ccan

Browse Source Download (without any required ccan dependencies)

Module:

compiler

Summary:

macros for common compiler extensions

Author:

Rusty Russell <rusty@rustcorp.com.au>

Description:

Abstracts away some compiler hints. Currently these include: - COLD

     For functions not called in fast paths (aka. cold functions)

- PRINTF_FMT

     For functions which take printf-style parameters.

- CONST_FUNCTION

     For functions which return the same value for same parameters.

- NEEDED

     For functions and variables which must be emitted even if unused.

- UNNEEDED

     For functions and variables which need not be emitted if unused.

- UNUSED

     For parameters which are not used.

- IS_COMPILE_CONSTANT()

     For using different tradeoffs for compiletime vs runtime evaluation.

Example:

#include <ccan/compiler/compiler.h>
#include <stdio.h>
#include <stdarg.h>

// Example of a (slow-path) logging function.
static int log_threshold = 2;
static void COLD PRINTF_FMT(2,3)
        logger(int level, const char *fmt, ...)
{
        va_list ap;
        va_start(ap, fmt);
        if (level >= log_threshold)
                vfprintf(stderr, fmt, ap);
        va_end(ap);
}

int main(int argc, char *argv[])
{
        if (argc != 1) {
                logger(3, "Don't want %i arguments!\n", argc-1);
                return 1;
        }
        return 0;
}

License: