[PATCH] D133967: [IRBuilder] Use PoisonValue in CreateMasked*

Mon Sep 19 01:15:26 PDT 2022

simoll added a comment.

In D133967#3797505 <https://reviews.llvm.org/D133967#3797505>, @nlopes wrote:

> I reviewed all users:
>
> - SLP Vectorizer: the mask is all ones, so passthru is irrelevant
> - Loop vectorizer: masked out lanes aren't used. In fact, masked loads are already using poison for passthru.
> - X86 expand intrinsic: uses custom zero passthru.
> - Codegen expand vp load/gather: there's an issue here as langref says passthru is undef.
>
> So, vector folks, is it ok to change `@llvm.vp.load`/gather's passthru to poison instead of undef?

Yes and we should do this for all VP intrinsics. This also means we need to change the wording in the `Semantics` sections, eg https://llvm.org/docs/LangRef.html#id894 .

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D133967/new/

https://reviews.llvm.org/D133967