[Bug tree-optimization/30738] suboptimal code for min, max, et al

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2007-02-09 10:54 -------
Confirmed.  This is because we don't optimize

int test_min_ref(int, int) (x, y)
{
  int D.2516;
  int D.2517;
  const int & x;
  int D.2458;

<bb 2>:
  # VUSE <x_10(D)>
  D.2516_6 = x;
  # VUSE <y_11(D)>
  D.2517_7 = y;
  if (D.2516_6 < D.2517_7) goto <L1>; else goto <L2>;

<L1>:;

  # x_8 = PHI <&y(2), &x(3)>
<L2>:;
  # VUSE <x_10(D), y_11(D)>
  D.2458_2 = *x_8;
  return D.2458_2;

}

We could "backward propagate" *a_8 into the PHI node.  This missing
optimization
also keeps x and y addressable, which is bad.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
          Component|c++                         |tree-optimization
     Ever Confirmed|0                           |1
  GCC build triplet|sparc-sun-solaris           |
   GCC host triplet|sparc-sun-solaris           |
 GCC target triplet|sparc-sun-solaris           |
           Keywords|                            |missed-optimization
      Known to fail|                            |4.3.0
   Last reconfirmed|0000-00-00 00:00:00         |2007-02-09 10:54:11
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30738