[PATCH] D78502: [ARM][HWLoops] Create hardware loops for sibling loops

Fri Jul 3 18:22:26 PDT 2020

shchenz added a comment.

In D78502#2130442 <https://reviews.llvm.org/D78502#2130442>, @dmgreen wrote:

> Hello. Sorry for the delay.
>
> It turns out this patch, when run over all our benchmarks, was actually making things worse not better! The setup cost of the loop counter (from the expanded SCEV) can end up taking longer than you save for loops with a low iteration count. And I don't have a great way to mitigate that at the moment.
>
> It's still something we obviously need though, and it's not the fault of this patch exactly that it's getting worse. I'll get the patch committed and see if there's anything we can do about the problems at a later point.

Thank you!

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https://reviews.llvm.org/D78502