tailrecursion-5.c

用于进行gcc测试

/* { dg-do run } */
/* { dg-options "-O1 -foptimize-sibling-calls -fdump-tree-optimized" } */

extern void abort (void);
extern void exit (int);

int sum (int n)
{
  if (n == 0)
    return 0;

  return n + sum (n - 1);
}

int fac (int n)
{
  if (n == 0)
    return 1;

  return n * fac (n - 1);
}

int sq_sum (int n)
{
  if (n == 0)
    return 0;

  return n * n + sq_sum (n - 1);
}

int pow2m1 (int n)
{
  if (n == 0)
    return 0;

  return 2 * pow2m1 (n - 1) + 1;
}

int fib (int n)
{
  if (n <= 1)
    return 1;

  return fib (n - 2) + fib (n - 1);
}

int main(void)
{
  if (sum (5) != 15)
    abort ();

  if (fac (5) != 120)
    abort ();

  if (sq_sum (5) != 55)
    abort ();

  if (pow2m1 (5) != 31)
    abort ();

  if (fib (5) != 8)
    abort ();

  exit (0);
}

/* There is one call of sum in main and then 2 instances of the word in
   ;; Function sum (sum) and one in the function header.  */
/* { dg-final { scan-tree-dump-times "\\msum\\M" 4 "optimized"} } */
/* { dg-final { scan-tree-dump-times "\\mfac\\M" 4 "optimized"} } */
/* { dg-final { scan-tree-dump-times "\\msq_sum\\M" 4 "optimized"} } */
/* { dg-final { scan-tree-dump-times "\\mpow2m1\\M" 4 "optimized"} } */

/* There is one recursive call to fib.  */
/* { dg-final { scan-tree-dump-times "\\mfib\\M" 5 "optimized"} } */

/* { dg-final { cleanup-tree-dump "optimized" } } */