[llvm] [LLVM] treat `@llvm.ssub.sat` the same as `@llvm.aarch64.neon.sqsub` (PR #140454)

[David Green via llvm-commits]

davemgreen wrote:

> Also a bunch of the ; CHECK-GI-NEXT:  warning: lines added in the first command have disappeared when I run the tests now?!

That sounds good - it mean that GISel is falling back to SDAG less often. If the tests are less efficient (for the CHECK-GI lines) that's OK if it is falling back less. There are a number of issues in gisel that we are still working through.

https://github.com/llvm/llvm-project/pull/140454