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 13 namespace cppgc { 14 namespace internal { 15 16 // Embedders should not rely on this code! 17 18 // Internal constants to avoid exposing internal types on the API surface. 19 namespace api_constants { 20 21 constexpr size_t kKB = 1024; 22 constexpr size_t kMB = kKB * 1024; 23 constexpr 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. 28 static constexpr size_t kFullyConstructedBitFieldOffsetFromPayload = 29 2 * sizeof(uint16_t); 30 // Mask for in-construction bit. 31 static constexpr uint16_t kFullyConstructedBitMask = uint16_t{1}; 32 33 static constexpr size_t kPageSize = size_t{1} << 17; 34 35 static constexpr size_t kLargeObjectSizeThreshold = kPageSize / 2; 36 37 #if defined(CPPGC_CAGED_HEAP) 38 constexpr size_t kCagedHeapReservationSize = static_cast<size_t>(4) * kGB; 39 constexpr size_t kCagedHeapReservationAlignment = kCagedHeapReservationSize; 40 #endif 41 42 static constexpr size_t kDefaultAlignment = sizeof(void*); 43 44 // Maximum support alignment for a type as in `alignof(T)`. 45 static constexpr size_t kMaxSupportedAlignment = 2 * kDefaultAlignment; 46 47 // Granularity of heap allocations. 48 constexpr size_t kAllocationGranularity = sizeof(void*); 49 50 } // namespace api_constants 51 52 } // namespace internal 53 } // namespace cppgc 54 55 #endif // INCLUDE_CPPGC_INTERNAL_API_CONSTANTS_H_ 56