Fix structure of WhileDo graph.

runtime/vm/flow_graph_builder.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_builder.h"
 
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/code_descriptors.h"
 #include "vm/dart_entry.h"
@@ skipping 1024 matching lines @@
 
   ASSERT(!is_open());
   exit_ = exit_instruction;
 }
 
 
 // <Statement> ::= While { label:     SourceLabel
 //                         condition: <Expression>
 //                         body:      <Sequence> }
 // The fragment is composed as follows:
-// a) continue-join (optional)
-// b) loop-join
-// c) [ test ] -> (body-entry-target, loop-exit-target)
-// d) body-entry-target
-// e) [ body ] -> (loop-join)
+// a) loop-join
+// b) [ test ] -> (body-entry-target, loop-exit-target)
+// c) body-entry-target
+// d) [ body ] -> (continue-join)
+// e) continue-join -> (loop-join)
 // f) loop-exit-target
 // g) break-join (optional)
 void EffectGraphVisitor::VisitWhileNode(WhileNode* node) {
   TestGraphVisitor for_test(owner(),
                             temp_index(),
                             node->condition()->token_pos());
   node->condition()->Visit(&for_test);
   ASSERT(!for_test.is_empty());  // Language spec.
 
   EffectGraphVisitor for_body(owner(), temp_index());
   for_body.Do(
       new CheckStackOverflowComp(node->token_pos(), owner()->try_index()));
   node->body()->Visit(&for_body);
 
   // Labels are set after body traversal.
   SourceLabel* lbl = node->label();
   ASSERT(lbl != NULL);
   JoinEntryInstr* join = lbl->join_for_continue();
   if (join != NULL) {
-    Goto(join);
-    exit_ = join;
+    if (for_body.is_open()) for_body.Goto(join);
+    for_body.exit_ = join;
   }
   TieLoop(for_test, for_body);
   join = lbl->join_for_break();
   if (join != NULL) {
     Goto(join);
     exit_ = join;
   }
 }
 
 
@@ skipping 1598 matching lines @@
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len));
   OS::SNPrint(chars, len, kFormat, function_name, reason);
   const Error& error = Error::Handle(
       LanguageError::New(String::Handle(String::New(chars))));
   Isolate::Current()->long_jump_base()->Jump(1, error);
 }
 
 
 }  // namespace dart