[PATCH] D52570: [X86] Don't generate BMI BEXTR from X86DAGToDAGISel::matchBEXTRFromAnd

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added a comment.

The code that led to PR38938 saw a perf improvement by moving to BEXTR on btver2 - both from the load-folding and hoisting the control constant out of the loop.

I'd really like to avoid yet another fast/slow feature flag but there might not be a better way right now if you want to get this in - @andreadb any thoughts?

https://godbolt.org/z/zdktz_


https://reviews.llvm.org/D52570