[llvm] [AMDGPU] Improve selection of ballot.i64 intrinsic in wave32 mode in SelectionDAG. (PR #71556)

[Valery Pykhtin via llvm-commits]

vpykhtin wrote:

Reimplemented using instcombine rule. I had to move i64/wave32 tests to the existing dedicated test.

Please see the differences for individual commits in this branch to follow the changes made.



https://github.com/llvm/llvm-project/pull/71556