Improve switch code emission for a balanced tree (PR tree-optimization/86847).

Improve switch code emission for a balanced tree (PR tree-optimization/86847).

2018-08-27  Martin Liska  <mliska@suse.cz>

        PR tree-optimization/86847
	* tree-switch-conversion.c (switch_decision_tree::dump_case_nodes):
        Dump also subtree probability.
	(switch_decision_tree::do_jump_if_equal): New function.
	(switch_decision_tree::emit_case_nodes): Handle special
        situations in balanced tree that can be emitted much simpler.
        Fix calculation of probabilities that happen in tree expansion.
	* tree-switch-conversion.h (struct cluster): Add
        is_single_value_p.
	(struct simple_cluster): Likewise.
	(struct case_tree_node): Add new function has_child.
	(do_jump_if_equal): New.
2018-08-27  Martin Liska  <mliska@suse.cz>

        PR tree-optimization/86847
	* gcc.dg/tree-ssa/switch-3.c: New test.
	* gcc.dg/tree-ssa/vrp105.c: Remove.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@263879 138bc75d-0d04-0410-961f-82ee72b054a4