* explow.c (trunc_int_for_mode): New function.
        (plus_constant_wide): Use it.
        * combine.c (simplify_and_const_int): Likewise.
        (merge_outer_ops): Likewise.
        (simplify_shift_const): Likewise.
        * cse.c (simplify_unary_operation): Likewise.
        (simplify_binary_operation): Likewise.
        * emit-rtl.c (operand_subword): Likewise.
        * rtl.h: Declare it.

From-SVN: r28222