| blob | 09363af823e61ae38171d294b3b3ec08bf4362b5 |
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- F R E E Z E --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2006, 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 2, 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 COPYING. If not, write --
19 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
21 -- --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 -- --
25 ------------------------------------------------------------------------------
65 -----------------------
66 -- Local Subprograms --
67 -----------------------
70 -- Typ is a type that is being frozen. If no size clause is given,
71 -- but a default Esize has been computed, then this default Esize is
72 -- adjusted up if necessary to be consistent with a given alignment,
73 -- but never to a value greater than Long_Long_Integer'Size. This
74 -- is used for all discrete types and for fixed-point types.
76 procedure Build_And_Analyze_Renamed_Body
80 -- Build body for a renaming declaration, insert in tree and analyze
83 -- Apply legality checks to address clauses for object declarations,
84 -- at the point the object is frozen.
87 -- E is a base type. If E is tagged or has a component that is aliased
88 -- or tagged or contains something this is aliased or tagged, set
89 -- Strict_Alignment.
93 -- If E is a fixed-point or discrete type, then all the necessary work
94 -- to freeze it is completed except for possible setting of the flag
95 -- Is_Unsigned_Type, which is done by this procedure. The call has no
96 -- effect if the entity E is not a discrete or fixed-point type.
98 procedure Freeze_And_Append
102 -- Freezes Ent using Freeze_Entity, and appends the resulting list of
103 -- nodes to Result, modifying Result from No_List if necessary.
106 -- Freeze enumeration type. The Esize field is set as processing
107 -- proceeds (i.e. set by default when the type is declared and then
108 -- adjusted by rep clauses. What this procedure does is to make sure
109 -- that if a foreign convention is specified, and no specific size
110 -- is given, then the size must be at least Integer'Size.
113 -- If an object is frozen which has Is_Statically_Allocated set, then
114 -- all referenced types must also be marked with this flag. This routine
115 -- is in charge of meeting this requirement for the object entity E.
118 -- Perform freezing actions for a subprogram (create extra formals,
119 -- and set proper default mechanism values). Note that this routine
120 -- is not called for internal subprograms, for which neither of these
121 -- actions is needed (or desirable, we do not want for example to have
122 -- these extra formals present in initialization procedures, where they
123 -- would serve no purpose). In this call E is either a subprogram or
124 -- a subprogram type (i.e. an access to a subprogram).
127 -- True if T is not private and has no private components, or has a full
128 -- view. Used to determine whether the designated type of an access type
129 -- should be frozen when the access type is frozen. This is done when an
130 -- allocator is frozen, or an expression that may involve attributes of
131 -- the designated type. Otherwise freezing the access type does not freeze
132 -- the designated type.
134 procedure Process_Default_Expressions
137 -- This procedure is called for each subprogram to complete processing
138 -- of default expressions at the point where all types are known to be
139 -- frozen. The expressions must be analyzed in full, to make sure that
140 -- all error processing is done (they have only been pre-analyzed). If
141 -- the expression is not an entity or literal, its analysis may generate
142 -- code which must not be executed. In that case we build a function
143 -- body to hold that code. This wrapper function serves no other purpose
144 -- (it used to be called to evaluate the default, but now the default is
145 -- inlined at each point of call).
148 -- Typ is a record or array type that is being frozen. This routine
149 -- sets the default component alignment from the scope stack values
150 -- if the alignment is otherwise not specified.
153 -- As each entity is frozen, this routine is called to deal with the
154 -- setting of Debug_Info_Needed for the entity. This flag is set if
155 -- the entity comes from source, or if we are in Debug_Generated_Code
156 -- mode or if the -gnatdV debug flag is set. However, it never sets
157 -- the flag if Debug_Info_Off is set.
160 -- Sets the Debug_Info_Needed flag on entity T if not already set, and
161 -- also on any entities that are needed by T (for an object, the type
162 -- of the object is needed, and for a type, the subsidiary types are
163 -- needed -- see body for details). Never has any effect on T if the
164 -- Debug_Info_Off flag is set.
167 -- T is a type of a component that we know to be an Itype.
168 -- We don't want this to have a Freeze_Node, so ensure it doesn't.
169 -- Do the same for any Full_View or Corresponding_Record_Type.
171 procedure Warn_Overlay
175 -- Expr is the expression for an address clause for entity Nam whose type
176 -- is Typ. If Typ has a default initialization, and there is no explicit
177 -- initialization in the source declaration, check whether the address
178 -- clause might cause overlaying of an entity, and emit a warning on the
179 -- side effect that the initialization will cause.
181 -------------------------------
182 -- Adjust_Esize_For_Alignment --
183 -------------------------------
188 begin
194 then
200 ------------------------------------
201 -- Build_And_Analyze_Renamed_Body --
202 ------------------------------------
204 procedure Build_And_Analyze_Renamed_Body
208 is
210 begin
217 ------------------------
218 -- Build_Renamed_Body --
219 ------------------------
221 function Build_Renamed_Body
224 is
226 -- We use for the source location of the renamed body, the location
227 -- of the spec entity. It might seem more natural to use the location
228 -- of the renaming declaration itself, but that would be wrong, since
229 -- then the body we create would look as though it was created far
230 -- too late, and this could cause problems with elaboration order
231 -- analysis, particularly in connection with instantiations.
245 begin
246 -- Determine the entity being renamed, which is the target of the
247 -- call statement. If the name is an explicit dereference, this is
248 -- a renaming of a subprogram type rather than a subprogram. The
249 -- name itself is fully analyzed.
260 else
267 else
273 -- If the renamed entity is a predefined operator, retain full
274 -- name to ensure its visibility.
278 then
280 else
284 else
287 -- The original name may have been overloaded, but
288 -- is fully resolved now.
293 -- For simple renamings, subsequent calls can be expanded directly
294 -- as called to the renamed entity. The body must be generated in
295 -- any case for calls they may appear elsewhere.
300 then
304 -- The body generated for this renaming is an internal artifact, and
305 -- does not constitute a freeze point for the called entity.
320 -- If the renamed entity is an entry, inherit its profile. For
321 -- other renamings as bodies, both profiles must be subtype
322 -- conformant, so it is not necessary to replace the profile given
323 -- in the declaration. However, default values that are aggregates
324 -- are rewritten when partially analyzed, so we recover the original
325 -- aggregate to insure that subsequent conformity checking works.
326 -- Similarly, if the default expression was constant-folded, recover
327 -- the original expression.
339 N_Access_Definition
340 then
348 then
359 -- If the renamed entity is a function, the generated body contains a
360 -- return statement. Otherwise, build a procedure call. If the entity is
361 -- an entry, subsequent analysis of the call will transform it into the
362 -- proper entry or protected operation call. If the renamed entity is
363 -- a character literal, return it directly.
369 then
370 Call_Node :=
372 Expression =>
378 Call_Node :=
383 Call_Node :=
387 else
388 Call_Node :=
394 -- Create entities for subprogram body and formals
408 Body_Node :=
412 Handled_Statement_Sequence =>
422 -- Link the body to the entity whose declaration it completes. If
423 -- the body is analyzed when the renamed entity is frozen, it may be
424 -- necessary to restore the proper scope (see package Exp_Ch13).
428 then
430 else
437 --------------------------
438 -- Check_Address_Clause --
439 --------------------------
447 begin
451 -- If we have no initialization of any kind, then we don't
452 -- need to place any restrictions on the address clause, because
453 -- the object will be elaborated after the address clause is
454 -- evaluated. This happens if the declaration has no initial
455 -- expression, or the type has no implicit initialization, or
456 -- the object is imported.
458 -- The same holds for all initialized scalar types and all
459 -- access types. Packed bit arrays of size up to 64 are
460 -- represented using a modular type with an initialization
461 -- (to zero) and can be processed like other initialized
462 -- scalar types.
464 -- If the type is controlled, code to attach the object to a
465 -- finalization chain is generated at the point of declaration,
466 -- and therefore the elaboration of the object cannot be delayed:
467 -- the address expression must be a constant.
471 and then
475 or else
479 or else
482 or else
484 and then
486 then
489 -- Otherwise, we require the address clause to be constant
490 -- because the call to the initialization procedure (or the
491 -- attach code) has to happen at the point of the declaration.
493 else
500 then
506 -----------------------------
507 -- Check_Compile_Time_Size --
508 -----------------------------
513 -- Sets the compile time known size (32 bits or less) in the Esize
514 -- field, of T checking for a size clause that was given which attempts
515 -- to give a smaller size.
518 -- Recursive function that does all the work
521 -- If T is a constrained subtype, its size is not known if any of its
522 -- discriminant constraints is not static and it is not a null record.
523 -- The test is conservative and doesn't check that the components are
524 -- in fact constrained by non-static discriminant values. Could be made
525 -- more precise ???
527 --------------------
528 -- Set_Small_Size --
529 --------------------
532 begin
539 Error_Msg_NE
547 -- Set sizes if not set already
549 else
560 ----------------
561 -- Size_Known --
562 ----------------
571 begin
577 then
589 -- Don't do any recursion on type with error posted, since
590 -- we may have a malformed type that leads us into a loop
599 -- Check for all indexes static, and also compute possible
600 -- size (in case it is less than 32 and may be packable).
602 declare
606 begin
615 else
623 then
626 else
631 else
649 then
650 -- Don't do any recursion on type with error posted, since
651 -- we may have a malformed type that leads us into a loop
655 else
661 -- A class-wide type is never considered to have a known size
666 -- A subtype of a variant record must not have non-static
667 -- discriminanted components.
671 then
674 -- Don't do any recursion on type with error posted, since
675 -- we may have a malformed type that leads us into a loop
681 -- Now look at the components of the record
683 declare
684 -- The following two variables are used to keep track of
685 -- the size of packed records if we can tell the size of
686 -- the packed record in the front end. Packed_Size_Known
687 -- is True if so far we can figure out the size. It is
688 -- initialized to True for a packed record, unless the
689 -- record has discriminants. The reason we eliminate the
690 -- discriminated case is that we don't know the way the
691 -- back end lays out discriminated packed records. If
692 -- Packed_Size_Known is True, then Packed_Size is the
693 -- size in bits so far.
701 begin
702 -- Test for variant part present
708 N_Record_Definition
712 then
713 -- If variant part is present, and type is unconstrained,
714 -- then we must have defaulted discriminants, or a size
715 -- clause must be present for the type, or else the size
716 -- is definitely not known at compile time.
719 and then
720 No (Discriminant_Default_Value
723 then
728 -- Loop through components
733 or else
735 then
738 -- We do not know the packed size if there is a
739 -- component clause present (we possibly could,
740 -- but this would only help in the case of a record
741 -- with partial rep clauses. That's because in the
742 -- case of full rep clauses, the size gets figured
743 -- out anyway by a different circuit).
749 -- We need to identify a component that is an array
750 -- where the index type is an enumeration type with
751 -- non-standard representation, and some bound of the
752 -- type depends on a discriminant.
754 -- This is because gigi computes the size by doing a
755 -- substituation of the appropriate discriminant value
756 -- in the size expression for the base type, and gigi
757 -- is not clever enough to evaluate the resulting
758 -- expression (which involves a call to rep_to_pos)
759 -- at compile time.
761 -- It would be nice if gigi would either recognize that
762 -- this expression can be computed at compile time, or
763 -- alternatively figured out the size from the subtype
764 -- directly, where all the information is at hand ???
768 then
769 declare
777 begin
784 then
789 and then
791 then
795 and then
797 then
807 -- Clearly size of record is not known if the size of
808 -- one of the components is not known.
814 -- Accumulate packed size if possible
818 -- We can only deal with elementary types, since for
819 -- non-elementary components, alignment enters into
820 -- the picture, and we don't know enough to handle
821 -- proper alignment in this context. Packed arrays
822 -- count as elementary if the representation is a
823 -- modular type.
827 and then
829 and then
830 Is_Modular_Integer_Type
832 then
833 -- If RM_Size is known and static, then we can
834 -- keep accumulating the packed size.
838 -- A little glitch, to be removed sometime ???
839 -- gigi does not understand zero sizes yet.
844 -- Normal case where we can keep accumulating
845 -- the packed array size.
847 else
851 -- If we have a field whose RM_Size is not known
852 -- then we can't figure out the packed size here.
854 else
858 -- If we have a non-elementary type we can't figure
859 -- out the packed array size (alignment issues).
861 else
877 else
882 -------------------------------------
883 -- Static_Discriminated_Components --
884 -------------------------------------
886 function Static_Discriminated_Components
888 is
891 begin
895 then
909 -- Start of processing for Check_Compile_Time_Size
911 begin
915 -----------------------------
916 -- Check_Debug_Info_Needed --
917 -----------------------------
920 begin
925 or else Debug_Generated_Code
926 or else Debug_Flag_VV
927 then
932 ----------------------------
933 -- Check_Strict_Alignment --
934 ----------------------------
939 begin
958 then
968 -------------------------
969 -- Check_Unsigned_Type --
970 -------------------------
977 begin
982 -- Do not attempt to analyze case where range was in error
988 -- The situation that is non trivial is something like
990 -- subtype x1 is integer range -10 .. +10;
991 -- subtype x2 is x1 range 0 .. V1;
992 -- subtype x3 is x2 range V2 .. V3;
993 -- subtype x4 is x3 range V4 .. V5;
995 -- where Vn are variables. Here the base type is signed, but we still
996 -- know that x4 is unsigned because of the lower bound of x2.
998 -- The only way to deal with this is to look up the ancestor chain
1001 loop
1016 else
1019 -- If no ancestor had a static lower bound, go to base type
1023 -- Note: the reason we still check for a compile time known
1024 -- value for the base type is that at least in the case of
1025 -- generic formals, we can have bounds that fail this test,
1026 -- and there may be other cases in error situations.
1038 then
1048 -----------------------------
1049 -- Expand_Atomic_Aggregate --
1050 -----------------------------
1057 begin
1062 then
1063 Temp :=
1067 New_N :=
1077 -- To prevent the temporary from being constant-folded (which
1078 -- would lead to the same piecemeal assignment on the original
1079 -- target) indicate to the back-end that the temporary is a
1080 -- variable with real storage. See description of this flag
1081 -- in Einfo, and the notes on N_Assignment_Statement and
1082 -- N_Object_Declaration in Sinfo.
1088 ----------------
1089 -- Freeze_All --
1090 ----------------
1092 -- Note: the easy coding for this procedure would be to just build a
1093 -- single list of freeze nodes and then insert them and analyze them
1094 -- all at once. This won't work, because the analysis of earlier freeze
1095 -- nodes may recursively freeze types which would otherwise appear later
1096 -- on in the freeze list. So we must analyze and expand the freeze nodes
1097 -- as they are generated.
1105 -- This is the internal recursive routine that does freezing of
1106 -- entities (but NOT the analysis of default expressions, which
1107 -- should not be recursive, we don't want to analyze those till
1108 -- we are sure that ALL the types are frozen).
1110 --------------------
1111 -- Freeze_All_Ent --
1112 --------------------
1114 procedure Freeze_All_Ent
1117 is
1123 -- If freeze nodes are present, insert and analyze, and reset
1124 -- cursor for next insertion.
1126 -------------------
1127 -- Process_Flist --
1128 -------------------
1131 begin
1138 else
1144 -- Start or processing for Freeze_All_Ent
1146 begin
1150 -- If the entity is an inner package which is not a package
1151 -- renaming, then its entities must be frozen at this point.
1152 -- Note that such entities do NOT get frozen at the end of
1153 -- the nested package itself (only library packages freeze).
1155 -- Same is true for task declarations, where anonymous records
1156 -- created for entry parameters must be frozen.
1162 then
1172 and then
1174 or else
1176 then
1179 End_Scope;
1181 -- For a derived tagged type, we must ensure that all the
1182 -- primitive operations of the parent have been frozen, so
1183 -- that their addresses will be in the parent's dispatch table
1184 -- at the point it is inherited.
1190 then
1191 declare
1198 begin
1206 then
1208 Process_Flist;
1218 Process_Flist;
1221 -- If an incomplete type is still not frozen, this may be
1222 -- a premature freezing because of a body declaration that
1223 -- follows. Indicate where the freezing took place.
1225 -- If the freezing is caused by the end of the current
1226 -- declarative part, it is a Taft Amendment type, and there
1227 -- is no error.
1231 then
1232 declare
1235 begin
1242 and then
1244 then
1246 Error_Msg_NE
1257 -- Start of processing for Freeze_All
1259 begin
1262 -- Now that all types are frozen, we can deal with default expressions
1263 -- that require us to build a default expression functions. This is the
1264 -- point at which such functions are constructed (after all types that
1265 -- might be used in such expressions have been frozen).
1267 -- We also add finalization chains to access types whose designated
1268 -- types are controlled. This is normally done when freezing the type,
1269 -- but this misses recursive type definitions where the later members
1270 -- of the recursion introduce controlled components (e.g. 5624-001).
1272 -- Loop through entities
1290 and then
1292 = N_Subprogram_Renaming_Declaration
1293 then
1294 Build_And_Analyze_Renamed_Body
1300 and then
1302 or else
1304 then
1305 declare
1307 begin
1314 then
1327 then
1335 -----------------------
1336 -- Freeze_And_Append --
1337 -----------------------
1339 procedure Freeze_And_Append
1343 is
1345 begin
1349 else
1355 -------------------
1356 -- Freeze_Before --
1357 -------------------
1361 begin
1367 -------------------
1368 -- Freeze_Entity --
1369 -------------------
1381 -- Check that an Access or Unchecked_Access attribute with a prefix
1382 -- which is the current instance type can only be applied when the type
1383 -- is limited.
1386 -- If Loc is a freeze_entity that appears after the last declaration
1387 -- in the scope, inhibit error messages on late completion.
1390 -- Freeze each component, handle some representation clauses, and freeze
1391 -- primitive operations if this is a tagged type.
1393 ----------------------------
1394 -- After_Last_Declaration --
1395 ----------------------------
1400 begin
1407 else
1411 else
1416 ----------------------------
1417 -- Check_Current_Instance --
1418 ----------------------------
1423 -- Process routine to apply check to given node
1425 -------------
1426 -- Process --
1427 -------------
1430 begin
1434 or else
1439 then
1440 Error_Msg_N
1443 else
1453 -- Start of processing for Check_Current_Instance
1455 begin
1459 ------------------------
1460 -- Freeze_Record_Type --
1461 ------------------------
1471 -- Set True if we find at least one component with no component
1472 -- clause (used to warn about useless Pack pragmas).
1475 -- Set True if we find at least one component with a component
1476 -- clause (used to warn about useless Bit_Order pragmas).
1479 -- If the component subtype is an access to a constrained subtype
1480 -- of an already frozen type, make the subtype frozen as well. It
1481 -- might otherwise be frozen in the wrong scope, and a freeze node
1482 -- on subtype has no effect.
1484 -----------------
1485 -- Check_Itype --
1486 -----------------
1489 begin
1492 then
1495 -- In addition, add an Itype_Reference to ensure that the
1496 -- access subtype is elaborated early enough. This cannot
1497 -- be done if the subtype may depend on discriminants.
1502 then
1508 else
1515 -- Start of processing for Freeze_Record_Type
1517 begin
1518 -- If this is a subtype of a controlled type, declared without
1519 -- a constraint, the _controller may not appear in the component
1520 -- list if the parent was not frozen at the point of subtype
1521 -- declaration. Inherit the _controller component now.
1525 then
1528 then
1531 -- If this is an internal type without a declaration, as for
1532 -- record component, the base type may not yet be frozen, and its
1533 -- controller has not been created. Add an explicit freeze node
1534 -- for the itype, so it will be frozen after the base type. This
1535 -- freeze node is used to communicate with the expander, in order
1536 -- to create the controller for the enclosing record, and it is
1537 -- deleted afterwards (see exp_ch3). It must not be created when
1538 -- expansion is off, because it might appear in the wrong context
1539 -- for the back end.
1543 and then
1545 N_Component_Declaration
1546 and then Expander_Active
1547 then
1552 -- Freeze components and embedded subtypes
1558 -- First handle the (real) component case
1562 then
1563 declare
1566 begin
1567 -- Freezing a record type freezes the type of each of its
1568 -- components. However, if the type of the component is
1569 -- part of this record, we do not want or need a separate
1570 -- Freeze_Node. Note that Is_Itype is wrong because that's
1571 -- also set in private type cases. We also can't check for
1572 -- the Scope being exactly Rec because of private types and
1573 -- record extensions.
1578 then
1584 -- Check for error of component clause given for variable
1585 -- sized type. We have to delay this test till this point,
1586 -- since the component type has to be frozen for us to know
1587 -- if it is variable length. We omit this test in a generic
1588 -- context, it will be applied at instantiation time.
1596 elsif not Size_Known_At_Compile_Time
1598 then
1599 Error_Msg_N
1604 else
1608 -- Case of component requires byte alignment
1612 -- Set the enclosing record to also require byte align
1616 -- Check for component clause that is inconsistent
1617 -- with the required byte boundary alignment.
1622 then
1623 Error_Msg_N
1629 -- If component clause is present, then deal with the
1630 -- non-default bit order case. We cannot do this before
1631 -- the freeze point, because there is no required order
1632 -- for the component clause and the bit_order clause.
1634 -- We only do this processing for the base type, and in
1635 -- fact that's important, since otherwise if there are
1636 -- record subtypes, we could reverse the bits once for
1637 -- each subtype, which would be incorrect.
1642 then
1643 declare
1656 begin
1657 -- Cases where field goes over storage unit boundary
1661 -- Allow multi-byte field but generate warning
1665 then
1666 Error_Msg_N
1671 Error_Msg_N
1674 else
1675 Error_Msg_N
1680 -- Do not allow non-contiguous field
1682 else
1683 Error_Msg_N
1686 Error_Msg_N
1691 -- Case where field fits in one storage unit
1693 else
1694 -- Give warning if suspicious component clause
1697 Error_Msg_N
1700 Error_Msg_Uint_1 :=
1702 System_Storage_Unit;
1703 Error_Msg_N
1708 -- Here is where we fix up the Component_Bit_Offset
1709 -- value to account for the reverse bit order.
1710 -- Some examples of what needs to be done are:
1712 -- First_Bit .. Last_Bit Component_Bit_Offset
1713 -- old new old new
1715 -- 0 .. 0 7 .. 7 0 7
1716 -- 0 .. 1 6 .. 7 0 6
1717 -- 0 .. 2 5 .. 7 0 5
1718 -- 0 .. 7 0 .. 7 0 4
1720 -- 1 .. 1 6 .. 6 1 6
1721 -- 1 .. 4 3 .. 6 1 3
1722 -- 4 .. 7 0 .. 3 4 0
1724 -- The general rule is that the first bit is
1725 -- is obtained by subtracting the old ending bit
1726 -- from storage_unit - 1.
1728 Set_Component_Bit_Offset
1734 Set_Normalized_First_Bit
1737 System_Storage_Unit);
1744 -- If the component is an Itype with Delayed_Freeze and is either
1745 -- a record or array subtype and its base type has not yet been
1746 -- frozen, we must remove this from the entity list of this
1747 -- record and put it on the entity list of the scope of its base
1748 -- type. Note that we know that this is not the type of a
1749 -- component since we cleared Has_Delayed_Freeze for it in the
1750 -- previous loop. Thus this must be the Designated_Type of an
1751 -- access type, which is the type of a component.
1759 then
1760 declare
1764 begin
1765 -- We have a pretty bad kludge here. Suppose Rec is a
1766 -- subtype being defined in a subprogram that's created
1767 -- as part of the freezing of Rec'Base. In that case,
1768 -- we know that Comp'Base must have already been frozen by
1769 -- the time we get to elaborate this because Gigi doesn't
1770 -- elaborate any bodies until it has elaborated all of the
1771 -- declarative part. But Is_Frozen will not be set at this
1772 -- point because we are processing code in lexical order.
1774 -- We detect this case by going up the Scope chain of
1775 -- Rec and seeing if we have a subprogram scope before
1776 -- reaching the top of the scope chain or that of Comp'Base.
1777 -- If we do, then mark that Comp'Base will actually be
1778 -- frozen. If so, we merely undelay it.
1793 else
1796 else
1800 -- Insert in entity list of scope of base type (which
1801 -- must be an enclosing scope, because still unfrozen).
1807 -- If the component is an access type with an allocator as
1808 -- default value, the designated type will be frozen by the
1809 -- corresponding expression in init_proc. In order to place the
1810 -- freeze node for the designated type before that for the
1811 -- current record type, freeze it now.
1813 -- Same process if the component is an array of access types,
1814 -- initialized with an aggregate. If the designated type is
1815 -- private, it cannot contain allocators, and it is premature to
1816 -- freeze the type, so we check for this as well.
1822 then
1823 declare
1826 begin
1827 -- If component is pointer to a classwide type, freeze
1828 -- the specific type in the expression being allocated.
1829 -- The expression may be a subtype indication, in which
1830 -- case freeze the subtype mark.
1834 Freeze_And_Append
1836 elsif
1838 then
1839 Freeze_And_Append
1847 else
1848 Freeze_And_Append
1855 then
1864 and then Is_Fully_Defined
1866 then
1867 Freeze_And_Append
1868 (Designated_Type
1876 -- Check for useless pragma Bit_Order
1884 -- Check for useless pragma Pack when all components placed. We only
1885 -- do this check for record types, not subtypes, since a subtype may
1886 -- have all its components placed, and it still makes perfectly good
1887 -- sense to pack other subtypes or the parent type.
1891 and then not Unplaced_Component
1892 then
1893 -- Reset packed status. Probably not necessary, but we do it
1894 -- so that there is no chance of the back end doing something
1895 -- strange with this redundant indication of packing.
1899 -- Give warning if redundant constructs warnings on
1902 Error_Msg_N
1908 -- If this is the record corresponding to a remote type, freeze the
1909 -- remote type here since that is what we are semantically freezing.
1910 -- This prevents the freeze node for that type in an inner scope.
1912 -- Also, Check for controlled components and unchecked unions.
1913 -- Finally, enforce the restriction that access attributes with a
1914 -- current instance prefix can only apply to limited types.
1918 Freeze_And_Append
1928 and then Present
1930 and then Has_Controlled_Component
1932 then
1943 then
1944 -- Scan component declaration for likely misuses of current
1945 -- instance, either in a constraint or a default expression.
1956 -- For first subtypes, check if there are any fixed-point fields with
1957 -- component clauses, where we must check the size. This is not done
1958 -- till the freeze point, since for fixed-point types, we do not know
1959 -- the size until the type is frozen. Similar processing applies to
1960 -- bit packed arrays.
1968 or else
1970 then
1971 Check_Size
1975 Junk);
1983 -- Start of processing for Freeze_Entity
1985 begin
1986 -- We are going to test for various reasons why this entity need not be
1987 -- frozen here, but in the case of an Itype that's defined within a
1988 -- record, that test actually applies to the record.
1994 then
1998 -- Do not freeze if already frozen since we only need one freeze node
2003 -- It is improper to freeze an external entity within a generic because
2004 -- its freeze node will appear in a non-valid context. The entity will
2005 -- be frozen in the proper scope after the current generic is analyzed.
2010 -- Do not freeze a global entity within an inner scope created during
2011 -- expansion. A call to subprogram E within some internal procedure
2012 -- (a stream attribute for example) might require freezing E, but the
2013 -- freeze node must appear in the same declarative part as E itself.
2014 -- The two-pass elaboration mechanism in gigi guarantees that E will
2015 -- be frozen before the inner call is elaborated. We exclude constants
2016 -- from this test, because deferred constants may be frozen early, and
2017 -- must be diagnosed (see e.g. 1522-005). If the enclosing subprogram
2018 -- comes from source, or is a generic instance, then the freeze point
2019 -- is the one mandated by the language. and we freze the entity.
2024 then
2025 declare
2028 begin
2033 then
2035 else
2044 -- Similarly, an inlined instance body may make reference to global
2045 -- entities, but these references cannot be the proper freezing point
2046 -- for them, and the the absence of inlining freezing will take place
2047 -- in their own scope. Normally instance bodies are analyzed after
2048 -- the enclosing compilation, and everything has been frozen at the
2049 -- proper place, but with front-end inlining an instance body is
2050 -- compiled before the end of the enclosing scope, and as a result
2051 -- out-of-order freezing must be prevented.
2053 elsif Front_End_Inlining
2054 and then In_Instance_Body
2056 then
2057 declare
2060 begin
2064 else
2075 -- Here to freeze the entity
2080 -- Case of entity being frozen is other than a type
2084 -- If entity is exported or imported and does not have an external
2085 -- name, now is the time to provide the appropriate default name.
2086 -- Skip this if the entity is stubbed, since we don't need a name
2087 -- for any stubbed routine.
2092 then
2093 Set_Encoded_Interface_Name
2096 -- Special processing for atomic objects appearing in object decls
2101 then
2102 declare
2105 begin
2106 -- If expression is an aggregate, assign to a temporary to
2107 -- ensure that the actual assignment is done atomically rather
2108 -- than component-wise (the assignment to the temp may be done
2109 -- component-wise, but that is harmless.
2114 -- If the expression is a reference to a record or array object
2115 -- entity, then reset Is_True_Constant to False so that the
2116 -- compiler will not optimize away the intermediate object,
2117 -- which we need in this case for the same reason (to ensure
2118 -- that the actual assignment is atomic, rather than
2119 -- component-wise).
2123 or else
2125 then
2131 -- For a subprogram, freeze all parameter types and also the return
2132 -- type (RM 13.14(14)). However skip this for internal subprograms.
2133 -- This is also the point where any extra formal parameters are
2134 -- created since we now know whether the subprogram will use
2135 -- a foreign convention.
2139 declare
2144 -- Determines if given type entity is a fat pointer type
2145 -- used as an argument type or return type to a subprogram
2146 -- with C or C++ convention set.
2148 --------------------------
2149 -- Is_Fat_C_Access_Type --
2150 --------------------------
2153 begin
2155 or else
2161 begin
2162 -- Loop through formals
2174 then
2175 -- If the type of a formal is incomplete, subprogram
2176 -- is being frozen prematurely. Within an instance
2177 -- (but not within a wrapper package) this is an
2178 -- an artifact of our need to regard the end of an
2179 -- instantiation as a freeze point. Otherwise it is
2180 -- a definite error.
2182 -- and then not Is_Wrapper_Package (Current_Scope) ???
2190 Error_Msg
2192 Loc);
2196 -- Check bad use of fat C pointer
2200 then
2202 Error_Msg_N
2204 Formal);
2208 -- Check for unconstrained array in exported foreign
2209 -- convention case.
2215 and then Warn_On_Export_Import
2216 then
2219 -- If this is an inherited operation, place the
2220 -- warning on the derived type declaration, rather
2221 -- than on the original subprogram.
2224 N_Full_Type_Declaration
2225 then
2229 Error_Msg_NE
2232 else
2236 Error_Msg_NE
2239 Error_Msg_NE
2245 -- Ada 2005 (AI-326): Check wrong use of tag incomplete
2246 -- types with unknown discriminants. For example:
2248 -- type T (<>) is tagged;
2249 -- procedure P (X : access T); -- ERROR
2250 -- procedure P (X : T); -- ERROR
2261 and then Unknown_Discriminants_Present
2264 then
2265 Error_Msg_N
2277 -- Check return type
2282 if Warn_On_Export_Import
2284 then
2285 Error_Msg_N
2287 E);
2293 and then Warn_On_Export_Import
2294 then
2295 Error_Msg_N
2299 -- Ada 2005 (AI-326): Check wrong use of tagged
2300 -- incomplete type
2301 --
2302 -- type T is tagged;
2303 -- function F (X : Boolean) return T; -- ERROR
2308 then
2309 Error_Msg_N
2311 E);
2317 -- Must freeze its parent first if it is a derived subprogram
2323 -- If the return type requires a transient scope, and we are on
2324 -- a target allowing functions to return with a depressed stack
2325 -- pointer, then we mark the function as requiring this treatment.
2328 and then Functions_Return_By_DSP_On_Target
2330 then
2338 -- Here for other than a subprogram or type
2340 else
2341 -- If entity has a type, and it is not a generic unit, then
2342 -- freeze it first (RM 13.14(10))
2346 then
2350 -- Special processing for objects created by object declaration
2354 -- For object created by object declaration, perform required
2355 -- categorization (preelaborate and pure) checks. Defer these
2356 -- checks to freeze time since pragma Import inhibits default
2357 -- initialization and thus pragma Import affects these checks.
2361 -- If there is an address clause, check it is valid
2365 -- For imported objects, set Is_Public unless there is also
2366 -- an address clause, which means that there is no external
2367 -- symbol needed for the Import (Is_Public may still be set
2368 -- for other unrelated reasons). Note that we delayed this
2369 -- processing till freeze time so that we can be sure not
2370 -- to set the flag if there is an address clause. If there
2371 -- is such a clause, then the only purpose of the import
2372 -- pragma is to suppress implicit initialization.
2376 then
2381 -- Check that a constant which has a pragma Volatile[_Components]
2382 -- or Atomic[_Components] also has a pragma Import (RM C.6(13))
2384 -- Note: Atomic[_Components] also sets Volatile[_Components]
2389 then
2390 -- Make sure we actually have a pragma, and have not merely
2391 -- inherited the indication from elsewhere (e.g. an address
2392 -- clause, which is not good enough in RM terms!)
2395 or else
2397 then
2398 Error_Msg_N
2403 or else
2405 then
2406 Error_Msg_N
2412 -- Static objects require special handling
2416 then
2420 -- Remaining step is to layout objects
2423 or else
2425 or else
2427 or else
2429 then
2434 -- Case of a type or subtype being frozen
2436 else
2437 -- The type may be defined in a generic unit. This can occur when
2438 -- freezing a generic function that returns the type (which is
2439 -- defined in a parent unit). It is clearly meaningless to freeze
2440 -- this type. However, if it is a subtype, its size may be determi-
2441 -- nable and used in subsequent checks, so might as well try to
2442 -- compute it.
2446 then
2451 -- Deal with special cases of freezing for subtype
2455 -- If ancestor subtype present, freeze that first.
2456 -- Note that this will also get the base type frozen.
2463 -- Otherwise freeze the base type of the entity before
2464 -- freezing the entity itself, (RM 13.14(15)).
2470 -- For a derived type, freeze its parent type first (RM 13.14(15))
2477 -- For array type, freeze index types and component type first
2478 -- before freezing the array (RM 13.14(15)).
2481 declare
2486 -- Set true if any of the index types is an enumeration
2487 -- type with a non-standard representation.
2489 begin
2498 then
2505 -- Processing that is done only for base types
2509 -- Propagate flags for component type
2513 then
2521 -- If packing was requested or if the component size was set
2522 -- explicitly, then see if bit packing is required. This
2523 -- processing is only done for base types, since all the
2524 -- representation aspects involved are type-related. This
2525 -- is not just an optimization, if we start processing the
2526 -- subtypes, they intefere with the settings on the base
2527 -- type (this is because Is_Packed has a slightly different
2528 -- meaning before and after freezing).
2530 declare
2534 begin
2538 then
2547 else
2550 -- We can set the component size if it is less than
2551 -- 16, rounding it up to the next storage unit size.
2557 else
2561 -- Set component size up to match alignment if
2562 -- it would otherwise be less than the alignment.
2563 -- This deals with cases of types whose alignment
2564 -- exceeds their sizes (padded types).
2567 declare
2570 begin
2581 -- We set the component size for all cases 1-64
2585 -- Check for base type of 8,16,32 bits, where the
2586 -- subtype has a length one less than the base type
2587 -- and is unsigned (e.g. Natural subtype of Integer)
2589 -- In such cases, if a component size was not set
2590 -- explicitly, then generate a warning.
2594 and then
2597 then
2599 Pnod :=
2603 Error_Msg_N
2605 Pnod);
2606 Error_Msg_N
2608 Pnod);
2612 -- Actual packing is not needed for 8,16,32,64
2613 -- Also not needed for 24 if alignment is 1
2620 then
2621 -- Here the array was requested to be packed, but
2622 -- the packing request had no effect, so Is_Packed
2623 -- is reset.
2625 -- Note: semantically this means that we lose
2626 -- track of the fact that a derived type inherited
2627 -- a pack pragma that was non-effective, but that
2628 -- seems fine.
2630 -- We regard a Pack pragma as a request to set a
2631 -- representation characteristic, and this request
2632 -- may be ignored.
2636 -- In all other cases, packing is indeed needed
2638 else
2646 -- Processing that is done only for subtypes
2648 else
2649 -- Acquire alignment from base type
2656 -- For bit-packed arrays, check the size
2660 then
2661 declare
2665 begin
2666 -- It is not clear if it is possible to have no size
2667 -- clause at this stage, but this is not worth worrying
2668 -- about. Post the error on the entity name in the size
2669 -- clause if present, else on the type entity itself.
2673 else
2679 -- Check one common case of a size given where the array
2680 -- needs to be packed, but was not so the size cannot be
2681 -- honored. This would of course be caught by the backend,
2682 -- and indeed we don't catch all cases. The point is that
2683 -- we can give a better error message in those cases that
2684 -- we do catch with the circuitry here.
2686 declare
2690 begin
2698 then
2705 then
2706 declare
2713 -- What we are looking for here is the situation
2714 -- where the Esize given would be exactly right
2715 -- if there was a pragma Pack (resulting in the
2716 -- component size being the same as the RM_Size).
2717 -- Furthermore, the component type size must be
2718 -- an odd size (not a multiple of storage unit)
2720 begin
2723 then
2724 Error_Msg_NE
2727 Error_Msg_N
2736 -- If any of the index types was an enumeration type with
2737 -- a non-standard rep clause, then we indicate that the
2738 -- array type is always packed (even if it is not bit packed).
2747 -- If the array is packed, we must create the packed array
2748 -- type to be used to actually implement the type. This is
2749 -- only needed for real array types (not for string literal
2750 -- types, since they are present only for the front end).
2754 then
2758 -- Size information of packed array type is copied to the
2759 -- array type, since this is really the representation.
2765 -- For non-packed arrays set the alignment of the array
2766 -- to the alignment of the component type if it is unknown.
2767 -- Skip this in the atomic case, since atomic arrays may
2768 -- need larger alignments.
2777 then
2782 -- For a class-wide type, the corresponding specific type is
2783 -- frozen as well (RM 13.14(15))
2788 -- If the Class_Wide_Type is an Itype (when type is the anonymous
2789 -- parent of a derived type) and it is a library-level entity,
2790 -- generate an itype reference for it. Otherwise, its first
2791 -- explicit reference may be in an inner scope, which will be
2792 -- rejected by the back-end.
2796 then
2797 declare
2800 begin
2804 else
2810 -- The equivalent type associated with a class-wide subtype
2811 -- needs to be frozen to ensure that its layout is done.
2812 -- Class-wide subtypes are currently only frozen on targets
2813 -- requiring front-end layout (see New_Class_Wide_Subtype
2814 -- and Make_CW_Equivalent_Type in exp_util.adb).
2818 then
2822 -- For a record (sub)type, freeze all the component types (RM
2823 -- 13.14(15). We test for E_Record_(sub)Type here, rather than
2824 -- using Is_Record_Type, because we don't want to attempt the
2825 -- freeze for the case of a private type with record extension
2826 -- (we will do that later when the full type is frozen).
2830 then
2833 -- For a concurrent type, freeze corresponding record type. This
2834 -- does not correpond to any specific rule in the RM, but the
2835 -- record type is essentially part of the concurrent type.
2836 -- Freeze as well all local entities. This includes record types
2837 -- created for entry parameter blocks, and whatever local entities
2838 -- may appear in the private part.
2842 Freeze_And_Append
2855 then
2865 -- Private types are required to point to the same freeze node as
2866 -- their corresponding full views. The freeze node itself has to
2867 -- point to the partial view of the entity (because from the partial
2868 -- view, we can retrieve the full view, but not the reverse).
2869 -- However, in order to freeze correctly, we need to freeze the full
2870 -- view. If we are freezing at the end of a scope (or within the
2871 -- scope of the private type), the partial and full views will have
2872 -- been swapped, the full view appears first in the entity chain and
2873 -- the swapping mechanism ensures that the pointers are properly set
2874 -- (on scope exit).
2876 -- If we encounter the partial view before the full view (e.g. when
2877 -- freezing from another scope), we freeze the full view, and then
2878 -- set the pointers appropriately since we cannot rely on swapping to
2879 -- fix things up (subtypes in an outer scope might not get swapped).
2883 then
2884 -- Case of full view present
2888 -- If full view has already been frozen, then no further
2889 -- processing is required
2897 -- Otherwise freeze full view and patch the pointers so that
2898 -- the freeze node will elaborate both views in the back-end.
2900 else
2901 declare
2904 begin
2907 then
2908 Freeze_And_Append
2921 else
2922 -- {Incomplete,Private}_Subtypes
2923 -- with Full_Views constrained by discriminants
2934 -- AI-117 requires that the convention of a partial view be the
2935 -- same as the convention of the full view. Note that this is a
2936 -- recognized breach of privacy, but it's essential for logical
2937 -- consistency of representation, and the lack of a rule in
2938 -- RM95 was an oversight.
2945 -- Size information is copied from the full view to the
2946 -- incomplete or private view for consistency
2948 -- We skip this is the full view is not a type. This is very
2949 -- strange of course, and can only happen as a result of
2950 -- certain illegalities, such as a premature attempt to derive
2951 -- from an incomplete type.
2960 -- Case of no full view present. If entity is derived or subtype,
2961 -- it is safe to freeze, correctness depends on the frozen status
2962 -- of parent. Otherwise it is either premature usage, or a Taft
2963 -- amendment type, so diagnosis is at the point of use and the
2964 -- type might be frozen later.
2968 then
2971 else
2976 -- For access subprogram, freeze types of all formals, the return
2977 -- type was already frozen, since it is the Etype of the function.
2986 -- If the return type requires a transient scope, and we are on
2987 -- a target allowing functions to return with a depressed stack
2988 -- pointer, then we mark the function as requiring this treatment.
2990 if Functions_Return_By_DSP_On_Target
2992 then
2998 -- AI-326: Check wrong use of tag incomplete type
2999 --
3000 -- type T is tagged;
3001 -- type Acc is access function (X : T) return T; -- ERROR
3006 then
3007 Error_Msg_N
3011 -- For access to a protected subprogram, freeze the equivalent type
3012 -- (however this is not set if we are not generating code or if this
3013 -- is an anonymous type used just for resolution).
3017 -- AI-326: Check wrong use of tagged incomplete types
3019 -- type T is tagged;
3020 -- type As3D is access protected
3021 -- function (X : Float) return T; -- ERROR
3023 declare
3026 begin
3036 then
3037 Error_Msg_N
3047 -- Generic types are never seen by the back-end, and are also not
3048 -- processed by the expander (since the expander is turned off for
3049 -- generic processing), so we never need freeze nodes for them.
3055 -- Some special processing for non-generic types to complete
3056 -- representation details not known till the freeze point.
3061 -- Some error checks required for ordinary fixed-point type. Defer
3062 -- these till the freeze-point since we need the small and range
3063 -- values. We only do these checks for base types
3067 then
3070 Error_Msg_N
3075 Error_Msg_N
3081 Error_Msg_N
3087 Error_Msg_N
3100 -- Check restriction for standard storage pool
3106 -- Deal with error message for pure access type. This is not an
3107 -- error in Ada 2005 if there is no pool (see AI-366).
3112 then
3117 -- Case of composite types
3121 -- AI-117 requires that all new primitives of a tagged type must
3122 -- inherit the convention of the full view of the type. Inherited
3123 -- and overriding operations are defined to inherit the convention
3124 -- of their parent or overridden subprogram (also specified in
3125 -- AI-117), which will have occurred earlier (in Derive_Subprogram
3126 -- and New_Overloaded_Entity). Here we set the convention of
3127 -- primitives that are still convention Ada, which will ensure
3128 -- that any new primitives inherit the type's convention.
3129 -- Class-wide types can have a foreign convention inherited from
3130 -- their specific type, but are excluded from this since they
3131 -- don't have any associated primitives.
3136 then
3137 declare
3140 begin
3153 -- Generate primitive operation references for a tagged type
3157 then
3158 declare
3164 begin
3165 -- Handle subtypes
3169 then
3171 else
3175 -- Ada 2005 (AI-345): In case of concurrent type generate
3176 -- reference to the wrapper that allow us to dispatch calls
3177 -- through their implemented abstract interface types.
3179 -- The check for Present here is to protect against previously
3180 -- reported critical errors.
3184 then
3186 (Abstract_Interfaces
3189 Prim_List := Primitive_Operations
3191 else
3195 -- Loop to generate references for primitive operations
3201 -- If the operation is derived, get the original for
3202 -- cross-reference purposes (it is the original for
3203 -- which we want the xref, and for which the comes
3204 -- from source test needs to be performed).
3218 -- Now that all types from which E may depend are frozen, see if the
3219 -- size is known at compile time, if it must be unsigned, or if
3220 -- strict alignent is required
3229 -- Do not allow a size clause for a type which does not have a size
3230 -- that is known at compile time
3234 then
3235 -- Supress this message if errors posted on E, even if we are
3236 -- in all errors mode, since this is often a junk message
3239 Error_Msg_N
3245 -- Remaining process is to set/verify the representation information,
3246 -- in particular the size and alignment values. This processing is
3247 -- not required for generic types, since generic types do not play
3248 -- any part in code generation, and so the size and alignment values
3249 -- for such types are irrelevant.
3254 -- Otherwise we call the layout procedure
3256 else
3260 -- End of freeze processing for type entities
3263 -- Here is where we logically freeze the current entity. If it has a
3264 -- freeze node, then this is the point at which the freeze node is
3265 -- linked into the result list.
3269 -- If a freeze node is already allocated, use it, otherwise allocate
3270 -- a new one. The preallocation happens in the case of anonymous base
3271 -- types, where we preallocate so that we can set First_Subtype_Link.
3272 -- Note that we reset the Sloc to the current freeze location.
3278 else
3290 else
3294 -- A final pass over record types with discriminants. If the type
3295 -- has an incomplete declaration, there may be constrained access
3296 -- subtypes declared elsewhere, which do not depend on the discrimi-
3297 -- nants of the type, and which are used as component types (i.e.
3298 -- the full view is a recursive type). The designated types of these
3299 -- subtypes can only be elaborated after the type itself, and they
3300 -- need an itype reference.
3304 then
3305 declare
3310 begin
3321 then
3333 -- When a type is frozen, the first subtype of the type is frozen as
3334 -- well (RM 13.14(15)). This has to be done after freezing the type,
3335 -- since obviously the first subtype depends on its own base type.
3340 -- If we just froze a tagged non-class wide record, then freeze the
3341 -- corresponding class-wide type. This must be done after the tagged
3342 -- type itself is frozen, because the class-wide type refers to the
3343 -- tagged type which generates the class.
3348 then
3355 -- Special handling for subprograms
3359 -- If subprogram has address clause then reset Is_Public flag, since
3360 -- we do not want the backend to generate external references.
3364 then
3367 -- If no address clause and not intrinsic, then for imported
3368 -- subprogram in main unit, generate descriptor if we are in
3369 -- Propagate_Exceptions mode.
3371 elsif Propagate_Exceptions
3375 then
3385 -----------------------------
3386 -- Freeze_Enumeration_Type --
3387 -----------------------------
3390 begin
3394 then
3396 else
3401 -----------------------
3402 -- Freeze_Expression --
3403 -----------------------
3414 -- This flag is set true if the entity must be frozen outside the
3415 -- current subprogram. This happens in the case of expander generated
3416 -- subprograms (_Init_Proc, _Input, _Output, _Read, _Write) which do
3417 -- not freeze all entities like other bodies, but which nevertheless
3418 -- may reference entities that have to be frozen before the body and
3419 -- obviously cannot be frozen inside the body.
3422 -- Given an N_Handled_Sequence_Of_Statements node N, determines whether
3423 -- it is the handled statement sequence of an expander-generated
3424 -- subprogram (init proc, or stream subprogram). If so, it returns
3425 -- True, otherwise False.
3427 -----------------
3428 -- In_Exp_Body --
3429 -----------------
3434 begin
3437 else
3444 else
3453 then
3455 else
3461 -- Start of processing for Freeze_Expression
3463 begin
3464 -- Immediate return if freezing is inhibited. This flag is set by the
3465 -- analyzer to stop freezing on generated expressions that would cause
3466 -- freezing if they were in the source program, but which are not
3467 -- supposed to freeze, since they are created.
3473 -- If expression is non-static, then it does not freeze in a default
3474 -- expression, see section "Handling of Default Expressions" in the
3475 -- spec of package Sem for further details. Note that we have to
3476 -- make sure that we actually have a real expression (if we have
3477 -- a subtype indication, we can't test Is_Static_Expression!)
3479 if In_Def_Exp
3482 then
3486 -- Freeze type of expression if not frozen already
3494 -- Base type may be an derived numeric type that is frozen at
3495 -- the point of declaration, but first_subtype is still unfrozen.
3502 -- For entity name, freeze entity if not frozen already. A special
3503 -- exception occurs for an identifier that did not come from source.
3504 -- We don't let such identifiers freeze a non-internal entity, i.e.
3505 -- an entity that did come from source, since such an identifier was
3506 -- generated by the expander, and cannot have any semantic effect on
3507 -- the freezing semantics. For example, this stops the parameter of
3508 -- an initialization procedure from freezing the variable.
3515 then
3517 else
3521 -- For an allocator freeze designated type if not frozen already
3523 -- For an aggregate whose component type is an access type, freeze the
3524 -- designated type now, so that its freeze does not appear within the
3525 -- loop that might be created in the expansion of the aggregate. If the
3526 -- designated type is a private type without full view, the expression
3527 -- cannot contain an allocator, so the type is not frozen.
3538 then
3542 when N_Selected_Component |
3543 N_Indexed_Component |
3544 N_Slice =>
3557 then
3561 -- All done if nothing needs freezing
3566 then
3570 -- Loop for looking at the right place to insert the freeze nodes
3571 -- exiting from the loop when it is appropriate to insert the freeze
3572 -- node before the current node P.
3574 -- Also checks some special exceptions to the freezing rules. These
3575 -- cases result in a direct return, bypassing the freeze action.
3578 loop
3581 -- If we don't have a parent, then we are not in a well-formed tree.
3582 -- This is an unusual case, but there are some legitimate situations
3583 -- in which this occurs, notably when the expressions in the range of
3584 -- a type declaration are resolved. We simply ignore the freeze
3585 -- request in this case. Is this right ???
3591 -- See if we have got to an appropriate point in the tree
3595 -- A special test for the exception of (RM 13.14(8)) for the case
3596 -- of per-object expressions (RM 3.8(18)) occurring in component
3597 -- definition or a discrete subtype definition. Note that we test
3598 -- for a component declaration which includes both cases we are
3599 -- interested in, and furthermore the tree does not have explicit
3600 -- nodes for either of these two constructs.
3604 -- The case we want to test for here is an identifier that is
3605 -- a per-object expression, this is either a discriminant that
3606 -- appears in a context other than the component declaration
3607 -- or it is a reference to the type of the enclosing construct.
3609 -- For either of these cases, we skip the freezing
3611 if not In_Default_Expression
3614 then
3615 -- We recognize the discriminant case by just looking for
3616 -- a reference to a discriminant. It can only be one for
3617 -- the enclosing construct. Skip freezing in this case.
3622 -- For the case of a reference to the enclosing record,
3623 -- (or task or protected type), we look for a type that
3624 -- matches the current scope.
3631 -- If we have an enumeration literal that appears as the choice in
3632 -- the aggregate of an enumeration representation clause, then
3633 -- freezing does not occur (RM 13.14(10)).
3637 -- The case we are looking for is an enumeration literal
3641 then
3642 -- If enumeration literal appears directly as the choice,
3643 -- do not freeze (this is the normal non-overloade case)
3647 then
3650 -- If enumeration literal appears as the name of function
3651 -- which is the choice, then also do not freeze. This
3652 -- happens in the overloaded literal case, where the
3653 -- enumeration literal is temporarily changed to a function
3654 -- call for overloading analysis purposes.
3657 and then
3659 and then
3661 then
3666 -- Normally if the parent is a handled sequence of statements,
3667 -- then the current node must be a statement, and that is an
3668 -- appropriate place to insert a freeze node.
3672 -- An exception occurs when the sequence of statements is for
3673 -- an expander generated body that did not do the usual freeze
3674 -- all operation. In this case we usually want to freeze
3675 -- outside this body, not inside it, and we skip past the
3676 -- subprogram body that we are inside.
3680 -- However, we *do* want to freeze at this point if we have
3681 -- an entity to freeze, and that entity is declared *inside*
3682 -- the body of the expander generated procedure. This case
3683 -- is recognized by the scope of the type, which is either
3684 -- the spec for some enclosing body, or (in the case of
3685 -- init_procs, for which there are no separate specs) the
3686 -- current scope.
3688 declare
3692 begin
3697 or else
3699 then
3705 then
3711 -- If not that exception to the exception, then this is
3712 -- where we delay the freeze till outside the body.
3717 -- Here if normal case where we are in handled statement
3718 -- sequence and want to do the insertion right there.
3720 else
3724 -- If parent is a body or a spec or a block, then the current node
3725 -- is a statement or declaration and we can insert the freeze node
3726 -- before it.
3728 when N_Package_Specification |
3729 N_Package_Body |
3730 N_Subprogram_Body |
3731 N_Task_Body |
3732 N_Protected_Body |
3733 N_Entry_Body |
3736 -- The expander is allowed to define types in any statements list,
3737 -- so any of the following parent nodes also mark a freezing point
3738 -- if the actual node is in a list of statements or declarations.
3740 when N_Exception_Handler |
3741 N_If_Statement |
3742 N_Elsif_Part |
3743 N_Case_Statement_Alternative |
3744 N_Compilation_Unit_Aux |
3745 N_Selective_Accept |
3746 N_Accept_Alternative |
3747 N_Delay_Alternative |
3748 N_Conditional_Entry_Call |
3749 N_Entry_Call_Alternative |
3750 N_Triggering_Alternative |
3751 N_Abortable_Part |
3752 N_Freeze_Entity =>
3756 -- Note: The N_Loop_Statement is a special case. A type that
3757 -- appears in the source can never be frozen in a loop (this
3758 -- occurs only because of a loop expanded by the expander), so we
3759 -- keep on going. Otherwise we terminate the search. Same is true
3760 -- of any entity which comes from source. (if they have predefined
3761 -- type, that type does not appear to come from source, but the
3762 -- entity should not be frozen here).
3768 -- For all other cases, keep looking at parents
3774 -- We fall through the case if we did not yet find the proper
3775 -- place in the free for inserting the freeze node, so climb!
3780 -- If the expression appears in a record or an initialization procedure,
3781 -- the freeze nodes are collected and attached to the current scope, to
3782 -- be inserted and analyzed on exit from the scope, to insure that
3783 -- generated entities appear in the correct scope. If the expression is
3784 -- a default for a discriminant specification, the scope is still void.
3785 -- The expression can also appear in the discriminant part of a private
3786 -- or concurrent type.
3788 -- If the expression appears in a constrained subcomponent of an
3789 -- enclosing record declaration, the freeze nodes must be attached to
3790 -- the outer record type so they can eventually be placed in the
3791 -- enclosing declaration list.
3793 -- The other case requiring this special handling is if we are in a
3794 -- default expression, since in that case we are about to freeze a
3795 -- static type, and the freeze scope needs to be the outer scope, not
3796 -- the scope of the subprogram with the default parameter.
3798 -- For default expressions in generic units, the Move_Freeze_Nodes
3799 -- mechanism (see sem_ch12.adb) takes care of placing them at the proper
3800 -- place, after the generic unit.
3803 or else Freeze_Outside
3808 then
3809 declare
3814 begin
3827 -- The current scope may be that of a constrained component of
3828 -- an enclosing record declaration, which is above the current
3829 -- scope in the scope stack.
3838 Freeze_Nodes;
3839 else
3849 -- Now we have the right place to do the freezing. First, a special
3850 -- adjustment, if we are in default expression analysis mode, these
3851 -- freeze actions must not be thrown away (normally all inserted actions
3852 -- are thrown away in this mode. However, the freeze actions are from
3853 -- static expressions and one of the important reasons we are doing this
3854 -- special analysis is to get these freeze actions. Therefore we turn
3855 -- off the In_Default_Expression mode to propagate these freeze actions.
3856 -- This also means they get properly analyzed and expanded.
3860 -- Freeze the designated type of an allocator (RM 13.14(13))
3866 -- Freeze type of expression (RM 13.14(10)). Note that we took care of
3867 -- the enumeration representation clause exception in the loop above.
3873 -- Freeze name if one is present (RM 13.14(11))
3882 -----------------------------
3883 -- Freeze_Fixed_Point_Type --
3884 -----------------------------
3886 -- Certain fixed-point types and subtypes, including implicit base types
3887 -- and declared first subtypes, have not yet set up a range. This is
3888 -- because the range cannot be set until the Small and Size values are
3889 -- known, and these are not known till the type is frozen.
3891 -- To signal this case, Scalar_Range contains an unanalyzed syntactic range
3892 -- whose bounds are unanalyzed real literals. This routine will recognize
3893 -- this case, and transform this range node into a properly typed range
3894 -- with properly analyzed and resolved values.
3912 -- Returns size of type with given bounds. Also leaves these
3913 -- bounds set as the current bounds of the Typ.
3915 -----------
3916 -- Fsize --
3917 -----------
3920 begin
3926 -- Start of processing for Freeze_Fixed_Point_Type
3928 begin
3929 -- If Esize of a subtype has not previously been set, set it now
3936 else
3941 -- Immediate return if the range is already analyzed. This means that
3942 -- the range is already set, and does not need to be computed by this
3943 -- routine.
3949 -- Immediate return if either of the bounds raises Constraint_Error
3953 then
3960 -- Ordinary fixed-point case
3964 -- For the ordinary fixed-point case, we are allowed to fudge the
3965 -- end-points up or down by small. Generally we prefer to fudge up,
3966 -- i.e. widen the bounds for non-model numbers so that the end points
3967 -- are included. However there are cases in which this cannot be
3968 -- done, and indeed cases in which we may need to narrow the bounds.
3969 -- The following circuit makes the decision.
3971 -- Note: our terminology here is that Incl_EP means that the bounds
3972 -- are widened by Small if necessary to include the end points, and
3973 -- Excl_EP means that the bounds are narrowed by Small to exclude the
3974 -- end-points if this reduces the size.
3976 -- Note that in the Incl case, all we care about is including the
3977 -- end-points. In the Excl case, we want to narrow the bounds as
3978 -- much as permitted by the RM, to give the smallest possible size.
3995 begin
3996 -- First step. Base types are required to be symmetrical. Right
3997 -- now, the base type range is a copy of the first subtype range.
3998 -- This will be corrected before we are done, but right away we
3999 -- need to deal with the case where both bounds are non-negative.
4000 -- In this case, we set the low bound to the negative of the high
4001 -- bound, to make sure that the size is computed to include the
4002 -- required sign. Note that we do not need to worry about the
4003 -- case of both bounds negative, because the sign will be dealt
4004 -- with anyway. Furthermore we can't just go making such a bound
4005 -- symmetrical, since in a twos-complement system, there is an
4006 -- extra negative value which could not be accomodated on the
4007 -- positive side.
4012 then
4017 -- Compute the fudged bounds. If the number is a model number,
4018 -- then we do nothing to include it, but we are allowed to backoff
4019 -- to the next adjacent model number when we exclude it. If it is
4020 -- not a model number then we straddle the two values with the
4021 -- model numbers on either side.
4027 else
4031 -- The low value excluding the end point is Small greater, but
4032 -- we do not do this exclusion if the low value is positive,
4033 -- since it can't help the size and could actually hurt by
4034 -- crossing the high bound.
4038 else
4042 -- Similar processing for upper bound and high value
4048 else
4054 else
4058 -- One further adjustment is needed. In the case of subtypes, we
4059 -- cannot go outside the range of the base type, or we get
4060 -- peculiarities, and the base type range is already set. This
4061 -- only applies to the Incl values, since clearly the Excl values
4062 -- are already as restricted as they are allowed to be.
4069 -- Get size including and excluding end points
4074 -- No need to exclude end-points if it does not reduce size
4084 -- Now we set the actual size to be used. We want to use the
4085 -- bounds fudged up to include the end-points but only if this
4086 -- can be done without violating a specifically given size
4087 -- size clause or causing an unacceptable increase in size.
4089 -- Case of size clause given
4093 -- Use the inclusive size only if it is consistent with
4094 -- the explicitly specified size.
4101 -- If the inclusive size is too large, we try excluding
4102 -- the end-points (will be caught later if does not work).
4104 else
4110 -- Case of size clause not given
4112 else
4113 -- If we have a base type whose corresponding first subtype
4114 -- has an explicit size that is large enough to include our
4115 -- end-points, then do so. There is no point in working hard
4116 -- to get a base type whose size is smaller than the specified
4117 -- size of the first subtype.
4123 then
4128 -- If excluding the end-points makes the size smaller and
4129 -- results in a size of 8,16,32,64, then we take the smaller
4130 -- size. For the 64 case, this is compulsory. For the other
4131 -- cases, it seems reasonable. We like to include end points
4132 -- if we can, but not at the expense of moving to the next
4133 -- natural boundary of size.
4136 and then
4141 then
4146 -- Otherwise we can definitely include the end points
4148 else
4154 -- One pathological case: normally we never fudge a low bound
4155 -- down, since it would seem to increase the size (if it has
4156 -- any effect), but for ranges containing single value, or no
4157 -- values, the high bound can be small too large. Consider:
4159 -- type t is delta 2.0**(-14)
4160 -- range 131072.0 .. 0;
4162 -- That lower bound is *just* outside the range of 32 bits, and
4163 -- does need fudging down in this case. Note that the bounds
4164 -- will always have crossed here, since the high bound will be
4165 -- fudged down if necessary, as in the case of:
4167 -- type t is delta 2.0**(-14)
4168 -- range 131072.0 .. 131072.0;
4170 -- So we detect the situation by looking for crossed bounds,
4171 -- and if the bounds are crossed, and the low bound is greater
4172 -- than zero, we will always back it off by small, since this
4173 -- is completely harmless.
4180 -- And of course, we need to do exactly the same parallel
4181 -- fudge for flat ranges in the negative region.
4194 -- For the decimal case, none of this fudging is required, since there
4195 -- are no end-point problems in the decimal case (the end-points are
4196 -- always included).
4198 else
4202 -- At this stage, the actual size has been calculated and the proper
4203 -- required bounds are stored in the low and high bounds.
4207 Error_Msg_N
4212 -- Check size against explicit given size
4218 Error_Msg_NE
4222 else
4226 -- Increase size to next natural boundary if no size clause given
4228 else
4235 else
4243 -- If we have a base type, then expand the bounds so that they extend to
4244 -- the full width of the allocated size in bits, to avoid junk range
4245 -- checks on intermediate computations.
4252 -- Final step is to reanalyze the bounds using the proper type
4253 -- and set the Corresponding_Integer_Value fields of the literals.
4259 -- Resolve with universal fixed if the base type, and the base type if
4260 -- it is a subtype. Note we can't resolve the base type with itself,
4261 -- that would be a reference before definition.
4265 else
4269 -- Set corresponding integer value for bound
4271 Set_Corresponding_Integer_Value
4274 -- Similar processing for high bound
4282 else
4286 Set_Corresponding_Integer_Value
4289 -- Set type of range to correspond to bounds
4293 -- Set Esize to calculated size if not set already
4299 -- Set RM_Size if not already set. If already set, check value
4301 declare
4304 begin
4309 Error_Msg_NE
4314 else
4320 ------------------
4321 -- Freeze_Itype --
4322 ------------------
4327 begin
4336 --------------------------
4337 -- Freeze_Static_Object --
4338 --------------------------
4343 -- Exception raised if the type of a static object cannot be made
4344 -- static. This happens if the type depends on non-global objects.
4347 -- Called to ensure that an expression used as part of a type definition
4348 -- is statically allocatable, which means that the expression type is
4349 -- statically allocatable, and the expression is either static, or a
4350 -- reference to a library level constant.
4353 -- Called to mark a type as static, checking that it is possible
4354 -- to set the type as static. If it is not possible, then the
4355 -- exception Cannot_Be_Static is raised.
4357 -----------------------------
4358 -- Ensure_Expression_Is_SA --
4359 -----------------------------
4364 begin
4376 then
4384 -----------------------
4385 -- Ensure_Type_Is_SA --
4386 -----------------------
4392 begin
4393 -- If type is library level, we are all set
4399 -- We are also OK if the type already marked as statically allocated,
4400 -- which means we processed it before.
4406 -- Mark type as statically allocated
4410 -- Check that it is safe to statically allocate this type
4428 declare
4432 begin
4445 else
4455 then
4474 else
4479 -- Start of processing for Freeze_Static_Object
4481 begin
4484 -- Reset True_Constant flag, since something strange is going on with
4485 -- the scoping here, and our simple value tracing may not be sufficient
4486 -- for this indication to be reliable. We kill the Constant_Value
4487 -- indication for the same reason.
4492 exception
4495 -- If the object that cannot be static is imported or exported,
4496 -- then we give an error message saying that this object cannot
4497 -- be imported or exported.
4500 Error_Msg_N
4503 -- Otherwise must be exported, something is wrong if compiler
4504 -- is marking something as statically allocated which cannot be).
4507 Error_Msg_N
4512 -----------------------
4513 -- Freeze_Subprogram --
4514 -----------------------
4520 begin
4521 -- Subprogram may not have an address clause unless it is imported
4525 Error_Msg_N
4532 -- Reset the Pure indication on an imported subprogram unless an
4533 -- explicit Pure_Function pragma was present. We do this because
4534 -- otherwise it is an insidious error to call a non-pure function from
4535 -- pure unit and have calls mysteriously optimized away. What happens
4536 -- here is that the Import can bypass the normal check to ensure that
4537 -- pure units call only pure subprograms.
4542 then
4546 -- For non-foreign convention subprograms, this is where we create
4547 -- the extra formals (for accessibility level and constrained bit
4548 -- information). We delay this till the freeze point precisely so
4549 -- that we know the convention!
4555 -- If this is convention Ada and a Valued_Procedure, that's odd
4560 and then Warn_On_Export_Import
4561 then
4562 Error_Msg_N
4567 -- Case of foreign convention
4569 else
4572 -- For foreign conventions, warn about return of an
4573 -- unconstrained array.
4575 -- Note: we *do* allow a return by descriptor for the VMS case,
4576 -- though here there is probably more to be done ???
4581 -- If no return type, probably some other error, e.g. a
4582 -- missing full declaration, so ignore.
4587 -- If the return type is generic, we have emitted a warning
4588 -- earlier on, and there is nothing else to check here. Specific
4589 -- instantiations may lead to erroneous behavior.
4597 and then Warn_On_Export_Import
4598 then
4599 Error_Msg_N
4606 -- If any of the formals for an exported foreign convention
4607 -- subprogram have defaults, then emit an appropriate warning since
4608 -- this is odd (default cannot be used from non-Ada code)
4613 if Warn_On_Export_Import
4615 then
4616 Error_Msg_N
4626 -- For VMS, descriptor mechanisms for parameters are allowed only
4627 -- for imported subprograms.
4634 Error_Msg_N
4636 Error_Msg_N
4645 -- Pragma Inline_Always is disallowed for dispatching subprograms
4646 -- because the address of such subprograms is saved in the dispatch
4647 -- table to support dispatching calls, and dispatching calls cannot
4648 -- be inlined. This is consistent with the restriction against using
4649 -- 'Access or 'Address on an Inline_Always subprogram.
4652 Error_Msg_N
4657 ----------------------
4658 -- Is_Fully_Defined --
4659 ----------------------
4662 begin
4671 then
4672 -- Verify that the record type has no components with private types
4673 -- without completion.
4675 declare
4678 begin
4696 ---------------------------------
4697 -- Process_Default_Expressions --
4698 ---------------------------------
4700 procedure Process_Default_Expressions
4703 is
4710 begin
4713 -- A subprogram instance and its associated anonymous subprogram share
4714 -- their signature. The default expression functions are defined in the
4715 -- wrapper packages for the anonymous subprogram, and should not be
4716 -- generated again for the instance.
4721 then
4730 -- We work with a copy of the default expression because we
4731 -- do not want to disturb the original, since this would mess
4732 -- up the conformance checking.
4736 -- The analysis of the expression may generate insert actions,
4737 -- which of course must not be executed. We wrap those actions
4738 -- in a procedure that is not called, and later on eliminated.
4739 -- The following cases have no side-effects, and are analyzed
4740 -- directly.
4751 and then
4753 then
4755 -- If there is no default function, we must still do a full
4756 -- analyze call on the default value, to ensure that all error
4757 -- checks are performed, e.g. those associated with static
4758 -- evaluation. Note: this branch will always be taken if the
4759 -- analyzer is turned off (but we still need the error checks).
4761 -- Note: the setting of parent here is to meet the requirement
4762 -- that we can only analyze the expression while attached to
4763 -- the tree. Really the requirement is that the parent chain
4764 -- be set, we don't actually need to be in the tree.
4769 -- Default expressions are resolved with their own type if the
4770 -- context is generic, to avoid anomalies with private types.
4774 else
4778 -- If that resolved expression will raise constraint error,
4779 -- then flag the default value as raising constraint error.
4780 -- This allows a proper error message on the calls.
4786 -- If the default is a parameterless call, we use the name of
4787 -- the called function directly, and there is no body to build.
4791 then
4794 -- Else construct and analyze the body of a wrapper procedure
4795 -- that contains an object declaration to hold the expression.
4796 -- Given that this is done only to complete the analysis, it
4797 -- simpler to build a procedure than a function which might
4798 -- involve secondary stack expansion.
4800 else
4801 Dnam :=
4804 Dbody :=
4806 Specification =>
4812 Defining_Identifier =>
4815 Object_Definition =>
4819 Handled_Statement_Sequence =>
4837 ----------------------------------------
4838 -- Set_Component_Alignment_If_Not_Set --
4839 ----------------------------------------
4842 begin
4843 -- Ignore if not base type, subtypes don't need anything
4849 -- Do not override existing representation
4860 else
4861 Set_Component_Alignment
4867 ---------------------------
4868 -- Set_Debug_Info_Needed --
4869 ---------------------------
4872 begin
4876 then
4878 else
4889 declare
4891 begin
4901 declare
4903 begin
4926 ------------------
4927 -- Undelay_Type --
4928 ------------------
4931 begin
4935 -- Since we don't want T to have a Freeze_Node, we don't want its
4936 -- Full_View or Corresponding_Record_Type to have one either.
4938 -- ??? Fundamentally, this whole handling is a kludge. What we really
4939 -- want is to be sure that for an Itype that's part of record R and is a
4940 -- subtype of type T, that it's frozen after the later of the freeze
4941 -- points of R and T. We have no way of doing that directly, so what we
4942 -- do is force most such Itypes to be frozen as part of freezing R via
4943 -- this procedure and only delay the ones that need to be delayed
4944 -- (mostly the designated types of access types that are defined as part
4945 -- of the record).
4951 then
4959 then
4964 ------------------
4965 -- Warn_Overlay --
4966 ------------------
4968 procedure Warn_Overlay
4972 is
4974 -- The object to which the address clause applies
4980 begin
4981 -- No warning if address clause overlay warnings are off
4987 -- No warning if there is an explicit initialization
4995 -- We only give the warning for non-imported entities of a type for
4996 -- which a non-null base init proc is defined (or for access types which
4997 -- have implicit null initialization).
5003 then
5006 then
5011 then
5018 then
5025 -- A function call (most likely to To_Address) is probably not an
5026 -- overlay, so skip warning. Ditto if the function call was inlined
5027 -- and transformed into an entity.
5035 -- If a pragma Import follows, we assume that it is for the current
5036 -- target of the address clause, and skip the warning.
5041 then
5047 Error_Msg_N
5049 Nam);
5050 else
5051 Error_Msg_N
5053 Nam);
5056 -- Add friendly warning if initialization comes from a packed array
5057 -- component.
5060 declare
5063 begin
5069 then
5073 then
5074 Error_Msg_NE
5078 else
5085 Error_Msg_N
5088 Nam);