analyzer: show BBs in .dot dumps

gcc/analyzer/ChangeLog:
	* engine.cc (supernode_cluster::dump_dot): Show BB index as
	well as SN index.
	* supergraph.cc (supernode::dump_dot): Likewise.

gcc/analyzer/ChangeLog

 2020-02-03  David Malcolm  <dmalcolm@redhat.com>
 
+	* engine.cc (supernode_cluster::dump_dot): Show BB index as
+	well as SN index.
+	* supergraph.cc (supernode::dump_dot): Likewise.
+
+2020-02-03  David Malcolm  <dmalcolm@redhat.com>
+
 	PR analyzer/93546
 	* region-model.cc (region_model::on_call_pre): Update for new
 	param of symbolic_region ctor.

gcc/analyzer/engine.cc

@@ -2811,7 +2811,8 @@ public:
 		 (const void *)this);
     gv->indent ();
     gv->println ("style=\"dashed\";");
-    gv->println ("label=\"SN: %i\";", m_supernode->m_index);
+    gv->println ("label=\"SN: %i (bb: %i)\";",
+		 m_supernode->m_index, m_supernode->m_bb->index);
 
     int i;
     exploded_node *enode;

gcc/analyzer/supergraph.cc

@@ -437,7 +437,7 @@ supernode::dump_dot (graphviz_out *gv, const dump_args_t &args) const
   gv->println("style=\"solid\";");
   gv->println("color=\"black\";");
   gv->println("fillcolor=\"lightgrey\";");
-  gv->println("label=\"sn: %i\";", m_index);
+  gv->println("label=\"sn: %i (bb: %i)\";", m_index, m_bb->index);
 
   pretty_printer *pp = gv->get_pp ();