C/C++ Instrumentation#

Prerequisites#

Instrumentation for C and C++ is packaged with the C++ SDK. Instrumentation is supported by the header file antithesis_instrumentation.h. This file must be included in one, and only one translation unit at link time. Coverage instrumentation requires Clang 13 or higher, and either C++ 11 or higher or C89 or higher.

We recommended that you include the instrumentation header in the file where you define the main function, as follows:

#include "antithesis_instrumentation.h"

Note

If you are unable to meet the requirements of our C/C++ instrumentation, perhaps because you use an older version of Clang or are unable to include a header file, then you can try our legacy instrumentation approach. This approach does not require a modern Clang or a header file, but it will instead require you to provide a shared object at link-time.

Build Requirements#

Add the following compile flag:

-fsanitize-coverage=trace-pc-guard -g

And add the following link flag:

--build-id

If your build process includes a single compile/link step, then add both compile and link flags with the following:

-fsanitize-coverage=trace-pc-guard -g -Wl,--build-id

Note

We recommend the use of -g but it is not necessary. It will provide more detailed information when bugs are found, which may make debugging easier.

Validation#

To confirm that the instrumentation process was successful, you can run the command nm to list all the symbols in a binary, and then grep the string “antithesis_load_libvoidstar” .

$ nm client_binary | grep "antithesis_load_libvoidstar"
T antithesis_load_libvoidstar

Notice the “T” character in the previous code block: it means the symbol is in the text (code) section.

If this does not work you probably failed to include the header file.

Symbolization#

The LLVM compiler infrastructure will output debug symbols in the DWARF format. They could be separate debug info or just the original unstripped binary. These files should be symlinked (or moved) into a directory named /symbols in the root of the appropriate container image.