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 be
3// 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 the
26// in-construction bit. This is subtracted from the payload pointer to get
27// 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 kPageSize = size_t{1} << 17;
34
35#if defined(V8_TARGET_ARCH_ARM64) && defined(V8_OS_DARWIN)
36constexpr size_t kGuardPageSize = 0;
37#else
38constexpr size_t kGuardPageSize = 4096;
39#endif
40
41static constexpr size_t kLargeObjectSizeThreshold = kPageSize / 2;
42
43#if defined(CPPGC_CAGED_HEAP)
44#if defined(CPPGC_2GB_CAGE)
45constexpr size_t kCagedHeapReservationSize = static_cast<size_t>(2) * kGB;
46#else   // !defined(CPPGC_2GB_CAGE)
47constexpr size_t kCagedHeapReservationSize = static_cast<size_t>(4) * kGB;
48#endif  // !defined(CPPGC_2GB_CAGE)
49constexpr size_t kCagedHeapReservationAlignment = kCagedHeapReservationSize;
50#endif  // defined(CPPGC_CAGED_HEAP)
51
52static constexpr size_t kDefaultAlignment = sizeof(void*);
53
54// Maximum support alignment for a type as in `alignof(T)`.
55static constexpr size_t kMaxSupportedAlignment = 2 * kDefaultAlignment;
56
57// Granularity of heap allocations.
58constexpr size_t kAllocationGranularity = sizeof(void*);
59
60// Default cacheline size.
61constexpr size_t kCachelineSize = 64;
62
63}  // namespace api_constants
64
65}  // namespace internal
66}  // namespace cppgc
67
68#endif  // INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_
69