1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2012, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Aspects
; use Aspects
;
27 with Atree
; use Atree
;
28 with Checks
; use Checks
;
29 with Debug
; use Debug
;
30 with Einfo
; use Einfo
;
31 with Elists
; use Elists
;
32 with Errout
; use Errout
;
33 with Exp_Aggr
; use Exp_Aggr
;
34 with Exp_Ch6
; use Exp_Ch6
;
35 with Exp_Ch7
; use Exp_Ch7
;
36 with Exp_Ch11
; use Exp_Ch11
;
37 with Exp_Dbug
; use Exp_Dbug
;
38 with Exp_Pakd
; use Exp_Pakd
;
39 with Exp_Tss
; use Exp_Tss
;
40 with Exp_Util
; use Exp_Util
;
41 with Namet
; use Namet
;
42 with Nlists
; use Nlists
;
43 with Nmake
; use Nmake
;
45 with Restrict
; use Restrict
;
46 with Rident
; use Rident
;
47 with Rtsfind
; use Rtsfind
;
48 with Sinfo
; use Sinfo
;
50 with Sem_Aux
; use Sem_Aux
;
51 with Sem_Ch3
; use Sem_Ch3
;
52 with Sem_Ch8
; use Sem_Ch8
;
53 with Sem_Ch13
; use Sem_Ch13
;
54 with Sem_Eval
; use Sem_Eval
;
55 with Sem_Res
; use Sem_Res
;
56 with Sem_Util
; use Sem_Util
;
57 with Snames
; use Snames
;
58 with Stand
; use Stand
;
59 with Stringt
; use Stringt
;
60 with Targparm
; use Targparm
;
61 with Tbuild
; use Tbuild
;
62 with Validsw
; use Validsw
;
64 package body Exp_Ch5
is
66 function Change_Of_Representation
(N
: Node_Id
) return Boolean;
67 -- Determine if the right hand side of assignment N is a type conversion
68 -- which requires a change of representation. Called only for the array
71 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
);
72 -- N is an assignment which assigns an array value. This routine process
73 -- the various special cases and checks required for such assignments,
74 -- including change of representation. Rhs is normally simply the right
75 -- hand side of the assignment, except that if the right hand side is a
76 -- type conversion or a qualified expression, then the RHS is the actual
77 -- expression inside any such type conversions or qualifications.
79 function Expand_Assign_Array_Loop
86 Rev
: Boolean) return Node_Id
;
87 -- N is an assignment statement which assigns an array value. This routine
88 -- expands the assignment into a loop (or nested loops for the case of a
89 -- multi-dimensional array) to do the assignment component by component.
90 -- Larray and Rarray are the entities of the actual arrays on the left
91 -- hand and right hand sides. L_Type and R_Type are the types of these
92 -- arrays (which may not be the same, due to either sliding, or to a
93 -- change of representation case). Ndim is the number of dimensions and
94 -- the parameter Rev indicates if the loops run normally (Rev = False),
95 -- or reversed (Rev = True). The value returned is the constructed
96 -- loop statement. Auxiliary declarations are inserted before node N
97 -- using the standard Insert_Actions mechanism.
99 procedure Expand_Assign_Record
(N
: Node_Id
);
100 -- N is an assignment of a non-tagged record value. This routine handles
101 -- the case where the assignment must be made component by component,
102 -- either because the target is not byte aligned, or there is a change
103 -- of representation, or when we have a tagged type with a representation
104 -- clause (this last case is required because holes in the tagged type
105 -- might be filled with components from child types).
107 procedure Expand_Iterator_Loop
(N
: Node_Id
);
108 -- Expand loop over arrays and containers that uses the form "for X of C"
109 -- with an optional subtype mark, or "for Y in C".
111 procedure Expand_Iterator_Loop_Over_Array
(N
: Node_Id
);
112 -- Expand loop over arrays that uses the form "for X of C"
114 procedure Expand_Loop_Entry_Attributes
(N
: Node_Id
);
115 -- Given a loop statement subject to at least one Loop_Entry attribute,
116 -- expand both the loop and all related Loop_Entry references.
118 procedure Expand_Predicated_Loop
(N
: Node_Id
);
119 -- Expand for loop over predicated subtype
121 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
;
122 -- Generate the necessary code for controlled and tagged assignment, that
123 -- is to say, finalization of the target before, adjustment of the target
124 -- after and save and restore of the tag and finalization pointers which
125 -- are not 'part of the value' and must not be changed upon assignment. N
126 -- is the original Assignment node.
128 ------------------------------
129 -- Change_Of_Representation --
130 ------------------------------
132 function Change_Of_Representation
(N
: Node_Id
) return Boolean is
133 Rhs
: constant Node_Id
:= Expression
(N
);
136 Nkind
(Rhs
) = N_Type_Conversion
138 not Same_Representation
(Etype
(Rhs
), Etype
(Expression
(Rhs
)));
139 end Change_Of_Representation
;
141 -------------------------
142 -- Expand_Assign_Array --
143 -------------------------
145 -- There are two issues here. First, do we let Gigi do a block move, or
146 -- do we expand out into a loop? Second, we need to set the two flags
147 -- Forwards_OK and Backwards_OK which show whether the block move (or
148 -- corresponding loops) can be legitimately done in a forwards (low to
149 -- high) or backwards (high to low) manner.
151 procedure Expand_Assign_Array
(N
: Node_Id
; Rhs
: Node_Id
) is
152 Loc
: constant Source_Ptr
:= Sloc
(N
);
154 Lhs
: constant Node_Id
:= Name
(N
);
156 Act_Lhs
: constant Node_Id
:= Get_Referenced_Object
(Lhs
);
157 Act_Rhs
: Node_Id
:= Get_Referenced_Object
(Rhs
);
159 L_Type
: constant Entity_Id
:=
160 Underlying_Type
(Get_Actual_Subtype
(Act_Lhs
));
161 R_Type
: Entity_Id
:=
162 Underlying_Type
(Get_Actual_Subtype
(Act_Rhs
));
164 L_Slice
: constant Boolean := Nkind
(Act_Lhs
) = N_Slice
;
165 R_Slice
: constant Boolean := Nkind
(Act_Rhs
) = N_Slice
;
167 Crep
: constant Boolean := Change_Of_Representation
(N
);
172 Ndim
: constant Pos
:= Number_Dimensions
(L_Type
);
174 Loop_Required
: Boolean := False;
175 -- This switch is set to True if the array move must be done using
176 -- an explicit front end generated loop.
178 procedure Apply_Dereference
(Arg
: Node_Id
);
179 -- If the argument is an access to an array, and the assignment is
180 -- converted into a procedure call, apply explicit dereference.
182 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean;
183 -- Test if Exp is a reference to an array whose declaration has
184 -- an address clause, or it is a slice of such an array.
186 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean;
187 -- Test if Exp is a reference to an array which is either a formal
188 -- parameter or a slice of a formal parameter. These are the cases
189 -- where hidden aliasing can occur.
191 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean;
192 -- Determine if Exp is a reference to an array variable which is other
193 -- than an object defined in the current scope, or a slice of such
194 -- an object. Such objects can be aliased to parameters (unlike local
195 -- array references).
197 -----------------------
198 -- Apply_Dereference --
199 -----------------------
201 procedure Apply_Dereference
(Arg
: Node_Id
) is
202 Typ
: constant Entity_Id
:= Etype
(Arg
);
204 if Is_Access_Type
(Typ
) then
205 Rewrite
(Arg
, Make_Explicit_Dereference
(Loc
,
206 Prefix
=> Relocate_Node
(Arg
)));
207 Analyze_And_Resolve
(Arg
, Designated_Type
(Typ
));
209 end Apply_Dereference
;
211 ------------------------
212 -- Has_Address_Clause --
213 ------------------------
215 function Has_Address_Clause
(Exp
: Node_Id
) return Boolean is
218 (Is_Entity_Name
(Exp
) and then
219 Present
(Address_Clause
(Entity
(Exp
))))
221 (Nkind
(Exp
) = N_Slice
and then Has_Address_Clause
(Prefix
(Exp
)));
222 end Has_Address_Clause
;
224 ---------------------
225 -- Is_Formal_Array --
226 ---------------------
228 function Is_Formal_Array
(Exp
: Node_Id
) return Boolean is
231 (Is_Entity_Name
(Exp
) and then Is_Formal
(Entity
(Exp
)))
233 (Nkind
(Exp
) = N_Slice
and then Is_Formal_Array
(Prefix
(Exp
)));
236 ------------------------
237 -- Is_Non_Local_Array --
238 ------------------------
240 function Is_Non_Local_Array
(Exp
: Node_Id
) return Boolean is
242 return (Is_Entity_Name
(Exp
)
243 and then Scope
(Entity
(Exp
)) /= Current_Scope
)
244 or else (Nkind
(Exp
) = N_Slice
245 and then Is_Non_Local_Array
(Prefix
(Exp
)));
246 end Is_Non_Local_Array
;
248 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
250 Lhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Lhs
);
251 Rhs_Formal
: constant Boolean := Is_Formal_Array
(Act_Rhs
);
253 Lhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Lhs
);
254 Rhs_Non_Local_Var
: constant Boolean := Is_Non_Local_Array
(Act_Rhs
);
256 -- Start of processing for Expand_Assign_Array
259 -- Deal with length check. Note that the length check is done with
260 -- respect to the right hand side as given, not a possible underlying
261 -- renamed object, since this would generate incorrect extra checks.
263 Apply_Length_Check
(Rhs
, L_Type
);
265 -- We start by assuming that the move can be done in either direction,
266 -- i.e. that the two sides are completely disjoint.
268 Set_Forwards_OK
(N
, True);
269 Set_Backwards_OK
(N
, True);
271 -- Normally it is only the slice case that can lead to overlap, and
272 -- explicit checks for slices are made below. But there is one case
273 -- where the slice can be implicit and invisible to us: when we have a
274 -- one dimensional array, and either both operands are parameters, or
275 -- one is a parameter (which can be a slice passed by reference) and the
276 -- other is a non-local variable. In this case the parameter could be a
277 -- slice that overlaps with the other operand.
279 -- However, if the array subtype is a constrained first subtype in the
280 -- parameter case, then we don't have to worry about overlap, since
281 -- slice assignments aren't possible (other than for a slice denoting
284 -- Note: No overlap is possible if there is a change of representation,
285 -- so we can exclude this case.
290 ((Lhs_Formal
and Rhs_Formal
)
292 (Lhs_Formal
and Rhs_Non_Local_Var
)
294 (Rhs_Formal
and Lhs_Non_Local_Var
))
296 (not Is_Constrained
(Etype
(Lhs
))
297 or else not Is_First_Subtype
(Etype
(Lhs
)))
299 -- In the case of compiling for the Java or .NET Virtual Machine,
300 -- slices are always passed by making a copy, so we don't have to
301 -- worry about overlap. We also want to prevent generation of "<"
302 -- comparisons for array addresses, since that's a meaningless
303 -- operation on the VM.
305 and then VM_Target
= No_VM
307 Set_Forwards_OK
(N
, False);
308 Set_Backwards_OK
(N
, False);
310 -- Note: the bit-packed case is not worrisome here, since if we have
311 -- a slice passed as a parameter, it is always aligned on a byte
312 -- boundary, and if there are no explicit slices, the assignment
313 -- can be performed directly.
316 -- If either operand has an address clause clear Backwards_OK and
317 -- Forwards_OK, since we cannot tell if the operands overlap. We
318 -- exclude this treatment when Rhs is an aggregate, since we know
319 -- that overlap can't occur.
321 if (Has_Address_Clause
(Lhs
) and then Nkind
(Rhs
) /= N_Aggregate
)
322 or else Has_Address_Clause
(Rhs
)
324 Set_Forwards_OK
(N
, False);
325 Set_Backwards_OK
(N
, False);
328 -- We certainly must use a loop for change of representation and also
329 -- we use the operand of the conversion on the right hand side as the
330 -- effective right hand side (the component types must match in this
334 Act_Rhs
:= Get_Referenced_Object
(Rhs
);
335 R_Type
:= Get_Actual_Subtype
(Act_Rhs
);
336 Loop_Required
:= True;
338 -- We require a loop if the left side is possibly bit unaligned
340 elsif Possible_Bit_Aligned_Component
(Lhs
)
342 Possible_Bit_Aligned_Component
(Rhs
)
344 Loop_Required
:= True;
346 -- Arrays with controlled components are expanded into a loop to force
347 -- calls to Adjust at the component level.
349 elsif Has_Controlled_Component
(L_Type
) then
350 Loop_Required
:= True;
352 -- If object is atomic, we cannot tolerate a loop
354 elsif Is_Atomic_Object
(Act_Lhs
)
356 Is_Atomic_Object
(Act_Rhs
)
360 -- Loop is required if we have atomic components since we have to
361 -- be sure to do any accesses on an element by element basis.
363 elsif Has_Atomic_Components
(L_Type
)
364 or else Has_Atomic_Components
(R_Type
)
365 or else Is_Atomic
(Component_Type
(L_Type
))
366 or else Is_Atomic
(Component_Type
(R_Type
))
368 Loop_Required
:= True;
370 -- Case where no slice is involved
372 elsif not L_Slice
and not R_Slice
then
374 -- The following code deals with the case of unconstrained bit packed
375 -- arrays. The problem is that the template for such arrays contains
376 -- the bounds of the actual source level array, but the copy of an
377 -- entire array requires the bounds of the underlying array. It would
378 -- be nice if the back end could take care of this, but right now it
379 -- does not know how, so if we have such a type, then we expand out
380 -- into a loop, which is inefficient but works correctly. If we don't
381 -- do this, we get the wrong length computed for the array to be
382 -- moved. The two cases we need to worry about are:
384 -- Explicit dereference of an unconstrained packed array type as in
385 -- the following example:
388 -- type BITS is array(INTEGER range <>) of BOOLEAN;
389 -- pragma PACK(BITS);
390 -- type A is access BITS;
393 -- P1 := new BITS (1 .. 65_535);
394 -- P2 := new BITS (1 .. 65_535);
398 -- A formal parameter reference with an unconstrained bit array type
399 -- is the other case we need to worry about (here we assume the same
400 -- BITS type declared above):
402 -- procedure Write_All (File : out BITS; Contents : BITS);
404 -- File.Storage := Contents;
407 -- We expand to a loop in either of these two cases
409 -- Question for future thought. Another potentially more efficient
410 -- approach would be to create the actual subtype, and then do an
411 -- unchecked conversion to this actual subtype ???
413 Check_Unconstrained_Bit_Packed_Array
: declare
415 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean;
416 -- Function to perform required test for the first case, above
417 -- (dereference of an unconstrained bit packed array).
419 -----------------------
420 -- Is_UBPA_Reference --
421 -----------------------
423 function Is_UBPA_Reference
(Opnd
: Node_Id
) return Boolean is
424 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Opnd
));
426 Des_Type
: Entity_Id
;
429 if Present
(Packed_Array_Type
(Typ
))
430 and then Is_Array_Type
(Packed_Array_Type
(Typ
))
431 and then not Is_Constrained
(Packed_Array_Type
(Typ
))
435 elsif Nkind
(Opnd
) = N_Explicit_Dereference
then
436 P_Type
:= Underlying_Type
(Etype
(Prefix
(Opnd
)));
438 if not Is_Access_Type
(P_Type
) then
442 Des_Type
:= Designated_Type
(P_Type
);
444 Is_Bit_Packed_Array
(Des_Type
)
445 and then not Is_Constrained
(Des_Type
);
451 end Is_UBPA_Reference
;
453 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
456 if Is_UBPA_Reference
(Lhs
)
458 Is_UBPA_Reference
(Rhs
)
460 Loop_Required
:= True;
462 -- Here if we do not have the case of a reference to a bit packed
463 -- unconstrained array case. In this case gigi can most certainly
464 -- handle the assignment if a forwards move is allowed.
466 -- (could it handle the backwards case also???)
468 elsif Forwards_OK
(N
) then
471 end Check_Unconstrained_Bit_Packed_Array
;
473 -- The back end can always handle the assignment if the right side is a
474 -- string literal (note that overlap is definitely impossible in this
475 -- case). If the type is packed, a string literal is always converted
476 -- into an aggregate, except in the case of a null slice, for which no
477 -- aggregate can be written. In that case, rewrite the assignment as a
478 -- null statement, a length check has already been emitted to verify
479 -- that the range of the left-hand side is empty.
481 -- Note that this code is not executed if we have an assignment of a
482 -- string literal to a non-bit aligned component of a record, a case
483 -- which cannot be handled by the backend.
485 elsif Nkind
(Rhs
) = N_String_Literal
then
486 if String_Length
(Strval
(Rhs
)) = 0
487 and then Is_Bit_Packed_Array
(L_Type
)
489 Rewrite
(N
, Make_Null_Statement
(Loc
));
495 -- If either operand is bit packed, then we need a loop, since we can't
496 -- be sure that the slice is byte aligned. Similarly, if either operand
497 -- is a possibly unaligned slice, then we need a loop (since the back
498 -- end cannot handle unaligned slices).
500 elsif Is_Bit_Packed_Array
(L_Type
)
501 or else Is_Bit_Packed_Array
(R_Type
)
502 or else Is_Possibly_Unaligned_Slice
(Lhs
)
503 or else Is_Possibly_Unaligned_Slice
(Rhs
)
505 Loop_Required
:= True;
507 -- If we are not bit-packed, and we have only one slice, then no overlap
508 -- is possible except in the parameter case, so we can let the back end
511 elsif not (L_Slice
and R_Slice
) then
512 if Forwards_OK
(N
) then
517 -- If the right-hand side is a string literal, introduce a temporary for
518 -- it, for use in the generated loop that will follow.
520 if Nkind
(Rhs
) = N_String_Literal
then
522 Temp
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T', Rhs
);
527 Make_Object_Declaration
(Loc
,
528 Defining_Identifier
=> Temp
,
529 Object_Definition
=> New_Occurrence_Of
(L_Type
, Loc
),
530 Expression
=> Relocate_Node
(Rhs
));
532 Insert_Action
(N
, Decl
);
533 Rewrite
(Rhs
, New_Occurrence_Of
(Temp
, Loc
));
534 R_Type
:= Etype
(Temp
);
538 -- Come here to complete the analysis
540 -- Loop_Required: Set to True if we know that a loop is required
541 -- regardless of overlap considerations.
543 -- Forwards_OK: Set to False if we already know that a forwards
544 -- move is not safe, else set to True.
546 -- Backwards_OK: Set to False if we already know that a backwards
547 -- move is not safe, else set to True
549 -- Our task at this stage is to complete the overlap analysis, which can
550 -- result in possibly setting Forwards_OK or Backwards_OK to False, and
551 -- then generating the final code, either by deciding that it is OK
552 -- after all to let Gigi handle it, or by generating appropriate code
556 L_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(L_Type
));
557 R_Index_Typ
: constant Node_Id
:= Etype
(First_Index
(R_Type
));
559 Left_Lo
: constant Node_Id
:= Type_Low_Bound
(L_Index_Typ
);
560 Left_Hi
: constant Node_Id
:= Type_High_Bound
(L_Index_Typ
);
561 Right_Lo
: constant Node_Id
:= Type_Low_Bound
(R_Index_Typ
);
562 Right_Hi
: constant Node_Id
:= Type_High_Bound
(R_Index_Typ
);
564 Act_L_Array
: Node_Id
;
565 Act_R_Array
: Node_Id
;
571 Cresult
: Compare_Result
;
574 -- Get the expressions for the arrays. If we are dealing with a
575 -- private type, then convert to the underlying type. We can do
576 -- direct assignments to an array that is a private type, but we
577 -- cannot assign to elements of the array without this extra
578 -- unchecked conversion.
580 -- Note: We propagate Parent to the conversion nodes to generate
581 -- a well-formed subtree.
583 if Nkind
(Act_Lhs
) = N_Slice
then
584 Larray
:= Prefix
(Act_Lhs
);
588 if Is_Private_Type
(Etype
(Larray
)) then
590 Par
: constant Node_Id
:= Parent
(Larray
);
594 (Underlying_Type
(Etype
(Larray
)), Larray
);
595 Set_Parent
(Larray
, Par
);
600 if Nkind
(Act_Rhs
) = N_Slice
then
601 Rarray
:= Prefix
(Act_Rhs
);
605 if Is_Private_Type
(Etype
(Rarray
)) then
607 Par
: constant Node_Id
:= Parent
(Rarray
);
611 (Underlying_Type
(Etype
(Rarray
)), Rarray
);
612 Set_Parent
(Rarray
, Par
);
617 -- If both sides are slices, we must figure out whether it is safe
618 -- to do the move in one direction or the other. It is always safe
619 -- if there is a change of representation since obviously two arrays
620 -- with different representations cannot possibly overlap.
622 if (not Crep
) and L_Slice
and R_Slice
then
623 Act_L_Array
:= Get_Referenced_Object
(Prefix
(Act_Lhs
));
624 Act_R_Array
:= Get_Referenced_Object
(Prefix
(Act_Rhs
));
626 -- If both left and right hand arrays are entity names, and refer
627 -- to different entities, then we know that the move is safe (the
628 -- two storage areas are completely disjoint).
630 if Is_Entity_Name
(Act_L_Array
)
631 and then Is_Entity_Name
(Act_R_Array
)
632 and then Entity
(Act_L_Array
) /= Entity
(Act_R_Array
)
636 -- Otherwise, we assume the worst, which is that the two arrays
637 -- are the same array. There is no need to check if we know that
638 -- is the case, because if we don't know it, we still have to
641 -- Generally if the same array is involved, then we have an
642 -- overlapping case. We will have to really assume the worst (i.e.
643 -- set neither of the OK flags) unless we can determine the lower
644 -- or upper bounds at compile time and compare them.
649 (Left_Lo
, Right_Lo
, Assume_Valid
=> True);
651 if Cresult
= Unknown
then
654 (Left_Hi
, Right_Hi
, Assume_Valid
=> True);
658 when LT | LE | EQ
=> Set_Backwards_OK
(N
, False);
659 when GT | GE
=> Set_Forwards_OK
(N
, False);
660 when NE | Unknown
=> Set_Backwards_OK
(N
, False);
661 Set_Forwards_OK
(N
, False);
666 -- If after that analysis Loop_Required is False, meaning that we
667 -- have not discovered some non-overlap reason for requiring a loop,
668 -- then the outcome depends on the capabilities of the back end.
670 if not Loop_Required
then
672 -- The GCC back end can deal with all cases of overlap by falling
673 -- back to memmove if it cannot use a more efficient approach.
675 if VM_Target
= No_VM
and not AAMP_On_Target
then
678 -- Assume other back ends can handle it if Forwards_OK is set
680 elsif Forwards_OK
(N
) then
683 -- If Forwards_OK is not set, the back end will need something
684 -- like memmove to handle the move. For now, this processing is
685 -- activated using the .s debug flag (-gnatd.s).
687 elsif Debug_Flag_Dot_S
then
692 -- At this stage we have to generate an explicit loop, and we have
693 -- the following cases:
695 -- Forwards_OK = True
697 -- Rnn : right_index := right_index'First;
698 -- for Lnn in left-index loop
699 -- left (Lnn) := right (Rnn);
700 -- Rnn := right_index'Succ (Rnn);
703 -- Note: the above code MUST be analyzed with checks off, because
704 -- otherwise the Succ could overflow. But in any case this is more
707 -- Forwards_OK = False, Backwards_OK = True
709 -- Rnn : right_index := right_index'Last;
710 -- for Lnn in reverse left-index loop
711 -- left (Lnn) := right (Rnn);
712 -- Rnn := right_index'Pred (Rnn);
715 -- Note: the above code MUST be analyzed with checks off, because
716 -- otherwise the Pred could overflow. But in any case this is more
719 -- Forwards_OK = Backwards_OK = False
721 -- This only happens if we have the same array on each side. It is
722 -- possible to create situations using overlays that violate this,
723 -- but we simply do not promise to get this "right" in this case.
725 -- There are two possible subcases. If the No_Implicit_Conditionals
726 -- restriction is set, then we generate the following code:
729 -- T : constant <operand-type> := rhs;
734 -- If implicit conditionals are permitted, then we generate:
736 -- if Left_Lo <= Right_Lo then
737 -- <code for Forwards_OK = True above>
739 -- <code for Backwards_OK = True above>
742 -- In order to detect possible aliasing, we examine the renamed
743 -- expression when the source or target is a renaming. However,
744 -- the renaming may be intended to capture an address that may be
745 -- affected by subsequent code, and therefore we must recover
746 -- the actual entity for the expansion that follows, not the
747 -- object it renames. In particular, if source or target designate
748 -- a portion of a dynamically allocated object, the pointer to it
749 -- may be reassigned but the renaming preserves the proper location.
751 if Is_Entity_Name
(Rhs
)
753 Nkind
(Parent
(Entity
(Rhs
))) = N_Object_Renaming_Declaration
754 and then Nkind
(Act_Rhs
) = N_Slice
759 if Is_Entity_Name
(Lhs
)
761 Nkind
(Parent
(Entity
(Lhs
))) = N_Object_Renaming_Declaration
762 and then Nkind
(Act_Lhs
) = N_Slice
767 -- Cases where either Forwards_OK or Backwards_OK is true
769 if Forwards_OK
(N
) or else Backwards_OK
(N
) then
770 if Needs_Finalization
(Component_Type
(L_Type
))
771 and then Base_Type
(L_Type
) = Base_Type
(R_Type
)
773 and then not No_Ctrl_Actions
(N
)
776 Proc
: constant Entity_Id
:=
777 TSS
(Base_Type
(L_Type
), TSS_Slice_Assign
);
781 Apply_Dereference
(Larray
);
782 Apply_Dereference
(Rarray
);
783 Actuals
:= New_List
(
784 Duplicate_Subexpr
(Larray
, Name_Req
=> True),
785 Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
786 Duplicate_Subexpr
(Left_Lo
, Name_Req
=> True),
787 Duplicate_Subexpr
(Left_Hi
, Name_Req
=> True),
788 Duplicate_Subexpr
(Right_Lo
, Name_Req
=> True),
789 Duplicate_Subexpr
(Right_Hi
, Name_Req
=> True));
793 Boolean_Literals
(not Forwards_OK
(N
)), Loc
));
796 Make_Procedure_Call_Statement
(Loc
,
797 Name
=> New_Reference_To
(Proc
, Loc
),
798 Parameter_Associations
=> Actuals
));
803 Expand_Assign_Array_Loop
804 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
805 Rev
=> not Forwards_OK
(N
)));
808 -- Case of both are false with No_Implicit_Conditionals
810 elsif Restriction_Active
(No_Implicit_Conditionals
) then
812 T
: constant Entity_Id
:=
813 Make_Defining_Identifier
(Loc
, Chars
=> Name_T
);
817 Make_Block_Statement
(Loc
,
818 Declarations
=> New_List
(
819 Make_Object_Declaration
(Loc
,
820 Defining_Identifier
=> T
,
821 Constant_Present
=> True,
823 New_Occurrence_Of
(Etype
(Rhs
), Loc
),
824 Expression
=> Relocate_Node
(Rhs
))),
826 Handled_Statement_Sequence
=>
827 Make_Handled_Sequence_Of_Statements
(Loc
,
828 Statements
=> New_List
(
829 Make_Assignment_Statement
(Loc
,
830 Name
=> Relocate_Node
(Lhs
),
831 Expression
=> New_Occurrence_Of
(T
, Loc
))))));
834 -- Case of both are false with implicit conditionals allowed
837 -- Before we generate this code, we must ensure that the left and
838 -- right side array types are defined. They may be itypes, and we
839 -- cannot let them be defined inside the if, since the first use
840 -- in the then may not be executed.
842 Ensure_Defined
(L_Type
, N
);
843 Ensure_Defined
(R_Type
, N
);
845 -- We normally compare addresses to find out which way round to
846 -- do the loop, since this is reliable, and handles the cases of
847 -- parameters, conversions etc. But we can't do that in the bit
848 -- packed case or the VM case, because addresses don't work there.
850 if not Is_Bit_Packed_Array
(L_Type
) and then VM_Target
= No_VM
then
854 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
855 Make_Attribute_Reference
(Loc
,
857 Make_Indexed_Component
(Loc
,
859 Duplicate_Subexpr_Move_Checks
(Larray
, True),
860 Expressions
=> New_List
(
861 Make_Attribute_Reference
(Loc
,
865 Attribute_Name
=> Name_First
))),
866 Attribute_Name
=> Name_Address
)),
869 Unchecked_Convert_To
(RTE
(RE_Integer_Address
),
870 Make_Attribute_Reference
(Loc
,
872 Make_Indexed_Component
(Loc
,
874 Duplicate_Subexpr_Move_Checks
(Rarray
, True),
875 Expressions
=> New_List
(
876 Make_Attribute_Reference
(Loc
,
880 Attribute_Name
=> Name_First
))),
881 Attribute_Name
=> Name_Address
)));
883 -- For the bit packed and VM cases we use the bounds. That's OK,
884 -- because we don't have to worry about parameters, since they
885 -- cannot cause overlap. Perhaps we should worry about weird slice
891 Cleft_Lo
:= New_Copy_Tree
(Left_Lo
);
892 Cright_Lo
:= New_Copy_Tree
(Right_Lo
);
894 -- If the types do not match we add an implicit conversion
895 -- here to ensure proper match
897 if Etype
(Left_Lo
) /= Etype
(Right_Lo
) then
899 Unchecked_Convert_To
(Etype
(Left_Lo
), Cright_Lo
);
902 -- Reset the Analyzed flag, because the bounds of the index
903 -- type itself may be universal, and must must be reanalyzed
904 -- to acquire the proper type for the back end.
906 Set_Analyzed
(Cleft_Lo
, False);
907 Set_Analyzed
(Cright_Lo
, False);
911 Left_Opnd
=> Cleft_Lo
,
912 Right_Opnd
=> Cright_Lo
);
915 if Needs_Finalization
(Component_Type
(L_Type
))
916 and then Base_Type
(L_Type
) = Base_Type
(R_Type
)
918 and then not No_Ctrl_Actions
(N
)
921 -- Call TSS procedure for array assignment, passing the
922 -- explicit bounds of right and left hand sides.
925 Proc
: constant Entity_Id
:=
926 TSS
(Base_Type
(L_Type
), TSS_Slice_Assign
);
930 Apply_Dereference
(Larray
);
931 Apply_Dereference
(Rarray
);
932 Actuals
:= New_List
(
933 Duplicate_Subexpr
(Larray
, Name_Req
=> True),
934 Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
935 Duplicate_Subexpr
(Left_Lo
, Name_Req
=> True),
936 Duplicate_Subexpr
(Left_Hi
, Name_Req
=> True),
937 Duplicate_Subexpr
(Right_Lo
, Name_Req
=> True),
938 Duplicate_Subexpr
(Right_Hi
, Name_Req
=> True));
942 Right_Opnd
=> Condition
));
945 Make_Procedure_Call_Statement
(Loc
,
946 Name
=> New_Reference_To
(Proc
, Loc
),
947 Parameter_Associations
=> Actuals
));
952 Make_Implicit_If_Statement
(N
,
953 Condition
=> Condition
,
955 Then_Statements
=> New_List
(
956 Expand_Assign_Array_Loop
957 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
960 Else_Statements
=> New_List
(
961 Expand_Assign_Array_Loop
962 (N
, Larray
, Rarray
, L_Type
, R_Type
, Ndim
,
967 Analyze
(N
, Suppress
=> All_Checks
);
971 when RE_Not_Available
=>
973 end Expand_Assign_Array
;
975 ------------------------------
976 -- Expand_Assign_Array_Loop --
977 ------------------------------
979 -- The following is an example of the loop generated for the case of a
980 -- two-dimensional array:
985 -- for L1b in 1 .. 100 loop
989 -- for L3b in 1 .. 100 loop
990 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
991 -- R4b := Tm1X2'succ(R4b);
994 -- R2b := Tm1X1'succ(R2b);
998 -- Here Rev is False, and Tm1Xn are the subscript types for the right hand
999 -- side. The declarations of R2b and R4b are inserted before the original
1000 -- assignment statement.
1002 function Expand_Assign_Array_Loop
1009 Rev
: Boolean) return Node_Id
1011 Loc
: constant Source_Ptr
:= Sloc
(N
);
1013 Lnn
: array (1 .. Ndim
) of Entity_Id
;
1014 Rnn
: array (1 .. Ndim
) of Entity_Id
;
1015 -- Entities used as subscripts on left and right sides
1017 L_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
1018 R_Index_Type
: array (1 .. Ndim
) of Entity_Id
;
1019 -- Left and right index types
1026 function Build_Step
(J
: Nat
) return Node_Id
;
1027 -- The increment step for the index of the right-hand side is written
1028 -- as an attribute reference (Succ or Pred). This function returns
1029 -- the corresponding node, which is placed at the end of the loop body.
1035 function Build_Step
(J
: Nat
) return Node_Id
is
1047 Make_Assignment_Statement
(Loc
,
1048 Name
=> New_Occurrence_Of
(Rnn
(J
), Loc
),
1050 Make_Attribute_Reference
(Loc
,
1052 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1053 Attribute_Name
=> S_Or_P
,
1054 Expressions
=> New_List
(
1055 New_Occurrence_Of
(Rnn
(J
), Loc
))));
1057 -- Note that on the last iteration of the loop, the index is increased
1058 -- (or decreased) past the corresponding bound. This is consistent with
1059 -- the C semantics of the back-end, where such an off-by-one value on a
1060 -- dead index variable is OK. However, in CodePeer mode this leads to
1061 -- spurious warnings, and thus we place a guard around the attribute
1062 -- reference. For obvious reasons we only do this for CodePeer.
1064 if CodePeer_Mode
then
1066 Make_If_Statement
(Loc
,
1069 Left_Opnd
=> New_Occurrence_Of
(Lnn
(J
), Loc
),
1071 Make_Attribute_Reference
(Loc
,
1072 Prefix
=> New_Occurrence_Of
(L_Index_Type
(J
), Loc
),
1073 Attribute_Name
=> Lim
)),
1074 Then_Statements
=> New_List
(Step
));
1080 -- Start of processing for Expand_Assign_Array_Loop
1084 F_Or_L
:= Name_Last
;
1085 S_Or_P
:= Name_Pred
;
1087 F_Or_L
:= Name_First
;
1088 S_Or_P
:= Name_Succ
;
1091 -- Setup index types and subscript entities
1098 L_Index
:= First_Index
(L_Type
);
1099 R_Index
:= First_Index
(R_Type
);
1101 for J
in 1 .. Ndim
loop
1102 Lnn
(J
) := Make_Temporary
(Loc
, 'L');
1103 Rnn
(J
) := Make_Temporary
(Loc
, 'R');
1105 L_Index_Type
(J
) := Etype
(L_Index
);
1106 R_Index_Type
(J
) := Etype
(R_Index
);
1108 Next_Index
(L_Index
);
1109 Next_Index
(R_Index
);
1113 -- Now construct the assignment statement
1116 ExprL
: constant List_Id
:= New_List
;
1117 ExprR
: constant List_Id
:= New_List
;
1120 for J
in 1 .. Ndim
loop
1121 Append_To
(ExprL
, New_Occurrence_Of
(Lnn
(J
), Loc
));
1122 Append_To
(ExprR
, New_Occurrence_Of
(Rnn
(J
), Loc
));
1126 Make_Assignment_Statement
(Loc
,
1128 Make_Indexed_Component
(Loc
,
1129 Prefix
=> Duplicate_Subexpr
(Larray
, Name_Req
=> True),
1130 Expressions
=> ExprL
),
1132 Make_Indexed_Component
(Loc
,
1133 Prefix
=> Duplicate_Subexpr
(Rarray
, Name_Req
=> True),
1134 Expressions
=> ExprR
));
1136 -- We set assignment OK, since there are some cases, e.g. in object
1137 -- declarations, where we are actually assigning into a constant.
1138 -- If there really is an illegality, it was caught long before now,
1139 -- and was flagged when the original assignment was analyzed.
1141 Set_Assignment_OK
(Name
(Assign
));
1143 -- Propagate the No_Ctrl_Actions flag to individual assignments
1145 Set_No_Ctrl_Actions
(Assign
, No_Ctrl_Actions
(N
));
1148 -- Now construct the loop from the inside out, with the last subscript
1149 -- varying most rapidly. Note that Assign is first the raw assignment
1150 -- statement, and then subsequently the loop that wraps it up.
1152 for J
in reverse 1 .. Ndim
loop
1154 Make_Block_Statement
(Loc
,
1155 Declarations
=> New_List
(
1156 Make_Object_Declaration
(Loc
,
1157 Defining_Identifier
=> Rnn
(J
),
1158 Object_Definition
=>
1159 New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1161 Make_Attribute_Reference
(Loc
,
1162 Prefix
=> New_Occurrence_Of
(R_Index_Type
(J
), Loc
),
1163 Attribute_Name
=> F_Or_L
))),
1165 Handled_Statement_Sequence
=>
1166 Make_Handled_Sequence_Of_Statements
(Loc
,
1167 Statements
=> New_List
(
1168 Make_Implicit_Loop_Statement
(N
,
1170 Make_Iteration_Scheme
(Loc
,
1171 Loop_Parameter_Specification
=>
1172 Make_Loop_Parameter_Specification
(Loc
,
1173 Defining_Identifier
=> Lnn
(J
),
1174 Reverse_Present
=> Rev
,
1175 Discrete_Subtype_Definition
=>
1176 New_Reference_To
(L_Index_Type
(J
), Loc
))),
1178 Statements
=> New_List
(Assign
, Build_Step
(J
))))));
1182 end Expand_Assign_Array_Loop
;
1184 --------------------------
1185 -- Expand_Assign_Record --
1186 --------------------------
1188 procedure Expand_Assign_Record
(N
: Node_Id
) is
1189 Lhs
: constant Node_Id
:= Name
(N
);
1190 Rhs
: Node_Id
:= Expression
(N
);
1191 L_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Lhs
));
1194 -- If change of representation, then extract the real right hand side
1195 -- from the type conversion, and proceed with component-wise assignment,
1196 -- since the two types are not the same as far as the back end is
1199 if Change_Of_Representation
(N
) then
1200 Rhs
:= Expression
(Rhs
);
1202 -- If this may be a case of a large bit aligned component, then proceed
1203 -- with component-wise assignment, to avoid possible clobbering of other
1204 -- components sharing bits in the first or last byte of the component to
1207 elsif Possible_Bit_Aligned_Component
(Lhs
)
1209 Possible_Bit_Aligned_Component
(Rhs
)
1213 -- If we have a tagged type that has a complete record representation
1214 -- clause, we must do we must do component-wise assignments, since child
1215 -- types may have used gaps for their components, and we might be
1216 -- dealing with a view conversion.
1218 elsif Is_Fully_Repped_Tagged_Type
(L_Typ
) then
1221 -- If neither condition met, then nothing special to do, the back end
1222 -- can handle assignment of the entire component as a single entity.
1228 -- At this stage we know that we must do a component wise assignment
1231 Loc
: constant Source_Ptr
:= Sloc
(N
);
1232 R_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Rhs
));
1233 Decl
: constant Node_Id
:= Declaration_Node
(R_Typ
);
1237 function Find_Component
1239 Comp
: Entity_Id
) return Entity_Id
;
1240 -- Find the component with the given name in the underlying record
1241 -- declaration for Typ. We need to use the actual entity because the
1242 -- type may be private and resolution by identifier alone would fail.
1244 function Make_Component_List_Assign
1246 U_U
: Boolean := False) return List_Id
;
1247 -- Returns a sequence of statements to assign the components that
1248 -- are referenced in the given component list. The flag U_U is
1249 -- used to force the usage of the inferred value of the variant
1250 -- part expression as the switch for the generated case statement.
1252 function Make_Field_Assign
1254 U_U
: Boolean := False) return Node_Id
;
1255 -- Given C, the entity for a discriminant or component, build an
1256 -- assignment for the corresponding field values. The flag U_U
1257 -- signals the presence of an Unchecked_Union and forces the usage
1258 -- of the inferred discriminant value of C as the right hand side
1259 -- of the assignment.
1261 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
;
1262 -- Given CI, a component items list, construct series of statements
1263 -- for fieldwise assignment of the corresponding components.
1265 --------------------
1266 -- Find_Component --
1267 --------------------
1269 function Find_Component
1271 Comp
: Entity_Id
) return Entity_Id
1273 Utyp
: constant Entity_Id
:= Underlying_Type
(Typ
);
1277 C
:= First_Entity
(Utyp
);
1278 while Present
(C
) loop
1279 if Chars
(C
) = Chars
(Comp
) then
1286 raise Program_Error
;
1289 --------------------------------
1290 -- Make_Component_List_Assign --
1291 --------------------------------
1293 function Make_Component_List_Assign
1295 U_U
: Boolean := False) return List_Id
1297 CI
: constant List_Id
:= Component_Items
(CL
);
1298 VP
: constant Node_Id
:= Variant_Part
(CL
);
1308 Result
:= Make_Field_Assigns
(CI
);
1310 if Present
(VP
) then
1311 V
:= First_Non_Pragma
(Variants
(VP
));
1313 while Present
(V
) loop
1315 DC
:= First
(Discrete_Choices
(V
));
1316 while Present
(DC
) loop
1317 Append_To
(DCH
, New_Copy_Tree
(DC
));
1322 Make_Case_Statement_Alternative
(Loc
,
1323 Discrete_Choices
=> DCH
,
1325 Make_Component_List_Assign
(Component_List
(V
))));
1326 Next_Non_Pragma
(V
);
1329 -- If we have an Unchecked_Union, use the value of the inferred
1330 -- discriminant of the variant part expression as the switch
1331 -- for the case statement. The case statement may later be
1336 New_Copy
(Get_Discriminant_Value
(
1339 Discriminant_Constraint
(Etype
(Rhs
))));
1342 Make_Selected_Component
(Loc
,
1343 Prefix
=> Duplicate_Subexpr
(Rhs
),
1345 Make_Identifier
(Loc
, Chars
(Name
(VP
))));
1349 Make_Case_Statement
(Loc
,
1351 Alternatives
=> Alts
));
1355 end Make_Component_List_Assign
;
1357 -----------------------
1358 -- Make_Field_Assign --
1359 -----------------------
1361 function Make_Field_Assign
1363 U_U
: Boolean := False) return Node_Id
1369 -- In the case of an Unchecked_Union, use the discriminant
1370 -- constraint value as on the right hand side of the assignment.
1374 New_Copy
(Get_Discriminant_Value
(C
,
1376 Discriminant_Constraint
(Etype
(Rhs
))));
1379 Make_Selected_Component
(Loc
,
1380 Prefix
=> Duplicate_Subexpr
(Rhs
),
1381 Selector_Name
=> New_Occurrence_Of
(C
, Loc
));
1385 Make_Assignment_Statement
(Loc
,
1387 Make_Selected_Component
(Loc
,
1388 Prefix
=> Duplicate_Subexpr
(Lhs
),
1390 New_Occurrence_Of
(Find_Component
(L_Typ
, C
), Loc
)),
1391 Expression
=> Expr
);
1393 -- Set Assignment_OK, so discriminants can be assigned
1395 Set_Assignment_OK
(Name
(A
), True);
1397 if Componentwise_Assignment
(N
)
1398 and then Nkind
(Name
(A
)) = N_Selected_Component
1399 and then Chars
(Selector_Name
(Name
(A
))) = Name_uParent
1401 Set_Componentwise_Assignment
(A
);
1405 end Make_Field_Assign
;
1407 ------------------------
1408 -- Make_Field_Assigns --
1409 ------------------------
1411 function Make_Field_Assigns
(CI
: List_Id
) return List_Id
is
1419 while Present
(Item
) loop
1421 -- Look for components, but exclude _tag field assignment if
1422 -- the special Componentwise_Assignment flag is set.
1424 if Nkind
(Item
) = N_Component_Declaration
1425 and then not (Is_Tag
(Defining_Identifier
(Item
))
1426 and then Componentwise_Assignment
(N
))
1429 (Result
, Make_Field_Assign
(Defining_Identifier
(Item
)));
1436 end Make_Field_Assigns
;
1438 -- Start of processing for Expand_Assign_Record
1441 -- Note that we use the base types for this processing. This results
1442 -- in some extra work in the constrained case, but the change of
1443 -- representation case is so unusual that it is not worth the effort.
1445 -- First copy the discriminants. This is done unconditionally. It
1446 -- is required in the unconstrained left side case, and also in the
1447 -- case where this assignment was constructed during the expansion
1448 -- of a type conversion (since initialization of discriminants is
1449 -- suppressed in this case). It is unnecessary but harmless in
1452 if Has_Discriminants
(L_Typ
) then
1453 F
:= First_Discriminant
(R_Typ
);
1454 while Present
(F
) loop
1456 -- If we are expanding the initialization of a derived record
1457 -- that constrains or renames discriminants of the parent, we
1458 -- must use the corresponding discriminant in the parent.
1465 and then Present
(Corresponding_Discriminant
(F
))
1467 CF
:= Corresponding_Discriminant
(F
);
1472 if Is_Unchecked_Union
(Base_Type
(R_Typ
)) then
1474 -- Within an initialization procedure this is the
1475 -- assignment to an unchecked union component, in which
1476 -- case there is no discriminant to initialize.
1478 if Inside_Init_Proc
then
1482 -- The assignment is part of a conversion from a
1483 -- derived unchecked union type with an inferable
1484 -- discriminant, to a parent type.
1486 Insert_Action
(N
, Make_Field_Assign
(CF
, True));
1490 Insert_Action
(N
, Make_Field_Assign
(CF
));
1493 Next_Discriminant
(F
);
1498 -- We know the underlying type is a record, but its current view
1499 -- may be private. We must retrieve the usable record declaration.
1501 if Nkind_In
(Decl
, N_Private_Type_Declaration
,
1502 N_Private_Extension_Declaration
)
1503 and then Present
(Full_View
(R_Typ
))
1505 RDef
:= Type_Definition
(Declaration_Node
(Full_View
(R_Typ
)));
1507 RDef
:= Type_Definition
(Decl
);
1510 if Nkind
(RDef
) = N_Derived_Type_Definition
then
1511 RDef
:= Record_Extension_Part
(RDef
);
1514 if Nkind
(RDef
) = N_Record_Definition
1515 and then Present
(Component_List
(RDef
))
1517 if Is_Unchecked_Union
(R_Typ
) then
1519 Make_Component_List_Assign
(Component_List
(RDef
), True));
1522 (N
, Make_Component_List_Assign
(Component_List
(RDef
)));
1525 Rewrite
(N
, Make_Null_Statement
(Loc
));
1528 end Expand_Assign_Record
;
1530 ----------------------------------
1531 -- Expand_Loop_Entry_Attributes --
1532 ----------------------------------
1534 procedure Expand_Loop_Entry_Attributes
(N
: Node_Id
) is
1535 procedure Build_Conditional_Block
1539 If_Stmt
: out Node_Id
;
1540 Blk_Stmt
: out Node_Id
);
1541 -- Create a block Blk_Stmt with an empty declarative list and a single
1542 -- statement Stmt. The block is encased in an if statement If_Stmt with
1543 -- condition Cond. If_Stmt is Empty when there is no condition provided.
1545 function Is_Array_Iteration
(N
: Node_Id
) return Boolean;
1546 -- Determine whether loop statement N denotes an Ada 2012 iteration over
1549 -----------------------------
1550 -- Build_Conditional_Block --
1551 -----------------------------
1553 procedure Build_Conditional_Block
1557 If_Stmt
: out Node_Id
;
1558 Blk_Stmt
: out Node_Id
)
1562 Make_Block_Statement
(Loc
,
1563 Declarations
=> New_List
,
1564 Handled_Statement_Sequence
=>
1565 Make_Handled_Sequence_Of_Statements
(Loc
,
1566 Statements
=> New_List
(Stmt
)));
1568 if Present
(Cond
) then
1570 Make_If_Statement
(Loc
,
1572 Then_Statements
=> New_List
(Blk_Stmt
));
1576 end Build_Conditional_Block
;
1578 ------------------------
1579 -- Is_Array_Iteration --
1580 ------------------------
1582 function Is_Array_Iteration
(N
: Node_Id
) return Boolean is
1583 Stmt
: constant Node_Id
:= Original_Node
(N
);
1587 if Nkind
(Stmt
) = N_Loop_Statement
1588 and then Present
(Iteration_Scheme
(Stmt
))
1589 and then Present
(Iterator_Specification
(Iteration_Scheme
(Stmt
)))
1591 Iter
:= Iterator_Specification
(Iteration_Scheme
(Stmt
));
1595 and then Is_Array_Type
(Etype
(Name
(Iter
)));
1599 end Is_Array_Iteration
;
1603 Loc
: constant Source_Ptr
:= Sloc
(N
);
1604 Loop_Id
: constant Entity_Id
:= Identifier
(N
);
1605 Scheme
: constant Node_Id
:= Iteration_Scheme
(N
);
1613 -- Start of processing for Expand_Loop_Entry_Attributes
1616 -- The loop will never execute after it has been expanded, no point in
1619 if Is_Null_Loop
(N
) then
1622 -- A loop without an identifier cannot be referenced in 'Loop_Entry
1624 elsif No
(Loop_Id
) then
1627 -- The loop is not subject to 'Loop_Entry
1629 elsif No
(Loop_Entry_Attributes
(Entity
(Loop_Id
))) then
1632 -- Step 1: Loop transformations
1634 -- While loops are transformed into:
1636 -- if <Condition> then
1638 -- Temp1 : constant <type of Pref1> := <Pref1>;
1640 -- TempN : constant <type of PrefN> := <PrefN>;
1643 -- <original source statements with attribute rewrites>
1644 -- exit when not <Condition>;
1649 -- Note that loops over iterators and containers are already converted
1650 -- into while loops.
1652 elsif Present
(Condition
(Scheme
)) then
1654 Cond
: constant Node_Id
:= Condition
(Scheme
);
1657 -- Transform the original while loop into an infinite loop where
1658 -- the last statement checks the negated condition. This placement
1659 -- ensures that the condition will not be evaluated twice on the
1663 -- exit when not <Cond>:
1665 Append_To
(Statements
(N
),
1666 Make_Exit_Statement
(Loc
,
1667 Condition
=> Make_Op_Not
(Loc
, New_Copy_Tree
(Cond
))));
1669 Build_Conditional_Block
(Loc
,
1670 Cond
=> Relocate_Node
(Cond
),
1671 Stmt
=> Relocate_Node
(N
),
1676 -- Ada 2012 iteration over an array is transformed into:
1678 -- if <Array_Nam>'Length (1) > 0
1679 -- and then <Array_Nam>'Length (N) > 0
1682 -- Temp1 : constant <type of Pref1> := <Pref1>;
1684 -- TempN : constant <type of PrefN> := <PrefN>;
1686 -- for X in ... loop -- multiple loops depending on dims
1687 -- <original source statements with attribute rewrites>
1692 elsif Is_Array_Iteration
(N
) then
1694 Array_Nam
: constant Entity_Id
:=
1695 Entity
(Name
(Iterator_Specification
1696 (Iteration_Scheme
(Original_Node
(N
)))));
1697 Num_Dims
: constant Pos
:=
1698 Number_Dimensions
(Etype
(Array_Nam
));
1699 Cond
: Node_Id
:= Empty
;
1704 -- Generate a check which determines whether all dimensions of
1705 -- the array are non-null.
1707 for Dim
in 1 .. Num_Dims
loop
1711 Make_Attribute_Reference
(Loc
,
1712 Prefix
=> New_Reference_To
(Array_Nam
, Loc
),
1713 Attribute_Name
=> Name_Length
,
1714 Expressions
=> New_List
(
1715 Make_Integer_Literal
(Loc
, Dim
))),
1717 Make_Integer_Literal
(Loc
, 0));
1725 Right_Opnd
=> Check
);
1729 Top_Loop
:= Relocate_Node
(N
);
1730 Set_Analyzed
(Top_Loop
);
1732 Build_Conditional_Block
(Loc
,
1739 -- For loops are transformed into:
1741 -- if <Low> <= <High> then
1743 -- Temp1 : constant <type of Pref1> := <Pref1>;
1745 -- TempN : constant <type of PrefN> := <PrefN>;
1747 -- for <Def_Id> in <Low> .. <High> loop
1748 -- <original source statements with attribute rewrites>
1753 elsif Present
(Loop_Parameter_Specification
(Scheme
)) then
1755 Loop_Spec
: constant Node_Id
:=
1756 Loop_Parameter_Specification
(Scheme
);
1757 Subt_Def
: constant Node_Id
:=
1758 Discrete_Subtype_Definition
(Loop_Spec
);
1762 -- At this point in the expansion all discrete subtype definitions
1763 -- should be transformed into ranges.
1765 pragma Assert
(Nkind
(Subt_Def
) = N_Range
);
1772 Left_Opnd
=> New_Copy_Tree
(Low_Bound
(Subt_Def
)),
1773 Right_Opnd
=> New_Copy_Tree
(High_Bound
(Subt_Def
)));
1775 Build_Conditional_Block
(Loc
,
1777 Stmt
=> Relocate_Node
(N
),
1782 -- Infinite loops are transformed into:
1785 -- Temp1 : constant <type of Pref1> := <Pref1>;
1787 -- TempN : constant <type of PrefN> := <PrefN>;
1790 -- <original source statements with attribute rewrites>
1795 Build_Conditional_Block
(Loc
,
1797 Stmt
=> Relocate_Node
(N
),
1804 -- Step 2: Loop_Entry attribute transformations
1806 -- At this point the various loops have been augmented to contain a
1807 -- block. Populate the declarative list of the block with constants
1808 -- which store the value of their relative prefixes at the point of
1809 -- entry in the loop.
1811 LE_Elmt
:= First_Elmt
(Loop_Entry_Attributes
(Entity
(Loop_Id
)));
1812 while Present
(LE_Elmt
) loop
1813 LE
:= Node
(LE_Elmt
);
1814 Typ
:= Etype
(Prefix
(LE
));
1816 -- Declare a constant to capture the value of the previx of each
1817 -- Loop_Entry attribute.
1820 -- Temp : constant <type of Pref> := <Pref>;
1822 Temp
:= Make_Temporary
(Loc
, 'P');
1824 Append_To
(Declarations
(Blk
),
1825 Make_Object_Declaration
(Loc
,
1826 Defining_Identifier
=> Temp
,
1827 Constant_Present
=> True,
1828 Object_Definition
=> New_Reference_To
(Typ
, Loc
),
1829 Expression
=> Relocate_Node
(Prefix
(LE
))));
1831 -- Replace the original attribute with a reference to the constant
1833 Rewrite
(LE
, New_Reference_To
(Temp
, Loc
));
1834 Set_Etype
(LE
, Typ
);
1836 Next_Elmt
(LE_Elmt
);
1839 -- Destroy the list of Loop_Entry attributes to prevent the infinite
1840 -- expansion when analyzing and expanding the newly generated loops.
1842 Set_Loop_Entry_Attributes
(Entity
(Loop_Id
), No_Elist
);
1844 Rewrite
(N
, Result
);
1846 end Expand_Loop_Entry_Attributes
;
1848 -----------------------------------
1849 -- Expand_N_Assignment_Statement --
1850 -----------------------------------
1852 -- This procedure implements various cases where an assignment statement
1853 -- cannot just be passed on to the back end in untransformed state.
1855 procedure Expand_N_Assignment_Statement
(N
: Node_Id
) is
1856 Loc
: constant Source_Ptr
:= Sloc
(N
);
1857 Crep
: constant Boolean := Change_Of_Representation
(N
);
1858 Lhs
: constant Node_Id
:= Name
(N
);
1859 Rhs
: constant Node_Id
:= Expression
(N
);
1860 Typ
: constant Entity_Id
:= Underlying_Type
(Etype
(Lhs
));
1864 -- Special case to check right away, if the Componentwise_Assignment
1865 -- flag is set, this is a reanalysis from the expansion of the primitive
1866 -- assignment procedure for a tagged type, and all we need to do is to
1867 -- expand to assignment of components, because otherwise, we would get
1868 -- infinite recursion (since this looks like a tagged assignment which
1869 -- would normally try to *call* the primitive assignment procedure).
1871 if Componentwise_Assignment
(N
) then
1872 Expand_Assign_Record
(N
);
1876 -- Defend against invalid subscripts on left side if we are in standard
1877 -- validity checking mode. No need to do this if we are checking all
1880 -- Note that we do this right away, because there are some early return
1881 -- paths in this procedure, and this is required on all paths.
1883 if Validity_Checks_On
1884 and then Validity_Check_Default
1885 and then not Validity_Check_Subscripts
1887 Check_Valid_Lvalue_Subscripts
(Lhs
);
1890 -- Ada 2005 (AI-327): Handle assignment to priority of protected object
1892 -- Rewrite an assignment to X'Priority into a run-time call
1894 -- For example: X'Priority := New_Prio_Expr;
1895 -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr);
1897 -- Note that although X'Priority is notionally an object, it is quite
1898 -- deliberately not defined as an aliased object in the RM. This means
1899 -- that it works fine to rewrite it as a call, without having to worry
1900 -- about complications that would other arise from X'Priority'Access,
1901 -- which is illegal, because of the lack of aliasing.
1903 if Ada_Version
>= Ada_2005
then
1906 Conctyp
: Entity_Id
;
1909 RT_Subprg_Name
: Node_Id
;
1912 -- Handle chains of renamings
1915 while Nkind
(Ent
) in N_Has_Entity
1916 and then Present
(Entity
(Ent
))
1917 and then Present
(Renamed_Object
(Entity
(Ent
)))
1919 Ent
:= Renamed_Object
(Entity
(Ent
));
1922 -- The attribute Priority applied to protected objects has been
1923 -- previously expanded into a call to the Get_Ceiling run-time
1926 if Nkind
(Ent
) = N_Function_Call
1927 and then (Entity
(Name
(Ent
)) = RTE
(RE_Get_Ceiling
)
1929 Entity
(Name
(Ent
)) = RTE
(RO_PE_Get_Ceiling
))
1931 -- Look for the enclosing concurrent type
1933 Conctyp
:= Current_Scope
;
1934 while not Is_Concurrent_Type
(Conctyp
) loop
1935 Conctyp
:= Scope
(Conctyp
);
1938 pragma Assert
(Is_Protected_Type
(Conctyp
));
1940 -- Generate the first actual of the call
1942 Subprg
:= Current_Scope
;
1943 while not Present
(Protected_Body_Subprogram
(Subprg
)) loop
1944 Subprg
:= Scope
(Subprg
);
1947 -- Select the appropriate run-time call
1949 if Number_Entries
(Conctyp
) = 0 then
1951 New_Reference_To
(RTE
(RE_Set_Ceiling
), Loc
);
1954 New_Reference_To
(RTE
(RO_PE_Set_Ceiling
), Loc
);
1958 Make_Procedure_Call_Statement
(Loc
,
1959 Name
=> RT_Subprg_Name
,
1960 Parameter_Associations
=> New_List
(
1961 New_Copy_Tree
(First
(Parameter_Associations
(Ent
))),
1962 Relocate_Node
(Expression
(N
))));
1971 -- Deal with assignment checks unless suppressed
1973 if not Suppress_Assignment_Checks
(N
) then
1975 -- First deal with generation of range check if required
1977 if Do_Range_Check
(Rhs
) then
1978 Set_Do_Range_Check
(Rhs
, False);
1979 Generate_Range_Check
(Rhs
, Typ
, CE_Range_Check_Failed
);
1982 -- Then generate predicate check if required
1984 Apply_Predicate_Check
(Rhs
, Typ
);
1987 -- Check for a special case where a high level transformation is
1988 -- required. If we have either of:
1993 -- where P is a reference to a bit packed array, then we have to unwind
1994 -- the assignment. The exact meaning of being a reference to a bit
1995 -- packed array is as follows:
1997 -- An indexed component whose prefix is a bit packed array is a
1998 -- reference to a bit packed array.
2000 -- An indexed component or selected component whose prefix is a
2001 -- reference to a bit packed array is itself a reference ot a
2002 -- bit packed array.
2004 -- The required transformation is
2006 -- Tnn : prefix_type := P;
2007 -- Tnn.field := rhs;
2012 -- Tnn : prefix_type := P;
2013 -- Tnn (subscr) := rhs;
2016 -- Since P is going to be evaluated more than once, any subscripts
2017 -- in P must have their evaluation forced.
2019 if Nkind_In
(Lhs
, N_Indexed_Component
, N_Selected_Component
)
2020 and then Is_Ref_To_Bit_Packed_Array
(Prefix
(Lhs
))
2023 BPAR_Expr
: constant Node_Id
:= Relocate_Node
(Prefix
(Lhs
));
2024 BPAR_Typ
: constant Entity_Id
:= Etype
(BPAR_Expr
);
2025 Tnn
: constant Entity_Id
:=
2026 Make_Temporary
(Loc
, 'T', BPAR_Expr
);
2029 -- Insert the post assignment first, because we want to copy the
2030 -- BPAR_Expr tree before it gets analyzed in the context of the
2031 -- pre assignment. Note that we do not analyze the post assignment
2032 -- yet (we cannot till we have completed the analysis of the pre
2033 -- assignment). As usual, the analysis of this post assignment
2034 -- will happen on its own when we "run into" it after finishing
2035 -- the current assignment.
2038 Make_Assignment_Statement
(Loc
,
2039 Name
=> New_Copy_Tree
(BPAR_Expr
),
2040 Expression
=> New_Occurrence_Of
(Tnn
, Loc
)));
2042 -- At this stage BPAR_Expr is a reference to a bit packed array
2043 -- where the reference was not expanded in the original tree,
2044 -- since it was on the left side of an assignment. But in the
2045 -- pre-assignment statement (the object definition), BPAR_Expr
2046 -- will end up on the right hand side, and must be reexpanded. To
2047 -- achieve this, we reset the analyzed flag of all selected and
2048 -- indexed components down to the actual indexed component for
2049 -- the packed array.
2053 Set_Analyzed
(Exp
, False);
2056 (Exp
, N_Selected_Component
, N_Indexed_Component
)
2058 Exp
:= Prefix
(Exp
);
2064 -- Now we can insert and analyze the pre-assignment
2066 -- If the right-hand side requires a transient scope, it has
2067 -- already been placed on the stack. However, the declaration is
2068 -- inserted in the tree outside of this scope, and must reflect
2069 -- the proper scope for its variable. This awkward bit is forced
2070 -- by the stricter scope discipline imposed by GCC 2.97.
2073 Uses_Transient_Scope
: constant Boolean :=
2075 and then N
= Node_To_Be_Wrapped
;
2078 if Uses_Transient_Scope
then
2079 Push_Scope
(Scope
(Current_Scope
));
2082 Insert_Before_And_Analyze
(N
,
2083 Make_Object_Declaration
(Loc
,
2084 Defining_Identifier
=> Tnn
,
2085 Object_Definition
=> New_Occurrence_Of
(BPAR_Typ
, Loc
),
2086 Expression
=> BPAR_Expr
));
2088 if Uses_Transient_Scope
then
2093 -- Now fix up the original assignment and continue processing
2095 Rewrite
(Prefix
(Lhs
),
2096 New_Occurrence_Of
(Tnn
, Loc
));
2098 -- We do not need to reanalyze that assignment, and we do not need
2099 -- to worry about references to the temporary, but we do need to
2100 -- make sure that the temporary is not marked as a true constant
2101 -- since we now have a generated assignment to it!
2103 Set_Is_True_Constant
(Tnn
, False);
2107 -- When we have the appropriate type of aggregate in the expression (it
2108 -- has been determined during analysis of the aggregate by setting the
2109 -- delay flag), let's perform in place assignment and thus avoid
2110 -- creating a temporary.
2112 if Is_Delayed_Aggregate
(Rhs
) then
2113 Convert_Aggr_In_Assignment
(N
);
2114 Rewrite
(N
, Make_Null_Statement
(Loc
));
2119 -- Apply discriminant check if required. If Lhs is an access type to a
2120 -- designated type with discriminants, we must always check.
2122 if Has_Discriminants
(Etype
(Lhs
)) then
2124 -- Skip discriminant check if change of representation. Will be
2125 -- done when the change of representation is expanded out.
2128 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
), Lhs
);
2131 -- If the type is private without discriminants, and the full type
2132 -- has discriminants (necessarily with defaults) a check may still be
2133 -- necessary if the Lhs is aliased. The private discriminants must be
2134 -- visible to build the discriminant constraints.
2136 -- Only an explicit dereference that comes from source indicates
2137 -- aliasing. Access to formals of protected operations and entries
2138 -- create dereferences but are not semantic aliasings.
2140 elsif Is_Private_Type
(Etype
(Lhs
))
2141 and then Has_Discriminants
(Typ
)
2142 and then Nkind
(Lhs
) = N_Explicit_Dereference
2143 and then Comes_From_Source
(Lhs
)
2146 Lt
: constant Entity_Id
:= Etype
(Lhs
);
2147 Ubt
: Entity_Id
:= Base_Type
(Typ
);
2150 -- In the case of an expander-generated record subtype whose base
2151 -- type still appears private, Typ will have been set to that
2152 -- private type rather than the underlying record type (because
2153 -- Underlying type will have returned the record subtype), so it's
2154 -- necessary to apply Underlying_Type again to the base type to
2155 -- get the record type we need for the discriminant check. Such
2156 -- subtypes can be created for assignments in certain cases, such
2157 -- as within an instantiation passed this kind of private type.
2158 -- It would be good to avoid this special test, but making changes
2159 -- to prevent this odd form of record subtype seems difficult. ???
2161 if Is_Private_Type
(Ubt
) then
2162 Ubt
:= Underlying_Type
(Ubt
);
2165 Set_Etype
(Lhs
, Ubt
);
2166 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Ubt
), Rhs
));
2167 Apply_Discriminant_Check
(Rhs
, Ubt
, Lhs
);
2168 Set_Etype
(Lhs
, Lt
);
2171 -- If the Lhs has a private type with unknown discriminants, it
2172 -- may have a full view with discriminants, but those are nameable
2173 -- only in the underlying type, so convert the Rhs to it before
2174 -- potential checking.
2176 elsif Has_Unknown_Discriminants
(Base_Type
(Etype
(Lhs
)))
2177 and then Has_Discriminants
(Typ
)
2179 Rewrite
(Rhs
, OK_Convert_To
(Base_Type
(Typ
), Rhs
));
2180 Apply_Discriminant_Check
(Rhs
, Typ
, Lhs
);
2182 -- In the access type case, we need the same discriminant check, and
2183 -- also range checks if we have an access to constrained array.
2185 elsif Is_Access_Type
(Etype
(Lhs
))
2186 and then Is_Constrained
(Designated_Type
(Etype
(Lhs
)))
2188 if Has_Discriminants
(Designated_Type
(Etype
(Lhs
))) then
2190 -- Skip discriminant check if change of representation. Will be
2191 -- done when the change of representation is expanded out.
2194 Apply_Discriminant_Check
(Rhs
, Etype
(Lhs
));
2197 elsif Is_Array_Type
(Designated_Type
(Etype
(Lhs
))) then
2198 Apply_Range_Check
(Rhs
, Etype
(Lhs
));
2200 if Is_Constrained
(Etype
(Lhs
)) then
2201 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
2204 if Nkind
(Rhs
) = N_Allocator
then
2206 Target_Typ
: constant Entity_Id
:= Etype
(Expression
(Rhs
));
2207 C_Es
: Check_Result
;
2214 Etype
(Designated_Type
(Etype
(Lhs
))));
2226 -- Apply range check for access type case
2228 elsif Is_Access_Type
(Etype
(Lhs
))
2229 and then Nkind
(Rhs
) = N_Allocator
2230 and then Nkind
(Expression
(Rhs
)) = N_Qualified_Expression
2232 Analyze_And_Resolve
(Expression
(Rhs
));
2234 (Expression
(Rhs
), Designated_Type
(Etype
(Lhs
)));
2237 -- Ada 2005 (AI-231): Generate the run-time check
2239 if Is_Access_Type
(Typ
)
2240 and then Can_Never_Be_Null
(Etype
(Lhs
))
2241 and then not Can_Never_Be_Null
(Etype
(Rhs
))
2243 Apply_Constraint_Check
(Rhs
, Etype
(Lhs
));
2246 -- Ada 2012 (AI05-148): Update current accessibility level if Rhs is a
2247 -- stand-alone obj of an anonymous access type.
2249 if Is_Access_Type
(Typ
)
2250 and then Is_Entity_Name
(Lhs
)
2251 and then Present
(Effective_Extra_Accessibility
(Entity
(Lhs
))) then
2253 function Lhs_Entity
return Entity_Id
;
2254 -- Look through renames to find the underlying entity.
2255 -- For assignment to a rename, we don't care about the
2256 -- Enclosing_Dynamic_Scope of the rename declaration.
2262 function Lhs_Entity
return Entity_Id
is
2263 Result
: Entity_Id
:= Entity
(Lhs
);
2266 while Present
(Renamed_Object
(Result
)) loop
2268 -- Renamed_Object must return an Entity_Name here
2269 -- because of preceding "Present (E_E_A (...))" test.
2271 Result
:= Entity
(Renamed_Object
(Result
));
2277 -- Local Declarations
2279 Access_Check
: constant Node_Id
:=
2280 Make_Raise_Program_Error
(Loc
,
2284 Dynamic_Accessibility_Level
(Rhs
),
2286 Make_Integer_Literal
(Loc
,
2289 (Enclosing_Dynamic_Scope
2291 Reason
=> PE_Accessibility_Check_Failed
);
2293 Access_Level_Update
: constant Node_Id
:=
2294 Make_Assignment_Statement
(Loc
,
2297 (Effective_Extra_Accessibility
2298 (Entity
(Lhs
)), Loc
),
2300 Dynamic_Accessibility_Level
(Rhs
));
2303 if not Accessibility_Checks_Suppressed
(Entity
(Lhs
)) then
2304 Insert_Action
(N
, Access_Check
);
2307 Insert_Action
(N
, Access_Level_Update
);
2311 -- Case of assignment to a bit packed array element. If there is a
2312 -- change of representation this must be expanded into components,
2313 -- otherwise this is a bit-field assignment.
2315 if Nkind
(Lhs
) = N_Indexed_Component
2316 and then Is_Bit_Packed_Array
(Etype
(Prefix
(Lhs
)))
2318 -- Normal case, no change of representation
2321 Expand_Bit_Packed_Element_Set
(N
);
2324 -- Change of representation case
2327 -- Generate the following, to force component-by-component
2328 -- assignments in an efficient way. Otherwise each component
2329 -- will require a temporary and two bit-field manipulations.
2336 Tnn
: constant Entity_Id
:= Make_Temporary
(Loc
, 'T');
2342 Make_Object_Declaration
(Loc
,
2343 Defining_Identifier
=> Tnn
,
2344 Object_Definition
=>
2345 New_Occurrence_Of
(Etype
(Lhs
), Loc
)),
2346 Make_Assignment_Statement
(Loc
,
2347 Name
=> New_Occurrence_Of
(Tnn
, Loc
),
2348 Expression
=> Relocate_Node
(Rhs
)),
2349 Make_Assignment_Statement
(Loc
,
2350 Name
=> Relocate_Node
(Lhs
),
2351 Expression
=> New_Occurrence_Of
(Tnn
, Loc
)));
2353 Insert_Actions
(N
, Stats
);
2354 Rewrite
(N
, Make_Null_Statement
(Loc
));
2359 -- Build-in-place function call case. Note that we're not yet doing
2360 -- build-in-place for user-written assignment statements (the assignment
2361 -- here came from an aggregate.)
2363 elsif Ada_Version
>= Ada_2005
2364 and then Is_Build_In_Place_Function_Call
(Rhs
)
2366 Make_Build_In_Place_Call_In_Assignment
(N
, Rhs
);
2368 elsif Is_Tagged_Type
(Typ
) and then Is_Value_Type
(Etype
(Lhs
)) then
2370 -- Nothing to do for valuetypes
2371 -- ??? Set_Scope_Is_Transient (False);
2375 elsif Is_Tagged_Type
(Typ
)
2376 or else (Needs_Finalization
(Typ
) and then not Is_Array_Type
(Typ
))
2378 Tagged_Case
: declare
2379 L
: List_Id
:= No_List
;
2380 Expand_Ctrl_Actions
: constant Boolean := not No_Ctrl_Actions
(N
);
2383 -- In the controlled case, we ensure that function calls are
2384 -- evaluated before finalizing the target. In all cases, it makes
2385 -- the expansion easier if the side-effects are removed first.
2387 Remove_Side_Effects
(Lhs
);
2388 Remove_Side_Effects
(Rhs
);
2390 -- Avoid recursion in the mechanism
2394 -- If dispatching assignment, we need to dispatch to _assign
2396 if Is_Class_Wide_Type
(Typ
)
2398 -- If the type is tagged, we may as well use the predefined
2399 -- primitive assignment. This avoids inlining a lot of code
2400 -- and in the class-wide case, the assignment is replaced
2401 -- by a dispatching call to _assign. It is suppressed in the
2402 -- case of assignments created by the expander that correspond
2403 -- to initializations, where we do want to copy the tag
2404 -- (Expand_Ctrl_Actions flag is set True in this case). It is
2405 -- also suppressed if restriction No_Dispatching_Calls is in
2406 -- force because in that case predefined primitives are not
2409 or else (Is_Tagged_Type
(Typ
)
2410 and then not Is_Value_Type
(Etype
(Lhs
))
2411 and then Chars
(Current_Scope
) /= Name_uAssign
2412 and then Expand_Ctrl_Actions
2414 not Restriction_Active
(No_Dispatching_Calls
))
2416 if Is_Limited_Type
(Typ
) then
2418 -- This can happen in an instance when the formal is an
2419 -- extension of a limited interface, and the actual is
2420 -- limited. This is an error according to AI05-0087, but
2421 -- is not caught at the point of instantiation in earlier
2424 -- This is wrong, error messages cannot be issued during
2425 -- expansion, since they would be missed in -gnatc mode ???
2427 Error_Msg_N
("assignment not available on limited type", N
);
2431 -- Fetch the primitive op _assign and proper type to call it.
2432 -- Because of possible conflicts between private and full view,
2433 -- fetch the proper type directly from the operation profile.
2436 Op
: constant Entity_Id
:=
2437 Find_Prim_Op
(Typ
, Name_uAssign
);
2438 F_Typ
: Entity_Id
:= Etype
(First_Formal
(Op
));
2441 -- If the assignment is dispatching, make sure to use the
2444 if Is_Class_Wide_Type
(Typ
) then
2445 F_Typ
:= Class_Wide_Type
(F_Typ
);
2450 -- In case of assignment to a class-wide tagged type, before
2451 -- the assignment we generate run-time check to ensure that
2452 -- the tags of source and target match.
2454 if Is_Class_Wide_Type
(Typ
)
2455 and then Is_Tagged_Type
(Typ
)
2456 and then Is_Tagged_Type
(Underlying_Type
(Etype
(Rhs
)))
2459 Make_Raise_Constraint_Error
(Loc
,
2463 Make_Selected_Component
(Loc
,
2464 Prefix
=> Duplicate_Subexpr
(Lhs
),
2466 Make_Identifier
(Loc
, Name_uTag
)),
2468 Make_Selected_Component
(Loc
,
2469 Prefix
=> Duplicate_Subexpr
(Rhs
),
2471 Make_Identifier
(Loc
, Name_uTag
))),
2472 Reason
=> CE_Tag_Check_Failed
));
2476 Left_N
: Node_Id
:= Duplicate_Subexpr
(Lhs
);
2477 Right_N
: Node_Id
:= Duplicate_Subexpr
(Rhs
);
2480 -- In order to dispatch the call to _assign the type of
2481 -- the actuals must match. Add conversion (if required).
2483 if Etype
(Lhs
) /= F_Typ
then
2484 Left_N
:= Unchecked_Convert_To
(F_Typ
, Left_N
);
2487 if Etype
(Rhs
) /= F_Typ
then
2488 Right_N
:= Unchecked_Convert_To
(F_Typ
, Right_N
);
2492 Make_Procedure_Call_Statement
(Loc
,
2493 Name
=> New_Reference_To
(Op
, Loc
),
2494 Parameter_Associations
=> New_List
(
2496 Node2
=> Right_N
)));
2501 L
:= Make_Tag_Ctrl_Assignment
(N
);
2503 -- We can't afford to have destructive Finalization Actions in
2504 -- the Self assignment case, so if the target and the source
2505 -- are not obviously different, code is generated to avoid the
2506 -- self assignment case:
2508 -- if lhs'address /= rhs'address then
2509 -- <code for controlled and/or tagged assignment>
2512 -- Skip this if Restriction (No_Finalization) is active
2514 if not Statically_Different
(Lhs
, Rhs
)
2515 and then Expand_Ctrl_Actions
2516 and then not Restriction_Active
(No_Finalization
)
2519 Make_Implicit_If_Statement
(N
,
2523 Make_Attribute_Reference
(Loc
,
2524 Prefix
=> Duplicate_Subexpr
(Lhs
),
2525 Attribute_Name
=> Name_Address
),
2528 Make_Attribute_Reference
(Loc
,
2529 Prefix
=> Duplicate_Subexpr
(Rhs
),
2530 Attribute_Name
=> Name_Address
)),
2532 Then_Statements
=> L
));
2535 -- We need to set up an exception handler for implementing
2536 -- 7.6.1(18). The remaining adjustments are tackled by the
2537 -- implementation of adjust for record_controllers (see
2540 -- This is skipped if we have no finalization
2542 if Expand_Ctrl_Actions
2543 and then not Restriction_Active
(No_Finalization
)
2546 Make_Block_Statement
(Loc
,
2547 Handled_Statement_Sequence
=>
2548 Make_Handled_Sequence_Of_Statements
(Loc
,
2550 Exception_Handlers
=> New_List
(
2551 Make_Handler_For_Ctrl_Operation
(Loc
)))));
2556 Make_Block_Statement
(Loc
,
2557 Handled_Statement_Sequence
=>
2558 Make_Handled_Sequence_Of_Statements
(Loc
, Statements
=> L
)));
2560 -- If no restrictions on aborts, protect the whole assignment
2561 -- for controlled objects as per 9.8(11).
2563 if Needs_Finalization
(Typ
)
2564 and then Expand_Ctrl_Actions
2565 and then Abort_Allowed
2568 Blk
: constant Entity_Id
:=
2570 (E_Block
, Current_Scope
, Sloc
(N
), 'B');
2573 Set_Scope
(Blk
, Current_Scope
);
2574 Set_Etype
(Blk
, Standard_Void_Type
);
2575 Set_Identifier
(N
, New_Occurrence_Of
(Blk
, Sloc
(N
)));
2577 Prepend_To
(L
, Build_Runtime_Call
(Loc
, RE_Abort_Defer
));
2578 Set_At_End_Proc
(Handled_Statement_Sequence
(N
),
2579 New_Occurrence_Of
(RTE
(RE_Abort_Undefer_Direct
), Loc
));
2580 Expand_At_End_Handler
2581 (Handled_Statement_Sequence
(N
), Blk
);
2585 -- N has been rewritten to a block statement for which it is
2586 -- known by construction that no checks are necessary: analyze
2587 -- it with all checks suppressed.
2589 Analyze
(N
, Suppress
=> All_Checks
);
2595 elsif Is_Array_Type
(Typ
) then
2597 Actual_Rhs
: Node_Id
:= Rhs
;
2600 while Nkind_In
(Actual_Rhs
, N_Type_Conversion
,
2601 N_Qualified_Expression
)
2603 Actual_Rhs
:= Expression
(Actual_Rhs
);
2606 Expand_Assign_Array
(N
, Actual_Rhs
);
2612 elsif Is_Record_Type
(Typ
) then
2613 Expand_Assign_Record
(N
);
2616 -- Scalar types. This is where we perform the processing related to the
2617 -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid
2620 elsif Is_Scalar_Type
(Typ
) then
2622 -- Case where right side is known valid
2624 if Expr_Known_Valid
(Rhs
) then
2626 -- Here the right side is valid, so it is fine. The case to deal
2627 -- with is when the left side is a local variable reference whose
2628 -- value is not currently known to be valid. If this is the case,
2629 -- and the assignment appears in an unconditional context, then
2630 -- we can mark the left side as now being valid if one of these
2631 -- conditions holds:
2633 -- The expression of the right side has Do_Range_Check set so
2634 -- that we know a range check will be performed. Note that it
2635 -- can be the case that a range check is omitted because we
2636 -- make the assumption that we can assume validity for operands
2637 -- appearing in the right side in determining whether a range
2638 -- check is required
2640 -- The subtype of the right side matches the subtype of the
2641 -- left side. In this case, even though we have not checked
2642 -- the range of the right side, we know it is in range of its
2643 -- subtype if the expression is valid.
2645 if Is_Local_Variable_Reference
(Lhs
)
2646 and then not Is_Known_Valid
(Entity
(Lhs
))
2647 and then In_Unconditional_Context
(N
)
2649 if Do_Range_Check
(Rhs
)
2650 or else Etype
(Lhs
) = Etype
(Rhs
)
2652 Set_Is_Known_Valid
(Entity
(Lhs
), True);
2656 -- Case where right side may be invalid in the sense of the RM
2657 -- reference above. The RM does not require that we check for the
2658 -- validity on an assignment, but it does require that the assignment
2659 -- of an invalid value not cause erroneous behavior.
2661 -- The general approach in GNAT is to use the Is_Known_Valid flag
2662 -- to avoid the need for validity checking on assignments. However
2663 -- in some cases, we have to do validity checking in order to make
2664 -- sure that the setting of this flag is correct.
2667 -- Validate right side if we are validating copies
2669 if Validity_Checks_On
2670 and then Validity_Check_Copies
2672 -- Skip this if left hand side is an array or record component
2673 -- and elementary component validity checks are suppressed.
2675 if Nkind_In
(Lhs
, N_Selected_Component
, N_Indexed_Component
)
2676 and then not Validity_Check_Components
2683 -- We can propagate this to the left side where appropriate
2685 if Is_Local_Variable_Reference
(Lhs
)
2686 and then not Is_Known_Valid
(Entity
(Lhs
))
2687 and then In_Unconditional_Context
(N
)
2689 Set_Is_Known_Valid
(Entity
(Lhs
), True);
2692 -- Otherwise check to see what should be done
2694 -- If left side is a local variable, then we just set its flag to
2695 -- indicate that its value may no longer be valid, since we are
2696 -- copying a potentially invalid value.
2698 elsif Is_Local_Variable_Reference
(Lhs
) then
2699 Set_Is_Known_Valid
(Entity
(Lhs
), False);
2701 -- Check for case of a nonlocal variable on the left side which
2702 -- is currently known to be valid. In this case, we simply ensure
2703 -- that the right side is valid. We only play the game of copying
2704 -- validity status for local variables, since we are doing this
2705 -- statically, not by tracing the full flow graph.
2707 elsif Is_Entity_Name
(Lhs
)
2708 and then Is_Known_Valid
(Entity
(Lhs
))
2710 -- Note: If Validity_Checking mode is set to none, we ignore
2711 -- the Ensure_Valid call so don't worry about that case here.
2715 -- In all other cases, we can safely copy an invalid value without
2716 -- worrying about the status of the left side. Since it is not a
2717 -- variable reference it will not be considered
2718 -- as being known to be valid in any case.
2727 when RE_Not_Available
=>
2729 end Expand_N_Assignment_Statement
;
2731 ------------------------------
2732 -- Expand_N_Block_Statement --
2733 ------------------------------
2735 -- Encode entity names defined in block statement
2737 procedure Expand_N_Block_Statement
(N
: Node_Id
) is
2739 Qualify_Entity_Names
(N
);
2740 end Expand_N_Block_Statement
;
2742 -----------------------------
2743 -- Expand_N_Case_Statement --
2744 -----------------------------
2746 procedure Expand_N_Case_Statement
(N
: Node_Id
) is
2747 Loc
: constant Source_Ptr
:= Sloc
(N
);
2748 Expr
: constant Node_Id
:= Expression
(N
);
2756 -- Check for the situation where we know at compile time which branch
2759 if Compile_Time_Known_Value
(Expr
) then
2760 Alt
:= Find_Static_Alternative
(N
);
2762 Process_Statements_For_Controlled_Objects
(Alt
);
2764 -- Move statements from this alternative after the case statement.
2765 -- They are already analyzed, so will be skipped by the analyzer.
2767 Insert_List_After
(N
, Statements
(Alt
));
2769 -- That leaves the case statement as a shell. So now we can kill all
2770 -- other alternatives in the case statement.
2772 Kill_Dead_Code
(Expression
(N
));
2778 -- Loop through case alternatives, skipping pragmas, and skipping
2779 -- the one alternative that we select (and therefore retain).
2781 Dead_Alt
:= First
(Alternatives
(N
));
2782 while Present
(Dead_Alt
) loop
2784 and then Nkind
(Dead_Alt
) = N_Case_Statement_Alternative
2786 Kill_Dead_Code
(Statements
(Dead_Alt
), Warn_On_Deleted_Code
);
2793 Rewrite
(N
, Make_Null_Statement
(Loc
));
2797 -- Here if the choice is not determined at compile time
2800 Last_Alt
: constant Node_Id
:= Last
(Alternatives
(N
));
2802 Others_Present
: Boolean;
2803 Others_Node
: Node_Id
;
2805 Then_Stms
: List_Id
;
2806 Else_Stms
: List_Id
;
2809 if Nkind
(First
(Discrete_Choices
(Last_Alt
))) = N_Others_Choice
then
2810 Others_Present
:= True;
2811 Others_Node
:= Last_Alt
;
2813 Others_Present
:= False;
2816 -- First step is to worry about possible invalid argument. The RM
2817 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
2818 -- outside the base range), then Constraint_Error must be raised.
2820 -- Case of validity check required (validity checks are on, the
2821 -- expression is not known to be valid, and the case statement
2822 -- comes from source -- no need to validity check internally
2823 -- generated case statements).
2825 if Validity_Check_Default
then
2826 Ensure_Valid
(Expr
);
2829 -- If there is only a single alternative, just replace it with the
2830 -- sequence of statements since obviously that is what is going to
2831 -- be executed in all cases.
2833 Len
:= List_Length
(Alternatives
(N
));
2837 -- We still need to evaluate the expression if it has any side
2840 Remove_Side_Effects
(Expression
(N
));
2842 Alt
:= First
(Alternatives
(N
));
2844 Process_Statements_For_Controlled_Objects
(Alt
);
2845 Insert_List_After
(N
, Statements
(Alt
));
2847 -- That leaves the case statement as a shell. The alternative that
2848 -- will be executed is reset to a null list. So now we can kill
2849 -- the entire case statement.
2851 Kill_Dead_Code
(Expression
(N
));
2852 Rewrite
(N
, Make_Null_Statement
(Loc
));
2855 -- An optimization. If there are only two alternatives, and only
2856 -- a single choice, then rewrite the whole case statement as an
2857 -- if statement, since this can result in subsequent optimizations.
2858 -- This helps not only with case statements in the source of a
2859 -- simple form, but also with generated code (discriminant check
2860 -- functions in particular)
2863 Chlist
:= Discrete_Choices
(First
(Alternatives
(N
)));
2865 if List_Length
(Chlist
) = 1 then
2866 Choice
:= First
(Chlist
);
2868 Then_Stms
:= Statements
(First
(Alternatives
(N
)));
2869 Else_Stms
:= Statements
(Last
(Alternatives
(N
)));
2871 -- For TRUE, generate "expression", not expression = true
2873 if Nkind
(Choice
) = N_Identifier
2874 and then Entity
(Choice
) = Standard_True
2876 Cond
:= Expression
(N
);
2878 -- For FALSE, generate "expression" and switch then/else
2880 elsif Nkind
(Choice
) = N_Identifier
2881 and then Entity
(Choice
) = Standard_False
2883 Cond
:= Expression
(N
);
2884 Else_Stms
:= Statements
(First
(Alternatives
(N
)));
2885 Then_Stms
:= Statements
(Last
(Alternatives
(N
)));
2887 -- For a range, generate "expression in range"
2889 elsif Nkind
(Choice
) = N_Range
2890 or else (Nkind
(Choice
) = N_Attribute_Reference
2891 and then Attribute_Name
(Choice
) = Name_Range
)
2892 or else (Is_Entity_Name
(Choice
)
2893 and then Is_Type
(Entity
(Choice
)))
2894 or else Nkind
(Choice
) = N_Subtype_Indication
2898 Left_Opnd
=> Expression
(N
),
2899 Right_Opnd
=> Relocate_Node
(Choice
));
2901 -- For any other subexpression "expression = value"
2906 Left_Opnd
=> Expression
(N
),
2907 Right_Opnd
=> Relocate_Node
(Choice
));
2910 -- Now rewrite the case as an IF
2913 Make_If_Statement
(Loc
,
2915 Then_Statements
=> Then_Stms
,
2916 Else_Statements
=> Else_Stms
));
2922 -- If the last alternative is not an Others choice, replace it with
2923 -- an N_Others_Choice. Note that we do not bother to call Analyze on
2924 -- the modified case statement, since it's only effect would be to
2925 -- compute the contents of the Others_Discrete_Choices which is not
2926 -- needed by the back end anyway.
2928 -- The reason we do this is that the back end always needs some
2929 -- default for a switch, so if we have not supplied one in the
2930 -- processing above for validity checking, then we need to supply
2933 if not Others_Present
then
2934 Others_Node
:= Make_Others_Choice
(Sloc
(Last_Alt
));
2935 Set_Others_Discrete_Choices
2936 (Others_Node
, Discrete_Choices
(Last_Alt
));
2937 Set_Discrete_Choices
(Last_Alt
, New_List
(Others_Node
));
2940 Alt
:= First
(Alternatives
(N
));
2942 and then Nkind
(Alt
) = N_Case_Statement_Alternative
2944 Process_Statements_For_Controlled_Objects
(Alt
);
2948 end Expand_N_Case_Statement
;
2950 -----------------------------
2951 -- Expand_N_Exit_Statement --
2952 -----------------------------
2954 -- The only processing required is to deal with a possible C/Fortran
2955 -- boolean value used as the condition for the exit statement.
2957 procedure Expand_N_Exit_Statement
(N
: Node_Id
) is
2959 Adjust_Condition
(Condition
(N
));
2960 end Expand_N_Exit_Statement
;
2962 -----------------------------
2963 -- Expand_N_Goto_Statement --
2964 -----------------------------
2966 -- Add poll before goto if polling active
2968 procedure Expand_N_Goto_Statement
(N
: Node_Id
) is
2970 Generate_Poll_Call
(N
);
2971 end Expand_N_Goto_Statement
;
2973 ---------------------------
2974 -- Expand_N_If_Statement --
2975 ---------------------------
2977 -- First we deal with the case of C and Fortran convention boolean values,
2978 -- with zero/non-zero semantics.
2980 -- Second, we deal with the obvious rewriting for the cases where the
2981 -- condition of the IF is known at compile time to be True or False.
2983 -- Third, we remove elsif parts which have non-empty Condition_Actions and
2984 -- rewrite as independent if statements. For example:
2995 -- <<condition actions of y>>
3001 -- This rewriting is needed if at least one elsif part has a non-empty
3002 -- Condition_Actions list. We also do the same processing if there is a
3003 -- constant condition in an elsif part (in conjunction with the first
3004 -- processing step mentioned above, for the recursive call made to deal
3005 -- with the created inner if, this deals with properly optimizing the
3006 -- cases of constant elsif conditions).
3008 procedure Expand_N_If_Statement
(N
: Node_Id
) is
3009 Loc
: constant Source_Ptr
:= Sloc
(N
);
3014 Warn_If_Deleted
: constant Boolean :=
3015 Warn_On_Deleted_Code
and then Comes_From_Source
(N
);
3016 -- Indicates whether we want warnings when we delete branches of the
3017 -- if statement based on constant condition analysis. We never want
3018 -- these warnings for expander generated code.
3021 Process_Statements_For_Controlled_Objects
(N
);
3023 Adjust_Condition
(Condition
(N
));
3025 -- The following loop deals with constant conditions for the IF. We
3026 -- need a loop because as we eliminate False conditions, we grab the
3027 -- first elsif condition and use it as the primary condition.
3029 while Compile_Time_Known_Value
(Condition
(N
)) loop
3031 -- If condition is True, we can simply rewrite the if statement now
3032 -- by replacing it by the series of then statements.
3034 if Is_True
(Expr_Value
(Condition
(N
))) then
3036 -- All the else parts can be killed
3038 Kill_Dead_Code
(Elsif_Parts
(N
), Warn_If_Deleted
);
3039 Kill_Dead_Code
(Else_Statements
(N
), Warn_If_Deleted
);
3041 Hed
:= Remove_Head
(Then_Statements
(N
));
3042 Insert_List_After
(N
, Then_Statements
(N
));
3046 -- If condition is False, then we can delete the condition and
3047 -- the Then statements
3050 -- We do not delete the condition if constant condition warnings
3051 -- are enabled, since otherwise we end up deleting the desired
3052 -- warning. Of course the backend will get rid of this True/False
3053 -- test anyway, so nothing is lost here.
3055 if not Constant_Condition_Warnings
then
3056 Kill_Dead_Code
(Condition
(N
));
3059 Kill_Dead_Code
(Then_Statements
(N
), Warn_If_Deleted
);
3061 -- If there are no elsif statements, then we simply replace the
3062 -- entire if statement by the sequence of else statements.
3064 if No
(Elsif_Parts
(N
)) then
3065 if No
(Else_Statements
(N
))
3066 or else Is_Empty_List
(Else_Statements
(N
))
3069 Make_Null_Statement
(Sloc
(N
)));
3071 Hed
:= Remove_Head
(Else_Statements
(N
));
3072 Insert_List_After
(N
, Else_Statements
(N
));
3078 -- If there are elsif statements, the first of them becomes the
3079 -- if/then section of the rebuilt if statement This is the case
3080 -- where we loop to reprocess this copied condition.
3083 Hed
:= Remove_Head
(Elsif_Parts
(N
));
3084 Insert_Actions
(N
, Condition_Actions
(Hed
));
3085 Set_Condition
(N
, Condition
(Hed
));
3086 Set_Then_Statements
(N
, Then_Statements
(Hed
));
3088 -- Hed might have been captured as the condition determining
3089 -- the current value for an entity. Now it is detached from
3090 -- the tree, so a Current_Value pointer in the condition might
3091 -- need to be updated.
3093 Set_Current_Value_Condition
(N
);
3095 if Is_Empty_List
(Elsif_Parts
(N
)) then
3096 Set_Elsif_Parts
(N
, No_List
);
3102 -- Loop through elsif parts, dealing with constant conditions and
3103 -- possible condition actions that are present.
3105 if Present
(Elsif_Parts
(N
)) then
3106 E
:= First
(Elsif_Parts
(N
));
3107 while Present
(E
) loop
3108 Process_Statements_For_Controlled_Objects
(E
);
3110 Adjust_Condition
(Condition
(E
));
3112 -- If there are condition actions, then rewrite the if statement
3113 -- as indicated above. We also do the same rewrite for a True or
3114 -- False condition. The further processing of this constant
3115 -- condition is then done by the recursive call to expand the
3116 -- newly created if statement
3118 if Present
(Condition_Actions
(E
))
3119 or else Compile_Time_Known_Value
(Condition
(E
))
3121 -- Note this is not an implicit if statement, since it is part
3122 -- of an explicit if statement in the source (or of an implicit
3123 -- if statement that has already been tested).
3126 Make_If_Statement
(Sloc
(E
),
3127 Condition
=> Condition
(E
),
3128 Then_Statements
=> Then_Statements
(E
),
3129 Elsif_Parts
=> No_List
,
3130 Else_Statements
=> Else_Statements
(N
));
3132 -- Elsif parts for new if come from remaining elsif's of parent
3134 while Present
(Next
(E
)) loop
3135 if No
(Elsif_Parts
(New_If
)) then
3136 Set_Elsif_Parts
(New_If
, New_List
);
3139 Append
(Remove_Next
(E
), Elsif_Parts
(New_If
));
3142 Set_Else_Statements
(N
, New_List
(New_If
));
3144 if Present
(Condition_Actions
(E
)) then
3145 Insert_List_Before
(New_If
, Condition_Actions
(E
));
3150 if Is_Empty_List
(Elsif_Parts
(N
)) then
3151 Set_Elsif_Parts
(N
, No_List
);
3157 -- No special processing for that elsif part, move to next
3165 -- Some more optimizations applicable if we still have an IF statement
3167 if Nkind
(N
) /= N_If_Statement
then
3171 -- Another optimization, special cases that can be simplified
3173 -- if expression then
3179 -- can be changed to:
3181 -- return expression;
3185 -- if expression then
3191 -- can be changed to:
3193 -- return not (expression);
3195 -- Only do these optimizations if we are at least at -O1 level and
3196 -- do not do them if control flow optimizations are suppressed.
3198 if Optimization_Level
> 0
3199 and then not Opt
.Suppress_Control_Flow_Optimizations
3201 if Nkind
(N
) = N_If_Statement
3202 and then No
(Elsif_Parts
(N
))
3203 and then Present
(Else_Statements
(N
))
3204 and then List_Length
(Then_Statements
(N
)) = 1
3205 and then List_Length
(Else_Statements
(N
)) = 1
3208 Then_Stm
: constant Node_Id
:= First
(Then_Statements
(N
));
3209 Else_Stm
: constant Node_Id
:= First
(Else_Statements
(N
));
3212 if Nkind
(Then_Stm
) = N_Simple_Return_Statement
3214 Nkind
(Else_Stm
) = N_Simple_Return_Statement
3217 Then_Expr
: constant Node_Id
:= Expression
(Then_Stm
);
3218 Else_Expr
: constant Node_Id
:= Expression
(Else_Stm
);
3221 if Nkind
(Then_Expr
) = N_Identifier
3223 Nkind
(Else_Expr
) = N_Identifier
3225 if Entity
(Then_Expr
) = Standard_True
3226 and then Entity
(Else_Expr
) = Standard_False
3229 Make_Simple_Return_Statement
(Loc
,
3230 Expression
=> Relocate_Node
(Condition
(N
))));
3234 elsif Entity
(Then_Expr
) = Standard_False
3235 and then Entity
(Else_Expr
) = Standard_True
3238 Make_Simple_Return_Statement
(Loc
,
3242 Relocate_Node
(Condition
(N
)))));
3252 end Expand_N_If_Statement
;
3254 --------------------------
3255 -- Expand_Iterator_Loop --
3256 --------------------------
3258 procedure Expand_Iterator_Loop
(N
: Node_Id
) is
3259 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
3260 I_Spec
: constant Node_Id
:= Iterator_Specification
(Isc
);
3261 Id
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
3262 Loc
: constant Source_Ptr
:= Sloc
(N
);
3264 Container
: constant Node_Id
:= Name
(I_Spec
);
3265 Container_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Container
));
3267 Iterator
: Entity_Id
;
3269 Stats
: List_Id
:= Statements
(N
);
3272 -- Processing for arrays
3274 if Is_Array_Type
(Container_Typ
) then
3275 Expand_Iterator_Loop_Over_Array
(N
);
3279 -- Processing for containers
3281 -- For an "of" iterator the name is a container expression, which
3282 -- is transformed into a call to the default iterator.
3284 -- For an iterator of the form "in" the name is a function call
3285 -- that delivers an iterator type.
3287 -- In both cases, analysis of the iterator has introduced an object
3288 -- declaration to capture the domain, so that Container is an entity.
3290 -- The for loop is expanded into a while loop which uses a container
3291 -- specific cursor to desgnate each element.
3293 -- Iter : Iterator_Type := Container.Iterate;
3294 -- Cursor : Cursor_type := First (Iter);
3295 -- while Has_Element (Iter) loop
3297 -- -- The block is added when Element_Type is controlled
3299 -- Obj : Pack.Element_Type := Element (Cursor);
3300 -- -- for the "of" loop form
3302 -- <original loop statements>
3305 -- Cursor := Iter.Next (Cursor);
3308 -- If "reverse" is present, then the initialization of the cursor
3309 -- uses Last and the step becomes Prev. Pack is the name of the
3310 -- scope where the container package is instantiated.
3313 Element_Type
: constant Entity_Id
:= Etype
(Id
);
3314 Iter_Type
: Entity_Id
;
3317 Name_Init
: Name_Id
;
3318 Name_Step
: Name_Id
;
3321 -- The type of the iterator is the return type of the Iterate
3322 -- function used. For the "of" form this is the default iterator
3323 -- for the type, otherwise it is the type of the explicit
3324 -- function used in the iterator specification. The most common
3325 -- case will be an Iterate function in the container package.
3327 -- The primitive operations of the container type may not be
3328 -- use-visible, so we introduce the name of the enclosing package
3329 -- in the declarations below. The Iterator type is declared in a
3330 -- an instance within the container package itself.
3332 -- If the container type is a derived type, the cursor type is
3333 -- found in the package of the parent type.
3335 if Is_Derived_Type
(Container_Typ
) then
3336 Pack
:= Scope
(Root_Type
(Container_Typ
));
3338 Pack
:= Scope
(Container_Typ
);
3341 Iter_Type
:= Etype
(Name
(I_Spec
));
3343 -- The "of" case uses an internally generated cursor whose type
3344 -- is found in the container package. The domain of iteration
3345 -- is expanded into a call to the default Iterator function, but
3346 -- this expansion does not take place in quantified expressions
3347 -- that are analyzed with expansion disabled, and in that case the
3348 -- type of the iterator must be obtained from the aspect.
3350 if Of_Present
(I_Spec
) then
3352 Default_Iter
: constant Entity_Id
:=
3356 Aspect_Default_Iterator
));
3358 Container_Arg
: Node_Id
;
3362 Cursor
:= Make_Temporary
(Loc
, 'I');
3364 -- For an container element iterator, the iterator type
3365 -- is obtained from the corresponding aspect, whose return
3366 -- type is descended from the corresponding interface type
3367 -- in some instance of Ada.Iterator_Interfaces. The actuals
3368 -- of that instantiation are Cursor and Has_Element.
3370 Iter_Type
:= Etype
(Default_Iter
);
3372 -- The iterator type, which is a class_wide type, may itself
3373 -- be derived locally, so the desired instantiation is the
3374 -- scope of the root type of the iterator type.
3376 Pack
:= Scope
(Root_Type
(Etype
(Iter_Type
)));
3378 -- Rewrite domain of iteration as a call to the default
3379 -- iterator for the container type. If the container is
3380 -- a derived type and the aspect is inherited, convert
3381 -- container to parent type. The Cursor type is also
3382 -- inherited from the scope of the parent.
3384 if Base_Type
(Etype
(Container
)) =
3385 Base_Type
(Etype
(First_Formal
(Default_Iter
)))
3387 Container_Arg
:= New_Copy_Tree
(Container
);
3391 Make_Type_Conversion
(Loc
,
3394 (Etype
(First_Formal
(Default_Iter
)), Loc
),
3395 Expression
=> New_Copy_Tree
(Container
));
3398 Rewrite
(Name
(I_Spec
),
3399 Make_Function_Call
(Loc
,
3400 Name
=> New_Occurrence_Of
(Default_Iter
, Loc
),
3401 Parameter_Associations
=>
3402 New_List
(Container_Arg
)));
3403 Analyze_And_Resolve
(Name
(I_Spec
));
3405 -- Find cursor type in proper iterator package, which is an
3406 -- instantiation of Iterator_Interfaces.
3408 Ent
:= First_Entity
(Pack
);
3409 while Present
(Ent
) loop
3410 if Chars
(Ent
) = Name_Cursor
then
3411 Set_Etype
(Cursor
, Etype
(Ent
));
3418 -- Id : Element_Type renames Container (Cursor);
3419 -- This assumes that the container type has an indexing
3420 -- operation with Cursor. The check that this operation
3421 -- exists is performed in Check_Container_Indexing.
3424 Make_Object_Renaming_Declaration
(Loc
,
3425 Defining_Identifier
=> Id
,
3427 New_Reference_To
(Element_Type
, Loc
),
3429 Make_Indexed_Component
(Loc
,
3430 Prefix
=> Relocate_Node
(Container_Arg
),
3432 New_List
(New_Occurrence_Of
(Cursor
, Loc
))));
3434 -- The defining identifier in the iterator is user-visible
3435 -- and must be visible in the debugger.
3437 Set_Debug_Info_Needed
(Id
);
3439 -- If the container holds controlled objects, wrap the loop
3440 -- statements and element renaming declaration with a block.
3441 -- This ensures that the result of Element (Cusor) is
3442 -- cleaned up after each iteration of the loop.
3444 if Needs_Finalization
(Element_Type
) then
3448 -- Id : Element_Type := Element (curosr);
3450 -- <original loop statements>
3454 Make_Block_Statement
(Loc
,
3455 Declarations
=> New_List
(Decl
),
3456 Handled_Statement_Sequence
=>
3457 Make_Handled_Sequence_Of_Statements
(Loc
,
3458 Statements
=> Stats
)));
3460 -- Elements do not need finalization
3463 Prepend_To
(Stats
, Decl
);
3467 -- X in Iterate (S) : type of iterator is type of explicitly
3468 -- given Iterate function, and the loop variable is the cursor.
3469 -- It will be assigned in the loop and must be a variable.
3473 Set_Ekind
(Cursor
, E_Variable
);
3476 Iterator
:= Make_Temporary
(Loc
, 'I');
3478 -- Determine the advancement and initialization steps for the
3481 -- Analysis of the expanded loop will verify that the container
3482 -- has a reverse iterator.
3484 if Reverse_Present
(I_Spec
) then
3485 Name_Init
:= Name_Last
;
3486 Name_Step
:= Name_Previous
;
3489 Name_Init
:= Name_First
;
3490 Name_Step
:= Name_Next
;
3493 -- For both iterator forms, add a call to the step operation to
3494 -- advance the cursor. Generate:
3496 -- Cursor := Iterator.Next (Cursor);
3500 -- Cursor := Next (Cursor);
3507 Make_Function_Call
(Loc
,
3509 Make_Selected_Component
(Loc
,
3510 Prefix
=> New_Reference_To
(Iterator
, Loc
),
3511 Selector_Name
=> Make_Identifier
(Loc
, Name_Step
)),
3512 Parameter_Associations
=> New_List
(
3513 New_Reference_To
(Cursor
, Loc
)));
3516 Make_Assignment_Statement
(Loc
,
3517 Name
=> New_Occurrence_Of
(Cursor
, Loc
),
3518 Expression
=> Rhs
));
3522 -- while Iterator.Has_Element loop
3526 -- Has_Element is the second actual in the iterator package
3529 Make_Loop_Statement
(Loc
,
3531 Make_Iteration_Scheme
(Loc
,
3533 Make_Function_Call
(Loc
,
3536 Next_Entity
(First_Entity
(Pack
)), Loc
),
3537 Parameter_Associations
=>
3538 New_List
(New_Reference_To
(Cursor
, Loc
)))),
3540 Statements
=> Stats
,
3541 End_Label
=> Empty
);
3543 -- If present, preserve identifier of loop, which can be used in
3544 -- an exit statement in the body.
3546 if Present
(Identifier
(N
)) then
3547 Set_Identifier
(New_Loop
, Relocate_Node
(Identifier
(N
)));
3550 -- Create the declarations for Iterator and cursor and insert them
3551 -- before the source loop. Given that the domain of iteration is
3552 -- already an entity, the iterator is just a renaming of that
3553 -- entity. Possible optimization ???
3556 -- I : Iterator_Type renames Container;
3557 -- C : Cursor_Type := Container.[First | Last];
3560 Make_Object_Renaming_Declaration
(Loc
,
3561 Defining_Identifier
=> Iterator
,
3562 Subtype_Mark
=> New_Occurrence_Of
(Iter_Type
, Loc
),
3563 Name
=> Relocate_Node
(Name
(I_Spec
))));
3565 -- Create declaration for cursor
3572 Make_Object_Declaration
(Loc
,
3573 Defining_Identifier
=> Cursor
,
3574 Object_Definition
=>
3575 New_Occurrence_Of
(Etype
(Cursor
), Loc
),
3577 Make_Selected_Component
(Loc
,
3578 Prefix
=> New_Reference_To
(Iterator
, Loc
),
3580 Make_Identifier
(Loc
, Name_Init
)));
3582 -- The cursor is only modified in expanded code, so it appears
3583 -- as unassigned to the warning machinery. We must suppress
3584 -- this spurious warning explicitly.
3586 Set_Warnings_Off
(Cursor
);
3587 Set_Assignment_OK
(Decl
);
3589 Insert_Action
(N
, Decl
);
3592 -- If the range of iteration is given by a function call that
3593 -- returns a container, the finalization actions have been saved
3594 -- in the Condition_Actions of the iterator. Insert them now at
3595 -- the head of the loop.
3597 if Present
(Condition_Actions
(Isc
)) then
3598 Insert_List_Before
(N
, Condition_Actions
(Isc
));
3602 Rewrite
(N
, New_Loop
);
3604 end Expand_Iterator_Loop
;
3606 -------------------------------------
3607 -- Expand_Iterator_Loop_Over_Array --
3608 -------------------------------------
3610 procedure Expand_Iterator_Loop_Over_Array
(N
: Node_Id
) is
3611 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
3612 I_Spec
: constant Node_Id
:= Iterator_Specification
(Isc
);
3613 Array_Node
: constant Node_Id
:= Name
(I_Spec
);
3614 Array_Typ
: constant Entity_Id
:= Base_Type
(Etype
(Array_Node
));
3615 Array_Dim
: constant Pos
:= Number_Dimensions
(Array_Typ
);
3616 Id
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
3617 Loc
: constant Source_Ptr
:= Sloc
(N
);
3618 Stats
: constant List_Id
:= Statements
(N
);
3619 Core_Loop
: Node_Id
;
3621 Iterator
: Entity_Id
;
3623 -- Start of processing for Expand_Iterator_Loop_Over_Array
3626 -- for Element of Array loop
3628 -- This case requires an internally generated cursor to iterate over
3631 if Of_Present
(I_Spec
) then
3632 Iterator
:= Make_Temporary
(Loc
, 'C');
3635 -- Element : Component_Type renames Array (Iterator);
3638 Make_Indexed_Component
(Loc
,
3639 Prefix
=> Relocate_Node
(Array_Node
),
3640 Expressions
=> New_List
(New_Reference_To
(Iterator
, Loc
)));
3643 Make_Object_Renaming_Declaration
(Loc
,
3644 Defining_Identifier
=> Id
,
3646 New_Reference_To
(Component_Type
(Array_Typ
), Loc
),
3649 -- Mark the loop variable as needing debug info, so that expansion
3650 -- of the renaming will result in Materialize_Entity getting set via
3651 -- Debug_Renaming_Declaration. (This setting is needed here because
3652 -- the setting in Freeze_Entity comes after the expansion, which is
3655 Set_Debug_Info_Needed
(Id
);
3657 -- for Index in Array loop
3659 -- This case utilizes the already given iterator name
3667 -- for Iterator in [reverse] Array'Range (Array_Dim) loop
3668 -- Element : Component_Type renames Array (Iterator);
3669 -- <original loop statements>
3673 Make_Loop_Statement
(Loc
,
3675 Make_Iteration_Scheme
(Loc
,
3676 Loop_Parameter_Specification
=>
3677 Make_Loop_Parameter_Specification
(Loc
,
3678 Defining_Identifier
=> Iterator
,
3679 Discrete_Subtype_Definition
=>
3680 Make_Attribute_Reference
(Loc
,
3681 Prefix
=> Relocate_Node
(Array_Node
),
3682 Attribute_Name
=> Name_Range
,
3683 Expressions
=> New_List
(
3684 Make_Integer_Literal
(Loc
, Array_Dim
))),
3685 Reverse_Present
=> Reverse_Present
(I_Spec
))),
3686 Statements
=> Stats
,
3687 End_Label
=> Empty
);
3689 -- Processing for multidimensional array
3691 if Array_Dim
> 1 then
3692 for Dim
in 1 .. Array_Dim
- 1 loop
3693 Iterator
:= Make_Temporary
(Loc
, 'C');
3695 -- Generate the dimension loops starting from the innermost one
3697 -- for Iterator in [reverse] Array'Range (Array_Dim - Dim) loop
3702 Make_Loop_Statement
(Loc
,
3704 Make_Iteration_Scheme
(Loc
,
3705 Loop_Parameter_Specification
=>
3706 Make_Loop_Parameter_Specification
(Loc
,
3707 Defining_Identifier
=> Iterator
,
3708 Discrete_Subtype_Definition
=>
3709 Make_Attribute_Reference
(Loc
,
3710 Prefix
=> Relocate_Node
(Array_Node
),
3711 Attribute_Name
=> Name_Range
,
3712 Expressions
=> New_List
(
3713 Make_Integer_Literal
(Loc
, Array_Dim
- Dim
))),
3714 Reverse_Present
=> Reverse_Present
(I_Spec
))),
3715 Statements
=> New_List
(Core_Loop
),
3716 End_Label
=> Empty
);
3718 -- Update the previously created object renaming declaration with
3719 -- the new iterator.
3721 Prepend_To
(Expressions
(Ind_Comp
),
3722 New_Reference_To
(Iterator
, Loc
));
3726 -- If original loop has a name, preserve it so it can be recognized by
3727 -- an exit statement in the body of the rewritten loop.
3729 if Present
(Identifier
(N
)) then
3730 Set_Identifier
(Core_Loop
, Relocate_Node
(Identifier
(N
)));
3733 Rewrite
(N
, Core_Loop
);
3735 end Expand_Iterator_Loop_Over_Array
;
3737 -----------------------------
3738 -- Expand_N_Loop_Statement --
3739 -----------------------------
3741 -- 1. Remove null loop entirely
3742 -- 2. Deal with while condition for C/Fortran boolean
3743 -- 3. Deal with loops with a non-standard enumeration type range
3744 -- 4. Deal with while loops where Condition_Actions is set
3745 -- 5. Deal with loops over predicated subtypes
3746 -- 6. Deal with loops with iterators over arrays and containers
3747 -- 7. Insert polling call if required
3749 procedure Expand_N_Loop_Statement
(N
: Node_Id
) is
3750 Loc
: constant Source_Ptr
:= Sloc
(N
);
3751 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
3756 if Is_Null_Loop
(N
) then
3757 Rewrite
(N
, Make_Null_Statement
(Loc
));
3761 Process_Statements_For_Controlled_Objects
(N
);
3763 -- Deal with condition for C/Fortran Boolean
3765 if Present
(Isc
) then
3766 Adjust_Condition
(Condition
(Isc
));
3769 -- Generate polling call
3771 if Is_Non_Empty_List
(Statements
(N
)) then
3772 Generate_Poll_Call
(First
(Statements
(N
)));
3775 -- Nothing more to do for plain loop with no iteration scheme
3780 -- Case of for loop (Loop_Parameter_Specification present)
3782 -- Note: we do not have to worry about validity checking of the for loop
3783 -- range bounds here, since they were frozen with constant declarations
3784 -- and it is during that process that the validity checking is done.
3786 elsif Present
(Loop_Parameter_Specification
(Isc
)) then
3788 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Isc
);
3789 Loop_Id
: constant Entity_Id
:= Defining_Identifier
(LPS
);
3790 Ltype
: constant Entity_Id
:= Etype
(Loop_Id
);
3791 Btype
: constant Entity_Id
:= Base_Type
(Ltype
);
3796 -- Deal with loop over predicates
3798 if Is_Discrete_Type
(Ltype
)
3799 and then Present
(Predicate_Function
(Ltype
))
3801 Expand_Predicated_Loop
(N
);
3803 -- Handle the case where we have a for loop with the range type
3804 -- being an enumeration type with non-standard representation.
3805 -- In this case we expand:
3807 -- for x in [reverse] a .. b loop
3813 -- for xP in [reverse] integer
3814 -- range etype'Pos (a) .. etype'Pos (b)
3817 -- x : constant etype := Pos_To_Rep (xP);
3823 elsif Is_Enumeration_Type
(Btype
)
3824 and then Present
(Enum_Pos_To_Rep
(Btype
))
3827 Make_Defining_Identifier
(Loc
,
3828 Chars
=> New_External_Name
(Chars
(Loop_Id
), 'P'));
3830 -- If the type has a contiguous representation, successive
3831 -- values can be generated as offsets from the first literal.
3833 if Has_Contiguous_Rep
(Btype
) then
3835 Unchecked_Convert_To
(Btype
,
3838 Make_Integer_Literal
(Loc
,
3839 Enumeration_Rep
(First_Literal
(Btype
))),
3840 Right_Opnd
=> New_Reference_To
(New_Id
, Loc
)));
3842 -- Use the constructed array Enum_Pos_To_Rep
3845 Make_Indexed_Component
(Loc
,
3847 New_Reference_To
(Enum_Pos_To_Rep
(Btype
), Loc
),
3849 New_List
(New_Reference_To
(New_Id
, Loc
)));
3853 Make_Loop_Statement
(Loc
,
3854 Identifier
=> Identifier
(N
),
3857 Make_Iteration_Scheme
(Loc
,
3858 Loop_Parameter_Specification
=>
3859 Make_Loop_Parameter_Specification
(Loc
,
3860 Defining_Identifier
=> New_Id
,
3861 Reverse_Present
=> Reverse_Present
(LPS
),
3863 Discrete_Subtype_Definition
=>
3864 Make_Subtype_Indication
(Loc
,
3867 New_Reference_To
(Standard_Natural
, Loc
),
3870 Make_Range_Constraint
(Loc
,
3875 Make_Attribute_Reference
(Loc
,
3877 New_Reference_To
(Btype
, Loc
),
3879 Attribute_Name
=> Name_Pos
,
3881 Expressions
=> New_List
(
3883 (Type_Low_Bound
(Ltype
)))),
3886 Make_Attribute_Reference
(Loc
,
3888 New_Reference_To
(Btype
, Loc
),
3890 Attribute_Name
=> Name_Pos
,
3892 Expressions
=> New_List
(
3897 Statements
=> New_List
(
3898 Make_Block_Statement
(Loc
,
3899 Declarations
=> New_List
(
3900 Make_Object_Declaration
(Loc
,
3901 Defining_Identifier
=> Loop_Id
,
3902 Constant_Present
=> True,
3903 Object_Definition
=>
3904 New_Reference_To
(Ltype
, Loc
),
3905 Expression
=> Expr
)),
3907 Handled_Statement_Sequence
=>
3908 Make_Handled_Sequence_Of_Statements
(Loc
,
3909 Statements
=> Statements
(N
)))),
3911 End_Label
=> End_Label
(N
)));
3913 -- The loop parameter's entity must be removed from the loop
3914 -- scope's entity list, since it will now be located in the
3915 -- new block scope. Any other entities already associated with
3916 -- the loop scope, such as the loop parameter's subtype, will
3919 pragma Assert
(First_Entity
(Scope
(Loop_Id
)) = Loop_Id
);
3920 Set_First_Entity
(Scope
(Loop_Id
), Next_Entity
(Loop_Id
));
3922 if Last_Entity
(Scope
(Loop_Id
)) = Loop_Id
then
3923 Set_Last_Entity
(Scope
(Loop_Id
), Empty
);
3928 -- Nothing to do with other cases of for loops
3935 -- Second case, if we have a while loop with Condition_Actions set, then
3936 -- we change it into a plain loop:
3945 -- <<condition actions>>
3951 and then Present
(Condition_Actions
(Isc
))
3952 and then Present
(Condition
(Isc
))
3959 Make_Exit_Statement
(Sloc
(Condition
(Isc
)),
3961 Make_Op_Not
(Sloc
(Condition
(Isc
)),
3962 Right_Opnd
=> Condition
(Isc
)));
3964 Prepend
(ES
, Statements
(N
));
3965 Insert_List_Before
(ES
, Condition_Actions
(Isc
));
3967 -- This is not an implicit loop, since it is generated in response
3968 -- to the loop statement being processed. If this is itself
3969 -- implicit, the restriction has already been checked. If not,
3970 -- it is an explicit loop.
3973 Make_Loop_Statement
(Sloc
(N
),
3974 Identifier
=> Identifier
(N
),
3975 Statements
=> Statements
(N
),
3976 End_Label
=> End_Label
(N
)));
3981 -- Here to deal with iterator case
3984 and then Present
(Iterator_Specification
(Isc
))
3986 Expand_Iterator_Loop
(N
);
3989 -- If the loop is subject to at least one Loop_Entry attribute, it
3990 -- requires additional processing.
3992 if Nkind
(N
) = N_Loop_Statement
then
3993 Expand_Loop_Entry_Attributes
(N
);
3995 end Expand_N_Loop_Statement
;
3997 ----------------------------
3998 -- Expand_Predicated_Loop --
3999 ----------------------------
4001 -- Note: the expander can handle generation of loops over predicated
4002 -- subtypes for both the dynamic and static cases. Depending on what
4003 -- we decide is allowed in Ada 2012 mode and/or extensions allowed
4004 -- mode, the semantic analyzer may disallow one or both forms.
4006 procedure Expand_Predicated_Loop
(N
: Node_Id
) is
4007 Loc
: constant Source_Ptr
:= Sloc
(N
);
4008 Isc
: constant Node_Id
:= Iteration_Scheme
(N
);
4009 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Isc
);
4010 Loop_Id
: constant Entity_Id
:= Defining_Identifier
(LPS
);
4011 Ltype
: constant Entity_Id
:= Etype
(Loop_Id
);
4012 Stat
: constant List_Id
:= Static_Predicate
(Ltype
);
4013 Stmts
: constant List_Id
:= Statements
(N
);
4016 -- Case of iteration over non-static predicate, should not be possible
4017 -- since this is not allowed by the semantics and should have been
4018 -- caught during analysis of the loop statement.
4021 raise Program_Error
;
4023 -- If the predicate list is empty, that corresponds to a predicate of
4024 -- False, in which case the loop won't run at all, and we rewrite the
4025 -- entire loop as a null statement.
4027 elsif Is_Empty_List
(Stat
) then
4028 Rewrite
(N
, Make_Null_Statement
(Loc
));
4031 -- For expansion over a static predicate we generate the following
4034 -- J : Ltype := min-val;
4039 -- when endpoint => J := startpoint;
4040 -- when endpoint => J := startpoint;
4042 -- when max-val => exit;
4043 -- when others => J := Lval'Succ (J);
4048 -- To make this a little clearer, let's take a specific example:
4050 -- type Int is range 1 .. 10;
4051 -- subtype L is Int with
4052 -- predicate => L in 3 | 10 | 5 .. 7;
4054 -- for L in StaticP loop
4055 -- Put_Line ("static:" & J'Img);
4058 -- In this case, the loop is transformed into
4065 -- when 3 => J := 5;
4066 -- when 7 => J := 10;
4068 -- when others => J := L'Succ (J);
4074 Static_Predicate
: declare
4081 function Lo_Val
(N
: Node_Id
) return Node_Id
;
4082 -- Given static expression or static range, returns an identifier
4083 -- whose value is the low bound of the expression value or range.
4085 function Hi_Val
(N
: Node_Id
) return Node_Id
;
4086 -- Given static expression or static range, returns an identifier
4087 -- whose value is the high bound of the expression value or range.
4093 function Hi_Val
(N
: Node_Id
) return Node_Id
is
4095 if Is_Static_Expression
(N
) then
4096 return New_Copy
(N
);
4098 pragma Assert
(Nkind
(N
) = N_Range
);
4099 return New_Copy
(High_Bound
(N
));
4107 function Lo_Val
(N
: Node_Id
) return Node_Id
is
4109 if Is_Static_Expression
(N
) then
4110 return New_Copy
(N
);
4112 pragma Assert
(Nkind
(N
) = N_Range
);
4113 return New_Copy
(Low_Bound
(N
));
4117 -- Start of processing for Static_Predicate
4120 -- Convert loop identifier to normal variable and reanalyze it so
4121 -- that this conversion works. We have to use the same defining
4122 -- identifier, since there may be references in the loop body.
4124 Set_Analyzed
(Loop_Id
, False);
4125 Set_Ekind
(Loop_Id
, E_Variable
);
4127 -- In most loops the loop variable is assigned in various
4128 -- alternatives in the body. However, in the rare case when
4129 -- the range specifies a single element, the loop variable
4130 -- may trigger a spurious warning that is could be constant.
4131 -- This warning might as well be suppressed.
4133 Set_Warnings_Off
(Loop_Id
);
4135 -- Loop to create branches of case statement
4139 while Present
(P
) loop
4140 if No
(Next
(P
)) then
4141 S
:= Make_Exit_Statement
(Loc
);
4144 Make_Assignment_Statement
(Loc
,
4145 Name
=> New_Occurrence_Of
(Loop_Id
, Loc
),
4146 Expression
=> Lo_Val
(Next
(P
)));
4147 Set_Suppress_Assignment_Checks
(S
);
4151 Make_Case_Statement_Alternative
(Loc
,
4152 Statements
=> New_List
(S
),
4153 Discrete_Choices
=> New_List
(Hi_Val
(P
))));
4158 -- Add others choice
4161 Make_Assignment_Statement
(Loc
,
4162 Name
=> New_Occurrence_Of
(Loop_Id
, Loc
),
4164 Make_Attribute_Reference
(Loc
,
4165 Prefix
=> New_Occurrence_Of
(Ltype
, Loc
),
4166 Attribute_Name
=> Name_Succ
,
4167 Expressions
=> New_List
(
4168 New_Occurrence_Of
(Loop_Id
, Loc
))));
4169 Set_Suppress_Assignment_Checks
(S
);
4172 Make_Case_Statement_Alternative
(Loc
,
4173 Discrete_Choices
=> New_List
(Make_Others_Choice
(Loc
)),
4174 Statements
=> New_List
(S
)));
4176 -- Construct case statement and append to body statements
4179 Make_Case_Statement
(Loc
,
4180 Expression
=> New_Occurrence_Of
(Loop_Id
, Loc
),
4181 Alternatives
=> Alts
);
4182 Append_To
(Stmts
, Cstm
);
4187 Make_Object_Declaration
(Loc
,
4188 Defining_Identifier
=> Loop_Id
,
4189 Object_Definition
=> New_Occurrence_Of
(Ltype
, Loc
),
4190 Expression
=> Lo_Val
(First
(Stat
)));
4191 Set_Suppress_Assignment_Checks
(D
);
4194 Make_Block_Statement
(Loc
,
4195 Declarations
=> New_List
(D
),
4196 Handled_Statement_Sequence
=>
4197 Make_Handled_Sequence_Of_Statements
(Loc
,
4198 Statements
=> New_List
(
4199 Make_Loop_Statement
(Loc
,
4200 Statements
=> Stmts
,
4201 End_Label
=> Empty
)))));
4204 end Static_Predicate
;
4206 end Expand_Predicated_Loop
;
4208 ------------------------------
4209 -- Make_Tag_Ctrl_Assignment --
4210 ------------------------------
4212 function Make_Tag_Ctrl_Assignment
(N
: Node_Id
) return List_Id
is
4213 Asn
: constant Node_Id
:= Relocate_Node
(N
);
4214 L
: constant Node_Id
:= Name
(N
);
4215 Loc
: constant Source_Ptr
:= Sloc
(N
);
4216 Res
: constant List_Id
:= New_List
;
4217 T
: constant Entity_Id
:= Underlying_Type
(Etype
(L
));
4219 Comp_Asn
: constant Boolean := Is_Fully_Repped_Tagged_Type
(T
);
4220 Ctrl_Act
: constant Boolean := Needs_Finalization
(T
)
4221 and then not No_Ctrl_Actions
(N
);
4222 Save_Tag
: constant Boolean := Is_Tagged_Type
(T
)
4223 and then not Comp_Asn
4224 and then not No_Ctrl_Actions
(N
)
4225 and then Tagged_Type_Expansion
;
4226 -- Tags are not saved and restored when VM_Target because VM tags are
4227 -- represented implicitly in objects.
4229 Next_Id
: Entity_Id
;
4230 Prev_Id
: Entity_Id
;
4234 -- Finalize the target of the assignment when controlled
4236 -- We have two exceptions here:
4238 -- 1. If we are in an init proc since it is an initialization more
4239 -- than an assignment.
4241 -- 2. If the left-hand side is a temporary that was not initialized
4242 -- (or the parent part of a temporary since it is the case in
4243 -- extension aggregates). Such a temporary does not come from
4244 -- source. We must examine the original node for the prefix, because
4245 -- it may be a component of an entry formal, in which case it has
4246 -- been rewritten and does not appear to come from source either.
4248 -- Case of init proc
4250 if not Ctrl_Act
then
4253 -- The left hand side is an uninitialized temporary object
4255 elsif Nkind
(L
) = N_Type_Conversion
4256 and then Is_Entity_Name
(Expression
(L
))
4257 and then Nkind
(Parent
(Entity
(Expression
(L
)))) =
4258 N_Object_Declaration
4259 and then No_Initialization
(Parent
(Entity
(Expression
(L
))))
4266 (Obj_Ref
=> Duplicate_Subexpr_No_Checks
(L
),
4270 -- Save the Tag in a local variable Tag_Id
4273 Tag_Id
:= Make_Temporary
(Loc
, 'A');
4276 Make_Object_Declaration
(Loc
,
4277 Defining_Identifier
=> Tag_Id
,
4278 Object_Definition
=> New_Reference_To
(RTE
(RE_Tag
), Loc
),
4280 Make_Selected_Component
(Loc
,
4281 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
4283 New_Reference_To
(First_Tag_Component
(T
), Loc
))));
4285 -- Otherwise Tag_Id is not used
4291 -- Save the Prev and Next fields on .NET/JVM. This is not needed on non
4292 -- VM targets since the fields are not part of the object.
4294 if VM_Target
/= No_VM
4295 and then Is_Controlled
(T
)
4297 Prev_Id
:= Make_Temporary
(Loc
, 'P');
4298 Next_Id
:= Make_Temporary
(Loc
, 'N');
4301 -- Pnn : Root_Controlled_Ptr := Root_Controlled (L).Prev;
4304 Make_Object_Declaration
(Loc
,
4305 Defining_Identifier
=> Prev_Id
,
4306 Object_Definition
=>
4307 New_Reference_To
(RTE
(RE_Root_Controlled_Ptr
), Loc
),
4309 Make_Selected_Component
(Loc
,
4311 Unchecked_Convert_To
4312 (RTE
(RE_Root_Controlled
), New_Copy_Tree
(L
)),
4314 Make_Identifier
(Loc
, Name_Prev
))));
4317 -- Nnn : Root_Controlled_Ptr := Root_Controlled (L).Next;
4320 Make_Object_Declaration
(Loc
,
4321 Defining_Identifier
=> Next_Id
,
4322 Object_Definition
=>
4323 New_Reference_To
(RTE
(RE_Root_Controlled_Ptr
), Loc
),
4325 Make_Selected_Component
(Loc
,
4327 Unchecked_Convert_To
4328 (RTE
(RE_Root_Controlled
), New_Copy_Tree
(L
)),
4330 Make_Identifier
(Loc
, Name_Next
))));
4333 -- If the tagged type has a full rep clause, expand the assignment into
4334 -- component-wise assignments. Mark the node as unanalyzed in order to
4335 -- generate the proper code and propagate this scenario by setting a
4336 -- flag to avoid infinite recursion.
4339 Set_Analyzed
(Asn
, False);
4340 Set_Componentwise_Assignment
(Asn
, True);
4343 Append_To
(Res
, Asn
);
4349 Make_Assignment_Statement
(Loc
,
4351 Make_Selected_Component
(Loc
,
4352 Prefix
=> Duplicate_Subexpr_No_Checks
(L
),
4354 New_Reference_To
(First_Tag_Component
(T
), Loc
)),
4355 Expression
=> New_Reference_To
(Tag_Id
, Loc
)));
4358 -- Restore the Prev and Next fields on .NET/JVM
4360 if VM_Target
/= No_VM
4361 and then Is_Controlled
(T
)
4364 -- Root_Controlled (L).Prev := Prev_Id;
4367 Make_Assignment_Statement
(Loc
,
4369 Make_Selected_Component
(Loc
,
4371 Unchecked_Convert_To
4372 (RTE
(RE_Root_Controlled
), New_Copy_Tree
(L
)),
4374 Make_Identifier
(Loc
, Name_Prev
)),
4375 Expression
=> New_Reference_To
(Prev_Id
, Loc
)));
4378 -- Root_Controlled (L).Next := Next_Id;
4381 Make_Assignment_Statement
(Loc
,
4383 Make_Selected_Component
(Loc
,
4385 Unchecked_Convert_To
4386 (RTE
(RE_Root_Controlled
), New_Copy_Tree
(L
)),
4387 Selector_Name
=> Make_Identifier
(Loc
, Name_Next
)),
4388 Expression
=> New_Reference_To
(Next_Id
, Loc
)));
4391 -- Adjust the target after the assignment when controlled (not in the
4392 -- init proc since it is an initialization more than an assignment).
4397 (Obj_Ref
=> Duplicate_Subexpr_Move_Checks
(L
),
4405 -- Could use comment here ???
4407 when RE_Not_Available
=>
4409 end Make_Tag_Ctrl_Assignment
;