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

src/layout-descriptor-inl.h

-// Copyright 2014 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef V8_LAYOUT_DESCRIPTOR_INL_H_
-#define V8_LAYOUT_DESCRIPTOR_INL_H_
-
-#include "src/layout-descriptor.h"
-
-namespace v8 {
-namespace internal {
-
-LayoutDescriptor* LayoutDescriptor::FromSmi(Smi* smi) {
-  return LayoutDescriptor::cast(smi);
-}
-
-
-Handle<LayoutDescriptor> LayoutDescriptor::New(Isolate* isolate, int length) {
-  if (length <= kSmiValueSize) {
-    // The whole bit vector fits into a smi.
-    return handle(LayoutDescriptor::FromSmi(Smi::FromInt(0)), isolate);
-  }
-
-  length = (length + kNumberOfBits - 1) / kNumberOfBits;
-  DCHECK(length > 0);
-
-  if (SmiValuesAre32Bits() && (length & 1)) {
-    // On 64-bit systems if the length is odd then the half-word space would be
-    // lost anyway (due to alignment and the fact that we are allocating
-    // uint32-typed array), so we increase the length of allocated array
-    // to utilize that "lost" space which could also help to avoid layout
-    // descriptor reallocations.
-    ++length;
-  }
-  return Handle<LayoutDescriptor>::cast(
-      isolate->factory()->NewFixedTypedArray(length, kExternalUint32Array));
-}
-
-
-bool LayoutDescriptor::InobjectUnboxedField(int inobject_properties,
-                                            PropertyDetails details) {
-  if (details.type() != FIELD || !details.representation().IsDouble()) {
-    return false;
-  }
-  // We care only about in-object properties.
-  return details.field_index() < inobject_properties;
-}
-
-
-LayoutDescriptor* LayoutDescriptor::FastPointerLayout() {
-  return LayoutDescriptor::FromSmi(Smi::FromInt(0));
-}
-
-
-bool LayoutDescriptor::GetIndexes(int field_index, int* layout_word_index,
-                                  uint32_t* layout_mask) {
-  if (static_cast<unsigned>(field_index) >= static_cast<unsigned>(capacity())) {
-    return false;
-  }
-
-  *layout_word_index = field_index / kNumberOfBits;
-  CHECK((!IsSmi() && (*layout_word_index < length())) ||
-        (IsSmi() && (*layout_word_index < 1)));
-
-  int layout_bit_index = field_index % kNumberOfBits;
-  *layout_mask = static_cast<uint32_t>(1) << layout_bit_index;
-  return true;
-}
-
-
-LayoutDescriptor* LayoutDescriptor::SetTagged(int field_index, bool tagged) {
-  int layout_word_index;
-  uint32_t layout_mask;
-
-  if (!GetIndexes(field_index, &layout_word_index, &layout_mask)) {
-    CHECK(false);
-    return this;
-  }
-
-  if (IsSlowLayout()) {
-    uint32_t value = get_scalar(layout_word_index);
-    if (tagged) {
-      value &= ~layout_mask;
-    } else {
-      value |= layout_mask;
-    }
-    set(layout_word_index, value);
-    return this;
-  } else {
-    uint32_t value = static_cast<uint32_t>(Smi::cast(this)->value());
-    if (tagged) {
-      value &= ~layout_mask;
-    } else {
-      value |= layout_mask;
-    }
-    return LayoutDescriptor::FromSmi(Smi::FromInt(static_cast<int>(value)));
-  }
-}
-
-
-bool LayoutDescriptor::IsTagged(int field_index) {
-  if (IsFastPointerLayout()) return true;
-
-  int layout_word_index;
-  uint32_t layout_mask;
-
-  if (!GetIndexes(field_index, &layout_word_index, &layout_mask)) {
-    // All bits after Out of bounds queries
-    return true;
-  }
-
-  if (IsSlowLayout()) {
-    uint32_t value = get_scalar(layout_word_index);
-    return (value & layout_mask) == 0;
-  } else {
-    uint32_t value = static_cast<uint32_t>(Smi::cast(this)->value());
-    return (value & layout_mask) == 0;
-  }
-}
-
-
-bool LayoutDescriptor::IsFastPointerLayout() {
-  return IsSmi() && (Smi::cast(this)->value() == 0);
-}
-
-
-bool LayoutDescriptor::IsSlowLayout() { return !IsSmi(); }
-
-
-int LayoutDescriptor::capacity() {
-  return IsSlowLayout() ? (length() * kNumberOfBits) : kSmiValueSize;
-}
-
-
-LayoutDescriptor* LayoutDescriptor::cast_gc_safe(Object* object) {
-  if (object->IsSmi()) {
-    // Fast mode layout descriptor.
-    return reinterpret_cast<LayoutDescriptor*>(object);
-  }
-
-  // This is a mixed descriptor which is a fixed typed array.
-  MapWord map_word = reinterpret_cast<HeapObject*>(object)->map_word();
-  if (map_word.IsForwardingAddress()) {
-    // Mark-compact has already moved layout descriptor.
-    object = map_word.ToForwardingAddress();
-  }
-  return LayoutDescriptor::cast(object);
-}
-
-
-// InobjectPropertiesHelper is a helper class for querying whether inobject
-// property at offset is Double or not.
-InobjectPropertiesHelper::InobjectPropertiesHelper(Map* map)
-    : all_fields_tagged_(true),
-      header_size_(0),
-      layout_descriptor_(LayoutDescriptor::FastPointerLayout()) {
-  if (!FLAG_unbox_double_fields) return;
-
-  layout_descriptor_ = map->layout_descriptor_gc_safe();
-  if (layout_descriptor_->IsFastPointerLayout()) {
-    return;
-  }
-
-  int inobject_properties = map->inobject_properties();
-  DCHECK(inobject_properties > 0);
-  header_size_ = map->instance_size() - (inobject_properties * kPointerSize);
-  DCHECK(header_size_ >= 0);
-
-  all_fields_tagged_ = false;
-}
-
-
-bool InobjectPropertiesHelper::IsTagged(int offset_in_bytes) {
-  DCHECK(IsAligned(offset_in_bytes, kPointerSize));
-  if (all_fields_tagged_) return true;
-  // Object headers do not contain non-tagged fields.
-  if (offset_in_bytes < header_size_) return true;
-  int field_index = (offset_in_bytes - header_size_) / kPointerSize;
-
-  return layout_descriptor_->IsTagged(field_index);
-}
-}
-}  // namespace v8::internal
-
-#endif  // V8_LAYOUT_DESCRIPTOR_INL_H_