1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2003, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 with Atree
; use Atree
;
28 with Checks
; use Checks
;
29 with Einfo
; use Einfo
;
30 with Exp_Aggr
; use Exp_Aggr
;
31 with Exp_Ch7
; use Exp_Ch7
;
32 with Exp_Ch11
; use Exp_Ch11
;
33 with Exp_Dbug
; use Exp_Dbug
;
34 with Exp_Pakd
; use Exp_Pakd
;
35 with Exp_Util
; use Exp_Util
;
36 with Hostparm
; use Hostparm
;
37 with Nlists
; use Nlists
;
38 with Nmake
; use Nmake
;
40 with Restrict
; use Restrict
;
41 with Rtsfind
; use Rtsfind
;
42 with Sinfo
; use Sinfo
;
44 with Sem_Ch8
; use Sem_Ch8
;
45 with Sem_Ch13
; use Sem_Ch13
;
46 with Sem_Eval
; use Sem_Eval
;
47 with Sem_Res
; use Sem_Res
;
48 with Sem_Util
; use Sem_Util
;
49 with Snames
; use Snames
;
50 with Stand
; use Stand
;
51 with Tbuild
; use Tbuild
;
52 with Ttypes
; use Ttypes
;
53 with Uintp
; use Uintp
;
54 with Validsw
; use Validsw
;
56 package body Exp_Ch5
is
58 function Change_Of_Representation
(N
: Node_Id
) return Boolean;
59 -- Determine if the right hand side of the assignment N is a type
60 -- conversion which requires a change of representation. Called
61 -- only for the array and record cases.
63 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
);
64 -- N is an assignment which assigns an array value. This routine process
65 -- the various special cases and checks required for such assignments,
66 -- including change of representation. Rhs is normally simply the right
67 -- hand side of the assignment, except that if the right hand side is
68 -- a type conversion or a qualified expression, then the Rhs is the
69 -- actual expression inside any such type conversions or qualifications.
71 function Expand_Assign_Array_Loop
80 -- N is an assignment statement which assigns an array value. This routine
81 -- expands the assignment into a loop (or nested loops for the case of a
82 -- multi-dimensional array) to do the assignment component by component.
83 -- Larray and Rarray are the entities of the actual arrays on the left
84 -- hand and right hand sides. L_Type and R_Type are the types of these
85 -- arrays (which may not be the same, due to either sliding, or to a
86 -- change of representation case). Ndim is the number of dimensions and
87 -- the parameter Rev indicates if the loops run normally (Rev = False),
88 -- or reversed (Rev = True). The value returned is the constructed
89 -- loop statement. Auxiliary declarations are inserted before node N
90 -- using the standard Insert_Actions mechanism.
92 procedure Expand_Assign_Record
(N
: Node_Id
);
93 -- N is an assignment of a non-tagged record value. This routine handles
94 -- the case where the assignment must be made component by component,
95 -- either because the target is not byte aligned, or there is a change
98 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
;
99 -- Generate the necessary code for controlled and Tagged assignment,
100 -- that is to say, finalization of the target before, adjustement of
101 -- the target after and save and restore of the tag and finalization
102 -- pointers which are not 'part of the value' and must not be changed
103 -- upon assignment. N is the original Assignment node.
105 function Possible_Bit_Aligned_Component
(N
: Node_Id
) return Boolean;
106 -- This function is used in processing the assignment of a record or
107 -- indexed component. The back end can handle such assignments fine
108 -- if the objects involved are small (64-bits or less) records or
109 -- scalar items (including bit-packed arrays represented with modular
110 -- types) or are both aligned on a byte boundary (starting on a byte
111 -- boundary, and occupying an integral number of bytes).
113 -- However, problems arise for records larger than 64 bits, or for
114 -- arrays (other than bit-packed arrays represented with a modular
115 -- type) if the component starts on a non-byte boundary, or does
116 -- not occupy an integral number of bytes (i.e. there are some bits
117 -- possibly shared with fields at the start or beginning of the
118 -- component). The back end cannot handle loading and storing such
119 -- components in a single operation.
121 -- This function is used to detect the troublesome situation. it is
122 -- conservative in the sense that it produces True unless it knows
123 -- for sure that the component is safe (as outlined in the first
124 -- paragraph above). The code generation for record and array
125 -- assignment checks for trouble using this function, and if so
126 -- the assignment is generated component-wise, which the back end
127 -- is required to handle correctly.
129 -- Note that in GNAT 3, the back end will reject such components
130 -- anyway, so the hard work in checking for this case is wasted
131 -- in GNAT 3, but it's harmless, so it is easier to do it in
132 -- all cases, rather than conditionalize it in GNAT 5 or beyond.
134 ------------------------------
135 -- Change_Of_Representation --
136 ------------------------------
138 function Change_Of_Representation
(N
: Node_Id
) return Boolean is
139 Rhs
: constant Node_Id
:= Expression
(N
);
142 Nkind
(Rhs
) = N_Type_Conversion
144 not Same_Representation
(Etype
(Rhs
), Etype
(Expression
(Rhs
)));
145 end Change_Of_Representation
;
147 -------------------------
148 -- Expand_Assign_Array --
149 -------------------------
151 -- There are two issues here. First, do we let Gigi do a block move, or
152 -- do we expand out into a loop? Second, we need to set the two flags
153 -- Forwards_OK and Backwards_OK which show whether the block move (or
154 -- corresponding loops) can be legitimately done in a forwards (low to
155 -- high) or backwards (high to low) manner.
157 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
) is
158 Loc
: constant Source_Ptr
:= Sloc
(N
);
160 Lhs
: constant Node_Id
:= Name
(N
);
162 Act_Lhs
: constant Node_Id
:= Get_Referenced_Object
(Lhs
);
163 Act_Rhs
: Node_Id
:= Get_Referenced_Object
(Rhs
);
165 L_Type
: constant Entity_Id
:=
166 Underlying_Type
(Get_Actual_Subtype
(Act_Lhs
));
167 R_Type
: Entity_Id
:=
168 Underlying_Type
(Get_Actual_Subtype
(Act_Rhs
));
170 L_Slice
: constant Boolean := Nkind
(Act_Lhs
) = N_Slice
;
171 R_Slice
: constant Boolean := Nkind
(Act_Rhs
) = N_Slice
;
173 Crep
: constant Boolean := Change_Of_Representation
(N
);
178 Ndim
: constant Pos
:= Number_Dimensions
(L_Type
);
180 Loop_Required
: Boolean := False;
181 -- This switch is set to True if the array move must be done using
182 -- an explicit front end generated loop.
184 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean;
185 -- Test if Exp is a reference to an array whose declaration has
186 -- an address clause, or it is a slice of such an array.
188 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean;
189 -- Test if Exp is a reference to an array which is either a formal
190 -- parameter or a slice of a formal parameter. These are the cases
191 -- where hidden aliasing can occur.
193 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean;
194 -- Determine if Exp is a reference to an array variable which is other
195 -- than an object defined in the current scope, or a slice of such
196 -- an object. Such objects can be aliased to parameters (unlike local
197 -- array references).
199 function Possible_Unaligned_Slice
(Arg
: Node_Id
) return Boolean;
200 -- Returns True if Arg (either the left or right hand side of the
201 -- assignment) is a slice that could be unaligned wrt the array type.
202 -- This is true if Arg is a component of a packed record, or is
203 -- a record component to which a component clause applies. This
204 -- is a little pessimistic, but the result of an unnecessary
205 -- decision that something is possibly unaligned is only to
206 -- generate a front end loop, which is not so terrible.
207 -- It would really be better if backend handled this ???
209 ------------------------
210 -- Has_Address_Clause --
211 ------------------------
213 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean is
216 (Is_Entity_Name
(Exp
) and then
217 Present
(Address_Clause
(Entity
(Exp
))))
219 (Nkind
(Exp
) = N_Slice
and then Has_Address_Clause
(Prefix
(Exp
)));
220 end Has_Address_Clause
;
222 ---------------------
223 -- Is_Formal_Array --
224 ---------------------
226 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean is
229 (Is_Entity_Name
(Exp
) and then Is_Formal
(Entity
(Exp
)))
231 (Nkind
(Exp
) = N_Slice
and then Is_Formal_Array
(Prefix
(Exp
)));
234 ------------------------
235 -- Is_Non_Local_Array --
236 ------------------------
238 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean is
240 return (Is_Entity_Name
(Exp
)
241 and then Scope
(Entity
(Exp
)) /= Current_Scope
)
242 or else (Nkind
(Exp
) = N_Slice
243 and then Is_Non_Local_Array
(Prefix
(Exp
)));
244 end Is_Non_Local_Array
;
246 ------------------------------
247 -- Possible_Unaligned_Slice --
248 ------------------------------
250 function Possible_Unaligned_Slice
(Arg
: Node_Id
) return Boolean is
252 -- No issue if this is not a slice, or else strict alignment
253 -- is not required in any case.
255 if Nkind
(Arg
) /= N_Slice
256 or else not Target_Strict_Alignment
261 -- No issue if the component type is a byte or byte aligned
264 Array_Typ
: constant Entity_Id
:= Etype
(Arg
);
265 Comp_Typ
: constant Entity_Id
:= Component_Type
(Array_Typ
);
266 Pref
: constant Node_Id
:= Prefix
(Arg
);
269 if Known_Alignment
(Array_Typ
) then
270 if Alignment
(Array_Typ
) = 1 then
274 elsif Known_Component_Size
(Array_Typ
) then
275 if Component_Size
(Array_Typ
) = 1 then
279 elsif Known_Esize
(Comp_Typ
) then
280 if Esize
(Comp_Typ
) <= System_Storage_Unit
then
285 -- No issue if this is not a selected component
287 if Nkind
(Pref
) /= N_Selected_Component
then
291 -- Else we test for a possibly unaligned component
294 Is_Packed
(Etype
(Pref
))
296 Present
(Component_Clause
(Entity
(Selector_Name
(Pref
))));
298 end Possible_Unaligned_Slice
;
300 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
302 Lhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Lhs
);
303 Rhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Rhs
);
305 Lhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Lhs
);
306 Rhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Rhs
);
308 -- Start of processing for Expand_Assign_Array
311 -- Deal with length check, note that the length check is done with
312 -- respect to the right hand side as given, not a possible underlying
313 -- renamed object, since this would generate incorrect extra checks.
315 Apply_Length_Check
(Rhs
, L_Type
);
317 -- We start by assuming that the move can be done in either
318 -- direction, i.e. that the two sides are completely disjoint.
320 Set_Forwards_OK
(N
, True);
321 Set_Backwards_OK
(N
, True);
323 -- Normally it is only the slice case that can lead to overlap,
324 -- and explicit checks for slices are made below. But there is
325 -- one case where the slice can be implicit and invisible to us
326 -- and that is the case where we have a one dimensional array,
327 -- and either both operands are parameters, or one is a parameter
328 -- and the other is a global variable. In this case the parameter
329 -- could be a slice that overlaps with the other parameter.
331 -- Check for the case of slices requiring an explicit loop. Normally
332 -- it is only the explicit slice cases that bother us, but in the
333 -- case of one dimensional arrays, parameters can be slices that
334 -- are passed by reference, so we can have aliasing for assignments
335 -- from one parameter to another, or assignments between parameters
336 -- and nonlocal variables. However, if the array subtype is a
337 -- constrained first subtype in the parameter case, then we don't
338 -- have to worry about overlap, since slice assignments aren't
339 -- possible (other than for a slice denoting the whole array).
341 -- Note: overlap is never possible if there is a change of
342 -- representation, so we can exclude this case.
347 ((Lhs_Formal
and Rhs_Formal
)
349 (Lhs_Formal
and Rhs_Non_Local_Var
)
351 (Rhs_Formal
and Lhs_Non_Local_Var
))
353 (not Is_Constrained
(Etype
(Lhs
))
354 or else not Is_First_Subtype
(Etype
(Lhs
)))
356 -- In the case of compiling for the Java Virtual Machine,
357 -- slices are always passed by making a copy, so we don't
358 -- have to worry about overlap. We also want to prevent
359 -- generation of "<" comparisons for array addresses,
360 -- since that's a meaningless operation on the JVM.
364 Set_Forwards_OK
(N
, False);
365 Set_Backwards_OK
(N
, False);
367 -- Note: the bit-packed case is not worrisome here, since if
368 -- we have a slice passed as a parameter, it is always aligned
369 -- on a byte boundary, and if there are no explicit slices, the
370 -- assignment can be performed directly.
373 -- We certainly must use a loop for change of representation
374 -- and also we use the operand of the conversion on the right
375 -- hand side as the effective right hand side (the component
376 -- types must match in this situation).
379 Act_Rhs
:= Get_Referenced_Object
(Rhs
);
380 R_Type
:= Get_Actual_Subtype
(Act_Rhs
);
381 Loop_Required
:= True;
383 -- We require a loop if the left side is possibly bit unaligned
385 elsif Possible_Bit_Aligned_Component
(Lhs
)
387 Possible_Bit_Aligned_Component
(Rhs
)
389 Loop_Required
:= True;
391 -- Arrays with controlled components are expanded into a loop
392 -- to force calls to adjust at the component level.
394 elsif Has_Controlled_Component
(L_Type
) then
395 Loop_Required
:= True;
397 -- Case where no slice is involved
399 elsif not L_Slice
and not R_Slice
then
401 -- The following code deals with the case of unconstrained bit
402 -- packed arrays. The problem is that the template for such
403 -- arrays contains the bounds of the actual source level array,
405 -- But the copy of an entire array requires the bounds of the
406 -- underlying array. It would be nice if the back end could take
407 -- care of this, but right now it does not know how, so if we
408 -- have such a type, then we expand out into a loop, which is
409 -- inefficient but works correctly. If we don't do this, we
410 -- get the wrong length computed for the array to be moved.
411 -- The two cases we need to worry about are:
413 -- Explicit deference of an unconstrained packed array type as
414 -- in the following example:
417 -- type BITS is array(INTEGER range <>) of BOOLEAN;
418 -- pragma PACK(BITS);
419 -- type A is access BITS;
422 -- P1 := new BITS (1 .. 65_535);
423 -- P2 := new BITS (1 .. 65_535);
427 -- A formal parameter reference with an unconstrained bit
428 -- array type is the other case we need to worry about (here
429 -- we assume the same BITS type declared above:
431 -- procedure Write_All (File : out BITS; Contents : in BITS);
433 -- File.Storage := Contents;
436 -- We expand to a loop in either of these two cases.
438 -- Question for future thought. Another potentially more efficient
439 -- approach would be to create the actual subtype, and then do an
440 -- unchecked conversion to this actual subtype ???
442 Check_Unconstrained_Bit_Packed_Array
: declare
444 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean;
445 -- Function to perform required test for the first case,
446 -- above (dereference of an unconstrained bit packed array)
448 -----------------------
449 -- Is_UBPA_Reference --
450 -----------------------
452 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean is
453 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Opnd
));
455 Des_Type
: Entity_Id
;
458 if Present
(Packed_Array_Type
(Typ
))
459 and then Is_Array_Type
(Packed_Array_Type
(Typ
))
460 and then not Is_Constrained
(Packed_Array_Type
(Typ
))
464 elsif Nkind
(Opnd
) = N_Explicit_Dereference
then
465 P_Type
:= Underlying_Type
(Etype
(Prefix
(Opnd
)));
467 if not Is_Access_Type
(P_Type
) then
471 Des_Type
:= Designated_Type
(P_Type
);
473 Is_Bit_Packed_Array
(Des_Type
)
474 and then not Is_Constrained
(Des_Type
);
480 end Is_UBPA_Reference
;
482 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
485 if Is_UBPA_Reference
(Lhs
)
487 Is_UBPA_Reference
(Rhs
)
489 Loop_Required
:= True;
491 -- Here if we do not have the case of a reference to a bit
492 -- packed unconstrained array case. In this case gigi can
493 -- most certainly handle the assignment if a forwards move
496 -- (could it handle the backwards case also???)
498 elsif Forwards_OK
(N
) then
501 end Check_Unconstrained_Bit_Packed_Array
;
503 -- Gigi can always handle the assignment if the right side is a string
504 -- literal (note that overlap is definitely impossible in this case).
505 -- If the type is packed, a string literal is always converted into a
506 -- aggregate, except in the case of a null slice, for which no aggregate
507 -- can be written. In that case, rewrite the assignment as a null
508 -- statement, a length check has already been emitted to verify that
509 -- the range of the left-hand side is empty.
511 elsif Nkind
(Rhs
) = N_String_Literal
then
512 if Ekind
(R_Type
) = E_String_Literal_Subtype
513 and then String_Literal_Length
(R_Type
) = 0
514 and then Is_Bit_Packed_Array
(L_Type
)
516 Rewrite
(N
, Make_Null_Statement
(Loc
));
522 -- If either operand is bit packed, then we need a loop, since we
523 -- can't be sure that the slice is byte aligned. Similarly, if either
524 -- operand is a possibly unaligned slice, then we need a loop (since
525 -- gigi cannot handle unaligned slices).
527 elsif Is_Bit_Packed_Array
(L_Type
)
528 or else Is_Bit_Packed_Array
(R_Type
)
529 or else Possible_Unaligned_Slice
(Lhs
)
530 or else Possible_Unaligned_Slice
(Rhs
)
532 Loop_Required
:= True;
534 -- If we are not bit-packed, and we have only one slice, then no
535 -- overlap is possible except in the parameter case, so we can let
536 -- gigi handle things.
538 elsif not (L_Slice
and R_Slice
) then
539 if Forwards_OK
(N
) then
544 -- Come here to compelete the analysis
546 -- Loop_Required: Set to True if we know that a loop is required
547 -- regardless of overlap considerations.
549 -- Forwards_OK: Set to False if we already know that a forwards
550 -- move is not safe, else set to True.
552 -- Backwards_OK: Set to False if we already know that a backwards
553 -- move is not safe, else set to True
555 -- Our task at this stage is to complete the overlap analysis, which
556 -- can result in possibly setting Forwards_OK or Backwards_OK to
557 -- False, and then generating the final code, either by deciding
558 -- that it is OK after all to let Gigi handle it, or by generating
559 -- appropriate code in the front end.
562 L_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(L_Type
));
563 R_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(R_Type
));
565 Left_Lo
: constant Node_Id
:= Type_Low_Bound
(L_Index_Typ
);
566 Left_Hi
: constant Node_Id
:= Type_High_Bound
(L_Index_Typ
);
567 Right_Lo
: constant Node_Id
:= Type_Low_Bound
(R_Index_Typ
);
568 Right_Hi
: constant Node_Id
:= Type_High_Bound
(R_Index_Typ
);
570 Act_L_Array
: Node_Id
;
571 Act_R_Array
: Node_Id
;
577 Cresult
: Compare_Result
;
580 -- Get the expressions for the arrays. If we are dealing with a
581 -- private type, then convert to the underlying type. We can do
582 -- direct assignments to an array that is a private type, but
583 -- we cannot assign to elements of the array without this extra
584 -- unchecked conversion.
586 if Nkind
(Act_Lhs
) = N_Slice
then
587 Larray
:= Prefix
(Act_Lhs
);
591 if Is_Private_Type
(Etype
(Larray
)) then
594 (Underlying_Type
(Etype
(Larray
)), Larray
);
598 if Nkind
(Act_Rhs
) = N_Slice
then
599 Rarray
:= Prefix
(Act_Rhs
);
603 if Is_Private_Type
(Etype
(Rarray
)) then
606 (Underlying_Type
(Etype
(Rarray
)), Rarray
);
610 -- If both sides are slices, we must figure out whether
611 -- it is safe to do the move in one direction or the other
612 -- It is always safe if there is a change of representation
613 -- since obviously two arrays with different representations
614 -- cannot possibly overlap.
616 if (not Crep
) and L_Slice
and R_Slice
then
617 Act_L_Array
:= Get_Referenced_Object
(Prefix
(Act_Lhs
));
618 Act_R_Array
:= Get_Referenced_Object
(Prefix
(Act_Rhs
));
620 -- If both left and right hand arrays are entity names, and
621 -- refer to different entities, then we know that the move
622 -- is safe (the two storage areas are completely disjoint).
624 if Is_Entity_Name
(Act_L_Array
)
625 and then Is_Entity_Name
(Act_R_Array
)
626 and then Entity
(Act_L_Array
) /= Entity
(Act_R_Array
)
630 -- Otherwise, we assume the worst, which is that the two
631 -- arrays are the same array. There is no need to check if
632 -- we know that is the case, because if we don't know it,
633 -- we still have to assume it!
635 -- Generally if the same array is involved, then we have
636 -- an overlapping case. We will have to really assume the
637 -- worst (i.e. set neither of the OK flags) unless we can
638 -- determine the lower or upper bounds at compile time and
642 Cresult
:= Compile_Time_Compare
(Left_Lo
, Right_Lo
);
644 if Cresult
= Unknown
then
645 Cresult
:= Compile_Time_Compare
(Left_Hi
, Right_Hi
);
649 when LT | LE | EQ
=> Set_Backwards_OK
(N
, False);
650 when GT | GE
=> Set_Forwards_OK
(N
, False);
651 when NE | Unknown
=> Set_Backwards_OK
(N
, False);
652 Set_Forwards_OK
(N
, False);
657 -- If after that analysis, Forwards_OK is still True, and
658 -- Loop_Required is False, meaning that we have not discovered
659 -- some non-overlap reason for requiring a loop, then we can
660 -- still let gigi handle it.
662 if not Loop_Required
then
663 if Forwards_OK
(N
) then
668 -- Here is where a memmove would be appropriate ???
672 -- At this stage we have to generate an explicit loop, and
673 -- we have the following cases:
675 -- Forwards_OK = True
677 -- Rnn : right_index := right_index'First;
678 -- for Lnn in left-index loop
679 -- left (Lnn) := right (Rnn);
680 -- Rnn := right_index'Succ (Rnn);
683 -- Note: the above code MUST be analyzed with checks off,
684 -- because otherwise the Succ could overflow. But in any
685 -- case this is more efficient!
687 -- Forwards_OK = False, Backwards_OK = True
689 -- Rnn : right_index := right_index'Last;
690 -- for Lnn in reverse left-index loop
691 -- left (Lnn) := right (Rnn);
692 -- Rnn := right_index'Pred (Rnn);
695 -- Note: the above code MUST be analyzed with checks off,
696 -- because otherwise the Pred could overflow. But in any
697 -- case this is more efficient!
699 -- Forwards_OK = Backwards_OK = False
701 -- This only happens if we have the same array on each side. It is
702 -- possible to create situations using overlays that violate this,
703 -- but we simply do not promise to get this "right" in this case.
705 -- There are two possible subcases. If the No_Implicit_Conditionals
706 -- restriction is set, then we generate the following code:
709 -- T : constant <operand-type> := rhs;
714 -- If implicit conditionals are permitted, then we generate:
716 -- if Left_Lo <= Right_Lo then
717 -- <code for Forwards_OK = True above>
719 -- <code for Backwards_OK = True above>
722 -- Cases where either Forwards_OK or Backwards_OK is true
724 if Forwards_OK
(N
) or else Backwards_OK
(N
) then
726 Expand_Assign_Array_Loop
727 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
728 Rev
=> not Forwards_OK
(N
)));
730 -- Case of both are false with No_Implicit_Conditionals
732 elsif Restrictions
(No_Implicit_Conditionals
) then
734 T
: constant Entity_Id
:= Make_Defining_Identifier
(Loc
,
739 Make_Block_Statement
(Loc
,
740 Declarations
=> New_List
(
741 Make_Object_Declaration
(Loc
,
742 Defining_Identifier
=> T
,
743 Constant_Present
=> True,
745 New_Occurrence_Of
(Etype
(Rhs
), Loc
),
746 Expression
=> Relocate_Node
(Rhs
))),
748 Handled_Statement_Sequence
=>
749 Make_Handled_Sequence_Of_Statements
(Loc
,
750 Statements
=> New_List
(
751 Make_Assignment_Statement
(Loc
,
752 Name
=> Relocate_Node
(Lhs
),
753 Expression
=> New_Occurrence_Of
(T
, Loc
))))));
756 -- Case of both are false with implicit conditionals allowed
759 -- Before we generate this code, we must ensure that the
760 -- left and right side array types are defined. They may
761 -- be itypes, and we cannot let them be defined inside the
762 -- if, since the first use in the then may not be executed.
764 Ensure_Defined
(L_Type
, N
);
765 Ensure_Defined
(R_Type
, N
);
767 -- We normally compare addresses to find out which way round
768 -- to do the loop, since this is realiable, and handles the
769 -- cases of parameters, conversions etc. But we can't do that
770 -- in the bit packed case or the Java VM case, because addresses
773 if not Is_Bit_Packed_Array
(L_Type
) and then not Java_VM
then
777 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
778 Make_Attribute_Reference
(Loc
,
780 Make_Indexed_Component
(Loc
,
782 Duplicate_Subexpr_Move_Checks
(Larray
, True),
783 Expressions
=> New_List
(
784 Make_Attribute_Reference
(Loc
,
788 Attribute_Name
=> Name_First
))),
789 Attribute_Name
=> Name_Address
)),
792 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
793 Make_Attribute_Reference
(Loc
,
795 Make_Indexed_Component
(Loc
,
797 Duplicate_Subexpr_Move_Checks
(Rarray
, True),
798 Expressions
=> New_List
(
799 Make_Attribute_Reference
(Loc
,
803 Attribute_Name
=> Name_First
))),
804 Attribute_Name
=> Name_Address
)));
806 -- For the bit packed and Java VM cases we use the bounds.
807 -- That's OK, because we don't have to worry about parameters,
808 -- since they cannot cause overlap. Perhaps we should worry
809 -- about weird slice conversions ???
812 -- Copy the bounds and reset the Analyzed flag, because the
813 -- bounds of the index type itself may be universal, and must
814 -- must be reaanalyzed to acquire the proper type for Gigi.
816 Cleft_Lo
:= New_Copy_Tree
(Left_Lo
);
817 Cright_Lo
:= New_Copy_Tree
(Right_Lo
);
818 Set_Analyzed
(Cleft_Lo
, False);
819 Set_Analyzed
(Cright_Lo
, False);
823 Left_Opnd
=> Cleft_Lo
,
824 Right_Opnd
=> Cright_Lo
);
828 Make_Implicit_If_Statement
(N
,
829 Condition
=> Condition
,
831 Then_Statements
=> New_List
(
832 Expand_Assign_Array_Loop
833 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
836 Else_Statements
=> New_List
(
837 Expand_Assign_Array_Loop
838 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
842 Analyze
(N
, Suppress
=> All_Checks
);
846 when RE_Not_Available
=>
848 end Expand_Assign_Array
;
850 ------------------------------
851 -- Expand_Assign_Array_Loop --
852 ------------------------------
854 -- The following is an example of the loop generated for the case of
855 -- a two-dimensional array:
860 -- for L1b in 1 .. 100 loop
864 -- for L3b in 1 .. 100 loop
865 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
866 -- R4b := Tm1X2'succ(R4b);
869 -- R2b := Tm1X1'succ(R2b);
873 -- Here Rev is False, and Tm1Xn are the subscript types for the right
874 -- hand side. The declarations of R2b and R4b are inserted before the
875 -- original assignment statement.
877 function Expand_Assign_Array_Loop
887 Loc
: constant Source_Ptr
:= Sloc
(N
);
889 Lnn
: array (1 .. Ndim
) of Entity_Id
;
890 Rnn
: array (1 .. Ndim
) of Entity_Id
;
891 -- Entities used as subscripts on left and right sides
893 L_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
894 R_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
895 -- Left and right index types
907 F_Or_L
:= Name_First
;
911 -- Setup index types and subscript entities
918 L_Index
:= First_Index
(L_Type
);
919 R_Index
:= First_Index
(R_Type
);
921 for J
in 1 .. Ndim
loop
923 Make_Defining_Identifier
(Loc
,
924 Chars
=> New_Internal_Name
('L'));
927 Make_Defining_Identifier
(Loc
,
928 Chars
=> New_Internal_Name
('R'));
930 L_Index_Type
(J
) := Etype
(L_Index
);
931 R_Index_Type
(J
) := Etype
(R_Index
);
933 Next_Index
(L_Index
);
934 Next_Index
(R_Index
);
938 -- Now construct the assignment statement
941 ExprL
: constant List_Id
:= New_List
;
942 ExprR
: constant List_Id
:= New_List
;
945 for J
in 1 .. Ndim
loop
946 Append_To
(ExprL
, New_Occurrence_Of
(Lnn
(J
), Loc
));
947 Append_To
(ExprR
, New_Occurrence_Of
(Rnn
(J
), Loc
));
951 Make_Assignment_Statement
(Loc
,
953 Make_Indexed_Component
(Loc
,
954 Prefix
=> Duplicate_Subexpr
(Larray
, Name_Req
=> True),
955 Expressions
=> ExprL
),
957 Make_Indexed_Component
(Loc
,
958 Prefix
=> Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
959 Expressions
=> ExprR
));
961 -- Propagate the No_Ctrl_Actions flag to individual assignments
963 Set_No_Ctrl_Actions
(Assign
, No_Ctrl_Actions
(N
));
966 -- Now construct the loop from the inside out, with the last subscript
967 -- varying most rapidly. Note that Assign is first the raw assignment
968 -- statement, and then subsequently the loop that wraps it up.
970 for J
in reverse 1 .. Ndim
loop
972 Make_Block_Statement
(Loc
,
973 Declarations
=> New_List
(
974 Make_Object_Declaration
(Loc
,
975 Defining_Identifier
=> Rnn
(J
),
977 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
979 Make_Attribute_Reference
(Loc
,
980 Prefix
=> New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
981 Attribute_Name
=> F_Or_L
))),
983 Handled_Statement_Sequence
=>
984 Make_Handled_Sequence_Of_Statements
(Loc
,
985 Statements
=> New_List
(
986 Make_Implicit_Loop_Statement
(N
,
988 Make_Iteration_Scheme
(Loc
,
989 Loop_Parameter_Specification
=>
990 Make_Loop_Parameter_Specification
(Loc
,
991 Defining_Identifier
=> Lnn
(J
),
992 Reverse_Present
=> Rev
,
993 Discrete_Subtype_Definition
=>
994 New_Reference_To
(L_Index_Type
(J
), Loc
))),
996 Statements
=> New_List
(
999 Make_Assignment_Statement
(Loc
,
1000 Name
=> New_Occurrence_Of
(Rnn
(J
), Loc
),
1002 Make_Attribute_Reference
(Loc
,
1004 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1005 Attribute_Name
=> S_Or_P
,
1006 Expressions
=> New_List
(
1007 New_Occurrence_Of
(Rnn
(J
), Loc
)))))))));
1011 end Expand_Assign_Array_Loop
;
1013 --------------------------
1014 -- Expand_Assign_Record --
1015 --------------------------
1017 -- The only processing required is in the change of representation
1018 -- case, where we must expand the assignment to a series of field
1019 -- by field assignments.
1021 procedure Expand_Assign_Record
(N
: Node_Id
) is
1022 Lhs
: constant Node_Id
:= Name
(N
);
1023 Rhs
: Node_Id
:= Expression
(N
);
1026 -- If change of representation, then extract the real right hand
1027 -- side from the type conversion, and proceed with component-wise
1028 -- assignment, since the two types are not the same as far as the
1029 -- back end is concerned.
1031 if Change_Of_Representation
(N
) then
1032 Rhs
:= Expression
(Rhs
);
1034 -- If this may be a case of a large bit aligned component, then
1035 -- proceed with component-wise assignment, to avoid possible
1036 -- clobbering of other components sharing bits in the first or
1037 -- last byte of the component to be assigned.
1039 elsif Possible_Bit_Aligned_Component
(Lhs
)
1041 Possible_Bit_Aligned_Component
(Rhs
)
1045 -- If neither condition met, then nothing special to do, the back end
1046 -- can handle assignment of the entire component as a single entity.
1052 -- At this stage we know that we must do a component wise assignment
1055 Loc
: constant Source_Ptr
:= Sloc
(N
);
1056 R_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Rhs
));
1057 L_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Lhs
));
1058 Decl
: constant Node_Id
:= Declaration_Node
(R_Typ
);
1062 function Find_Component
1064 Comp
: Entity_Id
) return Entity_Id
;
1065 -- Find the component with the given name in the underlying record
1066 -- declaration for Typ. We need to use the actual entity because
1067 -- the type may be private and resolution by identifier alone would
1070 function Make_Component_List_Assign
(CL
: Node_Id
) return List_Id
;
1071 -- Returns a sequence of statements to assign the components that
1072 -- are referenced in the given component list.
1074 function Make_Field_Assign
(C
: Entity_Id
) return Node_Id
;
1075 -- Given C, the entity for a discriminant or component, build
1076 -- an assignment for the corresponding field values.
1078 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
;
1079 -- Given CI, a component items list, construct series of statements
1080 -- for fieldwise assignment of the corresponding components.
1082 --------------------
1083 -- Find_Component --
1084 --------------------
1086 function Find_Component
1088 Comp
: Entity_Id
) return Entity_Id
1090 Utyp
: constant Entity_Id
:= Underlying_Type
(Typ
);
1094 C
:= First_Entity
(Utyp
);
1096 while Present
(C
) loop
1097 if Chars
(C
) = Chars
(Comp
) then
1103 raise Program_Error
;
1106 --------------------------------
1107 -- Make_Component_List_Assign --
1108 --------------------------------
1110 function Make_Component_List_Assign
(CL
: Node_Id
) return List_Id
is
1111 CI
: constant List_Id
:= Component_Items
(CL
);
1112 VP
: constant Node_Id
:= Variant_Part
(CL
);
1121 Result
:= Make_Field_Assigns
(CI
);
1123 if Present
(VP
) then
1125 V
:= First_Non_Pragma
(Variants
(VP
));
1127 while Present
(V
) loop
1130 DC
:= First
(Discrete_Choices
(V
));
1131 while Present
(DC
) loop
1132 Append_To
(DCH
, New_Copy_Tree
(DC
));
1137 Make_Case_Statement_Alternative
(Loc
,
1138 Discrete_Choices
=> DCH
,
1140 Make_Component_List_Assign
(Component_List
(V
))));
1141 Next_Non_Pragma
(V
);
1145 Make_Case_Statement
(Loc
,
1147 Make_Selected_Component
(Loc
,
1148 Prefix
=> Duplicate_Subexpr
(Rhs
),
1150 Make_Identifier
(Loc
, Chars
(Name
(VP
)))),
1151 Alternatives
=> Alts
));
1156 end Make_Component_List_Assign
;
1158 -----------------------
1159 -- Make_Field_Assign --
1160 -----------------------
1162 function Make_Field_Assign
(C
: Entity_Id
) return Node_Id
is
1167 Make_Assignment_Statement
(Loc
,
1169 Make_Selected_Component
(Loc
,
1170 Prefix
=> Duplicate_Subexpr
(Lhs
),
1172 New_Occurrence_Of
(Find_Component
(L_Typ
, C
), Loc
)),
1174 Make_Selected_Component
(Loc
,
1175 Prefix
=> Duplicate_Subexpr
(Rhs
),
1176 Selector_Name
=> New_Occurrence_Of
(C
, Loc
)));
1178 -- Set Assignment_OK, so discriminants can be assigned
1180 Set_Assignment_OK
(Name
(A
), True);
1182 end Make_Field_Assign
;
1184 ------------------------
1185 -- Make_Field_Assigns --
1186 ------------------------
1188 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
is
1196 while Present
(Item
) loop
1197 if Nkind
(Item
) = N_Component_Declaration
then
1199 (Result
, Make_Field_Assign
(Defining_Identifier
(Item
)));
1206 end Make_Field_Assigns
;
1208 -- Start of processing for Expand_Assign_Record
1211 -- Note that we use the base types for this processing. This results
1212 -- in some extra work in the constrained case, but the change of
1213 -- representation case is so unusual that it is not worth the effort.
1215 -- First copy the discriminants. This is done unconditionally. It
1216 -- is required in the unconstrained left side case, and also in the
1217 -- case where this assignment was constructed during the expansion
1218 -- of a type conversion (since initialization of discriminants is
1219 -- suppressed in this case). It is unnecessary but harmless in
1222 if Has_Discriminants
(L_Typ
) then
1223 F
:= First_Discriminant
(R_Typ
);
1224 while Present
(F
) loop
1225 Insert_Action
(N
, Make_Field_Assign
(F
));
1226 Next_Discriminant
(F
);
1230 -- We know the underlying type is a record, but its current view
1231 -- may be private. We must retrieve the usable record declaration.
1233 if Nkind
(Decl
) = N_Private_Type_Declaration
1234 and then Present
(Full_View
(R_Typ
))
1236 RDef
:= Type_Definition
(Declaration_Node
(Full_View
(R_Typ
)));
1238 RDef
:= Type_Definition
(Decl
);
1241 if Nkind
(RDef
) = N_Record_Definition
1242 and then Present
(Component_List
(RDef
))
1245 (N
, Make_Component_List_Assign
(Component_List
(RDef
)));
1247 Rewrite
(N
, Make_Null_Statement
(Loc
));
1251 end Expand_Assign_Record
;
1253 -----------------------------------
1254 -- Expand_N_Assignment_Statement --
1255 -----------------------------------
1257 -- For array types, deal with slice assignments and setting the flags
1258 -- to indicate if it can be statically determined which direction the
1259 -- move should go in. Also deal with generating range/length checks.
1261 procedure Expand_N_Assignment_Statement
(N
: Node_Id
) is
1262 Loc
: constant Source_Ptr
:= Sloc
(N
);
1263 Lhs
: constant Node_Id
:= Name
(N
);
1264 Rhs
: constant Node_Id
:= Expression
(N
);
1265 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Lhs
));
1269 -- First deal with generation of range check if required. For now
1270 -- we do this only for discrete types.
1272 if Do_Range_Check
(Rhs
)
1273 and then Is_Discrete_Type
(Typ
)
1275 Set_Do_Range_Check
(Rhs
, False);
1276 Generate_Range_Check
(Rhs
, Typ
, CE_Range_Check_Failed
);
1279 -- Check for a special case where a high level transformation is
1280 -- required. If we have either of:
1285 -- where P is a reference to a bit packed array, then we have to unwind
1286 -- the assignment. The exact meaning of being a reference to a bit
1287 -- packed array is as follows:
1289 -- An indexed component whose prefix is a bit packed array is a
1290 -- reference to a bit packed array.
1292 -- An indexed component or selected component whose prefix is a
1293 -- reference to a bit packed array is itself a reference ot a
1294 -- bit packed array.
1296 -- The required transformation is
1298 -- Tnn : prefix_type := P;
1299 -- Tnn.field := rhs;
1304 -- Tnn : prefix_type := P;
1305 -- Tnn (subscr) := rhs;
1308 -- Since P is going to be evaluated more than once, any subscripts
1309 -- in P must have their evaluation forced.
1311 if (Nkind
(Lhs
) = N_Indexed_Component
1313 Nkind
(Lhs
) = N_Selected_Component
)
1314 and then Is_Ref_To_Bit_Packed_Array
(Prefix
(Lhs
))
1317 BPAR_Expr
: constant Node_Id
:= Relocate_Node
(Prefix
(Lhs
));
1318 BPAR_Typ
: constant Entity_Id
:= Etype
(BPAR_Expr
);
1319 Tnn
: constant Entity_Id
:=
1320 Make_Defining_Identifier
(Loc
,
1321 Chars
=> New_Internal_Name
('T'));
1324 -- Insert the post assignment first, because we want to copy
1325 -- the BPAR_Expr tree before it gets analyzed in the context
1326 -- of the pre assignment. Note that we do not analyze the
1327 -- post assignment yet (we cannot till we have completed the
1328 -- analysis of the pre assignment). As usual, the analysis
1329 -- of this post assignment will happen on its own when we
1330 -- "run into" it after finishing the current assignment.
1333 Make_Assignment_Statement
(Loc
,
1334 Name
=> New_Copy_Tree
(BPAR_Expr
),
1335 Expression
=> New_Occurrence_Of
(Tnn
, Loc
)));
1337 -- At this stage BPAR_Expr is a reference to a bit packed
1338 -- array where the reference was not expanded in the original
1339 -- tree, since it was on the left side of an assignment. But
1340 -- in the pre-assignment statement (the object definition),
1341 -- BPAR_Expr will end up on the right hand side, and must be
1342 -- reexpanded. To achieve this, we reset the analyzed flag
1343 -- of all selected and indexed components down to the actual
1344 -- indexed component for the packed array.
1348 Set_Analyzed
(Exp
, False);
1350 if Nkind
(Exp
) = N_Selected_Component
1352 Nkind
(Exp
) = N_Indexed_Component
1354 Exp
:= Prefix
(Exp
);
1360 -- Now we can insert and analyze the pre-assignment.
1362 -- If the right-hand side requires a transient scope, it has
1363 -- already been placed on the stack. However, the declaration is
1364 -- inserted in the tree outside of this scope, and must reflect
1365 -- the proper scope for its variable. This awkward bit is forced
1366 -- by the stricter scope discipline imposed by GCC 2.97.
1369 Uses_Transient_Scope
: constant Boolean :=
1370 Scope_Is_Transient
and then N
= Node_To_Be_Wrapped
;
1373 if Uses_Transient_Scope
then
1374 New_Scope
(Scope
(Current_Scope
));
1377 Insert_Before_And_Analyze
(N
,
1378 Make_Object_Declaration
(Loc
,
1379 Defining_Identifier
=> Tnn
,
1380 Object_Definition
=> New_Occurrence_Of
(BPAR_Typ
, Loc
),
1381 Expression
=> BPAR_Expr
));
1383 if Uses_Transient_Scope
then
1388 -- Now fix up the original assignment and continue processing
1390 Rewrite
(Prefix
(Lhs
),
1391 New_Occurrence_Of
(Tnn
, Loc
));
1393 -- We do not need to reanalyze that assignment, and we do not need
1394 -- to worry about references to the temporary, but we do need to
1395 -- make sure that the temporary is not marked as a true constant
1396 -- since we now have a generate assignment to it!
1398 Set_Is_True_Constant
(Tnn
, False);
1402 -- When we have the appropriate type of aggregate in the
1403 -- expression (it has been determined during analysis of the
1404 -- aggregate by setting the delay flag), let's perform in place
1405 -- assignment and thus avoid creating a temporay.
1407 if Is_Delayed_Aggregate
(Rhs
) then
1408 Convert_Aggr_In_Assignment
(N
);
1409 Rewrite
(N
, Make_Null_Statement
(Loc
));
1414 -- Apply discriminant check if required. If Lhs is an access type
1415 -- to a designated type with discriminants, we must always check.
1417 if Has_Discriminants
(Etype
(Lhs
)) then
1419 -- Skip discriminant check if change of representation. Will be
1420 -- done when the change of representation is expanded out.
1422 if not Change_Of_Representation
(N
) then
1423 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
), Lhs
);
1426 -- If the type is private without discriminants, and the full type
1427 -- has discriminants (necessarily with defaults) a check may still be
1428 -- necessary if the Lhs is aliased. The private determinants must be
1429 -- visible to build the discriminant constraints.
1431 -- Only an explicit dereference that comes from source indicates
1432 -- aliasing. Access to formals of protected operations and entries
1433 -- create dereferences but are not semantic aliasings.
1435 elsif Is_Private_Type
(Etype
(Lhs
))
1436 and then Has_Discriminants
(Typ
)
1437 and then Nkind
(Lhs
) = N_Explicit_Dereference
1438 and then Comes_From_Source
(Lhs
)
1441 Lt
: constant Entity_Id
:= Etype
(Lhs
);
1443 Set_Etype
(Lhs
, Typ
);
1444 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
1445 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
1446 Set_Etype
(Lhs
, Lt
);
1449 -- If the Lhs has a private type with unknown discriminants, it
1450 -- may have a full view with discriminants, but those are nameable
1451 -- only in the underlying type, so convert the Rhs to it before
1452 -- potential checking.
1454 elsif Has_Unknown_Discriminants
(Base_Type
(Etype
(Lhs
)))
1455 and then Has_Discriminants
(Typ
)
1457 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
1458 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
1460 -- In the access type case, we need the same discriminant check,
1461 -- and also range checks if we have an access to constrained array.
1463 elsif Is_Access_Type
(Etype
(Lhs
))
1464 and then Is_Constrained
(Designated_Type
(Etype
(Lhs
)))
1466 if Has_Discriminants
(Designated_Type
(Etype
(Lhs
))) then
1468 -- Skip discriminant check if change of representation. Will be
1469 -- done when the change of representation is expanded out.
1471 if not Change_Of_Representation
(N
) then
1472 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
));
1475 elsif Is_Array_Type
(Designated_Type
(Etype
(Lhs
))) then
1476 Apply_Range_Check
(Rhs
, Etype
(Lhs
));
1478 if Is_Constrained
(Etype
(Lhs
)) then
1479 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
1482 if Nkind
(Rhs
) = N_Allocator
then
1484 Target_Typ
: constant Entity_Id
:= Etype
(Expression
(Rhs
));
1485 C_Es
: Check_Result
;
1492 Etype
(Designated_Type
(Etype
(Lhs
))));
1504 -- Apply range check for access type case
1506 elsif Is_Access_Type
(Etype
(Lhs
))
1507 and then Nkind
(Rhs
) = N_Allocator
1508 and then Nkind
(Expression
(Rhs
)) = N_Qualified_Expression
1510 Analyze_And_Resolve
(Expression
(Rhs
));
1512 (Expression
(Rhs
), Designated_Type
(Etype
(Lhs
)));
1515 -- If we are assigning an access type and the left side is an
1516 -- entity, then make sure that Is_Known_Non_Null properly
1517 -- reflects the state of the entity after the assignment
1519 if Is_Access_Type
(Typ
)
1520 and then Is_Entity_Name
(Lhs
)
1521 and then Known_Non_Null
(Rhs
)
1522 and then Safe_To_Capture_Value
(N
, Entity
(Lhs
))
1524 Set_Is_Known_Non_Null
(Entity
(Lhs
), Known_Non_Null
(Rhs
));
1527 -- Case of assignment to a bit packed array element
1529 if Nkind
(Lhs
) = N_Indexed_Component
1530 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Lhs
)))
1532 Expand_Bit_Packed_Element_Set
(N
);
1535 -- Case of tagged type assignment
1537 elsif Is_Tagged_Type
(Typ
)
1538 or else (Controlled_Type
(Typ
) and then not Is_Array_Type
(Typ
))
1540 Tagged_Case
: declare
1541 L
: List_Id
:= No_List
;
1542 Expand_Ctrl_Actions
: constant Boolean := not No_Ctrl_Actions
(N
);
1545 -- In the controlled case, we need to make sure that function
1546 -- calls are evaluated before finalizing the target. In all
1547 -- cases, it makes the expansion easier if the side-effects
1548 -- are removed first.
1550 Remove_Side_Effects
(Lhs
);
1551 Remove_Side_Effects
(Rhs
);
1553 -- Avoid recursion in the mechanism
1557 -- If dispatching assignment, we need to dispatch to _assign
1559 if Is_Class_Wide_Type
(Typ
)
1561 -- If the type is tagged, we may as well use the predefined
1562 -- primitive assignment. This avoids inlining a lot of code
1563 -- and in the class-wide case, the assignment is replaced by
1564 -- a dispatch call to _assign. Note that this cannot be done
1565 -- when discriminant checks are locally suppressed (as in
1566 -- extension aggregate expansions) because otherwise the
1567 -- discriminant check will be performed within the _assign
1570 or else (Is_Tagged_Type
(Typ
)
1571 and then Chars
(Current_Scope
) /= Name_uAssign
1572 and then Expand_Ctrl_Actions
1573 and then not Discriminant_Checks_Suppressed
(Empty
))
1575 -- Fetch the primitive op _assign and proper type to call
1576 -- it. Because of possible conflits between private and
1577 -- full view the proper type is fetched directly from the
1578 -- operation profile.
1581 Op
: constant Entity_Id
:=
1582 Find_Prim_Op
(Typ
, Name_uAssign
);
1583 F_Typ
: Entity_Id
:= Etype
(First_Formal
(Op
));
1586 -- If the assignment is dispatching, make sure to use the
1587 -- ??? where is rest of this comment ???
1589 if Is_Class_Wide_Type
(Typ
) then
1590 F_Typ
:= Class_Wide_Type
(F_Typ
);
1594 Make_Procedure_Call_Statement
(Loc
,
1595 Name
=> New_Reference_To
(Op
, Loc
),
1596 Parameter_Associations
=> New_List
(
1597 Unchecked_Convert_To
(F_Typ
, Duplicate_Subexpr
(Lhs
)),
1598 Unchecked_Convert_To
(F_Typ
,
1599 Duplicate_Subexpr
(Rhs
)))));
1603 L
:= Make_Tag_Ctrl_Assignment
(N
);
1605 -- We can't afford to have destructive Finalization Actions
1606 -- in the Self assignment case, so if the target and the
1607 -- source are not obviously different, code is generated to
1608 -- avoid the self assignment case
1610 -- if lhs'address /= rhs'address then
1611 -- <code for controlled and/or tagged assignment>
1614 if not Statically_Different
(Lhs
, Rhs
)
1615 and then Expand_Ctrl_Actions
1618 Make_Implicit_If_Statement
(N
,
1622 Make_Attribute_Reference
(Loc
,
1623 Prefix
=> Duplicate_Subexpr
(Lhs
),
1624 Attribute_Name
=> Name_Address
),
1627 Make_Attribute_Reference
(Loc
,
1628 Prefix
=> Duplicate_Subexpr
(Rhs
),
1629 Attribute_Name
=> Name_Address
)),
1631 Then_Statements
=> L
));
1634 -- We need to set up an exception handler for implementing
1635 -- 7.6.1 (18). The remaining adjustments are tackled by the
1636 -- implementation of adjust for record_controllers (see
1639 -- This is skipped if we have no finalization
1641 if Expand_Ctrl_Actions
1642 and then not Restrictions
(No_Finalization
)
1645 Make_Block_Statement
(Loc
,
1646 Handled_Statement_Sequence
=>
1647 Make_Handled_Sequence_Of_Statements
(Loc
,
1649 Exception_Handlers
=> New_List
(
1650 Make_Exception_Handler
(Loc
,
1651 Exception_Choices
=>
1652 New_List
(Make_Others_Choice
(Loc
)),
1653 Statements
=> New_List
(
1654 Make_Raise_Program_Error
(Loc
,
1656 PE_Finalize_Raised_Exception
)
1662 Make_Block_Statement
(Loc
,
1663 Handled_Statement_Sequence
=>
1664 Make_Handled_Sequence_Of_Statements
(Loc
, Statements
=> L
)));
1666 -- If no restrictions on aborts, protect the whole assignement
1667 -- for controlled objects as per 9.8(11)
1669 if Controlled_Type
(Typ
)
1670 and then Expand_Ctrl_Actions
1671 and then Abort_Allowed
1674 Blk
: constant Entity_Id
:=
1675 New_Internal_Entity
(
1676 E_Block
, Current_Scope
, Sloc
(N
), 'B');
1679 Set_Scope
(Blk
, Current_Scope
);
1680 Set_Etype
(Blk
, Standard_Void_Type
);
1681 Set_Identifier
(N
, New_Occurrence_Of
(Blk
, Sloc
(N
)));
1683 Prepend_To
(L
, Build_Runtime_Call
(Loc
, RE_Abort_Defer
));
1684 Set_At_End_Proc
(Handled_Statement_Sequence
(N
),
1685 New_Occurrence_Of
(RTE
(RE_Abort_Undefer_Direct
), Loc
));
1686 Expand_At_End_Handler
1687 (Handled_Statement_Sequence
(N
), Blk
);
1697 elsif Is_Array_Type
(Typ
) then
1699 Actual_Rhs
: Node_Id
:= Rhs
;
1702 while Nkind
(Actual_Rhs
) = N_Type_Conversion
1704 Nkind
(Actual_Rhs
) = N_Qualified_Expression
1706 Actual_Rhs
:= Expression
(Actual_Rhs
);
1709 Expand_Assign_Array
(N
, Actual_Rhs
);
1715 elsif Is_Record_Type
(Typ
) then
1716 Expand_Assign_Record
(N
);
1719 -- Scalar types. This is where we perform the processing related
1720 -- to the requirements of (RM 13.9.1(9-11)) concerning the handling
1721 -- of invalid scalar values.
1723 elsif Is_Scalar_Type
(Typ
) then
1725 -- Case where right side is known valid
1727 if Expr_Known_Valid
(Rhs
) then
1729 -- Here the right side is valid, so it is fine. The case to
1730 -- deal with is when the left side is a local variable reference
1731 -- whose value is not currently known to be valid. If this is
1732 -- the case, and the assignment appears in an unconditional
1733 -- context, then we can mark the left side as now being valid.
1735 if Is_Local_Variable_Reference
(Lhs
)
1736 and then not Is_Known_Valid
(Entity
(Lhs
))
1737 and then In_Unconditional_Context
(N
)
1739 Set_Is_Known_Valid
(Entity
(Lhs
), True);
1742 -- Case where right side may be invalid in the sense of the RM
1743 -- reference above. The RM does not require that we check for
1744 -- the validity on an assignment, but it does require that the
1745 -- assignment of an invalid value not cause erroneous behavior.
1747 -- The general approach in GNAT is to use the Is_Known_Valid flag
1748 -- to avoid the need for validity checking on assignments. However
1749 -- in some cases, we have to do validity checking in order to make
1750 -- sure that the setting of this flag is correct.
1753 -- Validate right side if we are validating copies
1755 if Validity_Checks_On
1756 and then Validity_Check_Copies
1760 -- We can propagate this to the left side where appropriate
1762 if Is_Local_Variable_Reference
(Lhs
)
1763 and then not Is_Known_Valid
(Entity
(Lhs
))
1764 and then In_Unconditional_Context
(N
)
1766 Set_Is_Known_Valid
(Entity
(Lhs
), True);
1769 -- Otherwise check to see what should be done
1771 -- If left side is a local variable, then we just set its
1772 -- flag to indicate that its value may no longer be valid,
1773 -- since we are copying a potentially invalid value.
1775 elsif Is_Local_Variable_Reference
(Lhs
) then
1776 Set_Is_Known_Valid
(Entity
(Lhs
), False);
1778 -- Check for case of a nonlocal variable on the left side
1779 -- which is currently known to be valid. In this case, we
1780 -- simply ensure that the right side is valid. We only play
1781 -- the game of copying validity status for local variables,
1782 -- since we are doing this statically, not by tracing the
1785 elsif Is_Entity_Name
(Lhs
)
1786 and then Is_Known_Valid
(Entity
(Lhs
))
1788 -- Note that the Ensure_Valid call is ignored if the
1789 -- Validity_Checking mode is set to none so we do not
1790 -- need to worry about that case here.
1794 -- In all other cases, we can safely copy an invalid value
1795 -- without worrying about the status of the left side. Since
1796 -- it is not a variable reference it will not be considered
1797 -- as being known to be valid in any case.
1805 -- Defend against invalid subscripts on left side if we are in
1806 -- standard validity checking mode. No need to do this if we
1807 -- are checking all subscripts.
1809 if Validity_Checks_On
1810 and then Validity_Check_Default
1811 and then not Validity_Check_Subscripts
1813 Check_Valid_Lvalue_Subscripts
(Lhs
);
1817 when RE_Not_Available
=>
1819 end Expand_N_Assignment_Statement
;
1821 ------------------------------
1822 -- Expand_N_Block_Statement --
1823 ------------------------------
1825 -- Encode entity names defined in block statement
1827 procedure Expand_N_Block_Statement
(N
: Node_Id
) is
1829 Qualify_Entity_Names
(N
);
1830 end Expand_N_Block_Statement
;
1832 -----------------------------
1833 -- Expand_N_Case_Statement --
1834 -----------------------------
1836 procedure Expand_N_Case_Statement
(N
: Node_Id
) is
1837 Loc
: constant Source_Ptr
:= Sloc
(N
);
1838 Expr
: constant Node_Id
:= Expression
(N
);
1846 -- Check for the situation where we know at compile time which
1847 -- branch will be taken
1849 if Compile_Time_Known_Value
(Expr
) then
1850 Alt
:= Find_Static_Alternative
(N
);
1852 -- Move the statements from this alternative after the case
1853 -- statement. They are already analyzed, so will be skipped
1856 Insert_List_After
(N
, Statements
(Alt
));
1858 -- That leaves the case statement as a shell. The alternative
1859 -- that will be executed is reset to a null list. So now we can
1860 -- kill the entire case statement.
1862 Kill_Dead_Code
(Expression
(N
));
1863 Kill_Dead_Code
(Alternatives
(N
));
1864 Rewrite
(N
, Make_Null_Statement
(Loc
));
1868 -- Here if the choice is not determined at compile time
1871 Last_Alt
: constant Node_Id
:= Last
(Alternatives
(N
));
1873 Others_Present
: Boolean;
1874 Others_Node
: Node_Id
;
1876 Then_Stms
: List_Id
;
1877 Else_Stms
: List_Id
;
1880 if Nkind
(First
(Discrete_Choices
(Last_Alt
))) = N_Others_Choice
then
1881 Others_Present
:= True;
1882 Others_Node
:= Last_Alt
;
1884 Others_Present
:= False;
1887 -- First step is to worry about possible invalid argument. The RM
1888 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
1889 -- outside the base range), then Constraint_Error must be raised.
1891 -- Case of validity check required (validity checks are on, the
1892 -- expression is not known to be valid, and the case statement
1893 -- comes from source -- no need to validity check internally
1894 -- generated case statements).
1896 if Validity_Check_Default
then
1897 Ensure_Valid
(Expr
);
1900 -- If there is only a single alternative, just replace it with
1901 -- the sequence of statements since obviously that is what is
1902 -- going to be executed in all cases.
1904 Len
:= List_Length
(Alternatives
(N
));
1907 -- We still need to evaluate the expression if it has any
1910 Remove_Side_Effects
(Expression
(N
));
1912 Insert_List_After
(N
, Statements
(First
(Alternatives
(N
))));
1914 -- That leaves the case statement as a shell. The alternative
1915 -- that will be executed is reset to a null list. So now we can
1916 -- kill the entire case statement.
1918 Kill_Dead_Code
(Expression
(N
));
1919 Rewrite
(N
, Make_Null_Statement
(Loc
));
1923 -- An optimization. If there are only two alternatives, and only
1924 -- a single choice, then rewrite the whole case statement as an
1925 -- if statement, since this can result in susbequent optimizations.
1926 -- This helps not only with case statements in the source of a
1927 -- simple form, but also with generated code (discriminant check
1928 -- functions in particular)
1931 Chlist
:= Discrete_Choices
(First
(Alternatives
(N
)));
1933 if List_Length
(Chlist
) = 1 then
1934 Choice
:= First
(Chlist
);
1936 Then_Stms
:= Statements
(First
(Alternatives
(N
)));
1937 Else_Stms
:= Statements
(Last
(Alternatives
(N
)));
1939 -- For TRUE, generate "expression", not expression = true
1941 if Nkind
(Choice
) = N_Identifier
1942 and then Entity
(Choice
) = Standard_True
1944 Cond
:= Expression
(N
);
1946 -- For FALSE, generate "expression" and switch then/else
1948 elsif Nkind
(Choice
) = N_Identifier
1949 and then Entity
(Choice
) = Standard_False
1951 Cond
:= Expression
(N
);
1952 Else_Stms
:= Statements
(First
(Alternatives
(N
)));
1953 Then_Stms
:= Statements
(Last
(Alternatives
(N
)));
1955 -- For a range, generate "expression in range"
1957 elsif Nkind
(Choice
) = N_Range
1958 or else (Nkind
(Choice
) = N_Attribute_Reference
1959 and then Attribute_Name
(Choice
) = Name_Range
)
1960 or else (Is_Entity_Name
(Choice
)
1961 and then Is_Type
(Entity
(Choice
)))
1962 or else Nkind
(Choice
) = N_Subtype_Indication
1966 Left_Opnd
=> Expression
(N
),
1967 Right_Opnd
=> Relocate_Node
(Choice
));
1969 -- For any other subexpression "expression = value"
1974 Left_Opnd
=> Expression
(N
),
1975 Right_Opnd
=> Relocate_Node
(Choice
));
1978 -- Now rewrite the case as an IF
1981 Make_If_Statement
(Loc
,
1983 Then_Statements
=> Then_Stms
,
1984 Else_Statements
=> Else_Stms
));
1990 -- If the last alternative is not an Others choice, replace it
1991 -- with an N_Others_Choice. Note that we do not bother to call
1992 -- Analyze on the modified case statement, since it's only effect
1993 -- would be to compute the contents of the Others_Discrete_Choices
1994 -- which is not needed by the back end anyway.
1996 -- The reason we do this is that the back end always needs some
1997 -- default for a switch, so if we have not supplied one in the
1998 -- processing above for validity checking, then we need to
2001 if not Others_Present
then
2002 Others_Node
:= Make_Others_Choice
(Sloc
(Last_Alt
));
2003 Set_Others_Discrete_Choices
2004 (Others_Node
, Discrete_Choices
(Last_Alt
));
2005 Set_Discrete_Choices
(Last_Alt
, New_List
(Others_Node
));
2008 end Expand_N_Case_Statement
;
2010 -----------------------------
2011 -- Expand_N_Exit_Statement --
2012 -----------------------------
2014 -- The only processing required is to deal with a possible C/Fortran
2015 -- boolean value used as the condition for the exit statement.
2017 procedure Expand_N_Exit_Statement
(N
: Node_Id
) is
2019 Adjust_Condition
(Condition
(N
));
2020 end Expand_N_Exit_Statement
;
2022 -----------------------------
2023 -- Expand_N_Goto_Statement --
2024 -----------------------------
2026 -- Add poll before goto if polling active
2028 procedure Expand_N_Goto_Statement
(N
: Node_Id
) is
2030 Generate_Poll_Call
(N
);
2031 end Expand_N_Goto_Statement
;
2033 ---------------------------
2034 -- Expand_N_If_Statement --
2035 ---------------------------
2037 -- First we deal with the case of C and Fortran convention boolean
2038 -- values, with zero/non-zero semantics.
2040 -- Second, we deal with the obvious rewriting for the cases where the
2041 -- condition of the IF is known at compile time to be True or False.
2043 -- Third, we remove elsif parts which have non-empty Condition_Actions
2044 -- and rewrite as independent if statements. For example:
2055 -- <<condition actions of y>>
2061 -- This rewriting is needed if at least one elsif part has a non-empty
2062 -- Condition_Actions list. We also do the same processing if there is
2063 -- a constant condition in an elsif part (in conjunction with the first
2064 -- processing step mentioned above, for the recursive call made to deal
2065 -- with the created inner if, this deals with properly optimizing the
2066 -- cases of constant elsif conditions).
2068 procedure Expand_N_If_Statement
(N
: Node_Id
) is
2069 Loc
: constant Source_Ptr
:= Sloc
(N
);
2075 Adjust_Condition
(Condition
(N
));
2077 -- The following loop deals with constant conditions for the IF. We
2078 -- need a loop because as we eliminate False conditions, we grab the
2079 -- first elsif condition and use it as the primary condition.
2081 while Compile_Time_Known_Value
(Condition
(N
)) loop
2083 -- If condition is True, we can simply rewrite the if statement
2084 -- now by replacing it by the series of then statements.
2086 if Is_True
(Expr_Value
(Condition
(N
))) then
2088 -- All the else parts can be killed
2090 Kill_Dead_Code
(Elsif_Parts
(N
));
2091 Kill_Dead_Code
(Else_Statements
(N
));
2093 Hed
:= Remove_Head
(Then_Statements
(N
));
2094 Insert_List_After
(N
, Then_Statements
(N
));
2098 -- If condition is False, then we can delete the condition and
2099 -- the Then statements
2102 -- We do not delete the condition if constant condition
2103 -- warnings are enabled, since otherwise we end up deleting
2104 -- the desired warning. Of course the backend will get rid
2105 -- of this True/False test anyway, so nothing is lost here.
2107 if not Constant_Condition_Warnings
then
2108 Kill_Dead_Code
(Condition
(N
));
2111 Kill_Dead_Code
(Then_Statements
(N
));
2113 -- If there are no elsif statements, then we simply replace
2114 -- the entire if statement by the sequence of else statements.
2116 if No
(Elsif_Parts
(N
)) then
2118 if No
(Else_Statements
(N
))
2119 or else Is_Empty_List
(Else_Statements
(N
))
2122 Make_Null_Statement
(Sloc
(N
)));
2125 Hed
:= Remove_Head
(Else_Statements
(N
));
2126 Insert_List_After
(N
, Else_Statements
(N
));
2132 -- If there are elsif statements, the first of them becomes
2133 -- the if/then section of the rebuilt if statement This is
2134 -- the case where we loop to reprocess this copied condition.
2137 Hed
:= Remove_Head
(Elsif_Parts
(N
));
2138 Insert_Actions
(N
, Condition_Actions
(Hed
));
2139 Set_Condition
(N
, Condition
(Hed
));
2140 Set_Then_Statements
(N
, Then_Statements
(Hed
));
2142 if Is_Empty_List
(Elsif_Parts
(N
)) then
2143 Set_Elsif_Parts
(N
, No_List
);
2149 -- Loop through elsif parts, dealing with constant conditions and
2150 -- possible expression actions that are present.
2152 if Present
(Elsif_Parts
(N
)) then
2153 E
:= First
(Elsif_Parts
(N
));
2154 while Present
(E
) loop
2155 Adjust_Condition
(Condition
(E
));
2157 -- If there are condition actions, then we rewrite the if
2158 -- statement as indicated above. We also do the same rewrite
2159 -- if the condition is True or False. The further processing
2160 -- of this constant condition is then done by the recursive
2161 -- call to expand the newly created if statement
2163 if Present
(Condition_Actions
(E
))
2164 or else Compile_Time_Known_Value
(Condition
(E
))
2166 -- Note this is not an implicit if statement, since it is
2167 -- part of an explicit if statement in the source (or of an
2168 -- implicit if statement that has already been tested).
2171 Make_If_Statement
(Sloc
(E
),
2172 Condition
=> Condition
(E
),
2173 Then_Statements
=> Then_Statements
(E
),
2174 Elsif_Parts
=> No_List
,
2175 Else_Statements
=> Else_Statements
(N
));
2177 -- Elsif parts for new if come from remaining elsif's of parent
2179 while Present
(Next
(E
)) loop
2180 if No
(Elsif_Parts
(New_If
)) then
2181 Set_Elsif_Parts
(New_If
, New_List
);
2184 Append
(Remove_Next
(E
), Elsif_Parts
(New_If
));
2187 Set_Else_Statements
(N
, New_List
(New_If
));
2189 if Present
(Condition_Actions
(E
)) then
2190 Insert_List_Before
(New_If
, Condition_Actions
(E
));
2195 if Is_Empty_List
(Elsif_Parts
(N
)) then
2196 Set_Elsif_Parts
(N
, No_List
);
2202 -- No special processing for that elsif part, move to next
2210 -- Some more optimizations applicable if we still have an IF statement
2212 if Nkind
(N
) /= N_If_Statement
then
2216 -- Another optimization, special cases that can be simplified
2218 -- if expression then
2224 -- can be changed to:
2226 -- return expression;
2230 -- if expression then
2236 -- can be changed to:
2238 -- return not (expression);
2240 if Nkind
(N
) = N_If_Statement
2241 and then No
(Elsif_Parts
(N
))
2242 and then Present
(Else_Statements
(N
))
2243 and then List_Length
(Then_Statements
(N
)) = 1
2244 and then List_Length
(Else_Statements
(N
)) = 1
2247 Then_Stm
: Node_Id
:= First
(Then_Statements
(N
));
2248 Else_Stm
: Node_Id
:= First
(Else_Statements
(N
));
2251 if Nkind
(Then_Stm
) = N_Return_Statement
2253 Nkind
(Else_Stm
) = N_Return_Statement
2256 Then_Expr
: constant Node_Id
:= Expression
(Then_Stm
);
2257 Else_Expr
: constant Node_Id
:= Expression
(Else_Stm
);
2260 if Nkind
(Then_Expr
) = N_Identifier
2262 Nkind
(Else_Expr
) = N_Identifier
2264 if Entity
(Then_Expr
) = Standard_True
2265 and then Entity
(Else_Expr
) = Standard_False
2268 Make_Return_Statement
(Loc
,
2269 Expression
=> Relocate_Node
(Condition
(N
))));
2273 elsif Entity
(Then_Expr
) = Standard_False
2274 and then Entity
(Else_Expr
) = Standard_True
2277 Make_Return_Statement
(Loc
,
2280 Right_Opnd
=> Relocate_Node
(Condition
(N
)))));
2289 end Expand_N_If_Statement
;
2291 -----------------------------
2292 -- Expand_N_Loop_Statement --
2293 -----------------------------
2295 -- 1. Deal with while condition for C/Fortran boolean
2296 -- 2. Deal with loops with a non-standard enumeration type range
2297 -- 3. Deal with while loops where Condition_Actions is set
2298 -- 4. Insert polling call if required
2300 procedure Expand_N_Loop_Statement
(N
: Node_Id
) is
2301 Loc
: constant Source_Ptr
:= Sloc
(N
);
2302 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
2305 if Present
(Isc
) then
2306 Adjust_Condition
(Condition
(Isc
));
2309 if Is_Non_Empty_List
(Statements
(N
)) then
2310 Generate_Poll_Call
(First
(Statements
(N
)));
2317 -- Handle the case where we have a for loop with the range type being
2318 -- an enumeration type with non-standard representation. In this case
2321 -- for x in [reverse] a .. b loop
2327 -- for xP in [reverse] integer
2328 -- range etype'Pos (a) .. etype'Pos (b) loop
2330 -- x : constant etype := Pos_To_Rep (xP);
2336 if Present
(Loop_Parameter_Specification
(Isc
)) then
2338 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Isc
);
2339 Loop_Id
: constant Entity_Id
:= Defining_Identifier
(LPS
);
2340 Ltype
: constant Entity_Id
:= Etype
(Loop_Id
);
2341 Btype
: constant Entity_Id
:= Base_Type
(Ltype
);
2346 if not Is_Enumeration_Type
(Btype
)
2347 or else No
(Enum_Pos_To_Rep
(Btype
))
2353 Make_Defining_Identifier
(Loc
,
2354 Chars
=> New_External_Name
(Chars
(Loop_Id
), 'P'));
2356 -- If the type has a contiguous representation, successive
2357 -- values can be generated as offsets from the first literal.
2359 if Has_Contiguous_Rep
(Btype
) then
2361 Unchecked_Convert_To
(Btype
,
2364 Make_Integer_Literal
(Loc
,
2365 Enumeration_Rep
(First_Literal
(Btype
))),
2366 Right_Opnd
=> New_Reference_To
(New_Id
, Loc
)));
2368 -- Use the constructed array Enum_Pos_To_Rep.
2371 Make_Indexed_Component
(Loc
,
2372 Prefix
=> New_Reference_To
(Enum_Pos_To_Rep
(Btype
), Loc
),
2373 Expressions
=> New_List
(New_Reference_To
(New_Id
, Loc
)));
2377 Make_Loop_Statement
(Loc
,
2378 Identifier
=> Identifier
(N
),
2381 Make_Iteration_Scheme
(Loc
,
2382 Loop_Parameter_Specification
=>
2383 Make_Loop_Parameter_Specification
(Loc
,
2384 Defining_Identifier
=> New_Id
,
2385 Reverse_Present
=> Reverse_Present
(LPS
),
2387 Discrete_Subtype_Definition
=>
2388 Make_Subtype_Indication
(Loc
,
2391 New_Reference_To
(Standard_Natural
, Loc
),
2394 Make_Range_Constraint
(Loc
,
2399 Make_Attribute_Reference
(Loc
,
2401 New_Reference_To
(Btype
, Loc
),
2403 Attribute_Name
=> Name_Pos
,
2405 Expressions
=> New_List
(
2407 (Type_Low_Bound
(Ltype
)))),
2410 Make_Attribute_Reference
(Loc
,
2412 New_Reference_To
(Btype
, Loc
),
2414 Attribute_Name
=> Name_Pos
,
2416 Expressions
=> New_List
(
2418 (Type_High_Bound
(Ltype
))))))))),
2420 Statements
=> New_List
(
2421 Make_Block_Statement
(Loc
,
2422 Declarations
=> New_List
(
2423 Make_Object_Declaration
(Loc
,
2424 Defining_Identifier
=> Loop_Id
,
2425 Constant_Present
=> True,
2426 Object_Definition
=> New_Reference_To
(Ltype
, Loc
),
2427 Expression
=> Expr
)),
2429 Handled_Statement_Sequence
=>
2430 Make_Handled_Sequence_Of_Statements
(Loc
,
2431 Statements
=> Statements
(N
)))),
2433 End_Label
=> End_Label
(N
)));
2437 -- Second case, if we have a while loop with Condition_Actions set,
2438 -- then we change it into a plain loop:
2447 -- <<condition actions>>
2453 and then Present
(Condition_Actions
(Isc
))
2460 Make_Exit_Statement
(Sloc
(Condition
(Isc
)),
2462 Make_Op_Not
(Sloc
(Condition
(Isc
)),
2463 Right_Opnd
=> Condition
(Isc
)));
2465 Prepend
(ES
, Statements
(N
));
2466 Insert_List_Before
(ES
, Condition_Actions
(Isc
));
2468 -- This is not an implicit loop, since it is generated in
2469 -- response to the loop statement being processed. If this
2470 -- is itself implicit, the restriction has already been
2471 -- checked. If not, it is an explicit loop.
2474 Make_Loop_Statement
(Sloc
(N
),
2475 Identifier
=> Identifier
(N
),
2476 Statements
=> Statements
(N
),
2477 End_Label
=> End_Label
(N
)));
2482 end Expand_N_Loop_Statement
;
2484 -------------------------------
2485 -- Expand_N_Return_Statement --
2486 -------------------------------
2488 procedure Expand_N_Return_Statement
(N
: Node_Id
) is
2489 Loc
: constant Source_Ptr
:= Sloc
(N
);
2490 Exp
: constant Node_Id
:= Expression
(N
);
2494 Scope_Id
: Entity_Id
;
2498 Goto_Stat
: Node_Id
;
2501 Return_Type
: Entity_Id
;
2502 Result_Exp
: Node_Id
;
2503 Result_Id
: Entity_Id
;
2504 Result_Obj
: Node_Id
;
2507 -- Case where returned expression is present
2509 if Present
(Exp
) then
2511 -- Always normalize C/Fortran boolean result. This is not always
2512 -- necessary, but it seems a good idea to minimize the passing
2513 -- around of non-normalized values, and in any case this handles
2514 -- the processing of barrier functions for protected types, which
2515 -- turn the condition into a return statement.
2517 Exptyp
:= Etype
(Exp
);
2519 if Is_Boolean_Type
(Exptyp
)
2520 and then Nonzero_Is_True
(Exptyp
)
2522 Adjust_Condition
(Exp
);
2523 Adjust_Result_Type
(Exp
, Exptyp
);
2526 -- Do validity check if enabled for returns
2528 if Validity_Checks_On
2529 and then Validity_Check_Returns
2535 -- Find relevant enclosing scope from which return is returning
2537 Cur_Idx
:= Scope_Stack
.Last
;
2539 Scope_Id
:= Scope_Stack
.Table
(Cur_Idx
).Entity
;
2541 if Ekind
(Scope_Id
) /= E_Block
2542 and then Ekind
(Scope_Id
) /= E_Loop
2547 Cur_Idx
:= Cur_Idx
- 1;
2548 pragma Assert
(Cur_Idx
>= 0);
2553 Kind
:= Ekind
(Scope_Id
);
2555 -- If it is a return from procedures do no extra steps.
2557 if Kind
= E_Procedure
or else Kind
= E_Generic_Procedure
then
2561 pragma Assert
(Is_Entry
(Scope_Id
));
2563 -- Look at the enclosing block to see whether the return is from
2564 -- an accept statement or an entry body.
2566 for J
in reverse 0 .. Cur_Idx
loop
2567 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
2568 exit when Is_Concurrent_Type
(Scope_Id
);
2571 -- If it is a return from accept statement it should be expanded
2572 -- as a call to RTS Complete_Rendezvous and a goto to the end of
2575 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
2576 -- Expand_N_Accept_Alternative in exp_ch9.adb)
2578 if Is_Task_Type
(Scope_Id
) then
2580 Call
:= (Make_Procedure_Call_Statement
(Loc
,
2581 Name
=> New_Reference_To
2582 (RTE
(RE_Complete_Rendezvous
), Loc
)));
2583 Insert_Before
(N
, Call
);
2584 -- why not insert actions here???
2587 Acc_Stat
:= Parent
(N
);
2588 while Nkind
(Acc_Stat
) /= N_Accept_Statement
loop
2589 Acc_Stat
:= Parent
(Acc_Stat
);
2592 Lab_Node
:= Last
(Statements
2593 (Handled_Statement_Sequence
(Acc_Stat
)));
2595 Goto_Stat
:= Make_Goto_Statement
(Loc
,
2596 Name
=> New_Occurrence_Of
2597 (Entity
(Identifier
(Lab_Node
)), Loc
));
2599 Set_Analyzed
(Goto_Stat
);
2601 Rewrite
(N
, Goto_Stat
);
2604 -- If it is a return from an entry body, put a Complete_Entry_Body
2605 -- call in front of the return.
2607 elsif Is_Protected_Type
(Scope_Id
) then
2610 Make_Procedure_Call_Statement
(Loc
,
2611 Name
=> New_Reference_To
2612 (RTE
(RE_Complete_Entry_Body
), Loc
),
2613 Parameter_Associations
=> New_List
2614 (Make_Attribute_Reference
(Loc
,
2618 (Corresponding_Body
(Parent
(Scope_Id
))),
2620 Attribute_Name
=> Name_Unchecked_Access
)));
2622 Insert_Before
(N
, Call
);
2631 Return_Type
:= Etype
(Scope_Id
);
2632 Utyp
:= Underlying_Type
(Return_Type
);
2634 -- Check the result expression of a scalar function against
2635 -- the subtype of the function by inserting a conversion.
2636 -- This conversion must eventually be performed for other
2637 -- classes of types, but for now it's only done for scalars.
2640 if Is_Scalar_Type
(T
) then
2641 Rewrite
(Exp
, Convert_To
(Return_Type
, Exp
));
2645 -- Implement the rules of 6.5(8-10), which require a tag check in
2646 -- the case of a limited tagged return type, and tag reassignment
2647 -- for nonlimited tagged results. These actions are needed when
2648 -- the return type is a specific tagged type and the result
2649 -- expression is a conversion or a formal parameter, because in
2650 -- that case the tag of the expression might differ from the tag
2651 -- of the specific result type.
2653 if Is_Tagged_Type
(Utyp
)
2654 and then not Is_Class_Wide_Type
(Utyp
)
2655 and then (Nkind
(Exp
) = N_Type_Conversion
2656 or else Nkind
(Exp
) = N_Unchecked_Type_Conversion
2657 or else (Is_Entity_Name
(Exp
)
2658 and then Ekind
(Entity
(Exp
)) in Formal_Kind
))
2660 -- When the return type is limited, perform a check that the
2661 -- tag of the result is the same as the tag of the return type.
2663 if Is_Limited_Type
(Return_Type
) then
2665 Make_Raise_Constraint_Error
(Loc
,
2669 Make_Selected_Component
(Loc
,
2670 Prefix
=> Duplicate_Subexpr
(Exp
),
2672 New_Reference_To
(Tag_Component
(Utyp
), Loc
)),
2674 Unchecked_Convert_To
(RTE
(RE_Tag
),
2676 (Access_Disp_Table
(Base_Type
(Utyp
)), Loc
))),
2677 Reason
=> CE_Tag_Check_Failed
));
2679 -- If the result type is a specific nonlimited tagged type,
2680 -- then we have to ensure that the tag of the result is that
2681 -- of the result type. This is handled by making a copy of the
2682 -- expression in the case where it might have a different tag,
2683 -- namely when the expression is a conversion or a formal
2684 -- parameter. We create a new object of the result type and
2685 -- initialize it from the expression, which will implicitly
2686 -- force the tag to be set appropriately.
2690 Make_Defining_Identifier
(Loc
, New_Internal_Name
('R'));
2691 Result_Exp
:= New_Reference_To
(Result_Id
, Loc
);
2694 Make_Object_Declaration
(Loc
,
2695 Defining_Identifier
=> Result_Id
,
2696 Object_Definition
=> New_Reference_To
(Return_Type
, Loc
),
2697 Constant_Present
=> True,
2698 Expression
=> Relocate_Node
(Exp
));
2700 Set_Assignment_OK
(Result_Obj
);
2701 Insert_Action
(Exp
, Result_Obj
);
2703 Rewrite
(Exp
, Result_Exp
);
2704 Analyze_And_Resolve
(Exp
, Return_Type
);
2708 -- Deal with returning variable length objects and controlled types
2710 -- Nothing to do if we are returning by reference, or this is not
2711 -- a type that requires special processing (indicated by the fact
2712 -- that it requires a cleanup scope for the secondary stack case)
2714 if Is_Return_By_Reference_Type
(T
)
2715 or else not Requires_Transient_Scope
(Return_Type
)
2719 -- Case of secondary stack not used
2721 elsif Function_Returns_With_DSP
(Scope_Id
) then
2723 -- Here what we need to do is to always return by reference, since
2724 -- we will return with the stack pointer depressed. We may need to
2725 -- do a copy to a local temporary before doing this return.
2727 No_Secondary_Stack_Case
: declare
2728 Local_Copy_Required
: Boolean := False;
2729 -- Set to True if a local copy is required
2731 Copy_Ent
: Entity_Id
;
2732 -- Used for the target entity if a copy is required
2735 -- Declaration used to create copy if needed
2737 procedure Test_Copy_Required
(Expr
: Node_Id
);
2738 -- Determines if Expr represents a return value for which a
2739 -- copy is required. More specifically, a copy is not required
2740 -- if Expr represents an object or component of an object that
2741 -- is either in the local subprogram frame, or is constant.
2742 -- If a copy is required, then Local_Copy_Required is set True.
2744 ------------------------
2745 -- Test_Copy_Required --
2746 ------------------------
2748 procedure Test_Copy_Required
(Expr
: Node_Id
) is
2752 -- If component, test prefix (object containing component)
2754 if Nkind
(Expr
) = N_Indexed_Component
2756 Nkind
(Expr
) = N_Selected_Component
2758 Test_Copy_Required
(Prefix
(Expr
));
2761 -- See if we have an entity name
2763 elsif Is_Entity_Name
(Expr
) then
2764 Ent
:= Entity
(Expr
);
2766 -- Constant entity is always OK, no copy required
2768 if Ekind
(Ent
) = E_Constant
then
2771 -- No copy required for local variable
2773 elsif Ekind
(Ent
) = E_Variable
2774 and then Scope
(Ent
) = Current_Subprogram
2780 -- All other cases require a copy
2782 Local_Copy_Required
:= True;
2783 end Test_Copy_Required
;
2785 -- Start of processing for No_Secondary_Stack_Case
2788 -- No copy needed if result is from a function call.
2789 -- In this case the result is already being returned by
2790 -- reference with the stack pointer depressed.
2792 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2793 -- the copy for array types if the constrained status of the
2794 -- target type is different from that of the expression.
2796 if Requires_Transient_Scope
(T
)
2798 (not Is_Array_Type
(T
)
2799 or else Is_Constrained
(T
) = Is_Constrained
(Return_Type
)
2800 or else Controlled_Type
(T
))
2801 and then Nkind
(Exp
) = N_Function_Call
2805 -- We always need a local copy for a controlled type, since
2806 -- we are required to finalize the local value before return.
2807 -- The copy will automatically include the required finalize.
2808 -- Moreover, gigi cannot make this copy, since we need special
2809 -- processing to ensure proper behavior for finalization.
2811 -- Note: the reason we are returning with a depressed stack
2812 -- pointer in the controlled case (even if the type involved
2813 -- is constrained) is that we must make a local copy to deal
2814 -- properly with the requirement that the local result be
2817 elsif Controlled_Type
(Utyp
) then
2819 Make_Defining_Identifier
(Loc
,
2820 Chars
=> New_Internal_Name
('R'));
2822 -- Build declaration to do the copy, and insert it, setting
2823 -- Assignment_OK, because we may be copying a limited type.
2824 -- In addition we set the special flag to inhibit finalize
2825 -- attachment if this is a controlled type (since this attach
2826 -- must be done by the caller, otherwise if we attach it here
2827 -- we will finalize the returned result prematurely).
2830 Make_Object_Declaration
(Loc
,
2831 Defining_Identifier
=> Copy_Ent
,
2832 Object_Definition
=> New_Occurrence_Of
(Return_Type
, Loc
),
2833 Expression
=> Relocate_Node
(Exp
));
2835 Set_Assignment_OK
(Decl
);
2836 Set_Delay_Finalize_Attach
(Decl
);
2837 Insert_Action
(N
, Decl
);
2839 -- Now the actual return uses the copied value
2841 Rewrite
(Exp
, New_Occurrence_Of
(Copy_Ent
, Loc
));
2842 Analyze_And_Resolve
(Exp
, Return_Type
);
2844 -- Since we have made the copy, gigi does not have to, so
2845 -- we set the By_Ref flag to prevent another copy being made.
2849 -- Non-controlled cases
2852 Test_Copy_Required
(Exp
);
2854 -- If a local copy is required, then gigi will make the
2855 -- copy, otherwise, we can return the result directly,
2856 -- so set By_Ref to suppress the gigi copy.
2858 if not Local_Copy_Required
then
2862 end No_Secondary_Stack_Case
;
2864 -- Here if secondary stack is used
2867 -- Make sure that no surrounding block will reclaim the
2868 -- secondary-stack on which we are going to put the result.
2869 -- Not only may this introduce secondary stack leaks but worse,
2870 -- if the reclamation is done too early, then the result we are
2871 -- returning may get clobbered. See example in 7417-003.
2874 S
: Entity_Id
:= Current_Scope
;
2877 while Ekind
(S
) = E_Block
or else Ekind
(S
) = E_Loop
loop
2878 Set_Sec_Stack_Needed_For_Return
(S
, True);
2879 S
:= Enclosing_Dynamic_Scope
(S
);
2883 -- Optimize the case where the result is a function call. In this
2884 -- case either the result is already on the secondary stack, or is
2885 -- already being returned with the stack pointer depressed and no
2886 -- further processing is required except to set the By_Ref flag to
2887 -- ensure that gigi does not attempt an extra unnecessary copy.
2888 -- (actually not just unnecessary but harmfully wrong in the case
2889 -- of a controlled type, where gigi does not know how to do a copy).
2890 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2891 -- the copy for array types if the constrained status of the
2892 -- target type is different from that of the expression.
2894 if Requires_Transient_Scope
(T
)
2896 (not Is_Array_Type
(T
)
2897 or else Is_Constrained
(T
) = Is_Constrained
(Return_Type
)
2898 or else Controlled_Type
(T
))
2899 and then Nkind
(Exp
) = N_Function_Call
2903 -- For controlled types, do the allocation on the sec-stack
2904 -- manually in order to call adjust at the right time
2905 -- type Anon1 is access Return_Type;
2906 -- for Anon1'Storage_pool use ss_pool;
2907 -- Anon2 : anon1 := new Return_Type'(expr);
2908 -- return Anon2.all;
2910 elsif Controlled_Type
(Utyp
) then
2912 Loc
: constant Source_Ptr
:= Sloc
(N
);
2913 Temp
: constant Entity_Id
:=
2914 Make_Defining_Identifier
(Loc
,
2915 Chars
=> New_Internal_Name
('R'));
2916 Acc_Typ
: constant Entity_Id
:=
2917 Make_Defining_Identifier
(Loc
,
2918 Chars
=> New_Internal_Name
('A'));
2919 Alloc_Node
: Node_Id
;
2922 Set_Ekind
(Acc_Typ
, E_Access_Type
);
2924 Set_Associated_Storage_Pool
(Acc_Typ
, RTE
(RE_SS_Pool
));
2927 Make_Allocator
(Loc
,
2929 Make_Qualified_Expression
(Loc
,
2930 Subtype_Mark
=> New_Reference_To
(Etype
(Exp
), Loc
),
2931 Expression
=> Relocate_Node
(Exp
)));
2933 Insert_List_Before_And_Analyze
(N
, New_List
(
2934 Make_Full_Type_Declaration
(Loc
,
2935 Defining_Identifier
=> Acc_Typ
,
2937 Make_Access_To_Object_Definition
(Loc
,
2938 Subtype_Indication
=>
2939 New_Reference_To
(Return_Type
, Loc
))),
2941 Make_Object_Declaration
(Loc
,
2942 Defining_Identifier
=> Temp
,
2943 Object_Definition
=> New_Reference_To
(Acc_Typ
, Loc
),
2944 Expression
=> Alloc_Node
)));
2947 Make_Explicit_Dereference
(Loc
,
2948 Prefix
=> New_Reference_To
(Temp
, Loc
)));
2950 Analyze_And_Resolve
(Exp
, Return_Type
);
2953 -- Otherwise use the gigi mechanism to allocate result on the
2957 Set_Storage_Pool
(N
, RTE
(RE_SS_Pool
));
2959 -- If we are generating code for the Java VM do not use
2960 -- SS_Allocate since everything is heap-allocated anyway.
2963 Set_Procedure_To_Call
(N
, RTE
(RE_SS_Allocate
));
2969 when RE_Not_Available
=>
2971 end Expand_N_Return_Statement
;
2973 ------------------------------
2974 -- Make_Tag_Ctrl_Assignment --
2975 ------------------------------
2977 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
is
2978 Loc
: constant Source_Ptr
:= Sloc
(N
);
2979 L
: constant Node_Id
:= Name
(N
);
2980 T
: constant Entity_Id
:= Underlying_Type
(Etype
(L
));
2982 Ctrl_Act
: constant Boolean := Controlled_Type
(T
)
2983 and then not No_Ctrl_Actions
(N
);
2985 Save_Tag
: constant Boolean := Is_Tagged_Type
(T
)
2986 and then not No_Ctrl_Actions
(N
)
2987 and then not Java_VM
;
2988 -- Tags are not saved and restored when Java_VM because JVM tags
2989 -- are represented implicitly in objects.
2992 Tag_Tmp
: Entity_Id
;
2993 Prev_Tmp
: Entity_Id
;
2994 Next_Tmp
: Entity_Id
;
2996 Ctrl_Ref2
: Node_Id
:= Empty
;
2997 Prev_Tmp2
: Entity_Id
:= Empty
; -- prevent warning
2998 Next_Tmp2
: Entity_Id
:= Empty
; -- prevent warning
3003 -- Finalize the target of the assignment when controlled.
3004 -- We have two exceptions here:
3006 -- 1. If we are in an init proc since it is an initialization
3007 -- more than an assignment
3009 -- 2. If the left-hand side is a temporary that was not initialized
3010 -- (or the parent part of a temporary since it is the case in
3011 -- extension aggregates). Such a temporary does not come from
3012 -- source. We must examine the original node for the prefix, because
3013 -- it may be a component of an entry formal, in which case it has
3014 -- been rewritten and does not appear to come from source either.
3016 -- Case of init proc
3018 if not Ctrl_Act
then
3021 -- The left hand side is an uninitialized temporary
3023 elsif Nkind
(L
) = N_Type_Conversion
3024 and then Is_Entity_Name
(Expression
(L
))
3025 and then No_Initialization
(Parent
(Entity
(Expression
(L
))))
3029 Append_List_To
(Res
,
3031 Ref
=> Duplicate_Subexpr_No_Checks
(L
),
3033 With_Detach
=> New_Reference_To
(Standard_False
, Loc
)));
3036 Next_Tmp
:= Make_Defining_Identifier
(Loc
, New_Internal_Name
('C'));
3038 -- Save the Tag in a local variable Tag_Tmp
3042 Make_Defining_Identifier
(Loc
, New_Internal_Name
('A'));
3045 Make_Object_Declaration
(Loc
,
3046 Defining_Identifier
=> Tag_Tmp
,
3047 Object_Definition
=> New_Reference_To
(RTE
(RE_Tag
), Loc
),
3049 Make_Selected_Component
(Loc
,
3050 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
3051 Selector_Name
=> New_Reference_To
(Tag_Component
(T
), Loc
))));
3053 -- Otherwise Tag_Tmp not used
3059 -- Save the Finalization Pointers in local variables Prev_Tmp and
3060 -- Next_Tmp. For objects with Has_Controlled_Component set, these
3061 -- pointers are in the Record_Controller and if it is also
3062 -- Is_Controlled, we need to save the object pointers as well.
3065 Ctrl_Ref
:= Duplicate_Subexpr_No_Checks
(L
);
3067 if Has_Controlled_Component
(T
) then
3069 Make_Selected_Component
(Loc
,
3072 New_Reference_To
(Controller_Component
(T
), Loc
));
3074 if Is_Controlled
(T
) then
3075 Ctrl_Ref2
:= Duplicate_Subexpr_No_Checks
(L
);
3079 Prev_Tmp
:= Make_Defining_Identifier
(Loc
, New_Internal_Name
('B'));
3082 Make_Object_Declaration
(Loc
,
3083 Defining_Identifier
=> Prev_Tmp
,
3085 Object_Definition
=>
3086 New_Reference_To
(RTE
(RE_Finalizable_Ptr
), Loc
),
3089 Make_Selected_Component
(Loc
,
3091 Unchecked_Convert_To
(RTE
(RE_Finalizable
), Ctrl_Ref
),
3092 Selector_Name
=> Make_Identifier
(Loc
, Name_Prev
))));
3094 Next_Tmp
:= Make_Defining_Identifier
(Loc
, New_Internal_Name
('C'));
3097 Make_Object_Declaration
(Loc
,
3098 Defining_Identifier
=> Next_Tmp
,
3100 Object_Definition
=>
3101 New_Reference_To
(RTE
(RE_Finalizable_Ptr
), Loc
),
3104 Make_Selected_Component
(Loc
,
3106 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
3107 New_Copy_Tree
(Ctrl_Ref
)),
3108 Selector_Name
=> Make_Identifier
(Loc
, Name_Next
))));
3110 if Present
(Ctrl_Ref2
) then
3112 Make_Defining_Identifier
(Loc
, New_Internal_Name
('B'));
3115 Make_Object_Declaration
(Loc
,
3116 Defining_Identifier
=> Prev_Tmp2
,
3118 Object_Definition
=>
3119 New_Reference_To
(RTE
(RE_Finalizable_Ptr
), Loc
),
3122 Make_Selected_Component
(Loc
,
3124 Unchecked_Convert_To
(RTE
(RE_Finalizable
), Ctrl_Ref2
),
3125 Selector_Name
=> Make_Identifier
(Loc
, Name_Prev
))));
3128 Make_Defining_Identifier
(Loc
, New_Internal_Name
('C'));
3131 Make_Object_Declaration
(Loc
,
3132 Defining_Identifier
=> Next_Tmp2
,
3134 Object_Definition
=>
3135 New_Reference_To
(RTE
(RE_Finalizable_Ptr
), Loc
),
3138 Make_Selected_Component
(Loc
,
3140 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
3141 New_Copy_Tree
(Ctrl_Ref2
)),
3142 Selector_Name
=> Make_Identifier
(Loc
, Name_Next
))));
3145 -- If not controlled type, then Prev_Tmp and Ctrl_Ref unused
3152 -- Do the Assignment
3154 Append_To
(Res
, Relocate_Node
(N
));
3160 Make_Assignment_Statement
(Loc
,
3162 Make_Selected_Component
(Loc
,
3163 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
3164 Selector_Name
=> New_Reference_To
(Tag_Component
(T
), Loc
)),
3165 Expression
=> New_Reference_To
(Tag_Tmp
, Loc
)));
3168 -- Restore the finalization pointers
3172 Make_Assignment_Statement
(Loc
,
3174 Make_Selected_Component
(Loc
,
3176 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
3177 New_Copy_Tree
(Ctrl_Ref
)),
3178 Selector_Name
=> Make_Identifier
(Loc
, Name_Prev
)),
3179 Expression
=> New_Reference_To
(Prev_Tmp
, Loc
)));
3182 Make_Assignment_Statement
(Loc
,
3184 Make_Selected_Component
(Loc
,
3186 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
3187 New_Copy_Tree
(Ctrl_Ref
)),
3188 Selector_Name
=> Make_Identifier
(Loc
, Name_Next
)),
3189 Expression
=> New_Reference_To
(Next_Tmp
, Loc
)));
3191 if Present
(Ctrl_Ref2
) then
3193 Make_Assignment_Statement
(Loc
,
3195 Make_Selected_Component
(Loc
,
3197 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
3198 New_Copy_Tree
(Ctrl_Ref2
)),
3199 Selector_Name
=> Make_Identifier
(Loc
, Name_Prev
)),
3200 Expression
=> New_Reference_To
(Prev_Tmp2
, Loc
)));
3203 Make_Assignment_Statement
(Loc
,
3205 Make_Selected_Component
(Loc
,
3207 Unchecked_Convert_To
(RTE
(RE_Finalizable
),
3208 New_Copy_Tree
(Ctrl_Ref2
)),
3209 Selector_Name
=> Make_Identifier
(Loc
, Name_Next
)),
3210 Expression
=> New_Reference_To
(Next_Tmp2
, Loc
)));
3214 -- Adjust the target after the assignment when controlled. (not in
3215 -- the init proc since it is an initialization more than an
3219 Append_List_To
(Res
,
3221 Ref
=> Duplicate_Subexpr_Move_Checks
(L
),
3223 Flist_Ref
=> New_Reference_To
(RTE
(RE_Global_Final_List
), Loc
),
3224 With_Attach
=> Make_Integer_Literal
(Loc
, 0)));
3230 when RE_Not_Available
=>
3232 end Make_Tag_Ctrl_Assignment
;
3234 ------------------------------------
3235 -- Possible_Bit_Aligned_Component --
3236 ------------------------------------
3238 function Possible_Bit_Aligned_Component
(N
: Node_Id
) return Boolean is
3242 -- Case of indexed component
3244 when N_Indexed_Component
=>
3246 P
: constant Node_Id
:= Prefix
(N
);
3247 Ptyp
: constant Entity_Id
:= Etype
(P
);
3250 -- If we know the component size and it is less than 64, then
3251 -- we are definitely OK. The back end always does assignment
3252 -- of misaligned small objects correctly.
3254 if Known_Static_Component_Size
(Ptyp
)
3255 and then Component_Size
(Ptyp
) <= 64
3259 -- Otherwise, we need to test the prefix, to see if we are
3260 -- indexing from a possibly unaligned component.
3263 return Possible_Bit_Aligned_Component
(P
);
3267 -- Case of selected component
3269 when N_Selected_Component
=>
3271 P
: constant Node_Id
:= Prefix
(N
);
3272 Comp
: constant Entity_Id
:= Entity
(Selector_Name
(N
));
3275 -- If there is no component clause, then we are in the clear
3276 -- since the back end will never misalign a large component
3277 -- unless it is forced to do so. In the clear means we need
3278 -- only the recursive test on the prefix.
3280 if No
(Component_Clause
(Comp
)) then
3281 return Possible_Bit_Aligned_Component
(P
);
3283 -- Otherwise we have a component clause, which means that
3284 -- the Esize and Normalized_First_Bit fields are set and
3285 -- contain static values known at compile time.
3288 -- If we know that we have a small (64 bits or less) record
3289 -- or bit-packed array, then everything is fine, since the
3290 -- back end can handle these cases correctly.
3292 if Esize
(Comp
) <= 64
3293 and then (Is_Record_Type
(Etype
(Comp
))
3295 Is_Bit_Packed_Array
(Etype
(Comp
)))
3299 -- Otherwise if the component is not byte aligned, we
3300 -- know we have the nasty unaligned case.
3302 elsif Normalized_First_Bit
(Comp
) /= Uint_0
3303 or else Esize
(Comp
) mod System_Storage_Unit
/= Uint_0
3307 -- If we are large and byte aligned, then OK at this level
3308 -- but we still need to test our prefix recursively.
3311 return Possible_Bit_Aligned_Component
(P
);
3316 -- If we have neither a record nor array component, it means that
3317 -- we have fallen off the top testing prefixes recursively, and
3318 -- we now have a stand alone object, where we don't have a problem
3324 end Possible_Bit_Aligned_Component
;