[all-commits] [llvm/llvm-project] 79845e: [DAG] Fold setcc eq with ashr to compare to zero.

[David Green via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 79845ed6dfc6511f999d4ada21d46d971f8dd724
      https://github.com/llvm/llvm-project/commit/79845ed6dfc6511f999d4ada21d46d971f8dd724
  Author: David Green <david.green at arm.com>
  Date:   2021-09-05 (Sun, 05 Sep 2021)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
    M llvm/test/CodeGen/AArch64/select-constant-xor.ll
    M llvm/test/CodeGen/AMDGPU/select-constant-xor.ll
    M llvm/test/CodeGen/ARM/select-constant-xor.ll
    M llvm/test/CodeGen/PowerPC/select-constant-xor.ll
    M llvm/test/CodeGen/RISCV/select-constant-xor.ll
    M llvm/test/CodeGen/X86/select-constant-xor.ll

  Log Message:
  -----------
  [DAG] Fold setcc eq with ashr to compare to zero.

Pulled out of D109149, this folds set_cc seteq (ashr X, BW-1), -1 ->
set_cc setlt X, 0 to prevent some regressions later on when folding
select_cc setgt X, -1, C, ~C -> xor (ashr X, BW-1), C

Differential Revision: https://reviews.llvm.org/D109214