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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package gc
import (
var ssaConfig *ssa.Config
var ssaCaches []ssa.Cache
var ssaDump string // early copy of $GOSSAFUNC; the func name to dump output for
var ssaDir string // optional destination for ssa dump file
var ssaDumpStdout bool // whether to dump to stdout
var ssaDumpCFG string // generate CFGs for these phases
const ssaDumpFile = "ssa.html"
// The max number of defers in a function using open-coded defers. We enforce this
// limit because the deferBits bitmask is currently a single byte (to minimize code size)
const maxOpenDefers = 8
// ssaDumpInlined holds all inlined functions when ssaDump contains a function name.
var ssaDumpInlined []*Node
func initssaconfig() {
types_ := ssa.NewTypes()
if thearch.SoftFloat {
// Generate a few pointer types that are uncommon in the frontend but common in the backend.
// Caching is disabled in the backend, so generating these here avoids allocations.
_ = types.NewPtr(types.Types[TINTER]) // *interface{}
_ = types.NewPtr(types.NewPtr(types.Types[TSTRING])) // **string
_ = types.NewPtr(types.NewSlice(types.Types[TINTER])) // *[]interface{}
_ = types.NewPtr(types.NewPtr(types.Bytetype)) // **byte
_ = types.NewPtr(types.NewSlice(types.Bytetype)) // *[]byte
_ = types.NewPtr(types.NewSlice(types.Types[TSTRING])) // *[]string
_ = types.NewPtr(types.NewPtr(types.NewPtr(types.Types[TUINT8]))) // ***uint8
_ = types.NewPtr(types.Types[TINT16]) // *int16
_ = types.NewPtr(types.Types[TINT64]) // *int64
_ = types.NewPtr(types.Errortype) // *error
types.NewPtrCacheEnabled = false
ssaConfig = ssa.NewConfig(thearch.LinkArch.Name, *types_, Ctxt, Debug.N == 0)
ssaConfig.SoftFloat = thearch.SoftFloat
ssaConfig.Race = flag_race
ssaCaches = make([]ssa.Cache, nBackendWorkers)
// Set up some runtime functions we'll need to call.
assertE2I = sysfunc("assertE2I")
assertE2I2 = sysfunc("assertE2I2")
assertI2I = sysfunc("assertI2I")
assertI2I2 = sysfunc("assertI2I2")
deferproc = sysfunc("deferproc")
deferprocStack = sysfunc("deferprocStack")
Deferreturn = sysfunc("deferreturn")
Duffcopy = sysfunc("duffcopy")
Duffzero = sysfunc("duffzero")
gcWriteBarrier = sysfunc("gcWriteBarrier")
goschedguarded = sysfunc("goschedguarded")
growslice = sysfunc("growslice")
msanread = sysfunc("msanread")
msanwrite = sysfunc("msanwrite")
msanmove = sysfunc("msanmove")
newobject = sysfunc("newobject")
newproc = sysfunc("newproc")
panicdivide = sysfunc("panicdivide")
panicdottypeE = sysfunc("panicdottypeE")
panicdottypeI = sysfunc("panicdottypeI")
panicnildottype = sysfunc("panicnildottype")
panicoverflow = sysfunc("panicoverflow")
panicshift = sysfunc("panicshift")
raceread = sysfunc("raceread")
racereadrange = sysfunc("racereadrange")
racewrite = sysfunc("racewrite")
racewriterange = sysfunc("racewriterange")
x86HasPOPCNT = sysvar("x86HasPOPCNT") // bool
x86HasSSE41 = sysvar("x86HasSSE41") // bool
x86HasFMA = sysvar("x86HasFMA") // bool
armHasVFPv4 = sysvar("armHasVFPv4") // bool
arm64HasATOMICS = sysvar("arm64HasATOMICS") // bool
typedmemclr = sysfunc("typedmemclr")
typedmemmove = sysfunc("typedmemmove")
Udiv = sysvar("udiv") // asm func with special ABI
writeBarrier = sysvar("writeBarrier") // struct { bool; ... }
zerobaseSym = sysvar("zerobase")
// asm funcs with special ABI
if thearch.LinkArch.Name == "amd64" {
GCWriteBarrierReg = map[int16]*obj.LSym{
x86.REG_AX: sysfunc("gcWriteBarrier"),
x86.REG_CX: sysfunc("gcWriteBarrierCX"),
x86.REG_DX: sysfunc("gcWriteBarrierDX"),
x86.REG_BX: sysfunc("gcWriteBarrierBX"),
x86.REG_BP: sysfunc("gcWriteBarrierBP"),
x86.REG_SI: sysfunc("gcWriteBarrierSI"),
x86.REG_R8: sysfunc("gcWriteBarrierR8"),
x86.REG_R9: sysfunc("gcWriteBarrierR9"),
if thearch.LinkArch.Family == sys.Wasm {
BoundsCheckFunc[ssa.BoundsIndex] = sysfunc("goPanicIndex")
BoundsCheckFunc[ssa.BoundsIndexU] = sysfunc("goPanicIndexU")
BoundsCheckFunc[ssa.BoundsSliceAlen] = sysfunc("goPanicSliceAlen")
BoundsCheckFunc[ssa.BoundsSliceAlenU] = sysfunc("goPanicSliceAlenU")
BoundsCheckFunc[ssa.BoundsSliceAcap] = sysfunc("goPanicSliceAcap")
BoundsCheckFunc[ssa.BoundsSliceAcapU] = sysfunc("goPanicSliceAcapU")
BoundsCheckFunc[ssa.BoundsSliceB] = sysfunc("goPanicSliceB")
BoundsCheckFunc[ssa.BoundsSliceBU] = sysfunc("goPanicSliceBU")
BoundsCheckFunc[ssa.BoundsSlice3Alen] = sysfunc("goPanicSlice3Alen")
BoundsCheckFunc[ssa.BoundsSlice3AlenU] = sysfunc("goPanicSlice3AlenU")
BoundsCheckFunc[ssa.BoundsSlice3Acap] = sysfunc("goPanicSlice3Acap")
BoundsCheckFunc[ssa.BoundsSlice3AcapU] = sysfunc("goPanicSlice3AcapU")
BoundsCheckFunc[ssa.BoundsSlice3B] = sysfunc("goPanicSlice3B")
BoundsCheckFunc[ssa.BoundsSlice3BU] = sysfunc("goPanicSlice3BU")
BoundsCheckFunc[ssa.BoundsSlice3C] = sysfunc("goPanicSlice3C")
BoundsCheckFunc[ssa.BoundsSlice3CU] = sysfunc("goPanicSlice3CU")
} else {
BoundsCheckFunc[ssa.BoundsIndex] = sysfunc("panicIndex")
BoundsCheckFunc[ssa.BoundsIndexU] = sysfunc("panicIndexU")
BoundsCheckFunc[ssa.BoundsSliceAlen] = sysfunc("panicSliceAlen")
BoundsCheckFunc[ssa.BoundsSliceAlenU] = sysfunc("panicSliceAlenU")
BoundsCheckFunc[ssa.BoundsSliceAcap] = sysfunc("panicSliceAcap")
BoundsCheckFunc[ssa.BoundsSliceAcapU] = sysfunc("panicSliceAcapU")
BoundsCheckFunc[ssa.BoundsSliceB] = sysfunc("panicSliceB")
BoundsCheckFunc[ssa.BoundsSliceBU] = sysfunc("panicSliceBU")
BoundsCheckFunc[ssa.BoundsSlice3Alen] = sysfunc("panicSlice3Alen")
BoundsCheckFunc[ssa.BoundsSlice3AlenU] = sysfunc("panicSlice3AlenU")
BoundsCheckFunc[ssa.BoundsSlice3Acap] = sysfunc("panicSlice3Acap")
BoundsCheckFunc[ssa.BoundsSlice3AcapU] = sysfunc("panicSlice3AcapU")
BoundsCheckFunc[ssa.BoundsSlice3B] = sysfunc("panicSlice3B")
BoundsCheckFunc[ssa.BoundsSlice3BU] = sysfunc("panicSlice3BU")
BoundsCheckFunc[ssa.BoundsSlice3C] = sysfunc("panicSlice3C")
BoundsCheckFunc[ssa.BoundsSlice3CU] = sysfunc("panicSlice3CU")
if thearch.LinkArch.PtrSize == 4 {
ExtendCheckFunc[ssa.BoundsIndex] = sysvar("panicExtendIndex")
ExtendCheckFunc[ssa.BoundsIndexU] = sysvar("panicExtendIndexU")
ExtendCheckFunc[ssa.BoundsSliceAlen] = sysvar("panicExtendSliceAlen")
ExtendCheckFunc[ssa.BoundsSliceAlenU] = sysvar("panicExtendSliceAlenU")
ExtendCheckFunc[ssa.BoundsSliceAcap] = sysvar("panicExtendSliceAcap")
ExtendCheckFunc[ssa.BoundsSliceAcapU] = sysvar("panicExtendSliceAcapU")
ExtendCheckFunc[ssa.BoundsSliceB] = sysvar("panicExtendSliceB")
ExtendCheckFunc[ssa.BoundsSliceBU] = sysvar("panicExtendSliceBU")
ExtendCheckFunc[ssa.BoundsSlice3Alen] = sysvar("panicExtendSlice3Alen")
ExtendCheckFunc[ssa.BoundsSlice3AlenU] = sysvar("panicExtendSlice3AlenU")
ExtendCheckFunc[ssa.BoundsSlice3Acap] = sysvar("panicExtendSlice3Acap")
ExtendCheckFunc[ssa.BoundsSlice3AcapU] = sysvar("panicExtendSlice3AcapU")
ExtendCheckFunc[ssa.BoundsSlice3B] = sysvar("panicExtendSlice3B")
ExtendCheckFunc[ssa.BoundsSlice3BU] = sysvar("panicExtendSlice3BU")
ExtendCheckFunc[ssa.BoundsSlice3C] = sysvar("panicExtendSlice3C")
ExtendCheckFunc[ssa.BoundsSlice3CU] = sysvar("panicExtendSlice3CU")
// Wasm (all asm funcs with special ABIs)
WasmMove = sysvar("wasmMove")
WasmZero = sysvar("wasmZero")
WasmDiv = sysvar("wasmDiv")
WasmTruncS = sysvar("wasmTruncS")
WasmTruncU = sysvar("wasmTruncU")
SigPanic = sysfunc("sigpanic")
// getParam returns the Field of ith param of node n (which is a
// function/method/interface call), where the receiver of a method call is
// considered as the 0th parameter. This does not include the receiver of an
// interface call.
func getParam(n *Node, i int) *types.Field {
t := n.Left.Type
if n.Op == OCALLMETH {
if i == 0 {
return t.Recv()
return t.Params().Field(i - 1)
return t.Params().Field(i)
// dvarint writes a varint v to the funcdata in symbol x and returns the new offset
func dvarint(x *obj.LSym, off int, v int64) int {
if v < 0 || v > 1e9 {
panic(fmt.Sprintf("dvarint: bad offset for funcdata - %v", v))
if v < 1<<7 {
return duint8(x, off, uint8(v))
off = duint8(x, off, uint8((v&127)|128))
if v < 1<<14 {
return duint8(x, off, uint8(v>>7))
off = duint8(x, off, uint8(((v>>7)&127)|128))
if v < 1<<21 {
return duint8(x, off, uint8(v>>14))
off = duint8(x, off, uint8(((v>>14)&127)|128))
if v < 1<<28 {
return duint8(x, off, uint8(v>>21))
off = duint8(x, off, uint8(((v>>21)&127)|128))
return duint8(x, off, uint8(v>>28))
// emitOpenDeferInfo emits FUNCDATA information about the defers in a function
// that is using open-coded defers. This funcdata is used to determine the active
// defers in a function and execute those defers during panic processing.
// The funcdata is all encoded in varints (since values will almost always be less than
// 128, but stack offsets could potentially be up to 2Gbyte). All "locations" (offsets)
// for stack variables are specified as the number of bytes below varp (pointer to the
// top of the local variables) for their starting address. The format is:
// - Max total argument size among all the defers
// - Offset of the deferBits variable
// - Number of defers in the function
// - Information about each defer call, in reverse order of appearance in the function:
// - Total argument size of the call
// - Offset of the closure value to call
// - Number of arguments (including interface receiver or method receiver as first arg)
// - Information about each argument
// - Offset of the stored defer argument in this function's frame
// - Size of the argument
// - Offset of where argument should be placed in the args frame when making call
func (s *state) emitOpenDeferInfo() {
x := Ctxt.Lookup(s.curfn.Func.lsym.Name + ".opendefer")
s.curfn.Func.lsym.Func().OpenCodedDeferInfo = x
off := 0
// Compute maxargsize (max size of arguments for all defers)
// first, so we can output it first to the funcdata
var maxargsize int64
for i := len(s.openDefers) - 1; i >= 0; i-- {
r := s.openDefers[i]
argsize := r.n.Left.Type.ArgWidth()
if argsize > maxargsize {
maxargsize = argsize
off = dvarint(x, off, maxargsize)
off = dvarint(x, off, -s.deferBitsTemp.Xoffset)
off = dvarint(x, off, int64(len(s.openDefers)))
// Write in reverse-order, for ease of running in that order at runtime
for i := len(s.openDefers) - 1; i >= 0; i-- {
r := s.openDefers[i]
off = dvarint(x, off, r.n.Left.Type.ArgWidth())
off = dvarint(x, off, -r.closureNode.Xoffset)
numArgs := len(r.argNodes)
if r.rcvrNode != nil {
// If there's an interface receiver, treat/place it as the first
// arg. (If there is a method receiver, it's already included as
// first arg in r.argNodes.)
off = dvarint(x, off, int64(numArgs))
if r.rcvrNode != nil {
off = dvarint(x, off, -r.rcvrNode.Xoffset)
off = dvarint(x, off, s.config.PtrSize)
off = dvarint(x, off, 0)
for j, arg := range r.argNodes {
f := getParam(r.n, j)
off = dvarint(x, off, -arg.Xoffset)
off = dvarint(x, off, f.Type.Size())
off = dvarint(x, off, f.Offset)
// buildssa builds an SSA function for fn.
// worker indicates which of the backend workers is doing the processing.
func buildssa(fn *Node, worker int) *ssa.Func {
name := fn.funcname()
printssa := false
if ssaDump != "" { // match either a simple name e.g. "(*Reader).Reset", or a e.g. "compress/gzip.(*Reader).Reset"
printssa = name == ssaDump || myimportpath+"."+name == ssaDump
var astBuf *bytes.Buffer
if printssa {
astBuf = &bytes.Buffer{}
fdumplist(astBuf, "buildssa-enter", fn.Func.Enter)
fdumplist(astBuf, "buildssa-body", fn.Nbody)
fdumplist(astBuf, "buildssa-exit", fn.Func.Exit)
if ssaDumpStdout {
fmt.Println("generating SSA for", name)
var s state
defer s.popLine()
s.hasdefer = fn.Func.HasDefer()
if fn.Func.Pragma&CgoUnsafeArgs != 0 {
s.cgoUnsafeArgs = true
fe := ssafn{
curfn: fn,
log: printssa && ssaDumpStdout,
s.curfn = fn
s.f = ssa.NewFunc(&fe)
s.config = ssaConfig
s.f.Type = fn.Type
s.f.Config = ssaConfig
s.f.Cache = &ssaCaches[worker]
s.f.Name = name
s.f.DebugTest = s.f.DebugHashMatch("GOSSAHASH")
s.f.PrintOrHtmlSSA = printssa
if fn.Func.Pragma&Nosplit != 0 {
s.f.NoSplit = true
s.panics = map[funcLine]*ssa.Block{}
s.softFloat = s.config.SoftFloat
// Allocate starting block
s.f.Entry = s.f.NewBlock(ssa.BlockPlain)
s.f.Entry.Pos = fn.Pos
if printssa {
ssaDF := ssaDumpFile
if ssaDir != "" {
ssaDF = filepath.Join(ssaDir, myimportpath+"."+name+".html")
ssaD := filepath.Dir(ssaDF)
os.MkdirAll(ssaD, 0755)
s.f.HTMLWriter = ssa.NewHTMLWriter(ssaDF, s.f, ssaDumpCFG)
// TODO: generate and print a mapping from nodes to values and blocks
dumpSourcesColumn(s.f.HTMLWriter, fn)
s.f.HTMLWriter.WriteAST("AST", astBuf)
// Allocate starting values
s.labels = map[string]*ssaLabel{}
s.labeledNodes = map[*Node]*ssaLabel{}
s.fwdVars = map[*Node]*ssa.Value{}
s.startmem = s.entryNewValue0(ssa.OpInitMem, types.TypeMem)
s.hasOpenDefers = Debug.N == 0 && s.hasdefer && !s.curfn.Func.OpenCodedDeferDisallowed()
switch {
case s.hasOpenDefers && (Ctxt.Flag_shared || Ctxt.Flag_dynlink) && thearch.LinkArch.Name == "386":
// Don't support open-coded defers for 386 ONLY when using shared
// libraries, because there is extra code (added by rewriteToUseGot())
// preceding the deferreturn/ret code that is generated by gencallret()
// that we don't track correctly.
s.hasOpenDefers = false
if s.hasOpenDefers && s.curfn.Func.Exit.Len() > 0 {
// Skip doing open defers if there is any extra exit code (likely
// copying heap-allocated return values or race detection), since
// we will not generate that code in the case of the extra
// deferreturn/ret segment.
s.hasOpenDefers = false
if s.hasOpenDefers &&
s.curfn.Func.numReturns*s.curfn.Func.numDefers > 15 {
// Since we are generating defer calls at every exit for
// open-coded defers, skip doing open-coded defers if there are
// too many returns (especially if there are multiple defers).
// Open-coded defers are most important for improving performance
// for smaller functions (which don't have many returns).
s.hasOpenDefers = false
s.sp = s.entryNewValue0(ssa.OpSP, types.Types[TUINTPTR]) // TODO: use generic pointer type (unsafe.Pointer?) instead = s.entryNewValue0(ssa.OpSB, types.Types[TUINTPTR])
s.vars[&memVar] = s.startmem
if s.hasOpenDefers {
// Create the deferBits variable and stack slot. deferBits is a
// bitmask showing which of the open-coded defers in this function
// have been activated.
deferBitsTemp := tempAt(src.NoXPos, s.curfn, types.Types[TUINT8])
s.deferBitsTemp = deferBitsTemp
// For this value, AuxInt is initialized to zero by default
startDeferBits := s.entryNewValue0(ssa.OpConst8, types.Types[TUINT8])
s.vars[&deferBitsVar] = startDeferBits
s.deferBitsAddr = s.addr(deferBitsTemp)[TUINT8], s.deferBitsAddr, startDeferBits)
// Make sure that the deferBits stack slot is kept alive (for use
// by panics) and stores to deferBits are not eliminated, even if
// all checking code on deferBits in the function exit can be
// eliminated, because the defer statements were all
// unconditional.
s.vars[&memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, deferBitsTemp, s.mem(), false)
// Generate addresses of local declarations
s.decladdrs = map[*Node]*ssa.Value{}
var args []ssa.Param
var results []ssa.Param
for _, n := range fn.Func.Dcl {
switch n.Class() {
case PPARAM:
s.decladdrs[n] = s.entryNewValue2A(ssa.OpLocalAddr, types.NewPtr(n.Type), n, s.sp, s.startmem)
args = append(args, ssa.Param{Type: n.Type, Offset: int32(n.Xoffset)})
s.decladdrs[n] = s.entryNewValue2A(ssa.OpLocalAddr, types.NewPtr(n.Type), n, s.sp, s.startmem)
results = append(results, ssa.Param{Type: n.Type, Offset: int32(n.Xoffset)})
if s.canSSA(n) {
// Save ssa-able PPARAMOUT variables so we can
// store them back to the stack at the end of
// the function.
s.returns = append(s.returns, n)
case PAUTO:
// processed at each use, to prevent Addr coming
// before the decl.
// moved to heap - already handled by frontend
case PFUNC:
// local function - already handled by frontend
s.Fatalf("local variable with class %v unimplemented", n.Class())
// Populate SSAable arguments.
for _, n := range fn.Func.Dcl {
if n.Class() == PPARAM && s.canSSA(n) {
v := s.newValue0A(ssa.OpArg, n.Type, n)
s.vars[n] = v
s.addNamedValue(n, v) // This helps with debugging information, not needed for compilation itself.
// Convert the AST-based IR to the SSA-based IR
// fallthrough to exit
if s.curBlock != nil {
for _, b := range s.f.Blocks {
if b.Pos != src.NoXPos {
// Main call to ssa package to compile function
if s.hasOpenDefers {
return s.f
func dumpSourcesColumn(writer *ssa.HTMLWriter, fn *Node) {
// Read sources of target function fn.
fname := Ctxt.PosTable.Pos(fn.Pos).Filename()
targetFn, err := readFuncLines(fname, fn.Pos.Line(), fn.Func.Endlineno.Line())
if err != nil {
writer.Logf("cannot read sources for function %v: %v", fn, err)
// Read sources of inlined functions.
var inlFns []*ssa.FuncLines
for _, fi := range ssaDumpInlined {
var elno src.XPos
if fi.Name.Defn == nil {
// Endlineno is filled from exported data.
elno = fi.Func.Endlineno
} else {
elno = fi.Name.Defn.Func.Endlineno
fname := Ctxt.PosTable.Pos(fi.Pos).Filename()
fnLines, err := readFuncLines(fname, fi.Pos.Line(), elno.Line())
if err != nil {
writer.Logf("cannot read sources for inlined function %v: %v", fi, err)
inlFns = append(inlFns, fnLines)
if targetFn != nil {
inlFns = append([]*ssa.FuncLines{targetFn}, inlFns...)
writer.WriteSources("sources", inlFns)
func readFuncLines(file string, start, end uint) (*ssa.FuncLines, error) {
f, err := os.Open(os.ExpandEnv(file))
if err != nil {
return nil, err
defer f.Close()
var lines []string
ln := uint(1)
scanner := bufio.NewScanner(f)
for scanner.Scan() && ln <= end {
if ln >= start {
lines = append(lines, scanner.Text())
return &ssa.FuncLines{Filename: file, StartLineno: start, Lines: lines}, nil
// updateUnsetPredPos propagates the earliest-value position information for b
// towards all of b's predecessors that need a position, and recurs on that
// predecessor if its position is updated. B should have a non-empty position.
func (s *state) updateUnsetPredPos(b *ssa.Block) {
if b.Pos == src.NoXPos {
s.Fatalf("Block %s should have a position", b)
bestPos := src.NoXPos
for _, e := range b.Preds {
p := e.Block()
if !p.LackingPos() {
if bestPos == src.NoXPos {
bestPos = b.Pos
for _, v := range b.Values {
if v.LackingPos() {
if v.Pos != src.NoXPos {
// Assume values are still in roughly textual order;
// TODO: could also seek minimum position?
bestPos = v.Pos
p.Pos = bestPos
s.updateUnsetPredPos(p) // We do not expect long chains of these, thus recursion is okay.
// Information about each open-coded defer.
type openDeferInfo struct {
// The ODEFER node representing the function call of the defer
n *Node
// If defer call is closure call, the address of the argtmp where the
// closure is stored.
closure *ssa.Value
// The node representing the argtmp where the closure is stored - used for
// function, method, or interface call, to store a closure that panic
// processing can use for this defer.
closureNode *Node
// If defer call is interface call, the address of the argtmp where the
// receiver is stored
rcvr *ssa.Value
// The node representing the argtmp where the receiver is stored
rcvrNode *Node
// The addresses of the argtmps where the evaluated arguments of the defer
// function call are stored.
argVals []*ssa.Value
// The nodes representing the argtmps where the args of the defer are stored
argNodes []*Node
type state struct {
// configuration (arch) information
config *ssa.Config
// function we're building
f *ssa.Func
// Node for function
curfn *Node
// labels and labeled control flow nodes (OFOR, OFORUNTIL, OSWITCH, OSELECT) in f
labels map[string]*ssaLabel
labeledNodes map[*Node]*ssaLabel
// unlabeled break and continue statement tracking
breakTo *ssa.Block // current target for plain break statement
continueTo *ssa.Block // current target for plain continue statement
// current location where we're interpreting the AST
curBlock *ssa.Block
// variable assignments in the current block (map from variable symbol to ssa value)
// *Node is the unique identifier (an ONAME Node) for the variable.
// TODO: keep a single varnum map, then make all of these maps slices instead?
vars map[*Node]*ssa.Value
// fwdVars are variables that are used before they are defined in the current block.
// This map exists just to coalesce multiple references into a single FwdRef op.
// *Node is the unique identifier (an ONAME Node) for the variable.
fwdVars map[*Node]*ssa.Value
// all defined variables at the end of each block. Indexed by block ID.
defvars []map[*Node]*ssa.Value
// addresses of PPARAM and PPARAMOUT variables.
decladdrs map[*Node]*ssa.Value
// starting values. Memory, stack pointer, and globals pointer
startmem *ssa.Value
sp *ssa.Value
sb *ssa.Value
// value representing address of where deferBits autotmp is stored
deferBitsAddr *ssa.Value
deferBitsTemp *Node
// line number stack. The current line number is top of stack
line []src.XPos
// the last line number processed; it may have been popped
lastPos src.XPos
// list of panic calls by function name and line number.
// Used to deduplicate panic calls.
panics map[funcLine]*ssa.Block
// list of PPARAMOUT (return) variables.
returns []*Node
cgoUnsafeArgs bool
hasdefer bool // whether the function contains a defer statement
softFloat bool
hasOpenDefers bool // whether we are doing open-coded defers
// If doing open-coded defers, list of info about the defer calls in
// scanning order. Hence, at exit we should run these defers in reverse
// order of this list
openDefers []*openDeferInfo
// For open-coded defers, this is the beginning and end blocks of the last
// defer exit code that we have generated so far. We use these to share
// code between exits if the shareDeferExits option (disabled by default)
// is on.
lastDeferExit *ssa.Block // Entry block of last defer exit code we generated
lastDeferFinalBlock *ssa.Block // Final block of last defer exit code we generated
lastDeferCount int // Number of defers encountered at that point
prevCall *ssa.Value // the previous call; use this to tie results to the call op.
type funcLine struct {
f *obj.LSym
base *src.PosBase
line uint
type ssaLabel struct {
target *ssa.Block // block identified by this label
breakTarget *ssa.Block // block to break to in control flow node identified by this label
continueTarget *ssa.Block // block to continue to in control flow node identified by this label
// label returns the label associated with sym, creating it if necessary.
func (s *state) label(sym *types.Sym) *ssaLabel {
lab := s.labels[sym.Name]
if lab == nil {
lab = new(ssaLabel)
s.labels[sym.Name] = lab
return lab
func (s *state) Logf(msg string, args ...interface{}) { s.f.Logf(msg, args...) }
func (s *state) Log() bool { return s.f.Log() }
func (s *state) Fatalf(msg string, args ...interface{}) {
s.f.Frontend().Fatalf(s.peekPos(), msg, args...)
func (s *state) Warnl(pos src.XPos, msg string, args ...interface{}) { s.f.Warnl(pos, msg, args...) }
func (s *state) Debug_checknil() bool { return s.f.Frontend().Debug_checknil() }
var (
// dummy node for the memory variable
memVar = Node{Op: ONAME, Sym: &types.Sym{Name: "mem"}}
// dummy nodes for temporary variables
ptrVar = Node{Op: ONAME, Sym: &types.Sym{Name: "ptr"}}
lenVar = Node{Op: ONAME, Sym: &types.Sym{Name: "len"}}
newlenVar = Node{Op: ONAME, Sym: &types.Sym{Name: "newlen"}}
capVar = Node{Op: ONAME, Sym: &types.Sym{Name: "cap"}}
typVar = Node{Op: ONAME, Sym: &types.Sym{Name: "typ"}}
okVar = Node{Op: ONAME, Sym: &types.Sym{Name: "ok"}}
deferBitsVar = Node{Op: ONAME, Sym: &types.Sym{Name: "deferBits"}}
// startBlock sets the current block we're generating code in to b.
func (s *state) startBlock(b *ssa.Block) {
if s.curBlock != nil {
s.Fatalf("starting block %v when block %v has not ended", b, s.curBlock)
s.curBlock = b
s.vars = map[*Node]*ssa.Value{}
for n := range s.fwdVars {
delete(s.fwdVars, n)
// endBlock marks the end of generating code for the current block.
// Returns the (former) current block. Returns nil if there is no current
// block, i.e. if no code flows to the current execution point.
func (s *state) endBlock() *ssa.Block {
b := s.curBlock
if b == nil {
return nil
for len(s.defvars) <= int(b.ID) {
s.defvars = append(s.defvars, nil)
s.defvars[b.ID] = s.vars
s.curBlock = nil
s.vars = nil
if b.LackingPos() {
// Empty plain blocks get the line of their successor (handled after all blocks created),
// except for increment blocks in For statements (handled in ssa conversion of OFOR),
// and for blocks ending in GOTO/BREAK/CONTINUE.
b.Pos = src.NoXPos
} else {
b.Pos = s.lastPos
return b
// pushLine pushes a line number on the line number stack.
func (s *state) pushLine(line src.XPos) {
if !line.IsKnown() {
// the frontend may emit node with line number missing,
// use the parent line number in this case.
line = s.peekPos()
if Debug.K != 0 {
Warn("buildssa: unknown position (line 0)")
} else {
s.lastPos = line
s.line = append(s.line, line)
// popLine pops the top of the line number stack.
func (s *state) popLine() {
s.line = s.line[:len(s.line)-1]
// peekPos peeks the top of the line number stack.
func (s *state) peekPos() src.XPos {
return s.line[len(s.line)-1]
// newValue0 adds a new value with no arguments to the current block.
func (s *state) newValue0(op ssa.Op, t *types.Type) *ssa.Value {
return s.curBlock.NewValue0(s.peekPos(), op, t)
// newValue0A adds a new value with no arguments and an aux value to the current block.
func (s *state) newValue0A(op ssa.Op, t *types.Type, aux interface{}) *ssa.Value {
return s.curBlock.NewValue0A(s.peekPos(), op, t, aux)
// newValue0I adds a new value with no arguments and an auxint value to the current block.
func (s *state) newValue0I(op ssa.Op, t *types.Type, auxint int64) *ssa.Value {
return s.curBlock.NewValue0I(s.peekPos(), op, t, auxint)
// newValue1 adds a new value with one argument to the current block.
func (s *state) newValue1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
return s.curBlock.NewValue1(s.peekPos(), op, t, arg)
// newValue1A adds a new value with one argument and an aux value to the current block.
func (s *state) newValue1A(op ssa.Op, t *types.Type, aux interface{}, arg *ssa.Value) *ssa.Value {
return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
// newValue1Apos adds a new value with one argument and an aux value to the current block.
// isStmt determines whether the created values may be a statement or not
// (i.e., false means never, yes means maybe).
func (s *state) newValue1Apos(op ssa.Op, t *types.Type, aux interface{}, arg *ssa.Value, isStmt bool) *ssa.Value {
if isStmt {
return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
return s.curBlock.NewValue1A(s.peekPos().WithNotStmt(), op, t, aux, arg)
// newValue1I adds a new value with one argument and an auxint value to the current block.
func (s *state) newValue1I(op ssa.Op, t *types.Type, aux int64, arg *ssa.Value) *ssa.Value {
return s.curBlock.NewValue1I(s.peekPos(), op, t, aux, arg)
// newValue2 adds a new value with two arguments to the current block.
func (s *state) newValue2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
return s.curBlock.NewValue2(s.peekPos(), op, t, arg0, arg1)
// newValue2A adds a new value with two arguments and an aux value to the current block.
func (s *state) newValue2A(op ssa.Op, t *types.Type, aux interface{}, arg0, arg1 *ssa.Value) *ssa.Value {
return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
// newValue2Apos adds a new value with two arguments and an aux value to the current block.
// isStmt determines whether the created values may be a statement or not
// (i.e., false means never, yes means maybe).
func (s *state) newValue2Apos(op ssa.Op, t *types.Type, aux interface{}, arg0, arg1 *ssa.Value, isStmt bool) *ssa.Value {
if isStmt {
return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
return s.curBlock.NewValue2A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1)
// newValue2I adds a new value with two arguments and an auxint value to the current block.
func (s *state) newValue2I(op ssa.Op, t *types.Type, aux int64, arg0, arg1 *ssa.Value) *ssa.Value {
return s.curBlock.NewValue2I(s.peekPos(), op, t, aux, arg0, arg1)
// newValue3 adds a new value with three arguments to the current block.
func (s *state) newValue3(op ssa.Op, t *types.Type, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
return s.curBlock.NewValue3(s.peekPos(), op, t, arg0, arg1, arg2)
// newValue3I adds a new value with three arguments and an auxint value to the current block.
func (s *state) newValue3I(op ssa.Op, t *types.Type, aux int64, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
return s.curBlock.NewValue3I(s.peekPos(), op, t, aux, arg0, arg1, arg2)
// newValue3A adds a new value with three arguments and an aux value to the current block.
func (s *state) newValue3A(op ssa.Op, t *types.Type, aux interface{}, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
// newValue3Apos adds a new value with three arguments and an aux value to the current block.
// isStmt determines whether the created values may be a statement or not
// (i.e., false means never, yes means maybe).
func (s *state) newValue3Apos(op ssa.Op, t *types.Type, aux interface{}, arg0, arg1, arg2 *ssa.Value, isStmt bool) *ssa.Value {
if isStmt {
return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
return s.curBlock.NewValue3A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1, arg2)
// newValue4 adds a new value with four arguments to the current block.
func (s *state) newValue4(op ssa.Op, t *types.Type, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
return s.curBlock.NewValue4(s.peekPos(), op, t, arg0, arg1, arg2, arg3)
// newValue4 adds a new value with four arguments and an auxint value to the current block.
func (s *state) newValue4I(op ssa.Op, t *types.Type, aux int64, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
return s.curBlock.NewValue4I(s.peekPos(), op, t, aux, arg0, arg1, arg2, arg3)
// entryNewValue0 adds a new value with no arguments to the entry block.
func (s *state) entryNewValue0(op ssa.Op, t *types.Type) *ssa.Value {
return s.f.Entry.NewValue0(src.NoXPos, op, t)
// entryNewValue0A adds a new value with no arguments and an aux value to the entry block.
func (s *state) entryNewValue0A(op ssa.Op, t *types.Type, aux interface{}) *ssa.Value {
return s.f.Entry.NewValue0A(src.NoXPos, op, t, aux)
// entryNewValue1 adds a new value with one argument to the entry block.
func (s *state) entryNewValue1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
return s.f.Entry.NewValue1(src.NoXPos, op, t, arg)
// entryNewValue1 adds a new value with one argument and an auxint value to the entry block.
func (s *state) entryNewValue1I(op ssa.Op, t *types.Type, auxint int64, arg *ssa.Value) *ssa.Value {
return s.f.Entry.NewValue1I(src.NoXPos, op, t, auxint, arg)
// entryNewValue1A adds a new value with one argument and an aux value to the entry block.
func (s *state) entryNewValue1A(op ssa.Op, t *types.Type, aux interface{}, arg *ssa.Value) *ssa.Value {
return s.f.Entry.NewValue1A(src.NoXPos, op, t, aux, arg)
// entryNewValue2 adds a new value with two arguments to the entry block.
func (s *state) entryNewValue2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
return s.f.Entry.NewValue2(src.NoXPos, op, t, arg0, arg1)
// entryNewValue2A adds a new value with two arguments and an aux value to the entry block.
func (s *state) entryNewValue2A(op ssa.Op, t *types.Type, aux interface{}, arg0, arg1 *ssa.Value) *ssa.Value {
return s.f.Entry.NewValue2A(src.NoXPos, op, t, aux, arg0, arg1)
// const* routines add a new const value to the entry block.
func (s *state) constSlice(t *types.Type) *ssa.Value {
return s.f.ConstSlice(t)
func (s *state) constInterface(t *types.Type) *ssa.Value {
return s.f.ConstInterface(t)
func (s *state) constNil(t *types.Type) *ssa.Value { return s.f.ConstNil(t) }
func (s *state) constEmptyString(t *types.Type) *ssa.Value {
return s.f.ConstEmptyString(t)
func (s *state) constBool(c bool) *ssa.Value {
return s.f.ConstBool(types.Types[TBOOL], c)
func (s *state) constInt8(t *types.Type, c int8) *ssa.Value {
return s.f.ConstInt8(t, c)
func (s *state) constInt16(t *types.Type, c int16) *ssa.Value {
return s.f.ConstInt16(t, c)
func (s *state) constInt32(t *types.Type, c int32) *ssa.Value {
return s.f.ConstInt32(t, c)
func (s *state) constInt64(t *types.Type, c int64) *ssa.Value {
return s.f.ConstInt64(t, c)
func (s *state) constFloat32(t *types.Type, c float64) *ssa.Value {
return s.f.ConstFloat32(t, c)
func (s *state) constFloat64(t *types.Type, c float64) *ssa.Value {
return s.f.ConstFloat64(t, c)
func (s *state) constInt(t *types.Type, c int64) *ssa.Value {
if s.config.PtrSize == 8 {
return s.constInt64(t, c)
if int64(int32(c)) != c {
s.Fatalf("integer constant too big %d", c)
return s.constInt32(t, int32(c))
func (s *state) constOffPtrSP(t *types.Type, c int64) *ssa.Value {
return s.f.ConstOffPtrSP(t, c, s.sp)
// newValueOrSfCall* are wrappers around newValue*, which may create a call to a
// soft-float runtime function instead (when emitting soft-float code).
func (s *state) newValueOrSfCall1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
if s.softFloat {
if c, ok := s.sfcall(op, arg); ok {
return c
return s.newValue1(op, t, arg)
func (s *state) newValueOrSfCall2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
if s.softFloat {
if c, ok := s.sfcall(op, arg0, arg1); ok {
return c
return s.newValue2(op, t, arg0, arg1)
type instrumentKind uint8
const (
instrumentRead = iota
func (s *state) instrument(t *types.Type, addr *ssa.Value, kind instrumentKind) {
s.instrument2(t, addr, nil, kind)
// instrumentFields instruments a read/write operation on addr.
// If it is instrumenting for MSAN and t is a struct type, it instruments
// operation for each field, instead of for the whole struct.
func (s *state) instrumentFields(t *types.Type, addr *ssa.Value, kind instrumentKind) {
if !flag_msan || !t.IsStruct() {
s.instrument(t, addr, kind)
for _, f := range t.Fields().Slice() {
if f.Sym.IsBlank() {
offptr := s.newValue1I(ssa.OpOffPtr, types.NewPtr(f.Type), f.Offset, addr)
s.instrumentFields(f.Type, offptr, kind)
func (s *state) instrumentMove(t *types.Type, dst, src *ssa.Value) {
if flag_msan {
s.instrument2(t, dst, src, instrumentMove)
} else {
s.instrument(t, src, instrumentRead)
s.instrument(t, dst, instrumentWrite)
func (s *state) instrument2(t *types.Type, addr, addr2 *ssa.Value, kind instrumentKind) {
if !s.curfn.Func.InstrumentBody() {
w := t.Size()
if w == 0 {
return // can't race on zero-sized things
if ssa.IsSanitizerSafeAddr(addr) {
var fn *obj.LSym
needWidth := false
if addr2 != nil && kind != instrumentMove {
panic("instrument2: non-nil addr2 for non-move instrumentation")
if flag_msan {
switch kind {
case instrumentRead:
fn = msanread
case instrumentWrite:
fn = msanwrite
case instrumentMove:
fn = msanmove
needWidth = true
} else if flag_race && t.NumComponents(types.CountBlankFields) > 1 {
// for composite objects we have to write every address
// because a write might happen to any subobject.
// composites with only one element don't have subobjects, though.
switch kind {
case instrumentRead:
fn = racereadrange
case instrumentWrite:
fn = racewriterange
needWidth = true
} else if flag_race {
// for non-composite objects we can write just the start
// address, as any write must write the first byte.
switch kind {
case instrumentRead:
fn = raceread
case instrumentWrite:
fn = racewrite
} else {
args := []*ssa.Value{addr}
if addr2 != nil {
args = append(args, addr2)
if needWidth {
args = append(args, s.constInt(types.Types[TUINTPTR], w))
s.rtcall(fn, true, nil, args...)
func (s *state) load(t *types.Type, src *ssa.Value) *ssa.Value {
s.instrumentFields(t, src, instrumentRead)
return s.rawLoad(t, src)
func (s *state) rawLoad(t *types.Type, src *ssa.Value) *ssa.Value {
return s.newValue2(ssa.OpLoad, t, src, s.mem())
func (s *state) store(t *types.Type, dst, val *ssa.Value) {
s.vars[&memVar] = s.newValue3A(ssa.OpStore, types.TypeMem, t, dst, val, s.mem())
func (s *state) zero(t *types.Type, dst *ssa.Value) {
s.instrument(t, dst, instrumentWrite)
store := s.newValue2I(ssa.OpZero, types.TypeMem, t.Size(), dst, s.mem())
store.Aux = t
s.vars[&memVar] = store
func (s *state) move(t *types.Type, dst, src *ssa.Value) {
s.instrumentMove(t, dst, src)
store := s.newValue3I(ssa.OpMove, types.TypeMem, t.Size(), dst, src, s.mem())
store.Aux = t
s.vars[&memVar] = store
// stmtList converts the statement list n to SSA and adds it to s.
func (s *state) stmtList(l Nodes) {
for _, n := range l.Slice() {
// stmt converts the statement n to SSA and adds it to s.
func (s *state) stmt(n *Node) {
if !(n.Op == OVARKILL || n.Op == OVARLIVE || n.Op == OVARDEF) {
// OVARKILL, OVARLIVE, and OVARDEF are invisible to the programmer, so we don't use their line numbers to avoid confusion in debugging.
defer s.popLine()
// If s.curBlock is nil, and n isn't a label (which might have an associated goto somewhere),
// then this code is dead. Stop here.
if s.curBlock == nil && n.Op != OLABEL {
switch n.Op {
case OBLOCK:
// No-ops
// Expression statements
if isIntrinsicCall(n) {
s.callResult(n, callNormal)
if n.Op == OCALLFUNC && n.Left.Op == ONAME && n.Left.Class() == PFUNC {
if fn := n.Left.Sym.Name; compiling_runtime && fn == "throw" ||
n.Left.Sym.Pkg == Runtimepkg && (fn == "throwinit" || fn == "gopanic" || fn == "panicwrap" || fn == "block" || fn == "panicmakeslicelen" || fn == "panicmakeslicecap") {
m := s.mem()
b := s.endBlock()
b.Kind = ssa.BlockExit
// TODO: never rewrite OPANIC to OCALLFUNC in the
// first place. Need to wait until all backends
// go through SSA.
case ODEFER:
if Debug_defer > 0 {
var defertype string
if s.hasOpenDefers {
defertype = "open-coded"
} else if n.Esc == EscNever {
defertype = "stack-allocated"
} else {
defertype = "heap-allocated"
Warnl(n.Pos, "%s defer", defertype)
if s.hasOpenDefers {
} else {
d := callDefer
if n.Esc == EscNever {
d = callDeferStack
s.callResult(n.Left, d)
case OGO:
s.callResult(n.Left, callGo)
res, resok := s.dottype(n.Right, true)
deref := false
if !canSSAType(n.Right.Type) {
if res.Op != ssa.OpLoad {
s.Fatalf("dottype of non-load")
mem := s.mem()
if mem.Op == ssa.OpVarKill {
mem = mem.Args[0]
if res.Args[1] != mem {
s.Fatalf("memory no longer live from 2-result dottype load")
deref = true
res = res.Args[0]
s.assign(n.List.First(), res, deref, 0)
s.assign(n.List.Second(), resok, false, 0)
case OAS2FUNC:
// We come here only when it is an intrinsic call returning two values.
if !isIntrinsicCall(n.Right) {
s.Fatalf("non-intrinsic AS2FUNC not expanded %v", n.Right)
v := s.intrinsicCall(n.Right)
v1 := s.newValue1(ssa.OpSelect0, n.List.First().Type, v)
v2 := s.newValue1(ssa.OpSelect1, n.List.Second().Type, v)
s.assign(n.List.First(), v1, false, 0)
s.assign(n.List.Second(), v2, false, 0)
case ODCL:
if n.Left.Class() == PAUTOHEAP {
s.Fatalf("DCL %v", n)
case OLABEL:
sym := n.Sym
lab := s.label(sym)
// Associate label with its control flow node, if any
if ctl := n.labeledControl(); ctl != nil {
s.labeledNodes[ctl] = lab
// The label might already have a target block via a goto.
if == nil { = s.f.NewBlock(ssa.BlockPlain)
// Go to that label.
// (We pretend "label:" is preceded by "goto label", unless the predecessor is unreachable.)
if s.curBlock != nil {
b := s.endBlock()
case OGOTO:
sym := n.Sym
lab := s.label(sym)
if == nil { = s.f.NewBlock(ssa.BlockPlain)
b := s.endBlock()
b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
case OAS:
if n.Left == n.Right && n.Left.Op == ONAME {
// An x=x assignment. No point in doing anything
// here. In addition, skipping this assignment
// prevents generating:
// COPY x -> x
// which is bad because x is incorrectly considered
// dead before the vardef. See issue #14904.
// Evaluate RHS.
rhs := n.Right
if rhs != nil {
switch rhs.Op {
// All literals with nonzero fields have already been
// rewritten during walk. Any that remain are just T{}
// or equivalents. Use the zero value.
if !isZero(rhs) {
s.Fatalf("literal with nonzero value in SSA: %v", rhs)
rhs = nil
// Check whether we're writing the result of an append back to the same slice.
// If so, we handle it specially to avoid write barriers on the fast
// (non-growth) path.
if !samesafeexpr(n.Left, rhs.List.First()) || Debug.N != 0 {
// If the slice can be SSA'd, it'll be on the stack,
// so there will be no write barriers,
// so there's no need to attempt to prevent them.
if s.canSSA(n.Left) {
if Debug_append > 0 { // replicating old diagnostic message
Warnl(n.Pos, "append: len-only update (in local slice)")
if Debug_append > 0 {
Warnl(n.Pos, "append: len-only update")
s.append(rhs, true)
if n.Left.isBlank() {
// _ = rhs
// Just evaluate rhs for side-effects.
if rhs != nil {
var t *types.Type
if n.Right != nil {
t = n.Right.Type
} else {
t = n.Left.Type
var r *ssa.Value
deref := !canSSAType(t)
if deref {
if rhs == nil {
r = nil // Signal assign to use OpZero.
} else {
r = s.addr(rhs)
} else {
if rhs == nil {
r = s.zeroVal(t)
} else {
r = s.expr(rhs)
var skip skipMask
if rhs != nil && (rhs.Op == OSLICE || rhs.Op == OSLICE3 || rhs.Op == OSLICESTR) && samesafeexpr(rhs.Left, n.Left) {
// We're assigning a slicing operation back to its source.
// Don't write back fields we aren't changing. See issue #14855.
i, j, k := rhs.SliceBounds()
if i != nil && (i.Op == OLITERAL && i.Val().Ctype() == CTINT && i.Int64Val() == 0) {
// [0:...] is the same as [:...]
i = nil
// TODO: detect defaults for len/cap also.
// Currently doesn't really work because (*p)[:len(*p)] appears here as:
// tmp = len(*p)
// (*p)[:tmp]
//if j != nil && (j.Op == OLEN && samesafeexpr(j.Left, n.Left)) {
// j = nil
//if k != nil && (k.Op == OCAP && samesafeexpr(k.Left, n.Left)) {
// k = nil
if i == nil {
skip |= skipPtr
if j == nil {
skip |= skipLen
if k == nil {
skip |= skipCap
s.assign(n.Left, r, deref, skip)
case OIF:
if Isconst(n.Left, CTBOOL) {
if n.Left.BoolVal() {
} else {
bEnd := s.f.NewBlock(ssa.BlockPlain)
var likely int8
if n.Likely() {
likely = 1
var bThen *ssa.Block
if n.Nbody.Len() != 0 {
bThen = s.f.NewBlock(ssa.BlockPlain)
} else {
bThen = bEnd
var bElse *ssa.Block
if n.Rlist.Len() != 0 {
bElse = s.f.NewBlock(ssa.BlockPlain)
} else {
bElse = bEnd
s.condBranch(n.Left, bThen, bElse, likely)
if n.Nbody.Len() != 0 {
if b := s.endBlock(); b != nil {
if n.Rlist.Len() != 0 {
if b := s.endBlock(); b != nil {
b := s.exit()
b.Pos = s.lastPos.WithIsStmt()
b := s.exit()
b.Kind = ssa.BlockRetJmp // override BlockRet
b.Aux = n.Sym.Linksym()
var to *ssa.Block
if n.Sym == nil {
// plain break/continue
switch n.Op {
to = s.continueTo
case OBREAK:
to = s.breakTo
} else {
// labeled break/continue; look up the target
sym := n.Sym
lab := s.label(sym)
switch n.Op {
to = lab.continueTarget
case OBREAK:
to = lab.breakTarget
b := s.endBlock()
b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
// OFOR: for Ninit; Left; Right { Nbody }
// cond (Left); body (Nbody); incr (Right)
// OFORUNTIL: for Ninit; Left; Right; List { Nbody }
// => body: { Nbody }; incr: Right; if Left { lateincr: List; goto body }; end:
bCond := s.f.NewBlock(ssa.BlockPlain)
bBody := s.f.NewBlock(ssa.BlockPlain)
bIncr := s.f.NewBlock(ssa.BlockPlain)
bEnd := s.f.NewBlock(ssa.BlockPlain)
// ensure empty for loops have correct position; issue #30167
bBody.Pos = n.Pos
// first, jump to condition test (OFOR) or body (OFORUNTIL)
b := s.endBlock()
if n.Op == OFOR {
// generate code to test condition
if n.Left != nil {
s.condBranch(n.Left, bBody, bEnd, 1)
} else {
b := s.endBlock()
b.Kind = ssa.BlockPlain
} else {
// set up for continue/break in body
prevContinue := s.continueTo
prevBreak := s.breakTo
s.continueTo = bIncr
s.breakTo = bEnd
lab := s.labeledNodes[n]
if lab != nil {
// labeled for loop
lab.continueTarget = bIncr
lab.breakTarget = bEnd
// generate body
// tear down continue/break
s.continueTo = prevContinue
s.breakTo = prevBreak
if lab != nil {
lab.continueTarget = nil
lab.breakTarget = nil
// done with body, goto incr
if b := s.endBlock(); b != nil {
// generate incr (and, for OFORUNTIL, condition)
if n.Right != nil {
if n.Op == OFOR {
if b := s.endBlock(); b != nil {
// It can happen that bIncr ends in a block containing only VARKILL,
// and that muddles the debugging experience.
if n.Op != OFORUNTIL && b.Pos == src.NoXPos {
b.Pos = bCond.Pos
} else {
// bCond is unused in OFORUNTIL, so repurpose it.
bLateIncr := bCond
// test condition
s.condBranch(n.Left, bLateIncr, bEnd, 1)
// generate late increment
// These have been mostly rewritten by the front end into their Nbody fields.
// Our main task is to correctly hook up any break statements.
bEnd := s.f.NewBlock(ssa.BlockPlain)
prevBreak := s.breakTo
s.breakTo = bEnd
lab := s.labeledNodes[n]
if lab != nil {
// labeled
lab.breakTarget = bEnd
// generate body code
s.breakTo = prevBreak
if lab != nil {
lab.breakTarget = nil
// walk adds explicit OBREAK nodes to the end of all reachable code paths.
// If we still have a current block here, then mark it unreachable.
if s.curBlock != nil {
m := s.mem()
b := s.endBlock()
b.Kind = ssa.BlockExit
if !s.canSSA(n.Left) {
s.vars[&memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, n.Left, s.mem(), false)
// Insert a varkill op to record that a variable is no longer live.
// We only care about liveness info at call sites, so putting the
// varkill in the store chain is enough to keep it correctly ordered
// with respect to call ops.
if !s.canSSA(n.Left) {
s.vars[&memVar] = s.newValue1Apos(ssa.OpVarKill, types.TypeMem, n.Left, s.mem(), false)
// Insert a varlive op to record that a variable is still live.
if !n.Left.Name.Addrtaken() {
s.Fatalf("VARLIVE variable %v must have Addrtaken set", n.Left)
switch n.Left.Class() {
s.Fatalf("VARLIVE variable %v must be Auto or Arg", n.Left)
s.vars[&memVar] = s.newValue1A(ssa.OpVarLive, types.TypeMem, n.Left, s.mem())
p := s.expr(n.Left)
s.newValue1I(ssa.OpInlMark, types.TypeVoid, n.Xoffset, s.mem())
s.Fatalf("unhandled stmt %v", n.Op)
// If true, share as many open-coded defer exits as possible (with the downside of
// worse line-number information)
const shareDeferExits = false
// exit processes any code that needs to be generated just before returning.
// It returns a BlockRet block that ends the control flow. Its control value
// will be set to the final memory state.
func (s *state) exit() *ssa.Block {
if s.hasdefer {
if s.hasOpenDefers {
if shareDeferExits && s.lastDeferExit != nil && len(s.openDefers) == s.lastDeferCount {
if s.curBlock.Kind != ssa.BlockPlain {
panic("Block for an exit should be BlockPlain")
return s.lastDeferFinalBlock
} else {
s.rtcall(Deferreturn, true, nil)
// Run exit code. Typically, this code copies heap-allocated PPARAMOUT
// variables back to the stack.
// Store SSAable PPARAMOUT variables back to stack locations.
for _, n := range s.returns {
addr := s.decladdrs[n]
val := s.variable(n, n.Type)
s.vars[&memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem()), addr, val)
// TODO: if val is ever spilled, we'd like to use the
// PPARAMOUT slot for spilling it. That won't happen
// currently.
// Do actual return.
m := s.mem()
b := s.endBlock()
b.Kind = ssa.BlockRet
if s.hasdefer && s.hasOpenDefers {
s.lastDeferFinalBlock = b
return b
type opAndType struct {
op Op
etype types.EType
var opToSSA = map[opAndType]ssa.Op{
opAndType{OADD, TINT8}: ssa.OpAdd8,
opAndType{OADD, TUINT8}: ssa.OpAdd8,
opAndType{OADD, TINT16}: ssa.OpAdd16,
opAndType{OADD, TUINT16}: ssa.OpAdd16,
opAndType{OADD, TINT32}: ssa.OpAdd32,
opAndType{OADD, TUINT32}: ssa.OpAdd32,
opAndType{OADD, TINT64}: ssa.OpAdd64,
opAndType{OADD, TUINT64}: ssa.OpAdd64,
opAndType{OADD, TFLOAT32}: ssa.OpAdd32F,
opAndType{OADD, TFLOAT64}: ssa.OpAdd64F,
opAndType{OSUB, TINT8}: ssa.OpSub8,
opAndType{OSUB, TUINT8}: ssa.OpSub8,
opAndType{OSUB, TINT16}: ssa.OpSub16,
opAndType{OSUB, TUINT16}: ssa.OpSub16,
opAndType{OSUB, TINT32}: ssa.OpSub32,
opAndType{OSUB, TUINT32}: ssa.OpSub32,
opAndType{OSUB, TINT64}: ssa.OpSub64,
opAndType{OSUB, TUINT64}: ssa.OpSub64,
opAndType{OSUB, TFLOAT32}: ssa.OpSub32F,
opAndType{OSUB, TFLOAT64}: ssa.OpSub64F,
opAndType{ONOT, TBOOL}: ssa.OpNot,
opAndType{ONEG, TINT8}: ssa.OpNeg8,
opAndType{ONEG, TUINT8}: ssa.OpNeg8,
opAndType{ONEG, TINT16}: ssa.OpNeg16,
opAndType{ONEG, TUINT16}: ssa.OpNeg16,
opAndType{ONEG, TINT32}: ssa.OpNeg32,
opAndType{ONEG, TUINT32}: ssa.OpNeg32,
opAndType{ONEG, TINT64}: ssa.OpNeg64,
opAndType{ONEG, TUINT64}: ssa.OpNeg64,
opAndType{ONEG, TFLOAT32}: ssa.OpNeg32F,
opAndType{ONEG, TFLOAT64}: ssa.OpNeg64F,
opAndType{OBITNOT, TINT8}: ssa.OpCom8,
opAndType{OBITNOT, TUINT8}: ssa.OpCom8,
opAndType{OBITNOT, TINT16}: ssa.OpCom16,
opAndType{OBITNOT, TUINT16}: ssa.OpCom16,
opAndType{OBITNOT, TINT32}: ssa.OpCom32,
opAndType{OBITNOT, TUINT32}: ssa.OpCom32,
opAndType{OBITNOT, TINT64}: ssa.OpCom64,
opAndType{OBITNOT, TUINT64}: ssa.OpCom64,
opAndType{OIMAG, TCOMPLEX64}: ssa.OpComplexImag,
opAndType{OIMAG, TCOMPLEX128}: ssa.OpComplexImag,
opAndType{OREAL, TCOMPLEX64}: ssa.OpComplexReal,
opAndType{OREAL, TCOMPLEX128}: ssa.OpComplexReal,
opAndType{OMUL, TINT8}: ssa.OpMul8,
opAndType{OMUL, TUINT8}: ssa.OpMul8,
opAndType{OMUL, TINT16}: ssa.OpMul16,
opAndType{OMUL, TUINT16}: ssa.OpMul16,
opAndType{OMUL, TINT32}: ssa.OpMul32,
opAndType{OMUL, TUINT32}: ssa.OpMul32,
opAndType{OMUL, TINT64}: ssa.OpMul64,
opAndType{OMUL, TUINT64}: ssa.OpMul64,
opAndType{OMUL, TFLOAT32}: ssa.OpMul32F,
opAndType{OMUL, TFLOAT64}: ssa.OpMul64F,
opAndType{ODIV, TFLOAT32}: ssa.OpDiv32F,
opAndType{ODIV, TFLOAT64}: ssa.OpDiv64F,
opAndType{ODIV, TINT8}: ssa.OpDiv8,
opAndType{ODIV, TUINT8}: ssa.OpDiv8u,
opAndType{ODIV, TINT16}: ssa.OpDiv16,
opAndType{ODIV, TUINT16}: ssa.OpDiv16u,
opAndType{ODIV, TINT32}: ssa.OpDiv32,
opAndType{ODIV, TUINT32}: ssa.OpDiv32u,
opAndType{ODIV, TINT64}: ssa.OpDiv64,
opAndType{ODIV, TUINT64}: ssa.OpDiv64u,
opAndType{OMOD, TINT8}: ssa.OpMod8,
opAndType{OMOD, TUINT8}: ssa.OpMod8u,
opAndType{OMOD, TINT16}: ssa.OpMod16,
opAndType{OMOD, TUINT16}: ssa.OpMod16u,
opAndType{OMOD, TINT32}: ssa.OpMod32,
opAndType{OMOD, TUINT32}: ssa.OpMod32u,
opAndType{OMOD, TINT64}: ssa.OpMod64,
opAndType{OMOD, TUINT64}: ssa.OpMod64u,
opAndType{OAND, TINT8}: ssa.OpAnd8,
opAndType{OAND, TUINT8}: ssa.OpAnd8,
opAndType{OAND, TINT16}: ssa.OpAnd16,
opAndType{OAND, TUINT16}: ssa.OpAnd16,
opAndType{OAND, TINT32}: ssa.OpAnd32,
opAndType{OAND, TUINT32}: ssa.OpAnd32,
opAndType{OAND, TINT64}: ssa.OpAnd64,
opAndType{OAND, TUINT64}: ssa.OpAnd64,
opAndType{OOR, TINT8}: ssa.OpOr8,
opAndType{OOR, TUINT8}: ssa.OpOr8,
opAndType{OOR, TINT16}: ssa.OpOr16,
opAndType{OOR, TUINT16}: ssa.OpOr16,
opAndType{OOR, TINT32}: ssa.OpOr32,
opAndType{OOR, TUINT32}: ssa.OpOr32,
opAndType{OOR, TINT64}: ssa.OpOr64,
opAndType{OOR, TUINT64}: ssa.OpOr64,
opAndType{OXOR, TINT8}: ssa.OpXor8,
opAndType{OXOR, TUINT8}: ssa.OpXor8,
opAndType{OXOR, TINT16}: ssa.OpXor16,
opAndType{OXOR, TUINT16}: ssa.OpXor16,
opAndType{OXOR, TINT32}: ssa.OpXor32,
opAndType{OXOR, TUINT32}: ssa.OpXor32,
opAndType{OXOR, TINT64}: ssa.OpXor64,
opAndType{OXOR, TUINT64}: ssa.OpXor64,
opAndType{OEQ, TBOOL}: ssa.OpEqB,
opAndType{OEQ, TINT8}: ssa.OpEq8,
opAndType{OEQ, TUINT8}: ssa.OpEq8,
opAndType{OEQ, TINT16}: ssa.OpEq16,
opAndType{OEQ, TUINT16}: ssa.OpEq16,
opAndType{OEQ, TINT32}: ssa.OpEq32,
opAndType{OEQ, TUINT32}: ssa.OpEq32,
opAndType{OEQ, TINT64}: ssa.OpEq64,
opAndType{OEQ, TUINT64}: ssa.OpEq64,
opAndType{OEQ, TINTER}: ssa.OpEqInter,
opAndType{OEQ, TSLICE}: ssa.OpEqSlice,
opAndType{OEQ, TFUNC}: ssa.OpEqPtr,
opAndType{OEQ, TMAP}: ssa.OpEqPtr,
opAndType{OEQ, TCHAN}: ssa.OpEqPtr,
opAndType{OEQ, TPTR}: ssa.OpEqPtr,
opAndType{OEQ, TUINTPTR}: ssa.OpEqPtr,
opAndType{OEQ, TUNSAFEPTR}: ssa.OpEqPtr,
opAndType{OEQ, TFLOAT64}: ssa.OpEq64F,
opAndType{OEQ, TFLOAT32}: ssa.OpEq32F,
opAndType{ONE, TBOOL}: ssa.OpNeqB,
opAndType{ONE, TINT8}: ssa.OpNeq8,
opAndType{ONE, TUINT8}: ssa.OpNeq8,
opAndType{ONE, TINT16}: ssa.OpNeq16,
opAndType{ONE, TUINT16}: ssa.OpNeq16,
opAndType{ONE, TINT32}: ssa.OpNeq32,
opAndType{ONE, TUINT32}: ssa.OpNeq32,
opAndType{ONE, TINT64}: ssa.OpNeq64,
opAndType{ONE, TUINT64}: ssa.OpNeq64,
opAndType{ONE, TINTER}: ssa.OpNeqInter,
opAndType{ONE, TSLICE}: ssa.OpNeqSlice,
opAndType{ONE, TFUNC}: ssa.OpNeqPtr,
opAndType{ONE, TMAP}: ssa.OpNeqPtr,
opAndType{ONE, TCHAN}: ssa.OpNeqPtr,
opAndType{ONE, TPTR}: ssa.OpNeqPtr,
opAndType{ONE, TUINTPTR}: ssa.OpNeqPtr,
opAndType{ONE, TUNSAFEPTR}: ssa.OpNeqPtr,
opAndType{ONE, TFLOAT64}: ssa.OpNeq64F,
opAndType{ONE, TFLOAT32}: ssa.OpNeq32F,
opAndType{OLT, TINT8}: ssa.OpLess8,
opAndType{OLT, TUINT8}: ssa.OpLess8U,
opAndType{OLT, TINT16}: ssa.OpLess16,
opAndType{OLT, TUINT16}: ssa.OpLess16U,
opAndType{OLT, TINT32}: ssa.OpLess32,
opAndType{OLT, TUINT32}: ssa.OpLess32U,
opAndType{OLT, TINT64}: ssa.OpLess64,
opAndType{OLT, TUINT64}: ssa.OpLess64U,
opAndType{OLT, TFLOAT64}: ssa.OpLess64F,
opAndType{OLT, TFLOAT32}: ssa.OpLess32F,
opAndType{OLE, TINT8}: ssa.OpLeq8,
opAndType{OLE, TUINT8}: ssa.OpLeq8U,
opAndType{OLE, TINT16}: ssa.OpLeq16,
opAndType{OLE, TUINT16}: ssa.OpLeq16U,
opAndType{OLE, TINT32}: ssa.OpLeq32,
opAndType{OLE, TUINT32}: ssa.OpLeq32U,
opAndType{OLE, TINT64}: ssa.OpLeq64,
opAndType{OLE, TUINT64}: ssa.OpLeq64U,
opAndType{OLE, TFLOAT64}: ssa.OpLeq64F,
opAndType{OLE, TFLOAT32}: ssa.OpLeq32F,
func (s *state) concreteEtype(t *types.Type) types.EType {
e := t.Etype
switch e {
return e
case TINT:
if s.config.PtrSize == 8 {
return TINT64
return TINT32
case TUINT:
if s.config.PtrSize == 8 {
return TUINT64
return TUINT32
if s.config.PtrSize == 8 {
return TUINT64
return TUINT32
func (s *state) ssaOp(op Op, t *types.Type) ssa.Op {
etype := s.concreteEtype(t)
x, ok := opToSSA[opAndType{op, etype}]
if !ok {
s.Fatalf("unhandled binary op %v %s", op, etype)
return x
func floatForComplex(t *types.Type) *types.Type {
switch t.Etype {
case TCOMPLEX64:
return types.Types[TFLOAT32]
case TCOMPLEX128:
return types.Types[TFLOAT64]
Fatalf("unexpected type: %v", t)
return nil
func complexForFloat(t *types.Type) *types.Type {
switch t.Etype {
case TFLOAT32:
return types.Types[TCOMPLEX64]
case TFLOAT64:
return types.Types[TCOMPLEX128]
Fatalf("unexpected type: %v", t)
return nil
type opAndTwoTypes struct {
op Op
etype1 types.EType
etype2 types.EType
type twoTypes struct {
etype1 types.EType
etype2 types.EType
type twoOpsAndType struct {
op1 ssa.Op
op2 ssa.Op
intermediateType types.EType
var fpConvOpToSSA = map[twoTypes]twoOpsAndType{
twoTypes{TINT8, TFLOAT32}: twoOpsAndType{ssa.OpSignExt8to32, ssa.OpCvt32to32F, TINT32},
twoTypes{TINT16, TFLOAT32}: twoOpsAndType{ssa.OpSignExt16to32, ssa.OpCvt32to32F, TINT32},
twoTypes{TINT32, TFLOAT32}: twoOpsAndType{ssa.OpCopy, ssa.OpCvt32to32F, TINT32},
twoTypes{TINT64, TFLOAT32}: twoOpsAndType{ssa.OpCopy, ssa.OpCvt64to32F, TINT64},
twoTypes{TINT8, TFLOAT64}: twoOpsAndType{ssa.OpSignExt8to32, ssa.OpCvt32to64F, TINT32},
twoTypes{TINT16, TFLOAT64}: twoOpsAndType{ssa.OpSignExt16to32, ssa.OpCvt32to64F, TINT32},
twoTypes{TINT32, TFLOAT64}: twoOpsAndType{ssa.OpCopy, ssa.OpCvt32to64F, TINT32},
twoTypes{TINT64, TFLOAT64}: twoOpsAndType{ssa.OpCopy, ssa.OpCvt64to64F, TINT64},
twoTypes{TFLOAT32, TINT8}: twoOpsAndType{ssa.OpCvt32Fto32, ssa.OpTrunc32to8, TINT32},
twoTypes{TFLOAT32, TINT16}: twoOpsAndType{ssa.OpCvt32Fto32, ssa.OpTrunc32to16, TINT32},
twoTypes{TFLOAT32, TINT32}: twoOpsAndType{ssa.OpCvt32Fto32, ssa.OpCopy, TINT32},
twoTypes{TFLOAT32, TINT64}: twoOpsAndType{ssa.OpCvt32Fto64, ssa.OpCopy, TINT64},
twoTypes{TFLOAT64, TINT8}: twoOpsAndType{ssa.OpCvt64Fto32, ssa.OpTrunc32to8, TINT32},
twoTypes{TFLOAT64, TINT16}: twoOpsAndType{ssa.OpCvt64Fto32, ssa.OpTrunc32to16, TINT32},
twoTypes{TFLOAT64, TINT32}: twoOpsAndType{ssa.OpCvt64Fto32, ssa.OpCopy, TINT32},
twoTypes{TFLOAT64, TINT64}: twoOpsAndType{ssa.OpCvt64Fto64, ssa.OpCopy, TINT64},
// unsigned
twoTypes{TUINT8, TFLOAT32}: twoOpsAndType{ssa.OpZeroExt8to32, ssa.OpCvt32to32F, TINT32},
twoTypes{TUINT16, TFLOAT32}: twoOpsAndType{ssa.OpZeroExt16to32, ssa.OpCvt32to32F, TINT32},
twoTypes{TUINT32, TFLOAT32}: twoOpsAndType{ssa.OpZeroExt32to64, ssa.OpCvt64to32F, TINT64}, // go wide to dodge unsigned
twoTypes{TUINT64, TFLOAT32}: twoOpsAndType{ssa.OpCopy, ssa.OpInvalid, TUINT64}, // Cvt64Uto32F, branchy code expansion instead
twoTypes{TUINT8, TFLOAT64}: twoOpsAndType{ssa.OpZeroExt8to32, ssa.OpCvt32to64F, TINT32},
twoTypes{TUINT16, TFLOAT64}: twoOpsAndType{ssa.OpZeroExt16to32, ssa.OpCvt32to64F, TINT32},
twoTypes{TUINT32, TFLOAT64}: twoOpsAndType{ssa.OpZeroExt32to64, ssa.OpCvt64to64F, TINT64}, // go wide to dodge unsigned
twoTypes{TUINT64, TFLOAT64}: twoOpsAndType{ssa.OpCopy, ssa.OpInvalid, TUINT64}, // Cvt64Uto64F, branchy code expansion instead
twoTypes{TFLOAT32, TUINT8}: twoOpsAndType{ssa.OpCvt32Fto32, ssa.OpTrunc32to8, TINT32},
twoTypes{TFLOAT32, TUINT16}: twoOpsAndType{ssa.OpCvt32Fto32, ssa.OpTrunc32to16, TINT32},
twoTypes{TFLOAT32, TUINT32}: twoOpsAndType{ssa.OpCvt32Fto64, ssa.OpTrunc64to32, TINT64}, // go wide to dodge unsigned
twoTypes{TFLOAT32, TUINT64}: twoOpsAndType{ssa.OpInvalid, ssa.OpCopy, TUINT64}, // Cvt32Fto64U, branchy code expansion instead
twoTypes{TFLOAT64, TUINT8}: twoOpsAndType{ssa.OpCvt64Fto32, ssa.OpTrunc32to8, TINT32},
twoTypes{TFLOAT64, TUINT16}: twoOpsAndType{ssa.OpCvt64Fto32, ssa.OpTrunc32to16, TINT32},
twoTypes{TFLOAT64, TUINT32}: twoOpsAndType{ssa.OpCvt64Fto64, ssa.OpTrunc64to32, TINT64}, // go wide to dodge unsigned
twoTypes{TFLOAT64, TUINT64}: twoOpsAndType{ssa.OpInvalid, ssa.OpCopy, TUINT64}, // Cvt64Fto64U, branchy code expansion instead
// float
twoTypes{TFLOAT64, TFLOAT32}: twoOpsAndType{ssa.OpCvt64Fto32F, ssa.OpCopy, TFLOAT32},
twoTypes{TFLOAT64, TFLOAT64}: twoOpsAndType{ssa.OpRound64F, ssa.OpCopy, TFLOAT64},
twoTypes{TFLOAT32, TFLOAT32}: twoOpsAndType{ssa.OpRound32F, ssa.OpCopy, TFLOAT32},
twoTypes{TFLOAT32, TFLOAT64}: twoOpsAndType{ssa.OpCvt32Fto64F, ssa.OpCopy, TFLOAT64},
// this map is used only for 32-bit arch, and only includes the difference
// on 32-bit arch, don't use int64<->float conversion for uint32
var fpConvOpToSSA32 = map[twoTypes]twoOpsAndType{
twoTypes{TUINT32, TFLOAT32}: twoOpsAndType{ssa.OpCopy, ssa.OpCvt32Uto32F, TUINT32},
twoTypes{TUINT32, TFLOAT64}: twoOpsAndType{ssa.OpCopy, ssa.OpCvt32Uto64F, TUINT32},
twoTypes{TFLOAT32, TUINT32}: twoOpsAndType{ssa.OpCvt32Fto32U, ssa.OpCopy, TUINT32},
twoTypes{TFLOAT64, TUINT32}: twoOpsAndType{ssa.OpCvt64Fto32U, ssa.OpCopy, TUINT32},
// uint64<->float conversions, only on machines that have instructions for that
var uint64fpConvOpToSSA = map[twoTypes]twoOpsAndType{
twoTypes{TUINT64, TFLOAT32}: twoOpsAndType{ssa.OpCopy, ssa.OpCvt64Uto32F, TUINT64},
twoTypes{TUINT64, TFLOAT64}: twoOpsAndType{ssa.OpCopy, ssa.OpCvt64Uto64F, TUINT64},
twoTypes{TFLOAT32, TUINT64}: twoOpsAndType{ssa.OpCvt32Fto64U, ssa.OpCopy, TUINT64},
twoTypes{TFLOAT64, TUINT64}: twoOpsAndType{ssa.OpCvt64Fto64U, ssa.OpCopy, TUINT64},
var shiftOpToSSA = map[opAndTwoTypes]ssa.Op{
opAndTwoTypes{OLSH, TINT8, TUINT8}: ssa.OpLsh8x8,
opAndTwoTypes{OLSH, TUINT8, TUINT8}: ssa.OpLsh8x8,
opAndTwoTypes{OLSH, TINT8, TUINT16}: ssa.OpLsh8x16,
opAndTwoTypes{OLSH, TUINT8, TUINT16}: ssa.OpLsh8x16,
opAndTwoTypes{OLSH, TINT8, TUINT32}: ssa.OpLsh8x32,
opAndTwoTypes{OLSH, TUINT8, TUINT32}: ssa.OpLsh8x32,
opAndTwoTypes{OLSH, TINT8, TUINT64}: ssa.OpLsh8x64,
opAndTwoTypes{OLSH, TUINT8, TUINT64}: ssa.OpLsh8x64,
opAndTwoTypes{OLSH, TINT16, TUINT8}: ssa.OpLsh16x8,
opAndTwoTypes{OLSH, TUINT16, TUINT8}: ssa.OpLsh16x8,
opAndTwoTypes{OLSH, TINT16, TUINT16}: ssa.OpLsh16x16,
opAndTwoTypes{OLSH, TUINT16, TUINT16}: ssa.OpLsh16x16,
opAndTwoTypes{OLSH, TINT16, TUINT32}: ssa.OpLsh16x32,
opAndTwoTypes{OLSH, TUINT16, TUINT32}: ssa.OpLsh16x32,
opAndTwoTypes{OLSH, TINT16, TUINT64}: ssa.OpLsh16x64,
opAndTwoTypes{OLSH, TUINT16, TUINT64}: ssa.OpLsh16x64,
opAndTwoTypes{OLSH, TINT32, TUINT8}: ssa.OpLsh32x8,
opAndTwoTypes{OLSH, TUINT32, TUINT8}: ssa.OpLsh32x8,
opAndTwoTypes{OLSH, TINT32, TUINT16}: ssa.OpLsh32x16,
opAndTwoTypes{OLSH, TUINT32, TUINT16}: ssa.OpLsh32x16,
opAndTwoTypes{OLSH, TINT32, TUINT32}: ssa.OpLsh32x32,
opAndTwoTypes{OLSH, TUINT32, TUINT32}: ssa.OpLsh32x32,
opAndTwoTypes{OLSH, TINT32, TUINT64}: ssa.OpLsh32x64,
opAndTwoTypes{OLSH, TUINT32, TUINT64}: ssa.OpLsh32x64,
opAndTwoTypes{OLSH, TINT64, TUINT8}: ssa.OpLsh64x8,
opAndTwoTypes{OLSH, TUINT64, TUINT8}: ssa.OpLsh64x8,
opAndTwoTypes{OLSH, TINT64, TUINT16}: ssa.OpLsh64x16,
opAndTwoTypes{OLSH, TUINT64, TUINT16}: ssa.OpLsh64x16,
opAndTwoTypes{OLSH, TINT64, TUINT32}: ssa.OpLsh64x32,
opAndTwoTypes{OLSH, TUINT64, TUINT32}: ssa.OpLsh64x32,
opAndTwoTypes{OLSH, TINT64, TUINT64}: ssa.OpLsh64x64,
opAndTwoTypes{OLSH, TUINT64, TUINT64}: ssa.OpLsh64x64,
opAndTwoTypes{ORSH, TINT8, TUINT8}: ssa.OpRsh8x8,
opAndTwoTypes{ORSH, TUINT8, TUINT8}: ssa.OpRsh8Ux8,
opAndTwoTypes{ORSH, TINT8, TUINT16}: ssa.OpRsh8x16,
opAndTwoTypes{ORSH, TUINT8, TUINT16}: ssa.OpRsh8Ux16,
opAndTwoTypes{ORSH, TINT8, TUINT32}: ssa.OpRsh8x32,
opAndTwoTypes{ORSH, TUINT8, TUINT32}: ssa.OpRsh8Ux32,
opAndTwoTypes{ORSH, TINT8, TUINT64}: ssa.OpRsh8x64,
opAndTwoTypes{ORSH, TUINT8, TUINT64}: ssa.OpRsh8Ux64,
opAndTwoTypes{ORSH, TINT16, TUINT8}: ssa.OpRsh16x8,
opAndTwoTypes{ORSH, TUINT16, TUINT8}: ssa.OpRsh16Ux8,
opAndTwoTypes{ORSH, TINT16, TUINT16}: ssa.OpRsh16x16,
opAndTwoTypes{ORSH, TUINT16, TUINT16}: ssa.OpRsh16Ux16,
opAndTwoTypes{ORSH, TINT16, TUINT32}: ssa.OpRsh16x32,
opAndTwoTypes{ORSH, TUINT16, TUINT32}: ssa.OpRsh16Ux32,
opAndTwoTypes{ORSH, TINT16, TUINT64}: ssa.OpRsh16x64,
opAndTwoTypes{ORSH, TUINT16, TUINT64}: ssa.OpRsh16Ux64,
opAndTwoTypes{ORSH, TINT32, TUINT8}: ssa.OpRsh32x8,
opAndTwoTypes{ORSH, TUINT32, TUINT8}: ssa.OpRsh32Ux8,
opAndTwoTypes{ORSH, TINT32, TUINT16}: ssa.OpRsh32x16,
opAndTwoTypes{ORSH, TUINT32, TUINT16}: ssa.OpRsh32Ux16,
opAndTwoTypes{ORSH, TINT32, TUINT32}: ssa.OpRsh32x32,
opAndTwoTypes{ORSH, TUINT32, TUINT32}: ssa.OpRsh32Ux32,
opAndTwoTypes{ORSH, TINT32, TUINT64}: ssa.OpRsh32x64,
opAndTwoTypes{ORSH, TUINT32, TUINT64}: ssa.OpRsh32Ux64,
opAndTwoTypes{ORSH, TINT64, TUINT8}: ssa.OpRsh64x8,
opAndTwoTypes{ORSH, TUINT64, TUINT8}: ssa.OpRsh64Ux8,
opAndTwoTypes{ORSH, TINT64, TUINT16}: ssa.OpRsh64x16,
opAndTwoTypes{ORSH, TUINT64, TUINT16}: ssa.OpRsh64Ux16,
opAndTwoTypes{ORSH, TINT64, TUINT32}: ssa.OpRsh64x32,
opAndTwoTypes{ORSH, TUINT64, TUINT32}: ssa.OpRsh64Ux32,
opAndTwoTypes{ORSH, TINT64, TUINT64}: ssa.OpRsh64x64,
opAndTwoTypes{ORSH, TUINT64, TUINT64}: ssa.OpRsh64Ux64,
func (s *state) ssaShiftOp(op Op, t *types.Type, u *types.Type) ssa.Op {
etype1 := s.concreteEtype(t)
etype2 := s.concreteEtype(u)
x, ok := shiftOpToSSA[opAndTwoTypes{op, etype1, etype2}]
if !ok {
s.Fatalf("unhandled shift op %v etype=%s/%s", op, etype1, etype2)
return x
// expr converts the expression n to ssa, adds it to s and returns the ssa result.
func (s *state) expr(n *Node) *ssa.Value {
if !(n.Op == ONAME || n.Op == OLITERAL && n.Sym != nil) {
// ONAMEs and named OLITERALs have the line number
// of the decl, not the use. See issue 14742.
defer s.popLine()
switch n.Op {
slice := s.expr(n.Left)
ptr := s.newValue1(ssa.OpSlicePtr, s.f.Config.Types.BytePtr, slice)
len := s.newValue1(ssa.OpSliceLen, types.Types[TINT], slice)
return s.newValue2(ssa.OpStringMake, n.Type, ptr, len)
str := s.expr(n.Left)
ptr := s.newValue1(ssa.OpStringPtr, s.f.Config.Types.BytePtr, str)
len := s.newValue1(ssa.OpStringLen, types.Types[TINT], str)
return s.newValue3(ssa.OpSliceMake, n.Type, ptr, len, len)
case OCFUNC:
aux := n.Left.Sym.Linksym()
return s.entryNewValue1A(ssa.OpAddr, n.Type, aux,
case ONAME:
if n.Class() == PFUNC {
// "value" of a function is the address of the function's closure
sym := funcsym(n.Sym).Linksym()
return s.entryNewValue1A(ssa.OpAddr, types.NewPtr(n.Type), sym,
if s.canSSA(n) {
return s.variable(n, n.Type)
addr := s.addr(n)
return s.load(n.Type, addr)
addr := s.addr(n)
return s.load(n.Type, addr)
switch u := n.Val().U.(type) {
case *Mpint:
i := u.Int64()
switch n.Type.Size() {
case 1:
return s.constInt8(n.Type, int8(i))
case 2:
return s.constInt16(n.Type, int16(i))
case 4:
return s.constInt32(n.Type, int32(i))
case 8:
return s.constInt64(n.Type, i)
s.Fatalf("bad integer size %d", n.Type.Size())
return nil
case string:
if u == "" {
return s.constEmptyString(n.Type)
return s.entryNewValue0A(ssa.OpConstString, n.Type, u)
case bool:
return s.constBool(u)
case *NilVal:
t := n.Type
switch {
case t.IsSlice():
return s.constSlice(t)
case t.IsInterface():
return s.constInterface(t)
return s.constNil(t)
case *Mpflt:
switch n.Type.Size() {
case 4:
return s.constFloat32(n.Type, u.Float32())
case 8:
return s.constFloat64(n.Type, u.Float64())
s.Fatalf("bad float size %d", n.Type.Size())
return nil
case *Mpcplx:
r := &u.Real
i := &u.Imag
switch n.Type.Size() {
case 8:
pt := types.Types[TFLOAT32]
return s.newValue2(ssa.OpComplexMake, n.Type,
s.constFloat32(pt, r.Float32()),
s.constFloat32(pt, i.Float32()))
case 16:
pt := types.Types[TFLOAT64]
return s.newValue2(ssa.OpComplexMake, n.Type,
s.constFloat64(pt, r.Float64()),
s.constFloat64(pt, i.Float64()))
s.Fatalf("bad float size %d", n.Type.Size())
return nil
s.Fatalf("unhandled OLITERAL %v", n.Val().Ctype())
return nil
to := n.Type
from := n.Left.Type
// Assume everything will work out, so set up our return value.
// Anything interesting that happens from here is a fatal.
x := s.expr(n.Left)
// Special case for not confusing GC and liveness.
// We don't want pointers accidentally classified
// as not-pointers or vice-versa because of copy
// elision.
if to.IsPtrShaped() != from.IsPtrShaped() {
return s.newValue2(ssa.OpConvert, to, x, s.mem())
v := s.newValue1(ssa.OpCopy, to, x) // ensure that v has the right type
// CONVNOP closure
if to.Etype == TFUNC && from.IsPtrShaped() {
return v
// named <--> unnamed type or typed <--> untyped const
if from.Etype == to.Etype {
return v
// unsafe.Pointer <--> *T
if to.IsUnsafePtr() && from.IsPtrShaped() || from.IsUnsafePtr() && to.IsPtrShaped() {
return v
// map <--> *hmap
if to.Etype == TMAP && from.IsPtr() &&
to.MapType().Hmap == from.Elem() {
return v
if from.Width != to.Width {
s.Fatalf("CONVNOP width mismatch %v (%d) -> %v (%d)\n", from, from.Width, to, to.Width)
return nil
if etypesign(from.Etype) != etypesign(to.Etype) {
s.Fatalf("CONVNOP sign mismatch %v (%s) -> %v (%s)\n", from, from.Etype, to, to.Etype)
return nil
if instrumenting {
// These appear to be fine, but they fail the
// integer constraint below, so okay them here.
// Sample non-integer conversion: map[string]string -> *uint8
return v
if etypesign(from.Etype) == 0 {
s.Fatalf("CONVNOP unrecognized non-integer %v -> %v\n", from, to)
return nil
// integer, same width, same sign
return v
case OCONV:
x := s.expr(n.Left)
ft := n.Left.Type // from type
tt := n.Type // to type
if ft.IsBoolean() && tt.IsKind(TUINT8) {
// Bool -> uint8 is generated internally when indexing into runtime.staticbyte.
return s.newValue1(ssa.OpCopy, n.Type, x)
if ft.IsInteger() && tt.IsInteger() {
var op ssa.Op
if tt.Size() == ft.Size() {
op = ssa.OpCopy
} else if tt.Size() < ft.Size() {
// truncation
switch 10*ft.Size() + tt.Size() {
case 21:
op = ssa.OpTrunc16to8
case 41:
op = ssa.OpTrunc32to8
case 42:
op = ssa.OpTrunc32to16
case 81:
op = ssa.OpTrunc64to8
case 82:
op = ssa.OpTrunc64to16
case 84:
op = ssa.OpTrunc64to32
s.Fatalf("weird integer truncation %v -> %v", ft, tt)
} else if ft.IsSigned() {
// sign extension
switch 10*ft.Size() + tt.Size() {
case 12:
op = ssa.OpSignExt8to16
case 14:
op = ssa.OpSignExt8to32
case 18:
op = ssa.OpSignExt8to64
case 24:
op = ssa.OpSignExt16to32
case 28:
op = ssa.OpSignExt16to64
case 48:
op = ssa.OpSignExt32to64
s.Fatalf("bad integer sign extension %v -> %v", ft, tt)
} else {
// zero extension
switch 10*ft.Size() + tt.Size() {
case 12:
op = ssa.OpZeroExt8to16
case 14:
op = ssa.OpZeroExt8to32
case 18:
op = ssa.OpZeroExt8to64
case 24:
op = ssa.OpZeroExt16to32
case 28:
op = ssa.OpZeroExt16to64
case 48:
op = ssa.OpZeroExt32to64
s.Fatalf("weird integer sign extension %v -> %v", ft, tt)
return s.newValue1(op, n.Type, x)
if ft.IsFloat() || tt.IsFloat() {
conv, ok := fpConvOpToSSA[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]
if s.config.RegSize == 4 && thearch.LinkArch.Family != sys.MIPS && !s.softFloat {
if conv1, ok1 := fpConvOpToSSA32[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
conv = conv1
if thearch.LinkArch.Family == sys.ARM64 || thearch.LinkArch.Family == sys.Wasm || thearch.LinkArch.Family == sys.S390X || s.softFloat {
if conv1, ok1 := uint64fpConvOpToSSA[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
conv = conv1
if thearch.LinkArch.Family == sys.MIPS && !s.softFloat {
if ft.Size() == 4 &&a