Support Smi->Double->HeapObject transitions in constructed Arrays.

src/objects-inl.h

 // Copyright 2011 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 1165 matching lines @@
 
 
 int HeapNumber::get_sign() {
   return READ_INT_FIELD(this, kExponentOffset) & kSignMask;
 }
 
 
 ACCESSORS(JSObject, properties, FixedArray, kPropertiesOffset)
 
 
+Object** FixedArray::GetFirstElementAddress() {
+  return reinterpret_cast<Object**>(FIELD_ADDR(this, OffsetOfElementAt(0)));
+}
+
+
+bool FixedArray::ContainsOnlySmisOrHoles() {
+  Object* the_hole = GetHeap()->the_hole_value();
+  Object** current = GetFirstElementAddress();
+  for (int i = 0; i < length(); ++i) {
+    Object* candidate = *current++;
+    if (!candidate->IsSmi() && candidate != the_hole) return false;
+  }
+  return true;
+}
+
+
 FixedArrayBase* JSObject::elements() {
   Object* array = READ_FIELD(this, kElementsOffset);
   return static_cast<FixedArrayBase*>(array);
 }
 
 void JSObject::ValidateSmiOnlyElements() {
 #if DEBUG
   if (map()->elements_kind() == FAST_SMI_ONLY_ELEMENTS) {
     Heap* heap = GetHeap();
     // Don't use elements, since integrity checks will fail if there
     // are filler pointers in the array.
     FixedArray* fixed_array =
         reinterpret_cast<FixedArray*>(READ_FIELD(this, kElementsOffset));
     Map* map = fixed_array->map();
     // Arrays that have been shifted in place can't be verified.
     if (map != heap->raw_unchecked_one_pointer_filler_map() &&
         map != heap->raw_unchecked_two_pointer_filler_map() &&
         map != heap->free_space_map()) {
       for (int i = 0; i < fixed_array->length(); i++) {
         Object* current = fixed_array->get(i);
         ASSERT(current->IsSmi() || current == heap->the_hole_value());
       }
     }
   }
 #endif
 }
 
 
-MaybeObject* JSObject::EnsureCanContainNonSmiElements() {
+MaybeObject* JSObject::EnsureCanContainHeapObjectElements() {
 #if DEBUG
   ValidateSmiOnlyElements();
 #endif
-  if ((map()->elements_kind() == FAST_SMI_ONLY_ELEMENTS)) {
-    Object* obj;
-    MaybeObject* maybe_obj = GetElementsTransitionMap(FAST_ELEMENTS);
-    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
-    set_map(Map::cast(obj));
+  if ((map()->elements_kind() != FAST_ELEMENTS)) {
+    return TransitionElementsKind(FAST_ELEMENTS);
   }
   return this;
 }
 
 
 MaybeObject* JSObject::EnsureCanContainElements(Object** objects,
-                                                uint32_t count) {
-  if (map()->elements_kind() == FAST_SMI_ONLY_ELEMENTS) {
-    for (uint32_t i = 0; i < count; ++i) {
-      Object* current = *objects++;
-      if (!current->IsSmi() && current != GetHeap()->the_hole_value()) {
-        return EnsureCanContainNonSmiElements();
+                                                uint32_t count,
+                                                EnsureElementsMode mode) {
+  ElementsKind current_kind = map()->elements_kind();
+  ElementsKind target_kind = current_kind;
+  ASSERT(mode != ALLOW_COPIED_DOUBLE_ELEMENTS);
+  if (current_kind == FAST_ELEMENTS) return this;
+
+  Heap* heap = GetHeap();
+  Object* the_hole = heap->the_hole_value();
+  Object* heap_number_map = heap->heap_number_map();
+  for (uint32_t i = 0; i < count; ++i) {
+    Object* current = *objects++;
+    if (!current->IsSmi() && current != the_hole) {
+      if (mode == ALLOW_CONVERTED_DOUBLE_ELEMENTS &&
+          HeapObject::cast(current)->map() == heap_number_map) {
+        target_kind = FAST_DOUBLE_ELEMENTS;
+      } else {
+        target_kind = FAST_ELEMENTS;
+        break;
       }
     }
   }
+
+  if (target_kind != current_kind) {
+    return TransitionElementsKind(target_kind);
+  }
   return this;
 }
 
 
-MaybeObject* JSObject::EnsureCanContainElements(FixedArray* elements) {
-  Object** objects = reinterpret_cast<Object**>(
-      FIELD_ADDR(elements, elements->OffsetOfElementAt(0)));
-  return EnsureCanContainElements(objects, elements->length());
+MaybeObject* JSObject::EnsureCanContainElements(FixedArrayBase* elements,
+                                                EnsureElementsMode mode) {
+  if (elements->map() != GetHeap()->fixed_double_array_map()) {
+    ASSERT(elements->map() == GetHeap()->fixed_array_map() ||
+           elements->map() == GetHeap()->fixed_cow_array_map());
+    if (mode == ALLOW_COPIED_DOUBLE_ELEMENTS) {
+      mode = DONT_ALLOW_DOUBLE_ELEMENTS;
+    }
+    Object** objects = FixedArray::cast(elements)->GetFirstElementAddress();
+    return EnsureCanContainElements(objects, elements->length(),
+                                    mode);

[Jakob Kummerow, 2011/12/07 17:02:47]

nit: no need for line break

[danno, 2011/12/08 15:09:09]

Done.

+  }
+
+  ASSERT(mode == ALLOW_COPIED_DOUBLE_ELEMENTS);
+  if (GetElementsKind() == FAST_SMI_ONLY_ELEMENTS) {
+    return TransitionElementsKind(FAST_DOUBLE_ELEMENTS);
+  }
+
+  return this;
 }
 
 
 void JSObject::set_elements(FixedArrayBase* value, WriteBarrierMode mode) {
   ASSERT((map()->has_fast_elements() ||
           map()->has_fast_smi_only_elements()) ==
          (value->map() == GetHeap()->fixed_array_map() ||
           value->map() == GetHeap()->fixed_cow_array_map()));
   ASSERT(map()->has_fast_double_elements() ==
          value->IsFixedDoubleArray());
@@ skipping 2857 matching lines @@
 ElementsKind JSObject::GetElementsKind() {
   ElementsKind kind = map()->elements_kind();
 #if DEBUG
   FixedArrayBase* fixed_array =
       reinterpret_cast<FixedArrayBase*>(READ_FIELD(this, kElementsOffset));
   Map* map = fixed_array->map();
     ASSERT(((kind == FAST_ELEMENTS || kind == FAST_SMI_ONLY_ELEMENTS) &&
             (map == GetHeap()->fixed_array_map() ||
              map == GetHeap()->fixed_cow_array_map())) ||
            (kind == FAST_DOUBLE_ELEMENTS &&
-            fixed_array->IsFixedDoubleArray()) ||
+            (fixed_array->IsFixedDoubleArray() ||
+            fixed_array == GetHeap()->empty_fixed_array())) ||
            (kind == DICTIONARY_ELEMENTS &&
             fixed_array->IsFixedArray() &&
             fixed_array->IsDictionary()) ||
            (kind > DICTIONARY_ELEMENTS));
     ASSERT((kind != NON_STRICT_ARGUMENTS_ELEMENTS) ||
            (elements()->IsFixedArray() && elements()->length() >= 2));
 #endif
   return kind;
 }
 
@@ skipping 438 matching lines @@
   }
 }
 
 
 void JSArray::set_length(Smi* length) {
   // Don't need a write barrier for a Smi.
   set_length(static_cast<Object*>(length), SKIP_WRITE_BARRIER);
 }
 
 
-MaybeObject* JSArray::SetContent(FixedArray* storage) {
-  MaybeObject* maybe_object = EnsureCanContainElements(storage);
-  if (maybe_object->IsFailure()) return maybe_object;
+MaybeObject* JSArray::SetContent(FixedArrayBase* storage) {
+  MaybeObject* maybe_result = EnsureCanContainElements(
+      storage, ALLOW_COPIED_DOUBLE_ELEMENTS);
+  if (maybe_result->IsFailure()) return maybe_result;
+  ASSERT((storage->map() == GetHeap()->fixed_double_array_map() &&
+          GetElementsKind() == FAST_DOUBLE_ELEMENTS) ||
+         ((storage->map() != GetHeap()->fixed_double_array_map()) &&
+          ((GetElementsKind() == FAST_ELEMENTS) ||
+           (GetElementsKind() == FAST_SMI_ONLY_ELEMENTS &&
+            FixedArray::cast(storage)->ContainsOnlySmisOrHoles()))));
+  set_elements(storage);
   set_length(Smi::FromInt(storage->length()));
-  set_elements(storage);
   return this;
 }
 
 
 MaybeObject* FixedArray::Copy() {
   if (length() == 0) return this;
   return GetHeap()->CopyFixedArray(this);
 }
 
 
@@ skipping 103 matching lines @@
 #undef WRITE_INT_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_