[all-commits] [llvm/llvm-project] b705fe: [TargetLowering][X86] TeachSimplifyDemandedBits to...

[topperc via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: b705fe5686a886e200fd57410c6bc9bad5c21c0e
      https://github.com/llvm/llvm-project/commit/b705fe5686a886e200fd57410c6bc9bad5c21c0e
  Author: Craig Topper <craig.topper at intel.com>
  Date:   2020-01-09 (Thu, 09 Jan 2020)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
    M llvm/test/CodeGen/X86/vec_int_to_fp.ll

  Log Message:
  -----------
  [TargetLowering][X86] TeachSimplifyDemandedBits to handle cases where only the sign bit is demanded from a SETCC and can be passed through

If we're doing a compare that only tests the sign bit and only the sign bit is demanded, we can just bypass the node. This removes one of the blend dependencies in our v2i64->v2f32 uint_to_fp codegen on pre-sse4.2 targets.

Differential Revision: https://reviews.llvm.org/D72356