1 -----------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2002, 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, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, 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 Exp_Aggr
; use Exp_Aggr
;
31 with Exp_Ch7
; use Exp_Ch7
;
32 with Exp_Ch11
; use Exp_Ch11
;
33 with Exp_Dbug
; use Exp_Dbug
;
34 with Exp_Pakd
; use Exp_Pakd
;
35 with Exp_Util
; use Exp_Util
;
36 with Hostparm
; use Hostparm
;
37 with Nlists
; use Nlists
;
38 with Nmake
; use Nmake
;
40 with Restrict
; use Restrict
;
41 with Rtsfind
; use Rtsfind
;
42 with Sinfo
; use Sinfo
;
44 with Sem_Ch8
; use Sem_Ch8
;
45 with Sem_Ch13
; use Sem_Ch13
;
46 with Sem_Eval
; use Sem_Eval
;
47 with Sem_Res
; use Sem_Res
;
48 with Sem_Util
; use Sem_Util
;
49 with Snames
; use Snames
;
50 with Stand
; use Stand
;
51 with Tbuild
; use Tbuild
;
52 with Ttypes
; use Ttypes
;
53 with Uintp
; use Uintp
;
54 with Validsw
; use Validsw
;
56 package body Exp_Ch5
is
58 function Change_Of_Representation
(N
: Node_Id
) return Boolean;
59 -- Determine if the right hand side of the assignment N is a type
60 -- conversion which requires a change of representation. Called
61 -- only for the array and record cases.
63 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
);
64 -- N is an assignment which assigns an array value. This routine process
65 -- the various special cases and checks required for such assignments,
66 -- including change of representation. Rhs is normally simply the right
67 -- hand side of the assignment, except that if the right hand side is
68 -- a type conversion or a qualified expression, then the Rhs is the
69 -- actual expression inside any such type conversions or qualifications.
71 function Expand_Assign_Array_Loop
80 -- N is an assignment statement which assigns an array value. This routine
81 -- expands the assignment into a loop (or nested loops for the case of a
82 -- multi-dimensional array) to do the assignment component by component.
83 -- Larray and Rarray are the entities of the actual arrays on the left
84 -- hand and right hand sides. L_Type and R_Type are the types of these
85 -- arrays (which may not be the same, due to either sliding, or to a
86 -- change of representation case). Ndim is the number of dimensions and
87 -- the parameter Rev indicates if the loops run normally (Rev = False),
88 -- or reversed (Rev = True). The value returned is the constructed
89 -- loop statement. Auxiliary declarations are inserted before node N
90 -- using the standard Insert_Actions mechanism.
92 procedure Expand_Assign_Record
(N
: Node_Id
);
93 -- N is an assignment of a non-tagged record value. This routine handles
94 -- the special cases and checks required for such assignments, including
95 -- change of representation.
97 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
;
98 -- Generate the necessary code for controlled and Tagged assignment,
99 -- that is to say, finalization of the target before, adjustement of
100 -- the target after and save and restore of the tag and finalization
101 -- pointers which are not 'part of the value' and must not be changed
102 -- upon assignment. N is the original Assignment node.
104 ------------------------------
105 -- Change_Of_Representation --
106 ------------------------------
108 function Change_Of_Representation
(N
: Node_Id
) return Boolean is
109 Rhs
: constant Node_Id
:= Expression
(N
);
113 Nkind
(Rhs
) = N_Type_Conversion
115 not Same_Representation
(Etype
(Rhs
), Etype
(Expression
(Rhs
)));
116 end Change_Of_Representation
;
118 -------------------------
119 -- Expand_Assign_Array --
120 -------------------------
122 -- There are two issues here. First, do we let Gigi do a block move, or
123 -- do we expand out into a loop? Second, we need to set the two flags
124 -- Forwards_OK and Backwards_OK which show whether the block move (or
125 -- corresponding loops) can be legitimately done in a forwards (low to
126 -- high) or backwards (high to low) manner.
128 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
) is
129 Loc
: constant Source_Ptr
:= Sloc
(N
);
131 Lhs
: constant Node_Id
:= Name
(N
);
133 Act_Lhs
: constant Node_Id
:= Get_Referenced_Object
(Lhs
);
134 Act_Rhs
: Node_Id
:= Get_Referenced_Object
(Rhs
);
136 L_Type
: constant Entity_Id
:=
137 Underlying_Type
(Get_Actual_Subtype
(Act_Lhs
));
138 R_Type
: Entity_Id
:=
139 Underlying_Type
(Get_Actual_Subtype
(Act_Rhs
));
141 L_Slice
: constant Boolean := Nkind
(Act_Lhs
) = N_Slice
;
142 R_Slice
: constant Boolean := Nkind
(Act_Rhs
) = N_Slice
;
144 Crep
: constant Boolean := Change_Of_Representation
(N
);
149 Ndim
: constant Pos
:= Number_Dimensions
(L_Type
);
151 Loop_Required
: Boolean := False;
152 -- This switch is set to True if the array move must be done using
153 -- an explicit front end generated loop.
155 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean;
156 -- Test if Exp is a reference to an array whose declaration has
157 -- an address clause, or it is a slice of such an array.
159 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean;
160 -- Test if Exp is a reference to an array which is either a formal
161 -- parameter or a slice of a formal parameter. These are the cases
162 -- where hidden aliasing can occur.
164 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean;
165 -- Determine if Exp is a reference to an array variable which is other
166 -- than an object defined in the current scope, or a slice of such
167 -- an object. Such objects can be aliased to parameters (unlike local
168 -- array references).
170 function Possible_Unaligned_Slice
(Arg
: Node_Id
) return Boolean;
171 -- Returns True if Arg (either the left or right hand side of the
172 -- assignment) is a slice that could be unaligned wrt the array type.
173 -- This is true if Arg is a component of a packed record, or is
174 -- a record component to which a component clause applies. This
175 -- is a little pessimistic, but the result of an unnecessary
176 -- decision that something is possibly unaligned is only to
177 -- generate a front end loop, which is not so terrible.
178 -- It would really be better if backend handled this ???
180 ------------------------
181 -- Has_Address_Clause --
182 ------------------------
184 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean is
187 (Is_Entity_Name
(Exp
) and then
188 Present
(Address_Clause
(Entity
(Exp
))))
190 (Nkind
(Exp
) = N_Slice
and then Has_Address_Clause
(Prefix
(Exp
)));
191 end Has_Address_Clause
;
193 ---------------------
194 -- Is_Formal_Array --
195 ---------------------
197 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean is
200 (Is_Entity_Name
(Exp
) and then Is_Formal
(Entity
(Exp
)))
202 (Nkind
(Exp
) = N_Slice
and then Is_Formal_Array
(Prefix
(Exp
)));
205 ------------------------
206 -- Is_Non_Local_Array --
207 ------------------------
209 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean is
211 return (Is_Entity_Name
(Exp
)
212 and then Scope
(Entity
(Exp
)) /= Current_Scope
)
213 or else (Nkind
(Exp
) = N_Slice
214 and then Is_Non_Local_Array
(Prefix
(Exp
)));
215 end Is_Non_Local_Array
;
217 ------------------------------
218 -- Possible_Unaligned_Slice --
219 ------------------------------
221 function Possible_Unaligned_Slice
(Arg
: Node_Id
) return Boolean is
223 -- No issue if this is not a slice, or else strict alignment
224 -- is not required in any case.
226 if Nkind
(Arg
) /= N_Slice
227 or else not Target_Strict_Alignment
232 -- No issue if the component type is a byte or byte aligned
235 Array_Typ
: constant Entity_Id
:= Etype
(Arg
);
236 Comp_Typ
: constant Entity_Id
:= Component_Type
(Array_Typ
);
237 Pref
: constant Node_Id
:= Prefix
(Arg
);
240 if Known_Alignment
(Array_Typ
) then
241 if Alignment
(Array_Typ
) = 1 then
245 elsif Known_Component_Size
(Array_Typ
) then
246 if Component_Size
(Array_Typ
) = 1 then
250 elsif Known_Esize
(Comp_Typ
) then
251 if Esize
(Comp_Typ
) <= System_Storage_Unit
then
256 -- No issue if this is not a selected component
258 if Nkind
(Pref
) /= N_Selected_Component
then
262 -- Else we test for a possibly unaligned component
265 Is_Packed
(Etype
(Pref
))
267 Present
(Component_Clause
(Entity
(Selector_Name
(Pref
))));
269 end Possible_Unaligned_Slice
;
271 -- Determine if Lhs, Rhs are formal arrays or non-local arrays
273 Lhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Lhs
);
274 Rhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Rhs
);
276 Lhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Lhs
);
277 Rhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Rhs
);
279 -- Start of processing for Expand_Assign_Array
282 -- Deal with length check, note that the length check is done with
283 -- respect to the right hand side as given, not a possible underlying
284 -- renamed object, since this would generate incorrect extra checks.
286 Apply_Length_Check
(Rhs
, L_Type
);
288 -- We start by assuming that the move can be done in either
289 -- direction, i.e. that the two sides are completely disjoint.
291 Set_Forwards_OK
(N
, True);
292 Set_Backwards_OK
(N
, True);
294 -- Normally it is only the slice case that can lead to overlap,
295 -- and explicit checks for slices are made below. But there is
296 -- one case where the slice can be implicit and invisible to us
297 -- and that is the case where we have a one dimensional array,
298 -- and either both operands are parameters, or one is a parameter
299 -- and the other is a global variable. In this case the parameter
300 -- could be a slice that overlaps with the other parameter.
302 -- Check for the case of slices requiring an explicit loop. Normally
303 -- it is only the explicit slice cases that bother us, but in the
304 -- case of one dimensional arrays, parameters can be slices that
305 -- are passed by reference, so we can have aliasing for assignments
306 -- from one parameter to another, or assignments between parameters
307 -- and non-local variables.
309 -- Note: overlap is never possible if there is a change of
310 -- representation, so we can exclude this case
315 ((Lhs_Formal
and Rhs_Formal
)
317 (Lhs_Formal
and Rhs_Non_Local_Var
)
319 (Rhs_Formal
and Lhs_Non_Local_Var
))
321 -- In the case of compiling for the Java Virtual Machine,
322 -- slices are always passed by making a copy, so we don't
323 -- have to worry about overlap. We also want to prevent
324 -- generation of "<" comparisons for array addresses,
325 -- since that's a meaningless operation on the JVM.
329 Set_Forwards_OK
(N
, False);
330 Set_Backwards_OK
(N
, False);
332 -- Note: the bit-packed case is not worrisome here, since if
333 -- we have a slice passed as a parameter, it is always aligned
334 -- on a byte boundary, and if there are no explicit slices, the
335 -- assignment can be performed directly.
338 -- We certainly must use a loop for change of representation
339 -- and also we use the operand of the conversion on the right
340 -- hand side as the effective right hand side (the component
341 -- types must match in this situation).
344 Act_Rhs
:= Get_Referenced_Object
(Rhs
);
345 R_Type
:= Get_Actual_Subtype
(Act_Rhs
);
346 Loop_Required
:= True;
348 -- Arrays with controlled components are expanded into a loop
349 -- to force calls to adjust at the component level.
351 elsif Has_Controlled_Component
(L_Type
) then
352 Loop_Required
:= True;
354 -- Case where no slice is involved
356 elsif not L_Slice
and not R_Slice
then
358 -- The following code deals with the case of unconstrained bit
359 -- packed arrays. The problem is that the template for such
360 -- arrays contains the bounds of the actual source level array,
362 -- But the copy of an entire array requires the bounds of the
363 -- underlying array. It would be nice if the back end could take
364 -- care of this, but right now it does not know how, so if we
365 -- have such a type, then we expand out into a loop, which is
366 -- inefficient but works correctly. If we don't do this, we
367 -- get the wrong length computed for the array to be moved.
368 -- The two cases we need to worry about are:
370 -- Explicit deference of an unconstrained packed array type as
371 -- in the following example:
374 -- type BITS is array(INTEGER range <>) of BOOLEAN;
375 -- pragma PACK(BITS);
376 -- type A is access BITS;
379 -- P1 := new BITS (1 .. 65_535);
380 -- P2 := new BITS (1 .. 65_535);
384 -- A formal parameter reference with an unconstrained bit
385 -- array type is the other case we need to worry about (here
386 -- we assume the same BITS type declared above:
388 -- procedure Write_All (File : out BITS; Contents : in BITS);
390 -- File.Storage := Contents;
393 -- We expand to a loop in either of these two cases.
395 -- Question for future thought. Another potentially more efficient
396 -- approach would be to create the actual subtype, and then do an
397 -- unchecked conversion to this actual subtype ???
399 Check_Unconstrained_Bit_Packed_Array
: declare
401 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean;
402 -- Function to perform required test for the first case,
403 -- above (dereference of an unconstrained bit packed array)
405 -----------------------
406 -- Is_UBPA_Reference --
407 -----------------------
409 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean is
410 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Opnd
));
412 Des_Type
: Entity_Id
;
415 if Present
(Packed_Array_Type
(Typ
))
416 and then Is_Array_Type
(Packed_Array_Type
(Typ
))
417 and then not Is_Constrained
(Packed_Array_Type
(Typ
))
421 elsif Nkind
(Opnd
) = N_Explicit_Dereference
then
422 P_Type
:= Underlying_Type
(Etype
(Prefix
(Opnd
)));
424 if not Is_Access_Type
(P_Type
) then
428 Des_Type
:= Designated_Type
(P_Type
);
430 Is_Bit_Packed_Array
(Des_Type
)
431 and then not Is_Constrained
(Des_Type
);
437 end Is_UBPA_Reference
;
439 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
442 if Is_UBPA_Reference
(Lhs
)
444 Is_UBPA_Reference
(Rhs
)
446 Loop_Required
:= True;
448 -- Here if we do not have the case of a reference to a bit
449 -- packed unconstrained array case. In this case gigi can
450 -- most certainly handle the assignment if a forwards move
453 -- (could it handle the backwards case also???)
455 elsif Forwards_OK
(N
) then
458 end Check_Unconstrained_Bit_Packed_Array
;
460 -- Gigi can always handle the assignment if the right side is a string
461 -- literal (note that overlap is definitely impossible in this case).
463 elsif Nkind
(Rhs
) = N_String_Literal
then
466 -- If either operand is bit packed, then we need a loop, since we
467 -- can't be sure that the slice is byte aligned. Similarly, if either
468 -- operand is a possibly unaligned slice, then we need a loop (since
469 -- gigi cannot handle unaligned slices).
471 elsif Is_Bit_Packed_Array
(L_Type
)
472 or else Is_Bit_Packed_Array
(R_Type
)
473 or else Possible_Unaligned_Slice
(Lhs
)
474 or else Possible_Unaligned_Slice
(Rhs
)
476 Loop_Required
:= True;
478 -- If we are not bit-packed, and we have only one slice, then no
479 -- overlap is possible except in the parameter case, so we can let
480 -- gigi handle things.
482 elsif not (L_Slice
and R_Slice
) then
483 if Forwards_OK
(N
) then
488 -- Come here to compelete the analysis
490 -- Loop_Required: Set to True if we know that a loop is required
491 -- regardless of overlap considerations.
493 -- Forwards_OK: Set to False if we already know that a forwards
494 -- move is not safe, else set to True.
496 -- Backwards_OK: Set to False if we already know that a backwards
497 -- move is not safe, else set to True
499 -- Our task at this stage is to complete the overlap analysis, which
500 -- can result in possibly setting Forwards_OK or Backwards_OK to
501 -- False, and then generating the final code, either by deciding
502 -- that it is OK after all to let Gigi handle it, or by generating
503 -- appropriate code in the front end.
506 L_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(L_Type
));
507 R_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(R_Type
));
509 Left_Lo
: constant Node_Id
:= Type_Low_Bound
(L_Index_Typ
);
510 Left_Hi
: constant Node_Id
:= Type_High_Bound
(L_Index_Typ
);
511 Right_Lo
: constant Node_Id
:= Type_Low_Bound
(R_Index_Typ
);
512 Right_Hi
: constant Node_Id
:= Type_High_Bound
(R_Index_Typ
);
514 Act_L_Array
: Node_Id
;
515 Act_R_Array
: Node_Id
;
521 Cresult
: Compare_Result
;
524 -- Get the expressions for the arrays. If we are dealing with a
525 -- private type, then convert to the underlying type. We can do
526 -- direct assignments to an array that is a private type, but
527 -- we cannot assign to elements of the array without this extra
528 -- unchecked conversion.
530 if Nkind
(Act_Lhs
) = N_Slice
then
531 Larray
:= Prefix
(Act_Lhs
);
535 if Is_Private_Type
(Etype
(Larray
)) then
538 (Underlying_Type
(Etype
(Larray
)), Larray
);
542 if Nkind
(Act_Rhs
) = N_Slice
then
543 Rarray
:= Prefix
(Act_Rhs
);
547 if Is_Private_Type
(Etype
(Rarray
)) then
550 (Underlying_Type
(Etype
(Rarray
)), Rarray
);
554 -- If both sides are slices, we must figure out whether
555 -- it is safe to do the move in one direction or the other
556 -- It is always safe if there is a change of representation
557 -- since obviously two arrays with different representations
558 -- cannot possibly overlap.
560 if (not Crep
) and L_Slice
and R_Slice
then
561 Act_L_Array
:= Get_Referenced_Object
(Prefix
(Act_Lhs
));
562 Act_R_Array
:= Get_Referenced_Object
(Prefix
(Act_Rhs
));
564 -- If both left and right hand arrays are entity names, and
565 -- refer to different entities, then we know that the move
566 -- is safe (the two storage areas are completely disjoint).
568 if Is_Entity_Name
(Act_L_Array
)
569 and then Is_Entity_Name
(Act_R_Array
)
570 and then Entity
(Act_L_Array
) /= Entity
(Act_R_Array
)
574 -- Otherwise, we assume the worst, which is that the two
575 -- arrays are the same array. There is no need to check if
576 -- we know that is the case, because if we don't know it,
577 -- we still have to assume it!
579 -- Generally if the same array is involved, then we have
580 -- an overlapping case. We will have to really assume the
581 -- worst (i.e. set neither of the OK flags) unless we can
582 -- determine the lower or upper bounds at compile time and
586 Cresult
:= Compile_Time_Compare
(Left_Lo
, Right_Lo
);
588 if Cresult
= Unknown
then
589 Cresult
:= Compile_Time_Compare
(Left_Hi
, Right_Hi
);
593 when LT | LE | EQ
=> Set_Backwards_OK
(N
, False);
594 when GT | GE
=> Set_Forwards_OK
(N
, False);
595 when NE | Unknown
=> Set_Backwards_OK
(N
, False);
596 Set_Forwards_OK
(N
, False);
601 -- If after that analysis, Forwards_OK is still True, and
602 -- Loop_Required is False, meaning that we have not discovered
603 -- some non-overlap reason for requiring a loop, then we can
604 -- still let gigi handle it.
606 if not Loop_Required
then
607 if Forwards_OK
(N
) then
612 -- Here is where a memmove would be appropriate ???
616 -- At this stage we have to generate an explicit loop, and
617 -- we have the following cases:
619 -- Forwards_OK = True
621 -- Rnn : right_index := right_index'First;
622 -- for Lnn in left-index loop
623 -- left (Lnn) := right (Rnn);
624 -- Rnn := right_index'Succ (Rnn);
627 -- Note: the above code MUST be analyzed with checks off,
628 -- because otherwise the Succ could overflow. But in any
629 -- case this is more efficient!
631 -- Forwards_OK = False, Backwards_OK = True
633 -- Rnn : right_index := right_index'Last;
634 -- for Lnn in reverse left-index loop
635 -- left (Lnn) := right (Rnn);
636 -- Rnn := right_index'Pred (Rnn);
639 -- Note: the above code MUST be analyzed with checks off,
640 -- because otherwise the Pred could overflow. But in any
641 -- case this is more efficient!
643 -- Forwards_OK = Backwards_OK = False
645 -- This only happens if we have the same array on each side. It is
646 -- possible to create situations using overlays that violate this,
647 -- but we simply do not promise to get this "right" in this case.
649 -- There are two possible subcases. If the No_Implicit_Conditionals
650 -- restriction is set, then we generate the following code:
653 -- T : constant <operand-type> := rhs;
658 -- If implicit conditionals are permitted, then we generate:
660 -- if Left_Lo <= Right_Lo then
661 -- <code for Forwards_OK = True above>
663 -- <code for Backwards_OK = True above>
666 -- Cases where either Forwards_OK or Backwards_OK is true
668 if Forwards_OK
(N
) or else Backwards_OK
(N
) then
670 Expand_Assign_Array_Loop
671 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
672 Rev
=> not Forwards_OK
(N
)));
674 -- Case of both are false with No_Implicit_Conditionals
676 elsif Restrictions
(No_Implicit_Conditionals
) then
678 T
: Entity_Id
:= Make_Defining_Identifier
(Loc
,
683 Make_Block_Statement
(Loc
,
684 Declarations
=> New_List
(
685 Make_Object_Declaration
(Loc
,
686 Defining_Identifier
=> T
,
687 Constant_Present
=> True,
689 New_Occurrence_Of
(Etype
(Rhs
), Loc
),
690 Expression
=> Relocate_Node
(Rhs
))),
692 Handled_Statement_Sequence
=>
693 Make_Handled_Sequence_Of_Statements
(Loc
,
694 Statements
=> New_List
(
695 Make_Assignment_Statement
(Loc
,
696 Name
=> Relocate_Node
(Lhs
),
697 Expression
=> New_Occurrence_Of
(T
, Loc
))))));
700 -- Case of both are false with implicit conditionals allowed
703 -- Before we generate this code, we must ensure that the
704 -- left and right side array types are defined. They may
705 -- be itypes, and we cannot let them be defined inside the
706 -- if, since the first use in the then may not be executed.
708 Ensure_Defined
(L_Type
, N
);
709 Ensure_Defined
(R_Type
, N
);
711 -- We normally compare addresses to find out which way round
712 -- to do the loop, since this is realiable, and handles the
713 -- cases of parameters, conversions etc. But we can't do that
714 -- in the bit packed case or the Java VM case, because addresses
717 if not Is_Bit_Packed_Array
(L_Type
) and then not Java_VM
then
721 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
722 Make_Attribute_Reference
(Loc
,
724 Make_Indexed_Component
(Loc
,
726 Duplicate_Subexpr
(Larray
, True),
727 Expressions
=> New_List
(
728 Make_Attribute_Reference
(Loc
,
732 Attribute_Name
=> Name_First
))),
733 Attribute_Name
=> Name_Address
)),
736 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
737 Make_Attribute_Reference
(Loc
,
739 Make_Indexed_Component
(Loc
,
741 Duplicate_Subexpr
(Rarray
, True),
742 Expressions
=> New_List
(
743 Make_Attribute_Reference
(Loc
,
747 Attribute_Name
=> Name_First
))),
748 Attribute_Name
=> Name_Address
)));
750 -- For the bit packed and Java VM cases we use the bounds.
751 -- That's OK, because we don't have to worry about parameters,
752 -- since they cannot cause overlap. Perhaps we should worry
753 -- about weird slice conversions ???
756 -- Copy the bounds and reset the Analyzed flag, because the
757 -- bounds of the index type itself may be universal, and must
758 -- must be reaanalyzed to acquire the proper type for Gigi.
760 Cleft_Lo
:= New_Copy_Tree
(Left_Lo
);
761 Cright_Lo
:= New_Copy_Tree
(Right_Lo
);
762 Set_Analyzed
(Cleft_Lo
, False);
763 Set_Analyzed
(Cright_Lo
, False);
767 Left_Opnd
=> Cleft_Lo
,
768 Right_Opnd
=> Cright_Lo
);
772 Make_Implicit_If_Statement
(N
,
773 Condition
=> Condition
,
775 Then_Statements
=> New_List
(
776 Expand_Assign_Array_Loop
777 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
780 Else_Statements
=> New_List
(
781 Expand_Assign_Array_Loop
782 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
786 Analyze
(N
, Suppress
=> All_Checks
);
788 end Expand_Assign_Array
;
790 ------------------------------
791 -- Expand_Assign_Array_Loop --
792 ------------------------------
794 -- The following is an example of the loop generated for the case of
795 -- a two-dimensional array:
800 -- for L1b in 1 .. 100 loop
804 -- for L3b in 1 .. 100 loop
805 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
806 -- R4b := Tm1X2'succ(R4b);
809 -- R2b := Tm1X1'succ(R2b);
813 -- Here Rev is False, and Tm1Xn are the subscript types for the right
814 -- hand side. The declarations of R2b and R4b are inserted before the
815 -- original assignment statement.
817 function Expand_Assign_Array_Loop
827 Loc
: constant Source_Ptr
:= Sloc
(N
);
829 Lnn
: array (1 .. Ndim
) of Entity_Id
;
830 Rnn
: array (1 .. Ndim
) of Entity_Id
;
831 -- Entities used as subscripts on left and right sides
833 L_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
834 R_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
835 -- Left and right index types
847 F_Or_L
:= Name_First
;
851 -- Setup index types and subscript entities
858 L_Index
:= First_Index
(L_Type
);
859 R_Index
:= First_Index
(R_Type
);
861 for J
in 1 .. Ndim
loop
863 Make_Defining_Identifier
(Loc
,
864 Chars
=> New_Internal_Name
('L'));
867 Make_Defining_Identifier
(Loc
,
868 Chars
=> New_Internal_Name
('R'));
870 L_Index_Type
(J
) := Etype
(L_Index
);
871 R_Index_Type
(J
) := Etype
(R_Index
);
873 Next_Index
(L_Index
);
874 Next_Index
(R_Index
);
878 -- Now construct the assignment statement
881 ExprL
: List_Id
:= New_List
;
882 ExprR
: List_Id
:= New_List
;
885 for J
in 1 .. Ndim
loop
886 Append_To
(ExprL
, New_Occurrence_Of
(Lnn
(J
), Loc
));
887 Append_To
(ExprR
, New_Occurrence_Of
(Rnn
(J
), Loc
));
891 Make_Assignment_Statement
(Loc
,
893 Make_Indexed_Component
(Loc
,
894 Prefix
=> Duplicate_Subexpr
(Larray
, Name_Req
=> True),
895 Expressions
=> ExprL
),
897 Make_Indexed_Component
(Loc
,
898 Prefix
=> Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
899 Expressions
=> ExprR
));
901 -- Propagate the No_Ctrl_Actions flag to individual assignments
903 Set_No_Ctrl_Actions
(Assign
, No_Ctrl_Actions
(N
));
906 -- Now construct the loop from the inside out, with the last subscript
907 -- varying most rapidly. Note that Assign is first the raw assignment
908 -- statement, and then subsequently the loop that wraps it up.
910 for J
in reverse 1 .. Ndim
loop
912 Make_Block_Statement
(Loc
,
913 Declarations
=> New_List
(
914 Make_Object_Declaration
(Loc
,
915 Defining_Identifier
=> Rnn
(J
),
917 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
919 Make_Attribute_Reference
(Loc
,
920 Prefix
=> New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
921 Attribute_Name
=> F_Or_L
))),
923 Handled_Statement_Sequence
=>
924 Make_Handled_Sequence_Of_Statements
(Loc
,
925 Statements
=> New_List
(
926 Make_Implicit_Loop_Statement
(N
,
928 Make_Iteration_Scheme
(Loc
,
929 Loop_Parameter_Specification
=>
930 Make_Loop_Parameter_Specification
(Loc
,
931 Defining_Identifier
=> Lnn
(J
),
932 Reverse_Present
=> Rev
,
933 Discrete_Subtype_Definition
=>
934 New_Reference_To
(L_Index_Type
(J
), Loc
))),
936 Statements
=> New_List
(
939 Make_Assignment_Statement
(Loc
,
940 Name
=> New_Occurrence_Of
(Rnn
(J
), Loc
),
942 Make_Attribute_Reference
(Loc
,
944 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
945 Attribute_Name
=> S_Or_P
,
946 Expressions
=> New_List
(
947 New_Occurrence_Of
(Rnn
(J
), Loc
)))))))));
951 end Expand_Assign_Array_Loop
;
953 --------------------------
954 -- Expand_Assign_Record --
955 --------------------------
957 -- The only processing required is in the change of representation
958 -- case, where we must expand the assignment to a series of field
959 -- by field assignments.
961 procedure Expand_Assign_Record
(N
: Node_Id
) is
963 if not Change_Of_Representation
(N
) then
967 -- At this stage we know that the right hand side is a conversion
970 Loc
: constant Source_Ptr
:= Sloc
(N
);
971 Lhs
: constant Node_Id
:= Name
(N
);
972 Rhs
: constant Node_Id
:= Expression
(Expression
(N
));
973 R_Rec
: constant Node_Id
:= Expression
(Expression
(N
));
974 R_Typ
: constant Entity_Id
:= Base_Type
(Etype
(R_Rec
));
975 L_Typ
: constant Entity_Id
:= Etype
(Lhs
);
976 Decl
: constant Node_Id
:= Declaration_Node
(R_Typ
);
980 function Find_Component
984 -- Find the component with the given name in the underlying record
985 -- declaration for Typ. We need to use the actual entity because
986 -- the type may be private and resolution by identifier alone would
989 function Make_Component_List_Assign
(CL
: Node_Id
) return List_Id
;
990 -- Returns a sequence of statements to assign the components that
991 -- are referenced in the given component list.
993 function Make_Field_Assign
(C
: Entity_Id
) return Node_Id
;
994 -- Given C, the entity for a discriminant or component, build
995 -- an assignment for the corresponding field values.
997 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
;
998 -- Given CI, a component items list, construct series of statements
999 -- for fieldwise assignment of the corresponding components.
1001 --------------------
1002 -- Find_Component --
1003 --------------------
1005 function Find_Component
1011 Utyp
: constant Entity_Id
:= Underlying_Type
(Typ
);
1015 C
:= First_Entity
(Utyp
);
1017 while Present
(C
) loop
1018 if Chars
(C
) = Chars
(Comp
) then
1024 raise Program_Error
;
1027 --------------------------------
1028 -- Make_Component_List_Assign --
1029 --------------------------------
1031 function Make_Component_List_Assign
(CL
: Node_Id
) return List_Id
is
1032 CI
: constant List_Id
:= Component_Items
(CL
);
1033 VP
: constant Node_Id
:= Variant_Part
(CL
);
1042 Result
:= Make_Field_Assigns
(CI
);
1044 if Present
(VP
) then
1046 V
:= First_Non_Pragma
(Variants
(VP
));
1048 while Present
(V
) loop
1051 DC
:= First
(Discrete_Choices
(V
));
1052 while Present
(DC
) loop
1053 Append_To
(DCH
, New_Copy_Tree
(DC
));
1058 Make_Case_Statement_Alternative
(Loc
,
1059 Discrete_Choices
=> DCH
,
1061 Make_Component_List_Assign
(Component_List
(V
))));
1062 Next_Non_Pragma
(V
);
1066 Make_Case_Statement
(Loc
,
1068 Make_Selected_Component
(Loc
,
1069 Prefix
=> Duplicate_Subexpr
(Rhs
),
1071 Make_Identifier
(Loc
, Chars
(Name
(VP
)))),
1072 Alternatives
=> Alts
));
1077 end Make_Component_List_Assign
;
1079 -----------------------
1080 -- Make_Field_Assign --
1081 -----------------------
1083 function Make_Field_Assign
(C
: Entity_Id
) return Node_Id
is
1088 Make_Assignment_Statement
(Loc
,
1090 Make_Selected_Component
(Loc
,
1091 Prefix
=> Duplicate_Subexpr
(Lhs
),
1093 New_Occurrence_Of
(Find_Component
(L_Typ
, C
), Loc
)),
1095 Make_Selected_Component
(Loc
,
1096 Prefix
=> Duplicate_Subexpr
(Rhs
),
1097 Selector_Name
=> New_Occurrence_Of
(C
, Loc
)));
1099 -- Set Assignment_OK, so discriminants can be assigned
1101 Set_Assignment_OK
(Name
(A
), True);
1103 end Make_Field_Assign
;
1105 ------------------------
1106 -- Make_Field_Assigns --
1107 ------------------------
1109 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
is
1117 while Present
(Item
) loop
1118 if Nkind
(Item
) = N_Component_Declaration
then
1120 (Result
, Make_Field_Assign
(Defining_Identifier
(Item
)));
1127 end Make_Field_Assigns
;
1129 -- Start of processing for Expand_Assign_Record
1132 -- Note that we use the base type for this processing. This results
1133 -- in some extra work in the constrained case, but the change of
1134 -- representation case is so unusual that it is not worth the effort.
1136 -- First copy the discriminants. This is done unconditionally. It
1137 -- is required in the unconstrained left side case, and also in the
1138 -- case where this assignment was constructed during the expansion
1139 -- of a type conversion (since initialization of discriminants is
1140 -- suppressed in this case). It is unnecessary but harmless in
1143 if Has_Discriminants
(L_Typ
) then
1144 F
:= First_Discriminant
(R_Typ
);
1145 while Present
(F
) loop
1146 Insert_Action
(N
, Make_Field_Assign
(F
));
1147 Next_Discriminant
(F
);
1151 -- We know the underlying type is a record, but its current view
1152 -- may be private. We must retrieve the usable record declaration.
1154 if Nkind
(Decl
) = N_Private_Type_Declaration
1155 and then Present
(Full_View
(R_Typ
))
1157 RDef
:= Type_Definition
(Declaration_Node
(Full_View
(R_Typ
)));
1159 RDef
:= Type_Definition
(Decl
);
1162 if Nkind
(RDef
) = N_Record_Definition
1163 and then Present
(Component_List
(RDef
))
1166 (N
, Make_Component_List_Assign
(Component_List
(RDef
)));
1168 Rewrite
(N
, Make_Null_Statement
(Loc
));
1172 end Expand_Assign_Record
;
1174 -----------------------------------
1175 -- Expand_N_Assignment_Statement --
1176 -----------------------------------
1178 -- For array types, deal with slice assignments and setting the flags
1179 -- to indicate if it can be statically determined which direction the
1180 -- move should go in. Also deal with generating length checks.
1182 procedure Expand_N_Assignment_Statement
(N
: Node_Id
) is
1183 Loc
: constant Source_Ptr
:= Sloc
(N
);
1184 Lhs
: constant Node_Id
:= Name
(N
);
1185 Rhs
: constant Node_Id
:= Expression
(N
);
1186 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Lhs
));
1190 -- Check for a special case where a high level transformation is
1191 -- required. If we have either of:
1196 -- where P is a reference to a bit packed array, then we have to unwind
1197 -- the assignment. The exact meaning of being a reference to a bit
1198 -- packed array is as follows:
1200 -- An indexed component whose prefix is a bit packed array is a
1201 -- reference to a bit packed array.
1203 -- An indexed component or selected component whose prefix is a
1204 -- reference to a bit packed array is itself a reference ot a
1205 -- bit packed array.
1207 -- The required transformation is
1209 -- Tnn : prefix_type := P;
1210 -- Tnn.field := rhs;
1215 -- Tnn : prefix_type := P;
1216 -- Tnn (subscr) := rhs;
1219 -- Since P is going to be evaluated more than once, any subscripts
1220 -- in P must have their evaluation forced.
1222 if (Nkind
(Lhs
) = N_Indexed_Component
1224 Nkind
(Lhs
) = N_Selected_Component
)
1225 and then Is_Ref_To_Bit_Packed_Array
(Prefix
(Lhs
))
1228 BPAR_Expr
: constant Node_Id
:= Relocate_Node
(Prefix
(Lhs
));
1229 BPAR_Typ
: constant Entity_Id
:= Etype
(BPAR_Expr
);
1230 Tnn
: constant Entity_Id
:=
1231 Make_Defining_Identifier
(Loc
,
1232 Chars
=> New_Internal_Name
('T'));
1235 -- Insert the post assignment first, because we want to copy
1236 -- the BPAR_Expr tree before it gets analyzed in the context
1237 -- of the pre assignment. Note that we do not analyze the
1238 -- post assignment yet (we cannot till we have completed the
1239 -- analysis of the pre assignment). As usual, the analysis
1240 -- of this post assignment will happen on its own when we
1241 -- "run into" it after finishing the current assignment.
1244 Make_Assignment_Statement
(Loc
,
1245 Name
=> New_Copy_Tree
(BPAR_Expr
),
1246 Expression
=> New_Occurrence_Of
(Tnn
, Loc
)));
1248 -- At this stage BPAR_Expr is a reference to a bit packed
1249 -- array where the reference was not expanded in the original
1250 -- tree, since it was on the left side of an assignment. But
1251 -- in the pre-assignment statement (the object definition),
1252 -- BPAR_Expr will end up on the right hand side, and must be
1253 -- reexpanded. To achieve this, we reset the analyzed flag
1254 -- of all selected and indexed components down to the actual
1255 -- indexed component for the packed array.
1259 Set_Analyzed
(Exp
, False);
1261 if Nkind
(Exp
) = N_Selected_Component
1263 Nkind
(Exp
) = N_Indexed_Component
1265 Exp
:= Prefix
(Exp
);
1271 -- Now we can insert and analyze the pre-assignment.
1273 -- If the right-hand side requires a transient scope, it has
1274 -- already been placed on the stack. However, the declaration is
1275 -- inserted in the tree outside of this scope, and must reflect
1276 -- the proper scope for its variable. This awkward bit is forced
1277 -- by the stricter scope discipline imposed by GCC 2.97.
1280 Uses_Transient_Scope
: constant Boolean :=
1281 Scope_Is_Transient
and then N
= Node_To_Be_Wrapped
;
1284 if Uses_Transient_Scope
then
1285 New_Scope
(Scope
(Current_Scope
));
1288 Insert_Before_And_Analyze
(N
,
1289 Make_Object_Declaration
(Loc
,
1290 Defining_Identifier
=> Tnn
,
1291 Object_Definition
=> New_Occurrence_Of
(BPAR_Typ
, Loc
),
1292 Expression
=> BPAR_Expr
));
1294 if Uses_Transient_Scope
then
1299 -- Now fix up the original assignment and continue processing
1301 Rewrite
(Prefix
(Lhs
),
1302 New_Occurrence_Of
(Tnn
, Loc
));
1306 -- When we have the appropriate type of aggregate in the
1307 -- expression (it has been determined during analysis of the
1308 -- aggregate by setting the delay flag), let's perform in place
1309 -- assignment and thus avoid creating a temporay.
1311 if Is_Delayed_Aggregate
(Rhs
) then
1312 Convert_Aggr_In_Assignment
(N
);
1313 Rewrite
(N
, Make_Null_Statement
(Loc
));
1318 -- Apply discriminant check if required. If Lhs is an access type
1319 -- to a designated type with discriminants, we must always check.
1321 if Has_Discriminants
(Etype
(Lhs
)) then
1323 -- Skip discriminant check if change of representation. Will be
1324 -- done when the change of representation is expanded out.
1326 if not Change_Of_Representation
(N
) then
1327 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
), Lhs
);
1330 -- If the type is private without discriminants, and the full type
1331 -- has discriminants (necessarily with defaults) a check may still be
1332 -- necessary if the Lhs is aliased. The private determinants must be
1333 -- visible to build the discriminant constraints.
1335 elsif Is_Private_Type
(Etype
(Lhs
))
1336 and then Has_Discriminants
(Typ
)
1337 and then Nkind
(Lhs
) = N_Explicit_Dereference
1340 Lt
: constant Entity_Id
:= Etype
(Lhs
);
1342 Set_Etype
(Lhs
, Typ
);
1343 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
1344 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
1345 Set_Etype
(Lhs
, Lt
);
1348 -- If the Lhs has a private type with unknown discriminants, it
1349 -- may have a full view with discriminants, but those are nameable
1350 -- only in the underlying type, so convert the Rhs to it before
1351 -- potential checking.
1353 elsif Has_Unknown_Discriminants
(Base_Type
(Etype
(Lhs
)))
1354 and then Has_Discriminants
(Typ
)
1356 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
1357 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
1359 -- In the access type case, we need the same discriminant check,
1360 -- and also range checks if we have an access to constrained array.
1362 elsif Is_Access_Type
(Etype
(Lhs
))
1363 and then Is_Constrained
(Designated_Type
(Etype
(Lhs
)))
1365 if Has_Discriminants
(Designated_Type
(Etype
(Lhs
))) then
1367 -- Skip discriminant check if change of representation. Will be
1368 -- done when the change of representation is expanded out.
1370 if not Change_Of_Representation
(N
) then
1371 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
));
1374 elsif Is_Array_Type
(Designated_Type
(Etype
(Lhs
))) then
1375 Apply_Range_Check
(Rhs
, Etype
(Lhs
));
1377 if Is_Constrained
(Etype
(Lhs
)) then
1378 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
1381 if Nkind
(Rhs
) = N_Allocator
then
1383 Target_Typ
: constant Entity_Id
:= Etype
(Expression
(Rhs
));
1384 C_Es
: Check_Result
;
1391 Etype
(Designated_Type
(Etype
(Lhs
))));
1403 -- Apply range check for access type case
1405 elsif Is_Access_Type
(Etype
(Lhs
))
1406 and then Nkind
(Rhs
) = N_Allocator
1407 and then Nkind
(Expression
(Rhs
)) = N_Qualified_Expression
1409 Analyze_And_Resolve
(Expression
(Rhs
));
1411 (Expression
(Rhs
), Designated_Type
(Etype
(Lhs
)));
1414 -- Case of assignment to a bit packed array element
1416 if Nkind
(Lhs
) = N_Indexed_Component
1417 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Lhs
)))
1419 Expand_Bit_Packed_Element_Set
(N
);
1422 -- Case of tagged type assignment
1424 elsif Is_Tagged_Type
(Typ
)
1425 or else (Controlled_Type
(Typ
) and then not Is_Array_Type
(Typ
))
1427 Tagged_Case
: declare
1428 L
: List_Id
:= No_List
;
1429 Expand_Ctrl_Actions
: constant Boolean := not No_Ctrl_Actions
(N
);
1432 -- In the controlled case, we need to make sure that function
1433 -- calls are evaluated before finalizing the target. In all
1434 -- cases, it makes the expansion easier if the side-effects
1435 -- are removed first.
1437 Remove_Side_Effects
(Lhs
);
1438 Remove_Side_Effects
(Rhs
);
1440 -- Avoid recursion in the mechanism
1444 -- If dispatching assignment, we need to dispatch to _assign
1446 if Is_Class_Wide_Type
(Typ
)
1448 -- If the type is tagged, we may as well use the predefined
1449 -- primitive assignment. This avoids inlining a lot of code
1450 -- and in the class-wide case, the assignment is replaced by
1451 -- a dispatch call to _assign. Note that this cannot be done
1452 -- when discriminant checks are locally suppressed (as in
1453 -- extension aggregate expansions) because otherwise the
1454 -- discriminant check will be performed within the _assign
1457 or else (Is_Tagged_Type
(Typ
)
1458 and then Chars
(Current_Scope
) /= Name_uAssign
1459 and then Expand_Ctrl_Actions
1460 and then not Discriminant_Checks_Suppressed
(Empty
))
1462 -- Fetch the primitive op _assign and proper type to call
1463 -- it. Because of possible conflits between private and
1464 -- full view the proper type is fetched directly from the
1465 -- operation profile.
1468 Op
: constant Entity_Id
1469 := Find_Prim_Op
(Typ
, Name_uAssign
);
1470 F_Typ
: Entity_Id
:= Etype
(First_Formal
(Op
));
1473 -- If the assignment is dispatching, make sure to use the
1474 -- ??? where is rest of this comment ???
1476 if Is_Class_Wide_Type
(Typ
) then
1477 F_Typ
:= Class_Wide_Type
(F_Typ
);
1481 Make_Procedure_Call_Statement
(Loc
,
1482 Name
=> New_Reference_To
(Op
, Loc
),
1483 Parameter_Associations
=> New_List
(
1484 Unchecked_Convert_To
(F_Typ
, Duplicate_Subexpr
(Lhs
)),
1485 Unchecked_Convert_To
(F_Typ
,
1486 Duplicate_Subexpr
(Rhs
)))));
1490 L
:= Make_Tag_Ctrl_Assignment
(N
);
1492 -- We can't afford to have destructive Finalization Actions
1493 -- in the Self assignment case, so if the target and the
1494 -- source are not obviously different, code is generated to
1495 -- avoid the self assignment case
1497 -- if lhs'address /= rhs'address then
1498 -- <code for controlled and/or tagged assignment>
1501 if not Statically_Different
(Lhs
, Rhs
)
1502 and then Expand_Ctrl_Actions
1505 Make_Implicit_If_Statement
(N
,
1509 Make_Attribute_Reference
(Loc
,
1510 Prefix
=> Duplicate_Subexpr
(Lhs
),
1511 Attribute_Name
=> Name_Address
),
1514 Make_Attribute_Reference
(Loc
,
1515 Prefix
=> Duplicate_Subexpr
(Rhs
),
1516 Attribute_Name
=> Name_Address
)),
1518 Then_Statements
=> L
));
1521 -- We need to set up an exception handler for implementing
1522 -- 7.6.1 (18). The remaining adjustments are tackled by the
1523 -- implementation of adjust for record_controllers (see
1526 -- This is skipped in No_Run_Time mode, where we in any
1527 -- case exclude the possibility of finalization going on!
1529 if Expand_Ctrl_Actions
and then not No_Run_Time
then
1531 Make_Block_Statement
(Loc
,
1532 Handled_Statement_Sequence
=>
1533 Make_Handled_Sequence_Of_Statements
(Loc
,
1535 Exception_Handlers
=> New_List
(
1536 Make_Exception_Handler
(Loc
,
1537 Exception_Choices
=>
1538 New_List
(Make_Others_Choice
(Loc
)),
1539 Statements
=> New_List
(
1540 Make_Raise_Program_Error
(Loc
,
1542 PE_Finalize_Raised_Exception
)
1548 Make_Block_Statement
(Loc
,
1549 Handled_Statement_Sequence
=>
1550 Make_Handled_Sequence_Of_Statements
(Loc
, Statements
=> L
)));
1552 -- If no restrictions on aborts, protect the whole assignement
1553 -- for controlled objects as per 9.8(11)
1555 if Controlled_Type
(Typ
)
1556 and then Expand_Ctrl_Actions
1557 and then Abort_Allowed
1560 Blk
: constant Entity_Id
:=
1561 New_Internal_Entity
(
1562 E_Block
, Current_Scope
, Sloc
(N
), 'B');
1565 Set_Scope
(Blk
, Current_Scope
);
1566 Set_Etype
(Blk
, Standard_Void_Type
);
1567 Set_Identifier
(N
, New_Occurrence_Of
(Blk
, Sloc
(N
)));
1569 Prepend_To
(L
, Build_Runtime_Call
(Loc
, RE_Abort_Defer
));
1570 Set_At_End_Proc
(Handled_Statement_Sequence
(N
),
1571 New_Occurrence_Of
(RTE
(RE_Abort_Undefer_Direct
), Loc
));
1572 Expand_At_End_Handler
1573 (Handled_Statement_Sequence
(N
), Blk
);
1583 elsif Is_Array_Type
(Typ
) then
1585 Actual_Rhs
: Node_Id
:= Rhs
;
1588 while Nkind
(Actual_Rhs
) = N_Type_Conversion
1590 Nkind
(Actual_Rhs
) = N_Qualified_Expression
1592 Actual_Rhs
:= Expression
(Actual_Rhs
);
1595 Expand_Assign_Array
(N
, Actual_Rhs
);
1601 elsif Is_Record_Type
(Typ
) then
1602 Expand_Assign_Record
(N
);
1605 -- Scalar types. This is where we perform the processing related
1606 -- to the requirements of (RM 13.9.1(9-11)) concerning the handling
1607 -- of invalid scalar values.
1609 elsif Is_Scalar_Type
(Typ
) then
1611 -- Case where right side is known valid
1613 if Expr_Known_Valid
(Rhs
) then
1615 -- Here the right side is valid, so it is fine. The case to
1616 -- deal with is when the left side is a local variable reference
1617 -- whose value is not currently known to be valid. If this is
1618 -- the case, and the assignment appears in an unconditional
1619 -- context, then we can mark the left side as now being valid.
1621 if Is_Local_Variable_Reference
(Lhs
)
1622 and then not Is_Known_Valid
(Entity
(Lhs
))
1623 and then In_Unconditional_Context
(N
)
1625 Set_Is_Known_Valid
(Entity
(Lhs
), True);
1628 -- Case where right side may be invalid in the sense of the RM
1629 -- reference above. The RM does not require that we check for
1630 -- the validity on an assignment, but it does require that the
1631 -- assignment of an invalid value not cause erroneous behavior.
1633 -- The general approach in GNAT is to use the Is_Known_Valid flag
1634 -- to avoid the need for validity checking on assignments. However
1635 -- in some cases, we have to do validity checking in order to make
1636 -- sure that the setting of this flag is correct.
1639 -- Validate right side if we are validating copies
1641 if Validity_Checks_On
1642 and then Validity_Check_Copies
1646 -- We can propagate this to the left side where appropriate
1648 if Is_Local_Variable_Reference
(Lhs
)
1649 and then not Is_Known_Valid
(Entity
(Lhs
))
1650 and then In_Unconditional_Context
(N
)
1652 Set_Is_Known_Valid
(Entity
(Lhs
), True);
1655 -- Otherwise check to see what should be done
1657 -- If left side is a local variable, then we just set its
1658 -- flag to indicate that its value may no longer be valid,
1659 -- since we are copying a potentially invalid value.
1661 elsif Is_Local_Variable_Reference
(Lhs
) then
1662 Set_Is_Known_Valid
(Entity
(Lhs
), False);
1664 -- Check for case of a non-local variable on the left side
1665 -- which is currently known to be valid. In this case, we
1666 -- simply ensure that the right side is valid. We only play
1667 -- the game of copying validity status for local variables,
1668 -- since we are doing this statically, not by tracing the
1671 elsif Is_Entity_Name
(Lhs
)
1672 and then Is_Known_Valid
(Entity
(Lhs
))
1674 -- Note that the Ensure_Valid call is ignored if the
1675 -- Validity_Checking mode is set to none so we do not
1676 -- need to worry about that case here.
1680 -- In all other cases, we can safely copy an invalid value
1681 -- without worrying about the status of the left side. Since
1682 -- it is not a variable reference it will not be considered
1683 -- as being known to be valid in any case.
1691 -- Defend against invalid subscripts on left side if we are in
1692 -- standard validity checking mode. No need to do this if we
1693 -- are checking all subscripts.
1695 if Validity_Checks_On
1696 and then Validity_Check_Default
1697 and then not Validity_Check_Subscripts
1699 Check_Valid_Lvalue_Subscripts
(Lhs
);
1701 end Expand_N_Assignment_Statement
;
1703 ------------------------------
1704 -- Expand_N_Block_Statement --
1705 ------------------------------
1707 -- Encode entity names defined in block statement
1709 procedure Expand_N_Block_Statement
(N
: Node_Id
) is
1711 Qualify_Entity_Names
(N
);
1712 end Expand_N_Block_Statement
;
1714 -----------------------------
1715 -- Expand_N_Case_Statement --
1716 -----------------------------
1718 procedure Expand_N_Case_Statement
(N
: Node_Id
) is
1719 Loc
: constant Source_Ptr
:= Sloc
(N
);
1720 Expr
: constant Node_Id
:= Expression
(N
);
1723 -- Check for the situation where we know at compile time which
1724 -- branch will be taken
1726 if Compile_Time_Known_Value
(Expr
) then
1728 Val
: constant Uint
:= Expr_Value
(Expr
);
1733 Alt
:= First
(Alternatives
(N
));
1735 Choice
:= First
(Discrete_Choices
(Alt
));
1736 while Present
(Choice
) loop
1738 -- Others choice, always matches
1740 if Nkind
(Choice
) = N_Others_Choice
then
1743 -- Range, check if value is in the range
1745 elsif Nkind
(Choice
) = N_Range
then
1747 Val
>= Expr_Value
(Low_Bound
(Choice
))
1749 Val
<= Expr_Value
(High_Bound
(Choice
));
1751 -- Choice is a subtype name. Note that we know it must
1752 -- be a static subtype, since otherwise it would have
1753 -- been diagnosed as illegal.
1755 elsif Is_Entity_Name
(Choice
)
1756 and then Is_Type
(Entity
(Choice
))
1758 exit when Is_In_Range
(Expr
, Etype
(Choice
));
1760 -- Choice is a subtype indication
1762 elsif Nkind
(Choice
) = N_Subtype_Indication
then
1764 C
: constant Node_Id
:= Constraint
(Choice
);
1765 R
: constant Node_Id
:= Range_Expression
(C
);
1769 Val
>= Expr_Value
(Low_Bound
(R
))
1771 Val
<= Expr_Value
(High_Bound
(R
));
1774 -- Choice is a simple expression
1777 exit Search
when Val
= Expr_Value
(Choice
);
1784 pragma Assert
(Present
(Alt
));
1787 -- The above loop *must* terminate by finding a match, since
1788 -- we know the case statement is valid, and the value of the
1789 -- expression is known at compile time. When we fall out of
1790 -- the loop, Alt points to the alternative that we know will
1791 -- be selected at run time.
1793 -- Move the statements from this alternative after the case
1794 -- statement. They are already analyzed, so will be skipped
1797 Insert_List_After
(N
, Statements
(Alt
));
1799 -- That leaves the case statement as a shell. The alternative
1800 -- that wlil be executed is reset to a null list. So now we can
1801 -- kill the entire case statement.
1803 Kill_Dead_Code
(Expression
(N
));
1804 Kill_Dead_Code
(Alternatives
(N
));
1805 Rewrite
(N
, Make_Null_Statement
(Loc
));
1808 -- Here if the choice is not determined at compile time
1810 -- If the last alternative is not an Others choice, replace it with an
1811 -- N_Others_Choice. Note that we do not bother to call Analyze on the
1812 -- modified case statement, since it's only effect would be to compute
1813 -- the contents of the Others_Discrete_Choices node laboriously, and of
1814 -- course we already know the list of choices that corresponds to the
1815 -- others choice (it's the list we are replacing!)
1819 Altnode
: constant Node_Id
:= Last
(Alternatives
(N
));
1820 Others_Node
: Node_Id
;
1823 if Nkind
(First
(Discrete_Choices
(Altnode
)))
1826 Others_Node
:= Make_Others_Choice
(Sloc
(Altnode
));
1827 Set_Others_Discrete_Choices
1828 (Others_Node
, Discrete_Choices
(Altnode
));
1829 Set_Discrete_Choices
(Altnode
, New_List
(Others_Node
));
1832 -- If checks are on, ensure argument is valid (RM 5.4(13)). This
1833 -- is only done for case statements frpm in the source program.
1834 -- We don't just call Ensure_Valid here, because the requirement
1835 -- is more strenous than usual, in that it is required that
1836 -- Constraint_Error be raised.
1838 if Comes_From_Source
(N
)
1839 and then Validity_Checks_On
1840 and then Validity_Check_Default
1841 and then not Expr_Known_Valid
(Expr
)
1843 Insert_Valid_Check
(Expr
);
1847 end Expand_N_Case_Statement
;
1849 -----------------------------
1850 -- Expand_N_Exit_Statement --
1851 -----------------------------
1853 -- The only processing required is to deal with a possible C/Fortran
1854 -- boolean value used as the condition for the exit statement.
1856 procedure Expand_N_Exit_Statement
(N
: Node_Id
) is
1858 Adjust_Condition
(Condition
(N
));
1859 end Expand_N_Exit_Statement
;
1861 -----------------------------
1862 -- Expand_N_Goto_Statement --
1863 -----------------------------
1865 -- Add poll before goto if polling active
1867 procedure Expand_N_Goto_Statement
(N
: Node_Id
) is
1869 Generate_Poll_Call
(N
);
1870 end Expand_N_Goto_Statement
;
1872 ---------------------------
1873 -- Expand_N_If_Statement --
1874 ---------------------------
1876 -- First we deal with the case of C and Fortran convention boolean
1877 -- values, with zero/non-zero semantics.
1879 -- Second, we deal with the obvious rewriting for the cases where the
1880 -- condition of the IF is known at compile time to be True or False.
1882 -- Third, we remove elsif parts which have non-empty Condition_Actions
1883 -- and rewrite as independent if statements. For example:
1894 -- <<condition actions of y>>
1900 -- This rewriting is needed if at least one elsif part has a non-empty
1901 -- Condition_Actions list. We also do the same processing if there is
1902 -- a constant condition in an elsif part (in conjunction with the first
1903 -- processing step mentioned above, for the recursive call made to deal
1904 -- with the created inner if, this deals with properly optimizing the
1905 -- cases of constant elsif conditions).
1907 procedure Expand_N_If_Statement
(N
: Node_Id
) is
1913 Adjust_Condition
(Condition
(N
));
1915 -- The following loop deals with constant conditions for the IF. We
1916 -- need a loop because as we eliminate False conditions, we grab the
1917 -- first elsif condition and use it as the primary condition.
1919 while Compile_Time_Known_Value
(Condition
(N
)) loop
1921 -- If condition is True, we can simply rewrite the if statement
1922 -- now by replacing it by the series of then statements.
1924 if Is_True
(Expr_Value
(Condition
(N
))) then
1926 -- All the else parts can be killed
1928 Kill_Dead_Code
(Elsif_Parts
(N
));
1929 Kill_Dead_Code
(Else_Statements
(N
));
1931 Hed
:= Remove_Head
(Then_Statements
(N
));
1932 Insert_List_After
(N
, Then_Statements
(N
));
1936 -- If condition is False, then we can delete the condition and
1937 -- the Then statements
1940 -- We do not delete the condition if constant condition
1941 -- warnings are enabled, since otherwise we end up deleting
1942 -- the desired warning. Of course the backend will get rid
1943 -- of this True/False test anyway, so nothing is lost here.
1945 if not Constant_Condition_Warnings
then
1946 Kill_Dead_Code
(Condition
(N
));
1949 Kill_Dead_Code
(Then_Statements
(N
));
1951 -- If there are no elsif statements, then we simply replace
1952 -- the entire if statement by the sequence of else statements.
1954 if No
(Elsif_Parts
(N
)) then
1956 if No
(Else_Statements
(N
))
1957 or else Is_Empty_List
(Else_Statements
(N
))
1960 Make_Null_Statement
(Sloc
(N
)));
1963 Hed
:= Remove_Head
(Else_Statements
(N
));
1964 Insert_List_After
(N
, Else_Statements
(N
));
1970 -- If there are elsif statements, the first of them becomes
1971 -- the if/then section of the rebuilt if statement This is
1972 -- the case where we loop to reprocess this copied condition.
1975 Hed
:= Remove_Head
(Elsif_Parts
(N
));
1976 Insert_Actions
(N
, Condition_Actions
(Hed
));
1977 Set_Condition
(N
, Condition
(Hed
));
1978 Set_Then_Statements
(N
, Then_Statements
(Hed
));
1980 if Is_Empty_List
(Elsif_Parts
(N
)) then
1981 Set_Elsif_Parts
(N
, No_List
);
1987 -- Loop through elsif parts, dealing with constant conditions and
1988 -- possible expression actions that are present.
1990 if Present
(Elsif_Parts
(N
)) then
1991 E
:= First
(Elsif_Parts
(N
));
1992 while Present
(E
) loop
1993 Adjust_Condition
(Condition
(E
));
1995 -- If there are condition actions, then we rewrite the if
1996 -- statement as indicated above. We also do the same rewrite
1997 -- if the condition is True or False. The further processing
1998 -- of this constant condition is then done by the recursive
1999 -- call to expand the newly created if statement
2001 if Present
(Condition_Actions
(E
))
2002 or else Compile_Time_Known_Value
(Condition
(E
))
2004 -- Note this is not an implicit if statement, since it is
2005 -- part of an explicit if statement in the source (or of an
2006 -- implicit if statement that has already been tested).
2009 Make_If_Statement
(Sloc
(E
),
2010 Condition
=> Condition
(E
),
2011 Then_Statements
=> Then_Statements
(E
),
2012 Elsif_Parts
=> No_List
,
2013 Else_Statements
=> Else_Statements
(N
));
2015 -- Elsif parts for new if come from remaining elsif's of parent
2017 while Present
(Next
(E
)) loop
2018 if No
(Elsif_Parts
(New_If
)) then
2019 Set_Elsif_Parts
(New_If
, New_List
);
2022 Append
(Remove_Next
(E
), Elsif_Parts
(New_If
));
2025 Set_Else_Statements
(N
, New_List
(New_If
));
2027 if Present
(Condition_Actions
(E
)) then
2028 Insert_List_Before
(New_If
, Condition_Actions
(E
));
2033 if Is_Empty_List
(Elsif_Parts
(N
)) then
2034 Set_Elsif_Parts
(N
, No_List
);
2040 -- No special processing for that elsif part, move to next
2047 end Expand_N_If_Statement
;
2049 -----------------------------
2050 -- Expand_N_Loop_Statement --
2051 -----------------------------
2053 -- 1. Deal with while condition for C/Fortran boolean
2054 -- 2. Deal with loops with a non-standard enumeration type range
2055 -- 3. Deal with while loops where Condition_Actions is set
2056 -- 4. Insert polling call if required
2058 procedure Expand_N_Loop_Statement
(N
: Node_Id
) is
2059 Loc
: constant Source_Ptr
:= Sloc
(N
);
2060 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
2063 if Present
(Isc
) then
2064 Adjust_Condition
(Condition
(Isc
));
2067 if Is_Non_Empty_List
(Statements
(N
)) then
2068 Generate_Poll_Call
(First
(Statements
(N
)));
2075 -- Handle the case where we have a for loop with the range type being
2076 -- an enumeration type with non-standard representation. In this case
2079 -- for x in [reverse] a .. b loop
2085 -- for xP in [reverse] integer
2086 -- range etype'Pos (a) .. etype'Pos (b) loop
2088 -- x : constant etype := Pos_To_Rep (xP);
2094 if Present
(Loop_Parameter_Specification
(Isc
)) then
2096 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Isc
);
2097 Loop_Id
: constant Entity_Id
:= Defining_Identifier
(LPS
);
2098 Ltype
: constant Entity_Id
:= Etype
(Loop_Id
);
2099 Btype
: constant Entity_Id
:= Base_Type
(Ltype
);
2104 if not Is_Enumeration_Type
(Btype
)
2105 or else No
(Enum_Pos_To_Rep
(Btype
))
2111 Make_Defining_Identifier
(Loc
,
2112 Chars
=> New_External_Name
(Chars
(Loop_Id
), 'P'));
2114 Lo
:= Type_Low_Bound
(Ltype
);
2115 Hi
:= Type_High_Bound
(Ltype
);
2118 Make_Loop_Statement
(Loc
,
2119 Identifier
=> Identifier
(N
),
2122 Make_Iteration_Scheme
(Loc
,
2123 Loop_Parameter_Specification
=>
2124 Make_Loop_Parameter_Specification
(Loc
,
2125 Defining_Identifier
=> New_Id
,
2126 Reverse_Present
=> Reverse_Present
(LPS
),
2128 Discrete_Subtype_Definition
=>
2129 Make_Subtype_Indication
(Loc
,
2132 New_Reference_To
(Standard_Natural
, Loc
),
2135 Make_Range_Constraint
(Loc
,
2140 Make_Attribute_Reference
(Loc
,
2142 New_Reference_To
(Btype
, Loc
),
2144 Attribute_Name
=> Name_Pos
,
2146 Expressions
=> New_List
(
2148 (Type_Low_Bound
(Ltype
)))),
2151 Make_Attribute_Reference
(Loc
,
2153 New_Reference_To
(Btype
, Loc
),
2155 Attribute_Name
=> Name_Pos
,
2157 Expressions
=> New_List
(
2159 (Type_High_Bound
(Ltype
))))))))),
2161 Statements
=> New_List
(
2162 Make_Block_Statement
(Loc
,
2163 Declarations
=> New_List
(
2164 Make_Object_Declaration
(Loc
,
2165 Defining_Identifier
=> Loop_Id
,
2166 Constant_Present
=> True,
2167 Object_Definition
=> New_Reference_To
(Ltype
, Loc
),
2169 Make_Indexed_Component
(Loc
,
2171 New_Reference_To
(Enum_Pos_To_Rep
(Btype
), Loc
),
2172 Expressions
=> New_List
(
2173 New_Reference_To
(New_Id
, Loc
))))),
2175 Handled_Statement_Sequence
=>
2176 Make_Handled_Sequence_Of_Statements
(Loc
,
2177 Statements
=> Statements
(N
)))),
2179 End_Label
=> End_Label
(N
)));
2184 -- Second case, if we have a while loop with Condition_Actions set,
2185 -- then we change it into a plain loop:
2194 -- <<condition actions>>
2200 and then Present
(Condition_Actions
(Isc
))
2207 Make_Exit_Statement
(Sloc
(Condition
(Isc
)),
2209 Make_Op_Not
(Sloc
(Condition
(Isc
)),
2210 Right_Opnd
=> Condition
(Isc
)));
2212 Prepend
(ES
, Statements
(N
));
2213 Insert_List_Before
(ES
, Condition_Actions
(Isc
));
2215 -- This is not an implicit loop, since it is generated in
2216 -- response to the loop statement being processed. If this
2217 -- is itself implicit, the restriction has already been
2218 -- checked. If not, it is an explicit loop.
2221 Make_Loop_Statement
(Sloc
(N
),
2222 Identifier
=> Identifier
(N
),
2223 Statements
=> Statements
(N
),
2224 End_Label
=> End_Label
(N
)));
2229 end Expand_N_Loop_Statement
;
2231 -------------------------------
2232 -- Expand_N_Return_Statement --
2233 -------------------------------
2235 procedure Expand_N_Return_Statement
(N
: Node_Id
) is
2236 Loc
: constant Source_Ptr
:= Sloc
(N
);
2237 Exp
: constant Node_Id
:= Expression
(N
);
2241 Scope_Id
: Entity_Id
;
2245 Goto_Stat
: Node_Id
;
2248 Return_Type
: Entity_Id
;
2249 Result_Exp
: Node_Id
;
2250 Result_Id
: Entity_Id
;
2251 Result_Obj
: Node_Id
;
2254 -- Case where returned expression is present
2256 if Present
(Exp
) then
2258 -- Always normalize C/Fortran boolean result. This is not always
2259 -- necessary, but it seems a good idea to minimize the passing
2260 -- around of non-normalized values, and in any case this handles
2261 -- the processing of barrier functions for protected types, which
2262 -- turn the condition into a return statement.
2264 Exptyp
:= Etype
(Exp
);
2266 if Is_Boolean_Type
(Exptyp
)
2267 and then Nonzero_Is_True
(Exptyp
)
2269 Adjust_Condition
(Exp
);
2270 Adjust_Result_Type
(Exp
, Exptyp
);
2273 -- Do validity check if enabled for returns
2275 if Validity_Checks_On
2276 and then Validity_Check_Returns
2282 -- Find relevant enclosing scope from which return is returning
2284 Cur_Idx
:= Scope_Stack
.Last
;
2286 Scope_Id
:= Scope_Stack
.Table
(Cur_Idx
).Entity
;
2288 if Ekind
(Scope_Id
) /= E_Block
2289 and then Ekind
(Scope_Id
) /= E_Loop
2294 Cur_Idx
:= Cur_Idx
- 1;
2295 pragma Assert
(Cur_Idx
>= 0);
2300 Kind
:= Ekind
(Scope_Id
);
2302 -- If it is a return from procedures do no extra steps.
2304 if Kind
= E_Procedure
or else Kind
= E_Generic_Procedure
then
2308 pragma Assert
(Is_Entry
(Scope_Id
));
2310 -- Look at the enclosing block to see whether the return is from
2311 -- an accept statement or an entry body.
2313 for J
in reverse 0 .. Cur_Idx
loop
2314 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
2315 exit when Is_Concurrent_Type
(Scope_Id
);
2318 -- If it is a return from accept statement it should be expanded
2319 -- as a call to RTS Complete_Rendezvous and a goto to the end of
2322 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
2323 -- Expand_N_Accept_Alternative in exp_ch9.adb)
2325 if Is_Task_Type
(Scope_Id
) then
2327 Call
:= (Make_Procedure_Call_Statement
(Loc
,
2328 Name
=> New_Reference_To
2329 (RTE
(RE_Complete_Rendezvous
), Loc
)));
2330 Insert_Before
(N
, Call
);
2331 -- why not insert actions here???
2334 Acc_Stat
:= Parent
(N
);
2335 while Nkind
(Acc_Stat
) /= N_Accept_Statement
loop
2336 Acc_Stat
:= Parent
(Acc_Stat
);
2339 Lab_Node
:= Last
(Statements
2340 (Handled_Statement_Sequence
(Acc_Stat
)));
2342 Goto_Stat
:= Make_Goto_Statement
(Loc
,
2343 Name
=> New_Occurrence_Of
2344 (Entity
(Identifier
(Lab_Node
)), Loc
));
2346 Set_Analyzed
(Goto_Stat
);
2348 Rewrite
(N
, Goto_Stat
);
2351 -- If it is a return from an entry body, put a Complete_Entry_Body
2352 -- call in front of the return.
2354 elsif Is_Protected_Type
(Scope_Id
) then
2357 Make_Procedure_Call_Statement
(Loc
,
2358 Name
=> New_Reference_To
2359 (RTE
(RE_Complete_Entry_Body
), Loc
),
2360 Parameter_Associations
=> New_List
2361 (Make_Attribute_Reference
(Loc
,
2365 (Corresponding_Body
(Parent
(Scope_Id
))),
2367 Attribute_Name
=> Name_Unchecked_Access
)));
2369 Insert_Before
(N
, Call
);
2378 Return_Type
:= Etype
(Scope_Id
);
2379 Utyp
:= Underlying_Type
(Return_Type
);
2381 -- Check the result expression of a scalar function against
2382 -- the subtype of the function by inserting a conversion.
2383 -- This conversion must eventually be performed for other
2384 -- classes of types, but for now it's only done for scalars.
2387 if Is_Scalar_Type
(T
) then
2388 Rewrite
(Exp
, Convert_To
(Return_Type
, Exp
));
2392 -- Implement the rules of 6.5(8-10), which require a tag check in
2393 -- the case of a limited tagged return type, and tag reassignment
2394 -- for nonlimited tagged results. These actions are needed when
2395 -- the return type is a specific tagged type and the result
2396 -- expression is a conversion or a formal parameter, because in
2397 -- that case the tag of the expression might differ from the tag
2398 -- of the specific result type.
2400 if Is_Tagged_Type
(Utyp
)
2401 and then not Is_Class_Wide_Type
(Utyp
)
2402 and then (Nkind
(Exp
) = N_Type_Conversion
2403 or else Nkind
(Exp
) = N_Unchecked_Type_Conversion
2404 or else (Is_Entity_Name
(Exp
)
2405 and then Ekind
(Entity
(Exp
)) in Formal_Kind
))
2407 -- When the return type is limited, perform a check that the
2408 -- tag of the result is the same as the tag of the return type.
2410 if Is_Limited_Type
(Return_Type
) then
2412 Make_Raise_Constraint_Error
(Loc
,
2416 Make_Selected_Component
(Loc
,
2417 Prefix
=> Duplicate_Subexpr
(Exp
),
2419 New_Reference_To
(Tag_Component
(Utyp
), Loc
)),
2421 Unchecked_Convert_To
(RTE
(RE_Tag
),
2423 (Access_Disp_Table
(Base_Type
(Utyp
)), Loc
))),
2424 Reason
=> CE_Tag_Check_Failed
));
2426 -- If the result type is a specific nonlimited tagged type,
2427 -- then we have to ensure that the tag of the result is that
2428 -- of the result type. This is handled by making a copy of the
2429 -- expression in the case where it might have a different tag,
2430 -- namely when the expression is a conversion or a formal
2431 -- parameter. We create a new object of the result type and
2432 -- initialize it from the expression, which will implicitly
2433 -- force the tag to be set appropriately.
2437 Make_Defining_Identifier
(Loc
, New_Internal_Name
('R'));
2438 Result_Exp
:= New_Reference_To
(Result_Id
, Loc
);
2441 Make_Object_Declaration
(Loc
,
2442 Defining_Identifier
=> Result_Id
,
2443 Object_Definition
=> New_Reference_To
(Return_Type
, Loc
),
2444 Constant_Present
=> True,
2445 Expression
=> Relocate_Node
(Exp
));
2447 Set_Assignment_OK
(Result_Obj
);
2448 Insert_Action
(Exp
, Result_Obj
);
2450 Rewrite
(Exp
, Result_Exp
);
2451 Analyze_And_Resolve
(Exp
, Return_Type
);
2455 -- Deal with returning variable length objects and controlled types
2457 -- Nothing to do if we are returning by reference, or this is not
2458 -- a type that requires special processing (indicated by the fact
2459 -- that it requires a cleanup scope for the secondary stack case)
2461 if Is_Return_By_Reference_Type
(T
)
2462 or else not Requires_Transient_Scope
(Return_Type
)
2466 -- Case of secondary stack not used
2468 elsif Function_Returns_With_DSP
(Scope_Id
) then
2470 -- Here what we need to do is to always return by reference, since
2471 -- we will return with the stack pointer depressed. We may need to
2472 -- do a copy to a local temporary before doing this return.
2474 No_Secondary_Stack_Case
: declare
2475 Local_Copy_Required
: Boolean := False;
2476 -- Set to True if a local copy is required
2478 Copy_Ent
: Entity_Id
;
2479 -- Used for the target entity if a copy is required
2482 -- Declaration used to create copy if needed
2484 procedure Test_Copy_Required
(Expr
: Node_Id
);
2485 -- Determines if Expr represents a return value for which a
2486 -- copy is required. More specifically, a copy is not required
2487 -- if Expr represents an object or component of an object that
2488 -- is either in the local subprogram frame, or is constant.
2489 -- If a copy is required, then Local_Copy_Required is set True.
2491 ------------------------
2492 -- Test_Copy_Required --
2493 ------------------------
2495 procedure Test_Copy_Required
(Expr
: Node_Id
) is
2499 -- If component, test prefix (object containing component)
2501 if Nkind
(Expr
) = N_Indexed_Component
2503 Nkind
(Expr
) = N_Selected_Component
2505 Test_Copy_Required
(Prefix
(Expr
));
2508 -- See if we have an entity name
2510 elsif Is_Entity_Name
(Expr
) then
2511 Ent
:= Entity
(Expr
);
2513 -- Constant entity is always OK, no copy required
2515 if Ekind
(Ent
) = E_Constant
then
2518 -- No copy required for local variable
2520 elsif Ekind
(Ent
) = E_Variable
2521 and then Scope
(Ent
) = Current_Subprogram
2527 -- All other cases require a copy
2529 Local_Copy_Required
:= True;
2530 end Test_Copy_Required
;
2532 -- Start of processing for No_Secondary_Stack_Case
2535 -- No copy needed if result is from a function call for the
2536 -- same type with the same constrainedness (is the latter a
2537 -- necessary check, or could gigi produce the bounds ???).
2538 -- In this case the result is already being returned by
2539 -- reference with the stack pointer depressed.
2541 if Requires_Transient_Scope
(T
)
2542 and then Is_Constrained
(T
) = Is_Constrained
(Return_Type
)
2543 and then (Nkind
(Exp
) = N_Function_Call
2545 Nkind
(Original_Node
(Exp
)) = N_Function_Call
)
2549 -- We always need a local copy for a controlled type, since
2550 -- we are required to finalize the local value before return.
2551 -- The copy will automatically include the required finalize.
2552 -- Moreover, gigi cannot make this copy, since we need special
2553 -- processing to ensure proper behavior for finalization.
2555 -- Note: the reason we are returning with a depressed stack
2556 -- pointer in the controlled case (even if the type involved
2557 -- is constrained) is that we must make a local copy to deal
2558 -- properly with the requirement that the local result be
2561 elsif Controlled_Type
(Utyp
) then
2563 Make_Defining_Identifier
(Loc
,
2564 Chars
=> New_Internal_Name
('R'));
2566 -- Build declaration to do the copy, and insert it, setting
2567 -- Assignment_OK, because we may be copying a limited type.
2568 -- In addition we set the special flag to inhibit finalize
2569 -- attachment if this is a controlled type (since this attach
2570 -- must be done by the caller, otherwise if we attach it here
2571 -- we will finalize the returned result prematurely).
2574 Make_Object_Declaration
(Loc
,
2575 Defining_Identifier
=> Copy_Ent
,
2576 Object_Definition
=> New_Occurrence_Of
(Return_Type
, Loc
),
2577 Expression
=> Relocate_Node
(Exp
));
2579 Set_Assignment_OK
(Decl
);
2580 Set_Delay_Finalize_Attach
(Decl
);
2581 Insert_Action
(N
, Decl
);
2583 -- Now the actual return uses the copied value
2585 Rewrite
(Exp
, New_Occurrence_Of
(Copy_Ent
, Loc
));
2586 Analyze_And_Resolve
(Exp
, Return_Type
);
2588 -- Since we have made the copy, gigi does not have to, so
2589 -- we set the By_Ref flag to prevent another copy being made.
2593 -- Non-controlled cases
2596 Test_Copy_Required
(Exp
);
2598 -- If a local copy is required, then gigi will make the
2599 -- copy, otherwise, we can return the result directly,
2600 -- so set By_Ref to suppress the gigi copy.
2602 if not Local_Copy_Required
then
2606 end No_Secondary_Stack_Case
;
2608 -- Here if secondary stack is used
2611 -- Make sure that no surrounding block will reclaim the
2612 -- secondary-stack on which we are going to put the result.
2613 -- Not only may this introduce secondary stack leaks but worse,
2614 -- if the reclamation is done too early, then the result we are
2615 -- returning may get clobbered. See example in 7417-003.
2618 S
: Entity_Id
:= Current_Scope
;
2621 while Ekind
(S
) = E_Block
or else Ekind
(S
) = E_Loop
loop
2622 Set_Sec_Stack_Needed_For_Return
(S
, True);
2623 S
:= Enclosing_Dynamic_Scope
(S
);
2627 -- Optimize the case where the result is from a function call for
2628 -- the same type with the same constrainedness (is the latter a
2629 -- necessary check, or could gigi produce the bounds ???). In this
2630 -- case either the result is already on the secondary stack, or is
2631 -- already being returned with the stack pointer depressed and no
2632 -- further processing is required except to set the By_Ref flag to
2633 -- ensure that gigi does not attempt an extra unnecessary copy.
2634 -- (actually not just unnecessary but harmfully wrong in the case
2635 -- of a controlled type, where gigi does not know how to do a copy).
2637 if Requires_Transient_Scope
(T
)
2638 and then Is_Constrained
(T
) = Is_Constrained
(Return_Type
)
2639 and then (Nkind
(Exp
) = N_Function_Call
2640 or else Nkind
(Original_Node
(Exp
)) = N_Function_Call
)
2644 -- For controlled types, do the allocation on the sec-stack
2645 -- manually in order to call adjust at the right time
2646 -- type Anon1 is access Return_Type;
2647 -- for Anon1'Storage_pool use ss_pool;
2648 -- Anon2 : anon1 := new Return_Type'(expr);
2649 -- return Anon2.all;
2651 elsif Controlled_Type
(Utyp
) then
2653 Loc
: constant Source_Ptr
:= Sloc
(N
);
2654 Temp
: constant Entity_Id
:=
2655 Make_Defining_Identifier
(Loc
,
2656 Chars
=> New_Internal_Name
('R'));
2657 Acc_Typ
: constant Entity_Id
:=
2658 Make_Defining_Identifier
(Loc
,
2659 Chars
=> New_Internal_Name
('A'));
2660 Alloc_Node
: Node_Id
;
2663 Set_Ekind
(Acc_Typ
, E_Access_Type
);
2665 Set_Associated_Storage_Pool
(Acc_Typ
, RTE
(RE_SS_Pool
));
2668 Make_Allocator
(Loc
,
2670 Make_Qualified_Expression
(Loc
,
2671 Subtype_Mark
=> New_Reference_To
(Etype
(Exp
), Loc
),
2672 Expression
=> Relocate_Node
(Exp
)));
2674 Insert_List_Before_And_Analyze
(N
, New_List
(
2675 Make_Full_Type_Declaration
(Loc
,
2676 Defining_Identifier
=> Acc_Typ
,
2678 Make_Access_To_Object_Definition
(Loc
,
2679 Subtype_Indication
=>
2680 New_Reference_To
(Return_Type
, Loc
))),
2682 Make_Object_Declaration
(Loc
,
2683 Defining_Identifier
=> Temp
,
2684 Object_Definition
=> New_Reference_To
(Acc_Typ
, Loc
),
2685 Expression
=> Alloc_Node
)));
2688 Make_Explicit_Dereference
(Loc
,
2689 Prefix
=> New_Reference_To
(Temp
, Loc
)));
2691 Analyze_And_Resolve
(Exp
, Return_Type
);
2694 -- Otherwise use the gigi mechanism to allocate result on the
2698 Set_Storage_Pool
(N
, RTE
(RE_SS_Pool
));
2700 -- If we are generating code for the Java VM do not use
2701 -- SS_Allocate since everything is heap-allocated anyway.
2704 Set_Procedure_To_Call
(N
, RTE
(RE_SS_Allocate
));
2708 end Expand_N_Return_Statement
;
2710 ------------------------------
2711 -- Make_Tag_Ctrl_Assignment --
2712 ------------------------------
2714 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
is
2715 Loc
: constant Source_Ptr
:= Sloc
(N
);
2716 L
: constant Node_Id
:= Name
(N
);
2717 T
: constant Entity_Id
:= Underlying_Type
(Etype
(L
));
2719 Ctrl_Act
: constant Boolean := Controlled_Type
(T
)
2720 and then not No_Ctrl_Actions
(N
);
2722 Save_Tag
: constant Boolean := Is_Tagged_Type
(T
)
2723 and then not No_Ctrl_Actions
(N
)
2724 and then not Java_VM
;
2725 -- Tags are not saved and restored when Java_VM because JVM tags
2726 -- are represented implicitly in objects.
2729 Tag_Tmp
: Entity_Id
;
2730 Prev_Tmp
: Entity_Id
;
2731 Next_Tmp
: Entity_Id
;
2737 -- Finalize the target of the assignment when controlled.
2738 -- We have two exceptions here:
2740 -- 1. If we are in an init_proc since it is an initialization
2741 -- more than an assignment
2743 -- 2. If the left-hand side is a temporary that was not initialized
2744 -- (or the parent part of a temporary since it is the case in
2745 -- extension aggregates). Such a temporary does not come from
2746 -- source. We must examine the original node for the prefix, because
2747 -- it may be a component of an entry formal, in which case it has
2748 -- been rewritten and does not appear to come from source either.
2752 if not Ctrl_Act
then
2755 -- The left hand side is an uninitialized temporary
2757 elsif Nkind
(L
) = N_Type_Conversion
2758 and then Is_Entity_Name
(Expression
(L
))
2759 and then No_Initialization
(Parent
(Entity
(Expression
(L
))))
2763 Append_List_To
(Res
,
2765 Ref
=> Duplicate_Subexpr
(L
),
2767 With_Detach
=> New_Reference_To
(Standard_False
, Loc
)));
2770 Next_Tmp
:= Make_Defining_Identifier
(Loc
, New_Internal_Name
('C'));
2772 -- Save the Tag in a local variable Tag_Tmp
2776 Make_Defining_Identifier
(Loc
, New_Internal_Name
('A'));
2779 Make_Object_Declaration
(Loc
,
2780 Defining_Identifier
=> Tag_Tmp
,
2781 Object_Definition
=> New_Reference_To
(RTE
(RE_Tag
), Loc
),
2783 Make_Selected_Component
(Loc
,
2784 Prefix
=> Duplicate_Subexpr
(L
),
2785 Selector_Name
=> New_Reference_To
(Tag_Component
(T
), Loc
))));
2787 -- Otherwise Tag_Tmp not used
2793 -- Save the Finalization Pointers in local variables Prev_Tmp and
2794 -- Next_Tmp. For objects with Has_Controlled_Component set, these
2795 -- pointers are in the Record_Controller
2798 Ctrl_Ref
:= Duplicate_Subexpr
(L
);
2800 if Has_Controlled_Component
(T
) then
2802 Make_Selected_Component
(Loc
,
2805 New_Reference_To
(Controller_Component
(T
), Loc
));
2808 Prev_Tmp
:= Make_Defining_Identifier
(Loc
, New_Internal_Name
('B'));
2811 Make_Object_Declaration
(Loc
,
2812 Defining_Identifier
=> Prev_Tmp
,
2814 Object_Definition
=>
2815 New_Reference_To
(RTE
(RE_Finalizable_Ptr
), Loc
),
2818 Make_Selected_Component
(Loc
,
2820 Unchecked_Convert_To
(RTE
(RE_Finalizable
), Ctrl_Ref
),
2821 Selector_Name
=> Make_Identifier
(Loc
, Name_Prev
))));
2823 Next_Tmp
:= Make_Defining_Identifier
(Loc
, New_Internal_Name
('C'));
2826 Make_Object_Declaration
(Loc
,
2827 Defining_Identifier
=> Next_Tmp
,
2829 Object_Definition
=>
2830 New_Reference_To
(RTE
(RE_Finalizable_Ptr
), Loc
),
2833 Make_Selected_Component
(Loc
,
2835 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
2836 New_Copy_Tree
(Ctrl_Ref
)),
2837 Selector_Name
=> Make_Identifier
(Loc
, Name_Next
))));
2839 -- If not controlled type, then Prev_Tmp and Ctrl_Ref unused
2846 -- Do the Assignment
2848 Append_To
(Res
, Relocate_Node
(N
));
2854 Make_Assignment_Statement
(Loc
,
2856 Make_Selected_Component
(Loc
,
2857 Prefix
=> Duplicate_Subexpr
(L
),
2858 Selector_Name
=> New_Reference_To
(Tag_Component
(T
), Loc
)),
2859 Expression
=> New_Reference_To
(Tag_Tmp
, Loc
)));
2862 -- Restore the finalization pointers
2866 Make_Assignment_Statement
(Loc
,
2868 Make_Selected_Component
(Loc
,
2870 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
2871 New_Copy_Tree
(Ctrl_Ref
)),
2872 Selector_Name
=> Make_Identifier
(Loc
, Name_Prev
)),
2873 Expression
=> New_Reference_To
(Prev_Tmp
, Loc
)));
2876 Make_Assignment_Statement
(Loc
,
2878 Make_Selected_Component
(Loc
,
2880 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
2881 New_Copy_Tree
(Ctrl_Ref
)),
2882 Selector_Name
=> Make_Identifier
(Loc
, Name_Next
)),
2883 Expression
=> New_Reference_To
(Next_Tmp
, Loc
)));
2886 -- Adjust the target after the assignment when controlled. (not in
2887 -- the init_proc since it is an initialization more than an
2891 Append_List_To
(Res
,
2893 Ref
=> Duplicate_Subexpr
(L
),
2895 Flist_Ref
=> New_Reference_To
(RTE
(RE_Global_Final_List
), Loc
),
2896 With_Attach
=> Make_Integer_Literal
(Loc
, 0)));
2900 end Make_Tag_Ctrl_Assignment
;