[PATCH] D112734: [SCEVExpander] Drop poison generating flags when reusing instructions
Max Kazantsev via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Sun Nov 7 21:35:06 PST 2021
mkazantsev added inline comments.
================
Comment at: llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp:1947
+ !programUndefinedIfPoison(I))
+ I->dropPoisonGeneratingFlags();
+
----------------
reames wrote:
> mkazantsev wrote:
> > Will we drop flags if both copies had them?
> What do you mean by "both copies"?
The comment before this code mentions that we are CSEing two copies of same instruction with potentially different flags, and drop them if we failed to prove legality. But what if both of these copies had the same flags, do we still need to try to prove something and drop the flags? Why?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D112734/new/
https://reviews.llvm.org/D112734
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