extend jump thread for finite state automata

	PR tree-optimization/54742
	* params.def (max-fsm-thread-path-insns, max-fsm-thread-length,
	max-fsm-thread-paths): New.

	* doc/invoke.texi (max-fsm-thread-path-insns, max-fsm-thread-length,
	max-fsm-thread-paths): Documented.

	* tree-cfg.c (split_edge_bb_loc): Export.
	* tree-cfg.h (split_edge_bb_loc): Declared extern.

	* tree-ssa-threadedge.c (simplify_control_stmt_condition): Restore the
	original value of cond when simplification fails.
	(fsm_find_thread_path): New.
	(fsm_find_control_statement_thread_paths): New.
	(thread_through_normal_block): Call find_control_statement_thread_paths.

	* tree-ssa-threadupdate.c (dump_jump_thread_path): Pretty print
	EDGE_FSM_THREAD.
	(verify_seme): New.
	(duplicate_seme_region): New.
	(thread_through_all_blocks): Generate code for EDGE_FSM_THREAD edges
	calling duplicate_seme_region.

	* tree-ssa-threadupdate.h (jump_thread_edge_type): Add EDGE_FSM_THREAD.

	* testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c: New test.
	* testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@218451 138bc75d-0d04-0410-961f-82ee72b054a4