[llvm] [AMDGPU] Create an AMDGPUIfConverter pass (PR #106415)

[Juan Manuel Martinez Caamaño via llvm-commits]

jmmartinez wrote:

@jayfoad An extract of the motivating example is this code: https://godbolt.org/z/dPdf7r381 .

This extract comes from SWDEV-477895, where CK used inline-assembly to work around code that doesn't optimize to a `v_cmpx` instruction.

https://github.com/llvm/llvm-project/pull/106415