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cmd/compile: fix subword store/load elision for amd64, x86, arm

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Replacing byteload-of-bytestore-of-x with x is incorrect
when x contains a larger-than-byte value (and so on for
16 and 32-bit load/store pairs).  Replace "x" with the
appropriate zero/sign extension of x, which if unnecessary
will be repaired by other rules.

Made logic for arm match x86 and amd64; yields minor extra
optimization, plus I am (much) more confident it's correct,
despite inability to reproduce bug on arm.

Ppc64 lacks this optimization, hence lacks this problem.

See related https://golang.org/cl/37154/
Fixes #20530.

Change-Id: I6af9cac2ad43bee99cafdcb04725ce7e55a43323
Reviewed-on: https://go-review.googlesource.com/44355
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
David Chase 2017-05-30 16:06:59 -04:00
parent d10549fb57
commit 9613a638a9
7 changed files with 182 additions and 47 deletions
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8
src/cmd/compile/internal/ssa/gen/386.rules
View File

@ -615,10 +615,12 @@
(MOVWLZX x:(MOVWloadidx1 [off] {sym} ptr idx mem)) && x.Uses == 1 && clobber(x) -> @x.Block (MOVWloadidx1 <v.Type> [off] {sym} ptr idx mem)
(MOVWLZX x:(MOVWloadidx2 [off] {sym} ptr idx mem)) && x.Uses == 1 && clobber(x) -> @x.Block (MOVWloadidx2 <v.Type> [off] {sym} ptr idx mem)
// replace load from same location as preceding store with copy
(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
(MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
// replace load from same location as preceding store with zero/sign extension (or copy in case of full width)
(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBLZX x)
(MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVWLZX x)
(MOVLload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
(MOVBLSXload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBLSX x)
(MOVWLSXload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVWLSX x)
// Fold extensions and ANDs together.
(MOVBLZX (ANDLconst [c] x)) -> (ANDLconst [c & 0xff] x)

11
src/cmd/compile/internal/ssa/gen/AMD64.rules
View File

@ -965,11 +965,14 @@
(MOVLQZX x:(MOVLloadidx1 [off] {sym} ptr idx mem)) && x.Uses == 1 && clobber(x) -> @x.Block (MOVLloadidx1 <v.Type> [off] {sym} ptr idx mem)
(MOVLQZX x:(MOVLloadidx4 [off] {sym} ptr idx mem)) && x.Uses == 1 && clobber(x) -> @x.Block (MOVLloadidx4 <v.Type> [off] {sym} ptr idx mem)
// replace load from same location as preceding store with copy
(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
(MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
(MOVLload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
// replace load from same location as preceding store with zero/sign extension (or copy in case of full width)
(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBQZX x)
(MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVWQZX x)
(MOVLload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVLQZX x)
(MOVQload [off] {sym} ptr (MOVQstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
(MOVBQSXload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBQSX x)
(MOVWQSXload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVWQSX x)
(MOVLQSXload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVLQSX x)
// Fold extensions and ANDs together.
(MOVBQZX (ANDLconst [c] x)) -> (ANDLconst [c & 0xff] x)

11
src/cmd/compile/internal/ssa/gen/ARM.rules
View File

@ -485,12 +485,13 @@
(MOVDstore [off1] {sym1} (MOVWaddr [off2] {sym2} ptr) val mem) && canMergeSym(sym1,sym2) ->
(MOVDstore [off1+off2] {mergeSym(sym1,sym2)} ptr val mem)
// replace load from same location as preceding store with copy
(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type) -> x
(MOVBUload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type) -> x
(MOVHload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type) -> x
(MOVHUload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type) -> x
// replace load from same location as preceding store with zero/sign extension (or copy in case of full width)
(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBreg x)
(MOVBUload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBUreg x)
(MOVHload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVHreg x)
(MOVHUload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVHUreg x)
(MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
(MOVFload [off] {sym} ptr (MOVFstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
(MOVDload [off] {sym} ptr (MOVDstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x

58
src/cmd/compile/internal/ssa/rewrite386.go
View File

@ -2886,6 +2886,30 @@ func rewriteValue386_Op386MOVBLSXload_0(v *Value) bool {
_ = b
config := b.Func.Config
_ = config
// match: (MOVBLSXload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: (MOVBLSX x)
for {
off := v.AuxInt
sym := v.Aux
_ = v.Args[1]
ptr := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != Op386MOVBstore {
break
}
off2 := v_1.AuxInt
sym2 := v_1.Aux
_ = v_1.Args[2]
ptr2 := v_1.Args[0]
x := v_1.Args[1]
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(Op386MOVBLSX)
v.AddArg(x)
return true
}
// match: (MOVBLSXload [off1] {sym1} (LEAL [off2] {sym2} base) mem)
// cond: is32Bit(off1+off2) && canMergeSym(sym1, sym2) && (base.Op != OpSB || !config.ctxt.Flag_shared)
// result: (MOVBLSXload [off1+off2] {mergeSym(sym1,sym2)} base mem)
@ -2994,7 +3018,7 @@ func rewriteValue386_Op386MOVBload_0(v *Value) bool {
_ = config
// match: (MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: x
// result: (MOVBLZX x)
for {
off := v.AuxInt
sym := v.Aux
@ -3012,8 +3036,7 @@ func rewriteValue386_Op386MOVBload_0(v *Value) bool {
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpCopy)
v.Type = x.Type
v.reset(Op386MOVBLZX)
v.AddArg(x)
return true
}
@ -6324,6 +6347,30 @@ func rewriteValue386_Op386MOVWLSXload_0(v *Value) bool {
_ = b
config := b.Func.Config
_ = config
// match: (MOVWLSXload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: (MOVWLSX x)
for {
off := v.AuxInt
sym := v.Aux
_ = v.Args[1]
ptr := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != Op386MOVWstore {
break
}
off2 := v_1.AuxInt
sym2 := v_1.Aux
_ = v_1.Args[2]
ptr2 := v_1.Args[0]
x := v_1.Args[1]
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(Op386MOVWLSX)
v.AddArg(x)
return true
}
// match: (MOVWLSXload [off1] {sym1} (LEAL [off2] {sym2} base) mem)
// cond: is32Bit(off1+off2) && canMergeSym(sym1, sym2) && (base.Op != OpSB || !config.ctxt.Flag_shared)
// result: (MOVWLSXload [off1+off2] {mergeSym(sym1,sym2)} base mem)
@ -6460,7 +6507,7 @@ func rewriteValue386_Op386MOVWload_0(v *Value) bool {
_ = config
// match: (MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: x
// result: (MOVWLZX x)
for {
off := v.AuxInt
sym := v.Aux
@ -6478,8 +6525,7 @@ func rewriteValue386_Op386MOVWload_0(v *Value) bool {
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpCopy)
v.Type = x.Type
v.reset(Op386MOVWLZX)
v.AddArg(x)
return true
}

87
src/cmd/compile/internal/ssa/rewriteAMD64.go
View File

@ -4335,6 +4335,30 @@ func rewriteValueAMD64_OpAMD64MOVBQSX_0(v *Value) bool {
return false
}
func rewriteValueAMD64_OpAMD64MOVBQSXload_0(v *Value) bool {
// match: (MOVBQSXload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: (MOVBQSX x)
for {
off := v.AuxInt
sym := v.Aux
_ = v.Args[1]
ptr := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != OpAMD64MOVBstore {
break
}
off2 := v_1.AuxInt
sym2 := v_1.Aux
_ = v_1.Args[2]
ptr2 := v_1.Args[0]
x := v_1.Args[1]
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpAMD64MOVBQSX)
v.AddArg(x)
return true
}
// match: (MOVBQSXload [off1] {sym1} (LEAQ [off2] {sym2} base) mem)
// cond: is32Bit(off1+off2) && canMergeSym(sym1, sym2)
// result: (MOVBQSXload [off1+off2] {mergeSym(sym1,sym2)} base mem)
@ -4530,7 +4554,7 @@ func rewriteValueAMD64_OpAMD64MOVBQZX_0(v *Value) bool {
func rewriteValueAMD64_OpAMD64MOVBload_0(v *Value) bool {
// match: (MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: x
// result: (MOVBQZX x)
for {
off := v.AuxInt
sym := v.Aux
@ -4548,8 +4572,7 @@ func rewriteValueAMD64_OpAMD64MOVBload_0(v *Value) bool {
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpCopy)
v.Type = x.Type
v.reset(OpAMD64MOVBQZX)
v.AddArg(x)
return true
}
@ -6387,6 +6410,30 @@ func rewriteValueAMD64_OpAMD64MOVLQSX_0(v *Value) bool {
return false
}
func rewriteValueAMD64_OpAMD64MOVLQSXload_0(v *Value) bool {
// match: (MOVLQSXload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: (MOVLQSX x)
for {
off := v.AuxInt
sym := v.Aux
_ = v.Args[1]
ptr := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != OpAMD64MOVLstore {
break
}
off2 := v_1.AuxInt
sym2 := v_1.Aux
_ = v_1.Args[2]
ptr2 := v_1.Args[0]
x := v_1.Args[1]
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpAMD64MOVLQSX)
v.AddArg(x)
return true
}
// match: (MOVLQSXload [off1] {sym1} (LEAQ [off2] {sym2} base) mem)
// cond: is32Bit(off1+off2) && canMergeSym(sym1, sym2)
// result: (MOVLQSXload [off1+off2] {mergeSym(sym1,sym2)} base mem)
@ -6636,7 +6683,7 @@ func rewriteValueAMD64_OpAMD64MOVLatomicload_0(v *Value) bool {
func rewriteValueAMD64_OpAMD64MOVLload_0(v *Value) bool {
// match: (MOVLload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: x
// result: (MOVLQZX x)
for {
off := v.AuxInt
sym := v.Aux
@ -6654,8 +6701,7 @@ func rewriteValueAMD64_OpAMD64MOVLload_0(v *Value) bool {
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpCopy)
v.Type = x.Type
v.reset(OpAMD64MOVLQZX)
v.AddArg(x)
return true
}
@ -10594,6 +10640,30 @@ func rewriteValueAMD64_OpAMD64MOVWQSX_0(v *Value) bool {
return false
}
func rewriteValueAMD64_OpAMD64MOVWQSXload_0(v *Value) bool {
// match: (MOVWQSXload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: (MOVWQSX x)
for {
off := v.AuxInt
sym := v.Aux
_ = v.Args[1]
ptr := v.Args[0]
v_1 := v.Args[1]
if v_1.Op != OpAMD64MOVWstore {
break
}
off2 := v_1.AuxInt
sym2 := v_1.Aux
_ = v_1.Args[2]
ptr2 := v_1.Args[0]
x := v_1.Args[1]
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpAMD64MOVWQSX)
v.AddArg(x)
return true
}
// match: (MOVWQSXload [off1] {sym1} (LEAQ [off2] {sym2} base) mem)
// cond: is32Bit(off1+off2) && canMergeSym(sym1, sym2)
// result: (MOVWQSXload [off1+off2] {mergeSym(sym1,sym2)} base mem)
@ -10804,7 +10874,7 @@ func rewriteValueAMD64_OpAMD64MOVWQZX_0(v *Value) bool {
func rewriteValueAMD64_OpAMD64MOVWload_0(v *Value) bool {
// match: (MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: x
// result: (MOVWQZX x)
for {
off := v.AuxInt
sym := v.Aux
@ -10822,8 +10892,7 @@ func rewriteValueAMD64_OpAMD64MOVWload_0(v *Value) bool {
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpCopy)
v.Type = x.Type
v.reset(OpAMD64MOVWQZX)
v.AddArg(x)
return true
}

36
src/cmd/compile/internal/ssa/rewriteARM.go
View File

@ -5823,8 +5823,8 @@ func rewriteValueARM_OpARMMOVBUload_0(v *Value) bool {
return true
}
// match: (MOVBUload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)
// result: x
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: (MOVBUreg x)
for {
off := v.AuxInt
sym := v.Aux
@ -5839,11 +5839,10 @@ func rewriteValueARM_OpARMMOVBUload_0(v *Value) bool {
_ = v_1.Args[2]
ptr2 := v_1.Args[0]
x := v_1.Args[1]
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)) {
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpCopy)
v.Type = x.Type
v.reset(OpARMMOVBUreg)
v.AddArg(x)
return true
}
@ -5974,8 +5973,8 @@ func rewriteValueARM_OpARMMOVBload_0(v *Value) bool {
return true
}
// match: (MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)
// result: x
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: (MOVBreg x)
for {
off := v.AuxInt
sym := v.Aux
@ -5990,11 +5989,10 @@ func rewriteValueARM_OpARMMOVBload_0(v *Value) bool {
_ = v_1.Args[2]
ptr2 := v_1.Args[0]
x := v_1.Args[1]
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)) {
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpCopy)
v.Type = x.Type
v.reset(OpARMMOVBreg)
v.AddArg(x)
return true
}
@ -6634,8 +6632,8 @@ func rewriteValueARM_OpARMMOVHUload_0(v *Value) bool {
return true
}
// match: (MOVHUload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)
// result: x
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: (MOVHUreg x)
for {
off := v.AuxInt
sym := v.Aux
@ -6650,11 +6648,10 @@ func rewriteValueARM_OpARMMOVHUload_0(v *Value) bool {
_ = v_1.Args[2]
ptr2 := v_1.Args[0]
x := v_1.Args[1]
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)) {
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpCopy)
v.Type = x.Type
v.reset(OpARMMOVHUreg)
v.AddArg(x)
return true
}
@ -6810,8 +6807,8 @@ func rewriteValueARM_OpARMMOVHload_0(v *Value) bool {
return true
}
// match: (MOVHload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _))
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)
// result: x
// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
// result: (MOVHreg x)
for {
off := v.AuxInt
sym := v.Aux
@ -6826,11 +6823,10 @@ func rewriteValueARM_OpARMMOVHload_0(v *Value) bool {
_ = v_1.Args[2]
ptr2 := v_1.Args[0]
x := v_1.Args[1]
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)) {
if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
break
}
v.reset(OpCopy)
v.Type = x.Type
v.reset(OpARMMOVHreg)
v.AddArg(x)
return true
}

18
test/fixedbugs/issue20530.go Normal file
View File

@ -0,0 +1,18 @@
// run
// Copyright 2017 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 main
var a uint8
func main() {
b := int8(func() int32 { return -1 }())
a = uint8(b)
if int32(a) != 255 {
// Failing case prints 'got 255 expected 255'
println("got", a, "expected 255")
}
}