Merged r15868, r15871, r15880, r15884 into trunk branch.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index bfeeae9efc04531b39c0577fbc23d8b3cf07e81c..a3834980b6baf155e421aa3ac7a2c10389e1b247 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -2724,21 +2724,11 @@ void MarkCompactCollector::MigrateObject(Address dst,
   HEAP_PROFILE(heap(), ObjectMoveEvent(src, dst));
   // TODO(hpayer): Replace that check with an assert.
   CHECK(dest != LO_SPACE && size <= Page::kMaxNonCodeHeapObjectSize);
-  // Objects in old pointer space and old data space can just be moved by
-  // compaction to a different page in the same space.
-  // TODO(hpayer): Replace that following checks with asserts.
-  CHECK(!heap_->old_pointer_space()->Contains(src) ||
-        (heap_->old_pointer_space()->Contains(dst) &&
-        heap_->TargetSpace(HeapObject::FromAddress(src)) ==
-        heap_->old_pointer_space()));
-  CHECK(!heap_->old_data_space()->Contains(src) ||
-        (heap_->old_data_space()->Contains(dst) &&
-        heap_->TargetSpace(HeapObject::FromAddress(src)) ==
-        heap_->old_data_space()));
   if (dest == OLD_POINTER_SPACE) {
     // TODO(hpayer): Replace this check with an assert.
-    CHECK(heap_->TargetSpace(HeapObject::FromAddress(src)) ==
-          heap_->old_pointer_space());
+    HeapObject* heap_object = HeapObject::FromAddress(src);
+    CHECK(heap_object->IsExternalString() ||
+          heap_->TargetSpace(heap_object) == heap_->old_pointer_space());
     Address src_slot = src;
     Address dst_slot = dst;
     ASSERT(IsAligned(size, kPointerSize));
@@ -2784,6 +2774,13 @@ void MarkCompactCollector::MigrateObject(Address dst,
     Code::cast(HeapObject::FromAddress(dst))->Relocate(dst - src);
   } else {
     ASSERT(dest == OLD_DATA_SPACE || dest == NEW_SPACE);
+    // Objects in old data space can just be moved by compaction to a different
+    // page in old data space.
+    // TODO(hpayer): Replace the following check with an assert.
+    CHECK(!heap_->old_data_space()->Contains(src) ||
+          (heap_->old_data_space()->Contains(dst) &&
+          heap_->TargetSpace(HeapObject::FromAddress(src)) ==
+          heap_->old_data_space()));
     heap()->MoveBlock(dst, src, size);
   }
   Memory::Address_at(src) = dst;