[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#931175, @zvi wrote:

> One option is to run llc with -O0 which will disable passes which use InstructionSimplify, but this will require changing the CHECK's to expect different generated code. If the purpose of the test is to not crash in the Verifier, are the CHECK's needed?


The checks probably aren't needed, but if this is eliminated in the IR the test isn't reaching the point it needs to. Is there another way to sneak an undef index in? i.e. some sequence that will fold to undef in the DAG that InstructionSimplify won't catch


https://reviews.llvm.org/D40231