[PATCH] D83745: [ARM] Optimize immediate selection

Mon Jul 27 07:55:07 PDT 2020

SjoerdMeijer added a comment.

In D83745#2175933 <https://reviews.llvm.org/D83745#2175933>, @benshi001 wrote:

> In D83745#2175668 <https://reviews.llvm.org/D83745#2175668>, @SjoerdMeijer wrote:
>
> > Eye balling the one test that was changed this indeed makes sense. But I would prefer to see some performance numbers first just to check we haven't missed anything.
>
>
> Is there a performance test suite for llvm/arm I can try? Or just a small piece of code running 1000 times is OK enough? 
>  Actually I have made similar optimization for golang, golang's official go1 benchmark score shows slight improvement.
>
> https://github.com/golang/go/commit/6897030fe3de43bbed48adb72f21a6c2d00042cd

Briefly looking at those numbers, that shows a bit of up and down behaviour. And while the geomean's show a small improvement, I don't find it quite convincing... i.e., not yet. Hence my request for some numbers. But first of all I am curious to know what causes the regressions? In other words, what are we missing with this patch, and can that be mitigated, or what kind of knock on effects does this have?
There is the llvm test-suite, see e.g. https://llvm.org/docs/TestSuiteGuide.html. If you can run that, that would be good.

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https://reviews.llvm.org/D83745