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cmd/compile: re-enable nilcheck removal for newobject

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Also add compiler debug ouput and add a test.

Fixes #15390.

Change-Id: Iceba1414c29bcc213b87837387bf8ded1f3157f1
Reviewed-on: https://go-review.googlesource.com/30011
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Cherry Zhang 2016-09-28 10:20:24 -04:00
parent 456a01ac47
commit 4d07d3e29c
5 changed files with 95 additions and 10 deletions
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9
src/cmd/compile/internal/ssa/config.go
View File

@ -17,6 +17,7 @@ type Config struct {
arch string // "amd64", etc.
IntSize int64 // 4 or 8
PtrSize int64 // 4 or 8
RegSize int64 // 4 or 8
lowerBlock func(*Block, *Config) bool // lowering function
lowerValue func(*Value, *Config) bool // lowering function
registers []Register // machine registers
@ -132,6 +133,7 @@ func NewConfig(arch string, fe Frontend, ctxt *obj.Link, optimize bool) *Config
case "amd64":
c.IntSize = 8
c.PtrSize = 8
c.RegSize = 8
c.lowerBlock = rewriteBlockAMD64
c.lowerValue = rewriteValueAMD64
c.registers = registersAMD64[:]
@ -142,6 +144,7 @@ func NewConfig(arch string, fe Frontend, ctxt *obj.Link, optimize bool) *Config
case "amd64p32":
c.IntSize = 4
c.PtrSize = 4
c.RegSize = 8
c.lowerBlock = rewriteBlockAMD64
c.lowerValue = rewriteValueAMD64
c.registers = registersAMD64[:]
@ -153,6 +156,7 @@ func NewConfig(arch string, fe Frontend, ctxt *obj.Link, optimize bool) *Config
case "386":
c.IntSize = 4
c.PtrSize = 4
c.RegSize = 4
c.lowerBlock = rewriteBlock386
c.lowerValue = rewriteValue386
c.registers = registers386[:]
@ -163,6 +167,7 @@ func NewConfig(arch string, fe Frontend, ctxt *obj.Link, optimize bool) *Config
case "arm":
c.IntSize = 4
c.PtrSize = 4
c.RegSize = 4
c.lowerBlock = rewriteBlockARM
c.lowerValue = rewriteValueARM
c.registers = registersARM[:]
@ -173,6 +178,7 @@ func NewConfig(arch string, fe Frontend, ctxt *obj.Link, optimize bool) *Config
case "arm64":
c.IntSize = 8
c.PtrSize = 8
c.RegSize = 8
c.lowerBlock = rewriteBlockARM64
c.lowerValue = rewriteValueARM64
c.registers = registersARM64[:]
@ -187,6 +193,7 @@ func NewConfig(arch string, fe Frontend, ctxt *obj.Link, optimize bool) *Config
case "ppc64le":
c.IntSize = 8
c.PtrSize = 8
c.RegSize = 8
c.lowerBlock = rewriteBlockPPC64
c.lowerValue = rewriteValuePPC64
c.registers = registersPPC64[:]
@ -199,6 +206,7 @@ func NewConfig(arch string, fe Frontend, ctxt *obj.Link, optimize bool) *Config
case "mips64", "mips64le":
c.IntSize = 8
c.PtrSize = 8
c.RegSize = 8
c.lowerBlock = rewriteBlockMIPS64
c.lowerValue = rewriteValueMIPS64
c.registers = registersMIPS64[:]
@ -210,6 +218,7 @@ func NewConfig(arch string, fe Frontend, ctxt *obj.Link, optimize bool) *Config
case "s390x":
c.IntSize = 8
c.PtrSize = 8
c.RegSize = 8
c.lowerBlock = rewriteBlockS390X
c.lowerValue = rewriteValueS390X
c.registers = registersS390X[:]

22
src/cmd/compile/internal/ssa/gen/generic.rules
View File

@ -958,13 +958,15 @@
-> mem
// 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)
(NilCheck (Load (OffPtr [c] (SP)) mem) mem)
&& mem.Op == OpStaticCall
&& isSameSym(mem.Aux, "runtime.newobject")
&& c == config.ctxt.FixedFrameSize() + config.RegSize // offset of return value
&& warnRule(config.Debug_checknil() && int(v.Line) > 1, v, "removed nil check")
-> (Invalid)
(NilCheck (OffPtr (Load (OffPtr [c] (SP)) mem)) mem)
&& mem.Op == OpStaticCall
&& isSameSym(mem.Aux, "runtime.newobject")
&& c == config.ctxt.FixedFrameSize() + config.RegSize // offset of return value
&& warnRule(config.Debug_checknil() && int(v.Line) > 1, v, "removed nil check")
-> (Invalid)

9
src/cmd/compile/internal/ssa/rewrite.go
View File

@ -370,6 +370,15 @@ func noteRule(s string) bool {
return true
}
// warnRule generates a compiler debug output with string s when
// cond is true and the rule is fired.
func warnRule(cond bool, v *Value, s string) bool {
if cond {
v.Block.Func.Config.Warnl(v.Line, "removed nil check")
}
return true
}
// logRule logs the use of the rule s. This will only be enabled if
// rewrite rules were generated with the -log option, see gen/rulegen.go.
func logRule(s string) {

58
src/cmd/compile/internal/ssa/rewritegeneric.go
View File

@ -6380,6 +6380,64 @@ func rewriteValuegeneric_OpNilCheck(v *Value, config *Config) bool {
v.AddArg(mem)
return true
}
// match: (NilCheck (Load (OffPtr [c] (SP)) mem) mem)
// cond: mem.Op == OpStaticCall && isSameSym(mem.Aux, "runtime.newobject") && c == config.ctxt.FixedFrameSize() + config.RegSize && warnRule(config.Debug_checknil() && int(v.Line) > 1, v, "removed nil check")
// result: (Invalid)
for {
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 != v.Args[1] {
break
}
if !(mem.Op == OpStaticCall && isSameSym(mem.Aux, "runtime.newobject") && c == config.ctxt.FixedFrameSize()+config.RegSize && warnRule(config.Debug_checknil() && int(v.Line) > 1, v, "removed nil check")) {
break
}
v.reset(OpInvalid)
return true
}
// match: (NilCheck (OffPtr (Load (OffPtr [c] (SP)) mem)) mem)
// cond: mem.Op == OpStaticCall && isSameSym(mem.Aux, "runtime.newobject") && c == config.ctxt.FixedFrameSize() + config.RegSize && warnRule(config.Debug_checknil() && int(v.Line) > 1, v, "removed nil check")
// result: (Invalid)
for {
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 != v.Args[1] {
break
}
if !(mem.Op == OpStaticCall && isSameSym(mem.Aux, "runtime.newobject") && c == config.ctxt.FixedFrameSize()+config.RegSize && warnRule(config.Debug_checknil() && int(v.Line) > 1, v, "removed nil check")) {
break
}
v.reset(OpInvalid)
return true
}
return false
}
func rewriteValuegeneric_OpNot(v *Value, config *Config) bool {

7
test/nilptr3.go
View File

@ -247,3 +247,10 @@ func f(t *TT) *byte {
s := &t.SS // ERROR "removed nil check"
return &s.x // ERROR "generated nil check"
}
// make sure not to do nil check for newobject
func f7() (*Struct, float64) {
t := new(Struct)
p := &t.Y // ERROR "removed nil check"
return t, *p // ERROR "removed nil check"
}