Turn the unresolved-references list into a linked list using the VariableProxies themselves

src/ast/scopes.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_AST_SCOPES_H_
 #define V8_AST_SCOPES_H_
 
 #include "src/ast/ast.h"
 #include "src/base/hashmap.h"
 #include "src/globals.h"
@@ skipping 165 matching lines @@
                                const AstRawString* name,
                                Variable::Kind kind = Variable::NORMAL,
                                int start_position = kNoSourcePosition,
                                int end_position = kNoSourcePosition) {
     // Note that we must not share the unresolved variables with
     // the same name because they may be removed selectively via
     // RemoveUnresolved().
     DCHECK(!already_resolved());
     VariableProxy* proxy =
         factory->NewVariableProxy(name, kind, start_position, end_position);
-    unresolved_.Add(proxy, zone_);
+    proxy->set_next_unresolved(unresolved_);
+    unresolved_ = proxy;
     return proxy;
   }
 
   void AddUnresolved(VariableProxy* proxy) {
     DCHECK(!already_resolved());
     DCHECK(!proxy->is_resolved());
-    unresolved_.Add(proxy, zone_);
+    proxy->set_next_unresolved(unresolved_);
+    unresolved_ = proxy;
   }
 
   // Remove a unresolved variable. During parsing, an unresolved variable
   // may have been added optimistically, but then only the variable name
   // was used (typically for labels). If the variable was not declared, the
   // addition introduced a new unresolved variable which may end up being
   // allocated globally as a "ghost" variable. RemoveUnresolved removes
   // such a variable again if it was added; otherwise this is a no-op.
   bool RemoveUnresolved(VariableProxy* var);
 
@@ skipping 418 matching lines @@
   // an inner scope) with no intervening with statements or eval calls.
   VariableMap variables_;
   // Compiler-allocated (user-invisible) temporaries. Due to the implementation
   // of RemoveTemporary(), may contain nulls, which must be skipped-over during
   // allocation and printing.
   ZoneList<Variable*> temps_;
   // Parameter list in source order.
   ZoneList<Variable*> params_;
   // Variables that must be looked up dynamically.
   DynamicScopePart* dynamics_;
-  // Unresolved variables referred to from this scope.
-  ZoneList<VariableProxy*> unresolved_;
+  // Unresolved variables referred to from this scope. The proxies themselves
+  // form a linked list of all unresolved proxies.
+  VariableProxy* unresolved_;
   // Declarations.
   ZoneList<Declaration*> decls_;
   // Convenience variable.
   Variable* receiver_;
   // Function variable, if any; function scopes only.
   VariableDeclaration* function_;
   // new.target variable, function scopes only.
   Variable* new_target_;
   // Convenience variable; function scopes only.
   Variable* arguments_;
@@ skipping 184 matching lines @@
   AstValueFactory* ast_value_factory_;
   Zone* zone_;
 
   PendingCompilationErrorHandler pending_error_handler_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_SCOPES_H_