First, the example you gave is poor programming practice.  It has
been common practice to place the largest objects first in structures, if
for no other reason than to prevent the compiler from wasting space with
alignment padding.

	What I suspect is that you want to change
rs6000.c:expand_block_move() so that it does not use DImode (floating
point on 32-bit architecture) moves for objects that are not at least word
aligned.

David