Allocate arguments object on-demand instead of at function entry....

src/scopes.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 63 matching lines @@
 LocalsMap::LocalsMap(bool gotta_love_static_overloading) : HashMap()  {}
 
 LocalsMap::LocalsMap() : HashMap(Match, &LocalsMapAllocator, 8)  {}
 LocalsMap::~LocalsMap()  {}
 
 
 Variable* LocalsMap::Declare(Scope* scope,
                              Handle<String> name,
                              Variable::Mode mode,
                              bool is_valid_LHS,
-                             bool is_this) {
+                             Variable::Kind kind) {
   HashMap::Entry* p = HashMap::Lookup(name.location(), name->Hash(), true);
   if (p->value == NULL) {
     // The variable has not been declared yet -> insert it.
     ASSERT(p->key == name.location());
-    p->value = new Variable(scope, name, mode, is_valid_LHS, is_this);
+    p->value = new Variable(scope, name, mode, is_valid_LHS, kind);
   }
   return reinterpret_cast<Variable*>(p->value);
 }
 
 
 Variable* LocalsMap::Lookup(Handle<String> name) {
   HashMap::Entry* p = HashMap::Lookup(name.location(), name->Hash(), false);
   if (p != NULL) {
     ASSERT(*reinterpret_cast<String**>(p->key) == *name);
     ASSERT(p->value != NULL);
@@ skipping 62 matching lines @@
 
   // Declare convenience variables.
   // Declare and allocate receiver (even for the global scope, and even
   // if naccesses_ == 0).
   // NOTE: When loading parameters in the global scope, we must take
   // care not to access them as properties of the global object, but
   // instead load them directly from the stack. Currently, the only
   // such parameter is 'this' which is passed on the stack when
   // invoking scripts
   { Variable* var =
-      locals_.Declare(this, Factory::this_symbol(), Variable::VAR, false, true);
+        locals_.Declare(this, Factory::this_symbol(), Variable::VAR,
+                        false, Variable::THIS);
     var->rewrite_ = new Slot(var, Slot::PARAMETER, -1);
     receiver_ = new VariableProxy(Factory::this_symbol(), true, false);
     receiver_->BindTo(var);
   }
 
   if (is_function_scope()) {
     // Declare 'arguments' variable which exists in all functions.
     // Note that it may never be accessed, in which case it won't
     // be allocated during variable allocation.
-    Declare(Factory::arguments_symbol(), Variable::VAR);
+    locals_.Declare(this, Factory::arguments_symbol(), Variable::VAR,
+                    true, Variable::ARGUMENTS);
   }
 }
 
 
 
 Variable* Scope::LookupLocal(Handle<String> name) {
   return locals_.Lookup(name);
 }
 
 
 Variable* Scope::Lookup(Handle<String> name) {
   for (Scope* scope = this;
        scope != NULL;
        scope = scope->outer_scope()) {
     Variable* var = scope->LookupLocal(name);
     if (var != NULL) return var;
   }
   return NULL;
 }
 
 
 Variable* Scope::DeclareFunctionVar(Handle<String> name) {
   ASSERT(is_function_scope() && function_ == NULL);
-  function_ = new Variable(this, name, Variable::CONST, true, false);
+  function_ = new Variable(this, name, Variable::CONST, true, Variable::NORMAL);
   return function_;
 }
 
 
 Variable* Scope::Declare(Handle<String> name, Variable::Mode mode) {
   // DYNAMIC variables are introduces during variable allocation,
   // INTERNAL variables are allocated explicitly, and TEMPORARY
   // variables are allocated via NewTemporary().
   ASSERT(mode == Variable::VAR || mode == Variable::CONST);
-  return locals_.Declare(this, name, mode, true, false);
+  return locals_.Declare(this, name, mode, true, Variable::NORMAL);
 }
 
 
 void Scope::AddParameter(Variable* var) {
   ASSERT(is_function_scope());
   ASSERT(LookupLocal(var->name()) == var);
   params_.Add(var);
 }
 
 
@@ skipping 13 matching lines @@
   for (int i = unresolved_.length(); i-- > 0;) {
     if (unresolved_[i] == var) {
       unresolved_.Remove(i);
       return;
     }
   }
 }
 
 
 VariableProxy* Scope::NewTemporary(Handle<String> name) {
-  Variable* var = new Variable(this, name, Variable::TEMPORARY, true, false);
+  Variable* var = new Variable(this, name, Variable::TEMPORARY, true,
+                               Variable::NORMAL);
   VariableProxy* tmp = new VariableProxy(name, false, false);
   tmp->BindTo(var);
   temps_.Add(var);
   return tmp;
 }
 
 
 void Scope::AddDeclaration(Declaration* declaration) {
   decls_.Add(declaration);
 }
@@ skipping 235 matching lines @@
 }
 #endif  // DEBUG
 
 
 Variable* Scope::NonLocal(Handle<String> name, Variable::Mode mode) {
   if (dynamics_ == NULL) dynamics_ = new DynamicScopePart();
   LocalsMap* map = dynamics_->GetMap(mode);
   Variable* var = map->Lookup(name);
   if (var == NULL) {
     // Declare a new non-local.
-    var = map->Declare(NULL, name, mode, true, false);
+    var = map->Declare(NULL, name, mode, true, Variable::NORMAL);
     // Allocate it by giving it a dynamic lookup.
     var->rewrite_ = new Slot(var, Slot::LOOKUP, -1);
   }
   return var;
 }
 
 
 // Lookup a variable starting with this scope. The result is either
 // the statically resolved (local!) variable belonging to an outer scope,
 // or NULL. It may be NULL because a) we couldn't find a variable, or b)
@@ skipping 95 matching lines @@
       // that the variable might be introduced dynamically (through
       // a local or outer eval() call, or an outer 'with' statement),
       // or we don't know about the outer scope (because we are
       // in an eval scope).
       if (is_global_scope() ||
           !(scope_inside_with_ || outer_scope_is_eval_scope_ ||
             scope_calls_eval_ || outer_scope_calls_eval_)) {
         // We must have a global variable.
         ASSERT(global_scope != NULL);
         var = new Variable(global_scope, proxy->name(),
-                           Variable::DYNAMIC, true, false);
+                           Variable::DYNAMIC, true, Variable::NORMAL);
 
       } else if (scope_inside_with_) {
         // If we are inside a with statement we give up and look up
         // the variable at runtime.
         var = NonLocal(proxy->name(), Variable::DYNAMIC);
 
       } else if (invalidated_local != NULL) {
         // No with statements are involved and we found a local
         // variable that might be shadowed by eval introduced
         // variables.
@@ skipping 157 matching lines @@
     // and bind the corresponding proxy. It's ok to declare it only now
     // because it's a local variable that is allocated after the parameters
     // have been allocated.
     //
     // Note: This is "almost" at temporary variable but we cannot use
     // NewTemporary() because the mode needs to be INTERNAL since this
     // variable may be allocated in the heap-allocated context (temporaries
     // are never allocated in the context).
     Variable* arguments_shadow =
         new Variable(this, Factory::arguments_shadow_symbol(),
-                     Variable::INTERNAL, true, false);
+                     Variable::INTERNAL, true, Variable::ARGUMENTS);
     arguments_shadow_ =
         new VariableProxy(Factory::arguments_shadow_symbol(), false, false);
     arguments_shadow_->BindTo(arguments_shadow);
     temps_.Add(arguments_shadow);
 
     // Allocate the parameters by rewriting them into '.arguments[i]' accesses.
     for (int i = 0; i < params_.length(); i++) {
       Variable* var = params_[i];
       ASSERT(var->scope() == this);
       if (MustAllocate(var)) {
@@ skipping 121 matching lines @@
   if (num_heap_slots_ == Context::MIN_CONTEXT_SLOTS &&
       !must_have_local_context) {
     num_heap_slots_ = 0;
   }
 
   // Allocation done.
   ASSERT(num_heap_slots_ == 0 || num_heap_slots_ >= Context::MIN_CONTEXT_SLOTS);
 }
 
 } }  // namespace v8::internal