[PATCH] D25685: [DAG] use isConstOrConstSplat in ComputeNumSignBits to optimize SRA

[Sanjay Patel via llvm-commits]

spatel added a comment.

More consolidation is possible with the ISD namespace helpers, or should the previously listed functions go here too?

  namespace ISD {
  /// Node predicates
  
  /// If N is a BUILD_VECTOR node whose elements are all the same constant or
  /// undefined, return true and return the constant value in \p SplatValue.
  bool isConstantSplatVector(const SDNode *N, APInt &SplatValue);
  
  /// Return true if the specified node is a BUILD_VECTOR where all of the
  /// elements are ~0 or undef.
  bool isBuildVectorAllOnes(const SDNode *N);
  
  /// Return true if the specified node is a BUILD_VECTOR where all of the
  /// elements are 0 or undef.
  bool isBuildVectorAllZeros(const SDNode *N);
  
  /// Return true if the specified node is a BUILD_VECTOR node of all
  /// ConstantSDNode or undef.
  bool isBuildVectorOfConstantSDNodes(const SDNode *N);
  
  /// Return true if the specified node is a BUILD_VECTOR node of all
  /// ConstantFPSDNode or undef.
  bool isBuildVectorOfConstantFPSDNodes(const SDNode *N);
  
  /// Return true if the node has at least one operand and all operands of the
  /// specified node are ISD::UNDEF.
  bool allOperandsUndef(const SDNode *N);
  }  // end llvm:ISD namespace


https://reviews.llvm.org/D25685