re PR tree-optimization/39207 (Strict aliasing warnings in libstdc++ headers)

2009-02-17  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/39207
	* tree-ssa-structalias.c (find_what_p_points_to): Do not emit
	strict-aliasing warnings for pointers pointing to NULL.

From-SVN: r144228

gcc/ChangeLog

+2009-02-17  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/39207
+	* tree-ssa-structalias.c (find_what_p_points_to): Do not emit
+	strict-aliasing warnings for pointers pointing to NULL.
+
 2009-02-16  Joseph Myers  <joseph@codesourcery.com>
 
 	PR c/35446

gcc/tree-ssa-structalias.c

@@ -4935,6 +4935,7 @@ find_what_p_points_to (tree p)
 	    {
 	      pi->pt_vars = NULL;
 	      if (pruned > 0
+		  && !pi->pt_null
 		  && pi->is_dereferenced
 		  && warn_strict_aliasing > 0
 		  && !SSA_NAME_IS_DEFAULT_DEF (p))