[PATCH] D138526: [SimpleLoopUnswitch] unswitch selects

Mon May 1 10:34:29 PDT 2023

vitalybuka added a comment.

In D138526#4310137 <https://reviews.llvm.org/D138526#4310137>, @caojoshua wrote:

> In D138526#4309373 <https://reviews.llvm.org/D138526#4309373>, @vitalybuka wrote:
>
>> In D138526#4309363 <https://reviews.llvm.org/D138526#4309363>, @caojoshua wrote:
>>
>>> Should be fixed by https://reviews.llvm.org/D149560, which does not unswitch vector selects.
>>
>> Could this be caused by this patch?
>> https://lab.llvm.org/buildbot/#/builders/74/builds/18906
>
> It first started failing in https://lab.llvm.org/buildbot/#/builders/237/builds/2419, which this patch is on the blamelist for. There are 11 patches on the blamelist, and this patch is the most disruptive. Looking at the error message, msan has found use-of-initialized error. Its not obvious to me how this patch can cause this.
>
> I will try reproducing this locally.

My nightly bisect failed. So still guesses.
instcombine cold be related too, but this one is more likely. Msan is about branches. In case of select, it only propagates shadow, but branch reports uninitialized stuff immediatly.
So either a bug in the Interval code, this patch breaks msan.

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D138526/new/

https://reviews.llvm.org/D138526