Multiple fixes: PRs 14692, 15274 and 15463

Multiple fixes: PRs 14692, 15274 and 15463

	PR c++/15463
	* loop-iv.c (iv_number_of_iterations):  Use trunc_int_for_mode on
	result of inverse.

	PR rtl-optimization/15274
	* loop-iv.c (determine_max_iter, shorten_into_mode,
	iv_number_of_iterations): Handle constants correctly.
	* rtl.h (get_mode_bounds): Declaration changed.
	* stor-layout.c (get_mode_bounds): Return a constant suitable for
	the target mode.

	PR rtl-optimization/14692
	* loop-unswitch.c (may_unswitch_on): Try folding the result.
	(unswitch_single_loop): Work correctly when may_unswitch_on
	returns a folded constant.

	* loop-iv.c (implies_p): Handle A < B ==> A + 1 <= B.
	* simplify-rtx.c (simplify_const_relational_operation): Optimize
	comparisons with mode bounds.

	* function.c (struct temp_slot): Add new field prev.
	(free_after_compilation, init_temp_slots): Free new fields.
	(cut_slot_from_list, insert_slot_to_list,
	temp_slots_at_level, max_slot_level, move_slot_to_level,
	make_slot_available): New functions.
	(assign_stack_temp_for_type, combine_temp_slots,
	find_temp_slot_from_address, preserve_temp_slots,
	preserve_rtl_expr_result, free_temp_slots,
	free_temps_for_rtl_expr, pop_temp_slots): Work with
	the new structure of lists.
	(mark_all_temps_used): Removed.
	* function.h (struct function): Field x_temp_slots
	replaced by x_used_temp_slots and x_avail_temp_slots.
	(temp_slots): Replaced by ...
	(used_temp_slots, avail_temp_slots): New.
	* tree.h (mark_all_temps_used): Declaration removed.

	* loop-iv.c (mark_single_set, get_biv_step_1, iv_analyze,
	simplify_using_assignment): Take the expression out of
	the expr_list wrapper.

	* loop-iv.c (iv_number_of_iterations): Improve clasification of
	infinite loops.

From-SVN: r82028