Reduce the number of captured variables in async code, by only capturing local

runtime/vm/ast.h

 // 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.
 
 #ifndef VM_AST_H_
 #define VM_AST_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/growable_array.h"
@@ skipping 147 matching lines @@
 };
 
 
 class AwaitNode : public AstNode {
  public:
   AwaitNode(intptr_t token_pos,
             AstNode* expr,
             LocalVariable* saved_try_ctx,
             LocalVariable* async_saved_try_ctx,
             LocalVariable* outer_saved_try_ctx,
-            LocalVariable* outer_async_saved_try_ctx)
+            LocalVariable* outer_async_saved_try_ctx,
+            LocalScope* scope)
     : AstNode(token_pos),
       expr_(expr),
       saved_try_ctx_(saved_try_ctx),
       async_saved_try_ctx_(async_saved_try_ctx),
       outer_saved_try_ctx_(outer_saved_try_ctx),
-      outer_async_saved_try_ctx_(outer_async_saved_try_ctx) { }
+      outer_async_saved_try_ctx_(outer_async_saved_try_ctx),
+      scope_(scope) { }
 
   void VisitChildren(AstNodeVisitor* visitor) const {
     expr_->Visit(visitor);
   }
 
   AstNode* expr() const { return expr_; }
   LocalVariable* saved_try_ctx() const { return saved_try_ctx_; }
   LocalVariable* async_saved_try_ctx() const { return async_saved_try_ctx_; }
   LocalVariable* outer_saved_try_ctx() const { return outer_saved_try_ctx_; }
   LocalVariable* outer_async_saved_try_ctx() const {
     return outer_async_saved_try_ctx_;
   }
+  LocalScope* scope() const { return scope_; }
 
   DECLARE_COMMON_NODE_FUNCTIONS(AwaitNode);
 
  private:
   AstNode* expr_;
   LocalVariable* saved_try_ctx_;
   LocalVariable* async_saved_try_ctx_;
   LocalVariable* outer_saved_try_ctx_;
   LocalVariable* outer_async_saved_try_ctx_;
+  LocalScope* scope_;
 
   DISALLOW_COPY_AND_ASSIGN(AwaitNode);
 };
 
 
 // AwaitMarker nodes are used to generate markers that the FlowGraphBuilder
 // relies on. A marker indicates that a new await state needs to be
 // added to a function preamble. This type also triggers storing of the
 // current context.
 //
 // It is expected (ASSERT) that an AwaitMarker is followed by
 // a return node of kind kContinuationTarget. That is:
 //   <AwaitMarker> -> <other nodes> -> <kContinuationTarget> -> <other nodes> ->
 //   <AwaitMarker> -> ...
 class AwaitMarkerNode : public AstNode {
  public:
-  AwaitMarkerNode() : AstNode(Scanner::kNoSourcePos) { }
+  AwaitMarkerNode(LocalScope* async_scope, LocalScope* await_scope)
+    : AstNode(Scanner::kNoSourcePos),
+      async_scope_(async_scope),
+      await_scope_(await_scope) {
+    ASSERT(async_scope != NULL);
+    ASSERT(await_scope != NULL);
+    await_scope->CaptureLocalVariables(async_scope);
+  }
 
   void VisitChildren(AstNodeVisitor* visitor) const { }
 
-  LocalScope* scope() const { return scope_; }
-  void set_scope(LocalScope* scope) { scope_ = scope; }
+  LocalScope* async_scope() const { return async_scope_; }
+  LocalScope* await_scope() const { return await_scope_; }
 
   DECLARE_COMMON_NODE_FUNCTIONS(AwaitMarkerNode);
 
  private:
-  LocalScope* scope_;
+  LocalScope* async_scope_;
+  LocalScope* await_scope_;
 
   DISALLOW_COPY_AND_ASSIGN(AwaitMarkerNode);
 };
 
 
 class SequenceNode : public AstNode {
  public:
   SequenceNode(intptr_t token_pos, LocalScope* scope)
     : AstNode(token_pos),
       scope_(scope),
@@ skipping 1783 matching lines @@
   const intptr_t try_index_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(InlinedFinallyNode);
 };
 
 }  // namespace dart
 
 #undef DECLARE_COMMON_NODE_FUNCTIONS
 
 #endif  // VM_AST_H_