2006-02-20  Daniel Berlin  <dberlin@dberlin.org>

	* tree.h (struct tree_memory_tag): Add is_used_alone member.
	(TMT_USED_ALONE): New macro.
	* tree-pass.h (PROP_tmt_usage): New property.
	(TODO_update_tmt_usage): New todo.
	* tree-ssa-alias.c (updating_used_alone): New variable.
	(recalculate_used_alone): New function.	  
	(compute_may_aliases): Set updating_used_alone, call
	recalculate_used_alone. 
	* tree-sra.c (pass_sra): Note that this pass destroys
	PROP_tmt_usage, and add TODO_update_tmt_usage.
	* tree-ssa-forwprop.c (pass_forwprop): Ditto.
	* tree-flow.h (updating_used_alone): Prototype.
	(recalculate_used_alone): Ditto.
	* passes.c (execute_todo): Add code to set updating_used_alone,
	and call recalculate.
	* tree-ssa-operands.c (add_virtual_operand): Only append bare def
	for clobber if used alone, and add assert to verify used_alone
	status.

From-SVN: r111300