1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2010, Free Software Foundation, Inc. --
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. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Checks; use Checks;
28 with Debug; use Debug;
29 with Einfo; use Einfo;
30 with Elists; use Elists;
31 with Exp_Atag; use Exp_Atag;
32 with Exp_Aggr; use Exp_Aggr;
33 with Exp_Ch6; use Exp_Ch6;
34 with Exp_Ch7; use Exp_Ch7;
35 with Exp_Ch11; use Exp_Ch11;
36 with Exp_Dbug; use Exp_Dbug;
37 with Exp_Pakd; use Exp_Pakd;
38 with Exp_Tss; use Exp_Tss;
39 with Exp_Util; use Exp_Util;
40 with Namet; use Namet;
41 with Nlists; use Nlists;
42 with Nmake; use Nmake;
44 with Restrict; use Restrict;
45 with Rident; use Rident;
46 with Rtsfind; use Rtsfind;
47 with Sinfo; use Sinfo;
49 with Sem_Aux; use Sem_Aux;
50 with Sem_Ch3; use Sem_Ch3;
51 with Sem_Ch8; use Sem_Ch8;
52 with Sem_Ch13; use Sem_Ch13;
53 with Sem_Eval; use Sem_Eval;
54 with Sem_Res; use Sem_Res;
55 with Sem_Util; use Sem_Util;
56 with Snames; use Snames;
57 with Stand; use Stand;
58 with Stringt; use Stringt;
59 with Targparm; use Targparm;
60 with Tbuild; use Tbuild;
61 with Ttypes; use Ttypes;
62 with Uintp; use Uintp;
63 with Validsw; use Validsw;
65 package body Exp_Ch5 is
67 function Change_Of_Representation (N : Node_Id) return Boolean;
68 -- Determine if the right hand side of the assignment N is a type
69 -- conversion which requires a change of representation. Called
70 -- only for the array and record cases.
72 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id);
73 -- N is an assignment which assigns an array value. This routine process
74 -- the various special cases and checks required for such assignments,
75 -- including change of representation. Rhs is normally simply the right
76 -- hand side of the assignment, except that if the right hand side is
77 -- a type conversion or a qualified expression, then the Rhs is the
78 -- actual expression inside any such type conversions or qualifications.
80 function Expand_Assign_Array_Loop
87 Rev : Boolean) return Node_Id;
88 -- N is an assignment statement which assigns an array value. This routine
89 -- expands the assignment into a loop (or nested loops for the case of a
90 -- multi-dimensional array) to do the assignment component by component.
91 -- Larray and Rarray are the entities of the actual arrays on the left
92 -- hand and right hand sides. L_Type and R_Type are the types of these
93 -- arrays (which may not be the same, due to either sliding, or to a
94 -- change of representation case). Ndim is the number of dimensions and
95 -- the parameter Rev indicates if the loops run normally (Rev = False),
96 -- or reversed (Rev = True). The value returned is the constructed
97 -- loop statement. Auxiliary declarations are inserted before node N
98 -- using the standard Insert_Actions mechanism.
100 procedure Expand_Assign_Record (N : Node_Id);
101 -- N is an assignment of a non-tagged record value. This routine handles
102 -- the case where the assignment must be made component by component,
103 -- either because the target is not byte aligned, or there is a change
104 -- of representation, or when we have a tagged type with a representation
105 -- clause (this last case is required because holes in the tagged type
106 -- might be filled with components from child types).
108 procedure Expand_Non_Function_Return (N : Node_Id);
109 -- Called by Expand_N_Simple_Return_Statement in case we're returning from
110 -- a procedure body, entry body, accept statement, or extended return
111 -- statement. Note that all non-function returns are simple return
114 procedure Expand_Simple_Function_Return (N : Node_Id);
115 -- Expand simple return from function. In the case where we are returning
116 -- from a function body this is called by Expand_N_Simple_Return_Statement.
118 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
119 -- Generate the necessary code for controlled and tagged assignment, that
120 -- is to say, finalization of the target before, adjustment of the target
121 -- after and save and restore of the tag and finalization pointers which
122 -- are not 'part of the value' and must not be changed upon assignment. N
123 -- is the original Assignment node.
125 ------------------------------
126 -- Change_Of_Representation --
127 ------------------------------
129 function Change_Of_Representation (N : Node_Id) return Boolean is
130 Rhs : constant Node_Id := Expression (N);
133 Nkind (Rhs) = N_Type_Conversion
135 not Same_Representation (Etype (Rhs), Etype (Expression (Rhs)));
136 end Change_Of_Representation;
138 -------------------------
139 -- Expand_Assign_Array --
140 -------------------------
142 -- There are two issues here. First, do we let Gigi do a block move, or
143 -- do we expand out into a loop? Second, we need to set the two flags
144 -- Forwards_OK and Backwards_OK which show whether the block move (or
145 -- corresponding loops) can be legitimately done in a forwards (low to
146 -- high) or backwards (high to low) manner.
148 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is
149 Loc : constant Source_Ptr := Sloc (N);
151 Lhs : constant Node_Id := Name (N);
153 Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs);
154 Act_Rhs : Node_Id := Get_Referenced_Object (Rhs);
156 L_Type : constant Entity_Id :=
157 Underlying_Type (Get_Actual_Subtype (Act_Lhs));
158 R_Type : Entity_Id :=
159 Underlying_Type (Get_Actual_Subtype (Act_Rhs));
161 L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice;
162 R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice;
164 Crep : constant Boolean := Change_Of_Representation (N);
169 Ndim : constant Pos := Number_Dimensions (L_Type);
171 Loop_Required : Boolean := False;
172 -- This switch is set to True if the array move must be done using
173 -- an explicit front end generated loop.
175 procedure Apply_Dereference (Arg : Node_Id);
176 -- If the argument is an access to an array, and the assignment is
177 -- converted into a procedure call, apply explicit dereference.
179 function Has_Address_Clause (Exp : Node_Id) return Boolean;
180 -- Test if Exp is a reference to an array whose declaration has
181 -- an address clause, or it is a slice of such an array.
183 function Is_Formal_Array (Exp : Node_Id) return Boolean;
184 -- Test if Exp is a reference to an array which is either a formal
185 -- parameter or a slice of a formal parameter. These are the cases
186 -- where hidden aliasing can occur.
188 function Is_Non_Local_Array (Exp : Node_Id) return Boolean;
189 -- Determine if Exp is a reference to an array variable which is other
190 -- than an object defined in the current scope, or a slice of such
191 -- an object. Such objects can be aliased to parameters (unlike local
192 -- array references).
194 -----------------------
195 -- Apply_Dereference --
196 -----------------------
198 procedure Apply_Dereference (Arg : Node_Id) is
199 Typ : constant Entity_Id := Etype (Arg);
201 if Is_Access_Type (Typ) then
202 Rewrite (Arg, Make_Explicit_Dereference (Loc,
203 Prefix => Relocate_Node (Arg)));
204 Analyze_And_Resolve (Arg, Designated_Type (Typ));
206 end Apply_Dereference;
208 ------------------------
209 -- Has_Address_Clause --
210 ------------------------
212 function Has_Address_Clause (Exp : Node_Id) return Boolean is
215 (Is_Entity_Name (Exp) and then
216 Present (Address_Clause (Entity (Exp))))
218 (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp)));
219 end Has_Address_Clause;
221 ---------------------
222 -- Is_Formal_Array --
223 ---------------------
225 function Is_Formal_Array (Exp : Node_Id) return Boolean is
228 (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp)))
230 (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp)));
233 ------------------------
234 -- Is_Non_Local_Array --
235 ------------------------
237 function Is_Non_Local_Array (Exp : Node_Id) return Boolean is
239 return (Is_Entity_Name (Exp)
240 and then Scope (Entity (Exp)) /= Current_Scope)
241 or else (Nkind (Exp) = N_Slice
242 and then Is_Non_Local_Array (Prefix (Exp)));
243 end Is_Non_Local_Array;
245 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
247 Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs);
248 Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs);
250 Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs);
251 Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs);
253 -- Start of processing for Expand_Assign_Array
256 -- Deal with length check. Note that the length check is done with
257 -- respect to the right hand side as given, not a possible underlying
258 -- renamed object, since this would generate incorrect extra checks.
260 Apply_Length_Check (Rhs, L_Type);
262 -- We start by assuming that the move can be done in either direction,
263 -- i.e. that the two sides are completely disjoint.
265 Set_Forwards_OK (N, True);
266 Set_Backwards_OK (N, True);
268 -- Normally it is only the slice case that can lead to overlap, and
269 -- explicit checks for slices are made below. But there is one case
270 -- where the slice can be implicit and invisible to us: when we have a
271 -- one dimensional array, and either both operands are parameters, or
272 -- one is a parameter (which can be a slice passed by reference) and the
273 -- other is a non-local variable. In this case the parameter could be a
274 -- slice that overlaps with the other operand.
276 -- However, if the array subtype is a constrained first subtype in the
277 -- parameter case, then we don't have to worry about overlap, since
278 -- slice assignments aren't possible (other than for a slice denoting
281 -- Note: No overlap is possible if there is a change of representation,
282 -- so we can exclude this case.
287 ((Lhs_Formal and Rhs_Formal)
289 (Lhs_Formal and Rhs_Non_Local_Var)
291 (Rhs_Formal and Lhs_Non_Local_Var))
293 (not Is_Constrained (Etype (Lhs))
294 or else not Is_First_Subtype (Etype (Lhs)))
296 -- In the case of compiling for the Java or .NET Virtual Machine,
297 -- slices are always passed by making a copy, so we don't have to
298 -- worry about overlap. We also want to prevent generation of "<"
299 -- comparisons for array addresses, since that's a meaningless
300 -- operation on the VM.
302 and then VM_Target = No_VM
304 Set_Forwards_OK (N, False);
305 Set_Backwards_OK (N, False);
307 -- Note: the bit-packed case is not worrisome here, since if we have
308 -- a slice passed as a parameter, it is always aligned on a byte
309 -- boundary, and if there are no explicit slices, the assignment
310 -- can be performed directly.
313 -- If either operand has an address clause clear Backwards_OK and
314 -- Forwards_OK, since we cannot tell if the operands overlap. We
315 -- exclude this treatment when Rhs is an aggregate, since we know
316 -- that overlap can't occur.
318 if (Has_Address_Clause (Lhs) and then Nkind (Rhs) /= N_Aggregate)
319 or else Has_Address_Clause (Rhs)
321 Set_Forwards_OK (N, False);
322 Set_Backwards_OK (N, False);
325 -- We certainly must use a loop for change of representation and also
326 -- we use the operand of the conversion on the right hand side as the
327 -- effective right hand side (the component types must match in this
331 Act_Rhs := Get_Referenced_Object (Rhs);
332 R_Type := Get_Actual_Subtype (Act_Rhs);
333 Loop_Required := True;
335 -- We require a loop if the left side is possibly bit unaligned
337 elsif Possible_Bit_Aligned_Component (Lhs)
339 Possible_Bit_Aligned_Component (Rhs)
341 Loop_Required := True;
343 -- Arrays with controlled components are expanded into a loop to force
344 -- calls to Adjust at the component level.
346 elsif Has_Controlled_Component (L_Type) then
347 Loop_Required := True;
349 -- If object is atomic, we cannot tolerate a loop
351 elsif Is_Atomic_Object (Act_Lhs)
353 Is_Atomic_Object (Act_Rhs)
357 -- Loop is required if we have atomic components since we have to
358 -- be sure to do any accesses on an element by element basis.
360 elsif Has_Atomic_Components (L_Type)
361 or else Has_Atomic_Components (R_Type)
362 or else Is_Atomic (Component_Type (L_Type))
363 or else Is_Atomic (Component_Type (R_Type))
365 Loop_Required := True;
367 -- Case where no slice is involved
369 elsif not L_Slice and not R_Slice then
371 -- The following code deals with the case of unconstrained bit packed
372 -- arrays. The problem is that the template for such arrays contains
373 -- the bounds of the actual source level array, but the copy of an
374 -- entire array requires the bounds of the underlying array. It would
375 -- be nice if the back end could take care of this, but right now it
376 -- does not know how, so if we have such a type, then we expand out
377 -- into a loop, which is inefficient but works correctly. If we don't
378 -- do this, we get the wrong length computed for the array to be
379 -- moved. The two cases we need to worry about are:
381 -- Explicit dereference of an unconstrained packed array type as in
382 -- the following example:
385 -- type BITS is array(INTEGER range <>) of BOOLEAN;
386 -- pragma PACK(BITS);
387 -- type A is access BITS;
390 -- P1 := new BITS (1 .. 65_535);
391 -- P2 := new BITS (1 .. 65_535);
395 -- A formal parameter reference with an unconstrained bit array type
396 -- is the other case we need to worry about (here we assume the same
397 -- BITS type declared above):
399 -- procedure Write_All (File : out BITS; Contents : BITS);
401 -- File.Storage := Contents;
404 -- We expand to a loop in either of these two cases
406 -- Question for future thought. Another potentially more efficient
407 -- approach would be to create the actual subtype, and then do an
408 -- unchecked conversion to this actual subtype ???
410 Check_Unconstrained_Bit_Packed_Array : declare
412 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean;
413 -- Function to perform required test for the first case, above
414 -- (dereference of an unconstrained bit packed array).
416 -----------------------
417 -- Is_UBPA_Reference --
418 -----------------------
420 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is
421 Typ : constant Entity_Id := Underlying_Type (Etype (Opnd));
423 Des_Type : Entity_Id;
426 if Present (Packed_Array_Type (Typ))
427 and then Is_Array_Type (Packed_Array_Type (Typ))
428 and then not Is_Constrained (Packed_Array_Type (Typ))
432 elsif Nkind (Opnd) = N_Explicit_Dereference then
433 P_Type := Underlying_Type (Etype (Prefix (Opnd)));
435 if not Is_Access_Type (P_Type) then
439 Des_Type := Designated_Type (P_Type);
441 Is_Bit_Packed_Array (Des_Type)
442 and then not Is_Constrained (Des_Type);
448 end Is_UBPA_Reference;
450 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
453 if Is_UBPA_Reference (Lhs)
455 Is_UBPA_Reference (Rhs)
457 Loop_Required := True;
459 -- Here if we do not have the case of a reference to a bit packed
460 -- unconstrained array case. In this case gigi can most certainly
461 -- handle the assignment if a forwards move is allowed.
463 -- (could it handle the backwards case also???)
465 elsif Forwards_OK (N) then
468 end Check_Unconstrained_Bit_Packed_Array;
470 -- The back end can always handle the assignment if the right side is a
471 -- string literal (note that overlap is definitely impossible in this
472 -- case). If the type is packed, a string literal is always converted
473 -- into an aggregate, except in the case of a null slice, for which no
474 -- aggregate can be written. In that case, rewrite the assignment as a
475 -- null statement, a length check has already been emitted to verify
476 -- that the range of the left-hand side is empty.
478 -- Note that this code is not executed if we have an assignment of a
479 -- string literal to a non-bit aligned component of a record, a case
480 -- which cannot be handled by the backend.
482 elsif Nkind (Rhs) = N_String_Literal then
483 if String_Length (Strval (Rhs)) = 0
484 and then Is_Bit_Packed_Array (L_Type)
486 Rewrite (N, Make_Null_Statement (Loc));
492 -- If either operand is bit packed, then we need a loop, since we can't
493 -- be sure that the slice is byte aligned. Similarly, if either operand
494 -- is a possibly unaligned slice, then we need a loop (since the back
495 -- end cannot handle unaligned slices).
497 elsif Is_Bit_Packed_Array (L_Type)
498 or else Is_Bit_Packed_Array (R_Type)
499 or else Is_Possibly_Unaligned_Slice (Lhs)
500 or else Is_Possibly_Unaligned_Slice (Rhs)
502 Loop_Required := True;
504 -- If we are not bit-packed, and we have only one slice, then no overlap
505 -- is possible except in the parameter case, so we can let the back end
508 elsif not (L_Slice and R_Slice) then
509 if Forwards_OK (N) then
514 -- If the right-hand side is a string literal, introduce a temporary for
515 -- it, for use in the generated loop that will follow.
517 if Nkind (Rhs) = N_String_Literal then
519 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Rhs);
524 Make_Object_Declaration (Loc,
525 Defining_Identifier => Temp,
526 Object_Definition => New_Occurrence_Of (L_Type, Loc),
527 Expression => Relocate_Node (Rhs));
529 Insert_Action (N, Decl);
530 Rewrite (Rhs, New_Occurrence_Of (Temp, Loc));
531 R_Type := Etype (Temp);
535 -- Come here to complete the analysis
537 -- Loop_Required: Set to True if we know that a loop is required
538 -- regardless of overlap considerations.
540 -- Forwards_OK: Set to False if we already know that a forwards
541 -- move is not safe, else set to True.
543 -- Backwards_OK: Set to False if we already know that a backwards
544 -- move is not safe, else set to True
546 -- Our task at this stage is to complete the overlap analysis, which can
547 -- result in possibly setting Forwards_OK or Backwards_OK to False, and
548 -- then generating the final code, either by deciding that it is OK
549 -- after all to let Gigi handle it, or by generating appropriate code
553 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
554 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type));
556 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ);
557 Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ);
558 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ);
559 Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ);
561 Act_L_Array : Node_Id;
562 Act_R_Array : Node_Id;
568 Cresult : Compare_Result;
571 -- Get the expressions for the arrays. If we are dealing with a
572 -- private type, then convert to the underlying type. We can do
573 -- direct assignments to an array that is a private type, but we
574 -- cannot assign to elements of the array without this extra
575 -- unchecked conversion.
577 if Nkind (Act_Lhs) = N_Slice then
578 Larray := Prefix (Act_Lhs);
582 if Is_Private_Type (Etype (Larray)) then
585 (Underlying_Type (Etype (Larray)), Larray);
589 if Nkind (Act_Rhs) = N_Slice then
590 Rarray := Prefix (Act_Rhs);
594 if Is_Private_Type (Etype (Rarray)) then
597 (Underlying_Type (Etype (Rarray)), Rarray);
601 -- If both sides are slices, we must figure out whether it is safe
602 -- to do the move in one direction or the other. It is always safe
603 -- if there is a change of representation since obviously two arrays
604 -- with different representations cannot possibly overlap.
606 if (not Crep) and L_Slice and R_Slice then
607 Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
608 Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
610 -- If both left and right hand arrays are entity names, and refer
611 -- to different entities, then we know that the move is safe (the
612 -- two storage areas are completely disjoint).
614 if Is_Entity_Name (Act_L_Array)
615 and then Is_Entity_Name (Act_R_Array)
616 and then Entity (Act_L_Array) /= Entity (Act_R_Array)
620 -- Otherwise, we assume the worst, which is that the two arrays
621 -- are the same array. There is no need to check if we know that
622 -- is the case, because if we don't know it, we still have to
625 -- Generally if the same array is involved, then we have an
626 -- overlapping case. We will have to really assume the worst (i.e.
627 -- set neither of the OK flags) unless we can determine the lower
628 -- or upper bounds at compile time and compare them.
633 (Left_Lo, Right_Lo, Assume_Valid => True);
635 if Cresult = Unknown then
638 (Left_Hi, Right_Hi, Assume_Valid => True);
642 when LT | LE | EQ => Set_Backwards_OK (N, False);
643 when GT | GE => Set_Forwards_OK (N, False);
644 when NE | Unknown => Set_Backwards_OK (N, False);
645 Set_Forwards_OK (N, False);
650 -- If after that analysis Loop_Required is False, meaning that we
651 -- have not discovered some non-overlap reason for requiring a loop,
652 -- then the outcome depends on the capabilities of the back end.
654 if not Loop_Required then
656 -- The GCC back end can deal with all cases of overlap by falling
657 -- back to memmove if it cannot use a more efficient approach.
659 if VM_Target = No_VM and not AAMP_On_Target then
662 -- Assume other back ends can handle it if Forwards_OK is set
664 elsif Forwards_OK (N) then
667 -- If Forwards_OK is not set, the back end will need something
668 -- like memmove to handle the move. For now, this processing is
669 -- activated using the .s debug flag (-gnatd.s).
671 elsif Debug_Flag_Dot_S then
676 -- At this stage we have to generate an explicit loop, and we have
677 -- the following cases:
679 -- Forwards_OK = True
681 -- Rnn : right_index := right_index'First;
682 -- for Lnn in left-index loop
683 -- left (Lnn) := right (Rnn);
684 -- Rnn := right_index'Succ (Rnn);
687 -- Note: the above code MUST be analyzed with checks off, because
688 -- otherwise the Succ could overflow. But in any case this is more
691 -- Forwards_OK = False, Backwards_OK = True
693 -- Rnn : right_index := right_index'Last;
694 -- for Lnn in reverse left-index loop
695 -- left (Lnn) := right (Rnn);
696 -- Rnn := right_index'Pred (Rnn);
699 -- Note: the above code MUST be analyzed with checks off, because
700 -- otherwise the Pred could overflow. But in any case this is more
703 -- Forwards_OK = Backwards_OK = False
705 -- This only happens if we have the same array on each side. It is
706 -- possible to create situations using overlays that violate this,
707 -- but we simply do not promise to get this "right" in this case.
709 -- There are two possible subcases. If the No_Implicit_Conditionals
710 -- restriction is set, then we generate the following code:
713 -- T : constant <operand-type> := rhs;
718 -- If implicit conditionals are permitted, then we generate:
720 -- if Left_Lo <= Right_Lo then
721 -- <code for Forwards_OK = True above>
723 -- <code for Backwards_OK = True above>
726 -- In order to detect possible aliasing, we examine the renamed
727 -- expression when the source or target is a renaming. However,
728 -- the renaming may be intended to capture an address that may be
729 -- affected by subsequent code, and therefore we must recover
730 -- the actual entity for the expansion that follows, not the
731 -- object it renames. In particular, if source or target designate
732 -- a portion of a dynamically allocated object, the pointer to it
733 -- may be reassigned but the renaming preserves the proper location.
735 if Is_Entity_Name (Rhs)
737 Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration
738 and then Nkind (Act_Rhs) = N_Slice
743 if Is_Entity_Name (Lhs)
745 Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration
746 and then Nkind (Act_Lhs) = N_Slice
751 -- Cases where either Forwards_OK or Backwards_OK is true
753 if Forwards_OK (N) or else Backwards_OK (N) then
754 if Needs_Finalization (Component_Type (L_Type))
755 and then Base_Type (L_Type) = Base_Type (R_Type)
757 and then not No_Ctrl_Actions (N)
760 Proc : constant Entity_Id :=
761 TSS (Base_Type (L_Type), TSS_Slice_Assign);
765 Apply_Dereference (Larray);
766 Apply_Dereference (Rarray);
767 Actuals := New_List (
768 Duplicate_Subexpr (Larray, Name_Req => True),
769 Duplicate_Subexpr (Rarray, Name_Req => True),
770 Duplicate_Subexpr (Left_Lo, Name_Req => True),
771 Duplicate_Subexpr (Left_Hi, Name_Req => True),
772 Duplicate_Subexpr (Right_Lo, Name_Req => True),
773 Duplicate_Subexpr (Right_Hi, Name_Req => True));
777 Boolean_Literals (not Forwards_OK (N)), Loc));
780 Make_Procedure_Call_Statement (Loc,
781 Name => New_Reference_To (Proc, Loc),
782 Parameter_Associations => Actuals));
787 Expand_Assign_Array_Loop
788 (N, Larray, Rarray, L_Type, R_Type, Ndim,
789 Rev => not Forwards_OK (N)));
792 -- Case of both are false with No_Implicit_Conditionals
794 elsif Restriction_Active (No_Implicit_Conditionals) then
796 T : constant Entity_Id :=
797 Make_Defining_Identifier (Loc, Chars => Name_T);
801 Make_Block_Statement (Loc,
802 Declarations => New_List (
803 Make_Object_Declaration (Loc,
804 Defining_Identifier => T,
805 Constant_Present => True,
807 New_Occurrence_Of (Etype (Rhs), Loc),
808 Expression => Relocate_Node (Rhs))),
810 Handled_Statement_Sequence =>
811 Make_Handled_Sequence_Of_Statements (Loc,
812 Statements => New_List (
813 Make_Assignment_Statement (Loc,
814 Name => Relocate_Node (Lhs),
815 Expression => New_Occurrence_Of (T, Loc))))));
818 -- Case of both are false with implicit conditionals allowed
821 -- Before we generate this code, we must ensure that the left and
822 -- right side array types are defined. They may be itypes, and we
823 -- cannot let them be defined inside the if, since the first use
824 -- in the then may not be executed.
826 Ensure_Defined (L_Type, N);
827 Ensure_Defined (R_Type, N);
829 -- We normally compare addresses to find out which way round to
830 -- do the loop, since this is reliable, and handles the cases of
831 -- parameters, conversions etc. But we can't do that in the bit
832 -- packed case or the VM case, because addresses don't work there.
834 if not Is_Bit_Packed_Array (L_Type) and then VM_Target = No_VM then
838 Unchecked_Convert_To (RTE (RE_Integer_Address),
839 Make_Attribute_Reference (Loc,
841 Make_Indexed_Component (Loc,
843 Duplicate_Subexpr_Move_Checks (Larray, True),
844 Expressions => New_List (
845 Make_Attribute_Reference (Loc,
849 Attribute_Name => Name_First))),
850 Attribute_Name => Name_Address)),
853 Unchecked_Convert_To (RTE (RE_Integer_Address),
854 Make_Attribute_Reference (Loc,
856 Make_Indexed_Component (Loc,
858 Duplicate_Subexpr_Move_Checks (Rarray, True),
859 Expressions => New_List (
860 Make_Attribute_Reference (Loc,
864 Attribute_Name => Name_First))),
865 Attribute_Name => Name_Address)));
867 -- For the bit packed and VM cases we use the bounds. That's OK,
868 -- because we don't have to worry about parameters, since they
869 -- cannot cause overlap. Perhaps we should worry about weird slice
875 Cleft_Lo := New_Copy_Tree (Left_Lo);
876 Cright_Lo := New_Copy_Tree (Right_Lo);
878 -- If the types do not match we add an implicit conversion
879 -- here to ensure proper match
881 if Etype (Left_Lo) /= Etype (Right_Lo) then
883 Unchecked_Convert_To (Etype (Left_Lo), Cright_Lo);
886 -- Reset the Analyzed flag, because the bounds of the index
887 -- type itself may be universal, and must must be reaanalyzed
888 -- to acquire the proper type for the back end.
890 Set_Analyzed (Cleft_Lo, False);
891 Set_Analyzed (Cright_Lo, False);
895 Left_Opnd => Cleft_Lo,
896 Right_Opnd => Cright_Lo);
899 if Needs_Finalization (Component_Type (L_Type))
900 and then Base_Type (L_Type) = Base_Type (R_Type)
902 and then not No_Ctrl_Actions (N)
905 -- Call TSS procedure for array assignment, passing the
906 -- explicit bounds of right and left hand sides.
909 Proc : constant Entity_Id :=
910 TSS (Base_Type (L_Type), TSS_Slice_Assign);
914 Apply_Dereference (Larray);
915 Apply_Dereference (Rarray);
916 Actuals := New_List (
917 Duplicate_Subexpr (Larray, Name_Req => True),
918 Duplicate_Subexpr (Rarray, Name_Req => True),
919 Duplicate_Subexpr (Left_Lo, Name_Req => True),
920 Duplicate_Subexpr (Left_Hi, Name_Req => True),
921 Duplicate_Subexpr (Right_Lo, Name_Req => True),
922 Duplicate_Subexpr (Right_Hi, Name_Req => True));
926 Right_Opnd => Condition));
929 Make_Procedure_Call_Statement (Loc,
930 Name => New_Reference_To (Proc, Loc),
931 Parameter_Associations => Actuals));
936 Make_Implicit_If_Statement (N,
937 Condition => Condition,
939 Then_Statements => New_List (
940 Expand_Assign_Array_Loop
941 (N, Larray, Rarray, L_Type, R_Type, Ndim,
944 Else_Statements => New_List (
945 Expand_Assign_Array_Loop
946 (N, Larray, Rarray, L_Type, R_Type, Ndim,
951 Analyze (N, Suppress => All_Checks);
955 when RE_Not_Available =>
957 end Expand_Assign_Array;
959 ------------------------------
960 -- Expand_Assign_Array_Loop --
961 ------------------------------
963 -- The following is an example of the loop generated for the case of a
964 -- two-dimensional array:
969 -- for L1b in 1 .. 100 loop
973 -- for L3b in 1 .. 100 loop
974 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
975 -- R4b := Tm1X2'succ(R4b);
978 -- R2b := Tm1X1'succ(R2b);
982 -- Here Rev is False, and Tm1Xn are the subscript types for the right hand
983 -- side. The declarations of R2b and R4b are inserted before the original
984 -- assignment statement.
986 function Expand_Assign_Array_Loop
993 Rev : Boolean) return Node_Id
995 Loc : constant Source_Ptr := Sloc (N);
997 Lnn : array (1 .. Ndim) of Entity_Id;
998 Rnn : array (1 .. Ndim) of Entity_Id;
999 -- Entities used as subscripts on left and right sides
1001 L_Index_Type : array (1 .. Ndim) of Entity_Id;
1002 R_Index_Type : array (1 .. Ndim) of Entity_Id;
1003 -- Left and right index types
1010 function Build_Step (J : Nat) return Node_Id;
1011 -- The increment step for the index of the right-hand side is written
1012 -- as an attribute reference (Succ or Pred). This function returns
1013 -- the corresponding node, which is placed at the end of the loop body.
1019 function Build_Step (J : Nat) return Node_Id is
1031 Make_Assignment_Statement (Loc,
1032 Name => New_Occurrence_Of (Rnn (J), Loc),
1034 Make_Attribute_Reference (Loc,
1036 New_Occurrence_Of (R_Index_Type (J), Loc),
1037 Attribute_Name => S_Or_P,
1038 Expressions => New_List (
1039 New_Occurrence_Of (Rnn (J), Loc))));
1041 -- Note that on the last iteration of the loop, the index is increased
1042 -- (or decreased) past the corresponding bound. This is consistent with
1043 -- the C semantics of the back-end, where such an off-by-one value on a
1044 -- dead index variable is OK. However, in CodePeer mode this leads to
1045 -- spurious warnings, and thus we place a guard around the attribute
1046 -- reference. For obvious reasons we only do this for CodePeer.
1048 if CodePeer_Mode then
1050 Make_If_Statement (Loc,
1053 Left_Opnd => New_Occurrence_Of (Lnn (J), Loc),
1055 Make_Attribute_Reference (Loc,
1056 Prefix => New_Occurrence_Of (L_Index_Type (J), Loc),
1057 Attribute_Name => Lim)),
1058 Then_Statements => New_List (Step));
1066 F_Or_L := Name_Last;
1067 S_Or_P := Name_Pred;
1069 F_Or_L := Name_First;
1070 S_Or_P := Name_Succ;
1073 -- Setup index types and subscript entities
1080 L_Index := First_Index (L_Type);
1081 R_Index := First_Index (R_Type);
1083 for J in 1 .. Ndim loop
1084 Lnn (J) := Make_Temporary (Loc, 'L');
1085 Rnn (J) := Make_Temporary (Loc, 'R');
1087 L_Index_Type (J) := Etype (L_Index);
1088 R_Index_Type (J) := Etype (R_Index);
1090 Next_Index (L_Index);
1091 Next_Index (R_Index);
1095 -- Now construct the assignment statement
1098 ExprL : constant List_Id := New_List;
1099 ExprR : constant List_Id := New_List;
1102 for J in 1 .. Ndim loop
1103 Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc));
1104 Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc));
1108 Make_Assignment_Statement (Loc,
1110 Make_Indexed_Component (Loc,
1111 Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
1112 Expressions => ExprL),
1114 Make_Indexed_Component (Loc,
1115 Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
1116 Expressions => ExprR));
1118 -- We set assignment OK, since there are some cases, e.g. in object
1119 -- declarations, where we are actually assigning into a constant.
1120 -- If there really is an illegality, it was caught long before now,
1121 -- and was flagged when the original assignment was analyzed.
1123 Set_Assignment_OK (Name (Assign));
1125 -- Propagate the No_Ctrl_Actions flag to individual assignments
1127 Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
1130 -- Now construct the loop from the inside out, with the last subscript
1131 -- varying most rapidly. Note that Assign is first the raw assignment
1132 -- statement, and then subsequently the loop that wraps it up.
1134 for J in reverse 1 .. Ndim loop
1136 Make_Block_Statement (Loc,
1137 Declarations => New_List (
1138 Make_Object_Declaration (Loc,
1139 Defining_Identifier => Rnn (J),
1140 Object_Definition =>
1141 New_Occurrence_Of (R_Index_Type (J), Loc),
1143 Make_Attribute_Reference (Loc,
1144 Prefix => New_Occurrence_Of (R_Index_Type (J), Loc),
1145 Attribute_Name => F_Or_L))),
1147 Handled_Statement_Sequence =>
1148 Make_Handled_Sequence_Of_Statements (Loc,
1149 Statements => New_List (
1150 Make_Implicit_Loop_Statement (N,
1152 Make_Iteration_Scheme (Loc,
1153 Loop_Parameter_Specification =>
1154 Make_Loop_Parameter_Specification (Loc,
1155 Defining_Identifier => Lnn (J),
1156 Reverse_Present => Rev,
1157 Discrete_Subtype_Definition =>
1158 New_Reference_To (L_Index_Type (J), Loc))),
1160 Statements => New_List (Assign, Build_Step (J))))));
1164 end Expand_Assign_Array_Loop;
1166 --------------------------
1167 -- Expand_Assign_Record --
1168 --------------------------
1170 procedure Expand_Assign_Record (N : Node_Id) is
1171 Lhs : constant Node_Id := Name (N);
1172 Rhs : Node_Id := Expression (N);
1173 L_Typ : constant Entity_Id := Base_Type (Etype (Lhs));
1176 -- If change of representation, then extract the real right hand side
1177 -- from the type conversion, and proceed with component-wise assignment,
1178 -- since the two types are not the same as far as the back end is
1181 if Change_Of_Representation (N) then
1182 Rhs := Expression (Rhs);
1184 -- If this may be a case of a large bit aligned component, then proceed
1185 -- with component-wise assignment, to avoid possible clobbering of other
1186 -- components sharing bits in the first or last byte of the component to
1189 elsif Possible_Bit_Aligned_Component (Lhs)
1191 Possible_Bit_Aligned_Component (Rhs)
1195 -- If we have a tagged type that has a complete record representation
1196 -- clause, we must do we must do component-wise assignments, since child
1197 -- types may have used gaps for their components, and we might be
1198 -- dealing with a view conversion.
1200 elsif Is_Fully_Repped_Tagged_Type (L_Typ) then
1203 -- If neither condition met, then nothing special to do, the back end
1204 -- can handle assignment of the entire component as a single entity.
1210 -- At this stage we know that we must do a component wise assignment
1213 Loc : constant Source_Ptr := Sloc (N);
1214 R_Typ : constant Entity_Id := Base_Type (Etype (Rhs));
1215 Decl : constant Node_Id := Declaration_Node (R_Typ);
1219 function Find_Component
1221 Comp : Entity_Id) return Entity_Id;
1222 -- Find the component with the given name in the underlying record
1223 -- declaration for Typ. We need to use the actual entity because the
1224 -- type may be private and resolution by identifier alone would fail.
1226 function Make_Field_Expr
1227 (Comp_Ent : Entity_Id;
1228 U_U : Boolean) return Node_Id;
1229 -- Common processing for one component for Make_Component_List_Assign
1230 -- and Make_Field_Assign. Return the expression to be assigned for
1231 -- component Comp_Ent.
1233 function Make_Component_List_Assign
1235 U_U : Boolean := False) return List_Id;
1236 -- Returns a sequence of statements to assign the components that
1237 -- are referenced in the given component list. The flag U_U is
1238 -- used to force the usage of the inferred value of the variant
1239 -- part expression as the switch for the generated case statement.
1241 function Make_Field_Assign
1243 U_U : Boolean := False) return Node_Id;
1244 -- Given C, the entity for a discriminant or component, build an
1245 -- assignment for the corresponding field values. The flag U_U
1246 -- signals the presence of an Unchecked_Union and forces the usage
1247 -- of the inferred discriminant value of C as the right hand side
1248 -- of the assignment.
1250 function Make_Field_Assigns (CI : List_Id) return List_Id;
1251 -- Given CI, a component items list, construct series of statements
1252 -- for fieldwise assignment of the corresponding components.
1254 --------------------
1255 -- Find_Component --
1256 --------------------
1258 function Find_Component
1260 Comp : Entity_Id) return Entity_Id
1262 Utyp : constant Entity_Id := Underlying_Type (Typ);
1266 C := First_Entity (Utyp);
1267 while Present (C) loop
1268 if Chars (C) = Chars (Comp) then
1275 raise Program_Error;
1278 --------------------------------
1279 -- Make_Component_List_Assign --
1280 --------------------------------
1282 function Make_Component_List_Assign
1284 U_U : Boolean := False) return List_Id
1286 CI : constant List_Id := Component_Items (CL);
1287 VP : constant Node_Id := Variant_Part (CL);
1296 Result := Make_Field_Assigns (CI);
1298 if Present (VP) then
1299 V := First_Non_Pragma (Variants (VP));
1301 while Present (V) loop
1303 DC := First (Discrete_Choices (V));
1304 while Present (DC) loop
1305 Append_To (DCH, New_Copy_Tree (DC));
1310 Make_Case_Statement_Alternative (Loc,
1311 Discrete_Choices => DCH,
1313 Make_Component_List_Assign (Component_List (V))));
1314 Next_Non_Pragma (V);
1318 Make_Case_Statement (Loc,
1319 Expression => Make_Field_Expr (Entity (Name (VP)), U_U),
1320 Alternatives => Alts));
1324 end Make_Component_List_Assign;
1326 -----------------------
1327 -- Make_Field_Assign --
1328 -----------------------
1330 function Make_Field_Assign
1332 U_U : Boolean := False) return Node_Id
1337 -- In the case of an Unchecked_Union, use the discriminant
1338 -- constraint value as on the right hand side of the assignment.
1341 Make_Assignment_Statement (Loc,
1343 Make_Selected_Component (Loc,
1344 Prefix => Duplicate_Subexpr (Lhs),
1346 New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
1347 Expression => Make_Field_Expr (C, U_U));
1349 -- Set Assignment_OK, so discriminants can be assigned
1351 Set_Assignment_OK (Name (A), True);
1353 if Componentwise_Assignment (N)
1354 and then Nkind (Name (A)) = N_Selected_Component
1355 and then Chars (Selector_Name (Name (A))) = Name_uParent
1357 Set_Componentwise_Assignment (A);
1361 end Make_Field_Assign;
1363 ------------------------
1364 -- Make_Field_Assigns --
1365 ------------------------
1367 function Make_Field_Assigns (CI : List_Id) return List_Id is
1374 while Present (Item) loop
1376 -- Look for components, but exclude _tag field assignment if
1377 -- the special Componentwise_Assignment flag is set.
1379 if Nkind (Item) = N_Component_Declaration
1380 and then not (Is_Tag (Defining_Identifier (Item))
1381 and then Componentwise_Assignment (N))
1384 (Result, Make_Field_Assign (Defining_Identifier (Item)));
1391 end Make_Field_Assigns;
1393 ---------------------
1394 -- Make_Field_Expr --
1395 ---------------------
1397 function Make_Field_Expr
1398 (Comp_Ent : Entity_Id;
1399 U_U : Boolean) return Node_Id
1402 -- If we have an Unchecked_Union, use the value of the inferred
1403 -- discriminant of the variant part expression.
1407 New_Copy (Get_Discriminant_Value
1410 Discriminant_Constraint (Etype (Rhs))));
1413 Make_Selected_Component (Loc,
1414 Prefix => Duplicate_Subexpr (Rhs),
1415 Selector_Name => New_Occurrence_Of (Comp_Ent, Loc));
1417 end Make_Field_Expr;
1419 -- Start of processing for Expand_Assign_Record
1422 -- Note that we use the base types for this processing. This results
1423 -- in some extra work in the constrained case, but the change of
1424 -- representation case is so unusual that it is not worth the effort.
1426 -- First copy the discriminants. This is done unconditionally. It
1427 -- is required in the unconstrained left side case, and also in the
1428 -- case where this assignment was constructed during the expansion
1429 -- of a type conversion (since initialization of discriminants is
1430 -- suppressed in this case). It is unnecessary but harmless in
1433 if Has_Discriminants (L_Typ) then
1434 F := First_Discriminant (R_Typ);
1435 while Present (F) loop
1437 -- If we are expanding the initialization of a derived record
1438 -- that constrains or renames discriminants of the parent, we
1439 -- must use the corresponding discriminant in the parent.
1446 and then Present (Corresponding_Discriminant (F))
1448 CF := Corresponding_Discriminant (F);
1453 if Is_Unchecked_Union (Base_Type (R_Typ)) then
1454 Insert_Action (N, Make_Field_Assign (CF, True));
1456 Insert_Action (N, Make_Field_Assign (CF));
1459 Next_Discriminant (F);
1464 -- We know the underlying type is a record, but its current view
1465 -- may be private. We must retrieve the usable record declaration.
1467 if Nkind_In (Decl, N_Private_Type_Declaration,
1468 N_Private_Extension_Declaration)
1469 and then Present (Full_View (R_Typ))
1471 RDef := Type_Definition (Declaration_Node (Full_View (R_Typ)));
1473 RDef := Type_Definition (Decl);
1476 if Nkind (RDef) = N_Derived_Type_Definition then
1477 RDef := Record_Extension_Part (RDef);
1480 if Nkind (RDef) = N_Record_Definition
1481 and then Present (Component_List (RDef))
1483 if Is_Unchecked_Union (R_Typ) then
1485 Make_Component_List_Assign (Component_List (RDef), True));
1488 (N, Make_Component_List_Assign (Component_List (RDef)));
1491 Rewrite (N, Make_Null_Statement (Loc));
1494 end Expand_Assign_Record;
1496 -----------------------------------
1497 -- Expand_N_Assignment_Statement --
1498 -----------------------------------
1500 -- This procedure implements various cases where an assignment statement
1501 -- cannot just be passed on to the back end in untransformed state.
1503 procedure Expand_N_Assignment_Statement (N : Node_Id) is
1504 Loc : constant Source_Ptr := Sloc (N);
1505 Lhs : constant Node_Id := Name (N);
1506 Rhs : constant Node_Id := Expression (N);
1507 Typ : constant Entity_Id := Underlying_Type (Etype (Lhs));
1511 -- Special case to check right away, if the Componentwise_Assignment
1512 -- flag is set, this is a reanalysis from the expansion of the primitive
1513 -- assignment procedure for a tagged type, and all we need to do is to
1514 -- expand to assignment of components, because otherwise, we would get
1515 -- infinite recursion (since this looks like a tagged assignment which
1516 -- would normally try to *call* the primitive assignment procedure).
1518 if Componentwise_Assignment (N) then
1519 Expand_Assign_Record (N);
1523 -- Defend against invalid subscripts on left side if we are in standard
1524 -- validity checking mode. No need to do this if we are checking all
1527 -- Note that we do this right away, because there are some early return
1528 -- paths in this procedure, and this is required on all paths.
1530 if Validity_Checks_On
1531 and then Validity_Check_Default
1532 and then not Validity_Check_Subscripts
1534 Check_Valid_Lvalue_Subscripts (Lhs);
1537 -- Ada 2005 (AI-327): Handle assignment to priority of protected object
1539 -- Rewrite an assignment to X'Priority into a run-time call
1541 -- For example: X'Priority := New_Prio_Expr;
1542 -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr);
1544 -- Note that although X'Priority is notionally an object, it is quite
1545 -- deliberately not defined as an aliased object in the RM. This means
1546 -- that it works fine to rewrite it as a call, without having to worry
1547 -- about complications that would other arise from X'Priority'Access,
1548 -- which is illegal, because of the lack of aliasing.
1550 if Ada_Version >= Ada_05 then
1553 Conctyp : Entity_Id;
1556 RT_Subprg_Name : Node_Id;
1559 -- Handle chains of renamings
1562 while Nkind (Ent) in N_Has_Entity
1563 and then Present (Entity (Ent))
1564 and then Present (Renamed_Object (Entity (Ent)))
1566 Ent := Renamed_Object (Entity (Ent));
1569 -- The attribute Priority applied to protected objects has been
1570 -- previously expanded into a call to the Get_Ceiling run-time
1573 if Nkind (Ent) = N_Function_Call
1574 and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling)
1576 Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling))
1578 -- Look for the enclosing concurrent type
1580 Conctyp := Current_Scope;
1581 while not Is_Concurrent_Type (Conctyp) loop
1582 Conctyp := Scope (Conctyp);
1585 pragma Assert (Is_Protected_Type (Conctyp));
1587 -- Generate the first actual of the call
1589 Subprg := Current_Scope;
1590 while not Present (Protected_Body_Subprogram (Subprg)) loop
1591 Subprg := Scope (Subprg);
1594 -- Select the appropriate run-time call
1596 if Number_Entries (Conctyp) = 0 then
1598 New_Reference_To (RTE (RE_Set_Ceiling), Loc);
1601 New_Reference_To (RTE (RO_PE_Set_Ceiling), Loc);
1605 Make_Procedure_Call_Statement (Loc,
1606 Name => RT_Subprg_Name,
1607 Parameter_Associations => New_List (
1608 New_Copy_Tree (First (Parameter_Associations (Ent))),
1609 Relocate_Node (Expression (N))));
1618 -- First deal with generation of range check if required
1620 if Do_Range_Check (Rhs) then
1621 Set_Do_Range_Check (Rhs, False);
1622 Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed);
1625 -- Check for a special case where a high level transformation is
1626 -- required. If we have either of:
1631 -- where P is a reference to a bit packed array, then we have to unwind
1632 -- the assignment. The exact meaning of being a reference to a bit
1633 -- packed array is as follows:
1635 -- An indexed component whose prefix is a bit packed array is a
1636 -- reference to a bit packed array.
1638 -- An indexed component or selected component whose prefix is a
1639 -- reference to a bit packed array is itself a reference ot a
1640 -- bit packed array.
1642 -- The required transformation is
1644 -- Tnn : prefix_type := P;
1645 -- Tnn.field := rhs;
1650 -- Tnn : prefix_type := P;
1651 -- Tnn (subscr) := rhs;
1654 -- Since P is going to be evaluated more than once, any subscripts
1655 -- in P must have their evaluation forced.
1657 if Nkind_In (Lhs, N_Indexed_Component, N_Selected_Component)
1658 and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs))
1661 BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs));
1662 BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr);
1663 Tnn : constant Entity_Id :=
1664 Make_Temporary (Loc, 'T', BPAR_Expr);
1667 -- Insert the post assignment first, because we want to copy the
1668 -- BPAR_Expr tree before it gets analyzed in the context of the
1669 -- pre assignment. Note that we do not analyze the post assignment
1670 -- yet (we cannot till we have completed the analysis of the pre
1671 -- assignment). As usual, the analysis of this post assignment
1672 -- will happen on its own when we "run into" it after finishing
1673 -- the current assignment.
1676 Make_Assignment_Statement (Loc,
1677 Name => New_Copy_Tree (BPAR_Expr),
1678 Expression => New_Occurrence_Of (Tnn, Loc)));
1680 -- At this stage BPAR_Expr is a reference to a bit packed array
1681 -- where the reference was not expanded in the original tree,
1682 -- since it was on the left side of an assignment. But in the
1683 -- pre-assignment statement (the object definition), BPAR_Expr
1684 -- will end up on the right hand side, and must be reexpanded. To
1685 -- achieve this, we reset the analyzed flag of all selected and
1686 -- indexed components down to the actual indexed component for
1687 -- the packed array.
1691 Set_Analyzed (Exp, False);
1694 (Exp, N_Selected_Component, N_Indexed_Component)
1696 Exp := Prefix (Exp);
1702 -- Now we can insert and analyze the pre-assignment
1704 -- If the right-hand side requires a transient scope, it has
1705 -- already been placed on the stack. However, the declaration is
1706 -- inserted in the tree outside of this scope, and must reflect
1707 -- the proper scope for its variable. This awkward bit is forced
1708 -- by the stricter scope discipline imposed by GCC 2.97.
1711 Uses_Transient_Scope : constant Boolean :=
1713 and then N = Node_To_Be_Wrapped;
1716 if Uses_Transient_Scope then
1717 Push_Scope (Scope (Current_Scope));
1720 Insert_Before_And_Analyze (N,
1721 Make_Object_Declaration (Loc,
1722 Defining_Identifier => Tnn,
1723 Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc),
1724 Expression => BPAR_Expr));
1726 if Uses_Transient_Scope then
1731 -- Now fix up the original assignment and continue processing
1733 Rewrite (Prefix (Lhs),
1734 New_Occurrence_Of (Tnn, Loc));
1736 -- We do not need to reanalyze that assignment, and we do not need
1737 -- to worry about references to the temporary, but we do need to
1738 -- make sure that the temporary is not marked as a true constant
1739 -- since we now have a generated assignment to it!
1741 Set_Is_True_Constant (Tnn, False);
1745 -- When we have the appropriate type of aggregate in the expression (it
1746 -- has been determined during analysis of the aggregate by setting the
1747 -- delay flag), let's perform in place assignment and thus avoid
1748 -- creating a temporary.
1750 if Is_Delayed_Aggregate (Rhs) then
1751 Convert_Aggr_In_Assignment (N);
1752 Rewrite (N, Make_Null_Statement (Loc));
1757 -- Apply discriminant check if required. If Lhs is an access type to a
1758 -- designated type with discriminants, we must always check.
1760 if Has_Discriminants (Etype (Lhs)) then
1762 -- Skip discriminant check if change of representation. Will be
1763 -- done when the change of representation is expanded out.
1765 if not Change_Of_Representation (N) then
1766 Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs);
1769 -- If the type is private without discriminants, and the full type
1770 -- has discriminants (necessarily with defaults) a check may still be
1771 -- necessary if the Lhs is aliased. The private determinants must be
1772 -- visible to build the discriminant constraints.
1774 -- Only an explicit dereference that comes from source indicates
1775 -- aliasing. Access to formals of protected operations and entries
1776 -- create dereferences but are not semantic aliasings.
1778 elsif Is_Private_Type (Etype (Lhs))
1779 and then Has_Discriminants (Typ)
1780 and then Nkind (Lhs) = N_Explicit_Dereference
1781 and then Comes_From_Source (Lhs)
1784 Lt : constant Entity_Id := Etype (Lhs);
1786 Set_Etype (Lhs, Typ);
1787 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1788 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1789 Set_Etype (Lhs, Lt);
1792 -- If the Lhs has a private type with unknown discriminants, it
1793 -- may have a full view with discriminants, but those are nameable
1794 -- only in the underlying type, so convert the Rhs to it before
1795 -- potential checking.
1797 elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs)))
1798 and then Has_Discriminants (Typ)
1800 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1801 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1803 -- In the access type case, we need the same discriminant check, and
1804 -- also range checks if we have an access to constrained array.
1806 elsif Is_Access_Type (Etype (Lhs))
1807 and then Is_Constrained (Designated_Type (Etype (Lhs)))
1809 if Has_Discriminants (Designated_Type (Etype (Lhs))) then
1811 -- Skip discriminant check if change of representation. Will be
1812 -- done when the change of representation is expanded out.
1814 if not Change_Of_Representation (N) then
1815 Apply_Discriminant_Check (Rhs, Etype (Lhs));
1818 elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then
1819 Apply_Range_Check (Rhs, Etype (Lhs));
1821 if Is_Constrained (Etype (Lhs)) then
1822 Apply_Length_Check (Rhs, Etype (Lhs));
1825 if Nkind (Rhs) = N_Allocator then
1827 Target_Typ : constant Entity_Id := Etype (Expression (Rhs));
1828 C_Es : Check_Result;
1835 Etype (Designated_Type (Etype (Lhs))));
1847 -- Apply range check for access type case
1849 elsif Is_Access_Type (Etype (Lhs))
1850 and then Nkind (Rhs) = N_Allocator
1851 and then Nkind (Expression (Rhs)) = N_Qualified_Expression
1853 Analyze_And_Resolve (Expression (Rhs));
1855 (Expression (Rhs), Designated_Type (Etype (Lhs)));
1858 -- Ada 2005 (AI-231): Generate the run-time check
1860 if Is_Access_Type (Typ)
1861 and then Can_Never_Be_Null (Etype (Lhs))
1862 and then not Can_Never_Be_Null (Etype (Rhs))
1864 Apply_Constraint_Check (Rhs, Etype (Lhs));
1867 -- Case of assignment to a bit packed array element
1869 if Nkind (Lhs) = N_Indexed_Component
1870 and then Is_Bit_Packed_Array (Etype (Prefix (Lhs)))
1872 Expand_Bit_Packed_Element_Set (N);
1875 -- Build-in-place function call case. Note that we're not yet doing
1876 -- build-in-place for user-written assignment statements (the assignment
1877 -- here came from an aggregate.)
1879 elsif Ada_Version >= Ada_05
1880 and then Is_Build_In_Place_Function_Call (Rhs)
1882 Make_Build_In_Place_Call_In_Assignment (N, Rhs);
1884 elsif Is_Tagged_Type (Typ) and then Is_Value_Type (Etype (Lhs)) then
1886 -- Nothing to do for valuetypes
1887 -- ??? Set_Scope_Is_Transient (False);
1891 elsif Is_Tagged_Type (Typ)
1892 or else (Needs_Finalization (Typ) and then not Is_Array_Type (Typ))
1894 Tagged_Case : declare
1895 L : List_Id := No_List;
1896 Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N);
1899 -- In the controlled case, we ensure that function calls are
1900 -- evaluated before finalizing the target. In all cases, it makes
1901 -- the expansion easier if the side-effects are removed first.
1903 Remove_Side_Effects (Lhs);
1904 Remove_Side_Effects (Rhs);
1906 -- Avoid recursion in the mechanism
1910 -- If dispatching assignment, we need to dispatch to _assign
1912 if Is_Class_Wide_Type (Typ)
1914 -- If the type is tagged, we may as well use the predefined
1915 -- primitive assignment. This avoids inlining a lot of code
1916 -- and in the class-wide case, the assignment is replaced by
1917 -- dispatch call to _assign. Note that this cannot be done when
1918 -- discriminant checks are locally suppressed (as in extension
1919 -- aggregate expansions) because otherwise the discriminant
1920 -- check will be performed within the _assign call. It is also
1921 -- suppressed for assignments created by the expander that
1922 -- correspond to initializations, where we do want to copy the
1923 -- tag (No_Ctrl_Actions flag set True) by the expander and we
1924 -- do not need to mess with tags ever (Expand_Ctrl_Actions flag
1925 -- is set True in this case).
1927 or else (Is_Tagged_Type (Typ)
1928 and then not Is_Value_Type (Etype (Lhs))
1929 and then Chars (Current_Scope) /= Name_uAssign
1930 and then Expand_Ctrl_Actions
1931 and then not Discriminant_Checks_Suppressed (Empty))
1933 -- Fetch the primitive op _assign and proper type to call it.
1934 -- Because of possible conflicts between private and full view,
1935 -- fetch the proper type directly from the operation profile.
1938 Op : constant Entity_Id :=
1939 Find_Prim_Op (Typ, Name_uAssign);
1940 F_Typ : Entity_Id := Etype (First_Formal (Op));
1943 -- If the assignment is dispatching, make sure to use the
1946 if Is_Class_Wide_Type (Typ) then
1947 F_Typ := Class_Wide_Type (F_Typ);
1952 -- In case of assignment to a class-wide tagged type, before
1953 -- the assignment we generate run-time check to ensure that
1954 -- the tags of source and target match.
1956 if Is_Class_Wide_Type (Typ)
1957 and then Is_Tagged_Type (Typ)
1958 and then Is_Tagged_Type (Underlying_Type (Etype (Rhs)))
1960 -- Do not generate a tag check when the target object is
1961 -- an interface since the expression of the right hand
1962 -- side must only cover the interface.
1964 and then not Is_Interface (Typ)
1967 Make_Raise_Constraint_Error (Loc,
1971 Make_Selected_Component (Loc,
1972 Prefix => Duplicate_Subexpr (Lhs),
1974 Make_Identifier (Loc,
1975 Chars => Name_uTag)),
1977 Make_Selected_Component (Loc,
1978 Prefix => Duplicate_Subexpr (Rhs),
1980 Make_Identifier (Loc,
1981 Chars => Name_uTag))),
1982 Reason => CE_Tag_Check_Failed));
1986 Make_Procedure_Call_Statement (Loc,
1987 Name => New_Reference_To (Op, Loc),
1988 Parameter_Associations => New_List (
1989 Unchecked_Convert_To (F_Typ,
1990 Duplicate_Subexpr (Lhs)),
1991 Unchecked_Convert_To (F_Typ,
1992 Duplicate_Subexpr (Rhs)))));
1996 L := Make_Tag_Ctrl_Assignment (N);
1998 -- We can't afford to have destructive Finalization Actions in
1999 -- the Self assignment case, so if the target and the source
2000 -- are not obviously different, code is generated to avoid the
2001 -- self assignment case:
2003 -- if lhs'address /= rhs'address then
2004 -- <code for controlled and/or tagged assignment>
2007 -- Skip this if Restriction (No_Finalization) is active
2009 if not Statically_Different (Lhs, Rhs)
2010 and then Expand_Ctrl_Actions
2011 and then not Restriction_Active (No_Finalization)
2014 Make_Implicit_If_Statement (N,
2018 Make_Attribute_Reference (Loc,
2019 Prefix => Duplicate_Subexpr (Lhs),
2020 Attribute_Name => Name_Address),
2023 Make_Attribute_Reference (Loc,
2024 Prefix => Duplicate_Subexpr (Rhs),
2025 Attribute_Name => Name_Address)),
2027 Then_Statements => L));
2030 -- We need to set up an exception handler for implementing
2031 -- 7.6.1(18). The remaining adjustments are tackled by the
2032 -- implementation of adjust for record_controllers (see
2035 -- This is skipped if we have no finalization
2037 if Expand_Ctrl_Actions
2038 and then not Restriction_Active (No_Finalization)
2041 Make_Block_Statement (Loc,
2042 Handled_Statement_Sequence =>
2043 Make_Handled_Sequence_Of_Statements (Loc,
2045 Exception_Handlers => New_List (
2046 Make_Handler_For_Ctrl_Operation (Loc)))));
2051 Make_Block_Statement (Loc,
2052 Handled_Statement_Sequence =>
2053 Make_Handled_Sequence_Of_Statements (Loc, Statements => L)));
2055 -- If no restrictions on aborts, protect the whole assignment
2056 -- for controlled objects as per 9.8(11).
2058 if Needs_Finalization (Typ)
2059 and then Expand_Ctrl_Actions
2060 and then Abort_Allowed
2063 Blk : constant Entity_Id :=
2065 (E_Block, Current_Scope, Sloc (N), 'B');
2068 Set_Scope (Blk, Current_Scope);
2069 Set_Etype (Blk, Standard_Void_Type);
2070 Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N)));
2072 Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer));
2073 Set_At_End_Proc (Handled_Statement_Sequence (N),
2074 New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc));
2075 Expand_At_End_Handler
2076 (Handled_Statement_Sequence (N), Blk);
2080 -- N has been rewritten to a block statement for which it is
2081 -- known by construction that no checks are necessary: analyze
2082 -- it with all checks suppressed.
2084 Analyze (N, Suppress => All_Checks);
2090 elsif Is_Array_Type (Typ) then
2092 Actual_Rhs : Node_Id := Rhs;
2095 while Nkind_In (Actual_Rhs, N_Type_Conversion,
2096 N_Qualified_Expression)
2098 Actual_Rhs := Expression (Actual_Rhs);
2101 Expand_Assign_Array (N, Actual_Rhs);
2107 elsif Is_Record_Type (Typ) then
2108 Expand_Assign_Record (N);
2111 -- Scalar types. This is where we perform the processing related to the
2112 -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid
2115 elsif Is_Scalar_Type (Typ) then
2117 -- Case where right side is known valid
2119 if Expr_Known_Valid (Rhs) then
2121 -- Here the right side is valid, so it is fine. The case to deal
2122 -- with is when the left side is a local variable reference whose
2123 -- value is not currently known to be valid. If this is the case,
2124 -- and the assignment appears in an unconditional context, then
2125 -- we can mark the left side as now being valid if one of these
2126 -- conditions holds:
2128 -- The expression of the right side has Do_Range_Check set so
2129 -- that we know a range check will be performed. Note that it
2130 -- can be the case that a range check is omitted because we
2131 -- make the assumption that we can assume validity for operands
2132 -- appearing in the right side in determining whether a range
2133 -- check is required
2135 -- The subtype of the right side matches the subtype of the
2136 -- left side. In this case, even though we have not checked
2137 -- the range of the right side, we know it is in range of its
2138 -- subtype if the expression is valid.
2140 if Is_Local_Variable_Reference (Lhs)
2141 and then not Is_Known_Valid (Entity (Lhs))
2142 and then In_Unconditional_Context (N)
2144 if Do_Range_Check (Rhs)
2145 or else Etype (Lhs) = Etype (Rhs)
2147 Set_Is_Known_Valid (Entity (Lhs), True);
2151 -- Case where right side may be invalid in the sense of the RM
2152 -- reference above. The RM does not require that we check for the
2153 -- validity on an assignment, but it does require that the assignment
2154 -- of an invalid value not cause erroneous behavior.
2156 -- The general approach in GNAT is to use the Is_Known_Valid flag
2157 -- to avoid the need for validity checking on assignments. However
2158 -- in some cases, we have to do validity checking in order to make
2159 -- sure that the setting of this flag is correct.
2162 -- Validate right side if we are validating copies
2164 if Validity_Checks_On
2165 and then Validity_Check_Copies
2167 -- Skip this if left hand side is an array or record component
2168 -- and elementary component validity checks are suppressed.
2170 if Nkind_In (Lhs, N_Selected_Component, N_Indexed_Component)
2171 and then not Validity_Check_Components
2178 -- We can propagate this to the left side where appropriate
2180 if Is_Local_Variable_Reference (Lhs)
2181 and then not Is_Known_Valid (Entity (Lhs))
2182 and then In_Unconditional_Context (N)
2184 Set_Is_Known_Valid (Entity (Lhs), True);
2187 -- Otherwise check to see what should be done
2189 -- If left side is a local variable, then we just set its flag to
2190 -- indicate that its value may no longer be valid, since we are
2191 -- copying a potentially invalid value.
2193 elsif Is_Local_Variable_Reference (Lhs) then
2194 Set_Is_Known_Valid (Entity (Lhs), False);
2196 -- Check for case of a nonlocal variable on the left side which
2197 -- is currently known to be valid. In this case, we simply ensure
2198 -- that the right side is valid. We only play the game of copying
2199 -- validity status for local variables, since we are doing this
2200 -- statically, not by tracing the full flow graph.
2202 elsif Is_Entity_Name (Lhs)
2203 and then Is_Known_Valid (Entity (Lhs))
2205 -- Note: If Validity_Checking mode is set to none, we ignore
2206 -- the Ensure_Valid call so don't worry about that case here.
2210 -- In all other cases, we can safely copy an invalid value without
2211 -- worrying about the status of the left side. Since it is not a
2212 -- variable reference it will not be considered
2213 -- as being known to be valid in any case.
2222 when RE_Not_Available =>
2224 end Expand_N_Assignment_Statement;
2226 ------------------------------
2227 -- Expand_N_Block_Statement --
2228 ------------------------------
2230 -- Encode entity names defined in block statement
2232 procedure Expand_N_Block_Statement (N : Node_Id) is
2234 Qualify_Entity_Names (N);
2235 end Expand_N_Block_Statement;
2237 -----------------------------
2238 -- Expand_N_Case_Statement --
2239 -----------------------------
2241 procedure Expand_N_Case_Statement (N : Node_Id) is
2242 Loc : constant Source_Ptr := Sloc (N);
2243 Expr : constant Node_Id := Expression (N);
2251 -- Check for the situation where we know at compile time which branch
2254 if Compile_Time_Known_Value (Expr) then
2255 Alt := Find_Static_Alternative (N);
2257 -- Move statements from this alternative after the case statement.
2258 -- They are already analyzed, so will be skipped by the analyzer.
2260 Insert_List_After (N, Statements (Alt));
2262 -- That leaves the case statement as a shell. So now we can kill all
2263 -- other alternatives in the case statement.
2265 Kill_Dead_Code (Expression (N));
2271 -- Loop through case alternatives, skipping pragmas, and skipping
2272 -- the one alternative that we select (and therefore retain).
2274 A := First (Alternatives (N));
2275 while Present (A) loop
2277 and then Nkind (A) = N_Case_Statement_Alternative
2279 Kill_Dead_Code (Statements (A), Warn_On_Deleted_Code);
2286 Rewrite (N, Make_Null_Statement (Loc));
2290 -- Here if the choice is not determined at compile time
2293 Last_Alt : constant Node_Id := Last (Alternatives (N));
2295 Others_Present : Boolean;
2296 Others_Node : Node_Id;
2298 Then_Stms : List_Id;
2299 Else_Stms : List_Id;
2302 if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then
2303 Others_Present := True;
2304 Others_Node := Last_Alt;
2306 Others_Present := False;
2309 -- First step is to worry about possible invalid argument. The RM
2310 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
2311 -- outside the base range), then Constraint_Error must be raised.
2313 -- Case of validity check required (validity checks are on, the
2314 -- expression is not known to be valid, and the case statement
2315 -- comes from source -- no need to validity check internally
2316 -- generated case statements).
2318 if Validity_Check_Default then
2319 Ensure_Valid (Expr);
2322 -- If there is only a single alternative, just replace it with the
2323 -- sequence of statements since obviously that is what is going to
2324 -- be executed in all cases.
2326 Len := List_Length (Alternatives (N));
2329 -- We still need to evaluate the expression if it has any
2332 Remove_Side_Effects (Expression (N));
2334 Insert_List_After (N, Statements (First (Alternatives (N))));
2336 -- That leaves the case statement as a shell. The alternative that
2337 -- will be executed is reset to a null list. So now we can kill
2338 -- the entire case statement.
2340 Kill_Dead_Code (Expression (N));
2341 Rewrite (N, Make_Null_Statement (Loc));
2345 -- An optimization. If there are only two alternatives, and only
2346 -- a single choice, then rewrite the whole case statement as an
2347 -- if statement, since this can result in subsequent optimizations.
2348 -- This helps not only with case statements in the source of a
2349 -- simple form, but also with generated code (discriminant check
2350 -- functions in particular)
2353 Chlist := Discrete_Choices (First (Alternatives (N)));
2355 if List_Length (Chlist) = 1 then
2356 Choice := First (Chlist);
2358 Then_Stms := Statements (First (Alternatives (N)));
2359 Else_Stms := Statements (Last (Alternatives (N)));
2361 -- For TRUE, generate "expression", not expression = true
2363 if Nkind (Choice) = N_Identifier
2364 and then Entity (Choice) = Standard_True
2366 Cond := Expression (N);
2368 -- For FALSE, generate "expression" and switch then/else
2370 elsif Nkind (Choice) = N_Identifier
2371 and then Entity (Choice) = Standard_False
2373 Cond := Expression (N);
2374 Else_Stms := Statements (First (Alternatives (N)));
2375 Then_Stms := Statements (Last (Alternatives (N)));
2377 -- For a range, generate "expression in range"
2379 elsif Nkind (Choice) = N_Range
2380 or else (Nkind (Choice) = N_Attribute_Reference
2381 and then Attribute_Name (Choice) = Name_Range)
2382 or else (Is_Entity_Name (Choice)
2383 and then Is_Type (Entity (Choice)))
2384 or else Nkind (Choice) = N_Subtype_Indication
2388 Left_Opnd => Expression (N),
2389 Right_Opnd => Relocate_Node (Choice));
2391 -- For any other subexpression "expression = value"
2396 Left_Opnd => Expression (N),
2397 Right_Opnd => Relocate_Node (Choice));
2400 -- Now rewrite the case as an IF
2403 Make_If_Statement (Loc,
2405 Then_Statements => Then_Stms,
2406 Else_Statements => Else_Stms));
2412 -- If the last alternative is not an Others choice, replace it with
2413 -- an N_Others_Choice. Note that we do not bother to call Analyze on
2414 -- the modified case statement, since it's only effect would be to
2415 -- compute the contents of the Others_Discrete_Choices which is not
2416 -- needed by the back end anyway.
2418 -- The reason we do this is that the back end always needs some
2419 -- default for a switch, so if we have not supplied one in the
2420 -- processing above for validity checking, then we need to supply
2423 if not Others_Present then
2424 Others_Node := Make_Others_Choice (Sloc (Last_Alt));
2425 Set_Others_Discrete_Choices
2426 (Others_Node, Discrete_Choices (Last_Alt));
2427 Set_Discrete_Choices (Last_Alt, New_List (Others_Node));
2430 end Expand_N_Case_Statement;
2432 -----------------------------
2433 -- Expand_N_Exit_Statement --
2434 -----------------------------
2436 -- The only processing required is to deal with a possible C/Fortran
2437 -- boolean value used as the condition for the exit statement.
2439 procedure Expand_N_Exit_Statement (N : Node_Id) is
2441 Adjust_Condition (Condition (N));
2442 end Expand_N_Exit_Statement;
2444 ----------------------------------------
2445 -- Expand_N_Extended_Return_Statement --
2446 ----------------------------------------
2448 -- If there is a Handled_Statement_Sequence, we rewrite this:
2450 -- return Result : T := <expression> do
2451 -- <handled_seq_of_stms>
2457 -- Result : T := <expression>;
2459 -- <handled_seq_of_stms>
2463 -- Otherwise (no Handled_Statement_Sequence), we rewrite this:
2465 -- return Result : T := <expression>;
2469 -- return <expression>;
2471 -- unless it's build-in-place or there's no <expression>, in which case
2475 -- Result : T := <expression>;
2480 -- Note that this case could have been written by the user as an extended
2481 -- return statement, or could have been transformed to this from a simple
2482 -- return statement.
2484 -- That is, we need to have a reified return object if there are statements
2485 -- (which might refer to it) or if we're doing build-in-place (so we can
2486 -- set its address to the final resting place or if there is no expression
2487 -- (in which case default initial values might need to be set).
2489 procedure Expand_N_Extended_Return_Statement (N : Node_Id) is
2490 Loc : constant Source_Ptr := Sloc (N);
2492 Return_Object_Entity : constant Entity_Id :=
2493 First_Entity (Return_Statement_Entity (N));
2494 Return_Object_Decl : constant Node_Id :=
2495 Parent (Return_Object_Entity);
2496 Parent_Function : constant Entity_Id :=
2497 Return_Applies_To (Return_Statement_Entity (N));
2498 Parent_Function_Typ : constant Entity_Id := Etype (Parent_Function);
2499 Is_Build_In_Place : constant Boolean :=
2500 Is_Build_In_Place_Function (Parent_Function);
2502 Return_Stm : Node_Id;
2503 Statements : List_Id;
2504 Handled_Stm_Seq : Node_Id;
2508 function Has_Controlled_Parts (Typ : Entity_Id) return Boolean;
2509 -- Determine whether type Typ is controlled or contains a controlled
2512 function Move_Activation_Chain return Node_Id;
2513 -- Construct a call to System.Tasking.Stages.Move_Activation_Chain
2515 -- From current activation chain
2516 -- To activation chain passed in by the caller
2517 -- New_Master master passed in by the caller
2519 function Move_Final_List return Node_Id;
2520 -- Construct call to System.Finalization_Implementation.Move_Final_List
2523 -- From finalization list of the return statement
2524 -- To finalization list passed in by the caller
2526 --------------------------
2527 -- Has_Controlled_Parts --
2528 --------------------------
2530 function Has_Controlled_Parts (Typ : Entity_Id) return Boolean is
2534 or else Has_Controlled_Component (Typ);
2535 end Has_Controlled_Parts;
2537 ---------------------------
2538 -- Move_Activation_Chain --
2539 ---------------------------
2541 function Move_Activation_Chain return Node_Id is
2542 Activation_Chain_Formal : constant Entity_Id :=
2543 Build_In_Place_Formal
2544 (Parent_Function, BIP_Activation_Chain);
2545 To : constant Node_Id :=
2547 (Activation_Chain_Formal, Loc);
2548 Master_Formal : constant Entity_Id :=
2549 Build_In_Place_Formal
2550 (Parent_Function, BIP_Master);
2551 New_Master : constant Node_Id :=
2552 New_Reference_To (Master_Formal, Loc);
2554 Chain_Entity : Entity_Id;
2558 Chain_Entity := First_Entity (Return_Statement_Entity (N));
2559 while Chars (Chain_Entity) /= Name_uChain loop
2560 Chain_Entity := Next_Entity (Chain_Entity);
2564 Make_Attribute_Reference (Loc,
2565 Prefix => New_Reference_To (Chain_Entity, Loc),
2566 Attribute_Name => Name_Unrestricted_Access);
2567 -- ??? Not clear why "Make_Identifier (Loc, Name_uChain)" doesn't
2568 -- work, instead of "New_Reference_To (Chain_Entity, Loc)" above.
2571 Make_Procedure_Call_Statement (Loc,
2572 Name => New_Reference_To (RTE (RE_Move_Activation_Chain), Loc),
2573 Parameter_Associations => New_List (From, To, New_Master));
2574 end Move_Activation_Chain;
2576 ---------------------
2577 -- Move_Final_List --
2578 ---------------------
2580 function Move_Final_List return Node_Id is
2581 Flist : constant Entity_Id :=
2582 Finalization_Chain_Entity (Return_Statement_Entity (N));
2584 From : constant Node_Id := New_Reference_To (Flist, Loc);
2586 Caller_Final_List : constant Entity_Id :=
2587 Build_In_Place_Formal
2588 (Parent_Function, BIP_Final_List);
2590 To : constant Node_Id := New_Reference_To (Caller_Final_List, Loc);
2593 -- Catch cases where a finalization chain entity has not been
2594 -- associated with the return statement entity.
2596 pragma Assert (Present (Flist));
2598 -- Build required call
2601 Make_If_Statement (Loc,
2604 Left_Opnd => New_Copy (From),
2605 Right_Opnd => New_Node (N_Null, Loc)),
2608 Make_Procedure_Call_Statement (Loc,
2609 Name => New_Reference_To (RTE (RE_Move_Final_List), Loc),
2610 Parameter_Associations => New_List (From, To))));
2611 end Move_Final_List;
2613 -- Start of processing for Expand_N_Extended_Return_Statement
2616 if Nkind (Return_Object_Decl) = N_Object_Declaration then
2617 Exp := Expression (Return_Object_Decl);
2622 Handled_Stm_Seq := Handled_Statement_Sequence (N);
2624 -- Build a simple_return_statement that returns the return object when
2625 -- there is a statement sequence, or no expression, or the result will
2626 -- be built in place. Note however that we currently do this for all
2627 -- composite cases, even though nonlimited composite results are not yet
2628 -- built in place (though we plan to do so eventually).
2630 if Present (Handled_Stm_Seq)
2631 or else Is_Composite_Type (Etype (Parent_Function))
2634 if No (Handled_Stm_Seq) then
2635 Statements := New_List;
2637 -- If the extended return has a handled statement sequence, then wrap
2638 -- it in a block and use the block as the first statement.
2642 New_List (Make_Block_Statement (Loc,
2643 Declarations => New_List,
2644 Handled_Statement_Sequence => Handled_Stm_Seq));
2647 -- If control gets past the above Statements, we have successfully
2648 -- completed the return statement. If the result type has controlled
2649 -- parts and the return is for a build-in-place function, then we
2650 -- call Move_Final_List to transfer responsibility for finalization
2651 -- of the return object to the caller. An alternative would be to
2652 -- declare a Success flag in the function, initialize it to False,
2653 -- and set it to True here. Then move the Move_Final_List call into
2654 -- the cleanup code, and check Success. If Success then make a call
2655 -- to Move_Final_List else do finalization. Then we can remove the
2656 -- abort-deferral and the nulling-out of the From parameter from
2657 -- Move_Final_List. Note that the current method is not quite correct
2658 -- in the rather obscure case of a select-then-abort statement whose
2659 -- abortable part contains the return statement.
2661 -- Check the type of the function to determine whether to move the
2662 -- finalization list. A special case arises when processing a simple
2663 -- return statement which has been rewritten as an extended return.
2664 -- In that case check the type of the returned object or the original
2667 if Is_Build_In_Place
2669 (Has_Controlled_Parts (Parent_Function_Typ)
2670 or else (Is_Class_Wide_Type (Parent_Function_Typ)
2672 Has_Controlled_Parts (Root_Type (Parent_Function_Typ)))
2673 or else Has_Controlled_Parts (Etype (Return_Object_Entity))
2674 or else (Present (Exp)
2675 and then Has_Controlled_Parts (Etype (Exp))))
2677 Append_To (Statements, Move_Final_List);
2680 -- Similarly to the above Move_Final_List, if the result type
2681 -- contains tasks, we call Move_Activation_Chain. Later, the cleanup
2682 -- code will call Complete_Master, which will terminate any
2683 -- unactivated tasks belonging to the return statement master. But
2684 -- Move_Activation_Chain updates their master to be that of the
2685 -- caller, so they will not be terminated unless the return statement
2686 -- completes unsuccessfully due to exception, abort, goto, or exit.
2687 -- As a formality, we test whether the function requires the result
2688 -- to be built in place, though that's necessarily true for the case
2689 -- of result types with task parts.
2691 if Is_Build_In_Place and Has_Task (Etype (Parent_Function)) then
2692 Append_To (Statements, Move_Activation_Chain);
2695 -- Build a simple_return_statement that returns the return object
2698 Make_Simple_Return_Statement (Loc,
2699 Expression => New_Occurrence_Of (Return_Object_Entity, Loc));
2700 Append_To (Statements, Return_Stm);
2703 Make_Handled_Sequence_Of_Statements (Loc, Statements);
2706 -- Case where we build a block
2708 if Present (Handled_Stm_Seq) then
2710 Make_Block_Statement (Loc,
2711 Declarations => Return_Object_Declarations (N),
2712 Handled_Statement_Sequence => Handled_Stm_Seq);
2714 -- We set the entity of the new block statement to be that of the
2715 -- return statement. This is necessary so that various fields, such
2716 -- as Finalization_Chain_Entity carry over from the return statement
2717 -- to the block. Note that this block is unusual, in that its entity
2718 -- is an E_Return_Statement rather than an E_Block.
2721 (Result, New_Occurrence_Of (Return_Statement_Entity (N), Loc));
2723 -- If the object decl was already rewritten as a renaming, then
2724 -- we don't want to do the object allocation and transformation of
2725 -- of the return object declaration to a renaming. This case occurs
2726 -- when the return object is initialized by a call to another
2727 -- build-in-place function, and that function is responsible for the
2728 -- allocation of the return object.
2730 if Is_Build_In_Place
2732 Nkind (Return_Object_Decl) = N_Object_Renaming_Declaration
2734 pragma Assert (Nkind (Original_Node (Return_Object_Decl)) =
2735 N_Object_Declaration
2736 and then Is_Build_In_Place_Function_Call
2737 (Expression (Original_Node (Return_Object_Decl))));
2739 Set_By_Ref (Return_Stm); -- Return build-in-place results by ref
2741 elsif Is_Build_In_Place then
2743 -- Locate the implicit access parameter associated with the
2744 -- caller-supplied return object and convert the return
2745 -- statement's return object declaration to a renaming of a
2746 -- dereference of the access parameter. If the return object's
2747 -- declaration includes an expression that has not already been
2748 -- expanded as separate assignments, then add an assignment
2749 -- statement to ensure the return object gets initialized.
2752 -- Result : T [:= <expression>];
2759 -- Result : T renames FuncRA.all;
2760 -- [Result := <expression;]
2765 Return_Obj_Id : constant Entity_Id :=
2766 Defining_Identifier (Return_Object_Decl);
2767 Return_Obj_Typ : constant Entity_Id := Etype (Return_Obj_Id);
2768 Return_Obj_Expr : constant Node_Id :=
2769 Expression (Return_Object_Decl);
2770 Result_Subt : constant Entity_Id :=
2771 Etype (Parent_Function);
2772 Constr_Result : constant Boolean :=
2773 Is_Constrained (Result_Subt);
2774 Obj_Alloc_Formal : Entity_Id;
2775 Object_Access : Entity_Id;
2776 Obj_Acc_Deref : Node_Id;
2777 Init_Assignment : Node_Id := Empty;
2780 -- Build-in-place results must be returned by reference
2782 Set_By_Ref (Return_Stm);
2784 -- Retrieve the implicit access parameter passed by the caller
2787 Build_In_Place_Formal (Parent_Function, BIP_Object_Access);
2789 -- If the return object's declaration includes an expression
2790 -- and the declaration isn't marked as No_Initialization, then
2791 -- we need to generate an assignment to the object and insert
2792 -- it after the declaration before rewriting it as a renaming
2793 -- (otherwise we'll lose the initialization). The case where
2794 -- the result type is an interface (or class-wide interface)
2795 -- is also excluded because the context of the function call
2796 -- must be unconstrained, so the initialization will always
2797 -- be done as part of an allocator evaluation (storage pool
2798 -- or secondary stack), never to a constrained target object
2799 -- passed in by the caller. Besides the assignment being
2800 -- unneeded in this case, it avoids problems with trying to
2801 -- generate a dispatching assignment when the return expression
2802 -- is a nonlimited descendant of a limited interface (the
2803 -- interface has no assignment operation).
2805 if Present (Return_Obj_Expr)
2806 and then not No_Initialization (Return_Object_Decl)
2807 and then not Is_Interface (Return_Obj_Typ)
2810 Make_Assignment_Statement (Loc,
2811 Name => New_Reference_To (Return_Obj_Id, Loc),
2812 Expression => Relocate_Node (Return_Obj_Expr));
2813 Set_Etype (Name (Init_Assignment), Etype (Return_Obj_Id));
2814 Set_Assignment_OK (Name (Init_Assignment));
2815 Set_No_Ctrl_Actions (Init_Assignment);
2817 Set_Parent (Name (Init_Assignment), Init_Assignment);
2818 Set_Parent (Expression (Init_Assignment), Init_Assignment);
2820 Set_Expression (Return_Object_Decl, Empty);
2822 if Is_Class_Wide_Type (Etype (Return_Obj_Id))
2823 and then not Is_Class_Wide_Type
2824 (Etype (Expression (Init_Assignment)))
2826 Rewrite (Expression (Init_Assignment),
2827 Make_Type_Conversion (Loc,
2830 (Etype (Return_Obj_Id), Loc),
2832 Relocate_Node (Expression (Init_Assignment))));
2835 -- In the case of functions where the calling context can
2836 -- determine the form of allocation needed, initialization
2837 -- is done with each part of the if statement that handles
2838 -- the different forms of allocation (this is true for
2839 -- unconstrained and tagged result subtypes).
2842 and then not Is_Tagged_Type (Underlying_Type (Result_Subt))
2844 Insert_After (Return_Object_Decl, Init_Assignment);
2848 -- When the function's subtype is unconstrained, a run-time
2849 -- test is needed to determine the form of allocation to use
2850 -- for the return object. The function has an implicit formal
2851 -- parameter indicating this. If the BIP_Alloc_Form formal has
2852 -- the value one, then the caller has passed access to an
2853 -- existing object for use as the return object. If the value
2854 -- is two, then the return object must be allocated on the
2855 -- secondary stack. Otherwise, the object must be allocated in
2856 -- a storage pool (currently only supported for the global
2857 -- heap, user-defined storage pools TBD ???). We generate an
2858 -- if statement to test the implicit allocation formal and
2859 -- initialize a local access value appropriately, creating
2860 -- allocators in the secondary stack and global heap cases.
2861 -- The special formal also exists and must be tested when the
2862 -- function has a tagged result, even when the result subtype
2863 -- is constrained, because in general such functions can be
2864 -- called in dispatching contexts and must be handled similarly
2865 -- to functions with a class-wide result.
2867 if not Constr_Result
2868 or else Is_Tagged_Type (Underlying_Type (Result_Subt))
2871 Build_In_Place_Formal (Parent_Function, BIP_Alloc_Form);
2874 Ref_Type : Entity_Id;
2875 Ptr_Type_Decl : Node_Id;
2876 Alloc_Obj_Id : Entity_Id;
2877 Alloc_Obj_Decl : Node_Id;
2878 Alloc_If_Stmt : Node_Id;
2879 SS_Allocator : Node_Id;
2880 Heap_Allocator : Node_Id;
2883 -- Reuse the itype created for the function's implicit
2884 -- access formal. This avoids the need to create a new
2885 -- access type here, plus it allows assigning the access
2886 -- formal directly without applying a conversion.
2888 -- Ref_Type := Etype (Object_Access);
2890 -- Create an access type designating the function's
2893 Ref_Type := Make_Temporary (Loc, 'A');
2896 Make_Full_Type_Declaration (Loc,
2897 Defining_Identifier => Ref_Type,
2899 Make_Access_To_Object_Definition (Loc,
2900 All_Present => True,
2901 Subtype_Indication =>
2902 New_Reference_To (Return_Obj_Typ, Loc)));
2904 Insert_Before (Return_Object_Decl, Ptr_Type_Decl);
2906 -- Create an access object that will be initialized to an
2907 -- access value denoting the return object, either coming
2908 -- from an implicit access value passed in by the caller
2909 -- or from the result of an allocator.
2911 Alloc_Obj_Id := Make_Temporary (Loc, 'R');
2912 Set_Etype (Alloc_Obj_Id, Ref_Type);
2915 Make_Object_Declaration (Loc,
2916 Defining_Identifier => Alloc_Obj_Id,
2917 Object_Definition => New_Reference_To
2920 Insert_Before (Return_Object_Decl, Alloc_Obj_Decl);
2922 -- Create allocators for both the secondary stack and
2923 -- global heap. If there's an initialization expression,
2924 -- then create these as initialized allocators.
2926 if Present (Return_Obj_Expr)
2927 and then not No_Initialization (Return_Object_Decl)
2929 -- Always use the type of the expression for the
2930 -- qualified expression, rather than the result type.
2931 -- In general we cannot always use the result type
2932 -- for the allocator, because the expression might be
2933 -- of a specific type, such as in the case of an
2934 -- aggregate or even a nonlimited object when the
2935 -- result type is a limited class-wide interface type.
2938 Make_Allocator (Loc,
2940 Make_Qualified_Expression (Loc,
2943 (Etype (Return_Obj_Expr), Loc),
2945 New_Copy_Tree (Return_Obj_Expr)));
2948 -- If the function returns a class-wide type we cannot
2949 -- use the return type for the allocator. Instead we
2950 -- use the type of the expression, which must be an
2951 -- aggregate of a definite type.
2953 if Is_Class_Wide_Type (Return_Obj_Typ) then
2955 Make_Allocator (Loc,
2958 (Etype (Return_Obj_Expr), Loc));
2961 Make_Allocator (Loc,
2963 New_Reference_To (Return_Obj_Typ, Loc));
2966 -- If the object requires default initialization then
2967 -- that will happen later following the elaboration of
2968 -- the object renaming. If we don't turn it off here
2969 -- then the object will be default initialized twice.
2971 Set_No_Initialization (Heap_Allocator);
2974 -- If the No_Allocators restriction is active, then only
2975 -- an allocator for secondary stack allocation is needed.
2976 -- It's OK for such allocators to have Comes_From_Source
2977 -- set to False, because gigi knows not to flag them as
2978 -- being a violation of No_Implicit_Heap_Allocations.
2980 if Restriction_Active (No_Allocators) then
2981 SS_Allocator := Heap_Allocator;
2982 Heap_Allocator := Make_Null (Loc);
2984 -- Otherwise the heap allocator may be needed, so we make
2985 -- another allocator for secondary stack allocation.
2988 SS_Allocator := New_Copy_Tree (Heap_Allocator);
2990 -- The heap allocator is marked Comes_From_Source
2991 -- since it corresponds to an explicit user-written
2992 -- allocator (that is, it will only be executed on
2993 -- behalf of callers that call the function as
2994 -- initialization for such an allocator). This
2995 -- prevents errors when No_Implicit_Heap_Allocations
2998 Set_Comes_From_Source (Heap_Allocator, True);
3001 -- The allocator is returned on the secondary stack. We
3002 -- don't do this on VM targets, since the SS is not used.
3004 if VM_Target = No_VM then
3005 Set_Storage_Pool (SS_Allocator, RTE (RE_SS_Pool));
3006 Set_Procedure_To_Call
3007 (SS_Allocator, RTE (RE_SS_Allocate));
3009 -- The allocator is returned on the secondary stack,
3010 -- so indicate that the function return, as well as
3011 -- the block that encloses the allocator, must not
3012 -- release it. The flags must be set now because the
3013 -- decision to use the secondary stack is done very
3014 -- late in the course of expanding the return
3015 -- statement, past the point where these flags are
3018 Set_Sec_Stack_Needed_For_Return (Parent_Function);
3019 Set_Sec_Stack_Needed_For_Return
3020 (Return_Statement_Entity (N));
3021 Set_Uses_Sec_Stack (Parent_Function);
3022 Set_Uses_Sec_Stack (Return_Statement_Entity (N));
3025 -- Create an if statement to test the BIP_Alloc_Form
3026 -- formal and initialize the access object to either the
3027 -- BIP_Object_Access formal (BIP_Alloc_Form = 0), the
3028 -- result of allocating the object in the secondary stack
3029 -- (BIP_Alloc_Form = 1), or else an allocator to create
3030 -- the return object in the heap (BIP_Alloc_Form = 2).
3032 -- ??? An unchecked type conversion must be made in the
3033 -- case of assigning the access object formal to the
3034 -- local access object, because a normal conversion would
3035 -- be illegal in some cases (such as converting access-
3036 -- to-unconstrained to access-to-constrained), but the
3037 -- the unchecked conversion will presumably fail to work
3038 -- right in just such cases. It's not clear at all how to
3042 Make_If_Statement (Loc,
3046 New_Reference_To (Obj_Alloc_Formal, Loc),
3048 Make_Integer_Literal (Loc,
3049 UI_From_Int (BIP_Allocation_Form'Pos
3050 (Caller_Allocation)))),
3052 New_List (Make_Assignment_Statement (Loc,
3055 (Alloc_Obj_Id, Loc),
3057 Make_Unchecked_Type_Conversion (Loc,
3059 New_Reference_To (Ref_Type, Loc),
3062 (Object_Access, Loc)))),
3064 New_List (Make_Elsif_Part (Loc,
3069 (Obj_Alloc_Formal, Loc),
3071 Make_Integer_Literal (Loc,
3073 BIP_Allocation_Form'Pos
3074 (Secondary_Stack)))),
3077 (Make_Assignment_Statement (Loc,
3080 (Alloc_Obj_Id, Loc),
3084 New_List (Make_Assignment_Statement (Loc,
3087 (Alloc_Obj_Id, Loc),
3091 -- If a separate initialization assignment was created
3092 -- earlier, append that following the assignment of the
3093 -- implicit access formal to the access object, to ensure
3094 -- that the return object is initialized in that case.
3095 -- In this situation, the target of the assignment must
3096 -- be rewritten to denote a dereference of the access to
3097 -- the return object passed in by the caller.
3099 if Present (Init_Assignment) then
3100 Rewrite (Name (Init_Assignment),
3101 Make_Explicit_Dereference (Loc,
3102 Prefix => New_Reference_To (Alloc_Obj_Id, Loc)));
3104 (Name (Init_Assignment), Etype (Return_Obj_Id));
3107 (Then_Statements (Alloc_If_Stmt),
3111 Insert_Before (Return_Object_Decl, Alloc_If_Stmt);
3113 -- Remember the local access object for use in the
3114 -- dereference of the renaming created below.
3116 Object_Access := Alloc_Obj_Id;
3120 -- Replace the return object declaration with a renaming of a
3121 -- dereference of the access value designating the return
3125 Make_Explicit_Dereference (Loc,
3126 Prefix => New_Reference_To (Object_Access, Loc));
3128 Rewrite (Return_Object_Decl,
3129 Make_Object_Renaming_Declaration (Loc,
3130 Defining_Identifier => Return_Obj_Id,
3131 Access_Definition => Empty,
3132 Subtype_Mark => New_Occurrence_Of
3133 (Return_Obj_Typ, Loc),
3134 Name => Obj_Acc_Deref));
3136 Set_Renamed_Object (Return_Obj_Id, Obj_Acc_Deref);
3140 -- Case where we do not build a block
3143 -- We're about to drop Return_Object_Declarations on the floor, so
3144 -- we need to insert it, in case it got expanded into useful code.
3146 Insert_List_Before (N, Return_Object_Declarations (N));
3148 -- Build simple_return_statement that returns the expression directly
3150 Return_Stm := Make_Simple_Return_Statement (Loc, Expression => Exp);
3152 Result := Return_Stm;
3155 -- Set the flag to prevent infinite recursion
3157 Set_Comes_From_Extended_Return_Statement (Return_Stm);
3159 Rewrite (N, Result);
3161 end Expand_N_Extended_Return_Statement;
3163 -----------------------------
3164 -- Expand_N_Goto_Statement --
3165 -----------------------------
3167 -- Add poll before goto if polling active
3169 procedure Expand_N_Goto_Statement (N : Node_Id) is
3171 Generate_Poll_Call (N);
3172 end Expand_N_Goto_Statement;
3174 ---------------------------
3175 -- Expand_N_If_Statement --
3176 ---------------------------
3178 -- First we deal with the case of C and Fortran convention boolean values,
3179 -- with zero/non-zero semantics.
3181 -- Second, we deal with the obvious rewriting for the cases where the
3182 -- condition of the IF is known at compile time to be True or False.
3184 -- Third, we remove elsif parts which have non-empty Condition_Actions and
3185 -- rewrite as independent if statements. For example:
3196 -- <<condition actions of y>>
3202 -- This rewriting is needed if at least one elsif part has a non-empty
3203 -- Condition_Actions list. We also do the same processing if there is a
3204 -- constant condition in an elsif part (in conjunction with the first
3205 -- processing step mentioned above, for the recursive call made to deal
3206 -- with the created inner if, this deals with properly optimizing the
3207 -- cases of constant elsif conditions).
3209 procedure Expand_N_If_Statement (N : Node_Id) is
3210 Loc : constant Source_Ptr := Sloc (N);
3215 Warn_If_Deleted : constant Boolean :=
3216 Warn_On_Deleted_Code and then Comes_From_Source (N);
3217 -- Indicates whether we want warnings when we delete branches of the
3218 -- if statement based on constant condition analysis. We never want
3219 -- these warnings for expander generated code.
3222 Adjust_Condition (Condition (N));
3224 -- The following loop deals with constant conditions for the IF. We
3225 -- need a loop because as we eliminate False conditions, we grab the
3226 -- first elsif condition and use it as the primary condition.
3228 while Compile_Time_Known_Value (Condition (N)) loop
3230 -- If condition is True, we can simply rewrite the if statement now
3231 -- by replacing it by the series of then statements.
3233 if Is_True (Expr_Value (Condition (N))) then
3235 -- All the else parts can be killed
3237 Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted);
3238 Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted);
3240 Hed := Remove_Head (Then_Statements (N));
3241 Insert_List_After (N, Then_Statements (N));
3245 -- If condition is False, then we can delete the condition and
3246 -- the Then statements
3249 -- We do not delete the condition if constant condition warnings
3250 -- are enabled, since otherwise we end up deleting the desired
3251 -- warning. Of course the backend will get rid of this True/False
3252 -- test anyway, so nothing is lost here.
3254 if not Constant_Condition_Warnings then
3255 Kill_Dead_Code (Condition (N));
3258 Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted);
3260 -- If there are no elsif statements, then we simply replace the
3261 -- entire if statement by the sequence of else statements.
3263 if No (Elsif_Parts (N)) then
3264 if No (Else_Statements (N))
3265 or else Is_Empty_List (Else_Statements (N))
3268 Make_Null_Statement (Sloc (N)));
3270 Hed := Remove_Head (Else_Statements (N));
3271 Insert_List_After (N, Else_Statements (N));
3277 -- If there are elsif statements, the first of them becomes the
3278 -- if/then section of the rebuilt if statement This is the case
3279 -- where we loop to reprocess this copied condition.
3282 Hed := Remove_Head (Elsif_Parts (N));
3283 Insert_Actions (N, Condition_Actions (Hed));
3284 Set_Condition (N, Condition (Hed));
3285 Set_Then_Statements (N, Then_Statements (Hed));
3287 -- Hed might have been captured as the condition determining
3288 -- the current value for an entity. Now it is detached from
3289 -- the tree, so a Current_Value pointer in the condition might
3290 -- need to be updated.
3292 Set_Current_Value_Condition (N);
3294 if Is_Empty_List (Elsif_Parts (N)) then
3295 Set_Elsif_Parts (N, No_List);
3301 -- Loop through elsif parts, dealing with constant conditions and
3302 -- possible expression actions that are present.
3304 if Present (Elsif_Parts (N)) then
3305 E := First (Elsif_Parts (N));
3306 while Present (E) loop
3307 Adjust_Condition (Condition (E));
3309 -- If there are condition actions, then rewrite the if statement
3310 -- as indicated above. We also do the same rewrite for a True or
3311 -- False condition. The further processing of this constant
3312 -- condition is then done by the recursive call to expand the
3313 -- newly created if statement
3315 if Present (Condition_Actions (E))
3316 or else Compile_Time_Known_Value (Condition (E))
3318 -- Note this is not an implicit if statement, since it is part
3319 -- of an explicit if statement in the source (or of an implicit
3320 -- if statement that has already been tested).
3323 Make_If_Statement (Sloc (E),
3324 Condition => Condition (E),
3325 Then_Statements => Then_Statements (E),
3326 Elsif_Parts => No_List,
3327 Else_Statements => Else_Statements (N));
3329 -- Elsif parts for new if come from remaining elsif's of parent
3331 while Present (Next (E)) loop
3332 if No (Elsif_Parts (New_If)) then
3333 Set_Elsif_Parts (New_If, New_List);
3336 Append (Remove_Next (E), Elsif_Parts (New_If));
3339 Set_Else_Statements (N, New_List (New_If));
3341 if Present (Condition_Actions (E)) then
3342 Insert_List_Before (New_If, Condition_Actions (E));
3347 if Is_Empty_List (Elsif_Parts (N)) then
3348 Set_Elsif_Parts (N, No_List);
3354 -- No special processing for that elsif part, move to next
3362 -- Some more optimizations applicable if we still have an IF statement
3364 if Nkind (N) /= N_If_Statement then
3368 -- Another optimization, special cases that can be simplified
3370 -- if expression then
3376 -- can be changed to:
3378 -- return expression;
3382 -- if expression then
3388 -- can be changed to:
3390 -- return not (expression);
3392 -- Only do these optimizations if we are at least at -O1 level and
3393 -- do not do them if control flow optimizations are suppressed.
3395 if Optimization_Level > 0
3396 and then not Opt.Suppress_Control_Flow_Optimizations
3398 if Nkind (N) = N_If_Statement
3399 and then No (Elsif_Parts (N))
3400 and then Present (Else_Statements (N))
3401 and then List_Length (Then_Statements (N)) = 1
3402 and then List_Length (Else_Statements (N)) = 1
3405 Then_Stm : constant Node_Id := First (Then_Statements (N));
3406 Else_Stm : constant Node_Id := First (Else_Statements (N));
3409 if Nkind (Then_Stm) = N_Simple_Return_Statement
3411 Nkind (Else_Stm) = N_Simple_Return_Statement
3414 Then_Expr : constant Node_Id := Expression (Then_Stm);
3415 Else_Expr : constant Node_Id := Expression (Else_Stm);
3418 if Nkind (Then_Expr) = N_Identifier
3420 Nkind (Else_Expr) = N_Identifier
3422 if Entity (Then_Expr) = Standard_True
3423 and then Entity (Else_Expr) = Standard_False
3426 Make_Simple_Return_Statement (Loc,
3427 Expression => Relocate_Node (Condition (N))));
3431 elsif Entity (Then_Expr) = Standard_False
3432 and then Entity (Else_Expr) = Standard_True
3435 Make_Simple_Return_Statement (Loc,
3439 Relocate_Node (Condition (N)))));
3449 end Expand_N_If_Statement;
3451 -----------------------------
3452 -- Expand_N_Loop_Statement --
3453 -----------------------------
3455 -- 1. Remove null loop entirely
3456 -- 2. Deal with while condition for C/Fortran boolean
3457 -- 3. Deal with loops with a non-standard enumeration type range
3458 -- 4. Deal with while loops where Condition_Actions is set
3459 -- 5. Insert polling call if required
3461 procedure Expand_N_Loop_Statement (N : Node_Id) is
3462 Loc : constant Source_Ptr := Sloc (N);
3463 Isc : constant Node_Id := Iteration_Scheme (N);
3468 if Is_Null_Loop (N) then
3469 Rewrite (N, Make_Null_Statement (Loc));
3473 -- Deal with condition for C/Fortran Boolean
3475 if Present (Isc) then
3476 Adjust_Condition (Condition (Isc));
3479 -- Generate polling call
3481 if Is_Non_Empty_List (Statements (N)) then
3482 Generate_Poll_Call (First (Statements (N)));
3485 -- Nothing more to do for plain loop with no iteration scheme
3491 -- Note: we do not have to worry about validity checking of the for loop
3492 -- range bounds here, since they were frozen with constant declarations
3493 -- and it is during that process that the validity checking is done.
3495 -- Handle the case where we have a for loop with the range type being an
3496 -- enumeration type with non-standard representation. In this case we
3499 -- for x in [reverse] a .. b loop
3505 -- for xP in [reverse] integer
3506 -- range etype'Pos (a) .. etype'Pos (b) loop
3508 -- x : constant etype := Pos_To_Rep (xP);
3514 if Present (Loop_Parameter_Specification (Isc)) then
3516 LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
3517 Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
3518 Ltype : constant Entity_Id := Etype (Loop_Id);
3519 Btype : constant Entity_Id := Base_Type (Ltype);
3524 if not Is_Enumeration_Type (Btype)
3525 or else No (Enum_Pos_To_Rep (Btype))
3531 Make_Defining_Identifier (Loc,
3532 Chars => New_External_Name (Chars (Loop_Id), 'P'));
3534 -- If the type has a contiguous representation, successive values
3535 -- can be generated as offsets from the first literal.
3537 if Has_Contiguous_Rep (Btype) then
3539 Unchecked_Convert_To (Btype,
3542 Make_Integer_Literal (Loc,
3543 Enumeration_Rep (First_Literal (Btype))),
3544 Right_Opnd => New_Reference_To (New_Id, Loc)));
3546 -- Use the constructed array Enum_Pos_To_Rep
3549 Make_Indexed_Component (Loc,
3550 Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc),
3551 Expressions => New_List (New_Reference_To (New_Id, Loc)));
3555 Make_Loop_Statement (Loc,
3556 Identifier => Identifier (N),
3559 Make_Iteration_Scheme (Loc,
3560 Loop_Parameter_Specification =>
3561 Make_Loop_Parameter_Specification (Loc,
3562 Defining_Identifier => New_Id,
3563 Reverse_Present => Reverse_Present (LPS),
3565 Discrete_Subtype_Definition =>
3566 Make_Subtype_Indication (Loc,
3569 New_Reference_To (Standard_Natural, Loc),
3572 Make_Range_Constraint (Loc,
3577 Make_Attribute_Reference (Loc,
3579 New_Reference_To (Btype, Loc),
3581 Attribute_Name => Name_Pos,
3583 Expressions => New_List (
3585 (Type_Low_Bound (Ltype)))),
3588 Make_Attribute_Reference (Loc,
3590 New_Reference_To (Btype, Loc),
3592 Attribute_Name => Name_Pos,
3594 Expressions => New_List (
3596 (Type_High_Bound (Ltype))))))))),
3598 Statements => New_List (
3599 Make_Block_Statement (Loc,
3600 Declarations => New_List (
3601 Make_Object_Declaration (Loc,
3602 Defining_Identifier => Loop_Id,
3603 Constant_Present => True,
3604 Object_Definition => New_Reference_To (Ltype, Loc),
3605 Expression => Expr)),
3607 Handled_Statement_Sequence =>
3608 Make_Handled_Sequence_Of_Statements (Loc,
3609 Statements => Statements (N)))),
3611 End_Label => End_Label (N)));
3615 -- Second case, if we have a while loop with Condition_Actions set, then
3616 -- we change it into a plain loop:
3625 -- <<condition actions>>
3631 and then Present (Condition_Actions (Isc))
3638 Make_Exit_Statement (Sloc (Condition (Isc)),
3640 Make_Op_Not (Sloc (Condition (Isc)),
3641 Right_Opnd => Condition (Isc)));
3643 Prepend (ES, Statements (N));
3644 Insert_List_Before (ES, Condition_Actions (Isc));
3646 -- This is not an implicit loop, since it is generated in response
3647 -- to the loop statement being processed. If this is itself
3648 -- implicit, the restriction has already been checked. If not,
3649 -- it is an explicit loop.
3652 Make_Loop_Statement (Sloc (N),
3653 Identifier => Identifier (N),
3654 Statements => Statements (N),
3655 End_Label => End_Label (N)));
3660 end Expand_N_Loop_Statement;
3662 --------------------------------------
3663 -- Expand_N_Simple_Return_Statement --
3664 --------------------------------------
3666 procedure Expand_N_Simple_Return_Statement (N : Node_Id) is
3668 -- Defend against previous errors (i.e. the return statement calls a
3669 -- function that is not available in configurable runtime).
3671 if Present (Expression (N))
3672 and then Nkind (Expression (N)) = N_Empty
3677 -- Distinguish the function and non-function cases:
3679 case Ekind (Return_Applies_To (Return_Statement_Entity (N))) is
3682 E_Generic_Function =>
3683 Expand_Simple_Function_Return (N);
3686 E_Generic_Procedure |
3689 E_Return_Statement =>
3690 Expand_Non_Function_Return (N);
3693 raise Program_Error;
3697 when RE_Not_Available =>
3699 end Expand_N_Simple_Return_Statement;
3701 --------------------------------
3702 -- Expand_Non_Function_Return --
3703 --------------------------------
3705 procedure Expand_Non_Function_Return (N : Node_Id) is
3706 pragma Assert (No (Expression (N)));
3708 Loc : constant Source_Ptr := Sloc (N);
3709 Scope_Id : Entity_Id :=
3710 Return_Applies_To (Return_Statement_Entity (N));
3711 Kind : constant Entity_Kind := Ekind (Scope_Id);
3714 Goto_Stat : Node_Id;
3718 -- Call _Postconditions procedure if procedure with active
3719 -- postconditions. Here, we use the Postcondition_Proc attribute, which
3720 -- is needed for implicitly-generated returns. Functions never
3721 -- have implicitly-generated returns, and there's no room for
3722 -- Postcondition_Proc in E_Function, so we look up the identifier
3723 -- Name_uPostconditions for function returns (see
3724 -- Expand_Simple_Function_Return).
3726 if Ekind (Scope_Id) = E_Procedure
3727 and then Has_Postconditions (Scope_Id)
3729 pragma Assert (Present (Postcondition_Proc (Scope_Id)));
3731 Make_Procedure_Call_Statement (Loc,
3732 Name => New_Reference_To (Postcondition_Proc (Scope_Id), Loc)));
3735 -- If it is a return from a procedure do no extra steps
3737 if Kind = E_Procedure or else Kind = E_Generic_Procedure then
3740 -- If it is a nested return within an extended one, replace it with a
3741 -- return of the previously declared return object.
3743 elsif Kind = E_Return_Statement then
3745 Make_Simple_Return_Statement (Loc,
3747 New_Occurrence_Of (First_Entity (Scope_Id), Loc)));
3748 Set_Comes_From_Extended_Return_Statement (N);
3749 Set_Return_Statement_Entity (N, Scope_Id);
3750 Expand_Simple_Function_Return (N);
3754 pragma Assert (Is_Entry (Scope_Id));
3756 -- Look at the enclosing block to see whether the return is from an
3757 -- accept statement or an entry body.
3759 for J in reverse 0 .. Scope_Stack.Last loop
3760 Scope_Id := Scope_Stack.Table (J).Entity;
3761 exit when Is_Concurrent_Type (Scope_Id);
3764 -- If it is a return from accept statement it is expanded as call to
3765 -- RTS Complete_Rendezvous and a goto to the end of the accept body.
3767 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
3768 -- Expand_N_Accept_Alternative in exp_ch9.adb)
3770 if Is_Task_Type (Scope_Id) then
3773 Make_Procedure_Call_Statement (Loc,
3774 Name => New_Reference_To (RTE (RE_Complete_Rendezvous), Loc));
3775 Insert_Before (N, Call);
3776 -- why not insert actions here???
3779 Acc_Stat := Parent (N);
3780 while Nkind (Acc_Stat) /= N_Accept_Statement loop
3781 Acc_Stat := Parent (Acc_Stat);
3784 Lab_Node := Last (Statements
3785 (Handled_Statement_Sequence (Acc_Stat)));
3787 Goto_Stat := Make_Goto_Statement (Loc,
3788 Name => New_Occurrence_Of
3789 (Entity (Identifier (Lab_Node)), Loc));
3791 Set_Analyzed (Goto_Stat);
3793 Rewrite (N, Goto_Stat);
3796 -- If it is a return from an entry body, put a Complete_Entry_Body call
3797 -- in front of the return.
3799 elsif Is_Protected_Type (Scope_Id) then
3801 Make_Procedure_Call_Statement (Loc,
3803 New_Reference_To (RTE (RE_Complete_Entry_Body), Loc),
3804 Parameter_Associations => New_List (
3805 Make_Attribute_Reference (Loc,
3808 (Find_Protection_Object (Current_Scope), Loc),
3810 Name_Unchecked_Access)));
3812 Insert_Before (N, Call);
3815 end Expand_Non_Function_Return;
3817 -----------------------------------
3818 -- Expand_Simple_Function_Return --
3819 -----------------------------------
3821 -- The "simple" comes from the syntax rule simple_return_statement.
3822 -- The semantics are not at all simple!
3824 procedure Expand_Simple_Function_Return (N : Node_Id) is
3825 Loc : constant Source_Ptr := Sloc (N);
3827 Scope_Id : constant Entity_Id :=
3828 Return_Applies_To (Return_Statement_Entity (N));
3829 -- The function we are returning from
3831 R_Type : constant Entity_Id := Etype (Scope_Id);
3832 -- The result type of the function
3834 Utyp : constant Entity_Id := Underlying_Type (R_Type);
3836 Exp : constant Node_Id := Expression (N);
3837 pragma Assert (Present (Exp));
3839 Exptyp : constant Entity_Id := Etype (Exp);
3840 -- The type of the expression (not necessarily the same as R_Type)
3842 Subtype_Ind : Node_Id;
3843 -- If the result type of the function is class-wide and the
3844 -- expression has a specific type, then we use the expression's
3845 -- type as the type of the return object. In cases where the
3846 -- expression is an aggregate that is built in place, this avoids
3847 -- the need for an expensive conversion of the return object to
3848 -- the specific type on assignments to the individual components.
3851 if Is_Class_Wide_Type (R_Type)
3852 and then not Is_Class_Wide_Type (Etype (Exp))
3854 Subtype_Ind := New_Occurrence_Of (Etype (Exp), Loc);
3856 Subtype_Ind := New_Occurrence_Of (R_Type, Loc);
3859 -- For the case of a simple return that does not come from an extended
3860 -- return, in the case of Ada 2005 where we are returning a limited
3861 -- type, we rewrite "return <expression>;" to be:
3863 -- return _anon_ : <return_subtype> := <expression>
3865 -- The expansion produced by Expand_N_Extended_Return_Statement will
3866 -- contain simple return statements (for example, a block containing
3867 -- simple return of the return object), which brings us back here with
3868 -- Comes_From_Extended_Return_Statement set. The reason for the barrier
3869 -- checking for a simple return that does not come from an extended
3870 -- return is to avoid this infinite recursion.
3872 -- The reason for this design is that for Ada 2005 limited returns, we
3873 -- need to reify the return object, so we can build it "in place", and
3874 -- we need a block statement to hang finalization and tasking stuff.
3876 -- ??? In order to avoid disruption, we avoid translating to extended
3877 -- return except in the cases where we really need to (Ada 2005 for
3878 -- inherently limited). We might prefer to do this translation in all
3879 -- cases (except perhaps for the case of Ada 95 inherently limited),
3880 -- in order to fully exercise the Expand_N_Extended_Return_Statement
3881 -- code. This would also allow us to do the build-in-place optimization
3882 -- for efficiency even in cases where it is semantically not required.
3884 -- As before, we check the type of the return expression rather than the
3885 -- return type of the function, because the latter may be a limited
3886 -- class-wide interface type, which is not a limited type, even though
3887 -- the type of the expression may be.
3889 if not Comes_From_Extended_Return_Statement (N)
3890 and then Is_Inherently_Limited_Type (Etype (Expression (N)))
3891 and then Ada_Version >= Ada_05
3892 and then not Debug_Flag_Dot_L
3895 Return_Object_Entity : constant Entity_Id :=
3896 Make_Temporary (Loc, 'R', Exp);
3897 Obj_Decl : constant Node_Id :=
3898 Make_Object_Declaration (Loc,
3899 Defining_Identifier => Return_Object_Entity,
3900 Object_Definition => Subtype_Ind,
3903 Ext : constant Node_Id := Make_Extended_Return_Statement (Loc,
3904 Return_Object_Declarations => New_List (Obj_Decl));
3905 -- Do not perform this high-level optimization if the result type
3906 -- is an interface because the "this" pointer must be displaced.
3915 -- Here we have a simple return statement that is part of the expansion
3916 -- of an extended return statement (either written by the user, or
3917 -- generated by the above code).
3919 -- Always normalize C/Fortran boolean result. This is not always needed,
3920 -- but it seems a good idea to minimize the passing around of non-
3921 -- normalized values, and in any case this handles the processing of
3922 -- barrier functions for protected types, which turn the condition into
3923 -- a return statement.
3925 if Is_Boolean_Type (Exptyp)
3926 and then Nonzero_Is_True (Exptyp)
3928 Adjust_Condition (Exp);
3929 Adjust_Result_Type (Exp, Exptyp);
3932 -- Do validity check if enabled for returns
3934 if Validity_Checks_On
3935 and then Validity_Check_Returns
3940 -- Check the result expression of a scalar function against the subtype
3941 -- of the function by inserting a conversion. This conversion must
3942 -- eventually be performed for other classes of types, but for now it's
3943 -- only done for scalars.
3946 if Is_Scalar_Type (Exptyp) then
3947 Rewrite (Exp, Convert_To (R_Type, Exp));
3949 -- The expression is resolved to ensure that the conversion gets
3950 -- expanded to generate a possible constraint check.
3952 Analyze_And_Resolve (Exp, R_Type);
3955 -- Deal with returning variable length objects and controlled types
3957 -- Nothing to do if we are returning by reference, or this is not a
3958 -- type that requires special processing (indicated by the fact that
3959 -- it requires a cleanup scope for the secondary stack case).
3961 if Is_Inherently_Limited_Type (Exptyp)
3962 or else Is_Limited_Interface (Exptyp)
3966 elsif not Requires_Transient_Scope (R_Type) then
3968 -- Mutable records with no variable length components are not
3969 -- returned on the sec-stack, so we need to make sure that the
3970 -- backend will only copy back the size of the actual value, and not
3971 -- the maximum size. We create an actual subtype for this purpose.
3974 Ubt : constant Entity_Id := Underlying_Type (Base_Type (Exptyp));
3978 if Has_Discriminants (Ubt)
3979 and then not Is_Constrained (Ubt)
3980 and then not Has_Unchecked_Union (Ubt)
3982 Decl := Build_Actual_Subtype (Ubt, Exp);
3983 Ent := Defining_Identifier (Decl);
3984 Insert_Action (Exp, Decl);
3985 Rewrite (Exp, Unchecked_Convert_To (Ent, Exp));
3986 Analyze_And_Resolve (Exp);
3990 -- Here if secondary stack is used
3993 -- Make sure that no surrounding block will reclaim the secondary
3994 -- stack on which we are going to put the result. Not only may this
3995 -- introduce secondary stack leaks but worse, if the reclamation is
3996 -- done too early, then the result we are returning may get
4003 while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop
4004 Set_Sec_Stack_Needed_For_Return (S, True);
4005 S := Enclosing_Dynamic_Scope (S);
4009 -- Optimize the case where the result is a function call. In this
4010 -- case either the result is already on the secondary stack, or is
4011 -- already being returned with the stack pointer depressed and no
4012 -- further processing is required except to set the By_Ref flag to
4013 -- ensure that gigi does not attempt an extra unnecessary copy.
4014 -- (actually not just unnecessary but harmfully wrong in the case
4015 -- of a controlled type, where gigi does not know how to do a copy).
4016 -- To make up for a gcc 2.8.1 deficiency (???), we perform
4017 -- the copy for array types if the constrained status of the
4018 -- target type is different from that of the expression.
4020 if Requires_Transient_Scope (Exptyp)
4022 (not Is_Array_Type (Exptyp)
4023 or else Is_Constrained (Exptyp) = Is_Constrained (R_Type)
4024 or else CW_Or_Has_Controlled_Part (Utyp))
4025 and then Nkind (Exp) = N_Function_Call
4029 -- Remove side effects from the expression now so that other parts
4030 -- of the expander do not have to reanalyze this node without this
4033 Rewrite (Exp, Duplicate_Subexpr_No_Checks (Exp));
4035 -- For controlled types, do the allocation on the secondary stack
4036 -- manually in order to call adjust at the right time:
4038 -- type Anon1 is access R_Type;
4039 -- for Anon1'Storage_pool use ss_pool;
4040 -- Anon2 : anon1 := new R_Type'(expr);
4041 -- return Anon2.all;
4043 -- We do the same for classwide types that are not potentially
4044 -- controlled (by the virtue of restriction No_Finalization) because
4045 -- gigi is not able to properly allocate class-wide types.
4047 elsif CW_Or_Has_Controlled_Part (Utyp) then
4049 Loc : constant Source_Ptr := Sloc (N);
4050 Acc_Typ : constant Entity_Id := Make_Temporary (Loc, 'A');
4051 Alloc_Node : Node_Id;
4055 Set_Ekind (Acc_Typ, E_Access_Type);
4057 Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool));
4059 -- This is an allocator for the secondary stack, and it's fine
4060 -- to have Comes_From_Source set False on it, as gigi knows not
4061 -- to flag it as a violation of No_Implicit_Heap_Allocations.
4064 Make_Allocator (Loc,
4066 Make_Qualified_Expression (Loc,
4067 Subtype_Mark => New_Reference_To (Etype (Exp), Loc),
4068 Expression => Relocate_Node (Exp)));
4070 -- We do not want discriminant checks on the declaration,
4071 -- given that it gets its value from the allocator.
4073 Set_No_Initialization (Alloc_Node);
4075 Temp := Make_Temporary (Loc, 'R', Alloc_Node);
4077 Insert_List_Before_And_Analyze (N, New_List (
4078 Make_Full_Type_Declaration (Loc,
4079 Defining_Identifier => Acc_Typ,
4081 Make_Access_To_Object_Definition (Loc,
4082 Subtype_Indication => Subtype_Ind)),
4084 Make_Object_Declaration (Loc,
4085 Defining_Identifier => Temp,
4086 Object_Definition => New_Reference_To (Acc_Typ, Loc),
4087 Expression => Alloc_Node)));
4090 Make_Explicit_Dereference (Loc,
4091 Prefix => New_Reference_To (Temp, Loc)));
4093 Analyze_And_Resolve (Exp, R_Type);
4096 -- Otherwise use the gigi mechanism to allocate result on the
4100 Check_Restriction (No_Secondary_Stack, N);
4101 Set_Storage_Pool (N, RTE (RE_SS_Pool));
4103 -- If we are generating code for the VM do not use
4104 -- SS_Allocate since everything is heap-allocated anyway.
4106 if VM_Target = No_VM then
4107 Set_Procedure_To_Call (N, RTE (RE_SS_Allocate));
4112 -- Implement the rules of 6.5(8-10), which require a tag check in the
4113 -- case of a limited tagged return type, and tag reassignment for
4114 -- nonlimited tagged results. These actions are needed when the return
4115 -- type is a specific tagged type and the result expression is a
4116 -- conversion or a formal parameter, because in that case the tag of the
4117 -- expression might differ from the tag of the specific result type.
4119 if Is_Tagged_Type (Utyp)
4120 and then not Is_Class_Wide_Type (Utyp)
4121 and then (Nkind_In (Exp, N_Type_Conversion,
4122 N_Unchecked_Type_Conversion)
4123 or else (Is_Entity_Name (Exp)
4124 and then Ekind (Entity (Exp)) in Formal_Kind))
4126 -- When the return type is limited, perform a check that the
4127 -- tag of the result is the same as the tag of the return type.
4129 if Is_Limited_Type (R_Type) then
4131 Make_Raise_Constraint_Error (Loc,
4135 Make_Selected_Component (Loc,
4136 Prefix => Duplicate_Subexpr (Exp),
4138 New_Reference_To (First_Tag_Component (Utyp), Loc)),
4140 Unchecked_Convert_To (RTE (RE_Tag),
4143 (Access_Disp_Table (Base_Type (Utyp)))),
4145 Reason => CE_Tag_Check_Failed));
4147 -- If the result type is a specific nonlimited tagged type, then we
4148 -- have to ensure that the tag of the result is that of the result
4149 -- type. This is handled by making a copy of the expression in the
4150 -- case where it might have a different tag, namely when the
4151 -- expression is a conversion or a formal parameter. We create a new
4152 -- object of the result type and initialize it from the expression,
4153 -- which will implicitly force the tag to be set appropriately.
4157 ExpR : constant Node_Id := Relocate_Node (Exp);
4158 Result_Id : constant Entity_Id :=
4159 Make_Temporary (Loc, 'R', ExpR);
4160 Result_Exp : constant Node_Id :=
4161 New_Reference_To (Result_Id, Loc);
4162 Result_Obj : constant Node_Id :=
4163 Make_Object_Declaration (Loc,
4164 Defining_Identifier => Result_Id,
4165 Object_Definition =>
4166 New_Reference_To (R_Type, Loc),
4167 Constant_Present => True,
4168 Expression => ExpR);
4171 Set_Assignment_OK (Result_Obj);
4172 Insert_Action (Exp, Result_Obj);
4174 Rewrite (Exp, Result_Exp);
4175 Analyze_And_Resolve (Exp, R_Type);
4179 -- Ada 2005 (AI-344): If the result type is class-wide, then insert
4180 -- a check that the level of the return expression's underlying type
4181 -- is not deeper than the level of the master enclosing the function.
4182 -- Always generate the check when the type of the return expression
4183 -- is class-wide, when it's a type conversion, or when it's a formal
4184 -- parameter. Otherwise, suppress the check in the case where the
4185 -- return expression has a specific type whose level is known not to
4186 -- be statically deeper than the function's result type.
4188 -- Note: accessibility check is skipped in the VM case, since there
4189 -- does not seem to be any practical way to implement this check.
4191 elsif Ada_Version >= Ada_05
4192 and then Tagged_Type_Expansion
4193 and then Is_Class_Wide_Type (R_Type)
4194 and then not Scope_Suppress (Accessibility_Check)
4196 (Is_Class_Wide_Type (Etype (Exp))
4197 or else Nkind_In (Exp, N_Type_Conversion,
4198 N_Unchecked_Type_Conversion)
4199 or else (Is_Entity_Name (Exp)
4200 and then Ekind (Entity (Exp)) in Formal_Kind)
4201 or else Scope_Depth (Enclosing_Dynamic_Scope (Etype (Exp))) >
4202 Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))
4208 -- Ada 2005 (AI-251): In class-wide interface objects we displace
4209 -- "this" to reference the base of the object --- required to get
4210 -- access to the TSD of the object.
4212 if Is_Class_Wide_Type (Etype (Exp))
4213 and then Is_Interface (Etype (Exp))
4214 and then Nkind (Exp) = N_Explicit_Dereference
4217 Make_Explicit_Dereference (Loc,
4218 Unchecked_Convert_To (RTE (RE_Tag_Ptr),
4219 Make_Function_Call (Loc,
4220 Name => New_Reference_To (RTE (RE_Base_Address), Loc),
4221 Parameter_Associations => New_List (
4222 Unchecked_Convert_To (RTE (RE_Address),
4223 Duplicate_Subexpr (Prefix (Exp)))))));
4226 Make_Attribute_Reference (Loc,
4227 Prefix => Duplicate_Subexpr (Exp),
4228 Attribute_Name => Name_Tag);
4232 Make_Raise_Program_Error (Loc,
4236 Build_Get_Access_Level (Loc, Tag_Node),
4238 Make_Integer_Literal (Loc,
4239 Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))),
4240 Reason => PE_Accessibility_Check_Failed));
4244 -- If we are returning an object that may not be bit-aligned, then copy
4245 -- the value into a temporary first. This copy may need to expand to a
4246 -- loop of component operations.
4248 if Is_Possibly_Unaligned_Slice (Exp)
4249 or else Is_Possibly_Unaligned_Object (Exp)
4252 ExpR : constant Node_Id := Relocate_Node (Exp);
4253 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', ExpR);
4256 Make_Object_Declaration (Loc,
4257 Defining_Identifier => Tnn,
4258 Constant_Present => True,
4259 Object_Definition => New_Occurrence_Of (R_Type, Loc),
4260 Expression => ExpR),
4261 Suppress => All_Checks);
4262 Rewrite (Exp, New_Occurrence_Of (Tnn, Loc));
4266 -- Generate call to postcondition checks if they are present
4268 if Ekind (Scope_Id) = E_Function
4269 and then Has_Postconditions (Scope_Id)
4271 -- We are going to reference the returned value twice in this case,
4272 -- once in the call to _Postconditions, and once in the actual return
4273 -- statement, but we can't have side effects happening twice, and in
4274 -- any case for efficiency we don't want to do the computation twice.
4276 -- If the returned expression is an entity name, we don't need to
4277 -- worry since it is efficient and safe to reference it twice, that's
4278 -- also true for literals other than string literals, and for the
4279 -- case of X.all where X is an entity name.
4281 if Is_Entity_Name (Exp)
4282 or else Nkind_In (Exp, N_Character_Literal,
4285 or else (Nkind (Exp) = N_Explicit_Dereference
4286 and then Is_Entity_Name (Prefix (Exp)))
4290 -- Otherwise we are going to need a temporary to capture the value
4294 ExpR : constant Node_Id := Relocate_Node (Exp);
4295 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', ExpR);
4298 -- For a complex expression of an elementary type, capture
4299 -- value in the temporary and use it as the reference.
4301 if Is_Elementary_Type (R_Type) then
4303 Make_Object_Declaration (Loc,
4304 Defining_Identifier => Tnn,
4305 Constant_Present => True,
4306 Object_Definition => New_Occurrence_Of (R_Type, Loc),
4307 Expression => ExpR),
4308 Suppress => All_Checks);
4310 Rewrite (Exp, New_Occurrence_Of (Tnn, Loc));
4312 -- If we have something we can rename, generate a renaming of
4313 -- the object and replace the expression with a reference
4315 elsif Is_Object_Reference (Exp) then
4317 Make_Object_Renaming_Declaration (Loc,
4318 Defining_Identifier => Tnn,
4319 Subtype_Mark => New_Occurrence_Of (R_Type, Loc),
4321 Suppress => All_Checks);
4323 Rewrite (Exp, New_Occurrence_Of (Tnn, Loc));
4325 -- Otherwise we have something like a string literal or an
4326 -- aggregate. We could copy the value, but that would be
4327 -- inefficient. Instead we make a reference to the value and
4328 -- capture this reference with a renaming, the expression is
4329 -- then replaced by a dereference of this renaming.
4332 -- For now, copy the value, since the code below does not
4333 -- seem to work correctly ???
4336 Make_Object_Declaration (Loc,
4337 Defining_Identifier => Tnn,
4338 Constant_Present => True,
4339 Object_Definition => New_Occurrence_Of (R_Type, Loc),
4340 Expression => Relocate_Node (Exp)),
4341 Suppress => All_Checks);
4343 Rewrite (Exp, New_Occurrence_Of (Tnn, Loc));
4345 -- Insert_Action (Exp,
4346 -- Make_Object_Renaming_Declaration (Loc,
4347 -- Defining_Identifier => Tnn,
4348 -- Access_Definition =>
4349 -- Make_Access_Definition (Loc,
4350 -- All_Present => True,
4351 -- Subtype_Mark => New_Occurrence_Of (R_Type, Loc)),
4353 -- Make_Reference (Loc,
4354 -- Prefix => Relocate_Node (Exp))),
4355 -- Suppress => All_Checks);
4358 -- Make_Explicit_Dereference (Loc,
4359 -- Prefix => New_Occurrence_Of (Tnn, Loc)));
4364 -- Generate call to _postconditions
4367 Make_Procedure_Call_Statement (Loc,
4368 Name => Make_Identifier (Loc, Name_uPostconditions),
4369 Parameter_Associations => New_List (Duplicate_Subexpr (Exp))));
4372 -- Ada 2005 (AI-251): If this return statement corresponds with an
4373 -- simple return statement associated with an extended return statement
4374 -- and the type of the returned object is an interface then generate an
4375 -- implicit conversion to force displacement of the "this" pointer.
4377 if Ada_Version >= Ada_05
4378 and then Comes_From_Extended_Return_Statement (N)
4379 and then Nkind (Expression (N)) = N_Identifier
4380 and then Is_Interface (Utyp)
4381 and then Utyp /= Underlying_Type (Exptyp)
4383 Rewrite (Exp, Convert_To (Utyp, Relocate_Node (Exp)));
4384 Analyze_And_Resolve (Exp);
4386 end Expand_Simple_Function_Return;
4388 ------------------------------
4389 -- Make_Tag_Ctrl_Assignment --
4390 ------------------------------
4392 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is
4393 Loc : constant Source_Ptr := Sloc (N);
4394 L : constant Node_Id := Name (N);
4395 T : constant Entity_Id := Underlying_Type (Etype (L));
4397 Ctrl_Act : constant Boolean := Needs_Finalization (T)
4398 and then not No_Ctrl_Actions (N);
4400 Component_Assign : constant Boolean :=
4401 Is_Fully_Repped_Tagged_Type (T);
4403 Save_Tag : constant Boolean := Is_Tagged_Type (T)
4404 and then not Component_Assign
4405 and then not No_Ctrl_Actions (N)
4406 and then Tagged_Type_Expansion;
4407 -- Tags are not saved and restored when VM_Target because VM tags are
4408 -- represented implicitly in objects.
4411 Tag_Tmp : Entity_Id;
4413 Prev_Tmp : Entity_Id;
4414 Next_Tmp : Entity_Id;
4420 -- Finalize the target of the assignment when controlled
4422 -- We have two exceptions here:
4424 -- 1. If we are in an init proc since it is an initialization more
4425 -- than an assignment.
4427 -- 2. If the left-hand side is a temporary that was not initialized
4428 -- (or the parent part of a temporary since it is the case in
4429 -- extension aggregates). Such a temporary does not come from
4430 -- source. We must examine the original node for the prefix, because
4431 -- it may be a component of an entry formal, in which case it has
4432 -- been rewritten and does not appear to come from source either.
4434 -- Case of init proc
4436 if not Ctrl_Act then
4439 -- The left hand side is an uninitialized temporary object
4441 elsif Nkind (L) = N_Type_Conversion
4442 and then Is_Entity_Name (Expression (L))
4443 and then Nkind (Parent (Entity (Expression (L)))) =
4444 N_Object_Declaration
4445 and then No_Initialization (Parent (Entity (Expression (L))))
4450 Append_List_To (Res,
4452 (Ref => Duplicate_Subexpr_No_Checks (L),
4454 With_Detach => New_Reference_To (Standard_False, Loc)));
4457 -- Save the Tag in a local variable Tag_Tmp
4460 Tag_Tmp := Make_Temporary (Loc, 'A');
4463 Make_Object_Declaration (Loc,
4464 Defining_Identifier => Tag_Tmp,
4465 Object_Definition => New_Reference_To (RTE (RE_Tag), Loc),
4467 Make_Selected_Component (Loc,
4468 Prefix => Duplicate_Subexpr_No_Checks (L),
4469 Selector_Name => New_Reference_To (First_Tag_Component (T),
4472 -- Otherwise Tag_Tmp not used
4479 if VM_Target /= No_VM then
4481 -- Cannot assign part of the object in a VM context, so instead
4482 -- fallback to the previous mechanism, even though it is not
4483 -- completely correct ???
4485 -- Save the Finalization Pointers in local variables Prev_Tmp and
4486 -- Next_Tmp. For objects with Has_Controlled_Component set, these
4487 -- pointers are in the Record_Controller
4489 Ctrl_Ref := Duplicate_Subexpr (L);
4491 if Has_Controlled_Component (T) then
4493 Make_Selected_Component (Loc,
4496 New_Reference_To (Controller_Component (T), Loc));
4499 Prev_Tmp := Make_Temporary (Loc, 'B');
4502 Make_Object_Declaration (Loc,
4503 Defining_Identifier => Prev_Tmp,
4505 Object_Definition =>
4506 New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
4509 Make_Selected_Component (Loc,
4511 Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref),
4512 Selector_Name => Make_Identifier (Loc, Name_Prev))));
4514 Next_Tmp := Make_Temporary (Loc, 'C');
4517 Make_Object_Declaration (Loc,
4518 Defining_Identifier => Next_Tmp,
4520 Object_Definition =>
4521 New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
4524 Make_Selected_Component (Loc,
4526 Unchecked_Convert_To (RTE (RE_Finalizable),
4527 New_Copy_Tree (Ctrl_Ref)),
4528 Selector_Name => Make_Identifier (Loc, Name_Next))));
4530 -- Do the Assignment
4532 Append_To (Res, Relocate_Node (N));
4535 -- Regular (non VM) processing for controlled types and types with
4536 -- controlled components
4538 -- Variables of such types contain pointers used to chain them in
4539 -- finalization lists, in addition to user data. These pointers
4540 -- are specific to each object of the type, not to the value being
4543 -- Thus they need to be left intact during the assignment. We
4544 -- achieve this by constructing a Storage_Array subtype, and by
4545 -- overlaying objects of this type on the source and target of the
4546 -- assignment. The assignment is then rewritten to assignments of
4547 -- slices of these arrays, copying the user data, and leaving the
4548 -- pointers untouched.
4550 Controlled_Actions : declare
4552 -- A reference to the Prev component of the record controller
4554 First_After_Root : Node_Id := Empty;
4555 -- Index of first byte to be copied (used to skip
4556 -- Root_Controlled in controlled objects).
4558 Last_Before_Hole : Node_Id := Empty;
4559 -- Index of last byte to be copied before outermost record
4562 Hole_Length : Node_Id := Empty;
4563 -- Length of record controller data (Prev and Next pointers)
4565 First_After_Hole : Node_Id := Empty;
4566 -- Index of first byte to be copied after outermost record
4569 Expr, Source_Size : Node_Id;
4570 Source_Actual_Subtype : Entity_Id;
4571 -- Used for computation of the size of the data to be copied
4573 Range_Type : Entity_Id;
4574 Opaque_Type : Entity_Id;
4576 function Build_Slice
4579 Hi : Node_Id) return Node_Id;
4580 -- Build and return a slice of an array of type S overlaid on
4581 -- object Rec, with bounds specified by Lo and Hi. If either
4582 -- bound is empty, a default of S'First (respectively S'Last)
4589 function Build_Slice
4592 Hi : Node_Id) return Node_Id
4597 Opaque : constant Node_Id :=
4598 Unchecked_Convert_To (Opaque_Type,
4599 Make_Attribute_Reference (Loc,
4601 Attribute_Name => Name_Address));
4602 -- Access value designating an opaque storage array of type
4603 -- S overlaid on record Rec.
4606 -- Compute slice bounds using S'First (1) and S'Last as
4607 -- default values when not specified by the caller.
4610 Lo_Bound := Make_Integer_Literal (Loc, 1);
4616 Hi_Bound := Make_Attribute_Reference (Loc,
4617 Prefix => New_Occurrence_Of (Range_Type, Loc),
4618 Attribute_Name => Name_Last);
4623 return Make_Slice (Loc,
4626 Discrete_Range => Make_Range (Loc,
4627 Lo_Bound, Hi_Bound));
4630 -- Start of processing for Controlled_Actions
4633 -- Create a constrained subtype of Storage_Array whose size
4634 -- corresponds to the value being assigned.
4636 -- subtype G is Storage_Offset range
4637 -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit
4639 Expr := Duplicate_Subexpr_No_Checks (Expression (N));
4641 if Nkind (Expr) = N_Qualified_Expression then
4642 Expr := Expression (Expr);
4645 Source_Actual_Subtype := Etype (Expr);
4647 if Has_Discriminants (Source_Actual_Subtype)
4648 and then not Is_Constrained (Source_Actual_Subtype)
4651 Build_Actual_Subtype (Source_Actual_Subtype, Expr));
4652 Source_Actual_Subtype := Defining_Identifier (Last (Res));
4658 Make_Attribute_Reference (Loc,
4660 New_Occurrence_Of (Source_Actual_Subtype, Loc),
4661 Attribute_Name => Name_Size),
4663 Make_Integer_Literal (Loc,
4664 Intval => System_Storage_Unit - 1));
4667 Make_Op_Divide (Loc,
4668 Left_Opnd => Source_Size,
4670 Make_Integer_Literal (Loc,
4671 Intval => System_Storage_Unit));
4673 Range_Type := Make_Temporary (Loc, 'G');
4676 Make_Subtype_Declaration (Loc,
4677 Defining_Identifier => Range_Type,
4678 Subtype_Indication =>
4679 Make_Subtype_Indication (Loc,
4681 New_Reference_To (RTE (RE_Storage_Offset), Loc),
4682 Constraint => Make_Range_Constraint (Loc,
4685 Low_Bound => Make_Integer_Literal (Loc, 1),
4686 High_Bound => Source_Size)))));
4688 -- subtype S is Storage_Array (G)
4691 Make_Subtype_Declaration (Loc,
4692 Defining_Identifier => Make_Temporary (Loc, 'S'),
4693 Subtype_Indication =>
4694 Make_Subtype_Indication (Loc,
4696 New_Reference_To (RTE (RE_Storage_Array), Loc),
4698 Make_Index_Or_Discriminant_Constraint (Loc,
4700 New_List (New_Reference_To (Range_Type, Loc))))));
4702 -- type A is access S
4704 Opaque_Type := Make_Temporary (Loc, 'A');
4707 Make_Full_Type_Declaration (Loc,
4708 Defining_Identifier => Opaque_Type,
4710 Make_Access_To_Object_Definition (Loc,
4711 Subtype_Indication =>
4713 Defining_Identifier (Last (Res)), Loc))));
4715 -- Generate appropriate slice assignments
4717 First_After_Root := Make_Integer_Literal (Loc, 1);
4719 -- For controlled object, skip Root_Controlled part
4721 if Is_Controlled (T) then
4725 Make_Op_Divide (Loc,
4726 Make_Attribute_Reference (Loc,
4728 New_Occurrence_Of (RTE (RE_Root_Controlled), Loc),
4729 Attribute_Name => Name_Size),
4730 Make_Integer_Literal (Loc, System_Storage_Unit)));
4733 -- For the case of a record with controlled components, skip
4734 -- record controller Prev/Next components. These components
4735 -- constitute a 'hole' in the middle of the data to be copied.
4737 if Has_Controlled_Component (T) then
4739 Make_Selected_Component (Loc,
4741 Make_Selected_Component (Loc,
4742 Prefix => Duplicate_Subexpr_No_Checks (L),
4744 New_Reference_To (Controller_Component (T), Loc)),
4745 Selector_Name => Make_Identifier (Loc, Name_Prev));
4747 -- Last index before hole: determined by position of the
4748 -- _Controller.Prev component.
4750 Last_Before_Hole := Make_Temporary (Loc, 'L');
4753 Make_Object_Declaration (Loc,
4754 Defining_Identifier => Last_Before_Hole,
4755 Object_Definition => New_Occurrence_Of (
4756 RTE (RE_Storage_Offset), Loc),
4757 Constant_Present => True,
4760 Make_Attribute_Reference (Loc,
4762 Attribute_Name => Name_Position),
4763 Make_Attribute_Reference (Loc,
4764 Prefix => New_Copy_Tree (Prefix (Prev_Ref)),
4765 Attribute_Name => Name_Position))));
4767 -- Hole length: size of the Prev and Next components
4770 Make_Op_Multiply (Loc,
4771 Left_Opnd => Make_Integer_Literal (Loc, Uint_2),
4773 Make_Op_Divide (Loc,
4775 Make_Attribute_Reference (Loc,
4776 Prefix => New_Copy_Tree (Prev_Ref),
4777 Attribute_Name => Name_Size),
4779 Make_Integer_Literal (Loc,
4780 Intval => System_Storage_Unit)));
4782 -- First index after hole
4784 First_After_Hole := Make_Temporary (Loc, 'F');
4787 Make_Object_Declaration (Loc,
4788 Defining_Identifier => First_After_Hole,
4789 Object_Definition => New_Occurrence_Of (
4790 RTE (RE_Storage_Offset), Loc),
4791 Constant_Present => True,
4797 New_Occurrence_Of (Last_Before_Hole, Loc),
4798 Right_Opnd => Hole_Length),
4799 Right_Opnd => Make_Integer_Literal (Loc, 1))));
4802 New_Occurrence_Of (Last_Before_Hole, Loc);
4804 New_Occurrence_Of (First_After_Hole, Loc);
4807 -- Assign the first slice (possibly skipping Root_Controlled,
4808 -- up to the beginning of the record controller if present,
4809 -- up to the end of the object if not).
4811 Append_To (Res, Make_Assignment_Statement (Loc,
4812 Name => Build_Slice (
4813 Rec => Duplicate_Subexpr_No_Checks (L),
4814 Lo => First_After_Root,
4815 Hi => Last_Before_Hole),
4817 Expression => Build_Slice (
4818 Rec => Expression (N),
4819 Lo => First_After_Root,
4820 Hi => New_Copy_Tree (Last_Before_Hole))));
4822 if Present (First_After_Hole) then
4824 -- If a record controller is present, copy the second slice,
4825 -- from right after the _Controller.Next component up to the
4826 -- end of the object.
4828 Append_To (Res, Make_Assignment_Statement (Loc,
4829 Name => Build_Slice (
4830 Rec => Duplicate_Subexpr_No_Checks (L),
4831 Lo => First_After_Hole,
4833 Expression => Build_Slice (
4834 Rec => Duplicate_Subexpr_No_Checks (Expression (N)),
4835 Lo => New_Copy_Tree (First_After_Hole),
4838 end Controlled_Actions;
4841 -- Not controlled case
4845 Asn : constant Node_Id := Relocate_Node (N);
4848 -- If this is the case of a tagged type with a full rep clause,
4849 -- we must expand it into component assignments, so we mark the
4850 -- node as unanalyzed, to get it reanalyzed, but flag it has
4851 -- requiring component-wise assignment so we don't get infinite
4854 if Component_Assign then
4855 Set_Analyzed (Asn, False);
4856 Set_Componentwise_Assignment (Asn, True);
4859 Append_To (Res, Asn);
4867 Make_Assignment_Statement (Loc,
4869 Make_Selected_Component (Loc,
4870 Prefix => Duplicate_Subexpr_No_Checks (L),
4871 Selector_Name => New_Reference_To (First_Tag_Component (T),
4873 Expression => New_Reference_To (Tag_Tmp, Loc)));
4877 if VM_Target /= No_VM then
4878 -- Restore the finalization pointers
4881 Make_Assignment_Statement (Loc,
4883 Make_Selected_Component (Loc,
4885 Unchecked_Convert_To (RTE (RE_Finalizable),
4886 New_Copy_Tree (Ctrl_Ref)),
4887 Selector_Name => Make_Identifier (Loc, Name_Prev)),
4888 Expression => New_Reference_To (Prev_Tmp, Loc)));
4891 Make_Assignment_Statement (Loc,
4893 Make_Selected_Component (Loc,
4895 Unchecked_Convert_To (RTE (RE_Finalizable),
4896 New_Copy_Tree (Ctrl_Ref)),
4897 Selector_Name => Make_Identifier (Loc, Name_Next)),
4898 Expression => New_Reference_To (Next_Tmp, Loc)));
4901 -- Adjust the target after the assignment when controlled (not in the
4902 -- init proc since it is an initialization more than an assignment).
4904 Append_List_To (Res,
4906 Ref => Duplicate_Subexpr_Move_Checks (L),
4908 Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc),
4909 With_Attach => Make_Integer_Literal (Loc, 0)));
4915 -- Could use comment here ???
4917 when RE_Not_Available =>
4919 end Make_Tag_Ctrl_Assignment;