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.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@111300 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 18 insertions, 3 deletions

diff --git a/gcc/tree-ssa-operands.c b/gcc/tree-ssa-operands.c
index 748ff5d62f6..de578a74df1 100644
--- a/gcc/tree-ssa-operands.c
+++ b/gcc/tree-ssa-operands.c
@@ -1844,11 +1844,26 @@ add_virtual_operand (tree var, stmt_ann_t s_ann, int flags,
 	     
 	     It is also necessary to add bare defs on clobbers for
 	     TMT's, so that bare TMT uses caused by pruning all the
-	     aliases will link up properly with calls.   */
+	     aliases will link up properly with calls.   In order to
+	     keep the number of these bare defs we add down to the
+	     minimum necessary, we keep track of which TMT's were used
+	     alone in statement defs or vuses.  */
+
 	  if (v_ann->is_aliased
 	      || none_added
-	      || (TREE_CODE (var) == TYPE_MEMORY_TAG && for_clobber))
-	    append_v_may_def (var);
+	      || (TREE_CODE (var) == TYPE_MEMORY_TAG && for_clobber
+		  && TMT_USED_ALONE (var)))
+	    {
+	      /* Every bare tmt def we add should have TMT_USED_ALONE
+		 set on it, or else we will get the wrong answer on
+		 clobbers.  */
+
+	      if (none_added && !updating_used_alone && aliases_computed_p
+		  && TREE_CODE (var) == TYPE_MEMORY_TAG)
+		gcc_assert (TMT_USED_ALONE (var));
+
+	      append_v_may_def (var);
+	    }
 	}
       else
 	{