[llvm] [AMDGPU] Remove SIWholeQuadMode pseudo wavemode optimization (PR #94133)

[Carl Ritson via llvm-commits]

perlfu wrote:

> Code changes look good as this is a clean revert.

It is technically one line different from a direct revert, because the original commit fixed a one line bug.

> Would it be possible to post a simple test case?

The existing if-endif cases kind of cover this, but I have added a new test which shows the issue with kill call in WQM shaders and strict WQM.

> What is "a later exec mask manipulation optimizer"?

I think there is scope for adding a exec mask analysis which could detect regions where the mask would be the same and removed unnecessary changes.
This would be separate follow up work which would safely reimplement the optimization removed with this PR.


https://github.com/llvm/llvm-project/pull/94133