[all-commits] [llvm/llvm-project] db9252: DAG: Call SimplifyDemandedBits on fcopysign sign v...

[Matt Arsenault via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: db9252b115ce699a98b3a0ab80504da1364cc311
      https://github.com/llvm/llvm-project/commit/db9252b115ce699a98b3a0ab80504da1364cc311
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2024-07-01 (Mon, 01 Jul 2024)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/test/CodeGen/AMDGPU/copysign-simplify-demanded-bits.ll
    M llvm/test/CodeGen/PowerPC/fp128-bitcast-after-operation.ll
    M llvm/test/CodeGen/RISCV/double-arith.ll
    M llvm/test/CodeGen/RISCV/double-bitmanip-dagcombines.ll
    M llvm/test/CodeGen/RISCV/float-bitmanip-dagcombines.ll

  Log Message:
  -----------
  DAG: Call SimplifyDemandedBits on fcopysign sign value (#97151)

Math library code has quite a few places with complex bit
logic that are ultimately fed into a copysign. This helps
avoid some regressions in a future patch.

This assumes the position in the float type, which should
at least be valid for IEEE types. Not sure if we need to guard
against ppc_fp128 or anything else weird.

There appears to be some value in simplifying the value operand
as well, but I'll address that separately.



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