Delete dead code in the SelectionDAG headers (NFC)

[vsk]

Summary

I tested this with "ninja check-llvm-codegen" on a Release build with
all architectures enabled.

Found with llvm-cov.

llvm/trunk/include/llvm/CodeGen/SelectionDAG.h

if (Op.getOpcode() == ISD::UNDEF) {
              "greater than the vector element type!");
       return getNode(ISD::UNDEF, SDLoc(), VT);
     }
 
     SmallVector<SDValue, 16> Ops(VT.getVectorNumElements(), Op);
     return getNode(ISD::BUILD_VECTOR, DL, VT, Ops);
   }
 
-  /// Return a splat ISD::BUILD_VECTOR node, but with Op's SDLoc.
-  SDValue getSplatBuildVector(EVT VT, SDValue Op) {
-    return getSplatBuildVector(VT, SDLoc(Op), Op);
-  }
-
   /// \brief Returns an ISD::VECTOR_SHUFFLE node semantically equivalent to
   /// the shuffle node in input but with swapped operands.
   ///
   /// Example: shuffle A, B, <0,5,2,7> -> shuffle B, A, <4,1,6,3>
   SDValue getCommutedVectorShuffle(const ShuffleVectorSDNode &SV);
 
   /// Convert Op, which must be of integer type, to the
   /// integer type VT, by either any-extending or truncating it.

llvm/trunk/include/llvm/CodeGen/SelectionDAGNodes.h

public:
   bool hasExact() const { return Exact; }
   bool hasUnsafeAlgebra() const { return UnsafeAlgebra; }
   bool hasNoNaNs() const { return NoNaNs; }
   bool hasNoInfs() const { return NoInfs; }
   bool hasNoSignedZeros() const { return NoSignedZeros; }
   bool hasAllowReciprocal() const { return AllowReciprocal; }
   bool hasVectorReduction() const { return VectorReduction; }
 
-  /// Return a raw encoding of the flags.
-  /// This function should only be used to add data to the NodeID value.
-  unsigned getRawFlags() const {
-    return (NoUnsignedWrap << 0) | (NoSignedWrap << 1) | (Exact << 2) |
-    (UnsafeAlgebra << 3) | (NoNaNs << 4) | (NoInfs << 5) |
-    (NoSignedZeros << 6) | (AllowReciprocal << 7);
-  }
-
   /// Clear any flags in this flag set that aren't also set in Flags.
   void intersectWith(const SDNodeFlags *Flags) {
     NoUnsignedWrap &= Flags->NoUnsignedWrap;
     NoSignedWrap &= Flags->NoSignedWrap;
     Exact &= Flags->Exact;
     UnsafeAlgebra &= Flags->UnsafeAlgebra;
     NoNaNs &= Flags->NoNaNs;
     NoInfs &= Flags->NoInfs;