* rtl.h (validate_subreg): Declare.
        * emit-rtl.c (validate_subreg): New.
        (gen_rtx_SUBREG): Use it.
        * simplify-rtx.c (simplify_subreg): Likewise.
        (simplify_gen_subreg): Likewise.  Remove duplicate asserts.
        * expr.c (emit_move_insn_1): Tidy complex move code.  Use memory
        fallback whenever gen_realpart/gen_imagpart would not be able to
        create SUBREGs.

From-SVN: r91126