2009-03-31  Richard Guenther  <rguenther@suse.de>

	PR middle-end/31029
	* fold-const.c (fold_binary): Fold X +- Y CMP X to Y CMP 0 for
	equality comparisons.  Fold C - X CMP X if C % 2 == 1.

	* gcc.dg/fold-compare-4.c: New testcase.
	* gcc.dg/fold-compare-5.c: Likewise.

From-SVN: r145345