modernc.org/ccgo/v3@v3.16.14/lib/testdata/gcc-9.1.0/gcc/testsuite/gcc.c-torture/execute/builtin-constant.c (about)

     1  /* PR optimization/8423.  */
     2  
     3  #define btest(x) __builtin_constant_p(x) ? "1" : "0"
     4  
     5  #ifdef __OPTIMIZE__
     6  void
     7  foo (char *i)
     8  {
     9    if (*i == '0')
    10      abort ();
    11  }
    12  #else
    13  void
    14  foo (char *i)
    15  {
    16  }
    17  #endif
    18  
    19  int
    20  main (void)
    21  {
    22    int size = sizeof (int);
    23    foo (btest (size));
    24    foo (btest (size));
    25    exit (0);
    26  }