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cmd/compile: merge ANDconst and UBFX into UBFX on arm64

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Add a new rewrite rule to merge ANDconst and UBFX into
UBFX.

Add test cases.

Change-Id: I24d6442d0c956d7ce092c3a3858d4a3a41771670
Reviewed-on: https://go-review.googlesource.com/c/go/+/377054
Trust: Fannie Zhang <Fannie.Zhang@arm.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
fanzha02 2020-11-03 17:31:04 +08:00 committed by Fannie Zhang
parent a10a209b23
commit 8ab42a945a
3 changed files with 47 additions and 1 deletions
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6
src/cmd/compile/internal/ssa/gen/ARM64.rules
View file

@ -1918,7 +1918,11 @@
// (x & ac) >> sc
(SRLconst [sc] (ANDconst [ac] x)) && isARM64BFMask(sc, ac, sc)
=> (UBFX [armBFAuxInt(sc, arm64BFWidth(ac, sc))] x)
// merge ANDconst and ubfx into ubfx
(ANDconst [c] (UBFX [bfc] x)) && isARM64BFMask(0, c, 0) =>
(UBFX [armBFAuxInt(bfc.getARM64BFlsb(), min(bfc.getARM64BFwidth(), arm64BFWidth(c, 0)))] x)
(UBFX [bfc] (ANDconst [c] x)) && isARM64BFMask(0, c, 0) && bfc.getARM64BFlsb() + bfc.getARM64BFwidth() <= arm64BFWidth(c, 0) =>
(UBFX [bfc] x)
// merge ubfx and zerso-extension into ubfx
(MOVWUreg (UBFX [bfc] x)) && bfc.getARM64BFwidth() <= 32 => (UBFX [bfc] x)
(MOVHUreg (UBFX [bfc] x)) && bfc.getARM64BFwidth() <= 16 => (UBFX [bfc] x)

36
src/cmd/compile/internal/ssa/rewriteARM64.go
View file

@ -2283,6 +2283,24 @@ func rewriteValueARM64_OpARM64ANDconst(v *Value) bool {
v.AddArg(x)
return true
}
// match: (ANDconst [c] (UBFX [bfc] x))
// cond: isARM64BFMask(0, c, 0)
// result: (UBFX [armBFAuxInt(bfc.getARM64BFlsb(), min(bfc.getARM64BFwidth(), arm64BFWidth(c, 0)))] x)
for {
c := auxIntToInt64(v.AuxInt)
if v_0.Op != OpARM64UBFX {
break
}
bfc := auxIntToArm64BitField(v_0.AuxInt)
x := v_0.Args[0]
if !(isARM64BFMask(0, c, 0)) {
break
}
v.reset(OpARM64UBFX)
v.AuxInt = arm64BitFieldToAuxInt(armBFAuxInt(bfc.getARM64BFlsb(), min(bfc.getARM64BFwidth(), arm64BFWidth(c, 0))))
v.AddArg(x)
return true
}
return false
}
func rewriteValueARM64_OpARM64ANDshiftLL(v *Value) bool {
@ -21802,6 +21820,24 @@ func rewriteValueARM64_OpARM64UBFIZ(v *Value) bool {
}
func rewriteValueARM64_OpARM64UBFX(v *Value) bool {
v_0 := v.Args[0]
// match: (UBFX [bfc] (ANDconst [c] x))
// cond: isARM64BFMask(0, c, 0) && bfc.getARM64BFlsb() + bfc.getARM64BFwidth() <= arm64BFWidth(c, 0)
// result: (UBFX [bfc] x)
for {
bfc := auxIntToArm64BitField(v.AuxInt)
if v_0.Op != OpARM64ANDconst {
break
}
c := auxIntToInt64(v_0.AuxInt)
x := v_0.Args[0]
if !(isARM64BFMask(0, c, 0) && bfc.getARM64BFlsb()+bfc.getARM64BFwidth() <= arm64BFWidth(c, 0)) {
break
}
v.reset(OpARM64UBFX)
v.AuxInt = arm64BitFieldToAuxInt(bfc)
v.AddArg(x)
return true
}
// match: (UBFX [bfc] (SRLconst [sc] x))
// cond: sc+bfc.getARM64BFwidth()+bfc.getARM64BFlsb() < 64
// result: (UBFX [armBFAuxInt(bfc.getARM64BFlsb()+sc, bfc.getARM64BFwidth())] x)

6
test/codegen/bitfield.go
View file

@ -321,6 +321,12 @@ func ubfx15(x uint64) bool {
return false
}
// merge ANDconst and ubfx into ubfx
func ubfx16(x uint64) uint64 {
// arm64:"UBFX\t[$]4, R[0-9]+, [$]6",-"AND\t[$]63"
return ((x >> 3) & 0xfff) >> 1 & 0x3f
}
// Check that we don't emit comparisons for constant shifts.
//go:nosplit
func shift_no_cmp(x int) int {