[Bug middle-end/32244] bit-field: optimization BUG

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2008-01-25 13:23 -------
Uh, all is broken ;)

  1) we don't reduce shift or rotate results

  2) we do wrong folding of rotates

  3) we do wrong expansion of rotates

struct foo
{
  unsigned long long b:40;
} x;

extern void abort (void);

void test1(unsigned long long res)
{
  /* Build a rotate expression on a 40 bit argument.  */
  if ((x.b<<8) + (x.b>>32) != res)
    abort ();
}

int main()
{
  x.b = 0x0100000001;
  test1(0x0000000101);
  x.b = 0x0100000000;
  test1(0x0000000001);
  return 0;
}


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2007-06-08 10:28:26         |2008-01-25 13:23:02
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32244