re PR libstdc++/29286 (placement new does not change the dynamic type as it should)

./:	PR libstdc++/29286
	* tree.def: Add CHANGE_DYNAMIC_TYPE_EXPR.
	* tree.h (CHANGE_DYNAMIC_TYPE_NEW_TYPE): Define.
	(CHANGE_DYNAMIC_TYPE_LOCATION): Define.
	(DECL_NO_TBAA_P): Define.
	(struct tree_decl_common): Add no_tbaa_flag field.
	* tree-ssa-structalias.c (struct variable_info): Add
	no_tbaa_pruning field.
	(new_var_info): Initialize no_tbaa_pruning field.
	(unify_nodes): Copy no_tbaa_pruning field.
	(find_func_aliases): Handle CHANGE_DYNAMIC_TYPE_EXPR.
	(dump_solution_for_var): Print no_tbaa_pruning flag.
	(set_uids_in_ptset): Add no_tbaa_pruning parameter.  Change all
	callers.
	(compute_tbaa_pruning): New static function.
	(compute_points_to_sets): Remove CHANGE_DYNAMIC_TYPE_EXPR nodes.
	Call compute_tbaa_pruning.
	* tree-ssa-alias.c (may_alias_p): Test no_tbaa_flag for pointers.
	* gimplify.c (gimplify_expr): Handle CHANGE_DYNAMIC_TYPE_EXPR.
	* gimple-low.c (lower_stmt): Likewise.
	* tree-gimple.c (is_gimple_stmt): Likewise.
	* tree-ssa-operands.c (get_expr_operands): Likewise.
	* tree-ssa-dce.c (mark_stmt_if_obviously_necessary): Likewise.
	* tree-inline.c (estimate_num_insns_1): Likewise.
	(copy_result_decl_to_var): Likewise.
	* expr.c (expand_expr_real_1): Likewise.
	* tree-pretty-print.c (dump_generic_node): Likewise.
	* tree-inline.c (copy_decl_to_var): Copy DECL_NO_TBAA_P flag.
	* omp-low.c (omp_copy_decl_2): Likewise.
	* print-tree.c (print_node): Print DECL_NO_TBAA_P flag.
	* doc/c-tree.texi (Expression trees): Document
	CHANGE_DYNAMIC_TYPE_EXPR.
cp/:
	PR libstdc++/29286
	* init.c (avoid_placement_new_aliasing): New static function.
	(build_new_1): Call it.
testsuite/:
	PR libstdc++/29286
	* g++.dg/init/new16.C: New test.
	* g++.dg/init/new17.C: New test.
	* g++.dg/init/new18.C: New test.
	* g++.dg/init/new19.C: New test.

Co-Authored-By: Daniel Berlin <dberlin@dberlin.org>

From-SVN: r125653

1 files changed, 56 insertions, 53 deletions

diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 9fa3129..cf5dc2b 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -1,5 +1,5 @@
 /* Alias analysis for trees.
-   Copyright (C) 2004, 2005 Free Software Foundation, Inc.
+   Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
    Contributed by Diego Novillo <dnovillo@redhat.com>
 
 This file is part of GCC.
@@ -2720,69 +2720,72 @@ may_alias_p (tree ptr, HOST_WIDE_INT mem_alias_set,
 
   gcc_assert (TREE_CODE (mem) == SYMBOL_MEMORY_TAG);
 
-  alias_stats.tbaa_queries++;
-
-  /* If the alias sets don't conflict then MEM cannot alias VAR.  */
-  if (!alias_sets_conflict_p (mem_alias_set, var_alias_set))
+  if (!DECL_NO_TBAA_P (ptr))
     {
-      alias_stats.alias_noalias++;
-      alias_stats.tbaa_resolved++;
-      return false;
-    }
+      alias_stats.tbaa_queries++;
 
-  /* If VAR is a record or union type, PTR cannot point into VAR
-     unless there is some explicit address operation in the
-     program that can reference a field of the type pointed-to by PTR.
-     This also assumes that the types of both VAR and PTR are
-     contained within the compilation unit, and that there is no fancy
-     addressing arithmetic associated with any of the types
-     involved.  */
-  if (mem_alias_set != 0 && var_alias_set != 0)
-    {
-      tree ptr_type = TREE_TYPE (ptr);
-      tree var_type = TREE_TYPE (var);
-      
-      /* The star count is -1 if the type at the end of the pointer_to 
-	 chain is not a record or union type. */ 
-      if ((!alias_set_only) && 
-	  ipa_type_escape_star_count_of_interesting_type (var_type) >= 0)
+      /* If the alias sets don't conflict then MEM cannot alias VAR.  */
+      if (!alias_sets_conflict_p (mem_alias_set, var_alias_set))
 	{
-	  int ptr_star_count = 0;
-	  
-	  /* ipa_type_escape_star_count_of_interesting_type is a
-	     little too restrictive for the pointer type, need to
-	     allow pointers to primitive types as long as those types
-	     cannot be pointers to everything.  */
-	  while (POINTER_TYPE_P (ptr_type))
+	  alias_stats.alias_noalias++;
+	  alias_stats.tbaa_resolved++;
+	  return false;
+	}
+
+      /* If VAR is a record or union type, PTR cannot point into VAR
+	 unless there is some explicit address operation in the
+	 program that can reference a field of the type pointed-to by
+	 PTR.  This also assumes that the types of both VAR and PTR
+	 are contained within the compilation unit, and that there is
+	 no fancy addressing arithmetic associated with any of the
+	 types involved.  */
+      if (mem_alias_set != 0 && var_alias_set != 0)
+	{
+	  tree ptr_type = TREE_TYPE (ptr);
+	  tree var_type = TREE_TYPE (var);
+      
+	  /* The star count is -1 if the type at the end of the
+	     pointer_to chain is not a record or union type. */ 
+	  if ((!alias_set_only) && 
+	      ipa_type_escape_star_count_of_interesting_type (var_type) >= 0)
 	    {
-	      /* Strip the *s off.  */ 
-	      ptr_type = TREE_TYPE (ptr_type);
-	      ptr_star_count++;
-	    }
+	      int ptr_star_count = 0;
 	  
-	  /* There does not appear to be a better test to see if the 
-	     pointer type was one of the pointer to everything 
-	     types.  */
-	  if (ptr_star_count > 0)
-	    {
-	      alias_stats.structnoaddress_queries++;
-	      if (ipa_type_escape_field_does_not_clobber_p (var_type, 
-							    TREE_TYPE (ptr))) 
+	      /* ipa_type_escape_star_count_of_interesting_type is a
+		 little too restrictive for the pointer type, need to
+		 allow pointers to primitive types as long as those
+		 types cannot be pointers to everything.  */
+	      while (POINTER_TYPE_P (ptr_type))
+		{
+		  /* Strip the *s off.  */ 
+		  ptr_type = TREE_TYPE (ptr_type);
+		  ptr_star_count++;
+		}
+	  
+	      /* There does not appear to be a better test to see if
+		 the pointer type was one of the pointer to everything
+		 types.  */
+	      if (ptr_star_count > 0)
 		{
+		  alias_stats.structnoaddress_queries++;
+		  if (ipa_type_escape_field_does_not_clobber_p (var_type, 
+								TREE_TYPE (ptr)))
+		    {
+		      alias_stats.structnoaddress_resolved++;
+		      alias_stats.alias_noalias++;
+		      return false;
+		    }
+		}
+	      else if (ptr_star_count == 0)
+		{
+		  /* If PTR_TYPE was not really a pointer to type, it cannot 
+		     alias.  */ 
+		  alias_stats.structnoaddress_queries++;
 		  alias_stats.structnoaddress_resolved++;
 		  alias_stats.alias_noalias++;
 		  return false;
 		}
 	    }
-	  else if (ptr_star_count == 0)
-	    {
-	      /* If PTR_TYPE was not really a pointer to type, it cannot 
-		 alias.  */ 
-	      alias_stats.structnoaddress_queries++;
-	      alias_stats.structnoaddress_resolved++;
-	      alias_stats.alias_noalias++;
-	      return false;
-	    }
 	}
     }