[Bug middle-end/89544] Argument marshalling incorrectly assumes stack slots are naturally aligned.

[rearnsha at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89544

--- Comment #1 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
I think things start to go wrong in assign_parm_find_data_types.  That calls
promote_function_mode, but that then has no target-specific action when the
type is a RECORD_TYPE, and it never calls the back-end in this case.

If it did, then the backend could change the promoted mode to BLKmode to
represent the fact that the object was not correctly aligned on the stack, and
presumably the code would then be forced into a more sensible action.