Re: [05/46] Fix make_ssa_name call in vectorizable_reduction

[Richard Biener <richard.guenther@gmail.com>]

On Tue, Jul 24, 2018 at 11:54 AM Richard Sandiford
<richard.sandiford@arm.com> wrote:
>
> The usual vectoriser dance to create new assignments is:
>
>     new_stmt = gimple_build_assign (vec_dest, ...);
>     new_temp = make_ssa_name (vec_dest, new_stmt);
>     gimple_assign_set_lhs (new_stmt, new_temp);
>
> but one site in vectorizable_reduction used:
>
>     new_temp = make_ssa_name (vec_dest, new_stmt);
>
> before creating new_stmt.
>
> This method of creating statements probably needs cleaning up, but
> that's for another day...

Yeah, one can elide the set_lhs by first allocating the SSA name
without defining stmt and then building the stmt with the SSA def
directly...

OK

>
> 2018-07-24  Richard Sandiford  <richard.sandiford@arm.com>
>
> gcc/
>         * tree-vect-loop.c (vectorizable_reduction): Fix an instance in
>         which make_ssa_name was called with new_stmt before new_stmt
>         had been created.
>
> Index: gcc/tree-vect-loop.c
> ===================================================================
> --- gcc/tree-vect-loop.c        2018-07-24 10:22:12.737465897 +0100
> +++ gcc/tree-vect-loop.c        2018-07-24 10:22:16.421433184 +0100
> @@ -7210,9 +7210,10 @@ vectorizable_reduction (gimple *stmt, gi
>               if (op_type == ternary_op)
>                 vop[2] = vec_oprnds2[i];
>
> -             new_temp = make_ssa_name (vec_dest, new_stmt);
> -             new_stmt = gimple_build_assign (new_temp, code,
> +             new_stmt = gimple_build_assign (vec_dest, code,
>                                               vop[0], vop[1], vop[2]);
> +             new_temp = make_ssa_name (vec_dest, new_stmt);
> +             gimple_assign_set_lhs (new_stmt, new_temp);
>             }
>           vect_finish_stmt_generation (stmt, new_stmt, gsi);
>