[llvm] [AMDGPU] Merge two V_CNDMASK instructions into V_DUAL_CNDMASK (PR #135007)

[Jay Foad via llvm-commits]

jayfoad wrote:

> for using vop2 instead of vop3 format

Normally this kind of shrinking would be done in SIShrinkInstructions. Is there a reason you can't do it there?

https://github.com/llvm/llvm-project/pull/135007