1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2004, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 with Atree; use Atree;
28 with Checks; use Checks;
29 with Einfo; use Einfo;
30 with Exp_Aggr; use Exp_Aggr;
31 with Exp_Ch7; use Exp_Ch7;
32 with Exp_Ch11; use Exp_Ch11;
33 with Exp_Dbug; use Exp_Dbug;
34 with Exp_Pakd; use Exp_Pakd;
35 with Exp_Tss; use Exp_Tss;
36 with Exp_Util; use Exp_Util;
37 with Hostparm; use Hostparm;
38 with Nlists; use Nlists;
39 with Nmake; use Nmake;
41 with Restrict; use Restrict;
42 with Rident; use Rident;
43 with Rtsfind; use Rtsfind;
44 with Sinfo; use Sinfo;
46 with Sem_Ch8; use Sem_Ch8;
47 with Sem_Ch13; use Sem_Ch13;
48 with Sem_Eval; use Sem_Eval;
49 with Sem_Res; use Sem_Res;
50 with Sem_Util; use Sem_Util;
51 with Snames; use Snames;
52 with Stand; use Stand;
53 with Stringt; use Stringt;
54 with Tbuild; use Tbuild;
55 with Ttypes; use Ttypes;
56 with Uintp; use Uintp;
57 with Validsw; use Validsw;
59 package body Exp_Ch5 is
61 function Change_Of_Representation (N : Node_Id) return Boolean;
62 -- Determine if the right hand side of the assignment N is a type
63 -- conversion which requires a change of representation. Called
64 -- only for the array and record cases.
66 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id);
67 -- N is an assignment which assigns an array value. This routine process
68 -- the various special cases and checks required for such assignments,
69 -- including change of representation. Rhs is normally simply the right
70 -- hand side of the assignment, except that if the right hand side is
71 -- a type conversion or a qualified expression, then the Rhs is the
72 -- actual expression inside any such type conversions or qualifications.
74 function Expand_Assign_Array_Loop
81 Rev : Boolean) return Node_Id;
82 -- N is an assignment statement which assigns an array value. This routine
83 -- expands the assignment into a loop (or nested loops for the case of a
84 -- multi-dimensional array) to do the assignment component by component.
85 -- Larray and Rarray are the entities of the actual arrays on the left
86 -- hand and right hand sides. L_Type and R_Type are the types of these
87 -- arrays (which may not be the same, due to either sliding, or to a
88 -- change of representation case). Ndim is the number of dimensions and
89 -- the parameter Rev indicates if the loops run normally (Rev = False),
90 -- or reversed (Rev = True). The value returned is the constructed
91 -- loop statement. Auxiliary declarations are inserted before node N
92 -- using the standard Insert_Actions mechanism.
94 procedure Expand_Assign_Record (N : Node_Id);
95 -- N is an assignment of a non-tagged record value. This routine handles
96 -- the case where the assignment must be made component by component,
97 -- either because the target is not byte aligned, or there is a change
100 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
101 -- Generate the necessary code for controlled and tagged assignment,
102 -- that is to say, finalization of the target before, adjustement of
103 -- the target after and save and restore of the tag and finalization
104 -- pointers which are not 'part of the value' and must not be changed
105 -- upon assignment. N is the original Assignment node.
107 function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean;
108 -- This function is used in processing the assignment of a record or
109 -- indexed component. The argument N is either the left hand or right
110 -- hand side of an assignment, and this function determines if there
111 -- is a record component reference where the record may be bit aligned
112 -- in a manner that causes trouble for the back end (see description
113 -- of Exp_Util.Component_May_Be_Bit_Aligned for further details).
115 ------------------------------
116 -- Change_Of_Representation --
117 ------------------------------
119 function Change_Of_Representation (N : Node_Id) return Boolean is
120 Rhs : constant Node_Id := Expression (N);
123 Nkind (Rhs) = N_Type_Conversion
125 not Same_Representation (Etype (Rhs), Etype (Expression (Rhs)));
126 end Change_Of_Representation;
128 -------------------------
129 -- Expand_Assign_Array --
130 -------------------------
132 -- There are two issues here. First, do we let Gigi do a block move, or
133 -- do we expand out into a loop? Second, we need to set the two flags
134 -- Forwards_OK and Backwards_OK which show whether the block move (or
135 -- corresponding loops) can be legitimately done in a forwards (low to
136 -- high) or backwards (high to low) manner.
138 procedure Expand_Assign_Array (N : Node_Id; Rhs : Node_Id) is
139 Loc : constant Source_Ptr := Sloc (N);
141 Lhs : constant Node_Id := Name (N);
143 Act_Lhs : constant Node_Id := Get_Referenced_Object (Lhs);
144 Act_Rhs : Node_Id := Get_Referenced_Object (Rhs);
146 L_Type : constant Entity_Id :=
147 Underlying_Type (Get_Actual_Subtype (Act_Lhs));
148 R_Type : Entity_Id :=
149 Underlying_Type (Get_Actual_Subtype (Act_Rhs));
151 L_Slice : constant Boolean := Nkind (Act_Lhs) = N_Slice;
152 R_Slice : constant Boolean := Nkind (Act_Rhs) = N_Slice;
154 Crep : constant Boolean := Change_Of_Representation (N);
159 Ndim : constant Pos := Number_Dimensions (L_Type);
161 Loop_Required : Boolean := False;
162 -- This switch is set to True if the array move must be done using
163 -- an explicit front end generated loop.
165 procedure Apply_Dereference (Arg : in out Node_Id);
166 -- If the argument is an access to an array, and the assignment is
167 -- converted into a procedure call, apply explicit dereference.
169 function Has_Address_Clause (Exp : Node_Id) return Boolean;
170 -- Test if Exp is a reference to an array whose declaration has
171 -- an address clause, or it is a slice of such an array.
173 function Is_Formal_Array (Exp : Node_Id) return Boolean;
174 -- Test if Exp is a reference to an array which is either a formal
175 -- parameter or a slice of a formal parameter. These are the cases
176 -- where hidden aliasing can occur.
178 function Is_Non_Local_Array (Exp : Node_Id) return Boolean;
179 -- Determine if Exp is a reference to an array variable which is other
180 -- than an object defined in the current scope, or a slice of such
181 -- an object. Such objects can be aliased to parameters (unlike local
182 -- array references).
184 -----------------------
185 -- Apply_Dereference --
186 -----------------------
188 procedure Apply_Dereference (Arg : in out Node_Id) is
189 Typ : constant Entity_Id := Etype (Arg);
191 if Is_Access_Type (Typ) then
192 Rewrite (Arg, Make_Explicit_Dereference (Loc,
193 Prefix => Relocate_Node (Arg)));
194 Analyze_And_Resolve (Arg, Designated_Type (Typ));
196 end Apply_Dereference;
198 ------------------------
199 -- Has_Address_Clause --
200 ------------------------
202 function Has_Address_Clause (Exp : Node_Id) return Boolean is
205 (Is_Entity_Name (Exp) and then
206 Present (Address_Clause (Entity (Exp))))
208 (Nkind (Exp) = N_Slice and then Has_Address_Clause (Prefix (Exp)));
209 end Has_Address_Clause;
211 ---------------------
212 -- Is_Formal_Array --
213 ---------------------
215 function Is_Formal_Array (Exp : Node_Id) return Boolean is
218 (Is_Entity_Name (Exp) and then Is_Formal (Entity (Exp)))
220 (Nkind (Exp) = N_Slice and then Is_Formal_Array (Prefix (Exp)));
223 ------------------------
224 -- Is_Non_Local_Array --
225 ------------------------
227 function Is_Non_Local_Array (Exp : Node_Id) return Boolean is
229 return (Is_Entity_Name (Exp)
230 and then Scope (Entity (Exp)) /= Current_Scope)
231 or else (Nkind (Exp) = N_Slice
232 and then Is_Non_Local_Array (Prefix (Exp)));
233 end Is_Non_Local_Array;
235 -- Determine if Lhs, Rhs are formal arrays or nonlocal arrays
237 Lhs_Formal : constant Boolean := Is_Formal_Array (Act_Lhs);
238 Rhs_Formal : constant Boolean := Is_Formal_Array (Act_Rhs);
240 Lhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Lhs);
241 Rhs_Non_Local_Var : constant Boolean := Is_Non_Local_Array (Act_Rhs);
243 -- Start of processing for Expand_Assign_Array
246 -- Deal with length check, note that the length check is done with
247 -- respect to the right hand side as given, not a possible underlying
248 -- renamed object, since this would generate incorrect extra checks.
250 Apply_Length_Check (Rhs, L_Type);
252 -- We start by assuming that the move can be done in either
253 -- direction, i.e. that the two sides are completely disjoint.
255 Set_Forwards_OK (N, True);
256 Set_Backwards_OK (N, True);
258 -- Normally it is only the slice case that can lead to overlap,
259 -- and explicit checks for slices are made below. But there is
260 -- one case where the slice can be implicit and invisible to us
261 -- and that is the case where we have a one dimensional array,
262 -- and either both operands are parameters, or one is a parameter
263 -- and the other is a global variable. In this case the parameter
264 -- could be a slice that overlaps with the other parameter.
266 -- Check for the case of slices requiring an explicit loop. Normally
267 -- it is only the explicit slice cases that bother us, but in the
268 -- case of one dimensional arrays, parameters can be slices that
269 -- are passed by reference, so we can have aliasing for assignments
270 -- from one parameter to another, or assignments between parameters
271 -- and nonlocal variables. However, if the array subtype is a
272 -- constrained first subtype in the parameter case, then we don't
273 -- have to worry about overlap, since slice assignments aren't
274 -- possible (other than for a slice denoting the whole array).
276 -- Note: overlap is never possible if there is a change of
277 -- representation, so we can exclude this case.
282 ((Lhs_Formal and Rhs_Formal)
284 (Lhs_Formal and Rhs_Non_Local_Var)
286 (Rhs_Formal and Lhs_Non_Local_Var))
288 (not Is_Constrained (Etype (Lhs))
289 or else not Is_First_Subtype (Etype (Lhs)))
291 -- In the case of compiling for the Java Virtual Machine,
292 -- slices are always passed by making a copy, so we don't
293 -- have to worry about overlap. We also want to prevent
294 -- generation of "<" comparisons for array addresses,
295 -- since that's a meaningless operation on the JVM.
299 Set_Forwards_OK (N, False);
300 Set_Backwards_OK (N, False);
302 -- Note: the bit-packed case is not worrisome here, since if
303 -- we have a slice passed as a parameter, it is always aligned
304 -- on a byte boundary, and if there are no explicit slices, the
305 -- assignment can be performed directly.
308 -- We certainly must use a loop for change of representation
309 -- and also we use the operand of the conversion on the right
310 -- hand side as the effective right hand side (the component
311 -- types must match in this situation).
314 Act_Rhs := Get_Referenced_Object (Rhs);
315 R_Type := Get_Actual_Subtype (Act_Rhs);
316 Loop_Required := True;
318 -- We require a loop if the left side is possibly bit unaligned
320 elsif Possible_Bit_Aligned_Component (Lhs)
322 Possible_Bit_Aligned_Component (Rhs)
324 Loop_Required := True;
326 -- Arrays with controlled components are expanded into a loop
327 -- to force calls to adjust at the component level.
329 elsif Has_Controlled_Component (L_Type) then
330 Loop_Required := True;
332 -- Case where no slice is involved
334 elsif not L_Slice and not R_Slice then
336 -- The following code deals with the case of unconstrained bit
337 -- packed arrays. The problem is that the template for such
338 -- arrays contains the bounds of the actual source level array,
340 -- But the copy of an entire array requires the bounds of the
341 -- underlying array. It would be nice if the back end could take
342 -- care of this, but right now it does not know how, so if we
343 -- have such a type, then we expand out into a loop, which is
344 -- inefficient but works correctly. If we don't do this, we
345 -- get the wrong length computed for the array to be moved.
346 -- The two cases we need to worry about are:
348 -- Explicit deference of an unconstrained packed array type as
349 -- in the following example:
352 -- type BITS is array(INTEGER range <>) of BOOLEAN;
353 -- pragma PACK(BITS);
354 -- type A is access BITS;
357 -- P1 := new BITS (1 .. 65_535);
358 -- P2 := new BITS (1 .. 65_535);
362 -- A formal parameter reference with an unconstrained bit
363 -- array type is the other case we need to worry about (here
364 -- we assume the same BITS type declared above:
366 -- procedure Write_All (File : out BITS; Contents : in BITS);
368 -- File.Storage := Contents;
371 -- We expand to a loop in either of these two cases.
373 -- Question for future thought. Another potentially more efficient
374 -- approach would be to create the actual subtype, and then do an
375 -- unchecked conversion to this actual subtype ???
377 Check_Unconstrained_Bit_Packed_Array : declare
379 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean;
380 -- Function to perform required test for the first case,
381 -- above (dereference of an unconstrained bit packed array)
383 -----------------------
384 -- Is_UBPA_Reference --
385 -----------------------
387 function Is_UBPA_Reference (Opnd : Node_Id) return Boolean is
388 Typ : constant Entity_Id := Underlying_Type (Etype (Opnd));
390 Des_Type : Entity_Id;
393 if Present (Packed_Array_Type (Typ))
394 and then Is_Array_Type (Packed_Array_Type (Typ))
395 and then not Is_Constrained (Packed_Array_Type (Typ))
399 elsif Nkind (Opnd) = N_Explicit_Dereference then
400 P_Type := Underlying_Type (Etype (Prefix (Opnd)));
402 if not Is_Access_Type (P_Type) then
406 Des_Type := Designated_Type (P_Type);
408 Is_Bit_Packed_Array (Des_Type)
409 and then not Is_Constrained (Des_Type);
415 end Is_UBPA_Reference;
417 -- Start of processing for Check_Unconstrained_Bit_Packed_Array
420 if Is_UBPA_Reference (Lhs)
422 Is_UBPA_Reference (Rhs)
424 Loop_Required := True;
426 -- Here if we do not have the case of a reference to a bit
427 -- packed unconstrained array case. In this case gigi can
428 -- most certainly handle the assignment if a forwards move
431 -- (could it handle the backwards case also???)
433 elsif Forwards_OK (N) then
436 end Check_Unconstrained_Bit_Packed_Array;
438 -- Gigi can always handle the assignment if the right side is a string
439 -- literal (note that overlap is definitely impossible in this case).
440 -- If the type is packed, a string literal is always converted into a
441 -- aggregate, except in the case of a null slice, for which no aggregate
442 -- can be written. In that case, rewrite the assignment as a null
443 -- statement, a length check has already been emitted to verify that
444 -- the range of the left-hand side is empty.
446 -- Note that this code is not executed if we had an assignment of
447 -- a string literal to a non-bit aligned component of a record, a
448 -- case which cannot be handled by the backend
450 elsif Nkind (Rhs) = N_String_Literal then
451 if String_Length (Strval (Rhs)) = 0
452 and then Is_Bit_Packed_Array (L_Type)
454 Rewrite (N, Make_Null_Statement (Loc));
460 -- If either operand is bit packed, then we need a loop, since we
461 -- can't be sure that the slice is byte aligned. Similarly, if either
462 -- operand is a possibly unaligned slice, then we need a loop (since
463 -- gigi cannot handle unaligned slices).
465 elsif Is_Bit_Packed_Array (L_Type)
466 or else Is_Bit_Packed_Array (R_Type)
467 or else Is_Possibly_Unaligned_Slice (Lhs)
468 or else Is_Possibly_Unaligned_Slice (Rhs)
470 Loop_Required := True;
472 -- If we are not bit-packed, and we have only one slice, then no
473 -- overlap is possible except in the parameter case, so we can let
474 -- gigi handle things.
476 elsif not (L_Slice and R_Slice) then
477 if Forwards_OK (N) then
482 -- If the right-hand side is a string literal, introduce a temporary
483 -- for it, for use in the generated loop that will follow.
485 if Nkind (Rhs) = N_String_Literal then
487 Temp : constant Entity_Id :=
488 Make_Defining_Identifier (Loc, Name_T);
493 Make_Object_Declaration (Loc,
494 Defining_Identifier => Temp,
495 Object_Definition => New_Occurrence_Of (L_Type, Loc),
496 Expression => Relocate_Node (Rhs));
498 Insert_Action (N, Decl);
499 Rewrite (Rhs, New_Occurrence_Of (Temp, Loc));
500 R_Type := Etype (Temp);
504 -- Come here to complete the analysis
506 -- Loop_Required: Set to True if we know that a loop is required
507 -- regardless of overlap considerations.
509 -- Forwards_OK: Set to False if we already know that a forwards
510 -- move is not safe, else set to True.
512 -- Backwards_OK: Set to False if we already know that a backwards
513 -- move is not safe, else set to True
515 -- Our task at this stage is to complete the overlap analysis, which
516 -- can result in possibly setting Forwards_OK or Backwards_OK to
517 -- False, and then generating the final code, either by deciding
518 -- that it is OK after all to let Gigi handle it, or by generating
519 -- appropriate code in the front end.
522 L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
523 R_Index_Typ : constant Node_Id := Etype (First_Index (R_Type));
525 Left_Lo : constant Node_Id := Type_Low_Bound (L_Index_Typ);
526 Left_Hi : constant Node_Id := Type_High_Bound (L_Index_Typ);
527 Right_Lo : constant Node_Id := Type_Low_Bound (R_Index_Typ);
528 Right_Hi : constant Node_Id := Type_High_Bound (R_Index_Typ);
530 Act_L_Array : Node_Id;
531 Act_R_Array : Node_Id;
537 Cresult : Compare_Result;
540 -- Get the expressions for the arrays. If we are dealing with a
541 -- private type, then convert to the underlying type. We can do
542 -- direct assignments to an array that is a private type, but
543 -- we cannot assign to elements of the array without this extra
544 -- unchecked conversion.
546 if Nkind (Act_Lhs) = N_Slice then
547 Larray := Prefix (Act_Lhs);
551 if Is_Private_Type (Etype (Larray)) then
554 (Underlying_Type (Etype (Larray)), Larray);
558 if Nkind (Act_Rhs) = N_Slice then
559 Rarray := Prefix (Act_Rhs);
563 if Is_Private_Type (Etype (Rarray)) then
566 (Underlying_Type (Etype (Rarray)), Rarray);
570 -- If both sides are slices, we must figure out whether
571 -- it is safe to do the move in one direction or the other
572 -- It is always safe if there is a change of representation
573 -- since obviously two arrays with different representations
574 -- cannot possibly overlap.
576 if (not Crep) and L_Slice and R_Slice then
577 Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
578 Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
580 -- If both left and right hand arrays are entity names, and
581 -- refer to different entities, then we know that the move
582 -- is safe (the two storage areas are completely disjoint).
584 if Is_Entity_Name (Act_L_Array)
585 and then Is_Entity_Name (Act_R_Array)
586 and then Entity (Act_L_Array) /= Entity (Act_R_Array)
590 -- Otherwise, we assume the worst, which is that the two
591 -- arrays are the same array. There is no need to check if
592 -- we know that is the case, because if we don't know it,
593 -- we still have to assume it!
595 -- Generally if the same array is involved, then we have
596 -- an overlapping case. We will have to really assume the
597 -- worst (i.e. set neither of the OK flags) unless we can
598 -- determine the lower or upper bounds at compile time and
602 Cresult := Compile_Time_Compare (Left_Lo, Right_Lo);
604 if Cresult = Unknown then
605 Cresult := Compile_Time_Compare (Left_Hi, Right_Hi);
609 when LT | LE | EQ => Set_Backwards_OK (N, False);
610 when GT | GE => Set_Forwards_OK (N, False);
611 when NE | Unknown => Set_Backwards_OK (N, False);
612 Set_Forwards_OK (N, False);
617 -- If after that analysis, Forwards_OK is still True, and
618 -- Loop_Required is False, meaning that we have not discovered
619 -- some non-overlap reason for requiring a loop, then we can
620 -- still let gigi handle it.
622 if not Loop_Required then
623 if Forwards_OK (N) then
628 -- Here is where a memmove would be appropriate ???
632 -- At this stage we have to generate an explicit loop, and
633 -- we have the following cases:
635 -- Forwards_OK = True
637 -- Rnn : right_index := right_index'First;
638 -- for Lnn in left-index loop
639 -- left (Lnn) := right (Rnn);
640 -- Rnn := right_index'Succ (Rnn);
643 -- Note: the above code MUST be analyzed with checks off,
644 -- because otherwise the Succ could overflow. But in any
645 -- case this is more efficient!
647 -- Forwards_OK = False, Backwards_OK = True
649 -- Rnn : right_index := right_index'Last;
650 -- for Lnn in reverse left-index loop
651 -- left (Lnn) := right (Rnn);
652 -- Rnn := right_index'Pred (Rnn);
655 -- Note: the above code MUST be analyzed with checks off,
656 -- because otherwise the Pred could overflow. But in any
657 -- case this is more efficient!
659 -- Forwards_OK = Backwards_OK = False
661 -- This only happens if we have the same array on each side. It is
662 -- possible to create situations using overlays that violate this,
663 -- but we simply do not promise to get this "right" in this case.
665 -- There are two possible subcases. If the No_Implicit_Conditionals
666 -- restriction is set, then we generate the following code:
669 -- T : constant <operand-type> := rhs;
674 -- If implicit conditionals are permitted, then we generate:
676 -- if Left_Lo <= Right_Lo then
677 -- <code for Forwards_OK = True above>
679 -- <code for Backwards_OK = True above>
682 -- Cases where either Forwards_OK or Backwards_OK is true
684 if Forwards_OK (N) or else Backwards_OK (N) then
685 if Controlled_Type (Component_Type (L_Type))
686 and then Base_Type (L_Type) = Base_Type (R_Type)
688 and then not No_Ctrl_Actions (N)
691 Proc : constant Entity_Id :=
692 TSS (Base_Type (L_Type), TSS_Slice_Assign);
696 Apply_Dereference (Larray);
697 Apply_Dereference (Rarray);
698 Actuals := New_List (
699 Duplicate_Subexpr (Larray, Name_Req => True),
700 Duplicate_Subexpr (Rarray, Name_Req => True),
701 Duplicate_Subexpr (Left_Lo, Name_Req => True),
702 Duplicate_Subexpr (Left_Hi, Name_Req => True),
703 Duplicate_Subexpr (Right_Lo, Name_Req => True),
704 Duplicate_Subexpr (Right_Hi, Name_Req => True));
708 Boolean_Literals (not Forwards_OK (N)), Loc));
711 Make_Procedure_Call_Statement (Loc,
712 Name => New_Reference_To (Proc, Loc),
713 Parameter_Associations => Actuals));
718 Expand_Assign_Array_Loop
719 (N, Larray, Rarray, L_Type, R_Type, Ndim,
720 Rev => not Forwards_OK (N)));
723 -- Case of both are false with No_Implicit_Conditionals
725 elsif Restriction_Active (No_Implicit_Conditionals) then
727 T : constant Entity_Id :=
728 Make_Defining_Identifier (Loc, Chars => Name_T);
732 Make_Block_Statement (Loc,
733 Declarations => New_List (
734 Make_Object_Declaration (Loc,
735 Defining_Identifier => T,
736 Constant_Present => True,
738 New_Occurrence_Of (Etype (Rhs), Loc),
739 Expression => Relocate_Node (Rhs))),
741 Handled_Statement_Sequence =>
742 Make_Handled_Sequence_Of_Statements (Loc,
743 Statements => New_List (
744 Make_Assignment_Statement (Loc,
745 Name => Relocate_Node (Lhs),
746 Expression => New_Occurrence_Of (T, Loc))))));
749 -- Case of both are false with implicit conditionals allowed
752 -- Before we generate this code, we must ensure that the
753 -- left and right side array types are defined. They may
754 -- be itypes, and we cannot let them be defined inside the
755 -- if, since the first use in the then may not be executed.
757 Ensure_Defined (L_Type, N);
758 Ensure_Defined (R_Type, N);
760 -- We normally compare addresses to find out which way round
761 -- to do the loop, since this is realiable, and handles the
762 -- cases of parameters, conversions etc. But we can't do that
763 -- in the bit packed case or the Java VM case, because addresses
766 if not Is_Bit_Packed_Array (L_Type) and then not Java_VM then
770 Unchecked_Convert_To (RTE (RE_Integer_Address),
771 Make_Attribute_Reference (Loc,
773 Make_Indexed_Component (Loc,
775 Duplicate_Subexpr_Move_Checks (Larray, True),
776 Expressions => New_List (
777 Make_Attribute_Reference (Loc,
781 Attribute_Name => Name_First))),
782 Attribute_Name => Name_Address)),
785 Unchecked_Convert_To (RTE (RE_Integer_Address),
786 Make_Attribute_Reference (Loc,
788 Make_Indexed_Component (Loc,
790 Duplicate_Subexpr_Move_Checks (Rarray, True),
791 Expressions => New_List (
792 Make_Attribute_Reference (Loc,
796 Attribute_Name => Name_First))),
797 Attribute_Name => Name_Address)));
799 -- For the bit packed and Java VM cases we use the bounds.
800 -- That's OK, because we don't have to worry about parameters,
801 -- since they cannot cause overlap. Perhaps we should worry
802 -- about weird slice conversions ???
805 -- Copy the bounds and reset the Analyzed flag, because the
806 -- bounds of the index type itself may be universal, and must
807 -- must be reaanalyzed to acquire the proper type for Gigi.
809 Cleft_Lo := New_Copy_Tree (Left_Lo);
810 Cright_Lo := New_Copy_Tree (Right_Lo);
811 Set_Analyzed (Cleft_Lo, False);
812 Set_Analyzed (Cright_Lo, False);
816 Left_Opnd => Cleft_Lo,
817 Right_Opnd => Cright_Lo);
820 if Controlled_Type (Component_Type (L_Type))
821 and then Base_Type (L_Type) = Base_Type (R_Type)
823 and then not No_Ctrl_Actions (N)
826 -- Call TSS procedure for array assignment, passing the
827 -- the explicit bounds of right- and left-hand side.
830 Proc : constant Node_Id :=
831 TSS (Base_Type (L_Type), TSS_Slice_Assign);
835 Apply_Dereference (Larray);
836 Apply_Dereference (Rarray);
837 Actuals := New_List (
838 Duplicate_Subexpr (Larray, Name_Req => True),
839 Duplicate_Subexpr (Rarray, Name_Req => True),
840 Duplicate_Subexpr (Left_Lo, Name_Req => True),
841 Duplicate_Subexpr (Left_Hi, Name_Req => True),
842 Duplicate_Subexpr (Right_Lo, Name_Req => True),
843 Duplicate_Subexpr (Right_Hi, Name_Req => True));
847 Right_Opnd => Condition));
850 Make_Procedure_Call_Statement (Loc,
851 Name => New_Reference_To (Proc, Loc),
852 Parameter_Associations => Actuals));
857 Make_Implicit_If_Statement (N,
858 Condition => Condition,
860 Then_Statements => New_List (
861 Expand_Assign_Array_Loop
862 (N, Larray, Rarray, L_Type, R_Type, Ndim,
865 Else_Statements => New_List (
866 Expand_Assign_Array_Loop
867 (N, Larray, Rarray, L_Type, R_Type, Ndim,
872 Analyze (N, Suppress => All_Checks);
876 when RE_Not_Available =>
878 end Expand_Assign_Array;
880 ------------------------------
881 -- Expand_Assign_Array_Loop --
882 ------------------------------
884 -- The following is an example of the loop generated for the case of
885 -- a two-dimensional array:
890 -- for L1b in 1 .. 100 loop
894 -- for L3b in 1 .. 100 loop
895 -- vm1 (L1b, L3b) := vm2 (R2b, R4b);
896 -- R4b := Tm1X2'succ(R4b);
899 -- R2b := Tm1X1'succ(R2b);
903 -- Here Rev is False, and Tm1Xn are the subscript types for the right
904 -- hand side. The declarations of R2b and R4b are inserted before the
905 -- original assignment statement.
907 function Expand_Assign_Array_Loop
914 Rev : Boolean) return Node_Id
916 Loc : constant Source_Ptr := Sloc (N);
918 Lnn : array (1 .. Ndim) of Entity_Id;
919 Rnn : array (1 .. Ndim) of Entity_Id;
920 -- Entities used as subscripts on left and right sides
922 L_Index_Type : array (1 .. Ndim) of Entity_Id;
923 R_Index_Type : array (1 .. Ndim) of Entity_Id;
924 -- Left and right index types
936 F_Or_L := Name_First;
940 -- Setup index types and subscript entities
947 L_Index := First_Index (L_Type);
948 R_Index := First_Index (R_Type);
950 for J in 1 .. Ndim loop
952 Make_Defining_Identifier (Loc,
953 Chars => New_Internal_Name ('L'));
956 Make_Defining_Identifier (Loc,
957 Chars => New_Internal_Name ('R'));
959 L_Index_Type (J) := Etype (L_Index);
960 R_Index_Type (J) := Etype (R_Index);
962 Next_Index (L_Index);
963 Next_Index (R_Index);
967 -- Now construct the assignment statement
970 ExprL : constant List_Id := New_List;
971 ExprR : constant List_Id := New_List;
974 for J in 1 .. Ndim loop
975 Append_To (ExprL, New_Occurrence_Of (Lnn (J), Loc));
976 Append_To (ExprR, New_Occurrence_Of (Rnn (J), Loc));
980 Make_Assignment_Statement (Loc,
982 Make_Indexed_Component (Loc,
983 Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
984 Expressions => ExprL),
986 Make_Indexed_Component (Loc,
987 Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
988 Expressions => ExprR));
990 -- Propagate the No_Ctrl_Actions flag to individual assignments
992 Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
995 -- Now construct the loop from the inside out, with the last subscript
996 -- varying most rapidly. Note that Assign is first the raw assignment
997 -- statement, and then subsequently the loop that wraps it up.
999 for J in reverse 1 .. Ndim loop
1001 Make_Block_Statement (Loc,
1002 Declarations => New_List (
1003 Make_Object_Declaration (Loc,
1004 Defining_Identifier => Rnn (J),
1005 Object_Definition =>
1006 New_Occurrence_Of (R_Index_Type (J), Loc),
1008 Make_Attribute_Reference (Loc,
1009 Prefix => New_Occurrence_Of (R_Index_Type (J), Loc),
1010 Attribute_Name => F_Or_L))),
1012 Handled_Statement_Sequence =>
1013 Make_Handled_Sequence_Of_Statements (Loc,
1014 Statements => New_List (
1015 Make_Implicit_Loop_Statement (N,
1017 Make_Iteration_Scheme (Loc,
1018 Loop_Parameter_Specification =>
1019 Make_Loop_Parameter_Specification (Loc,
1020 Defining_Identifier => Lnn (J),
1021 Reverse_Present => Rev,
1022 Discrete_Subtype_Definition =>
1023 New_Reference_To (L_Index_Type (J), Loc))),
1025 Statements => New_List (
1028 Make_Assignment_Statement (Loc,
1029 Name => New_Occurrence_Of (Rnn (J), Loc),
1031 Make_Attribute_Reference (Loc,
1033 New_Occurrence_Of (R_Index_Type (J), Loc),
1034 Attribute_Name => S_Or_P,
1035 Expressions => New_List (
1036 New_Occurrence_Of (Rnn (J), Loc)))))))));
1040 end Expand_Assign_Array_Loop;
1042 --------------------------
1043 -- Expand_Assign_Record --
1044 --------------------------
1046 -- The only processing required is in the change of representation
1047 -- case, where we must expand the assignment to a series of field
1048 -- by field assignments.
1050 procedure Expand_Assign_Record (N : Node_Id) is
1051 Lhs : constant Node_Id := Name (N);
1052 Rhs : Node_Id := Expression (N);
1055 -- If change of representation, then extract the real right hand
1056 -- side from the type conversion, and proceed with component-wise
1057 -- assignment, since the two types are not the same as far as the
1058 -- back end is concerned.
1060 if Change_Of_Representation (N) then
1061 Rhs := Expression (Rhs);
1063 -- If this may be a case of a large bit aligned component, then
1064 -- proceed with component-wise assignment, to avoid possible
1065 -- clobbering of other components sharing bits in the first or
1066 -- last byte of the component to be assigned.
1068 elsif Possible_Bit_Aligned_Component (Lhs)
1070 Possible_Bit_Aligned_Component (Rhs)
1074 -- If neither condition met, then nothing special to do, the back end
1075 -- can handle assignment of the entire component as a single entity.
1081 -- At this stage we know that we must do a component wise assignment
1084 Loc : constant Source_Ptr := Sloc (N);
1085 R_Typ : constant Entity_Id := Base_Type (Etype (Rhs));
1086 L_Typ : constant Entity_Id := Base_Type (Etype (Lhs));
1087 Decl : constant Node_Id := Declaration_Node (R_Typ);
1091 function Find_Component
1093 Comp : Entity_Id) return Entity_Id;
1094 -- Find the component with the given name in the underlying record
1095 -- declaration for Typ. We need to use the actual entity because
1096 -- the type may be private and resolution by identifier alone would
1099 function Make_Component_List_Assign (CL : Node_Id) return List_Id;
1100 -- Returns a sequence of statements to assign the components that
1101 -- are referenced in the given component list.
1103 function Make_Field_Assign (C : Entity_Id) return Node_Id;
1104 -- Given C, the entity for a discriminant or component, build
1105 -- an assignment for the corresponding field values.
1107 function Make_Field_Assigns (CI : List_Id) return List_Id;
1108 -- Given CI, a component items list, construct series of statements
1109 -- for fieldwise assignment of the corresponding components.
1111 --------------------
1112 -- Find_Component --
1113 --------------------
1115 function Find_Component
1117 Comp : Entity_Id) return Entity_Id
1119 Utyp : constant Entity_Id := Underlying_Type (Typ);
1123 C := First_Entity (Utyp);
1125 while Present (C) loop
1126 if Chars (C) = Chars (Comp) then
1132 raise Program_Error;
1135 --------------------------------
1136 -- Make_Component_List_Assign --
1137 --------------------------------
1139 function Make_Component_List_Assign (CL : Node_Id) return List_Id is
1140 CI : constant List_Id := Component_Items (CL);
1141 VP : constant Node_Id := Variant_Part (CL);
1150 Result := Make_Field_Assigns (CI);
1152 if Present (VP) then
1154 V := First_Non_Pragma (Variants (VP));
1156 while Present (V) loop
1159 DC := First (Discrete_Choices (V));
1160 while Present (DC) loop
1161 Append_To (DCH, New_Copy_Tree (DC));
1166 Make_Case_Statement_Alternative (Loc,
1167 Discrete_Choices => DCH,
1169 Make_Component_List_Assign (Component_List (V))));
1170 Next_Non_Pragma (V);
1174 Make_Case_Statement (Loc,
1176 Make_Selected_Component (Loc,
1177 Prefix => Duplicate_Subexpr (Rhs),
1179 Make_Identifier (Loc, Chars (Name (VP)))),
1180 Alternatives => Alts));
1185 end Make_Component_List_Assign;
1187 -----------------------
1188 -- Make_Field_Assign --
1189 -----------------------
1191 function Make_Field_Assign (C : Entity_Id) return Node_Id is
1196 Make_Assignment_Statement (Loc,
1198 Make_Selected_Component (Loc,
1199 Prefix => Duplicate_Subexpr (Lhs),
1201 New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
1203 Make_Selected_Component (Loc,
1204 Prefix => Duplicate_Subexpr (Rhs),
1205 Selector_Name => New_Occurrence_Of (C, Loc)));
1207 -- Set Assignment_OK, so discriminants can be assigned
1209 Set_Assignment_OK (Name (A), True);
1211 end Make_Field_Assign;
1213 ------------------------
1214 -- Make_Field_Assigns --
1215 ------------------------
1217 function Make_Field_Assigns (CI : List_Id) return List_Id is
1225 while Present (Item) loop
1226 if Nkind (Item) = N_Component_Declaration then
1228 (Result, Make_Field_Assign (Defining_Identifier (Item)));
1235 end Make_Field_Assigns;
1237 -- Start of processing for Expand_Assign_Record
1240 -- Note that we use the base types for this processing. This results
1241 -- in some extra work in the constrained case, but the change of
1242 -- representation case is so unusual that it is not worth the effort.
1244 -- First copy the discriminants. This is done unconditionally. It
1245 -- is required in the unconstrained left side case, and also in the
1246 -- case where this assignment was constructed during the expansion
1247 -- of a type conversion (since initialization of discriminants is
1248 -- suppressed in this case). It is unnecessary but harmless in
1251 if Has_Discriminants (L_Typ) then
1252 F := First_Discriminant (R_Typ);
1253 while Present (F) loop
1254 Insert_Action (N, Make_Field_Assign (F));
1255 Next_Discriminant (F);
1259 -- We know the underlying type is a record, but its current view
1260 -- may be private. We must retrieve the usable record declaration.
1262 if Nkind (Decl) = N_Private_Type_Declaration
1263 and then Present (Full_View (R_Typ))
1265 RDef := Type_Definition (Declaration_Node (Full_View (R_Typ)));
1267 RDef := Type_Definition (Decl);
1270 if Nkind (RDef) = N_Record_Definition
1271 and then Present (Component_List (RDef))
1274 (N, Make_Component_List_Assign (Component_List (RDef)));
1276 Rewrite (N, Make_Null_Statement (Loc));
1280 end Expand_Assign_Record;
1282 -----------------------------------
1283 -- Expand_N_Assignment_Statement --
1284 -----------------------------------
1286 -- For array types, deal with slice assignments and setting the flags
1287 -- to indicate if it can be statically determined which direction the
1288 -- move should go in. Also deal with generating range/length checks.
1290 procedure Expand_N_Assignment_Statement (N : Node_Id) is
1291 Loc : constant Source_Ptr := Sloc (N);
1292 Lhs : constant Node_Id := Name (N);
1293 Rhs : constant Node_Id := Expression (N);
1294 Typ : constant Entity_Id := Underlying_Type (Etype (Lhs));
1298 -- First deal with generation of range check if required. For now
1299 -- we do this only for discrete types.
1301 if Do_Range_Check (Rhs)
1302 and then Is_Discrete_Type (Typ)
1304 Set_Do_Range_Check (Rhs, False);
1305 Generate_Range_Check (Rhs, Typ, CE_Range_Check_Failed);
1308 -- Check for a special case where a high level transformation is
1309 -- required. If we have either of:
1314 -- where P is a reference to a bit packed array, then we have to unwind
1315 -- the assignment. The exact meaning of being a reference to a bit
1316 -- packed array is as follows:
1318 -- An indexed component whose prefix is a bit packed array is a
1319 -- reference to a bit packed array.
1321 -- An indexed component or selected component whose prefix is a
1322 -- reference to a bit packed array is itself a reference ot a
1323 -- bit packed array.
1325 -- The required transformation is
1327 -- Tnn : prefix_type := P;
1328 -- Tnn.field := rhs;
1333 -- Tnn : prefix_type := P;
1334 -- Tnn (subscr) := rhs;
1337 -- Since P is going to be evaluated more than once, any subscripts
1338 -- in P must have their evaluation forced.
1340 if (Nkind (Lhs) = N_Indexed_Component
1342 Nkind (Lhs) = N_Selected_Component)
1343 and then Is_Ref_To_Bit_Packed_Array (Prefix (Lhs))
1346 BPAR_Expr : constant Node_Id := Relocate_Node (Prefix (Lhs));
1347 BPAR_Typ : constant Entity_Id := Etype (BPAR_Expr);
1348 Tnn : constant Entity_Id :=
1349 Make_Defining_Identifier (Loc,
1350 Chars => New_Internal_Name ('T'));
1353 -- Insert the post assignment first, because we want to copy
1354 -- the BPAR_Expr tree before it gets analyzed in the context
1355 -- of the pre assignment. Note that we do not analyze the
1356 -- post assignment yet (we cannot till we have completed the
1357 -- analysis of the pre assignment). As usual, the analysis
1358 -- of this post assignment will happen on its own when we
1359 -- "run into" it after finishing the current assignment.
1362 Make_Assignment_Statement (Loc,
1363 Name => New_Copy_Tree (BPAR_Expr),
1364 Expression => New_Occurrence_Of (Tnn, Loc)));
1366 -- At this stage BPAR_Expr is a reference to a bit packed
1367 -- array where the reference was not expanded in the original
1368 -- tree, since it was on the left side of an assignment. But
1369 -- in the pre-assignment statement (the object definition),
1370 -- BPAR_Expr will end up on the right hand side, and must be
1371 -- reexpanded. To achieve this, we reset the analyzed flag
1372 -- of all selected and indexed components down to the actual
1373 -- indexed component for the packed array.
1377 Set_Analyzed (Exp, False);
1379 if Nkind (Exp) = N_Selected_Component
1381 Nkind (Exp) = N_Indexed_Component
1383 Exp := Prefix (Exp);
1389 -- Now we can insert and analyze the pre-assignment.
1391 -- If the right-hand side requires a transient scope, it has
1392 -- already been placed on the stack. However, the declaration is
1393 -- inserted in the tree outside of this scope, and must reflect
1394 -- the proper scope for its variable. This awkward bit is forced
1395 -- by the stricter scope discipline imposed by GCC 2.97.
1398 Uses_Transient_Scope : constant Boolean :=
1399 Scope_Is_Transient and then N = Node_To_Be_Wrapped;
1402 if Uses_Transient_Scope then
1403 New_Scope (Scope (Current_Scope));
1406 Insert_Before_And_Analyze (N,
1407 Make_Object_Declaration (Loc,
1408 Defining_Identifier => Tnn,
1409 Object_Definition => New_Occurrence_Of (BPAR_Typ, Loc),
1410 Expression => BPAR_Expr));
1412 if Uses_Transient_Scope then
1417 -- Now fix up the original assignment and continue processing
1419 Rewrite (Prefix (Lhs),
1420 New_Occurrence_Of (Tnn, Loc));
1422 -- We do not need to reanalyze that assignment, and we do not need
1423 -- to worry about references to the temporary, but we do need to
1424 -- make sure that the temporary is not marked as a true constant
1425 -- since we now have a generate assignment to it!
1427 Set_Is_True_Constant (Tnn, False);
1431 -- When we have the appropriate type of aggregate in the
1432 -- expression (it has been determined during analysis of the
1433 -- aggregate by setting the delay flag), let's perform in place
1434 -- assignment and thus avoid creating a temporay.
1436 if Is_Delayed_Aggregate (Rhs) then
1437 Convert_Aggr_In_Assignment (N);
1438 Rewrite (N, Make_Null_Statement (Loc));
1443 -- Apply discriminant check if required. If Lhs is an access type
1444 -- to a designated type with discriminants, we must always check.
1446 if Has_Discriminants (Etype (Lhs)) then
1448 -- Skip discriminant check if change of representation. Will be
1449 -- done when the change of representation is expanded out.
1451 if not Change_Of_Representation (N) then
1452 Apply_Discriminant_Check (Rhs, Etype (Lhs), Lhs);
1455 -- If the type is private without discriminants, and the full type
1456 -- has discriminants (necessarily with defaults) a check may still be
1457 -- necessary if the Lhs is aliased. The private determinants must be
1458 -- visible to build the discriminant constraints.
1460 -- Only an explicit dereference that comes from source indicates
1461 -- aliasing. Access to formals of protected operations and entries
1462 -- create dereferences but are not semantic aliasings.
1464 elsif Is_Private_Type (Etype (Lhs))
1465 and then Has_Discriminants (Typ)
1466 and then Nkind (Lhs) = N_Explicit_Dereference
1467 and then Comes_From_Source (Lhs)
1470 Lt : constant Entity_Id := Etype (Lhs);
1472 Set_Etype (Lhs, Typ);
1473 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1474 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1475 Set_Etype (Lhs, Lt);
1478 -- If the Lhs has a private type with unknown discriminants, it
1479 -- may have a full view with discriminants, but those are nameable
1480 -- only in the underlying type, so convert the Rhs to it before
1481 -- potential checking.
1483 elsif Has_Unknown_Discriminants (Base_Type (Etype (Lhs)))
1484 and then Has_Discriminants (Typ)
1486 Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
1487 Apply_Discriminant_Check (Rhs, Typ, Lhs);
1489 -- In the access type case, we need the same discriminant check,
1490 -- and also range checks if we have an access to constrained array.
1492 elsif Is_Access_Type (Etype (Lhs))
1493 and then Is_Constrained (Designated_Type (Etype (Lhs)))
1495 if Has_Discriminants (Designated_Type (Etype (Lhs))) then
1497 -- Skip discriminant check if change of representation. Will be
1498 -- done when the change of representation is expanded out.
1500 if not Change_Of_Representation (N) then
1501 Apply_Discriminant_Check (Rhs, Etype (Lhs));
1504 elsif Is_Array_Type (Designated_Type (Etype (Lhs))) then
1505 Apply_Range_Check (Rhs, Etype (Lhs));
1507 if Is_Constrained (Etype (Lhs)) then
1508 Apply_Length_Check (Rhs, Etype (Lhs));
1511 if Nkind (Rhs) = N_Allocator then
1513 Target_Typ : constant Entity_Id := Etype (Expression (Rhs));
1514 C_Es : Check_Result;
1521 Etype (Designated_Type (Etype (Lhs))));
1533 -- Apply range check for access type case
1535 elsif Is_Access_Type (Etype (Lhs))
1536 and then Nkind (Rhs) = N_Allocator
1537 and then Nkind (Expression (Rhs)) = N_Qualified_Expression
1539 Analyze_And_Resolve (Expression (Rhs));
1541 (Expression (Rhs), Designated_Type (Etype (Lhs)));
1544 -- Ada 2005 (AI-231): Generate conversion to the null-excluding
1545 -- type to force the corresponding run-time check
1547 if Is_Access_Type (Typ)
1549 ((Is_Entity_Name (Lhs) and then Can_Never_Be_Null (Entity (Lhs)))
1550 or else Can_Never_Be_Null (Etype (Lhs)))
1552 Rewrite (Rhs, Convert_To (Etype (Lhs),
1553 Relocate_Node (Rhs)));
1554 Analyze_And_Resolve (Rhs, Etype (Lhs));
1557 -- If we are assigning an access type and the left side is an
1558 -- entity, then make sure that Is_Known_Non_Null properly
1559 -- reflects the state of the entity after the assignment
1561 if Is_Access_Type (Typ)
1562 and then Is_Entity_Name (Lhs)
1563 and then Known_Non_Null (Rhs)
1564 and then Safe_To_Capture_Value (N, Entity (Lhs))
1566 Set_Is_Known_Non_Null (Entity (Lhs), Known_Non_Null (Rhs));
1569 -- Case of assignment to a bit packed array element
1571 if Nkind (Lhs) = N_Indexed_Component
1572 and then Is_Bit_Packed_Array (Etype (Prefix (Lhs)))
1574 Expand_Bit_Packed_Element_Set (N);
1577 -- Case of tagged type assignment
1579 elsif Is_Tagged_Type (Typ)
1580 or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ))
1582 Tagged_Case : declare
1583 L : List_Id := No_List;
1584 Expand_Ctrl_Actions : constant Boolean := not No_Ctrl_Actions (N);
1587 -- In the controlled case, we need to make sure that function
1588 -- calls are evaluated before finalizing the target. In all
1589 -- cases, it makes the expansion easier if the side-effects
1590 -- are removed first.
1592 Remove_Side_Effects (Lhs);
1593 Remove_Side_Effects (Rhs);
1595 -- Avoid recursion in the mechanism
1599 -- If dispatching assignment, we need to dispatch to _assign
1601 if Is_Class_Wide_Type (Typ)
1603 -- If the type is tagged, we may as well use the predefined
1604 -- primitive assignment. This avoids inlining a lot of code
1605 -- and in the class-wide case, the assignment is replaced by
1606 -- a dispatch call to _assign. Note that this cannot be done
1607 -- when discriminant checks are locally suppressed (as in
1608 -- extension aggregate expansions) because otherwise the
1609 -- discriminant check will be performed within the _assign
1612 or else (Is_Tagged_Type (Typ)
1613 and then Chars (Current_Scope) /= Name_uAssign
1614 and then Expand_Ctrl_Actions
1615 and then not Discriminant_Checks_Suppressed (Empty))
1617 -- Fetch the primitive op _assign and proper type to call
1618 -- it. Because of possible conflits between private and
1619 -- full view the proper type is fetched directly from the
1620 -- operation profile.
1623 Op : constant Entity_Id :=
1624 Find_Prim_Op (Typ, Name_uAssign);
1625 F_Typ : Entity_Id := Etype (First_Formal (Op));
1628 -- If the assignment is dispatching, make sure to use the
1629 -- ??? where is rest of this comment ???
1631 if Is_Class_Wide_Type (Typ) then
1632 F_Typ := Class_Wide_Type (F_Typ);
1636 Make_Procedure_Call_Statement (Loc,
1637 Name => New_Reference_To (Op, Loc),
1638 Parameter_Associations => New_List (
1639 Unchecked_Convert_To (F_Typ, Duplicate_Subexpr (Lhs)),
1640 Unchecked_Convert_To (F_Typ,
1641 Duplicate_Subexpr (Rhs)))));
1645 L := Make_Tag_Ctrl_Assignment (N);
1647 -- We can't afford to have destructive Finalization Actions
1648 -- in the Self assignment case, so if the target and the
1649 -- source are not obviously different, code is generated to
1650 -- avoid the self assignment case
1652 -- if lhs'address /= rhs'address then
1653 -- <code for controlled and/or tagged assignment>
1656 if not Statically_Different (Lhs, Rhs)
1657 and then Expand_Ctrl_Actions
1660 Make_Implicit_If_Statement (N,
1664 Make_Attribute_Reference (Loc,
1665 Prefix => Duplicate_Subexpr (Lhs),
1666 Attribute_Name => Name_Address),
1669 Make_Attribute_Reference (Loc,
1670 Prefix => Duplicate_Subexpr (Rhs),
1671 Attribute_Name => Name_Address)),
1673 Then_Statements => L));
1676 -- We need to set up an exception handler for implementing
1677 -- 7.6.1 (18). The remaining adjustments are tackled by the
1678 -- implementation of adjust for record_controllers (see
1681 -- This is skipped if we have no finalization
1683 if Expand_Ctrl_Actions
1684 and then not Restriction_Active (No_Finalization)
1687 Make_Block_Statement (Loc,
1688 Handled_Statement_Sequence =>
1689 Make_Handled_Sequence_Of_Statements (Loc,
1691 Exception_Handlers => New_List (
1692 Make_Exception_Handler (Loc,
1693 Exception_Choices =>
1694 New_List (Make_Others_Choice (Loc)),
1695 Statements => New_List (
1696 Make_Raise_Program_Error (Loc,
1698 PE_Finalize_Raised_Exception)
1704 Make_Block_Statement (Loc,
1705 Handled_Statement_Sequence =>
1706 Make_Handled_Sequence_Of_Statements (Loc, Statements => L)));
1708 -- If no restrictions on aborts, protect the whole assignement
1709 -- for controlled objects as per 9.8(11)
1711 if Controlled_Type (Typ)
1712 and then Expand_Ctrl_Actions
1713 and then Abort_Allowed
1716 Blk : constant Entity_Id :=
1717 New_Internal_Entity (
1718 E_Block, Current_Scope, Sloc (N), 'B');
1721 Set_Scope (Blk, Current_Scope);
1722 Set_Etype (Blk, Standard_Void_Type);
1723 Set_Identifier (N, New_Occurrence_Of (Blk, Sloc (N)));
1725 Prepend_To (L, Build_Runtime_Call (Loc, RE_Abort_Defer));
1726 Set_At_End_Proc (Handled_Statement_Sequence (N),
1727 New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc));
1728 Expand_At_End_Handler
1729 (Handled_Statement_Sequence (N), Blk);
1739 elsif Is_Array_Type (Typ) then
1741 Actual_Rhs : Node_Id := Rhs;
1744 while Nkind (Actual_Rhs) = N_Type_Conversion
1746 Nkind (Actual_Rhs) = N_Qualified_Expression
1748 Actual_Rhs := Expression (Actual_Rhs);
1751 Expand_Assign_Array (N, Actual_Rhs);
1757 elsif Is_Record_Type (Typ) then
1758 Expand_Assign_Record (N);
1761 -- Scalar types. This is where we perform the processing related
1762 -- to the requirements of (RM 13.9.1(9-11)) concerning the handling
1763 -- of invalid scalar values.
1765 elsif Is_Scalar_Type (Typ) then
1767 -- Case where right side is known valid
1769 if Expr_Known_Valid (Rhs) then
1771 -- Here the right side is valid, so it is fine. The case to
1772 -- deal with is when the left side is a local variable reference
1773 -- whose value is not currently known to be valid. If this is
1774 -- the case, and the assignment appears in an unconditional
1775 -- context, then we can mark the left side as now being valid.
1777 if Is_Local_Variable_Reference (Lhs)
1778 and then not Is_Known_Valid (Entity (Lhs))
1779 and then In_Unconditional_Context (N)
1781 Set_Is_Known_Valid (Entity (Lhs), True);
1784 -- Case where right side may be invalid in the sense of the RM
1785 -- reference above. The RM does not require that we check for
1786 -- the validity on an assignment, but it does require that the
1787 -- assignment of an invalid value not cause erroneous behavior.
1789 -- The general approach in GNAT is to use the Is_Known_Valid flag
1790 -- to avoid the need for validity checking on assignments. However
1791 -- in some cases, we have to do validity checking in order to make
1792 -- sure that the setting of this flag is correct.
1795 -- Validate right side if we are validating copies
1797 if Validity_Checks_On
1798 and then Validity_Check_Copies
1802 -- We can propagate this to the left side where appropriate
1804 if Is_Local_Variable_Reference (Lhs)
1805 and then not Is_Known_Valid (Entity (Lhs))
1806 and then In_Unconditional_Context (N)
1808 Set_Is_Known_Valid (Entity (Lhs), True);
1811 -- Otherwise check to see what should be done
1813 -- If left side is a local variable, then we just set its
1814 -- flag to indicate that its value may no longer be valid,
1815 -- since we are copying a potentially invalid value.
1817 elsif Is_Local_Variable_Reference (Lhs) then
1818 Set_Is_Known_Valid (Entity (Lhs), False);
1820 -- Check for case of a nonlocal variable on the left side
1821 -- which is currently known to be valid. In this case, we
1822 -- simply ensure that the right side is valid. We only play
1823 -- the game of copying validity status for local variables,
1824 -- since we are doing this statically, not by tracing the
1827 elsif Is_Entity_Name (Lhs)
1828 and then Is_Known_Valid (Entity (Lhs))
1830 -- Note that the Ensure_Valid call is ignored if the
1831 -- Validity_Checking mode is set to none so we do not
1832 -- need to worry about that case here.
1836 -- In all other cases, we can safely copy an invalid value
1837 -- without worrying about the status of the left side. Since
1838 -- it is not a variable reference it will not be considered
1839 -- as being known to be valid in any case.
1847 -- Defend against invalid subscripts on left side if we are in
1848 -- standard validity checking mode. No need to do this if we
1849 -- are checking all subscripts.
1851 if Validity_Checks_On
1852 and then Validity_Check_Default
1853 and then not Validity_Check_Subscripts
1855 Check_Valid_Lvalue_Subscripts (Lhs);
1859 when RE_Not_Available =>
1861 end Expand_N_Assignment_Statement;
1863 ------------------------------
1864 -- Expand_N_Block_Statement --
1865 ------------------------------
1867 -- Encode entity names defined in block statement
1869 procedure Expand_N_Block_Statement (N : Node_Id) is
1871 Qualify_Entity_Names (N);
1872 end Expand_N_Block_Statement;
1874 -----------------------------
1875 -- Expand_N_Case_Statement --
1876 -----------------------------
1878 procedure Expand_N_Case_Statement (N : Node_Id) is
1879 Loc : constant Source_Ptr := Sloc (N);
1880 Expr : constant Node_Id := Expression (N);
1888 -- Check for the situation where we know at compile time which
1889 -- branch will be taken
1891 if Compile_Time_Known_Value (Expr) then
1892 Alt := Find_Static_Alternative (N);
1894 -- Move the statements from this alternative after the case
1895 -- statement. They are already analyzed, so will be skipped
1898 Insert_List_After (N, Statements (Alt));
1900 -- That leaves the case statement as a shell. The alternative
1901 -- that will be executed is reset to a null list. So now we can
1902 -- kill the entire case statement.
1904 Kill_Dead_Code (Expression (N));
1905 Kill_Dead_Code (Alternatives (N));
1906 Rewrite (N, Make_Null_Statement (Loc));
1910 -- Here if the choice is not determined at compile time
1913 Last_Alt : constant Node_Id := Last (Alternatives (N));
1915 Others_Present : Boolean;
1916 Others_Node : Node_Id;
1918 Then_Stms : List_Id;
1919 Else_Stms : List_Id;
1922 if Nkind (First (Discrete_Choices (Last_Alt))) = N_Others_Choice then
1923 Others_Present := True;
1924 Others_Node := Last_Alt;
1926 Others_Present := False;
1929 -- First step is to worry about possible invalid argument. The RM
1930 -- requires (RM 5.4(13)) that if the result is invalid (e.g. it is
1931 -- outside the base range), then Constraint_Error must be raised.
1933 -- Case of validity check required (validity checks are on, the
1934 -- expression is not known to be valid, and the case statement
1935 -- comes from source -- no need to validity check internally
1936 -- generated case statements).
1938 if Validity_Check_Default then
1939 Ensure_Valid (Expr);
1942 -- If there is only a single alternative, just replace it with
1943 -- the sequence of statements since obviously that is what is
1944 -- going to be executed in all cases.
1946 Len := List_Length (Alternatives (N));
1949 -- We still need to evaluate the expression if it has any
1952 Remove_Side_Effects (Expression (N));
1954 Insert_List_After (N, Statements (First (Alternatives (N))));
1956 -- That leaves the case statement as a shell. The alternative
1957 -- that will be executed is reset to a null list. So now we can
1958 -- kill the entire case statement.
1960 Kill_Dead_Code (Expression (N));
1961 Rewrite (N, Make_Null_Statement (Loc));
1965 -- An optimization. If there are only two alternatives, and only
1966 -- a single choice, then rewrite the whole case statement as an
1967 -- if statement, since this can result in susbequent optimizations.
1968 -- This helps not only with case statements in the source of a
1969 -- simple form, but also with generated code (discriminant check
1970 -- functions in particular)
1973 Chlist := Discrete_Choices (First (Alternatives (N)));
1975 if List_Length (Chlist) = 1 then
1976 Choice := First (Chlist);
1978 Then_Stms := Statements (First (Alternatives (N)));
1979 Else_Stms := Statements (Last (Alternatives (N)));
1981 -- For TRUE, generate "expression", not expression = true
1983 if Nkind (Choice) = N_Identifier
1984 and then Entity (Choice) = Standard_True
1986 Cond := Expression (N);
1988 -- For FALSE, generate "expression" and switch then/else
1990 elsif Nkind (Choice) = N_Identifier
1991 and then Entity (Choice) = Standard_False
1993 Cond := Expression (N);
1994 Else_Stms := Statements (First (Alternatives (N)));
1995 Then_Stms := Statements (Last (Alternatives (N)));
1997 -- For a range, generate "expression in range"
1999 elsif Nkind (Choice) = N_Range
2000 or else (Nkind (Choice) = N_Attribute_Reference
2001 and then Attribute_Name (Choice) = Name_Range)
2002 or else (Is_Entity_Name (Choice)
2003 and then Is_Type (Entity (Choice)))
2004 or else Nkind (Choice) = N_Subtype_Indication
2008 Left_Opnd => Expression (N),
2009 Right_Opnd => Relocate_Node (Choice));
2011 -- For any other subexpression "expression = value"
2016 Left_Opnd => Expression (N),
2017 Right_Opnd => Relocate_Node (Choice));
2020 -- Now rewrite the case as an IF
2023 Make_If_Statement (Loc,
2025 Then_Statements => Then_Stms,
2026 Else_Statements => Else_Stms));
2032 -- If the last alternative is not an Others choice, replace it
2033 -- with an N_Others_Choice. Note that we do not bother to call
2034 -- Analyze on the modified case statement, since it's only effect
2035 -- would be to compute the contents of the Others_Discrete_Choices
2036 -- which is not needed by the back end anyway.
2038 -- The reason we do this is that the back end always needs some
2039 -- default for a switch, so if we have not supplied one in the
2040 -- processing above for validity checking, then we need to
2043 if not Others_Present then
2044 Others_Node := Make_Others_Choice (Sloc (Last_Alt));
2045 Set_Others_Discrete_Choices
2046 (Others_Node, Discrete_Choices (Last_Alt));
2047 Set_Discrete_Choices (Last_Alt, New_List (Others_Node));
2050 end Expand_N_Case_Statement;
2052 -----------------------------
2053 -- Expand_N_Exit_Statement --
2054 -----------------------------
2056 -- The only processing required is to deal with a possible C/Fortran
2057 -- boolean value used as the condition for the exit statement.
2059 procedure Expand_N_Exit_Statement (N : Node_Id) is
2061 Adjust_Condition (Condition (N));
2062 end Expand_N_Exit_Statement;
2064 -----------------------------
2065 -- Expand_N_Goto_Statement --
2066 -----------------------------
2068 -- Add poll before goto if polling active
2070 procedure Expand_N_Goto_Statement (N : Node_Id) is
2072 Generate_Poll_Call (N);
2073 end Expand_N_Goto_Statement;
2075 ---------------------------
2076 -- Expand_N_If_Statement --
2077 ---------------------------
2079 -- First we deal with the case of C and Fortran convention boolean
2080 -- values, with zero/non-zero semantics.
2082 -- Second, we deal with the obvious rewriting for the cases where the
2083 -- condition of the IF is known at compile time to be True or False.
2085 -- Third, we remove elsif parts which have non-empty Condition_Actions
2086 -- and rewrite as independent if statements. For example:
2097 -- <<condition actions of y>>
2103 -- This rewriting is needed if at least one elsif part has a non-empty
2104 -- Condition_Actions list. We also do the same processing if there is
2105 -- a constant condition in an elsif part (in conjunction with the first
2106 -- processing step mentioned above, for the recursive call made to deal
2107 -- with the created inner if, this deals with properly optimizing the
2108 -- cases of constant elsif conditions).
2110 procedure Expand_N_If_Statement (N : Node_Id) is
2111 Loc : constant Source_Ptr := Sloc (N);
2117 Adjust_Condition (Condition (N));
2119 -- The following loop deals with constant conditions for the IF. We
2120 -- need a loop because as we eliminate False conditions, we grab the
2121 -- first elsif condition and use it as the primary condition.
2123 while Compile_Time_Known_Value (Condition (N)) loop
2125 -- If condition is True, we can simply rewrite the if statement
2126 -- now by replacing it by the series of then statements.
2128 if Is_True (Expr_Value (Condition (N))) then
2130 -- All the else parts can be killed
2132 Kill_Dead_Code (Elsif_Parts (N));
2133 Kill_Dead_Code (Else_Statements (N));
2135 Hed := Remove_Head (Then_Statements (N));
2136 Insert_List_After (N, Then_Statements (N));
2140 -- If condition is False, then we can delete the condition and
2141 -- the Then statements
2144 -- We do not delete the condition if constant condition
2145 -- warnings are enabled, since otherwise we end up deleting
2146 -- the desired warning. Of course the backend will get rid
2147 -- of this True/False test anyway, so nothing is lost here.
2149 if not Constant_Condition_Warnings then
2150 Kill_Dead_Code (Condition (N));
2153 Kill_Dead_Code (Then_Statements (N));
2155 -- If there are no elsif statements, then we simply replace
2156 -- the entire if statement by the sequence of else statements.
2158 if No (Elsif_Parts (N)) then
2160 if No (Else_Statements (N))
2161 or else Is_Empty_List (Else_Statements (N))
2164 Make_Null_Statement (Sloc (N)));
2167 Hed := Remove_Head (Else_Statements (N));
2168 Insert_List_After (N, Else_Statements (N));
2174 -- If there are elsif statements, the first of them becomes
2175 -- the if/then section of the rebuilt if statement This is
2176 -- the case where we loop to reprocess this copied condition.
2179 Hed := Remove_Head (Elsif_Parts (N));
2180 Insert_Actions (N, Condition_Actions (Hed));
2181 Set_Condition (N, Condition (Hed));
2182 Set_Then_Statements (N, Then_Statements (Hed));
2184 if Is_Empty_List (Elsif_Parts (N)) then
2185 Set_Elsif_Parts (N, No_List);
2191 -- Loop through elsif parts, dealing with constant conditions and
2192 -- possible expression actions that are present.
2194 if Present (Elsif_Parts (N)) then
2195 E := First (Elsif_Parts (N));
2196 while Present (E) loop
2197 Adjust_Condition (Condition (E));
2199 -- If there are condition actions, then we rewrite the if
2200 -- statement as indicated above. We also do the same rewrite
2201 -- if the condition is True or False. The further processing
2202 -- of this constant condition is then done by the recursive
2203 -- call to expand the newly created if statement
2205 if Present (Condition_Actions (E))
2206 or else Compile_Time_Known_Value (Condition (E))
2208 -- Note this is not an implicit if statement, since it is
2209 -- part of an explicit if statement in the source (or of an
2210 -- implicit if statement that has already been tested).
2213 Make_If_Statement (Sloc (E),
2214 Condition => Condition (E),
2215 Then_Statements => Then_Statements (E),
2216 Elsif_Parts => No_List,
2217 Else_Statements => Else_Statements (N));
2219 -- Elsif parts for new if come from remaining elsif's of parent
2221 while Present (Next (E)) loop
2222 if No (Elsif_Parts (New_If)) then
2223 Set_Elsif_Parts (New_If, New_List);
2226 Append (Remove_Next (E), Elsif_Parts (New_If));
2229 Set_Else_Statements (N, New_List (New_If));
2231 if Present (Condition_Actions (E)) then
2232 Insert_List_Before (New_If, Condition_Actions (E));
2237 if Is_Empty_List (Elsif_Parts (N)) then
2238 Set_Elsif_Parts (N, No_List);
2244 -- No special processing for that elsif part, move to next
2252 -- Some more optimizations applicable if we still have an IF statement
2254 if Nkind (N) /= N_If_Statement then
2258 -- Another optimization, special cases that can be simplified
2260 -- if expression then
2266 -- can be changed to:
2268 -- return expression;
2272 -- if expression then
2278 -- can be changed to:
2280 -- return not (expression);
2282 if Nkind (N) = N_If_Statement
2283 and then No (Elsif_Parts (N))
2284 and then Present (Else_Statements (N))
2285 and then List_Length (Then_Statements (N)) = 1
2286 and then List_Length (Else_Statements (N)) = 1
2289 Then_Stm : constant Node_Id := First (Then_Statements (N));
2290 Else_Stm : constant Node_Id := First (Else_Statements (N));
2293 if Nkind (Then_Stm) = N_Return_Statement
2295 Nkind (Else_Stm) = N_Return_Statement
2298 Then_Expr : constant Node_Id := Expression (Then_Stm);
2299 Else_Expr : constant Node_Id := Expression (Else_Stm);
2302 if Nkind (Then_Expr) = N_Identifier
2304 Nkind (Else_Expr) = N_Identifier
2306 if Entity (Then_Expr) = Standard_True
2307 and then Entity (Else_Expr) = Standard_False
2310 Make_Return_Statement (Loc,
2311 Expression => Relocate_Node (Condition (N))));
2315 elsif Entity (Then_Expr) = Standard_False
2316 and then Entity (Else_Expr) = Standard_True
2319 Make_Return_Statement (Loc,
2322 Right_Opnd => Relocate_Node (Condition (N)))));
2331 end Expand_N_If_Statement;
2333 -----------------------------
2334 -- Expand_N_Loop_Statement --
2335 -----------------------------
2337 -- 1. Deal with while condition for C/Fortran boolean
2338 -- 2. Deal with loops with a non-standard enumeration type range
2339 -- 3. Deal with while loops where Condition_Actions is set
2340 -- 4. Insert polling call if required
2342 procedure Expand_N_Loop_Statement (N : Node_Id) is
2343 Loc : constant Source_Ptr := Sloc (N);
2344 Isc : constant Node_Id := Iteration_Scheme (N);
2347 if Present (Isc) then
2348 Adjust_Condition (Condition (Isc));
2351 if Is_Non_Empty_List (Statements (N)) then
2352 Generate_Poll_Call (First (Statements (N)));
2359 -- Handle the case where we have a for loop with the range type being
2360 -- an enumeration type with non-standard representation. In this case
2363 -- for x in [reverse] a .. b loop
2369 -- for xP in [reverse] integer
2370 -- range etype'Pos (a) .. etype'Pos (b) loop
2372 -- x : constant etype := Pos_To_Rep (xP);
2378 if Present (Loop_Parameter_Specification (Isc)) then
2380 LPS : constant Node_Id := Loop_Parameter_Specification (Isc);
2381 Loop_Id : constant Entity_Id := Defining_Identifier (LPS);
2382 Ltype : constant Entity_Id := Etype (Loop_Id);
2383 Btype : constant Entity_Id := Base_Type (Ltype);
2388 if not Is_Enumeration_Type (Btype)
2389 or else No (Enum_Pos_To_Rep (Btype))
2395 Make_Defining_Identifier (Loc,
2396 Chars => New_External_Name (Chars (Loop_Id), 'P'));
2398 -- If the type has a contiguous representation, successive
2399 -- values can be generated as offsets from the first literal.
2401 if Has_Contiguous_Rep (Btype) then
2403 Unchecked_Convert_To (Btype,
2406 Make_Integer_Literal (Loc,
2407 Enumeration_Rep (First_Literal (Btype))),
2408 Right_Opnd => New_Reference_To (New_Id, Loc)));
2410 -- Use the constructed array Enum_Pos_To_Rep.
2413 Make_Indexed_Component (Loc,
2414 Prefix => New_Reference_To (Enum_Pos_To_Rep (Btype), Loc),
2415 Expressions => New_List (New_Reference_To (New_Id, Loc)));
2419 Make_Loop_Statement (Loc,
2420 Identifier => Identifier (N),
2423 Make_Iteration_Scheme (Loc,
2424 Loop_Parameter_Specification =>
2425 Make_Loop_Parameter_Specification (Loc,
2426 Defining_Identifier => New_Id,
2427 Reverse_Present => Reverse_Present (LPS),
2429 Discrete_Subtype_Definition =>
2430 Make_Subtype_Indication (Loc,
2433 New_Reference_To (Standard_Natural, Loc),
2436 Make_Range_Constraint (Loc,
2441 Make_Attribute_Reference (Loc,
2443 New_Reference_To (Btype, Loc),
2445 Attribute_Name => Name_Pos,
2447 Expressions => New_List (
2449 (Type_Low_Bound (Ltype)))),
2452 Make_Attribute_Reference (Loc,
2454 New_Reference_To (Btype, Loc),
2456 Attribute_Name => Name_Pos,
2458 Expressions => New_List (
2460 (Type_High_Bound (Ltype))))))))),
2462 Statements => New_List (
2463 Make_Block_Statement (Loc,
2464 Declarations => New_List (
2465 Make_Object_Declaration (Loc,
2466 Defining_Identifier => Loop_Id,
2467 Constant_Present => True,
2468 Object_Definition => New_Reference_To (Ltype, Loc),
2469 Expression => Expr)),
2471 Handled_Statement_Sequence =>
2472 Make_Handled_Sequence_Of_Statements (Loc,
2473 Statements => Statements (N)))),
2475 End_Label => End_Label (N)));
2479 -- Second case, if we have a while loop with Condition_Actions set,
2480 -- then we change it into a plain loop:
2489 -- <<condition actions>>
2495 and then Present (Condition_Actions (Isc))
2502 Make_Exit_Statement (Sloc (Condition (Isc)),
2504 Make_Op_Not (Sloc (Condition (Isc)),
2505 Right_Opnd => Condition (Isc)));
2507 Prepend (ES, Statements (N));
2508 Insert_List_Before (ES, Condition_Actions (Isc));
2510 -- This is not an implicit loop, since it is generated in
2511 -- response to the loop statement being processed. If this
2512 -- is itself implicit, the restriction has already been
2513 -- checked. If not, it is an explicit loop.
2516 Make_Loop_Statement (Sloc (N),
2517 Identifier => Identifier (N),
2518 Statements => Statements (N),
2519 End_Label => End_Label (N)));
2524 end Expand_N_Loop_Statement;
2526 -------------------------------
2527 -- Expand_N_Return_Statement --
2528 -------------------------------
2530 procedure Expand_N_Return_Statement (N : Node_Id) is
2531 Loc : constant Source_Ptr := Sloc (N);
2532 Exp : constant Node_Id := Expression (N);
2536 Scope_Id : Entity_Id;
2540 Goto_Stat : Node_Id;
2543 Return_Type : Entity_Id;
2544 Result_Exp : Node_Id;
2545 Result_Id : Entity_Id;
2546 Result_Obj : Node_Id;
2549 -- Case where returned expression is present
2551 if Present (Exp) then
2553 -- Always normalize C/Fortran boolean result. This is not always
2554 -- necessary, but it seems a good idea to minimize the passing
2555 -- around of non-normalized values, and in any case this handles
2556 -- the processing of barrier functions for protected types, which
2557 -- turn the condition into a return statement.
2559 Exptyp := Etype (Exp);
2561 if Is_Boolean_Type (Exptyp)
2562 and then Nonzero_Is_True (Exptyp)
2564 Adjust_Condition (Exp);
2565 Adjust_Result_Type (Exp, Exptyp);
2568 -- Do validity check if enabled for returns
2570 if Validity_Checks_On
2571 and then Validity_Check_Returns
2577 -- Find relevant enclosing scope from which return is returning
2579 Cur_Idx := Scope_Stack.Last;
2581 Scope_Id := Scope_Stack.Table (Cur_Idx).Entity;
2583 if Ekind (Scope_Id) /= E_Block
2584 and then Ekind (Scope_Id) /= E_Loop
2589 Cur_Idx := Cur_Idx - 1;
2590 pragma Assert (Cur_Idx >= 0);
2595 Kind := Ekind (Scope_Id);
2597 -- If it is a return from procedures do no extra steps.
2599 if Kind = E_Procedure or else Kind = E_Generic_Procedure then
2603 pragma Assert (Is_Entry (Scope_Id));
2605 -- Look at the enclosing block to see whether the return is from
2606 -- an accept statement or an entry body.
2608 for J in reverse 0 .. Cur_Idx loop
2609 Scope_Id := Scope_Stack.Table (J).Entity;
2610 exit when Is_Concurrent_Type (Scope_Id);
2613 -- If it is a return from accept statement it should be expanded
2614 -- as a call to RTS Complete_Rendezvous and a goto to the end of
2617 -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
2618 -- Expand_N_Accept_Alternative in exp_ch9.adb)
2620 if Is_Task_Type (Scope_Id) then
2622 Call := (Make_Procedure_Call_Statement (Loc,
2623 Name => New_Reference_To
2624 (RTE (RE_Complete_Rendezvous), Loc)));
2625 Insert_Before (N, Call);
2626 -- why not insert actions here???
2629 Acc_Stat := Parent (N);
2630 while Nkind (Acc_Stat) /= N_Accept_Statement loop
2631 Acc_Stat := Parent (Acc_Stat);
2634 Lab_Node := Last (Statements
2635 (Handled_Statement_Sequence (Acc_Stat)));
2637 Goto_Stat := Make_Goto_Statement (Loc,
2638 Name => New_Occurrence_Of
2639 (Entity (Identifier (Lab_Node)), Loc));
2641 Set_Analyzed (Goto_Stat);
2643 Rewrite (N, Goto_Stat);
2646 -- If it is a return from an entry body, put a Complete_Entry_Body
2647 -- call in front of the return.
2649 elsif Is_Protected_Type (Scope_Id) then
2652 Make_Procedure_Call_Statement (Loc,
2653 Name => New_Reference_To
2654 (RTE (RE_Complete_Entry_Body), Loc),
2655 Parameter_Associations => New_List
2656 (Make_Attribute_Reference (Loc,
2660 (Corresponding_Body (Parent (Scope_Id))),
2662 Attribute_Name => Name_Unchecked_Access)));
2664 Insert_Before (N, Call);
2673 Return_Type := Etype (Scope_Id);
2674 Utyp := Underlying_Type (Return_Type);
2676 -- Check the result expression of a scalar function against
2677 -- the subtype of the function by inserting a conversion.
2678 -- This conversion must eventually be performed for other
2679 -- classes of types, but for now it's only done for scalars.
2682 if Is_Scalar_Type (T) then
2683 Rewrite (Exp, Convert_To (Return_Type, Exp));
2687 -- Implement the rules of 6.5(8-10), which require a tag check in
2688 -- the case of a limited tagged return type, and tag reassignment
2689 -- for nonlimited tagged results. These actions are needed when
2690 -- the return type is a specific tagged type and the result
2691 -- expression is a conversion or a formal parameter, because in
2692 -- that case the tag of the expression might differ from the tag
2693 -- of the specific result type.
2695 if Is_Tagged_Type (Utyp)
2696 and then not Is_Class_Wide_Type (Utyp)
2697 and then (Nkind (Exp) = N_Type_Conversion
2698 or else Nkind (Exp) = N_Unchecked_Type_Conversion
2699 or else (Is_Entity_Name (Exp)
2700 and then Ekind (Entity (Exp)) in Formal_Kind))
2702 -- When the return type is limited, perform a check that the
2703 -- tag of the result is the same as the tag of the return type.
2705 if Is_Limited_Type (Return_Type) then
2707 Make_Raise_Constraint_Error (Loc,
2711 Make_Selected_Component (Loc,
2712 Prefix => Duplicate_Subexpr (Exp),
2714 New_Reference_To (Tag_Component (Utyp), Loc)),
2716 Unchecked_Convert_To (RTE (RE_Tag),
2718 (Access_Disp_Table (Base_Type (Utyp)), Loc))),
2719 Reason => CE_Tag_Check_Failed));
2721 -- If the result type is a specific nonlimited tagged type,
2722 -- then we have to ensure that the tag of the result is that
2723 -- of the result type. This is handled by making a copy of the
2724 -- expression in the case where it might have a different tag,
2725 -- namely when the expression is a conversion or a formal
2726 -- parameter. We create a new object of the result type and
2727 -- initialize it from the expression, which will implicitly
2728 -- force the tag to be set appropriately.
2732 Make_Defining_Identifier (Loc, New_Internal_Name ('R'));
2733 Result_Exp := New_Reference_To (Result_Id, Loc);
2736 Make_Object_Declaration (Loc,
2737 Defining_Identifier => Result_Id,
2738 Object_Definition => New_Reference_To (Return_Type, Loc),
2739 Constant_Present => True,
2740 Expression => Relocate_Node (Exp));
2742 Set_Assignment_OK (Result_Obj);
2743 Insert_Action (Exp, Result_Obj);
2745 Rewrite (Exp, Result_Exp);
2746 Analyze_And_Resolve (Exp, Return_Type);
2750 -- Deal with returning variable length objects and controlled types
2752 -- Nothing to do if we are returning by reference, or this is not
2753 -- a type that requires special processing (indicated by the fact
2754 -- that it requires a cleanup scope for the secondary stack case)
2756 if Is_Return_By_Reference_Type (T)
2757 or else not Requires_Transient_Scope (Return_Type)
2761 -- Case of secondary stack not used
2763 elsif Function_Returns_With_DSP (Scope_Id) then
2765 -- Here what we need to do is to always return by reference, since
2766 -- we will return with the stack pointer depressed. We may need to
2767 -- do a copy to a local temporary before doing this return.
2769 No_Secondary_Stack_Case : declare
2770 Local_Copy_Required : Boolean := False;
2771 -- Set to True if a local copy is required
2773 Copy_Ent : Entity_Id;
2774 -- Used for the target entity if a copy is required
2777 -- Declaration used to create copy if needed
2779 procedure Test_Copy_Required (Expr : Node_Id);
2780 -- Determines if Expr represents a return value for which a
2781 -- copy is required. More specifically, a copy is not required
2782 -- if Expr represents an object or component of an object that
2783 -- is either in the local subprogram frame, or is constant.
2784 -- If a copy is required, then Local_Copy_Required is set True.
2786 ------------------------
2787 -- Test_Copy_Required --
2788 ------------------------
2790 procedure Test_Copy_Required (Expr : Node_Id) is
2794 -- If component, test prefix (object containing component)
2796 if Nkind (Expr) = N_Indexed_Component
2798 Nkind (Expr) = N_Selected_Component
2800 Test_Copy_Required (Prefix (Expr));
2803 -- See if we have an entity name
2805 elsif Is_Entity_Name (Expr) then
2806 Ent := Entity (Expr);
2808 -- Constant entity is always OK, no copy required
2810 if Ekind (Ent) = E_Constant then
2813 -- No copy required for local variable
2815 elsif Ekind (Ent) = E_Variable
2816 and then Scope (Ent) = Current_Subprogram
2822 -- All other cases require a copy
2824 Local_Copy_Required := True;
2825 end Test_Copy_Required;
2827 -- Start of processing for No_Secondary_Stack_Case
2830 -- No copy needed if result is from a function call.
2831 -- In this case the result is already being returned by
2832 -- reference with the stack pointer depressed.
2834 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2835 -- the copy for array types if the constrained status of the
2836 -- target type is different from that of the expression.
2838 if Requires_Transient_Scope (T)
2840 (not Is_Array_Type (T)
2841 or else Is_Constrained (T) = Is_Constrained (Return_Type)
2842 or else Controlled_Type (T))
2843 and then Nkind (Exp) = N_Function_Call
2847 -- We always need a local copy for a controlled type, since
2848 -- we are required to finalize the local value before return.
2849 -- The copy will automatically include the required finalize.
2850 -- Moreover, gigi cannot make this copy, since we need special
2851 -- processing to ensure proper behavior for finalization.
2853 -- Note: the reason we are returning with a depressed stack
2854 -- pointer in the controlled case (even if the type involved
2855 -- is constrained) is that we must make a local copy to deal
2856 -- properly with the requirement that the local result be
2859 elsif Controlled_Type (Utyp) then
2861 Make_Defining_Identifier (Loc,
2862 Chars => New_Internal_Name ('R'));
2864 -- Build declaration to do the copy, and insert it, setting
2865 -- Assignment_OK, because we may be copying a limited type.
2866 -- In addition we set the special flag to inhibit finalize
2867 -- attachment if this is a controlled type (since this attach
2868 -- must be done by the caller, otherwise if we attach it here
2869 -- we will finalize the returned result prematurely).
2872 Make_Object_Declaration (Loc,
2873 Defining_Identifier => Copy_Ent,
2874 Object_Definition => New_Occurrence_Of (Return_Type, Loc),
2875 Expression => Relocate_Node (Exp));
2877 Set_Assignment_OK (Decl);
2878 Set_Delay_Finalize_Attach (Decl);
2879 Insert_Action (N, Decl);
2881 -- Now the actual return uses the copied value
2883 Rewrite (Exp, New_Occurrence_Of (Copy_Ent, Loc));
2884 Analyze_And_Resolve (Exp, Return_Type);
2886 -- Since we have made the copy, gigi does not have to, so
2887 -- we set the By_Ref flag to prevent another copy being made.
2891 -- Non-controlled cases
2894 Test_Copy_Required (Exp);
2896 -- If a local copy is required, then gigi will make the
2897 -- copy, otherwise, we can return the result directly,
2898 -- so set By_Ref to suppress the gigi copy.
2900 if not Local_Copy_Required then
2904 end No_Secondary_Stack_Case;
2906 -- Here if secondary stack is used
2909 -- Make sure that no surrounding block will reclaim the
2910 -- secondary-stack on which we are going to put the result.
2911 -- Not only may this introduce secondary stack leaks but worse,
2912 -- if the reclamation is done too early, then the result we are
2913 -- returning may get clobbered. See example in 7417-003.
2916 S : Entity_Id := Current_Scope;
2919 while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop
2920 Set_Sec_Stack_Needed_For_Return (S, True);
2921 S := Enclosing_Dynamic_Scope (S);
2925 -- Optimize the case where the result is a function call. In this
2926 -- case either the result is already on the secondary stack, or is
2927 -- already being returned with the stack pointer depressed and no
2928 -- further processing is required except to set the By_Ref flag to
2929 -- ensure that gigi does not attempt an extra unnecessary copy.
2930 -- (actually not just unnecessary but harmfully wrong in the case
2931 -- of a controlled type, where gigi does not know how to do a copy).
2932 -- To make up for a gcc 2.8.1 deficiency (???), we perform
2933 -- the copy for array types if the constrained status of the
2934 -- target type is different from that of the expression.
2936 if Requires_Transient_Scope (T)
2938 (not Is_Array_Type (T)
2939 or else Is_Constrained (T) = Is_Constrained (Return_Type)
2940 or else Controlled_Type (T))
2941 and then Nkind (Exp) = N_Function_Call
2945 -- For controlled types, do the allocation on the sec-stack
2946 -- manually in order to call adjust at the right time
2947 -- type Anon1 is access Return_Type;
2948 -- for Anon1'Storage_pool use ss_pool;
2949 -- Anon2 : anon1 := new Return_Type'(expr);
2950 -- return Anon2.all;
2952 elsif Controlled_Type (Utyp) then
2954 Loc : constant Source_Ptr := Sloc (N);
2955 Temp : constant Entity_Id :=
2956 Make_Defining_Identifier (Loc,
2957 Chars => New_Internal_Name ('R'));
2958 Acc_Typ : constant Entity_Id :=
2959 Make_Defining_Identifier (Loc,
2960 Chars => New_Internal_Name ('A'));
2961 Alloc_Node : Node_Id;
2964 Set_Ekind (Acc_Typ, E_Access_Type);
2966 Set_Associated_Storage_Pool (Acc_Typ, RTE (RE_SS_Pool));
2969 Make_Allocator (Loc,
2971 Make_Qualified_Expression (Loc,
2972 Subtype_Mark => New_Reference_To (Etype (Exp), Loc),
2973 Expression => Relocate_Node (Exp)));
2975 Insert_List_Before_And_Analyze (N, New_List (
2976 Make_Full_Type_Declaration (Loc,
2977 Defining_Identifier => Acc_Typ,
2979 Make_Access_To_Object_Definition (Loc,
2980 Subtype_Indication =>
2981 New_Reference_To (Return_Type, Loc))),
2983 Make_Object_Declaration (Loc,
2984 Defining_Identifier => Temp,
2985 Object_Definition => New_Reference_To (Acc_Typ, Loc),
2986 Expression => Alloc_Node)));
2989 Make_Explicit_Dereference (Loc,
2990 Prefix => New_Reference_To (Temp, Loc)));
2992 Analyze_And_Resolve (Exp, Return_Type);
2995 -- Otherwise use the gigi mechanism to allocate result on the
2999 Set_Storage_Pool (N, RTE (RE_SS_Pool));
3001 -- If we are generating code for the Java VM do not use
3002 -- SS_Allocate since everything is heap-allocated anyway.
3005 Set_Procedure_To_Call (N, RTE (RE_SS_Allocate));
3011 when RE_Not_Available =>
3013 end Expand_N_Return_Statement;
3015 ------------------------------
3016 -- Make_Tag_Ctrl_Assignment --
3017 ------------------------------
3019 function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id is
3020 Loc : constant Source_Ptr := Sloc (N);
3021 L : constant Node_Id := Name (N);
3022 T : constant Entity_Id := Underlying_Type (Etype (L));
3024 Ctrl_Act : constant Boolean := Controlled_Type (T)
3025 and then not No_Ctrl_Actions (N);
3027 Save_Tag : constant Boolean := Is_Tagged_Type (T)
3028 and then not No_Ctrl_Actions (N)
3029 and then not Java_VM;
3030 -- Tags are not saved and restored when Java_VM because JVM tags
3031 -- are represented implicitly in objects.
3034 Tag_Tmp : Entity_Id;
3035 Original_Size, Range_Type, Opaque_Type : Entity_Id;
3040 -- Finalize the target of the assignment when controlled.
3041 -- We have two exceptions here:
3043 -- 1. If we are in an init proc since it is an initialization
3044 -- more than an assignment
3046 -- 2. If the left-hand side is a temporary that was not initialized
3047 -- (or the parent part of a temporary since it is the case in
3048 -- extension aggregates). Such a temporary does not come from
3049 -- source. We must examine the original node for the prefix, because
3050 -- it may be a component of an entry formal, in which case it has
3051 -- been rewritten and does not appear to come from source either.
3053 -- Case of init proc
3055 if not Ctrl_Act then
3058 -- The left hand side is an uninitialized temporary
3060 elsif Nkind (L) = N_Type_Conversion
3061 and then Is_Entity_Name (Expression (L))
3062 and then No_Initialization (Parent (Entity (Expression (L))))
3066 Append_List_To (Res,
3068 Ref => Duplicate_Subexpr_No_Checks (L),
3070 With_Detach => New_Reference_To (Standard_False, Loc)));
3073 -- Save the Tag in a local variable Tag_Tmp
3077 Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
3080 Make_Object_Declaration (Loc,
3081 Defining_Identifier => Tag_Tmp,
3082 Object_Definition => New_Reference_To (RTE (RE_Tag), Loc),
3084 Make_Selected_Component (Loc,
3085 Prefix => Duplicate_Subexpr_No_Checks (L),
3086 Selector_Name => New_Reference_To (Tag_Component (T), Loc))));
3088 -- Otherwise Tag_Tmp not used
3094 -- We really need a comment here ???
3098 -- subtype G is Storage_Offset range 1 .. Expr'Size
3101 Make_Defining_Identifier (Loc,
3102 New_Internal_Name ('S'));
3105 Make_Object_Declaration (Loc,
3106 Defining_Identifier => Original_Size,
3107 Constant_Present => True,
3108 Object_Definition => New_Occurrence_Of (
3109 RTE (RE_Storage_Offset), Loc),
3111 Make_Op_Divide (Loc,
3113 Make_Attribute_Reference (Loc,
3115 Duplicate_Subexpr_No_Checks (L),
3116 Attribute_Name => Name_Size),
3117 Right_Opnd => Make_Integer_Literal (Loc,
3118 Intval => System_Storage_Unit))));
3121 Make_Defining_Identifier (Loc,
3122 New_Internal_Name ('G'));
3125 Make_Subtype_Declaration (Loc,
3126 Defining_Identifier => Range_Type,
3127 Subtype_Indication =>
3128 Make_Subtype_Indication (Loc,
3130 New_Reference_To (RTE (RE_Storage_Offset), Loc),
3131 Constraint => Make_Range_Constraint (Loc,
3134 Low_Bound => Make_Integer_Literal (Loc, 1),
3135 High_Bound => New_Occurrence_Of (
3136 Original_Size, Loc))))));
3138 -- subtype S is Storage_Array (G)
3141 Make_Subtype_Declaration (Loc,
3142 Defining_Identifier =>
3143 Make_Defining_Identifier (Loc,
3144 New_Internal_Name ('S')),
3145 Subtype_Indication =>
3146 Make_Subtype_Indication (Loc,
3148 New_Reference_To (RTE (RE_Storage_Array), Loc),
3150 Make_Index_Or_Discriminant_Constraint (Loc,
3152 New_List (New_Reference_To (Range_Type, Loc))))));
3154 -- type A is access S
3156 Opaque_Type := Make_Defining_Identifier (Loc,
3157 New_Internal_Name ('A'));
3159 Make_Full_Type_Declaration (Loc,
3160 Defining_Identifier => Opaque_Type,
3162 Make_Access_To_Object_Definition (Loc,
3163 Subtype_Indication =>
3165 Defining_Identifier (Last (Res)), Loc))));
3167 -- Give a label name to this declare block, and add comments here???
3172 First_After_Root : Node_Id := Empty;
3173 -- Index of first byte to be copied (used to skip
3174 -- Root_Controlled in controlled objects).
3176 Last_Before_Hole : Node_Id := Empty;
3177 -- Index of last byte to be copied before outermost record
3180 Hole_Length : Node_Id := Empty;
3181 -- Length of record controller data (Prev and Next pointers)
3183 First_After_Hole : Node_Id := Empty;
3184 -- Index of first byte to be copied after outermost record
3187 function Build_Slice
3189 Lo, Hi : Node_Id) return Node_Id;
3190 -- Function specs must have comments, saying what all the
3191 -- parameters are and what the function does ???
3197 function Build_Slice
3199 Lo, Hi : Node_Id) return Node_Id
3201 Lo_Bound, Hi_Bound : Node_Id;
3203 Opaque : constant Node_Id :=
3204 Unchecked_Convert_To (Opaque_Type,
3205 Make_Attribute_Reference (Loc,
3207 Attribute_Name => Name_Address));
3208 -- Comment required, what is this???
3211 -- Comments required in this body ???
3214 Lo_Bound := Make_Integer_Literal (Loc, 1);
3220 Hi_Bound := Make_Attribute_Reference (Loc,
3221 Prefix => New_Occurrence_Of (Range_Type, Loc),
3222 Attribute_Name => Name_Last);
3227 return Make_Slice (Loc,
3230 Discrete_Range => Make_Range (Loc,
3231 Lo_Bound, Hi_Bound));
3234 -- Start of processing for ??? (name of block)
3237 First_After_Root := Make_Integer_Literal (Loc, 1);
3241 if Is_Controlled (T) then
3245 Make_Op_Divide (Loc,
3246 Make_Attribute_Reference (Loc,
3248 New_Occurrence_Of (RTE (RE_Root_Controlled), Loc),
3249 Attribute_Name => Name_Size),
3250 Make_Integer_Literal (Loc, System_Storage_Unit)));
3253 if Has_Controlled_Component (T) then
3255 -- The record controller Prev and Next pointers must be left
3256 -- intact in the target object, not copied. Compute the bounds
3257 -- of the hole to be skipped in copying the objecct.
3260 Make_Selected_Component (Loc,
3262 Make_Selected_Component (Loc,
3263 Prefix => Duplicate_Subexpr_No_Checks (L),
3265 New_Reference_To (Controller_Component (T), Loc)),
3266 Selector_Name => Make_Identifier (Loc, Name_Prev));
3268 -- Last index before hole
3271 Make_Defining_Identifier (Loc,
3272 New_Internal_Name ('L'));
3275 Make_Object_Declaration (Loc,
3276 Defining_Identifier => Last_Before_Hole,
3277 Object_Definition => New_Occurrence_Of (
3278 RTE (RE_Storage_Offset), Loc),
3279 Constant_Present => True,
3280 Expression => Make_Op_Add (Loc,
3281 Make_Attribute_Reference (Loc,
3283 Attribute_Name => Name_Position),
3284 Make_Attribute_Reference (Loc,
3285 Prefix => New_Copy_Tree (Prefix (Prev_Ref)),
3286 Attribute_Name => Name_Position))));
3291 Make_Op_Multiply (Loc,
3292 Make_Integer_Literal (Loc, Uint_2),
3293 Make_Op_Divide (Loc,
3294 Make_Attribute_Reference (Loc,
3296 New_Copy_Tree (Prev_Ref),
3299 Make_Integer_Literal (Loc, System_Storage_Unit)));
3301 -- First index after hole
3304 Make_Defining_Identifier (Loc,
3305 New_Internal_Name ('F'));
3308 Make_Object_Declaration (Loc,
3309 Defining_Identifier => First_After_Hole,
3310 Object_Definition => New_Occurrence_Of (
3311 RTE (RE_Storage_Offset), Loc),
3312 Constant_Present => True,
3316 New_Occurrence_Of (Last_Before_Hole, Loc),
3318 Make_Integer_Literal (Loc, 1))));
3320 Last_Before_Hole := New_Occurrence_Of (Last_Before_Hole, Loc);
3321 First_After_Hole := New_Occurrence_Of (First_After_Hole, Loc);
3324 -- More comments needed everywhere ???
3326 Append_To (Res, Make_Assignment_Statement (Loc,
3327 Name => Build_Slice (Duplicate_Subexpr_No_Checks (L),
3331 Expression => Build_Slice (Expression (N),
3333 New_Copy_Tree (Last_Before_Hole))));
3336 if Present (First_After_Hole) then
3337 Remove_Side_Effects (Expression (N));
3338 Append_To (Res, Make_Assignment_Statement (Loc,
3339 Name => Build_Slice (Duplicate_Subexpr_No_Checks (L),
3342 Expression => Build_Slice (New_Copy_Tree (Expression (N)),
3343 New_Copy_Tree (First_After_Hole),
3349 Append_To (Res, Relocate_Node (N));
3356 Make_Assignment_Statement (Loc,
3358 Make_Selected_Component (Loc,
3359 Prefix => Duplicate_Subexpr_No_Checks (L),
3360 Selector_Name => New_Reference_To (Tag_Component (T), Loc)),
3361 Expression => New_Reference_To (Tag_Tmp, Loc)));
3364 -- Adjust the target after the assignment when controlled (not in the
3365 -- init proc since it is an initialization more than an assignment).
3368 Append_List_To (Res,
3370 Ref => Duplicate_Subexpr_Move_Checks (L),
3372 Flist_Ref => New_Reference_To (RTE (RE_Global_Final_List), Loc),
3373 With_Attach => Make_Integer_Literal (Loc, 0)));
3379 -- Could use comment here ???
3381 when RE_Not_Available =>
3383 end Make_Tag_Ctrl_Assignment;
3385 ------------------------------------
3386 -- Possible_Bit_Aligned_Component --
3387 ------------------------------------
3389 function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean is
3393 -- Case of indexed component
3395 when N_Indexed_Component =>
3397 P : constant Node_Id := Prefix (N);
3398 Ptyp : constant Entity_Id := Etype (P);
3401 -- If we know the component size and it is less than 64, then
3402 -- we are definitely OK. The back end always does assignment
3403 -- of misaligned small objects correctly.
3405 if Known_Static_Component_Size (Ptyp)
3406 and then Component_Size (Ptyp) <= 64
3410 -- Otherwise, we need to test the prefix, to see if we are
3411 -- indexing from a possibly unaligned component.
3414 return Possible_Bit_Aligned_Component (P);
3418 -- Case of selected component
3420 when N_Selected_Component =>
3422 P : constant Node_Id := Prefix (N);
3423 Comp : constant Entity_Id := Entity (Selector_Name (N));
3426 -- If there is no component clause, then we are in the clear
3427 -- since the back end will never misalign a large component
3428 -- unless it is forced to do so. In the clear means we need
3429 -- only the recursive test on the prefix.
3431 if Component_May_Be_Bit_Aligned (Comp) then
3434 return Possible_Bit_Aligned_Component (P);
3438 -- If we have neither a record nor array component, it means that
3439 -- we have fallen off the top testing prefixes recursively, and
3440 -- we now have a stand alone object, where we don't have a problem
3446 end Possible_Bit_Aligned_Component;