Have TableGen emit setSubgraphColor calls under control of a -gen-debug

flag.  Then in a debugger developers can set breakpoints at these calls
to see waht is about to be selected and what the resulting subgraph
looks like.  This really helps when debugging instruction selection.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58278 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86ISelDAGToDAG.cpp

@@ -655,7 +655,7 @@ void X86DAGToDAGISel::InstructionSelect() {
   DOUT << "===== Instruction selection begins:\n";
   Indent = 0;
 #endif
-  SelectRoot();
+  SelectRoot(*CurDAG);
 #ifndef NDEBUG
   DOUT << "===== Instruction selection ends:\n";
 #endif