re PR tree-optimization/42142 (DCE miscompiles a certain quicksort implementation when optimizing with -O1 or higher)

2009-11-24  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/42142
	* tree-ssa-dce.c (mark_aliased_reaching_defs_necessary_1):
	Handle iv-dependent (non-)kills properly.
	(mark_aliased_reaching_defs_necessary): Pass the basic-block
	of the reference statement to mark_aliased_reaching_defs_necessary_1.

	* gcc.c-torture/execute/pr42142.c: New testcase.

From-SVN: r154494