* config.gcc: Add support for --enable-e500_double.

	* config/rs6000/e500-double.h: New file.

	* config/rs6000/rs6000.h: Define TARGET_E500_SINGLE and
	TARGET_E500_DOUBLE.

	* config/rs6000/eabi.h: Define TARGET_E500_SINGLE and
	TARGET_E500_DOUBLE.

	* config/rs6000/linuxspe.h: Same.

	* doc/invoke.texi (Option Summary): Document new options for
	mfloat-gprs.
	(RS/6000 and PowerPC Options): Same.

	* config/rs6000/rs6000.c (rs6000_parse_float_gprs_option): New
	function.
	(rs6000_override_options): Use it.  Use
	SUB3TARGET_OVERRIDE_OPTIONS.
	Add 8548 to processor_target_table.
	(rs6000_legitimate_address): Handle e500 doubles.
	(rs6000_legitimize_address): Same.
	(rs6000_legitimize_reload_address): Same.
	(rs6000_hard_regno_nregs): Same.
	(spe_func_has_64bit_regs_p): Same.
	(emit_frame_save): Same.
	(gen_frame_mem_offset): Same.
	(rs6000_dwarf_register_span): Same.
	(rs6000_generate_compare): Same.
	(easy_fp_constant): Same.
	(legitimate_offset_address_p): Same.

	* config/rs6000/spe.md: (cmdfeq_gpr): New.
	(tstdfeq_gpr): New.
	(cmpdfgt_gpr): New.
	(tstdfgt_gpr): New.
	(tstdfgt_gpr): New.
	(cmpdflt_gpr): New.
	(tstdflt_gpr): New.
	Add new constants.

From-SVN: r89416