[all-commits] [llvm/llvm-project] be62b3: [AArch64][GlobalISel] Add a combine to fold away t...

[AE via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: be62b3ba347d8d9e7ada364ddc9e16d7ddd05b8e
      https://github.com/llvm/llvm-project/commit/be62b3ba347d8d9e7ada364ddc9e16d7ddd05b8e
  Author: Amara Emerson <amara at apple.com>
  Date:   2021-01-28 (Thu, 28 Jan 2021)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64Combine.td
    M llvm/lib/Target/AArch64/GISel/AArch64PreLegalizerCombiner.cpp
    A llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-icmp-redundant-trunc.mir

  Log Message:
  -----------
  [AArch64][GlobalISel] Add a combine to fold away truncate in: G_ICMP EQ/NE (G_TRUNC(v), 0)

We try to do this optimization if we can determine that testing for the
truncated bits with an eq/ne predicate results in the same thing as testing
the lower bits.

Differential Revision: https://reviews.llvm.org/D95645