tree-ssa-propagate.c (substitute_and_fold): Substitute statements in a basic-block with a backward walk.

2008-04-15  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-propagate.c (substitute_and_fold): Substitute
	statements in a basic-block with a backward walk.  Do not
	substitute into dead statements but instead remove those.

	* gcc.dg/fold-compare-2.c: Adjust testcase.
	* gcc.dg/tree-ssa/pr21086.c: Likewise.

From-SVN: r134322