cppgc/internal/caged-heap.h

0001 // Copyright 2022 the V8 project authors. All rights reserved.
0002 // Use of this source code is governed by a BSD-style license that can be
0003 // found in the LICENSE file.
0004
0005 #ifndef INCLUDE_CPPGC_INTERNAL_CAGED_HEAP_H_
0006 #define INCLUDE_CPPGC_INTERNAL_CAGED_HEAP_H_
0007
0008 #include <climits>
0009 #include <cstddef>
0010
0011 #include "cppgc/internal/api-constants.h"
0012 #include "cppgc/internal/base-page-handle.h"
0013 #include "v8config.h"  // NOLINT(build/include_directory)
0014
0015 #if defined(CPPGC_CAGED_HEAP)
0016
0017 namespace cppgc {
0018 namespace internal {
0019
0020 class V8_EXPORT CagedHeapBase {
0021  public:
0022   V8_INLINE static uintptr_t OffsetFromAddress(const void* address) {
0023     return reinterpret_cast<uintptr_t>(address) &
0024            (api_constants::kCagedHeapReservationAlignment - 1);
0025   }
0026
0027   V8_INLINE static bool IsWithinCage(const void* address) {
0028     CPPGC_DCHECK(g_heap_base_);
0029     return (reinterpret_cast<uintptr_t>(address) &
0030             ~(api_constants::kCagedHeapReservationAlignment - 1)) ==
0031            g_heap_base_;
0032   }
0033
0034   V8_INLINE static bool AreWithinCage(const void* addr1, const void* addr2) {
0035 #if defined(CPPGC_2GB_CAGE)
0036     static constexpr size_t kHeapBaseShift = sizeof(uint32_t) * CHAR_BIT - 1;
0037 #else   //! defined(CPPGC_2GB_CAGE)
0038 #if defined(CPPGC_POINTER_COMPRESSION)
0039     static constexpr size_t kHeapBaseShift =
0040         31 + api_constants::kPointerCompressionShift;
0041 #else   // !defined(CPPGC_POINTER_COMPRESSION)
0042     static constexpr size_t kHeapBaseShift = sizeof(uint32_t) * CHAR_BIT;
0043 #endif  // !defined(CPPGC_POINTER_COMPRESSION)
0044 #endif  //! defined(CPPGC_2GB_CAGE)
0045     static_assert((static_cast<size_t>(1) << kHeapBaseShift) ==
0046                   api_constants::kCagedHeapMaxReservationSize);
0047     CPPGC_DCHECK(g_heap_base_);
0048     return !(((reinterpret_cast<uintptr_t>(addr1) ^ g_heap_base_) |
0049               (reinterpret_cast<uintptr_t>(addr2) ^ g_heap_base_)) >>
0050              kHeapBaseShift);
0051   }
0052
0053   V8_INLINE static uintptr_t GetBase() { return g_heap_base_; }
0054   V8_INLINE static size_t GetAgeTableSize() { return g_age_table_size_; }
0055
0056  private:
0057   friend class CagedHeap;
0058
0059   static uintptr_t g_heap_base_;
0060   static size_t g_age_table_size_;
0061 };
0062
0063 }  // namespace internal
0064 }  // namespace cppgc
0065
0066 #endif  // defined(CPPGC_CAGED_HEAP)
0067
0068 #endif  // INCLUDE_CPPGC_INTERNAL_CAGED_HEAP_H_