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| author | Keith Randall <khr@golang.org> | 2020-10-08 11:18:02 -0700 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2020-10-08 20:35:54 +0000 |
| commit | a4b95cd092aa10b40c6be82a3e0bf1052e27122d (patch) | |
| tree | b114756c98ac859bbd96cb32db6eaf4d9b4b91d0 /src | |
| parent | 46ab0c0c0474d38d9b924b2428f20c6da58c85fa (diff) | |
| download | go-a4b95cd092aa10b40c6be82a3e0bf1052e27122d.tar.xz | |
cmd/compile: fix incorrect comparison folding
We lost a sign extension that was necessary. The nonnegative comparison
didn't have the correct extension on it. If the larger constant is
positive, but its shorter sign extension is negative, the rule breaks.
Fixes #41872
Change-Id: I6592ef103f840fbb786bf8cb94fd8804c760c976
Reviewed-on: https://go-review.googlesource.com/c/go/+/260701
Trust: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/compile/internal/ssa/gen/AMD64.rules | 4 | ||||
| -rw-r--r-- | src/cmd/compile/internal/ssa/rewriteAMD64.go | 8 |
2 files changed, 6 insertions, 6 deletions
diff --git a/src/cmd/compile/internal/ssa/gen/AMD64.rules b/src/cmd/compile/internal/ssa/gen/AMD64.rules index 408678f054..8a253035e0 100644 --- a/src/cmd/compile/internal/ssa/gen/AMD64.rules +++ b/src/cmd/compile/internal/ssa/gen/AMD64.rules @@ -1274,8 +1274,8 @@ (CMPQconst (ANDQconst _ [m]) [n]) && 0 <= m && m < n => (FlagLT_ULT) (CMPQconst (ANDLconst _ [m]) [n]) && 0 <= m && m < n => (FlagLT_ULT) (CMPLconst (ANDLconst _ [m]) [n]) && 0 <= m && m < n => (FlagLT_ULT) -(CMPWconst (ANDLconst _ [m]) [n]) && 0 <= m && int16(m) < n => (FlagLT_ULT) -(CMPBconst (ANDLconst _ [m]) [n]) && 0 <= m && int8(m) < n => (FlagLT_ULT) +(CMPWconst (ANDLconst _ [m]) [n]) && 0 <= int16(m) && int16(m) < n => (FlagLT_ULT) +(CMPBconst (ANDLconst _ [m]) [n]) && 0 <= int8(m) && int8(m) < n => (FlagLT_ULT) // TESTQ c c sets flags like CMPQ c 0. (TESTQconst [c] (MOVQconst [d])) && int64(c) == d && c == 0 => (FlagEQ) diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go index 3d7eb8c9a4..32ef26f98d 100644 --- a/src/cmd/compile/internal/ssa/rewriteAMD64.go +++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go @@ -6886,7 +6886,7 @@ func rewriteValueAMD64_OpAMD64CMPBconst(v *Value) bool { return true } // match: (CMPBconst (ANDLconst _ [m]) [n]) - // cond: 0 <= m && int8(m) < n + // cond: 0 <= int8(m) && int8(m) < n // result: (FlagLT_ULT) for { n := auxIntToInt8(v.AuxInt) @@ -6894,7 +6894,7 @@ func rewriteValueAMD64_OpAMD64CMPBconst(v *Value) bool { break } m := auxIntToInt32(v_0.AuxInt) - if !(0 <= m && int8(m) < n) { + if !(0 <= int8(m) && int8(m) < n) { break } v.reset(OpAMD64FlagLT_ULT) @@ -8243,7 +8243,7 @@ func rewriteValueAMD64_OpAMD64CMPWconst(v *Value) bool { return true } // match: (CMPWconst (ANDLconst _ [m]) [n]) - // cond: 0 <= m && int16(m) < n + // cond: 0 <= int16(m) && int16(m) < n // result: (FlagLT_ULT) for { n := auxIntToInt16(v.AuxInt) @@ -8251,7 +8251,7 @@ func rewriteValueAMD64_OpAMD64CMPWconst(v *Value) bool { break } m := auxIntToInt32(v_0.AuxInt) - if !(0 <= m && int16(m) < n) { + if !(0 <= int16(m) && int16(m) < n) { break } v.reset(OpAMD64FlagLT_ULT) |