727e808fb2
With only 2GB reservation we can make sure that the heap allocated in such a way, that all the pointer to it have the most significant bit in the low halfword set. This allows us to quickly distinguish between normal pointers and nullptr/sentinel when performing sign-extension inside decompression. Bug: chromium:1325007 Change-Id: Ie3a653796bb9dc875ec50103e05cb9aaf55515cf Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3793614 Reviewed-by: Michael Lippautz <mlippautz@chromium.org> Commit-Queue: Anton Bikineev <bikineev@chromium.org> Cr-Commit-Position: refs/heads/main@{#82310}
65 lines
1.9 KiB
C++
65 lines
1.9 KiB
C++
// 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 INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_
|
|
#define INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_
|
|
|
|
#include <cstddef>
|
|
#include <cstdint>
|
|
|
|
#include "v8config.h" // NOLINT(build/include_directory)
|
|
|
|
namespace cppgc {
|
|
namespace internal {
|
|
|
|
// Embedders should not rely on this code!
|
|
|
|
// Internal constants to avoid exposing internal types on the API surface.
|
|
namespace api_constants {
|
|
|
|
constexpr size_t kKB = 1024;
|
|
constexpr size_t kMB = kKB * 1024;
|
|
constexpr size_t kGB = kMB * 1024;
|
|
|
|
// Offset of the uint16_t bitfield from the payload contaning the
|
|
// in-construction bit. This is subtracted from the payload pointer to get
|
|
// to the right bitfield.
|
|
static constexpr size_t kFullyConstructedBitFieldOffsetFromPayload =
|
|
2 * sizeof(uint16_t);
|
|
// Mask for in-construction bit.
|
|
static constexpr uint16_t kFullyConstructedBitMask = uint16_t{1};
|
|
|
|
static constexpr size_t kPageSize = size_t{1} << 17;
|
|
|
|
#if defined(V8_TARGET_ARCH_ARM64) && defined(V8_OS_MACOS)
|
|
constexpr size_t kGuardPageSize = 0;
|
|
#else
|
|
constexpr size_t kGuardPageSize = 4096;
|
|
#endif
|
|
|
|
static constexpr size_t kLargeObjectSizeThreshold = kPageSize / 2;
|
|
|
|
#if defined(CPPGC_CAGED_HEAP)
|
|
constexpr size_t kCagedHeapReservationSize = static_cast<size_t>(2) * kGB;
|
|
constexpr size_t kCagedHeapReservationAlignment = kCagedHeapReservationSize;
|
|
|
|
constexpr size_t kCagedHeapNormalPageReservationSize =
|
|
kCagedHeapReservationSize / 2;
|
|
#endif
|
|
|
|
static constexpr size_t kDefaultAlignment = sizeof(void*);
|
|
|
|
// Maximum support alignment for a type as in `alignof(T)`.
|
|
static constexpr size_t kMaxSupportedAlignment = 2 * kDefaultAlignment;
|
|
|
|
// Granularity of heap allocations.
|
|
constexpr size_t kAllocationGranularity = sizeof(void*);
|
|
|
|
} // namespace api_constants
|
|
|
|
} // namespace internal
|
|
} // namespace cppgc
|
|
|
|
#endif // INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_
|