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1// Copyright 2020 the V8 project authors. All rights reserved.2// Use of this source code is governed by a BSD-style license that can be3// found in the LICENSE file.4 5#ifndef INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_6#define INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_7 8#include <cstddef>9#include <cstdint>10 11#include "v8config.h"  // NOLINT(build/include_directory)12 13namespace cppgc {14namespace internal {15 16// Embedders should not rely on this code!17 18// Internal constants to avoid exposing internal types on the API surface.19namespace api_constants {20 21constexpr size_t kKB = 1024;22constexpr size_t kMB = kKB * 1024;23constexpr size_t kGB = kMB * 1024;24 25// Offset of the uint16_t bitfield from the payload contaning the26// in-construction bit. This is subtracted from the payload pointer to get27// to the right bitfield.28static constexpr size_t kFullyConstructedBitFieldOffsetFromPayload =29    2 * sizeof(uint16_t);30// Mask for in-construction bit.31static constexpr uint16_t kFullyConstructedBitMask = uint16_t{1};32 33static constexpr size_t kPageSizeBits = 17;34static constexpr size_t kPageSize = size_t{1} << kPageSizeBits;35 36static constexpr size_t kLargeObjectSizeThreshold = kPageSize / 2;37 38#if defined(CPPGC_POINTER_COMPRESSION)39#if defined(CPPGC_ENABLE_LARGER_CAGE)40constexpr unsigned kPointerCompressionShift = 3;41#else   // !defined(CPPGC_ENABLE_LARGER_CAGE)42constexpr unsigned kPointerCompressionShift = 1;43#endif  // !defined(CPPGC_ENABLE_LARGER_CAGE)44#endif  // !defined(CPPGC_POINTER_COMPRESSION)45 46#if defined(CPPGC_CAGED_HEAP)47constexpr size_t kCagedHeapDefaultReservationSize =48    static_cast<size_t>(4) * kGB;49#if defined(CPPGC_POINTER_COMPRESSION)50constexpr size_t kCagedHeapMaxReservationSize =51    size_t{1} << (31 + kPointerCompressionShift);52#else   // !defined(CPPGC_POINTER_COMPRESSION)53constexpr size_t kCagedHeapMaxReservationSize =54    kCagedHeapDefaultReservationSize;55#endif  // !defined(CPPGC_POINTER_COMPRESSION)56constexpr size_t kCagedHeapReservationAlignment = kCagedHeapMaxReservationSize;57#endif  // defined(CPPGC_CAGED_HEAP)58 59static constexpr size_t kDefaultAlignment = sizeof(void*);60 61// Maximum support alignment for a type as in `alignof(T)`.62static constexpr size_t kMaxSupportedAlignment = 2 * kDefaultAlignment;63 64// Granularity of heap allocations.65constexpr size_t kAllocationGranularity = sizeof(void*);66 67// Default cacheline size.68constexpr size_t kCachelineSize = 64;69 70}  // namespace api_constants71 72}  // namespace internal73}  // namespace cppgc74 75#endif  // INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_76