Why is `__gxx_personality_v0` Needed in C Compilation, and How Does it Relate to Exception Handling?

Unveiling the Purpose of __gxx_personality_v0

When compiling free-standing C programs with gcc, one may encounter a linker error related to the undefined symbol "__gxx_personality_v0." This symbol resides in libstdc , which is absent in free-standing environments. Adding the definition "void *__gxx_personality_v0;" resolves the issue, but understanding its purpose remains crucial.

__gxx_personality_v0 plays a pivotal role in stack unwinding tables. These tables are visible in assembly outputs and serve as the basis for exception handling. As defined by the Itanium C ABI, __gxx_personality_v0 functions as the Personality Routine, a critical component in exception unwinding.

The "magic" behind its resolution as a global NULL void pointer stems from the absence of exception throws. If an exception were to occur, the symbol's behavior would become apparent. To avoid such issues, disabling exceptions with "-fno-exceptions" or linking with g (which automatically adds "-lstdc ") becomes necessary when exceptions are employed.

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