tree-optimization/118405 - ICE with vector(1) T vs T load

When vectorizing a load we are now checking alignment before emitting
a vector(1) T load instead of blindly assuming it's OK when we had
a scalar T load.  For reasons we're not handling alignment computation
optimally here but we shouldn't ICE when we fall back to loads of T.

The following ensures the IL remains correct by emitting VIEW_CONVERT
from T to vector(1) T when needed.  It also removes an earlier fix
done in r9-382-gbb4e47476537f6 for the same issue with VMAT_ELEMENTWISE.

	PR tree-optimization/118405
	* tree-vect-stmts.cc (vectorizable_load): When we fall back
	to scalar loads make sure we properly convert to vector(1) T
	when there was only a single vector element.

diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index f5b3608f6b13f1951703f6015b8b01ef966e6693..0c0f999d3e3c2f73b14a33055d34cc1043b3704c 100644 (file)
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -10731,9 +10731,6 @@ vectorizable_load (vec_info *vinfo,
          /* Else fall back to the default element-wise access.  */
          ltype = build_aligned_type (ltype, TYPE_ALIGN (TREE_TYPE (vectype)));
        }
-      /* Load vector(1) scalar_type if it's 1 element-wise vectype.  */
-      else if (nloads == 1)
-       ltype = vectype;
 
       if (slp)
        {
@@ -10782,11 +10779,11 @@ vectorizable_load (vec_info *vinfo,
                                             group_el * elsz + cst_offset);
              tree data_ref = build2 (MEM_REF, ltype, running_off, this_off);
              vect_copy_ref_info (data_ref, DR_REF (first_dr_info->dr));
-             new_stmt = gimple_build_assign (make_ssa_name (ltype), data_ref);
+             new_temp = make_ssa_name (ltype);
+             new_stmt = gimple_build_assign (new_temp, data_ref);
              vect_finish_stmt_generation (vinfo, stmt_info, new_stmt, gsi);
              if (nloads > 1)
-               CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
-                                       gimple_assign_lhs (new_stmt));
+               CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, new_temp);
 
              group_el += lnel;
              if (! slp
@@ -10833,6 +10830,15 @@ vectorizable_load (vec_info *vinfo,
                    }
                }
            }
+         else if (!costing_p && ltype != vectype)
+           {
+             new_stmt = gimple_build_assign (make_ssa_name (vectype),
+                                             VIEW_CONVERT_EXPR,
+                                             build1 (VIEW_CONVERT_EXPR,
+                                                     vectype, new_temp));
+             vect_finish_stmt_generation (vinfo, stmt_info, new_stmt,
+                                          gsi);
+           }
 
          if (!costing_p)
            {