[PATCH] D97244: [SimplifyCFG] Update passingValueIsAlwaysUndefined to check more attributes

[Juneyoung Lee via Phabricator via llvm-commits]

aqjune added a comment.

@spatel Now I fully got what https://reviews.llvm.org/D96663#2578814 meant. This change is introducing assume because it introduces unreachable which finally turns into assume.

But, an ongoing clang frontend patch will introduce many more noundefs, and this will anyway create assumes;
If the assumes inserted by this patch cause problems, it is likely that the problems will happen with the noundef patch as well. I think it is about facing the problem earlier or not.

If we decide to be lightweight (and not to insert assume), I'll move towards SimplifyCFG to simply swap the phi's operand with undef if nonnull without noundef is met.


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  https://reviews.llvm.org/D97244/new/

https://reviews.llvm.org/D97244