1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                             E X P _ A T A G                              --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 2006-2011, Free Software Foundation, Inc.         --
10--                                                                          --
11-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
17-- for  more details.  You should have  received  a copy of the GNU General --
18-- Public License  distributed with GNAT; see file COPYING3.  If not, go to --
19-- http://www.gnu.org/licenses for a complete copy of the license.          --
20--                                                                          --
21-- GNAT was originally developed  by the GNAT team at  New York University. --
22-- Extensive contributions were provided by Ada Core Technologies Inc.      --
23--                                                                          --
24------------------------------------------------------------------------------
25
26--  This package contains routines involved in the frontend expansion of
27--  subprograms of package Ada.Tags
28
29with Types; use Types;
30with Uintp; use Uintp;
31
32package Exp_Atag is
33
34   --  Note: In all the subprograms of this package formal 'Loc' is the source
35   --  location used in constructing the corresponding nodes.
36
37   procedure Build_Common_Dispatching_Select_Statements
38     (Typ   : Entity_Id;
39      Stmts : List_Id);
40   --  Ada 2005 (AI-345): Build statements that are common to the expansion of
41   --  timed, asynchronous, and conditional select and append them to Stmts.
42   --  Typ is the tagged type used for dispatching calls.
43
44   procedure Build_CW_Membership
45     (Loc          : Source_Ptr;
46      Obj_Tag_Node : in out Node_Id;
47      Typ_Tag_Node : Node_Id;
48      Related_Nod  : Node_Id;
49      New_Node     : out Node_Id);
50   --  Build code that returns true if Obj_Tag is in Typ_Tag'Class. Each DT
51   --  has a table of ancestors and its inheritance level (Idepth). Obj is in
52   --  Typ'Class if Typ'Tag is found in the table of ancestors referenced by
53   --  Obj'Tag. Knowing the level of inheritance of both types, this can be
54   --  computed in constant time by the formula:
55   --
56   --   Index := TSD (Obj'Tag).Idepth - TSD (Typ'Tag).Idepth;
57   --   Index > 0 and then TSD (Obj'Tag).Tags_Table (Index) = Typ'Tag
58   --
59   --  Related_Nod is the node where the implicit declaration of variable Index
60   --  is inserted. Obj_Tag_Node is relocated.
61
62   function Build_Get_Access_Level
63     (Loc      : Source_Ptr;
64      Tag_Node : Node_Id) return Node_Id;
65   --  Build code that retrieves the accessibility level of the tagged type.
66   --
67   --  Generates: TSD (Tag).Access_Level
68
69   function Build_Get_Alignment
70     (Loc      : Source_Ptr;
71      Tag_Node : Node_Id) return Node_Id;
72   --  Build code that retrieves the alignment of the tagged type.
73   --  Generates: TSD (Tag).Alignment
74
75   procedure Build_Get_Predefined_Prim_Op_Address
76     (Loc      : Source_Ptr;
77      Position : Uint;
78      Tag_Node : in out Node_Id;
79      New_Node : out Node_Id);
80   --  Given a pointer to a dispatch table (T) and a position in the DT, build
81   --  code that gets the address of the predefined virtual function stored in
82   --  it (used for dispatching calls). Tag_Node is relocated.
83   --
84   --  Generates: Predefined_DT (Tag).D (Position);
85
86   procedure Build_Get_Prim_Op_Address
87     (Loc      : Source_Ptr;
88      Typ      : Entity_Id;
89      Position : Uint;
90      Tag_Node : in out Node_Id;
91      New_Node : out Node_Id);
92   --  Build code that retrieves the address of the virtual function stored in
93   --  a given position of the dispatch table (used for dispatching calls).
94   --  Tag_Node is relocated.
95   --
96   --  Generates: To_Tag (Tag).D (Position);
97
98   function Build_Get_Transportable
99     (Loc      : Source_Ptr;
100      Tag_Node : Node_Id) return Node_Id;
101   --  Build code that retrieves the value of the Transportable flag for
102   --  the given Tag.
103   --
104   --  Generates: TSD (Tag).Transportable;
105
106   function Build_Inherit_CPP_Prims (Typ : Entity_Id) return List_Id;
107   --  Build code that copies from Typ's parent the dispatch table slots of
108   --  inherited primitives and updates slots of overridden primitives. The
109   --  generated code handles primary and secondary dispatch tables of Typ.
110
111   function Build_Inherit_Predefined_Prims
112     (Loc          : Source_Ptr;
113      Old_Tag_Node : Node_Id;
114      New_Tag_Node : Node_Id) return Node_Id;
115   --  Build code that inherits the predefined primitives of the parent.
116   --
117   --  Generates: Predefined_DT (New_T).D (All_Predefined_Prims) :=
118   --               Predefined_DT (Old_T).D (All_Predefined_Prims);
119   --
120   --  Required to build non-library level dispatch tables. Also required
121   --  when compiling without static dispatch tables support.
122
123   function Build_Inherit_Prims
124     (Loc          : Source_Ptr;
125      Typ          : Entity_Id;
126      Old_Tag_Node : Node_Id;
127      New_Tag_Node : Node_Id;
128      Num_Prims    : Nat) return Node_Id;
129   --  Build code that inherits Num_Prims user-defined primitives from the
130   --  dispatch table of the parent type of tagged type Typ. It is used to
131   --  copy the dispatch table of the parent in the following cases:
132   --    a) case of derivations of CPP_Class types
133   --    b) tagged types whose dispatch table is not statically allocated
134   --
135   --  Generates:
136   --    New_Tag.Prims_Ptr (1 .. Num_Prims) :=
137   --      Old_Tag.Prims_Ptr (1 .. Num_Prims);
138
139   function Build_Offset_To_Top
140     (Loc       : Source_Ptr;
141      This_Node : Node_Id) return Node_Id;
142   --  Build code that references the Offset_To_Top component of the primary
143   --  or secondary dispatch table associated with This_Node. This subprogram
144   --  provides a subset of the functionality provided by the function
145   --  Offset_To_Top of package Ada.Tags, and is only called by the frontend
146   --  when such routine is not available in a configurable runtime.
147   --
148   --  Generates:
149   --    Offset_To_Top_Ptr
150   --      (Address!(Tag_Ptr!(This).all) - Offset_To_Top_Offset)
151
152   function Build_Set_Predefined_Prim_Op_Address
153     (Loc          : Source_Ptr;
154      Tag_Node     : Node_Id;
155      Position     : Uint;
156      Address_Node : Node_Id) return Node_Id;
157   --  Build code that saves the address of a virtual function in a given
158   --  Position of the portion of the dispatch table associated with the
159   --  predefined primitives of Tag. Called from Exp_Disp.Fill_DT_Entry
160   --  and Exp_Disp.Fill_Secondary_DT_Entry. It is used for:
161   --   1) Filling the dispatch table of CPP_Class types.
162   --   2) Late overriding (see Check_Dispatching_Operation).
163   --
164   --  Generates: Predefined_DT (Tag).D (Position) := Value
165
166   function Build_Set_Prim_Op_Address
167     (Loc          : Source_Ptr;
168      Typ          : Entity_Id;
169      Tag_Node     : Node_Id;
170      Position     : Uint;
171      Address_Node : Node_Id) return Node_Id;
172   --  Build code that saves the address of a virtual function in a given
173   --  Position of the dispatch table associated with the Tag. Called from
174   --  Exp_Disp.Fill_DT_Entry and Exp_Disp.Fill_Secondary_DT_Entry. Used for:
175   --   1) Filling the dispatch table of CPP_Class types.
176   --   2) Late overriding (see Check_Dispatching_Operation).
177   --
178   --  Generates: Tag.D (Position) := Value
179
180   function Build_Set_Size_Function
181     (Loc       : Source_Ptr;
182      Tag_Node  : Node_Id;
183      Size_Func : Entity_Id) return Node_Id;
184   --  Build code that saves in the TSD the address of the function
185   --  calculating _size of the object.
186
187   function Build_Set_Static_Offset_To_Top
188     (Loc          : Source_Ptr;
189      Iface_Tag    : Node_Id;
190      Offset_Value : Node_Id) return Node_Id;
191   --  Build code that initialize the Offset_To_Top component of the
192   --  secondary dispatch table referenced by Iface_Tag.
193   --
194   --  Generates:
195   --    Offset_To_Top_Ptr
196   --      (Address!(Tag_Ptr!(This).all) - Offset_To_Top_Offset).all
197   --     := Offset_Value
198
199end Exp_Atag;
200