[Bug tree-optimization/52091] [4.7 Regression] ICE: verify_gimple failed

["irar at il dot ibm.com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52091

--- Comment #7 from Ira Rosen <irar at il dot ibm.com> 2012-02-02 15:16:18 UTC ---
(In reply to comment #6)
> (In reply to comment #5)
> > I think we should fail to vectorize D.2030_19 = prephitmp.17_21 & 65535, or any
> > other non-phi/not vect_double_reduction_def stmt with a double reduction phi as
> > a def_stmt.
> > 
> > We can either check this in every vectorizable_* for every operand, like this:
> > Index: tree-vect-stmts.c
> > ===================================================================
> > --- tree-vect-stmts.c   (revision 183125)
> > +++ tree-vect-stmts.c   (working copy)
> > @@ -3326,7 +3326,8 @@ vectorizable_operation (gimple stmt, gimple_stmt_i
> > 
> >    op0 = gimple_assign_rhs1 (stmt);
> >    if (!vect_is_simple_use_1 (op0, loop_vinfo, bb_vinfo,
> > -                            &def_stmt, &def, &dt[0], &vectype))
> > +                            &def_stmt, &def, &dt[0], &vectype)
> > +      || dt[0] == vect_double_reduction_def)
> >      {
> >        if (vect_print_dump_info (REPORT_DETAILS))
> >          fprintf (vect_dump, "use not simple.");
> > 
> > 
> > or pass stmt or stmt_info to vect_is_simple_use and check it there.
> 
> Are you going to write a patch for this?  Not sure how exactly would you like
> it to look up.
> 

We need to check that if def_stmt is vect_double_reduction_def, the stmt itself
needs to be vect_double_reduction_def. We know def_type (dt in the above patch)
of def_stmt from vect_is_simple_use. We call it from all the vectorizable_*
functions. We don't pass the stmt itself to vect_is_simple_use, therefore, we
should either do that and perform the check in vect_is_simple_use, or check
this in all the vectorizable_* (except perhaps vectorizable_reduction). I
prefer to pass stmt or stmt_info to vect_is_simple_use.

I can do this on Sunday. You are welcome to do this yourself. Whatever you
prefer.