[all-commits] [llvm/llvm-project] 03f9e0: [TargetLowering][ARM] Don't alter opaque constants...

[Craig Topper via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 03f9e04bc35c674337ec04d629260b4a283c1f25
      https://github.com/llvm/llvm-project/commit/03f9e04bc35c674337ec04d629260b4a283c1f25
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2021-06-24 (Thu, 24 Jun 2021)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
    M llvm/test/CodeGen/ARM/select-imm.ll

  Log Message:
  -----------
  [TargetLowering][ARM] Don't alter opaque constants in TargetLowering::ShrinkDemandedConstant.

We don't constant fold based on demanded bits elsewhere in
SimplifyDemandedBits, so I don't think we should shrink them either.

The affected ARM test changes because a constant become non-opaque
and eventually enabled some constant folding. This no longer happens.
I checked and InstCombine is able to simplify this test. I'm not sure exactly
what it was trying to test.

Reviewed By: lebedev.ri, dmgreen

Differential Revision: https://reviews.llvm.org/D104832