tree.h (TREE_ADDRESSABLE): Document its effect for function types.

	* tree.h (TREE_ADDRESSABLE): Document its effect for function types.
	* calls.c (expand_call): Pass the function type to aggregate_value_p.
	* function.c (aggregate_value_p): Do not honor DECL_BY_REFERENCE on
	the target function of a CALL_EXPR.  Honor TREE_ADDRESSABLE on the
	function type instead.  Reorder and simplify checks.

	* gimplify.c (gimplify_modify_expr_rhs) <WITH_SIZE_EXPR>: New case.
ada/
	* gcc-interface/ada-tree.h (TYPE_RETURNS_UNCONSTRAINED_P): Rename into.
	(TYPE_RETURN_UNCONSTRAINED_P): ...this.
	(TYPE_RETURNS_BY_REF_P): Rename into.
	(TYPE_RETURN_BY_DIRECT_REF_P): ...this.
	(TYPE_RETURNS_BY_TARGET_PTR_P): Delete.
	* gcc-interface/gigi.h (create_subprog_type): Adjust parameter names.
	(build_return_expr): Likewise.
	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Subprogram_Type>:
	Rename local variables.  If the return Mechanism is By_Reference, pass
	return_by_invisible_ref_p to create_subprog_type instead of toggling
	TREE_ADDRESSABLE.  Test return_by_invisible_ref_p in order to annotate
	the mechanism.  Use regular return for contrained types with non-static
	size and return by invisible reference for unconstrained return types
	with default discriminants.  Update comment.
	* gcc-interface/trans.c (Subprogram_Body_to_gnu): If the function
	returns by invisible reference, turn the RESULT_DECL into a pointer.
	Do not handle DECL_BY_REF_P in the CICO case here.
	(call_to_gnu): Remove code handling return by target pointer.  For a
	function call, if the return type has non-constant size, generate the
	assignment with an INIT_EXPR.
	(gnat_to_gnu) <N_Return_Statement>: Remove dead code in the CICO case.
	If the function returns by invisible reference, build the copy return
	operation manually.
	(add_decl_expr): Initialize the variable with an INIT_EXPR.
	* gcc-interface/utils.c (create_subprog_type): Adjust parameter names.
	Adjust for renaming of macros.  Copy the node only when necessary.
	(create_subprog_decl): Do not toggle TREE_ADDRESSABLE on the return
	type, only change DECL_BY_REFERENCE on the RETURN_DECL.
	(convert_from_reference): Delete.
	(is_byref_result): Likewise.
	(gnat_genericize_r): Likewise.
	(gnat_genericize): Likewise.
	(end_subprog_body): Do not call gnat_genericize.
	* gcc-interface/utils2.c (build_binary_op) <INIT_EXPR>: New case.
	(build_return_expr): Adjust parameter names, logic and comment.

From-SVN: r158139

gcc/ChangeLog

+2010-04-08  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* tree.h (TREE_ADDRESSABLE): Document its effect for function types.
+	* calls.c (expand_call): Pass the function type to aggregate_value_p.
+	* function.c (aggregate_value_p): Do not honor DECL_BY_REFERENCE on
+	the target function of a CALL_EXPR.  Honor TREE_ADDRESSABLE on the
+	function type instead.  Reorder and simplify checks.
+
+	* gimplify.c (gimplify_modify_expr_rhs) <WITH_SIZE_EXPR>: New case.
+
 2010-04-08  Jing Yu  <jingyu@google.com>
 	    Zdenek Dvorak  <ook@ucw.cz>
 

gcc/ada/ChangeLog

+2010-04-08  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gcc-interface/ada-tree.h (TYPE_RETURNS_UNCONSTRAINED_P): Rename into.
+	(TYPE_RETURN_UNCONSTRAINED_P): ...this.
+	(TYPE_RETURNS_BY_REF_P): Rename into.
+	(TYPE_RETURN_BY_DIRECT_REF_P): ...this.
+	(TYPE_RETURNS_BY_TARGET_PTR_P): Delete.
+	* gcc-interface/gigi.h (create_subprog_type): Adjust parameter names.
+	(build_return_expr): Likewise.
+	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Subprogram_Type>:
+	Rename local variables.  If the return Mechanism is By_Reference, pass
+	return_by_invisible_ref_p to create_subprog_type instead of toggling
+	TREE_ADDRESSABLE.  Test return_by_invisible_ref_p in order to annotate
+	the mechanism.  Use regular return for contrained types with non-static
+	size and return by invisible reference for unconstrained return types
+	with default discriminants.  Update comment.
+	* gcc-interface/trans.c (Subprogram_Body_to_gnu): If the function
+	returns by invisible reference, turn the RESULT_DECL into a pointer.
+	Do not handle DECL_BY_REF_P in the CICO case here.
+	(call_to_gnu): Remove code handling return by target pointer.  For a
+	function call, if the return type has non-constant size, generate the
+	assignment with an INIT_EXPR.
+	(gnat_to_gnu) <N_Return_Statement>: Remove dead code in the CICO case.
+	If the function returns by invisible reference, build the copy return
+	operation manually.
+	(add_decl_expr): Initialize the variable with an INIT_EXPR.
+	* gcc-interface/utils.c (create_subprog_type): Adjust parameter names.
+	Adjust for renaming of macros.  Copy the node only when necessary.
+	(create_subprog_decl): Do not toggle TREE_ADDRESSABLE on the return
+	type, only change DECL_BY_REFERENCE on the RETURN_DECL.
+	(convert_from_reference): Delete.
+	(is_byref_result): Likewise.
+	(gnat_genericize_r): Likewise.
+	(gnat_genericize): Likewise.
+	(end_subprog_body): Do not call gnat_genericize.
+	* gcc-interface/utils2.c (build_binary_op) <INIT_EXPR>: New case.
+	(build_return_expr): Adjust parameter names, logic and comment.
+
 2010-04-07  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* exp_pakd.adb (Create_Packed_Array_Type): Always use a modular type

gcc/ada/gcc-interface/ada-tree.h

@@ -6,7 +6,7 @@
  *                                                                          *
  *                              C Header File                               *
  *                                                                          *
- *          Copyright (C) 1992-2009, Free Software Foundation, Inc.         *
+ *          Copyright (C) 1992-2010, Free Software Foundation, Inc.         *
  *                                                                          *
  * GNAT is free software;  you can  redistribute it  and/or modify it under *
  * terms of the  GNU General Public License as published  by the Free Soft- *
@@ -90,7 +90,7 @@ do {							    \
 
 /* For FUNCTION_TYPE, nonzero if this denotes a function returning an
    unconstrained array or record.  */
-#define TYPE_RETURNS_UNCONSTRAINED_P(NODE) \
+#define TYPE_RETURN_UNCONSTRAINED_P(NODE) \
   TYPE_LANG_FLAG_1 (FUNCTION_TYPE_CHECK (NODE))
 
 /* For RECORD_TYPE, UNION_TYPE, and QUAL_UNION_TYPE, nonzero if this denotes
@@ -135,8 +135,10 @@ do {							    \
 #define TYPE_CONVENTION_FORTRAN_P(NODE) \
   TYPE_LANG_FLAG_4 (ARRAY_TYPE_CHECK (NODE))
 
-/* For FUNCTION_TYPEs, nonzero if the function returns by reference.  */
-#define TYPE_RETURNS_BY_REF_P(NODE) \
+/* For FUNCTION_TYPEs, nonzero if the function returns by direct reference,
+   i.e. the callee returns a pointer to a memory location it has allocated
+   and the caller only needs to dereference the pointer.  */
+#define TYPE_RETURN_BY_DIRECT_REF_P(NODE) \
   TYPE_LANG_FLAG_4 (FUNCTION_TYPE_CHECK (NODE))
 
 /* For VOID_TYPE, ENUMERAL_TYPE, UNION_TYPE, and RECORD_TYPE, nonzero if this
@@ -148,11 +150,6 @@ do {							    \
     || TREE_CODE (NODE) == UNION_TYPE || TREE_CODE (NODE) == ENUMERAL_TYPE) \
    && TYPE_DUMMY_P (NODE))
 
-/* For FUNCTION_TYPEs, nonzero if function returns by being passed a pointer
-   to a place to store its result.  */
-#define TYPE_RETURNS_BY_TARGET_PTR_P(NODE) \
-  TYPE_LANG_FLAG_5 (FUNCTION_TYPE_CHECK (NODE))
-
 /* For an INTEGER_TYPE, nonzero if TYPE_ACTUAL_BOUNDS is present.  */
 #define TYPE_HAS_ACTUAL_BOUNDS_P(NODE) \
   TYPE_LANG_FLAG_5 (INTEGER_TYPE_CHECK (NODE))

gcc/ada/gcc-interface/decl.c

@@ -6,7 +6,7 @@
  *                                                                          *
  *                          C Implementation File                           *
  *                                                                          *
- *          Copyright (C) 1992-2009, Free Software Foundation, Inc.         *
+ *          Copyright (C) 1992-2010, Free Software Foundation, Inc.         *
  *                                                                          *
  * GNAT is free software;  you can  redistribute it  and/or modify it under *
  * terms of the  GNU General Public License as published  by the Free Soft- *
@@ -3799,13 +3799,13 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 	tree gnu_field_list = NULL_TREE;
 	/* Non-null for subprograms containing parameters passed by copy-in
 	   copy-out (Ada In Out or Out parameters not passed by reference),
-	   in which case it is the list of nodes used to specify the values of
-	   the in out/out parameters that are returned as a record upon
+	   in which case it is the list of nodes used to specify the values
+	   of the In Out/Out parameters that are returned as a record upon
 	   procedure return.  The TREE_PURPOSE of an element of this list is
 	   a field of the record and the TREE_VALUE is the PARM_DECL
 	   corresponding to that field.  This list will be saved in the
 	   TYPE_CI_CO_LIST field of the FUNCTION_TYPE node we create.  */
-	tree gnu_return_list = NULL_TREE;
+	tree gnu_cico_list = NULL_TREE;
 	/* If an import pragma asks to map this subprogram to a GCC builtin,
 	   this is the builtin DECL node.  */
 	tree gnu_builtin_decl = NULL_TREE;
@@ -3831,9 +3831,9 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 	     && Is_Pure (gnat_entity));
 
 	bool volatile_flag = No_Return (gnat_entity);
-	bool returns_by_ref = false;
-	bool returns_unconstrained = false;
-	bool returns_by_target_ptr = false;
+	bool return_by_direct_ref_p = false;
+	bool return_by_invisi_ref_p = false;
+	bool return_unconstrained_p = false;
 	bool has_copy_in_out = false;
 	bool has_stub = false;
 	int parmnum;
@@ -3885,37 +3885,39 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 	if (kind == E_Function || kind == E_Subprogram_Type)
 	  gnu_return_type = gnat_to_gnu_type (Etype (gnat_entity));
 
-	/* If this function returns by reference, make the actual
-	   return type of this function the pointer and mark the decl.  */
+	/* If this function returns by reference, make the actual return
+	   type of this function the pointer and mark the decl.  */
 	if (Returns_By_Ref (gnat_entity))
 	  {
-	    returns_by_ref = true;
 	    gnu_return_type = build_pointer_type (gnu_return_type);
+	    return_by_direct_ref_p = true;
 	  }
 
-	/* If the Mechanism is By_Reference, ensure the return type uses
-	   the machine's by-reference mechanism, which may not the same
-	   as above (e.g., it might be by passing a fake parameter).  */
-	else if (kind == E_Function
-		 && Mechanism (gnat_entity) == By_Reference)
-	  {
-	    TREE_ADDRESSABLE (gnu_return_type) = 1;
-
-	    /* We expect this bit to be reset by gigi shortly, so can avoid a
-	       type node copy here.  This actually also prevents troubles with
-	       the generation of debug information for the function, because
-	       we might have issued such info for this type already, and would
-	       be attaching a distinct type node to the function if we made a
-	       copy here.  */
-	  }
-
-	/* If we are supposed to return an unconstrained array,
-	   actually return a fat pointer and make a note of that.  Return
-	   a pointer to an unconstrained record of variable size.  */
+	/* If the Mechanism is By_Reference, ensure this function uses the
+	   target's by-invisible-reference mechanism, which may not be the
+	   same as above (e.g. it might be passing an extra parameter).
+
+	   Prior to GCC 4, this was handled by just setting TREE_ADDRESSABLE
+	   on the result type.  Everything required to pass by invisible
+	   reference using the target's mechanism (e.g. an extra parameter)
+	   was handled at RTL expansion time.
+
+	   This doesn't work with GCC 4 any more for several reasons.  First,
+	   the gimplification process might need to create temporaries of this
+	   type and the gimplifier ICEs on such attempts; that's why the flag
+	   is now set on the function type instead.  Second, the middle-end
+	   now also relies on a different attribute, DECL_BY_REFERENCE on the
+	   RESULT_DECL, and expects the by-invisible-reference-ness to be made
+	   explicit in the function body.  */
+	else if (kind == E_Function && Mechanism (gnat_entity) == By_Reference)
+	  return_by_invisi_ref_p = true;
+
+	/* If we are supposed to return an unconstrained array, actually return
+	   a fat pointer and make a note of that.  */
 	else if (TREE_CODE (gnu_return_type) == UNCONSTRAINED_ARRAY_TYPE)
 	  {
 	    gnu_return_type = TREE_TYPE (gnu_return_type);
-	    returns_unconstrained = true;
+	    return_unconstrained_p = true;
 	  }
 
 	/* If the type requires a transient scope, the result is allocated
@@ -3924,7 +3926,7 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 	else if (Requires_Transient_Scope (Etype (gnat_entity)))
 	  {
 	    gnu_return_type = build_pointer_type (gnu_return_type);
-	    returns_unconstrained = true;
+	    return_unconstrained_p = true;
 	  }
 
 	/* If the type is a padded type and the underlying type would not
@@ -3936,20 +3938,17 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 		     || Has_Foreign_Convention (gnat_entity)))
 	  gnu_return_type = TREE_TYPE (TYPE_FIELDS (gnu_return_type));
 
-	/* If the return type has a non-constant size, we convert the function
-	   into a procedure and its caller will pass a pointer to an object as
-	   the first parameter when we call the function.  This can happen for
-	   an unconstrained type with a maximum size or a constrained type with
-	   a size not known at compile time.  */
-	if (TYPE_SIZE_UNIT (gnu_return_type)
-	    && !TREE_CONSTANT (TYPE_SIZE_UNIT (gnu_return_type)))
+	/* If the return type is unconstrained, that means it must have a
+	   maximum size.  Use the padded type as the effective return type.
+	   And ensure the function uses the target's by-invisible-reference
+	   mechanism to avoid copying too much data when it returns.  */
+	if (CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_return_type)))
 	  {
-	    returns_by_target_ptr = true;
-	    gnu_param_list
-	      = create_param_decl (get_identifier ("TARGET"),
-				   build_reference_type (gnu_return_type),
-				   true);
-	    gnu_return_type = void_type_node;
+	    gnu_return_type
+	      = maybe_pad_type (gnu_return_type,
+				max_size (TYPE_SIZE (gnu_return_type), true),
+				0, gnat_entity, false, false, false, true);
+	    return_by_invisi_ref_p = true;
 	  }
 
 	/* If the return type has a size that overflows, we cannot have
@@ -4091,8 +4090,8 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 			       &DECL_SOURCE_LOCATION (gnu_field));
 		TREE_CHAIN (gnu_field) = gnu_field_list;
 		gnu_field_list = gnu_field;
-		gnu_return_list = tree_cons (gnu_field, gnu_param,
-					     gnu_return_list);
+		gnu_cico_list
+		  = tree_cons (gnu_field, gnu_param, gnu_cico_list);
 	      }
 	  }
 
@@ -4105,8 +4104,8 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 	/* If we have a CICO list but it has only one entry, we convert
 	   this function into a function that simply returns that one
 	   object.  */
-	if (list_length (gnu_return_list) == 1)
-	  gnu_return_type = TREE_TYPE (TREE_PURPOSE (gnu_return_list));
+	if (list_length (gnu_cico_list) == 1)
+	  gnu_return_type = TREE_TYPE (TREE_PURPOSE (gnu_cico_list));
 
 	if (Has_Stdcall_Convention (gnat_entity))
 	  prepend_one_attribute_to
@@ -4131,22 +4130,25 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 	gnu_param_list = nreverse (gnu_param_list);
 	if (has_stub)
 	  gnu_stub_param_list = nreverse (gnu_stub_param_list);
-	gnu_return_list = nreverse (gnu_return_list);
+	gnu_cico_list = nreverse (gnu_cico_list);
 
 	if (Ekind (gnat_entity) == E_Function)
-	  Set_Mechanism (gnat_entity,
-			 (returns_by_ref || returns_unconstrained
-			  ? By_Reference : By_Copy));
+	  Set_Mechanism (gnat_entity, return_unconstrained_p
+				      || return_by_direct_ref_p
+				      || return_by_invisi_ref_p
+				      ? By_Reference : By_Copy);
 	gnu_type
 	  = create_subprog_type (gnu_return_type, gnu_param_list,
-				 gnu_return_list, returns_unconstrained,
-				 returns_by_ref, returns_by_target_ptr);
+				 gnu_cico_list, return_unconstrained_p,
+				 return_by_direct_ref_p,
+				 return_by_invisi_ref_p);
 
 	if (has_stub)
 	  gnu_stub_type
 	    = create_subprog_type (gnu_return_type, gnu_stub_param_list,
-				   gnu_return_list, returns_unconstrained,
-				   returns_by_ref, returns_by_target_ptr);
+				   gnu_cico_list, return_unconstrained_p,
+				   return_by_direct_ref_p,
+				   return_by_invisi_ref_p);
 
 	/* A subprogram (something that doesn't return anything) shouldn't
 	   be considered const since there would be no reason for such a

gcc/ada/gcc-interface/gigi.h

@@ -6,7 +6,7 @@
  *                                                                          *
  *                              C Header File                               *
  *                                                                          *
- *          Copyright (C) 1992-2009, Free Software Foundation, Inc.         *
+ *          Copyright (C) 1992-2010, Free Software Foundation, Inc.         *
  *                                                                          *
  * GNAT is free software;  you can  redistribute it  and/or modify it under *
  * terms of the  GNU General Public License as published  by the Free Soft- *
@@ -545,19 +545,19 @@ extern void add_parallel_type (tree decl, tree parallel_type);
 /* Return the parallel type associated to a type, if any.  */
 extern tree get_parallel_type (tree type);
 
-/* Returns a FUNCTION_TYPE node. RETURN_TYPE is the type returned by the
-   subprogram. If it is void_type_node, then we are dealing with a procedure,
-   otherwise we are dealing with a function. PARAM_DECL_LIST is a list of
-   PARM_DECL nodes that are the subprogram arguments.  CICO_LIST is the
-   copy-in/copy-out list to be stored into TYPE_CI_CO_LIST.
-   RETURNS_UNCONSTRAINED is true if the function returns an unconstrained
-   object.  RETURNS_BY_REF is true if the function returns by reference.
-   RETURNS_BY_TARGET_PTR is true if the function is to be passed (as its
-   first parameter) the address of the place to copy its result.  */
+/* Return a FUNCTION_TYPE node.  RETURN_TYPE is the type returned by the
+   subprogram.  If it is VOID_TYPE, then we are dealing with a procedure,
+   otherwise we are dealing with a function.  PARAM_DECL_LIST is a list of
+   PARM_DECL nodes that are the subprogram parameters.  CICO_LIST is the
+   copy-in/copy-out list to be stored into the TYPE_CICO_LIST field.
+   RETURN_UNCONSTRAINED_P is true if the function returns an unconstrained
+   object.  RETURN_BY_DIRECT_REF_P is true if the function returns by direct
+   reference.  RETURN_BY_INVISI_REF_P is true if the function returns by
+   invisible reference.  */
 extern tree create_subprog_type (tree return_type, tree param_decl_list,
-                                 tree cico_list, bool returns_unconstrained,
-                                 bool returns_by_ref,
-                                 bool returns_by_target_ptr);
+				 tree cico_list, bool return_unconstrained_p,
+				 bool return_by_direct_ref_p,
+				 bool return_by_invisi_ref_p);
 
 /* Return a copy of TYPE, but safe to modify in any way.  */
 extern tree copy_type (tree type);
@@ -804,7 +804,7 @@ extern tree build_cond_expr (tree result_type, tree condition_operand,
                              tree true_operand, tree false_operand);
 
 /* Similar, but for RETURN_EXPR.  */
-extern tree build_return_expr (tree result_decl, tree ret_val);
+extern tree build_return_expr (tree ret_obj, tree ret_val);
 
 /* Build a CALL_EXPR to call FUNDECL with one argument, ARG.  Return
    the CALL_EXPR.  */

gcc/ada/gcc-interface/utils2.c

@@ -6,7 +6,7 @@
  *                                                                          *
  *                          C Implementation File                           *
  *                                                                          *
- *          Copyright (C) 1992-2009, Free Software Foundation, Inc.         *
+ *          Copyright (C) 1992-2010, Free Software Foundation, Inc.         *
  *                                                                          *
  * GNAT is free software;  you can  redistribute it  and/or modify it under *
  * terms of the  GNU General Public License as published  by the Free Soft- *
@@ -609,6 +609,7 @@ build_binary_op (enum tree_code op_code, tree result_type,
 
   switch (op_code)
     {
+    case INIT_EXPR:
     case MODIFY_EXPR:
       /* If there were integral or pointer conversions on the LHS, remove
 	 them; we'll be putting them back below if needed.  Likewise for
@@ -1397,45 +1398,40 @@ build_cond_expr (tree result_type, tree condition_operand,
   return result;
 }
 
-/* Similar, but for RETURN_EXPR.  If RESULT_DECL is non-zero, build
-   a RETURN_EXPR around the assignment of RET_VAL to RESULT_DECL.
-   If RESULT_DECL is zero, build a bare RETURN_EXPR.  */
+/* Similar, but for RETURN_EXPR.  If RET_VAL is non-null, build a RETURN_EXPR
+   around the assignment of RET_VAL to RET_OBJ.  Otherwise just build a bare
+   RETURN_EXPR around RESULT_OBJ, which may be null in this case.  */
 
 tree
-build_return_expr (tree result_decl, tree ret_val)
+build_return_expr (tree ret_obj, tree ret_val)
 {
   tree result_expr;
 
-  if (result_decl)
+  if (ret_val)
     {
       /* The gimplifier explicitly enforces the following invariant:
 
-           RETURN_EXPR
-               |
-           MODIFY_EXPR
-           /        \
-          /          \
-      RESULT_DECL    ...
+	      RETURN_EXPR
+		  |
+	      MODIFY_EXPR
+	      /        \
+	     /          \
+	 RET_OBJ        ...
 
-      As a consequence, type-homogeneity dictates that we use the type
-      of the RESULT_DECL as the operation type.  */
-
-      tree operation_type = TREE_TYPE (result_decl);
-
-      /* Convert the right operand to the operation type.  Note that
-         it's the same transformation as in the MODIFY_EXPR case of
-         build_binary_op with the additional guarantee that the type
-         cannot involve a placeholder, since otherwise the function
-         would use the "target pointer" return mechanism.  */
+	 As a consequence, type consistency dictates that we use the type
+	 of the RET_OBJ as the operation type.  */
+      tree operation_type = TREE_TYPE (ret_obj);
 
+      /* Convert the right operand to the operation type.  Note that it's the
+	 same transformation as in the MODIFY_EXPR case of build_binary_op,
+	 with the assumption that the type cannot involve a placeholder.  */
       if (operation_type != TREE_TYPE (ret_val))
 	ret_val = convert (operation_type, ret_val);
 
-      result_expr
-	= build2 (MODIFY_EXPR, operation_type, result_decl, ret_val);
+      result_expr = build2 (MODIFY_EXPR, operation_type, ret_obj, ret_val);
     }
   else
-    result_expr = NULL_TREE;
+    result_expr = ret_obj;
 
   return build1 (RETURN_EXPR, void_type_node, result_expr);
 }

gcc/calls.c

@@ -2089,7 +2089,7 @@ expand_call (tree exp, rtx target, int ignore)
   /* Set up a place to return a structure.  */
 
   /* Cater to broken compilers.  */
-  if (aggregate_value_p (exp, (!fndecl ? fntype : fndecl)))
+  if (aggregate_value_p (exp, fntype))
     {
       /* This call returns a big structure.  */
       flags &= ~(ECF_CONST | ECF_PURE | ECF_LOOPING_CONST_OR_PURE);

gcc/function.c

@@ -1853,41 +1853,36 @@ struct rtl_opt_pass pass_instantiate_virtual_regs =
 int
 aggregate_value_p (const_tree exp, const_tree fntype)
 {
+  const_tree type = (TYPE_P (exp)) ? exp : TREE_TYPE (exp);
   int i, regno, nregs;
   rtx reg;
 
-  const_tree type = (TYPE_P (exp)) ? exp : TREE_TYPE (exp);
-
-  /* DECL node associated with FNTYPE when relevant, which we might need to
-     check for by-invisible-reference returns, typically for CALL_EXPR input
-     EXPressions.  */
-  const_tree fndecl = NULL_TREE;
-
   if (fntype)
     switch (TREE_CODE (fntype))
       {
       case CALL_EXPR:
-	fndecl = get_callee_fndecl (fntype);
-	fntype = (fndecl
-		  ? TREE_TYPE (fndecl)
-		  : TREE_TYPE (TREE_TYPE (CALL_EXPR_FN (fntype))));
+	{
+	  tree fndecl = get_callee_fndecl (fntype);
+	  fntype = (fndecl
+		    ? TREE_TYPE (fndecl)
+		    : TREE_TYPE (TREE_TYPE (CALL_EXPR_FN (fntype))));
+	}
 	break;
       case FUNCTION_DECL:
-	fndecl = fntype;
-	fntype = TREE_TYPE (fndecl);
+	fntype = TREE_TYPE (fntype);
 	break;
       case FUNCTION_TYPE:
       case METHOD_TYPE:
         break;
       case IDENTIFIER_NODE:
-	fntype = 0;
+	fntype = NULL_TREE;
 	break;
       default:
-	/* We don't expect other rtl types here.  */
+	/* We don't expect other tree types here.  */
 	gcc_unreachable ();
       }
 
-  if (TREE_CODE (type) == VOID_TYPE)
+  if (VOID_TYPE_P (type))
     return 0;
 
   /* If a record should be passed the same as its first (and only) member
@@ -1901,24 +1896,21 @@ aggregate_value_p (const_tree exp, const_tree fntype)
       && DECL_BY_REFERENCE (exp))
     return 1;
 
-  /* If the EXPression is a CALL_EXPR, honor DECL_BY_REFERENCE set on the
-     called function RESULT_DECL, meaning the function returns in memory by
-     invisible reference.  This check lets front-ends not set TREE_ADDRESSABLE
-     on the function type, which used to be the way to request such a return
-     mechanism but might now be causing troubles at gimplification time if
-     temporaries with the function type need to be created.  */
-  if (TREE_CODE (exp) == CALL_EXPR && fndecl && DECL_RESULT (fndecl)
-      && DECL_BY_REFERENCE (DECL_RESULT (fndecl)))
+  /* Function types that are TREE_ADDRESSABLE force return in memory.  */
+  if (fntype && TREE_ADDRESSABLE (fntype))
     return 1;
 
-  if (targetm.calls.return_in_memory (type, fntype))
-    return 1;
   /* Types that are TREE_ADDRESSABLE must be constructed in memory,
      and thus can't be returned in registers.  */
   if (TREE_ADDRESSABLE (type))
     return 1;
+
   if (flag_pcc_struct_return && AGGREGATE_TYPE_P (type))
     return 1;
+
+  if (targetm.calls.return_in_memory (type, fntype))
+    return 1;
+
   /* Make sure we have suitable call-clobbered regs to return
      the value in; if not, we must return it in memory.  */
   reg = hard_function_value (type, 0, fntype, 0);
@@ -1933,6 +1925,7 @@ aggregate_value_p (const_tree exp, const_tree fntype)
   for (i = 0; i < nregs; i++)
     if (! call_used_regs[regno + i])
       return 1;
+
   return 0;
 }
 

gcc/gimplify.c

@@ -4278,6 +4278,18 @@ gimplify_modify_expr_rhs (tree *expr_p, tree *from_p, tree *to_p,
 	ret = GS_UNHANDLED;
 	break;
 
+      case WITH_SIZE_EXPR:
+	/* Likewise for calls that return an aggregate of non-constant size,
+	   since we would not be able to generate a temporary at all.  */
+	if (TREE_CODE (TREE_OPERAND (*from_p, 0)) == CALL_EXPR)
+	  {
+	    *from_p = TREE_OPERAND (*from_p, 0);
+	    ret = GS_OK;
+	  }
+	else
+	  ret = GS_UNHANDLED;
+	break;
+
 	/* If we're initializing from a container, push the initialization
 	   inside it.  */
       case CLEANUP_POINT_EXPR:

gcc/tree.h

@@ -1110,9 +1110,10 @@ extern void omp_clause_range_check_failed (const_tree, const char *, int,
    In CONSTRUCTOR nodes, it means object constructed must be in memory.
    In LABEL_DECL nodes, it means a goto for this label has been seen
    from a place outside all binding contours that restore stack levels.
-   In ..._TYPE nodes, it means that objects of this type must
-   be fully addressable.  This means that pieces of this
-   object cannot go into register parameters, for example.
+   In ..._TYPE nodes, it means that objects of this type must be fully
+   addressable.  This means that pieces of this object cannot go into
+   register parameters, for example.  If this a function type, this
+   means that the value must be returned in memory.
    In IDENTIFIER_NODEs, this means that some extern decl for this name
    had its address taken.  That matters for inline functions.  */
 #define TREE_ADDRESSABLE(NODE) ((NODE)->base.addressable_flag)