[llvm] [AMDGPU] Emit b32 movs if (a)v_mov_b64_pseudo dest vgprs are misaligned (PR #160547)

[Jay Foad via llvm-commits]

jayfoad wrote:

> machine-cp would then allow the misaligned vgpr pair to be copy-propagated a V_MOV_B64_PSEUDO which required align2.

That doesn't sound right - if V_MOV_B64_PSEUDO uses aligned register classes then machine-cp should not do this, because it should be checking register class constraints?

https://github.com/llvm/llvm-project/pull/160547