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[DAGCombine] Do not try to deduplicate commutative operations if both operand are the same.

Authored by deadalnix on Jun 2 2017, 9:39 AM.

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deadalnix created this revision.Jun 2 2017, 9:39 AM
RKSimon edited edge metadata.Jun 2 2017, 10:17 AM

Do you have any stats?

1565 ↗(On Diff #101231)

Why you're here, please can you change this to SDISel to make it clearer.

deadalnix updated this revision to Diff 101261.Jun 2 2017, 12:30 PM

make comment clearer.

Do you have any stats?

Any compile time stats? Compiling clang before/after this patch should be good enough for an initial comparison.


I got sidetracked into some other very urgent project during June. I'll do my best to provide that number as soon as I can. I don't expect the gain, as this, to be that great, but who knows ? What I'm after here is to reduce the impact of D33587 on performances.

OK, benchmarks. Compiling clang from a bc containing clang in its entierety. With the patch:

real    9m45.457s
user    9m44.085s
sys     0m1.384s


real    9m45.521s
user    9m44.016s
sys     0m1.517s

The impact on perfs is not very significant. It's within the noise.

nemanjai edited edge metadata.Aug 11 2017, 3:14 PM

I think that as expected, this has a minimal impact on compile time. But of course, it can't hurt I suppose. I don't see why anyone would be opposed to this.

This revision was automatically updated to reflect the committed changes.