Compiler attributes

#include <libcork/core.h>

The macros in this section define compiler-agnostic versions of several common compiler attributes.

CORK_LIKELY(expression)

CORK_UNLIKELY(expression)

Indicate that the given Boolean expression is likely to be true or false, respectively. The compiler can sometimes use this information to generate more efficient code.

CORK_ATTR_CONST

Declare a “constant” function. The return value of a constant function can only depend on its parameters. This is slightly more strict than a “pure” function (declared by CORK_ATTR_PURE); a constant function is not allowed to read from global variables, whereas a pure function is.

Note

Note that the compiler won’t verify that your function meets the requirements of a constant function. Instead, this attribute notifies the compiler of your intentions, which allows the compiler to assume more about your function when optimizing code that calls it.

int square(int x) CORK_ATTR_CONST;

CORK_ATTR_MALLOC

Declare a function that returns a newly allocated pointer. The compiler can use this information to generate more accurate aliasing information, since it can infer that the result of the function cannot alias any other existing pointer.

void *custom_malloc(size_t size) CORK_ATTR_MALLOC;

CORK_ATTR_NOINLINE

Declare that a function shouldn’t be eligible for inlining.

CORK_ATTR_PRINTF(format_index, args_index)

Declare a function that takes in printf-like parameters. format_index is the index (starting from 1) of the parameter that contains the printf format string. args_index is the index of the first parameter that contains the data to format.

CORK_ATTR_PURE

Declare a “pure” function. The return value of a pure function can only depend on its parameters, and on global variables.

static int  _next_id;
int get_next_id(void) CORK_ATTR_PURE;

CORK_ATTR_SENTINEL

Declare a var-arg function whose last parameter must be a NULL sentinel value. When the compiler supports this attribute, it will check the actual parameters whenever this function is called, and ensure that the last parameter is a NULL.

CORK_ATTR_UNUSED

Declare a entity that might not be used. This lets you keep -Wall activated in several cases where you’re obligated to define something that you don’t intend to use.

CORK_ATTR_UNUSED static void
unused_function(void)
{
    CORK_ATTR_UNUSED int  unused_value;
}

CORK_INITIALIZER(func_name)

Declare a static function that will be automatically called at program startup. If there are multiple initializer functions linked into a program, there is no guarantee about the order in which the functions will be called.

#include <libcork/core.h>
#include <libcork/ds.h>

static cork_array(int)  array;

CORK_INITIALIZER(init_array)
{
   cork_array_init(&array);
}