1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2007, 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_Ch3; use Sem_Ch3;
50 with Sem_Ch8; use Sem_Ch8;
51 with Sem_Ch13; use Sem_Ch13;
52 with Sem_Eval; use Sem_Eval;
53 with Sem_Res; use Sem_Res;
54 with Sem_Util; use Sem_Util;
55 with Snames; use Snames;
56 with Stand; use Stand;
57 with Stringt; use Stringt;
58 with Targparm; use Targparm;
59 with Tbuild; use Tbuild;
60 with Ttypes; use Ttypes;
61 with Uintp; use Uintp;
62 with Validsw; use Validsw;
64 package body Exp_Ch5 is
66 function Change_Of_Representation (N : Node_Id) return Boolean;
67 -- Determine if the right hand side of the assignment N is a type
68 -- conversion which requires a change of representation. Called
69 -- only for the array and record cases.
71 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id);
72 -- N is an assignment which assigns an array value. This routine process
73 -- the various special cases and checks required for such assignments,
74 -- including change of representation. Rhs is normally simply the right
75 -- hand side of the assignment, except that if the right hand side is
76 -- a type conversion or a qualified expression, then the Rhs is the
77 -- actual expression inside any such type conversions or qualifications.
79 function Expand_Assign_Array_Loop
86 Rev : Boolean) return Node_Id;
87 -- N is an assignment statement which assigns an array value. This routine
88 -- expands the assignment into a loop (or nested loops for the case of a
89 -- multi-dimensional array) to do the assignment component by component.
90 -- Larray and Rarray are the entities of the actual arrays on the left
91 -- hand and right hand sides. L_Type and R_Type are the types of these
92 -- arrays (which may not be the same, due to either sliding, or to a
93 -- change of representation case). Ndim is the number of dimensions and
94 -- the parameter Rev indicates if the loops run normally (Rev = False),
95 -- or reversed (Rev = True). The value returned is the constructed
96 -- loop statement. Auxiliary declarations are inserted before node N
97 -- using the standard Insert_Actions mechanism.
99 procedure Expand_Assign_Record (N : Node_Id);
100 -- N is an assignment of a non-tagged record value. This routine handles
101 -- the case where the assignment must be made component by component,
102 -- either because the target is not byte aligned, or there is a change
103 -- of representation.
105 procedure Expand_Non_Function_Return (N : Node_Id);
106 -- Called by Expand_N_Simple_Return_Statement in case we're returning from
107 -- a procedure body, entry body, accept statement, or extended return
108 -- statement. Note that all non-function returns are simple return
111 procedure Expand_Simple_Function_Return (N : Node_Id);
112 -- Expand simple return from function. Called by
113 -- Expand_N_Simple_Return_Statement in case we're returning from a function
116 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
117 -- Generate the necessary code for controlled and tagged assignment,
118 -- that is to say, finalization of the target before, adjustement of
119 -- the target after and save and restore of the tag and finalization
120 -- pointers which are not 'part of the value' and must not be changed
121 -- upon assignment. N is the original Assignment node.
123 ------------------------------
124 -- Change_Of_Representation --
125 ------------------------------
127 function Change_Of_Representation (N : Node_Id) return Boolean is
128 Rhs : constant Node_Id := Expression (N);
131 Nkind (Rhs) = N_Type_Conversion
133 not Same_Representation (Etype (Rhs), Etype (Expression (Rhs)));
134 end Change_Of_Representation;
136 -------------------------
137 -- Expand_Assign_Array --
138 -------------------------
140 -- There are two issues here. First, do we let Gigi do a block move, or
141 -- do we expand out into a loop? Second, we need to set the two flags
142 -- Forwards_OK and Backwards_OK which show whether the block move (or
143 -- corresponding loops) can be legitimately done in a forwards (low to
144 -- high) or backwards (high to low) manner.
146 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is
147 Loc : constant Source_Ptr := Sloc (N);
149 Lhs : constant Node_Id := Name (N);
151 Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs);
152 Act_Rhs : Node_Id := Get_Referenced_Object (Rhs);
154 L_Type : constant Entity_Id :=
155 Underlying_Type (Get_Actual_Subtype (Act_Lhs));
156 R_Type : Entity_Id :=
157 Underlying_Type (Get_Actual_Subtype (Act_Rhs));
159 L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice;
160 R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice;
162 Crep : constant Boolean := Change_Of_Representation (N);
167 Ndim : constant Pos := Number_Dimensions (L_Type);
169 Loop_Required : Boolean := False;
170 -- This switch is set to True if the array move must be done using
171 -- an explicit front end generated loop.
173 procedure Apply_Dereference (Arg : Node_Id);
174 -- If the argument is an access to an array, and the assignment is
175 -- converted into a procedure call, apply explicit dereference.
177 function Has_Address_Clause (Exp : Node_Id) return Boolean;
178 -- Test if Exp is a reference to an array whose declaration has
179 -- an address clause, or it is a slice of such an array.
181 function Is_Formal_Array (Exp : Node_Id) return Boolean;
182 -- Test if Exp is a reference to an array which is either a formal
183 -- parameter or a slice of a formal parameter. These are the cases
184 -- where hidden aliasing can occur.
186 function Is_Non_Local_Array (Exp : Node_Id) return Boolean;
187 -- Determine if Exp is a reference to an array variable which is other
188 -- than an object defined in the current scope, or a slice of such
189 -- an object. Such objects can be aliased to parameters (unlike local
190 -- array references).
192 -----------------------
193 -- Apply_Dereference --
194 -----------------------
196 procedure Apply_Dereference (Arg : Node_Id) is
197 Typ : constant Entity_Id := Etype (Arg);
199 if Is_Access_Type (Typ) then
200 Rewrite (Arg, Make_Explicit_Dereference (Loc,
201 Prefix => Relocate_Node (Arg)));
202 Analyze_And_Resolve (Arg, Designated_Type (Typ));
204 end Apply_Dereference;
206 ------------------------
207 -- Has_Address_Clause --
208 ------------------------
210 function Has_Address_Clause (Exp : Node_Id) return Boolean is
213 (Is_Entity_Name (Exp) and then
214 Present (Address_Clause (Entity (Exp))))
216 (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp)));
217 end Has_Address_Clause;
219 ---------------------
220 -- Is_Formal_Array --
221 ---------------------
223 function Is_Formal_Array (Exp : Node_Id) return Boolean is
226 (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp)))
228 (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp)));
231 ------------------------
232 -- Is_Non_Local_Array --
233 ------------------------
235 function Is_Non_Local_Array (Exp : Node_Id) return Boolean is
237 return (Is_Entity_Name (Exp)
238 and then Scope (Entity (Exp)) /= Current_Scope)
239 or else (Nkind (Exp) = N_Slice
240 and then Is_Non_Local_Array (Prefix (Exp)));
241 end Is_Non_Local_Array;
243 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
245 Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs);
246 Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs);
248 Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs);
249 Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs);
251 -- Start of processing for Expand_Assign_Array
254 -- Deal with length check. Note that the length check is done with
255 -- respect to the right hand side as given, not a possible underlying
256 -- renamed object, since this would generate incorrect extra checks.
258 Apply_Length_Check (Rhs, L_Type);
260 -- We start by assuming that the move can be done in either direction,
261 -- i.e. that the two sides are completely disjoint.
263 Set_Forwards_OK (N, True);
264 Set_Backwards_OK (N, True);
266 -- Normally it is only the slice case that can lead to overlap, and
267 -- explicit checks for slices are made below. But there is one case
268 -- where the slice can be implicit and invisible to us: when we have a
269 -- one dimensional array, and either both operands are parameters, or
270 -- one is a parameter (which can be a slice passed by reference) and the
271 -- other is a non-local variable. In this case the parameter could be a
272 -- slice that overlaps with the other operand.
274 -- However, if the array subtype is a constrained first subtype in the
275 -- parameter case, then we don't have to worry about overlap, since
276 -- slice assignments aren't possible (other than for a slice denoting
279 -- Note: No overlap is possible if there is a change of representation,
280 -- so we can exclude this case.
285 ((Lhs_Formal and Rhs_Formal)
287 (Lhs_Formal and Rhs_Non_Local_Var)
289 (Rhs_Formal and Lhs_Non_Local_Var))
291 (not Is_Constrained (Etype (Lhs))
292 or else not Is_First_Subtype (Etype (Lhs)))
294 -- In the case of compiling for the Java or .NET Virtual Machine,
295 -- slices are always passed by making a copy, so we don't have to
296 -- worry about overlap. We also want to prevent generation of "<"
297 -- comparisons for array addresses, since that's a meaningless
298 -- operation on the VM.
300 and then VM_Target = No_VM
302 Set_Forwards_OK (N, False);
303 Set_Backwards_OK (N, False);
305 -- Note: the bit-packed case is not worrisome here, since if we have
306 -- a slice passed as a parameter, it is always aligned on a byte
307 -- boundary, and if there are no explicit slices, the assignment
308 -- can be performed directly.
311 -- We certainly must use a loop for change of representation and also
312 -- we use the operand of the conversion on the right hand side as the
313 -- effective right hand side (the component types must match in this
317 Act_Rhs := Get_Referenced_Object (Rhs);
318 R_Type := Get_Actual_Subtype (Act_Rhs);
319 Loop_Required := True;
321 -- We require a loop if the left side is possibly bit unaligned
323 elsif Possible_Bit_Aligned_Component (Lhs)
325 Possible_Bit_Aligned_Component (Rhs)
327 Loop_Required := True;
329 -- Arrays with controlled components are expanded into a loop to force
330 -- calls to Adjust at the component level.
332 elsif Has_Controlled_Component (L_Type) then
333 Loop_Required := True;
335 -- If object is atomic, we cannot tolerate a loop
337 elsif Is_Atomic_Object (Act_Lhs)
339 Is_Atomic_Object (Act_Rhs)
343 -- Loop is required if we have atomic components since we have to
344 -- be sure to do any accesses on an element by element basis.
346 elsif Has_Atomic_Components (L_Type)
347 or else Has_Atomic_Components (R_Type)
348 or else Is_Atomic (Component_Type (L_Type))
349 or else Is_Atomic (Component_Type (R_Type))
351 Loop_Required := True;
353 -- Case where no slice is involved
355 elsif not L_Slice and not R_Slice then
357 -- The following code deals with the case of unconstrained bit packed
358 -- arrays. The problem is that the template for such arrays contains
359 -- the bounds of the actual source level array, but the copy of an
360 -- entire array requires the bounds of the underlying array. It would
361 -- be nice if the back end could take care of this, but right now it
362 -- does not know how, so if we have such a type, then we expand out
363 -- into a loop, which is inefficient but works correctly. If we don't
364 -- do this, we get the wrong length computed for the array to be
365 -- moved. The two cases we need to worry about are:
367 -- Explicit deference of an unconstrained packed array type as in the
368 -- following example:
371 -- type BITS is array(INTEGER range <>) of BOOLEAN;
372 -- pragma PACK(BITS);
373 -- type A is access BITS;
376 -- P1 := new BITS (1 .. 65_535);
377 -- P2 := new BITS (1 .. 65_535);
381 -- A formal parameter reference with an unconstrained bit array type
382 -- is the other case we need to worry about (here we assume the same
383 -- BITS type declared above):
385 -- procedure Write_All (File : out BITS; Contents : BITS);
387 -- File.Storage := Contents;
390 -- We expand to a loop in either of these two cases.
392 -- Question for future thought. Another potentially more efficient
393 -- approach would be to create the actual subtype, and then do an
394 -- unchecked conversion to this actual subtype ???
396 Check_Unconstrained_Bit_Packed_Array : declare
398 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean;
399 -- Function to perform required test for the first case, above
400 -- (dereference of an unconstrained bit packed array).
402 -----------------------
403 -- Is_UBPA_Reference --
404 -----------------------
406 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is
407 Typ : constant Entity_Id := Underlying_Type (Etype (Opnd));
409 Des_Type : Entity_Id;
412 if Present (Packed_Array_Type (Typ))
413 and then Is_Array_Type (Packed_Array_Type (Typ))
414 and then not Is_Constrained (Packed_Array_Type (Typ))
418 elsif Nkind (Opnd) = N_Explicit_Dereference then
419 P_Type := Underlying_Type (Etype (Prefix (Opnd)));
421 if not Is_Access_Type (P_Type) then
425 Des_Type := Designated_Type (P_Type);
427 Is_Bit_Packed_Array (Des_Type)
428 and then not Is_Constrained (Des_Type);
434 end Is_UBPA_Reference;
436 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
439 if Is_UBPA_Reference (Lhs)
441 Is_UBPA_Reference (Rhs)
443 Loop_Required := True;
445 -- Here if we do not have the case of a reference to a bit packed
446 -- unconstrained array case. In this case gigi can most certainly
447 -- handle the assignment if a forwards move is allowed.
449 -- (could it handle the backwards case also???)
451 elsif Forwards_OK (N) then
454 end Check_Unconstrained_Bit_Packed_Array;
456 -- The back end can always handle the assignment if the right side is a
457 -- string literal (note that overlap is definitely impossible in this
458 -- case). If the type is packed, a string literal is always converted
459 -- into an aggregate, except in the case of a null slice, for which no
460 -- aggregate can be written. In that case, rewrite the assignment as a
461 -- null statement, a length check has already been emitted to verify
462 -- that the range of the left-hand side is empty.
464 -- Note that this code is not executed if we have an assignment of a
465 -- string literal to a non-bit aligned component of a record, a case
466 -- which cannot be handled by the backend.
468 elsif Nkind (Rhs) = N_String_Literal then
469 if String_Length (Strval (Rhs)) = 0
470 and then Is_Bit_Packed_Array (L_Type)
472 Rewrite (N, Make_Null_Statement (Loc));
478 -- If either operand is bit packed, then we need a loop, since we can't
479 -- be sure that the slice is byte aligned. Similarly, if either operand
480 -- is a possibly unaligned slice, then we need a loop (since the back
481 -- end cannot handle unaligned slices).
483 elsif Is_Bit_Packed_Array (L_Type)
484 or else Is_Bit_Packed_Array (R_Type)
485 or else Is_Possibly_Unaligned_Slice (Lhs)
486 or else Is_Possibly_Unaligned_Slice (Rhs)
488 Loop_Required := True;
490 -- If we are not bit-packed, and we have only one slice, then no overlap
491 -- is possible except in the parameter case, so we can let the back end
494 elsif not (L_Slice and R_Slice) then
495 if Forwards_OK (N) then
500 -- If the right-hand side is a string literal, introduce a temporary for
501 -- it, for use in the generated loop that will follow.
503 if Nkind (Rhs) = N_String_Literal then
505 Temp : constant Entity_Id :=
506 Make_Defining_Identifier (Loc, New_Internal_Name ('T'));
511 Make_Object_Declaration (Loc,
512 Defining_Identifier => Temp,
513 Object_Definition => New_Occurrence_Of (L_Type, Loc),
514 Expression => Relocate_Node (Rhs));
516 Insert_Action (N, Decl);
517 Rewrite (Rhs, New_Occurrence_Of (Temp, Loc));
518 R_Type := Etype (Temp);
522 -- Come here to complete the analysis
524 -- Loop_Required: Set to True if we know that a loop is required
525 -- regardless of overlap considerations.
527 -- Forwards_OK: Set to False if we already know that a forwards
528 -- move is not safe, else set to True.
530 -- Backwards_OK: Set to False if we already know that a backwards
531 -- move is not safe, else set to True
533 -- Our task at this stage is to complete the overlap analysis, which can
534 -- result in possibly setting Forwards_OK or Backwards_OK to False, and
535 -- then generating the final code, either by deciding that it is OK
536 -- after all to let Gigi handle it, or by generating appropriate code
540 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
541 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type));
543 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ);
544 Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ);
545 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ);
546 Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ);
548 Act_L_Array : Node_Id;
549 Act_R_Array : Node_Id;
555 Cresult : Compare_Result;
558 -- Get the expressions for the arrays. If we are dealing with a
559 -- private type, then convert to the underlying type. We can do
560 -- direct assignments to an array that is a private type, but we
561 -- cannot assign to elements of the array without this extra
562 -- unchecked conversion.
564 if Nkind (Act_Lhs) = N_Slice then
565 Larray := Prefix (Act_Lhs);
569 if Is_Private_Type (Etype (Larray)) then
572 (Underlying_Type (Etype (Larray)), Larray);
576 if Nkind (Act_Rhs) = N_Slice then
577 Rarray := Prefix (Act_Rhs);
581 if Is_Private_Type (Etype (Rarray)) then
584 (Underlying_Type (Etype (Rarray)), Rarray);
588 -- If both sides are slices, we must figure out whether it is safe
589 -- to do the move in one direction or the other. It is always safe
590 -- if there is a change of representation since obviously two arrays
591 -- with different representations cannot possibly overlap.
593 if (not Crep) and L_Slice and R_Slice then
594 Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
595 Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
597 -- If both left and right hand arrays are entity names, and refer
598 -- to different entities, then we know that the move is safe (the
599 -- two storage areas are completely disjoint).
601 if Is_Entity_Name (Act_L_Array)
602 and then Is_Entity_Name (Act_R_Array)
603 and then Entity (Act_L_Array) /= Entity (Act_R_Array)
607 -- Otherwise, we assume the worst, which is that the two arrays
608 -- are the same array. There is no need to check if we know that
609 -- is the case, because if we don't know it, we still have to
612 -- Generally if the same array is involved, then we have an
613 -- overlapping case. We will have to really assume the worst (i.e.
614 -- set neither of the OK flags) unless we can determine the lower
615 -- or upper bounds at compile time and compare them.
618 Cresult := Compile_Time_Compare (Left_Lo, Right_Lo);
620 if Cresult = Unknown then
621 Cresult := Compile_Time_Compare (Left_Hi, Right_Hi);
625 when LT | LE | EQ => Set_Backwards_OK (N, False);
626 when GT | GE => Set_Forwards_OK (N, False);
627 when NE | Unknown => Set_Backwards_OK (N, False);
628 Set_Forwards_OK (N, False);
633 -- If after that analysis, Forwards_OK is still True, and
634 -- Loop_Required is False, meaning that we have not discovered some
635 -- non-overlap reason for requiring a loop, then we can still let
638 if not Loop_Required then
639 if Forwards_OK (N) then
643 -- Here is where a memmove would be appropriate ???
647 -- At this stage we have to generate an explicit loop, and we have
648 -- the following cases:
650 -- Forwards_OK = True
652 -- Rnn : right_index := right_index'First;
653 -- for Lnn in left-index loop
654 -- left (Lnn) := right (Rnn);
655 -- Rnn := right_index'Succ (Rnn);
658 -- Note: the above code MUST be analyzed with checks off, because
659 -- otherwise the Succ could overflow. But in any case this is more
662 -- Forwards_OK = False, Backwards_OK = True
664 -- Rnn : right_index := right_index'Last;
665 -- for Lnn in reverse left-index loop
666 -- left (Lnn) := right (Rnn);
667 -- Rnn := right_index'Pred (Rnn);
670 -- Note: the above code MUST be analyzed with checks off, because
671 -- otherwise the Pred could overflow. But in any case this is more
674 -- Forwards_OK = Backwards_OK = False
676 -- This only happens if we have the same array on each side. It is
677 -- possible to create situations using overlays that violate this,
678 -- but we simply do not promise to get this "right" in this case.
680 -- There are two possible subcases. If the No_Implicit_Conditionals
681 -- restriction is set, then we generate the following code:
684 -- T : constant <operand-type> := rhs;
689 -- If implicit conditionals are permitted, then we generate:
691 -- if Left_Lo <= Right_Lo then
692 -- <code for Forwards_OK = True above>
694 -- <code for Backwards_OK = True above>
697 -- In order to detect possible aliasing, we examine the renamed
698 -- expression when the source or target is a renaming. However,
699 -- the renaming may be intended to capture an address that may be
700 -- affected by subsequent code, and therefore we must recover
701 -- the actual entity for the expansion that follows, not the
702 -- object it renames. In particular, if source or target designate
703 -- a portion of a dynamically allocated object, the pointer to it
704 -- may be reassigned but the renaming preserves the proper location.
706 if Is_Entity_Name (Rhs)
708 Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration
709 and then Nkind (Act_Rhs) = N_Slice
714 if Is_Entity_Name (Lhs)
716 Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration
717 and then Nkind (Act_Lhs) = N_Slice
722 -- Cases where either Forwards_OK or Backwards_OK is true
724 if Forwards_OK (N) or else Backwards_OK (N) then
725 if Controlled_Type (Component_Type (L_Type))
726 and then Base_Type (L_Type) = Base_Type (R_Type)
728 and then not No_Ctrl_Actions (N)
731 Proc : constant Entity_Id :=
732 TSS (Base_Type (L_Type), TSS_Slice_Assign);
736 Apply_Dereference (Larray);
737 Apply_Dereference (Rarray);
738 Actuals := New_List (
739 Duplicate_Subexpr (Larray, Name_Req => True),
740 Duplicate_Subexpr (Rarray, Name_Req => True),
741 Duplicate_Subexpr (Left_Lo, Name_Req => True),
742 Duplicate_Subexpr (Left_Hi, Name_Req => True),
743 Duplicate_Subexpr (Right_Lo, Name_Req => True),
744 Duplicate_Subexpr (Right_Hi, Name_Req => True));
748 Boolean_Literals (not Forwards_OK (N)), Loc));
751 Make_Procedure_Call_Statement (Loc,
752 Name => New_Reference_To (Proc, Loc),
753 Parameter_Associations => Actuals));
758 Expand_Assign_Array_Loop
759 (N, Larray, Rarray, L_Type, R_Type, Ndim,
760 Rev => not Forwards_OK (N)));
763 -- Case of both are false with No_Implicit_Conditionals
765 elsif Restriction_Active (No_Implicit_Conditionals) then
767 T : constant Entity_Id :=
768 Make_Defining_Identifier (Loc, Chars => Name_T);
772 Make_Block_Statement (Loc,
773 Declarations => New_List (
774 Make_Object_Declaration (Loc,
775 Defining_Identifier => T,
776 Constant_Present => True,
778 New_Occurrence_Of (Etype (Rhs), Loc),
779 Expression => Relocate_Node (Rhs))),
781 Handled_Statement_Sequence =>
782 Make_Handled_Sequence_Of_Statements (Loc,
783 Statements => New_List (
784 Make_Assignment_Statement (Loc,
785 Name => Relocate_Node (Lhs),
786 Expression => New_Occurrence_Of (T, Loc))))));
789 -- Case of both are false with implicit conditionals allowed
792 -- Before we generate this code, we must ensure that the left and
793 -- right side array types are defined. They may be itypes, and we
794 -- cannot let them be defined inside the if, since the first use
795 -- in the then may not be executed.
797 Ensure_Defined (L_Type, N);
798 Ensure_Defined (R_Type, N);
800 -- We normally compare addresses to find out which way round to
801 -- do the loop, since this is realiable, and handles the cases of
802 -- parameters, conversions etc. But we can't do that in the bit
803 -- packed case or the VM case, because addresses don't work there.
805 if not Is_Bit_Packed_Array (L_Type) and then VM_Target = No_VM then
809 Unchecked_Convert_To (RTE (RE_Integer_Address),
810 Make_Attribute_Reference (Loc,
812 Make_Indexed_Component (Loc,
814 Duplicate_Subexpr_Move_Checks (Larray, True),
815 Expressions => New_List (
816 Make_Attribute_Reference (Loc,
820 Attribute_Name => Name_First))),
821 Attribute_Name => Name_Address)),
824 Unchecked_Convert_To (RTE (RE_Integer_Address),
825 Make_Attribute_Reference (Loc,
827 Make_Indexed_Component (Loc,
829 Duplicate_Subexpr_Move_Checks (Rarray, True),
830 Expressions => New_List (
831 Make_Attribute_Reference (Loc,
835 Attribute_Name => Name_First))),
836 Attribute_Name => Name_Address)));
838 -- For the bit packed and VM cases we use the bounds. That's OK,
839 -- because we don't have to worry about parameters, since they
840 -- cannot cause overlap. Perhaps we should worry about weird slice
844 -- Copy the bounds and reset the Analyzed flag, because the
845 -- bounds of the index type itself may be universal, and must
846 -- must be reaanalyzed to acquire the proper type for Gigi.
848 Cleft_Lo := New_Copy_Tree (Left_Lo);
849 Cright_Lo := New_Copy_Tree (Right_Lo);
850 Set_Analyzed (Cleft_Lo, False);
851 Set_Analyzed (Cright_Lo, False);
855 Left_Opnd => Cleft_Lo,
856 Right_Opnd => Cright_Lo);
859 if Controlled_Type (Component_Type (L_Type))
860 and then Base_Type (L_Type) = Base_Type (R_Type)
862 and then not No_Ctrl_Actions (N)
865 -- Call TSS procedure for array assignment, passing the the
866 -- explicit bounds of right and left hand sides.
869 Proc : constant Node_Id :=
870 TSS (Base_Type (L_Type), TSS_Slice_Assign);
874 Apply_Dereference (Larray);
875 Apply_Dereference (Rarray);
876 Actuals := New_List (
877 Duplicate_Subexpr (Larray, Name_Req => True),
878 Duplicate_Subexpr (Rarray, Name_Req => True),
879 Duplicate_Subexpr (Left_Lo, Name_Req => True),
880 Duplicate_Subexpr (Left_Hi, Name_Req => True),
881 Duplicate_Subexpr (Right_Lo, Name_Req => True),
882 Duplicate_Subexpr (Right_Hi, Name_Req => True));
886 Right_Opnd => Condition));
889 Make_Procedure_Call_Statement (Loc,
890 Name => New_Reference_To (Proc, Loc),
891 Parameter_Associations => Actuals));
896 Make_Implicit_If_Statement (N,
897 Condition => Condition,
899 Then_Statements => New_List (
900 Expand_Assign_Array_Loop
901 (N, Larray, Rarray, L_Type, R_Type, Ndim,
904 Else_Statements => New_List (
905 Expand_Assign_Array_Loop
906 (N, Larray, Rarray, L_Type, R_Type, Ndim,
911 Analyze (N, Suppress => All_Checks);
915 when RE_Not_Available =>
917 end Expand_Assign_Array;
919 ------------------------------
920 -- Expand_Assign_Array_Loop --
921 ------------------------------
923 -- The following is an example of the loop generated for the case of a
924 -- two-dimensional array:
929 -- for L1b in 1 .. 100 loop
933 -- for L3b in 1 .. 100 loop
934 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
935 -- R4b := Tm1X2'succ(R4b);
938 -- R2b := Tm1X1'succ(R2b);
942 -- Here Rev is False, and Tm1Xn are the subscript types for the right hand
943 -- side. The declarations of R2b and R4b are inserted before the original
944 -- assignment statement.
946 function Expand_Assign_Array_Loop
953 Rev : Boolean) return Node_Id
955 Loc : constant Source_Ptr := Sloc (N);
957 Lnn : array (1 .. Ndim) of Entity_Id;
958 Rnn : array (1 .. Ndim) of Entity_Id;
959 -- Entities used as subscripts on left and right sides
961 L_Index_Type : array (1 .. Ndim) of Entity_Id;
962 R_Index_Type : array (1 .. Ndim) of Entity_Id;
963 -- Left and right index types
975 F_Or_L := Name_First;
979 -- Setup index types and subscript entities
986 L_Index := First_Index (L_Type);
987 R_Index := First_Index (R_Type);
989 for J in 1 .. Ndim loop
991 Make_Defining_Identifier (Loc,
992 Chars => New_Internal_Name ('L'));
995 Make_Defining_Identifier (Loc,
996 Chars => New_Internal_Name ('R'));
998 L_Index_Type (J) := Etype (L_Index);
999 R_Index_Type (J) := Etype (R_Index);
1001 Next_Index (L_Index);
1002 Next_Index (R_Index);
1006 -- Now construct the assignment statement
1009 ExprL : constant List_Id := New_List;
1010 ExprR : constant List_Id := New_List;
1013 for J in 1 .. Ndim loop
1014 Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc));
1015 Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc));
1019 Make_Assignment_Statement (Loc,
1021 Make_Indexed_Component (Loc,
1022 Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
1023 Expressions => ExprL),
1025 Make_Indexed_Component (Loc,
1026 Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
1027 Expressions => ExprR));
1029 -- We set assignment OK, since there are some cases, e.g. in object
1030 -- declarations, where we are actually assigning into a constant.
1031 -- If there really is an illegality, it was caught long before now,
1032 -- and was flagged when the original assignment was analyzed.
1034 Set_Assignment_OK (Name (Assign));
1036 -- Propagate the No_Ctrl_Actions flag to individual assignments
1038 Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
1041 -- Now construct the loop from the inside out, with the last subscript
1042 -- varying most rapidly. Note that Assign is first the raw assignment
1043 -- statement, and then subsequently the loop that wraps it up.
1045 for J in reverse 1 .. Ndim loop
1047 Make_Block_Statement (Loc,
1048 Declarations => New_List (
1049 Make_Object_Declaration (Loc,
1050 Defining_Identifier => Rnn (J),
1051 Object_Definition =>
1052 New_Occurrence_Of (R_Index_Type (J), Loc),
1054 Make_Attribute_Reference (Loc,
1055 Prefix => New_Occurrence_Of (R_Index_Type (J), Loc),
1056 Attribute_Name => F_Or_L))),
1058 Handled_Statement_Sequence =>
1059 Make_Handled_Sequence_Of_Statements (Loc,
1060 Statements => New_List (
1061 Make_Implicit_Loop_Statement (N,
1063 Make_Iteration_Scheme (Loc,
1064 Loop_Parameter_Specification =>
1065 Make_Loop_Parameter_Specification (Loc,
1066 Defining_Identifier => Lnn (J),
1067 Reverse_Present => Rev,
1068 Discrete_Subtype_Definition =>
1069 New_Reference_To (L_Index_Type (J), Loc))),
1071 Statements => New_List (
1074 Make_Assignment_Statement (Loc,
1075 Name => New_Occurrence_Of (Rnn (J), Loc),
1077 Make_Attribute_Reference (Loc,
1079 New_Occurrence_Of (R_Index_Type (J), Loc),
1080 Attribute_Name => S_Or_P,
1081 Expressions => New_List (
1082 New_Occurrence_Of (Rnn (J), Loc)))))))));
1086 end Expand_Assign_Array_Loop;
1088 --------------------------
1089 -- Expand_Assign_Record --
1090 --------------------------
1092 -- The only processing required is in the change of representation case,
1093 -- where we must expand the assignment to a series of field by field
1096 procedure Expand_Assign_Record (N : Node_Id) is
1097 Lhs : constant Node_Id := Name (N);
1098 Rhs : Node_Id := Expression (N);
1101 -- If change of representation, then extract the real right hand side
1102 -- from the type conversion, and proceed with component-wise assignment,
1103 -- since the two types are not the same as far as the back end is
1106 if Change_Of_Representation (N) then
1107 Rhs := Expression (Rhs);
1109 -- If this may be a case of a large bit aligned component, then proceed
1110 -- with component-wise assignment, to avoid possible clobbering of other
1111 -- components sharing bits in the first or last byte of the component to
1114 elsif Possible_Bit_Aligned_Component (Lhs)
1116 Possible_Bit_Aligned_Component (Rhs)
1120 -- If neither condition met, then nothing special to do, the back end
1121 -- can handle assignment of the entire component as a single entity.
1127 -- At this stage we know that we must do a component wise assignment
1130 Loc : constant Source_Ptr := Sloc (N);
1131 R_Typ : constant Entity_Id := Base_Type (Etype (Rhs));
1132 L_Typ : constant Entity_Id := Base_Type (Etype (Lhs));
1133 Decl : constant Node_Id := Declaration_Node (R_Typ);
1137 function Find_Component
1139 Comp : Entity_Id) return Entity_Id;
1140 -- Find the component with the given name in the underlying record
1141 -- declaration for Typ. We need to use the actual entity because the
1142 -- type may be private and resolution by identifier alone would fail.
1144 function Make_Component_List_Assign
1146 U_U : Boolean := False) return List_Id;
1147 -- Returns a sequence of statements to assign the components that
1148 -- are referenced in the given component list. The flag U_U is
1149 -- used to force the usage of the inferred value of the variant
1150 -- part expression as the switch for the generated case statement.
1152 function Make_Field_Assign
1154 U_U : Boolean := False) return Node_Id;
1155 -- Given C, the entity for a discriminant or component, build an
1156 -- assignment for the corresponding field values. The flag U_U
1157 -- signals the presence of an Unchecked_Union and forces the usage
1158 -- of the inferred discriminant value of C as the right hand side
1159 -- of the assignment.
1161 function Make_Field_Assigns (CI : List_Id) return List_Id;
1162 -- Given CI, a component items list, construct series of statements
1163 -- for fieldwise assignment of the corresponding components.
1165 --------------------
1166 -- Find_Component --
1167 --------------------
1169 function Find_Component
1171 Comp : Entity_Id) return Entity_Id
1173 Utyp : constant Entity_Id := Underlying_Type (Typ);
1177 C := First_Entity (Utyp);
1179 while Present (C) loop
1180 if Chars (C) = Chars (Comp) then
1186 raise Program_Error;
1189 --------------------------------
1190 -- Make_Component_List_Assign --
1191 --------------------------------
1193 function Make_Component_List_Assign
1195 U_U : Boolean := False) return List_Id
1197 CI : constant List_Id := Component_Items (CL);
1198 VP : constant Node_Id := Variant_Part (CL);
1208 Result := Make_Field_Assigns (CI);
1210 if Present (VP) then
1212 V := First_Non_Pragma (Variants (VP));
1214 while Present (V) loop
1217 DC := First (Discrete_Choices (V));
1218 while Present (DC) loop
1219 Append_To (DCH, New_Copy_Tree (DC));
1224 Make_Case_Statement_Alternative (Loc,
1225 Discrete_Choices => DCH,
1227 Make_Component_List_Assign (Component_List (V))));
1228 Next_Non_Pragma (V);
1231 -- If we have an Unchecked_Union, use the value of the inferred
1232 -- discriminant of the variant part expression as the switch
1233 -- for the case statement. The case statement may later be
1238 New_Copy (Get_Discriminant_Value (
1241 Discriminant_Constraint (Etype (Rhs))));
1244 Make_Selected_Component (Loc,
1245 Prefix => Duplicate_Subexpr (Rhs),
1247 Make_Identifier (Loc, Chars (Name (VP))));
1251 Make_Case_Statement (Loc,
1253 Alternatives => Alts));
1257 end Make_Component_List_Assign;
1259 -----------------------
1260 -- Make_Field_Assign --
1261 -----------------------
1263 function Make_Field_Assign
1265 U_U : Boolean := False) return Node_Id
1271 -- In the case of an Unchecked_Union, use the discriminant
1272 -- constraint value as on the right hand side of the assignment.
1276 New_Copy (Get_Discriminant_Value (C,
1278 Discriminant_Constraint (Etype (Rhs))));
1281 Make_Selected_Component (Loc,
1282 Prefix => Duplicate_Subexpr (Rhs),
1283 Selector_Name => New_Occurrence_Of (C, Loc));
1287 Make_Assignment_Statement (Loc,
1289 Make_Selected_Component (Loc,
1290 Prefix => Duplicate_Subexpr (Lhs),
1292 New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
1293 Expression => Expr);
1295 -- Set Assignment_OK, so discriminants can be assigned
1297 Set_Assignment_OK (Name (A), True);
1299 end Make_Field_Assign;
1301 ------------------------
1302 -- Make_Field_Assigns --
1303 ------------------------
1305 function Make_Field_Assigns (CI : List_Id) return List_Id is
1312 while Present (Item) loop
1313 if Nkind (Item) = N_Component_Declaration then
1315 (Result, Make_Field_Assign (Defining_Identifier (Item)));
1322 end Make_Field_Assigns;
1324 -- Start of processing for Expand_Assign_Record
1327 -- Note that we use the base types for this processing. This results
1328 -- in some extra work in the constrained case, but the change of
1329 -- representation case is so unusual that it is not worth the effort.
1331 -- First copy the discriminants. This is done unconditionally. It
1332 -- is required in the unconstrained left side case, and also in the
1333 -- case where this assignment was constructed during the expansion
1334 -- of a type conversion (since initialization of discriminants is
1335 -- suppressed in this case). It is unnecessary but harmless in
1338 if Has_Discriminants (L_Typ) then
1339 F := First_Discriminant (R_Typ);
1340 while Present (F) loop
1342 if Is_Unchecked_Union (Base_Type (R_Typ)) then
1343 Insert_Action (N, Make_Field_Assign (F, True));
1345 Insert_Action (N, Make_Field_Assign (F));
1348 Next_Discriminant (F);
1352 -- We know the underlying type is a record, but its current view
1353 -- may be private. We must retrieve the usable record declaration.
1355 if Nkind (Decl) = N_Private_Type_Declaration
1356 and then Present (Full_View (R_Typ))
1358 RDef := Type_Definition (Declaration_Node (Full_View (R_Typ)));
1360 RDef := Type_Definition (Decl);
1363 if Nkind (RDef) = N_Record_Definition
1364 and then Present (Component_List (RDef))
1367 if Is_Unchecked_Union (R_Typ) then
1369 Make_Component_List_Assign (Component_List (RDef), True));
1372 (N, Make_Component_List_Assign (Component_List (RDef)));
1375 Rewrite (N, Make_Null_Statement (Loc));
1379 end Expand_Assign_Record;
1381 -----------------------------------
1382 -- Expand_N_Assignment_Statement --
1383 -----------------------------------
1385 -- This procedure implements various cases where an assignment statement
1386 -- cannot just be passed on to the back end in untransformed state.
1388 procedure Expand_N_Assignment_Statement (N : Node_Id) is
1389 Loc : constant Source_Ptr := Sloc (N);
1390 Lhs : constant Node_Id := Name (N);
1391 Rhs : constant Node_Id := Expression (N);
1392 Typ : constant Entity_Id := Underlying_Type (Etype (Lhs));
1396 -- Ada 2005 (AI-327): Handle assignment to priority of protected object
1398 -- Rewrite an assignment to X'Priority into a run-time call
1400 -- For example: X'Priority := New_Prio_Expr;
1401 -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr);
1403 -- Note that although X'Priority is notionally an object, it is quite
1404 -- deliberately not defined as an aliased object in the RM. This means
1405 -- that it works fine to rewrite it as a call, without having to worry
1406 -- about complications that would other arise from X'Priority'Access,
1407 -- which is illegal, because of the lack of aliasing.
1409 if Ada_Version >= Ada_05 then
1412 Conctyp : Entity_Id;
1415 RT_Subprg_Name : Node_Id;
1418 -- Handle chains of renamings
1421 while Nkind (Ent) in N_Has_Entity
1422 and then Present (Entity (Ent))
1423 and then Present (Renamed_Object (Entity (Ent)))
1425 Ent := Renamed_Object (Entity (Ent));
1428 -- The attribute Priority applied to protected objects has been
1429 -- previously expanded into a call to the Get_Ceiling run-time
1432 if Nkind (Ent) = N_Function_Call
1433 and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling)
1435 Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling))
1437 -- Look for the enclosing concurrent type
1439 Conctyp := Current_Scope;
1440 while not Is_Concurrent_Type (Conctyp) loop
1441 Conctyp := Scope (Conctyp);
1444 pragma Assert (Is_Protected_Type (Conctyp));
1446 -- Generate the first actual of the call
1448 Subprg := Current_Scope;
1449 while not Present (Protected_Body_Subprogram (Subprg)) loop
1450 Subprg := Scope (Subprg);
1453 -- Select the appropriate run-time call
1455 if Number_Entries (Conctyp) = 0 then
1457 New_Reference_To (RTE (RE_Set_Ceiling), Loc);
1460 New_Reference_To (RTE (RO_PE_Set_Ceiling), Loc);
1464 Make_Procedure_Call_Statement (Loc,
1465 Name => RT_Subprg_Name,
1466 Parameter_Associations => New_List (
1467 New_Copy_Tree (First (Parameter_Associations (Ent))),
1468 Relocate_Node (Expression (N))));
1477 -- First deal with generation of range check if required. For now we do
1478 -- this only for discrete types.
1480 if Do_Range_Check (Rhs)
1481 and then Is_Discrete_Type (Typ)
1483 Set_Do_Range_Check (Rhs, False);
1484 Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed);
1487 -- Check for a special case where a high level transformation is
1488 -- required. If we have either of:
1493 -- where P is a reference to a bit packed array, then we have to unwind
1494 -- the assignment. The exact meaning of being a reference to a bit
1495 -- packed array is as follows:
1497 -- An indexed component whose prefix is a bit packed array is a
1498 -- reference to a bit packed array.
1500 -- An indexed component or selected component whose prefix is a
1501 -- reference to a bit packed array is itself a reference ot a
1502 -- bit packed array.
1504 -- The required transformation is
1506 -- Tnn : prefix_type := P;
1507 -- Tnn.field := rhs;
1512 -- Tnn : prefix_type := P;
1513 -- Tnn (subscr) := rhs;
1516 -- Since P is going to be evaluated more than once, any subscripts
1517 -- in P must have their evaluation forced.
1519 if (Nkind (Lhs) = N_Indexed_Component
1521 Nkind (Lhs) = N_Selected_Component)
1522 and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs))
1525 BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs));
1526 BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr);
1527 Tnn : constant Entity_Id :=
1528 Make_Defining_Identifier (Loc,
1529 Chars => New_Internal_Name ('T'));
1532 -- Insert the post assignment first, because we want to copy the
1533 -- BPAR_Expr tree before it gets analyzed in the context of the
1534 -- pre assignment. Note that we do not analyze the post assignment
1535 -- yet (we cannot till we have completed the analysis of the pre
1536 -- assignment). As usual, the analysis of this post assignment
1537 -- will happen on its own when we "run into" it after finishing
1538 -- the current assignment.
1541 Make_Assignment_Statement (Loc,
1542 Name => New_Copy_Tree (BPAR_Expr),
1543 Expression => New_Occurrence_Of (Tnn, Loc)));
1545 -- At this stage BPAR_Expr is a reference to a bit packed array
1546 -- where the reference was not expanded in the original tree,
1547 -- since it was on the left side of an assignment. But in the
1548 -- pre-assignment statement (the object definition), BPAR_Expr
1549 -- will end up on the right hand side, and must be reexpanded. To
1550 -- achieve this, we reset the analyzed flag of all selected and
1551 -- indexed components down to the actual indexed component for
1552 -- the packed array.
1556 Set_Analyzed (Exp, False);
1558 if Nkind (Exp) = N_Selected_Component
1560 Nkind (Exp) = N_Indexed_Component
1562 Exp := Prefix (Exp);
1568 -- Now we can insert and analyze the pre-assignment
1570 -- If the right-hand side requires a transient scope, it has
1571 -- already been placed on the stack. However, the declaration is
1572 -- inserted in the tree outside of this scope, and must reflect
1573 -- the proper scope for its variable. This awkward bit is forced
1574 -- by the stricter scope discipline imposed by GCC 2.97.
1577 Uses_Transient_Scope : constant Boolean :=
1579 and then N = Node_To_Be_Wrapped;
1582 if Uses_Transient_Scope then
1583 Push_Scope (Scope (Current_Scope));
1586 Insert_Before_And_Analyze (N,
1587 Make_Object_Declaration (Loc,
1588 Defining_Identifier => Tnn,
1589 Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc),
1590 Expression => BPAR_Expr));
1592 if Uses_Transient_Scope then
1597 -- Now fix up the original assignment and continue processing
1599 Rewrite (Prefix (Lhs),
1600 New_Occurrence_Of (Tnn, Loc));
1602 -- We do not need to reanalyze that assignment, and we do not need
1603 -- to worry about references to the temporary, but we do need to
1604 -- make sure that the temporary is not marked as a true constant
1605 -- since we now have a generated assignment to it!
1607 Set_Is_True_Constant (Tnn, False);
1611 -- When we have the appropriate type of aggregate in the expression (it
1612 -- has been determined during analysis of the aggregate by setting the
1613 -- delay flag), let's perform in place assignment and thus avoid
1614 -- creating a temporary.
1616 if Is_Delayed_Aggregate (Rhs) then
1617 Convert_Aggr_In_Assignment (N);
1618 Rewrite (N, Make_Null_Statement (Loc));
1623 -- Apply discriminant check if required. If Lhs is an access type to a
1624 -- designated type with discriminants, we must always check.
1626 if Has_Discriminants (Etype (Lhs)) then
1628 -- Skip discriminant check if change of representation. Will be
1629 -- done when the change of representation is expanded out.
1631 if not Change_Of_Representation (N) then
1632 Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs);
1635 -- If the type is private without discriminants, and the full type
1636 -- has discriminants (necessarily with defaults) a check may still be
1637 -- necessary if the Lhs is aliased. The private determinants must be
1638 -- visible to build the discriminant constraints.
1640 -- Only an explicit dereference that comes from source indicates
1641 -- aliasing. Access to formals of protected operations and entries
1642 -- create dereferences but are not semantic aliasings.
1644 elsif Is_Private_Type (Etype (Lhs))
1645 and then Has_Discriminants (Typ)
1646 and then Nkind (Lhs) = N_Explicit_Dereference
1647 and then Comes_From_Source (Lhs)
1650 Lt : constant Entity_Id := Etype (Lhs);
1652 Set_Etype (Lhs, Typ);
1653 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1654 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1655 Set_Etype (Lhs, Lt);
1658 -- If the Lhs has a private type with unknown discriminants, it
1659 -- may have a full view with discriminants, but those are nameable
1660 -- only in the underlying type, so convert the Rhs to it before
1661 -- potential checking.
1663 elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs)))
1664 and then Has_Discriminants (Typ)
1666 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1667 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1669 -- In the access type case, we need the same discriminant check, and
1670 -- also range checks if we have an access to constrained array.
1672 elsif Is_Access_Type (Etype (Lhs))
1673 and then Is_Constrained (Designated_Type (Etype (Lhs)))
1675 if Has_Discriminants (Designated_Type (Etype (Lhs))) then
1677 -- Skip discriminant check if change of representation. Will be
1678 -- done when the change of representation is expanded out.
1680 if not Change_Of_Representation (N) then
1681 Apply_Discriminant_Check (Rhs, Etype (Lhs));
1684 elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then
1685 Apply_Range_Check (Rhs, Etype (Lhs));
1687 if Is_Constrained (Etype (Lhs)) then
1688 Apply_Length_Check (Rhs, Etype (Lhs));
1691 if Nkind (Rhs) = N_Allocator then
1693 Target_Typ : constant Entity_Id := Etype (Expression (Rhs));
1694 C_Es : Check_Result;
1701 Etype (Designated_Type (Etype (Lhs))));
1713 -- Apply range check for access type case
1715 elsif Is_Access_Type (Etype (Lhs))
1716 and then Nkind (Rhs) = N_Allocator
1717 and then Nkind (Expression (Rhs)) = N_Qualified_Expression
1719 Analyze_And_Resolve (Expression (Rhs));
1721 (Expression (Rhs), Designated_Type (Etype (Lhs)));
1724 -- Ada 2005 (AI-231): Generate the run-time check
1726 if Is_Access_Type (Typ)
1727 and then Can_Never_Be_Null (Etype (Lhs))
1728 and then not Can_Never_Be_Null (Etype (Rhs))
1730 Apply_Constraint_Check (Rhs, Etype (Lhs));
1733 -- Case of assignment to a bit packed array element
1735 if Nkind (Lhs) = N_Indexed_Component
1736 and then Is_Bit_Packed_Array (Etype (Prefix (Lhs)))
1738 Expand_Bit_Packed_Element_Set (N);
1741 -- Build-in-place function call case. Note that we're not yet doing
1742 -- build-in-place for user-written assignment statements (the assignment
1743 -- here came from an aggregate.)
1745 elsif Ada_Version >= Ada_05
1746 and then Is_Build_In_Place_Function_Call (Rhs)
1748 Make_Build_In_Place_Call_In_Assignment (N, Rhs);
1750 elsif Is_Tagged_Type (Typ) and then Is_Value_Type (Etype (Lhs)) then
1752 -- Nothing to do for valuetypes
1753 -- ??? Set_Scope_Is_Transient (False);
1757 elsif Is_Tagged_Type (Typ)
1758 or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ))
1760 Tagged_Case : declare
1761 L : List_Id := No_List;
1762 Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N);
1765 -- In the controlled case, we need to make sure that function
1766 -- calls are evaluated before finalizing the target. In all cases,
1767 -- it makes the expansion easier if the side-effects are removed
1770 Remove_Side_Effects (Lhs);
1771 Remove_Side_Effects (Rhs);
1773 -- Avoid recursion in the mechanism
1777 -- If dispatching assignment, we need to dispatch to _assign
1779 if Is_Class_Wide_Type (Typ)
1781 -- If the type is tagged, we may as well use the predefined
1782 -- primitive assignment. This avoids inlining a lot of code
1783 -- and in the class-wide case, the assignment is replaced by
1784 -- dispatch call to _assign. Note that this cannot be done when
1785 -- discriminant checks are locally suppressed (as in extension
1786 -- aggregate expansions) because otherwise the discriminant
1787 -- check will be performed within the _assign call. It is also
1788 -- suppressed for assignmments created by the expander that
1789 -- correspond to initializations, where we do want to copy the
1790 -- tag (No_Ctrl_Actions flag set True). by the expander and we
1791 -- do not need to mess with tags ever (Expand_Ctrl_Actions flag
1792 -- is set True in this case).
1794 or else (Is_Tagged_Type (Typ)
1795 and then not Is_Value_Type (Etype (Lhs))
1796 and then Chars (Current_Scope) /= Name_uAssign
1797 and then Expand_Ctrl_Actions
1798 and then not Discriminant_Checks_Suppressed (Empty))
1800 -- Fetch the primitive op _assign and proper type to call it.
1801 -- Because of possible conflits between private and full view
1802 -- the proper type is fetched directly from the operation
1806 Op : constant Entity_Id :=
1807 Find_Prim_Op (Typ, Name_uAssign);
1808 F_Typ : Entity_Id := Etype (First_Formal (Op));
1811 -- If the assignment is dispatching, make sure to use the
1814 if Is_Class_Wide_Type (Typ) then
1815 F_Typ := Class_Wide_Type (F_Typ);
1820 -- In case of assignment to a class-wide tagged type, before
1821 -- the assignment we generate run-time check to ensure that
1822 -- the tags of source and target match.
1824 if Is_Class_Wide_Type (Typ)
1825 and then Is_Tagged_Type (Typ)
1826 and then Is_Tagged_Type (Underlying_Type (Etype (Rhs)))
1829 Make_Raise_Constraint_Error (Loc,
1833 Make_Selected_Component (Loc,
1834 Prefix => Duplicate_Subexpr (Lhs),
1836 Make_Identifier (Loc,
1837 Chars => Name_uTag)),
1839 Make_Selected_Component (Loc,
1840 Prefix => Duplicate_Subexpr (Rhs),
1842 Make_Identifier (Loc,
1843 Chars => Name_uTag))),
1844 Reason => CE_Tag_Check_Failed));
1848 Make_Procedure_Call_Statement (Loc,
1849 Name => New_Reference_To (Op, Loc),
1850 Parameter_Associations => New_List (
1851 Unchecked_Convert_To (F_Typ,
1852 Duplicate_Subexpr (Lhs)),
1853 Unchecked_Convert_To (F_Typ,
1854 Duplicate_Subexpr (Rhs)))));
1858 L := Make_Tag_Ctrl_Assignment (N);
1860 -- We can't afford to have destructive Finalization Actions in
1861 -- the Self assignment case, so if the target and the source
1862 -- are not obviously different, code is generated to avoid the
1863 -- self assignment case:
1865 -- if lhs'address /= rhs'address then
1866 -- <code for controlled and/or tagged assignment>
1869 if not Statically_Different (Lhs, Rhs)
1870 and then Expand_Ctrl_Actions
1873 Make_Implicit_If_Statement (N,
1877 Make_Attribute_Reference (Loc,
1878 Prefix => Duplicate_Subexpr (Lhs),
1879 Attribute_Name => Name_Address),
1882 Make_Attribute_Reference (Loc,
1883 Prefix => Duplicate_Subexpr (Rhs),
1884 Attribute_Name => Name_Address)),
1886 Then_Statements => L));
1889 -- We need to set up an exception handler for implementing
1890 -- 7.6.1(18). The remaining adjustments are tackled by the
1891 -- implementation of adjust for record_controllers (see
1894 -- This is skipped if we have no finalization
1896 if Expand_Ctrl_Actions
1897 and then not Restriction_Active (No_Finalization)
1900 Make_Block_Statement (Loc,
1901 Handled_Statement_Sequence =>
1902 Make_Handled_Sequence_Of_Statements (Loc,
1904 Exception_Handlers => New_List (
1905 Make_Handler_For_Ctrl_Operation (Loc)))));
1910 Make_Block_Statement (Loc,
1911 Handled_Statement_Sequence =>
1912 Make_Handled_Sequence_Of_Statements (Loc, Statements => L)));
1914 -- If no restrictions on aborts, protect the whole assignement
1915 -- for controlled objects as per 9.8(11).
1917 if Controlled_Type (Typ)
1918 and then Expand_Ctrl_Actions
1919 and then Abort_Allowed
1922 Blk : constant Entity_Id :=
1924 (E_Block, Current_Scope, Sloc (N), 'B');
1927 Set_Scope (Blk, Current_Scope);
1928 Set_Etype (Blk, Standard_Void_Type);
1929 Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N)));
1931 Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer));
1932 Set_At_End_Proc (Handled_Statement_Sequence (N),
1933 New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc));
1934 Expand_At_End_Handler
1935 (Handled_Statement_Sequence (N), Blk);
1939 -- N has been rewritten to a block statement for which it is
1940 -- known by construction that no checks are necessary: analyze
1941 -- it with all checks suppressed.
1943 Analyze (N, Suppress => All_Checks);
1949 elsif Is_Array_Type (Typ) then
1951 Actual_Rhs : Node_Id := Rhs;
1954 while Nkind (Actual_Rhs) = N_Type_Conversion
1956 Nkind (Actual_Rhs) = N_Qualified_Expression
1958 Actual_Rhs := Expression (Actual_Rhs);
1961 Expand_Assign_Array (N, Actual_Rhs);
1967 elsif Is_Record_Type (Typ) then
1968 Expand_Assign_Record (N);
1971 -- Scalar types. This is where we perform the processing related to the
1972 -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid
1975 elsif Is_Scalar_Type (Typ) then
1977 -- Case where right side is known valid
1979 if Expr_Known_Valid (Rhs) then
1981 -- Here the right side is valid, so it is fine. The case to deal
1982 -- with is when the left side is a local variable reference whose
1983 -- value is not currently known to be valid. If this is the case,
1984 -- and the assignment appears in an unconditional context, then we
1985 -- can mark the left side as now being valid.
1987 if Is_Local_Variable_Reference (Lhs)
1988 and then not Is_Known_Valid (Entity (Lhs))
1989 and then In_Unconditional_Context (N)
1991 Set_Is_Known_Valid (Entity (Lhs), True);
1994 -- Case where right side may be invalid in the sense of the RM
1995 -- reference above. The RM does not require that we check for the
1996 -- validity on an assignment, but it does require that the assignment
1997 -- of an invalid value not cause erroneous behavior.
1999 -- The general approach in GNAT is to use the Is_Known_Valid flag
2000 -- to avoid the need for validity checking on assignments. However
2001 -- in some cases, we have to do validity checking in order to make
2002 -- sure that the setting of this flag is correct.
2005 -- Validate right side if we are validating copies
2007 if Validity_Checks_On
2008 and then Validity_Check_Copies
2010 -- Skip this if left hand side is an array or record component
2011 -- and elementary component validity checks are suppressed.
2013 if (Nkind (Lhs) = N_Selected_Component
2015 Nkind (Lhs) = N_Indexed_Component)
2016 and then not Validity_Check_Components
2023 -- We can propagate this to the left side where appropriate
2025 if Is_Local_Variable_Reference (Lhs)
2026 and then not Is_Known_Valid (Entity (Lhs))
2027 and then In_Unconditional_Context (N)
2029 Set_Is_Known_Valid (Entity (Lhs), True);
2032 -- Otherwise check to see what should be done
2034 -- If left side is a local variable, then we just set its flag to
2035 -- indicate that its value may no longer be valid, since we are
2036 -- copying a potentially invalid value.
2038 elsif Is_Local_Variable_Reference (Lhs) then
2039 Set_Is_Known_Valid (Entity (Lhs), False);
2041 -- Check for case of a nonlocal variable on the left side which
2042 -- is currently known to be valid. In this case, we simply ensure
2043 -- that the right side is valid. We only play the game of copying
2044 -- validity status for local variables, since we are doing this
2045 -- statically, not by tracing the full flow graph.
2047 elsif Is_Entity_Name (Lhs)
2048 and then Is_Known_Valid (Entity (Lhs))
2050 -- Note: If Validity_Checking mode is set to none, we ignore
2051 -- the Ensure_Valid call so don't worry about that case here.
2055 -- In all other cases, we can safely copy an invalid value without
2056 -- worrying about the status of the left side. Since it is not a
2057 -- variable reference it will not be considered
2058 -- as being known to be valid in any case.
2066 -- Defend against invalid subscripts on left side if we are in standard
2067 -- validity checking mode. No need to do this if we are checking all
2070 if Validity_Checks_On
2071 and then Validity_Check_Default
2072 and then not Validity_Check_Subscripts
2074 Check_Valid_Lvalue_Subscripts (Lhs);
2078 when RE_Not_Available =>
2080 end Expand_N_Assignment_Statement;
2082 ------------------------------
2083 -- Expand_N_Block_Statement --
2084 ------------------------------
2086 -- Encode entity names defined in block statement
2088 procedure Expand_N_Block_Statement (N : Node_Id) is
2090 Qualify_Entity_Names (N);
2091 end Expand_N_Block_Statement;
2093 -----------------------------
2094 -- Expand_N_Case_Statement --
2095 -----------------------------
2097 procedure Expand_N_Case_Statement (N : Node_Id) is
2098 Loc : constant Source_Ptr := Sloc (N);
2099 Expr : constant Node_Id := Expression (N);
2107 -- Check for the situation where we know at compile time which branch
2110 if Compile_Time_Known_Value (Expr) then
2111 Alt := Find_Static_Alternative (N);
2113 -- Move statements from this alternative after the case statement.
2114 -- They are already analyzed, so will be skipped by the analyzer.
2116 Insert_List_After (N, Statements (Alt));
2118 -- That leaves the case statement as a shell. So now we can kill all
2119 -- other alternatives in the case statement.
2121 Kill_Dead_Code (Expression (N));
2127 -- Loop through case alternatives, skipping pragmas, and skipping
2128 -- the one alternative that we select (and therefore retain).
2130 A := First (Alternatives (N));
2131 while Present (A) loop
2133 and then Nkind (A) = N_Case_Statement_Alternative
2135 Kill_Dead_Code (Statements (A), Warn_On_Deleted_Code);
2142 Rewrite (N, Make_Null_Statement (Loc));
2146 -- Here if the choice is not determined at compile time
2149 Last_Alt : constant Node_Id := Last (Alternatives (N));
2151 Others_Present : Boolean;
2152 Others_Node : Node_Id;
2154 Then_Stms : List_Id;
2155 Else_Stms : List_Id;
2158 if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then
2159 Others_Present := True;
2160 Others_Node := Last_Alt;
2162 Others_Present := False;
2165 -- First step is to worry about possible invalid argument. The RM
2166 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
2167 -- outside the base range), then Constraint_Error must be raised.
2169 -- Case of validity check required (validity checks are on, the
2170 -- expression is not known to be valid, and the case statement
2171 -- comes from source -- no need to validity check internally
2172 -- generated case statements).
2174 if Validity_Check_Default then
2175 Ensure_Valid (Expr);
2178 -- If there is only a single alternative, just replace it with the
2179 -- sequence of statements since obviously that is what is going to
2180 -- be executed in all cases.
2182 Len := List_Length (Alternatives (N));
2185 -- We still need to evaluate the expression if it has any
2188 Remove_Side_Effects (Expression (N));
2190 Insert_List_After (N, Statements (First (Alternatives (N))));
2192 -- That leaves the case statement as a shell. The alternative that
2193 -- will be executed is reset to a null list. So now we can kill
2194 -- the entire case statement.
2196 Kill_Dead_Code (Expression (N));
2197 Rewrite (N, Make_Null_Statement (Loc));
2201 -- An optimization. If there are only two alternatives, and only
2202 -- a single choice, then rewrite the whole case statement as an
2203 -- if statement, since this can result in susbequent optimizations.
2204 -- This helps not only with case statements in the source of a
2205 -- simple form, but also with generated code (discriminant check
2206 -- functions in particular)
2209 Chlist := Discrete_Choices (First (Alternatives (N)));
2211 if List_Length (Chlist) = 1 then
2212 Choice := First (Chlist);
2214 Then_Stms := Statements (First (Alternatives (N)));
2215 Else_Stms := Statements (Last (Alternatives (N)));
2217 -- For TRUE, generate "expression", not expression = true
2219 if Nkind (Choice) = N_Identifier
2220 and then Entity (Choice) = Standard_True
2222 Cond := Expression (N);
2224 -- For FALSE, generate "expression" and switch then/else
2226 elsif Nkind (Choice) = N_Identifier
2227 and then Entity (Choice) = Standard_False
2229 Cond := Expression (N);
2230 Else_Stms := Statements (First (Alternatives (N)));
2231 Then_Stms := Statements (Last (Alternatives (N)));
2233 -- For a range, generate "expression in range"
2235 elsif Nkind (Choice) = N_Range
2236 or else (Nkind (Choice) = N_Attribute_Reference
2237 and then Attribute_Name (Choice) = Name_Range)
2238 or else (Is_Entity_Name (Choice)
2239 and then Is_Type (Entity (Choice)))
2240 or else Nkind (Choice) = N_Subtype_Indication
2244 Left_Opnd => Expression (N),
2245 Right_Opnd => Relocate_Node (Choice));
2247 -- For any other subexpression "expression = value"
2252 Left_Opnd => Expression (N),
2253 Right_Opnd => Relocate_Node (Choice));
2256 -- Now rewrite the case as an IF
2259 Make_If_Statement (Loc,
2261 Then_Statements => Then_Stms,
2262 Else_Statements => Else_Stms));
2268 -- If the last alternative is not an Others choice, replace it with
2269 -- an N_Others_Choice. Note that we do not bother to call Analyze on
2270 -- the modified case statement, since it's only effect would be to
2271 -- compute the contents of the Others_Discrete_Choices which is not
2272 -- needed by the back end anyway.
2274 -- The reason we do this is that the back end always needs some
2275 -- default for a switch, so if we have not supplied one in the
2276 -- processing above for validity checking, then we need to supply
2279 if not Others_Present then
2280 Others_Node := Make_Others_Choice (Sloc (Last_Alt));
2281 Set_Others_Discrete_Choices
2282 (Others_Node, Discrete_Choices (Last_Alt));
2283 Set_Discrete_Choices (Last_Alt, New_List (Others_Node));
2286 end Expand_N_Case_Statement;
2288 -----------------------------
2289 -- Expand_N_Exit_Statement --
2290 -----------------------------
2292 -- The only processing required is to deal with a possible C/Fortran
2293 -- boolean value used as the condition for the exit statement.
2295 procedure Expand_N_Exit_Statement (N : Node_Id) is
2297 Adjust_Condition (Condition (N));
2298 end Expand_N_Exit_Statement;
2300 ----------------------------------------
2301 -- Expand_N_Extended_Return_Statement --
2302 ----------------------------------------
2304 -- If there is a Handled_Statement_Sequence, we rewrite this:
2306 -- return Result : T := <expression> do
2307 -- <handled_seq_of_stms>
2313 -- Result : T := <expression>;
2315 -- <handled_seq_of_stms>
2319 -- Otherwise (no Handled_Statement_Sequence), we rewrite this:
2321 -- return Result : T := <expression>;
2325 -- return <expression>;
2327 -- unless it's build-in-place or there's no <expression>, in which case
2331 -- Result : T := <expression>;
2336 -- Note that this case could have been written by the user as an extended
2337 -- return statement, or could have been transformed to this from a simple
2338 -- return statement.
2340 -- That is, we need to have a reified return object if there are statements
2341 -- (which might refer to it) or if we're doing build-in-place (so we can
2342 -- set its address to the final resting place or if there is no expression
2343 -- (in which case default initial values might need to be set).
2345 procedure Expand_N_Extended_Return_Statement (N : Node_Id) is
2346 Loc : constant Source_Ptr := Sloc (N);
2348 Return_Object_Entity : constant Entity_Id :=
2349 First_Entity (Return_Statement_Entity (N));
2350 Return_Object_Decl : constant Node_Id :=
2351 Parent (Return_Object_Entity);
2352 Parent_Function : constant Entity_Id :=
2353 Return_Applies_To (Return_Statement_Entity (N));
2354 Is_Build_In_Place : constant Boolean :=
2355 Is_Build_In_Place_Function (Parent_Function);
2357 Return_Stm : Node_Id;
2358 Statements : List_Id;
2359 Handled_Stm_Seq : Node_Id;
2363 function Move_Activation_Chain return Node_Id;
2364 -- Construct a call to System.Tasking.Stages.Move_Activation_Chain
2366 -- From current activation chain
2367 -- To activation chain passed in by the caller
2368 -- New_Master master passed in by the caller
2370 function Move_Final_List return Node_Id;
2371 -- Construct call to System.Finalization_Implementation.Move_Final_List
2374 -- From finalization list of the return statement
2375 -- To finalization list passed in by the caller
2377 ---------------------------
2378 -- Move_Activation_Chain --
2379 ---------------------------
2381 function Move_Activation_Chain return Node_Id is
2382 Activation_Chain_Formal : constant Entity_Id :=
2383 Build_In_Place_Formal
2384 (Parent_Function, BIP_Activation_Chain);
2385 To : constant Node_Id :=
2387 (Activation_Chain_Formal, Loc);
2388 Master_Formal : constant Entity_Id :=
2389 Build_In_Place_Formal
2390 (Parent_Function, BIP_Master);
2391 New_Master : constant Node_Id :=
2392 New_Reference_To (Master_Formal, Loc);
2394 Chain_Entity : Entity_Id;
2398 Chain_Entity := First_Entity (Return_Statement_Entity (N));
2399 while Chars (Chain_Entity) /= Name_uChain loop
2400 Chain_Entity := Next_Entity (Chain_Entity);
2404 Make_Attribute_Reference (Loc,
2405 Prefix => New_Reference_To (Chain_Entity, Loc),
2406 Attribute_Name => Name_Unrestricted_Access);
2407 -- ??? Not clear why "Make_Identifier (Loc, Name_uChain)" doesn't
2408 -- work, instead of "New_Reference_To (Chain_Entity, Loc)" above.
2411 Make_Procedure_Call_Statement (Loc,
2412 Name => New_Reference_To (RTE (RE_Move_Activation_Chain), Loc),
2413 Parameter_Associations => New_List (From, To, New_Master));
2414 end Move_Activation_Chain;
2416 ---------------------
2417 -- Move_Final_List --
2418 ---------------------
2420 function Move_Final_List return Node_Id is
2421 Flist : constant Entity_Id :=
2422 Finalization_Chain_Entity (Return_Statement_Entity (N));
2424 From : constant Node_Id := New_Reference_To (Flist, Loc);
2426 Caller_Final_List : constant Entity_Id :=
2427 Build_In_Place_Formal
2428 (Parent_Function, BIP_Final_List);
2430 To : constant Node_Id := New_Reference_To (Caller_Final_List, Loc);
2433 -- Catch cases where a finalization chain entity has not been
2434 -- associated with the return statement entity.
2436 pragma Assert (Present (Flist));
2438 -- Build required call
2441 Make_If_Statement (Loc,
2444 Left_Opnd => New_Copy (From),
2445 Right_Opnd => New_Node (N_Null, Loc)),
2448 Make_Procedure_Call_Statement (Loc,
2449 Name => New_Reference_To (RTE (RE_Move_Final_List), Loc),
2450 Parameter_Associations => New_List (From, To))));
2451 end Move_Final_List;
2453 -- Start of processing for Expand_N_Extended_Return_Statement
2456 if Nkind (Return_Object_Decl) = N_Object_Declaration then
2457 Exp := Expression (Return_Object_Decl);
2462 Handled_Stm_Seq := Handled_Statement_Sequence (N);
2464 -- Build a simple_return_statement that returns the return object when
2465 -- there is a statement sequence, or no expression, or the result will
2466 -- be built in place. Note however that we currently do this for all
2467 -- composite cases, even though nonlimited composite results are not yet
2468 -- built in place (though we plan to do so eventually).
2470 if Present (Handled_Stm_Seq)
2471 or else Is_Composite_Type (Etype (Parent_Function))
2474 if No (Handled_Stm_Seq) then
2475 Statements := New_List;
2477 -- If the extended return has a handled statement sequence, then wrap
2478 -- it in a block and use the block as the first statement.
2482 New_List (Make_Block_Statement (Loc,
2483 Declarations => New_List,
2484 Handled_Statement_Sequence => Handled_Stm_Seq));
2487 -- If control gets past the above Statements, we have successfully
2488 -- completed the return statement. If the result type has controlled
2489 -- parts and the return is for a build-in-place function, then we
2490 -- call Move_Final_List to transfer responsibility for finalization
2491 -- of the return object to the caller. An alternative would be to
2492 -- declare a Success flag in the function, initialize it to False,
2493 -- and set it to True here. Then move the Move_Final_List call into
2494 -- the cleanup code, and check Success. If Success then make a call
2495 -- to Move_Final_List else do finalization. Then we can remove the
2496 -- abort-deferral and the nulling-out of the From parameter from
2497 -- Move_Final_List. Note that the current method is not quite correct
2498 -- in the rather obscure case of a select-then-abort statement whose
2499 -- abortable part contains the return statement.
2501 -- We test the type of the expression as well as the return type
2502 -- of the function, because the latter may be a class-wide type
2503 -- which is always treated as controlled, while the expression itself
2504 -- has to have a definite type. The expression may be absent if a
2505 -- constrained aggregate has been expanded into component assignments
2506 -- so we have to check for this as well.
2508 if Is_Build_In_Place
2509 and then Controlled_Type (Etype (Parent_Function))
2511 if not Is_Class_Wide_Type (Etype (Parent_Function))
2514 and then Controlled_Type (Etype (Exp)))
2516 Append_To (Statements, Move_Final_List);
2520 -- Similarly to the above Move_Final_List, if the result type
2521 -- contains tasks, we call Move_Activation_Chain. Later, the cleanup
2522 -- code will call Complete_Master, which will terminate any
2523 -- unactivated tasks belonging to the return statement master. But
2524 -- Move_Activation_Chain updates their master to be that of the
2525 -- caller, so they will not be terminated unless the return statement
2526 -- completes unsuccessfully due to exception, abort, goto, or exit.
2527 -- As a formality, we test whether the function requires the result
2528 -- to be built in place, though that's necessarily true for the case
2529 -- of result types with task parts.
2531 if Is_Build_In_Place and Has_Task (Etype (Parent_Function)) then
2532 Append_To (Statements, Move_Activation_Chain);
2535 -- Build a simple_return_statement that returns the return object
2538 Make_Simple_Return_Statement (Loc,
2539 Expression => New_Occurrence_Of (Return_Object_Entity, Loc));
2540 Append_To (Statements, Return_Stm);
2543 Make_Handled_Sequence_Of_Statements (Loc, Statements);
2546 -- Case where we build a block
2548 if Present (Handled_Stm_Seq) then
2550 Make_Block_Statement (Loc,
2551 Declarations => Return_Object_Declarations (N),
2552 Handled_Statement_Sequence => Handled_Stm_Seq);
2554 -- We set the entity of the new block statement to be that of the
2555 -- return statement. This is necessary so that various fields, such
2556 -- as Finalization_Chain_Entity carry over from the return statement
2557 -- to the block. Note that this block is unusual, in that its entity
2558 -- is an E_Return_Statement rather than an E_Block.
2561 (Result, New_Occurrence_Of (Return_Statement_Entity (N), Loc));
2563 -- If the object decl was already rewritten as a renaming, then
2564 -- we don't want to do the object allocation and transformation of
2565 -- of the return object declaration to a renaming. This case occurs
2566 -- when the return object is initialized by a call to another
2567 -- build-in-place function, and that function is responsible for the
2568 -- allocation of the return object.
2570 if Is_Build_In_Place
2572 Nkind (Return_Object_Decl) = N_Object_Renaming_Declaration
2574 Set_By_Ref (Return_Stm); -- Return build-in-place results by ref
2576 elsif Is_Build_In_Place then
2578 -- Locate the implicit access parameter associated with the
2579 -- caller-supplied return object and convert the return
2580 -- statement's return object declaration to a renaming of a
2581 -- dereference of the access parameter. If the return object's
2582 -- declaration includes an expression that has not already been
2583 -- expanded as separate assignments, then add an assignment
2584 -- statement to ensure the return object gets initialized.
2587 -- Result : T [:= <expression>];
2594 -- Result : T renames FuncRA.all;
2595 -- [Result := <expression;]
2600 Return_Obj_Id : constant Entity_Id :=
2601 Defining_Identifier (Return_Object_Decl);
2602 Return_Obj_Typ : constant Entity_Id := Etype (Return_Obj_Id);
2603 Return_Obj_Expr : constant Node_Id :=
2604 Expression (Return_Object_Decl);
2605 Result_Subt : constant Entity_Id :=
2606 Etype (Parent_Function);
2607 Constr_Result : constant Boolean :=
2608 Is_Constrained (Result_Subt);
2609 Obj_Alloc_Formal : Entity_Id;
2610 Object_Access : Entity_Id;
2611 Obj_Acc_Deref : Node_Id;
2612 Init_Assignment : Node_Id := Empty;
2615 -- Build-in-place results must be returned by reference
2617 Set_By_Ref (Return_Stm);
2619 -- Retrieve the implicit access parameter passed by the caller
2622 Build_In_Place_Formal (Parent_Function, BIP_Object_Access);
2624 -- If the return object's declaration includes an expression
2625 -- and the declaration isn't marked as No_Initialization, then
2626 -- we need to generate an assignment to the object and insert
2627 -- it after the declaration before rewriting it as a renaming
2628 -- (otherwise we'll lose the initialization).
2630 if Present (Return_Obj_Expr)
2631 and then not No_Initialization (Return_Object_Decl)
2634 Make_Assignment_Statement (Loc,
2635 Name => New_Reference_To (Return_Obj_Id, Loc),
2636 Expression => Relocate_Node (Return_Obj_Expr));
2637 Set_Etype (Name (Init_Assignment), Etype (Return_Obj_Id));
2638 Set_Assignment_OK (Name (Init_Assignment));
2639 Set_No_Ctrl_Actions (Init_Assignment);
2641 Set_Parent (Name (Init_Assignment), Init_Assignment);
2642 Set_Parent (Expression (Init_Assignment), Init_Assignment);
2644 Set_Expression (Return_Object_Decl, Empty);
2646 if Is_Class_Wide_Type (Etype (Return_Obj_Id))
2647 and then not Is_Class_Wide_Type
2648 (Etype (Expression (Init_Assignment)))
2650 Rewrite (Expression (Init_Assignment),
2651 Make_Type_Conversion (Loc,
2654 (Etype (Return_Obj_Id), Loc),
2656 Relocate_Node (Expression (Init_Assignment))));
2659 -- In the case of functions where the calling context can
2660 -- determine the form of allocation needed, initialization
2661 -- is done with each part of the if statement that handles
2662 -- the different forms of allocation (this is true for
2663 -- unconstrained and tagged result subtypes).
2666 and then not Is_Tagged_Type (Underlying_Type (Result_Subt))
2668 Insert_After (Return_Object_Decl, Init_Assignment);
2672 -- When the function's subtype is unconstrained, a run-time
2673 -- test is needed to determine the form of allocation to use
2674 -- for the return object. The function has an implicit formal
2675 -- parameter indicating this. If the BIP_Alloc_Form formal has
2676 -- the value one, then the caller has passed access to an
2677 -- existing object for use as the return object. If the value
2678 -- is two, then the return object must be allocated on the
2679 -- secondary stack. Otherwise, the object must be allocated in
2680 -- a storage pool (currently only supported for the global
2681 -- heap, user-defined storage pools TBD ???). We generate an
2682 -- if statement to test the implicit allocation formal and
2683 -- initialize a local access value appropriately, creating
2684 -- allocators in the secondary stack and global heap cases.
2685 -- The special formal also exists and must be tested when the
2686 -- function has a tagged result, even when the result subtype
2687 -- is constrained, because in general such functions can be
2688 -- called in dispatching contexts and must be handled similarly
2689 -- to functions with a class-wide result.
2691 if not Constr_Result
2692 or else Is_Tagged_Type (Underlying_Type (Result_Subt))
2695 Build_In_Place_Formal (Parent_Function, BIP_Alloc_Form);
2698 Ref_Type : Entity_Id;
2699 Ptr_Type_Decl : Node_Id;
2700 Alloc_Obj_Id : Entity_Id;
2701 Alloc_Obj_Decl : Node_Id;
2702 Alloc_If_Stmt : Node_Id;
2703 SS_Allocator : Node_Id;
2704 Heap_Allocator : Node_Id;
2707 -- Reuse the itype created for the function's implicit
2708 -- access formal. This avoids the need to create a new
2709 -- access type here, plus it allows assigning the access
2710 -- formal directly without applying a conversion.
2712 -- Ref_Type := Etype (Object_Access);
2714 -- Create an access type designating the function's
2718 Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
2721 Make_Full_Type_Declaration (Loc,
2722 Defining_Identifier => Ref_Type,
2724 Make_Access_To_Object_Definition (Loc,
2725 All_Present => True,
2726 Subtype_Indication =>
2727 New_Reference_To (Return_Obj_Typ, Loc)));
2729 Insert_Before (Return_Object_Decl, Ptr_Type_Decl);
2731 -- Create an access object that will be initialized to an
2732 -- access value denoting the return object, either coming
2733 -- from an implicit access value passed in by the caller
2734 -- or from the result of an allocator.
2737 Make_Defining_Identifier (Loc,
2738 Chars => New_Internal_Name ('R'));
2739 Set_Etype (Alloc_Obj_Id, Ref_Type);
2742 Make_Object_Declaration (Loc,
2743 Defining_Identifier => Alloc_Obj_Id,
2744 Object_Definition => New_Reference_To
2747 Insert_Before (Return_Object_Decl, Alloc_Obj_Decl);
2749 -- Create allocators for both the secondary stack and
2750 -- global heap. If there's an initialization expression,
2751 -- then create these as initialized allocators.
2753 if Present (Return_Obj_Expr)
2754 and then not No_Initialization (Return_Object_Decl)
2757 Make_Allocator (Loc,
2759 Make_Qualified_Expression (Loc,
2761 New_Reference_To (Return_Obj_Typ, Loc),
2763 New_Copy_Tree (Return_Obj_Expr)));
2765 SS_Allocator := New_Copy_Tree (Heap_Allocator);
2768 -- If the function returns a class-wide type we cannot
2769 -- use the return type for the allocator. Instead we
2770 -- use the type of the expression, which must be an
2771 -- aggregate of a definite type.
2773 if Is_Class_Wide_Type (Return_Obj_Typ) then
2775 Make_Allocator (Loc,
2777 (Etype (Return_Obj_Expr), Loc));
2780 Make_Allocator (Loc,
2781 New_Reference_To (Return_Obj_Typ, Loc));
2784 -- If the object requires default initialization then
2785 -- that will happen later following the elaboration of
2786 -- the object renaming. If we don't turn it off here
2787 -- then the object will be default initialized twice.
2789 Set_No_Initialization (Heap_Allocator);
2791 SS_Allocator := New_Copy_Tree (Heap_Allocator);
2795 (SS_Allocator, RTE (RE_SS_Pool));
2796 Set_Procedure_To_Call
2797 (SS_Allocator, RTE (RE_SS_Allocate));
2799 -- The allocator is returned on the secondary stack,
2800 -- so indicate that the function return, as well as
2801 -- the block that encloses the allocator, must not
2802 -- release it. The flags must be set now because the
2803 -- decision to use the secondary stack is done very
2804 -- late in the course of expanding the return statement,
2805 -- past the point where these flags are normally set.
2807 Set_Sec_Stack_Needed_For_Return (Parent_Function);
2808 Set_Sec_Stack_Needed_For_Return
2809 (Return_Statement_Entity (N));
2810 Set_Uses_Sec_Stack (Parent_Function);
2811 Set_Uses_Sec_Stack (Return_Statement_Entity (N));
2813 -- Create an if statement to test the BIP_Alloc_Form
2814 -- formal and initialize the access object to either the
2815 -- BIP_Object_Access formal (BIP_Alloc_Form = 0), the
2816 -- result of allocating the object in the secondary stack
2817 -- (BIP_Alloc_Form = 1), or else an allocator to create
2818 -- the return object in the heap (BIP_Alloc_Form = 2).
2820 -- ??? An unchecked type conversion must be made in the
2821 -- case of assigning the access object formal to the
2822 -- local access object, because a normal conversion would
2823 -- be illegal in some cases (such as converting access-
2824 -- to-unconstrained to access-to-constrained), but the
2825 -- the unchecked conversion will presumably fail to work
2826 -- right in just such cases. It's not clear at all how to
2830 Make_If_Statement (Loc,
2834 New_Reference_To (Obj_Alloc_Formal, Loc),
2836 Make_Integer_Literal (Loc,
2837 UI_From_Int (BIP_Allocation_Form'Pos
2838 (Caller_Allocation)))),
2840 New_List (Make_Assignment_Statement (Loc,
2843 (Alloc_Obj_Id, Loc),
2845 Make_Unchecked_Type_Conversion (Loc,
2847 New_Reference_To (Ref_Type, Loc),
2850 (Object_Access, Loc)))),
2852 New_List (Make_Elsif_Part (Loc,
2857 (Obj_Alloc_Formal, Loc),
2859 Make_Integer_Literal (Loc,
2861 BIP_Allocation_Form'Pos
2862 (Secondary_Stack)))),
2865 (Make_Assignment_Statement (Loc,
2868 (Alloc_Obj_Id, Loc),
2872 New_List (Make_Assignment_Statement (Loc,
2875 (Alloc_Obj_Id, Loc),
2879 -- If a separate initialization assignment was created
2880 -- earlier, append that following the assignment of the
2881 -- implicit access formal to the access object, to ensure
2882 -- that the return object is initialized in that case.
2883 -- In this situation, the target of the assignment must
2884 -- be rewritten to denote a derference of the access to
2885 -- the return object passed in by the caller.
2887 if Present (Init_Assignment) then
2888 Rewrite (Name (Init_Assignment),
2889 Make_Explicit_Dereference (Loc,
2890 Prefix => New_Reference_To (Alloc_Obj_Id, Loc)));
2892 (Name (Init_Assignment), Etype (Return_Obj_Id));
2895 (Then_Statements (Alloc_If_Stmt),
2899 Insert_Before (Return_Object_Decl, Alloc_If_Stmt);
2901 -- Remember the local access object for use in the
2902 -- dereference of the renaming created below.
2904 Object_Access := Alloc_Obj_Id;
2908 -- Replace the return object declaration with a renaming of a
2909 -- dereference of the access value designating the return
2913 Make_Explicit_Dereference (Loc,
2914 Prefix => New_Reference_To (Object_Access, Loc));
2916 Rewrite (Return_Object_Decl,
2917 Make_Object_Renaming_Declaration (Loc,
2918 Defining_Identifier => Return_Obj_Id,
2919 Access_Definition => Empty,
2920 Subtype_Mark => New_Occurrence_Of
2921 (Return_Obj_Typ, Loc),
2922 Name => Obj_Acc_Deref));
2924 Set_Renamed_Object (Return_Obj_Id, Obj_Acc_Deref);
2928 -- Case where we do not build a block
2931 -- We're about to drop Return_Object_Declarations on the floor, so
2932 -- we need to insert it, in case it got expanded into useful code.
2934 Insert_List_Before (N, Return_Object_Declarations (N));
2936 -- Build simple_return_statement that returns the expression directly
2938 Return_Stm := Make_Simple_Return_Statement (Loc, Expression => Exp);
2940 Result := Return_Stm;
2943 -- Set the flag to prevent infinite recursion
2945 Set_Comes_From_Extended_Return_Statement (Return_Stm);
2947 Rewrite (N, Result);
2949 end Expand_N_Extended_Return_Statement;
2951 -----------------------------
2952 -- Expand_N_Goto_Statement --
2953 -----------------------------
2955 -- Add poll before goto if polling active
2957 procedure Expand_N_Goto_Statement (N : Node_Id) is
2959 Generate_Poll_Call (N);
2960 end Expand_N_Goto_Statement;
2962 ---------------------------
2963 -- Expand_N_If_Statement --
2964 ---------------------------
2966 -- First we deal with the case of C and Fortran convention boolean values,
2967 -- with zero/non-zero semantics.
2969 -- Second, we deal with the obvious rewriting for the cases where the
2970 -- condition of the IF is known at compile time to be True or False.
2972 -- Third, we remove elsif parts which have non-empty Condition_Actions
2973 -- and rewrite as independent if statements. For example:
2984 -- <<condition actions of y>>
2990 -- This rewriting is needed if at least one elsif part has a non-empty
2991 -- Condition_Actions list. We also do the same processing if there is a
2992 -- constant condition in an elsif part (in conjunction with the first
2993 -- processing step mentioned above, for the recursive call made to deal
2994 -- with the created inner if, this deals with properly optimizing the
2995 -- cases of constant elsif conditions).
2997 procedure Expand_N_If_Statement (N : Node_Id) is
2998 Loc : constant Source_Ptr := Sloc (N);
3003 Warn_If_Deleted : constant Boolean :=
3004 Warn_On_Deleted_Code and then Comes_From_Source (N);
3005 -- Indicates whether we want warnings when we delete branches of the
3006 -- if statement based on constant condition analysis. We never want
3007 -- these warnings for expander generated code.
3010 Adjust_Condition (Condition (N));
3012 -- The following loop deals with constant conditions for the IF. We
3013 -- need a loop because as we eliminate False conditions, we grab the
3014 -- first elsif condition and use it as the primary condition.
3016 while Compile_Time_Known_Value (Condition (N)) loop
3018 -- If condition is True, we can simply rewrite the if statement now
3019 -- by replacing it by the series of then statements.
3021 if Is_True (Expr_Value (Condition (N))) then
3023 -- All the else parts can be killed
3025 Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted);
3026 Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted);
3028 Hed := Remove_Head (Then_Statements (N));
3029 Insert_List_After (N, Then_Statements (N));
3033 -- If condition is False, then we can delete the condition and
3034 -- the Then statements
3037 -- We do not delete the condition if constant condition warnings
3038 -- are enabled, since otherwise we end up deleting the desired
3039 -- warning. Of course the backend will get rid of this True/False
3040 -- test anyway, so nothing is lost here.
3042 if not Constant_Condition_Warnings then
3043 Kill_Dead_Code (Condition (N));
3046 Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted);
3048 -- If there are no elsif statements, then we simply replace the
3049 -- entire if statement by the sequence of else statements.
3051 if No (Elsif_Parts (N)) then
3052 if No (Else_Statements (N))
3053 or else Is_Empty_List (Else_Statements (N))
3056 Make_Null_Statement (Sloc (N)));
3058 Hed := Remove_Head (Else_Statements (N));
3059 Insert_List_After (N, Else_Statements (N));
3065 -- If there are elsif statements, the first of them becomes the
3066 -- if/then section of the rebuilt if statement This is the case
3067 -- where we loop to reprocess this copied condition.
3070 Hed := Remove_Head (Elsif_Parts (N));
3071 Insert_Actions (N, Condition_Actions (Hed));
3072 Set_Condition (N, Condition (Hed));
3073 Set_Then_Statements (N, Then_Statements (Hed));
3075 -- Hed might have been captured as the condition determining
3076 -- the current value for an entity. Now it is detached from
3077 -- the tree, so a Current_Value pointer in the condition might
3078 -- need to be updated.
3080 Set_Current_Value_Condition (N);
3082 if Is_Empty_List (Elsif_Parts (N)) then
3083 Set_Elsif_Parts (N, No_List);
3089 -- Loop through elsif parts, dealing with constant conditions and
3090 -- possible expression actions that are present.
3092 if Present (Elsif_Parts (N)) then
3093 E := First (Elsif_Parts (N));
3094 while Present (E) loop
3095 Adjust_Condition (Condition (E));
3097 -- If there are condition actions, then rewrite the if statement
3098 -- as indicated above. We also do the same rewrite for a True or
3099 -- False condition. The further processing of this constant
3100 -- condition is then done by the recursive call to expand the
3101 -- newly created if statement
3103 if Present (Condition_Actions (E))
3104 or else Compile_Time_Known_Value (Condition (E))
3106 -- Note this is not an implicit if statement, since it is part
3107 -- of an explicit if statement in the source (or of an implicit
3108 -- if statement that has already been tested).
3111 Make_If_Statement (Sloc (E),
3112 Condition => Condition (E),
3113 Then_Statements => Then_Statements (E),
3114 Elsif_Parts => No_List,
3115 Else_Statements => Else_Statements (N));
3117 -- Elsif parts for new if come from remaining elsif's of parent
3119 while Present (Next (E)) loop
3120 if No (Elsif_Parts (New_If)) then
3121 Set_Elsif_Parts (New_If, New_List);
3124 Append (Remove_Next (E), Elsif_Parts (New_If));
3127 Set_Else_Statements (N, New_List (New_If));
3129 if Present (Condition_Actions (E)) then
3130 Insert_List_Before (New_If, Condition_Actions (E));
3135 if Is_Empty_List (Elsif_Parts (N)) then
3136 Set_Elsif_Parts (N, No_List);
3142 -- No special processing for that elsif part, move to next
3150 -- Some more optimizations applicable if we still have an IF statement
3152 if Nkind (N) /= N_If_Statement then
3156 -- Another optimization, special cases that can be simplified
3158 -- if expression then
3164 -- can be changed to:
3166 -- return expression;
3170 -- if expression then
3176 -- can be changed to:
3178 -- return not (expression);
3180 if Nkind (N) = N_If_Statement
3181 and then No (Elsif_Parts (N))
3182 and then Present (Else_Statements (N))
3183 and then List_Length (Then_Statements (N)) = 1
3184 and then List_Length (Else_Statements (N)) = 1
3187 Then_Stm : constant Node_Id := First (Then_Statements (N));
3188 Else_Stm : constant Node_Id := First (Else_Statements (N));
3191 if Nkind (Then_Stm) = N_Simple_Return_Statement
3193 Nkind (Else_Stm) = N_Simple_Return_Statement
3196 Then_Expr : constant Node_Id := Expression (Then_Stm);
3197 Else_Expr : constant Node_Id := Expression (Else_Stm);
3200 if Nkind (Then_Expr) = N_Identifier
3202 Nkind (Else_Expr) = N_Identifier
3204 if Entity (Then_Expr) = Standard_True
3205 and then Entity (Else_Expr) = Standard_False
3208 Make_Simple_Return_Statement (Loc,
3209 Expression => Relocate_Node (Condition (N))));
3213 elsif Entity (Then_Expr) = Standard_False
3214 and then Entity (Else_Expr) = Standard_True
3217 Make_Simple_Return_Statement (Loc,
3220 Right_Opnd => Relocate_Node (Condition (N)))));
3229 end Expand_N_If_Statement;
3231 -----------------------------
3232 -- Expand_N_Loop_Statement --
3233 -----------------------------
3235 -- 1. Deal with while condition for C/Fortran boolean
3236 -- 2. Deal with loops with a non-standard enumeration type range
3237 -- 3. Deal with while loops where Condition_Actions is set
3238 -- 4. Insert polling call if required
3240 procedure Expand_N_Loop_Statement (N : Node_Id) is
3241 Loc : constant Source_Ptr := Sloc (N);
3242 Isc : constant Node_Id := Iteration_Scheme (N);
3245 if Present (Isc) then
3246 Adjust_Condition (Condition (Isc));
3249 if Is_Non_Empty_List (Statements (N)) then
3250 Generate_Poll_Call (First (Statements (N)));
3253 -- Nothing more to do for plain loop with no iteration scheme
3259 -- Note: we do not have to worry about validity chekcing of the for loop
3260 -- range bounds here, since they were frozen with constant declarations
3261 -- and it is during that process that the validity checking is done.
3263 -- Handle the case where we have a for loop with the range type being an
3264 -- enumeration type with non-standard representation. In this case we
3267 -- for x in [reverse] a .. b loop
3273 -- for xP in [reverse] integer
3274 -- range etype'Pos (a) .. etype'Pos (b) loop
3276 -- x : constant etype := Pos_To_Rep (xP);
3282 if Present (Loop_Parameter_Specification (Isc)) then
3284 LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
3285 Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
3286 Ltype : constant Entity_Id := Etype (Loop_Id);
3287 Btype : constant Entity_Id := Base_Type (Ltype);
3292 if not Is_Enumeration_Type (Btype)
3293 or else No (Enum_Pos_To_Rep (Btype))
3299 Make_Defining_Identifier (Loc,
3300 Chars => New_External_Name (Chars (Loop_Id), 'P'));
3302 -- If the type has a contiguous representation, successive values
3303 -- can be generated as offsets from the first literal.
3305 if Has_Contiguous_Rep (Btype) then
3307 Unchecked_Convert_To (Btype,
3310 Make_Integer_Literal (Loc,
3311 Enumeration_Rep (First_Literal (Btype))),
3312 Right_Opnd => New_Reference_To (New_Id, Loc)));
3314 -- Use the constructed array Enum_Pos_To_Rep
3317 Make_Indexed_Component (Loc,
3318 Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc),
3319 Expressions => New_List (New_Reference_To (New_Id, Loc)));
3323 Make_Loop_Statement (Loc,
3324 Identifier => Identifier (N),
3327 Make_Iteration_Scheme (Loc,
3328 Loop_Parameter_Specification =>
3329 Make_Loop_Parameter_Specification (Loc,
3330 Defining_Identifier => New_Id,
3331 Reverse_Present => Reverse_Present (LPS),
3333 Discrete_Subtype_Definition =>
3334 Make_Subtype_Indication (Loc,
3337 New_Reference_To (Standard_Natural, Loc),
3340 Make_Range_Constraint (Loc,
3345 Make_Attribute_Reference (Loc,
3347 New_Reference_To (Btype, Loc),
3349 Attribute_Name => Name_Pos,
3351 Expressions => New_List (
3353 (Type_Low_Bound (Ltype)))),
3356 Make_Attribute_Reference (Loc,
3358 New_Reference_To (Btype, Loc),
3360 Attribute_Name => Name_Pos,
3362 Expressions => New_List (
3364 (Type_High_Bound (Ltype))))))))),
3366 Statements => New_List (
3367 Make_Block_Statement (Loc,
3368 Declarations => New_List (
3369 Make_Object_Declaration (Loc,
3370 Defining_Identifier => Loop_Id,
3371 Constant_Present => True,
3372 Object_Definition => New_Reference_To (Ltype, Loc),
3373 Expression => Expr)),
3375 Handled_Statement_Sequence =>
3376 Make_Handled_Sequence_Of_Statements (Loc,
3377 Statements => Statements (N)))),
3379 End_Label => End_Label (N)));
3383 -- Second case, if we have a while loop with Condition_Actions set, then
3384 -- we change it into a plain loop:
3393 -- <<condition actions>>
3399 and then Present (Condition_Actions (Isc))
3406 Make_Exit_Statement (Sloc (Condition (Isc)),
3408 Make_Op_Not (Sloc (Condition (Isc)),
3409 Right_Opnd => Condition (Isc)));
3411 Prepend (ES, Statements (N));
3412 Insert_List_Before (ES, Condition_Actions (Isc));
3414 -- This is not an implicit loop, since it is generated in response
3415 -- to the loop statement being processed. If this is itself
3416 -- implicit, the restriction has already been checked. If not,
3417 -- it is an explicit loop.
3420 Make_Loop_Statement (Sloc (N),
3421 Identifier => Identifier (N),
3422 Statements => Statements (N),
3423 End_Label => End_Label (N)));
3428 end Expand_N_Loop_Statement;
3430 --------------------------------------
3431 -- Expand_N_Simple_Return_Statement --
3432 --------------------------------------
3434 procedure Expand_N_Simple_Return_Statement (N : Node_Id) is
3436 -- Distinguish the function and non-function cases:
3438 case Ekind (Return_Applies_To (Return_Statement_Entity (N))) is
3441 E_Generic_Function =>
3442 Expand_Simple_Function_Return (N);
3445 E_Generic_Procedure |
3448 E_Return_Statement =>
3449 Expand_Non_Function_Return (N);
3452 raise Program_Error;
3456 when RE_Not_Available =>
3458 end Expand_N_Simple_Return_Statement;
3460 --------------------------------
3461 -- Expand_Non_Function_Return --
3462 --------------------------------
3464 procedure Expand_Non_Function_Return (N : Node_Id) is
3465 pragma Assert (No (Expression (N)));
3467 Loc : constant Source_Ptr := Sloc (N);
3468 Scope_Id : Entity_Id :=
3469 Return_Applies_To (Return_Statement_Entity (N));
3470 Kind : constant Entity_Kind := Ekind (Scope_Id);
3473 Goto_Stat : Node_Id;
3477 -- If it is a return from a procedure do no extra steps
3479 if Kind = E_Procedure or else Kind = E_Generic_Procedure then
3482 -- If it is a nested return within an extended one, replace it with a
3483 -- return of the previously declared return object.
3485 elsif Kind = E_Return_Statement then
3487 Make_Simple_Return_Statement (Loc,
3489 New_Occurrence_Of (First_Entity (Scope_Id), Loc)));
3490 Set_Comes_From_Extended_Return_Statement (N);
3491 Set_Return_Statement_Entity (N, Scope_Id);
3492 Expand_Simple_Function_Return (N);
3496 pragma Assert (Is_Entry (Scope_Id));
3498 -- Look at the enclosing block to see whether the return is from an
3499 -- accept statement or an entry body.
3501 for J in reverse 0 .. Scope_Stack.Last loop
3502 Scope_Id := Scope_Stack.Table (J).Entity;
3503 exit when Is_Concurrent_Type (Scope_Id);
3506 -- If it is a return from accept statement it is expanded as call to
3507 -- RTS Complete_Rendezvous and a goto to the end of the accept body.
3509 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
3510 -- Expand_N_Accept_Alternative in exp_ch9.adb)
3512 if Is_Task_Type (Scope_Id) then
3515 Make_Procedure_Call_Statement (Loc,
3516 Name => New_Reference_To
3517 (RTE (RE_Complete_Rendezvous), Loc));
3518 Insert_Before (N, Call);
3519 -- why not insert actions here???
3522 Acc_Stat := Parent (N);
3523 while Nkind (Acc_Stat) /= N_Accept_Statement loop
3524 Acc_Stat := Parent (Acc_Stat);
3527 Lab_Node := Last (Statements
3528 (Handled_Statement_Sequence (Acc_Stat)));
3530 Goto_Stat := Make_Goto_Statement (Loc,
3531 Name => New_Occurrence_Of
3532 (Entity (Identifier (Lab_Node)), Loc));
3534 Set_Analyzed (Goto_Stat);
3536 Rewrite (N, Goto_Stat);
3539 -- If it is a return from an entry body, put a Complete_Entry_Body call
3540 -- in front of the return.
3542 elsif Is_Protected_Type (Scope_Id) then
3544 Make_Procedure_Call_Statement (Loc,
3545 Name => New_Reference_To
3546 (RTE (RE_Complete_Entry_Body), Loc),
3547 Parameter_Associations => New_List
3548 (Make_Attribute_Reference (Loc,
3552 (Corresponding_Body (Parent (Scope_Id))),
3554 Attribute_Name => Name_Unchecked_Access)));
3556 Insert_Before (N, Call);
3559 end Expand_Non_Function_Return;
3561 -----------------------------------
3562 -- Expand_Simple_Function_Return --
3563 -----------------------------------
3565 -- The "simple" comes from the syntax rule simple_return_statement.
3566 -- The semantics are not at all simple!
3568 procedure Expand_Simple_Function_Return (N : Node_Id) is
3569 Loc : constant Source_Ptr := Sloc (N);
3571 Scope_Id : constant Entity_Id :=
3572 Return_Applies_To (Return_Statement_Entity (N));
3573 -- The function we are returning from
3575 R_Type : constant Entity_Id := Etype (Scope_Id);
3576 -- The result type of the function
3578 Utyp : constant Entity_Id := Underlying_Type (R_Type);
3580 Exp : constant Node_Id := Expression (N);
3581 pragma Assert (Present (Exp));
3583 Exptyp : constant Entity_Id := Etype (Exp);
3584 -- The type of the expression (not necessarily the same as R_Type)
3587 -- We rewrite "return <expression>;" to be:
3589 -- return _anon_ : <return_subtype> := <expression>
3591 -- The expansion produced by Expand_N_Extended_Return_Statement will
3592 -- contain simple return statements (for example, a block containing
3593 -- simple return of the return object), which brings us back here with
3594 -- Comes_From_Extended_Return_Statement set. To avoid infinite
3595 -- recursion, we do not transform into an extended return if
3596 -- Comes_From_Extended_Return_Statement is True.
3598 -- The reason for this design is that for Ada 2005 limited returns, we
3599 -- need to reify the return object, so we can build it "in place", and
3600 -- we need a block statement to hang finalization and tasking stuff.
3602 -- ??? In order to avoid disruption, we avoid translating to extended
3603 -- return except in the cases where we really need to (Ada 2005
3604 -- inherently limited). We would prefer eventually to do this
3605 -- translation in all cases except perhaps for the case of Ada 95
3606 -- inherently limited, in order to fully exercise the code in
3607 -- Expand_N_Extended_Return_Statement, and in order to do
3608 -- build-in-place for efficiency when it is not required.
3610 -- As before, we check the type of the return expression rather than the
3611 -- return type of the function, because the latter may be a limited
3612 -- class-wide interface type, which is not a limited type, even though
3613 -- the type of the expression may be.
3615 if not Comes_From_Extended_Return_Statement (N)
3616 and then Is_Inherently_Limited_Type (Etype (Expression (N)))
3617 and then Ada_Version >= Ada_05 -- ???
3618 and then not Debug_Flag_Dot_L
3621 Return_Object_Entity : constant Entity_Id :=
3622 Make_Defining_Identifier (Loc,
3623 New_Internal_Name ('R'));
3625 Subtype_Ind : constant Node_Id := New_Occurrence_Of (R_Type, Loc);
3627 Obj_Decl : constant Node_Id :=
3628 Make_Object_Declaration (Loc,
3629 Defining_Identifier => Return_Object_Entity,
3630 Object_Definition => Subtype_Ind,
3633 Ext : constant Node_Id := Make_Extended_Return_Statement (Loc,
3634 Return_Object_Declarations => New_List (Obj_Decl));
3643 -- Here we have a simple return statement that is part of the expansion
3644 -- of an extended return statement (either written by the user, or
3645 -- generated by the above code).
3647 -- Always normalize C/Fortran boolean result. This is not always needed,
3648 -- but it seems a good idea to minimize the passing around of non-
3649 -- normalized values, and in any case this handles the processing of
3650 -- barrier functions for protected types, which turn the condition into
3651 -- a return statement.
3653 if Is_Boolean_Type (Exptyp)
3654 and then Nonzero_Is_True (Exptyp)
3656 Adjust_Condition (Exp);
3657 Adjust_Result_Type (Exp, Exptyp);
3660 -- Do validity check if enabled for returns
3662 if Validity_Checks_On
3663 and then Validity_Check_Returns
3668 -- Check the result expression of a scalar function against the subtype
3669 -- of the function by inserting a conversion. This conversion must
3670 -- eventually be performed for other classes of types, but for now it's
3671 -- only done for scalars.
3674 if Is_Scalar_Type (Exptyp) then
3675 Rewrite (Exp, Convert_To (R_Type, Exp));
3679 -- Deal with returning variable length objects and controlled types
3681 -- Nothing to do if we are returning by reference, or this is not a
3682 -- type that requires special processing (indicated by the fact that
3683 -- it requires a cleanup scope for the secondary stack case).
3685 if Is_Inherently_Limited_Type (Exptyp)
3686 or else Is_Limited_Interface (Exptyp)
3690 elsif not Requires_Transient_Scope (R_Type) then
3692 -- Mutable records with no variable length components are not
3693 -- returned on the sec-stack, so we need to make sure that the
3694 -- backend will only copy back the size of the actual value, and not
3695 -- the maximum size. We create an actual subtype for this purpose.
3698 Ubt : constant Entity_Id := Underlying_Type (Base_Type (Exptyp));
3702 if Has_Discriminants (Ubt)
3703 and then not Is_Constrained (Ubt)
3704 and then not Has_Unchecked_Union (Ubt)
3706 Decl := Build_Actual_Subtype (Ubt, Exp);
3707 Ent := Defining_Identifier (Decl);
3708 Insert_Action (Exp, Decl);
3709 Rewrite (Exp, Unchecked_Convert_To (Ent, Exp));
3710 Analyze_And_Resolve (Exp);
3714 -- Here if secondary stack is used
3717 -- Make sure that no surrounding block will reclaim the secondary
3718 -- stack on which we are going to put the result. Not only may this
3719 -- introduce secondary stack leaks but worse, if the reclamation is
3720 -- done too early, then the result we are returning may get
3727 while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop
3728 Set_Sec_Stack_Needed_For_Return (S, True);
3729 S := Enclosing_Dynamic_Scope (S);
3733 -- Optimize the case where the result is a function call. In this
3734 -- case either the result is already on the secondary stack, or is
3735 -- already being returned with the stack pointer depressed and no
3736 -- further processing is required except to set the By_Ref flag to
3737 -- ensure that gigi does not attempt an extra unnecessary copy.
3738 -- (actually not just unnecessary but harmfully wrong in the case
3739 -- of a controlled type, where gigi does not know how to do a copy).
3740 -- To make up for a gcc 2.8.1 deficiency (???), we perform
3741 -- the copy for array types if the constrained status of the
3742 -- target type is different from that of the expression.
3744 if Requires_Transient_Scope (Exptyp)
3746 (not Is_Array_Type (Exptyp)
3747 or else Is_Constrained (Exptyp) = Is_Constrained (R_Type)
3748 or else CW_Or_Controlled_Type (Utyp))
3749 and then Nkind (Exp) = N_Function_Call
3753 -- Remove side effects from the expression now so that other parts
3754 -- of the expander do not have to reanalyze this node without this
3757 Rewrite (Exp, Duplicate_Subexpr_No_Checks (Exp));
3759 -- For controlled types, do the allocation on the secondary stack
3760 -- manually in order to call adjust at the right time:
3762 -- type Anon1 is access R_Type;
3763 -- for Anon1'Storage_pool use ss_pool;
3764 -- Anon2 : anon1 := new R_Type'(expr);
3765 -- return Anon2.all;
3767 -- We do the same for classwide types that are not potentially
3768 -- controlled (by the virtue of restriction No_Finalization) because
3769 -- gigi is not able to properly allocate class-wide types.
3771 elsif CW_Or_Controlled_Type (Utyp) then
3773 Loc : constant Source_Ptr := Sloc (N);
3774 Temp : constant Entity_Id :=
3775 Make_Defining_Identifier (Loc,
3776 Chars => New_Internal_Name ('R'));
3777 Acc_Typ : constant Entity_Id :=
3778 Make_Defining_Identifier (Loc,
3779 Chars => New_Internal_Name ('A'));
3780 Alloc_Node : Node_Id;
3783 Set_Ekind (Acc_Typ, E_Access_Type);
3785 Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool));
3788 Make_Allocator (Loc,
3790 Make_Qualified_Expression (Loc,
3791 Subtype_Mark => New_Reference_To (Etype (Exp), Loc),
3792 Expression => Relocate_Node (Exp)));
3794 Insert_List_Before_And_Analyze (N, New_List (
3795 Make_Full_Type_Declaration (Loc,
3796 Defining_Identifier => Acc_Typ,
3798 Make_Access_To_Object_Definition (Loc,
3799 Subtype_Indication =>
3800 New_Reference_To (R_Type, Loc))),
3802 Make_Object_Declaration (Loc,
3803 Defining_Identifier => Temp,
3804 Object_Definition => New_Reference_To (Acc_Typ, Loc),
3805 Expression => Alloc_Node)));
3808 Make_Explicit_Dereference (Loc,
3809 Prefix => New_Reference_To (Temp, Loc)));
3811 Analyze_And_Resolve (Exp, R_Type);
3814 -- Otherwise use the gigi mechanism to allocate result on the
3818 Set_Storage_Pool (N, RTE (RE_SS_Pool));
3820 -- If we are generating code for the VM do not use
3821 -- SS_Allocate since everything is heap-allocated anyway.
3823 if VM_Target = No_VM then
3824 Set_Procedure_To_Call (N, RTE (RE_SS_Allocate));
3829 -- Implement the rules of 6.5(8-10), which require a tag check in the
3830 -- case of a limited tagged return type, and tag reassignment for
3831 -- nonlimited tagged results. These actions are needed when the return
3832 -- type is a specific tagged type and the result expression is a
3833 -- conversion or a formal parameter, because in that case the tag of the
3834 -- expression might differ from the tag of the specific result type.
3836 if Is_Tagged_Type (Utyp)
3837 and then not Is_Class_Wide_Type (Utyp)
3838 and then (Nkind (Exp) = N_Type_Conversion
3839 or else Nkind (Exp) = N_Unchecked_Type_Conversion
3840 or else (Is_Entity_Name (Exp)
3841 and then Ekind (Entity (Exp)) in Formal_Kind))
3843 -- When the return type is limited, perform a check that the
3844 -- tag of the result is the same as the tag of the return type.
3846 if Is_Limited_Type (R_Type) then
3848 Make_Raise_Constraint_Error (Loc,
3852 Make_Selected_Component (Loc,
3853 Prefix => Duplicate_Subexpr (Exp),
3855 New_Reference_To (First_Tag_Component (Utyp), Loc)),
3857 Unchecked_Convert_To (RTE (RE_Tag),
3860 (Access_Disp_Table (Base_Type (Utyp)))),
3862 Reason => CE_Tag_Check_Failed));
3864 -- If the result type is a specific nonlimited tagged type, then we
3865 -- have to ensure that the tag of the result is that of the result
3866 -- type. This is handled by making a copy of the expression in the
3867 -- case where it might have a different tag, namely when the
3868 -- expression is a conversion or a formal parameter. We create a new
3869 -- object of the result type and initialize it from the expression,
3870 -- which will implicitly force the tag to be set appropriately.
3874 Result_Id : constant Entity_Id :=
3875 Make_Defining_Identifier (Loc,
3876 Chars => New_Internal_Name ('R'));
3877 Result_Exp : constant Node_Id :=
3878 New_Reference_To (Result_Id, Loc);
3879 Result_Obj : constant Node_Id :=
3880 Make_Object_Declaration (Loc,
3881 Defining_Identifier => Result_Id,
3882 Object_Definition =>
3883 New_Reference_To (R_Type, Loc),
3884 Constant_Present => True,
3885 Expression => Relocate_Node (Exp));
3888 Set_Assignment_OK (Result_Obj);
3889 Insert_Action (Exp, Result_Obj);
3891 Rewrite (Exp, Result_Exp);
3892 Analyze_And_Resolve (Exp, R_Type);
3896 -- Ada 2005 (AI-344): If the result type is class-wide, then insert
3897 -- a check that the level of the return expression's underlying type
3898 -- is not deeper than the level of the master enclosing the function.
3899 -- Always generate the check when the type of the return expression
3900 -- is class-wide, when it's a type conversion, or when it's a formal
3901 -- parameter. Otherwise, suppress the check in the case where the
3902 -- return expression has a specific type whose level is known not to
3903 -- be statically deeper than the function's result type.
3905 -- Note: accessibility check is skipped in the VM case, since there
3906 -- does not seem to be any practical way to implement this check.
3908 elsif Ada_Version >= Ada_05
3909 and then VM_Target = No_VM
3910 and then Is_Class_Wide_Type (R_Type)
3911 and then not Scope_Suppress (Accessibility_Check)
3913 (Is_Class_Wide_Type (Etype (Exp))
3914 or else Nkind (Exp) = N_Type_Conversion
3915 or else Nkind (Exp) = N_Unchecked_Type_Conversion
3916 or else (Is_Entity_Name (Exp)
3917 and then Ekind (Entity (Exp)) in Formal_Kind)
3918 or else Scope_Depth (Enclosing_Dynamic_Scope (Etype (Exp))) >
3919 Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))
3925 -- Ada 2005 (AI-251): In class-wide interface objects we displace
3926 -- "this" to reference the base of the object --- required to get
3927 -- access to the TSD of the object.
3929 if Is_Class_Wide_Type (Etype (Exp))
3930 and then Is_Interface (Etype (Exp))
3931 and then Nkind (Exp) = N_Explicit_Dereference
3934 Make_Explicit_Dereference (Loc,
3935 Unchecked_Convert_To (RTE (RE_Tag_Ptr),
3936 Make_Function_Call (Loc,
3937 Name => New_Reference_To (RTE (RE_Base_Address), Loc),
3938 Parameter_Associations => New_List (
3939 Unchecked_Convert_To (RTE (RE_Address),
3940 Duplicate_Subexpr (Prefix (Exp)))))));
3943 Make_Attribute_Reference (Loc,
3944 Prefix => Duplicate_Subexpr (Exp),
3945 Attribute_Name => Name_Tag);
3949 Make_Raise_Program_Error (Loc,
3953 Build_Get_Access_Level (Loc, Tag_Node),
3955 Make_Integer_Literal (Loc,
3956 Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))),
3957 Reason => PE_Accessibility_Check_Failed));
3960 end Expand_Simple_Function_Return;
3962 ------------------------------
3963 -- Make_Tag_Ctrl_Assignment --
3964 ------------------------------
3966 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is
3967 Loc : constant Source_Ptr := Sloc (N);
3968 L : constant Node_Id := Name (N);
3969 T : constant Entity_Id := Underlying_Type (Etype (L));
3971 Ctrl_Act : constant Boolean := Controlled_Type (T)
3972 and then not No_Ctrl_Actions (N);
3974 Save_Tag : constant Boolean := Is_Tagged_Type (T)
3975 and then not No_Ctrl_Actions (N)
3976 and then VM_Target = No_VM;
3977 -- Tags are not saved and restored when VM_Target because VM tags are
3978 -- represented implicitly in objects.
3981 Tag_Tmp : Entity_Id;
3983 Prev_Tmp : Entity_Id;
3984 Next_Tmp : Entity_Id;
3990 -- Finalize the target of the assignment when controlled.
3991 -- We have two exceptions here:
3993 -- 1. If we are in an init proc since it is an initialization
3994 -- more than an assignment
3996 -- 2. If the left-hand side is a temporary that was not initialized
3997 -- (or the parent part of a temporary since it is the case in
3998 -- extension aggregates). Such a temporary does not come from
3999 -- source. We must examine the original node for the prefix, because
4000 -- it may be a component of an entry formal, in which case it has
4001 -- been rewritten and does not appear to come from source either.
4003 -- Case of init proc
4005 if not Ctrl_Act then
4008 -- The left hand side is an uninitialized temporary
4010 elsif Nkind (L) = N_Type_Conversion
4011 and then Is_Entity_Name (Expression (L))
4012 and then No_Initialization (Parent (Entity (Expression (L))))
4016 Append_List_To (Res,
4018 Ref => Duplicate_Subexpr_No_Checks (L),
4020 With_Detach => New_Reference_To (Standard_False, Loc)));
4023 -- Save the Tag in a local variable Tag_Tmp
4027 Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
4030 Make_Object_Declaration (Loc,
4031 Defining_Identifier => Tag_Tmp,
4032 Object_Definition => New_Reference_To (RTE (RE_Tag), Loc),
4034 Make_Selected_Component (Loc,
4035 Prefix => Duplicate_Subexpr_No_Checks (L),
4036 Selector_Name => New_Reference_To (First_Tag_Component (T),
4039 -- Otherwise Tag_Tmp not used
4046 if VM_Target /= No_VM then
4048 -- Cannot assign part of the object in a VM context, so instead
4049 -- fallback to the previous mechanism, even though it is not
4050 -- completely correct ???
4052 -- Save the Finalization Pointers in local variables Prev_Tmp and
4053 -- Next_Tmp. For objects with Has_Controlled_Component set, these
4054 -- pointers are in the Record_Controller
4056 Ctrl_Ref := Duplicate_Subexpr (L);
4058 if Has_Controlled_Component (T) then
4060 Make_Selected_Component (Loc,
4063 New_Reference_To (Controller_Component (T), Loc));
4067 Make_Defining_Identifier (Loc, New_Internal_Name ('B'));
4070 Make_Object_Declaration (Loc,
4071 Defining_Identifier => Prev_Tmp,
4073 Object_Definition =>
4074 New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
4077 Make_Selected_Component (Loc,
4079 Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref),
4080 Selector_Name => Make_Identifier (Loc, Name_Prev))));
4083 Make_Defining_Identifier (Loc,
4084 Chars => New_Internal_Name ('C'));
4087 Make_Object_Declaration (Loc,
4088 Defining_Identifier => Next_Tmp,
4090 Object_Definition =>
4091 New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
4094 Make_Selected_Component (Loc,
4096 Unchecked_Convert_To (RTE (RE_Finalizable),
4097 New_Copy_Tree (Ctrl_Ref)),
4098 Selector_Name => Make_Identifier (Loc, Name_Next))));
4100 -- Do the Assignment
4102 Append_To (Res, Relocate_Node (N));
4105 -- Regular (non VM) processing for controlled types and types with
4106 -- controlled components
4108 -- Variables of such types contain pointers used to chain them in
4109 -- finalization lists, in addition to user data. These pointers
4110 -- are specific to each object of the type, not to the value being
4113 -- Thus they need to be left intact during the assignment. We
4114 -- achieve this by constructing a Storage_Array subtype, and by
4115 -- overlaying objects of this type on the source and target of the
4116 -- assignment. The assignment is then rewritten to assignments of
4117 -- slices of these arrays, copying the user data, and leaving the
4118 -- pointers untouched.
4120 Controlled_Actions : declare
4122 -- A reference to the Prev component of the record controller
4124 First_After_Root : Node_Id := Empty;
4125 -- Index of first byte to be copied (used to skip
4126 -- Root_Controlled in controlled objects).
4128 Last_Before_Hole : Node_Id := Empty;
4129 -- Index of last byte to be copied before outermost record
4132 Hole_Length : Node_Id := Empty;
4133 -- Length of record controller data (Prev and Next pointers)
4135 First_After_Hole : Node_Id := Empty;
4136 -- Index of first byte to be copied after outermost record
4139 Expr, Source_Size : Node_Id;
4140 Source_Actual_Subtype : Entity_Id;
4141 -- Used for computation of the size of the data to be copied
4143 Range_Type : Entity_Id;
4144 Opaque_Type : Entity_Id;
4146 function Build_Slice
4149 Hi : Node_Id) return Node_Id;
4150 -- Build and return a slice of an array of type S overlaid on
4151 -- object Rec, with bounds specified by Lo and Hi. If either
4152 -- bound is empty, a default of S'First (respectively S'Last)
4159 function Build_Slice
4162 Hi : Node_Id) return Node_Id
4167 Opaque : constant Node_Id :=
4168 Unchecked_Convert_To (Opaque_Type,
4169 Make_Attribute_Reference (Loc,
4171 Attribute_Name => Name_Address));
4172 -- Access value designating an opaque storage array of type
4173 -- S overlaid on record Rec.
4176 -- Compute slice bounds using S'First (1) and S'Last as
4177 -- default values when not specified by the caller.
4180 Lo_Bound := Make_Integer_Literal (Loc, 1);
4186 Hi_Bound := Make_Attribute_Reference (Loc,
4187 Prefix => New_Occurrence_Of (Range_Type, Loc),
4188 Attribute_Name => Name_Last);
4193 return Make_Slice (Loc,
4196 Discrete_Range => Make_Range (Loc,
4197 Lo_Bound, Hi_Bound));
4200 -- Start of processing for Controlled_Actions
4203 -- Create a constrained subtype of Storage_Array whose size
4204 -- corresponds to the value being assigned.
4206 -- subtype G is Storage_Offset range
4207 -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit
4209 Expr := Duplicate_Subexpr_No_Checks (Expression (N));
4211 if Nkind (Expr) = N_Qualified_Expression then
4212 Expr := Expression (Expr);
4215 Source_Actual_Subtype := Etype (Expr);
4217 if Has_Discriminants (Source_Actual_Subtype)
4218 and then not Is_Constrained (Source_Actual_Subtype)
4221 Build_Actual_Subtype (Source_Actual_Subtype, Expr));
4222 Source_Actual_Subtype := Defining_Identifier (Last (Res));
4228 Make_Attribute_Reference (Loc,
4230 New_Occurrence_Of (Source_Actual_Subtype, Loc),
4231 Attribute_Name => Name_Size),
4233 Make_Integer_Literal (Loc,
4234 Intval => System_Storage_Unit - 1));
4237 Make_Op_Divide (Loc,
4238 Left_Opnd => Source_Size,
4240 Make_Integer_Literal (Loc,
4241 Intval => System_Storage_Unit));
4244 Make_Defining_Identifier (Loc,
4245 New_Internal_Name ('G'));
4248 Make_Subtype_Declaration (Loc,
4249 Defining_Identifier => Range_Type,
4250 Subtype_Indication =>
4251 Make_Subtype_Indication (Loc,
4253 New_Reference_To (RTE (RE_Storage_Offset), Loc),
4254 Constraint => Make_Range_Constraint (Loc,
4257 Low_Bound => Make_Integer_Literal (Loc, 1),
4258 High_Bound => Source_Size)))));
4260 -- subtype S is Storage_Array (G)
4263 Make_Subtype_Declaration (Loc,
4264 Defining_Identifier =>
4265 Make_Defining_Identifier (Loc,
4266 New_Internal_Name ('S')),
4267 Subtype_Indication =>
4268 Make_Subtype_Indication (Loc,
4270 New_Reference_To (RTE (RE_Storage_Array), Loc),
4272 Make_Index_Or_Discriminant_Constraint (Loc,
4274 New_List (New_Reference_To (Range_Type, Loc))))));
4276 -- type A is access S
4279 Make_Defining_Identifier (Loc,
4280 Chars => New_Internal_Name ('A'));
4283 Make_Full_Type_Declaration (Loc,
4284 Defining_Identifier => Opaque_Type,
4286 Make_Access_To_Object_Definition (Loc,
4287 Subtype_Indication =>
4289 Defining_Identifier (Last (Res)), Loc))));
4291 -- Generate appropriate slice assignments
4293 First_After_Root := Make_Integer_Literal (Loc, 1);
4295 -- For the case of a controlled object, skip the
4296 -- Root_Controlled part.
4298 if Is_Controlled (T) then
4302 Make_Op_Divide (Loc,
4303 Make_Attribute_Reference (Loc,
4305 New_Occurrence_Of (RTE (RE_Root_Controlled), Loc),
4306 Attribute_Name => Name_Size),
4307 Make_Integer_Literal (Loc, System_Storage_Unit)));
4310 -- For the case of a record with controlled components, skip
4311 -- the Prev and Next components of the record controller.
4312 -- These components constitute a 'hole' in the middle of the
4313 -- data to be copied.
4315 if Has_Controlled_Component (T) then
4317 Make_Selected_Component (Loc,
4319 Make_Selected_Component (Loc,
4320 Prefix => Duplicate_Subexpr_No_Checks (L),
4322 New_Reference_To (Controller_Component (T), Loc)),
4323 Selector_Name => Make_Identifier (Loc, Name_Prev));
4325 -- Last index before hole: determined by position of
4326 -- the _Controller.Prev component.
4329 Make_Defining_Identifier (Loc,
4330 New_Internal_Name ('L'));
4333 Make_Object_Declaration (Loc,
4334 Defining_Identifier => Last_Before_Hole,
4335 Object_Definition => New_Occurrence_Of (
4336 RTE (RE_Storage_Offset), Loc),
4337 Constant_Present => True,
4338 Expression => Make_Op_Add (Loc,
4339 Make_Attribute_Reference (Loc,
4341 Attribute_Name => Name_Position),
4342 Make_Attribute_Reference (Loc,
4343 Prefix => New_Copy_Tree (Prefix (Prev_Ref)),
4344 Attribute_Name => Name_Position))));
4346 -- Hole length: size of the Prev and Next components
4349 Make_Op_Multiply (Loc,
4350 Left_Opnd => Make_Integer_Literal (Loc, Uint_2),
4352 Make_Op_Divide (Loc,
4354 Make_Attribute_Reference (Loc,
4355 Prefix => New_Copy_Tree (Prev_Ref),
4356 Attribute_Name => Name_Size),
4358 Make_Integer_Literal (Loc,
4359 Intval => System_Storage_Unit)));
4361 -- First index after hole
4364 Make_Defining_Identifier (Loc,
4365 New_Internal_Name ('F'));
4368 Make_Object_Declaration (Loc,
4369 Defining_Identifier => First_After_Hole,
4370 Object_Definition => New_Occurrence_Of (
4371 RTE (RE_Storage_Offset), Loc),
4372 Constant_Present => True,
4378 New_Occurrence_Of (Last_Before_Hole, Loc),
4379 Right_Opnd => Hole_Length),
4380 Right_Opnd => Make_Integer_Literal (Loc, 1))));
4383 New_Occurrence_Of (Last_Before_Hole, Loc);
4385 New_Occurrence_Of (First_After_Hole, Loc);
4388 -- Assign the first slice (possibly skipping Root_Controlled,
4389 -- up to the beginning of the record controller if present,
4390 -- up to the end of the object if not).
4392 Append_To (Res, Make_Assignment_Statement (Loc,
4393 Name => Build_Slice (
4394 Rec => Duplicate_Subexpr_No_Checks (L),
4395 Lo => First_After_Root,
4396 Hi => Last_Before_Hole),
4398 Expression => Build_Slice (
4399 Rec => Expression (N),
4400 Lo => First_After_Root,
4401 Hi => New_Copy_Tree (Last_Before_Hole))));
4403 if Present (First_After_Hole) then
4405 -- If a record controller is present, copy the second slice,
4406 -- from right after the _Controller.Next component up to the
4407 -- end of the object.
4409 Append_To (Res, Make_Assignment_Statement (Loc,
4410 Name => Build_Slice (
4411 Rec => Duplicate_Subexpr_No_Checks (L),
4412 Lo => First_After_Hole,
4414 Expression => Build_Slice (
4415 Rec => Duplicate_Subexpr_No_Checks (Expression (N)),
4416 Lo => New_Copy_Tree (First_After_Hole),
4419 end Controlled_Actions;
4423 Append_To (Res, Relocate_Node (N));
4430 Make_Assignment_Statement (Loc,
4432 Make_Selected_Component (Loc,
4433 Prefix => Duplicate_Subexpr_No_Checks (L),
4434 Selector_Name => New_Reference_To (First_Tag_Component (T),
4436 Expression => New_Reference_To (Tag_Tmp, Loc)));
4440 if VM_Target /= No_VM then
4441 -- Restore the finalization pointers
4444 Make_Assignment_Statement (Loc,
4446 Make_Selected_Component (Loc,
4448 Unchecked_Convert_To (RTE (RE_Finalizable),
4449 New_Copy_Tree (Ctrl_Ref)),
4450 Selector_Name => Make_Identifier (Loc, Name_Prev)),
4451 Expression => New_Reference_To (Prev_Tmp, Loc)));
4454 Make_Assignment_Statement (Loc,
4456 Make_Selected_Component (Loc,
4458 Unchecked_Convert_To (RTE (RE_Finalizable),
4459 New_Copy_Tree (Ctrl_Ref)),
4460 Selector_Name => Make_Identifier (Loc, Name_Next)),
4461 Expression => New_Reference_To (Next_Tmp, Loc)));
4464 -- Adjust the target after the assignment when controlled (not in the
4465 -- init proc since it is an initialization more than an assignment).
4467 Append_List_To (Res,
4469 Ref => Duplicate_Subexpr_Move_Checks (L),
4471 Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc),
4472 With_Attach => Make_Integer_Literal (Loc, 0)));
4478 -- Could use comment here ???
4480 when RE_Not_Available =>
4482 end Make_Tag_Ctrl_Assignment;