re PR tree-optimization/51879 (Missed tail merging with non-const/pure calls)

re PR tree-optimization/51879 (Missed tail merging with non-const/pure calls)

2012-04-27  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/51879
	* tree-ssa-sccvn.h (struct vn_reference_s): Add result_vdef field.
	* tree-ssa-sccvn.c (mark_use_processed): New function, factored out
	of ...
	(defs_to_varying): ... here.  Don't set use_processed.
	(visit_reference_op_call): Handle gimple_vdef.
	Handle case that lhs is NULL_TREE.
	(visit_use): Use mark_use_processed.  Handle calls with side-effect
	using visit_reference_op_call.

From-SVN: r186894