[Bug tree-optimization/61034] Optimizing takes too many passes

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61034

--- Comment #7 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to rguenther@suse.de from comment #6)
> that's a conditional assignment AFAICS

Ah, you are right of course. It shouldn't be conditional, but it will take a
VRP pass to notice that. If I schedule another FRE right after VRP1, things
optimize nicely, and after some cleanup by DOM+DSE, DCE2 can remove all
malloc+free. However, if I don't add this extra FRE pass, we somehow don't
manage. Note that in the PRE dump, with just your patch (no extra pass), I see:

  pretmp_92 = 1;
  _235 = pretmp_92;
  if (_235 == 0)

and these conditions seem to be what prevents us from finishing the job.