[llvm] [AMDGPU] Recognise bitmask operations as srcmods (PR #149110)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

Can you add some scalar test cases? Particularly for the 64-bit cases. The SALU versions do not support source modifiers, so they should not fold if it's a scalar candidate 

https://github.com/llvm/llvm-project/pull/149110