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[dev.ssa] cmd/compile/internal/ssa: handle commutative operations in cse

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* If a operation is commutative order the parameters
in a canonical way.

Size of pkg/tool/linux_amd64/* excluding compile:
before: 95882288
 after: 95868152
change: 14136 ~0.015%

I tried something similar with Leq and Geq, but the results were
not great because it confuses the 'lowered cse' pass too much
which can no longer remove redundant comparisons from IsInBounds.

Change-Id: I2f928663a11320bfc51c7fa47e384b7411c420ba
Reviewed-on: https://go-review.googlesource.com/19727
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Alexandru Moșoi 2016-02-22 11:19:15 +01:00 • committed by Alexandru Moșoi
parent b86cafc7dc
commit 88c1ef5b45
5 changed files with 130 additions and 91 deletions
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4
src/cmd/compile/internal/ssa/cse.go
View file

@ -35,6 +35,10 @@ func cse(f *Func) {
if v.Type.IsMemory() {
continue // memory values can never cse
}
if opcodeTable[v.Op].commutative && len(v.Args) == 2 && v.Args[1].ID < v.Args[0].ID {
// Order the arguments of binary commutative operations.
v.Args[0], v.Args[1] = v.Args[1], v.Args[0]
}
a = append(a, v)
}
}