[PATCH] D110069: AArch64: use `CAS` instead of `LDX`/`STX` for more ops if available

[Eli Friedman via Phabricator via llvm-commits]

efriedma accepted this revision.
efriedma added a comment.

Please fix the commit message to fix the incorrect claim that this reduces codesize; the only case that actually decreases in size is the atomic load.

Please file a followup bug for the extra mov instructions.

Otherwise LGTM, I guess; improving the performance under contention probably outweighs any inefficiency caused by the extra instructions.

(We might also want to mess with the code sequences for outlining, but that doesn't need to be this patch.)


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https://reviews.llvm.org/D110069