2005-01-29  Richard Guenther <richard.guenther@uni-tuebingen.de>

	PR tree-optimization/15791
	* fold-const.c (extract_array_ref): New function.
	(fold): Fold comparisons between &a[i] and &a[j] or
	semantically equivalent trees.

	* gcc.dg/tree-ssa/pr15791-1.c: New testcase.
	* gcc.dg/tree-ssa/pr15791-2.c: Likewise.
	* gcc.dg/tree-ssa/pr15791-3.c: Likewise.
	* gcc.dg/tree-ssa/pr15791-4.c: Likewise.
	* gcc.dg/tree-ssa/pr15791-5.c: Likewise.
	* g++.dg/tree-ssa/pr15791-1.C: Likewise.
	* g++.dg/tree-ssa/pr15791-2.C: Likewise.
	* g++.dg/tree-ssa/pr15791-3.C: Likewise.
	* g++.dg/tree-ssa/pr15791-4.C: Likewise.
	* g++.dg/tree-ssa/pr15791-5.C: Likewise.

From-SVN: r94414