Michael Lippautz
6d7526671e
The GCInfoIndex is always written on allocation. This does not affect writing/reading the construction bit which happens with a mask. This safes one shift in the allocation fast path (for GCInfoIndex). Drive-by: Use std::atomic_ref instead of casts to std::atomic. Change-Id: I8932f46ef582558d30eded9bab9b8d210a0ee1cb Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7213182 Auto-Submit: Michael Lippautz <mlippautz@chromium.org> Commit-Queue: Michael Lippautz <mlippautz@chromium.org> Reviewed-by: Omer Katz <omerkatz@chromium.org> Cr-Commit-Position: refs/heads/main@{#104077}
76 lines
2.5 KiB
C++
76 lines
2.5 KiB
C++
// Copyright 2020 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 INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_
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#define INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_
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#include <cstddef>
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#include <cstdint>
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#include "v8config.h" // NOLINT(build/include_directory)
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namespace cppgc {
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namespace internal {
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// Embedders should not rely on this code!
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// Internal constants to avoid exposing internal types on the API surface.
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namespace api_constants {
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constexpr size_t kKB = 1024;
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constexpr size_t kMB = kKB * 1024;
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constexpr size_t kGB = kMB * 1024;
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// Offset of the uint16_t bitfield from the payload contaning the
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// in-construction bit. This is subtracted from the payload pointer to get
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// to the right bitfield.
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static constexpr size_t kFullyConstructedBitFieldOffsetFromPayload =
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2 * sizeof(uint16_t);
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// Mask for in-construction bit.
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static constexpr uint16_t kFullyConstructedBitMask = uint16_t{1} << 15;
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static constexpr size_t kPageSizeBits = 17;
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static constexpr size_t kPageSize = size_t{1} << kPageSizeBits;
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static constexpr size_t kLargeObjectSizeThreshold = kPageSize / 2;
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#if defined(CPPGC_POINTER_COMPRESSION)
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#if defined(CPPGC_ENABLE_LARGER_CAGE)
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constexpr unsigned kPointerCompressionShift = 3;
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#else // !defined(CPPGC_ENABLE_LARGER_CAGE)
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constexpr unsigned kPointerCompressionShift = 1;
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#endif // !defined(CPPGC_ENABLE_LARGER_CAGE)
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#endif // !defined(CPPGC_POINTER_COMPRESSION)
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#if defined(CPPGC_CAGED_HEAP)
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constexpr size_t kCagedHeapDefaultReservationSize =
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static_cast<size_t>(4) * kGB;
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#if defined(CPPGC_POINTER_COMPRESSION)
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constexpr size_t kCagedHeapMaxReservationSize =
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size_t{1} << (31 + kPointerCompressionShift);
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#else // !defined(CPPGC_POINTER_COMPRESSION)
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constexpr size_t kCagedHeapMaxReservationSize =
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kCagedHeapDefaultReservationSize;
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#endif // !defined(CPPGC_POINTER_COMPRESSION)
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constexpr size_t kCagedHeapReservationAlignment = kCagedHeapMaxReservationSize;
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#endif // defined(CPPGC_CAGED_HEAP)
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static constexpr size_t kDefaultAlignment = sizeof(void*);
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// Maximum support alignment for a type as in `alignof(T)`.
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static constexpr size_t kMaxSupportedAlignment = 2 * kDefaultAlignment;
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// Granularity of heap allocations.
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constexpr size_t kAllocationGranularity = sizeof(void*);
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// Default cacheline size.
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constexpr size_t kCachelineSize = 64;
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} // namespace api_constants
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} // namespace internal
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} // namespace cppgc
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#endif // INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_
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