Fix heap verifier for partially constructed arrays when allocation folding is off.

src/objects-debug.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 312 matching lines @@
         int field = descriptors->GetFieldIndex(i);
         Object* value = RawFastPropertyAt(field);
         if (r.IsDouble()) ASSERT(value->IsHeapNumber());
         if (value->IsUninitialized()) continue;
         if (r.IsSmi()) ASSERT(value->IsSmi());
         if (r.IsHeapObject()) ASSERT(value->IsHeapObject());
       }
     }
   }
 
-  // TODO(hpayer): deal gracefully with partially constructed JSObjects, when
-  // allocation folding is turned off.
-  if (reinterpret_cast<Map*>(elements()) !=
-      GetHeap()->one_pointer_filler_map()) {
+  if ((!FLAG_use_gvn || !FLAG_use_allocation_folding) &&
+      (reinterpret_cast<Map*>(elements()) ==
+      GetHeap()->one_pointer_filler_map())) {
+    // A GC was caused while constructing this object. This can just happen when
+    // allocation folding is turned off. The elements pointer may point to a

[mvstanton, 2013/09/13 09:57:13]

cool but can you reverse the if, I don't really like "then" blocks that are
empty!

[Hannes Payer (out of office), 2013/09/13 11:30:27]

Done.

+    // filler map in that case.
+  } else {
     CHECK_EQ((map()->has_fast_smi_or_object_elements() ||
               (elements() == GetHeap()->empty_fixed_array())),
              (elements()->map() == GetHeap()->fixed_array_map() ||
               elements()->map() == GetHeap()->fixed_cow_array_map()));
     CHECK(map()->has_fast_object_elements() == HasFastObjectElements());
   }
 }
 
 
 void Map::MapVerify() {
@@ skipping 329 matching lines @@
             DependentCode::kWeaklyEmbeddedGroup, this));
       }
     }
   }
 }
 
 
 void JSArray::JSArrayVerify() {
   JSObjectVerify();
   CHECK(length()->IsNumber() || length()->IsUndefined());
-  // TODO(hpayer): deal gracefully with partially constructed JSObjects, when
-  // allocation folding is turned off.
-  if (reinterpret_cast<Map*>(elements()) !=
-      GetHeap()->one_pointer_filler_map()) {
+  if ((!FLAG_use_gvn || !FLAG_use_allocation_folding) &&
+      (reinterpret_cast<Map*>(elements()) ==
+      GetHeap()->one_pointer_filler_map())) {
+    // A GC was caused while constructing this array. This can just happen when
+    // allocation folding is turned off. The elements pointer may point to a

[mvstanton, 2013/09/13 09:57:13]

same thing.

[Hannes Payer (out of office), 2013/09/13 11:30:27]

Done.

+    // filler map in that case.
+  } else {
     CHECK(elements()->IsUndefined() ||
           elements()->IsFixedArray() ||
           elements()->IsFixedDoubleArray());
     // TODO(mvstanton): to diagnose chromium bug 284577, remove after.
     AllocationMemento* memento = AllocationMemento::FindForJSObject(this);
     if (memento != NULL && memento->IsValid()) {
       memento->AllocationMementoVerify();
     }
   }
 }
@@ skipping 487 matching lines @@
   for (int i = 0; i < number_of_transitions(); ++i) {
     if (!CheckOneBackPointer(current_map, GetTarget(i))) return false;
   }
   return true;
 }
 
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal