[Bug middle-end/33992] [4.3 Regression] Miscompiles a function, breaks profiledbootstrap

[ubizjak at gmail dot com]

------- Comment #26 from ubizjak at gmail dot com  2008-02-10 08:23 -------
Following is significantly minimized testcase:

--cut here--
#include <stdlib.h>
#include <stdio.h>

struct real_value
{
  unsigned long sig[3];
};


#ifdef INLINE
static inline void __attribute__((always_inline))
#else
static void __attribute__((noinline))
#endif
normalize (struct real_value *r)

{
  int j;

  for (j = 0; ; j++)
    if (r->sig[2] & ((unsigned long)1 << (63 - j)))
      break;

  printf ("%i\n", j);

  if (j)
    abort ();
}

static void __attribute__((noinline))
  do_test (struct real_value *r)
{
  int i;

  for (i = 0; i < 2; ++i)
    normalize (r);
}

int main()
{
  struct real_value r;

  r.sig[0] = 0ull;
  r.sig[1] = 0ull;
  r.sig[2] = 0x8000000000000001ull;

  do_test (&r);

  return 0;
}
--cut here--

[uros@localhost test]$ gcc -O2 -DINLINE t1.c
[uros@localhost test]$ ./a.out
63
Aborted
[uros@localhost test]$ gcc -O2  t1.c
[uros@localhost test]$ ./a.out
0
0

Note, that it looks like MSB is not detected in normalize().


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33992