1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Debug; use Debug;
28 with Einfo; use Einfo;
29 with Errout; use Errout;
30 with Exp_Ch2; use Exp_Ch2;
31 with Exp_Ch4; use Exp_Ch4;
32 with Exp_Ch11; use Exp_Ch11;
33 with Exp_Pakd; use Exp_Pakd;
34 with Exp_Util; use Exp_Util;
35 with Elists; use Elists;
36 with Eval_Fat; use Eval_Fat;
37 with Freeze; use Freeze;
39 with Nlists; use Nlists;
40 with Nmake; use Nmake;
42 with Output; use Output;
43 with Restrict; use Restrict;
44 with Rident; use Rident;
45 with Rtsfind; use Rtsfind;
47 with Sem_Aux; use Sem_Aux;
48 with Sem_Eval; use Sem_Eval;
49 with Sem_Ch3; use Sem_Ch3;
50 with Sem_Ch8; use Sem_Ch8;
51 with Sem_Res; use Sem_Res;
52 with Sem_Util; use Sem_Util;
53 with Sem_Warn; use Sem_Warn;
54 with Sinfo; use Sinfo;
55 with Sinput; use Sinput;
56 with Snames; use Snames;
57 with Sprint; use Sprint;
58 with Stand; use Stand;
59 with Targparm; use Targparm;
60 with Tbuild; use Tbuild;
61 with Ttypes; use Ttypes;
62 with Urealp; use Urealp;
63 with Validsw; use Validsw;
65 package body Checks is
67 -- General note: many of these routines are concerned with generating
68 -- checking code to make sure that constraint error is raised at runtime.
69 -- Clearly this code is only needed if the expander is active, since
70 -- otherwise we will not be generating code or going into the runtime
73 -- We therefore disconnect most of these checks if the expander is
74 -- inactive. This has the additional benefit that we do not need to
75 -- worry about the tree being messed up by previous errors (since errors
76 -- turn off expansion anyway).
78 -- There are a few exceptions to the above rule. For instance routines
79 -- such as Apply_Scalar_Range_Check that do not insert any code can be
80 -- safely called even when the Expander is inactive (but Errors_Detected
81 -- is 0). The benefit of executing this code when expansion is off, is
82 -- the ability to emit constraint error warning for static expressions
83 -- even when we are not generating code.
85 -------------------------------------
86 -- Suppression of Redundant Checks --
87 -------------------------------------
89 -- This unit implements a limited circuit for removal of redundant
90 -- checks. The processing is based on a tracing of simple sequential
91 -- flow. For any sequence of statements, we save expressions that are
92 -- marked to be checked, and then if the same expression appears later
93 -- with the same check, then under certain circumstances, the second
94 -- check can be suppressed.
96 -- Basically, we can suppress the check if we know for certain that
97 -- the previous expression has been elaborated (together with its
98 -- check), and we know that the exception frame is the same, and that
99 -- nothing has happened to change the result of the exception.
101 -- Let us examine each of these three conditions in turn to describe
102 -- how we ensure that this condition is met.
104 -- First, we need to know for certain that the previous expression has
105 -- been executed. This is done principly by the mechanism of calling
106 -- Conditional_Statements_Begin at the start of any statement sequence
107 -- and Conditional_Statements_End at the end. The End call causes all
108 -- checks remembered since the Begin call to be discarded. This does
109 -- miss a few cases, notably the case of a nested BEGIN-END block with
110 -- no exception handlers. But the important thing is to be conservative.
111 -- The other protection is that all checks are discarded if a label
112 -- is encountered, since then the assumption of sequential execution
113 -- is violated, and we don't know enough about the flow.
115 -- Second, we need to know that the exception frame is the same. We
116 -- do this by killing all remembered checks when we enter a new frame.
117 -- Again, that's over-conservative, but generally the cases we can help
118 -- with are pretty local anyway (like the body of a loop for example).
120 -- Third, we must be sure to forget any checks which are no longer valid.
121 -- This is done by two mechanisms, first the Kill_Checks_Variable call is
122 -- used to note any changes to local variables. We only attempt to deal
123 -- with checks involving local variables, so we do not need to worry
124 -- about global variables. Second, a call to any non-global procedure
125 -- causes us to abandon all stored checks, since such a all may affect
126 -- the values of any local variables.
128 -- The following define the data structures used to deal with remembering
129 -- checks so that redundant checks can be eliminated as described above.
131 -- Right now, the only expressions that we deal with are of the form of
132 -- simple local objects (either declared locally, or IN parameters) or
133 -- such objects plus/minus a compile time known constant. We can do
134 -- more later on if it seems worthwhile, but this catches many simple
135 -- cases in practice.
137 -- The following record type reflects a single saved check. An entry
138 -- is made in the stack of saved checks if and only if the expression
139 -- has been elaborated with the indicated checks.
141 type Saved_Check is record
143 -- Set True if entry is killed by Kill_Checks
146 -- The entity involved in the expression that is checked
149 -- A compile time value indicating the result of adding or
150 -- subtracting a compile time value. This value is to be
151 -- added to the value of the Entity. A value of zero is
152 -- used for the case of a simple entity reference.
154 Check_Type : Character;
155 -- This is set to 'R' for a range check (in which case Target_Type
156 -- is set to the target type for the range check) or to 'O' for an
157 -- overflow check (in which case Target_Type is set to Empty).
159 Target_Type : Entity_Id;
160 -- Used only if Do_Range_Check is set. Records the target type for
161 -- the check. We need this, because a check is a duplicate only if
162 -- it has a the same target type (or more accurately one with a
163 -- range that is smaller or equal to the stored target type of a
167 -- The following table keeps track of saved checks. Rather than use an
168 -- extensible table. We just use a table of fixed size, and we discard
169 -- any saved checks that do not fit. That's very unlikely to happen and
170 -- this is only an optimization in any case.
172 Saved_Checks : array (Int range 1 .. 200) of Saved_Check;
173 -- Array of saved checks
175 Num_Saved_Checks : Nat := 0;
176 -- Number of saved checks
178 -- The following stack keeps track of statement ranges. It is treated
179 -- as a stack. When Conditional_Statements_Begin is called, an entry
180 -- is pushed onto this stack containing the value of Num_Saved_Checks
181 -- at the time of the call. Then when Conditional_Statements_End is
182 -- called, this value is popped off and used to reset Num_Saved_Checks.
184 -- Note: again, this is a fixed length stack with a size that should
185 -- always be fine. If the value of the stack pointer goes above the
186 -- limit, then we just forget all saved checks.
188 Saved_Checks_Stack : array (Int range 1 .. 100) of Nat;
189 Saved_Checks_TOS : Nat := 0;
191 -----------------------
192 -- Local Subprograms --
193 -----------------------
195 procedure Apply_Float_Conversion_Check
197 Target_Typ : Entity_Id);
198 -- The checks on a conversion from a floating-point type to an integer
199 -- type are delicate. They have to be performed before conversion, they
200 -- have to raise an exception when the operand is a NaN, and rounding must
201 -- be taken into account to determine the safe bounds of the operand.
203 procedure Apply_Selected_Length_Checks
205 Target_Typ : Entity_Id;
206 Source_Typ : Entity_Id;
207 Do_Static : Boolean);
208 -- This is the subprogram that does all the work for Apply_Length_Check
209 -- and Apply_Static_Length_Check. Expr, Target_Typ and Source_Typ are as
210 -- described for the above routines. The Do_Static flag indicates that
211 -- only a static check is to be done.
213 procedure Apply_Selected_Range_Checks
215 Target_Typ : Entity_Id;
216 Source_Typ : Entity_Id;
217 Do_Static : Boolean);
218 -- This is the subprogram that does all the work for Apply_Range_Check.
219 -- Expr, Target_Typ and Source_Typ are as described for the above
220 -- routine. The Do_Static flag indicates that only a static check is
223 type Check_Type is new Check_Id range Access_Check .. Division_Check;
224 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean;
225 -- This function is used to see if an access or division by zero check is
226 -- needed. The check is to be applied to a single variable appearing in the
227 -- source, and N is the node for the reference. If N is not of this form,
228 -- True is returned with no further processing. If N is of the right form,
229 -- then further processing determines if the given Check is needed.
231 -- The particular circuit is to see if we have the case of a check that is
232 -- not needed because it appears in the right operand of a short circuited
233 -- conditional where the left operand guards the check. For example:
235 -- if Var = 0 or else Q / Var > 12 then
239 -- In this example, the division check is not required. At the same time
240 -- we can issue warnings for suspicious use of non-short-circuited forms,
243 -- if Var = 0 or Q / Var > 12 then
249 Check_Type : Character;
250 Target_Type : Entity_Id;
251 Entry_OK : out Boolean;
255 -- This routine is used by Enable_Range_Check and Enable_Overflow_Check
256 -- to see if a check is of the form for optimization, and if so, to see
257 -- if it has already been performed. Expr is the expression to check,
258 -- and Check_Type is 'R' for a range check, 'O' for an overflow check.
259 -- Target_Type is the target type for a range check, and Empty for an
260 -- overflow check. If the entry is not of the form for optimization,
261 -- then Entry_OK is set to False, and the remaining out parameters
262 -- are undefined. If the entry is OK, then Ent/Ofs are set to the
263 -- entity and offset from the expression. Check_Num is the number of
264 -- a matching saved entry in Saved_Checks, or zero if no such entry
267 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id;
268 -- If a discriminal is used in constraining a prival, Return reference
269 -- to the discriminal of the protected body (which renames the parameter
270 -- of the enclosing protected operation). This clumsy transformation is
271 -- needed because privals are created too late and their actual subtypes
272 -- are not available when analysing the bodies of the protected operations.
273 -- This function is called whenever the bound is an entity and the scope
274 -- indicates a protected operation. If the bound is an in-parameter of
275 -- a protected operation that is not a prival, the function returns the
277 -- To be cleaned up???
279 function Guard_Access
282 Ck_Node : Node_Id) return Node_Id;
283 -- In the access type case, guard the test with a test to ensure
284 -- that the access value is non-null, since the checks do not
285 -- not apply to null access values.
287 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr);
288 -- Called by Apply_{Length,Range}_Checks to rewrite the tree with the
289 -- Constraint_Error node.
291 function Range_Or_Validity_Checks_Suppressed
292 (Expr : Node_Id) return Boolean;
293 -- Returns True if either range or validity checks or both are suppressed
294 -- for the type of the given expression, or, if the expression is the name
295 -- of an entity, if these checks are suppressed for the entity.
297 function Selected_Length_Checks
299 Target_Typ : Entity_Id;
300 Source_Typ : Entity_Id;
301 Warn_Node : Node_Id) return Check_Result;
302 -- Like Apply_Selected_Length_Checks, except it doesn't modify
303 -- anything, just returns a list of nodes as described in the spec of
304 -- this package for the Range_Check function.
306 function Selected_Range_Checks
308 Target_Typ : Entity_Id;
309 Source_Typ : Entity_Id;
310 Warn_Node : Node_Id) return Check_Result;
311 -- Like Apply_Selected_Range_Checks, except it doesn't modify anything,
312 -- just returns a list of nodes as described in the spec of this package
313 -- for the Range_Check function.
315 ------------------------------
316 -- Access_Checks_Suppressed --
317 ------------------------------
319 function Access_Checks_Suppressed (E : Entity_Id) return Boolean is
321 if Present (E) and then Checks_May_Be_Suppressed (E) then
322 return Is_Check_Suppressed (E, Access_Check);
324 return Scope_Suppress (Access_Check);
326 end Access_Checks_Suppressed;
328 -------------------------------------
329 -- Accessibility_Checks_Suppressed --
330 -------------------------------------
332 function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean is
334 if Present (E) and then Checks_May_Be_Suppressed (E) then
335 return Is_Check_Suppressed (E, Accessibility_Check);
337 return Scope_Suppress (Accessibility_Check);
339 end Accessibility_Checks_Suppressed;
341 -----------------------------
342 -- Activate_Division_Check --
343 -----------------------------
345 procedure Activate_Division_Check (N : Node_Id) is
347 Set_Do_Division_Check (N, True);
348 Possible_Local_Raise (N, Standard_Constraint_Error);
349 end Activate_Division_Check;
351 -----------------------------
352 -- Activate_Overflow_Check --
353 -----------------------------
355 procedure Activate_Overflow_Check (N : Node_Id) is
357 Set_Do_Overflow_Check (N, True);
358 Possible_Local_Raise (N, Standard_Constraint_Error);
359 end Activate_Overflow_Check;
361 --------------------------
362 -- Activate_Range_Check --
363 --------------------------
365 procedure Activate_Range_Check (N : Node_Id) is
367 Set_Do_Range_Check (N, True);
368 Possible_Local_Raise (N, Standard_Constraint_Error);
369 end Activate_Range_Check;
371 ---------------------------------
372 -- Alignment_Checks_Suppressed --
373 ---------------------------------
375 function Alignment_Checks_Suppressed (E : Entity_Id) return Boolean is
377 if Present (E) and then Checks_May_Be_Suppressed (E) then
378 return Is_Check_Suppressed (E, Alignment_Check);
380 return Scope_Suppress (Alignment_Check);
382 end Alignment_Checks_Suppressed;
384 -------------------------
385 -- Append_Range_Checks --
386 -------------------------
388 procedure Append_Range_Checks
389 (Checks : Check_Result;
391 Suppress_Typ : Entity_Id;
392 Static_Sloc : Source_Ptr;
395 Internal_Flag_Node : constant Node_Id := Flag_Node;
396 Internal_Static_Sloc : constant Source_Ptr := Static_Sloc;
398 Checks_On : constant Boolean :=
399 (not Index_Checks_Suppressed (Suppress_Typ))
401 (not Range_Checks_Suppressed (Suppress_Typ));
404 -- For now we just return if Checks_On is false, however this should
405 -- be enhanced to check for an always True value in the condition
406 -- and to generate a compilation warning???
408 if not Checks_On then
413 exit when No (Checks (J));
415 if Nkind (Checks (J)) = N_Raise_Constraint_Error
416 and then Present (Condition (Checks (J)))
418 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
419 Append_To (Stmts, Checks (J));
420 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
426 Make_Raise_Constraint_Error (Internal_Static_Sloc,
427 Reason => CE_Range_Check_Failed));
430 end Append_Range_Checks;
432 ------------------------
433 -- Apply_Access_Check --
434 ------------------------
436 procedure Apply_Access_Check (N : Node_Id) is
437 P : constant Node_Id := Prefix (N);
440 -- We do not need checks if we are not generating code (i.e. the
441 -- expander is not active). This is not just an optimization, there
442 -- are cases (e.g. with pragma Debug) where generating the checks
443 -- can cause real trouble).
445 if not Expander_Active then
449 -- No check if short circuiting makes check unnecessary
451 if not Check_Needed (P, Access_Check) then
455 -- No check if accessing the Offset_To_Top component of a dispatch
456 -- table. They are safe by construction.
458 if Tagged_Type_Expansion
459 and then Present (Etype (P))
460 and then RTU_Loaded (Ada_Tags)
461 and then RTE_Available (RE_Offset_To_Top_Ptr)
462 and then Etype (P) = RTE (RE_Offset_To_Top_Ptr)
467 -- Otherwise go ahead and install the check
469 Install_Null_Excluding_Check (P);
470 end Apply_Access_Check;
472 -------------------------------
473 -- Apply_Accessibility_Check --
474 -------------------------------
476 procedure Apply_Accessibility_Check
479 Insert_Node : Node_Id)
481 Loc : constant Source_Ptr := Sloc (N);
482 Param_Ent : constant Entity_Id := Param_Entity (N);
483 Param_Level : Node_Id;
484 Type_Level : Node_Id;
487 if Inside_A_Generic then
490 -- Only apply the run-time check if the access parameter has an
491 -- associated extra access level parameter and when the level of the
492 -- type is less deep than the level of the access parameter, and
493 -- accessibility checks are not suppressed.
495 elsif Present (Param_Ent)
496 and then Present (Extra_Accessibility (Param_Ent))
497 and then UI_Gt (Object_Access_Level (N), Type_Access_Level (Typ))
498 and then not Accessibility_Checks_Suppressed (Param_Ent)
499 and then not Accessibility_Checks_Suppressed (Typ)
502 New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc);
505 Make_Integer_Literal (Loc, Type_Access_Level (Typ));
507 -- Raise Program_Error if the accessibility level of the access
508 -- parameter is deeper than the level of the target access type.
510 Insert_Action (Insert_Node,
511 Make_Raise_Program_Error (Loc,
514 Left_Opnd => Param_Level,
515 Right_Opnd => Type_Level),
516 Reason => PE_Accessibility_Check_Failed));
518 Analyze_And_Resolve (N);
520 end Apply_Accessibility_Check;
522 --------------------------------
523 -- Apply_Address_Clause_Check --
524 --------------------------------
526 procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is
527 AC : constant Node_Id := Address_Clause (E);
528 Loc : constant Source_Ptr := Sloc (AC);
529 Typ : constant Entity_Id := Etype (E);
530 Aexp : constant Node_Id := Expression (AC);
533 -- Address expression (not necessarily the same as Aexp, for example
534 -- when Aexp is a reference to a constant, in which case Expr gets
535 -- reset to reference the value expression of the constant.
537 procedure Compile_Time_Bad_Alignment;
538 -- Post error warnings when alignment is known to be incompatible. Note
539 -- that we do not go as far as inserting a raise of Program_Error since
540 -- this is an erroneous case, and it may happen that we are lucky and an
541 -- underaligned address turns out to be OK after all.
543 --------------------------------
544 -- Compile_Time_Bad_Alignment --
545 --------------------------------
547 procedure Compile_Time_Bad_Alignment is
549 if Address_Clause_Overlay_Warnings then
551 ("?specified address for& may be inconsistent with alignment ",
554 ("\?program execution may be erroneous (RM 13.3(27))",
556 Set_Address_Warning_Posted (AC);
558 end Compile_Time_Bad_Alignment;
560 -- Start of processing for Apply_Address_Clause_Check
563 -- See if alignment check needed. Note that we never need a check if the
564 -- maximum alignment is one, since the check will always succeed.
566 -- Note: we do not check for checks suppressed here, since that check
567 -- was done in Sem_Ch13 when the address clause was processed. We are
568 -- only called if checks were not suppressed. The reason for this is
569 -- that we have to delay the call to Apply_Alignment_Check till freeze
570 -- time (so that all types etc are elaborated), but we have to check
571 -- the status of check suppressing at the point of the address clause.
574 or else not Check_Address_Alignment (AC)
575 or else Maximum_Alignment = 1
580 -- Obtain expression from address clause
582 Expr := Expression (AC);
584 -- The following loop digs for the real expression to use in the check
587 -- For constant, get constant expression
589 if Is_Entity_Name (Expr)
590 and then Ekind (Entity (Expr)) = E_Constant
592 Expr := Constant_Value (Entity (Expr));
594 -- For unchecked conversion, get result to convert
596 elsif Nkind (Expr) = N_Unchecked_Type_Conversion then
597 Expr := Expression (Expr);
599 -- For (common case) of To_Address call, get argument
601 elsif Nkind (Expr) = N_Function_Call
602 and then Is_Entity_Name (Name (Expr))
603 and then Is_RTE (Entity (Name (Expr)), RE_To_Address)
605 Expr := First (Parameter_Associations (Expr));
607 if Nkind (Expr) = N_Parameter_Association then
608 Expr := Explicit_Actual_Parameter (Expr);
611 -- We finally have the real expression
618 -- See if we know that Expr has a bad alignment at compile time
620 if Compile_Time_Known_Value (Expr)
621 and then (Known_Alignment (E) or else Known_Alignment (Typ))
624 AL : Uint := Alignment (Typ);
627 -- The object alignment might be more restrictive than the
630 if Known_Alignment (E) then
634 if Expr_Value (Expr) mod AL /= 0 then
635 Compile_Time_Bad_Alignment;
641 -- If the expression has the form X'Address, then we can find out if
642 -- the object X has an alignment that is compatible with the object E.
643 -- If it hasn't or we don't know, we defer issuing the warning until
644 -- the end of the compilation to take into account back end annotations.
646 elsif Nkind (Expr) = N_Attribute_Reference
647 and then Attribute_Name (Expr) = Name_Address
648 and then Has_Compatible_Alignment (E, Prefix (Expr)) = Known_Compatible
653 -- Here we do not know if the value is acceptable. Stricly we don't have
654 -- to do anything, since if the alignment is bad, we have an erroneous
655 -- program. However we are allowed to check for erroneous conditions and
656 -- we decide to do this by default if the check is not suppressed.
658 -- However, don't do the check if elaboration code is unwanted
660 if Restriction_Active (No_Elaboration_Code) then
663 -- Generate a check to raise PE if alignment may be inappropriate
666 -- If the original expression is a non-static constant, use the
667 -- name of the constant itself rather than duplicating its
668 -- defining expression, which was extracted above.
670 -- Note: Expr is empty if the address-clause is applied to in-mode
671 -- actuals (allowed by 13.1(22)).
673 if not Present (Expr)
675 (Is_Entity_Name (Expression (AC))
676 and then Ekind (Entity (Expression (AC))) = E_Constant
677 and then Nkind (Parent (Entity (Expression (AC))))
678 = N_Object_Declaration)
680 Expr := New_Copy_Tree (Expression (AC));
682 Remove_Side_Effects (Expr);
685 Insert_After_And_Analyze (N,
686 Make_Raise_Program_Error (Loc,
693 (RTE (RE_Integer_Address), Expr),
695 Make_Attribute_Reference (Loc,
696 Prefix => New_Occurrence_Of (E, Loc),
697 Attribute_Name => Name_Alignment)),
698 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
699 Reason => PE_Misaligned_Address_Value),
700 Suppress => All_Checks);
705 -- If we have some missing run time component in configurable run time
706 -- mode then just skip the check (it is not required in any case).
708 when RE_Not_Available =>
710 end Apply_Address_Clause_Check;
712 -------------------------------------
713 -- Apply_Arithmetic_Overflow_Check --
714 -------------------------------------
716 -- This routine is called only if the type is an integer type, and a
717 -- software arithmetic overflow check may be needed for op (add, subtract,
718 -- or multiply). This check is performed only if Software_Overflow_Checking
719 -- is enabled and Do_Overflow_Check is set. In this case we expand the
720 -- operation into a more complex sequence of tests that ensures that
721 -- overflow is properly caught.
723 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
724 Loc : constant Source_Ptr := Sloc (N);
725 Typ : Entity_Id := Etype (N);
726 Rtyp : Entity_Id := Root_Type (Typ);
729 -- An interesting special case. If the arithmetic operation appears as
730 -- the operand of a type conversion:
734 -- and all the following conditions apply:
736 -- arithmetic operation is for a signed integer type
737 -- target type type1 is a static integer subtype
738 -- range of x and y are both included in the range of type1
739 -- range of x op y is included in the range of type1
740 -- size of type1 is at least twice the result size of op
742 -- then we don't do an overflow check in any case, instead we transform
743 -- the operation so that we end up with:
745 -- type1 (type1 (x) op type1 (y))
747 -- This avoids intermediate overflow before the conversion. It is
748 -- explicitly permitted by RM 3.5.4(24):
750 -- For the execution of a predefined operation of a signed integer
751 -- type, the implementation need not raise Constraint_Error if the
752 -- result is outside the base range of the type, so long as the
753 -- correct result is produced.
755 -- It's hard to imagine that any programmer counts on the exception
756 -- being raised in this case, and in any case it's wrong coding to
757 -- have this expectation, given the RM permission. Furthermore, other
758 -- Ada compilers do allow such out of range results.
760 -- Note that we do this transformation even if overflow checking is
761 -- off, since this is precisely about giving the "right" result and
762 -- avoiding the need for an overflow check.
764 -- Note: this circuit is partially redundant with respect to the similar
765 -- processing in Exp_Ch4.Expand_N_Type_Conversion, but the latter deals
766 -- with cases that do not come through here. We still need the following
767 -- processing even with the Exp_Ch4 code in place, since we want to be
768 -- sure not to generate the arithmetic overflow check in these cases
769 -- (Exp_Ch4 would have a hard time removing them once generated).
771 if Is_Signed_Integer_Type (Typ)
772 and then Nkind (Parent (N)) = N_Type_Conversion
775 Target_Type : constant Entity_Id :=
776 Base_Type (Entity (Subtype_Mark (Parent (N))));
790 if Is_Integer_Type (Target_Type)
791 and then RM_Size (Root_Type (Target_Type)) >= 2 * RM_Size (Rtyp)
793 Tlo := Expr_Value (Type_Low_Bound (Target_Type));
794 Thi := Expr_Value (Type_High_Bound (Target_Type));
797 (Left_Opnd (N), LOK, Llo, Lhi, Assume_Valid => True);
799 (Right_Opnd (N), ROK, Rlo, Rhi, Assume_Valid => True);
802 and then Tlo <= Llo and then Lhi <= Thi
803 and then Tlo <= Rlo and then Rhi <= Thi
805 Determine_Range (N, VOK, Vlo, Vhi, Assume_Valid => True);
807 if VOK and then Tlo <= Vlo and then Vhi <= Thi then
808 Rewrite (Left_Opnd (N),
809 Make_Type_Conversion (Loc,
810 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
811 Expression => Relocate_Node (Left_Opnd (N))));
813 Rewrite (Right_Opnd (N),
814 Make_Type_Conversion (Loc,
815 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
816 Expression => Relocate_Node (Right_Opnd (N))));
818 Set_Etype (N, Target_Type);
820 Rtyp := Root_Type (Typ);
821 Analyze_And_Resolve (Left_Opnd (N), Target_Type);
822 Analyze_And_Resolve (Right_Opnd (N), Target_Type);
824 -- Given that the target type is twice the size of the
825 -- source type, overflow is now impossible, so we can
826 -- safely kill the overflow check and return.
828 Set_Do_Overflow_Check (N, False);
836 -- Now see if an overflow check is required
839 Siz : constant Int := UI_To_Int (Esize (Rtyp));
840 Dsiz : constant Int := Siz * 2;
847 -- Skip check if back end does overflow checks, or the overflow flag
848 -- is not set anyway, or we are not doing code expansion, or the
849 -- parent node is a type conversion whose operand is an arithmetic
850 -- operation on signed integers on which the expander can promote
851 -- later the operands to type Integer (see Expand_N_Type_Conversion).
853 -- Special case CLI target, where arithmetic overflow checks can be
854 -- performed for integer and long_integer
856 if Backend_Overflow_Checks_On_Target
857 or else not Do_Overflow_Check (N)
858 or else not Expander_Active
859 or else (Present (Parent (N))
860 and then Nkind (Parent (N)) = N_Type_Conversion
861 and then Integer_Promotion_Possible (Parent (N)))
863 (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
868 -- Otherwise, generate the full general code for front end overflow
869 -- detection, which works by doing arithmetic in a larger type:
875 -- Typ (Checktyp (x) op Checktyp (y));
877 -- where Typ is the type of the original expression, and Checktyp is
878 -- an integer type of sufficient length to hold the largest possible
881 -- If the size of check type exceeds the size of Long_Long_Integer,
882 -- we use a different approach, expanding to:
884 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
886 -- where xxx is Add, Multiply or Subtract as appropriate
888 -- Find check type if one exists
890 if Dsiz <= Standard_Integer_Size then
891 Ctyp := Standard_Integer;
893 elsif Dsiz <= Standard_Long_Long_Integer_Size then
894 Ctyp := Standard_Long_Long_Integer;
896 -- No check type exists, use runtime call
899 if Nkind (N) = N_Op_Add then
900 Cent := RE_Add_With_Ovflo_Check;
902 elsif Nkind (N) = N_Op_Multiply then
903 Cent := RE_Multiply_With_Ovflo_Check;
906 pragma Assert (Nkind (N) = N_Op_Subtract);
907 Cent := RE_Subtract_With_Ovflo_Check;
912 Make_Function_Call (Loc,
913 Name => New_Reference_To (RTE (Cent), Loc),
914 Parameter_Associations => New_List (
915 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
916 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
918 Analyze_And_Resolve (N, Typ);
922 -- If we fall through, we have the case where we do the arithmetic
923 -- in the next higher type and get the check by conversion. In these
924 -- cases Ctyp is set to the type to be used as the check type.
926 Opnod := Relocate_Node (N);
928 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
931 Set_Etype (Opnd, Ctyp);
932 Set_Analyzed (Opnd, True);
933 Set_Left_Opnd (Opnod, Opnd);
935 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
938 Set_Etype (Opnd, Ctyp);
939 Set_Analyzed (Opnd, True);
940 Set_Right_Opnd (Opnod, Opnd);
942 -- The type of the operation changes to the base type of the check
943 -- type, and we reset the overflow check indication, since clearly no
944 -- overflow is possible now that we are using a double length type.
945 -- We also set the Analyzed flag to avoid a recursive attempt to
948 Set_Etype (Opnod, Base_Type (Ctyp));
949 Set_Do_Overflow_Check (Opnod, False);
950 Set_Analyzed (Opnod, True);
952 -- Now build the outer conversion
954 Opnd := OK_Convert_To (Typ, Opnod);
956 Set_Etype (Opnd, Typ);
958 -- In the discrete type case, we directly generate the range check
959 -- for the outer operand. This range check will implement the
960 -- required overflow check.
962 if Is_Discrete_Type (Typ) then
965 (Expression (N), Typ, CE_Overflow_Check_Failed);
967 -- For other types, we enable overflow checking on the conversion,
968 -- after setting the node as analyzed to prevent recursive attempts
969 -- to expand the conversion node.
972 Set_Analyzed (Opnd, True);
973 Enable_Overflow_Check (Opnd);
978 when RE_Not_Available =>
981 end Apply_Arithmetic_Overflow_Check;
983 ----------------------------
984 -- Apply_Constraint_Check --
985 ----------------------------
987 procedure Apply_Constraint_Check
990 No_Sliding : Boolean := False)
992 Desig_Typ : Entity_Id;
995 if Inside_A_Generic then
998 elsif Is_Scalar_Type (Typ) then
999 Apply_Scalar_Range_Check (N, Typ);
1001 elsif Is_Array_Type (Typ) then
1003 -- A useful optimization: an aggregate with only an others clause
1004 -- always has the right bounds.
1006 if Nkind (N) = N_Aggregate
1007 and then No (Expressions (N))
1009 (First (Choices (First (Component_Associations (N)))))
1015 if Is_Constrained (Typ) then
1016 Apply_Length_Check (N, Typ);
1019 Apply_Range_Check (N, Typ);
1022 Apply_Range_Check (N, Typ);
1025 elsif (Is_Record_Type (Typ)
1026 or else Is_Private_Type (Typ))
1027 and then Has_Discriminants (Base_Type (Typ))
1028 and then Is_Constrained (Typ)
1030 Apply_Discriminant_Check (N, Typ);
1032 elsif Is_Access_Type (Typ) then
1034 Desig_Typ := Designated_Type (Typ);
1036 -- No checks necessary if expression statically null
1038 if Known_Null (N) then
1039 if Can_Never_Be_Null (Typ) then
1040 Install_Null_Excluding_Check (N);
1043 -- No sliding possible on access to arrays
1045 elsif Is_Array_Type (Desig_Typ) then
1046 if Is_Constrained (Desig_Typ) then
1047 Apply_Length_Check (N, Typ);
1050 Apply_Range_Check (N, Typ);
1052 elsif Has_Discriminants (Base_Type (Desig_Typ))
1053 and then Is_Constrained (Desig_Typ)
1055 Apply_Discriminant_Check (N, Typ);
1058 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1059 -- this check if the constraint node is illegal, as shown by having
1060 -- an error posted. This additional guard prevents cascaded errors
1061 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1063 if Can_Never_Be_Null (Typ)
1064 and then not Can_Never_Be_Null (Etype (N))
1065 and then not Error_Posted (N)
1067 Install_Null_Excluding_Check (N);
1070 end Apply_Constraint_Check;
1072 ------------------------------
1073 -- Apply_Discriminant_Check --
1074 ------------------------------
1076 procedure Apply_Discriminant_Check
1079 Lhs : Node_Id := Empty)
1081 Loc : constant Source_Ptr := Sloc (N);
1082 Do_Access : constant Boolean := Is_Access_Type (Typ);
1083 S_Typ : Entity_Id := Etype (N);
1087 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean;
1088 -- A heap object with an indefinite subtype is constrained by its
1089 -- initial value, and assigning to it requires a constraint_check.
1090 -- The target may be an explicit dereference, or a renaming of one.
1092 function Is_Aliased_Unconstrained_Component return Boolean;
1093 -- It is possible for an aliased component to have a nominal
1094 -- unconstrained subtype (through instantiation). If this is a
1095 -- discriminated component assigned in the expansion of an aggregate
1096 -- in an initialization, the check must be suppressed. This unusual
1097 -- situation requires a predicate of its own.
1099 ----------------------------------
1100 -- Denotes_Explicit_Dereference --
1101 ----------------------------------
1103 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean is
1106 Nkind (Obj) = N_Explicit_Dereference
1108 (Is_Entity_Name (Obj)
1109 and then Present (Renamed_Object (Entity (Obj)))
1110 and then Nkind (Renamed_Object (Entity (Obj)))
1111 = N_Explicit_Dereference);
1112 end Denotes_Explicit_Dereference;
1114 ----------------------------------------
1115 -- Is_Aliased_Unconstrained_Component --
1116 ----------------------------------------
1118 function Is_Aliased_Unconstrained_Component return Boolean is
1123 if Nkind (Lhs) /= N_Selected_Component then
1126 Comp := Entity (Selector_Name (Lhs));
1127 Pref := Prefix (Lhs);
1130 if Ekind (Comp) /= E_Component
1131 or else not Is_Aliased (Comp)
1136 return not Comes_From_Source (Pref)
1137 and then In_Instance
1138 and then not Is_Constrained (Etype (Comp));
1139 end Is_Aliased_Unconstrained_Component;
1141 -- Start of processing for Apply_Discriminant_Check
1145 T_Typ := Designated_Type (Typ);
1150 -- Nothing to do if discriminant checks are suppressed or else no code
1151 -- is to be generated
1153 if not Expander_Active
1154 or else Discriminant_Checks_Suppressed (T_Typ)
1159 -- No discriminant checks necessary for an access when expression is
1160 -- statically Null. This is not only an optimization, it is fundamental
1161 -- because otherwise discriminant checks may be generated in init procs
1162 -- for types containing an access to a not-yet-frozen record, causing a
1163 -- deadly forward reference.
1165 -- Also, if the expression is of an access type whose designated type is
1166 -- incomplete, then the access value must be null and we suppress the
1169 if Known_Null (N) then
1172 elsif Is_Access_Type (S_Typ) then
1173 S_Typ := Designated_Type (S_Typ);
1175 if Ekind (S_Typ) = E_Incomplete_Type then
1180 -- If an assignment target is present, then we need to generate the
1181 -- actual subtype if the target is a parameter or aliased object with
1182 -- an unconstrained nominal subtype.
1184 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1185 -- subtype to the parameter and dereference cases, since other aliased
1186 -- objects are unconstrained (unless the nominal subtype is explicitly
1190 and then (Present (Param_Entity (Lhs))
1191 or else (Ada_Version < Ada_05
1192 and then not Is_Constrained (T_Typ)
1193 and then Is_Aliased_View (Lhs)
1194 and then not Is_Aliased_Unconstrained_Component)
1195 or else (Ada_Version >= Ada_05
1196 and then not Is_Constrained (T_Typ)
1197 and then Denotes_Explicit_Dereference (Lhs)
1198 and then Nkind (Original_Node (Lhs)) /=
1201 T_Typ := Get_Actual_Subtype (Lhs);
1204 -- Nothing to do if the type is unconstrained (this is the case where
1205 -- the actual subtype in the RM sense of N is unconstrained and no check
1208 if not Is_Constrained (T_Typ) then
1211 -- Ada 2005: nothing to do if the type is one for which there is a
1212 -- partial view that is constrained.
1214 elsif Ada_Version >= Ada_05
1215 and then Has_Constrained_Partial_View (Base_Type (T_Typ))
1220 -- Nothing to do if the type is an Unchecked_Union
1222 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1226 -- Suppress checks if the subtypes are the same. the check must be
1227 -- preserved in an assignment to a formal, because the constraint is
1228 -- given by the actual.
1230 if Nkind (Original_Node (N)) /= N_Allocator
1232 or else not Is_Entity_Name (Lhs)
1233 or else No (Param_Entity (Lhs)))
1236 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1237 and then not Is_Aliased_View (Lhs)
1242 -- We can also eliminate checks on allocators with a subtype mark that
1243 -- coincides with the context type. The context type may be a subtype
1244 -- without a constraint (common case, a generic actual).
1246 elsif Nkind (Original_Node (N)) = N_Allocator
1247 and then Is_Entity_Name (Expression (Original_Node (N)))
1250 Alloc_Typ : constant Entity_Id :=
1251 Entity (Expression (Original_Node (N)));
1254 if Alloc_Typ = T_Typ
1255 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1256 and then Is_Entity_Name (
1257 Subtype_Indication (Parent (T_Typ)))
1258 and then Alloc_Typ = Base_Type (T_Typ))
1266 -- See if we have a case where the types are both constrained, and all
1267 -- the constraints are constants. In this case, we can do the check
1268 -- successfully at compile time.
1270 -- We skip this check for the case where the node is a rewritten`
1271 -- allocator, because it already carries the context subtype, and
1272 -- extracting the discriminants from the aggregate is messy.
1274 if Is_Constrained (S_Typ)
1275 and then Nkind (Original_Node (N)) /= N_Allocator
1285 -- S_Typ may not have discriminants in the case where it is a
1286 -- private type completed by a default discriminated type. In that
1287 -- case, we need to get the constraints from the underlying_type.
1288 -- If the underlying type is unconstrained (i.e. has no default
1289 -- discriminants) no check is needed.
1291 if Has_Discriminants (S_Typ) then
1292 Discr := First_Discriminant (S_Typ);
1293 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1296 Discr := First_Discriminant (Underlying_Type (S_Typ));
1299 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1305 -- A further optimization: if T_Typ is derived from S_Typ
1306 -- without imposing a constraint, no check is needed.
1308 if Nkind (Original_Node (Parent (T_Typ))) =
1309 N_Full_Type_Declaration
1312 Type_Def : constant Node_Id :=
1314 (Original_Node (Parent (T_Typ)));
1316 if Nkind (Type_Def) = N_Derived_Type_Definition
1317 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1318 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1326 DconT := First_Elmt (Discriminant_Constraint (T_Typ));
1328 while Present (Discr) loop
1329 ItemS := Node (DconS);
1330 ItemT := Node (DconT);
1332 -- For a discriminated component type constrained by the
1333 -- current instance of an enclosing type, there is no
1334 -- applicable discriminant check.
1336 if Nkind (ItemT) = N_Attribute_Reference
1337 and then Is_Access_Type (Etype (ItemT))
1338 and then Is_Entity_Name (Prefix (ItemT))
1339 and then Is_Type (Entity (Prefix (ItemT)))
1344 -- If the expressions for the discriminants are identical
1345 -- and it is side-effect free (for now just an entity),
1346 -- this may be a shared constraint, e.g. from a subtype
1347 -- without a constraint introduced as a generic actual.
1348 -- Examine other discriminants if any.
1351 and then Is_Entity_Name (ItemS)
1355 elsif not Is_OK_Static_Expression (ItemS)
1356 or else not Is_OK_Static_Expression (ItemT)
1360 elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
1361 if Do_Access then -- needs run-time check.
1364 Apply_Compile_Time_Constraint_Error
1365 (N, "incorrect value for discriminant&?",
1366 CE_Discriminant_Check_Failed, Ent => Discr);
1373 Next_Discriminant (Discr);
1382 -- Here we need a discriminant check. First build the expression
1383 -- for the comparisons of the discriminants:
1385 -- (n.disc1 /= typ.disc1) or else
1386 -- (n.disc2 /= typ.disc2) or else
1388 -- (n.discn /= typ.discn)
1390 Cond := Build_Discriminant_Checks (N, T_Typ);
1392 -- If Lhs is set and is a parameter, then the condition is
1393 -- guarded by: lhs'constrained and then (condition built above)
1395 if Present (Param_Entity (Lhs)) then
1399 Make_Attribute_Reference (Loc,
1400 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1401 Attribute_Name => Name_Constrained),
1402 Right_Opnd => Cond);
1406 Cond := Guard_Access (Cond, Loc, N);
1410 Make_Raise_Constraint_Error (Loc,
1412 Reason => CE_Discriminant_Check_Failed));
1413 end Apply_Discriminant_Check;
1415 ------------------------
1416 -- Apply_Divide_Check --
1417 ------------------------
1419 procedure Apply_Divide_Check (N : Node_Id) is
1420 Loc : constant Source_Ptr := Sloc (N);
1421 Typ : constant Entity_Id := Etype (N);
1422 Left : constant Node_Id := Left_Opnd (N);
1423 Right : constant Node_Id := Right_Opnd (N);
1433 pragma Warnings (Off, Lhi);
1434 -- Don't actually use this value
1438 and then not Backend_Divide_Checks_On_Target
1439 and then Check_Needed (Right, Division_Check)
1441 Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True);
1443 -- See if division by zero possible, and if so generate test. This
1444 -- part of the test is not controlled by the -gnato switch.
1446 if Do_Division_Check (N) then
1447 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1449 Make_Raise_Constraint_Error (Loc,
1452 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1453 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1454 Reason => CE_Divide_By_Zero));
1458 -- Test for extremely annoying case of xxx'First divided by -1
1460 if Do_Overflow_Check (N) then
1461 if Nkind (N) = N_Op_Divide
1462 and then Is_Signed_Integer_Type (Typ)
1464 Determine_Range (Left, LOK, Llo, Lhi, Assume_Valid => True);
1465 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1467 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1469 ((not LOK) or else (Llo = LLB))
1472 Make_Raise_Constraint_Error (Loc,
1478 Duplicate_Subexpr_Move_Checks (Left),
1479 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1483 Duplicate_Subexpr (Right),
1485 Make_Integer_Literal (Loc, -1))),
1486 Reason => CE_Overflow_Check_Failed));
1491 end Apply_Divide_Check;
1493 ----------------------------------
1494 -- Apply_Float_Conversion_Check --
1495 ----------------------------------
1497 -- Let F and I be the source and target types of the conversion. The RM
1498 -- specifies that a floating-point value X is rounded to the nearest
1499 -- integer, with halfway cases being rounded away from zero. The rounded
1500 -- value of X is checked against I'Range.
1502 -- The catch in the above paragraph is that there is no good way to know
1503 -- whether the round-to-integer operation resulted in overflow. A remedy is
1504 -- to perform a range check in the floating-point domain instead, however:
1506 -- (1) The bounds may not be known at compile time
1507 -- (2) The check must take into account rounding or truncation.
1508 -- (3) The range of type I may not be exactly representable in F.
1509 -- (4) For the rounding case, The end-points I'First - 0.5 and
1510 -- I'Last + 0.5 may or may not be in range, depending on the
1511 -- sign of I'First and I'Last.
1512 -- (5) X may be a NaN, which will fail any comparison
1514 -- The following steps correctly convert X with rounding:
1516 -- (1) If either I'First or I'Last is not known at compile time, use
1517 -- I'Base instead of I in the next three steps and perform a
1518 -- regular range check against I'Range after conversion.
1519 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1520 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1521 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1522 -- In other words, take one of the closest floating-point numbers
1523 -- (which is an integer value) to I'First, and see if it is in
1525 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1526 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1527 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1528 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1529 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1531 -- For the truncating case, replace steps (2) and (3) as follows:
1532 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1533 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1535 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1536 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1539 procedure Apply_Float_Conversion_Check
1541 Target_Typ : Entity_Id)
1543 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1544 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1545 Loc : constant Source_Ptr := Sloc (Ck_Node);
1546 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1547 Target_Base : constant Entity_Id :=
1548 Implementation_Base_Type (Target_Typ);
1550 Par : constant Node_Id := Parent (Ck_Node);
1551 pragma Assert (Nkind (Par) = N_Type_Conversion);
1552 -- Parent of check node, must be a type conversion
1554 Truncate : constant Boolean := Float_Truncate (Par);
1555 Max_Bound : constant Uint :=
1557 (Machine_Radix (Expr_Type),
1558 Machine_Mantissa (Expr_Type) - 1) - 1;
1560 -- Largest bound, so bound plus or minus half is a machine number of F
1562 Ifirst, Ilast : Uint;
1563 -- Bounds of integer type
1566 -- Bounds to check in floating-point domain
1568 Lo_OK, Hi_OK : Boolean;
1569 -- True iff Lo resp. Hi belongs to I'Range
1571 Lo_Chk, Hi_Chk : Node_Id;
1572 -- Expressions that are False iff check fails
1574 Reason : RT_Exception_Code;
1577 if not Compile_Time_Known_Value (LB)
1578 or not Compile_Time_Known_Value (HB)
1581 -- First check that the value falls in the range of the base type,
1582 -- to prevent overflow during conversion and then perform a
1583 -- regular range check against the (dynamic) bounds.
1585 pragma Assert (Target_Base /= Target_Typ);
1587 Temp : constant Entity_Id :=
1588 Make_Defining_Identifier (Loc,
1589 Chars => New_Internal_Name ('T'));
1592 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1593 Set_Etype (Temp, Target_Base);
1595 Insert_Action (Parent (Par),
1596 Make_Object_Declaration (Loc,
1597 Defining_Identifier => Temp,
1598 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1599 Expression => New_Copy_Tree (Par)),
1600 Suppress => All_Checks);
1603 Make_Raise_Constraint_Error (Loc,
1606 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1607 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1608 Reason => CE_Range_Check_Failed));
1609 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
1615 -- Get the (static) bounds of the target type
1617 Ifirst := Expr_Value (LB);
1618 Ilast := Expr_Value (HB);
1620 -- A simple optimization: if the expression is a universal literal,
1621 -- we can do the comparison with the bounds and the conversion to
1622 -- an integer type statically. The range checks are unchanged.
1624 if Nkind (Ck_Node) = N_Real_Literal
1625 and then Etype (Ck_Node) = Universal_Real
1626 and then Is_Integer_Type (Target_Typ)
1627 and then Nkind (Parent (Ck_Node)) = N_Type_Conversion
1630 Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node));
1633 if Int_Val <= Ilast and then Int_Val >= Ifirst then
1635 -- Conversion is safe
1637 Rewrite (Parent (Ck_Node),
1638 Make_Integer_Literal (Loc, UI_To_Int (Int_Val)));
1639 Analyze_And_Resolve (Parent (Ck_Node), Target_Typ);
1645 -- Check against lower bound
1647 if Truncate and then Ifirst > 0 then
1648 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
1652 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
1655 elsif abs (Ifirst) < Max_Bound then
1656 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
1657 Lo_OK := (Ifirst > 0);
1660 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
1661 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
1666 -- Lo_Chk := (X >= Lo)
1668 Lo_Chk := Make_Op_Ge (Loc,
1669 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1670 Right_Opnd => Make_Real_Literal (Loc, Lo));
1673 -- Lo_Chk := (X > Lo)
1675 Lo_Chk := Make_Op_Gt (Loc,
1676 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1677 Right_Opnd => Make_Real_Literal (Loc, Lo));
1680 -- Check against higher bound
1682 if Truncate and then Ilast < 0 then
1683 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
1687 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
1690 elsif abs (Ilast) < Max_Bound then
1691 Hi := UR_From_Uint (Ilast) + Ureal_Half;
1692 Hi_OK := (Ilast < 0);
1694 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
1695 Hi_OK := (Hi <= UR_From_Uint (Ilast));
1700 -- Hi_Chk := (X <= Hi)
1702 Hi_Chk := Make_Op_Le (Loc,
1703 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1704 Right_Opnd => Make_Real_Literal (Loc, Hi));
1707 -- Hi_Chk := (X < Hi)
1709 Hi_Chk := Make_Op_Lt (Loc,
1710 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1711 Right_Opnd => Make_Real_Literal (Loc, Hi));
1714 -- If the bounds of the target type are the same as those of the base
1715 -- type, the check is an overflow check as a range check is not
1716 -- performed in these cases.
1718 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
1719 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
1721 Reason := CE_Overflow_Check_Failed;
1723 Reason := CE_Range_Check_Failed;
1726 -- Raise CE if either conditions does not hold
1728 Insert_Action (Ck_Node,
1729 Make_Raise_Constraint_Error (Loc,
1730 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
1732 end Apply_Float_Conversion_Check;
1734 ------------------------
1735 -- Apply_Length_Check --
1736 ------------------------
1738 procedure Apply_Length_Check
1740 Target_Typ : Entity_Id;
1741 Source_Typ : Entity_Id := Empty)
1744 Apply_Selected_Length_Checks
1745 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1746 end Apply_Length_Check;
1748 -----------------------
1749 -- Apply_Range_Check --
1750 -----------------------
1752 procedure Apply_Range_Check
1754 Target_Typ : Entity_Id;
1755 Source_Typ : Entity_Id := Empty)
1758 Apply_Selected_Range_Checks
1759 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1760 end Apply_Range_Check;
1762 ------------------------------
1763 -- Apply_Scalar_Range_Check --
1764 ------------------------------
1766 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
1767 -- off if it is already set on.
1769 procedure Apply_Scalar_Range_Check
1771 Target_Typ : Entity_Id;
1772 Source_Typ : Entity_Id := Empty;
1773 Fixed_Int : Boolean := False)
1775 Parnt : constant Node_Id := Parent (Expr);
1777 Arr : Node_Id := Empty; -- initialize to prevent warning
1778 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
1781 Is_Subscr_Ref : Boolean;
1782 -- Set true if Expr is a subscript
1784 Is_Unconstrained_Subscr_Ref : Boolean;
1785 -- Set true if Expr is a subscript of an unconstrained array. In this
1786 -- case we do not attempt to do an analysis of the value against the
1787 -- range of the subscript, since we don't know the actual subtype.
1790 -- Set to True if Expr should be regarded as a real value even though
1791 -- the type of Expr might be discrete.
1793 procedure Bad_Value;
1794 -- Procedure called if value is determined to be out of range
1800 procedure Bad_Value is
1802 Apply_Compile_Time_Constraint_Error
1803 (Expr, "value not in range of}?", CE_Range_Check_Failed,
1808 -- Start of processing for Apply_Scalar_Range_Check
1811 -- Return if check obviously not needed
1814 -- Not needed inside generic
1818 -- Not needed if previous error
1820 or else Target_Typ = Any_Type
1821 or else Nkind (Expr) = N_Error
1823 -- Not needed for non-scalar type
1825 or else not Is_Scalar_Type (Target_Typ)
1827 -- Not needed if we know node raises CE already
1829 or else Raises_Constraint_Error (Expr)
1834 -- Now, see if checks are suppressed
1837 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
1839 if Is_Subscr_Ref then
1840 Arr := Prefix (Parnt);
1841 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
1844 if not Do_Range_Check (Expr) then
1846 -- Subscript reference. Check for Index_Checks suppressed
1848 if Is_Subscr_Ref then
1850 -- Check array type and its base type
1852 if Index_Checks_Suppressed (Arr_Typ)
1853 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
1857 -- Check array itself if it is an entity name
1859 elsif Is_Entity_Name (Arr)
1860 and then Index_Checks_Suppressed (Entity (Arr))
1864 -- Check expression itself if it is an entity name
1866 elsif Is_Entity_Name (Expr)
1867 and then Index_Checks_Suppressed (Entity (Expr))
1872 -- All other cases, check for Range_Checks suppressed
1875 -- Check target type and its base type
1877 if Range_Checks_Suppressed (Target_Typ)
1878 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
1882 -- Check expression itself if it is an entity name
1884 elsif Is_Entity_Name (Expr)
1885 and then Range_Checks_Suppressed (Entity (Expr))
1889 -- If Expr is part of an assignment statement, then check left
1890 -- side of assignment if it is an entity name.
1892 elsif Nkind (Parnt) = N_Assignment_Statement
1893 and then Is_Entity_Name (Name (Parnt))
1894 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
1901 -- Do not set range checks if they are killed
1903 if Nkind (Expr) = N_Unchecked_Type_Conversion
1904 and then Kill_Range_Check (Expr)
1909 -- Do not set range checks for any values from System.Scalar_Values
1910 -- since the whole idea of such values is to avoid checking them!
1912 if Is_Entity_Name (Expr)
1913 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
1918 -- Now see if we need a check
1920 if No (Source_Typ) then
1921 S_Typ := Etype (Expr);
1923 S_Typ := Source_Typ;
1926 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
1930 Is_Unconstrained_Subscr_Ref :=
1931 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
1933 -- Always do a range check if the source type includes infinities and
1934 -- the target type does not include infinities. We do not do this if
1935 -- range checks are killed.
1937 if Is_Floating_Point_Type (S_Typ)
1938 and then Has_Infinities (S_Typ)
1939 and then not Has_Infinities (Target_Typ)
1941 Enable_Range_Check (Expr);
1944 -- Return if we know expression is definitely in the range of the target
1945 -- type as determined by Determine_Range. Right now we only do this for
1946 -- discrete types, and not fixed-point or floating-point types.
1948 -- The additional less-precise tests below catch these cases
1950 -- Note: skip this if we are given a source_typ, since the point of
1951 -- supplying a Source_Typ is to stop us looking at the expression.
1952 -- We could sharpen this test to be out parameters only ???
1954 if Is_Discrete_Type (Target_Typ)
1955 and then Is_Discrete_Type (Etype (Expr))
1956 and then not Is_Unconstrained_Subscr_Ref
1957 and then No (Source_Typ)
1960 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
1961 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
1966 if Compile_Time_Known_Value (Tlo)
1967 and then Compile_Time_Known_Value (Thi)
1970 Lov : constant Uint := Expr_Value (Tlo);
1971 Hiv : constant Uint := Expr_Value (Thi);
1974 -- If range is null, we for sure have a constraint error
1975 -- (we don't even need to look at the value involved,
1976 -- since all possible values will raise CE).
1983 -- Otherwise determine range of value
1985 Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True);
1989 -- If definitely in range, all OK
1991 if Lo >= Lov and then Hi <= Hiv then
1994 -- If definitely not in range, warn
1996 elsif Lov > Hi or else Hiv < Lo then
2000 -- Otherwise we don't know
2012 Is_Floating_Point_Type (S_Typ)
2013 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
2015 -- Check if we can determine at compile time whether Expr is in the
2016 -- range of the target type. Note that if S_Typ is within the bounds
2017 -- of Target_Typ then this must be the case. This check is meaningful
2018 -- only if this is not a conversion between integer and real types.
2020 if not Is_Unconstrained_Subscr_Ref
2022 Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
2024 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
2026 Is_In_Range (Expr, Target_Typ,
2027 Assume_Valid => True,
2028 Fixed_Int => Fixed_Int,
2029 Int_Real => Int_Real))
2033 elsif Is_Out_Of_Range (Expr, Target_Typ,
2034 Assume_Valid => True,
2035 Fixed_Int => Fixed_Int,
2036 Int_Real => Int_Real)
2041 -- In the floating-point case, we only do range checks if the type is
2042 -- constrained. We definitely do NOT want range checks for unconstrained
2043 -- types, since we want to have infinities
2045 elsif Is_Floating_Point_Type (S_Typ) then
2046 if Is_Constrained (S_Typ) then
2047 Enable_Range_Check (Expr);
2050 -- For all other cases we enable a range check unconditionally
2053 Enable_Range_Check (Expr);
2056 end Apply_Scalar_Range_Check;
2058 ----------------------------------
2059 -- Apply_Selected_Length_Checks --
2060 ----------------------------------
2062 procedure Apply_Selected_Length_Checks
2064 Target_Typ : Entity_Id;
2065 Source_Typ : Entity_Id;
2066 Do_Static : Boolean)
2069 R_Result : Check_Result;
2072 Loc : constant Source_Ptr := Sloc (Ck_Node);
2073 Checks_On : constant Boolean :=
2074 (not Index_Checks_Suppressed (Target_Typ))
2076 (not Length_Checks_Suppressed (Target_Typ));
2079 if not Expander_Active then
2084 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2086 for J in 1 .. 2 loop
2087 R_Cno := R_Result (J);
2088 exit when No (R_Cno);
2090 -- A length check may mention an Itype which is attached to a
2091 -- subsequent node. At the top level in a package this can cause
2092 -- an order-of-elaboration problem, so we make sure that the itype
2093 -- is referenced now.
2095 if Ekind (Current_Scope) = E_Package
2096 and then Is_Compilation_Unit (Current_Scope)
2098 Ensure_Defined (Target_Typ, Ck_Node);
2100 if Present (Source_Typ) then
2101 Ensure_Defined (Source_Typ, Ck_Node);
2103 elsif Is_Itype (Etype (Ck_Node)) then
2104 Ensure_Defined (Etype (Ck_Node), Ck_Node);
2108 -- If the item is a conditional raise of constraint error, then have
2109 -- a look at what check is being performed and ???
2111 if Nkind (R_Cno) = N_Raise_Constraint_Error
2112 and then Present (Condition (R_Cno))
2114 Cond := Condition (R_Cno);
2116 -- Case where node does not now have a dynamic check
2118 if not Has_Dynamic_Length_Check (Ck_Node) then
2120 -- If checks are on, just insert the check
2123 Insert_Action (Ck_Node, R_Cno);
2125 if not Do_Static then
2126 Set_Has_Dynamic_Length_Check (Ck_Node);
2129 -- If checks are off, then analyze the length check after
2130 -- temporarily attaching it to the tree in case the relevant
2131 -- condition can be evaluted at compile time. We still want a
2132 -- compile time warning in this case.
2135 Set_Parent (R_Cno, Ck_Node);
2140 -- Output a warning if the condition is known to be True
2142 if Is_Entity_Name (Cond)
2143 and then Entity (Cond) = Standard_True
2145 Apply_Compile_Time_Constraint_Error
2146 (Ck_Node, "wrong length for array of}?",
2147 CE_Length_Check_Failed,
2151 -- If we were only doing a static check, or if checks are not
2152 -- on, then we want to delete the check, since it is not needed.
2153 -- We do this by replacing the if statement by a null statement
2155 elsif Do_Static or else not Checks_On then
2156 Remove_Warning_Messages (R_Cno);
2157 Rewrite (R_Cno, Make_Null_Statement (Loc));
2161 Install_Static_Check (R_Cno, Loc);
2164 end Apply_Selected_Length_Checks;
2166 ---------------------------------
2167 -- Apply_Selected_Range_Checks --
2168 ---------------------------------
2170 procedure Apply_Selected_Range_Checks
2172 Target_Typ : Entity_Id;
2173 Source_Typ : Entity_Id;
2174 Do_Static : Boolean)
2177 R_Result : Check_Result;
2180 Loc : constant Source_Ptr := Sloc (Ck_Node);
2181 Checks_On : constant Boolean :=
2182 (not Index_Checks_Suppressed (Target_Typ))
2184 (not Range_Checks_Suppressed (Target_Typ));
2187 if not Expander_Active or else not Checks_On then
2192 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2194 for J in 1 .. 2 loop
2196 R_Cno := R_Result (J);
2197 exit when No (R_Cno);
2199 -- If the item is a conditional raise of constraint error, then have
2200 -- a look at what check is being performed and ???
2202 if Nkind (R_Cno) = N_Raise_Constraint_Error
2203 and then Present (Condition (R_Cno))
2205 Cond := Condition (R_Cno);
2207 if not Has_Dynamic_Range_Check (Ck_Node) then
2208 Insert_Action (Ck_Node, R_Cno);
2210 if not Do_Static then
2211 Set_Has_Dynamic_Range_Check (Ck_Node);
2215 -- Output a warning if the condition is known to be True
2217 if Is_Entity_Name (Cond)
2218 and then Entity (Cond) = Standard_True
2220 -- Since an N_Range is technically not an expression, we have
2221 -- to set one of the bounds to C_E and then just flag the
2222 -- N_Range. The warning message will point to the lower bound
2223 -- and complain about a range, which seems OK.
2225 if Nkind (Ck_Node) = N_Range then
2226 Apply_Compile_Time_Constraint_Error
2227 (Low_Bound (Ck_Node), "static range out of bounds of}?",
2228 CE_Range_Check_Failed,
2232 Set_Raises_Constraint_Error (Ck_Node);
2235 Apply_Compile_Time_Constraint_Error
2236 (Ck_Node, "static value out of range of}?",
2237 CE_Range_Check_Failed,
2242 -- If we were only doing a static check, or if checks are not
2243 -- on, then we want to delete the check, since it is not needed.
2244 -- We do this by replacing the if statement by a null statement
2246 elsif Do_Static or else not Checks_On then
2247 Remove_Warning_Messages (R_Cno);
2248 Rewrite (R_Cno, Make_Null_Statement (Loc));
2252 Install_Static_Check (R_Cno, Loc);
2255 end Apply_Selected_Range_Checks;
2257 -------------------------------
2258 -- Apply_Static_Length_Check --
2259 -------------------------------
2261 procedure Apply_Static_Length_Check
2263 Target_Typ : Entity_Id;
2264 Source_Typ : Entity_Id := Empty)
2267 Apply_Selected_Length_Checks
2268 (Expr, Target_Typ, Source_Typ, Do_Static => True);
2269 end Apply_Static_Length_Check;
2271 -------------------------------------
2272 -- Apply_Subscript_Validity_Checks --
2273 -------------------------------------
2275 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
2279 pragma Assert (Nkind (Expr) = N_Indexed_Component);
2281 -- Loop through subscripts
2283 Sub := First (Expressions (Expr));
2284 while Present (Sub) loop
2286 -- Check one subscript. Note that we do not worry about enumeration
2287 -- type with holes, since we will convert the value to a Pos value
2288 -- for the subscript, and that convert will do the necessary validity
2291 Ensure_Valid (Sub, Holes_OK => True);
2293 -- Move to next subscript
2297 end Apply_Subscript_Validity_Checks;
2299 ----------------------------------
2300 -- Apply_Type_Conversion_Checks --
2301 ----------------------------------
2303 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
2304 Target_Type : constant Entity_Id := Etype (N);
2305 Target_Base : constant Entity_Id := Base_Type (Target_Type);
2306 Expr : constant Node_Id := Expression (N);
2307 Expr_Type : constant Entity_Id := Etype (Expr);
2310 if Inside_A_Generic then
2313 -- Skip these checks if serious errors detected, there are some nasty
2314 -- situations of incomplete trees that blow things up.
2316 elsif Serious_Errors_Detected > 0 then
2319 -- Scalar type conversions of the form Target_Type (Expr) require a
2320 -- range check if we cannot be sure that Expr is in the base type of
2321 -- Target_Typ and also that Expr is in the range of Target_Typ. These
2322 -- are not quite the same condition from an implementation point of
2323 -- view, but clearly the second includes the first.
2325 elsif Is_Scalar_Type (Target_Type) then
2327 Conv_OK : constant Boolean := Conversion_OK (N);
2328 -- If the Conversion_OK flag on the type conversion is set and no
2329 -- floating point type is involved in the type conversion then
2330 -- fixed point values must be read as integral values.
2332 Float_To_Int : constant Boolean :=
2333 Is_Floating_Point_Type (Expr_Type)
2334 and then Is_Integer_Type (Target_Type);
2337 if not Overflow_Checks_Suppressed (Target_Base)
2339 In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK)
2340 and then not Float_To_Int
2342 Activate_Overflow_Check (N);
2345 if not Range_Checks_Suppressed (Target_Type)
2346 and then not Range_Checks_Suppressed (Expr_Type)
2348 if Float_To_Int then
2349 Apply_Float_Conversion_Check (Expr, Target_Type);
2351 Apply_Scalar_Range_Check
2352 (Expr, Target_Type, Fixed_Int => Conv_OK);
2357 elsif Comes_From_Source (N)
2358 and then not Discriminant_Checks_Suppressed (Target_Type)
2359 and then Is_Record_Type (Target_Type)
2360 and then Is_Derived_Type (Target_Type)
2361 and then not Is_Tagged_Type (Target_Type)
2362 and then not Is_Constrained (Target_Type)
2363 and then Present (Stored_Constraint (Target_Type))
2365 -- An unconstrained derived type may have inherited discriminant
2366 -- Build an actual discriminant constraint list using the stored
2367 -- constraint, to verify that the expression of the parent type
2368 -- satisfies the constraints imposed by the (unconstrained!)
2369 -- derived type. This applies to value conversions, not to view
2370 -- conversions of tagged types.
2373 Loc : constant Source_Ptr := Sloc (N);
2375 Constraint : Elmt_Id;
2376 Discr_Value : Node_Id;
2379 New_Constraints : constant Elist_Id := New_Elmt_List;
2380 Old_Constraints : constant Elist_Id :=
2381 Discriminant_Constraint (Expr_Type);
2384 Constraint := First_Elmt (Stored_Constraint (Target_Type));
2385 while Present (Constraint) loop
2386 Discr_Value := Node (Constraint);
2388 if Is_Entity_Name (Discr_Value)
2389 and then Ekind (Entity (Discr_Value)) = E_Discriminant
2391 Discr := Corresponding_Discriminant (Entity (Discr_Value));
2394 and then Scope (Discr) = Base_Type (Expr_Type)
2396 -- Parent is constrained by new discriminant. Obtain
2397 -- Value of original discriminant in expression. If the
2398 -- new discriminant has been used to constrain more than
2399 -- one of the stored discriminants, this will provide the
2400 -- required consistency check.
2403 Make_Selected_Component (Loc,
2405 Duplicate_Subexpr_No_Checks
2406 (Expr, Name_Req => True),
2408 Make_Identifier (Loc, Chars (Discr))),
2412 -- Discriminant of more remote ancestor ???
2417 -- Derived type definition has an explicit value for this
2418 -- stored discriminant.
2422 (Duplicate_Subexpr_No_Checks (Discr_Value),
2426 Next_Elmt (Constraint);
2429 -- Use the unconstrained expression type to retrieve the
2430 -- discriminants of the parent, and apply momentarily the
2431 -- discriminant constraint synthesized above.
2433 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
2434 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
2435 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
2438 Make_Raise_Constraint_Error (Loc,
2440 Reason => CE_Discriminant_Check_Failed));
2443 -- For arrays, conversions are applied during expansion, to take into
2444 -- accounts changes of representation. The checks become range checks on
2445 -- the base type or length checks on the subtype, depending on whether
2446 -- the target type is unconstrained or constrained.
2451 end Apply_Type_Conversion_Checks;
2453 ----------------------------------------------
2454 -- Apply_Universal_Integer_Attribute_Checks --
2455 ----------------------------------------------
2457 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
2458 Loc : constant Source_Ptr := Sloc (N);
2459 Typ : constant Entity_Id := Etype (N);
2462 if Inside_A_Generic then
2465 -- Nothing to do if checks are suppressed
2467 elsif Range_Checks_Suppressed (Typ)
2468 and then Overflow_Checks_Suppressed (Typ)
2472 -- Nothing to do if the attribute does not come from source. The
2473 -- internal attributes we generate of this type do not need checks,
2474 -- and furthermore the attempt to check them causes some circular
2475 -- elaboration orders when dealing with packed types.
2477 elsif not Comes_From_Source (N) then
2480 -- If the prefix is a selected component that depends on a discriminant
2481 -- the check may improperly expose a discriminant instead of using
2482 -- the bounds of the object itself. Set the type of the attribute to
2483 -- the base type of the context, so that a check will be imposed when
2484 -- needed (e.g. if the node appears as an index).
2486 elsif Nkind (Prefix (N)) = N_Selected_Component
2487 and then Ekind (Typ) = E_Signed_Integer_Subtype
2488 and then Depends_On_Discriminant (Scalar_Range (Typ))
2490 Set_Etype (N, Base_Type (Typ));
2492 -- Otherwise, replace the attribute node with a type conversion node
2493 -- whose expression is the attribute, retyped to universal integer, and
2494 -- whose subtype mark is the target type. The call to analyze this
2495 -- conversion will set range and overflow checks as required for proper
2496 -- detection of an out of range value.
2499 Set_Etype (N, Universal_Integer);
2500 Set_Analyzed (N, True);
2503 Make_Type_Conversion (Loc,
2504 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
2505 Expression => Relocate_Node (N)));
2507 Analyze_And_Resolve (N, Typ);
2510 end Apply_Universal_Integer_Attribute_Checks;
2512 -------------------------------
2513 -- Build_Discriminant_Checks --
2514 -------------------------------
2516 function Build_Discriminant_Checks
2518 T_Typ : Entity_Id) return Node_Id
2520 Loc : constant Source_Ptr := Sloc (N);
2523 Disc_Ent : Entity_Id;
2527 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
2529 ----------------------------------
2530 -- Aggregate_Discriminant_Value --
2531 ----------------------------------
2533 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
2537 -- The aggregate has been normalized with named associations. We use
2538 -- the Chars field to locate the discriminant to take into account
2539 -- discriminants in derived types, which carry the same name as those
2542 Assoc := First (Component_Associations (N));
2543 while Present (Assoc) loop
2544 if Chars (First (Choices (Assoc))) = Chars (Disc) then
2545 return Expression (Assoc);
2551 -- Discriminant must have been found in the loop above
2553 raise Program_Error;
2554 end Aggregate_Discriminant_Val;
2556 -- Start of processing for Build_Discriminant_Checks
2559 -- Loop through discriminants evolving the condition
2562 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
2564 -- For a fully private type, use the discriminants of the parent type
2566 if Is_Private_Type (T_Typ)
2567 and then No (Full_View (T_Typ))
2569 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
2571 Disc_Ent := First_Discriminant (T_Typ);
2574 while Present (Disc) loop
2575 Dval := Node (Disc);
2577 if Nkind (Dval) = N_Identifier
2578 and then Ekind (Entity (Dval)) = E_Discriminant
2580 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
2582 Dval := Duplicate_Subexpr_No_Checks (Dval);
2585 -- If we have an Unchecked_Union node, we can infer the discriminants
2588 if Is_Unchecked_Union (Base_Type (T_Typ)) then
2590 Get_Discriminant_Value (
2591 First_Discriminant (T_Typ),
2593 Stored_Constraint (T_Typ)));
2595 elsif Nkind (N) = N_Aggregate then
2597 Duplicate_Subexpr_No_Checks
2598 (Aggregate_Discriminant_Val (Disc_Ent));
2602 Make_Selected_Component (Loc,
2604 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
2606 Make_Identifier (Loc, Chars (Disc_Ent)));
2608 Set_Is_In_Discriminant_Check (Dref);
2611 Evolve_Or_Else (Cond,
2614 Right_Opnd => Dval));
2617 Next_Discriminant (Disc_Ent);
2621 end Build_Discriminant_Checks;
2627 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
2635 -- Always check if not simple entity
2637 if Nkind (Nod) not in N_Has_Entity
2638 or else not Comes_From_Source (Nod)
2643 -- Look up tree for short circuit
2650 -- Done if out of subexpression (note that we allow generated stuff
2651 -- such as itype declarations in this context, to keep the loop going
2652 -- since we may well have generated such stuff in complex situations.
2653 -- Also done if no parent (probably an error condition, but no point
2654 -- in behaving nasty if we find it!)
2657 or else (K not in N_Subexpr and then Comes_From_Source (P))
2661 -- Or/Or Else case, where test is part of the right operand, or is
2662 -- part of one of the actions associated with the right operand, and
2663 -- the left operand is an equality test.
2665 elsif K = N_Op_Or then
2666 exit when N = Right_Opnd (P)
2667 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2669 elsif K = N_Or_Else then
2670 exit when (N = Right_Opnd (P)
2673 and then List_Containing (N) = Actions (P)))
2674 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2676 -- Similar test for the And/And then case, where the left operand
2677 -- is an inequality test.
2679 elsif K = N_Op_And then
2680 exit when N = Right_Opnd (P)
2681 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2683 elsif K = N_And_Then then
2684 exit when (N = Right_Opnd (P)
2687 and then List_Containing (N) = Actions (P)))
2688 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2694 -- If we fall through the loop, then we have a conditional with an
2695 -- appropriate test as its left operand. So test further.
2698 R := Right_Opnd (L);
2701 -- Left operand of test must match original variable
2703 if Nkind (L) not in N_Has_Entity
2704 or else Entity (L) /= Entity (Nod)
2709 -- Right operand of test must be key value (zero or null)
2712 when Access_Check =>
2713 if not Known_Null (R) then
2717 when Division_Check =>
2718 if not Compile_Time_Known_Value (R)
2719 or else Expr_Value (R) /= Uint_0
2725 raise Program_Error;
2728 -- Here we have the optimizable case, warn if not short-circuited
2730 if K = N_Op_And or else K = N_Op_Or then
2732 when Access_Check =>
2734 ("Constraint_Error may be raised (access check)?",
2736 when Division_Check =>
2738 ("Constraint_Error may be raised (zero divide)?",
2742 raise Program_Error;
2745 if K = N_Op_And then
2746 Error_Msg_N ("use `AND THEN` instead of AND?", P);
2748 Error_Msg_N ("use `OR ELSE` instead of OR?", P);
2751 -- If not short-circuited, we need the ckeck
2755 -- If short-circuited, we can omit the check
2762 -----------------------------------
2763 -- Check_Valid_Lvalue_Subscripts --
2764 -----------------------------------
2766 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
2768 -- Skip this if range checks are suppressed
2770 if Range_Checks_Suppressed (Etype (Expr)) then
2773 -- Only do this check for expressions that come from source. We assume
2774 -- that expander generated assignments explicitly include any necessary
2775 -- checks. Note that this is not just an optimization, it avoids
2776 -- infinite recursions!
2778 elsif not Comes_From_Source (Expr) then
2781 -- For a selected component, check the prefix
2783 elsif Nkind (Expr) = N_Selected_Component then
2784 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2787 -- Case of indexed component
2789 elsif Nkind (Expr) = N_Indexed_Component then
2790 Apply_Subscript_Validity_Checks (Expr);
2792 -- Prefix may itself be or contain an indexed component, and these
2793 -- subscripts need checking as well.
2795 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2797 end Check_Valid_Lvalue_Subscripts;
2799 ----------------------------------
2800 -- Null_Exclusion_Static_Checks --
2801 ----------------------------------
2803 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
2804 Error_Node : Node_Id;
2806 Has_Null : constant Boolean := Has_Null_Exclusion (N);
2807 K : constant Node_Kind := Nkind (N);
2812 (K = N_Component_Declaration
2813 or else K = N_Discriminant_Specification
2814 or else K = N_Function_Specification
2815 or else K = N_Object_Declaration
2816 or else K = N_Parameter_Specification);
2818 if K = N_Function_Specification then
2819 Typ := Etype (Defining_Entity (N));
2821 Typ := Etype (Defining_Identifier (N));
2825 when N_Component_Declaration =>
2826 if Present (Access_Definition (Component_Definition (N))) then
2827 Error_Node := Component_Definition (N);
2829 Error_Node := Subtype_Indication (Component_Definition (N));
2832 when N_Discriminant_Specification =>
2833 Error_Node := Discriminant_Type (N);
2835 when N_Function_Specification =>
2836 Error_Node := Result_Definition (N);
2838 when N_Object_Declaration =>
2839 Error_Node := Object_Definition (N);
2841 when N_Parameter_Specification =>
2842 Error_Node := Parameter_Type (N);
2845 raise Program_Error;
2850 -- Enforce legality rule 3.10 (13): A null exclusion can only be
2851 -- applied to an access [sub]type.
2853 if not Is_Access_Type (Typ) then
2855 ("`NOT NULL` allowed only for an access type", Error_Node);
2857 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
2858 -- be applied to a [sub]type that does not exclude null already.
2860 elsif Can_Never_Be_Null (Typ)
2861 and then Comes_From_Source (Typ)
2864 ("`NOT NULL` not allowed (& already excludes null)",
2869 -- Check that null-excluding objects are always initialized, except for
2870 -- deferred constants, for which the expression will appear in the full
2873 if K = N_Object_Declaration
2874 and then No (Expression (N))
2875 and then not Constant_Present (N)
2876 and then not No_Initialization (N)
2878 -- Add an expression that assigns null. This node is needed by
2879 -- Apply_Compile_Time_Constraint_Error, which will replace this with
2880 -- a Constraint_Error node.
2882 Set_Expression (N, Make_Null (Sloc (N)));
2883 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
2885 Apply_Compile_Time_Constraint_Error
2886 (N => Expression (N),
2887 Msg => "(Ada 2005) null-excluding objects must be initialized?",
2888 Reason => CE_Null_Not_Allowed);
2891 -- Check that a null-excluding component, formal or object is not being
2892 -- assigned a null value. Otherwise generate a warning message and
2893 -- replace Expression (N) by an N_Constraint_Error node.
2895 if K /= N_Function_Specification then
2896 Expr := Expression (N);
2898 if Present (Expr) and then Known_Null (Expr) then
2900 when N_Component_Declaration |
2901 N_Discriminant_Specification =>
2902 Apply_Compile_Time_Constraint_Error
2904 Msg => "(Ada 2005) null not allowed " &
2905 "in null-excluding components?",
2906 Reason => CE_Null_Not_Allowed);
2908 when N_Object_Declaration =>
2909 Apply_Compile_Time_Constraint_Error
2911 Msg => "(Ada 2005) null not allowed " &
2912 "in null-excluding objects?",
2913 Reason => CE_Null_Not_Allowed);
2915 when N_Parameter_Specification =>
2916 Apply_Compile_Time_Constraint_Error
2918 Msg => "(Ada 2005) null not allowed " &
2919 "in null-excluding formals?",
2920 Reason => CE_Null_Not_Allowed);
2927 end Null_Exclusion_Static_Checks;
2929 ----------------------------------
2930 -- Conditional_Statements_Begin --
2931 ----------------------------------
2933 procedure Conditional_Statements_Begin is
2935 Saved_Checks_TOS := Saved_Checks_TOS + 1;
2937 -- If stack overflows, kill all checks, that way we know to simply reset
2938 -- the number of saved checks to zero on return. This should never occur
2941 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2944 -- In the normal case, we just make a new stack entry saving the current
2945 -- number of saved checks for a later restore.
2948 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
2950 if Debug_Flag_CC then
2951 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
2955 end Conditional_Statements_Begin;
2957 --------------------------------
2958 -- Conditional_Statements_End --
2959 --------------------------------
2961 procedure Conditional_Statements_End is
2963 pragma Assert (Saved_Checks_TOS > 0);
2965 -- If the saved checks stack overflowed, then we killed all checks, so
2966 -- setting the number of saved checks back to zero is correct. This
2967 -- should never occur in practice.
2969 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2970 Num_Saved_Checks := 0;
2972 -- In the normal case, restore the number of saved checks from the top
2976 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
2977 if Debug_Flag_CC then
2978 w ("Conditional_Statements_End: Num_Saved_Checks = ",
2983 Saved_Checks_TOS := Saved_Checks_TOS - 1;
2984 end Conditional_Statements_End;
2986 ---------------------
2987 -- Determine_Range --
2988 ---------------------
2990 Cache_Size : constant := 2 ** 10;
2991 type Cache_Index is range 0 .. Cache_Size - 1;
2992 -- Determine size of below cache (power of 2 is more efficient!)
2994 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
2995 Determine_Range_Cache_V : array (Cache_Index) of Boolean;
2996 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
2997 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
2998 -- The above arrays are used to implement a small direct cache for
2999 -- Determine_Range calls. Because of the way Determine_Range recursively
3000 -- traces subexpressions, and because overflow checking calls the routine
3001 -- on the way up the tree, a quadratic behavior can otherwise be
3002 -- encountered in large expressions. The cache entry for node N is stored
3003 -- in the (N mod Cache_Size) entry, and can be validated by checking the
3004 -- actual node value stored there. The Range_Cache_V array records the
3005 -- setting of Assume_Valid for the cache entry.
3007 procedure Determine_Range
3012 Assume_Valid : Boolean := False)
3014 Typ : Entity_Id := Etype (N);
3015 -- Type to use, may get reset to base type for possibly invalid entity
3019 -- Lo and Hi bounds of left operand
3023 -- Lo and Hi bounds of right (or only) operand
3026 -- Temp variable used to hold a bound node
3029 -- High bound of base type of expression
3033 -- Refined values for low and high bounds, after tightening
3036 -- Used in lower level calls to indicate if call succeeded
3038 Cindex : Cache_Index;
3039 -- Used to search cache
3041 function OK_Operands return Boolean;
3042 -- Used for binary operators. Determines the ranges of the left and
3043 -- right operands, and if they are both OK, returns True, and puts
3044 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
3050 function OK_Operands return Boolean is
3053 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
3060 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3064 -- Start of processing for Determine_Range
3067 -- Prevent junk warnings by initializing range variables
3074 -- If type is not defined, we can't determine its range
3078 -- We don't deal with anything except discrete types
3080 or else not Is_Discrete_Type (Typ)
3082 -- Ignore type for which an error has been posted, since range in
3083 -- this case may well be a bogosity deriving from the error. Also
3084 -- ignore if error posted on the reference node.
3086 or else Error_Posted (N) or else Error_Posted (Typ)
3092 -- For all other cases, we can determine the range
3096 -- If value is compile time known, then the possible range is the one
3097 -- value that we know this expression definitely has!
3099 if Compile_Time_Known_Value (N) then
3100 Lo := Expr_Value (N);
3105 -- Return if already in the cache
3107 Cindex := Cache_Index (N mod Cache_Size);
3109 if Determine_Range_Cache_N (Cindex) = N
3111 Determine_Range_Cache_V (Cindex) = Assume_Valid
3113 Lo := Determine_Range_Cache_Lo (Cindex);
3114 Hi := Determine_Range_Cache_Hi (Cindex);
3118 -- Otherwise, start by finding the bounds of the type of the expression,
3119 -- the value cannot be outside this range (if it is, then we have an
3120 -- overflow situation, which is a separate check, we are talking here
3121 -- only about the expression value).
3123 -- First a check, never try to find the bounds of a generic type, since
3124 -- these bounds are always junk values, and it is only valid to look at
3125 -- the bounds in an instance.
3127 if Is_Generic_Type (Typ) then
3132 -- First step, change to use base type unless we know the value is valid
3134 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
3135 or else Assume_No_Invalid_Values
3136 or else Assume_Valid
3140 Typ := Underlying_Type (Base_Type (Typ));
3143 -- We use the actual bound unless it is dynamic, in which case use the
3144 -- corresponding base type bound if possible. If we can't get a bound
3145 -- then we figure we can't determine the range (a peculiar case, that
3146 -- perhaps cannot happen, but there is no point in bombing in this
3147 -- optimization circuit.
3149 -- First the low bound
3151 Bound := Type_Low_Bound (Typ);
3153 if Compile_Time_Known_Value (Bound) then
3154 Lo := Expr_Value (Bound);
3156 elsif Compile_Time_Known_Value (Type_Low_Bound (Base_Type (Typ))) then
3157 Lo := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
3164 -- Now the high bound
3166 Bound := Type_High_Bound (Typ);
3168 -- We need the high bound of the base type later on, and this should
3169 -- always be compile time known. Again, it is not clear that this
3170 -- can ever be false, but no point in bombing.
3172 if Compile_Time_Known_Value (Type_High_Bound (Base_Type (Typ))) then
3173 Hbound := Expr_Value (Type_High_Bound (Base_Type (Typ)));
3181 -- If we have a static subtype, then that may have a tighter bound so
3182 -- use the upper bound of the subtype instead in this case.
3184 if Compile_Time_Known_Value (Bound) then
3185 Hi := Expr_Value (Bound);
3188 -- We may be able to refine this value in certain situations. If any
3189 -- refinement is possible, then Lor and Hir are set to possibly tighter
3190 -- bounds, and OK1 is set to True.
3194 -- For unary plus, result is limited by range of operand
3198 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
3200 -- For unary minus, determine range of operand, and negate it
3204 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3211 -- For binary addition, get range of each operand and do the
3212 -- addition to get the result range.
3216 Lor := Lo_Left + Lo_Right;
3217 Hir := Hi_Left + Hi_Right;
3220 -- Division is tricky. The only case we consider is where the right
3221 -- operand is a positive constant, and in this case we simply divide
3222 -- the bounds of the left operand
3226 if Lo_Right = Hi_Right
3227 and then Lo_Right > 0
3229 Lor := Lo_Left / Lo_Right;
3230 Hir := Hi_Left / Lo_Right;
3237 -- For binary subtraction, get range of each operand and do the worst
3238 -- case subtraction to get the result range.
3240 when N_Op_Subtract =>
3242 Lor := Lo_Left - Hi_Right;
3243 Hir := Hi_Left - Lo_Right;
3246 -- For MOD, if right operand is a positive constant, then result must
3247 -- be in the allowable range of mod results.
3251 if Lo_Right = Hi_Right
3252 and then Lo_Right /= 0
3254 if Lo_Right > 0 then
3256 Hir := Lo_Right - 1;
3258 else -- Lo_Right < 0
3259 Lor := Lo_Right + 1;
3268 -- For REM, if right operand is a positive constant, then result must
3269 -- be in the allowable range of mod results.
3273 if Lo_Right = Hi_Right
3274 and then Lo_Right /= 0
3277 Dval : constant Uint := (abs Lo_Right) - 1;
3280 -- The sign of the result depends on the sign of the
3281 -- dividend (but not on the sign of the divisor, hence
3282 -- the abs operation above).
3302 -- Attribute reference cases
3304 when N_Attribute_Reference =>
3305 case Attribute_Name (N) is
3307 -- For Pos/Val attributes, we can refine the range using the
3308 -- possible range of values of the attribute expression.
3310 when Name_Pos | Name_Val =>
3312 (First (Expressions (N)), OK1, Lor, Hir, Assume_Valid);
3314 -- For Length attribute, use the bounds of the corresponding
3315 -- index type to refine the range.
3319 Atyp : Entity_Id := Etype (Prefix (N));
3327 if Is_Access_Type (Atyp) then
3328 Atyp := Designated_Type (Atyp);
3331 -- For string literal, we know exact value
3333 if Ekind (Atyp) = E_String_Literal_Subtype then
3335 Lo := String_Literal_Length (Atyp);
3336 Hi := String_Literal_Length (Atyp);
3340 -- Otherwise check for expression given
3342 if No (Expressions (N)) then
3346 UI_To_Int (Expr_Value (First (Expressions (N))));
3349 Indx := First_Index (Atyp);
3350 for J in 2 .. Inum loop
3351 Indx := Next_Index (Indx);
3355 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU,
3360 (Type_High_Bound (Etype (Indx)), OK1, UL, UU,
3365 -- The maximum value for Length is the biggest
3366 -- possible gap between the values of the bounds.
3367 -- But of course, this value cannot be negative.
3369 Hir := UI_Max (Uint_0, UU - LL + 1);
3371 -- For constrained arrays, the minimum value for
3372 -- Length is taken from the actual value of the
3373 -- bounds, since the index will be exactly of
3376 if Is_Constrained (Atyp) then
3377 Lor := UI_Max (Uint_0, UL - LU + 1);
3379 -- For an unconstrained array, the minimum value
3380 -- for length is always zero.
3389 -- No special handling for other attributes
3390 -- Probably more opportunities exist here ???
3397 -- For type conversion from one discrete type to another, we can
3398 -- refine the range using the converted value.
3400 when N_Type_Conversion =>
3401 Determine_Range (Expression (N), OK1, Lor, Hir, Assume_Valid);
3403 -- Nothing special to do for all other expression kinds
3411 -- At this stage, if OK1 is true, then we know that the actual
3412 -- result of the computed expression is in the range Lor .. Hir.
3413 -- We can use this to restrict the possible range of results.
3417 -- If the refined value of the low bound is greater than the
3418 -- type high bound, then reset it to the more restrictive
3419 -- value. However, we do NOT do this for the case of a modular
3420 -- type where the possible upper bound on the value is above the
3421 -- base type high bound, because that means the result could wrap.
3424 and then not (Is_Modular_Integer_Type (Typ)
3425 and then Hir > Hbound)
3430 -- Similarly, if the refined value of the high bound is less
3431 -- than the value so far, then reset it to the more restrictive
3432 -- value. Again, we do not do this if the refined low bound is
3433 -- negative for a modular type, since this would wrap.
3436 and then not (Is_Modular_Integer_Type (Typ)
3437 and then Lor < Uint_0)
3443 -- Set cache entry for future call and we are all done
3445 Determine_Range_Cache_N (Cindex) := N;
3446 Determine_Range_Cache_V (Cindex) := Assume_Valid;
3447 Determine_Range_Cache_Lo (Cindex) := Lo;
3448 Determine_Range_Cache_Hi (Cindex) := Hi;
3451 -- If any exception occurs, it means that we have some bug in the compiler
3452 -- possibly triggered by a previous error, or by some unforseen peculiar
3453 -- occurrence. However, this is only an optimization attempt, so there is
3454 -- really no point in crashing the compiler. Instead we just decide, too
3455 -- bad, we can't figure out a range in this case after all.
3460 -- Debug flag K disables this behavior (useful for debugging)
3462 if Debug_Flag_K then
3470 end Determine_Range;
3472 ------------------------------------
3473 -- Discriminant_Checks_Suppressed --
3474 ------------------------------------
3476 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
3479 if Is_Unchecked_Union (E) then
3481 elsif Checks_May_Be_Suppressed (E) then
3482 return Is_Check_Suppressed (E, Discriminant_Check);
3486 return Scope_Suppress (Discriminant_Check);
3487 end Discriminant_Checks_Suppressed;
3489 --------------------------------
3490 -- Division_Checks_Suppressed --
3491 --------------------------------
3493 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
3495 if Present (E) and then Checks_May_Be_Suppressed (E) then
3496 return Is_Check_Suppressed (E, Division_Check);
3498 return Scope_Suppress (Division_Check);
3500 end Division_Checks_Suppressed;
3502 -----------------------------------
3503 -- Elaboration_Checks_Suppressed --
3504 -----------------------------------
3506 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
3508 -- The complication in this routine is that if we are in the dynamic
3509 -- model of elaboration, we also check All_Checks, since All_Checks
3510 -- does not set Elaboration_Check explicitly.
3513 if Kill_Elaboration_Checks (E) then
3516 elsif Checks_May_Be_Suppressed (E) then
3517 if Is_Check_Suppressed (E, Elaboration_Check) then
3519 elsif Dynamic_Elaboration_Checks then
3520 return Is_Check_Suppressed (E, All_Checks);
3527 if Scope_Suppress (Elaboration_Check) then
3529 elsif Dynamic_Elaboration_Checks then
3530 return Scope_Suppress (All_Checks);
3534 end Elaboration_Checks_Suppressed;
3536 ---------------------------
3537 -- Enable_Overflow_Check --
3538 ---------------------------
3540 procedure Enable_Overflow_Check (N : Node_Id) is
3541 Typ : constant Entity_Id := Base_Type (Etype (N));
3550 if Debug_Flag_CC then
3551 w ("Enable_Overflow_Check for node ", Int (N));
3552 Write_Str (" Source location = ");
3557 -- No check if overflow checks suppressed for type of node
3559 if Present (Etype (N))
3560 and then Overflow_Checks_Suppressed (Etype (N))
3564 -- Nothing to do for unsigned integer types, which do not overflow
3566 elsif Is_Modular_Integer_Type (Typ) then
3569 -- Nothing to do if the range of the result is known OK. We skip this
3570 -- for conversions, since the caller already did the check, and in any
3571 -- case the condition for deleting the check for a type conversion is
3574 elsif Nkind (N) /= N_Type_Conversion then
3575 Determine_Range (N, OK, Lo, Hi, Assume_Valid => True);
3577 -- Note in the test below that we assume that the range is not OK
3578 -- if a bound of the range is equal to that of the type. That's not
3579 -- quite accurate but we do this for the following reasons:
3581 -- a) The way that Determine_Range works, it will typically report
3582 -- the bounds of the value as being equal to the bounds of the
3583 -- type, because it either can't tell anything more precise, or
3584 -- does not think it is worth the effort to be more precise.
3586 -- b) It is very unusual to have a situation in which this would
3587 -- generate an unnecessary overflow check (an example would be
3588 -- a subtype with a range 0 .. Integer'Last - 1 to which the
3589 -- literal value one is added).
3591 -- c) The alternative is a lot of special casing in this routine
3592 -- which would partially duplicate Determine_Range processing.
3595 and then Lo > Expr_Value (Type_Low_Bound (Typ))
3596 and then Hi < Expr_Value (Type_High_Bound (Typ))
3598 if Debug_Flag_CC then
3599 w ("No overflow check required");
3606 -- If not in optimizing mode, set flag and we are done. We are also done
3607 -- (and just set the flag) if the type is not a discrete type, since it
3608 -- is not worth the effort to eliminate checks for other than discrete
3609 -- types. In addition, we take this same path if we have stored the
3610 -- maximum number of checks possible already (a very unlikely situation,
3611 -- but we do not want to blow up!)
3613 if Optimization_Level = 0
3614 or else not Is_Discrete_Type (Etype (N))
3615 or else Num_Saved_Checks = Saved_Checks'Last
3617 Activate_Overflow_Check (N);
3619 if Debug_Flag_CC then
3620 w ("Optimization off");
3626 -- Otherwise evaluate and check the expression
3631 Target_Type => Empty,
3637 if Debug_Flag_CC then
3638 w ("Called Find_Check");
3642 w (" Check_Num = ", Chk);
3643 w (" Ent = ", Int (Ent));
3644 Write_Str (" Ofs = ");
3649 -- If check is not of form to optimize, then set flag and we are done
3652 Activate_Overflow_Check (N);
3656 -- If check is already performed, then return without setting flag
3659 if Debug_Flag_CC then
3660 w ("Check suppressed!");
3666 -- Here we will make a new entry for the new check
3668 Activate_Overflow_Check (N);
3669 Num_Saved_Checks := Num_Saved_Checks + 1;
3670 Saved_Checks (Num_Saved_Checks) :=
3675 Target_Type => Empty);
3677 if Debug_Flag_CC then
3678 w ("Make new entry, check number = ", Num_Saved_Checks);
3679 w (" Entity = ", Int (Ent));
3680 Write_Str (" Offset = ");
3682 w (" Check_Type = O");
3683 w (" Target_Type = Empty");
3686 -- If we get an exception, then something went wrong, probably because of
3687 -- an error in the structure of the tree due to an incorrect program. Or it
3688 -- may be a bug in the optimization circuit. In either case the safest
3689 -- thing is simply to set the check flag unconditionally.
3693 Activate_Overflow_Check (N);
3695 if Debug_Flag_CC then
3696 w (" exception occurred, overflow flag set");
3700 end Enable_Overflow_Check;
3702 ------------------------
3703 -- Enable_Range_Check --
3704 ------------------------
3706 procedure Enable_Range_Check (N : Node_Id) is
3715 -- Return if unchecked type conversion with range check killed. In this
3716 -- case we never set the flag (that's what Kill_Range_Check is about!)
3718 if Nkind (N) = N_Unchecked_Type_Conversion
3719 and then Kill_Range_Check (N)
3724 -- Check for various cases where we should suppress the range check
3726 -- No check if range checks suppressed for type of node
3728 if Present (Etype (N))
3729 and then Range_Checks_Suppressed (Etype (N))
3733 -- No check if node is an entity name, and range checks are suppressed
3734 -- for this entity, or for the type of this entity.
3736 elsif Is_Entity_Name (N)
3737 and then (Range_Checks_Suppressed (Entity (N))
3738 or else Range_Checks_Suppressed (Etype (Entity (N))))
3742 -- No checks if index of array, and index checks are suppressed for
3743 -- the array object or the type of the array.
3745 elsif Nkind (Parent (N)) = N_Indexed_Component then
3747 Pref : constant Node_Id := Prefix (Parent (N));
3749 if Is_Entity_Name (Pref)
3750 and then Index_Checks_Suppressed (Entity (Pref))
3753 elsif Index_Checks_Suppressed (Etype (Pref)) then
3759 -- Debug trace output
3761 if Debug_Flag_CC then
3762 w ("Enable_Range_Check for node ", Int (N));
3763 Write_Str (" Source location = ");
3768 -- If not in optimizing mode, set flag and we are done. We are also done
3769 -- (and just set the flag) if the type is not a discrete type, since it
3770 -- is not worth the effort to eliminate checks for other than discrete
3771 -- types. In addition, we take this same path if we have stored the
3772 -- maximum number of checks possible already (a very unlikely situation,
3773 -- but we do not want to blow up!)
3775 if Optimization_Level = 0
3776 or else No (Etype (N))
3777 or else not Is_Discrete_Type (Etype (N))
3778 or else Num_Saved_Checks = Saved_Checks'Last
3780 Activate_Range_Check (N);
3782 if Debug_Flag_CC then
3783 w ("Optimization off");
3789 -- Otherwise find out the target type
3793 -- For assignment, use left side subtype
3795 if Nkind (P) = N_Assignment_Statement
3796 and then Expression (P) = N
3798 Ttyp := Etype (Name (P));
3800 -- For indexed component, use subscript subtype
3802 elsif Nkind (P) = N_Indexed_Component then
3809 Atyp := Etype (Prefix (P));
3811 if Is_Access_Type (Atyp) then
3812 Atyp := Designated_Type (Atyp);
3814 -- If the prefix is an access to an unconstrained array,
3815 -- perform check unconditionally: it depends on the bounds of
3816 -- an object and we cannot currently recognize whether the test
3817 -- may be redundant.
3819 if not Is_Constrained (Atyp) then
3820 Activate_Range_Check (N);
3824 -- Ditto if the prefix is an explicit dereference whose designated
3825 -- type is unconstrained.
3827 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
3828 and then not Is_Constrained (Atyp)
3830 Activate_Range_Check (N);
3834 Indx := First_Index (Atyp);
3835 Subs := First (Expressions (P));
3838 Ttyp := Etype (Indx);
3847 -- For now, ignore all other cases, they are not so interesting
3850 if Debug_Flag_CC then
3851 w (" target type not found, flag set");
3854 Activate_Range_Check (N);
3858 -- Evaluate and check the expression
3863 Target_Type => Ttyp,
3869 if Debug_Flag_CC then
3870 w ("Called Find_Check");
3871 w ("Target_Typ = ", Int (Ttyp));
3875 w (" Check_Num = ", Chk);
3876 w (" Ent = ", Int (Ent));
3877 Write_Str (" Ofs = ");
3882 -- If check is not of form to optimize, then set flag and we are done
3885 if Debug_Flag_CC then
3886 w (" expression not of optimizable type, flag set");
3889 Activate_Range_Check (N);
3893 -- If check is already performed, then return without setting flag
3896 if Debug_Flag_CC then
3897 w ("Check suppressed!");
3903 -- Here we will make a new entry for the new check
3905 Activate_Range_Check (N);
3906 Num_Saved_Checks := Num_Saved_Checks + 1;
3907 Saved_Checks (Num_Saved_Checks) :=
3912 Target_Type => Ttyp);
3914 if Debug_Flag_CC then
3915 w ("Make new entry, check number = ", Num_Saved_Checks);
3916 w (" Entity = ", Int (Ent));
3917 Write_Str (" Offset = ");
3919 w (" Check_Type = R");
3920 w (" Target_Type = ", Int (Ttyp));
3921 pg (Union_Id (Ttyp));
3924 -- If we get an exception, then something went wrong, probably because of
3925 -- an error in the structure of the tree due to an incorrect program. Or
3926 -- it may be a bug in the optimization circuit. In either case the safest
3927 -- thing is simply to set the check flag unconditionally.
3931 Activate_Range_Check (N);
3933 if Debug_Flag_CC then
3934 w (" exception occurred, range flag set");
3938 end Enable_Range_Check;
3944 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
3945 Typ : constant Entity_Id := Etype (Expr);
3948 -- Ignore call if we are not doing any validity checking
3950 if not Validity_Checks_On then
3953 -- Ignore call if range or validity checks suppressed on entity or type
3955 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
3958 -- No check required if expression is from the expander, we assume the
3959 -- expander will generate whatever checks are needed. Note that this is
3960 -- not just an optimization, it avoids infinite recursions!
3962 -- Unchecked conversions must be checked, unless they are initialized
3963 -- scalar values, as in a component assignment in an init proc.
3965 -- In addition, we force a check if Force_Validity_Checks is set
3967 elsif not Comes_From_Source (Expr)
3968 and then not Force_Validity_Checks
3969 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
3970 or else Kill_Range_Check (Expr))
3974 -- No check required if expression is known to have valid value
3976 elsif Expr_Known_Valid (Expr) then
3979 -- Ignore case of enumeration with holes where the flag is set not to
3980 -- worry about holes, since no special validity check is needed
3982 elsif Is_Enumeration_Type (Typ)
3983 and then Has_Non_Standard_Rep (Typ)
3988 -- No check required on the left-hand side of an assignment
3990 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
3991 and then Expr = Name (Parent (Expr))
3995 -- No check on a univeral real constant. The context will eventually
3996 -- convert it to a machine number for some target type, or report an
3999 elsif Nkind (Expr) = N_Real_Literal
4000 and then Etype (Expr) = Universal_Real
4004 -- If the expression denotes a component of a packed boolean arrray,
4005 -- no possible check applies. We ignore the old ACATS chestnuts that
4006 -- involve Boolean range True..True.
4008 -- Note: validity checks are generated for expressions that yield a
4009 -- scalar type, when it is possible to create a value that is outside of
4010 -- the type. If this is a one-bit boolean no such value exists. This is
4011 -- an optimization, and it also prevents compiler blowing up during the
4012 -- elaboration of improperly expanded packed array references.
4014 elsif Nkind (Expr) = N_Indexed_Component
4015 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
4016 and then Root_Type (Etype (Expr)) = Standard_Boolean
4020 -- An annoying special case. If this is an out parameter of a scalar
4021 -- type, then the value is not going to be accessed, therefore it is
4022 -- inappropriate to do any validity check at the call site.
4025 -- Only need to worry about scalar types
4027 if Is_Scalar_Type (Typ) then
4037 -- Find actual argument (which may be a parameter association)
4038 -- and the parent of the actual argument (the call statement)
4043 if Nkind (P) = N_Parameter_Association then
4048 -- Only need to worry if we are argument of a procedure call
4049 -- since functions don't have out parameters. If this is an
4050 -- indirect or dispatching call, get signature from the
4053 if Nkind (P) = N_Procedure_Call_Statement then
4054 L := Parameter_Associations (P);
4056 if Is_Entity_Name (Name (P)) then
4057 E := Entity (Name (P));
4059 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
4060 E := Etype (Name (P));
4063 -- Only need to worry if there are indeed actuals, and if
4064 -- this could be a procedure call, otherwise we cannot get a
4065 -- match (either we are not an argument, or the mode of the
4066 -- formal is not OUT). This test also filters out the
4069 if Is_Non_Empty_List (L)
4070 and then Is_Subprogram (E)
4072 -- This is the loop through parameters, looking for an
4073 -- OUT parameter for which we are the argument.
4075 F := First_Formal (E);
4077 while Present (F) loop
4078 if Ekind (F) = E_Out_Parameter and then A = N then
4091 -- If we fall through, a validity check is required
4093 Insert_Valid_Check (Expr);
4095 if Is_Entity_Name (Expr)
4096 and then Safe_To_Capture_Value (Expr, Entity (Expr))
4098 Set_Is_Known_Valid (Entity (Expr));
4102 ----------------------
4103 -- Expr_Known_Valid --
4104 ----------------------
4106 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
4107 Typ : constant Entity_Id := Etype (Expr);
4110 -- Non-scalar types are always considered valid, since they never give
4111 -- rise to the issues of erroneous or bounded error behavior that are
4112 -- the concern. In formal reference manual terms the notion of validity
4113 -- only applies to scalar types. Note that even when packed arrays are
4114 -- represented using modular types, they are still arrays semantically,
4115 -- so they are also always valid (in particular, the unused bits can be
4116 -- random rubbish without affecting the validity of the array value).
4118 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
4121 -- If no validity checking, then everything is considered valid
4123 elsif not Validity_Checks_On then
4126 -- Floating-point types are considered valid unless floating-point
4127 -- validity checks have been specifically turned on.
4129 elsif Is_Floating_Point_Type (Typ)
4130 and then not Validity_Check_Floating_Point
4134 -- If the expression is the value of an object that is known to be
4135 -- valid, then clearly the expression value itself is valid.
4137 elsif Is_Entity_Name (Expr)
4138 and then Is_Known_Valid (Entity (Expr))
4142 -- References to discriminants are always considered valid. The value
4143 -- of a discriminant gets checked when the object is built. Within the
4144 -- record, we consider it valid, and it is important to do so, since
4145 -- otherwise we can try to generate bogus validity checks which
4146 -- reference discriminants out of scope. Discriminants of concurrent
4147 -- types are excluded for the same reason.
4149 elsif Is_Entity_Name (Expr)
4150 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
4154 -- If the type is one for which all values are known valid, then we are
4155 -- sure that the value is valid except in the slightly odd case where
4156 -- the expression is a reference to a variable whose size has been
4157 -- explicitly set to a value greater than the object size.
4159 elsif Is_Known_Valid (Typ) then
4160 if Is_Entity_Name (Expr)
4161 and then Ekind (Entity (Expr)) = E_Variable
4162 and then Esize (Entity (Expr)) > Esize (Typ)
4169 -- Integer and character literals always have valid values, where
4170 -- appropriate these will be range checked in any case.
4172 elsif Nkind (Expr) = N_Integer_Literal
4174 Nkind (Expr) = N_Character_Literal
4178 -- If we have a type conversion or a qualification of a known valid
4179 -- value, then the result will always be valid.
4181 elsif Nkind (Expr) = N_Type_Conversion
4183 Nkind (Expr) = N_Qualified_Expression
4185 return Expr_Known_Valid (Expression (Expr));
4187 -- The result of any operator is always considered valid, since we
4188 -- assume the necessary checks are done by the operator. For operators
4189 -- on floating-point operations, we must also check when the operation
4190 -- is the right-hand side of an assignment, or is an actual in a call.
4192 elsif Nkind (Expr) in N_Op then
4193 if Is_Floating_Point_Type (Typ)
4194 and then Validity_Check_Floating_Point
4196 (Nkind (Parent (Expr)) = N_Assignment_Statement
4197 or else Nkind (Parent (Expr)) = N_Function_Call
4198 or else Nkind (Parent (Expr)) = N_Parameter_Association)
4205 -- The result of a membership test is always valid, since it is true or
4206 -- false, there are no other possibilities.
4208 elsif Nkind (Expr) in N_Membership_Test then
4211 -- For all other cases, we do not know the expression is valid
4216 end Expr_Known_Valid;
4222 procedure Find_Check
4224 Check_Type : Character;
4225 Target_Type : Entity_Id;
4226 Entry_OK : out Boolean;
4227 Check_Num : out Nat;
4228 Ent : out Entity_Id;
4231 function Within_Range_Of
4232 (Target_Type : Entity_Id;
4233 Check_Type : Entity_Id) return Boolean;
4234 -- Given a requirement for checking a range against Target_Type, and
4235 -- and a range Check_Type against which a check has already been made,
4236 -- determines if the check against check type is sufficient to ensure
4237 -- that no check against Target_Type is required.
4239 ---------------------
4240 -- Within_Range_Of --
4241 ---------------------
4243 function Within_Range_Of
4244 (Target_Type : Entity_Id;
4245 Check_Type : Entity_Id) return Boolean
4248 if Target_Type = Check_Type then
4253 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
4254 Thi : constant Node_Id := Type_High_Bound (Target_Type);
4255 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
4256 Chi : constant Node_Id := Type_High_Bound (Check_Type);
4260 or else (Compile_Time_Known_Value (Tlo)
4262 Compile_Time_Known_Value (Clo)
4264 Expr_Value (Clo) >= Expr_Value (Tlo)))
4267 or else (Compile_Time_Known_Value (Thi)
4269 Compile_Time_Known_Value (Chi)
4271 Expr_Value (Chi) <= Expr_Value (Clo)))
4279 end Within_Range_Of;
4281 -- Start of processing for Find_Check
4284 -- Establish default, in case no entry is found
4288 -- Case of expression is simple entity reference
4290 if Is_Entity_Name (Expr) then
4291 Ent := Entity (Expr);
4294 -- Case of expression is entity + known constant
4296 elsif Nkind (Expr) = N_Op_Add
4297 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4298 and then Is_Entity_Name (Left_Opnd (Expr))
4300 Ent := Entity (Left_Opnd (Expr));
4301 Ofs := Expr_Value (Right_Opnd (Expr));
4303 -- Case of expression is entity - known constant
4305 elsif Nkind (Expr) = N_Op_Subtract
4306 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4307 and then Is_Entity_Name (Left_Opnd (Expr))
4309 Ent := Entity (Left_Opnd (Expr));
4310 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
4312 -- Any other expression is not of the right form
4321 -- Come here with expression of appropriate form, check if entity is an
4322 -- appropriate one for our purposes.
4324 if (Ekind (Ent) = E_Variable
4325 or else Is_Constant_Object (Ent))
4326 and then not Is_Library_Level_Entity (Ent)
4334 -- See if there is matching check already
4336 for J in reverse 1 .. Num_Saved_Checks loop
4338 SC : Saved_Check renames Saved_Checks (J);
4341 if SC.Killed = False
4342 and then SC.Entity = Ent
4343 and then SC.Offset = Ofs
4344 and then SC.Check_Type = Check_Type
4345 and then Within_Range_Of (Target_Type, SC.Target_Type)
4353 -- If we fall through entry was not found
4358 ---------------------------------
4359 -- Generate_Discriminant_Check --
4360 ---------------------------------
4362 -- Note: the code for this procedure is derived from the
4363 -- Emit_Discriminant_Check Routine in trans.c.
4365 procedure Generate_Discriminant_Check (N : Node_Id) is
4366 Loc : constant Source_Ptr := Sloc (N);
4367 Pref : constant Node_Id := Prefix (N);
4368 Sel : constant Node_Id := Selector_Name (N);
4370 Orig_Comp : constant Entity_Id :=
4371 Original_Record_Component (Entity (Sel));
4372 -- The original component to be checked
4374 Discr_Fct : constant Entity_Id :=
4375 Discriminant_Checking_Func (Orig_Comp);
4376 -- The discriminant checking function
4379 -- One discriminant to be checked in the type
4381 Real_Discr : Entity_Id;
4382 -- Actual discriminant in the call
4384 Pref_Type : Entity_Id;
4385 -- Type of relevant prefix (ignoring private/access stuff)
4388 -- List of arguments for function call
4391 -- Keep track of the formal corresponding to the actual we build for
4392 -- each discriminant, in order to be able to perform the necessary type
4396 -- Selected component reference for checking function argument
4399 Pref_Type := Etype (Pref);
4401 -- Force evaluation of the prefix, so that it does not get evaluated
4402 -- twice (once for the check, once for the actual reference). Such a
4403 -- double evaluation is always a potential source of inefficiency,
4404 -- and is functionally incorrect in the volatile case, or when the
4405 -- prefix may have side-effects. An entity or a component of an
4406 -- entity requires no evaluation.
4408 if Is_Entity_Name (Pref) then
4409 if Treat_As_Volatile (Entity (Pref)) then
4410 Force_Evaluation (Pref, Name_Req => True);
4413 elsif Treat_As_Volatile (Etype (Pref)) then
4414 Force_Evaluation (Pref, Name_Req => True);
4416 elsif Nkind (Pref) = N_Selected_Component
4417 and then Is_Entity_Name (Prefix (Pref))
4422 Force_Evaluation (Pref, Name_Req => True);
4425 -- For a tagged type, use the scope of the original component to
4426 -- obtain the type, because ???
4428 if Is_Tagged_Type (Scope (Orig_Comp)) then
4429 Pref_Type := Scope (Orig_Comp);
4431 -- For an untagged derived type, use the discriminants of the parent
4432 -- which have been renamed in the derivation, possibly by a one-to-many
4433 -- discriminant constraint. For non-tagged type, initially get the Etype
4437 if Is_Derived_Type (Pref_Type)
4438 and then Number_Discriminants (Pref_Type) /=
4439 Number_Discriminants (Etype (Base_Type (Pref_Type)))
4441 Pref_Type := Etype (Base_Type (Pref_Type));
4445 -- We definitely should have a checking function, This routine should
4446 -- not be called if no discriminant checking function is present.
4448 pragma Assert (Present (Discr_Fct));
4450 -- Create the list of the actual parameters for the call. This list
4451 -- is the list of the discriminant fields of the record expression to
4452 -- be discriminant checked.
4455 Formal := First_Formal (Discr_Fct);
4456 Discr := First_Discriminant (Pref_Type);
4457 while Present (Discr) loop
4459 -- If we have a corresponding discriminant field, and a parent
4460 -- subtype is present, then we want to use the corresponding
4461 -- discriminant since this is the one with the useful value.
4463 if Present (Corresponding_Discriminant (Discr))
4464 and then Ekind (Pref_Type) = E_Record_Type
4465 and then Present (Parent_Subtype (Pref_Type))
4467 Real_Discr := Corresponding_Discriminant (Discr);
4469 Real_Discr := Discr;
4472 -- Construct the reference to the discriminant
4475 Make_Selected_Component (Loc,
4477 Unchecked_Convert_To (Pref_Type,
4478 Duplicate_Subexpr (Pref)),
4479 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
4481 -- Manually analyze and resolve this selected component. We really
4482 -- want it just as it appears above, and do not want the expander
4483 -- playing discriminal games etc with this reference. Then we append
4484 -- the argument to the list we are gathering.
4486 Set_Etype (Scomp, Etype (Real_Discr));
4487 Set_Analyzed (Scomp, True);
4488 Append_To (Args, Convert_To (Etype (Formal), Scomp));
4490 Next_Formal_With_Extras (Formal);
4491 Next_Discriminant (Discr);
4494 -- Now build and insert the call
4497 Make_Raise_Constraint_Error (Loc,
4499 Make_Function_Call (Loc,
4500 Name => New_Occurrence_Of (Discr_Fct, Loc),
4501 Parameter_Associations => Args),
4502 Reason => CE_Discriminant_Check_Failed));
4503 end Generate_Discriminant_Check;
4505 ---------------------------
4506 -- Generate_Index_Checks --
4507 ---------------------------
4509 procedure Generate_Index_Checks (N : Node_Id) is
4510 Loc : constant Source_Ptr := Sloc (N);
4511 A : constant Node_Id := Prefix (N);
4517 -- Ignore call if index checks suppressed for array object or type
4519 if (Is_Entity_Name (A) and then Index_Checks_Suppressed (Entity (A)))
4520 or else Index_Checks_Suppressed (Etype (A))
4525 -- Generate the checks
4527 Sub := First (Expressions (N));
4529 while Present (Sub) loop
4530 if Do_Range_Check (Sub) then
4531 Set_Do_Range_Check (Sub, False);
4533 -- Force evaluation except for the case of a simple name of a
4534 -- non-volatile entity.
4536 if not Is_Entity_Name (Sub)
4537 or else Treat_As_Volatile (Entity (Sub))
4539 Force_Evaluation (Sub);
4542 -- Generate a raise of constraint error with the appropriate
4543 -- reason and a condition of the form:
4545 -- Base_Type(Sub) not in array'range (subscript)
4547 -- Note that the reason we generate the conversion to the base
4548 -- type here is that we definitely want the range check to take
4549 -- place, even if it looks like the subtype is OK. Optimization
4550 -- considerations that allow us to omit the check have already
4551 -- been taken into account in the setting of the Do_Range_Check
4557 Num := New_List (Make_Integer_Literal (Loc, Ind));
4561 Make_Raise_Constraint_Error (Loc,
4565 Convert_To (Base_Type (Etype (Sub)),
4566 Duplicate_Subexpr_Move_Checks (Sub)),
4568 Make_Attribute_Reference (Loc,
4570 Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
4571 Attribute_Name => Name_Range,
4572 Expressions => Num)),
4573 Reason => CE_Index_Check_Failed));
4579 end Generate_Index_Checks;
4581 --------------------------
4582 -- Generate_Range_Check --
4583 --------------------------
4585 procedure Generate_Range_Check
4587 Target_Type : Entity_Id;
4588 Reason : RT_Exception_Code)
4590 Loc : constant Source_Ptr := Sloc (N);
4591 Source_Type : constant Entity_Id := Etype (N);
4592 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
4593 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
4596 -- First special case, if the source type is already within the range
4597 -- of the target type, then no check is needed (probably we should have
4598 -- stopped Do_Range_Check from being set in the first place, but better
4599 -- late than later in preventing junk code!
4601 -- We do NOT apply this if the source node is a literal, since in this
4602 -- case the literal has already been labeled as having the subtype of
4605 if In_Subrange_Of (Source_Type, Target_Type)
4607 (Nkind (N) = N_Integer_Literal
4609 Nkind (N) = N_Real_Literal
4611 Nkind (N) = N_Character_Literal
4614 and then Ekind (Entity (N)) = E_Enumeration_Literal))
4619 -- We need a check, so force evaluation of the node, so that it does
4620 -- not get evaluated twice (once for the check, once for the actual
4621 -- reference). Such a double evaluation is always a potential source
4622 -- of inefficiency, and is functionally incorrect in the volatile case.
4624 if not Is_Entity_Name (N)
4625 or else Treat_As_Volatile (Entity (N))
4627 Force_Evaluation (N);
4630 -- The easiest case is when Source_Base_Type and Target_Base_Type are
4631 -- the same since in this case we can simply do a direct check of the
4632 -- value of N against the bounds of Target_Type.
4634 -- [constraint_error when N not in Target_Type]
4636 -- Note: this is by far the most common case, for example all cases of
4637 -- checks on the RHS of assignments are in this category, but not all
4638 -- cases are like this. Notably conversions can involve two types.
4640 if Source_Base_Type = Target_Base_Type then
4642 Make_Raise_Constraint_Error (Loc,
4645 Left_Opnd => Duplicate_Subexpr (N),
4646 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4649 -- Next test for the case where the target type is within the bounds
4650 -- of the base type of the source type, since in this case we can
4651 -- simply convert these bounds to the base type of T to do the test.
4653 -- [constraint_error when N not in
4654 -- Source_Base_Type (Target_Type'First)
4656 -- Source_Base_Type(Target_Type'Last))]
4658 -- The conversions will always work and need no check
4660 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
4661 -- of converting from an enumeration value to an integer type, such as
4662 -- occurs for the case of generating a range check on Enum'Val(Exp)
4663 -- (which used to be handled by gigi). This is OK, since the conversion
4664 -- itself does not require a check.
4666 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
4668 Make_Raise_Constraint_Error (Loc,
4671 Left_Opnd => Duplicate_Subexpr (N),
4676 Unchecked_Convert_To (Source_Base_Type,
4677 Make_Attribute_Reference (Loc,
4679 New_Occurrence_Of (Target_Type, Loc),
4680 Attribute_Name => Name_First)),
4683 Unchecked_Convert_To (Source_Base_Type,
4684 Make_Attribute_Reference (Loc,
4686 New_Occurrence_Of (Target_Type, Loc),
4687 Attribute_Name => Name_Last)))),
4690 -- Note that at this stage we now that the Target_Base_Type is not in
4691 -- the range of the Source_Base_Type (since even the Target_Type itself
4692 -- is not in this range). It could still be the case that Source_Type is
4693 -- in range of the target base type since we have not checked that case.
4695 -- If that is the case, we can freely convert the source to the target,
4696 -- and then test the target result against the bounds.
4698 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
4700 -- We make a temporary to hold the value of the converted value
4701 -- (converted to the base type), and then we will do the test against
4704 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
4705 -- [constraint_error when Tnn not in Target_Type]
4707 -- Then the conversion itself is replaced by an occurrence of Tnn
4710 Tnn : constant Entity_Id :=
4711 Make_Defining_Identifier (Loc,
4712 Chars => New_Internal_Name ('T'));
4715 Insert_Actions (N, New_List (
4716 Make_Object_Declaration (Loc,
4717 Defining_Identifier => Tnn,
4718 Object_Definition =>
4719 New_Occurrence_Of (Target_Base_Type, Loc),
4720 Constant_Present => True,
4722 Make_Type_Conversion (Loc,
4723 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
4724 Expression => Duplicate_Subexpr (N))),
4726 Make_Raise_Constraint_Error (Loc,
4729 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4730 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4732 Reason => Reason)));
4734 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4736 -- Set the type of N, because the declaration for Tnn might not
4737 -- be analyzed yet, as is the case if N appears within a record
4738 -- declaration, as a discriminant constraint or expression.
4740 Set_Etype (N, Target_Base_Type);
4743 -- At this stage, we know that we have two scalar types, which are
4744 -- directly convertible, and where neither scalar type has a base
4745 -- range that is in the range of the other scalar type.
4747 -- The only way this can happen is with a signed and unsigned type.
4748 -- So test for these two cases:
4751 -- Case of the source is unsigned and the target is signed
4753 if Is_Unsigned_Type (Source_Base_Type)
4754 and then not Is_Unsigned_Type (Target_Base_Type)
4756 -- If the source is unsigned and the target is signed, then we
4757 -- know that the source is not shorter than the target (otherwise
4758 -- the source base type would be in the target base type range).
4760 -- In other words, the unsigned type is either the same size as
4761 -- the target, or it is larger. It cannot be smaller.
4764 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
4766 -- We only need to check the low bound if the low bound of the
4767 -- target type is non-negative. If the low bound of the target
4768 -- type is negative, then we know that we will fit fine.
4770 -- If the high bound of the target type is negative, then we
4771 -- know we have a constraint error, since we can't possibly
4772 -- have a negative source.
4774 -- With these two checks out of the way, we can do the check
4775 -- using the source type safely
4777 -- This is definitely the most annoying case!
4779 -- [constraint_error
4780 -- when (Target_Type'First >= 0
4782 -- N < Source_Base_Type (Target_Type'First))
4783 -- or else Target_Type'Last < 0
4784 -- or else N > Source_Base_Type (Target_Type'Last)];
4786 -- We turn off all checks since we know that the conversions
4787 -- will work fine, given the guards for negative values.
4790 Make_Raise_Constraint_Error (Loc,
4796 Left_Opnd => Make_Op_Ge (Loc,
4798 Make_Attribute_Reference (Loc,
4800 New_Occurrence_Of (Target_Type, Loc),
4801 Attribute_Name => Name_First),
4802 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4806 Left_Opnd => Duplicate_Subexpr (N),
4808 Convert_To (Source_Base_Type,
4809 Make_Attribute_Reference (Loc,
4811 New_Occurrence_Of (Target_Type, Loc),
4812 Attribute_Name => Name_First)))),
4817 Make_Attribute_Reference (Loc,
4818 Prefix => New_Occurrence_Of (Target_Type, Loc),
4819 Attribute_Name => Name_Last),
4820 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
4824 Left_Opnd => Duplicate_Subexpr (N),
4826 Convert_To (Source_Base_Type,
4827 Make_Attribute_Reference (Loc,
4828 Prefix => New_Occurrence_Of (Target_Type, Loc),
4829 Attribute_Name => Name_Last)))),
4832 Suppress => All_Checks);
4834 -- Only remaining possibility is that the source is signed and
4835 -- the target is unsigned.
4838 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
4839 and then Is_Unsigned_Type (Target_Base_Type));
4841 -- If the source is signed and the target is unsigned, then we
4842 -- know that the target is not shorter than the source (otherwise
4843 -- the target base type would be in the source base type range).
4845 -- In other words, the unsigned type is either the same size as
4846 -- the target, or it is larger. It cannot be smaller.
4848 -- Clearly we have an error if the source value is negative since
4849 -- no unsigned type can have negative values. If the source type
4850 -- is non-negative, then the check can be done using the target
4853 -- Tnn : constant Target_Base_Type (N) := Target_Type;
4855 -- [constraint_error
4856 -- when N < 0 or else Tnn not in Target_Type];
4858 -- We turn off all checks for the conversion of N to the target
4859 -- base type, since we generate the explicit check to ensure that
4860 -- the value is non-negative
4863 Tnn : constant Entity_Id :=
4864 Make_Defining_Identifier (Loc,
4865 Chars => New_Internal_Name ('T'));
4868 Insert_Actions (N, New_List (
4869 Make_Object_Declaration (Loc,
4870 Defining_Identifier => Tnn,
4871 Object_Definition =>
4872 New_Occurrence_Of (Target_Base_Type, Loc),
4873 Constant_Present => True,
4875 Make_Unchecked_Type_Conversion (Loc,
4877 New_Occurrence_Of (Target_Base_Type, Loc),
4878 Expression => Duplicate_Subexpr (N))),
4880 Make_Raise_Constraint_Error (Loc,
4885 Left_Opnd => Duplicate_Subexpr (N),
4886 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4890 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4892 New_Occurrence_Of (Target_Type, Loc))),
4895 Suppress => All_Checks);
4897 -- Set the Etype explicitly, because Insert_Actions may have
4898 -- placed the declaration in the freeze list for an enclosing
4899 -- construct, and thus it is not analyzed yet.
4901 Set_Etype (Tnn, Target_Base_Type);
4902 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4906 end Generate_Range_Check;
4912 function Get_Check_Id (N : Name_Id) return Check_Id is
4914 -- For standard check name, we can do a direct computation
4916 if N in First_Check_Name .. Last_Check_Name then
4917 return Check_Id (N - (First_Check_Name - 1));
4919 -- For non-standard names added by pragma Check_Name, search table
4922 for J in All_Checks + 1 .. Check_Names.Last loop
4923 if Check_Names.Table (J) = N then
4929 -- No matching name found
4934 ---------------------
4935 -- Get_Discriminal --
4936 ---------------------
4938 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
4939 Loc : constant Source_Ptr := Sloc (E);
4944 -- The bound can be a bona fide parameter of a protected operation,
4945 -- rather than a prival encoded as an in-parameter.
4947 if No (Discriminal_Link (Entity (Bound))) then
4951 -- Climb the scope stack looking for an enclosing protected type. If
4952 -- we run out of scopes, return the bound itself.
4955 while Present (Sc) loop
4956 if Sc = Standard_Standard then
4959 elsif Ekind (Sc) = E_Protected_Type then
4966 D := First_Discriminant (Sc);
4967 while Present (D) loop
4968 if Chars (D) = Chars (Bound) then
4969 return New_Occurrence_Of (Discriminal (D), Loc);
4972 Next_Discriminant (D);
4976 end Get_Discriminal;
4978 ----------------------
4979 -- Get_Range_Checks --
4980 ----------------------
4982 function Get_Range_Checks
4984 Target_Typ : Entity_Id;
4985 Source_Typ : Entity_Id := Empty;
4986 Warn_Node : Node_Id := Empty) return Check_Result
4989 return Selected_Range_Checks
4990 (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
4991 end Get_Range_Checks;
4997 function Guard_Access
5000 Ck_Node : Node_Id) return Node_Id
5003 if Nkind (Cond) = N_Or_Else then
5004 Set_Paren_Count (Cond, 1);
5007 if Nkind (Ck_Node) = N_Allocator then
5014 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
5015 Right_Opnd => Make_Null (Loc)),
5016 Right_Opnd => Cond);
5020 -----------------------------
5021 -- Index_Checks_Suppressed --
5022 -----------------------------
5024 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
5026 if Present (E) and then Checks_May_Be_Suppressed (E) then
5027 return Is_Check_Suppressed (E, Index_Check);
5029 return Scope_Suppress (Index_Check);
5031 end Index_Checks_Suppressed;
5037 procedure Initialize is
5039 for J in Determine_Range_Cache_N'Range loop
5040 Determine_Range_Cache_N (J) := Empty;
5045 for J in Int range 1 .. All_Checks loop
5046 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
5050 -------------------------
5051 -- Insert_Range_Checks --
5052 -------------------------
5054 procedure Insert_Range_Checks
5055 (Checks : Check_Result;
5057 Suppress_Typ : Entity_Id;
5058 Static_Sloc : Source_Ptr := No_Location;
5059 Flag_Node : Node_Id := Empty;
5060 Do_Before : Boolean := False)
5062 Internal_Flag_Node : Node_Id := Flag_Node;
5063 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
5065 Check_Node : Node_Id;
5066 Checks_On : constant Boolean :=
5067 (not Index_Checks_Suppressed (Suppress_Typ))
5069 (not Range_Checks_Suppressed (Suppress_Typ));
5072 -- For now we just return if Checks_On is false, however this should be
5073 -- enhanced to check for an always True value in the condition and to
5074 -- generate a compilation warning???
5076 if not Expander_Active or else not Checks_On then
5080 if Static_Sloc = No_Location then
5081 Internal_Static_Sloc := Sloc (Node);
5084 if No (Flag_Node) then
5085 Internal_Flag_Node := Node;
5088 for J in 1 .. 2 loop
5089 exit when No (Checks (J));
5091 if Nkind (Checks (J)) = N_Raise_Constraint_Error
5092 and then Present (Condition (Checks (J)))
5094 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
5095 Check_Node := Checks (J);
5096 Mark_Rewrite_Insertion (Check_Node);
5099 Insert_Before_And_Analyze (Node, Check_Node);
5101 Insert_After_And_Analyze (Node, Check_Node);
5104 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
5109 Make_Raise_Constraint_Error (Internal_Static_Sloc,
5110 Reason => CE_Range_Check_Failed);
5111 Mark_Rewrite_Insertion (Check_Node);
5114 Insert_Before_And_Analyze (Node, Check_Node);
5116 Insert_After_And_Analyze (Node, Check_Node);
5120 end Insert_Range_Checks;
5122 ------------------------
5123 -- Insert_Valid_Check --
5124 ------------------------
5126 procedure Insert_Valid_Check (Expr : Node_Id) is
5127 Loc : constant Source_Ptr := Sloc (Expr);
5131 -- Do not insert if checks off, or if not checking validity or
5132 -- if expression is known to be valid
5134 if not Validity_Checks_On
5135 or else Range_Or_Validity_Checks_Suppressed (Expr)
5136 or else Expr_Known_Valid (Expr)
5141 -- If we have a checked conversion, then validity check applies to
5142 -- the expression inside the conversion, not the result, since if
5143 -- the expression inside is valid, then so is the conversion result.
5146 while Nkind (Exp) = N_Type_Conversion loop
5147 Exp := Expression (Exp);
5150 -- We are about to insert the validity check for Exp. We save and
5151 -- reset the Do_Range_Check flag over this validity check, and then
5152 -- put it back for the final original reference (Exp may be rewritten).
5155 DRC : constant Boolean := Do_Range_Check (Exp);
5158 Set_Do_Range_Check (Exp, False);
5160 -- Force evaluation to avoid multiple reads for atomic/volatile
5162 if Is_Entity_Name (Exp)
5163 and then Is_Volatile (Entity (Exp))
5165 Force_Evaluation (Exp, Name_Req => True);
5168 -- Insert the validity check. Note that we do this with validity
5169 -- checks turned off, to avoid recursion, we do not want validity
5170 -- checks on the validity checking code itself!
5174 Make_Raise_Constraint_Error (Loc,
5178 Make_Attribute_Reference (Loc,
5180 Duplicate_Subexpr_No_Checks (Exp, Name_Req => True),
5181 Attribute_Name => Name_Valid)),
5182 Reason => CE_Invalid_Data),
5183 Suppress => Validity_Check);
5185 -- If the expression is a a reference to an element of a bit-packed
5186 -- array, then it is rewritten as a renaming declaration. If the
5187 -- expression is an actual in a call, it has not been expanded,
5188 -- waiting for the proper point at which to do it. The same happens
5189 -- with renamings, so that we have to force the expansion now. This
5190 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
5193 if Is_Entity_Name (Exp)
5194 and then Nkind (Parent (Entity (Exp))) =
5195 N_Object_Renaming_Declaration
5198 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
5200 if Nkind (Old_Exp) = N_Indexed_Component
5201 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
5203 Expand_Packed_Element_Reference (Old_Exp);
5208 -- Put back the Do_Range_Check flag on the resulting (possibly
5209 -- rewritten) expression.
5211 -- Note: it might be thought that a validity check is not required
5212 -- when a range check is present, but that's not the case, because
5213 -- the back end is allowed to assume for the range check that the
5214 -- operand is within its declared range (an assumption that validity
5215 -- checking is all about NOT assuming!)
5217 -- Note: no need to worry about Possible_Local_Raise here, it will
5218 -- already have been called if original node has Do_Range_Check set.
5220 Set_Do_Range_Check (Exp, DRC);
5222 end Insert_Valid_Check;
5224 ----------------------------------
5225 -- Install_Null_Excluding_Check --
5226 ----------------------------------
5228 procedure Install_Null_Excluding_Check (N : Node_Id) is
5229 Loc : constant Source_Ptr := Sloc (N);
5230 Typ : constant Entity_Id := Etype (N);
5232 function Safe_To_Capture_In_Parameter_Value return Boolean;
5233 -- Determines if it is safe to capture Known_Non_Null status for an
5234 -- the entity referenced by node N. The caller ensures that N is indeed
5235 -- an entity name. It is safe to capture the non-null status for an IN
5236 -- parameter when the reference occurs within a declaration that is sure
5237 -- to be executed as part of the declarative region.
5239 procedure Mark_Non_Null;
5240 -- After installation of check, if the node in question is an entity
5241 -- name, then mark this entity as non-null if possible.
5243 function Safe_To_Capture_In_Parameter_Value return Boolean is
5244 E : constant Entity_Id := Entity (N);
5245 S : constant Entity_Id := Current_Scope;
5249 if Ekind (E) /= E_In_Parameter then
5253 -- Two initial context checks. We must be inside a subprogram body
5254 -- with declarations and reference must not appear in nested scopes.
5256 if (Ekind (S) /= E_Function and then Ekind (S) /= E_Procedure)
5257 or else Scope (E) /= S
5262 S_Par := Parent (Parent (S));
5264 if Nkind (S_Par) /= N_Subprogram_Body
5265 or else No (Declarations (S_Par))
5275 -- Retrieve the declaration node of N (if any). Note that N
5276 -- may be a part of a complex initialization expression.
5280 while Present (P) loop
5282 -- If we have a short circuit form, and we are within the right
5283 -- hand expression, we return false, since the right hand side
5284 -- is not guaranteed to be elaborated.
5286 if Nkind (P) in N_Short_Circuit
5287 and then N = Right_Opnd (P)
5292 -- Similarly, if we are in a conditional expression and not
5293 -- part of the condition, then we return False, since neither
5294 -- the THEN or ELSE expressions will always be elaborated.
5296 if Nkind (P) = N_Conditional_Expression
5297 and then N /= First (Expressions (P))
5302 -- While traversing the parent chain, we find that N
5303 -- belongs to a statement, thus it may never appear in
5304 -- a declarative region.
5306 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
5307 or else Nkind (P) = N_Procedure_Call_Statement
5312 -- If we are at a declaration, record it and exit
5314 if Nkind (P) in N_Declaration
5315 and then Nkind (P) not in N_Subprogram_Specification
5328 return List_Containing (N_Decl) = Declarations (S_Par);
5330 end Safe_To_Capture_In_Parameter_Value;
5336 procedure Mark_Non_Null is
5338 -- Only case of interest is if node N is an entity name
5340 if Is_Entity_Name (N) then
5342 -- For sure, we want to clear an indication that this is known to
5343 -- be null, since if we get past this check, it definitely is not!
5345 Set_Is_Known_Null (Entity (N), False);
5347 -- We can mark the entity as known to be non-null if either it is
5348 -- safe to capture the value, or in the case of an IN parameter,
5349 -- which is a constant, if the check we just installed is in the
5350 -- declarative region of the subprogram body. In this latter case,
5351 -- a check is decisive for the rest of the body if the expression
5352 -- is sure to be elaborated, since we know we have to elaborate
5353 -- all declarations before executing the body.
5355 -- Couldn't this always be part of Safe_To_Capture_Value ???
5357 if Safe_To_Capture_Value (N, Entity (N))
5358 or else Safe_To_Capture_In_Parameter_Value
5360 Set_Is_Known_Non_Null (Entity (N));
5365 -- Start of processing for Install_Null_Excluding_Check
5368 pragma Assert (Is_Access_Type (Typ));
5370 -- No check inside a generic (why not???)
5372 if Inside_A_Generic then
5376 -- No check needed if known to be non-null
5378 if Known_Non_Null (N) then
5382 -- If known to be null, here is where we generate a compile time check
5384 if Known_Null (N) then
5386 -- Avoid generating warning message inside init procs
5388 if not Inside_Init_Proc then
5389 Apply_Compile_Time_Constraint_Error
5391 "null value not allowed here?",
5392 CE_Access_Check_Failed);
5395 Make_Raise_Constraint_Error (Loc,
5396 Reason => CE_Access_Check_Failed));
5403 -- If entity is never assigned, for sure a warning is appropriate
5405 if Is_Entity_Name (N) then
5406 Check_Unset_Reference (N);
5409 -- No check needed if checks are suppressed on the range. Note that we
5410 -- don't set Is_Known_Non_Null in this case (we could legitimately do
5411 -- so, since the program is erroneous, but we don't like to casually
5412 -- propagate such conclusions from erroneosity).
5414 if Access_Checks_Suppressed (Typ) then
5418 -- No check needed for access to concurrent record types generated by
5419 -- the expander. This is not just an optimization (though it does indeed
5420 -- remove junk checks). It also avoids generation of junk warnings.
5422 if Nkind (N) in N_Has_Chars
5423 and then Chars (N) = Name_uObject
5424 and then Is_Concurrent_Record_Type
5425 (Directly_Designated_Type (Etype (N)))
5430 -- Otherwise install access check
5433 Make_Raise_Constraint_Error (Loc,
5436 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
5437 Right_Opnd => Make_Null (Loc)),
5438 Reason => CE_Access_Check_Failed));
5441 end Install_Null_Excluding_Check;
5443 --------------------------
5444 -- Install_Static_Check --
5445 --------------------------
5447 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
5448 Stat : constant Boolean := Is_Static_Expression (R_Cno);
5449 Typ : constant Entity_Id := Etype (R_Cno);
5453 Make_Raise_Constraint_Error (Loc,
5454 Reason => CE_Range_Check_Failed));
5455 Set_Analyzed (R_Cno);
5456 Set_Etype (R_Cno, Typ);
5457 Set_Raises_Constraint_Error (R_Cno);
5458 Set_Is_Static_Expression (R_Cno, Stat);
5460 -- Now deal with possible local raise handling
5462 Possible_Local_Raise (R_Cno, Standard_Constraint_Error);
5463 end Install_Static_Check;
5465 ---------------------
5466 -- Kill_All_Checks --
5467 ---------------------
5469 procedure Kill_All_Checks is
5471 if Debug_Flag_CC then
5472 w ("Kill_All_Checks");
5475 -- We reset the number of saved checks to zero, and also modify all
5476 -- stack entries for statement ranges to indicate that the number of
5477 -- checks at each level is now zero.
5479 Num_Saved_Checks := 0;
5481 -- Note: the Int'Min here avoids any possibility of J being out of
5482 -- range when called from e.g. Conditional_Statements_Begin.
5484 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
5485 Saved_Checks_Stack (J) := 0;
5487 end Kill_All_Checks;
5493 procedure Kill_Checks (V : Entity_Id) is
5495 if Debug_Flag_CC then
5496 w ("Kill_Checks for entity", Int (V));
5499 for J in 1 .. Num_Saved_Checks loop
5500 if Saved_Checks (J).Entity = V then
5501 if Debug_Flag_CC then
5502 w (" Checks killed for saved check ", J);
5505 Saved_Checks (J).Killed := True;
5510 ------------------------------
5511 -- Length_Checks_Suppressed --
5512 ------------------------------
5514 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
5516 if Present (E) and then Checks_May_Be_Suppressed (E) then
5517 return Is_Check_Suppressed (E, Length_Check);
5519 return Scope_Suppress (Length_Check);
5521 end Length_Checks_Suppressed;
5523 --------------------------------
5524 -- Overflow_Checks_Suppressed --
5525 --------------------------------
5527 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
5529 if Present (E) and then Checks_May_Be_Suppressed (E) then
5530 return Is_Check_Suppressed (E, Overflow_Check);
5532 return Scope_Suppress (Overflow_Check);
5534 end Overflow_Checks_Suppressed;
5536 -----------------------------
5537 -- Range_Checks_Suppressed --
5538 -----------------------------
5540 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
5544 -- Note: for now we always suppress range checks on Vax float types,
5545 -- since Gigi does not know how to generate these checks.
5547 if Vax_Float (E) then
5549 elsif Kill_Range_Checks (E) then
5551 elsif Checks_May_Be_Suppressed (E) then
5552 return Is_Check_Suppressed (E, Range_Check);
5556 return Scope_Suppress (Range_Check);
5557 end Range_Checks_Suppressed;
5559 -----------------------------------------
5560 -- Range_Or_Validity_Checks_Suppressed --
5561 -----------------------------------------
5563 -- Note: the coding would be simpler here if we simply made appropriate
5564 -- calls to Range/Validity_Checks_Suppressed, but that would result in
5565 -- duplicated checks which we prefer to avoid.
5567 function Range_Or_Validity_Checks_Suppressed
5568 (Expr : Node_Id) return Boolean
5571 -- Immediate return if scope checks suppressed for either check
5573 if Scope_Suppress (Range_Check) or Scope_Suppress (Validity_Check) then
5577 -- If no expression, that's odd, decide that checks are suppressed,
5578 -- since we don't want anyone trying to do checks in this case, which
5579 -- is most likely the result of some other error.
5585 -- Expression is present, so perform suppress checks on type
5588 Typ : constant Entity_Id := Etype (Expr);
5590 if Vax_Float (Typ) then
5592 elsif Checks_May_Be_Suppressed (Typ)
5593 and then (Is_Check_Suppressed (Typ, Range_Check)
5595 Is_Check_Suppressed (Typ, Validity_Check))
5601 -- If expression is an entity name, perform checks on this entity
5603 if Is_Entity_Name (Expr) then
5605 Ent : constant Entity_Id := Entity (Expr);
5607 if Checks_May_Be_Suppressed (Ent) then
5608 return Is_Check_Suppressed (Ent, Range_Check)
5609 or else Is_Check_Suppressed (Ent, Validity_Check);
5614 -- If we fall through, no checks suppressed
5617 end Range_Or_Validity_Checks_Suppressed;
5623 procedure Remove_Checks (Expr : Node_Id) is
5624 function Process (N : Node_Id) return Traverse_Result;
5625 -- Process a single node during the traversal
5627 procedure Traverse is new Traverse_Proc (Process);
5628 -- The traversal procedure itself
5634 function Process (N : Node_Id) return Traverse_Result is
5636 if Nkind (N) not in N_Subexpr then
5640 Set_Do_Range_Check (N, False);
5644 Traverse (Left_Opnd (N));
5647 when N_Attribute_Reference =>
5648 Set_Do_Overflow_Check (N, False);
5650 when N_Function_Call =>
5651 Set_Do_Tag_Check (N, False);
5654 Set_Do_Overflow_Check (N, False);
5658 Set_Do_Division_Check (N, False);
5661 Set_Do_Length_Check (N, False);
5664 Set_Do_Division_Check (N, False);
5667 Set_Do_Length_Check (N, False);
5670 Set_Do_Division_Check (N, False);
5673 Set_Do_Length_Check (N, False);
5680 Traverse (Left_Opnd (N));
5683 when N_Selected_Component =>
5684 Set_Do_Discriminant_Check (N, False);
5686 when N_Type_Conversion =>
5687 Set_Do_Length_Check (N, False);
5688 Set_Do_Tag_Check (N, False);
5689 Set_Do_Overflow_Check (N, False);
5698 -- Start of processing for Remove_Checks
5704 ----------------------------
5705 -- Selected_Length_Checks --
5706 ----------------------------
5708 function Selected_Length_Checks
5710 Target_Typ : Entity_Id;
5711 Source_Typ : Entity_Id;
5712 Warn_Node : Node_Id) return Check_Result
5714 Loc : constant Source_Ptr := Sloc (Ck_Node);
5717 Expr_Actual : Node_Id;
5719 Cond : Node_Id := Empty;
5720 Do_Access : Boolean := False;
5721 Wnode : Node_Id := Warn_Node;
5722 Ret_Result : Check_Result := (Empty, Empty);
5723 Num_Checks : Natural := 0;
5725 procedure Add_Check (N : Node_Id);
5726 -- Adds the action given to Ret_Result if N is non-Empty
5728 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
5729 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
5730 -- Comments required ???
5732 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
5733 -- True for equal literals and for nodes that denote the same constant
5734 -- entity, even if its value is not a static constant. This includes the
5735 -- case of a discriminal reference within an init proc. Removes some
5736 -- obviously superfluous checks.
5738 function Length_E_Cond
5739 (Exptyp : Entity_Id;
5741 Indx : Nat) return Node_Id;
5742 -- Returns expression to compute:
5743 -- Typ'Length /= Exptyp'Length
5745 function Length_N_Cond
5748 Indx : Nat) return Node_Id;
5749 -- Returns expression to compute:
5750 -- Typ'Length /= Expr'Length
5756 procedure Add_Check (N : Node_Id) is
5760 -- For now, ignore attempt to place more than 2 checks ???
5762 if Num_Checks = 2 then
5766 pragma Assert (Num_Checks <= 1);
5767 Num_Checks := Num_Checks + 1;
5768 Ret_Result (Num_Checks) := N;
5776 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
5777 SE : constant Entity_Id := Scope (E);
5779 E1 : Entity_Id := E;
5782 if Ekind (Scope (E)) = E_Record_Type
5783 and then Has_Discriminants (Scope (E))
5785 N := Build_Discriminal_Subtype_Of_Component (E);
5788 Insert_Action (Ck_Node, N);
5789 E1 := Defining_Identifier (N);
5793 if Ekind (E1) = E_String_Literal_Subtype then
5795 Make_Integer_Literal (Loc,
5796 Intval => String_Literal_Length (E1));
5798 elsif SE /= Standard_Standard
5799 and then Ekind (Scope (SE)) = E_Protected_Type
5800 and then Has_Discriminants (Scope (SE))
5801 and then Has_Completion (Scope (SE))
5802 and then not Inside_Init_Proc
5804 -- If the type whose length is needed is a private component
5805 -- constrained by a discriminant, we must expand the 'Length
5806 -- attribute into an explicit computation, using the discriminal
5807 -- of the current protected operation. This is because the actual
5808 -- type of the prival is constructed after the protected opera-
5809 -- tion has been fully expanded.
5812 Indx_Type : Node_Id;
5815 Do_Expand : Boolean := False;
5818 Indx_Type := First_Index (E);
5820 for J in 1 .. Indx - 1 loop
5821 Next_Index (Indx_Type);
5824 Get_Index_Bounds (Indx_Type, Lo, Hi);
5826 if Nkind (Lo) = N_Identifier
5827 and then Ekind (Entity (Lo)) = E_In_Parameter
5829 Lo := Get_Discriminal (E, Lo);
5833 if Nkind (Hi) = N_Identifier
5834 and then Ekind (Entity (Hi)) = E_In_Parameter
5836 Hi := Get_Discriminal (E, Hi);
5841 if not Is_Entity_Name (Lo) then
5842 Lo := Duplicate_Subexpr_No_Checks (Lo);
5845 if not Is_Entity_Name (Hi) then
5846 Lo := Duplicate_Subexpr_No_Checks (Hi);
5852 Make_Op_Subtract (Loc,
5856 Right_Opnd => Make_Integer_Literal (Loc, 1));
5861 Make_Attribute_Reference (Loc,
5862 Attribute_Name => Name_Length,
5864 New_Occurrence_Of (E1, Loc));
5867 Set_Expressions (N, New_List (
5868 Make_Integer_Literal (Loc, Indx)));
5877 Make_Attribute_Reference (Loc,
5878 Attribute_Name => Name_Length,
5880 New_Occurrence_Of (E1, Loc));
5883 Set_Expressions (N, New_List (
5884 Make_Integer_Literal (Loc, Indx)));
5895 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
5898 Make_Attribute_Reference (Loc,
5899 Attribute_Name => Name_Length,
5901 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
5902 Expressions => New_List (
5903 Make_Integer_Literal (Loc, Indx)));
5910 function Length_E_Cond
5911 (Exptyp : Entity_Id;
5913 Indx : Nat) return Node_Id
5918 Left_Opnd => Get_E_Length (Typ, Indx),
5919 Right_Opnd => Get_E_Length (Exptyp, Indx));
5926 function Length_N_Cond
5929 Indx : Nat) return Node_Id
5934 Left_Opnd => Get_E_Length (Typ, Indx),
5935 Right_Opnd => Get_N_Length (Expr, Indx));
5942 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
5945 (Nkind (L) = N_Integer_Literal
5946 and then Nkind (R) = N_Integer_Literal
5947 and then Intval (L) = Intval (R))
5951 and then Ekind (Entity (L)) = E_Constant
5952 and then ((Is_Entity_Name (R)
5953 and then Entity (L) = Entity (R))
5955 (Nkind (R) = N_Type_Conversion
5956 and then Is_Entity_Name (Expression (R))
5957 and then Entity (L) = Entity (Expression (R)))))
5961 and then Ekind (Entity (R)) = E_Constant
5962 and then Nkind (L) = N_Type_Conversion
5963 and then Is_Entity_Name (Expression (L))
5964 and then Entity (R) = Entity (Expression (L)))
5968 and then Is_Entity_Name (R)
5969 and then Entity (L) = Entity (R)
5970 and then Ekind (Entity (L)) = E_In_Parameter
5971 and then Inside_Init_Proc);
5974 -- Start of processing for Selected_Length_Checks
5977 if not Expander_Active then
5981 if Target_Typ = Any_Type
5982 or else Target_Typ = Any_Composite
5983 or else Raises_Constraint_Error (Ck_Node)
5992 T_Typ := Target_Typ;
5994 if No (Source_Typ) then
5995 S_Typ := Etype (Ck_Node);
5997 S_Typ := Source_Typ;
6000 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6004 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6005 S_Typ := Designated_Type (S_Typ);
6006 T_Typ := Designated_Type (T_Typ);
6009 -- A simple optimization for the null case
6011 if Known_Null (Ck_Node) then
6016 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6017 if Is_Constrained (T_Typ) then
6019 -- The checking code to be generated will freeze the
6020 -- corresponding array type. However, we must freeze the
6021 -- type now, so that the freeze node does not appear within
6022 -- the generated condional expression, but ahead of it.
6024 Freeze_Before (Ck_Node, T_Typ);
6026 Expr_Actual := Get_Referenced_Object (Ck_Node);
6027 Exptyp := Get_Actual_Subtype (Ck_Node);
6029 if Is_Access_Type (Exptyp) then
6030 Exptyp := Designated_Type (Exptyp);
6033 -- String_Literal case. This needs to be handled specially be-
6034 -- cause no index types are available for string literals. The
6035 -- condition is simply:
6037 -- T_Typ'Length = string-literal-length
6039 if Nkind (Expr_Actual) = N_String_Literal
6040 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
6044 Left_Opnd => Get_E_Length (T_Typ, 1),
6046 Make_Integer_Literal (Loc,
6048 String_Literal_Length (Etype (Expr_Actual))));
6050 -- General array case. Here we have a usable actual subtype for
6051 -- the expression, and the condition is built from the two types
6054 -- T_Typ'Length /= Exptyp'Length or else
6055 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
6056 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
6059 elsif Is_Constrained (Exptyp) then
6061 Ndims : constant Nat := Number_Dimensions (T_Typ);
6074 -- At the library level, we need to ensure that the type of
6075 -- the object is elaborated before the check itself is
6076 -- emitted. This is only done if the object is in the
6077 -- current compilation unit, otherwise the type is frozen
6078 -- and elaborated in its unit.
6080 if Is_Itype (Exptyp)
6082 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
6084 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
6085 and then In_Open_Scopes (Scope (Exptyp))
6087 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
6088 Set_Itype (Ref_Node, Exptyp);
6089 Insert_Action (Ck_Node, Ref_Node);
6092 L_Index := First_Index (T_Typ);
6093 R_Index := First_Index (Exptyp);
6095 for Indx in 1 .. Ndims loop
6096 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6098 Nkind (R_Index) = N_Raise_Constraint_Error)
6100 Get_Index_Bounds (L_Index, L_Low, L_High);
6101 Get_Index_Bounds (R_Index, R_Low, R_High);
6103 -- Deal with compile time length check. Note that we
6104 -- skip this in the access case, because the access
6105 -- value may be null, so we cannot know statically.
6108 and then Compile_Time_Known_Value (L_Low)
6109 and then Compile_Time_Known_Value (L_High)
6110 and then Compile_Time_Known_Value (R_Low)
6111 and then Compile_Time_Known_Value (R_High)
6113 if Expr_Value (L_High) >= Expr_Value (L_Low) then
6114 L_Length := Expr_Value (L_High) -
6115 Expr_Value (L_Low) + 1;
6117 L_Length := UI_From_Int (0);
6120 if Expr_Value (R_High) >= Expr_Value (R_Low) then
6121 R_Length := Expr_Value (R_High) -
6122 Expr_Value (R_Low) + 1;
6124 R_Length := UI_From_Int (0);
6127 if L_Length > R_Length then
6129 (Compile_Time_Constraint_Error
6130 (Wnode, "too few elements for}?", T_Typ));
6132 elsif L_Length < R_Length then
6134 (Compile_Time_Constraint_Error
6135 (Wnode, "too many elements for}?", T_Typ));
6138 -- The comparison for an individual index subtype
6139 -- is omitted if the corresponding index subtypes
6140 -- statically match, since the result is known to
6141 -- be true. Note that this test is worth while even
6142 -- though we do static evaluation, because non-static
6143 -- subtypes can statically match.
6146 Subtypes_Statically_Match
6147 (Etype (L_Index), Etype (R_Index))
6150 (Same_Bounds (L_Low, R_Low)
6151 and then Same_Bounds (L_High, R_High))
6154 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
6163 -- Handle cases where we do not get a usable actual subtype that
6164 -- is constrained. This happens for example in the function call
6165 -- and explicit dereference cases. In these cases, we have to get
6166 -- the length or range from the expression itself, making sure we
6167 -- do not evaluate it more than once.
6169 -- Here Ck_Node is the original expression, or more properly the
6170 -- result of applying Duplicate_Expr to the original tree, forcing
6171 -- the result to be a name.
6175 Ndims : constant Nat := Number_Dimensions (T_Typ);
6178 -- Build the condition for the explicit dereference case
6180 for Indx in 1 .. Ndims loop
6182 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
6189 -- Construct the test and insert into the tree
6191 if Present (Cond) then
6193 Cond := Guard_Access (Cond, Loc, Ck_Node);
6197 (Make_Raise_Constraint_Error (Loc,
6199 Reason => CE_Length_Check_Failed));
6203 end Selected_Length_Checks;
6205 ---------------------------
6206 -- Selected_Range_Checks --
6207 ---------------------------
6209 function Selected_Range_Checks
6211 Target_Typ : Entity_Id;
6212 Source_Typ : Entity_Id;
6213 Warn_Node : Node_Id) return Check_Result
6215 Loc : constant Source_Ptr := Sloc (Ck_Node);
6218 Expr_Actual : Node_Id;
6220 Cond : Node_Id := Empty;
6221 Do_Access : Boolean := False;
6222 Wnode : Node_Id := Warn_Node;
6223 Ret_Result : Check_Result := (Empty, Empty);
6224 Num_Checks : Integer := 0;
6226 procedure Add_Check (N : Node_Id);
6227 -- Adds the action given to Ret_Result if N is non-Empty
6229 function Discrete_Range_Cond
6231 Typ : Entity_Id) return Node_Id;
6232 -- Returns expression to compute:
6233 -- Low_Bound (Expr) < Typ'First
6235 -- High_Bound (Expr) > Typ'Last
6237 function Discrete_Expr_Cond
6239 Typ : Entity_Id) return Node_Id;
6240 -- Returns expression to compute:
6245 function Get_E_First_Or_Last
6248 Nam : Name_Id) return Node_Id;
6249 -- Returns expression to compute:
6250 -- E'First or E'Last
6252 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
6253 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
6254 -- Returns expression to compute:
6255 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
6257 function Range_E_Cond
6258 (Exptyp : Entity_Id;
6262 -- Returns expression to compute:
6263 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
6265 function Range_Equal_E_Cond
6266 (Exptyp : Entity_Id;
6268 Indx : Nat) return Node_Id;
6269 -- Returns expression to compute:
6270 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
6272 function Range_N_Cond
6275 Indx : Nat) return Node_Id;
6276 -- Return expression to compute:
6277 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
6283 procedure Add_Check (N : Node_Id) is
6287 -- For now, ignore attempt to place more than 2 checks ???
6289 if Num_Checks = 2 then
6293 pragma Assert (Num_Checks <= 1);
6294 Num_Checks := Num_Checks + 1;
6295 Ret_Result (Num_Checks) := N;
6299 -------------------------
6300 -- Discrete_Expr_Cond --
6301 -------------------------
6303 function Discrete_Expr_Cond
6305 Typ : Entity_Id) return Node_Id
6313 Convert_To (Base_Type (Typ),
6314 Duplicate_Subexpr_No_Checks (Expr)),
6316 Convert_To (Base_Type (Typ),
6317 Get_E_First_Or_Last (Typ, 0, Name_First))),
6322 Convert_To (Base_Type (Typ),
6323 Duplicate_Subexpr_No_Checks (Expr)),
6327 Get_E_First_Or_Last (Typ, 0, Name_Last))));
6328 end Discrete_Expr_Cond;
6330 -------------------------
6331 -- Discrete_Range_Cond --
6332 -------------------------
6334 function Discrete_Range_Cond
6336 Typ : Entity_Id) return Node_Id
6338 LB : Node_Id := Low_Bound (Expr);
6339 HB : Node_Id := High_Bound (Expr);
6341 Left_Opnd : Node_Id;
6342 Right_Opnd : Node_Id;
6345 if Nkind (LB) = N_Identifier
6346 and then Ekind (Entity (LB)) = E_Discriminant
6348 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6351 if Nkind (HB) = N_Identifier
6352 and then Ekind (Entity (HB)) = E_Discriminant
6354 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6361 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
6365 (Base_Type (Typ), Get_E_First_Or_Last (Typ, 0, Name_First)));
6367 if Base_Type (Typ) = Typ then
6370 elsif Compile_Time_Known_Value (High_Bound (Scalar_Range (Typ)))
6372 Compile_Time_Known_Value (High_Bound (Scalar_Range
6375 if Is_Floating_Point_Type (Typ) then
6376 if Expr_Value_R (High_Bound (Scalar_Range (Typ))) =
6377 Expr_Value_R (High_Bound (Scalar_Range (Base_Type (Typ))))
6383 if Expr_Value (High_Bound (Scalar_Range (Typ))) =
6384 Expr_Value (High_Bound (Scalar_Range (Base_Type (Typ))))
6395 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
6400 Get_E_First_Or_Last (Typ, 0, Name_Last)));
6402 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
6403 end Discrete_Range_Cond;
6405 -------------------------
6406 -- Get_E_First_Or_Last --
6407 -------------------------
6409 function Get_E_First_Or_Last
6412 Nam : Name_Id) return Node_Id
6420 if Is_Array_Type (E) then
6421 N := First_Index (E);
6423 for J in 2 .. Indx loop
6428 N := Scalar_Range (E);
6431 if Nkind (N) = N_Subtype_Indication then
6432 LB := Low_Bound (Range_Expression (Constraint (N)));
6433 HB := High_Bound (Range_Expression (Constraint (N)));
6435 elsif Is_Entity_Name (N) then
6436 LB := Type_Low_Bound (Etype (N));
6437 HB := Type_High_Bound (Etype (N));
6440 LB := Low_Bound (N);
6441 HB := High_Bound (N);
6444 if Nam = Name_First then
6450 if Nkind (Bound) = N_Identifier
6451 and then Ekind (Entity (Bound)) = E_Discriminant
6453 -- If this is a task discriminant, and we are the body, we must
6454 -- retrieve the corresponding body discriminal. This is another
6455 -- consequence of the early creation of discriminals, and the
6456 -- need to generate constraint checks before their declarations
6457 -- are made visible.
6459 if Is_Concurrent_Record_Type (Scope (Entity (Bound))) then
6461 Tsk : constant Entity_Id :=
6462 Corresponding_Concurrent_Type
6463 (Scope (Entity (Bound)));
6467 if In_Open_Scopes (Tsk)
6468 and then Has_Completion (Tsk)
6470 -- Find discriminant of original task, and use its
6471 -- current discriminal, which is the renaming within
6474 Disc := First_Discriminant (Tsk);
6475 while Present (Disc) loop
6476 if Chars (Disc) = Chars (Entity (Bound)) then
6477 Set_Scope (Discriminal (Disc), Tsk);
6478 return New_Occurrence_Of (Discriminal (Disc), Loc);
6481 Next_Discriminant (Disc);
6484 -- That loop should always succeed in finding a matching
6485 -- entry and returning. Fatal error if not.
6487 raise Program_Error;
6491 New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6495 return New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6498 elsif Nkind (Bound) = N_Identifier
6499 and then Ekind (Entity (Bound)) = E_In_Parameter
6500 and then not Inside_Init_Proc
6502 return Get_Discriminal (E, Bound);
6504 elsif Nkind (Bound) = N_Integer_Literal then
6505 return Make_Integer_Literal (Loc, Intval (Bound));
6507 -- Case of a bound rewritten to an N_Raise_Constraint_Error node
6508 -- because it is an out-of-range value. Duplicate_Subexpr cannot be
6509 -- called on this node because an N_Raise_Constraint_Error is not
6510 -- side effect free, and we may not assume that we are in the proper
6511 -- context to remove side effects on it at the point of reference.
6513 elsif Nkind (Bound) = N_Raise_Constraint_Error then
6514 return New_Copy_Tree (Bound);
6517 return Duplicate_Subexpr_No_Checks (Bound);
6519 end Get_E_First_Or_Last;
6525 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
6528 Make_Attribute_Reference (Loc,
6529 Attribute_Name => Name_First,
6531 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6532 Expressions => New_List (
6533 Make_Integer_Literal (Loc, Indx)));
6540 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
6543 Make_Attribute_Reference (Loc,
6544 Attribute_Name => Name_Last,
6546 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6547 Expressions => New_List (
6548 Make_Integer_Literal (Loc, Indx)));
6555 function Range_E_Cond
6556 (Exptyp : Entity_Id;
6558 Indx : Nat) return Node_Id
6565 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6566 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6570 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6571 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6574 ------------------------
6575 -- Range_Equal_E_Cond --
6576 ------------------------
6578 function Range_Equal_E_Cond
6579 (Exptyp : Entity_Id;
6581 Indx : Nat) return Node_Id
6588 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6589 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6592 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6593 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6594 end Range_Equal_E_Cond;
6600 function Range_N_Cond
6603 Indx : Nat) return Node_Id
6610 Left_Opnd => Get_N_First (Expr, Indx),
6611 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6615 Left_Opnd => Get_N_Last (Expr, Indx),
6616 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6619 -- Start of processing for Selected_Range_Checks
6622 if not Expander_Active then
6626 if Target_Typ = Any_Type
6627 or else Target_Typ = Any_Composite
6628 or else Raises_Constraint_Error (Ck_Node)
6637 T_Typ := Target_Typ;
6639 if No (Source_Typ) then
6640 S_Typ := Etype (Ck_Node);
6642 S_Typ := Source_Typ;
6645 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6649 -- The order of evaluating T_Typ before S_Typ seems to be critical
6650 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
6651 -- in, and since Node can be an N_Range node, it might be invalid.
6652 -- Should there be an assert check somewhere for taking the Etype of
6653 -- an N_Range node ???
6655 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6656 S_Typ := Designated_Type (S_Typ);
6657 T_Typ := Designated_Type (T_Typ);
6660 -- A simple optimization for the null case
6662 if Known_Null (Ck_Node) then
6667 -- For an N_Range Node, check for a null range and then if not
6668 -- null generate a range check action.
6670 if Nkind (Ck_Node) = N_Range then
6672 -- There's no point in checking a range against itself
6674 if Ck_Node = Scalar_Range (T_Typ) then
6679 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
6680 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
6681 Known_T_LB : constant Boolean := Compile_Time_Known_Value (T_LB);
6682 Known_T_HB : constant Boolean := Compile_Time_Known_Value (T_HB);
6684 LB : Node_Id := Low_Bound (Ck_Node);
6685 HB : Node_Id := High_Bound (Ck_Node);
6689 Null_Range : Boolean;
6690 Out_Of_Range_L : Boolean;
6691 Out_Of_Range_H : Boolean;
6694 -- Compute what is known at compile time
6696 if Known_T_LB and Known_T_HB then
6697 if Compile_Time_Known_Value (LB) then
6700 -- There's no point in checking that a bound is within its
6701 -- own range so pretend that it is known in this case. First
6702 -- deal with low bound.
6704 elsif Ekind (Etype (LB)) = E_Signed_Integer_Subtype
6705 and then Scalar_Range (Etype (LB)) = Scalar_Range (T_Typ)
6714 -- Likewise for the high bound
6716 if Compile_Time_Known_Value (HB) then
6719 elsif Ekind (Etype (HB)) = E_Signed_Integer_Subtype
6720 and then Scalar_Range (Etype (HB)) = Scalar_Range (T_Typ)
6730 -- Check for case where everything is static and we can do the
6731 -- check at compile time. This is skipped if we have an access
6732 -- type, since the access value may be null.
6734 -- ??? This code can be improved since you only need to know that
6735 -- the two respective bounds (LB & T_LB or HB & T_HB) are known at
6736 -- compile time to emit pertinent messages.
6738 if Known_T_LB and Known_T_HB and Known_LB and Known_HB
6741 -- Floating-point case
6743 if Is_Floating_Point_Type (S_Typ) then
6744 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
6746 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
6748 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
6751 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
6753 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
6755 -- Fixed or discrete type case
6758 Null_Range := Expr_Value (HB) < Expr_Value (LB);
6760 (Expr_Value (LB) < Expr_Value (T_LB))
6762 (Expr_Value (LB) > Expr_Value (T_HB));
6765 (Expr_Value (HB) > Expr_Value (T_HB))
6767 (Expr_Value (HB) < Expr_Value (T_LB));
6770 if not Null_Range then
6771 if Out_Of_Range_L then
6772 if No (Warn_Node) then
6774 (Compile_Time_Constraint_Error
6775 (Low_Bound (Ck_Node),
6776 "static value out of range of}?", T_Typ));
6780 (Compile_Time_Constraint_Error
6782 "static range out of bounds of}?", T_Typ));
6786 if Out_Of_Range_H then
6787 if No (Warn_Node) then
6789 (Compile_Time_Constraint_Error
6790 (High_Bound (Ck_Node),
6791 "static value out of range of}?", T_Typ));
6795 (Compile_Time_Constraint_Error
6797 "static range out of bounds of}?", T_Typ));
6804 LB : Node_Id := Low_Bound (Ck_Node);
6805 HB : Node_Id := High_Bound (Ck_Node);
6808 -- If either bound is a discriminant and we are within the
6809 -- record declaration, it is a use of the discriminant in a
6810 -- constraint of a component, and nothing can be checked
6811 -- here. The check will be emitted within the init proc.
6812 -- Before then, the discriminal has no real meaning.
6813 -- Similarly, if the entity is a discriminal, there is no
6814 -- check to perform yet.
6816 -- The same holds within a discriminated synchronized type,
6817 -- where the discriminant may constrain a component or an
6820 if Nkind (LB) = N_Identifier
6821 and then Denotes_Discriminant (LB, True)
6823 if Current_Scope = Scope (Entity (LB))
6824 or else Is_Concurrent_Type (Current_Scope)
6825 or else Ekind (Entity (LB)) /= E_Discriminant
6830 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6834 if Nkind (HB) = N_Identifier
6835 and then Denotes_Discriminant (HB, True)
6837 if Current_Scope = Scope (Entity (HB))
6838 or else Is_Concurrent_Type (Current_Scope)
6839 or else Ekind (Entity (HB)) /= E_Discriminant
6844 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6848 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
6849 Set_Paren_Count (Cond, 1);
6855 Left_Opnd => Duplicate_Subexpr_No_Checks (HB),
6856 Right_Opnd => Duplicate_Subexpr_No_Checks (LB)),
6857 Right_Opnd => Cond);
6862 elsif Is_Scalar_Type (S_Typ) then
6864 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
6865 -- except the above simply sets a flag in the node and lets
6866 -- gigi generate the check base on the Etype of the expression.
6867 -- Sometimes, however we want to do a dynamic check against an
6868 -- arbitrary target type, so we do that here.
6870 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
6871 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6873 -- For literals, we can tell if the constraint error will be
6874 -- raised at compile time, so we never need a dynamic check, but
6875 -- if the exception will be raised, then post the usual warning,
6876 -- and replace the literal with a raise constraint error
6877 -- expression. As usual, skip this for access types
6879 elsif Compile_Time_Known_Value (Ck_Node)
6880 and then not Do_Access
6883 LB : constant Node_Id := Type_Low_Bound (T_Typ);
6884 UB : constant Node_Id := Type_High_Bound (T_Typ);
6886 Out_Of_Range : Boolean;
6887 Static_Bounds : constant Boolean :=
6888 Compile_Time_Known_Value (LB)
6889 and Compile_Time_Known_Value (UB);
6892 -- Following range tests should use Sem_Eval routine ???
6894 if Static_Bounds then
6895 if Is_Floating_Point_Type (S_Typ) then
6897 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
6899 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
6901 -- Fixed or discrete type
6905 Expr_Value (Ck_Node) < Expr_Value (LB)
6907 Expr_Value (Ck_Node) > Expr_Value (UB);
6910 -- Bounds of the type are static and the literal is out of
6911 -- range so output a warning message.
6913 if Out_Of_Range then
6914 if No (Warn_Node) then
6916 (Compile_Time_Constraint_Error
6918 "static value out of range of}?", T_Typ));
6922 (Compile_Time_Constraint_Error
6924 "static value out of range of}?", T_Typ));
6929 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6933 -- Here for the case of a non-static expression, we need a runtime
6934 -- check unless the source type range is guaranteed to be in the
6935 -- range of the target type.
6938 if not In_Subrange_Of (S_Typ, T_Typ) then
6939 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6944 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6945 if Is_Constrained (T_Typ) then
6947 Expr_Actual := Get_Referenced_Object (Ck_Node);
6948 Exptyp := Get_Actual_Subtype (Expr_Actual);
6950 if Is_Access_Type (Exptyp) then
6951 Exptyp := Designated_Type (Exptyp);
6954 -- String_Literal case. This needs to be handled specially be-
6955 -- cause no index types are available for string literals. The
6956 -- condition is simply:
6958 -- T_Typ'Length = string-literal-length
6960 if Nkind (Expr_Actual) = N_String_Literal then
6963 -- General array case. Here we have a usable actual subtype for
6964 -- the expression, and the condition is built from the two types
6966 -- T_Typ'First < Exptyp'First or else
6967 -- T_Typ'Last > Exptyp'Last or else
6968 -- T_Typ'First(1) < Exptyp'First(1) or else
6969 -- T_Typ'Last(1) > Exptyp'Last(1) or else
6972 elsif Is_Constrained (Exptyp) then
6974 Ndims : constant Nat := Number_Dimensions (T_Typ);
6980 L_Index := First_Index (T_Typ);
6981 R_Index := First_Index (Exptyp);
6983 for Indx in 1 .. Ndims loop
6984 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6986 Nkind (R_Index) = N_Raise_Constraint_Error)
6988 -- Deal with compile time length check. Note that we
6989 -- skip this in the access case, because the access
6990 -- value may be null, so we cannot know statically.
6993 Subtypes_Statically_Match
6994 (Etype (L_Index), Etype (R_Index))
6996 -- If the target type is constrained then we
6997 -- have to check for exact equality of bounds
6998 -- (required for qualified expressions).
7000 if Is_Constrained (T_Typ) then
7003 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
7006 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
7016 -- Handle cases where we do not get a usable actual subtype that
7017 -- is constrained. This happens for example in the function call
7018 -- and explicit dereference cases. In these cases, we have to get
7019 -- the length or range from the expression itself, making sure we
7020 -- do not evaluate it more than once.
7022 -- Here Ck_Node is the original expression, or more properly the
7023 -- result of applying Duplicate_Expr to the original tree,
7024 -- forcing the result to be a name.
7028 Ndims : constant Nat := Number_Dimensions (T_Typ);
7031 -- Build the condition for the explicit dereference case
7033 for Indx in 1 .. Ndims loop
7035 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
7041 -- For a conversion to an unconstrained array type, generate an
7042 -- Action to check that the bounds of the source value are within
7043 -- the constraints imposed by the target type (RM 4.6(38)). No
7044 -- check is needed for a conversion to an access to unconstrained
7045 -- array type, as 4.6(24.15/2) requires the designated subtypes
7046 -- of the two access types to statically match.
7048 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
7049 and then not Do_Access
7052 Opnd_Index : Node_Id;
7053 Targ_Index : Node_Id;
7054 Opnd_Range : Node_Id;
7057 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
7058 Targ_Index := First_Index (T_Typ);
7059 while Present (Opnd_Index) loop
7061 -- If the index is a range, use its bounds. If it is an
7062 -- entity (as will be the case if it is a named subtype
7063 -- or an itype created for a slice) retrieve its range.
7065 if Is_Entity_Name (Opnd_Index)
7066 and then Is_Type (Entity (Opnd_Index))
7068 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
7070 Opnd_Range := Opnd_Index;
7073 if Nkind (Opnd_Range) = N_Range then
7075 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7076 Assume_Valid => True)
7079 (High_Bound (Opnd_Range), Etype (Targ_Index),
7080 Assume_Valid => True)
7084 -- If null range, no check needed
7087 Compile_Time_Known_Value (High_Bound (Opnd_Range))
7089 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
7091 Expr_Value (High_Bound (Opnd_Range)) <
7092 Expr_Value (Low_Bound (Opnd_Range))
7096 elsif Is_Out_Of_Range
7097 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7098 Assume_Valid => True)
7101 (High_Bound (Opnd_Range), Etype (Targ_Index),
7102 Assume_Valid => True)
7105 (Compile_Time_Constraint_Error
7106 (Wnode, "value out of range of}?", T_Typ));
7112 (Opnd_Range, Etype (Targ_Index)));
7116 Next_Index (Opnd_Index);
7117 Next_Index (Targ_Index);
7124 -- Construct the test and insert into the tree
7126 if Present (Cond) then
7128 Cond := Guard_Access (Cond, Loc, Ck_Node);
7132 (Make_Raise_Constraint_Error (Loc,
7134 Reason => CE_Range_Check_Failed));
7138 end Selected_Range_Checks;
7140 -------------------------------
7141 -- Storage_Checks_Suppressed --
7142 -------------------------------
7144 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
7146 if Present (E) and then Checks_May_Be_Suppressed (E) then
7147 return Is_Check_Suppressed (E, Storage_Check);
7149 return Scope_Suppress (Storage_Check);
7151 end Storage_Checks_Suppressed;
7153 ---------------------------
7154 -- Tag_Checks_Suppressed --
7155 ---------------------------
7157 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
7160 if Kill_Tag_Checks (E) then
7162 elsif Checks_May_Be_Suppressed (E) then
7163 return Is_Check_Suppressed (E, Tag_Check);
7167 return Scope_Suppress (Tag_Check);
7168 end Tag_Checks_Suppressed;
7170 --------------------------
7171 -- Validity_Check_Range --
7172 --------------------------
7174 procedure Validity_Check_Range (N : Node_Id) is
7176 if Validity_Checks_On and Validity_Check_Operands then
7177 if Nkind (N) = N_Range then
7178 Ensure_Valid (Low_Bound (N));
7179 Ensure_Valid (High_Bound (N));
7182 end Validity_Check_Range;
7184 --------------------------------
7185 -- Validity_Checks_Suppressed --
7186 --------------------------------
7188 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
7190 if Present (E) and then Checks_May_Be_Suppressed (E) then
7191 return Is_Check_Suppressed (E, Validity_Check);
7193 return Scope_Suppress (Validity_Check);
7195 end Validity_Checks_Suppressed;