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

[David Green via cfe-commits]

davemgreen wrote:

Without the default cost-model committed this was looking pretty bad on both Arm and AArch64, but with it it seemed OK overall. I don't think our Neon mulh optimization are as good as they could be as they came up less frequently in DAG before this.

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