Basic support for tracking smi-only arrays on ia32.

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 1383 matching lines @@
 ACCESSORS(JSObject, properties, FixedArray, kPropertiesOffset)
 
 
 FixedArrayBase* JSObject::elements() {
   Object* array = READ_FIELD(this, kElementsOffset);
   ASSERT(array->HasValidElements());
   return static_cast<FixedArrayBase*>(array);
 }
 
 
+MaybeObject* JSObject::EnsureCanContainNonSmiElements() {
+  if (FLAG_smi_only_arrays &&
+      (map()->elements_kind() == FAST_SMI_ONLY_ELEMENTS)) {
+#ifdef DEBUG
+    Heap* heap = GetHeap();
+    FixedArray* fixed_array = FixedArray::cast(elements());
+    for (int i = 0; i < fixed_array->length(); i++) {
+      Object* current = fixed_array->get(i);
+      ASSERT(current->IsSmi() || current == heap->the_hole_value());
+    }
+#endif
+    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
+  if (map()->elements_kind() == FAST_SMI_ONLY_ELEMENTS) {
+    Heap* heap = GetHeap();

[Sven Panne, 2011/09/16 09:19:32]

Copy-n-paste from above, perhaps introduce a helper method like AllIsSmiOrHole?

[danno, 2011/09/21 14:32:04]

Done.

+    for (int i = 0; i < value->length(); i++) {
+      Object* current = FixedArray::cast(value)->get(i);
+      ASSERT(current->IsSmi() || current == heap->the_hole_value());
+    }
+  }
+#endif
   WRITE_FIELD(this, kElementsOffset, value);
   CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kElementsOffset, mode);
 }
 
 
 void JSObject::initialize_properties() {
   ASSERT(!GetHeap()->InNewSpace(GetHeap()->empty_fixed_array()));
   WRITE_FIELD(this, kPropertiesOffset, GetHeap()->empty_fixed_array());
 }
 
 
 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());
 }
 
 
 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;
 }
 
 
 ACCESSORS(Oddball, to_string, String, kToStringOffset)
 ACCESSORS(Oddball, to_number, Object, kToNumberOffset)
 
 
@@ skipping 317 matching lines @@
   int offset = kHeaderSize + old_length * kDoubleSize;
   for (int current = from->length(); current < length(); ++current) {
     WRITE_DOUBLE_FIELD(this, offset, hole_nan_as_double());
     offset += kDoubleSize;
   }
 }
 
 
 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()) {
       set_the_hole(i);
     } else {
       set(i, hole_or_object->Number());
     }
   }
   int offset = kHeaderSize + old_length * kDoubleSize;
   for (int current = from->length(); current < length(); ++current) {
@@ skipping 2276 matching lines @@
   if (value->IsSmi()) {
     fa->set_unchecked(index, Smi::cast(value));
   } else {
     fa->set_unchecked(heap, index, value, SKIP_WRITE_BARRIER);
   }
 }
 
 
 ElementsKind JSObject::GetElementsKind() {
   ElementsKind kind = map()->elements_kind();
-  ASSERT((kind == FAST_ELEMENTS &&
+  ASSERT(((kind == FAST_ELEMENTS || kind == FAST_SMI_ONLY_ELEMENTS) &&
           (elements()->map() == GetHeap()->fixed_array_map() ||
            elements()->map() == GetHeap()->fixed_cow_array_map())) ||
          (kind == FAST_DOUBLE_ELEMENTS &&
           elements()->IsFixedDoubleArray()) ||
          (kind == DICTIONARY_ELEMENTS &&
           elements()->IsFixedArray() &&
           elements()->IsDictionary()) ||
          (kind > DICTIONARY_ELEMENTS));
   return kind;
 }
 
 
 ElementsAccessor* JSObject::GetElementsAccessor() {
   return ElementsAccessor::ForKind(GetElementsKind());
 }
 
 
 bool JSObject::HasFastElements() {
   return GetElementsKind() == FAST_ELEMENTS;
 }
 
 
+bool JSObject::HasFastSmiOnlyElements() {
+  return GetElementsKind() == FAST_SMI_ONLY_ELEMENTS;
+}
+
+
 bool JSObject::HasFastDoubleElements() {
   return GetElementsKind() == FAST_DOUBLE_ELEMENTS;
 }
 
 
 bool JSObject::HasDictionaryElements() {
   return GetElementsKind() == DICTIONARY_ELEMENTS;
 }
 
 
+bool JSObject::HasNonStrictArgumentsElements() {
+  return GetElementsKind() == NON_STRICT_ARGUMENTS_ELEMENTS;
+}
+
+
 bool JSObject::HasExternalArrayElements() {
   HeapObject* array = elements();
   ASSERT(array != NULL);
   return array->IsExternalArray();
 }
 
 
 #define EXTERNAL_ELEMENTS_CHECK(name, type)          \
 bool JSObject::HasExternal##name##Elements() {       \
   HeapObject* array = elements();                    \
@@ skipping 31 matching lines @@
 
 bool JSObject::AllowsSetElementsLength() {
   bool result = elements()->IsFixedArray() ||
       elements()->IsFixedDoubleArray();
   ASSERT(result == !HasExternalArrayElements());
   return result;
 }
 
 
 MaybeObject* JSObject::EnsureWritableFastElements() {
-  ASSERT(HasFastElements());
+  ASSERT(HasFastElements() || HasFastSmiOnlyElements());
   FixedArray* elems = FixedArray::cast(elements());
   Isolate* isolate = GetIsolate();
   if (elems->map() != isolate->heap()->fixed_cow_array_map()) return elems;
   Object* writable_elems;
   { MaybeObject* maybe_writable_elems = isolate->heap()->CopyFixedArrayWithMap(
       elems, isolate->heap()->fixed_array_map());
     if (!maybe_writable_elems->ToObject(&writable_elems)) {
       return maybe_writable_elems;
     }
   }
@@ skipping 344 matching lines @@
 void Map::ClearCodeCache(Heap* heap) {
   // No write barrier is needed since empty_fixed_array is not in new space.
   // Please note this function is used during marking:
   //  - MarkCompactCollector::MarkUnmarkedObject
   ASSERT(!heap->InNewSpace(heap->raw_unchecked_empty_fixed_array()));
   WRITE_FIELD(this, kCodeCacheOffset, heap->raw_unchecked_empty_fixed_array());
 }
 
 
 void JSArray::EnsureSize(int required_size) {
-  ASSERT(HasFastElements());
+  ASSERT(HasFastElements() || HasFastSmiOnlyElements());
   FixedArray* elts = FixedArray::cast(elements());
   const int kArraySizeThatFitsComfortablyInNewSpace = 128;
   if (elts->length() < required_size) {
     // Doubling in size would be overkill, but leave some slack to avoid
     // constantly growing.
     Expand(required_size + (required_size >> 3));
     // It's a performance benefit to keep a frequently used array in new-space.
   } else if (!GetHeap()->new_space()->Contains(elts) &&
              required_size < kArraySizeThatFitsComfortablyInNewSpace) {
     // Expand will allocate a new backing store in new space even if the size
     // we asked for isn't larger than what we had before.
     Expand(required_size);
   }
 }
 
 
 void JSArray::set_length(Smi* length) {
   set_length(static_cast<Object*>(length), SKIP_WRITE_BARRIER);
 }
 
 
-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;
 }
 
 
 MaybeObject* FixedArray::Copy() {
   if (length() == 0) return this;
   return GetHeap()->CopyFixedArray(this);
 }
 
 
 Relocatable::Relocatable(Isolate* isolate) {
@@ skipping 96 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_