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cmd/compile: fix incorrect truncating when converting CMP to TST on arm64

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CL 420434 optimized CMP into TST in some situations, but it has a bug,
these four rules are not correct:
(LessThan (CMPWconst [0] x:(ANDconst [c] y))) && x.Uses == 1 => (LessThan (TSTconst [c] y))
(LessEqual (CMPWconst [0] x:(ANDconst [c] y))) && x.Uses == 1 => (LessEqual (TSTconst [c] y))
(GreaterThan (CMPWconst [0] x:(ANDconst [c] y))) && x.Uses == 1 => (GreaterThan (TSTconst [c] y))
(GreaterEqual (CMPWconst [0] x:(ANDconst [c] y))) && x.Uses == 1 => (GreaterEqual (TSTconst [c] y))

But due to the existence of this rule
(LessThan (CMPWconst [0] x:(ANDconst [c] y))) && x.Uses == 1 =>
(LessThan (TSTWconst [int32(c)] y)), the above rules have never been
fired. This CL corrects them as:
(LessThan (CMPconst [0] x:(ANDconst [c] y))) && x.Uses == 1 => (LessThan (TSTconst [c] y))
(LessEqual (CMPconst [0] x:(ANDconst [c] y))) && x.Uses == 1 => (LessEqual (TSTconst [c] y))
(GreaterThan (CMPconst [0] x:(ANDconst [c] y))) && x.Uses == 1 => (GreaterThan (TSTconst [c] y))
(GreaterEqual (CMPconst [0] x:(ANDconst [c] y))) && x.Uses == 1 => (GreaterEqual (TSTconst [c] y))

Change-Id: I7d60bcc9a266ee58388baeaab9f493b57cf1ad55
Reviewed-on: https://go-review.googlesource.com/c/go/+/473617
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Eric Fang <eric.fang@arm.com>
This commit is contained in:
erifan01
2023-03-07 08:44:08 +08:00
committed by Eric Fang
parent ed2442a0e1
commit 91a2e921dd
3 changed files with 16 additions and 12 deletions
src/cmd/compile/internal/ssa
_gen
ARM64.rules
rewriteARM64.go
test/codegen
comparisons.go

4
test/codegen/comparisons.go

@ -234,6 +234,8 @@ func CmpToZero(a, b, d int32, e, f int64, deOptC0, deOptC1 bool) int32 {
c7 := e&(f<<3) < 0
// arm64:`CMN\sR[0-9]+<<3,\sR[0-9]+`
c8 := e+(f<<3) < 0
// arm64:`TST\sR[0-9],\sR[0-9]+`
c9 := e&17 < 0
if c0 {
return 1
} else if c1 {
@ -252,6 +254,8 @@ func CmpToZero(a, b, d int32, e, f int64, deOptC0, deOptC1 bool) int32 {
return 9
} else if c8 {
return 10
} else if c9 {
return 11
} else if deOptC0 {
return b + d
} else if deOptC1 {