1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2006, 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 2, 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 COPYING. If not, write --
19 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 with Atree
; use Atree
;
28 with Checks
; use Checks
;
29 with Einfo
; use Einfo
;
30 with Elists
; use Elists
;
31 with Exp_Aggr
; use Exp_Aggr
;
32 with Exp_Ch7
; use Exp_Ch7
;
33 with Exp_Ch11
; use Exp_Ch11
;
34 with Exp_Dbug
; use Exp_Dbug
;
35 with Exp_Pakd
; use Exp_Pakd
;
36 with Exp_Tss
; use Exp_Tss
;
37 with Exp_Util
; use Exp_Util
;
38 with Hostparm
; use Hostparm
;
39 with Nlists
; use Nlists
;
40 with Nmake
; use Nmake
;
42 with Restrict
; use Restrict
;
43 with Rident
; use Rident
;
44 with Rtsfind
; use Rtsfind
;
45 with Sinfo
; use Sinfo
;
47 with Sem_Ch3
; use Sem_Ch3
;
48 with Sem_Ch5
; use Sem_Ch5
;
49 with Sem_Ch8
; use Sem_Ch8
;
50 with Sem_Ch13
; use Sem_Ch13
;
51 with Sem_Eval
; use Sem_Eval
;
52 with Sem_Res
; use Sem_Res
;
53 with Sem_Util
; use Sem_Util
;
54 with Snames
; use Snames
;
55 with Stand
; use Stand
;
56 with Stringt
; use Stringt
;
57 with Tbuild
; use Tbuild
;
58 with Ttypes
; use Ttypes
;
59 with Uintp
; use Uintp
;
60 with Validsw
; use Validsw
;
62 package body Exp_Ch5
is
64 function Change_Of_Representation
(N
: Node_Id
) return Boolean;
65 -- Determine if the right hand side of the assignment N is a type
66 -- conversion which requires a change of representation. Called
67 -- only for the array and record cases.
69 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
);
70 -- N is an assignment which assigns an array value. This routine process
71 -- the various special cases and checks required for such assignments,
72 -- including change of representation. Rhs is normally simply the right
73 -- hand side of the assignment, except that if the right hand side is
74 -- a type conversion or a qualified expression, then the Rhs is the
75 -- actual expression inside any such type conversions or qualifications.
77 function Expand_Assign_Array_Loop
84 Rev
: Boolean) return Node_Id
;
85 -- N is an assignment statement which assigns an array value. This routine
86 -- expands the assignment into a loop (or nested loops for the case of a
87 -- multi-dimensional array) to do the assignment component by component.
88 -- Larray and Rarray are the entities of the actual arrays on the left
89 -- hand and right hand sides. L_Type and R_Type are the types of these
90 -- arrays (which may not be the same, due to either sliding, or to a
91 -- change of representation case). Ndim is the number of dimensions and
92 -- the parameter Rev indicates if the loops run normally (Rev = False),
93 -- or reversed (Rev = True). The value returned is the constructed
94 -- loop statement. Auxiliary declarations are inserted before node N
95 -- using the standard Insert_Actions mechanism.
97 procedure Expand_Assign_Record
(N
: Node_Id
);
98 -- N is an assignment of a non-tagged record value. This routine handles
99 -- the case where the assignment must be made component by component,
100 -- either because the target is not byte aligned, or there is a change
101 -- of representation.
103 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
;
104 -- Generate the necessary code for controlled and tagged assignment,
105 -- that is to say, finalization of the target before, adjustement of
106 -- the target after and save and restore of the tag and finalization
107 -- pointers which are not 'part of the value' and must not be changed
108 -- upon assignment. N is the original Assignment node.
110 function Possible_Bit_Aligned_Component
(N
: Node_Id
) return Boolean;
111 -- This function is used in processing the assignment of a record or
112 -- indexed component. The argument N is either the left hand or right
113 -- hand side of an assignment, and this function determines if there
114 -- is a record component reference where the record may be bit aligned
115 -- in a manner that causes trouble for the back end (see description
116 -- of Exp_Util.Component_May_Be_Bit_Aligned for further details).
118 ------------------------------
119 -- Change_Of_Representation --
120 ------------------------------
122 function Change_Of_Representation
(N
: Node_Id
) return Boolean is
123 Rhs
: constant Node_Id
:= Expression
(N
);
126 Nkind
(Rhs
) = N_Type_Conversion
128 not Same_Representation
(Etype
(Rhs
), Etype
(Expression
(Rhs
)));
129 end Change_Of_Representation
;
131 -------------------------
132 -- Expand_Assign_Array --
133 -------------------------
135 -- There are two issues here. First, do we let Gigi do a block move, or
136 -- do we expand out into a loop? Second, we need to set the two flags
137 -- Forwards_OK and Backwards_OK which show whether the block move (or
138 -- corresponding loops) can be legitimately done in a forwards (low to
139 -- high) or backwards (high to low) manner.
141 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
) is
142 Loc
: constant Source_Ptr
:= Sloc
(N
);
144 Lhs
: constant Node_Id
:= Name
(N
);
146 Act_Lhs
: constant Node_Id
:= Get_Referenced_Object
(Lhs
);
147 Act_Rhs
: Node_Id
:= Get_Referenced_Object
(Rhs
);
149 L_Type
: constant Entity_Id
:=
150 Underlying_Type
(Get_Actual_Subtype
(Act_Lhs
));
151 R_Type
: Entity_Id
:=
152 Underlying_Type
(Get_Actual_Subtype
(Act_Rhs
));
154 L_Slice
: constant Boolean := Nkind
(Act_Lhs
) = N_Slice
;
155 R_Slice
: constant Boolean := Nkind
(Act_Rhs
) = N_Slice
;
157 Crep
: constant Boolean := Change_Of_Representation
(N
);
162 Ndim
: constant Pos
:= Number_Dimensions
(L_Type
);
164 Loop_Required
: Boolean := False;
165 -- This switch is set to True if the array move must be done using
166 -- an explicit front end generated loop.
168 procedure Apply_Dereference
(Arg
: in out Node_Id
);
169 -- If the argument is an access to an array, and the assignment is
170 -- converted into a procedure call, apply explicit dereference.
172 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean;
173 -- Test if Exp is a reference to an array whose declaration has
174 -- an address clause, or it is a slice of such an array.
176 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean;
177 -- Test if Exp is a reference to an array which is either a formal
178 -- parameter or a slice of a formal parameter. These are the cases
179 -- where hidden aliasing can occur.
181 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean;
182 -- Determine if Exp is a reference to an array variable which is other
183 -- than an object defined in the current scope, or a slice of such
184 -- an object. Such objects can be aliased to parameters (unlike local
185 -- array references).
187 -----------------------
188 -- Apply_Dereference --
189 -----------------------
191 procedure Apply_Dereference
(Arg
: in out Node_Id
) is
192 Typ
: constant Entity_Id
:= Etype
(Arg
);
194 if Is_Access_Type
(Typ
) then
195 Rewrite
(Arg
, Make_Explicit_Dereference
(Loc
,
196 Prefix
=> Relocate_Node
(Arg
)));
197 Analyze_And_Resolve
(Arg
, Designated_Type
(Typ
));
199 end Apply_Dereference
;
201 ------------------------
202 -- Has_Address_Clause --
203 ------------------------
205 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean is
208 (Is_Entity_Name
(Exp
) and then
209 Present
(Address_Clause
(Entity
(Exp
))))
211 (Nkind
(Exp
) = N_Slice
and then Has_Address_Clause
(Prefix
(Exp
)));
212 end Has_Address_Clause
;
214 ---------------------
215 -- Is_Formal_Array --
216 ---------------------
218 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean is
221 (Is_Entity_Name
(Exp
) and then Is_Formal
(Entity
(Exp
)))
223 (Nkind
(Exp
) = N_Slice
and then Is_Formal_Array
(Prefix
(Exp
)));
226 ------------------------
227 -- Is_Non_Local_Array --
228 ------------------------
230 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean is
232 return (Is_Entity_Name
(Exp
)
233 and then Scope
(Entity
(Exp
)) /= Current_Scope
)
234 or else (Nkind
(Exp
) = N_Slice
235 and then Is_Non_Local_Array
(Prefix
(Exp
)));
236 end Is_Non_Local_Array
;
238 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
240 Lhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Lhs
);
241 Rhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Rhs
);
243 Lhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Lhs
);
244 Rhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Rhs
);
246 -- Start of processing for Expand_Assign_Array
249 -- Deal with length check, note that the length check is done with
250 -- respect to the right hand side as given, not a possible underlying
251 -- renamed object, since this would generate incorrect extra checks.
253 Apply_Length_Check
(Rhs
, L_Type
);
255 -- We start by assuming that the move can be done in either
256 -- direction, i.e. that the two sides are completely disjoint.
258 Set_Forwards_OK
(N
, True);
259 Set_Backwards_OK
(N
, True);
261 -- Normally it is only the slice case that can lead to overlap,
262 -- and explicit checks for slices are made below. But there is
263 -- one case where the slice can be implicit and invisible to us
264 -- and that is the case where we have a one dimensional array,
265 -- and either both operands are parameters, or one is a parameter
266 -- and the other is a global variable. In this case the parameter
267 -- could be a slice that overlaps with the other parameter.
269 -- Check for the case of slices requiring an explicit loop. Normally
270 -- it is only the explicit slice cases that bother us, but in the
271 -- case of one dimensional arrays, parameters can be slices that
272 -- are passed by reference, so we can have aliasing for assignments
273 -- from one parameter to another, or assignments between parameters
274 -- and nonlocal variables. However, if the array subtype is a
275 -- constrained first subtype in the parameter case, then we don't
276 -- have to worry about overlap, since slice assignments aren't
277 -- possible (other than for a slice denoting the whole array).
279 -- Note: overlap is never possible if there is a change of
280 -- representation, so we can exclude this case.
285 ((Lhs_Formal
and Rhs_Formal
)
287 (Lhs_Formal
and Rhs_Non_Local_Var
)
289 (Rhs_Formal
and Lhs_Non_Local_Var
))
291 (not Is_Constrained
(Etype
(Lhs
))
292 or else not Is_First_Subtype
(Etype
(Lhs
)))
294 -- In the case of compiling for the Java Virtual Machine,
295 -- slices are always passed by making a copy, so we don't
296 -- have to worry about overlap. We also want to prevent
297 -- generation of "<" comparisons for array addresses,
298 -- since that's a meaningless operation on the JVM.
302 Set_Forwards_OK
(N
, False);
303 Set_Backwards_OK
(N
, False);
305 -- Note: the bit-packed case is not worrisome here, since if
306 -- we have a slice passed as a parameter, it is always aligned
307 -- on a byte boundary, and if there are no explicit slices, the
308 -- assignment can be performed directly.
311 -- We certainly must use a loop for change of representation
312 -- and also we use the operand of the conversion on the right
313 -- hand side as the effective right hand side (the component
314 -- types must match in this situation).
317 Act_Rhs
:= Get_Referenced_Object
(Rhs
);
318 R_Type
:= Get_Actual_Subtype
(Act_Rhs
);
319 Loop_Required
:= True;
321 -- We require a loop if the left side is possibly bit unaligned
323 elsif Possible_Bit_Aligned_Component
(Lhs
)
325 Possible_Bit_Aligned_Component
(Rhs
)
327 Loop_Required
:= True;
329 -- Arrays with controlled components are expanded into a loop
330 -- to force calls to adjust at the component level.
332 elsif Has_Controlled_Component
(L_Type
) then
333 Loop_Required
:= True;
335 -- If object is atomic, we cannot tolerate a loop
337 elsif Is_Atomic_Object
(Act_Lhs
)
339 Is_Atomic_Object
(Act_Rhs
)
343 -- Loop is required if we have atomic components since we have to
344 -- be sure to do any accesses on an element by element basis.
346 elsif Has_Atomic_Components
(L_Type
)
347 or else Has_Atomic_Components
(R_Type
)
348 or else Is_Atomic
(Component_Type
(L_Type
))
349 or else Is_Atomic
(Component_Type
(R_Type
))
351 Loop_Required
:= True;
353 -- Case where no slice is involved
355 elsif not L_Slice
and not R_Slice
then
357 -- The following code deals with the case of unconstrained bit
358 -- packed arrays. The problem is that the template for such
359 -- arrays contains the bounds of the actual source level array,
361 -- But the copy of an entire array requires the bounds of the
362 -- underlying array. It would be nice if the back end could take
363 -- care of this, but right now it does not know how, so if we
364 -- have such a type, then we expand out into a loop, which is
365 -- inefficient but works correctly. If we don't do this, we
366 -- get the wrong length computed for the array to be moved.
367 -- The two cases we need to worry about are:
369 -- Explicit deference of an unconstrained packed array type as
370 -- in the following example:
373 -- type BITS is array(INTEGER range <>) of BOOLEAN;
374 -- pragma PACK(BITS);
375 -- type A is access BITS;
378 -- P1 := new BITS (1 .. 65_535);
379 -- P2 := new BITS (1 .. 65_535);
383 -- A formal parameter reference with an unconstrained bit
384 -- array type is the other case we need to worry about (here
385 -- we assume the same BITS type declared above:
387 -- procedure Write_All (File : out BITS; Contents : in BITS);
389 -- File.Storage := Contents;
392 -- We expand to a loop in either of these two cases
394 -- Question for future thought. Another potentially more efficient
395 -- approach would be to create the actual subtype, and then do an
396 -- unchecked conversion to this actual subtype ???
398 Check_Unconstrained_Bit_Packed_Array
: declare
400 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean;
401 -- Function to perform required test for the first case,
402 -- above (dereference of an unconstrained bit packed array)
404 -----------------------
405 -- Is_UBPA_Reference --
406 -----------------------
408 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean is
409 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Opnd
));
411 Des_Type
: Entity_Id
;
414 if Present
(Packed_Array_Type
(Typ
))
415 and then Is_Array_Type
(Packed_Array_Type
(Typ
))
416 and then not Is_Constrained
(Packed_Array_Type
(Typ
))
420 elsif Nkind
(Opnd
) = N_Explicit_Dereference
then
421 P_Type
:= Underlying_Type
(Etype
(Prefix
(Opnd
)));
423 if not Is_Access_Type
(P_Type
) then
427 Des_Type
:= Designated_Type
(P_Type
);
429 Is_Bit_Packed_Array
(Des_Type
)
430 and then not Is_Constrained
(Des_Type
);
436 end Is_UBPA_Reference
;
438 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
441 if Is_UBPA_Reference
(Lhs
)
443 Is_UBPA_Reference
(Rhs
)
445 Loop_Required
:= True;
447 -- Here if we do not have the case of a reference to a bit
448 -- packed unconstrained array case. In this case gigi can
449 -- most certainly handle the assignment if a forwards move
452 -- (could it handle the backwards case also???)
454 elsif Forwards_OK
(N
) then
457 end Check_Unconstrained_Bit_Packed_Array
;
459 -- The back end can always handle the assignment if the right side is a
460 -- string literal (note that overlap is definitely impossible in this
461 -- case). If the type is packed, a string literal is always converted
462 -- into aggregate, except in the case of a null slice, for which no
463 -- aggregate can be written. In that case, rewrite the assignment as a
464 -- null statement, a length check has already been emitted to verify
465 -- that the range of the left-hand side is empty.
467 -- Note that this code is not executed if we had an assignment of
468 -- a string literal to a non-bit aligned component of a record, a
469 -- case which cannot be handled by the backend
471 elsif Nkind
(Rhs
) = N_String_Literal
then
472 if String_Length
(Strval
(Rhs
)) = 0
473 and then Is_Bit_Packed_Array
(L_Type
)
475 Rewrite
(N
, Make_Null_Statement
(Loc
));
481 -- If either operand is bit packed, then we need a loop, since we
482 -- can't be sure that the slice is byte aligned. Similarly, if either
483 -- operand is a possibly unaligned slice, then we need a loop (since
484 -- the back end cannot handle unaligned slices).
486 elsif Is_Bit_Packed_Array
(L_Type
)
487 or else Is_Bit_Packed_Array
(R_Type
)
488 or else Is_Possibly_Unaligned_Slice
(Lhs
)
489 or else Is_Possibly_Unaligned_Slice
(Rhs
)
491 Loop_Required
:= True;
493 -- If we are not bit-packed, and we have only one slice, then no
494 -- overlap is possible except in the parameter case, so we can let
495 -- the back end handle things.
497 elsif not (L_Slice
and R_Slice
) then
498 if Forwards_OK
(N
) then
503 -- If the right-hand side is a string literal, introduce a temporary
504 -- for it, for use in the generated loop that will follow.
506 if Nkind
(Rhs
) = N_String_Literal
then
508 Temp
: constant Entity_Id
:=
509 Make_Defining_Identifier
(Loc
, New_Internal_Name
('T'));
514 Make_Object_Declaration
(Loc
,
515 Defining_Identifier
=> Temp
,
516 Object_Definition
=> New_Occurrence_Of
(L_Type
, Loc
),
517 Expression
=> Relocate_Node
(Rhs
));
519 Insert_Action
(N
, Decl
);
520 Rewrite
(Rhs
, New_Occurrence_Of
(Temp
, Loc
));
521 R_Type
:= Etype
(Temp
);
525 -- Come here to complete the analysis
527 -- Loop_Required: Set to True if we know that a loop is required
528 -- regardless of overlap considerations.
530 -- Forwards_OK: Set to False if we already know that a forwards
531 -- move is not safe, else set to True.
533 -- Backwards_OK: Set to False if we already know that a backwards
534 -- move is not safe, else set to True
536 -- Our task at this stage is to complete the overlap analysis, which
537 -- can result in possibly setting Forwards_OK or Backwards_OK to
538 -- False, and then generating the final code, either by deciding
539 -- that it is OK after all to let Gigi handle it, or by generating
540 -- appropriate code in the front end.
543 L_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(L_Type
));
544 R_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(R_Type
));
546 Left_Lo
: constant Node_Id
:= Type_Low_Bound
(L_Index_Typ
);
547 Left_Hi
: constant Node_Id
:= Type_High_Bound
(L_Index_Typ
);
548 Right_Lo
: constant Node_Id
:= Type_Low_Bound
(R_Index_Typ
);
549 Right_Hi
: constant Node_Id
:= Type_High_Bound
(R_Index_Typ
);
551 Act_L_Array
: Node_Id
;
552 Act_R_Array
: Node_Id
;
558 Cresult
: Compare_Result
;
561 -- Get the expressions for the arrays. If we are dealing with a
562 -- private type, then convert to the underlying type. We can do
563 -- direct assignments to an array that is a private type, but
564 -- we cannot assign to elements of the array without this extra
565 -- unchecked conversion.
567 if Nkind
(Act_Lhs
) = N_Slice
then
568 Larray
:= Prefix
(Act_Lhs
);
572 if Is_Private_Type
(Etype
(Larray
)) then
575 (Underlying_Type
(Etype
(Larray
)), Larray
);
579 if Nkind
(Act_Rhs
) = N_Slice
then
580 Rarray
:= Prefix
(Act_Rhs
);
584 if Is_Private_Type
(Etype
(Rarray
)) then
587 (Underlying_Type
(Etype
(Rarray
)), Rarray
);
591 -- If both sides are slices, we must figure out whether
592 -- it is safe to do the move in one direction or the other
593 -- It is always safe if there is a change of representation
594 -- since obviously two arrays with different representations
595 -- cannot possibly overlap.
597 if (not Crep
) and L_Slice
and R_Slice
then
598 Act_L_Array
:= Get_Referenced_Object
(Prefix
(Act_Lhs
));
599 Act_R_Array
:= Get_Referenced_Object
(Prefix
(Act_Rhs
));
601 -- If both left and right hand arrays are entity names, and
602 -- refer to different entities, then we know that the move
603 -- is safe (the two storage areas are completely disjoint).
605 if Is_Entity_Name
(Act_L_Array
)
606 and then Is_Entity_Name
(Act_R_Array
)
607 and then Entity
(Act_L_Array
) /= Entity
(Act_R_Array
)
611 -- Otherwise, we assume the worst, which is that the two
612 -- arrays are the same array. There is no need to check if
613 -- we know that is the case, because if we don't know it,
614 -- we still have to assume it!
616 -- Generally if the same array is involved, then we have
617 -- an overlapping case. We will have to really assume the
618 -- worst (i.e. set neither of the OK flags) unless we can
619 -- determine the lower or upper bounds at compile time and
623 Cresult
:= Compile_Time_Compare
(Left_Lo
, Right_Lo
);
625 if Cresult
= Unknown
then
626 Cresult
:= Compile_Time_Compare
(Left_Hi
, Right_Hi
);
630 when LT | LE | EQ
=> Set_Backwards_OK
(N
, False);
631 when GT | GE
=> Set_Forwards_OK
(N
, False);
632 when NE | Unknown
=> Set_Backwards_OK
(N
, False);
633 Set_Forwards_OK
(N
, False);
638 -- If after that analysis, Forwards_OK is still True, and
639 -- Loop_Required is False, meaning that we have not discovered
640 -- some non-overlap reason for requiring a loop, then we can
641 -- still let gigi handle it.
643 if not Loop_Required
then
644 if Forwards_OK
(N
) then
648 -- Here is where a memmove would be appropriate ???
652 -- At this stage we have to generate an explicit loop, and
653 -- we have the following cases:
655 -- Forwards_OK = True
657 -- Rnn : right_index := right_index'First;
658 -- for Lnn in left-index loop
659 -- left (Lnn) := right (Rnn);
660 -- Rnn := right_index'Succ (Rnn);
663 -- Note: the above code MUST be analyzed with checks off,
664 -- because otherwise the Succ could overflow. But in any
665 -- case this is more efficient!
667 -- Forwards_OK = False, Backwards_OK = True
669 -- Rnn : right_index := right_index'Last;
670 -- for Lnn in reverse left-index loop
671 -- left (Lnn) := right (Rnn);
672 -- Rnn := right_index'Pred (Rnn);
675 -- Note: the above code MUST be analyzed with checks off,
676 -- because otherwise the Pred could overflow. But in any
677 -- case this is more efficient!
679 -- Forwards_OK = Backwards_OK = False
681 -- This only happens if we have the same array on each side. It is
682 -- possible to create situations using overlays that violate this,
683 -- but we simply do not promise to get this "right" in this case.
685 -- There are two possible subcases. If the No_Implicit_Conditionals
686 -- restriction is set, then we generate the following code:
689 -- T : constant <operand-type> := rhs;
694 -- If implicit conditionals are permitted, then we generate:
696 -- if Left_Lo <= Right_Lo then
697 -- <code for Forwards_OK = True above>
699 -- <code for Backwards_OK = True above>
702 -- Cases where either Forwards_OK or Backwards_OK is true
704 if Forwards_OK
(N
) or else Backwards_OK
(N
) then
705 if Controlled_Type
(Component_Type
(L_Type
))
706 and then Base_Type
(L_Type
) = Base_Type
(R_Type
)
708 and then not No_Ctrl_Actions
(N
)
711 Proc
: constant Entity_Id
:=
712 TSS
(Base_Type
(L_Type
), TSS_Slice_Assign
);
716 Apply_Dereference
(Larray
);
717 Apply_Dereference
(Rarray
);
718 Actuals
:= New_List
(
719 Duplicate_Subexpr
(Larray
, Name_Req
=> True),
720 Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
721 Duplicate_Subexpr
(Left_Lo
, Name_Req
=> True),
722 Duplicate_Subexpr
(Left_Hi
, Name_Req
=> True),
723 Duplicate_Subexpr
(Right_Lo
, Name_Req
=> True),
724 Duplicate_Subexpr
(Right_Hi
, Name_Req
=> True));
728 Boolean_Literals
(not Forwards_OK
(N
)), Loc
));
731 Make_Procedure_Call_Statement
(Loc
,
732 Name
=> New_Reference_To
(Proc
, Loc
),
733 Parameter_Associations
=> Actuals
));
738 Expand_Assign_Array_Loop
739 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
740 Rev
=> not Forwards_OK
(N
)));
743 -- Case of both are false with No_Implicit_Conditionals
745 elsif Restriction_Active
(No_Implicit_Conditionals
) then
747 T
: constant Entity_Id
:=
748 Make_Defining_Identifier
(Loc
, Chars
=> Name_T
);
752 Make_Block_Statement
(Loc
,
753 Declarations
=> New_List
(
754 Make_Object_Declaration
(Loc
,
755 Defining_Identifier
=> T
,
756 Constant_Present
=> True,
758 New_Occurrence_Of
(Etype
(Rhs
), Loc
),
759 Expression
=> Relocate_Node
(Rhs
))),
761 Handled_Statement_Sequence
=>
762 Make_Handled_Sequence_Of_Statements
(Loc
,
763 Statements
=> New_List
(
764 Make_Assignment_Statement
(Loc
,
765 Name
=> Relocate_Node
(Lhs
),
766 Expression
=> New_Occurrence_Of
(T
, Loc
))))));
769 -- Case of both are false with implicit conditionals allowed
772 -- Before we generate this code, we must ensure that the
773 -- left and right side array types are defined. They may
774 -- be itypes, and we cannot let them be defined inside the
775 -- if, since the first use in the then may not be executed.
777 Ensure_Defined
(L_Type
, N
);
778 Ensure_Defined
(R_Type
, N
);
780 -- We normally compare addresses to find out which way round
781 -- to do the loop, since this is realiable, and handles the
782 -- cases of parameters, conversions etc. But we can't do that
783 -- in the bit packed case or the Java VM case, because addresses
786 if not Is_Bit_Packed_Array
(L_Type
) and then not Java_VM
then
790 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
791 Make_Attribute_Reference
(Loc
,
793 Make_Indexed_Component
(Loc
,
795 Duplicate_Subexpr_Move_Checks
(Larray
, True),
796 Expressions
=> New_List
(
797 Make_Attribute_Reference
(Loc
,
801 Attribute_Name
=> Name_First
))),
802 Attribute_Name
=> Name_Address
)),
805 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
806 Make_Attribute_Reference
(Loc
,
808 Make_Indexed_Component
(Loc
,
810 Duplicate_Subexpr_Move_Checks
(Rarray
, True),
811 Expressions
=> New_List
(
812 Make_Attribute_Reference
(Loc
,
816 Attribute_Name
=> Name_First
))),
817 Attribute_Name
=> Name_Address
)));
819 -- For the bit packed and Java VM cases we use the bounds.
820 -- That's OK, because we don't have to worry about parameters,
821 -- since they cannot cause overlap. Perhaps we should worry
822 -- about weird slice conversions ???
825 -- Copy the bounds and reset the Analyzed flag, because the
826 -- bounds of the index type itself may be universal, and must
827 -- must be reaanalyzed to acquire the proper type for Gigi.
829 Cleft_Lo
:= New_Copy_Tree
(Left_Lo
);
830 Cright_Lo
:= New_Copy_Tree
(Right_Lo
);
831 Set_Analyzed
(Cleft_Lo
, False);
832 Set_Analyzed
(Cright_Lo
, False);
836 Left_Opnd
=> Cleft_Lo
,
837 Right_Opnd
=> Cright_Lo
);
840 if Controlled_Type
(Component_Type
(L_Type
))
841 and then Base_Type
(L_Type
) = Base_Type
(R_Type
)
843 and then not No_Ctrl_Actions
(N
)
846 -- Call TSS procedure for array assignment, passing the
847 -- the explicit bounds of right and left hand sides.
850 Proc
: constant Node_Id
:=
851 TSS
(Base_Type
(L_Type
), TSS_Slice_Assign
);
855 Apply_Dereference
(Larray
);
856 Apply_Dereference
(Rarray
);
857 Actuals
:= New_List
(
858 Duplicate_Subexpr
(Larray
, Name_Req
=> True),
859 Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
860 Duplicate_Subexpr
(Left_Lo
, Name_Req
=> True),
861 Duplicate_Subexpr
(Left_Hi
, Name_Req
=> True),
862 Duplicate_Subexpr
(Right_Lo
, Name_Req
=> True),
863 Duplicate_Subexpr
(Right_Hi
, Name_Req
=> True));
867 Right_Opnd
=> Condition
));
870 Make_Procedure_Call_Statement
(Loc
,
871 Name
=> New_Reference_To
(Proc
, Loc
),
872 Parameter_Associations
=> Actuals
));
877 Make_Implicit_If_Statement
(N
,
878 Condition
=> Condition
,
880 Then_Statements
=> New_List
(
881 Expand_Assign_Array_Loop
882 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
885 Else_Statements
=> New_List
(
886 Expand_Assign_Array_Loop
887 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
892 Analyze
(N
, Suppress
=> All_Checks
);
896 when RE_Not_Available
=>
898 end Expand_Assign_Array
;
900 ------------------------------
901 -- Expand_Assign_Array_Loop --
902 ------------------------------
904 -- The following is an example of the loop generated for the case of
905 -- a two-dimensional array:
910 -- for L1b in 1 .. 100 loop
914 -- for L3b in 1 .. 100 loop
915 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
916 -- R4b := Tm1X2'succ(R4b);
919 -- R2b := Tm1X1'succ(R2b);
923 -- Here Rev is False, and Tm1Xn are the subscript types for the right
924 -- hand side. The declarations of R2b and R4b are inserted before the
925 -- original assignment statement.
927 function Expand_Assign_Array_Loop
934 Rev
: Boolean) return Node_Id
936 Loc
: constant Source_Ptr
:= Sloc
(N
);
938 Lnn
: array (1 .. Ndim
) of Entity_Id
;
939 Rnn
: array (1 .. Ndim
) of Entity_Id
;
940 -- Entities used as subscripts on left and right sides
942 L_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
943 R_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
944 -- Left and right index types
956 F_Or_L
:= Name_First
;
960 -- Setup index types and subscript entities
967 L_Index
:= First_Index
(L_Type
);
968 R_Index
:= First_Index
(R_Type
);
970 for J
in 1 .. Ndim
loop
972 Make_Defining_Identifier
(Loc
,
973 Chars
=> New_Internal_Name
('L'));
976 Make_Defining_Identifier
(Loc
,
977 Chars
=> New_Internal_Name
('R'));
979 L_Index_Type
(J
) := Etype
(L_Index
);
980 R_Index_Type
(J
) := Etype
(R_Index
);
982 Next_Index
(L_Index
);
983 Next_Index
(R_Index
);
987 -- Now construct the assignment statement
990 ExprL
: constant List_Id
:= New_List
;
991 ExprR
: constant List_Id
:= New_List
;
994 for J
in 1 .. Ndim
loop
995 Append_To
(ExprL
, New_Occurrence_Of
(Lnn
(J
), Loc
));
996 Append_To
(ExprR
, New_Occurrence_Of
(Rnn
(J
), Loc
));
1000 Make_Assignment_Statement
(Loc
,
1002 Make_Indexed_Component
(Loc
,
1003 Prefix
=> Duplicate_Subexpr
(Larray
, Name_Req
=> True),
1004 Expressions
=> ExprL
),
1006 Make_Indexed_Component
(Loc
,
1007 Prefix
=> Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
1008 Expressions
=> ExprR
));
1010 -- We set assignment OK, since there are some cases, e.g. in object
1011 -- declarations, where we are actually assigning into a constant.
1012 -- If there really is an illegality, it was caught long before now,
1013 -- and was flagged when the original assignment was analyzed.
1015 Set_Assignment_OK
(Name
(Assign
));
1017 -- Propagate the No_Ctrl_Actions flag to individual assignments
1019 Set_No_Ctrl_Actions
(Assign
, No_Ctrl_Actions
(N
));
1022 -- Now construct the loop from the inside out, with the last subscript
1023 -- varying most rapidly. Note that Assign is first the raw assignment
1024 -- statement, and then subsequently the loop that wraps it up.
1026 for J
in reverse 1 .. Ndim
loop
1028 Make_Block_Statement
(Loc
,
1029 Declarations
=> New_List
(
1030 Make_Object_Declaration
(Loc
,
1031 Defining_Identifier
=> Rnn
(J
),
1032 Object_Definition
=>
1033 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1035 Make_Attribute_Reference
(Loc
,
1036 Prefix
=> New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1037 Attribute_Name
=> F_Or_L
))),
1039 Handled_Statement_Sequence
=>
1040 Make_Handled_Sequence_Of_Statements
(Loc
,
1041 Statements
=> New_List
(
1042 Make_Implicit_Loop_Statement
(N
,
1044 Make_Iteration_Scheme
(Loc
,
1045 Loop_Parameter_Specification
=>
1046 Make_Loop_Parameter_Specification
(Loc
,
1047 Defining_Identifier
=> Lnn
(J
),
1048 Reverse_Present
=> Rev
,
1049 Discrete_Subtype_Definition
=>
1050 New_Reference_To
(L_Index_Type
(J
), Loc
))),
1052 Statements
=> New_List
(
1055 Make_Assignment_Statement
(Loc
,
1056 Name
=> New_Occurrence_Of
(Rnn
(J
), Loc
),
1058 Make_Attribute_Reference
(Loc
,
1060 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1061 Attribute_Name
=> S_Or_P
,
1062 Expressions
=> New_List
(
1063 New_Occurrence_Of
(Rnn
(J
), Loc
)))))))));
1067 end Expand_Assign_Array_Loop
;
1069 --------------------------
1070 -- Expand_Assign_Record --
1071 --------------------------
1073 -- The only processing required is in the change of representation
1074 -- case, where we must expand the assignment to a series of field
1075 -- by field assignments.
1077 procedure Expand_Assign_Record
(N
: Node_Id
) is
1078 Lhs
: constant Node_Id
:= Name
(N
);
1079 Rhs
: Node_Id
:= Expression
(N
);
1082 -- If change of representation, then extract the real right hand
1083 -- side from the type conversion, and proceed with component-wise
1084 -- assignment, since the two types are not the same as far as the
1085 -- back end is concerned.
1087 if Change_Of_Representation
(N
) then
1088 Rhs
:= Expression
(Rhs
);
1090 -- If this may be a case of a large bit aligned component, then
1091 -- proceed with component-wise assignment, to avoid possible
1092 -- clobbering of other components sharing bits in the first or
1093 -- last byte of the component to be assigned.
1095 elsif Possible_Bit_Aligned_Component
(Lhs
)
1097 Possible_Bit_Aligned_Component
(Rhs
)
1101 -- If neither condition met, then nothing special to do, the back end
1102 -- can handle assignment of the entire component as a single entity.
1108 -- At this stage we know that we must do a component wise assignment
1111 Loc
: constant Source_Ptr
:= Sloc
(N
);
1112 R_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Rhs
));
1113 L_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Lhs
));
1114 Decl
: constant Node_Id
:= Declaration_Node
(R_Typ
);
1118 function Find_Component
1120 Comp
: Entity_Id
) return Entity_Id
;
1121 -- Find the component with the given name in the underlying record
1122 -- declaration for Typ. We need to use the actual entity because
1123 -- the type may be private and resolution by identifier alone would
1126 function Make_Component_List_Assign
1128 U_U
: Boolean := False) return List_Id
;
1129 -- Returns a sequence of statements to assign the components that
1130 -- are referenced in the given component list. The flag U_U is
1131 -- used to force the usage of the inferred value of the variant
1132 -- part expression as the switch for the generated case statement.
1134 function Make_Field_Assign
1136 U_U
: Boolean := False) return Node_Id
;
1137 -- Given C, the entity for a discriminant or component, build an
1138 -- assignment for the corresponding field values. The flag U_U
1139 -- signals the presence of an Unchecked_Union and forces the usage
1140 -- of the inferred discriminant value of C as the right hand side
1141 -- of the assignment.
1143 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
;
1144 -- Given CI, a component items list, construct series of statements
1145 -- for fieldwise assignment of the corresponding components.
1147 --------------------
1148 -- Find_Component --
1149 --------------------
1151 function Find_Component
1153 Comp
: Entity_Id
) return Entity_Id
1155 Utyp
: constant Entity_Id
:= Underlying_Type
(Typ
);
1159 C
:= First_Entity
(Utyp
);
1161 while Present
(C
) loop
1162 if Chars
(C
) = Chars
(Comp
) then
1168 raise Program_Error
;
1171 --------------------------------
1172 -- Make_Component_List_Assign --
1173 --------------------------------
1175 function Make_Component_List_Assign
1177 U_U
: Boolean := False) return List_Id
1179 CI
: constant List_Id
:= Component_Items
(CL
);
1180 VP
: constant Node_Id
:= Variant_Part
(CL
);
1190 Result
:= Make_Field_Assigns
(CI
);
1192 if Present
(VP
) then
1194 V
:= First_Non_Pragma
(Variants
(VP
));
1196 while Present
(V
) loop
1199 DC
:= First
(Discrete_Choices
(V
));
1200 while Present
(DC
) loop
1201 Append_To
(DCH
, New_Copy_Tree
(DC
));
1206 Make_Case_Statement_Alternative
(Loc
,
1207 Discrete_Choices
=> DCH
,
1209 Make_Component_List_Assign
(Component_List
(V
))));
1210 Next_Non_Pragma
(V
);
1213 -- If we have an Unchecked_Union, use the value of the inferred
1214 -- discriminant of the variant part expression as the switch
1215 -- for the case statement. The case statement may later be
1220 New_Copy
(Get_Discriminant_Value
(
1223 Discriminant_Constraint
(Etype
(Rhs
))));
1226 Make_Selected_Component
(Loc
,
1227 Prefix
=> Duplicate_Subexpr
(Rhs
),
1229 Make_Identifier
(Loc
, Chars
(Name
(VP
))));
1233 Make_Case_Statement
(Loc
,
1235 Alternatives
=> Alts
));
1239 end Make_Component_List_Assign
;
1241 -----------------------
1242 -- Make_Field_Assign --
1243 -----------------------
1245 function Make_Field_Assign
1247 U_U
: Boolean := False) return Node_Id
1253 -- In the case of an Unchecked_Union, use the discriminant
1254 -- constraint value as on the right hand side of the assignment.
1258 New_Copy
(Get_Discriminant_Value
(C
,
1260 Discriminant_Constraint
(Etype
(Rhs
))));
1263 Make_Selected_Component
(Loc
,
1264 Prefix
=> Duplicate_Subexpr
(Rhs
),
1265 Selector_Name
=> New_Occurrence_Of
(C
, Loc
));
1269 Make_Assignment_Statement
(Loc
,
1271 Make_Selected_Component
(Loc
,
1272 Prefix
=> Duplicate_Subexpr
(Lhs
),
1274 New_Occurrence_Of
(Find_Component
(L_Typ
, C
), Loc
)),
1275 Expression
=> Expr
);
1277 -- Set Assignment_OK, so discriminants can be assigned
1279 Set_Assignment_OK
(Name
(A
), True);
1281 end Make_Field_Assign
;
1283 ------------------------
1284 -- Make_Field_Assigns --
1285 ------------------------
1287 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
is
1294 while Present
(Item
) loop
1295 if Nkind
(Item
) = N_Component_Declaration
then
1297 (Result
, Make_Field_Assign
(Defining_Identifier
(Item
)));
1304 end Make_Field_Assigns
;
1306 -- Start of processing for Expand_Assign_Record
1309 -- Note that we use the base types for this processing. This results
1310 -- in some extra work in the constrained case, but the change of
1311 -- representation case is so unusual that it is not worth the effort.
1313 -- First copy the discriminants. This is done unconditionally. It
1314 -- is required in the unconstrained left side case, and also in the
1315 -- case where this assignment was constructed during the expansion
1316 -- of a type conversion (since initialization of discriminants is
1317 -- suppressed in this case). It is unnecessary but harmless in
1320 if Has_Discriminants
(L_Typ
) then
1321 F
:= First_Discriminant
(R_Typ
);
1322 while Present
(F
) loop
1324 if Is_Unchecked_Union
(Base_Type
(R_Typ
)) then
1325 Insert_Action
(N
, Make_Field_Assign
(F
, True));
1327 Insert_Action
(N
, Make_Field_Assign
(F
));
1330 Next_Discriminant
(F
);
1334 -- We know the underlying type is a record, but its current view
1335 -- may be private. We must retrieve the usable record declaration.
1337 if Nkind
(Decl
) = N_Private_Type_Declaration
1338 and then Present
(Full_View
(R_Typ
))
1340 RDef
:= Type_Definition
(Declaration_Node
(Full_View
(R_Typ
)));
1342 RDef
:= Type_Definition
(Decl
);
1345 if Nkind
(RDef
) = N_Record_Definition
1346 and then Present
(Component_List
(RDef
))
1349 if Is_Unchecked_Union
(R_Typ
) then
1351 Make_Component_List_Assign
(Component_List
(RDef
), True));
1354 (N
, Make_Component_List_Assign
(Component_List
(RDef
)));
1357 Rewrite
(N
, Make_Null_Statement
(Loc
));
1361 end Expand_Assign_Record
;
1363 -----------------------------------
1364 -- Expand_N_Assignment_Statement --
1365 -----------------------------------
1367 -- This procedure implements various cases where an assignment statement
1368 -- cannot just be passed on to the back end in untransformed state.
1370 procedure Expand_N_Assignment_Statement
(N
: Node_Id
) is
1371 Loc
: constant Source_Ptr
:= Sloc
(N
);
1372 Lhs
: constant Node_Id
:= Name
(N
);
1373 Rhs
: constant Node_Id
:= Expression
(N
);
1374 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Lhs
));
1378 -- First deal with generation of range check if required. For now
1379 -- we do this only for discrete types.
1381 if Do_Range_Check
(Rhs
)
1382 and then Is_Discrete_Type
(Typ
)
1384 Set_Do_Range_Check
(Rhs
, False);
1385 Generate_Range_Check
(Rhs
, Typ
, CE_Range_Check_Failed
);
1388 -- Check for a special case where a high level transformation is
1389 -- required. If we have either of:
1394 -- where P is a reference to a bit packed array, then we have to unwind
1395 -- the assignment. The exact meaning of being a reference to a bit
1396 -- packed array is as follows:
1398 -- An indexed component whose prefix is a bit packed array is a
1399 -- reference to a bit packed array.
1401 -- An indexed component or selected component whose prefix is a
1402 -- reference to a bit packed array is itself a reference ot a
1403 -- bit packed array.
1405 -- The required transformation is
1407 -- Tnn : prefix_type := P;
1408 -- Tnn.field := rhs;
1413 -- Tnn : prefix_type := P;
1414 -- Tnn (subscr) := rhs;
1417 -- Since P is going to be evaluated more than once, any subscripts
1418 -- in P must have their evaluation forced.
1420 if (Nkind
(Lhs
) = N_Indexed_Component
1422 Nkind
(Lhs
) = N_Selected_Component
)
1423 and then Is_Ref_To_Bit_Packed_Array
(Prefix
(Lhs
))
1426 BPAR_Expr
: constant Node_Id
:= Relocate_Node
(Prefix
(Lhs
));
1427 BPAR_Typ
: constant Entity_Id
:= Etype
(BPAR_Expr
);
1428 Tnn
: constant Entity_Id
:=
1429 Make_Defining_Identifier
(Loc
,
1430 Chars
=> New_Internal_Name
('T'));
1433 -- Insert the post assignment first, because we want to copy
1434 -- the BPAR_Expr tree before it gets analyzed in the context
1435 -- of the pre assignment. Note that we do not analyze the
1436 -- post assignment yet (we cannot till we have completed the
1437 -- analysis of the pre assignment). As usual, the analysis
1438 -- of this post assignment will happen on its own when we
1439 -- "run into" it after finishing the current assignment.
1442 Make_Assignment_Statement
(Loc
,
1443 Name
=> New_Copy_Tree
(BPAR_Expr
),
1444 Expression
=> New_Occurrence_Of
(Tnn
, Loc
)));
1446 -- At this stage BPAR_Expr is a reference to a bit packed
1447 -- array where the reference was not expanded in the original
1448 -- tree, since it was on the left side of an assignment. But
1449 -- in the pre-assignment statement (the object definition),
1450 -- BPAR_Expr will end up on the right hand side, and must be
1451 -- reexpanded. To achieve this, we reset the analyzed flag
1452 -- of all selected and indexed components down to the actual
1453 -- indexed component for the packed array.
1457 Set_Analyzed
(Exp
, False);
1459 if Nkind
(Exp
) = N_Selected_Component
1461 Nkind
(Exp
) = N_Indexed_Component
1463 Exp
:= Prefix
(Exp
);
1469 -- Now we can insert and analyze the pre-assignment
1471 -- If the right-hand side requires a transient scope, it has
1472 -- already been placed on the stack. However, the declaration is
1473 -- inserted in the tree outside of this scope, and must reflect
1474 -- the proper scope for its variable. This awkward bit is forced
1475 -- by the stricter scope discipline imposed by GCC 2.97.
1478 Uses_Transient_Scope
: constant Boolean :=
1480 and then N
= Node_To_Be_Wrapped
;
1483 if Uses_Transient_Scope
then
1484 New_Scope
(Scope
(Current_Scope
));
1487 Insert_Before_And_Analyze
(N
,
1488 Make_Object_Declaration
(Loc
,
1489 Defining_Identifier
=> Tnn
,
1490 Object_Definition
=> New_Occurrence_Of
(BPAR_Typ
, Loc
),
1491 Expression
=> BPAR_Expr
));
1493 if Uses_Transient_Scope
then
1498 -- Now fix up the original assignment and continue processing
1500 Rewrite
(Prefix
(Lhs
),
1501 New_Occurrence_Of
(Tnn
, Loc
));
1503 -- We do not need to reanalyze that assignment, and we do not need
1504 -- to worry about references to the temporary, but we do need to
1505 -- make sure that the temporary is not marked as a true constant
1506 -- since we now have a generate assignment to it!
1508 Set_Is_True_Constant
(Tnn
, False);
1512 -- When we have the appropriate type of aggregate in the
1513 -- expression (it has been determined during analysis of the
1514 -- aggregate by setting the delay flag), let's perform in place
1515 -- assignment and thus avoid creating a temporay.
1517 if Is_Delayed_Aggregate
(Rhs
) then
1518 Convert_Aggr_In_Assignment
(N
);
1519 Rewrite
(N
, Make_Null_Statement
(Loc
));
1524 -- Apply discriminant check if required. If Lhs is an access type
1525 -- to a designated type with discriminants, we must always check.
1527 if Has_Discriminants
(Etype
(Lhs
)) then
1529 -- Skip discriminant check if change of representation. Will be
1530 -- done when the change of representation is expanded out.
1532 if not Change_Of_Representation
(N
) then
1533 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
), Lhs
);
1536 -- If the type is private without discriminants, and the full type
1537 -- has discriminants (necessarily with defaults) a check may still be
1538 -- necessary if the Lhs is aliased. The private determinants must be
1539 -- visible to build the discriminant constraints.
1541 -- Only an explicit dereference that comes from source indicates
1542 -- aliasing. Access to formals of protected operations and entries
1543 -- create dereferences but are not semantic aliasings.
1545 elsif Is_Private_Type
(Etype
(Lhs
))
1546 and then Has_Discriminants
(Typ
)
1547 and then Nkind
(Lhs
) = N_Explicit_Dereference
1548 and then Comes_From_Source
(Lhs
)
1551 Lt
: constant Entity_Id
:= Etype
(Lhs
);
1553 Set_Etype
(Lhs
, Typ
);
1554 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
1555 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
1556 Set_Etype
(Lhs
, Lt
);
1559 -- If the Lhs has a private type with unknown discriminants, it
1560 -- may have a full view with discriminants, but those are nameable
1561 -- only in the underlying type, so convert the Rhs to it before
1562 -- potential checking.
1564 elsif Has_Unknown_Discriminants
(Base_Type
(Etype
(Lhs
)))
1565 and then Has_Discriminants
(Typ
)
1567 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
1568 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
1570 -- In the access type case, we need the same discriminant check,
1571 -- and also range checks if we have an access to constrained array.
1573 elsif Is_Access_Type
(Etype
(Lhs
))
1574 and then Is_Constrained
(Designated_Type
(Etype
(Lhs
)))
1576 if Has_Discriminants
(Designated_Type
(Etype
(Lhs
))) then
1578 -- Skip discriminant check if change of representation. Will be
1579 -- done when the change of representation is expanded out.
1581 if not Change_Of_Representation
(N
) then
1582 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
));
1585 elsif Is_Array_Type
(Designated_Type
(Etype
(Lhs
))) then
1586 Apply_Range_Check
(Rhs
, Etype
(Lhs
));
1588 if Is_Constrained
(Etype
(Lhs
)) then
1589 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
1592 if Nkind
(Rhs
) = N_Allocator
then
1594 Target_Typ
: constant Entity_Id
:= Etype
(Expression
(Rhs
));
1595 C_Es
: Check_Result
;
1602 Etype
(Designated_Type
(Etype
(Lhs
))));
1614 -- Apply range check for access type case
1616 elsif Is_Access_Type
(Etype
(Lhs
))
1617 and then Nkind
(Rhs
) = N_Allocator
1618 and then Nkind
(Expression
(Rhs
)) = N_Qualified_Expression
1620 Analyze_And_Resolve
(Expression
(Rhs
));
1622 (Expression
(Rhs
), Designated_Type
(Etype
(Lhs
)));
1625 -- Ada 2005 (AI-231): Generate the run-time check
1627 if Is_Access_Type
(Typ
)
1628 and then Can_Never_Be_Null
(Etype
(Lhs
))
1629 and then not Can_Never_Be_Null
(Etype
(Rhs
))
1631 Apply_Constraint_Check
(Rhs
, Etype
(Lhs
));
1634 -- Case of assignment to a bit packed array element
1636 if Nkind
(Lhs
) = N_Indexed_Component
1637 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Lhs
)))
1639 Expand_Bit_Packed_Element_Set
(N
);
1642 elsif Is_Tagged_Type
(Typ
)
1643 or else (Controlled_Type
(Typ
) and then not Is_Array_Type
(Typ
))
1645 Tagged_Case
: declare
1646 L
: List_Id
:= No_List
;
1647 Expand_Ctrl_Actions
: constant Boolean := not No_Ctrl_Actions
(N
);
1650 -- In the controlled case, we need to make sure that function
1651 -- calls are evaluated before finalizing the target. In all
1652 -- cases, it makes the expansion easier if the side-effects
1653 -- are removed first.
1655 Remove_Side_Effects
(Lhs
);
1656 Remove_Side_Effects
(Rhs
);
1658 -- Avoid recursion in the mechanism
1662 -- If dispatching assignment, we need to dispatch to _assign
1664 if Is_Class_Wide_Type
(Typ
)
1666 -- If the type is tagged, we may as well use the predefined
1667 -- primitive assignment. This avoids inlining a lot of code
1668 -- and in the class-wide case, the assignment is replaced by
1669 -- dispatch call to _assign. Note that this cannot be done
1670 -- when discriminant checks are locally suppressed (as in
1671 -- extension aggregate expansions) because otherwise the
1672 -- discriminant check will be performed within the _assign
1673 -- call. It is also suppressed for assignmments created by the
1674 -- expander that correspond to initializations, where we do
1675 -- want to copy the tag (No_Ctrl_Actions flag set True).
1676 -- by the expander and we do not need to mess with tags ever
1677 -- (Expand_Ctrl_Actions flag is set True in this case).
1679 or else (Is_Tagged_Type
(Typ
)
1680 and then Chars
(Current_Scope
) /= Name_uAssign
1681 and then Expand_Ctrl_Actions
1682 and then not Discriminant_Checks_Suppressed
(Empty
))
1684 -- Fetch the primitive op _assign and proper type to call
1685 -- it. Because of possible conflits between private and
1686 -- full view the proper type is fetched directly from the
1687 -- operation profile.
1690 Op
: constant Entity_Id
:=
1691 Find_Prim_Op
(Typ
, Name_uAssign
);
1692 F_Typ
: Entity_Id
:= Etype
(First_Formal
(Op
));
1695 -- If the assignment is dispatching, make sure to use the
1698 if Is_Class_Wide_Type
(Typ
) then
1699 F_Typ
:= Class_Wide_Type
(F_Typ
);
1704 -- In case of assignment to a class-wide tagged type, before
1705 -- the assignment we generate run-time check to ensure that
1706 -- the tag of the Target is covered by the tag of the source
1708 if Is_Class_Wide_Type
(Typ
)
1709 and then Is_Tagged_Type
(Typ
)
1710 and then Is_Tagged_Type
(Underlying_Type
(Etype
(Rhs
)))
1713 Make_Raise_Constraint_Error
(Loc
,
1716 Make_Function_Call
(Loc
,
1717 Name
=> New_Reference_To
1718 (RTE
(RE_CW_Membership
), Loc
),
1719 Parameter_Associations
=> New_List
(
1720 Make_Selected_Component
(Loc
,
1722 Duplicate_Subexpr
(Lhs
),
1724 Make_Identifier
(Loc
, Name_uTag
)),
1725 Make_Selected_Component
(Loc
,
1727 Duplicate_Subexpr
(Rhs
),
1729 Make_Identifier
(Loc
, Name_uTag
))))),
1730 Reason
=> CE_Tag_Check_Failed
));
1734 Make_Procedure_Call_Statement
(Loc
,
1735 Name
=> New_Reference_To
(Op
, Loc
),
1736 Parameter_Associations
=> New_List
(
1737 Unchecked_Convert_To
(F_Typ
, Duplicate_Subexpr
(Lhs
)),
1738 Unchecked_Convert_To
(F_Typ
,
1739 Duplicate_Subexpr
(Rhs
)))));
1743 L
:= Make_Tag_Ctrl_Assignment
(N
);
1745 -- We can't afford to have destructive Finalization Actions
1746 -- in the Self assignment case, so if the target and the
1747 -- source are not obviously different, code is generated to
1748 -- avoid the self assignment case
1750 -- if lhs'address /= rhs'address then
1751 -- <code for controlled and/or tagged assignment>
1754 if not Statically_Different
(Lhs
, Rhs
)
1755 and then Expand_Ctrl_Actions
1758 Make_Implicit_If_Statement
(N
,
1762 Make_Attribute_Reference
(Loc
,
1763 Prefix
=> Duplicate_Subexpr
(Lhs
),
1764 Attribute_Name
=> Name_Address
),
1767 Make_Attribute_Reference
(Loc
,
1768 Prefix
=> Duplicate_Subexpr
(Rhs
),
1769 Attribute_Name
=> Name_Address
)),
1771 Then_Statements
=> L
));
1774 -- We need to set up an exception handler for implementing
1775 -- 7.6.1 (18). The remaining adjustments are tackled by the
1776 -- implementation of adjust for record_controllers (see
1779 -- This is skipped if we have no finalization
1781 if Expand_Ctrl_Actions
1782 and then not Restriction_Active
(No_Finalization
)
1785 Make_Block_Statement
(Loc
,
1786 Handled_Statement_Sequence
=>
1787 Make_Handled_Sequence_Of_Statements
(Loc
,
1789 Exception_Handlers
=> New_List
(
1790 Make_Exception_Handler
(Loc
,
1791 Exception_Choices
=>
1792 New_List
(Make_Others_Choice
(Loc
)),
1793 Statements
=> New_List
(
1794 Make_Raise_Program_Error
(Loc
,
1796 PE_Finalize_Raised_Exception
)
1802 Make_Block_Statement
(Loc
,
1803 Handled_Statement_Sequence
=>
1804 Make_Handled_Sequence_Of_Statements
(Loc
, Statements
=> L
)));
1806 -- If no restrictions on aborts, protect the whole assignement
1807 -- for controlled objects as per 9.8(11)
1809 if Controlled_Type
(Typ
)
1810 and then Expand_Ctrl_Actions
1811 and then Abort_Allowed
1814 Blk
: constant Entity_Id
:=
1816 (E_Block
, Current_Scope
, Sloc
(N
), 'B');
1819 Set_Scope
(Blk
, Current_Scope
);
1820 Set_Etype
(Blk
, Standard_Void_Type
);
1821 Set_Identifier
(N
, New_Occurrence_Of
(Blk
, Sloc
(N
)));
1823 Prepend_To
(L
, Build_Runtime_Call
(Loc
, RE_Abort_Defer
));
1824 Set_At_End_Proc
(Handled_Statement_Sequence
(N
),
1825 New_Occurrence_Of
(RTE
(RE_Abort_Undefer_Direct
), Loc
));
1826 Expand_At_End_Handler
1827 (Handled_Statement_Sequence
(N
), Blk
);
1831 -- N has been rewritten to a block statement for which it is
1832 -- known by construction that no checks are necessary: analyze
1833 -- it with all checks suppressed.
1835 Analyze
(N
, Suppress
=> All_Checks
);
1841 elsif Is_Array_Type
(Typ
) then
1843 Actual_Rhs
: Node_Id
:= Rhs
;
1846 while Nkind
(Actual_Rhs
) = N_Type_Conversion
1848 Nkind
(Actual_Rhs
) = N_Qualified_Expression
1850 Actual_Rhs
:= Expression
(Actual_Rhs
);
1853 Expand_Assign_Array
(N
, Actual_Rhs
);
1859 elsif Is_Record_Type
(Typ
) then
1860 Expand_Assign_Record
(N
);
1863 -- Scalar types. This is where we perform the processing related
1864 -- to the requirements of (RM 13.9.1(9-11)) concerning the handling
1865 -- of invalid scalar values.
1867 elsif Is_Scalar_Type
(Typ
) then
1869 -- Case where right side is known valid
1871 if Expr_Known_Valid
(Rhs
) then
1873 -- Here the right side is valid, so it is fine. The case to
1874 -- deal with is when the left side is a local variable reference
1875 -- whose value is not currently known to be valid. If this is
1876 -- the case, and the assignment appears in an unconditional
1877 -- context, then we can mark the left side as now being valid.
1879 if Is_Local_Variable_Reference
(Lhs
)
1880 and then not Is_Known_Valid
(Entity
(Lhs
))
1881 and then In_Unconditional_Context
(N
)
1883 Set_Is_Known_Valid
(Entity
(Lhs
), True);
1886 -- Case where right side may be invalid in the sense of the RM
1887 -- reference above. The RM does not require that we check for
1888 -- the validity on an assignment, but it does require that the
1889 -- assignment of an invalid value not cause erroneous behavior.
1891 -- The general approach in GNAT is to use the Is_Known_Valid flag
1892 -- to avoid the need for validity checking on assignments. However
1893 -- in some cases, we have to do validity checking in order to make
1894 -- sure that the setting of this flag is correct.
1897 -- Validate right side if we are validating copies
1899 if Validity_Checks_On
1900 and then Validity_Check_Copies
1904 -- We can propagate this to the left side where appropriate
1906 if Is_Local_Variable_Reference
(Lhs
)
1907 and then not Is_Known_Valid
(Entity
(Lhs
))
1908 and then In_Unconditional_Context
(N
)
1910 Set_Is_Known_Valid
(Entity
(Lhs
), True);
1913 -- Otherwise check to see what should be done
1915 -- If left side is a local variable, then we just set its
1916 -- flag to indicate that its value may no longer be valid,
1917 -- since we are copying a potentially invalid value.
1919 elsif Is_Local_Variable_Reference
(Lhs
) then
1920 Set_Is_Known_Valid
(Entity
(Lhs
), False);
1922 -- Check for case of a nonlocal variable on the left side
1923 -- which is currently known to be valid. In this case, we
1924 -- simply ensure that the right side is valid. We only play
1925 -- the game of copying validity status for local variables,
1926 -- since we are doing this statically, not by tracing the
1929 elsif Is_Entity_Name
(Lhs
)
1930 and then Is_Known_Valid
(Entity
(Lhs
))
1932 -- Note that the Ensure_Valid call is ignored if the
1933 -- Validity_Checking mode is set to none so we do not
1934 -- need to worry about that case here.
1938 -- In all other cases, we can safely copy an invalid value
1939 -- without worrying about the status of the left side. Since
1940 -- it is not a variable reference it will not be considered
1941 -- as being known to be valid in any case.
1949 -- Defend against invalid subscripts on left side if we are in
1950 -- standard validity checking mode. No need to do this if we
1951 -- are checking all subscripts.
1953 if Validity_Checks_On
1954 and then Validity_Check_Default
1955 and then not Validity_Check_Subscripts
1957 Check_Valid_Lvalue_Subscripts
(Lhs
);
1961 when RE_Not_Available
=>
1963 end Expand_N_Assignment_Statement
;
1965 ------------------------------
1966 -- Expand_N_Block_Statement --
1967 ------------------------------
1969 -- Encode entity names defined in block statement
1971 procedure Expand_N_Block_Statement
(N
: Node_Id
) is
1973 Qualify_Entity_Names
(N
);
1974 end Expand_N_Block_Statement
;
1976 -----------------------------
1977 -- Expand_N_Case_Statement --
1978 -----------------------------
1980 procedure Expand_N_Case_Statement
(N
: Node_Id
) is
1981 Loc
: constant Source_Ptr
:= Sloc
(N
);
1982 Expr
: constant Node_Id
:= Expression
(N
);
1990 -- Check for the situation where we know at compile time which
1991 -- branch will be taken
1993 if Compile_Time_Known_Value
(Expr
) then
1994 Alt
:= Find_Static_Alternative
(N
);
1996 -- Move the statements from this alternative after the case
1997 -- statement. They are already analyzed, so will be skipped
2000 Insert_List_After
(N
, Statements
(Alt
));
2002 -- That leaves the case statement as a shell. The alternative
2003 -- that will be executed is reset to a null list. So now we can
2004 -- kill the entire case statement.
2006 Kill_Dead_Code
(Expression
(N
));
2007 Kill_Dead_Code
(Alternatives
(N
));
2008 Rewrite
(N
, Make_Null_Statement
(Loc
));
2012 -- Here if the choice is not determined at compile time
2015 Last_Alt
: constant Node_Id
:= Last
(Alternatives
(N
));
2017 Others_Present
: Boolean;
2018 Others_Node
: Node_Id
;
2020 Then_Stms
: List_Id
;
2021 Else_Stms
: List_Id
;
2024 if Nkind
(First
(Discrete_Choices
(Last_Alt
))) = N_Others_Choice
then
2025 Others_Present
:= True;
2026 Others_Node
:= Last_Alt
;
2028 Others_Present
:= False;
2031 -- First step is to worry about possible invalid argument. The RM
2032 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
2033 -- outside the base range), then Constraint_Error must be raised.
2035 -- Case of validity check required (validity checks are on, the
2036 -- expression is not known to be valid, and the case statement
2037 -- comes from source -- no need to validity check internally
2038 -- generated case statements).
2040 if Validity_Check_Default
then
2041 Ensure_Valid
(Expr
);
2044 -- If there is only a single alternative, just replace it with
2045 -- the sequence of statements since obviously that is what is
2046 -- going to be executed in all cases.
2048 Len
:= List_Length
(Alternatives
(N
));
2051 -- We still need to evaluate the expression if it has any
2054 Remove_Side_Effects
(Expression
(N
));
2056 Insert_List_After
(N
, Statements
(First
(Alternatives
(N
))));
2058 -- That leaves the case statement as a shell. The alternative
2059 -- that will be executed is reset to a null list. So now we can
2060 -- kill the entire case statement.
2062 Kill_Dead_Code
(Expression
(N
));
2063 Rewrite
(N
, Make_Null_Statement
(Loc
));
2067 -- An optimization. If there are only two alternatives, and only
2068 -- a single choice, then rewrite the whole case statement as an
2069 -- if statement, since this can result in susbequent optimizations.
2070 -- This helps not only with case statements in the source of a
2071 -- simple form, but also with generated code (discriminant check
2072 -- functions in particular)
2075 Chlist
:= Discrete_Choices
(First
(Alternatives
(N
)));
2077 if List_Length
(Chlist
) = 1 then
2078 Choice
:= First
(Chlist
);
2080 Then_Stms
:= Statements
(First
(Alternatives
(N
)));
2081 Else_Stms
:= Statements
(Last
(Alternatives
(N
)));
2083 -- For TRUE, generate "expression", not expression = true
2085 if Nkind
(Choice
) = N_Identifier
2086 and then Entity
(Choice
) = Standard_True
2088 Cond
:= Expression
(N
);
2090 -- For FALSE, generate "expression" and switch then/else
2092 elsif Nkind
(Choice
) = N_Identifier
2093 and then Entity
(Choice
) = Standard_False
2095 Cond
:= Expression
(N
);
2096 Else_Stms
:= Statements
(First
(Alternatives
(N
)));
2097 Then_Stms
:= Statements
(Last
(Alternatives
(N
)));
2099 -- For a range, generate "expression in range"
2101 elsif Nkind
(Choice
) = N_Range
2102 or else (Nkind
(Choice
) = N_Attribute_Reference
2103 and then Attribute_Name
(Choice
) = Name_Range
)
2104 or else (Is_Entity_Name
(Choice
)
2105 and then Is_Type
(Entity
(Choice
)))
2106 or else Nkind
(Choice
) = N_Subtype_Indication
2110 Left_Opnd
=> Expression
(N
),
2111 Right_Opnd
=> Relocate_Node
(Choice
));
2113 -- For any other subexpression "expression = value"
2118 Left_Opnd
=> Expression
(N
),
2119 Right_Opnd
=> Relocate_Node
(Choice
));
2122 -- Now rewrite the case as an IF
2125 Make_If_Statement
(Loc
,
2127 Then_Statements
=> Then_Stms
,
2128 Else_Statements
=> Else_Stms
));
2134 -- If the last alternative is not an Others choice, replace it
2135 -- with an N_Others_Choice. Note that we do not bother to call
2136 -- Analyze on the modified case statement, since it's only effect
2137 -- would be to compute the contents of the Others_Discrete_Choices
2138 -- which is not needed by the back end anyway.
2140 -- The reason we do this is that the back end always needs some
2141 -- default for a switch, so if we have not supplied one in the
2142 -- processing above for validity checking, then we need to
2145 if not Others_Present
then
2146 Others_Node
:= Make_Others_Choice
(Sloc
(Last_Alt
));
2147 Set_Others_Discrete_Choices
2148 (Others_Node
, Discrete_Choices
(Last_Alt
));
2149 Set_Discrete_Choices
(Last_Alt
, New_List
(Others_Node
));
2152 end Expand_N_Case_Statement
;
2154 -----------------------------
2155 -- Expand_N_Exit_Statement --
2156 -----------------------------
2158 -- The only processing required is to deal with a possible C/Fortran
2159 -- boolean value used as the condition for the exit statement.
2161 procedure Expand_N_Exit_Statement
(N
: Node_Id
) is
2163 Adjust_Condition
(Condition
(N
));
2164 end Expand_N_Exit_Statement
;
2166 -----------------------------
2167 -- Expand_N_Goto_Statement --
2168 -----------------------------
2170 -- Add poll before goto if polling active
2172 procedure Expand_N_Goto_Statement
(N
: Node_Id
) is
2174 Generate_Poll_Call
(N
);
2175 end Expand_N_Goto_Statement
;
2177 ---------------------------
2178 -- Expand_N_If_Statement --
2179 ---------------------------
2181 -- First we deal with the case of C and Fortran convention boolean
2182 -- values, with zero/non-zero semantics.
2184 -- Second, we deal with the obvious rewriting for the cases where the
2185 -- condition of the IF is known at compile time to be True or False.
2187 -- Third, we remove elsif parts which have non-empty Condition_Actions
2188 -- and rewrite as independent if statements. For example:
2199 -- <<condition actions of y>>
2205 -- This rewriting is needed if at least one elsif part has a non-empty
2206 -- Condition_Actions list. We also do the same processing if there is
2207 -- a constant condition in an elsif part (in conjunction with the first
2208 -- processing step mentioned above, for the recursive call made to deal
2209 -- with the created inner if, this deals with properly optimizing the
2210 -- cases of constant elsif conditions).
2212 procedure Expand_N_If_Statement
(N
: Node_Id
) is
2213 Loc
: constant Source_Ptr
:= Sloc
(N
);
2219 Adjust_Condition
(Condition
(N
));
2221 -- The following loop deals with constant conditions for the IF. We
2222 -- need a loop because as we eliminate False conditions, we grab the
2223 -- first elsif condition and use it as the primary condition.
2225 while Compile_Time_Known_Value
(Condition
(N
)) loop
2227 -- If condition is True, we can simply rewrite the if statement
2228 -- now by replacing it by the series of then statements.
2230 if Is_True
(Expr_Value
(Condition
(N
))) then
2232 -- All the else parts can be killed
2234 Kill_Dead_Code
(Elsif_Parts
(N
));
2235 Kill_Dead_Code
(Else_Statements
(N
));
2237 Hed
:= Remove_Head
(Then_Statements
(N
));
2238 Insert_List_After
(N
, Then_Statements
(N
));
2242 -- If condition is False, then we can delete the condition and
2243 -- the Then statements
2246 -- We do not delete the condition if constant condition
2247 -- warnings are enabled, since otherwise we end up deleting
2248 -- the desired warning. Of course the backend will get rid
2249 -- of this True/False test anyway, so nothing is lost here.
2251 if not Constant_Condition_Warnings
then
2252 Kill_Dead_Code
(Condition
(N
));
2255 Kill_Dead_Code
(Then_Statements
(N
));
2257 -- If there are no elsif statements, then we simply replace
2258 -- the entire if statement by the sequence of else statements.
2260 if No
(Elsif_Parts
(N
)) then
2262 if No
(Else_Statements
(N
))
2263 or else Is_Empty_List
(Else_Statements
(N
))
2266 Make_Null_Statement
(Sloc
(N
)));
2269 Hed
:= Remove_Head
(Else_Statements
(N
));
2270 Insert_List_After
(N
, Else_Statements
(N
));
2276 -- If there are elsif statements, the first of them becomes
2277 -- the if/then section of the rebuilt if statement This is
2278 -- the case where we loop to reprocess this copied condition.
2281 Hed
:= Remove_Head
(Elsif_Parts
(N
));
2282 Insert_Actions
(N
, Condition_Actions
(Hed
));
2283 Set_Condition
(N
, Condition
(Hed
));
2284 Set_Then_Statements
(N
, Then_Statements
(Hed
));
2286 -- Hed might have been captured as the condition determining
2287 -- the current value for an entity. Now it is detached from
2288 -- the tree, so a Current_Value pointer in the condition might
2289 -- need to be updated.
2291 Check_Possible_Current_Value_Condition
(N
);
2293 if Is_Empty_List
(Elsif_Parts
(N
)) then
2294 Set_Elsif_Parts
(N
, No_List
);
2300 -- Loop through elsif parts, dealing with constant conditions and
2301 -- possible expression actions that are present.
2303 if Present
(Elsif_Parts
(N
)) then
2304 E
:= First
(Elsif_Parts
(N
));
2305 while Present
(E
) loop
2306 Adjust_Condition
(Condition
(E
));
2308 -- If there are condition actions, then we rewrite the if
2309 -- statement as indicated above. We also do the same rewrite
2310 -- if the condition is True or False. The further processing
2311 -- of this constant condition is then done by the recursive
2312 -- call to expand the newly created if statement
2314 if Present
(Condition_Actions
(E
))
2315 or else Compile_Time_Known_Value
(Condition
(E
))
2317 -- Note this is not an implicit if statement, since it is
2318 -- part of an explicit if statement in the source (or of an
2319 -- implicit if statement that has already been tested).
2322 Make_If_Statement
(Sloc
(E
),
2323 Condition
=> Condition
(E
),
2324 Then_Statements
=> Then_Statements
(E
),
2325 Elsif_Parts
=> No_List
,
2326 Else_Statements
=> Else_Statements
(N
));
2328 -- Elsif parts for new if come from remaining elsif's of parent
2330 while Present
(Next
(E
)) loop
2331 if No
(Elsif_Parts
(New_If
)) then
2332 Set_Elsif_Parts
(New_If
, New_List
);
2335 Append
(Remove_Next
(E
), Elsif_Parts
(New_If
));
2338 Set_Else_Statements
(N
, New_List
(New_If
));
2340 if Present
(Condition_Actions
(E
)) then
2341 Insert_List_Before
(New_If
, Condition_Actions
(E
));
2346 if Is_Empty_List
(Elsif_Parts
(N
)) then
2347 Set_Elsif_Parts
(N
, No_List
);
2353 -- No special processing for that elsif part, move to next
2361 -- Some more optimizations applicable if we still have an IF statement
2363 if Nkind
(N
) /= N_If_Statement
then
2367 -- Another optimization, special cases that can be simplified
2369 -- if expression then
2375 -- can be changed to:
2377 -- return expression;
2381 -- if expression then
2387 -- can be changed to:
2389 -- return not (expression);
2391 if Nkind
(N
) = N_If_Statement
2392 and then No
(Elsif_Parts
(N
))
2393 and then Present
(Else_Statements
(N
))
2394 and then List_Length
(Then_Statements
(N
)) = 1
2395 and then List_Length
(Else_Statements
(N
)) = 1
2398 Then_Stm
: constant Node_Id
:= First
(Then_Statements
(N
));
2399 Else_Stm
: constant Node_Id
:= First
(Else_Statements
(N
));
2402 if Nkind
(Then_Stm
) = N_Return_Statement
2404 Nkind
(Else_Stm
) = N_Return_Statement
2407 Then_Expr
: constant Node_Id
:= Expression
(Then_Stm
);
2408 Else_Expr
: constant Node_Id
:= Expression
(Else_Stm
);
2411 if Nkind
(Then_Expr
) = N_Identifier
2413 Nkind
(Else_Expr
) = N_Identifier
2415 if Entity
(Then_Expr
) = Standard_True
2416 and then Entity
(Else_Expr
) = Standard_False
2419 Make_Return_Statement
(Loc
,
2420 Expression
=> Relocate_Node
(Condition
(N
))));
2424 elsif Entity
(Then_Expr
) = Standard_False
2425 and then Entity
(Else_Expr
) = Standard_True
2428 Make_Return_Statement
(Loc
,
2431 Right_Opnd
=> Relocate_Node
(Condition
(N
)))));
2440 end Expand_N_If_Statement
;
2442 -----------------------------
2443 -- Expand_N_Loop_Statement --
2444 -----------------------------
2446 -- 1. Deal with while condition for C/Fortran boolean
2447 -- 2. Deal with loops with a non-standard enumeration type range
2448 -- 3. Deal with while loops where Condition_Actions is set
2449 -- 4. Insert polling call if required
2451 procedure Expand_N_Loop_Statement
(N
: Node_Id
) is
2452 Loc
: constant Source_Ptr
:= Sloc
(N
);
2453 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
2456 if Present
(Isc
) then
2457 Adjust_Condition
(Condition
(Isc
));
2460 if Is_Non_Empty_List
(Statements
(N
)) then
2461 Generate_Poll_Call
(First
(Statements
(N
)));
2468 -- Handle the case where we have a for loop with the range type being
2469 -- an enumeration type with non-standard representation. In this case
2472 -- for x in [reverse] a .. b loop
2478 -- for xP in [reverse] integer
2479 -- range etype'Pos (a) .. etype'Pos (b) loop
2481 -- x : constant etype := Pos_To_Rep (xP);
2487 if Present
(Loop_Parameter_Specification
(Isc
)) then
2489 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Isc
);
2490 Loop_Id
: constant Entity_Id
:= Defining_Identifier
(LPS
);
2491 Ltype
: constant Entity_Id
:= Etype
(Loop_Id
);
2492 Btype
: constant Entity_Id
:= Base_Type
(Ltype
);
2497 if not Is_Enumeration_Type
(Btype
)
2498 or else No
(Enum_Pos_To_Rep
(Btype
))
2504 Make_Defining_Identifier
(Loc
,
2505 Chars
=> New_External_Name
(Chars
(Loop_Id
), 'P'));
2507 -- If the type has a contiguous representation, successive
2508 -- values can be generated as offsets from the first literal.
2510 if Has_Contiguous_Rep
(Btype
) then
2512 Unchecked_Convert_To
(Btype
,
2515 Make_Integer_Literal
(Loc
,
2516 Enumeration_Rep
(First_Literal
(Btype
))),
2517 Right_Opnd
=> New_Reference_To
(New_Id
, Loc
)));
2519 -- Use the constructed array Enum_Pos_To_Rep
2522 Make_Indexed_Component
(Loc
,
2523 Prefix
=> New_Reference_To
(Enum_Pos_To_Rep
(Btype
), Loc
),
2524 Expressions
=> New_List
(New_Reference_To
(New_Id
, Loc
)));
2528 Make_Loop_Statement
(Loc
,
2529 Identifier
=> Identifier
(N
),
2532 Make_Iteration_Scheme
(Loc
,
2533 Loop_Parameter_Specification
=>
2534 Make_Loop_Parameter_Specification
(Loc
,
2535 Defining_Identifier
=> New_Id
,
2536 Reverse_Present
=> Reverse_Present
(LPS
),
2538 Discrete_Subtype_Definition
=>
2539 Make_Subtype_Indication
(Loc
,
2542 New_Reference_To
(Standard_Natural
, Loc
),
2545 Make_Range_Constraint
(Loc
,
2550 Make_Attribute_Reference
(Loc
,
2552 New_Reference_To
(Btype
, Loc
),
2554 Attribute_Name
=> Name_Pos
,
2556 Expressions
=> New_List
(
2558 (Type_Low_Bound
(Ltype
)))),
2561 Make_Attribute_Reference
(Loc
,
2563 New_Reference_To
(Btype
, Loc
),
2565 Attribute_Name
=> Name_Pos
,
2567 Expressions
=> New_List
(
2569 (Type_High_Bound
(Ltype
))))))))),
2571 Statements
=> New_List
(
2572 Make_Block_Statement
(Loc
,
2573 Declarations
=> New_List
(
2574 Make_Object_Declaration
(Loc
,
2575 Defining_Identifier
=> Loop_Id
,
2576 Constant_Present
=> True,
2577 Object_Definition
=> New_Reference_To
(Ltype
, Loc
),
2578 Expression
=> Expr
)),
2580 Handled_Statement_Sequence
=>
2581 Make_Handled_Sequence_Of_Statements
(Loc
,
2582 Statements
=> Statements
(N
)))),
2584 End_Label
=> End_Label
(N
)));
2588 -- Second case, if we have a while loop with Condition_Actions set,
2589 -- then we change it into a plain loop:
2598 -- <<condition actions>>
2604 and then Present
(Condition_Actions
(Isc
))
2611 Make_Exit_Statement
(Sloc
(Condition
(Isc
)),
2613 Make_Op_Not
(Sloc
(Condition
(Isc
)),
2614 Right_Opnd
=> Condition
(Isc
)));
2616 Prepend
(ES
, Statements
(N
));
2617 Insert_List_Before
(ES
, Condition_Actions
(Isc
));
2619 -- This is not an implicit loop, since it is generated in
2620 -- response to the loop statement being processed. If this
2621 -- is itself implicit, the restriction has already been
2622 -- checked. If not, it is an explicit loop.
2625 Make_Loop_Statement
(Sloc
(N
),
2626 Identifier
=> Identifier
(N
),
2627 Statements
=> Statements
(N
),
2628 End_Label
=> End_Label
(N
)));
2633 end Expand_N_Loop_Statement
;
2635 -------------------------------
2636 -- Expand_N_Return_Statement --
2637 -------------------------------
2639 procedure Expand_N_Return_Statement
(N
: Node_Id
) is
2640 Loc
: constant Source_Ptr
:= Sloc
(N
);
2641 Exp
: constant Node_Id
:= Expression
(N
);
2645 Scope_Id
: Entity_Id
;
2649 Goto_Stat
: Node_Id
;
2652 Return_Type
: Entity_Id
;
2653 Result_Exp
: Node_Id
;
2654 Result_Id
: Entity_Id
;
2655 Result_Obj
: Node_Id
;
2658 -- Case where returned expression is present
2660 if Present
(Exp
) then
2662 -- Always normalize C/Fortran boolean result. This is not always
2663 -- necessary, but it seems a good idea to minimize the passing
2664 -- around of non-normalized values, and in any case this handles
2665 -- the processing of barrier functions for protected types, which
2666 -- turn the condition into a return statement.
2668 Exptyp
:= Etype
(Exp
);
2670 if Is_Boolean_Type
(Exptyp
)
2671 and then Nonzero_Is_True
(Exptyp
)
2673 Adjust_Condition
(Exp
);
2674 Adjust_Result_Type
(Exp
, Exptyp
);
2677 -- Do validity check if enabled for returns
2679 if Validity_Checks_On
2680 and then Validity_Check_Returns
2686 -- Find relevant enclosing scope from which return is returning
2688 Cur_Idx
:= Scope_Stack
.Last
;
2690 Scope_Id
:= Scope_Stack
.Table
(Cur_Idx
).Entity
;
2692 if Ekind
(Scope_Id
) /= E_Block
2693 and then Ekind
(Scope_Id
) /= E_Loop
2698 Cur_Idx
:= Cur_Idx
- 1;
2699 pragma Assert
(Cur_Idx
>= 0);
2704 Kind
:= Ekind
(Scope_Id
);
2706 -- If it is a return from procedures do no extra steps
2708 if Kind
= E_Procedure
or else Kind
= E_Generic_Procedure
then
2712 pragma Assert
(Is_Entry
(Scope_Id
));
2714 -- Look at the enclosing block to see whether the return is from
2715 -- an accept statement or an entry body.
2717 for J
in reverse 0 .. Cur_Idx
loop
2718 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
2719 exit when Is_Concurrent_Type
(Scope_Id
);
2722 -- If it is a return from accept statement it should be expanded
2723 -- as a call to RTS Complete_Rendezvous and a goto to the end of
2726 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
2727 -- Expand_N_Accept_Alternative in exp_ch9.adb)
2729 if Is_Task_Type
(Scope_Id
) then
2731 Call
:= (Make_Procedure_Call_Statement
(Loc
,
2732 Name
=> New_Reference_To
2733 (RTE
(RE_Complete_Rendezvous
), Loc
)));
2734 Insert_Before
(N
, Call
);
2735 -- why not insert actions here???
2738 Acc_Stat
:= Parent
(N
);
2739 while Nkind
(Acc_Stat
) /= N_Accept_Statement
loop
2740 Acc_Stat
:= Parent
(Acc_Stat
);
2743 Lab_Node
:= Last
(Statements
2744 (Handled_Statement_Sequence
(Acc_Stat
)));
2746 Goto_Stat
:= Make_Goto_Statement
(Loc
,
2747 Name
=> New_Occurrence_Of
2748 (Entity
(Identifier
(Lab_Node
)), Loc
));
2750 Set_Analyzed
(Goto_Stat
);
2752 Rewrite
(N
, Goto_Stat
);
2755 -- If it is a return from an entry body, put a Complete_Entry_Body
2756 -- call in front of the return.
2758 elsif Is_Protected_Type
(Scope_Id
) then
2761 Make_Procedure_Call_Statement
(Loc
,
2762 Name
=> New_Reference_To
2763 (RTE
(RE_Complete_Entry_Body
), Loc
),
2764 Parameter_Associations
=> New_List
2765 (Make_Attribute_Reference
(Loc
,
2769 (Corresponding_Body
(Parent
(Scope_Id
))),
2771 Attribute_Name
=> Name_Unchecked_Access
)));
2773 Insert_Before
(N
, Call
);
2782 Return_Type
:= Etype
(Scope_Id
);
2783 Utyp
:= Underlying_Type
(Return_Type
);
2785 -- Check the result expression of a scalar function against
2786 -- the subtype of the function by inserting a conversion.
2787 -- This conversion must eventually be performed for other
2788 -- classes of types, but for now it's only done for scalars.
2791 if Is_Scalar_Type
(T
) then
2792 Rewrite
(Exp
, Convert_To
(Return_Type
, Exp
));
2796 -- Deal with returning variable length objects and controlled types
2798 -- Nothing to do if we are returning by reference, or this is not
2799 -- a type that requires special processing (indicated by the fact
2800 -- that it requires a cleanup scope for the secondary stack case).
2802 if Is_Return_By_Reference_Type
(T
) then
2805 elsif not Requires_Transient_Scope
(Return_Type
) then
2807 -- Mutable records with no variable length components are not
2808 -- returned on the sec-stack so we need to make sure that the
2809 -- backend will only copy back the size of the actual value and not
2810 -- the maximum size. We create an actual subtype for this purpose
2813 Ubt
: constant Entity_Id
:= Underlying_Type
(Base_Type
(T
));
2817 if Has_Discriminants
(Ubt
)
2818 and then not Is_Constrained
(Ubt
)
2819 and then not Has_Unchecked_Union
(Ubt
)
2821 Decl
:= Build_Actual_Subtype
(Ubt
, Exp
);
2822 Ent
:= Defining_Identifier
(Decl
);
2823 Insert_Action
(Exp
, Decl
);
2824 Rewrite
(Exp
, Unchecked_Convert_To
(Ent
, Exp
));
2828 -- Case of secondary stack not used
2830 elsif Function_Returns_With_DSP
(Scope_Id
) then
2832 -- Here what we need to do is to always return by reference, since
2833 -- we will return with the stack pointer depressed. We may need to
2834 -- do a copy to a local temporary before doing this return.
2836 No_Secondary_Stack_Case
: declare
2837 Local_Copy_Required
: Boolean := False;
2838 -- Set to True if a local copy is required
2840 Copy_Ent
: Entity_Id
;
2841 -- Used for the target entity if a copy is required
2844 -- Declaration used to create copy if needed
2846 procedure Test_Copy_Required
(Expr
: Node_Id
);
2847 -- Determines if Expr represents a return value for which a
2848 -- copy is required. More specifically, a copy is not required
2849 -- if Expr represents an object or component of an object that
2850 -- is either in the local subprogram frame, or is constant.
2851 -- If a copy is required, then Local_Copy_Required is set True.
2853 ------------------------
2854 -- Test_Copy_Required --
2855 ------------------------
2857 procedure Test_Copy_Required
(Expr
: Node_Id
) is
2861 -- If component, test prefix (object containing component)
2863 if Nkind
(Expr
) = N_Indexed_Component
2865 Nkind
(Expr
) = N_Selected_Component
2867 Test_Copy_Required
(Prefix
(Expr
));
2870 -- See if we have an entity name
2872 elsif Is_Entity_Name
(Expr
) then
2873 Ent
:= Entity
(Expr
);
2875 -- Constant entity is always OK, no copy required
2877 if Ekind
(Ent
) = E_Constant
then
2880 -- No copy required for local variable
2882 elsif Ekind
(Ent
) = E_Variable
2883 and then Scope
(Ent
) = Current_Subprogram
2889 -- All other cases require a copy
2891 Local_Copy_Required
:= True;
2892 end Test_Copy_Required
;
2894 -- Start of processing for No_Secondary_Stack_Case
2897 -- No copy needed if result is from a function call.
2898 -- In this case the result is already being returned by
2899 -- reference with the stack pointer depressed.
2901 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2902 -- the copy for array types if the constrained status of the
2903 -- target type is different from that of the expression.
2905 if Requires_Transient_Scope
(T
)
2907 (not Is_Array_Type
(T
)
2908 or else Is_Constrained
(T
) = Is_Constrained
(Return_Type
)
2909 or else Controlled_Type
(T
))
2910 and then Nkind
(Exp
) = N_Function_Call
2914 -- We always need a local copy for a controlled type, since
2915 -- we are required to finalize the local value before return.
2916 -- The copy will automatically include the required finalize.
2917 -- Moreover, gigi cannot make this copy, since we need special
2918 -- processing to ensure proper behavior for finalization.
2920 -- Note: the reason we are returning with a depressed stack
2921 -- pointer in the controlled case (even if the type involved
2922 -- is constrained) is that we must make a local copy to deal
2923 -- properly with the requirement that the local result be
2926 elsif Controlled_Type
(Utyp
) then
2928 Make_Defining_Identifier
(Loc
,
2929 Chars
=> New_Internal_Name
('R'));
2931 -- Build declaration to do the copy, and insert it, setting
2932 -- Assignment_OK, because we may be copying a limited type.
2933 -- In addition we set the special flag to inhibit finalize
2934 -- attachment if this is a controlled type (since this attach
2935 -- must be done by the caller, otherwise if we attach it here
2936 -- we will finalize the returned result prematurely).
2939 Make_Object_Declaration
(Loc
,
2940 Defining_Identifier
=> Copy_Ent
,
2941 Object_Definition
=> New_Occurrence_Of
(Return_Type
, Loc
),
2942 Expression
=> Relocate_Node
(Exp
));
2944 Set_Assignment_OK
(Decl
);
2945 Set_Delay_Finalize_Attach
(Decl
);
2946 Insert_Action
(N
, Decl
);
2948 -- Now the actual return uses the copied value
2950 Rewrite
(Exp
, New_Occurrence_Of
(Copy_Ent
, Loc
));
2951 Analyze_And_Resolve
(Exp
, Return_Type
);
2953 -- Since we have made the copy, gigi does not have to, so
2954 -- we set the By_Ref flag to prevent another copy being made.
2958 -- Non-controlled cases
2961 Test_Copy_Required
(Exp
);
2963 -- If a local copy is required, then gigi will make the
2964 -- copy, otherwise, we can return the result directly,
2965 -- so set By_Ref to suppress the gigi copy.
2967 if not Local_Copy_Required
then
2971 end No_Secondary_Stack_Case
;
2973 -- Here if secondary stack is used
2976 -- Make sure that no surrounding block will reclaim the
2977 -- secondary-stack on which we are going to put the result.
2978 -- Not only may this introduce secondary stack leaks but worse,
2979 -- if the reclamation is done too early, then the result we are
2980 -- returning may get clobbered. See example in 7417-003.
2983 S
: Entity_Id
:= Current_Scope
;
2986 while Ekind
(S
) = E_Block
or else Ekind
(S
) = E_Loop
loop
2987 Set_Sec_Stack_Needed_For_Return
(S
, True);
2988 S
:= Enclosing_Dynamic_Scope
(S
);
2992 -- Optimize the case where the result is a function call. In this
2993 -- case either the result is already on the secondary stack, or is
2994 -- already being returned with the stack pointer depressed and no
2995 -- further processing is required except to set the By_Ref flag to
2996 -- ensure that gigi does not attempt an extra unnecessary copy.
2997 -- (actually not just unnecessary but harmfully wrong in the case
2998 -- of a controlled type, where gigi does not know how to do a copy).
2999 -- To make up for a gcc 2.8.1 deficiency (???), we perform
3000 -- the copy for array types if the constrained status of the
3001 -- target type is different from that of the expression.
3003 if Requires_Transient_Scope
(T
)
3005 (not Is_Array_Type
(T
)
3006 or else Is_Constrained
(T
) = Is_Constrained
(Return_Type
)
3007 or else Controlled_Type
(T
))
3008 and then Nkind
(Exp
) = N_Function_Call
3012 -- Remove side effects from the expression now so that
3013 -- other part of the expander do not have to reanalyze
3014 -- this node without this optimization
3016 Rewrite
(Exp
, Duplicate_Subexpr_No_Checks
(Exp
));
3018 -- For controlled types, do the allocation on the sec-stack
3019 -- manually in order to call adjust at the right time
3020 -- type Anon1 is access Return_Type;
3021 -- for Anon1'Storage_pool use ss_pool;
3022 -- Anon2 : anon1 := new Return_Type'(expr);
3023 -- return Anon2.all;
3025 elsif Controlled_Type
(Utyp
) then
3027 Loc
: constant Source_Ptr
:= Sloc
(N
);
3028 Temp
: constant Entity_Id
:=
3029 Make_Defining_Identifier
(Loc
,
3030 Chars
=> New_Internal_Name
('R'));
3031 Acc_Typ
: constant Entity_Id
:=
3032 Make_Defining_Identifier
(Loc
,
3033 Chars
=> New_Internal_Name
('A'));
3034 Alloc_Node
: Node_Id
;
3037 Set_Ekind
(Acc_Typ
, E_Access_Type
);
3039 Set_Associated_Storage_Pool
(Acc_Typ
, RTE
(RE_SS_Pool
));
3042 Make_Allocator
(Loc
,
3044 Make_Qualified_Expression
(Loc
,
3045 Subtype_Mark
=> New_Reference_To
(Etype
(Exp
), Loc
),
3046 Expression
=> Relocate_Node
(Exp
)));
3048 Insert_List_Before_And_Analyze
(N
, New_List
(
3049 Make_Full_Type_Declaration
(Loc
,
3050 Defining_Identifier
=> Acc_Typ
,
3052 Make_Access_To_Object_Definition
(Loc
,
3053 Subtype_Indication
=>
3054 New_Reference_To
(Return_Type
, Loc
))),
3056 Make_Object_Declaration
(Loc
,
3057 Defining_Identifier
=> Temp
,
3058 Object_Definition
=> New_Reference_To
(Acc_Typ
, Loc
),
3059 Expression
=> Alloc_Node
)));
3062 Make_Explicit_Dereference
(Loc
,
3063 Prefix
=> New_Reference_To
(Temp
, Loc
)));
3065 Analyze_And_Resolve
(Exp
, Return_Type
);
3068 -- Otherwise use the gigi mechanism to allocate result on the
3072 Set_Storage_Pool
(N
, RTE
(RE_SS_Pool
));
3074 -- If we are generating code for the Java VM do not use
3075 -- SS_Allocate since everything is heap-allocated anyway.
3078 Set_Procedure_To_Call
(N
, RTE
(RE_SS_Allocate
));
3083 -- Implement the rules of 6.5(8-10), which require a tag check in
3084 -- the case of a limited tagged return type, and tag reassignment
3085 -- for nonlimited tagged results. These actions are needed when
3086 -- the return type is a specific tagged type and the result
3087 -- expression is a conversion or a formal parameter, because in
3088 -- that case the tag of the expression might differ from the tag
3089 -- of the specific result type.
3091 if Is_Tagged_Type
(Utyp
)
3092 and then not Is_Class_Wide_Type
(Utyp
)
3093 and then (Nkind
(Exp
) = N_Type_Conversion
3094 or else Nkind
(Exp
) = N_Unchecked_Type_Conversion
3095 or else (Is_Entity_Name
(Exp
)
3096 and then Ekind
(Entity
(Exp
)) in Formal_Kind
))
3098 -- When the return type is limited, perform a check that the
3099 -- tag of the result is the same as the tag of the return type.
3101 if Is_Limited_Type
(Return_Type
) then
3103 Make_Raise_Constraint_Error
(Loc
,
3107 Make_Selected_Component
(Loc
,
3108 Prefix
=> Duplicate_Subexpr
(Exp
),
3110 New_Reference_To
(First_Tag_Component
(Utyp
), Loc
)),
3112 Unchecked_Convert_To
(RTE
(RE_Tag
),
3115 (Access_Disp_Table
(Base_Type
(Utyp
)))),
3117 Reason
=> CE_Tag_Check_Failed
));
3119 -- If the result type is a specific nonlimited tagged type,
3120 -- then we have to ensure that the tag of the result is that
3121 -- of the result type. This is handled by making a copy of the
3122 -- expression in the case where it might have a different tag,
3123 -- namely when the expression is a conversion or a formal
3124 -- parameter. We create a new object of the result type and
3125 -- initialize it from the expression, which will implicitly
3126 -- force the tag to be set appropriately.
3130 Make_Defining_Identifier
(Loc
, New_Internal_Name
('R'));
3131 Result_Exp
:= New_Reference_To
(Result_Id
, Loc
);
3134 Make_Object_Declaration
(Loc
,
3135 Defining_Identifier
=> Result_Id
,
3136 Object_Definition
=> New_Reference_To
(Return_Type
, Loc
),
3137 Constant_Present
=> True,
3138 Expression
=> Relocate_Node
(Exp
));
3140 Set_Assignment_OK
(Result_Obj
);
3141 Insert_Action
(Exp
, Result_Obj
);
3143 Rewrite
(Exp
, Result_Exp
);
3144 Analyze_And_Resolve
(Exp
, Return_Type
);
3147 -- Ada 2005 (AI-344): If the result type is class-wide, then insert
3148 -- a check that the level of the return expression's underlying type
3149 -- is not deeper than the level of the master enclosing the function.
3150 -- Always generate the check when the type of the return expression
3151 -- is class-wide, when it's a type conversion, or when it's a formal
3152 -- parameter. Otherwise, suppress the check in the case where the
3153 -- return expression has a specific type whose level is known not to
3154 -- be statically deeper than the function's result type.
3156 elsif Ada_Version
>= Ada_05
3157 and then Is_Class_Wide_Type
(Return_Type
)
3158 and then not Scope_Suppress
(Accessibility_Check
)
3160 (Is_Class_Wide_Type
(Etype
(Exp
))
3161 or else Nkind
(Exp
) = N_Type_Conversion
3162 or else Nkind
(Exp
) = N_Unchecked_Type_Conversion
3163 or else (Is_Entity_Name
(Exp
)
3164 and then Ekind
(Entity
(Exp
)) in Formal_Kind
)
3165 or else Scope_Depth
(Enclosing_Dynamic_Scope
(Etype
(Exp
))) >
3166 Scope_Depth
(Enclosing_Dynamic_Scope
(Scope_Id
)))
3169 Make_Raise_Program_Error
(Loc
,
3173 Make_Function_Call
(Loc
,
3176 (RTE
(RE_Get_Access_Level
), Loc
),
3177 Parameter_Associations
=>
3178 New_List
(Make_Attribute_Reference
(Loc
,
3180 Duplicate_Subexpr
(Exp
),
3184 Make_Integer_Literal
(Loc
,
3185 Scope_Depth
(Enclosing_Dynamic_Scope
(Scope_Id
)))),
3186 Reason
=> PE_Accessibility_Check_Failed
));
3190 when RE_Not_Available
=>
3192 end Expand_N_Return_Statement
;
3194 ------------------------------
3195 -- Make_Tag_Ctrl_Assignment --
3196 ------------------------------
3198 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
is
3199 Loc
: constant Source_Ptr
:= Sloc
(N
);
3200 L
: constant Node_Id
:= Name
(N
);
3201 T
: constant Entity_Id
:= Underlying_Type
(Etype
(L
));
3203 Ctrl_Act
: constant Boolean := Controlled_Type
(T
)
3204 and then not No_Ctrl_Actions
(N
);
3206 Save_Tag
: constant Boolean := Is_Tagged_Type
(T
)
3207 and then not No_Ctrl_Actions
(N
)
3208 and then not Java_VM
;
3209 -- Tags are not saved and restored when Java_VM because JVM tags
3210 -- are represented implicitly in objects.
3213 Tag_Tmp
: Entity_Id
;
3218 -- Finalize the target of the assignment when controlled.
3219 -- We have two exceptions here:
3221 -- 1. If we are in an init proc since it is an initialization
3222 -- more than an assignment
3224 -- 2. If the left-hand side is a temporary that was not initialized
3225 -- (or the parent part of a temporary since it is the case in
3226 -- extension aggregates). Such a temporary does not come from
3227 -- source. We must examine the original node for the prefix, because
3228 -- it may be a component of an entry formal, in which case it has
3229 -- been rewritten and does not appear to come from source either.
3231 -- Case of init proc
3233 if not Ctrl_Act
then
3236 -- The left hand side is an uninitialized temporary
3238 elsif Nkind
(L
) = N_Type_Conversion
3239 and then Is_Entity_Name
(Expression
(L
))
3240 and then No_Initialization
(Parent
(Entity
(Expression
(L
))))
3244 Append_List_To
(Res
,
3246 Ref
=> Duplicate_Subexpr_No_Checks
(L
),
3248 With_Detach
=> New_Reference_To
(Standard_False
, Loc
)));
3251 -- Save the Tag in a local variable Tag_Tmp
3255 Make_Defining_Identifier
(Loc
, New_Internal_Name
('A'));
3258 Make_Object_Declaration
(Loc
,
3259 Defining_Identifier
=> Tag_Tmp
,
3260 Object_Definition
=> New_Reference_To
(RTE
(RE_Tag
), Loc
),
3262 Make_Selected_Component
(Loc
,
3263 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
3264 Selector_Name
=> New_Reference_To
(First_Tag_Component
(T
),
3267 -- Otherwise Tag_Tmp not used
3273 -- Processing for controlled types and types with controlled components
3275 -- Variables of such types contain pointers used to chain them in
3276 -- finalization lists, in addition to user data. These pointers are
3277 -- specific to each object of the type, not to the value being assigned.
3278 -- Thus they need to be left intact during the assignment. We achieve
3279 -- this by constructing a Storage_Array subtype, and by overlaying
3280 -- objects of this type on the source and target of the assignment.
3281 -- The assignment is then rewritten to assignments of slices of these
3282 -- arrays, copying the user data, and leaving the pointers untouched.
3285 Controlled_Actions
: declare
3287 -- A reference to the Prev component of the record controller
3289 First_After_Root
: Node_Id
:= Empty
;
3290 -- Index of first byte to be copied (used to skip
3291 -- Root_Controlled in controlled objects).
3293 Last_Before_Hole
: Node_Id
:= Empty
;
3294 -- Index of last byte to be copied before outermost record
3297 Hole_Length
: Node_Id
:= Empty
;
3298 -- Length of record controller data (Prev and Next pointers)
3300 First_After_Hole
: Node_Id
:= Empty
;
3301 -- Index of first byte to be copied after outermost record
3304 Expr
, Source_Size
: Node_Id
;
3305 Source_Actual_Subtype
: Entity_Id
;
3306 -- Used for computation of the size of the data to be copied
3308 Range_Type
: Entity_Id
;
3309 Opaque_Type
: Entity_Id
;
3311 function Build_Slice
3314 Hi
: Node_Id
) return Node_Id
;
3315 -- Build and return a slice of an array of type S overlaid
3316 -- on object Rec, with bounds specified by Lo and Hi. If either
3317 -- bound is empty, a default of S'First (respectively S'Last)
3324 function Build_Slice
3327 Hi
: Node_Id
) return Node_Id
3332 Opaque
: constant Node_Id
:=
3333 Unchecked_Convert_To
(Opaque_Type
,
3334 Make_Attribute_Reference
(Loc
,
3336 Attribute_Name
=> Name_Address
));
3337 -- Access value designating an opaque storage array of
3338 -- type S overlaid on record Rec.
3341 -- Compute slice bounds using S'First (1) and S'Last
3342 -- as default values when not specified by the caller.
3345 Lo_Bound
:= Make_Integer_Literal
(Loc
, 1);
3351 Hi_Bound
:= Make_Attribute_Reference
(Loc
,
3352 Prefix
=> New_Occurrence_Of
(Range_Type
, Loc
),
3353 Attribute_Name
=> Name_Last
);
3358 return Make_Slice
(Loc
,
3361 Discrete_Range
=> Make_Range
(Loc
,
3362 Lo_Bound
, Hi_Bound
));
3365 -- Start of processing for Controlled_Actions
3368 -- Create a constrained subtype of Storage_Array whose size
3369 -- corresponds to the value being assigned.
3371 -- subtype G is Storage_Offset range
3372 -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit
3374 Expr
:= Duplicate_Subexpr_No_Checks
(Expression
(N
));
3376 if Nkind
(Expr
) = N_Qualified_Expression
then
3377 Expr
:= Expression
(Expr
);
3380 Source_Actual_Subtype
:= Etype
(Expr
);
3382 if Has_Discriminants
(Source_Actual_Subtype
)
3383 and then not Is_Constrained
(Source_Actual_Subtype
)
3386 Build_Actual_Subtype
(Source_Actual_Subtype
, Expr
));
3387 Source_Actual_Subtype
:= Defining_Identifier
(Last
(Res
));
3393 Make_Attribute_Reference
(Loc
,
3395 New_Occurrence_Of
(Source_Actual_Subtype
, Loc
),
3399 Make_Integer_Literal
(Loc
,
3400 System_Storage_Unit
- 1));
3402 Make_Op_Divide
(Loc
,
3403 Left_Opnd
=> Source_Size
,
3405 Make_Integer_Literal
(Loc
,
3406 Intval
=> System_Storage_Unit
));
3409 Make_Defining_Identifier
(Loc
,
3410 New_Internal_Name
('G'));
3413 Make_Subtype_Declaration
(Loc
,
3414 Defining_Identifier
=> Range_Type
,
3415 Subtype_Indication
=>
3416 Make_Subtype_Indication
(Loc
,
3418 New_Reference_To
(RTE
(RE_Storage_Offset
), Loc
),
3419 Constraint
=> Make_Range_Constraint
(Loc
,
3422 Low_Bound
=> Make_Integer_Literal
(Loc
, 1),
3423 High_Bound
=> Source_Size
)))));
3425 -- subtype S is Storage_Array (G)
3428 Make_Subtype_Declaration
(Loc
,
3429 Defining_Identifier
=>
3430 Make_Defining_Identifier
(Loc
,
3431 New_Internal_Name
('S')),
3432 Subtype_Indication
=>
3433 Make_Subtype_Indication
(Loc
,
3435 New_Reference_To
(RTE
(RE_Storage_Array
), Loc
),
3437 Make_Index_Or_Discriminant_Constraint
(Loc
,
3439 New_List
(New_Reference_To
(Range_Type
, Loc
))))));
3441 -- type A is access S
3444 Make_Defining_Identifier
(Loc
,
3445 Chars
=> New_Internal_Name
('A'));
3448 Make_Full_Type_Declaration
(Loc
,
3449 Defining_Identifier
=> Opaque_Type
,
3451 Make_Access_To_Object_Definition
(Loc
,
3452 Subtype_Indication
=>
3454 Defining_Identifier
(Last
(Res
)), Loc
))));
3456 -- Generate appropriate slice assignments
3458 First_After_Root
:= Make_Integer_Literal
(Loc
, 1);
3460 -- For the case of a controlled object, skip the
3461 -- Root_Controlled part.
3463 if Is_Controlled
(T
) then
3467 Make_Op_Divide
(Loc
,
3468 Make_Attribute_Reference
(Loc
,
3470 New_Occurrence_Of
(RTE
(RE_Root_Controlled
), Loc
),
3471 Attribute_Name
=> Name_Size
),
3472 Make_Integer_Literal
(Loc
, System_Storage_Unit
)));
3475 -- For the case of a record with controlled components, skip
3476 -- the Prev and Next components of the record controller.
3477 -- These components constitute a 'hole' in the middle of the
3478 -- data to be copied.
3480 if Has_Controlled_Component
(T
) then
3482 Make_Selected_Component
(Loc
,
3484 Make_Selected_Component
(Loc
,
3485 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
3487 New_Reference_To
(Controller_Component
(T
), Loc
)),
3488 Selector_Name
=> Make_Identifier
(Loc
, Name_Prev
));
3490 -- Last index before hole: determined by position of
3491 -- the _Controller.Prev component.
3494 Make_Defining_Identifier
(Loc
,
3495 New_Internal_Name
('L'));
3498 Make_Object_Declaration
(Loc
,
3499 Defining_Identifier
=> Last_Before_Hole
,
3500 Object_Definition
=> New_Occurrence_Of
(
3501 RTE
(RE_Storage_Offset
), Loc
),
3502 Constant_Present
=> True,
3503 Expression
=> Make_Op_Add
(Loc
,
3504 Make_Attribute_Reference
(Loc
,
3506 Attribute_Name
=> Name_Position
),
3507 Make_Attribute_Reference
(Loc
,
3508 Prefix
=> New_Copy_Tree
(Prefix
(Prev_Ref
)),
3509 Attribute_Name
=> Name_Position
))));
3511 -- Hole length: size of the Prev and Next components
3514 Make_Op_Multiply
(Loc
,
3515 Left_Opnd
=> Make_Integer_Literal
(Loc
, Uint_2
),
3517 Make_Op_Divide
(Loc
,
3519 Make_Attribute_Reference
(Loc
,
3520 Prefix
=> New_Copy_Tree
(Prev_Ref
),
3521 Attribute_Name
=> Name_Size
),
3523 Make_Integer_Literal
(Loc
,
3524 Intval
=> System_Storage_Unit
)));
3526 -- First index after hole
3529 Make_Defining_Identifier
(Loc
,
3530 New_Internal_Name
('F'));
3533 Make_Object_Declaration
(Loc
,
3534 Defining_Identifier
=> First_After_Hole
,
3535 Object_Definition
=> New_Occurrence_Of
(
3536 RTE
(RE_Storage_Offset
), Loc
),
3537 Constant_Present
=> True,
3543 New_Occurrence_Of
(Last_Before_Hole
, Loc
),
3544 Right_Opnd
=> Hole_Length
),
3545 Right_Opnd
=> Make_Integer_Literal
(Loc
, 1))));
3547 Last_Before_Hole
:= New_Occurrence_Of
(Last_Before_Hole
, Loc
);
3548 First_After_Hole
:= New_Occurrence_Of
(First_After_Hole
, Loc
);
3551 -- Assign the first slice (possibly skipping Root_Controlled,
3552 -- up to the beginning of the record controller if present,
3553 -- up to the end of the object if not).
3555 Append_To
(Res
, Make_Assignment_Statement
(Loc
,
3556 Name
=> Build_Slice
(
3557 Rec
=> Duplicate_Subexpr_No_Checks
(L
),
3558 Lo
=> First_After_Root
,
3559 Hi
=> Last_Before_Hole
),
3561 Expression
=> Build_Slice
(
3562 Rec
=> Expression
(N
),
3563 Lo
=> First_After_Root
,
3564 Hi
=> New_Copy_Tree
(Last_Before_Hole
))));
3566 if Present
(First_After_Hole
) then
3568 -- If a record controller is present, copy the second slice,
3569 -- from right after the _Controller.Next component up to the
3570 -- end of the object.
3572 Append_To
(Res
, Make_Assignment_Statement
(Loc
,
3573 Name
=> Build_Slice
(
3574 Rec
=> Duplicate_Subexpr_No_Checks
(L
),
3575 Lo
=> First_After_Hole
,
3577 Expression
=> Build_Slice
(
3578 Rec
=> Duplicate_Subexpr_No_Checks
(Expression
(N
)),
3579 Lo
=> New_Copy_Tree
(First_After_Hole
),
3582 end Controlled_Actions
;
3585 Append_To
(Res
, Relocate_Node
(N
));
3592 Make_Assignment_Statement
(Loc
,
3594 Make_Selected_Component
(Loc
,
3595 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
3596 Selector_Name
=> New_Reference_To
(First_Tag_Component
(T
),
3598 Expression
=> New_Reference_To
(Tag_Tmp
, Loc
)));
3601 -- Adjust the target after the assignment when controlled (not in the
3602 -- init proc since it is an initialization more than an assignment).
3605 Append_List_To
(Res
,
3607 Ref
=> Duplicate_Subexpr_Move_Checks
(L
),
3609 Flist_Ref
=> New_Reference_To
(RTE
(RE_Global_Final_List
), Loc
),
3610 With_Attach
=> Make_Integer_Literal
(Loc
, 0)));
3616 -- Could use comment here ???
3618 when RE_Not_Available
=>
3620 end Make_Tag_Ctrl_Assignment
;
3622 ------------------------------------
3623 -- Possible_Bit_Aligned_Component --
3624 ------------------------------------
3626 function Possible_Bit_Aligned_Component
(N
: Node_Id
) return Boolean is
3630 -- Case of indexed component
3632 when N_Indexed_Component
=>
3634 P
: constant Node_Id
:= Prefix
(N
);
3635 Ptyp
: constant Entity_Id
:= Etype
(P
);
3638 -- If we know the component size and it is less than 64, then
3639 -- we are definitely OK. The back end always does assignment
3640 -- of misaligned small objects correctly.
3642 if Known_Static_Component_Size
(Ptyp
)
3643 and then Component_Size
(Ptyp
) <= 64
3647 -- Otherwise, we need to test the prefix, to see if we are
3648 -- indexing from a possibly unaligned component.
3651 return Possible_Bit_Aligned_Component
(P
);
3655 -- Case of selected component
3657 when N_Selected_Component
=>
3659 P
: constant Node_Id
:= Prefix
(N
);
3660 Comp
: constant Entity_Id
:= Entity
(Selector_Name
(N
));
3663 -- If there is no component clause, then we are in the clear
3664 -- since the back end will never misalign a large component
3665 -- unless it is forced to do so. In the clear means we need
3666 -- only the recursive test on the prefix.
3668 if Component_May_Be_Bit_Aligned
(Comp
) then
3671 return Possible_Bit_Aligned_Component
(P
);
3675 -- If we have neither a record nor array component, it means that
3676 -- we have fallen off the top testing prefixes recursively, and
3677 -- we now have a stand alone object, where we don't have a problem
3683 end Possible_Bit_Aligned_Component
;