PR tree-optimization/79472

	PR tree-optimization/79472
	* tree-switch-conversion.c (struct switch_conv_info): Add
	contiguous_range and default_case_nonstandard fields.
	(collect_switch_conv_info): Compute contiguous_range and
	default_case_nonstandard fields, don't clear final_bb if
	contiguous_range and only the default case doesn't have the required
	structure.
	(check_all_empty_except_final): Set default_case_nonstandard instead
	of failing if contiguous_range and the default case doesn't have empty
	block.
	(check_final_bb): Add SWTCH argument, don't fail if contiguous_range
	and only the default case doesn't have the required constants.  Skip
	virtual phis.
	(gather_default_values): Skip virtual phis.  Allow non-NULL CASE_LOW
	if default_case_nonstandard.
	(build_constructors): Build constant 1 just once.  Assert that default
	values aren't inserted in between cases if contiguous_range.  Skip
	virtual phis.
	(build_arrays): Skip virtual phis.
	(prune_bbs): Add DEFAULT_BB argument, don't remove that bb.
	(fix_phi_nodes): Don't add e2f phi arg if default_case_nonstandard.
	Handle virtual phis.
	(gen_inbound_check): Handle default_case_nonstandard case.
	(process_switch): Adjust check_final_bb caller.  Call
	gather_default_values with the first non-default case instead of
	default case if default_case_nonstandard.

	* gcc.dg/tree-ssa/vrp40.c: Add -fno-tree-switch-conversion to dg-options.
	* gcc.dg/tree-ssa/vrp113.c: New test.
	* gcc.dg/tree-ssa/cswtch-3.c: New test.
	* gcc.dg/tree-ssa/cswtch-4.c: New test.
	* gcc.dg/tree-ssa/cswtch-5.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@247538 138bc75d-0d04-0410-961f-82ee72b054a4