diff --git a/include/llvm/CodeGen/SelectionDAGNodes.h b/include/llvm/CodeGen/SelectionDAGNodes.h
index ce84ed00b12..a688a9f5af7 100644
--- a/include/llvm/CodeGen/SelectionDAGNodes.h
+++ b/include/llvm/CodeGen/SelectionDAGNodes.h
@@ -1500,7 +1500,10 @@ public:
   /// We leave the version with the double argument here because it's just so
   /// convenient to write "2.0" and the like.  Without this function we'd 
   /// have to duplicate its logic everywhere it's called.
-  bool isExactlyValue(double V) const { 
+  bool isExactlyValue(double V) const {
+    // convert is not supported on this type
+    if (&Value.getSemantics() == &APFloat::PPCDoubleDouble)
+      return false;
     APFloat Tmp(V);
     Tmp.convert(Value.getSemantics(), APFloat::rmNearestTiesToEven);
     return isExactlyValue(Tmp);
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index fa38c508486..90d64832d71 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -74,12 +74,9 @@ bool ConstantFPSDNode::isValueValidForType(MVT::ValueType VT,
                                            const APFloat& Val) {
   assert(MVT::isFloatingPoint(VT) && "Can only convert between FP types");
   
-  // Anything can be extended to ppc long double.
-  if (VT == MVT::ppcf128)
-    return true;
-  
-  // PPC long double cannot be shrunk to anything though.
-  if (&Val.getSemantics() == &APFloat::PPCDoubleDouble)
+  // PPC long double cannot be converted to any other type.
+  if (VT == MVT::ppcf128 ||
+      &Val.getSemantics() == &APFloat::PPCDoubleDouble)
     return false;
   
   // convert modifies in place, so make a copy.