1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2011, 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 Exp_Aggr; use Exp_Aggr;
32 with Exp_Ch6; use Exp_Ch6;
33 with Exp_Ch7; use Exp_Ch7;
34 with Exp_Ch11; use Exp_Ch11;
35 with Exp_Dbug; use Exp_Dbug;
36 with Exp_Pakd; use Exp_Pakd;
37 with Exp_Tss; use Exp_Tss;
38 with Exp_Util; use Exp_Util;
39 with Namet; use Namet;
40 with Nlists; use Nlists;
41 with Nmake; use Nmake;
43 with Restrict; use Restrict;
44 with Rident; use Rident;
45 with Rtsfind; use Rtsfind;
46 with Sinfo; use Sinfo;
48 with Sem_Aux; use Sem_Aux;
49 with Sem_Ch3; use Sem_Ch3;
50 with Sem_Ch8; use Sem_Ch8;
51 with Sem_Ch13; use Sem_Ch13;
52 with Sem_Eval; use Sem_Eval;
53 with Sem_Res; use Sem_Res;
54 with Sem_Util; use Sem_Util;
55 with Snames; use Snames;
56 with Stand; use Stand;
57 with Stringt; use Stringt;
58 with Targparm; use Targparm;
59 with Tbuild; use Tbuild;
60 with Validsw; use Validsw;
62 package body Exp_Ch5 is
64 function Change_Of_Representation (N : Node_Id) return Boolean;
65 -- Determine if the right hand side of assignment N is a type conversion
66 -- which requires a change of representation. Called only for the array
69 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id);
70 -- N is an assignment which assigns an array value. This routine process
71 -- the various special cases and checks required for such assignments,
72 -- including change of representation. Rhs is normally simply the right
73 -- hand side of the assignment, except that if the right hand side is a
74 -- type conversion or a qualified expression, then the RHS is the actual
75 -- expression inside any such type conversions or qualifications.
77 function Expand_Assign_Array_Loop
84 Rev : Boolean) return Node_Id;
85 -- N is an assignment statement which assigns an array value. This routine
86 -- expands the assignment into a loop (or nested loops for the case of a
87 -- multi-dimensional array) to do the assignment component by component.
88 -- Larray and Rarray are the entities of the actual arrays on the left
89 -- hand and right hand sides. L_Type and R_Type are the types of these
90 -- arrays (which may not be the same, due to either sliding, or to a
91 -- change of representation case). Ndim is the number of dimensions and
92 -- the parameter Rev indicates if the loops run normally (Rev = False),
93 -- or reversed (Rev = True). The value returned is the constructed
94 -- loop statement. Auxiliary declarations are inserted before node N
95 -- using the standard Insert_Actions mechanism.
97 procedure Expand_Assign_Record (N : Node_Id);
98 -- N is an assignment of a non-tagged record value. This routine handles
99 -- the case where the assignment must be made component by component,
100 -- either because the target is not byte aligned, or there is a change
101 -- of representation, or when we have a tagged type with a representation
102 -- clause (this last case is required because holes in the tagged type
103 -- might be filled with components from child types).
105 procedure Expand_Iterator_Loop (N : Node_Id);
106 -- Expand loop over arrays and containers that uses the form "for X of C"
107 -- with an optional subtype mark, or "for Y in C".
109 procedure Expand_Predicated_Loop (N : Node_Id);
110 -- Expand for loop over predicated subtype
112 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
113 -- Generate the necessary code for controlled and tagged assignment, that
114 -- is to say, finalization of the target before, adjustment of the target
115 -- after and save and restore of the tag and finalization pointers which
116 -- are not 'part of the value' and must not be changed upon assignment. N
117 -- is the original Assignment node.
119 ------------------------------
120 -- Change_Of_Representation --
121 ------------------------------
123 function Change_Of_Representation (N : Node_Id) return Boolean is
124 Rhs : constant Node_Id := Expression (N);
127 Nkind (Rhs) = N_Type_Conversion
129 not Same_Representation (Etype (Rhs), Etype (Expression (Rhs)));
130 end Change_Of_Representation;
132 -------------------------
133 -- Expand_Assign_Array --
134 -------------------------
136 -- There are two issues here. First, do we let Gigi do a block move, or
137 -- do we expand out into a loop? Second, we need to set the two flags
138 -- Forwards_OK and Backwards_OK which show whether the block move (or
139 -- corresponding loops) can be legitimately done in a forwards (low to
140 -- high) or backwards (high to low) manner.
142 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is
143 Loc : constant Source_Ptr := Sloc (N);
145 Lhs : constant Node_Id := Name (N);
147 Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs);
148 Act_Rhs : Node_Id := Get_Referenced_Object (Rhs);
150 L_Type : constant Entity_Id :=
151 Underlying_Type (Get_Actual_Subtype (Act_Lhs));
152 R_Type : Entity_Id :=
153 Underlying_Type (Get_Actual_Subtype (Act_Rhs));
155 L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice;
156 R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice;
158 Crep : constant Boolean := Change_Of_Representation (N);
163 Ndim : constant Pos := Number_Dimensions (L_Type);
165 Loop_Required : Boolean := False;
166 -- This switch is set to True if the array move must be done using
167 -- an explicit front end generated loop.
169 procedure Apply_Dereference (Arg : Node_Id);
170 -- If the argument is an access to an array, and the assignment is
171 -- converted into a procedure call, apply explicit dereference.
173 function Has_Address_Clause (Exp : Node_Id) return Boolean;
174 -- Test if Exp is a reference to an array whose declaration has
175 -- an address clause, or it is a slice of such an array.
177 function Is_Formal_Array (Exp : Node_Id) return Boolean;
178 -- Test if Exp is a reference to an array which is either a formal
179 -- parameter or a slice of a formal parameter. These are the cases
180 -- where hidden aliasing can occur.
182 function Is_Non_Local_Array (Exp : Node_Id) return Boolean;
183 -- Determine if Exp is a reference to an array variable which is other
184 -- than an object defined in the current scope, or a slice of such
185 -- an object. Such objects can be aliased to parameters (unlike local
186 -- array references).
188 -----------------------
189 -- Apply_Dereference --
190 -----------------------
192 procedure Apply_Dereference (Arg : Node_Id) is
193 Typ : constant Entity_Id := Etype (Arg);
195 if Is_Access_Type (Typ) then
196 Rewrite (Arg, Make_Explicit_Dereference (Loc,
197 Prefix => Relocate_Node (Arg)));
198 Analyze_And_Resolve (Arg, Designated_Type (Typ));
200 end Apply_Dereference;
202 ------------------------
203 -- Has_Address_Clause --
204 ------------------------
206 function Has_Address_Clause (Exp : Node_Id) return Boolean is
209 (Is_Entity_Name (Exp) and then
210 Present (Address_Clause (Entity (Exp))))
212 (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp)));
213 end Has_Address_Clause;
215 ---------------------
216 -- Is_Formal_Array --
217 ---------------------
219 function Is_Formal_Array (Exp : Node_Id) return Boolean is
222 (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp)))
224 (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp)));
227 ------------------------
228 -- Is_Non_Local_Array --
229 ------------------------
231 function Is_Non_Local_Array (Exp : Node_Id) return Boolean is
233 return (Is_Entity_Name (Exp)
234 and then Scope (Entity (Exp)) /= Current_Scope)
235 or else (Nkind (Exp) = N_Slice
236 and then Is_Non_Local_Array (Prefix (Exp)));
237 end Is_Non_Local_Array;
239 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
241 Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs);
242 Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs);
244 Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs);
245 Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs);
247 -- Start of processing for Expand_Assign_Array
250 -- Deal with length check. Note that the length check is done with
251 -- respect to the right hand side as given, not a possible underlying
252 -- renamed object, since this would generate incorrect extra checks.
254 Apply_Length_Check (Rhs, L_Type);
256 -- We start by assuming that the move can be done in either direction,
257 -- i.e. that the two sides are completely disjoint.
259 Set_Forwards_OK (N, True);
260 Set_Backwards_OK (N, True);
262 -- Normally it is only the slice case that can lead to overlap, and
263 -- explicit checks for slices are made below. But there is one case
264 -- where the slice can be implicit and invisible to us: when we have a
265 -- one dimensional array, and either both operands are parameters, or
266 -- one is a parameter (which can be a slice passed by reference) and the
267 -- other is a non-local variable. In this case the parameter could be a
268 -- slice that overlaps with the other operand.
270 -- However, if the array subtype is a constrained first subtype in the
271 -- parameter case, then we don't have to worry about overlap, since
272 -- slice assignments aren't possible (other than for a slice denoting
275 -- Note: No overlap is possible if there is a change of representation,
276 -- so we can exclude this case.
281 ((Lhs_Formal and Rhs_Formal)
283 (Lhs_Formal and Rhs_Non_Local_Var)
285 (Rhs_Formal and Lhs_Non_Local_Var))
287 (not Is_Constrained (Etype (Lhs))
288 or else not Is_First_Subtype (Etype (Lhs)))
290 -- In the case of compiling for the Java or .NET Virtual Machine,
291 -- slices are always passed by making a copy, so we don't have to
292 -- worry about overlap. We also want to prevent generation of "<"
293 -- comparisons for array addresses, since that's a meaningless
294 -- operation on the VM.
296 and then VM_Target = No_VM
298 Set_Forwards_OK (N, False);
299 Set_Backwards_OK (N, False);
301 -- Note: the bit-packed case is not worrisome here, since if we have
302 -- a slice passed as a parameter, it is always aligned on a byte
303 -- boundary, and if there are no explicit slices, the assignment
304 -- can be performed directly.
307 -- If either operand has an address clause clear Backwards_OK and
308 -- Forwards_OK, since we cannot tell if the operands overlap. We
309 -- exclude this treatment when Rhs is an aggregate, since we know
310 -- that overlap can't occur.
312 if (Has_Address_Clause (Lhs) and then Nkind (Rhs) /= N_Aggregate)
313 or else Has_Address_Clause (Rhs)
315 Set_Forwards_OK (N, False);
316 Set_Backwards_OK (N, False);
319 -- We certainly must use a loop for change of representation and also
320 -- we use the operand of the conversion on the right hand side as the
321 -- effective right hand side (the component types must match in this
325 Act_Rhs := Get_Referenced_Object (Rhs);
326 R_Type := Get_Actual_Subtype (Act_Rhs);
327 Loop_Required := True;
329 -- We require a loop if the left side is possibly bit unaligned
331 elsif Possible_Bit_Aligned_Component (Lhs)
333 Possible_Bit_Aligned_Component (Rhs)
335 Loop_Required := True;
337 -- Arrays with controlled components are expanded into a loop to force
338 -- calls to Adjust at the component level.
340 elsif Has_Controlled_Component (L_Type) then
341 Loop_Required := True;
343 -- If object is atomic, we cannot tolerate a loop
345 elsif Is_Atomic_Object (Act_Lhs)
347 Is_Atomic_Object (Act_Rhs)
351 -- Loop is required if we have atomic components since we have to
352 -- be sure to do any accesses on an element by element basis.
354 elsif Has_Atomic_Components (L_Type)
355 or else Has_Atomic_Components (R_Type)
356 or else Is_Atomic (Component_Type (L_Type))
357 or else Is_Atomic (Component_Type (R_Type))
359 Loop_Required := True;
361 -- Case where no slice is involved
363 elsif not L_Slice and not R_Slice then
365 -- The following code deals with the case of unconstrained bit packed
366 -- arrays. The problem is that the template for such arrays contains
367 -- the bounds of the actual source level array, but the copy of an
368 -- entire array requires the bounds of the underlying array. It would
369 -- be nice if the back end could take care of this, but right now it
370 -- does not know how, so if we have such a type, then we expand out
371 -- into a loop, which is inefficient but works correctly. If we don't
372 -- do this, we get the wrong length computed for the array to be
373 -- moved. The two cases we need to worry about are:
375 -- Explicit dereference of an unconstrained packed array type as in
376 -- the following example:
379 -- type BITS is array(INTEGER range <>) of BOOLEAN;
380 -- pragma PACK(BITS);
381 -- type A is access BITS;
384 -- P1 := new BITS (1 .. 65_535);
385 -- P2 := new BITS (1 .. 65_535);
389 -- A formal parameter reference with an unconstrained bit array type
390 -- is the other case we need to worry about (here we assume the same
391 -- BITS type declared above):
393 -- procedure Write_All (File : out BITS; Contents : BITS);
395 -- File.Storage := Contents;
398 -- We expand to a loop in either of these two cases
400 -- Question for future thought. Another potentially more efficient
401 -- approach would be to create the actual subtype, and then do an
402 -- unchecked conversion to this actual subtype ???
404 Check_Unconstrained_Bit_Packed_Array : declare
406 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean;
407 -- Function to perform required test for the first case, above
408 -- (dereference of an unconstrained bit packed array).
410 -----------------------
411 -- Is_UBPA_Reference --
412 -----------------------
414 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is
415 Typ : constant Entity_Id := Underlying_Type (Etype (Opnd));
417 Des_Type : Entity_Id;
420 if Present (Packed_Array_Type (Typ))
421 and then Is_Array_Type (Packed_Array_Type (Typ))
422 and then not Is_Constrained (Packed_Array_Type (Typ))
426 elsif Nkind (Opnd) = N_Explicit_Dereference then
427 P_Type := Underlying_Type (Etype (Prefix (Opnd)));
429 if not Is_Access_Type (P_Type) then
433 Des_Type := Designated_Type (P_Type);
435 Is_Bit_Packed_Array (Des_Type)
436 and then not Is_Constrained (Des_Type);
442 end Is_UBPA_Reference;
444 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
447 if Is_UBPA_Reference (Lhs)
449 Is_UBPA_Reference (Rhs)
451 Loop_Required := True;
453 -- Here if we do not have the case of a reference to a bit packed
454 -- unconstrained array case. In this case gigi can most certainly
455 -- handle the assignment if a forwards move is allowed.
457 -- (could it handle the backwards case also???)
459 elsif Forwards_OK (N) then
462 end Check_Unconstrained_Bit_Packed_Array;
464 -- The back end can always handle the assignment if the right side is a
465 -- string literal (note that overlap is definitely impossible in this
466 -- case). If the type is packed, a string literal is always converted
467 -- into an aggregate, except in the case of a null slice, for which no
468 -- aggregate can be written. In that case, rewrite the assignment as a
469 -- null statement, a length check has already been emitted to verify
470 -- that the range of the left-hand side is empty.
472 -- Note that this code is not executed if we have an assignment of a
473 -- string literal to a non-bit aligned component of a record, a case
474 -- which cannot be handled by the backend.
476 elsif Nkind (Rhs) = N_String_Literal then
477 if String_Length (Strval (Rhs)) = 0
478 and then Is_Bit_Packed_Array (L_Type)
480 Rewrite (N, Make_Null_Statement (Loc));
486 -- If either operand is bit packed, then we need a loop, since we can't
487 -- be sure that the slice is byte aligned. Similarly, if either operand
488 -- is a possibly unaligned slice, then we need a loop (since the back
489 -- end cannot handle unaligned slices).
491 elsif Is_Bit_Packed_Array (L_Type)
492 or else Is_Bit_Packed_Array (R_Type)
493 or else Is_Possibly_Unaligned_Slice (Lhs)
494 or else Is_Possibly_Unaligned_Slice (Rhs)
496 Loop_Required := True;
498 -- If we are not bit-packed, and we have only one slice, then no overlap
499 -- is possible except in the parameter case, so we can let the back end
502 elsif not (L_Slice and R_Slice) then
503 if Forwards_OK (N) then
508 -- If the right-hand side is a string literal, introduce a temporary for
509 -- it, for use in the generated loop that will follow.
511 if Nkind (Rhs) = N_String_Literal then
513 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Rhs);
518 Make_Object_Declaration (Loc,
519 Defining_Identifier => Temp,
520 Object_Definition => New_Occurrence_Of (L_Type, Loc),
521 Expression => Relocate_Node (Rhs));
523 Insert_Action (N, Decl);
524 Rewrite (Rhs, New_Occurrence_Of (Temp, Loc));
525 R_Type := Etype (Temp);
529 -- Come here to complete the analysis
531 -- Loop_Required: Set to True if we know that a loop is required
532 -- regardless of overlap considerations.
534 -- Forwards_OK: Set to False if we already know that a forwards
535 -- move is not safe, else set to True.
537 -- Backwards_OK: Set to False if we already know that a backwards
538 -- move is not safe, else set to True
540 -- Our task at this stage is to complete the overlap analysis, which can
541 -- result in possibly setting Forwards_OK or Backwards_OK to False, and
542 -- then generating the final code, either by deciding that it is OK
543 -- after all to let Gigi handle it, or by generating appropriate code
547 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
548 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type));
550 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ);
551 Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ);
552 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ);
553 Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ);
555 Act_L_Array : Node_Id;
556 Act_R_Array : Node_Id;
562 Cresult : Compare_Result;
565 -- Get the expressions for the arrays. If we are dealing with a
566 -- private type, then convert to the underlying type. We can do
567 -- direct assignments to an array that is a private type, but we
568 -- cannot assign to elements of the array without this extra
569 -- unchecked conversion.
571 -- Note: We propagate Parent to the conversion nodes to generate
572 -- a well-formed subtree.
574 if Nkind (Act_Lhs) = N_Slice then
575 Larray := Prefix (Act_Lhs);
579 if Is_Private_Type (Etype (Larray)) then
581 Par : constant Node_Id := Parent (Larray);
585 (Underlying_Type (Etype (Larray)), Larray);
586 Set_Parent (Larray, Par);
591 if Nkind (Act_Rhs) = N_Slice then
592 Rarray := Prefix (Act_Rhs);
596 if Is_Private_Type (Etype (Rarray)) then
598 Par : constant Node_Id := Parent (Rarray);
602 (Underlying_Type (Etype (Rarray)), Rarray);
603 Set_Parent (Rarray, Par);
608 -- If both sides are slices, we must figure out whether it is safe
609 -- to do the move in one direction or the other. It is always safe
610 -- if there is a change of representation since obviously two arrays
611 -- with different representations cannot possibly overlap.
613 if (not Crep) and L_Slice and R_Slice then
614 Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
615 Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
617 -- If both left and right hand arrays are entity names, and refer
618 -- to different entities, then we know that the move is safe (the
619 -- two storage areas are completely disjoint).
621 if Is_Entity_Name (Act_L_Array)
622 and then Is_Entity_Name (Act_R_Array)
623 and then Entity (Act_L_Array) /= Entity (Act_R_Array)
627 -- Otherwise, we assume the worst, which is that the two arrays
628 -- are the same array. There is no need to check if we know that
629 -- is the case, because if we don't know it, we still have to
632 -- Generally if the same array is involved, then we have an
633 -- overlapping case. We will have to really assume the worst (i.e.
634 -- set neither of the OK flags) unless we can determine the lower
635 -- or upper bounds at compile time and compare them.
640 (Left_Lo, Right_Lo, Assume_Valid => True);
642 if Cresult = Unknown then
645 (Left_Hi, Right_Hi, Assume_Valid => True);
649 when LT | LE | EQ => Set_Backwards_OK (N, False);
650 when GT | GE => Set_Forwards_OK (N, False);
651 when NE | Unknown => Set_Backwards_OK (N, False);
652 Set_Forwards_OK (N, False);
657 -- If after that analysis Loop_Required is False, meaning that we
658 -- have not discovered some non-overlap reason for requiring a loop,
659 -- then the outcome depends on the capabilities of the back end.
661 if not Loop_Required then
663 -- The GCC back end can deal with all cases of overlap by falling
664 -- back to memmove if it cannot use a more efficient approach.
666 if VM_Target = No_VM and not AAMP_On_Target then
669 -- Assume other back ends can handle it if Forwards_OK is set
671 elsif Forwards_OK (N) then
674 -- If Forwards_OK is not set, the back end will need something
675 -- like memmove to handle the move. For now, this processing is
676 -- activated using the .s debug flag (-gnatd.s).
678 elsif Debug_Flag_Dot_S then
683 -- At this stage we have to generate an explicit loop, and we have
684 -- the following cases:
686 -- Forwards_OK = True
688 -- Rnn : right_index := right_index'First;
689 -- for Lnn in left-index loop
690 -- left (Lnn) := right (Rnn);
691 -- Rnn := right_index'Succ (Rnn);
694 -- Note: the above code MUST be analyzed with checks off, because
695 -- otherwise the Succ could overflow. But in any case this is more
698 -- Forwards_OK = False, Backwards_OK = True
700 -- Rnn : right_index := right_index'Last;
701 -- for Lnn in reverse left-index loop
702 -- left (Lnn) := right (Rnn);
703 -- Rnn := right_index'Pred (Rnn);
706 -- Note: the above code MUST be analyzed with checks off, because
707 -- otherwise the Pred could overflow. But in any case this is more
710 -- Forwards_OK = Backwards_OK = False
712 -- This only happens if we have the same array on each side. It is
713 -- possible to create situations using overlays that violate this,
714 -- but we simply do not promise to get this "right" in this case.
716 -- There are two possible subcases. If the No_Implicit_Conditionals
717 -- restriction is set, then we generate the following code:
720 -- T : constant <operand-type> := rhs;
725 -- If implicit conditionals are permitted, then we generate:
727 -- if Left_Lo <= Right_Lo then
728 -- <code for Forwards_OK = True above>
730 -- <code for Backwards_OK = True above>
733 -- In order to detect possible aliasing, we examine the renamed
734 -- expression when the source or target is a renaming. However,
735 -- the renaming may be intended to capture an address that may be
736 -- affected by subsequent code, and therefore we must recover
737 -- the actual entity for the expansion that follows, not the
738 -- object it renames. In particular, if source or target designate
739 -- a portion of a dynamically allocated object, the pointer to it
740 -- may be reassigned but the renaming preserves the proper location.
742 if Is_Entity_Name (Rhs)
744 Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration
745 and then Nkind (Act_Rhs) = N_Slice
750 if Is_Entity_Name (Lhs)
752 Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration
753 and then Nkind (Act_Lhs) = N_Slice
758 -- Cases where either Forwards_OK or Backwards_OK is true
760 if Forwards_OK (N) or else Backwards_OK (N) then
761 if Needs_Finalization (Component_Type (L_Type))
762 and then Base_Type (L_Type) = Base_Type (R_Type)
764 and then not No_Ctrl_Actions (N)
767 Proc : constant Entity_Id :=
768 TSS (Base_Type (L_Type), TSS_Slice_Assign);
772 Apply_Dereference (Larray);
773 Apply_Dereference (Rarray);
774 Actuals := New_List (
775 Duplicate_Subexpr (Larray, Name_Req => True),
776 Duplicate_Subexpr (Rarray, Name_Req => True),
777 Duplicate_Subexpr (Left_Lo, Name_Req => True),
778 Duplicate_Subexpr (Left_Hi, Name_Req => True),
779 Duplicate_Subexpr (Right_Lo, Name_Req => True),
780 Duplicate_Subexpr (Right_Hi, Name_Req => True));
784 Boolean_Literals (not Forwards_OK (N)), Loc));
787 Make_Procedure_Call_Statement (Loc,
788 Name => New_Reference_To (Proc, Loc),
789 Parameter_Associations => Actuals));
794 Expand_Assign_Array_Loop
795 (N, Larray, Rarray, L_Type, R_Type, Ndim,
796 Rev => not Forwards_OK (N)));
799 -- Case of both are false with No_Implicit_Conditionals
801 elsif Restriction_Active (No_Implicit_Conditionals) then
803 T : constant Entity_Id :=
804 Make_Defining_Identifier (Loc, Chars => Name_T);
808 Make_Block_Statement (Loc,
809 Declarations => New_List (
810 Make_Object_Declaration (Loc,
811 Defining_Identifier => T,
812 Constant_Present => True,
814 New_Occurrence_Of (Etype (Rhs), Loc),
815 Expression => Relocate_Node (Rhs))),
817 Handled_Statement_Sequence =>
818 Make_Handled_Sequence_Of_Statements (Loc,
819 Statements => New_List (
820 Make_Assignment_Statement (Loc,
821 Name => Relocate_Node (Lhs),
822 Expression => New_Occurrence_Of (T, Loc))))));
825 -- Case of both are false with implicit conditionals allowed
828 -- Before we generate this code, we must ensure that the left and
829 -- right side array types are defined. They may be itypes, and we
830 -- cannot let them be defined inside the if, since the first use
831 -- in the then may not be executed.
833 Ensure_Defined (L_Type, N);
834 Ensure_Defined (R_Type, N);
836 -- We normally compare addresses to find out which way round to
837 -- do the loop, since this is reliable, and handles the cases of
838 -- parameters, conversions etc. But we can't do that in the bit
839 -- packed case or the VM case, because addresses don't work there.
841 if not Is_Bit_Packed_Array (L_Type) and then VM_Target = No_VM then
845 Unchecked_Convert_To (RTE (RE_Integer_Address),
846 Make_Attribute_Reference (Loc,
848 Make_Indexed_Component (Loc,
850 Duplicate_Subexpr_Move_Checks (Larray, True),
851 Expressions => New_List (
852 Make_Attribute_Reference (Loc,
856 Attribute_Name => Name_First))),
857 Attribute_Name => Name_Address)),
860 Unchecked_Convert_To (RTE (RE_Integer_Address),
861 Make_Attribute_Reference (Loc,
863 Make_Indexed_Component (Loc,
865 Duplicate_Subexpr_Move_Checks (Rarray, True),
866 Expressions => New_List (
867 Make_Attribute_Reference (Loc,
871 Attribute_Name => Name_First))),
872 Attribute_Name => Name_Address)));
874 -- For the bit packed and VM cases we use the bounds. That's OK,
875 -- because we don't have to worry about parameters, since they
876 -- cannot cause overlap. Perhaps we should worry about weird slice
882 Cleft_Lo := New_Copy_Tree (Left_Lo);
883 Cright_Lo := New_Copy_Tree (Right_Lo);
885 -- If the types do not match we add an implicit conversion
886 -- here to ensure proper match
888 if Etype (Left_Lo) /= Etype (Right_Lo) then
890 Unchecked_Convert_To (Etype (Left_Lo), Cright_Lo);
893 -- Reset the Analyzed flag, because the bounds of the index
894 -- type itself may be universal, and must must be reanalyzed
895 -- to acquire the proper type for the back end.
897 Set_Analyzed (Cleft_Lo, False);
898 Set_Analyzed (Cright_Lo, False);
902 Left_Opnd => Cleft_Lo,
903 Right_Opnd => Cright_Lo);
906 if Needs_Finalization (Component_Type (L_Type))
907 and then Base_Type (L_Type) = Base_Type (R_Type)
909 and then not No_Ctrl_Actions (N)
912 -- Call TSS procedure for array assignment, passing the
913 -- explicit bounds of right and left hand sides.
916 Proc : constant Entity_Id :=
917 TSS (Base_Type (L_Type), TSS_Slice_Assign);
921 Apply_Dereference (Larray);
922 Apply_Dereference (Rarray);
923 Actuals := New_List (
924 Duplicate_Subexpr (Larray, Name_Req => True),
925 Duplicate_Subexpr (Rarray, Name_Req => True),
926 Duplicate_Subexpr (Left_Lo, Name_Req => True),
927 Duplicate_Subexpr (Left_Hi, Name_Req => True),
928 Duplicate_Subexpr (Right_Lo, Name_Req => True),
929 Duplicate_Subexpr (Right_Hi, Name_Req => True));
933 Right_Opnd => Condition));
936 Make_Procedure_Call_Statement (Loc,
937 Name => New_Reference_To (Proc, Loc),
938 Parameter_Associations => Actuals));
943 Make_Implicit_If_Statement (N,
944 Condition => Condition,
946 Then_Statements => New_List (
947 Expand_Assign_Array_Loop
948 (N, Larray, Rarray, L_Type, R_Type, Ndim,
951 Else_Statements => New_List (
952 Expand_Assign_Array_Loop
953 (N, Larray, Rarray, L_Type, R_Type, Ndim,
958 Analyze (N, Suppress => All_Checks);
962 when RE_Not_Available =>
964 end Expand_Assign_Array;
966 ------------------------------
967 -- Expand_Assign_Array_Loop --
968 ------------------------------
970 -- The following is an example of the loop generated for the case of a
971 -- two-dimensional array:
976 -- for L1b in 1 .. 100 loop
980 -- for L3b in 1 .. 100 loop
981 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
982 -- R4b := Tm1X2'succ(R4b);
985 -- R2b := Tm1X1'succ(R2b);
989 -- Here Rev is False, and Tm1Xn are the subscript types for the right hand
990 -- side. The declarations of R2b and R4b are inserted before the original
991 -- assignment statement.
993 function Expand_Assign_Array_Loop
1000 Rev : Boolean) return Node_Id
1002 Loc : constant Source_Ptr := Sloc (N);
1004 Lnn : array (1 .. Ndim) of Entity_Id;
1005 Rnn : array (1 .. Ndim) of Entity_Id;
1006 -- Entities used as subscripts on left and right sides
1008 L_Index_Type : array (1 .. Ndim) of Entity_Id;
1009 R_Index_Type : array (1 .. Ndim) of Entity_Id;
1010 -- Left and right index types
1017 function Build_Step (J : Nat) return Node_Id;
1018 -- The increment step for the index of the right-hand side is written
1019 -- as an attribute reference (Succ or Pred). This function returns
1020 -- the corresponding node, which is placed at the end of the loop body.
1026 function Build_Step (J : Nat) return Node_Id is
1038 Make_Assignment_Statement (Loc,
1039 Name => New_Occurrence_Of (Rnn (J), Loc),
1041 Make_Attribute_Reference (Loc,
1043 New_Occurrence_Of (R_Index_Type (J), Loc),
1044 Attribute_Name => S_Or_P,
1045 Expressions => New_List (
1046 New_Occurrence_Of (Rnn (J), Loc))));
1048 -- Note that on the last iteration of the loop, the index is increased
1049 -- (or decreased) past the corresponding bound. This is consistent with
1050 -- the C semantics of the back-end, where such an off-by-one value on a
1051 -- dead index variable is OK. However, in CodePeer mode this leads to
1052 -- spurious warnings, and thus we place a guard around the attribute
1053 -- reference. For obvious reasons we only do this for CodePeer.
1055 if CodePeer_Mode then
1057 Make_If_Statement (Loc,
1060 Left_Opnd => New_Occurrence_Of (Lnn (J), Loc),
1062 Make_Attribute_Reference (Loc,
1063 Prefix => New_Occurrence_Of (L_Index_Type (J), Loc),
1064 Attribute_Name => Lim)),
1065 Then_Statements => New_List (Step));
1071 -- Start of processing for Expand_Assign_Array_Loop
1075 F_Or_L := Name_Last;
1076 S_Or_P := Name_Pred;
1078 F_Or_L := Name_First;
1079 S_Or_P := Name_Succ;
1082 -- Setup index types and subscript entities
1089 L_Index := First_Index (L_Type);
1090 R_Index := First_Index (R_Type);
1092 for J in 1 .. Ndim loop
1093 Lnn (J) := Make_Temporary (Loc, 'L');
1094 Rnn (J) := Make_Temporary (Loc, 'R');
1096 L_Index_Type (J) := Etype (L_Index);
1097 R_Index_Type (J) := Etype (R_Index);
1099 Next_Index (L_Index);
1100 Next_Index (R_Index);
1104 -- Now construct the assignment statement
1107 ExprL : constant List_Id := New_List;
1108 ExprR : constant List_Id := New_List;
1111 for J in 1 .. Ndim loop
1112 Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc));
1113 Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc));
1117 Make_Assignment_Statement (Loc,
1119 Make_Indexed_Component (Loc,
1120 Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
1121 Expressions => ExprL),
1123 Make_Indexed_Component (Loc,
1124 Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
1125 Expressions => ExprR));
1127 -- We set assignment OK, since there are some cases, e.g. in object
1128 -- declarations, where we are actually assigning into a constant.
1129 -- If there really is an illegality, it was caught long before now,
1130 -- and was flagged when the original assignment was analyzed.
1132 Set_Assignment_OK (Name (Assign));
1134 -- Propagate the No_Ctrl_Actions flag to individual assignments
1136 Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
1139 -- Now construct the loop from the inside out, with the last subscript
1140 -- varying most rapidly. Note that Assign is first the raw assignment
1141 -- statement, and then subsequently the loop that wraps it up.
1143 for J in reverse 1 .. Ndim loop
1145 Make_Block_Statement (Loc,
1146 Declarations => New_List (
1147 Make_Object_Declaration (Loc,
1148 Defining_Identifier => Rnn (J),
1149 Object_Definition =>
1150 New_Occurrence_Of (R_Index_Type (J), Loc),
1152 Make_Attribute_Reference (Loc,
1153 Prefix => New_Occurrence_Of (R_Index_Type (J), Loc),
1154 Attribute_Name => F_Or_L))),
1156 Handled_Statement_Sequence =>
1157 Make_Handled_Sequence_Of_Statements (Loc,
1158 Statements => New_List (
1159 Make_Implicit_Loop_Statement (N,
1161 Make_Iteration_Scheme (Loc,
1162 Loop_Parameter_Specification =>
1163 Make_Loop_Parameter_Specification (Loc,
1164 Defining_Identifier => Lnn (J),
1165 Reverse_Present => Rev,
1166 Discrete_Subtype_Definition =>
1167 New_Reference_To (L_Index_Type (J), Loc))),
1169 Statements => New_List (Assign, Build_Step (J))))));
1173 end Expand_Assign_Array_Loop;
1175 --------------------------
1176 -- Expand_Assign_Record --
1177 --------------------------
1179 procedure Expand_Assign_Record (N : Node_Id) is
1180 Lhs : constant Node_Id := Name (N);
1181 Rhs : Node_Id := Expression (N);
1182 L_Typ : constant Entity_Id := Base_Type (Etype (Lhs));
1185 -- If change of representation, then extract the real right hand side
1186 -- from the type conversion, and proceed with component-wise assignment,
1187 -- since the two types are not the same as far as the back end is
1190 if Change_Of_Representation (N) then
1191 Rhs := Expression (Rhs);
1193 -- If this may be a case of a large bit aligned component, then proceed
1194 -- with component-wise assignment, to avoid possible clobbering of other
1195 -- components sharing bits in the first or last byte of the component to
1198 elsif Possible_Bit_Aligned_Component (Lhs)
1200 Possible_Bit_Aligned_Component (Rhs)
1204 -- If we have a tagged type that has a complete record representation
1205 -- clause, we must do we must do component-wise assignments, since child
1206 -- types may have used gaps for their components, and we might be
1207 -- dealing with a view conversion.
1209 elsif Is_Fully_Repped_Tagged_Type (L_Typ) then
1212 -- If neither condition met, then nothing special to do, the back end
1213 -- can handle assignment of the entire component as a single entity.
1219 -- At this stage we know that we must do a component wise assignment
1222 Loc : constant Source_Ptr := Sloc (N);
1223 R_Typ : constant Entity_Id := Base_Type (Etype (Rhs));
1224 Decl : constant Node_Id := Declaration_Node (R_Typ);
1228 function Find_Component
1230 Comp : Entity_Id) return Entity_Id;
1231 -- Find the component with the given name in the underlying record
1232 -- declaration for Typ. We need to use the actual entity because the
1233 -- type may be private and resolution by identifier alone would fail.
1235 function Make_Component_List_Assign
1237 U_U : Boolean := False) return List_Id;
1238 -- Returns a sequence of statements to assign the components that
1239 -- are referenced in the given component list. The flag U_U is
1240 -- used to force the usage of the inferred value of the variant
1241 -- part expression as the switch for the generated case statement.
1243 function Make_Field_Assign
1245 U_U : Boolean := False) return Node_Id;
1246 -- Given C, the entity for a discriminant or component, build an
1247 -- assignment for the corresponding field values. The flag U_U
1248 -- signals the presence of an Unchecked_Union and forces the usage
1249 -- of the inferred discriminant value of C as the right hand side
1250 -- of the assignment.
1252 function Make_Field_Assigns (CI : List_Id) return List_Id;
1253 -- Given CI, a component items list, construct series of statements
1254 -- for fieldwise assignment of the corresponding components.
1256 --------------------
1257 -- Find_Component --
1258 --------------------
1260 function Find_Component
1262 Comp : Entity_Id) return Entity_Id
1264 Utyp : constant Entity_Id := Underlying_Type (Typ);
1268 C := First_Entity (Utyp);
1269 while Present (C) loop
1270 if Chars (C) = Chars (Comp) then
1277 raise Program_Error;
1280 --------------------------------
1281 -- Make_Component_List_Assign --
1282 --------------------------------
1284 function Make_Component_List_Assign
1286 U_U : Boolean := False) return List_Id
1288 CI : constant List_Id := Component_Items (CL);
1289 VP : constant Node_Id := Variant_Part (CL);
1299 Result := Make_Field_Assigns (CI);
1301 if Present (VP) then
1302 V := First_Non_Pragma (Variants (VP));
1304 while Present (V) loop
1306 DC := First (Discrete_Choices (V));
1307 while Present (DC) loop
1308 Append_To (DCH, New_Copy_Tree (DC));
1313 Make_Case_Statement_Alternative (Loc,
1314 Discrete_Choices => DCH,
1316 Make_Component_List_Assign (Component_List (V))));
1317 Next_Non_Pragma (V);
1320 -- If we have an Unchecked_Union, use the value of the inferred
1321 -- discriminant of the variant part expression as the switch
1322 -- for the case statement. The case statement may later be
1327 New_Copy (Get_Discriminant_Value (
1330 Discriminant_Constraint (Etype (Rhs))));
1333 Make_Selected_Component (Loc,
1334 Prefix => Duplicate_Subexpr (Rhs),
1336 Make_Identifier (Loc, Chars (Name (VP))));
1340 Make_Case_Statement (Loc,
1342 Alternatives => Alts));
1346 end Make_Component_List_Assign;
1348 -----------------------
1349 -- Make_Field_Assign --
1350 -----------------------
1352 function Make_Field_Assign
1354 U_U : Boolean := False) return Node_Id
1360 -- In the case of an Unchecked_Union, use the discriminant
1361 -- constraint value as on the right hand side of the assignment.
1365 New_Copy (Get_Discriminant_Value (C,
1367 Discriminant_Constraint (Etype (Rhs))));
1370 Make_Selected_Component (Loc,
1371 Prefix => Duplicate_Subexpr (Rhs),
1372 Selector_Name => New_Occurrence_Of (C, Loc));
1376 Make_Assignment_Statement (Loc,
1378 Make_Selected_Component (Loc,
1379 Prefix => Duplicate_Subexpr (Lhs),
1381 New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
1382 Expression => Expr);
1384 -- Set Assignment_OK, so discriminants can be assigned
1386 Set_Assignment_OK (Name (A), True);
1388 if Componentwise_Assignment (N)
1389 and then Nkind (Name (A)) = N_Selected_Component
1390 and then Chars (Selector_Name (Name (A))) = Name_uParent
1392 Set_Componentwise_Assignment (A);
1396 end Make_Field_Assign;
1398 ------------------------
1399 -- Make_Field_Assigns --
1400 ------------------------
1402 function Make_Field_Assigns (CI : List_Id) return List_Id is
1410 while Present (Item) loop
1412 -- Look for components, but exclude _tag field assignment if
1413 -- the special Componentwise_Assignment flag is set.
1415 if Nkind (Item) = N_Component_Declaration
1416 and then not (Is_Tag (Defining_Identifier (Item))
1417 and then Componentwise_Assignment (N))
1420 (Result, Make_Field_Assign (Defining_Identifier (Item)));
1427 end Make_Field_Assigns;
1429 -- Start of processing for Expand_Assign_Record
1432 -- Note that we use the base types for this processing. This results
1433 -- in some extra work in the constrained case, but the change of
1434 -- representation case is so unusual that it is not worth the effort.
1436 -- First copy the discriminants. This is done unconditionally. It
1437 -- is required in the unconstrained left side case, and also in the
1438 -- case where this assignment was constructed during the expansion
1439 -- of a type conversion (since initialization of discriminants is
1440 -- suppressed in this case). It is unnecessary but harmless in
1443 if Has_Discriminants (L_Typ) then
1444 F := First_Discriminant (R_Typ);
1445 while Present (F) loop
1447 -- If we are expanding the initialization of a derived record
1448 -- that constrains or renames discriminants of the parent, we
1449 -- must use the corresponding discriminant in the parent.
1456 and then Present (Corresponding_Discriminant (F))
1458 CF := Corresponding_Discriminant (F);
1463 if Is_Unchecked_Union (Base_Type (R_Typ)) then
1465 -- Within an initialization procedure this is the
1466 -- assignment to an unchecked union component, in which
1467 -- case there is no discriminant to initialize.
1469 if Inside_Init_Proc then
1473 -- The assignment is part of a conversion from a
1474 -- derived unchecked union type with an inferable
1475 -- discriminant, to a parent type.
1477 Insert_Action (N, Make_Field_Assign (CF, True));
1481 Insert_Action (N, Make_Field_Assign (CF));
1484 Next_Discriminant (F);
1489 -- We know the underlying type is a record, but its current view
1490 -- may be private. We must retrieve the usable record declaration.
1492 if Nkind_In (Decl, N_Private_Type_Declaration,
1493 N_Private_Extension_Declaration)
1494 and then Present (Full_View (R_Typ))
1496 RDef := Type_Definition (Declaration_Node (Full_View (R_Typ)));
1498 RDef := Type_Definition (Decl);
1501 if Nkind (RDef) = N_Derived_Type_Definition then
1502 RDef := Record_Extension_Part (RDef);
1505 if Nkind (RDef) = N_Record_Definition
1506 and then Present (Component_List (RDef))
1508 if Is_Unchecked_Union (R_Typ) then
1510 Make_Component_List_Assign (Component_List (RDef), True));
1513 (N, Make_Component_List_Assign (Component_List (RDef)));
1516 Rewrite (N, Make_Null_Statement (Loc));
1519 end Expand_Assign_Record;
1521 -----------------------------------
1522 -- Expand_N_Assignment_Statement --
1523 -----------------------------------
1525 -- This procedure implements various cases where an assignment statement
1526 -- cannot just be passed on to the back end in untransformed state.
1528 procedure Expand_N_Assignment_Statement (N : Node_Id) is
1529 Loc : constant Source_Ptr := Sloc (N);
1530 Crep : constant Boolean := Change_Of_Representation (N);
1531 Lhs : constant Node_Id := Name (N);
1532 Rhs : constant Node_Id := Expression (N);
1533 Typ : constant Entity_Id := Underlying_Type (Etype (Lhs));
1537 -- Special case to check right away, if the Componentwise_Assignment
1538 -- flag is set, this is a reanalysis from the expansion of the primitive
1539 -- assignment procedure for a tagged type, and all we need to do is to
1540 -- expand to assignment of components, because otherwise, we would get
1541 -- infinite recursion (since this looks like a tagged assignment which
1542 -- would normally try to *call* the primitive assignment procedure).
1544 if Componentwise_Assignment (N) then
1545 Expand_Assign_Record (N);
1549 -- Defend against invalid subscripts on left side if we are in standard
1550 -- validity checking mode. No need to do this if we are checking all
1553 -- Note that we do this right away, because there are some early return
1554 -- paths in this procedure, and this is required on all paths.
1556 if Validity_Checks_On
1557 and then Validity_Check_Default
1558 and then not Validity_Check_Subscripts
1560 Check_Valid_Lvalue_Subscripts (Lhs);
1563 -- Ada 2005 (AI-327): Handle assignment to priority of protected object
1565 -- Rewrite an assignment to X'Priority into a run-time call
1567 -- For example: X'Priority := New_Prio_Expr;
1568 -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr);
1570 -- Note that although X'Priority is notionally an object, it is quite
1571 -- deliberately not defined as an aliased object in the RM. This means
1572 -- that it works fine to rewrite it as a call, without having to worry
1573 -- about complications that would other arise from X'Priority'Access,
1574 -- which is illegal, because of the lack of aliasing.
1576 if Ada_Version >= Ada_2005 then
1579 Conctyp : Entity_Id;
1582 RT_Subprg_Name : Node_Id;
1585 -- Handle chains of renamings
1588 while Nkind (Ent) in N_Has_Entity
1589 and then Present (Entity (Ent))
1590 and then Present (Renamed_Object (Entity (Ent)))
1592 Ent := Renamed_Object (Entity (Ent));
1595 -- The attribute Priority applied to protected objects has been
1596 -- previously expanded into a call to the Get_Ceiling run-time
1599 if Nkind (Ent) = N_Function_Call
1600 and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling)
1602 Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling))
1604 -- Look for the enclosing concurrent type
1606 Conctyp := Current_Scope;
1607 while not Is_Concurrent_Type (Conctyp) loop
1608 Conctyp := Scope (Conctyp);
1611 pragma Assert (Is_Protected_Type (Conctyp));
1613 -- Generate the first actual of the call
1615 Subprg := Current_Scope;
1616 while not Present (Protected_Body_Subprogram (Subprg)) loop
1617 Subprg := Scope (Subprg);
1620 -- Select the appropriate run-time call
1622 if Number_Entries (Conctyp) = 0 then
1624 New_Reference_To (RTE (RE_Set_Ceiling), Loc);
1627 New_Reference_To (RTE (RO_PE_Set_Ceiling), Loc);
1631 Make_Procedure_Call_Statement (Loc,
1632 Name => RT_Subprg_Name,
1633 Parameter_Associations => New_List (
1634 New_Copy_Tree (First (Parameter_Associations (Ent))),
1635 Relocate_Node (Expression (N))));
1644 -- Deal with assignment checks unless suppressed
1646 if not Suppress_Assignment_Checks (N) then
1648 -- First deal with generation of range check if required
1650 if Do_Range_Check (Rhs) then
1651 Set_Do_Range_Check (Rhs, False);
1652 Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed);
1655 -- Then generate predicate check if required
1657 Apply_Predicate_Check (Rhs, Typ);
1660 -- Check for a special case where a high level transformation is
1661 -- required. If we have either of:
1666 -- where P is a reference to a bit packed array, then we have to unwind
1667 -- the assignment. The exact meaning of being a reference to a bit
1668 -- packed array is as follows:
1670 -- An indexed component whose prefix is a bit packed array is a
1671 -- reference to a bit packed array.
1673 -- An indexed component or selected component whose prefix is a
1674 -- reference to a bit packed array is itself a reference ot a
1675 -- bit packed array.
1677 -- The required transformation is
1679 -- Tnn : prefix_type := P;
1680 -- Tnn.field := rhs;
1685 -- Tnn : prefix_type := P;
1686 -- Tnn (subscr) := rhs;
1689 -- Since P is going to be evaluated more than once, any subscripts
1690 -- in P must have their evaluation forced.
1692 if Nkind_In (Lhs, N_Indexed_Component, N_Selected_Component)
1693 and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs))
1696 BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs));
1697 BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr);
1698 Tnn : constant Entity_Id :=
1699 Make_Temporary (Loc, 'T', BPAR_Expr);
1702 -- Insert the post assignment first, because we want to copy the
1703 -- BPAR_Expr tree before it gets analyzed in the context of the
1704 -- pre assignment. Note that we do not analyze the post assignment
1705 -- yet (we cannot till we have completed the analysis of the pre
1706 -- assignment). As usual, the analysis of this post assignment
1707 -- will happen on its own when we "run into" it after finishing
1708 -- the current assignment.
1711 Make_Assignment_Statement (Loc,
1712 Name => New_Copy_Tree (BPAR_Expr),
1713 Expression => New_Occurrence_Of (Tnn, Loc)));
1715 -- At this stage BPAR_Expr is a reference to a bit packed array
1716 -- where the reference was not expanded in the original tree,
1717 -- since it was on the left side of an assignment. But in the
1718 -- pre-assignment statement (the object definition), BPAR_Expr
1719 -- will end up on the right hand side, and must be reexpanded. To
1720 -- achieve this, we reset the analyzed flag of all selected and
1721 -- indexed components down to the actual indexed component for
1722 -- the packed array.
1726 Set_Analyzed (Exp, False);
1729 (Exp, N_Selected_Component, N_Indexed_Component)
1731 Exp := Prefix (Exp);
1737 -- Now we can insert and analyze the pre-assignment
1739 -- If the right-hand side requires a transient scope, it has
1740 -- already been placed on the stack. However, the declaration is
1741 -- inserted in the tree outside of this scope, and must reflect
1742 -- the proper scope for its variable. This awkward bit is forced
1743 -- by the stricter scope discipline imposed by GCC 2.97.
1746 Uses_Transient_Scope : constant Boolean :=
1748 and then N = Node_To_Be_Wrapped;
1751 if Uses_Transient_Scope then
1752 Push_Scope (Scope (Current_Scope));
1755 Insert_Before_And_Analyze (N,
1756 Make_Object_Declaration (Loc,
1757 Defining_Identifier => Tnn,
1758 Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc),
1759 Expression => BPAR_Expr));
1761 if Uses_Transient_Scope then
1766 -- Now fix up the original assignment and continue processing
1768 Rewrite (Prefix (Lhs),
1769 New_Occurrence_Of (Tnn, Loc));
1771 -- We do not need to reanalyze that assignment, and we do not need
1772 -- to worry about references to the temporary, but we do need to
1773 -- make sure that the temporary is not marked as a true constant
1774 -- since we now have a generated assignment to it!
1776 Set_Is_True_Constant (Tnn, False);
1780 -- When we have the appropriate type of aggregate in the expression (it
1781 -- has been determined during analysis of the aggregate by setting the
1782 -- delay flag), let's perform in place assignment and thus avoid
1783 -- creating a temporary.
1785 if Is_Delayed_Aggregate (Rhs) then
1786 Convert_Aggr_In_Assignment (N);
1787 Rewrite (N, Make_Null_Statement (Loc));
1792 -- Apply discriminant check if required. If Lhs is an access type to a
1793 -- designated type with discriminants, we must always check.
1795 if Has_Discriminants (Etype (Lhs)) then
1797 -- Skip discriminant check if change of representation. Will be
1798 -- done when the change of representation is expanded out.
1801 Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs);
1804 -- If the type is private without discriminants, and the full type
1805 -- has discriminants (necessarily with defaults) a check may still be
1806 -- necessary if the Lhs is aliased. The private discriminants must be
1807 -- visible to build the discriminant constraints.
1809 -- Only an explicit dereference that comes from source indicates
1810 -- aliasing. Access to formals of protected operations and entries
1811 -- create dereferences but are not semantic aliasings.
1813 elsif Is_Private_Type (Etype (Lhs))
1814 and then Has_Discriminants (Typ)
1815 and then Nkind (Lhs) = N_Explicit_Dereference
1816 and then Comes_From_Source (Lhs)
1819 Lt : constant Entity_Id := Etype (Lhs);
1820 Ubt : Entity_Id := Base_Type (Typ);
1823 -- In the case of an expander-generated record subtype whose base
1824 -- type still appears private, Typ will have been set to that
1825 -- private type rather than the underlying record type (because
1826 -- Underlying type will have returned the record subtype), so it's
1827 -- necessary to apply Underlying_Type again to the base type to
1828 -- get the record type we need for the discriminant check. Such
1829 -- subtypes can be created for assignments in certain cases, such
1830 -- as within an instantiation passed this kind of private type.
1831 -- It would be good to avoid this special test, but making changes
1832 -- to prevent this odd form of record subtype seems difficult. ???
1834 if Is_Private_Type (Ubt) then
1835 Ubt := Underlying_Type (Ubt);
1838 Set_Etype (Lhs, Ubt);
1839 Rewrite (Rhs, OK_Convert_To (Base_Type (Ubt), Rhs));
1840 Apply_Discriminant_Check (Rhs, Ubt, Lhs);
1841 Set_Etype (Lhs, Lt);
1844 -- If the Lhs has a private type with unknown discriminants, it
1845 -- may have a full view with discriminants, but those are nameable
1846 -- only in the underlying type, so convert the Rhs to it before
1847 -- potential checking.
1849 elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs)))
1850 and then Has_Discriminants (Typ)
1852 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1853 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1855 -- In the access type case, we need the same discriminant check, and
1856 -- also range checks if we have an access to constrained array.
1858 elsif Is_Access_Type (Etype (Lhs))
1859 and then Is_Constrained (Designated_Type (Etype (Lhs)))
1861 if Has_Discriminants (Designated_Type (Etype (Lhs))) then
1863 -- Skip discriminant check if change of representation. Will be
1864 -- done when the change of representation is expanded out.
1867 Apply_Discriminant_Check (Rhs, Etype (Lhs));
1870 elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then
1871 Apply_Range_Check (Rhs, Etype (Lhs));
1873 if Is_Constrained (Etype (Lhs)) then
1874 Apply_Length_Check (Rhs, Etype (Lhs));
1877 if Nkind (Rhs) = N_Allocator then
1879 Target_Typ : constant Entity_Id := Etype (Expression (Rhs));
1880 C_Es : Check_Result;
1887 Etype (Designated_Type (Etype (Lhs))));
1899 -- Apply range check for access type case
1901 elsif Is_Access_Type (Etype (Lhs))
1902 and then Nkind (Rhs) = N_Allocator
1903 and then Nkind (Expression (Rhs)) = N_Qualified_Expression
1905 Analyze_And_Resolve (Expression (Rhs));
1907 (Expression (Rhs), Designated_Type (Etype (Lhs)));
1910 -- Ada 2005 (AI-231): Generate the run-time check
1912 if Is_Access_Type (Typ)
1913 and then Can_Never_Be_Null (Etype (Lhs))
1914 and then not Can_Never_Be_Null (Etype (Rhs))
1916 Apply_Constraint_Check (Rhs, Etype (Lhs));
1919 -- Ada 2012 (AI05-148): Update current accessibility level if Rhs is a
1920 -- stand-alone obj of an anonymous access type.
1922 if Is_Access_Type (Typ)
1923 and then Is_Entity_Name (Lhs)
1924 and then Present (Effective_Extra_Accessibility (Entity (Lhs))) then
1926 function Lhs_Entity return Entity_Id;
1927 -- Look through renames to find the underlying entity.
1928 -- For assignment to a rename, we don't care about the
1929 -- Enclosing_Dynamic_Scope of the rename declaration.
1935 function Lhs_Entity return Entity_Id is
1936 Result : Entity_Id := Entity (Lhs);
1939 while Present (Renamed_Object (Result)) loop
1941 -- Renamed_Object must return an Entity_Name here
1942 -- because of preceding "Present (E_E_A (...))" test.
1944 Result := Entity (Renamed_Object (Result));
1950 -- Local Declarations
1952 Access_Check : constant Node_Id :=
1953 Make_Raise_Program_Error (Loc,
1957 Dynamic_Accessibility_Level (Rhs),
1959 Make_Integer_Literal (Loc,
1962 (Enclosing_Dynamic_Scope
1964 Reason => PE_Accessibility_Check_Failed);
1966 Access_Level_Update : constant Node_Id :=
1967 Make_Assignment_Statement (Loc,
1970 (Effective_Extra_Accessibility
1971 (Entity (Lhs)), Loc),
1973 Dynamic_Accessibility_Level (Rhs));
1976 if not Accessibility_Checks_Suppressed (Entity (Lhs)) then
1977 Insert_Action (N, Access_Check);
1980 Insert_Action (N, Access_Level_Update);
1984 -- Case of assignment to a bit packed array element. If there is a
1985 -- change of representation this must be expanded into components,
1986 -- otherwise this is a bit-field assignment.
1988 if Nkind (Lhs) = N_Indexed_Component
1989 and then Is_Bit_Packed_Array (Etype (Prefix (Lhs)))
1991 -- Normal case, no change of representation
1994 Expand_Bit_Packed_Element_Set (N);
1997 -- Change of representation case
2000 -- Generate the following, to force component-by-component
2001 -- assignments in an efficient way. Otherwise each component
2002 -- will require a temporary and two bit-field manipulations.
2009 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T');
2015 Make_Object_Declaration (Loc,
2016 Defining_Identifier => Tnn,
2017 Object_Definition =>
2018 New_Occurrence_Of (Etype (Lhs), Loc)),
2019 Make_Assignment_Statement (Loc,
2020 Name => New_Occurrence_Of (Tnn, Loc),
2021 Expression => Relocate_Node (Rhs)),
2022 Make_Assignment_Statement (Loc,
2023 Name => Relocate_Node (Lhs),
2024 Expression => New_Occurrence_Of (Tnn, Loc)));
2026 Insert_Actions (N, Stats);
2027 Rewrite (N, Make_Null_Statement (Loc));
2032 -- Build-in-place function call case. Note that we're not yet doing
2033 -- build-in-place for user-written assignment statements (the assignment
2034 -- here came from an aggregate.)
2036 elsif Ada_Version >= Ada_2005
2037 and then Is_Build_In_Place_Function_Call (Rhs)
2039 Make_Build_In_Place_Call_In_Assignment (N, Rhs);
2041 elsif Is_Tagged_Type (Typ) and then Is_Value_Type (Etype (Lhs)) then
2043 -- Nothing to do for valuetypes
2044 -- ??? Set_Scope_Is_Transient (False);
2048 elsif Is_Tagged_Type (Typ)
2049 or else (Needs_Finalization (Typ) and then not Is_Array_Type (Typ))
2051 Tagged_Case : declare
2052 L : List_Id := No_List;
2053 Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N);
2056 -- In the controlled case, we ensure that function calls are
2057 -- evaluated before finalizing the target. In all cases, it makes
2058 -- the expansion easier if the side-effects are removed first.
2060 Remove_Side_Effects (Lhs);
2061 Remove_Side_Effects (Rhs);
2063 -- Avoid recursion in the mechanism
2067 -- If dispatching assignment, we need to dispatch to _assign
2069 if Is_Class_Wide_Type (Typ)
2071 -- If the type is tagged, we may as well use the predefined
2072 -- primitive assignment. This avoids inlining a lot of code
2073 -- and in the class-wide case, the assignment is replaced
2074 -- by a dispatching call to _assign. It is suppressed in the
2075 -- case of assignments created by the expander that correspond
2076 -- to initializations, where we do want to copy the tag
2077 -- (Expand_Ctrl_Actions flag is set True in this case). It is
2078 -- also suppressed if restriction No_Dispatching_Calls is in
2079 -- force because in that case predefined primitives are not
2082 or else (Is_Tagged_Type (Typ)
2083 and then not Is_Value_Type (Etype (Lhs))
2084 and then Chars (Current_Scope) /= Name_uAssign
2085 and then Expand_Ctrl_Actions
2087 not Restriction_Active (No_Dispatching_Calls))
2089 -- Fetch the primitive op _assign and proper type to call it.
2090 -- Because of possible conflicts between private and full view,
2091 -- fetch the proper type directly from the operation profile.
2094 Op : constant Entity_Id :=
2095 Find_Prim_Op (Typ, Name_uAssign);
2096 F_Typ : Entity_Id := Etype (First_Formal (Op));
2099 -- If the assignment is dispatching, make sure to use the
2102 if Is_Class_Wide_Type (Typ) then
2103 F_Typ := Class_Wide_Type (F_Typ);
2108 -- In case of assignment to a class-wide tagged type, before
2109 -- the assignment we generate run-time check to ensure that
2110 -- the tags of source and target match.
2112 if Is_Class_Wide_Type (Typ)
2113 and then Is_Tagged_Type (Typ)
2114 and then Is_Tagged_Type (Underlying_Type (Etype (Rhs)))
2117 Make_Raise_Constraint_Error (Loc,
2121 Make_Selected_Component (Loc,
2122 Prefix => Duplicate_Subexpr (Lhs),
2124 Make_Identifier (Loc, Name_uTag)),
2126 Make_Selected_Component (Loc,
2127 Prefix => Duplicate_Subexpr (Rhs),
2129 Make_Identifier (Loc, Name_uTag))),
2130 Reason => CE_Tag_Check_Failed));
2134 Left_N : Node_Id := Duplicate_Subexpr (Lhs);
2135 Right_N : Node_Id := Duplicate_Subexpr (Rhs);
2138 -- In order to dispatch the call to _assign the type of
2139 -- the actuals must match. Add conversion (if required).
2141 if Etype (Lhs) /= F_Typ then
2142 Left_N := Unchecked_Convert_To (F_Typ, Left_N);
2145 if Etype (Rhs) /= F_Typ then
2146 Right_N := Unchecked_Convert_To (F_Typ, Right_N);
2150 Make_Procedure_Call_Statement (Loc,
2151 Name => New_Reference_To (Op, Loc),
2152 Parameter_Associations => New_List (
2154 Node2 => Right_N)));
2159 L := Make_Tag_Ctrl_Assignment (N);
2161 -- We can't afford to have destructive Finalization Actions in
2162 -- the Self assignment case, so if the target and the source
2163 -- are not obviously different, code is generated to avoid the
2164 -- self assignment case:
2166 -- if lhs'address /= rhs'address then
2167 -- <code for controlled and/or tagged assignment>
2170 -- Skip this if Restriction (No_Finalization) is active
2172 if not Statically_Different (Lhs, Rhs)
2173 and then Expand_Ctrl_Actions
2174 and then not Restriction_Active (No_Finalization)
2177 Make_Implicit_If_Statement (N,
2181 Make_Attribute_Reference (Loc,
2182 Prefix => Duplicate_Subexpr (Lhs),
2183 Attribute_Name => Name_Address),
2186 Make_Attribute_Reference (Loc,
2187 Prefix => Duplicate_Subexpr (Rhs),
2188 Attribute_Name => Name_Address)),
2190 Then_Statements => L));
2193 -- We need to set up an exception handler for implementing
2194 -- 7.6.1(18). The remaining adjustments are tackled by the
2195 -- implementation of adjust for record_controllers (see
2198 -- This is skipped if we have no finalization
2200 if Expand_Ctrl_Actions
2201 and then not Restriction_Active (No_Finalization)
2204 Make_Block_Statement (Loc,
2205 Handled_Statement_Sequence =>
2206 Make_Handled_Sequence_Of_Statements (Loc,
2208 Exception_Handlers => New_List (
2209 Make_Handler_For_Ctrl_Operation (Loc)))));
2214 Make_Block_Statement (Loc,
2215 Handled_Statement_Sequence =>
2216 Make_Handled_Sequence_Of_Statements (Loc, Statements => L)));
2218 -- If no restrictions on aborts, protect the whole assignment
2219 -- for controlled objects as per 9.8(11).
2221 if Needs_Finalization (Typ)
2222 and then Expand_Ctrl_Actions
2223 and then Abort_Allowed
2226 Blk : constant Entity_Id :=
2228 (E_Block, Current_Scope, Sloc (N), 'B');
2231 Set_Scope (Blk, Current_Scope);
2232 Set_Etype (Blk, Standard_Void_Type);
2233 Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N)));
2235 Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer));
2236 Set_At_End_Proc (Handled_Statement_Sequence (N),
2237 New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc));
2238 Expand_At_End_Handler
2239 (Handled_Statement_Sequence (N), Blk);
2243 -- N has been rewritten to a block statement for which it is
2244 -- known by construction that no checks are necessary: analyze
2245 -- it with all checks suppressed.
2247 Analyze (N, Suppress => All_Checks);
2253 elsif Is_Array_Type (Typ) then
2255 Actual_Rhs : Node_Id := Rhs;
2258 while Nkind_In (Actual_Rhs, N_Type_Conversion,
2259 N_Qualified_Expression)
2261 Actual_Rhs := Expression (Actual_Rhs);
2264 Expand_Assign_Array (N, Actual_Rhs);
2270 elsif Is_Record_Type (Typ) then
2271 Expand_Assign_Record (N);
2274 -- Scalar types. This is where we perform the processing related to the
2275 -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid
2278 elsif Is_Scalar_Type (Typ) then
2280 -- Case where right side is known valid
2282 if Expr_Known_Valid (Rhs) then
2284 -- Here the right side is valid, so it is fine. The case to deal
2285 -- with is when the left side is a local variable reference whose
2286 -- value is not currently known to be valid. If this is the case,
2287 -- and the assignment appears in an unconditional context, then
2288 -- we can mark the left side as now being valid if one of these
2289 -- conditions holds:
2291 -- The expression of the right side has Do_Range_Check set so
2292 -- that we know a range check will be performed. Note that it
2293 -- can be the case that a range check is omitted because we
2294 -- make the assumption that we can assume validity for operands
2295 -- appearing in the right side in determining whether a range
2296 -- check is required
2298 -- The subtype of the right side matches the subtype of the
2299 -- left side. In this case, even though we have not checked
2300 -- the range of the right side, we know it is in range of its
2301 -- subtype if the expression is valid.
2303 if Is_Local_Variable_Reference (Lhs)
2304 and then not Is_Known_Valid (Entity (Lhs))
2305 and then In_Unconditional_Context (N)
2307 if Do_Range_Check (Rhs)
2308 or else Etype (Lhs) = Etype (Rhs)
2310 Set_Is_Known_Valid (Entity (Lhs), True);
2314 -- Case where right side may be invalid in the sense of the RM
2315 -- reference above. The RM does not require that we check for the
2316 -- validity on an assignment, but it does require that the assignment
2317 -- of an invalid value not cause erroneous behavior.
2319 -- The general approach in GNAT is to use the Is_Known_Valid flag
2320 -- to avoid the need for validity checking on assignments. However
2321 -- in some cases, we have to do validity checking in order to make
2322 -- sure that the setting of this flag is correct.
2325 -- Validate right side if we are validating copies
2327 if Validity_Checks_On
2328 and then Validity_Check_Copies
2330 -- Skip this if left hand side is an array or record component
2331 -- and elementary component validity checks are suppressed.
2333 if Nkind_In (Lhs, N_Selected_Component, N_Indexed_Component)
2334 and then not Validity_Check_Components
2341 -- We can propagate this to the left side where appropriate
2343 if Is_Local_Variable_Reference (Lhs)
2344 and then not Is_Known_Valid (Entity (Lhs))
2345 and then In_Unconditional_Context (N)
2347 Set_Is_Known_Valid (Entity (Lhs), True);
2350 -- Otherwise check to see what should be done
2352 -- If left side is a local variable, then we just set its flag to
2353 -- indicate that its value may no longer be valid, since we are
2354 -- copying a potentially invalid value.
2356 elsif Is_Local_Variable_Reference (Lhs) then
2357 Set_Is_Known_Valid (Entity (Lhs), False);
2359 -- Check for case of a nonlocal variable on the left side which
2360 -- is currently known to be valid. In this case, we simply ensure
2361 -- that the right side is valid. We only play the game of copying
2362 -- validity status for local variables, since we are doing this
2363 -- statically, not by tracing the full flow graph.
2365 elsif Is_Entity_Name (Lhs)
2366 and then Is_Known_Valid (Entity (Lhs))
2368 -- Note: If Validity_Checking mode is set to none, we ignore
2369 -- the Ensure_Valid call so don't worry about that case here.
2373 -- In all other cases, we can safely copy an invalid value without
2374 -- worrying about the status of the left side. Since it is not a
2375 -- variable reference it will not be considered
2376 -- as being known to be valid in any case.
2385 when RE_Not_Available =>
2387 end Expand_N_Assignment_Statement;
2389 ------------------------------
2390 -- Expand_N_Block_Statement --
2391 ------------------------------
2393 -- Encode entity names defined in block statement
2395 procedure Expand_N_Block_Statement (N : Node_Id) is
2397 Qualify_Entity_Names (N);
2398 end Expand_N_Block_Statement;
2400 -----------------------------
2401 -- Expand_N_Case_Statement --
2402 -----------------------------
2404 procedure Expand_N_Case_Statement (N : Node_Id) is
2405 Loc : constant Source_Ptr := Sloc (N);
2406 Expr : constant Node_Id := Expression (N);
2414 -- Check for the situation where we know at compile time which branch
2417 if Compile_Time_Known_Value (Expr) then
2418 Alt := Find_Static_Alternative (N);
2420 Process_Statements_For_Controlled_Objects (Alt);
2422 -- Move statements from this alternative after the case statement.
2423 -- They are already analyzed, so will be skipped by the analyzer.
2425 Insert_List_After (N, Statements (Alt));
2427 -- That leaves the case statement as a shell. So now we can kill all
2428 -- other alternatives in the case statement.
2430 Kill_Dead_Code (Expression (N));
2436 -- Loop through case alternatives, skipping pragmas, and skipping
2437 -- the one alternative that we select (and therefore retain).
2439 Dead_Alt := First (Alternatives (N));
2440 while Present (Dead_Alt) loop
2442 and then Nkind (Dead_Alt) = N_Case_Statement_Alternative
2444 Kill_Dead_Code (Statements (Dead_Alt), Warn_On_Deleted_Code);
2451 Rewrite (N, Make_Null_Statement (Loc));
2455 -- Here if the choice is not determined at compile time
2458 Last_Alt : constant Node_Id := Last (Alternatives (N));
2460 Others_Present : Boolean;
2461 Others_Node : Node_Id;
2463 Then_Stms : List_Id;
2464 Else_Stms : List_Id;
2467 if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then
2468 Others_Present := True;
2469 Others_Node := Last_Alt;
2471 Others_Present := False;
2474 -- First step is to worry about possible invalid argument. The RM
2475 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
2476 -- outside the base range), then Constraint_Error must be raised.
2478 -- Case of validity check required (validity checks are on, the
2479 -- expression is not known to be valid, and the case statement
2480 -- comes from source -- no need to validity check internally
2481 -- generated case statements).
2483 if Validity_Check_Default then
2484 Ensure_Valid (Expr);
2487 -- If there is only a single alternative, just replace it with the
2488 -- sequence of statements since obviously that is what is going to
2489 -- be executed in all cases.
2491 Len := List_Length (Alternatives (N));
2495 -- We still need to evaluate the expression if it has any side
2498 Remove_Side_Effects (Expression (N));
2500 Alt := First (Alternatives (N));
2502 Process_Statements_For_Controlled_Objects (Alt);
2503 Insert_List_After (N, Statements (Alt));
2505 -- That leaves the case statement as a shell. The alternative that
2506 -- will be executed is reset to a null list. So now we can kill
2507 -- the entire case statement.
2509 Kill_Dead_Code (Expression (N));
2510 Rewrite (N, Make_Null_Statement (Loc));
2513 -- An optimization. If there are only two alternatives, and only
2514 -- a single choice, then rewrite the whole case statement as an
2515 -- if statement, since this can result in subsequent optimizations.
2516 -- This helps not only with case statements in the source of a
2517 -- simple form, but also with generated code (discriminant check
2518 -- functions in particular)
2521 Chlist := Discrete_Choices (First (Alternatives (N)));
2523 if List_Length (Chlist) = 1 then
2524 Choice := First (Chlist);
2526 Then_Stms := Statements (First (Alternatives (N)));
2527 Else_Stms := Statements (Last (Alternatives (N)));
2529 -- For TRUE, generate "expression", not expression = true
2531 if Nkind (Choice) = N_Identifier
2532 and then Entity (Choice) = Standard_True
2534 Cond := Expression (N);
2536 -- For FALSE, generate "expression" and switch then/else
2538 elsif Nkind (Choice) = N_Identifier
2539 and then Entity (Choice) = Standard_False
2541 Cond := Expression (N);
2542 Else_Stms := Statements (First (Alternatives (N)));
2543 Then_Stms := Statements (Last (Alternatives (N)));
2545 -- For a range, generate "expression in range"
2547 elsif Nkind (Choice) = N_Range
2548 or else (Nkind (Choice) = N_Attribute_Reference
2549 and then Attribute_Name (Choice) = Name_Range)
2550 or else (Is_Entity_Name (Choice)
2551 and then Is_Type (Entity (Choice)))
2552 or else Nkind (Choice) = N_Subtype_Indication
2556 Left_Opnd => Expression (N),
2557 Right_Opnd => Relocate_Node (Choice));
2559 -- For any other subexpression "expression = value"
2564 Left_Opnd => Expression (N),
2565 Right_Opnd => Relocate_Node (Choice));
2568 -- Now rewrite the case as an IF
2571 Make_If_Statement (Loc,
2573 Then_Statements => Then_Stms,
2574 Else_Statements => Else_Stms));
2580 -- If the last alternative is not an Others choice, replace it with
2581 -- an N_Others_Choice. Note that we do not bother to call Analyze on
2582 -- the modified case statement, since it's only effect would be to
2583 -- compute the contents of the Others_Discrete_Choices which is not
2584 -- needed by the back end anyway.
2586 -- The reason we do this is that the back end always needs some
2587 -- default for a switch, so if we have not supplied one in the
2588 -- processing above for validity checking, then we need to supply
2591 if not Others_Present then
2592 Others_Node := Make_Others_Choice (Sloc (Last_Alt));
2593 Set_Others_Discrete_Choices
2594 (Others_Node, Discrete_Choices (Last_Alt));
2595 Set_Discrete_Choices (Last_Alt, New_List (Others_Node));
2598 Alt := First (Alternatives (N));
2600 and then Nkind (Alt) = N_Case_Statement_Alternative
2602 Process_Statements_For_Controlled_Objects (Alt);
2606 end Expand_N_Case_Statement;
2608 -----------------------------
2609 -- Expand_N_Exit_Statement --
2610 -----------------------------
2612 -- The only processing required is to deal with a possible C/Fortran
2613 -- boolean value used as the condition for the exit statement.
2615 procedure Expand_N_Exit_Statement (N : Node_Id) is
2617 Adjust_Condition (Condition (N));
2618 end Expand_N_Exit_Statement;
2620 -----------------------------
2621 -- Expand_N_Goto_Statement --
2622 -----------------------------
2624 -- Add poll before goto if polling active
2626 procedure Expand_N_Goto_Statement (N : Node_Id) is
2628 Generate_Poll_Call (N);
2629 end Expand_N_Goto_Statement;
2631 ---------------------------
2632 -- Expand_N_If_Statement --
2633 ---------------------------
2635 -- First we deal with the case of C and Fortran convention boolean values,
2636 -- with zero/non-zero semantics.
2638 -- Second, we deal with the obvious rewriting for the cases where the
2639 -- condition of the IF is known at compile time to be True or False.
2641 -- Third, we remove elsif parts which have non-empty Condition_Actions and
2642 -- rewrite as independent if statements. For example:
2653 -- <<condition actions of y>>
2659 -- This rewriting is needed if at least one elsif part has a non-empty
2660 -- Condition_Actions list. We also do the same processing if there is a
2661 -- constant condition in an elsif part (in conjunction with the first
2662 -- processing step mentioned above, for the recursive call made to deal
2663 -- with the created inner if, this deals with properly optimizing the
2664 -- cases of constant elsif conditions).
2666 procedure Expand_N_If_Statement (N : Node_Id) is
2667 Loc : constant Source_Ptr := Sloc (N);
2672 Warn_If_Deleted : constant Boolean :=
2673 Warn_On_Deleted_Code and then Comes_From_Source (N);
2674 -- Indicates whether we want warnings when we delete branches of the
2675 -- if statement based on constant condition analysis. We never want
2676 -- these warnings for expander generated code.
2679 Process_Statements_For_Controlled_Objects (N);
2681 Adjust_Condition (Condition (N));
2683 -- The following loop deals with constant conditions for the IF. We
2684 -- need a loop because as we eliminate False conditions, we grab the
2685 -- first elsif condition and use it as the primary condition.
2687 while Compile_Time_Known_Value (Condition (N)) loop
2689 -- If condition is True, we can simply rewrite the if statement now
2690 -- by replacing it by the series of then statements.
2692 if Is_True (Expr_Value (Condition (N))) then
2694 -- All the else parts can be killed
2696 Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted);
2697 Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted);
2699 Hed := Remove_Head (Then_Statements (N));
2700 Insert_List_After (N, Then_Statements (N));
2704 -- If condition is False, then we can delete the condition and
2705 -- the Then statements
2708 -- We do not delete the condition if constant condition warnings
2709 -- are enabled, since otherwise we end up deleting the desired
2710 -- warning. Of course the backend will get rid of this True/False
2711 -- test anyway, so nothing is lost here.
2713 if not Constant_Condition_Warnings then
2714 Kill_Dead_Code (Condition (N));
2717 Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted);
2719 -- If there are no elsif statements, then we simply replace the
2720 -- entire if statement by the sequence of else statements.
2722 if No (Elsif_Parts (N)) then
2723 if No (Else_Statements (N))
2724 or else Is_Empty_List (Else_Statements (N))
2727 Make_Null_Statement (Sloc (N)));
2729 Hed := Remove_Head (Else_Statements (N));
2730 Insert_List_After (N, Else_Statements (N));
2736 -- If there are elsif statements, the first of them becomes the
2737 -- if/then section of the rebuilt if statement This is the case
2738 -- where we loop to reprocess this copied condition.
2741 Hed := Remove_Head (Elsif_Parts (N));
2742 Insert_Actions (N, Condition_Actions (Hed));
2743 Set_Condition (N, Condition (Hed));
2744 Set_Then_Statements (N, Then_Statements (Hed));
2746 -- Hed might have been captured as the condition determining
2747 -- the current value for an entity. Now it is detached from
2748 -- the tree, so a Current_Value pointer in the condition might
2749 -- need to be updated.
2751 Set_Current_Value_Condition (N);
2753 if Is_Empty_List (Elsif_Parts (N)) then
2754 Set_Elsif_Parts (N, No_List);
2760 -- Loop through elsif parts, dealing with constant conditions and
2761 -- possible expression actions that are present.
2763 if Present (Elsif_Parts (N)) then
2764 E := First (Elsif_Parts (N));
2765 while Present (E) loop
2766 Process_Statements_For_Controlled_Objects (E);
2768 Adjust_Condition (Condition (E));
2770 -- If there are condition actions, then rewrite the if statement
2771 -- as indicated above. We also do the same rewrite for a True or
2772 -- False condition. The further processing of this constant
2773 -- condition is then done by the recursive call to expand the
2774 -- newly created if statement
2776 if Present (Condition_Actions (E))
2777 or else Compile_Time_Known_Value (Condition (E))
2779 -- Note this is not an implicit if statement, since it is part
2780 -- of an explicit if statement in the source (or of an implicit
2781 -- if statement that has already been tested).
2784 Make_If_Statement (Sloc (E),
2785 Condition => Condition (E),
2786 Then_Statements => Then_Statements (E),
2787 Elsif_Parts => No_List,
2788 Else_Statements => Else_Statements (N));
2790 -- Elsif parts for new if come from remaining elsif's of parent
2792 while Present (Next (E)) loop
2793 if No (Elsif_Parts (New_If)) then
2794 Set_Elsif_Parts (New_If, New_List);
2797 Append (Remove_Next (E), Elsif_Parts (New_If));
2800 Set_Else_Statements (N, New_List (New_If));
2802 if Present (Condition_Actions (E)) then
2803 Insert_List_Before (New_If, Condition_Actions (E));
2808 if Is_Empty_List (Elsif_Parts (N)) then
2809 Set_Elsif_Parts (N, No_List);
2815 -- No special processing for that elsif part, move to next
2823 -- Some more optimizations applicable if we still have an IF statement
2825 if Nkind (N) /= N_If_Statement then
2829 -- Another optimization, special cases that can be simplified
2831 -- if expression then
2837 -- can be changed to:
2839 -- return expression;
2843 -- if expression then
2849 -- can be changed to:
2851 -- return not (expression);
2853 -- Only do these optimizations if we are at least at -O1 level and
2854 -- do not do them if control flow optimizations are suppressed.
2856 if Optimization_Level > 0
2857 and then not Opt.Suppress_Control_Flow_Optimizations
2859 if Nkind (N) = N_If_Statement
2860 and then No (Elsif_Parts (N))
2861 and then Present (Else_Statements (N))
2862 and then List_Length (Then_Statements (N)) = 1
2863 and then List_Length (Else_Statements (N)) = 1
2866 Then_Stm : constant Node_Id := First (Then_Statements (N));
2867 Else_Stm : constant Node_Id := First (Else_Statements (N));
2870 if Nkind (Then_Stm) = N_Simple_Return_Statement
2872 Nkind (Else_Stm) = N_Simple_Return_Statement
2875 Then_Expr : constant Node_Id := Expression (Then_Stm);
2876 Else_Expr : constant Node_Id := Expression (Else_Stm);
2879 if Nkind (Then_Expr) = N_Identifier
2881 Nkind (Else_Expr) = N_Identifier
2883 if Entity (Then_Expr) = Standard_True
2884 and then Entity (Else_Expr) = Standard_False
2887 Make_Simple_Return_Statement (Loc,
2888 Expression => Relocate_Node (Condition (N))));
2892 elsif Entity (Then_Expr) = Standard_False
2893 and then Entity (Else_Expr) = Standard_True
2896 Make_Simple_Return_Statement (Loc,
2900 Relocate_Node (Condition (N)))));
2910 end Expand_N_If_Statement;
2912 --------------------------
2913 -- Expand_Iterator_Loop --
2914 --------------------------
2916 procedure Expand_Iterator_Loop (N : Node_Id) is
2917 Isc : constant Node_Id := Iteration_Scheme (N);
2918 I_Spec : constant Node_Id := Iterator_Specification (Isc);
2919 Id : constant Entity_Id := Defining_Identifier (I_Spec);
2920 Loc : constant Source_Ptr := Sloc (N);
2922 Container : constant Node_Id := Name (I_Spec);
2923 Container_Typ : constant Entity_Id := Base_Type (Etype (Container));
2925 Iterator : Entity_Id;
2927 Stats : List_Id := Statements (N);
2930 -- Processing for arrays
2932 if Is_Array_Type (Container_Typ) then
2934 -- for Element of Array loop
2936 -- This case requires an internally generated cursor to iterate over
2939 if Of_Present (I_Spec) then
2940 Iterator := Make_Temporary (Loc, 'C');
2943 -- Element : Component_Type renames Container (Iterator);
2946 Make_Object_Renaming_Declaration (Loc,
2947 Defining_Identifier => Id,
2949 New_Reference_To (Component_Type (Container_Typ), Loc),
2951 Make_Indexed_Component (Loc,
2952 Prefix => Relocate_Node (Container),
2953 Expressions => New_List (
2954 New_Reference_To (Iterator, Loc)))));
2956 -- for Index in Array loop
2958 -- This case utilizes the already given iterator name
2965 -- for Iterator in [reverse] Container'Range loop
2966 -- Element : Component_Type renames Container (Iterator);
2967 -- -- for the "of" form
2969 -- <original loop statements>
2973 Make_Loop_Statement (Loc,
2975 Make_Iteration_Scheme (Loc,
2976 Loop_Parameter_Specification =>
2977 Make_Loop_Parameter_Specification (Loc,
2978 Defining_Identifier => Iterator,
2979 Discrete_Subtype_Definition =>
2980 Make_Attribute_Reference (Loc,
2981 Prefix => Relocate_Node (Container),
2982 Attribute_Name => Name_Range),
2983 Reverse_Present => Reverse_Present (I_Spec))),
2984 Statements => Stats,
2985 End_Label => Empty);
2987 -- Processing for containers
2990 -- For an "of" iterator the name is a container expression, which
2991 -- is transformed into a call to the default iterator.
2993 -- For an iterator of the form "in" the name is a function call
2994 -- that delivers an iterator type.
2996 -- In both cases, analysis of the iterator has introduced an object
2997 -- declaration to capture the domain, so that Container is an entity.
2999 -- The for loop is expanded into a while loop which uses a container
3000 -- specific cursor to desgnate each element.
3002 -- Iter : Iterator_Type := Container.Iterate;
3003 -- Cursor : Cursor_type := First (Iter);
3004 -- while Has_Element (Iter) loop
3006 -- -- The block is added when Element_Type is controlled
3008 -- Obj : Pack.Element_Type := Element (Cursor);
3009 -- -- for the "of" loop form
3011 -- <original loop statements>
3014 -- Cursor := Iter.Next (Cursor);
3017 -- If "reverse" is present, then the initialization of the cursor
3018 -- uses Last and the step becomes Prev. Pack is the name of the
3019 -- scope where the container package is instantiated.
3022 Element_Type : constant Entity_Id := Etype (Id);
3023 Iter_Type : Entity_Id;
3026 Name_Init : Name_Id;
3027 Name_Step : Name_Id;
3030 -- The type of the iterator is the return type of the Iterate
3031 -- function used. For the "of" form this is the default iterator
3032 -- for the type, otherwise it is the type of the explicit
3033 -- function used in the iterator specification. The most common
3034 -- case will be an Iterate function in the container package.
3036 -- The primitive operations of the container type may not be
3037 -- use-visible, so we introduce the name of the enclosing package
3038 -- in the declarations below. The Iterator type is declared in a
3039 -- an instance within the container package itself.
3041 -- If the container type is a derived type, the cursor type is
3042 -- found in the package of the parent type.
3044 if Is_Derived_Type (Container_Typ) then
3045 Pack := Scope (Root_Type (Container_Typ));
3047 Pack := Scope (Container_Typ);
3050 Iter_Type := Etype (Name (I_Spec));
3052 -- The "of" case uses an internally generated cursor whose type
3053 -- is found in the container package. The domain of iteration
3054 -- is expanded into a call to the default Iterator function, but
3055 -- this expansion does not take place in quantified expressions
3056 -- that are analyzed with expansion disabled, and in that case the
3057 -- type of the iterator must be obtained from the aspect.
3059 if Of_Present (I_Spec) then
3061 Default_Iter : constant Entity_Id :=
3065 Aspect_Default_Iterator));
3067 Container_Arg : Node_Id;
3071 Cursor := Make_Temporary (Loc, 'I');
3073 -- For an container element iterator, the iterator type
3074 -- is obtained from the corresponding aspect.
3076 Iter_Type := Etype (Default_Iter);
3077 Pack := Scope (Iter_Type);
3079 -- Rewrite domain of iteration as a call to the default
3080 -- iterator for the container type. If the container is
3081 -- a derived type and the aspect is inherited, convert
3082 -- container to parent type. The Cursor type is also
3083 -- inherited from the scope of the parent.
3085 if Base_Type (Etype (Container)) =
3086 Base_Type (Etype (First_Formal (Default_Iter)))
3088 Container_Arg := New_Copy_Tree (Container);
3092 Make_Type_Conversion (Loc,
3095 (Etype (First_Formal (Default_Iter)), Loc),
3096 Expression => New_Copy_Tree (Container));
3099 Rewrite (Name (I_Spec),
3100 Make_Function_Call (Loc,
3101 Name => New_Occurrence_Of (Default_Iter, Loc),
3102 Parameter_Associations =>
3103 New_List (Container_Arg)));
3104 Analyze_And_Resolve (Name (I_Spec));
3106 -- Find cursor type in proper iterator package, which is an
3107 -- instantiation of Iterator_Interfaces.
3109 Ent := First_Entity (Pack);
3110 while Present (Ent) loop
3111 if Chars (Ent) = Name_Cursor then
3112 Set_Etype (Cursor, Etype (Ent));
3119 -- Id : Element_Type renames Container (Cursor);
3120 -- This assumes that the container type has an indexing
3121 -- operation with Cursor. The check that this operation
3122 -- exists is performed in Check_Container_Indexing.
3125 Make_Object_Renaming_Declaration (Loc,
3126 Defining_Identifier => Id,
3128 New_Reference_To (Element_Type, Loc),
3130 Make_Indexed_Component (Loc,
3131 Prefix => Relocate_Node (Container_Arg),
3133 New_List (New_Occurrence_Of (Cursor, Loc))));
3135 -- If the container holds controlled objects, wrap the loop
3136 -- statements and element renaming declaration with a block.
3137 -- This ensures that the result of Element (Cusor) is
3138 -- cleaned up after each iteration of the loop.
3140 if Needs_Finalization (Element_Type) then
3144 -- Id : Element_Type := Element (curosr);
3146 -- <original loop statements>
3150 Make_Block_Statement (Loc,
3151 Declarations => New_List (Decl),
3152 Handled_Statement_Sequence =>
3153 Make_Handled_Sequence_Of_Statements (Loc,
3154 Statements => Stats)));
3156 -- Elements do not need finalization
3159 Prepend_To (Stats, Decl);
3163 -- X in Iterate (S) : type of iterator is type of explicitly
3164 -- given Iterate function, and the loop variable is the cursor.
3165 -- It will be assigned in the loop and must be a variable.
3169 Set_Ekind (Cursor, E_Variable);
3172 Iterator := Make_Temporary (Loc, 'I');
3174 -- Determine the advancement and initialization steps for the
3177 -- Analysis of the expanded loop will verify that the container
3178 -- has a reverse iterator.
3180 if Reverse_Present (I_Spec) then
3181 Name_Init := Name_Last;
3182 Name_Step := Name_Previous;
3185 Name_Init := Name_First;
3186 Name_Step := Name_Next;
3189 -- For both iterator forms, add a call to the step operation to
3190 -- advance the cursor. Generate:
3192 -- Cursor := Iterator.Next (Cursor);
3196 -- Cursor := Next (Cursor);
3203 Make_Function_Call (Loc,
3205 Make_Selected_Component (Loc,
3206 Prefix => New_Reference_To (Iterator, Loc),
3207 Selector_Name => Make_Identifier (Loc, Name_Step)),
3208 Parameter_Associations => New_List (
3209 New_Reference_To (Cursor, Loc)));
3212 Make_Assignment_Statement (Loc,
3213 Name => New_Occurrence_Of (Cursor, Loc),
3214 Expression => Rhs));
3218 -- while Iterator.Has_Element loop
3222 -- Has_Element is the second actual in the iterator package
3225 Make_Loop_Statement (Loc,
3227 Make_Iteration_Scheme (Loc,
3229 Make_Function_Call (Loc,
3232 Next_Entity (First_Entity (Pack)), Loc),
3233 Parameter_Associations =>
3235 New_Reference_To (Cursor, Loc)))),
3237 Statements => Stats,
3238 End_Label => Empty);
3240 -- Create the declarations for Iterator and cursor and insert them
3241 -- before the source loop. Given that the domain of iteration is
3242 -- already an entity, the iterator is just a renaming of that
3243 -- entity. Possible optimization ???
3246 -- I : Iterator_Type renames Container;
3247 -- C : Cursor_Type := Container.[First | Last];
3250 Make_Object_Renaming_Declaration (Loc,
3251 Defining_Identifier => Iterator,
3252 Subtype_Mark => New_Occurrence_Of (Iter_Type, Loc),
3253 Name => Relocate_Node (Name (I_Spec))));
3255 -- Create declaration for cursor
3262 Make_Object_Declaration (Loc,
3263 Defining_Identifier => Cursor,
3264 Object_Definition =>
3265 New_Occurrence_Of (Etype (Cursor), Loc),
3267 Make_Selected_Component (Loc,
3268 Prefix => New_Reference_To (Iterator, Loc),
3270 Make_Identifier (Loc, Name_Init)));
3272 -- The cursor is only modified in expanded code, so it appears
3273 -- as unassigned to the warning machinery. We must suppress
3274 -- this spurious warning explicitly.
3276 Set_Warnings_Off (Cursor);
3277 Set_Assignment_OK (Decl);
3279 Insert_Action (N, Decl);
3282 -- If the range of iteration is given by a function call that
3283 -- returns a container, the finalization actions have been saved
3284 -- in the Condition_Actions of the iterator. Insert them now at
3285 -- the head of the loop.
3287 if Present (Condition_Actions (Isc)) then
3288 Insert_List_Before (N, Condition_Actions (Isc));
3293 Rewrite (N, New_Loop);
3295 end Expand_Iterator_Loop;
3297 -----------------------------
3298 -- Expand_N_Loop_Statement --
3299 -----------------------------
3301 -- 1. Remove null loop entirely
3302 -- 2. Deal with while condition for C/Fortran boolean
3303 -- 3. Deal with loops with a non-standard enumeration type range
3304 -- 4. Deal with while loops where Condition_Actions is set
3305 -- 5. Deal with loops over predicated subtypes
3306 -- 6. Deal with loops with iterators over arrays and containers
3307 -- 7. Insert polling call if required
3309 procedure Expand_N_Loop_Statement (N : Node_Id) is
3310 Loc : constant Source_Ptr := Sloc (N);
3311 Isc : constant Node_Id := Iteration_Scheme (N);
3316 if Is_Null_Loop (N) then
3317 Rewrite (N, Make_Null_Statement (Loc));
3321 Process_Statements_For_Controlled_Objects (N);
3323 -- Deal with condition for C/Fortran Boolean
3325 if Present (Isc) then
3326 Adjust_Condition (Condition (Isc));
3329 -- Generate polling call
3331 if Is_Non_Empty_List (Statements (N)) then
3332 Generate_Poll_Call (First (Statements (N)));
3335 -- Nothing more to do for plain loop with no iteration scheme
3340 -- Case of for loop (Loop_Parameter_Specification present)
3342 -- Note: we do not have to worry about validity checking of the for loop
3343 -- range bounds here, since they were frozen with constant declarations
3344 -- and it is during that process that the validity checking is done.
3346 elsif Present (Loop_Parameter_Specification (Isc)) then
3348 LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
3349 Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
3350 Ltype : constant Entity_Id := Etype (Loop_Id);
3351 Btype : constant Entity_Id := Base_Type (Ltype);
3356 -- Deal with loop over predicates
3358 if Is_Discrete_Type (Ltype)
3359 and then Present (Predicate_Function (Ltype))
3361 Expand_Predicated_Loop (N);
3363 -- Handle the case where we have a for loop with the range type
3364 -- being an enumeration type with non-standard representation.
3365 -- In this case we expand:
3367 -- for x in [reverse] a .. b loop
3373 -- for xP in [reverse] integer
3374 -- range etype'Pos (a) .. etype'Pos (b)
3377 -- x : constant etype := Pos_To_Rep (xP);
3383 elsif Is_Enumeration_Type (Btype)
3384 and then Present (Enum_Pos_To_Rep (Btype))
3387 Make_Defining_Identifier (Loc,
3388 Chars => New_External_Name (Chars (Loop_Id), 'P'));
3390 -- If the type has a contiguous representation, successive
3391 -- values can be generated as offsets from the first literal.
3393 if Has_Contiguous_Rep (Btype) then
3395 Unchecked_Convert_To (Btype,
3398 Make_Integer_Literal (Loc,
3399 Enumeration_Rep (First_Literal (Btype))),
3400 Right_Opnd => New_Reference_To (New_Id, Loc)));
3402 -- Use the constructed array Enum_Pos_To_Rep
3405 Make_Indexed_Component (Loc,
3407 New_Reference_To (Enum_Pos_To_Rep (Btype), Loc),
3409 New_List (New_Reference_To (New_Id, Loc)));
3413 Make_Loop_Statement (Loc,
3414 Identifier => Identifier (N),
3417 Make_Iteration_Scheme (Loc,
3418 Loop_Parameter_Specification =>
3419 Make_Loop_Parameter_Specification (Loc,
3420 Defining_Identifier => New_Id,
3421 Reverse_Present => Reverse_Present (LPS),
3423 Discrete_Subtype_Definition =>
3424 Make_Subtype_Indication (Loc,
3427 New_Reference_To (Standard_Natural, Loc),
3430 Make_Range_Constraint (Loc,
3435 Make_Attribute_Reference (Loc,
3437 New_Reference_To (Btype, Loc),
3439 Attribute_Name => Name_Pos,
3441 Expressions => New_List (
3443 (Type_Low_Bound (Ltype)))),
3446 Make_Attribute_Reference (Loc,
3448 New_Reference_To (Btype, Loc),
3450 Attribute_Name => Name_Pos,
3452 Expressions => New_List (
3457 Statements => New_List (
3458 Make_Block_Statement (Loc,
3459 Declarations => New_List (
3460 Make_Object_Declaration (Loc,
3461 Defining_Identifier => Loop_Id,
3462 Constant_Present => True,
3463 Object_Definition =>
3464 New_Reference_To (Ltype, Loc),
3465 Expression => Expr)),
3467 Handled_Statement_Sequence =>
3468 Make_Handled_Sequence_Of_Statements (Loc,
3469 Statements => Statements (N)))),
3471 End_Label => End_Label (N)));
3473 -- The loop parameter's entity must be removed from the loop
3474 -- scope's entity list, since it will now be located in the
3475 -- new block scope. Any other entities already associated with
3476 -- the loop scope, such as the loop parameter's subtype, will
3479 pragma Assert (First_Entity (Scope (Loop_Id)) = Loop_Id);
3480 Set_First_Entity (Scope (Loop_Id), Next_Entity (Loop_Id));
3482 if Last_Entity (Scope (Loop_Id)) = Loop_Id then
3483 Set_Last_Entity (Scope (Loop_Id), Empty);
3488 -- Nothing to do with other cases of for loops
3495 -- Second case, if we have a while loop with Condition_Actions set, then
3496 -- we change it into a plain loop:
3505 -- <<condition actions>>
3511 and then Present (Condition_Actions (Isc))
3512 and then Present (Condition (Isc))
3519 Make_Exit_Statement (Sloc (Condition (Isc)),
3521 Make_Op_Not (Sloc (Condition (Isc)),
3522 Right_Opnd => Condition (Isc)));
3524 Prepend (ES, Statements (N));
3525 Insert_List_Before (ES, Condition_Actions (Isc));
3527 -- This is not an implicit loop, since it is generated in response
3528 -- to the loop statement being processed. If this is itself
3529 -- implicit, the restriction has already been checked. If not,
3530 -- it is an explicit loop.
3533 Make_Loop_Statement (Sloc (N),
3534 Identifier => Identifier (N),
3535 Statements => Statements (N),
3536 End_Label => End_Label (N)));
3541 -- Here to deal with iterator case
3544 and then Present (Iterator_Specification (Isc))
3546 Expand_Iterator_Loop (N);
3548 end Expand_N_Loop_Statement;
3550 ----------------------------
3551 -- Expand_Predicated_Loop --
3552 ----------------------------
3554 -- Note: the expander can handle generation of loops over predicated
3555 -- subtypes for both the dynamic and static cases. Depending on what
3556 -- we decide is allowed in Ada 2012 mode and/or extensions allowed
3557 -- mode, the semantic analyzer may disallow one or both forms.
3559 procedure Expand_Predicated_Loop (N : Node_Id) is
3560 Loc : constant Source_Ptr := Sloc (N);
3561 Isc : constant Node_Id := Iteration_Scheme (N);
3562 LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
3563 Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
3564 Ltype : constant Entity_Id := Etype (Loop_Id);
3565 Stat : constant List_Id := Static_Predicate (Ltype);
3566 Stmts : constant List_Id := Statements (N);
3569 -- Case of iteration over non-static predicate, should not be possible
3570 -- since this is not allowed by the semantics and should have been
3571 -- caught during analysis of the loop statement.
3574 raise Program_Error;
3576 -- If the predicate list is empty, that corresponds to a predicate of
3577 -- False, in which case the loop won't run at all, and we rewrite the
3578 -- entire loop as a null statement.
3580 elsif Is_Empty_List (Stat) then
3581 Rewrite (N, Make_Null_Statement (Loc));
3584 -- For expansion over a static predicate we generate the following
3587 -- J : Ltype := min-val;
3592 -- when endpoint => J := startpoint;
3593 -- when endpoint => J := startpoint;
3595 -- when max-val => exit;
3596 -- when others => J := Lval'Succ (J);
3601 -- To make this a little clearer, let's take a specific example:
3603 -- type Int is range 1 .. 10;
3604 -- subtype L is Int with
3605 -- predicate => L in 3 | 10 | 5 .. 7;
3607 -- for L in StaticP loop
3608 -- Put_Line ("static:" & J'Img);
3611 -- In this case, the loop is transformed into
3618 -- when 3 => J := 5;
3619 -- when 7 => J := 10;
3621 -- when others => J := L'Succ (J);
3627 Static_Predicate : declare
3634 function Lo_Val (N : Node_Id) return Node_Id;
3635 -- Given static expression or static range, returns an identifier
3636 -- whose value is the low bound of the expression value or range.
3638 function Hi_Val (N : Node_Id) return Node_Id;
3639 -- Given static expression or static range, returns an identifier
3640 -- whose value is the high bound of the expression value or range.
3646 function Hi_Val (N : Node_Id) return Node_Id is
3648 if Is_Static_Expression (N) then
3649 return New_Copy (N);
3651 pragma Assert (Nkind (N) = N_Range);
3652 return New_Copy (High_Bound (N));
3660 function Lo_Val (N : Node_Id) return Node_Id is
3662 if Is_Static_Expression (N) then
3663 return New_Copy (N);
3665 pragma Assert (Nkind (N) = N_Range);
3666 return New_Copy (Low_Bound (N));
3670 -- Start of processing for Static_Predicate
3673 -- Convert loop identifier to normal variable and reanalyze it so
3674 -- that this conversion works. We have to use the same defining
3675 -- identifier, since there may be references in the loop body.
3677 Set_Analyzed (Loop_Id, False);
3678 Set_Ekind (Loop_Id, E_Variable);
3680 -- Loop to create branches of case statement
3684 while Present (P) loop
3685 if No (Next (P)) then
3686 S := Make_Exit_Statement (Loc);
3689 Make_Assignment_Statement (Loc,
3690 Name => New_Occurrence_Of (Loop_Id, Loc),
3691 Expression => Lo_Val (Next (P)));
3692 Set_Suppress_Assignment_Checks (S);
3696 Make_Case_Statement_Alternative (Loc,
3697 Statements => New_List (S),
3698 Discrete_Choices => New_List (Hi_Val (P))));
3703 -- Add others choice
3706 Make_Assignment_Statement (Loc,
3707 Name => New_Occurrence_Of (Loop_Id, Loc),
3709 Make_Attribute_Reference (Loc,
3710 Prefix => New_Occurrence_Of (Ltype, Loc),
3711 Attribute_Name => Name_Succ,
3712 Expressions => New_List (
3713 New_Occurrence_Of (Loop_Id, Loc))));
3714 Set_Suppress_Assignment_Checks (S);
3717 Make_Case_Statement_Alternative (Loc,
3718 Discrete_Choices => New_List (Make_Others_Choice (Loc)),
3719 Statements => New_List (S)));
3721 -- Construct case statement and append to body statements
3724 Make_Case_Statement (Loc,
3725 Expression => New_Occurrence_Of (Loop_Id, Loc),
3726 Alternatives => Alts);
3727 Append_To (Stmts, Cstm);
3732 Make_Object_Declaration (Loc,
3733 Defining_Identifier => Loop_Id,
3734 Object_Definition => New_Occurrence_Of (Ltype, Loc),
3735 Expression => Lo_Val (First (Stat)));
3736 Set_Suppress_Assignment_Checks (D);
3739 Make_Block_Statement (Loc,
3740 Declarations => New_List (D),
3741 Handled_Statement_Sequence =>
3742 Make_Handled_Sequence_Of_Statements (Loc,
3743 Statements => New_List (
3744 Make_Loop_Statement (Loc,
3745 Statements => Stmts,
3746 End_Label => Empty)))));
3749 end Static_Predicate;
3751 end Expand_Predicated_Loop;
3753 ------------------------------
3754 -- Make_Tag_Ctrl_Assignment --
3755 ------------------------------
3757 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is
3758 Asn : constant Node_Id := Relocate_Node (N);
3759 L : constant Node_Id := Name (N);
3760 Loc : constant Source_Ptr := Sloc (N);
3761 Res : constant List_Id := New_List;
3762 T : constant Entity_Id := Underlying_Type (Etype (L));
3764 Comp_Asn : constant Boolean := Is_Fully_Repped_Tagged_Type (T);
3765 Ctrl_Act : constant Boolean := Needs_Finalization (T)
3766 and then not No_Ctrl_Actions (N);
3767 Save_Tag : constant Boolean := Is_Tagged_Type (T)
3768 and then not Comp_Asn
3769 and then not No_Ctrl_Actions (N)
3770 and then Tagged_Type_Expansion;
3771 -- Tags are not saved and restored when VM_Target because VM tags are
3772 -- represented implicitly in objects.
3774 Next_Id : Entity_Id;
3775 Prev_Id : Entity_Id;
3779 -- Finalize the target of the assignment when controlled
3781 -- We have two exceptions here:
3783 -- 1. If we are in an init proc since it is an initialization more
3784 -- than an assignment.
3786 -- 2. If the left-hand side is a temporary that was not initialized
3787 -- (or the parent part of a temporary since it is the case in
3788 -- extension aggregates). Such a temporary does not come from
3789 -- source. We must examine the original node for the prefix, because
3790 -- it may be a component of an entry formal, in which case it has
3791 -- been rewritten and does not appear to come from source either.
3793 -- Case of init proc
3795 if not Ctrl_Act then
3798 -- The left hand side is an uninitialized temporary object
3800 elsif Nkind (L) = N_Type_Conversion
3801 and then Is_Entity_Name (Expression (L))
3802 and then Nkind (Parent (Entity (Expression (L)))) =
3803 N_Object_Declaration
3804 and then No_Initialization (Parent (Entity (Expression (L))))
3811 (Obj_Ref => Duplicate_Subexpr_No_Checks (L),
3815 -- Save the Tag in a local variable Tag_Id
3818 Tag_Id := Make_Temporary (Loc, 'A');
3821 Make_Object_Declaration (Loc,
3822 Defining_Identifier => Tag_Id,
3823 Object_Definition => New_Reference_To (RTE (RE_Tag), Loc),
3825 Make_Selected_Component (Loc,
3826 Prefix => Duplicate_Subexpr_No_Checks (L),
3828 New_Reference_To (First_Tag_Component (T), Loc))));
3830 -- Otherwise Tag_Id is not used
3836 -- Save the Prev and Next fields on .NET/JVM. This is not needed on non
3837 -- VM targets since the fields are not part of the object.
3839 if VM_Target /= No_VM
3840 and then Is_Controlled (T)
3842 Prev_Id := Make_Temporary (Loc, 'P');
3843 Next_Id := Make_Temporary (Loc, 'N');
3846 -- Pnn : Root_Controlled_Ptr := Root_Controlled (L).Prev;
3849 Make_Object_Declaration (Loc,
3850 Defining_Identifier => Prev_Id,
3851 Object_Definition =>
3852 New_Reference_To (RTE (RE_Root_Controlled_Ptr), Loc),
3854 Make_Selected_Component (Loc,
3856 Unchecked_Convert_To
3857 (RTE (RE_Root_Controlled), New_Copy_Tree (L)),
3859 Make_Identifier (Loc, Name_Prev))));
3862 -- Nnn : Root_Controlled_Ptr := Root_Controlled (L).Next;
3865 Make_Object_Declaration (Loc,
3866 Defining_Identifier => Next_Id,
3867 Object_Definition =>
3868 New_Reference_To (RTE (RE_Root_Controlled_Ptr), Loc),
3870 Make_Selected_Component (Loc,
3872 Unchecked_Convert_To
3873 (RTE (RE_Root_Controlled), New_Copy_Tree (L)),
3875 Make_Identifier (Loc, Name_Next))));
3878 -- If the tagged type has a full rep clause, expand the assignment into
3879 -- component-wise assignments. Mark the node as unanalyzed in order to
3880 -- generate the proper code and propagate this scenario by setting a
3881 -- flag to avoid infinite recursion.
3884 Set_Analyzed (Asn, False);
3885 Set_Componentwise_Assignment (Asn, True);
3888 Append_To (Res, Asn);
3894 Make_Assignment_Statement (Loc,
3896 Make_Selected_Component (Loc,
3897 Prefix => Duplicate_Subexpr_No_Checks (L),
3899 New_Reference_To (First_Tag_Component (T), Loc)),
3900 Expression => New_Reference_To (Tag_Id, Loc)));
3903 -- Restore the Prev and Next fields on .NET/JVM
3905 if VM_Target /= No_VM
3906 and then Is_Controlled (T)
3909 -- Root_Controlled (L).Prev := Prev_Id;
3912 Make_Assignment_Statement (Loc,
3914 Make_Selected_Component (Loc,
3916 Unchecked_Convert_To
3917 (RTE (RE_Root_Controlled), New_Copy_Tree (L)),
3919 Make_Identifier (Loc, Name_Prev)),
3920 Expression => New_Reference_To (Prev_Id, Loc)));
3923 -- Root_Controlled (L).Next := Next_Id;
3926 Make_Assignment_Statement (Loc,
3928 Make_Selected_Component (Loc,
3930 Unchecked_Convert_To
3931 (RTE (RE_Root_Controlled), New_Copy_Tree (L)),
3932 Selector_Name => Make_Identifier (Loc, Name_Next)),
3933 Expression => New_Reference_To (Next_Id, Loc)));
3936 -- Adjust the target after the assignment when controlled (not in the
3937 -- init proc since it is an initialization more than an assignment).
3942 (Obj_Ref => Duplicate_Subexpr_Move_Checks (L),
3950 -- Could use comment here ???
3952 when RE_Not_Available =>
3954 end Make_Tag_Ctrl_Assignment;