re PR tree-optimization/85244 (Bad optimisation with flexible array member (may be related to -ftree-dominator-opts))

2018-04-06  Richard Biener  <rguenther@suse.de>

	PR middle-end/85244
	* tree-dfa.c (get_ref_base_and_extent): Reset seen_variable_array_ref
	after seeing a component reference with an adjacent field.  Treat
	refs to arrays at struct end of external decls similar to
	refs to unconstrained commons.

	* gcc.dg/torture/pr85244-1.c: New testcase.
	* gcc.dg/torture/pr85244-2.c: Likewise.

From-SVN: r259168