genattrtab.c (attr_rtx_cost): Move earlier, start with cost being 1.

genattrtab.c (attr_rtx_cost): Move earlier, start with cost being 1.

	* genattrtab.c (attr_rtx_cost): Move earlier, start with cost being 1.
	(simplify_test_exp): Handle one more case of distributive law,
	decrease cost threshold.
	(tests_attr_p, get_attr_order): New functions.
	(optimize_attrs): Use topological order, inline only cheap values.
	(write_attr_set): Reset our_known_true after some time.

From-SVN: r187714