[Bug rtl-optimization/48702] optimization regression with gcc-4.6 on x86_64-unknown-linux-gnu

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48702

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011.04.20 14:28:27
      Known to work|                            |4.7.0
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-04-20 
14:28:27 UTC ---
Confirmed.  Seems to work on trunk.

The following fails at -O1:

extern void abort (void);

#define LEN 4

static inline void unpack(int  array[LEN])
{
  int ii, val;
  val = 1;
  for (ii = 0; ii < LEN; ii++) {
      array[ii] = val % 2;
      val = val / 2;
  }
}

static inline int  pack(int  array[LEN])
{
  int ans, ii;
  ans = 0;
  for (ii = LEN-1; ii >= 0; ii--) {
      ans = 2 * ans + array[ii];
  }
  return ans;
}

int __attribute__((noinline))
foo()
{
  int temp, ans;
  int array[LEN];
  unpack(array);
  temp = array[0];
  array[0] = array[2];
  array[2] = temp;
  ans = pack(array);
  return ans;
}

int main(void)
{
  int val;
  val = foo();
  if (val != 4)
    abort ();
  return 0;
}