1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
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. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 -- This package contains routines involved in tagged types and dynamic
27 -- dispatching expansion.
29 with Types; use Types;
33 -------------------------------
34 -- SCIL Node Type Definition --
35 -------------------------------
37 type Scil_Node_Kind is (
41 Dispatch_Table_Object_Init,
42 Dispatch_Table_Tag_Init);
44 -------------------------------------
45 -- Predefined primitive operations --
46 -------------------------------------
48 -- The predefined primitive operations (PPOs) are subprograms generated
49 -- by GNAT for a particular tagged type. Their role is to provide support
50 -- for different Ada language features such as the attribute 'Size or
51 -- handling of dispatching triggers in select statements. PPOs are created
52 -- when a tagged type is expanded or frozen. These subprograms are later
53 -- collected and inserted into the dispatch table of a tagged type at
54 -- fixed positions. Some of the PPOs that manipulate data in tagged objects
55 -- require the generation of thunks.
57 -- List of predefined primitive operations
59 -- Leading underscores designate reserved names. Bracketed numerical
60 -- values represent dispatch table slot numbers.
62 -- _Size (1) - implementation of the attribute 'Size for any tagged
63 -- type. Constructs of the form Prefix'Size are converted into
66 -- _Alignment (2) - implementation of the attribute 'Alignment for
67 -- any tagged type. Constructs of the form Prefix'Alignment are
68 -- converted into Prefix._Alignment.
70 -- TSS_Stream_Read (3) - implementation of the stream attribute Read
71 -- for any tagged type.
73 -- TSS_Stream_Write (4) - implementation of the stream attribute Write
74 -- for any tagged type.
76 -- TSS_Stream_Input (5) - implementation of the stream attribute Input
77 -- for any tagged type.
79 -- TSS_Stream_Output (6) - implementation of the stream attribute
80 -- Output for any tagged type.
82 -- Op_Eq (7) - implementation of the equality operator for any non-
83 -- limited tagged type.
85 -- _Assign (8) - implementation of the assignment operator for any
86 -- non-limited tagged type.
88 -- TSS_Deep_Adjust (9) - implementation of the finalization operation
89 -- Adjust for any non-limited tagged type.
91 -- TSS_Deep_Finalize (10) - implementation of the finalization
92 -- operation Finalize for any non-limited tagged type.
94 -- _Disp_Asynchronous_Select (11) - used in the expansion of ATC with
95 -- dispatching triggers. Null implementation for limited interfaces,
96 -- full body generation for types that implement limited interfaces,
97 -- not generated for the rest of the cases. See Expand_N_Asynchronous_
98 -- Select in Exp_Ch9 for more information.
100 -- _Disp_Conditional_Select (12) - used in the expansion of conditional
101 -- selects with dispatching triggers. Null implementation for limited
102 -- interfaces, full body generation for types that implement limited
103 -- interfaces, not generated for the rest of the cases. See Expand_N_
104 -- Conditional_Entry_Call in Exp_Ch9 for more information.
106 -- _Disp_Get_Prim_Op_Kind (13) - helper routine used in the expansion
107 -- of ATC with dispatching triggers. Null implementation for limited
108 -- interfaces, full body generation for types that implement limited
109 -- interfaces, not generated for the rest of the cases.
111 -- _Disp_Get_Task_Id (14) - helper routine used in the expansion of
112 -- Abort, attributes 'Callable and 'Terminated for task interface
113 -- class-wide types. Full body generation for task types, null
114 -- implementation for limited interfaces, not generated for the rest
115 -- of the cases. See Expand_N_Attribute_Reference in Exp_Attr and
116 -- Expand_N_Abort_Statement in Exp_Ch9 for more information.
118 -- _Disp_Requeue (15) - used in the expansion of dispatching requeue
119 -- statements. Null implementation is provided for protected, task
120 -- and synchronized interfaces. Protected and task types implementing
121 -- concurrent interfaces receive full bodies. See Expand_N_Requeue_
122 -- Statement in Exp_Ch9 for more information.
124 -- _Disp_Timed_Select (16) - used in the expansion of timed selects
125 -- with dispatching triggers. Null implementation for limited
126 -- interfaces, full body generation for types that implement limited
127 -- interfaces, not generated for the rest of the cases. See Expand_N_
128 -- Timed_Entry_Call for more information.
130 -- Life cycle of predefined primitive operations
132 -- The specifications and bodies of the PPOs are created by
133 -- Make_Predefined_Primitive_Specs and Predefined_Primitive_Bodies
134 -- in Exp_Ch3. The generated specifications are immediately analyzed,
135 -- while the bodies are left as freeze actions to the tagged type for
136 -- which they are created.
138 -- PPOs are collected and added to the Primitive_Operations list of
139 -- a type by the regular analysis mechanism.
141 -- PPOs are frozen by Exp_Ch3.Predefined_Primitive_Freeze
143 -- Thunks for PPOs are created by Make_DT
145 -- Dispatch table positions of PPOs are set by Set_All_DT_Position
147 -- Calls to PPOs proceed as regular dispatching calls. If the PPO
148 -- has a thunk, a call proceeds as a regular dispatching call with
151 -- Guidelines for addition of new predefined primitive operations
153 -- Update the value of constant Max_Predef_Prims in a-tags.ads to
154 -- indicate the new number of PPOs.
156 -- Introduce a new predefined name for the new PPO in Snames.ads and
159 -- Categorize the new PPO name as predefined by adding an entry in
160 -- Is_Predefined_Dispatching_Operation in Exp_Disp.
162 -- Generate the specification of the new PPO in Make_Predefined_
163 -- Primitive_Spec in Exp_Ch3.adb. The Is_Internal flag of the defining
164 -- identifier of the specification must be set to True.
166 -- Generate the body of the new PPO in Predefined_Primitive_Bodies in
167 -- Exp_Ch3.adb. The Is_Internal flag of the defining identifier of the
168 -- specification must be set to True.
170 -- If the new PPO requires a thunk, add an entry in Freeze_Subprogram
173 -- When generating calls to a PPO, use Find_Prim_Op from Exp_Util.ads
174 -- to retrieve the entity of the operation directly.
176 -- Number of predefined primitive operations added by the Expander
177 -- for a tagged type. If more predefined primitive operations are
178 -- added, the following items must be changed:
180 -- Ada.Tags.Max_Predef_Prims - indirect use
181 -- Exp_Disp.Default_Prim_Op_Position - indirect use
182 -- Exp_Disp.Set_All_DT_Position - direct use
184 procedure Apply_Tag_Checks (Call_Node : Node_Id);
185 -- Generate checks required on dispatching calls
187 function Building_Static_DT (Typ : Entity_Id) return Boolean;
188 pragma Inline (Building_Static_DT);
189 -- Returns true when building statically allocated dispatch tables
191 procedure Build_Static_Dispatch_Tables (N : Node_Id);
192 -- N is a library level package declaration or package body. Build the
193 -- static dispatch table of the tagged types defined at library level. In
194 -- case of package declarations with private part the generated nodes are
195 -- added at the end of the list of private declarations. Otherwise they are
196 -- added to the end of the list of public declarations. In case of package
197 -- bodies they are added to the end of the list of declarations of the
200 procedure Expand_Dispatching_Call (Call_Node : Node_Id);
201 -- Expand the call to the operation through the dispatch table and perform
202 -- the required tag checks when appropriate. For CPP types tag checks are
205 procedure Expand_Interface_Actuals (Call_Node : Node_Id);
206 -- Ada 2005 (AI-251): Displace all the actuals corresponding to class-wide
207 -- interfaces to reference the interface tag of the actual object
209 procedure Expand_Interface_Conversion
211 Is_Static : Boolean := True);
212 -- Ada 2005 (AI-251): N is a type-conversion node. Reference the base of
213 -- the object to give access to the interface tag associated with the
214 -- secondary dispatch table.
216 procedure Expand_Interface_Thunk
218 Thunk_Id : out Entity_Id;
219 Thunk_Code : out Node_Id);
220 -- Ada 2005 (AI-251): When a tagged type implements abstract interfaces we
221 -- generate additional subprograms (thunks) associated with each primitive
222 -- Prim to have a layout compatible with the C++ ABI. The thunk displaces
223 -- the pointers to the actuals that depend on the controlling type before
224 -- transferring control to the target subprogram. If there is no need to
225 -- generate the thunk then Thunk_Id and Thunk_Code are set to Empty.
226 -- Otherwise they are set to the defining identifier and the subprogram
227 -- body of the generated thunk.
229 function Get_Scil_Node_Kind (Node : Node_Id) return Scil_Node_Kind;
230 -- Returns the kind of an SCIL node
232 function Is_Predefined_Dispatching_Operation (E : Entity_Id) return Boolean;
233 -- Ada 2005 (AI-251): Determines if E is a predefined primitive operation
235 function Is_Predefined_Interface_Primitive (E : Entity_Id) return Boolean;
236 -- Ada 2005 (AI-345): Returns True if E is one of the predefined primitives
237 -- required to implement interfaces.
239 function Make_DT (Typ : Entity_Id; N : Node_Id := Empty) return List_Id;
240 -- Expand the declarations for the Dispatch Table. The node N is the
241 -- declaration that forces the generation of the table. It is used to place
242 -- error messages when the declaration leads to the freezing of a given
243 -- primitive operation that has an incomplete non- tagged formal.
245 function Make_Disp_Asynchronous_Select_Body
246 (Typ : Entity_Id) return Node_Id;
247 -- Ada 2005 (AI-345): Generate the body of the primitive operation of type
248 -- Typ used for dispatching in asynchronous selects. Generate a null body
249 -- if Typ is an interface type.
251 function Make_Disp_Asynchronous_Select_Spec
252 (Typ : Entity_Id) return Node_Id;
253 -- Ada 2005 (AI-345): Generate the specification of the primitive operation
254 -- of type Typ used for dispatching in asynchronous selects.
256 function Make_Disp_Conditional_Select_Body
257 (Typ : Entity_Id) return Node_Id;
258 -- Ada 2005 (AI-345): Generate the body of the primitive operation of type
259 -- Typ used for dispatching in conditional selects. Generate a null body
260 -- if Typ is an interface type.
262 function Make_Disp_Conditional_Select_Spec
263 (Typ : Entity_Id) return Node_Id;
264 -- Ada 2005 (AI-345): Generate the specification of the primitive operation
265 -- of type Typ used for dispatching in conditional selects.
267 function Make_Disp_Get_Prim_Op_Kind_Body
268 (Typ : Entity_Id) return Node_Id;
269 -- Ada 2005 (AI-345): Generate the body of the primitive operation of type
270 -- Typ used for retrieving the callable entity kind during dispatching in
271 -- asynchronous selects. Generate a null body if Typ is an interface type.
273 function Make_Disp_Get_Prim_Op_Kind_Spec
274 (Typ : Entity_Id) return Node_Id;
275 -- Ada 2005 (AI-345): Generate the specification of the primitive operation
276 -- of the type Typ use for retrieving the callable entity kind during
277 -- dispatching in asynchronous selects.
279 function Make_Disp_Get_Task_Id_Body
280 (Typ : Entity_Id) return Node_Id;
281 -- Ada 2005 (AI-345): Generate body of the primitive operation of type Typ
282 -- used for retrieving the _task_id field of a task interface class- wide
283 -- type. Generate a null body if Typ is an interface or a non-task type.
285 function Make_Disp_Get_Task_Id_Spec
286 (Typ : Entity_Id) return Node_Id;
287 -- Ada 2005 (AI-345): Generate the specification of the primitive operation
288 -- of type Typ used for retrieving the _task_id field of a task interface
291 function Make_Disp_Requeue_Body
292 (Typ : Entity_Id) return Node_Id;
293 -- Ada 2005 (AI05-0030): Generate the body of the primitive operation of
294 -- type Typ used for dispatching on requeue statements. Generate a body
295 -- containing a single null-statement if Typ is an interface type.
297 function Make_Disp_Requeue_Spec
298 (Typ : Entity_Id) return Node_Id;
299 -- Ada 2005 (AI05-0030): Generate the specification of the primitive
300 -- operation of type Typ used for dispatching requeue statements.
302 function Make_Disp_Timed_Select_Body
303 (Typ : Entity_Id) return Node_Id;
304 -- Ada 2005 (AI-345): Generate the body of the primitive operation of type
305 -- Typ used for dispatching in timed selects. Generate a body containing
306 -- a single null-statement if Typ is an interface type.
308 function Make_Disp_Timed_Select_Spec
309 (Typ : Entity_Id) return Node_Id;
310 -- Ada 2005 (AI-345): Generate the specification of the primitive operation
311 -- of type Typ used for dispatching in timed selects.
313 function Make_Select_Specific_Data_Table
314 (Typ : Entity_Id) return List_Id;
315 -- Ada 2005 (AI-345): Create and populate the auxiliary table in the TSD
316 -- of Typ used for dispatching in asynchronous, conditional and timed
317 -- selects. Generate code to set the primitive operation kinds and entry
318 -- indices of primitive operations and primitive wrappers.
320 function Make_Tags (Typ : Entity_Id) return List_Id;
321 -- Generate the entities associated with the primary and secondary tags of
322 -- Typ and fill the contents of Access_Disp_Table. In case of library level
323 -- tagged types this routine imports the forward declaration of the tag
324 -- entity, that will be declared and exported by Make_DT.
326 function New_Scil_Node
327 (Nkind : Scil_Node_Kind;
328 Related_Node : Node_Id;
329 Entity : Entity_Id := Empty;
330 Target_Prim : Entity_Id := Empty) return Node_Id;
331 -- Creates a new Scil node. Related_Node is the AST node associated with
332 -- this Scil node. Entity is the tagged type associated with the Scil node.
333 -- For Dispatching_Call nodes, Target_Prim is the dispatching primitive.
335 function Register_Primitive
337 Prim : Entity_Id) return List_Id;
338 -- Build code to register Prim in the primary or secondary dispatch table.
339 -- If Prim is associated with a secondary dispatch table then generate also
340 -- its thunk and register it in the associated secondary dispatch table.
341 -- In general the dispatch tables are always generated by Make_DT and
342 -- Make_Secondary_DT; this routine is only used in two corner cases:
344 -- 1) To construct the dispatch table of a tagged type whose parent
345 -- is a CPP_Class (see Build_Init_Procedure).
346 -- 2) To handle late overriding of dispatching operations (see
347 -- Check_Dispatching_Operation and Make_DT).
349 -- The caller is responsible for inserting the generated code in the
352 procedure Set_All_DT_Position (Typ : Entity_Id);
353 -- Set the DT_Position field for each primitive operation. In the CPP
354 -- Class case check that no pragma CPP_Virtual is missing and that the
355 -- DT_Position are coherent
357 procedure Set_CPP_Constructors (Typ : Entity_Id);
358 -- Typ is a CPP_Class type. Create the Init procedures of that type
359 -- required to handle its default and non-default constructors. The
360 -- functions to which pragma CPP_Constructor is applied in the sources
361 -- are functions returning this type, and having an implicit access to the
362 -- target object in its first argument; such implicit argument is explicit
363 -- in the IP procedures built here.
365 procedure Set_DTC_Entity_Value
366 (Tagged_Type : Entity_Id;
368 -- Set the definite value of the DTC_Entity value associated with a given
369 -- primitive of a tagged type.
371 procedure Write_DT (Typ : Entity_Id);
372 pragma Export (Ada, Write_DT);
373 -- Debugging procedure (to be called within gdb)