[Patch 6/17] Migrate excess precision logic to use TARGET_EXCESS_PRECISION

[Patch 6/17] Migrate excess precision logic to use TARGET_EXCESS_PRECISION

gcc/

	* toplev.c (init_excess_precision): Delete most logic.
	* tree.c (excess_precision_type): Rewrite to use
	TARGET_EXCESS_PRECISION.
	* doc/invoke.texi (-fexcess-precision): Document behaviour in a
	more generic fashion.
	* ginclude/float.h: Wrap definition of FLT_EVAL_METHOD in
	__STDC_WANT_IEC_60559_TYPES_EXT__.

gcc/c-family/

	* c-common.c (excess_precision_mode_join): New.
	(c_ts18661_flt_eval_method): New.
	(c_c11_flt_eval_method): Likewise.
	(c_flt_eval_method): Likewise.
	* c-common.h (excess_precision_mode_join): New.
	(c_flt_eval_method): Likewise.
	* c-cppbuiltin.c (c_cpp_flt_eval_method_iec_559): New.
	(cpp_iec_559_value): Call it.
	(c_cpp_builtins): Modify logic for __LIBGCC_*_EXCESS_PRECISION__,
	call c_flt_eval_method to set __FLT_EVAL_METHOD__ and
	__FLT_EVAL_METHOD_TS_18661_3__.

gcc/testsuite/

	* gcc.dg/fpermitted-flt-eval-methods_3.c: New.
	* gcc.dg/fpermitted-flt-eval-methods_4.c: Likewise.

From-SVN: r242776