1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2008, 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. In the case where we are returning
113 -- from a function body this is called by Expand_N_Simple_Return_Statement.
115 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
116 -- Generate the necessary code for controlled and tagged assignment,
117 -- that is to say, finalization of the target before, adjustment of
118 -- the target after and save and restore of the tag and finalization
119 -- pointers which are not 'part of the value' and must not be changed
120 -- upon assignment. N is the original Assignment node.
122 ------------------------------
123 -- Change_Of_Representation --
124 ------------------------------
126 function Change_Of_Representation (N : Node_Id) return Boolean is
127 Rhs : constant Node_Id := Expression (N);
130 Nkind (Rhs) = N_Type_Conversion
132 not Same_Representation (Etype (Rhs), Etype (Expression (Rhs)));
133 end Change_Of_Representation;
135 -------------------------
136 -- Expand_Assign_Array --
137 -------------------------
139 -- There are two issues here. First, do we let Gigi do a block move, or
140 -- do we expand out into a loop? Second, we need to set the two flags
141 -- Forwards_OK and Backwards_OK which show whether the block move (or
142 -- corresponding loops) can be legitimately done in a forwards (low to
143 -- high) or backwards (high to low) manner.
145 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is
146 Loc : constant Source_Ptr := Sloc (N);
148 Lhs : constant Node_Id := Name (N);
150 Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs);
151 Act_Rhs : Node_Id := Get_Referenced_Object (Rhs);
153 L_Type : constant Entity_Id :=
154 Underlying_Type (Get_Actual_Subtype (Act_Lhs));
155 R_Type : Entity_Id :=
156 Underlying_Type (Get_Actual_Subtype (Act_Rhs));
158 L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice;
159 R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice;
161 Crep : constant Boolean := Change_Of_Representation (N);
166 Ndim : constant Pos := Number_Dimensions (L_Type);
168 Loop_Required : Boolean := False;
169 -- This switch is set to True if the array move must be done using
170 -- an explicit front end generated loop.
172 procedure Apply_Dereference (Arg : Node_Id);
173 -- If the argument is an access to an array, and the assignment is
174 -- converted into a procedure call, apply explicit dereference.
176 function Has_Address_Clause (Exp : Node_Id) return Boolean;
177 -- Test if Exp is a reference to an array whose declaration has
178 -- an address clause, or it is a slice of such an array.
180 function Is_Formal_Array (Exp : Node_Id) return Boolean;
181 -- Test if Exp is a reference to an array which is either a formal
182 -- parameter or a slice of a formal parameter. These are the cases
183 -- where hidden aliasing can occur.
185 function Is_Non_Local_Array (Exp : Node_Id) return Boolean;
186 -- Determine if Exp is a reference to an array variable which is other
187 -- than an object defined in the current scope, or a slice of such
188 -- an object. Such objects can be aliased to parameters (unlike local
189 -- array references).
191 -----------------------
192 -- Apply_Dereference --
193 -----------------------
195 procedure Apply_Dereference (Arg : Node_Id) is
196 Typ : constant Entity_Id := Etype (Arg);
198 if Is_Access_Type (Typ) then
199 Rewrite (Arg, Make_Explicit_Dereference (Loc,
200 Prefix => Relocate_Node (Arg)));
201 Analyze_And_Resolve (Arg, Designated_Type (Typ));
203 end Apply_Dereference;
205 ------------------------
206 -- Has_Address_Clause --
207 ------------------------
209 function Has_Address_Clause (Exp : Node_Id) return Boolean is
212 (Is_Entity_Name (Exp) and then
213 Present (Address_Clause (Entity (Exp))))
215 (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp)));
216 end Has_Address_Clause;
218 ---------------------
219 -- Is_Formal_Array --
220 ---------------------
222 function Is_Formal_Array (Exp : Node_Id) return Boolean is
225 (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp)))
227 (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp)));
230 ------------------------
231 -- Is_Non_Local_Array --
232 ------------------------
234 function Is_Non_Local_Array (Exp : Node_Id) return Boolean is
236 return (Is_Entity_Name (Exp)
237 and then Scope (Entity (Exp)) /= Current_Scope)
238 or else (Nkind (Exp) = N_Slice
239 and then Is_Non_Local_Array (Prefix (Exp)));
240 end Is_Non_Local_Array;
242 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
244 Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs);
245 Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs);
247 Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs);
248 Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs);
250 -- Start of processing for Expand_Assign_Array
253 -- Deal with length check. Note that the length check is done with
254 -- respect to the right hand side as given, not a possible underlying
255 -- renamed object, since this would generate incorrect extra checks.
257 Apply_Length_Check (Rhs, L_Type);
259 -- We start by assuming that the move can be done in either direction,
260 -- i.e. that the two sides are completely disjoint.
262 Set_Forwards_OK (N, True);
263 Set_Backwards_OK (N, True);
265 -- Normally it is only the slice case that can lead to overlap, and
266 -- explicit checks for slices are made below. But there is one case
267 -- where the slice can be implicit and invisible to us: when we have a
268 -- one dimensional array, and either both operands are parameters, or
269 -- one is a parameter (which can be a slice passed by reference) and the
270 -- other is a non-local variable. In this case the parameter could be a
271 -- slice that overlaps with the other operand.
273 -- However, if the array subtype is a constrained first subtype in the
274 -- parameter case, then we don't have to worry about overlap, since
275 -- slice assignments aren't possible (other than for a slice denoting
278 -- Note: No overlap is possible if there is a change of representation,
279 -- so we can exclude this case.
284 ((Lhs_Formal and Rhs_Formal)
286 (Lhs_Formal and Rhs_Non_Local_Var)
288 (Rhs_Formal and Lhs_Non_Local_Var))
290 (not Is_Constrained (Etype (Lhs))
291 or else not Is_First_Subtype (Etype (Lhs)))
293 -- In the case of compiling for the Java or .NET Virtual Machine,
294 -- slices are always passed by making a copy, so we don't have to
295 -- worry about overlap. We also want to prevent generation of "<"
296 -- comparisons for array addresses, since that's a meaningless
297 -- operation on the VM.
299 and then VM_Target = No_VM
301 Set_Forwards_OK (N, False);
302 Set_Backwards_OK (N, False);
304 -- Note: the bit-packed case is not worrisome here, since if we have
305 -- a slice passed as a parameter, it is always aligned on a byte
306 -- boundary, and if there are no explicit slices, the assignment
307 -- can be performed directly.
310 -- We certainly must use a loop for change of representation and also
311 -- we use the operand of the conversion on the right hand side as the
312 -- effective right hand side (the component types must match in this
316 Act_Rhs := Get_Referenced_Object (Rhs);
317 R_Type := Get_Actual_Subtype (Act_Rhs);
318 Loop_Required := True;
320 -- We require a loop if the left side is possibly bit unaligned
322 elsif Possible_Bit_Aligned_Component (Lhs)
324 Possible_Bit_Aligned_Component (Rhs)
326 Loop_Required := True;
328 -- Arrays with controlled components are expanded into a loop to force
329 -- calls to Adjust at the component level.
331 elsif Has_Controlled_Component (L_Type) then
332 Loop_Required := True;
334 -- If object is atomic, we cannot tolerate a loop
336 elsif Is_Atomic_Object (Act_Lhs)
338 Is_Atomic_Object (Act_Rhs)
342 -- Loop is required if we have atomic components since we have to
343 -- be sure to do any accesses on an element by element basis.
345 elsif Has_Atomic_Components (L_Type)
346 or else Has_Atomic_Components (R_Type)
347 or else Is_Atomic (Component_Type (L_Type))
348 or else Is_Atomic (Component_Type (R_Type))
350 Loop_Required := True;
352 -- Case where no slice is involved
354 elsif not L_Slice and not R_Slice then
356 -- The following code deals with the case of unconstrained bit packed
357 -- arrays. The problem is that the template for such arrays contains
358 -- the bounds of the actual source level array, but the copy of an
359 -- entire array requires the bounds of the underlying array. It would
360 -- be nice if the back end could take care of this, but right now it
361 -- does not know how, so if we have such a type, then we expand out
362 -- into a loop, which is inefficient but works correctly. If we don't
363 -- do this, we get the wrong length computed for the array to be
364 -- moved. The two cases we need to worry about are:
366 -- Explicit deference of an unconstrained packed array type as in the
367 -- following example:
370 -- type BITS is array(INTEGER range <>) of BOOLEAN;
371 -- pragma PACK(BITS);
372 -- type A is access BITS;
375 -- P1 := new BITS (1 .. 65_535);
376 -- P2 := new BITS (1 .. 65_535);
380 -- A formal parameter reference with an unconstrained bit array type
381 -- is the other case we need to worry about (here we assume the same
382 -- BITS type declared above):
384 -- procedure Write_All (File : out BITS; Contents : BITS);
386 -- File.Storage := Contents;
389 -- We expand to a loop in either of these two cases
391 -- Question for future thought. Another potentially more efficient
392 -- approach would be to create the actual subtype, and then do an
393 -- unchecked conversion to this actual subtype ???
395 Check_Unconstrained_Bit_Packed_Array : declare
397 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean;
398 -- Function to perform required test for the first case, above
399 -- (dereference of an unconstrained bit packed array).
401 -----------------------
402 -- Is_UBPA_Reference --
403 -----------------------
405 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is
406 Typ : constant Entity_Id := Underlying_Type (Etype (Opnd));
408 Des_Type : Entity_Id;
411 if Present (Packed_Array_Type (Typ))
412 and then Is_Array_Type (Packed_Array_Type (Typ))
413 and then not Is_Constrained (Packed_Array_Type (Typ))
417 elsif Nkind (Opnd) = N_Explicit_Dereference then
418 P_Type := Underlying_Type (Etype (Prefix (Opnd)));
420 if not Is_Access_Type (P_Type) then
424 Des_Type := Designated_Type (P_Type);
426 Is_Bit_Packed_Array (Des_Type)
427 and then not Is_Constrained (Des_Type);
433 end Is_UBPA_Reference;
435 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
438 if Is_UBPA_Reference (Lhs)
440 Is_UBPA_Reference (Rhs)
442 Loop_Required := True;
444 -- Here if we do not have the case of a reference to a bit packed
445 -- unconstrained array case. In this case gigi can most certainly
446 -- handle the assignment if a forwards move is allowed.
448 -- (could it handle the backwards case also???)
450 elsif Forwards_OK (N) then
453 end Check_Unconstrained_Bit_Packed_Array;
455 -- The back end can always handle the assignment if the right side is a
456 -- string literal (note that overlap is definitely impossible in this
457 -- case). If the type is packed, a string literal is always converted
458 -- into an aggregate, except in the case of a null slice, for which no
459 -- aggregate can be written. In that case, rewrite the assignment as a
460 -- null statement, a length check has already been emitted to verify
461 -- that the range of the left-hand side is empty.
463 -- Note that this code is not executed if we have an assignment of a
464 -- string literal to a non-bit aligned component of a record, a case
465 -- which cannot be handled by the backend.
467 elsif Nkind (Rhs) = N_String_Literal then
468 if String_Length (Strval (Rhs)) = 0
469 and then Is_Bit_Packed_Array (L_Type)
471 Rewrite (N, Make_Null_Statement (Loc));
477 -- If either operand is bit packed, then we need a loop, since we can't
478 -- be sure that the slice is byte aligned. Similarly, if either operand
479 -- is a possibly unaligned slice, then we need a loop (since the back
480 -- end cannot handle unaligned slices).
482 elsif Is_Bit_Packed_Array (L_Type)
483 or else Is_Bit_Packed_Array (R_Type)
484 or else Is_Possibly_Unaligned_Slice (Lhs)
485 or else Is_Possibly_Unaligned_Slice (Rhs)
487 Loop_Required := True;
489 -- If we are not bit-packed, and we have only one slice, then no overlap
490 -- is possible except in the parameter case, so we can let the back end
493 elsif not (L_Slice and R_Slice) then
494 if Forwards_OK (N) then
499 -- If the right-hand side is a string literal, introduce a temporary for
500 -- it, for use in the generated loop that will follow.
502 if Nkind (Rhs) = N_String_Literal then
504 Temp : constant Entity_Id :=
505 Make_Defining_Identifier (Loc, New_Internal_Name ('T'));
510 Make_Object_Declaration (Loc,
511 Defining_Identifier => Temp,
512 Object_Definition => New_Occurrence_Of (L_Type, Loc),
513 Expression => Relocate_Node (Rhs));
515 Insert_Action (N, Decl);
516 Rewrite (Rhs, New_Occurrence_Of (Temp, Loc));
517 R_Type := Etype (Temp);
521 -- Come here to complete the analysis
523 -- Loop_Required: Set to True if we know that a loop is required
524 -- regardless of overlap considerations.
526 -- Forwards_OK: Set to False if we already know that a forwards
527 -- move is not safe, else set to True.
529 -- Backwards_OK: Set to False if we already know that a backwards
530 -- move is not safe, else set to True
532 -- Our task at this stage is to complete the overlap analysis, which can
533 -- result in possibly setting Forwards_OK or Backwards_OK to False, and
534 -- then generating the final code, either by deciding that it is OK
535 -- after all to let Gigi handle it, or by generating appropriate code
539 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
540 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type));
542 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ);
543 Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ);
544 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ);
545 Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ);
547 Act_L_Array : Node_Id;
548 Act_R_Array : Node_Id;
554 Cresult : Compare_Result;
557 -- Get the expressions for the arrays. If we are dealing with a
558 -- private type, then convert to the underlying type. We can do
559 -- direct assignments to an array that is a private type, but we
560 -- cannot assign to elements of the array without this extra
561 -- unchecked conversion.
563 if Nkind (Act_Lhs) = N_Slice then
564 Larray := Prefix (Act_Lhs);
568 if Is_Private_Type (Etype (Larray)) then
571 (Underlying_Type (Etype (Larray)), Larray);
575 if Nkind (Act_Rhs) = N_Slice then
576 Rarray := Prefix (Act_Rhs);
580 if Is_Private_Type (Etype (Rarray)) then
583 (Underlying_Type (Etype (Rarray)), Rarray);
587 -- If both sides are slices, we must figure out whether it is safe
588 -- to do the move in one direction or the other. It is always safe
589 -- if there is a change of representation since obviously two arrays
590 -- with different representations cannot possibly overlap.
592 if (not Crep) and L_Slice and R_Slice then
593 Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
594 Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
596 -- If both left and right hand arrays are entity names, and refer
597 -- to different entities, then we know that the move is safe (the
598 -- two storage areas are completely disjoint).
600 if Is_Entity_Name (Act_L_Array)
601 and then Is_Entity_Name (Act_R_Array)
602 and then Entity (Act_L_Array) /= Entity (Act_R_Array)
606 -- Otherwise, we assume the worst, which is that the two arrays
607 -- are the same array. There is no need to check if we know that
608 -- is the case, because if we don't know it, we still have to
611 -- Generally if the same array is involved, then we have an
612 -- overlapping case. We will have to really assume the worst (i.e.
613 -- set neither of the OK flags) unless we can determine the lower
614 -- or upper bounds at compile time and compare them.
617 Cresult := Compile_Time_Compare (Left_Lo, Right_Lo);
619 if Cresult = Unknown then
620 Cresult := Compile_Time_Compare (Left_Hi, Right_Hi);
624 when LT | LE | EQ => Set_Backwards_OK (N, False);
625 when GT | GE => Set_Forwards_OK (N, False);
626 when NE | Unknown => Set_Backwards_OK (N, False);
627 Set_Forwards_OK (N, False);
632 -- If after that analysis, Forwards_OK is still True, and
633 -- Loop_Required is False, meaning that we have not discovered some
634 -- non-overlap reason for requiring a loop, then we can still let
637 if not Loop_Required then
639 -- Assume gigi can handle it if Forwards_OK is set
641 if Forwards_OK (N) then
644 -- If Forwards_OK is not set, the back end will need something
645 -- like memmove to handle the move. For now, this processing is
646 -- activated using the .s debug flag (-gnatd.s).
648 elsif Debug_Flag_Dot_S then
653 -- At this stage we have to generate an explicit loop, and we have
654 -- the following cases:
656 -- Forwards_OK = True
658 -- Rnn : right_index := right_index'First;
659 -- for Lnn in left-index loop
660 -- left (Lnn) := right (Rnn);
661 -- Rnn := right_index'Succ (Rnn);
664 -- Note: the above code MUST be analyzed with checks off, because
665 -- otherwise the Succ could overflow. But in any case this is more
668 -- Forwards_OK = False, Backwards_OK = True
670 -- Rnn : right_index := right_index'Last;
671 -- for Lnn in reverse left-index loop
672 -- left (Lnn) := right (Rnn);
673 -- Rnn := right_index'Pred (Rnn);
676 -- Note: the above code MUST be analyzed with checks off, because
677 -- otherwise the Pred could overflow. But in any case this is more
680 -- Forwards_OK = Backwards_OK = False
682 -- This only happens if we have the same array on each side. It is
683 -- possible to create situations using overlays that violate this,
684 -- but we simply do not promise to get this "right" in this case.
686 -- There are two possible subcases. If the No_Implicit_Conditionals
687 -- restriction is set, then we generate the following code:
690 -- T : constant <operand-type> := rhs;
695 -- If implicit conditionals are permitted, then we generate:
697 -- if Left_Lo <= Right_Lo then
698 -- <code for Forwards_OK = True above>
700 -- <code for Backwards_OK = True above>
703 -- In order to detect possible aliasing, we examine the renamed
704 -- expression when the source or target is a renaming. However,
705 -- the renaming may be intended to capture an address that may be
706 -- affected by subsequent code, and therefore we must recover
707 -- the actual entity for the expansion that follows, not the
708 -- object it renames. In particular, if source or target designate
709 -- a portion of a dynamically allocated object, the pointer to it
710 -- may be reassigned but the renaming preserves the proper location.
712 if Is_Entity_Name (Rhs)
714 Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration
715 and then Nkind (Act_Rhs) = N_Slice
720 if Is_Entity_Name (Lhs)
722 Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration
723 and then Nkind (Act_Lhs) = N_Slice
728 -- Cases where either Forwards_OK or Backwards_OK is true
730 if Forwards_OK (N) or else Backwards_OK (N) then
731 if Controlled_Type (Component_Type (L_Type))
732 and then Base_Type (L_Type) = Base_Type (R_Type)
734 and then not No_Ctrl_Actions (N)
737 Proc : constant Entity_Id :=
738 TSS (Base_Type (L_Type), TSS_Slice_Assign);
742 Apply_Dereference (Larray);
743 Apply_Dereference (Rarray);
744 Actuals := New_List (
745 Duplicate_Subexpr (Larray, Name_Req => True),
746 Duplicate_Subexpr (Rarray, Name_Req => True),
747 Duplicate_Subexpr (Left_Lo, Name_Req => True),
748 Duplicate_Subexpr (Left_Hi, Name_Req => True),
749 Duplicate_Subexpr (Right_Lo, Name_Req => True),
750 Duplicate_Subexpr (Right_Hi, Name_Req => True));
754 Boolean_Literals (not Forwards_OK (N)), Loc));
757 Make_Procedure_Call_Statement (Loc,
758 Name => New_Reference_To (Proc, Loc),
759 Parameter_Associations => Actuals));
764 Expand_Assign_Array_Loop
765 (N, Larray, Rarray, L_Type, R_Type, Ndim,
766 Rev => not Forwards_OK (N)));
769 -- Case of both are false with No_Implicit_Conditionals
771 elsif Restriction_Active (No_Implicit_Conditionals) then
773 T : constant Entity_Id :=
774 Make_Defining_Identifier (Loc, Chars => Name_T);
778 Make_Block_Statement (Loc,
779 Declarations => New_List (
780 Make_Object_Declaration (Loc,
781 Defining_Identifier => T,
782 Constant_Present => True,
784 New_Occurrence_Of (Etype (Rhs), Loc),
785 Expression => Relocate_Node (Rhs))),
787 Handled_Statement_Sequence =>
788 Make_Handled_Sequence_Of_Statements (Loc,
789 Statements => New_List (
790 Make_Assignment_Statement (Loc,
791 Name => Relocate_Node (Lhs),
792 Expression => New_Occurrence_Of (T, Loc))))));
795 -- Case of both are false with implicit conditionals allowed
798 -- Before we generate this code, we must ensure that the left and
799 -- right side array types are defined. They may be itypes, and we
800 -- cannot let them be defined inside the if, since the first use
801 -- in the then may not be executed.
803 Ensure_Defined (L_Type, N);
804 Ensure_Defined (R_Type, N);
806 -- We normally compare addresses to find out which way round to
807 -- do the loop, since this is reliable, and handles the cases of
808 -- parameters, conversions etc. But we can't do that in the bit
809 -- packed case or the VM case, because addresses don't work there.
811 if not Is_Bit_Packed_Array (L_Type) and then VM_Target = No_VM then
815 Unchecked_Convert_To (RTE (RE_Integer_Address),
816 Make_Attribute_Reference (Loc,
818 Make_Indexed_Component (Loc,
820 Duplicate_Subexpr_Move_Checks (Larray, True),
821 Expressions => New_List (
822 Make_Attribute_Reference (Loc,
826 Attribute_Name => Name_First))),
827 Attribute_Name => Name_Address)),
830 Unchecked_Convert_To (RTE (RE_Integer_Address),
831 Make_Attribute_Reference (Loc,
833 Make_Indexed_Component (Loc,
835 Duplicate_Subexpr_Move_Checks (Rarray, True),
836 Expressions => New_List (
837 Make_Attribute_Reference (Loc,
841 Attribute_Name => Name_First))),
842 Attribute_Name => Name_Address)));
844 -- For the bit packed and VM cases we use the bounds. That's OK,
845 -- because we don't have to worry about parameters, since they
846 -- cannot cause overlap. Perhaps we should worry about weird slice
850 -- Copy the bounds and reset the Analyzed flag, because the
851 -- bounds of the index type itself may be universal, and must
852 -- must be reaanalyzed to acquire the proper type for Gigi.
854 Cleft_Lo := New_Copy_Tree (Left_Lo);
855 Cright_Lo := New_Copy_Tree (Right_Lo);
856 Set_Analyzed (Cleft_Lo, False);
857 Set_Analyzed (Cright_Lo, False);
861 Left_Opnd => Cleft_Lo,
862 Right_Opnd => Cright_Lo);
865 if Controlled_Type (Component_Type (L_Type))
866 and then Base_Type (L_Type) = Base_Type (R_Type)
868 and then not No_Ctrl_Actions (N)
871 -- Call TSS procedure for array assignment, passing the
872 -- explicit bounds of right and left hand sides.
875 Proc : constant Entity_Id :=
876 TSS (Base_Type (L_Type), TSS_Slice_Assign);
880 Apply_Dereference (Larray);
881 Apply_Dereference (Rarray);
882 Actuals := New_List (
883 Duplicate_Subexpr (Larray, Name_Req => True),
884 Duplicate_Subexpr (Rarray, Name_Req => True),
885 Duplicate_Subexpr (Left_Lo, Name_Req => True),
886 Duplicate_Subexpr (Left_Hi, Name_Req => True),
887 Duplicate_Subexpr (Right_Lo, Name_Req => True),
888 Duplicate_Subexpr (Right_Hi, Name_Req => True));
892 Right_Opnd => Condition));
895 Make_Procedure_Call_Statement (Loc,
896 Name => New_Reference_To (Proc, Loc),
897 Parameter_Associations => Actuals));
902 Make_Implicit_If_Statement (N,
903 Condition => Condition,
905 Then_Statements => New_List (
906 Expand_Assign_Array_Loop
907 (N, Larray, Rarray, L_Type, R_Type, Ndim,
910 Else_Statements => New_List (
911 Expand_Assign_Array_Loop
912 (N, Larray, Rarray, L_Type, R_Type, Ndim,
917 Analyze (N, Suppress => All_Checks);
921 when RE_Not_Available =>
923 end Expand_Assign_Array;
925 ------------------------------
926 -- Expand_Assign_Array_Loop --
927 ------------------------------
929 -- The following is an example of the loop generated for the case of a
930 -- two-dimensional array:
935 -- for L1b in 1 .. 100 loop
939 -- for L3b in 1 .. 100 loop
940 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
941 -- R4b := Tm1X2'succ(R4b);
944 -- R2b := Tm1X1'succ(R2b);
948 -- Here Rev is False, and Tm1Xn are the subscript types for the right hand
949 -- side. The declarations of R2b and R4b are inserted before the original
950 -- assignment statement.
952 function Expand_Assign_Array_Loop
959 Rev : Boolean) return Node_Id
961 Loc : constant Source_Ptr := Sloc (N);
963 Lnn : array (1 .. Ndim) of Entity_Id;
964 Rnn : array (1 .. Ndim) of Entity_Id;
965 -- Entities used as subscripts on left and right sides
967 L_Index_Type : array (1 .. Ndim) of Entity_Id;
968 R_Index_Type : array (1 .. Ndim) of Entity_Id;
969 -- Left and right index types
981 F_Or_L := Name_First;
985 -- Setup index types and subscript entities
992 L_Index := First_Index (L_Type);
993 R_Index := First_Index (R_Type);
995 for J in 1 .. Ndim loop
997 Make_Defining_Identifier (Loc,
998 Chars => New_Internal_Name ('L'));
1001 Make_Defining_Identifier (Loc,
1002 Chars => New_Internal_Name ('R'));
1004 L_Index_Type (J) := Etype (L_Index);
1005 R_Index_Type (J) := Etype (R_Index);
1007 Next_Index (L_Index);
1008 Next_Index (R_Index);
1012 -- Now construct the assignment statement
1015 ExprL : constant List_Id := New_List;
1016 ExprR : constant List_Id := New_List;
1019 for J in 1 .. Ndim loop
1020 Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc));
1021 Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc));
1025 Make_Assignment_Statement (Loc,
1027 Make_Indexed_Component (Loc,
1028 Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
1029 Expressions => ExprL),
1031 Make_Indexed_Component (Loc,
1032 Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
1033 Expressions => ExprR));
1035 -- We set assignment OK, since there are some cases, e.g. in object
1036 -- declarations, where we are actually assigning into a constant.
1037 -- If there really is an illegality, it was caught long before now,
1038 -- and was flagged when the original assignment was analyzed.
1040 Set_Assignment_OK (Name (Assign));
1042 -- Propagate the No_Ctrl_Actions flag to individual assignments
1044 Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
1047 -- Now construct the loop from the inside out, with the last subscript
1048 -- varying most rapidly. Note that Assign is first the raw assignment
1049 -- statement, and then subsequently the loop that wraps it up.
1051 for J in reverse 1 .. Ndim loop
1053 Make_Block_Statement (Loc,
1054 Declarations => New_List (
1055 Make_Object_Declaration (Loc,
1056 Defining_Identifier => Rnn (J),
1057 Object_Definition =>
1058 New_Occurrence_Of (R_Index_Type (J), Loc),
1060 Make_Attribute_Reference (Loc,
1061 Prefix => New_Occurrence_Of (R_Index_Type (J), Loc),
1062 Attribute_Name => F_Or_L))),
1064 Handled_Statement_Sequence =>
1065 Make_Handled_Sequence_Of_Statements (Loc,
1066 Statements => New_List (
1067 Make_Implicit_Loop_Statement (N,
1069 Make_Iteration_Scheme (Loc,
1070 Loop_Parameter_Specification =>
1071 Make_Loop_Parameter_Specification (Loc,
1072 Defining_Identifier => Lnn (J),
1073 Reverse_Present => Rev,
1074 Discrete_Subtype_Definition =>
1075 New_Reference_To (L_Index_Type (J), Loc))),
1077 Statements => New_List (
1080 Make_Assignment_Statement (Loc,
1081 Name => New_Occurrence_Of (Rnn (J), Loc),
1083 Make_Attribute_Reference (Loc,
1085 New_Occurrence_Of (R_Index_Type (J), Loc),
1086 Attribute_Name => S_Or_P,
1087 Expressions => New_List (
1088 New_Occurrence_Of (Rnn (J), Loc)))))))));
1092 end Expand_Assign_Array_Loop;
1094 --------------------------
1095 -- Expand_Assign_Record --
1096 --------------------------
1098 -- The only processing required is in the change of representation case,
1099 -- where we must expand the assignment to a series of field by field
1102 procedure Expand_Assign_Record (N : Node_Id) is
1103 Lhs : constant Node_Id := Name (N);
1104 Rhs : Node_Id := Expression (N);
1107 -- If change of representation, then extract the real right hand side
1108 -- from the type conversion, and proceed with component-wise assignment,
1109 -- since the two types are not the same as far as the back end is
1112 if Change_Of_Representation (N) then
1113 Rhs := Expression (Rhs);
1115 -- If this may be a case of a large bit aligned component, then proceed
1116 -- with component-wise assignment, to avoid possible clobbering of other
1117 -- components sharing bits in the first or last byte of the component to
1120 elsif Possible_Bit_Aligned_Component (Lhs)
1122 Possible_Bit_Aligned_Component (Rhs)
1126 -- If neither condition met, then nothing special to do, the back end
1127 -- can handle assignment of the entire component as a single entity.
1133 -- At this stage we know that we must do a component wise assignment
1136 Loc : constant Source_Ptr := Sloc (N);
1137 R_Typ : constant Entity_Id := Base_Type (Etype (Rhs));
1138 L_Typ : constant Entity_Id := Base_Type (Etype (Lhs));
1139 Decl : constant Node_Id := Declaration_Node (R_Typ);
1143 function Find_Component
1145 Comp : Entity_Id) return Entity_Id;
1146 -- Find the component with the given name in the underlying record
1147 -- declaration for Typ. We need to use the actual entity because the
1148 -- type may be private and resolution by identifier alone would fail.
1150 function Make_Component_List_Assign
1152 U_U : Boolean := False) return List_Id;
1153 -- Returns a sequence of statements to assign the components that
1154 -- are referenced in the given component list. The flag U_U is
1155 -- used to force the usage of the inferred value of the variant
1156 -- part expression as the switch for the generated case statement.
1158 function Make_Field_Assign
1160 U_U : Boolean := False) return Node_Id;
1161 -- Given C, the entity for a discriminant or component, build an
1162 -- assignment for the corresponding field values. The flag U_U
1163 -- signals the presence of an Unchecked_Union and forces the usage
1164 -- of the inferred discriminant value of C as the right hand side
1165 -- of the assignment.
1167 function Make_Field_Assigns (CI : List_Id) return List_Id;
1168 -- Given CI, a component items list, construct series of statements
1169 -- for fieldwise assignment of the corresponding components.
1171 --------------------
1172 -- Find_Component --
1173 --------------------
1175 function Find_Component
1177 Comp : Entity_Id) return Entity_Id
1179 Utyp : constant Entity_Id := Underlying_Type (Typ);
1183 C := First_Entity (Utyp);
1185 while Present (C) loop
1186 if Chars (C) = Chars (Comp) then
1192 raise Program_Error;
1195 --------------------------------
1196 -- Make_Component_List_Assign --
1197 --------------------------------
1199 function Make_Component_List_Assign
1201 U_U : Boolean := False) return List_Id
1203 CI : constant List_Id := Component_Items (CL);
1204 VP : constant Node_Id := Variant_Part (CL);
1214 Result := Make_Field_Assigns (CI);
1216 if Present (VP) then
1218 V := First_Non_Pragma (Variants (VP));
1220 while Present (V) loop
1223 DC := First (Discrete_Choices (V));
1224 while Present (DC) loop
1225 Append_To (DCH, New_Copy_Tree (DC));
1230 Make_Case_Statement_Alternative (Loc,
1231 Discrete_Choices => DCH,
1233 Make_Component_List_Assign (Component_List (V))));
1234 Next_Non_Pragma (V);
1237 -- If we have an Unchecked_Union, use the value of the inferred
1238 -- discriminant of the variant part expression as the switch
1239 -- for the case statement. The case statement may later be
1244 New_Copy (Get_Discriminant_Value (
1247 Discriminant_Constraint (Etype (Rhs))));
1250 Make_Selected_Component (Loc,
1251 Prefix => Duplicate_Subexpr (Rhs),
1253 Make_Identifier (Loc, Chars (Name (VP))));
1257 Make_Case_Statement (Loc,
1259 Alternatives => Alts));
1263 end Make_Component_List_Assign;
1265 -----------------------
1266 -- Make_Field_Assign --
1267 -----------------------
1269 function Make_Field_Assign
1271 U_U : Boolean := False) return Node_Id
1277 -- In the case of an Unchecked_Union, use the discriminant
1278 -- constraint value as on the right hand side of the assignment.
1282 New_Copy (Get_Discriminant_Value (C,
1284 Discriminant_Constraint (Etype (Rhs))));
1287 Make_Selected_Component (Loc,
1288 Prefix => Duplicate_Subexpr (Rhs),
1289 Selector_Name => New_Occurrence_Of (C, Loc));
1293 Make_Assignment_Statement (Loc,
1295 Make_Selected_Component (Loc,
1296 Prefix => Duplicate_Subexpr (Lhs),
1298 New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
1299 Expression => Expr);
1301 -- Set Assignment_OK, so discriminants can be assigned
1303 Set_Assignment_OK (Name (A), True);
1305 end Make_Field_Assign;
1307 ------------------------
1308 -- Make_Field_Assigns --
1309 ------------------------
1311 function Make_Field_Assigns (CI : List_Id) return List_Id is
1318 while Present (Item) loop
1319 if Nkind (Item) = N_Component_Declaration then
1321 (Result, Make_Field_Assign (Defining_Identifier (Item)));
1328 end Make_Field_Assigns;
1330 -- Start of processing for Expand_Assign_Record
1333 -- Note that we use the base types for this processing. This results
1334 -- in some extra work in the constrained case, but the change of
1335 -- representation case is so unusual that it is not worth the effort.
1337 -- First copy the discriminants. This is done unconditionally. It
1338 -- is required in the unconstrained left side case, and also in the
1339 -- case where this assignment was constructed during the expansion
1340 -- of a type conversion (since initialization of discriminants is
1341 -- suppressed in this case). It is unnecessary but harmless in
1344 if Has_Discriminants (L_Typ) then
1345 F := First_Discriminant (R_Typ);
1346 while Present (F) loop
1348 -- If we are expanding the initialization of a derived record
1349 -- that constrains or renames discriminants of the parent, we
1350 -- must use the corresponding discriminant in the parent.
1357 and then Present (Corresponding_Discriminant (F))
1359 CF := Corresponding_Discriminant (F);
1364 if Is_Unchecked_Union (Base_Type (R_Typ)) then
1365 Insert_Action (N, Make_Field_Assign (CF, True));
1367 Insert_Action (N, Make_Field_Assign (CF));
1370 Next_Discriminant (F);
1375 -- We know the underlying type is a record, but its current view
1376 -- may be private. We must retrieve the usable record declaration.
1378 if Nkind (Decl) = N_Private_Type_Declaration
1379 and then Present (Full_View (R_Typ))
1381 RDef := Type_Definition (Declaration_Node (Full_View (R_Typ)));
1383 RDef := Type_Definition (Decl);
1386 if Nkind (RDef) = N_Record_Definition
1387 and then Present (Component_List (RDef))
1390 if Is_Unchecked_Union (R_Typ) then
1392 Make_Component_List_Assign (Component_List (RDef), True));
1395 (N, Make_Component_List_Assign (Component_List (RDef)));
1398 Rewrite (N, Make_Null_Statement (Loc));
1402 end Expand_Assign_Record;
1404 -----------------------------------
1405 -- Expand_N_Assignment_Statement --
1406 -----------------------------------
1408 -- This procedure implements various cases where an assignment statement
1409 -- cannot just be passed on to the back end in untransformed state.
1411 procedure Expand_N_Assignment_Statement (N : Node_Id) is
1412 Loc : constant Source_Ptr := Sloc (N);
1413 Lhs : constant Node_Id := Name (N);
1414 Rhs : constant Node_Id := Expression (N);
1415 Typ : constant Entity_Id := Underlying_Type (Etype (Lhs));
1419 -- Ada 2005 (AI-327): Handle assignment to priority of protected object
1421 -- Rewrite an assignment to X'Priority into a run-time call
1423 -- For example: X'Priority := New_Prio_Expr;
1424 -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr);
1426 -- Note that although X'Priority is notionally an object, it is quite
1427 -- deliberately not defined as an aliased object in the RM. This means
1428 -- that it works fine to rewrite it as a call, without having to worry
1429 -- about complications that would other arise from X'Priority'Access,
1430 -- which is illegal, because of the lack of aliasing.
1432 if Ada_Version >= Ada_05 then
1435 Conctyp : Entity_Id;
1438 RT_Subprg_Name : Node_Id;
1441 -- Handle chains of renamings
1444 while Nkind (Ent) in N_Has_Entity
1445 and then Present (Entity (Ent))
1446 and then Present (Renamed_Object (Entity (Ent)))
1448 Ent := Renamed_Object (Entity (Ent));
1451 -- The attribute Priority applied to protected objects has been
1452 -- previously expanded into a call to the Get_Ceiling run-time
1455 if Nkind (Ent) = N_Function_Call
1456 and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling)
1458 Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling))
1460 -- Look for the enclosing concurrent type
1462 Conctyp := Current_Scope;
1463 while not Is_Concurrent_Type (Conctyp) loop
1464 Conctyp := Scope (Conctyp);
1467 pragma Assert (Is_Protected_Type (Conctyp));
1469 -- Generate the first actual of the call
1471 Subprg := Current_Scope;
1472 while not Present (Protected_Body_Subprogram (Subprg)) loop
1473 Subprg := Scope (Subprg);
1476 -- Select the appropriate run-time call
1478 if Number_Entries (Conctyp) = 0 then
1480 New_Reference_To (RTE (RE_Set_Ceiling), Loc);
1483 New_Reference_To (RTE (RO_PE_Set_Ceiling), Loc);
1487 Make_Procedure_Call_Statement (Loc,
1488 Name => RT_Subprg_Name,
1489 Parameter_Associations => New_List (
1490 New_Copy_Tree (First (Parameter_Associations (Ent))),
1491 Relocate_Node (Expression (N))));
1500 -- First deal with generation of range check if required. For now we do
1501 -- this only for discrete types.
1503 if Do_Range_Check (Rhs)
1504 and then Is_Discrete_Type (Typ)
1506 Set_Do_Range_Check (Rhs, False);
1507 Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed);
1510 -- Check for a special case where a high level transformation is
1511 -- required. If we have either of:
1516 -- where P is a reference to a bit packed array, then we have to unwind
1517 -- the assignment. The exact meaning of being a reference to a bit
1518 -- packed array is as follows:
1520 -- An indexed component whose prefix is a bit packed array is a
1521 -- reference to a bit packed array.
1523 -- An indexed component or selected component whose prefix is a
1524 -- reference to a bit packed array is itself a reference ot a
1525 -- bit packed array.
1527 -- The required transformation is
1529 -- Tnn : prefix_type := P;
1530 -- Tnn.field := rhs;
1535 -- Tnn : prefix_type := P;
1536 -- Tnn (subscr) := rhs;
1539 -- Since P is going to be evaluated more than once, any subscripts
1540 -- in P must have their evaluation forced.
1542 if Nkind_In (Lhs, N_Indexed_Component, N_Selected_Component)
1543 and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs))
1546 BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs));
1547 BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr);
1548 Tnn : constant Entity_Id :=
1549 Make_Defining_Identifier (Loc,
1550 Chars => New_Internal_Name ('T'));
1553 -- Insert the post assignment first, because we want to copy the
1554 -- BPAR_Expr tree before it gets analyzed in the context of the
1555 -- pre assignment. Note that we do not analyze the post assignment
1556 -- yet (we cannot till we have completed the analysis of the pre
1557 -- assignment). As usual, the analysis of this post assignment
1558 -- will happen on its own when we "run into" it after finishing
1559 -- the current assignment.
1562 Make_Assignment_Statement (Loc,
1563 Name => New_Copy_Tree (BPAR_Expr),
1564 Expression => New_Occurrence_Of (Tnn, Loc)));
1566 -- At this stage BPAR_Expr is a reference to a bit packed array
1567 -- where the reference was not expanded in the original tree,
1568 -- since it was on the left side of an assignment. But in the
1569 -- pre-assignment statement (the object definition), BPAR_Expr
1570 -- will end up on the right hand side, and must be reexpanded. To
1571 -- achieve this, we reset the analyzed flag of all selected and
1572 -- indexed components down to the actual indexed component for
1573 -- the packed array.
1577 Set_Analyzed (Exp, False);
1580 (Exp, N_Selected_Component, N_Indexed_Component)
1582 Exp := Prefix (Exp);
1588 -- Now we can insert and analyze the pre-assignment
1590 -- If the right-hand side requires a transient scope, it has
1591 -- already been placed on the stack. However, the declaration is
1592 -- inserted in the tree outside of this scope, and must reflect
1593 -- the proper scope for its variable. This awkward bit is forced
1594 -- by the stricter scope discipline imposed by GCC 2.97.
1597 Uses_Transient_Scope : constant Boolean :=
1599 and then N = Node_To_Be_Wrapped;
1602 if Uses_Transient_Scope then
1603 Push_Scope (Scope (Current_Scope));
1606 Insert_Before_And_Analyze (N,
1607 Make_Object_Declaration (Loc,
1608 Defining_Identifier => Tnn,
1609 Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc),
1610 Expression => BPAR_Expr));
1612 if Uses_Transient_Scope then
1617 -- Now fix up the original assignment and continue processing
1619 Rewrite (Prefix (Lhs),
1620 New_Occurrence_Of (Tnn, Loc));
1622 -- We do not need to reanalyze that assignment, and we do not need
1623 -- to worry about references to the temporary, but we do need to
1624 -- make sure that the temporary is not marked as a true constant
1625 -- since we now have a generated assignment to it!
1627 Set_Is_True_Constant (Tnn, False);
1631 -- When we have the appropriate type of aggregate in the expression (it
1632 -- has been determined during analysis of the aggregate by setting the
1633 -- delay flag), let's perform in place assignment and thus avoid
1634 -- creating a temporary.
1636 if Is_Delayed_Aggregate (Rhs) then
1637 Convert_Aggr_In_Assignment (N);
1638 Rewrite (N, Make_Null_Statement (Loc));
1643 -- Apply discriminant check if required. If Lhs is an access type to a
1644 -- designated type with discriminants, we must always check.
1646 if Has_Discriminants (Etype (Lhs)) then
1648 -- Skip discriminant check if change of representation. Will be
1649 -- done when the change of representation is expanded out.
1651 if not Change_Of_Representation (N) then
1652 Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs);
1655 -- If the type is private without discriminants, and the full type
1656 -- has discriminants (necessarily with defaults) a check may still be
1657 -- necessary if the Lhs is aliased. The private determinants must be
1658 -- visible to build the discriminant constraints.
1660 -- Only an explicit dereference that comes from source indicates
1661 -- aliasing. Access to formals of protected operations and entries
1662 -- create dereferences but are not semantic aliasings.
1664 elsif Is_Private_Type (Etype (Lhs))
1665 and then Has_Discriminants (Typ)
1666 and then Nkind (Lhs) = N_Explicit_Dereference
1667 and then Comes_From_Source (Lhs)
1670 Lt : constant Entity_Id := Etype (Lhs);
1672 Set_Etype (Lhs, Typ);
1673 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1674 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1675 Set_Etype (Lhs, Lt);
1678 -- If the Lhs has a private type with unknown discriminants, it
1679 -- may have a full view with discriminants, but those are nameable
1680 -- only in the underlying type, so convert the Rhs to it before
1681 -- potential checking.
1683 elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs)))
1684 and then Has_Discriminants (Typ)
1686 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1687 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1689 -- In the access type case, we need the same discriminant check, and
1690 -- also range checks if we have an access to constrained array.
1692 elsif Is_Access_Type (Etype (Lhs))
1693 and then Is_Constrained (Designated_Type (Etype (Lhs)))
1695 if Has_Discriminants (Designated_Type (Etype (Lhs))) then
1697 -- Skip discriminant check if change of representation. Will be
1698 -- done when the change of representation is expanded out.
1700 if not Change_Of_Representation (N) then
1701 Apply_Discriminant_Check (Rhs, Etype (Lhs));
1704 elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then
1705 Apply_Range_Check (Rhs, Etype (Lhs));
1707 if Is_Constrained (Etype (Lhs)) then
1708 Apply_Length_Check (Rhs, Etype (Lhs));
1711 if Nkind (Rhs) = N_Allocator then
1713 Target_Typ : constant Entity_Id := Etype (Expression (Rhs));
1714 C_Es : Check_Result;
1721 Etype (Designated_Type (Etype (Lhs))));
1733 -- Apply range check for access type case
1735 elsif Is_Access_Type (Etype (Lhs))
1736 and then Nkind (Rhs) = N_Allocator
1737 and then Nkind (Expression (Rhs)) = N_Qualified_Expression
1739 Analyze_And_Resolve (Expression (Rhs));
1741 (Expression (Rhs), Designated_Type (Etype (Lhs)));
1744 -- Ada 2005 (AI-231): Generate the run-time check
1746 if Is_Access_Type (Typ)
1747 and then Can_Never_Be_Null (Etype (Lhs))
1748 and then not Can_Never_Be_Null (Etype (Rhs))
1750 Apply_Constraint_Check (Rhs, Etype (Lhs));
1753 -- Case of assignment to a bit packed array element
1755 if Nkind (Lhs) = N_Indexed_Component
1756 and then Is_Bit_Packed_Array (Etype (Prefix (Lhs)))
1758 Expand_Bit_Packed_Element_Set (N);
1761 -- Build-in-place function call case. Note that we're not yet doing
1762 -- build-in-place for user-written assignment statements (the assignment
1763 -- here came from an aggregate.)
1765 elsif Ada_Version >= Ada_05
1766 and then Is_Build_In_Place_Function_Call (Rhs)
1768 Make_Build_In_Place_Call_In_Assignment (N, Rhs);
1770 elsif Is_Tagged_Type (Typ) and then Is_Value_Type (Etype (Lhs)) then
1772 -- Nothing to do for valuetypes
1773 -- ??? Set_Scope_Is_Transient (False);
1777 elsif Is_Tagged_Type (Typ)
1778 or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ))
1780 Tagged_Case : declare
1781 L : List_Id := No_List;
1782 Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N);
1785 -- In the controlled case, we need to make sure that function
1786 -- calls are evaluated before finalizing the target. In all cases,
1787 -- it makes the expansion easier if the side-effects are removed
1790 Remove_Side_Effects (Lhs);
1791 Remove_Side_Effects (Rhs);
1793 -- Avoid recursion in the mechanism
1797 -- If dispatching assignment, we need to dispatch to _assign
1799 if Is_Class_Wide_Type (Typ)
1801 -- If the type is tagged, we may as well use the predefined
1802 -- primitive assignment. This avoids inlining a lot of code
1803 -- and in the class-wide case, the assignment is replaced by
1804 -- dispatch call to _assign. Note that this cannot be done when
1805 -- discriminant checks are locally suppressed (as in extension
1806 -- aggregate expansions) because otherwise the discriminant
1807 -- check will be performed within the _assign call. It is also
1808 -- suppressed for assignments created by the expander that
1809 -- correspond to initializations, where we do want to copy the
1810 -- tag (No_Ctrl_Actions flag set True) by the expander and we
1811 -- do not need to mess with tags ever (Expand_Ctrl_Actions flag
1812 -- is set True in this case).
1814 or else (Is_Tagged_Type (Typ)
1815 and then not Is_Value_Type (Etype (Lhs))
1816 and then Chars (Current_Scope) /= Name_uAssign
1817 and then Expand_Ctrl_Actions
1818 and then not Discriminant_Checks_Suppressed (Empty))
1820 -- Fetch the primitive op _assign and proper type to call it.
1821 -- Because of possible conflicts between private and full view
1822 -- the proper type is fetched directly from the operation
1826 Op : constant Entity_Id :=
1827 Find_Prim_Op (Typ, Name_uAssign);
1828 F_Typ : Entity_Id := Etype (First_Formal (Op));
1831 -- If the assignment is dispatching, make sure to use the
1834 if Is_Class_Wide_Type (Typ) then
1835 F_Typ := Class_Wide_Type (F_Typ);
1840 -- In case of assignment to a class-wide tagged type, before
1841 -- the assignment we generate run-time check to ensure that
1842 -- the tags of source and target match.
1844 if Is_Class_Wide_Type (Typ)
1845 and then Is_Tagged_Type (Typ)
1846 and then Is_Tagged_Type (Underlying_Type (Etype (Rhs)))
1849 Make_Raise_Constraint_Error (Loc,
1853 Make_Selected_Component (Loc,
1854 Prefix => Duplicate_Subexpr (Lhs),
1856 Make_Identifier (Loc,
1857 Chars => Name_uTag)),
1859 Make_Selected_Component (Loc,
1860 Prefix => Duplicate_Subexpr (Rhs),
1862 Make_Identifier (Loc,
1863 Chars => Name_uTag))),
1864 Reason => CE_Tag_Check_Failed));
1868 Make_Procedure_Call_Statement (Loc,
1869 Name => New_Reference_To (Op, Loc),
1870 Parameter_Associations => New_List (
1871 Unchecked_Convert_To (F_Typ,
1872 Duplicate_Subexpr (Lhs)),
1873 Unchecked_Convert_To (F_Typ,
1874 Duplicate_Subexpr (Rhs)))));
1878 L := Make_Tag_Ctrl_Assignment (N);
1880 -- We can't afford to have destructive Finalization Actions in
1881 -- the Self assignment case, so if the target and the source
1882 -- are not obviously different, code is generated to avoid the
1883 -- self assignment case:
1885 -- if lhs'address /= rhs'address then
1886 -- <code for controlled and/or tagged assignment>
1889 -- Skip this if Restriction (No_Finalization) is active
1891 if not Statically_Different (Lhs, Rhs)
1892 and then Expand_Ctrl_Actions
1893 and then not Restriction_Active (No_Finalization)
1896 Make_Implicit_If_Statement (N,
1900 Make_Attribute_Reference (Loc,
1901 Prefix => Duplicate_Subexpr (Lhs),
1902 Attribute_Name => Name_Address),
1905 Make_Attribute_Reference (Loc,
1906 Prefix => Duplicate_Subexpr (Rhs),
1907 Attribute_Name => Name_Address)),
1909 Then_Statements => L));
1912 -- We need to set up an exception handler for implementing
1913 -- 7.6.1(18). The remaining adjustments are tackled by the
1914 -- implementation of adjust for record_controllers (see
1917 -- This is skipped if we have no finalization
1919 if Expand_Ctrl_Actions
1920 and then not Restriction_Active (No_Finalization)
1923 Make_Block_Statement (Loc,
1924 Handled_Statement_Sequence =>
1925 Make_Handled_Sequence_Of_Statements (Loc,
1927 Exception_Handlers => New_List (
1928 Make_Handler_For_Ctrl_Operation (Loc)))));
1933 Make_Block_Statement (Loc,
1934 Handled_Statement_Sequence =>
1935 Make_Handled_Sequence_Of_Statements (Loc, Statements => L)));
1937 -- If no restrictions on aborts, protect the whole assignment
1938 -- for controlled objects as per 9.8(11).
1940 if Controlled_Type (Typ)
1941 and then Expand_Ctrl_Actions
1942 and then Abort_Allowed
1945 Blk : constant Entity_Id :=
1947 (E_Block, Current_Scope, Sloc (N), 'B');
1950 Set_Scope (Blk, Current_Scope);
1951 Set_Etype (Blk, Standard_Void_Type);
1952 Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N)));
1954 Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer));
1955 Set_At_End_Proc (Handled_Statement_Sequence (N),
1956 New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc));
1957 Expand_At_End_Handler
1958 (Handled_Statement_Sequence (N), Blk);
1962 -- N has been rewritten to a block statement for which it is
1963 -- known by construction that no checks are necessary: analyze
1964 -- it with all checks suppressed.
1966 Analyze (N, Suppress => All_Checks);
1972 elsif Is_Array_Type (Typ) then
1974 Actual_Rhs : Node_Id := Rhs;
1977 while Nkind_In (Actual_Rhs, N_Type_Conversion,
1978 N_Qualified_Expression)
1980 Actual_Rhs := Expression (Actual_Rhs);
1983 Expand_Assign_Array (N, Actual_Rhs);
1989 elsif Is_Record_Type (Typ) then
1990 Expand_Assign_Record (N);
1993 -- Scalar types. This is where we perform the processing related to the
1994 -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid
1997 elsif Is_Scalar_Type (Typ) then
1999 -- Case where right side is known valid
2001 if Expr_Known_Valid (Rhs) then
2003 -- Here the right side is valid, so it is fine. The case to deal
2004 -- with is when the left side is a local variable reference whose
2005 -- value is not currently known to be valid. If this is the case,
2006 -- and the assignment appears in an unconditional context, then we
2007 -- can mark the left side as now being valid.
2009 if Is_Local_Variable_Reference (Lhs)
2010 and then not Is_Known_Valid (Entity (Lhs))
2011 and then In_Unconditional_Context (N)
2013 Set_Is_Known_Valid (Entity (Lhs), True);
2016 -- Case where right side may be invalid in the sense of the RM
2017 -- reference above. The RM does not require that we check for the
2018 -- validity on an assignment, but it does require that the assignment
2019 -- of an invalid value not cause erroneous behavior.
2021 -- The general approach in GNAT is to use the Is_Known_Valid flag
2022 -- to avoid the need for validity checking on assignments. However
2023 -- in some cases, we have to do validity checking in order to make
2024 -- sure that the setting of this flag is correct.
2027 -- Validate right side if we are validating copies
2029 if Validity_Checks_On
2030 and then Validity_Check_Copies
2032 -- Skip this if left hand side is an array or record component
2033 -- and elementary component validity checks are suppressed.
2035 if Nkind_In (Lhs, N_Selected_Component, N_Indexed_Component)
2036 and then not Validity_Check_Components
2043 -- We can propagate this to the left side where appropriate
2045 if Is_Local_Variable_Reference (Lhs)
2046 and then not Is_Known_Valid (Entity (Lhs))
2047 and then In_Unconditional_Context (N)
2049 Set_Is_Known_Valid (Entity (Lhs), True);
2052 -- Otherwise check to see what should be done
2054 -- If left side is a local variable, then we just set its flag to
2055 -- indicate that its value may no longer be valid, since we are
2056 -- copying a potentially invalid value.
2058 elsif Is_Local_Variable_Reference (Lhs) then
2059 Set_Is_Known_Valid (Entity (Lhs), False);
2061 -- Check for case of a nonlocal variable on the left side which
2062 -- is currently known to be valid. In this case, we simply ensure
2063 -- that the right side is valid. We only play the game of copying
2064 -- validity status for local variables, since we are doing this
2065 -- statically, not by tracing the full flow graph.
2067 elsif Is_Entity_Name (Lhs)
2068 and then Is_Known_Valid (Entity (Lhs))
2070 -- Note: If Validity_Checking mode is set to none, we ignore
2071 -- the Ensure_Valid call so don't worry about that case here.
2075 -- In all other cases, we can safely copy an invalid value without
2076 -- worrying about the status of the left side. Since it is not a
2077 -- variable reference it will not be considered
2078 -- as being known to be valid in any case.
2086 -- Defend against invalid subscripts on left side if we are in standard
2087 -- validity checking mode. No need to do this if we are checking all
2090 if Validity_Checks_On
2091 and then Validity_Check_Default
2092 and then not Validity_Check_Subscripts
2094 Check_Valid_Lvalue_Subscripts (Lhs);
2098 when RE_Not_Available =>
2100 end Expand_N_Assignment_Statement;
2102 ------------------------------
2103 -- Expand_N_Block_Statement --
2104 ------------------------------
2106 -- Encode entity names defined in block statement
2108 procedure Expand_N_Block_Statement (N : Node_Id) is
2110 Qualify_Entity_Names (N);
2111 end Expand_N_Block_Statement;
2113 -----------------------------
2114 -- Expand_N_Case_Statement --
2115 -----------------------------
2117 procedure Expand_N_Case_Statement (N : Node_Id) is
2118 Loc : constant Source_Ptr := Sloc (N);
2119 Expr : constant Node_Id := Expression (N);
2127 -- Check for the situation where we know at compile time which branch
2130 if Compile_Time_Known_Value (Expr) then
2131 Alt := Find_Static_Alternative (N);
2133 -- Move statements from this alternative after the case statement.
2134 -- They are already analyzed, so will be skipped by the analyzer.
2136 Insert_List_After (N, Statements (Alt));
2138 -- That leaves the case statement as a shell. So now we can kill all
2139 -- other alternatives in the case statement.
2141 Kill_Dead_Code (Expression (N));
2147 -- Loop through case alternatives, skipping pragmas, and skipping
2148 -- the one alternative that we select (and therefore retain).
2150 A := First (Alternatives (N));
2151 while Present (A) loop
2153 and then Nkind (A) = N_Case_Statement_Alternative
2155 Kill_Dead_Code (Statements (A), Warn_On_Deleted_Code);
2162 Rewrite (N, Make_Null_Statement (Loc));
2166 -- Here if the choice is not determined at compile time
2169 Last_Alt : constant Node_Id := Last (Alternatives (N));
2171 Others_Present : Boolean;
2172 Others_Node : Node_Id;
2174 Then_Stms : List_Id;
2175 Else_Stms : List_Id;
2178 if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then
2179 Others_Present := True;
2180 Others_Node := Last_Alt;
2182 Others_Present := False;
2185 -- First step is to worry about possible invalid argument. The RM
2186 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
2187 -- outside the base range), then Constraint_Error must be raised.
2189 -- Case of validity check required (validity checks are on, the
2190 -- expression is not known to be valid, and the case statement
2191 -- comes from source -- no need to validity check internally
2192 -- generated case statements).
2194 if Validity_Check_Default then
2195 Ensure_Valid (Expr);
2198 -- If there is only a single alternative, just replace it with the
2199 -- sequence of statements since obviously that is what is going to
2200 -- be executed in all cases.
2202 Len := List_Length (Alternatives (N));
2205 -- We still need to evaluate the expression if it has any
2208 Remove_Side_Effects (Expression (N));
2210 Insert_List_After (N, Statements (First (Alternatives (N))));
2212 -- That leaves the case statement as a shell. The alternative that
2213 -- will be executed is reset to a null list. So now we can kill
2214 -- the entire case statement.
2216 Kill_Dead_Code (Expression (N));
2217 Rewrite (N, Make_Null_Statement (Loc));
2221 -- An optimization. If there are only two alternatives, and only
2222 -- a single choice, then rewrite the whole case statement as an
2223 -- if statement, since this can result in subsequent optimizations.
2224 -- This helps not only with case statements in the source of a
2225 -- simple form, but also with generated code (discriminant check
2226 -- functions in particular)
2229 Chlist := Discrete_Choices (First (Alternatives (N)));
2231 if List_Length (Chlist) = 1 then
2232 Choice := First (Chlist);
2234 Then_Stms := Statements (First (Alternatives (N)));
2235 Else_Stms := Statements (Last (Alternatives (N)));
2237 -- For TRUE, generate "expression", not expression = true
2239 if Nkind (Choice) = N_Identifier
2240 and then Entity (Choice) = Standard_True
2242 Cond := Expression (N);
2244 -- For FALSE, generate "expression" and switch then/else
2246 elsif Nkind (Choice) = N_Identifier
2247 and then Entity (Choice) = Standard_False
2249 Cond := Expression (N);
2250 Else_Stms := Statements (First (Alternatives (N)));
2251 Then_Stms := Statements (Last (Alternatives (N)));
2253 -- For a range, generate "expression in range"
2255 elsif Nkind (Choice) = N_Range
2256 or else (Nkind (Choice) = N_Attribute_Reference
2257 and then Attribute_Name (Choice) = Name_Range)
2258 or else (Is_Entity_Name (Choice)
2259 and then Is_Type (Entity (Choice)))
2260 or else Nkind (Choice) = N_Subtype_Indication
2264 Left_Opnd => Expression (N),
2265 Right_Opnd => Relocate_Node (Choice));
2267 -- For any other subexpression "expression = value"
2272 Left_Opnd => Expression (N),
2273 Right_Opnd => Relocate_Node (Choice));
2276 -- Now rewrite the case as an IF
2279 Make_If_Statement (Loc,
2281 Then_Statements => Then_Stms,
2282 Else_Statements => Else_Stms));
2288 -- If the last alternative is not an Others choice, replace it with
2289 -- an N_Others_Choice. Note that we do not bother to call Analyze on
2290 -- the modified case statement, since it's only effect would be to
2291 -- compute the contents of the Others_Discrete_Choices which is not
2292 -- needed by the back end anyway.
2294 -- The reason we do this is that the back end always needs some
2295 -- default for a switch, so if we have not supplied one in the
2296 -- processing above for validity checking, then we need to supply
2299 if not Others_Present then
2300 Others_Node := Make_Others_Choice (Sloc (Last_Alt));
2301 Set_Others_Discrete_Choices
2302 (Others_Node, Discrete_Choices (Last_Alt));
2303 Set_Discrete_Choices (Last_Alt, New_List (Others_Node));
2306 end Expand_N_Case_Statement;
2308 -----------------------------
2309 -- Expand_N_Exit_Statement --
2310 -----------------------------
2312 -- The only processing required is to deal with a possible C/Fortran
2313 -- boolean value used as the condition for the exit statement.
2315 procedure Expand_N_Exit_Statement (N : Node_Id) is
2317 Adjust_Condition (Condition (N));
2318 end Expand_N_Exit_Statement;
2320 ----------------------------------------
2321 -- Expand_N_Extended_Return_Statement --
2322 ----------------------------------------
2324 -- If there is a Handled_Statement_Sequence, we rewrite this:
2326 -- return Result : T := <expression> do
2327 -- <handled_seq_of_stms>
2333 -- Result : T := <expression>;
2335 -- <handled_seq_of_stms>
2339 -- Otherwise (no Handled_Statement_Sequence), we rewrite this:
2341 -- return Result : T := <expression>;
2345 -- return <expression>;
2347 -- unless it's build-in-place or there's no <expression>, in which case
2351 -- Result : T := <expression>;
2356 -- Note that this case could have been written by the user as an extended
2357 -- return statement, or could have been transformed to this from a simple
2358 -- return statement.
2360 -- That is, we need to have a reified return object if there are statements
2361 -- (which might refer to it) or if we're doing build-in-place (so we can
2362 -- set its address to the final resting place or if there is no expression
2363 -- (in which case default initial values might need to be set).
2365 procedure Expand_N_Extended_Return_Statement (N : Node_Id) is
2366 Loc : constant Source_Ptr := Sloc (N);
2368 Return_Object_Entity : constant Entity_Id :=
2369 First_Entity (Return_Statement_Entity (N));
2370 Return_Object_Decl : constant Node_Id :=
2371 Parent (Return_Object_Entity);
2372 Parent_Function : constant Entity_Id :=
2373 Return_Applies_To (Return_Statement_Entity (N));
2374 Is_Build_In_Place : constant Boolean :=
2375 Is_Build_In_Place_Function (Parent_Function);
2377 Return_Stm : Node_Id;
2378 Statements : List_Id;
2379 Handled_Stm_Seq : Node_Id;
2383 function Move_Activation_Chain return Node_Id;
2384 -- Construct a call to System.Tasking.Stages.Move_Activation_Chain
2386 -- From current activation chain
2387 -- To activation chain passed in by the caller
2388 -- New_Master master passed in by the caller
2390 function Move_Final_List return Node_Id;
2391 -- Construct call to System.Finalization_Implementation.Move_Final_List
2394 -- From finalization list of the return statement
2395 -- To finalization list passed in by the caller
2397 ---------------------------
2398 -- Move_Activation_Chain --
2399 ---------------------------
2401 function Move_Activation_Chain return Node_Id is
2402 Activation_Chain_Formal : constant Entity_Id :=
2403 Build_In_Place_Formal
2404 (Parent_Function, BIP_Activation_Chain);
2405 To : constant Node_Id :=
2407 (Activation_Chain_Formal, Loc);
2408 Master_Formal : constant Entity_Id :=
2409 Build_In_Place_Formal
2410 (Parent_Function, BIP_Master);
2411 New_Master : constant Node_Id :=
2412 New_Reference_To (Master_Formal, Loc);
2414 Chain_Entity : Entity_Id;
2418 Chain_Entity := First_Entity (Return_Statement_Entity (N));
2419 while Chars (Chain_Entity) /= Name_uChain loop
2420 Chain_Entity := Next_Entity (Chain_Entity);
2424 Make_Attribute_Reference (Loc,
2425 Prefix => New_Reference_To (Chain_Entity, Loc),
2426 Attribute_Name => Name_Unrestricted_Access);
2427 -- ??? Not clear why "Make_Identifier (Loc, Name_uChain)" doesn't
2428 -- work, instead of "New_Reference_To (Chain_Entity, Loc)" above.
2431 Make_Procedure_Call_Statement (Loc,
2432 Name => New_Reference_To (RTE (RE_Move_Activation_Chain), Loc),
2433 Parameter_Associations => New_List (From, To, New_Master));
2434 end Move_Activation_Chain;
2436 ---------------------
2437 -- Move_Final_List --
2438 ---------------------
2440 function Move_Final_List return Node_Id is
2441 Flist : constant Entity_Id :=
2442 Finalization_Chain_Entity (Return_Statement_Entity (N));
2444 From : constant Node_Id := New_Reference_To (Flist, Loc);
2446 Caller_Final_List : constant Entity_Id :=
2447 Build_In_Place_Formal
2448 (Parent_Function, BIP_Final_List);
2450 To : constant Node_Id := New_Reference_To (Caller_Final_List, Loc);
2453 -- Catch cases where a finalization chain entity has not been
2454 -- associated with the return statement entity.
2456 pragma Assert (Present (Flist));
2458 -- Build required call
2461 Make_If_Statement (Loc,
2464 Left_Opnd => New_Copy (From),
2465 Right_Opnd => New_Node (N_Null, Loc)),
2468 Make_Procedure_Call_Statement (Loc,
2469 Name => New_Reference_To (RTE (RE_Move_Final_List), Loc),
2470 Parameter_Associations => New_List (From, To))));
2471 end Move_Final_List;
2473 -- Start of processing for Expand_N_Extended_Return_Statement
2476 if Nkind (Return_Object_Decl) = N_Object_Declaration then
2477 Exp := Expression (Return_Object_Decl);
2482 Handled_Stm_Seq := Handled_Statement_Sequence (N);
2484 -- Build a simple_return_statement that returns the return object when
2485 -- there is a statement sequence, or no expression, or the result will
2486 -- be built in place. Note however that we currently do this for all
2487 -- composite cases, even though nonlimited composite results are not yet
2488 -- built in place (though we plan to do so eventually).
2490 if Present (Handled_Stm_Seq)
2491 or else Is_Composite_Type (Etype (Parent_Function))
2494 if No (Handled_Stm_Seq) then
2495 Statements := New_List;
2497 -- If the extended return has a handled statement sequence, then wrap
2498 -- it in a block and use the block as the first statement.
2502 New_List (Make_Block_Statement (Loc,
2503 Declarations => New_List,
2504 Handled_Statement_Sequence => Handled_Stm_Seq));
2507 -- If control gets past the above Statements, we have successfully
2508 -- completed the return statement. If the result type has controlled
2509 -- parts and the return is for a build-in-place function, then we
2510 -- call Move_Final_List to transfer responsibility for finalization
2511 -- of the return object to the caller. An alternative would be to
2512 -- declare a Success flag in the function, initialize it to False,
2513 -- and set it to True here. Then move the Move_Final_List call into
2514 -- the cleanup code, and check Success. If Success then make a call
2515 -- to Move_Final_List else do finalization. Then we can remove the
2516 -- abort-deferral and the nulling-out of the From parameter from
2517 -- Move_Final_List. Note that the current method is not quite correct
2518 -- in the rather obscure case of a select-then-abort statement whose
2519 -- abortable part contains the return statement.
2521 -- We test the type of the expression as well as the return type
2522 -- of the function, because the latter may be a class-wide type
2523 -- which is always treated as controlled, while the expression itself
2524 -- has to have a definite type. The expression may be absent if a
2525 -- constrained aggregate has been expanded into component assignments
2526 -- so we have to check for this as well.
2528 if Is_Build_In_Place
2529 and then Controlled_Type (Etype (Parent_Function))
2531 if not Is_Class_Wide_Type (Etype (Parent_Function))
2534 and then Controlled_Type (Etype (Exp)))
2536 Append_To (Statements, Move_Final_List);
2540 -- Similarly to the above Move_Final_List, if the result type
2541 -- contains tasks, we call Move_Activation_Chain. Later, the cleanup
2542 -- code will call Complete_Master, which will terminate any
2543 -- unactivated tasks belonging to the return statement master. But
2544 -- Move_Activation_Chain updates their master to be that of the
2545 -- caller, so they will not be terminated unless the return statement
2546 -- completes unsuccessfully due to exception, abort, goto, or exit.
2547 -- As a formality, we test whether the function requires the result
2548 -- to be built in place, though that's necessarily true for the case
2549 -- of result types with task parts.
2551 if Is_Build_In_Place and Has_Task (Etype (Parent_Function)) then
2552 Append_To (Statements, Move_Activation_Chain);
2555 -- Build a simple_return_statement that returns the return object
2558 Make_Simple_Return_Statement (Loc,
2559 Expression => New_Occurrence_Of (Return_Object_Entity, Loc));
2560 Append_To (Statements, Return_Stm);
2563 Make_Handled_Sequence_Of_Statements (Loc, Statements);
2566 -- Case where we build a block
2568 if Present (Handled_Stm_Seq) then
2570 Make_Block_Statement (Loc,
2571 Declarations => Return_Object_Declarations (N),
2572 Handled_Statement_Sequence => Handled_Stm_Seq);
2574 -- We set the entity of the new block statement to be that of the
2575 -- return statement. This is necessary so that various fields, such
2576 -- as Finalization_Chain_Entity carry over from the return statement
2577 -- to the block. Note that this block is unusual, in that its entity
2578 -- is an E_Return_Statement rather than an E_Block.
2581 (Result, New_Occurrence_Of (Return_Statement_Entity (N), Loc));
2583 -- If the object decl was already rewritten as a renaming, then
2584 -- we don't want to do the object allocation and transformation of
2585 -- of the return object declaration to a renaming. This case occurs
2586 -- when the return object is initialized by a call to another
2587 -- build-in-place function, and that function is responsible for the
2588 -- allocation of the return object.
2590 if Is_Build_In_Place
2592 Nkind (Return_Object_Decl) = N_Object_Renaming_Declaration
2594 Set_By_Ref (Return_Stm); -- Return build-in-place results by ref
2596 elsif Is_Build_In_Place then
2598 -- Locate the implicit access parameter associated with the
2599 -- caller-supplied return object and convert the return
2600 -- statement's return object declaration to a renaming of a
2601 -- dereference of the access parameter. If the return object's
2602 -- declaration includes an expression that has not already been
2603 -- expanded as separate assignments, then add an assignment
2604 -- statement to ensure the return object gets initialized.
2607 -- Result : T [:= <expression>];
2614 -- Result : T renames FuncRA.all;
2615 -- [Result := <expression;]
2620 Return_Obj_Id : constant Entity_Id :=
2621 Defining_Identifier (Return_Object_Decl);
2622 Return_Obj_Typ : constant Entity_Id := Etype (Return_Obj_Id);
2623 Return_Obj_Expr : constant Node_Id :=
2624 Expression (Return_Object_Decl);
2625 Result_Subt : constant Entity_Id :=
2626 Etype (Parent_Function);
2627 Constr_Result : constant Boolean :=
2628 Is_Constrained (Result_Subt);
2629 Obj_Alloc_Formal : Entity_Id;
2630 Object_Access : Entity_Id;
2631 Obj_Acc_Deref : Node_Id;
2632 Init_Assignment : Node_Id := Empty;
2635 -- Build-in-place results must be returned by reference
2637 Set_By_Ref (Return_Stm);
2639 -- Retrieve the implicit access parameter passed by the caller
2642 Build_In_Place_Formal (Parent_Function, BIP_Object_Access);
2644 -- If the return object's declaration includes an expression
2645 -- and the declaration isn't marked as No_Initialization, then
2646 -- we need to generate an assignment to the object and insert
2647 -- it after the declaration before rewriting it as a renaming
2648 -- (otherwise we'll lose the initialization).
2650 if Present (Return_Obj_Expr)
2651 and then not No_Initialization (Return_Object_Decl)
2654 Make_Assignment_Statement (Loc,
2655 Name => New_Reference_To (Return_Obj_Id, Loc),
2656 Expression => Relocate_Node (Return_Obj_Expr));
2657 Set_Etype (Name (Init_Assignment), Etype (Return_Obj_Id));
2658 Set_Assignment_OK (Name (Init_Assignment));
2659 Set_No_Ctrl_Actions (Init_Assignment);
2661 Set_Parent (Name (Init_Assignment), Init_Assignment);
2662 Set_Parent (Expression (Init_Assignment), Init_Assignment);
2664 Set_Expression (Return_Object_Decl, Empty);
2666 if Is_Class_Wide_Type (Etype (Return_Obj_Id))
2667 and then not Is_Class_Wide_Type
2668 (Etype (Expression (Init_Assignment)))
2670 Rewrite (Expression (Init_Assignment),
2671 Make_Type_Conversion (Loc,
2674 (Etype (Return_Obj_Id), Loc),
2676 Relocate_Node (Expression (Init_Assignment))));
2679 -- In the case of functions where the calling context can
2680 -- determine the form of allocation needed, initialization
2681 -- is done with each part of the if statement that handles
2682 -- the different forms of allocation (this is true for
2683 -- unconstrained and tagged result subtypes).
2686 and then not Is_Tagged_Type (Underlying_Type (Result_Subt))
2688 Insert_After (Return_Object_Decl, Init_Assignment);
2692 -- When the function's subtype is unconstrained, a run-time
2693 -- test is needed to determine the form of allocation to use
2694 -- for the return object. The function has an implicit formal
2695 -- parameter indicating this. If the BIP_Alloc_Form formal has
2696 -- the value one, then the caller has passed access to an
2697 -- existing object for use as the return object. If the value
2698 -- is two, then the return object must be allocated on the
2699 -- secondary stack. Otherwise, the object must be allocated in
2700 -- a storage pool (currently only supported for the global
2701 -- heap, user-defined storage pools TBD ???). We generate an
2702 -- if statement to test the implicit allocation formal and
2703 -- initialize a local access value appropriately, creating
2704 -- allocators in the secondary stack and global heap cases.
2705 -- The special formal also exists and must be tested when the
2706 -- function has a tagged result, even when the result subtype
2707 -- is constrained, because in general such functions can be
2708 -- called in dispatching contexts and must be handled similarly
2709 -- to functions with a class-wide result.
2711 if not Constr_Result
2712 or else Is_Tagged_Type (Underlying_Type (Result_Subt))
2715 Build_In_Place_Formal (Parent_Function, BIP_Alloc_Form);
2718 Ref_Type : Entity_Id;
2719 Ptr_Type_Decl : Node_Id;
2720 Alloc_Obj_Id : Entity_Id;
2721 Alloc_Obj_Decl : Node_Id;
2722 Alloc_If_Stmt : Node_Id;
2723 SS_Allocator : Node_Id;
2724 Heap_Allocator : Node_Id;
2727 -- Reuse the itype created for the function's implicit
2728 -- access formal. This avoids the need to create a new
2729 -- access type here, plus it allows assigning the access
2730 -- formal directly without applying a conversion.
2732 -- Ref_Type := Etype (Object_Access);
2734 -- Create an access type designating the function's
2738 Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
2741 Make_Full_Type_Declaration (Loc,
2742 Defining_Identifier => Ref_Type,
2744 Make_Access_To_Object_Definition (Loc,
2745 All_Present => True,
2746 Subtype_Indication =>
2747 New_Reference_To (Return_Obj_Typ, Loc)));
2749 Insert_Before (Return_Object_Decl, Ptr_Type_Decl);
2751 -- Create an access object that will be initialized to an
2752 -- access value denoting the return object, either coming
2753 -- from an implicit access value passed in by the caller
2754 -- or from the result of an allocator.
2757 Make_Defining_Identifier (Loc,
2758 Chars => New_Internal_Name ('R'));
2759 Set_Etype (Alloc_Obj_Id, Ref_Type);
2762 Make_Object_Declaration (Loc,
2763 Defining_Identifier => Alloc_Obj_Id,
2764 Object_Definition => New_Reference_To
2767 Insert_Before (Return_Object_Decl, Alloc_Obj_Decl);
2769 -- Create allocators for both the secondary stack and
2770 -- global heap. If there's an initialization expression,
2771 -- then create these as initialized allocators.
2773 if Present (Return_Obj_Expr)
2774 and then not No_Initialization (Return_Object_Decl)
2777 Make_Allocator (Loc,
2779 Make_Qualified_Expression (Loc,
2781 New_Reference_To (Return_Obj_Typ, Loc),
2783 New_Copy_Tree (Return_Obj_Expr)));
2785 SS_Allocator := New_Copy_Tree (Heap_Allocator);
2788 -- If the function returns a class-wide type we cannot
2789 -- use the return type for the allocator. Instead we
2790 -- use the type of the expression, which must be an
2791 -- aggregate of a definite type.
2793 if Is_Class_Wide_Type (Return_Obj_Typ) then
2795 Make_Allocator (Loc,
2797 (Etype (Return_Obj_Expr), Loc));
2800 Make_Allocator (Loc,
2801 New_Reference_To (Return_Obj_Typ, Loc));
2804 -- If the object requires default initialization then
2805 -- that will happen later following the elaboration of
2806 -- the object renaming. If we don't turn it off here
2807 -- then the object will be default initialized twice.
2809 Set_No_Initialization (Heap_Allocator);
2811 SS_Allocator := New_Copy_Tree (Heap_Allocator);
2814 -- If the No_Allocators restriction is active, then only
2815 -- an allocator for secondary stack allocation is needed.
2817 if Restriction_Active (No_Allocators) then
2818 SS_Allocator := Heap_Allocator;
2819 Heap_Allocator := Make_Null (Loc);
2821 -- Otherwise the heap allocator may be needed, so we
2822 -- make another allocator for secondary stack allocation.
2825 SS_Allocator := New_Copy_Tree (Heap_Allocator);
2827 -- The heap allocator is marked Comes_From_Source
2828 -- since it corresponds to an explicit user-written
2829 -- allocator (that is, it will only be executed on
2830 -- behalf of callers that call the function as
2831 -- initialization for such an allocator). This
2832 -- prevents errors when No_Implicit_Heap_Allocation
2835 Set_Comes_From_Source (Heap_Allocator, True);
2838 -- The allocator is returned on the secondary stack. We
2839 -- don't do this on VM targets, since the SS is not used.
2841 if VM_Target = No_VM then
2842 Set_Storage_Pool (SS_Allocator, RTE (RE_SS_Pool));
2843 Set_Procedure_To_Call
2844 (SS_Allocator, RTE (RE_SS_Allocate));
2846 -- The allocator is returned on the secondary stack,
2847 -- so indicate that the function return, as well as
2848 -- the block that encloses the allocator, must not
2849 -- release it. The flags must be set now because the
2850 -- decision to use the secondary stack is done very
2851 -- late in the course of expanding the return
2852 -- statement, past the point where these flags are
2855 Set_Sec_Stack_Needed_For_Return (Parent_Function);
2856 Set_Sec_Stack_Needed_For_Return
2857 (Return_Statement_Entity (N));
2858 Set_Uses_Sec_Stack (Parent_Function);
2859 Set_Uses_Sec_Stack (Return_Statement_Entity (N));
2862 -- Create an if statement to test the BIP_Alloc_Form
2863 -- formal and initialize the access object to either the
2864 -- BIP_Object_Access formal (BIP_Alloc_Form = 0), the
2865 -- result of allocating the object in the secondary stack
2866 -- (BIP_Alloc_Form = 1), or else an allocator to create
2867 -- the return object in the heap (BIP_Alloc_Form = 2).
2869 -- ??? An unchecked type conversion must be made in the
2870 -- case of assigning the access object formal to the
2871 -- local access object, because a normal conversion would
2872 -- be illegal in some cases (such as converting access-
2873 -- to-unconstrained to access-to-constrained), but the
2874 -- the unchecked conversion will presumably fail to work
2875 -- right in just such cases. It's not clear at all how to
2879 Make_If_Statement (Loc,
2883 New_Reference_To (Obj_Alloc_Formal, Loc),
2885 Make_Integer_Literal (Loc,
2886 UI_From_Int (BIP_Allocation_Form'Pos
2887 (Caller_Allocation)))),
2889 New_List (Make_Assignment_Statement (Loc,
2892 (Alloc_Obj_Id, Loc),
2894 Make_Unchecked_Type_Conversion (Loc,
2896 New_Reference_To (Ref_Type, Loc),
2899 (Object_Access, Loc)))),
2901 New_List (Make_Elsif_Part (Loc,
2906 (Obj_Alloc_Formal, Loc),
2908 Make_Integer_Literal (Loc,
2910 BIP_Allocation_Form'Pos
2911 (Secondary_Stack)))),
2914 (Make_Assignment_Statement (Loc,
2917 (Alloc_Obj_Id, Loc),
2921 New_List (Make_Assignment_Statement (Loc,
2924 (Alloc_Obj_Id, Loc),
2928 -- If a separate initialization assignment was created
2929 -- earlier, append that following the assignment of the
2930 -- implicit access formal to the access object, to ensure
2931 -- that the return object is initialized in that case.
2932 -- In this situation, the target of the assignment must
2933 -- be rewritten to denote a dereference of the access to
2934 -- the return object passed in by the caller.
2936 if Present (Init_Assignment) then
2937 Rewrite (Name (Init_Assignment),
2938 Make_Explicit_Dereference (Loc,
2939 Prefix => New_Reference_To (Alloc_Obj_Id, Loc)));
2941 (Name (Init_Assignment), Etype (Return_Obj_Id));
2944 (Then_Statements (Alloc_If_Stmt),
2948 Insert_Before (Return_Object_Decl, Alloc_If_Stmt);
2950 -- Remember the local access object for use in the
2951 -- dereference of the renaming created below.
2953 Object_Access := Alloc_Obj_Id;
2957 -- Replace the return object declaration with a renaming of a
2958 -- dereference of the access value designating the return
2962 Make_Explicit_Dereference (Loc,
2963 Prefix => New_Reference_To (Object_Access, Loc));
2965 Rewrite (Return_Object_Decl,
2966 Make_Object_Renaming_Declaration (Loc,
2967 Defining_Identifier => Return_Obj_Id,
2968 Access_Definition => Empty,
2969 Subtype_Mark => New_Occurrence_Of
2970 (Return_Obj_Typ, Loc),
2971 Name => Obj_Acc_Deref));
2973 Set_Renamed_Object (Return_Obj_Id, Obj_Acc_Deref);
2977 -- Case where we do not build a block
2980 -- We're about to drop Return_Object_Declarations on the floor, so
2981 -- we need to insert it, in case it got expanded into useful code.
2983 Insert_List_Before (N, Return_Object_Declarations (N));
2985 -- Build simple_return_statement that returns the expression directly
2987 Return_Stm := Make_Simple_Return_Statement (Loc, Expression => Exp);
2989 Result := Return_Stm;
2992 -- Set the flag to prevent infinite recursion
2994 Set_Comes_From_Extended_Return_Statement (Return_Stm);
2996 Rewrite (N, Result);
2998 end Expand_N_Extended_Return_Statement;
3000 -----------------------------
3001 -- Expand_N_Goto_Statement --
3002 -----------------------------
3004 -- Add poll before goto if polling active
3006 procedure Expand_N_Goto_Statement (N : Node_Id) is
3008 Generate_Poll_Call (N);
3009 end Expand_N_Goto_Statement;
3011 ---------------------------
3012 -- Expand_N_If_Statement --
3013 ---------------------------
3015 -- First we deal with the case of C and Fortran convention boolean values,
3016 -- with zero/non-zero semantics.
3018 -- Second, we deal with the obvious rewriting for the cases where the
3019 -- condition of the IF is known at compile time to be True or False.
3021 -- Third, we remove elsif parts which have non-empty Condition_Actions
3022 -- and rewrite as independent if statements. For example:
3033 -- <<condition actions of y>>
3039 -- This rewriting is needed if at least one elsif part has a non-empty
3040 -- Condition_Actions list. We also do the same processing if there is a
3041 -- constant condition in an elsif part (in conjunction with the first
3042 -- processing step mentioned above, for the recursive call made to deal
3043 -- with the created inner if, this deals with properly optimizing the
3044 -- cases of constant elsif conditions).
3046 procedure Expand_N_If_Statement (N : Node_Id) is
3047 Loc : constant Source_Ptr := Sloc (N);
3052 Warn_If_Deleted : constant Boolean :=
3053 Warn_On_Deleted_Code and then Comes_From_Source (N);
3054 -- Indicates whether we want warnings when we delete branches of the
3055 -- if statement based on constant condition analysis. We never want
3056 -- these warnings for expander generated code.
3059 Adjust_Condition (Condition (N));
3061 -- The following loop deals with constant conditions for the IF. We
3062 -- need a loop because as we eliminate False conditions, we grab the
3063 -- first elsif condition and use it as the primary condition.
3065 while Compile_Time_Known_Value (Condition (N)) loop
3067 -- If condition is True, we can simply rewrite the if statement now
3068 -- by replacing it by the series of then statements.
3070 if Is_True (Expr_Value (Condition (N))) then
3072 -- All the else parts can be killed
3074 Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted);
3075 Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted);
3077 Hed := Remove_Head (Then_Statements (N));
3078 Insert_List_After (N, Then_Statements (N));
3082 -- If condition is False, then we can delete the condition and
3083 -- the Then statements
3086 -- We do not delete the condition if constant condition warnings
3087 -- are enabled, since otherwise we end up deleting the desired
3088 -- warning. Of course the backend will get rid of this True/False
3089 -- test anyway, so nothing is lost here.
3091 if not Constant_Condition_Warnings then
3092 Kill_Dead_Code (Condition (N));
3095 Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted);
3097 -- If there are no elsif statements, then we simply replace the
3098 -- entire if statement by the sequence of else statements.
3100 if No (Elsif_Parts (N)) then
3101 if No (Else_Statements (N))
3102 or else Is_Empty_List (Else_Statements (N))
3105 Make_Null_Statement (Sloc (N)));
3107 Hed := Remove_Head (Else_Statements (N));
3108 Insert_List_After (N, Else_Statements (N));
3114 -- If there are elsif statements, the first of them becomes the
3115 -- if/then section of the rebuilt if statement This is the case
3116 -- where we loop to reprocess this copied condition.
3119 Hed := Remove_Head (Elsif_Parts (N));
3120 Insert_Actions (N, Condition_Actions (Hed));
3121 Set_Condition (N, Condition (Hed));
3122 Set_Then_Statements (N, Then_Statements (Hed));
3124 -- Hed might have been captured as the condition determining
3125 -- the current value for an entity. Now it is detached from
3126 -- the tree, so a Current_Value pointer in the condition might
3127 -- need to be updated.
3129 Set_Current_Value_Condition (N);
3131 if Is_Empty_List (Elsif_Parts (N)) then
3132 Set_Elsif_Parts (N, No_List);
3138 -- Loop through elsif parts, dealing with constant conditions and
3139 -- possible expression actions that are present.
3141 if Present (Elsif_Parts (N)) then
3142 E := First (Elsif_Parts (N));
3143 while Present (E) loop
3144 Adjust_Condition (Condition (E));
3146 -- If there are condition actions, then rewrite the if statement
3147 -- as indicated above. We also do the same rewrite for a True or
3148 -- False condition. The further processing of this constant
3149 -- condition is then done by the recursive call to expand the
3150 -- newly created if statement
3152 if Present (Condition_Actions (E))
3153 or else Compile_Time_Known_Value (Condition (E))
3155 -- Note this is not an implicit if statement, since it is part
3156 -- of an explicit if statement in the source (or of an implicit
3157 -- if statement that has already been tested).
3160 Make_If_Statement (Sloc (E),
3161 Condition => Condition (E),
3162 Then_Statements => Then_Statements (E),
3163 Elsif_Parts => No_List,
3164 Else_Statements => Else_Statements (N));
3166 -- Elsif parts for new if come from remaining elsif's of parent
3168 while Present (Next (E)) loop
3169 if No (Elsif_Parts (New_If)) then
3170 Set_Elsif_Parts (New_If, New_List);
3173 Append (Remove_Next (E), Elsif_Parts (New_If));
3176 Set_Else_Statements (N, New_List (New_If));
3178 if Present (Condition_Actions (E)) then
3179 Insert_List_Before (New_If, Condition_Actions (E));
3184 if Is_Empty_List (Elsif_Parts (N)) then
3185 Set_Elsif_Parts (N, No_List);
3191 -- No special processing for that elsif part, move to next
3199 -- Some more optimizations applicable if we still have an IF statement
3201 if Nkind (N) /= N_If_Statement then
3205 -- Another optimization, special cases that can be simplified
3207 -- if expression then
3213 -- can be changed to:
3215 -- return expression;
3219 -- if expression then
3225 -- can be changed to:
3227 -- return not (expression);
3229 -- Only do these optimizations if we are at least at -O1 level
3231 if Optimization_Level > 0 then
3232 if Nkind (N) = N_If_Statement
3233 and then No (Elsif_Parts (N))
3234 and then Present (Else_Statements (N))
3235 and then List_Length (Then_Statements (N)) = 1
3236 and then List_Length (Else_Statements (N)) = 1
3239 Then_Stm : constant Node_Id := First (Then_Statements (N));
3240 Else_Stm : constant Node_Id := First (Else_Statements (N));
3243 if Nkind (Then_Stm) = N_Simple_Return_Statement
3245 Nkind (Else_Stm) = N_Simple_Return_Statement
3248 Then_Expr : constant Node_Id := Expression (Then_Stm);
3249 Else_Expr : constant Node_Id := Expression (Else_Stm);
3252 if Nkind (Then_Expr) = N_Identifier
3254 Nkind (Else_Expr) = N_Identifier
3256 if Entity (Then_Expr) = Standard_True
3257 and then Entity (Else_Expr) = Standard_False
3260 Make_Simple_Return_Statement (Loc,
3261 Expression => Relocate_Node (Condition (N))));
3265 elsif Entity (Then_Expr) = Standard_False
3266 and then Entity (Else_Expr) = Standard_True
3269 Make_Simple_Return_Statement (Loc,
3273 Relocate_Node (Condition (N)))));
3283 end Expand_N_If_Statement;
3285 -----------------------------
3286 -- Expand_N_Loop_Statement --
3287 -----------------------------
3289 -- 1. Deal with while condition for C/Fortran boolean
3290 -- 2. Deal with loops with a non-standard enumeration type range
3291 -- 3. Deal with while loops where Condition_Actions is set
3292 -- 4. Insert polling call if required
3294 procedure Expand_N_Loop_Statement (N : Node_Id) is
3295 Loc : constant Source_Ptr := Sloc (N);
3296 Isc : constant Node_Id := Iteration_Scheme (N);
3299 if Present (Isc) then
3300 Adjust_Condition (Condition (Isc));
3303 if Is_Non_Empty_List (Statements (N)) then
3304 Generate_Poll_Call (First (Statements (N)));
3307 -- Nothing more to do for plain loop with no iteration scheme
3313 -- Note: we do not have to worry about validity checking of the for loop
3314 -- range bounds here, since they were frozen with constant declarations
3315 -- and it is during that process that the validity checking is done.
3317 -- Handle the case where we have a for loop with the range type being an
3318 -- enumeration type with non-standard representation. In this case we
3321 -- for x in [reverse] a .. b loop
3327 -- for xP in [reverse] integer
3328 -- range etype'Pos (a) .. etype'Pos (b) loop
3330 -- x : constant etype := Pos_To_Rep (xP);
3336 if Present (Loop_Parameter_Specification (Isc)) then
3338 LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
3339 Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
3340 Ltype : constant Entity_Id := Etype (Loop_Id);
3341 Btype : constant Entity_Id := Base_Type (Ltype);
3346 if not Is_Enumeration_Type (Btype)
3347 or else No (Enum_Pos_To_Rep (Btype))
3353 Make_Defining_Identifier (Loc,
3354 Chars => New_External_Name (Chars (Loop_Id), 'P'));
3356 -- If the type has a contiguous representation, successive values
3357 -- can be generated as offsets from the first literal.
3359 if Has_Contiguous_Rep (Btype) then
3361 Unchecked_Convert_To (Btype,
3364 Make_Integer_Literal (Loc,
3365 Enumeration_Rep (First_Literal (Btype))),
3366 Right_Opnd => New_Reference_To (New_Id, Loc)));
3368 -- Use the constructed array Enum_Pos_To_Rep
3371 Make_Indexed_Component (Loc,
3372 Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc),
3373 Expressions => New_List (New_Reference_To (New_Id, Loc)));
3377 Make_Loop_Statement (Loc,
3378 Identifier => Identifier (N),
3381 Make_Iteration_Scheme (Loc,
3382 Loop_Parameter_Specification =>
3383 Make_Loop_Parameter_Specification (Loc,
3384 Defining_Identifier => New_Id,
3385 Reverse_Present => Reverse_Present (LPS),
3387 Discrete_Subtype_Definition =>
3388 Make_Subtype_Indication (Loc,
3391 New_Reference_To (Standard_Natural, Loc),
3394 Make_Range_Constraint (Loc,
3399 Make_Attribute_Reference (Loc,
3401 New_Reference_To (Btype, Loc),
3403 Attribute_Name => Name_Pos,
3405 Expressions => New_List (
3407 (Type_Low_Bound (Ltype)))),
3410 Make_Attribute_Reference (Loc,
3412 New_Reference_To (Btype, Loc),
3414 Attribute_Name => Name_Pos,
3416 Expressions => New_List (
3418 (Type_High_Bound (Ltype))))))))),
3420 Statements => New_List (
3421 Make_Block_Statement (Loc,
3422 Declarations => New_List (
3423 Make_Object_Declaration (Loc,
3424 Defining_Identifier => Loop_Id,
3425 Constant_Present => True,
3426 Object_Definition => New_Reference_To (Ltype, Loc),
3427 Expression => Expr)),
3429 Handled_Statement_Sequence =>
3430 Make_Handled_Sequence_Of_Statements (Loc,
3431 Statements => Statements (N)))),
3433 End_Label => End_Label (N)));
3437 -- Second case, if we have a while loop with Condition_Actions set, then
3438 -- we change it into a plain loop:
3447 -- <<condition actions>>
3453 and then Present (Condition_Actions (Isc))
3460 Make_Exit_Statement (Sloc (Condition (Isc)),
3462 Make_Op_Not (Sloc (Condition (Isc)),
3463 Right_Opnd => Condition (Isc)));
3465 Prepend (ES, Statements (N));
3466 Insert_List_Before (ES, Condition_Actions (Isc));
3468 -- This is not an implicit loop, since it is generated in response
3469 -- to the loop statement being processed. If this is itself
3470 -- implicit, the restriction has already been checked. If not,
3471 -- it is an explicit loop.
3474 Make_Loop_Statement (Sloc (N),
3475 Identifier => Identifier (N),
3476 Statements => Statements (N),
3477 End_Label => End_Label (N)));
3482 end Expand_N_Loop_Statement;
3484 --------------------------------------
3485 -- Expand_N_Simple_Return_Statement --
3486 --------------------------------------
3488 procedure Expand_N_Simple_Return_Statement (N : Node_Id) is
3490 -- Defend against previous errors (i.e. the return statement calls a
3491 -- function that is not available in configurable runtime).
3493 if Present (Expression (N))
3494 and then Nkind (Expression (N)) = N_Empty
3499 -- Distinguish the function and non-function cases:
3501 case Ekind (Return_Applies_To (Return_Statement_Entity (N))) is
3504 E_Generic_Function =>
3505 Expand_Simple_Function_Return (N);
3508 E_Generic_Procedure |
3511 E_Return_Statement =>
3512 Expand_Non_Function_Return (N);
3515 raise Program_Error;
3519 when RE_Not_Available =>
3521 end Expand_N_Simple_Return_Statement;
3523 --------------------------------
3524 -- Expand_Non_Function_Return --
3525 --------------------------------
3527 procedure Expand_Non_Function_Return (N : Node_Id) is
3528 pragma Assert (No (Expression (N)));
3530 Loc : constant Source_Ptr := Sloc (N);
3531 Scope_Id : Entity_Id :=
3532 Return_Applies_To (Return_Statement_Entity (N));
3533 Kind : constant Entity_Kind := Ekind (Scope_Id);
3536 Goto_Stat : Node_Id;
3540 -- Call postconditions procedure if procedure with active postconditions
3542 if Ekind (Scope_Id) = E_Procedure
3543 and then Has_Postconditions (Scope_Id)
3546 Make_Procedure_Call_Statement (Loc,
3547 Name => Make_Identifier (Loc, Name_uPostconditions)));
3550 -- If it is a return from a procedure do no extra steps
3552 if Kind = E_Procedure or else Kind = E_Generic_Procedure then
3555 -- If it is a nested return within an extended one, replace it with a
3556 -- return of the previously declared return object.
3558 elsif Kind = E_Return_Statement then
3560 Make_Simple_Return_Statement (Loc,
3562 New_Occurrence_Of (First_Entity (Scope_Id), Loc)));
3563 Set_Comes_From_Extended_Return_Statement (N);
3564 Set_Return_Statement_Entity (N, Scope_Id);
3565 Expand_Simple_Function_Return (N);
3569 pragma Assert (Is_Entry (Scope_Id));
3571 -- Look at the enclosing block to see whether the return is from an
3572 -- accept statement or an entry body.
3574 for J in reverse 0 .. Scope_Stack.Last loop
3575 Scope_Id := Scope_Stack.Table (J).Entity;
3576 exit when Is_Concurrent_Type (Scope_Id);
3579 -- If it is a return from accept statement it is expanded as call to
3580 -- RTS Complete_Rendezvous and a goto to the end of the accept body.
3582 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
3583 -- Expand_N_Accept_Alternative in exp_ch9.adb)
3585 if Is_Task_Type (Scope_Id) then
3588 Make_Procedure_Call_Statement (Loc,
3589 Name => New_Reference_To
3590 (RTE (RE_Complete_Rendezvous), Loc));
3591 Insert_Before (N, Call);
3592 -- why not insert actions here???
3595 Acc_Stat := Parent (N);
3596 while Nkind (Acc_Stat) /= N_Accept_Statement loop
3597 Acc_Stat := Parent (Acc_Stat);
3600 Lab_Node := Last (Statements
3601 (Handled_Statement_Sequence (Acc_Stat)));
3603 Goto_Stat := Make_Goto_Statement (Loc,
3604 Name => New_Occurrence_Of
3605 (Entity (Identifier (Lab_Node)), Loc));
3607 Set_Analyzed (Goto_Stat);
3609 Rewrite (N, Goto_Stat);
3612 -- If it is a return from an entry body, put a Complete_Entry_Body call
3613 -- in front of the return.
3615 elsif Is_Protected_Type (Scope_Id) then
3617 Make_Procedure_Call_Statement (Loc,
3619 New_Reference_To (RTE (RE_Complete_Entry_Body), Loc),
3620 Parameter_Associations => New_List (
3621 Make_Attribute_Reference (Loc,
3624 (Find_Protection_Object (Current_Scope), Loc),
3626 Name_Unchecked_Access)));
3628 Insert_Before (N, Call);
3631 end Expand_Non_Function_Return;
3633 -----------------------------------
3634 -- Expand_Simple_Function_Return --
3635 -----------------------------------
3637 -- The "simple" comes from the syntax rule simple_return_statement.
3638 -- The semantics are not at all simple!
3640 procedure Expand_Simple_Function_Return (N : Node_Id) is
3641 Loc : constant Source_Ptr := Sloc (N);
3643 Scope_Id : constant Entity_Id :=
3644 Return_Applies_To (Return_Statement_Entity (N));
3645 -- The function we are returning from
3647 R_Type : constant Entity_Id := Etype (Scope_Id);
3648 -- The result type of the function
3650 Utyp : constant Entity_Id := Underlying_Type (R_Type);
3652 Exp : constant Node_Id := Expression (N);
3653 pragma Assert (Present (Exp));
3655 Exptyp : constant Entity_Id := Etype (Exp);
3656 -- The type of the expression (not necessarily the same as R_Type)
3659 -- For the case of a simple return that does not come from an extended
3660 -- return, in the case of Ada 2005 where we are returning a limited
3661 -- type, we rewrite "return <expression>;" to be:
3663 -- return _anon_ : <return_subtype> := <expression>
3665 -- The expansion produced by Expand_N_Extended_Return_Statement will
3666 -- contain simple return statements (for example, a block containing
3667 -- simple return of the return object), which brings us back here with
3668 -- Comes_From_Extended_Return_Statement set. The reason for the barrier
3669 -- checking for a simple return that does not come from an extended
3670 -- return is to avoid this infinite recursion.
3672 -- The reason for this design is that for Ada 2005 limited returns, we
3673 -- need to reify the return object, so we can build it "in place", and
3674 -- we need a block statement to hang finalization and tasking stuff.
3676 -- ??? In order to avoid disruption, we avoid translating to extended
3677 -- return except in the cases where we really need to (Ada 2005 for
3678 -- inherently limited). We might prefer to do this translation in all
3679 -- cases (except perhaps for the case of Ada 95 inherently limited),
3680 -- in order to fully exercise the Expand_N_Extended_Return_Statement
3681 -- code. This would also allow us to to the build-in-place optimization
3682 -- for efficiency even in cases where it is semantically not required.
3684 -- As before, we check the type of the return expression rather than the
3685 -- return type of the function, because the latter may be a limited
3686 -- class-wide interface type, which is not a limited type, even though
3687 -- the type of the expression may be.
3689 if not Comes_From_Extended_Return_Statement (N)
3690 and then Is_Inherently_Limited_Type (Etype (Expression (N)))
3691 and then Ada_Version >= Ada_05
3692 and then not Debug_Flag_Dot_L
3695 Return_Object_Entity : constant Entity_Id :=
3696 Make_Defining_Identifier (Loc,
3697 New_Internal_Name ('R'));
3698 Subtype_Ind : Node_Id;
3701 -- If the result type of the function is class-wide and the
3702 -- expression has a specific type, then we use the expression's
3703 -- type as the type of the return object. In cases where the
3704 -- expression is an aggregate that is built in place, this avoids
3705 -- the need for an expensive conversion of the return object to
3706 -- the specific type on assignments to the individual components.
3708 if Is_Class_Wide_Type (R_Type)
3709 and then not Is_Class_Wide_Type (Etype (Exp))
3711 Subtype_Ind := New_Occurrence_Of (Etype (Exp), Loc);
3713 Subtype_Ind := New_Occurrence_Of (R_Type, Loc);
3717 Obj_Decl : constant Node_Id :=
3718 Make_Object_Declaration (Loc,
3719 Defining_Identifier => Return_Object_Entity,
3720 Object_Definition => Subtype_Ind,
3723 Ext : constant Node_Id := Make_Extended_Return_Statement (Loc,
3724 Return_Object_Declarations => New_List (Obj_Decl));
3734 -- Here we have a simple return statement that is part of the expansion
3735 -- of an extended return statement (either written by the user, or
3736 -- generated by the above code).
3738 -- Always normalize C/Fortran boolean result. This is not always needed,
3739 -- but it seems a good idea to minimize the passing around of non-
3740 -- normalized values, and in any case this handles the processing of
3741 -- barrier functions for protected types, which turn the condition into
3742 -- a return statement.
3744 if Is_Boolean_Type (Exptyp)
3745 and then Nonzero_Is_True (Exptyp)
3747 Adjust_Condition (Exp);
3748 Adjust_Result_Type (Exp, Exptyp);
3751 -- Do validity check if enabled for returns
3753 if Validity_Checks_On
3754 and then Validity_Check_Returns
3759 -- Check the result expression of a scalar function against the subtype
3760 -- of the function by inserting a conversion. This conversion must
3761 -- eventually be performed for other classes of types, but for now it's
3762 -- only done for scalars.
3765 if Is_Scalar_Type (Exptyp) then
3766 Rewrite (Exp, Convert_To (R_Type, Exp));
3770 -- Deal with returning variable length objects and controlled types
3772 -- Nothing to do if we are returning by reference, or this is not a
3773 -- type that requires special processing (indicated by the fact that
3774 -- it requires a cleanup scope for the secondary stack case).
3776 if Is_Inherently_Limited_Type (Exptyp)
3777 or else Is_Limited_Interface (Exptyp)
3781 elsif not Requires_Transient_Scope (R_Type) then
3783 -- Mutable records with no variable length components are not
3784 -- returned on the sec-stack, so we need to make sure that the
3785 -- backend will only copy back the size of the actual value, and not
3786 -- the maximum size. We create an actual subtype for this purpose.
3789 Ubt : constant Entity_Id := Underlying_Type (Base_Type (Exptyp));
3793 if Has_Discriminants (Ubt)
3794 and then not Is_Constrained (Ubt)
3795 and then not Has_Unchecked_Union (Ubt)
3797 Decl := Build_Actual_Subtype (Ubt, Exp);
3798 Ent := Defining_Identifier (Decl);
3799 Insert_Action (Exp, Decl);
3800 Rewrite (Exp, Unchecked_Convert_To (Ent, Exp));
3801 Analyze_And_Resolve (Exp);
3805 -- Here if secondary stack is used
3808 -- Make sure that no surrounding block will reclaim the secondary
3809 -- stack on which we are going to put the result. Not only may this
3810 -- introduce secondary stack leaks but worse, if the reclamation is
3811 -- done too early, then the result we are returning may get
3818 while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop
3819 Set_Sec_Stack_Needed_For_Return (S, True);
3820 S := Enclosing_Dynamic_Scope (S);
3824 -- Optimize the case where the result is a function call. In this
3825 -- case either the result is already on the secondary stack, or is
3826 -- already being returned with the stack pointer depressed and no
3827 -- further processing is required except to set the By_Ref flag to
3828 -- ensure that gigi does not attempt an extra unnecessary copy.
3829 -- (actually not just unnecessary but harmfully wrong in the case
3830 -- of a controlled type, where gigi does not know how to do a copy).
3831 -- To make up for a gcc 2.8.1 deficiency (???), we perform
3832 -- the copy for array types if the constrained status of the
3833 -- target type is different from that of the expression.
3835 if Requires_Transient_Scope (Exptyp)
3837 (not Is_Array_Type (Exptyp)
3838 or else Is_Constrained (Exptyp) = Is_Constrained (R_Type)
3839 or else CW_Or_Controlled_Type (Utyp))
3840 and then Nkind (Exp) = N_Function_Call
3844 -- Remove side effects from the expression now so that other parts
3845 -- of the expander do not have to reanalyze this node without this
3848 Rewrite (Exp, Duplicate_Subexpr_No_Checks (Exp));
3850 -- For controlled types, do the allocation on the secondary stack
3851 -- manually in order to call adjust at the right time:
3853 -- type Anon1 is access R_Type;
3854 -- for Anon1'Storage_pool use ss_pool;
3855 -- Anon2 : anon1 := new R_Type'(expr);
3856 -- return Anon2.all;
3858 -- We do the same for classwide types that are not potentially
3859 -- controlled (by the virtue of restriction No_Finalization) because
3860 -- gigi is not able to properly allocate class-wide types.
3862 elsif CW_Or_Controlled_Type (Utyp) then
3864 Loc : constant Source_Ptr := Sloc (N);
3865 Temp : constant Entity_Id :=
3866 Make_Defining_Identifier (Loc,
3867 Chars => New_Internal_Name ('R'));
3868 Acc_Typ : constant Entity_Id :=
3869 Make_Defining_Identifier (Loc,
3870 Chars => New_Internal_Name ('A'));
3871 Alloc_Node : Node_Id;
3874 Set_Ekind (Acc_Typ, E_Access_Type);
3876 Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool));
3879 Make_Allocator (Loc,
3881 Make_Qualified_Expression (Loc,
3882 Subtype_Mark => New_Reference_To (Etype (Exp), Loc),
3883 Expression => Relocate_Node (Exp)));
3885 Insert_List_Before_And_Analyze (N, New_List (
3886 Make_Full_Type_Declaration (Loc,
3887 Defining_Identifier => Acc_Typ,
3889 Make_Access_To_Object_Definition (Loc,
3890 Subtype_Indication =>
3891 New_Reference_To (R_Type, Loc))),
3893 Make_Object_Declaration (Loc,
3894 Defining_Identifier => Temp,
3895 Object_Definition => New_Reference_To (Acc_Typ, Loc),
3896 Expression => Alloc_Node)));
3899 Make_Explicit_Dereference (Loc,
3900 Prefix => New_Reference_To (Temp, Loc)));
3902 Analyze_And_Resolve (Exp, R_Type);
3905 -- Otherwise use the gigi mechanism to allocate result on the
3909 Set_Storage_Pool (N, RTE (RE_SS_Pool));
3911 -- If we are generating code for the VM do not use
3912 -- SS_Allocate since everything is heap-allocated anyway.
3914 if VM_Target = No_VM then
3915 Set_Procedure_To_Call (N, RTE (RE_SS_Allocate));
3920 -- Implement the rules of 6.5(8-10), which require a tag check in the
3921 -- case of a limited tagged return type, and tag reassignment for
3922 -- nonlimited tagged results. These actions are needed when the return
3923 -- type is a specific tagged type and the result expression is a
3924 -- conversion or a formal parameter, because in that case the tag of the
3925 -- expression might differ from the tag of the specific result type.
3927 if Is_Tagged_Type (Utyp)
3928 and then not Is_Class_Wide_Type (Utyp)
3929 and then (Nkind_In (Exp, N_Type_Conversion,
3930 N_Unchecked_Type_Conversion)
3931 or else (Is_Entity_Name (Exp)
3932 and then Ekind (Entity (Exp)) in Formal_Kind))
3934 -- When the return type is limited, perform a check that the
3935 -- tag of the result is the same as the tag of the return type.
3937 if Is_Limited_Type (R_Type) then
3939 Make_Raise_Constraint_Error (Loc,
3943 Make_Selected_Component (Loc,
3944 Prefix => Duplicate_Subexpr (Exp),
3946 New_Reference_To (First_Tag_Component (Utyp), Loc)),
3948 Unchecked_Convert_To (RTE (RE_Tag),
3951 (Access_Disp_Table (Base_Type (Utyp)))),
3953 Reason => CE_Tag_Check_Failed));
3955 -- If the result type is a specific nonlimited tagged type, then we
3956 -- have to ensure that the tag of the result is that of the result
3957 -- type. This is handled by making a copy of the expression in the
3958 -- case where it might have a different tag, namely when the
3959 -- expression is a conversion or a formal parameter. We create a new
3960 -- object of the result type and initialize it from the expression,
3961 -- which will implicitly force the tag to be set appropriately.
3965 Result_Id : constant Entity_Id :=
3966 Make_Defining_Identifier (Loc,
3967 Chars => New_Internal_Name ('R'));
3968 Result_Exp : constant Node_Id :=
3969 New_Reference_To (Result_Id, Loc);
3970 Result_Obj : constant Node_Id :=
3971 Make_Object_Declaration (Loc,
3972 Defining_Identifier => Result_Id,
3973 Object_Definition =>
3974 New_Reference_To (R_Type, Loc),
3975 Constant_Present => True,
3976 Expression => Relocate_Node (Exp));
3979 Set_Assignment_OK (Result_Obj);
3980 Insert_Action (Exp, Result_Obj);
3982 Rewrite (Exp, Result_Exp);
3983 Analyze_And_Resolve (Exp, R_Type);
3987 -- Ada 2005 (AI-344): If the result type is class-wide, then insert
3988 -- a check that the level of the return expression's underlying type
3989 -- is not deeper than the level of the master enclosing the function.
3990 -- Always generate the check when the type of the return expression
3991 -- is class-wide, when it's a type conversion, or when it's a formal
3992 -- parameter. Otherwise, suppress the check in the case where the
3993 -- return expression has a specific type whose level is known not to
3994 -- be statically deeper than the function's result type.
3996 -- Note: accessibility check is skipped in the VM case, since there
3997 -- does not seem to be any practical way to implement this check.
3999 elsif Ada_Version >= Ada_05
4000 and then VM_Target = No_VM
4001 and then Is_Class_Wide_Type (R_Type)
4002 and then not Scope_Suppress (Accessibility_Check)
4004 (Is_Class_Wide_Type (Etype (Exp))
4005 or else Nkind_In (Exp, N_Type_Conversion,
4006 N_Unchecked_Type_Conversion)
4007 or else (Is_Entity_Name (Exp)
4008 and then Ekind (Entity (Exp)) in Formal_Kind)
4009 or else Scope_Depth (Enclosing_Dynamic_Scope (Etype (Exp))) >
4010 Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))
4016 -- Ada 2005 (AI-251): In class-wide interface objects we displace
4017 -- "this" to reference the base of the object --- required to get
4018 -- access to the TSD of the object.
4020 if Is_Class_Wide_Type (Etype (Exp))
4021 and then Is_Interface (Etype (Exp))
4022 and then Nkind (Exp) = N_Explicit_Dereference
4025 Make_Explicit_Dereference (Loc,
4026 Unchecked_Convert_To (RTE (RE_Tag_Ptr),
4027 Make_Function_Call (Loc,
4028 Name => New_Reference_To (RTE (RE_Base_Address), Loc),
4029 Parameter_Associations => New_List (
4030 Unchecked_Convert_To (RTE (RE_Address),
4031 Duplicate_Subexpr (Prefix (Exp)))))));
4034 Make_Attribute_Reference (Loc,
4035 Prefix => Duplicate_Subexpr (Exp),
4036 Attribute_Name => Name_Tag);
4040 Make_Raise_Program_Error (Loc,
4044 Build_Get_Access_Level (Loc, Tag_Node),
4046 Make_Integer_Literal (Loc,
4047 Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))),
4048 Reason => PE_Accessibility_Check_Failed));
4052 -- If we are returning an object that may not be bit-aligned, then
4053 -- copy the value into a temporary first. This copy may need to expand
4054 -- to a loop of component operations..
4056 if Is_Possibly_Unaligned_Slice (Exp)
4057 or else Is_Possibly_Unaligned_Object (Exp)
4060 Tnn : constant Entity_Id :=
4061 Make_Defining_Identifier (Loc, New_Internal_Name ('T'));
4064 Make_Object_Declaration (Loc,
4065 Defining_Identifier => Tnn,
4066 Constant_Present => True,
4067 Object_Definition => New_Occurrence_Of (R_Type, Loc),
4068 Expression => Relocate_Node (Exp)),
4069 Suppress => All_Checks);
4070 Rewrite (Exp, New_Occurrence_Of (Tnn, Loc));
4074 -- Generate call to postcondition checks if they are present
4076 if Ekind (Scope_Id) = E_Function
4077 and then Has_Postconditions (Scope_Id)
4079 -- We are going to reference the returned value twice in this case,
4080 -- once in the call to _Postconditions, and once in the actual return
4081 -- statement, but we can't have side effects happening twice, and in
4082 -- any case for efficiency we don't want to do the computation twice.
4084 -- If the returned expression is an entity name, we don't need to
4085 -- worry since it is efficient and safe to reference it twice, that's
4086 -- also true for literals other than string literals, and for the
4087 -- case of X.all where X is an entity name.
4089 if Is_Entity_Name (Exp)
4090 or else Nkind_In (Exp, N_Character_Literal,
4093 or else (Nkind (Exp) = N_Explicit_Dereference
4094 and then Is_Entity_Name (Prefix (Exp)))
4098 -- Otherwise we are going to need a temporary to capture the value
4102 Tnn : constant Entity_Id :=
4103 Make_Defining_Identifier (Loc, New_Internal_Name ('T'));
4106 -- For a complex expression of an elementary type, capture
4107 -- value in the temporary and use it as the reference.
4109 if Is_Elementary_Type (R_Type) then
4111 Make_Object_Declaration (Loc,
4112 Defining_Identifier => Tnn,
4113 Constant_Present => True,
4114 Object_Definition => New_Occurrence_Of (R_Type, Loc),
4115 Expression => Relocate_Node (Exp)),
4116 Suppress => All_Checks);
4118 Rewrite (Exp, New_Occurrence_Of (Tnn, Loc));
4120 -- If we have something we can rename, generate a renaming of
4121 -- the object and replace the expression with a reference
4123 elsif Is_Object_Reference (Exp) then
4125 Make_Object_Renaming_Declaration (Loc,
4126 Defining_Identifier => Tnn,
4127 Subtype_Mark => New_Occurrence_Of (R_Type, Loc),
4128 Name => Relocate_Node (Exp)),
4129 Suppress => All_Checks);
4131 Rewrite (Exp, New_Occurrence_Of (Tnn, Loc));
4133 -- Otherwise we have something like a string literal or an
4134 -- aggregate. We could copy the value, but that would be
4135 -- inefficient. Instead we make a reference to the value and
4136 -- capture this reference with a renaming, the expression is
4137 -- then replaced by a dereference of this renaming.
4140 -- For now, copy the value, since the code below does not
4141 -- seem to work correctly ???
4144 Make_Object_Declaration (Loc,
4145 Defining_Identifier => Tnn,
4146 Constant_Present => True,
4147 Object_Definition => New_Occurrence_Of (R_Type, Loc),
4148 Expression => Relocate_Node (Exp)),
4149 Suppress => All_Checks);
4151 Rewrite (Exp, New_Occurrence_Of (Tnn, Loc));
4153 -- Insert_Action (Exp,
4154 -- Make_Object_Renaming_Declaration (Loc,
4155 -- Defining_Identifier => Tnn,
4156 -- Access_Definition =>
4157 -- Make_Access_Definition (Loc,
4158 -- All_Present => True,
4159 -- Subtype_Mark => New_Occurrence_Of (R_Type, Loc)),
4161 -- Make_Reference (Loc,
4162 -- Prefix => Relocate_Node (Exp))),
4163 -- Suppress => All_Checks);
4166 -- Make_Explicit_Dereference (Loc,
4167 -- Prefix => New_Occurrence_Of (Tnn, Loc)));
4172 -- Generate call to _postconditions
4175 Make_Procedure_Call_Statement (Loc,
4176 Name => Make_Identifier (Loc, Name_uPostconditions),
4177 Parameter_Associations => New_List (Duplicate_Subexpr (Exp))));
4179 end Expand_Simple_Function_Return;
4181 ------------------------------
4182 -- Make_Tag_Ctrl_Assignment --
4183 ------------------------------
4185 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is
4186 Loc : constant Source_Ptr := Sloc (N);
4187 L : constant Node_Id := Name (N);
4188 T : constant Entity_Id := Underlying_Type (Etype (L));
4190 Ctrl_Act : constant Boolean := Controlled_Type (T)
4191 and then not No_Ctrl_Actions (N);
4193 Save_Tag : constant Boolean := Is_Tagged_Type (T)
4194 and then not No_Ctrl_Actions (N)
4195 and then VM_Target = No_VM;
4196 -- Tags are not saved and restored when VM_Target because VM tags are
4197 -- represented implicitly in objects.
4200 Tag_Tmp : Entity_Id;
4202 Prev_Tmp : Entity_Id;
4203 Next_Tmp : Entity_Id;
4209 -- Finalize the target of the assignment when controlled.
4210 -- We have two exceptions here:
4212 -- 1. If we are in an init proc since it is an initialization
4213 -- more than an assignment
4215 -- 2. If the left-hand side is a temporary that was not initialized
4216 -- (or the parent part of a temporary since it is the case in
4217 -- extension aggregates). Such a temporary does not come from
4218 -- source. We must examine the original node for the prefix, because
4219 -- it may be a component of an entry formal, in which case it has
4220 -- been rewritten and does not appear to come from source either.
4222 -- Case of init proc
4224 if not Ctrl_Act then
4227 -- The left hand side is an uninitialized temporary object
4229 elsif Nkind (L) = N_Type_Conversion
4230 and then Is_Entity_Name (Expression (L))
4231 and then Nkind (Parent (Entity (Expression (L))))
4232 = N_Object_Declaration
4233 and then No_Initialization (Parent (Entity (Expression (L))))
4238 Append_List_To (Res,
4240 Ref => Duplicate_Subexpr_No_Checks (L),
4242 With_Detach => New_Reference_To (Standard_False, Loc)));
4245 -- Save the Tag in a local variable Tag_Tmp
4249 Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
4252 Make_Object_Declaration (Loc,
4253 Defining_Identifier => Tag_Tmp,
4254 Object_Definition => New_Reference_To (RTE (RE_Tag), Loc),
4256 Make_Selected_Component (Loc,
4257 Prefix => Duplicate_Subexpr_No_Checks (L),
4258 Selector_Name => New_Reference_To (First_Tag_Component (T),
4261 -- Otherwise Tag_Tmp not used
4268 if VM_Target /= No_VM then
4270 -- Cannot assign part of the object in a VM context, so instead
4271 -- fallback to the previous mechanism, even though it is not
4272 -- completely correct ???
4274 -- Save the Finalization Pointers in local variables Prev_Tmp and
4275 -- Next_Tmp. For objects with Has_Controlled_Component set, these
4276 -- pointers are in the Record_Controller
4278 Ctrl_Ref := Duplicate_Subexpr (L);
4280 if Has_Controlled_Component (T) then
4282 Make_Selected_Component (Loc,
4285 New_Reference_To (Controller_Component (T), Loc));
4289 Make_Defining_Identifier (Loc, New_Internal_Name ('B'));
4292 Make_Object_Declaration (Loc,
4293 Defining_Identifier => Prev_Tmp,
4295 Object_Definition =>
4296 New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
4299 Make_Selected_Component (Loc,
4301 Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref),
4302 Selector_Name => Make_Identifier (Loc, Name_Prev))));
4305 Make_Defining_Identifier (Loc,
4306 Chars => New_Internal_Name ('C'));
4309 Make_Object_Declaration (Loc,
4310 Defining_Identifier => Next_Tmp,
4312 Object_Definition =>
4313 New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
4316 Make_Selected_Component (Loc,
4318 Unchecked_Convert_To (RTE (RE_Finalizable),
4319 New_Copy_Tree (Ctrl_Ref)),
4320 Selector_Name => Make_Identifier (Loc, Name_Next))));
4322 -- Do the Assignment
4324 Append_To (Res, Relocate_Node (N));
4327 -- Regular (non VM) processing for controlled types and types with
4328 -- controlled components
4330 -- Variables of such types contain pointers used to chain them in
4331 -- finalization lists, in addition to user data. These pointers
4332 -- are specific to each object of the type, not to the value being
4335 -- Thus they need to be left intact during the assignment. We
4336 -- achieve this by constructing a Storage_Array subtype, and by
4337 -- overlaying objects of this type on the source and target of the
4338 -- assignment. The assignment is then rewritten to assignments of
4339 -- slices of these arrays, copying the user data, and leaving the
4340 -- pointers untouched.
4342 Controlled_Actions : declare
4344 -- A reference to the Prev component of the record controller
4346 First_After_Root : Node_Id := Empty;
4347 -- Index of first byte to be copied (used to skip
4348 -- Root_Controlled in controlled objects).
4350 Last_Before_Hole : Node_Id := Empty;
4351 -- Index of last byte to be copied before outermost record
4354 Hole_Length : Node_Id := Empty;
4355 -- Length of record controller data (Prev and Next pointers)
4357 First_After_Hole : Node_Id := Empty;
4358 -- Index of first byte to be copied after outermost record
4361 Expr, Source_Size : Node_Id;
4362 Source_Actual_Subtype : Entity_Id;
4363 -- Used for computation of the size of the data to be copied
4365 Range_Type : Entity_Id;
4366 Opaque_Type : Entity_Id;
4368 function Build_Slice
4371 Hi : Node_Id) return Node_Id;
4372 -- Build and return a slice of an array of type S overlaid on
4373 -- object Rec, with bounds specified by Lo and Hi. If either
4374 -- bound is empty, a default of S'First (respectively S'Last)
4381 function Build_Slice
4384 Hi : Node_Id) return Node_Id
4389 Opaque : constant Node_Id :=
4390 Unchecked_Convert_To (Opaque_Type,
4391 Make_Attribute_Reference (Loc,
4393 Attribute_Name => Name_Address));
4394 -- Access value designating an opaque storage array of type
4395 -- S overlaid on record Rec.
4398 -- Compute slice bounds using S'First (1) and S'Last as
4399 -- default values when not specified by the caller.
4402 Lo_Bound := Make_Integer_Literal (Loc, 1);
4408 Hi_Bound := Make_Attribute_Reference (Loc,
4409 Prefix => New_Occurrence_Of (Range_Type, Loc),
4410 Attribute_Name => Name_Last);
4415 return Make_Slice (Loc,
4418 Discrete_Range => Make_Range (Loc,
4419 Lo_Bound, Hi_Bound));
4422 -- Start of processing for Controlled_Actions
4425 -- Create a constrained subtype of Storage_Array whose size
4426 -- corresponds to the value being assigned.
4428 -- subtype G is Storage_Offset range
4429 -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit
4431 Expr := Duplicate_Subexpr_No_Checks (Expression (N));
4433 if Nkind (Expr) = N_Qualified_Expression then
4434 Expr := Expression (Expr);
4437 Source_Actual_Subtype := Etype (Expr);
4439 if Has_Discriminants (Source_Actual_Subtype)
4440 and then not Is_Constrained (Source_Actual_Subtype)
4443 Build_Actual_Subtype (Source_Actual_Subtype, Expr));
4444 Source_Actual_Subtype := Defining_Identifier (Last (Res));
4450 Make_Attribute_Reference (Loc,
4452 New_Occurrence_Of (Source_Actual_Subtype, Loc),
4453 Attribute_Name => Name_Size),
4455 Make_Integer_Literal (Loc,
4456 Intval => System_Storage_Unit - 1));
4459 Make_Op_Divide (Loc,
4460 Left_Opnd => Source_Size,
4462 Make_Integer_Literal (Loc,
4463 Intval => System_Storage_Unit));
4466 Make_Defining_Identifier (Loc,
4467 New_Internal_Name ('G'));
4470 Make_Subtype_Declaration (Loc,
4471 Defining_Identifier => Range_Type,
4472 Subtype_Indication =>
4473 Make_Subtype_Indication (Loc,
4475 New_Reference_To (RTE (RE_Storage_Offset), Loc),
4476 Constraint => Make_Range_Constraint (Loc,
4479 Low_Bound => Make_Integer_Literal (Loc, 1),
4480 High_Bound => Source_Size)))));
4482 -- subtype S is Storage_Array (G)
4485 Make_Subtype_Declaration (Loc,
4486 Defining_Identifier =>
4487 Make_Defining_Identifier (Loc,
4488 New_Internal_Name ('S')),
4489 Subtype_Indication =>
4490 Make_Subtype_Indication (Loc,
4492 New_Reference_To (RTE (RE_Storage_Array), Loc),
4494 Make_Index_Or_Discriminant_Constraint (Loc,
4496 New_List (New_Reference_To (Range_Type, Loc))))));
4498 -- type A is access S
4501 Make_Defining_Identifier (Loc,
4502 Chars => New_Internal_Name ('A'));
4505 Make_Full_Type_Declaration (Loc,
4506 Defining_Identifier => Opaque_Type,
4508 Make_Access_To_Object_Definition (Loc,
4509 Subtype_Indication =>
4511 Defining_Identifier (Last (Res)), Loc))));
4513 -- Generate appropriate slice assignments
4515 First_After_Root := Make_Integer_Literal (Loc, 1);
4517 -- For the case of a controlled object, skip the
4518 -- Root_Controlled part.
4520 if Is_Controlled (T) then
4524 Make_Op_Divide (Loc,
4525 Make_Attribute_Reference (Loc,
4527 New_Occurrence_Of (RTE (RE_Root_Controlled), Loc),
4528 Attribute_Name => Name_Size),
4529 Make_Integer_Literal (Loc, System_Storage_Unit)));
4532 -- For the case of a record with controlled components, skip
4533 -- the Prev and Next components of the record controller.
4534 -- These components constitute a 'hole' in the middle of the
4535 -- data to be copied.
4537 if Has_Controlled_Component (T) then
4539 Make_Selected_Component (Loc,
4541 Make_Selected_Component (Loc,
4542 Prefix => Duplicate_Subexpr_No_Checks (L),
4544 New_Reference_To (Controller_Component (T), Loc)),
4545 Selector_Name => Make_Identifier (Loc, Name_Prev));
4547 -- Last index before hole: determined by position of
4548 -- the _Controller.Prev component.
4551 Make_Defining_Identifier (Loc,
4552 New_Internal_Name ('L'));
4555 Make_Object_Declaration (Loc,
4556 Defining_Identifier => Last_Before_Hole,
4557 Object_Definition => New_Occurrence_Of (
4558 RTE (RE_Storage_Offset), Loc),
4559 Constant_Present => True,
4560 Expression => Make_Op_Add (Loc,
4561 Make_Attribute_Reference (Loc,
4563 Attribute_Name => Name_Position),
4564 Make_Attribute_Reference (Loc,
4565 Prefix => New_Copy_Tree (Prefix (Prev_Ref)),
4566 Attribute_Name => Name_Position))));
4568 -- Hole length: size of the Prev and Next components
4571 Make_Op_Multiply (Loc,
4572 Left_Opnd => Make_Integer_Literal (Loc, Uint_2),
4574 Make_Op_Divide (Loc,
4576 Make_Attribute_Reference (Loc,
4577 Prefix => New_Copy_Tree (Prev_Ref),
4578 Attribute_Name => Name_Size),
4580 Make_Integer_Literal (Loc,
4581 Intval => System_Storage_Unit)));
4583 -- First index after hole
4586 Make_Defining_Identifier (Loc,
4587 New_Internal_Name ('F'));
4590 Make_Object_Declaration (Loc,
4591 Defining_Identifier => First_After_Hole,
4592 Object_Definition => New_Occurrence_Of (
4593 RTE (RE_Storage_Offset), Loc),
4594 Constant_Present => True,
4600 New_Occurrence_Of (Last_Before_Hole, Loc),
4601 Right_Opnd => Hole_Length),
4602 Right_Opnd => Make_Integer_Literal (Loc, 1))));
4605 New_Occurrence_Of (Last_Before_Hole, Loc);
4607 New_Occurrence_Of (First_After_Hole, Loc);
4610 -- Assign the first slice (possibly skipping Root_Controlled,
4611 -- up to the beginning of the record controller if present,
4612 -- up to the end of the object if not).
4614 Append_To (Res, Make_Assignment_Statement (Loc,
4615 Name => Build_Slice (
4616 Rec => Duplicate_Subexpr_No_Checks (L),
4617 Lo => First_After_Root,
4618 Hi => Last_Before_Hole),
4620 Expression => Build_Slice (
4621 Rec => Expression (N),
4622 Lo => First_After_Root,
4623 Hi => New_Copy_Tree (Last_Before_Hole))));
4625 if Present (First_After_Hole) then
4627 -- If a record controller is present, copy the second slice,
4628 -- from right after the _Controller.Next component up to the
4629 -- end of the object.
4631 Append_To (Res, Make_Assignment_Statement (Loc,
4632 Name => Build_Slice (
4633 Rec => Duplicate_Subexpr_No_Checks (L),
4634 Lo => First_After_Hole,
4636 Expression => Build_Slice (
4637 Rec => Duplicate_Subexpr_No_Checks (Expression (N)),
4638 Lo => New_Copy_Tree (First_After_Hole),
4641 end Controlled_Actions;
4645 Append_To (Res, Relocate_Node (N));
4652 Make_Assignment_Statement (Loc,
4654 Make_Selected_Component (Loc,
4655 Prefix => Duplicate_Subexpr_No_Checks (L),
4656 Selector_Name => New_Reference_To (First_Tag_Component (T),
4658 Expression => New_Reference_To (Tag_Tmp, Loc)));
4662 if VM_Target /= No_VM then
4663 -- Restore the finalization pointers
4666 Make_Assignment_Statement (Loc,
4668 Make_Selected_Component (Loc,
4670 Unchecked_Convert_To (RTE (RE_Finalizable),
4671 New_Copy_Tree (Ctrl_Ref)),
4672 Selector_Name => Make_Identifier (Loc, Name_Prev)),
4673 Expression => New_Reference_To (Prev_Tmp, Loc)));
4676 Make_Assignment_Statement (Loc,
4678 Make_Selected_Component (Loc,
4680 Unchecked_Convert_To (RTE (RE_Finalizable),
4681 New_Copy_Tree (Ctrl_Ref)),
4682 Selector_Name => Make_Identifier (Loc, Name_Next)),
4683 Expression => New_Reference_To (Next_Tmp, Loc)));
4686 -- Adjust the target after the assignment when controlled (not in the
4687 -- init proc since it is an initialization more than an assignment).
4689 Append_List_To (Res,
4691 Ref => Duplicate_Subexpr_Move_Checks (L),
4693 Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc),
4694 With_Attach => Make_Integer_Literal (Loc, 0)));
4700 -- Could use comment here ???
4702 when RE_Not_Available =>
4704 end Make_Tag_Ctrl_Assignment;