[PATCH] D87972: [OldPM] Pass manager: run SROA after (simple) loop unrolling

[Dave Green via Phabricator via llvm-commits]

dmgreen added a comment.

> @dmgreen for arm?:)

This would seem more like a good general codegen cleanup than something that would be target dependent. It would probably be more dependent on the code that is being run, than the exact target. But yeah, I ran some baremetal tests. Only one changed (including in all the codesize tests), which was a nasty complicated state machine. It changed between -5% and +3.5%, depend on the cpu it ran on. (Unfortunately it went down on the cores I was more interested in).

I have run into this exact problem recently and very nearly put up a very similar patch for it. In that case it was making intrinsic MVE code much easier to write, as you could rely on loops not clogging up stack array uses after they were unrolled. The differences were not quite in the 160% range, but they would be nice improvements.

So, a little reluctantly, this does sound like a good idea to me. I asked Sanne to run Spec too if he has the time.


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https://reviews.llvm.org/D87972