[all-commits] [llvm/llvm-project] 258b54: [X86] Teach computeKnownBitsForTargetNode about MU...

kazutakahirata via All-commits all-commits at lists.llvm.org
Mon Mar 27 09:02:39 PDT 2023

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 258b5424edcf72063561ef7bb2ba6e5fbf24181a
  Author: Kazu Hirata <kazu at google.com>
  Date:   2023-03-27 (Mon, 27 Mar 2023)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/pr57402.ll
    M llvm/test/CodeGen/X86/select-constant-lea.ll

  Log Message:
  [X86] Teach computeKnownBitsForTargetNode about MUL_IMM

This patch teaches computeKnownBitsForTargetNode about MUL_IMM.

MUL_IMM comes up in certain select of constants.  Specifically, it is
used to multiply the result of SETCC.  Computing the known zero bits
of MUL_IMM allows matchAddressRecursively us to convert some OR into
ADD, which eventually becomes a part of LEA.

This patch fixes:


Differential Revision: https://reviews.llvm.org/D146787

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