[llvm] [X86][X86CompressEVEX] Do not compress when there is a compressed disp8 (PR #221923)

[Phoebe Wang via llvm-commits]

phoebewang wrote:

> Can we find a way to share the check with the code already present in `X86BaseInfo.h` ?

I had a try, but found it's not quite clear. In CompressEVEXImpl we have checked EVEX in advance, while in emitMemModRMByte they are mem and imm. So we have to do extra checks respectively anyway. And the shared part is straightforward, so I think it won't worth it.

https://github.com/llvm/llvm-project/pull/221923