A collection of context-related refactoring changes.

src/contexts.cc

 // Copyright 2011 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 78 matching lines @@
     PrintF(")\n");
   }
 
   do {
     if (FLAG_trace_contexts) {
       PrintF(" - looking in context %p", reinterpret_cast<void*>(*context));
       if (context->IsGlobalContext()) PrintF(" (global context)");
       PrintF("\n");
     }
 
-    // check extension/with object
+    // Check extension/with/global object.
     if (context->has_extension()) {
       Handle<JSObject> extension = Handle<JSObject>(context->extension(),
                                                     isolate);
       // Context extension objects needs to behave as if they have no
       // prototype.  So even if we want to follow prototype chains, we
       // need to only do a local lookup for context extension objects.
       if ((flags & FOLLOW_PROTOTYPE_CHAIN) == 0 ||
           extension->IsJSContextExtensionObject()) {
         *attributes = extension->GetLocalPropertyAttribute(*name);
       } else {
         *attributes = extension->GetPropertyAttribute(*name);
       }
       if (*attributes != ABSENT) {
         // property found
         if (FLAG_trace_contexts) {
           PrintF("=> found property in context object %p\n",
                  reinterpret_cast<void*>(*extension));
         }
         return extension;
       }
     }
 
-    if (context->is_function_context()) {

[Kevin Millikin (Chromium), 2011/06/08 16:35:52]

Global contexts used to satisfy this predicate, but they have the empty function
as closure, so there were never any locals, parameters, or a function name. 
It's safe to skip this for global contexts.

[Mads Ager (chromium), 2011/06/09 07:31:00]

Could you add a comment to that effect before the conditional?

+    if (context->IsFunctionContext()) {
       // we have context-local slots
 
       // check non-parameter locals in context
       Handle<SerializedScopeInfo> scope_info(
           context->closure()->shared()->scope_info(), isolate);
       Variable::Mode mode;
       int index = scope_info->ContextSlotIndex(*name, &mode);
       ASSERT(index < 0 || index >= MIN_CONTEXT_SLOTS);
       if (index >= 0) {
         // slot found
@@ skipping 49 matching lines @@
           *index_ = index;
           *attributes = READ_ONLY;
           return context;
         }
       }
     }
 
     // proceed with enclosing context
     if (context->IsGlobalContext()) {
       follow_context_chain = false;
-    } else if (context->is_function_context()) {

[Kevin Millikin (Chromium), 2011/06/08 16:35:52]

Global contexts couldn't reach this site.

-      context = Handle<Context>(Context::cast(context->closure()->context()),
-                                isolate);
+    } else if (context->IsFunctionContext()) {
+      context = Handle<Context>(context->closure()->context(), isolate);
     } else {
       context = Handle<Context>(context->previous(), isolate);
     }
   } while (follow_context_chain);
 
   // slot not found
   if (FLAG_trace_contexts) {
     PrintF("=> no property/slot found\n");
   }
   return Handle<Object>::null();
 }
 
 
 bool Context::GlobalIfNotShadowedByEval(Handle<String> name) {
   Context* context = this;
 
   // Check that there is no local with the given name in contexts
   // before the global context and check that there are no context
   // extension objects (conservative check for with statements).
   while (!context->IsGlobalContext()) {
-    // Check if the context is a potentially a with context.
+    // Check if the context is a catch or with context, or has called
+    // non-strict eval.
     if (context->has_extension()) return false;
 
     // Not a with context so it must be a function context.
-    ASSERT(context->is_function_context());

[Kevin Millikin (Chromium), 2011/06/08 16:35:52]

Global contexts couldn't reach this site.

+    ASSERT(context->IsFunctionContext());
 
     // Check non-parameter locals.
     Handle<SerializedScopeInfo> scope_info(
         context->closure()->shared()->scope_info());
     Variable::Mode mode;
     int index = scope_info->ContextSlotIndex(*name, &mode);
     ASSERT(index < 0 || index >= MIN_CONTEXT_SLOTS);
     if (index >= 0) return false;
 
     // Check parameter locals.
@@ skipping 108 matching lines @@
   // During bootstrapping we allow all objects to pass as global
   // objects. This is necessary to fix circular dependencies.
   Isolate* isolate = Isolate::Current();
   return isolate->heap()->gc_state() != Heap::NOT_IN_GC ||
       isolate->bootstrapper()->IsActive() ||
       object->IsGlobalObject();
 }
 #endif
 
 } }  // namespace v8::internal