1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2016, 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 Aspects
; use Aspects
;
27 with Atree
; use Atree
;
28 with Checks
; use Checks
;
29 with Debug
; use Debug
;
30 with Einfo
; use Einfo
;
31 with Elists
; use Elists
;
32 with Errout
; use Errout
;
33 with Exp_Aggr
; use Exp_Aggr
;
34 with Exp_Ch6
; use Exp_Ch6
;
35 with Exp_Ch7
; use Exp_Ch7
;
36 with Exp_Ch11
; use Exp_Ch11
;
37 with Exp_Dbug
; use Exp_Dbug
;
38 with Exp_Pakd
; use Exp_Pakd
;
39 with Exp_Tss
; use Exp_Tss
;
40 with Exp_Util
; use Exp_Util
;
41 with Ghost
; use Ghost
;
42 with Inline
; use Inline
;
43 with Namet
; use Namet
;
44 with Nlists
; use Nlists
;
45 with Nmake
; use Nmake
;
47 with Restrict
; use Restrict
;
48 with Rident
; use Rident
;
49 with Rtsfind
; use Rtsfind
;
50 with Sinfo
; use Sinfo
;
52 with Sem_Aux
; use Sem_Aux
;
53 with Sem_Ch3
; use Sem_Ch3
;
54 with Sem_Ch8
; use Sem_Ch8
;
55 with Sem_Ch13
; use Sem_Ch13
;
56 with Sem_Eval
; use Sem_Eval
;
57 with Sem_Res
; use Sem_Res
;
58 with Sem_Util
; use Sem_Util
;
59 with Snames
; use Snames
;
60 with Stand
; use Stand
;
61 with Stringt
; use Stringt
;
62 with Tbuild
; use Tbuild
;
63 with Uintp
; use Uintp
;
64 with Validsw
; use Validsw
;
66 package body Exp_Ch5
is
68 procedure Build_Formal_Container_Iteration
70 Container
: Entity_Id
;
73 Advance
: out Node_Id
;
74 New_Loop
: out Node_Id
);
75 -- Utility to create declarations and loop statement for both forms
76 -- of formal container iterators.
78 function Change_Of_Representation
(N
: Node_Id
) return Boolean;
79 -- Determine if the right hand side of assignment N is a type conversion
80 -- which requires a change of representation. Called only for the array
83 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
);
84 -- N is an assignment which assigns an array value. This routine process
85 -- the various special cases and checks required for such assignments,
86 -- including change of representation. Rhs is normally simply the right
87 -- hand side of the assignment, except that if the right hand side is a
88 -- type conversion or a qualified expression, then the RHS is the actual
89 -- expression inside any such type conversions or qualifications.
91 function Expand_Assign_Array_Loop
98 Rev
: Boolean) return Node_Id
;
99 -- N is an assignment statement which assigns an array value. This routine
100 -- expands the assignment into a loop (or nested loops for the case of a
101 -- multi-dimensional array) to do the assignment component by component.
102 -- Larray and Rarray are the entities of the actual arrays on the left
103 -- hand and right hand sides. L_Type and R_Type are the types of these
104 -- arrays (which may not be the same, due to either sliding, or to a
105 -- change of representation case). Ndim is the number of dimensions and
106 -- the parameter Rev indicates if the loops run normally (Rev = False),
107 -- or reversed (Rev = True). The value returned is the constructed
108 -- loop statement. Auxiliary declarations are inserted before node N
109 -- using the standard Insert_Actions mechanism.
111 procedure Expand_Assign_Record
(N
: Node_Id
);
112 -- N is an assignment of an untagged record value. This routine handles
113 -- the case where the assignment must be made component by component,
114 -- either because the target is not byte aligned, or there is a change
115 -- of representation, or when we have a tagged type with a representation
116 -- clause (this last case is required because holes in the tagged type
117 -- might be filled with components from child types).
119 procedure Expand_Formal_Container_Loop
(N
: Node_Id
);
120 -- Use the primitives specified in an Iterable aspect to expand a loop
121 -- over a so-called formal container, primarily for SPARK usage.
123 procedure Expand_Formal_Container_Element_Loop
(N
: Node_Id
);
124 -- Same, for an iterator of the form " For E of C". In this case the
125 -- iterator provides the name of the element, and the cursor is generated
128 procedure Expand_Iterator_Loop
(N
: Node_Id
);
129 -- Expand loop over arrays and containers that uses the form "for X of C"
130 -- with an optional subtype mark, or "for Y in C".
132 procedure Expand_Iterator_Loop_Over_Container
137 Container_Typ
: Entity_Id
);
138 -- Expand loop over containers that uses the form "for X of C" with an
139 -- optional subtype mark, or "for Y in C". Isc is the iteration scheme.
140 -- I_Spec is the iterator specification and Container is either the
141 -- Container (for OF) or the iterator (for IN).
143 procedure Expand_Predicated_Loop
(N
: Node_Id
);
144 -- Expand for loop over predicated subtype
146 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
;
147 -- Generate the necessary code for controlled and tagged assignment, that
148 -- is to say, finalization of the target before, adjustment of the target
149 -- after and save and restore of the tag and finalization pointers which
150 -- are not 'part of the value' and must not be changed upon assignment. N
151 -- is the original Assignment node.
153 --------------------------------------
154 -- Build_Formal_Container_iteration --
155 --------------------------------------
157 procedure Build_Formal_Container_Iteration
159 Container
: Entity_Id
;
162 Advance
: out Node_Id
;
163 New_Loop
: out Node_Id
)
165 Loc
: constant Source_Ptr
:= Sloc
(N
);
166 Stats
: constant List_Id
:= Statements
(N
);
167 Typ
: constant Entity_Id
:= Base_Type
(Etype
(Container
));
168 First_Op
: constant Entity_Id
:=
169 Get_Iterable_Type_Primitive
(Typ
, Name_First
);
170 Next_Op
: constant Entity_Id
:=
171 Get_Iterable_Type_Primitive
(Typ
, Name_Next
);
173 Has_Element_Op
: constant Entity_Id
:=
174 Get_Iterable_Type_Primitive
(Typ
, Name_Has_Element
);
176 -- Declaration for Cursor
179 Make_Object_Declaration
(Loc
,
180 Defining_Identifier
=> Cursor
,
181 Object_Definition
=> New_Occurrence_Of
(Etype
(First_Op
), Loc
),
183 Make_Function_Call
(Loc
,
184 Name
=> New_Occurrence_Of
(First_Op
, Loc
),
185 Parameter_Associations
=> New_List
(
186 New_Occurrence_Of
(Container
, Loc
))));
188 -- Statement that advances cursor in loop
191 Make_Assignment_Statement
(Loc
,
192 Name
=> New_Occurrence_Of
(Cursor
, Loc
),
194 Make_Function_Call
(Loc
,
195 Name
=> New_Occurrence_Of
(Next_Op
, Loc
),
196 Parameter_Associations
=> New_List
(
197 New_Occurrence_Of
(Container
, Loc
),
198 New_Occurrence_Of
(Cursor
, Loc
))));
200 -- Iterator is rewritten as a while_loop
203 Make_Loop_Statement
(Loc
,
205 Make_Iteration_Scheme
(Loc
,
207 Make_Function_Call
(Loc
,
208 Name
=> New_Occurrence_Of
(Has_Element_Op
, Loc
),
209 Parameter_Associations
=> New_List
(
210 New_Occurrence_Of
(Container
, Loc
),
211 New_Occurrence_Of
(Cursor
, Loc
)))),
214 end Build_Formal_Container_Iteration
;
216 ------------------------------
217 -- Change_Of_Representation --
218 ------------------------------
220 function Change_Of_Representation
(N
: Node_Id
) return Boolean is
221 Rhs
: constant Node_Id
:= Expression
(N
);
224 Nkind
(Rhs
) = N_Type_Conversion
226 not Same_Representation
(Etype
(Rhs
), Etype
(Expression
(Rhs
)));
227 end Change_Of_Representation
;
229 -------------------------
230 -- Expand_Assign_Array --
231 -------------------------
233 -- There are two issues here. First, do we let Gigi do a block move, or
234 -- do we expand out into a loop? Second, we need to set the two flags
235 -- Forwards_OK and Backwards_OK which show whether the block move (or
236 -- corresponding loops) can be legitimately done in a forwards (low to
237 -- high) or backwards (high to low) manner.
239 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
) is
240 Loc
: constant Source_Ptr
:= Sloc
(N
);
242 Lhs
: constant Node_Id
:= Name
(N
);
244 Act_Lhs
: constant Node_Id
:= Get_Referenced_Object
(Lhs
);
245 Act_Rhs
: Node_Id
:= Get_Referenced_Object
(Rhs
);
247 L_Type
: constant Entity_Id
:=
248 Underlying_Type
(Get_Actual_Subtype
(Act_Lhs
));
249 R_Type
: Entity_Id
:=
250 Underlying_Type
(Get_Actual_Subtype
(Act_Rhs
));
252 L_Slice
: constant Boolean := Nkind
(Act_Lhs
) = N_Slice
;
253 R_Slice
: constant Boolean := Nkind
(Act_Rhs
) = N_Slice
;
255 Crep
: constant Boolean := Change_Of_Representation
(N
);
260 Ndim
: constant Pos
:= Number_Dimensions
(L_Type
);
262 Loop_Required
: Boolean := False;
263 -- This switch is set to True if the array move must be done using
264 -- an explicit front end generated loop.
266 procedure Apply_Dereference
(Arg
: Node_Id
);
267 -- If the argument is an access to an array, and the assignment is
268 -- converted into a procedure call, apply explicit dereference.
270 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean;
271 -- Test if Exp is a reference to an array whose declaration has
272 -- an address clause, or it is a slice of such an array.
274 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean;
275 -- Test if Exp is a reference to an array which is either a formal
276 -- parameter or a slice of a formal parameter. These are the cases
277 -- where hidden aliasing can occur.
279 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean;
280 -- Determine if Exp is a reference to an array variable which is other
281 -- than an object defined in the current scope, or a slice of such
282 -- an object. Such objects can be aliased to parameters (unlike local
283 -- array references).
285 -----------------------
286 -- Apply_Dereference --
287 -----------------------
289 procedure Apply_Dereference
(Arg
: Node_Id
) is
290 Typ
: constant Entity_Id
:= Etype
(Arg
);
292 if Is_Access_Type
(Typ
) then
293 Rewrite
(Arg
, Make_Explicit_Dereference
(Loc
,
294 Prefix
=> Relocate_Node
(Arg
)));
295 Analyze_And_Resolve
(Arg
, Designated_Type
(Typ
));
297 end Apply_Dereference
;
299 ------------------------
300 -- Has_Address_Clause --
301 ------------------------
303 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean is
306 (Is_Entity_Name
(Exp
) and then
307 Present
(Address_Clause
(Entity
(Exp
))))
309 (Nkind
(Exp
) = N_Slice
and then Has_Address_Clause
(Prefix
(Exp
)));
310 end Has_Address_Clause
;
312 ---------------------
313 -- Is_Formal_Array --
314 ---------------------
316 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean is
319 (Is_Entity_Name
(Exp
) and then Is_Formal
(Entity
(Exp
)))
321 (Nkind
(Exp
) = N_Slice
and then Is_Formal_Array
(Prefix
(Exp
)));
324 ------------------------
325 -- Is_Non_Local_Array --
326 ------------------------
328 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean is
330 return (Is_Entity_Name
(Exp
)
331 and then Scope
(Entity
(Exp
)) /= Current_Scope
)
332 or else (Nkind
(Exp
) = N_Slice
333 and then Is_Non_Local_Array
(Prefix
(Exp
)));
334 end Is_Non_Local_Array
;
336 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
338 Lhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Lhs
);
339 Rhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Rhs
);
341 Lhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Lhs
);
342 Rhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Rhs
);
344 -- Start of processing for Expand_Assign_Array
347 -- Deal with length check. Note that the length check is done with
348 -- respect to the right hand side as given, not a possible underlying
349 -- renamed object, since this would generate incorrect extra checks.
351 Apply_Length_Check
(Rhs
, L_Type
);
353 -- We start by assuming that the move can be done in either direction,
354 -- i.e. that the two sides are completely disjoint.
356 Set_Forwards_OK
(N
, True);
357 Set_Backwards_OK
(N
, True);
359 -- Normally it is only the slice case that can lead to overlap, and
360 -- explicit checks for slices are made below. But there is one case
361 -- where the slice can be implicit and invisible to us: when we have a
362 -- one dimensional array, and either both operands are parameters, or
363 -- one is a parameter (which can be a slice passed by reference) and the
364 -- other is a non-local variable. In this case the parameter could be a
365 -- slice that overlaps with the other operand.
367 -- However, if the array subtype is a constrained first subtype in the
368 -- parameter case, then we don't have to worry about overlap, since
369 -- slice assignments aren't possible (other than for a slice denoting
372 -- Note: No overlap is possible if there is a change of representation,
373 -- so we can exclude this case.
378 ((Lhs_Formal
and Rhs_Formal
)
380 (Lhs_Formal
and Rhs_Non_Local_Var
)
382 (Rhs_Formal
and Lhs_Non_Local_Var
))
384 (not Is_Constrained
(Etype
(Lhs
))
385 or else not Is_First_Subtype
(Etype
(Lhs
)))
387 Set_Forwards_OK
(N
, False);
388 Set_Backwards_OK
(N
, False);
390 -- Note: the bit-packed case is not worrisome here, since if we have
391 -- a slice passed as a parameter, it is always aligned on a byte
392 -- boundary, and if there are no explicit slices, the assignment
393 -- can be performed directly.
396 -- If either operand has an address clause clear Backwards_OK and
397 -- Forwards_OK, since we cannot tell if the operands overlap. We
398 -- exclude this treatment when Rhs is an aggregate, since we know
399 -- that overlap can't occur.
401 if (Has_Address_Clause
(Lhs
) and then Nkind
(Rhs
) /= N_Aggregate
)
402 or else Has_Address_Clause
(Rhs
)
404 Set_Forwards_OK
(N
, False);
405 Set_Backwards_OK
(N
, False);
408 -- We certainly must use a loop for change of representation and also
409 -- we use the operand of the conversion on the right hand side as the
410 -- effective right hand side (the component types must match in this
414 Act_Rhs
:= Get_Referenced_Object
(Rhs
);
415 R_Type
:= Get_Actual_Subtype
(Act_Rhs
);
416 Loop_Required
:= True;
418 -- We require a loop if the left side is possibly bit unaligned
420 elsif Possible_Bit_Aligned_Component
(Lhs
)
422 Possible_Bit_Aligned_Component
(Rhs
)
424 Loop_Required
:= True;
426 -- Arrays with controlled components are expanded into a loop to force
427 -- calls to Adjust at the component level.
429 elsif Has_Controlled_Component
(L_Type
) then
430 Loop_Required
:= True;
432 -- If object is atomic/VFA, we cannot tolerate a loop
434 elsif Is_Atomic_Or_VFA_Object
(Act_Lhs
)
436 Is_Atomic_Or_VFA_Object
(Act_Rhs
)
440 -- Loop is required if we have atomic components since we have to
441 -- be sure to do any accesses on an element by element basis.
443 elsif Has_Atomic_Components
(L_Type
)
444 or else Has_Atomic_Components
(R_Type
)
445 or else Is_Atomic_Or_VFA
(Component_Type
(L_Type
))
446 or else Is_Atomic_Or_VFA
(Component_Type
(R_Type
))
448 Loop_Required
:= True;
450 -- Case where no slice is involved
452 elsif not L_Slice
and not R_Slice
then
454 -- The following code deals with the case of unconstrained bit packed
455 -- arrays. The problem is that the template for such arrays contains
456 -- the bounds of the actual source level array, but the copy of an
457 -- entire array requires the bounds of the underlying array. It would
458 -- be nice if the back end could take care of this, but right now it
459 -- does not know how, so if we have such a type, then we expand out
460 -- into a loop, which is inefficient but works correctly. If we don't
461 -- do this, we get the wrong length computed for the array to be
462 -- moved. The two cases we need to worry about are:
464 -- Explicit dereference of an unconstrained packed array type as in
465 -- the following example:
468 -- type BITS is array(INTEGER range <>) of BOOLEAN;
469 -- pragma PACK(BITS);
470 -- type A is access BITS;
473 -- P1 := new BITS (1 .. 65_535);
474 -- P2 := new BITS (1 .. 65_535);
478 -- A formal parameter reference with an unconstrained bit array type
479 -- is the other case we need to worry about (here we assume the same
480 -- BITS type declared above):
482 -- procedure Write_All (File : out BITS; Contents : BITS);
484 -- File.Storage := Contents;
487 -- We expand to a loop in either of these two cases
489 -- Question for future thought. Another potentially more efficient
490 -- approach would be to create the actual subtype, and then do an
491 -- unchecked conversion to this actual subtype ???
493 Check_Unconstrained_Bit_Packed_Array
: declare
495 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean;
496 -- Function to perform required test for the first case, above
497 -- (dereference of an unconstrained bit packed array).
499 -----------------------
500 -- Is_UBPA_Reference --
501 -----------------------
503 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean is
504 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Opnd
));
506 Des_Type
: Entity_Id
;
509 if Present
(Packed_Array_Impl_Type
(Typ
))
510 and then Is_Array_Type
(Packed_Array_Impl_Type
(Typ
))
511 and then not Is_Constrained
(Packed_Array_Impl_Type
(Typ
))
515 elsif Nkind
(Opnd
) = N_Explicit_Dereference
then
516 P_Type
:= Underlying_Type
(Etype
(Prefix
(Opnd
)));
518 if not Is_Access_Type
(P_Type
) then
522 Des_Type
:= Designated_Type
(P_Type
);
524 Is_Bit_Packed_Array
(Des_Type
)
525 and then not Is_Constrained
(Des_Type
);
531 end Is_UBPA_Reference
;
533 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
536 if Is_UBPA_Reference
(Lhs
)
538 Is_UBPA_Reference
(Rhs
)
540 Loop_Required
:= True;
542 -- Here if we do not have the case of a reference to a bit packed
543 -- unconstrained array case. In this case gigi can most certainly
544 -- handle the assignment if a forwards move is allowed.
546 -- (could it handle the backwards case also???)
548 elsif Forwards_OK
(N
) then
551 end Check_Unconstrained_Bit_Packed_Array
;
553 -- The back end can always handle the assignment if the right side is a
554 -- string literal (note that overlap is definitely impossible in this
555 -- case). If the type is packed, a string literal is always converted
556 -- into an aggregate, except in the case of a null slice, for which no
557 -- aggregate can be written. In that case, rewrite the assignment as a
558 -- null statement, a length check has already been emitted to verify
559 -- that the range of the left-hand side is empty.
561 -- Note that this code is not executed if we have an assignment of a
562 -- string literal to a non-bit aligned component of a record, a case
563 -- which cannot be handled by the backend.
565 elsif Nkind
(Rhs
) = N_String_Literal
then
566 if String_Length
(Strval
(Rhs
)) = 0
567 and then Is_Bit_Packed_Array
(L_Type
)
569 Rewrite
(N
, Make_Null_Statement
(Loc
));
575 -- If either operand is bit packed, then we need a loop, since we can't
576 -- be sure that the slice is byte aligned. Similarly, if either operand
577 -- is a possibly unaligned slice, then we need a loop (since the back
578 -- end cannot handle unaligned slices).
580 elsif Is_Bit_Packed_Array
(L_Type
)
581 or else Is_Bit_Packed_Array
(R_Type
)
582 or else Is_Possibly_Unaligned_Slice
(Lhs
)
583 or else Is_Possibly_Unaligned_Slice
(Rhs
)
585 Loop_Required
:= True;
587 -- If we are not bit-packed, and we have only one slice, then no overlap
588 -- is possible except in the parameter case, so we can let the back end
591 elsif not (L_Slice
and R_Slice
) then
592 if Forwards_OK
(N
) then
597 -- If the right-hand side is a string literal, introduce a temporary for
598 -- it, for use in the generated loop that will follow.
600 if Nkind
(Rhs
) = N_String_Literal
then
602 Temp
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T', Rhs
);
607 Make_Object_Declaration
(Loc
,
608 Defining_Identifier
=> Temp
,
609 Object_Definition
=> New_Occurrence_Of
(L_Type
, Loc
),
610 Expression
=> Relocate_Node
(Rhs
));
612 Insert_Action
(N
, Decl
);
613 Rewrite
(Rhs
, New_Occurrence_Of
(Temp
, Loc
));
614 R_Type
:= Etype
(Temp
);
618 -- Come here to complete the analysis
620 -- Loop_Required: Set to True if we know that a loop is required
621 -- regardless of overlap considerations.
623 -- Forwards_OK: Set to False if we already know that a forwards
624 -- move is not safe, else set to True.
626 -- Backwards_OK: Set to False if we already know that a backwards
627 -- move is not safe, else set to True
629 -- Our task at this stage is to complete the overlap analysis, which can
630 -- result in possibly setting Forwards_OK or Backwards_OK to False, and
631 -- then generating the final code, either by deciding that it is OK
632 -- after all to let Gigi handle it, or by generating appropriate code
636 L_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(L_Type
));
637 R_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(R_Type
));
639 Left_Lo
: constant Node_Id
:= Type_Low_Bound
(L_Index_Typ
);
640 Left_Hi
: constant Node_Id
:= Type_High_Bound
(L_Index_Typ
);
641 Right_Lo
: constant Node_Id
:= Type_Low_Bound
(R_Index_Typ
);
642 Right_Hi
: constant Node_Id
:= Type_High_Bound
(R_Index_Typ
);
644 Act_L_Array
: Node_Id
;
645 Act_R_Array
: Node_Id
;
651 Cresult
: Compare_Result
;
654 -- Get the expressions for the arrays. If we are dealing with a
655 -- private type, then convert to the underlying type. We can do
656 -- direct assignments to an array that is a private type, but we
657 -- cannot assign to elements of the array without this extra
658 -- unchecked conversion.
660 -- Note: We propagate Parent to the conversion nodes to generate
661 -- a well-formed subtree.
663 if Nkind
(Act_Lhs
) = N_Slice
then
664 Larray
:= Prefix
(Act_Lhs
);
668 if Is_Private_Type
(Etype
(Larray
)) then
670 Par
: constant Node_Id
:= Parent
(Larray
);
674 (Underlying_Type
(Etype
(Larray
)), Larray
);
675 Set_Parent
(Larray
, Par
);
680 if Nkind
(Act_Rhs
) = N_Slice
then
681 Rarray
:= Prefix
(Act_Rhs
);
685 if Is_Private_Type
(Etype
(Rarray
)) then
687 Par
: constant Node_Id
:= Parent
(Rarray
);
691 (Underlying_Type
(Etype
(Rarray
)), Rarray
);
692 Set_Parent
(Rarray
, Par
);
697 -- If both sides are slices, we must figure out whether it is safe
698 -- to do the move in one direction or the other. It is always safe
699 -- if there is a change of representation since obviously two arrays
700 -- with different representations cannot possibly overlap.
702 if (not Crep
) and L_Slice
and R_Slice
then
703 Act_L_Array
:= Get_Referenced_Object
(Prefix
(Act_Lhs
));
704 Act_R_Array
:= Get_Referenced_Object
(Prefix
(Act_Rhs
));
706 -- If both left and right hand arrays are entity names, and refer
707 -- to different entities, then we know that the move is safe (the
708 -- two storage areas are completely disjoint).
710 if Is_Entity_Name
(Act_L_Array
)
711 and then Is_Entity_Name
(Act_R_Array
)
712 and then Entity
(Act_L_Array
) /= Entity
(Act_R_Array
)
716 -- Otherwise, we assume the worst, which is that the two arrays
717 -- are the same array. There is no need to check if we know that
718 -- is the case, because if we don't know it, we still have to
721 -- Generally if the same array is involved, then we have an
722 -- overlapping case. We will have to really assume the worst (i.e.
723 -- set neither of the OK flags) unless we can determine the lower
724 -- or upper bounds at compile time and compare them.
729 (Left_Lo
, Right_Lo
, Assume_Valid
=> True);
731 if Cresult
= Unknown
then
734 (Left_Hi
, Right_Hi
, Assume_Valid
=> True);
738 when LT | LE | EQ
=> Set_Backwards_OK
(N
, False);
739 when GT | GE
=> Set_Forwards_OK
(N
, False);
740 when NE | Unknown
=> Set_Backwards_OK
(N
, False);
741 Set_Forwards_OK
(N
, False);
746 -- If after that analysis Loop_Required is False, meaning that we
747 -- have not discovered some non-overlap reason for requiring a loop,
748 -- then the outcome depends on the capabilities of the back end.
750 if not Loop_Required
then
751 -- Assume the back end can deal with all cases of overlap by
752 -- falling back to memmove if it cannot use a more efficient
758 -- At this stage we have to generate an explicit loop, and we have
759 -- the following cases:
761 -- Forwards_OK = True
763 -- Rnn : right_index := right_index'First;
764 -- for Lnn in left-index loop
765 -- left (Lnn) := right (Rnn);
766 -- Rnn := right_index'Succ (Rnn);
769 -- Note: the above code MUST be analyzed with checks off, because
770 -- otherwise the Succ could overflow. But in any case this is more
773 -- Forwards_OK = False, Backwards_OK = True
775 -- Rnn : right_index := right_index'Last;
776 -- for Lnn in reverse left-index loop
777 -- left (Lnn) := right (Rnn);
778 -- Rnn := right_index'Pred (Rnn);
781 -- Note: the above code MUST be analyzed with checks off, because
782 -- otherwise the Pred could overflow. But in any case this is more
785 -- Forwards_OK = Backwards_OK = False
787 -- This only happens if we have the same array on each side. It is
788 -- possible to create situations using overlays that violate this,
789 -- but we simply do not promise to get this "right" in this case.
791 -- There are two possible subcases. If the No_Implicit_Conditionals
792 -- restriction is set, then we generate the following code:
795 -- T : constant <operand-type> := rhs;
800 -- If implicit conditionals are permitted, then we generate:
802 -- if Left_Lo <= Right_Lo then
803 -- <code for Forwards_OK = True above>
805 -- <code for Backwards_OK = True above>
808 -- In order to detect possible aliasing, we examine the renamed
809 -- expression when the source or target is a renaming. However,
810 -- the renaming may be intended to capture an address that may be
811 -- affected by subsequent code, and therefore we must recover
812 -- the actual entity for the expansion that follows, not the
813 -- object it renames. In particular, if source or target designate
814 -- a portion of a dynamically allocated object, the pointer to it
815 -- may be reassigned but the renaming preserves the proper location.
817 if Is_Entity_Name
(Rhs
)
819 Nkind
(Parent
(Entity
(Rhs
))) = N_Object_Renaming_Declaration
820 and then Nkind
(Act_Rhs
) = N_Slice
825 if Is_Entity_Name
(Lhs
)
827 Nkind
(Parent
(Entity
(Lhs
))) = N_Object_Renaming_Declaration
828 and then Nkind
(Act_Lhs
) = N_Slice
833 -- Cases where either Forwards_OK or Backwards_OK is true
835 if Forwards_OK
(N
) or else Backwards_OK
(N
) then
836 if Needs_Finalization
(Component_Type
(L_Type
))
837 and then Base_Type
(L_Type
) = Base_Type
(R_Type
)
839 and then not No_Ctrl_Actions
(N
)
842 Proc
: constant Entity_Id
:=
843 TSS
(Base_Type
(L_Type
), TSS_Slice_Assign
);
847 Apply_Dereference
(Larray
);
848 Apply_Dereference
(Rarray
);
849 Actuals
:= New_List
(
850 Duplicate_Subexpr
(Larray
, Name_Req
=> True),
851 Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
852 Duplicate_Subexpr
(Left_Lo
, Name_Req
=> True),
853 Duplicate_Subexpr
(Left_Hi
, Name_Req
=> True),
854 Duplicate_Subexpr
(Right_Lo
, Name_Req
=> True),
855 Duplicate_Subexpr
(Right_Hi
, Name_Req
=> True));
859 Boolean_Literals
(not Forwards_OK
(N
)), Loc
));
862 Make_Procedure_Call_Statement
(Loc
,
863 Name
=> New_Occurrence_Of
(Proc
, Loc
),
864 Parameter_Associations
=> Actuals
));
869 Expand_Assign_Array_Loop
870 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
871 Rev
=> not Forwards_OK
(N
)));
874 -- Case of both are false with No_Implicit_Conditionals
876 elsif Restriction_Active
(No_Implicit_Conditionals
) then
878 T
: constant Entity_Id
:=
879 Make_Defining_Identifier
(Loc
, Chars
=> Name_T
);
883 Make_Block_Statement
(Loc
,
884 Declarations
=> New_List
(
885 Make_Object_Declaration
(Loc
,
886 Defining_Identifier
=> T
,
887 Constant_Present
=> True,
889 New_Occurrence_Of
(Etype
(Rhs
), Loc
),
890 Expression
=> Relocate_Node
(Rhs
))),
892 Handled_Statement_Sequence
=>
893 Make_Handled_Sequence_Of_Statements
(Loc
,
894 Statements
=> New_List
(
895 Make_Assignment_Statement
(Loc
,
896 Name
=> Relocate_Node
(Lhs
),
897 Expression
=> New_Occurrence_Of
(T
, Loc
))))));
900 -- Case of both are false with implicit conditionals allowed
903 -- Before we generate this code, we must ensure that the left and
904 -- right side array types are defined. They may be itypes, and we
905 -- cannot let them be defined inside the if, since the first use
906 -- in the then may not be executed.
908 Ensure_Defined
(L_Type
, N
);
909 Ensure_Defined
(R_Type
, N
);
911 -- We normally compare addresses to find out which way round to
912 -- do the loop, since this is reliable, and handles the cases of
913 -- parameters, conversions etc. But we can't do that in the bit
914 -- packed case, because addresses don't work there.
916 if not Is_Bit_Packed_Array
(L_Type
) then
920 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
921 Make_Attribute_Reference
(Loc
,
923 Make_Indexed_Component
(Loc
,
925 Duplicate_Subexpr_Move_Checks
(Larray
, True),
926 Expressions
=> New_List
(
927 Make_Attribute_Reference
(Loc
,
931 Attribute_Name
=> Name_First
))),
932 Attribute_Name
=> Name_Address
)),
935 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
936 Make_Attribute_Reference
(Loc
,
938 Make_Indexed_Component
(Loc
,
940 Duplicate_Subexpr_Move_Checks
(Rarray
, True),
941 Expressions
=> New_List
(
942 Make_Attribute_Reference
(Loc
,
946 Attribute_Name
=> Name_First
))),
947 Attribute_Name
=> Name_Address
)));
949 -- For the bit packed and VM cases we use the bounds. That's OK,
950 -- because we don't have to worry about parameters, since they
951 -- cannot cause overlap. Perhaps we should worry about weird slice
957 Cleft_Lo
:= New_Copy_Tree
(Left_Lo
);
958 Cright_Lo
:= New_Copy_Tree
(Right_Lo
);
960 -- If the types do not match we add an implicit conversion
961 -- here to ensure proper match
963 if Etype
(Left_Lo
) /= Etype
(Right_Lo
) then
965 Unchecked_Convert_To
(Etype
(Left_Lo
), Cright_Lo
);
968 -- Reset the Analyzed flag, because the bounds of the index
969 -- type itself may be universal, and must must be reanalyzed
970 -- to acquire the proper type for the back end.
972 Set_Analyzed
(Cleft_Lo
, False);
973 Set_Analyzed
(Cright_Lo
, False);
977 Left_Opnd
=> Cleft_Lo
,
978 Right_Opnd
=> Cright_Lo
);
981 if Needs_Finalization
(Component_Type
(L_Type
))
982 and then Base_Type
(L_Type
) = Base_Type
(R_Type
)
984 and then not No_Ctrl_Actions
(N
)
987 -- Call TSS procedure for array assignment, passing the
988 -- explicit bounds of right and left hand sides.
991 Proc
: constant Entity_Id
:=
992 TSS
(Base_Type
(L_Type
), TSS_Slice_Assign
);
996 Apply_Dereference
(Larray
);
997 Apply_Dereference
(Rarray
);
998 Actuals
:= New_List
(
999 Duplicate_Subexpr
(Larray
, Name_Req
=> True),
1000 Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
1001 Duplicate_Subexpr
(Left_Lo
, Name_Req
=> True),
1002 Duplicate_Subexpr
(Left_Hi
, Name_Req
=> True),
1003 Duplicate_Subexpr
(Right_Lo
, Name_Req
=> True),
1004 Duplicate_Subexpr
(Right_Hi
, Name_Req
=> True));
1008 Right_Opnd
=> Condition
));
1011 Make_Procedure_Call_Statement
(Loc
,
1012 Name
=> New_Occurrence_Of
(Proc
, Loc
),
1013 Parameter_Associations
=> Actuals
));
1018 Make_Implicit_If_Statement
(N
,
1019 Condition
=> Condition
,
1021 Then_Statements
=> New_List
(
1022 Expand_Assign_Array_Loop
1023 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
1026 Else_Statements
=> New_List
(
1027 Expand_Assign_Array_Loop
1028 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
1033 Analyze
(N
, Suppress
=> All_Checks
);
1037 when RE_Not_Available
=>
1039 end Expand_Assign_Array
;
1041 ------------------------------
1042 -- Expand_Assign_Array_Loop --
1043 ------------------------------
1045 -- The following is an example of the loop generated for the case of a
1046 -- two-dimensional array:
1049 -- R2b : Tm1X1 := 1;
1051 -- for L1b in 1 .. 100 loop
1053 -- R4b : Tm1X2 := 1;
1055 -- for L3b in 1 .. 100 loop
1056 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
1057 -- R4b := Tm1X2'succ(R4b);
1060 -- R2b := Tm1X1'succ(R2b);
1064 -- Here Rev is False, and Tm1Xn are the subscript types for the right hand
1065 -- side. The declarations of R2b and R4b are inserted before the original
1066 -- assignment statement.
1068 function Expand_Assign_Array_Loop
1075 Rev
: Boolean) return Node_Id
1077 Loc
: constant Source_Ptr
:= Sloc
(N
);
1079 Lnn
: array (1 .. Ndim
) of Entity_Id
;
1080 Rnn
: array (1 .. Ndim
) of Entity_Id
;
1081 -- Entities used as subscripts on left and right sides
1083 L_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
1084 R_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
1085 -- Left and right index types
1092 function Build_Step
(J
: Nat
) return Node_Id
;
1093 -- The increment step for the index of the right-hand side is written
1094 -- as an attribute reference (Succ or Pred). This function returns
1095 -- the corresponding node, which is placed at the end of the loop body.
1101 function Build_Step
(J
: Nat
) return Node_Id
is
1113 Make_Assignment_Statement
(Loc
,
1114 Name
=> New_Occurrence_Of
(Rnn
(J
), Loc
),
1116 Make_Attribute_Reference
(Loc
,
1118 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1119 Attribute_Name
=> S_Or_P
,
1120 Expressions
=> New_List
(
1121 New_Occurrence_Of
(Rnn
(J
), Loc
))));
1123 -- Note that on the last iteration of the loop, the index is increased
1124 -- (or decreased) past the corresponding bound. This is consistent with
1125 -- the C semantics of the back-end, where such an off-by-one value on a
1126 -- dead index variable is OK. However, in CodePeer mode this leads to
1127 -- spurious warnings, and thus we place a guard around the attribute
1128 -- reference. For obvious reasons we only do this for CodePeer.
1130 if CodePeer_Mode
then
1132 Make_If_Statement
(Loc
,
1135 Left_Opnd
=> New_Occurrence_Of
(Lnn
(J
), Loc
),
1137 Make_Attribute_Reference
(Loc
,
1138 Prefix
=> New_Occurrence_Of
(L_Index_Type
(J
), Loc
),
1139 Attribute_Name
=> Lim
)),
1140 Then_Statements
=> New_List
(Step
));
1146 -- Start of processing for Expand_Assign_Array_Loop
1150 F_Or_L
:= Name_Last
;
1151 S_Or_P
:= Name_Pred
;
1153 F_Or_L
:= Name_First
;
1154 S_Or_P
:= Name_Succ
;
1157 -- Setup index types and subscript entities
1164 L_Index
:= First_Index
(L_Type
);
1165 R_Index
:= First_Index
(R_Type
);
1167 for J
in 1 .. Ndim
loop
1168 Lnn
(J
) := Make_Temporary
(Loc
, 'L');
1169 Rnn
(J
) := Make_Temporary
(Loc
, 'R');
1171 L_Index_Type
(J
) := Etype
(L_Index
);
1172 R_Index_Type
(J
) := Etype
(R_Index
);
1174 Next_Index
(L_Index
);
1175 Next_Index
(R_Index
);
1179 -- Now construct the assignment statement
1182 ExprL
: constant List_Id
:= New_List
;
1183 ExprR
: constant List_Id
:= New_List
;
1186 for J
in 1 .. Ndim
loop
1187 Append_To
(ExprL
, New_Occurrence_Of
(Lnn
(J
), Loc
));
1188 Append_To
(ExprR
, New_Occurrence_Of
(Rnn
(J
), Loc
));
1192 Make_Assignment_Statement
(Loc
,
1194 Make_Indexed_Component
(Loc
,
1195 Prefix
=> Duplicate_Subexpr
(Larray
, Name_Req
=> True),
1196 Expressions
=> ExprL
),
1198 Make_Indexed_Component
(Loc
,
1199 Prefix
=> Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
1200 Expressions
=> ExprR
));
1202 -- We set assignment OK, since there are some cases, e.g. in object
1203 -- declarations, where we are actually assigning into a constant.
1204 -- If there really is an illegality, it was caught long before now,
1205 -- and was flagged when the original assignment was analyzed.
1207 Set_Assignment_OK
(Name
(Assign
));
1209 -- Propagate the No_Ctrl_Actions flag to individual assignments
1211 Set_No_Ctrl_Actions
(Assign
, No_Ctrl_Actions
(N
));
1214 -- Now construct the loop from the inside out, with the last subscript
1215 -- varying most rapidly. Note that Assign is first the raw assignment
1216 -- statement, and then subsequently the loop that wraps it up.
1218 for J
in reverse 1 .. Ndim
loop
1220 Make_Block_Statement
(Loc
,
1221 Declarations
=> New_List
(
1222 Make_Object_Declaration
(Loc
,
1223 Defining_Identifier
=> Rnn
(J
),
1224 Object_Definition
=>
1225 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1227 Make_Attribute_Reference
(Loc
,
1228 Prefix
=> New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1229 Attribute_Name
=> F_Or_L
))),
1231 Handled_Statement_Sequence
=>
1232 Make_Handled_Sequence_Of_Statements
(Loc
,
1233 Statements
=> New_List
(
1234 Make_Implicit_Loop_Statement
(N
,
1236 Make_Iteration_Scheme
(Loc
,
1237 Loop_Parameter_Specification
=>
1238 Make_Loop_Parameter_Specification
(Loc
,
1239 Defining_Identifier
=> Lnn
(J
),
1240 Reverse_Present
=> Rev
,
1241 Discrete_Subtype_Definition
=>
1242 New_Occurrence_Of
(L_Index_Type
(J
), Loc
))),
1244 Statements
=> New_List
(Assign
, Build_Step
(J
))))));
1248 end Expand_Assign_Array_Loop
;
1250 --------------------------
1251 -- Expand_Assign_Record --
1252 --------------------------
1254 procedure Expand_Assign_Record
(N
: Node_Id
) is
1255 Lhs
: constant Node_Id
:= Name
(N
);
1256 Rhs
: Node_Id
:= Expression
(N
);
1257 L_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Lhs
));
1260 -- If change of representation, then extract the real right hand side
1261 -- from the type conversion, and proceed with component-wise assignment,
1262 -- since the two types are not the same as far as the back end is
1265 if Change_Of_Representation
(N
) then
1266 Rhs
:= Expression
(Rhs
);
1268 -- If this may be a case of a large bit aligned component, then proceed
1269 -- with component-wise assignment, to avoid possible clobbering of other
1270 -- components sharing bits in the first or last byte of the component to
1273 elsif Possible_Bit_Aligned_Component
(Lhs
)
1275 Possible_Bit_Aligned_Component
(Rhs
)
1279 -- If we have a tagged type that has a complete record representation
1280 -- clause, we must do we must do component-wise assignments, since child
1281 -- types may have used gaps for their components, and we might be
1282 -- dealing with a view conversion.
1284 elsif Is_Fully_Repped_Tagged_Type
(L_Typ
) then
1287 -- If neither condition met, then nothing special to do, the back end
1288 -- can handle assignment of the entire component as a single entity.
1294 -- At this stage we know that we must do a component wise assignment
1297 Loc
: constant Source_Ptr
:= Sloc
(N
);
1298 R_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Rhs
));
1299 Decl
: constant Node_Id
:= Declaration_Node
(R_Typ
);
1303 function Find_Component
1305 Comp
: Entity_Id
) return Entity_Id
;
1306 -- Find the component with the given name in the underlying record
1307 -- declaration for Typ. We need to use the actual entity because the
1308 -- type may be private and resolution by identifier alone would fail.
1310 function Make_Component_List_Assign
1312 U_U
: Boolean := False) return List_Id
;
1313 -- Returns a sequence of statements to assign the components that
1314 -- are referenced in the given component list. The flag U_U is
1315 -- used to force the usage of the inferred value of the variant
1316 -- part expression as the switch for the generated case statement.
1318 function Make_Field_Assign
1320 U_U
: Boolean := False) return Node_Id
;
1321 -- Given C, the entity for a discriminant or component, build an
1322 -- assignment for the corresponding field values. The flag U_U
1323 -- signals the presence of an Unchecked_Union and forces the usage
1324 -- of the inferred discriminant value of C as the right hand side
1325 -- of the assignment.
1327 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
;
1328 -- Given CI, a component items list, construct series of statements
1329 -- for fieldwise assignment of the corresponding components.
1331 --------------------
1332 -- Find_Component --
1333 --------------------
1335 function Find_Component
1337 Comp
: Entity_Id
) return Entity_Id
1339 Utyp
: constant Entity_Id
:= Underlying_Type
(Typ
);
1343 C
:= First_Entity
(Utyp
);
1344 while Present
(C
) loop
1345 if Chars
(C
) = Chars
(Comp
) then
1352 raise Program_Error
;
1355 --------------------------------
1356 -- Make_Component_List_Assign --
1357 --------------------------------
1359 function Make_Component_List_Assign
1361 U_U
: Boolean := False) return List_Id
1363 CI
: constant List_Id
:= Component_Items
(CL
);
1364 VP
: constant Node_Id
:= Variant_Part
(CL
);
1374 Result
:= Make_Field_Assigns
(CI
);
1376 if Present
(VP
) then
1377 V
:= First_Non_Pragma
(Variants
(VP
));
1379 while Present
(V
) loop
1381 DC
:= First
(Discrete_Choices
(V
));
1382 while Present
(DC
) loop
1383 Append_To
(DCH
, New_Copy_Tree
(DC
));
1388 Make_Case_Statement_Alternative
(Loc
,
1389 Discrete_Choices
=> DCH
,
1391 Make_Component_List_Assign
(Component_List
(V
))));
1392 Next_Non_Pragma
(V
);
1395 -- If we have an Unchecked_Union, use the value of the inferred
1396 -- discriminant of the variant part expression as the switch
1397 -- for the case statement. The case statement may later be
1402 New_Copy
(Get_Discriminant_Value
(
1405 Discriminant_Constraint
(Etype
(Rhs
))));
1408 Make_Selected_Component
(Loc
,
1409 Prefix
=> Duplicate_Subexpr
(Rhs
),
1411 Make_Identifier
(Loc
, Chars
(Name
(VP
))));
1415 Make_Case_Statement
(Loc
,
1417 Alternatives
=> Alts
));
1421 end Make_Component_List_Assign
;
1423 -----------------------
1424 -- Make_Field_Assign --
1425 -----------------------
1427 function Make_Field_Assign
1429 U_U
: Boolean := False) return Node_Id
1435 -- In the case of an Unchecked_Union, use the discriminant
1436 -- constraint value as on the right hand side of the assignment.
1440 New_Copy
(Get_Discriminant_Value
(C
,
1442 Discriminant_Constraint
(Etype
(Rhs
))));
1445 Make_Selected_Component
(Loc
,
1446 Prefix
=> Duplicate_Subexpr
(Rhs
),
1447 Selector_Name
=> New_Occurrence_Of
(C
, Loc
));
1451 Make_Assignment_Statement
(Loc
,
1453 Make_Selected_Component
(Loc
,
1454 Prefix
=> Duplicate_Subexpr
(Lhs
),
1456 New_Occurrence_Of
(Find_Component
(L_Typ
, C
), Loc
)),
1457 Expression
=> Expr
);
1459 -- Set Assignment_OK, so discriminants can be assigned
1461 Set_Assignment_OK
(Name
(A
), True);
1463 if Componentwise_Assignment
(N
)
1464 and then Nkind
(Name
(A
)) = N_Selected_Component
1465 and then Chars
(Selector_Name
(Name
(A
))) = Name_uParent
1467 Set_Componentwise_Assignment
(A
);
1471 end Make_Field_Assign
;
1473 ------------------------
1474 -- Make_Field_Assigns --
1475 ------------------------
1477 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
is
1485 while Present
(Item
) loop
1487 -- Look for components, but exclude _tag field assignment if
1488 -- the special Componentwise_Assignment flag is set.
1490 if Nkind
(Item
) = N_Component_Declaration
1491 and then not (Is_Tag
(Defining_Identifier
(Item
))
1492 and then Componentwise_Assignment
(N
))
1495 (Result
, Make_Field_Assign
(Defining_Identifier
(Item
)));
1502 end Make_Field_Assigns
;
1504 -- Start of processing for Expand_Assign_Record
1507 -- Note that we use the base types for this processing. This results
1508 -- in some extra work in the constrained case, but the change of
1509 -- representation case is so unusual that it is not worth the effort.
1511 -- First copy the discriminants. This is done unconditionally. It
1512 -- is required in the unconstrained left side case, and also in the
1513 -- case where this assignment was constructed during the expansion
1514 -- of a type conversion (since initialization of discriminants is
1515 -- suppressed in this case). It is unnecessary but harmless in
1518 if Has_Discriminants
(L_Typ
) then
1519 F
:= First_Discriminant
(R_Typ
);
1520 while Present
(F
) loop
1522 -- If we are expanding the initialization of a derived record
1523 -- that constrains or renames discriminants of the parent, we
1524 -- must use the corresponding discriminant in the parent.
1531 and then Present
(Corresponding_Discriminant
(F
))
1533 CF
:= Corresponding_Discriminant
(F
);
1538 if Is_Unchecked_Union
(Base_Type
(R_Typ
)) then
1540 -- Within an initialization procedure this is the
1541 -- assignment to an unchecked union component, in which
1542 -- case there is no discriminant to initialize.
1544 if Inside_Init_Proc
then
1548 -- The assignment is part of a conversion from a
1549 -- derived unchecked union type with an inferable
1550 -- discriminant, to a parent type.
1552 Insert_Action
(N
, Make_Field_Assign
(CF
, True));
1556 Insert_Action
(N
, Make_Field_Assign
(CF
));
1559 Next_Discriminant
(F
);
1564 -- We know the underlying type is a record, but its current view
1565 -- may be private. We must retrieve the usable record declaration.
1567 if Nkind_In
(Decl
, N_Private_Type_Declaration
,
1568 N_Private_Extension_Declaration
)
1569 and then Present
(Full_View
(R_Typ
))
1571 RDef
:= Type_Definition
(Declaration_Node
(Full_View
(R_Typ
)));
1573 RDef
:= Type_Definition
(Decl
);
1576 if Nkind
(RDef
) = N_Derived_Type_Definition
then
1577 RDef
:= Record_Extension_Part
(RDef
);
1580 if Nkind
(RDef
) = N_Record_Definition
1581 and then Present
(Component_List
(RDef
))
1583 if Is_Unchecked_Union
(R_Typ
) then
1585 Make_Component_List_Assign
(Component_List
(RDef
), True));
1588 (N
, Make_Component_List_Assign
(Component_List
(RDef
)));
1591 Rewrite
(N
, Make_Null_Statement
(Loc
));
1594 end Expand_Assign_Record
;
1596 -----------------------------------
1597 -- Expand_N_Assignment_Statement --
1598 -----------------------------------
1600 -- This procedure implements various cases where an assignment statement
1601 -- cannot just be passed on to the back end in untransformed state.
1603 procedure Expand_N_Assignment_Statement
(N
: Node_Id
) is
1604 Crep
: constant Boolean := Change_Of_Representation
(N
);
1605 Lhs
: constant Node_Id
:= Name
(N
);
1606 Loc
: constant Source_Ptr
:= Sloc
(N
);
1607 Rhs
: constant Node_Id
:= Expression
(N
);
1608 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Lhs
));
1611 Save_Ghost_Mode
: constant Ghost_Mode_Type
:= Ghost_Mode
;
1614 -- The assignment statement is Ghost when the left hand side is Ghost.
1615 -- Set the mode now to ensure that any nodes generated during expansion
1616 -- are properly marked as Ghost.
1620 -- Special case to check right away, if the Componentwise_Assignment
1621 -- flag is set, this is a reanalysis from the expansion of the primitive
1622 -- assignment procedure for a tagged type, and all we need to do is to
1623 -- expand to assignment of components, because otherwise, we would get
1624 -- infinite recursion (since this looks like a tagged assignment which
1625 -- would normally try to *call* the primitive assignment procedure).
1627 if Componentwise_Assignment
(N
) then
1628 Expand_Assign_Record
(N
);
1629 Ghost_Mode
:= Save_Ghost_Mode
;
1633 -- Defend against invalid subscripts on left side if we are in standard
1634 -- validity checking mode. No need to do this if we are checking all
1637 -- Note that we do this right away, because there are some early return
1638 -- paths in this procedure, and this is required on all paths.
1640 if Validity_Checks_On
1641 and then Validity_Check_Default
1642 and then not Validity_Check_Subscripts
1644 Check_Valid_Lvalue_Subscripts
(Lhs
);
1647 -- Ada 2005 (AI-327): Handle assignment to priority of protected object
1649 -- Rewrite an assignment to X'Priority into a run-time call
1651 -- For example: X'Priority := New_Prio_Expr;
1652 -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr);
1654 -- Note that although X'Priority is notionally an object, it is quite
1655 -- deliberately not defined as an aliased object in the RM. This means
1656 -- that it works fine to rewrite it as a call, without having to worry
1657 -- about complications that would other arise from X'Priority'Access,
1658 -- which is illegal, because of the lack of aliasing.
1660 if Ada_Version
>= Ada_2005
then
1663 Conctyp
: Entity_Id
;
1666 RT_Subprg_Name
: Node_Id
;
1669 -- Handle chains of renamings
1672 while Nkind
(Ent
) in N_Has_Entity
1673 and then Present
(Entity
(Ent
))
1674 and then Present
(Renamed_Object
(Entity
(Ent
)))
1676 Ent
:= Renamed_Object
(Entity
(Ent
));
1679 -- The attribute Priority applied to protected objects has been
1680 -- previously expanded into a call to the Get_Ceiling run-time
1681 -- subprogram. In restricted profiles this is not available.
1683 if Is_Expanded_Priority_Attribute
(Ent
) then
1685 -- Look for the enclosing concurrent type
1687 Conctyp
:= Current_Scope
;
1688 while not Is_Concurrent_Type
(Conctyp
) loop
1689 Conctyp
:= Scope
(Conctyp
);
1692 pragma Assert
(Is_Protected_Type
(Conctyp
));
1694 -- Generate the first actual of the call
1696 Subprg
:= Current_Scope
;
1697 while not Present
(Protected_Body_Subprogram
(Subprg
)) loop
1698 Subprg
:= Scope
(Subprg
);
1701 -- Select the appropriate run-time call
1703 if Number_Entries
(Conctyp
) = 0 then
1705 New_Occurrence_Of
(RTE
(RE_Set_Ceiling
), Loc
);
1708 New_Occurrence_Of
(RTE
(RO_PE_Set_Ceiling
), Loc
);
1712 Make_Procedure_Call_Statement
(Loc
,
1713 Name
=> RT_Subprg_Name
,
1714 Parameter_Associations
=> New_List
(
1715 New_Copy_Tree
(First
(Parameter_Associations
(Ent
))),
1716 Relocate_Node
(Expression
(N
))));
1721 Ghost_Mode
:= Save_Ghost_Mode
;
1727 -- Deal with assignment checks unless suppressed
1729 if not Suppress_Assignment_Checks
(N
) then
1731 -- First deal with generation of range check if required
1733 if Do_Range_Check
(Rhs
) then
1734 Generate_Range_Check
(Rhs
, Typ
, CE_Range_Check_Failed
);
1737 -- Then generate predicate check if required
1739 Apply_Predicate_Check
(Rhs
, Typ
);
1742 -- Check for a special case where a high level transformation is
1743 -- required. If we have either of:
1748 -- where P is a reference to a bit packed array, then we have to unwind
1749 -- the assignment. The exact meaning of being a reference to a bit
1750 -- packed array is as follows:
1752 -- An indexed component whose prefix is a bit packed array is a
1753 -- reference to a bit packed array.
1755 -- An indexed component or selected component whose prefix is a
1756 -- reference to a bit packed array is itself a reference ot a
1757 -- bit packed array.
1759 -- The required transformation is
1761 -- Tnn : prefix_type := P;
1762 -- Tnn.field := rhs;
1767 -- Tnn : prefix_type := P;
1768 -- Tnn (subscr) := rhs;
1771 -- Since P is going to be evaluated more than once, any subscripts
1772 -- in P must have their evaluation forced.
1774 if Nkind_In
(Lhs
, N_Indexed_Component
, N_Selected_Component
)
1775 and then Is_Ref_To_Bit_Packed_Array
(Prefix
(Lhs
))
1778 BPAR_Expr
: constant Node_Id
:= Relocate_Node
(Prefix
(Lhs
));
1779 BPAR_Typ
: constant Entity_Id
:= Etype
(BPAR_Expr
);
1780 Tnn
: constant Entity_Id
:=
1781 Make_Temporary
(Loc
, 'T', BPAR_Expr
);
1784 -- Insert the post assignment first, because we want to copy the
1785 -- BPAR_Expr tree before it gets analyzed in the context of the
1786 -- pre assignment. Note that we do not analyze the post assignment
1787 -- yet (we cannot till we have completed the analysis of the pre
1788 -- assignment). As usual, the analysis of this post assignment
1789 -- will happen on its own when we "run into" it after finishing
1790 -- the current assignment.
1793 Make_Assignment_Statement
(Loc
,
1794 Name
=> New_Copy_Tree
(BPAR_Expr
),
1795 Expression
=> New_Occurrence_Of
(Tnn
, Loc
)));
1797 -- At this stage BPAR_Expr is a reference to a bit packed array
1798 -- where the reference was not expanded in the original tree,
1799 -- since it was on the left side of an assignment. But in the
1800 -- pre-assignment statement (the object definition), BPAR_Expr
1801 -- will end up on the right hand side, and must be reexpanded. To
1802 -- achieve this, we reset the analyzed flag of all selected and
1803 -- indexed components down to the actual indexed component for
1804 -- the packed array.
1808 Set_Analyzed
(Exp
, False);
1811 (Exp
, N_Selected_Component
, N_Indexed_Component
)
1813 Exp
:= Prefix
(Exp
);
1819 -- Now we can insert and analyze the pre-assignment
1821 -- If the right-hand side requires a transient scope, it has
1822 -- already been placed on the stack. However, the declaration is
1823 -- inserted in the tree outside of this scope, and must reflect
1824 -- the proper scope for its variable. This awkward bit is forced
1825 -- by the stricter scope discipline imposed by GCC 2.97.
1828 Uses_Transient_Scope
: constant Boolean :=
1830 and then N
= Node_To_Be_Wrapped
;
1833 if Uses_Transient_Scope
then
1834 Push_Scope
(Scope
(Current_Scope
));
1837 Insert_Before_And_Analyze
(N
,
1838 Make_Object_Declaration
(Loc
,
1839 Defining_Identifier
=> Tnn
,
1840 Object_Definition
=> New_Occurrence_Of
(BPAR_Typ
, Loc
),
1841 Expression
=> BPAR_Expr
));
1843 if Uses_Transient_Scope
then
1848 -- Now fix up the original assignment and continue processing
1850 Rewrite
(Prefix
(Lhs
),
1851 New_Occurrence_Of
(Tnn
, Loc
));
1853 -- We do not need to reanalyze that assignment, and we do not need
1854 -- to worry about references to the temporary, but we do need to
1855 -- make sure that the temporary is not marked as a true constant
1856 -- since we now have a generated assignment to it.
1858 Set_Is_True_Constant
(Tnn
, False);
1862 -- When we have the appropriate type of aggregate in the expression (it
1863 -- has been determined during analysis of the aggregate by setting the
1864 -- delay flag), let's perform in place assignment and thus avoid
1865 -- creating a temporary.
1867 if Is_Delayed_Aggregate
(Rhs
) then
1868 Convert_Aggr_In_Assignment
(N
);
1869 Rewrite
(N
, Make_Null_Statement
(Loc
));
1872 Ghost_Mode
:= Save_Ghost_Mode
;
1876 -- Apply discriminant check if required. If Lhs is an access type to a
1877 -- designated type with discriminants, we must always check. If the
1878 -- type has unknown discriminants, more elaborate processing below.
1880 if Has_Discriminants
(Etype
(Lhs
))
1881 and then not Has_Unknown_Discriminants
(Etype
(Lhs
))
1883 -- Skip discriminant check if change of representation. Will be
1884 -- done when the change of representation is expanded out.
1887 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
), Lhs
);
1890 -- If the type is private without discriminants, and the full type
1891 -- has discriminants (necessarily with defaults) a check may still be
1892 -- necessary if the Lhs is aliased. The private discriminants must be
1893 -- visible to build the discriminant constraints.
1895 -- Only an explicit dereference that comes from source indicates
1896 -- aliasing. Access to formals of protected operations and entries
1897 -- create dereferences but are not semantic aliasings.
1899 elsif Is_Private_Type
(Etype
(Lhs
))
1900 and then Has_Discriminants
(Typ
)
1901 and then Nkind
(Lhs
) = N_Explicit_Dereference
1902 and then Comes_From_Source
(Lhs
)
1905 Lt
: constant Entity_Id
:= Etype
(Lhs
);
1906 Ubt
: Entity_Id
:= Base_Type
(Typ
);
1909 -- In the case of an expander-generated record subtype whose base
1910 -- type still appears private, Typ will have been set to that
1911 -- private type rather than the underlying record type (because
1912 -- Underlying type will have returned the record subtype), so it's
1913 -- necessary to apply Underlying_Type again to the base type to
1914 -- get the record type we need for the discriminant check. Such
1915 -- subtypes can be created for assignments in certain cases, such
1916 -- as within an instantiation passed this kind of private type.
1917 -- It would be good to avoid this special test, but making changes
1918 -- to prevent this odd form of record subtype seems difficult. ???
1920 if Is_Private_Type
(Ubt
) then
1921 Ubt
:= Underlying_Type
(Ubt
);
1924 Set_Etype
(Lhs
, Ubt
);
1925 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Ubt
), Rhs
));
1926 Apply_Discriminant_Check
(Rhs
, Ubt
, Lhs
);
1927 Set_Etype
(Lhs
, Lt
);
1930 -- If the Lhs has a private type with unknown discriminants, it may
1931 -- have a full view with discriminants, but those are nameable only
1932 -- in the underlying type, so convert the Rhs to it before potential
1933 -- checking. Convert Lhs as well, otherwise the actual subtype might
1934 -- not be constructible. If the discriminants have defaults the type
1935 -- is unconstrained and there is nothing to check.
1937 elsif Has_Unknown_Discriminants
(Base_Type
(Etype
(Lhs
)))
1938 and then Has_Discriminants
(Typ
)
1939 and then not Has_Defaulted_Discriminants
(Typ
)
1941 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
1942 Rewrite
(Lhs
, OK_Convert_To
(Base_Type
(Typ
), Lhs
));
1943 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
1945 -- In the access type case, we need the same discriminant check, and
1946 -- also range checks if we have an access to constrained array.
1948 elsif Is_Access_Type
(Etype
(Lhs
))
1949 and then Is_Constrained
(Designated_Type
(Etype
(Lhs
)))
1951 if Has_Discriminants
(Designated_Type
(Etype
(Lhs
))) then
1953 -- Skip discriminant check if change of representation. Will be
1954 -- done when the change of representation is expanded out.
1957 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
));
1960 elsif Is_Array_Type
(Designated_Type
(Etype
(Lhs
))) then
1961 Apply_Range_Check
(Rhs
, Etype
(Lhs
));
1963 if Is_Constrained
(Etype
(Lhs
)) then
1964 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
1967 if Nkind
(Rhs
) = N_Allocator
then
1969 Target_Typ
: constant Entity_Id
:= Etype
(Expression
(Rhs
));
1970 C_Es
: Check_Result
;
1977 Etype
(Designated_Type
(Etype
(Lhs
))));
1989 -- Apply range check for access type case
1991 elsif Is_Access_Type
(Etype
(Lhs
))
1992 and then Nkind
(Rhs
) = N_Allocator
1993 and then Nkind
(Expression
(Rhs
)) = N_Qualified_Expression
1995 Analyze_And_Resolve
(Expression
(Rhs
));
1997 (Expression
(Rhs
), Designated_Type
(Etype
(Lhs
)));
2000 -- Ada 2005 (AI-231): Generate the run-time check
2002 if Is_Access_Type
(Typ
)
2003 and then Can_Never_Be_Null
(Etype
(Lhs
))
2004 and then not Can_Never_Be_Null
(Etype
(Rhs
))
2006 -- If an actual is an out parameter of a null-excluding access
2007 -- type, there is access check on entry, so we set the flag
2008 -- Suppress_Assignment_Checks on the generated statement to
2009 -- assign the actual to the parameter block, and we do not want
2010 -- to generate an additional check at this point.
2012 and then not Suppress_Assignment_Checks
(N
)
2014 Apply_Constraint_Check
(Rhs
, Etype
(Lhs
));
2017 -- Ada 2012 (AI05-148): Update current accessibility level if Rhs is a
2018 -- stand-alone obj of an anonymous access type. Do not install the check
2019 -- when the Lhs denotes a container cursor and the Next function employs
2020 -- an access type, because this can never result in a dangling pointer.
2022 if Is_Access_Type
(Typ
)
2023 and then Is_Entity_Name
(Lhs
)
2024 and then Ekind
(Entity
(Lhs
)) /= E_Loop_Parameter
2025 and then Present
(Effective_Extra_Accessibility
(Entity
(Lhs
)))
2028 function Lhs_Entity
return Entity_Id
;
2029 -- Look through renames to find the underlying entity.
2030 -- For assignment to a rename, we don't care about the
2031 -- Enclosing_Dynamic_Scope of the rename declaration.
2037 function Lhs_Entity
return Entity_Id
is
2038 Result
: Entity_Id
:= Entity
(Lhs
);
2041 while Present
(Renamed_Object
(Result
)) loop
2043 -- Renamed_Object must return an Entity_Name here
2044 -- because of preceding "Present (E_E_A (...))" test.
2046 Result
:= Entity
(Renamed_Object
(Result
));
2052 -- Local Declarations
2054 Access_Check
: constant Node_Id
:=
2055 Make_Raise_Program_Error
(Loc
,
2059 Dynamic_Accessibility_Level
(Rhs
),
2061 Make_Integer_Literal
(Loc
,
2064 (Enclosing_Dynamic_Scope
2066 Reason
=> PE_Accessibility_Check_Failed
);
2068 Access_Level_Update
: constant Node_Id
:=
2069 Make_Assignment_Statement
(Loc
,
2072 (Effective_Extra_Accessibility
2073 (Entity
(Lhs
)), Loc
),
2075 Dynamic_Accessibility_Level
(Rhs
));
2078 if not Accessibility_Checks_Suppressed
(Entity
(Lhs
)) then
2079 Insert_Action
(N
, Access_Check
);
2082 Insert_Action
(N
, Access_Level_Update
);
2086 -- Case of assignment to a bit packed array element. If there is a
2087 -- change of representation this must be expanded into components,
2088 -- otherwise this is a bit-field assignment.
2090 if Nkind
(Lhs
) = N_Indexed_Component
2091 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Lhs
)))
2093 -- Normal case, no change of representation
2096 Expand_Bit_Packed_Element_Set
(N
);
2097 Ghost_Mode
:= Save_Ghost_Mode
;
2100 -- Change of representation case
2103 -- Generate the following, to force component-by-component
2104 -- assignments in an efficient way. Otherwise each component
2105 -- will require a temporary and two bit-field manipulations.
2112 Tnn
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T');
2118 Make_Object_Declaration
(Loc
,
2119 Defining_Identifier
=> Tnn
,
2120 Object_Definition
=>
2121 New_Occurrence_Of
(Etype
(Lhs
), Loc
)),
2122 Make_Assignment_Statement
(Loc
,
2123 Name
=> New_Occurrence_Of
(Tnn
, Loc
),
2124 Expression
=> Relocate_Node
(Rhs
)),
2125 Make_Assignment_Statement
(Loc
,
2126 Name
=> Relocate_Node
(Lhs
),
2127 Expression
=> New_Occurrence_Of
(Tnn
, Loc
)));
2129 Insert_Actions
(N
, Stats
);
2130 Rewrite
(N
, Make_Null_Statement
(Loc
));
2135 -- Build-in-place function call case. Note that we're not yet doing
2136 -- build-in-place for user-written assignment statements (the assignment
2137 -- here came from an aggregate.)
2139 elsif Ada_Version
>= Ada_2005
2140 and then Is_Build_In_Place_Function_Call
(Rhs
)
2142 Make_Build_In_Place_Call_In_Assignment
(N
, Rhs
);
2144 elsif Is_Tagged_Type
(Typ
)
2145 or else (Needs_Finalization
(Typ
) and then not Is_Array_Type
(Typ
))
2147 Tagged_Case
: declare
2148 L
: List_Id
:= No_List
;
2149 Expand_Ctrl_Actions
: constant Boolean := not No_Ctrl_Actions
(N
);
2152 -- In the controlled case, we ensure that function calls are
2153 -- evaluated before finalizing the target. In all cases, it makes
2154 -- the expansion easier if the side-effects are removed first.
2156 Remove_Side_Effects
(Lhs
);
2157 Remove_Side_Effects
(Rhs
);
2159 -- Avoid recursion in the mechanism
2163 -- If dispatching assignment, we need to dispatch to _assign
2165 if Is_Class_Wide_Type
(Typ
)
2167 -- If the type is tagged, we may as well use the predefined
2168 -- primitive assignment. This avoids inlining a lot of code
2169 -- and in the class-wide case, the assignment is replaced
2170 -- by a dispatching call to _assign. It is suppressed in the
2171 -- case of assignments created by the expander that correspond
2172 -- to initializations, where we do want to copy the tag
2173 -- (Expand_Ctrl_Actions flag is set False in this case). It is
2174 -- also suppressed if restriction No_Dispatching_Calls is in
2175 -- force because in that case predefined primitives are not
2178 or else (Is_Tagged_Type
(Typ
)
2179 and then Chars
(Current_Scope
) /= Name_uAssign
2180 and then Expand_Ctrl_Actions
2182 not Restriction_Active
(No_Dispatching_Calls
))
2184 if Is_Limited_Type
(Typ
) then
2186 -- This can happen in an instance when the formal is an
2187 -- extension of a limited interface, and the actual is
2188 -- limited. This is an error according to AI05-0087, but
2189 -- is not caught at the point of instantiation in earlier
2192 -- This is wrong, error messages cannot be issued during
2193 -- expansion, since they would be missed in -gnatc mode ???
2195 Error_Msg_N
("assignment not available on limited type", N
);
2196 Ghost_Mode
:= Save_Ghost_Mode
;
2200 -- Fetch the primitive op _assign and proper type to call it.
2201 -- Because of possible conflicts between private and full view,
2202 -- fetch the proper type directly from the operation profile.
2205 Op
: constant Entity_Id
:=
2206 Find_Prim_Op
(Typ
, Name_uAssign
);
2207 F_Typ
: Entity_Id
:= Etype
(First_Formal
(Op
));
2210 -- If the assignment is dispatching, make sure to use the
2213 if Is_Class_Wide_Type
(Typ
) then
2214 F_Typ
:= Class_Wide_Type
(F_Typ
);
2219 -- In case of assignment to a class-wide tagged type, before
2220 -- the assignment we generate run-time check to ensure that
2221 -- the tags of source and target match.
2223 if not Tag_Checks_Suppressed
(Typ
)
2224 and then Is_Class_Wide_Type
(Typ
)
2225 and then Is_Tagged_Type
(Typ
)
2226 and then Is_Tagged_Type
(Underlying_Type
(Etype
(Rhs
)))
2233 if not Is_Interface
(Typ
) then
2235 Make_Selected_Component
(Loc
,
2236 Prefix
=> Duplicate_Subexpr
(Lhs
),
2238 Make_Identifier
(Loc
, Name_uTag
));
2240 Make_Selected_Component
(Loc
,
2241 Prefix
=> Duplicate_Subexpr
(Rhs
),
2243 Make_Identifier
(Loc
, Name_uTag
));
2245 -- Displace the pointer to the base of the objects
2246 -- applying 'Address, which is later expanded into
2247 -- a call to RE_Base_Address.
2250 Make_Explicit_Dereference
(Loc
,
2252 Unchecked_Convert_To
(RTE
(RE_Tag_Ptr
),
2253 Make_Attribute_Reference
(Loc
,
2254 Prefix
=> Duplicate_Subexpr
(Lhs
),
2255 Attribute_Name
=> Name_Address
)));
2257 Make_Explicit_Dereference
(Loc
,
2259 Unchecked_Convert_To
(RTE
(RE_Tag_Ptr
),
2260 Make_Attribute_Reference
(Loc
,
2261 Prefix
=> Duplicate_Subexpr
(Rhs
),
2262 Attribute_Name
=> Name_Address
)));
2266 Make_Raise_Constraint_Error
(Loc
,
2269 Left_Opnd
=> Lhs_Tag
,
2270 Right_Opnd
=> Rhs_Tag
),
2271 Reason
=> CE_Tag_Check_Failed
));
2276 Left_N
: Node_Id
:= Duplicate_Subexpr
(Lhs
);
2277 Right_N
: Node_Id
:= Duplicate_Subexpr
(Rhs
);
2280 -- In order to dispatch the call to _assign the type of
2281 -- the actuals must match. Add conversion (if required).
2283 if Etype
(Lhs
) /= F_Typ
then
2284 Left_N
:= Unchecked_Convert_To
(F_Typ
, Left_N
);
2287 if Etype
(Rhs
) /= F_Typ
then
2288 Right_N
:= Unchecked_Convert_To
(F_Typ
, Right_N
);
2292 Make_Procedure_Call_Statement
(Loc
,
2293 Name
=> New_Occurrence_Of
(Op
, Loc
),
2294 Parameter_Associations
=> New_List
(
2296 Node2
=> Right_N
)));
2301 L
:= Make_Tag_Ctrl_Assignment
(N
);
2303 -- We can't afford to have destructive Finalization Actions in
2304 -- the Self assignment case, so if the target and the source
2305 -- are not obviously different, code is generated to avoid the
2306 -- self assignment case:
2308 -- if lhs'address /= rhs'address then
2309 -- <code for controlled and/or tagged assignment>
2312 -- Skip this if Restriction (No_Finalization) is active
2314 if not Statically_Different
(Lhs
, Rhs
)
2315 and then Expand_Ctrl_Actions
2316 and then not Restriction_Active
(No_Finalization
)
2319 Make_Implicit_If_Statement
(N
,
2323 Make_Attribute_Reference
(Loc
,
2324 Prefix
=> Duplicate_Subexpr
(Lhs
),
2325 Attribute_Name
=> Name_Address
),
2328 Make_Attribute_Reference
(Loc
,
2329 Prefix
=> Duplicate_Subexpr
(Rhs
),
2330 Attribute_Name
=> Name_Address
)),
2332 Then_Statements
=> L
));
2335 -- We need to set up an exception handler for implementing
2336 -- 7.6.1(18). The remaining adjustments are tackled by the
2337 -- implementation of adjust for record_controllers (see
2340 -- This is skipped if we have no finalization
2342 if Expand_Ctrl_Actions
2343 and then not Restriction_Active
(No_Finalization
)
2346 Make_Block_Statement
(Loc
,
2347 Handled_Statement_Sequence
=>
2348 Make_Handled_Sequence_Of_Statements
(Loc
,
2350 Exception_Handlers
=> New_List
(
2351 Make_Handler_For_Ctrl_Operation
(Loc
)))));
2356 Make_Block_Statement
(Loc
,
2357 Handled_Statement_Sequence
=>
2358 Make_Handled_Sequence_Of_Statements
(Loc
, Statements
=> L
)));
2360 -- If no restrictions on aborts, protect the whole assignment
2361 -- for controlled objects as per 9.8(11).
2363 if Needs_Finalization
(Typ
)
2364 and then Expand_Ctrl_Actions
2365 and then Abort_Allowed
2368 Blk
: constant Entity_Id
:=
2370 (E_Block
, Current_Scope
, Sloc
(N
), 'B');
2371 AUD
: constant Entity_Id
:= RTE
(RE_Abort_Undefer_Direct
);
2374 Set_Scope
(Blk
, Current_Scope
);
2375 Set_Etype
(Blk
, Standard_Void_Type
);
2376 Set_Identifier
(N
, New_Occurrence_Of
(Blk
, Sloc
(N
)));
2378 Prepend_To
(L
, Build_Runtime_Call
(Loc
, RE_Abort_Defer
));
2379 Set_At_End_Proc
(Handled_Statement_Sequence
(N
),
2380 New_Occurrence_Of
(AUD
, Loc
));
2382 -- Present the Abort_Undefer_Direct function to the backend
2383 -- so that it can inline the call to the function.
2385 Add_Inlined_Body
(AUD
, N
);
2387 Expand_At_End_Handler
2388 (Handled_Statement_Sequence
(N
), Blk
);
2392 -- N has been rewritten to a block statement for which it is
2393 -- known by construction that no checks are necessary: analyze
2394 -- it with all checks suppressed.
2396 Analyze
(N
, Suppress
=> All_Checks
);
2397 Ghost_Mode
:= Save_Ghost_Mode
;
2403 elsif Is_Array_Type
(Typ
) then
2405 Actual_Rhs
: Node_Id
:= Rhs
;
2408 while Nkind_In
(Actual_Rhs
, N_Type_Conversion
,
2409 N_Qualified_Expression
)
2411 Actual_Rhs
:= Expression
(Actual_Rhs
);
2414 Expand_Assign_Array
(N
, Actual_Rhs
);
2415 Ghost_Mode
:= Save_Ghost_Mode
;
2421 elsif Is_Record_Type
(Typ
) then
2422 Expand_Assign_Record
(N
);
2423 Ghost_Mode
:= Save_Ghost_Mode
;
2426 -- Scalar types. This is where we perform the processing related to the
2427 -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid
2430 elsif Is_Scalar_Type
(Typ
) then
2432 -- Case where right side is known valid
2434 if Expr_Known_Valid
(Rhs
) then
2436 -- Here the right side is valid, so it is fine. The case to deal
2437 -- with is when the left side is a local variable reference whose
2438 -- value is not currently known to be valid. If this is the case,
2439 -- and the assignment appears in an unconditional context, then
2440 -- we can mark the left side as now being valid if one of these
2441 -- conditions holds:
2443 -- The expression of the right side has Do_Range_Check set so
2444 -- that we know a range check will be performed. Note that it
2445 -- can be the case that a range check is omitted because we
2446 -- make the assumption that we can assume validity for operands
2447 -- appearing in the right side in determining whether a range
2448 -- check is required
2450 -- The subtype of the right side matches the subtype of the
2451 -- left side. In this case, even though we have not checked
2452 -- the range of the right side, we know it is in range of its
2453 -- subtype if the expression is valid.
2455 if Is_Local_Variable_Reference
(Lhs
)
2456 and then not Is_Known_Valid
(Entity
(Lhs
))
2457 and then In_Unconditional_Context
(N
)
2459 if Do_Range_Check
(Rhs
)
2460 or else Etype
(Lhs
) = Etype
(Rhs
)
2462 Set_Is_Known_Valid
(Entity
(Lhs
), True);
2466 -- Case where right side may be invalid in the sense of the RM
2467 -- reference above. The RM does not require that we check for the
2468 -- validity on an assignment, but it does require that the assignment
2469 -- of an invalid value not cause erroneous behavior.
2471 -- The general approach in GNAT is to use the Is_Known_Valid flag
2472 -- to avoid the need for validity checking on assignments. However
2473 -- in some cases, we have to do validity checking in order to make
2474 -- sure that the setting of this flag is correct.
2477 -- Validate right side if we are validating copies
2479 if Validity_Checks_On
2480 and then Validity_Check_Copies
2482 -- Skip this if left hand side is an array or record component
2483 -- and elementary component validity checks are suppressed.
2485 if Nkind_In
(Lhs
, N_Selected_Component
, N_Indexed_Component
)
2486 and then not Validity_Check_Components
2493 -- We can propagate this to the left side where appropriate
2495 if Is_Local_Variable_Reference
(Lhs
)
2496 and then not Is_Known_Valid
(Entity
(Lhs
))
2497 and then In_Unconditional_Context
(N
)
2499 Set_Is_Known_Valid
(Entity
(Lhs
), True);
2502 -- Otherwise check to see what should be done
2504 -- If left side is a local variable, then we just set its flag to
2505 -- indicate that its value may no longer be valid, since we are
2506 -- copying a potentially invalid value.
2508 elsif Is_Local_Variable_Reference
(Lhs
) then
2509 Set_Is_Known_Valid
(Entity
(Lhs
), False);
2511 -- Check for case of a nonlocal variable on the left side which
2512 -- is currently known to be valid. In this case, we simply ensure
2513 -- that the right side is valid. We only play the game of copying
2514 -- validity status for local variables, since we are doing this
2515 -- statically, not by tracing the full flow graph.
2517 elsif Is_Entity_Name
(Lhs
)
2518 and then Is_Known_Valid
(Entity
(Lhs
))
2520 -- Note: If Validity_Checking mode is set to none, we ignore
2521 -- the Ensure_Valid call so don't worry about that case here.
2525 -- In all other cases, we can safely copy an invalid value without
2526 -- worrying about the status of the left side. Since it is not a
2527 -- variable reference it will not be considered
2528 -- as being known to be valid in any case.
2536 Ghost_Mode
:= Save_Ghost_Mode
;
2539 when RE_Not_Available
=>
2540 Ghost_Mode
:= Save_Ghost_Mode
;
2542 end Expand_N_Assignment_Statement
;
2544 ------------------------------
2545 -- Expand_N_Block_Statement --
2546 ------------------------------
2548 -- Encode entity names defined in block statement
2550 procedure Expand_N_Block_Statement
(N
: Node_Id
) is
2552 Qualify_Entity_Names
(N
);
2553 end Expand_N_Block_Statement
;
2555 -----------------------------
2556 -- Expand_N_Case_Statement --
2557 -----------------------------
2559 procedure Expand_N_Case_Statement
(N
: Node_Id
) is
2560 Loc
: constant Source_Ptr
:= Sloc
(N
);
2561 Expr
: constant Node_Id
:= Expression
(N
);
2569 -- Check for the situation where we know at compile time which branch
2572 -- If the value is static but its subtype is predicated and the value
2573 -- does not obey the predicate, the value is marked non-static, and
2574 -- there can be no corresponding static alternative. In that case we
2575 -- replace the case statement with an exception, regardless of whether
2576 -- assertions are enabled or not, unless predicates are ignored.
2578 if Compile_Time_Known_Value
(Expr
)
2579 and then Has_Predicates
(Etype
(Expr
))
2580 and then not Predicates_Ignored
(Etype
(Expr
))
2581 and then not Is_OK_Static_Expression
(Expr
)
2584 Make_Raise_Constraint_Error
(Loc
, Reason
=> CE_Invalid_Data
));
2588 elsif Compile_Time_Known_Value
(Expr
)
2589 and then (not Has_Predicates
(Etype
(Expr
))
2590 or else Is_Static_Expression
(Expr
))
2592 Alt
:= Find_Static_Alternative
(N
);
2594 -- Do not consider controlled objects found in a case statement which
2595 -- actually models a case expression because their early finalization
2596 -- will affect the result of the expression.
2598 if not From_Conditional_Expression
(N
) then
2599 Process_Statements_For_Controlled_Objects
(Alt
);
2602 -- Move statements from this alternative after the case statement.
2603 -- They are already analyzed, so will be skipped by the analyzer.
2605 Insert_List_After
(N
, Statements
(Alt
));
2607 -- That leaves the case statement as a shell. So now we can kill all
2608 -- other alternatives in the case statement.
2610 Kill_Dead_Code
(Expression
(N
));
2616 -- Loop through case alternatives, skipping pragmas, and skipping
2617 -- the one alternative that we select (and therefore retain).
2619 Dead_Alt
:= First
(Alternatives
(N
));
2620 while Present
(Dead_Alt
) loop
2622 and then Nkind
(Dead_Alt
) = N_Case_Statement_Alternative
2624 Kill_Dead_Code
(Statements
(Dead_Alt
), Warn_On_Deleted_Code
);
2631 Rewrite
(N
, Make_Null_Statement
(Loc
));
2635 -- Here if the choice is not determined at compile time
2638 Last_Alt
: constant Node_Id
:= Last
(Alternatives
(N
));
2640 Others_Present
: Boolean;
2641 Others_Node
: Node_Id
;
2643 Then_Stms
: List_Id
;
2644 Else_Stms
: List_Id
;
2647 if Nkind
(First
(Discrete_Choices
(Last_Alt
))) = N_Others_Choice
then
2648 Others_Present
:= True;
2649 Others_Node
:= Last_Alt
;
2651 Others_Present
:= False;
2654 -- First step is to worry about possible invalid argument. The RM
2655 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
2656 -- outside the base range), then Constraint_Error must be raised.
2658 -- Case of validity check required (validity checks are on, the
2659 -- expression is not known to be valid, and the case statement
2660 -- comes from source -- no need to validity check internally
2661 -- generated case statements).
2663 if Validity_Check_Default
2664 and then not Predicates_Ignored
(Etype
(Expr
))
2666 Ensure_Valid
(Expr
);
2669 -- If there is only a single alternative, just replace it with the
2670 -- sequence of statements since obviously that is what is going to
2671 -- be executed in all cases.
2673 Len
:= List_Length
(Alternatives
(N
));
2677 -- We still need to evaluate the expression if it has any side
2680 Remove_Side_Effects
(Expression
(N
));
2681 Alt
:= First
(Alternatives
(N
));
2683 -- Do not consider controlled objects found in a case statement
2684 -- which actually models a case expression because their early
2685 -- finalization will affect the result of the expression.
2687 if not From_Conditional_Expression
(N
) then
2688 Process_Statements_For_Controlled_Objects
(Alt
);
2691 Insert_List_After
(N
, Statements
(Alt
));
2693 -- That leaves the case statement as a shell. The alternative that
2694 -- will be executed is reset to a null list. So now we can kill
2695 -- the entire case statement.
2697 Kill_Dead_Code
(Expression
(N
));
2698 Rewrite
(N
, Make_Null_Statement
(Loc
));
2701 -- An optimization. If there are only two alternatives, and only
2702 -- a single choice, then rewrite the whole case statement as an
2703 -- if statement, since this can result in subsequent optimizations.
2704 -- This helps not only with case statements in the source of a
2705 -- simple form, but also with generated code (discriminant check
2706 -- functions in particular).
2708 -- Note: it is OK to do this before expanding out choices for any
2709 -- static predicates, since the if statement processing will handle
2710 -- the static predicate case fine.
2713 Chlist
:= Discrete_Choices
(First
(Alternatives
(N
)));
2715 if List_Length
(Chlist
) = 1 then
2716 Choice
:= First
(Chlist
);
2718 Then_Stms
:= Statements
(First
(Alternatives
(N
)));
2719 Else_Stms
:= Statements
(Last
(Alternatives
(N
)));
2721 -- For TRUE, generate "expression", not expression = true
2723 if Nkind
(Choice
) = N_Identifier
2724 and then Entity
(Choice
) = Standard_True
2726 Cond
:= Expression
(N
);
2728 -- For FALSE, generate "expression" and switch then/else
2730 elsif Nkind
(Choice
) = N_Identifier
2731 and then Entity
(Choice
) = Standard_False
2733 Cond
:= Expression
(N
);
2734 Else_Stms
:= Statements
(First
(Alternatives
(N
)));
2735 Then_Stms
:= Statements
(Last
(Alternatives
(N
)));
2737 -- For a range, generate "expression in range"
2739 elsif Nkind
(Choice
) = N_Range
2740 or else (Nkind
(Choice
) = N_Attribute_Reference
2741 and then Attribute_Name
(Choice
) = Name_Range
)
2742 or else (Is_Entity_Name
(Choice
)
2743 and then Is_Type
(Entity
(Choice
)))
2747 Left_Opnd
=> Expression
(N
),
2748 Right_Opnd
=> Relocate_Node
(Choice
));
2750 -- A subtype indication is not a legal operator in a membership
2751 -- test, so retrieve its range.
2753 elsif Nkind
(Choice
) = N_Subtype_Indication
then
2756 Left_Opnd
=> Expression
(N
),
2759 (Range_Expression
(Constraint
(Choice
))));
2761 -- For any other subexpression "expression = value"
2766 Left_Opnd
=> Expression
(N
),
2767 Right_Opnd
=> Relocate_Node
(Choice
));
2770 -- Now rewrite the case as an IF
2773 Make_If_Statement
(Loc
,
2775 Then_Statements
=> Then_Stms
,
2776 Else_Statements
=> Else_Stms
));
2782 -- If the last alternative is not an Others choice, replace it with
2783 -- an N_Others_Choice. Note that we do not bother to call Analyze on
2784 -- the modified case statement, since it's only effect would be to
2785 -- compute the contents of the Others_Discrete_Choices which is not
2786 -- needed by the back end anyway.
2788 -- The reason for this is that the back end always needs some default
2789 -- for a switch, so if we have not supplied one in the processing
2790 -- above for validity checking, then we need to supply one here.
2792 if not Others_Present
then
2793 Others_Node
:= Make_Others_Choice
(Sloc
(Last_Alt
));
2795 -- If Predicates_Ignored is true the value does not satisfy the
2796 -- predicate, and there is no Others choice, Constraint_Error
2797 -- must be raised (4.5.7 (21/3)).
2799 if Predicates_Ignored
(Etype
(Expr
)) then
2801 Except
: constant Node_Id
:=
2802 Make_Raise_Constraint_Error
(Loc
,
2803 Reason
=> CE_Invalid_Data
);
2804 New_Alt
: constant Node_Id
:=
2805 Make_Case_Statement_Alternative
(Loc
,
2806 Discrete_Choices
=> New_List
(
2807 Make_Others_Choice
(Loc
)),
2808 Statements
=> New_List
(Except
));
2811 Append
(New_Alt
, Alternatives
(N
));
2812 Analyze_And_Resolve
(Except
);
2816 Set_Others_Discrete_Choices
2817 (Others_Node
, Discrete_Choices
(Last_Alt
));
2818 Set_Discrete_Choices
(Last_Alt
, New_List
(Others_Node
));
2823 -- Deal with possible declarations of controlled objects, and also
2824 -- with rewriting choice sequences for static predicate references.
2826 Alt
:= First_Non_Pragma
(Alternatives
(N
));
2827 while Present
(Alt
) loop
2829 -- Do not consider controlled objects found in a case statement
2830 -- which actually models a case expression because their early
2831 -- finalization will affect the result of the expression.
2833 if not From_Conditional_Expression
(N
) then
2834 Process_Statements_For_Controlled_Objects
(Alt
);
2837 if Has_SP_Choice
(Alt
) then
2838 Expand_Static_Predicates_In_Choices
(Alt
);
2841 Next_Non_Pragma
(Alt
);
2844 end Expand_N_Case_Statement
;
2846 -----------------------------
2847 -- Expand_N_Exit_Statement --
2848 -----------------------------
2850 -- The only processing required is to deal with a possible C/Fortran
2851 -- boolean value used as the condition for the exit statement.
2853 procedure Expand_N_Exit_Statement
(N
: Node_Id
) is
2855 Adjust_Condition
(Condition
(N
));
2856 end Expand_N_Exit_Statement
;
2858 ----------------------------------
2859 -- Expand_Formal_Container_Loop --
2860 ----------------------------------
2862 procedure Expand_Formal_Container_Loop
(N
: Node_Id
) is
2863 Loc
: constant Source_Ptr
:= Sloc
(N
);
2864 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
2865 I_Spec
: constant Node_Id
:= Iterator_Specification
(Isc
);
2866 Cursor
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
2867 Container
: constant Node_Id
:= Entity
(Name
(I_Spec
));
2868 Stats
: constant List_Id
:= Statements
(N
);
2876 -- The expansion resembles the one for Ada containers, but the
2877 -- primitives mention the domain of iteration explicitly, and
2878 -- function First applied to the container yields a cursor directly.
2880 -- Cursor : Cursor_type := First (Container);
2881 -- while Has_Element (Cursor, Container) loop
2882 -- <original loop statements>
2883 -- Cursor := Next (Container, Cursor);
2886 Build_Formal_Container_Iteration
2887 (N
, Container
, Cursor
, Init
, Advance
, New_Loop
);
2889 Set_Ekind
(Cursor
, E_Variable
);
2890 Append_To
(Stats
, Advance
);
2892 -- Build block to capture declaration of cursor entity.
2895 Make_Block_Statement
(Loc
,
2896 Declarations
=> New_List
(Init
),
2897 Handled_Statement_Sequence
=>
2898 Make_Handled_Sequence_Of_Statements
(Loc
,
2899 Statements
=> New_List
(New_Loop
)));
2901 Rewrite
(N
, Blk_Nod
);
2903 end Expand_Formal_Container_Loop
;
2905 ------------------------------------------
2906 -- Expand_Formal_Container_Element_Loop --
2907 ------------------------------------------
2909 procedure Expand_Formal_Container_Element_Loop
(N
: Node_Id
) is
2910 Loc
: constant Source_Ptr
:= Sloc
(N
);
2911 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
2912 I_Spec
: constant Node_Id
:= Iterator_Specification
(Isc
);
2913 Element
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
2914 Container
: constant Node_Id
:= Entity
(Name
(I_Spec
));
2915 Container_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Container
));
2916 Stats
: constant List_Id
:= Statements
(N
);
2918 Cursor
: constant Entity_Id
:=
2919 Make_Defining_Identifier
(Loc
,
2920 Chars
=> New_External_Name
(Chars
(Element
), 'C'));
2921 Elmt_Decl
: Node_Id
;
2924 Element_Op
: constant Entity_Id
:=
2925 Get_Iterable_Type_Primitive
(Container_Typ
, Name_Element
);
2932 -- For an element iterator, the Element aspect must be present,
2933 -- (this is checked during analysis) and the expansion takes the form:
2935 -- Cursor : Cursor_type := First (Container);
2936 -- Elmt : Element_Type;
2937 -- while Has_Element (Cursor, Container) loop
2938 -- Elmt := Element (Container, Cursor);
2939 -- <original loop statements>
2940 -- Cursor := Next (Container, Cursor);
2943 -- However this expansion is not legal if the element is indefinite.
2944 -- In that case we create a block to hold a variable declaration
2945 -- initialized with a call to Element, and generate:
2947 -- Cursor : Cursor_type := First (Container);
2948 -- while Has_Element (Cursor, Container) loop
2950 -- Elmt : Element-Type := Element (Container, Cursor);
2952 -- <original loop statements>
2953 -- Cursor := Next (Container, Cursor);
2957 Build_Formal_Container_Iteration
2958 (N
, Container
, Cursor
, Init
, Advance
, New_Loop
);
2959 Append_To
(Stats
, Advance
);
2961 Set_Ekind
(Cursor
, E_Variable
);
2962 Insert_Action
(N
, Init
);
2964 -- Declaration for Element.
2967 Make_Object_Declaration
(Loc
,
2968 Defining_Identifier
=> Element
,
2969 Object_Definition
=> New_Occurrence_Of
(Etype
(Element_Op
), Loc
));
2971 if not Is_Constrained
(Etype
(Element_Op
)) then
2972 Set_Expression
(Elmt_Decl
,
2973 Make_Function_Call
(Loc
,
2974 Name
=> New_Occurrence_Of
(Element_Op
, Loc
),
2975 Parameter_Associations
=> New_List
(
2976 New_Occurrence_Of
(Container
, Loc
),
2977 New_Occurrence_Of
(Cursor
, Loc
))));
2979 Set_Statements
(New_Loop
,
2981 (Make_Block_Statement
(Loc
,
2982 Declarations
=> New_List
(Elmt_Decl
),
2983 Handled_Statement_Sequence
=>
2984 Make_Handled_Sequence_Of_Statements
(Loc
,
2985 Statements
=> Stats
))));
2989 Make_Assignment_Statement
(Loc
,
2990 Name
=> New_Occurrence_Of
(Element
, Loc
),
2992 Make_Function_Call
(Loc
,
2993 Name
=> New_Occurrence_Of
(Element_Op
, Loc
),
2994 Parameter_Associations
=> New_List
(
2995 New_Occurrence_Of
(Container
, Loc
),
2996 New_Occurrence_Of
(Cursor
, Loc
))));
2998 Prepend
(Elmt_Ref
, Stats
);
3000 -- The element is assignable in the expanded code
3002 Set_Assignment_OK
(Name
(Elmt_Ref
));
3004 -- The loop is rewritten as a block, to hold the element declaration
3007 Make_Block_Statement
(Loc
,
3008 Declarations
=> New_List
(Elmt_Decl
),
3009 Handled_Statement_Sequence
=>
3010 Make_Handled_Sequence_Of_Statements
(Loc
,
3011 Statements
=> New_List
(New_Loop
)));
3014 -- The element is only modified in expanded code, so it appears as
3015 -- unassigned to the warning machinery. We must suppress this spurious
3016 -- warning explicitly.
3018 Set_Warnings_Off
(Element
);
3020 Rewrite
(N
, New_Loop
);
3022 -- The loop parameter is declared by an object declaration, but within
3023 -- the loop we must prevent user assignments to it, so we analyze the
3024 -- declaration and reset the entity kind, before analyzing the rest of
3027 Analyze
(Elmt_Decl
);
3028 Set_Ekind
(Defining_Identifier
(Elmt_Decl
), E_Loop_Parameter
);
3031 end Expand_Formal_Container_Element_Loop
;
3033 -----------------------------
3034 -- Expand_N_Goto_Statement --
3035 -----------------------------
3037 -- Add poll before goto if polling active
3039 procedure Expand_N_Goto_Statement
(N
: Node_Id
) is
3041 Generate_Poll_Call
(N
);
3042 end Expand_N_Goto_Statement
;
3044 ---------------------------
3045 -- Expand_N_If_Statement --
3046 ---------------------------
3048 -- First we deal with the case of C and Fortran convention boolean values,
3049 -- with zero/non-zero semantics.
3051 -- Second, we deal with the obvious rewriting for the cases where the
3052 -- condition of the IF is known at compile time to be True or False.
3054 -- Third, we remove elsif parts which have non-empty Condition_Actions and
3055 -- rewrite as independent if statements. For example:
3066 -- <<condition actions of y>>
3072 -- This rewriting is needed if at least one elsif part has a non-empty
3073 -- Condition_Actions list. We also do the same processing if there is a
3074 -- constant condition in an elsif part (in conjunction with the first
3075 -- processing step mentioned above, for the recursive call made to deal
3076 -- with the created inner if, this deals with properly optimizing the
3077 -- cases of constant elsif conditions).
3079 procedure Expand_N_If_Statement
(N
: Node_Id
) is
3080 Loc
: constant Source_Ptr
:= Sloc
(N
);
3085 Warn_If_Deleted
: constant Boolean :=
3086 Warn_On_Deleted_Code
and then Comes_From_Source
(N
);
3087 -- Indicates whether we want warnings when we delete branches of the
3088 -- if statement based on constant condition analysis. We never want
3089 -- these warnings for expander generated code.
3092 -- Do not consider controlled objects found in an if statement which
3093 -- actually models an if expression because their early finalization
3094 -- will affect the result of the expression.
3096 if not From_Conditional_Expression
(N
) then
3097 Process_Statements_For_Controlled_Objects
(N
);
3100 Adjust_Condition
(Condition
(N
));
3102 -- The following loop deals with constant conditions for the IF. We
3103 -- need a loop because as we eliminate False conditions, we grab the
3104 -- first elsif condition and use it as the primary condition.
3106 while Compile_Time_Known_Value
(Condition
(N
)) loop
3108 -- If condition is True, we can simply rewrite the if statement now
3109 -- by replacing it by the series of then statements.
3111 if Is_True
(Expr_Value
(Condition
(N
))) then
3113 -- All the else parts can be killed
3115 Kill_Dead_Code
(Elsif_Parts
(N
), Warn_If_Deleted
);
3116 Kill_Dead_Code
(Else_Statements
(N
), Warn_If_Deleted
);
3118 Hed
:= Remove_Head
(Then_Statements
(N
));
3119 Insert_List_After
(N
, Then_Statements
(N
));
3123 -- If condition is False, then we can delete the condition and
3124 -- the Then statements
3127 -- We do not delete the condition if constant condition warnings
3128 -- are enabled, since otherwise we end up deleting the desired
3129 -- warning. Of course the backend will get rid of this True/False
3130 -- test anyway, so nothing is lost here.
3132 if not Constant_Condition_Warnings
then
3133 Kill_Dead_Code
(Condition
(N
));
3136 Kill_Dead_Code
(Then_Statements
(N
), Warn_If_Deleted
);
3138 -- If there are no elsif statements, then we simply replace the
3139 -- entire if statement by the sequence of else statements.
3141 if No
(Elsif_Parts
(N
)) then
3142 if No
(Else_Statements
(N
))
3143 or else Is_Empty_List
(Else_Statements
(N
))
3146 Make_Null_Statement
(Sloc
(N
)));
3148 Hed
:= Remove_Head
(Else_Statements
(N
));
3149 Insert_List_After
(N
, Else_Statements
(N
));
3155 -- If there are elsif statements, the first of them becomes the
3156 -- if/then section of the rebuilt if statement This is the case
3157 -- where we loop to reprocess this copied condition.
3160 Hed
:= Remove_Head
(Elsif_Parts
(N
));
3161 Insert_Actions
(N
, Condition_Actions
(Hed
));
3162 Set_Condition
(N
, Condition
(Hed
));
3163 Set_Then_Statements
(N
, Then_Statements
(Hed
));
3165 -- Hed might have been captured as the condition determining
3166 -- the current value for an entity. Now it is detached from
3167 -- the tree, so a Current_Value pointer in the condition might
3168 -- need to be updated.
3170 Set_Current_Value_Condition
(N
);
3172 if Is_Empty_List
(Elsif_Parts
(N
)) then
3173 Set_Elsif_Parts
(N
, No_List
);
3179 -- Loop through elsif parts, dealing with constant conditions and
3180 -- possible condition actions that are present.
3182 if Present
(Elsif_Parts
(N
)) then
3183 E
:= First
(Elsif_Parts
(N
));
3184 while Present
(E
) loop
3186 -- Do not consider controlled objects found in an if statement
3187 -- which actually models an if expression because their early
3188 -- finalization will affect the result of the expression.
3190 if not From_Conditional_Expression
(N
) then
3191 Process_Statements_For_Controlled_Objects
(E
);
3194 Adjust_Condition
(Condition
(E
));
3196 -- If there are condition actions, then rewrite the if statement
3197 -- as indicated above. We also do the same rewrite for a True or
3198 -- False condition. The further processing of this constant
3199 -- condition is then done by the recursive call to expand the
3200 -- newly created if statement
3202 if Present
(Condition_Actions
(E
))
3203 or else Compile_Time_Known_Value
(Condition
(E
))
3205 -- Note this is not an implicit if statement, since it is part
3206 -- of an explicit if statement in the source (or of an implicit
3207 -- if statement that has already been tested).
3210 Make_If_Statement
(Sloc
(E
),
3211 Condition
=> Condition
(E
),
3212 Then_Statements
=> Then_Statements
(E
),
3213 Elsif_Parts
=> No_List
,
3214 Else_Statements
=> Else_Statements
(N
));
3216 -- Elsif parts for new if come from remaining elsif's of parent
3218 while Present
(Next
(E
)) loop
3219 if No
(Elsif_Parts
(New_If
)) then
3220 Set_Elsif_Parts
(New_If
, New_List
);
3223 Append
(Remove_Next
(E
), Elsif_Parts
(New_If
));
3226 Set_Else_Statements
(N
, New_List
(New_If
));
3228 if Present
(Condition_Actions
(E
)) then
3229 Insert_List_Before
(New_If
, Condition_Actions
(E
));
3234 if Is_Empty_List
(Elsif_Parts
(N
)) then
3235 Set_Elsif_Parts
(N
, No_List
);
3241 -- No special processing for that elsif part, move to next
3249 -- Some more optimizations applicable if we still have an IF statement
3251 if Nkind
(N
) /= N_If_Statement
then
3255 -- Another optimization, special cases that can be simplified
3257 -- if expression then
3263 -- can be changed to:
3265 -- return expression;
3269 -- if expression then
3275 -- can be changed to:
3277 -- return not (expression);
3279 -- Only do these optimizations if we are at least at -O1 level and
3280 -- do not do them if control flow optimizations are suppressed.
3282 if Optimization_Level
> 0
3283 and then not Opt
.Suppress_Control_Flow_Optimizations
3285 if Nkind
(N
) = N_If_Statement
3286 and then No
(Elsif_Parts
(N
))
3287 and then Present
(Else_Statements
(N
))
3288 and then List_Length
(Then_Statements
(N
)) = 1
3289 and then List_Length
(Else_Statements
(N
)) = 1
3292 Then_Stm
: constant Node_Id
:= First
(Then_Statements
(N
));
3293 Else_Stm
: constant Node_Id
:= First
(Else_Statements
(N
));
3296 if Nkind
(Then_Stm
) = N_Simple_Return_Statement
3298 Nkind
(Else_Stm
) = N_Simple_Return_Statement
3301 Then_Expr
: constant Node_Id
:= Expression
(Then_Stm
);
3302 Else_Expr
: constant Node_Id
:= Expression
(Else_Stm
);
3305 if Nkind
(Then_Expr
) = N_Identifier
3307 Nkind
(Else_Expr
) = N_Identifier
3309 if Entity
(Then_Expr
) = Standard_True
3310 and then Entity
(Else_Expr
) = Standard_False
3313 Make_Simple_Return_Statement
(Loc
,
3314 Expression
=> Relocate_Node
(Condition
(N
))));
3318 elsif Entity
(Then_Expr
) = Standard_False
3319 and then Entity
(Else_Expr
) = Standard_True
3322 Make_Simple_Return_Statement
(Loc
,
3326 Relocate_Node
(Condition
(N
)))));
3336 end Expand_N_If_Statement
;
3338 --------------------------
3339 -- Expand_Iterator_Loop --
3340 --------------------------
3342 procedure Expand_Iterator_Loop
(N
: Node_Id
) is
3343 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
3344 I_Spec
: constant Node_Id
:= Iterator_Specification
(Isc
);
3346 Container
: constant Node_Id
:= Name
(I_Spec
);
3347 Container_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Container
));
3350 -- Processing for arrays
3352 if Is_Array_Type
(Container_Typ
) then
3353 pragma Assert
(Of_Present
(I_Spec
));
3354 Expand_Iterator_Loop_Over_Array
(N
);
3356 elsif Has_Aspect
(Container_Typ
, Aspect_Iterable
) then
3357 if Of_Present
(I_Spec
) then
3358 Expand_Formal_Container_Element_Loop
(N
);
3360 Expand_Formal_Container_Loop
(N
);
3363 -- Processing for containers
3366 Expand_Iterator_Loop_Over_Container
3367 (N
, Isc
, I_Spec
, Container
, Container_Typ
);
3369 end Expand_Iterator_Loop
;
3371 -------------------------------------
3372 -- Expand_Iterator_Loop_Over_Array --
3373 -------------------------------------
3375 procedure Expand_Iterator_Loop_Over_Array
(N
: Node_Id
) is
3376 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
3377 I_Spec
: constant Node_Id
:= Iterator_Specification
(Isc
);
3378 Array_Node
: constant Node_Id
:= Name
(I_Spec
);
3379 Array_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Array_Node
));
3380 Array_Dim
: constant Pos
:= Number_Dimensions
(Array_Typ
);
3381 Id
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
3382 Loc
: constant Source_Ptr
:= Sloc
(N
);
3383 Stats
: constant List_Id
:= Statements
(N
);
3384 Core_Loop
: Node_Id
;
3387 Iterator
: Entity_Id
;
3389 -- Start of processing for Expand_Iterator_Loop_Over_Array
3392 -- for Element of Array loop
3394 -- It requires an internally generated cursor to iterate over the array
3396 pragma Assert
(Of_Present
(I_Spec
));
3398 Iterator
:= Make_Temporary
(Loc
, 'C');
3401 -- Element : Component_Type renames Array (Iterator);
3402 -- Iterator is the index value, or a list of index values
3403 -- in the case of a multidimensional array.
3406 Make_Indexed_Component
(Loc
,
3407 Prefix
=> Relocate_Node
(Array_Node
),
3408 Expressions
=> New_List
(New_Occurrence_Of
(Iterator
, Loc
)));
3411 Make_Object_Renaming_Declaration
(Loc
,
3412 Defining_Identifier
=> Id
,
3414 New_Occurrence_Of
(Component_Type
(Array_Typ
), Loc
),
3417 -- Mark the loop variable as needing debug info, so that expansion
3418 -- of the renaming will result in Materialize_Entity getting set via
3419 -- Debug_Renaming_Declaration. (This setting is needed here because
3420 -- the setting in Freeze_Entity comes after the expansion, which is
3423 Set_Debug_Info_Needed
(Id
);
3427 -- for Iterator in [reverse] Array'Range (Array_Dim) loop
3428 -- Element : Component_Type renames Array (Iterator);
3429 -- <original loop statements>
3432 -- If this is an iteration over a multidimensional array, the
3433 -- innermost loop is over the last dimension in Ada, and over
3434 -- the first dimension in Fortran.
3436 if Convention
(Array_Typ
) = Convention_Fortran
then
3443 Make_Loop_Statement
(Loc
,
3445 Make_Iteration_Scheme
(Loc
,
3446 Loop_Parameter_Specification
=>
3447 Make_Loop_Parameter_Specification
(Loc
,
3448 Defining_Identifier
=> Iterator
,
3449 Discrete_Subtype_Definition
=>
3450 Make_Attribute_Reference
(Loc
,
3451 Prefix
=> Relocate_Node
(Array_Node
),
3452 Attribute_Name
=> Name_Range
,
3453 Expressions
=> New_List
(
3454 Make_Integer_Literal
(Loc
, Dim1
))),
3455 Reverse_Present
=> Reverse_Present
(I_Spec
))),
3456 Statements
=> Stats
,
3457 End_Label
=> Empty
);
3459 -- Processing for multidimensional array. The body of each loop is
3460 -- a loop over a previous dimension, going in decreasing order in Ada
3461 -- and in increasing order in Fortran.
3463 if Array_Dim
> 1 then
3464 for Dim
in 1 .. Array_Dim
- 1 loop
3465 if Convention
(Array_Typ
) = Convention_Fortran
then
3468 Dim1
:= Array_Dim
- Dim
;
3471 Iterator
:= Make_Temporary
(Loc
, 'C');
3473 -- Generate the dimension loops starting from the innermost one
3475 -- for Iterator in [reverse] Array'Range (Array_Dim - Dim) loop
3480 Make_Loop_Statement
(Loc
,
3482 Make_Iteration_Scheme
(Loc
,
3483 Loop_Parameter_Specification
=>
3484 Make_Loop_Parameter_Specification
(Loc
,
3485 Defining_Identifier
=> Iterator
,
3486 Discrete_Subtype_Definition
=>
3487 Make_Attribute_Reference
(Loc
,
3488 Prefix
=> Relocate_Node
(Array_Node
),
3489 Attribute_Name
=> Name_Range
,
3490 Expressions
=> New_List
(
3491 Make_Integer_Literal
(Loc
, Dim1
))),
3492 Reverse_Present
=> Reverse_Present
(I_Spec
))),
3493 Statements
=> New_List
(Core_Loop
),
3494 End_Label
=> Empty
);
3496 -- Update the previously created object renaming declaration with
3497 -- the new iterator, by adding the index of the next loop to the
3498 -- indexed component, in the order that corresponds to the
3501 if Convention
(Array_Typ
) = Convention_Fortran
then
3502 Append_To
(Expressions
(Ind_Comp
),
3503 New_Occurrence_Of
(Iterator
, Loc
));
3505 Prepend_To
(Expressions
(Ind_Comp
),
3506 New_Occurrence_Of
(Iterator
, Loc
));
3511 -- Inherit the loop identifier from the original loop. This ensures that
3512 -- the scope stack is consistent after the rewriting.
3514 if Present
(Identifier
(N
)) then
3515 Set_Identifier
(Core_Loop
, Relocate_Node
(Identifier
(N
)));
3518 Rewrite
(N
, Core_Loop
);
3520 end Expand_Iterator_Loop_Over_Array
;
3522 -----------------------------------------
3523 -- Expand_Iterator_Loop_Over_Container --
3524 -----------------------------------------
3526 -- For a 'for ... in' loop, such as:
3528 -- for Cursor in Iterator_Function (...) loop
3534 -- Iter : Iterator_Type := Iterator_Function (...);
3535 -- Cursor : Cursor_type := First (Iter); -- or Last for "reverse"
3536 -- while Has_Element (Cursor) loop
3539 -- Cursor := Iter.Next (Cursor); -- or Prev for "reverse"
3542 -- For a 'for ... of' loop, such as:
3544 -- for X of Container loop
3548 -- the RM implies the generation of:
3550 -- Iter : Iterator_Type := Container.Iterate; -- the Default_Iterator
3551 -- Cursor : Cursor_Type := First (Iter); -- or Last for "reverse"
3552 -- while Has_Element (Cursor) loop
3554 -- X : Element_Type renames Element (Cursor).Element.all;
3555 -- -- or Constant_Element
3559 -- Cursor := Iter.Next (Cursor); -- or Prev for "reverse"
3562 -- In the general case, we do what the RM says. However, the operations
3563 -- Element and Iter.Next are slow, which is bad inside a loop, because they
3564 -- involve dispatching via interfaces, secondary stack manipulation,
3565 -- Busy/Lock incr/decr, and adjust/finalization/at-end handling. So for the
3566 -- predefined containers, we use an equivalent but optimized expansion.
3568 -- In the optimized case, we make use of these:
3570 -- procedure Next (Position : in out Cursor); -- instead of Iter.Next
3572 -- function Pseudo_Reference
3573 -- (Container : aliased Vector'Class) return Reference_Control_Type;
3575 -- type Element_Access is access all Element_Type;
3577 -- function Get_Element_Access
3578 -- (Position : Cursor) return not null Element_Access;
3580 -- Next is declared in the visible part of the container packages.
3581 -- The other three are added in the private part. (We're not supposed to
3582 -- pollute the namespace for clients. The compiler has no trouble breaking
3583 -- privacy to call things in the private part of an instance.)
3587 -- for X of My_Vector loop
3588 -- X.Count := X.Count + 1;
3592 -- The compiler will generate:
3594 -- Iter : Reversible_Iterator'Class := Iterate (My_Vector);
3595 -- -- Reversible_Iterator is an interface. Iterate is the
3596 -- -- Default_Iterator aspect of Vector. This increments Lock,
3597 -- -- disallowing tampering with cursors. Unfortunately, it does not
3598 -- -- increment Busy. The result of Iterate is Limited_Controlled;
3599 -- -- finalization will decrement Lock. This is a build-in-place
3600 -- -- dispatching call to Iterate.
3602 -- Cur : Cursor := First (Iter); -- or Last
3603 -- -- Dispatching call via interface.
3605 -- Control : Reference_Control_Type := Pseudo_Reference (My_Vector);
3606 -- -- Pseudo_Reference increments Busy, to detect tampering with
3607 -- -- elements, as required by RM. Also redundantly increment
3608 -- -- Lock. Finalization of Control will decrement both Busy and
3609 -- -- Lock. Pseudo_Reference returns a record containing a pointer to
3610 -- -- My_Vector, used by Finalize.
3612 -- -- Control is not used below, except to finalize it -- it's purely
3613 -- -- an RAII thing. This is needed because we are eliminating the
3614 -- -- call to Reference within the loop.
3616 -- while Has_Element (Cur) loop
3618 -- X : My_Element renames Get_Element_Access (Cur).all;
3619 -- -- Get_Element_Access returns a pointer to the element
3620 -- -- designated by Cur. No dispatching here, and no horsing
3621 -- -- around with access discriminants. This is instead of the
3624 -- -- X : My_Element renames Reference (Cur).Element.all;
3626 -- -- which creates a controlled object.
3628 -- -- Any attempt to tamper with My_Vector here in the loop
3629 -- -- will correctly raise Program_Error, because of the
3632 -- X.Count := X.Count + 1;
3635 -- Next (Cur); -- or Prev
3636 -- -- This is instead of "Cur := Next (Iter, Cur);"
3638 -- -- No finalization here
3640 -- Finalize Iter and Control here, decrementing Lock twice and Busy
3643 -- This optimization makes "for ... of" loops over 30 times faster in cases
3646 procedure Expand_Iterator_Loop_Over_Container
3650 Container
: Node_Id
;
3651 Container_Typ
: Entity_Id
)
3653 Id
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
3654 Elem_Typ
: constant Entity_Id
:= Etype
(Id
);
3655 Id_Kind
: constant Entity_Kind
:= Ekind
(Id
);
3656 Loc
: constant Source_Ptr
:= Sloc
(N
);
3657 Stats
: constant List_Id
:= Statements
(N
);
3661 Iter_Type
: Entity_Id
;
3662 Iterator
: Entity_Id
;
3663 Name_Init
: Name_Id
;
3664 Name_Step
: Name_Id
;
3667 Fast_Element_Access_Op
: Entity_Id
:= Empty
;
3668 Fast_Step_Op
: Entity_Id
:= Empty
;
3669 -- Only for optimized version of "for ... of"
3671 Iter_Pack
: Entity_Id
;
3672 -- The package in which the iterator interface is instantiated. This is
3673 -- typically an instance within the container package.
3676 -- The package in which the container type is declared
3679 -- Determine the advancement and initialization steps for the cursor.
3680 -- Analysis of the expanded loop will verify that the container has a
3681 -- reverse iterator.
3683 if Reverse_Present
(I_Spec
) then
3684 Name_Init
:= Name_Last
;
3685 Name_Step
:= Name_Previous
;
3687 Name_Init
:= Name_First
;
3688 Name_Step
:= Name_Next
;
3691 -- The type of the iterator is the return type of the Iterate function
3692 -- used. For the "of" form this is the default iterator for the type,
3693 -- otherwise it is the type of the explicit function used in the
3694 -- iterator specification. The most common case will be an Iterate
3695 -- function in the container package.
3697 -- The Iterator type is declared in an instance within the container
3698 -- package itself, for example:
3700 -- package Vector_Iterator_Interfaces is new
3701 -- Ada.Iterator_Interfaces (Cursor, Has_Element);
3703 -- If the container type is a derived type, the cursor type is found in
3704 -- the package of the ultimate ancestor type.
3706 if Is_Derived_Type
(Container_Typ
) then
3707 Pack
:= Scope
(Root_Type
(Container_Typ
));
3709 Pack
:= Scope
(Container_Typ
);
3712 if Of_Present
(I_Spec
) then
3714 Container_Arg
: Node_Id
;
3716 function Get_Default_Iterator
3717 (T
: Entity_Id
) return Entity_Id
;
3718 -- If the container is a derived type, the aspect holds the parent
3719 -- operation. The required one is a primitive of the derived type
3720 -- and is either inherited or overridden. Also sets Container_Arg.
3722 --------------------------
3723 -- Get_Default_Iterator --
3724 --------------------------
3726 function Get_Default_Iterator
3727 (T
: Entity_Id
) return Entity_Id
3729 Iter
: constant Entity_Id
:=
3730 Entity
(Find_Value_Of_Aspect
(T
, Aspect_Default_Iterator
));
3735 Container_Arg
:= New_Copy_Tree
(Container
);
3737 -- A previous version of GNAT allowed indexing aspects to
3738 -- be redefined on derived container types, while the
3739 -- default iterator was inherited from the parent type.
3740 -- This non-standard extension is preserved temporarily for
3741 -- use by the modelling project under debug flag d.X.
3743 if Debug_Flag_Dot_XX
then
3744 if Base_Type
(Etype
(Container
)) /=
3745 Base_Type
(Etype
(First_Formal
(Iter
)))
3748 Make_Type_Conversion
(Loc
,
3751 (Etype
(First_Formal
(Iter
)), Loc
),
3752 Expression
=> Container_Arg
);
3757 elsif Is_Derived_Type
(T
) then
3759 -- The default iterator must be a primitive operation of the
3760 -- type, at the same dispatch slot position.
3762 Prim
:= First_Elmt
(Primitive_Operations
(T
));
3763 while Present
(Prim
) loop
3766 if Chars
(Op
) = Chars
(Iter
)
3767 and then DT_Position
(Op
) = DT_Position
(Iter
)
3775 -- Default iterator must exist
3777 pragma Assert
(False);
3779 -- Otherwise not a derived type
3784 end Get_Default_Iterator
;
3788 Default_Iter
: Entity_Id
;
3791 Reference_Control_Type
: Entity_Id
:= Empty
;
3792 Pseudo_Reference
: Entity_Id
:= Empty
;
3794 -- Start of processing for Handle_Of
3797 if Is_Class_Wide_Type
(Container_Typ
) then
3799 Get_Default_Iterator
(Etype
(Base_Type
(Container_Typ
)));
3801 Default_Iter
:= Get_Default_Iterator
(Etype
(Container
));
3804 Cursor
:= Make_Temporary
(Loc
, 'C');
3806 -- For a container element iterator, the iterator type is obtained
3807 -- from the corresponding aspect, whose return type is descended
3808 -- from the corresponding interface type in some instance of
3809 -- Ada.Iterator_Interfaces. The actuals of that instantiation
3810 -- are Cursor and Has_Element.
3812 Iter_Type
:= Etype
(Default_Iter
);
3814 -- The iterator type, which is a class-wide type, may itself be
3815 -- derived locally, so the desired instantiation is the scope of
3816 -- the root type of the iterator type.
3818 Iter_Pack
:= Scope
(Root_Type
(Etype
(Iter_Type
)));
3820 -- Find declarations needed for "for ... of" optimization
3822 Ent
:= First_Entity
(Pack
);
3823 while Present
(Ent
) loop
3824 if Chars
(Ent
) = Name_Get_Element_Access
then
3825 Fast_Element_Access_Op
:= Ent
;
3827 elsif Chars
(Ent
) = Name_Step
3828 and then Ekind
(Ent
) = E_Procedure
3830 Fast_Step_Op
:= Ent
;
3832 elsif Chars
(Ent
) = Name_Reference_Control_Type
then
3833 Reference_Control_Type
:= Ent
;
3835 elsif Chars
(Ent
) = Name_Pseudo_Reference
then
3836 Pseudo_Reference
:= Ent
;
3842 if Present
(Reference_Control_Type
)
3843 and then Present
(Pseudo_Reference
)
3846 Make_Object_Declaration
(Loc
,
3847 Defining_Identifier
=> Make_Temporary
(Loc
, 'D'),
3848 Object_Definition
=>
3849 New_Occurrence_Of
(Reference_Control_Type
, Loc
),
3851 Make_Function_Call
(Loc
,
3853 New_Occurrence_Of
(Pseudo_Reference
, Loc
),
3854 Parameter_Associations
=>
3855 New_List
(New_Copy_Tree
(Container_Arg
)))));
3858 -- Rewrite domain of iteration as a call to the default iterator
3859 -- for the container type. The formal may be an access parameter
3860 -- in which case we must build a reference to the container.
3865 if Is_Access_Type
(Etype
(First_Entity
(Default_Iter
))) then
3867 Make_Attribute_Reference
(Loc
,
3868 Prefix
=> Container_Arg
,
3869 Attribute_Name
=> Name_Unrestricted_Access
);
3871 Arg
:= Container_Arg
;
3874 Rewrite
(Name
(I_Spec
),
3875 Make_Function_Call
(Loc
,
3877 New_Occurrence_Of
(Default_Iter
, Loc
),
3878 Parameter_Associations
=> New_List
(Arg
)));
3881 Analyze_And_Resolve
(Name
(I_Spec
));
3883 -- Find cursor type in proper iterator package, which is an
3884 -- instantiation of Iterator_Interfaces.
3886 Ent
:= First_Entity
(Iter_Pack
);
3887 while Present
(Ent
) loop
3888 if Chars
(Ent
) = Name_Cursor
then
3889 Set_Etype
(Cursor
, Etype
(Ent
));
3896 if Present
(Fast_Element_Access_Op
) then
3898 Make_Object_Renaming_Declaration
(Loc
,
3899 Defining_Identifier
=> Id
,
3901 New_Occurrence_Of
(Elem_Typ
, Loc
),
3903 Make_Explicit_Dereference
(Loc
,
3905 Make_Function_Call
(Loc
,
3907 New_Occurrence_Of
(Fast_Element_Access_Op
, Loc
),
3908 Parameter_Associations
=>
3909 New_List
(New_Occurrence_Of
(Cursor
, Loc
)))));
3913 Make_Object_Renaming_Declaration
(Loc
,
3914 Defining_Identifier
=> Id
,
3916 New_Occurrence_Of
(Elem_Typ
, Loc
),
3918 Make_Indexed_Component
(Loc
,
3919 Prefix
=> Relocate_Node
(Container_Arg
),
3921 New_List
(New_Occurrence_Of
(Cursor
, Loc
))));
3924 -- The defining identifier in the iterator is user-visible and
3925 -- must be visible in the debugger.
3927 Set_Debug_Info_Needed
(Id
);
3929 -- If the container does not have a variable indexing aspect,
3930 -- the element is a constant in the loop. The container itself
3931 -- may be constant, in which case the element is a constant as
3932 -- well. The container has been rewritten as a call to Iterate,
3933 -- so examine original node.
3935 if No
(Find_Value_Of_Aspect
3936 (Container_Typ
, Aspect_Variable_Indexing
))
3937 or else not Is_Variable
(Original_Node
(Container
))
3939 Set_Ekind
(Id
, E_Constant
);
3942 Prepend_To
(Stats
, Decl
);
3945 -- X in Iterate (S) : type of iterator is type of explicitly given
3946 -- Iterate function, and the loop variable is the cursor. It will be
3947 -- assigned in the loop and must be a variable.
3950 Iter_Type
:= Etype
(Name
(I_Spec
));
3952 -- The iterator type, which is a class-wide type, may itself be
3953 -- derived locally, so the desired instantiation is the scope of
3954 -- the root type of the iterator type, as in the "of" case.
3956 Iter_Pack
:= Scope
(Root_Type
(Etype
(Iter_Type
)));
3960 Iterator
:= Make_Temporary
(Loc
, 'I');
3962 -- For both iterator forms, add a call to the step operation to advance
3963 -- the cursor. Generate:
3965 -- Cursor := Iterator.Next (Cursor);
3969 -- Cursor := Next (Cursor);
3971 if Present
(Fast_Element_Access_Op
) and then Present
(Fast_Step_Op
) then
3973 Curs_Name
: constant Node_Id
:= New_Occurrence_Of
(Cursor
, Loc
);
3974 Step_Call
: Node_Id
;
3978 Make_Procedure_Call_Statement
(Loc
,
3980 New_Occurrence_Of
(Fast_Step_Op
, Loc
),
3981 Parameter_Associations
=> New_List
(Curs_Name
));
3983 Append_To
(Stats
, Step_Call
);
3984 Set_Assignment_OK
(Curs_Name
);
3993 Make_Function_Call
(Loc
,
3995 Make_Selected_Component
(Loc
,
3996 Prefix
=> New_Occurrence_Of
(Iterator
, Loc
),
3997 Selector_Name
=> Make_Identifier
(Loc
, Name_Step
)),
3998 Parameter_Associations
=> New_List
(
3999 New_Occurrence_Of
(Cursor
, Loc
)));
4002 Make_Assignment_Statement
(Loc
,
4003 Name
=> New_Occurrence_Of
(Cursor
, Loc
),
4004 Expression
=> Rhs
));
4005 Set_Assignment_OK
(Name
(Last
(Stats
)));
4010 -- while Has_Element (Cursor) loop
4014 -- Has_Element is the second actual in the iterator package
4017 Make_Loop_Statement
(Loc
,
4019 Make_Iteration_Scheme
(Loc
,
4021 Make_Function_Call
(Loc
,
4024 (Next_Entity
(First_Entity
(Iter_Pack
)), Loc
),
4025 Parameter_Associations
=> New_List
(
4026 New_Occurrence_Of
(Cursor
, Loc
)))),
4028 Statements
=> Stats
,
4029 End_Label
=> Empty
);
4031 -- If present, preserve identifier of loop, which can be used in an exit
4032 -- statement in the body.
4034 if Present
(Identifier
(N
)) then
4035 Set_Identifier
(New_Loop
, Relocate_Node
(Identifier
(N
)));
4038 -- Create the declarations for Iterator and cursor and insert them
4039 -- before the source loop. Given that the domain of iteration is already
4040 -- an entity, the iterator is just a renaming of that entity. Possible
4044 Make_Object_Renaming_Declaration
(Loc
,
4045 Defining_Identifier
=> Iterator
,
4046 Subtype_Mark
=> New_Occurrence_Of
(Iter_Type
, Loc
),
4047 Name
=> Relocate_Node
(Name
(I_Spec
))));
4049 -- Create declaration for cursor
4052 Cursor_Decl
: constant Node_Id
:=
4053 Make_Object_Declaration
(Loc
,
4054 Defining_Identifier
=> Cursor
,
4055 Object_Definition
=>
4056 New_Occurrence_Of
(Etype
(Cursor
), Loc
),
4058 Make_Selected_Component
(Loc
,
4060 New_Occurrence_Of
(Iterator
, Loc
),
4062 Make_Identifier
(Loc
, Name_Init
)));
4065 -- The cursor is only modified in expanded code, so it appears
4066 -- as unassigned to the warning machinery. We must suppress this
4067 -- spurious warning explicitly. The cursor's kind is that of the
4068 -- original loop parameter (it is a constant if the domain of
4069 -- iteration is constant).
4071 Set_Warnings_Off
(Cursor
);
4072 Set_Assignment_OK
(Cursor_Decl
);
4074 Insert_Action
(N
, Cursor_Decl
);
4075 Set_Ekind
(Cursor
, Id_Kind
);
4078 -- If the range of iteration is given by a function call that returns
4079 -- a container, the finalization actions have been saved in the
4080 -- Condition_Actions of the iterator. Insert them now at the head of
4083 if Present
(Condition_Actions
(Isc
)) then
4084 Insert_List_Before
(N
, Condition_Actions
(Isc
));
4087 Rewrite
(N
, New_Loop
);
4089 end Expand_Iterator_Loop_Over_Container
;
4091 -----------------------------
4092 -- Expand_N_Loop_Statement --
4093 -----------------------------
4095 -- 1. Remove null loop entirely
4096 -- 2. Deal with while condition for C/Fortran boolean
4097 -- 3. Deal with loops with a non-standard enumeration type range
4098 -- 4. Deal with while loops where Condition_Actions is set
4099 -- 5. Deal with loops over predicated subtypes
4100 -- 6. Deal with loops with iterators over arrays and containers
4101 -- 7. Insert polling call if required
4103 procedure Expand_N_Loop_Statement
(N
: Node_Id
) is
4104 Loc
: constant Source_Ptr
:= Sloc
(N
);
4105 Scheme
: constant Node_Id
:= Iteration_Scheme
(N
);
4111 if Is_Null_Loop
(N
) then
4112 Rewrite
(N
, Make_Null_Statement
(Loc
));
4116 -- Deal with condition for C/Fortran Boolean
4118 if Present
(Scheme
) then
4119 Adjust_Condition
(Condition
(Scheme
));
4122 -- Generate polling call
4124 if Is_Non_Empty_List
(Statements
(N
)) then
4125 Generate_Poll_Call
(First
(Statements
(N
)));
4128 -- Nothing more to do for plain loop with no iteration scheme
4133 -- Case of for loop (Loop_Parameter_Specification present)
4135 -- Note: we do not have to worry about validity checking of the for loop
4136 -- range bounds here, since they were frozen with constant declarations
4137 -- and it is during that process that the validity checking is done.
4139 elsif Present
(Loop_Parameter_Specification
(Scheme
)) then
4141 LPS
: constant Node_Id
:=
4142 Loop_Parameter_Specification
(Scheme
);
4143 Loop_Id
: constant Entity_Id
:= Defining_Identifier
(LPS
);
4144 Ltype
: constant Entity_Id
:= Etype
(Loop_Id
);
4145 Btype
: constant Entity_Id
:= Base_Type
(Ltype
);
4151 -- Deal with loop over predicates
4153 if Is_Discrete_Type
(Ltype
)
4154 and then Present
(Predicate_Function
(Ltype
))
4156 Expand_Predicated_Loop
(N
);
4158 -- Handle the case where we have a for loop with the range type
4159 -- being an enumeration type with non-standard representation.
4160 -- In this case we expand:
4162 -- for x in [reverse] a .. b loop
4168 -- for xP in [reverse] integer
4169 -- range etype'Pos (a) .. etype'Pos (b)
4172 -- x : constant etype := Pos_To_Rep (xP);
4178 elsif Is_Enumeration_Type
(Btype
)
4179 and then Present
(Enum_Pos_To_Rep
(Btype
))
4182 Make_Defining_Identifier
(Loc
,
4183 Chars
=> New_External_Name
(Chars
(Loop_Id
), 'P'));
4185 -- If the type has a contiguous representation, successive
4186 -- values can be generated as offsets from the first literal.
4188 if Has_Contiguous_Rep
(Btype
) then
4190 Unchecked_Convert_To
(Btype
,
4193 Make_Integer_Literal
(Loc
,
4194 Enumeration_Rep
(First_Literal
(Btype
))),
4195 Right_Opnd
=> New_Occurrence_Of
(New_Id
, Loc
)));
4197 -- Use the constructed array Enum_Pos_To_Rep
4200 Make_Indexed_Component
(Loc
,
4202 New_Occurrence_Of
(Enum_Pos_To_Rep
(Btype
), Loc
),
4204 New_List
(New_Occurrence_Of
(New_Id
, Loc
)));
4207 -- Build declaration for loop identifier
4211 Make_Object_Declaration
(Loc
,
4212 Defining_Identifier
=> Loop_Id
,
4213 Constant_Present
=> True,
4214 Object_Definition
=> New_Occurrence_Of
(Ltype
, Loc
),
4215 Expression
=> Expr
));
4218 Make_Loop_Statement
(Loc
,
4219 Identifier
=> Identifier
(N
),
4222 Make_Iteration_Scheme
(Loc
,
4223 Loop_Parameter_Specification
=>
4224 Make_Loop_Parameter_Specification
(Loc
,
4225 Defining_Identifier
=> New_Id
,
4226 Reverse_Present
=> Reverse_Present
(LPS
),
4228 Discrete_Subtype_Definition
=>
4229 Make_Subtype_Indication
(Loc
,
4232 New_Occurrence_Of
(Standard_Natural
, Loc
),
4235 Make_Range_Constraint
(Loc
,
4240 Make_Attribute_Reference
(Loc
,
4242 New_Occurrence_Of
(Btype
, Loc
),
4244 Attribute_Name
=> Name_Pos
,
4246 Expressions
=> New_List
(
4248 (Type_Low_Bound
(Ltype
)))),
4251 Make_Attribute_Reference
(Loc
,
4253 New_Occurrence_Of
(Btype
, Loc
),
4255 Attribute_Name
=> Name_Pos
,
4257 Expressions
=> New_List
(
4262 Statements
=> New_List
(
4263 Make_Block_Statement
(Loc
,
4264 Declarations
=> Decls
,
4265 Handled_Statement_Sequence
=>
4266 Make_Handled_Sequence_Of_Statements
(Loc
,
4267 Statements
=> Statements
(N
)))),
4269 End_Label
=> End_Label
(N
)));
4271 -- The loop parameter's entity must be removed from the loop
4272 -- scope's entity list and rendered invisible, since it will
4273 -- now be located in the new block scope. Any other entities
4274 -- already associated with the loop scope, such as the loop
4275 -- parameter's subtype, will remain there.
4277 -- In an element loop, the loop will contain a declaration for
4278 -- a cursor variable; otherwise the loop id is the first entity
4279 -- in the scope constructed for the loop.
4281 if Comes_From_Source
(Loop_Id
) then
4282 pragma Assert
(First_Entity
(Scope
(Loop_Id
)) = Loop_Id
);
4286 Set_First_Entity
(Scope
(Loop_Id
), Next_Entity
(Loop_Id
));
4287 Remove_Homonym
(Loop_Id
);
4289 if Last_Entity
(Scope
(Loop_Id
)) = Loop_Id
then
4290 Set_Last_Entity
(Scope
(Loop_Id
), Empty
);
4295 -- Nothing to do with other cases of for loops
4302 -- Second case, if we have a while loop with Condition_Actions set, then
4303 -- we change it into a plain loop:
4312 -- <<condition actions>>
4317 elsif Present
(Scheme
)
4318 and then Present
(Condition_Actions
(Scheme
))
4319 and then Present
(Condition
(Scheme
))
4326 Make_Exit_Statement
(Sloc
(Condition
(Scheme
)),
4328 Make_Op_Not
(Sloc
(Condition
(Scheme
)),
4329 Right_Opnd
=> Condition
(Scheme
)));
4331 Prepend
(ES
, Statements
(N
));
4332 Insert_List_Before
(ES
, Condition_Actions
(Scheme
));
4334 -- This is not an implicit loop, since it is generated in response
4335 -- to the loop statement being processed. If this is itself
4336 -- implicit, the restriction has already been checked. If not,
4337 -- it is an explicit loop.
4340 Make_Loop_Statement
(Sloc
(N
),
4341 Identifier
=> Identifier
(N
),
4342 Statements
=> Statements
(N
),
4343 End_Label
=> End_Label
(N
)));
4348 -- Here to deal with iterator case
4350 elsif Present
(Scheme
)
4351 and then Present
(Iterator_Specification
(Scheme
))
4353 Expand_Iterator_Loop
(N
);
4355 -- An iterator loop may generate renaming declarations for elements
4356 -- that require debug information. This is the case in particular
4357 -- with element iterators, where debug information must be generated
4358 -- for the temporary that holds the element value. These temporaries
4359 -- are created within a transient block whose local declarations are
4360 -- transferred to the loop, which now has nontrivial local objects.
4362 if Nkind
(N
) = N_Loop_Statement
4363 and then Present
(Identifier
(N
))
4365 Qualify_Entity_Names
(N
);
4369 -- When the iteration scheme mentiones attribute 'Loop_Entry, the loop
4370 -- is transformed into a conditional block where the original loop is
4371 -- the sole statement. Inspect the statements of the nested loop for
4372 -- controlled objects.
4376 if Subject_To_Loop_Entry_Attributes
(Stmt
) then
4377 Stmt
:= Find_Loop_In_Conditional_Block
(Stmt
);
4380 Process_Statements_For_Controlled_Objects
(Stmt
);
4381 end Expand_N_Loop_Statement
;
4383 ----------------------------
4384 -- Expand_Predicated_Loop --
4385 ----------------------------
4387 -- Note: the expander can handle generation of loops over predicated
4388 -- subtypes for both the dynamic and static cases. Depending on what
4389 -- we decide is allowed in Ada 2012 mode and/or extensions allowed
4390 -- mode, the semantic analyzer may disallow one or both forms.
4392 procedure Expand_Predicated_Loop
(N
: Node_Id
) is
4393 Loc
: constant Source_Ptr
:= Sloc
(N
);
4394 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
4395 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Isc
);
4396 Loop_Id
: constant Entity_Id
:= Defining_Identifier
(LPS
);
4397 Ltype
: constant Entity_Id
:= Etype
(Loop_Id
);
4398 Stat
: constant List_Id
:= Static_Discrete_Predicate
(Ltype
);
4399 Stmts
: constant List_Id
:= Statements
(N
);
4402 -- Case of iteration over non-static predicate, should not be possible
4403 -- since this is not allowed by the semantics and should have been
4404 -- caught during analysis of the loop statement.
4407 raise Program_Error
;
4409 -- If the predicate list is empty, that corresponds to a predicate of
4410 -- False, in which case the loop won't run at all, and we rewrite the
4411 -- entire loop as a null statement.
4413 elsif Is_Empty_List
(Stat
) then
4414 Rewrite
(N
, Make_Null_Statement
(Loc
));
4417 -- For expansion over a static predicate we generate the following
4420 -- J : Ltype := min-val;
4425 -- when endpoint => J := startpoint;
4426 -- when endpoint => J := startpoint;
4428 -- when max-val => exit;
4429 -- when others => J := Lval'Succ (J);
4434 -- with min-val replaced by max-val and Succ replaced by Pred if the
4435 -- loop parameter specification carries a Reverse indicator.
4437 -- To make this a little clearer, let's take a specific example:
4439 -- type Int is range 1 .. 10;
4440 -- subtype StaticP is Int with
4441 -- predicate => StaticP in 3 | 10 | 5 .. 7;
4443 -- for L in StaticP loop
4444 -- Put_Line ("static:" & J'Img);
4447 -- In this case, the loop is transformed into
4454 -- when 3 => J := 5;
4455 -- when 7 => J := 10;
4457 -- when others => J := L'Succ (J);
4463 Static_Predicate
: declare
4470 function Lo_Val
(N
: Node_Id
) return Node_Id
;
4471 -- Given static expression or static range, returns an identifier
4472 -- whose value is the low bound of the expression value or range.
4474 function Hi_Val
(N
: Node_Id
) return Node_Id
;
4475 -- Given static expression or static range, returns an identifier
4476 -- whose value is the high bound of the expression value or range.
4482 function Hi_Val
(N
: Node_Id
) return Node_Id
is
4484 if Is_OK_Static_Expression
(N
) then
4485 return New_Copy
(N
);
4487 pragma Assert
(Nkind
(N
) = N_Range
);
4488 return New_Copy
(High_Bound
(N
));
4496 function Lo_Val
(N
: Node_Id
) return Node_Id
is
4498 if Is_OK_Static_Expression
(N
) then
4499 return New_Copy
(N
);
4501 pragma Assert
(Nkind
(N
) = N_Range
);
4502 return New_Copy
(Low_Bound
(N
));
4506 -- Start of processing for Static_Predicate
4509 -- Convert loop identifier to normal variable and reanalyze it so
4510 -- that this conversion works. We have to use the same defining
4511 -- identifier, since there may be references in the loop body.
4513 Set_Analyzed
(Loop_Id
, False);
4514 Set_Ekind
(Loop_Id
, E_Variable
);
4516 -- In most loops the loop variable is assigned in various
4517 -- alternatives in the body. However, in the rare case when
4518 -- the range specifies a single element, the loop variable
4519 -- may trigger a spurious warning that is could be constant.
4520 -- This warning might as well be suppressed.
4522 Set_Warnings_Off
(Loop_Id
);
4524 -- Loop to create branches of case statement
4528 if Reverse_Present
(LPS
) then
4530 -- Initial value is largest value in predicate.
4533 Make_Object_Declaration
(Loc
,
4534 Defining_Identifier
=> Loop_Id
,
4535 Object_Definition
=> New_Occurrence_Of
(Ltype
, Loc
),
4536 Expression
=> Hi_Val
(Last
(Stat
)));
4539 while Present
(P
) loop
4540 if No
(Prev
(P
)) then
4541 S
:= Make_Exit_Statement
(Loc
);
4544 Make_Assignment_Statement
(Loc
,
4545 Name
=> New_Occurrence_Of
(Loop_Id
, Loc
),
4546 Expression
=> Hi_Val
(Prev
(P
)));
4547 Set_Suppress_Assignment_Checks
(S
);
4551 Make_Case_Statement_Alternative
(Loc
,
4552 Statements
=> New_List
(S
),
4553 Discrete_Choices
=> New_List
(Lo_Val
(P
))));
4560 -- Initial value is smallest value in predicate.
4563 Make_Object_Declaration
(Loc
,
4564 Defining_Identifier
=> Loop_Id
,
4565 Object_Definition
=> New_Occurrence_Of
(Ltype
, Loc
),
4566 Expression
=> Lo_Val
(First
(Stat
)));
4569 while Present
(P
) loop
4570 if No
(Next
(P
)) then
4571 S
:= Make_Exit_Statement
(Loc
);
4574 Make_Assignment_Statement
(Loc
,
4575 Name
=> New_Occurrence_Of
(Loop_Id
, Loc
),
4576 Expression
=> Lo_Val
(Next
(P
)));
4577 Set_Suppress_Assignment_Checks
(S
);
4581 Make_Case_Statement_Alternative
(Loc
,
4582 Statements
=> New_List
(S
),
4583 Discrete_Choices
=> New_List
(Hi_Val
(P
))));
4589 -- Add others choice
4592 Name_Next
: Name_Id
;
4595 if Reverse_Present
(LPS
) then
4596 Name_Next
:= Name_Pred
;
4598 Name_Next
:= Name_Succ
;
4602 Make_Assignment_Statement
(Loc
,
4603 Name
=> New_Occurrence_Of
(Loop_Id
, Loc
),
4605 Make_Attribute_Reference
(Loc
,
4606 Prefix
=> New_Occurrence_Of
(Ltype
, Loc
),
4607 Attribute_Name
=> Name_Next
,
4608 Expressions
=> New_List
(
4609 New_Occurrence_Of
(Loop_Id
, Loc
))));
4610 Set_Suppress_Assignment_Checks
(S
);
4614 Make_Case_Statement_Alternative
(Loc
,
4615 Discrete_Choices
=> New_List
(Make_Others_Choice
(Loc
)),
4616 Statements
=> New_List
(S
)));
4618 -- Construct case statement and append to body statements
4621 Make_Case_Statement
(Loc
,
4622 Expression
=> New_Occurrence_Of
(Loop_Id
, Loc
),
4623 Alternatives
=> Alts
);
4624 Append_To
(Stmts
, Cstm
);
4628 Set_Suppress_Assignment_Checks
(D
);
4631 Make_Block_Statement
(Loc
,
4632 Declarations
=> New_List
(D
),
4633 Handled_Statement_Sequence
=>
4634 Make_Handled_Sequence_Of_Statements
(Loc
,
4635 Statements
=> New_List
(
4636 Make_Loop_Statement
(Loc
,
4637 Statements
=> Stmts
,
4638 End_Label
=> Empty
)))));
4641 end Static_Predicate
;
4643 end Expand_Predicated_Loop
;
4645 ------------------------------
4646 -- Make_Tag_Ctrl_Assignment --
4647 ------------------------------
4649 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
is
4650 Asn
: constant Node_Id
:= Relocate_Node
(N
);
4651 L
: constant Node_Id
:= Name
(N
);
4652 Loc
: constant Source_Ptr
:= Sloc
(N
);
4653 Res
: constant List_Id
:= New_List
;
4654 T
: constant Entity_Id
:= Underlying_Type
(Etype
(L
));
4656 Comp_Asn
: constant Boolean := Is_Fully_Repped_Tagged_Type
(T
);
4657 Ctrl_Act
: constant Boolean := Needs_Finalization
(T
)
4658 and then not No_Ctrl_Actions
(N
);
4659 Save_Tag
: constant Boolean := Is_Tagged_Type
(T
)
4660 and then not Comp_Asn
4661 and then not No_Ctrl_Actions
(N
)
4662 and then Tagged_Type_Expansion
;
4666 -- Finalize the target of the assignment when controlled
4668 -- We have two exceptions here:
4670 -- 1. If we are in an init proc since it is an initialization more
4671 -- than an assignment.
4673 -- 2. If the left-hand side is a temporary that was not initialized
4674 -- (or the parent part of a temporary since it is the case in
4675 -- extension aggregates). Such a temporary does not come from
4676 -- source. We must examine the original node for the prefix, because
4677 -- it may be a component of an entry formal, in which case it has
4678 -- been rewritten and does not appear to come from source either.
4680 -- Case of init proc
4682 if not Ctrl_Act
then
4685 -- The left hand side is an uninitialized temporary object
4687 elsif Nkind
(L
) = N_Type_Conversion
4688 and then Is_Entity_Name
(Expression
(L
))
4689 and then Nkind
(Parent
(Entity
(Expression
(L
)))) =
4690 N_Object_Declaration
4691 and then No_Initialization
(Parent
(Entity
(Expression
(L
))))
4698 (Obj_Ref
=> Duplicate_Subexpr_No_Checks
(L
),
4702 -- Save the Tag in a local variable Tag_Id
4705 Tag_Id
:= Make_Temporary
(Loc
, 'A');
4708 Make_Object_Declaration
(Loc
,
4709 Defining_Identifier
=> Tag_Id
,
4710 Object_Definition
=> New_Occurrence_Of
(RTE
(RE_Tag
), Loc
),
4712 Make_Selected_Component
(Loc
,
4713 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
4715 New_Occurrence_Of
(First_Tag_Component
(T
), Loc
))));
4717 -- Otherwise Tag_Id is not used
4723 -- If the tagged type has a full rep clause, expand the assignment into
4724 -- component-wise assignments. Mark the node as unanalyzed in order to
4725 -- generate the proper code and propagate this scenario by setting a
4726 -- flag to avoid infinite recursion.
4729 Set_Analyzed
(Asn
, False);
4730 Set_Componentwise_Assignment
(Asn
, True);
4733 Append_To
(Res
, Asn
);
4739 Make_Assignment_Statement
(Loc
,
4741 Make_Selected_Component
(Loc
,
4742 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
4744 New_Occurrence_Of
(First_Tag_Component
(T
), Loc
)),
4745 Expression
=> New_Occurrence_Of
(Tag_Id
, Loc
)));
4748 -- Adjust the target after the assignment when controlled (not in the
4749 -- init proc since it is an initialization more than an assignment).
4754 (Obj_Ref
=> Duplicate_Subexpr_Move_Checks
(L
),
4762 -- Could use comment here ???
4764 when RE_Not_Available
=>
4766 end Make_Tag_Ctrl_Assignment
;