[PATCH] D31516: Separate {Min, Max}AtomicLockFreeWidth from MaxAtomicInlineWidth

[Dan Gohman via Phabricator via llvm-commits]

sunfish added a reviewer: efriedma.
sunfish added a comment.

The perspective from the folks designing the WebAssembly memory model is that

- WebAssembly has greater backwards-compatibility requirements than LLVM does, so it needs to be more conservative, in general.
- 1-byte and 2-byte atomic operations aren't very important.

Consequently, WebAssembly intends to retain the property that 4-byte atomics are guaranteed lock-free, and 2-byte and 1-byte are not guaranteed. To implement this in clang, we'll need something like the patch here.


Repository:
  rL LLVM

https://reviews.llvm.org/D31516