Introduce Goto instructions to the flow graph.

runtime/vm/flow_graph_builder.h

Index: runtime/vm/flow_graph_builder.h
diff --git a/runtime/vm/flow_graph_builder.h b/runtime/vm/flow_graph_builder.h
index fe4585dfd368cf1b2b6b4347943a3f36adb00189..aa54d97ab103ff7c91fc8ea6519292059eaa2cb7 100644
--- a/runtime/vm/flow_graph_builder.h
+++ b/runtime/vm/flow_graph_builder.h
@@ -125,6 +125,9 @@ class EffectGraphVisitor : public AstNodeVisitor {
   // Append a single (non-Bind, non-Do) instruction.  Assumes this graph is
   // open.

[srdjan, 2012/07/12 16:42:26]

Adapt comment to changed AddInstruction.

   void AddInstruction(Instruction* instruction);
+  // Append a Goto (unconditional control flow) instruction and close
+  // the graph fragment.  Assumes this graph fragment is open.
+  void Goto(JoinEntryInstr* join);

[srdjan, 2012/07/12 16:42:26]

IMO, s/Goto/AppendGotoTo/ makes it more reable at call site

[Kevin Millikin (Google), 2012/07/13 15:34:59]

I see your point.  Goto is what happens at runtime, not an effect on the graph.

On the other hand, "AppendGotoTo" is ambiguous (is is a goto to the join, or is
it appended to the join?).  And we're doing a bit more than just adding a single
instruction.

So I'm happy to have it changed to a better name, but I've left it as "Goto" for
now.

 
   // Append a 'diamond' branch and join to this graph, depending on which
   // parts are reachable.  Assumes this graph is open.