Support for global var shortcuts in script contexts.

src/contexts.cc

 // Copyright 2011 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.
 
 #include "src/v8.h"
 
 #include "src/bootstrapper.h"
 #include "src/debug.h"
 #include "src/scopeinfo.h"
 
@@ skipping 22 matching lines @@
 }
 
 
 bool ScriptContextTable::Lookup(Handle<ScriptContextTable> table,
                                 Handle<String> name, LookupResult* result) {
   for (int i = 0; i < table->used(); i++) {
     Handle<Context> context = GetContext(table, i);
     DCHECK(context->IsScriptContext());
     Handle<ScopeInfo> scope_info(ScopeInfo::cast(context->extension()));
     int slot_index = ScopeInfo::ContextSlotIndex(
-        scope_info, name, &result->mode, &result->init_flag,
+        scope_info, name, &result->mode, &result->location, &result->init_flag,
         &result->maybe_assigned_flag);
 
-    if (slot_index >= 0) {
+    if (slot_index >= 0 && result->location == VariableLocation::CONTEXT) {
       result->context_index = i;
       result->slot_index = slot_index;
       return true;
     }
   }
   return false;
 }
 
 
 Context* Context::declaration_context() {
@@ skipping 223 matching lines @@
       // for the context index.
       Handle<ScopeInfo> scope_info;
       if (context->IsFunctionContext()) {
         scope_info = Handle<ScopeInfo>(
             context->closure()->shared()->scope_info(), isolate);
       } else {
         scope_info = Handle<ScopeInfo>(
             ScopeInfo::cast(context->extension()), isolate);
       }
       VariableMode mode;
+      VariableLocation location;
       InitializationFlag init_flag;
       // TODO(sigurds) Figure out whether maybe_assigned_flag should
       // be used to compute binding_flags.
       MaybeAssignedFlag maybe_assigned_flag;
       int slot_index = ScopeInfo::ContextSlotIndex(
-          scope_info, name, &mode, &init_flag, &maybe_assigned_flag);
+          scope_info, name, &mode, &location, &init_flag, &maybe_assigned_flag);
       DCHECK(slot_index < 0 || slot_index >= MIN_CONTEXT_SLOTS);
-      if (slot_index >= 0) {
+      if (slot_index >= 0 && location == VariableLocation::CONTEXT) {
         if (FLAG_trace_contexts) {
           PrintF("=> found local in context slot %d (mode = %d)\n",
                  slot_index, mode);
         }
         *index = slot_index;
         GetAttributesAndBindingFlags(mode, init_flag, attributes,
                                      binding_flags);
         return context;
       }
 
@@ skipping 37 matching lines @@
     }
   } while (follow_context_chain);
 
   if (FLAG_trace_contexts) {
     PrintF("=> no property/slot found\n");
   }
   return Handle<Object>::null();
 }
 
 
+void Context::InitializeGlobalSlots() {
+  DCHECK(IsScriptContext());
+  DisallowHeapAllocation no_gc;
+
+  ScopeInfo* scope_info = ScopeInfo::cast(extension());
+
+  int context_globals = scope_info->ContextGlobalCount();
+  if (context_globals > 0) {
+    PropertyCell* empty_cell = GetHeap()->empty_property_cell();
+
+    int context_locals = scope_info->ContextLocalCount();
+    int index = Context::MIN_CONTEXT_SLOTS + context_locals;
+    for (int i = 0; i < context_globals; i++) {
+      // Clear both read and write slots.
+      set(index++, empty_cell);
+      set(index++, empty_cell);
+    }
+  }
+}
+
+
 void Context::AddOptimizedFunction(JSFunction* function) {
   DCHECK(IsNativeContext());
 #ifdef ENABLE_SLOW_DCHECKS
   if (FLAG_enable_slow_asserts) {
     Object* element = get(OPTIMIZED_FUNCTIONS_LIST);
     while (!element->IsUndefined()) {
       CHECK(element != function);
       element = JSFunction::cast(element)->next_function_link();
     }
   }
@@ skipping 124 matching lines @@
   // During bootstrapping we allow all objects to pass as global
   // objects. This is necessary to fix circular dependencies.
   return isolate->heap()->gc_state() != Heap::NOT_IN_GC ||
       isolate->bootstrapper()->IsActive() ||
       object->IsGlobalObject();
 }
 #endif
 
 }  // namespace internal
 }  // namespace v8