[PATCH] D129947: [X86] Prefer `lock or` over mfence.

[Valentin Churavy via Phabricator via llvm-commits]

vchuravy added a comment.

We talked at LLVMdev and the reason why it wasn't done where non-temporal memory ops. The LLVM langref and the C standard says nothing about them, but currently this is the only way to obtain a fence operation that affects them.

They asked me to do a bit of canvasing to find out if folks rely on this and/or wait to see how the GCC change shake out.


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https://reviews.llvm.org/D129947