1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2003, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 with Atree; use Atree;
28 with Checks; use Checks;
29 with Einfo; use Einfo;
30 with Exp_Aggr; use Exp_Aggr;
31 with Exp_Ch7; use Exp_Ch7;
32 with Exp_Ch11; use Exp_Ch11;
33 with Exp_Dbug; use Exp_Dbug;
34 with Exp_Pakd; use Exp_Pakd;
35 with Exp_Util; use Exp_Util;
36 with Hostparm; use Hostparm;
37 with Nlists; use Nlists;
38 with Nmake; use Nmake;
40 with Restrict; use Restrict;
41 with Rtsfind; use Rtsfind;
42 with Sinfo; use Sinfo;
44 with Sem_Ch8; use Sem_Ch8;
45 with Sem_Ch13; use Sem_Ch13;
46 with Sem_Eval; use Sem_Eval;
47 with Sem_Res; use Sem_Res;
48 with Sem_Util; use Sem_Util;
49 with Snames; use Snames;
50 with Stand; use Stand;
51 with Stringt; use Stringt;
52 with Tbuild; use Tbuild;
53 with Ttypes; use Ttypes;
54 with Uintp; use Uintp;
55 with Validsw; use Validsw;
57 package body Exp_Ch5 is
59 function Change_Of_Representation (N : Node_Id) return Boolean;
60 -- Determine if the right hand side of the assignment N is a type
61 -- conversion which requires a change of representation. Called
62 -- only for the array and record cases.
64 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id);
65 -- N is an assignment which assigns an array value. This routine process
66 -- the various special cases and checks required for such assignments,
67 -- including change of representation. Rhs is normally simply the right
68 -- hand side of the assignment, except that if the right hand side is
69 -- a type conversion or a qualified expression, then the Rhs is the
70 -- actual expression inside any such type conversions or qualifications.
72 function Expand_Assign_Array_Loop
79 Rev : Boolean) return Node_Id;
80 -- N is an assignment statement which assigns an array value. This routine
81 -- expands the assignment into a loop (or nested loops for the case of a
82 -- multi-dimensional array) to do the assignment component by component.
83 -- Larray and Rarray are the entities of the actual arrays on the left
84 -- hand and right hand sides. L_Type and R_Type are the types of these
85 -- arrays (which may not be the same, due to either sliding, or to a
86 -- change of representation case). Ndim is the number of dimensions and
87 -- the parameter Rev indicates if the loops run normally (Rev = False),
88 -- or reversed (Rev = True). The value returned is the constructed
89 -- loop statement. Auxiliary declarations are inserted before node N
90 -- using the standard Insert_Actions mechanism.
92 procedure Expand_Assign_Record (N : Node_Id);
93 -- N is an assignment of a non-tagged record value. This routine handles
94 -- the case where the assignment must be made component by component,
95 -- either because the target is not byte aligned, or there is a change
98 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
99 -- Generate the necessary code for controlled and Tagged assignment,
100 -- that is to say, finalization of the target before, adjustement of
101 -- the target after and save and restore of the tag and finalization
102 -- pointers which are not 'part of the value' and must not be changed
103 -- upon assignment. N is the original Assignment node.
105 function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean;
106 -- This function is used in processing the assignment of a record or
107 -- indexed component. The argument N is either the left hand or right
108 -- hand side of an assignment, and this function determines if there
109 -- is a record component reference where the record may be bit aligned
110 -- in a manner that causes trouble for the back end (see description
111 -- of Sem_Util.Component_May_Be_Bit_Aligned for further details).
113 ------------------------------
114 -- Change_Of_Representation --
115 ------------------------------
117 function Change_Of_Representation (N : Node_Id) return Boolean is
118 Rhs : constant Node_Id := Expression (N);
121 Nkind (Rhs) = N_Type_Conversion
123 not Same_Representation (Etype (Rhs), Etype (Expression (Rhs)));
124 end Change_Of_Representation;
126 -------------------------
127 -- Expand_Assign_Array --
128 -------------------------
130 -- There are two issues here. First, do we let Gigi do a block move, or
131 -- do we expand out into a loop? Second, we need to set the two flags
132 -- Forwards_OK and Backwards_OK which show whether the block move (or
133 -- corresponding loops) can be legitimately done in a forwards (low to
134 -- high) or backwards (high to low) manner.
136 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is
137 Loc : constant Source_Ptr := Sloc (N);
139 Lhs : constant Node_Id := Name (N);
141 Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs);
142 Act_Rhs : Node_Id := Get_Referenced_Object (Rhs);
144 L_Type : constant Entity_Id :=
145 Underlying_Type (Get_Actual_Subtype (Act_Lhs));
146 R_Type : Entity_Id :=
147 Underlying_Type (Get_Actual_Subtype (Act_Rhs));
149 L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice;
150 R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice;
152 Crep : constant Boolean := Change_Of_Representation (N);
157 Ndim : constant Pos := Number_Dimensions (L_Type);
159 Loop_Required : Boolean := False;
160 -- This switch is set to True if the array move must be done using
161 -- an explicit front end generated loop.
163 function Has_Address_Clause (Exp : Node_Id) return Boolean;
164 -- Test if Exp is a reference to an array whose declaration has
165 -- an address clause, or it is a slice of such an array.
167 function Is_Formal_Array (Exp : Node_Id) return Boolean;
168 -- Test if Exp is a reference to an array which is either a formal
169 -- parameter or a slice of a formal parameter. These are the cases
170 -- where hidden aliasing can occur.
172 function Is_Non_Local_Array (Exp : Node_Id) return Boolean;
173 -- Determine if Exp is a reference to an array variable which is other
174 -- than an object defined in the current scope, or a slice of such
175 -- an object. Such objects can be aliased to parameters (unlike local
176 -- array references).
178 function Possible_Unaligned_Slice (Arg : Node_Id) return Boolean;
179 -- Returns True if Arg (either the left or right hand side of the
180 -- assignment) is a slice that could be unaligned wrt the array type.
181 -- This is true if Arg is a component of a packed record, or is
182 -- a record component to which a component clause applies. This
183 -- is a little pessimistic, but the result of an unnecessary
184 -- decision that something is possibly unaligned is only to
185 -- generate a front end loop, which is not so terrible.
186 -- It would really be better if backend handled this ???
188 ------------------------
189 -- Has_Address_Clause --
190 ------------------------
192 function Has_Address_Clause (Exp : Node_Id) return Boolean is
195 (Is_Entity_Name (Exp) and then
196 Present (Address_Clause (Entity (Exp))))
198 (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp)));
199 end Has_Address_Clause;
201 ---------------------
202 -- Is_Formal_Array --
203 ---------------------
205 function Is_Formal_Array (Exp : Node_Id) return Boolean is
208 (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp)))
210 (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp)));
213 ------------------------
214 -- Is_Non_Local_Array --
215 ------------------------
217 function Is_Non_Local_Array (Exp : Node_Id) return Boolean is
219 return (Is_Entity_Name (Exp)
220 and then Scope (Entity (Exp)) /= Current_Scope)
221 or else (Nkind (Exp) = N_Slice
222 and then Is_Non_Local_Array (Prefix (Exp)));
223 end Is_Non_Local_Array;
225 ------------------------------
226 -- Possible_Unaligned_Slice --
227 ------------------------------
229 function Possible_Unaligned_Slice (Arg : Node_Id) return Boolean is
231 -- No issue if this is not a slice, or else strict alignment
232 -- is not required in any case.
234 if Nkind (Arg) /= N_Slice
235 or else not Target_Strict_Alignment
240 -- No issue if the component type is a byte or byte aligned
243 Array_Typ : constant Entity_Id := Etype (Arg);
244 Comp_Typ : constant Entity_Id := Component_Type (Array_Typ);
245 Pref : constant Node_Id := Prefix (Arg);
248 if Known_Alignment (Array_Typ) then
249 if Alignment (Array_Typ) = 1 then
253 elsif Known_Component_Size (Array_Typ) then
254 if Component_Size (Array_Typ) = 1 then
258 elsif Known_Esize (Comp_Typ) then
259 if Esize (Comp_Typ) <= System_Storage_Unit then
264 -- No issue if this is not a selected component
266 if Nkind (Pref) /= N_Selected_Component then
270 -- Else we test for a possibly unaligned component
273 Is_Packed (Etype (Pref))
275 Present (Component_Clause (Entity (Selector_Name (Pref))));
277 end Possible_Unaligned_Slice;
279 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
281 Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs);
282 Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs);
284 Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs);
285 Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs);
287 -- Start of processing for Expand_Assign_Array
290 -- Deal with length check, note that the length check is done with
291 -- respect to the right hand side as given, not a possible underlying
292 -- renamed object, since this would generate incorrect extra checks.
294 Apply_Length_Check (Rhs, L_Type);
296 -- We start by assuming that the move can be done in either
297 -- direction, i.e. that the two sides are completely disjoint.
299 Set_Forwards_OK (N, True);
300 Set_Backwards_OK (N, True);
302 -- Normally it is only the slice case that can lead to overlap,
303 -- and explicit checks for slices are made below. But there is
304 -- one case where the slice can be implicit and invisible to us
305 -- and that is the case where we have a one dimensional array,
306 -- and either both operands are parameters, or one is a parameter
307 -- and the other is a global variable. In this case the parameter
308 -- could be a slice that overlaps with the other parameter.
310 -- Check for the case of slices requiring an explicit loop. Normally
311 -- it is only the explicit slice cases that bother us, but in the
312 -- case of one dimensional arrays, parameters can be slices that
313 -- are passed by reference, so we can have aliasing for assignments
314 -- from one parameter to another, or assignments between parameters
315 -- and nonlocal variables. However, if the array subtype is a
316 -- constrained first subtype in the parameter case, then we don't
317 -- have to worry about overlap, since slice assignments aren't
318 -- possible (other than for a slice denoting the whole array).
320 -- Note: overlap is never possible if there is a change of
321 -- representation, so we can exclude this case.
326 ((Lhs_Formal and Rhs_Formal)
328 (Lhs_Formal and Rhs_Non_Local_Var)
330 (Rhs_Formal and Lhs_Non_Local_Var))
332 (not Is_Constrained (Etype (Lhs))
333 or else not Is_First_Subtype (Etype (Lhs)))
335 -- In the case of compiling for the Java Virtual Machine,
336 -- slices are always passed by making a copy, so we don't
337 -- have to worry about overlap. We also want to prevent
338 -- generation of "<" comparisons for array addresses,
339 -- since that's a meaningless operation on the JVM.
343 Set_Forwards_OK (N, False);
344 Set_Backwards_OK (N, False);
346 -- Note: the bit-packed case is not worrisome here, since if
347 -- we have a slice passed as a parameter, it is always aligned
348 -- on a byte boundary, and if there are no explicit slices, the
349 -- assignment can be performed directly.
352 -- We certainly must use a loop for change of representation
353 -- and also we use the operand of the conversion on the right
354 -- hand side as the effective right hand side (the component
355 -- types must match in this situation).
358 Act_Rhs := Get_Referenced_Object (Rhs);
359 R_Type := Get_Actual_Subtype (Act_Rhs);
360 Loop_Required := True;
362 -- We require a loop if the left side is possibly bit unaligned
364 elsif Possible_Bit_Aligned_Component (Lhs)
366 Possible_Bit_Aligned_Component (Rhs)
368 Loop_Required := True;
370 -- Arrays with controlled components are expanded into a loop
371 -- to force calls to adjust at the component level.
373 elsif Has_Controlled_Component (L_Type) then
374 Loop_Required := True;
376 -- Case where no slice is involved
378 elsif not L_Slice and not R_Slice then
380 -- The following code deals with the case of unconstrained bit
381 -- packed arrays. The problem is that the template for such
382 -- arrays contains the bounds of the actual source level array,
384 -- But the copy of an entire array requires the bounds of the
385 -- underlying array. It would be nice if the back end could take
386 -- care of this, but right now it does not know how, so if we
387 -- have such a type, then we expand out into a loop, which is
388 -- inefficient but works correctly. If we don't do this, we
389 -- get the wrong length computed for the array to be moved.
390 -- The two cases we need to worry about are:
392 -- Explicit deference of an unconstrained packed array type as
393 -- in the following example:
396 -- type BITS is array(INTEGER range <>) of BOOLEAN;
397 -- pragma PACK(BITS);
398 -- type A is access BITS;
401 -- P1 := new BITS (1 .. 65_535);
402 -- P2 := new BITS (1 .. 65_535);
406 -- A formal parameter reference with an unconstrained bit
407 -- array type is the other case we need to worry about (here
408 -- we assume the same BITS type declared above:
410 -- procedure Write_All (File : out BITS; Contents : in BITS);
412 -- File.Storage := Contents;
415 -- We expand to a loop in either of these two cases.
417 -- Question for future thought. Another potentially more efficient
418 -- approach would be to create the actual subtype, and then do an
419 -- unchecked conversion to this actual subtype ???
421 Check_Unconstrained_Bit_Packed_Array : declare
423 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean;
424 -- Function to perform required test for the first case,
425 -- above (dereference of an unconstrained bit packed array)
427 -----------------------
428 -- Is_UBPA_Reference --
429 -----------------------
431 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is
432 Typ : constant Entity_Id := Underlying_Type (Etype (Opnd));
434 Des_Type : Entity_Id;
437 if Present (Packed_Array_Type (Typ))
438 and then Is_Array_Type (Packed_Array_Type (Typ))
439 and then not Is_Constrained (Packed_Array_Type (Typ))
443 elsif Nkind (Opnd) = N_Explicit_Dereference then
444 P_Type := Underlying_Type (Etype (Prefix (Opnd)));
446 if not Is_Access_Type (P_Type) then
450 Des_Type := Designated_Type (P_Type);
452 Is_Bit_Packed_Array (Des_Type)
453 and then not Is_Constrained (Des_Type);
459 end Is_UBPA_Reference;
461 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
464 if Is_UBPA_Reference (Lhs)
466 Is_UBPA_Reference (Rhs)
468 Loop_Required := True;
470 -- Here if we do not have the case of a reference to a bit
471 -- packed unconstrained array case. In this case gigi can
472 -- most certainly handle the assignment if a forwards move
475 -- (could it handle the backwards case also???)
477 elsif Forwards_OK (N) then
480 end Check_Unconstrained_Bit_Packed_Array;
482 -- Gigi can always handle the assignment if the right side is a string
483 -- literal (note that overlap is definitely impossible in this case).
484 -- If the type is packed, a string literal is always converted into a
485 -- aggregate, except in the case of a null slice, for which no aggregate
486 -- can be written. In that case, rewrite the assignment as a null
487 -- statement, a length check has already been emitted to verify that
488 -- the range of the left-hand side is empty.
490 -- Note that this code is not executed if we had an assignment of
491 -- a string literal to a non-bit aligned component of a record, a
492 -- case which cannot be handled by the backend
494 elsif Nkind (Rhs) = N_String_Literal then
495 if String_Length (Strval (Rhs)) = 0
496 and then Is_Bit_Packed_Array (L_Type)
498 Rewrite (N, Make_Null_Statement (Loc));
504 -- If either operand is bit packed, then we need a loop, since we
505 -- can't be sure that the slice is byte aligned. Similarly, if either
506 -- operand is a possibly unaligned slice, then we need a loop (since
507 -- gigi cannot handle unaligned slices).
509 elsif Is_Bit_Packed_Array (L_Type)
510 or else Is_Bit_Packed_Array (R_Type)
511 or else Possible_Unaligned_Slice (Lhs)
512 or else Possible_Unaligned_Slice (Rhs)
514 Loop_Required := True;
516 -- If we are not bit-packed, and we have only one slice, then no
517 -- overlap is possible except in the parameter case, so we can let
518 -- gigi handle things.
520 elsif not (L_Slice and R_Slice) then
521 if Forwards_OK (N) then
526 -- Come here to compelete the analysis
528 -- Loop_Required: Set to True if we know that a loop is required
529 -- regardless of overlap considerations.
531 -- Forwards_OK: Set to False if we already know that a forwards
532 -- move is not safe, else set to True.
534 -- Backwards_OK: Set to False if we already know that a backwards
535 -- move is not safe, else set to True
537 -- Our task at this stage is to complete the overlap analysis, which
538 -- can result in possibly setting Forwards_OK or Backwards_OK to
539 -- False, and then generating the final code, either by deciding
540 -- that it is OK after all to let Gigi handle it, or by generating
541 -- appropriate code in the front end.
544 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
545 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type));
547 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ);
548 Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ);
549 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ);
550 Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ);
552 Act_L_Array : Node_Id;
553 Act_R_Array : Node_Id;
559 Cresult : Compare_Result;
562 -- Get the expressions for the arrays. If we are dealing with a
563 -- private type, then convert to the underlying type. We can do
564 -- direct assignments to an array that is a private type, but
565 -- we cannot assign to elements of the array without this extra
566 -- unchecked conversion.
568 if Nkind (Act_Lhs) = N_Slice then
569 Larray := Prefix (Act_Lhs);
573 if Is_Private_Type (Etype (Larray)) then
576 (Underlying_Type (Etype (Larray)), Larray);
580 if Nkind (Act_Rhs) = N_Slice then
581 Rarray := Prefix (Act_Rhs);
585 if Is_Private_Type (Etype (Rarray)) then
588 (Underlying_Type (Etype (Rarray)), Rarray);
592 -- If both sides are slices, we must figure out whether
593 -- it is safe to do the move in one direction or the other
594 -- It is always safe if there is a change of representation
595 -- since obviously two arrays with different representations
596 -- cannot possibly overlap.
598 if (not Crep) and L_Slice and R_Slice then
599 Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
600 Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
602 -- If both left and right hand arrays are entity names, and
603 -- refer to different entities, then we know that the move
604 -- is safe (the two storage areas are completely disjoint).
606 if Is_Entity_Name (Act_L_Array)
607 and then Is_Entity_Name (Act_R_Array)
608 and then Entity (Act_L_Array) /= Entity (Act_R_Array)
612 -- Otherwise, we assume the worst, which is that the two
613 -- arrays are the same array. There is no need to check if
614 -- we know that is the case, because if we don't know it,
615 -- we still have to assume it!
617 -- Generally if the same array is involved, then we have
618 -- an overlapping case. We will have to really assume the
619 -- worst (i.e. set neither of the OK flags) unless we can
620 -- determine the lower or upper bounds at compile time and
624 Cresult := Compile_Time_Compare (Left_Lo, Right_Lo);
626 if Cresult = Unknown then
627 Cresult := Compile_Time_Compare (Left_Hi, Right_Hi);
631 when LT | LE | EQ => Set_Backwards_OK (N, False);
632 when GT | GE => Set_Forwards_OK (N, False);
633 when NE | Unknown => Set_Backwards_OK (N, False);
634 Set_Forwards_OK (N, False);
639 -- If after that analysis, Forwards_OK is still True, and
640 -- Loop_Required is False, meaning that we have not discovered
641 -- some non-overlap reason for requiring a loop, then we can
642 -- still let gigi handle it.
644 if not Loop_Required then
645 if Forwards_OK (N) then
650 -- Here is where a memmove would be appropriate ???
654 -- At this stage we have to generate an explicit loop, and
655 -- we have the following cases:
657 -- Forwards_OK = True
659 -- Rnn : right_index := right_index'First;
660 -- for Lnn in left-index loop
661 -- left (Lnn) := right (Rnn);
662 -- Rnn := right_index'Succ (Rnn);
665 -- Note: the above code MUST be analyzed with checks off,
666 -- because otherwise the Succ could overflow. But in any
667 -- case this is more efficient!
669 -- Forwards_OK = False, Backwards_OK = True
671 -- Rnn : right_index := right_index'Last;
672 -- for Lnn in reverse left-index loop
673 -- left (Lnn) := right (Rnn);
674 -- Rnn := right_index'Pred (Rnn);
677 -- Note: the above code MUST be analyzed with checks off,
678 -- because otherwise the Pred could overflow. But in any
679 -- case this is more efficient!
681 -- Forwards_OK = Backwards_OK = False
683 -- This only happens if we have the same array on each side. It is
684 -- possible to create situations using overlays that violate this,
685 -- but we simply do not promise to get this "right" in this case.
687 -- There are two possible subcases. If the No_Implicit_Conditionals
688 -- restriction is set, then we generate the following code:
691 -- T : constant <operand-type> := rhs;
696 -- If implicit conditionals are permitted, then we generate:
698 -- if Left_Lo <= Right_Lo then
699 -- <code for Forwards_OK = True above>
701 -- <code for Backwards_OK = True above>
704 -- Cases where either Forwards_OK or Backwards_OK is true
706 if Forwards_OK (N) or else Backwards_OK (N) then
708 Expand_Assign_Array_Loop
709 (N, Larray, Rarray, L_Type, R_Type, Ndim,
710 Rev => not Forwards_OK (N)));
712 -- Case of both are false with No_Implicit_Conditionals
714 elsif Restrictions (No_Implicit_Conditionals) then
716 T : constant Entity_Id :=
717 Make_Defining_Identifier (Loc, Chars => Name_T);
721 Make_Block_Statement (Loc,
722 Declarations => New_List (
723 Make_Object_Declaration (Loc,
724 Defining_Identifier => T,
725 Constant_Present => True,
727 New_Occurrence_Of (Etype (Rhs), Loc),
728 Expression => Relocate_Node (Rhs))),
730 Handled_Statement_Sequence =>
731 Make_Handled_Sequence_Of_Statements (Loc,
732 Statements => New_List (
733 Make_Assignment_Statement (Loc,
734 Name => Relocate_Node (Lhs),
735 Expression => New_Occurrence_Of (T, Loc))))));
738 -- Case of both are false with implicit conditionals allowed
741 -- Before we generate this code, we must ensure that the
742 -- left and right side array types are defined. They may
743 -- be itypes, and we cannot let them be defined inside the
744 -- if, since the first use in the then may not be executed.
746 Ensure_Defined (L_Type, N);
747 Ensure_Defined (R_Type, N);
749 -- We normally compare addresses to find out which way round
750 -- to do the loop, since this is realiable, and handles the
751 -- cases of parameters, conversions etc. But we can't do that
752 -- in the bit packed case or the Java VM case, because addresses
755 if not Is_Bit_Packed_Array (L_Type) and then not Java_VM then
759 Unchecked_Convert_To (RTE (RE_Integer_Address),
760 Make_Attribute_Reference (Loc,
762 Make_Indexed_Component (Loc,
764 Duplicate_Subexpr_Move_Checks (Larray, True),
765 Expressions => New_List (
766 Make_Attribute_Reference (Loc,
770 Attribute_Name => Name_First))),
771 Attribute_Name => Name_Address)),
774 Unchecked_Convert_To (RTE (RE_Integer_Address),
775 Make_Attribute_Reference (Loc,
777 Make_Indexed_Component (Loc,
779 Duplicate_Subexpr_Move_Checks (Rarray, True),
780 Expressions => New_List (
781 Make_Attribute_Reference (Loc,
785 Attribute_Name => Name_First))),
786 Attribute_Name => Name_Address)));
788 -- For the bit packed and Java VM cases we use the bounds.
789 -- That's OK, because we don't have to worry about parameters,
790 -- since they cannot cause overlap. Perhaps we should worry
791 -- about weird slice conversions ???
794 -- Copy the bounds and reset the Analyzed flag, because the
795 -- bounds of the index type itself may be universal, and must
796 -- must be reaanalyzed to acquire the proper type for Gigi.
798 Cleft_Lo := New_Copy_Tree (Left_Lo);
799 Cright_Lo := New_Copy_Tree (Right_Lo);
800 Set_Analyzed (Cleft_Lo, False);
801 Set_Analyzed (Cright_Lo, False);
805 Left_Opnd => Cleft_Lo,
806 Right_Opnd => Cright_Lo);
810 Make_Implicit_If_Statement (N,
811 Condition => Condition,
813 Then_Statements => New_List (
814 Expand_Assign_Array_Loop
815 (N, Larray, Rarray, L_Type, R_Type, Ndim,
818 Else_Statements => New_List (
819 Expand_Assign_Array_Loop
820 (N, Larray, Rarray, L_Type, R_Type, Ndim,
824 Analyze (N, Suppress => All_Checks);
828 when RE_Not_Available =>
830 end Expand_Assign_Array;
832 ------------------------------
833 -- Expand_Assign_Array_Loop --
834 ------------------------------
836 -- The following is an example of the loop generated for the case of
837 -- a two-dimensional array:
842 -- for L1b in 1 .. 100 loop
846 -- for L3b in 1 .. 100 loop
847 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
848 -- R4b := Tm1X2'succ(R4b);
851 -- R2b := Tm1X1'succ(R2b);
855 -- Here Rev is False, and Tm1Xn are the subscript types for the right
856 -- hand side. The declarations of R2b and R4b are inserted before the
857 -- original assignment statement.
859 function Expand_Assign_Array_Loop
866 Rev : Boolean) return Node_Id
868 Loc : constant Source_Ptr := Sloc (N);
870 Lnn : array (1 .. Ndim) of Entity_Id;
871 Rnn : array (1 .. Ndim) of Entity_Id;
872 -- Entities used as subscripts on left and right sides
874 L_Index_Type : array (1 .. Ndim) of Entity_Id;
875 R_Index_Type : array (1 .. Ndim) of Entity_Id;
876 -- Left and right index types
888 F_Or_L := Name_First;
892 -- Setup index types and subscript entities
899 L_Index := First_Index (L_Type);
900 R_Index := First_Index (R_Type);
902 for J in 1 .. Ndim loop
904 Make_Defining_Identifier (Loc,
905 Chars => New_Internal_Name ('L'));
908 Make_Defining_Identifier (Loc,
909 Chars => New_Internal_Name ('R'));
911 L_Index_Type (J) := Etype (L_Index);
912 R_Index_Type (J) := Etype (R_Index);
914 Next_Index (L_Index);
915 Next_Index (R_Index);
919 -- Now construct the assignment statement
922 ExprL : constant List_Id := New_List;
923 ExprR : constant List_Id := New_List;
926 for J in 1 .. Ndim loop
927 Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc));
928 Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc));
932 Make_Assignment_Statement (Loc,
934 Make_Indexed_Component (Loc,
935 Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
936 Expressions => ExprL),
938 Make_Indexed_Component (Loc,
939 Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
940 Expressions => ExprR));
942 -- Propagate the No_Ctrl_Actions flag to individual assignments
944 Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
947 -- Now construct the loop from the inside out, with the last subscript
948 -- varying most rapidly. Note that Assign is first the raw assignment
949 -- statement, and then subsequently the loop that wraps it up.
951 for J in reverse 1 .. Ndim loop
953 Make_Block_Statement (Loc,
954 Declarations => New_List (
955 Make_Object_Declaration (Loc,
956 Defining_Identifier => Rnn (J),
958 New_Occurrence_Of (R_Index_Type (J), Loc),
960 Make_Attribute_Reference (Loc,
961 Prefix => New_Occurrence_Of (R_Index_Type (J), Loc),
962 Attribute_Name => F_Or_L))),
964 Handled_Statement_Sequence =>
965 Make_Handled_Sequence_Of_Statements (Loc,
966 Statements => New_List (
967 Make_Implicit_Loop_Statement (N,
969 Make_Iteration_Scheme (Loc,
970 Loop_Parameter_Specification =>
971 Make_Loop_Parameter_Specification (Loc,
972 Defining_Identifier => Lnn (J),
973 Reverse_Present => Rev,
974 Discrete_Subtype_Definition =>
975 New_Reference_To (L_Index_Type (J), Loc))),
977 Statements => New_List (
980 Make_Assignment_Statement (Loc,
981 Name => New_Occurrence_Of (Rnn (J), Loc),
983 Make_Attribute_Reference (Loc,
985 New_Occurrence_Of (R_Index_Type (J), Loc),
986 Attribute_Name => S_Or_P,
987 Expressions => New_List (
988 New_Occurrence_Of (Rnn (J), Loc)))))))));
992 end Expand_Assign_Array_Loop;
994 --------------------------
995 -- Expand_Assign_Record --
996 --------------------------
998 -- The only processing required is in the change of representation
999 -- case, where we must expand the assignment to a series of field
1000 -- by field assignments.
1002 procedure Expand_Assign_Record (N : Node_Id) is
1003 Lhs : constant Node_Id := Name (N);
1004 Rhs : Node_Id := Expression (N);
1007 -- If change of representation, then extract the real right hand
1008 -- side from the type conversion, and proceed with component-wise
1009 -- assignment, since the two types are not the same as far as the
1010 -- back end is concerned.
1012 if Change_Of_Representation (N) then
1013 Rhs := Expression (Rhs);
1015 -- If this may be a case of a large bit aligned component, then
1016 -- proceed with component-wise assignment, to avoid possible
1017 -- clobbering of other components sharing bits in the first or
1018 -- last byte of the component to be assigned.
1020 elsif Possible_Bit_Aligned_Component (Lhs)
1022 Possible_Bit_Aligned_Component (Rhs)
1026 -- If neither condition met, then nothing special to do, the back end
1027 -- can handle assignment of the entire component as a single entity.
1033 -- At this stage we know that we must do a component wise assignment
1036 Loc : constant Source_Ptr := Sloc (N);
1037 R_Typ : constant Entity_Id := Base_Type (Etype (Rhs));
1038 L_Typ : constant Entity_Id := Base_Type (Etype (Lhs));
1039 Decl : constant Node_Id := Declaration_Node (R_Typ);
1043 function Find_Component
1045 Comp : Entity_Id) return Entity_Id;
1046 -- Find the component with the given name in the underlying record
1047 -- declaration for Typ. We need to use the actual entity because
1048 -- the type may be private and resolution by identifier alone would
1051 function Make_Component_List_Assign (CL : Node_Id) return List_Id;
1052 -- Returns a sequence of statements to assign the components that
1053 -- are referenced in the given component list.
1055 function Make_Field_Assign (C : Entity_Id) return Node_Id;
1056 -- Given C, the entity for a discriminant or component, build
1057 -- an assignment for the corresponding field values.
1059 function Make_Field_Assigns (CI : List_Id) return List_Id;
1060 -- Given CI, a component items list, construct series of statements
1061 -- for fieldwise assignment of the corresponding components.
1063 --------------------
1064 -- Find_Component --
1065 --------------------
1067 function Find_Component
1069 Comp : Entity_Id) return Entity_Id
1071 Utyp : constant Entity_Id := Underlying_Type (Typ);
1075 C := First_Entity (Utyp);
1077 while Present (C) loop
1078 if Chars (C) = Chars (Comp) then
1084 raise Program_Error;
1087 --------------------------------
1088 -- Make_Component_List_Assign --
1089 --------------------------------
1091 function Make_Component_List_Assign (CL : Node_Id) return List_Id is
1092 CI : constant List_Id := Component_Items (CL);
1093 VP : constant Node_Id := Variant_Part (CL);
1102 Result := Make_Field_Assigns (CI);
1104 if Present (VP) then
1106 V := First_Non_Pragma (Variants (VP));
1108 while Present (V) loop
1111 DC := First (Discrete_Choices (V));
1112 while Present (DC) loop
1113 Append_To (DCH, New_Copy_Tree (DC));
1118 Make_Case_Statement_Alternative (Loc,
1119 Discrete_Choices => DCH,
1121 Make_Component_List_Assign (Component_List (V))));
1122 Next_Non_Pragma (V);
1126 Make_Case_Statement (Loc,
1128 Make_Selected_Component (Loc,
1129 Prefix => Duplicate_Subexpr (Rhs),
1131 Make_Identifier (Loc, Chars (Name (VP)))),
1132 Alternatives => Alts));
1137 end Make_Component_List_Assign;
1139 -----------------------
1140 -- Make_Field_Assign --
1141 -----------------------
1143 function Make_Field_Assign (C : Entity_Id) return Node_Id is
1148 Make_Assignment_Statement (Loc,
1150 Make_Selected_Component (Loc,
1151 Prefix => Duplicate_Subexpr (Lhs),
1153 New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
1155 Make_Selected_Component (Loc,
1156 Prefix => Duplicate_Subexpr (Rhs),
1157 Selector_Name => New_Occurrence_Of (C, Loc)));
1159 -- Set Assignment_OK, so discriminants can be assigned
1161 Set_Assignment_OK (Name (A), True);
1163 end Make_Field_Assign;
1165 ------------------------
1166 -- Make_Field_Assigns --
1167 ------------------------
1169 function Make_Field_Assigns (CI : List_Id) return List_Id is
1177 while Present (Item) loop
1178 if Nkind (Item) = N_Component_Declaration then
1180 (Result, Make_Field_Assign (Defining_Identifier (Item)));
1187 end Make_Field_Assigns;
1189 -- Start of processing for Expand_Assign_Record
1192 -- Note that we use the base types for this processing. This results
1193 -- in some extra work in the constrained case, but the change of
1194 -- representation case is so unusual that it is not worth the effort.
1196 -- First copy the discriminants. This is done unconditionally. It
1197 -- is required in the unconstrained left side case, and also in the
1198 -- case where this assignment was constructed during the expansion
1199 -- of a type conversion (since initialization of discriminants is
1200 -- suppressed in this case). It is unnecessary but harmless in
1203 if Has_Discriminants (L_Typ) then
1204 F := First_Discriminant (R_Typ);
1205 while Present (F) loop
1206 Insert_Action (N, Make_Field_Assign (F));
1207 Next_Discriminant (F);
1211 -- We know the underlying type is a record, but its current view
1212 -- may be private. We must retrieve the usable record declaration.
1214 if Nkind (Decl) = N_Private_Type_Declaration
1215 and then Present (Full_View (R_Typ))
1217 RDef := Type_Definition (Declaration_Node (Full_View (R_Typ)));
1219 RDef := Type_Definition (Decl);
1222 if Nkind (RDef) = N_Record_Definition
1223 and then Present (Component_List (RDef))
1226 (N, Make_Component_List_Assign (Component_List (RDef)));
1228 Rewrite (N, Make_Null_Statement (Loc));
1232 end Expand_Assign_Record;
1234 -----------------------------------
1235 -- Expand_N_Assignment_Statement --
1236 -----------------------------------
1238 -- For array types, deal with slice assignments and setting the flags
1239 -- to indicate if it can be statically determined which direction the
1240 -- move should go in. Also deal with generating range/length checks.
1242 procedure Expand_N_Assignment_Statement (N : Node_Id) is
1243 Loc : constant Source_Ptr := Sloc (N);
1244 Lhs : constant Node_Id := Name (N);
1245 Rhs : constant Node_Id := Expression (N);
1246 Typ : constant Entity_Id := Underlying_Type (Etype (Lhs));
1250 -- First deal with generation of range check if required. For now
1251 -- we do this only for discrete types.
1253 if Do_Range_Check (Rhs)
1254 and then Is_Discrete_Type (Typ)
1256 Set_Do_Range_Check (Rhs, False);
1257 Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed);
1260 -- Check for a special case where a high level transformation is
1261 -- required. If we have either of:
1266 -- where P is a reference to a bit packed array, then we have to unwind
1267 -- the assignment. The exact meaning of being a reference to a bit
1268 -- packed array is as follows:
1270 -- An indexed component whose prefix is a bit packed array is a
1271 -- reference to a bit packed array.
1273 -- An indexed component or selected component whose prefix is a
1274 -- reference to a bit packed array is itself a reference ot a
1275 -- bit packed array.
1277 -- The required transformation is
1279 -- Tnn : prefix_type := P;
1280 -- Tnn.field := rhs;
1285 -- Tnn : prefix_type := P;
1286 -- Tnn (subscr) := rhs;
1289 -- Since P is going to be evaluated more than once, any subscripts
1290 -- in P must have their evaluation forced.
1292 if (Nkind (Lhs) = N_Indexed_Component
1294 Nkind (Lhs) = N_Selected_Component)
1295 and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs))
1298 BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs));
1299 BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr);
1300 Tnn : constant Entity_Id :=
1301 Make_Defining_Identifier (Loc,
1302 Chars => New_Internal_Name ('T'));
1305 -- Insert the post assignment first, because we want to copy
1306 -- the BPAR_Expr tree before it gets analyzed in the context
1307 -- of the pre assignment. Note that we do not analyze the
1308 -- post assignment yet (we cannot till we have completed the
1309 -- analysis of the pre assignment). As usual, the analysis
1310 -- of this post assignment will happen on its own when we
1311 -- "run into" it after finishing the current assignment.
1314 Make_Assignment_Statement (Loc,
1315 Name => New_Copy_Tree (BPAR_Expr),
1316 Expression => New_Occurrence_Of (Tnn, Loc)));
1318 -- At this stage BPAR_Expr is a reference to a bit packed
1319 -- array where the reference was not expanded in the original
1320 -- tree, since it was on the left side of an assignment. But
1321 -- in the pre-assignment statement (the object definition),
1322 -- BPAR_Expr will end up on the right hand side, and must be
1323 -- reexpanded. To achieve this, we reset the analyzed flag
1324 -- of all selected and indexed components down to the actual
1325 -- indexed component for the packed array.
1329 Set_Analyzed (Exp, False);
1331 if Nkind (Exp) = N_Selected_Component
1333 Nkind (Exp) = N_Indexed_Component
1335 Exp := Prefix (Exp);
1341 -- Now we can insert and analyze the pre-assignment.
1343 -- If the right-hand side requires a transient scope, it has
1344 -- already been placed on the stack. However, the declaration is
1345 -- inserted in the tree outside of this scope, and must reflect
1346 -- the proper scope for its variable. This awkward bit is forced
1347 -- by the stricter scope discipline imposed by GCC 2.97.
1350 Uses_Transient_Scope : constant Boolean :=
1351 Scope_Is_Transient and then N = Node_To_Be_Wrapped;
1354 if Uses_Transient_Scope then
1355 New_Scope (Scope (Current_Scope));
1358 Insert_Before_And_Analyze (N,
1359 Make_Object_Declaration (Loc,
1360 Defining_Identifier => Tnn,
1361 Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc),
1362 Expression => BPAR_Expr));
1364 if Uses_Transient_Scope then
1369 -- Now fix up the original assignment and continue processing
1371 Rewrite (Prefix (Lhs),
1372 New_Occurrence_Of (Tnn, Loc));
1374 -- We do not need to reanalyze that assignment, and we do not need
1375 -- to worry about references to the temporary, but we do need to
1376 -- make sure that the temporary is not marked as a true constant
1377 -- since we now have a generate assignment to it!
1379 Set_Is_True_Constant (Tnn, False);
1383 -- When we have the appropriate type of aggregate in the
1384 -- expression (it has been determined during analysis of the
1385 -- aggregate by setting the delay flag), let's perform in place
1386 -- assignment and thus avoid creating a temporay.
1388 if Is_Delayed_Aggregate (Rhs) then
1389 Convert_Aggr_In_Assignment (N);
1390 Rewrite (N, Make_Null_Statement (Loc));
1395 -- Apply discriminant check if required. If Lhs is an access type
1396 -- to a designated type with discriminants, we must always check.
1398 if Has_Discriminants (Etype (Lhs)) then
1400 -- Skip discriminant check if change of representation. Will be
1401 -- done when the change of representation is expanded out.
1403 if not Change_Of_Representation (N) then
1404 Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs);
1407 -- If the type is private without discriminants, and the full type
1408 -- has discriminants (necessarily with defaults) a check may still be
1409 -- necessary if the Lhs is aliased. The private determinants must be
1410 -- visible to build the discriminant constraints.
1412 -- Only an explicit dereference that comes from source indicates
1413 -- aliasing. Access to formals of protected operations and entries
1414 -- create dereferences but are not semantic aliasings.
1416 elsif Is_Private_Type (Etype (Lhs))
1417 and then Has_Discriminants (Typ)
1418 and then Nkind (Lhs) = N_Explicit_Dereference
1419 and then Comes_From_Source (Lhs)
1422 Lt : constant Entity_Id := Etype (Lhs);
1424 Set_Etype (Lhs, Typ);
1425 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1426 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1427 Set_Etype (Lhs, Lt);
1430 -- If the Lhs has a private type with unknown discriminants, it
1431 -- may have a full view with discriminants, but those are nameable
1432 -- only in the underlying type, so convert the Rhs to it before
1433 -- potential checking.
1435 elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs)))
1436 and then Has_Discriminants (Typ)
1438 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1439 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1441 -- In the access type case, we need the same discriminant check,
1442 -- and also range checks if we have an access to constrained array.
1444 elsif Is_Access_Type (Etype (Lhs))
1445 and then Is_Constrained (Designated_Type (Etype (Lhs)))
1447 if Has_Discriminants (Designated_Type (Etype (Lhs))) then
1449 -- Skip discriminant check if change of representation. Will be
1450 -- done when the change of representation is expanded out.
1452 if not Change_Of_Representation (N) then
1453 Apply_Discriminant_Check (Rhs, Etype (Lhs));
1456 elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then
1457 Apply_Range_Check (Rhs, Etype (Lhs));
1459 if Is_Constrained (Etype (Lhs)) then
1460 Apply_Length_Check (Rhs, Etype (Lhs));
1463 if Nkind (Rhs) = N_Allocator then
1465 Target_Typ : constant Entity_Id := Etype (Expression (Rhs));
1466 C_Es : Check_Result;
1473 Etype (Designated_Type (Etype (Lhs))));
1485 -- Apply range check for access type case
1487 elsif Is_Access_Type (Etype (Lhs))
1488 and then Nkind (Rhs) = N_Allocator
1489 and then Nkind (Expression (Rhs)) = N_Qualified_Expression
1491 Analyze_And_Resolve (Expression (Rhs));
1493 (Expression (Rhs), Designated_Type (Etype (Lhs)));
1496 -- If we are assigning an access type and the left side is an
1497 -- entity, then make sure that Is_Known_Non_Null properly
1498 -- reflects the state of the entity after the assignment
1500 if Is_Access_Type (Typ)
1501 and then Is_Entity_Name (Lhs)
1502 and then Known_Non_Null (Rhs)
1503 and then Safe_To_Capture_Value (N, Entity (Lhs))
1505 Set_Is_Known_Non_Null (Entity (Lhs), Known_Non_Null (Rhs));
1508 -- Case of assignment to a bit packed array element
1510 if Nkind (Lhs) = N_Indexed_Component
1511 and then Is_Bit_Packed_Array (Etype (Prefix (Lhs)))
1513 Expand_Bit_Packed_Element_Set (N);
1516 -- Case of tagged type assignment
1518 elsif Is_Tagged_Type (Typ)
1519 or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ))
1521 Tagged_Case : declare
1522 L : List_Id := No_List;
1523 Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N);
1526 -- In the controlled case, we need to make sure that function
1527 -- calls are evaluated before finalizing the target. In all
1528 -- cases, it makes the expansion easier if the side-effects
1529 -- are removed first.
1531 Remove_Side_Effects (Lhs);
1532 Remove_Side_Effects (Rhs);
1534 -- Avoid recursion in the mechanism
1538 -- If dispatching assignment, we need to dispatch to _assign
1540 if Is_Class_Wide_Type (Typ)
1542 -- If the type is tagged, we may as well use the predefined
1543 -- primitive assignment. This avoids inlining a lot of code
1544 -- and in the class-wide case, the assignment is replaced by
1545 -- a dispatch call to _assign. Note that this cannot be done
1546 -- when discriminant checks are locally suppressed (as in
1547 -- extension aggregate expansions) because otherwise the
1548 -- discriminant check will be performed within the _assign
1551 or else (Is_Tagged_Type (Typ)
1552 and then Chars (Current_Scope) /= Name_uAssign
1553 and then Expand_Ctrl_Actions
1554 and then not Discriminant_Checks_Suppressed (Empty))
1556 -- Fetch the primitive op _assign and proper type to call
1557 -- it. Because of possible conflits between private and
1558 -- full view the proper type is fetched directly from the
1559 -- operation profile.
1562 Op : constant Entity_Id :=
1563 Find_Prim_Op (Typ, Name_uAssign);
1564 F_Typ : Entity_Id := Etype (First_Formal (Op));
1567 -- If the assignment is dispatching, make sure to use the
1568 -- ??? where is rest of this comment ???
1570 if Is_Class_Wide_Type (Typ) then
1571 F_Typ := Class_Wide_Type (F_Typ);
1575 Make_Procedure_Call_Statement (Loc,
1576 Name => New_Reference_To (Op, Loc),
1577 Parameter_Associations => New_List (
1578 Unchecked_Convert_To (F_Typ, Duplicate_Subexpr (Lhs)),
1579 Unchecked_Convert_To (F_Typ,
1580 Duplicate_Subexpr (Rhs)))));
1584 L := Make_Tag_Ctrl_Assignment (N);
1586 -- We can't afford to have destructive Finalization Actions
1587 -- in the Self assignment case, so if the target and the
1588 -- source are not obviously different, code is generated to
1589 -- avoid the self assignment case
1591 -- if lhs'address /= rhs'address then
1592 -- <code for controlled and/or tagged assignment>
1595 if not Statically_Different (Lhs, Rhs)
1596 and then Expand_Ctrl_Actions
1599 Make_Implicit_If_Statement (N,
1603 Make_Attribute_Reference (Loc,
1604 Prefix => Duplicate_Subexpr (Lhs),
1605 Attribute_Name => Name_Address),
1608 Make_Attribute_Reference (Loc,
1609 Prefix => Duplicate_Subexpr (Rhs),
1610 Attribute_Name => Name_Address)),
1612 Then_Statements => L));
1615 -- We need to set up an exception handler for implementing
1616 -- 7.6.1 (18). The remaining adjustments are tackled by the
1617 -- implementation of adjust for record_controllers (see
1620 -- This is skipped if we have no finalization
1622 if Expand_Ctrl_Actions
1623 and then not Restrictions (No_Finalization)
1626 Make_Block_Statement (Loc,
1627 Handled_Statement_Sequence =>
1628 Make_Handled_Sequence_Of_Statements (Loc,
1630 Exception_Handlers => New_List (
1631 Make_Exception_Handler (Loc,
1632 Exception_Choices =>
1633 New_List (Make_Others_Choice (Loc)),
1634 Statements => New_List (
1635 Make_Raise_Program_Error (Loc,
1637 PE_Finalize_Raised_Exception)
1643 Make_Block_Statement (Loc,
1644 Handled_Statement_Sequence =>
1645 Make_Handled_Sequence_Of_Statements (Loc, Statements => L)));
1647 -- If no restrictions on aborts, protect the whole assignement
1648 -- for controlled objects as per 9.8(11)
1650 if Controlled_Type (Typ)
1651 and then Expand_Ctrl_Actions
1652 and then Abort_Allowed
1655 Blk : constant Entity_Id :=
1656 New_Internal_Entity (
1657 E_Block, Current_Scope, Sloc (N), 'B');
1660 Set_Scope (Blk, Current_Scope);
1661 Set_Etype (Blk, Standard_Void_Type);
1662 Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N)));
1664 Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer));
1665 Set_At_End_Proc (Handled_Statement_Sequence (N),
1666 New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc));
1667 Expand_At_End_Handler
1668 (Handled_Statement_Sequence (N), Blk);
1678 elsif Is_Array_Type (Typ) then
1680 Actual_Rhs : Node_Id := Rhs;
1683 while Nkind (Actual_Rhs) = N_Type_Conversion
1685 Nkind (Actual_Rhs) = N_Qualified_Expression
1687 Actual_Rhs := Expression (Actual_Rhs);
1690 Expand_Assign_Array (N, Actual_Rhs);
1696 elsif Is_Record_Type (Typ) then
1697 Expand_Assign_Record (N);
1700 -- Scalar types. This is where we perform the processing related
1701 -- to the requirements of (RM 13.9.1(9-11)) concerning the handling
1702 -- of invalid scalar values.
1704 elsif Is_Scalar_Type (Typ) then
1706 -- Case where right side is known valid
1708 if Expr_Known_Valid (Rhs) then
1710 -- Here the right side is valid, so it is fine. The case to
1711 -- deal with is when the left side is a local variable reference
1712 -- whose value is not currently known to be valid. If this is
1713 -- the case, and the assignment appears in an unconditional
1714 -- context, then we can mark the left side as now being valid.
1716 if Is_Local_Variable_Reference (Lhs)
1717 and then not Is_Known_Valid (Entity (Lhs))
1718 and then In_Unconditional_Context (N)
1720 Set_Is_Known_Valid (Entity (Lhs), True);
1723 -- Case where right side may be invalid in the sense of the RM
1724 -- reference above. The RM does not require that we check for
1725 -- the validity on an assignment, but it does require that the
1726 -- assignment of an invalid value not cause erroneous behavior.
1728 -- The general approach in GNAT is to use the Is_Known_Valid flag
1729 -- to avoid the need for validity checking on assignments. However
1730 -- in some cases, we have to do validity checking in order to make
1731 -- sure that the setting of this flag is correct.
1734 -- Validate right side if we are validating copies
1736 if Validity_Checks_On
1737 and then Validity_Check_Copies
1741 -- We can propagate this to the left side where appropriate
1743 if Is_Local_Variable_Reference (Lhs)
1744 and then not Is_Known_Valid (Entity (Lhs))
1745 and then In_Unconditional_Context (N)
1747 Set_Is_Known_Valid (Entity (Lhs), True);
1750 -- Otherwise check to see what should be done
1752 -- If left side is a local variable, then we just set its
1753 -- flag to indicate that its value may no longer be valid,
1754 -- since we are copying a potentially invalid value.
1756 elsif Is_Local_Variable_Reference (Lhs) then
1757 Set_Is_Known_Valid (Entity (Lhs), False);
1759 -- Check for case of a nonlocal variable on the left side
1760 -- which is currently known to be valid. In this case, we
1761 -- simply ensure that the right side is valid. We only play
1762 -- the game of copying validity status for local variables,
1763 -- since we are doing this statically, not by tracing the
1766 elsif Is_Entity_Name (Lhs)
1767 and then Is_Known_Valid (Entity (Lhs))
1769 -- Note that the Ensure_Valid call is ignored if the
1770 -- Validity_Checking mode is set to none so we do not
1771 -- need to worry about that case here.
1775 -- In all other cases, we can safely copy an invalid value
1776 -- without worrying about the status of the left side. Since
1777 -- it is not a variable reference it will not be considered
1778 -- as being known to be valid in any case.
1786 -- Defend against invalid subscripts on left side if we are in
1787 -- standard validity checking mode. No need to do this if we
1788 -- are checking all subscripts.
1790 if Validity_Checks_On
1791 and then Validity_Check_Default
1792 and then not Validity_Check_Subscripts
1794 Check_Valid_Lvalue_Subscripts (Lhs);
1798 when RE_Not_Available =>
1800 end Expand_N_Assignment_Statement;
1802 ------------------------------
1803 -- Expand_N_Block_Statement --
1804 ------------------------------
1806 -- Encode entity names defined in block statement
1808 procedure Expand_N_Block_Statement (N : Node_Id) is
1810 Qualify_Entity_Names (N);
1811 end Expand_N_Block_Statement;
1813 -----------------------------
1814 -- Expand_N_Case_Statement --
1815 -----------------------------
1817 procedure Expand_N_Case_Statement (N : Node_Id) is
1818 Loc : constant Source_Ptr := Sloc (N);
1819 Expr : constant Node_Id := Expression (N);
1827 -- Check for the situation where we know at compile time which
1828 -- branch will be taken
1830 if Compile_Time_Known_Value (Expr) then
1831 Alt := Find_Static_Alternative (N);
1833 -- Move the statements from this alternative after the case
1834 -- statement. They are already analyzed, so will be skipped
1837 Insert_List_After (N, Statements (Alt));
1839 -- That leaves the case statement as a shell. The alternative
1840 -- that will be executed is reset to a null list. So now we can
1841 -- kill the entire case statement.
1843 Kill_Dead_Code (Expression (N));
1844 Kill_Dead_Code (Alternatives (N));
1845 Rewrite (N, Make_Null_Statement (Loc));
1849 -- Here if the choice is not determined at compile time
1852 Last_Alt : constant Node_Id := Last (Alternatives (N));
1854 Others_Present : Boolean;
1855 Others_Node : Node_Id;
1857 Then_Stms : List_Id;
1858 Else_Stms : List_Id;
1861 if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then
1862 Others_Present := True;
1863 Others_Node := Last_Alt;
1865 Others_Present := False;
1868 -- First step is to worry about possible invalid argument. The RM
1869 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
1870 -- outside the base range), then Constraint_Error must be raised.
1872 -- Case of validity check required (validity checks are on, the
1873 -- expression is not known to be valid, and the case statement
1874 -- comes from source -- no need to validity check internally
1875 -- generated case statements).
1877 if Validity_Check_Default then
1878 Ensure_Valid (Expr);
1881 -- If there is only a single alternative, just replace it with
1882 -- the sequence of statements since obviously that is what is
1883 -- going to be executed in all cases.
1885 Len := List_Length (Alternatives (N));
1888 -- We still need to evaluate the expression if it has any
1891 Remove_Side_Effects (Expression (N));
1893 Insert_List_After (N, Statements (First (Alternatives (N))));
1895 -- That leaves the case statement as a shell. The alternative
1896 -- that will be executed is reset to a null list. So now we can
1897 -- kill the entire case statement.
1899 Kill_Dead_Code (Expression (N));
1900 Rewrite (N, Make_Null_Statement (Loc));
1904 -- An optimization. If there are only two alternatives, and only
1905 -- a single choice, then rewrite the whole case statement as an
1906 -- if statement, since this can result in susbequent optimizations.
1907 -- This helps not only with case statements in the source of a
1908 -- simple form, but also with generated code (discriminant check
1909 -- functions in particular)
1912 Chlist := Discrete_Choices (First (Alternatives (N)));
1914 if List_Length (Chlist) = 1 then
1915 Choice := First (Chlist);
1917 Then_Stms := Statements (First (Alternatives (N)));
1918 Else_Stms := Statements (Last (Alternatives (N)));
1920 -- For TRUE, generate "expression", not expression = true
1922 if Nkind (Choice) = N_Identifier
1923 and then Entity (Choice) = Standard_True
1925 Cond := Expression (N);
1927 -- For FALSE, generate "expression" and switch then/else
1929 elsif Nkind (Choice) = N_Identifier
1930 and then Entity (Choice) = Standard_False
1932 Cond := Expression (N);
1933 Else_Stms := Statements (First (Alternatives (N)));
1934 Then_Stms := Statements (Last (Alternatives (N)));
1936 -- For a range, generate "expression in range"
1938 elsif Nkind (Choice) = N_Range
1939 or else (Nkind (Choice) = N_Attribute_Reference
1940 and then Attribute_Name (Choice) = Name_Range)
1941 or else (Is_Entity_Name (Choice)
1942 and then Is_Type (Entity (Choice)))
1943 or else Nkind (Choice) = N_Subtype_Indication
1947 Left_Opnd => Expression (N),
1948 Right_Opnd => Relocate_Node (Choice));
1950 -- For any other subexpression "expression = value"
1955 Left_Opnd => Expression (N),
1956 Right_Opnd => Relocate_Node (Choice));
1959 -- Now rewrite the case as an IF
1962 Make_If_Statement (Loc,
1964 Then_Statements => Then_Stms,
1965 Else_Statements => Else_Stms));
1971 -- If the last alternative is not an Others choice, replace it
1972 -- with an N_Others_Choice. Note that we do not bother to call
1973 -- Analyze on the modified case statement, since it's only effect
1974 -- would be to compute the contents of the Others_Discrete_Choices
1975 -- which is not needed by the back end anyway.
1977 -- The reason we do this is that the back end always needs some
1978 -- default for a switch, so if we have not supplied one in the
1979 -- processing above for validity checking, then we need to
1982 if not Others_Present then
1983 Others_Node := Make_Others_Choice (Sloc (Last_Alt));
1984 Set_Others_Discrete_Choices
1985 (Others_Node, Discrete_Choices (Last_Alt));
1986 Set_Discrete_Choices (Last_Alt, New_List (Others_Node));
1989 end Expand_N_Case_Statement;
1991 -----------------------------
1992 -- Expand_N_Exit_Statement --
1993 -----------------------------
1995 -- The only processing required is to deal with a possible C/Fortran
1996 -- boolean value used as the condition for the exit statement.
1998 procedure Expand_N_Exit_Statement (N : Node_Id) is
2000 Adjust_Condition (Condition (N));
2001 end Expand_N_Exit_Statement;
2003 -----------------------------
2004 -- Expand_N_Goto_Statement --
2005 -----------------------------
2007 -- Add poll before goto if polling active
2009 procedure Expand_N_Goto_Statement (N : Node_Id) is
2011 Generate_Poll_Call (N);
2012 end Expand_N_Goto_Statement;
2014 ---------------------------
2015 -- Expand_N_If_Statement --
2016 ---------------------------
2018 -- First we deal with the case of C and Fortran convention boolean
2019 -- values, with zero/non-zero semantics.
2021 -- Second, we deal with the obvious rewriting for the cases where the
2022 -- condition of the IF is known at compile time to be True or False.
2024 -- Third, we remove elsif parts which have non-empty Condition_Actions
2025 -- and rewrite as independent if statements. For example:
2036 -- <<condition actions of y>>
2042 -- This rewriting is needed if at least one elsif part has a non-empty
2043 -- Condition_Actions list. We also do the same processing if there is
2044 -- a constant condition in an elsif part (in conjunction with the first
2045 -- processing step mentioned above, for the recursive call made to deal
2046 -- with the created inner if, this deals with properly optimizing the
2047 -- cases of constant elsif conditions).
2049 procedure Expand_N_If_Statement (N : Node_Id) is
2050 Loc : constant Source_Ptr := Sloc (N);
2056 Adjust_Condition (Condition (N));
2058 -- The following loop deals with constant conditions for the IF. We
2059 -- need a loop because as we eliminate False conditions, we grab the
2060 -- first elsif condition and use it as the primary condition.
2062 while Compile_Time_Known_Value (Condition (N)) loop
2064 -- If condition is True, we can simply rewrite the if statement
2065 -- now by replacing it by the series of then statements.
2067 if Is_True (Expr_Value (Condition (N))) then
2069 -- All the else parts can be killed
2071 Kill_Dead_Code (Elsif_Parts (N));
2072 Kill_Dead_Code (Else_Statements (N));
2074 Hed := Remove_Head (Then_Statements (N));
2075 Insert_List_After (N, Then_Statements (N));
2079 -- If condition is False, then we can delete the condition and
2080 -- the Then statements
2083 -- We do not delete the condition if constant condition
2084 -- warnings are enabled, since otherwise we end up deleting
2085 -- the desired warning. Of course the backend will get rid
2086 -- of this True/False test anyway, so nothing is lost here.
2088 if not Constant_Condition_Warnings then
2089 Kill_Dead_Code (Condition (N));
2092 Kill_Dead_Code (Then_Statements (N));
2094 -- If there are no elsif statements, then we simply replace
2095 -- the entire if statement by the sequence of else statements.
2097 if No (Elsif_Parts (N)) then
2099 if No (Else_Statements (N))
2100 or else Is_Empty_List (Else_Statements (N))
2103 Make_Null_Statement (Sloc (N)));
2106 Hed := Remove_Head (Else_Statements (N));
2107 Insert_List_After (N, Else_Statements (N));
2113 -- If there are elsif statements, the first of them becomes
2114 -- the if/then section of the rebuilt if statement This is
2115 -- the case where we loop to reprocess this copied condition.
2118 Hed := Remove_Head (Elsif_Parts (N));
2119 Insert_Actions (N, Condition_Actions (Hed));
2120 Set_Condition (N, Condition (Hed));
2121 Set_Then_Statements (N, Then_Statements (Hed));
2123 if Is_Empty_List (Elsif_Parts (N)) then
2124 Set_Elsif_Parts (N, No_List);
2130 -- Loop through elsif parts, dealing with constant conditions and
2131 -- possible expression actions that are present.
2133 if Present (Elsif_Parts (N)) then
2134 E := First (Elsif_Parts (N));
2135 while Present (E) loop
2136 Adjust_Condition (Condition (E));
2138 -- If there are condition actions, then we rewrite the if
2139 -- statement as indicated above. We also do the same rewrite
2140 -- if the condition is True or False. The further processing
2141 -- of this constant condition is then done by the recursive
2142 -- call to expand the newly created if statement
2144 if Present (Condition_Actions (E))
2145 or else Compile_Time_Known_Value (Condition (E))
2147 -- Note this is not an implicit if statement, since it is
2148 -- part of an explicit if statement in the source (or of an
2149 -- implicit if statement that has already been tested).
2152 Make_If_Statement (Sloc (E),
2153 Condition => Condition (E),
2154 Then_Statements => Then_Statements (E),
2155 Elsif_Parts => No_List,
2156 Else_Statements => Else_Statements (N));
2158 -- Elsif parts for new if come from remaining elsif's of parent
2160 while Present (Next (E)) loop
2161 if No (Elsif_Parts (New_If)) then
2162 Set_Elsif_Parts (New_If, New_List);
2165 Append (Remove_Next (E), Elsif_Parts (New_If));
2168 Set_Else_Statements (N, New_List (New_If));
2170 if Present (Condition_Actions (E)) then
2171 Insert_List_Before (New_If, Condition_Actions (E));
2176 if Is_Empty_List (Elsif_Parts (N)) then
2177 Set_Elsif_Parts (N, No_List);
2183 -- No special processing for that elsif part, move to next
2191 -- Some more optimizations applicable if we still have an IF statement
2193 if Nkind (N) /= N_If_Statement then
2197 -- Another optimization, special cases that can be simplified
2199 -- if expression then
2205 -- can be changed to:
2207 -- return expression;
2211 -- if expression then
2217 -- can be changed to:
2219 -- return not (expression);
2221 if Nkind (N) = N_If_Statement
2222 and then No (Elsif_Parts (N))
2223 and then Present (Else_Statements (N))
2224 and then List_Length (Then_Statements (N)) = 1
2225 and then List_Length (Else_Statements (N)) = 1
2228 Then_Stm : constant Node_Id := First (Then_Statements (N));
2229 Else_Stm : constant Node_Id := First (Else_Statements (N));
2232 if Nkind (Then_Stm) = N_Return_Statement
2234 Nkind (Else_Stm) = N_Return_Statement
2237 Then_Expr : constant Node_Id := Expression (Then_Stm);
2238 Else_Expr : constant Node_Id := Expression (Else_Stm);
2241 if Nkind (Then_Expr) = N_Identifier
2243 Nkind (Else_Expr) = N_Identifier
2245 if Entity (Then_Expr) = Standard_True
2246 and then Entity (Else_Expr) = Standard_False
2249 Make_Return_Statement (Loc,
2250 Expression => Relocate_Node (Condition (N))));
2254 elsif Entity (Then_Expr) = Standard_False
2255 and then Entity (Else_Expr) = Standard_True
2258 Make_Return_Statement (Loc,
2261 Right_Opnd => Relocate_Node (Condition (N)))));
2270 end Expand_N_If_Statement;
2272 -----------------------------
2273 -- Expand_N_Loop_Statement --
2274 -----------------------------
2276 -- 1. Deal with while condition for C/Fortran boolean
2277 -- 2. Deal with loops with a non-standard enumeration type range
2278 -- 3. Deal with while loops where Condition_Actions is set
2279 -- 4. Insert polling call if required
2281 procedure Expand_N_Loop_Statement (N : Node_Id) is
2282 Loc : constant Source_Ptr := Sloc (N);
2283 Isc : constant Node_Id := Iteration_Scheme (N);
2286 if Present (Isc) then
2287 Adjust_Condition (Condition (Isc));
2290 if Is_Non_Empty_List (Statements (N)) then
2291 Generate_Poll_Call (First (Statements (N)));
2298 -- Handle the case where we have a for loop with the range type being
2299 -- an enumeration type with non-standard representation. In this case
2302 -- for x in [reverse] a .. b loop
2308 -- for xP in [reverse] integer
2309 -- range etype'Pos (a) .. etype'Pos (b) loop
2311 -- x : constant etype := Pos_To_Rep (xP);
2317 if Present (Loop_Parameter_Specification (Isc)) then
2319 LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
2320 Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
2321 Ltype : constant Entity_Id := Etype (Loop_Id);
2322 Btype : constant Entity_Id := Base_Type (Ltype);
2327 if not Is_Enumeration_Type (Btype)
2328 or else No (Enum_Pos_To_Rep (Btype))
2334 Make_Defining_Identifier (Loc,
2335 Chars => New_External_Name (Chars (Loop_Id), 'P'));
2337 -- If the type has a contiguous representation, successive
2338 -- values can be generated as offsets from the first literal.
2340 if Has_Contiguous_Rep (Btype) then
2342 Unchecked_Convert_To (Btype,
2345 Make_Integer_Literal (Loc,
2346 Enumeration_Rep (First_Literal (Btype))),
2347 Right_Opnd => New_Reference_To (New_Id, Loc)));
2349 -- Use the constructed array Enum_Pos_To_Rep.
2352 Make_Indexed_Component (Loc,
2353 Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc),
2354 Expressions => New_List (New_Reference_To (New_Id, Loc)));
2358 Make_Loop_Statement (Loc,
2359 Identifier => Identifier (N),
2362 Make_Iteration_Scheme (Loc,
2363 Loop_Parameter_Specification =>
2364 Make_Loop_Parameter_Specification (Loc,
2365 Defining_Identifier => New_Id,
2366 Reverse_Present => Reverse_Present (LPS),
2368 Discrete_Subtype_Definition =>
2369 Make_Subtype_Indication (Loc,
2372 New_Reference_To (Standard_Natural, Loc),
2375 Make_Range_Constraint (Loc,
2380 Make_Attribute_Reference (Loc,
2382 New_Reference_To (Btype, Loc),
2384 Attribute_Name => Name_Pos,
2386 Expressions => New_List (
2388 (Type_Low_Bound (Ltype)))),
2391 Make_Attribute_Reference (Loc,
2393 New_Reference_To (Btype, Loc),
2395 Attribute_Name => Name_Pos,
2397 Expressions => New_List (
2399 (Type_High_Bound (Ltype))))))))),
2401 Statements => New_List (
2402 Make_Block_Statement (Loc,
2403 Declarations => New_List (
2404 Make_Object_Declaration (Loc,
2405 Defining_Identifier => Loop_Id,
2406 Constant_Present => True,
2407 Object_Definition => New_Reference_To (Ltype, Loc),
2408 Expression => Expr)),
2410 Handled_Statement_Sequence =>
2411 Make_Handled_Sequence_Of_Statements (Loc,
2412 Statements => Statements (N)))),
2414 End_Label => End_Label (N)));
2418 -- Second case, if we have a while loop with Condition_Actions set,
2419 -- then we change it into a plain loop:
2428 -- <<condition actions>>
2434 and then Present (Condition_Actions (Isc))
2441 Make_Exit_Statement (Sloc (Condition (Isc)),
2443 Make_Op_Not (Sloc (Condition (Isc)),
2444 Right_Opnd => Condition (Isc)));
2446 Prepend (ES, Statements (N));
2447 Insert_List_Before (ES, Condition_Actions (Isc));
2449 -- This is not an implicit loop, since it is generated in
2450 -- response to the loop statement being processed. If this
2451 -- is itself implicit, the restriction has already been
2452 -- checked. If not, it is an explicit loop.
2455 Make_Loop_Statement (Sloc (N),
2456 Identifier => Identifier (N),
2457 Statements => Statements (N),
2458 End_Label => End_Label (N)));
2463 end Expand_N_Loop_Statement;
2465 -------------------------------
2466 -- Expand_N_Return_Statement --
2467 -------------------------------
2469 procedure Expand_N_Return_Statement (N : Node_Id) is
2470 Loc : constant Source_Ptr := Sloc (N);
2471 Exp : constant Node_Id := Expression (N);
2475 Scope_Id : Entity_Id;
2479 Goto_Stat : Node_Id;
2482 Return_Type : Entity_Id;
2483 Result_Exp : Node_Id;
2484 Result_Id : Entity_Id;
2485 Result_Obj : Node_Id;
2488 -- Case where returned expression is present
2490 if Present (Exp) then
2492 -- Always normalize C/Fortran boolean result. This is not always
2493 -- necessary, but it seems a good idea to minimize the passing
2494 -- around of non-normalized values, and in any case this handles
2495 -- the processing of barrier functions for protected types, which
2496 -- turn the condition into a return statement.
2498 Exptyp := Etype (Exp);
2500 if Is_Boolean_Type (Exptyp)
2501 and then Nonzero_Is_True (Exptyp)
2503 Adjust_Condition (Exp);
2504 Adjust_Result_Type (Exp, Exptyp);
2507 -- Do validity check if enabled for returns
2509 if Validity_Checks_On
2510 and then Validity_Check_Returns
2516 -- Find relevant enclosing scope from which return is returning
2518 Cur_Idx := Scope_Stack.Last;
2520 Scope_Id := Scope_Stack.Table (Cur_Idx).Entity;
2522 if Ekind (Scope_Id) /= E_Block
2523 and then Ekind (Scope_Id) /= E_Loop
2528 Cur_Idx := Cur_Idx - 1;
2529 pragma Assert (Cur_Idx >= 0);
2534 Kind := Ekind (Scope_Id);
2536 -- If it is a return from procedures do no extra steps.
2538 if Kind = E_Procedure or else Kind = E_Generic_Procedure then
2542 pragma Assert (Is_Entry (Scope_Id));
2544 -- Look at the enclosing block to see whether the return is from
2545 -- an accept statement or an entry body.
2547 for J in reverse 0 .. Cur_Idx loop
2548 Scope_Id := Scope_Stack.Table (J).Entity;
2549 exit when Is_Concurrent_Type (Scope_Id);
2552 -- If it is a return from accept statement it should be expanded
2553 -- as a call to RTS Complete_Rendezvous and a goto to the end of
2556 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
2557 -- Expand_N_Accept_Alternative in exp_ch9.adb)
2559 if Is_Task_Type (Scope_Id) then
2561 Call := (Make_Procedure_Call_Statement (Loc,
2562 Name => New_Reference_To
2563 (RTE (RE_Complete_Rendezvous), Loc)));
2564 Insert_Before (N, Call);
2565 -- why not insert actions here???
2568 Acc_Stat := Parent (N);
2569 while Nkind (Acc_Stat) /= N_Accept_Statement loop
2570 Acc_Stat := Parent (Acc_Stat);
2573 Lab_Node := Last (Statements
2574 (Handled_Statement_Sequence (Acc_Stat)));
2576 Goto_Stat := Make_Goto_Statement (Loc,
2577 Name => New_Occurrence_Of
2578 (Entity (Identifier (Lab_Node)), Loc));
2580 Set_Analyzed (Goto_Stat);
2582 Rewrite (N, Goto_Stat);
2585 -- If it is a return from an entry body, put a Complete_Entry_Body
2586 -- call in front of the return.
2588 elsif Is_Protected_Type (Scope_Id) then
2591 Make_Procedure_Call_Statement (Loc,
2592 Name => New_Reference_To
2593 (RTE (RE_Complete_Entry_Body), Loc),
2594 Parameter_Associations => New_List
2595 (Make_Attribute_Reference (Loc,
2599 (Corresponding_Body (Parent (Scope_Id))),
2601 Attribute_Name => Name_Unchecked_Access)));
2603 Insert_Before (N, Call);
2612 Return_Type := Etype (Scope_Id);
2613 Utyp := Underlying_Type (Return_Type);
2615 -- Check the result expression of a scalar function against
2616 -- the subtype of the function by inserting a conversion.
2617 -- This conversion must eventually be performed for other
2618 -- classes of types, but for now it's only done for scalars.
2621 if Is_Scalar_Type (T) then
2622 Rewrite (Exp, Convert_To (Return_Type, Exp));
2626 -- Implement the rules of 6.5(8-10), which require a tag check in
2627 -- the case of a limited tagged return type, and tag reassignment
2628 -- for nonlimited tagged results. These actions are needed when
2629 -- the return type is a specific tagged type and the result
2630 -- expression is a conversion or a formal parameter, because in
2631 -- that case the tag of the expression might differ from the tag
2632 -- of the specific result type.
2634 if Is_Tagged_Type (Utyp)
2635 and then not Is_Class_Wide_Type (Utyp)
2636 and then (Nkind (Exp) = N_Type_Conversion
2637 or else Nkind (Exp) = N_Unchecked_Type_Conversion
2638 or else (Is_Entity_Name (Exp)
2639 and then Ekind (Entity (Exp)) in Formal_Kind))
2641 -- When the return type is limited, perform a check that the
2642 -- tag of the result is the same as the tag of the return type.
2644 if Is_Limited_Type (Return_Type) then
2646 Make_Raise_Constraint_Error (Loc,
2650 Make_Selected_Component (Loc,
2651 Prefix => Duplicate_Subexpr (Exp),
2653 New_Reference_To (Tag_Component (Utyp), Loc)),
2655 Unchecked_Convert_To (RTE (RE_Tag),
2657 (Access_Disp_Table (Base_Type (Utyp)), Loc))),
2658 Reason => CE_Tag_Check_Failed));
2660 -- If the result type is a specific nonlimited tagged type,
2661 -- then we have to ensure that the tag of the result is that
2662 -- of the result type. This is handled by making a copy of the
2663 -- expression in the case where it might have a different tag,
2664 -- namely when the expression is a conversion or a formal
2665 -- parameter. We create a new object of the result type and
2666 -- initialize it from the expression, which will implicitly
2667 -- force the tag to be set appropriately.
2671 Make_Defining_Identifier (Loc, New_Internal_Name ('R'));
2672 Result_Exp := New_Reference_To (Result_Id, Loc);
2675 Make_Object_Declaration (Loc,
2676 Defining_Identifier => Result_Id,
2677 Object_Definition => New_Reference_To (Return_Type, Loc),
2678 Constant_Present => True,
2679 Expression => Relocate_Node (Exp));
2681 Set_Assignment_OK (Result_Obj);
2682 Insert_Action (Exp, Result_Obj);
2684 Rewrite (Exp, Result_Exp);
2685 Analyze_And_Resolve (Exp, Return_Type);
2689 -- Deal with returning variable length objects and controlled types
2691 -- Nothing to do if we are returning by reference, or this is not
2692 -- a type that requires special processing (indicated by the fact
2693 -- that it requires a cleanup scope for the secondary stack case)
2695 if Is_Return_By_Reference_Type (T)
2696 or else not Requires_Transient_Scope (Return_Type)
2700 -- Case of secondary stack not used
2702 elsif Function_Returns_With_DSP (Scope_Id) then
2704 -- Here what we need to do is to always return by reference, since
2705 -- we will return with the stack pointer depressed. We may need to
2706 -- do a copy to a local temporary before doing this return.
2708 No_Secondary_Stack_Case : declare
2709 Local_Copy_Required : Boolean := False;
2710 -- Set to True if a local copy is required
2712 Copy_Ent : Entity_Id;
2713 -- Used for the target entity if a copy is required
2716 -- Declaration used to create copy if needed
2718 procedure Test_Copy_Required (Expr : Node_Id);
2719 -- Determines if Expr represents a return value for which a
2720 -- copy is required. More specifically, a copy is not required
2721 -- if Expr represents an object or component of an object that
2722 -- is either in the local subprogram frame, or is constant.
2723 -- If a copy is required, then Local_Copy_Required is set True.
2725 ------------------------
2726 -- Test_Copy_Required --
2727 ------------------------
2729 procedure Test_Copy_Required (Expr : Node_Id) is
2733 -- If component, test prefix (object containing component)
2735 if Nkind (Expr) = N_Indexed_Component
2737 Nkind (Expr) = N_Selected_Component
2739 Test_Copy_Required (Prefix (Expr));
2742 -- See if we have an entity name
2744 elsif Is_Entity_Name (Expr) then
2745 Ent := Entity (Expr);
2747 -- Constant entity is always OK, no copy required
2749 if Ekind (Ent) = E_Constant then
2752 -- No copy required for local variable
2754 elsif Ekind (Ent) = E_Variable
2755 and then Scope (Ent) = Current_Subprogram
2761 -- All other cases require a copy
2763 Local_Copy_Required := True;
2764 end Test_Copy_Required;
2766 -- Start of processing for No_Secondary_Stack_Case
2769 -- No copy needed if result is from a function call.
2770 -- In this case the result is already being returned by
2771 -- reference with the stack pointer depressed.
2773 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2774 -- the copy for array types if the constrained status of the
2775 -- target type is different from that of the expression.
2777 if Requires_Transient_Scope (T)
2779 (not Is_Array_Type (T)
2780 or else Is_Constrained (T) = Is_Constrained (Return_Type)
2781 or else Controlled_Type (T))
2782 and then Nkind (Exp) = N_Function_Call
2786 -- We always need a local copy for a controlled type, since
2787 -- we are required to finalize the local value before return.
2788 -- The copy will automatically include the required finalize.
2789 -- Moreover, gigi cannot make this copy, since we need special
2790 -- processing to ensure proper behavior for finalization.
2792 -- Note: the reason we are returning with a depressed stack
2793 -- pointer in the controlled case (even if the type involved
2794 -- is constrained) is that we must make a local copy to deal
2795 -- properly with the requirement that the local result be
2798 elsif Controlled_Type (Utyp) then
2800 Make_Defining_Identifier (Loc,
2801 Chars => New_Internal_Name ('R'));
2803 -- Build declaration to do the copy, and insert it, setting
2804 -- Assignment_OK, because we may be copying a limited type.
2805 -- In addition we set the special flag to inhibit finalize
2806 -- attachment if this is a controlled type (since this attach
2807 -- must be done by the caller, otherwise if we attach it here
2808 -- we will finalize the returned result prematurely).
2811 Make_Object_Declaration (Loc,
2812 Defining_Identifier => Copy_Ent,
2813 Object_Definition => New_Occurrence_Of (Return_Type, Loc),
2814 Expression => Relocate_Node (Exp));
2816 Set_Assignment_OK (Decl);
2817 Set_Delay_Finalize_Attach (Decl);
2818 Insert_Action (N, Decl);
2820 -- Now the actual return uses the copied value
2822 Rewrite (Exp, New_Occurrence_Of (Copy_Ent, Loc));
2823 Analyze_And_Resolve (Exp, Return_Type);
2825 -- Since we have made the copy, gigi does not have to, so
2826 -- we set the By_Ref flag to prevent another copy being made.
2830 -- Non-controlled cases
2833 Test_Copy_Required (Exp);
2835 -- If a local copy is required, then gigi will make the
2836 -- copy, otherwise, we can return the result directly,
2837 -- so set By_Ref to suppress the gigi copy.
2839 if not Local_Copy_Required then
2843 end No_Secondary_Stack_Case;
2845 -- Here if secondary stack is used
2848 -- Make sure that no surrounding block will reclaim the
2849 -- secondary-stack on which we are going to put the result.
2850 -- Not only may this introduce secondary stack leaks but worse,
2851 -- if the reclamation is done too early, then the result we are
2852 -- returning may get clobbered. See example in 7417-003.
2855 S : Entity_Id := Current_Scope;
2858 while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop
2859 Set_Sec_Stack_Needed_For_Return (S, True);
2860 S := Enclosing_Dynamic_Scope (S);
2864 -- Optimize the case where the result is a function call. In this
2865 -- case either the result is already on the secondary stack, or is
2866 -- already being returned with the stack pointer depressed and no
2867 -- further processing is required except to set the By_Ref flag to
2868 -- ensure that gigi does not attempt an extra unnecessary copy.
2869 -- (actually not just unnecessary but harmfully wrong in the case
2870 -- of a controlled type, where gigi does not know how to do a copy).
2871 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2872 -- the copy for array types if the constrained status of the
2873 -- target type is different from that of the expression.
2875 if Requires_Transient_Scope (T)
2877 (not Is_Array_Type (T)
2878 or else Is_Constrained (T) = Is_Constrained (Return_Type)
2879 or else Controlled_Type (T))
2880 and then Nkind (Exp) = N_Function_Call
2884 -- For controlled types, do the allocation on the sec-stack
2885 -- manually in order to call adjust at the right time
2886 -- type Anon1 is access Return_Type;
2887 -- for Anon1'Storage_pool use ss_pool;
2888 -- Anon2 : anon1 := new Return_Type'(expr);
2889 -- return Anon2.all;
2891 elsif Controlled_Type (Utyp) then
2893 Loc : constant Source_Ptr := Sloc (N);
2894 Temp : constant Entity_Id :=
2895 Make_Defining_Identifier (Loc,
2896 Chars => New_Internal_Name ('R'));
2897 Acc_Typ : constant Entity_Id :=
2898 Make_Defining_Identifier (Loc,
2899 Chars => New_Internal_Name ('A'));
2900 Alloc_Node : Node_Id;
2903 Set_Ekind (Acc_Typ, E_Access_Type);
2905 Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool));
2908 Make_Allocator (Loc,
2910 Make_Qualified_Expression (Loc,
2911 Subtype_Mark => New_Reference_To (Etype (Exp), Loc),
2912 Expression => Relocate_Node (Exp)));
2914 Insert_List_Before_And_Analyze (N, New_List (
2915 Make_Full_Type_Declaration (Loc,
2916 Defining_Identifier => Acc_Typ,
2918 Make_Access_To_Object_Definition (Loc,
2919 Subtype_Indication =>
2920 New_Reference_To (Return_Type, Loc))),
2922 Make_Object_Declaration (Loc,
2923 Defining_Identifier => Temp,
2924 Object_Definition => New_Reference_To (Acc_Typ, Loc),
2925 Expression => Alloc_Node)));
2928 Make_Explicit_Dereference (Loc,
2929 Prefix => New_Reference_To (Temp, Loc)));
2931 Analyze_And_Resolve (Exp, Return_Type);
2934 -- Otherwise use the gigi mechanism to allocate result on the
2938 Set_Storage_Pool (N, RTE (RE_SS_Pool));
2940 -- If we are generating code for the Java VM do not use
2941 -- SS_Allocate since everything is heap-allocated anyway.
2944 Set_Procedure_To_Call (N, RTE (RE_SS_Allocate));
2950 when RE_Not_Available =>
2952 end Expand_N_Return_Statement;
2954 ------------------------------
2955 -- Make_Tag_Ctrl_Assignment --
2956 ------------------------------
2958 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is
2959 Loc : constant Source_Ptr := Sloc (N);
2960 L : constant Node_Id := Name (N);
2961 T : constant Entity_Id := Underlying_Type (Etype (L));
2963 Ctrl_Act : constant Boolean := Controlled_Type (T)
2964 and then not No_Ctrl_Actions (N);
2966 Save_Tag : constant Boolean := Is_Tagged_Type (T)
2967 and then not No_Ctrl_Actions (N)
2968 and then not Java_VM;
2969 -- Tags are not saved and restored when Java_VM because JVM tags
2970 -- are represented implicitly in objects.
2973 Tag_Tmp : Entity_Id;
2974 Prev_Tmp : Entity_Id;
2975 Next_Tmp : Entity_Id;
2977 Ctrl_Ref2 : Node_Id := Empty;
2978 Prev_Tmp2 : Entity_Id := Empty; -- prevent warning
2979 Next_Tmp2 : Entity_Id := Empty; -- prevent warning
2984 -- Finalize the target of the assignment when controlled.
2985 -- We have two exceptions here:
2987 -- 1. If we are in an init proc since it is an initialization
2988 -- more than an assignment
2990 -- 2. If the left-hand side is a temporary that was not initialized
2991 -- (or the parent part of a temporary since it is the case in
2992 -- extension aggregates). Such a temporary does not come from
2993 -- source. We must examine the original node for the prefix, because
2994 -- it may be a component of an entry formal, in which case it has
2995 -- been rewritten and does not appear to come from source either.
2997 -- Case of init proc
2999 if not Ctrl_Act then
3002 -- The left hand side is an uninitialized temporary
3004 elsif Nkind (L) = N_Type_Conversion
3005 and then Is_Entity_Name (Expression (L))
3006 and then No_Initialization (Parent (Entity (Expression (L))))
3010 Append_List_To (Res,
3012 Ref => Duplicate_Subexpr_No_Checks (L),
3014 With_Detach => New_Reference_To (Standard_False, Loc)));
3017 Next_Tmp := Make_Defining_Identifier (Loc, New_Internal_Name ('C'));
3019 -- Save the Tag in a local variable Tag_Tmp
3023 Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
3026 Make_Object_Declaration (Loc,
3027 Defining_Identifier => Tag_Tmp,
3028 Object_Definition => New_Reference_To (RTE (RE_Tag), Loc),
3030 Make_Selected_Component (Loc,
3031 Prefix => Duplicate_Subexpr_No_Checks (L),
3032 Selector_Name => New_Reference_To (Tag_Component (T), Loc))));
3034 -- Otherwise Tag_Tmp not used
3040 -- Save the Finalization Pointers in local variables Prev_Tmp and
3041 -- Next_Tmp. For objects with Has_Controlled_Component set, these
3042 -- pointers are in the Record_Controller and if it is also
3043 -- Is_Controlled, we need to save the object pointers as well.
3046 Ctrl_Ref := Duplicate_Subexpr_No_Checks (L);
3048 if Has_Controlled_Component (T) then
3050 Make_Selected_Component (Loc,
3053 New_Reference_To (Controller_Component (T), Loc));
3055 if Is_Controlled (T) then
3056 Ctrl_Ref2 := Duplicate_Subexpr_No_Checks (L);
3060 Prev_Tmp := Make_Defining_Identifier (Loc, New_Internal_Name ('B'));
3063 Make_Object_Declaration (Loc,
3064 Defining_Identifier => Prev_Tmp,
3066 Object_Definition =>
3067 New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
3070 Make_Selected_Component (Loc,
3072 Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref),
3073 Selector_Name => Make_Identifier (Loc, Name_Prev))));
3075 Next_Tmp := Make_Defining_Identifier (Loc, New_Internal_Name ('C'));
3078 Make_Object_Declaration (Loc,
3079 Defining_Identifier => Next_Tmp,
3081 Object_Definition =>
3082 New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
3085 Make_Selected_Component (Loc,
3087 Unchecked_Convert_To (RTE (RE_Finalizable),
3088 New_Copy_Tree (Ctrl_Ref)),
3089 Selector_Name => Make_Identifier (Loc, Name_Next))));
3091 if Present (Ctrl_Ref2) then
3093 Make_Defining_Identifier (Loc, New_Internal_Name ('B'));
3096 Make_Object_Declaration (Loc,
3097 Defining_Identifier => Prev_Tmp2,
3099 Object_Definition =>
3100 New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
3103 Make_Selected_Component (Loc,
3105 Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref2),
3106 Selector_Name => Make_Identifier (Loc, Name_Prev))));
3109 Make_Defining_Identifier (Loc, New_Internal_Name ('C'));
3112 Make_Object_Declaration (Loc,
3113 Defining_Identifier => Next_Tmp2,
3115 Object_Definition =>
3116 New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
3119 Make_Selected_Component (Loc,
3121 Unchecked_Convert_To (RTE (RE_Finalizable),
3122 New_Copy_Tree (Ctrl_Ref2)),
3123 Selector_Name => Make_Identifier (Loc, Name_Next))));
3126 -- If not controlled type, then Prev_Tmp and Ctrl_Ref unused
3133 -- Do the Assignment
3135 Append_To (Res, Relocate_Node (N));
3141 Make_Assignment_Statement (Loc,
3143 Make_Selected_Component (Loc,
3144 Prefix => Duplicate_Subexpr_No_Checks (L),
3145 Selector_Name => New_Reference_To (Tag_Component (T), Loc)),
3146 Expression => New_Reference_To (Tag_Tmp, Loc)));
3149 -- Restore the finalization pointers
3153 Make_Assignment_Statement (Loc,
3155 Make_Selected_Component (Loc,
3157 Unchecked_Convert_To (RTE (RE_Finalizable),
3158 New_Copy_Tree (Ctrl_Ref)),
3159 Selector_Name => Make_Identifier (Loc, Name_Prev)),
3160 Expression => New_Reference_To (Prev_Tmp, Loc)));
3163 Make_Assignment_Statement (Loc,
3165 Make_Selected_Component (Loc,
3167 Unchecked_Convert_To (RTE (RE_Finalizable),
3168 New_Copy_Tree (Ctrl_Ref)),
3169 Selector_Name => Make_Identifier (Loc, Name_Next)),
3170 Expression => New_Reference_To (Next_Tmp, Loc)));
3172 if Present (Ctrl_Ref2) then
3174 Make_Assignment_Statement (Loc,
3176 Make_Selected_Component (Loc,
3178 Unchecked_Convert_To (RTE (RE_Finalizable),
3179 New_Copy_Tree (Ctrl_Ref2)),
3180 Selector_Name => Make_Identifier (Loc, Name_Prev)),
3181 Expression => New_Reference_To (Prev_Tmp2, Loc)));
3184 Make_Assignment_Statement (Loc,
3186 Make_Selected_Component (Loc,
3188 Unchecked_Convert_To (RTE (RE_Finalizable),
3189 New_Copy_Tree (Ctrl_Ref2)),
3190 Selector_Name => Make_Identifier (Loc, Name_Next)),
3191 Expression => New_Reference_To (Next_Tmp2, Loc)));
3195 -- Adjust the target after the assignment when controlled. (not in
3196 -- the init proc since it is an initialization more than an
3200 Append_List_To (Res,
3202 Ref => Duplicate_Subexpr_Move_Checks (L),
3204 Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc),
3205 With_Attach => Make_Integer_Literal (Loc, 0)));
3211 when RE_Not_Available =>
3213 end Make_Tag_Ctrl_Assignment;
3215 ------------------------------------
3216 -- Possible_Bit_Aligned_Component --
3217 ------------------------------------
3219 function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean is
3223 -- Case of indexed component
3225 when N_Indexed_Component =>
3227 P : constant Node_Id := Prefix (N);
3228 Ptyp : constant Entity_Id := Etype (P);
3231 -- If we know the component size and it is less than 64, then
3232 -- we are definitely OK. The back end always does assignment
3233 -- of misaligned small objects correctly.
3235 if Known_Static_Component_Size (Ptyp)
3236 and then Component_Size (Ptyp) <= 64
3240 -- Otherwise, we need to test the prefix, to see if we are
3241 -- indexing from a possibly unaligned component.
3244 return Possible_Bit_Aligned_Component (P);
3248 -- Case of selected component
3250 when N_Selected_Component =>
3252 P : constant Node_Id := Prefix (N);
3253 Comp : constant Entity_Id := Entity (Selector_Name (N));
3256 -- If there is no component clause, then we are in the clear
3257 -- since the back end will never misalign a large component
3258 -- unless it is forced to do so. In the clear means we need
3259 -- only the recursive test on the prefix.
3261 if Component_May_Be_Bit_Aligned (Comp) then
3264 return Possible_Bit_Aligned_Component (P);
3268 -- If we have neither a record nor array component, it means that
3269 -- we have fallen off the top testing prefixes recursively, and
3270 -- we now have a stand alone object, where we don't have a problem
3276 end Possible_Bit_Aligned_Component;