[clang] [llvm] [InstCombine] Combine ((ext(A) * ext(B)) >> N) -> ext(mulh(A, B)). (PR #224311)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon approved this pull request.

LGTM - we do see examples of trunc(rightshift(ext(A) * ext(B))) extending to larger than 2*bitwidth types as well, but we can't easily handle that with this pattern.

https://github.com/llvm/llvm-project/pull/224311