Test whether program compiled with tail call optimization.

gistfile1.c

#include <stdio.h>

/*
 * In a separate compilation unit, save is defined as:
 *
 *     void save(int *p)
 *     {
 *         *p = (int)&p;
 *     }
 */
extern void save(int *);

void recurse(int n, int *p)
{
    if (n == 0)
	return;
    save(p);
    recurse(n - 1, p + 1);
}

int is_tail_recursive(void)
{
    int a[2];
    recurse(2, a);
    return a[0] == a[1];
}

int main(int argc, char *argv[])
{
    if (is_tail_recursive()) {
	printf("tail recursive\n");
	while (1)
	    continue;
    }
    else
	printf("not tail recursive\n");
    return 0;
}