[Bug c/43798] [8/9 Regression] attribute((aligned(x))) not honored for array element types?

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43798

--- Comment #14 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Acjusted patch that uses build_aligned_type instead of doing it on its own.
--- gcc/stor-layout.c.jj        2019-01-01 12:37:17.296972670 +0100
+++ gcc/stor-layout.c   2019-03-20 11:15:12.166935041 +0100
@@ -2547,13 +2547,32 @@ layout_type (tree type)
           large as the element alignment.  */
        if (TYPE_SIZE_UNIT (element)
            && TREE_CODE (TYPE_SIZE_UNIT (element)) == INTEGER_CST
+           && !integer_zerop (TYPE_SIZE_UNIT (element)))
+         {
            /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
               TYPE_ALIGN_UNIT.  */
-           && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element))
-           && !integer_zerop (TYPE_SIZE_UNIT (element))
-           && compare_tree_int (TYPE_SIZE_UNIT (element),
-                                TYPE_ALIGN_UNIT (element)) < 0)
-         error ("alignment of array elements is greater than element size");
+           if (!TREE_OVERFLOW (TYPE_SIZE_UNIT (element))
+               && compare_tree_int (TYPE_SIZE_UNIT (element),
+                                    TYPE_ALIGN_UNIT (element)) < 0)
+             error ("alignment of array elements is greater than "
+                    "element size");
+           if (TYPE_ALIGN_UNIT (element))
+             {
+               unsigned align = (TREE_INT_CST_LOW (TYPE_SIZE_UNIT (element))
+                                 & (TYPE_ALIGN_UNIT (element) - 1));
+               align = least_bit_hwi (align);
+               if (align && align != TYPE_ALIGN_UNIT (element))
+                 {
+                   /* If the size of the element is not a multiple of
+                      alignment, lower the alignment of the elements of the
+                      array, but keep the whole array alignment.  */
+                   element
+                     = build_aligned_type (element, align * BITS_PER_UNIT);
+                   TREE_TYPE (type) = element;
+                   TYPE_USER_ALIGN (type) = 1;
+                 }
+             }
+         }
        break;
       }