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1 | ------------------------------------------------------------------------------ |
2 | -- -- | |
3 | -- GNAT COMPILER COMPONENTS -- | |
4 | -- -- | |
5 | -- S E M _ C H 1 3 -- | |
6 | -- -- | |
7 | -- S p e c -- | |
996ae0b0 | 8 | -- -- |
3ddfabe3 | 9 | -- Copyright (C) 1992-2016, Free Software Foundation, Inc. -- |
996ae0b0 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- -- |
996ae0b0 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. -- | |
996ae0b0 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. -- |
996ae0b0 RK |
23 | -- -- |
24 | ------------------------------------------------------------------------------ | |
25 | ||
105b5e65 | 26 | with Table; |
996ae0b0 RK |
27 | with Types; use Types; |
28 | with Uintp; use Uintp; | |
29 | ||
30 | package Sem_Ch13 is | |
31 | procedure Analyze_At_Clause (N : Node_Id); | |
32 | procedure Analyze_Attribute_Definition_Clause (N : Node_Id); | |
33 | procedure Analyze_Enumeration_Representation_Clause (N : Node_Id); | |
34 | procedure Analyze_Free_Statement (N : Node_Id); | |
3ff38f33 | 35 | procedure Analyze_Freeze_Entity (N : Node_Id); |
3cd4a210 | 36 | procedure Analyze_Freeze_Generic_Entity (N : Node_Id); |
996ae0b0 RK |
37 | procedure Analyze_Record_Representation_Clause (N : Node_Id); |
38 | procedure Analyze_Code_Statement (N : Node_Id); | |
39 | ||
eaba57fb RD |
40 | procedure Analyze_Aspect_Specifications (N : Node_Id; E : Entity_Id); |
41 | -- This procedure is called to analyze aspect specifications for node N. E | |
42 | -- is the corresponding entity declared by the declaration node N. Callers | |
43 | -- should check that Has_Aspects (N) is True before calling this routine. | |
0f1a6a0b | 44 | |
caf07df9 AC |
45 | procedure Analyze_Aspect_Specifications_On_Body_Or_Stub (N : Node_Id); |
46 | -- Analyze the aspect specifications of [generic] subprogram body or stub | |
47 | -- N. Callers should check that Has_Aspects (N) is True before calling the | |
48 | -- routine. This routine diagnoses misplaced aspects that should appear on | |
49 | -- the initial declaration of N and offers suggestions for replacements. | |
50 | ||
a9a5b8ac RD |
51 | procedure Adjust_Record_For_Reverse_Bit_Order (R : Entity_Id); |
52 | -- Called from Freeze where R is a record entity for which reverse bit | |
53 | -- order is specified and there is at least one component clause. Adjusts | |
8a95f4e8 RD |
54 | -- component positions according to either Ada 95 or Ada 2005 (AI-133). |
55 | ||
56 | procedure Check_Record_Representation_Clause (N : Node_Id); | |
57 | -- This procedure completes the analysis of a record representation clause | |
58 | -- N. It is called at freeze time after adjustment of component clause bit | |
59 | -- positions for possible non-standard bit order. In the case of Ada 2005 | |
60 | -- (machine scalar) mode, this adjustment can make substantial changes, so | |
61 | -- some checks, in particular for component overlaps cannot be done at the | |
62 | -- time the record representation clause is first seen, but must be delayed | |
63 | -- till freeze time, and in particular is called after calling the above | |
64 | -- procedure for adjusting record bit positions for reverse bit order. | |
a9a5b8ac | 65 | |
996ae0b0 RK |
66 | procedure Initialize; |
67 | -- Initialize internal tables for new compilation | |
68 | ||
cf28c974 RD |
69 | procedure Kill_Rep_Clause (N : Node_Id); |
70 | -- This procedure is called for a rep clause N when we are in -gnatI mode | |
39678b1c | 71 | -- (Ignore_Rep_Clauses). It replaces the node N with a null statement. This |
cf28c974 RD |
72 | -- is only called if Ignore_Rep_Clauses is True. |
73 | ||
996ae0b0 RK |
74 | procedure Set_Enum_Esize (T : Entity_Id); |
75 | -- This routine sets the Esize field for an enumeration type T, based | |
76 | -- on the current representation information available for T. Note that | |
77 | -- the setting of the RM_Size field is not affected. This routine also | |
78 | -- initializes the alignment field to zero. | |
79 | ||
80 | function Minimum_Size | |
81 | (T : Entity_Id; | |
0da2c8ac | 82 | Biased : Boolean := False) return Nat; |
15ce9ca2 | 83 | -- Given an elementary type, determines the minimum number of bits required |
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84 | -- to represent all values of the type. This function may not be called |
85 | -- with any other types. If the flag Biased is set True, then the minimum | |
86 | -- size calculation that biased representation is used in the case of a | |
87 | -- discrete type, e.g. the range 7..8 gives a minimum size of 4 with | |
88 | -- Biased set to False, and 1 with Biased set to True. Note that the | |
89 | -- biased parameter only has an effect if the type is not biased, it | |
90 | -- causes Minimum_Size to indicate the minimum size of an object with | |
91 | -- the given type, of the size the type would have if it were biased. If | |
92 | -- the type is already biased, then Minimum_Size returns the biased size, | |
93 | -- regardless of the setting of Biased. Also, fixed-point types are never | |
4b92fd3c ST |
94 | -- biased in the current implementation. If the size is not known at |
95 | -- compile time, this function returns 0. | |
996ae0b0 | 96 | |
fbf5a39b AC |
97 | procedure Check_Constant_Address_Clause (Expr : Node_Id; U_Ent : Entity_Id); |
98 | -- Expr is an expression for an address clause. This procedure checks | |
99 | -- that the expression is constant, in the limited sense that it is safe | |
100 | -- to evaluate it at the point the object U_Ent is declared, rather than | |
101 | -- at the point of the address clause. The condition for this to be true | |
102 | -- is that the expression has no variables, no constants declared after | |
103 | -- U_Ent, and no calls to non-pure functions. If this condition is not | |
104 | -- met, then an appropriate error message is posted. This check is applied | |
105 | -- at the point an object with an address clause is frozen, as well as for | |
106 | -- address clauses for tasks and entries. | |
107 | ||
996ae0b0 RK |
108 | procedure Check_Size |
109 | (N : Node_Id; | |
110 | T : Entity_Id; | |
111 | Siz : Uint; | |
112 | Biased : out Boolean); | |
113 | -- Called when size Siz is specified for subtype T. This subprogram checks | |
114 | -- that the size is appropriate, posting errors on node N as required. | |
81a5b587 AC |
115 | -- This check is effective for elementary types and bit-packed arrays. |
116 | -- For other non-elementary types, a check is only made if an explicit | |
117 | -- size has been given for the type (and the specified size must match). | |
118 | -- The parameter Biased is set False if the size specified did not require | |
996ae0b0 RK |
119 | -- the use of biased representation, and True if biased representation |
120 | -- was required to meet the size requirement. Note that Biased is only | |
121 | -- set if the type is not currently biased, but biasing it is the only | |
122 | -- way to meet the requirement. If the type is currently biased, then | |
123 | -- this biased size is used in the initial check, and Biased is False. | |
81a5b587 AC |
124 | -- If the size is too small, and an error message is given, then both |
125 | -- Esize and RM_Size are reset to the allowed minimum value in T. | |
996ae0b0 | 126 | |
0da2c8ac | 127 | function Rep_Item_Too_Early (T : Entity_Id; N : Node_Id) return Boolean; |
82d4f390 RD |
128 | -- Called at start of processing a representation clause/pragma. Used to |
129 | -- check that the representation item is not being applied to an incomplete | |
130 | -- type or to a generic formal type or a type derived from a generic formal | |
131 | -- type. Returns False if no such error occurs. If this error does occur, | |
132 | -- appropriate error messages are posted on node N, and True is returned. | |
996ae0b0 | 133 | |
e477d718 AC |
134 | generic |
135 | with procedure Replace_Type_Reference (N : Node_Id); | |
136 | procedure Replace_Type_References_Generic (N : Node_Id; T : Entity_Id); | |
137 | -- This is used to scan an expression for a predicate or invariant aspect | |
138 | -- replacing occurrences of the name of the subtype to which the aspect | |
139 | -- applies with appropriate references to the parameter of the predicate | |
140 | -- function or invariant procedure. The procedure passed as a generic | |
141 | -- parameter does the actual replacement of node N, which is either a | |
142 | -- simple direct reference to T, or a selected component that represents | |
143 | -- an appropriately qualified occurrence of T. | |
144 | ||
996ae0b0 RK |
145 | function Rep_Item_Too_Late |
146 | (T : Entity_Id; | |
147 | N : Node_Id; | |
0da2c8ac | 148 | FOnly : Boolean := False) return Boolean; |
996ae0b0 | 149 | -- Called at the start of processing a representation clause or a |
82d4f390 RD |
150 | -- representation pragma. Used to check that a representation item for |
151 | -- entity T does not appear too late (according to the rules in RM 13.1(9) | |
152 | -- and RM 13.1(10)). N is the associated node, which in the pragma case | |
153 | -- is the pragma or representation clause itself, used for placing error | |
154 | -- messages if the item is too late. | |
996ae0b0 RK |
155 | -- |
156 | -- Fonly is a flag that causes only the freezing rule (para 9) to be | |
82d4f390 RD |
157 | -- applied, and the tests of para 10 are skipped. This is appropriate for |
158 | -- both subtype related attributes (Alignment and Size) and for stream | |
159 | -- attributes, which, although certainly not subtype related attributes, | |
160 | -- clearly should not be subject to the para 10 restrictions (see | |
161 | -- AI95-00137). Similarly, we also skip the para 10 restrictions for | |
868e30a5 | 162 | -- the Storage_Size case where they also clearly do not apply, and for |
f3d0f304 | 163 | -- Stream_Convert which is in the same category as the stream attributes. |
996ae0b0 | 164 | -- |
82d4f390 RD |
165 | -- If the rep item is too late, an appropriate message is output and True |
166 | -- is returned, which is a signal that the caller should abandon processing | |
167 | -- for the item. If the item is not too late, then False is returned, and | |
168 | -- the caller can continue processing the item. | |
996ae0b0 RK |
169 | -- |
170 | -- If no error is detected, this call also as a side effect links the | |
171 | -- representation item onto the head of the representation item chain | |
172 | -- (referenced by the First_Rep_Item field of the entity). | |
173 | -- | |
82d4f390 RD |
174 | -- Note: Rep_Item_Too_Late must be called with the underlying type in the |
175 | -- case of a private or incomplete type. The protocol is to first check for | |
176 | -- Rep_Item_Too_Early using the initial entity, then take the underlying | |
177 | -- type, then call Rep_Item_Too_Late on the result. | |
c159409f AC |
178 | -- |
179 | -- Note: Calls to Rep_Item_Too_Late are ignored for the case of attribute | |
180 | -- definition clauses which have From_Aspect_Specification set. This is | |
181 | -- because such clauses are linked on to the Rep_Item chain in procedure | |
182 | -- Sem_Ch13.Analyze_Aspect_Specifications. See that procedure for details. | |
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183 | |
184 | function Same_Representation (Typ1, Typ2 : Entity_Id) return Boolean; | |
185 | -- Given two types, where the two types are related by possible derivation, | |
186 | -- determines if the two types have the same representation, or different | |
187 | -- representations, requiring the special processing for representation | |
188 | -- change. A False result is possible only for array, enumeration or | |
189 | -- record types. | |
190 | ||
191 | procedure Validate_Unchecked_Conversion | |
192 | (N : Node_Id; | |
193 | Act_Unit : Entity_Id); | |
194 | -- Validate a call to unchecked conversion. N is the node for the actual | |
195 | -- instantiation, which is used only for error messages. Act_Unit is the | |
f3d57416 | 196 | -- entity for the instantiation, from which the actual types etc. for this |
996ae0b0 RK |
197 | -- instantiation can be determined. This procedure makes an entry in a |
198 | -- table and/or generates an N_Validate_Unchecked_Conversion node. The | |
199 | -- actual checking is done in Validate_Unchecked_Conversions or in the | |
200 | -- back end as required. | |
201 | ||
202 | procedure Validate_Unchecked_Conversions; | |
105b5e65 AC |
203 | -- This routine is called after calling the backend to validate unchecked |
204 | -- conversions for size and alignment appropriateness. The reason it is | |
205 | -- called that late is to take advantage of any back-annotation of size | |
206 | -- and alignment performed by the backend. | |
996ae0b0 | 207 | |
2642f998 RD |
208 | procedure Validate_Address_Clauses; |
209 | -- This is called after the back end has been called (and thus after the | |
210 | -- alignments of objects have been back annotated). It goes through the | |
211 | -- table of saved address clauses checking for suspicious alignments and | |
212 | -- if necessary issuing warnings. | |
213 | ||
105b5e65 AC |
214 | procedure Validate_Independence; |
215 | -- This is called after the back end has been called (and thus after the | |
216 | -- layout of components has been back annotated). It goes through the | |
217 | -- table of saved pragma Independent[_Component] entries, checking that | |
308e6f3a | 218 | -- independence can be achieved, and if necessary issuing error messages. |
105b5e65 AC |
219 | |
220 | ------------------------------------- | |
221 | -- Table for Validate_Independence -- | |
222 | ------------------------------------- | |
223 | ||
224 | -- If a legal pragma Independent or Independent_Components is given for | |
225 | -- an entity, then an entry is made in this table, to be checked by a | |
226 | -- call to Validate_Independence after back annotation of layout is done. | |
227 | ||
228 | type Independence_Check_Record is record | |
229 | N : Node_Id; | |
230 | -- The pragma Independent or Independent_Components | |
231 | ||
232 | E : Entity_Id; | |
233 | -- The entity to which it applies | |
234 | end record; | |
235 | ||
236 | package Independence_Checks is new Table.Table ( | |
237 | Table_Component_Type => Independence_Check_Record, | |
238 | Table_Index_Type => Int, | |
239 | Table_Low_Bound => 1, | |
240 | Table_Initial => 20, | |
241 | Table_Increment => 200, | |
242 | Table_Name => "Independence_Checks"); | |
243 | ||
47e11d08 AC |
244 | ----------------------------------- |
245 | -- Handling of Aspect Visibility -- | |
246 | ----------------------------------- | |
247 | ||
248 | -- The visibility of aspects is tricky. First, the visibility is delayed | |
249 | -- to the freeze point. This is not too complicated, what we do is simply | |
250 | -- to leave the aspect "laying in wait" for the freeze point, and at that | |
b98e2969 | 251 | -- point materialize and analyze the corresponding attribute definition |
47e11d08 AC |
252 | -- clause or pragma. There is some special processing for preconditions |
253 | -- and postonditions, where the pragmas themselves deal with the required | |
254 | -- delay, but basically the approach is the same, delay analysis of the | |
255 | -- expression to the freeze point. | |
256 | ||
257 | -- Much harder is the requirement for diagnosing cases in which an early | |
258 | -- freeze causes a change in visibility. Consider: | |
259 | ||
260 | -- package AspectVis is | |
261 | -- R_Size : constant Integer := 32; | |
262 | -- | |
263 | -- package Inner is | |
264 | -- type R is new Integer with | |
265 | -- Size => R_Size; | |
266 | -- F : R; -- freezes | |
267 | -- R_Size : constant Integer := 64; | |
268 | -- S : constant Integer := R'Size; -- 32 not 64 | |
269 | -- end Inner; | |
270 | -- end AspectVis; | |
271 | ||
272 | -- Here the 32 not 64 shows what would be expected if this program were | |
273 | -- legal, since the evaluation of R_Size has to be done at the freeze | |
274 | -- point and gets the outer definition not the inner one. | |
275 | ||
276 | -- But the language rule requires this program to be diagnosed as illegal | |
277 | -- because the visibility changes between the freeze point and the end of | |
278 | -- the declarative region. | |
279 | ||
280 | -- To meet this requirement, we first note that the Expression field of the | |
281 | -- N_Aspect_Specification node holds the raw unanalyzed expression, which | |
282 | -- will get used in processing the aspect. At the time of analyzing the | |
283 | -- N_Aspect_Specification node, we create a complete copy of the expression | |
284 | -- and store it in the entity field of the Identifier (an odd usage, but | |
285 | -- the identifier is not used except to identify the aspect, so its Entity | |
286 | -- field is otherwise unused, and we are short of room in the node). | |
287 | ||
288 | -- This copy stays unanalyzed up to the freeze point, where we analyze the | |
289 | -- resulting pragma or attribute definition clause, except that in the | |
290 | -- case of invariants and predicates, we mark occurrences of the subtype | |
291 | -- name as having the entity of the subprogram parameter, so that they | |
292 | -- will not cause trouble in the following steps. | |
293 | ||
294 | -- Then at the freeze point, we create another copy of this unanalyzed | |
295 | -- expression. By this time we no longer need the Expression field for | |
296 | -- other purposes, so we can store it there. Now we have two copies of | |
297 | -- the original unanalyzed expression. One of them gets preanalyzed at | |
298 | -- the freeze point to capture the visibility at the freeze point. | |
299 | ||
300 | -- Now when we hit the freeze all at the end of the declarative part, if | |
301 | -- we come across a frozen entity with delayed aspects, we still have one | |
302 | -- copy of the unanalyzed expression available in the node, and we again | |
303 | -- do a preanalysis using that copy and the visibility at the end of the | |
304 | -- declarative part. Now we have two preanalyzed expression (preanalysis | |
305 | -- is good enough, since we are only interested in referenced entities). | |
306 | -- One captures the visibility at the freeze point, the other captures the | |
307 | -- visibility at the end of the declarative part. We see if the entities | |
308 | -- in these two expressions are the same, by seeing if the two expressions | |
309 | -- are fully conformant, and if not, issue appropriate error messages. | |
310 | ||
a90bd866 | 311 | -- Quite an awkward approach, but this is an awkard requirement |
47e11d08 | 312 | |
8a0320ad | 313 | procedure Analyze_Aspects_At_Freeze_Point (E : Entity_Id); |
15e934bf AC |
314 | -- Analyze all the delayed aspects for entity E at freezing point. This |
315 | -- includes dealing with inheriting delayed aspects from the parent type | |
316 | -- in the case where a derived type is frozen. | |
8a0320ad | 317 | |
47e11d08 AC |
318 | procedure Check_Aspect_At_Freeze_Point (ASN : Node_Id); |
319 | -- Performs the processing described above at the freeze point, ASN is the | |
320 | -- N_Aspect_Specification node for the aspect. | |
321 | ||
322 | procedure Check_Aspect_At_End_Of_Declarations (ASN : Node_Id); | |
323 | -- Performs the processing described above at the freeze all point, and | |
324 | -- issues appropriate error messages if the visibility has indeed changed. | |
325 | -- Again, ASN is the N_Aspect_Specification node for the aspect. | |
dc3af7e2 AC |
326 | |
327 | procedure Inherit_Aspects_At_Freeze_Point (Typ : Entity_Id); | |
328 | -- Given an entity Typ that denotes a derived type or a subtype, this | |
329 | -- routine performs the inheritance of aspects at the freeze point. | |
dd2bf554 | 330 | |
f06f5f6b AC |
331 | procedure Resolve_Aspect_Expressions (E : Entity_Id); |
332 | -- Name resolution of an aspect expression happens at the end of the | |
333 | -- current declarative part or at the freeze point for the entity, | |
334 | -- whichever comes first. For declarations in the visible part of a | |
335 | -- package, name resolution takes place before analysis of the private | |
336 | -- part even though the freeze point of the entity may appear later. | |
337 | ||
dd2bf554 ES |
338 | procedure Validate_Iterable_Aspect (Typ : Entity_Id; ASN : Node_Id); |
339 | -- For SPARK 2014 formal containers. The expression has the form of an | |
82d4f390 RD |
340 | -- aggregate, and each entry must denote a function with the proper syntax |
341 | -- for First, Next, and Has_Element. Optionally an Element primitive may | |
342 | -- also be defined. | |
343 | ||
77a40ec1 AC |
344 | ----------------------------------------------------------- |
345 | -- Visibility of Discriminants in Aspect Specifications -- | |
346 | ----------------------------------------------------------- | |
347 | ||
348 | -- The discriminants of a type are visible when analyzing the aspect | |
349 | -- specifications of a type declaration or protected type declaration, | |
350 | -- but not when analyzing those of a subtype declaration. The following | |
351 | -- routines enforce this distinction. | |
352 | ||
353 | procedure Install_Discriminants (E : Entity_Id); | |
354 | -- Make visible the discriminants of type entity E | |
355 | ||
356 | procedure Push_Scope_And_Install_Discriminants (E : Entity_Id); | |
357 | -- Push scope E and makes visible the discriminants of type entity E if E | |
358 | -- has discriminants and is not a subtype. | |
359 | ||
360 | procedure Uninstall_Discriminants (E : Entity_Id); | |
361 | -- Remove visibility to the discriminants of type entity E | |
362 | ||
363 | procedure Uninstall_Discriminants_And_Pop_Scope (E : Entity_Id); | |
364 | -- Remove visibility to the discriminants of type entity E and pop the | |
365 | -- scope stack if E has discriminants and is not a subtype. | |
366 | ||
996ae0b0 | 367 | end Sem_Ch13; |