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cmd/compile: remove more extension ops when not needed

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If we're not using the upper bits, don't bother issuing a
sign/zero extension operation.

For arm64, after CL 520916 which fixed a correctness bug with
extensions but as a side effect leaves many unnecessary ones
still in place.

Change-Id: I5f4fe4efbf2e9f80969ab5b9a6122fb812dc2ec0
Reviewed-on: https://go-review.googlesource.com/c/go/+/521496
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
Keith Randall 2023-08-21 10:03:07 -07:00
parent a9bedc36a5
commit 0b47b94a62
3 changed files with 76 additions and 0 deletions
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5
src/cmd/compile/internal/ssa/_gen/ARM64.rules
View File

@ -1574,6 +1574,11 @@
// zero upper bit of the register; no need to zero-extend
(MOVBUreg x:((Equal|NotEqual|LessThan|LessThanU|LessThanF|LessEqual|LessEqualU|LessEqualF|GreaterThan|GreaterThanU|GreaterThanF|GreaterEqual|GreaterEqualU|GreaterEqualF) _)) => (MOVDreg x)
// Don't bother extending if we're not using the higher bits.
(MOV(B|BU)reg x) && v.Type.Size() <= 1 => x
(MOV(H|HU)reg x) && v.Type.Size() <= 2 => x
(MOV(W|WU)reg x) && v.Type.Size() <= 4 => x
// omit unsign extension
(MOVWUreg x) && zeroUpper32Bits(x, 3) => x

66
src/cmd/compile/internal/ssa/rewriteARM64.go
View File

@ -8472,6 +8472,17 @@ func rewriteValueARM64_OpARM64MOVBUreg(v *Value) bool {
v.AddArg(x)
return true
}
// match: (MOVBUreg x)
// cond: v.Type.Size() <= 1
// result: x
for {
x := v_0
if !(v.Type.Size() <= 1) {
break
}
v.copyOf(x)
return true
}
// match: (MOVBUreg (SLLconst [lc] x))
// cond: lc >= 8
// result: (MOVDconst [0])
@ -8735,6 +8746,17 @@ func rewriteValueARM64_OpARM64MOVBreg(v *Value) bool {
v.AuxInt = int64ToAuxInt(int64(int8(c)))
return true
}
// match: (MOVBreg x)
// cond: v.Type.Size() <= 1
// result: x
for {
x := v_0
if !(v.Type.Size() <= 1) {
break
}
v.copyOf(x)
return true
}
// match: (MOVBreg <t> (ANDconst x [c]))
// cond: uint64(c) & uint64(0xffffffffffffff80) == 0
// result: (ANDconst <t> x [c])
@ -10386,6 +10408,17 @@ func rewriteValueARM64_OpARM64MOVHUreg(v *Value) bool {
v.AuxInt = int64ToAuxInt(int64(uint16(c)))
return true
}
// match: (MOVHUreg x)
// cond: v.Type.Size() <= 2
// result: x
for {
x := v_0
if !(v.Type.Size() <= 2) {
break
}
v.copyOf(x)
return true
}
// match: (MOVHUreg (SLLconst [lc] x))
// cond: lc >= 16
// result: (MOVDconst [0])
@ -10832,6 +10865,17 @@ func rewriteValueARM64_OpARM64MOVHreg(v *Value) bool {
v.AuxInt = int64ToAuxInt(int64(int16(c)))
return true
}
// match: (MOVHreg x)
// cond: v.Type.Size() <= 2
// result: x
for {
x := v_0
if !(v.Type.Size() <= 2) {
break
}
v.copyOf(x)
return true
}
// match: (MOVHreg <t> (ANDconst x [c]))
// cond: uint64(c) & uint64(0xffffffffffff8000) == 0
// result: (ANDconst <t> x [c])
@ -12011,6 +12055,17 @@ func rewriteValueARM64_OpARM64MOVWUreg(v *Value) bool {
return true
}
// match: (MOVWUreg x)
// cond: v.Type.Size() <= 4
// result: x
for {
x := v_0
if !(v.Type.Size() <= 4) {
break
}
v.copyOf(x)
return true
}
// match: (MOVWUreg x)
// cond: zeroUpper32Bits(x, 3)
// result: x
for {
@ -12525,6 +12580,17 @@ func rewriteValueARM64_OpARM64MOVWreg(v *Value) bool {
v.AuxInt = int64ToAuxInt(int64(int32(c)))
return true
}
// match: (MOVWreg x)
// cond: v.Type.Size() <= 4
// result: x
for {
x := v_0
if !(v.Type.Size() <= 4) {
break
}
v.copyOf(x)
return true
}
// match: (MOVWreg <t> (ANDconst x [c]))
// cond: uint64(c) & uint64(0xffffffff80000000) == 0
// result: (ANDconst <t> x [c])

5
test/codegen/noextend.go
View File

@ -279,3 +279,8 @@ func shouldSignEXT(x int) int64 {
return ret
}
func noIntermediateExtension(a, b, c uint32) uint32 {
// arm64:-"MOVWU"
return a*b*9 + c
}