| blob | 6a808a35a30eb567a9902c8e2b3da5590bf05882 |
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- E X P _ C H 5 --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2016, 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 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
20 -- --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
23 -- --
24 ------------------------------------------------------------------------------
67 procedure Build_Formal_Container_Iteration
74 -- Utility to create declarations and loop statement for both forms
75 -- of formal container iterators.
78 -- Determine if the right-hand side of assignment N is a type conversion
79 -- which requires a change of representation. Called only for the array
80 -- and record cases.
83 -- N is an assignment which assigns an array value. This routine process
84 -- the various special cases and checks required for such assignments,
85 -- including change of representation. Rhs is normally simply the right-
86 -- hand side of the assignment, except that if the right-hand side is a
87 -- type conversion or a qualified expression, then the RHS is the actual
88 -- expression inside any such type conversions or qualifications.
90 function Expand_Assign_Array_Loop
98 -- N is an assignment statement which assigns an array value. This routine
99 -- expands the assignment into a loop (or nested loops for the case of a
100 -- multi-dimensional array) to do the assignment component by component.
101 -- Larray and Rarray are the entities of the actual arrays on the left-hand
102 -- and right-hand sides. L_Type and R_Type are the types of these arrays
103 -- (which may not be the same, due to either sliding, or to a change of
104 -- representation case). Ndim is the number of dimensions and the parameter
105 -- Rev indicates if the loops run normally (Rev = False), or reversed
106 -- (Rev = True). The value returned is the constructed loop statement.
107 -- Auxiliary declarations are inserted before node N using the standard
108 -- Insert_Actions mechanism.
111 -- N is an assignment of an untagged record value. This routine handles
112 -- the case where the assignment must be made component by component,
113 -- either because the target is not byte aligned, or there is a change
114 -- of representation, or when we have a tagged type with a representation
115 -- clause (this last case is required because holes in the tagged type
116 -- might be filled with components from child types).
119 -- (AI12-0125): N is an assignment statement whose RHS contains occurrences
120 -- of @ that designate the value of the LHS of the assignment. If the LHS
121 -- is side-effect free the target names can be replaced with a copy of the
122 -- LHS; otherwise the semantics of the assignment is described in terms of
123 -- a procedure with an in-out parameter, and expanded as such.
126 -- Use the primitives specified in an Iterable aspect to expand a loop
127 -- over a so-called formal container, primarily for SPARK usage.
130 -- Same, for an iterator of the form " For E of C". In this case the
131 -- iterator provides the name of the element, and the cursor is generated
132 -- internally.
135 -- Expand loop over arrays and containers that uses the form "for X of C"
136 -- with an optional subtype mark, or "for Y in C".
138 procedure Expand_Iterator_Loop_Over_Container
144 -- Expand loop over containers that uses the form "for X of C" with an
145 -- optional subtype mark, or "for Y in C". Isc is the iteration scheme.
146 -- I_Spec is the iterator specification and Container is either the
147 -- Container (for OF) or the iterator (for IN).
150 -- Expand for loop over predicated subtype
153 -- Generate the necessary code for controlled and tagged assignment, that
154 -- is to say, finalization of the target before, adjustment of the target
155 -- after and save and restore of the tag and finalization pointers which
156 -- are not 'part of the value' and must not be changed upon assignment. N
157 -- is the original Assignment node.
159 --------------------------------------
160 -- Build_Formal_Container_iteration --
161 --------------------------------------
163 procedure Build_Formal_Container_Iteration
170 is
181 begin
182 -- Declaration for Cursor
184 Init :=
188 Expression =>
194 -- Statement that advances cursor in loop
196 Advance :=
199 Expression =>
206 -- Iterator is rewritten as a while_loop
208 New_Loop :=
210 Iteration_Scheme =>
212 Condition =>
222 ------------------------------
223 -- Change_Of_Representation --
224 ------------------------------
228 begin
229 return
231 and then
235 -------------------------
236 -- Expand_Assign_Array --
237 -------------------------
239 -- There are two issues here. First, do we let Gigi do a block move, or
240 -- do we expand out into a loop? Second, we need to set the two flags
241 -- Forwards_OK and Backwards_OK which show whether the block move (or
242 -- corresponding loops) can be legitimately done in a forwards (low to
243 -- high) or backwards (high to low) manner.
269 -- This switch is set to True if the array move must be done using
270 -- an explicit front end generated loop.
273 -- If the argument is an access to an array, and the assignment is
274 -- converted into a procedure call, apply explicit dereference.
277 -- Test if Exp is a reference to an array whose declaration has
278 -- an address clause, or it is a slice of such an array.
281 -- Test if Exp is a reference to an array which is either a formal
282 -- parameter or a slice of a formal parameter. These are the cases
283 -- where hidden aliasing can occur.
286 -- Determine if Exp is a reference to an array variable which is other
287 -- than an object defined in the current scope, or a component or a
288 -- slice of such an object. Such objects can be aliased to parameters
289 -- (unlike local array references).
291 -----------------------
292 -- Apply_Dereference --
293 -----------------------
297 begin
305 ------------------------
306 -- Has_Address_Clause --
307 ------------------------
310 begin
311 return
314 or else
318 ---------------------
319 -- Is_Formal_Array --
320 ---------------------
323 begin
324 return
326 or else
330 ------------------------
331 -- Is_Non_Local_Array --
332 ------------------------
335 begin
337 when N_Indexed_Component
338 | N_Selected_Component
339 | N_Slice
340 =>
344 return
350 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
358 -- Start of processing for Expand_Assign_Array
360 begin
361 -- Deal with length check. Note that the length check is done with
362 -- respect to the right-hand side as given, not a possible underlying
363 -- renamed object, since this would generate incorrect extra checks.
367 -- We start by assuming that the move can be done in either direction,
368 -- i.e. that the two sides are completely disjoint.
373 -- Normally it is only the slice case that can lead to overlap, and
374 -- explicit checks for slices are made below. But there is one case
375 -- where the slice can be implicit and invisible to us: when we have a
376 -- one dimensional array, and either both operands are parameters, or
377 -- one is a parameter (which can be a slice passed by reference) and the
378 -- other is a non-local variable. In this case the parameter could be a
379 -- slice that overlaps with the other operand.
381 -- However, if the array subtype is a constrained first subtype in the
382 -- parameter case, then we don't have to worry about overlap, since
383 -- slice assignments aren't possible (other than for a slice denoting
384 -- the whole array).
386 -- Note: No overlap is possible if there is a change of representation,
387 -- so we can exclude this case.
390 and then not Crep
391 and then
393 or else
395 or else
397 and then
400 then
404 -- Note: the bit-packed case is not worrisome here, since if we have
405 -- a slice passed as a parameter, it is always aligned on a byte
406 -- boundary, and if there are no explicit slices, the assignment
407 -- can be performed directly.
410 -- If either operand has an address clause clear Backwards_OK and
411 -- Forwards_OK, since we cannot tell if the operands overlap. We
412 -- exclude this treatment when Rhs is an aggregate, since we know
413 -- that overlap can't occur.
417 then
422 -- We certainly must use a loop for change of representation and also
423 -- we use the operand of the conversion on the right-hand side as the
424 -- effective right-hand side (the component types must match in this
425 -- situation).
432 -- We require a loop if the left side is possibly bit unaligned
435 or else
437 then
440 -- Arrays with controlled components are expanded into a loop to force
441 -- calls to Adjust at the component level.
446 -- If object is atomic/VFA, we cannot tolerate a loop
449 or else
451 then
454 -- Loop is required if we have atomic components since we have to
455 -- be sure to do any accesses on an element by element basis.
461 then
464 -- Case where no slice is involved
468 -- The following code deals with the case of unconstrained bit packed
469 -- arrays. The problem is that the template for such arrays contains
470 -- the bounds of the actual source level array, but the copy of an
471 -- entire array requires the bounds of the underlying array. It would
472 -- be nice if the back end could take care of this, but right now it
473 -- does not know how, so if we have such a type, then we expand out
474 -- into a loop, which is inefficient but works correctly. If we don't
475 -- do this, we get the wrong length computed for the array to be
476 -- moved. The two cases we need to worry about are:
478 -- Explicit dereference of an unconstrained packed array type as in
479 -- the following example:
481 -- procedure C52 is
482 -- type BITS is array(INTEGER range <>) of BOOLEAN;
483 -- pragma PACK(BITS);
484 -- type A is access BITS;
485 -- P1,P2 : A;
486 -- begin
487 -- P1 := new BITS (1 .. 65_535);
488 -- P2 := new BITS (1 .. 65_535);
489 -- P2.ALL := P1.ALL;
490 -- end C52;
492 -- A formal parameter reference with an unconstrained bit array type
493 -- is the other case we need to worry about (here we assume the same
494 -- BITS type declared above):
496 -- procedure Write_All (File : out BITS; Contents : BITS);
497 -- begin
498 -- File.Storage := Contents;
499 -- end Write_All;
501 -- We expand to a loop in either of these two cases
503 -- Question for future thought. Another potentially more efficient
504 -- approach would be to create the actual subtype, and then do an
505 -- unchecked conversion to this actual subtype ???
510 -- Function to perform required test for the first case, above
511 -- (dereference of an unconstrained bit packed array).
513 -----------------------
514 -- Is_UBPA_Reference --
515 -----------------------
522 begin
526 then
535 else
537 return
542 else
547 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
549 begin
551 or else
553 then
556 -- Here if we do not have the case of a reference to a bit packed
557 -- unconstrained array case. In this case gigi can most certainly
558 -- handle the assignment if a forwards move is allowed.
560 -- (could it handle the backwards case also???)
567 -- The back end can always handle the assignment if the right side is a
568 -- string literal (note that overlap is definitely impossible in this
569 -- case). If the type is packed, a string literal is always converted
570 -- into an aggregate, except in the case of a null slice, for which no
571 -- aggregate can be written. In that case, rewrite the assignment as a
572 -- null statement, a length check has already been emitted to verify
573 -- that the range of the left-hand side is empty.
575 -- Note that this code is not executed if we have an assignment of a
576 -- string literal to a non-bit aligned component of a record, a case
577 -- which cannot be handled by the backend.
582 then
589 -- If either operand is bit packed, then we need a loop, since we can't
590 -- be sure that the slice is byte aligned. Similarly, if either operand
591 -- is a possibly unaligned slice, then we need a loop (since the back
592 -- end cannot handle unaligned slices).
598 then
601 -- If we are not bit-packed, and we have only one slice, then no overlap
602 -- is possible except in the parameter case, so we can let the back end
603 -- handle things.
611 -- If the right-hand side is a string literal, introduce a temporary for
612 -- it, for use in the generated loop that will follow.
615 declare
619 begin
620 Decl :=
632 -- Come here to complete the analysis
634 -- Loop_Required: Set to True if we know that a loop is required
635 -- regardless of overlap considerations.
637 -- Forwards_OK: Set to False if we already know that a forwards
638 -- move is not safe, else set to True.
640 -- Backwards_OK: Set to False if we already know that a backwards
641 -- move is not safe, else set to True
643 -- Our task at this stage is to complete the overlap analysis, which can
644 -- result in possibly setting Forwards_OK or Backwards_OK to False, and
645 -- then generating the final code, either by deciding that it is OK
646 -- after all to let Gigi handle it, or by generating appropriate code
647 -- in the front end.
649 declare
667 begin
668 -- Get the expressions for the arrays. If we are dealing with a
669 -- private type, then convert to the underlying type. We can do
670 -- direct assignments to an array that is a private type, but we
671 -- cannot assign to elements of the array without this extra
672 -- unchecked conversion.
674 -- Note: We propagate Parent to the conversion nodes to generate
675 -- a well-formed subtree.
679 else
683 declare
685 begin
686 Larray :=
687 Unchecked_Convert_To
696 else
700 declare
702 begin
703 Rarray :=
704 Unchecked_Convert_To
711 -- If both sides are slices, we must figure out whether it is safe
712 -- to do the move in one direction or the other. It is always safe
713 -- if there is a change of representation since obviously two arrays
714 -- with different representations cannot possibly overlap.
720 -- If both left- and right-hand arrays are entity names, and refer
721 -- to different entities, then we know that the move is safe (the
722 -- two storage areas are completely disjoint).
727 then
730 -- Otherwise, we assume the worst, which is that the two arrays
731 -- are the same array. There is no need to check if we know that
732 -- is the case, because if we don't know it, we still have to
733 -- assume it.
735 -- Generally if the same array is involved, then we have an
736 -- overlapping case. We will have to really assume the worst (i.e.
737 -- set neither of the OK flags) unless we can determine the lower
738 -- or upper bounds at compile time and compare them.
740 else
741 Cresult :=
742 Compile_Time_Compare
746 Cresult :=
747 Compile_Time_Compare
765 -- If after that analysis Loop_Required is False, meaning that we
766 -- have not discovered some non-overlap reason for requiring a loop,
767 -- then the outcome depends on the capabilities of the back end.
770 -- Assume the back end can deal with all cases of overlap by
771 -- falling back to memmove if it cannot use a more efficient
772 -- approach.
777 -- At this stage we have to generate an explicit loop, and we have
778 -- the following cases:
780 -- Forwards_OK = True
782 -- Rnn : right_index := right_index'First;
783 -- for Lnn in left-index loop
784 -- left (Lnn) := right (Rnn);
785 -- Rnn := right_index'Succ (Rnn);
786 -- end loop;
788 -- Note: the above code MUST be analyzed with checks off, because
789 -- otherwise the Succ could overflow. But in any case this is more
790 -- efficient.
792 -- Forwards_OK = False, Backwards_OK = True
794 -- Rnn : right_index := right_index'Last;
795 -- for Lnn in reverse left-index loop
796 -- left (Lnn) := right (Rnn);
797 -- Rnn := right_index'Pred (Rnn);
798 -- end loop;
800 -- Note: the above code MUST be analyzed with checks off, because
801 -- otherwise the Pred could overflow. But in any case this is more
802 -- efficient.
804 -- Forwards_OK = Backwards_OK = False
806 -- This only happens if we have the same array on each side. It is
807 -- possible to create situations using overlays that violate this,
808 -- but we simply do not promise to get this "right" in this case.
810 -- There are two possible subcases. If the No_Implicit_Conditionals
811 -- restriction is set, then we generate the following code:
813 -- declare
814 -- T : constant <operand-type> := rhs;
815 -- begin
816 -- lhs := T;
817 -- end;
819 -- If implicit conditionals are permitted, then we generate:
821 -- if Left_Lo <= Right_Lo then
822 -- <code for Forwards_OK = True above>
823 -- else
824 -- <code for Backwards_OK = True above>
825 -- end if;
827 -- In order to detect possible aliasing, we examine the renamed
828 -- expression when the source or target is a renaming. However,
829 -- the renaming may be intended to capture an address that may be
830 -- affected by subsequent code, and therefore we must recover
831 -- the actual entity for the expansion that follows, not the
832 -- object it renames. In particular, if source or target designate
833 -- a portion of a dynamically allocated object, the pointer to it
834 -- may be reassigned but the renaming preserves the proper location.
837 and then
840 then
845 and then
848 then
852 -- Cases where either Forwards_OK or Backwards_OK is true
859 then
860 declare
865 begin
877 New_Occurrence_Of (
886 else
888 Expand_Assign_Array_Loop
893 -- Case of both are false with No_Implicit_Conditionals
896 declare
900 begin
907 Object_Definition =>
911 Handled_Statement_Sequence =>
919 -- Case of both are false with implicit conditionals allowed
921 else
922 -- Before we generate this code, we must ensure that the left and
923 -- right side array types are defined. They may be itypes, and we
924 -- cannot let them be defined inside the if, since the first use
925 -- in the then may not be executed.
930 -- We normally compare addresses to find out which way round to
931 -- do the loop, since this is reliable, and handles the cases of
932 -- parameters, conversions etc. But we can't do that in the bit
933 -- packed case, because addresses don't work there.
936 Condition :=
938 Left_Opnd =>
941 Prefix =>
943 Prefix =>
947 Prefix =>
948 New_Occurrence_Of
953 Right_Opnd =>
956 Prefix =>
958 Prefix =>
962 Prefix =>
963 New_Occurrence_Of
968 -- For the bit packed and VM cases we use the bounds. That's OK,
969 -- because we don't have to worry about parameters, since they
970 -- cannot cause overlap. Perhaps we should worry about weird slice
971 -- conversions ???
973 else
974 -- Copy the bounds
979 -- If the types do not match we add an implicit conversion
980 -- here to ensure proper match
983 Cright_Lo :=
987 -- Reset the Analyzed flag, because the bounds of the index
988 -- type itself may be universal, and must must be reanalyzed
989 -- to acquire the proper type for the back end.
994 Condition :=
1004 then
1006 -- Call TSS procedure for array assignment, passing the
1007 -- explicit bounds of right- and left-hand sides.
1009 declare
1014 begin
1035 else
1041 Expand_Assign_Array_Loop
1046 Expand_Assign_Array_Loop
1055 exception
1060 ------------------------------
1061 -- Expand_Assign_Array_Loop --
1062 ------------------------------
1064 -- The following is an example of the loop generated for the case of a
1065 -- two-dimensional array:
1067 -- declare
1068 -- R2b : Tm1X1 := 1;
1069 -- begin
1070 -- for L1b in 1 .. 100 loop
1071 -- declare
1072 -- R4b : Tm1X2 := 1;
1073 -- begin
1074 -- for L3b in 1 .. 100 loop
1075 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
1076 -- R4b := Tm1X2'succ(R4b);
1077 -- end loop;
1078 -- end;
1079 -- R2b := Tm1X1'succ(R2b);
1080 -- end loop;
1081 -- end;
1083 -- Here Rev is False, and Tm1Xn are the subscript types for the right-hand
1084 -- side. The declarations of R2b and R4b are inserted before the original
1085 -- assignment statement.
1087 function Expand_Assign_Array_Loop
1095 is
1100 -- Entities used as subscripts on left and right sides
1104 -- Left and right index types
1112 -- The increment step for the index of the right-hand side is written
1113 -- as an attribute reference (Succ or Pred). This function returns
1114 -- the corresponding node, which is placed at the end of the loop body.
1116 ----------------
1117 -- Build_Step --
1118 ----------------
1124 begin
1127 else
1131 Step :=
1134 Expression =>
1136 Prefix =>
1142 -- Note that on the last iteration of the loop, the index is increased
1143 -- (or decreased) past the corresponding bound. This is consistent with
1144 -- the C semantics of the back-end, where such an off-by-one value on a
1145 -- dead index variable is OK. However, in CodePeer mode this leads to
1146 -- spurious warnings, and thus we place a guard around the attribute
1147 -- reference. For obvious reasons we only do this for CodePeer.
1150 Step :=
1152 Condition =>
1155 Right_Opnd =>
1165 -- Start of processing for Expand_Assign_Array_Loop
1167 begin
1171 else
1176 -- Setup index types and subscript entities
1178 declare
1182 begin
1198 -- Now construct the assignment statement
1200 declare
1204 begin
1210 Assign :=
1212 Name =>
1216 Expression =>
1221 -- We set assignment OK, since there are some cases, e.g. in object
1222 -- declarations, where we are actually assigning into a constant.
1223 -- If there really is an illegality, it was caught long before now,
1224 -- and was flagged when the original assignment was analyzed.
1228 -- Propagate the No_Ctrl_Actions flag to individual assignments
1233 -- Now construct the loop from the inside out, with the last subscript
1234 -- varying most rapidly. Note that Assign is first the raw assignment
1235 -- statement, and then subsequently the loop that wraps it up.
1238 Assign :=
1243 Object_Definition =>
1245 Expression =>
1250 Handled_Statement_Sequence =>
1254 Iteration_Scheme =>
1256 Loop_Parameter_Specification =>
1260 Discrete_Subtype_Definition =>
1269 --------------------------
1270 -- Expand_Assign_Record --
1271 --------------------------
1278 begin
1279 -- If change of representation, then extract the real right-hand side
1280 -- from the type conversion, and proceed with component-wise assignment,
1281 -- since the two types are not the same as far as the back end is
1282 -- concerned.
1287 -- If this may be a case of a large bit aligned component, then proceed
1288 -- with component-wise assignment, to avoid possible clobbering of other
1289 -- components sharing bits in the first or last byte of the component to
1290 -- be assigned.
1293 or
1295 then
1298 -- If we have a tagged type that has a complete record representation
1299 -- clause, we must do we must do component-wise assignments, since child
1300 -- types may have used gaps for their components, and we might be
1301 -- dealing with a view conversion.
1306 -- If neither condition met, then nothing special to do, the back end
1307 -- can handle assignment of the entire component as a single entity.
1309 else
1313 -- At this stage we know that we must do a component wise assignment
1315 declare
1322 function Find_Component
1325 -- Find the component with the given name in the underlying record
1326 -- declaration for Typ. We need to use the actual entity because the
1327 -- type may be private and resolution by identifier alone would fail.
1329 function Make_Component_List_Assign
1332 -- Returns a sequence of statements to assign the components that
1333 -- are referenced in the given component list. The flag U_U is
1334 -- used to force the usage of the inferred value of the variant
1335 -- part expression as the switch for the generated case statement.
1337 function Make_Field_Assign
1340 -- Given C, the entity for a discriminant or component, build an
1341 -- assignment for the corresponding field values. The flag U_U
1342 -- signals the presence of an Unchecked_Union and forces the usage
1343 -- of the inferred discriminant value of C as the right-hand side
1344 -- of the assignment.
1347 -- Given CI, a component items list, construct series of statements
1348 -- for fieldwise assignment of the corresponding components.
1350 --------------------
1351 -- Find_Component --
1352 --------------------
1354 function Find_Component
1357 is
1361 begin
1374 --------------------------------
1375 -- Make_Component_List_Assign --
1376 --------------------------------
1378 function Make_Component_List_Assign
1381 is
1392 begin
1409 Statements =>
1414 -- If we have an Unchecked_Union, use the value of the inferred
1415 -- discriminant of the variant part expression as the switch
1416 -- for the case statement. The case statement may later be
1417 -- folded.
1420 Expr :=
1425 else
1426 Expr :=
1429 Selector_Name =>
1442 -----------------------
1443 -- Make_Field_Assign --
1444 -----------------------
1446 function Make_Field_Assign
1449 is
1453 begin
1454 -- In the case of an Unchecked_Union, use the discriminant
1455 -- constraint value as on the right-hand side of the assignment.
1458 Expr :=
1462 else
1463 Expr :=
1469 A :=
1471 Name =>
1474 Selector_Name =>
1478 -- Set Assignment_OK, so discriminants can be assigned
1485 then
1492 ------------------------
1493 -- Make_Field_Assigns --
1494 ------------------------
1500 begin
1506 -- Look for components, but exclude _tag field assignment if
1507 -- the special Componentwise_Assignment flag is set.
1512 then
1513 Append_To
1523 -- Start of processing for Expand_Assign_Record
1525 begin
1526 -- Note that we use the base types for this processing. This results
1527 -- in some extra work in the constrained case, but the change of
1528 -- representation case is so unusual that it is not worth the effort.
1530 -- First copy the discriminants. This is done unconditionally. It
1531 -- is required in the unconstrained left side case, and also in the
1532 -- case where this assignment was constructed during the expansion
1533 -- of a type conversion (since initialization of discriminants is
1534 -- suppressed in this case). It is unnecessary but harmless in
1535 -- other cases.
1541 -- If we are expanding the initialization of a derived record
1542 -- that constrains or renames discriminants of the parent, we
1543 -- must use the corresponding discriminant in the parent.
1545 declare
1548 begin
1549 if Inside_Init_Proc
1551 then
1553 else
1559 -- Within an initialization procedure this is the
1560 -- assignment to an unchecked union component, in which
1561 -- case there is no discriminant to initialize.
1566 else
1567 -- The assignment is part of a conversion from a
1568 -- derived unchecked union type with an inferable
1569 -- discriminant, to a parent type.
1574 else
1583 -- We know the underlying type is a record, but its current view
1584 -- may be private. We must retrieve the usable record declaration.
1587 N_Private_Extension_Declaration)
1589 then
1591 else
1601 then
1605 else
1606 Insert_Actions
1615 -------------------------------------
1616 -- Expand_Assign_With_Target_Names --
1617 -------------------------------------
1626 -- The entity of the left-hand side
1629 -- Replace occurrences of the target name by the proper entity: either
1630 -- the entity of the LHS in simple cases, or the formal of the
1631 -- constructed procedure otherwise.
1633 --------------------
1634 -- Replace_Target --
1635 --------------------
1638 begin
1649 -- Local variables
1654 -- Start of processing for Expand_Assign_With_Target_Names
1656 begin
1659 -- The left-hand side is a direct name
1663 then
1667 -- Generate:
1668 -- LHS := ... LHS ...;
1675 -- The left-hand side is not a direct name, but is side-effect free.
1676 -- Capture its value in a temporary to avoid multiple evaluations.
1682 -- Generate:
1683 -- T : LHS_Typ := LHS;
1691 -- Generate:
1692 -- LHS := ... T ...;
1699 -- Otherwise wrap the whole assignment statement in a procedure with an
1700 -- IN OUT parameter. The original assignment then becomes a call to the
1701 -- procedure with the left-hand side as an actual.
1703 else
1707 -- Generate:
1708 -- procedure P (T : in out LHS_Typ) is
1709 -- begin
1710 -- T := ... T ...;
1711 -- end P;
1717 Specification =>
1725 Parameter_Type =>
1730 Handled_Statement_Sequence =>
1737 -- Generate:
1738 -- P (LHS);
1746 -- Analyze rewritten node, either as assignment or procedure call
1751 -----------------------------------
1752 -- Expand_N_Assignment_Statement --
1753 -----------------------------------
1755 -- This procedure implements various cases where an assignment statement
1756 -- cannot just be passed on to the back end in untransformed state.
1766 begin
1767 -- Special case to check right away, if the Componentwise_Assignment
1768 -- flag is set, this is a reanalysis from the expansion of the primitive
1769 -- assignment procedure for a tagged type, and all we need to do is to
1770 -- expand to assignment of components, because otherwise, we would get
1771 -- infinite recursion (since this looks like a tagged assignment which
1772 -- would normally try to *call* the primitive assignment procedure).
1779 -- Defend against invalid subscripts on left side if we are in standard
1780 -- validity checking mode. No need to do this if we are checking all
1781 -- subscripts.
1783 -- Note that we do this right away, because there are some early return
1784 -- paths in this procedure, and this is required on all paths.
1786 if Validity_Checks_On
1787 and then Validity_Check_Default
1788 and then not Validity_Check_Subscripts
1789 then
1793 -- Separate expansion if RHS contain target names. Note that assignment
1794 -- may already have been expanded if RHS is aggregate.
1801 -- Ada 2005 (AI-327): Handle assignment to priority of protected object
1803 -- Rewrite an assignment to X'Priority into a run-time call
1805 -- For example: X'Priority := New_Prio_Expr;
1806 -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr);
1808 -- Note that although X'Priority is notionally an object, it is quite
1809 -- deliberately not defined as an aliased object in the RM. This means
1810 -- that it works fine to rewrite it as a call, without having to worry
1811 -- about complications that would other arise from X'Priority'Access,
1812 -- which is illegal, because of the lack of aliasing.
1815 declare
1822 begin
1823 -- Handle chains of renamings
1829 loop
1833 -- The attribute Priority applied to protected objects has been
1834 -- previously expanded into a call to the Get_Ceiling run-time
1835 -- subprogram. In restricted profiles this is not available.
1839 -- Look for the enclosing concurrent type
1848 -- Generate the first actual of the call
1855 -- Select the appropriate run-time call
1858 RT_Subprg_Name :=
1860 else
1861 RT_Subprg_Name :=
1865 Call :=
1880 -- Deal with assignment checks unless suppressed
1884 -- First deal with generation of range check if required
1890 -- Then generate predicate check if required
1895 -- Check for a special case where a high level transformation is
1896 -- required. If we have either of:
1898 -- P.field := rhs;
1899 -- P (sub) := rhs;
1901 -- where P is a reference to a bit packed array, then we have to unwind
1902 -- the assignment. The exact meaning of being a reference to a bit
1903 -- packed array is as follows:
1905 -- An indexed component whose prefix is a bit packed array is a
1906 -- reference to a bit packed array.
1908 -- An indexed component or selected component whose prefix is a
1909 -- reference to a bit packed array is itself a reference ot a
1910 -- bit packed array.
1912 -- The required transformation is
1914 -- Tnn : prefix_type := P;
1915 -- Tnn.field := rhs;
1916 -- P := Tnn;
1918 -- or
1920 -- Tnn : prefix_type := P;
1921 -- Tnn (subscr) := rhs;
1922 -- P := Tnn;
1924 -- Since P is going to be evaluated more than once, any subscripts
1925 -- in P must have their evaluation forced.
1929 then
1930 declare
1936 begin
1937 -- Insert the post assignment first, because we want to copy the
1938 -- BPAR_Expr tree before it gets analyzed in the context of the
1939 -- pre assignment. Note that we do not analyze the post assignment
1940 -- yet (we cannot till we have completed the analysis of the pre
1941 -- assignment). As usual, the analysis of this post assignment
1942 -- will happen on its own when we "run into" it after finishing
1943 -- the current assignment.
1950 -- At this stage BPAR_Expr is a reference to a bit packed array
1951 -- where the reference was not expanded in the original tree,
1952 -- since it was on the left side of an assignment. But in the
1953 -- pre-assignment statement (the object definition), BPAR_Expr
1954 -- will end up on the right-hand side, and must be reexpanded. To
1955 -- achieve this, we reset the analyzed flag of all selected and
1956 -- indexed components down to the actual indexed component for
1957 -- the packed array.
1960 loop
1964 N_Selected_Component)
1965 then
1967 else
1972 -- Now we can insert and analyze the pre-assignment
1974 -- If the right-hand side requires a transient scope, it has
1975 -- already been placed on the stack. However, the declaration is
1976 -- inserted in the tree outside of this scope, and must reflect
1977 -- the proper scope for its variable. This awkward bit is forced
1978 -- by the stricter scope discipline imposed by GCC 2.97.
1980 declare
1982 Scope_Is_Transient
1985 begin
1997 Pop_Scope;
2001 -- Now fix up the original assignment and continue processing
2006 -- We do not need to reanalyze that assignment, and we do not need
2007 -- to worry about references to the temporary, but we do need to
2008 -- make sure that the temporary is not marked as a true constant
2009 -- since we now have a generated assignment to it.
2015 -- When we have the appropriate type of aggregate in the expression (it
2016 -- has been determined during analysis of the aggregate by setting the
2017 -- delay flag), let's perform in place assignment and thus avoid
2018 -- creating a temporary.
2028 -- Apply discriminant check if required. If Lhs is an access type to a
2029 -- designated type with discriminants, we must always check. If the
2030 -- type has unknown discriminants, more elaborate processing below.
2034 then
2035 -- Skip discriminant check if change of representation. Will be
2036 -- done when the change of representation is expanded out.
2042 -- If the type is private without discriminants, and the full type
2043 -- has discriminants (necessarily with defaults) a check may still be
2044 -- necessary if the Lhs is aliased. The private discriminants must be
2045 -- visible to build the discriminant constraints.
2047 -- Only an explicit dereference that comes from source indicates
2048 -- aliasing. Access to formals of protected operations and entries
2049 -- create dereferences but are not semantic aliasings.
2055 then
2056 declare
2060 begin
2061 -- In the case of an expander-generated record subtype whose base
2062 -- type still appears private, Typ will have been set to that
2063 -- private type rather than the underlying record type (because
2064 -- Underlying type will have returned the record subtype), so it's
2065 -- necessary to apply Underlying_Type again to the base type to
2066 -- get the record type we need for the discriminant check. Such
2067 -- subtypes can be created for assignments in certain cases, such
2068 -- as within an instantiation passed this kind of private type.
2069 -- It would be good to avoid this special test, but making changes
2070 -- to prevent this odd form of record subtype seems difficult. ???
2082 -- If the Lhs has a private type with unknown discriminants, it may
2083 -- have a full view with discriminants, but those are nameable only
2084 -- in the underlying type, so convert the Rhs to it before potential
2085 -- checking. Convert Lhs as well, otherwise the actual subtype might
2086 -- not be constructible. If the discriminants have defaults the type
2087 -- is unconstrained and there is nothing to check.
2092 then
2097 -- In the access type case, we need the same discriminant check, and
2098 -- also range checks if we have an access to constrained array.
2102 then
2105 -- Skip discriminant check if change of representation. Will be
2106 -- done when the change of representation is expanded out.
2120 declare
2124 begin
2125 C_Es :=
2126 Get_Range_Checks
2128 Target_Typ,
2131 Insert_Range_Checks
2133 N,
2134 Target_Typ,
2136 Lhs);
2141 -- Apply range check for access type case
2146 then
2148 Apply_Range_Check
2152 -- Ada 2005 (AI-231): Generate the run-time check
2158 -- If an actual is an out parameter of a null-excluding access
2159 -- type, there is access check on entry, so we set the flag
2160 -- Suppress_Assignment_Checks on the generated statement to
2161 -- assign the actual to the parameter block, and we do not want
2162 -- to generate an additional check at this point.
2165 then
2169 -- Ada 2012 (AI05-148): Update current accessibility level if Rhs is a
2170 -- stand-alone obj of an anonymous access type. Do not install the check
2171 -- when the Lhs denotes a container cursor and the Next function employs
2172 -- an access type, because this can never result in a dangling pointer.
2178 then
2179 declare
2181 -- Look through renames to find the underlying entity.
2182 -- For assignment to a rename, we don't care about the
2183 -- Enclosing_Dynamic_Scope of the rename declaration.
2185 ----------------
2186 -- Lhs_Entity --
2187 ----------------
2192 begin
2195 -- Renamed_Object must return an Entity_Name here
2196 -- because of preceding "Present (E_E_A (...))" test.
2204 -- Local Declarations
2208 Condition =>
2210 Left_Opnd =>
2212 Right_Opnd =>
2214 Intval =>
2215 Scope_Depth
2216 (Enclosing_Dynamic_Scope
2222 Name =>
2223 New_Occurrence_Of
2224 (Effective_Extra_Accessibility
2226 Expression =>
2229 begin
2238 -- Case of assignment to a bit packed array element. If there is a
2239 -- change of representation this must be expanded into components,
2240 -- otherwise this is a bit-field assignment.
2244 then
2245 -- Normal case, no change of representation
2251 -- Change of representation case
2253 else
2254 -- Generate the following, to force component-by-component
2255 -- assignments in an efficient way. Otherwise each component
2256 -- will require a temporary and two bit-field manipulations.
2258 -- T1 : Elmt_Type;
2259 -- T1 := RhS;
2260 -- Lhs := T1;
2262 declare
2266 begin
2267 Stats :=
2268 New_List (
2271 Object_Definition =>
2286 -- Build-in-place function call case. Note that we're not yet doing
2287 -- build-in-place for user-written assignment statements (the assignment
2288 -- here came from an aggregate.)
2292 then
2297 then
2302 begin
2303 -- In the controlled case, we ensure that function calls are
2304 -- evaluated before finalizing the target. In all cases, it makes
2305 -- the expansion easier if the side effects are removed first.
2310 -- Avoid recursion in the mechanism
2314 -- If dispatching assignment, we need to dispatch to _assign
2318 -- If the type is tagged, we may as well use the predefined
2319 -- primitive assignment. This avoids inlining a lot of code
2320 -- and in the class-wide case, the assignment is replaced
2321 -- by a dispatching call to _assign. It is suppressed in the
2322 -- case of assignments created by the expander that correspond
2323 -- to initializations, where we do want to copy the tag
2324 -- (Expand_Ctrl_Actions flag is set False in this case). It is
2325 -- also suppressed if restriction No_Dispatching_Calls is in
2326 -- force because in that case predefined primitives are not
2327 -- generated.
2331 and then Expand_Ctrl_Actions
2332 and then
2334 then
2337 -- This can happen in an instance when the formal is an
2338 -- extension of a limited interface, and the actual is
2339 -- limited. This is an error according to AI05-0087, but
2340 -- is not caught at the point of instantiation in earlier
2341 -- versions.
2343 -- This is wrong, error messages cannot be issued during
2344 -- expansion, since they would be missed in -gnatc mode ???
2350 -- Fetch the primitive op _assign and proper type to call it.
2351 -- Because of possible conflicts between private and full view,
2352 -- fetch the proper type directly from the operation profile.
2354 declare
2359 begin
2360 -- If the assignment is dispatching, make sure to use the
2361 -- proper type.
2369 -- In case of assignment to a class-wide tagged type, before
2370 -- the assignment we generate run-time check to ensure that
2371 -- the tags of source and target match.
2377 then
2378 declare
2382 begin
2384 Lhs_Tag :=
2387 Selector_Name =>
2389 Rhs_Tag :=
2392 Selector_Name =>
2394 else
2395 -- Displace the pointer to the base of the objects
2396 -- applying 'Address, which is later expanded into
2397 -- a call to RE_Base_Address.
2399 Lhs_Tag :=
2401 Prefix =>
2406 Rhs_Tag :=
2408 Prefix =>
2417 Condition =>
2425 declare
2429 begin
2430 -- In order to dispatch the call to _assign the type of
2431 -- the actuals must match. Add conversion (if required).
2450 else
2453 -- We can't afford to have destructive Finalization Actions in
2454 -- the Self assignment case, so if the target and the source
2455 -- are not obviously different, code is generated to avoid the
2456 -- self assignment case:
2458 -- if lhs'address /= rhs'address then
2459 -- <code for controlled and/or tagged assignment>
2460 -- end if;
2462 -- Skip this if Restriction (No_Finalization) is active
2465 and then Expand_Ctrl_Actions
2467 then
2470 Condition =>
2472 Left_Opnd =>
2477 Right_Opnd =>
2485 -- We need to set up an exception handler for implementing
2486 -- 7.6.1(18). The remaining adjustments are tackled by the
2487 -- implementation of adjust for record_controllers (see
2488 -- s-finimp.adb).
2490 -- This is skipped if we have no finalization
2492 if Expand_Ctrl_Actions
2494 then
2497 Handled_Statement_Sequence =>
2507 Handled_Statement_Sequence =>
2510 -- If no restrictions on aborts, protect the whole assignment
2511 -- for controlled objects as per 9.8(11).
2514 and then Expand_Ctrl_Actions
2515 and then Abort_Allowed
2516 then
2517 declare
2519 New_Internal_Entity
2523 begin
2534 -- Present the Abort_Undefer_Direct function to the backend
2535 -- so that it can inline the call to the function.
2539 Expand_At_End_Handler
2544 -- N has been rewritten to a block statement for which it is
2545 -- known by construction that no checks are necessary: analyze
2546 -- it with all checks suppressed.
2552 -- Array types
2555 declare
2558 begin
2560 N_Qualified_Expression)
2561 loop
2569 -- Record types
2575 -- Scalar types. This is where we perform the processing related to the
2576 -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid
2577 -- scalar values.
2581 -- Case where right side is known valid
2585 -- Here the right side is valid, so it is fine. The case to deal
2586 -- with is when the left side is a local variable reference whose
2587 -- value is not currently known to be valid. If this is the case,
2588 -- and the assignment appears in an unconditional context, then
2589 -- we can mark the left side as now being valid if one of these
2590 -- conditions holds:
2592 -- The expression of the right side has Do_Range_Check set so
2593 -- that we know a range check will be performed. Note that it
2594 -- can be the case that a range check is omitted because we
2595 -- make the assumption that we can assume validity for operands
2596 -- appearing in the right side in determining whether a range
2597 -- check is required
2599 -- The subtype of the right side matches the subtype of the
2600 -- left side. In this case, even though we have not checked
2601 -- the range of the right side, we know it is in range of its
2602 -- subtype if the expression is valid.
2607 then
2610 then
2615 -- Case where right side may be invalid in the sense of the RM
2616 -- reference above. The RM does not require that we check for the
2617 -- validity on an assignment, but it does require that the assignment
2618 -- of an invalid value not cause erroneous behavior.
2620 -- The general approach in GNAT is to use the Is_Known_Valid flag
2621 -- to avoid the need for validity checking on assignments. However
2622 -- in some cases, we have to do validity checking in order to make
2623 -- sure that the setting of this flag is correct.
2625 else
2626 -- Validate right side if we are validating copies
2628 if Validity_Checks_On
2629 and then Validity_Check_Copies
2630 then
2631 -- Skip this if left-hand side is an array or record component
2632 -- and elementary component validity checks are suppressed.
2635 and then not Validity_Check_Components
2636 then
2638 else
2642 -- We can propagate this to the left side where appropriate
2647 then
2651 -- Otherwise check to see what should be done
2653 -- If left side is a local variable, then we just set its flag to
2654 -- indicate that its value may no longer be valid, since we are
2655 -- copying a potentially invalid value.
2660 -- Check for case of a nonlocal variable on the left side which
2661 -- is currently known to be valid. In this case, we simply ensure
2662 -- that the right side is valid. We only play the game of copying
2663 -- validity status for local variables, since we are doing this
2664 -- statically, not by tracing the full flow graph.
2668 then
2669 -- Note: If Validity_Checking mode is set to none, we ignore
2670 -- the Ensure_Valid call so don't worry about that case here.
2674 -- In all other cases, we can safely copy an invalid value without
2675 -- worrying about the status of the left side. Since it is not a
2676 -- variable reference it will not be considered
2677 -- as being known to be valid in any case.
2679 else
2685 exception
2690 ------------------------------
2691 -- Expand_N_Block_Statement --
2692 ------------------------------
2694 -- Encode entity names defined in block statement
2697 begin
2701 -----------------------------
2702 -- Expand_N_Case_Statement --
2703 -----------------------------
2714 begin
2715 -- Check for the situation where we know at compile time which branch
2716 -- will be taken.
2718 -- If the value is static but its subtype is predicated and the value
2719 -- does not obey the predicate, the value is marked non-static, and
2720 -- there can be no corresponding static alternative. In that case we
2721 -- replace the case statement with an exception, regardless of whether
2722 -- assertions are enabled or not, unless predicates are ignored.
2728 then
2737 then
2740 -- Do not consider controlled objects found in a case statement which
2741 -- actually models a case expression because their early finalization
2742 -- will affect the result of the expression.
2748 -- Move statements from this alternative after the case statement.
2749 -- They are already analyzed, so will be skipped by the analyzer.
2753 -- That leaves the case statement as a shell. So now we can kill all
2754 -- other alternatives in the case statement.
2758 declare
2761 begin
2762 -- Loop through case alternatives, skipping pragmas, and skipping
2763 -- the one alternative that we select (and therefore retain).
2769 then
2781 -- Here if the choice is not determined at compile time
2783 declare
2792 begin
2796 else
2800 -- First step is to worry about possible invalid argument. The RM
2801 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
2802 -- outside the base range), then Constraint_Error must be raised.
2804 -- Case of validity check required (validity checks are on, the
2805 -- expression is not known to be valid, and the case statement
2806 -- comes from source -- no need to validity check internally
2807 -- generated case statements).
2809 if Validity_Check_Default
2811 then
2815 -- If there is only a single alternative, just replace it with the
2816 -- sequence of statements since obviously that is what is going to
2817 -- be executed in all cases.
2823 -- We still need to evaluate the expression if it has any side
2824 -- effects.
2829 -- Do not consider controlled objects found in a case statement
2830 -- which actually models a case expression because their early
2831 -- finalization will affect the result of the expression.
2839 -- That leaves the case statement as a shell. The alternative that
2840 -- will be executed is reset to a null list. So now we can kill
2841 -- the entire case statement.
2847 -- An optimization. If there are only two alternatives, and only
2848 -- a single choice, then rewrite the whole case statement as an
2849 -- if statement, since this can result in subsequent optimizations.
2850 -- This helps not only with case statements in the source of a
2851 -- simple form, but also with generated code (discriminant check
2852 -- functions in particular).
2854 -- Note: it is OK to do this before expanding out choices for any
2855 -- static predicates, since the if statement processing will handle
2856 -- the static predicate case fine.
2867 -- For TRUE, generate "expression", not expression = true
2871 then
2874 -- For FALSE, generate "expression" and switch then/else
2878 then
2883 -- For a range, generate "expression in range"
2890 then
2891 Cond :=
2896 -- A subtype indication is not a legal operator in a membership
2897 -- test, so retrieve its range.
2900 Cond :=
2903 Right_Opnd =>
2904 Relocate_Node
2907 -- For any other subexpression "expression = value"
2909 else
2910 Cond :=
2916 -- Now rewrite the case as an IF
2928 -- If the last alternative is not an Others choice, replace it with
2929 -- an N_Others_Choice. Note that we do not bother to call Analyze on
2930 -- the modified case statement, since it's only effect would be to
2931 -- compute the contents of the Others_Discrete_Choices which is not
2932 -- needed by the back end anyway.
2934 -- The reason for this is that the back end always needs some default
2935 -- for a switch, so if we have not supplied one in the processing
2936 -- above for validity checking, then we need to supply one here.
2941 -- If Predicates_Ignored is true the value does not satisfy the
2942 -- predicate, and there is no Others choice, Constraint_Error
2943 -- must be raised (4.5.7 (21/3)).
2946 declare
2956 begin
2961 else
2962 Set_Others_Discrete_Choices
2969 -- Deal with possible declarations of controlled objects, and also
2970 -- with rewriting choice sequences for static predicate references.
2975 -- Do not consider controlled objects found in a case statement
2976 -- which actually models a case expression because their early
2977 -- finalization will affect the result of the expression.
2992 -----------------------------
2993 -- Expand_N_Exit_Statement --
2994 -----------------------------
2996 -- The only processing required is to deal with a possible C/Fortran
2997 -- boolean value used as the condition for the exit statement.
3000 begin
3004 ----------------------------------
3005 -- Expand_Formal_Container_Loop --
3006 ----------------------------------
3021 begin
3022 -- The expansion resembles the one for Ada containers, but the
3023 -- primitives mention the domain of iteration explicitly, and
3024 -- function First applied to the container yields a cursor directly.
3026 -- Cursor : Cursor_type := First (Container);
3027 -- while Has_Element (Cursor, Container) loop
3028 -- <original loop statements>
3029 -- Cursor := Next (Container, Cursor);
3030 -- end loop;
3032 Build_Formal_Container_Iteration
3038 -- Build block to capture declaration of cursor entity.
3040 Blk_Nod :=
3043 Handled_Statement_Sequence =>
3051 ------------------------------------------
3052 -- Expand_Formal_Container_Element_Loop --
3053 ------------------------------------------
3077 begin
3078 -- For an element iterator, the Element aspect must be present,
3079 -- (this is checked during analysis) and the expansion takes the form:
3081 -- Cursor : Cursor_Type := First (Container);
3082 -- Elmt : Element_Type;
3083 -- while Has_Element (Cursor, Container) loop
3084 -- Elmt := Element (Container, Cursor);
3085 -- <original loop statements>
3086 -- Cursor := Next (Container, Cursor);
3087 -- end loop;
3089 -- However this expansion is not legal if the element is indefinite.
3090 -- In that case we create a block to hold a variable declaration
3091 -- initialized with a call to Element, and generate:
3093 -- Cursor : Cursor_Type := First (Container);
3094 -- while Has_Element (Cursor, Container) loop
3095 -- declare
3096 -- Elmt : Element_Type := Element (Container, Cursor);
3097 -- begin
3098 -- <original loop statements>
3099 -- Cursor := Next (Container, Cursor);
3100 -- end;
3101 -- end loop;
3103 Build_Formal_Container_Iteration
3110 -- Declaration for Element
3112 Elmt_Decl :=
3126 New_List
3129 Handled_Statement_Sequence =>
3133 else
3134 Elmt_Ref :=
3137 Expression =>
3146 -- The element is assignable in the expanded code
3150 -- The loop is rewritten as a block, to hold the element declaration
3152 New_Loop :=
3155 Handled_Statement_Sequence =>
3160 -- The element is only modified in expanded code, so it appears as
3161 -- unassigned to the warning machinery. We must suppress this spurious
3162 -- warning explicitly.
3168 -- The loop parameter is declared by an object declaration, but within
3169 -- the loop we must prevent user assignments to it, so we analyze the
3170 -- declaration and reset the entity kind, before analyzing the rest of
3171 -- the loop;
3179 -----------------------------
3180 -- Expand_N_Goto_Statement --
3181 -----------------------------
3183 -- Add poll before goto if polling active
3186 begin
3190 ---------------------------
3191 -- Expand_N_If_Statement --
3192 ---------------------------
3194 -- First we deal with the case of C and Fortran convention boolean values,
3195 -- with zero/non-zero semantics.
3197 -- Second, we deal with the obvious rewriting for the cases where the
3198 -- condition of the IF is known at compile time to be True or False.
3200 -- Third, we remove elsif parts which have non-empty Condition_Actions and
3201 -- rewrite as independent if statements. For example:
3203 -- if x then xs
3204 -- elsif y then ys
3205 -- ...
3206 -- end if;
3208 -- becomes
3209 --
3210 -- if x then xs
3211 -- else
3212 -- <<condition actions of y>>
3213 -- if y then ys
3214 -- ...
3215 -- end if;
3216 -- end if;
3218 -- This rewriting is needed if at least one elsif part has a non-empty
3219 -- Condition_Actions list. We also do the same processing if there is a
3220 -- constant condition in an elsif part (in conjunction with the first
3221 -- processing step mentioned above, for the recursive call made to deal
3222 -- with the created inner if, this deals with properly optimizing the
3223 -- cases of constant elsif conditions).
3233 -- Indicates whether we want warnings when we delete branches of the
3234 -- if statement based on constant condition analysis. We never want
3235 -- these warnings for expander generated code.
3237 begin
3238 -- Do not consider controlled objects found in an if statement which
3239 -- actually models an if expression because their early finalization
3240 -- will affect the result of the expression.
3248 -- The following loop deals with constant conditions for the IF. We
3249 -- need a loop because as we eliminate False conditions, we grab the
3250 -- first elsif condition and use it as the primary condition.
3254 -- If condition is True, we can simply rewrite the if statement now
3255 -- by replacing it by the series of then statements.
3259 -- All the else parts can be killed
3269 -- If condition is False, then we can delete the condition and
3270 -- the Then statements
3272 else
3273 -- We do not delete the condition if constant condition warnings
3274 -- are enabled, since otherwise we end up deleting the desired
3275 -- warning. Of course the backend will get rid of this True/False
3276 -- test anyway, so nothing is lost here.
3284 -- If there are no elsif statements, then we simply replace the
3285 -- entire if statement by the sequence of else statements.
3290 then
3293 else
3301 -- If there are elsif statements, the first of them becomes the
3302 -- if/then section of the rebuilt if statement This is the case
3303 -- where we loop to reprocess this copied condition.
3305 else
3311 -- Hed might have been captured as the condition determining
3312 -- the current value for an entity. Now it is detached from
3313 -- the tree, so a Current_Value pointer in the condition might
3314 -- need to be updated.
3325 -- Loop through elsif parts, dealing with constant conditions and
3326 -- possible condition actions that are present.
3332 -- Do not consider controlled objects found in an if statement
3333 -- which actually models an if expression because their early
3334 -- finalization will affect the result of the expression.
3342 -- If there are condition actions, then rewrite the if statement
3343 -- as indicated above. We also do the same rewrite for a True or
3344 -- False condition. The further processing of this constant
3345 -- condition is then done by the recursive call to expand the
3346 -- newly created if statement
3350 then
3351 New_If :=
3358 -- Elsif parts for new if come from remaining elsif's of parent
3382 -- Note this is not an implicit if statement, since it is part
3383 -- of an explicit if statement in the source (or of an implicit
3384 -- if statement that has already been tested). We set the flag
3385 -- after calling Analyze to avoid generating extra warnings
3386 -- specific to pure if statements, however (see
3387 -- Sem_Ch5.Analyze_If_Statement).
3392 -- No special processing for that elsif part, move to next
3394 else
3400 -- Some more optimizations applicable if we still have an IF statement
3406 -- Another optimization, special cases that can be simplified
3408 -- if expression then
3409 -- return true;
3410 -- else
3411 -- return false;
3412 -- end if;
3414 -- can be changed to:
3416 -- return expression;
3418 -- and
3420 -- if expression then
3421 -- return false;
3422 -- else
3423 -- return true;
3424 -- end if;
3426 -- can be changed to:
3428 -- return not (expression);
3430 -- Only do these optimizations if we are at least at -O1 level and
3431 -- do not do them if control flow optimizations are suppressed.
3435 then
3441 then
3442 declare
3446 begin
3448 and then
3450 then
3451 declare
3455 begin
3457 and then
3459 then
3462 then
3471 then
3474 Expression =>
3476 Right_Opnd =>
3489 --------------------------
3490 -- Expand_Iterator_Loop --
3491 --------------------------
3500 begin
3501 -- Processing for arrays
3510 else
3514 -- Processing for containers
3516 else
3517 Expand_Iterator_Loop_Over_Container
3522 -------------------------------------
3523 -- Expand_Iterator_Loop_Over_Array --
3524 -------------------------------------
3540 -- Start of processing for Expand_Iterator_Loop_Over_Array
3542 begin
3543 -- for Element of Array loop
3545 -- It requires an internally generated cursor to iterate over the array
3551 -- Generate:
3552 -- Element : Component_Type renames Array (Iterator);
3553 -- Iterator is the index value, or a list of index values
3554 -- in the case of a multidimensional array.
3556 Ind_Comp :=
3564 Subtype_Mark =>
3568 -- Mark the loop variable as needing debug info, so that expansion
3569 -- of the renaming will result in Materialize_Entity getting set via
3570 -- Debug_Renaming_Declaration. (This setting is needed here because
3571 -- the setting in Freeze_Entity comes after the expansion, which is
3572 -- too late. ???)
3576 -- Generate:
3578 -- for Iterator in [reverse] Array'Range (Array_Dim) loop
3579 -- Element : Component_Type renames Array (Iterator);
3580 -- <original loop statements>
3581 -- end loop;
3583 -- If this is an iteration over a multidimensional array, the
3584 -- innermost loop is over the last dimension in Ada, and over
3585 -- the first dimension in Fortran.
3589 else
3593 Core_Loop :=
3595 Iteration_Scheme =>
3597 Loop_Parameter_Specification =>
3600 Discrete_Subtype_Definition =>
3610 -- Processing for multidimensional array. The body of each loop is
3611 -- a loop over a previous dimension, going in decreasing order in Ada
3612 -- and in increasing order in Fortran.
3618 else
3624 -- Generate the dimension loops starting from the innermost one
3626 -- for Iterator in [reverse] Array'Range (Array_Dim - Dim) loop
3627 -- <core loop>
3628 -- end loop;
3630 Core_Loop :=
3632 Iteration_Scheme =>
3634 Loop_Parameter_Specification =>
3637 Discrete_Subtype_Definition =>
3647 -- Update the previously created object renaming declaration with
3648 -- the new iterator, by adding the index of the next loop to the
3649 -- indexed component, in the order that corresponds to the
3650 -- convention.
3655 else
3662 -- Inherit the loop identifier from the original loop. This ensures that
3663 -- the scope stack is consistent after the rewriting.
3673 -----------------------------------------
3674 -- Expand_Iterator_Loop_Over_Container --
3675 -----------------------------------------
3677 -- For a 'for ... in' loop, such as:
3679 -- for Cursor in Iterator_Function (...) loop
3680 -- ...
3681 -- end loop;
3683 -- we generate:
3685 -- Iter : Iterator_Type := Iterator_Function (...);
3686 -- Cursor : Cursor_type := First (Iter); -- or Last for "reverse"
3687 -- while Has_Element (Cursor) loop
3688 -- ...
3689 --
3690 -- Cursor := Iter.Next (Cursor); -- or Prev for "reverse"
3691 -- end loop;
3693 -- For a 'for ... of' loop, such as:
3695 -- for X of Container loop
3696 -- ...
3697 -- end loop;
3699 -- the RM implies the generation of:
3701 -- Iter : Iterator_Type := Container.Iterate; -- the Default_Iterator
3702 -- Cursor : Cursor_Type := First (Iter); -- or Last for "reverse"
3703 -- while Has_Element (Cursor) loop
3704 -- declare
3705 -- X : Element_Type renames Element (Cursor).Element.all;
3706 -- -- or Constant_Element
3707 -- begin
3708 -- ...
3709 -- end;
3710 -- Cursor := Iter.Next (Cursor); -- or Prev for "reverse"
3711 -- end loop;
3713 -- In the general case, we do what the RM says. However, the operations
3714 -- Element and Iter.Next are slow, which is bad inside a loop, because they
3715 -- involve dispatching via interfaces, secondary stack manipulation,
3716 -- Busy/Lock incr/decr, and adjust/finalization/at-end handling. So for the
3717 -- predefined containers, we use an equivalent but optimized expansion.
3719 -- In the optimized case, we make use of these:
3721 -- procedure Next (Position : in out Cursor); -- instead of Iter.Next
3723 -- function Pseudo_Reference
3724 -- (Container : aliased Vector'Class) return Reference_Control_Type;
3726 -- type Element_Access is access all Element_Type;
3728 -- function Get_Element_Access
3729 -- (Position : Cursor) return not null Element_Access;
3731 -- Next is declared in the visible part of the container packages.
3732 -- The other three are added in the private part. (We're not supposed to
3733 -- pollute the namespace for clients. The compiler has no trouble breaking
3734 -- privacy to call things in the private part of an instance.)
3736 -- Source:
3738 -- for X of My_Vector loop
3739 -- X.Count := X.Count + 1;
3740 -- ...
3741 -- end loop;
3743 -- The compiler will generate:
3745 -- Iter : Reversible_Iterator'Class := Iterate (My_Vector);
3746 -- -- Reversible_Iterator is an interface. Iterate is the
3747 -- -- Default_Iterator aspect of Vector. This increments Lock,
3748 -- -- disallowing tampering with cursors. Unfortunately, it does not
3749 -- -- increment Busy. The result of Iterate is Limited_Controlled;
3750 -- -- finalization will decrement Lock. This is a build-in-place
3751 -- -- dispatching call to Iterate.
3753 -- Cur : Cursor := First (Iter); -- or Last
3754 -- -- Dispatching call via interface.
3756 -- Control : Reference_Control_Type := Pseudo_Reference (My_Vector);
3757 -- -- Pseudo_Reference increments Busy, to detect tampering with
3758 -- -- elements, as required by RM. Also redundantly increment
3759 -- -- Lock. Finalization of Control will decrement both Busy and
3760 -- -- Lock. Pseudo_Reference returns a record containing a pointer to
3761 -- -- My_Vector, used by Finalize.
3762 -- --
3763 -- -- Control is not used below, except to finalize it -- it's purely
3764 -- -- an RAII thing. This is needed because we are eliminating the
3765 -- -- call to Reference within the loop.
3767 -- while Has_Element (Cur) loop
3768 -- declare
3769 -- X : My_Element renames Get_Element_Access (Cur).all;
3770 -- -- Get_Element_Access returns a pointer to the element
3771 -- -- designated by Cur. No dispatching here, and no horsing
3772 -- -- around with access discriminants. This is instead of the
3773 -- -- existing
3774 -- --
3775 -- -- X : My_Element renames Reference (Cur).Element.all;
3776 -- --
3777 -- -- which creates a controlled object.
3778 -- begin
3779 -- -- Any attempt to tamper with My_Vector here in the loop
3780 -- -- will correctly raise Program_Error, because of the
3781 -- -- Control.
3782 --
3783 -- X.Count := X.Count + 1;
3784 -- ...
3785 --
3786 -- Next (Cur); -- or Prev
3787 -- -- This is instead of "Cur := Next (Iter, Cur);"
3788 -- end;
3789 -- -- No finalization here
3790 -- end loop;
3791 -- Finalize Iter and Control here, decrementing Lock twice and Busy
3792 -- once.
3794 -- This optimization makes "for ... of" loops over 30 times faster in cases
3795 -- measured.
3797 procedure Expand_Iterator_Loop_Over_Container
3803 is
3820 -- Only for optimized version of "for ... of"
3823 -- The package in which the iterator interface is instantiated. This is
3824 -- typically an instance within the container package.
3827 -- The package in which the container type is declared
3829 begin
3830 -- Determine the advancement and initialization steps for the cursor.
3831 -- Analysis of the expanded loop will verify that the container has a
3832 -- reverse iterator.
3837 else
3842 -- The type of the iterator is the return type of the Iterate function
3843 -- used. For the "of" form this is the default iterator for the type,
3844 -- otherwise it is the type of the explicit function used in the
3845 -- iterator specification. The most common case will be an Iterate
3846 -- function in the container package.
3848 -- The Iterator type is declared in an instance within the container
3849 -- package itself, for example:
3851 -- package Vector_Iterator_Interfaces is new
3852 -- Ada.Iterator_Interfaces (Cursor, Has_Element);
3854 -- If the container type is a derived type, the cursor type is found in
3855 -- the package of the ultimate ancestor type.
3859 else
3867 function Get_Default_Iterator
3869 -- If the container is a derived type, the aspect holds the parent
3870 -- operation. The required one is a primitive of the derived type
3871 -- and is either inherited or overridden. Also sets Container_Arg.
3873 --------------------------
3874 -- Get_Default_Iterator --
3875 --------------------------
3877 function Get_Default_Iterator
3879 is
3885 begin
3888 -- A previous version of GNAT allowed indexing aspects to
3889 -- be redefined on derived container types, while the
3890 -- default iterator was inherited from the parent type.
3891 -- This non-standard extension is preserved temporarily for
3892 -- use by the modelling project under debug flag d.X.
3897 then
3898 Container_Arg :=
3900 Subtype_Mark =>
3901 New_Occurrence_Of
3910 -- The default iterator must be a primitive operation of the
3911 -- type, at the same dispatch slot position. The DT position
3912 -- may not be established if type is not frozen yet.
3919 or else
3923 then
3930 -- Default iterator must exist
3934 -- Otherwise not a derived type
3936 else
3941 -- Local variables
3949 -- Start of processing for Handle_Of
3951 begin
3953 Default_Iter :=
3955 else
3961 -- For a container element iterator, the iterator type is obtained
3962 -- from the corresponding aspect, whose return type is descended
3963 -- from the corresponding interface type in some instance of
3964 -- Ada.Iterator_Interfaces. The actuals of that instantiation
3965 -- are Cursor and Has_Element.
3969 -- The iterator type, which is a class-wide type, may itself be
3970 -- derived locally, so the desired instantiation is the scope of
3971 -- the root type of the iterator type.
3975 -- Find declarations needed for "for ... of" optimization
3984 then
3999 then
4003 Object_Definition =>
4005 Expression =>
4007 Name =>
4009 Parameter_Associations =>
4013 -- Rewrite domain of iteration as a call to the default iterator
4014 -- for the container type. The formal may be an access parameter
4015 -- in which case we must build a reference to the container.
4017 declare
4019 begin
4021 Arg :=
4025 else
4031 Name =>
4038 -- Find cursor type in proper iterator package, which is an
4039 -- instantiation of Iterator_Interfaces.
4052 Decl :=
4055 Subtype_Mark =>
4057 Name =>
4059 Prefix =>
4061 Name =>
4063 Parameter_Associations =>
4066 else
4067 Decl :=
4070 Subtype_Mark =>
4072 Name =>
4075 Expressions =>
4079 -- The defining identifier in the iterator is user-visible and
4080 -- must be visible in the debugger.
4084 -- If the container does not have a variable indexing aspect,
4085 -- the element is a constant in the loop. The container itself
4086 -- may be constant, in which case the element is a constant as
4087 -- well. The container has been rewritten as a call to Iterate,
4088 -- so examine original node.
4093 then
4100 -- X in Iterate (S) : type of iterator is type of explicitly given
4101 -- Iterate function, and the loop variable is the cursor. It will be
4102 -- assigned in the loop and must be a variable.
4104 else
4107 -- The iterator type, which is a class-wide type, may itself be
4108 -- derived locally, so the desired instantiation is the scope of
4109 -- the root type of the iterator type, as in the "of" case.
4117 -- For both iterator forms, add a call to the step operation to advance
4118 -- the cursor. Generate:
4120 -- Cursor := Iterator.Next (Cursor);
4122 -- or else
4124 -- Cursor := Next (Cursor);
4127 declare
4131 begin
4132 Step_Call :=
4134 Name =>
4142 else
4143 declare
4146 begin
4147 Rhs :=
4149 Name =>
4164 -- Generate:
4165 -- while Has_Element (Cursor) loop
4166 -- <Stats>
4167 -- end loop;
4169 -- Has_Element is the second actual in the iterator package
4171 New_Loop :=
4173 Iteration_Scheme =>
4175 Condition =>
4177 Name =>
4178 New_Occurrence_Of
4186 -- If present, preserve identifier of loop, which can be used in an exit
4187 -- statement in the body.
4193 -- Create the declarations for Iterator and cursor and insert them
4194 -- before the source loop. Given that the domain of iteration is already
4195 -- an entity, the iterator is just a renaming of that entity. Possible
4196 -- optimization ???
4204 -- Create declaration for cursor
4206 declare
4210 Object_Definition =>
4212 Expression =>
4214 Prefix =>
4216 Selector_Name =>
4219 begin
4220 -- The cursor is only modified in expanded code, so it appears
4221 -- as unassigned to the warning machinery. We must suppress this
4222 -- spurious warning explicitly. The cursor's kind is that of the
4223 -- original loop parameter (it is a constant if the domain of
4224 -- iteration is constant).
4233 -- If the range of iteration is given by a function call that returns
4234 -- a container, the finalization actions have been saved in the
4235 -- Condition_Actions of the iterator. Insert them now at the head of
4236 -- the loop.
4246 -----------------------------
4247 -- Expand_N_Loop_Statement --
4248 -----------------------------
4250 -- 1. Remove null loop entirely
4251 -- 2. Deal with while condition for C/Fortran boolean
4252 -- 3. Deal with loops with a non-standard enumeration type range
4253 -- 4. Deal with while loops where Condition_Actions is set
4254 -- 5. Deal with loops over predicated subtypes
4255 -- 6. Deal with loops with iterators over arrays and containers
4256 -- 7. Insert polling call if required
4263 begin
4264 -- Delete null loop
4271 -- Deal with condition for C/Fortran Boolean
4277 -- Generate polling call
4283 -- Nothing more to do for plain loop with no iteration scheme
4288 -- Case of for loop (Loop_Parameter_Specification present)
4290 -- Note: we do not have to worry about validity checking of the for loop
4291 -- range bounds here, since they were frozen with constant declarations
4292 -- and it is during that process that the validity checking is done.
4295 declare
4305 begin
4306 -- Deal with loop over predicates
4310 then
4313 -- Handle the case where we have a for loop with the range type
4314 -- being an enumeration type with non-standard representation.
4315 -- In this case we expand:
4317 -- for x in [reverse] a .. b loop
4318 -- ...
4319 -- end loop;
4321 -- to
4323 -- for xP in [reverse] integer
4324 -- range etype'Pos (a) .. etype'Pos (b)
4325 -- loop
4326 -- declare
4327 -- x : constant etype := Pos_To_Rep (xP);
4328 -- begin
4329 -- ...
4330 -- end;
4331 -- end loop;
4335 then
4336 New_Id :=
4340 -- If the type has a contiguous representation, successive
4341 -- values can be generated as offsets from the first literal.
4344 Expr :=
4347 Left_Opnd =>
4351 else
4352 -- Use the constructed array Enum_Pos_To_Rep
4354 Expr :=
4356 Prefix =>
4358 Expressions =>
4362 -- Build declaration for loop identifier
4364 Decls :=
4365 New_List (
4376 Iteration_Scheme =>
4378 Loop_Parameter_Specification =>
4383 Discrete_Subtype_Definition =>
4386 Subtype_Mark =>
4389 Constraint =>
4391 Range_Expression =>
4394 Low_Bound =>
4396 Prefix =>
4402 Relocate_Node
4405 High_Bound =>
4407 Prefix =>
4413 Relocate_Node
4414 (Type_High_Bound
4420 Handled_Statement_Sequence =>
4426 -- The loop parameter's entity must be removed from the loop
4427 -- scope's entity list and rendered invisible, since it will
4428 -- now be located in the new block scope. Any other entities
4429 -- already associated with the loop scope, such as the loop
4430 -- parameter's subtype, will remain there.
4432 -- In an element loop, the loop will contain a declaration for
4433 -- a cursor variable; otherwise the loop id is the first entity
4434 -- in the scope constructed for the loop.
4450 -- Nothing to do with other cases of for loops
4452 else
4457 -- Second case, if we have a while loop with Condition_Actions set, then
4458 -- we change it into a plain loop:
4460 -- while C loop
4461 -- ...
4462 -- end loop;
4464 -- changed to:
4466 -- loop
4467 -- <<condition actions>>
4468 -- exit when not C;
4469 -- ...
4470 -- end loop
4475 then
4476 declare
4479 begin
4480 ES :=
4482 Condition =>
4489 -- This is not an implicit loop, since it is generated in response
4490 -- to the loop statement being processed. If this is itself
4491 -- implicit, the restriction has already been checked. If not,
4492 -- it is an explicit loop.
4503 -- Here to deal with iterator case
4507 then
4510 -- An iterator loop may generate renaming declarations for elements
4511 -- that require debug information. This is the case in particular
4512 -- with element iterators, where debug information must be generated
4513 -- for the temporary that holds the element value. These temporaries
4514 -- are created within a transient block whose local declarations are
4515 -- transferred to the loop, which now has nontrivial local objects.
4519 then
4524 -- When the iteration scheme mentiones attribute 'Loop_Entry, the loop
4525 -- is transformed into a conditional block where the original loop is
4526 -- the sole statement. Inspect the statements of the nested loop for
4527 -- controlled objects.
4538 ----------------------------
4539 -- Expand_Predicated_Loop --
4540 ----------------------------
4542 -- Note: the expander can handle generation of loops over predicated
4543 -- subtypes for both the dynamic and static cases. Depending on what
4544 -- we decide is allowed in Ada 2012 mode and/or extensions allowed
4545 -- mode, the semantic analyzer may disallow one or both forms.
4556 begin
4557 -- Case of iteration over non-static predicate, should not be possible
4558 -- since this is not allowed by the semantics and should have been
4559 -- caught during analysis of the loop statement.
4564 -- If the predicate list is empty, that corresponds to a predicate of
4565 -- False, in which case the loop won't run at all, and we rewrite the
4566 -- entire loop as a null statement.
4572 -- For expansion over a static predicate we generate the following
4574 -- declare
4575 -- J : Ltype := min-val;
4576 -- begin
4577 -- loop
4578 -- body
4579 -- case J is
4580 -- when endpoint => J := startpoint;
4581 -- when endpoint => J := startpoint;
4582 -- ...
4583 -- when max-val => exit;
4584 -- when others => J := Lval'Succ (J);
4585 -- end case;
4586 -- end loop;
4587 -- end;
4589 -- with min-val replaced by max-val and Succ replaced by Pred if the
4590 -- loop parameter specification carries a Reverse indicator.
4592 -- To make this a little clearer, let's take a specific example:
4594 -- type Int is range 1 .. 10;
4595 -- subtype StaticP is Int with
4596 -- predicate => StaticP in 3 | 10 | 5 .. 7;
4597 -- ...
4598 -- for L in StaticP loop
4599 -- Put_Line ("static:" & J'Img);
4600 -- end loop;
4602 -- In this case, the loop is transformed into
4604 -- begin
4605 -- J : L := 3;
4606 -- loop
4607 -- body
4608 -- case J is
4609 -- when 3 => J := 5;
4610 -- when 7 => J := 10;
4611 -- when 10 => exit;
4612 -- when others => J := L'Succ (J);
4613 -- end case;
4614 -- end loop;
4615 -- end;
4617 else
4626 -- Given static expression or static range, returns an identifier
4627 -- whose value is the low bound of the expression value or range.
4630 -- Given static expression or static range, returns an identifier
4631 -- whose value is the high bound of the expression value or range.
4633 ------------
4634 -- Hi_Val --
4635 ------------
4638 begin
4641 else
4647 ------------
4648 -- Lo_Val --
4649 ------------
4652 begin
4655 else
4661 -- Start of processing for Static_Predicate
4663 begin
4664 -- Convert loop identifier to normal variable and reanalyze it so
4665 -- that this conversion works. We have to use the same defining
4666 -- identifier, since there may be references in the loop body.
4671 -- In most loops the loop variable is assigned in various
4672 -- alternatives in the body. However, in the rare case when
4673 -- the range specifies a single element, the loop variable
4674 -- may trigger a spurious warning that is could be constant.
4675 -- This warning might as well be suppressed.
4679 -- Loop to create branches of case statement
4685 -- Initial value is largest value in predicate.
4687 D :=
4697 else
4698 S :=
4713 else
4715 -- Initial value is smallest value in predicate.
4717 D :=
4727 else
4728 S :=
4744 -- Add others choice
4746 declare
4749 begin
4752 else
4756 S :=
4759 Expression =>
4773 -- Construct case statement and append to body statements
4775 Cstm :=
4781 -- Rewrite the loop
4788 Handled_Statement_Sequence =>
4800 ------------------------------
4801 -- Make_Tag_Ctrl_Assignment --
4802 ------------------------------
4815 and then not Comp_Asn
4822 begin
4823 -- Finalize the target of the assignment when controlled
4825 -- We have two exceptions here:
4827 -- 1. If we are in an init proc since it is an initialization more
4828 -- than an assignment.
4830 -- 2. If the left-hand side is a temporary that was not initialized
4831 -- (or the parent part of a temporary since it is the case in
4832 -- extension aggregates). Such a temporary does not come from
4833 -- source. We must examine the original node for the prefix, because
4834 -- it may be a component of an entry formal, in which case it has
4835 -- been rewritten and does not appear to come from source either.
4837 -- Case of init proc
4842 -- The left-hand side is an uninitialized temporary object
4847 N_Object_Declaration
4849 then
4852 else
4853 Fin_Call :=
4854 Make_Final_Call
4863 -- Save the Tag in a local variable Tag_Id
4872 Expression =>
4875 Selector_Name =>
4878 -- Otherwise Tag_Id is not used
4880 else
4884 -- If the tagged type has a full rep clause, expand the assignment into
4885 -- component-wise assignments. Mark the node as unanalyzed in order to
4886 -- generate the proper code and propagate this scenario by setting a
4887 -- flag to avoid infinite recursion.
4896 -- Restore the tag
4901 Name =>
4904 Selector_Name =>
4909 -- Adjust the target after the assignment when controlled (not in the
4910 -- init proc since it is an initialization more than an assignment).
4913 Adj_Call :=
4914 Make_Adjust_Call
4925 exception
4927 -- Could use comment here ???