[all-commits] [llvm/llvm-project] 139963: [RISCV][ISel] Fold FSGNJX idioms (#100718)

[Yingwei Zheng via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 13996378d81c8fa9a364aeaafd7382abbc1db83a
      https://github.com/llvm/llvm-project/commit/13996378d81c8fa9a364aeaafd7382abbc1db83a
  Author: Yingwei Zheng <dtcxzyw2333 at gmail.com>
  Date:   2024-07-27 (Sat, 27 Jul 2024)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/lib/Target/RISCV/RISCVISelLowering.h
    M llvm/lib/Target/RISCV/RISCVInstrInfoD.td
    M llvm/lib/Target/RISCV/RISCVInstrInfoF.td
    M llvm/lib/Target/RISCV/RISCVInstrInfoZfh.td
    M llvm/test/CodeGen/RISCV/double-arith.ll
    M llvm/test/CodeGen/RISCV/float-arith.ll
    M llvm/test/CodeGen/RISCV/half-arith.ll

  Log Message:
  -----------
  [RISCV][ISel] Fold FSGNJX idioms (#100718)

This patch folds `fmul X, (fcopysign 1.0, Y)` into `fsgnjx X, Y`. This
pattern exists in some graphics applications/math libraries.
Alive2: https://alive2.llvm.org/ce/z/epyL33

Since fpimm +1.0 is lowered to a load from constant pool after
OpLegalization, I have to introduce a new RISCVISD node FSGNJX and fold
this pattern in DAGCombine.

Closes https://github.com/dtcxzyw/llvm-opt-benchmark/issues/1072.



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