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70482933 RK |
1 | ------------------------------------------------------------------------------ |
2 | -- -- | |
3 | -- GNAT COMPILER COMPONENTS -- | |
4 | -- -- | |
5 | -- E X P _ D I S P -- | |
6 | -- -- | |
68ec1a49 | 7 | -- S p e c -- |
70482933 | 8 | -- -- |
1d005acc | 9 | -- Copyright (C) 1992-2019, Free Software Foundation, Inc. -- |
70482933 RK |
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- -- | |
b5c84c3c | 13 | -- ware Foundation; either version 3, or (at your option) any later ver- -- |
70482933 RK |
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 -- | |
b5c84c3c RD |
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. -- | |
70482933 RK |
20 | -- -- |
21 | -- GNAT was originally developed by the GNAT team at New York University. -- | |
71ff80dc | 22 | -- Extensive contributions were provided by Ada Core Technologies Inc. -- |
70482933 RK |
23 | -- -- |
24 | ------------------------------------------------------------------------------ | |
25 | ||
26 | -- This package contains routines involved in tagged types and dynamic | |
758c442c | 27 | -- dispatching expansion. |
70482933 RK |
28 | |
29 | with Types; use Types; | |
024d33d8 | 30 | with Uintp; use Uintp; |
f4d379b8 | 31 | |
70482933 RK |
32 | package Exp_Disp is |
33 | ||
f4d379b8 HK |
34 | ------------------------------------- |
35 | -- Predefined primitive operations -- | |
36 | ------------------------------------- | |
37 | ||
38 | -- The predefined primitive operations (PPOs) are subprograms generated | |
39 | -- by GNAT for a particular tagged type. Their role is to provide support | |
40 | -- for different Ada language features such as the attribute 'Size or | |
41 | -- handling of dispatching triggers in select statements. PPOs are created | |
42 | -- when a tagged type is expanded or frozen. These subprograms are later | |
43 | -- collected and inserted into the dispatch table of a tagged type at | |
44 | -- fixed positions. Some of the PPOs that manipulate data in tagged objects | |
45 | -- require the generation of thunks. | |
46 | ||
47 | -- List of predefined primitive operations | |
48 | ||
49 | -- Leading underscores designate reserved names. Bracketed numerical | |
50 | -- values represent dispatch table slot numbers. | |
51 | ||
52 | -- _Size (1) - implementation of the attribute 'Size for any tagged | |
53 | -- type. Constructs of the form Prefix'Size are converted into | |
54 | -- Prefix._Size. | |
55 | ||
6bed26b5 | 56 | -- TSS_Stream_Read (2) - implementation of the stream attribute Read |
f4d379b8 HK |
57 | -- for any tagged type. |
58 | ||
6bed26b5 | 59 | -- TSS_Stream_Write (3) - implementation of the stream attribute Write |
f4d379b8 HK |
60 | -- for any tagged type. |
61 | ||
6bed26b5 | 62 | -- TSS_Stream_Input (4) - implementation of the stream attribute Input |
f4d379b8 HK |
63 | -- for any tagged type. |
64 | ||
6bed26b5 | 65 | -- TSS_Stream_Output (5) - implementation of the stream attribute |
f4d379b8 HK |
66 | -- Output for any tagged type. |
67 | ||
6bed26b5 | 68 | -- Op_Eq (6) - implementation of the equality operator for any non- |
f4d379b8 HK |
69 | -- limited tagged type. |
70 | ||
6bed26b5 | 71 | -- _Assign (7) - implementation of the assignment operator for any |
f4d379b8 HK |
72 | -- non-limited tagged type. |
73 | ||
6bed26b5 | 74 | -- TSS_Deep_Adjust (8) - implementation of the finalization operation |
f4d379b8 HK |
75 | -- Adjust for any non-limited tagged type. |
76 | ||
6bed26b5 | 77 | -- TSS_Deep_Finalize (9) - implementation of the finalization |
f4d379b8 HK |
78 | -- operation Finalize for any non-limited tagged type. |
79 | ||
6bed26b5 | 80 | -- _Disp_Asynchronous_Select (10) - used in the expansion of ATC with |
f4d379b8 HK |
81 | -- dispatching triggers. Null implementation for limited interfaces, |
82 | -- full body generation for types that implement limited interfaces, | |
83 | -- not generated for the rest of the cases. See Expand_N_Asynchronous_ | |
84 | -- Select in Exp_Ch9 for more information. | |
85 | ||
6bed26b5 | 86 | -- _Disp_Conditional_Select (11) - used in the expansion of conditional |
f4d379b8 HK |
87 | -- selects with dispatching triggers. Null implementation for limited |
88 | -- interfaces, full body generation for types that implement limited | |
89 | -- interfaces, not generated for the rest of the cases. See Expand_N_ | |
90 | -- Conditional_Entry_Call in Exp_Ch9 for more information. | |
91 | ||
6bed26b5 | 92 | -- _Disp_Get_Prim_Op_Kind (12) - helper routine used in the expansion |
f4d379b8 HK |
93 | -- of ATC with dispatching triggers. Null implementation for limited |
94 | -- interfaces, full body generation for types that implement limited | |
95 | -- interfaces, not generated for the rest of the cases. | |
96 | ||
6bed26b5 | 97 | -- _Disp_Get_Task_Id (13) - helper routine used in the expansion of |
f4d379b8 HK |
98 | -- Abort, attributes 'Callable and 'Terminated for task interface |
99 | -- class-wide types. Full body generation for task types, null | |
100 | -- implementation for limited interfaces, not generated for the rest | |
101 | -- of the cases. See Expand_N_Attribute_Reference in Exp_Attr and | |
102 | -- Expand_N_Abort_Statement in Exp_Ch9 for more information. | |
103 | ||
6bed26b5 | 104 | -- _Disp_Requeue (14) - used in the expansion of dispatching requeue |
80b992ae HK |
105 | -- statements. Null implementation is provided for protected, task |
106 | -- and synchronized interfaces. Protected and task types implementing | |
107 | -- concurrent interfaces receive full bodies. See Expand_N_Requeue_ | |
108 | -- Statement in Exp_Ch9 for more information. | |
109 | ||
6bed26b5 | 110 | -- _Disp_Timed_Select (15) - used in the expansion of timed selects |
f4d379b8 HK |
111 | -- with dispatching triggers. Null implementation for limited |
112 | -- interfaces, full body generation for types that implement limited | |
113 | -- interfaces, not generated for the rest of the cases. See Expand_N_ | |
114 | -- Timed_Entry_Call for more information. | |
115 | ||
d0dd5209 | 116 | -- Life cycle of predefined primitive operations |
f4d379b8 HK |
117 | |
118 | -- The specifications and bodies of the PPOs are created by | |
119 | -- Make_Predefined_Primitive_Specs and Predefined_Primitive_Bodies | |
120 | -- in Exp_Ch3. The generated specifications are immediately analyzed, | |
121 | -- while the bodies are left as freeze actions to the tagged type for | |
122 | -- which they are created. | |
123 | ||
124 | -- PPOs are collected and added to the Primitive_Operations list of | |
125 | -- a type by the regular analysis mechanism. | |
126 | ||
b2e1beb3 | 127 | -- PPOs are frozen by Exp_Ch3.Predefined_Primitive_Freeze |
f4d379b8 | 128 | |
b2e1beb3 | 129 | -- Thunks for PPOs are created by Make_DT |
f4d379b8 | 130 | |
b2e1beb3 | 131 | -- Dispatch table positions of PPOs are set by Set_All_DT_Position |
f4d379b8 | 132 | |
d0dd5209 JM |
133 | -- Calls to PPOs proceed as regular dispatching calls. If the PPO |
134 | -- has a thunk, a call proceeds as a regular dispatching call with | |
f4d379b8 HK |
135 | -- a thunk. |
136 | ||
137 | -- Guidelines for addition of new predefined primitive operations | |
138 | ||
b2e1beb3 ES |
139 | -- Update the value of constant Max_Predef_Prims in a-tags.ads to |
140 | -- indicate the new number of PPOs. | |
f4d379b8 HK |
141 | |
142 | -- Introduce a new predefined name for the new PPO in Snames.ads and | |
143 | -- Snames.adb. | |
144 | ||
145 | -- Categorize the new PPO name as predefined by adding an entry in | |
5afaf827 | 146 | -- Is_Predefined_Dispatching_Operation in Exp_Disp. |
f4d379b8 | 147 | |
f4d379b8 HK |
148 | -- Generate the specification of the new PPO in Make_Predefined_ |
149 | -- Primitive_Spec in Exp_Ch3.adb. The Is_Internal flag of the defining | |
150 | -- identifier of the specification must be set to True. | |
151 | ||
152 | -- Generate the body of the new PPO in Predefined_Primitive_Bodies in | |
153 | -- Exp_Ch3.adb. The Is_Internal flag of the defining identifier of the | |
154 | -- specification must be set to True. | |
155 | ||
156 | -- If the new PPO requires a thunk, add an entry in Freeze_Subprogram | |
157 | -- in Exp_Ch6.adb. | |
158 | ||
159 | -- When generating calls to a PPO, use Find_Prim_Op from Exp_Util.ads | |
160 | -- to retrieve the entity of the operation directly. | |
161 | ||
10b93b2e HK |
162 | -- Number of predefined primitive operations added by the Expander |
163 | -- for a tagged type. If more predefined primitive operations are | |
164 | -- added, the following items must be changed: | |
165 | ||
b2e1beb3 | 166 | -- Ada.Tags.Max_Predef_Prims - indirect use |
10b93b2e HK |
167 | -- Exp_Disp.Default_Prim_Op_Position - indirect use |
168 | -- Exp_Disp.Set_All_DT_Position - direct use | |
169 | ||
5a1ccfb1 AC |
170 | procedure Apply_Tag_Checks (Call_Node : Node_Id); |
171 | -- Generate checks required on dispatching calls | |
172 | ||
6e818918 JM |
173 | function Building_Static_DT (Typ : Entity_Id) return Boolean; |
174 | pragma Inline (Building_Static_DT); | |
175 | -- Returns true when building statically allocated dispatch tables | |
176 | ||
15529d0a PMR |
177 | function Building_Static_Secondary_DT (Typ : Entity_Id) return Boolean; |
178 | pragma Inline (Building_Static_Secondary_DT); | |
179 | -- Returns true when building statically allocated secondary dispatch | |
180 | -- tables | |
181 | ||
b2e1beb3 ES |
182 | procedure Build_Static_Dispatch_Tables (N : Node_Id); |
183 | -- N is a library level package declaration or package body. Build the | |
184 | -- static dispatch table of the tagged types defined at library level. In | |
185 | -- case of package declarations with private part the generated nodes are | |
186 | -- added at the end of the list of private declarations. Otherwise they are | |
187 | -- added to the end of the list of public declarations. In case of package | |
188 | -- bodies they are added to the end of the list of declarations of the | |
189 | -- package body. | |
190 | ||
bed8af19 AC |
191 | function Convert_Tag_To_Interface |
192 | (Typ : Entity_Id; Expr : Node_Id) return Node_Id; | |
193 | pragma Inline (Convert_Tag_To_Interface); | |
194 | -- This function is used in class-wide interface conversions; the expanded | |
195 | -- code generated to convert a tagged object to a class-wide interface type | |
196 | -- involves referencing the tag component containing the secondary dispatch | |
197 | -- table associated with the interface. Given the expression Expr that | |
198 | -- references a tag component, we cannot generate an unchecked conversion | |
199 | -- to leave the expression decorated with the class-wide interface type Typ | |
200 | -- because an unchecked conversion cannot be seen as a no-op. An unchecked | |
201 | -- conversion is conceptually a function call and therefore the RM allows | |
202 | -- the backend to obtain a copy of the value of the actual object and store | |
203 | -- it in some other place (like a register); in such case the interface | |
204 | -- conversion is not equivalent to a displacement of the pointer to the | |
205 | -- interface and any further displacement fails. Although the functionality | |
206 | -- of this function is simple and could be done directly, the purpose of | |
207 | -- this routine is to leave well documented in the sources these | |
208 | -- occurrences. | |
209 | ||
210 | -- If Expr is an N_Selected_Component that references a tag generate: | |
211 | -- type ityp is non null access Typ; | |
212 | -- ityp!(Expr'Address).all | |
213 | ||
214 | -- if Expr is an N_Function_Call to Ada.Tags.Displace then generate: | |
215 | -- type ityp is non null access Typ; | |
216 | -- ityp!(Expr).all | |
217 | ||
cefce34c JM |
218 | function CPP_Num_Prims (Typ : Entity_Id) return Nat; |
219 | -- Return the number of primitives of the C++ part of the dispatch table. | |
220 | -- For types that are not derivations of CPP types return 0. | |
221 | ||
fe683ef6 AC |
222 | function Elab_Flag_Needed (Typ : Entity_Id) return Boolean; |
223 | -- Return True if the elaboration of the tagged type Typ is completed at | |
83b77c5c | 224 | -- run time by the execution of code located in the IP routine and the |
fe683ef6 AC |
225 | -- expander must generate an extra elaboration flag to avoid performing |
226 | -- such elaboration twice. | |
227 | ||
10b93b2e HK |
228 | procedure Expand_Dispatching_Call (Call_Node : Node_Id); |
229 | -- Expand the call to the operation through the dispatch table and perform | |
dee4682a JM |
230 | -- the required tag checks when appropriate. For CPP types tag checks are |
231 | -- not relevant. | |
10b93b2e | 232 | |
524c02d7 | 233 | procedure Expand_Interface_Actuals (Call_Node : Node_Id); |
10b93b2e HK |
234 | -- Ada 2005 (AI-251): Displace all the actuals corresponding to class-wide |
235 | -- interfaces to reference the interface tag of the actual object | |
236 | ||
f6f4d8d4 JM |
237 | procedure Expand_Interface_Conversion (N : Node_Id); |
238 | -- Ada 2005 (AI-251): N is a type-conversion node. Displace the pointer | |
239 | -- to the object to give access to the interface tag associated with the | |
240 | -- dispatch table of the target type. | |
10b93b2e | 241 | |
d0dd5209 | 242 | procedure Expand_Interface_Thunk |
b2e1beb3 ES |
243 | (Prim : Node_Id; |
244 | Thunk_Id : out Entity_Id; | |
20dc266e JM |
245 | Thunk_Code : out Node_Id; |
246 | Iface : Entity_Id); | |
10b93b2e | 247 | -- Ada 2005 (AI-251): When a tagged type implements abstract interfaces we |
b2e1beb3 ES |
248 | -- generate additional subprograms (thunks) associated with each primitive |
249 | -- Prim to have a layout compatible with the C++ ABI. The thunk displaces | |
250 | -- the pointers to the actuals that depend on the controlling type before | |
251 | -- transferring control to the target subprogram. If there is no need to | |
252 | -- generate the thunk then Thunk_Id and Thunk_Code are set to Empty. | |
253 | -- Otherwise they are set to the defining identifier and the subprogram | |
254 | -- body of the generated thunk. | |
255 | ||
cefce34c JM |
256 | function Has_CPP_Constructors (Typ : Entity_Id) return Boolean; |
257 | -- Returns true if the type has CPP constructors | |
258 | ||
7af1cf83 AC |
259 | function Is_Expanded_Dispatching_Call (N : Node_Id) return Boolean; |
260 | -- Returns true if N is the expanded code of a dispatching call | |
261 | ||
b2e1beb3 ES |
262 | function Make_DT (Typ : Entity_Id; N : Node_Id := Empty) return List_Id; |
263 | -- Expand the declarations for the Dispatch Table. The node N is the | |
264 | -- declaration that forces the generation of the table. It is used to place | |
265 | -- error messages when the declaration leads to the freezing of a given | |
266 | -- primitive operation that has an incomplete non- tagged formal. | |
70482933 | 267 | |
10b93b2e HK |
268 | function Make_Disp_Asynchronous_Select_Body |
269 | (Typ : Entity_Id) return Node_Id; | |
270 | -- Ada 2005 (AI-345): Generate the body of the primitive operation of type | |
f4d379b8 HK |
271 | -- Typ used for dispatching in asynchronous selects. Generate a null body |
272 | -- if Typ is an interface type. | |
10b93b2e HK |
273 | |
274 | function Make_Disp_Asynchronous_Select_Spec | |
275 | (Typ : Entity_Id) return Node_Id; | |
276 | -- Ada 2005 (AI-345): Generate the specification of the primitive operation | |
277 | -- of type Typ used for dispatching in asynchronous selects. | |
278 | ||
279 | function Make_Disp_Conditional_Select_Body | |
280 | (Typ : Entity_Id) return Node_Id; | |
281 | -- Ada 2005 (AI-345): Generate the body of the primitive operation of type | |
f4d379b8 HK |
282 | -- Typ used for dispatching in conditional selects. Generate a null body |
283 | -- if Typ is an interface type. | |
10b93b2e HK |
284 | |
285 | function Make_Disp_Conditional_Select_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 dispatching in conditional selects. | |
289 | ||
290 | function Make_Disp_Get_Prim_Op_Kind_Body | |
291 | (Typ : Entity_Id) return Node_Id; | |
292 | -- Ada 2005 (AI-345): Generate the body of the primitive operation of type | |
293 | -- Typ used for retrieving the callable entity kind during dispatching in | |
f4d379b8 | 294 | -- asynchronous selects. Generate a null body if Typ is an interface type. |
10b93b2e HK |
295 | |
296 | function Make_Disp_Get_Prim_Op_Kind_Spec | |
297 | (Typ : Entity_Id) return Node_Id; | |
298 | -- Ada 2005 (AI-345): Generate the specification of the primitive operation | |
299 | -- of the type Typ use for retrieving the callable entity kind during | |
300 | -- dispatching in asynchronous selects. | |
301 | ||
f4d379b8 HK |
302 | function Make_Disp_Get_Task_Id_Body |
303 | (Typ : Entity_Id) return Node_Id; | |
b2e1beb3 ES |
304 | -- Ada 2005 (AI-345): Generate body of the primitive operation of type Typ |
305 | -- used for retrieving the _task_id field of a task interface class- wide | |
306 | -- type. Generate a null body if Typ is an interface or a non-task type. | |
f4d379b8 HK |
307 | |
308 | function Make_Disp_Get_Task_Id_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 retrieving the _task_id field of a task interface | |
312 | -- class-wide type. | |
10b93b2e | 313 | |
80b992ae HK |
314 | function Make_Disp_Requeue_Body |
315 | (Typ : Entity_Id) return Node_Id; | |
316 | -- Ada 2005 (AI05-0030): Generate the body of the primitive operation of | |
317 | -- type Typ used for dispatching on requeue statements. Generate a body | |
318 | -- containing a single null-statement if Typ is an interface type. | |
319 | ||
320 | function Make_Disp_Requeue_Spec | |
321 | (Typ : Entity_Id) return Node_Id; | |
322 | -- Ada 2005 (AI05-0030): Generate the specification of the primitive | |
323 | -- operation of type Typ used for dispatching requeue statements. | |
324 | ||
10b93b2e HK |
325 | function Make_Disp_Timed_Select_Body |
326 | (Typ : Entity_Id) return Node_Id; | |
327 | -- Ada 2005 (AI-345): Generate the body of the primitive operation of type | |
80b992ae | 328 | -- Typ used for dispatching in timed selects. Generate a body containing |
d0dd5209 | 329 | -- a single null-statement if Typ is an interface type. |
10b93b2e HK |
330 | |
331 | function Make_Disp_Timed_Select_Spec | |
332 | (Typ : Entity_Id) return Node_Id; | |
333 | -- Ada 2005 (AI-345): Generate the specification of the primitive operation | |
334 | -- of type Typ used for dispatching in timed selects. | |
335 | ||
f4d379b8 HK |
336 | function Make_Select_Specific_Data_Table |
337 | (Typ : Entity_Id) return List_Id; | |
338 | -- Ada 2005 (AI-345): Create and populate the auxiliary table in the TSD | |
339 | -- of Typ used for dispatching in asynchronous, conditional and timed | |
340 | -- selects. Generate code to set the primitive operation kinds and entry | |
3b42c566 | 341 | -- indexes of primitive operations and primitive wrappers. |
f4d379b8 | 342 | |
b2e1beb3 ES |
343 | function Make_Tags (Typ : Entity_Id) return List_Id; |
344 | -- Generate the entities associated with the primary and secondary tags of | |
345 | -- Typ and fill the contents of Access_Disp_Table. In case of library level | |
346 | -- tagged types this routine imports the forward declaration of the tag | |
347 | -- entity, that will be declared and exported by Make_DT. | |
348 | ||
991395ab | 349 | function Register_Primitive |
d0dd5209 | 350 | (Loc : Source_Ptr; |
991395ab AC |
351 | Prim : Entity_Id) return List_Id; |
352 | -- Build code to register Prim in the primary or secondary dispatch table. | |
d0dd5209 JM |
353 | -- If Prim is associated with a secondary dispatch table then generate also |
354 | -- its thunk and register it in the associated secondary dispatch table. | |
355 | -- In general the dispatch tables are always generated by Make_DT and | |
356 | -- Make_Secondary_DT; this routine is only used in two corner cases: | |
991395ab | 357 | -- |
d0dd5209 JM |
358 | -- 1) To construct the dispatch table of a tagged type whose parent |
359 | -- is a CPP_Class (see Build_Init_Procedure). | |
360 | -- 2) To handle late overriding of dispatching operations (see | |
991395ab AC |
361 | -- Check_Dispatching_Operation and Make_DT). |
362 | -- | |
363 | -- The caller is responsible for inserting the generated code in the | |
364 | -- proper place. | |
f4d379b8 | 365 | |
70482933 RK |
366 | procedure Set_All_DT_Position (Typ : Entity_Id); |
367 | -- Set the DT_Position field for each primitive operation. In the CPP | |
758c442c | 368 | -- Class case check that no pragma CPP_Virtual is missing and that the |
70482933 RK |
369 | -- DT_Position are coherent |
370 | ||
236fecbf JM |
371 | procedure Set_CPP_Constructors (Typ : Entity_Id); |
372 | -- Typ is a CPP_Class type. Create the Init procedures of that type | |
373 | -- required to handle its default and non-default constructors. The | |
374 | -- functions to which pragma CPP_Constructor is applied in the sources | |
375 | -- are functions returning this type, and having an implicit access to the | |
376 | -- target object in its first argument; such implicit argument is explicit | |
377 | -- in the IP procedures built here. | |
70482933 | 378 | |
024d33d8 JM |
379 | procedure Set_DT_Position_Value (Prim : Entity_Id; Value : Uint); |
380 | -- Set the position of a dispatching primitive its dispatch table. For | |
381 | -- subprogram wrappers propagate the value to the wrapped subprogram. | |
382 | ||
383 | procedure Set_DTC_Entity_Value (Tagged_Type : Entity_Id; Prim : Entity_Id); | |
d0dd5209 | 384 | -- Set the definite value of the DTC_Entity value associated with a given |
3830827c | 385 | -- primitive of a tagged type. For subprogram wrappers, propagate the value |
024d33d8 | 386 | -- to the wrapped subprogram. |
d0dd5209 | 387 | |
758c442c GD |
388 | procedure Write_DT (Typ : Entity_Id); |
389 | pragma Export (Ada, Write_DT); | |
390 | -- Debugging procedure (to be called within gdb) | |
391 | ||
70482933 | 392 | end Exp_Disp; |