Provide function name in 'Cannot select' fatal error.

When dumping the DAG for a fatal 'Cannot select' back-end error, also
provide the name of the function the construct is in. Useful when dealing
with large testcases, as the next step is to llvm-extract the function
in question to get a small(er) testcase.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160152 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -2981,6 +2981,7 @@ void SelectionDAGISel::CannotYetSelect(SDNode *N) {
       N->getOpcode() != ISD::INTRINSIC_WO_CHAIN &&
       N->getOpcode() != ISD::INTRINSIC_VOID) {
     N->printrFull(Msg, CurDAG);
+    Msg << "\nIn function: " << MF->getFunction()->getName();
   } else {
     bool HasInputChain = N->getOperand(0).getValueType() == MVT::Other;
     unsigned iid =