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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- F R E E Z E --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2004, 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, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, 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 ------------------------------------------------------------------------------
66 -----------------------
67 -- Local Subprograms --
68 -----------------------
71 -- Typ is a type that is being frozen. If no size clause is given,
72 -- but a default Esize has been computed, then this default Esize is
73 -- adjusted up if necessary to be consistent with a given alignment,
74 -- but never to a value greater than Long_Long_Integer'Size. This
75 -- is used for all discrete types and for fixed-point types.
77 procedure Build_And_Analyze_Renamed_Body
81 -- Build body for a renaming declaration, insert in tree and analyze.
84 -- Apply legality checks to address clauses for object declarations,
85 -- at the point the object is frozen.
88 -- E is a base type. If E is tagged or has a component that is aliased
89 -- or tagged or contains something this is aliased or tagged, set
90 -- Strict_Alignment.
94 -- If E is a fixed-point or discrete type, then all the necessary work
95 -- to freeze it is completed except for possible setting of the flag
96 -- Is_Unsigned_Type, which is done by this procedure. The call has no
97 -- effect if the entity E is not a discrete or fixed-point type.
99 procedure Freeze_And_Append
103 -- Freezes Ent using Freeze_Entity, and appends the resulting list of
104 -- nodes to Result, modifying Result from No_List if necessary.
107 -- Freeze enumeration type. The Esize field is set as processing
108 -- proceeds (i.e. set by default when the type is declared and then
109 -- adjusted by rep clauses. What this procedure does is to make sure
110 -- that if a foreign convention is specified, and no specific size
111 -- is given, then the size must be at least Integer'Size.
114 -- If an object is frozen which has Is_Statically_Allocated set, then
115 -- all referenced types must also be marked with this flag. This routine
116 -- is in charge of meeting this requirement for the object entity E.
119 -- Perform freezing actions for a subprogram (create extra formals,
120 -- and set proper default mechanism values). Note that this routine
121 -- is not called for internal subprograms, for which neither of these
122 -- actions is needed (or desirable, we do not want for example to have
123 -- these extra formals present in initialization procedures, where they
124 -- would serve no purpose). In this call E is either a subprogram or
125 -- a subprogram type (i.e. an access to a subprogram).
128 -- True if T is not private and has no private components, or has a full
129 -- view. Used to determine whether the designated type of an access type
130 -- should be frozen when the access type is frozen. This is done when an
131 -- allocator is frozen, or an expression that may involve attributes of
132 -- the designated type. Otherwise freezing the access type does not freeze
133 -- the designated type.
135 procedure Process_Default_Expressions
138 -- This procedure is called for each subprogram to complete processing
139 -- of default expressions at the point where all types are known to be
140 -- frozen. The expressions must be analyzed in full, to make sure that
141 -- all error processing is done (they have only been pre-analyzed). If
142 -- the expression is not an entity or literal, its analysis may generate
143 -- code which must not be executed. In that case we build a function
144 -- body to hold that code. This wrapper function serves no other purpose
145 -- (it used to be called to evaluate the default, but now the default is
146 -- inlined at each point of call).
149 -- Typ is a record or array type that is being frozen. This routine
150 -- sets the default component alignment from the scope stack values
151 -- if the alignment is otherwise not specified.
154 -- As each entity is frozen, this routine is called to deal with the
155 -- setting of Debug_Info_Needed for the entity. This flag is set if
156 -- the entity comes from source, or if we are in Debug_Generated_Code
157 -- mode or if the -gnatdV debug flag is set. However, it never sets
158 -- the flag if Debug_Info_Off is set.
161 -- Sets the Debug_Info_Needed flag on entity T if not already set, and
162 -- also on any entities that are needed by T (for an object, the type
163 -- of the object is needed, and for a type, the subsidiary types are
164 -- needed -- see body for details). Never has any effect on T if the
165 -- Debug_Info_Off flag is set.
167 procedure Warn_Overlay
171 -- Expr is the expression for an address clause for entity Nam whose type
172 -- is Typ. If Typ has a default initialization, and there is no explicit
173 -- initialization in the source declaration, check whether the address
174 -- clause might cause overlaying of an entity, and emit a warning on the
175 -- side effect that the initialization will cause.
177 -------------------------------
178 -- Adjust_Esize_For_Alignment --
179 -------------------------------
184 begin
190 then
196 ------------------------------------
197 -- Build_And_Analyze_Renamed_Body --
198 ------------------------------------
200 procedure Build_And_Analyze_Renamed_Body
204 is
207 begin
214 ------------------------
215 -- Build_Renamed_Body --
216 ------------------------
218 function Build_Renamed_Body
221 is
223 -- We use for the source location of the renamed body, the location
224 -- of the spec entity. It might seem more natural to use the location
225 -- of the renaming declaration itself, but that would be wrong, since
226 -- then the body we create would look as though it was created far
227 -- too late, and this could cause problems with elaboration order
228 -- analysis, particularly in connection with instantiations.
242 begin
243 -- Determine the entity being renamed, which is the target of the
244 -- call statement. If the name is an explicit dereference, this is
245 -- a renaming of a subprogram type rather than a subprogram. The
246 -- name itself is fully analyzed.
257 else
264 else
270 -- If the renamed entity is a predefined operator, retain full
271 -- name to ensure its visibility.
275 then
277 else
281 else
284 -- The original name may have been overloaded, but
285 -- is fully resolved now.
290 -- For simple renamings, subsequent calls can be expanded directly
291 -- as called to the renamed entity. The body must be generated in
292 -- any case for calls they may appear elsewhere.
297 then
301 -- The body generated for this renaming is an internal artifact, and
302 -- does not constitute a freeze point for the called entity.
317 -- If the renamed entity is an entry, inherit its profile. For
318 -- other renamings as bodies, both profiles must be subtype
319 -- conformant, so it is not necessary to replace the profile given
320 -- in the declaration. However, default values that are aggregates
321 -- are rewritten when partially analyzed, so we recover the original
322 -- aggregate to insure that subsequent conformity checking works.
323 -- Similarly, if the default expression was constant-folded, recover
324 -- the original expression.
336 N_Access_Definition
337 then
345 then
356 -- If the renamed entity is a function, the generated body contains a
357 -- return statement. Otherwise, build a procedure call. If the entity is
358 -- an entry, subsequent analysis of the call will transform it into the
359 -- proper entry or protected operation call. If the renamed entity is
360 -- a character literal, return it directly.
366 then
367 Call_Node :=
369 Expression =>
375 Call_Node :=
380 Call_Node :=
384 else
385 Call_Node :=
391 -- Create entities for subprogram body and formals.
405 Body_Node :=
409 Handled_Statement_Sequence =>
419 -- Link the body to the entity whose declaration it completes. If
420 -- the body is analyzed when the renamed entity is frozen, it may be
421 -- necessary to restore the proper scope (see package Exp_Ch13).
425 then
427 else
434 --------------------------
435 -- Check_Address_Clause --
436 --------------------------
444 begin
448 -- If we have no initialization of any kind, then we don't
449 -- need to place any restrictions on the address clause, because
450 -- the object will be elaborated after the address clause is
451 -- evaluated. This happens if the declaration has no initial
452 -- expression, or the type has no implicit initialization, or
453 -- the object is imported.
455 -- The same holds for all initialized scalar types and all
456 -- access types. Packed bit arrays of size up to 64 are
457 -- represented using a modular type with an initialization
458 -- (to zero) and can be processed like other initialized
459 -- scalar types.
461 -- If the type is controlled, code to attach the object to a
462 -- finalization chain is generated at the point of declaration,
463 -- and therefore the elaboration of the object cannot be delayed:
464 -- the address expression must be a constant.
468 and then
472 or else
476 or else
479 or else
481 and then
483 then
486 -- Otherwise, we require the address clause to be constant
487 -- because the call to the initialization procedure (or the
488 -- attach code) has to happen at the point of the declaration.
490 else
497 then
503 -----------------------------
504 -- Check_Compile_Time_Size --
505 -----------------------------
510 -- Sets the compile time known size (32 bits or less) in the Esize
511 -- field, checking for a size clause that was given which attempts
512 -- to give a smaller size.
515 -- Recursive function that does all the work
518 -- If T is a constrained subtype, its size is not known if any of its
519 -- discriminant constraints is not static and it is not a null record.
520 -- The test is conservative and doesn't check that the components are
521 -- in fact constrained by non-static discriminant values. Could be made
522 -- more precise ???
524 --------------------
525 -- Set_Small_Size --
526 --------------------
529 begin
536 Error_Msg_NE
544 -- Set sizes if not set already
546 else
557 ----------------
558 -- Size_Known --
559 ----------------
568 begin
574 then
585 -- Don't do any recursion on type with error posted, since
586 -- we may have a malformed type that leads us into a loop
595 -- Check for all indexes static, and also compute possible
596 -- size (in case it is less than 32 and may be packable).
598 declare
602 begin
611 else
619 then
622 else
627 else
645 then
646 -- Don't do any recursion on type with error posted, since
647 -- we may have a malformed type that leads us into a loop
651 else
657 -- A class-wide type is never considered to have a known size
662 -- A subtype of a variant record must not have non-static
663 -- discriminanted components.
667 then
670 -- Don't do any recursion on type with error posted, since
671 -- we may have a malformed type that leads us into a loop
677 -- Now look at the components of the record
679 declare
680 -- The following two variables are used to keep track of
681 -- the size of packed records if we can tell the size of
682 -- the packed record in the front end. Packed_Size_Known
683 -- is True if so far we can figure out the size. It is
684 -- initialized to True for a packed record, unless the
685 -- record has discriminants. The reason we eliminate the
686 -- discriminated case is that we don't know the way the
687 -- back end lays out discriminated packed records. If
688 -- Packed_Size_Known is True, then Packed_Size is the
689 -- size in bits so far.
697 begin
698 -- Test for variant part present
704 N_Record_Definition
708 then
709 -- If variant part is present, and type is unconstrained,
710 -- then we must have defaulted discriminants, or a size
711 -- clause must be present for the type, or else the size
712 -- is definitely not known at compile time.
715 and then
716 No (Discriminant_Default_Value
719 then
724 -- Loop through components
729 or else
731 then
734 -- We do not know the packed size if there is a
735 -- component clause present (we possibly could,
736 -- but this would only help in the case of a record
737 -- with partial rep clauses. That's because in the
738 -- case of full rep clauses, the size gets figured
739 -- out anyway by a different circuit).
745 -- We need to identify a component that is an array
746 -- where the index type is an enumeration type with
747 -- non-standard representation, and some bound of the
748 -- type depends on a discriminant.
750 -- This is because gigi computes the size by doing a
751 -- substituation of the appropriate discriminant value
752 -- in the size expression for the base type, and gigi
753 -- is not clever enough to evaluate the resulting
754 -- expression (which involves a call to rep_to_pos)
755 -- at compile time.
757 -- It would be nice if gigi would either recognize that
758 -- this expression can be computed at compile time, or
759 -- alternatively figured out the size from the subtype
760 -- directly, where all the information is at hand ???
764 then
765 declare
773 begin
780 then
785 and then
787 then
791 and then
793 then
803 -- Clearly size of record is not known if the size of
804 -- one of the components is not known.
810 -- Accumulate packed size if possible
814 -- We can only deal with elementary types, since for
815 -- non-elementary components, alignment enters into
816 -- the picture, and we don't know enough to handle
817 -- proper alignment in this context. Packed arrays
818 -- count as elementary if the representation is a
819 -- modular type.
823 and then
825 and then
826 Is_Modular_Integer_Type
828 then
829 -- If RM_Size is known and static, then we can
830 -- keep accumulating the packed size.
834 -- A little glitch, to be removed sometime ???
835 -- gigi does not understand zero sizes yet.
840 -- Normal case where we can keep accumulating
841 -- the packed array size.
843 else
847 -- If we have a field whose RM_Size is not known
848 -- then we can't figure out the packed size here.
850 else
854 -- If we have a non-elementary type we can't figure
855 -- out the packed array size (alignment issues).
857 else
873 else
878 -------------------------------------
879 -- Static_Discriminated_Components --
880 -------------------------------------
882 function Static_Discriminated_Components
884 is
887 begin
891 then
905 -- Start of processing for Check_Compile_Time_Size
907 begin
911 -----------------------------
912 -- Check_Debug_Info_Needed --
913 -----------------------------
916 begin
921 or else Debug_Generated_Code
922 or else Debug_Flag_VV
923 then
928 ----------------------------
929 -- Check_Strict_Alignment --
930 ----------------------------
935 begin
954 then
964 -------------------------
965 -- Check_Unsigned_Type --
966 -------------------------
973 begin
978 -- Do not attempt to analyze case where range was in error
984 -- The situation that is non trivial is something like
986 -- subtype x1 is integer range -10 .. +10;
987 -- subtype x2 is x1 range 0 .. V1;
988 -- subtype x3 is x2 range V2 .. V3;
989 -- subtype x4 is x3 range V4 .. V5;
991 -- where Vn are variables. Here the base type is signed, but we still
992 -- know that x4 is unsigned because of the lower bound of x2.
994 -- The only way to deal with this is to look up the ancestor chain
997 loop
1012 else
1015 -- If no ancestor had a static lower bound, go to base type
1019 -- Note: the reason we still check for a compile time known
1020 -- value for the base type is that at least in the case of
1021 -- generic formals, we can have bounds that fail this test,
1022 -- and there may be other cases in error situations.
1034 then
1044 -----------------------------
1045 -- Expand_Atomic_Aggregate --
1046 -----------------------------
1053 begin
1058 then
1059 Temp :=
1063 New_N :=
1073 -- To prevent the temporary from being constant-folded (which
1074 -- would lead to the same piecemeal assignment on the original
1075 -- target) indicate to the back-end that the temporary is a
1076 -- variable with real storage. See description of this flag
1077 -- in Einfo, and the notes on N_Assignment_Statement and
1078 -- N_Object_Declaration in Sinfo.
1084 ----------------
1085 -- Freeze_All --
1086 ----------------
1088 -- Note: the easy coding for this procedure would be to just build a
1089 -- single list of freeze nodes and then insert them and analyze them
1090 -- all at once. This won't work, because the analysis of earlier freeze
1091 -- nodes may recursively freeze types which would otherwise appear later
1092 -- on in the freeze list. So we must analyze and expand the freeze nodes
1093 -- as they are generated.
1101 -- This is the internal recursive routine that does freezing of
1102 -- entities (but NOT the analysis of default expressions, which
1103 -- should not be recursive, we don't want to analyze those till
1104 -- we are sure that ALL the types are frozen).
1106 --------------------
1107 -- Freeze_All_Ent --
1108 --------------------
1110 procedure Freeze_All_Ent
1113 is
1119 -- If freeze nodes are present, insert and analyze, and reset
1120 -- cursor for next insertion.
1122 -------------------
1123 -- Process_Flist --
1124 -------------------
1127 begin
1134 else
1140 -- Start or processing for Freeze_All_Ent
1142 begin
1146 -- If the entity is an inner package which is not a package
1147 -- renaming, then its entities must be frozen at this point.
1148 -- Note that such entities do NOT get frozen at the end of
1149 -- the nested package itself (only library packages freeze).
1151 -- Same is true for task declarations, where anonymous records
1152 -- created for entry parameters must be frozen.
1158 then
1168 and then
1170 or else
1172 then
1175 End_Scope;
1177 -- For a derived tagged type, we must ensure that all the
1178 -- primitive operations of the parent have been frozen, so
1179 -- that their addresses will be in the parent's dispatch table
1180 -- at the point it is inherited.
1186 then
1187 declare
1194 begin
1202 then
1204 Process_Flist;
1214 Process_Flist;
1217 -- If an incomplete type is still not frozen, this may be
1218 -- a premature freezing because of a body declaration that
1219 -- follows. Indicate where the freezing took place.
1221 -- If the freezing is caused by the end of the current
1222 -- declarative part, it is a Taft Amendment type, and there
1223 -- is no error.
1227 then
1228 declare
1231 begin
1238 and then
1240 then
1242 Error_Msg_NE
1253 -- Start of processing for Freeze_All
1255 begin
1258 -- Now that all types are frozen, we can deal with default expressions
1259 -- that require us to build a default expression functions. This is the
1260 -- point at which such functions are constructed (after all types that
1261 -- might be used in such expressions have been frozen).
1263 -- We also add finalization chains to access types whose designated
1264 -- types are controlled. This is normally done when freezing the type,
1265 -- but this misses recursive type definitions where the later members
1266 -- of the recursion introduce controlled components (e.g. 5624-001).
1268 -- Loop through entities
1286 and then
1288 = N_Subprogram_Renaming_Declaration
1289 then
1290 Build_And_Analyze_Renamed_Body
1296 and then
1298 or else
1300 then
1301 declare
1303 begin
1310 then
1323 then
1331 -----------------------
1332 -- Freeze_And_Append --
1333 -----------------------
1335 procedure Freeze_And_Append
1339 is
1341 begin
1345 else
1351 -------------------
1352 -- Freeze_Before --
1353 -------------------
1357 begin
1363 -------------------
1364 -- Freeze_Entity --
1365 -------------------
1376 -- Check that an Access or Unchecked_Access attribute with
1377 -- a prefix which is the current instance type can only be
1378 -- applied when the type is limited.
1381 -- If Loc is a freeze_entity that appears after the last declaration
1382 -- in the scope, inhibit error messages on late completion.
1385 -- Freeze each component, handle some representation clauses, and
1386 -- freeze primitive operations if this is a tagged type.
1388 ----------------------------
1389 -- After_Last_Declaration --
1390 ----------------------------
1395 begin
1402 else
1406 else
1411 ----------------------------
1412 -- Check_Current_Instance --
1413 ----------------------------
1418 -- Process routine to apply check to given node.
1420 -------------
1421 -- Process --
1422 -------------
1425 begin
1429 or else
1434 then
1435 Error_Msg_N
1438 else
1448 -- Start of processing for Check_Current_Instance
1450 begin
1454 ------------------------
1455 -- Freeze_Record_Type --
1456 ------------------------
1465 -- Set True if we find at least one component with no component
1466 -- clause (used to warn about useless Pack pragmas).
1469 -- Set True if we find at least one component with a component
1470 -- clause (used to warn about useless Bit_Order pragmas).
1473 -- If the component subtype is an access to a constrained subtype
1474 -- of an already frozen type, make the subtype frozen as well. It
1475 -- might otherwise be frozen in the wrong scope, and a freeze node
1476 -- on subtype has no effect.
1478 -----------------
1479 -- Check_Itype --
1480 -----------------
1483 begin
1486 then
1489 -- In addition, add an Itype_Reference to ensure that the
1490 -- access subtype is elaborated early enough. This cannot
1491 -- be done if the subtype may depend on discriminants.
1496 then
1502 else
1509 -- Start of processing for Freeze_Record_Type
1511 begin
1512 -- If this is a subtype of a controlled type, declared without
1513 -- a constraint, the _controller may not appear in the component
1514 -- list if the parent was not frozen at the point of subtype
1515 -- declaration. Inherit the _controller component now.
1519 then
1522 then
1525 -- If this is an internal type without a declaration, as for a
1526 -- record component, the base type may not yet be frozen, and its
1527 -- controller has not been created. Add an explicit freeze node
1528 -- for the itype, so it will be frozen after the base type.
1532 and then
1534 N_Component_Declaration
1535 then
1540 -- Freeze components and embedded subtypes
1548 -- If the component is an access type with an allocator
1549 -- as default value, the designated type will be frozen
1550 -- by the corresponding expression in init_proc. In order
1551 -- to place the freeze node for the designated type before
1552 -- that for the current record type, freeze it now.
1554 -- Same process if the component is an array of access types,
1555 -- initialized with an aggregate. If the designated type is
1556 -- private, it cannot contain allocators, and it is premature
1557 -- to freeze the type, so we check for this as well.
1563 then
1564 declare
1567 begin
1568 -- If component is pointer to a classwide type, freeze
1569 -- the specific type in the expression being allocated.
1570 -- The expression may be a subtype indication, in which
1571 -- case freeze the subtype mark.
1575 Freeze_And_Append
1577 elsif
1579 then
1580 Freeze_And_Append
1588 else
1589 Freeze_And_Append
1596 then
1605 and then Is_Fully_Defined
1607 then
1608 Freeze_And_Append
1609 (Designated_Type
1613 -- Processing for real components (exclude anonymous subtypes)
1617 then
1618 declare
1621 begin
1622 -- Check for error of component clause given for variable
1623 -- sized type. We have to delay this test till this point,
1624 -- since the component type has to be frozen for us to know
1625 -- if it is variable length. We omit this test in a generic
1626 -- context, it will be applied at instantiation time.
1634 elsif not Size_Known_At_Compile_Time
1636 then
1637 Error_Msg_N
1642 else
1646 -- Case of component requires byte alignment
1650 -- Set the enclosing record to also require byte align
1654 -- Check for component clause that is inconsistent
1655 -- with the required byte boundary alignment.
1660 then
1661 Error_Msg_N
1667 -- If component clause is present, then deal with the
1668 -- non-default bit order case. We cannot do this before
1669 -- the freeze point, because there is no required order
1670 -- for the component clause and the bit_order clause.
1672 -- We only do this processing for the base type, and in
1673 -- fact that's important, since otherwise if there are
1674 -- record subtypes, we could reverse the bits once for
1675 -- each subtype, which would be incorrect.
1680 then
1681 declare
1694 begin
1695 -- Cases where field goes over storage unit boundary
1699 -- Allow multi-byte field but generate warning
1703 then
1704 Error_Msg_N
1709 Error_Msg_N
1712 else
1713 Error_Msg_N
1718 -- Do not allow non-contiguous field
1720 else
1721 Error_Msg_N
1724 Error_Msg_N
1729 -- Case where field fits in one storage unit
1731 else
1732 -- Give warning if suspicious component clause
1735 Error_Msg_N
1738 Error_Msg_Uint_1 :=
1740 System_Storage_Unit;
1741 Error_Msg_N
1746 -- Here is where we fix up the Component_Bit_Offset
1747 -- value to account for the reverse bit order.
1748 -- Some examples of what needs to be done are:
1750 -- First_Bit .. Last_Bit Component_Bit_Offset
1751 -- old new old new
1753 -- 0 .. 0 7 .. 7 0 7
1754 -- 0 .. 1 6 .. 7 0 6
1755 -- 0 .. 2 5 .. 7 0 5
1756 -- 0 .. 7 0 .. 7 0 4
1758 -- 1 .. 1 6 .. 6 1 6
1759 -- 1 .. 4 3 .. 6 1 3
1760 -- 4 .. 7 0 .. 3 4 0
1762 -- The general rule is that the first bit is
1763 -- is obtained by subtracting the old ending bit
1764 -- from storage_unit - 1.
1766 Set_Component_Bit_Offset
1772 Set_Normalized_First_Bit
1775 System_Storage_Unit);
1785 -- Check for useless pragma Bit_Order
1793 -- Check for useless pragma Pack when all components placed
1796 and then not Unplaced_Component
1797 and then Warn_On_Redundant_Constructs
1798 then
1799 Error_Msg_N
1805 -- If this is the record corresponding to a remote type,
1806 -- freeze the remote type here since that is what we are
1807 -- semantically freezing. This prevents having the freeze
1808 -- node for that type in an inner scope.
1810 -- Also, Check for controlled components and unchecked unions.
1811 -- Finally, enforce the restriction that access attributes with
1812 -- a current instance prefix can only apply to limited types.
1816 Freeze_And_Append
1826 and then Present
1828 and then Has_Controlled_Component
1830 then
1841 then
1842 -- Scan component declaration for likely misuses of
1843 -- current instance, either in a constraint or in a
1844 -- default expression.
1855 -- For first subtypes, check if there are any fixed-point
1856 -- fields with component clauses, where we must check the size.
1857 -- This is not done till the freeze point, since for fixed-point
1858 -- types, we do not know the size until the type is frozen.
1859 -- Similar processing applies to bit packed arrays.
1867 or else
1869 then
1870 Check_Size
1874 Junk);
1882 -- Start of processing for Freeze_Entity
1884 begin
1885 -- Do not freeze if already frozen since we only need one freeze node
1890 -- It is improper to freeze an external entity within a generic
1891 -- because its freeze node will appear in a non-valid context.
1892 -- The entity will be frozen in the proper scope after the current
1893 -- generic is analyzed.
1898 -- Do not freeze a global entity within an inner scope created during
1899 -- expansion. A call to subprogram E within some internal procedure
1900 -- (a stream attribute for example) might require freezing E, but the
1901 -- freeze node must appear in the same declarative part as E itself.
1902 -- The two-pass elaboration mechanism in gigi guarantees that E will
1903 -- be frozen before the inner call is elaborated. We exclude constants
1904 -- from this test, because deferred constants may be frozen early, and
1905 -- must be diagnosed (see e.g. 1522-005). If the enclosing subprogram
1906 -- comes from source, or is a generic instance, then the freeze point
1907 -- is the one mandated by the language. and we freze the entity.
1912 then
1913 declare
1916 begin
1921 then
1923 else
1932 -- Similarly, an inlined instance body may make reference to global
1933 -- entities, but these references cannot be the proper freezing point
1934 -- for them, and the the absence of inlining freezing will take place
1935 -- in their own scope. Normally instance bodies are analyzed after
1936 -- the enclosing compilation, and everything has been frozen at the
1937 -- proper place, but with front-end inlining an instance body is
1938 -- compiled before the end of the enclosing scope, and as a result
1939 -- out-of-order freezing must be prevented.
1941 elsif Front_End_Inlining
1942 and then In_Instance_Body
1944 then
1945 declare
1947 begin
1951 else
1962 -- Here to freeze the entity
1967 -- Case of entity being frozen is other than a type
1971 -- If entity is exported or imported and does not have an external
1972 -- name, now is the time to provide the appropriate default name.
1973 -- Skip this if the entity is stubbed, since we don't need a name
1974 -- for any stubbed routine.
1979 then
1980 Set_Encoded_Interface_Name
1983 -- Special processing for atomic objects appearing in object decls
1988 then
1989 declare
1992 begin
1993 -- If expression is an aggregate, assign to a temporary to
1994 -- ensure that the actual assignment is done atomically rather
1995 -- than component-wise (the assignment to the temp may be done
1996 -- component-wise, but that is harmless.
2001 -- If the expression is a reference to a record or array
2002 -- object entity, then reset Is_True_Constant to False so
2003 -- that the compiler will not optimize away the intermediate
2004 -- object, which we need in this case for the same reason
2005 -- (to ensure that the actual assignment is atomic, rather
2006 -- than component-wise).
2010 or else
2012 then
2018 -- For a subprogram, freeze all parameter types and also the return
2019 -- type (RM 13.14(14)). However skip this for internal subprograms.
2020 -- This is also the point where any extra formal parameters are
2021 -- created since we now know whether the subprogram will use
2022 -- a foreign convention.
2026 declare
2031 -- Determines if given type entity is a fat pointer type
2032 -- used as an argument type or return type to a subprogram
2033 -- with C or C++ convention set.
2035 --------------------------
2036 -- Is_Fat_C_Access_Type --
2037 --------------------------
2040 begin
2042 or else
2048 begin
2049 -- Loop through formals
2061 then
2062 -- If the type of a formal is incomplete, subprogram
2063 -- is being frozen prematurely. Within an instance
2064 -- (but not within a wrapper package) this is an
2065 -- an artifact of our need to regard the end of an
2066 -- instantiation as a freeze point. Otherwise it is
2067 -- a definite error.
2069 -- and then not Is_Wrapper_Package (Current_Scope) ???
2077 Error_Msg
2079 Loc);
2083 -- Check bad use of fat C pointer
2087 then
2089 Error_Msg_N
2091 Formal);
2095 -- Check for unconstrained array in exported foreign
2096 -- convention case.
2102 and then Warn_On_Export_Import
2103 then
2106 -- If this is an inherited operation, place the
2107 -- warning on the derived type declaration, rather
2108 -- than on the original subprogram.
2111 N_Full_Type_Declaration
2112 then
2116 Error_Msg_NE
2119 else
2123 Error_Msg_NE
2126 Error_Msg_NE
2135 -- Check return type
2140 if Warn_On_Export_Import
2142 then
2143 Error_Msg_N
2145 E);
2151 and then Warn_On_Export_Import
2152 then
2153 Error_Msg_N
2161 -- Must freeze its parent first if it is a derived subprogram
2167 -- If the return type requires a transient scope, and we are on
2168 -- a target allowing functions to return with a depressed stack
2169 -- pointer, then we mark the function as requiring this treatment.
2172 and then Functions_Return_By_DSP_On_Target
2174 then
2182 -- Here for other than a subprogram or type
2184 else
2185 -- If entity has a type, and it is not a generic unit, then
2186 -- freeze it first (RM 13.14(10))
2190 then
2194 -- Special processing for objects created by object declaration
2198 -- For object created by object declaration, perform required
2199 -- categorization (preelaborate and pure) checks. Defer these
2200 -- checks to freeze time since pragma Import inhibits default
2201 -- initialization and thus pragma Import affects these checks.
2205 -- If there is an address clause, check it is valid
2209 -- For imported objects, set Is_Public unless there is also
2210 -- an address clause, which means that there is no external
2211 -- symbol needed for the Import (Is_Public may still be set
2212 -- for other unrelated reasons). Note that we delayed this
2213 -- processing till freeze time so that we can be sure not
2214 -- to set the flag if there is an address clause. If there
2215 -- is such a clause, then the only purpose of the import
2216 -- pragma is to suppress implicit initialization.
2220 then
2225 -- Check that a constant which has a pragma Volatile[_Components]
2226 -- or Atomic[_Components] also has a pragma Import (RM C.6(13))
2228 -- Note: Atomic[_Components] also sets Volatile[_Components]
2233 then
2234 -- Make sure we actually have a pragma, and have not merely
2235 -- inherited the indication from elsewhere (e.g. an address
2236 -- clause, which is not good enough in RM terms!)
2239 or else
2241 then
2242 Error_Msg_N
2247 or else
2249 then
2250 Error_Msg_N
2256 -- Static objects require special handling
2260 then
2264 -- Remaining step is to layout objects
2267 or else
2269 or else
2271 or else
2273 then
2278 -- Case of a type or subtype being frozen
2280 else
2281 -- The type may be defined in a generic unit. This can occur when
2282 -- freezing a generic function that returns the type (which is
2283 -- defined in a parent unit). It is clearly meaningless to freeze
2284 -- this type. However, if it is a subtype, its size may be determi-
2285 -- nable and used in subsequent checks, so might as well try to
2286 -- compute it.
2290 then
2295 -- Deal with special cases of freezing for subtype
2299 -- If ancestor subtype present, freeze that first.
2300 -- Note that this will also get the base type frozen.
2307 -- Otherwise freeze the base type of the entity before
2308 -- freezing the entity itself, (RM 13.14(15)).
2314 -- For a derived type, freeze its parent type first (RM 13.14(15))
2321 -- For array type, freeze index types and component type first
2322 -- before freezing the array (RM 13.14(15)).
2325 declare
2330 -- Set true if any of the index types is an enumeration
2331 -- type with a non-standard representation.
2333 begin
2342 then
2349 -- Processing that is done only for base types
2353 -- Propagate flags for component type
2357 then
2365 -- If packing was requested or if the component size was set
2366 -- explicitly, then see if bit packing is required. This
2367 -- processing is only done for base types, since all the
2368 -- representation aspects involved are type-related. This
2369 -- is not just an optimization, if we start processing the
2370 -- subtypes, they intefere with the settings on the base
2371 -- type (this is because Is_Packed has a slightly different
2372 -- meaning before and after freezing).
2374 declare
2378 begin
2382 then
2391 else
2394 -- We can set the component size if it is less than
2395 -- 16, rounding it up to the next storage unit size.
2401 else
2405 -- Set component size up to match alignment if
2406 -- it would otherwise be less than the alignment.
2407 -- This deals with cases of types whose alignment
2408 -- exceeds their sizes (padded types).
2411 declare
2414 begin
2425 -- We set the component size for all cases 1-64
2429 -- Check for base type of 8,16,32 bits, where the
2430 -- subtype has a length one less than the base type
2431 -- and is unsigned (e.g. Natural subtype of Integer)
2433 -- In such cases, if a component size was not set
2434 -- explicitly, then generate a warning.
2438 and then
2441 then
2443 Pnod :=
2447 Error_Msg_N
2449 Pnod);
2450 Error_Msg_N
2452 Pnod);
2456 -- Actual packing is not needed for 8,16,32,64
2457 -- Also not needed for 24 if alignment is 1
2464 then
2465 -- Here the array was requested to be packed, but
2466 -- the packing request had no effect, so Is_Packed
2467 -- is reset.
2469 -- Note: semantically this means that we lose
2470 -- track of the fact that a derived type inherited
2471 -- a pack pragma that was non-effective, but that
2472 -- seems fine.
2474 -- We regard a Pack pragma as a request to set a
2475 -- representation characteristic, and this request
2476 -- may be ignored.
2480 -- In all other cases, packing is indeed needed
2482 else
2490 -- Processing that is done only for subtypes
2492 else
2493 -- Acquire alignment from base type
2500 -- For bit-packed arrays, check the size
2504 then
2505 declare
2509 begin
2510 -- It is not clear if it is possible to have no size
2511 -- clause at this stage, but this is not worth worrying
2512 -- about. Post the error on the entity name in the size
2513 -- clause if present, else on the type entity itself.
2517 else
2523 -- Check one common case of a size given where the array
2524 -- needs to be packed, but was not so the size cannot be
2525 -- honored. This would of course be caught by the backend,
2526 -- and indeed we don't catch all cases. The point is that
2527 -- we can give a better error message in those cases that
2528 -- we do catch with the circuitry here.
2530 declare
2534 begin
2542 then
2549 then
2550 declare
2557 -- What we are looking for here is the situation
2558 -- where the Esize given would be exactly right
2559 -- if there was a pragma Pack (resulting in the
2560 -- component size being the same as the RM_Size).
2561 -- Furthermore, the component type size must be
2562 -- an odd size (not a multiple of storage unit)
2564 begin
2567 then
2568 Error_Msg_NE
2571 Error_Msg_N
2580 -- If any of the index types was an enumeration type with
2581 -- a non-standard rep clause, then we indicate that the
2582 -- array type is always packed (even if it is not bit packed).
2591 -- If the array is packed, we must create the packed array
2592 -- type to be used to actually implement the type. This is
2593 -- only needed for real array types (not for string literal
2594 -- types, since they are present only for the front end).
2598 then
2602 -- Size information of packed array type is copied to the
2603 -- array type, since this is really the representation.
2609 -- For non-packed arrays set the alignment of the array
2610 -- to the alignment of the component type if it is unknown.
2611 -- Skip this in the atomic case, since atomic arrays may
2612 -- need larger alignments.
2621 then
2626 -- For a class-wide type, the corresponding specific type is
2627 -- frozen as well (RM 13.14(15))
2632 -- If the Class_Wide_Type is an Itype (when type is the anonymous
2633 -- parent of a derived type) and it is a library-level entity,
2634 -- generate an itype reference for it. Otherwise, its first
2635 -- explicit reference may be in an inner scope, which will be
2636 -- rejected by the back-end.
2640 then
2641 declare
2644 begin
2648 else
2654 -- The equivalent type associated with a class-wide subtype
2655 -- needs to be frozen to ensure that its layout is done.
2656 -- Class-wide subtypes are currently only frozen on targets
2657 -- requiring front-end layout (see New_Class_Wide_Subtype
2658 -- and Make_CW_Equivalent_Type in exp_util.adb).
2662 then
2666 -- For a record (sub)type, freeze all the component types (RM
2667 -- 13.14(15). We test for E_Record_(sub)Type here, rather than
2668 -- using Is_Record_Type, because we don't want to attempt the
2669 -- freeze for the case of a private type with record extension
2670 -- (we will do that later when the full type is frozen).
2674 then
2677 -- For a concurrent type, freeze corresponding record type. This
2678 -- does not correpond to any specific rule in the RM, but the
2679 -- record type is essentially part of the concurrent type.
2680 -- Freeze as well all local entities. This includes record types
2681 -- created for entry parameter blocks, and whatever local entities
2682 -- may appear in the private part.
2686 Freeze_And_Append
2703 -- Private types are required to point to the same freeze node
2704 -- as their corresponding full views. The freeze node itself
2705 -- has to point to the partial view of the entity (because
2706 -- from the partial view, we can retrieve the full view, but
2707 -- not the reverse). However, in order to freeze correctly,
2708 -- we need to freeze the full view. If we are freezing at the
2709 -- end of a scope (or within the scope of the private type),
2710 -- the partial and full views will have been swapped, the
2711 -- full view appears first in the entity chain and the swapping
2712 -- mechanism ensures that the pointers are properly set (on
2713 -- scope exit).
2715 -- If we encounter the partial view before the full view
2716 -- (e.g. when freezing from another scope), we freeze the
2717 -- full view, and then set the pointers appropriately since
2718 -- we cannot rely on swapping to fix things up (subtypes in an
2719 -- outer scope might not get swapped).
2723 then
2724 -- Case of full view present
2728 -- If full view has already been frozen, then no
2729 -- further processing is required
2737 -- Otherwise freeze full view and patch the pointers
2738 -- so that the freeze node will elaborate both views
2739 -- in the back-end.
2741 else
2742 declare
2745 begin
2748 then
2749 Freeze_And_Append
2762 else
2763 -- {Incomplete,Private}_Subtypes
2764 -- with Full_Views constrained by discriminants
2775 -- AI-117 requires that the convention of a partial view
2776 -- be the same as the convention of the full view. Note
2777 -- that this is a recognized breach of privacy, but it's
2778 -- essential for logical consistency of representation,
2779 -- and the lack of a rule in RM95 was an oversight.
2786 -- Size information is copied from the full view to the
2787 -- incomplete or private view for consistency
2789 -- We skip this is the full view is not a type. This is
2790 -- very strange of course, and can only happen as a result
2791 -- of certain illegalities, such as a premature attempt to
2792 -- derive from an incomplete type.
2801 -- Case of no full view present. If entity is derived or subtype,
2802 -- it is safe to freeze, correctness depends on the frozen status
2803 -- of parent. Otherwise it is either premature usage, or a Taft
2804 -- amendment type, so diagnosis is at the point of use and the
2805 -- type might be frozen later.
2809 then
2812 else
2817 -- For access subprogram, freeze types of all formals, the return
2818 -- type was already frozen, since it is the Etype of the function.
2827 -- If the return type requires a transient scope, and we are on
2828 -- a target allowing functions to return with a depressed stack
2829 -- pointer, then we mark the function as requiring this treatment.
2831 if Functions_Return_By_DSP_On_Target
2833 then
2839 -- For access to a protected subprogram, freeze the equivalent
2840 -- type (however this is not set if we are not generating code)
2841 -- or if this is an anonymous type used just for resolution).
2846 then
2850 -- Generic types are never seen by the back-end, and are also not
2851 -- processed by the expander (since the expander is turned off for
2852 -- generic processing), so we never need freeze nodes for them.
2858 -- Some special processing for non-generic types to complete
2859 -- representation details not known till the freeze point.
2864 -- Some error checks required for ordinary fixed-point type.
2865 -- Defer these till the freeze-point since we need the small
2866 -- and range values. We only do these checks for base types
2870 then
2873 Error_Msg_N
2878 Error_Msg_N
2884 Error_Msg_N
2890 Error_Msg_N
2903 then
2907 -- If the current entity is an array or record subtype and has
2908 -- discriminants used to constrain it, it must not freeze, because
2909 -- Freeze_Entity nodes force Gigi to process the frozen type.
2914 declare
2919 begin
2927 then
2944 then
2945 declare
2949 begin
2955 then
2967 -- AI-117 requires that all new primitives of a tagged type
2968 -- must inherit the convention of the full view of the type.
2969 -- Inherited and overriding operations are defined to inherit
2970 -- the convention of their parent or overridden subprogram
2971 -- (also specified in AI-117), and that will have occurred
2972 -- earlier (in Derive_Subprogram and New_Overloaded_Entity).
2973 -- Here we set the convention of primitives that are still
2974 -- convention Ada, which will ensure that any new primitives
2975 -- inherit the type's convention. Class-wide types can have
2976 -- a foreign convention inherited from their specific type,
2977 -- but are excluded from this since they don't have any
2978 -- associated primitives.
2983 then
2984 declare
2987 begin
3000 -- Generate primitive operation references for a tagged type
3004 then
3005 declare
3010 begin
3015 -- If the operation is derived, get the original for
3016 -- cross-reference purposes (it is the original for
3017 -- which we want the xref, and for which the comes
3018 -- from source test needs to be performed).
3028 -- If we get an exception, then something peculiar has happened
3029 -- probably as a result of a previous error. Since this is only
3030 -- for non-critical cross-references, ignore the error.
3032 exception
3037 -- Now that all types from which E may depend are frozen, see
3038 -- if the size is known at compile time, if it must be unsigned,
3039 -- or if strict alignent is required
3048 -- Do not allow a size clause for a type which does not have a size
3049 -- that is known at compile time
3053 then
3054 -- Supress this message if errors posted on E, even if we are
3055 -- in all errors mode, since this is often a junk message
3058 Error_Msg_N
3064 -- Remaining process is to set/verify the representation information,
3065 -- in particular the size and alignment values. This processing is
3066 -- not required for generic types, since generic types do not play
3067 -- any part in code generation, and so the size and alignment values
3068 -- for suhc types are irrelevant.
3073 -- Otherwise we call the layout procedure
3075 else
3079 -- End of freeze processing for type entities
3082 -- Here is where we logically freeze the current entity. If it has a
3083 -- freeze node, then this is the point at which the freeze node is
3084 -- linked into the result list.
3088 -- If a freeze node is already allocated, use it, otherwise allocate
3089 -- a new one. The preallocation happens in the case of anonymous base
3090 -- types, where we preallocate so that we can set First_Subtype_Link.
3091 -- Note that we reset the Sloc to the current freeze location.
3097 else
3109 else
3113 -- A final pass over record types with discriminants. If the type
3114 -- has an incomplete declaration, there may be constrained access
3115 -- subtypes declared elsewhere, which do not depend on the discrimi-
3116 -- nants of the type, and which are used as component types (i.e.
3117 -- the full view is a recursive type). The designated types of these
3118 -- subtypes can only be elaborated after the type itself, and they
3119 -- need an itype reference.
3123 then
3124 declare
3129 begin
3140 then
3152 -- When a type is frozen, the first subtype of the type is frozen as
3153 -- well (RM 13.14(15)). This has to be done after freezing the type,
3154 -- since obviously the first subtype depends on its own base type.
3159 -- If we just froze a tagged non-class wide record, then freeze the
3160 -- corresponding class-wide type. This must be done after the tagged
3161 -- type itself is frozen, because the class-wide type refers to the
3162 -- tagged type which generates the class.
3167 then
3174 -- Special handling for subprograms
3178 -- If subprogram has address clause then reset Is_Public flag, since
3179 -- we do not want the backend to generate external references.
3183 then
3186 -- If no address clause and not intrinsic, then for imported
3187 -- subprogram in main unit, generate descriptor if we are in
3188 -- Propagate_Exceptions mode.
3190 elsif Propagate_Exceptions
3194 then
3199 Generate_Subprogram_Descriptor_For_Imported_Subprogram
3207 -----------------------------
3208 -- Freeze_Enumeration_Type --
3209 -----------------------------
3212 begin
3216 then
3218 else
3223 -----------------------
3224 -- Freeze_Expression --
3225 -----------------------
3236 -- This flag is set true if the entity must be frozen outside the
3237 -- current subprogram. This happens in the case of expander generated
3238 -- subprograms (_Init_Proc, _Input, _Output, _Read, _Write) which do
3239 -- not freeze all entities like other bodies, but which nevertheless
3240 -- may reference entities that have to be frozen before the body and
3241 -- obviously cannot be frozen inside the body.
3244 -- Given an N_Handled_Sequence_Of_Statements node N, determines whether
3245 -- it is the handled statement sequence of an expander generated
3246 -- subprogram (init proc, or stream subprogram). If so, it returns
3247 -- True, otherwise False.
3249 -----------------
3250 -- In_Exp_Body --
3251 -----------------
3256 begin
3259 else
3266 else
3275 then
3277 else
3283 -- Start of processing for Freeze_Expression
3285 begin
3286 -- Immediate return if freezing is inhibited. This flag is set by
3287 -- the analyzer to stop freezing on generated expressions that would
3288 -- cause freezing if they were in the source program, but which are
3289 -- not supposed to freeze, since they are created.
3295 -- If expression is non-static, then it does not freeze in a default
3296 -- expression, see section "Handling of Default Expressions" in the
3297 -- spec of package Sem for further details. Note that we have to
3298 -- make sure that we actually have a real expression (if we have
3299 -- a subtype indication, we can't test Is_Static_Expression!)
3301 if In_Def_Exp
3304 then
3308 -- Freeze type of expression if not frozen already
3316 -- Base type may be an derived numeric type that is frozen at
3317 -- the point of declaration, but first_subtype is still unfrozen.
3324 -- For entity name, freeze entity if not frozen already. A special
3325 -- exception occurs for an identifier that did not come from source.
3326 -- We don't let such identifiers freeze a non-internal entity, i.e.
3327 -- an entity that did come from source, since such an identifier was
3328 -- generated by the expander, and cannot have any semantic effect on
3329 -- the freezing semantics. For example, this stops the parameter of
3330 -- an initialization procedure from freezing the variable.
3337 then
3339 else
3343 -- For an allocator freeze designated type if not frozen already.
3345 -- For an aggregate whose component type is an access type, freeze
3346 -- the designated type now, so that its freeze does not appear within
3347 -- the loop that might be created in the expansion of the aggregate.
3348 -- If the designated type is a private type without full view, the
3349 -- expression cannot contain an allocator, so the type is not frozen.
3360 then
3364 when N_Selected_Component |
3365 N_Indexed_Component |
3366 N_Slice =>
3379 then
3383 -- All done if nothing needs freezing
3388 then
3392 -- Loop for looking at the right place to insert the freeze nodes
3393 -- exiting from the loop when it is appropriate to insert the freeze
3394 -- node before the current node P.
3396 -- Also checks some special exceptions to the freezing rules. These
3397 -- cases result in a direct return, bypassing the freeze action.
3400 loop
3403 -- If we don't have a parent, then we are not in a well-formed
3404 -- tree. This is an unusual case, but there are some legitimate
3405 -- situations in which this occurs, notably when the expressions
3406 -- in the range of a type declaration are resolved. We simply
3407 -- ignore the freeze request in this case. Is this right ???
3413 -- See if we have got to an appropriate point in the tree
3417 -- A special test for the exception of (RM 13.14(8)) for the
3418 -- case of per-object expressions (RM 3.8(18)) occurring in a
3419 -- component definition or a discrete subtype definition. Note
3420 -- that we test for a component declaration which includes both
3421 -- cases we are interested in, and furthermore the tree does not
3422 -- have explicit nodes for either of these two constructs.
3426 -- The case we want to test for here is an identifier that is
3427 -- a per-object expression, this is either a discriminant that
3428 -- appears in a context other than the component declaration
3429 -- or it is a reference to the type of the enclosing construct.
3431 -- For either of these cases, we skip the freezing
3433 if not In_Default_Expression
3436 then
3437 -- We recognize the discriminant case by just looking for
3438 -- a reference to a discriminant. It can only be one for
3439 -- the enclosing construct. Skip freezing in this case.
3444 -- For the case of a reference to the enclosing record,
3445 -- (or task or protected type), we look for a type that
3446 -- matches the current scope.
3453 -- If we have an enumeration literal that appears as the
3454 -- choice in the aggregate of an enumeration representation
3455 -- clause, then freezing does not occur (RM 13.14(10)).
3459 -- The case we are looking for is an enumeration literal
3463 then
3464 -- If enumeration literal appears directly as the choice,
3465 -- do not freeze (this is the normal non-overloade case)
3469 then
3472 -- If enumeration literal appears as the name of a
3473 -- function which is the choice, then also do not freeze.
3474 -- This happens in the overloaded literal case, where the
3475 -- enumeration literal is temporarily changed to a function
3476 -- call for overloading analysis purposes.
3479 and then
3481 and then
3483 then
3488 -- Normally if the parent is a handled sequence of statements,
3489 -- then the current node must be a statement, and that is an
3490 -- appropriate place to insert a freeze node.
3494 -- An exception occurs when the sequence of statements is
3495 -- for an expander generated body that did not do the usual
3496 -- freeze all operation. In this case we usually want to
3497 -- freeze outside this body, not inside it, and we skip
3498 -- past the subprogram body that we are inside.
3502 -- However, we *do* want to freeze at this point if we have
3503 -- an entity to freeze, and that entity is declared *inside*
3504 -- the body of the expander generated procedure. This case
3505 -- is recognized by the scope of the type, which is either
3506 -- the spec for some enclosing body, or (in the case of
3507 -- init_procs, for which there are no separate specs) the
3508 -- current scope.
3510 declare
3514 begin
3519 or else
3521 then
3527 then
3533 -- If not that exception to the exception, then this is
3534 -- where we delay the freeze till outside the body.
3539 -- Here if normal case where we are in handled statement
3540 -- sequence and want to do the insertion right there.
3542 else
3546 -- If parent is a body or a spec or a block, then the current
3547 -- node is a statement or declaration and we can insert the
3548 -- freeze node before it.
3550 when N_Package_Specification |
3551 N_Package_Body |
3552 N_Subprogram_Body |
3553 N_Task_Body |
3554 N_Protected_Body |
3555 N_Entry_Body |
3558 -- The expander is allowed to define types in any statements list,
3559 -- so any of the following parent nodes also mark a freezing point
3560 -- if the actual node is in a list of statements or declarations.
3562 when N_Exception_Handler |
3563 N_If_Statement |
3564 N_Elsif_Part |
3565 N_Case_Statement_Alternative |
3566 N_Compilation_Unit_Aux |
3567 N_Selective_Accept |
3568 N_Accept_Alternative |
3569 N_Delay_Alternative |
3570 N_Conditional_Entry_Call |
3571 N_Entry_Call_Alternative |
3572 N_Triggering_Alternative |
3573 N_Abortable_Part |
3574 N_Freeze_Entity =>
3578 -- Note: The N_Loop_Statement is a special case. A type that
3579 -- appears in the source can never be frozen in a loop (this
3580 -- occurs only because of a loop expanded by the expander),
3581 -- so we keep on going. Otherwise we terminate the search.
3582 -- Same is true of any entity which comes from source. (if they
3583 -- have a predefined type, that type does not appear to come
3584 -- from source, but the entity should not be frozen here).
3590 -- For all other cases, keep looking at parents
3596 -- We fall through the case if we did not yet find the proper
3597 -- place in the free for inserting the freeze node, so climb!
3602 -- If the expression appears in a record or an initialization
3603 -- procedure, the freeze nodes are collected and attached to
3604 -- the current scope, to be inserted and analyzed on exit from
3605 -- the scope, to insure that generated entities appear in the
3606 -- correct scope. If the expression is a default for a discriminant
3607 -- specification, the scope is still void. The expression can also
3608 -- appear in the discriminant part of a private or concurrent type.
3610 -- The other case requiring this special handling is if we are in
3611 -- a default expression, since in that case we are about to freeze
3612 -- a static type, and the freeze scope needs to be the outer scope,
3613 -- not the scope of the subprogram with the default parameter.
3615 -- For default expressions in generic units, the Move_Freeze_Nodes
3616 -- mechanism (see sem_ch12.adb) takes care of placing them at the
3617 -- proper place, after the generic unit.
3620 or else Freeze_Outside
3625 then
3626 declare
3630 begin
3646 then
3647 Scope_Stack.Table
3649 Freeze_Nodes;
3650 else
3660 -- Now we have the right place to do the freezing. First, a special
3661 -- adjustment, if we are in default expression analysis mode, these
3662 -- freeze actions must not be thrown away (normally all inserted
3663 -- actions are thrown away in this mode. However, the freeze actions
3664 -- are from static expressions and one of the important reasons we
3665 -- are doing this special analysis is to get these freeze actions.
3666 -- Therefore we turn off the In_Default_Expression mode to propagate
3667 -- these freeze actions. This also means they get properly analyzed
3668 -- and expanded.
3672 -- Freeze the designated type of an allocator (RM 13.14(13))
3678 -- Freeze type of expression (RM 13.14(10)). Note that we took care of
3679 -- the enumeration representation clause exception in the loop above.
3685 -- Freeze name if one is present (RM 13.14(11))
3694 -----------------------------
3695 -- Freeze_Fixed_Point_Type --
3696 -----------------------------
3698 -- Certain fixed-point types and subtypes, including implicit base
3699 -- types and declared first subtypes, have not yet set up a range.
3700 -- This is because the range cannot be set until the Small and Size
3701 -- values are known, and these are not known till the type is frozen.
3703 -- To signal this case, Scalar_Range contains an unanalyzed syntactic
3704 -- range whose bounds are unanalyzed real literals. This routine will
3705 -- recognize this case, and transform this range node into a properly
3706 -- typed range with properly analyzed and resolved values.
3724 -- Returns size of type with given bounds. Also leaves these
3725 -- bounds set as the current bounds of the Typ.
3727 -----------
3728 -- Fsize --
3729 -----------
3732 begin
3738 -- Start of processing for Freeze_Fixed_Point_Type
3740 begin
3741 -- If Esize of a subtype has not previously been set, set it now
3748 else
3753 -- Immediate return if the range is already analyzed. This means
3754 -- that the range is already set, and does not need to be computed
3755 -- by this routine.
3761 -- Immediate return if either of the bounds raises Constraint_Error
3765 then
3772 -- Ordinary fixed-point case
3776 -- For the ordinary fixed-point case, we are allowed to fudge the
3777 -- end-points up or down by small. Generally we prefer to fudge
3778 -- up, i.e. widen the bounds for non-model numbers so that the
3779 -- end points are included. However there are cases in which this
3780 -- cannot be done, and indeed cases in which we may need to narrow
3781 -- the bounds. The following circuit makes the decision.
3783 -- Note: our terminology here is that Incl_EP means that the
3784 -- bounds are widened by Small if necessary to include the end
3785 -- points, and Excl_EP means that the bounds are narrowed by
3786 -- Small to exclude the end-points if this reduces the size.
3788 -- Note that in the Incl case, all we care about is including the
3789 -- end-points. In the Excl case, we want to narrow the bounds as
3790 -- much as permitted by the RM, to give the smallest possible size.
3807 begin
3808 -- First step. Base types are required to be symmetrical. Right
3809 -- now, the base type range is a copy of the first subtype range.
3810 -- This will be corrected before we are done, but right away we
3811 -- need to deal with the case where both bounds are non-negative.
3812 -- In this case, we set the low bound to the negative of the high
3813 -- bound, to make sure that the size is computed to include the
3814 -- required sign. Note that we do not need to worry about the
3815 -- case of both bounds negative, because the sign will be dealt
3816 -- with anyway. Furthermore we can't just go making such a bound
3817 -- symmetrical, since in a twos-complement system, there is an
3818 -- extra negative value which could not be accomodated on the
3819 -- positive side.
3824 then
3829 -- Compute the fudged bounds. If the number is a model number,
3830 -- then we do nothing to include it, but we are allowed to
3831 -- backoff to the next adjacent model number when we exclude
3832 -- it. If it is not a model number then we straddle the two
3833 -- values with the model numbers on either side.
3839 else
3843 -- The low value excluding the end point is Small greater, but
3844 -- we do not do this exclusion if the low value is positive,
3845 -- since it can't help the size and could actually hurt by
3846 -- crossing the high bound.
3850 else
3854 -- Similar processing for upper bound and high value
3860 else
3866 else
3870 -- One further adjustment is needed. In the case of subtypes,
3871 -- we cannot go outside the range of the base type, or we get
3872 -- peculiarities, and the base type range is already set. This
3873 -- only applies to the Incl values, since clearly the Excl
3874 -- values are already as restricted as they are allowed to be.
3881 -- Get size including and excluding end points
3886 -- No need to exclude end-points if it does not reduce size
3896 -- Now we set the actual size to be used. We want to use the
3897 -- bounds fudged up to include the end-points but only if this
3898 -- can be done without violating a specifically given size
3899 -- size clause or causing an unacceptable increase in size.
3901 -- Case of size clause given
3905 -- Use the inclusive size only if it is consistent with
3906 -- the explicitly specified size.
3913 -- If the inclusive size is too large, we try excluding
3914 -- the end-points (will be caught later if does not work).
3916 else
3922 -- Case of size clause not given
3924 else
3925 -- If we have a base type whose corresponding first subtype
3926 -- has an explicit size that is large enough to include our
3927 -- end-points, then do so. There is no point in working hard
3928 -- to get a base type whose size is smaller than the specified
3929 -- size of the first subtype.
3935 then
3940 -- If excluding the end-points makes the size smaller and
3941 -- results in a size of 8,16,32,64, then we take the smaller
3942 -- size. For the 64 case, this is compulsory. For the other
3943 -- cases, it seems reasonable. We like to include end points
3944 -- if we can, but not at the expense of moving to the next
3945 -- natural boundary of size.
3948 and then
3953 then
3958 -- Otherwise we can definitely include the end points
3960 else
3966 -- One pathological case: normally we never fudge a low
3967 -- bound down, since it would seem to increase the size
3968 -- (if it has any effect), but for ranges containing a
3969 -- single value, or no values, the high bound can be
3970 -- small too large. Consider:
3972 -- type t is delta 2.0**(-14)
3973 -- range 131072.0 .. 0;
3975 -- That lower bound is *just* outside the range of 32
3976 -- bits, and does need fudging down in this case. Note
3977 -- that the bounds will always have crossed here, since
3978 -- the high bound will be fudged down if necessary, as
3979 -- in the case of:
3981 -- type t is delta 2.0**(-14)
3982 -- range 131072.0 .. 131072.0;
3984 -- So we can detect the situation by looking for crossed
3985 -- bounds, and if the bounds are crossed, and the low
3986 -- bound is greater than zero, we will always back it
3987 -- off by small, since this is completely harmless.
3994 -- And of course, we need to do exactly the same parallel
3995 -- fudge for flat ranges in the negative region.
4008 -- For the decimal case, none of this fudging is required, since there
4009 -- are no end-point problems in the decimal case (the end-points are
4010 -- always included).
4012 else
4016 -- At this stage, the actual size has been calculated and the proper
4017 -- required bounds are stored in the low and high bounds.
4021 Error_Msg_N
4026 -- Check size against explicit given size
4032 Error_Msg_NE
4036 else
4040 -- Increase size to next natural boundary if no size clause given
4042 else
4049 else
4057 -- If we have a base type, then expand the bounds so that they
4058 -- extend to the full width of the allocated size in bits, to
4059 -- avoid junk range checks on intermediate computations.
4066 -- Final step is to reanalyze the bounds using the proper type
4067 -- and set the Corresponding_Integer_Value fields of the literals.
4073 -- Resolve with universal fixed if the base type, and the base
4074 -- type if it is a subtype. Note we can't resolve the base type
4075 -- with itself, that would be a reference before definition.
4079 else
4083 -- Set corresponding integer value for bound
4085 Set_Corresponding_Integer_Value
4088 -- Similar processing for high bound
4096 else
4100 Set_Corresponding_Integer_Value
4103 -- Set type of range to correspond to bounds
4107 -- Set Esize to calculated size if not set already
4113 -- Set RM_Size if not already set. If already set, check value
4115 declare
4118 begin
4123 Error_Msg_NE
4128 else
4134 ------------------
4135 -- Freeze_Itype --
4136 ------------------
4141 begin
4150 --------------------------
4151 -- Freeze_Static_Object --
4152 --------------------------
4157 -- Exception raised if the type of a static object cannot be made
4158 -- static. This happens if the type depends on non-global objects.
4161 -- Called to ensure that an expression used as part of a type
4162 -- definition is statically allocatable, which means that the type
4163 -- of the expression is statically allocatable, and the expression
4164 -- is either static, or a reference to a library level constant.
4167 -- Called to mark a type as static, checking that it is possible
4168 -- to set the type as static. If it is not possible, then the
4169 -- exception Cannot_Be_Static is raised.
4171 -----------------------------
4172 -- Ensure_Expression_Is_SA --
4173 -----------------------------
4178 begin
4190 then
4198 -----------------------
4199 -- Ensure_Type_Is_SA --
4200 -----------------------
4206 begin
4207 -- If type is library level, we are all set
4213 -- We are also OK if the type is already marked as statically
4214 -- allocated, which means we processed it before.
4220 -- Mark type as statically allocated
4224 -- Check that it is safe to statically allocate this type
4242 declare
4246 begin
4259 else
4269 then
4288 else
4293 -- Start of processing for Freeze_Static_Object
4295 begin
4298 -- Reset True_Constant flag, since something strange is going on
4299 -- with the scoping here, and our simple value tracing may not
4300 -- be sufficient for this indication to be reliable. We kill the
4301 -- Constant_Value indication for the same reason.
4306 exception
4309 -- If the object that cannot be static is imported or exported,
4310 -- then we give an error message saying that this object cannot
4311 -- be imported or exported.
4314 Error_Msg_N
4317 -- Otherwise must be exported, something is wrong if compiler
4318 -- is marking something as statically allocated which cannot be).
4321 Error_Msg_N
4326 -----------------------
4327 -- Freeze_Subprogram --
4328 -----------------------
4334 begin
4335 -- Subprogram may not have an address clause unless it is imported
4339 Error_Msg_N
4346 -- Reset the Pure indication on an imported subprogram unless an
4347 -- explicit Pure_Function pragma was present. We do this because
4348 -- otherwise it is an insidious error to call a non-pure function
4349 -- from a pure unit and have calls mysteriously optimized away.
4350 -- What happens here is that the Import can bypass the normal
4351 -- check to ensure that pure units call only pure subprograms.
4356 then
4360 -- For non-foreign convention subprograms, this is where we create
4361 -- the extra formals (for accessibility level and constrained bit
4362 -- information). We delay this till the freeze point precisely so
4363 -- that we know the convention!
4369 -- If this is convention Ada and a Valued_Procedure, that's odd
4374 and then Warn_On_Export_Import
4375 then
4376 Error_Msg_N
4381 -- Case of foreign convention
4383 else
4386 -- For foreign conventions, warn about return of an
4387 -- unconstrained array.
4389 -- Note: we *do* allow a return by descriptor for the VMS case,
4390 -- though here there is probably more to be done ???
4395 -- If no return type, probably some other error, e.g. a
4396 -- missing full declaration, so ignore.
4401 -- If the return type is generic, we have emitted a warning
4402 -- earlier on, and there is nothing else to check here.
4403 -- Specific instantiations may lead to erroneous behavior.
4411 and then Warn_On_Export_Import
4412 then
4413 Error_Msg_N
4420 -- If any of the formals for an exported foreign convention
4421 -- subprogram have defaults, then emit an appropriate warning
4422 -- since this is odd (default cannot be used from non-Ada code)
4427 if Warn_On_Export_Import
4429 then
4430 Error_Msg_N
4440 -- For VMS, descriptor mechanisms for parameters are allowed only
4441 -- for imported subprograms.
4448 Error_Msg_N
4450 Error_Msg_N
4460 ----------------------
4461 -- Is_Fully_Defined --
4462 ----------------------
4465 begin
4474 then
4475 -- Verify that the record type has no components with
4476 -- private types without completion.
4478 declare
4481 begin
4499 ---------------------------------
4500 -- Process_Default_Expressions --
4501 ---------------------------------
4503 procedure Process_Default_Expressions
4506 is
4513 begin
4516 -- A subprogram instance and its associated anonymous subprogram
4517 -- share their signature. The default expression functions are defined
4518 -- in the wrapper packages for the anonymous subprogram, and should
4519 -- not be generated again for the instance.
4524 then
4533 -- We work with a copy of the default expression because we
4534 -- do not want to disturb the original, since this would mess
4535 -- up the conformance checking.
4539 -- The analysis of the expression may generate insert actions,
4540 -- which of course must not be executed. We wrap those actions
4541 -- in a procedure that is not called, and later on eliminated.
4542 -- The following cases have no side-effects, and are analyzed
4543 -- directly.
4554 and then
4556 then
4558 -- If there is no default function, we must still do a full
4559 -- analyze call on the default value, to ensure that all
4560 -- error checks are performed, e.g. those associated with
4561 -- static evaluation. Note that this branch will always be
4562 -- taken if the analyzer is turned off (but we still need the
4563 -- error checks).
4565 -- Note: the setting of parent here is to meet the requirement
4566 -- that we can only analyze the expression while attached to
4567 -- the tree. Really the requirement is that the parent chain
4568 -- be set, we don't actually need to be in the tree.
4573 -- Default expressions are resolved with their own type if the
4574 -- context is generic, to avoid anomalies with private types.
4578 else
4582 -- If that resolved expression will raise constraint error,
4583 -- then flag the default value as raising constraint error.
4584 -- This allows a proper error message on the calls.
4590 -- If the default is a parameterless call, we use the name of
4591 -- the called function directly, and there is no body to build.
4595 then
4598 -- Else construct and analyze the body of a wrapper procedure
4599 -- that contains an object declaration to hold the expression.
4600 -- Given that this is done only to complete the analysis, it
4601 -- simpler to build a procedure than a function which might
4602 -- involve secondary stack expansion.
4604 else
4605 Dnam :=
4608 Dbody :=
4610 Specification =>
4616 Defining_Identifier =>
4619 Object_Definition =>
4623 Handled_Statement_Sequence =>
4641 ----------------------------------------
4642 -- Set_Component_Alignment_If_Not_Set --
4643 ----------------------------------------
4646 begin
4647 -- Ignore if not base type, subtypes don't need anything
4653 -- Do not override existing representation
4664 else
4665 Set_Component_Alignment
4671 ---------------------------
4672 -- Set_Debug_Info_Needed --
4673 ---------------------------
4676 begin
4680 then
4682 else
4693 declare
4695 begin
4705 declare
4707 begin
4730 ------------------
4731 -- Warn_Overlay --
4732 ------------------
4734 procedure Warn_Overlay
4738 is
4740 -- The object to which the address clause applies.
4746 begin
4747 -- No warning if address clause overlay warnings are off
4753 -- No warning if there is an explicit initialization
4761 -- We only give the warning for non-imported entities of a type
4762 -- for which a non-null base init proc is defined (or for access
4763 -- types which have implicit null initialization).
4769 then
4772 then
4777 then
4784 then
4791 -- A function call (most likely to To_Address) is probably not
4792 -- an overlay, so skip warning. Ditto if the function call was
4793 -- inlined and transformed into an entity.
4801 -- If a pragma Import follows, we assume that it is for the current
4802 -- target of the address clause, and skip the warning.
4807 then
4813 Error_Msg_N
4815 Nam);
4816 else
4817 Error_Msg_N
4819 Nam);
4822 -- Add friendly warning if initialization comes from a packed array
4823 -- component.
4826 declare
4829 begin
4835 then
4839 then
4840 Error_Msg_NE
4844 else
4851 Error_Msg_N
4854 Nam);