Use a local variable to save/restore the context on entry/exit, instead of

runtime/vm/parser.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/parser.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/compiler_stats.h"
@@ skipping 124 matching lines @@
 
   // Allocate parameters and local variables, either in the local frame or
   // in the context(s).
   LocalScope* context_owner = NULL;  // No context needed yet.
   int next_free_frame_index =
       scope->AllocateVariables(first_parameter_index_,
                                parameter_count,
                                first_stack_local_index_,
                                scope,
                                &context_owner);
+
+  // If this function is not a closure function and if it contains captured
+  // variables, the context needs to be saved on entry and restored on exit.
+  // Add and allocate a local variable to this purpose.
+  if ((context_owner != NULL) && !function().IsClosureFunction()) {
+    const String& context_var_name =
+        String::ZoneHandle(String::NewSymbol(":saved_entry_context_var"));
+    LocalVariable* context_var =
+        new LocalVariable(function().token_index(),
+                          context_var_name,
+                          Type::ZoneHandle(Type::DynamicType()));
+    context_var->set_index(next_free_frame_index--);
+    scope->AddVariable(context_var);
+    set_saved_context_var(context_var);
+  }
+
   // Frame indices are relative to the frame pointer and are decreasing.
   ASSERT(next_free_frame_index <= first_stack_local_index_);
   stack_local_count_ = first_stack_local_index_ - next_free_frame_index;
 }
 
 
 struct Parser::Block : public ZoneAllocated {
   Block(Block* outer_block, LocalScope* local_scope, SequenceNode* seq)
     : parent(outer_block), scope(local_scope), statements(seq) {
     ASSERT(scope != NULL);
@@ skipping 8070 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart