(convert_move, convert_to_mode): Strip off a SUBREG made for variables with
promoted modes.
(store_expr): Store into variables with promoted modes by doing the
appropriate extension operation.
(expand_expr, case VAR_DECL): Generate SUBREGs for promoted objects.
(expand_expr, case SAVE_EXPR): Likewise for SAVE_EXPRs.
(expand_increment): Handle increment of promoted objects.

From-SVN: r2174