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| author | David Chase <drchase@google.com> | 2020-12-30 12:05:57 -0500 |
|---|---|---|
| committer | David Chase <drchase@google.com> | 2021-01-13 02:40:43 +0000 |
| commit | 9a19481acb93114948503d935e10f6985ff15843 (patch) | |
| tree | bdccf0f8413dfb40ca93862f642968229fc35a26 /src/cmd/compile/internal/ssa/rewriteAMD64.go | |
| parent | d9acf6f3a3758c3096ee5ef5a24c2bc5df9d9c8b (diff) | |
| download | go-9a19481acb93114948503d935e10f6985ff15843.tar.gz go-9a19481acb93114948503d935e10f6985ff15843.zip | |
[dev.regabi] cmd/compile: make ordering for InvertFlags more stable
Current many architectures use a rule along the lines of
// Canonicalize the order of arguments to comparisons - helps with CSE.
((CMP|CMPW) x y) && x.ID > y.ID => (InvertFlags ((CMP|CMPW) y x))
to normalize comparisons as much as possible for CSE. Replace the
ID comparison with something less variable across compiler changes.
This helps avoid spurious failures in some of the codegen-comparison
tests (though the current choice of comparison is sensitive to Op
ordering).
Two tests changed to accommodate modified instruction choice.
Change-Id: Ib35f450bd2bae9d4f9f7838ceaf7ec682bcf1e1a
Reviewed-on: https://go-review.googlesource.com/c/go/+/280155
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Diffstat (limited to 'src/cmd/compile/internal/ssa/rewriteAMD64.go')
| -rw-r--r-- | src/cmd/compile/internal/ssa/rewriteAMD64.go | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go index 75d4ff7357..db2dc7a004 100644 --- a/src/cmd/compile/internal/ssa/rewriteAMD64.go +++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go @@ -6749,12 +6749,12 @@ func rewriteValueAMD64_OpAMD64CMPB(v *Value) bool { return true } // match: (CMPB x y) - // cond: x.ID > y.ID + // cond: canonLessThan(x,y) // result: (InvertFlags (CMPB y x)) for { x := v_0 y := v_1 - if !(x.ID > y.ID) { + if !(canonLessThan(x, y)) { break } v.reset(OpAMD64InvertFlags) @@ -7135,12 +7135,12 @@ func rewriteValueAMD64_OpAMD64CMPL(v *Value) bool { return true } // match: (CMPL x y) - // cond: x.ID > y.ID + // cond: canonLessThan(x,y) // result: (InvertFlags (CMPL y x)) for { x := v_0 y := v_1 - if !(x.ID > y.ID) { + if !(canonLessThan(x, y)) { break } v.reset(OpAMD64InvertFlags) @@ -7544,12 +7544,12 @@ func rewriteValueAMD64_OpAMD64CMPQ(v *Value) bool { return true } // match: (CMPQ x y) - // cond: x.ID > y.ID + // cond: canonLessThan(x,y) // result: (InvertFlags (CMPQ y x)) for { x := v_0 y := v_1 - if !(x.ID > y.ID) { + if !(canonLessThan(x, y)) { break } v.reset(OpAMD64InvertFlags) @@ -8106,12 +8106,12 @@ func rewriteValueAMD64_OpAMD64CMPW(v *Value) bool { return true } // match: (CMPW x y) - // cond: x.ID > y.ID + // cond: canonLessThan(x,y) // result: (InvertFlags (CMPW y x)) for { x := v_0 y := v_1 - if !(x.ID > y.ID) { + if !(canonLessThan(x, y)) { break } v.reset(OpAMD64InvertFlags) |