memory.h

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// Copyright 2021 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 V8_HEAP_CPPGC_MEMORY_H_
#define V8_HEAP_CPPGC_MEMORY_H_
 
#include <cstddef>
#include <cstdint>
#include <cstring>
 
#include "src/base/macros.h"
#include "src/base/sanitizer/asan.h"
#include "src/base/sanitizer/msan.h"
#include "src/heap/cppgc/globals.h"
 
namespace cppgc {
namespace internal {
 
V8_NOINLINE DISABLE_ASAN void NoSanitizeMemset(void* address, char c,
                                               size_t bytes);
 
static constexpr uint8_t kZappedValue = 0xdc;
 
V8_INLINE void ZapMemory(void* address, size_t size) {
  // The lowest bit of the zapped value should be 0 so that zapped object are
  // never viewed as fully constructed objects.
  memset(address, kZappedValue, size);
}
 
V8_INLINE void CheckMemoryIsZapped(const void* address, size_t size) {
  for (size_t i = 0; i < size; i++) {
    CHECK_EQ(kZappedValue, reinterpret_cast<ConstAddress>(address)[i]);
  }
}
 
V8_INLINE void CheckMemoryIsZero(const void* address, size_t size) {
  for (size_t i = 0; i < size; i++) {
    CHECK_EQ(0, reinterpret_cast<ConstAddress>(address)[i]);
  }
}
 
// Together `SetMemoryAccessible()` and `SetMemoryInaccessible()` form the
// memory access model for allocation and free.
 
#if defined(V8_USE_MEMORY_SANITIZER) || defined(V8_USE_ADDRESS_SANITIZER) || \
    DEBUG
 
void SetMemoryAccessible(void* address, size_t size);
void SetMemoryInaccessible(void* address, size_t size);
void CheckMemoryIsInaccessible(const void* address, size_t size);
 
constexpr bool CheckMemoryIsInaccessibleIsNoop() {
#if defined(V8_USE_MEMORY_SANITIZER)
 
  return true;
 
#elif defined(V8_USE_ADDRESS_SANITIZER)
 
  return false;
 
#else  // Debug builds.
 
  return false;
 
#endif  // Debug builds.
}
 
#else
 
// Nothing to be done for release builds.
V8_INLINE void SetMemoryAccessible(void* address, size_t size) {}
V8_INLINE void CheckMemoryIsInaccessible(const void* address, size_t size) {}
constexpr bool CheckMemoryIsInaccessibleIsNoop() { return true; }
 
V8_INLINE void SetMemoryInaccessible(void* address, size_t size) {
  memset(address, 0, size);
}
 
#endif
 
}  // namespace internal
}  // namespace cppgc
 
#endif  // V8_HEAP_CPPGC_MEMORY_H_