[clang] [llvm] [AMDGPU] Remove icmp and fcmp intrinsics and builtins (PR #208183)

[Jay Foad via cfe-commits]

jayfoad wrote:

> Are ballots implicitly prevented from being moved into a predecessor or successor basic blocks with a different EXEC mask, and are CFG restructuring passes tamed around ballot to make sure they don't affect the EXEC mask for it?

Yes. The ballot intrinsic is marked as convergent, which should prevent that kind of thing. Of course there could still be bugs, but hopefully they have been flushed out by now because LLPC already uses ballot.

https://github.com/llvm/llvm-project/pull/208183