Revert r1971. Doesn't compile.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1972 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap-inl.h

@@ -191,27 +191,6 @@ void Heap::CopyBlock(Object** dst, Object** src, int byte_size) {
 }
 
 
-void Heap::ScavengeObject(HeapObject** p, HeapObject* object) {
-  ASSERT(InFromSpace(object));
-
-  // We use the first word (where the map pointer usually is) of a heap
-  // object to record the forwarding pointer.  A forwarding pointer can
-  // point to an old space, the code space, or the to space of the new
-  // generation.
-  MapWord first_word = object->map_word();
-
-  // If the first word is a forwarding address, the object has already been
-  // copied.
-  if (first_word.IsForwardingAddress()) {
-    *p = first_word.ToForwardingAddress();
-    return;
-  }
-
-  // Call the slow part of scavenge object.
-  return ScavengeObjectSlow(p, object);
-}
-
-
 Object* Heap::GetKeyedLookupCache() {
   if (keyed_lookup_cache()->IsUndefined()) {
     Object* obj = LookupCache::Allocate(4);

src/heap.cc

@@ -537,39 +537,8 @@ class ScavengeVisitor: public ObjectVisitor {
 };
 
 
-// A queue of pointers and maps of to-be-promoted objects during a
-// scavenge collection.
-class PromotionQueue {
- public:
-  void Initialize(Address start_address) {
-    front_ = rear_ = reinterpret_cast<HeapObject**>(start_address);
-  }
-
-  bool is_empty() { return front_ <= rear_; }
-
-  void insert(HeapObject* object, Map* map) {
-    *(--rear_) = object;
-    *(--rear_) = map;
-    // Assert no overflow into live objects.
-    ASSERT(rear_ >= Heap::new_space()->top());
-  }
-
-  void remove(HeapObject** object, Map** map) {
-    *object = *(--front_);
-    *map = Map::cast(*(--front_));
-    // Assert no underflow.
-    ASSERT(front_ >= rear_);
-  }
-
- private:
-  // The front of the queue is higher in memory than the rear.
-  HeapObject** front_;
-  HeapObject** rear_;
-};
-
-
 // Shared state read by the scavenge collector and set by ScavengeObject.
-static PromotionQueue promotion_queue;
+static Address promoted_rear = NULL;
 
 
 #ifdef DEBUG
@@ -655,7 +624,8 @@ void Heap::Scavenge() {
   // frees up its size in bytes from the top of the new space, and
   // objects are at least one pointer in size.
   Address new_space_front = new_space_.ToSpaceLow();
-  promotion_queue.Initialize(new_space_.ToSpaceHigh());
+  Address promoted_front = new_space_.ToSpaceHigh();
+  promoted_rear = new_space_.ToSpaceHigh();
 
   ScavengeVisitor scavenge_visitor;
   // Copy roots.
@@ -672,6 +642,7 @@ void Heap::Scavenge() {
 
   do {
     ASSERT(new_space_front <= new_space_.top());
+    ASSERT(promoted_front >= promoted_rear);
 
     // The addresses new_space_front and new_space_.top() define a
     // queue of unprocessed copied objects.  Process them until the
@@ -682,26 +653,15 @@ void Heap::Scavenge() {
       new_space_front += object->Size();
     }
 
-    // Promote and process all the to-be-promoted objects.
-    while (!promotion_queue.is_empty()) {
-      HeapObject* source;
-      Map* map;
-      promotion_queue.remove(&source, &map);
-      // Copy the from-space object to its new location (given by the
-      // forwarding address) and fix its map.
-      HeapObject* target = source->map_word().ToForwardingAddress();
-      CopyBlock(reinterpret_cast<Object**>(target->address()),
-                reinterpret_cast<Object**>(source->address()),
-                source->SizeFromMap(map));
-      target->set_map(map);
-
-#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
-      // Update NewSpace stats if necessary.
-      RecordCopiedObject(target);
-#endif
-      // Visit the newly copied object for pointers to new space.
-      target->Iterate(&scavenge_visitor);
-      UpdateRSet(target);
+    // The addresses promoted_front and promoted_rear define a queue
+    // of unprocessed addresses of promoted objects.  Process them
+    // until the queue is empty.
+    while (promoted_front > promoted_rear) {
+      promoted_front -= kPointerSize;
+      HeapObject* object =
+          HeapObject::cast(Memory::Object_at(promoted_front));
+      object->Iterate(&scavenge_visitor);
+      UpdateRSet(object);
     }
 
     // Take another spin if there are now unswept objects in new space
@@ -858,8 +818,8 @@ HeapObject* Heap::MigrateObject(HeapObject* source,
   // Set the forwarding address.
   source->set_map_word(MapWord::FromForwardingAddress(target));
 
-#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
   // Update NewSpace stats if necessary.
+#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
   RecordCopiedObject(target);
 #endif
 
@@ -867,6 +827,28 @@ HeapObject* Heap::MigrateObject(HeapObject* source,
 }
 
 
+// Inlined function.
+void Heap::ScavengeObject(HeapObject** p, HeapObject* object) {
+  ASSERT(InFromSpace(object));
+
+  // We use the first word (where the map pointer usually is) of a heap
+  // object to record the forwarding pointer.  A forwarding pointer can
+  // point to an old space, the code space, or the to space of the new
+  // generation.
+  MapWord first_word = object->map_word();
+
+  // If the first word is a forwarding address, the object has already been
+  // copied.
+  if (first_word.IsForwardingAddress()) {
+    *p = first_word.ToForwardingAddress();
+    return;
+  }
+
+  // Call the slow part of scavenge object.
+  return ScavengeObjectSlow(p, object);
+}
+
+
 static inline bool IsShortcutCandidate(HeapObject* object, Map* map) {
   STATIC_ASSERT(kNotStringTag != 0 && kSymbolTag != 0);
   ASSERT(object->map() == map);
@@ -897,11 +879,6 @@ void Heap::ScavengeObjectSlow(HeapObject** p, HeapObject* object) {
   }
 
   int object_size = object->SizeFromMap(first_word.ToMap());
-  // We rely on live objects in new space to be at least two pointers,
-  // so we can store the from-space address and map pointer of promoted
-  // objects in the to space.
-  ASSERT(object_size >= 2 * kPointerSize);
-
   // If the object should be promoted, we try to copy it to old space.
   if (ShouldBePromoted(object->address(), object_size)) {
     OldSpace* target_space = Heap::TargetSpace(object);
@@ -909,29 +886,16 @@ void Heap::ScavengeObjectSlow(HeapObject** p, HeapObject* object) {
            target_space == Heap::old_data_space_);
     Object* result = target_space->AllocateRaw(object_size);
     if (!result->IsFailure()) {
-      HeapObject* target = HeapObject::cast(result);
+      *p = MigrateObject(object, HeapObject::cast(result), object_size);
       if (target_space == Heap::old_pointer_space_) {
-        // Save the from-space object pointer and its map pointer at the
-        // top of the to space to be swept and copied later.  Write the
-        // forwarding address over the map word of the from-space
-        // object.
-        promotion_queue.insert(object, first_word.ToMap());
-        object->set_map_word(MapWord::FromForwardingAddress(target));
-
-        // Give the space allocated for the result a proper map by
-        // treating it as a free list node (not linked into the free
-        // list).
-        FreeListNode* node = FreeListNode::FromAddress(target->address());
-        node->set_size(object_size);
-
-        *p = target;
+        // Record the object's address at the top of the to space, to allow
+        // it to be swept by the scavenger.
+        promoted_rear -= kPointerSize;
+        Memory::Object_at(promoted_rear) = *p;
       } else {
-        // Objects promoted to the data space can be copied immediately
-        // and not revisited---we will never sweep that space for
-        // pointers and the copied objects do not contain pointers to
-        // new space objects.
-        *p = MigrateObject(object, target, object_size);
 #ifdef DEBUG
+        // Objects promoted to the data space should not have pointers to
+        // new space.
         VerifyNonPointerSpacePointersVisitor v;
         (*p)->Iterate(&v);
 #endif