[PATCH] D40177: performance improvements for ThunderX2 T99

[Stefan Teleman via Phabricator via llvm-commits]

steleman added a comment.

> Also if I understand correctly, this should have an impact on scheduling instructions using WriteAtomic, like CASB.

It doesn't. Maybe it was supposed to, in theory, but in reality it makes no difference whatsoever.

The only noticeable difference is in instruction cost: when Unsupported == 1, the estimated instruction cost is higher than when Unsupported == 0. Which makes no difference whatsoever in practice, given that the real cost of LSE instructions is pretty high anyway.

We've been emitting LSE instructions with no problems for many months. Whether or not Unsupported was 0 or 1 made no difference whatsoever.


Repository:
  rL LLVM

https://reviews.llvm.org/D40177