1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2004, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 with Atree; use Atree;
28 with Checks; use Checks;
29 with Einfo; use Einfo;
30 with Exp_Aggr; use Exp_Aggr;
31 with Exp_Ch7; use Exp_Ch7;
32 with Exp_Ch11; use Exp_Ch11;
33 with Exp_Dbug; use Exp_Dbug;
34 with Exp_Pakd; use Exp_Pakd;
35 with Exp_Tss; use Exp_Tss;
36 with Exp_Util; use Exp_Util;
37 with Hostparm; use Hostparm;
38 with Nlists; use Nlists;
39 with Nmake; use Nmake;
41 with Restrict; use Restrict;
42 with Rident; use Rident;
43 with Rtsfind; use Rtsfind;
44 with Sinfo; use Sinfo;
46 with Sem_Ch3; use Sem_Ch3;
47 with Sem_Ch8; use Sem_Ch8;
48 with Sem_Ch13; use Sem_Ch13;
49 with Sem_Eval; use Sem_Eval;
50 with Sem_Res; use Sem_Res;
51 with Sem_Util; use Sem_Util;
52 with Snames; use Snames;
53 with Stand; use Stand;
54 with Stringt; use Stringt;
55 with Tbuild; use Tbuild;
56 with Ttypes; use Ttypes;
57 with Uintp; use Uintp;
58 with Validsw; use Validsw;
60 package body Exp_Ch5 is
62 function Change_Of_Representation (N : Node_Id) return Boolean;
63 -- Determine if the right hand side of the assignment N is a type
64 -- conversion which requires a change of representation. Called
65 -- only for the array and record cases.
67 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id);
68 -- N is an assignment which assigns an array value. This routine process
69 -- the various special cases and checks required for such assignments,
70 -- including change of representation. Rhs is normally simply the right
71 -- hand side of the assignment, except that if the right hand side is
72 -- a type conversion or a qualified expression, then the Rhs is the
73 -- actual expression inside any such type conversions or qualifications.
75 function Expand_Assign_Array_Loop
82 Rev : Boolean) return Node_Id;
83 -- N is an assignment statement which assigns an array value. This routine
84 -- expands the assignment into a loop (or nested loops for the case of a
85 -- multi-dimensional array) to do the assignment component by component.
86 -- Larray and Rarray are the entities of the actual arrays on the left
87 -- hand and right hand sides. L_Type and R_Type are the types of these
88 -- arrays (which may not be the same, due to either sliding, or to a
89 -- change of representation case). Ndim is the number of dimensions and
90 -- the parameter Rev indicates if the loops run normally (Rev = False),
91 -- or reversed (Rev = True). The value returned is the constructed
92 -- loop statement. Auxiliary declarations are inserted before node N
93 -- using the standard Insert_Actions mechanism.
95 procedure Expand_Assign_Record (N : Node_Id);
96 -- N is an assignment of a non-tagged record value. This routine handles
97 -- the case where the assignment must be made component by component,
98 -- either because the target is not byte aligned, or there is a change
101 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
102 -- Generate the necessary code for controlled and tagged assignment,
103 -- that is to say, finalization of the target before, adjustement of
104 -- the target after and save and restore of the tag and finalization
105 -- pointers which are not 'part of the value' and must not be changed
106 -- upon assignment. N is the original Assignment node.
108 function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean;
109 -- This function is used in processing the assignment of a record or
110 -- indexed component. The argument N is either the left hand or right
111 -- hand side of an assignment, and this function determines if there
112 -- is a record component reference where the record may be bit aligned
113 -- in a manner that causes trouble for the back end (see description
114 -- of Exp_Util.Component_May_Be_Bit_Aligned for further details).
116 ------------------------------
117 -- Change_Of_Representation --
118 ------------------------------
120 function Change_Of_Representation (N : Node_Id) return Boolean is
121 Rhs : constant Node_Id := Expression (N);
124 Nkind (Rhs) = N_Type_Conversion
126 not Same_Representation (Etype (Rhs), Etype (Expression (Rhs)));
127 end Change_Of_Representation;
129 -------------------------
130 -- Expand_Assign_Array --
131 -------------------------
133 -- There are two issues here. First, do we let Gigi do a block move, or
134 -- do we expand out into a loop? Second, we need to set the two flags
135 -- Forwards_OK and Backwards_OK which show whether the block move (or
136 -- corresponding loops) can be legitimately done in a forwards (low to
137 -- high) or backwards (high to low) manner.
139 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is
140 Loc : constant Source_Ptr := Sloc (N);
142 Lhs : constant Node_Id := Name (N);
144 Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs);
145 Act_Rhs : Node_Id := Get_Referenced_Object (Rhs);
147 L_Type : constant Entity_Id :=
148 Underlying_Type (Get_Actual_Subtype (Act_Lhs));
149 R_Type : Entity_Id :=
150 Underlying_Type (Get_Actual_Subtype (Act_Rhs));
152 L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice;
153 R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice;
155 Crep : constant Boolean := Change_Of_Representation (N);
160 Ndim : constant Pos := Number_Dimensions (L_Type);
162 Loop_Required : Boolean := False;
163 -- This switch is set to True if the array move must be done using
164 -- an explicit front end generated loop.
166 procedure Apply_Dereference (Arg : in out Node_Id);
167 -- If the argument is an access to an array, and the assignment is
168 -- converted into a procedure call, apply explicit dereference.
170 function Has_Address_Clause (Exp : Node_Id) return Boolean;
171 -- Test if Exp is a reference to an array whose declaration has
172 -- an address clause, or it is a slice of such an array.
174 function Is_Formal_Array (Exp : Node_Id) return Boolean;
175 -- Test if Exp is a reference to an array which is either a formal
176 -- parameter or a slice of a formal parameter. These are the cases
177 -- where hidden aliasing can occur.
179 function Is_Non_Local_Array (Exp : Node_Id) return Boolean;
180 -- Determine if Exp is a reference to an array variable which is other
181 -- than an object defined in the current scope, or a slice of such
182 -- an object. Such objects can be aliased to parameters (unlike local
183 -- array references).
185 -----------------------
186 -- Apply_Dereference --
187 -----------------------
189 procedure Apply_Dereference (Arg : in out Node_Id) is
190 Typ : constant Entity_Id := Etype (Arg);
192 if Is_Access_Type (Typ) then
193 Rewrite (Arg, Make_Explicit_Dereference (Loc,
194 Prefix => Relocate_Node (Arg)));
195 Analyze_And_Resolve (Arg, Designated_Type (Typ));
197 end Apply_Dereference;
199 ------------------------
200 -- Has_Address_Clause --
201 ------------------------
203 function Has_Address_Clause (Exp : Node_Id) return Boolean is
206 (Is_Entity_Name (Exp) and then
207 Present (Address_Clause (Entity (Exp))))
209 (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp)));
210 end Has_Address_Clause;
212 ---------------------
213 -- Is_Formal_Array --
214 ---------------------
216 function Is_Formal_Array (Exp : Node_Id) return Boolean is
219 (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp)))
221 (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp)));
224 ------------------------
225 -- Is_Non_Local_Array --
226 ------------------------
228 function Is_Non_Local_Array (Exp : Node_Id) return Boolean is
230 return (Is_Entity_Name (Exp)
231 and then Scope (Entity (Exp)) /= Current_Scope)
232 or else (Nkind (Exp) = N_Slice
233 and then Is_Non_Local_Array (Prefix (Exp)));
234 end Is_Non_Local_Array;
236 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
238 Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs);
239 Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs);
241 Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs);
242 Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs);
244 -- Start of processing for Expand_Assign_Array
247 -- Deal with length check, note that the length check is done with
248 -- respect to the right hand side as given, not a possible underlying
249 -- renamed object, since this would generate incorrect extra checks.
251 Apply_Length_Check (Rhs, L_Type);
253 -- We start by assuming that the move can be done in either
254 -- direction, i.e. that the two sides are completely disjoint.
256 Set_Forwards_OK (N, True);
257 Set_Backwards_OK (N, True);
259 -- Normally it is only the slice case that can lead to overlap,
260 -- and explicit checks for slices are made below. But there is
261 -- one case where the slice can be implicit and invisible to us
262 -- and that is the case where we have a one dimensional array,
263 -- and either both operands are parameters, or one is a parameter
264 -- and the other is a global variable. In this case the parameter
265 -- could be a slice that overlaps with the other parameter.
267 -- Check for the case of slices requiring an explicit loop. Normally
268 -- it is only the explicit slice cases that bother us, but in the
269 -- case of one dimensional arrays, parameters can be slices that
270 -- are passed by reference, so we can have aliasing for assignments
271 -- from one parameter to another, or assignments between parameters
272 -- and nonlocal variables. However, if the array subtype is a
273 -- constrained first subtype in the parameter case, then we don't
274 -- have to worry about overlap, since slice assignments aren't
275 -- possible (other than for a slice denoting the whole array).
277 -- Note: overlap is never possible if there is a change of
278 -- representation, so we can exclude this case.
283 ((Lhs_Formal and Rhs_Formal)
285 (Lhs_Formal and Rhs_Non_Local_Var)
287 (Rhs_Formal and Lhs_Non_Local_Var))
289 (not Is_Constrained (Etype (Lhs))
290 or else not Is_First_Subtype (Etype (Lhs)))
292 -- In the case of compiling for the Java Virtual Machine,
293 -- slices are always passed by making a copy, so we don't
294 -- have to worry about overlap. We also want to prevent
295 -- generation of "<" comparisons for array addresses,
296 -- since that's a meaningless operation on the JVM.
300 Set_Forwards_OK (N, False);
301 Set_Backwards_OK (N, False);
303 -- Note: the bit-packed case is not worrisome here, since if
304 -- we have a slice passed as a parameter, it is always aligned
305 -- on a byte boundary, and if there are no explicit slices, the
306 -- assignment can be performed directly.
309 -- We certainly must use a loop for change of representation
310 -- and also we use the operand of the conversion on the right
311 -- hand side as the effective right hand side (the component
312 -- types must match in this situation).
315 Act_Rhs := Get_Referenced_Object (Rhs);
316 R_Type := Get_Actual_Subtype (Act_Rhs);
317 Loop_Required := True;
319 -- We require a loop if the left side is possibly bit unaligned
321 elsif Possible_Bit_Aligned_Component (Lhs)
323 Possible_Bit_Aligned_Component (Rhs)
325 Loop_Required := True;
327 -- Arrays with controlled components are expanded into a loop
328 -- to force calls to adjust at the component level.
330 elsif Has_Controlled_Component (L_Type) then
331 Loop_Required := True;
333 -- Case where no slice is involved
335 elsif not L_Slice and not R_Slice then
337 -- The following code deals with the case of unconstrained bit
338 -- packed arrays. The problem is that the template for such
339 -- arrays contains the bounds of the actual source level array,
341 -- But the copy of an entire array requires the bounds of the
342 -- underlying array. It would be nice if the back end could take
343 -- care of this, but right now it does not know how, so if we
344 -- have such a type, then we expand out into a loop, which is
345 -- inefficient but works correctly. If we don't do this, we
346 -- get the wrong length computed for the array to be moved.
347 -- The two cases we need to worry about are:
349 -- Explicit deference of an unconstrained packed array type as
350 -- in the following example:
353 -- type BITS is array(INTEGER range <>) of BOOLEAN;
354 -- pragma PACK(BITS);
355 -- type A is access BITS;
358 -- P1 := new BITS (1 .. 65_535);
359 -- P2 := new BITS (1 .. 65_535);
363 -- A formal parameter reference with an unconstrained bit
364 -- array type is the other case we need to worry about (here
365 -- we assume the same BITS type declared above:
367 -- procedure Write_All (File : out BITS; Contents : in BITS);
369 -- File.Storage := Contents;
372 -- We expand to a loop in either of these two cases.
374 -- Question for future thought. Another potentially more efficient
375 -- approach would be to create the actual subtype, and then do an
376 -- unchecked conversion to this actual subtype ???
378 Check_Unconstrained_Bit_Packed_Array : declare
380 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean;
381 -- Function to perform required test for the first case,
382 -- above (dereference of an unconstrained bit packed array)
384 -----------------------
385 -- Is_UBPA_Reference --
386 -----------------------
388 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is
389 Typ : constant Entity_Id := Underlying_Type (Etype (Opnd));
391 Des_Type : Entity_Id;
394 if Present (Packed_Array_Type (Typ))
395 and then Is_Array_Type (Packed_Array_Type (Typ))
396 and then not Is_Constrained (Packed_Array_Type (Typ))
400 elsif Nkind (Opnd) = N_Explicit_Dereference then
401 P_Type := Underlying_Type (Etype (Prefix (Opnd)));
403 if not Is_Access_Type (P_Type) then
407 Des_Type := Designated_Type (P_Type);
409 Is_Bit_Packed_Array (Des_Type)
410 and then not Is_Constrained (Des_Type);
416 end Is_UBPA_Reference;
418 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
421 if Is_UBPA_Reference (Lhs)
423 Is_UBPA_Reference (Rhs)
425 Loop_Required := True;
427 -- Here if we do not have the case of a reference to a bit
428 -- packed unconstrained array case. In this case gigi can
429 -- most certainly handle the assignment if a forwards move
432 -- (could it handle the backwards case also???)
434 elsif Forwards_OK (N) then
437 end Check_Unconstrained_Bit_Packed_Array;
439 -- Gigi can always handle the assignment if the right side is a string
440 -- literal (note that overlap is definitely impossible in this case).
441 -- If the type is packed, a string literal is always converted into a
442 -- aggregate, except in the case of a null slice, for which no aggregate
443 -- can be written. In that case, rewrite the assignment as a null
444 -- statement, a length check has already been emitted to verify that
445 -- the range of the left-hand side is empty.
447 -- Note that this code is not executed if we had an assignment of
448 -- a string literal to a non-bit aligned component of a record, a
449 -- case which cannot be handled by the backend
451 elsif Nkind (Rhs) = N_String_Literal then
452 if String_Length (Strval (Rhs)) = 0
453 and then Is_Bit_Packed_Array (L_Type)
455 Rewrite (N, Make_Null_Statement (Loc));
461 -- If either operand is bit packed, then we need a loop, since we
462 -- can't be sure that the slice is byte aligned. Similarly, if either
463 -- operand is a possibly unaligned slice, then we need a loop (since
464 -- gigi cannot handle unaligned slices).
466 elsif Is_Bit_Packed_Array (L_Type)
467 or else Is_Bit_Packed_Array (R_Type)
468 or else Is_Possibly_Unaligned_Slice (Lhs)
469 or else Is_Possibly_Unaligned_Slice (Rhs)
471 Loop_Required := True;
473 -- If we are not bit-packed, and we have only one slice, then no
474 -- overlap is possible except in the parameter case, so we can let
475 -- gigi handle things.
477 elsif not (L_Slice and R_Slice) then
478 if Forwards_OK (N) then
483 -- If the right-hand side is a string literal, introduce a temporary
484 -- for it, for use in the generated loop that will follow.
486 if Nkind (Rhs) = N_String_Literal then
488 Temp : constant Entity_Id :=
489 Make_Defining_Identifier (Loc, Name_T);
494 Make_Object_Declaration (Loc,
495 Defining_Identifier => Temp,
496 Object_Definition => New_Occurrence_Of (L_Type, Loc),
497 Expression => Relocate_Node (Rhs));
499 Insert_Action (N, Decl);
500 Rewrite (Rhs, New_Occurrence_Of (Temp, Loc));
501 R_Type := Etype (Temp);
505 -- Come here to complete the analysis
507 -- Loop_Required: Set to True if we know that a loop is required
508 -- regardless of overlap considerations.
510 -- Forwards_OK: Set to False if we already know that a forwards
511 -- move is not safe, else set to True.
513 -- Backwards_OK: Set to False if we already know that a backwards
514 -- move is not safe, else set to True
516 -- Our task at this stage is to complete the overlap analysis, which
517 -- can result in possibly setting Forwards_OK or Backwards_OK to
518 -- False, and then generating the final code, either by deciding
519 -- that it is OK after all to let Gigi handle it, or by generating
520 -- appropriate code in the front end.
523 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
524 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type));
526 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ);
527 Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ);
528 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ);
529 Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ);
531 Act_L_Array : Node_Id;
532 Act_R_Array : Node_Id;
538 Cresult : Compare_Result;
541 -- Get the expressions for the arrays. If we are dealing with a
542 -- private type, then convert to the underlying type. We can do
543 -- direct assignments to an array that is a private type, but
544 -- we cannot assign to elements of the array without this extra
545 -- unchecked conversion.
547 if Nkind (Act_Lhs) = N_Slice then
548 Larray := Prefix (Act_Lhs);
552 if Is_Private_Type (Etype (Larray)) then
555 (Underlying_Type (Etype (Larray)), Larray);
559 if Nkind (Act_Rhs) = N_Slice then
560 Rarray := Prefix (Act_Rhs);
564 if Is_Private_Type (Etype (Rarray)) then
567 (Underlying_Type (Etype (Rarray)), Rarray);
571 -- If both sides are slices, we must figure out whether
572 -- it is safe to do the move in one direction or the other
573 -- It is always safe if there is a change of representation
574 -- since obviously two arrays with different representations
575 -- cannot possibly overlap.
577 if (not Crep) and L_Slice and R_Slice then
578 Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
579 Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
581 -- If both left and right hand arrays are entity names, and
582 -- refer to different entities, then we know that the move
583 -- is safe (the two storage areas are completely disjoint).
585 if Is_Entity_Name (Act_L_Array)
586 and then Is_Entity_Name (Act_R_Array)
587 and then Entity (Act_L_Array) /= Entity (Act_R_Array)
591 -- Otherwise, we assume the worst, which is that the two
592 -- arrays are the same array. There is no need to check if
593 -- we know that is the case, because if we don't know it,
594 -- we still have to assume it!
596 -- Generally if the same array is involved, then we have
597 -- an overlapping case. We will have to really assume the
598 -- worst (i.e. set neither of the OK flags) unless we can
599 -- determine the lower or upper bounds at compile time and
603 Cresult := Compile_Time_Compare (Left_Lo, Right_Lo);
605 if Cresult = Unknown then
606 Cresult := Compile_Time_Compare (Left_Hi, Right_Hi);
610 when LT | LE | EQ => Set_Backwards_OK (N, False);
611 when GT | GE => Set_Forwards_OK (N, False);
612 when NE | Unknown => Set_Backwards_OK (N, False);
613 Set_Forwards_OK (N, False);
618 -- If after that analysis, Forwards_OK is still True, and
619 -- Loop_Required is False, meaning that we have not discovered
620 -- some non-overlap reason for requiring a loop, then we can
621 -- still let gigi handle it.
623 if not Loop_Required then
624 if Forwards_OK (N) then
629 -- Here is where a memmove would be appropriate ???
633 -- At this stage we have to generate an explicit loop, and
634 -- we have the following cases:
636 -- Forwards_OK = True
638 -- Rnn : right_index := right_index'First;
639 -- for Lnn in left-index loop
640 -- left (Lnn) := right (Rnn);
641 -- Rnn := right_index'Succ (Rnn);
644 -- Note: the above code MUST be analyzed with checks off,
645 -- because otherwise the Succ could overflow. But in any
646 -- case this is more efficient!
648 -- Forwards_OK = False, Backwards_OK = True
650 -- Rnn : right_index := right_index'Last;
651 -- for Lnn in reverse left-index loop
652 -- left (Lnn) := right (Rnn);
653 -- Rnn := right_index'Pred (Rnn);
656 -- Note: the above code MUST be analyzed with checks off,
657 -- because otherwise the Pred could overflow. But in any
658 -- case this is more efficient!
660 -- Forwards_OK = Backwards_OK = False
662 -- This only happens if we have the same array on each side. It is
663 -- possible to create situations using overlays that violate this,
664 -- but we simply do not promise to get this "right" in this case.
666 -- There are two possible subcases. If the No_Implicit_Conditionals
667 -- restriction is set, then we generate the following code:
670 -- T : constant <operand-type> := rhs;
675 -- If implicit conditionals are permitted, then we generate:
677 -- if Left_Lo <= Right_Lo then
678 -- <code for Forwards_OK = True above>
680 -- <code for Backwards_OK = True above>
683 -- Cases where either Forwards_OK or Backwards_OK is true
685 if Forwards_OK (N) or else Backwards_OK (N) then
686 if Controlled_Type (Component_Type (L_Type))
687 and then Base_Type (L_Type) = Base_Type (R_Type)
689 and then not No_Ctrl_Actions (N)
692 Proc : constant Entity_Id :=
693 TSS (Base_Type (L_Type), TSS_Slice_Assign);
697 Apply_Dereference (Larray);
698 Apply_Dereference (Rarray);
699 Actuals := New_List (
700 Duplicate_Subexpr (Larray, Name_Req => True),
701 Duplicate_Subexpr (Rarray, Name_Req => True),
702 Duplicate_Subexpr (Left_Lo, Name_Req => True),
703 Duplicate_Subexpr (Left_Hi, Name_Req => True),
704 Duplicate_Subexpr (Right_Lo, Name_Req => True),
705 Duplicate_Subexpr (Right_Hi, Name_Req => True));
709 Boolean_Literals (not Forwards_OK (N)), Loc));
712 Make_Procedure_Call_Statement (Loc,
713 Name => New_Reference_To (Proc, Loc),
714 Parameter_Associations => Actuals));
719 Expand_Assign_Array_Loop
720 (N, Larray, Rarray, L_Type, R_Type, Ndim,
721 Rev => not Forwards_OK (N)));
724 -- Case of both are false with No_Implicit_Conditionals
726 elsif Restriction_Active (No_Implicit_Conditionals) then
728 T : constant Entity_Id :=
729 Make_Defining_Identifier (Loc, Chars => Name_T);
733 Make_Block_Statement (Loc,
734 Declarations => New_List (
735 Make_Object_Declaration (Loc,
736 Defining_Identifier => T,
737 Constant_Present => True,
739 New_Occurrence_Of (Etype (Rhs), Loc),
740 Expression => Relocate_Node (Rhs))),
742 Handled_Statement_Sequence =>
743 Make_Handled_Sequence_Of_Statements (Loc,
744 Statements => New_List (
745 Make_Assignment_Statement (Loc,
746 Name => Relocate_Node (Lhs),
747 Expression => New_Occurrence_Of (T, Loc))))));
750 -- Case of both are false with implicit conditionals allowed
753 -- Before we generate this code, we must ensure that the
754 -- left and right side array types are defined. They may
755 -- be itypes, and we cannot let them be defined inside the
756 -- if, since the first use in the then may not be executed.
758 Ensure_Defined (L_Type, N);
759 Ensure_Defined (R_Type, N);
761 -- We normally compare addresses to find out which way round
762 -- to do the loop, since this is realiable, and handles the
763 -- cases of parameters, conversions etc. But we can't do that
764 -- in the bit packed case or the Java VM case, because addresses
767 if not Is_Bit_Packed_Array (L_Type) and then not Java_VM then
771 Unchecked_Convert_To (RTE (RE_Integer_Address),
772 Make_Attribute_Reference (Loc,
774 Make_Indexed_Component (Loc,
776 Duplicate_Subexpr_Move_Checks (Larray, True),
777 Expressions => New_List (
778 Make_Attribute_Reference (Loc,
782 Attribute_Name => Name_First))),
783 Attribute_Name => Name_Address)),
786 Unchecked_Convert_To (RTE (RE_Integer_Address),
787 Make_Attribute_Reference (Loc,
789 Make_Indexed_Component (Loc,
791 Duplicate_Subexpr_Move_Checks (Rarray, True),
792 Expressions => New_List (
793 Make_Attribute_Reference (Loc,
797 Attribute_Name => Name_First))),
798 Attribute_Name => Name_Address)));
800 -- For the bit packed and Java VM cases we use the bounds.
801 -- That's OK, because we don't have to worry about parameters,
802 -- since they cannot cause overlap. Perhaps we should worry
803 -- about weird slice conversions ???
806 -- Copy the bounds and reset the Analyzed flag, because the
807 -- bounds of the index type itself may be universal, and must
808 -- must be reaanalyzed to acquire the proper type for Gigi.
810 Cleft_Lo := New_Copy_Tree (Left_Lo);
811 Cright_Lo := New_Copy_Tree (Right_Lo);
812 Set_Analyzed (Cleft_Lo, False);
813 Set_Analyzed (Cright_Lo, False);
817 Left_Opnd => Cleft_Lo,
818 Right_Opnd => Cright_Lo);
821 if Controlled_Type (Component_Type (L_Type))
822 and then Base_Type (L_Type) = Base_Type (R_Type)
824 and then not No_Ctrl_Actions (N)
827 -- Call TSS procedure for array assignment, passing the
828 -- the explicit bounds of right- and left-hand side.
831 Proc : constant Node_Id :=
832 TSS (Base_Type (L_Type), TSS_Slice_Assign);
836 Apply_Dereference (Larray);
837 Apply_Dereference (Rarray);
838 Actuals := New_List (
839 Duplicate_Subexpr (Larray, Name_Req => True),
840 Duplicate_Subexpr (Rarray, Name_Req => True),
841 Duplicate_Subexpr (Left_Lo, Name_Req => True),
842 Duplicate_Subexpr (Left_Hi, Name_Req => True),
843 Duplicate_Subexpr (Right_Lo, Name_Req => True),
844 Duplicate_Subexpr (Right_Hi, Name_Req => True));
848 Right_Opnd => Condition));
851 Make_Procedure_Call_Statement (Loc,
852 Name => New_Reference_To (Proc, Loc),
853 Parameter_Associations => Actuals));
858 Make_Implicit_If_Statement (N,
859 Condition => Condition,
861 Then_Statements => New_List (
862 Expand_Assign_Array_Loop
863 (N, Larray, Rarray, L_Type, R_Type, Ndim,
866 Else_Statements => New_List (
867 Expand_Assign_Array_Loop
868 (N, Larray, Rarray, L_Type, R_Type, Ndim,
873 Analyze (N, Suppress => All_Checks);
877 when RE_Not_Available =>
879 end Expand_Assign_Array;
881 ------------------------------
882 -- Expand_Assign_Array_Loop --
883 ------------------------------
885 -- The following is an example of the loop generated for the case of
886 -- a two-dimensional array:
891 -- for L1b in 1 .. 100 loop
895 -- for L3b in 1 .. 100 loop
896 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
897 -- R4b := Tm1X2'succ(R4b);
900 -- R2b := Tm1X1'succ(R2b);
904 -- Here Rev is False, and Tm1Xn are the subscript types for the right
905 -- hand side. The declarations of R2b and R4b are inserted before the
906 -- original assignment statement.
908 function Expand_Assign_Array_Loop
915 Rev : Boolean) return Node_Id
917 Loc : constant Source_Ptr := Sloc (N);
919 Lnn : array (1 .. Ndim) of Entity_Id;
920 Rnn : array (1 .. Ndim) of Entity_Id;
921 -- Entities used as subscripts on left and right sides
923 L_Index_Type : array (1 .. Ndim) of Entity_Id;
924 R_Index_Type : array (1 .. Ndim) of Entity_Id;
925 -- Left and right index types
937 F_Or_L := Name_First;
941 -- Setup index types and subscript entities
948 L_Index := First_Index (L_Type);
949 R_Index := First_Index (R_Type);
951 for J in 1 .. Ndim loop
953 Make_Defining_Identifier (Loc,
954 Chars => New_Internal_Name ('L'));
957 Make_Defining_Identifier (Loc,
958 Chars => New_Internal_Name ('R'));
960 L_Index_Type (J) := Etype (L_Index);
961 R_Index_Type (J) := Etype (R_Index);
963 Next_Index (L_Index);
964 Next_Index (R_Index);
968 -- Now construct the assignment statement
971 ExprL : constant List_Id := New_List;
972 ExprR : constant List_Id := New_List;
975 for J in 1 .. Ndim loop
976 Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc));
977 Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc));
981 Make_Assignment_Statement (Loc,
983 Make_Indexed_Component (Loc,
984 Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
985 Expressions => ExprL),
987 Make_Indexed_Component (Loc,
988 Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
989 Expressions => ExprR));
991 -- Propagate the No_Ctrl_Actions flag to individual assignments
993 Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
996 -- Now construct the loop from the inside out, with the last subscript
997 -- varying most rapidly. Note that Assign is first the raw assignment
998 -- statement, and then subsequently the loop that wraps it up.
1000 for J in reverse 1 .. Ndim loop
1002 Make_Block_Statement (Loc,
1003 Declarations => New_List (
1004 Make_Object_Declaration (Loc,
1005 Defining_Identifier => Rnn (J),
1006 Object_Definition =>
1007 New_Occurrence_Of (R_Index_Type (J), Loc),
1009 Make_Attribute_Reference (Loc,
1010 Prefix => New_Occurrence_Of (R_Index_Type (J), Loc),
1011 Attribute_Name => F_Or_L))),
1013 Handled_Statement_Sequence =>
1014 Make_Handled_Sequence_Of_Statements (Loc,
1015 Statements => New_List (
1016 Make_Implicit_Loop_Statement (N,
1018 Make_Iteration_Scheme (Loc,
1019 Loop_Parameter_Specification =>
1020 Make_Loop_Parameter_Specification (Loc,
1021 Defining_Identifier => Lnn (J),
1022 Reverse_Present => Rev,
1023 Discrete_Subtype_Definition =>
1024 New_Reference_To (L_Index_Type (J), Loc))),
1026 Statements => New_List (
1029 Make_Assignment_Statement (Loc,
1030 Name => New_Occurrence_Of (Rnn (J), Loc),
1032 Make_Attribute_Reference (Loc,
1034 New_Occurrence_Of (R_Index_Type (J), Loc),
1035 Attribute_Name => S_Or_P,
1036 Expressions => New_List (
1037 New_Occurrence_Of (Rnn (J), Loc)))))))));
1041 end Expand_Assign_Array_Loop;
1043 --------------------------
1044 -- Expand_Assign_Record --
1045 --------------------------
1047 -- The only processing required is in the change of representation
1048 -- case, where we must expand the assignment to a series of field
1049 -- by field assignments.
1051 procedure Expand_Assign_Record (N : Node_Id) is
1052 Lhs : constant Node_Id := Name (N);
1053 Rhs : Node_Id := Expression (N);
1056 -- If change of representation, then extract the real right hand
1057 -- side from the type conversion, and proceed with component-wise
1058 -- assignment, since the two types are not the same as far as the
1059 -- back end is concerned.
1061 if Change_Of_Representation (N) then
1062 Rhs := Expression (Rhs);
1064 -- If this may be a case of a large bit aligned component, then
1065 -- proceed with component-wise assignment, to avoid possible
1066 -- clobbering of other components sharing bits in the first or
1067 -- last byte of the component to be assigned.
1069 elsif Possible_Bit_Aligned_Component (Lhs)
1071 Possible_Bit_Aligned_Component (Rhs)
1075 -- If neither condition met, then nothing special to do, the back end
1076 -- can handle assignment of the entire component as a single entity.
1082 -- At this stage we know that we must do a component wise assignment
1085 Loc : constant Source_Ptr := Sloc (N);
1086 R_Typ : constant Entity_Id := Base_Type (Etype (Rhs));
1087 L_Typ : constant Entity_Id := Base_Type (Etype (Lhs));
1088 Decl : constant Node_Id := Declaration_Node (R_Typ);
1092 function Find_Component
1094 Comp : Entity_Id) return Entity_Id;
1095 -- Find the component with the given name in the underlying record
1096 -- declaration for Typ. We need to use the actual entity because
1097 -- the type may be private and resolution by identifier alone would
1100 function Make_Component_List_Assign
1102 U_U : Boolean := False) return List_Id;
1103 -- Returns a sequence of statements to assign the components that
1104 -- are referenced in the given component list. The flag U_U is
1105 -- used to force the usage of the inferred value of the variant
1106 -- part expression as the switch for the generated case statement.
1108 function Make_Field_Assign
1110 U_U : Boolean := False) return Node_Id;
1111 -- Given C, the entity for a discriminant or component, build an
1112 -- assignment for the corresponding field values. The flag U_U
1113 -- signals the presence of an Unchecked_Union and forces the usage
1114 -- of the inferred discriminant value of C as the right hand side
1115 -- of the assignment.
1117 function Make_Field_Assigns (CI : List_Id) return List_Id;
1118 -- Given CI, a component items list, construct series of statements
1119 -- for fieldwise assignment of the corresponding components.
1121 --------------------
1122 -- Find_Component --
1123 --------------------
1125 function Find_Component
1127 Comp : Entity_Id) return Entity_Id
1129 Utyp : constant Entity_Id := Underlying_Type (Typ);
1133 C := First_Entity (Utyp);
1135 while Present (C) loop
1136 if Chars (C) = Chars (Comp) then
1142 raise Program_Error;
1145 --------------------------------
1146 -- Make_Component_List_Assign --
1147 --------------------------------
1149 function Make_Component_List_Assign
1151 U_U : Boolean := False) return List_Id
1153 CI : constant List_Id := Component_Items (CL);
1154 VP : constant Node_Id := Variant_Part (CL);
1164 Result := Make_Field_Assigns (CI);
1166 if Present (VP) then
1168 V := First_Non_Pragma (Variants (VP));
1170 while Present (V) loop
1173 DC := First (Discrete_Choices (V));
1174 while Present (DC) loop
1175 Append_To (DCH, New_Copy_Tree (DC));
1180 Make_Case_Statement_Alternative (Loc,
1181 Discrete_Choices => DCH,
1183 Make_Component_List_Assign (Component_List (V))));
1184 Next_Non_Pragma (V);
1187 -- If we have an Unchecked_Union, use the value of the inferred
1188 -- discriminant of the variant part expression as the switch
1189 -- for the case statement. The case statement may later be
1194 New_Copy (Get_Discriminant_Value (
1197 Discriminant_Constraint (Etype (Rhs))));
1200 Make_Selected_Component (Loc,
1201 Prefix => Duplicate_Subexpr (Rhs),
1203 Make_Identifier (Loc, Chars (Name (VP))));
1207 Make_Case_Statement (Loc,
1209 Alternatives => Alts));
1213 end Make_Component_List_Assign;
1215 -----------------------
1216 -- Make_Field_Assign --
1217 -----------------------
1219 function Make_Field_Assign
1221 U_U : Boolean := False) return Node_Id
1227 -- In the case of an Unchecked_Union, use the discriminant
1228 -- constraint value as on the right hand side of the assignment.
1232 New_Copy (Get_Discriminant_Value (C,
1234 Discriminant_Constraint (Etype (Rhs))));
1237 Make_Selected_Component (Loc,
1238 Prefix => Duplicate_Subexpr (Rhs),
1239 Selector_Name => New_Occurrence_Of (C, Loc));
1243 Make_Assignment_Statement (Loc,
1245 Make_Selected_Component (Loc,
1246 Prefix => Duplicate_Subexpr (Lhs),
1248 New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
1249 Expression => Expr);
1251 -- Set Assignment_OK, so discriminants can be assigned
1253 Set_Assignment_OK (Name (A), True);
1255 end Make_Field_Assign;
1257 ------------------------
1258 -- Make_Field_Assigns --
1259 ------------------------
1261 function Make_Field_Assigns (CI : List_Id) return List_Id is
1268 while Present (Item) loop
1269 if Nkind (Item) = N_Component_Declaration then
1271 (Result, Make_Field_Assign (Defining_Identifier (Item)));
1278 end Make_Field_Assigns;
1280 -- Start of processing for Expand_Assign_Record
1283 -- Note that we use the base types for this processing. This results
1284 -- in some extra work in the constrained case, but the change of
1285 -- representation case is so unusual that it is not worth the effort.
1287 -- First copy the discriminants. This is done unconditionally. It
1288 -- is required in the unconstrained left side case, and also in the
1289 -- case where this assignment was constructed during the expansion
1290 -- of a type conversion (since initialization of discriminants is
1291 -- suppressed in this case). It is unnecessary but harmless in
1294 if Has_Discriminants (L_Typ) then
1295 F := First_Discriminant (R_Typ);
1296 while Present (F) loop
1298 if Is_Unchecked_Union (Base_Type (R_Typ)) then
1299 Insert_Action (N, Make_Field_Assign (F, True));
1301 Insert_Action (N, Make_Field_Assign (F));
1304 Next_Discriminant (F);
1308 -- We know the underlying type is a record, but its current view
1309 -- may be private. We must retrieve the usable record declaration.
1311 if Nkind (Decl) = N_Private_Type_Declaration
1312 and then Present (Full_View (R_Typ))
1314 RDef := Type_Definition (Declaration_Node (Full_View (R_Typ)));
1316 RDef := Type_Definition (Decl);
1319 if Nkind (RDef) = N_Record_Definition
1320 and then Present (Component_List (RDef))
1323 if Is_Unchecked_Union (R_Typ) then
1325 Make_Component_List_Assign (Component_List (RDef), True));
1328 (N, Make_Component_List_Assign (Component_List (RDef)));
1331 Rewrite (N, Make_Null_Statement (Loc));
1335 end Expand_Assign_Record;
1337 -----------------------------------
1338 -- Expand_N_Assignment_Statement --
1339 -----------------------------------
1341 -- For array types, deal with slice assignments and setting the flags
1342 -- to indicate if it can be statically determined which direction the
1343 -- move should go in. Also deal with generating range/length checks.
1345 procedure Expand_N_Assignment_Statement (N : Node_Id) is
1346 Loc : constant Source_Ptr := Sloc (N);
1347 Lhs : constant Node_Id := Name (N);
1348 Rhs : constant Node_Id := Expression (N);
1349 Typ : constant Entity_Id := Underlying_Type (Etype (Lhs));
1353 -- First deal with generation of range check if required. For now
1354 -- we do this only for discrete types.
1356 if Do_Range_Check (Rhs)
1357 and then Is_Discrete_Type (Typ)
1359 Set_Do_Range_Check (Rhs, False);
1360 Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed);
1363 -- Check for a special case where a high level transformation is
1364 -- required. If we have either of:
1369 -- where P is a reference to a bit packed array, then we have to unwind
1370 -- the assignment. The exact meaning of being a reference to a bit
1371 -- packed array is as follows:
1373 -- An indexed component whose prefix is a bit packed array is a
1374 -- reference to a bit packed array.
1376 -- An indexed component or selected component whose prefix is a
1377 -- reference to a bit packed array is itself a reference ot a
1378 -- bit packed array.
1380 -- The required transformation is
1382 -- Tnn : prefix_type := P;
1383 -- Tnn.field := rhs;
1388 -- Tnn : prefix_type := P;
1389 -- Tnn (subscr) := rhs;
1392 -- Since P is going to be evaluated more than once, any subscripts
1393 -- in P must have their evaluation forced.
1395 if (Nkind (Lhs) = N_Indexed_Component
1397 Nkind (Lhs) = N_Selected_Component)
1398 and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs))
1401 BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs));
1402 BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr);
1403 Tnn : constant Entity_Id :=
1404 Make_Defining_Identifier (Loc,
1405 Chars => New_Internal_Name ('T'));
1408 -- Insert the post assignment first, because we want to copy
1409 -- the BPAR_Expr tree before it gets analyzed in the context
1410 -- of the pre assignment. Note that we do not analyze the
1411 -- post assignment yet (we cannot till we have completed the
1412 -- analysis of the pre assignment). As usual, the analysis
1413 -- of this post assignment will happen on its own when we
1414 -- "run into" it after finishing the current assignment.
1417 Make_Assignment_Statement (Loc,
1418 Name => New_Copy_Tree (BPAR_Expr),
1419 Expression => New_Occurrence_Of (Tnn, Loc)));
1421 -- At this stage BPAR_Expr is a reference to a bit packed
1422 -- array where the reference was not expanded in the original
1423 -- tree, since it was on the left side of an assignment. But
1424 -- in the pre-assignment statement (the object definition),
1425 -- BPAR_Expr will end up on the right hand side, and must be
1426 -- reexpanded. To achieve this, we reset the analyzed flag
1427 -- of all selected and indexed components down to the actual
1428 -- indexed component for the packed array.
1432 Set_Analyzed (Exp, False);
1434 if Nkind (Exp) = N_Selected_Component
1436 Nkind (Exp) = N_Indexed_Component
1438 Exp := Prefix (Exp);
1444 -- Now we can insert and analyze the pre-assignment.
1446 -- If the right-hand side requires a transient scope, it has
1447 -- already been placed on the stack. However, the declaration is
1448 -- inserted in the tree outside of this scope, and must reflect
1449 -- the proper scope for its variable. This awkward bit is forced
1450 -- by the stricter scope discipline imposed by GCC 2.97.
1453 Uses_Transient_Scope : constant Boolean :=
1454 Scope_Is_Transient and then N = Node_To_Be_Wrapped;
1457 if Uses_Transient_Scope then
1458 New_Scope (Scope (Current_Scope));
1461 Insert_Before_And_Analyze (N,
1462 Make_Object_Declaration (Loc,
1463 Defining_Identifier => Tnn,
1464 Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc),
1465 Expression => BPAR_Expr));
1467 if Uses_Transient_Scope then
1472 -- Now fix up the original assignment and continue processing
1474 Rewrite (Prefix (Lhs),
1475 New_Occurrence_Of (Tnn, Loc));
1477 -- We do not need to reanalyze that assignment, and we do not need
1478 -- to worry about references to the temporary, but we do need to
1479 -- make sure that the temporary is not marked as a true constant
1480 -- since we now have a generate assignment to it!
1482 Set_Is_True_Constant (Tnn, False);
1486 -- When we have the appropriate type of aggregate in the
1487 -- expression (it has been determined during analysis of the
1488 -- aggregate by setting the delay flag), let's perform in place
1489 -- assignment and thus avoid creating a temporay.
1491 if Is_Delayed_Aggregate (Rhs) then
1492 Convert_Aggr_In_Assignment (N);
1493 Rewrite (N, Make_Null_Statement (Loc));
1498 -- Apply discriminant check if required. If Lhs is an access type
1499 -- to a designated type with discriminants, we must always check.
1501 if Has_Discriminants (Etype (Lhs)) then
1503 -- Skip discriminant check if change of representation. Will be
1504 -- done when the change of representation is expanded out.
1506 if not Change_Of_Representation (N) then
1507 Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs);
1510 -- If the type is private without discriminants, and the full type
1511 -- has discriminants (necessarily with defaults) a check may still be
1512 -- necessary if the Lhs is aliased. The private determinants must be
1513 -- visible to build the discriminant constraints.
1515 -- Only an explicit dereference that comes from source indicates
1516 -- aliasing. Access to formals of protected operations and entries
1517 -- create dereferences but are not semantic aliasings.
1519 elsif Is_Private_Type (Etype (Lhs))
1520 and then Has_Discriminants (Typ)
1521 and then Nkind (Lhs) = N_Explicit_Dereference
1522 and then Comes_From_Source (Lhs)
1525 Lt : constant Entity_Id := Etype (Lhs);
1527 Set_Etype (Lhs, Typ);
1528 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1529 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1530 Set_Etype (Lhs, Lt);
1533 -- If the Lhs has a private type with unknown discriminants, it
1534 -- may have a full view with discriminants, but those are nameable
1535 -- only in the underlying type, so convert the Rhs to it before
1536 -- potential checking.
1538 elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs)))
1539 and then Has_Discriminants (Typ)
1541 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1542 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1544 -- In the access type case, we need the same discriminant check,
1545 -- and also range checks if we have an access to constrained array.
1547 elsif Is_Access_Type (Etype (Lhs))
1548 and then Is_Constrained (Designated_Type (Etype (Lhs)))
1550 if Has_Discriminants (Designated_Type (Etype (Lhs))) then
1552 -- Skip discriminant check if change of representation. Will be
1553 -- done when the change of representation is expanded out.
1555 if not Change_Of_Representation (N) then
1556 Apply_Discriminant_Check (Rhs, Etype (Lhs));
1559 elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then
1560 Apply_Range_Check (Rhs, Etype (Lhs));
1562 if Is_Constrained (Etype (Lhs)) then
1563 Apply_Length_Check (Rhs, Etype (Lhs));
1566 if Nkind (Rhs) = N_Allocator then
1568 Target_Typ : constant Entity_Id := Etype (Expression (Rhs));
1569 C_Es : Check_Result;
1576 Etype (Designated_Type (Etype (Lhs))));
1588 -- Apply range check for access type case
1590 elsif Is_Access_Type (Etype (Lhs))
1591 and then Nkind (Rhs) = N_Allocator
1592 and then Nkind (Expression (Rhs)) = N_Qualified_Expression
1594 Analyze_And_Resolve (Expression (Rhs));
1596 (Expression (Rhs), Designated_Type (Etype (Lhs)));
1599 -- Ada 2005 (AI-231): Generate conversion to the null-excluding
1600 -- type to force the corresponding run-time check
1602 if Is_Access_Type (Typ)
1604 ((Is_Entity_Name (Lhs) and then Can_Never_Be_Null (Entity (Lhs)))
1605 or else Can_Never_Be_Null (Etype (Lhs)))
1607 Rewrite (Rhs, Convert_To (Etype (Lhs),
1608 Relocate_Node (Rhs)));
1609 Analyze_And_Resolve (Rhs, Etype (Lhs));
1612 -- If we are assigning an access type and the left side is an
1613 -- entity, then make sure that Is_Known_Non_Null properly
1614 -- reflects the state of the entity after the assignment
1616 if Is_Access_Type (Typ)
1617 and then Is_Entity_Name (Lhs)
1618 and then Known_Non_Null (Rhs)
1619 and then Safe_To_Capture_Value (N, Entity (Lhs))
1621 Set_Is_Known_Non_Null (Entity (Lhs), Known_Non_Null (Rhs));
1624 -- Case of assignment to a bit packed array element
1626 if Nkind (Lhs) = N_Indexed_Component
1627 and then Is_Bit_Packed_Array (Etype (Prefix (Lhs)))
1629 Expand_Bit_Packed_Element_Set (N);
1632 -- Case of tagged type assignment
1634 elsif Is_Tagged_Type (Typ)
1635 or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ))
1637 Tagged_Case : declare
1638 L : List_Id := No_List;
1639 Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N);
1642 -- In the controlled case, we need to make sure that function
1643 -- calls are evaluated before finalizing the target. In all
1644 -- cases, it makes the expansion easier if the side-effects
1645 -- are removed first.
1647 Remove_Side_Effects (Lhs);
1648 Remove_Side_Effects (Rhs);
1650 -- Avoid recursion in the mechanism
1654 -- If dispatching assignment, we need to dispatch to _assign
1656 if Is_Class_Wide_Type (Typ)
1658 -- If the type is tagged, we may as well use the predefined
1659 -- primitive assignment. This avoids inlining a lot of code
1660 -- and in the class-wide case, the assignment is replaced by
1661 -- a dispatch call to _assign. Note that this cannot be done
1662 -- when discriminant checks are locally suppressed (as in
1663 -- extension aggregate expansions) because otherwise the
1664 -- discriminant check will be performed within the _assign
1667 or else (Is_Tagged_Type (Typ)
1668 and then Chars (Current_Scope) /= Name_uAssign
1669 and then Expand_Ctrl_Actions
1670 and then not Discriminant_Checks_Suppressed (Empty))
1672 -- Fetch the primitive op _assign and proper type to call
1673 -- it. Because of possible conflits between private and
1674 -- full view the proper type is fetched directly from the
1675 -- operation profile.
1678 Op : constant Entity_Id :=
1679 Find_Prim_Op (Typ, Name_uAssign);
1680 F_Typ : Entity_Id := Etype (First_Formal (Op));
1683 -- If the assignment is dispatching, make sure to use the
1684 -- ??? where is rest of this comment ???
1686 if Is_Class_Wide_Type (Typ) then
1687 F_Typ := Class_Wide_Type (F_Typ);
1691 Make_Procedure_Call_Statement (Loc,
1692 Name => New_Reference_To (Op, Loc),
1693 Parameter_Associations => New_List (
1694 Unchecked_Convert_To (F_Typ, Duplicate_Subexpr (Lhs)),
1695 Unchecked_Convert_To (F_Typ,
1696 Duplicate_Subexpr (Rhs)))));
1700 L := Make_Tag_Ctrl_Assignment (N);
1702 -- We can't afford to have destructive Finalization Actions
1703 -- in the Self assignment case, so if the target and the
1704 -- source are not obviously different, code is generated to
1705 -- avoid the self assignment case
1707 -- if lhs'address /= rhs'address then
1708 -- <code for controlled and/or tagged assignment>
1711 if not Statically_Different (Lhs, Rhs)
1712 and then Expand_Ctrl_Actions
1715 Make_Implicit_If_Statement (N,
1719 Make_Attribute_Reference (Loc,
1720 Prefix => Duplicate_Subexpr (Lhs),
1721 Attribute_Name => Name_Address),
1724 Make_Attribute_Reference (Loc,
1725 Prefix => Duplicate_Subexpr (Rhs),
1726 Attribute_Name => Name_Address)),
1728 Then_Statements => L));
1731 -- We need to set up an exception handler for implementing
1732 -- 7.6.1 (18). The remaining adjustments are tackled by the
1733 -- implementation of adjust for record_controllers (see
1736 -- This is skipped if we have no finalization
1738 if Expand_Ctrl_Actions
1739 and then not Restriction_Active (No_Finalization)
1742 Make_Block_Statement (Loc,
1743 Handled_Statement_Sequence =>
1744 Make_Handled_Sequence_Of_Statements (Loc,
1746 Exception_Handlers => New_List (
1747 Make_Exception_Handler (Loc,
1748 Exception_Choices =>
1749 New_List (Make_Others_Choice (Loc)),
1750 Statements => New_List (
1751 Make_Raise_Program_Error (Loc,
1753 PE_Finalize_Raised_Exception)
1759 Make_Block_Statement (Loc,
1760 Handled_Statement_Sequence =>
1761 Make_Handled_Sequence_Of_Statements (Loc, Statements => L)));
1763 -- If no restrictions on aborts, protect the whole assignement
1764 -- for controlled objects as per 9.8(11)
1766 if Controlled_Type (Typ)
1767 and then Expand_Ctrl_Actions
1768 and then Abort_Allowed
1771 Blk : constant Entity_Id :=
1772 New_Internal_Entity (
1773 E_Block, Current_Scope, Sloc (N), 'B');
1776 Set_Scope (Blk, Current_Scope);
1777 Set_Etype (Blk, Standard_Void_Type);
1778 Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N)));
1780 Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer));
1781 Set_At_End_Proc (Handled_Statement_Sequence (N),
1782 New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc));
1783 Expand_At_End_Handler
1784 (Handled_Statement_Sequence (N), Blk);
1794 elsif Is_Array_Type (Typ) then
1796 Actual_Rhs : Node_Id := Rhs;
1799 while Nkind (Actual_Rhs) = N_Type_Conversion
1801 Nkind (Actual_Rhs) = N_Qualified_Expression
1803 Actual_Rhs := Expression (Actual_Rhs);
1806 Expand_Assign_Array (N, Actual_Rhs);
1812 elsif Is_Record_Type (Typ) then
1813 Expand_Assign_Record (N);
1816 -- Scalar types. This is where we perform the processing related
1817 -- to the requirements of (RM 13.9.1(9-11)) concerning the handling
1818 -- of invalid scalar values.
1820 elsif Is_Scalar_Type (Typ) then
1822 -- Case where right side is known valid
1824 if Expr_Known_Valid (Rhs) then
1826 -- Here the right side is valid, so it is fine. The case to
1827 -- deal with is when the left side is a local variable reference
1828 -- whose value is not currently known to be valid. If this is
1829 -- the case, and the assignment appears in an unconditional
1830 -- context, then we can mark the left side as now being valid.
1832 if Is_Local_Variable_Reference (Lhs)
1833 and then not Is_Known_Valid (Entity (Lhs))
1834 and then In_Unconditional_Context (N)
1836 Set_Is_Known_Valid (Entity (Lhs), True);
1839 -- Case where right side may be invalid in the sense of the RM
1840 -- reference above. The RM does not require that we check for
1841 -- the validity on an assignment, but it does require that the
1842 -- assignment of an invalid value not cause erroneous behavior.
1844 -- The general approach in GNAT is to use the Is_Known_Valid flag
1845 -- to avoid the need for validity checking on assignments. However
1846 -- in some cases, we have to do validity checking in order to make
1847 -- sure that the setting of this flag is correct.
1850 -- Validate right side if we are validating copies
1852 if Validity_Checks_On
1853 and then Validity_Check_Copies
1857 -- We can propagate this to the left side where appropriate
1859 if Is_Local_Variable_Reference (Lhs)
1860 and then not Is_Known_Valid (Entity (Lhs))
1861 and then In_Unconditional_Context (N)
1863 Set_Is_Known_Valid (Entity (Lhs), True);
1866 -- Otherwise check to see what should be done
1868 -- If left side is a local variable, then we just set its
1869 -- flag to indicate that its value may no longer be valid,
1870 -- since we are copying a potentially invalid value.
1872 elsif Is_Local_Variable_Reference (Lhs) then
1873 Set_Is_Known_Valid (Entity (Lhs), False);
1875 -- Check for case of a nonlocal variable on the left side
1876 -- which is currently known to be valid. In this case, we
1877 -- simply ensure that the right side is valid. We only play
1878 -- the game of copying validity status for local variables,
1879 -- since we are doing this statically, not by tracing the
1882 elsif Is_Entity_Name (Lhs)
1883 and then Is_Known_Valid (Entity (Lhs))
1885 -- Note that the Ensure_Valid call is ignored if the
1886 -- Validity_Checking mode is set to none so we do not
1887 -- need to worry about that case here.
1891 -- In all other cases, we can safely copy an invalid value
1892 -- without worrying about the status of the left side. Since
1893 -- it is not a variable reference it will not be considered
1894 -- as being known to be valid in any case.
1902 -- Defend against invalid subscripts on left side if we are in
1903 -- standard validity checking mode. No need to do this if we
1904 -- are checking all subscripts.
1906 if Validity_Checks_On
1907 and then Validity_Check_Default
1908 and then not Validity_Check_Subscripts
1910 Check_Valid_Lvalue_Subscripts (Lhs);
1914 when RE_Not_Available =>
1916 end Expand_N_Assignment_Statement;
1918 ------------------------------
1919 -- Expand_N_Block_Statement --
1920 ------------------------------
1922 -- Encode entity names defined in block statement
1924 procedure Expand_N_Block_Statement (N : Node_Id) is
1926 Qualify_Entity_Names (N);
1927 end Expand_N_Block_Statement;
1929 -----------------------------
1930 -- Expand_N_Case_Statement --
1931 -----------------------------
1933 procedure Expand_N_Case_Statement (N : Node_Id) is
1934 Loc : constant Source_Ptr := Sloc (N);
1935 Expr : constant Node_Id := Expression (N);
1943 -- Check for the situation where we know at compile time which
1944 -- branch will be taken
1946 if Compile_Time_Known_Value (Expr) then
1947 Alt := Find_Static_Alternative (N);
1949 -- Move the statements from this alternative after the case
1950 -- statement. They are already analyzed, so will be skipped
1953 Insert_List_After (N, Statements (Alt));
1955 -- That leaves the case statement as a shell. The alternative
1956 -- that will be executed is reset to a null list. So now we can
1957 -- kill the entire case statement.
1959 Kill_Dead_Code (Expression (N));
1960 Kill_Dead_Code (Alternatives (N));
1961 Rewrite (N, Make_Null_Statement (Loc));
1965 -- Here if the choice is not determined at compile time
1968 Last_Alt : constant Node_Id := Last (Alternatives (N));
1970 Others_Present : Boolean;
1971 Others_Node : Node_Id;
1973 Then_Stms : List_Id;
1974 Else_Stms : List_Id;
1977 if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then
1978 Others_Present := True;
1979 Others_Node := Last_Alt;
1981 Others_Present := False;
1984 -- First step is to worry about possible invalid argument. The RM
1985 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
1986 -- outside the base range), then Constraint_Error must be raised.
1988 -- Case of validity check required (validity checks are on, the
1989 -- expression is not known to be valid, and the case statement
1990 -- comes from source -- no need to validity check internally
1991 -- generated case statements).
1993 if Validity_Check_Default then
1994 Ensure_Valid (Expr);
1997 -- If there is only a single alternative, just replace it with
1998 -- the sequence of statements since obviously that is what is
1999 -- going to be executed in all cases.
2001 Len := List_Length (Alternatives (N));
2004 -- We still need to evaluate the expression if it has any
2007 Remove_Side_Effects (Expression (N));
2009 Insert_List_After (N, Statements (First (Alternatives (N))));
2011 -- That leaves the case statement as a shell. The alternative
2012 -- that will be executed is reset to a null list. So now we can
2013 -- kill the entire case statement.
2015 Kill_Dead_Code (Expression (N));
2016 Rewrite (N, Make_Null_Statement (Loc));
2020 -- An optimization. If there are only two alternatives, and only
2021 -- a single choice, then rewrite the whole case statement as an
2022 -- if statement, since this can result in susbequent optimizations.
2023 -- This helps not only with case statements in the source of a
2024 -- simple form, but also with generated code (discriminant check
2025 -- functions in particular)
2028 Chlist := Discrete_Choices (First (Alternatives (N)));
2030 if List_Length (Chlist) = 1 then
2031 Choice := First (Chlist);
2033 Then_Stms := Statements (First (Alternatives (N)));
2034 Else_Stms := Statements (Last (Alternatives (N)));
2036 -- For TRUE, generate "expression", not expression = true
2038 if Nkind (Choice) = N_Identifier
2039 and then Entity (Choice) = Standard_True
2041 Cond := Expression (N);
2043 -- For FALSE, generate "expression" and switch then/else
2045 elsif Nkind (Choice) = N_Identifier
2046 and then Entity (Choice) = Standard_False
2048 Cond := Expression (N);
2049 Else_Stms := Statements (First (Alternatives (N)));
2050 Then_Stms := Statements (Last (Alternatives (N)));
2052 -- For a range, generate "expression in range"
2054 elsif Nkind (Choice) = N_Range
2055 or else (Nkind (Choice) = N_Attribute_Reference
2056 and then Attribute_Name (Choice) = Name_Range)
2057 or else (Is_Entity_Name (Choice)
2058 and then Is_Type (Entity (Choice)))
2059 or else Nkind (Choice) = N_Subtype_Indication
2063 Left_Opnd => Expression (N),
2064 Right_Opnd => Relocate_Node (Choice));
2066 -- For any other subexpression "expression = value"
2071 Left_Opnd => Expression (N),
2072 Right_Opnd => Relocate_Node (Choice));
2075 -- Now rewrite the case as an IF
2078 Make_If_Statement (Loc,
2080 Then_Statements => Then_Stms,
2081 Else_Statements => Else_Stms));
2087 -- If the last alternative is not an Others choice, replace it
2088 -- with an N_Others_Choice. Note that we do not bother to call
2089 -- Analyze on the modified case statement, since it's only effect
2090 -- would be to compute the contents of the Others_Discrete_Choices
2091 -- which is not needed by the back end anyway.
2093 -- The reason we do this is that the back end always needs some
2094 -- default for a switch, so if we have not supplied one in the
2095 -- processing above for validity checking, then we need to
2098 if not Others_Present then
2099 Others_Node := Make_Others_Choice (Sloc (Last_Alt));
2100 Set_Others_Discrete_Choices
2101 (Others_Node, Discrete_Choices (Last_Alt));
2102 Set_Discrete_Choices (Last_Alt, New_List (Others_Node));
2105 end Expand_N_Case_Statement;
2107 -----------------------------
2108 -- Expand_N_Exit_Statement --
2109 -----------------------------
2111 -- The only processing required is to deal with a possible C/Fortran
2112 -- boolean value used as the condition for the exit statement.
2114 procedure Expand_N_Exit_Statement (N : Node_Id) is
2116 Adjust_Condition (Condition (N));
2117 end Expand_N_Exit_Statement;
2119 -----------------------------
2120 -- Expand_N_Goto_Statement --
2121 -----------------------------
2123 -- Add poll before goto if polling active
2125 procedure Expand_N_Goto_Statement (N : Node_Id) is
2127 Generate_Poll_Call (N);
2128 end Expand_N_Goto_Statement;
2130 ---------------------------
2131 -- Expand_N_If_Statement --
2132 ---------------------------
2134 -- First we deal with the case of C and Fortran convention boolean
2135 -- values, with zero/non-zero semantics.
2137 -- Second, we deal with the obvious rewriting for the cases where the
2138 -- condition of the IF is known at compile time to be True or False.
2140 -- Third, we remove elsif parts which have non-empty Condition_Actions
2141 -- and rewrite as independent if statements. For example:
2152 -- <<condition actions of y>>
2158 -- This rewriting is needed if at least one elsif part has a non-empty
2159 -- Condition_Actions list. We also do the same processing if there is
2160 -- a constant condition in an elsif part (in conjunction with the first
2161 -- processing step mentioned above, for the recursive call made to deal
2162 -- with the created inner if, this deals with properly optimizing the
2163 -- cases of constant elsif conditions).
2165 procedure Expand_N_If_Statement (N : Node_Id) is
2166 Loc : constant Source_Ptr := Sloc (N);
2172 Adjust_Condition (Condition (N));
2174 -- The following loop deals with constant conditions for the IF. We
2175 -- need a loop because as we eliminate False conditions, we grab the
2176 -- first elsif condition and use it as the primary condition.
2178 while Compile_Time_Known_Value (Condition (N)) loop
2180 -- If condition is True, we can simply rewrite the if statement
2181 -- now by replacing it by the series of then statements.
2183 if Is_True (Expr_Value (Condition (N))) then
2185 -- All the else parts can be killed
2187 Kill_Dead_Code (Elsif_Parts (N));
2188 Kill_Dead_Code (Else_Statements (N));
2190 Hed := Remove_Head (Then_Statements (N));
2191 Insert_List_After (N, Then_Statements (N));
2195 -- If condition is False, then we can delete the condition and
2196 -- the Then statements
2199 -- We do not delete the condition if constant condition
2200 -- warnings are enabled, since otherwise we end up deleting
2201 -- the desired warning. Of course the backend will get rid
2202 -- of this True/False test anyway, so nothing is lost here.
2204 if not Constant_Condition_Warnings then
2205 Kill_Dead_Code (Condition (N));
2208 Kill_Dead_Code (Then_Statements (N));
2210 -- If there are no elsif statements, then we simply replace
2211 -- the entire if statement by the sequence of else statements.
2213 if No (Elsif_Parts (N)) then
2215 if No (Else_Statements (N))
2216 or else Is_Empty_List (Else_Statements (N))
2219 Make_Null_Statement (Sloc (N)));
2222 Hed := Remove_Head (Else_Statements (N));
2223 Insert_List_After (N, Else_Statements (N));
2229 -- If there are elsif statements, the first of them becomes
2230 -- the if/then section of the rebuilt if statement This is
2231 -- the case where we loop to reprocess this copied condition.
2234 Hed := Remove_Head (Elsif_Parts (N));
2235 Insert_Actions (N, Condition_Actions (Hed));
2236 Set_Condition (N, Condition (Hed));
2237 Set_Then_Statements (N, Then_Statements (Hed));
2239 if Is_Empty_List (Elsif_Parts (N)) then
2240 Set_Elsif_Parts (N, No_List);
2246 -- Loop through elsif parts, dealing with constant conditions and
2247 -- possible expression actions that are present.
2249 if Present (Elsif_Parts (N)) then
2250 E := First (Elsif_Parts (N));
2251 while Present (E) loop
2252 Adjust_Condition (Condition (E));
2254 -- If there are condition actions, then we rewrite the if
2255 -- statement as indicated above. We also do the same rewrite
2256 -- if the condition is True or False. The further processing
2257 -- of this constant condition is then done by the recursive
2258 -- call to expand the newly created if statement
2260 if Present (Condition_Actions (E))
2261 or else Compile_Time_Known_Value (Condition (E))
2263 -- Note this is not an implicit if statement, since it is
2264 -- part of an explicit if statement in the source (or of an
2265 -- implicit if statement that has already been tested).
2268 Make_If_Statement (Sloc (E),
2269 Condition => Condition (E),
2270 Then_Statements => Then_Statements (E),
2271 Elsif_Parts => No_List,
2272 Else_Statements => Else_Statements (N));
2274 -- Elsif parts for new if come from remaining elsif's of parent
2276 while Present (Next (E)) loop
2277 if No (Elsif_Parts (New_If)) then
2278 Set_Elsif_Parts (New_If, New_List);
2281 Append (Remove_Next (E), Elsif_Parts (New_If));
2284 Set_Else_Statements (N, New_List (New_If));
2286 if Present (Condition_Actions (E)) then
2287 Insert_List_Before (New_If, Condition_Actions (E));
2292 if Is_Empty_List (Elsif_Parts (N)) then
2293 Set_Elsif_Parts (N, No_List);
2299 -- No special processing for that elsif part, move to next
2307 -- Some more optimizations applicable if we still have an IF statement
2309 if Nkind (N) /= N_If_Statement then
2313 -- Another optimization, special cases that can be simplified
2315 -- if expression then
2321 -- can be changed to:
2323 -- return expression;
2327 -- if expression then
2333 -- can be changed to:
2335 -- return not (expression);
2337 if Nkind (N) = N_If_Statement
2338 and then No (Elsif_Parts (N))
2339 and then Present (Else_Statements (N))
2340 and then List_Length (Then_Statements (N)) = 1
2341 and then List_Length (Else_Statements (N)) = 1
2344 Then_Stm : constant Node_Id := First (Then_Statements (N));
2345 Else_Stm : constant Node_Id := First (Else_Statements (N));
2348 if Nkind (Then_Stm) = N_Return_Statement
2350 Nkind (Else_Stm) = N_Return_Statement
2353 Then_Expr : constant Node_Id := Expression (Then_Stm);
2354 Else_Expr : constant Node_Id := Expression (Else_Stm);
2357 if Nkind (Then_Expr) = N_Identifier
2359 Nkind (Else_Expr) = N_Identifier
2361 if Entity (Then_Expr) = Standard_True
2362 and then Entity (Else_Expr) = Standard_False
2365 Make_Return_Statement (Loc,
2366 Expression => Relocate_Node (Condition (N))));
2370 elsif Entity (Then_Expr) = Standard_False
2371 and then Entity (Else_Expr) = Standard_True
2374 Make_Return_Statement (Loc,
2377 Right_Opnd => Relocate_Node (Condition (N)))));
2386 end Expand_N_If_Statement;
2388 -----------------------------
2389 -- Expand_N_Loop_Statement --
2390 -----------------------------
2392 -- 1. Deal with while condition for C/Fortran boolean
2393 -- 2. Deal with loops with a non-standard enumeration type range
2394 -- 3. Deal with while loops where Condition_Actions is set
2395 -- 4. Insert polling call if required
2397 procedure Expand_N_Loop_Statement (N : Node_Id) is
2398 Loc : constant Source_Ptr := Sloc (N);
2399 Isc : constant Node_Id := Iteration_Scheme (N);
2402 if Present (Isc) then
2403 Adjust_Condition (Condition (Isc));
2406 if Is_Non_Empty_List (Statements (N)) then
2407 Generate_Poll_Call (First (Statements (N)));
2414 -- Handle the case where we have a for loop with the range type being
2415 -- an enumeration type with non-standard representation. In this case
2418 -- for x in [reverse] a .. b loop
2424 -- for xP in [reverse] integer
2425 -- range etype'Pos (a) .. etype'Pos (b) loop
2427 -- x : constant etype := Pos_To_Rep (xP);
2433 if Present (Loop_Parameter_Specification (Isc)) then
2435 LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
2436 Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
2437 Ltype : constant Entity_Id := Etype (Loop_Id);
2438 Btype : constant Entity_Id := Base_Type (Ltype);
2443 if not Is_Enumeration_Type (Btype)
2444 or else No (Enum_Pos_To_Rep (Btype))
2450 Make_Defining_Identifier (Loc,
2451 Chars => New_External_Name (Chars (Loop_Id), 'P'));
2453 -- If the type has a contiguous representation, successive
2454 -- values can be generated as offsets from the first literal.
2456 if Has_Contiguous_Rep (Btype) then
2458 Unchecked_Convert_To (Btype,
2461 Make_Integer_Literal (Loc,
2462 Enumeration_Rep (First_Literal (Btype))),
2463 Right_Opnd => New_Reference_To (New_Id, Loc)));
2465 -- Use the constructed array Enum_Pos_To_Rep.
2468 Make_Indexed_Component (Loc,
2469 Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc),
2470 Expressions => New_List (New_Reference_To (New_Id, Loc)));
2474 Make_Loop_Statement (Loc,
2475 Identifier => Identifier (N),
2478 Make_Iteration_Scheme (Loc,
2479 Loop_Parameter_Specification =>
2480 Make_Loop_Parameter_Specification (Loc,
2481 Defining_Identifier => New_Id,
2482 Reverse_Present => Reverse_Present (LPS),
2484 Discrete_Subtype_Definition =>
2485 Make_Subtype_Indication (Loc,
2488 New_Reference_To (Standard_Natural, Loc),
2491 Make_Range_Constraint (Loc,
2496 Make_Attribute_Reference (Loc,
2498 New_Reference_To (Btype, Loc),
2500 Attribute_Name => Name_Pos,
2502 Expressions => New_List (
2504 (Type_Low_Bound (Ltype)))),
2507 Make_Attribute_Reference (Loc,
2509 New_Reference_To (Btype, Loc),
2511 Attribute_Name => Name_Pos,
2513 Expressions => New_List (
2515 (Type_High_Bound (Ltype))))))))),
2517 Statements => New_List (
2518 Make_Block_Statement (Loc,
2519 Declarations => New_List (
2520 Make_Object_Declaration (Loc,
2521 Defining_Identifier => Loop_Id,
2522 Constant_Present => True,
2523 Object_Definition => New_Reference_To (Ltype, Loc),
2524 Expression => Expr)),
2526 Handled_Statement_Sequence =>
2527 Make_Handled_Sequence_Of_Statements (Loc,
2528 Statements => Statements (N)))),
2530 End_Label => End_Label (N)));
2534 -- Second case, if we have a while loop with Condition_Actions set,
2535 -- then we change it into a plain loop:
2544 -- <<condition actions>>
2550 and then Present (Condition_Actions (Isc))
2557 Make_Exit_Statement (Sloc (Condition (Isc)),
2559 Make_Op_Not (Sloc (Condition (Isc)),
2560 Right_Opnd => Condition (Isc)));
2562 Prepend (ES, Statements (N));
2563 Insert_List_Before (ES, Condition_Actions (Isc));
2565 -- This is not an implicit loop, since it is generated in
2566 -- response to the loop statement being processed. If this
2567 -- is itself implicit, the restriction has already been
2568 -- checked. If not, it is an explicit loop.
2571 Make_Loop_Statement (Sloc (N),
2572 Identifier => Identifier (N),
2573 Statements => Statements (N),
2574 End_Label => End_Label (N)));
2579 end Expand_N_Loop_Statement;
2581 -------------------------------
2582 -- Expand_N_Return_Statement --
2583 -------------------------------
2585 procedure Expand_N_Return_Statement (N : Node_Id) is
2586 Loc : constant Source_Ptr := Sloc (N);
2587 Exp : constant Node_Id := Expression (N);
2591 Scope_Id : Entity_Id;
2595 Goto_Stat : Node_Id;
2598 Return_Type : Entity_Id;
2599 Result_Exp : Node_Id;
2600 Result_Id : Entity_Id;
2601 Result_Obj : Node_Id;
2604 -- Case where returned expression is present
2606 if Present (Exp) then
2608 -- Always normalize C/Fortran boolean result. This is not always
2609 -- necessary, but it seems a good idea to minimize the passing
2610 -- around of non-normalized values, and in any case this handles
2611 -- the processing of barrier functions for protected types, which
2612 -- turn the condition into a return statement.
2614 Exptyp := Etype (Exp);
2616 if Is_Boolean_Type (Exptyp)
2617 and then Nonzero_Is_True (Exptyp)
2619 Adjust_Condition (Exp);
2620 Adjust_Result_Type (Exp, Exptyp);
2623 -- Do validity check if enabled for returns
2625 if Validity_Checks_On
2626 and then Validity_Check_Returns
2632 -- Find relevant enclosing scope from which return is returning
2634 Cur_Idx := Scope_Stack.Last;
2636 Scope_Id := Scope_Stack.Table (Cur_Idx).Entity;
2638 if Ekind (Scope_Id) /= E_Block
2639 and then Ekind (Scope_Id) /= E_Loop
2644 Cur_Idx := Cur_Idx - 1;
2645 pragma Assert (Cur_Idx >= 0);
2650 Kind := Ekind (Scope_Id);
2652 -- If it is a return from procedures do no extra steps.
2654 if Kind = E_Procedure or else Kind = E_Generic_Procedure then
2658 pragma Assert (Is_Entry (Scope_Id));
2660 -- Look at the enclosing block to see whether the return is from
2661 -- an accept statement or an entry body.
2663 for J in reverse 0 .. Cur_Idx loop
2664 Scope_Id := Scope_Stack.Table (J).Entity;
2665 exit when Is_Concurrent_Type (Scope_Id);
2668 -- If it is a return from accept statement it should be expanded
2669 -- as a call to RTS Complete_Rendezvous and a goto to the end of
2672 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
2673 -- Expand_N_Accept_Alternative in exp_ch9.adb)
2675 if Is_Task_Type (Scope_Id) then
2677 Call := (Make_Procedure_Call_Statement (Loc,
2678 Name => New_Reference_To
2679 (RTE (RE_Complete_Rendezvous), Loc)));
2680 Insert_Before (N, Call);
2681 -- why not insert actions here???
2684 Acc_Stat := Parent (N);
2685 while Nkind (Acc_Stat) /= N_Accept_Statement loop
2686 Acc_Stat := Parent (Acc_Stat);
2689 Lab_Node := Last (Statements
2690 (Handled_Statement_Sequence (Acc_Stat)));
2692 Goto_Stat := Make_Goto_Statement (Loc,
2693 Name => New_Occurrence_Of
2694 (Entity (Identifier (Lab_Node)), Loc));
2696 Set_Analyzed (Goto_Stat);
2698 Rewrite (N, Goto_Stat);
2701 -- If it is a return from an entry body, put a Complete_Entry_Body
2702 -- call in front of the return.
2704 elsif Is_Protected_Type (Scope_Id) then
2707 Make_Procedure_Call_Statement (Loc,
2708 Name => New_Reference_To
2709 (RTE (RE_Complete_Entry_Body), Loc),
2710 Parameter_Associations => New_List
2711 (Make_Attribute_Reference (Loc,
2715 (Corresponding_Body (Parent (Scope_Id))),
2717 Attribute_Name => Name_Unchecked_Access)));
2719 Insert_Before (N, Call);
2728 Return_Type := Etype (Scope_Id);
2729 Utyp := Underlying_Type (Return_Type);
2731 -- Check the result expression of a scalar function against
2732 -- the subtype of the function by inserting a conversion.
2733 -- This conversion must eventually be performed for other
2734 -- classes of types, but for now it's only done for scalars.
2737 if Is_Scalar_Type (T) then
2738 Rewrite (Exp, Convert_To (Return_Type, Exp));
2742 -- Implement the rules of 6.5(8-10), which require a tag check in
2743 -- the case of a limited tagged return type, and tag reassignment
2744 -- for nonlimited tagged results. These actions are needed when
2745 -- the return type is a specific tagged type and the result
2746 -- expression is a conversion or a formal parameter, because in
2747 -- that case the tag of the expression might differ from the tag
2748 -- of the specific result type.
2750 if Is_Tagged_Type (Utyp)
2751 and then not Is_Class_Wide_Type (Utyp)
2752 and then (Nkind (Exp) = N_Type_Conversion
2753 or else Nkind (Exp) = N_Unchecked_Type_Conversion
2754 or else (Is_Entity_Name (Exp)
2755 and then Ekind (Entity (Exp)) in Formal_Kind))
2757 -- When the return type is limited, perform a check that the
2758 -- tag of the result is the same as the tag of the return type.
2760 if Is_Limited_Type (Return_Type) then
2762 Make_Raise_Constraint_Error (Loc,
2766 Make_Selected_Component (Loc,
2767 Prefix => Duplicate_Subexpr (Exp),
2769 New_Reference_To (Tag_Component (Utyp), Loc)),
2771 Unchecked_Convert_To (RTE (RE_Tag),
2773 (Access_Disp_Table (Base_Type (Utyp)), Loc))),
2774 Reason => CE_Tag_Check_Failed));
2776 -- If the result type is a specific nonlimited tagged type,
2777 -- then we have to ensure that the tag of the result is that
2778 -- of the result type. This is handled by making a copy of the
2779 -- expression in the case where it might have a different tag,
2780 -- namely when the expression is a conversion or a formal
2781 -- parameter. We create a new object of the result type and
2782 -- initialize it from the expression, which will implicitly
2783 -- force the tag to be set appropriately.
2787 Make_Defining_Identifier (Loc, New_Internal_Name ('R'));
2788 Result_Exp := New_Reference_To (Result_Id, Loc);
2791 Make_Object_Declaration (Loc,
2792 Defining_Identifier => Result_Id,
2793 Object_Definition => New_Reference_To (Return_Type, Loc),
2794 Constant_Present => True,
2795 Expression => Relocate_Node (Exp));
2797 Set_Assignment_OK (Result_Obj);
2798 Insert_Action (Exp, Result_Obj);
2800 Rewrite (Exp, Result_Exp);
2801 Analyze_And_Resolve (Exp, Return_Type);
2805 -- Deal with returning variable length objects and controlled types
2807 -- Nothing to do if we are returning by reference, or this is not
2808 -- a type that requires special processing (indicated by the fact
2809 -- that it requires a cleanup scope for the secondary stack case)
2811 if Is_Return_By_Reference_Type (T)
2812 or else not Requires_Transient_Scope (Return_Type)
2816 -- Case of secondary stack not used
2818 elsif Function_Returns_With_DSP (Scope_Id) then
2820 -- Here what we need to do is to always return by reference, since
2821 -- we will return with the stack pointer depressed. We may need to
2822 -- do a copy to a local temporary before doing this return.
2824 No_Secondary_Stack_Case : declare
2825 Local_Copy_Required : Boolean := False;
2826 -- Set to True if a local copy is required
2828 Copy_Ent : Entity_Id;
2829 -- Used for the target entity if a copy is required
2832 -- Declaration used to create copy if needed
2834 procedure Test_Copy_Required (Expr : Node_Id);
2835 -- Determines if Expr represents a return value for which a
2836 -- copy is required. More specifically, a copy is not required
2837 -- if Expr represents an object or component of an object that
2838 -- is either in the local subprogram frame, or is constant.
2839 -- If a copy is required, then Local_Copy_Required is set True.
2841 ------------------------
2842 -- Test_Copy_Required --
2843 ------------------------
2845 procedure Test_Copy_Required (Expr : Node_Id) is
2849 -- If component, test prefix (object containing component)
2851 if Nkind (Expr) = N_Indexed_Component
2853 Nkind (Expr) = N_Selected_Component
2855 Test_Copy_Required (Prefix (Expr));
2858 -- See if we have an entity name
2860 elsif Is_Entity_Name (Expr) then
2861 Ent := Entity (Expr);
2863 -- Constant entity is always OK, no copy required
2865 if Ekind (Ent) = E_Constant then
2868 -- No copy required for local variable
2870 elsif Ekind (Ent) = E_Variable
2871 and then Scope (Ent) = Current_Subprogram
2877 -- All other cases require a copy
2879 Local_Copy_Required := True;
2880 end Test_Copy_Required;
2882 -- Start of processing for No_Secondary_Stack_Case
2885 -- No copy needed if result is from a function call.
2886 -- In this case the result is already being returned by
2887 -- reference with the stack pointer depressed.
2889 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2890 -- the copy for array types if the constrained status of the
2891 -- target type is different from that of the expression.
2893 if Requires_Transient_Scope (T)
2895 (not Is_Array_Type (T)
2896 or else Is_Constrained (T) = Is_Constrained (Return_Type)
2897 or else Controlled_Type (T))
2898 and then Nkind (Exp) = N_Function_Call
2902 -- We always need a local copy for a controlled type, since
2903 -- we are required to finalize the local value before return.
2904 -- The copy will automatically include the required finalize.
2905 -- Moreover, gigi cannot make this copy, since we need special
2906 -- processing to ensure proper behavior for finalization.
2908 -- Note: the reason we are returning with a depressed stack
2909 -- pointer in the controlled case (even if the type involved
2910 -- is constrained) is that we must make a local copy to deal
2911 -- properly with the requirement that the local result be
2914 elsif Controlled_Type (Utyp) then
2916 Make_Defining_Identifier (Loc,
2917 Chars => New_Internal_Name ('R'));
2919 -- Build declaration to do the copy, and insert it, setting
2920 -- Assignment_OK, because we may be copying a limited type.
2921 -- In addition we set the special flag to inhibit finalize
2922 -- attachment if this is a controlled type (since this attach
2923 -- must be done by the caller, otherwise if we attach it here
2924 -- we will finalize the returned result prematurely).
2927 Make_Object_Declaration (Loc,
2928 Defining_Identifier => Copy_Ent,
2929 Object_Definition => New_Occurrence_Of (Return_Type, Loc),
2930 Expression => Relocate_Node (Exp));
2932 Set_Assignment_OK (Decl);
2933 Set_Delay_Finalize_Attach (Decl);
2934 Insert_Action (N, Decl);
2936 -- Now the actual return uses the copied value
2938 Rewrite (Exp, New_Occurrence_Of (Copy_Ent, Loc));
2939 Analyze_And_Resolve (Exp, Return_Type);
2941 -- Since we have made the copy, gigi does not have to, so
2942 -- we set the By_Ref flag to prevent another copy being made.
2946 -- Non-controlled cases
2949 Test_Copy_Required (Exp);
2951 -- If a local copy is required, then gigi will make the
2952 -- copy, otherwise, we can return the result directly,
2953 -- so set By_Ref to suppress the gigi copy.
2955 if not Local_Copy_Required then
2959 end No_Secondary_Stack_Case;
2961 -- Here if secondary stack is used
2964 -- Make sure that no surrounding block will reclaim the
2965 -- secondary-stack on which we are going to put the result.
2966 -- Not only may this introduce secondary stack leaks but worse,
2967 -- if the reclamation is done too early, then the result we are
2968 -- returning may get clobbered. See example in 7417-003.
2971 S : Entity_Id := Current_Scope;
2974 while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop
2975 Set_Sec_Stack_Needed_For_Return (S, True);
2976 S := Enclosing_Dynamic_Scope (S);
2980 -- Optimize the case where the result is a function call. In this
2981 -- case either the result is already on the secondary stack, or is
2982 -- already being returned with the stack pointer depressed and no
2983 -- further processing is required except to set the By_Ref flag to
2984 -- ensure that gigi does not attempt an extra unnecessary copy.
2985 -- (actually not just unnecessary but harmfully wrong in the case
2986 -- of a controlled type, where gigi does not know how to do a copy).
2987 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2988 -- the copy for array types if the constrained status of the
2989 -- target type is different from that of the expression.
2991 if Requires_Transient_Scope (T)
2993 (not Is_Array_Type (T)
2994 or else Is_Constrained (T) = Is_Constrained (Return_Type)
2995 or else Controlled_Type (T))
2996 and then Nkind (Exp) = N_Function_Call
3000 -- For controlled types, do the allocation on the sec-stack
3001 -- manually in order to call adjust at the right time
3002 -- type Anon1 is access Return_Type;
3003 -- for Anon1'Storage_pool use ss_pool;
3004 -- Anon2 : anon1 := new Return_Type'(expr);
3005 -- return Anon2.all;
3007 elsif Controlled_Type (Utyp) then
3009 Loc : constant Source_Ptr := Sloc (N);
3010 Temp : constant Entity_Id :=
3011 Make_Defining_Identifier (Loc,
3012 Chars => New_Internal_Name ('R'));
3013 Acc_Typ : constant Entity_Id :=
3014 Make_Defining_Identifier (Loc,
3015 Chars => New_Internal_Name ('A'));
3016 Alloc_Node : Node_Id;
3019 Set_Ekind (Acc_Typ, E_Access_Type);
3021 Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool));
3024 Make_Allocator (Loc,
3026 Make_Qualified_Expression (Loc,
3027 Subtype_Mark => New_Reference_To (Etype (Exp), Loc),
3028 Expression => Relocate_Node (Exp)));
3030 Insert_List_Before_And_Analyze (N, New_List (
3031 Make_Full_Type_Declaration (Loc,
3032 Defining_Identifier => Acc_Typ,
3034 Make_Access_To_Object_Definition (Loc,
3035 Subtype_Indication =>
3036 New_Reference_To (Return_Type, Loc))),
3038 Make_Object_Declaration (Loc,
3039 Defining_Identifier => Temp,
3040 Object_Definition => New_Reference_To (Acc_Typ, Loc),
3041 Expression => Alloc_Node)));
3044 Make_Explicit_Dereference (Loc,
3045 Prefix => New_Reference_To (Temp, Loc)));
3047 Analyze_And_Resolve (Exp, Return_Type);
3050 -- Otherwise use the gigi mechanism to allocate result on the
3054 Set_Storage_Pool (N, RTE (RE_SS_Pool));
3056 -- If we are generating code for the Java VM do not use
3057 -- SS_Allocate since everything is heap-allocated anyway.
3060 Set_Procedure_To_Call (N, RTE (RE_SS_Allocate));
3066 when RE_Not_Available =>
3068 end Expand_N_Return_Statement;
3070 ------------------------------
3071 -- Make_Tag_Ctrl_Assignment --
3072 ------------------------------
3074 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is
3075 Loc : constant Source_Ptr := Sloc (N);
3076 L : constant Node_Id := Name (N);
3077 T : constant Entity_Id := Underlying_Type (Etype (L));
3079 Ctrl_Act : constant Boolean := Controlled_Type (T)
3080 and then not No_Ctrl_Actions (N);
3082 Save_Tag : constant Boolean := Is_Tagged_Type (T)
3083 and then not No_Ctrl_Actions (N)
3084 and then not Java_VM;
3085 -- Tags are not saved and restored when Java_VM because JVM tags
3086 -- are represented implicitly in objects.
3089 Tag_Tmp : Entity_Id;
3094 -- Finalize the target of the assignment when controlled.
3095 -- We have two exceptions here:
3097 -- 1. If we are in an init proc since it is an initialization
3098 -- more than an assignment
3100 -- 2. If the left-hand side is a temporary that was not initialized
3101 -- (or the parent part of a temporary since it is the case in
3102 -- extension aggregates). Such a temporary does not come from
3103 -- source. We must examine the original node for the prefix, because
3104 -- it may be a component of an entry formal, in which case it has
3105 -- been rewritten and does not appear to come from source either.
3107 -- Case of init proc
3109 if not Ctrl_Act then
3112 -- The left hand side is an uninitialized temporary
3114 elsif Nkind (L) = N_Type_Conversion
3115 and then Is_Entity_Name (Expression (L))
3116 and then No_Initialization (Parent (Entity (Expression (L))))
3120 Append_List_To (Res,
3122 Ref => Duplicate_Subexpr_No_Checks (L),
3124 With_Detach => New_Reference_To (Standard_False, Loc)));
3127 -- Save the Tag in a local variable Tag_Tmp
3131 Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
3134 Make_Object_Declaration (Loc,
3135 Defining_Identifier => Tag_Tmp,
3136 Object_Definition => New_Reference_To (RTE (RE_Tag), Loc),
3138 Make_Selected_Component (Loc,
3139 Prefix => Duplicate_Subexpr_No_Checks (L),
3140 Selector_Name => New_Reference_To (Tag_Component (T), Loc))));
3142 -- Otherwise Tag_Tmp not used
3148 -- Processing for controlled types and types with controlled components
3150 -- Variables of such types contain pointers used to chain them in
3151 -- finalization lists, in addition to user data. These pointers are
3152 -- specific to each object of the type, not to the value being assigned.
3153 -- Thus they need to be left intact during the assignment. We achieve
3154 -- this by constructing a Storage_Array subtype, and by overlaying
3155 -- objects of this type on the source and target of the assignment.
3156 -- The assignment is then rewritten to assignments of slices of these
3157 -- arrays, copying the user data, and leaving the pointers untouched.
3160 Controlled_Actions : declare
3162 -- A reference to the Prev component of the record controller
3164 First_After_Root : Node_Id := Empty;
3165 -- Index of first byte to be copied (used to skip
3166 -- Root_Controlled in controlled objects).
3168 Last_Before_Hole : Node_Id := Empty;
3169 -- Index of last byte to be copied before outermost record
3172 Hole_Length : Node_Id := Empty;
3173 -- Length of record controller data (Prev and Next pointers)
3175 First_After_Hole : Node_Id := Empty;
3176 -- Index of first byte to be copied after outermost record
3179 Expr, Source_Size : Node_Id;
3180 -- Used for computation of the size of the data to be copied
3182 Range_Type : Entity_Id;
3183 Opaque_Type : Entity_Id;
3185 function Build_Slice
3188 Hi : Node_Id) return Node_Id;
3189 -- Build and return a slice of an array of type S overlaid
3190 -- on object Rec, with bounds specified by Lo and Hi. If either
3191 -- bound is empty, a default of S'First (respectively S'Last)
3198 function Build_Slice
3201 Hi : Node_Id) return Node_Id
3206 Opaque : constant Node_Id :=
3207 Unchecked_Convert_To (Opaque_Type,
3208 Make_Attribute_Reference (Loc,
3210 Attribute_Name => Name_Address));
3211 -- Access value designating an opaque storage array of
3212 -- type S overlaid on record Rec.
3215 -- Compute slice bounds using S'First (1) and S'Last
3216 -- as default values when not specified by the caller.
3219 Lo_Bound := Make_Integer_Literal (Loc, 1);
3225 Hi_Bound := Make_Attribute_Reference (Loc,
3226 Prefix => New_Occurrence_Of (Range_Type, Loc),
3227 Attribute_Name => Name_Last);
3232 return Make_Slice (Loc,
3235 Discrete_Range => Make_Range (Loc,
3236 Lo_Bound, Hi_Bound));
3239 -- Start of processing for Controlled_Actions
3242 -- Create a constrained subtype of Storage_Array whose size
3243 -- corresponds to the value being assigned.
3245 -- subtype G is Storage_Offset range
3246 -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit
3248 Expr := Duplicate_Subexpr_No_Checks (Expression (N));
3250 if Nkind (Expr) = N_Qualified_Expression then
3251 Expr := Expression (Expr);
3257 Make_Attribute_Reference (Loc,
3263 Make_Integer_Literal (Loc,
3264 System_Storage_Unit - 1));
3266 -- If Expr is a type conversion, standard Ada does not allow
3267 -- 'Size to be taken on it, but Gigi can handle this case,
3268 -- and thus we can determine the amount of data to be copied.
3269 -- The appropriate circuitry is enabled only for conversions
3270 -- that do not Come_From_Source.
3272 Set_Comes_From_Source (Prefix (Left_Opnd (Source_Size)), False);
3275 Make_Op_Divide (Loc,
3276 Left_Opnd => Source_Size,
3278 Make_Integer_Literal (Loc,
3279 Intval => System_Storage_Unit));
3282 Make_Defining_Identifier (Loc,
3283 New_Internal_Name ('G'));
3286 Make_Subtype_Declaration (Loc,
3287 Defining_Identifier => Range_Type,
3288 Subtype_Indication =>
3289 Make_Subtype_Indication (Loc,
3291 New_Reference_To (RTE (RE_Storage_Offset), Loc),
3292 Constraint => Make_Range_Constraint (Loc,
3295 Low_Bound => Make_Integer_Literal (Loc, 1),
3296 High_Bound => Source_Size)))));
3298 -- subtype S is Storage_Array (G)
3301 Make_Subtype_Declaration (Loc,
3302 Defining_Identifier =>
3303 Make_Defining_Identifier (Loc,
3304 New_Internal_Name ('S')),
3305 Subtype_Indication =>
3306 Make_Subtype_Indication (Loc,
3308 New_Reference_To (RTE (RE_Storage_Array), Loc),
3310 Make_Index_Or_Discriminant_Constraint (Loc,
3312 New_List (New_Reference_To (Range_Type, Loc))))));
3314 -- type A is access S
3317 Make_Defining_Identifier (Loc,
3318 Chars => New_Internal_Name ('A'));
3321 Make_Full_Type_Declaration (Loc,
3322 Defining_Identifier => Opaque_Type,
3324 Make_Access_To_Object_Definition (Loc,
3325 Subtype_Indication =>
3327 Defining_Identifier (Last (Res)), Loc))));
3329 -- Generate appropriate slice assignments
3331 First_After_Root := Make_Integer_Literal (Loc, 1);
3333 -- For the case of a controlled object, skip the
3334 -- Root_Controlled part.
3336 if Is_Controlled (T) then
3340 Make_Op_Divide (Loc,
3341 Make_Attribute_Reference (Loc,
3343 New_Occurrence_Of (RTE (RE_Root_Controlled), Loc),
3344 Attribute_Name => Name_Size),
3345 Make_Integer_Literal (Loc, System_Storage_Unit)));
3348 -- For the case of a record with controlled components, skip
3349 -- the Prev and Next components of the record controller.
3350 -- These components constitute a 'hole' in the middle of the
3351 -- data to be copied.
3353 if Has_Controlled_Component (T) then
3355 Make_Selected_Component (Loc,
3357 Make_Selected_Component (Loc,
3358 Prefix => Duplicate_Subexpr_No_Checks (L),
3360 New_Reference_To (Controller_Component (T), Loc)),
3361 Selector_Name => Make_Identifier (Loc, Name_Prev));
3363 -- Last index before hole: determined by position of
3364 -- the _Controller.Prev component.
3367 Make_Defining_Identifier (Loc,
3368 New_Internal_Name ('L'));
3371 Make_Object_Declaration (Loc,
3372 Defining_Identifier => Last_Before_Hole,
3373 Object_Definition => New_Occurrence_Of (
3374 RTE (RE_Storage_Offset), Loc),
3375 Constant_Present => True,
3376 Expression => Make_Op_Add (Loc,
3377 Make_Attribute_Reference (Loc,
3379 Attribute_Name => Name_Position),
3380 Make_Attribute_Reference (Loc,
3381 Prefix => New_Copy_Tree (Prefix (Prev_Ref)),
3382 Attribute_Name => Name_Position))));
3384 -- Hole length: size of the Prev and Next components
3387 Make_Op_Multiply (Loc,
3388 Left_Opnd => Make_Integer_Literal (Loc, Uint_2),
3390 Make_Op_Divide (Loc,
3392 Make_Attribute_Reference (Loc,
3393 Prefix => New_Copy_Tree (Prev_Ref),
3394 Attribute_Name => Name_Size),
3396 Make_Integer_Literal (Loc,
3397 Intval => System_Storage_Unit)));
3399 -- First index after hole
3402 Make_Defining_Identifier (Loc,
3403 New_Internal_Name ('F'));
3406 Make_Object_Declaration (Loc,
3407 Defining_Identifier => First_After_Hole,
3408 Object_Definition => New_Occurrence_Of (
3409 RTE (RE_Storage_Offset), Loc),
3410 Constant_Present => True,
3416 New_Occurrence_Of (Last_Before_Hole, Loc),
3417 Right_Opnd => Hole_Length),
3418 Right_Opnd => Make_Integer_Literal (Loc, 1))));
3420 Last_Before_Hole := New_Occurrence_Of (Last_Before_Hole, Loc);
3421 First_After_Hole := New_Occurrence_Of (First_After_Hole, Loc);
3424 -- Assign the first slice (possibly skipping Root_Controlled,
3425 -- up to the beginning of the record controller if present,
3426 -- up to the end of the object if not).
3428 Append_To (Res, Make_Assignment_Statement (Loc,
3429 Name => Build_Slice (
3430 Rec => Duplicate_Subexpr_No_Checks (L),
3431 Lo => First_After_Root,
3432 Hi => Last_Before_Hole),
3434 Expression => Build_Slice (
3435 Rec => Expression (N),
3436 Lo => First_After_Root,
3437 Hi => New_Copy_Tree (Last_Before_Hole))));
3439 if Present (First_After_Hole) then
3441 -- If a record controller is present, copy the second slice,
3442 -- from right after the _Controller.Next component up to the
3443 -- end of the object.
3445 Append_To (Res, Make_Assignment_Statement (Loc,
3446 Name => Build_Slice (
3447 Rec => Duplicate_Subexpr_No_Checks (L),
3448 Lo => First_After_Hole,
3450 Expression => Build_Slice (
3451 Rec => Duplicate_Subexpr_No_Checks (Expression (N)),
3452 Lo => New_Copy_Tree (First_After_Hole),
3455 end Controlled_Actions;
3458 Append_To (Res, Relocate_Node (N));
3465 Make_Assignment_Statement (Loc,
3467 Make_Selected_Component (Loc,
3468 Prefix => Duplicate_Subexpr_No_Checks (L),
3469 Selector_Name => New_Reference_To (Tag_Component (T), Loc)),
3470 Expression => New_Reference_To (Tag_Tmp, Loc)));
3473 -- Adjust the target after the assignment when controlled (not in the
3474 -- init proc since it is an initialization more than an assignment).
3477 Append_List_To (Res,
3479 Ref => Duplicate_Subexpr_Move_Checks (L),
3481 Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc),
3482 With_Attach => Make_Integer_Literal (Loc, 0)));
3488 -- Could use comment here ???
3490 when RE_Not_Available =>
3492 end Make_Tag_Ctrl_Assignment;
3494 ------------------------------------
3495 -- Possible_Bit_Aligned_Component --
3496 ------------------------------------
3498 function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean is
3502 -- Case of indexed component
3504 when N_Indexed_Component =>
3506 P : constant Node_Id := Prefix (N);
3507 Ptyp : constant Entity_Id := Etype (P);
3510 -- If we know the component size and it is less than 64, then
3511 -- we are definitely OK. The back end always does assignment
3512 -- of misaligned small objects correctly.
3514 if Known_Static_Component_Size (Ptyp)
3515 and then Component_Size (Ptyp) <= 64
3519 -- Otherwise, we need to test the prefix, to see if we are
3520 -- indexing from a possibly unaligned component.
3523 return Possible_Bit_Aligned_Component (P);
3527 -- Case of selected component
3529 when N_Selected_Component =>
3531 P : constant Node_Id := Prefix (N);
3532 Comp : constant Entity_Id := Entity (Selector_Name (N));
3535 -- If there is no component clause, then we are in the clear
3536 -- since the back end will never misalign a large component
3537 -- unless it is forced to do so. In the clear means we need
3538 -- only the recursive test on the prefix.
3540 if Component_May_Be_Bit_Aligned (Comp) then
3543 return Possible_Bit_Aligned_Component (P);
3547 -- If we have neither a record nor array component, it means that
3548 -- we have fallen off the top testing prefixes recursively, and
3549 -- we now have a stand alone object, where we don't have a problem
3555 end Possible_Bit_Aligned_Component;