[PATCH] D40231: InstructionSimplify: 'extractelement' with an undef index is undef

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

In https://reviews.llvm.org/D40231#929842, @zvi wrote:

> Hi @arsenm,
>
> With this patch i am seeing failures in test/CodeGen/AMDGPU/indirect-addressing-si.ll . This test include extractelement instructions with undef indices, which is what this patch targets. I would appreciate your help with advice on how we can modify these tests so that they can be used safely. Please bear in mind that i have no knowledge of the AMDGPU backend.
>
> Thanks, Zvi


I think the point of the tests was to make sure we don't hit use of undefined register errors when it's expanded . I don't think InstructionSimplify is guaranteed during codegen, so it would be nice if there was still a way to get an undef index through codegen.


https://reviews.llvm.org/D40231