[Bug c++/8781] Pessimization of C++ (functional) code

[rguenth at gcc dot gnu dot org]

------- Comment #23 from rguenth at gcc dot gnu dot org  2009-04-03 11:37 
-------
On trunk we get the following after early optimizations:

<bb 2>:
  predD.2646 = fD.2070;
  predD.2653.predD.2098 = &predD.2646;
  predD.2660.predD.2116 = &predD.2653;
  predD.2667.predD.2134 = &predD.2660;
  predD.2674.predD.2152 = &predD.2667;
  predD.2681.predD.2170 = &predD.2674;
  predD.2688.predD.2188 = &predD.2681;
  predD.2695.predD.2206 = &predD.2688;
  predD.2702.predD.2224 = &predD.2695;
  D.2720_24 = predD.2702.predD.2224;
  D.2728_25 = D.2720_24->predD.2206;
  D.2721_26 = D.2728_25->predD.2188;
  D.2727_27 = D.2721_26->predD.2170;
  D.2722_28 = D.2727_27->predD.2152;
  D.2726_29 = D.2722_28->predD.2134;
  D.2723_30 = D.2726_29->predD.2116;
  D.2725_31 = D.2723_30->predD.2098;
  D.2724_32 = *D.2725_31;
  D.2719_33 = D.2724_32 ();
  return D.2719_33;

now, while SCCVN figures out that predD.2702.predD.2224 loads &predD.2695 it
is not able to cascade here, which is because we do not "simplify" the
vn references after substituting the value-numbers (PR37892).


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |37892
   Last reconfirmed|2006-04-05 16:11:16         |2009-04-03 11:37:53
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8781