Change the representation of catch contexts.

src/contexts.h

 // 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 163 matching lines @@
     ASSERT(context->IsContext());
     return reinterpret_cast<Context*>(context);
   }
 
   // The default context slot layout; indices are FixedArray slot indices.
   enum {
     // These slots are in all contexts.
     CLOSURE_INDEX,
     FCONTEXT_INDEX,
     PREVIOUS_INDEX,
+    // The extension slot is used for either the global object (in global
+    // contexts), eval extension object (function contexts), subject of with
+    // (with contexts), or the variable name (catch contexts).
     EXTENSION_INDEX,
     GLOBAL_INDEX,
     MIN_CONTEXT_SLOTS,
 
+    // This slot holds the thrown value in catch contexts.
+    THROWN_OBJECT_INDEX = MIN_CONTEXT_SLOTS,
+
     // These slots are only in global contexts.
     GLOBAL_PROXY_INDEX = MIN_CONTEXT_SLOTS,
     SECURITY_TOKEN_INDEX,
     ARGUMENTS_BOILERPLATE_INDEX,
     STRICT_MODE_ARGUMENTS_BOILERPLATE_INDEX,
     JS_ARRAY_MAP_INDEX,
     REGEXP_RESULT_MAP_INDEX,
     FUNCTION_MAP_INDEX,
     STRICT_MODE_FUNCTION_MAP_INDEX,
     FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX,
@@ skipping 60 matching lines @@
   Context* fcontext() { return Context::cast(get(FCONTEXT_INDEX)); }
   void set_fcontext(Context* context) { set(FCONTEXT_INDEX, context); }
 
   Context* previous() {
     Object* result = unchecked_previous();
     ASSERT(IsBootstrappingOrContext(result));
     return reinterpret_cast<Context*>(result);
   }
   void set_previous(Context* context) { set(PREVIOUS_INDEX, context); }
 
-  bool has_extension() { return unchecked_extension() != NULL; }
-  JSObject* extension() { return JSObject::cast(unchecked_extension()); }
-  void set_extension(JSObject* object) { set(EXTENSION_INDEX, object); }
+  bool has_extension() { return extension() != NULL; }
+  Object* extension() { return get(EXTENSION_INDEX); }
+  void set_extension(Object* object) { set(EXTENSION_INDEX, object); }
 
   GlobalObject* global() {
     Object* result = get(GLOBAL_INDEX);
     ASSERT(IsBootstrappingOrGlobalObject(result));
     return reinterpret_cast<GlobalObject*>(result);
   }
   void set_global(GlobalObject* global) { set(GLOBAL_INDEX, global); }
 
   // Returns a JSGlobalProxy object or null.
   JSObject* global_proxy();
@@ skipping 97 matching lines @@
       kHeaderSize, kSize, kSize> ScavengeBodyDescriptor;
 
   typedef FixedBodyDescriptor<
       kHeaderSize,
       kHeaderSize + FIRST_WEAK_SLOT * kPointerSize,
       kSize> MarkCompactBodyDescriptor;
 
  private:
   // Unchecked access to the slots.
   Object* unchecked_previous() { return get(PREVIOUS_INDEX); }
-  Object* unchecked_extension() { return get(EXTENSION_INDEX); }
 
 #ifdef DEBUG
   // Bootstrapping-aware type checks.
   static bool IsBootstrappingOrContext(Object* object);
   static bool IsBootstrappingOrGlobalObject(Object* object);
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_CONTEXTS_H_