[PATCH] D93946: [FuncAttrs] Infer noreturn

Thu Jan 14 05:53:29 PST 2021

sanwou01 added a comment.

In D93946#2493599 <https://reviews.llvm.org/D93946#2493599>, @sanwou01 wrote:

> In D93946#2493440 <https://reviews.llvm.org/D93946#2493440>, @aeubanks wrote:
>
>> Could you do some initial investigation or come up with a repro? Maybe an optimization remark that doesn't fire after this change?
>
> Yes, I will do an initial investigation, hopefully resulting in a reproducer. It is always a bit of a challenge with LTO benchmarks, but the regression is large enough that it should be easy to spot.

This appears to be a (very painful) second order effect that is causing an increase in branch misses in one of the loops in h264ref. There is no codegen difference in the area, only a slight change in alignment. So nothing to do with this patch really, just bad luck.

Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D93946