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cmd/compile: fix constant folding of right shifts on s390x

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Repeat previous fix on amd64 for s390x.
Sub-word right shifts should sign extend before shifting.

Update #23812

Change-Id: I2d770190c7d8a22310b0dbd9facb3fb05afa362a
Reviewed-on: https://go-review.googlesource.com/94028
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Keith Randall 2018-02-14 14:21:31 -08:00 committed by Keith Randall
parent c3e8da67dd
commit 1566bf9025
3 changed files with 7 additions and 7 deletions
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2
src/cmd/compile/internal/ssa/gen/S390X.rules
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@ -1091,7 +1091,7 @@
(SUBconst (MOVDconst [d]) [c]) -> (MOVDconst [d-c])
(SUBconst (SUBconst x [d]) [c]) && is32Bit(-c-d) -> (ADDconst [-c-d] x)
(SRADconst [c] (MOVDconst [d])) -> (MOVDconst [d>>uint64(c)])
(SRAWconst [c] (MOVDconst [d])) -> (MOVDconst [d>>uint64(c)])
(SRAWconst [c] (MOVDconst [d])) -> (MOVDconst [int64(int32(d))>>uint64(c)])
(NEG (MOVDconst [c])) -> (MOVDconst [-c])
(NEGW (MOVDconst [c])) -> (MOVDconst [int64(int32(-c))])
(MULLDconst [c] (MOVDconst [d])) -> (MOVDconst [c*d])

8
src/cmd/compile/internal/ssa/gen/S390XOps.go
View File

@ -310,15 +310,15 @@ func init() {
{name: "SLWconst", argLength: 1, reg: gp11, asm: "SLW", aux: "Int8"}, // arg0 << auxint, shift amount 0-31
{name: "SRD", argLength: 2, reg: sh21, asm: "SRD"}, // unsigned arg0 >> arg1, shift amount is mod 64
{name: "SRW", argLength: 2, reg: sh21, asm: "SRW"}, // unsigned arg0 >> arg1, shift amount is mod 32
{name: "SRW", argLength: 2, reg: sh21, asm: "SRW"}, // unsigned uint32(arg0) >> arg1, shift amount is mod 32
{name: "SRDconst", argLength: 1, reg: gp11, asm: "SRD", aux: "Int8"}, // unsigned arg0 >> auxint, shift amount 0-63
{name: "SRWconst", argLength: 1, reg: gp11, asm: "SRW", aux: "Int8"}, // unsigned arg0 >> auxint, shift amount 0-31
{name: "SRWconst", argLength: 1, reg: gp11, asm: "SRW", aux: "Int8"}, // unsigned uint32(arg0) >> auxint, shift amount 0-31
// Arithmetic shifts clobber flags.
{name: "SRAD", argLength: 2, reg: sh21, asm: "SRAD", clobberFlags: true}, // signed arg0 >> arg1, shift amount is mod 64
{name: "SRAW", argLength: 2, reg: sh21, asm: "SRAW", clobberFlags: true}, // signed arg0 >> arg1, shift amount is mod 32
{name: "SRAW", argLength: 2, reg: sh21, asm: "SRAW", clobberFlags: true}, // signed int32(arg0) >> arg1, shift amount is mod 32
{name: "SRADconst", argLength: 1, reg: gp11, asm: "SRAD", aux: "Int8", clobberFlags: true}, // signed arg0 >> auxint, shift amount 0-63
{name: "SRAWconst", argLength: 1, reg: gp11, asm: "SRAW", aux: "Int8", clobberFlags: true}, // signed arg0 >> auxint, shift amount 0-31
{name: "SRAWconst", argLength: 1, reg: gp11, asm: "SRAW", aux: "Int8", clobberFlags: true}, // signed int32(arg0) >> auxint, shift amount 0-31
{name: "RLLGconst", argLength: 1, reg: gp11, asm: "RLLG", aux: "Int8"}, // arg0 rotate left auxint, rotate amount 0-63
{name: "RLLconst", argLength: 1, reg: gp11, asm: "RLL", aux: "Int8"}, // arg0 rotate left auxint, rotate amount 0-31

4
src/cmd/compile/internal/ssa/rewriteS390X.go
View File

@ -37199,7 +37199,7 @@ func rewriteValueS390X_OpS390XSRAW_0(v *Value) bool {
func rewriteValueS390X_OpS390XSRAWconst_0(v *Value) bool {
// match: (SRAWconst [c] (MOVDconst [d]))
// cond:
// result: (MOVDconst [d>>uint64(c)])
// result: (MOVDconst [int64(int32(d))>>uint64(c)])
for {
c := v.AuxInt
v_0 := v.Args[0]
@ -37208,7 +37208,7 @@ func rewriteValueS390X_OpS390XSRAWconst_0(v *Value) bool {
}
d := v_0.AuxInt
v.reset(OpS390XMOVDconst)
v.AuxInt = d >> uint64(c)
v.AuxInt = int64(int32(d)) >> uint64(c)
return true
}
return false