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Commit 3134ab3c authored by Keith Randall's avatar Keith Randall
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cmd/compile: redo nil checks 

Get rid of BlockCheck. Josh goaded me into it, and I went
down a rabbithole making it happen.

NilCheck now panics if the pointer is nil and returns void, as before.
BlockCheck is gone, and NilCheck is no longer a Control value for
any block. It just exists (and deadcode knows not to throw it away).

I rewrote the nilcheckelim pass to handle this case.  In particular,
there can now be multiple NilCheck ops per block.

I moved all of the arch-dependent nil check elimination done as
part of ssaGenValue into its own proper pass, so we don't have to
duplicate that code for every architecture.

Making the arch-dependent nil check its own pass means I needed
to add a bunch of flags to the opcode table so I could write
the code without arch-dependent ops everywhere.

Change-Id: I419f891ac9b0de313033ff09115c374163416a9f
Reviewed-on: https://go-review.googlesource.com/29120
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: default avatarDavid Chase <drchase@google.com>
parent f9e9412c
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Inline Side-by-side
Showing with 1347 additions and 1532 deletions
src/cmd/compile/internal/amd64/ssa.go
View file @ 3134ab3c
......@@ -905,64 +905,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
case ssa.OpKeepAlive:
gc.KeepAlive(v)
case ssa.OpAMD64LoweredNilCheck:
// Optimization - if the subsequent block has a load or store
// at the same address, we don't need to issue this instruction.
mem := v.Args[1]
for _, w := range v.Block.Succs[0].Block().Values {
if w.Op == ssa.OpPhi {
if w.Type.IsMemory() {
mem = w
}
continue
}
if len(w.Args) == 0 || !w.Args[len(w.Args)-1].Type.IsMemory() {
// w doesn't use a store - can't be a memory op.
continue
}
if w.Args[len(w.Args)-1] != mem {
v.Fatalf("wrong store after nilcheck v=%s w=%s", v, w)
}
switch w.Op {
case ssa.OpAMD64MOVQload, ssa.OpAMD64MOVLload, ssa.OpAMD64MOVWload, ssa.OpAMD64MOVBload,
ssa.OpAMD64MOVQstore, ssa.OpAMD64MOVLstore, ssa.OpAMD64MOVWstore, ssa.OpAMD64MOVBstore,
ssa.OpAMD64MOVBQSXload, ssa.OpAMD64MOVWQSXload, ssa.OpAMD64MOVLQSXload,
ssa.OpAMD64MOVSSload, ssa.OpAMD64MOVSDload, ssa.OpAMD64MOVOload,
ssa.OpAMD64MOVSSstore, ssa.OpAMD64MOVSDstore, ssa.OpAMD64MOVOstore,
ssa.OpAMD64MOVQatomicload, ssa.OpAMD64MOVLatomicload,
ssa.OpAMD64CMPXCHGQlock, ssa.OpAMD64CMPXCHGLlock,
ssa.OpAMD64ANDBlock, ssa.OpAMD64ORBlock:
if w.Args[0] == v.Args[0] && w.Aux == nil && w.AuxInt >= 0 && w.AuxInt < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpAMD64XCHGL, ssa.OpAMD64XCHGQ, ssa.OpAMD64XADDLlock, ssa.OpAMD64XADDQlock:
if w.Args[1] == v.Args[0] && w.Aux == nil && w.AuxInt >= 0 && w.AuxInt < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpAMD64MOVQstoreconst, ssa.OpAMD64MOVLstoreconst, ssa.OpAMD64MOVWstoreconst, ssa.OpAMD64MOVBstoreconst:
off := ssa.ValAndOff(v.AuxInt).Off()
if w.Args[0] == v.Args[0] && w.Aux == nil && off >= 0 && off < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
}
if w.Type.IsMemory() || w.Type.IsTuple() && w.Type.FieldType(1).IsMemory() {
if w.Op == ssa.OpVarDef || w.Op == ssa.OpVarKill || w.Op == ssa.OpVarLive {
// these ops are OK
mem = w
continue
}
// We can't delay the nil check past the next store.
break
}
}
// Issue a load which will fault if the input is nil.
// TODO: We currently use the 2-byte instruction TESTB AX, (reg).
// Should we use the 3-byte TESTB $0, (reg) instead? It is larger
......@@ -1065,7 +1007,7 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
s.SetLineno(b.Line)
switch b.Kind {
case ssa.BlockPlain, ssa.BlockCheck:
case ssa.BlockPlain:
if b.Succs[0].Block() != next {
p := gc.Prog(obj.AJMP)
p.To.Type = obj.TYPE_BRANCH
......
src/cmd/compile/internal/arm/ssa.go
View file @ 3134ab3c
......@@ -771,63 +771,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
p.To.Sym = gc.Linksym(gc.Pkglookup("duffcopy", gc.Runtimepkg))
p.To.Offset = v.AuxInt
case ssa.OpARMLoweredNilCheck:
// Optimization - if the subsequent block has a load or store
// at the same address, we don't need to issue this instruction.
mem := v.Args[1]
for _, w := range v.Block.Succs[0].Block().Values {
if w.Op == ssa.OpPhi {
if w.Type.IsMemory() {
mem = w
}
continue
}
if len(w.Args) == 0 || !w.Args[len(w.Args)-1].Type.IsMemory() {
// w doesn't use a store - can't be a memory op.
continue
}
if w.Args[len(w.Args)-1] != mem {
v.Fatalf("wrong store after nilcheck v=%s w=%s", v, w)
}
switch w.Op {
case ssa.OpARMMOVBload, ssa.OpARMMOVBUload, ssa.OpARMMOVHload, ssa.OpARMMOVHUload,
ssa.OpARMMOVWload, ssa.OpARMMOVFload, ssa.OpARMMOVDload,
ssa.OpARMMOVBstore, ssa.OpARMMOVHstore, ssa.OpARMMOVWstore,
ssa.OpARMMOVFstore, ssa.OpARMMOVDstore:
// arg0 is ptr, auxint is offset
if w.Args[0] == v.Args[0] && w.Aux == nil && w.AuxInt >= 0 && w.AuxInt < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpARMDUFFZERO, ssa.OpARMLoweredZero:
// arg0 is ptr
if w.Args[0] == v.Args[0] {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpARMDUFFCOPY, ssa.OpARMLoweredMove:
// arg0 is dst ptr, arg1 is src ptr
if w.Args[0] == v.Args[0] || w.Args[1] == v.Args[0] {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
default:
}
if w.Type.IsMemory() {
if w.Op == ssa.OpVarDef || w.Op == ssa.OpVarKill || w.Op == ssa.OpVarLive {
// these ops are OK
mem = w
continue
}
// We can't delay the nil check past the next store.
break
}
}
// Issue a load which will fault if arg is nil.
p := gc.Prog(arm.AMOVB)
p.From.Type = obj.TYPE_MEM
......@@ -994,7 +937,7 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
s.SetLineno(b.Line)
switch b.Kind {
case ssa.BlockPlain, ssa.BlockCheck:
case ssa.BlockPlain:
if b.Succs[0].Block() != next {
p := gc.Prog(obj.AJMP)
p.To.Type = obj.TYPE_BRANCH
......
src/cmd/compile/internal/arm64/ssa.go
View file @ 3134ab3c
......@@ -771,71 +771,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
gc.Maxarg = v.AuxInt
}
case ssa.OpARM64LoweredNilCheck:
// Optimization - if the subsequent block has a load or store
// at the same address, we don't need to issue this instruction.
mem := v.Args[1]
for _, w := range v.Block.Succs[0].Block().Values {
if w.Op == ssa.OpPhi {
if w.Type.IsMemory() {
mem = w
}
continue
}
if len(w.Args) == 0 || !w.Args[len(w.Args)-1].Type.IsMemory() {
// w doesn't use a store - can't be a memory op.
continue
}
if w.Args[len(w.Args)-1] != mem {
v.Fatalf("wrong store after nilcheck v=%s w=%s", v, w)
}
switch w.Op {
case ssa.OpARM64MOVBload, ssa.OpARM64MOVBUload, ssa.OpARM64MOVHload, ssa.OpARM64MOVHUload,
ssa.OpARM64MOVWload, ssa.OpARM64MOVWUload, ssa.OpARM64MOVDload,
ssa.OpARM64FMOVSload, ssa.OpARM64FMOVDload,
ssa.OpARM64LDAR, ssa.OpARM64LDARW,
ssa.OpARM64MOVBstore, ssa.OpARM64MOVHstore, ssa.OpARM64MOVWstore, ssa.OpARM64MOVDstore,
ssa.OpARM64FMOVSstore, ssa.OpARM64FMOVDstore,
ssa.OpARM64MOVBstorezero, ssa.OpARM64MOVHstorezero, ssa.OpARM64MOVWstorezero, ssa.OpARM64MOVDstorezero,
ssa.OpARM64STLR, ssa.OpARM64STLRW,
ssa.OpARM64LoweredAtomicExchange64, ssa.OpARM64LoweredAtomicExchange32,
ssa.OpARM64LoweredAtomicAdd64, ssa.OpARM64LoweredAtomicAdd32,
ssa.OpARM64LoweredAtomicCas64, ssa.OpARM64LoweredAtomicCas32,
ssa.OpARM64LoweredAtomicAnd8, ssa.OpARM64LoweredAtomicOr8:
// arg0 is ptr, auxint is offset (atomic ops have auxint 0)
if w.Args[0] == v.Args[0] && w.Aux == nil && w.AuxInt >= 0 && w.AuxInt < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpARM64DUFFZERO, ssa.OpARM64LoweredZero:
// arg0 is ptr
if w.Args[0] == v.Args[0] {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpARM64LoweredMove:
// arg0 is dst ptr, arg1 is src ptr
if w.Args[0] == v.Args[0] || w.Args[1] == v.Args[0] {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
default:
}
if w.Type.IsMemory() || w.Type.IsTuple() && w.Type.FieldType(1).IsMemory() {
if w.Op == ssa.OpVarDef || w.Op == ssa.OpVarKill || w.Op == ssa.OpVarLive {
// these ops are OK
mem = w
continue
}
// We can't delay the nil check past the next store.
break
}
}
// Issue a load which will fault if arg is nil.
p := gc.Prog(arm64.AMOVB)
p.From.Type = obj.TYPE_MEM
......@@ -920,7 +855,7 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
s.SetLineno(b.Line)
switch b.Kind {
case ssa.BlockPlain, ssa.BlockCheck:
case ssa.BlockPlain:
if b.Succs[0].Block() != next {
p := gc.Prog(obj.AJMP)
p.To.Type = obj.TYPE_BRANCH
......
src/cmd/compile/internal/gc/ssa.go
View file @ 3134ab3c
......@@ -3129,20 +3129,13 @@ func (s *state) exprPtr(n *Node, bounded bool, lineno int32) *ssa.Value {
}
// nilCheck generates nil pointer checking code.
// Starts a new block on return, unless nil checks are disabled.
// Used only for automatically inserted nil checks,
// not for user code like 'x != nil'.
func (s *state) nilCheck(ptr *ssa.Value) {
if Disable_checknil != 0 {
return
}
chk := s.newValue2(ssa.OpNilCheck, ssa.TypeVoid, ptr, s.mem())
b := s.endBlock()
b.Kind = ssa.BlockCheck
b.SetControl(chk)
bNext := s.f.NewBlock(ssa.BlockPlain)
b.AddEdgeTo(bNext)
s.startBlock(bNext)
s.newValue2(ssa.OpNilCheck, ssa.TypeVoid, ptr, s.mem())
}
// boundsCheck generates bounds checking code. Checks if 0 <= idx < len, branches to exit if not.
......
src/cmd/compile/internal/mips64/ssa.go
View file @ 3134ab3c
......@@ -638,65 +638,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
gc.Maxarg = v.AuxInt
}
case ssa.OpMIPS64LoweredNilCheck:
// Optimization - if the subsequent block has a load or store
// at the same address, we don't need to issue this instruction.
mem := v.Args[1]
for _, w := range v.Block.Succs[0].Block().Values {
if w.Op == ssa.OpPhi {
if w.Type.IsMemory() {
mem = w
}
continue
}
if len(w.Args) == 0 || !w.Args[len(w.Args)-1].Type.IsMemory() {
// w doesn't use a store - can't be a memory op.
continue
}
if w.Args[len(w.Args)-1] != mem {
v.Fatalf("wrong store after nilcheck v=%s w=%s", v, w)
}
switch w.Op {
case ssa.OpMIPS64MOVBload, ssa.OpMIPS64MOVBUload, ssa.OpMIPS64MOVHload, ssa.OpMIPS64MOVHUload,
ssa.OpMIPS64MOVWload, ssa.OpMIPS64MOVWUload, ssa.OpMIPS64MOVVload,
ssa.OpMIPS64MOVFload, ssa.OpMIPS64MOVDload,
ssa.OpMIPS64MOVBstore, ssa.OpMIPS64MOVHstore, ssa.OpMIPS64MOVWstore, ssa.OpMIPS64MOVVstore,
ssa.OpMIPS64MOVFstore, ssa.OpMIPS64MOVDstore,
ssa.OpMIPS64MOVBstorezero, ssa.OpMIPS64MOVHstorezero, ssa.OpMIPS64MOVWstorezero, ssa.OpMIPS64MOVVstorezero:
// arg0 is ptr, auxint is offset
if w.Args[0] == v.Args[0] && w.Aux == nil && w.AuxInt >= 0 && w.AuxInt < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpMIPS64DUFFZERO, ssa.OpMIPS64LoweredZero:
// arg0 is ptr
if w.Args[0] == v.Args[0] {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpMIPS64LoweredMove:
// arg0 is dst ptr, arg1 is src ptr
if w.Args[0] == v.Args[0] || w.Args[1] == v.Args[0] {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
default:
}
if w.Type.IsMemory() {
if w.Op == ssa.OpVarDef || w.Op == ssa.OpVarKill || w.Op == ssa.OpVarLive {
// these ops are OK
mem = w
continue
}
// We can't delay the nil check past the next store.
break
}
}
// Issue a load which will fault if arg is nil.
p := gc.Prog(mips.AMOVB)
p.From.Type = obj.TYPE_MEM
......@@ -765,7 +706,7 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
s.SetLineno(b.Line)
switch b.Kind {
case ssa.BlockPlain, ssa.BlockCheck:
case ssa.BlockPlain:
if b.Succs[0].Block() != next {
p := gc.Prog(obj.AJMP)
p.To.Type = obj.TYPE_BRANCH
......
src/cmd/compile/internal/ppc64/ssa.go
View file @ 3134ab3c
......@@ -850,64 +850,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
gc.CheckLoweredPhi(v)
case ssa.OpPPC64LoweredNilCheck:
// Optimization - if the subsequent block has a load or store
// at the same address, we don't need to issue this instruction.
mem := v.Args[1]
for _, w := range v.Block.Succs[0].Block().Values {
if w.Op == ssa.OpPhi {
if w.Type.IsMemory() {
mem = w
}
continue
}
if len(w.Args) == 0 || !w.Args[len(w.Args)-1].Type.IsMemory() {
// w doesn't use a store - can't be a memory op.
continue
}
if w.Args[len(w.Args)-1] != mem {
v.Fatalf("wrong store after nilcheck v=%s w=%s", v, w)
}
switch w.Op {
case ssa.OpPPC64MOVBload, ssa.OpPPC64MOVBZload, ssa.OpPPC64MOVHload, ssa.OpPPC64MOVHZload,
ssa.OpPPC64MOVWload, ssa.OpPPC64MOVWZload, ssa.OpPPC64MOVDload, ssa.OpPPC64FMOVDload, ssa.OpPPC64FMOVSload,
ssa.OpPPC64MOVBstore, ssa.OpPPC64MOVHstore, ssa.OpPPC64MOVWstore,
ssa.OpPPC64MOVDstore, ssa.OpPPC64FMOVSstore, ssa.OpPPC64FMOVDstore,
ssa.OpPPC64MOVDstorezero, ssa.OpPPC64MOVWstorezero, ssa.OpPPC64MOVHstorezero, ssa.OpPPC64MOVBstorezero:
// arg0 is ptr, auxint is offset
if w.Args[0] == v.Args[0] && w.Aux == nil && w.AuxInt >= 0 && w.AuxInt < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpPPC64LoweredZero: // ssa.OpPPC64DUFFZERO,
// arg0 is ptr
if w.Args[0] == v.Args[0] {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpPPC64LoweredMove: // ssa.OpPPC64DUFFCOPY,
// arg0 is dst ptr, arg1 is src ptr
if w.Args[0] == v.Args[0] || w.Args[1] == v.Args[0] {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
default:
}
if w.Type.IsMemory() {
if w.Op == ssa.OpVarDef || w.Op == ssa.OpVarKill || w.Op == ssa.OpVarLive {
// these ops are OK
mem = w
continue
}
// We can't delay the nil check past the next store.
break
}
}
// Issue a load which will fault if arg is nil.
p := gc.Prog(ppc64.AMOVB)
p.From.Type = obj.TYPE_MEM
......@@ -972,7 +914,7 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
}
case ssa.BlockPlain, ssa.BlockCheck:
case ssa.BlockPlain:
if b.Succs[0].Block() != next {
p := gc.Prog(obj.AJMP)
p.To.Type = obj.TYPE_BRANCH
......
src/cmd/compile/internal/s390x/ssa.go
View file @ 3134ab3c
......@@ -611,67 +611,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
case ssa.OpS390XFlagEQ, ssa.OpS390XFlagLT, ssa.OpS390XFlagGT:
v.Fatalf("Flag* ops should never make it to codegen %v", v.LongString())
case ssa.OpS390XLoweredNilCheck:
// Optimization - if the subsequent block has a load or store
// at the same address, we don't need to issue this instruction.
mem := v.Args[1]
for _, w := range v.Block.Succs[0].Block().Values {
if w.Op == ssa.OpPhi {
if w.Type.IsMemory() {
mem = w
}
continue
}
if len(w.Args) == 0 || !w.Args[len(w.Args)-1].Type.IsMemory() {
// w doesn't use a store - can't be a memory op.
continue
}
if w.Args[len(w.Args)-1] != mem {
v.Fatalf("wrong store after nilcheck v=%s w=%s", v, w)
}
switch w.Op {
case ssa.OpS390XMOVDload,
ssa.OpS390XMOVBload, ssa.OpS390XMOVHload, ssa.OpS390XMOVWload,
ssa.OpS390XMOVBZload, ssa.OpS390XMOVHZload, ssa.OpS390XMOVWZload,
ssa.OpS390XMOVHBRload, ssa.OpS390XMOVWBRload, ssa.OpS390XMOVDBRload,
ssa.OpS390XMOVBstore, ssa.OpS390XMOVHstore, ssa.OpS390XMOVWstore, ssa.OpS390XMOVDstore,
ssa.OpS390XFMOVSload, ssa.OpS390XFMOVDload,
ssa.OpS390XFMOVSstore, ssa.OpS390XFMOVDstore,
ssa.OpS390XSTMG2, ssa.OpS390XSTMG3, ssa.OpS390XSTMG4,
ssa.OpS390XSTM2, ssa.OpS390XSTM3, ssa.OpS390XSTM4:
if w.Args[0] == v.Args[0] && w.Aux == nil && w.AuxInt >= 0 && w.AuxInt < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpS390XMOVDstoreconst, ssa.OpS390XMOVWstoreconst, ssa.OpS390XMOVHstoreconst, ssa.OpS390XMOVBstoreconst,
ssa.OpS390XCLEAR:
off := ssa.ValAndOff(v.AuxInt).Off()
if w.Args[0] == v.Args[0] && w.Aux == nil && off >= 0 && off < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.OpS390XMVC:
off := ssa.ValAndOff(v.AuxInt).Off()
if (w.Args[0] == v.Args[0] || w.Args[1] == v.Args[0]) && w.Aux == nil && off >= 0 && off < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
}
if w.Type.IsMemory() {
if w.Op == ssa.OpVarDef || w.Op == ssa.OpVarKill || w.Op == ssa.OpVarLive {
// these ops are OK
mem = w
continue
}
// We can't delay the nil check past the next store.
break
}
}
// Issue a load which will fault if the input is nil.
p := gc.Prog(s390x.AMOVBZ)
p.From.Type = obj.TYPE_MEM
......@@ -821,7 +760,7 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
s.SetLineno(b.Line)
switch b.Kind {
case ssa.BlockPlain, ssa.BlockCheck:
case ssa.BlockPlain:
if b.Succs[0].Block() != next {
p := gc.Prog(s390x.ABR)
p.To.Type = obj.TYPE_BRANCH
......
src/cmd/compile/internal/ssa/check.go
View file @ 3134ab3c
......@@ -90,16 +90,6 @@ func checkFunc(f *Func) {
if !b.Control.Type.IsMemory() {
f.Fatalf("defer block %s has non-memory control value %s", b, b.Control.LongString())
}
case BlockCheck:
if len(b.Succs) != 1 {
f.Fatalf("check block %s len(Succs)==%d, want 1", b, len(b.Succs))
}
if b.Control == nil {
f.Fatalf("check block %s has no control value", b)
}
if !b.Control.Type.IsVoid() {
f.Fatalf("check block %s has non-void control value %s", b, b.Control.LongString())
}
case BlockFirst:
if len(b.Succs) != 2 {
f.Fatalf("plain/dead block %s len(Succs)==%d, want 2", b, len(b.Succs))
......
src/cmd/compile/internal/ssa/compile.go
View file @ 3134ab3c
......@@ -276,6 +276,7 @@ var passes = [...]pass{
{name: "likelyadjust", fn: likelyadjust},
{name: "layout", fn: layout, required: true}, // schedule blocks
{name: "schedule", fn: schedule, required: true}, // schedule values
{name: "late nilcheck", fn: nilcheckelim2},
{name: "flagalloc", fn: flagalloc, required: true}, // allocate flags register
{name: "regalloc", fn: regalloc, required: true}, // allocate int & float registers + stack slots
{name: "trim", fn: trim}, // remove empty blocks
......@@ -329,6 +330,8 @@ var passOrder = [...]constraint{
// checkLower must run after lowering & subsequent dead code elim
{"lower", "checkLower"},
{"lowered deadcode", "checkLower"},
// late nilcheck needs instructions to be scheduled.
{"schedule", "late nilcheck"},
// flagalloc needs instructions to be scheduled.
{"schedule", "flagalloc"},
// regalloc needs flags to be allocated first.
......
src/cmd/compile/internal/ssa/deadcode.go
View file @ 3134ab3c
......@@ -68,6 +68,11 @@ func liveValues(f *Func, reachable []bool) []bool {
live[v.ID] = true
q = append(q, v)
}
if v.Type.IsVoid() && !live[v.ID] {
// The only Void ops are nil checks. We must keep these.
live[v.ID] = true
q = append(q, v)
}
}
}
......
src/cmd/compile/internal/ssa/gen/386Ops.go
View file @ 3134ab3c
......@@ -157,8 +157,8 @@ func init() {
{name: "DIVSS", argLength: 2, reg: fp21, asm: "DIVSS", resultInArg0: true}, // fp32 div
{name: "DIVSD", argLength: 2, reg: fp21, asm: "DIVSD", resultInArg0: true}, // fp64 div
{name: "MOVSSload", argLength: 2, reg: fpload, asm: "MOVSS", aux: "SymOff"}, // fp32 load
{name: "MOVSDload", argLength: 2, reg: fpload, asm: "MOVSD", aux: "SymOff"}, // fp64 load
{name: "MOVSSload", argLength: 2, reg: fpload, asm: "MOVSS", aux: "SymOff", faultOnNilArg0: true}, // fp32 load
{name: "MOVSDload", argLength: 2, reg: fpload, asm: "MOVSD", aux: "SymOff", faultOnNilArg0: true}, // fp64 load
{name: "MOVSSconst", reg: fp01, asm: "MOVSS", aux: "Float32", rematerializeable: true}, // fp32 constant
{name: "MOVSDconst", reg: fp01, asm: "MOVSD", aux: "Float64", rematerializeable: true}, // fp64 constant
{name: "MOVSSloadidx1", argLength: 3, reg: fploadidx, asm: "MOVSS", aux: "SymOff"}, // fp32 load indexed by i
......@@ -166,8 +166,8 @@ func init() {
{name: "MOVSDloadidx1", argLength: 3, reg: fploadidx, asm: "MOVSD", aux: "SymOff"}, // fp64 load indexed by i
{name: "MOVSDloadidx8", argLength: 3, reg: fploadidx, asm: "MOVSD", aux: "SymOff"}, // fp64 load indexed by 8*i
{name: "MOVSSstore", argLength: 3, reg: fpstore, asm: "MOVSS", aux: "SymOff"}, // fp32 store
{name: "MOVSDstore", argLength: 3, reg: fpstore, asm: "MOVSD", aux: "SymOff"}, // fp64 store
{name: "MOVSSstore", argLength: 3, reg: fpstore, asm: "MOVSS", aux: "SymOff", faultOnNilArg0: true}, // fp32 store
{name: "MOVSDstore", argLength: 3, reg: fpstore, asm: "MOVSD", aux: "SymOff", faultOnNilArg0: true}, // fp64 store
{name: "MOVSSstoreidx1", argLength: 4, reg: fpstoreidx, asm: "MOVSS", aux: "SymOff"}, // fp32 indexed by i store
{name: "MOVSSstoreidx4", argLength: 4, reg: fpstoreidx, asm: "MOVSS", aux: "SymOff"}, // fp32 indexed by 4i store
{name: "MOVSDstoreidx1", argLength: 4, reg: fpstoreidx, asm: "MOVSD", aux: "SymOff"}, // fp64 indexed by i store
......@@ -323,14 +323,14 @@ func init() {
// Note: LEAL{1,2,4,8} must not have OpSB as either argument.
// auxint+aux == add auxint and the offset of the symbol in aux (if any) to the effective address
{name: "MOVBload", argLength: 2, reg: gpload, asm: "MOVBLZX", aux: "SymOff", typ: "UInt8"}, // load byte from arg0+auxint+aux. arg1=mem. Zero extend.
{name: "MOVBLSXload", argLength: 2, reg: gpload, asm: "MOVBLSX", aux: "SymOff"}, // ditto, sign extend to int32
{name: "MOVWload", argLength: 2, reg: gpload, asm: "MOVWLZX", aux: "SymOff", typ: "UInt16"}, // load 2 bytes from arg0+auxint+aux. arg1=mem. Zero extend.
{name: "MOVWLSXload", argLength: 2, reg: gpload, asm: "MOVWLSX", aux: "SymOff"}, // ditto, sign extend to int32
{name: "MOVLload", argLength: 2, reg: gpload, asm: "MOVL", aux: "SymOff", typ: "UInt32"}, // load 4 bytes from arg0+auxint+aux. arg1=mem. Zero extend.
{name: "MOVBstore", argLength: 3, reg: gpstore, asm: "MOVB", aux: "SymOff", typ: "Mem"}, // store byte in arg1 to arg0+auxint+aux. arg2=mem
{name: "MOVWstore", argLength: 3, reg: gpstore, asm: "MOVW", aux: "SymOff", typ: "Mem"}, // store 2 bytes in arg1 to arg0+auxint+aux. arg2=mem
{name: "MOVLstore", argLength: 3, reg: gpstore, asm: "MOVL", aux: "SymOff", typ: "Mem"}, // store 4 bytes in arg1 to arg0+auxint+aux. arg2=mem
{name: "MOVBload", argLength: 2, reg: gpload, asm: "MOVBLZX", aux: "SymOff", typ: "UInt8", faultOnNilArg0: true}, // load byte from arg0+auxint+aux. arg1=mem. Zero extend.
{name: "MOVBLSXload", argLength: 2, reg: gpload, asm: "MOVBLSX", aux: "SymOff", faultOnNilArg0: true}, // ditto, sign extend to int32
{name: "MOVWload", argLength: 2, reg: gpload, asm: "MOVWLZX", aux: "SymOff", typ: "UInt16", faultOnNilArg0: true}, // load 2 bytes from arg0+auxint+aux. arg1=mem. Zero extend.
{name: "MOVWLSXload", argLength: 2, reg: gpload, asm: "MOVWLSX", aux: "SymOff", faultOnNilArg0: true}, // ditto, sign extend to int32
{name: "MOVLload", argLength: 2, reg: gpload, asm: "MOVL", aux: "SymOff", typ: "UInt32", faultOnNilArg0: true}, // load 4 bytes from arg0+auxint+aux. arg1=mem. Zero extend.
{name: "MOVBstore", argLength: 3, reg: gpstore, asm: "MOVB", aux: "SymOff", typ: "Mem", faultOnNilArg0: true}, // store byte in arg1 to arg0+auxint+aux. arg2=mem
{name: "MOVWstore", argLength: 3, reg: gpstore, asm: "MOVW", aux: "SymOff", typ: "Mem", faultOnNilArg0: true}, // store 2 bytes in arg1 to arg0+auxint+aux. arg2=mem
{name: "MOVLstore", argLength: 3, reg: gpstore, asm: "MOVL", aux: "SymOff", typ: "Mem", faultOnNilArg0: true}, // store 4 bytes in arg1 to arg0+auxint+aux. arg2=mem
// indexed loads/stores
{name: "MOVBloadidx1", argLength: 3, reg: gploadidx, asm: "MOVBLZX", aux: "SymOff"}, // load a byte from arg0+arg1+auxint+aux. arg2=mem
......@@ -349,9 +349,9 @@ func init() {
// For storeconst ops, the AuxInt field encodes both
// the value to store and an address offset of the store.
// Cast AuxInt to a ValAndOff to extract Val and Off fields.
{name: "MOVBstoreconst", argLength: 2, reg: gpstoreconst, asm: "MOVB", aux: "SymValAndOff", typ: "Mem"}, // store low byte of ValAndOff(AuxInt).Val() to arg0+ValAndOff(AuxInt).Off()+aux. arg1=mem
{name: "MOVWstoreconst", argLength: 2, reg: gpstoreconst, asm: "MOVW", aux: "SymValAndOff", typ: "Mem"}, // store low 2 bytes of ...
{name: "MOVLstoreconst", argLength: 2, reg: gpstoreconst, asm: "MOVL", aux: "SymValAndOff", typ: "Mem"}, // store low 4 bytes of ...
{name: "MOVBstoreconst", argLength: 2, reg: gpstoreconst, asm: "MOVB", aux: "SymValAndOff", typ: "Mem", faultOnNilArg0: true}, // store low byte of ValAndOff(AuxInt).Val() to arg0+ValAndOff(AuxInt).Off()+aux. arg1=mem
{name: "MOVWstoreconst", argLength: 2, reg: gpstoreconst, asm: "MOVW", aux: "SymValAndOff", typ: "Mem", faultOnNilArg0: true}, // store low 2 bytes of ...
{name: "MOVLstoreconst", argLength: 2, reg: gpstoreconst, asm: "MOVL", aux: "SymValAndOff", typ: "Mem", faultOnNilArg0: true}, // store low 4 bytes of ...
{name: "MOVBstoreconstidx1", argLength: 3, reg: gpstoreconstidx, asm: "MOVB", aux: "SymValAndOff", typ: "Mem"}, // store low byte of ValAndOff(AuxInt).Val() to arg0+1*arg1+ValAndOff(AuxInt).Off()+aux. arg2=mem
{name: "MOVWstoreconstidx1", argLength: 3, reg: gpstoreconstidx, asm: "MOVW", aux: "SymValAndOff", typ: "Mem"}, // store low 2 bytes of ... arg1 ...
......@@ -439,7 +439,7 @@ func init() {
// use of DX (the closure pointer)
{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("DX")}}},
//arg0=ptr,arg1=mem, returns void. Faults if ptr is nil.
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpsp}}, clobberFlags: true},
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpsp}}, clobberFlags: true, nilCheck: true},
// MOVLconvert converts between pointers and integers.
// We have a special op for this so as to not confuse GC
......
src/cmd/compile/internal/ssa/gen/ARMOps.go
View file @ 3134ab3c
......@@ -314,19 +314,19 @@ func init() {
{name: "MOVWaddr", argLength: 1, reg: regInfo{inputs: []regMask{buildReg("SP") | buildReg("SB")}, outputs: []regMask{gp}}, aux: "SymOff", asm: "MOVW", rematerializeable: true}, // arg0 + auxInt + aux.(*gc.Sym), arg0=SP/SB
{name: "MOVBload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVB", typ: "Int8"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVBUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVBU", typ: "UInt8"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVHload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVH", typ: "Int16"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVHUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVHU", typ: "UInt16"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVWload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVW", typ: "UInt32"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVFload", argLength: 2, reg: fpload, aux: "SymOff", asm: "MOVF", typ: "Float32"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVDload", argLength: 2, reg: fpload, aux: "SymOff", asm: "MOVD", typ: "Float64"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVBstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVB", typ: "Mem"}, // store 1 byte of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVHstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVH", typ: "Mem"}, // store 2 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVWstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVW", typ: "Mem"}, // store 4 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVFstore", argLength: 3, reg: fpstore, aux: "SymOff", asm: "MOVF", typ: "Mem"}, // store 4 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVDstore", argLength: 3, reg: fpstore, aux: "SymOff", asm: "MOVD", typ: "Mem"}, // store 8 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVBload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVB", typ: "Int8", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVBUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVBU", typ: "UInt8", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVHload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVH", typ: "Int16", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVHUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVHU", typ: "UInt16", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVWload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVW", typ: "UInt32", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVFload", argLength: 2, reg: fpload, aux: "SymOff", asm: "MOVF", typ: "Float32", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVDload", argLength: 2, reg: fpload, aux: "SymOff", asm: "MOVD", typ: "Float64", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVBstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVB", typ: "Mem", faultOnNilArg0: true}, // store 1 byte of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVHstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVH", typ: "Mem", faultOnNilArg0: true}, // store 2 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVWstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVW", typ: "Mem", faultOnNilArg0: true}, // store 4 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVFstore", argLength: 3, reg: fpstore, aux: "SymOff", asm: "MOVF", typ: "Mem", faultOnNilArg0: true}, // store 4 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVDstore", argLength: 3, reg: fpstore, aux: "SymOff", asm: "MOVD", typ: "Mem", faultOnNilArg0: true}, // store 8 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVWloadidx", argLength: 3, reg: gp2load, asm: "MOVW"}, // load from arg0 + arg1. arg2=mem
{name: "MOVWloadshiftLL", argLength: 3, reg: gp2load, asm: "MOVW", aux: "Int32"}, // load from arg0 + arg1<<auxInt. arg2=mem
......@@ -370,7 +370,7 @@ func init() {
{name: "CALLinter", argLength: 2, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "Int64", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
// pseudo-ops
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}}, // panic if arg0 is nil. arg1=mem.
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}, nilCheck: true}, // panic if arg0 is nil. arg1=mem.
{name: "Equal", argLength: 1, reg: readflags}, // bool, true flags encode x==y false otherwise.
{name: "NotEqual", argLength: 1, reg: readflags}, // bool, true flags encode x!=y false otherwise.
......@@ -397,6 +397,7 @@ func init() {
inputs: []regMask{buildReg("R1"), buildReg("R0")},
clobbers: buildReg("R1"),
},
faultOnNilArg0: true,
},
// duffcopy (must be 4-byte aligned)
......@@ -413,6 +414,8 @@ func init() {
inputs: []regMask{buildReg("R2"), buildReg("R1")},
clobbers: buildReg("R0 R1 R2"),
},
faultOnNilArg0: true,
faultOnNilArg1: true,
},
// large or unaligned zeroing
......@@ -433,6 +436,7 @@ func init() {
clobbers: buildReg("R1"),
},
clobberFlags: true,
faultOnNilArg0: true,
},
// large or unaligned move
......@@ -454,6 +458,8 @@ func init() {
clobbers: buildReg("R1 R2"),
},
clobberFlags: true,
faultOnNilArg0: true,
faultOnNilArg1: true,
},
// Scheduler ensures LoweredGetClosurePtr occurs only in entry block,
......
src/cmd/compile/internal/ssa/gen/MIPS64Ops.go
View file @ 3134ab3c
......@@ -219,27 +219,27 @@ func init() {
{name: "MOVVaddr", argLength: 1, reg: regInfo{inputs: []regMask{buildReg("SP") | buildReg("SB")}, outputs: []regMask{gp}}, aux: "SymOff", asm: "MOVV", rematerializeable: true}, // arg0 + auxInt + aux.(*gc.Sym), arg0=SP/SB
{name: "MOVBload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVB", typ: "Int8"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVBUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVBU", typ: "UInt8"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVHload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVH", typ: "Int16"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVHUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVHU", typ: "UInt16"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVWload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVW", typ: "Int32"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVWUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVWU", typ: "UInt32"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVVload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVV", typ: "UInt64"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVFload", argLength: 2, reg: fpload, aux: "SymOff", asm: "MOVF", typ: "Float32"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVDload", argLength: 2, reg: fpload, aux: "SymOff", asm: "MOVD", typ: "Float64"}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVBstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVB", typ: "Mem"}, // store 1 byte of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVHstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVH", typ: "Mem"}, // store 2 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVWstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVW", typ: "Mem"}, // store 4 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVVstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVV", typ: "Mem"}, // store 8 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVFstore", argLength: 3, reg: fpstore, aux: "SymOff", asm: "MOVF", typ: "Mem"}, // store 4 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVDstore", argLength: 3, reg: fpstore, aux: "SymOff", asm: "MOVD", typ: "Mem"}, // store 8 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVBstorezero", argLength: 2, reg: gpstore0, aux: "SymOff", asm: "MOVB", typ: "Mem"}, // store 1 byte of zero to arg0 + auxInt + aux. arg1=mem.
{name: "MOVHstorezero", argLength: 2, reg: gpstore0, aux: "SymOff", asm: "MOVH", typ: "Mem"}, // store 2 bytes of zero to arg0 + auxInt + aux. arg1=mem.
{name: "MOVWstorezero", argLength: 2, reg: gpstore0, aux: "SymOff", asm: "MOVW", typ: "Mem"}, // store 4 bytes of zero to arg0 + auxInt + aux. arg1=mem.
{name: "MOVVstorezero", argLength: 2, reg: gpstore0, aux: "SymOff", asm: "MOVV", typ: "Mem"}, // store 8 bytes of zero to arg0 + auxInt + aux. ar12=mem.
{name: "MOVBload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVB", typ: "Int8", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVBUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVBU", typ: "UInt8", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVHload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVH", typ: "Int16", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVHUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVHU", typ: "UInt16", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVWload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVW", typ: "Int32", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVWUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVWU", typ: "UInt32", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVVload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVV", typ: "UInt64", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVFload", argLength: 2, reg: fpload, aux: "SymOff", asm: "MOVF", typ: "Float32", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVDload", argLength: 2, reg: fpload, aux: "SymOff", asm: "MOVD", typ: "Float64", faultOnNilArg0: true}, // load from arg0 + auxInt + aux. arg1=mem.
{name: "MOVBstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVB", typ: "Mem", faultOnNilArg0: true}, // store 1 byte of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVHstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVH", typ: "Mem", faultOnNilArg0: true}, // store 2 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVWstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVW", typ: "Mem", faultOnNilArg0: true}, // store 4 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVVstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVV", typ: "Mem", faultOnNilArg0: true}, // store 8 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVFstore", argLength: 3, reg: fpstore, aux: "SymOff", asm: "MOVF", typ: "Mem", faultOnNilArg0: true}, // store 4 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVDstore", argLength: 3, reg: fpstore, aux: "SymOff", asm: "MOVD", typ: "Mem", faultOnNilArg0: true}, // store 8 bytes of arg1 to arg0 + auxInt + aux. arg2=mem.
{name: "MOVBstorezero", argLength: 2, reg: gpstore0, aux: "SymOff", asm: "MOVB", typ: "Mem", faultOnNilArg0: true}, // store 1 byte of zero to arg0 + auxInt + aux. arg1=mem.
{name: "MOVHstorezero", argLength: 2, reg: gpstore0, aux: "SymOff", asm: "MOVH", typ: "Mem", faultOnNilArg0: true}, // store 2 bytes of zero to arg0 + auxInt + aux. arg1=mem.
{name: "MOVWstorezero", argLength: 2, reg: gpstore0, aux: "SymOff", asm: "MOVW", typ: "Mem", faultOnNilArg0: true}, // store 4 bytes of zero to arg0 + auxInt + aux. arg1=mem.
{name: "MOVVstorezero", argLength: 2, reg: gpstore0, aux: "SymOff", asm: "MOVV", typ: "Mem", faultOnNilArg0: true}, // store 8 bytes of zero to arg0 + auxInt + aux. ar12=mem.
// conversions
{name: "MOVBreg", argLength: 1, reg: gp11, asm: "MOVB"}, // move from arg0, sign-extended from byte
......@@ -284,6 +284,7 @@ func init() {
inputs: []regMask{gp},
clobbers: buildReg("R1"),
},
faultOnNilArg0: true,
},
// large or unaligned zeroing
......@@ -305,6 +306,7 @@ func init() {
clobbers: buildReg("R1"),
},
clobberFlags: true,
faultOnNilArg0: true,
},
// large or unaligned move
......@@ -329,10 +331,12 @@ func init() {
clobbers: buildReg("R1 R2"),
},
clobberFlags: true,
faultOnNilArg0: true,
faultOnNilArg1: true,
},
// pseudo-ops
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}}, // panic if arg0 is nil. arg1=mem.
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}, nilCheck: true}, // panic if arg0 is nil. arg1=mem.
{name: "FPFlagTrue", argLength: 1, reg: readflags}, // bool, true if FP flag is true
{name: "FPFlagFalse", argLength: 1, reg: readflags}, // bool, true if FP flag is false
......
src/cmd/compile/internal/ssa/gen/PPC64Ops.go
View file @ 3134ab3c
......@@ -233,27 +233,27 @@ func init() {
{name: "MOVHZreg", argLength: 1, reg: gp11, asm: "MOVHZ", typ: "Int64"}, // zero extend uint16 to uint64
{name: "MOVWreg", argLength: 1, reg: gp11, asm: "MOVW", typ: "Int64"}, // sign extend int32 to int64
{name: "MOVWZreg", argLength: 1, reg: gp11, asm: "MOVWZ", typ: "Int64"}, // zero extend uint32 to uint64
{name: "MOVBload", argLength: 2, reg: gpload, asm: "MOVB", aux: "SymOff", typ: "Int8"}, // sign extend int8 to int64
{name: "MOVBZload", argLength: 2, reg: gpload, asm: "MOVBZ", aux: "SymOff", typ: "UInt8"}, // zero extend uint8 to uint64
{name: "MOVHload", argLength: 2, reg: gpload, asm: "MOVH", aux: "SymOff", typ: "Int16"}, // sign extend int16 to int64
{name: "MOVHZload", argLength: 2, reg: gpload, asm: "MOVHZ", aux: "SymOff", typ: "UInt16"}, // zero extend uint16 to uint64
{name: "MOVWload", argLength: 2, reg: gpload, asm: "MOVW", aux: "SymOff", typ: "Int32"}, // sign extend int32 to int64
{name: "MOVWZload", argLength: 2, reg: gpload, asm: "MOVWZ", aux: "SymOff", typ: "UInt32"}, // zero extend uint32 to uint64
{name: "MOVDload", argLength: 2, reg: gpload, asm: "MOVD", aux: "SymOff", typ: "Int64"},
{name: "FMOVDload", argLength: 2, reg: fpload, asm: "FMOVD", aux: "SymOff", typ: "Float64"},
{name: "FMOVSload", argLength: 2, reg: fpload, asm: "FMOVS", aux: "SymOff", typ: "Float32"},
{name: "MOVBstore", argLength: 3, reg: gpstore, asm: "MOVB", aux: "SymOff", typ: "Mem"},
{name: "MOVHstore", argLength: 3, reg: gpstore, asm: "MOVH", aux: "SymOff", typ: "Mem"},
{name: "MOVWstore", argLength: 3, reg: gpstore, asm: "MOVW", aux: "SymOff", typ: "Mem"},
{name: "MOVDstore", argLength: 3, reg: gpstore, asm: "MOVD", aux: "SymOff", typ: "Mem"},
{name: "FMOVDstore", argLength: 3, reg: fpstore, asm: "FMOVD", aux: "SymOff", typ: "Mem"},
{name: "FMOVSstore", argLength: 3, reg: fpstore, asm: "FMOVS", aux: "SymOff", typ: "Mem"},
{name: "MOVBstorezero", argLength: 2, reg: gpstorezero, asm: "MOVB", aux: "SymOff", typ: "Mem"}, // store zero byte to arg0+aux. arg1=mem
{name: "MOVHstorezero", argLength: 2, reg: gpstorezero, asm: "MOVH", aux: "SymOff", typ: "Mem"}, // store zero 2 bytes to ...
{name: "MOVWstorezero", argLength: 2, reg: gpstorezero, asm: "MOVW", aux: "SymOff", typ: "Mem"}, // store zero 4 bytes to ...
{name: "MOVDstorezero", argLength: 2, reg: gpstorezero, asm: "MOVD", aux: "SymOff", typ: "Mem"}, // store zero 8 bytes to ...
{name: "MOVBload", argLength: 2, reg: gpload, asm: "MOVB", aux: "SymOff", typ: "Int8", faultOnNilArg0: true}, // sign extend int8 to int64
{name: "MOVBZload", argLength: 2, reg: gpload, asm: "MOVBZ", aux: "SymOff", typ: "UInt8", faultOnNilArg0: true}, // zero extend uint8 to uint64
{name: "MOVHload", argLength: 2, reg: gpload, asm: "MOVH", aux: "SymOff", typ: "Int16", faultOnNilArg0: true}, // sign extend int16 to int64
{name: "MOVHZload", argLength: 2, reg: gpload, asm: "MOVHZ", aux: "SymOff", typ: "UInt16", faultOnNilArg0: true}, // zero extend uint16 to uint64
{name: "MOVWload", argLength: 2, reg: gpload, asm: "MOVW", aux: "SymOff", typ: "Int32", faultOnNilArg0: true}, // sign extend int32 to int64
{name: "MOVWZload", argLength: 2, reg: gpload, asm: "MOVWZ", aux: "SymOff", typ: "UInt32", faultOnNilArg0: true}, // zero extend uint32 to uint64
{name: "MOVDload", argLength: 2, reg: gpload, asm: "MOVD", aux: "SymOff", typ: "Int64", faultOnNilArg0: true},
{name: "FMOVDload", argLength: 2, reg: fpload, asm: "FMOVD", aux: "SymOff", typ: "Float64", faultOnNilArg0: true},
{name: "FMOVSload", argLength: 2, reg: fpload, asm: "FMOVS", aux: "SymOff", typ: "Float32", faultOnNilArg0: true},
{name: "MOVBstore", argLength: 3, reg: gpstore, asm: "MOVB", aux: "SymOff", typ: "Mem", faultOnNilArg0: true},
{name: "MOVHstore", argLength: 3, reg: gpstore, asm: "MOVH", aux: "SymOff", typ: "Mem", faultOnNilArg0: true},
{name: "MOVWstore", argLength: 3, reg: gpstore, asm: "MOVW", aux: "SymOff", typ: "Mem", faultOnNilArg0: true},
{name: "MOVDstore", argLength: 3, reg: gpstore, asm: "MOVD", aux: "SymOff", typ: "Mem", faultOnNilArg0: true},
{name: "FMOVDstore", argLength: 3, reg: fpstore, asm: "FMOVD", aux: "SymOff", typ: "Mem", faultOnNilArg0: true},
{name: "FMOVSstore", argLength: 3, reg: fpstore, asm: "FMOVS", aux: "SymOff", typ: "Mem", faultOnNilArg0: true},
{name: "MOVBstorezero", argLength: 2, reg: gpstorezero, asm: "MOVB", aux: "SymOff", typ: "Mem", faultOnNilArg0: true}, // store zero byte to arg0+aux. arg1=mem
{name: "MOVHstorezero", argLength: 2, reg: gpstorezero, asm: "MOVH", aux: "SymOff", typ: "Mem", faultOnNilArg0: true}, // store zero 2 bytes to ...
{name: "MOVWstorezero", argLength: 2, reg: gpstorezero, asm: "MOVW", aux: "SymOff", typ: "Mem", faultOnNilArg0: true}, // store zero 4 bytes to ...
{name: "MOVDstorezero", argLength: 2, reg: gpstorezero, asm: "MOVD", aux: "SymOff", typ: "Mem", faultOnNilArg0: true}, // store zero 8 bytes to ...
{name: "MOVDaddr", argLength: 1, reg: regInfo{inputs: []regMask{sp | sb}, outputs: []regMask{gp}}, aux: "SymOff", asm: "MOVD", rematerializeable: true}, // arg0 + auxInt + aux.(*gc.Sym), arg0=SP/SB
......@@ -290,7 +290,7 @@ func init() {
{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{ctxt}}},
//arg0=ptr,arg1=mem, returns void. Faults if ptr is nil.
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gp | sp | sb}, clobbers: tmp}, clobberFlags: true},
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gp | sp | sb}, clobbers: tmp}, clobberFlags: true, nilCheck: true},
// Convert pointer to integer, takes a memory operand for ordering.
{name: "MOVDconvert", argLength: 2, reg: gp11, asm: "MOVD"},
......@@ -320,6 +320,7 @@ func init() {
},
clobberFlags: true,
typ: "Mem",
faultOnNilArg0: true,
},
// large or unaligned move
......@@ -344,6 +345,8 @@ func init() {
},
clobberFlags: true,
typ: "Mem",
faultOnNilArg0: true,
faultOnNilArg1: true,
},
// (InvertFlags (CMP a b)) == (CMP b a)
......
src/cmd/compile/internal/ssa/gen/generic.rules
View file @ 3134ab3c
......@@ -770,7 +770,7 @@
(ConstNil <config.fe.TypeBytePtr()>)
(ConstNil <config.fe.TypeBytePtr()>))
(Check (NilCheck (GetG _) _) next) -> (Plain nil next)
(NilCheck (GetG mem) mem) -> mem
(If (Not cond) yes no) -> (If cond no yes)
(If (ConstBool [c]) yes no) && c == 1 -> (First nil yes no)
......@@ -951,16 +951,20 @@
(Sqrt (Const64F [c])) -> (Const64F [f2i(math.Sqrt(i2f(c)))])
// recognize runtime.newobject and don't Zero/Nilcheck it
(Zero (Load (OffPtr [c] (SP)) mem:(StaticCall {sym} _)) mem2)
(Zero (Load (OffPtr [c] (SP)) mem) mem)
&& mem.Op == OpStaticCall
&& isSameSym(mem.Aux, "runtime.newobject")
&& c == config.ctxt.FixedFrameSize() + config.PtrSize // offset of return value
&& mem2 == mem
&& isSameSym(sym, "runtime.newobject")
-> mem
(Check (NilCheck (Load (OffPtr [c] (SP)) mem:(StaticCall {sym} _)) _) succ)
&& c == config.ctxt.FixedFrameSize() + config.PtrSize // offset of return value
&& isSameSym(sym, "runtime.newobject")
-> (Plain nil succ)
(Check (NilCheck (OffPtr (Load (OffPtr [c] (SP)) mem:(StaticCall {sym} _))) _) succ)
&& c == config.ctxt.FixedFrameSize() + config.PtrSize // offset of return value
&& isSameSym(sym, "runtime.newobject")
-> (Plain nil succ)
// nil checks just need to rewrite to something useless.
// they will be deadcode eliminated soon afterwards.
//(NilCheck (Load (OffPtr [c] (SP)) mem) mem)
// && mem.Op == OpStaticCall
// && isSameSym(mem.Aux, "runtime.newobject")
// && c == config.ctxt.FixedFrameSize() + config.PtrSize // offset of return value
// -> (Invalid)
//(NilCheck (OffPtr (Load (OffPtr [c] (SP)) mem)) mem)
// && mem.Op == OpStaticCall
// && isSameSym(mem.Aux, "runtime.newobject")
// && c == config.ctxt.FixedFrameSize() + config.PtrSize // offset of return value
// -> (Invalid)
src/cmd/compile/internal/ssa/gen/genericOps.go
View file @ 3134ab3c
......@@ -303,6 +303,7 @@ var genericOps = []opData{
{name: "SP"}, // stack pointer
{name: "SB", typ: "Uintptr"}, // static base pointer (a.k.a. globals pointer)
{name: "Func", aux: "Sym"}, // entry address of a function
{name: "Invalid"}, // unused value
// Memory operations
{name: "Load", argLength: 2}, // Load from arg0. arg1=memory
......@@ -354,7 +355,7 @@ var genericOps = []opData{
{name: "IsNonNil", argLength: 1, typ: "Bool"}, // arg0 != nil
{name: "IsInBounds", argLength: 2, typ: "Bool"}, // 0 <= arg0 < arg1. arg1 is guaranteed >= 0.
{name: "IsSliceInBounds", argLength: 2, typ: "Bool"}, // 0 <= arg0 <= arg1. arg1 is guaranteed >= 0.
{name: "NilCheck", argLength: 2, typ: "Void"}, // arg0=ptr, arg1=mem. Panics if arg0 is nil, returns void.
{name: "NilCheck", argLength: 2, typ: "Void"}, // arg0=ptr, arg1=mem. Panics if arg0 is nil. Returns void.
// Pseudo-ops
{name: "GetG", argLength: 1}, // runtime.getg() (read g pointer). arg0=mem
......@@ -476,7 +477,6 @@ var genericBlocks = []blockData{
{name: "Plain"}, // a single successor
{name: "If"}, // 2 successors, if control goto Succs[0] else goto Succs[1]
{name: "Defer"}, // 2 successors, Succs[0]=defer queued, Succs[1]=defer recovered. control is call op (of memory type)
{name: "Check"}, // 1 successor, control is nilcheck op (of void type)
{name: "Ret"}, // no successors, control value is memory result
{name: "RetJmp"}, // no successors, jumps to b.Aux.(*gc.Sym)
{name: "Exit"}, // no successors, control value generates a panic
......
src/cmd/compile/internal/ssa/gen/main.go
View file @ 3134ab3c
......@@ -47,6 +47,9 @@ type opData struct {
resultNotInArgs bool // outputs must not be allocated to the same registers as inputs
clobberFlags bool // this op clobbers flags register
call bool // is a function call
nilCheck bool // this op is a nil check on arg0
faultOnNilArg0 bool // this op will fault if arg0 is nil (and aux encodes a small offset)
faultOnNilArg1 bool // this op will fault if arg1 is nil (and aux encodes a small offset)
}
type blockData struct {
......@@ -126,10 +129,13 @@ func genOp() {
// generate Op* declarations
fmt.Fprintln(w, "const (")
fmt.Fprintln(w, "OpInvalid Op = iota")
fmt.Fprintln(w, "OpInvalid Op = iota") // make sure OpInvalid is 0.
for _, a := range archs {
fmt.Fprintln(w)
for _, v := range a.ops {
if v.name == "Invalid" {
continue
}
fmt.Fprintf(w, "Op%s%s\n", a.Name(), v.name)
}
}
......@@ -143,6 +149,9 @@ func genOp() {
pkg := path.Base(a.pkg)
for _, v := range a.ops {
if v.name == "Invalid" {
continue
}
fmt.Fprintln(w, "{")
fmt.Fprintf(w, "name:\"%s\",\n", v.name)
......@@ -179,6 +188,21 @@ func genOp() {
if v.call {
fmt.Fprintln(w, "call: true,")
}
if v.nilCheck {
fmt.Fprintln(w, "nilCheck: true,")
}
if v.faultOnNilArg0 {
fmt.Fprintln(w, "faultOnNilArg0: true,")
if v.aux != "SymOff" && v.aux != "SymValAndOff" && v.aux != "Int64" && v.aux != "" {
log.Fatalf("faultOnNilArg0 with aux %s not allowed", v.aux)
}
}
if v.faultOnNilArg1 {
fmt.Fprintln(w, "faultOnNilArg1: true,")
if v.aux != "SymOff" && v.aux != "SymValAndOff" && v.aux != "Int64" && v.aux != "" {
log.Fatalf("faultOnNilArg1 with aux %s not allowed", v.aux)
}
}
if a.name == "generic" {
fmt.Fprintln(w, "generic:true,")
fmt.Fprintln(w, "},") // close op
......
src/cmd/compile/internal/ssa/nilcheck.go
View file @ 3134ab3c
......@@ -5,6 +5,7 @@
package ssa
// nilcheckelim eliminates unnecessary nil checks.
// runs on machine-independent code.
func nilcheckelim(f *Func) {
// A nil check is redundant if the same nil check was successful in a
// dominating block. The efficacy of this pass depends heavily on the
......@@ -26,14 +27,13 @@ func nilcheckelim(f *Func) {
type walkState int
const (
Work walkState = iota // clear nil check if we should and traverse to dominees regardless
RecPtr // record the pointer as being nil checked
ClearPtr
Work walkState = iota // process nil checks and traverse to dominees
ClearPtr // forget the fact that ptr is nil
)
type bp struct {
block *Block // block, or nil in RecPtr/ClearPtr state
ptr *Value // if non-nil, ptr that is to be set/cleared in RecPtr/ClearPtr state
block *Block // block, or nil in ClearPtr state
ptr *Value // if non-nil, ptr that is to be cleared in ClearPtr state
op walkState
}
......@@ -76,54 +76,62 @@ func nilcheckelim(f *Func) {
switch node.op {
case Work:
checked := checkedptr(node.block) // ptr being checked for nil/non-nil
nonnil := nonnilptr(node.block) // ptr that is non-nil due to this blocks pred
b := node.block
if checked != nil {
// already have a nilcheck in the dominator path, or this block is a success
// block for the same value it is checking
if nonNilValues[checked.ID] || checked == nonnil {
// Eliminate the nil check.
// The deadcode pass will remove vestigial values,
// and the fuse pass will join this block with its successor.
// First, see if we're dominated by an explicit nil check.
if len(b.Preds) == 1 {
p := b.Preds[0].b
if p.Kind == BlockIf && p.Control.Op == OpIsNonNil && p.Succs[0].b == b {
ptr := p.Control.Args[0]
if !nonNilValues[ptr.ID] {
nonNilValues[ptr.ID] = true
work = append(work, bp{op: ClearPtr, ptr: ptr})
}
}
}
// Next, process values in the block.
i := 0
for _, v := range b.Values {
b.Values[i] = v
i++
switch v.Op {
case OpIsNonNil:
ptr := v.Args[0]
if nonNilValues[ptr.ID] {
// This is a redundant explicit nil check.
v.reset(OpConstBool)
v.AuxInt = 1 // true
}
case OpNilCheck:
ptr := v.Args[0]
if nonNilValues[ptr.ID] {
// This is a redundant implicit nil check.
// Logging in the style of the former compiler -- and omit line 1,
// which is usually in generated code.
if f.Config.Debug_checknil() && node.block.Control.Line > 1 {
f.Config.Warnl(node.block.Control.Line, "removed nil check")
if f.Config.Debug_checknil() && v.Line > 1 {
f.Config.Warnl(v.Line, "removed nil check")
}
switch node.block.Kind {
case BlockIf:
node.block.Kind = BlockFirst
node.block.SetControl(nil)
case BlockCheck:
node.block.Kind = BlockPlain
node.block.SetControl(nil)
default:
f.Fatalf("bad block kind in nilcheck %s", node.block.Kind)
v.reset(OpUnknown)
i--
continue
}
// Record the fact that we know ptr is non nil, and remember to
// undo that information when this dominator subtree is done.
nonNilValues[ptr.ID] = true
work = append(work, bp{op: ClearPtr, ptr: ptr})
}
}
if nonnil != nil && !nonNilValues[nonnil.ID] {
// this is a new nilcheck so add a ClearPtr node to clear the
// ptr from the map of nil checks once we traverse
// back up the tree
work = append(work, bp{op: ClearPtr, ptr: nonnil})
for j := i; j < len(b.Values); j++ {
b.Values[j] = nil
}
b.Values = b.Values[:i]
// add all dominated blocks to the work list
// Add all dominated blocks to the work list.
for _, w := range domTree[node.block.ID] {
work = append(work, bp{block: w})
work = append(work, bp{op: Work, block: w})
}
if nonnil != nil && !nonNilValues[nonnil.ID] {
work = append(work, bp{op: RecPtr, ptr: nonnil})
}
case RecPtr:
nonNilValues[node.ptr.ID] = true
continue
case ClearPtr:
nonNilValues[node.ptr.ID] = false
continue
......@@ -131,31 +139,86 @@ func nilcheckelim(f *Func) {
}
}
// checkedptr returns the Value, if any,
// that is used in a nil check in b's Control op.
func checkedptr(b *Block) *Value {
if b.Kind == BlockCheck {
return b.Control.Args[0]
// All platforms are guaranteed to fault if we load/store to anything smaller than this address.
const minZeroPage = 4096
// nilcheckelim2 eliminates unnecessary nil checks.
// Runs after lowering and scheduling.
func nilcheckelim2(f *Func) {
unnecessary := f.newSparseSet(f.NumValues())
defer f.retSparseSet(unnecessary)
for _, b := range f.Blocks {
// Walk the block backwards. Find instructions that will fault if their
// input pointer is nil. Remove nil checks on those pointers, as the
// faulting instruction effectively does the nil check for free.
unnecessary.clear()
for i := len(b.Values) - 1; i >= 0; i-- {
v := b.Values[i]
if opcodeTable[v.Op].nilCheck && unnecessary.contains(v.Args[0].ID) {
if f.Config.Debug_checknil() && int(v.Line) > 1 {
f.Config.Warnl(v.Line, "removed nil check")
}
v.reset(OpUnknown)
continue
}
if b.Kind == BlockIf && b.Control.Op == OpIsNonNil {
return b.Control.Args[0]
if v.Type.IsMemory() || v.Type.IsTuple() && v.Type.FieldType(1).IsMemory() {
if v.Op == OpVarDef || v.Op == OpVarKill || v.Op == OpVarLive {
// These ops don't really change memory.
continue
}
// This op changes memory. Any faulting instruction after v that
// we've recorded in the unnecessary map is now obsolete.
unnecessary.clear()
}
return nil
}
// nonnilptr returns the Value, if any,
// that is non-nil due to b being the successor block
// of an OpIsNonNil or OpNilCheck block for the value and having a single
// predecessor.
func nonnilptr(b *Block) *Value {
if len(b.Preds) == 1 {
bp := b.Preds[0].b
if bp.Kind == BlockCheck {
return bp.Control.Args[0]
// Find any pointers that this op is guaranteed to fault on if nil.
var ptrstore [2]*Value
ptrs := ptrstore[:0]
if opcodeTable[v.Op].faultOnNilArg0 {
ptrs = append(ptrs, v.Args[0])
}
if opcodeTable[v.Op].faultOnNilArg1 {
ptrs = append(ptrs, v.Args[1])
}
for _, ptr := range ptrs {
// Check to make sure the offset is small.
switch opcodeTable[v.Op].auxType {
case auxSymOff:
if v.Aux != nil || v.AuxInt < 0 || v.AuxInt >= minZeroPage {
continue
}
case auxSymValAndOff:
off := ValAndOff(v.AuxInt).Off()
if v.Aux != nil || off < 0 || off >= minZeroPage {
continue
}
if bp.Kind == BlockIf && bp.Control.Op == OpIsNonNil && bp.Succs[0].b == b {
return bp.Control.Args[0]
case auxInt64:
// ARM uses this auxType for duffcopy/duffzero/alignment info.
// It does not affect the effective address.
case auxNone:
// offset is zero.
default:
v.Fatalf("can't handle aux %s (type %d) yet\n", v.auxString(), int(opcodeTable[v.Op].auxType))
}
// This instruction is guaranteed to fault if ptr is nil.
// Any previous nil check op is unnecessary.
unnecessary.add(ptr.ID)
}
}
// Remove values we've clobbered with OpUnknown.
i := 0
for _, v := range b.Values {
if v.Op != OpUnknown {
b.Values[i] = v
i++
}
}
for j := i; j < len(b.Values); j++ {
b.Values[j] = nil
}
b.Values = b.Values[:i]
// TODO: if b.Kind == BlockPlain, start the analysis in the subsequent block to find
// more unnecessary nil checks. Would fix test/nilptr3_ssa.go:157.
}
return nil
}
src/cmd/compile/internal/ssa/op.go
View file @ 3134ab3c
......@@ -30,6 +30,9 @@ type opInfo struct {
resultNotInArgs bool // outputs must not be allocated to the same registers as inputs
clobberFlags bool // this op clobbers flags register
call bool // is a function call
nilCheck bool // this op is a nil check on arg0
faultOnNilArg0 bool // this op will fault if arg0 is nil (and aux encodes a small offset)
faultOnNilArg1 bool // this op will fault if arg1 is nil (and aux encodes a small offset)
}
type inputInfo struct {
......
src/cmd/compile/internal/ssa/opGen.go
View file @ 3134ab3c
This diff is collapsed.
src/cmd/compile/internal/ssa/rewritegeneric.go
View file @ 3134ab3c
......@@ -232,6 +232,8 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
return rewriteValuegeneric_OpNeqPtr(v, config)
case OpNeqSlice:
return rewriteValuegeneric_OpNeqSlice(v, config)
case OpNilCheck:
return rewriteValuegeneric_OpNilCheck(v, config)
case OpNot:
return rewriteValuegeneric_OpNot(v, config)
case OpOffPtr:
......@@ -6358,6 +6360,28 @@ func rewriteValuegeneric_OpNeqSlice(v *Value, config *Config) bool {
return true
}
}
func rewriteValuegeneric_OpNilCheck(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (NilCheck (GetG mem) mem)
// cond:
// result: mem
for {
v_0 := v.Args[0]
if v_0.Op != OpGetG {
break
}
mem := v_0.Args[0]
if mem != v.Args[1] {
break
}
v.reset(OpCopy)
v.Type = mem.Type
v.AddArg(mem)
return true
}
return false
}
func rewriteValuegeneric_OpNot(v *Value, config *Config) bool {
b := v.Block
_ = b
......@@ -11611,8 +11635,8 @@ func rewriteValuegeneric_OpXor8(v *Value, config *Config) bool {
func rewriteValuegeneric_OpZero(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (Zero (Load (OffPtr [c] (SP)) mem:(StaticCall {sym} _)) mem2)
// cond: c == config.ctxt.FixedFrameSize() + config.PtrSize && mem2 == mem && isSameSym(sym, "runtime.newobject")
// match: (Zero (Load (OffPtr [c] (SP)) mem) mem)
// cond: mem.Op == OpStaticCall && isSameSym(mem.Aux, "runtime.newobject") && c == config.ctxt.FixedFrameSize() + config.PtrSize
// result: mem
for {
v_0 := v.Args[0]
......@@ -11629,12 +11653,10 @@ func rewriteValuegeneric_OpZero(v *Value, config *Config) bool {
break
}
mem := v_0.Args[1]
if mem.Op != OpStaticCall {
if mem != v.Args[1] {
break
}
sym := mem.Aux
mem2 := v.Args[1]
if !(c == config.ctxt.FixedFrameSize()+config.PtrSize && mem2 == mem && isSameSym(sym, "runtime.newobject")) {
if !(mem.Op == OpStaticCall && isSameSym(mem.Aux, "runtime.newobject") && c == config.ctxt.FixedFrameSize()+config.PtrSize) {
break
}
v.reset(OpCopy)
......@@ -11646,99 +11668,6 @@ func rewriteValuegeneric_OpZero(v *Value, config *Config) bool {
}
func rewriteBlockgeneric(b *Block, config *Config) bool {
switch b.Kind {
case BlockCheck:
// match: (Check (NilCheck (GetG _) _) next)
// cond:
// result: (Plain nil next)
for {
v := b.Control
if v.Op != OpNilCheck {
break
}
v_0 := v.Args[0]
if v_0.Op != OpGetG {
break
}
next := b.Succs[0]
b.Kind = BlockPlain
b.SetControl(nil)
_ = next
return true
}
// match: (Check (NilCheck (Load (OffPtr [c] (SP)) mem:(StaticCall {sym} _)) _) succ)
// cond: c == config.ctxt.FixedFrameSize() + config.PtrSize && isSameSym(sym, "runtime.newobject")
// result: (Plain nil succ)
for {
v := b.Control
if v.Op != OpNilCheck {
break
}
v_0 := v.Args[0]
if v_0.Op != OpLoad {
break
}
v_0_0 := v_0.Args[0]
if v_0_0.Op != OpOffPtr {
break
}
c := v_0_0.AuxInt
v_0_0_0 := v_0_0.Args[0]
if v_0_0_0.Op != OpSP {
break
}
mem := v_0.Args[1]
if mem.Op != OpStaticCall {
break
}
sym := mem.Aux
succ := b.Succs[0]
if !(c == config.ctxt.FixedFrameSize()+config.PtrSize && isSameSym(sym, "runtime.newobject")) {
break
}
b.Kind = BlockPlain
b.SetControl(nil)
_ = succ
return true
}
// match: (Check (NilCheck (OffPtr (Load (OffPtr [c] (SP)) mem:(StaticCall {sym} _))) _) succ)
// cond: c == config.ctxt.FixedFrameSize() + config.PtrSize && isSameSym(sym, "runtime.newobject")
// result: (Plain nil succ)
for {
v := b.Control
if v.Op != OpNilCheck {
break
}
v_0 := v.Args[0]
if v_0.Op != OpOffPtr {
break
}
v_0_0 := v_0.Args[0]
if v_0_0.Op != OpLoad {
break
}
v_0_0_0 := v_0_0.Args[0]
if v_0_0_0.Op != OpOffPtr {
break
}
c := v_0_0_0.AuxInt
v_0_0_0_0 := v_0_0_0.Args[0]
if v_0_0_0_0.Op != OpSP {
break
}
mem := v_0_0.Args[1]
if mem.Op != OpStaticCall {
break
}
sym := mem.Aux
succ := b.Succs[0]
if !(c == config.ctxt.FixedFrameSize()+config.PtrSize && isSameSym(sym, "runtime.newobject")) {
break
}
b.Kind = BlockPlain
b.SetControl(nil)
_ = succ
return true
}
case BlockIf:
// match: (If (Not cond) yes no)
// cond:
......
src/cmd/compile/internal/ssa/schedule.go
View file @ 3134ab3c
......@@ -8,6 +8,7 @@ import "container/heap"
const (
ScorePhi = iota // towards top of block
ScoreNilCheck
ScoreReadTuple
ScoreVarDef
ScoreMemory
......@@ -96,6 +97,9 @@ func schedule(f *Func) {
f.Fatalf("LoweredGetClosurePtr appeared outside of entry block, b=%s", b.String())
}
score[v.ID] = ScorePhi
case v.Op == OpAMD64LoweredNilCheck || v.Op == OpPPC64LoweredNilCheck || v.Op == OpARMLoweredNilCheck || v.Op == OpARM64LoweredNilCheck || v.Op == Op386LoweredNilCheck || v.Op == OpMIPS64LoweredNilCheck:
// Nil checks must come before loads from the same address.
score[v.ID] = ScoreNilCheck
case v.Op == OpPhi:
// We want all the phis first.
score[v.ID] = ScorePhi
......
src/cmd/compile/internal/x86/ssa.go
View file @ 3134ab3c
......@@ -820,54 +820,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
case ssa.OpKeepAlive:
gc.KeepAlive(v)
case ssa.Op386LoweredNilCheck:
// Optimization - if the subsequent block has a load or store
// at the same address, we don't need to issue this instruction.
mem := v.Args[1]
for _, w := range v.Block.Succs[0].Block().Values {
if w.Op == ssa.OpPhi {
if w.Type.IsMemory() {
mem = w
}
continue
}
if len(w.Args) == 0 || !w.Args[len(w.Args)-1].Type.IsMemory() {
// w doesn't use a store - can't be a memory op.
continue
}
if w.Args[len(w.Args)-1] != mem {
v.Fatalf("wrong store after nilcheck v=%s w=%s", v, w)
}
switch w.Op {
case ssa.Op386MOVLload, ssa.Op386MOVWload, ssa.Op386MOVBload,
ssa.Op386MOVLstore, ssa.Op386MOVWstore, ssa.Op386MOVBstore,
ssa.Op386MOVBLSXload, ssa.Op386MOVWLSXload,
ssa.Op386MOVSSload, ssa.Op386MOVSDload,
ssa.Op386MOVSSstore, ssa.Op386MOVSDstore:
if w.Args[0] == v.Args[0] && w.Aux == nil && w.AuxInt >= 0 && w.AuxInt < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
case ssa.Op386MOVLstoreconst, ssa.Op386MOVWstoreconst, ssa.Op386MOVBstoreconst:
off := ssa.ValAndOff(v.AuxInt).Off()
if w.Args[0] == v.Args[0] && w.Aux == nil && off >= 0 && off < minZeroPage {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
gc.Warnl(v.Line, "removed nil check")
}
return
}
}
if w.Type.IsMemory() {
if w.Op == ssa.OpVarDef || w.Op == ssa.OpVarKill || w.Op == ssa.OpVarLive {
// these ops are OK
mem = w
continue
}
// We can't delay the nil check past the next store.
break
}
}
// Issue a load which will fault if the input is nil.
// TODO: We currently use the 2-byte instruction TESTB AX, (reg).
// Should we use the 3-byte TESTB $0, (reg) instead? It is larger
......@@ -925,7 +877,7 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
}
switch b.Kind {
case ssa.BlockPlain, ssa.BlockCheck:
case ssa.BlockPlain:
if b.Succs[0].Block() != next {
p := gc.Prog(obj.AJMP)
p.To.Type = obj.TYPE_BRANCH
......
test/nilptr3_ssa.go
View file @ 3134ab3c
......@@ -154,7 +154,7 @@ func f4(x *[10]int) {
// and the offset is small enough that if x is nil, the address will still be
// in the first unmapped page of memory.
_ = x[9] // ERROR "removed nil check"
_ = x[9] // ERROR "generated nil check" // bug: would like to remove this check (but nilcheck and load are in different blocks)
for {
if x[9] != 0 { // ERROR "removed nil check"
......
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