1 files changed, 67 insertions, 0 deletions
diff --git a/chromium/v8/include/cppgc/internal/caged-heap-local-data.h b/chromium/v8/include/cppgc/internal/caged-heap-local-data.h
new file mode 100644
index 00000000000..8c421477384
--- /dev/null
+++ b/chromium/v8/include/cppgc/internal/caged-heap-local-data.h
@@ -0,0 +1,67 @@
+// 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_CAGED_HEAP_LOCAL_DATA_H_
+#define INCLUDE_CPPGC_INTERNAL_CAGED_HEAP_LOCAL_DATA_H_
+
+#include <array>
+
+#include "cppgc/internal/api-constants.h"
+#include "cppgc/internal/logging.h"
+#include "cppgc/platform.h"
+
+namespace cppgc {
+namespace internal {
+
+class HeapBase;
+
+#if defined(CPPGC_YOUNG_GENERATION)
+
+// AgeTable contains entries that correspond to 4KB memory regions. Each entry
+// can be in one of three states: kOld, kYoung or kUnknown.
+class AgeTable final {
+  static constexpr size_t kGranularityBits = 12;  // 4KiB per byte.
+
+ public:
+  enum class Age : uint8_t { kOld, kYoung, kUnknown };
+
+  static constexpr size_t kEntrySizeInBytes = 1 << kGranularityBits;
+
+  Age& operator[](uintptr_t offset) { return table_[entry(offset)]; }
+  Age operator[](uintptr_t offset) const { return table_[entry(offset)]; }
+
+  void Reset(PageAllocator* allocator);
+
+ private:
+  static constexpr size_t kAgeTableSize =
+      api_constants::kCagedHeapReservationSize >> kGranularityBits;
+
+  size_t entry(uintptr_t offset) const {
+    const size_t entry = offset >> kGranularityBits;
+    CPPGC_DCHECK(table_.size() > entry);
+    return entry;
+  }
+
+  std::array<Age, kAgeTableSize> table_;
+};
+
+static_assert(sizeof(AgeTable) == 1 * api_constants::kMB,
+              "Size of AgeTable is 1MB");
+
+#endif  // CPPGC_YOUNG_GENERATION
+
+struct CagedHeapLocalData final {
+  explicit CagedHeapLocalData(HeapBase* heap_base) : heap_base(heap_base) {}
+
+  bool is_marking_in_progress = false;
+  HeapBase* heap_base = nullptr;
+#if defined(CPPGC_YOUNG_GENERATION)
+  AgeTable age_table;
+#endif
+};
+
+}  // namespace internal
+}  // namespace cppgc
+
+#endif  // INCLUDE_CPPGC_INTERNAL_CAGED_HEAP_LOCAL_DATA_H_