Comment 20 for bug 604874

Looks like the culprit may be this patch, which also went upstream. I checked upstream GCC, and it seems broken on the test case (on all platforms) as well ...

2009-06-11 Nathan Froyd <email address hidden>

       Backport from upstream:

       2009-06-10 Nathan Froyd <email address hidden>
       gcc/
       * tree.h (tree_base): Add packed_flag and user_align fields.
       Decrease size of spare field.
       (TYPE_USER_ALIGN): Use user_align from tree_base.
       (DECL_USER_ALIGN): Likewise.
       (TYPE_PACKED): Use packed_flag from tree_base.
       (DECL_PACKED): Likewise.
       (tree_type): Delete packed_flag and user_align fields. Widen
       precision field. Widen mode field and shuffle fields to align
       mode on an 8-bit boundary.
       (tree_decl_common): Delete decl_flag_1 and user_align fields.
       Renumber decl_flag_* fields. Fix comments. Widen
       decl_common_unused field.
       (DECL_HAS_VALUE_EXPR_P): Adjust for renumbering of decl_flag_*
       fields.
       (DECL_EXTERNAL): Likewise.
       (DECL_BIT_FIELD): Likewise.
       (DECL_NONADDRESSABLE_P): Likewise.
       (TYPE_DECL_SUPRESS_DEBUG): Likewise.
       * config/arm/arm-modes.def (XImode): Make it an INT_MODE.

http://gcc.gnu.org/ml/gcc-patches/2009-06/msg00763.html