Add a check to avoid allowing V->replaceAllUsesWith(V)

llvm-svn: 104

llvm/lib/VMCore/Value.cpp

@@ -43,6 +43,7 @@ Value::~Value() {
 
 void Value::replaceAllUsesWith(Value *D) {
   assert(D && "Value::replaceAllUsesWith(<null>) is invalid!");
+  assert(D != this && "V->replaceAllUsesWith(V) is NOT valid!");
   while (!Uses.empty()) {
     User *Use = Uses.front();
 #ifndef NDEBUG