[all-commits] [llvm/llvm-project] 301259: [RISCV] Teach getIntImmCostInst about (X & -(1 << ...

[Craig Topper via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 301259a6b1c8146a185e7c1bea46ec02d028243e
      https://github.com/llvm/llvm-project/commit/301259a6b1c8146a185e7c1bea46ec02d028243e
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2025-09-29 (Mon, 29 Sep 2025)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
    M llvm/test/CodeGen/RISCV/and-negpow2-cmp.ll

  Log Message:
  -----------
  [RISCV] Teach getIntImmCostInst about (X & -(1 << C1) & 0xffffffff) == C2 << C1 (#160163)

We can rewrite this to (srai(w)/srli X, C1) == C2 so the AND immediate
is free. This transform is done by performSETCCCombine in
RISCVISelLowering.cpp.

This fixes the opaque constant case mentioned in #157416.



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