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cmd/compile: convert branch with zero to more optimal branch zero on riscv64

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Convert BLT and BGE with a zero valued constant to BGTZ/BLTZ/BLEZ/BGEZ as
appropriate.

Removes over 4,500 instructions from the go binary on riscv64.

Change-Id: Icc266e968b126ba04863ec88529630a9dd44498b
Reviewed-on: https://go-review.googlesource.com/c/go/+/342849
Trust: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
This commit is contained in:
Joel Sing 2021-08-17 19:01:52 +10:00
parent dcee007aad
commit bcd146d398
2 changed files with 51 additions and 1 deletions
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6
src/cmd/compile/internal/ssa/gen/RISCV64.rules
View File

@ -596,11 +596,15 @@
(BEQZ (SLTU x y) yes no) => (BGEU x y yes no)
(BNEZ (SLTU x y) yes no) => (BLTU x y yes no)
// Convert branch with zero to BEQZ/BNEZ.
// Convert branch with zero to more optimal branch zero.
(BEQ (MOVDconst [0]) cond yes no) => (BEQZ cond yes no)
(BEQ cond (MOVDconst [0]) yes no) => (BEQZ cond yes no)
(BNE (MOVDconst [0]) cond yes no) => (BNEZ cond yes no)
(BNE cond (MOVDconst [0]) yes no) => (BNEZ cond yes no)
(BLT (MOVDconst [0]) cond yes no) => (BGTZ cond yes no)
(BLT cond (MOVDconst [0]) yes no) => (BLTZ cond yes no)
(BGE (MOVDconst [0]) cond yes no) => (BLEZ cond yes no)
(BGE cond (MOVDconst [0]) yes no) => (BGEZ cond yes no)
// Store zero
(MOVBstore [off] {sym} ptr (MOVDconst [0]) mem) => (MOVBstorezero [off] {sym} ptr mem)

46
src/cmd/compile/internal/ssa/rewriteRISCV64.go
View File

@ -6129,6 +6129,52 @@ func rewriteBlockRISCV64(b *Block) bool {
b.resetWithControl2(BlockRISCV64BGEU, x, y)
return true
}
case BlockRISCV64BGE:
// match: (BGE (MOVDconst [0]) cond yes no)
// result: (BLEZ cond yes no)
for b.Controls[0].Op == OpRISCV64MOVDconst {
v_0 := b.Controls[0]
if auxIntToInt64(v_0.AuxInt) != 0 {
break
}
cond := b.Controls[1]
b.resetWithControl(BlockRISCV64BLEZ, cond)
return true
}
// match: (BGE cond (MOVDconst [0]) yes no)
// result: (BGEZ cond yes no)
for b.Controls[1].Op == OpRISCV64MOVDconst {
cond := b.Controls[0]
v_1 := b.Controls[1]
if auxIntToInt64(v_1.AuxInt) != 0 {
break
}
b.resetWithControl(BlockRISCV64BGEZ, cond)
return true
}
case BlockRISCV64BLT:
// match: (BLT (MOVDconst [0]) cond yes no)
// result: (BGTZ cond yes no)
for b.Controls[0].Op == OpRISCV64MOVDconst {
v_0 := b.Controls[0]
if auxIntToInt64(v_0.AuxInt) != 0 {
break
}
cond := b.Controls[1]
b.resetWithControl(BlockRISCV64BGTZ, cond)
return true
}
// match: (BLT cond (MOVDconst [0]) yes no)
// result: (BLTZ cond yes no)
for b.Controls[1].Op == OpRISCV64MOVDconst {
cond := b.Controls[0]
v_1 := b.Controls[1]
if auxIntToInt64(v_1.AuxInt) != 0 {
break
}
b.resetWithControl(BlockRISCV64BLTZ, cond)
return true
}
case BlockRISCV64BNE:
// match: (BNE (MOVDconst [0]) cond yes no)
// result: (BNEZ cond yes no)