In-object double fields unboxing (for 64-bit only).

src/objects-debug.cc

Index: src/objects-debug.cc
diff --git a/src/objects-debug.cc b/src/objects-debug.cc
index ca649c723168f85d5582ece7e3ff8d7a10b995cb..94957206548ec3d3ab63ee251526abcf96a042f5 100644
--- a/src/objects-debug.cc
+++ b/src/objects-debug.cc
@@ -275,6 +275,10 @@ void JSObject::JSObjectVerify() {
       if (descriptors->GetDetails(i).type() == FIELD) {
         Representation r = descriptors->GetDetails(i).representation();
         FieldIndex index = FieldIndex::ForDescriptor(map(), i);
+        if (IsUnboxedDoubleField(index)) {
+          DCHECK(r.IsDouble());
+          continue;
+        }
         Object* value = RawFastPropertyAt(index);
         if (r.IsDouble()) DCHECK(value->IsMutableHeapNumber());
         if (value->IsUninitialized()) continue;
@@ -316,6 +320,8 @@ void Map::MapVerify() {
     SLOW_DCHECK(transitions()->IsSortedNoDuplicates());
     SLOW_DCHECK(transitions()->IsConsistentWithBackPointers(this));
   }
+  SLOW_DCHECK(!FLAG_unbox_double_fields ||
+              layout_descriptor()->IsConsistentWithMap(this));
 }
 
 
@@ -325,8 +331,7 @@ void Map::DictionaryMapVerify() {
   CHECK(instance_descriptors()->IsEmpty());
   CHECK_EQ(0, pre_allocated_property_fields());
   CHECK_EQ(0, unused_property_fields());
-  CHECK_EQ(StaticVisitorBase::GetVisitorId(instance_type(), instance_size()),
-      visitor_id());
+  CHECK_EQ(StaticVisitorBase::GetVisitorId(this), visitor_id());
 }
 
 
@@ -1179,6 +1184,27 @@ bool DescriptorArray::IsSortedNoDuplicates(int valid_entries) {
 }
 
 
+bool LayoutDescriptor::IsConsistentWithMap(Map* map) {
+  if (FLAG_unbox_double_fields) {
+    DescriptorArray* descriptors = map->instance_descriptors();
+    int nof_descriptors = map->NumberOfOwnDescriptors();
+    for (int i = 0; i < nof_descriptors; i++) {
+      PropertyDetails details = descriptors->GetDetails(i);
+      if (details.type() != FIELD) continue;
+      FieldIndex field_index = FieldIndex::ForDescriptor(map, i);
+      bool tagged_expected =
+          !field_index.is_inobject() || !details.representation().IsDouble();
+      for (int bit = 0; bit < details.field_width_in_words(); bit++) {
+        bool tagged_actual = IsTagged(details.field_index() + bit);
+        DCHECK_EQ(tagged_expected, tagged_actual);
+        if (tagged_actual != tagged_expected) return false;
+      }
+    }
+  }
+  return true;
+}
+
+
 bool TransitionArray::IsSortedNoDuplicates(int valid_entries) {
   DCHECK(valid_entries == -1);
   Name* prev_key = NULL;