[llvm] [GlobalISel] Skip match table for opcodes with no combines (PR #196017)

[Cullen Rhodes via llvm-commits]

c-rhodes wrote:

> getRegBankInfo, getRegisterInfo etc. are virtual function calls. IMO, none of these should be virtual function calls?

I've posted a potential fix #196530, not sure if you had something else in mind but this seems like an easy fix given how CombineHelper is already structured.

> executeMatchTable's Flags and NoFPException could be sunken into propagateFlags, which is called at most once.

I'm not seeing any improvement for this

https://github.com/llvm/llvm-project/pull/196017