Always sweep precisely.

src/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/once.h"
 #include "src/base/utils/random-number-generator.h"
@@ skipping 4190 matching lines @@
   Struct* result;
   { AllocationResult allocation = Allocate(map, space);
     if (!allocation.To(&result)) return allocation;
   }
   result->InitializeBody(size);
   return result;
 }
 
 
 bool Heap::IsHeapIterable() {
+  // TODO(hpayer): This function is not correct. Allocation folding in old
+  // space breaks the iterability.
   return (old_pointer_space()->swept_precisely() &&
           old_data_space()->swept_precisely() &&
           new_space_top_after_last_gc_ == new_space()->top());
 }
 
 
 void Heap::MakeHeapIterable() {
   ASSERT(AllowHeapAllocation::IsAllowed());
   if (!IsHeapIterable()) {
     CollectAllGarbage(kMakeHeapIterableMask, "Heap::MakeHeapIterable");
   }
+  if (mark_compact_collector()->sweeping_in_progress()) {
+    mark_compact_collector()->EnsureSweepingCompleted();
+  }
   ASSERT(IsHeapIterable());
 }
 
 
 void Heap::AdvanceIdleIncrementalMarking(intptr_t step_size) {
   HistogramTimerScope idle_notification_scope(
       isolate_->counters()->gc_incremental_marking());
 
   incremental_marking()->Step(step_size,
                               IncrementalMarking::NO_GC_VIA_STACK_GUARD);
@@ skipping 2213 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal