[PATCH] D149935: [ValueTracking] Imply poison if ValAssumePoison is identical to V

Fri May 5 08:37:06 PDT 2023

StephenFan added a comment.

In D149935#4321253 <https://reviews.llvm.org/D149935#4321253>, @nikic wrote:

> What is the motivation for this? Generally speaking, we leave this to CSE/GVN and don't try to handle identical instructions.

There are some regressions in D149404 <https://reviews.llvm.org/D149404>. I want to solve some of these regressions in that patch. For example, test `auto_gen_5_logical_fmf` in and-fcmp.ll.
And I found that multiple instcombines would be executed before GVN. I am concerned that the regressions in D149404 <https://reviews.llvm.org/D149404> would make some redundancies no longer be optimized by GVN. But I haven't looked in depth yet.

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