1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree
; use Atree
;
27 with Checks
; use Checks
;
28 with Debug
; use Debug
;
29 with Einfo
; use Einfo
;
30 with Elists
; use Elists
;
31 with Exp_Atag
; use Exp_Atag
;
32 with Exp_Aggr
; use Exp_Aggr
;
33 with Exp_Ch6
; use Exp_Ch6
;
34 with Exp_Ch7
; use Exp_Ch7
;
35 with Exp_Ch11
; use Exp_Ch11
;
36 with Exp_Dbug
; use Exp_Dbug
;
37 with Exp_Pakd
; use Exp_Pakd
;
38 with Exp_Tss
; use Exp_Tss
;
39 with Exp_Util
; use Exp_Util
;
40 with Namet
; use Namet
;
41 with Nlists
; use Nlists
;
42 with Nmake
; use Nmake
;
44 with Restrict
; use Restrict
;
45 with Rident
; use Rident
;
46 with Rtsfind
; use Rtsfind
;
47 with Sinfo
; use Sinfo
;
49 with Sem_Aux
; use Sem_Aux
;
50 with Sem_Ch3
; use Sem_Ch3
;
51 with Sem_Ch8
; use Sem_Ch8
;
52 with Sem_Ch13
; use Sem_Ch13
;
53 with Sem_Eval
; use Sem_Eval
;
54 with Sem_Res
; use Sem_Res
;
55 with Sem_Util
; use Sem_Util
;
56 with Snames
; use Snames
;
57 with Stand
; use Stand
;
58 with Stringt
; use Stringt
;
59 with Targparm
; use Targparm
;
60 with Tbuild
; use Tbuild
;
61 with Ttypes
; use Ttypes
;
62 with Uintp
; use Uintp
;
63 with Validsw
; use Validsw
;
65 package body Exp_Ch5
is
67 function Change_Of_Representation
(N
: Node_Id
) return Boolean;
68 -- Determine if the right hand side of the assignment N is a type
69 -- conversion which requires a change of representation. Called
70 -- only for the array and record cases.
72 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
);
73 -- N is an assignment which assigns an array value. This routine process
74 -- the various special cases and checks required for such assignments,
75 -- including change of representation. Rhs is normally simply the right
76 -- hand side of the assignment, except that if the right hand side is
77 -- a type conversion or a qualified expression, then the Rhs is the
78 -- actual expression inside any such type conversions or qualifications.
80 function Expand_Assign_Array_Loop
87 Rev
: Boolean) return Node_Id
;
88 -- N is an assignment statement which assigns an array value. This routine
89 -- expands the assignment into a loop (or nested loops for the case of a
90 -- multi-dimensional array) to do the assignment component by component.
91 -- Larray and Rarray are the entities of the actual arrays on the left
92 -- hand and right hand sides. L_Type and R_Type are the types of these
93 -- arrays (which may not be the same, due to either sliding, or to a
94 -- change of representation case). Ndim is the number of dimensions and
95 -- the parameter Rev indicates if the loops run normally (Rev = False),
96 -- or reversed (Rev = True). The value returned is the constructed
97 -- loop statement. Auxiliary declarations are inserted before node N
98 -- using the standard Insert_Actions mechanism.
100 procedure Expand_Assign_Record
(N
: Node_Id
);
101 -- N is an assignment of a non-tagged record value. This routine handles
102 -- the case where the assignment must be made component by component,
103 -- either because the target is not byte aligned, or there is a change
104 -- of representation, or when we have a tagged type with a representation
105 -- clause (this last case is required because holes in the tagged type
106 -- might be filled with components from child types).
108 procedure Expand_Non_Function_Return
(N
: Node_Id
);
109 -- Called by Expand_N_Simple_Return_Statement in case we're returning from
110 -- a procedure body, entry body, accept statement, or extended return
111 -- statement. Note that all non-function returns are simple return
114 procedure Expand_Simple_Function_Return
(N
: Node_Id
);
115 -- Expand simple return from function. In the case where we are returning
116 -- from a function body this is called by Expand_N_Simple_Return_Statement.
118 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
;
119 -- Generate the necessary code for controlled and tagged assignment, that
120 -- is to say, finalization of the target before, adjustment of the target
121 -- after and save and restore of the tag and finalization pointers which
122 -- are not 'part of the value' and must not be changed upon assignment. N
123 -- is the original Assignment node.
125 ------------------------------
126 -- Change_Of_Representation --
127 ------------------------------
129 function Change_Of_Representation
(N
: Node_Id
) return Boolean is
130 Rhs
: constant Node_Id
:= Expression
(N
);
133 Nkind
(Rhs
) = N_Type_Conversion
135 not Same_Representation
(Etype
(Rhs
), Etype
(Expression
(Rhs
)));
136 end Change_Of_Representation
;
138 -------------------------
139 -- Expand_Assign_Array --
140 -------------------------
142 -- There are two issues here. First, do we let Gigi do a block move, or
143 -- do we expand out into a loop? Second, we need to set the two flags
144 -- Forwards_OK and Backwards_OK which show whether the block move (or
145 -- corresponding loops) can be legitimately done in a forwards (low to
146 -- high) or backwards (high to low) manner.
148 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
) is
149 Loc
: constant Source_Ptr
:= Sloc
(N
);
151 Lhs
: constant Node_Id
:= Name
(N
);
153 Act_Lhs
: constant Node_Id
:= Get_Referenced_Object
(Lhs
);
154 Act_Rhs
: Node_Id
:= Get_Referenced_Object
(Rhs
);
156 L_Type
: constant Entity_Id
:=
157 Underlying_Type
(Get_Actual_Subtype
(Act_Lhs
));
158 R_Type
: Entity_Id
:=
159 Underlying_Type
(Get_Actual_Subtype
(Act_Rhs
));
161 L_Slice
: constant Boolean := Nkind
(Act_Lhs
) = N_Slice
;
162 R_Slice
: constant Boolean := Nkind
(Act_Rhs
) = N_Slice
;
164 Crep
: constant Boolean := Change_Of_Representation
(N
);
169 Ndim
: constant Pos
:= Number_Dimensions
(L_Type
);
171 Loop_Required
: Boolean := False;
172 -- This switch is set to True if the array move must be done using
173 -- an explicit front end generated loop.
175 procedure Apply_Dereference
(Arg
: Node_Id
);
176 -- If the argument is an access to an array, and the assignment is
177 -- converted into a procedure call, apply explicit dereference.
179 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean;
180 -- Test if Exp is a reference to an array whose declaration has
181 -- an address clause, or it is a slice of such an array.
183 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean;
184 -- Test if Exp is a reference to an array which is either a formal
185 -- parameter or a slice of a formal parameter. These are the cases
186 -- where hidden aliasing can occur.
188 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean;
189 -- Determine if Exp is a reference to an array variable which is other
190 -- than an object defined in the current scope, or a slice of such
191 -- an object. Such objects can be aliased to parameters (unlike local
192 -- array references).
194 -----------------------
195 -- Apply_Dereference --
196 -----------------------
198 procedure Apply_Dereference
(Arg
: Node_Id
) is
199 Typ
: constant Entity_Id
:= Etype
(Arg
);
201 if Is_Access_Type
(Typ
) then
202 Rewrite
(Arg
, Make_Explicit_Dereference
(Loc
,
203 Prefix
=> Relocate_Node
(Arg
)));
204 Analyze_And_Resolve
(Arg
, Designated_Type
(Typ
));
206 end Apply_Dereference
;
208 ------------------------
209 -- Has_Address_Clause --
210 ------------------------
212 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean is
215 (Is_Entity_Name
(Exp
) and then
216 Present
(Address_Clause
(Entity
(Exp
))))
218 (Nkind
(Exp
) = N_Slice
and then Has_Address_Clause
(Prefix
(Exp
)));
219 end Has_Address_Clause
;
221 ---------------------
222 -- Is_Formal_Array --
223 ---------------------
225 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean is
228 (Is_Entity_Name
(Exp
) and then Is_Formal
(Entity
(Exp
)))
230 (Nkind
(Exp
) = N_Slice
and then Is_Formal_Array
(Prefix
(Exp
)));
233 ------------------------
234 -- Is_Non_Local_Array --
235 ------------------------
237 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean is
239 return (Is_Entity_Name
(Exp
)
240 and then Scope
(Entity
(Exp
)) /= Current_Scope
)
241 or else (Nkind
(Exp
) = N_Slice
242 and then Is_Non_Local_Array
(Prefix
(Exp
)));
243 end Is_Non_Local_Array
;
245 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
247 Lhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Lhs
);
248 Rhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Rhs
);
250 Lhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Lhs
);
251 Rhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Rhs
);
253 -- Start of processing for Expand_Assign_Array
256 -- Deal with length check. Note that the length check is done with
257 -- respect to the right hand side as given, not a possible underlying
258 -- renamed object, since this would generate incorrect extra checks.
260 Apply_Length_Check
(Rhs
, L_Type
);
262 -- We start by assuming that the move can be done in either direction,
263 -- i.e. that the two sides are completely disjoint.
265 Set_Forwards_OK
(N
, True);
266 Set_Backwards_OK
(N
, True);
268 -- Normally it is only the slice case that can lead to overlap, and
269 -- explicit checks for slices are made below. But there is one case
270 -- where the slice can be implicit and invisible to us: when we have a
271 -- one dimensional array, and either both operands are parameters, or
272 -- one is a parameter (which can be a slice passed by reference) and the
273 -- other is a non-local variable. In this case the parameter could be a
274 -- slice that overlaps with the other operand.
276 -- However, if the array subtype is a constrained first subtype in the
277 -- parameter case, then we don't have to worry about overlap, since
278 -- slice assignments aren't possible (other than for a slice denoting
281 -- Note: No overlap is possible if there is a change of representation,
282 -- so we can exclude this case.
287 ((Lhs_Formal
and Rhs_Formal
)
289 (Lhs_Formal
and Rhs_Non_Local_Var
)
291 (Rhs_Formal
and Lhs_Non_Local_Var
))
293 (not Is_Constrained
(Etype
(Lhs
))
294 or else not Is_First_Subtype
(Etype
(Lhs
)))
296 -- In the case of compiling for the Java or .NET Virtual Machine,
297 -- slices are always passed by making a copy, so we don't have to
298 -- worry about overlap. We also want to prevent generation of "<"
299 -- comparisons for array addresses, since that's a meaningless
300 -- operation on the VM.
302 and then VM_Target
= No_VM
304 Set_Forwards_OK
(N
, False);
305 Set_Backwards_OK
(N
, False);
307 -- Note: the bit-packed case is not worrisome here, since if we have
308 -- a slice passed as a parameter, it is always aligned on a byte
309 -- boundary, and if there are no explicit slices, the assignment
310 -- can be performed directly.
313 -- If either operand has an address clause clear Backwards_OK and
314 -- Forwards_OK, since we cannot tell if the operands overlap. We
315 -- exclude this treatment when Rhs is an aggregate, since we know
316 -- that overlap can't occur.
318 if (Has_Address_Clause
(Lhs
) and then Nkind
(Rhs
) /= N_Aggregate
)
319 or else Has_Address_Clause
(Rhs
)
321 Set_Forwards_OK
(N
, False);
322 Set_Backwards_OK
(N
, False);
325 -- We certainly must use a loop for change of representation and also
326 -- we use the operand of the conversion on the right hand side as the
327 -- effective right hand side (the component types must match in this
331 Act_Rhs
:= Get_Referenced_Object
(Rhs
);
332 R_Type
:= Get_Actual_Subtype
(Act_Rhs
);
333 Loop_Required
:= True;
335 -- We require a loop if the left side is possibly bit unaligned
337 elsif Possible_Bit_Aligned_Component
(Lhs
)
339 Possible_Bit_Aligned_Component
(Rhs
)
341 Loop_Required
:= True;
343 -- Arrays with controlled components are expanded into a loop to force
344 -- calls to Adjust at the component level.
346 elsif Has_Controlled_Component
(L_Type
) then
347 Loop_Required
:= True;
349 -- If object is atomic, we cannot tolerate a loop
351 elsif Is_Atomic_Object
(Act_Lhs
)
353 Is_Atomic_Object
(Act_Rhs
)
357 -- Loop is required if we have atomic components since we have to
358 -- be sure to do any accesses on an element by element basis.
360 elsif Has_Atomic_Components
(L_Type
)
361 or else Has_Atomic_Components
(R_Type
)
362 or else Is_Atomic
(Component_Type
(L_Type
))
363 or else Is_Atomic
(Component_Type
(R_Type
))
365 Loop_Required
:= True;
367 -- Case where no slice is involved
369 elsif not L_Slice
and not R_Slice
then
371 -- The following code deals with the case of unconstrained bit packed
372 -- arrays. The problem is that the template for such arrays contains
373 -- the bounds of the actual source level array, but the copy of an
374 -- entire array requires the bounds of the underlying array. It would
375 -- be nice if the back end could take care of this, but right now it
376 -- does not know how, so if we have such a type, then we expand out
377 -- into a loop, which is inefficient but works correctly. If we don't
378 -- do this, we get the wrong length computed for the array to be
379 -- moved. The two cases we need to worry about are:
381 -- Explicit dereference of an unconstrained packed array type as in
382 -- the following example:
385 -- type BITS is array(INTEGER range <>) of BOOLEAN;
386 -- pragma PACK(BITS);
387 -- type A is access BITS;
390 -- P1 := new BITS (1 .. 65_535);
391 -- P2 := new BITS (1 .. 65_535);
395 -- A formal parameter reference with an unconstrained bit array type
396 -- is the other case we need to worry about (here we assume the same
397 -- BITS type declared above):
399 -- procedure Write_All (File : out BITS; Contents : BITS);
401 -- File.Storage := Contents;
404 -- We expand to a loop in either of these two cases
406 -- Question for future thought. Another potentially more efficient
407 -- approach would be to create the actual subtype, and then do an
408 -- unchecked conversion to this actual subtype ???
410 Check_Unconstrained_Bit_Packed_Array
: declare
412 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean;
413 -- Function to perform required test for the first case, above
414 -- (dereference of an unconstrained bit packed array).
416 -----------------------
417 -- Is_UBPA_Reference --
418 -----------------------
420 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean is
421 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Opnd
));
423 Des_Type
: Entity_Id
;
426 if Present
(Packed_Array_Type
(Typ
))
427 and then Is_Array_Type
(Packed_Array_Type
(Typ
))
428 and then not Is_Constrained
(Packed_Array_Type
(Typ
))
432 elsif Nkind
(Opnd
) = N_Explicit_Dereference
then
433 P_Type
:= Underlying_Type
(Etype
(Prefix
(Opnd
)));
435 if not Is_Access_Type
(P_Type
) then
439 Des_Type
:= Designated_Type
(P_Type
);
441 Is_Bit_Packed_Array
(Des_Type
)
442 and then not Is_Constrained
(Des_Type
);
448 end Is_UBPA_Reference
;
450 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
453 if Is_UBPA_Reference
(Lhs
)
455 Is_UBPA_Reference
(Rhs
)
457 Loop_Required
:= True;
459 -- Here if we do not have the case of a reference to a bit packed
460 -- unconstrained array case. In this case gigi can most certainly
461 -- handle the assignment if a forwards move is allowed.
463 -- (could it handle the backwards case also???)
465 elsif Forwards_OK
(N
) then
468 end Check_Unconstrained_Bit_Packed_Array
;
470 -- The back end can always handle the assignment if the right side is a
471 -- string literal (note that overlap is definitely impossible in this
472 -- case). If the type is packed, a string literal is always converted
473 -- into an aggregate, except in the case of a null slice, for which no
474 -- aggregate can be written. In that case, rewrite the assignment as a
475 -- null statement, a length check has already been emitted to verify
476 -- that the range of the left-hand side is empty.
478 -- Note that this code is not executed if we have an assignment of a
479 -- string literal to a non-bit aligned component of a record, a case
480 -- which cannot be handled by the backend.
482 elsif Nkind
(Rhs
) = N_String_Literal
then
483 if String_Length
(Strval
(Rhs
)) = 0
484 and then Is_Bit_Packed_Array
(L_Type
)
486 Rewrite
(N
, Make_Null_Statement
(Loc
));
492 -- If either operand is bit packed, then we need a loop, since we can't
493 -- be sure that the slice is byte aligned. Similarly, if either operand
494 -- is a possibly unaligned slice, then we need a loop (since the back
495 -- end cannot handle unaligned slices).
497 elsif Is_Bit_Packed_Array
(L_Type
)
498 or else Is_Bit_Packed_Array
(R_Type
)
499 or else Is_Possibly_Unaligned_Slice
(Lhs
)
500 or else Is_Possibly_Unaligned_Slice
(Rhs
)
502 Loop_Required
:= True;
504 -- If we are not bit-packed, and we have only one slice, then no overlap
505 -- is possible except in the parameter case, so we can let the back end
508 elsif not (L_Slice
and R_Slice
) then
509 if Forwards_OK
(N
) then
514 -- If the right-hand side is a string literal, introduce a temporary for
515 -- it, for use in the generated loop that will follow.
517 if Nkind
(Rhs
) = N_String_Literal
then
519 Temp
: constant Entity_Id
:=
520 Make_Defining_Identifier
(Loc
, New_Internal_Name
('T'));
525 Make_Object_Declaration
(Loc
,
526 Defining_Identifier
=> Temp
,
527 Object_Definition
=> New_Occurrence_Of
(L_Type
, Loc
),
528 Expression
=> Relocate_Node
(Rhs
));
530 Insert_Action
(N
, Decl
);
531 Rewrite
(Rhs
, New_Occurrence_Of
(Temp
, Loc
));
532 R_Type
:= Etype
(Temp
);
536 -- Come here to complete the analysis
538 -- Loop_Required: Set to True if we know that a loop is required
539 -- regardless of overlap considerations.
541 -- Forwards_OK: Set to False if we already know that a forwards
542 -- move is not safe, else set to True.
544 -- Backwards_OK: Set to False if we already know that a backwards
545 -- move is not safe, else set to True
547 -- Our task at this stage is to complete the overlap analysis, which can
548 -- result in possibly setting Forwards_OK or Backwards_OK to False, and
549 -- then generating the final code, either by deciding that it is OK
550 -- after all to let Gigi handle it, or by generating appropriate code
554 L_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(L_Type
));
555 R_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(R_Type
));
557 Left_Lo
: constant Node_Id
:= Type_Low_Bound
(L_Index_Typ
);
558 Left_Hi
: constant Node_Id
:= Type_High_Bound
(L_Index_Typ
);
559 Right_Lo
: constant Node_Id
:= Type_Low_Bound
(R_Index_Typ
);
560 Right_Hi
: constant Node_Id
:= Type_High_Bound
(R_Index_Typ
);
562 Act_L_Array
: Node_Id
;
563 Act_R_Array
: Node_Id
;
569 Cresult
: Compare_Result
;
572 -- Get the expressions for the arrays. If we are dealing with a
573 -- private type, then convert to the underlying type. We can do
574 -- direct assignments to an array that is a private type, but we
575 -- cannot assign to elements of the array without this extra
576 -- unchecked conversion.
578 if Nkind
(Act_Lhs
) = N_Slice
then
579 Larray
:= Prefix
(Act_Lhs
);
583 if Is_Private_Type
(Etype
(Larray
)) then
586 (Underlying_Type
(Etype
(Larray
)), Larray
);
590 if Nkind
(Act_Rhs
) = N_Slice
then
591 Rarray
:= Prefix
(Act_Rhs
);
595 if Is_Private_Type
(Etype
(Rarray
)) then
598 (Underlying_Type
(Etype
(Rarray
)), Rarray
);
602 -- If both sides are slices, we must figure out whether it is safe
603 -- to do the move in one direction or the other. It is always safe
604 -- if there is a change of representation since obviously two arrays
605 -- with different representations cannot possibly overlap.
607 if (not Crep
) and L_Slice
and R_Slice
then
608 Act_L_Array
:= Get_Referenced_Object
(Prefix
(Act_Lhs
));
609 Act_R_Array
:= Get_Referenced_Object
(Prefix
(Act_Rhs
));
611 -- If both left and right hand arrays are entity names, and refer
612 -- to different entities, then we know that the move is safe (the
613 -- two storage areas are completely disjoint).
615 if Is_Entity_Name
(Act_L_Array
)
616 and then Is_Entity_Name
(Act_R_Array
)
617 and then Entity
(Act_L_Array
) /= Entity
(Act_R_Array
)
621 -- Otherwise, we assume the worst, which is that the two arrays
622 -- are the same array. There is no need to check if we know that
623 -- is the case, because if we don't know it, we still have to
626 -- Generally if the same array is involved, then we have an
627 -- overlapping case. We will have to really assume the worst (i.e.
628 -- set neither of the OK flags) unless we can determine the lower
629 -- or upper bounds at compile time and compare them.
634 (Left_Lo
, Right_Lo
, Assume_Valid
=> True);
636 if Cresult
= Unknown
then
639 (Left_Hi
, Right_Hi
, Assume_Valid
=> True);
643 when LT | LE | EQ
=> Set_Backwards_OK
(N
, False);
644 when GT | GE
=> Set_Forwards_OK
(N
, False);
645 when NE | Unknown
=> Set_Backwards_OK
(N
, False);
646 Set_Forwards_OK
(N
, False);
651 -- If after that analysis Loop_Required is False, meaning that we
652 -- have not discovered some non-overlap reason for requiring a loop,
653 -- then the outcome depends on the capabilities of the back end.
655 if not Loop_Required
then
657 -- The GCC back end can deal with all cases of overlap by falling
658 -- back to memmove if it cannot use a more efficient approach.
660 if VM_Target
= No_VM
and not AAMP_On_Target
then
663 -- Assume other back ends can handle it if Forwards_OK is set
665 elsif Forwards_OK
(N
) then
668 -- If Forwards_OK is not set, the back end will need something
669 -- like memmove to handle the move. For now, this processing is
670 -- activated using the .s debug flag (-gnatd.s).
672 elsif Debug_Flag_Dot_S
then
677 -- At this stage we have to generate an explicit loop, and we have
678 -- the following cases:
680 -- Forwards_OK = True
682 -- Rnn : right_index := right_index'First;
683 -- for Lnn in left-index loop
684 -- left (Lnn) := right (Rnn);
685 -- Rnn := right_index'Succ (Rnn);
688 -- Note: the above code MUST be analyzed with checks off, because
689 -- otherwise the Succ could overflow. But in any case this is more
692 -- Forwards_OK = False, Backwards_OK = True
694 -- Rnn : right_index := right_index'Last;
695 -- for Lnn in reverse left-index loop
696 -- left (Lnn) := right (Rnn);
697 -- Rnn := right_index'Pred (Rnn);
700 -- Note: the above code MUST be analyzed with checks off, because
701 -- otherwise the Pred could overflow. But in any case this is more
704 -- Forwards_OK = Backwards_OK = False
706 -- This only happens if we have the same array on each side. It is
707 -- possible to create situations using overlays that violate this,
708 -- but we simply do not promise to get this "right" in this case.
710 -- There are two possible subcases. If the No_Implicit_Conditionals
711 -- restriction is set, then we generate the following code:
714 -- T : constant <operand-type> := rhs;
719 -- If implicit conditionals are permitted, then we generate:
721 -- if Left_Lo <= Right_Lo then
722 -- <code for Forwards_OK = True above>
724 -- <code for Backwards_OK = True above>
727 -- In order to detect possible aliasing, we examine the renamed
728 -- expression when the source or target is a renaming. However,
729 -- the renaming may be intended to capture an address that may be
730 -- affected by subsequent code, and therefore we must recover
731 -- the actual entity for the expansion that follows, not the
732 -- object it renames. In particular, if source or target designate
733 -- a portion of a dynamically allocated object, the pointer to it
734 -- may be reassigned but the renaming preserves the proper location.
736 if Is_Entity_Name
(Rhs
)
738 Nkind
(Parent
(Entity
(Rhs
))) = N_Object_Renaming_Declaration
739 and then Nkind
(Act_Rhs
) = N_Slice
744 if Is_Entity_Name
(Lhs
)
746 Nkind
(Parent
(Entity
(Lhs
))) = N_Object_Renaming_Declaration
747 and then Nkind
(Act_Lhs
) = N_Slice
752 -- Cases where either Forwards_OK or Backwards_OK is true
754 if Forwards_OK
(N
) or else Backwards_OK
(N
) then
755 if Needs_Finalization
(Component_Type
(L_Type
))
756 and then Base_Type
(L_Type
) = Base_Type
(R_Type
)
758 and then not No_Ctrl_Actions
(N
)
761 Proc
: constant Entity_Id
:=
762 TSS
(Base_Type
(L_Type
), TSS_Slice_Assign
);
766 Apply_Dereference
(Larray
);
767 Apply_Dereference
(Rarray
);
768 Actuals
:= New_List
(
769 Duplicate_Subexpr
(Larray
, Name_Req
=> True),
770 Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
771 Duplicate_Subexpr
(Left_Lo
, Name_Req
=> True),
772 Duplicate_Subexpr
(Left_Hi
, Name_Req
=> True),
773 Duplicate_Subexpr
(Right_Lo
, Name_Req
=> True),
774 Duplicate_Subexpr
(Right_Hi
, Name_Req
=> True));
778 Boolean_Literals
(not Forwards_OK
(N
)), Loc
));
781 Make_Procedure_Call_Statement
(Loc
,
782 Name
=> New_Reference_To
(Proc
, Loc
),
783 Parameter_Associations
=> Actuals
));
788 Expand_Assign_Array_Loop
789 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
790 Rev
=> not Forwards_OK
(N
)));
793 -- Case of both are false with No_Implicit_Conditionals
795 elsif Restriction_Active
(No_Implicit_Conditionals
) then
797 T
: constant Entity_Id
:=
798 Make_Defining_Identifier
(Loc
, Chars
=> Name_T
);
802 Make_Block_Statement
(Loc
,
803 Declarations
=> New_List
(
804 Make_Object_Declaration
(Loc
,
805 Defining_Identifier
=> T
,
806 Constant_Present
=> True,
808 New_Occurrence_Of
(Etype
(Rhs
), Loc
),
809 Expression
=> Relocate_Node
(Rhs
))),
811 Handled_Statement_Sequence
=>
812 Make_Handled_Sequence_Of_Statements
(Loc
,
813 Statements
=> New_List
(
814 Make_Assignment_Statement
(Loc
,
815 Name
=> Relocate_Node
(Lhs
),
816 Expression
=> New_Occurrence_Of
(T
, Loc
))))));
819 -- Case of both are false with implicit conditionals allowed
822 -- Before we generate this code, we must ensure that the left and
823 -- right side array types are defined. They may be itypes, and we
824 -- cannot let them be defined inside the if, since the first use
825 -- in the then may not be executed.
827 Ensure_Defined
(L_Type
, N
);
828 Ensure_Defined
(R_Type
, N
);
830 -- We normally compare addresses to find out which way round to
831 -- do the loop, since this is reliable, and handles the cases of
832 -- parameters, conversions etc. But we can't do that in the bit
833 -- packed case or the VM case, because addresses don't work there.
835 if not Is_Bit_Packed_Array
(L_Type
) and then VM_Target
= No_VM
then
839 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
840 Make_Attribute_Reference
(Loc
,
842 Make_Indexed_Component
(Loc
,
844 Duplicate_Subexpr_Move_Checks
(Larray
, True),
845 Expressions
=> New_List
(
846 Make_Attribute_Reference
(Loc
,
850 Attribute_Name
=> Name_First
))),
851 Attribute_Name
=> Name_Address
)),
854 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
855 Make_Attribute_Reference
(Loc
,
857 Make_Indexed_Component
(Loc
,
859 Duplicate_Subexpr_Move_Checks
(Rarray
, True),
860 Expressions
=> New_List
(
861 Make_Attribute_Reference
(Loc
,
865 Attribute_Name
=> Name_First
))),
866 Attribute_Name
=> Name_Address
)));
868 -- For the bit packed and VM cases we use the bounds. That's OK,
869 -- because we don't have to worry about parameters, since they
870 -- cannot cause overlap. Perhaps we should worry about weird slice
876 Cleft_Lo
:= New_Copy_Tree
(Left_Lo
);
877 Cright_Lo
:= New_Copy_Tree
(Right_Lo
);
879 -- If the types do not match we add an implicit conversion
880 -- here to ensure proper match
882 if Etype
(Left_Lo
) /= Etype
(Right_Lo
) then
884 Unchecked_Convert_To
(Etype
(Left_Lo
), Cright_Lo
);
887 -- Reset the Analyzed flag, because the bounds of the index
888 -- type itself may be universal, and must must be reaanalyzed
889 -- to acquire the proper type for the back end.
891 Set_Analyzed
(Cleft_Lo
, False);
892 Set_Analyzed
(Cright_Lo
, False);
896 Left_Opnd
=> Cleft_Lo
,
897 Right_Opnd
=> Cright_Lo
);
900 if Needs_Finalization
(Component_Type
(L_Type
))
901 and then Base_Type
(L_Type
) = Base_Type
(R_Type
)
903 and then not No_Ctrl_Actions
(N
)
906 -- Call TSS procedure for array assignment, passing the
907 -- explicit bounds of right and left hand sides.
910 Proc
: constant Entity_Id
:=
911 TSS
(Base_Type
(L_Type
), TSS_Slice_Assign
);
915 Apply_Dereference
(Larray
);
916 Apply_Dereference
(Rarray
);
917 Actuals
:= New_List
(
918 Duplicate_Subexpr
(Larray
, Name_Req
=> True),
919 Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
920 Duplicate_Subexpr
(Left_Lo
, Name_Req
=> True),
921 Duplicate_Subexpr
(Left_Hi
, Name_Req
=> True),
922 Duplicate_Subexpr
(Right_Lo
, Name_Req
=> True),
923 Duplicate_Subexpr
(Right_Hi
, Name_Req
=> True));
927 Right_Opnd
=> Condition
));
930 Make_Procedure_Call_Statement
(Loc
,
931 Name
=> New_Reference_To
(Proc
, Loc
),
932 Parameter_Associations
=> Actuals
));
937 Make_Implicit_If_Statement
(N
,
938 Condition
=> Condition
,
940 Then_Statements
=> New_List
(
941 Expand_Assign_Array_Loop
942 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
945 Else_Statements
=> New_List
(
946 Expand_Assign_Array_Loop
947 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
952 Analyze
(N
, Suppress
=> All_Checks
);
956 when RE_Not_Available
=>
958 end Expand_Assign_Array
;
960 ------------------------------
961 -- Expand_Assign_Array_Loop --
962 ------------------------------
964 -- The following is an example of the loop generated for the case of a
965 -- two-dimensional array:
970 -- for L1b in 1 .. 100 loop
974 -- for L3b in 1 .. 100 loop
975 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
976 -- R4b := Tm1X2'succ(R4b);
979 -- R2b := Tm1X1'succ(R2b);
983 -- Here Rev is False, and Tm1Xn are the subscript types for the right hand
984 -- side. The declarations of R2b and R4b are inserted before the original
985 -- assignment statement.
987 function Expand_Assign_Array_Loop
994 Rev
: Boolean) return Node_Id
996 Loc
: constant Source_Ptr
:= Sloc
(N
);
998 Lnn
: array (1 .. Ndim
) of Entity_Id
;
999 Rnn
: array (1 .. Ndim
) of Entity_Id
;
1000 -- Entities used as subscripts on left and right sides
1002 L_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
1003 R_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
1004 -- Left and right index types
1013 F_Or_L
:= Name_Last
;
1014 S_Or_P
:= Name_Pred
;
1016 F_Or_L
:= Name_First
;
1017 S_Or_P
:= Name_Succ
;
1020 -- Setup index types and subscript entities
1027 L_Index
:= First_Index
(L_Type
);
1028 R_Index
:= First_Index
(R_Type
);
1030 for J
in 1 .. Ndim
loop
1032 Make_Defining_Identifier
(Loc
,
1033 Chars
=> New_Internal_Name
('L'));
1036 Make_Defining_Identifier
(Loc
,
1037 Chars
=> New_Internal_Name
('R'));
1039 L_Index_Type
(J
) := Etype
(L_Index
);
1040 R_Index_Type
(J
) := Etype
(R_Index
);
1042 Next_Index
(L_Index
);
1043 Next_Index
(R_Index
);
1047 -- Now construct the assignment statement
1050 ExprL
: constant List_Id
:= New_List
;
1051 ExprR
: constant List_Id
:= New_List
;
1054 for J
in 1 .. Ndim
loop
1055 Append_To
(ExprL
, New_Occurrence_Of
(Lnn
(J
), Loc
));
1056 Append_To
(ExprR
, New_Occurrence_Of
(Rnn
(J
), Loc
));
1060 Make_Assignment_Statement
(Loc
,
1062 Make_Indexed_Component
(Loc
,
1063 Prefix
=> Duplicate_Subexpr
(Larray
, Name_Req
=> True),
1064 Expressions
=> ExprL
),
1066 Make_Indexed_Component
(Loc
,
1067 Prefix
=> Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
1068 Expressions
=> ExprR
));
1070 -- We set assignment OK, since there are some cases, e.g. in object
1071 -- declarations, where we are actually assigning into a constant.
1072 -- If there really is an illegality, it was caught long before now,
1073 -- and was flagged when the original assignment was analyzed.
1075 Set_Assignment_OK
(Name
(Assign
));
1077 -- Propagate the No_Ctrl_Actions flag to individual assignments
1079 Set_No_Ctrl_Actions
(Assign
, No_Ctrl_Actions
(N
));
1082 -- Now construct the loop from the inside out, with the last subscript
1083 -- varying most rapidly. Note that Assign is first the raw assignment
1084 -- statement, and then subsequently the loop that wraps it up.
1086 for J
in reverse 1 .. Ndim
loop
1088 Make_Block_Statement
(Loc
,
1089 Declarations
=> New_List
(
1090 Make_Object_Declaration
(Loc
,
1091 Defining_Identifier
=> Rnn
(J
),
1092 Object_Definition
=>
1093 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1095 Make_Attribute_Reference
(Loc
,
1096 Prefix
=> New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1097 Attribute_Name
=> F_Or_L
))),
1099 Handled_Statement_Sequence
=>
1100 Make_Handled_Sequence_Of_Statements
(Loc
,
1101 Statements
=> New_List
(
1102 Make_Implicit_Loop_Statement
(N
,
1104 Make_Iteration_Scheme
(Loc
,
1105 Loop_Parameter_Specification
=>
1106 Make_Loop_Parameter_Specification
(Loc
,
1107 Defining_Identifier
=> Lnn
(J
),
1108 Reverse_Present
=> Rev
,
1109 Discrete_Subtype_Definition
=>
1110 New_Reference_To
(L_Index_Type
(J
), Loc
))),
1112 Statements
=> New_List
(
1115 Make_Assignment_Statement
(Loc
,
1116 Name
=> New_Occurrence_Of
(Rnn
(J
), Loc
),
1118 Make_Attribute_Reference
(Loc
,
1120 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1121 Attribute_Name
=> S_Or_P
,
1122 Expressions
=> New_List
(
1123 New_Occurrence_Of
(Rnn
(J
), Loc
)))))))));
1127 end Expand_Assign_Array_Loop
;
1129 --------------------------
1130 -- Expand_Assign_Record --
1131 --------------------------
1133 procedure Expand_Assign_Record
(N
: Node_Id
) is
1134 Lhs
: constant Node_Id
:= Name
(N
);
1135 Rhs
: Node_Id
:= Expression
(N
);
1136 L_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Lhs
));
1139 -- If change of representation, then extract the real right hand side
1140 -- from the type conversion, and proceed with component-wise assignment,
1141 -- since the two types are not the same as far as the back end is
1144 if Change_Of_Representation
(N
) then
1145 Rhs
:= Expression
(Rhs
);
1147 -- If this may be a case of a large bit aligned component, then proceed
1148 -- with component-wise assignment, to avoid possible clobbering of other
1149 -- components sharing bits in the first or last byte of the component to
1152 elsif Possible_Bit_Aligned_Component
(Lhs
)
1154 Possible_Bit_Aligned_Component
(Rhs
)
1158 -- If we have a tagged type that has a complete record representation
1159 -- clause, we must do we must do component-wise assignments, since child
1160 -- types may have used gaps for their components, and we might be
1161 -- dealing with a view conversion.
1163 elsif Is_Fully_Repped_Tagged_Type
(L_Typ
) then
1166 -- If neither condition met, then nothing special to do, the back end
1167 -- can handle assignment of the entire component as a single entity.
1173 -- At this stage we know that we must do a component wise assignment
1176 Loc
: constant Source_Ptr
:= Sloc
(N
);
1177 R_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Rhs
));
1178 Decl
: constant Node_Id
:= Declaration_Node
(R_Typ
);
1182 function Find_Component
1184 Comp
: Entity_Id
) return Entity_Id
;
1185 -- Find the component with the given name in the underlying record
1186 -- declaration for Typ. We need to use the actual entity because the
1187 -- type may be private and resolution by identifier alone would fail.
1189 function Make_Component_List_Assign
1191 U_U
: Boolean := False) return List_Id
;
1192 -- Returns a sequence of statements to assign the components that
1193 -- are referenced in the given component list. The flag U_U is
1194 -- used to force the usage of the inferred value of the variant
1195 -- part expression as the switch for the generated case statement.
1197 function Make_Field_Assign
1199 U_U
: Boolean := False) return Node_Id
;
1200 -- Given C, the entity for a discriminant or component, build an
1201 -- assignment for the corresponding field values. The flag U_U
1202 -- signals the presence of an Unchecked_Union and forces the usage
1203 -- of the inferred discriminant value of C as the right hand side
1204 -- of the assignment.
1206 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
;
1207 -- Given CI, a component items list, construct series of statements
1208 -- for fieldwise assignment of the corresponding components.
1210 --------------------
1211 -- Find_Component --
1212 --------------------
1214 function Find_Component
1216 Comp
: Entity_Id
) return Entity_Id
1218 Utyp
: constant Entity_Id
:= Underlying_Type
(Typ
);
1222 C
:= First_Entity
(Utyp
);
1223 while Present
(C
) loop
1224 if Chars
(C
) = Chars
(Comp
) then
1231 raise Program_Error
;
1234 --------------------------------
1235 -- Make_Component_List_Assign --
1236 --------------------------------
1238 function Make_Component_List_Assign
1240 U_U
: Boolean := False) return List_Id
1242 CI
: constant List_Id
:= Component_Items
(CL
);
1243 VP
: constant Node_Id
:= Variant_Part
(CL
);
1253 Result
:= Make_Field_Assigns
(CI
);
1255 if Present
(VP
) then
1256 V
:= First_Non_Pragma
(Variants
(VP
));
1258 while Present
(V
) loop
1260 DC
:= First
(Discrete_Choices
(V
));
1261 while Present
(DC
) loop
1262 Append_To
(DCH
, New_Copy_Tree
(DC
));
1267 Make_Case_Statement_Alternative
(Loc
,
1268 Discrete_Choices
=> DCH
,
1270 Make_Component_List_Assign
(Component_List
(V
))));
1271 Next_Non_Pragma
(V
);
1274 -- If we have an Unchecked_Union, use the value of the inferred
1275 -- discriminant of the variant part expression as the switch
1276 -- for the case statement. The case statement may later be
1281 New_Copy
(Get_Discriminant_Value
(
1284 Discriminant_Constraint
(Etype
(Rhs
))));
1287 Make_Selected_Component
(Loc
,
1288 Prefix
=> Duplicate_Subexpr
(Rhs
),
1290 Make_Identifier
(Loc
, Chars
(Name
(VP
))));
1294 Make_Case_Statement
(Loc
,
1296 Alternatives
=> Alts
));
1300 end Make_Component_List_Assign
;
1302 -----------------------
1303 -- Make_Field_Assign --
1304 -----------------------
1306 function Make_Field_Assign
1308 U_U
: Boolean := False) return Node_Id
1314 -- In the case of an Unchecked_Union, use the discriminant
1315 -- constraint value as on the right hand side of the assignment.
1319 New_Copy
(Get_Discriminant_Value
(C
,
1321 Discriminant_Constraint
(Etype
(Rhs
))));
1324 Make_Selected_Component
(Loc
,
1325 Prefix
=> Duplicate_Subexpr
(Rhs
),
1326 Selector_Name
=> New_Occurrence_Of
(C
, Loc
));
1330 Make_Assignment_Statement
(Loc
,
1332 Make_Selected_Component
(Loc
,
1333 Prefix
=> Duplicate_Subexpr
(Lhs
),
1335 New_Occurrence_Of
(Find_Component
(L_Typ
, C
), Loc
)),
1336 Expression
=> Expr
);
1338 -- Set Assignment_OK, so discriminants can be assigned
1340 Set_Assignment_OK
(Name
(A
), True);
1342 if Componentwise_Assignment
(N
)
1343 and then Nkind
(Name
(A
)) = N_Selected_Component
1344 and then Chars
(Selector_Name
(Name
(A
))) = Name_uParent
1346 Set_Componentwise_Assignment
(A
);
1350 end Make_Field_Assign
;
1352 ------------------------
1353 -- Make_Field_Assigns --
1354 ------------------------
1356 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
is
1363 while Present
(Item
) loop
1365 -- Look for components, but exclude _tag field assignment if
1366 -- the special Componentwise_Assignment flag is set.
1368 if Nkind
(Item
) = N_Component_Declaration
1369 and then not (Is_Tag
(Defining_Identifier
(Item
))
1370 and then Componentwise_Assignment
(N
))
1373 (Result
, Make_Field_Assign
(Defining_Identifier
(Item
)));
1380 end Make_Field_Assigns
;
1382 -- Start of processing for Expand_Assign_Record
1385 -- Note that we use the base types for this processing. This results
1386 -- in some extra work in the constrained case, but the change of
1387 -- representation case is so unusual that it is not worth the effort.
1389 -- First copy the discriminants. This is done unconditionally. It
1390 -- is required in the unconstrained left side case, and also in the
1391 -- case where this assignment was constructed during the expansion
1392 -- of a type conversion (since initialization of discriminants is
1393 -- suppressed in this case). It is unnecessary but harmless in
1396 if Has_Discriminants
(L_Typ
) then
1397 F
:= First_Discriminant
(R_Typ
);
1398 while Present
(F
) loop
1400 -- If we are expanding the initialization of a derived record
1401 -- that constrains or renames discriminants of the parent, we
1402 -- must use the corresponding discriminant in the parent.
1409 and then Present
(Corresponding_Discriminant
(F
))
1411 CF
:= Corresponding_Discriminant
(F
);
1416 if Is_Unchecked_Union
(Base_Type
(R_Typ
)) then
1417 Insert_Action
(N
, Make_Field_Assign
(CF
, True));
1419 Insert_Action
(N
, Make_Field_Assign
(CF
));
1422 Next_Discriminant
(F
);
1427 -- We know the underlying type is a record, but its current view
1428 -- may be private. We must retrieve the usable record declaration.
1430 if Nkind_In
(Decl
, N_Private_Type_Declaration
,
1431 N_Private_Extension_Declaration
)
1432 and then Present
(Full_View
(R_Typ
))
1434 RDef
:= Type_Definition
(Declaration_Node
(Full_View
(R_Typ
)));
1436 RDef
:= Type_Definition
(Decl
);
1439 if Nkind
(RDef
) = N_Derived_Type_Definition
then
1440 RDef
:= Record_Extension_Part
(RDef
);
1443 if Nkind
(RDef
) = N_Record_Definition
1444 and then Present
(Component_List
(RDef
))
1446 if Is_Unchecked_Union
(R_Typ
) then
1448 Make_Component_List_Assign
(Component_List
(RDef
), True));
1451 (N
, Make_Component_List_Assign
(Component_List
(RDef
)));
1454 Rewrite
(N
, Make_Null_Statement
(Loc
));
1457 end Expand_Assign_Record
;
1459 -----------------------------------
1460 -- Expand_N_Assignment_Statement --
1461 -----------------------------------
1463 -- This procedure implements various cases where an assignment statement
1464 -- cannot just be passed on to the back end in untransformed state.
1466 procedure Expand_N_Assignment_Statement
(N
: Node_Id
) is
1467 Loc
: constant Source_Ptr
:= Sloc
(N
);
1468 Lhs
: constant Node_Id
:= Name
(N
);
1469 Rhs
: constant Node_Id
:= Expression
(N
);
1470 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Lhs
));
1474 -- Special case to check right away, if the Componentwise_Assignment
1475 -- flag is set, this is a reanalysis from the expansion of the primitive
1476 -- assignment procedure for a tagged type, and all we need to do is to
1477 -- expand to assignment of components, because otherwise, we would get
1478 -- infinite recursion (since this looks like a tagged assignment which
1479 -- would normally try to *call* the primitive assignment procedure).
1481 if Componentwise_Assignment
(N
) then
1482 Expand_Assign_Record
(N
);
1486 -- Defend against invalid subscripts on left side if we are in standard
1487 -- validity checking mode. No need to do this if we are checking all
1490 -- Note that we do this right away, because there are some early return
1491 -- paths in this procedure, and this is required on all paths.
1493 if Validity_Checks_On
1494 and then Validity_Check_Default
1495 and then not Validity_Check_Subscripts
1497 Check_Valid_Lvalue_Subscripts
(Lhs
);
1500 -- Ada 2005 (AI-327): Handle assignment to priority of protected object
1502 -- Rewrite an assignment to X'Priority into a run-time call
1504 -- For example: X'Priority := New_Prio_Expr;
1505 -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr);
1507 -- Note that although X'Priority is notionally an object, it is quite
1508 -- deliberately not defined as an aliased object in the RM. This means
1509 -- that it works fine to rewrite it as a call, without having to worry
1510 -- about complications that would other arise from X'Priority'Access,
1511 -- which is illegal, because of the lack of aliasing.
1513 if Ada_Version
>= Ada_05
then
1516 Conctyp
: Entity_Id
;
1519 RT_Subprg_Name
: Node_Id
;
1522 -- Handle chains of renamings
1525 while Nkind
(Ent
) in N_Has_Entity
1526 and then Present
(Entity
(Ent
))
1527 and then Present
(Renamed_Object
(Entity
(Ent
)))
1529 Ent
:= Renamed_Object
(Entity
(Ent
));
1532 -- The attribute Priority applied to protected objects has been
1533 -- previously expanded into a call to the Get_Ceiling run-time
1536 if Nkind
(Ent
) = N_Function_Call
1537 and then (Entity
(Name
(Ent
)) = RTE
(RE_Get_Ceiling
)
1539 Entity
(Name
(Ent
)) = RTE
(RO_PE_Get_Ceiling
))
1541 -- Look for the enclosing concurrent type
1543 Conctyp
:= Current_Scope
;
1544 while not Is_Concurrent_Type
(Conctyp
) loop
1545 Conctyp
:= Scope
(Conctyp
);
1548 pragma Assert
(Is_Protected_Type
(Conctyp
));
1550 -- Generate the first actual of the call
1552 Subprg
:= Current_Scope
;
1553 while not Present
(Protected_Body_Subprogram
(Subprg
)) loop
1554 Subprg
:= Scope
(Subprg
);
1557 -- Select the appropriate run-time call
1559 if Number_Entries
(Conctyp
) = 0 then
1561 New_Reference_To
(RTE
(RE_Set_Ceiling
), Loc
);
1564 New_Reference_To
(RTE
(RO_PE_Set_Ceiling
), Loc
);
1568 Make_Procedure_Call_Statement
(Loc
,
1569 Name
=> RT_Subprg_Name
,
1570 Parameter_Associations
=> New_List
(
1571 New_Copy_Tree
(First
(Parameter_Associations
(Ent
))),
1572 Relocate_Node
(Expression
(N
))));
1581 -- First deal with generation of range check if required
1583 if Do_Range_Check
(Rhs
) then
1584 Set_Do_Range_Check
(Rhs
, False);
1585 Generate_Range_Check
(Rhs
, Typ
, CE_Range_Check_Failed
);
1588 -- Check for a special case where a high level transformation is
1589 -- required. If we have either of:
1594 -- where P is a reference to a bit packed array, then we have to unwind
1595 -- the assignment. The exact meaning of being a reference to a bit
1596 -- packed array is as follows:
1598 -- An indexed component whose prefix is a bit packed array is a
1599 -- reference to a bit packed array.
1601 -- An indexed component or selected component whose prefix is a
1602 -- reference to a bit packed array is itself a reference ot a
1603 -- bit packed array.
1605 -- The required transformation is
1607 -- Tnn : prefix_type := P;
1608 -- Tnn.field := rhs;
1613 -- Tnn : prefix_type := P;
1614 -- Tnn (subscr) := rhs;
1617 -- Since P is going to be evaluated more than once, any subscripts
1618 -- in P must have their evaluation forced.
1620 if Nkind_In
(Lhs
, N_Indexed_Component
, N_Selected_Component
)
1621 and then Is_Ref_To_Bit_Packed_Array
(Prefix
(Lhs
))
1624 BPAR_Expr
: constant Node_Id
:= Relocate_Node
(Prefix
(Lhs
));
1625 BPAR_Typ
: constant Entity_Id
:= Etype
(BPAR_Expr
);
1626 Tnn
: constant Entity_Id
:=
1627 Make_Defining_Identifier
(Loc
,
1628 Chars
=> New_Internal_Name
('T'));
1631 -- Insert the post assignment first, because we want to copy the
1632 -- BPAR_Expr tree before it gets analyzed in the context of the
1633 -- pre assignment. Note that we do not analyze the post assignment
1634 -- yet (we cannot till we have completed the analysis of the pre
1635 -- assignment). As usual, the analysis of this post assignment
1636 -- will happen on its own when we "run into" it after finishing
1637 -- the current assignment.
1640 Make_Assignment_Statement
(Loc
,
1641 Name
=> New_Copy_Tree
(BPAR_Expr
),
1642 Expression
=> New_Occurrence_Of
(Tnn
, Loc
)));
1644 -- At this stage BPAR_Expr is a reference to a bit packed array
1645 -- where the reference was not expanded in the original tree,
1646 -- since it was on the left side of an assignment. But in the
1647 -- pre-assignment statement (the object definition), BPAR_Expr
1648 -- will end up on the right hand side, and must be reexpanded. To
1649 -- achieve this, we reset the analyzed flag of all selected and
1650 -- indexed components down to the actual indexed component for
1651 -- the packed array.
1655 Set_Analyzed
(Exp
, False);
1658 (Exp
, N_Selected_Component
, N_Indexed_Component
)
1660 Exp
:= Prefix
(Exp
);
1666 -- Now we can insert and analyze the pre-assignment
1668 -- If the right-hand side requires a transient scope, it has
1669 -- already been placed on the stack. However, the declaration is
1670 -- inserted in the tree outside of this scope, and must reflect
1671 -- the proper scope for its variable. This awkward bit is forced
1672 -- by the stricter scope discipline imposed by GCC 2.97.
1675 Uses_Transient_Scope
: constant Boolean :=
1677 and then N
= Node_To_Be_Wrapped
;
1680 if Uses_Transient_Scope
then
1681 Push_Scope
(Scope
(Current_Scope
));
1684 Insert_Before_And_Analyze
(N
,
1685 Make_Object_Declaration
(Loc
,
1686 Defining_Identifier
=> Tnn
,
1687 Object_Definition
=> New_Occurrence_Of
(BPAR_Typ
, Loc
),
1688 Expression
=> BPAR_Expr
));
1690 if Uses_Transient_Scope
then
1695 -- Now fix up the original assignment and continue processing
1697 Rewrite
(Prefix
(Lhs
),
1698 New_Occurrence_Of
(Tnn
, Loc
));
1700 -- We do not need to reanalyze that assignment, and we do not need
1701 -- to worry about references to the temporary, but we do need to
1702 -- make sure that the temporary is not marked as a true constant
1703 -- since we now have a generated assignment to it!
1705 Set_Is_True_Constant
(Tnn
, False);
1709 -- When we have the appropriate type of aggregate in the expression (it
1710 -- has been determined during analysis of the aggregate by setting the
1711 -- delay flag), let's perform in place assignment and thus avoid
1712 -- creating a temporary.
1714 if Is_Delayed_Aggregate
(Rhs
) then
1715 Convert_Aggr_In_Assignment
(N
);
1716 Rewrite
(N
, Make_Null_Statement
(Loc
));
1721 -- Apply discriminant check if required. If Lhs is an access type to a
1722 -- designated type with discriminants, we must always check.
1724 if Has_Discriminants
(Etype
(Lhs
)) then
1726 -- Skip discriminant check if change of representation. Will be
1727 -- done when the change of representation is expanded out.
1729 if not Change_Of_Representation
(N
) then
1730 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
), Lhs
);
1733 -- If the type is private without discriminants, and the full type
1734 -- has discriminants (necessarily with defaults) a check may still be
1735 -- necessary if the Lhs is aliased. The private determinants must be
1736 -- visible to build the discriminant constraints.
1738 -- Only an explicit dereference that comes from source indicates
1739 -- aliasing. Access to formals of protected operations and entries
1740 -- create dereferences but are not semantic aliasings.
1742 elsif Is_Private_Type
(Etype
(Lhs
))
1743 and then Has_Discriminants
(Typ
)
1744 and then Nkind
(Lhs
) = N_Explicit_Dereference
1745 and then Comes_From_Source
(Lhs
)
1748 Lt
: constant Entity_Id
:= Etype
(Lhs
);
1750 Set_Etype
(Lhs
, Typ
);
1751 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
1752 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
1753 Set_Etype
(Lhs
, Lt
);
1756 -- If the Lhs has a private type with unknown discriminants, it
1757 -- may have a full view with discriminants, but those are nameable
1758 -- only in the underlying type, so convert the Rhs to it before
1759 -- potential checking.
1761 elsif Has_Unknown_Discriminants
(Base_Type
(Etype
(Lhs
)))
1762 and then Has_Discriminants
(Typ
)
1764 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
1765 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
1767 -- In the access type case, we need the same discriminant check, and
1768 -- also range checks if we have an access to constrained array.
1770 elsif Is_Access_Type
(Etype
(Lhs
))
1771 and then Is_Constrained
(Designated_Type
(Etype
(Lhs
)))
1773 if Has_Discriminants
(Designated_Type
(Etype
(Lhs
))) then
1775 -- Skip discriminant check if change of representation. Will be
1776 -- done when the change of representation is expanded out.
1778 if not Change_Of_Representation
(N
) then
1779 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
));
1782 elsif Is_Array_Type
(Designated_Type
(Etype
(Lhs
))) then
1783 Apply_Range_Check
(Rhs
, Etype
(Lhs
));
1785 if Is_Constrained
(Etype
(Lhs
)) then
1786 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
1789 if Nkind
(Rhs
) = N_Allocator
then
1791 Target_Typ
: constant Entity_Id
:= Etype
(Expression
(Rhs
));
1792 C_Es
: Check_Result
;
1799 Etype
(Designated_Type
(Etype
(Lhs
))));
1811 -- Apply range check for access type case
1813 elsif Is_Access_Type
(Etype
(Lhs
))
1814 and then Nkind
(Rhs
) = N_Allocator
1815 and then Nkind
(Expression
(Rhs
)) = N_Qualified_Expression
1817 Analyze_And_Resolve
(Expression
(Rhs
));
1819 (Expression
(Rhs
), Designated_Type
(Etype
(Lhs
)));
1822 -- Ada 2005 (AI-231): Generate the run-time check
1824 if Is_Access_Type
(Typ
)
1825 and then Can_Never_Be_Null
(Etype
(Lhs
))
1826 and then not Can_Never_Be_Null
(Etype
(Rhs
))
1828 Apply_Constraint_Check
(Rhs
, Etype
(Lhs
));
1831 -- Case of assignment to a bit packed array element
1833 if Nkind
(Lhs
) = N_Indexed_Component
1834 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Lhs
)))
1836 Expand_Bit_Packed_Element_Set
(N
);
1839 -- Build-in-place function call case. Note that we're not yet doing
1840 -- build-in-place for user-written assignment statements (the assignment
1841 -- here came from an aggregate.)
1843 elsif Ada_Version
>= Ada_05
1844 and then Is_Build_In_Place_Function_Call
(Rhs
)
1846 Make_Build_In_Place_Call_In_Assignment
(N
, Rhs
);
1848 elsif Is_Tagged_Type
(Typ
) and then Is_Value_Type
(Etype
(Lhs
)) then
1850 -- Nothing to do for valuetypes
1851 -- ??? Set_Scope_Is_Transient (False);
1855 elsif Is_Tagged_Type
(Typ
)
1856 or else (Needs_Finalization
(Typ
) and then not Is_Array_Type
(Typ
))
1858 Tagged_Case
: declare
1859 L
: List_Id
:= No_List
;
1860 Expand_Ctrl_Actions
: constant Boolean := not No_Ctrl_Actions
(N
);
1863 -- In the controlled case, we ensure that function calls are
1864 -- evaluated before finalizing the target. In all cases, it makes
1865 -- the expansion easier if the side-effects are removed first.
1867 Remove_Side_Effects
(Lhs
);
1868 Remove_Side_Effects
(Rhs
);
1870 -- Avoid recursion in the mechanism
1874 -- If dispatching assignment, we need to dispatch to _assign
1876 if Is_Class_Wide_Type
(Typ
)
1878 -- If the type is tagged, we may as well use the predefined
1879 -- primitive assignment. This avoids inlining a lot of code
1880 -- and in the class-wide case, the assignment is replaced by
1881 -- dispatch call to _assign. Note that this cannot be done when
1882 -- discriminant checks are locally suppressed (as in extension
1883 -- aggregate expansions) because otherwise the discriminant
1884 -- check will be performed within the _assign call. It is also
1885 -- suppressed for assignments created by the expander that
1886 -- correspond to initializations, where we do want to copy the
1887 -- tag (No_Ctrl_Actions flag set True) by the expander and we
1888 -- do not need to mess with tags ever (Expand_Ctrl_Actions flag
1889 -- is set True in this case).
1891 or else (Is_Tagged_Type
(Typ
)
1892 and then not Is_Value_Type
(Etype
(Lhs
))
1893 and then Chars
(Current_Scope
) /= Name_uAssign
1894 and then Expand_Ctrl_Actions
1895 and then not Discriminant_Checks_Suppressed
(Empty
))
1897 -- Fetch the primitive op _assign and proper type to call it.
1898 -- Because of possible conflicts between private and full view,
1899 -- fetch the proper type directly from the operation profile.
1902 Op
: constant Entity_Id
:=
1903 Find_Prim_Op
(Typ
, Name_uAssign
);
1904 F_Typ
: Entity_Id
:= Etype
(First_Formal
(Op
));
1907 -- If the assignment is dispatching, make sure to use the
1910 if Is_Class_Wide_Type
(Typ
) then
1911 F_Typ
:= Class_Wide_Type
(F_Typ
);
1916 -- In case of assignment to a class-wide tagged type, before
1917 -- the assignment we generate run-time check to ensure that
1918 -- the tags of source and target match.
1920 if Is_Class_Wide_Type
(Typ
)
1921 and then Is_Tagged_Type
(Typ
)
1922 and then Is_Tagged_Type
(Underlying_Type
(Etype
(Rhs
)))
1925 Make_Raise_Constraint_Error
(Loc
,
1929 Make_Selected_Component
(Loc
,
1930 Prefix
=> Duplicate_Subexpr
(Lhs
),
1932 Make_Identifier
(Loc
,
1933 Chars
=> Name_uTag
)),
1935 Make_Selected_Component
(Loc
,
1936 Prefix
=> Duplicate_Subexpr
(Rhs
),
1938 Make_Identifier
(Loc
,
1939 Chars
=> Name_uTag
))),
1940 Reason
=> CE_Tag_Check_Failed
));
1944 Make_Procedure_Call_Statement
(Loc
,
1945 Name
=> New_Reference_To
(Op
, Loc
),
1946 Parameter_Associations
=> New_List
(
1947 Unchecked_Convert_To
(F_Typ
,
1948 Duplicate_Subexpr
(Lhs
)),
1949 Unchecked_Convert_To
(F_Typ
,
1950 Duplicate_Subexpr
(Rhs
)))));
1954 L
:= Make_Tag_Ctrl_Assignment
(N
);
1956 -- We can't afford to have destructive Finalization Actions in
1957 -- the Self assignment case, so if the target and the source
1958 -- are not obviously different, code is generated to avoid the
1959 -- self assignment case:
1961 -- if lhs'address /= rhs'address then
1962 -- <code for controlled and/or tagged assignment>
1965 -- Skip this if Restriction (No_Finalization) is active
1967 if not Statically_Different
(Lhs
, Rhs
)
1968 and then Expand_Ctrl_Actions
1969 and then not Restriction_Active
(No_Finalization
)
1972 Make_Implicit_If_Statement
(N
,
1976 Make_Attribute_Reference
(Loc
,
1977 Prefix
=> Duplicate_Subexpr
(Lhs
),
1978 Attribute_Name
=> Name_Address
),
1981 Make_Attribute_Reference
(Loc
,
1982 Prefix
=> Duplicate_Subexpr
(Rhs
),
1983 Attribute_Name
=> Name_Address
)),
1985 Then_Statements
=> L
));
1988 -- We need to set up an exception handler for implementing
1989 -- 7.6.1(18). The remaining adjustments are tackled by the
1990 -- implementation of adjust for record_controllers (see
1993 -- This is skipped if we have no finalization
1995 if Expand_Ctrl_Actions
1996 and then not Restriction_Active
(No_Finalization
)
1999 Make_Block_Statement
(Loc
,
2000 Handled_Statement_Sequence
=>
2001 Make_Handled_Sequence_Of_Statements
(Loc
,
2003 Exception_Handlers
=> New_List
(
2004 Make_Handler_For_Ctrl_Operation
(Loc
)))));
2009 Make_Block_Statement
(Loc
,
2010 Handled_Statement_Sequence
=>
2011 Make_Handled_Sequence_Of_Statements
(Loc
, Statements
=> L
)));
2013 -- If no restrictions on aborts, protect the whole assignment
2014 -- for controlled objects as per 9.8(11).
2016 if Needs_Finalization
(Typ
)
2017 and then Expand_Ctrl_Actions
2018 and then Abort_Allowed
2021 Blk
: constant Entity_Id
:=
2023 (E_Block
, Current_Scope
, Sloc
(N
), 'B');
2026 Set_Scope
(Blk
, Current_Scope
);
2027 Set_Etype
(Blk
, Standard_Void_Type
);
2028 Set_Identifier
(N
, New_Occurrence_Of
(Blk
, Sloc
(N
)));
2030 Prepend_To
(L
, Build_Runtime_Call
(Loc
, RE_Abort_Defer
));
2031 Set_At_End_Proc
(Handled_Statement_Sequence
(N
),
2032 New_Occurrence_Of
(RTE
(RE_Abort_Undefer_Direct
), Loc
));
2033 Expand_At_End_Handler
2034 (Handled_Statement_Sequence
(N
), Blk
);
2038 -- N has been rewritten to a block statement for which it is
2039 -- known by construction that no checks are necessary: analyze
2040 -- it with all checks suppressed.
2042 Analyze
(N
, Suppress
=> All_Checks
);
2048 elsif Is_Array_Type
(Typ
) then
2050 Actual_Rhs
: Node_Id
:= Rhs
;
2053 while Nkind_In
(Actual_Rhs
, N_Type_Conversion
,
2054 N_Qualified_Expression
)
2056 Actual_Rhs
:= Expression
(Actual_Rhs
);
2059 Expand_Assign_Array
(N
, Actual_Rhs
);
2065 elsif Is_Record_Type
(Typ
) then
2066 Expand_Assign_Record
(N
);
2069 -- Scalar types. This is where we perform the processing related to the
2070 -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid
2073 elsif Is_Scalar_Type
(Typ
) then
2075 -- Case where right side is known valid
2077 if Expr_Known_Valid
(Rhs
) then
2079 -- Here the right side is valid, so it is fine. The case to deal
2080 -- with is when the left side is a local variable reference whose
2081 -- value is not currently known to be valid. If this is the case,
2082 -- and the assignment appears in an unconditional context, then
2083 -- we can mark the left side as now being valid if one of these
2084 -- conditions holds:
2086 -- The expression of the right side has Do_Range_Check set so
2087 -- that we know a range check will be performed. Note that it
2088 -- can be the case that a range check is omitted because we
2089 -- make the assumption that we can assume validity for operands
2090 -- appearing in the right side in determining whether a range
2091 -- check is required
2093 -- The subtype of the right side matches the subtype of the
2094 -- left side. In this case, even though we have not checked
2095 -- the range of the right side, we know it is in range of its
2096 -- subtype if the expression is valid.
2098 if Is_Local_Variable_Reference
(Lhs
)
2099 and then not Is_Known_Valid
(Entity
(Lhs
))
2100 and then In_Unconditional_Context
(N
)
2102 if Do_Range_Check
(Rhs
)
2103 or else Etype
(Lhs
) = Etype
(Rhs
)
2105 Set_Is_Known_Valid
(Entity
(Lhs
), True);
2109 -- Case where right side may be invalid in the sense of the RM
2110 -- reference above. The RM does not require that we check for the
2111 -- validity on an assignment, but it does require that the assignment
2112 -- of an invalid value not cause erroneous behavior.
2114 -- The general approach in GNAT is to use the Is_Known_Valid flag
2115 -- to avoid the need for validity checking on assignments. However
2116 -- in some cases, we have to do validity checking in order to make
2117 -- sure that the setting of this flag is correct.
2120 -- Validate right side if we are validating copies
2122 if Validity_Checks_On
2123 and then Validity_Check_Copies
2125 -- Skip this if left hand side is an array or record component
2126 -- and elementary component validity checks are suppressed.
2128 if Nkind_In
(Lhs
, N_Selected_Component
, N_Indexed_Component
)
2129 and then not Validity_Check_Components
2136 -- We can propagate this to the left side where appropriate
2138 if Is_Local_Variable_Reference
(Lhs
)
2139 and then not Is_Known_Valid
(Entity
(Lhs
))
2140 and then In_Unconditional_Context
(N
)
2142 Set_Is_Known_Valid
(Entity
(Lhs
), True);
2145 -- Otherwise check to see what should be done
2147 -- If left side is a local variable, then we just set its flag to
2148 -- indicate that its value may no longer be valid, since we are
2149 -- copying a potentially invalid value.
2151 elsif Is_Local_Variable_Reference
(Lhs
) then
2152 Set_Is_Known_Valid
(Entity
(Lhs
), False);
2154 -- Check for case of a nonlocal variable on the left side which
2155 -- is currently known to be valid. In this case, we simply ensure
2156 -- that the right side is valid. We only play the game of copying
2157 -- validity status for local variables, since we are doing this
2158 -- statically, not by tracing the full flow graph.
2160 elsif Is_Entity_Name
(Lhs
)
2161 and then Is_Known_Valid
(Entity
(Lhs
))
2163 -- Note: If Validity_Checking mode is set to none, we ignore
2164 -- the Ensure_Valid call so don't worry about that case here.
2168 -- In all other cases, we can safely copy an invalid value without
2169 -- worrying about the status of the left side. Since it is not a
2170 -- variable reference it will not be considered
2171 -- as being known to be valid in any case.
2180 when RE_Not_Available
=>
2182 end Expand_N_Assignment_Statement
;
2184 ------------------------------
2185 -- Expand_N_Block_Statement --
2186 ------------------------------
2188 -- Encode entity names defined in block statement
2190 procedure Expand_N_Block_Statement
(N
: Node_Id
) is
2192 Qualify_Entity_Names
(N
);
2193 end Expand_N_Block_Statement
;
2195 -----------------------------
2196 -- Expand_N_Case_Statement --
2197 -----------------------------
2199 procedure Expand_N_Case_Statement
(N
: Node_Id
) is
2200 Loc
: constant Source_Ptr
:= Sloc
(N
);
2201 Expr
: constant Node_Id
:= Expression
(N
);
2209 -- Check for the situation where we know at compile time which branch
2212 if Compile_Time_Known_Value
(Expr
) then
2213 Alt
:= Find_Static_Alternative
(N
);
2215 -- Move statements from this alternative after the case statement.
2216 -- They are already analyzed, so will be skipped by the analyzer.
2218 Insert_List_After
(N
, Statements
(Alt
));
2220 -- That leaves the case statement as a shell. So now we can kill all
2221 -- other alternatives in the case statement.
2223 Kill_Dead_Code
(Expression
(N
));
2229 -- Loop through case alternatives, skipping pragmas, and skipping
2230 -- the one alternative that we select (and therefore retain).
2232 A
:= First
(Alternatives
(N
));
2233 while Present
(A
) loop
2235 and then Nkind
(A
) = N_Case_Statement_Alternative
2237 Kill_Dead_Code
(Statements
(A
), Warn_On_Deleted_Code
);
2244 Rewrite
(N
, Make_Null_Statement
(Loc
));
2248 -- Here if the choice is not determined at compile time
2251 Last_Alt
: constant Node_Id
:= Last
(Alternatives
(N
));
2253 Others_Present
: Boolean;
2254 Others_Node
: Node_Id
;
2256 Then_Stms
: List_Id
;
2257 Else_Stms
: List_Id
;
2260 if Nkind
(First
(Discrete_Choices
(Last_Alt
))) = N_Others_Choice
then
2261 Others_Present
:= True;
2262 Others_Node
:= Last_Alt
;
2264 Others_Present
:= False;
2267 -- First step is to worry about possible invalid argument. The RM
2268 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
2269 -- outside the base range), then Constraint_Error must be raised.
2271 -- Case of validity check required (validity checks are on, the
2272 -- expression is not known to be valid, and the case statement
2273 -- comes from source -- no need to validity check internally
2274 -- generated case statements).
2276 if Validity_Check_Default
then
2277 Ensure_Valid
(Expr
);
2280 -- If there is only a single alternative, just replace it with the
2281 -- sequence of statements since obviously that is what is going to
2282 -- be executed in all cases.
2284 Len
:= List_Length
(Alternatives
(N
));
2287 -- We still need to evaluate the expression if it has any
2290 Remove_Side_Effects
(Expression
(N
));
2292 Insert_List_After
(N
, Statements
(First
(Alternatives
(N
))));
2294 -- That leaves the case statement as a shell. The alternative that
2295 -- will be executed is reset to a null list. So now we can kill
2296 -- the entire case statement.
2298 Kill_Dead_Code
(Expression
(N
));
2299 Rewrite
(N
, Make_Null_Statement
(Loc
));
2303 -- An optimization. If there are only two alternatives, and only
2304 -- a single choice, then rewrite the whole case statement as an
2305 -- if statement, since this can result in subsequent optimizations.
2306 -- This helps not only with case statements in the source of a
2307 -- simple form, but also with generated code (discriminant check
2308 -- functions in particular)
2311 Chlist
:= Discrete_Choices
(First
(Alternatives
(N
)));
2313 if List_Length
(Chlist
) = 1 then
2314 Choice
:= First
(Chlist
);
2316 Then_Stms
:= Statements
(First
(Alternatives
(N
)));
2317 Else_Stms
:= Statements
(Last
(Alternatives
(N
)));
2319 -- For TRUE, generate "expression", not expression = true
2321 if Nkind
(Choice
) = N_Identifier
2322 and then Entity
(Choice
) = Standard_True
2324 Cond
:= Expression
(N
);
2326 -- For FALSE, generate "expression" and switch then/else
2328 elsif Nkind
(Choice
) = N_Identifier
2329 and then Entity
(Choice
) = Standard_False
2331 Cond
:= Expression
(N
);
2332 Else_Stms
:= Statements
(First
(Alternatives
(N
)));
2333 Then_Stms
:= Statements
(Last
(Alternatives
(N
)));
2335 -- For a range, generate "expression in range"
2337 elsif Nkind
(Choice
) = N_Range
2338 or else (Nkind
(Choice
) = N_Attribute_Reference
2339 and then Attribute_Name
(Choice
) = Name_Range
)
2340 or else (Is_Entity_Name
(Choice
)
2341 and then Is_Type
(Entity
(Choice
)))
2342 or else Nkind
(Choice
) = N_Subtype_Indication
2346 Left_Opnd
=> Expression
(N
),
2347 Right_Opnd
=> Relocate_Node
(Choice
));
2349 -- For any other subexpression "expression = value"
2354 Left_Opnd
=> Expression
(N
),
2355 Right_Opnd
=> Relocate_Node
(Choice
));
2358 -- Now rewrite the case as an IF
2361 Make_If_Statement
(Loc
,
2363 Then_Statements
=> Then_Stms
,
2364 Else_Statements
=> Else_Stms
));
2370 -- If the last alternative is not an Others choice, replace it with
2371 -- an N_Others_Choice. Note that we do not bother to call Analyze on
2372 -- the modified case statement, since it's only effect would be to
2373 -- compute the contents of the Others_Discrete_Choices which is not
2374 -- needed by the back end anyway.
2376 -- The reason we do this is that the back end always needs some
2377 -- default for a switch, so if we have not supplied one in the
2378 -- processing above for validity checking, then we need to supply
2381 if not Others_Present
then
2382 Others_Node
:= Make_Others_Choice
(Sloc
(Last_Alt
));
2383 Set_Others_Discrete_Choices
2384 (Others_Node
, Discrete_Choices
(Last_Alt
));
2385 Set_Discrete_Choices
(Last_Alt
, New_List
(Others_Node
));
2388 end Expand_N_Case_Statement
;
2390 -----------------------------
2391 -- Expand_N_Exit_Statement --
2392 -----------------------------
2394 -- The only processing required is to deal with a possible C/Fortran
2395 -- boolean value used as the condition for the exit statement.
2397 procedure Expand_N_Exit_Statement
(N
: Node_Id
) is
2399 Adjust_Condition
(Condition
(N
));
2400 end Expand_N_Exit_Statement
;
2402 ----------------------------------------
2403 -- Expand_N_Extended_Return_Statement --
2404 ----------------------------------------
2406 -- If there is a Handled_Statement_Sequence, we rewrite this:
2408 -- return Result : T := <expression> do
2409 -- <handled_seq_of_stms>
2415 -- Result : T := <expression>;
2417 -- <handled_seq_of_stms>
2421 -- Otherwise (no Handled_Statement_Sequence), we rewrite this:
2423 -- return Result : T := <expression>;
2427 -- return <expression>;
2429 -- unless it's build-in-place or there's no <expression>, in which case
2433 -- Result : T := <expression>;
2438 -- Note that this case could have been written by the user as an extended
2439 -- return statement, or could have been transformed to this from a simple
2440 -- return statement.
2442 -- That is, we need to have a reified return object if there are statements
2443 -- (which might refer to it) or if we're doing build-in-place (so we can
2444 -- set its address to the final resting place or if there is no expression
2445 -- (in which case default initial values might need to be set).
2447 procedure Expand_N_Extended_Return_Statement
(N
: Node_Id
) is
2448 Loc
: constant Source_Ptr
:= Sloc
(N
);
2450 Return_Object_Entity
: constant Entity_Id
:=
2451 First_Entity
(Return_Statement_Entity
(N
));
2452 Return_Object_Decl
: constant Node_Id
:=
2453 Parent
(Return_Object_Entity
);
2454 Parent_Function
: constant Entity_Id
:=
2455 Return_Applies_To
(Return_Statement_Entity
(N
));
2456 Parent_Function_Typ
: constant Entity_Id
:= Etype
(Parent_Function
);
2457 Is_Build_In_Place
: constant Boolean :=
2458 Is_Build_In_Place_Function
(Parent_Function
);
2460 Return_Stm
: Node_Id
;
2461 Statements
: List_Id
;
2462 Handled_Stm_Seq
: Node_Id
;
2466 function Has_Controlled_Parts
(Typ
: Entity_Id
) return Boolean;
2467 -- Determine whether type Typ is controlled or contains a controlled
2470 function Move_Activation_Chain
return Node_Id
;
2471 -- Construct a call to System.Tasking.Stages.Move_Activation_Chain
2473 -- From current activation chain
2474 -- To activation chain passed in by the caller
2475 -- New_Master master passed in by the caller
2477 function Move_Final_List
return Node_Id
;
2478 -- Construct call to System.Finalization_Implementation.Move_Final_List
2481 -- From finalization list of the return statement
2482 -- To finalization list passed in by the caller
2484 --------------------------
2485 -- Has_Controlled_Parts --
2486 --------------------------
2488 function Has_Controlled_Parts
(Typ
: Entity_Id
) return Boolean is
2492 or else Has_Controlled_Component
(Typ
);
2493 end Has_Controlled_Parts
;
2495 ---------------------------
2496 -- Move_Activation_Chain --
2497 ---------------------------
2499 function Move_Activation_Chain
return Node_Id
is
2500 Activation_Chain_Formal
: constant Entity_Id
:=
2501 Build_In_Place_Formal
2502 (Parent_Function
, BIP_Activation_Chain
);
2503 To
: constant Node_Id
:=
2505 (Activation_Chain_Formal
, Loc
);
2506 Master_Formal
: constant Entity_Id
:=
2507 Build_In_Place_Formal
2508 (Parent_Function
, BIP_Master
);
2509 New_Master
: constant Node_Id
:=
2510 New_Reference_To
(Master_Formal
, Loc
);
2512 Chain_Entity
: Entity_Id
;
2516 Chain_Entity
:= First_Entity
(Return_Statement_Entity
(N
));
2517 while Chars
(Chain_Entity
) /= Name_uChain
loop
2518 Chain_Entity
:= Next_Entity
(Chain_Entity
);
2522 Make_Attribute_Reference
(Loc
,
2523 Prefix
=> New_Reference_To
(Chain_Entity
, Loc
),
2524 Attribute_Name
=> Name_Unrestricted_Access
);
2525 -- ??? Not clear why "Make_Identifier (Loc, Name_uChain)" doesn't
2526 -- work, instead of "New_Reference_To (Chain_Entity, Loc)" above.
2529 Make_Procedure_Call_Statement
(Loc
,
2530 Name
=> New_Reference_To
(RTE
(RE_Move_Activation_Chain
), Loc
),
2531 Parameter_Associations
=> New_List
(From
, To
, New_Master
));
2532 end Move_Activation_Chain
;
2534 ---------------------
2535 -- Move_Final_List --
2536 ---------------------
2538 function Move_Final_List
return Node_Id
is
2539 Flist
: constant Entity_Id
:=
2540 Finalization_Chain_Entity
(Return_Statement_Entity
(N
));
2542 From
: constant Node_Id
:= New_Reference_To
(Flist
, Loc
);
2544 Caller_Final_List
: constant Entity_Id
:=
2545 Build_In_Place_Formal
2546 (Parent_Function
, BIP_Final_List
);
2548 To
: constant Node_Id
:= New_Reference_To
(Caller_Final_List
, Loc
);
2551 -- Catch cases where a finalization chain entity has not been
2552 -- associated with the return statement entity.
2554 pragma Assert
(Present
(Flist
));
2556 -- Build required call
2559 Make_If_Statement
(Loc
,
2562 Left_Opnd
=> New_Copy
(From
),
2563 Right_Opnd
=> New_Node
(N_Null
, Loc
)),
2566 Make_Procedure_Call_Statement
(Loc
,
2567 Name
=> New_Reference_To
(RTE
(RE_Move_Final_List
), Loc
),
2568 Parameter_Associations
=> New_List
(From
, To
))));
2569 end Move_Final_List
;
2571 -- Start of processing for Expand_N_Extended_Return_Statement
2574 if Nkind
(Return_Object_Decl
) = N_Object_Declaration
then
2575 Exp
:= Expression
(Return_Object_Decl
);
2580 Handled_Stm_Seq
:= Handled_Statement_Sequence
(N
);
2582 -- Build a simple_return_statement that returns the return object when
2583 -- there is a statement sequence, or no expression, or the result will
2584 -- be built in place. Note however that we currently do this for all
2585 -- composite cases, even though nonlimited composite results are not yet
2586 -- built in place (though we plan to do so eventually).
2588 if Present
(Handled_Stm_Seq
)
2589 or else Is_Composite_Type
(Etype
(Parent_Function
))
2592 if No
(Handled_Stm_Seq
) then
2593 Statements
:= New_List
;
2595 -- If the extended return has a handled statement sequence, then wrap
2596 -- it in a block and use the block as the first statement.
2600 New_List
(Make_Block_Statement
(Loc
,
2601 Declarations
=> New_List
,
2602 Handled_Statement_Sequence
=> Handled_Stm_Seq
));
2605 -- If control gets past the above Statements, we have successfully
2606 -- completed the return statement. If the result type has controlled
2607 -- parts and the return is for a build-in-place function, then we
2608 -- call Move_Final_List to transfer responsibility for finalization
2609 -- of the return object to the caller. An alternative would be to
2610 -- declare a Success flag in the function, initialize it to False,
2611 -- and set it to True here. Then move the Move_Final_List call into
2612 -- the cleanup code, and check Success. If Success then make a call
2613 -- to Move_Final_List else do finalization. Then we can remove the
2614 -- abort-deferral and the nulling-out of the From parameter from
2615 -- Move_Final_List. Note that the current method is not quite correct
2616 -- in the rather obscure case of a select-then-abort statement whose
2617 -- abortable part contains the return statement.
2619 -- Check the type of the function to determine whether to move the
2620 -- finalization list. A special case arises when processing a simple
2621 -- return statement which has been rewritten as an extended return.
2622 -- In that case check the type of the returned object or the original
2625 if Is_Build_In_Place
2627 (Has_Controlled_Parts
(Parent_Function_Typ
)
2628 or else (Is_Class_Wide_Type
(Parent_Function_Typ
)
2630 Has_Controlled_Parts
(Root_Type
(Parent_Function_Typ
)))
2631 or else Has_Controlled_Parts
(Etype
(Return_Object_Entity
))
2632 or else (Present
(Exp
)
2633 and then Has_Controlled_Parts
(Etype
(Exp
))))
2635 Append_To
(Statements
, Move_Final_List
);
2638 -- Similarly to the above Move_Final_List, if the result type
2639 -- contains tasks, we call Move_Activation_Chain. Later, the cleanup
2640 -- code will call Complete_Master, which will terminate any
2641 -- unactivated tasks belonging to the return statement master. But
2642 -- Move_Activation_Chain updates their master to be that of the
2643 -- caller, so they will not be terminated unless the return statement
2644 -- completes unsuccessfully due to exception, abort, goto, or exit.
2645 -- As a formality, we test whether the function requires the result
2646 -- to be built in place, though that's necessarily true for the case
2647 -- of result types with task parts.
2649 if Is_Build_In_Place
and Has_Task
(Etype
(Parent_Function
)) then
2650 Append_To
(Statements
, Move_Activation_Chain
);
2653 -- Build a simple_return_statement that returns the return object
2656 Make_Simple_Return_Statement
(Loc
,
2657 Expression
=> New_Occurrence_Of
(Return_Object_Entity
, Loc
));
2658 Append_To
(Statements
, Return_Stm
);
2661 Make_Handled_Sequence_Of_Statements
(Loc
, Statements
);
2664 -- Case where we build a block
2666 if Present
(Handled_Stm_Seq
) then
2668 Make_Block_Statement
(Loc
,
2669 Declarations
=> Return_Object_Declarations
(N
),
2670 Handled_Statement_Sequence
=> Handled_Stm_Seq
);
2672 -- We set the entity of the new block statement to be that of the
2673 -- return statement. This is necessary so that various fields, such
2674 -- as Finalization_Chain_Entity carry over from the return statement
2675 -- to the block. Note that this block is unusual, in that its entity
2676 -- is an E_Return_Statement rather than an E_Block.
2679 (Result
, New_Occurrence_Of
(Return_Statement_Entity
(N
), Loc
));
2681 -- If the object decl was already rewritten as a renaming, then
2682 -- we don't want to do the object allocation and transformation of
2683 -- of the return object declaration to a renaming. This case occurs
2684 -- when the return object is initialized by a call to another
2685 -- build-in-place function, and that function is responsible for the
2686 -- allocation of the return object.
2688 if Is_Build_In_Place
2690 Nkind
(Return_Object_Decl
) = N_Object_Renaming_Declaration
2692 pragma Assert
(Nkind
(Original_Node
(Return_Object_Decl
)) =
2693 N_Object_Declaration
2694 and then Is_Build_In_Place_Function_Call
2695 (Expression
(Original_Node
(Return_Object_Decl
))));
2697 Set_By_Ref
(Return_Stm
); -- Return build-in-place results by ref
2699 elsif Is_Build_In_Place
then
2701 -- Locate the implicit access parameter associated with the
2702 -- caller-supplied return object and convert the return
2703 -- statement's return object declaration to a renaming of a
2704 -- dereference of the access parameter. If the return object's
2705 -- declaration includes an expression that has not already been
2706 -- expanded as separate assignments, then add an assignment
2707 -- statement to ensure the return object gets initialized.
2710 -- Result : T [:= <expression>];
2717 -- Result : T renames FuncRA.all;
2718 -- [Result := <expression;]
2723 Return_Obj_Id
: constant Entity_Id
:=
2724 Defining_Identifier
(Return_Object_Decl
);
2725 Return_Obj_Typ
: constant Entity_Id
:= Etype
(Return_Obj_Id
);
2726 Return_Obj_Expr
: constant Node_Id
:=
2727 Expression
(Return_Object_Decl
);
2728 Result_Subt
: constant Entity_Id
:=
2729 Etype
(Parent_Function
);
2730 Constr_Result
: constant Boolean :=
2731 Is_Constrained
(Result_Subt
);
2732 Obj_Alloc_Formal
: Entity_Id
;
2733 Object_Access
: Entity_Id
;
2734 Obj_Acc_Deref
: Node_Id
;
2735 Init_Assignment
: Node_Id
:= Empty
;
2738 -- Build-in-place results must be returned by reference
2740 Set_By_Ref
(Return_Stm
);
2742 -- Retrieve the implicit access parameter passed by the caller
2745 Build_In_Place_Formal
(Parent_Function
, BIP_Object_Access
);
2747 -- If the return object's declaration includes an expression
2748 -- and the declaration isn't marked as No_Initialization, then
2749 -- we need to generate an assignment to the object and insert
2750 -- it after the declaration before rewriting it as a renaming
2751 -- (otherwise we'll lose the initialization). The case where
2752 -- the result type is an interface (or class-wide interface)
2753 -- is also excluded because the context of the function call
2754 -- must be unconstrained, so the initialization will always
2755 -- be done as part of an allocator evaluation (storage pool
2756 -- or secondary stack), never to a constrained target object
2757 -- passed in by the caller. Besides the assignment being
2758 -- unneeded in this case, it avoids problems with trying to
2759 -- generate a dispatching assignment when the return expression
2760 -- is a nonlimited descendant of a limited interface (the
2761 -- interface has no assignment operation).
2763 if Present
(Return_Obj_Expr
)
2764 and then not No_Initialization
(Return_Object_Decl
)
2765 and then not Is_Interface
(Return_Obj_Typ
)
2768 Make_Assignment_Statement
(Loc
,
2769 Name
=> New_Reference_To
(Return_Obj_Id
, Loc
),
2770 Expression
=> Relocate_Node
(Return_Obj_Expr
));
2771 Set_Etype
(Name
(Init_Assignment
), Etype
(Return_Obj_Id
));
2772 Set_Assignment_OK
(Name
(Init_Assignment
));
2773 Set_No_Ctrl_Actions
(Init_Assignment
);
2775 Set_Parent
(Name
(Init_Assignment
), Init_Assignment
);
2776 Set_Parent
(Expression
(Init_Assignment
), Init_Assignment
);
2778 Set_Expression
(Return_Object_Decl
, Empty
);
2780 if Is_Class_Wide_Type
(Etype
(Return_Obj_Id
))
2781 and then not Is_Class_Wide_Type
2782 (Etype
(Expression
(Init_Assignment
)))
2784 Rewrite
(Expression
(Init_Assignment
),
2785 Make_Type_Conversion
(Loc
,
2788 (Etype
(Return_Obj_Id
), Loc
),
2790 Relocate_Node
(Expression
(Init_Assignment
))));
2793 -- In the case of functions where the calling context can
2794 -- determine the form of allocation needed, initialization
2795 -- is done with each part of the if statement that handles
2796 -- the different forms of allocation (this is true for
2797 -- unconstrained and tagged result subtypes).
2800 and then not Is_Tagged_Type
(Underlying_Type
(Result_Subt
))
2802 Insert_After
(Return_Object_Decl
, Init_Assignment
);
2806 -- When the function's subtype is unconstrained, a run-time
2807 -- test is needed to determine the form of allocation to use
2808 -- for the return object. The function has an implicit formal
2809 -- parameter indicating this. If the BIP_Alloc_Form formal has
2810 -- the value one, then the caller has passed access to an
2811 -- existing object for use as the return object. If the value
2812 -- is two, then the return object must be allocated on the
2813 -- secondary stack. Otherwise, the object must be allocated in
2814 -- a storage pool (currently only supported for the global
2815 -- heap, user-defined storage pools TBD ???). We generate an
2816 -- if statement to test the implicit allocation formal and
2817 -- initialize a local access value appropriately, creating
2818 -- allocators in the secondary stack and global heap cases.
2819 -- The special formal also exists and must be tested when the
2820 -- function has a tagged result, even when the result subtype
2821 -- is constrained, because in general such functions can be
2822 -- called in dispatching contexts and must be handled similarly
2823 -- to functions with a class-wide result.
2825 if not Constr_Result
2826 or else Is_Tagged_Type
(Underlying_Type
(Result_Subt
))
2829 Build_In_Place_Formal
(Parent_Function
, BIP_Alloc_Form
);
2832 Ref_Type
: Entity_Id
;
2833 Ptr_Type_Decl
: Node_Id
;
2834 Alloc_Obj_Id
: Entity_Id
;
2835 Alloc_Obj_Decl
: Node_Id
;
2836 Alloc_If_Stmt
: Node_Id
;
2837 SS_Allocator
: Node_Id
;
2838 Heap_Allocator
: Node_Id
;
2841 -- Reuse the itype created for the function's implicit
2842 -- access formal. This avoids the need to create a new
2843 -- access type here, plus it allows assigning the access
2844 -- formal directly without applying a conversion.
2846 -- Ref_Type := Etype (Object_Access);
2848 -- Create an access type designating the function's
2852 Make_Defining_Identifier
(Loc
, New_Internal_Name
('A'));
2855 Make_Full_Type_Declaration
(Loc
,
2856 Defining_Identifier
=> Ref_Type
,
2858 Make_Access_To_Object_Definition
(Loc
,
2859 All_Present
=> True,
2860 Subtype_Indication
=>
2861 New_Reference_To
(Return_Obj_Typ
, Loc
)));
2863 Insert_Before
(Return_Object_Decl
, Ptr_Type_Decl
);
2865 -- Create an access object that will be initialized to an
2866 -- access value denoting the return object, either coming
2867 -- from an implicit access value passed in by the caller
2868 -- or from the result of an allocator.
2871 Make_Defining_Identifier
(Loc
,
2872 Chars
=> New_Internal_Name
('R'));
2873 Set_Etype
(Alloc_Obj_Id
, Ref_Type
);
2876 Make_Object_Declaration
(Loc
,
2877 Defining_Identifier
=> Alloc_Obj_Id
,
2878 Object_Definition
=> New_Reference_To
2881 Insert_Before
(Return_Object_Decl
, Alloc_Obj_Decl
);
2883 -- Create allocators for both the secondary stack and
2884 -- global heap. If there's an initialization expression,
2885 -- then create these as initialized allocators.
2887 if Present
(Return_Obj_Expr
)
2888 and then not No_Initialization
(Return_Object_Decl
)
2890 -- Always use the type of the expression for the
2891 -- qualified expression, rather than the result type.
2892 -- In general we cannot always use the result type
2893 -- for the allocator, because the expression might be
2894 -- of a specific type, such as in the case of an
2895 -- aggregate or even a nonlimited object when the
2896 -- result type is a limited class-wide interface type.
2899 Make_Allocator
(Loc
,
2901 Make_Qualified_Expression
(Loc
,
2904 (Etype
(Return_Obj_Expr
), Loc
),
2906 New_Copy_Tree
(Return_Obj_Expr
)));
2909 -- If the function returns a class-wide type we cannot
2910 -- use the return type for the allocator. Instead we
2911 -- use the type of the expression, which must be an
2912 -- aggregate of a definite type.
2914 if Is_Class_Wide_Type
(Return_Obj_Typ
) then
2916 Make_Allocator
(Loc
,
2919 (Etype
(Return_Obj_Expr
), Loc
));
2922 Make_Allocator
(Loc
,
2924 New_Reference_To
(Return_Obj_Typ
, Loc
));
2927 -- If the object requires default initialization then
2928 -- that will happen later following the elaboration of
2929 -- the object renaming. If we don't turn it off here
2930 -- then the object will be default initialized twice.
2932 Set_No_Initialization
(Heap_Allocator
);
2935 -- If the No_Allocators restriction is active, then only
2936 -- an allocator for secondary stack allocation is needed.
2937 -- It's OK for such allocators to have Comes_From_Source
2938 -- set to False, because gigi knows not to flag them as
2939 -- being a violation of No_Implicit_Heap_Allocations.
2941 if Restriction_Active
(No_Allocators
) then
2942 SS_Allocator
:= Heap_Allocator
;
2943 Heap_Allocator
:= Make_Null
(Loc
);
2945 -- Otherwise the heap allocator may be needed, so we make
2946 -- another allocator for secondary stack allocation.
2949 SS_Allocator
:= New_Copy_Tree
(Heap_Allocator
);
2951 -- The heap allocator is marked Comes_From_Source
2952 -- since it corresponds to an explicit user-written
2953 -- allocator (that is, it will only be executed on
2954 -- behalf of callers that call the function as
2955 -- initialization for such an allocator). This
2956 -- prevents errors when No_Implicit_Heap_Allocations
2959 Set_Comes_From_Source
(Heap_Allocator
, True);
2962 -- The allocator is returned on the secondary stack. We
2963 -- don't do this on VM targets, since the SS is not used.
2965 if VM_Target
= No_VM
then
2966 Set_Storage_Pool
(SS_Allocator
, RTE
(RE_SS_Pool
));
2967 Set_Procedure_To_Call
2968 (SS_Allocator
, RTE
(RE_SS_Allocate
));
2970 -- The allocator is returned on the secondary stack,
2971 -- so indicate that the function return, as well as
2972 -- the block that encloses the allocator, must not
2973 -- release it. The flags must be set now because the
2974 -- decision to use the secondary stack is done very
2975 -- late in the course of expanding the return
2976 -- statement, past the point where these flags are
2979 Set_Sec_Stack_Needed_For_Return
(Parent_Function
);
2980 Set_Sec_Stack_Needed_For_Return
2981 (Return_Statement_Entity
(N
));
2982 Set_Uses_Sec_Stack
(Parent_Function
);
2983 Set_Uses_Sec_Stack
(Return_Statement_Entity
(N
));
2986 -- Create an if statement to test the BIP_Alloc_Form
2987 -- formal and initialize the access object to either the
2988 -- BIP_Object_Access formal (BIP_Alloc_Form = 0), the
2989 -- result of allocating the object in the secondary stack
2990 -- (BIP_Alloc_Form = 1), or else an allocator to create
2991 -- the return object in the heap (BIP_Alloc_Form = 2).
2993 -- ??? An unchecked type conversion must be made in the
2994 -- case of assigning the access object formal to the
2995 -- local access object, because a normal conversion would
2996 -- be illegal in some cases (such as converting access-
2997 -- to-unconstrained to access-to-constrained), but the
2998 -- the unchecked conversion will presumably fail to work
2999 -- right in just such cases. It's not clear at all how to
3003 Make_If_Statement
(Loc
,
3007 New_Reference_To
(Obj_Alloc_Formal
, Loc
),
3009 Make_Integer_Literal
(Loc
,
3010 UI_From_Int
(BIP_Allocation_Form
'Pos
3011 (Caller_Allocation
)))),
3013 New_List
(Make_Assignment_Statement
(Loc
,
3016 (Alloc_Obj_Id
, Loc
),
3018 Make_Unchecked_Type_Conversion
(Loc
,
3020 New_Reference_To
(Ref_Type
, Loc
),
3023 (Object_Access
, Loc
)))),
3025 New_List
(Make_Elsif_Part
(Loc
,
3030 (Obj_Alloc_Formal
, Loc
),
3032 Make_Integer_Literal
(Loc
,
3034 BIP_Allocation_Form
'Pos
3035 (Secondary_Stack
)))),
3038 (Make_Assignment_Statement
(Loc
,
3041 (Alloc_Obj_Id
, Loc
),
3045 New_List
(Make_Assignment_Statement
(Loc
,
3048 (Alloc_Obj_Id
, Loc
),
3052 -- If a separate initialization assignment was created
3053 -- earlier, append that following the assignment of the
3054 -- implicit access formal to the access object, to ensure
3055 -- that the return object is initialized in that case.
3056 -- In this situation, the target of the assignment must
3057 -- be rewritten to denote a dereference of the access to
3058 -- the return object passed in by the caller.
3060 if Present
(Init_Assignment
) then
3061 Rewrite
(Name
(Init_Assignment
),
3062 Make_Explicit_Dereference
(Loc
,
3063 Prefix
=> New_Reference_To
(Alloc_Obj_Id
, Loc
)));
3065 (Name
(Init_Assignment
), Etype
(Return_Obj_Id
));
3068 (Then_Statements
(Alloc_If_Stmt
),
3072 Insert_Before
(Return_Object_Decl
, Alloc_If_Stmt
);
3074 -- Remember the local access object for use in the
3075 -- dereference of the renaming created below.
3077 Object_Access
:= Alloc_Obj_Id
;
3081 -- Replace the return object declaration with a renaming of a
3082 -- dereference of the access value designating the return
3086 Make_Explicit_Dereference
(Loc
,
3087 Prefix
=> New_Reference_To
(Object_Access
, Loc
));
3089 Rewrite
(Return_Object_Decl
,
3090 Make_Object_Renaming_Declaration
(Loc
,
3091 Defining_Identifier
=> Return_Obj_Id
,
3092 Access_Definition
=> Empty
,
3093 Subtype_Mark
=> New_Occurrence_Of
3094 (Return_Obj_Typ
, Loc
),
3095 Name
=> Obj_Acc_Deref
));
3097 Set_Renamed_Object
(Return_Obj_Id
, Obj_Acc_Deref
);
3101 -- Case where we do not build a block
3104 -- We're about to drop Return_Object_Declarations on the floor, so
3105 -- we need to insert it, in case it got expanded into useful code.
3107 Insert_List_Before
(N
, Return_Object_Declarations
(N
));
3109 -- Build simple_return_statement that returns the expression directly
3111 Return_Stm
:= Make_Simple_Return_Statement
(Loc
, Expression
=> Exp
);
3113 Result
:= Return_Stm
;
3116 -- Set the flag to prevent infinite recursion
3118 Set_Comes_From_Extended_Return_Statement
(Return_Stm
);
3120 Rewrite
(N
, Result
);
3122 end Expand_N_Extended_Return_Statement
;
3124 -----------------------------
3125 -- Expand_N_Goto_Statement --
3126 -----------------------------
3128 -- Add poll before goto if polling active
3130 procedure Expand_N_Goto_Statement
(N
: Node_Id
) is
3132 Generate_Poll_Call
(N
);
3133 end Expand_N_Goto_Statement
;
3135 ---------------------------
3136 -- Expand_N_If_Statement --
3137 ---------------------------
3139 -- First we deal with the case of C and Fortran convention boolean values,
3140 -- with zero/non-zero semantics.
3142 -- Second, we deal with the obvious rewriting for the cases where the
3143 -- condition of the IF is known at compile time to be True or False.
3145 -- Third, we remove elsif parts which have non-empty Condition_Actions and
3146 -- rewrite as independent if statements. For example:
3157 -- <<condition actions of y>>
3163 -- This rewriting is needed if at least one elsif part has a non-empty
3164 -- Condition_Actions list. We also do the same processing if there is a
3165 -- constant condition in an elsif part (in conjunction with the first
3166 -- processing step mentioned above, for the recursive call made to deal
3167 -- with the created inner if, this deals with properly optimizing the
3168 -- cases of constant elsif conditions).
3170 procedure Expand_N_If_Statement
(N
: Node_Id
) is
3171 Loc
: constant Source_Ptr
:= Sloc
(N
);
3176 Warn_If_Deleted
: constant Boolean :=
3177 Warn_On_Deleted_Code
and then Comes_From_Source
(N
);
3178 -- Indicates whether we want warnings when we delete branches of the
3179 -- if statement based on constant condition analysis. We never want
3180 -- these warnings for expander generated code.
3183 Adjust_Condition
(Condition
(N
));
3185 -- The following loop deals with constant conditions for the IF. We
3186 -- need a loop because as we eliminate False conditions, we grab the
3187 -- first elsif condition and use it as the primary condition.
3189 while Compile_Time_Known_Value
(Condition
(N
)) loop
3191 -- If condition is True, we can simply rewrite the if statement now
3192 -- by replacing it by the series of then statements.
3194 if Is_True
(Expr_Value
(Condition
(N
))) then
3196 -- All the else parts can be killed
3198 Kill_Dead_Code
(Elsif_Parts
(N
), Warn_If_Deleted
);
3199 Kill_Dead_Code
(Else_Statements
(N
), Warn_If_Deleted
);
3201 Hed
:= Remove_Head
(Then_Statements
(N
));
3202 Insert_List_After
(N
, Then_Statements
(N
));
3206 -- If condition is False, then we can delete the condition and
3207 -- the Then statements
3210 -- We do not delete the condition if constant condition warnings
3211 -- are enabled, since otherwise we end up deleting the desired
3212 -- warning. Of course the backend will get rid of this True/False
3213 -- test anyway, so nothing is lost here.
3215 if not Constant_Condition_Warnings
then
3216 Kill_Dead_Code
(Condition
(N
));
3219 Kill_Dead_Code
(Then_Statements
(N
), Warn_If_Deleted
);
3221 -- If there are no elsif statements, then we simply replace the
3222 -- entire if statement by the sequence of else statements.
3224 if No
(Elsif_Parts
(N
)) then
3225 if No
(Else_Statements
(N
))
3226 or else Is_Empty_List
(Else_Statements
(N
))
3229 Make_Null_Statement
(Sloc
(N
)));
3231 Hed
:= Remove_Head
(Else_Statements
(N
));
3232 Insert_List_After
(N
, Else_Statements
(N
));
3238 -- If there are elsif statements, the first of them becomes the
3239 -- if/then section of the rebuilt if statement This is the case
3240 -- where we loop to reprocess this copied condition.
3243 Hed
:= Remove_Head
(Elsif_Parts
(N
));
3244 Insert_Actions
(N
, Condition_Actions
(Hed
));
3245 Set_Condition
(N
, Condition
(Hed
));
3246 Set_Then_Statements
(N
, Then_Statements
(Hed
));
3248 -- Hed might have been captured as the condition determining
3249 -- the current value for an entity. Now it is detached from
3250 -- the tree, so a Current_Value pointer in the condition might
3251 -- need to be updated.
3253 Set_Current_Value_Condition
(N
);
3255 if Is_Empty_List
(Elsif_Parts
(N
)) then
3256 Set_Elsif_Parts
(N
, No_List
);
3262 -- Loop through elsif parts, dealing with constant conditions and
3263 -- possible expression actions that are present.
3265 if Present
(Elsif_Parts
(N
)) then
3266 E
:= First
(Elsif_Parts
(N
));
3267 while Present
(E
) loop
3268 Adjust_Condition
(Condition
(E
));
3270 -- If there are condition actions, then rewrite the if statement
3271 -- as indicated above. We also do the same rewrite for a True or
3272 -- False condition. The further processing of this constant
3273 -- condition is then done by the recursive call to expand the
3274 -- newly created if statement
3276 if Present
(Condition_Actions
(E
))
3277 or else Compile_Time_Known_Value
(Condition
(E
))
3279 -- Note this is not an implicit if statement, since it is part
3280 -- of an explicit if statement in the source (or of an implicit
3281 -- if statement that has already been tested).
3284 Make_If_Statement
(Sloc
(E
),
3285 Condition
=> Condition
(E
),
3286 Then_Statements
=> Then_Statements
(E
),
3287 Elsif_Parts
=> No_List
,
3288 Else_Statements
=> Else_Statements
(N
));
3290 -- Elsif parts for new if come from remaining elsif's of parent
3292 while Present
(Next
(E
)) loop
3293 if No
(Elsif_Parts
(New_If
)) then
3294 Set_Elsif_Parts
(New_If
, New_List
);
3297 Append
(Remove_Next
(E
), Elsif_Parts
(New_If
));
3300 Set_Else_Statements
(N
, New_List
(New_If
));
3302 if Present
(Condition_Actions
(E
)) then
3303 Insert_List_Before
(New_If
, Condition_Actions
(E
));
3308 if Is_Empty_List
(Elsif_Parts
(N
)) then
3309 Set_Elsif_Parts
(N
, No_List
);
3315 -- No special processing for that elsif part, move to next
3323 -- Some more optimizations applicable if we still have an IF statement
3325 if Nkind
(N
) /= N_If_Statement
then
3329 -- Another optimization, special cases that can be simplified
3331 -- if expression then
3337 -- can be changed to:
3339 -- return expression;
3343 -- if expression then
3349 -- can be changed to:
3351 -- return not (expression);
3353 -- Only do these optimizations if we are at least at -O1 level and
3354 -- do not do them if control flow optimizations are suppressed.
3356 if Optimization_Level
> 0
3357 and then not Opt
.Suppress_Control_Flow_Optimizations
3359 if Nkind
(N
) = N_If_Statement
3360 and then No
(Elsif_Parts
(N
))
3361 and then Present
(Else_Statements
(N
))
3362 and then List_Length
(Then_Statements
(N
)) = 1
3363 and then List_Length
(Else_Statements
(N
)) = 1
3366 Then_Stm
: constant Node_Id
:= First
(Then_Statements
(N
));
3367 Else_Stm
: constant Node_Id
:= First
(Else_Statements
(N
));
3370 if Nkind
(Then_Stm
) = N_Simple_Return_Statement
3372 Nkind
(Else_Stm
) = N_Simple_Return_Statement
3375 Then_Expr
: constant Node_Id
:= Expression
(Then_Stm
);
3376 Else_Expr
: constant Node_Id
:= Expression
(Else_Stm
);
3379 if Nkind
(Then_Expr
) = N_Identifier
3381 Nkind
(Else_Expr
) = N_Identifier
3383 if Entity
(Then_Expr
) = Standard_True
3384 and then Entity
(Else_Expr
) = Standard_False
3387 Make_Simple_Return_Statement
(Loc
,
3388 Expression
=> Relocate_Node
(Condition
(N
))));
3392 elsif Entity
(Then_Expr
) = Standard_False
3393 and then Entity
(Else_Expr
) = Standard_True
3396 Make_Simple_Return_Statement
(Loc
,
3400 Relocate_Node
(Condition
(N
)))));
3410 end Expand_N_If_Statement
;
3412 -----------------------------
3413 -- Expand_N_Loop_Statement --
3414 -----------------------------
3416 -- 1. Remove null loop entirely
3417 -- 2. Deal with while condition for C/Fortran boolean
3418 -- 3. Deal with loops with a non-standard enumeration type range
3419 -- 4. Deal with while loops where Condition_Actions is set
3420 -- 5. Insert polling call if required
3422 procedure Expand_N_Loop_Statement
(N
: Node_Id
) is
3423 Loc
: constant Source_Ptr
:= Sloc
(N
);
3424 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
3429 if Is_Null_Loop
(N
) then
3430 Rewrite
(N
, Make_Null_Statement
(Loc
));
3434 -- Deal with condition for C/Fortran Boolean
3436 if Present
(Isc
) then
3437 Adjust_Condition
(Condition
(Isc
));
3440 -- Generate polling call
3442 if Is_Non_Empty_List
(Statements
(N
)) then
3443 Generate_Poll_Call
(First
(Statements
(N
)));
3446 -- Nothing more to do for plain loop with no iteration scheme
3452 -- Note: we do not have to worry about validity checking of the for loop
3453 -- range bounds here, since they were frozen with constant declarations
3454 -- and it is during that process that the validity checking is done.
3456 -- Handle the case where we have a for loop with the range type being an
3457 -- enumeration type with non-standard representation. In this case we
3460 -- for x in [reverse] a .. b loop
3466 -- for xP in [reverse] integer
3467 -- range etype'Pos (a) .. etype'Pos (b) loop
3469 -- x : constant etype := Pos_To_Rep (xP);
3475 if Present
(Loop_Parameter_Specification
(Isc
)) then
3477 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Isc
);
3478 Loop_Id
: constant Entity_Id
:= Defining_Identifier
(LPS
);
3479 Ltype
: constant Entity_Id
:= Etype
(Loop_Id
);
3480 Btype
: constant Entity_Id
:= Base_Type
(Ltype
);
3485 if not Is_Enumeration_Type
(Btype
)
3486 or else No
(Enum_Pos_To_Rep
(Btype
))
3492 Make_Defining_Identifier
(Loc
,
3493 Chars
=> New_External_Name
(Chars
(Loop_Id
), 'P'));
3495 -- If the type has a contiguous representation, successive values
3496 -- can be generated as offsets from the first literal.
3498 if Has_Contiguous_Rep
(Btype
) then
3500 Unchecked_Convert_To
(Btype
,
3503 Make_Integer_Literal
(Loc
,
3504 Enumeration_Rep
(First_Literal
(Btype
))),
3505 Right_Opnd
=> New_Reference_To
(New_Id
, Loc
)));
3507 -- Use the constructed array Enum_Pos_To_Rep
3510 Make_Indexed_Component
(Loc
,
3511 Prefix
=> New_Reference_To
(Enum_Pos_To_Rep
(Btype
), Loc
),
3512 Expressions
=> New_List
(New_Reference_To
(New_Id
, Loc
)));
3516 Make_Loop_Statement
(Loc
,
3517 Identifier
=> Identifier
(N
),
3520 Make_Iteration_Scheme
(Loc
,
3521 Loop_Parameter_Specification
=>
3522 Make_Loop_Parameter_Specification
(Loc
,
3523 Defining_Identifier
=> New_Id
,
3524 Reverse_Present
=> Reverse_Present
(LPS
),
3526 Discrete_Subtype_Definition
=>
3527 Make_Subtype_Indication
(Loc
,
3530 New_Reference_To
(Standard_Natural
, Loc
),
3533 Make_Range_Constraint
(Loc
,
3538 Make_Attribute_Reference
(Loc
,
3540 New_Reference_To
(Btype
, Loc
),
3542 Attribute_Name
=> Name_Pos
,
3544 Expressions
=> New_List
(
3546 (Type_Low_Bound
(Ltype
)))),
3549 Make_Attribute_Reference
(Loc
,
3551 New_Reference_To
(Btype
, Loc
),
3553 Attribute_Name
=> Name_Pos
,
3555 Expressions
=> New_List
(
3557 (Type_High_Bound
(Ltype
))))))))),
3559 Statements
=> New_List
(
3560 Make_Block_Statement
(Loc
,
3561 Declarations
=> New_List
(
3562 Make_Object_Declaration
(Loc
,
3563 Defining_Identifier
=> Loop_Id
,
3564 Constant_Present
=> True,
3565 Object_Definition
=> New_Reference_To
(Ltype
, Loc
),
3566 Expression
=> Expr
)),
3568 Handled_Statement_Sequence
=>
3569 Make_Handled_Sequence_Of_Statements
(Loc
,
3570 Statements
=> Statements
(N
)))),
3572 End_Label
=> End_Label
(N
)));
3576 -- Second case, if we have a while loop with Condition_Actions set, then
3577 -- we change it into a plain loop:
3586 -- <<condition actions>>
3592 and then Present
(Condition_Actions
(Isc
))
3599 Make_Exit_Statement
(Sloc
(Condition
(Isc
)),
3601 Make_Op_Not
(Sloc
(Condition
(Isc
)),
3602 Right_Opnd
=> Condition
(Isc
)));
3604 Prepend
(ES
, Statements
(N
));
3605 Insert_List_Before
(ES
, Condition_Actions
(Isc
));
3607 -- This is not an implicit loop, since it is generated in response
3608 -- to the loop statement being processed. If this is itself
3609 -- implicit, the restriction has already been checked. If not,
3610 -- it is an explicit loop.
3613 Make_Loop_Statement
(Sloc
(N
),
3614 Identifier
=> Identifier
(N
),
3615 Statements
=> Statements
(N
),
3616 End_Label
=> End_Label
(N
)));
3621 end Expand_N_Loop_Statement
;
3623 --------------------------------------
3624 -- Expand_N_Simple_Return_Statement --
3625 --------------------------------------
3627 procedure Expand_N_Simple_Return_Statement
(N
: Node_Id
) is
3629 -- Defend against previous errors (i.e. the return statement calls a
3630 -- function that is not available in configurable runtime).
3632 if Present
(Expression
(N
))
3633 and then Nkind
(Expression
(N
)) = N_Empty
3638 -- Distinguish the function and non-function cases:
3640 case Ekind
(Return_Applies_To
(Return_Statement_Entity
(N
))) is
3643 E_Generic_Function
=>
3644 Expand_Simple_Function_Return
(N
);
3647 E_Generic_Procedure |
3650 E_Return_Statement
=>
3651 Expand_Non_Function_Return
(N
);
3654 raise Program_Error
;
3658 when RE_Not_Available
=>
3660 end Expand_N_Simple_Return_Statement
;
3662 --------------------------------
3663 -- Expand_Non_Function_Return --
3664 --------------------------------
3666 procedure Expand_Non_Function_Return
(N
: Node_Id
) is
3667 pragma Assert
(No
(Expression
(N
)));
3669 Loc
: constant Source_Ptr
:= Sloc
(N
);
3670 Scope_Id
: Entity_Id
:=
3671 Return_Applies_To
(Return_Statement_Entity
(N
));
3672 Kind
: constant Entity_Kind
:= Ekind
(Scope_Id
);
3675 Goto_Stat
: Node_Id
;
3679 -- Call _Postconditions procedure if procedure with active
3680 -- postconditions. Here, we use the Postcondition_Proc attribute, which
3681 -- is needed for implicitly-generated returns. Functions never
3682 -- have implicitly-generated returns, and there's no room for
3683 -- Postcondition_Proc in E_Function, so we look up the identifier
3684 -- Name_uPostconditions for function returns (see
3685 -- Expand_Simple_Function_Return).
3687 if Ekind
(Scope_Id
) = E_Procedure
3688 and then Has_Postconditions
(Scope_Id
)
3690 pragma Assert
(Present
(Postcondition_Proc
(Scope_Id
)));
3692 Make_Procedure_Call_Statement
(Loc
,
3693 Name
=> New_Reference_To
(Postcondition_Proc
(Scope_Id
), Loc
)));
3696 -- If it is a return from a procedure do no extra steps
3698 if Kind
= E_Procedure
or else Kind
= E_Generic_Procedure
then
3701 -- If it is a nested return within an extended one, replace it with a
3702 -- return of the previously declared return object.
3704 elsif Kind
= E_Return_Statement
then
3706 Make_Simple_Return_Statement
(Loc
,
3708 New_Occurrence_Of
(First_Entity
(Scope_Id
), Loc
)));
3709 Set_Comes_From_Extended_Return_Statement
(N
);
3710 Set_Return_Statement_Entity
(N
, Scope_Id
);
3711 Expand_Simple_Function_Return
(N
);
3715 pragma Assert
(Is_Entry
(Scope_Id
));
3717 -- Look at the enclosing block to see whether the return is from an
3718 -- accept statement or an entry body.
3720 for J
in reverse 0 .. Scope_Stack
.Last
loop
3721 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
3722 exit when Is_Concurrent_Type
(Scope_Id
);
3725 -- If it is a return from accept statement it is expanded as call to
3726 -- RTS Complete_Rendezvous and a goto to the end of the accept body.
3728 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
3729 -- Expand_N_Accept_Alternative in exp_ch9.adb)
3731 if Is_Task_Type
(Scope_Id
) then
3734 Make_Procedure_Call_Statement
(Loc
,
3735 Name
=> New_Reference_To
(RTE
(RE_Complete_Rendezvous
), Loc
));
3736 Insert_Before
(N
, Call
);
3737 -- why not insert actions here???
3740 Acc_Stat
:= Parent
(N
);
3741 while Nkind
(Acc_Stat
) /= N_Accept_Statement
loop
3742 Acc_Stat
:= Parent
(Acc_Stat
);
3745 Lab_Node
:= Last
(Statements
3746 (Handled_Statement_Sequence
(Acc_Stat
)));
3748 Goto_Stat
:= Make_Goto_Statement
(Loc
,
3749 Name
=> New_Occurrence_Of
3750 (Entity
(Identifier
(Lab_Node
)), Loc
));
3752 Set_Analyzed
(Goto_Stat
);
3754 Rewrite
(N
, Goto_Stat
);
3757 -- If it is a return from an entry body, put a Complete_Entry_Body call
3758 -- in front of the return.
3760 elsif Is_Protected_Type
(Scope_Id
) then
3762 Make_Procedure_Call_Statement
(Loc
,
3764 New_Reference_To
(RTE
(RE_Complete_Entry_Body
), Loc
),
3765 Parameter_Associations
=> New_List
(
3766 Make_Attribute_Reference
(Loc
,
3769 (Find_Protection_Object
(Current_Scope
), Loc
),
3771 Name_Unchecked_Access
)));
3773 Insert_Before
(N
, Call
);
3776 end Expand_Non_Function_Return
;
3778 -----------------------------------
3779 -- Expand_Simple_Function_Return --
3780 -----------------------------------
3782 -- The "simple" comes from the syntax rule simple_return_statement.
3783 -- The semantics are not at all simple!
3785 procedure Expand_Simple_Function_Return
(N
: Node_Id
) is
3786 Loc
: constant Source_Ptr
:= Sloc
(N
);
3788 Scope_Id
: constant Entity_Id
:=
3789 Return_Applies_To
(Return_Statement_Entity
(N
));
3790 -- The function we are returning from
3792 R_Type
: constant Entity_Id
:= Etype
(Scope_Id
);
3793 -- The result type of the function
3795 Utyp
: constant Entity_Id
:= Underlying_Type
(R_Type
);
3797 Exp
: constant Node_Id
:= Expression
(N
);
3798 pragma Assert
(Present
(Exp
));
3800 Exptyp
: constant Entity_Id
:= Etype
(Exp
);
3801 -- The type of the expression (not necessarily the same as R_Type)
3803 Subtype_Ind
: Node_Id
;
3804 -- If the result type of the function is class-wide and the
3805 -- expression has a specific type, then we use the expression's
3806 -- type as the type of the return object. In cases where the
3807 -- expression is an aggregate that is built in place, this avoids
3808 -- the need for an expensive conversion of the return object to
3809 -- the specific type on assignments to the individual components.
3812 if Is_Class_Wide_Type
(R_Type
)
3813 and then not Is_Class_Wide_Type
(Etype
(Exp
))
3815 Subtype_Ind
:= New_Occurrence_Of
(Etype
(Exp
), Loc
);
3817 Subtype_Ind
:= New_Occurrence_Of
(R_Type
, Loc
);
3820 -- For the case of a simple return that does not come from an extended
3821 -- return, in the case of Ada 2005 where we are returning a limited
3822 -- type, we rewrite "return <expression>;" to be:
3824 -- return _anon_ : <return_subtype> := <expression>
3826 -- The expansion produced by Expand_N_Extended_Return_Statement will
3827 -- contain simple return statements (for example, a block containing
3828 -- simple return of the return object), which brings us back here with
3829 -- Comes_From_Extended_Return_Statement set. The reason for the barrier
3830 -- checking for a simple return that does not come from an extended
3831 -- return is to avoid this infinite recursion.
3833 -- The reason for this design is that for Ada 2005 limited returns, we
3834 -- need to reify the return object, so we can build it "in place", and
3835 -- we need a block statement to hang finalization and tasking stuff.
3837 -- ??? In order to avoid disruption, we avoid translating to extended
3838 -- return except in the cases where we really need to (Ada 2005 for
3839 -- inherently limited). We might prefer to do this translation in all
3840 -- cases (except perhaps for the case of Ada 95 inherently limited),
3841 -- in order to fully exercise the Expand_N_Extended_Return_Statement
3842 -- code. This would also allow us to do the build-in-place optimization
3843 -- for efficiency even in cases where it is semantically not required.
3845 -- As before, we check the type of the return expression rather than the
3846 -- return type of the function, because the latter may be a limited
3847 -- class-wide interface type, which is not a limited type, even though
3848 -- the type of the expression may be.
3850 if not Comes_From_Extended_Return_Statement
(N
)
3851 and then Is_Inherently_Limited_Type
(Etype
(Expression
(N
)))
3852 and then Ada_Version
>= Ada_05
3853 and then not Debug_Flag_Dot_L
3856 Return_Object_Entity
: constant Entity_Id
:=
3857 Make_Defining_Identifier
(Loc
,
3858 New_Internal_Name
('R'));
3859 Obj_Decl
: constant Node_Id
:=
3860 Make_Object_Declaration
(Loc
,
3861 Defining_Identifier
=> Return_Object_Entity
,
3862 Object_Definition
=> Subtype_Ind
,
3865 Ext
: constant Node_Id
:= Make_Extended_Return_Statement
(Loc
,
3866 Return_Object_Declarations
=> New_List
(Obj_Decl
));
3867 -- Do not perform this high-level optimization if the result type
3868 -- is an interface because the "this" pointer must be displaced.
3877 -- Here we have a simple return statement that is part of the expansion
3878 -- of an extended return statement (either written by the user, or
3879 -- generated by the above code).
3881 -- Always normalize C/Fortran boolean result. This is not always needed,
3882 -- but it seems a good idea to minimize the passing around of non-
3883 -- normalized values, and in any case this handles the processing of
3884 -- barrier functions for protected types, which turn the condition into
3885 -- a return statement.
3887 if Is_Boolean_Type
(Exptyp
)
3888 and then Nonzero_Is_True
(Exptyp
)
3890 Adjust_Condition
(Exp
);
3891 Adjust_Result_Type
(Exp
, Exptyp
);
3894 -- Do validity check if enabled for returns
3896 if Validity_Checks_On
3897 and then Validity_Check_Returns
3902 -- Check the result expression of a scalar function against the subtype
3903 -- of the function by inserting a conversion. This conversion must
3904 -- eventually be performed for other classes of types, but for now it's
3905 -- only done for scalars.
3908 if Is_Scalar_Type
(Exptyp
) then
3909 Rewrite
(Exp
, Convert_To
(R_Type
, Exp
));
3911 -- The expression is resolved to ensure that the conversion gets
3912 -- expanded to generate a possible constraint check.
3914 Analyze_And_Resolve
(Exp
, R_Type
);
3917 -- Deal with returning variable length objects and controlled types
3919 -- Nothing to do if we are returning by reference, or this is not a
3920 -- type that requires special processing (indicated by the fact that
3921 -- it requires a cleanup scope for the secondary stack case).
3923 if Is_Inherently_Limited_Type
(Exptyp
)
3924 or else Is_Limited_Interface
(Exptyp
)
3928 elsif not Requires_Transient_Scope
(R_Type
) then
3930 -- Mutable records with no variable length components are not
3931 -- returned on the sec-stack, so we need to make sure that the
3932 -- backend will only copy back the size of the actual value, and not
3933 -- the maximum size. We create an actual subtype for this purpose.
3936 Ubt
: constant Entity_Id
:= Underlying_Type
(Base_Type
(Exptyp
));
3940 if Has_Discriminants
(Ubt
)
3941 and then not Is_Constrained
(Ubt
)
3942 and then not Has_Unchecked_Union
(Ubt
)
3944 Decl
:= Build_Actual_Subtype
(Ubt
, Exp
);
3945 Ent
:= Defining_Identifier
(Decl
);
3946 Insert_Action
(Exp
, Decl
);
3947 Rewrite
(Exp
, Unchecked_Convert_To
(Ent
, Exp
));
3948 Analyze_And_Resolve
(Exp
);
3952 -- Here if secondary stack is used
3955 -- Make sure that no surrounding block will reclaim the secondary
3956 -- stack on which we are going to put the result. Not only may this
3957 -- introduce secondary stack leaks but worse, if the reclamation is
3958 -- done too early, then the result we are returning may get
3965 while Ekind
(S
) = E_Block
or else Ekind
(S
) = E_Loop
loop
3966 Set_Sec_Stack_Needed_For_Return
(S
, True);
3967 S
:= Enclosing_Dynamic_Scope
(S
);
3971 -- Optimize the case where the result is a function call. In this
3972 -- case either the result is already on the secondary stack, or is
3973 -- already being returned with the stack pointer depressed and no
3974 -- further processing is required except to set the By_Ref flag to
3975 -- ensure that gigi does not attempt an extra unnecessary copy.
3976 -- (actually not just unnecessary but harmfully wrong in the case
3977 -- of a controlled type, where gigi does not know how to do a copy).
3978 -- To make up for a gcc 2.8.1 deficiency (???), we perform
3979 -- the copy for array types if the constrained status of the
3980 -- target type is different from that of the expression.
3982 if Requires_Transient_Scope
(Exptyp
)
3984 (not Is_Array_Type
(Exptyp
)
3985 or else Is_Constrained
(Exptyp
) = Is_Constrained
(R_Type
)
3986 or else CW_Or_Has_Controlled_Part
(Utyp
))
3987 and then Nkind
(Exp
) = N_Function_Call
3991 -- Remove side effects from the expression now so that other parts
3992 -- of the expander do not have to reanalyze this node without this
3995 Rewrite
(Exp
, Duplicate_Subexpr_No_Checks
(Exp
));
3997 -- For controlled types, do the allocation on the secondary stack
3998 -- manually in order to call adjust at the right time:
4000 -- type Anon1 is access R_Type;
4001 -- for Anon1'Storage_pool use ss_pool;
4002 -- Anon2 : anon1 := new R_Type'(expr);
4003 -- return Anon2.all;
4005 -- We do the same for classwide types that are not potentially
4006 -- controlled (by the virtue of restriction No_Finalization) because
4007 -- gigi is not able to properly allocate class-wide types.
4009 elsif CW_Or_Has_Controlled_Part
(Utyp
) then
4011 Loc
: constant Source_Ptr
:= Sloc
(N
);
4012 Temp
: constant Entity_Id
:=
4013 Make_Defining_Identifier
(Loc
,
4014 Chars
=> New_Internal_Name
('R'));
4015 Acc_Typ
: constant Entity_Id
:=
4016 Make_Defining_Identifier
(Loc
,
4017 Chars
=> New_Internal_Name
('A'));
4018 Alloc_Node
: Node_Id
;
4021 Set_Ekind
(Acc_Typ
, E_Access_Type
);
4023 Set_Associated_Storage_Pool
(Acc_Typ
, RTE
(RE_SS_Pool
));
4025 -- This is an allocator for the secondary stack, and it's fine
4026 -- to have Comes_From_Source set False on it, as gigi knows not
4027 -- to flag it as a violation of No_Implicit_Heap_Allocations.
4030 Make_Allocator
(Loc
,
4032 Make_Qualified_Expression
(Loc
,
4033 Subtype_Mark
=> New_Reference_To
(Etype
(Exp
), Loc
),
4034 Expression
=> Relocate_Node
(Exp
)));
4036 -- We do not want discriminant checks on the declaration,
4037 -- given that it gets its value from the allocator.
4039 Set_No_Initialization
(Alloc_Node
);
4041 Insert_List_Before_And_Analyze
(N
, New_List
(
4042 Make_Full_Type_Declaration
(Loc
,
4043 Defining_Identifier
=> Acc_Typ
,
4045 Make_Access_To_Object_Definition
(Loc
,
4046 Subtype_Indication
=> Subtype_Ind
)),
4048 Make_Object_Declaration
(Loc
,
4049 Defining_Identifier
=> Temp
,
4050 Object_Definition
=> New_Reference_To
(Acc_Typ
, Loc
),
4051 Expression
=> Alloc_Node
)));
4054 Make_Explicit_Dereference
(Loc
,
4055 Prefix
=> New_Reference_To
(Temp
, Loc
)));
4057 Analyze_And_Resolve
(Exp
, R_Type
);
4060 -- Otherwise use the gigi mechanism to allocate result on the
4064 Check_Restriction
(No_Secondary_Stack
, N
);
4065 Set_Storage_Pool
(N
, RTE
(RE_SS_Pool
));
4067 -- If we are generating code for the VM do not use
4068 -- SS_Allocate since everything is heap-allocated anyway.
4070 if VM_Target
= No_VM
then
4071 Set_Procedure_To_Call
(N
, RTE
(RE_SS_Allocate
));
4076 -- Implement the rules of 6.5(8-10), which require a tag check in the
4077 -- case of a limited tagged return type, and tag reassignment for
4078 -- nonlimited tagged results. These actions are needed when the return
4079 -- type is a specific tagged type and the result expression is a
4080 -- conversion or a formal parameter, because in that case the tag of the
4081 -- expression might differ from the tag of the specific result type.
4083 if Is_Tagged_Type
(Utyp
)
4084 and then not Is_Class_Wide_Type
(Utyp
)
4085 and then (Nkind_In
(Exp
, N_Type_Conversion
,
4086 N_Unchecked_Type_Conversion
)
4087 or else (Is_Entity_Name
(Exp
)
4088 and then Ekind
(Entity
(Exp
)) in Formal_Kind
))
4090 -- When the return type is limited, perform a check that the
4091 -- tag of the result is the same as the tag of the return type.
4093 if Is_Limited_Type
(R_Type
) then
4095 Make_Raise_Constraint_Error
(Loc
,
4099 Make_Selected_Component
(Loc
,
4100 Prefix
=> Duplicate_Subexpr
(Exp
),
4102 New_Reference_To
(First_Tag_Component
(Utyp
), Loc
)),
4104 Unchecked_Convert_To
(RTE
(RE_Tag
),
4107 (Access_Disp_Table
(Base_Type
(Utyp
)))),
4109 Reason
=> CE_Tag_Check_Failed
));
4111 -- If the result type is a specific nonlimited tagged type, then we
4112 -- have to ensure that the tag of the result is that of the result
4113 -- type. This is handled by making a copy of the expression in the
4114 -- case where it might have a different tag, namely when the
4115 -- expression is a conversion or a formal parameter. We create a new
4116 -- object of the result type and initialize it from the expression,
4117 -- which will implicitly force the tag to be set appropriately.
4121 Result_Id
: constant Entity_Id
:=
4122 Make_Defining_Identifier
(Loc
,
4123 Chars
=> New_Internal_Name
('R'));
4124 Result_Exp
: constant Node_Id
:=
4125 New_Reference_To
(Result_Id
, Loc
);
4126 Result_Obj
: constant Node_Id
:=
4127 Make_Object_Declaration
(Loc
,
4128 Defining_Identifier
=> Result_Id
,
4129 Object_Definition
=>
4130 New_Reference_To
(R_Type
, Loc
),
4131 Constant_Present
=> True,
4132 Expression
=> Relocate_Node
(Exp
));
4135 Set_Assignment_OK
(Result_Obj
);
4136 Insert_Action
(Exp
, Result_Obj
);
4138 Rewrite
(Exp
, Result_Exp
);
4139 Analyze_And_Resolve
(Exp
, R_Type
);
4143 -- Ada 2005 (AI-344): If the result type is class-wide, then insert
4144 -- a check that the level of the return expression's underlying type
4145 -- is not deeper than the level of the master enclosing the function.
4146 -- Always generate the check when the type of the return expression
4147 -- is class-wide, when it's a type conversion, or when it's a formal
4148 -- parameter. Otherwise, suppress the check in the case where the
4149 -- return expression has a specific type whose level is known not to
4150 -- be statically deeper than the function's result type.
4152 -- Note: accessibility check is skipped in the VM case, since there
4153 -- does not seem to be any practical way to implement this check.
4155 elsif Ada_Version
>= Ada_05
4156 and then Tagged_Type_Expansion
4157 and then Is_Class_Wide_Type
(R_Type
)
4158 and then not Scope_Suppress
(Accessibility_Check
)
4160 (Is_Class_Wide_Type
(Etype
(Exp
))
4161 or else Nkind_In
(Exp
, N_Type_Conversion
,
4162 N_Unchecked_Type_Conversion
)
4163 or else (Is_Entity_Name
(Exp
)
4164 and then Ekind
(Entity
(Exp
)) in Formal_Kind
)
4165 or else Scope_Depth
(Enclosing_Dynamic_Scope
(Etype
(Exp
))) >
4166 Scope_Depth
(Enclosing_Dynamic_Scope
(Scope_Id
)))
4172 -- Ada 2005 (AI-251): In class-wide interface objects we displace
4173 -- "this" to reference the base of the object --- required to get
4174 -- access to the TSD of the object.
4176 if Is_Class_Wide_Type
(Etype
(Exp
))
4177 and then Is_Interface
(Etype
(Exp
))
4178 and then Nkind
(Exp
) = N_Explicit_Dereference
4181 Make_Explicit_Dereference
(Loc
,
4182 Unchecked_Convert_To
(RTE
(RE_Tag_Ptr
),
4183 Make_Function_Call
(Loc
,
4184 Name
=> New_Reference_To
(RTE
(RE_Base_Address
), Loc
),
4185 Parameter_Associations
=> New_List
(
4186 Unchecked_Convert_To
(RTE
(RE_Address
),
4187 Duplicate_Subexpr
(Prefix
(Exp
)))))));
4190 Make_Attribute_Reference
(Loc
,
4191 Prefix
=> Duplicate_Subexpr
(Exp
),
4192 Attribute_Name
=> Name_Tag
);
4196 Make_Raise_Program_Error
(Loc
,
4200 Build_Get_Access_Level
(Loc
, Tag_Node
),
4202 Make_Integer_Literal
(Loc
,
4203 Scope_Depth
(Enclosing_Dynamic_Scope
(Scope_Id
)))),
4204 Reason
=> PE_Accessibility_Check_Failed
));
4208 -- If we are returning an object that may not be bit-aligned, then
4209 -- copy the value into a temporary first. This copy may need to expand
4210 -- to a loop of component operations..
4212 if Is_Possibly_Unaligned_Slice
(Exp
)
4213 or else Is_Possibly_Unaligned_Object
(Exp
)
4216 Tnn
: constant Entity_Id
:=
4217 Make_Defining_Identifier
(Loc
, New_Internal_Name
('T'));
4220 Make_Object_Declaration
(Loc
,
4221 Defining_Identifier
=> Tnn
,
4222 Constant_Present
=> True,
4223 Object_Definition
=> New_Occurrence_Of
(R_Type
, Loc
),
4224 Expression
=> Relocate_Node
(Exp
)),
4225 Suppress
=> All_Checks
);
4226 Rewrite
(Exp
, New_Occurrence_Of
(Tnn
, Loc
));
4230 -- Generate call to postcondition checks if they are present
4232 if Ekind
(Scope_Id
) = E_Function
4233 and then Has_Postconditions
(Scope_Id
)
4235 -- We are going to reference the returned value twice in this case,
4236 -- once in the call to _Postconditions, and once in the actual return
4237 -- statement, but we can't have side effects happening twice, and in
4238 -- any case for efficiency we don't want to do the computation twice.
4240 -- If the returned expression is an entity name, we don't need to
4241 -- worry since it is efficient and safe to reference it twice, that's
4242 -- also true for literals other than string literals, and for the
4243 -- case of X.all where X is an entity name.
4245 if Is_Entity_Name
(Exp
)
4246 or else Nkind_In
(Exp
, N_Character_Literal
,
4249 or else (Nkind
(Exp
) = N_Explicit_Dereference
4250 and then Is_Entity_Name
(Prefix
(Exp
)))
4254 -- Otherwise we are going to need a temporary to capture the value
4258 Tnn
: constant Entity_Id
:=
4259 Make_Defining_Identifier
(Loc
, New_Internal_Name
('T'));
4262 -- For a complex expression of an elementary type, capture
4263 -- value in the temporary and use it as the reference.
4265 if Is_Elementary_Type
(R_Type
) then
4267 Make_Object_Declaration
(Loc
,
4268 Defining_Identifier
=> Tnn
,
4269 Constant_Present
=> True,
4270 Object_Definition
=> New_Occurrence_Of
(R_Type
, Loc
),
4271 Expression
=> Relocate_Node
(Exp
)),
4272 Suppress
=> All_Checks
);
4274 Rewrite
(Exp
, New_Occurrence_Of
(Tnn
, Loc
));
4276 -- If we have something we can rename, generate a renaming of
4277 -- the object and replace the expression with a reference
4279 elsif Is_Object_Reference
(Exp
) then
4281 Make_Object_Renaming_Declaration
(Loc
,
4282 Defining_Identifier
=> Tnn
,
4283 Subtype_Mark
=> New_Occurrence_Of
(R_Type
, Loc
),
4284 Name
=> Relocate_Node
(Exp
)),
4285 Suppress
=> All_Checks
);
4287 Rewrite
(Exp
, New_Occurrence_Of
(Tnn
, Loc
));
4289 -- Otherwise we have something like a string literal or an
4290 -- aggregate. We could copy the value, but that would be
4291 -- inefficient. Instead we make a reference to the value and
4292 -- capture this reference with a renaming, the expression is
4293 -- then replaced by a dereference of this renaming.
4296 -- For now, copy the value, since the code below does not
4297 -- seem to work correctly ???
4300 Make_Object_Declaration
(Loc
,
4301 Defining_Identifier
=> Tnn
,
4302 Constant_Present
=> True,
4303 Object_Definition
=> New_Occurrence_Of
(R_Type
, Loc
),
4304 Expression
=> Relocate_Node
(Exp
)),
4305 Suppress
=> All_Checks
);
4307 Rewrite
(Exp
, New_Occurrence_Of
(Tnn
, Loc
));
4309 -- Insert_Action (Exp,
4310 -- Make_Object_Renaming_Declaration (Loc,
4311 -- Defining_Identifier => Tnn,
4312 -- Access_Definition =>
4313 -- Make_Access_Definition (Loc,
4314 -- All_Present => True,
4315 -- Subtype_Mark => New_Occurrence_Of (R_Type, Loc)),
4317 -- Make_Reference (Loc,
4318 -- Prefix => Relocate_Node (Exp))),
4319 -- Suppress => All_Checks);
4322 -- Make_Explicit_Dereference (Loc,
4323 -- Prefix => New_Occurrence_Of (Tnn, Loc)));
4328 -- Generate call to _postconditions
4331 Make_Procedure_Call_Statement
(Loc
,
4332 Name
=> Make_Identifier
(Loc
, Name_uPostconditions
),
4333 Parameter_Associations
=> New_List
(Duplicate_Subexpr
(Exp
))));
4336 -- Ada 2005 (AI-251): If this return statement corresponds with an
4337 -- simple return statement associated with an extended return statement
4338 -- and the type of the returned object is an interface then generate an
4339 -- implicit conversion to force displacement of the "this" pointer.
4341 if Ada_Version
>= Ada_05
4342 and then Comes_From_Extended_Return_Statement
(N
)
4343 and then Nkind
(Expression
(N
)) = N_Identifier
4344 and then Is_Interface
(Utyp
)
4345 and then Utyp
/= Underlying_Type
(Exptyp
)
4347 Rewrite
(Exp
, Convert_To
(Utyp
, Relocate_Node
(Exp
)));
4348 Analyze_And_Resolve
(Exp
);
4350 end Expand_Simple_Function_Return
;
4352 ------------------------------
4353 -- Make_Tag_Ctrl_Assignment --
4354 ------------------------------
4356 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
is
4357 Loc
: constant Source_Ptr
:= Sloc
(N
);
4358 L
: constant Node_Id
:= Name
(N
);
4359 T
: constant Entity_Id
:= Underlying_Type
(Etype
(L
));
4361 Ctrl_Act
: constant Boolean := Needs_Finalization
(T
)
4362 and then not No_Ctrl_Actions
(N
);
4364 Component_Assign
: constant Boolean :=
4365 Is_Fully_Repped_Tagged_Type
(T
);
4367 Save_Tag
: constant Boolean := Is_Tagged_Type
(T
)
4368 and then not Component_Assign
4369 and then not No_Ctrl_Actions
(N
)
4370 and then Tagged_Type_Expansion
;
4371 -- Tags are not saved and restored when VM_Target because VM tags are
4372 -- represented implicitly in objects.
4375 Tag_Tmp
: Entity_Id
;
4377 Prev_Tmp
: Entity_Id
;
4378 Next_Tmp
: Entity_Id
;
4384 -- Finalize the target of the assignment when controlled
4386 -- We have two exceptions here:
4388 -- 1. If we are in an init proc since it is an initialization more
4389 -- than an assignment.
4391 -- 2. If the left-hand side is a temporary that was not initialized
4392 -- (or the parent part of a temporary since it is the case in
4393 -- extension aggregates). Such a temporary does not come from
4394 -- source. We must examine the original node for the prefix, because
4395 -- it may be a component of an entry formal, in which case it has
4396 -- been rewritten and does not appear to come from source either.
4398 -- Case of init proc
4400 if not Ctrl_Act
then
4403 -- The left hand side is an uninitialized temporary object
4405 elsif Nkind
(L
) = N_Type_Conversion
4406 and then Is_Entity_Name
(Expression
(L
))
4407 and then Nkind
(Parent
(Entity
(Expression
(L
)))) =
4408 N_Object_Declaration
4409 and then No_Initialization
(Parent
(Entity
(Expression
(L
))))
4414 Append_List_To
(Res
,
4416 (Ref
=> Duplicate_Subexpr_No_Checks
(L
),
4418 With_Detach
=> New_Reference_To
(Standard_False
, Loc
)));
4421 -- Save the Tag in a local variable Tag_Tmp
4425 Make_Defining_Identifier
(Loc
, New_Internal_Name
('A'));
4428 Make_Object_Declaration
(Loc
,
4429 Defining_Identifier
=> Tag_Tmp
,
4430 Object_Definition
=> New_Reference_To
(RTE
(RE_Tag
), Loc
),
4432 Make_Selected_Component
(Loc
,
4433 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
4434 Selector_Name
=> New_Reference_To
(First_Tag_Component
(T
),
4437 -- Otherwise Tag_Tmp not used
4444 if VM_Target
/= No_VM
then
4446 -- Cannot assign part of the object in a VM context, so instead
4447 -- fallback to the previous mechanism, even though it is not
4448 -- completely correct ???
4450 -- Save the Finalization Pointers in local variables Prev_Tmp and
4451 -- Next_Tmp. For objects with Has_Controlled_Component set, these
4452 -- pointers are in the Record_Controller
4454 Ctrl_Ref
:= Duplicate_Subexpr
(L
);
4456 if Has_Controlled_Component
(T
) then
4458 Make_Selected_Component
(Loc
,
4461 New_Reference_To
(Controller_Component
(T
), Loc
));
4465 Make_Defining_Identifier
(Loc
, New_Internal_Name
('B'));
4468 Make_Object_Declaration
(Loc
,
4469 Defining_Identifier
=> Prev_Tmp
,
4471 Object_Definition
=>
4472 New_Reference_To
(RTE
(RE_Finalizable_Ptr
), Loc
),
4475 Make_Selected_Component
(Loc
,
4477 Unchecked_Convert_To
(RTE
(RE_Finalizable
), Ctrl_Ref
),
4478 Selector_Name
=> Make_Identifier
(Loc
, Name_Prev
))));
4481 Make_Defining_Identifier
(Loc
,
4482 Chars
=> New_Internal_Name
('C'));
4485 Make_Object_Declaration
(Loc
,
4486 Defining_Identifier
=> Next_Tmp
,
4488 Object_Definition
=>
4489 New_Reference_To
(RTE
(RE_Finalizable_Ptr
), Loc
),
4492 Make_Selected_Component
(Loc
,
4494 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
4495 New_Copy_Tree
(Ctrl_Ref
)),
4496 Selector_Name
=> Make_Identifier
(Loc
, Name_Next
))));
4498 -- Do the Assignment
4500 Append_To
(Res
, Relocate_Node
(N
));
4503 -- Regular (non VM) processing for controlled types and types with
4504 -- controlled components
4506 -- Variables of such types contain pointers used to chain them in
4507 -- finalization lists, in addition to user data. These pointers
4508 -- are specific to each object of the type, not to the value being
4511 -- Thus they need to be left intact during the assignment. We
4512 -- achieve this by constructing a Storage_Array subtype, and by
4513 -- overlaying objects of this type on the source and target of the
4514 -- assignment. The assignment is then rewritten to assignments of
4515 -- slices of these arrays, copying the user data, and leaving the
4516 -- pointers untouched.
4518 Controlled_Actions
: declare
4520 -- A reference to the Prev component of the record controller
4522 First_After_Root
: Node_Id
:= Empty
;
4523 -- Index of first byte to be copied (used to skip
4524 -- Root_Controlled in controlled objects).
4526 Last_Before_Hole
: Node_Id
:= Empty
;
4527 -- Index of last byte to be copied before outermost record
4530 Hole_Length
: Node_Id
:= Empty
;
4531 -- Length of record controller data (Prev and Next pointers)
4533 First_After_Hole
: Node_Id
:= Empty
;
4534 -- Index of first byte to be copied after outermost record
4537 Expr
, Source_Size
: Node_Id
;
4538 Source_Actual_Subtype
: Entity_Id
;
4539 -- Used for computation of the size of the data to be copied
4541 Range_Type
: Entity_Id
;
4542 Opaque_Type
: Entity_Id
;
4544 function Build_Slice
4547 Hi
: Node_Id
) return Node_Id
;
4548 -- Build and return a slice of an array of type S overlaid on
4549 -- object Rec, with bounds specified by Lo and Hi. If either
4550 -- bound is empty, a default of S'First (respectively S'Last)
4557 function Build_Slice
4560 Hi
: Node_Id
) return Node_Id
4565 Opaque
: constant Node_Id
:=
4566 Unchecked_Convert_To
(Opaque_Type
,
4567 Make_Attribute_Reference
(Loc
,
4569 Attribute_Name
=> Name_Address
));
4570 -- Access value designating an opaque storage array of type
4571 -- S overlaid on record Rec.
4574 -- Compute slice bounds using S'First (1) and S'Last as
4575 -- default values when not specified by the caller.
4578 Lo_Bound
:= Make_Integer_Literal
(Loc
, 1);
4584 Hi_Bound
:= Make_Attribute_Reference
(Loc
,
4585 Prefix
=> New_Occurrence_Of
(Range_Type
, Loc
),
4586 Attribute_Name
=> Name_Last
);
4591 return Make_Slice
(Loc
,
4594 Discrete_Range
=> Make_Range
(Loc
,
4595 Lo_Bound
, Hi_Bound
));
4598 -- Start of processing for Controlled_Actions
4601 -- Create a constrained subtype of Storage_Array whose size
4602 -- corresponds to the value being assigned.
4604 -- subtype G is Storage_Offset range
4605 -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit
4607 Expr
:= Duplicate_Subexpr_No_Checks
(Expression
(N
));
4609 if Nkind
(Expr
) = N_Qualified_Expression
then
4610 Expr
:= Expression
(Expr
);
4613 Source_Actual_Subtype
:= Etype
(Expr
);
4615 if Has_Discriminants
(Source_Actual_Subtype
)
4616 and then not Is_Constrained
(Source_Actual_Subtype
)
4619 Build_Actual_Subtype
(Source_Actual_Subtype
, Expr
));
4620 Source_Actual_Subtype
:= Defining_Identifier
(Last
(Res
));
4626 Make_Attribute_Reference
(Loc
,
4628 New_Occurrence_Of
(Source_Actual_Subtype
, Loc
),
4629 Attribute_Name
=> Name_Size
),
4631 Make_Integer_Literal
(Loc
,
4632 Intval
=> System_Storage_Unit
- 1));
4635 Make_Op_Divide
(Loc
,
4636 Left_Opnd
=> Source_Size
,
4638 Make_Integer_Literal
(Loc
,
4639 Intval
=> System_Storage_Unit
));
4642 Make_Defining_Identifier
(Loc
,
4643 New_Internal_Name
('G'));
4646 Make_Subtype_Declaration
(Loc
,
4647 Defining_Identifier
=> Range_Type
,
4648 Subtype_Indication
=>
4649 Make_Subtype_Indication
(Loc
,
4651 New_Reference_To
(RTE
(RE_Storage_Offset
), Loc
),
4652 Constraint
=> Make_Range_Constraint
(Loc
,
4655 Low_Bound
=> Make_Integer_Literal
(Loc
, 1),
4656 High_Bound
=> Source_Size
)))));
4658 -- subtype S is Storage_Array (G)
4661 Make_Subtype_Declaration
(Loc
,
4662 Defining_Identifier
=>
4663 Make_Defining_Identifier
(Loc
,
4664 New_Internal_Name
('S')),
4665 Subtype_Indication
=>
4666 Make_Subtype_Indication
(Loc
,
4668 New_Reference_To
(RTE
(RE_Storage_Array
), Loc
),
4670 Make_Index_Or_Discriminant_Constraint
(Loc
,
4672 New_List
(New_Reference_To
(Range_Type
, Loc
))))));
4674 -- type A is access S
4677 Make_Defining_Identifier
(Loc
,
4678 Chars
=> New_Internal_Name
('A'));
4681 Make_Full_Type_Declaration
(Loc
,
4682 Defining_Identifier
=> Opaque_Type
,
4684 Make_Access_To_Object_Definition
(Loc
,
4685 Subtype_Indication
=>
4687 Defining_Identifier
(Last
(Res
)), Loc
))));
4689 -- Generate appropriate slice assignments
4691 First_After_Root
:= Make_Integer_Literal
(Loc
, 1);
4693 -- For controlled object, skip Root_Controlled part
4695 if Is_Controlled
(T
) then
4699 Make_Op_Divide
(Loc
,
4700 Make_Attribute_Reference
(Loc
,
4702 New_Occurrence_Of
(RTE
(RE_Root_Controlled
), Loc
),
4703 Attribute_Name
=> Name_Size
),
4704 Make_Integer_Literal
(Loc
, System_Storage_Unit
)));
4707 -- For the case of a record with controlled components, skip
4708 -- record controller Prev/Next components. These components
4709 -- constitute a 'hole' in the middle of the data to be copied.
4711 if Has_Controlled_Component
(T
) then
4713 Make_Selected_Component
(Loc
,
4715 Make_Selected_Component
(Loc
,
4716 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
4718 New_Reference_To
(Controller_Component
(T
), Loc
)),
4719 Selector_Name
=> Make_Identifier
(Loc
, Name_Prev
));
4721 -- Last index before hole: determined by position of the
4722 -- _Controller.Prev component.
4725 Make_Defining_Identifier
(Loc
,
4726 New_Internal_Name
('L'));
4729 Make_Object_Declaration
(Loc
,
4730 Defining_Identifier
=> Last_Before_Hole
,
4731 Object_Definition
=> New_Occurrence_Of
(
4732 RTE
(RE_Storage_Offset
), Loc
),
4733 Constant_Present
=> True,
4734 Expression
=> Make_Op_Add
(Loc
,
4735 Make_Attribute_Reference
(Loc
,
4737 Attribute_Name
=> Name_Position
),
4738 Make_Attribute_Reference
(Loc
,
4739 Prefix
=> New_Copy_Tree
(Prefix
(Prev_Ref
)),
4740 Attribute_Name
=> Name_Position
))));
4742 -- Hole length: size of the Prev and Next components
4745 Make_Op_Multiply
(Loc
,
4746 Left_Opnd
=> Make_Integer_Literal
(Loc
, Uint_2
),
4748 Make_Op_Divide
(Loc
,
4750 Make_Attribute_Reference
(Loc
,
4751 Prefix
=> New_Copy_Tree
(Prev_Ref
),
4752 Attribute_Name
=> Name_Size
),
4754 Make_Integer_Literal
(Loc
,
4755 Intval
=> System_Storage_Unit
)));
4757 -- First index after hole
4760 Make_Defining_Identifier
(Loc
,
4761 New_Internal_Name
('F'));
4764 Make_Object_Declaration
(Loc
,
4765 Defining_Identifier
=> First_After_Hole
,
4766 Object_Definition
=> New_Occurrence_Of
(
4767 RTE
(RE_Storage_Offset
), Loc
),
4768 Constant_Present
=> True,
4774 New_Occurrence_Of
(Last_Before_Hole
, Loc
),
4775 Right_Opnd
=> Hole_Length
),
4776 Right_Opnd
=> Make_Integer_Literal
(Loc
, 1))));
4779 New_Occurrence_Of
(Last_Before_Hole
, Loc
);
4781 New_Occurrence_Of
(First_After_Hole
, Loc
);
4784 -- Assign the first slice (possibly skipping Root_Controlled,
4785 -- up to the beginning of the record controller if present,
4786 -- up to the end of the object if not).
4788 Append_To
(Res
, Make_Assignment_Statement
(Loc
,
4789 Name
=> Build_Slice
(
4790 Rec
=> Duplicate_Subexpr_No_Checks
(L
),
4791 Lo
=> First_After_Root
,
4792 Hi
=> Last_Before_Hole
),
4794 Expression
=> Build_Slice
(
4795 Rec
=> Expression
(N
),
4796 Lo
=> First_After_Root
,
4797 Hi
=> New_Copy_Tree
(Last_Before_Hole
))));
4799 if Present
(First_After_Hole
) then
4801 -- If a record controller is present, copy the second slice,
4802 -- from right after the _Controller.Next component up to the
4803 -- end of the object.
4805 Append_To
(Res
, Make_Assignment_Statement
(Loc
,
4806 Name
=> Build_Slice
(
4807 Rec
=> Duplicate_Subexpr_No_Checks
(L
),
4808 Lo
=> First_After_Hole
,
4810 Expression
=> Build_Slice
(
4811 Rec
=> Duplicate_Subexpr_No_Checks
(Expression
(N
)),
4812 Lo
=> New_Copy_Tree
(First_After_Hole
),
4815 end Controlled_Actions
;
4818 -- Not controlled case
4822 Asn
: constant Node_Id
:= Relocate_Node
(N
);
4825 -- If this is the case of a tagged type with a full rep clause,
4826 -- we must expand it into component assignments, so we mark the
4827 -- node as unanalyzed, to get it reanalyzed, but flag it has
4828 -- requiring component-wise assignment so we don't get infinite
4831 if Component_Assign
then
4832 Set_Analyzed
(Asn
, False);
4833 Set_Componentwise_Assignment
(Asn
, True);
4836 Append_To
(Res
, Asn
);
4844 Make_Assignment_Statement
(Loc
,
4846 Make_Selected_Component
(Loc
,
4847 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
4848 Selector_Name
=> New_Reference_To
(First_Tag_Component
(T
),
4850 Expression
=> New_Reference_To
(Tag_Tmp
, Loc
)));
4854 if VM_Target
/= No_VM
then
4855 -- Restore the finalization pointers
4858 Make_Assignment_Statement
(Loc
,
4860 Make_Selected_Component
(Loc
,
4862 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
4863 New_Copy_Tree
(Ctrl_Ref
)),
4864 Selector_Name
=> Make_Identifier
(Loc
, Name_Prev
)),
4865 Expression
=> New_Reference_To
(Prev_Tmp
, Loc
)));
4868 Make_Assignment_Statement
(Loc
,
4870 Make_Selected_Component
(Loc
,
4872 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
4873 New_Copy_Tree
(Ctrl_Ref
)),
4874 Selector_Name
=> Make_Identifier
(Loc
, Name_Next
)),
4875 Expression
=> New_Reference_To
(Next_Tmp
, Loc
)));
4878 -- Adjust the target after the assignment when controlled (not in the
4879 -- init proc since it is an initialization more than an assignment).
4881 Append_List_To
(Res
,
4883 Ref
=> Duplicate_Subexpr_Move_Checks
(L
),
4885 Flist_Ref
=> New_Reference_To
(RTE
(RE_Global_Final_List
), Loc
),
4886 With_Attach
=> Make_Integer_Literal
(Loc
, 0)));
4892 -- Could use comment here ???
4894 when RE_Not_Available
=>
4896 end Make_Tag_Ctrl_Assignment
;