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| author | Keith Randall <khr@golang.org> | 2021-09-19 09:23:37 -0700 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2021-09-19 23:50:45 +0000 |
| commit | 315dbd10c90db3b41af2c975a5fbfa2ec7615c1b (patch) | |
| tree | abeeee7d13f3d084e9b027edd4b48cedeb1bb7ab | |
| parent | 83b36ffb108cc6e6cc3282b94c090f70100b5ef0 (diff) | |
| download | go-315dbd10c90db3b41af2c975a5fbfa2ec7615c1b.tar.gz go-315dbd10c90db3b41af2c975a5fbfa2ec7615c1b.zip | |
cmd/compile: fold double negate on arm64
Fixes #48467
Change-Id: I52305dbf561ee3eee6c1f053e555a3a6ec1ab892
Reviewed-on: https://go-review.googlesource.com/c/go/+/350910
Trust: Keith Randall <khr@golang.org>
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
| -rw-r--r-- | src/cmd/compile/internal/ssa/gen/ARM64.rules | 1 | ||||
| -rw-r--r-- | src/cmd/compile/internal/ssa/rewriteARM64.go | 10 | ||||
| -rw-r--r-- | test/codegen/bits.go | 8 |
3 files changed, 19 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/gen/ARM64.rules b/src/cmd/compile/internal/ssa/gen/ARM64.rules index f63b2557c5..23ae3b1286 100644 --- a/src/cmd/compile/internal/ssa/gen/ARM64.rules +++ b/src/cmd/compile/internal/ssa/gen/ARM64.rules @@ -1363,6 +1363,7 @@ (XOR x (MVN y)) => (EON x y) (OR x (MVN y)) => (ORN x y) (MVN (XOR x y)) => (EON x y) +(NEG (NEG x)) => x (CSEL [cc] (MOVDconst [-1]) (MOVDconst [0]) flag) => (CSETM [cc] flag) (CSEL [cc] (MOVDconst [0]) (MOVDconst [-1]) flag) => (CSETM [arm64Negate(cc)] flag) diff --git a/src/cmd/compile/internal/ssa/rewriteARM64.go b/src/cmd/compile/internal/ssa/rewriteARM64.go index 2bce96f0b2..661714307a 100644 --- a/src/cmd/compile/internal/ssa/rewriteARM64.go +++ b/src/cmd/compile/internal/ssa/rewriteARM64.go @@ -15691,6 +15691,16 @@ func rewriteValueARM64_OpARM64NEG(v *Value) bool { v.AddArg2(x, y) return true } + // match: (NEG (NEG x)) + // result: x + for { + if v_0.Op != OpARM64NEG { + break + } + x := v_0.Args[0] + v.copyOf(x) + return true + } // match: (NEG (MOVDconst [c])) // result: (MOVDconst [-c]) for { diff --git a/test/codegen/bits.go b/test/codegen/bits.go index 8117a62307..8e973d5726 100644 --- a/test/codegen/bits.go +++ b/test/codegen/bits.go @@ -6,6 +6,8 @@ package codegen +import "math/bits" + /************************************ * 64-bit instructions ************************************/ @@ -355,3 +357,9 @@ func issue44228b(a []int32, i int) bool { // amd64: "BTL", -"SHL" return a[i>>5]&(1<<(i&31)) != 0 } + +func issue48467(x, y uint64) uint64 { + // arm64: -"NEG" + d, borrow := bits.Sub64(x, y, 0) + return x - d&(-borrow) +} |