* params.c (set_param_value_internal): New.
	(set_param_value): Use set_param_value_internal.
	(maybe_set_param_value, set_default_param_value): New.
	* params.h (PARAM_VALUE, PARAM_SET_P): Make into rvalues.
	(maybe_set_param_value, set_default_param_value): Declare.
	* config/arm/arm.c (arm_option_override): Use
	maybe_set_param_value.
	* config/i386/i386.c (ix86_option_override_internal): Use
	maybe_set_param_value.
	* config/ia64/ia64.c (ia64_option_default_params,
	TARGET_OPTION_DEFAULT_PARAMS): New.
	(ia64_option_optimization): Move some code to
	ia64_option_default_params.
	* config/picochip/picochip.c (picochip_option_override): Use
	maybe_set_param_value.
	* config/rs6000/rs6000.c (rs6000_option_default_params,
	TARGET_OPTION_DEFAULT_PARAMS): New.
	(rs6000_option_override_internal): Use maybe_set_param_value.
	(rs6000_option_optimization): Move some code to
	rs6000_option_default_params.
	* config/s390/s390.c (s390_option_override): Use
	maybe_set_param_value.
	* config/sh/sh.c (sh_option_default_params,
	TARGET_OPTION_DEFAULT_PARAMS): New.
	(sh_option_optimization): Move some code to
	sh_option_default_params.
	* config/sparc/sparc.c (sparc_option_override): Use
	maybe_set_param_value.
	* config/spu/spu.c (spu_option_default_params,
	TARGET_OPTION_DEFAULT_PARAMS): New.
	(spu_option_optimization): Move some code to
	spu_option_default_params.
	(spu_option_override): Use maybe_set_param_value.
	* doc/tm.texi.in (TARGET_OPTION_DEFAULT_PARAMS): New @hook.
	* doc/tm.texi: Regenerate.
	* ggc-common.c (init_ggc_heuristics): Use set_default_param_value.
	* opts.c (init_options_once): Use PARAM_VALUE not direct access to
	compiler_params.
	(default_options_optimization): Use maybe_set_param_value.
	(finish_options): Use maybe_set_param_value.
	* target.def (target_option.default_params): New hook.
	* toplev.c (general_init): Call
	targetm.target_option.default_params.

From-SVN: r165303