[llvm] Improve selection of conditional branch on amdgcn.ballot!=0 condition in SelectionDAG. (PR #68714)

[Valery Pykhtin via llvm-commits]

https://github.com/vpykhtin commented:

I've added support for negated ballot but I had to simulate it using llvm.amdgcn.icmp intrinsic.

Tests for GlobalISel aren't added because they fail on "cannot select llvm.amdgcn.icmp(i1 ...)"



https://github.com/llvm/llvm-project/pull/68714