2011-10-18  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/50672
	* tree-ssa-dce.c (mark_virtual_operand_for_renaming): New function,
	factored out of ...
	(mark_virtual_phi_result_for_renaming): Use
	mark_virtual_operand_for_renaming.
	* tree-flow.h (mark_virtual_operand_for_renaming): Declare.
	* tree-ssa-tail-merge.c (release_last_vdef): New function.
	(purge_bbs): Add update_vops parameter.  Call release_last_vdef for each
	deleted basic block.
	(tail_merge_optimize): Add argument to call to purge_bbs.

From-SVN: r180126