Make Failure inherit from MaybeObject instead of Object.

src/mark-compact.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 1246 matching lines @@
       Memory::Address_at(free_start + offset) = kZapValue;
     }
   }
 #endif
 }
 
 
 // Try to promote all objects in new space.  Heap numbers and sequential
 // strings are promoted to the code space, large objects to large object space,
 // and all others to the old space.
-inline Object* MCAllocateFromNewSpace(HeapObject* object, int object_size) {
-  Object* forwarded;
+inline MaybeObject* MCAllocateFromNewSpace(HeapObject* object,
+                                           int object_size) {
+  MaybeObject* forwarded;
   if (object_size > Heap::MaxObjectSizeInPagedSpace()) {
     forwarded = Failure::Exception();
   } else {
     OldSpace* target_space = Heap::TargetSpace(object);
     ASSERT(target_space == Heap::old_pointer_space() ||
            target_space == Heap::old_data_space());
     forwarded = target_space->MCAllocateRaw(object_size);
   }
-  if (forwarded->IsFailure()) {
-    forwarded = Heap::new_space()->MCAllocateRaw(object_size);
+  Object* result;
+  if (!forwarded->ToObject(&result)) {
+    result = Heap::new_space()->MCAllocateRaw(object_size)->ToObjectUnchecked();
   }
-  return forwarded;
+  return result;
 }
 
 
 // Allocation functions for the paged spaces call the space's MCAllocateRaw.
-inline Object* MCAllocateFromOldPointerSpace(HeapObject* ignore,
-                                             int object_size) {
+MUST_USE_RESULT inline MaybeObject* MCAllocateFromOldPointerSpace(
+    HeapObject* ignore,
+    int object_size) {
   return Heap::old_pointer_space()->MCAllocateRaw(object_size);
 }
 
 
-inline Object* MCAllocateFromOldDataSpace(HeapObject* ignore, int object_size) {
+MUST_USE_RESULT inline MaybeObject* MCAllocateFromOldDataSpace(
+    HeapObject* ignore,
+    int object_size) {
   return Heap::old_data_space()->MCAllocateRaw(object_size);
 }
 
 
-inline Object* MCAllocateFromCodeSpace(HeapObject* ignore, int object_size) {
+MUST_USE_RESULT inline MaybeObject* MCAllocateFromCodeSpace(
+    HeapObject* ignore,
+    int object_size) {
   return Heap::code_space()->MCAllocateRaw(object_size);
 }
 
 
-inline Object* MCAllocateFromMapSpace(HeapObject* ignore, int object_size) {
+MUST_USE_RESULT inline MaybeObject* MCAllocateFromMapSpace(
+    HeapObject* ignore,
+    int object_size) {
   return Heap::map_space()->MCAllocateRaw(object_size);
 }
 
 
-inline Object* MCAllocateFromCellSpace(HeapObject* ignore, int object_size) {
+MUST_USE_RESULT inline MaybeObject* MCAllocateFromCellSpace(
+    HeapObject* ignore, int object_size) {
   return Heap::cell_space()->MCAllocateRaw(object_size);
 }
 
 
 // The forwarding address is encoded at the same offset as the current
 // to-space object, but in from space.
 inline void EncodeForwardingAddressInNewSpace(HeapObject* old_object,
                                               int object_size,
                                               Object* new_object,
                                               int* ignored) {
@@ skipping 56 matching lines @@
   bool is_prev_alive = true;
 
   int object_size;  // Will be set on each iteration of the loop.
   for (Address current = start; current < end; current += object_size) {
     HeapObject* object = HeapObject::FromAddress(current);
     if (object->IsMarked()) {
       object->ClearMark();
       MarkCompactCollector::tracer()->decrement_marked_count();
       object_size = object->Size();
 
-      Object* forwarded = Alloc(object, object_size);
       // Allocation cannot fail, because we are compacting the space.
-      ASSERT(!forwarded->IsFailure());
+      Object* forwarded = Alloc(object, object_size)->ToObjectUnchecked();
       Encode(object, object_size, forwarded, offset);
 
 #ifdef DEBUG
       if (FLAG_gc_verbose) {
         PrintF("forward %p -> %p.\n", object->address(),
                HeapObject::cast(forwarded)->address());
       }
 #endif
       if (!is_prev_alive) {  // Transition from non-live to live.
         EncodeFreeRegion(free_start, static_cast<int>(current - free_start));
@@ skipping 148 matching lines @@
   Address old_addr = HeapObject::cast(*p)->address();
   Address new_addr = Memory::Address_at(old_addr);
   return String::cast(HeapObject::FromAddress(new_addr));
 }
 
 
 static bool TryPromoteObject(HeapObject* object, int object_size) {
   Object* result;
 
   if (object_size > Heap::MaxObjectSizeInPagedSpace()) {
-    result = Heap::lo_space()->AllocateRawFixedArray(object_size);
-    if (!result->IsFailure()) {
+    MaybeObject* maybe_result =
+        Heap::lo_space()->AllocateRawFixedArray(object_size);
+    if (maybe_result->ToObject(&result)) {
       HeapObject* target = HeapObject::cast(result);
       MigrateObject(target->address(), object->address(), object_size, true);
       MarkCompactCollector::tracer()->
           increment_promoted_objects_size(object_size);
       return true;
     }
   } else {
     OldSpace* target_space = Heap::TargetSpace(object);
 
     ASSERT(target_space == Heap::old_pointer_space() ||
            target_space == Heap::old_data_space());
-    result = target_space->AllocateRaw(object_size);
-    if (!result->IsFailure()) {
+    MaybeObject* maybe_result = target_space->AllocateRaw(object_size);
+    if (maybe_result->ToObject(&result)) {
       HeapObject* target = HeapObject::cast(result);
       MigrateObject(target->address(),
                     object->address(),
                     object_size,
                     target_space == Heap::old_pointer_space());
       MarkCompactCollector::tracer()->
           increment_promoted_objects_size(object_size);
       return true;
     }
   }
@@ skipping 27 matching lines @@
 
       size = object->Size();
       survivors_size += size;
 
       // Aggressively promote young survivors to the old space.
       if (TryPromoteObject(object, size)) {
         continue;
       }
 
       // Promotion failed. Just migrate object to another semispace.
-      Object* target = space->AllocateRaw(size);
-
       // Allocation cannot fail at this point: semispaces are of equal size.
-      ASSERT(!target->IsFailure());
+      Object* target = space->AllocateRaw(size)->ToObjectUnchecked();
 
       MigrateObject(HeapObject::cast(target)->address(),
                     current,
                     size,
                     false);
     } else {
       size = object->Size();
       Memory::Address_at(current) = NULL;
     }
   }
@@ skipping 1035 matching lines @@
 }
 
 
 void MarkCompactCollector::Initialize() {
   StaticPointersToNewGenUpdatingVisitor::Initialize();
   StaticMarkingVisitor::Initialize();
 }
 
 
 } }  // namespace v8::internal