Basic support for tracking smi-only arrays on ia32.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 5fadaa98d738c65efef363466fa7adca5be850ac..3b3f6259d69cae7cce9d33976acdd4114f470afa 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -1300,14 +1300,82 @@ FixedArrayBase* JSObject::elements() {
   return static_cast<FixedArrayBase*>(array);
 }
 
+void JSObject::ValidateSmiOnlyElements() {
+#if DEBUG
+  if (FLAG_smi_only_arrays &&
+      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() {
+#if DEBUG
+  ValidateSmiOnlyElements();
+#endif
+  if (FLAG_smi_only_arrays &&
+      (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));
+  }
+  return this;
+}
+
+
+MaybeObject* JSObject::EnsureCanContainElements(Object** objects,
+                                                uint32_t count) {
+  if (FLAG_smi_only_arrays &&
+      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();
+      }
+    }
+  }
+  return this;
+}
+
+
+MaybeObject* JSObject::EnsureCanContainElements(FixedArray* elements) {
+  if (FLAG_smi_only_arrays) {
+    Object** objects = reinterpret_cast<Object**>(
+        FIELD_ADDR(elements, elements->OffsetOfElementAt(0)));
+    return EnsureCanContainElements(objects, elements->length());
+  } else {
+    return this;
+  }
+}
+
 
 void JSObject::set_elements(FixedArrayBase* value, WriteBarrierMode mode) {
-  ASSERT(map()->has_fast_elements() ==
+  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());
   ASSERT(value->HasValidElements());
+#ifdef DEBUG
+  ValidateSmiOnlyElements();
+#endif
   WRITE_FIELD(this, kElementsOffset, value);
   CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kElementsOffset, value, mode);
 }
@@ -1320,7 +1388,7 @@ void JSObject::initialize_properties() {
 
 
 void JSObject::initialize_elements() {
-  ASSERT(map()->has_fast_elements());
+  ASSERT(map()->has_fast_elements() || map()->has_fast_smi_only_elements());
   ASSERT(!GetHeap()->InNewSpace(GetHeap()->empty_fixed_array()));
   WRITE_FIELD(this, kElementsOffset, GetHeap()->empty_fixed_array());
 }
@@ -1328,9 +1396,11 @@ void JSObject::initialize_elements() {
 
 MaybeObject* JSObject::ResetElements() {
   Object* obj;
-  { MaybeObject* maybe_obj = GetElementsTransitionMap(FAST_ELEMENTS);
-    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
-  }
+  ElementsKind elements_kind = FLAG_smi_only_arrays
+      ? FAST_SMI_ONLY_ELEMENTS
+      : FAST_ELEMENTS;
+  MaybeObject* maybe_obj = GetElementsTransitionMap(elements_kind);
+  if (!maybe_obj->ToObject(&obj)) return maybe_obj;
   set_map(Map::cast(obj));
   initialize_elements();
   return this;
@@ -1686,7 +1756,7 @@ void FixedDoubleArray::Initialize(FixedDoubleArray* from) {
 
 void FixedDoubleArray::Initialize(FixedArray* from) {
   int old_length = from->length();
-  ASSERT(old_length < length());
+  ASSERT(old_length <= length());
   for (int i = 0; i < old_length; i++) {
     Object* hole_or_object = from->get(i);
     if (hole_or_object->IsTheHole()) {
@@ -3957,15 +4027,20 @@ void JSRegExp::SetDataAtUnchecked(int index, Object* value, Heap* heap) {
 
 ElementsKind JSObject::GetElementsKind() {
   ElementsKind kind = map()->elements_kind();
-  ASSERT((kind == FAST_ELEMENTS &&
-          (elements()->map() == GetHeap()->fixed_array_map() ||
-           elements()->map() == GetHeap()->fixed_cow_array_map())) ||
+#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 &&
-          elements()->IsFixedDoubleArray()) ||
+          fixed_array->IsFixedDoubleArray()) ||
          (kind == DICTIONARY_ELEMENTS &&
-          elements()->IsFixedArray() &&
-          elements()->IsDictionary()) ||
+          fixed_array->IsFixedArray() &&
+          fixed_array->IsDictionary()) ||
          (kind > DICTIONARY_ELEMENTS));
+#endif
   return kind;
 }
 
@@ -3980,6 +4055,18 @@ bool JSObject::HasFastElements() {
 }
 
 
+bool JSObject::HasFastSmiOnlyElements() {
+  return GetElementsKind() == FAST_SMI_ONLY_ELEMENTS;
+}
+
+
+bool JSObject::HasFastTypeElements() {
+  ElementsKind elements_kind = GetElementsKind();
+  return elements_kind == FAST_SMI_ONLY_ELEMENTS ||
+      elements_kind == FAST_ELEMENTS;
+}
+
+
 bool JSObject::HasFastDoubleElements() {
   return GetElementsKind() == FAST_DOUBLE_ELEMENTS;
 }
@@ -3990,6 +4077,11 @@ bool JSObject::HasDictionaryElements() {
 }
 
 
+bool JSObject::HasNonStrictArgumentsElements() {
+  return GetElementsKind() == NON_STRICT_ARGUMENTS_ELEMENTS;
+}
+
+
 bool JSObject::HasExternalArrayElements() {
   HeapObject* array = elements();
   ASSERT(array != NULL);
@@ -4041,7 +4133,7 @@ bool JSObject::AllowsSetElementsLength() {
 
 
 MaybeObject* JSObject::EnsureWritableFastElements() {
-  ASSERT(HasFastElements());
+  ASSERT(HasFastTypeElements());
   FixedArray* elems = FixedArray::cast(elements());
   Isolate* isolate = GetIsolate();
   if (elems->map() != isolate->heap()->fixed_cow_array_map()) return elems;
@@ -4409,7 +4501,7 @@ void Map::ClearCodeCache(Heap* heap) {
 
 
 void JSArray::EnsureSize(int required_size) {
-  ASSERT(HasFastElements());
+  ASSERT(HasFastTypeElements());
   FixedArray* elts = FixedArray::cast(elements());
   const int kArraySizeThatFitsComfortablyInNewSpace = 128;
   if (elts->length() < required_size) {
@@ -4432,9 +4524,12 @@ void JSArray::set_length(Smi* length) {
 }
 
 
-void JSArray::SetContent(FixedArray* storage) {
+MaybeObject* JSArray::SetContent(FixedArray* storage) {
+  MaybeObject* maybe_object = EnsureCanContainElements(storage);
+  if (maybe_object->IsFailure()) return maybe_object;
   set_length(Smi::FromInt(storage->length()));
   set_elements(storage);
+  return this;
 }