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_CAGED_HEAP_LOCAL_DATA_H_ 6 #define INCLUDE_CPPGC_INTERNAL_CAGED_HEAP_LOCAL_DATA_H_ 7 8 #include <array> 9 #include <cstddef> 10 #include <cstdint> 11 12 #include "cppgc/internal/api-constants.h" 13 #include "cppgc/internal/logging.h" 14 #include "cppgc/platform.h" 15 #include "v8config.h" // NOLINT(build/include_directory) 16 17 namespace cppgc { 18 namespace internal { 19 20 class HeapBase; 21 22 #if defined(CPPGC_YOUNG_GENERATION) 23 24 // AgeTable is the bytemap needed for the fast generation check in the write 25 // barrier. AgeTable contains entries that correspond to 512 bytes memory 26 // regions (cards). Each entry in the table represents generation of the objects 27 // that reside on the corresponding card (young, old or mixed). 28 class AgeTable final { 29 static constexpr size_t kRequiredSize = 1 * api_constants::kMB; 30 static constexpr size_t kAllocationGranularity = 31 api_constants::kAllocationGranularity; 32 33 public: 34 enum class Age : uint8_t { kOld, kYoung, kMixed }; 35 36 static constexpr size_t kCardSizeInBytes = 37 (api_constants::kCagedHeapReservationSize / kAllocationGranularity) / 38 kRequiredSize; 39 SetAge(uintptr_t cage_offset,Age age)40 void SetAge(uintptr_t cage_offset, Age age) { 41 table_[card(cage_offset)] = age; 42 } GetAge(uintptr_t cage_offset)43 V8_INLINE Age GetAge(uintptr_t cage_offset) const { 44 return table_[card(cage_offset)]; 45 } 46 47 void Reset(PageAllocator* allocator); 48 49 private: card(uintptr_t offset)50 V8_INLINE size_t card(uintptr_t offset) const { 51 constexpr size_t kGranularityBits = 52 __builtin_ctz(static_cast<uint32_t>(kCardSizeInBytes)); 53 const size_t entry = offset >> kGranularityBits; 54 CPPGC_DCHECK(table_.size() > entry); 55 return entry; 56 } 57 58 std::array<Age, kRequiredSize> table_; 59 }; 60 61 static_assert(sizeof(AgeTable) == 1 * api_constants::kMB, 62 "Size of AgeTable is 1MB"); 63 64 #endif // CPPGC_YOUNG_GENERATION 65 66 struct CagedHeapLocalData final { 67 CagedHeapLocalData(HeapBase&, PageAllocator&); 68 69 bool is_incremental_marking_in_progress = false; 70 HeapBase& heap_base; 71 #if defined(CPPGC_YOUNG_GENERATION) 72 AgeTable age_table; 73 #endif 74 }; 75 76 } // namespace internal 77 } // namespace cppgc 78 79 #endif // INCLUDE_CPPGC_INTERNAL_CAGED_HEAP_LOCAL_DATA_H_ 80