[llvm] [AMDGPU][MC] Restrict op_sel in VOP3P dot instructions (PR #100485)

[Jun Wang via llvm-commits]

jwanggit86 wrote:

> I would disallow it. Why pre-GFX11 only? It does not do anything for dot4 and dot8 on any target.

The reason for limiting this to pre-GFX11 is that Sect 7.5.1 of the RDNA3 ISA doc indicates "ignore OPSEL" for dot4_* and dot8_*, which seems to imply it's allowed. But I'm fine with disallowing it for all targets, which is actually what the 1st commit did.


https://github.com/llvm/llvm-project/pull/100485