48e5ec9ea6
Unaligned access is still unused, but will be necessary to load String-length once we store it as an int32 next to the hash-field. Bug: v8:7065 Change-Id: I7fa9364e062774c0a6b32e7f961031dcd30c564c Reviewed-on: https://chromium-review.googlesource.com/763349 Commit-Queue: Toon Verwaest <verwaest@chromium.org> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org> Cr-Commit-Position: refs/heads/master@{#49358}
103 lines
3.9 KiB
C++
103 lines
3.9 KiB
C++
// Copyright 2014 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_FIELD_INDEX_INL_H_
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#define V8_FIELD_INDEX_INL_H_
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#include "src/field-index.h"
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#include "src/objects-inl.h"
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#include "src/objects/descriptor-array.h"
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namespace v8 {
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namespace internal {
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inline FieldIndex FieldIndex::ForInObjectOffset(int offset, Encoding encoding,
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const Map* map) {
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DCHECK(map == nullptr || offset < map->instance_size());
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DCHECK(encoding == kWord32 ? (offset % kInt32Size) == 0
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: (offset % kPointerSize) == 0);
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return FieldIndex(true, offset, encoding, 0, 0);
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}
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inline FieldIndex FieldIndex::ForPropertyIndex(const Map* map,
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int property_index,
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Representation representation) {
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DCHECK(map->instance_type() >= FIRST_NONSTRING_TYPE);
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int inobject_properties = map->GetInObjectProperties();
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bool is_inobject = property_index < inobject_properties;
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int first_inobject_offset;
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int offset;
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if (is_inobject) {
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first_inobject_offset = map->GetInObjectPropertyOffset(0);
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offset = map->GetInObjectPropertyOffset(property_index);
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} else {
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first_inobject_offset = FixedArray::kHeaderSize;
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property_index -= inobject_properties;
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offset = FixedArray::kHeaderSize + property_index * kPointerSize;
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}
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Encoding encoding = FieldEncoding(representation);
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return FieldIndex(is_inobject, offset, encoding, inobject_properties,
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first_inobject_offset);
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}
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// Takes an index as computed by GetLoadByFieldIndex and reconstructs a
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// FieldIndex object from it.
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inline FieldIndex FieldIndex::ForLoadByFieldIndex(const Map* map,
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int orig_index) {
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int field_index = orig_index;
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bool is_inobject = true;
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int first_inobject_offset = 0;
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Encoding encoding = field_index & 1 ? kDouble : kTagged;
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field_index >>= 1;
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int offset;
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if (field_index < 0) {
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first_inobject_offset = FixedArray::kHeaderSize;
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field_index = -(field_index + 1);
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is_inobject = false;
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offset = FixedArray::kHeaderSize + field_index * kPointerSize;
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} else {
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first_inobject_offset = map->GetInObjectPropertyOffset(0);
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offset = map->GetInObjectPropertyOffset(field_index);
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}
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FieldIndex result(is_inobject, offset, encoding, map->GetInObjectProperties(),
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first_inobject_offset);
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DCHECK_EQ(result.GetLoadByFieldIndex(), orig_index);
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return result;
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}
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// Returns the index format accepted by the HLoadFieldByIndex instruction.
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// (In-object: zero-based from (object start + JSObject::kHeaderSize),
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// out-of-object: zero-based from FixedArray::kHeaderSize.)
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inline int FieldIndex::GetLoadByFieldIndex() const {
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// For efficiency, the LoadByFieldIndex instruction takes an index that is
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// optimized for quick access. If the property is inline, the index is
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// positive. If it's out-of-line, the encoded index is -raw_index - 1 to
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// disambiguate the zero out-of-line index from the zero inobject case.
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// The index itself is shifted up by one bit, the lower-most bit
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// signifying if the field is a mutable double box (1) or not (0).
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int result = index();
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if (is_inobject()) {
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result -= JSObject::kHeaderSize / kPointerSize;
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} else {
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result -= FixedArray::kHeaderSize / kPointerSize;
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result = -result - 1;
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}
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result <<= 1;
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return is_double() ? (result | 1) : result;
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}
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inline FieldIndex FieldIndex::ForDescriptor(const Map* map,
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int descriptor_index) {
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PropertyDetails details =
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map->instance_descriptors()->GetDetails(descriptor_index);
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int field_index = details.field_index();
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return ForPropertyIndex(map, field_index, details.representation());
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}
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} // namespace internal
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} // namespace v8
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#endif
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