[Bug target/52238] -mms-bitfields: __attribute__ ((aligned (n))) ignored for struct members

["ktietz at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52238

Kai Tietz <ktietz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ktietz at gcc dot gnu.org

--- Comment #2 from Kai Tietz <ktietz at gcc dot gnu.org> 2012-02-15 18:34:40 UTC ---
in stor-layout.c function place_field() it is said "We already align ms_struct
fields, so don't re-align them".  This isn't completely true, as desired_align
isn't handled in ms_struct case.

Following patch seems to solve this issue:

Index: stor-layout.c
===================================================================
--- stor-layout.c       (revision 184262)
+++ stor-layout.c       (working copy)
@@ -1141,15 +1141,14 @@
     }

   /* Does this field automatically have alignment it needs by virtue
-     of the fields that precede it and the record's own alignment?
-     We already align ms_struct fields, so don't re-align them.  */
-  if (known_align < desired_align
-      && !targetm.ms_bitfield_layout_p (rli->t))
+     of the fields that precede it and the record's own alignment?  */
+  if (known_align < desired_align)
     {
       /* No, we need to skip space before this field.
         Bump the cumulative size to multiple of field alignment.  */

-      if (DECL_SOURCE_LOCATION (field) != BUILTINS_LOCATION)
+      if (!targetm.ms_bitfield_layout_p (rli->t)
+          && DECL_SOURCE_LOCATION (field) != BUILTINS_LOCATION)
        warning (OPT_Wpadded, "padding struct to align %q+D", field);

       /* If the alignment is still within offset_align, just align
@@ -1302,7 +1301,7 @@
                 type size!) */
              HOST_WIDE_INT bitsize = tree_low_cst (DECL_SIZE (field), 1);

-             if (rli->remaining_in_alignment < bitsize)
+             if (rli->remaining_in_alignment < bitsize) /* $$$$ */
                {
                  HOST_WIDE_INT typesize = tree_low_cst (TYPE_SIZE (type), 1);