1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2005, 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_Ch8
; use Sem_Ch8
;
49 with Sem_Ch13
; use Sem_Ch13
;
50 with Sem_Eval
; use Sem_Eval
;
51 with Sem_Res
; use Sem_Res
;
52 with Sem_Util
; use Sem_Util
;
53 with Snames
; use Snames
;
54 with Stand
; use Stand
;
55 with Stringt
; use Stringt
;
56 with Tbuild
; use Tbuild
;
57 with Ttypes
; use Ttypes
;
58 with Uintp
; use Uintp
;
59 with Validsw
; use Validsw
;
61 package body Exp_Ch5
is
63 function Change_Of_Representation
(N
: Node_Id
) return Boolean;
64 -- Determine if the right hand side of the assignment N is a type
65 -- conversion which requires a change of representation. Called
66 -- only for the array and record cases.
68 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
);
69 -- N is an assignment which assigns an array value. This routine process
70 -- the various special cases and checks required for such assignments,
71 -- including change of representation. Rhs is normally simply the right
72 -- hand side of the assignment, except that if the right hand side is
73 -- a type conversion or a qualified expression, then the Rhs is the
74 -- actual expression inside any such type conversions or qualifications.
76 function Expand_Assign_Array_Loop
83 Rev
: Boolean) return Node_Id
;
84 -- N is an assignment statement which assigns an array value. This routine
85 -- expands the assignment into a loop (or nested loops for the case of a
86 -- multi-dimensional array) to do the assignment component by component.
87 -- Larray and Rarray are the entities of the actual arrays on the left
88 -- hand and right hand sides. L_Type and R_Type are the types of these
89 -- arrays (which may not be the same, due to either sliding, or to a
90 -- change of representation case). Ndim is the number of dimensions and
91 -- the parameter Rev indicates if the loops run normally (Rev = False),
92 -- or reversed (Rev = True). The value returned is the constructed
93 -- loop statement. Auxiliary declarations are inserted before node N
94 -- using the standard Insert_Actions mechanism.
96 procedure Expand_Assign_Record
(N
: Node_Id
);
97 -- N is an assignment of a non-tagged record value. This routine handles
98 -- the case where the assignment must be made component by component,
99 -- either because the target is not byte aligned, or there is a change
100 -- of representation.
102 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
;
103 -- Generate the necessary code for controlled and tagged assignment,
104 -- that is to say, finalization of the target before, adjustement of
105 -- the target after and save and restore of the tag and finalization
106 -- pointers which are not 'part of the value' and must not be changed
107 -- upon assignment. N is the original Assignment node.
109 function Possible_Bit_Aligned_Component
(N
: Node_Id
) return Boolean;
110 -- This function is used in processing the assignment of a record or
111 -- indexed component. The argument N is either the left hand or right
112 -- hand side of an assignment, and this function determines if there
113 -- is a record component reference where the record may be bit aligned
114 -- in a manner that causes trouble for the back end (see description
115 -- of Exp_Util.Component_May_Be_Bit_Aligned for further details).
117 ------------------------------
118 -- Change_Of_Representation --
119 ------------------------------
121 function Change_Of_Representation
(N
: Node_Id
) return Boolean is
122 Rhs
: constant Node_Id
:= Expression
(N
);
125 Nkind
(Rhs
) = N_Type_Conversion
127 not Same_Representation
(Etype
(Rhs
), Etype
(Expression
(Rhs
)));
128 end Change_Of_Representation
;
130 -------------------------
131 -- Expand_Assign_Array --
132 -------------------------
134 -- There are two issues here. First, do we let Gigi do a block move, or
135 -- do we expand out into a loop? Second, we need to set the two flags
136 -- Forwards_OK and Backwards_OK which show whether the block move (or
137 -- corresponding loops) can be legitimately done in a forwards (low to
138 -- high) or backwards (high to low) manner.
140 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
) is
141 Loc
: constant Source_Ptr
:= Sloc
(N
);
143 Lhs
: constant Node_Id
:= Name
(N
);
145 Act_Lhs
: constant Node_Id
:= Get_Referenced_Object
(Lhs
);
146 Act_Rhs
: Node_Id
:= Get_Referenced_Object
(Rhs
);
148 L_Type
: constant Entity_Id
:=
149 Underlying_Type
(Get_Actual_Subtype
(Act_Lhs
));
150 R_Type
: Entity_Id
:=
151 Underlying_Type
(Get_Actual_Subtype
(Act_Rhs
));
153 L_Slice
: constant Boolean := Nkind
(Act_Lhs
) = N_Slice
;
154 R_Slice
: constant Boolean := Nkind
(Act_Rhs
) = N_Slice
;
156 Crep
: constant Boolean := Change_Of_Representation
(N
);
161 Ndim
: constant Pos
:= Number_Dimensions
(L_Type
);
163 Loop_Required
: Boolean := False;
164 -- This switch is set to True if the array move must be done using
165 -- an explicit front end generated loop.
167 procedure Apply_Dereference
(Arg
: in out Node_Id
);
168 -- If the argument is an access to an array, and the assignment is
169 -- converted into a procedure call, apply explicit dereference.
171 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean;
172 -- Test if Exp is a reference to an array whose declaration has
173 -- an address clause, or it is a slice of such an array.
175 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean;
176 -- Test if Exp is a reference to an array which is either a formal
177 -- parameter or a slice of a formal parameter. These are the cases
178 -- where hidden aliasing can occur.
180 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean;
181 -- Determine if Exp is a reference to an array variable which is other
182 -- than an object defined in the current scope, or a slice of such
183 -- an object. Such objects can be aliased to parameters (unlike local
184 -- array references).
186 -----------------------
187 -- Apply_Dereference --
188 -----------------------
190 procedure Apply_Dereference
(Arg
: in out Node_Id
) is
191 Typ
: constant Entity_Id
:= Etype
(Arg
);
193 if Is_Access_Type
(Typ
) then
194 Rewrite
(Arg
, Make_Explicit_Dereference
(Loc
,
195 Prefix
=> Relocate_Node
(Arg
)));
196 Analyze_And_Resolve
(Arg
, Designated_Type
(Typ
));
198 end Apply_Dereference
;
200 ------------------------
201 -- Has_Address_Clause --
202 ------------------------
204 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean is
207 (Is_Entity_Name
(Exp
) and then
208 Present
(Address_Clause
(Entity
(Exp
))))
210 (Nkind
(Exp
) = N_Slice
and then Has_Address_Clause
(Prefix
(Exp
)));
211 end Has_Address_Clause
;
213 ---------------------
214 -- Is_Formal_Array --
215 ---------------------
217 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean is
220 (Is_Entity_Name
(Exp
) and then Is_Formal
(Entity
(Exp
)))
222 (Nkind
(Exp
) = N_Slice
and then Is_Formal_Array
(Prefix
(Exp
)));
225 ------------------------
226 -- Is_Non_Local_Array --
227 ------------------------
229 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean is
231 return (Is_Entity_Name
(Exp
)
232 and then Scope
(Entity
(Exp
)) /= Current_Scope
)
233 or else (Nkind
(Exp
) = N_Slice
234 and then Is_Non_Local_Array
(Prefix
(Exp
)));
235 end Is_Non_Local_Array
;
237 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
239 Lhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Lhs
);
240 Rhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Rhs
);
242 Lhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Lhs
);
243 Rhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Rhs
);
245 -- Start of processing for Expand_Assign_Array
248 -- Deal with length check, note that the length check is done with
249 -- respect to the right hand side as given, not a possible underlying
250 -- renamed object, since this would generate incorrect extra checks.
252 Apply_Length_Check
(Rhs
, L_Type
);
254 -- We start by assuming that the move can be done in either
255 -- direction, i.e. that the two sides are completely disjoint.
257 Set_Forwards_OK
(N
, True);
258 Set_Backwards_OK
(N
, True);
260 -- Normally it is only the slice case that can lead to overlap,
261 -- and explicit checks for slices are made below. But there is
262 -- one case where the slice can be implicit and invisible to us
263 -- and that is the case where we have a one dimensional array,
264 -- and either both operands are parameters, or one is a parameter
265 -- and the other is a global variable. In this case the parameter
266 -- could be a slice that overlaps with the other parameter.
268 -- Check for the case of slices requiring an explicit loop. Normally
269 -- it is only the explicit slice cases that bother us, but in the
270 -- case of one dimensional arrays, parameters can be slices that
271 -- are passed by reference, so we can have aliasing for assignments
272 -- from one parameter to another, or assignments between parameters
273 -- and nonlocal variables. However, if the array subtype is a
274 -- constrained first subtype in the parameter case, then we don't
275 -- have to worry about overlap, since slice assignments aren't
276 -- possible (other than for a slice denoting the whole array).
278 -- Note: overlap is never possible if there is a change of
279 -- representation, so we can exclude this case.
284 ((Lhs_Formal
and Rhs_Formal
)
286 (Lhs_Formal
and Rhs_Non_Local_Var
)
288 (Rhs_Formal
and Lhs_Non_Local_Var
))
290 (not Is_Constrained
(Etype
(Lhs
))
291 or else not Is_First_Subtype
(Etype
(Lhs
)))
293 -- In the case of compiling for the Java Virtual Machine,
294 -- slices are always passed by making a copy, so we don't
295 -- have to worry about overlap. We also want to prevent
296 -- generation of "<" comparisons for array addresses,
297 -- since that's a meaningless operation on the JVM.
301 Set_Forwards_OK
(N
, False);
302 Set_Backwards_OK
(N
, False);
304 -- Note: the bit-packed case is not worrisome here, since if
305 -- we have a slice passed as a parameter, it is always aligned
306 -- on a byte boundary, and if there are no explicit slices, the
307 -- assignment can be performed directly.
310 -- We certainly must use a loop for change of representation
311 -- and also we use the operand of the conversion on the right
312 -- hand side as the effective right hand side (the component
313 -- types must match in this situation).
316 Act_Rhs
:= Get_Referenced_Object
(Rhs
);
317 R_Type
:= Get_Actual_Subtype
(Act_Rhs
);
318 Loop_Required
:= True;
320 -- We require a loop if the left side is possibly bit unaligned
322 elsif Possible_Bit_Aligned_Component
(Lhs
)
324 Possible_Bit_Aligned_Component
(Rhs
)
326 Loop_Required
:= True;
328 -- Arrays with controlled components are expanded into a loop
329 -- to force calls to adjust at the component level.
331 elsif Has_Controlled_Component
(L_Type
) then
332 Loop_Required
:= True;
334 -- If object is atomic, we cannot tolerate a loop
336 elsif Is_Atomic_Object
(Act_Lhs
)
338 Is_Atomic_Object
(Act_Rhs
)
342 -- Loop is required if we have atomic components since we have to
343 -- be sure to do any accesses on an element by element basis.
345 elsif Has_Atomic_Components
(L_Type
)
346 or else Has_Atomic_Components
(R_Type
)
347 or else Is_Atomic
(Component_Type
(L_Type
))
348 or else Is_Atomic
(Component_Type
(R_Type
))
350 Loop_Required
:= True;
352 -- Case where no slice is involved
354 elsif not L_Slice
and not R_Slice
then
356 -- The following code deals with the case of unconstrained bit
357 -- packed arrays. The problem is that the template for such
358 -- arrays contains the bounds of the actual source level array,
360 -- But the copy of an entire array requires the bounds of the
361 -- underlying array. It would be nice if the back end could take
362 -- care of this, but right now it does not know how, so if we
363 -- have such a type, then we expand out into a loop, which is
364 -- inefficient but works correctly. If we don't do this, we
365 -- get the wrong length computed for the array to be moved.
366 -- The two cases we need to worry about are:
368 -- Explicit deference of an unconstrained packed array type as
369 -- in the following example:
372 -- type BITS is array(INTEGER range <>) of BOOLEAN;
373 -- pragma PACK(BITS);
374 -- type A is access BITS;
377 -- P1 := new BITS (1 .. 65_535);
378 -- P2 := new BITS (1 .. 65_535);
382 -- A formal parameter reference with an unconstrained bit
383 -- array type is the other case we need to worry about (here
384 -- we assume the same BITS type declared above:
386 -- procedure Write_All (File : out BITS; Contents : in BITS);
388 -- File.Storage := Contents;
391 -- We expand to a loop in either of these two cases
393 -- Question for future thought. Another potentially more efficient
394 -- approach would be to create the actual subtype, and then do an
395 -- unchecked conversion to this actual subtype ???
397 Check_Unconstrained_Bit_Packed_Array
: declare
399 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean;
400 -- Function to perform required test for the first case,
401 -- above (dereference of an unconstrained bit packed array)
403 -----------------------
404 -- Is_UBPA_Reference --
405 -----------------------
407 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean is
408 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Opnd
));
410 Des_Type
: Entity_Id
;
413 if Present
(Packed_Array_Type
(Typ
))
414 and then Is_Array_Type
(Packed_Array_Type
(Typ
))
415 and then not Is_Constrained
(Packed_Array_Type
(Typ
))
419 elsif Nkind
(Opnd
) = N_Explicit_Dereference
then
420 P_Type
:= Underlying_Type
(Etype
(Prefix
(Opnd
)));
422 if not Is_Access_Type
(P_Type
) then
426 Des_Type
:= Designated_Type
(P_Type
);
428 Is_Bit_Packed_Array
(Des_Type
)
429 and then not Is_Constrained
(Des_Type
);
435 end Is_UBPA_Reference
;
437 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
440 if Is_UBPA_Reference
(Lhs
)
442 Is_UBPA_Reference
(Rhs
)
444 Loop_Required
:= True;
446 -- Here if we do not have the case of a reference to a bit
447 -- packed unconstrained array case. In this case gigi can
448 -- most certainly handle the assignment if a forwards move
451 -- (could it handle the backwards case also???)
453 elsif Forwards_OK
(N
) then
456 end Check_Unconstrained_Bit_Packed_Array
;
458 -- The back end can always handle the assignment if the right side is a
459 -- string literal (note that overlap is definitely impossible in this
460 -- case). If the type is packed, a string literal is always converted
461 -- into aggregate, except in the case of a null slice, for which no
462 -- aggregate can be written. In that case, rewrite the assignment as a
463 -- null statement, a length check has already been emitted to verify
464 -- that the range of the left-hand side is empty.
466 -- Note that this code is not executed if we had an assignment of
467 -- a string literal to a non-bit aligned component of a record, a
468 -- case which cannot be handled by the backend
470 elsif Nkind
(Rhs
) = N_String_Literal
then
471 if String_Length
(Strval
(Rhs
)) = 0
472 and then Is_Bit_Packed_Array
(L_Type
)
474 Rewrite
(N
, Make_Null_Statement
(Loc
));
480 -- If either operand is bit packed, then we need a loop, since we
481 -- can't be sure that the slice is byte aligned. Similarly, if either
482 -- operand is a possibly unaligned slice, then we need a loop (since
483 -- the back end cannot handle unaligned slices).
485 elsif Is_Bit_Packed_Array
(L_Type
)
486 or else Is_Bit_Packed_Array
(R_Type
)
487 or else Is_Possibly_Unaligned_Slice
(Lhs
)
488 or else Is_Possibly_Unaligned_Slice
(Rhs
)
490 Loop_Required
:= True;
492 -- If we are not bit-packed, and we have only one slice, then no
493 -- overlap is possible except in the parameter case, so we can let
494 -- the back end handle things.
496 elsif not (L_Slice
and R_Slice
) then
497 if Forwards_OK
(N
) then
502 -- If the right-hand side is a string literal, introduce a temporary
503 -- for it, for use in the generated loop that will follow.
505 if Nkind
(Rhs
) = N_String_Literal
then
507 Temp
: constant Entity_Id
:=
508 Make_Defining_Identifier
(Loc
, Name_T
);
513 Make_Object_Declaration
(Loc
,
514 Defining_Identifier
=> Temp
,
515 Object_Definition
=> New_Occurrence_Of
(L_Type
, Loc
),
516 Expression
=> Relocate_Node
(Rhs
));
518 Insert_Action
(N
, Decl
);
519 Rewrite
(Rhs
, New_Occurrence_Of
(Temp
, Loc
));
520 R_Type
:= Etype
(Temp
);
524 -- Come here to complete the analysis
526 -- Loop_Required: Set to True if we know that a loop is required
527 -- regardless of overlap considerations.
529 -- Forwards_OK: Set to False if we already know that a forwards
530 -- move is not safe, else set to True.
532 -- Backwards_OK: Set to False if we already know that a backwards
533 -- move is not safe, else set to True
535 -- Our task at this stage is to complete the overlap analysis, which
536 -- can result in possibly setting Forwards_OK or Backwards_OK to
537 -- False, and then generating the final code, either by deciding
538 -- that it is OK after all to let Gigi handle it, or by generating
539 -- appropriate code in the front end.
542 L_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(L_Type
));
543 R_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(R_Type
));
545 Left_Lo
: constant Node_Id
:= Type_Low_Bound
(L_Index_Typ
);
546 Left_Hi
: constant Node_Id
:= Type_High_Bound
(L_Index_Typ
);
547 Right_Lo
: constant Node_Id
:= Type_Low_Bound
(R_Index_Typ
);
548 Right_Hi
: constant Node_Id
:= Type_High_Bound
(R_Index_Typ
);
550 Act_L_Array
: Node_Id
;
551 Act_R_Array
: Node_Id
;
557 Cresult
: Compare_Result
;
560 -- Get the expressions for the arrays. If we are dealing with a
561 -- private type, then convert to the underlying type. We can do
562 -- direct assignments to an array that is a private type, but
563 -- we cannot assign to elements of the array without this extra
564 -- unchecked conversion.
566 if Nkind
(Act_Lhs
) = N_Slice
then
567 Larray
:= Prefix
(Act_Lhs
);
571 if Is_Private_Type
(Etype
(Larray
)) then
574 (Underlying_Type
(Etype
(Larray
)), Larray
);
578 if Nkind
(Act_Rhs
) = N_Slice
then
579 Rarray
:= Prefix
(Act_Rhs
);
583 if Is_Private_Type
(Etype
(Rarray
)) then
586 (Underlying_Type
(Etype
(Rarray
)), Rarray
);
590 -- If both sides are slices, we must figure out whether
591 -- it is safe to do the move in one direction or the other
592 -- It is always safe if there is a change of representation
593 -- since obviously two arrays with different representations
594 -- cannot possibly overlap.
596 if (not Crep
) and L_Slice
and R_Slice
then
597 Act_L_Array
:= Get_Referenced_Object
(Prefix
(Act_Lhs
));
598 Act_R_Array
:= Get_Referenced_Object
(Prefix
(Act_Rhs
));
600 -- If both left and right hand arrays are entity names, and
601 -- refer to different entities, then we know that the move
602 -- is safe (the two storage areas are completely disjoint).
604 if Is_Entity_Name
(Act_L_Array
)
605 and then Is_Entity_Name
(Act_R_Array
)
606 and then Entity
(Act_L_Array
) /= Entity
(Act_R_Array
)
610 -- Otherwise, we assume the worst, which is that the two
611 -- arrays are the same array. There is no need to check if
612 -- we know that is the case, because if we don't know it,
613 -- we still have to assume it!
615 -- Generally if the same array is involved, then we have
616 -- an overlapping case. We will have to really assume the
617 -- worst (i.e. set neither of the OK flags) unless we can
618 -- determine the lower or upper bounds at compile time and
622 Cresult
:= Compile_Time_Compare
(Left_Lo
, Right_Lo
);
624 if Cresult
= Unknown
then
625 Cresult
:= Compile_Time_Compare
(Left_Hi
, Right_Hi
);
629 when LT | LE | EQ
=> Set_Backwards_OK
(N
, False);
630 when GT | GE
=> Set_Forwards_OK
(N
, False);
631 when NE | Unknown
=> Set_Backwards_OK
(N
, False);
632 Set_Forwards_OK
(N
, False);
637 -- If after that analysis, Forwards_OK is still True, and
638 -- Loop_Required is False, meaning that we have not discovered
639 -- some non-overlap reason for requiring a loop, then we can
640 -- still let gigi handle it.
642 if not Loop_Required
then
643 if Forwards_OK
(N
) then
647 -- Here is where a memmove would be appropriate ???
651 -- At this stage we have to generate an explicit loop, and
652 -- we have the following cases:
654 -- Forwards_OK = True
656 -- Rnn : right_index := right_index'First;
657 -- for Lnn in left-index loop
658 -- left (Lnn) := right (Rnn);
659 -- Rnn := right_index'Succ (Rnn);
662 -- Note: the above code MUST be analyzed with checks off,
663 -- because otherwise the Succ could overflow. But in any
664 -- case this is more efficient!
666 -- Forwards_OK = False, Backwards_OK = True
668 -- Rnn : right_index := right_index'Last;
669 -- for Lnn in reverse left-index loop
670 -- left (Lnn) := right (Rnn);
671 -- Rnn := right_index'Pred (Rnn);
674 -- Note: the above code MUST be analyzed with checks off,
675 -- because otherwise the Pred could overflow. But in any
676 -- case this is more efficient!
678 -- Forwards_OK = Backwards_OK = False
680 -- This only happens if we have the same array on each side. It is
681 -- possible to create situations using overlays that violate this,
682 -- but we simply do not promise to get this "right" in this case.
684 -- There are two possible subcases. If the No_Implicit_Conditionals
685 -- restriction is set, then we generate the following code:
688 -- T : constant <operand-type> := rhs;
693 -- If implicit conditionals are permitted, then we generate:
695 -- if Left_Lo <= Right_Lo then
696 -- <code for Forwards_OK = True above>
698 -- <code for Backwards_OK = True above>
701 -- Cases where either Forwards_OK or Backwards_OK is true
703 if Forwards_OK
(N
) or else Backwards_OK
(N
) then
704 if Controlled_Type
(Component_Type
(L_Type
))
705 and then Base_Type
(L_Type
) = Base_Type
(R_Type
)
707 and then not No_Ctrl_Actions
(N
)
710 Proc
: constant Entity_Id
:=
711 TSS
(Base_Type
(L_Type
), TSS_Slice_Assign
);
715 Apply_Dereference
(Larray
);
716 Apply_Dereference
(Rarray
);
717 Actuals
:= New_List
(
718 Duplicate_Subexpr
(Larray
, Name_Req
=> True),
719 Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
720 Duplicate_Subexpr
(Left_Lo
, Name_Req
=> True),
721 Duplicate_Subexpr
(Left_Hi
, Name_Req
=> True),
722 Duplicate_Subexpr
(Right_Lo
, Name_Req
=> True),
723 Duplicate_Subexpr
(Right_Hi
, Name_Req
=> True));
727 Boolean_Literals
(not Forwards_OK
(N
)), Loc
));
730 Make_Procedure_Call_Statement
(Loc
,
731 Name
=> New_Reference_To
(Proc
, Loc
),
732 Parameter_Associations
=> Actuals
));
737 Expand_Assign_Array_Loop
738 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
739 Rev
=> not Forwards_OK
(N
)));
742 -- Case of both are false with No_Implicit_Conditionals
744 elsif Restriction_Active
(No_Implicit_Conditionals
) then
746 T
: constant Entity_Id
:=
747 Make_Defining_Identifier
(Loc
, Chars
=> Name_T
);
751 Make_Block_Statement
(Loc
,
752 Declarations
=> New_List
(
753 Make_Object_Declaration
(Loc
,
754 Defining_Identifier
=> T
,
755 Constant_Present
=> True,
757 New_Occurrence_Of
(Etype
(Rhs
), Loc
),
758 Expression
=> Relocate_Node
(Rhs
))),
760 Handled_Statement_Sequence
=>
761 Make_Handled_Sequence_Of_Statements
(Loc
,
762 Statements
=> New_List
(
763 Make_Assignment_Statement
(Loc
,
764 Name
=> Relocate_Node
(Lhs
),
765 Expression
=> New_Occurrence_Of
(T
, Loc
))))));
768 -- Case of both are false with implicit conditionals allowed
771 -- Before we generate this code, we must ensure that the
772 -- left and right side array types are defined. They may
773 -- be itypes, and we cannot let them be defined inside the
774 -- if, since the first use in the then may not be executed.
776 Ensure_Defined
(L_Type
, N
);
777 Ensure_Defined
(R_Type
, N
);
779 -- We normally compare addresses to find out which way round
780 -- to do the loop, since this is realiable, and handles the
781 -- cases of parameters, conversions etc. But we can't do that
782 -- in the bit packed case or the Java VM case, because addresses
785 if not Is_Bit_Packed_Array
(L_Type
) and then not Java_VM
then
789 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
790 Make_Attribute_Reference
(Loc
,
792 Make_Indexed_Component
(Loc
,
794 Duplicate_Subexpr_Move_Checks
(Larray
, True),
795 Expressions
=> New_List
(
796 Make_Attribute_Reference
(Loc
,
800 Attribute_Name
=> Name_First
))),
801 Attribute_Name
=> Name_Address
)),
804 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
805 Make_Attribute_Reference
(Loc
,
807 Make_Indexed_Component
(Loc
,
809 Duplicate_Subexpr_Move_Checks
(Rarray
, True),
810 Expressions
=> New_List
(
811 Make_Attribute_Reference
(Loc
,
815 Attribute_Name
=> Name_First
))),
816 Attribute_Name
=> Name_Address
)));
818 -- For the bit packed and Java VM cases we use the bounds.
819 -- That's OK, because we don't have to worry about parameters,
820 -- since they cannot cause overlap. Perhaps we should worry
821 -- about weird slice conversions ???
824 -- Copy the bounds and reset the Analyzed flag, because the
825 -- bounds of the index type itself may be universal, and must
826 -- must be reaanalyzed to acquire the proper type for Gigi.
828 Cleft_Lo
:= New_Copy_Tree
(Left_Lo
);
829 Cright_Lo
:= New_Copy_Tree
(Right_Lo
);
830 Set_Analyzed
(Cleft_Lo
, False);
831 Set_Analyzed
(Cright_Lo
, False);
835 Left_Opnd
=> Cleft_Lo
,
836 Right_Opnd
=> Cright_Lo
);
839 if Controlled_Type
(Component_Type
(L_Type
))
840 and then Base_Type
(L_Type
) = Base_Type
(R_Type
)
842 and then not No_Ctrl_Actions
(N
)
845 -- Call TSS procedure for array assignment, passing the
846 -- the explicit bounds of right and left hand sides.
849 Proc
: constant Node_Id
:=
850 TSS
(Base_Type
(L_Type
), TSS_Slice_Assign
);
854 Apply_Dereference
(Larray
);
855 Apply_Dereference
(Rarray
);
856 Actuals
:= New_List
(
857 Duplicate_Subexpr
(Larray
, Name_Req
=> True),
858 Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
859 Duplicate_Subexpr
(Left_Lo
, Name_Req
=> True),
860 Duplicate_Subexpr
(Left_Hi
, Name_Req
=> True),
861 Duplicate_Subexpr
(Right_Lo
, Name_Req
=> True),
862 Duplicate_Subexpr
(Right_Hi
, Name_Req
=> True));
866 Right_Opnd
=> Condition
));
869 Make_Procedure_Call_Statement
(Loc
,
870 Name
=> New_Reference_To
(Proc
, Loc
),
871 Parameter_Associations
=> Actuals
));
876 Make_Implicit_If_Statement
(N
,
877 Condition
=> Condition
,
879 Then_Statements
=> New_List
(
880 Expand_Assign_Array_Loop
881 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
884 Else_Statements
=> New_List
(
885 Expand_Assign_Array_Loop
886 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
891 Analyze
(N
, Suppress
=> All_Checks
);
895 when RE_Not_Available
=>
897 end Expand_Assign_Array
;
899 ------------------------------
900 -- Expand_Assign_Array_Loop --
901 ------------------------------
903 -- The following is an example of the loop generated for the case of
904 -- a two-dimensional array:
909 -- for L1b in 1 .. 100 loop
913 -- for L3b in 1 .. 100 loop
914 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
915 -- R4b := Tm1X2'succ(R4b);
918 -- R2b := Tm1X1'succ(R2b);
922 -- Here Rev is False, and Tm1Xn are the subscript types for the right
923 -- hand side. The declarations of R2b and R4b are inserted before the
924 -- original assignment statement.
926 function Expand_Assign_Array_Loop
933 Rev
: Boolean) return Node_Id
935 Loc
: constant Source_Ptr
:= Sloc
(N
);
937 Lnn
: array (1 .. Ndim
) of Entity_Id
;
938 Rnn
: array (1 .. Ndim
) of Entity_Id
;
939 -- Entities used as subscripts on left and right sides
941 L_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
942 R_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
943 -- Left and right index types
955 F_Or_L
:= Name_First
;
959 -- Setup index types and subscript entities
966 L_Index
:= First_Index
(L_Type
);
967 R_Index
:= First_Index
(R_Type
);
969 for J
in 1 .. Ndim
loop
971 Make_Defining_Identifier
(Loc
,
972 Chars
=> New_Internal_Name
('L'));
975 Make_Defining_Identifier
(Loc
,
976 Chars
=> New_Internal_Name
('R'));
978 L_Index_Type
(J
) := Etype
(L_Index
);
979 R_Index_Type
(J
) := Etype
(R_Index
);
981 Next_Index
(L_Index
);
982 Next_Index
(R_Index
);
986 -- Now construct the assignment statement
989 ExprL
: constant List_Id
:= New_List
;
990 ExprR
: constant List_Id
:= New_List
;
993 for J
in 1 .. Ndim
loop
994 Append_To
(ExprL
, New_Occurrence_Of
(Lnn
(J
), Loc
));
995 Append_To
(ExprR
, New_Occurrence_Of
(Rnn
(J
), Loc
));
999 Make_Assignment_Statement
(Loc
,
1001 Make_Indexed_Component
(Loc
,
1002 Prefix
=> Duplicate_Subexpr
(Larray
, Name_Req
=> True),
1003 Expressions
=> ExprL
),
1005 Make_Indexed_Component
(Loc
,
1006 Prefix
=> Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
1007 Expressions
=> ExprR
));
1009 -- We set assignment OK, since there are some cases, e.g. in object
1010 -- declarations, where we are actually assigning into a constant.
1011 -- If there really is an illegality, it was caught long before now,
1012 -- and was flagged when the original assignment was analyzed.
1014 Set_Assignment_OK
(Name
(Assign
));
1016 -- Propagate the No_Ctrl_Actions flag to individual assignments
1018 Set_No_Ctrl_Actions
(Assign
, No_Ctrl_Actions
(N
));
1021 -- Now construct the loop from the inside out, with the last subscript
1022 -- varying most rapidly. Note that Assign is first the raw assignment
1023 -- statement, and then subsequently the loop that wraps it up.
1025 for J
in reverse 1 .. Ndim
loop
1027 Make_Block_Statement
(Loc
,
1028 Declarations
=> New_List
(
1029 Make_Object_Declaration
(Loc
,
1030 Defining_Identifier
=> Rnn
(J
),
1031 Object_Definition
=>
1032 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1034 Make_Attribute_Reference
(Loc
,
1035 Prefix
=> New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1036 Attribute_Name
=> F_Or_L
))),
1038 Handled_Statement_Sequence
=>
1039 Make_Handled_Sequence_Of_Statements
(Loc
,
1040 Statements
=> New_List
(
1041 Make_Implicit_Loop_Statement
(N
,
1043 Make_Iteration_Scheme
(Loc
,
1044 Loop_Parameter_Specification
=>
1045 Make_Loop_Parameter_Specification
(Loc
,
1046 Defining_Identifier
=> Lnn
(J
),
1047 Reverse_Present
=> Rev
,
1048 Discrete_Subtype_Definition
=>
1049 New_Reference_To
(L_Index_Type
(J
), Loc
))),
1051 Statements
=> New_List
(
1054 Make_Assignment_Statement
(Loc
,
1055 Name
=> New_Occurrence_Of
(Rnn
(J
), Loc
),
1057 Make_Attribute_Reference
(Loc
,
1059 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1060 Attribute_Name
=> S_Or_P
,
1061 Expressions
=> New_List
(
1062 New_Occurrence_Of
(Rnn
(J
), Loc
)))))))));
1066 end Expand_Assign_Array_Loop
;
1068 --------------------------
1069 -- Expand_Assign_Record --
1070 --------------------------
1072 -- The only processing required is in the change of representation
1073 -- case, where we must expand the assignment to a series of field
1074 -- by field assignments.
1076 procedure Expand_Assign_Record
(N
: Node_Id
) is
1077 Lhs
: constant Node_Id
:= Name
(N
);
1078 Rhs
: Node_Id
:= Expression
(N
);
1081 -- If change of representation, then extract the real right hand
1082 -- side from the type conversion, and proceed with component-wise
1083 -- assignment, since the two types are not the same as far as the
1084 -- back end is concerned.
1086 if Change_Of_Representation
(N
) then
1087 Rhs
:= Expression
(Rhs
);
1089 -- If this may be a case of a large bit aligned component, then
1090 -- proceed with component-wise assignment, to avoid possible
1091 -- clobbering of other components sharing bits in the first or
1092 -- last byte of the component to be assigned.
1094 elsif Possible_Bit_Aligned_Component
(Lhs
)
1096 Possible_Bit_Aligned_Component
(Rhs
)
1100 -- If neither condition met, then nothing special to do, the back end
1101 -- can handle assignment of the entire component as a single entity.
1107 -- At this stage we know that we must do a component wise assignment
1110 Loc
: constant Source_Ptr
:= Sloc
(N
);
1111 R_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Rhs
));
1112 L_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Lhs
));
1113 Decl
: constant Node_Id
:= Declaration_Node
(R_Typ
);
1117 function Find_Component
1119 Comp
: Entity_Id
) return Entity_Id
;
1120 -- Find the component with the given name in the underlying record
1121 -- declaration for Typ. We need to use the actual entity because
1122 -- the type may be private and resolution by identifier alone would
1125 function Make_Component_List_Assign
1127 U_U
: Boolean := False) return List_Id
;
1128 -- Returns a sequence of statements to assign the components that
1129 -- are referenced in the given component list. The flag U_U is
1130 -- used to force the usage of the inferred value of the variant
1131 -- part expression as the switch for the generated case statement.
1133 function Make_Field_Assign
1135 U_U
: Boolean := False) return Node_Id
;
1136 -- Given C, the entity for a discriminant or component, build an
1137 -- assignment for the corresponding field values. The flag U_U
1138 -- signals the presence of an Unchecked_Union and forces the usage
1139 -- of the inferred discriminant value of C as the right hand side
1140 -- of the assignment.
1142 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
;
1143 -- Given CI, a component items list, construct series of statements
1144 -- for fieldwise assignment of the corresponding components.
1146 --------------------
1147 -- Find_Component --
1148 --------------------
1150 function Find_Component
1152 Comp
: Entity_Id
) return Entity_Id
1154 Utyp
: constant Entity_Id
:= Underlying_Type
(Typ
);
1158 C
:= First_Entity
(Utyp
);
1160 while Present
(C
) loop
1161 if Chars
(C
) = Chars
(Comp
) then
1167 raise Program_Error
;
1170 --------------------------------
1171 -- Make_Component_List_Assign --
1172 --------------------------------
1174 function Make_Component_List_Assign
1176 U_U
: Boolean := False) return List_Id
1178 CI
: constant List_Id
:= Component_Items
(CL
);
1179 VP
: constant Node_Id
:= Variant_Part
(CL
);
1189 Result
:= Make_Field_Assigns
(CI
);
1191 if Present
(VP
) then
1193 V
:= First_Non_Pragma
(Variants
(VP
));
1195 while Present
(V
) loop
1198 DC
:= First
(Discrete_Choices
(V
));
1199 while Present
(DC
) loop
1200 Append_To
(DCH
, New_Copy_Tree
(DC
));
1205 Make_Case_Statement_Alternative
(Loc
,
1206 Discrete_Choices
=> DCH
,
1208 Make_Component_List_Assign
(Component_List
(V
))));
1209 Next_Non_Pragma
(V
);
1212 -- If we have an Unchecked_Union, use the value of the inferred
1213 -- discriminant of the variant part expression as the switch
1214 -- for the case statement. The case statement may later be
1219 New_Copy
(Get_Discriminant_Value
(
1222 Discriminant_Constraint
(Etype
(Rhs
))));
1225 Make_Selected_Component
(Loc
,
1226 Prefix
=> Duplicate_Subexpr
(Rhs
),
1228 Make_Identifier
(Loc
, Chars
(Name
(VP
))));
1232 Make_Case_Statement
(Loc
,
1234 Alternatives
=> Alts
));
1238 end Make_Component_List_Assign
;
1240 -----------------------
1241 -- Make_Field_Assign --
1242 -----------------------
1244 function Make_Field_Assign
1246 U_U
: Boolean := False) return Node_Id
1252 -- In the case of an Unchecked_Union, use the discriminant
1253 -- constraint value as on the right hand side of the assignment.
1257 New_Copy
(Get_Discriminant_Value
(C
,
1259 Discriminant_Constraint
(Etype
(Rhs
))));
1262 Make_Selected_Component
(Loc
,
1263 Prefix
=> Duplicate_Subexpr
(Rhs
),
1264 Selector_Name
=> New_Occurrence_Of
(C
, Loc
));
1268 Make_Assignment_Statement
(Loc
,
1270 Make_Selected_Component
(Loc
,
1271 Prefix
=> Duplicate_Subexpr
(Lhs
),
1273 New_Occurrence_Of
(Find_Component
(L_Typ
, C
), Loc
)),
1274 Expression
=> Expr
);
1276 -- Set Assignment_OK, so discriminants can be assigned
1278 Set_Assignment_OK
(Name
(A
), True);
1280 end Make_Field_Assign
;
1282 ------------------------
1283 -- Make_Field_Assigns --
1284 ------------------------
1286 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
is
1293 while Present
(Item
) loop
1294 if Nkind
(Item
) = N_Component_Declaration
then
1296 (Result
, Make_Field_Assign
(Defining_Identifier
(Item
)));
1303 end Make_Field_Assigns
;
1305 -- Start of processing for Expand_Assign_Record
1308 -- Note that we use the base types for this processing. This results
1309 -- in some extra work in the constrained case, but the change of
1310 -- representation case is so unusual that it is not worth the effort.
1312 -- First copy the discriminants. This is done unconditionally. It
1313 -- is required in the unconstrained left side case, and also in the
1314 -- case where this assignment was constructed during the expansion
1315 -- of a type conversion (since initialization of discriminants is
1316 -- suppressed in this case). It is unnecessary but harmless in
1319 if Has_Discriminants
(L_Typ
) then
1320 F
:= First_Discriminant
(R_Typ
);
1321 while Present
(F
) loop
1323 if Is_Unchecked_Union
(Base_Type
(R_Typ
)) then
1324 Insert_Action
(N
, Make_Field_Assign
(F
, True));
1326 Insert_Action
(N
, Make_Field_Assign
(F
));
1329 Next_Discriminant
(F
);
1333 -- We know the underlying type is a record, but its current view
1334 -- may be private. We must retrieve the usable record declaration.
1336 if Nkind
(Decl
) = N_Private_Type_Declaration
1337 and then Present
(Full_View
(R_Typ
))
1339 RDef
:= Type_Definition
(Declaration_Node
(Full_View
(R_Typ
)));
1341 RDef
:= Type_Definition
(Decl
);
1344 if Nkind
(RDef
) = N_Record_Definition
1345 and then Present
(Component_List
(RDef
))
1348 if Is_Unchecked_Union
(R_Typ
) then
1350 Make_Component_List_Assign
(Component_List
(RDef
), True));
1353 (N
, Make_Component_List_Assign
(Component_List
(RDef
)));
1356 Rewrite
(N
, Make_Null_Statement
(Loc
));
1360 end Expand_Assign_Record
;
1362 -----------------------------------
1363 -- Expand_N_Assignment_Statement --
1364 -----------------------------------
1366 -- This procedure implements various cases where an assignment statement
1367 -- cannot just be passed on to the back end in untransformed state.
1369 procedure Expand_N_Assignment_Statement
(N
: Node_Id
) is
1370 Loc
: constant Source_Ptr
:= Sloc
(N
);
1371 Lhs
: constant Node_Id
:= Name
(N
);
1372 Rhs
: constant Node_Id
:= Expression
(N
);
1373 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Lhs
));
1377 -- First deal with generation of range check if required. For now
1378 -- we do this only for discrete types.
1380 if Do_Range_Check
(Rhs
)
1381 and then Is_Discrete_Type
(Typ
)
1383 Set_Do_Range_Check
(Rhs
, False);
1384 Generate_Range_Check
(Rhs
, Typ
, CE_Range_Check_Failed
);
1387 -- Check for a special case where a high level transformation is
1388 -- required. If we have either of:
1393 -- where P is a reference to a bit packed array, then we have to unwind
1394 -- the assignment. The exact meaning of being a reference to a bit
1395 -- packed array is as follows:
1397 -- An indexed component whose prefix is a bit packed array is a
1398 -- reference to a bit packed array.
1400 -- An indexed component or selected component whose prefix is a
1401 -- reference to a bit packed array is itself a reference ot a
1402 -- bit packed array.
1404 -- The required transformation is
1406 -- Tnn : prefix_type := P;
1407 -- Tnn.field := rhs;
1412 -- Tnn : prefix_type := P;
1413 -- Tnn (subscr) := rhs;
1416 -- Since P is going to be evaluated more than once, any subscripts
1417 -- in P must have their evaluation forced.
1419 if (Nkind
(Lhs
) = N_Indexed_Component
1421 Nkind
(Lhs
) = N_Selected_Component
)
1422 and then Is_Ref_To_Bit_Packed_Array
(Prefix
(Lhs
))
1425 BPAR_Expr
: constant Node_Id
:= Relocate_Node
(Prefix
(Lhs
));
1426 BPAR_Typ
: constant Entity_Id
:= Etype
(BPAR_Expr
);
1427 Tnn
: constant Entity_Id
:=
1428 Make_Defining_Identifier
(Loc
,
1429 Chars
=> New_Internal_Name
('T'));
1432 -- Insert the post assignment first, because we want to copy
1433 -- the BPAR_Expr tree before it gets analyzed in the context
1434 -- of the pre assignment. Note that we do not analyze the
1435 -- post assignment yet (we cannot till we have completed the
1436 -- analysis of the pre assignment). As usual, the analysis
1437 -- of this post assignment will happen on its own when we
1438 -- "run into" it after finishing the current assignment.
1441 Make_Assignment_Statement
(Loc
,
1442 Name
=> New_Copy_Tree
(BPAR_Expr
),
1443 Expression
=> New_Occurrence_Of
(Tnn
, Loc
)));
1445 -- At this stage BPAR_Expr is a reference to a bit packed
1446 -- array where the reference was not expanded in the original
1447 -- tree, since it was on the left side of an assignment. But
1448 -- in the pre-assignment statement (the object definition),
1449 -- BPAR_Expr will end up on the right hand side, and must be
1450 -- reexpanded. To achieve this, we reset the analyzed flag
1451 -- of all selected and indexed components down to the actual
1452 -- indexed component for the packed array.
1456 Set_Analyzed
(Exp
, False);
1458 if Nkind
(Exp
) = N_Selected_Component
1460 Nkind
(Exp
) = N_Indexed_Component
1462 Exp
:= Prefix
(Exp
);
1468 -- Now we can insert and analyze the pre-assignment
1470 -- If the right-hand side requires a transient scope, it has
1471 -- already been placed on the stack. However, the declaration is
1472 -- inserted in the tree outside of this scope, and must reflect
1473 -- the proper scope for its variable. This awkward bit is forced
1474 -- by the stricter scope discipline imposed by GCC 2.97.
1477 Uses_Transient_Scope
: constant Boolean :=
1479 and then N
= Node_To_Be_Wrapped
;
1482 if Uses_Transient_Scope
then
1483 New_Scope
(Scope
(Current_Scope
));
1486 Insert_Before_And_Analyze
(N
,
1487 Make_Object_Declaration
(Loc
,
1488 Defining_Identifier
=> Tnn
,
1489 Object_Definition
=> New_Occurrence_Of
(BPAR_Typ
, Loc
),
1490 Expression
=> BPAR_Expr
));
1492 if Uses_Transient_Scope
then
1497 -- Now fix up the original assignment and continue processing
1499 Rewrite
(Prefix
(Lhs
),
1500 New_Occurrence_Of
(Tnn
, Loc
));
1502 -- We do not need to reanalyze that assignment, and we do not need
1503 -- to worry about references to the temporary, but we do need to
1504 -- make sure that the temporary is not marked as a true constant
1505 -- since we now have a generate assignment to it!
1507 Set_Is_True_Constant
(Tnn
, False);
1511 -- When we have the appropriate type of aggregate in the
1512 -- expression (it has been determined during analysis of the
1513 -- aggregate by setting the delay flag), let's perform in place
1514 -- assignment and thus avoid creating a temporay.
1516 if Is_Delayed_Aggregate
(Rhs
) then
1517 Convert_Aggr_In_Assignment
(N
);
1518 Rewrite
(N
, Make_Null_Statement
(Loc
));
1523 -- Apply discriminant check if required. If Lhs is an access type
1524 -- to a designated type with discriminants, we must always check.
1526 if Has_Discriminants
(Etype
(Lhs
)) then
1528 -- Skip discriminant check if change of representation. Will be
1529 -- done when the change of representation is expanded out.
1531 if not Change_Of_Representation
(N
) then
1532 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
), Lhs
);
1535 -- If the type is private without discriminants, and the full type
1536 -- has discriminants (necessarily with defaults) a check may still be
1537 -- necessary if the Lhs is aliased. The private determinants must be
1538 -- visible to build the discriminant constraints.
1540 -- Only an explicit dereference that comes from source indicates
1541 -- aliasing. Access to formals of protected operations and entries
1542 -- create dereferences but are not semantic aliasings.
1544 elsif Is_Private_Type
(Etype
(Lhs
))
1545 and then Has_Discriminants
(Typ
)
1546 and then Nkind
(Lhs
) = N_Explicit_Dereference
1547 and then Comes_From_Source
(Lhs
)
1550 Lt
: constant Entity_Id
:= Etype
(Lhs
);
1552 Set_Etype
(Lhs
, Typ
);
1553 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
1554 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
1555 Set_Etype
(Lhs
, Lt
);
1558 -- If the Lhs has a private type with unknown discriminants, it
1559 -- may have a full view with discriminants, but those are nameable
1560 -- only in the underlying type, so convert the Rhs to it before
1561 -- potential checking.
1563 elsif Has_Unknown_Discriminants
(Base_Type
(Etype
(Lhs
)))
1564 and then Has_Discriminants
(Typ
)
1566 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
1567 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
1569 -- In the access type case, we need the same discriminant check,
1570 -- and also range checks if we have an access to constrained array.
1572 elsif Is_Access_Type
(Etype
(Lhs
))
1573 and then Is_Constrained
(Designated_Type
(Etype
(Lhs
)))
1575 if Has_Discriminants
(Designated_Type
(Etype
(Lhs
))) then
1577 -- Skip discriminant check if change of representation. Will be
1578 -- done when the change of representation is expanded out.
1580 if not Change_Of_Representation
(N
) then
1581 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
));
1584 elsif Is_Array_Type
(Designated_Type
(Etype
(Lhs
))) then
1585 Apply_Range_Check
(Rhs
, Etype
(Lhs
));
1587 if Is_Constrained
(Etype
(Lhs
)) then
1588 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
1591 if Nkind
(Rhs
) = N_Allocator
then
1593 Target_Typ
: constant Entity_Id
:= Etype
(Expression
(Rhs
));
1594 C_Es
: Check_Result
;
1601 Etype
(Designated_Type
(Etype
(Lhs
))));
1613 -- Apply range check for access type case
1615 elsif Is_Access_Type
(Etype
(Lhs
))
1616 and then Nkind
(Rhs
) = N_Allocator
1617 and then Nkind
(Expression
(Rhs
)) = N_Qualified_Expression
1619 Analyze_And_Resolve
(Expression
(Rhs
));
1621 (Expression
(Rhs
), Designated_Type
(Etype
(Lhs
)));
1624 -- Ada 2005 (AI-231): Generate the run-time check
1626 if Is_Access_Type
(Typ
)
1627 and then Can_Never_Be_Null
(Etype
(Lhs
))
1628 and then not Can_Never_Be_Null
(Etype
(Rhs
))
1630 Apply_Constraint_Check
(Rhs
, Etype
(Lhs
));
1633 -- If we are assigning an access type and the left side is an
1634 -- entity, then make sure that Is_Known_Non_Null properly
1635 -- reflects the state of the entity after the assignment
1637 if Is_Access_Type
(Typ
)
1638 and then Is_Entity_Name
(Lhs
)
1639 and then Known_Non_Null
(Rhs
)
1640 and then Safe_To_Capture_Value
(N
, Entity
(Lhs
))
1642 Set_Is_Known_Non_Null
(Entity
(Lhs
), Known_Non_Null
(Rhs
));
1645 -- Case of assignment to a bit packed array element
1647 if Nkind
(Lhs
) = N_Indexed_Component
1648 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Lhs
)))
1650 Expand_Bit_Packed_Element_Set
(N
);
1653 elsif Is_Tagged_Type
(Typ
)
1654 or else (Controlled_Type
(Typ
) and then not Is_Array_Type
(Typ
))
1656 Tagged_Case
: declare
1657 L
: List_Id
:= No_List
;
1658 Expand_Ctrl_Actions
: constant Boolean := not No_Ctrl_Actions
(N
);
1661 -- In the controlled case, we need to make sure that function
1662 -- calls are evaluated before finalizing the target. In all
1663 -- cases, it makes the expansion easier if the side-effects
1664 -- are removed first.
1666 Remove_Side_Effects
(Lhs
);
1667 Remove_Side_Effects
(Rhs
);
1669 -- Avoid recursion in the mechanism
1673 -- If dispatching assignment, we need to dispatch to _assign
1675 if Is_Class_Wide_Type
(Typ
)
1677 -- If the type is tagged, we may as well use the predefined
1678 -- primitive assignment. This avoids inlining a lot of code
1679 -- and in the class-wide case, the assignment is replaced by
1680 -- dispatch call to _assign. Note that this cannot be done
1681 -- when discriminant checks are locally suppressed (as in
1682 -- extension aggregate expansions) because otherwise the
1683 -- discriminant check will be performed within the _assign
1684 -- call. It is also suppressed for assignmments created by the
1685 -- expander that correspond to initializations, where we do
1686 -- want to copy the tag (No_Ctrl_Actions flag set True).
1687 -- by the expander and we do not need to mess with tags ever
1688 -- (Expand_Ctrl_Actions flag is set True in this case).
1690 or else (Is_Tagged_Type
(Typ
)
1691 and then Chars
(Current_Scope
) /= Name_uAssign
1692 and then Expand_Ctrl_Actions
1693 and then not Discriminant_Checks_Suppressed
(Empty
))
1695 -- Fetch the primitive op _assign and proper type to call
1696 -- it. Because of possible conflits between private and
1697 -- full view the proper type is fetched directly from the
1698 -- operation profile.
1701 Op
: constant Entity_Id
:=
1702 Find_Prim_Op
(Typ
, Name_uAssign
);
1703 F_Typ
: Entity_Id
:= Etype
(First_Formal
(Op
));
1706 -- If the assignment is dispatching, make sure to use the
1707 -- ??? where is rest of this comment ???
1709 if Is_Class_Wide_Type
(Typ
) then
1710 F_Typ
:= Class_Wide_Type
(F_Typ
);
1714 Make_Procedure_Call_Statement
(Loc
,
1715 Name
=> New_Reference_To
(Op
, Loc
),
1716 Parameter_Associations
=> New_List
(
1717 Unchecked_Convert_To
(F_Typ
, Duplicate_Subexpr
(Lhs
)),
1718 Unchecked_Convert_To
(F_Typ
,
1719 Duplicate_Subexpr
(Rhs
)))));
1723 L
:= Make_Tag_Ctrl_Assignment
(N
);
1725 -- We can't afford to have destructive Finalization Actions
1726 -- in the Self assignment case, so if the target and the
1727 -- source are not obviously different, code is generated to
1728 -- avoid the self assignment case
1730 -- if lhs'address /= rhs'address then
1731 -- <code for controlled and/or tagged assignment>
1734 if not Statically_Different
(Lhs
, Rhs
)
1735 and then Expand_Ctrl_Actions
1738 Make_Implicit_If_Statement
(N
,
1742 Make_Attribute_Reference
(Loc
,
1743 Prefix
=> Duplicate_Subexpr
(Lhs
),
1744 Attribute_Name
=> Name_Address
),
1747 Make_Attribute_Reference
(Loc
,
1748 Prefix
=> Duplicate_Subexpr
(Rhs
),
1749 Attribute_Name
=> Name_Address
)),
1751 Then_Statements
=> L
));
1754 -- We need to set up an exception handler for implementing
1755 -- 7.6.1 (18). The remaining adjustments are tackled by the
1756 -- implementation of adjust for record_controllers (see
1759 -- This is skipped if we have no finalization
1761 if Expand_Ctrl_Actions
1762 and then not Restriction_Active
(No_Finalization
)
1765 Make_Block_Statement
(Loc
,
1766 Handled_Statement_Sequence
=>
1767 Make_Handled_Sequence_Of_Statements
(Loc
,
1769 Exception_Handlers
=> New_List
(
1770 Make_Exception_Handler
(Loc
,
1771 Exception_Choices
=>
1772 New_List
(Make_Others_Choice
(Loc
)),
1773 Statements
=> New_List
(
1774 Make_Raise_Program_Error
(Loc
,
1776 PE_Finalize_Raised_Exception
)
1782 Make_Block_Statement
(Loc
,
1783 Handled_Statement_Sequence
=>
1784 Make_Handled_Sequence_Of_Statements
(Loc
, Statements
=> L
)));
1786 -- If no restrictions on aborts, protect the whole assignement
1787 -- for controlled objects as per 9.8(11)
1789 if Controlled_Type
(Typ
)
1790 and then Expand_Ctrl_Actions
1791 and then Abort_Allowed
1794 Blk
: constant Entity_Id
:=
1796 (E_Block
, Current_Scope
, Sloc
(N
), 'B');
1799 Set_Scope
(Blk
, Current_Scope
);
1800 Set_Etype
(Blk
, Standard_Void_Type
);
1801 Set_Identifier
(N
, New_Occurrence_Of
(Blk
, Sloc
(N
)));
1803 Prepend_To
(L
, Build_Runtime_Call
(Loc
, RE_Abort_Defer
));
1804 Set_At_End_Proc
(Handled_Statement_Sequence
(N
),
1805 New_Occurrence_Of
(RTE
(RE_Abort_Undefer_Direct
), Loc
));
1806 Expand_At_End_Handler
1807 (Handled_Statement_Sequence
(N
), Blk
);
1817 elsif Is_Array_Type
(Typ
) then
1819 Actual_Rhs
: Node_Id
:= Rhs
;
1822 while Nkind
(Actual_Rhs
) = N_Type_Conversion
1824 Nkind
(Actual_Rhs
) = N_Qualified_Expression
1826 Actual_Rhs
:= Expression
(Actual_Rhs
);
1829 Expand_Assign_Array
(N
, Actual_Rhs
);
1835 elsif Is_Record_Type
(Typ
) then
1836 Expand_Assign_Record
(N
);
1839 -- Scalar types. This is where we perform the processing related
1840 -- to the requirements of (RM 13.9.1(9-11)) concerning the handling
1841 -- of invalid scalar values.
1843 elsif Is_Scalar_Type
(Typ
) then
1845 -- Case where right side is known valid
1847 if Expr_Known_Valid
(Rhs
) then
1849 -- Here the right side is valid, so it is fine. The case to
1850 -- deal with is when the left side is a local variable reference
1851 -- whose value is not currently known to be valid. If this is
1852 -- the case, and the assignment appears in an unconditional
1853 -- context, then we can mark the left side as now being valid.
1855 if Is_Local_Variable_Reference
(Lhs
)
1856 and then not Is_Known_Valid
(Entity
(Lhs
))
1857 and then In_Unconditional_Context
(N
)
1859 Set_Is_Known_Valid
(Entity
(Lhs
), True);
1862 -- Case where right side may be invalid in the sense of the RM
1863 -- reference above. The RM does not require that we check for
1864 -- the validity on an assignment, but it does require that the
1865 -- assignment of an invalid value not cause erroneous behavior.
1867 -- The general approach in GNAT is to use the Is_Known_Valid flag
1868 -- to avoid the need for validity checking on assignments. However
1869 -- in some cases, we have to do validity checking in order to make
1870 -- sure that the setting of this flag is correct.
1873 -- Validate right side if we are validating copies
1875 if Validity_Checks_On
1876 and then Validity_Check_Copies
1880 -- We can propagate this to the left side where appropriate
1882 if Is_Local_Variable_Reference
(Lhs
)
1883 and then not Is_Known_Valid
(Entity
(Lhs
))
1884 and then In_Unconditional_Context
(N
)
1886 Set_Is_Known_Valid
(Entity
(Lhs
), True);
1889 -- Otherwise check to see what should be done
1891 -- If left side is a local variable, then we just set its
1892 -- flag to indicate that its value may no longer be valid,
1893 -- since we are copying a potentially invalid value.
1895 elsif Is_Local_Variable_Reference
(Lhs
) then
1896 Set_Is_Known_Valid
(Entity
(Lhs
), False);
1898 -- Check for case of a nonlocal variable on the left side
1899 -- which is currently known to be valid. In this case, we
1900 -- simply ensure that the right side is valid. We only play
1901 -- the game of copying validity status for local variables,
1902 -- since we are doing this statically, not by tracing the
1905 elsif Is_Entity_Name
(Lhs
)
1906 and then Is_Known_Valid
(Entity
(Lhs
))
1908 -- Note that the Ensure_Valid call is ignored if the
1909 -- Validity_Checking mode is set to none so we do not
1910 -- need to worry about that case here.
1914 -- In all other cases, we can safely copy an invalid value
1915 -- without worrying about the status of the left side. Since
1916 -- it is not a variable reference it will not be considered
1917 -- as being known to be valid in any case.
1925 -- Defend against invalid subscripts on left side if we are in
1926 -- standard validity checking mode. No need to do this if we
1927 -- are checking all subscripts.
1929 if Validity_Checks_On
1930 and then Validity_Check_Default
1931 and then not Validity_Check_Subscripts
1933 Check_Valid_Lvalue_Subscripts
(Lhs
);
1937 when RE_Not_Available
=>
1939 end Expand_N_Assignment_Statement
;
1941 ------------------------------
1942 -- Expand_N_Block_Statement --
1943 ------------------------------
1945 -- Encode entity names defined in block statement
1947 procedure Expand_N_Block_Statement
(N
: Node_Id
) is
1949 Qualify_Entity_Names
(N
);
1950 end Expand_N_Block_Statement
;
1952 -----------------------------
1953 -- Expand_N_Case_Statement --
1954 -----------------------------
1956 procedure Expand_N_Case_Statement
(N
: Node_Id
) is
1957 Loc
: constant Source_Ptr
:= Sloc
(N
);
1958 Expr
: constant Node_Id
:= Expression
(N
);
1966 -- Check for the situation where we know at compile time which
1967 -- branch will be taken
1969 if Compile_Time_Known_Value
(Expr
) then
1970 Alt
:= Find_Static_Alternative
(N
);
1972 -- Move the statements from this alternative after the case
1973 -- statement. They are already analyzed, so will be skipped
1976 Insert_List_After
(N
, Statements
(Alt
));
1978 -- That leaves the case statement as a shell. The alternative
1979 -- that will be executed is reset to a null list. So now we can
1980 -- kill the entire case statement.
1982 Kill_Dead_Code
(Expression
(N
));
1983 Kill_Dead_Code
(Alternatives
(N
));
1984 Rewrite
(N
, Make_Null_Statement
(Loc
));
1988 -- Here if the choice is not determined at compile time
1991 Last_Alt
: constant Node_Id
:= Last
(Alternatives
(N
));
1993 Others_Present
: Boolean;
1994 Others_Node
: Node_Id
;
1996 Then_Stms
: List_Id
;
1997 Else_Stms
: List_Id
;
2000 if Nkind
(First
(Discrete_Choices
(Last_Alt
))) = N_Others_Choice
then
2001 Others_Present
:= True;
2002 Others_Node
:= Last_Alt
;
2004 Others_Present
:= False;
2007 -- First step is to worry about possible invalid argument. The RM
2008 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
2009 -- outside the base range), then Constraint_Error must be raised.
2011 -- Case of validity check required (validity checks are on, the
2012 -- expression is not known to be valid, and the case statement
2013 -- comes from source -- no need to validity check internally
2014 -- generated case statements).
2016 if Validity_Check_Default
then
2017 Ensure_Valid
(Expr
);
2020 -- If there is only a single alternative, just replace it with
2021 -- the sequence of statements since obviously that is what is
2022 -- going to be executed in all cases.
2024 Len
:= List_Length
(Alternatives
(N
));
2027 -- We still need to evaluate the expression if it has any
2030 Remove_Side_Effects
(Expression
(N
));
2032 Insert_List_After
(N
, Statements
(First
(Alternatives
(N
))));
2034 -- That leaves the case statement as a shell. The alternative
2035 -- that will be executed is reset to a null list. So now we can
2036 -- kill the entire case statement.
2038 Kill_Dead_Code
(Expression
(N
));
2039 Rewrite
(N
, Make_Null_Statement
(Loc
));
2043 -- An optimization. If there are only two alternatives, and only
2044 -- a single choice, then rewrite the whole case statement as an
2045 -- if statement, since this can result in susbequent optimizations.
2046 -- This helps not only with case statements in the source of a
2047 -- simple form, but also with generated code (discriminant check
2048 -- functions in particular)
2051 Chlist
:= Discrete_Choices
(First
(Alternatives
(N
)));
2053 if List_Length
(Chlist
) = 1 then
2054 Choice
:= First
(Chlist
);
2056 Then_Stms
:= Statements
(First
(Alternatives
(N
)));
2057 Else_Stms
:= Statements
(Last
(Alternatives
(N
)));
2059 -- For TRUE, generate "expression", not expression = true
2061 if Nkind
(Choice
) = N_Identifier
2062 and then Entity
(Choice
) = Standard_True
2064 Cond
:= Expression
(N
);
2066 -- For FALSE, generate "expression" and switch then/else
2068 elsif Nkind
(Choice
) = N_Identifier
2069 and then Entity
(Choice
) = Standard_False
2071 Cond
:= Expression
(N
);
2072 Else_Stms
:= Statements
(First
(Alternatives
(N
)));
2073 Then_Stms
:= Statements
(Last
(Alternatives
(N
)));
2075 -- For a range, generate "expression in range"
2077 elsif Nkind
(Choice
) = N_Range
2078 or else (Nkind
(Choice
) = N_Attribute_Reference
2079 and then Attribute_Name
(Choice
) = Name_Range
)
2080 or else (Is_Entity_Name
(Choice
)
2081 and then Is_Type
(Entity
(Choice
)))
2082 or else Nkind
(Choice
) = N_Subtype_Indication
2086 Left_Opnd
=> Expression
(N
),
2087 Right_Opnd
=> Relocate_Node
(Choice
));
2089 -- For any other subexpression "expression = value"
2094 Left_Opnd
=> Expression
(N
),
2095 Right_Opnd
=> Relocate_Node
(Choice
));
2098 -- Now rewrite the case as an IF
2101 Make_If_Statement
(Loc
,
2103 Then_Statements
=> Then_Stms
,
2104 Else_Statements
=> Else_Stms
));
2110 -- If the last alternative is not an Others choice, replace it
2111 -- with an N_Others_Choice. Note that we do not bother to call
2112 -- Analyze on the modified case statement, since it's only effect
2113 -- would be to compute the contents of the Others_Discrete_Choices
2114 -- which is not needed by the back end anyway.
2116 -- The reason we do this is that the back end always needs some
2117 -- default for a switch, so if we have not supplied one in the
2118 -- processing above for validity checking, then we need to
2121 if not Others_Present
then
2122 Others_Node
:= Make_Others_Choice
(Sloc
(Last_Alt
));
2123 Set_Others_Discrete_Choices
2124 (Others_Node
, Discrete_Choices
(Last_Alt
));
2125 Set_Discrete_Choices
(Last_Alt
, New_List
(Others_Node
));
2128 end Expand_N_Case_Statement
;
2130 -----------------------------
2131 -- Expand_N_Exit_Statement --
2132 -----------------------------
2134 -- The only processing required is to deal with a possible C/Fortran
2135 -- boolean value used as the condition for the exit statement.
2137 procedure Expand_N_Exit_Statement
(N
: Node_Id
) is
2139 Adjust_Condition
(Condition
(N
));
2140 end Expand_N_Exit_Statement
;
2142 -----------------------------
2143 -- Expand_N_Goto_Statement --
2144 -----------------------------
2146 -- Add poll before goto if polling active
2148 procedure Expand_N_Goto_Statement
(N
: Node_Id
) is
2150 Generate_Poll_Call
(N
);
2151 end Expand_N_Goto_Statement
;
2153 ---------------------------
2154 -- Expand_N_If_Statement --
2155 ---------------------------
2157 -- First we deal with the case of C and Fortran convention boolean
2158 -- values, with zero/non-zero semantics.
2160 -- Second, we deal with the obvious rewriting for the cases where the
2161 -- condition of the IF is known at compile time to be True or False.
2163 -- Third, we remove elsif parts which have non-empty Condition_Actions
2164 -- and rewrite as independent if statements. For example:
2175 -- <<condition actions of y>>
2181 -- This rewriting is needed if at least one elsif part has a non-empty
2182 -- Condition_Actions list. We also do the same processing if there is
2183 -- a constant condition in an elsif part (in conjunction with the first
2184 -- processing step mentioned above, for the recursive call made to deal
2185 -- with the created inner if, this deals with properly optimizing the
2186 -- cases of constant elsif conditions).
2188 procedure Expand_N_If_Statement
(N
: Node_Id
) is
2189 Loc
: constant Source_Ptr
:= Sloc
(N
);
2195 Adjust_Condition
(Condition
(N
));
2197 -- The following loop deals with constant conditions for the IF. We
2198 -- need a loop because as we eliminate False conditions, we grab the
2199 -- first elsif condition and use it as the primary condition.
2201 while Compile_Time_Known_Value
(Condition
(N
)) loop
2203 -- If condition is True, we can simply rewrite the if statement
2204 -- now by replacing it by the series of then statements.
2206 if Is_True
(Expr_Value
(Condition
(N
))) then
2208 -- All the else parts can be killed
2210 Kill_Dead_Code
(Elsif_Parts
(N
));
2211 Kill_Dead_Code
(Else_Statements
(N
));
2213 Hed
:= Remove_Head
(Then_Statements
(N
));
2214 Insert_List_After
(N
, Then_Statements
(N
));
2218 -- If condition is False, then we can delete the condition and
2219 -- the Then statements
2222 -- We do not delete the condition if constant condition
2223 -- warnings are enabled, since otherwise we end up deleting
2224 -- the desired warning. Of course the backend will get rid
2225 -- of this True/False test anyway, so nothing is lost here.
2227 if not Constant_Condition_Warnings
then
2228 Kill_Dead_Code
(Condition
(N
));
2231 Kill_Dead_Code
(Then_Statements
(N
));
2233 -- If there are no elsif statements, then we simply replace
2234 -- the entire if statement by the sequence of else statements.
2236 if No
(Elsif_Parts
(N
)) then
2238 if No
(Else_Statements
(N
))
2239 or else Is_Empty_List
(Else_Statements
(N
))
2242 Make_Null_Statement
(Sloc
(N
)));
2245 Hed
:= Remove_Head
(Else_Statements
(N
));
2246 Insert_List_After
(N
, Else_Statements
(N
));
2252 -- If there are elsif statements, the first of them becomes
2253 -- the if/then section of the rebuilt if statement This is
2254 -- the case where we loop to reprocess this copied condition.
2257 Hed
:= Remove_Head
(Elsif_Parts
(N
));
2258 Insert_Actions
(N
, Condition_Actions
(Hed
));
2259 Set_Condition
(N
, Condition
(Hed
));
2260 Set_Then_Statements
(N
, Then_Statements
(Hed
));
2262 if Is_Empty_List
(Elsif_Parts
(N
)) then
2263 Set_Elsif_Parts
(N
, No_List
);
2269 -- Loop through elsif parts, dealing with constant conditions and
2270 -- possible expression actions that are present.
2272 if Present
(Elsif_Parts
(N
)) then
2273 E
:= First
(Elsif_Parts
(N
));
2274 while Present
(E
) loop
2275 Adjust_Condition
(Condition
(E
));
2277 -- If there are condition actions, then we rewrite the if
2278 -- statement as indicated above. We also do the same rewrite
2279 -- if the condition is True or False. The further processing
2280 -- of this constant condition is then done by the recursive
2281 -- call to expand the newly created if statement
2283 if Present
(Condition_Actions
(E
))
2284 or else Compile_Time_Known_Value
(Condition
(E
))
2286 -- Note this is not an implicit if statement, since it is
2287 -- part of an explicit if statement in the source (or of an
2288 -- implicit if statement that has already been tested).
2291 Make_If_Statement
(Sloc
(E
),
2292 Condition
=> Condition
(E
),
2293 Then_Statements
=> Then_Statements
(E
),
2294 Elsif_Parts
=> No_List
,
2295 Else_Statements
=> Else_Statements
(N
));
2297 -- Elsif parts for new if come from remaining elsif's of parent
2299 while Present
(Next
(E
)) loop
2300 if No
(Elsif_Parts
(New_If
)) then
2301 Set_Elsif_Parts
(New_If
, New_List
);
2304 Append
(Remove_Next
(E
), Elsif_Parts
(New_If
));
2307 Set_Else_Statements
(N
, New_List
(New_If
));
2309 if Present
(Condition_Actions
(E
)) then
2310 Insert_List_Before
(New_If
, Condition_Actions
(E
));
2315 if Is_Empty_List
(Elsif_Parts
(N
)) then
2316 Set_Elsif_Parts
(N
, No_List
);
2322 -- No special processing for that elsif part, move to next
2330 -- Some more optimizations applicable if we still have an IF statement
2332 if Nkind
(N
) /= N_If_Statement
then
2336 -- Another optimization, special cases that can be simplified
2338 -- if expression then
2344 -- can be changed to:
2346 -- return expression;
2350 -- if expression then
2356 -- can be changed to:
2358 -- return not (expression);
2360 if Nkind
(N
) = N_If_Statement
2361 and then No
(Elsif_Parts
(N
))
2362 and then Present
(Else_Statements
(N
))
2363 and then List_Length
(Then_Statements
(N
)) = 1
2364 and then List_Length
(Else_Statements
(N
)) = 1
2367 Then_Stm
: constant Node_Id
:= First
(Then_Statements
(N
));
2368 Else_Stm
: constant Node_Id
:= First
(Else_Statements
(N
));
2371 if Nkind
(Then_Stm
) = N_Return_Statement
2373 Nkind
(Else_Stm
) = N_Return_Statement
2376 Then_Expr
: constant Node_Id
:= Expression
(Then_Stm
);
2377 Else_Expr
: constant Node_Id
:= Expression
(Else_Stm
);
2380 if Nkind
(Then_Expr
) = N_Identifier
2382 Nkind
(Else_Expr
) = N_Identifier
2384 if Entity
(Then_Expr
) = Standard_True
2385 and then Entity
(Else_Expr
) = Standard_False
2388 Make_Return_Statement
(Loc
,
2389 Expression
=> Relocate_Node
(Condition
(N
))));
2393 elsif Entity
(Then_Expr
) = Standard_False
2394 and then Entity
(Else_Expr
) = Standard_True
2397 Make_Return_Statement
(Loc
,
2400 Right_Opnd
=> Relocate_Node
(Condition
(N
)))));
2409 end Expand_N_If_Statement
;
2411 -----------------------------
2412 -- Expand_N_Loop_Statement --
2413 -----------------------------
2415 -- 1. Deal with while condition for C/Fortran boolean
2416 -- 2. Deal with loops with a non-standard enumeration type range
2417 -- 3. Deal with while loops where Condition_Actions is set
2418 -- 4. Insert polling call if required
2420 procedure Expand_N_Loop_Statement
(N
: Node_Id
) is
2421 Loc
: constant Source_Ptr
:= Sloc
(N
);
2422 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
2425 if Present
(Isc
) then
2426 Adjust_Condition
(Condition
(Isc
));
2429 if Is_Non_Empty_List
(Statements
(N
)) then
2430 Generate_Poll_Call
(First
(Statements
(N
)));
2437 -- Handle the case where we have a for loop with the range type being
2438 -- an enumeration type with non-standard representation. In this case
2441 -- for x in [reverse] a .. b loop
2447 -- for xP in [reverse] integer
2448 -- range etype'Pos (a) .. etype'Pos (b) loop
2450 -- x : constant etype := Pos_To_Rep (xP);
2456 if Present
(Loop_Parameter_Specification
(Isc
)) then
2458 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Isc
);
2459 Loop_Id
: constant Entity_Id
:= Defining_Identifier
(LPS
);
2460 Ltype
: constant Entity_Id
:= Etype
(Loop_Id
);
2461 Btype
: constant Entity_Id
:= Base_Type
(Ltype
);
2466 if not Is_Enumeration_Type
(Btype
)
2467 or else No
(Enum_Pos_To_Rep
(Btype
))
2473 Make_Defining_Identifier
(Loc
,
2474 Chars
=> New_External_Name
(Chars
(Loop_Id
), 'P'));
2476 -- If the type has a contiguous representation, successive
2477 -- values can be generated as offsets from the first literal.
2479 if Has_Contiguous_Rep
(Btype
) then
2481 Unchecked_Convert_To
(Btype
,
2484 Make_Integer_Literal
(Loc
,
2485 Enumeration_Rep
(First_Literal
(Btype
))),
2486 Right_Opnd
=> New_Reference_To
(New_Id
, Loc
)));
2488 -- Use the constructed array Enum_Pos_To_Rep
2491 Make_Indexed_Component
(Loc
,
2492 Prefix
=> New_Reference_To
(Enum_Pos_To_Rep
(Btype
), Loc
),
2493 Expressions
=> New_List
(New_Reference_To
(New_Id
, Loc
)));
2497 Make_Loop_Statement
(Loc
,
2498 Identifier
=> Identifier
(N
),
2501 Make_Iteration_Scheme
(Loc
,
2502 Loop_Parameter_Specification
=>
2503 Make_Loop_Parameter_Specification
(Loc
,
2504 Defining_Identifier
=> New_Id
,
2505 Reverse_Present
=> Reverse_Present
(LPS
),
2507 Discrete_Subtype_Definition
=>
2508 Make_Subtype_Indication
(Loc
,
2511 New_Reference_To
(Standard_Natural
, Loc
),
2514 Make_Range_Constraint
(Loc
,
2519 Make_Attribute_Reference
(Loc
,
2521 New_Reference_To
(Btype
, Loc
),
2523 Attribute_Name
=> Name_Pos
,
2525 Expressions
=> New_List
(
2527 (Type_Low_Bound
(Ltype
)))),
2530 Make_Attribute_Reference
(Loc
,
2532 New_Reference_To
(Btype
, Loc
),
2534 Attribute_Name
=> Name_Pos
,
2536 Expressions
=> New_List
(
2538 (Type_High_Bound
(Ltype
))))))))),
2540 Statements
=> New_List
(
2541 Make_Block_Statement
(Loc
,
2542 Declarations
=> New_List
(
2543 Make_Object_Declaration
(Loc
,
2544 Defining_Identifier
=> Loop_Id
,
2545 Constant_Present
=> True,
2546 Object_Definition
=> New_Reference_To
(Ltype
, Loc
),
2547 Expression
=> Expr
)),
2549 Handled_Statement_Sequence
=>
2550 Make_Handled_Sequence_Of_Statements
(Loc
,
2551 Statements
=> Statements
(N
)))),
2553 End_Label
=> End_Label
(N
)));
2557 -- Second case, if we have a while loop with Condition_Actions set,
2558 -- then we change it into a plain loop:
2567 -- <<condition actions>>
2573 and then Present
(Condition_Actions
(Isc
))
2580 Make_Exit_Statement
(Sloc
(Condition
(Isc
)),
2582 Make_Op_Not
(Sloc
(Condition
(Isc
)),
2583 Right_Opnd
=> Condition
(Isc
)));
2585 Prepend
(ES
, Statements
(N
));
2586 Insert_List_Before
(ES
, Condition_Actions
(Isc
));
2588 -- This is not an implicit loop, since it is generated in
2589 -- response to the loop statement being processed. If this
2590 -- is itself implicit, the restriction has already been
2591 -- checked. If not, it is an explicit loop.
2594 Make_Loop_Statement
(Sloc
(N
),
2595 Identifier
=> Identifier
(N
),
2596 Statements
=> Statements
(N
),
2597 End_Label
=> End_Label
(N
)));
2602 end Expand_N_Loop_Statement
;
2604 -------------------------------
2605 -- Expand_N_Return_Statement --
2606 -------------------------------
2608 procedure Expand_N_Return_Statement
(N
: Node_Id
) is
2609 Loc
: constant Source_Ptr
:= Sloc
(N
);
2610 Exp
: constant Node_Id
:= Expression
(N
);
2614 Scope_Id
: Entity_Id
;
2618 Goto_Stat
: Node_Id
;
2621 Return_Type
: Entity_Id
;
2622 Result_Exp
: Node_Id
;
2623 Result_Id
: Entity_Id
;
2624 Result_Obj
: Node_Id
;
2627 -- Case where returned expression is present
2629 if Present
(Exp
) then
2631 -- Always normalize C/Fortran boolean result. This is not always
2632 -- necessary, but it seems a good idea to minimize the passing
2633 -- around of non-normalized values, and in any case this handles
2634 -- the processing of barrier functions for protected types, which
2635 -- turn the condition into a return statement.
2637 Exptyp
:= Etype
(Exp
);
2639 if Is_Boolean_Type
(Exptyp
)
2640 and then Nonzero_Is_True
(Exptyp
)
2642 Adjust_Condition
(Exp
);
2643 Adjust_Result_Type
(Exp
, Exptyp
);
2646 -- Do validity check if enabled for returns
2648 if Validity_Checks_On
2649 and then Validity_Check_Returns
2655 -- Find relevant enclosing scope from which return is returning
2657 Cur_Idx
:= Scope_Stack
.Last
;
2659 Scope_Id
:= Scope_Stack
.Table
(Cur_Idx
).Entity
;
2661 if Ekind
(Scope_Id
) /= E_Block
2662 and then Ekind
(Scope_Id
) /= E_Loop
2667 Cur_Idx
:= Cur_Idx
- 1;
2668 pragma Assert
(Cur_Idx
>= 0);
2673 Kind
:= Ekind
(Scope_Id
);
2675 -- If it is a return from procedures do no extra steps
2677 if Kind
= E_Procedure
or else Kind
= E_Generic_Procedure
then
2681 pragma Assert
(Is_Entry
(Scope_Id
));
2683 -- Look at the enclosing block to see whether the return is from
2684 -- an accept statement or an entry body.
2686 for J
in reverse 0 .. Cur_Idx
loop
2687 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
2688 exit when Is_Concurrent_Type
(Scope_Id
);
2691 -- If it is a return from accept statement it should be expanded
2692 -- as a call to RTS Complete_Rendezvous and a goto to the end of
2695 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
2696 -- Expand_N_Accept_Alternative in exp_ch9.adb)
2698 if Is_Task_Type
(Scope_Id
) then
2700 Call
:= (Make_Procedure_Call_Statement
(Loc
,
2701 Name
=> New_Reference_To
2702 (RTE
(RE_Complete_Rendezvous
), Loc
)));
2703 Insert_Before
(N
, Call
);
2704 -- why not insert actions here???
2707 Acc_Stat
:= Parent
(N
);
2708 while Nkind
(Acc_Stat
) /= N_Accept_Statement
loop
2709 Acc_Stat
:= Parent
(Acc_Stat
);
2712 Lab_Node
:= Last
(Statements
2713 (Handled_Statement_Sequence
(Acc_Stat
)));
2715 Goto_Stat
:= Make_Goto_Statement
(Loc
,
2716 Name
=> New_Occurrence_Of
2717 (Entity
(Identifier
(Lab_Node
)), Loc
));
2719 Set_Analyzed
(Goto_Stat
);
2721 Rewrite
(N
, Goto_Stat
);
2724 -- If it is a return from an entry body, put a Complete_Entry_Body
2725 -- call in front of the return.
2727 elsif Is_Protected_Type
(Scope_Id
) then
2730 Make_Procedure_Call_Statement
(Loc
,
2731 Name
=> New_Reference_To
2732 (RTE
(RE_Complete_Entry_Body
), Loc
),
2733 Parameter_Associations
=> New_List
2734 (Make_Attribute_Reference
(Loc
,
2738 (Corresponding_Body
(Parent
(Scope_Id
))),
2740 Attribute_Name
=> Name_Unchecked_Access
)));
2742 Insert_Before
(N
, Call
);
2751 Return_Type
:= Etype
(Scope_Id
);
2752 Utyp
:= Underlying_Type
(Return_Type
);
2754 -- Check the result expression of a scalar function against
2755 -- the subtype of the function by inserting a conversion.
2756 -- This conversion must eventually be performed for other
2757 -- classes of types, but for now it's only done for scalars.
2760 if Is_Scalar_Type
(T
) then
2761 Rewrite
(Exp
, Convert_To
(Return_Type
, Exp
));
2765 -- Implement the rules of 6.5(8-10), which require a tag check in
2766 -- the case of a limited tagged return type, and tag reassignment
2767 -- for nonlimited tagged results. These actions are needed when
2768 -- the return type is a specific tagged type and the result
2769 -- expression is a conversion or a formal parameter, because in
2770 -- that case the tag of the expression might differ from the tag
2771 -- of the specific result type.
2773 if Is_Tagged_Type
(Utyp
)
2774 and then not Is_Class_Wide_Type
(Utyp
)
2775 and then (Nkind
(Exp
) = N_Type_Conversion
2776 or else Nkind
(Exp
) = N_Unchecked_Type_Conversion
2777 or else (Is_Entity_Name
(Exp
)
2778 and then Ekind
(Entity
(Exp
)) in Formal_Kind
))
2780 -- When the return type is limited, perform a check that the
2781 -- tag of the result is the same as the tag of the return type.
2783 if Is_Limited_Type
(Return_Type
) then
2785 Make_Raise_Constraint_Error
(Loc
,
2789 Make_Selected_Component
(Loc
,
2790 Prefix
=> Duplicate_Subexpr
(Exp
),
2792 New_Reference_To
(First_Tag_Component
(Utyp
), Loc
)),
2794 Unchecked_Convert_To
(RTE
(RE_Tag
),
2797 (Access_Disp_Table
(Base_Type
(Utyp
)))),
2799 Reason
=> CE_Tag_Check_Failed
));
2801 -- If the result type is a specific nonlimited tagged type,
2802 -- then we have to ensure that the tag of the result is that
2803 -- of the result type. This is handled by making a copy of the
2804 -- expression in the case where it might have a different tag,
2805 -- namely when the expression is a conversion or a formal
2806 -- parameter. We create a new object of the result type and
2807 -- initialize it from the expression, which will implicitly
2808 -- force the tag to be set appropriately.
2812 Make_Defining_Identifier
(Loc
, New_Internal_Name
('R'));
2813 Result_Exp
:= New_Reference_To
(Result_Id
, Loc
);
2816 Make_Object_Declaration
(Loc
,
2817 Defining_Identifier
=> Result_Id
,
2818 Object_Definition
=> New_Reference_To
(Return_Type
, Loc
),
2819 Constant_Present
=> True,
2820 Expression
=> Relocate_Node
(Exp
));
2822 Set_Assignment_OK
(Result_Obj
);
2823 Insert_Action
(Exp
, Result_Obj
);
2825 Rewrite
(Exp
, Result_Exp
);
2826 Analyze_And_Resolve
(Exp
, Return_Type
);
2829 -- Ada 2005 (AI-344): If the result type is class-wide, then insert
2830 -- a check that the level of the return expression's underlying type
2831 -- is not deeper than the level of the master enclosing the function.
2832 -- Always generate the check when the type of the return expression
2833 -- is class-wide, when it's a type conversion, or when it's a formal
2834 -- parameter. Otherwise, suppress the check in the case where the
2835 -- return expression has a specific type whose level is known not to
2836 -- be statically deeper than the function's result type.
2838 elsif Ada_Version
>= Ada_05
2839 and then Is_Class_Wide_Type
(Return_Type
)
2840 and then not Scope_Suppress
(Accessibility_Check
)
2842 (Is_Class_Wide_Type
(Etype
(Exp
))
2843 or else Nkind
(Exp
) = N_Type_Conversion
2844 or else Nkind
(Exp
) = N_Unchecked_Type_Conversion
2845 or else (Is_Entity_Name
(Exp
)
2846 and then Ekind
(Entity
(Exp
)) in Formal_Kind
)
2847 or else Scope_Depth
(Enclosing_Dynamic_Scope
(Etype
(Exp
))) >
2848 Scope_Depth
(Enclosing_Dynamic_Scope
(Scope_Id
)))
2851 Make_Raise_Program_Error
(Loc
,
2855 Make_Function_Call
(Loc
,
2858 (RTE
(RE_Get_Access_Level
), Loc
),
2859 Parameter_Associations
=>
2860 New_List
(Make_Attribute_Reference
(Loc
,
2862 Duplicate_Subexpr
(Exp
),
2866 Make_Integer_Literal
(Loc
,
2867 Scope_Depth
(Enclosing_Dynamic_Scope
(Scope_Id
)))),
2868 Reason
=> PE_Accessibility_Check_Failed
));
2871 -- Deal with returning variable length objects and controlled types
2873 -- Nothing to do if we are returning by reference, or this is not
2874 -- a type that requires special processing (indicated by the fact
2875 -- that it requires a cleanup scope for the secondary stack case)
2877 if Is_Return_By_Reference_Type
(T
)
2878 or else not Requires_Transient_Scope
(Return_Type
)
2882 -- Case of secondary stack not used
2884 elsif Function_Returns_With_DSP
(Scope_Id
) then
2886 -- Here what we need to do is to always return by reference, since
2887 -- we will return with the stack pointer depressed. We may need to
2888 -- do a copy to a local temporary before doing this return.
2890 No_Secondary_Stack_Case
: declare
2891 Local_Copy_Required
: Boolean := False;
2892 -- Set to True if a local copy is required
2894 Copy_Ent
: Entity_Id
;
2895 -- Used for the target entity if a copy is required
2898 -- Declaration used to create copy if needed
2900 procedure Test_Copy_Required
(Expr
: Node_Id
);
2901 -- Determines if Expr represents a return value for which a
2902 -- copy is required. More specifically, a copy is not required
2903 -- if Expr represents an object or component of an object that
2904 -- is either in the local subprogram frame, or is constant.
2905 -- If a copy is required, then Local_Copy_Required is set True.
2907 ------------------------
2908 -- Test_Copy_Required --
2909 ------------------------
2911 procedure Test_Copy_Required
(Expr
: Node_Id
) is
2915 -- If component, test prefix (object containing component)
2917 if Nkind
(Expr
) = N_Indexed_Component
2919 Nkind
(Expr
) = N_Selected_Component
2921 Test_Copy_Required
(Prefix
(Expr
));
2924 -- See if we have an entity name
2926 elsif Is_Entity_Name
(Expr
) then
2927 Ent
:= Entity
(Expr
);
2929 -- Constant entity is always OK, no copy required
2931 if Ekind
(Ent
) = E_Constant
then
2934 -- No copy required for local variable
2936 elsif Ekind
(Ent
) = E_Variable
2937 and then Scope
(Ent
) = Current_Subprogram
2943 -- All other cases require a copy
2945 Local_Copy_Required
:= True;
2946 end Test_Copy_Required
;
2948 -- Start of processing for No_Secondary_Stack_Case
2951 -- No copy needed if result is from a function call.
2952 -- In this case the result is already being returned by
2953 -- reference with the stack pointer depressed.
2955 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2956 -- the copy for array types if the constrained status of the
2957 -- target type is different from that of the expression.
2959 if Requires_Transient_Scope
(T
)
2961 (not Is_Array_Type
(T
)
2962 or else Is_Constrained
(T
) = Is_Constrained
(Return_Type
)
2963 or else Controlled_Type
(T
))
2964 and then Nkind
(Exp
) = N_Function_Call
2968 -- We always need a local copy for a controlled type, since
2969 -- we are required to finalize the local value before return.
2970 -- The copy will automatically include the required finalize.
2971 -- Moreover, gigi cannot make this copy, since we need special
2972 -- processing to ensure proper behavior for finalization.
2974 -- Note: the reason we are returning with a depressed stack
2975 -- pointer in the controlled case (even if the type involved
2976 -- is constrained) is that we must make a local copy to deal
2977 -- properly with the requirement that the local result be
2980 elsif Controlled_Type
(Utyp
) then
2982 Make_Defining_Identifier
(Loc
,
2983 Chars
=> New_Internal_Name
('R'));
2985 -- Build declaration to do the copy, and insert it, setting
2986 -- Assignment_OK, because we may be copying a limited type.
2987 -- In addition we set the special flag to inhibit finalize
2988 -- attachment if this is a controlled type (since this attach
2989 -- must be done by the caller, otherwise if we attach it here
2990 -- we will finalize the returned result prematurely).
2993 Make_Object_Declaration
(Loc
,
2994 Defining_Identifier
=> Copy_Ent
,
2995 Object_Definition
=> New_Occurrence_Of
(Return_Type
, Loc
),
2996 Expression
=> Relocate_Node
(Exp
));
2998 Set_Assignment_OK
(Decl
);
2999 Set_Delay_Finalize_Attach
(Decl
);
3000 Insert_Action
(N
, Decl
);
3002 -- Now the actual return uses the copied value
3004 Rewrite
(Exp
, New_Occurrence_Of
(Copy_Ent
, Loc
));
3005 Analyze_And_Resolve
(Exp
, Return_Type
);
3007 -- Since we have made the copy, gigi does not have to, so
3008 -- we set the By_Ref flag to prevent another copy being made.
3012 -- Non-controlled cases
3015 Test_Copy_Required
(Exp
);
3017 -- If a local copy is required, then gigi will make the
3018 -- copy, otherwise, we can return the result directly,
3019 -- so set By_Ref to suppress the gigi copy.
3021 if not Local_Copy_Required
then
3025 end No_Secondary_Stack_Case
;
3027 -- Here if secondary stack is used
3030 -- Make sure that no surrounding block will reclaim the
3031 -- secondary-stack on which we are going to put the result.
3032 -- Not only may this introduce secondary stack leaks but worse,
3033 -- if the reclamation is done too early, then the result we are
3034 -- returning may get clobbered. See example in 7417-003.
3037 S
: Entity_Id
:= Current_Scope
;
3040 while Ekind
(S
) = E_Block
or else Ekind
(S
) = E_Loop
loop
3041 Set_Sec_Stack_Needed_For_Return
(S
, True);
3042 S
:= Enclosing_Dynamic_Scope
(S
);
3046 -- Optimize the case where the result is a function call. In this
3047 -- case either the result is already on the secondary stack, or is
3048 -- already being returned with the stack pointer depressed and no
3049 -- further processing is required except to set the By_Ref flag to
3050 -- ensure that gigi does not attempt an extra unnecessary copy.
3051 -- (actually not just unnecessary but harmfully wrong in the case
3052 -- of a controlled type, where gigi does not know how to do a copy).
3053 -- To make up for a gcc 2.8.1 deficiency (???), we perform
3054 -- the copy for array types if the constrained status of the
3055 -- target type is different from that of the expression.
3057 if Requires_Transient_Scope
(T
)
3059 (not Is_Array_Type
(T
)
3060 or else Is_Constrained
(T
) = Is_Constrained
(Return_Type
)
3061 or else Controlled_Type
(T
))
3062 and then Nkind
(Exp
) = N_Function_Call
3066 -- For controlled types, do the allocation on the sec-stack
3067 -- manually in order to call adjust at the right time
3068 -- type Anon1 is access Return_Type;
3069 -- for Anon1'Storage_pool use ss_pool;
3070 -- Anon2 : anon1 := new Return_Type'(expr);
3071 -- return Anon2.all;
3073 elsif Controlled_Type
(Utyp
) then
3075 Loc
: constant Source_Ptr
:= Sloc
(N
);
3076 Temp
: constant Entity_Id
:=
3077 Make_Defining_Identifier
(Loc
,
3078 Chars
=> New_Internal_Name
('R'));
3079 Acc_Typ
: constant Entity_Id
:=
3080 Make_Defining_Identifier
(Loc
,
3081 Chars
=> New_Internal_Name
('A'));
3082 Alloc_Node
: Node_Id
;
3085 Set_Ekind
(Acc_Typ
, E_Access_Type
);
3087 Set_Associated_Storage_Pool
(Acc_Typ
, RTE
(RE_SS_Pool
));
3090 Make_Allocator
(Loc
,
3092 Make_Qualified_Expression
(Loc
,
3093 Subtype_Mark
=> New_Reference_To
(Etype
(Exp
), Loc
),
3094 Expression
=> Relocate_Node
(Exp
)));
3096 Insert_List_Before_And_Analyze
(N
, New_List
(
3097 Make_Full_Type_Declaration
(Loc
,
3098 Defining_Identifier
=> Acc_Typ
,
3100 Make_Access_To_Object_Definition
(Loc
,
3101 Subtype_Indication
=>
3102 New_Reference_To
(Return_Type
, Loc
))),
3104 Make_Object_Declaration
(Loc
,
3105 Defining_Identifier
=> Temp
,
3106 Object_Definition
=> New_Reference_To
(Acc_Typ
, Loc
),
3107 Expression
=> Alloc_Node
)));
3110 Make_Explicit_Dereference
(Loc
,
3111 Prefix
=> New_Reference_To
(Temp
, Loc
)));
3113 Analyze_And_Resolve
(Exp
, Return_Type
);
3116 -- Otherwise use the gigi mechanism to allocate result on the
3120 Set_Storage_Pool
(N
, RTE
(RE_SS_Pool
));
3122 -- If we are generating code for the Java VM do not use
3123 -- SS_Allocate since everything is heap-allocated anyway.
3126 Set_Procedure_To_Call
(N
, RTE
(RE_SS_Allocate
));
3132 when RE_Not_Available
=>
3134 end Expand_N_Return_Statement
;
3136 ------------------------------
3137 -- Make_Tag_Ctrl_Assignment --
3138 ------------------------------
3140 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
is
3141 Loc
: constant Source_Ptr
:= Sloc
(N
);
3142 L
: constant Node_Id
:= Name
(N
);
3143 T
: constant Entity_Id
:= Underlying_Type
(Etype
(L
));
3145 Ctrl_Act
: constant Boolean := Controlled_Type
(T
)
3146 and then not No_Ctrl_Actions
(N
);
3148 Save_Tag
: constant Boolean := Is_Tagged_Type
(T
)
3149 and then not No_Ctrl_Actions
(N
)
3150 and then not Java_VM
;
3151 -- Tags are not saved and restored when Java_VM because JVM tags
3152 -- are represented implicitly in objects.
3155 Tag_Tmp
: Entity_Id
;
3160 -- Finalize the target of the assignment when controlled.
3161 -- We have two exceptions here:
3163 -- 1. If we are in an init proc since it is an initialization
3164 -- more than an assignment
3166 -- 2. If the left-hand side is a temporary that was not initialized
3167 -- (or the parent part of a temporary since it is the case in
3168 -- extension aggregates). Such a temporary does not come from
3169 -- source. We must examine the original node for the prefix, because
3170 -- it may be a component of an entry formal, in which case it has
3171 -- been rewritten and does not appear to come from source either.
3173 -- Case of init proc
3175 if not Ctrl_Act
then
3178 -- The left hand side is an uninitialized temporary
3180 elsif Nkind
(L
) = N_Type_Conversion
3181 and then Is_Entity_Name
(Expression
(L
))
3182 and then No_Initialization
(Parent
(Entity
(Expression
(L
))))
3186 Append_List_To
(Res
,
3188 Ref
=> Duplicate_Subexpr_No_Checks
(L
),
3190 With_Detach
=> New_Reference_To
(Standard_False
, Loc
)));
3193 -- Save the Tag in a local variable Tag_Tmp
3197 Make_Defining_Identifier
(Loc
, New_Internal_Name
('A'));
3200 Make_Object_Declaration
(Loc
,
3201 Defining_Identifier
=> Tag_Tmp
,
3202 Object_Definition
=> New_Reference_To
(RTE
(RE_Tag
), Loc
),
3204 Make_Selected_Component
(Loc
,
3205 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
3206 Selector_Name
=> New_Reference_To
(First_Tag_Component
(T
),
3209 -- Otherwise Tag_Tmp not used
3215 -- Processing for controlled types and types with controlled components
3217 -- Variables of such types contain pointers used to chain them in
3218 -- finalization lists, in addition to user data. These pointers are
3219 -- specific to each object of the type, not to the value being assigned.
3220 -- Thus they need to be left intact during the assignment. We achieve
3221 -- this by constructing a Storage_Array subtype, and by overlaying
3222 -- objects of this type on the source and target of the assignment.
3223 -- The assignment is then rewritten to assignments of slices of these
3224 -- arrays, copying the user data, and leaving the pointers untouched.
3227 Controlled_Actions
: declare
3229 -- A reference to the Prev component of the record controller
3231 First_After_Root
: Node_Id
:= Empty
;
3232 -- Index of first byte to be copied (used to skip
3233 -- Root_Controlled in controlled objects).
3235 Last_Before_Hole
: Node_Id
:= Empty
;
3236 -- Index of last byte to be copied before outermost record
3239 Hole_Length
: Node_Id
:= Empty
;
3240 -- Length of record controller data (Prev and Next pointers)
3242 First_After_Hole
: Node_Id
:= Empty
;
3243 -- Index of first byte to be copied after outermost record
3246 Expr
, Source_Size
: Node_Id
;
3247 Source_Actual_Subtype
: Entity_Id
;
3248 -- Used for computation of the size of the data to be copied
3250 Range_Type
: Entity_Id
;
3251 Opaque_Type
: Entity_Id
;
3253 function Build_Slice
3256 Hi
: Node_Id
) return Node_Id
;
3257 -- Build and return a slice of an array of type S overlaid
3258 -- on object Rec, with bounds specified by Lo and Hi. If either
3259 -- bound is empty, a default of S'First (respectively S'Last)
3266 function Build_Slice
3269 Hi
: Node_Id
) return Node_Id
3274 Opaque
: constant Node_Id
:=
3275 Unchecked_Convert_To
(Opaque_Type
,
3276 Make_Attribute_Reference
(Loc
,
3278 Attribute_Name
=> Name_Address
));
3279 -- Access value designating an opaque storage array of
3280 -- type S overlaid on record Rec.
3283 -- Compute slice bounds using S'First (1) and S'Last
3284 -- as default values when not specified by the caller.
3287 Lo_Bound
:= Make_Integer_Literal
(Loc
, 1);
3293 Hi_Bound
:= Make_Attribute_Reference
(Loc
,
3294 Prefix
=> New_Occurrence_Of
(Range_Type
, Loc
),
3295 Attribute_Name
=> Name_Last
);
3300 return Make_Slice
(Loc
,
3303 Discrete_Range
=> Make_Range
(Loc
,
3304 Lo_Bound
, Hi_Bound
));
3307 -- Start of processing for Controlled_Actions
3310 -- Create a constrained subtype of Storage_Array whose size
3311 -- corresponds to the value being assigned.
3313 -- subtype G is Storage_Offset range
3314 -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit
3316 Expr
:= Duplicate_Subexpr_No_Checks
(Expression
(N
));
3318 if Nkind
(Expr
) = N_Qualified_Expression
then
3319 Expr
:= Expression
(Expr
);
3322 Source_Actual_Subtype
:= Etype
(Expr
);
3324 if Has_Discriminants
(Source_Actual_Subtype
)
3325 and then not Is_Constrained
(Source_Actual_Subtype
)
3328 Build_Actual_Subtype
(Source_Actual_Subtype
, Expr
));
3329 Source_Actual_Subtype
:= Defining_Identifier
(Last
(Res
));
3335 Make_Attribute_Reference
(Loc
,
3337 New_Occurrence_Of
(Source_Actual_Subtype
, Loc
),
3341 Make_Integer_Literal
(Loc
,
3342 System_Storage_Unit
- 1));
3344 Make_Op_Divide
(Loc
,
3345 Left_Opnd
=> Source_Size
,
3347 Make_Integer_Literal
(Loc
,
3348 Intval
=> System_Storage_Unit
));
3351 Make_Defining_Identifier
(Loc
,
3352 New_Internal_Name
('G'));
3355 Make_Subtype_Declaration
(Loc
,
3356 Defining_Identifier
=> Range_Type
,
3357 Subtype_Indication
=>
3358 Make_Subtype_Indication
(Loc
,
3360 New_Reference_To
(RTE
(RE_Storage_Offset
), Loc
),
3361 Constraint
=> Make_Range_Constraint
(Loc
,
3364 Low_Bound
=> Make_Integer_Literal
(Loc
, 1),
3365 High_Bound
=> Source_Size
)))));
3367 -- subtype S is Storage_Array (G)
3370 Make_Subtype_Declaration
(Loc
,
3371 Defining_Identifier
=>
3372 Make_Defining_Identifier
(Loc
,
3373 New_Internal_Name
('S')),
3374 Subtype_Indication
=>
3375 Make_Subtype_Indication
(Loc
,
3377 New_Reference_To
(RTE
(RE_Storage_Array
), Loc
),
3379 Make_Index_Or_Discriminant_Constraint
(Loc
,
3381 New_List
(New_Reference_To
(Range_Type
, Loc
))))));
3383 -- type A is access S
3386 Make_Defining_Identifier
(Loc
,
3387 Chars
=> New_Internal_Name
('A'));
3390 Make_Full_Type_Declaration
(Loc
,
3391 Defining_Identifier
=> Opaque_Type
,
3393 Make_Access_To_Object_Definition
(Loc
,
3394 Subtype_Indication
=>
3396 Defining_Identifier
(Last
(Res
)), Loc
))));
3398 -- Generate appropriate slice assignments
3400 First_After_Root
:= Make_Integer_Literal
(Loc
, 1);
3402 -- For the case of a controlled object, skip the
3403 -- Root_Controlled part.
3405 if Is_Controlled
(T
) then
3409 Make_Op_Divide
(Loc
,
3410 Make_Attribute_Reference
(Loc
,
3412 New_Occurrence_Of
(RTE
(RE_Root_Controlled
), Loc
),
3413 Attribute_Name
=> Name_Size
),
3414 Make_Integer_Literal
(Loc
, System_Storage_Unit
)));
3417 -- For the case of a record with controlled components, skip
3418 -- the Prev and Next components of the record controller.
3419 -- These components constitute a 'hole' in the middle of the
3420 -- data to be copied.
3422 if Has_Controlled_Component
(T
) then
3424 Make_Selected_Component
(Loc
,
3426 Make_Selected_Component
(Loc
,
3427 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
3429 New_Reference_To
(Controller_Component
(T
), Loc
)),
3430 Selector_Name
=> Make_Identifier
(Loc
, Name_Prev
));
3432 -- Last index before hole: determined by position of
3433 -- the _Controller.Prev component.
3436 Make_Defining_Identifier
(Loc
,
3437 New_Internal_Name
('L'));
3440 Make_Object_Declaration
(Loc
,
3441 Defining_Identifier
=> Last_Before_Hole
,
3442 Object_Definition
=> New_Occurrence_Of
(
3443 RTE
(RE_Storage_Offset
), Loc
),
3444 Constant_Present
=> True,
3445 Expression
=> Make_Op_Add
(Loc
,
3446 Make_Attribute_Reference
(Loc
,
3448 Attribute_Name
=> Name_Position
),
3449 Make_Attribute_Reference
(Loc
,
3450 Prefix
=> New_Copy_Tree
(Prefix
(Prev_Ref
)),
3451 Attribute_Name
=> Name_Position
))));
3453 -- Hole length: size of the Prev and Next components
3456 Make_Op_Multiply
(Loc
,
3457 Left_Opnd
=> Make_Integer_Literal
(Loc
, Uint_2
),
3459 Make_Op_Divide
(Loc
,
3461 Make_Attribute_Reference
(Loc
,
3462 Prefix
=> New_Copy_Tree
(Prev_Ref
),
3463 Attribute_Name
=> Name_Size
),
3465 Make_Integer_Literal
(Loc
,
3466 Intval
=> System_Storage_Unit
)));
3468 -- First index after hole
3471 Make_Defining_Identifier
(Loc
,
3472 New_Internal_Name
('F'));
3475 Make_Object_Declaration
(Loc
,
3476 Defining_Identifier
=> First_After_Hole
,
3477 Object_Definition
=> New_Occurrence_Of
(
3478 RTE
(RE_Storage_Offset
), Loc
),
3479 Constant_Present
=> True,
3485 New_Occurrence_Of
(Last_Before_Hole
, Loc
),
3486 Right_Opnd
=> Hole_Length
),
3487 Right_Opnd
=> Make_Integer_Literal
(Loc
, 1))));
3489 Last_Before_Hole
:= New_Occurrence_Of
(Last_Before_Hole
, Loc
);
3490 First_After_Hole
:= New_Occurrence_Of
(First_After_Hole
, Loc
);
3493 -- Assign the first slice (possibly skipping Root_Controlled,
3494 -- up to the beginning of the record controller if present,
3495 -- up to the end of the object if not).
3497 Append_To
(Res
, Make_Assignment_Statement
(Loc
,
3498 Name
=> Build_Slice
(
3499 Rec
=> Duplicate_Subexpr_No_Checks
(L
),
3500 Lo
=> First_After_Root
,
3501 Hi
=> Last_Before_Hole
),
3503 Expression
=> Build_Slice
(
3504 Rec
=> Expression
(N
),
3505 Lo
=> First_After_Root
,
3506 Hi
=> New_Copy_Tree
(Last_Before_Hole
))));
3508 if Present
(First_After_Hole
) then
3510 -- If a record controller is present, copy the second slice,
3511 -- from right after the _Controller.Next component up to the
3512 -- end of the object.
3514 Append_To
(Res
, Make_Assignment_Statement
(Loc
,
3515 Name
=> Build_Slice
(
3516 Rec
=> Duplicate_Subexpr_No_Checks
(L
),
3517 Lo
=> First_After_Hole
,
3519 Expression
=> Build_Slice
(
3520 Rec
=> Duplicate_Subexpr_No_Checks
(Expression
(N
)),
3521 Lo
=> New_Copy_Tree
(First_After_Hole
),
3524 end Controlled_Actions
;
3527 Append_To
(Res
, Relocate_Node
(N
));
3534 Make_Assignment_Statement
(Loc
,
3536 Make_Selected_Component
(Loc
,
3537 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
3538 Selector_Name
=> New_Reference_To
(First_Tag_Component
(T
),
3540 Expression
=> New_Reference_To
(Tag_Tmp
, Loc
)));
3543 -- Adjust the target after the assignment when controlled (not in the
3544 -- init proc since it is an initialization more than an assignment).
3547 Append_List_To
(Res
,
3549 Ref
=> Duplicate_Subexpr_Move_Checks
(L
),
3551 Flist_Ref
=> New_Reference_To
(RTE
(RE_Global_Final_List
), Loc
),
3552 With_Attach
=> Make_Integer_Literal
(Loc
, 0)));
3558 -- Could use comment here ???
3560 when RE_Not_Available
=>
3562 end Make_Tag_Ctrl_Assignment
;
3564 ------------------------------------
3565 -- Possible_Bit_Aligned_Component --
3566 ------------------------------------
3568 function Possible_Bit_Aligned_Component
(N
: Node_Id
) return Boolean is
3572 -- Case of indexed component
3574 when N_Indexed_Component
=>
3576 P
: constant Node_Id
:= Prefix
(N
);
3577 Ptyp
: constant Entity_Id
:= Etype
(P
);
3580 -- If we know the component size and it is less than 64, then
3581 -- we are definitely OK. The back end always does assignment
3582 -- of misaligned small objects correctly.
3584 if Known_Static_Component_Size
(Ptyp
)
3585 and then Component_Size
(Ptyp
) <= 64
3589 -- Otherwise, we need to test the prefix, to see if we are
3590 -- indexing from a possibly unaligned component.
3593 return Possible_Bit_Aligned_Component
(P
);
3597 -- Case of selected component
3599 when N_Selected_Component
=>
3601 P
: constant Node_Id
:= Prefix
(N
);
3602 Comp
: constant Entity_Id
:= Entity
(Selector_Name
(N
));
3605 -- If there is no component clause, then we are in the clear
3606 -- since the back end will never misalign a large component
3607 -- unless it is forced to do so. In the clear means we need
3608 -- only the recursive test on the prefix.
3610 if Component_May_Be_Bit_Aligned
(Comp
) then
3613 return Possible_Bit_Aligned_Component
(P
);
3617 -- If we have neither a record nor array component, it means that
3618 -- we have fallen off the top testing prefixes recursively, and
3619 -- we now have a stand alone object, where we don't have a problem
3625 end Possible_Bit_Aligned_Component
;