[llvm] [X86] Recognise VPMADD52L pattern with AVX512IFMA/AVXIFMA (#153787) (PR #156714)

[Justin Riddell via llvm-commits]

Arghnews wrote:

Have addressed feedback and implemented changes, have split it over 2 commits to try and make the diff easier too etc. (hope that's what you meant @XChy )

Appreciate the feedback from both. Apologies, I did try and follow conventions on things like numbered variable names in tests or attributes, I just searched for others existing in the repo which they do, and presumed it was therefore acceptable (but I guess it is a large repo and has evolved over time presumably etc.)

Setting back to review

https://github.com/llvm/llvm-project/pull/156714