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cmd/compile: Fix constant-folding of unsigned shifts

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Make sure the results of unsigned constant-folded
shifts are sign-extended into the AuxInt field.

Fixes #15175

Change-Id: I3490d1bc3d9b2e1578ed30964645508577894f58
Reviewed-on: https://go-review.googlesource.com/21586
Reviewed-by: Alexandru Moșoi <alexandru@mosoi.ro>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Keith Randall 2016-04-07 10:21:35 -07:00
parent dfded57819
commit 68ac1f7746
3 changed files with 75 additions and 9 deletions
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12
src/cmd/compile/internal/ssa/rewritegeneric.go
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@ -6185,7 +6185,7 @@ func rewriteValuegeneric_OpRsh16Ux64(v *Value, config *Config) bool {
_ = b
// match: (Rsh16Ux64 (Const16 [c]) (Const64 [d]))
// cond:
// result: (Const16 [int64(uint16(c) >> uint64(d))])
// result: (Const16 [int64(int16(uint16(c) >> uint64(d)))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst16 {
@ -6198,7 +6198,7 @@ func rewriteValuegeneric_OpRsh16Ux64(v *Value, config *Config) bool {
}
d := v_1.AuxInt
v.reset(OpConst16)
v.AuxInt = int64(uint16(c) >> uint64(d))
v.AuxInt = int64(int16(uint16(c) >> uint64(d)))
return true
}
// match: (Rsh16Ux64 (Const16 [0]) _)
@ -6547,7 +6547,7 @@ func rewriteValuegeneric_OpRsh32Ux64(v *Value, config *Config) bool {
_ = b
// match: (Rsh32Ux64 (Const32 [c]) (Const64 [d]))
// cond:
// result: (Const32 [int64(uint32(c) >> uint64(d))])
// result: (Const32 [int64(int32(uint32(c) >> uint64(d)))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst32 {
@ -6560,7 +6560,7 @@ func rewriteValuegeneric_OpRsh32Ux64(v *Value, config *Config) bool {
}
d := v_1.AuxInt
v.reset(OpConst32)
v.AuxInt = int64(uint32(c) >> uint64(d))
v.AuxInt = int64(int32(uint32(c) >> uint64(d)))
return true
}
// match: (Rsh32Ux64 (Const32 [0]) _)
@ -7353,7 +7353,7 @@ func rewriteValuegeneric_OpRsh8Ux64(v *Value, config *Config) bool {
_ = b
// match: (Rsh8Ux64 (Const8 [c]) (Const64 [d]))
// cond:
// result: (Const8 [int64(uint8(c) >> uint64(d))])
// result: (Const8 [int64(int8(uint8(c) >> uint64(d)))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst8 {
@ -7366,7 +7366,7 @@ func rewriteValuegeneric_OpRsh8Ux64(v *Value, config *Config) bool {
}
d := v_1.AuxInt
v.reset(OpConst8)
v.AuxInt = int64(uint8(c) >> uint64(d))
v.AuxInt = int64(int8(uint8(c) >> uint64(d)))
return true
}
// match: (Rsh8Ux64 (Const8 [0]) _)