Align double array backing store during compaction and mark-sweep promotion.

src/mark-compact.cc

 // Copyright 2012 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 1996 matching lines @@
       Heap::UpdateAllocationSiteFeedback(object);
 
       offset++;
       current_cell >>= 1;
       // Aggressively promote young survivors to the old space.
       if (TryPromoteObject(object, size)) {
         continue;
       }
 
       // Promotion failed. Just migrate object to another semispace.
-      MaybeObject* allocation = new_space->AllocateRaw(size);
+      int allocation_size = size;
+      if (Heap::MustBeDoubleAligned(object))  {
+        ASSERT(kObjectAlignment != kDoubleAlignment);
+        allocation_size += kPointerSize;
+      }
+      MaybeObject* allocation = new_space->AllocateRaw(allocation_size);
       if (allocation->IsFailure()) {
         if (!new_space->AddFreshPage()) {
           // Shouldn't happen. We are sweeping linearly, and to-space
           // has the same number of pages as from-space, so there is
           // always room.
           UNREACHABLE();
         }
-        allocation = new_space->AllocateRaw(size);
+        allocation = new_space->AllocateRaw(allocation_size);
         ASSERT(!allocation->IsFailure());
       }
-      Object* target = allocation->ToObjectUnchecked();
-
-      MigrateObject(HeapObject::cast(target)->address(),
+      Object* result = allocation->ToObjectUnchecked();
+      HeapObject* target = HeapObject::cast(result);
+      if (Heap::MustBeDoubleAligned(object))  {
+        target = heap()->EnsureDoubleAligned(target, allocation_size);
+      }
+      MigrateObject(target->address(),
                     object->address(),
                     size,
                     NEW_SPACE);
     }
     *cells = 0;
   }
   return survivors_size;
 }
 
 
@@ skipping 897 matching lines @@
   if (map_word.IsForwardingAddress()) {
     return String::cast(map_word.ToForwardingAddress());
   }
 
   return String::cast(*p);
 }
 
 
 bool MarkCompactCollector::TryPromoteObject(HeapObject* object,
                                             int object_size) {
+  int allocation_size = object_size;
+  if (Heap::MustBeDoubleAligned(object))  {
+    ASSERT(kObjectAlignment != kDoubleAlignment);
+    allocation_size += kPointerSize;
+  }
+
   // TODO(hpayer): Replace that check with an assert.
-  CHECK(object_size <= Page::kMaxNonCodeHeapObjectSize);
+  CHECK(allocation_size <= Page::kNonCodeObjectAreaSize);
 
   OldSpace* target_space = heap()->TargetSpace(object);
 
   ASSERT(target_space == heap()->old_pointer_space() ||
          target_space == heap()->old_data_space());
   Object* result;
-  MaybeObject* maybe_result = target_space->AllocateRaw(object_size);
+  MaybeObject* maybe_result = target_space->AllocateRaw(allocation_size);
   if (maybe_result->ToObject(&result)) {
     HeapObject* target = HeapObject::cast(result);
+    if (Heap::MustBeDoubleAligned(object))  {
+      target = heap()->EnsureDoubleAligned(target, allocation_size);
+    }
     MigrateObject(target->address(),
                   object->address(),
                   object_size,
                   target_space->identity());
     heap()->mark_compact_collector()->tracer()->
         increment_promoted_objects_size(object_size);
     return true;
   }
 
   return false;
@@ skipping 50 matching lines @@
     if (*cell == 0) continue;
 
     int live_objects = MarkWordToObjectStarts(*cell, offsets);
     for (int i = 0; i < live_objects; i++) {
       Address object_addr = cell_base + offsets[i] * kPointerSize;
       HeapObject* object = HeapObject::FromAddress(object_addr);
       ASSERT(Marking::IsBlack(Marking::MarkBitFrom(object)));
 
       int size = object->Size();
 
-      MaybeObject* target = space->AllocateRaw(size);
+      int allocation_size = size;
+      if (Heap::MustBeDoubleAligned(object))  {
+        ASSERT(kObjectAlignment != kDoubleAlignment);
+        allocation_size += kPointerSize;
+      }
+      MaybeObject* target = space->AllocateRaw(allocation_size);
       if (target->IsFailure()) {
         // OS refused to give us memory.
         V8::FatalProcessOutOfMemory("Evacuation");
         return;
       }
 
-      Object* target_object = target->ToObjectUnchecked();
-
-      MigrateObject(HeapObject::cast(target_object)->address(),
+      Object* result = target->ToObjectUnchecked();
+      HeapObject* target_object = HeapObject::cast(result);
+      if (Heap::MustBeDoubleAligned(object)) {
+        target_object =
+            heap()->EnsureDoubleAligned(target_object, allocation_size);
+      }
+      MigrateObject(target_object->address(),
                     object_addr,
                     size,
                     space->identity());
       ASSERT(object->map_word().IsForwardingAddress());
     }
 
     // Clear marking bits for current cell.
     *cell = 0;
   }
   p->ResetLiveBytes();
@@ skipping 1312 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal