751  		if n.Op() == ir.ODOTTYPE {
  4752  			v, _ = s.dottype(n.(*ir.TypeAssertExpr), false)
  4753  		} else {
  4754  			v, _ = s.dynamicDottype(n.(*ir.DynamicTypeAssertExpr), false)
  4755  		}
  4756  		if v.Op != ssa.OpLoad {
  4757  			s.Fatalf("dottype of non-load")
  4758  		}
  4759  		if v.Args[1] != s.mem() {
  4760  			s.Fatalf("memory no longer live from dottype load")
  4761  		}
  4762  		return v.Args[0]
  4763  	default:
  4764  		s.Fatalf("unhandled addr %v", n.Op())
  4765  		return nil
  4766  	}
  4767  }
  4768  
  4769  // canSSA reports whether n is SSA-able.
  4770  // n must be an ONAME (or an ODOT sequence with an ONAME base).
  4771  func (s *state) canSSA(n ir.Node) bool {
  4772  	if base.Flag.N != 0 {
  4773  		return false
  4774  	}
  4775  	for {
  4776  		nn := n
  4777  		if nn.Op() == ir.ODOT {
  4778  			nn := nn.(*ir.SelectorExpr)
  4779  			n = nn.X
  4780  			continue
  4781  		}
  4782  		if nn.Op() == ir.OINDEX {
  4783  			nn := nn.(*ir.IndexExpr)
  4784  			if nn.X.Type().IsArray() {
  4785  				n = nn.X
  4786  				continue
  4787  			}
  4788  		}
  4789  		break
  4790  	}
  4791  	if n.Op() != ir.ONAME {
  4792  		return false
  4793  	}
  4794  	return s.canSSAName(n.(*ir.Name)) && ssa.CanSSA(n.Type())
  4795  }
  4796  
  4797  func (s *state) canSSAName(name *ir.Name) bool {
  4798  	if name.Addrtaken() || !name.OnStack() {
  4799  		return false
  4800  	}
  4801  	switch name.Class {
  4802  	case ir.PPARAMOUT:
  4803  		if s.hasdefer {
  4804  			// TODO: handle this case? Named return values must be
  4805  			// in memory so that the deferred function can see them.
  4806  			// Maybe do: if !strings.HasPrefix(n.String(), "~") { return false }
  4807  			// Or maybe not, see issue 18860.  Even unnamed return values
  4808  			// must be written back so if a defer recovers, the caller can see them.
  4809  			return false
  4810  		}
  4811  		if s.cgoUnsafeArgs {
  4812  			// Cgo effectively takes the address of all result args,
  4813  			// but the compiler can't see that.
  4814  			return false
  4815  		}
  4816  	}
  4817  	return true
  4818  	// TODO: try to make more variables SSAable?
  4819  }
  4820  
  4821  // exprPtr evaluates n to a pointer and nil-checks it.
  4822  func (s *state) exprPtr(n ir.Node, bounded bool, lineno src.XPos) *ssa.Value {
  4823  	p := s.expr(n)
  4824  	if bounded || n.NonNil() {
  4825  		if s.f.Frontend().Debug_checknil() && lineno.Line() > 1 {
  4826  			s.f.Warnl(lineno, "removed nil check")
  4827  		}
  4828  		return p
  4829  	}
  4830  	p = s.nilCheck(p)
  4831  	return p
  4832  }
  4833  
  4834  // nilCheck generates nil pointer checking code.
  4835  // Used only for automatically inserted nil checks,
  4836  // not for user code like 'x != nil'.
  4837  // Returns a "definitely not nil" copy of x to ensure proper ordering
  4838  // of the uses of the post-nilcheck pointer.
  4839  func (s *state) nilCheck(ptr *ssa.Value) *ssa.Value {
  4840  	if base.Debug.DisableNil != 0 || s.curfn.NilCheckDisabled() {
  4841  		return ptr
  4842  	}
  4843  	return s.newValue2(ssa.OpNilCheck, ptr.Type, ptr, s.mem())
  4844  }
  4845  
  4846  // boundsCheck generates bounds checking code. Checks if 0 <= idx <[=] len, branches to exit if not.
  4847  // Starts a new block on return.
  4848  // On input, len must be converted to full int width and be nonnegative.
  4849  // Returns idx converted to full int width.
  4850  // If bounded is true then caller guarantees the index is not out of bounds
  4851  // (but boundsCheck will still extend the index to full int width).
  4852  func (s *state) boundsCheck(idx, len *ssa.Value, kind ssa.BoundsKind, bounded bool) *ssa.Value {
  4853  	idx = s.extendIndex(idx, len, kind, bounded)
  4854  
  4855  	if bounded || base.Flag.B != 0 {
  4856  		// If bounded or bounds checking is flag-disabled, then no check necessary,
  4857  		// just return the extended index.
  4858  		//
  4859  		// Here, bounded == true if the compiler generated the index itself,
  4860  		// such as in the expansion of a slice initializer. These indexes are
  4861  		// compiler-generated, not Go program variables, so they cannot be
  4862  		// attacker-controlled, so we can omit Spectre masking as well.
  4863  		//
  4864  		// Note that we do not want to omit Spectre masking in code like:
  4865  		//
  4866  		//	if 0 <= i && i < len(x) {
  4867  		//		use(x[i])
  4868  		//	}
  4869  		//
  4870  		// Lucky for us, bounded==false for that code.
  4871  		// In that case (handled below), we emit a bound check (and Spectre mask)
  4872  		// and then the prove pass will remove the bounds check.
  4873  		// In theory the prove pass could potentially remove certain
  4874  		// Spectre masks, but it's very delicate and probably better
  4875  		// to be conservative and leave them all in.
  4876  		return idx
  4877  	}
  4878  
  4879  	bNext := s.f.NewBlock(ssa.BlockPlain)
  4880  	bPanic := s.f.NewBlock(ssa.BlockExit)
  4881  
  4882  	if !idx.Type.IsSigned() {
  4883  		switch kind {
  4884  		case ssa.BoundsIndex:
  4885  			kind = ssa.BoundsIndexU
  4886  		case ssa.BoundsSliceAlen:
  4887  			kind = ssa.BoundsSliceAlenU
  4888  		case ssa.BoundsSliceAcap:
  4889  			kind = ssa.BoundsSliceAcapU
  4890  		case ssa.BoundsSliceB:
  4891  			kind = ssa.BoundsSliceBU
  4892  		case ssa.BoundsSlice3Alen:
  4893  			kind = ssa.BoundsSlice3AlenU
  4894  		case ssa.BoundsSlice3Acap:
  4895  			kind = ssa.BoundsSlice3AcapU
  4896  		case ssa.BoundsSlice3B:
  4897  			kind = ssa.BoundsSlice3BU
  4898  		case ssa.BoundsSlice3C:
  4899  			kind = ssa.BoundsSlice3CU
  4900  		}
  4901  	}
  4902  
  4903  	var cmp *ssa.Value
  4904  	if kind == ssa.BoundsIndex || kind == ssa.BoundsIndexU {
  4905  		cmp = s.newValue2(ssa.OpIsInBounds, types.Types[types.TBOOL], idx, len)
  4906  	} else {
  4907  		cmp = s.newValue2(ssa.OpIsSliceInBounds, types.Types[types.TBOOL], idx, len)
  4908  	}
  4909  	b := s.endBlock()
  4910  	b.Kind = ssa.BlockIf
  4911  	b.SetControl(cmp)
  4912  	b.Likely = ssa.BranchLikely
  4913  	b.AddEdgeTo(bNext)
  4914  	b.AddEdgeTo(bPanic)
  4915  
  4916  	s.startBlock(bPanic)
  4917  	if Arch.LinkArch.Family == sys.Wasm {
  4918  		// TODO(khr): figure out how to do "register" based calling convention for bounds checks.
  4919  		// Should be similar to gcWriteBarrier, but I can't make it work.
  4920  		s.rtcall(BoundsCheckFunc[kind], false, nil, idx, len)
  4921  	} else {
  4922  		mem := s.newValue3I(ssa.OpPanicBounds, types.TypeMem, int64(kind), idx, len, s.mem())
  4923  		s.endBlock().SetControl(mem)
  4924  	}
  4925  	s.startBlock(bNext)
  4926  
  4927  	// In Spectre index mode, apply an appropriate mask to avoid speculative out-of-bounds accesses.
  4928  	if base.Flag.Cfg.SpectreIndex {
  4929  		op := ssa.OpSpectreIndex
  4930  		if kind != ssa.BoundsIndex && kind != ssa.BoundsIndexU {
  4931  			op = ssa.OpSpectreSliceIndex
  4932  		}
  4933  		idx = s.newValue2(op, types.Types[types.TINT], idx, len)
  4934  	}
  4935  
  4936  	return idx
  4937  }
  4938  
  4939  // If cmp (a bool) is false, panic using the given function.
  4940  func (s *state) check(cmp *ssa.Value, fn *obj.LSym) {
  4941  	b := s.endBlock()
  4942  	b.Kind = ssa.BlockIf
  4943  	b.SetControl(cmp)
  4944  	b.Likely = ssa.BranchLikely
  4945  	bNext := s.f.NewBlock(ssa.BlockPlain)
  4946  	line := s.peekPos()
  4947  	pos := base.Ctxt.PosTable.Pos(line)
  4948  	fl := funcLine{f: fn, base: pos.Base(), line: pos.Line()}
  4949  	bPanic := s.panics[fl]
  4950  	if bPanic == nil {
  4951  		bPanic = s.f.NewBlock(ssa.BlockPlain)
  4952  		s.panics[fl] = bPanic
  4953  		s.startBlock(bPanic)
  4954  		// The panic call takes/returns memory to ensure that the right
  4955  		// memory state is observed if the panic happens.
  4956  		s.rtcall(fn, false, nil)
  4957  	}
  4958  	b.AddEdgeTo(bNext)
  4959  	b.AddEdgeTo(bPanic)
  4960  	s.startBlock(bNext)
  4961  }
  4962  
  4963  func (s *state) intDivide(n ir.Node, a, b *ssa.Value) *ssa.Value {
  4964  	needcheck := true
  4965  	switch b.Op {
  4966  	case ssa.OpConst8, ssa.OpConst16, ssa.OpConst32, ssa.OpConst64:
  4967  		if b.AuxInt != 0 {
  4968  			needcheck = false
  4969  		}
  4970  	}
  4971  	if needcheck {
  4972  		// do a size-appropriate check for zero
  4973  		cmp := s.newValue2(s.ssaOp(ir.ONE, n.Type()), types.Types[types.TBOOL], b, s.zeroVal(n.Type()))
  4974  		s.check(cmp, ir.Syms.Panicdivide)
  4975  	}
  4976  	return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
  4977  }
  4978  
  4979  // rtcall issues a call to the given runtime function fn with the listed args.
  4980  // Returns a slice of results of the given result types.
  4981  // The call is added to the end of the current block.
  4982  // If returns is false, the block is marked as an exit block.
  4983  func (s *state) rtcall(fn *obj.LSym, returns bool, results []*types.Type, args ...*ssa.Value) []*ssa.Value {
  4984  	s.prevCall = nil
  4985  	// Write args to the stack
  4986  	off := base.Ctxt.Arch.FixedFrameSize
  4987  	var callArgs []*ssa.Value
  4988  	var callArgTypes []*types.Type
  4989  
  4990  	for _, arg := range args {
  4991  		t := arg.Type
  4992  		off = types.RoundUp(off, t.Alignment())
  4993  		size := t.Size()
  4994  		callArgs = append(callArgs, arg)
  4995  		callArgTypes = append(callArgTypes, t)
  4996  		off += size
  4997  	}
  4998  	off = types.RoundUp(off, int64(types.RegSize))
  4999  
  5000  	// Issue call
  5001  	var call *ssa.Value
  5002  	aux := ssa.StaticAuxCall(fn, s.f.ABIDefault.ABIAnalyzeTypes(callArgTypes, results))
  5003  	callArgs = append(callArgs, s.mem())
  5004  	call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
  5005  	call.AddArgs(callArgs...)
  5006  	s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, int64(len(results)), call)
  5007  
  5008  	if !returns {
  5009  		// Finish block
  5010  		b := s.endBlock()
  5011  		b.Kind = ssa.BlockExit
  5012  		b.SetControl(call)
  5013  		call.AuxInt = off - base.Ctxt.Arch.FixedFrameSize
  5014  		if len(results) > 0 {
  5015  			s.Fatalf("panic call can't have results")
  5016  		}
  5017  		return nil
  5018  	}
  5019  
  5020  	// Load results
  5021  	res := make([]*ssa.Value, len(results))
  5022  	for i, t := range results {
  5023  		off = types.RoundUp(off, t.Alignment())
  5024  		res[i] = s.resultOfCall(call, int64(i), t)
  5025  		off += t.Size()
  5026  	}
  5027  	off = types.RoundUp(off, int64(types.PtrSize))
  5028  
  5029  	// Remember how much callee stack space we needed.
  5030  	call.AuxInt = off
  5031  
  5032  	return res
  5033  }
  5034  
  5035  // do *left = right for type t.
  5036  func (s *state) storeType(t *types.Type, left, right *ssa.Value, skip skipMask, leftIsStmt bool) {
  5037  	s.instrument(t, left, instrumentWrite)
  5038  
  5039  	if skip == 0 && (!t.HasPointers() || ssa.IsStackAddr(left)) {
  5040  		// Known to not have write barrier. Store the whole type.
  5041  		s.vars[memVar] = s.newValue3Apos(ssa.OpStore, types.TypeMem, t, left, right, s.mem(), leftIsStmt)
  5042  		return
  5043  	}
  5044  
  5045  	// store scalar fields first, so write barrier stores for
  5046  	// pointer fields can be grouped together, and scalar values
  5047  	// don't need to be live across the write barrier call.
  5048  	// TODO: if the writebarrier pass knows how to reorder stores,
  5049  	// we can do a single store here as long as skip==0.
  5050  	s.storeTypeScalars(t, left, right, skip)
  5051  	if skip&skipPtr == 0 && t.HasPointers() {
  5052  		s.storeTypePtrs(t, left, right)
  5053  	}
  5054  }
  5055  
  5056  // do *left = right for all scalar (non-pointer) parts of t.
  5057  func (s *state) storeTypeScalars(t *types.Type, left, right *ssa.Value, skip skipMask) {
  5058  	switch {
  5059  	case t.IsBoolean() || t.IsInteger() || t.IsFloat() || t.IsComplex():
  5060  		s.store(t, left, right)
  5061  	case t.IsPtrShaped():
  5062  		if t.IsPtr() && t.Elem().NotInHeap() {
  5063  			s.store(t, left, right) // see issue 42032
  5064  		}
  5065  		// otherwise, no scalar fields.
  5066  	case t.IsString():
  5067  		if skip&skipLen != 0 {
  5068  			return
  5069  		}
  5070  		len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], right)
  5071  		lenAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, s.config.PtrSize, left)
  5072  		s.store(types.Types[types.TINT], lenAddr, len)
  5073  	case t.IsSlice():
  5074  		if skip&skipLen == 0 {
  5075  			len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], right)
  5076  			lenAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, s.config.PtrSize, left)
  5077  			s.store(types.Types[types.TINT], lenAddr, len)
  5078  		}
  5079  		if skip&skipCap == 0 {
  5080  			cap := s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], right)
  5081  			capAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, 2*s.config.PtrSize, left)
  5082  			s.store(types.Types[types.TINT], capAddr, cap)
  5083  		}
  5084  	case t.IsInterface():
  5085  		// itab field doesn't need a write barrier (even though it is a pointer).
  5086  		itab := s.newValue1(ssa.OpITab, s.f.Config.Types.BytePtr, right)
  5087  		s.store(types.Types[types.TUINTPTR], left, itab)
  5088  	case t.IsStruct():
  5089  		n := t.NumFields()
  5090  		for i := 0; i < n; i++ {
  5091  			ft := t.FieldType(i)
  5092  			addr := s.newValue1I(ssa.OpOffPtr, ft.PtrTo(), t.FieldOff(i), left)
  5093  			val := s.newValue1I(ssa.OpStructSelect, ft, int64(i), right)
  5094  			s.storeTypeScalars(ft, addr, val, 0)
  5095  		}
  5096  	case t.IsArray() && t.NumElem() == 0:
  5097  		// nothing
  5098  	case t.IsArray() && t.NumElem() == 1:
  5099  		s.storeTypeScalars(t.Elem(), left, s.newValue1I(ssa.OpArraySelect, t.Elem(), 0, right), 0)
  5100  	default:
  5101  		s.Fatalf("bad write barrier type %v", t)
  5102  	}
  5103  }
  5104  
  5105  // do *left = right for all pointer parts of t.
  5106  func (s *state) storeTypePtrs(t *types.Type, left, right *ssa.Value) {
  5107  	switch {
  5108  	case t.IsPtrShaped():
  5109  		if t.IsPtr() && t.Elem().NotInHeap() {
  5110  			break // see issue 42032
  5111  		}
  5112  		s.store(t, left, right)
  5113  	case t.IsString():
  5114  		ptr := s.newValue1(ssa.OpStringPtr, s.f.Config.Types.BytePtr, right)
  5115  		s.store(s.f.Config.Types.BytePtr, left, ptr)
  5116  	case t.IsSlice():
  5117  		elType := types.NewPtr(t.Elem())
  5118  		ptr := s.newValue1(ssa.OpSlicePtr, elType, right)
  5119  		s.store(elType, left, ptr)
  5120  	case t.IsInterface():
  5121  		// itab field is treated as a scalar.
  5122  		idata := s.newValue1(ssa.OpIData, s.f.Config.Types.BytePtr, right)
  5123  		idataAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.BytePtrPtr, s.config.PtrSize, left)
  5124  		s.store(s.f.Config.Types.BytePtr, idataAddr, idata)
  5125  	case t.IsStruct():
  5126  		n := t.NumFields()
  5127  		for i := 0; i < n; i++ {
  5128  			ft := t.FieldType(i)
  5129  			if !ft.HasPointers() {
  5130  				continue
  5131  			}
  5132  			addr := s.newValue1I(ssa.OpOffPtr, ft.PtrTo(), t.FieldOff(i), left)
  5133  			val := s.newValue1I(ssa.OpStructSelect, ft, int64(i), right)
  5134  			s.storeTypePtrs(ft, addr, val)
  5135  		}
  5136  	case t.IsArray() && t.NumElem() == 0:
  5137  		// nothing
  5138  	case t.IsArray() && t.NumElem() == 1:
  5139  		s.storeTypePtrs(t.Elem(), left, s.newValue1I(ssa.OpArraySelect, t.Elem(), 0, right))
  5140  	default:
  5141  		s.Fatalf("bad write barrier type %v", t)
  5142  	}
  5143  }
  5144  
  5145  // putArg evaluates n for the purpose of passing it as an argument to a function and returns the value for the call.
  5146  func (s *state) putArg(n ir.Node, t *types.Type) *ssa.Value {
  5147  	var a *ssa.Value
  5148  	if !ssa.CanSSA(t) {
  5149  		a = s.newValue2(ssa.OpDereference, t, s.addr(n), s.mem())
  5150  	} else {
  5151  		a = s.expr(n)
  5152  	}
  5153  	return a
  5154  }
  5155  
  5156  func (s *state) storeArgWithBase(n ir.Node, t *types.Type, base *ssa.Value, off int64) {
  5157  	pt := types.NewPtr(t)
  5158  	var addr *ssa.Value
  5159  	if base == s.sp {
  5160  		// Use special routine that avoids allocation on duplicate offsets.
  5161  		addr = s.constOffPtrSP(pt, off)
  5162  	} else {
  5163  		addr = s.newValue1I(ssa.OpOffPtr, pt, off, base)
  5164  	}
  5165  
  5166  	if !ssa.CanSSA(t) {
  5167  		a := s.addr(n)
  5168  		s.move(t, addr, a)
  5169  		return
  5170  	}
  5171  
  5172  	a := s.expr(n)
  5173  	s.storeType(t, addr, a, 0, false)
  5174  }
  5175  
  5176  // slice computes the slice v[i:j:k] and returns ptr, len, and cap of result.
  5177  // i,j,k may be nil, in which case they are set to their default value.
  5178  // v may be a slice, string or pointer to an array.
  5179  func (s *state) slice(v, i, j, k *ssa.Value, bounded bool) (p, l, c *ssa.Value) {
  5180  	t := v.Type
  5181  	var ptr, len, cap *ssa.Value
  5182  	switch {
  5183  	case t.IsSlice():
  5184  		ptr = s.newValue1(ssa.OpSlicePtr, types.NewPtr(t.Elem()), v)
  5185  		len = s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], v)
  5186  		cap = s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], v)
  5187  	case t.IsString():
  5188  		ptr = s.newValue1(ssa.OpStringPtr, types.NewPtr(types.Types[types.TUINT8]), v)
  5189  		len = s.newValue1(ssa.OpStringLen, types.Types[types.TINT], v)
  5190  		cap = len
  5191  	case t.IsPtr():
  5192  		if !t.Elem().IsArray() {
  5193  			s.Fatalf("bad ptr to array in slice %v\n", t)
  5194  		}
  5195  		nv := s.nilCheck(v)
  5196  		ptr = s.newValue1(ssa.OpCopy, types.NewPtr(t.Elem().Elem()), nv)
  5197  		len = s.constInt(types.Types[types.TINT], t.Elem().NumElem())
  5198  		cap = len
  5199  	default:
  5200  		s.Fatalf("bad type in slice %v\n", t)
  5201  	}
  5202  
  5203  	// Set default values
  5204  	if i == nil {
  5205  		i = s.constInt(types.Types[types.TINT], 0)
  5206  	}
  5207  	if j == nil {
  5208  		j = len
  5209  	}
  5210  	three := true
  5211  	if k == nil {
  5212  		three = false
  5213  		k = cap
  5214  	}
  5215  
  5216  	// Panic if slice indices are not in bounds.
  5217  	// Make sure we check these in reverse order so that we're always
  5218  	// comparing against a value known to be nonnegative. See issue 28797.
  5219  	if three {
  5220  		if k != cap {
  5221  			kind := ssa.BoundsSlice3Alen
  5222  			if t.IsSlice() {
  5223  				kind = ssa.BoundsSlice3Acap
  5224  			}
  5225  			k = s.boundsCheck(k, cap, kind, bounded)
  5226  		}
  5227  		if j != k {
  5228  			j = s.boundsCheck(j, k, ssa.BoundsSlice3B, bounded)
  5229  		}
  5230  		i = s.boundsCheck(i, j, ssa.BoundsSlice3C, bounded)
  5231  	} else {
  5232  		if j != k {
  5233  			kind := ssa.BoundsSliceAlen
  5234  			if t.IsSlice() {
  5235  				kind = ssa.BoundsSliceAcap
  5236  			}
  5237  			j = s.boundsCheck(j, k, kind, bounded)
  5238  		}
  5239  		i = s.boundsCheck(i, j, ssa.BoundsSliceB, bounded)
  5240  	}
  5241  
  5242  	// Word-sized integer operations.
  5243  	subOp := s.ssaOp(ir.OSUB, types.Types[types.TINT])
  5244  	mulOp := s.ssaOp(ir.OMUL, types.Types[types.TINT])
  5245  	andOp := s.ssaOp(ir.OAND, types.Types[types.TINT])
  5246  
  5247  	// Calculate the length (rlen) and capacity (rcap) of the new slice.
  5248  	// For strings the capacity of the result is unimportant. However,
  5249  	// we use rcap to test if we've generated a zero-length slice.
  5250  	// Use length of strings for that.
  5251  	rlen := s.newValue2(subOp, types.Types[types.TINT], j, i)
  5252  	rcap := rlen
  5253  	if j != k && !t.IsString() {
  5254  		rcap = s.newValue2(subOp, types.Types[types.TINT], k, i)
  5255  	}
  5256  
  5257  	if (i.Op == ssa.OpConst64 || i.Op == ssa.OpConst32) && i.AuxInt == 0 {
  5258  		// No pointer arithmetic necessary.
  5259  		return ptr, rlen, rcap
  5260  	}
  5261  
  5262  	// Calculate the base pointer (rptr) for the new slice.
  5263  	//
  5264  	// Generate the following code assuming that indexes are in bounds.
  5265  	// The masking is to make sure that we don't generate a slice
  5266  	// that points to the next object in memory. We cannot just set
  5267  	// the pointer to nil because then we would create a nil slice or
  5268  	// string.
  5269  	//
  5270  	//     rcap = k - i
  5271  	//     rlen = j - i
  5272  	//     rptr = ptr + (mask(rcap) & (i * stride))
  5273  	//
  5274  	// Where mask(x) is 0 if x==0 and -1 if x>0 and stride is the width
  5275  	// of the element type.
  5276  	stride := s.constInt(types.Types[types.TINT], ptr.Type.Elem().Size())
  5277  
  5278  	// The delta is the number of bytes to offset ptr by.
  5279  	delta := s.newValue2(mulOp, types.Types[types.TINT], i, stride)
  5280  
  5281  	// If we're slicing to the point where the capacity is zero,
  5282  	// zero out the delta.
  5283  	mask := s.newValue1(ssa.OpSlicemask, types.Types[types.TINT], rcap)
  5284  	delta = s.newValue2(andOp, types.Types[types.TINT], delta, mask)
  5285  
  5286  	// Compute rptr = ptr + delta.
  5287  	rptr := s.newValue2(ssa.OpAddPtr, ptr.Type, ptr, delta)
  5288  
  5289  	return rptr, rlen, rcap
  5290  }
  5291  
  5292  type u642fcvtTab struct {
  5293  	leq, cvt2F, and, rsh, or, add ssa.Op
  5294  	one                           func(*state, *types.Type, int64) *ssa.Value
  5295  }
  5296  
  5297  var u64_f64 = u642fcvtTab{
  5298  	leq:   ssa.OpLeq64,
  5299  	cvt2F: ssa.OpCvt64to64F,
  5300  	and:   ssa.OpAnd64,
  5301  	rsh:   ssa.OpRsh64Ux64,
  5302  	or:    ssa.OpOr64,
  5303  	add:   ssa.OpAdd64F,
  5304  	one:   (*state).constInt64,
  5305  }
  5306  
  5307  var u64_f32 = u642fcvtTab{
  5308  	leq:   ssa.OpLeq64,
  5309  	cvt2F: ssa.OpCvt64to32F,
  5310  	and:   ssa.OpAnd64,
  5311  	rsh:   ssa.OpRsh64Ux64,
  5312  	or:    ssa.OpOr64,
  5313  	add:   ssa.OpAdd32F,
  5314  	one:   (*state).constInt64,
  5315  }
  5316  
  5317  func (s *state) uint64Tofloat64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5318  	return s.uint64Tofloat(&u64_f64, n, x, ft, tt)
  5319  }
  5320  
  5321  func (s *state) uint64Tofloat32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5322  	return s.uint64Tofloat(&u64_f32, n, x, ft, tt)
  5323  }
  5324  
  5325  func (s *state) uint64Tofloat(cvttab *u642fcvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5326  	// if x >= 0 {
  5327  	//    result = (floatY) x
  5328  	// } else {
  5329  	// 	  y = uintX(x) ; y = x & 1
  5330  	// 	  z = uintX(x) ; z = z >> 1
  5331  	// 	  z = z | y
  5332  	// 	  result = floatY(z)
  5333  	// 	  result = result + result
  5334  	// }
  5335  	//
  5336  	// Code borrowed from old code generator.
  5337  	// What's going on: large 64-bit "unsigned" looks like
  5338  	// negative number to hardware's integer-to-float
  5339  	// conversion. However, because the mantissa is only
  5340  	// 63 bits, we don't need the LSB, so instead we do an
  5341  	// unsigned right shift (divide by two), convert, and
  5342  	// double. However, before we do that, we need to be
  5343  	// sure that we do not lose a "1" if that made the
  5344  	// difference in the resulting rounding. Therefore, we
  5345  	// preserve it, and OR (not ADD) it back in. The case
  5346  	// that matters is when the eleven discarded bits are
  5347  	// equal to 10000000001; that rounds up, and the 1 cannot
  5348  	// be lost else it would round down if the LSB of the
  5349  	// candidate mantissa is 0.
  5350  	cmp := s.newValue2(cvttab.leq, types.Types[types.TBOOL], s.zeroVal(ft), x)
  5351  	b := s.endBlock()
  5352  	b.Kind = ssa.BlockIf
  5353  	b.SetControl(cmp)
  5354  	b.Likely = ssa.BranchLikely
  5355  
  5356  	bThen := s.f.NewBlock(ssa.BlockPlain)
  5357  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5358  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5359  
  5360  	b.AddEdgeTo(bThen)
  5361  	s.startBlock(bThen)
  5362  	a0 := s.newValue1(cvttab.cvt2F, tt, x)
  5363  	s.vars[n] = a0
  5364  	s.endBlock()
  5365  	bThen.AddEdgeTo(bAfter)
  5366  
  5367  	b.AddEdgeTo(bElse)
  5368  	s.startBlock(bElse)
  5369  	one := cvttab.one(s, ft, 1)
  5370  	y := s.newValue2(cvttab.and, ft, x, one)
  5371  	z := s.newValue2(cvttab.rsh, ft, x, one)
  5372  	z = s.newValue2(cvttab.or, ft, z, y)
  5373  	a := s.newValue1(cvttab.cvt2F, tt, z)
  5374  	a1 := s.newValue2(cvttab.add, tt, a, a)
  5375  	s.vars[n] = a1
  5376  	s.endBlock()
  5377  	bElse.AddEdgeTo(bAfter)
  5378  
  5379  	s.startBlock(bAfter)
  5380  	return s.variable(n, n.Type())
  5381  }
  5382  
  5383  type u322fcvtTab struct {
  5384  	cvtI2F, cvtF2F ssa.Op
  5385  }
  5386  
  5387  var u32_f64 = u322fcvtTab{
  5388  	cvtI2F: ssa.OpCvt32to64F,
  5389  	cvtF2F: ssa.OpCopy,
  5390  }
  5391  
  5392  var u32_f32 = u322fcvtTab{
  5393  	cvtI2F: ssa.OpCvt32to32F,
  5394  	cvtF2F: ssa.OpCvt64Fto32F,
  5395  }
  5396  
  5397  func (s *state) uint32Tofloat64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5398  	return s.uint32Tofloat(&u32_f64, n, x, ft, tt)
  5399  }
  5400  
  5401  func (s *state) uint32Tofloat32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5402  	return s.uint32Tofloat(&u32_f32, n, x, ft, tt)
  5403  }
  5404  
  5405  func (s *state) uint32Tofloat(cvttab *u322fcvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5406  	// if x >= 0 {
  5407  	// 	result = floatY(x)
  5408  	// } else {
  5409  	// 	result = floatY(float64(x) + (1<<32))
  5410  	// }
  5411  	cmp := s.newValue2(ssa.OpLeq32, types.Types[types.TBOOL], s.zeroVal(ft), x)
  5412  	b := s.endBlock()
  5413  	b.Kind = ssa.BlockIf
  5414  	b.SetControl(cmp)
  5415  	b.Likely = ssa.BranchLikely
  5416  
  5417  	bThen := s.f.NewBlock(ssa.BlockPlain)
  5418  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5419  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5420  
  5421  	b.AddEdgeTo(bThen)
  5422  	s.startBlock(bThen)
  5423  	a0 := s.newValue1(cvttab.cvtI2F, tt, x)
  5424  	s.vars[n] = a0
  5425  	s.endBlock()
  5426  	bThen.AddEdgeTo(bAfter)
  5427  
  5428  	b.AddEdgeTo(bElse)
  5429  	s.startBlock(bElse)
  5430  	a1 := s.newValue1(ssa.OpCvt32to64F, types.Types[types.TFLOAT64], x)
  5431  	twoToThe32 := s.constFloat64(types.Types[types.TFLOAT64], float64(1<<32))
  5432  	a2 := s.newValue2(ssa.OpAdd64F, types.Types[types.TFLOAT64], a1, twoToThe32)
  5433  	a3 := s.newValue1(cvttab.cvtF2F, tt, a2)
  5434  
  5435  	s.vars[n] = a3
  5436  	s.endBlock()
  5437  	bElse.AddEdgeTo(bAfter)
  5438  
  5439  	s.startBlock(bAfter)
  5440  	return s.variable(n, n.Type())
  5441  }
  5442  
  5443  // referenceTypeBuiltin generates code for the len/cap builtins for maps and channels.
  5444  func (s *state) referenceTypeBuiltin(n *ir.UnaryExpr, x *ssa.Value) *ssa.Value {
  5445  	if !n.X.Type().IsMap() && !n.X.Type().IsChan() {
  5446  		s.Fatalf("node must be a map or a channel")
  5447  	}
  5448  	if n.X.Type().IsChan() && n.Op() == ir.OLEN {
  5449  		s.Fatalf("cannot inline len(chan)") // must use runtime.chanlen now
  5450  	}
  5451  	if n.X.Type().IsChan() && n.Op() == ir.OCAP {
  5452  		s.Fatalf("cannot inline cap(chan)") // must use runtime.chancap now
  5453  	}
  5454  	// if n == nil {
  5455  	//   return 0
  5456  	// } else {
  5457  	//   // len
  5458  	//   return *((*int)n)
  5459  	//   // cap
  5460  	//   return *(((*int)n)+1)
  5461  	// }
  5462  	lenType := n.Type()
  5463  	nilValue := s.constNil(types.Types[types.TUINTPTR])
  5464  	cmp := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], x, nilValue)
  5465  	b := s.endBlock()
  5466  	b.Kind = ssa.BlockIf
  5467  	b.SetControl(cmp)
  5468  	b.Likely = ssa.BranchUnlikely
  5469  
  5470  	bThen := s.f.NewBlock(ssa.BlockPlain)
  5471  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5472  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5473  
  5474  	// length/capacity of a nil map/chan is zero
  5475  	b.AddEdgeTo(bThen)
  5476  	s.startBlock(bThen)
  5477  	s.vars[n] = s.zeroVal(lenType)
  5478  	s.endBlock()
  5479  	bThen.AddEdgeTo(bAfter)
  5480  
  5481  	b.AddEdgeTo(bElse)
  5482  	s.startBlock(bElse)
  5483  	switch n.Op() {
  5484  	case ir.OLEN:
  5485  		if buildcfg.Experiment.SwissMap && n.X.Type().IsMap() {
  5486  			// length is stored in the first word.
  5487  			s.vars[n] = s.load(lenType, x)
  5488  		} else {
  5489  			// length is stored in the first word for map/chan
  5490  			s.vars[n] = s.load(lenType, x)
  5491  		}
  5492  	case ir.OCAP:
  5493  		// capacity is stored in the second word for chan
  5494  		sw := s.newValue1I(ssa.OpOffPtr, lenType.PtrTo(), lenType.Size(), x)
  5495  		s.vars[n] = s.load(lenType, sw)
  5496  	default:
  5497  		s.Fatalf("op must be OLEN or OCAP")
  5498  	}
  5499  	s.endBlock()
  5500  	bElse.AddEdgeTo(bAfter)
  5501  
  5502  	s.startBlock(bAfter)
  5503  	return s.variable(n, lenType)
  5504  }
  5505  
  5506  type f2uCvtTab struct {
  5507  	ltf, cvt2U, subf, or ssa.Op
  5508  	floatValue           func(*state, *types.Type, float64) *ssa.Value
  5509  	intValue             func(*state, *types.Type, int64) *ssa.Value
  5510  	cutoff               uint64
  5511  }
  5512  
  5513  var f32_u64 = f2uCvtTab{
  5514  	ltf:        ssa.OpLess32F,
  5515  	cvt2U:      ssa.OpCvt32Fto64,
  5516  	subf:       ssa.OpSub32F,
  5517  	or:         ssa.OpOr64,
  5518  	floatValue: (*state).constFloat32,
  5519  	intValue:   (*state).constInt64,
  5520  	cutoff:     1 << 63,
  5521  }
  5522  
  5523  var f64_u64 = f2uCvtTab{
  5524  	ltf:        ssa.OpLess64F,
  5525  	cvt2U:      ssa.OpCvt64Fto64,
  5526  	subf:       ssa.OpSub64F,
  5527  	or:         ssa.OpOr64,
  5528  	floatValue: (*state).constFloat64,
  5529  	intValue:   (*state).constInt64,
  5530  	cutoff:     1 << 63,
  5531  }
  5532  
  5533  var f32_u32 = f2uCvtTab{
  5534  	ltf:        ssa.OpLess32F,
  5535  	cvt2U:      ssa.OpCvt32Fto32,
  5536  	subf:       ssa.OpSub32F,
  5537  	or:         ssa.OpOr32,
  5538  	floatValue: (*state).constFloat32,
  5539  	intValue:   func(s *state, t *types.Type, v int64) *ssa.Value { return s.constInt32(t, int32(v)) },
  5540  	cutoff:     1 << 31,
  5541  }
  5542  
  5543  var f64_u32 = f2uCvtTab{
  5544  	ltf:        ssa.OpLess64F,
  5545  	cvt2U:      ssa.OpCvt64Fto32,
  5546  	subf:       ssa.OpSub64F,
  5547  	or:         ssa.OpOr32,
  5548  	floatValue: (*state).constFloat64,
  5549  	intValue:   func(s *state, t *types.Type, v int64) *ssa.Value { return s.constInt32(t, int32(v)) },
  5550  	cutoff:     1 << 31,
  5551  }
  5552  
  5553  func (s *state) float32ToUint64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5554  	return s.floatToUint(&f32_u64, n, x, ft, tt)
  5555  }
  5556  func (s *state) float64ToUint64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5557  	return s.floatToUint(&f64_u64, n, x, ft, tt)
  5558  }
  5559  
  5560  func (s *state) float32ToUint32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5561  	return s.floatToUint(&f32_u32, n, x, ft, tt)
  5562  }
  5563  
  5564  func (s *state) float64ToUint32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5565  	return s.floatToUint(&f64_u32, n, x, ft, tt)
  5566  }
  5567  
  5568  func (s *state) floatToUint(cvttab *f2uCvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
  5569  	// cutoff:=1<<(intY_Size-1)
  5570  	// if x < floatX(cutoff) {
  5571  	// 	result = uintY(x)
  5572  	// } else {
  5573  	// 	y = x - floatX(cutoff)
  5574  	// 	z = uintY(y)
  5575  	// 	result = z | -(cutoff)
  5576  	// }
  5577  	cutoff := cvttab.floatValue(s, ft, float64(cvttab.cutoff))
  5578  	cmp := s.newValue2(cvttab.ltf, types.Types[types.TBOOL], x, cutoff)
  5579  	b := s.endBlock()
  5580  	b.Kind = ssa.BlockIf
  5581  	b.SetControl(cmp)
  5582  	b.Likely = ssa.BranchLikely
  5583  
  5584  	bThen := s.f.NewBlock(ssa.BlockPlain)
  5585  	bElse := s.f.NewBlock(ssa.BlockPlain)
  5586  	bAfter := s.f.NewBlock(ssa.BlockPlain)
  5587  
  5588  	b.AddEdgeTo(bThen)
  5589  	s.startBlock(bThen)
  5590  	a0 := s.newValue1(cvttab.cvt2U, tt, x)
  5591  	s.vars[n] = a0
  5592  	s.endBlock()
  5593  	bThen.AddEdgeTo(bAfter)
  5594  
  5595  	b.AddEdgeTo(bElse)
  5596  	s.startBlock(bElse)
  5597  	y := s.newValue2(cvttab.subf, ft, x, cutoff)
  5598  	y = s.newValue1(cvttab.cvt2U, tt, y)
  5599  	z := cvttab.intValue(s, tt, int64(-cvttab.cutoff))
  5600  	a1 := s.newValue2(cvttab.or, tt, y, z)
  5601  	s.vars[n] = a1
  5602  	s.endBlock()
  5603  	bElse.AddEdgeTo(bAfter)
  5604  
  5605  	s.startBlock(bAfter)
  5606  	return s.variable(n, n.Type())
  5607  }
  5608  
  5609  // dottype generates SSA for a type assertion node.
  5610  // commaok indicates whether to panic or return a bool.
  5611  // If commaok is false, resok will be nil.
  5612  func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
  5613  	iface := s.expr(n.X)              // input interface
  5614  	target := s.reflectType(n.Type()) // target type
  5615  	var targetItab *ssa.Value
  5616  	if n.ITab != nil {
  5617  		targetItab = s.expr(n.ITab)
  5618  	}
  5619  	return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, nil, target, targetItab, commaok, n.Descriptor)
  5620  }
  5621  
  5622  func (s *state) dynamicDottype(n *ir.DynamicTypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
  5623  	iface := s.expr(n.X)
  5624  	var source, target, targetItab *ssa.Value
  5625  	if n.SrcRType != nil {
  5626  		source = s.expr(n.SrcRType)
  5627  	}
  5628  	if !n.X.Type().IsEmptyInterface() && !n.Type().IsInterface() {
  5629  		byteptr := s.f.Config.Types.BytePtr
  5630  		targetItab = s.expr(n.ITab)
  5631  		// TODO(mdempsky): Investigate whether compiling n.RType could be
  5632  		// better than loading itab.typ.
  5633  		target = s.load(byteptr, s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), targetItab))
  5634  	} else {
  5635  		target = s.expr(n.RType)
  5636  	}
  5637  	return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, source, target, targetItab, commaok, nil)
  5638  }
  5639  
  5640  // dottype1 implements a x.(T) operation. iface is the argument (x), dst is the type we're asserting to (T)
  5641  // and src is the type we're asserting from.
  5642  // source is the *runtime._type of src
  5643  // target is the *runtime._type of dst.
  5644  // If src is a nonempty interface and dst is not an interface, targetItab is an itab representing (dst, src). Otherwise it is nil.
  5645  // commaok is true if the caller wants a boolean success value. Otherwise, the generated code panics if the conversion fails.
  5646  // descriptor is a compiler-allocated internal/abi.TypeAssert whose address is passed to runtime.typeAssert when
  5647  // the target type is a compile-time-known non-empty interface. It may be nil.
  5648  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) {
  5649  	typs := s.f.Config.Types
  5650  	byteptr := typs.BytePtr
  5651  	if dst.IsInterface() {
  5652  		if dst.IsEmptyInterface() {
  5653  			// Converting to an empty interface.
  5654  			// Input could be an empty or nonempty interface.
  5655  			if base.Debug.TypeAssert > 0 {
  5656  				base.WarnfAt(pos, "type assertion inlined")
  5657  			}
  5658  
  5659  			// Get itab/type field from input.
  5660  			itab := s.newValue1(ssa.OpITab, byteptr, iface)
  5661  			// Conversion succeeds iff that field is not nil.
  5662  			cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  5663  
  5664  			if src.IsEmptyInterface() && commaok {
  5665  				// Converting empty interface to empty interface with ,ok is just a nil check.
  5666  				return iface, cond
  5667  			}
  5668  
  5669  			// Branch on nilness.
  5670  			b := s.endBlock()
  5671  			b.Kind = ssa.BlockIf
  5672  			b.SetControl(cond)
  5673  			b.Likely = ssa.BranchLikely
  5674  			bOk := s.f.NewBlock(ssa.BlockPlain)
  5675  			bFail := s.f.NewBlock(ssa.BlockPlain)
  5676  			b.AddEdgeTo(bOk)
  5677  			b.AddEdgeTo(bFail)
  5678  
  5679  			if !commaok {
  5680  				// On failure, panic by calling panicnildottype.
  5681  				s.startBlock(bFail)
  5682  				s.rtcall(ir.Syms.Panicnildottype, false, nil, target)
  5683  
  5684  				// On success, return (perhaps modified) input interface.
  5685  				s.startBlock(bOk)
  5686  				if src.IsEmptyInterface() {
  5687  					res = iface // Use input interface unchanged.
  5688  					return
  5689  				}
  5690  				// Load type out of itab, build interface with existing idata.
  5691  				off := s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab)
  5692  				typ := s.load(byteptr, off)
  5693  				idata := s.newValue1(ssa.OpIData, byteptr, iface)
  5694  				res = s.newValue2(ssa.OpIMake, dst, typ, idata)
  5695  				return
  5696  			}
  5697  
  5698  			s.startBlock(bOk)
  5699  			// nonempty -> empty
  5700  			// Need to load type from itab
  5701  			off := s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab)
  5702  			s.vars[typVar] = s.load(byteptr, off)
  5703  			s.endBlock()
  5704  
  5705  			// itab is nil, might as well use that as the nil result.
  5706  			s.startBlock(bFail)
  5707  			s.vars[typVar] = itab
  5708  			s.endBlock()
  5709  
  5710  			// Merge point.
  5711  			bEnd := s.f.NewBlock(ssa.BlockPlain)
  5712  			bOk.AddEdgeTo(bEnd)
  5713  			bFail.AddEdgeTo(bEnd)
  5714  			s.startBlock(bEnd)
  5715  			idata := s.newValue1(ssa.OpIData, byteptr, iface)
  5716  			res = s.newValue2(ssa.OpIMake, dst, s.variable(typVar, byteptr), idata)
  5717  			resok = cond
  5718  			delete(s.vars, typVar) // no practical effect, just to indicate typVar is no longer live.
  5719  			return
  5720  		}
  5721  		// converting to a nonempty interface needs a runtime call.
  5722  		if base.Debug.TypeAssert > 0 {
  5723  			base.WarnfAt(pos, "type assertion not inlined")
  5724  		}
  5725  
  5726  		itab := s.newValue1(ssa.OpITab, byteptr, iface)
  5727  		data := s.newValue1(ssa.OpIData, types.Types[types.TUNSAFEPTR], iface)
  5728  
  5729  		// First, check for nil.
  5730  		bNil := s.f.NewBlock(ssa.BlockPlain)
  5731  		bNonNil := s.f.NewBlock(ssa.BlockPlain)
  5732  		bMerge := s.f.NewBlock(ssa.BlockPlain)
  5733  		cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  5734  		b := s.endBlock()
  5735  		b.Kind = ssa.BlockIf
  5736  		b.SetControl(cond)
  5737  		b.Likely = ssa.BranchLikely
  5738  		b.AddEdgeTo(bNonNil)
  5739  		b.AddEdgeTo(bNil)
  5740  
  5741  		s.startBlock(bNil)
  5742  		if commaok {
  5743  			s.vars[typVar] = itab // which will be nil
  5744  			b := s.endBlock()
  5745  			b.AddEdgeTo(bMerge)
  5746  		} else {
  5747  			// Panic if input is nil.
  5748  			s.rtcall(ir.Syms.Panicnildottype, false, nil, target)
  5749  		}
  5750  
  5751  		// Get typ, possibly by loading out of itab.
  5752  		s.startBlock(bNonNil)
  5753  		typ := itab
  5754  		if !src.IsEmptyInterface() {
  5755  			typ = s.load(byteptr, s.newValue1I(ssa.OpOffPtr, byteptr, rttype.ITab.OffsetOf("Type"), itab))
  5756  		}
  5757  
  5758  		// Check the cache first.
  5759  		var d *ssa.Value
  5760  		if descriptor != nil {
  5761  			d = s.newValue1A(ssa.OpAddr, byteptr, descriptor, s.sb)
  5762  			if base.Flag.N == 0 && rtabi.UseInterfaceSwitchCache(Arch.LinkArch.Name) {
  5763  				// Note: we can only use the cache if we have the right atomic load instruction.
  5764  				// Double-check that here.
  5765  				if intrinsics.lookup(Arch.LinkArch.Arch, "internal/runtime/atomic", "Loadp") == nil {
  5766  					s.Fatalf("atomic load not available")
  5767  				}
  5768  				// Pick right size ops.
  5769  				var mul, and, add, zext ssa.Op
  5770  				if s.config.PtrSize == 4 {
  5771  					mul = ssa.OpMul32
  5772  					and = ssa.OpAnd32
  5773  					add = ssa.OpAdd32
  5774  					zext = ssa.OpCopy
  5775  				} else {
  5776  					mul = ssa.OpMul64
  5777  					and = ssa.OpAnd64
  5778  					add = ssa.OpAdd64
  5779  					zext = ssa.OpZeroExt32to64
  5780  				}
  5781  
  5782  				loopHead := s.f.NewBlock(ssa.BlockPlain)
  5783  				loopBody := s.f.NewBlock(ssa.BlockPlain)
  5784  				cacheHit := s.f.NewBlock(ssa.BlockPlain)
  5785  				cacheMiss := s.f.NewBlock(ssa.BlockPlain)
  5786  
  5787  				// Load cache pointer out of descriptor, with an atomic load so
  5788  				// we ensure that we see a fully written cache.
  5789  				atomicLoad := s.newValue2(ssa.OpAtomicLoadPtr, types.NewTuple(typs.BytePtr, types.TypeMem), d, s.mem())
  5790  				cache := s.newValue1(ssa.OpSelect0, typs.BytePtr, atomicLoad)
  5791  				s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, atomicLoad)
  5792  
  5793  				// Load hash from type or itab.
  5794  				var hash *ssa.Value
  5795  				if src.IsEmptyInterface() {
  5796  					hash = s.newValue2(ssa.OpLoad, typs.UInt32, s.newValue1I(ssa.OpOffPtr, typs.UInt32Ptr, rttype.Type.OffsetOf("Hash"), typ), s.mem())
  5797  				} else {
  5798  					hash = s.newValue2(ssa.OpLoad, typs.UInt32, s.newValue1I(ssa.OpOffPtr, typs.UInt32Ptr, rttype.ITab.OffsetOf("Hash"), itab), s.mem())
  5799  				}
  5800  				hash = s.newValue1(zext, typs.Uintptr, hash)
  5801  				s.vars[hashVar] = hash
  5802  				// Load mask from cache.
  5803  				mask := s.newValue2(ssa.OpLoad, typs.Uintptr, cache, s.mem())
  5804  				// Jump to loop head.
  5805  				b := s.endBlock()
  5806  				b.AddEdgeTo(loopHead)
  5807  
  5808  				// At loop head, get pointer to the cache entry.
  5809  				//   e := &cache.Entries[hash&mask]
  5810  				s.startBlock(loopHead)
  5811  				idx := s.newValue2(and, typs.Uintptr, s.variable(hashVar, typs.Uintptr), mask)
  5812  				idx = s.newValue2(mul, typs.Uintptr, idx, s.uintptrConstant(uint64(2*s.config.PtrSize)))
  5813  				idx = s.newValue2(add, typs.Uintptr, idx, s.uintptrConstant(uint64(s.config.PtrSize)))
  5814  				e := s.newValue2(ssa.OpAddPtr, typs.UintptrPtr, cache, idx)
  5815  				//   hash++
  5816  				s.vars[hashVar] = s.newValue2(add, typs.Uintptr, s.variable(hashVar, typs.Uintptr), s.uintptrConstant(1))
  5817  
  5818  				// Look for a cache hit.
  5819  				//   if e.Typ == typ { goto hit }
  5820  				eTyp := s.newValue2(ssa.OpLoad, typs.Uintptr, e, s.mem())
  5821  				cmp1 := s.newValue2(ssa.OpEqPtr, typs.Bool, typ, eTyp)
  5822  				b = s.endBlock()
  5823  				b.Kind = ssa.BlockIf
  5824  				b.SetControl(cmp1)
  5825  				b.AddEdgeTo(cacheHit)
  5826  				b.AddEdgeTo(loopBody)
  5827  
  5828  				// Look for an empty entry, the tombstone for this hash table.
  5829  				//   if e.Typ == nil { goto miss }
  5830  				s.startBlock(loopBody)
  5831  				cmp2 := s.newValue2(ssa.OpEqPtr, typs.Bool, eTyp, s.constNil(typs.BytePtr))
  5832  				b = s.endBlock()
  5833  				b.Kind = ssa.BlockIf
  5834  				b.SetControl(cmp2)
  5835  				b.AddEdgeTo(cacheMiss)
  5836  				b.AddEdgeTo(loopHead)
  5837  
  5838  				// On a hit, load the data fields of the cache entry.
  5839  				//   Itab = e.Itab
  5840  				s.startBlock(cacheHit)
  5841  				eItab := s.newValue2(ssa.OpLoad, typs.BytePtr, s.newValue1I(ssa.OpOffPtr, typs.BytePtrPtr, s.config.PtrSize, e), s.mem())
  5842  				s.vars[typVar] = eItab
  5843  				b = s.endBlock()
  5844  				b.AddEdgeTo(bMerge)
  5845  
  5846  				// On a miss, call into the runtime to get the answer.
  5847  				s.startBlock(cacheMiss)
  5848  			}
  5849  		}
  5850  
  5851  		// Call into runtime to get itab for result.
  5852  		if descriptor != nil {
  5853  			itab = s.rtcall(ir.Syms.TypeAssert, true, []*types.Type{byteptr}, d, typ)[0]
  5854  		} else {
  5855  			var fn *obj.LSym
  5856  			if commaok {
  5857  				fn = ir.Syms.AssertE2I2
  5858  			} else {
  5859  				fn = ir.Syms.AssertE2I
  5860  			}
  5861  			itab = s.rtcall(fn, true, []*types.Type{byteptr}, target, typ)[0]
  5862  		}
  5863  		s.vars[typVar] = itab
  5864  		b = s.endBlock()
  5865  		b.AddEdgeTo(bMerge)
  5866  
  5867  		// Build resulting interface.
  5868  		s.startBlock(bMerge)
  5869  		itab = s.variable(typVar, byteptr)
  5870  		var ok *ssa.Value
  5871  		if commaok {
  5872  			ok = s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
  5873  		}
  5874  		return s.newValue2(ssa.OpIMake, dst, itab, data), ok
  5875  	}
  5876  
  5877  	if base.Debug.TypeAssert > 0 {
  5878  		base.WarnfAt(pos, "type assertion inlined")
  5879  	}
  5880  
  5881  	// Converting to a concrete type.
  5882  	direct := types.IsDirectIface(dst)
  5883  	itab := s.newValue1(ssa.OpITab, byteptr, iface) // type word of interface
  5884  	if base.Debug.TypeAssert > 0 {
  5885  		base.WarnfAt(pos, "type assertion inlined")
  5886  	}
  5887  	var wantedFirstWord *ssa.Value
  5888  	if src.IsEmptyInterface() {
  5889  		// Looking for pointer to target type.
  5890  		wantedFirstWord = target
  5891  	} else {
  5892  		// Looking for pointer to itab for target type and source interface.
  5893  		wantedFirstWord = targetItab
  5894  	}
  5895  
  5896  	var tmp ir.Node     // temporary for use with large types
  5897  	var addr *ssa.Value // address of tmp
  5898  	if commaok && !ssa.CanSSA(dst) {
  5899  		// unSSAable type, use temporary.
  5900  		// TODO: get rid of some of these temporaries.
  5901  		tmp, addr = s.temp(pos, dst)
  5902  	}
  5903  
  5904  	cond := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], itab, wantedFirstWord)
  5905  	b := s.endBlock()
  5906  	b.Kind = ssa.BlockIf
  5907  	b.SetControl(cond)
  5908  	b.Likely = ssa.BranchLikely
  5909  
  5910  	bOk := s.f.NewBlock(ssa.BlockPlain)
  5911  	bFail := s.f.NewBlock(ssa.BlockPlain)
  5912  	b.AddEdgeTo(bOk)
  5913  	b.AddEdgeTo(bFail)
  5914  
  5915  	if !commaok {
  5916  		// on failure, panic by calling panicdottype
  5917  		s.startBlock(bFail)
  5918  		taddr := source
  5919  		if taddr == nil {
  5920  			taddr = s.reflectType(src)
  5921  		}
  5922  		if src.IsEmptyInterface() {
  5923  			s.rtcall(ir.Syms.PanicdottypeE, false, nil, itab, target, taddr)
  5924  		} else {
  5925  			s.rtcall(ir.Syms.PanicdottypeI, false, nil, itab, target, taddr)
  5926  		}
  5927  
  5928  		// on success, return data from interface
  5929  		s.startBlock(bOk)
  5930  		if direct {
  5931  			return s.newValue1(ssa.OpIData, dst, iface), nil
  5932  		}
  5933  		p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
  5934  		return s.load(dst, p), nil
  5935  	}
  5936  
  5937  	// commaok is the more complicated case because we have
  5938  	// a control flow merge point.
  5939  	bEnd := s.f.NewBlock(ssa.BlockPlain)
  5940  	// Note that we need a new valVar each time (unlike okVar where we can
  5941  	// reuse the variable) because it might have a different type every time.
  5942  	valVar := ssaMarker("val")
  5943  
  5944  	// type assertion succeeded
  5945  	s.startBlock(bOk)
  5946  	if tmp == nil {
  5947  		if direct {
  5948  			s.vars[valVar] = s.newValue1(ssa.OpIData, dst, iface)
  5949  		} else {
  5950  			p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
  5951  			s.vars[valVar] = s.load(dst, p)
  5952  		}
  5953  	} else {
  5954  		p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
  5955  		s.move(dst, addr, p)
  5956  	}
  5957  	s.vars[okVar] = s.constBool(true)
  5958  	s.endBlock()
  5959  	bOk.AddEdgeTo(bEnd)
  5960  
  5961  	// type assertion failed
  5962  	s.startBlock(bFail)
  5963  	if tmp == nil {
  5964  		s.vars[valVar] = s.zeroVal(dst)
  5965  	} else {
  5966  		s.zero(dst, addr)
  5967  	}
  5968  	s.vars[okVar] = s.constBool(false)
  5969  	s.endBlock()
  5970  	bFail.AddEdgeTo(bEnd)
  5971  
  5972  	// merge point
  5973  	s.startBlock(bEnd)
  5974  	if tmp == nil {
  5975  		res = s.variable(valVar, dst)
  5976  		delete(s.vars, valVar) // no practical effect, just to indicate typVar is no longer live.
  5977  	} else {
  5978  		res = s.load(dst, addr)
  5979  	}
  5980  	resok = s.variable(okVar, types.Types[types.TBOOL])
  5981  	delete(s.vars, okVar) // ditto
  5982  	return res, resok
  5983  }
  5984  
  5985  // temp allocates a temp of type t at position pos
  5986  func (s *state) temp(pos src.XPos, t *types.Type) (*ir.Name, *ssa.Value) {
  5987  	tmp := typecheck.TempAt(pos, s.curfn, t)
  5988  	if t.HasPointers() || (ssa.IsMergeCandidate(tmp) && t != deferstruct()) {
  5989  		s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, tmp, s.mem())
  5990  	}
  5991  	addr := s.addr(tmp)
  5992  	return tmp, addr
  5993  }
  5994  
  5995  // variable returns the value of a variable at the current location.
  5996  func (s *state) variable(n ir.Node, t *types.Type) *ssa.Value {
  5997  	v := s.vars[n]
  5998  	if v != nil {
  5999  		return v
  6000  	}
  6001  	v = s.fwdVars[n]
  6002  	if v != nil {
  6003  		return v
  6004  	}
  6005  
  6006  	if s.curBlock == s.f.Entry {
  6007  		// No variable should be live at entry.
  6008  		s.f.Fatalf("value %v (%v) incorrectly live at entry", n, v)
  6009  	}
  6010  	// Make a FwdRef, which records a value that's live on block input.
  6011  	// We'll find the matching definition as part of insertPhis.
  6012  	v = s.newValue0A(ssa.OpFwdRef, t, fwdRefAux{N: n})
  6013  	s.fwdVars[n] = v
  6014  	if n.Op() == ir.ONAME {
  6015  		s.addNamedValue(n.(*ir.Name), v)
  6016  	}
  6017  	return v
  6018  }
  6019  
  6020  func (s *state) mem() *ssa.Value {
  6021  	return s.variable(memVar, types.TypeMem)
  6022  }
  6023  
  6024  func (s *state) addNamedValue(n *ir.Name, v *ssa.Value) {
  6025  	if n.Class == ir.Pxxx {
  6026  		// Don't track our marker nodes (memVar etc.).
  6027  		return
  6028  	}
  6029  	if ir.IsAutoTmp(n) {
  6030  		// Don't track temporary variables.
  6031  		return
  6032  	}
  6033  	if n.Class == ir.PPARAMOUT {
  6034  		// Don't track named output values.  This prevents return values
  6035  		// from being assigned too early. See #14591 and #14762. TODO: allow this.
  6036  		return
  6037  	}
  6038  	loc := ssa.LocalSlot{N: n, Type: n.Type(), Off: 0}
  6039  	values, ok := s.f.NamedValues[loc]
  6040  	if !ok {
  6041  		s.f.Names = append(s.f.Names, &loc)
  6042  		s.f.CanonicalLocalSlots[loc] = &loc
  6043  	}
  6044  	s.f.NamedValues[loc] = append(values, v)
  6045  }
  6046  
  6047  // Branch is an unresolved branch.
  6048  type Branch struct {
  6049  	P *obj.Prog  // branch instruction
  6050  	B *ssa.Block // target
  6051  }
  6052  
  6053  // State contains state needed during Prog generation.
  6054  type State struct {
  6055  	ABI obj.ABI
  6056  
  6057  	pp *objw.Progs
  6058  
  6059  	// Branches remembers all the branch instructions we've seen
  6060  	// and where they would like to go.
  6061  	Branches []Branch
  6062  
  6063  	// JumpTables remembers all the jump tables we've seen.
  6064  	JumpTables []*ssa.Block
  6065  
  6066  	// bstart remembers where each block starts (indexed by block ID)
  6067  	bstart []*obj.Prog
  6068  
  6069  	maxarg int64 // largest frame size for arguments to calls made by the function
  6070  
  6071  	// Map from GC safe points to liveness index, generated by
  6072  	// liveness analysis.
  6073  	livenessMap liveness.Map
  6074  
  6075  	// partLiveArgs includes arguments that may be partially live, for which we
  6076  	// need to generate instructions that spill the argument registers.
  6077  	partLiveArgs map[*ir.Name]bool
  6078  
  6079  	// lineRunStart records the beginning of the current run of instructions
  6080  	// within a single block sharing the same line number
  6081  	// Used to move statement marks to the beginning of such runs.
  6082  	lineRunStart *obj.Prog
  6083  
  6084  	// wasm: The number of values on the WebAssembly stack. This is only used as a safeguard.
  6085  	OnWasmStackSkipped int
  6086  }
  6087  
  6088  func (s *State) FuncInfo() *obj.FuncInfo {
  6089  	return s.pp.CurFunc.LSym.Func()
  6090  }
  6091  
  6092  // Prog appends a new Prog.
  6093  func (s *State) Prog(as obj.As) *obj.Prog {
  6094  	p := s.pp.Prog(as)
  6095  	if objw.LosesStmtMark(as) {
  6096  		return p
  6097  	}
  6098  	// Float a statement start to the beginning of any same-line run.
  6099  	// lineRunStart is reset at block boundaries, which appears to work well.
  6100  	if s.lineRunStart == nil || s.lineRunStart.Pos.Line() != p.Pos.Line() {
  6101  		s.lineRunStart = p
  6102  	} else if p.Pos.IsStmt() == src.PosIsStmt {
  6103  		s.lineRunStart.Pos = s.lineRunStart.Pos.WithIsStmt()
  6104  		p.Pos = p.Pos.WithNotStmt()
  6105  	}
  6106  	return p
  6107  }
  6108  
  6109  // Pc returns the current Prog.
  6110  func (s *State) Pc() *obj.Prog {
  6111  	return s.pp.Next
  6112  }
  6113  
  6114  // SetPos sets the current source position.
  6115  func (s *State) SetPos(pos src.XPos) {
  6116  	s.pp.Pos = pos
  6117  }
  6118  
  6119  // Br emits a single branch instruction and returns the instruction.
  6120  // Not all architectures need the returned instruction, but otherwise
  6121  // the boilerplate is common to all.
  6122  func (s *State) Br(op obj.As, target *ssa.Block) *obj.Prog {
  6123  	p := s.Prog(op)
  6124  	p.To.Type = obj.TYPE_BRANCH
  6125  	s.Branches = append(s.Branches, Branch{P: p, B: target})
  6126  	return p
  6127  }
  6128  
  6129  // DebugFriendlySetPosFrom adjusts Pos.IsStmt subject to heuristics
  6130  // that reduce "jumpy" line number churn when debugging.
  6131  // Spill/fill/copy instructions from the register allocator,
  6132  // phi functions, and instructions with a no-pos position
  6133  // are examples of instructions that can cause churn.
  6134  func (s *State) DebugFriendlySetPosFrom(v *ssa.Value) {
  6135  	switch v.Op {
  6136  	case ssa.OpPhi, ssa.OpCopy, ssa.OpLoadReg, ssa.OpStoreReg:
  6137  		// These are not statements
  6138  		s.SetPos(v.Pos.WithNotStmt())
  6139  	default:
  6140  		p := v.Pos
  6141  		if p != src.NoXPos {
  6142  			// If the position is defined, update the position.
  6143  			// Also convert default IsStmt to NotStmt; only
  6144  			// explicit statement boundaries should appear
  6145  			// in the generated code.
  6146  			if p.IsStmt() != src.PosIsStmt {
  6147  				if s.pp.Pos.IsStmt() == src.PosIsStmt && s.pp.Pos.SameFileAndLine(p) {
  6148  					// If s.pp.Pos already has a statement mark, then it was set here (below) for
  6149  					// the previous value.  If an actual instruction had been emitted for that
  6150  					// value, then the statement mark would have been reset.  Since the statement
  6151  					// mark of s.pp.Pos was not reset, this position (file/line) still needs a
  6152  					// statement mark on an instruction.  If file and line for this value are
  6153  					// the same as the previous value, then the first instruction for this
  6154  					// value will work to take the statement mark.  Return early to avoid
  6155  					// resetting the statement mark.
  6156  					//
  6157  					// The reset of s.pp.Pos occurs in (*Progs).Prog() -- if it emits
  6158  					// an instruction, and the instruction's statement mark was set,
  6159  					// and it is not one of the LosesStmtMark instructions,
  6160  					// then Prog() resets the statement mark on the (*Progs).Pos.
  6161  					return
  6162  				}
  6163  				p = p.WithNotStmt()
  6164  				// Calls use the pos attached to v, but copy the statement mark from State
  6165  			}
  6166  			s.SetPos(p)
  6167  		} else {
  6168  			s.SetPos(s.pp.Pos.WithNotStmt())
  6169  		}
  6170  	}
  6171  }
  6172  
  6173  // emit argument info (locations on stack) for traceback.
  6174  func emitArgInfo(e *ssafn, f *ssa.Func, pp *objw.Progs) {
  6175  	ft := e.curfn.Type()
  6176  	if ft.NumRecvs() == 0 && ft.NumParams() == 0 {
  6177  		return
  6178  	}
  6179  
  6180  	x := EmitArgInfo(e.curfn, f.OwnAux.ABIInfo())
  6181  	x.Set(obj.AttrContentAddressable, true)
  6182  	e.curfn.LSym.Func().ArgInfo = x
  6183  
  6184  	// Emit a funcdata pointing at the arg info data.
  6185  	p := pp.Prog(obj.AFUNCDATA)
  6186  	p.From.SetConst(rtabi.FUNCDATA_ArgInfo)
  6187  	p.To.Type = obj.TYPE_MEM
  6188  	p.To.Name = obj.NAME_EXTERN
  6189  	p.To.Sym = x
  6190  }
  6191  
  6192  // emit argument info (locations on stack) of f for traceback.
  6193  func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
  6194  	x := base.Ctxt.Lookup(fmt.Sprintf("%s.arginfo%d", f.LSym.Name, f.ABI))
  6195  	// NOTE: do not set ContentAddressable here. This may be referenced from
  6196  	// assembly code by name (in this case f is a declaration).
  6197  	// Instead, set it in emitArgInfo above.
  6198  
  6199  	PtrSize := int64(types.PtrSize)
  6200  	uintptrTyp := types.Types[types.TUINTPTR]
  6201  
  6202  	isAggregate := func(t *types.Type) bool {
  6203  		return t.IsStruct() || t.IsArray() || t.IsComplex() || t.IsInterface() || t.IsString() || t.IsSlice()
  6204  	}
  6205  
  6206  	wOff := 0
  6207  	n := 0
  6208  	writebyte := func(o uint8) { wOff = objw.Uint8(x, wOff, o) }
  6209  
  6210  	// Write one non-aggregate arg/field/element.
  6211  	write1 := func(sz, offset int64) {
  6212  		if offset >= rtabi.TraceArgsSpecial {
  6213  			writebyte(rtabi.TraceArgsOffsetTooLarge)
  6214  		} else {
  6215  			writebyte(uint8(offset))
  6216  			writebyte(uint8(sz))
  6217  		}
  6218  		n++
  6219  	}
  6220  
  6221  	// Visit t recursively and write it out.
  6222  	// Returns whether to continue visiting.
  6223  	var visitType func(baseOffset int64, t *types.Type, depth int) bool
  6224  	visitType = func(baseOffset int64, t *types.Type, depth int) bool {
  6225  		if n >= rtabi.TraceArgsLimit {
  6226  			writebyte(rtabi.TraceArgsDotdotdot)
  6227  			return false
  6228  		}
  6229  		if !isAggregate(t) {
  6230  			write1(t.Size(), baseOffset)
  6231  			return true
  6232  		}
  6233  		writebyte(rtabi.TraceArgsStartAgg)
  6234  		depth++
  6235  		if depth >= rtabi.TraceArgsMaxDepth {
  6236  			writebyte(rtabi.TraceArgsDotdotdot)
  6237  			writebyte(rtabi.TraceArgsEndAgg)
  6238  			n++
  6239  			return true
  6240  		}
  6241  		switch {
  6242  		case t.IsInterface(), t.IsString():
  6243  			_ = visitType(baseOffset, uintptrTyp, depth) &&
  6244  				visitType(baseOffset+PtrSize, uintptrTyp, depth)
  6245  		case t.IsSlice():
  6246  			_ = visitType(baseOffset, uintptrTyp, depth) &&
  6247  				visitType(baseOffset+PtrSize, uintptrTyp, depth) &&
  6248  				visitType(baseOffset+PtrSize*2, uintptrTyp, depth)
  6249  		case t.IsComplex():
  6250  			_ = visitType(baseOffset, types.FloatForComplex(t), depth) &&
  6251  				visitType(baseOffset+t.Size()/2, types.FloatForComplex(t), depth)
  6252  		case t.IsArray():
  6253  			if t.NumElem() == 0 {
  6254  				n++ // {} counts as a component
  6255  				break
  6256  			}
  6257  			for i := int64(0); i < t.NumElem(); i++ {
  6258  				if !visitType(baseOffset, t.Elem(), depth) {
  6259  					break
  6260  				}
  6261  				baseOffset += t.Elem().Size()
  6262  			}
  6263  		case t.IsStruct():
  6264  			if t.NumFields() == 0 {
  6265  				n++ // {} counts as a component
  6266  				break
  6267  			}
  6268  			for _, field := range t.Fields() {
  6269  				if !visitType(baseOffset+field.Offset, field.Type, depth) {
  6270  					break
  6271  				}
  6272  			}
  6273  		}
  6274  		writebyte(rtabi.TraceArgsEndAgg)
  6275  		return true
  6276  	}
  6277  
  6278  	start := 0
  6279  	if strings.Contains(f.LSym.Name, "[") {
  6280  		// Skip the dictionary argument - it is implicit and the user doesn't need to see it.
  6281  		start = 1
  6282  	}
  6283  
  6284  	for _, a := range abiInfo.InParams()[start:] {
  6285  		if !visitType(a.FrameOffset(abiInfo), a.Type, 0) {
  6286  			break
  6287  		}
  6288  	}
  6289  	writebyte(rtabi.TraceArgsEndSeq)
  6290  	if wOff > rtabi.TraceArgsMaxLen {
  6291  		base.Fatalf("ArgInfo too large")
  6292  	}
  6293  
  6294  	return x
  6295  }
  6296  
  6297  // for wrapper, emit info of wrapped function.
  6298  func emitWrappedFuncInfo(e *ssafn, pp *objw.Progs) {
  6299  	if base.Ctxt.Flag_linkshared {
  6300  		// Relative reference (SymPtrOff) to another shared object doesn't work.
  6301  		// Unfortunate.
  6302  		return
  6303  	}
  6304  
  6305  	wfn := e.curfn.WrappedFunc
  6306  	if wfn == nil {
  6307  		return
  6308  	}
  6309  
  6310  	wsym := wfn.Linksym()
  6311  	x := base.Ctxt.LookupInit(fmt.Sprintf("%s.wrapinfo", wsym.Name), func(x *obj.LSym) {
  6312  		objw.SymPtrOff(x, 0, wsym)
  6313  		x.Set(obj.AttrContentAddressable, true)
  6314  	})
  6315  	e.curfn.LSym.Func().WrapInfo = x
  6316  
  6317  	// Emit a funcdata pointing at the wrap info data.
  6318  	p := pp.Prog(obj.AFUNCDATA)
  6319  	p.From.SetConst(rtabi.FUNCDATA_WrapInfo)
  6320  	p.To.Type = obj.TYPE_MEM
  6321  	p.To.Name = obj.NAME_EXTERN
  6322  	p.To.Sym = x
  6323  }
  6324  
  6325  // genssa appends entries to pp for each instruction in f.
  6326  func genssa(f *ssa.Func, pp *objw.Progs) {
  6327  	var s State
  6328  	s.ABI = f.OwnAux.Fn.ABI()
  6329  
  6330  	e := f.Frontend().(*ssafn)
  6331  
  6332  	s.livenessMap, s.partLiveArgs = liveness.Compute(e.curfn, f, e.stkptrsize, pp)
  6333  	emitArgInfo(e, f, pp)
  6334  	argLiveBlockMap, argLiveValueMap := liveness.ArgLiveness(e.curfn, f, pp)
  6335  
  6336  	openDeferInfo := e.curfn.LSym.Func().OpenCodedDeferInfo
  6337  	if openDeferInfo != nil {
  6338  		// This function uses open-coded defers -- write out the funcdata
  6339  		// info that we computed at the end of genssa.
  6340  		p := pp.Prog(obj.AFUNCDATA)
  6341  		p.From.SetConst(rtabi.FUNCDATA_OpenCodedDeferInfo)
  6342  		p.To.Type = obj.TYPE_MEM
  6343  		p.To.Name = obj.NAME_EXTERN
  6344  		p.To.Sym = openDeferInfo
  6345  	}
  6346  
  6347  	emitWrappedFuncInfo(e, pp)
  6348  
  6349  	// Remember where each block starts.
  6350  	s.bstart = make([]*obj.Prog, f.NumBlocks())
  6351  	s.pp = pp
  6352  	var progToValue map[*obj.Prog]*ssa.Value
  6353  	var progToBlock map[*obj.Prog]*ssa.Block
  6354  	var valueToProgAfter []*obj.Prog // The first Prog following computation of a value v; v is visible at this point.
  6355  	gatherPrintInfo := f.PrintOrHtmlSSA || ssa.GenssaDump[f.Name]
  6356  	if gatherPrintInfo {
  6357  		progToValue = make(map[*obj.Prog]*ssa.Value, f.NumValues())
  6358  		progToBlock = make(map[*obj.Prog]*ssa.Block, f.NumBlocks())
  6359  		f.Logf("genssa %s\n", f.Name)
  6360  		progToBlock[s.pp.Next] = f.Blocks[0]
  6361  	}
  6362  
  6363  	if base.Ctxt.Flag_locationlists {
  6364  		if cap(f.Cache.ValueToProgAfter) < f.NumValues() {
  6365  			f.Cache.ValueToProgAfter = make([]*obj.Prog, f.NumValues())
  6366  		}
  6367  		valueToProgAfter = f.Cache.ValueToProgAfter[:f.NumValues()]
  6368  		for i := range valueToProgAfter {
  6369  			valueToProgAfter[i] = nil
  6370  		}
  6371  	}
  6372  
  6373  	// If the very first instruction is not tagged as a statement,
  6374  	// debuggers may attribute it to previous function in program.
  6375  	firstPos := src.NoXPos
  6376  	for _, v := range f.Entry.Values {
  6377  		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 {
  6378  			firstPos = v.Pos
  6379  			v.Pos = firstPos.WithDefaultStmt()
  6380  			break
  6381  		}
  6382  	}
  6383  
  6384  	// inlMarks has an entry for each Prog that implements an inline mark.
  6385  	// It maps from that Prog to the global inlining id of the inlined body
  6386  	// which should unwind to this Prog's location.
  6387  	var inlMarks map[*obj.Prog]int32
  6388  	var inlMarkList []*obj.Prog
  6389  
  6390  	// inlMarksByPos maps from a (column 1) source position to the set of
  6391  	// Progs that are in the set above and have that source position.
  6392  	var inlMarksByPos map[src.XPos][]*obj.Prog
  6393  
  6394  	var argLiveIdx int = -1 // argument liveness info index
  6395  
  6396  	// These control cache line alignment; if the required portion of
  6397  	// a cache line is not available, then pad to obtain cache line
  6398  	// alignment.  Not implemented on all architectures, may not be
  6399  	// useful on all architectures.
  6400  	var hotAlign, hotRequire int64
  6401  
  6402  	if base.Debug.AlignHot > 0 {
  6403  		switch base.Ctxt.Arch.Name {
  6404  		// enable this on a case-by-case basis, with benchmarking.
  6405  		// currently shown:
  6406  		//   good for amd64
  6407  		//   not helpful for Apple Silicon
  6408  		//
  6409  		case "amd64", "386":
  6410  			// Align to 64 if 31 or fewer bytes remain in a cache line
  6411  			// benchmarks a little better than always aligning, and also
  6412  			// adds slightly less to the (PGO-compiled) binary size.
  6413  			hotAlign = 64
  6414  			hotRequire = 31
  6415  		}
  6416  	}
  6417  
  6418  	// Emit basic blocks
  6419  	for i, b := range f.Blocks {
  6420  
  6421  		s.lineRunStart = nil
  6422  		s.SetPos(s.pp.Pos.WithNotStmt()) // It needs a non-empty Pos, but cannot be a statement boundary (yet).
  6423  
  6424  		if hotAlign > 0 && b.Hotness&ssa.HotPgoInitial == ssa.HotPgoInitial {
  6425  			// So far this has only been shown profitable for PGO-hot loop headers.
  6426  			// The Hotness values allows distinctions between initial blocks that are "hot" or not, and "flow-in" or not.
  6427  			// Currently only the initial blocks of loops are tagged in this way;
  6428  			// there are no blocks tagged "pgo-hot" that are not also tagged "initial".
  6429  			// TODO more heuristics, more architectures.
  6430  			p := s.pp.Prog(obj.APCALIGNMAX)
  6431  			p.From.SetConst(hotAlign)
  6432  			p.To.SetConst(hotRequire)
  6433  		}
  6434  
  6435  		s.bstart[b.ID] = s.pp.Next
  6436  
  6437  		if idx, ok := argLiveBlockMap[b.ID]; ok && idx != argLiveIdx {
  6438  			argLiveIdx = idx
  6439  			p := s.pp.Prog(obj.APCDATA)
  6440  			p.From.SetConst(rtabi.PCDATA_ArgLiveIndex)
  6441  			p.To.SetConst(int64(idx))
  6442  		}
  6443  
  6444  		// Emit values in block
  6445  		Arch.SSAMarkMoves(&s, b)
  6446  		for _, v := range b.Values {
  6447  			x := s.pp.Next
  6448  			s.DebugFriendlySetPosFrom(v)
  6449  
  6450  			if v.Op.ResultInArg0() && v.ResultReg() != v.Args[0].Reg() {
  6451  				v.Fatalf("input[0] and output not in same register %s", v.LongString())
  6452  			}
  6453  
  6454  			switch v.Op {
  6455  			case ssa.OpInitMem:
  6456  				// memory arg needs no code
  6457  			case ssa.OpArg:
  6458  				// input args need no code
  6459  			case ssa.OpSP, ssa.OpSB:
  6460  				// nothing to do
  6461  			case ssa.OpSelect0, ssa.OpSelect1, ssa.OpSelectN, ssa.OpMakeResult:
  6462  				// nothing to do
  6463  			case ssa.OpGetG:
  6464  				// nothing to do when there's a g register,
  6465  				// and checkLower complains if there's not
  6466  			case ssa.OpVarDef, ssa.OpVarLive, ssa.OpKeepAlive, ssa.OpWBend:
  6467  				// nothing to do; already used by liveness
  6468  			case ssa.OpPhi:
  6469  				CheckLoweredPhi(v)
  6470  			case ssa.OpConvert:
  6471  				// nothing to do; no-op conversion for liveness
  6472  				if v.Args[0].Reg() != v.Reg() {
  6473  					v.Fatalf("OpConvert should be a no-op: %s; %s", v.Args[0].LongString(), v.LongString())
  6474  				}
  6475  			case ssa.OpInlMark:
  6476  				p := Arch.Ginsnop(s.pp)
  6477  				if inlMarks == nil {
  6478  					inlMarks = map[*obj.Prog]int32{}
  6479  					inlMarksByPos = map[src.XPos][]*obj.Prog{}
  6480  				}
  6481  				inlMarks[p] = v.AuxInt32()
  6482  				inlMarkList = append(inlMarkList, p)
  6483  				pos := v.Pos.AtColumn1()
  6484  				inlMarksByPos[pos] = append(inlMarksByPos[pos], p)
  6485  				firstPos = src.NoXPos
  6486  
  6487  			default:
  6488  				// Special case for first line in function; move it to the start (which cannot be a register-valued instruction)
  6489  				if firstPos != src.NoXPos && v.Op != ssa.OpArgIntReg && v.Op != ssa.OpArgFloatReg && v.Op != ssa.OpLoadReg && v.Op != ssa.OpStoreReg {
  6490  					s.SetPos(firstPos)
  6491  					firstPos = src.NoXPos
  6492  				}
  6493  				// Attach this safe point to the next
  6494  				// instruction.
  6495  				s.pp.NextLive = s.livenessMap.Get(v)
  6496  				s.pp.NextUnsafe = s.livenessMap.GetUnsafe(v)
  6497  
  6498  				// let the backend handle it
  6499  				Arch.SSAGenValue(&s, v)
  6500  			}
  6501  
  6502  			if idx, ok := argLiveValueMap[v.ID]; ok && idx != argLiveIdx {
  6503  				argLiveIdx = idx
  6504  				p := s.pp.Prog(obj.APCDATA)
  6505  				p.From.SetConst(rtabi.PCDATA_ArgLiveIndex)
  6506  				p.To.SetConst(int64(idx))
  6507  			}
  6508  
  6509  			if base.Ctxt.Flag_locationlists {
  6510  				valueToProgAfter[v.ID] = s.pp.Next
  6511  			}
  6512  
  6513  			if gatherPrintInfo {
  6514  				for ; x != s.pp.Next; x = x.Link {
  6515  					progToValue[x] = v
  6516  				}
  6517  			}
  6518  		}
  6519  		// If this is an empty infinite loop, stick a hardware NOP in there so that debuggers are less confused.
  6520  		if s.bstart[b.ID] == s.pp.Next && len(b.Succs) == 1 && b.Succs[0].Block() == b {
  6521  			p := Arch.Ginsnop(s.pp)
  6522  			p.Pos = p.Pos.WithIsStmt()
  6523  			if b.Pos == src.NoXPos {
  6524  				b.Pos = p.Pos // It needs a file, otherwise a no-file non-zero line causes confusion.  See #35652.
  6525  				if b.Pos == src.NoXPos {
  6526  					b.Pos = s.pp.Text.Pos // Sometimes p.Pos is empty.  See #35695.
  6527  				}
  6528  			}
  6529  			b.Pos = b.Pos.WithBogusLine() // Debuggers are not good about infinite loops, force a change in line number
  6530  		}
  6531  
  6532  		// Set unsafe mark for any end-of-block generated instructions
  6533  		// (normally, conditional or unconditional branches).
  6534  		// This is particularly important for empty blocks, as there
  6535  		// are no values to inherit the unsafe mark from.
  6536  		s.pp.NextUnsafe = s.livenessMap.GetUnsafeBlock(b)
  6537  
  6538  		// Emit control flow instructions for block
  6539  		var next *ssa.Block
  6540  		if i < len(f.Blocks)-1 && base.Flag.N == 0 {
  6541  			// If -N, leave next==nil so every block with successors
  6542  			// ends in a JMP (except call blocks - plive doesn't like
  6543  			// select{send,recv} followed by a JMP call).  Helps keep
  6544  			// line numbers for otherwise empty blocks.
  6545  			next = f.Blocks[i+1]
  6546  		}
  6547  		x := s.pp.Next
  6548  		s.SetPos(b.Pos)
  6549  		Arch.SSAGenBlock(&s, b, next)
  6550  		if gatherPrintInfo {
  6551  			for ; x != s.pp.Next; x = x.Link {
  6552  				progToBlock[x] = b
  6553  			}
  6554  		}
  6555  	}
  6556  	if f.Blocks[len(f.Blocks)-1].Kind == ssa.BlockExit {
  6557  		// We need the return address of a panic call to
  6558  		// still be inside the function in question. So if
  6559  		// it ends in a call which doesn't return, add a
  6560  		// nop (which will never execute) after the call.
  6561  		Arch.Ginsnop(s.pp)
  6562  	}
  6563  	if openDeferInfo != nil {
  6564  		// When doing open-coded defers, generate a disconnected call to
  6565  		// deferreturn and a return. This will be used to during panic
  6566  		// recovery to unwind the stack and return back to the runtime.
  6567  		s.pp.NextLive = s.livenessMap.DeferReturn
  6568  		p := s.pp.Prog(obj.ACALL)
  6569  		p.To.Type = obj.TYPE_MEM
  6570  		p.To.Name = obj.NAME_EXTERN
  6571  		p.To.Sym = ir.Syms.Deferreturn
  6572  
  6573  		// Load results into registers. So when a deferred function
  6574  		// recovers a panic, it will return to caller with right results.
  6575  		// The results are already in memory, because they are not SSA'd
  6576  		// when the function has defers (see canSSAName).
  6577  		for _, o := range f.OwnAux.ABIInfo().OutParams() {
  6578  			n := o.Name
  6579  			rts, offs := o.RegisterTypesAndOffsets()
  6580  			for i := range o.Registers {
  6581  				Arch.LoadRegResult(&s, f, rts[i], ssa.ObjRegForAbiReg(o.Registers[i], f.Config), n, offs[i])
  6582  			}
  6583  		}
  6584  
  6585  		s.pp.Prog(obj.ARET)
  6586  	}
  6587  
  6588  	if inlMarks != nil {
  6589  		hasCall := false
  6590  
  6591  		// We have some inline marks. Try to find other instructions we're
  6592  		// going to emit anyway, and use those instructions instead of the
  6593  		// inline marks.
  6594  		for p := s.pp.Text; p != nil; p = p.Link {
  6595  			if p.As == obj.ANOP || p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT ||
  6596  				p.As == obj.APCALIGN || p.As == obj.APCALIGNMAX || Arch.LinkArch.Family == sys.Wasm {
  6597  				// Don't use 0-sized instructions as inline marks, because we need
  6598  				// to identify inline mark instructions by pc offset.
  6599  				// (Some of these instructions are sometimes zero-sized, sometimes not.
  6600  				// We must not use anything that even might be zero-sized.)
  6601  				// TODO: are there others?
  6602  				continue
  6603  			}
  6604  			if _, ok := inlMarks[p]; ok {
  6605  				// Don't use inline marks themselves. We don't know
  6606  				// whether they will be zero-sized or not yet.
  6607  				continue
  6608  			}
  6609  			if p.As == obj.ACALL || p.As == obj.ADUFFCOPY || p.As == obj.ADUFFZERO {
  6610  				hasCall = true
  6611  			}
  6612  			pos := p.Pos.AtColumn1()
  6613  			marks := inlMarksByPos[pos]
  6614  			if len(marks) == 0 {
  6615  				continue
  6616  			}
  6617  			for _, m := range marks {
  6618  				// We found an instruction with the same source position as
  6619  				// some of the inline marks.
  6620  				// Use this instruction instead.
  6621  				p.Pos = p.Pos.WithIsStmt() // promote position to a statement
  6622  				s.pp.CurFunc.LSym.Func().AddInlMark(p, inlMarks[m])
  6623  				// Make the inline mark a real nop, so it doesn't generate any code.
  6624  				m.As = obj.ANOP
  6625  				m.Pos = src.NoXPos
  6626  				m.From = obj.Addr{}
  6627  				m.To = obj.Addr{}
  6628  			}
  6629  			delete(inlMarksByPos, pos)
  6630  		}
  6631  		// Any unmatched inline marks now need to be added to the inlining tree (and will generate a nop instruction).
  6632  		for _, p := range inlMarkList {
  6633  			if p.As != obj.ANOP {
  6634  				s.pp.CurFunc.LSym.Func().AddInlMark(p, inlMarks[p])
  6635  			}
  6636  		}
  6637  
  6638  		if e.stksize == 0 && !hasCall {
  6639  			// Frameless leaf function. It doesn't need any preamble,
  6640  			// so make sure its first instruction isn't from an inlined callee.
  6641  			// If it is, add a nop at the start of the function with a position
  6642  			// equal to the start of the function.
  6643  			// This ensures that runtime.FuncForPC(uintptr(reflect.ValueOf(fn).Pointer())).Name()
  6644  			// returns the right answer. See issue 58300.
  6645  			for p := s.pp.Text; p != nil; p = p.Link {
  6646  				if p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT || p.As == obj.ANOP {
  6647  					continue
  6648  				}
  6649  				if base.Ctxt.PosTable.Pos(p.Pos).Base().InliningIndex() >= 0 {
  6650  					// Make a real (not 0-sized) nop.
  6651  					nop := Arch.Ginsnop(s.pp)
  6652  					nop.Pos = e.curfn.Pos().WithIsStmt()
  6653  
  6654  					// Unfortunately, Ginsnop puts the instruction at the
  6655  					// end of the list. Move it up to just before p.
  6656  
  6657  					// Unlink from the current list.
  6658  					for x := s.pp.Text; x != nil; x = x.Link {
  6659  						if x.Link == nop {
  6660  							x.Link = nop.Link
  6661  							break
  6662  						}
  6663  					}
  6664  					// Splice in right before p.
  6665  					for x := s.pp.Text; x != nil; x = x.Link {
  6666  						if x.Link == p {
  6667  							nop.Link = p
  6668  							x.Link = nop
  6669  							break
  6670  						}
  6671  					}
  6672  				}
  6673  				break
  6674  			}
  6675  		}
  6676  	}
  6677  
  6678  	if base.Ctxt.Flag_locationlists {
  6679  		var debugInfo *ssa.FuncDebug
  6680  		debugInfo = e.curfn.DebugInfo.(*ssa.FuncDebug)
  6681  		if e.curfn.ABI == obj.ABIInternal && base.Flag.N != 0 {
  6682  			ssa.BuildFuncDebugNoOptimized(base.Ctxt, f, base.Debug.LocationLists > 1, StackOffset, debugInfo)
  6683  		} else {
  6684  			ssa.BuildFuncDebug(base.Ctxt, f, base.Debug.LocationLists, StackOffset, debugInfo)
  6685  		}
  6686  		bstart := s.bstart
  6687  		idToIdx := make([]int, f.NumBlocks())
  6688  		for i, b := range f.Blocks {
  6689  			idToIdx[b.ID] = i
  6690  		}
  6691  		// Register a callback that will be used later to fill in PCs into location
  6692  		// lists. At the moment, Prog.Pc is a sequence number; it's not a real PC
  6693  		// until after assembly, so the translation needs to be deferred.
  6694  		debugInfo.GetPC = func(b, v ssa.ID) int64 {
  6695  			switch v {
  6696  			case ssa.BlockStart.ID:
  6697  				if b == f.Entry.ID {
  6698  					return 0 // Start at the very beginning, at the assembler-generated prologue.
  6699  					// this should only happen for function args (ssa.OpArg)
  6700  				}
  6701  				return bstart[b].Pc
  6702  			case ssa.BlockEnd.ID:
  6703  				blk := f.Blocks[idToIdx[b]]
  6704  				nv := len(blk.Values)
  6705  				return valueToProgAfter[blk.Values[nv-1].ID].Pc
  6706  			case ssa.FuncEnd.ID:
  6707  				return e.curfn.LSym.Size
  6708  			default:
  6709  				return valueToProgAfter[v].Pc
  6710  			}
  6711  		}
  6712  	}
  6713  
  6714  	// Resolve branches, and relax DefaultStmt into NotStmt
  6715  	for _, br := range s.Branches {
  6716  		br.P.To.SetTarget(s.bstart[br.B.ID])
  6717  		if br.P.Pos.IsStmt() != src.PosIsStmt {
  6718  			br.P.Pos = br.P.Pos.WithNotStmt()
  6719  		} else if v0 := br.B.FirstPossibleStmtValue(); v0 != nil && v0.Pos.Line() == br.P.Pos.Line() && v0.Pos.IsStmt() == src.PosIsStmt {
  6720  			br.P.Pos = br.P.Pos.WithNotStmt()
  6721  		}
  6722  
  6723  	}
  6724  
  6725  	// Resolve jump table destinations.
  6726  	for _, jt := range s.JumpTables {
  6727  		// Convert from *Block targets to *Prog targets.
  6728  		targets := make([]*obj.Prog, len(jt.Succs))
  6729  		for i, e := range jt.Succs {
  6730  			targets[i] = s.bstart[e.Block().ID]
  6731  		}
  6732  		// Add to list of jump tables to be resolved at assembly time.
  6733  		// The assembler converts from *Prog entries to absolute addresses
  6734  		// once it knows instruction byte offsets.
  6735  		fi := s.pp.CurFunc.LSym.Func()
  6736  		fi.JumpTables = append(fi.JumpTables, obj.JumpTable{Sym: jt.Aux.(*obj.LSym), Targets: targets})
  6737  	}
  6738  
  6739  	if e.log { // spew to stdout
  6740  		filename := ""
  6741  		for p := s.pp.Text; p != nil; p = p.Link {
  6742  			if p.Pos.IsKnown() && p.InnermostFilename() != filename {
  6743  				filename = p.InnermostFilename()
  6744  				f.Logf("# %s\n", filename)
  6745  			}
  6746  
  6747  			var s string
  6748  			if v, ok := progToValue[p]; ok {
  6749  				s = v.String()
  6750  			} else if b, ok := progToBlock[p]; ok {
  6751  				s = b.String()
  6752  			} else {
  6753  				s = "   " // most value and branch strings are 2-3 characters long
  6754  			}
  6755  			f.Logf(" %-6s\t%.5d (%s)\t%s\n", s, p.Pc, p.InnermostLineNumber(), p.InstructionString())
  6756  		}
  6757  	}
  6758  	if f.HTMLWriter != nil { // spew to ssa.html
  6759  		var buf strings.Builder
  6760  		buf.WriteString("<code>")
  6761  		buf.WriteString("<dl class=\"ssa-gen\">")
  6762  		filename := ""
  6763  		for p := s.pp.Text; p != nil; p = p.Link {
  6764  			// Don't spam every line with the file name, which is often huge.
  6765  			// Only print changes, and "unknown" is not a change.
  6766  			if p.Pos.IsKnown() && p.InnermostFilename() != filename {
  6767  				filename = p.InnermostFilename()
  6768  				buf.WriteString("<dt class=\"ssa-prog-src\"></dt><dd class=\"ssa-prog\">")
  6769  				buf.WriteString(html.EscapeString("# " + filename))
  6770  				buf.WriteString("</dd>")
  6771  			}
  6772  
  6773  			buf.WriteString("<dt class=\"ssa-prog-src\">")
  6774  			if v, ok := progToValue[p]; ok {
  6775  				buf.WriteString(v.HTML())
  6776  			} else if b, ok := progToBlock[p]; ok {
  6777  				buf.WriteString("<b>" + b.HTML() + "</b>")
  6778  			}
  6779  			buf.WriteString("</dt>")
  6780  			buf.WriteString("<dd class=\"ssa-prog\">")
  6781  			fmt.Fprintf(&buf, "%.5d <span class=\"l%v line-number\">(%s)</span> %s", p.Pc, p.InnermostLineNumber(), p.InnermostLineNumberHTML(), html.EscapeString(p.InstructionString()))
  6782  			buf.WriteString("</dd>")
  6783  		}
  6784  		buf.WriteString("</dl>")
  6785  		buf.WriteString("</code>")
  6786  		f.HTMLWriter.WriteColumn("genssa", "genssa", "ssa-prog", buf.String())
  6787  	}
  6788  	if ssa.GenssaDump[f.Name] {
  6789  		fi := f.DumpFileForPhase("genssa")
  6790  		if fi != nil {
  6791  
  6792  			// inliningDiffers if any filename changes or if any line number except the innermost (last index) changes.
  6793  			inliningDiffers := func(a, b []src.Pos) bool {
  6794  				if len(a) != len(b) {
  6795  					return true
  6796  				}
  6797  				for i := range a {
  6798  					if a[i].Filename() != b[i].Filename() {
  6799  						return true
  6800  					}
  6801  					if i != len(a)-1 && a[i].Line() != b[i].Line() {
  6802  						return true
  6803  					}
  6804  				}
  6805  				return false
  6806  			}
  6807  
  6808  			var allPosOld []src.Pos
  6809  			var allPos []src.Pos
  6810  
  6811  			for p := s.pp.Text; p != nil; p = p.Link {
  6812  				if p.Pos.IsKnown() {
  6813  					allPos = allPos[:0]
  6814  					p.Ctxt.AllPos(p.Pos, func(pos src.Pos) { allPos = append(allPos, pos) })
  6815  					if inliningDiffers(allPos, allPosOld) {
  6816  						for _, pos := range allPos {
  6817  							fmt.Fprintf(fi, "# %s:%d\n", pos.Filename(), pos.Line())
  6818  						}
  6819  						allPos, allPosOld = allPosOld, allPos // swap, not copy, so that they do not share slice storage.
  6820  					}
  6821  				}
  6822  
  6823  				var s string
  6824  				if v, ok := progToValue[p]; ok {
  6825  					s = v.String()
  6826  				} else if b, ok := progToBlock[p]; ok {
  6827  					s = b.String()
  6828  				} else {
  6829  					s = "   " // most value and branch strings are 2-3 characters long
  6830  				}
  6831  				fmt.Fprintf(fi, " %-6s\t%.5d %s\t%s\n", s, p.Pc, ssa.StmtString(p.Pos), p.InstructionString())
  6832  			}
  6833  			fi.Close()
  6834  		}
  6835  	}
  6836  
  6837  	defframe(&s, e, f)
  6838  
  6839  	f.HTMLWriter.Close()
  6840  	f.HTMLWriter = nil
  6841  }
  6842  
  6843  func defframe(s *State, e *ssafn, f *ssa.Func) {
  6844  	pp := s.pp
  6845  
  6846  	s.maxarg = types.RoundUp(s.maxarg, e.stkalign)
  6847  	frame := s.maxarg + e.stksize
  6848  	if Arch.PadFrame != nil {
  6849  		frame = Arch.PadFrame(frame)
  6850  	}
  6851  
  6852  	// Fill in argument and frame size.
  6853  	pp.Text.To.Type = obj.TYPE_TEXTSIZE
  6854  	pp.Text.To.Val = int32(types.RoundUp(f.OwnAux.ArgWidth(), int64(types.RegSize)))
  6855  	pp.Text.To.Offset = frame
  6856  
  6857  	p := pp.Text
  6858  
  6859  	// Insert code to spill argument registers if the named slot may be partially
  6860  	// live. That is, the named slot is considered live by liveness analysis,
  6861  	// (because a part of it is live), but we may not spill all parts into the
  6862  	// slot. This can only happen with aggregate-typed arguments that are SSA-able
  6863  	// and not address-taken (for non-SSA-able or address-taken arguments we always
  6864  	// spill upfront).
  6865  	// Note: spilling is unnecessary in the -N/no-optimize case, since all values
  6866  	// will be considered non-SSAable and spilled up front.
  6867  	// TODO(register args) Make liveness more fine-grained to that partial spilling is okay.
  6868  	if f.OwnAux.ABIInfo().InRegistersUsed() != 0 && base.Flag.N == 0 {
  6869  		// First, see if it is already spilled before it may be live. Look for a spill
  6870  		// in the entry block up to the first safepoint.
  6871  		type nameOff struct {
  6872  			n   *ir.Name
  6873  			off int64
  6874  		}
  6875  		partLiveArgsSpilled := make(map[nameOff]bool)
  6876  		for _, v := range f.Entry.Values {
  6877  			if v.Op.IsCall() {
  6878  				break
  6879  			}
  6880  			if v.Op != ssa.OpStoreReg || v.Args[0].Op != ssa.OpArgIntReg {
  6881  				continue
  6882  			}
  6883  			n, off := ssa.AutoVar(v)
  6884  			if n.Class != ir.PPARAM || n.Addrtaken() || !ssa.CanSSA(n.Type()) || !s.partLiveArgs[n] {
  6885  				continue
  6886  			}
  6887  			partLiveArgsSpilled[nameOff{n, off}] = true
  6888  		}
  6889  
  6890  		// Then, insert code to spill registers if not already.
  6891  		for _, a := range f.OwnAux.ABIInfo().InParams() {
  6892  			n := a.Name
  6893  			if n == nil || n.Addrtaken() || !ssa.CanSSA(n.Type()) || !s.partLiveArgs[n] || len(a.Registers) <= 1 {
  6894  				continue
  6895  			}
  6896  			rts, offs := a.RegisterTypesAndOffsets()
  6897  			for i := range a.Registers {
  6898  				if !rts[i].HasPointers() {
  6899  					continue
  6900  				}
  6901  				if partLiveArgsSpilled[nameOff{n, offs[i]}] {
  6902  					continue // already spilled
  6903  				}
  6904  				reg := ssa.ObjRegForAbiReg(a.Registers[i], f.Config)
  6905  				p = Arch.SpillArgReg(pp, p, f, rts[i], reg, n, offs[i])
  6906  			}
  6907  		}
  6908  	}
  6909  
  6910  	// Insert code to zero ambiguously live variables so that the
  6911  	// garbage collector only sees initialized values when it
  6912  	// looks for pointers.
  6913  	var lo, hi int64
  6914  
  6915  	// Opaque state for backend to use. Current backends use it to
  6916  	// keep track of which helper registers have been zeroed.
  6917  	var state uint32
  6918  
  6919  	// Iterate through declarations. Autos are sorted in decreasing
  6920  	// frame offset order.
  6921  	for _, n := range e.curfn.Dcl {
  6922  		if !n.Needzero() {
  6923  			continue
  6924  		}
  6925  		if n.Class != ir.PAUTO {
  6926  			e.Fatalf(n.Pos(), "needzero class %d", n.Class)
  6927  		}
  6928  		if n.Type().Size()%int64(types.PtrSize) != 0 || n.FrameOffset()%int64(types.PtrSize) != 0 || n.Type().Size() == 0 {
  6929  			e.Fatalf(n.Pos(), "var %L has size %d offset %d", n, n.Type().Size(), n.Offset_)
  6930  		}
  6931  
  6932  		if lo != hi && n.FrameOffset()+n.Type().Size() >= lo-int64(2*types.RegSize) {
  6933  			// Merge with range we already have.
  6934  			lo = n.FrameOffset()
  6935  			continue
  6936  		}
  6937  
  6938  		// Zero old range
  6939  		p = Arch.ZeroRange(pp, p, frame+lo, hi-lo, &state)
  6940  
  6941  		// Set new range.
  6942  		lo = n.FrameOffset()
  6943  		hi = lo + n.Type().Size()
  6944  	}
  6945  
  6946  	// Zero final range.
  6947  	Arch.ZeroRange(pp, p, frame+lo, hi-lo, &state)
  6948  }
  6949  
  6950  // For generating consecutive jump instructions to model a specific branching
  6951  type IndexJump struct {
  6952  	Jump  obj.As
  6953  	Index int
  6954  }
  6955  
  6956  func (s *State) oneJump(b *ssa.Block, jump *IndexJump) {
  6957  	p := s.Br(jump.Jump, b.Succs[jump.Index].Block())
  6958  	p.Pos = b.Pos
  6959  }
  6960  
  6961  // CombJump generates combinational instructions (2 at present) for a block jump,
  6962  // thereby the behaviour of non-standard condition codes could be simulated
  6963  func (s *State) CombJump(b, next *ssa.Block, jumps *[2][2]IndexJump) {
  6964  	switch next {
  6965  	case b.Succs[0].Block():
  6966  		s.oneJump(b, &jumps[0][0])
  6967  		s.oneJump(b, &jumps[0][1])
  6968  	case b.Succs[1].Block():
  6969  		s.oneJump(b, &jumps[1][0])
  6970  		s.oneJump(b, &jumps[1][1])
  6971  	default:
  6972  		var q *obj.Prog
  6973  		if b.Likely != ssa.BranchUnlikely {
  6974  			s.oneJump(b, &jumps[1][0])
  6975  			s.oneJump(b, &jumps[1][1])
  6976  			q = s.Br(obj.AJMP, b.Succs[1].Block())
  6977  		} else {
  6978  			s.oneJump(b, &jumps[0][0])
  6979  			s.oneJump(b, &jumps[0][1])
  6980  			q = s.Br(obj.AJMP, b.Succs[0].Block())
  6981  		}
  6982  		q.Pos = b.Pos
  6983  	}
  6984  }
  6985  
  6986  // AddAux adds the offset in the aux fields (AuxInt and Aux) of v to a.
  6987  func AddAux(a *obj.Addr, v *ssa.Value) {
  6988  	AddAux2(a, v, v.AuxInt)
  6989  }
  6990  func AddAux2(a *obj.Addr, v *ssa.Value, offset int64) {
  6991  	if a.Type != obj.TYPE_MEM && a.Type != obj.TYPE_ADDR {
  6992  		v.Fatalf("bad AddAux addr %v", a)
  6993  	}
  6994  	// add integer offset
  6995  	a.Offset += offset
  6996  
  6997  	// If no additional symbol offset, we're done.
  6998  	if v.Aux == nil {
  6999  		return
  7000  	}
  7001  	// Add symbol's offset from its base register.
  7002  	switch n := v.Aux.(type) {
  7003  	case *ssa.AuxCall:
  7004  		a.Name = obj.NAME_EXTERN
  7005  		a.Sym = n.Fn
  7006  	case *obj.LSym:
  7007  		a.Name = obj.NAME_EXTERN
  7008  		a.Sym = n
  7009  	case *ir.Name:
  7010  		if n.Class == ir.PPARAM || (n.Class == ir.PPARAMOUT && !n.IsOutputParamInRegisters()) {
  7011  			a.Name = obj.NAME_PARAM
  7012  		} else {
  7013  			a.Name = obj.NAME_AUTO
  7014  		}
  7015  		a.Sym = n.Linksym()
  7016  		a.Offset += n.FrameOffset()
  7017  	default:
  7018  		v.Fatalf("aux in %s not implemented %#v", v, v.Aux)
  7019  	}
  7020  }
  7021  
  7022  // extendIndex extends v to a full int width.
  7023  // panic with the given kind if v does not fit in an int (only on 32-bit archs).
  7024  func (s *state) extendIndex(idx, len *ssa.Value, kind ssa.BoundsKind, bounded bool) *ssa.Value {
  7025  	size := idx.Type.Size()
  7026  	if size == s.config.PtrSize {
  7027  		return idx
  7028  	}
  7029  	if size > s.config.PtrSize {
  7030  		// truncate 64-bit indexes on 32-bit pointer archs. Test the
  7031  		// high word and branch to out-of-bounds failure if it is not 0.
  7032  		var lo *ssa.Value
  7033  		if idx.Type.IsSigned() {
  7034  			lo = s.newValue1(ssa.OpInt64Lo, types.Types[types.TINT], idx)
  7035  		} else {
  7036  			lo = s.newValue1(ssa.OpInt64Lo, types.Types[types.TUINT], idx)
  7037  		}
  7038  		if bounded || base.Flag.B != 0 {
  7039  			return lo
  7040  		}
  7041  		bNext := s.f.NewBlock(ssa.BlockPlain)
  7042  		bPanic := s.f.NewBlock(ssa.BlockExit)
  7043  		hi := s.newValue1(ssa.OpInt64Hi, types.Types[types.TUINT32], idx)
  7044  		cmp := s.newValue2(ssa.OpEq32, types.Types[types.TBOOL], hi, s.constInt32(types.Types[types.TUINT32], 0))
  7045  		if !idx.Type.IsSigned() {
  7046  			switch kind {
  7047  			case ssa.BoundsIndex:
  7048  				kind = ssa.BoundsIndexU
  7049  			case ssa.BoundsSliceAlen:
  7050  				kind = ssa.BoundsSliceAlenU
  7051  			case ssa.BoundsSliceAcap:
  7052  				kind = ssa.BoundsSliceAcapU
  7053  			case ssa.BoundsSliceB:
  7054  				kind = ssa.BoundsSliceBU
  7055  			case ssa.BoundsSlice3Alen:
  7056  				kind = ssa.BoundsSlice3AlenU
  7057  			case ssa.BoundsSlice3Acap:
  7058  				kind = ssa.BoundsSlice3AcapU
  7059  			case ssa.BoundsSlice3B:
  7060  				kind = ssa.BoundsSlice3BU
  7061  			case ssa.BoundsSlice3C:
  7062  				kind = ssa.BoundsSlice3CU
  7063  			}
  7064  		}
  7065  		b := s.endBlock()
  7066  		b.Kind = ssa.BlockIf
  7067  		b.SetControl(cmp)
  7068  		b.Likely = ssa.BranchLikely
  7069  		b.AddEdgeTo(bNext)
  7070  		b.AddEdgeTo(bPanic)
  7071  
  7072  		s.startBlock(bPanic)
  7073  		mem := s.newValue4I(ssa.OpPanicExtend, types.TypeMem, int64(kind), hi, lo, len, s.mem())
  7074  		s.endBlock().SetControl(mem)
  7075  		s.startBlock(bNext)
  7076  
  7077  		return lo
  7078  	}
  7079  
  7080  	// Extend value to the required size
  7081  	var op ssa.Op
  7082  	if idx.Type.IsSigned() {
  7083  		switch 10*size + s.config.PtrSize {
  7084  		case 14:
  7085  			op = ssa.OpSignExt8to32
  7086  		case 18:
  7087  			op = ssa.OpSignExt8to64
  7088  		case 24:
  7089  			op = ssa.OpSignExt16to32
  7090  		case 28:
  7091  			op = ssa.OpSignExt16to64
  7092  		case 48:
  7093  			op = ssa.OpSignExt32to64
  7094  		default:
  7095  			s.Fatalf("bad signed index extension %s", idx.Type)
  7096  		}
  7097  	} else {
  7098  		switch 10*size + s.config.PtrSize {
  7099  		case 14:
  7100  			op = ssa.OpZeroExt8to32
  7101  		case 18:
  7102  			op = ssa.OpZeroExt8to64
  7103  		case 24:
  7104  			op = ssa.OpZeroExt16to32
  7105  		case 28:
  7106  			op = ssa.OpZeroExt16to64
  7107  		case 48:
  7108  			op = ssa.OpZeroExt32to64
  7109  		default:
  7110  			s.Fatalf("bad unsigned index extension %s", idx.Type)
  7111  		}
  7112  	}
  7113  	return s.newValue1(op, types.Types[types.TINT], idx)
  7114  }
  7115  
  7116  // CheckLoweredPhi checks that regalloc and stackalloc correctly handled phi values.
  7117  // Called during ssaGenValue.
  7118  func CheckLoweredPhi(v *ssa.Value) {
  7119  	if v.Op != ssa.OpPhi {
  7120  		v.Fatalf("CheckLoweredPhi called with non-phi value: %v", v.LongString())
  7121  	}
  7122  	if v.Type.IsMemory() {
  7123  		return
  7124  	}
  7125  	f := v.Block.Func
  7126  	loc := f.RegAlloc[v.ID]
  7127  	for _, a := range v.Args {
  7128  		if aloc := f.RegAlloc[a.ID]; aloc != loc { // TODO: .Equal() instead?
  7129  			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)
  7130  		}
  7131  	}
  7132  }
  7133  
  7134  // CheckLoweredGetClosurePtr checks that v is the first instruction in the function's entry block,
  7135  // except for incoming in-register arguments.
  7136  // The output of LoweredGetClosurePtr is generally hardwired to the correct register.
  7137  // That register contains the closure pointer on closure entry.
  7138  func CheckLoweredGetClosurePtr(v *ssa.Value) {
  7139  	entry := v.Block.Func.Entry
  7140  	if entry != v.Block {
  7141  		base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
  7142  	}
  7143  	for _, w := range entry.Values {
  7144  		if w == v {
  7145  			break
  7146  		}
  7147  		switch w.Op {
  7148  		case ssa.OpArgIntReg, ssa.OpArgFloatReg:
  7149  			// okay
  7150  		default:
  7151  			base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
  7152  		}
  7153  	}
  7154  }
  7155  
  7156  // CheckArgReg ensures that v is in the function's entry block.
  7157  func CheckArgReg(v *ssa.Value) {
  7158  	entry := v.Block.Func.Entry
  7159  	if entry != v.Block {
  7160  		base.Fatalf("in %s, badly placed ArgIReg or ArgFReg: %v %v", v.Block.Func.Name, v.Block, v)
  7161  	}
  7162  }
  7163  
  7164  func AddrAuto(a *obj.Addr, v *ssa.Value) {
  7165  	n, off := ssa.AutoVar(v)
  7166  	a.Type = obj.TYPE_MEM
  7167  	a.Sym = n.Linksym()
  7168  	a.Reg = int16(Arch.REGSP)
  7169  	a.Offset = n.FrameOffset() + off
  7170  	if n.Class == ir.PPARAM || (n.Class == ir.PPARAMOUT && !n.IsOutputParamInRegisters()) {
  7171  		a.Name = obj.NAME_PARAM
  7172  	} else {
  7173  		a.Name = obj.NAME_AUTO
  7174  	}
  7175  }
  7176  
  7177  // Call returns a new CALL instruction for the SSA value v.
  7178  // It uses PrepareCall to prepare the call.
  7179  func (s *State) Call(v *ssa.Value) *obj.Prog {
  7180  	pPosIsStmt := s.pp.Pos.IsStmt() // The statement-ness fo the call comes from ssaGenState
  7181  	s.PrepareCall(v)
  7182  
  7183  	p := s.Prog(obj.ACALL)
  7184  	if pPosIsStmt == src.PosIsStmt {
  7185  		p.Pos = v.Pos.WithIsStmt()
  7186  	} else {
  7187  		p.Pos = v.Pos.WithNotStmt()
  7188  	}
  7189  	if sym, ok := v.Aux.(*ssa.AuxCall); ok && sym.Fn != nil {
  7190  		p.To.Type = obj.TYPE_MEM
  7191  		p.To.Name = obj.NAME_EXTERN
  7192  		p.To.Sym = sym.Fn
  7193  	} else {
  7194  		// TODO(mdempsky): Can these differences be eliminated?
  7195  		switch Arch.LinkArch.Family {
  7196  		case sys.AMD64, sys.I386, sys.PPC64, sys.RISCV64, sys.S390X, sys.Wasm:
  7197  			p.To.Type = obj.TYPE_REG
  7198  		case sys.ARM, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64:
  7199  			p.To.Type = obj.TYPE_MEM
  7200  		default:
  7201  			base.Fatalf("unknown indirect call family")
  7202  		}
  7203  		p.To.Reg = v.Args[0].Reg()
  7204  	}
  7205  	return p
  7206  }
  7207  
  7208  // TailCall returns a new tail call instruction for the SSA value v.
  7209  // It is like Call, but for a tail call.
  7210  func (s *State) TailCall(v *ssa.Value) *obj.Prog {
  7211  	p := s.Call(v)
  7212  	p.As = obj.ARET
  7213  	return p
  7214  }
  7215  
  7216  // PrepareCall prepares to emit a CALL instruction for v and does call-related bookkeeping.
  7217  // It must be called immediately before emitting the actual CALL instruction,
  7218  // since it emits PCDATA for the stack map at the call (calls are safe points).
  7219  func (s *State) PrepareCall(v *ssa.Value) {
  7220  	idx := s.livenessMap.Get(v)
  7221  	if !idx.StackMapValid() {
  7222  		// See Liveness.hasStackMap.
  7223  		if sym, ok := v.Aux.(*ssa.AuxCall); !ok || !(sym.Fn == ir.Syms.WBZero || sym.Fn == ir.Syms.WBMove) {
  7224  			base.Fatalf("missing stack map index for %v", v.LongString())
  7225  		}
  7226  	}
  7227  
  7228  	call, ok := v.Aux.(*ssa.AuxCall)
  7229  
  7230  	if ok {
  7231  		// Record call graph information for nowritebarrierrec
  7232  		// analysis.
  7233  		if nowritebarrierrecCheck != nil {
  7234  			nowritebarrierrecCheck.recordCall(s.pp.CurFunc, call.Fn, v.Pos)
  7235  		}
  7236  	}
  7237  
  7238  	if s.maxarg < v.AuxInt {
  7239  		s.maxarg = v.AuxInt
  7240  	}
  7241  }
  7242  
  7243  // UseArgs records the fact that an instruction needs a certain amount of
  7244  // callee args space for its use.
  7245  func (s *State) UseArgs(n int64) {
  7246  	if s.maxarg < n {
  7247  		s.maxarg = n
  7248  	}
  7249  }
  7250  
  7251  // fieldIdx finds the index of the field referred to by the ODOT node n.
  7252  func fieldIdx(n *ir.SelectorExpr) int {
  7253  	t := n.X.Type()
  7254  	if !t.IsStruct() {
  7255  		panic("ODOT's LHS is not a struct")
  7256  	}
  7257  
  7258  	for i, f := range t.Fields() {
  7259  		if f.Sym == n.Sel {
  7260  			if f.Offset != n.Offset() {
  7261  				panic("field offset doesn't match")
  7262  			}
  7263  			return i
  7264  		}
  7265  	}
  7266  	panic(fmt.Sprintf("can't find field in expr %v\n", n))
  7267  
  7268  	// TODO: keep the result of this function somewhere in the ODOT Node
  7269  	// so we don't have to recompute it each time we need it.
  7270  }
  7271  
  7272  // ssafn holds frontend information about a function that the backend is processing.
  7273  // It also exports a bunch of compiler services for the ssa backend.
  7274  type ssafn struct {
  7275  	curfn      *ir.Func
  7276  	strings    map[string]*obj.LSym // map from constant string to data symbols
  7277  	stksize    int64                // stack size for current frame
  7278  	stkptrsize int64                // prefix of stack containing pointers
  7279  
  7280  	// alignment for current frame.
  7281  	// NOTE: when stkalign > PtrSize, currently this only ensures the offsets of
  7282  	// objects in the stack frame are aligned. The stack pointer is still aligned
  7283  	// only PtrSize.
  7284  	stkalign int64
  7285  
  7286  	log bool // print ssa debug to the stdout
  7287  }
  7288  
  7289  // StringData returns a symbol which
  7290  // is the data component of a global string constant containing s.
  7291  func (e *ssafn) StringData(s string) *obj.LSym {
  7292  	if aux, ok := e.strings[s]; ok {
  7293  		return aux
  7294  	}
  7295  	if e.strings == nil {
  7296  		e.strings = make(map[string]*obj.LSym)
  7297  	}
  7298  	data := staticdata.StringSym(e.curfn.Pos(), s)
  7299  	e.strings[s] = data
  7300  	return data
  7301  }
  7302  
  7303  // SplitSlot returns a slot representing the data of parent starting at offset.
  7304  func (e *ssafn) SplitSlot(parent *ssa.LocalSlot, suffix string, offset int64, t *types.Type) ssa.LocalSlot {
  7305  	node := parent.N
  7306  
  7307  	if node.Class != ir.PAUTO || node.Addrtaken() {
  7308  		// addressed things and non-autos retain their parents (i.e., cannot truly be split)
  7309  		return ssa.LocalSlot{N: node, Type: t, Off: parent.Off + offset}
  7310  	}
  7311  
  7312  	sym := &types.Sym{Name: node.Sym().Name + suffix, Pkg: types.LocalPkg}
  7313  	n := e.curfn.NewLocal(parent.N.Pos(), sym, t)
  7314  	n.SetUsed(true)
  7315  	n.SetEsc(ir.EscNever)
  7316  	types.CalcSize(t)
  7317  	return ssa.LocalSlot{N: n, Type: t, Off: 0, SplitOf: parent, SplitOffset: offset}
  7318  }
  7319  
  7320  // Logf logs a message from the compiler.
  7321  func (e *ssafn) Logf(msg string, args ...interface{}) {
  7322  	if e.log {
  7323  		fmt.Printf(msg, args...)
  7324  	}
  7325  }
  7326  
  7327  func (e *ssafn) Log() bool {
  7328  	return e.log
  7329  }
  7330  
  7331  // Fatalf reports a compiler error and exits.
  7332  func (e *ssafn) Fatalf(pos src.XPos, msg string, args ...interface{}) {
  7333  	base.Pos = pos
  7334  	nargs := append([]interface{}{ir.FuncName(e.curfn)}, args...)
  7335  	base.Fatalf("'%s': "+msg, nargs...)
  7336  }
  7337  
  7338  // Warnl reports a "warning", which is usually flag-triggered
  7339  // logging output for the benefit of tests.
  7340  func (e *ssafn) Warnl(pos src.XPos, fmt_ string, args ...interface{}) {
  7341  	base.WarnfAt(pos, fmt_, args...)
  7342  }
  7343  
  7344  func (e *ssafn) Debug_checknil() bool {
  7345  	return base.Debug.Nil != 0
  7346  }
  7347  
  7348  func (e *ssafn) UseWriteBarrier() bool {
  7349  	return base.Flag.WB
  7350  }
  7351  
  7352  func (e *ssafn) Syslook(name string) *obj.LSym {
  7353  	switch name {
  7354  	case "goschedguarded":
  7355  		return ir.Syms.Goschedguarded
  7356  	case "writeBarrier":
  7357  		return ir.Syms.WriteBarrier
  7358  	case "wbZero":
  7359  		return ir.Syms.WBZero
  7360  	case "wbMove":
  7361  		return ir.Syms.WBMove
  7362  	case "cgoCheckMemmove":
  7363  		return ir.Syms.CgoCheckMemmove
  7364  	case "cgoCheckPtrWrite":
  7365  		return ir.Syms.CgoCheckPtrWrite
  7366  	}
  7367  	e.Fatalf(src.NoXPos, "unknown Syslook func %v", name)
  7368  	return nil
  7369  }
  7370  
  7371  func (e *ssafn) Func() *ir.Func {
  7372  	return e.curfn
  7373  }
  7374  
  7375  func clobberBase(n ir.Node) ir.Node {
  7376  	if n.Op() == ir.ODOT {
  7377  		n := n.(*ir.SelectorExpr)
  7378  		if n.X.Type().NumFields() == 1 {
  7379  			return clobberBase(n.X)
  7380  		}
  7381  	}
  7382  	if n.Op() == ir.OINDEX {
  7383  		n := n.(*ir.IndexExpr)
  7384  		if n.X.Type().IsArray() && n.X.Type().NumElem() == 1 {
  7385  			return clobberBase(n.X)
  7386  		}
  7387  	}
  7388  	return n
  7389  }
  7390  
  7391  // callTargetLSym returns the correct LSym to call 'callee' using its ABI.
  7392  func callTargetLSym(callee *ir.Name) *obj.LSym {
  7393  	if callee.Func == nil {
  7394  		// TODO(austin): This happens in case of interface method I.M from imported package.
  7395  		// It's ABIInternal, and would be better if callee.Func was never nil and we didn't
  7396  		// need this case.
  7397  		return callee.Linksym()
  7398  	}
  7399  
  7400  	return callee.LinksymABI(callee.Func.ABI)
  7401  }
  7402  
  7403  // deferStructFnField is the field index of _defer.fn.
  7404  const deferStructFnField = 4
  7405  
  7406  var deferType *types.Type
  7407  
  7408  // deferstruct returns a type interchangeable with runtime._defer.
  7409  // Make sure this stays in sync with runtime/runtime2.go:_defer.
  7410  func deferstruct() *types.Type {
  7411  	if deferType != nil {
  7412  		return deferType
  7413  	}
  7414  
  7415  	makefield := func(name string, t *types.Type) *types.Field {
  7416  		sym := (*types.Pkg)(nil).Lookup(name)
  7417  		return types.NewField(src.NoXPos, sym, t)
  7418  	}
  7419  
  7420  	fields := []*types.Field{
  7421  		makefield("heap", types.Types[types.TBOOL]),
  7422  		makefield("rangefunc", types.Types[types.TBOOL]),
  7423  		makefield("sp", types.Types[types.TUINTPTR]),
  7424  		makefield("pc", types.Types[types.TUINTPTR]),
  7425  		// Note: the types here don't really matter. Defer structures
  7426  		// are always scanned explicitly during stack copying and GC,
  7427  		// so we make them uintptr type even though they are real pointers.
  7428  		makefield("fn", types.Types[types.TUINTPTR]),
  7429  		makefield("link", types.Types[types.TUINTPTR]),
  7430  		makefield("head", types.Types[types.TUINTPTR]),
  7431  	}
  7432  	if name := fields[deferStructFnField].Sym.Name; name != "fn" {
  7433  		base.Fatalf("deferStructFnField is %q, not fn", name)
  7434  	}
  7435  
  7436  	n := ir.NewDeclNameAt(src.NoXPos, ir.OTYPE, ir.Pkgs.Runtime.Lookup("_defer"))
  7437  	typ := types.NewNamed(n)
  7438  	n.SetType(typ)
  7439  	n.SetTypecheck(1)
  7440  
  7441  	// build struct holding the above fields
  7442  	typ.SetUnderlying(types.NewStruct(fields))
  7443  	types.CalcStructSize(typ)
  7444  
  7445  	deferType = typ
  7446  	return typ
  7447  }
  7448  
  7449  // SpillSlotAddr uses LocalSlot information to initialize an obj.Addr
  7450  // The resulting addr is used in a non-standard context -- in the prologue
  7451  // of a function, before the frame has been constructed, so the standard
  7452  // addressing for the parameters will be wrong.
  7453  func SpillSlotAddr(spill ssa.Spill, baseReg int16, extraOffset int64) obj.Addr {
  7454  	return obj.Addr{
  7455  		Name:   obj.NAME_NONE,
  7456  		Type:   obj.TYPE_MEM,
  7457  		Reg:    baseReg,
  7458  		Offset: spill.Offset + extraOffset,
  7459  	}
  7460  }
  7461  
  7462  var (
  7463  	BoundsCheckFunc [ssa.BoundsKindCount]*obj.LSym
  7464  	ExtendCheckFunc [ssa.BoundsKindCount]*obj.LSym
  7465  )
  7466