Avoid VMAT_ELEMENTWISE for negative stride SLP

The following makes us always use VMAT_STRIDED_SLP for negative
stride multi-element accesses.  That handles falling back to
single element accesses transparently.

	* tree-vect-stmts.cc (get_load_store_type): Use VMAT_STRIDED_SLP
	for negative stride accesses when VMAT_CONTIGUOUS_REVERSE
	isn't applicable.

diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index f78acaf0a4436ef0f885d5d9b5b3940b842a250a..852bc401035e66c86052b77ff9b19d0d074b205d 100644 (file)
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -2026,6 +2026,7 @@ get_load_store_type (vec_info  *vinfo, stmt_vec_info stmt_info,
      without permutation.  */
   if (! SLP_TREE_LOAD_PERMUTATION (slp_node).exists ())
     first_dr_info = STMT_VINFO_DR_INFO (SLP_TREE_SCALAR_STMTS (slp_node)[0]);
+
   if (STMT_VINFO_STRIDED_P (first_stmt_info))
     /* Try to use consecutive accesses of as many elements as possible,
        separated by the stride, until we have a complete vector.
@@ -2089,15 +2090,10 @@ get_load_store_type (vec_info  *vinfo, stmt_vec_info stmt_info,
                (vinfo, stmt_info, vectype, vls_type, 1,
                 &neg_ldst_offset);
          else
-           {
-             /* Try to use consecutive accesses of DR_GROUP_SIZE elements,
-                separated by the stride, until we have a complete vector.
-                Fall back to scalar accesses if that isn't possible.  */
-             if (multiple_p (nunits, group_size))
-               *memory_access_type = VMAT_STRIDED_SLP;
-             else
-               *memory_access_type = VMAT_ELEMENTWISE;
-           }
+           /* We can fall back to VMAT_STRIDED_SLP since that does
+              not care whether the stride between the group instances
+              is positive or negative.  */
+           *memory_access_type = VMAT_STRIDED_SLP;
        }
       else if (cmp == 0 && loop_vinfo)
        {