[Bug tree-optimization/25290] PHI-OPT could be rewritten so that is uses fold

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25290

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 40185
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40185&action=edit
The start of the patch

Note this is just a start of the rewrite.  It needs improvement as it started
out really part of another patch which added a generic (non-loop based) ifcvt
to the tree level.  But I wanted to get it recorded somewhere so I don't lose
it again.  Note the problem I mentioned in comment #8 I don't hit any more.