[PATCH] D105338: [InstCombine] Revert "Temporarily do not drop volatile stores before unreachable"

[Chandler Carruth via Phabricator via llvm-commits]

chandlerc added a comment.

In D105338#2863604 <https://reviews.llvm.org/D105338#2863604>, @jdoerfert wrote:

> We actually hit this in the OpenMP device runtime. It seems nobody is interested in discussing a LangRef change. LGTM assuming there is no LangRef patch by Friday.

As I said in the review thread of the prior patch -- I don't have a strong opinion about the LLVM IR semantics here.

But just reverting this is pretty hostile unless Clang has been updated to make C and C++ volatile stores continue to behave as the language expects first.

Just regressing Clang because no one has written the LangRef change doesn't make sense to me. I think you should fix Clang to not be buggy first if you want to pursue this (or work with the Clang devs to get such a patch), just like we would fix a buggy LLVM pass that broke real users before enabling a valid optimization that uncovered the big.


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https://reviews.llvm.org/D105338