2011-09-06  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/48317
	* tree-ssa-sccvn.h (struct vn_nary_op_s): Make op a true
	trailing array.
	(sizeof_vn_nary_op): New inline function.
	(vn_nary_op_lookup_pieces): Adjust.
	(vn_nary_op_insert_pieces): Likewise.
	* tree-ssa-sccvn.c (vn_nary_op_eq): Also compare the length.
	(init_vn_nary_op_from_pieces): Adjust signature.  Deal with
	any number of operands.
	(vn_nary_length_from_stmt): New function.
	(init_vn_nary_op_from_stmt): Adjust for CONSTRUCTOR handling.
	(vn_nary_op_lookup_pieces): Adjust signature and allocate properly
	sized temporary.
	(vn_nary_op_lookup): Likewise.
	(vn_nary_op_lookup_stmt): Likewise.
	(vn_nary_op_insert_into): Likewise.
	(vn_nary_op_insert_stmt): Likewise.
	(visit_use): Handle CONSTRUCTOR as nary.
	* tree-ssa-pre.c (phi_translate_1): Adjust.
	(create_expression_by_pieces): Likewise.
	(compute_avail): Likewise.

	* gcc.dg/tree-ssa/ssa-fre-31.c: New testcase.

From-SVN: r178595