c++内存分析：ASan

AddressSanitizer（ASan）是一款广泛使用的c++内存分析工具，能够检测代码中的各种内存问题（内存越界、访问野指针、非法访问栈内存等等很多）

唯独不能分析内存泄漏问题，内存泄漏问题可以用另外一款名为LeakSanitizer（LSan）的工具检测

vs 2022 内置了对ASan的支持，参考https://learn.microsoft.com/zh-cn/cpp/sanitizers/asan?view=msvc-170

如何在vs中配置ASan

0. 安装

使用vs installer安装ASan支持

1. Enable AddressSanitizer(ASan)

Configuration Properties > C/C++ > General, then modify the Enable AddressSanitizer property. Choose OK to save your changes.

2. 触发内存问题后生成dump

添加环境变量：set ASAN_SAVE_DUMPS=MyFileName.dmp

参考https://learn.microsoft.com/zh-cn/cpp/sanitizers/asan-debugger-integration?view=msvc-170

3. Continue on error

参考https://learn.microsoft.com/zh-cn/cpp/sanitizers/asan-continue-on-error?view=msvc-170

默认是触发了内存问题后直接抛异常然后crash，开启这个选项以后可以让程序继续执行，等程序结束后统一输出错误报告

添加环境变量：set ASAN_OPTIONS=continue_on_error=1

使用 ASAN_OPTIONS 环境变量确定将 ASAN 输出发送到何处，如下所示： - 输出到 stdout：set ASAN_OPTIONS = continue_on_error = 1 - 输出到 stderr：set ASAN_OPTIONS = continue_on_error = 2 - 输出到所选日志文件：set COE_LOG_FILE = yourfile.log

4. 启用分配和释放不匹配检测

这个并不是检测内存泄漏，主要是检测 new/free，malloc/delete 这样的不匹配问题

默认不开启

添加环境变量：set ASAN_OPTIONS = alloc_dealloc_mismatch = 1

5. ASAN_OPTIONS的多个选项之间用冒号分隔

例如：set ASAN_OPTIONS=continue_on_error=1:alloc_dealloc_mismatch=1

Debug模式或`/Od`优化模式下需要的额外配置

Turn off edit and continue

Open Tools > Options > Debugging > .NET / C++ Hot Reload.

Turn off both of the following options to enable Edit and Continue. - Enable Hot Reload and Edit and Continue when debugging. - Enable Hot Reload when starting without debugging

Turn off /RTC1

Configuration Properties > C / C++ > Code Generation property page.

Turn off one or both of the following properties : Basic Runtime Checks or Smaller Type Check.

Turn off Incremental Link

Select the Configuration Properties > Linker > General property page.

Modify the Enable Incremental Linking property.

Trouble shooting

1. The code execution cannot proceed because clang_rt.asan_dynamic-x86_64.dll was not found.

参考https://devblogs.microsoft.com/cppblog/msvc-address-sanitizer-one-dll-for-all-runtime-configurations/

Please update the PATH to include clang_rt.asan_dynamic - x86_64.dll(x64) or clang_rt.asan_dynamic - i386.dll(x86).