Support for builtin functions

[Johann Peter]

Hi,

does cppcheck support builtin functions?

Under gcc I tried:

    uint8_t test[10];
    __builtin_memset(test,0x00,1000); //no error
    memset(test,0x00,1000); //error

The builtin memset does not show as an error.

If this is not a bug but a feature, can I implement the same checks for builtin functions via library .cfg files?

Best regards,
Johann

[orbitcowboy]

Are you referring to GNU builtin functions?
If yes, we could extend our gnu.cfg file about these definitions. The corresponding file is available here: https://github.com/danmar/cppcheck/blob/master/cfg/gnu.cfg

[orbitcowboy]

Experimental support for __builtin_memset has been added with https://github.com/danmar/cppcheck/commit/b998dcb5aaf76b0eba74fa2ae3c4fa081c75ca68
Scanning following example

int main()
{
    uint8_t buf[42];
    __builtin_memset(buf,0,1000);
}

gives now
(error) Buffer is accessed out of bounds: buf

[Daniel Marjamäki]

yes it is possible by cfg file updates.
I am curious, why do you encounter builtin_memset? I assume you include system headers and your code is corrupted by macros?

[Johann Peter]

We have an embedded STM32 project (AC6 toolchain). We are fixed on the compiler version and the optimisation lvl. Using gcc builtins gives us a performance boost because the compiler replaces (if possible) the function call with just some ASM instructions. We use the whole bandwith of builtin functions, including stuff like __builtin_ tolower, strlen, memcmp, memcpy etc.

[orbitcowboy]

Are you intetested providing a Pull Request to support these builtin functions?