alpha.c (xfloating_ops, [...]): New.

        * config/alpha/alpha.c (xfloating_ops, vax_cvt_ops): New.
        (alpha_lookup_xfloating_lib_func): Use them, return rtx.
        (alpha_emit_xfloating_arith): Update to match.
        (alpha_emit_xfloating_compare): Likewise.
        (alpha_emit_xfloating_cvt): Likewise.
        (alpha_emit_xfloating_libcall): Take already built symbol,
        mark call const.
        * config/alpha/alpha.md (extendsftf2, extenddftf2): Take
        op1 in a register.

From-SVN: r79371