exp_ch4.adb (Expand_Allocator_Expression): When an initialized allocator's designated type is a class-wide type...

2005-06-14  Gary Dismukes  <dismukes@adacore.com>
	    Javier Miranda  <miranda@adacore.com>
	    Ed Schonberg  <schonberg@adacore.com>
	    Hristian Kirtchev  <kirtchev@adacore.com>

	* exp_ch4.adb (Expand_Allocator_Expression): When an initialized
	allocator's designated type is a class-wide type, and compiling for
	Ada 2005, emit a run-time check that the accessibility level of the
	type given in the allocator's expression is not deeper than the level
	of the allocator's access type.

	(Tagged_Membership): Modified to gives support to abstract interface
	types.

	* a-tags.ads, a-tags.adb (type Type_Specific_Data): Add component
	Access_Level.
	(Descendant_Tag): New predefined function
	(Is_Descendant_At_Same_Level): New predefined function
	(Get_Access_Level): New private function
	(Set_Access_Level): New private procedure
	(IW_Membership): New function. Given the tag of an object and the tag
	associated with an interface, evaluate if the object implements the
	interface.
	(Register_Interface_Tag): New procedure used to initialize the table of
	interfaces used by the IW_Membership function.
	(Set_Offset_To_Top): Initialize the Offset_To_Top field in the prologue
	of the dispatch table.
	(Inherit_TSD): Modified to copy the table of ancestor tags plus the
	table of interfaces of the parent.
	(Expanded_Name): Raise Tag_Error if the passed tag equals No_Tag.
	(External_Tag): Raise Tag_Error if the passed tag equals No_Tag.
	(Parent_Tag): Return No_Tag in the case of a root-level tagged type,
	and raise Tag_Error if the passed tag equalis No_Tag, to conform with
	Ada 2005 semantics for the new predefined function.

	* exp_attr.adb (Expand_N_Attribute, case Attribute_Input): Generate
	call to Descendant_Tag rather than Internal_Tag.
	(Expand_N_Attribute, case Attribute_Output): Emit a check to ensure that
	the accessibility level of the attribute's Item parameter is not deeper
	than the level of the attribute's prefix type. Tag_Error is raised if
	the check fails. The check is only emitted for Ada_05.
	(Find_Stream_Subprogram): If a TSS exists on the type itself for the
	requested stream attribute, use it.
	(Expand_N_Attribute_Reference): If the designated type is an interface
	then rewrite the referenced object as a conversion to force the
	displacement of the pointer to the secondary dispatch table.
	(Expand_N_Attribute_Reference, case 'Constrained): Return false if this
	is a dereference of an object with a constrained partial view.

	* exp_ch5.adb (Expand_N_Return_Statement): When a function's result
	type is a class-wide type, emit a run-time check that the accessibility
	level of the returned object is not deeper than the level of the
	function's master (only when compiling for Ada 2005).

	* exp_disp.ads, exp_disp.adb (Ada_Actions, Action_Is_Proc,
	Action_Nb_Arg): Add entries for new Get_Access_Level and
	Set_Access_Level routines in these tables.
	(Make_DT): Generate a call to set the accessibility level of the
	tagged type in its TSD.
	(Make_DT): Code cleanup. The functionality of generating all the
	secondary dispatch tables has been moved to freeze_record_type.
	(Make_Abstract_Interface_DT): Minor code cleanup.
	(Set_All_DT_Position): Code cleanup. As part of the code cleanup
	this subprogram implements a new algorithm that provides the
	same functionality and it is more clear in case of primitives
	associated with abstract interfaces.
	(Set_All_Interfaces_DTC_Entity): Removed. As part of the code
	clean up, the functionality of this subprogram is now provided
	by Set_All_DT_Position.
	(Write_DT): New subprogram: a debugging procedure designed to be called
	within gdb to display the dispatch tables associated with a tagged
	type.
	(Collect_All_Interfaces): New subprogram that collects the whole list
	of interfaces that are directly or indirectly implemented by a tagged
	type.
	(Default_Prim_Op_Position): New subprogram that returns the fixed
	position in the dispatch table of the default primitive operations.
	(Expand_Interface_Actuals): New subprogram to generate code that
	displaces all the actuals corresponding to class-wide interfaces to
	reference the interface tag of the actual object.
	(Expand_Interface_Conversion): New subprogram. Reference the base of
	the object to give access to the interface tag associated with the
	secondary dispatch table.
	(Expand_Interface_Thunk): New subprogram that generates the code of the
	thunk. This is required for compatibility with the C+ ABI.
	(Make_Abstract_Interface_DT): New subprogram that generate the
	declarations for the secondary dispatch tables associated with an
	abstract interface.
	(Set_All_Interfaces_DTC_Entity): New subprogram that sets the DTC_Entity
	attribute for each primitive operation covering interface subprograms
	(Expand_Dispatching_Call, Fill_DT_Entry, Make_DT, Set_All_DT_Position):
	These subprograms were upgraded to give support to abstract interfaces

	* rtsfind.ads (type RE_Id): Add RE_Descendant_Tag,
	RE_Is_Descendant_At_Same_Level, RE_Get_Access_Level, and
	RE_Set_Access_Level.
	(RE_Unit_Table): Add entries for new Ada.Tags operations.
	Add support to call the followig new run-time subprograms:
	IW_Membership, Register_Interface_Tag, and Set_Offset_To_Top

	* sem_ch3.adb (Constant_Redeclaration): Allow a deferred constant to
	match its full declaration when both have an access definition with
	statically matching designated subtypes.
	(Analyze_Component_Declaration): Delete commented out code that was
	incorrectly setting the scope of an anonymous access component's type.
	(Process_Discriminants): Set Is_Local_Anonymous_Access for the type of
	an access discriminant when the containing type is nonlimited.
	(Make_Incomplete_Type_Declaration): Create an incomplete type
	declaration for a record type that includes self-referential access
	components.
	(Check_Anonymous_Access_Types): Before full analysis of a record type
	declaration, create anonymous access types for each self-referential
	access component.
	(Analyze_Component_Declaration, Array_Type_Declaration): Indicate that
	an access component in this context is a Local_Anonymous_Access, for
	proper accessibility checks.
	(Access_Definition): Set properly the scope of the anonymous access type
	created for a stand-alone access object.
	(Find_Type_Of_Object): An object declaration may be given with an access
	definition.
	(Complete_Subprograms_Derivation): New subprogram used to complete
	type derivation of private tagged types implementing interfaces.
	In this case some interface primitives may have been overriden
	with the partial-view and, instead of re-calculating them, they
	are included in the list of primitive operations of the full-view.
	(Build_Derived_Record_Type): Modified to give support to private
	types implemening interfaces.
	(Access_Definition): Reject ALL on anonymous access types.
	(Build_Derived_Record_Type): In the case of Ada 2005, allow a tagged
	type derivation to occur at a deeper accessibility level than the
	parent type.
	For the case of derivation within a generic body however, disallow the
	derivation if the derived type has an ancestor that is a formal type
	declared in the formal part of an enclosing generic.
	(Analyze_Object_Declaration): For protected objects, remove the check
	that they cannot contain interrupt handlers if not declared at library
	level.
	(Add_Interface_Tag_Components): New subprogram to add the tag components
	corresponding to all the abstract interface types implemented by a
	record type or a derived record type.
	(Analyze_Private_Extension_Declaration, Build_Derived_Record_Type,
	Derived_Type_Declaration, Find_Type_Name, Inherit_Components,
	Process_Full_View, Record_Type_Declaration): Modified to give
	support to abstract interface types
	(Collect_Interfaces): New subprogram that collects the list of
	interfaces that are not already implemented by the ancestors
	(Process_Full_View): Set flag Has_Partial_Constrained_View appropriately
	when partial view has no discriminants and full view has defaults.
	(Constrain_Access): Reject a constraint on a general access type
	if the discriminants of the designated type have defaults.
	(Access_Subprogram_Declaration): Associate the Itype node with the inner
	full-type declaration or subprogram spec. This is required to handle
	nested anonymous declarations.
	(Analyze_Private_Extension_Declaration, Build_Derived_Record_Type,
	Derived_Type_Declaration, Find_Type_Name, Inherit_Components,
	Process_Full_View, Record_Type_Declaration): Modified to give
	support to abstract interface types
	(Derive_Subprograms): Addition of a new formal to indicate if
	we are in the case of an abstact-interface derivation
	(Find_Type_Of_Subtype_Indic): Moved from the body of the package
	to the specification because it is requied to analyze all the
	identifiers found in a list of interfaces

	* debug.adb: Complete documentation of flag "-gnatdZ"

	* exp_ch3.adb: Implement config version of persistent_bss pragma
	(Check_Stream_Attributes): Use Stream_Attribute_Available instead of
	testing for TSS presence to properly enforce visibility rules.
	(Freeze_Record_Type): Code cleanup. Modified to call the subprogram
	Make_Abstract_Interfaces_DT to generate the secondary tables
	associated with abstract interfaces.
	(Build_Init_Procedure): Modified to initialize all the tags
	corresponding.
	(Component_Needs_Simple_Initialization): Similar to other tags,
	interface tags do not need initialization.
	(Freeze_Record_Type): Modified to give support to abstract interface
	types.
	(Expand_N_Object_Declaration): Do not generate an initialization for
	a scalar temporary marked as internal.

	* exp_ch6.adb (Add_Simple_Call_By_Copy_Code): Handle properly an
	in-out parameter that is a component in an initialization procedure,
	whose constraint might depend on discriminants, and that may be
	misaligned because of packing or representation clauses.
	(Is_Legal_Copy): New predicate to determine whether a possibly
	misaligned in-out actual can actually be passed by copy/return. This
	is an error in case the type is by_reference, and a warning if this is
	the consequence of a DEC import pragma on the subprogram.
	(Expand_Call, Freeze_Subprogram): Modified to give support to abstract
	interface types
	(Expand_Inlined_Call): Mark temporary generated for the return value as
	internal, so that no useless scalar normalization is generated for it.
	(Expand_N_Subprogram_Declaration): Save unanalyzed body so calls to
	null procedure can always be inlined.
	(Expand_N_Subprogram_Declaration): If this is the declaration of a null
	procedure, generate an explicit empty body for it.

	* exp_util.ads, exp_util.adb (Find_Interface_ADT): New subprogram.
	Given a type implementing an interface, returns the corresponding
	access_disp_table value.
	(Find_Interface_Tag): New subprogram. Given a type implementing an
	interface, returns the record component containing the tag of the
	interface.
	(Find_Interface_Tag): New overloaded subprogram. Subsidiary to the
	previous ones that return the corresponding tag and access_disp_table
	entities.
	(Is_Predefined_Dispatching_Operation): Determines if a subprogram
	is a predefined primitive operation.
	(Expand_Subtype_From_Expr): If the expression is a selected component
	within an initialization procedure, compute its actual subtype, because
	the component may depend on the discriminants of the enclosing record.

	* i-cpp.ads, i-cpp.adb:
	This package has been left available for compatibility with previous
	versions of the frontend. As part of the new layout this is now a
	dummy package that uses declarations available at a-tags.ads

	* par-ch3.adb (P_Identifier_Declarations): Give an error for use of
	"constant access" and "aliased [constant] access" when not compiling
	with -gnat05.
	Suppress Ada 2005 keyword warning if -gnatwY used
	(P_Identifier_Declarations): Add support for object declarations with
	access definitions.
	(Private_Extension_Declaration): Complete the documentation
	(P_Derived_Type_Def_Or_Private_Ext_Decl): Fill the inteface_list
	attribute in case of private extension declaration
	(P_Type_Declaration): Mark as "abstract" the type declarations
	corresponding with protected, synchronized and task interfaces
	(P_Declarative_Items): "not" and "overriding" are overriding indicators
	for a subprogram or instance declaration.

	* sem_ch12.adb (Analyze_Subprogram_Instantiation): Verify that an
	instantiation that is a dispatching operation has controlling access
	parameters that are null excluding.
	Save and restore Ada_Version_Explicit, for implementation of AI-362
	(Validate_Derived_Type_Instance): Add check for abstract interface
	types.
	(Analyze_Formal_Package): Establish Instantiation source for the copy of
	the generic that is created to represent the formal package.
	(Analyze_Package_Instantiation): Instantiate body immediately if the
	package is a predefined unit that contains inlined subprograms, and
	we are compiling for a Configurable_Run_Time.
	(Instantiate_Formal_Subprogram): Indicate that null default subprogram
	If the program has a null default, generate an empty body for it.

	* sem_ch6.adb, sem_ch9.adb (Analyze_Subprograms_Declaration): Update
	error message condition, null procedures are correctly detected now.
	(New_Overloaded_Entity): Bypass trivial overriding indicator check
	for subprograms in the context of protected types. Instead, the
	indicator is examined in Sem_Ch9 while analysing the subprogram
	declaration.
	(Check_Overriding_Indicator): Check consistency of overriding indicator
	on subprogram stubs as well.
	(Analyze_Subprogram_Declaration): Diagnose null procedures declared at
	the library level.
	(Analize_Subprogram_Specification): When analyzing a subprogram in which
	the type of the first formal is a concurrent type, replace this type
	by the corresponding record type.
	(Analyze_Subprogram_Body): Undo the previous work.
	(Analyze_Procedure_Call): If the call has the form Object.Op, the
	analysis of the prefix ends up analyzing the call itself, after which
	we are done.
	(Has_Interface_Formals): New subprogram subsidiary to analyze
	subprogram_specification that returns true if some non
	class-wide interface subprogram is found
	(New_Overloaded_Entity): Modified to give support to abstract
	interface types
	(Conforming_Types): In Ada 2005 mode, conformance checking of anonymous
	access to subprograms must be recursive.
	(Is_Unchecked_Conversion): Improve the test that recognizes
	instantiations of Unchecked_Conversion, and allows them in bodies that
	are to be inlined by the front-end. When the body comes from an
	instantiation, a reference to Unchecked_Conversion will be an
	Expanded_Name, even though the body has not been analyzed yet.
	Replace Is_Overriding and Not_Overriding in subprogram_indication with
	Must_Override and Must_Not_Override, to better express intent of AI.
	(Analyze_Subprogram_Body): If an overriding indicator is given, check
	that it is consistent with the overrinding status of the subprogram
	at this point.
	(Analyze_Subprogram_Declaration): Indicate that a null procedure is
	always inlined.
	If the subprogram is a null procedure, indicate that it does not need
	a completion.

	* sem_disp.adb (Check_Controlling_Type): Give support to entities
	available through limited-with clauses.
	(Check_Dispatching_Operation): A stub acts like a body, and therefore is
	allowed as the last primitive of a tagged type if it has no previous
	spec.
	(Override_Dispatching_Operation, Check_Dispatching_Operation): Modified
	to give support to abstract interface types

	* sem_res.adb (Valid_Conversion): Perform an accessibility level check
	in the case where the target type is an anonymous access type of an
	object or component (that is, when Is_Local_Anonymous_Access is true).
	Prevent the special checks for conversions of access discriminants in
	the case where the discriminant belongs to a nonlimited type, since
	such discriminants have their accessibility level defined in the same
	way as a normal component of an anonymous access type.
	(Resolve_Allocator): When an allocator's designated type is a class-wide
	type, check that the accessibility level of type given in the
	allocator's expression or subtype indication is not statically deeper
	than the level of the allocator's access type.
	(Check_Discriminant_Use): Diagnose discriminant given by an expanded
	name in a discriminant constraint of a record component.
	(Resolve_Explicit_Dereference): Do not check whether the type is
	incomplete when the dereference is a use of an access discriminant in
	an initialization procedure.
	(Resolve_Type_Conversion): Handle conversions to abstract interface
	types.
	(Valid_Tagged_Conversion): The conversion of a tagged type to an
	abstract interface type is always valid.
	(Valid_Conversion): Modified to give support to abstract interface types
	(Resolve_Actuals): Enable full error reporting on view conversions
	between unrelated by_reference array types.
	The rule for view conversions of arrays with aliased components is
	weakened in Ada 2005.
	Call to obsolescent subprogram is now considered to be a violation of
	pragma Restrictions (No_Obsolescent_Features).
	(Check_Direct_Boolean_Operator): If the boolean operation has been
	constant-folded, there is nothing to check.
	(Resolve_Comparison_Op, Resolve_Equality_Op, Resolve_Boolean_Op): Defer
	check on possible violation of restriction No_Direct_Boolean_Operators
	until after expansion of operands, to prevent spurious errors when
	operation is constant-folded.

	* sem_type.ads, sem_type.adb (Covers, Intersect_Types, Specific_Type,
	Has_Compatible_Type): Modified to give support to abstract interface
	types.
	(Interface_Present_In_Ancestor): New function to theck if some ancestor
	of a given type implements a given interface

	* sem_ch4.adb (Analyze_Call): Handle properly an indirect call whose
	prefix is a parameterless function that returns an access_to_procedure.
	(Transform_Object_Operation): Handle properly function calls of the
	form Obj.Op (X), which prior to analysis appear as indexed components.
	(Analyze_One_Call): Complete the error notification to help new Ada
	2005 users.
	(Analyze_Allocator): For an allocator without an initial value, where
	the designated type has a constrained partial view, a discriminant
	constraint is illegal.

From-SVN: r101024

1 files changed, 244 insertions, 32 deletions

diff --git a/gcc/ada/exp_util.adb b/gcc/ada/exp_util.adb
index 4868dc1..eda4383 100644
--- a/gcc/ada/exp_util.adb
+++ b/gcc/ada/exp_util.adb
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---          Copyright (C) 1992-2005, Free Software Foundation, Inc.         --
+--          Copyright (C) 1992-2005 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- --
@@ -47,6 +47,7 @@ with Sem;      use Sem;
 with Sem_Ch8;  use Sem_Ch8;
 with Sem_Eval; use Sem_Eval;
 with Sem_Res;  use Sem_Res;
+with Sem_Type; use Sem_Type;
 with Sem_Util; use Sem_Util;
 with Sinfo;    use Sinfo;
 with Snames;   use Snames;
@@ -107,6 +108,15 @@ package body Exp_Util is
    --  procedure of record with task components, or for a dynamically
    --  created task that is assigned to a selected component.
 
+   procedure Find_Interface_Tag
+     (T         : Entity_Id;
+      Iface     : Entity_Id;
+      Iface_Tag : out Entity_Id;
+      Iface_ADT : out Entity_Id);
+   --  Ada 2005 (AI-251): Subsidiary procedure to Find_Interface_ADT and
+   --  Find_Interface_Tag. Given a type T implementing the interface,
+   --  returns the corresponding Tag and Access_Disp_Table entities.
+
    function Make_CW_Equivalent_Type
      (T : Entity_Id;
       E : Node_Id) return Entity_Id;
@@ -1219,9 +1229,32 @@ package body Exp_Util is
       then
          if Is_Itype (Exp_Typ) then
 
-            --  No need to generate a new one
+            --  Within an initialization procedure, a selected component
+            --  denotes a component of the enclosing record, and it appears
+            --  as an actual in a call to its own initialization procedure.
+            --  If this component depends on the outer discriminant, we must
+            --  generate the proper actual subtype for it.
 
-            T := Exp_Typ;
+            if Nkind (Exp) = N_Selected_Component
+              and then Within_Init_Proc
+            then
+               declare
+                  Decl : constant Node_Id :=
+                           Build_Actual_Subtype_Of_Component (Exp_Typ, Exp);
+               begin
+                  if Present (Decl) then
+                     Insert_Action (N, Decl);
+                     T := Defining_Identifier (Decl);
+                  else
+                     T := Exp_Typ;
+                  end if;
+               end;
+
+            --  No need to generate a new one (new what???)
+
+            else
+               T := Exp_Typ;
+            end if;
 
          else
             T :=
@@ -1261,6 +1294,145 @@ package body Exp_Util is
       end if;
    end Expand_Subtype_From_Expr;
 
+   ------------------------
+   -- Find_Interface_Tag --
+   ------------------------
+
+   procedure Find_Interface_Tag
+     (T         : Entity_Id;
+      Iface     : Entity_Id;
+      Iface_Tag : out Entity_Id;
+      Iface_ADT : out Entity_Id)
+   is
+      AI_Tag   : Entity_Id;
+      ADT_Elmt : Elmt_Id;
+      Found    : Boolean   := False;
+
+      procedure Find_AI_Tag (Typ : in Entity_Id; Found : in out Boolean);
+      --  This must be commented ???
+
+      -----------------
+      -- Find_AI_Tag --
+      -----------------
+
+      procedure Find_AI_Tag (Typ : in Entity_Id; Found : in out Boolean) is
+         T       : Entity_Id := Typ;
+         Etyp    : Entity_Id; -- := Etype (Typ); -- why is this commented ???
+         AI_Elmt : Elmt_Id;
+         AI      : Node_Id;
+
+      begin
+         --  Check if the interface is an immediate ancestor of the type and
+         --  therefore shares the main tag.
+
+         if Typ = Iface then
+            AI_Tag    := First_Tag_Component (Typ);
+            ADT_Elmt  := First_Elmt (Access_Disp_Table (Typ));
+            Found     := True;
+            return;
+         end if;
+
+         --  Handle private types
+
+         if Has_Private_Declaration (T)
+           and then Present (Full_View (T))
+         then
+            T := Full_View (T);
+         end if;
+
+         if Is_Access_Type (Typ) then
+            T := Directly_Designated_Type (T);
+
+         elsif Ekind (T) = E_Protected_Type
+           or else Ekind (T) = E_Task_Type
+         then
+            T := Corresponding_Record_Type (T);
+         end if;
+
+         Etyp := Etype (T);
+
+         --  Climb to the root type
+
+         if Etyp /= Typ then
+            Find_AI_Tag (Etyp, Found);
+         end if;
+
+         --  Traverse the list of interfaces implemented by the type
+
+         if not Found
+           and then Present (Abstract_Interfaces (T))
+           and then not Is_Empty_Elmt_List (Abstract_Interfaces (T))
+         then
+            --  Skip the tag associated with the primary table (if
+            --  already placed in the record)
+
+            if Etype (Node (First_Elmt
+                              (Access_Disp_Table (T)))) = RTE (RE_Tag)
+            then
+               AI_Tag   := Next_Tag_Component (First_Tag_Component (T));
+               ADT_Elmt := Next_Elmt (First_Elmt (Access_Disp_Table (T)));
+            else
+               AI_Tag   := First_Tag_Component (T);
+               ADT_Elmt := First_Elmt (Access_Disp_Table (T));
+            end if;
+
+            pragma Assert (Present (AI_Tag));
+            pragma Assert (Present (Node (ADT_Elmt)));
+
+            AI_Elmt  := First_Elmt (Abstract_Interfaces (T));
+            while Present (AI_Elmt) loop
+               AI := Node (AI_Elmt);
+
+               if AI = Iface or else Is_Ancestor (Iface, AI) then
+                  Found := True;
+                  return;
+               end if;
+
+               AI_Tag := Next_Tag_Component (AI_Tag);
+               Next_Elmt (AI_Elmt);
+               Next_Elmt (ADT_Elmt);
+            end loop;
+         end if;
+      end Find_AI_Tag;
+
+   begin
+      Find_AI_Tag (T, Found);
+      pragma Assert (Found);
+
+      Iface_Tag := AI_Tag;
+      Iface_ADT := Node (ADT_Elmt);
+   end Find_Interface_Tag;
+
+   ------------------------
+   -- Find_Interface_Tag --
+   ------------------------
+
+   function Find_Interface_ADT
+     (T     : Entity_Id;
+      Iface : Entity_Id) return Entity_Id
+   is
+      Iface_Tag : Entity_Id := Empty;
+      Iface_ADT : Entity_Id := Empty;
+   begin
+      Find_Interface_Tag (T, Iface, Iface_Tag, Iface_ADT);
+      return Iface_ADT;
+   end Find_Interface_ADT;
+
+   ------------------------
+   -- Find_Interface_Tag --
+   ------------------------
+
+   function Find_Interface_Tag
+     (T     : Entity_Id;
+      Iface : Entity_Id) return Entity_Id
+   is
+      Iface_Tag : Entity_Id := Empty;
+      Iface_ADT : Entity_Id := Empty;
+   begin
+      Find_Interface_Tag (T, Iface, Iface_Tag, Iface_ADT);
+      return Iface_Tag;
+   end Find_Interface_Tag;
+
    ------------------
    -- Find_Prim_Op --
    ------------------
@@ -1317,10 +1489,9 @@ package body Exp_Util is
       Par              : Node_Id;
 
    begin
-      --  Loop to determine whether there is a component reference in
-      --  the left hand side if Exp appears on the left side of an
-      --  assignment statement. Needed to determine if form of result
-      --  must be a variable.
+      --  Loop to determine whether there is a component reference in the left
+      --  hand side if Exp appears on the left side of an assignment statement.
+      --  Needed to determine if form of result must be a variable.
 
       Par := Exp;
       while Present (Par)
@@ -1339,15 +1510,15 @@ package body Exp_Util is
          end if;
       end loop;
 
-      --  If the expression is a selected component, it is being evaluated
-      --  as part of a discriminant check. If it is part of a left-hand
-      --  side, this is the last use of its value and it is safe to create
-      --  a renaming for it, rather than a temporary. In addition, if it
-      --  is not an addressable field, creating a temporary may be a problem
-      --  for gigi, or might drop the value of the assignment. Therefore,
-      --  if the expression is on the lhs of an assignment, remove side
-      --  effects without requiring a temporary, and create a renaming.
-      --  (See remove_side_effects for details).
+      --  If the expression is a selected component, it is being evaluated as
+      --  part of a discriminant check. If it is part of a left-hand side, this
+      --  is the last use of its value and it is safe to create a renaming for
+      --  it, rather than a temporary. In addition, if it is not an addressable
+      --  field, creating a temporary may be a problem for gigi, or might drop
+      --  the value of the assignment. Therefore, if the expression is on the
+      --  lhs of an assignment, remove side effects without requiring a
+      --  temporary, and create a renaming. (See remove_side_effects for
+      --  details).
 
       Remove_Side_Effects
         (Exp, Name_Req, Variable_Ref => not Component_In_Lhs);
@@ -1423,9 +1594,9 @@ package body Exp_Util is
 
                --  If we fall off the top of the tree, then that's odd, but
                --  perhaps it could occur in some error situation, and the
-               --  safest response is simply to assume that the outcome of
-               --  the condition is unknown. No point in bombing during an
-               --  attempt to optimize things.
+               --  safest response is simply to assume that the outcome of the
+               --  condition is unknown. No point in bombing during an attempt
+               --  to optimize things.
 
                if No (N) then
                   return;
@@ -1448,9 +1619,9 @@ package body Exp_Util is
             end if;
          end;
 
-      --  ELSIF part. Condition is known true within the referenced
-      --  ELSIF, known False in any subsequent ELSIF or ELSE part,
-      --  and unknown before the ELSE part or after the IF statement.
+      --  ELSIF part. Condition is known true within the referenced ELSIF,
+      --  known False in any subsequent ELSIF or ELSE part, and unknown before
+      --  the ELSE part or after the IF statement.
 
       elsif Nkind (CV) = N_Elsif_Part then
          Stm := Parent (CV);
@@ -1468,8 +1639,8 @@ package body Exp_Util is
             return;
          end if;
 
-         --  Again we lack the SLOC of the ELSE, so we need to climb the
-         --  tree to see if we are within the ELSIF part in question.
+         --  Again we lack the SLOC of the ELSE, so we need to climb the tree
+         --  to see if we are within the ELSIF part in question.
 
          declare
             N : Node_Id;
@@ -1481,9 +1652,9 @@ package body Exp_Util is
 
                --  If we fall off the top of the tree, then that's odd, but
                --  perhaps it could occur in some error situation, and the
-               --  safest response is simply to assume that the outcome of
-               --  the condition is unknown. No point in bombing during an
-               --  attempt to optimize things.
+               --  safest response is simply to assume that the outcome of the
+               --  condition is unknown. No point in bombing during an attempt
+               --  to optimize things.
 
                if No (N) then
                   return;
@@ -1510,9 +1681,8 @@ package body Exp_Util is
          return;
       end if;
 
-      --  If we fall through here, then we have a reportable
-      --  condition, Sens is True if the condition is true and
-      --  False if it needs inverting.
+      --  If we fall through here, then we have a reportable condition, Sens is
+      --  True if the condition is true and False if it needs inverting.
 
       --  Deal with NOT operators, inverting sense
 
@@ -2320,6 +2490,47 @@ package body Exp_Util is
       return True;
    end Is_All_Null_Statements;
 
+   ------------------------
+   -- Is_Default_Prim_Op --
+   ------------------------
+
+   function Is_Predefined_Dispatching_Operation
+     (Subp     : Entity_Id) return Boolean
+   is
+      TSS_Name : TSS_Name_Type;
+      E        : Entity_Id := Subp;
+   begin
+      pragma Assert (Is_Dispatching_Operation (Subp));
+
+      --  Handle overriden subprograms
+
+      while Present (Alias (E)) loop
+         E := Alias (E);
+      end loop;
+
+      Get_Name_String (Chars (E));
+
+      if Name_Len > TSS_Name_Type'Last then
+         TSS_Name := TSS_Name_Type (Name_Buffer (Name_Len - TSS_Name'Length + 1
+                                     .. Name_Len));
+         if Chars (E)        = Name_uSize
+           or else Chars (E) = Name_uAlignment
+           or else TSS_Name  = TSS_Stream_Read
+           or else TSS_Name  = TSS_Stream_Write
+           or else TSS_Name  = TSS_Stream_Input
+           or else TSS_Name  = TSS_Stream_Output
+           or else Chars (E) = Name_Op_Eq
+           or else Chars (E) = Name_uAssign
+           or else TSS_Name  = TSS_Deep_Adjust
+           or else TSS_Name  = TSS_Deep_Finalize
+         then
+            return True;
+         end if;
+      end if;
+
+      return False;
+   end Is_Predefined_Dispatching_Operation;
+
    ----------------------------------
    -- Is_Possibly_Unaligned_Object --
    ----------------------------------
@@ -2366,8 +2577,9 @@ package body Exp_Util is
 
          begin
             --  If component reference is for an array with non-static bounds,
-            --  then it is always aligned, we can only unaligned arrays with
-            --  static bounds (more accurately bounds known at compile time)
+            --  then it is always aligned: we can only process unaligned
+            --  arrays with static bounds (more accurately bounds known at
+            --  compile time).
 
             if Is_Array_Type (T)
               and then not Compile_Time_Known_Bounds (T)