isUndef() interface for SDNode - proposal

[delena]

Summary

I'd like to add isUndef() interface to SDNode, it is really missing for me
The code
(V1.getOpcode() == ISD::UNDEF)

will look

V1.isUndef()

What do you think?

[chandlerc]

Makes sense to me. Curious if Hal, Quentin, or others see anything wrong with this?

[qcolombet]

Makes sense to me too.

Cheers,
Q.

include/llvm/CodeGen/SelectionDAGNodes.h

public:
   // Forwarding methods - These forward to the corresponding methods in SDNode.
   inline unsigned getOpcode() const;
   inline unsigned getNumOperands() const;
   inline const SDValue &getOperand(unsigned i) const;
   inline uint64_t getConstantOperandVal(unsigned i) const;
   inline bool isTargetMemoryOpcode() const;
   inline bool isTargetOpcode() const;
   inline bool isMachineOpcode() const;
+  inline bool isUndef() const;
   inline unsigned getMachineOpcode() const;
   inline const DebugLoc &getDebugLoc() const;
   inline void dump() const;
   inline void dumpr() const;
 
   /// Return true if this operand (which must be a chain) reaches the
   /// specified operand without crossing any side-effecting instructions.
   /// In practice, this looks through token factors and non-volatile loads.
public:
 
   /// Test if this node has a target-specific
   /// memory-referencing opcode (in the \<target\>ISD namespace and
   /// greater than FIRST_TARGET_MEMORY_OPCODE).
   bool isTargetMemoryOpcode() const {
     return NodeType >= ISD::FIRST_TARGET_MEMORY_OPCODE;
   }
 
+  /// Return true if the type of the node type undefined.
+  bool isUndef() const { return NodeType == ISD::UNDEF; }
+
   /// Test if this node is a memory intrinsic (with valid pointer information).
   /// INTRINSIC_W_CHAIN and INTRINSIC_VOID nodes are sometimes created for
   /// non-memory intrinsics (with chains) that are not really instances of
   /// MemSDNode. For such nodes, we need some extra state to determine the
   /// proper classof relationship.
   bool isMemIntrinsic() const {
     return (NodeType == ISD::INTRINSIC_W_CHAIN ||
             NodeType == ISD::INTRINSIC_VOID) && ((SubclassData >> 13) & 1);
inline bool SDValue::isTargetMemoryOpcode() const {
   return Node->isTargetMemoryOpcode();
 }
 inline bool SDValue::isMachineOpcode() const {
   return Node->isMachineOpcode();
 }
 inline unsigned SDValue::getMachineOpcode() const {
   return Node->getMachineOpcode();
 }
+inline bool SDValue::isUndef() const {
+  return Node->isUndef();
+}
 inline bool SDValue::use_empty() const {
   return !Node->hasAnyUseOfValue(ResNo);
 }
 inline bool SDValue::hasOneUse() const {
   return Node->hasNUsesOfValue(1, ResNo);
 }
 inline const DebugLoc &SDValue::getDebugLoc() const {
   return Node->getDebugLoc();