* gimple-ssa-isolate-paths.c (is_divmod_with_given_divisor): New
	function.
	(stmt_uses_name_in_undefined_way): New function, extracted from
	find_implicit_erroneous_behavior and extended for div/mod case.
	(stmt_uses_0_or_null_in_undefined_way): New function, extracted from
	find_explicit_erroneous_behavior and extended for div/mod case.
	(find_implicit_erroneous_behavior): Use new helper function.
	(find_explicit_erroneous_behavior): Use new helper function.

	* gcc.dg/tree-ssa/isolate-6.c: New test.
	* gcc.dg/tree-ssa/isolate-7.c: New test.

From-SVN: r242075