re PR tree-optimization/71901 (ice in find_or_generate_expression)

2016-07-19  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/71901
	* tree-ssa-sccvn.h (struct vn_reference_op_struct): Add
	align member, group stuff with the bitfield.
	(vn_ref_op_align_unit): New inline.
	* tree-ssa-sccvn.c (copy_reference_ops_from_ref): For ARRAY_REFs
	record element alignment and operand 3 unchanged.
	(ao_ref_init_from_vn_reference): Adjust.
	(valueize_refs_1): Likewise.
	* tree-ssa-pre.c (create_component_ref_by_pieces_1): Likewise.

	* gcc.dg/torture/pr71901.c: New testcase.

From-SVN: r238468