2007-11-23  Richard Guenther  <rguenther@suse.de>
	Michael Matz  <matz@suse.de>

	PR tree-optimization/34176
	* alloc-pool.h (empty_alloc_pool): Declare.
	* alloc-pool.c (empty_alloc_pool): New function.
	* tree-ssa-sccvn.c (vn_reference_lookup): Also lookup from the
	valid table if a lookup from the optimistic table failed.
	(vn_unary_op_lookup): Likewise.
	(vn_binary_op_lookup): Likewise.
	(vn_phi_lookup): Likewise.
	(process_scc): Clear optimistic tables before every iteration.

	* gcc.c-torture/execute/pr34176.c: New testcase.

Co-Authored-By: Michael Matz <matz@suse.de>

From-SVN: r130379