[all-commits] [llvm/llvm-project] f9d4d5: [RISCV] Break the (czero_eqz x, (setne x, 0)) -> x...

[Craig Topper via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f9d4d54aa0cb6fbeee1e8744b379b1eac59c3afc
      https://github.com/llvm/llvm-project/commit/f9d4d54aa0cb6fbeee1e8744b379b1eac59c3afc
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2024-04-29 (Mon, 29 Apr 2024)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp

  Log Message:
  -----------
  [RISCV] Break the (czero_eqz x, (setne x, 0)) -> x combine into 2 combines. (#90428)

We can think of this as two separate combines

(czero_eqz x, (setne y, 0)) -> (czero_eqz x, y)
and
(czero_eqz x, x) -> x

Similary the (czero_nez x, (seteq x, 0)) -> x combine can be broken into

(czero_nez x, (seteq y, 0)) -> (czero_eqz x, y)
and
(czero_eqz x, x) -> x

isel already does the (czero_eqz x, (setne y, 0)) -> (czero_eqz x, y)
and (czero_nez x, (seteq y, 0)) -> (czero_eqz x, y) combines, but doing
them early could expose other opportunities.



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