modernc.org/ccgo/v3@v3.16.14/lib/testdata/gcc-9.1.0/gcc/testsuite/gcc.c-torture/execute/pr82524.c (about)

     1  /* PR target/82524 */
     2  
     3  struct S { unsigned char b, g, r, a; };
     4  union U { struct S c; unsigned v; };
     5  
     6  static inline unsigned char
     7  foo (unsigned char a, unsigned char b)
     8  {
     9    return ((a + 1) * b) >> 8;
    10  }
    11  
    12  __attribute__((noinline, noclone)) unsigned
    13  bar (union U *x, union U *y)
    14  {
    15    union U z;
    16    unsigned char v = x->c.a;
    17    unsigned char w = foo (y->c.a, 255 - v);
    18    z.c.r = foo (x->c.r, v) + foo (y->c.r, w);
    19    z.c.g = foo (x->c.g, v) + foo (y->c.g, w);
    20    z.c.b = foo (x->c.b, v) + foo (y->c.b, w);
    21    z.c.a = 0;
    22    return z.v;
    23  }
    24  
    25  int
    26  main ()
    27  {
    28    union U a, b, c;
    29    if ((unsigned char) ~0 != 255 || sizeof (unsigned) != 4)
    30      return 0;
    31    a.c = (struct S) { 255, 255, 255, 0 };
    32    b.c = (struct S) { 255, 255, 255, 255 };
    33    c.v = bar (&a, &b);
    34    if (c.c.b != 255 || c.c.g != 255 || c.c.r != 255 || c.c.a != 0)
    35      __builtin_abort ();
    36    return 0;
    37  }