cmd/compile: avoid extending when already sufficiently shifted on loong64

This reduces 744 instructions from the go toolchain binary on loong64.

	file         before      after      Δ       %
	asm          599282      599222   -60    -0.0100%
	cgo          513606      513534   -72    -0.0140%
	compile      2939250     2939146  -104   -0.0035%
	cover        564136      564056   -80    -0.0142%
	fix          895622      895546   -76    -0.0085%
	link         759460      759376   -84    -0.0111%
	preprofile   264960      264916   -44    -0.0166%
	vet          869964      869888   -76    -0.0087%
	go           1712990     1712890  -100   -0.0058%
	gofmt        346416      346368   -48    -0.0139%
	total        9465686     9464942  -744   -0.0079%

Change-Id: I32dfa7506d0458ca0b6de83b030c330cd2b82176
Reviewed-on: https://go-review.googlesource.com/c/go/+/725720
Auto-Submit: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
This commit is contained in:
Xiaolin Zhao
2025-12-01 14:46:23 +08:00
committed by Gopher Robot
parent c04335e33a
commit 021d5ca042
2 changed files with 45 additions and 0 deletions

View File

@@ -843,6 +843,11 @@
(MOVBUreg (ANDconst [c] x)) => (ANDconst [c&0xff] x)
// Avoid extending when already sufficiently shifted.
(MOVBUreg x:(SRLconst [c] y)) && c >= 24 => x
(MOVHUreg x:(SRLconst [c] y)) && c >= 16 => x
(MOVWUreg x:(SRLconst [c] y)) => x
// Avoid extending when already sufficiently masked.
(MOVBreg x:(ANDconst [c] y)) && c >= 0 && int64(int8(c)) == c => x
(MOVHreg x:(ANDconst [c] y)) && c >= 0 && int64(int16(c)) == c => x

View File

@@ -2677,6 +2677,21 @@ func rewriteValueLOONG64_OpLOONG64MOVBUreg(v *Value) bool {
v.AddArg(x)
return true
}
// match: (MOVBUreg x:(SRLconst [c] y))
// cond: c >= 24
// result: x
for {
x := v_0
if x.Op != OpLOONG64SRLconst {
break
}
c := auxIntToInt64(x.AuxInt)
if !(c >= 24) {
break
}
v.copyOf(x)
return true
}
// match: (MOVBUreg x:(ANDconst [c] y))
// cond: c >= 0 && int64(uint8(c)) == c
// result: x
@@ -4067,6 +4082,21 @@ func rewriteValueLOONG64_OpLOONG64MOVHUreg(v *Value) bool {
v.AuxInt = int64ToAuxInt(int64(uint16(c)))
return true
}
// match: (MOVHUreg x:(SRLconst [c] y))
// cond: c >= 16
// result: x
for {
x := v_0
if x.Op != OpLOONG64SRLconst {
break
}
c := auxIntToInt64(x.AuxInt)
if !(c >= 16) {
break
}
v.copyOf(x)
return true
}
// match: (MOVHUreg x:(ANDconst [c] y))
// cond: c >= 0 && int64(uint16(c)) == c
// result: x
@@ -5301,6 +5331,16 @@ func rewriteValueLOONG64_OpLOONG64MOVWUreg(v *Value) bool {
v.AuxInt = int64ToAuxInt(int64(uint32(c)))
return true
}
// match: (MOVWUreg x:(SRLconst [c] y))
// result: x
for {
x := v_0
if x.Op != OpLOONG64SRLconst {
break
}
v.copyOf(x)
return true
}
// match: (MOVWUreg x:(ANDconst [c] y))
// cond: c >= 0 && int64(uint32(c)) == c
// result: x