Since I'm obliged to work with a development OS that currently doesn't

support GraphViz, I've been using the foo->dump() facility.  This
patch is a minor rewrite to the SelectionDAG dump() stuff to make it a
little more helpful.  The existing foo->dump() functionality does not
change; this patch adds foo->dumpr().  All of this is only useful when
running LLVM under a debugger.

llvm-svn: 63736