call.c (build_call): Still evaluate the actual argument.

	* call.c (build_call): Still evaluate the actual argument.
	* class.c (is_empty_class): Update for -fnew-abi.
	* decl2.c: -fnew-abi implies -fsquangle.
	* method.c (do_build_assign_ref): Don't do anything to copy
	an empty class.
	(do_build_copy_constructor): Likewise.
	* call.c (build_over_call): Likewise.

From-SVN: r19029

gcc/cp/ChangeLog

+Mon Apr  6 02:25:05 1998  Jason Merrill  <jason@yorick.cygnus.com>
+
+	* call.c (build_call): Still evaluate the actual argument.
+	* class.c (is_empty_class): Update for -fnew-abi.
+
+	* decl2.c: -fnew-abi implies -fsquangle.
+
+	* method.c (do_build_assign_ref): Don't do anything to copy
+	an empty class.
+	(do_build_copy_constructor): Likewise.
+	* call.c (build_over_call): Likewise.
+
 Sat Apr  4 18:43:58 1998  Jason Merrill  <jason@yorick.cygnus.com>
 
 	* tree.c (avoid_overlap): Return a value.

gcc/cp/call.c

@@ -525,7 +525,8 @@ build_call (function, result_type, parms)
 	  TREE_TYPE (t) = TREE_TYPE (TREE_VALUE (tmp));
 	  RTL_EXPR_RTL (t) = const0_rtx;
 	  RTL_EXPR_SEQUENCE (t) = NULL_RTX;
-	  TREE_VALUE (tmp) = t;
+	  TREE_VALUE (tmp) = build (COMPOUND_EXPR, TREE_TYPE (t),
+				    TREE_VALUE (tmp), t);
 	}
 
   function = build_nt (CALL_EXPR, function, parms, NULL_TREE);
@@ -3351,6 +3352,12 @@ build_over_call (fn, convs, args, flags)
 	{
 	  tree to = stabilize_reference
 	    (build_indirect_ref (TREE_VALUE (args), 0));
+
+	  /* Don't copy the padding byte; it might not have been allocated
+	     if to is a base subobject.  */
+	  if (is_empty_class (DECL_CLASS_CONTEXT (fn)))
+	    return to;
+
 	  val = build (INIT_EXPR, DECL_CONTEXT (fn), to, arg);
 	  TREE_SIDE_EFFECTS (val) = 1;
 	  return build_unary_op (ADDR_EXPR, val, 0);
@@ -3358,10 +3365,16 @@ build_over_call (fn, convs, args, flags)
     }
   else if (DECL_NAME (fn) == ansi_opname[MODIFY_EXPR]
 	   && copy_args_p (fn)
-	   && TYPE_HAS_TRIVIAL_ASSIGN_REF (DECL_CONTEXT (fn)))
+	   && TYPE_HAS_TRIVIAL_ASSIGN_REF (DECL_CLASS_CONTEXT (fn)))
     {
       tree to = stabilize_reference
 	(build_indirect_ref (TREE_VALUE (converted_args), 0));
+
+      /* Don't copy the padding byte; it might not have been allocated
+	 if to is a base subobject.  */
+      if (is_empty_class (DECL_CLASS_CONTEXT (fn)))
+	return to;
+
       arg = build_indirect_ref (TREE_VALUE (TREE_CHAIN (converted_args)), 0);
       val = build (MODIFY_EXPR, TREE_TYPE (to), to, arg);
       TREE_SIDE_EFFECTS (val) = 1;

gcc/cp/class.c

@@ -5486,7 +5486,13 @@ is_empty_class (type)
 {
   tree t;
 
-  if (! IS_AGGR_TYPE (type) || TYPE_BINFO_BASETYPES (type))
+  if (! IS_AGGR_TYPE (type))
+    return 0;
+
+  if (flag_new_abi)
+    return CLASSTYPE_SIZE (type) == integer_zero_node;
+
+  if (TYPE_BINFO_BASETYPES (type))
     return 0;
   t = TYPE_FIELDS (type);
   while (t && TREE_CODE (t) != FIELD_DECL)

gcc/cp/decl2.c

@@ -401,7 +401,9 @@ int flag_new_for_scope = 1;
 
 int flag_weak = 1;
 
-int flag_new_abi = 1;
+/* Nonzero to enable experimental ABI changes.  */
+
+int flag_new_abi;
 
 /* Maximum template instantiation depth. Must be at least 17 for ANSI
    compliance. */
@@ -469,8 +471,7 @@ static struct { char *string; int *variable; int on_value;} lang_f_options[] =
   {"check-new", &flag_check_new, 1},
   {"repo", &flag_use_repository, 1},
   {"for-scope", &flag_new_for_scope, 2},
-  {"weak", &flag_weak, 1},
-  {"new-abi", &flag_new_abi, 1}
+  {"weak", &flag_weak, 1}
 };
 
 /* Decode the string P as a language-specific option.
@@ -562,6 +563,16 @@ lang_decode_option (p)
 	  error ("-fno-ansi-overloading is no longer supported");
 	  found = 1;
 	}
+      else if (!strcmp (p, "new-abi"))
+	{
+	  flag_new_abi = 1;
+	  flag_do_squangling = 1;
+	}
+      else if (!strcmp (p, "no-new-abi"))
+	{
+	  flag_new_abi = 0;
+	  flag_do_squangling = 0;
+	}
       else if (!strncmp (p, "template-depth-", 15))
 	{
 	  char *endp = p + 15;

gcc/cp/method.c

@@ -2047,7 +2047,11 @@ do_build_copy_constructor (fndecl)
     parm = TREE_CHAIN (parm);
   parm = convert_from_reference (parm);
 
-  if (TYPE_HAS_TRIVIAL_INIT_REF (current_class_type))
+  if (TYPE_HAS_TRIVIAL_INIT_REF (current_class_type)
+      && is_empty_class (current_class_type))
+    /* Don't copy the padding byte; it might not have been allocated
+       if *this is a base subobject.  */;
+  else if (TYPE_HAS_TRIVIAL_INIT_REF (current_class_type))
     {
       t = build (INIT_EXPR, void_type_node, current_class_ref, parm);
       TREE_SIDE_EFFECTS (t) = 1;
@@ -2159,7 +2163,11 @@ do_build_assign_ref (fndecl)
 
   parm = convert_from_reference (parm);
 
-  if (TYPE_HAS_TRIVIAL_ASSIGN_REF (current_class_type))
+  if (TYPE_HAS_TRIVIAL_ASSIGN_REF (current_class_type)
+      && is_empty_class (current_class_type))
+    /* Don't copy the padding byte; it might not have been allocated
+       if *this is a base subobject.  */;
+  else if (TYPE_HAS_TRIVIAL_ASSIGN_REF (current_class_type))
     {
       tree t = build (MODIFY_EXPR, void_type_node, current_class_ref, parm);
       TREE_SIDE_EFFECTS (t) = 1;