[llvm] [AMDGPU] (x or y) xor -1 -> x nor y (PR #130264)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

Can you remodel the testing style after something like test/CodeGen/AMDGPU/GlobalISel/xnor.ll?

Notably:
wave32 and wave64 should be the same file. There is no IR difference between them.

The tested type combinations should be in the name. The wavesize is only significant to the output, not the input.

Explicit tests for the negative one use case, with a name to reflect that

Avoid memory instructions, they are not relevant to the pattern and add a lot of extra noise to the output 

https://github.com/llvm/llvm-project/pull/130264