2011-09-08  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/19831
	* tree-ssa-dce.c (mark_stmt_if_obviously_necessary): Do not mark
	allocation functions as necessary.

	* gcc.dg/tree-ssa/ssa-dce-8.c: New testcase.

From-SVN: r178683