Fix ICE in get_initial_defs_for_reduction (PR 88567)

[Richard Sandiford]

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.sandif...@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);
 }