Separating transitions from descriptors.

src/transitions-inl.h

+// Copyright 2012 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_TRANSITIONS_INL_H_
+#define V8_TRANSITIONS_INL_H_
+
+#include "objects.h"
+#include "objects-inl.h"
+#include "transitions.h"
+
+namespace v8 {
+namespace internal {
+
+
+#define FIELD_ADDR(p, offset) \
+  (reinterpret_cast<byte*>(p) + offset - kHeapObjectTag)
+
+#define WRITE_FIELD(p, offset, value) \
+  (*reinterpret_cast<Object**>(FIELD_ADDR(p, offset)) = value)
+
+#define CONDITIONAL_WRITE_BARRIER(heap, object, offset, value, mode)    \
+  if (mode == UPDATE_WRITE_BARRIER) {                                   \
+    heap->incremental_marking()->RecordWrite(                           \
+      object, HeapObject::RawField(object, offset), value);             \
+    if (heap->InNewSpace(value)) {                                      \
+      heap->RecordWrite(object->address(), offset);                     \
+    }                                                                   \
+  }
+
+
+TransitionArray* TransitionArray::cast(Object* object) {
+  ASSERT(object->IsTransitionArray());
+  return reinterpret_cast<TransitionArray*>(object);
+}
+
+
+Map* TransitionArray::elements_transition() {
+  Object* transition_map = get(kElementsTransitionIndex);
+  return Map::cast(transition_map);
+}
+
+
+void TransitionArray::ClearElementsTransition() {
+  WRITE_FIELD(this, kElementsTransitionOffset, Smi::FromInt(0));
+}
+
+
+bool TransitionArray::HasElementsTransition() {
+  return get(kElementsTransitionIndex) != Smi::FromInt(0);
+}
+
+
+void TransitionArray::set_elements_transition(
+    Map* transition_map, WriteBarrierMode mode) {
+  ASSERT(this != NULL);
+  Heap* heap = GetHeap();
+  WRITE_FIELD(this, kElementsTransitionOffset, transition_map);
+  CONDITIONAL_WRITE_BARRIER(
+      heap, this, kElementsTransitionOffset, transition_map, mode);
+}
+
+
+Object** TransitionArray::GetKeySlot(int transition_number) {
+  ASSERT(transition_number < number_of_transitions());
+  return HeapObject::RawField(
+      reinterpret_cast<HeapObject*>(this),
+      OffsetOfElementAt(ToKeyIndex(transition_number)));
+}
+
+
+String* TransitionArray::GetKey(int transition_number) {
+  ASSERT(transition_number < number_of_transitions());
+  return String::cast(get(ToKeyIndex(transition_number)));
+}
+
+
+void TransitionArray::SetKeyUnchecked(Heap* heap,
+                                      int transition_number,
+                                      String* key) {
+  ASSERT(transition_number < number_of_transitions());
+  set_unchecked(heap,
+                ToKeyIndex(transition_number),
+                key,
+                UPDATE_WRITE_BARRIER);
+}
+
+
+Object* TransitionArray::GetValue(int transition_number) {
+  ASSERT(transition_number < number_of_transitions());
+  return get(ToValueIndex(transition_number));
+}
+
+
+Object** TransitionArray::GetValueSlot(int transition_number) {
+  ASSERT(transition_number < number_of_transitions());
+  return HeapObject::RawField(
+      reinterpret_cast<HeapObject*>(this),
+      OffsetOfElementAt(ToValueIndex(transition_number)));
+}
+
+
+void TransitionArray::SetValueUnchecked(Heap* heap,
+                                        int transition_number,
+                                        Object* value) {
+  ASSERT(transition_number < number_of_transitions());
+  set_unchecked(heap,
+                ToValueIndex(transition_number),
+                value,
+                UPDATE_WRITE_BARRIER);
+}
+
+
+Map* TransitionArray::GetTargetMap(int transition_number) {
+  Object* value = GetValue(transition_number);
+  if (value->IsAccessorPair()) {
+    // TODO(verwaest) Currently details are always taken from the getter if it
+    // is a transition, otherwise from the setter which in that case has to be
+    // a transition. Details should be dependent on which component is
+    // requested.
+    AccessorPair* accessors = AccessorPair::cast(value);
+    if (accessors->getter()->IsMap()) {
+      return Map::cast(accessors->getter());
+    }
+    return Map::cast(accessors->setter());
+  }
+  return Map::cast(value);
+}
+
+
+PropertyDetails TransitionArray::GetTargetDetails(int transition_number) {
+  Map* map = GetTargetMap(transition_number);
+  DescriptorArray* descriptors = map->instance_descriptors();
+  String* key = GetKey(transition_number);
+  int descriptor = descriptors->SearchWithCache(key);
+  ASSERT(descriptor != DescriptorArray::kNotFound);
+  return descriptors->GetDetails(descriptor);
+}
+
+
+Object** TransitionArray::GetElementsSlot() {
+  return HeapObject::RawField(reinterpret_cast<HeapObject*>(this),
+                              kElementsTransitionOffset);
+}
+
+
+int TransitionArray::Search(String* name) {
+  return internal::Search(this, name);
+}
+
+
+void TransitionArray::Set(int transition_number, String* key, Object* value) {

[Michael Starzinger, 2012/07/05 12:55:51]

This setter should take a WhitenessWitness as the last argument. This will
require a slight generalization of that class, because it is no longer specific
to the DescriptorArray.

+  NoIncrementalWriteBarrierSet(this,
+                               ToKeyIndex(transition_number),
+                               key);

[Michael Starzinger, 2012/07/05 12:55:51]

Actually I think it might be a good idea to pass the WhitenessWitness into
NoIncrementalWriteBarrierSet() as well, to catch these cases statically.

+  NoIncrementalWriteBarrierSet(this,
+                               ToValueIndex(transition_number),
+                               value);
+}
+
+
+#undef FIELD_ADDR
+#undef WRITE_FIELD
+#undef CONDITIONAL_WRITE_BARRIER
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_TRANSITIONS_INL_H_