[PATCH] D96881: [InstCombine] Avoid Bitcast-GEP fusion for pointers directly from allocation functions

Tue Mar 23 14:38:37 PDT 2021

nikic added a comment.

In D96881#2646035 <https://reviews.llvm.org/D96881#2646035>, @echristo wrote:

> In D96881#2627389 <https://reviews.llvm.org/D96881#2627389>, @nikic wrote:
>
>> LGTM per above discussion. It's not ideal, but I think it's the best we can do right now.
>
> Hi All,
>
> I'm seeing a rather numerous set of performance degredations and code size increases on x86 with this patch. I think that's a little unexpected, but do we have benchmarks and runs showing that this is a profitable change to happen in general?

If you're seeing widespread regressions, let's revert this change. My assumption here was that it would fix the motivational case without impacting anything else much, but apparently that's not the case.

If you have any information on the reason for the regression(s), that would of course the great.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D96881/new/

https://reviews.llvm.org/D96881