[all-commits] [llvm/llvm-project] cdf26f: [RISCV] Fold (add X, (mulhs X, C)) -> (mulhsu X, C...

[Craig Topper via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: cdf26f6721363d542865d826dd6455d448e1e860
      https://github.com/llvm/llvm-project/commit/cdf26f6721363d542865d826dd6455d448e1e860
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2026-06-03 (Wed, 03 Jun 2026)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/test/CodeGen/RISCV/div-by-constant.ll
    M llvm/test/CodeGen/RISCV/srem-lkk.ll
    M llvm/test/CodeGen/RISCV/srem-vector-lkk.ll

  Log Message:
  -----------
  [RISCV] Fold (add X, (mulhs X, C)) -> (mulhsu X, C) if C is negative. (#199287)

Improves some division by constant cases.

Based on this blog post
https://needlesscomplexity.substack.com/p/implementing-division-by-multiplying

Correctness proof is sketched out in the comments.



To unsubscribe from these emails, change your notification settings at https://github.com/llvm/llvm-project/settings/notifications