1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2005, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 with Atree; use Atree;
28 with Checks; use Checks;
29 with Einfo; use Einfo;
30 with Elists; use Elists;
31 with Exp_Aggr; use Exp_Aggr;
32 with Exp_Ch7; use Exp_Ch7;
33 with Exp_Ch11; use Exp_Ch11;
34 with Exp_Dbug; use Exp_Dbug;
35 with Exp_Pakd; use Exp_Pakd;
36 with Exp_Tss; use Exp_Tss;
37 with Exp_Util; use Exp_Util;
38 with Hostparm; use Hostparm;
39 with Nlists; use Nlists;
40 with Nmake; use Nmake;
42 with Restrict; use Restrict;
43 with Rident; use Rident;
44 with Rtsfind; use Rtsfind;
45 with Sinfo; use Sinfo;
47 with Sem_Ch3; use Sem_Ch3;
48 with Sem_Ch5; use Sem_Ch5;
49 with Sem_Ch8; use Sem_Ch8;
50 with Sem_Ch13; use Sem_Ch13;
51 with Sem_Eval; use Sem_Eval;
52 with Sem_Res; use Sem_Res;
53 with Sem_Util; use Sem_Util;
54 with Snames; use Snames;
55 with Stand; use Stand;
56 with Stringt; use Stringt;
57 with Tbuild; use Tbuild;
58 with Ttypes; use Ttypes;
59 with Uintp; use Uintp;
60 with Validsw; use Validsw;
62 package body Exp_Ch5 is
64 function Change_Of_Representation (N : Node_Id) return Boolean;
65 -- Determine if the right hand side of the assignment N is a type
66 -- conversion which requires a change of representation. Called
67 -- only for the array and record cases.
69 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id);
70 -- N is an assignment which assigns an array value. This routine process
71 -- the various special cases and checks required for such assignments,
72 -- including change of representation. Rhs is normally simply the right
73 -- hand side of the assignment, except that if the right hand side is
74 -- a type conversion or a qualified expression, then the Rhs is the
75 -- actual expression inside any such type conversions or qualifications.
77 function Expand_Assign_Array_Loop
84 Rev : Boolean) return Node_Id;
85 -- N is an assignment statement which assigns an array value. This routine
86 -- expands the assignment into a loop (or nested loops for the case of a
87 -- multi-dimensional array) to do the assignment component by component.
88 -- Larray and Rarray are the entities of the actual arrays on the left
89 -- hand and right hand sides. L_Type and R_Type are the types of these
90 -- arrays (which may not be the same, due to either sliding, or to a
91 -- change of representation case). Ndim is the number of dimensions and
92 -- the parameter Rev indicates if the loops run normally (Rev = False),
93 -- or reversed (Rev = True). The value returned is the constructed
94 -- loop statement. Auxiliary declarations are inserted before node N
95 -- using the standard Insert_Actions mechanism.
97 procedure Expand_Assign_Record (N : Node_Id);
98 -- N is an assignment of a non-tagged record value. This routine handles
99 -- the case where the assignment must be made component by component,
100 -- either because the target is not byte aligned, or there is a change
101 -- of representation.
103 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
104 -- Generate the necessary code for controlled and tagged assignment,
105 -- that is to say, finalization of the target before, adjustement of
106 -- the target after and save and restore of the tag and finalization
107 -- pointers which are not 'part of the value' and must not be changed
108 -- upon assignment. N is the original Assignment node.
110 function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean;
111 -- This function is used in processing the assignment of a record or
112 -- indexed component. The argument N is either the left hand or right
113 -- hand side of an assignment, and this function determines if there
114 -- is a record component reference where the record may be bit aligned
115 -- in a manner that causes trouble for the back end (see description
116 -- of Exp_Util.Component_May_Be_Bit_Aligned for further details).
118 ------------------------------
119 -- Change_Of_Representation --
120 ------------------------------
122 function Change_Of_Representation (N : Node_Id) return Boolean is
123 Rhs : constant Node_Id := Expression (N);
126 Nkind (Rhs) = N_Type_Conversion
128 not Same_Representation (Etype (Rhs), Etype (Expression (Rhs)));
129 end Change_Of_Representation;
131 -------------------------
132 -- Expand_Assign_Array --
133 -------------------------
135 -- There are two issues here. First, do we let Gigi do a block move, or
136 -- do we expand out into a loop? Second, we need to set the two flags
137 -- Forwards_OK and Backwards_OK which show whether the block move (or
138 -- corresponding loops) can be legitimately done in a forwards (low to
139 -- high) or backwards (high to low) manner.
141 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is
142 Loc : constant Source_Ptr := Sloc (N);
144 Lhs : constant Node_Id := Name (N);
146 Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs);
147 Act_Rhs : Node_Id := Get_Referenced_Object (Rhs);
149 L_Type : constant Entity_Id :=
150 Underlying_Type (Get_Actual_Subtype (Act_Lhs));
151 R_Type : Entity_Id :=
152 Underlying_Type (Get_Actual_Subtype (Act_Rhs));
154 L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice;
155 R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice;
157 Crep : constant Boolean := Change_Of_Representation (N);
162 Ndim : constant Pos := Number_Dimensions (L_Type);
164 Loop_Required : Boolean := False;
165 -- This switch is set to True if the array move must be done using
166 -- an explicit front end generated loop.
168 procedure Apply_Dereference (Arg : in out Node_Id);
169 -- If the argument is an access to an array, and the assignment is
170 -- converted into a procedure call, apply explicit dereference.
172 function Has_Address_Clause (Exp : Node_Id) return Boolean;
173 -- Test if Exp is a reference to an array whose declaration has
174 -- an address clause, or it is a slice of such an array.
176 function Is_Formal_Array (Exp : Node_Id) return Boolean;
177 -- Test if Exp is a reference to an array which is either a formal
178 -- parameter or a slice of a formal parameter. These are the cases
179 -- where hidden aliasing can occur.
181 function Is_Non_Local_Array (Exp : Node_Id) return Boolean;
182 -- Determine if Exp is a reference to an array variable which is other
183 -- than an object defined in the current scope, or a slice of such
184 -- an object. Such objects can be aliased to parameters (unlike local
185 -- array references).
187 -----------------------
188 -- Apply_Dereference --
189 -----------------------
191 procedure Apply_Dereference (Arg : in out Node_Id) is
192 Typ : constant Entity_Id := Etype (Arg);
194 if Is_Access_Type (Typ) then
195 Rewrite (Arg, Make_Explicit_Dereference (Loc,
196 Prefix => Relocate_Node (Arg)));
197 Analyze_And_Resolve (Arg, Designated_Type (Typ));
199 end Apply_Dereference;
201 ------------------------
202 -- Has_Address_Clause --
203 ------------------------
205 function Has_Address_Clause (Exp : Node_Id) return Boolean is
208 (Is_Entity_Name (Exp) and then
209 Present (Address_Clause (Entity (Exp))))
211 (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp)));
212 end Has_Address_Clause;
214 ---------------------
215 -- Is_Formal_Array --
216 ---------------------
218 function Is_Formal_Array (Exp : Node_Id) return Boolean is
221 (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp)))
223 (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp)));
226 ------------------------
227 -- Is_Non_Local_Array --
228 ------------------------
230 function Is_Non_Local_Array (Exp : Node_Id) return Boolean is
232 return (Is_Entity_Name (Exp)
233 and then Scope (Entity (Exp)) /= Current_Scope)
234 or else (Nkind (Exp) = N_Slice
235 and then Is_Non_Local_Array (Prefix (Exp)));
236 end Is_Non_Local_Array;
238 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
240 Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs);
241 Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs);
243 Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs);
244 Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs);
246 -- Start of processing for Expand_Assign_Array
249 -- Deal with length check, note that the length check is done with
250 -- respect to the right hand side as given, not a possible underlying
251 -- renamed object, since this would generate incorrect extra checks.
253 Apply_Length_Check (Rhs, L_Type);
255 -- We start by assuming that the move can be done in either
256 -- direction, i.e. that the two sides are completely disjoint.
258 Set_Forwards_OK (N, True);
259 Set_Backwards_OK (N, True);
261 -- Normally it is only the slice case that can lead to overlap,
262 -- and explicit checks for slices are made below. But there is
263 -- one case where the slice can be implicit and invisible to us
264 -- and that is the case where we have a one dimensional array,
265 -- and either both operands are parameters, or one is a parameter
266 -- and the other is a global variable. In this case the parameter
267 -- could be a slice that overlaps with the other parameter.
269 -- Check for the case of slices requiring an explicit loop. Normally
270 -- it is only the explicit slice cases that bother us, but in the
271 -- case of one dimensional arrays, parameters can be slices that
272 -- are passed by reference, so we can have aliasing for assignments
273 -- from one parameter to another, or assignments between parameters
274 -- and nonlocal variables. However, if the array subtype is a
275 -- constrained first subtype in the parameter case, then we don't
276 -- have to worry about overlap, since slice assignments aren't
277 -- possible (other than for a slice denoting the whole array).
279 -- Note: overlap is never possible if there is a change of
280 -- representation, so we can exclude this case.
285 ((Lhs_Formal and Rhs_Formal)
287 (Lhs_Formal and Rhs_Non_Local_Var)
289 (Rhs_Formal and Lhs_Non_Local_Var))
291 (not Is_Constrained (Etype (Lhs))
292 or else not Is_First_Subtype (Etype (Lhs)))
294 -- In the case of compiling for the Java Virtual Machine,
295 -- slices are always passed by making a copy, so we don't
296 -- have to worry about overlap. We also want to prevent
297 -- generation of "<" comparisons for array addresses,
298 -- since that's a meaningless operation on the JVM.
302 Set_Forwards_OK (N, False);
303 Set_Backwards_OK (N, False);
305 -- Note: the bit-packed case is not worrisome here, since if
306 -- we have a slice passed as a parameter, it is always aligned
307 -- on a byte boundary, and if there are no explicit slices, the
308 -- assignment can be performed directly.
311 -- We certainly must use a loop for change of representation
312 -- and also we use the operand of the conversion on the right
313 -- hand side as the effective right hand side (the component
314 -- types must match in this situation).
317 Act_Rhs := Get_Referenced_Object (Rhs);
318 R_Type := Get_Actual_Subtype (Act_Rhs);
319 Loop_Required := True;
321 -- We require a loop if the left side is possibly bit unaligned
323 elsif Possible_Bit_Aligned_Component (Lhs)
325 Possible_Bit_Aligned_Component (Rhs)
327 Loop_Required := True;
329 -- Arrays with controlled components are expanded into a loop
330 -- to force calls to adjust at the component level.
332 elsif Has_Controlled_Component (L_Type) then
333 Loop_Required := True;
335 -- If object is atomic, we cannot tolerate a loop
337 elsif Is_Atomic_Object (Act_Lhs)
339 Is_Atomic_Object (Act_Rhs)
343 -- Loop is required if we have atomic components since we have to
344 -- be sure to do any accesses on an element by element basis.
346 elsif Has_Atomic_Components (L_Type)
347 or else Has_Atomic_Components (R_Type)
348 or else Is_Atomic (Component_Type (L_Type))
349 or else Is_Atomic (Component_Type (R_Type))
351 Loop_Required := True;
353 -- Case where no slice is involved
355 elsif not L_Slice and not R_Slice then
357 -- The following code deals with the case of unconstrained bit
358 -- packed arrays. The problem is that the template for such
359 -- arrays contains the bounds of the actual source level array,
361 -- But the copy of an entire array requires the bounds of the
362 -- underlying array. It would be nice if the back end could take
363 -- care of this, but right now it does not know how, so if we
364 -- have such a type, then we expand out into a loop, which is
365 -- inefficient but works correctly. If we don't do this, we
366 -- get the wrong length computed for the array to be moved.
367 -- The two cases we need to worry about are:
369 -- Explicit deference of an unconstrained packed array type as
370 -- in the following example:
373 -- type BITS is array(INTEGER range <>) of BOOLEAN;
374 -- pragma PACK(BITS);
375 -- type A is access BITS;
378 -- P1 := new BITS (1 .. 65_535);
379 -- P2 := new BITS (1 .. 65_535);
383 -- A formal parameter reference with an unconstrained bit
384 -- array type is the other case we need to worry about (here
385 -- we assume the same BITS type declared above:
387 -- procedure Write_All (File : out BITS; Contents : in BITS);
389 -- File.Storage := Contents;
392 -- We expand to a loop in either of these two cases
394 -- Question for future thought. Another potentially more efficient
395 -- approach would be to create the actual subtype, and then do an
396 -- unchecked conversion to this actual subtype ???
398 Check_Unconstrained_Bit_Packed_Array : declare
400 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean;
401 -- Function to perform required test for the first case,
402 -- above (dereference of an unconstrained bit packed array)
404 -----------------------
405 -- Is_UBPA_Reference --
406 -----------------------
408 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is
409 Typ : constant Entity_Id := Underlying_Type (Etype (Opnd));
411 Des_Type : Entity_Id;
414 if Present (Packed_Array_Type (Typ))
415 and then Is_Array_Type (Packed_Array_Type (Typ))
416 and then not Is_Constrained (Packed_Array_Type (Typ))
420 elsif Nkind (Opnd) = N_Explicit_Dereference then
421 P_Type := Underlying_Type (Etype (Prefix (Opnd)));
423 if not Is_Access_Type (P_Type) then
427 Des_Type := Designated_Type (P_Type);
429 Is_Bit_Packed_Array (Des_Type)
430 and then not Is_Constrained (Des_Type);
436 end Is_UBPA_Reference;
438 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
441 if Is_UBPA_Reference (Lhs)
443 Is_UBPA_Reference (Rhs)
445 Loop_Required := True;
447 -- Here if we do not have the case of a reference to a bit
448 -- packed unconstrained array case. In this case gigi can
449 -- most certainly handle the assignment if a forwards move
452 -- (could it handle the backwards case also???)
454 elsif Forwards_OK (N) then
457 end Check_Unconstrained_Bit_Packed_Array;
459 -- The back end can always handle the assignment if the right side is a
460 -- string literal (note that overlap is definitely impossible in this
461 -- case). If the type is packed, a string literal is always converted
462 -- into aggregate, except in the case of a null slice, for which no
463 -- aggregate can be written. In that case, rewrite the assignment as a
464 -- null statement, a length check has already been emitted to verify
465 -- that the range of the left-hand side is empty.
467 -- Note that this code is not executed if we had an assignment of
468 -- a string literal to a non-bit aligned component of a record, a
469 -- case which cannot be handled by the backend
471 elsif Nkind (Rhs) = N_String_Literal then
472 if String_Length (Strval (Rhs)) = 0
473 and then Is_Bit_Packed_Array (L_Type)
475 Rewrite (N, Make_Null_Statement (Loc));
481 -- If either operand is bit packed, then we need a loop, since we
482 -- can't be sure that the slice is byte aligned. Similarly, if either
483 -- operand is a possibly unaligned slice, then we need a loop (since
484 -- the back end cannot handle unaligned slices).
486 elsif Is_Bit_Packed_Array (L_Type)
487 or else Is_Bit_Packed_Array (R_Type)
488 or else Is_Possibly_Unaligned_Slice (Lhs)
489 or else Is_Possibly_Unaligned_Slice (Rhs)
491 Loop_Required := True;
493 -- If we are not bit-packed, and we have only one slice, then no
494 -- overlap is possible except in the parameter case, so we can let
495 -- the back end handle things.
497 elsif not (L_Slice and R_Slice) then
498 if Forwards_OK (N) then
503 -- If the right-hand side is a string literal, introduce a temporary
504 -- for it, for use in the generated loop that will follow.
506 if Nkind (Rhs) = N_String_Literal then
508 Temp : constant Entity_Id :=
509 Make_Defining_Identifier (Loc, Name_T);
514 Make_Object_Declaration (Loc,
515 Defining_Identifier => Temp,
516 Object_Definition => New_Occurrence_Of (L_Type, Loc),
517 Expression => Relocate_Node (Rhs));
519 Insert_Action (N, Decl);
520 Rewrite (Rhs, New_Occurrence_Of (Temp, Loc));
521 R_Type := Etype (Temp);
525 -- Come here to complete the analysis
527 -- Loop_Required: Set to True if we know that a loop is required
528 -- regardless of overlap considerations.
530 -- Forwards_OK: Set to False if we already know that a forwards
531 -- move is not safe, else set to True.
533 -- Backwards_OK: Set to False if we already know that a backwards
534 -- move is not safe, else set to True
536 -- Our task at this stage is to complete the overlap analysis, which
537 -- can result in possibly setting Forwards_OK or Backwards_OK to
538 -- False, and then generating the final code, either by deciding
539 -- that it is OK after all to let Gigi handle it, or by generating
540 -- appropriate code in the front end.
543 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
544 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type));
546 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ);
547 Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ);
548 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ);
549 Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ);
551 Act_L_Array : Node_Id;
552 Act_R_Array : Node_Id;
558 Cresult : Compare_Result;
561 -- Get the expressions for the arrays. If we are dealing with a
562 -- private type, then convert to the underlying type. We can do
563 -- direct assignments to an array that is a private type, but
564 -- we cannot assign to elements of the array without this extra
565 -- unchecked conversion.
567 if Nkind (Act_Lhs) = N_Slice then
568 Larray := Prefix (Act_Lhs);
572 if Is_Private_Type (Etype (Larray)) then
575 (Underlying_Type (Etype (Larray)), Larray);
579 if Nkind (Act_Rhs) = N_Slice then
580 Rarray := Prefix (Act_Rhs);
584 if Is_Private_Type (Etype (Rarray)) then
587 (Underlying_Type (Etype (Rarray)), Rarray);
591 -- If both sides are slices, we must figure out whether
592 -- it is safe to do the move in one direction or the other
593 -- It is always safe if there is a change of representation
594 -- since obviously two arrays with different representations
595 -- cannot possibly overlap.
597 if (not Crep) and L_Slice and R_Slice then
598 Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
599 Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
601 -- If both left and right hand arrays are entity names, and
602 -- refer to different entities, then we know that the move
603 -- is safe (the two storage areas are completely disjoint).
605 if Is_Entity_Name (Act_L_Array)
606 and then Is_Entity_Name (Act_R_Array)
607 and then Entity (Act_L_Array) /= Entity (Act_R_Array)
611 -- Otherwise, we assume the worst, which is that the two
612 -- arrays are the same array. There is no need to check if
613 -- we know that is the case, because if we don't know it,
614 -- we still have to assume it!
616 -- Generally if the same array is involved, then we have
617 -- an overlapping case. We will have to really assume the
618 -- worst (i.e. set neither of the OK flags) unless we can
619 -- determine the lower or upper bounds at compile time and
623 Cresult := Compile_Time_Compare (Left_Lo, Right_Lo);
625 if Cresult = Unknown then
626 Cresult := Compile_Time_Compare (Left_Hi, Right_Hi);
630 when LT | LE | EQ => Set_Backwards_OK (N, False);
631 when GT | GE => Set_Forwards_OK (N, False);
632 when NE | Unknown => Set_Backwards_OK (N, False);
633 Set_Forwards_OK (N, False);
638 -- If after that analysis, Forwards_OK is still True, and
639 -- Loop_Required is False, meaning that we have not discovered
640 -- some non-overlap reason for requiring a loop, then we can
641 -- still let gigi handle it.
643 if not Loop_Required then
644 if Forwards_OK (N) then
648 -- Here is where a memmove would be appropriate ???
652 -- At this stage we have to generate an explicit loop, and
653 -- we have the following cases:
655 -- Forwards_OK = True
657 -- Rnn : right_index := right_index'First;
658 -- for Lnn in left-index loop
659 -- left (Lnn) := right (Rnn);
660 -- Rnn := right_index'Succ (Rnn);
663 -- Note: the above code MUST be analyzed with checks off,
664 -- because otherwise the Succ could overflow. But in any
665 -- case this is more efficient!
667 -- Forwards_OK = False, Backwards_OK = True
669 -- Rnn : right_index := right_index'Last;
670 -- for Lnn in reverse left-index loop
671 -- left (Lnn) := right (Rnn);
672 -- Rnn := right_index'Pred (Rnn);
675 -- Note: the above code MUST be analyzed with checks off,
676 -- because otherwise the Pred could overflow. But in any
677 -- case this is more efficient!
679 -- Forwards_OK = Backwards_OK = False
681 -- This only happens if we have the same array on each side. It is
682 -- possible to create situations using overlays that violate this,
683 -- but we simply do not promise to get this "right" in this case.
685 -- There are two possible subcases. If the No_Implicit_Conditionals
686 -- restriction is set, then we generate the following code:
689 -- T : constant <operand-type> := rhs;
694 -- If implicit conditionals are permitted, then we generate:
696 -- if Left_Lo <= Right_Lo then
697 -- <code for Forwards_OK = True above>
699 -- <code for Backwards_OK = True above>
702 -- Cases where either Forwards_OK or Backwards_OK is true
704 if Forwards_OK (N) or else Backwards_OK (N) then
705 if Controlled_Type (Component_Type (L_Type))
706 and then Base_Type (L_Type) = Base_Type (R_Type)
708 and then not No_Ctrl_Actions (N)
711 Proc : constant Entity_Id :=
712 TSS (Base_Type (L_Type), TSS_Slice_Assign);
716 Apply_Dereference (Larray);
717 Apply_Dereference (Rarray);
718 Actuals := New_List (
719 Duplicate_Subexpr (Larray, Name_Req => True),
720 Duplicate_Subexpr (Rarray, Name_Req => True),
721 Duplicate_Subexpr (Left_Lo, Name_Req => True),
722 Duplicate_Subexpr (Left_Hi, Name_Req => True),
723 Duplicate_Subexpr (Right_Lo, Name_Req => True),
724 Duplicate_Subexpr (Right_Hi, Name_Req => True));
728 Boolean_Literals (not Forwards_OK (N)), Loc));
731 Make_Procedure_Call_Statement (Loc,
732 Name => New_Reference_To (Proc, Loc),
733 Parameter_Associations => Actuals));
738 Expand_Assign_Array_Loop
739 (N, Larray, Rarray, L_Type, R_Type, Ndim,
740 Rev => not Forwards_OK (N)));
743 -- Case of both are false with No_Implicit_Conditionals
745 elsif Restriction_Active (No_Implicit_Conditionals) then
747 T : constant Entity_Id :=
748 Make_Defining_Identifier (Loc, Chars => Name_T);
752 Make_Block_Statement (Loc,
753 Declarations => New_List (
754 Make_Object_Declaration (Loc,
755 Defining_Identifier => T,
756 Constant_Present => True,
758 New_Occurrence_Of (Etype (Rhs), Loc),
759 Expression => Relocate_Node (Rhs))),
761 Handled_Statement_Sequence =>
762 Make_Handled_Sequence_Of_Statements (Loc,
763 Statements => New_List (
764 Make_Assignment_Statement (Loc,
765 Name => Relocate_Node (Lhs),
766 Expression => New_Occurrence_Of (T, Loc))))));
769 -- Case of both are false with implicit conditionals allowed
772 -- Before we generate this code, we must ensure that the
773 -- left and right side array types are defined. They may
774 -- be itypes, and we cannot let them be defined inside the
775 -- if, since the first use in the then may not be executed.
777 Ensure_Defined (L_Type, N);
778 Ensure_Defined (R_Type, N);
780 -- We normally compare addresses to find out which way round
781 -- to do the loop, since this is realiable, and handles the
782 -- cases of parameters, conversions etc. But we can't do that
783 -- in the bit packed case or the Java VM case, because addresses
786 if not Is_Bit_Packed_Array (L_Type) and then not Java_VM then
790 Unchecked_Convert_To (RTE (RE_Integer_Address),
791 Make_Attribute_Reference (Loc,
793 Make_Indexed_Component (Loc,
795 Duplicate_Subexpr_Move_Checks (Larray, True),
796 Expressions => New_List (
797 Make_Attribute_Reference (Loc,
801 Attribute_Name => Name_First))),
802 Attribute_Name => Name_Address)),
805 Unchecked_Convert_To (RTE (RE_Integer_Address),
806 Make_Attribute_Reference (Loc,
808 Make_Indexed_Component (Loc,
810 Duplicate_Subexpr_Move_Checks (Rarray, True),
811 Expressions => New_List (
812 Make_Attribute_Reference (Loc,
816 Attribute_Name => Name_First))),
817 Attribute_Name => Name_Address)));
819 -- For the bit packed and Java VM cases we use the bounds.
820 -- That's OK, because we don't have to worry about parameters,
821 -- since they cannot cause overlap. Perhaps we should worry
822 -- about weird slice conversions ???
825 -- Copy the bounds and reset the Analyzed flag, because the
826 -- bounds of the index type itself may be universal, and must
827 -- must be reaanalyzed to acquire the proper type for Gigi.
829 Cleft_Lo := New_Copy_Tree (Left_Lo);
830 Cright_Lo := New_Copy_Tree (Right_Lo);
831 Set_Analyzed (Cleft_Lo, False);
832 Set_Analyzed (Cright_Lo, False);
836 Left_Opnd => Cleft_Lo,
837 Right_Opnd => Cright_Lo);
840 if Controlled_Type (Component_Type (L_Type))
841 and then Base_Type (L_Type) = Base_Type (R_Type)
843 and then not No_Ctrl_Actions (N)
846 -- Call TSS procedure for array assignment, passing the
847 -- the explicit bounds of right and left hand sides.
850 Proc : constant Node_Id :=
851 TSS (Base_Type (L_Type), TSS_Slice_Assign);
855 Apply_Dereference (Larray);
856 Apply_Dereference (Rarray);
857 Actuals := New_List (
858 Duplicate_Subexpr (Larray, Name_Req => True),
859 Duplicate_Subexpr (Rarray, Name_Req => True),
860 Duplicate_Subexpr (Left_Lo, Name_Req => True),
861 Duplicate_Subexpr (Left_Hi, Name_Req => True),
862 Duplicate_Subexpr (Right_Lo, Name_Req => True),
863 Duplicate_Subexpr (Right_Hi, Name_Req => True));
867 Right_Opnd => Condition));
870 Make_Procedure_Call_Statement (Loc,
871 Name => New_Reference_To (Proc, Loc),
872 Parameter_Associations => Actuals));
877 Make_Implicit_If_Statement (N,
878 Condition => Condition,
880 Then_Statements => New_List (
881 Expand_Assign_Array_Loop
882 (N, Larray, Rarray, L_Type, R_Type, Ndim,
885 Else_Statements => New_List (
886 Expand_Assign_Array_Loop
887 (N, Larray, Rarray, L_Type, R_Type, Ndim,
892 Analyze (N, Suppress => All_Checks);
896 when RE_Not_Available =>
898 end Expand_Assign_Array;
900 ------------------------------
901 -- Expand_Assign_Array_Loop --
902 ------------------------------
904 -- The following is an example of the loop generated for the case of
905 -- a two-dimensional array:
910 -- for L1b in 1 .. 100 loop
914 -- for L3b in 1 .. 100 loop
915 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
916 -- R4b := Tm1X2'succ(R4b);
919 -- R2b := Tm1X1'succ(R2b);
923 -- Here Rev is False, and Tm1Xn are the subscript types for the right
924 -- hand side. The declarations of R2b and R4b are inserted before the
925 -- original assignment statement.
927 function Expand_Assign_Array_Loop
934 Rev : Boolean) return Node_Id
936 Loc : constant Source_Ptr := Sloc (N);
938 Lnn : array (1 .. Ndim) of Entity_Id;
939 Rnn : array (1 .. Ndim) of Entity_Id;
940 -- Entities used as subscripts on left and right sides
942 L_Index_Type : array (1 .. Ndim) of Entity_Id;
943 R_Index_Type : array (1 .. Ndim) of Entity_Id;
944 -- Left and right index types
956 F_Or_L := Name_First;
960 -- Setup index types and subscript entities
967 L_Index := First_Index (L_Type);
968 R_Index := First_Index (R_Type);
970 for J in 1 .. Ndim loop
972 Make_Defining_Identifier (Loc,
973 Chars => New_Internal_Name ('L'));
976 Make_Defining_Identifier (Loc,
977 Chars => New_Internal_Name ('R'));
979 L_Index_Type (J) := Etype (L_Index);
980 R_Index_Type (J) := Etype (R_Index);
982 Next_Index (L_Index);
983 Next_Index (R_Index);
987 -- Now construct the assignment statement
990 ExprL : constant List_Id := New_List;
991 ExprR : constant List_Id := New_List;
994 for J in 1 .. Ndim loop
995 Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc));
996 Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc));
1000 Make_Assignment_Statement (Loc,
1002 Make_Indexed_Component (Loc,
1003 Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
1004 Expressions => ExprL),
1006 Make_Indexed_Component (Loc,
1007 Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
1008 Expressions => ExprR));
1010 -- We set assignment OK, since there are some cases, e.g. in object
1011 -- declarations, where we are actually assigning into a constant.
1012 -- If there really is an illegality, it was caught long before now,
1013 -- and was flagged when the original assignment was analyzed.
1015 Set_Assignment_OK (Name (Assign));
1017 -- Propagate the No_Ctrl_Actions flag to individual assignments
1019 Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
1022 -- Now construct the loop from the inside out, with the last subscript
1023 -- varying most rapidly. Note that Assign is first the raw assignment
1024 -- statement, and then subsequently the loop that wraps it up.
1026 for J in reverse 1 .. Ndim loop
1028 Make_Block_Statement (Loc,
1029 Declarations => New_List (
1030 Make_Object_Declaration (Loc,
1031 Defining_Identifier => Rnn (J),
1032 Object_Definition =>
1033 New_Occurrence_Of (R_Index_Type (J), Loc),
1035 Make_Attribute_Reference (Loc,
1036 Prefix => New_Occurrence_Of (R_Index_Type (J), Loc),
1037 Attribute_Name => F_Or_L))),
1039 Handled_Statement_Sequence =>
1040 Make_Handled_Sequence_Of_Statements (Loc,
1041 Statements => New_List (
1042 Make_Implicit_Loop_Statement (N,
1044 Make_Iteration_Scheme (Loc,
1045 Loop_Parameter_Specification =>
1046 Make_Loop_Parameter_Specification (Loc,
1047 Defining_Identifier => Lnn (J),
1048 Reverse_Present => Rev,
1049 Discrete_Subtype_Definition =>
1050 New_Reference_To (L_Index_Type (J), Loc))),
1052 Statements => New_List (
1055 Make_Assignment_Statement (Loc,
1056 Name => New_Occurrence_Of (Rnn (J), Loc),
1058 Make_Attribute_Reference (Loc,
1060 New_Occurrence_Of (R_Index_Type (J), Loc),
1061 Attribute_Name => S_Or_P,
1062 Expressions => New_List (
1063 New_Occurrence_Of (Rnn (J), Loc)))))))));
1067 end Expand_Assign_Array_Loop;
1069 --------------------------
1070 -- Expand_Assign_Record --
1071 --------------------------
1073 -- The only processing required is in the change of representation
1074 -- case, where we must expand the assignment to a series of field
1075 -- by field assignments.
1077 procedure Expand_Assign_Record (N : Node_Id) is
1078 Lhs : constant Node_Id := Name (N);
1079 Rhs : Node_Id := Expression (N);
1082 -- If change of representation, then extract the real right hand
1083 -- side from the type conversion, and proceed with component-wise
1084 -- assignment, since the two types are not the same as far as the
1085 -- back end is concerned.
1087 if Change_Of_Representation (N) then
1088 Rhs := Expression (Rhs);
1090 -- If this may be a case of a large bit aligned component, then
1091 -- proceed with component-wise assignment, to avoid possible
1092 -- clobbering of other components sharing bits in the first or
1093 -- last byte of the component to be assigned.
1095 elsif Possible_Bit_Aligned_Component (Lhs)
1097 Possible_Bit_Aligned_Component (Rhs)
1101 -- If neither condition met, then nothing special to do, the back end
1102 -- can handle assignment of the entire component as a single entity.
1108 -- At this stage we know that we must do a component wise assignment
1111 Loc : constant Source_Ptr := Sloc (N);
1112 R_Typ : constant Entity_Id := Base_Type (Etype (Rhs));
1113 L_Typ : constant Entity_Id := Base_Type (Etype (Lhs));
1114 Decl : constant Node_Id := Declaration_Node (R_Typ);
1118 function Find_Component
1120 Comp : Entity_Id) return Entity_Id;
1121 -- Find the component with the given name in the underlying record
1122 -- declaration for Typ. We need to use the actual entity because
1123 -- the type may be private and resolution by identifier alone would
1126 function Make_Component_List_Assign
1128 U_U : Boolean := False) return List_Id;
1129 -- Returns a sequence of statements to assign the components that
1130 -- are referenced in the given component list. The flag U_U is
1131 -- used to force the usage of the inferred value of the variant
1132 -- part expression as the switch for the generated case statement.
1134 function Make_Field_Assign
1136 U_U : Boolean := False) return Node_Id;
1137 -- Given C, the entity for a discriminant or component, build an
1138 -- assignment for the corresponding field values. The flag U_U
1139 -- signals the presence of an Unchecked_Union and forces the usage
1140 -- of the inferred discriminant value of C as the right hand side
1141 -- of the assignment.
1143 function Make_Field_Assigns (CI : List_Id) return List_Id;
1144 -- Given CI, a component items list, construct series of statements
1145 -- for fieldwise assignment of the corresponding components.
1147 --------------------
1148 -- Find_Component --
1149 --------------------
1151 function Find_Component
1153 Comp : Entity_Id) return Entity_Id
1155 Utyp : constant Entity_Id := Underlying_Type (Typ);
1159 C := First_Entity (Utyp);
1161 while Present (C) loop
1162 if Chars (C) = Chars (Comp) then
1168 raise Program_Error;
1171 --------------------------------
1172 -- Make_Component_List_Assign --
1173 --------------------------------
1175 function Make_Component_List_Assign
1177 U_U : Boolean := False) return List_Id
1179 CI : constant List_Id := Component_Items (CL);
1180 VP : constant Node_Id := Variant_Part (CL);
1190 Result := Make_Field_Assigns (CI);
1192 if Present (VP) then
1194 V := First_Non_Pragma (Variants (VP));
1196 while Present (V) loop
1199 DC := First (Discrete_Choices (V));
1200 while Present (DC) loop
1201 Append_To (DCH, New_Copy_Tree (DC));
1206 Make_Case_Statement_Alternative (Loc,
1207 Discrete_Choices => DCH,
1209 Make_Component_List_Assign (Component_List (V))));
1210 Next_Non_Pragma (V);
1213 -- If we have an Unchecked_Union, use the value of the inferred
1214 -- discriminant of the variant part expression as the switch
1215 -- for the case statement. The case statement may later be
1220 New_Copy (Get_Discriminant_Value (
1223 Discriminant_Constraint (Etype (Rhs))));
1226 Make_Selected_Component (Loc,
1227 Prefix => Duplicate_Subexpr (Rhs),
1229 Make_Identifier (Loc, Chars (Name (VP))));
1233 Make_Case_Statement (Loc,
1235 Alternatives => Alts));
1239 end Make_Component_List_Assign;
1241 -----------------------
1242 -- Make_Field_Assign --
1243 -----------------------
1245 function Make_Field_Assign
1247 U_U : Boolean := False) return Node_Id
1253 -- In the case of an Unchecked_Union, use the discriminant
1254 -- constraint value as on the right hand side of the assignment.
1258 New_Copy (Get_Discriminant_Value (C,
1260 Discriminant_Constraint (Etype (Rhs))));
1263 Make_Selected_Component (Loc,
1264 Prefix => Duplicate_Subexpr (Rhs),
1265 Selector_Name => New_Occurrence_Of (C, Loc));
1269 Make_Assignment_Statement (Loc,
1271 Make_Selected_Component (Loc,
1272 Prefix => Duplicate_Subexpr (Lhs),
1274 New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
1275 Expression => Expr);
1277 -- Set Assignment_OK, so discriminants can be assigned
1279 Set_Assignment_OK (Name (A), True);
1281 end Make_Field_Assign;
1283 ------------------------
1284 -- Make_Field_Assigns --
1285 ------------------------
1287 function Make_Field_Assigns (CI : List_Id) return List_Id is
1294 while Present (Item) loop
1295 if Nkind (Item) = N_Component_Declaration then
1297 (Result, Make_Field_Assign (Defining_Identifier (Item)));
1304 end Make_Field_Assigns;
1306 -- Start of processing for Expand_Assign_Record
1309 -- Note that we use the base types for this processing. This results
1310 -- in some extra work in the constrained case, but the change of
1311 -- representation case is so unusual that it is not worth the effort.
1313 -- First copy the discriminants. This is done unconditionally. It
1314 -- is required in the unconstrained left side case, and also in the
1315 -- case where this assignment was constructed during the expansion
1316 -- of a type conversion (since initialization of discriminants is
1317 -- suppressed in this case). It is unnecessary but harmless in
1320 if Has_Discriminants (L_Typ) then
1321 F := First_Discriminant (R_Typ);
1322 while Present (F) loop
1324 if Is_Unchecked_Union (Base_Type (R_Typ)) then
1325 Insert_Action (N, Make_Field_Assign (F, True));
1327 Insert_Action (N, Make_Field_Assign (F));
1330 Next_Discriminant (F);
1334 -- We know the underlying type is a record, but its current view
1335 -- may be private. We must retrieve the usable record declaration.
1337 if Nkind (Decl) = N_Private_Type_Declaration
1338 and then Present (Full_View (R_Typ))
1340 RDef := Type_Definition (Declaration_Node (Full_View (R_Typ)));
1342 RDef := Type_Definition (Decl);
1345 if Nkind (RDef) = N_Record_Definition
1346 and then Present (Component_List (RDef))
1349 if Is_Unchecked_Union (R_Typ) then
1351 Make_Component_List_Assign (Component_List (RDef), True));
1354 (N, Make_Component_List_Assign (Component_List (RDef)));
1357 Rewrite (N, Make_Null_Statement (Loc));
1361 end Expand_Assign_Record;
1363 -----------------------------------
1364 -- Expand_N_Assignment_Statement --
1365 -----------------------------------
1367 -- This procedure implements various cases where an assignment statement
1368 -- cannot just be passed on to the back end in untransformed state.
1370 procedure Expand_N_Assignment_Statement (N : Node_Id) is
1371 Loc : constant Source_Ptr := Sloc (N);
1372 Lhs : constant Node_Id := Name (N);
1373 Rhs : constant Node_Id := Expression (N);
1374 Typ : constant Entity_Id := Underlying_Type (Etype (Lhs));
1378 -- First deal with generation of range check if required. For now
1379 -- we do this only for discrete types.
1381 if Do_Range_Check (Rhs)
1382 and then Is_Discrete_Type (Typ)
1384 Set_Do_Range_Check (Rhs, False);
1385 Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed);
1388 -- Check for a special case where a high level transformation is
1389 -- required. If we have either of:
1394 -- where P is a reference to a bit packed array, then we have to unwind
1395 -- the assignment. The exact meaning of being a reference to a bit
1396 -- packed array is as follows:
1398 -- An indexed component whose prefix is a bit packed array is a
1399 -- reference to a bit packed array.
1401 -- An indexed component or selected component whose prefix is a
1402 -- reference to a bit packed array is itself a reference ot a
1403 -- bit packed array.
1405 -- The required transformation is
1407 -- Tnn : prefix_type := P;
1408 -- Tnn.field := rhs;
1413 -- Tnn : prefix_type := P;
1414 -- Tnn (subscr) := rhs;
1417 -- Since P is going to be evaluated more than once, any subscripts
1418 -- in P must have their evaluation forced.
1420 if (Nkind (Lhs) = N_Indexed_Component
1422 Nkind (Lhs) = N_Selected_Component)
1423 and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs))
1426 BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs));
1427 BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr);
1428 Tnn : constant Entity_Id :=
1429 Make_Defining_Identifier (Loc,
1430 Chars => New_Internal_Name ('T'));
1433 -- Insert the post assignment first, because we want to copy
1434 -- the BPAR_Expr tree before it gets analyzed in the context
1435 -- of the pre assignment. Note that we do not analyze the
1436 -- post assignment yet (we cannot till we have completed the
1437 -- analysis of the pre assignment). As usual, the analysis
1438 -- of this post assignment will happen on its own when we
1439 -- "run into" it after finishing the current assignment.
1442 Make_Assignment_Statement (Loc,
1443 Name => New_Copy_Tree (BPAR_Expr),
1444 Expression => New_Occurrence_Of (Tnn, Loc)));
1446 -- At this stage BPAR_Expr is a reference to a bit packed
1447 -- array where the reference was not expanded in the original
1448 -- tree, since it was on the left side of an assignment. But
1449 -- in the pre-assignment statement (the object definition),
1450 -- BPAR_Expr will end up on the right hand side, and must be
1451 -- reexpanded. To achieve this, we reset the analyzed flag
1452 -- of all selected and indexed components down to the actual
1453 -- indexed component for the packed array.
1457 Set_Analyzed (Exp, False);
1459 if Nkind (Exp) = N_Selected_Component
1461 Nkind (Exp) = N_Indexed_Component
1463 Exp := Prefix (Exp);
1469 -- Now we can insert and analyze the pre-assignment
1471 -- If the right-hand side requires a transient scope, it has
1472 -- already been placed on the stack. However, the declaration is
1473 -- inserted in the tree outside of this scope, and must reflect
1474 -- the proper scope for its variable. This awkward bit is forced
1475 -- by the stricter scope discipline imposed by GCC 2.97.
1478 Uses_Transient_Scope : constant Boolean :=
1480 and then N = Node_To_Be_Wrapped;
1483 if Uses_Transient_Scope then
1484 New_Scope (Scope (Current_Scope));
1487 Insert_Before_And_Analyze (N,
1488 Make_Object_Declaration (Loc,
1489 Defining_Identifier => Tnn,
1490 Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc),
1491 Expression => BPAR_Expr));
1493 if Uses_Transient_Scope then
1498 -- Now fix up the original assignment and continue processing
1500 Rewrite (Prefix (Lhs),
1501 New_Occurrence_Of (Tnn, Loc));
1503 -- We do not need to reanalyze that assignment, and we do not need
1504 -- to worry about references to the temporary, but we do need to
1505 -- make sure that the temporary is not marked as a true constant
1506 -- since we now have a generate assignment to it!
1508 Set_Is_True_Constant (Tnn, False);
1512 -- When we have the appropriate type of aggregate in the
1513 -- expression (it has been determined during analysis of the
1514 -- aggregate by setting the delay flag), let's perform in place
1515 -- assignment and thus avoid creating a temporay.
1517 if Is_Delayed_Aggregate (Rhs) then
1518 Convert_Aggr_In_Assignment (N);
1519 Rewrite (N, Make_Null_Statement (Loc));
1524 -- Apply discriminant check if required. If Lhs is an access type
1525 -- to a designated type with discriminants, we must always check.
1527 if Has_Discriminants (Etype (Lhs)) then
1529 -- Skip discriminant check if change of representation. Will be
1530 -- done when the change of representation is expanded out.
1532 if not Change_Of_Representation (N) then
1533 Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs);
1536 -- If the type is private without discriminants, and the full type
1537 -- has discriminants (necessarily with defaults) a check may still be
1538 -- necessary if the Lhs is aliased. The private determinants must be
1539 -- visible to build the discriminant constraints.
1541 -- Only an explicit dereference that comes from source indicates
1542 -- aliasing. Access to formals of protected operations and entries
1543 -- create dereferences but are not semantic aliasings.
1545 elsif Is_Private_Type (Etype (Lhs))
1546 and then Has_Discriminants (Typ)
1547 and then Nkind (Lhs) = N_Explicit_Dereference
1548 and then Comes_From_Source (Lhs)
1551 Lt : constant Entity_Id := Etype (Lhs);
1553 Set_Etype (Lhs, Typ);
1554 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1555 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1556 Set_Etype (Lhs, Lt);
1559 -- If the Lhs has a private type with unknown discriminants, it
1560 -- may have a full view with discriminants, but those are nameable
1561 -- only in the underlying type, so convert the Rhs to it before
1562 -- potential checking.
1564 elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs)))
1565 and then Has_Discriminants (Typ)
1567 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1568 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1570 -- In the access type case, we need the same discriminant check,
1571 -- and also range checks if we have an access to constrained array.
1573 elsif Is_Access_Type (Etype (Lhs))
1574 and then Is_Constrained (Designated_Type (Etype (Lhs)))
1576 if Has_Discriminants (Designated_Type (Etype (Lhs))) then
1578 -- Skip discriminant check if change of representation. Will be
1579 -- done when the change of representation is expanded out.
1581 if not Change_Of_Representation (N) then
1582 Apply_Discriminant_Check (Rhs, Etype (Lhs));
1585 elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then
1586 Apply_Range_Check (Rhs, Etype (Lhs));
1588 if Is_Constrained (Etype (Lhs)) then
1589 Apply_Length_Check (Rhs, Etype (Lhs));
1592 if Nkind (Rhs) = N_Allocator then
1594 Target_Typ : constant Entity_Id := Etype (Expression (Rhs));
1595 C_Es : Check_Result;
1602 Etype (Designated_Type (Etype (Lhs))));
1614 -- Apply range check for access type case
1616 elsif Is_Access_Type (Etype (Lhs))
1617 and then Nkind (Rhs) = N_Allocator
1618 and then Nkind (Expression (Rhs)) = N_Qualified_Expression
1620 Analyze_And_Resolve (Expression (Rhs));
1622 (Expression (Rhs), Designated_Type (Etype (Lhs)));
1625 -- Ada 2005 (AI-231): Generate the run-time check
1627 if Is_Access_Type (Typ)
1628 and then Can_Never_Be_Null (Etype (Lhs))
1629 and then not Can_Never_Be_Null (Etype (Rhs))
1631 Apply_Constraint_Check (Rhs, Etype (Lhs));
1634 -- If we are assigning an access type and the left side is an
1635 -- entity, then make sure that Is_Known_Non_Null properly
1636 -- reflects the state of the entity after the assignment
1638 if Is_Access_Type (Typ)
1639 and then Is_Entity_Name (Lhs)
1640 and then Known_Non_Null (Rhs)
1641 and then Safe_To_Capture_Value (N, Entity (Lhs))
1643 Set_Is_Known_Non_Null (Entity (Lhs), Known_Non_Null (Rhs));
1646 -- Case of assignment to a bit packed array element
1648 if Nkind (Lhs) = N_Indexed_Component
1649 and then Is_Bit_Packed_Array (Etype (Prefix (Lhs)))
1651 Expand_Bit_Packed_Element_Set (N);
1654 elsif Is_Tagged_Type (Typ)
1655 or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ))
1657 Tagged_Case : declare
1658 L : List_Id := No_List;
1659 Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N);
1662 -- In the controlled case, we need to make sure that function
1663 -- calls are evaluated before finalizing the target. In all
1664 -- cases, it makes the expansion easier if the side-effects
1665 -- are removed first.
1667 Remove_Side_Effects (Lhs);
1668 Remove_Side_Effects (Rhs);
1670 -- Avoid recursion in the mechanism
1674 -- If dispatching assignment, we need to dispatch to _assign
1676 if Is_Class_Wide_Type (Typ)
1678 -- If the type is tagged, we may as well use the predefined
1679 -- primitive assignment. This avoids inlining a lot of code
1680 -- and in the class-wide case, the assignment is replaced by
1681 -- dispatch call to _assign. Note that this cannot be done
1682 -- when discriminant checks are locally suppressed (as in
1683 -- extension aggregate expansions) because otherwise the
1684 -- discriminant check will be performed within the _assign
1685 -- call. It is also suppressed for assignmments created by the
1686 -- expander that correspond to initializations, where we do
1687 -- want to copy the tag (No_Ctrl_Actions flag set True).
1688 -- by the expander and we do not need to mess with tags ever
1689 -- (Expand_Ctrl_Actions flag is set True in this case).
1691 or else (Is_Tagged_Type (Typ)
1692 and then Chars (Current_Scope) /= Name_uAssign
1693 and then Expand_Ctrl_Actions
1694 and then not Discriminant_Checks_Suppressed (Empty))
1696 -- Fetch the primitive op _assign and proper type to call
1697 -- it. Because of possible conflits between private and
1698 -- full view the proper type is fetched directly from the
1699 -- operation profile.
1702 Op : constant Entity_Id :=
1703 Find_Prim_Op (Typ, Name_uAssign);
1704 F_Typ : Entity_Id := Etype (First_Formal (Op));
1707 -- If the assignment is dispatching, make sure to use the
1708 -- ??? where is rest of this comment ???
1710 if Is_Class_Wide_Type (Typ) then
1711 F_Typ := Class_Wide_Type (F_Typ);
1715 Make_Procedure_Call_Statement (Loc,
1716 Name => New_Reference_To (Op, Loc),
1717 Parameter_Associations => New_List (
1718 Unchecked_Convert_To (F_Typ, Duplicate_Subexpr (Lhs)),
1719 Unchecked_Convert_To (F_Typ,
1720 Duplicate_Subexpr (Rhs)))));
1724 L := Make_Tag_Ctrl_Assignment (N);
1726 -- We can't afford to have destructive Finalization Actions
1727 -- in the Self assignment case, so if the target and the
1728 -- source are not obviously different, code is generated to
1729 -- avoid the self assignment case
1731 -- if lhs'address /= rhs'address then
1732 -- <code for controlled and/or tagged assignment>
1735 if not Statically_Different (Lhs, Rhs)
1736 and then Expand_Ctrl_Actions
1739 Make_Implicit_If_Statement (N,
1743 Make_Attribute_Reference (Loc,
1744 Prefix => Duplicate_Subexpr (Lhs),
1745 Attribute_Name => Name_Address),
1748 Make_Attribute_Reference (Loc,
1749 Prefix => Duplicate_Subexpr (Rhs),
1750 Attribute_Name => Name_Address)),
1752 Then_Statements => L));
1755 -- We need to set up an exception handler for implementing
1756 -- 7.6.1 (18). The remaining adjustments are tackled by the
1757 -- implementation of adjust for record_controllers (see
1760 -- This is skipped if we have no finalization
1762 if Expand_Ctrl_Actions
1763 and then not Restriction_Active (No_Finalization)
1766 Make_Block_Statement (Loc,
1767 Handled_Statement_Sequence =>
1768 Make_Handled_Sequence_Of_Statements (Loc,
1770 Exception_Handlers => New_List (
1771 Make_Exception_Handler (Loc,
1772 Exception_Choices =>
1773 New_List (Make_Others_Choice (Loc)),
1774 Statements => New_List (
1775 Make_Raise_Program_Error (Loc,
1777 PE_Finalize_Raised_Exception)
1783 Make_Block_Statement (Loc,
1784 Handled_Statement_Sequence =>
1785 Make_Handled_Sequence_Of_Statements (Loc, Statements => L)));
1787 -- If no restrictions on aborts, protect the whole assignement
1788 -- for controlled objects as per 9.8(11)
1790 if Controlled_Type (Typ)
1791 and then Expand_Ctrl_Actions
1792 and then Abort_Allowed
1795 Blk : constant Entity_Id :=
1797 (E_Block, Current_Scope, Sloc (N), 'B');
1800 Set_Scope (Blk, Current_Scope);
1801 Set_Etype (Blk, Standard_Void_Type);
1802 Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N)));
1804 Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer));
1805 Set_At_End_Proc (Handled_Statement_Sequence (N),
1806 New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc));
1807 Expand_At_End_Handler
1808 (Handled_Statement_Sequence (N), Blk);
1812 -- N has been rewritten to a block statement for which it is
1813 -- known by construction that no checks are necessary: analyze
1814 -- it with all checks suppressed.
1816 Analyze (N, Suppress => All_Checks);
1822 elsif Is_Array_Type (Typ) then
1824 Actual_Rhs : Node_Id := Rhs;
1827 while Nkind (Actual_Rhs) = N_Type_Conversion
1829 Nkind (Actual_Rhs) = N_Qualified_Expression
1831 Actual_Rhs := Expression (Actual_Rhs);
1834 Expand_Assign_Array (N, Actual_Rhs);
1840 elsif Is_Record_Type (Typ) then
1841 Expand_Assign_Record (N);
1844 -- Scalar types. This is where we perform the processing related
1845 -- to the requirements of (RM 13.9.1(9-11)) concerning the handling
1846 -- of invalid scalar values.
1848 elsif Is_Scalar_Type (Typ) then
1850 -- Case where right side is known valid
1852 if Expr_Known_Valid (Rhs) then
1854 -- Here the right side is valid, so it is fine. The case to
1855 -- deal with is when the left side is a local variable reference
1856 -- whose value is not currently known to be valid. If this is
1857 -- the case, and the assignment appears in an unconditional
1858 -- context, then we can mark the left side as now being valid.
1860 if Is_Local_Variable_Reference (Lhs)
1861 and then not Is_Known_Valid (Entity (Lhs))
1862 and then In_Unconditional_Context (N)
1864 Set_Is_Known_Valid (Entity (Lhs), True);
1867 -- Case where right side may be invalid in the sense of the RM
1868 -- reference above. The RM does not require that we check for
1869 -- the validity on an assignment, but it does require that the
1870 -- assignment of an invalid value not cause erroneous behavior.
1872 -- The general approach in GNAT is to use the Is_Known_Valid flag
1873 -- to avoid the need for validity checking on assignments. However
1874 -- in some cases, we have to do validity checking in order to make
1875 -- sure that the setting of this flag is correct.
1878 -- Validate right side if we are validating copies
1880 if Validity_Checks_On
1881 and then Validity_Check_Copies
1885 -- We can propagate this to the left side where appropriate
1887 if Is_Local_Variable_Reference (Lhs)
1888 and then not Is_Known_Valid (Entity (Lhs))
1889 and then In_Unconditional_Context (N)
1891 Set_Is_Known_Valid (Entity (Lhs), True);
1894 -- Otherwise check to see what should be done
1896 -- If left side is a local variable, then we just set its
1897 -- flag to indicate that its value may no longer be valid,
1898 -- since we are copying a potentially invalid value.
1900 elsif Is_Local_Variable_Reference (Lhs) then
1901 Set_Is_Known_Valid (Entity (Lhs), False);
1903 -- Check for case of a nonlocal variable on the left side
1904 -- which is currently known to be valid. In this case, we
1905 -- simply ensure that the right side is valid. We only play
1906 -- the game of copying validity status for local variables,
1907 -- since we are doing this statically, not by tracing the
1910 elsif Is_Entity_Name (Lhs)
1911 and then Is_Known_Valid (Entity (Lhs))
1913 -- Note that the Ensure_Valid call is ignored if the
1914 -- Validity_Checking mode is set to none so we do not
1915 -- need to worry about that case here.
1919 -- In all other cases, we can safely copy an invalid value
1920 -- without worrying about the status of the left side. Since
1921 -- it is not a variable reference it will not be considered
1922 -- as being known to be valid in any case.
1930 -- Defend against invalid subscripts on left side if we are in
1931 -- standard validity checking mode. No need to do this if we
1932 -- are checking all subscripts.
1934 if Validity_Checks_On
1935 and then Validity_Check_Default
1936 and then not Validity_Check_Subscripts
1938 Check_Valid_Lvalue_Subscripts (Lhs);
1942 when RE_Not_Available =>
1944 end Expand_N_Assignment_Statement;
1946 ------------------------------
1947 -- Expand_N_Block_Statement --
1948 ------------------------------
1950 -- Encode entity names defined in block statement
1952 procedure Expand_N_Block_Statement (N : Node_Id) is
1954 Qualify_Entity_Names (N);
1955 end Expand_N_Block_Statement;
1957 -----------------------------
1958 -- Expand_N_Case_Statement --
1959 -----------------------------
1961 procedure Expand_N_Case_Statement (N : Node_Id) is
1962 Loc : constant Source_Ptr := Sloc (N);
1963 Expr : constant Node_Id := Expression (N);
1971 -- Check for the situation where we know at compile time which
1972 -- branch will be taken
1974 if Compile_Time_Known_Value (Expr) then
1975 Alt := Find_Static_Alternative (N);
1977 -- Move the statements from this alternative after the case
1978 -- statement. They are already analyzed, so will be skipped
1981 Insert_List_After (N, Statements (Alt));
1983 -- That leaves the case statement as a shell. The alternative
1984 -- that will be executed is reset to a null list. So now we can
1985 -- kill the entire case statement.
1987 Kill_Dead_Code (Expression (N));
1988 Kill_Dead_Code (Alternatives (N));
1989 Rewrite (N, Make_Null_Statement (Loc));
1993 -- Here if the choice is not determined at compile time
1996 Last_Alt : constant Node_Id := Last (Alternatives (N));
1998 Others_Present : Boolean;
1999 Others_Node : Node_Id;
2001 Then_Stms : List_Id;
2002 Else_Stms : List_Id;
2005 if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then
2006 Others_Present := True;
2007 Others_Node := Last_Alt;
2009 Others_Present := False;
2012 -- First step is to worry about possible invalid argument. The RM
2013 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
2014 -- outside the base range), then Constraint_Error must be raised.
2016 -- Case of validity check required (validity checks are on, the
2017 -- expression is not known to be valid, and the case statement
2018 -- comes from source -- no need to validity check internally
2019 -- generated case statements).
2021 if Validity_Check_Default then
2022 Ensure_Valid (Expr);
2025 -- If there is only a single alternative, just replace it with
2026 -- the sequence of statements since obviously that is what is
2027 -- going to be executed in all cases.
2029 Len := List_Length (Alternatives (N));
2032 -- We still need to evaluate the expression if it has any
2035 Remove_Side_Effects (Expression (N));
2037 Insert_List_After (N, Statements (First (Alternatives (N))));
2039 -- That leaves the case statement as a shell. The alternative
2040 -- that will be executed is reset to a null list. So now we can
2041 -- kill the entire case statement.
2043 Kill_Dead_Code (Expression (N));
2044 Rewrite (N, Make_Null_Statement (Loc));
2048 -- An optimization. If there are only two alternatives, and only
2049 -- a single choice, then rewrite the whole case statement as an
2050 -- if statement, since this can result in susbequent optimizations.
2051 -- This helps not only with case statements in the source of a
2052 -- simple form, but also with generated code (discriminant check
2053 -- functions in particular)
2056 Chlist := Discrete_Choices (First (Alternatives (N)));
2058 if List_Length (Chlist) = 1 then
2059 Choice := First (Chlist);
2061 Then_Stms := Statements (First (Alternatives (N)));
2062 Else_Stms := Statements (Last (Alternatives (N)));
2064 -- For TRUE, generate "expression", not expression = true
2066 if Nkind (Choice) = N_Identifier
2067 and then Entity (Choice) = Standard_True
2069 Cond := Expression (N);
2071 -- For FALSE, generate "expression" and switch then/else
2073 elsif Nkind (Choice) = N_Identifier
2074 and then Entity (Choice) = Standard_False
2076 Cond := Expression (N);
2077 Else_Stms := Statements (First (Alternatives (N)));
2078 Then_Stms := Statements (Last (Alternatives (N)));
2080 -- For a range, generate "expression in range"
2082 elsif Nkind (Choice) = N_Range
2083 or else (Nkind (Choice) = N_Attribute_Reference
2084 and then Attribute_Name (Choice) = Name_Range)
2085 or else (Is_Entity_Name (Choice)
2086 and then Is_Type (Entity (Choice)))
2087 or else Nkind (Choice) = N_Subtype_Indication
2091 Left_Opnd => Expression (N),
2092 Right_Opnd => Relocate_Node (Choice));
2094 -- For any other subexpression "expression = value"
2099 Left_Opnd => Expression (N),
2100 Right_Opnd => Relocate_Node (Choice));
2103 -- Now rewrite the case as an IF
2106 Make_If_Statement (Loc,
2108 Then_Statements => Then_Stms,
2109 Else_Statements => Else_Stms));
2115 -- If the last alternative is not an Others choice, replace it
2116 -- with an N_Others_Choice. Note that we do not bother to call
2117 -- Analyze on the modified case statement, since it's only effect
2118 -- would be to compute the contents of the Others_Discrete_Choices
2119 -- which is not needed by the back end anyway.
2121 -- The reason we do this is that the back end always needs some
2122 -- default for a switch, so if we have not supplied one in the
2123 -- processing above for validity checking, then we need to
2126 if not Others_Present then
2127 Others_Node := Make_Others_Choice (Sloc (Last_Alt));
2128 Set_Others_Discrete_Choices
2129 (Others_Node, Discrete_Choices (Last_Alt));
2130 Set_Discrete_Choices (Last_Alt, New_List (Others_Node));
2133 end Expand_N_Case_Statement;
2135 -----------------------------
2136 -- Expand_N_Exit_Statement --
2137 -----------------------------
2139 -- The only processing required is to deal with a possible C/Fortran
2140 -- boolean value used as the condition for the exit statement.
2142 procedure Expand_N_Exit_Statement (N : Node_Id) is
2144 Adjust_Condition (Condition (N));
2145 end Expand_N_Exit_Statement;
2147 -----------------------------
2148 -- Expand_N_Goto_Statement --
2149 -----------------------------
2151 -- Add poll before goto if polling active
2153 procedure Expand_N_Goto_Statement (N : Node_Id) is
2155 Generate_Poll_Call (N);
2156 end Expand_N_Goto_Statement;
2158 ---------------------------
2159 -- Expand_N_If_Statement --
2160 ---------------------------
2162 -- First we deal with the case of C and Fortran convention boolean
2163 -- values, with zero/non-zero semantics.
2165 -- Second, we deal with the obvious rewriting for the cases where the
2166 -- condition of the IF is known at compile time to be True or False.
2168 -- Third, we remove elsif parts which have non-empty Condition_Actions
2169 -- and rewrite as independent if statements. For example:
2180 -- <<condition actions of y>>
2186 -- This rewriting is needed if at least one elsif part has a non-empty
2187 -- Condition_Actions list. We also do the same processing if there is
2188 -- a constant condition in an elsif part (in conjunction with the first
2189 -- processing step mentioned above, for the recursive call made to deal
2190 -- with the created inner if, this deals with properly optimizing the
2191 -- cases of constant elsif conditions).
2193 procedure Expand_N_If_Statement (N : Node_Id) is
2194 Loc : constant Source_Ptr := Sloc (N);
2200 Adjust_Condition (Condition (N));
2202 -- The following loop deals with constant conditions for the IF. We
2203 -- need a loop because as we eliminate False conditions, we grab the
2204 -- first elsif condition and use it as the primary condition.
2206 while Compile_Time_Known_Value (Condition (N)) loop
2208 -- If condition is True, we can simply rewrite the if statement
2209 -- now by replacing it by the series of then statements.
2211 if Is_True (Expr_Value (Condition (N))) then
2213 -- All the else parts can be killed
2215 Kill_Dead_Code (Elsif_Parts (N));
2216 Kill_Dead_Code (Else_Statements (N));
2218 Hed := Remove_Head (Then_Statements (N));
2219 Insert_List_After (N, Then_Statements (N));
2223 -- If condition is False, then we can delete the condition and
2224 -- the Then statements
2227 -- We do not delete the condition if constant condition
2228 -- warnings are enabled, since otherwise we end up deleting
2229 -- the desired warning. Of course the backend will get rid
2230 -- of this True/False test anyway, so nothing is lost here.
2232 if not Constant_Condition_Warnings then
2233 Kill_Dead_Code (Condition (N));
2236 Kill_Dead_Code (Then_Statements (N));
2238 -- If there are no elsif statements, then we simply replace
2239 -- the entire if statement by the sequence of else statements.
2241 if No (Elsif_Parts (N)) then
2243 if No (Else_Statements (N))
2244 or else Is_Empty_List (Else_Statements (N))
2247 Make_Null_Statement (Sloc (N)));
2250 Hed := Remove_Head (Else_Statements (N));
2251 Insert_List_After (N, Else_Statements (N));
2257 -- If there are elsif statements, the first of them becomes
2258 -- the if/then section of the rebuilt if statement This is
2259 -- the case where we loop to reprocess this copied condition.
2262 Hed := Remove_Head (Elsif_Parts (N));
2263 Insert_Actions (N, Condition_Actions (Hed));
2264 Set_Condition (N, Condition (Hed));
2265 Set_Then_Statements (N, Then_Statements (Hed));
2267 -- Hed might have been captured as the condition determining
2268 -- the current value for an entity. Now it is detached from
2269 -- the tree, so a Current_Value pointer in the condition might
2270 -- need to be updated.
2272 Check_Possible_Current_Value_Condition (N);
2274 if Is_Empty_List (Elsif_Parts (N)) then
2275 Set_Elsif_Parts (N, No_List);
2281 -- Loop through elsif parts, dealing with constant conditions and
2282 -- possible expression actions that are present.
2284 if Present (Elsif_Parts (N)) then
2285 E := First (Elsif_Parts (N));
2286 while Present (E) loop
2287 Adjust_Condition (Condition (E));
2289 -- If there are condition actions, then we rewrite the if
2290 -- statement as indicated above. We also do the same rewrite
2291 -- if the condition is True or False. The further processing
2292 -- of this constant condition is then done by the recursive
2293 -- call to expand the newly created if statement
2295 if Present (Condition_Actions (E))
2296 or else Compile_Time_Known_Value (Condition (E))
2298 -- Note this is not an implicit if statement, since it is
2299 -- part of an explicit if statement in the source (or of an
2300 -- implicit if statement that has already been tested).
2303 Make_If_Statement (Sloc (E),
2304 Condition => Condition (E),
2305 Then_Statements => Then_Statements (E),
2306 Elsif_Parts => No_List,
2307 Else_Statements => Else_Statements (N));
2309 -- Elsif parts for new if come from remaining elsif's of parent
2311 while Present (Next (E)) loop
2312 if No (Elsif_Parts (New_If)) then
2313 Set_Elsif_Parts (New_If, New_List);
2316 Append (Remove_Next (E), Elsif_Parts (New_If));
2319 Set_Else_Statements (N, New_List (New_If));
2321 if Present (Condition_Actions (E)) then
2322 Insert_List_Before (New_If, Condition_Actions (E));
2327 if Is_Empty_List (Elsif_Parts (N)) then
2328 Set_Elsif_Parts (N, No_List);
2334 -- No special processing for that elsif part, move to next
2342 -- Some more optimizations applicable if we still have an IF statement
2344 if Nkind (N) /= N_If_Statement then
2348 -- Another optimization, special cases that can be simplified
2350 -- if expression then
2356 -- can be changed to:
2358 -- return expression;
2362 -- if expression then
2368 -- can be changed to:
2370 -- return not (expression);
2372 if Nkind (N) = N_If_Statement
2373 and then No (Elsif_Parts (N))
2374 and then Present (Else_Statements (N))
2375 and then List_Length (Then_Statements (N)) = 1
2376 and then List_Length (Else_Statements (N)) = 1
2379 Then_Stm : constant Node_Id := First (Then_Statements (N));
2380 Else_Stm : constant Node_Id := First (Else_Statements (N));
2383 if Nkind (Then_Stm) = N_Return_Statement
2385 Nkind (Else_Stm) = N_Return_Statement
2388 Then_Expr : constant Node_Id := Expression (Then_Stm);
2389 Else_Expr : constant Node_Id := Expression (Else_Stm);
2392 if Nkind (Then_Expr) = N_Identifier
2394 Nkind (Else_Expr) = N_Identifier
2396 if Entity (Then_Expr) = Standard_True
2397 and then Entity (Else_Expr) = Standard_False
2400 Make_Return_Statement (Loc,
2401 Expression => Relocate_Node (Condition (N))));
2405 elsif Entity (Then_Expr) = Standard_False
2406 and then Entity (Else_Expr) = Standard_True
2409 Make_Return_Statement (Loc,
2412 Right_Opnd => Relocate_Node (Condition (N)))));
2421 end Expand_N_If_Statement;
2423 -----------------------------
2424 -- Expand_N_Loop_Statement --
2425 -----------------------------
2427 -- 1. Deal with while condition for C/Fortran boolean
2428 -- 2. Deal with loops with a non-standard enumeration type range
2429 -- 3. Deal with while loops where Condition_Actions is set
2430 -- 4. Insert polling call if required
2432 procedure Expand_N_Loop_Statement (N : Node_Id) is
2433 Loc : constant Source_Ptr := Sloc (N);
2434 Isc : constant Node_Id := Iteration_Scheme (N);
2437 if Present (Isc) then
2438 Adjust_Condition (Condition (Isc));
2441 if Is_Non_Empty_List (Statements (N)) then
2442 Generate_Poll_Call (First (Statements (N)));
2449 -- Handle the case where we have a for loop with the range type being
2450 -- an enumeration type with non-standard representation. In this case
2453 -- for x in [reverse] a .. b loop
2459 -- for xP in [reverse] integer
2460 -- range etype'Pos (a) .. etype'Pos (b) loop
2462 -- x : constant etype := Pos_To_Rep (xP);
2468 if Present (Loop_Parameter_Specification (Isc)) then
2470 LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
2471 Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
2472 Ltype : constant Entity_Id := Etype (Loop_Id);
2473 Btype : constant Entity_Id := Base_Type (Ltype);
2478 if not Is_Enumeration_Type (Btype)
2479 or else No (Enum_Pos_To_Rep (Btype))
2485 Make_Defining_Identifier (Loc,
2486 Chars => New_External_Name (Chars (Loop_Id), 'P'));
2488 -- If the type has a contiguous representation, successive
2489 -- values can be generated as offsets from the first literal.
2491 if Has_Contiguous_Rep (Btype) then
2493 Unchecked_Convert_To (Btype,
2496 Make_Integer_Literal (Loc,
2497 Enumeration_Rep (First_Literal (Btype))),
2498 Right_Opnd => New_Reference_To (New_Id, Loc)));
2500 -- Use the constructed array Enum_Pos_To_Rep
2503 Make_Indexed_Component (Loc,
2504 Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc),
2505 Expressions => New_List (New_Reference_To (New_Id, Loc)));
2509 Make_Loop_Statement (Loc,
2510 Identifier => Identifier (N),
2513 Make_Iteration_Scheme (Loc,
2514 Loop_Parameter_Specification =>
2515 Make_Loop_Parameter_Specification (Loc,
2516 Defining_Identifier => New_Id,
2517 Reverse_Present => Reverse_Present (LPS),
2519 Discrete_Subtype_Definition =>
2520 Make_Subtype_Indication (Loc,
2523 New_Reference_To (Standard_Natural, Loc),
2526 Make_Range_Constraint (Loc,
2531 Make_Attribute_Reference (Loc,
2533 New_Reference_To (Btype, Loc),
2535 Attribute_Name => Name_Pos,
2537 Expressions => New_List (
2539 (Type_Low_Bound (Ltype)))),
2542 Make_Attribute_Reference (Loc,
2544 New_Reference_To (Btype, Loc),
2546 Attribute_Name => Name_Pos,
2548 Expressions => New_List (
2550 (Type_High_Bound (Ltype))))))))),
2552 Statements => New_List (
2553 Make_Block_Statement (Loc,
2554 Declarations => New_List (
2555 Make_Object_Declaration (Loc,
2556 Defining_Identifier => Loop_Id,
2557 Constant_Present => True,
2558 Object_Definition => New_Reference_To (Ltype, Loc),
2559 Expression => Expr)),
2561 Handled_Statement_Sequence =>
2562 Make_Handled_Sequence_Of_Statements (Loc,
2563 Statements => Statements (N)))),
2565 End_Label => End_Label (N)));
2569 -- Second case, if we have a while loop with Condition_Actions set,
2570 -- then we change it into a plain loop:
2579 -- <<condition actions>>
2585 and then Present (Condition_Actions (Isc))
2592 Make_Exit_Statement (Sloc (Condition (Isc)),
2594 Make_Op_Not (Sloc (Condition (Isc)),
2595 Right_Opnd => Condition (Isc)));
2597 Prepend (ES, Statements (N));
2598 Insert_List_Before (ES, Condition_Actions (Isc));
2600 -- This is not an implicit loop, since it is generated in
2601 -- response to the loop statement being processed. If this
2602 -- is itself implicit, the restriction has already been
2603 -- checked. If not, it is an explicit loop.
2606 Make_Loop_Statement (Sloc (N),
2607 Identifier => Identifier (N),
2608 Statements => Statements (N),
2609 End_Label => End_Label (N)));
2614 end Expand_N_Loop_Statement;
2616 -------------------------------
2617 -- Expand_N_Return_Statement --
2618 -------------------------------
2620 procedure Expand_N_Return_Statement (N : Node_Id) is
2621 Loc : constant Source_Ptr := Sloc (N);
2622 Exp : constant Node_Id := Expression (N);
2626 Scope_Id : Entity_Id;
2630 Goto_Stat : Node_Id;
2633 Return_Type : Entity_Id;
2634 Result_Exp : Node_Id;
2635 Result_Id : Entity_Id;
2636 Result_Obj : Node_Id;
2639 -- Case where returned expression is present
2641 if Present (Exp) then
2643 -- Always normalize C/Fortran boolean result. This is not always
2644 -- necessary, but it seems a good idea to minimize the passing
2645 -- around of non-normalized values, and in any case this handles
2646 -- the processing of barrier functions for protected types, which
2647 -- turn the condition into a return statement.
2649 Exptyp := Etype (Exp);
2651 if Is_Boolean_Type (Exptyp)
2652 and then Nonzero_Is_True (Exptyp)
2654 Adjust_Condition (Exp);
2655 Adjust_Result_Type (Exp, Exptyp);
2658 -- Do validity check if enabled for returns
2660 if Validity_Checks_On
2661 and then Validity_Check_Returns
2667 -- Find relevant enclosing scope from which return is returning
2669 Cur_Idx := Scope_Stack.Last;
2671 Scope_Id := Scope_Stack.Table (Cur_Idx).Entity;
2673 if Ekind (Scope_Id) /= E_Block
2674 and then Ekind (Scope_Id) /= E_Loop
2679 Cur_Idx := Cur_Idx - 1;
2680 pragma Assert (Cur_Idx >= 0);
2685 Kind := Ekind (Scope_Id);
2687 -- If it is a return from procedures do no extra steps
2689 if Kind = E_Procedure or else Kind = E_Generic_Procedure then
2693 pragma Assert (Is_Entry (Scope_Id));
2695 -- Look at the enclosing block to see whether the return is from
2696 -- an accept statement or an entry body.
2698 for J in reverse 0 .. Cur_Idx loop
2699 Scope_Id := Scope_Stack.Table (J).Entity;
2700 exit when Is_Concurrent_Type (Scope_Id);
2703 -- If it is a return from accept statement it should be expanded
2704 -- as a call to RTS Complete_Rendezvous and a goto to the end of
2707 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
2708 -- Expand_N_Accept_Alternative in exp_ch9.adb)
2710 if Is_Task_Type (Scope_Id) then
2712 Call := (Make_Procedure_Call_Statement (Loc,
2713 Name => New_Reference_To
2714 (RTE (RE_Complete_Rendezvous), Loc)));
2715 Insert_Before (N, Call);
2716 -- why not insert actions here???
2719 Acc_Stat := Parent (N);
2720 while Nkind (Acc_Stat) /= N_Accept_Statement loop
2721 Acc_Stat := Parent (Acc_Stat);
2724 Lab_Node := Last (Statements
2725 (Handled_Statement_Sequence (Acc_Stat)));
2727 Goto_Stat := Make_Goto_Statement (Loc,
2728 Name => New_Occurrence_Of
2729 (Entity (Identifier (Lab_Node)), Loc));
2731 Set_Analyzed (Goto_Stat);
2733 Rewrite (N, Goto_Stat);
2736 -- If it is a return from an entry body, put a Complete_Entry_Body
2737 -- call in front of the return.
2739 elsif Is_Protected_Type (Scope_Id) then
2742 Make_Procedure_Call_Statement (Loc,
2743 Name => New_Reference_To
2744 (RTE (RE_Complete_Entry_Body), Loc),
2745 Parameter_Associations => New_List
2746 (Make_Attribute_Reference (Loc,
2750 (Corresponding_Body (Parent (Scope_Id))),
2752 Attribute_Name => Name_Unchecked_Access)));
2754 Insert_Before (N, Call);
2763 Return_Type := Etype (Scope_Id);
2764 Utyp := Underlying_Type (Return_Type);
2766 -- Check the result expression of a scalar function against
2767 -- the subtype of the function by inserting a conversion.
2768 -- This conversion must eventually be performed for other
2769 -- classes of types, but for now it's only done for scalars.
2772 if Is_Scalar_Type (T) then
2773 Rewrite (Exp, Convert_To (Return_Type, Exp));
2777 -- Deal with returning variable length objects and controlled types
2779 -- Nothing to do if we are returning by reference, or this is not
2780 -- a type that requires special processing (indicated by the fact
2781 -- that it requires a cleanup scope for the secondary stack case)
2783 if Is_Return_By_Reference_Type (T) then
2786 elsif not Requires_Transient_Scope (Return_Type) then
2788 -- mutable records with no variable length components are not
2789 -- returned on the sec-stack so we need to make sure that the
2790 -- backend will only copy back the size of the actual value and not
2791 -- the maximum size. We create an actual subtype for this purpose
2794 Ubt : constant Entity_Id := Underlying_Type (Base_Type (T));
2798 if Has_Discriminants (Ubt)
2799 and then not Is_Constrained (Ubt)
2800 and then not Has_Unchecked_Union (Ubt)
2802 Decl := Build_Actual_Subtype (Ubt, Exp);
2803 Ent := Defining_Identifier (Decl);
2804 Insert_Action (Exp, Decl);
2805 Rewrite (Exp, Unchecked_Convert_To (Ent, Exp));
2809 -- Case of secondary stack not used
2811 elsif Function_Returns_With_DSP (Scope_Id) then
2813 -- Here what we need to do is to always return by reference, since
2814 -- we will return with the stack pointer depressed. We may need to
2815 -- do a copy to a local temporary before doing this return.
2817 No_Secondary_Stack_Case : declare
2818 Local_Copy_Required : Boolean := False;
2819 -- Set to True if a local copy is required
2821 Copy_Ent : Entity_Id;
2822 -- Used for the target entity if a copy is required
2825 -- Declaration used to create copy if needed
2827 procedure Test_Copy_Required (Expr : Node_Id);
2828 -- Determines if Expr represents a return value for which a
2829 -- copy is required. More specifically, a copy is not required
2830 -- if Expr represents an object or component of an object that
2831 -- is either in the local subprogram frame, or is constant.
2832 -- If a copy is required, then Local_Copy_Required is set True.
2834 ------------------------
2835 -- Test_Copy_Required --
2836 ------------------------
2838 procedure Test_Copy_Required (Expr : Node_Id) is
2842 -- If component, test prefix (object containing component)
2844 if Nkind (Expr) = N_Indexed_Component
2846 Nkind (Expr) = N_Selected_Component
2848 Test_Copy_Required (Prefix (Expr));
2851 -- See if we have an entity name
2853 elsif Is_Entity_Name (Expr) then
2854 Ent := Entity (Expr);
2856 -- Constant entity is always OK, no copy required
2858 if Ekind (Ent) = E_Constant then
2861 -- No copy required for local variable
2863 elsif Ekind (Ent) = E_Variable
2864 and then Scope (Ent) = Current_Subprogram
2870 -- All other cases require a copy
2872 Local_Copy_Required := True;
2873 end Test_Copy_Required;
2875 -- Start of processing for No_Secondary_Stack_Case
2878 -- No copy needed if result is from a function call.
2879 -- In this case the result is already being returned by
2880 -- reference with the stack pointer depressed.
2882 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2883 -- the copy for array types if the constrained status of the
2884 -- target type is different from that of the expression.
2886 if Requires_Transient_Scope (T)
2888 (not Is_Array_Type (T)
2889 or else Is_Constrained (T) = Is_Constrained (Return_Type)
2890 or else Controlled_Type (T))
2891 and then Nkind (Exp) = N_Function_Call
2895 -- We always need a local copy for a controlled type, since
2896 -- we are required to finalize the local value before return.
2897 -- The copy will automatically include the required finalize.
2898 -- Moreover, gigi cannot make this copy, since we need special
2899 -- processing to ensure proper behavior for finalization.
2901 -- Note: the reason we are returning with a depressed stack
2902 -- pointer in the controlled case (even if the type involved
2903 -- is constrained) is that we must make a local copy to deal
2904 -- properly with the requirement that the local result be
2907 elsif Controlled_Type (Utyp) then
2909 Make_Defining_Identifier (Loc,
2910 Chars => New_Internal_Name ('R'));
2912 -- Build declaration to do the copy, and insert it, setting
2913 -- Assignment_OK, because we may be copying a limited type.
2914 -- In addition we set the special flag to inhibit finalize
2915 -- attachment if this is a controlled type (since this attach
2916 -- must be done by the caller, otherwise if we attach it here
2917 -- we will finalize the returned result prematurely).
2920 Make_Object_Declaration (Loc,
2921 Defining_Identifier => Copy_Ent,
2922 Object_Definition => New_Occurrence_Of (Return_Type, Loc),
2923 Expression => Relocate_Node (Exp));
2925 Set_Assignment_OK (Decl);
2926 Set_Delay_Finalize_Attach (Decl);
2927 Insert_Action (N, Decl);
2929 -- Now the actual return uses the copied value
2931 Rewrite (Exp, New_Occurrence_Of (Copy_Ent, Loc));
2932 Analyze_And_Resolve (Exp, Return_Type);
2934 -- Since we have made the copy, gigi does not have to, so
2935 -- we set the By_Ref flag to prevent another copy being made.
2939 -- Non-controlled cases
2942 Test_Copy_Required (Exp);
2944 -- If a local copy is required, then gigi will make the
2945 -- copy, otherwise, we can return the result directly,
2946 -- so set By_Ref to suppress the gigi copy.
2948 if not Local_Copy_Required then
2952 end No_Secondary_Stack_Case;
2954 -- Here if secondary stack is used
2957 -- Make sure that no surrounding block will reclaim the
2958 -- secondary-stack on which we are going to put the result.
2959 -- Not only may this introduce secondary stack leaks but worse,
2960 -- if the reclamation is done too early, then the result we are
2961 -- returning may get clobbered. See example in 7417-003.
2964 S : Entity_Id := Current_Scope;
2967 while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop
2968 Set_Sec_Stack_Needed_For_Return (S, True);
2969 S := Enclosing_Dynamic_Scope (S);
2973 -- Optimize the case where the result is a function call. In this
2974 -- case either the result is already on the secondary stack, or is
2975 -- already being returned with the stack pointer depressed and no
2976 -- further processing is required except to set the By_Ref flag to
2977 -- ensure that gigi does not attempt an extra unnecessary copy.
2978 -- (actually not just unnecessary but harmfully wrong in the case
2979 -- of a controlled type, where gigi does not know how to do a copy).
2980 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2981 -- the copy for array types if the constrained status of the
2982 -- target type is different from that of the expression.
2984 if Requires_Transient_Scope (T)
2986 (not Is_Array_Type (T)
2987 or else Is_Constrained (T) = Is_Constrained (Return_Type)
2988 or else Controlled_Type (T))
2989 and then Nkind (Exp) = N_Function_Call
2993 -- Remove side effects from the expression now so that
2994 -- other part of the expander do not have to reanalyze
2995 -- this node without this optimization
2997 Rewrite (Exp, Duplicate_Subexpr_No_Checks (Exp));
2999 -- For controlled types, do the allocation on the sec-stack
3000 -- manually in order to call adjust at the right time
3001 -- type Anon1 is access Return_Type;
3002 -- for Anon1'Storage_pool use ss_pool;
3003 -- Anon2 : anon1 := new Return_Type'(expr);
3004 -- return Anon2.all;
3006 elsif Controlled_Type (Utyp) then
3008 Loc : constant Source_Ptr := Sloc (N);
3009 Temp : constant Entity_Id :=
3010 Make_Defining_Identifier (Loc,
3011 Chars => New_Internal_Name ('R'));
3012 Acc_Typ : constant Entity_Id :=
3013 Make_Defining_Identifier (Loc,
3014 Chars => New_Internal_Name ('A'));
3015 Alloc_Node : Node_Id;
3018 Set_Ekind (Acc_Typ, E_Access_Type);
3020 Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool));
3023 Make_Allocator (Loc,
3025 Make_Qualified_Expression (Loc,
3026 Subtype_Mark => New_Reference_To (Etype (Exp), Loc),
3027 Expression => Relocate_Node (Exp)));
3029 Insert_List_Before_And_Analyze (N, New_List (
3030 Make_Full_Type_Declaration (Loc,
3031 Defining_Identifier => Acc_Typ,
3033 Make_Access_To_Object_Definition (Loc,
3034 Subtype_Indication =>
3035 New_Reference_To (Return_Type, Loc))),
3037 Make_Object_Declaration (Loc,
3038 Defining_Identifier => Temp,
3039 Object_Definition => New_Reference_To (Acc_Typ, Loc),
3040 Expression => Alloc_Node)));
3043 Make_Explicit_Dereference (Loc,
3044 Prefix => New_Reference_To (Temp, Loc)));
3046 Analyze_And_Resolve (Exp, Return_Type);
3049 -- Otherwise use the gigi mechanism to allocate result on the
3053 Set_Storage_Pool (N, RTE (RE_SS_Pool));
3055 -- If we are generating code for the Java VM do not use
3056 -- SS_Allocate since everything is heap-allocated anyway.
3059 Set_Procedure_To_Call (N, RTE (RE_SS_Allocate));
3064 -- Implement the rules of 6.5(8-10), which require a tag check in
3065 -- the case of a limited tagged return type, and tag reassignment
3066 -- for nonlimited tagged results. These actions are needed when
3067 -- the return type is a specific tagged type and the result
3068 -- expression is a conversion or a formal parameter, because in
3069 -- that case the tag of the expression might differ from the tag
3070 -- of the specific result type.
3072 if Is_Tagged_Type (Utyp)
3073 and then not Is_Class_Wide_Type (Utyp)
3074 and then (Nkind (Exp) = N_Type_Conversion
3075 or else Nkind (Exp) = N_Unchecked_Type_Conversion
3076 or else (Is_Entity_Name (Exp)
3077 and then Ekind (Entity (Exp)) in Formal_Kind))
3079 -- When the return type is limited, perform a check that the
3080 -- tag of the result is the same as the tag of the return type.
3082 if Is_Limited_Type (Return_Type) then
3084 Make_Raise_Constraint_Error (Loc,
3088 Make_Selected_Component (Loc,
3089 Prefix => Duplicate_Subexpr (Exp),
3091 New_Reference_To (First_Tag_Component (Utyp), Loc)),
3093 Unchecked_Convert_To (RTE (RE_Tag),
3096 (Access_Disp_Table (Base_Type (Utyp)))),
3098 Reason => CE_Tag_Check_Failed));
3100 -- If the result type is a specific nonlimited tagged type,
3101 -- then we have to ensure that the tag of the result is that
3102 -- of the result type. This is handled by making a copy of the
3103 -- expression in the case where it might have a different tag,
3104 -- namely when the expression is a conversion or a formal
3105 -- parameter. We create a new object of the result type and
3106 -- initialize it from the expression, which will implicitly
3107 -- force the tag to be set appropriately.
3111 Make_Defining_Identifier (Loc, New_Internal_Name ('R'));
3112 Result_Exp := New_Reference_To (Result_Id, Loc);
3115 Make_Object_Declaration (Loc,
3116 Defining_Identifier => Result_Id,
3117 Object_Definition => New_Reference_To (Return_Type, Loc),
3118 Constant_Present => True,
3119 Expression => Relocate_Node (Exp));
3121 Set_Assignment_OK (Result_Obj);
3122 Insert_Action (Exp, Result_Obj);
3124 Rewrite (Exp, Result_Exp);
3125 Analyze_And_Resolve (Exp, Return_Type);
3128 -- Ada 2005 (AI-344): If the result type is class-wide, then insert
3129 -- a check that the level of the return expression's underlying type
3130 -- is not deeper than the level of the master enclosing the function.
3131 -- Always generate the check when the type of the return expression
3132 -- is class-wide, when it's a type conversion, or when it's a formal
3133 -- parameter. Otherwise, suppress the check in the case where the
3134 -- return expression has a specific type whose level is known not to
3135 -- be statically deeper than the function's result type.
3137 elsif Ada_Version >= Ada_05
3138 and then Is_Class_Wide_Type (Return_Type)
3139 and then not Scope_Suppress (Accessibility_Check)
3141 (Is_Class_Wide_Type (Etype (Exp))
3142 or else Nkind (Exp) = N_Type_Conversion
3143 or else Nkind (Exp) = N_Unchecked_Type_Conversion
3144 or else (Is_Entity_Name (Exp)
3145 and then Ekind (Entity (Exp)) in Formal_Kind)
3146 or else Scope_Depth (Enclosing_Dynamic_Scope (Etype (Exp))) >
3147 Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))
3150 Make_Raise_Program_Error (Loc,
3154 Make_Function_Call (Loc,
3157 (RTE (RE_Get_Access_Level), Loc),
3158 Parameter_Associations =>
3159 New_List (Make_Attribute_Reference (Loc,
3161 Duplicate_Subexpr (Exp),
3165 Make_Integer_Literal (Loc,
3166 Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))),
3167 Reason => PE_Accessibility_Check_Failed));
3171 when RE_Not_Available =>
3173 end Expand_N_Return_Statement;
3175 ------------------------------
3176 -- Make_Tag_Ctrl_Assignment --
3177 ------------------------------
3179 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is
3180 Loc : constant Source_Ptr := Sloc (N);
3181 L : constant Node_Id := Name (N);
3182 T : constant Entity_Id := Underlying_Type (Etype (L));
3184 Ctrl_Act : constant Boolean := Controlled_Type (T)
3185 and then not No_Ctrl_Actions (N);
3187 Save_Tag : constant Boolean := Is_Tagged_Type (T)
3188 and then not No_Ctrl_Actions (N)
3189 and then not Java_VM;
3190 -- Tags are not saved and restored when Java_VM because JVM tags
3191 -- are represented implicitly in objects.
3194 Tag_Tmp : Entity_Id;
3199 -- Finalize the target of the assignment when controlled.
3200 -- We have two exceptions here:
3202 -- 1. If we are in an init proc since it is an initialization
3203 -- more than an assignment
3205 -- 2. If the left-hand side is a temporary that was not initialized
3206 -- (or the parent part of a temporary since it is the case in
3207 -- extension aggregates). Such a temporary does not come from
3208 -- source. We must examine the original node for the prefix, because
3209 -- it may be a component of an entry formal, in which case it has
3210 -- been rewritten and does not appear to come from source either.
3212 -- Case of init proc
3214 if not Ctrl_Act then
3217 -- The left hand side is an uninitialized temporary
3219 elsif Nkind (L) = N_Type_Conversion
3220 and then Is_Entity_Name (Expression (L))
3221 and then No_Initialization (Parent (Entity (Expression (L))))
3225 Append_List_To (Res,
3227 Ref => Duplicate_Subexpr_No_Checks (L),
3229 With_Detach => New_Reference_To (Standard_False, Loc)));
3232 -- Save the Tag in a local variable Tag_Tmp
3236 Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
3239 Make_Object_Declaration (Loc,
3240 Defining_Identifier => Tag_Tmp,
3241 Object_Definition => New_Reference_To (RTE (RE_Tag), Loc),
3243 Make_Selected_Component (Loc,
3244 Prefix => Duplicate_Subexpr_No_Checks (L),
3245 Selector_Name => New_Reference_To (First_Tag_Component (T),
3248 -- Otherwise Tag_Tmp not used
3254 -- Processing for controlled types and types with controlled components
3256 -- Variables of such types contain pointers used to chain them in
3257 -- finalization lists, in addition to user data. These pointers are
3258 -- specific to each object of the type, not to the value being assigned.
3259 -- Thus they need to be left intact during the assignment. We achieve
3260 -- this by constructing a Storage_Array subtype, and by overlaying
3261 -- objects of this type on the source and target of the assignment.
3262 -- The assignment is then rewritten to assignments of slices of these
3263 -- arrays, copying the user data, and leaving the pointers untouched.
3266 Controlled_Actions : declare
3268 -- A reference to the Prev component of the record controller
3270 First_After_Root : Node_Id := Empty;
3271 -- Index of first byte to be copied (used to skip
3272 -- Root_Controlled in controlled objects).
3274 Last_Before_Hole : Node_Id := Empty;
3275 -- Index of last byte to be copied before outermost record
3278 Hole_Length : Node_Id := Empty;
3279 -- Length of record controller data (Prev and Next pointers)
3281 First_After_Hole : Node_Id := Empty;
3282 -- Index of first byte to be copied after outermost record
3285 Expr, Source_Size : Node_Id;
3286 Source_Actual_Subtype : Entity_Id;
3287 -- Used for computation of the size of the data to be copied
3289 Range_Type : Entity_Id;
3290 Opaque_Type : Entity_Id;
3292 function Build_Slice
3295 Hi : Node_Id) return Node_Id;
3296 -- Build and return a slice of an array of type S overlaid
3297 -- on object Rec, with bounds specified by Lo and Hi. If either
3298 -- bound is empty, a default of S'First (respectively S'Last)
3305 function Build_Slice
3308 Hi : Node_Id) return Node_Id
3313 Opaque : constant Node_Id :=
3314 Unchecked_Convert_To (Opaque_Type,
3315 Make_Attribute_Reference (Loc,
3317 Attribute_Name => Name_Address));
3318 -- Access value designating an opaque storage array of
3319 -- type S overlaid on record Rec.
3322 -- Compute slice bounds using S'First (1) and S'Last
3323 -- as default values when not specified by the caller.
3326 Lo_Bound := Make_Integer_Literal (Loc, 1);
3332 Hi_Bound := Make_Attribute_Reference (Loc,
3333 Prefix => New_Occurrence_Of (Range_Type, Loc),
3334 Attribute_Name => Name_Last);
3339 return Make_Slice (Loc,
3342 Discrete_Range => Make_Range (Loc,
3343 Lo_Bound, Hi_Bound));
3346 -- Start of processing for Controlled_Actions
3349 -- Create a constrained subtype of Storage_Array whose size
3350 -- corresponds to the value being assigned.
3352 -- subtype G is Storage_Offset range
3353 -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit
3355 Expr := Duplicate_Subexpr_No_Checks (Expression (N));
3357 if Nkind (Expr) = N_Qualified_Expression then
3358 Expr := Expression (Expr);
3361 Source_Actual_Subtype := Etype (Expr);
3363 if Has_Discriminants (Source_Actual_Subtype)
3364 and then not Is_Constrained (Source_Actual_Subtype)
3367 Build_Actual_Subtype (Source_Actual_Subtype, Expr));
3368 Source_Actual_Subtype := Defining_Identifier (Last (Res));
3374 Make_Attribute_Reference (Loc,
3376 New_Occurrence_Of (Source_Actual_Subtype, Loc),
3380 Make_Integer_Literal (Loc,
3381 System_Storage_Unit - 1));
3383 Make_Op_Divide (Loc,
3384 Left_Opnd => Source_Size,
3386 Make_Integer_Literal (Loc,
3387 Intval => System_Storage_Unit));
3390 Make_Defining_Identifier (Loc,
3391 New_Internal_Name ('G'));
3394 Make_Subtype_Declaration (Loc,
3395 Defining_Identifier => Range_Type,
3396 Subtype_Indication =>
3397 Make_Subtype_Indication (Loc,
3399 New_Reference_To (RTE (RE_Storage_Offset), Loc),
3400 Constraint => Make_Range_Constraint (Loc,
3403 Low_Bound => Make_Integer_Literal (Loc, 1),
3404 High_Bound => Source_Size)))));
3406 -- subtype S is Storage_Array (G)
3409 Make_Subtype_Declaration (Loc,
3410 Defining_Identifier =>
3411 Make_Defining_Identifier (Loc,
3412 New_Internal_Name ('S')),
3413 Subtype_Indication =>
3414 Make_Subtype_Indication (Loc,
3416 New_Reference_To (RTE (RE_Storage_Array), Loc),
3418 Make_Index_Or_Discriminant_Constraint (Loc,
3420 New_List (New_Reference_To (Range_Type, Loc))))));
3422 -- type A is access S
3425 Make_Defining_Identifier (Loc,
3426 Chars => New_Internal_Name ('A'));
3429 Make_Full_Type_Declaration (Loc,
3430 Defining_Identifier => Opaque_Type,
3432 Make_Access_To_Object_Definition (Loc,
3433 Subtype_Indication =>
3435 Defining_Identifier (Last (Res)), Loc))));
3437 -- Generate appropriate slice assignments
3439 First_After_Root := Make_Integer_Literal (Loc, 1);
3441 -- For the case of a controlled object, skip the
3442 -- Root_Controlled part.
3444 if Is_Controlled (T) then
3448 Make_Op_Divide (Loc,
3449 Make_Attribute_Reference (Loc,
3451 New_Occurrence_Of (RTE (RE_Root_Controlled), Loc),
3452 Attribute_Name => Name_Size),
3453 Make_Integer_Literal (Loc, System_Storage_Unit)));
3456 -- For the case of a record with controlled components, skip
3457 -- the Prev and Next components of the record controller.
3458 -- These components constitute a 'hole' in the middle of the
3459 -- data to be copied.
3461 if Has_Controlled_Component (T) then
3463 Make_Selected_Component (Loc,
3465 Make_Selected_Component (Loc,
3466 Prefix => Duplicate_Subexpr_No_Checks (L),
3468 New_Reference_To (Controller_Component (T), Loc)),
3469 Selector_Name => Make_Identifier (Loc, Name_Prev));
3471 -- Last index before hole: determined by position of
3472 -- the _Controller.Prev component.
3475 Make_Defining_Identifier (Loc,
3476 New_Internal_Name ('L'));
3479 Make_Object_Declaration (Loc,
3480 Defining_Identifier => Last_Before_Hole,
3481 Object_Definition => New_Occurrence_Of (
3482 RTE (RE_Storage_Offset), Loc),
3483 Constant_Present => True,
3484 Expression => Make_Op_Add (Loc,
3485 Make_Attribute_Reference (Loc,
3487 Attribute_Name => Name_Position),
3488 Make_Attribute_Reference (Loc,
3489 Prefix => New_Copy_Tree (Prefix (Prev_Ref)),
3490 Attribute_Name => Name_Position))));
3492 -- Hole length: size of the Prev and Next components
3495 Make_Op_Multiply (Loc,
3496 Left_Opnd => Make_Integer_Literal (Loc, Uint_2),
3498 Make_Op_Divide (Loc,
3500 Make_Attribute_Reference (Loc,
3501 Prefix => New_Copy_Tree (Prev_Ref),
3502 Attribute_Name => Name_Size),
3504 Make_Integer_Literal (Loc,
3505 Intval => System_Storage_Unit)));
3507 -- First index after hole
3510 Make_Defining_Identifier (Loc,
3511 New_Internal_Name ('F'));
3514 Make_Object_Declaration (Loc,
3515 Defining_Identifier => First_After_Hole,
3516 Object_Definition => New_Occurrence_Of (
3517 RTE (RE_Storage_Offset), Loc),
3518 Constant_Present => True,
3524 New_Occurrence_Of (Last_Before_Hole, Loc),
3525 Right_Opnd => Hole_Length),
3526 Right_Opnd => Make_Integer_Literal (Loc, 1))));
3528 Last_Before_Hole := New_Occurrence_Of (Last_Before_Hole, Loc);
3529 First_After_Hole := New_Occurrence_Of (First_After_Hole, Loc);
3532 -- Assign the first slice (possibly skipping Root_Controlled,
3533 -- up to the beginning of the record controller if present,
3534 -- up to the end of the object if not).
3536 Append_To (Res, Make_Assignment_Statement (Loc,
3537 Name => Build_Slice (
3538 Rec => Duplicate_Subexpr_No_Checks (L),
3539 Lo => First_After_Root,
3540 Hi => Last_Before_Hole),
3542 Expression => Build_Slice (
3543 Rec => Expression (N),
3544 Lo => First_After_Root,
3545 Hi => New_Copy_Tree (Last_Before_Hole))));
3547 if Present (First_After_Hole) then
3549 -- If a record controller is present, copy the second slice,
3550 -- from right after the _Controller.Next component up to the
3551 -- end of the object.
3553 Append_To (Res, Make_Assignment_Statement (Loc,
3554 Name => Build_Slice (
3555 Rec => Duplicate_Subexpr_No_Checks (L),
3556 Lo => First_After_Hole,
3558 Expression => Build_Slice (
3559 Rec => Duplicate_Subexpr_No_Checks (Expression (N)),
3560 Lo => New_Copy_Tree (First_After_Hole),
3563 end Controlled_Actions;
3566 Append_To (Res, Relocate_Node (N));
3573 Make_Assignment_Statement (Loc,
3575 Make_Selected_Component (Loc,
3576 Prefix => Duplicate_Subexpr_No_Checks (L),
3577 Selector_Name => New_Reference_To (First_Tag_Component (T),
3579 Expression => New_Reference_To (Tag_Tmp, Loc)));
3582 -- Adjust the target after the assignment when controlled (not in the
3583 -- init proc since it is an initialization more than an assignment).
3586 Append_List_To (Res,
3588 Ref => Duplicate_Subexpr_Move_Checks (L),
3590 Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc),
3591 With_Attach => Make_Integer_Literal (Loc, 0)));
3597 -- Could use comment here ???
3599 when RE_Not_Available =>
3601 end Make_Tag_Ctrl_Assignment;
3603 ------------------------------------
3604 -- Possible_Bit_Aligned_Component --
3605 ------------------------------------
3607 function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean is
3611 -- Case of indexed component
3613 when N_Indexed_Component =>
3615 P : constant Node_Id := Prefix (N);
3616 Ptyp : constant Entity_Id := Etype (P);
3619 -- If we know the component size and it is less than 64, then
3620 -- we are definitely OK. The back end always does assignment
3621 -- of misaligned small objects correctly.
3623 if Known_Static_Component_Size (Ptyp)
3624 and then Component_Size (Ptyp) <= 64
3628 -- Otherwise, we need to test the prefix, to see if we are
3629 -- indexing from a possibly unaligned component.
3632 return Possible_Bit_Aligned_Component (P);
3636 -- Case of selected component
3638 when N_Selected_Component =>
3640 P : constant Node_Id := Prefix (N);
3641 Comp : constant Entity_Id := Entity (Selector_Name (N));
3644 -- If there is no component clause, then we are in the clear
3645 -- since the back end will never misalign a large component
3646 -- unless it is forced to do so. In the clear means we need
3647 -- only the recursive test on the prefix.
3649 if Component_May_Be_Bit_Aligned (Comp) then
3652 return Possible_Bit_Aligned_Component (P);
3656 -- If we have neither a record nor array component, it means that
3657 -- we have fallen off the top testing prefixes recursively, and
3658 -- we now have a stand alone object, where we don't have a problem
3664 end Possible_Bit_Aligned_Component;