globals.h 2.06 KB
Newer Older
1 2 3 4 5 6 7 8 9 10
// Copyright 2020 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_HEAP_CPPGC_GLOBALS_H_
#define V8_HEAP_CPPGC_GLOBALS_H_

#include <stddef.h>
#include <stdint.h>

11
#include "include/cppgc/internal/gc-info.h"
12
#include "src/base/build_config.h"
13

14 15 16 17 18 19
namespace cppgc {
namespace internal {

using Address = uint8_t*;
using ConstAddress = const uint8_t*;

20 21 22 23
constexpr size_t kKB = 1024;
constexpr size_t kMB = kKB * 1024;
constexpr size_t kGB = kMB * 1024;

24 25 26
// AccessMode used for choosing between atomic and non-atomic accesses.
enum class AccessMode : uint8_t { kNonAtomic, kAtomic };

27 28 29 30 31 32 33
// See 6.7.6 (http://eel.is/c++draft/basic.align) for alignment restrictions. We
// do not fully support all alignment restrictions (following
// alignof(std​::​max_­align_­t)) but limit to alignof(double).
//
// This means that any scalar type with stricter alignment requirements (in
// practice: long double) cannot be used unrestricted in garbage-collected
// objects.
34
#if defined(V8_TARGET_ARCH_64_BIT)
35
constexpr size_t kAllocationGranularity = 8;
36 37 38
#else   // !V8_TARGET_ARCH_64_BIT
constexpr size_t kAllocationGranularity = 4;
#endif  // !V8_TARGET_ARCH_64_BIT
39 40
constexpr size_t kAllocationMask = kAllocationGranularity - 1;

41 42 43 44 45
constexpr size_t kPageSizeLog2 = 17;
constexpr size_t kPageSize = 1 << kPageSizeLog2;
constexpr size_t kPageOffsetMask = kPageSize - 1;
constexpr size_t kPageBaseMask = ~kPageOffsetMask;

46 47 48 49
// Guard pages are always put into memory. Whether they are actually protected
// depends on the allocator provided to the garbage collector.
constexpr size_t kGuardPageSize = 4096;

50 51
constexpr size_t kLargeObjectSizeThreshold = kPageSize / 2;

52 53 54
constexpr GCInfoIndex kFreeListGCInfoIndex = 0;
constexpr size_t kFreeListEntrySize = 2 * sizeof(uintptr_t);

55 56 57
constexpr size_t kCagedHeapReservationSize = static_cast<size_t>(4) * kGB;
constexpr size_t kCagedHeapReservationAlignment = kCagedHeapReservationSize;

58 59 60 61
}  // namespace internal
}  // namespace cppgc

#endif  // V8_HEAP_CPPGC_GLOBALS_H_