Followup to 72b776168c7c80d2035c7226488462dcffc97e75
Adding some vector folks to review the change of masked out lanes from undef to poison.
Langref doesn't specify a version without a pass-through argument, so this is up to the users of these functions. We need review for:
- SLP vectorizer
- Loop vectorizer
- Codegen's expand vp
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?
Thanks for the review, Simon!
I've implemented the change to LangRef here: https://github.com/llvm/llvm-project/commit/32b1b06b7081bd722750c6f3d528336f3f7ed34b
This patch can now proceed. Thank you!