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

src/layout-descriptor.cc

-// 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.
-
-#include <sstream>
-
-#include "src/v8.h"
-
-#include "src/layout-descriptor.h"
-
-namespace v8 {
-namespace internal {
-
-Handle<LayoutDescriptor> LayoutDescriptor::New(
-    Handle<Map> map, Handle<DescriptorArray> descriptors, int num_descriptors) {
-  Isolate* isolate = descriptors->GetIsolate();
-  if (!FLAG_unbox_double_fields) return handle(FastPointerLayout(), isolate);
-
-  int inobject_properties = map->inobject_properties();
-  if (inobject_properties == 0) return handle(FastPointerLayout(), isolate);
-
-  DCHECK(num_descriptors <= descriptors->number_of_descriptors());
-
-  int layout_descriptor_length;
-  const int kMaxWordsPerField = kDoubleSize / kPointerSize;
-
-  if (num_descriptors <= kSmiValueSize / kMaxWordsPerField) {
-    // Even in the "worst" case (all fields are doubles) it would fit into
-    // a Smi, so no need to calculate length.
-    layout_descriptor_length = kSmiValueSize;
-
-  } else {
-    layout_descriptor_length = 0;
-
-    for (int i = 0; i < num_descriptors; i++) {
-      PropertyDetails details = descriptors->GetDetails(i);
-      if (!InobjectUnboxedField(inobject_properties, details)) continue;
-      int field_index = details.field_index();
-      int field_width_in_words = details.field_width_in_words();
-      layout_descriptor_length =
-          Max(layout_descriptor_length, field_index + field_width_in_words);
-    }
-
-    if (layout_descriptor_length == 0) {
-      // No double fields were found, use fast pointer layout.
-      return handle(FastPointerLayout(), isolate);
-    }
-  }
-  layout_descriptor_length = Min(layout_descriptor_length, inobject_properties);
-
-  // Initially, layout descriptor corresponds to an object with all fields
-  // tagged.
-  Handle<LayoutDescriptor> layout_descriptor_handle =
-      LayoutDescriptor::New(isolate, layout_descriptor_length);
-
-  DisallowHeapAllocation no_allocation;
-  LayoutDescriptor* layout_descriptor = *layout_descriptor_handle;
-
-  for (int i = 0; i < num_descriptors; i++) {
-    PropertyDetails details = descriptors->GetDetails(i);
-    if (!InobjectUnboxedField(inobject_properties, details)) continue;
-    int field_index = details.field_index();
-    layout_descriptor = layout_descriptor->SetRawData(field_index);
-    if (details.field_width_in_words() > 1) {
-      layout_descriptor = layout_descriptor->SetRawData(field_index + 1);
-    }
-  }
-  return handle(layout_descriptor, isolate);
-}
-
-
-Handle<LayoutDescriptor> LayoutDescriptor::Append(Handle<Map> map,
-                                                  PropertyDetails details) {
-  Handle<LayoutDescriptor> layout_descriptor = map->GetLayoutDescriptor();
-
-  if (!InobjectUnboxedField(map->inobject_properties(), details)) {
-    return layout_descriptor;
-  }
-  Isolate* isolate = map->GetIsolate();
-  int field_index = details.field_index();
-  layout_descriptor = LayoutDescriptor::EnsureCapacity(
-      isolate, layout_descriptor, field_index + details.field_width_in_words());
-
-  DisallowHeapAllocation no_allocation;
-  LayoutDescriptor* layout_desc = *layout_descriptor;
-  layout_desc = layout_desc->SetRawData(field_index);
-  if (details.field_width_in_words() > 1) {
-    layout_desc = layout_desc->SetRawData(field_index + 1);
-  }
-  return handle(layout_desc, isolate);
-}
-
-
-Handle<LayoutDescriptor> LayoutDescriptor::AppendIfFastOrUseFull(
-    Handle<Map> map, PropertyDetails details,
-    Handle<LayoutDescriptor> full_layout_descriptor) {
-  DisallowHeapAllocation no_allocation;
-  LayoutDescriptor* layout_descriptor = map->layout_descriptor();
-  if (layout_descriptor->IsSlowLayout()) {
-    return full_layout_descriptor;
-  }
-  if (!InobjectUnboxedField(map->inobject_properties(), details)) {
-    return handle(layout_descriptor, map->GetIsolate());
-  }
-  int field_index = details.field_index();
-  int new_capacity = field_index + details.field_width_in_words();
-  if (new_capacity > layout_descriptor->capacity()) {
-    // Current map's layout descriptor runs out of space, so use the full
-    // layout descriptor.
-    return full_layout_descriptor;
-  }
-
-  layout_descriptor = layout_descriptor->SetRawData(field_index);
-  if (details.field_width_in_words() > 1) {
-    layout_descriptor = layout_descriptor->SetRawData(field_index + 1);
-  }
-  return handle(layout_descriptor, map->GetIsolate());
-}
-
-
-Handle<LayoutDescriptor> LayoutDescriptor::EnsureCapacity(
-    Isolate* isolate, Handle<LayoutDescriptor> layout_descriptor,
-    int new_capacity) {
-  int old_capacity = layout_descriptor->capacity();
-  if (new_capacity <= old_capacity) {
-    // Nothing to do with layout in Smi-form.
-    return layout_descriptor;
-  }
-  Handle<LayoutDescriptor> new_layout_descriptor =
-      LayoutDescriptor::New(isolate, new_capacity);
-  DCHECK(new_layout_descriptor->IsSlowLayout());
-
-  if (layout_descriptor->IsSlowLayout()) {
-    memcpy(new_layout_descriptor->DataPtr(), layout_descriptor->DataPtr(),
-           layout_descriptor->DataSize());
-    return new_layout_descriptor;
-  } else {
-    // Fast layout.
-    uint32_t value =
-        static_cast<uint32_t>(Smi::cast(*layout_descriptor)->value());
-    new_layout_descriptor->set(0, value);
-    return new_layout_descriptor;
-  }
-}
-}
-}  // namespace v8::internal