[Bug tree-optimization/37837] New: missed PRE

[rguenth at gcc dot gnu dot org]

Testcase where only one constant, not two alternative constants, are on the
entry of the threaded bb.

extern int printf (const char *, ...);

void
__attribute__((noinline))
test (double cn, int *neig)
{
  double tt, al[3];

  *neig = 3;

  if (__builtin_fabs(cn) > 1.)
    cn = -1.;

  tt = __builtin_atan2 (__builtin_sqrt (1. - __builtin_pow (cn, 2.)), cn)
       * 3.333333333333333e-1;

  al[0] = __builtin_cos (tt);
  al[1] = __builtin_cos (2.0943951023931944 + tt);
  al[2] = __builtin_cos (4.1887902047863879 + tt);

  if ((__builtin_fabs ( al[0] - al[1]) < 1.e-5)
      || (__builtin_fabs (al[0] - al[2]) < 1.e-5)
      || (__builtin_fabs (al[1] - al[2]) < 1.e-5))
    *neig = 2;
}

int
main ()
{
  int neig;

  test (-1.0, &neig);
  printf ("neig = %d\n", neig);
  if (neig != 2)
    __builtin_abort ();
  test (1.0, &neig);
  printf ("neig = %d\n", neig);
  if (neig != 2)
    __builtin_abort ();
  test (-2.0, &neig);
  printf ("neig = %d\n", neig);
  if (neig != 2)
    __builtin_abort ();
  return 0;  
}


cn == -1 is available.


-- 
           Summary: missed PRE
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rguenth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37837