2008-02-20  Richard Guenther  <rguenther@suse.de>

	* tree.h (fold_real_zero_addition_p): Declare.
	* fold-const.c (fold_real_zero_addition_p): Export.
	* tree-ssa-reassoc.c (eliminate_using_constants): Also handle
	floating-point operations with zero and one.

	* gcc.dg/tree-ssa/reassoc-13.c: New testcase.

From-SVN: r132480