Fix ICE in get_initial_defs_for_reduction (PR 88567)

The use of "j" in:

	      init = permute_results[number_of_vectors - j - 1];

was out-of-sync with the new flat loop structure.  Now that all that
reversing is gone, we can just use the result of duplicate_and_interleave
directly.

The other cases shouldn't be affected by postponing the insertion
of ctor_seq, since gimple_build* appends to the seq without clearing
it first (unlike some of the gimplify routines).

The ICE is already covered by gcc.dg/vect/pr63379.c.

Tested on aarch64-linux-gnu (with and without SVE), aarch64_be-elf
and x86_64-linux-gnu.  OK to install?

Richard


2019-01-07  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	PR middle-end/88567
	* tree-vect-loop.c (get_initial_defs_for_reduction): Pass the
	output vector directly to duplicate_and_interleave instead of
	going through a temporary.  Postpone insertion of ctor_seq to
	the end of the loop.

On Mon, Jan 7, 2019 at 2:27 PM Richard Sandiford
<richard.sandiford@arm.com> wrote:
>
> The use of "j" in:
>
>               init = permute_results[number_of_vectors - j - 1];
>
> was out-of-sync with the new flat loop structure.  Now that all that
> reversing is gone, we can just use the result of duplicate_and_interleave
> directly.
>
> The other cases shouldn't be affected by postponing the insertion
> of ctor_seq, since gimple_build* appends to the seq without clearing
> it first (unlike some of the gimplify routines).
>
> The ICE is already covered by gcc.dg/vect/pr63379.c.
>
> Tested on aarch64-linux-gnu (with and without SVE), aarch64_be-elf
> and x86_64-linux-gnu.  OK to install?

OK.

Richard.

> Richard
>
>
> 2019-01-07  Richard Sandiford  <richard.sandiford@arm.com>
>
> gcc/
>         PR middle-end/88567
>         * tree-vect-loop.c (get_initial_defs_for_reduction): Pass the
>         output vector directly to duplicate_and_interleave instead of
>         going through a temporary.  Postpone insertion of ctor_seq to
>         the end of the loop.
>
> Index: gcc/tree-vect-loop.c
> ===================================================================
> --- gcc/tree-vect-loop.c        2019-01-04 11:39:26.674251052 +0000
> +++ gcc/tree-vect-loop.c        2019-01-07 13:23:22.924449595 +0000
> @@ -4103,7 +4103,6 @@ get_initial_defs_for_reduction (slp_tree
>    unsigned int group_size = stmts.length ();
>    unsigned int i;
>    struct loop *loop;
> -  auto_vec<tree, 16> permute_results;
>
>    vector_type = STMT_VINFO_VECTYPE (stmt_vinfo);
>
> @@ -4138,6 +4137,7 @@ get_initial_defs_for_reduction (slp_tree
>    bool constant_p = true;
>    tree_vector_builder elts (vector_type, nunits, 1);
>    elts.quick_grow (nunits);
> +  gimple_seq ctor_seq = NULL;
>    for (j = 0; j < nunits * number_of_vectors; ++j)
>      {
>        tree op;
> @@ -4163,7 +4163,6 @@ get_initial_defs_for_reduction (slp_tree
>
>        if (number_of_places_left_in_vector == 0)
>         {
> -         gimple_seq ctor_seq = NULL;
>           tree init;
>           if (constant_p && !neutral_op
>               ? multiple_p (TYPE_VECTOR_SUBPARTS (vector_type), nunits)
> @@ -4189,16 +4188,11 @@ get_initial_defs_for_reduction (slp_tree
>           else
>             {
>               /* First time round, duplicate ELTS to fill the
> -                required number of vectors, then cherry pick the
> -                appropriate result for each iteration.  */
> -             if (vec_oprnds->is_empty ())
> -               duplicate_and_interleave (&ctor_seq, vector_type, elts,
> -                                         number_of_vectors,
> -                                         permute_results);
> -             init = permute_results[number_of_vectors - j - 1];
> +                required number of vectors.  */
> +             duplicate_and_interleave (&ctor_seq, vector_type, elts,
> +                                       number_of_vectors, *vec_oprnds);
> +             break;
>             }
> -         if (ctor_seq != NULL)
> -           gsi_insert_seq_on_edge_immediate (pe, ctor_seq);
>           vec_oprnds->quick_push (init);
>
>           number_of_places_left_in_vector = nunits;
> @@ -4207,6 +4201,8 @@ get_initial_defs_for_reduction (slp_tree
>           constant_p = true;
>         }
>      }
> +  if (ctor_seq != NULL)
> +    gsi_insert_seq_on_edge_immediate (pe, ctor_seq);
>  }
>
>