1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2010, 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 : constant Entity_Id := Etype (N);
726 Rtyp : constant 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 -- Rewrite the conversion operand so that the original
819 -- node is retained, in order to avoid the warning for
820 -- redundant conversions in Resolve_Type_Conversion.
822 -- The above comment is uncomfortable. This seems like
823 -- an awkward covert channel, since there isno general
824 -- requirement in sinfo.ads or einfo.ads that requires
825 -- this rewrite. Instead, the issue seems to be that in
826 -- the old code, some node was incorrectly marked as
827 -- coming from source when it should not have been and/or
828 -- the warning code did not properly test the appropriate
829 -- Comes_From_Soure flag. ???
831 Rewrite (N, Relocate_Node (N));
833 Set_Etype (N, Target_Type);
835 Analyze_And_Resolve (Left_Opnd (N), Target_Type);
836 Analyze_And_Resolve (Right_Opnd (N), Target_Type);
838 -- Given that the target type is twice the size of the
839 -- source type, overflow is now impossible, so we can
840 -- safely kill the overflow check and return.
842 Set_Do_Overflow_Check (N, False);
850 -- Now see if an overflow check is required
853 Siz : constant Int := UI_To_Int (Esize (Rtyp));
854 Dsiz : constant Int := Siz * 2;
861 -- Skip check if back end does overflow checks, or the overflow flag
862 -- is not set anyway, or we are not doing code expansion, or the
863 -- parent node is a type conversion whose operand is an arithmetic
864 -- operation on signed integers on which the expander can promote
865 -- later the operands to type Integer (see Expand_N_Type_Conversion).
867 -- Special case CLI target, where arithmetic overflow checks can be
868 -- performed for integer and long_integer
870 if Backend_Overflow_Checks_On_Target
871 or else not Do_Overflow_Check (N)
872 or else not Expander_Active
873 or else (Present (Parent (N))
874 and then Nkind (Parent (N)) = N_Type_Conversion
875 and then Integer_Promotion_Possible (Parent (N)))
877 (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
882 -- Otherwise, generate the full general code for front end overflow
883 -- detection, which works by doing arithmetic in a larger type:
889 -- Typ (Checktyp (x) op Checktyp (y));
891 -- where Typ is the type of the original expression, and Checktyp is
892 -- an integer type of sufficient length to hold the largest possible
895 -- If the size of check type exceeds the size of Long_Long_Integer,
896 -- we use a different approach, expanding to:
898 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
900 -- where xxx is Add, Multiply or Subtract as appropriate
902 -- Find check type if one exists
904 if Dsiz <= Standard_Integer_Size then
905 Ctyp := Standard_Integer;
907 elsif Dsiz <= Standard_Long_Long_Integer_Size then
908 Ctyp := Standard_Long_Long_Integer;
910 -- No check type exists, use runtime call
913 if Nkind (N) = N_Op_Add then
914 Cent := RE_Add_With_Ovflo_Check;
916 elsif Nkind (N) = N_Op_Multiply then
917 Cent := RE_Multiply_With_Ovflo_Check;
920 pragma Assert (Nkind (N) = N_Op_Subtract);
921 Cent := RE_Subtract_With_Ovflo_Check;
926 Make_Function_Call (Loc,
927 Name => New_Reference_To (RTE (Cent), Loc),
928 Parameter_Associations => New_List (
929 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
930 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
932 Analyze_And_Resolve (N, Typ);
936 -- If we fall through, we have the case where we do the arithmetic
937 -- in the next higher type and get the check by conversion. In these
938 -- cases Ctyp is set to the type to be used as the check type.
940 Opnod := Relocate_Node (N);
942 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
945 Set_Etype (Opnd, Ctyp);
946 Set_Analyzed (Opnd, True);
947 Set_Left_Opnd (Opnod, Opnd);
949 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
952 Set_Etype (Opnd, Ctyp);
953 Set_Analyzed (Opnd, True);
954 Set_Right_Opnd (Opnod, Opnd);
956 -- The type of the operation changes to the base type of the check
957 -- type, and we reset the overflow check indication, since clearly no
958 -- overflow is possible now that we are using a double length type.
959 -- We also set the Analyzed flag to avoid a recursive attempt to
962 Set_Etype (Opnod, Base_Type (Ctyp));
963 Set_Do_Overflow_Check (Opnod, False);
964 Set_Analyzed (Opnod, True);
966 -- Now build the outer conversion
968 Opnd := OK_Convert_To (Typ, Opnod);
970 Set_Etype (Opnd, Typ);
972 -- In the discrete type case, we directly generate the range check
973 -- for the outer operand. This range check will implement the
974 -- required overflow check.
976 if Is_Discrete_Type (Typ) then
979 (Expression (N), Typ, CE_Overflow_Check_Failed);
981 -- For other types, we enable overflow checking on the conversion,
982 -- after setting the node as analyzed to prevent recursive attempts
983 -- to expand the conversion node.
986 Set_Analyzed (Opnd, True);
987 Enable_Overflow_Check (Opnd);
992 when RE_Not_Available =>
995 end Apply_Arithmetic_Overflow_Check;
997 ----------------------------
998 -- Apply_Constraint_Check --
999 ----------------------------
1001 procedure Apply_Constraint_Check
1004 No_Sliding : Boolean := False)
1006 Desig_Typ : Entity_Id;
1009 if Inside_A_Generic then
1012 elsif Is_Scalar_Type (Typ) then
1013 Apply_Scalar_Range_Check (N, Typ);
1015 elsif Is_Array_Type (Typ) then
1017 -- A useful optimization: an aggregate with only an others clause
1018 -- always has the right bounds.
1020 if Nkind (N) = N_Aggregate
1021 and then No (Expressions (N))
1023 (First (Choices (First (Component_Associations (N)))))
1029 if Is_Constrained (Typ) then
1030 Apply_Length_Check (N, Typ);
1033 Apply_Range_Check (N, Typ);
1036 Apply_Range_Check (N, Typ);
1039 elsif (Is_Record_Type (Typ)
1040 or else Is_Private_Type (Typ))
1041 and then Has_Discriminants (Base_Type (Typ))
1042 and then Is_Constrained (Typ)
1044 Apply_Discriminant_Check (N, Typ);
1046 elsif Is_Access_Type (Typ) then
1048 Desig_Typ := Designated_Type (Typ);
1050 -- No checks necessary if expression statically null
1052 if Known_Null (N) then
1053 if Can_Never_Be_Null (Typ) then
1054 Install_Null_Excluding_Check (N);
1057 -- No sliding possible on access to arrays
1059 elsif Is_Array_Type (Desig_Typ) then
1060 if Is_Constrained (Desig_Typ) then
1061 Apply_Length_Check (N, Typ);
1064 Apply_Range_Check (N, Typ);
1066 elsif Has_Discriminants (Base_Type (Desig_Typ))
1067 and then Is_Constrained (Desig_Typ)
1069 Apply_Discriminant_Check (N, Typ);
1072 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1073 -- this check if the constraint node is illegal, as shown by having
1074 -- an error posted. This additional guard prevents cascaded errors
1075 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1077 if Can_Never_Be_Null (Typ)
1078 and then not Can_Never_Be_Null (Etype (N))
1079 and then not Error_Posted (N)
1081 Install_Null_Excluding_Check (N);
1084 end Apply_Constraint_Check;
1086 ------------------------------
1087 -- Apply_Discriminant_Check --
1088 ------------------------------
1090 procedure Apply_Discriminant_Check
1093 Lhs : Node_Id := Empty)
1095 Loc : constant Source_Ptr := Sloc (N);
1096 Do_Access : constant Boolean := Is_Access_Type (Typ);
1097 S_Typ : Entity_Id := Etype (N);
1101 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean;
1102 -- A heap object with an indefinite subtype is constrained by its
1103 -- initial value, and assigning to it requires a constraint_check.
1104 -- The target may be an explicit dereference, or a renaming of one.
1106 function Is_Aliased_Unconstrained_Component return Boolean;
1107 -- It is possible for an aliased component to have a nominal
1108 -- unconstrained subtype (through instantiation). If this is a
1109 -- discriminated component assigned in the expansion of an aggregate
1110 -- in an initialization, the check must be suppressed. This unusual
1111 -- situation requires a predicate of its own.
1113 ----------------------------------
1114 -- Denotes_Explicit_Dereference --
1115 ----------------------------------
1117 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean is
1120 Nkind (Obj) = N_Explicit_Dereference
1122 (Is_Entity_Name (Obj)
1123 and then Present (Renamed_Object (Entity (Obj)))
1124 and then Nkind (Renamed_Object (Entity (Obj))) =
1125 N_Explicit_Dereference);
1126 end Denotes_Explicit_Dereference;
1128 ----------------------------------------
1129 -- Is_Aliased_Unconstrained_Component --
1130 ----------------------------------------
1132 function Is_Aliased_Unconstrained_Component return Boolean is
1137 if Nkind (Lhs) /= N_Selected_Component then
1140 Comp := Entity (Selector_Name (Lhs));
1141 Pref := Prefix (Lhs);
1144 if Ekind (Comp) /= E_Component
1145 or else not Is_Aliased (Comp)
1150 return not Comes_From_Source (Pref)
1151 and then In_Instance
1152 and then not Is_Constrained (Etype (Comp));
1153 end Is_Aliased_Unconstrained_Component;
1155 -- Start of processing for Apply_Discriminant_Check
1159 T_Typ := Designated_Type (Typ);
1164 -- Nothing to do if discriminant checks are suppressed or else no code
1165 -- is to be generated
1167 if not Expander_Active
1168 or else Discriminant_Checks_Suppressed (T_Typ)
1173 -- No discriminant checks necessary for an access when expression is
1174 -- statically Null. This is not only an optimization, it is fundamental
1175 -- because otherwise discriminant checks may be generated in init procs
1176 -- for types containing an access to a not-yet-frozen record, causing a
1177 -- deadly forward reference.
1179 -- Also, if the expression is of an access type whose designated type is
1180 -- incomplete, then the access value must be null and we suppress the
1183 if Known_Null (N) then
1186 elsif Is_Access_Type (S_Typ) then
1187 S_Typ := Designated_Type (S_Typ);
1189 if Ekind (S_Typ) = E_Incomplete_Type then
1194 -- If an assignment target is present, then we need to generate the
1195 -- actual subtype if the target is a parameter or aliased object with
1196 -- an unconstrained nominal subtype.
1198 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1199 -- subtype to the parameter and dereference cases, since other aliased
1200 -- objects are unconstrained (unless the nominal subtype is explicitly
1204 and then (Present (Param_Entity (Lhs))
1205 or else (Ada_Version < Ada_05
1206 and then not Is_Constrained (T_Typ)
1207 and then Is_Aliased_View (Lhs)
1208 and then not Is_Aliased_Unconstrained_Component)
1209 or else (Ada_Version >= Ada_05
1210 and then not Is_Constrained (T_Typ)
1211 and then Denotes_Explicit_Dereference (Lhs)
1212 and then Nkind (Original_Node (Lhs)) /=
1215 T_Typ := Get_Actual_Subtype (Lhs);
1218 -- Nothing to do if the type is unconstrained (this is the case where
1219 -- the actual subtype in the RM sense of N is unconstrained and no check
1222 if not Is_Constrained (T_Typ) then
1225 -- Ada 2005: nothing to do if the type is one for which there is a
1226 -- partial view that is constrained.
1228 elsif Ada_Version >= Ada_05
1229 and then Has_Constrained_Partial_View (Base_Type (T_Typ))
1234 -- Nothing to do if the type is an Unchecked_Union
1236 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1240 -- Suppress checks if the subtypes are the same. the check must be
1241 -- preserved in an assignment to a formal, because the constraint is
1242 -- given by the actual.
1244 if Nkind (Original_Node (N)) /= N_Allocator
1246 or else not Is_Entity_Name (Lhs)
1247 or else No (Param_Entity (Lhs)))
1250 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1251 and then not Is_Aliased_View (Lhs)
1256 -- We can also eliminate checks on allocators with a subtype mark that
1257 -- coincides with the context type. The context type may be a subtype
1258 -- without a constraint (common case, a generic actual).
1260 elsif Nkind (Original_Node (N)) = N_Allocator
1261 and then Is_Entity_Name (Expression (Original_Node (N)))
1264 Alloc_Typ : constant Entity_Id :=
1265 Entity (Expression (Original_Node (N)));
1268 if Alloc_Typ = T_Typ
1269 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1270 and then Is_Entity_Name (
1271 Subtype_Indication (Parent (T_Typ)))
1272 and then Alloc_Typ = Base_Type (T_Typ))
1280 -- See if we have a case where the types are both constrained, and all
1281 -- the constraints are constants. In this case, we can do the check
1282 -- successfully at compile time.
1284 -- We skip this check for the case where the node is a rewritten`
1285 -- allocator, because it already carries the context subtype, and
1286 -- extracting the discriminants from the aggregate is messy.
1288 if Is_Constrained (S_Typ)
1289 and then Nkind (Original_Node (N)) /= N_Allocator
1299 -- S_Typ may not have discriminants in the case where it is a
1300 -- private type completed by a default discriminated type. In that
1301 -- case, we need to get the constraints from the underlying_type.
1302 -- If the underlying type is unconstrained (i.e. has no default
1303 -- discriminants) no check is needed.
1305 if Has_Discriminants (S_Typ) then
1306 Discr := First_Discriminant (S_Typ);
1307 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1310 Discr := First_Discriminant (Underlying_Type (S_Typ));
1313 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1319 -- A further optimization: if T_Typ is derived from S_Typ
1320 -- without imposing a constraint, no check is needed.
1322 if Nkind (Original_Node (Parent (T_Typ))) =
1323 N_Full_Type_Declaration
1326 Type_Def : constant Node_Id :=
1328 (Original_Node (Parent (T_Typ)));
1330 if Nkind (Type_Def) = N_Derived_Type_Definition
1331 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1332 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1340 DconT := First_Elmt (Discriminant_Constraint (T_Typ));
1342 while Present (Discr) loop
1343 ItemS := Node (DconS);
1344 ItemT := Node (DconT);
1346 -- For a discriminated component type constrained by the
1347 -- current instance of an enclosing type, there is no
1348 -- applicable discriminant check.
1350 if Nkind (ItemT) = N_Attribute_Reference
1351 and then Is_Access_Type (Etype (ItemT))
1352 and then Is_Entity_Name (Prefix (ItemT))
1353 and then Is_Type (Entity (Prefix (ItemT)))
1358 -- If the expressions for the discriminants are identical
1359 -- and it is side-effect free (for now just an entity),
1360 -- this may be a shared constraint, e.g. from a subtype
1361 -- without a constraint introduced as a generic actual.
1362 -- Examine other discriminants if any.
1365 and then Is_Entity_Name (ItemS)
1369 elsif not Is_OK_Static_Expression (ItemS)
1370 or else not Is_OK_Static_Expression (ItemT)
1374 elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
1375 if Do_Access then -- needs run-time check.
1378 Apply_Compile_Time_Constraint_Error
1379 (N, "incorrect value for discriminant&?",
1380 CE_Discriminant_Check_Failed, Ent => Discr);
1387 Next_Discriminant (Discr);
1396 -- Here we need a discriminant check. First build the expression
1397 -- for the comparisons of the discriminants:
1399 -- (n.disc1 /= typ.disc1) or else
1400 -- (n.disc2 /= typ.disc2) or else
1402 -- (n.discn /= typ.discn)
1404 Cond := Build_Discriminant_Checks (N, T_Typ);
1406 -- If Lhs is set and is a parameter, then the condition is
1407 -- guarded by: lhs'constrained and then (condition built above)
1409 if Present (Param_Entity (Lhs)) then
1413 Make_Attribute_Reference (Loc,
1414 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1415 Attribute_Name => Name_Constrained),
1416 Right_Opnd => Cond);
1420 Cond := Guard_Access (Cond, Loc, N);
1424 Make_Raise_Constraint_Error (Loc,
1426 Reason => CE_Discriminant_Check_Failed));
1427 end Apply_Discriminant_Check;
1429 ------------------------
1430 -- Apply_Divide_Check --
1431 ------------------------
1433 procedure Apply_Divide_Check (N : Node_Id) is
1434 Loc : constant Source_Ptr := Sloc (N);
1435 Typ : constant Entity_Id := Etype (N);
1436 Left : constant Node_Id := Left_Opnd (N);
1437 Right : constant Node_Id := Right_Opnd (N);
1447 pragma Warnings (Off, Lhi);
1448 -- Don't actually use this value
1452 and then not Backend_Divide_Checks_On_Target
1453 and then Check_Needed (Right, Division_Check)
1455 Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True);
1457 -- See if division by zero possible, and if so generate test. This
1458 -- part of the test is not controlled by the -gnato switch.
1460 if Do_Division_Check (N) then
1461 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1463 Make_Raise_Constraint_Error (Loc,
1466 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1467 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1468 Reason => CE_Divide_By_Zero));
1472 -- Test for extremely annoying case of xxx'First divided by -1
1474 if Do_Overflow_Check (N) then
1475 if Nkind (N) = N_Op_Divide
1476 and then Is_Signed_Integer_Type (Typ)
1478 Determine_Range (Left, LOK, Llo, Lhi, Assume_Valid => True);
1479 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1481 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1483 ((not LOK) or else (Llo = LLB))
1486 Make_Raise_Constraint_Error (Loc,
1492 Duplicate_Subexpr_Move_Checks (Left),
1493 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1497 Duplicate_Subexpr (Right),
1499 Make_Integer_Literal (Loc, -1))),
1500 Reason => CE_Overflow_Check_Failed));
1505 end Apply_Divide_Check;
1507 ----------------------------------
1508 -- Apply_Float_Conversion_Check --
1509 ----------------------------------
1511 -- Let F and I be the source and target types of the conversion. The RM
1512 -- specifies that a floating-point value X is rounded to the nearest
1513 -- integer, with halfway cases being rounded away from zero. The rounded
1514 -- value of X is checked against I'Range.
1516 -- The catch in the above paragraph is that there is no good way to know
1517 -- whether the round-to-integer operation resulted in overflow. A remedy is
1518 -- to perform a range check in the floating-point domain instead, however:
1520 -- (1) The bounds may not be known at compile time
1521 -- (2) The check must take into account rounding or truncation.
1522 -- (3) The range of type I may not be exactly representable in F.
1523 -- (4) For the rounding case, The end-points I'First - 0.5 and
1524 -- I'Last + 0.5 may or may not be in range, depending on the
1525 -- sign of I'First and I'Last.
1526 -- (5) X may be a NaN, which will fail any comparison
1528 -- The following steps correctly convert X with rounding:
1530 -- (1) If either I'First or I'Last is not known at compile time, use
1531 -- I'Base instead of I in the next three steps and perform a
1532 -- regular range check against I'Range after conversion.
1533 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1534 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1535 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1536 -- In other words, take one of the closest floating-point numbers
1537 -- (which is an integer value) to I'First, and see if it is in
1539 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1540 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1541 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1542 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1543 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1545 -- For the truncating case, replace steps (2) and (3) as follows:
1546 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1547 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1549 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1550 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1553 procedure Apply_Float_Conversion_Check
1555 Target_Typ : Entity_Id)
1557 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1558 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1559 Loc : constant Source_Ptr := Sloc (Ck_Node);
1560 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1561 Target_Base : constant Entity_Id :=
1562 Implementation_Base_Type (Target_Typ);
1564 Par : constant Node_Id := Parent (Ck_Node);
1565 pragma Assert (Nkind (Par) = N_Type_Conversion);
1566 -- Parent of check node, must be a type conversion
1568 Truncate : constant Boolean := Float_Truncate (Par);
1569 Max_Bound : constant Uint :=
1571 (Machine_Radix (Expr_Type),
1572 Machine_Mantissa (Expr_Type) - 1) - 1;
1574 -- Largest bound, so bound plus or minus half is a machine number of F
1576 Ifirst, Ilast : Uint;
1577 -- Bounds of integer type
1580 -- Bounds to check in floating-point domain
1582 Lo_OK, Hi_OK : Boolean;
1583 -- True iff Lo resp. Hi belongs to I'Range
1585 Lo_Chk, Hi_Chk : Node_Id;
1586 -- Expressions that are False iff check fails
1588 Reason : RT_Exception_Code;
1591 if not Compile_Time_Known_Value (LB)
1592 or not Compile_Time_Known_Value (HB)
1595 -- First check that the value falls in the range of the base type,
1596 -- to prevent overflow during conversion and then perform a
1597 -- regular range check against the (dynamic) bounds.
1599 pragma Assert (Target_Base /= Target_Typ);
1601 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Par);
1604 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1605 Set_Etype (Temp, Target_Base);
1607 Insert_Action (Parent (Par),
1608 Make_Object_Declaration (Loc,
1609 Defining_Identifier => Temp,
1610 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1611 Expression => New_Copy_Tree (Par)),
1612 Suppress => All_Checks);
1615 Make_Raise_Constraint_Error (Loc,
1618 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1619 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1620 Reason => CE_Range_Check_Failed));
1621 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
1627 -- Get the (static) bounds of the target type
1629 Ifirst := Expr_Value (LB);
1630 Ilast := Expr_Value (HB);
1632 -- A simple optimization: if the expression is a universal literal,
1633 -- we can do the comparison with the bounds and the conversion to
1634 -- an integer type statically. The range checks are unchanged.
1636 if Nkind (Ck_Node) = N_Real_Literal
1637 and then Etype (Ck_Node) = Universal_Real
1638 and then Is_Integer_Type (Target_Typ)
1639 and then Nkind (Parent (Ck_Node)) = N_Type_Conversion
1642 Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node));
1645 if Int_Val <= Ilast and then Int_Val >= Ifirst then
1647 -- Conversion is safe
1649 Rewrite (Parent (Ck_Node),
1650 Make_Integer_Literal (Loc, UI_To_Int (Int_Val)));
1651 Analyze_And_Resolve (Parent (Ck_Node), Target_Typ);
1657 -- Check against lower bound
1659 if Truncate and then Ifirst > 0 then
1660 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
1664 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
1667 elsif abs (Ifirst) < Max_Bound then
1668 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
1669 Lo_OK := (Ifirst > 0);
1672 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
1673 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
1678 -- Lo_Chk := (X >= Lo)
1680 Lo_Chk := Make_Op_Ge (Loc,
1681 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1682 Right_Opnd => Make_Real_Literal (Loc, Lo));
1685 -- Lo_Chk := (X > Lo)
1687 Lo_Chk := Make_Op_Gt (Loc,
1688 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1689 Right_Opnd => Make_Real_Literal (Loc, Lo));
1692 -- Check against higher bound
1694 if Truncate and then Ilast < 0 then
1695 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
1699 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
1702 elsif abs (Ilast) < Max_Bound then
1703 Hi := UR_From_Uint (Ilast) + Ureal_Half;
1704 Hi_OK := (Ilast < 0);
1706 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
1707 Hi_OK := (Hi <= UR_From_Uint (Ilast));
1712 -- Hi_Chk := (X <= Hi)
1714 Hi_Chk := Make_Op_Le (Loc,
1715 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1716 Right_Opnd => Make_Real_Literal (Loc, Hi));
1719 -- Hi_Chk := (X < Hi)
1721 Hi_Chk := Make_Op_Lt (Loc,
1722 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1723 Right_Opnd => Make_Real_Literal (Loc, Hi));
1726 -- If the bounds of the target type are the same as those of the base
1727 -- type, the check is an overflow check as a range check is not
1728 -- performed in these cases.
1730 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
1731 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
1733 Reason := CE_Overflow_Check_Failed;
1735 Reason := CE_Range_Check_Failed;
1738 -- Raise CE if either conditions does not hold
1740 Insert_Action (Ck_Node,
1741 Make_Raise_Constraint_Error (Loc,
1742 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
1744 end Apply_Float_Conversion_Check;
1746 ------------------------
1747 -- Apply_Length_Check --
1748 ------------------------
1750 procedure Apply_Length_Check
1752 Target_Typ : Entity_Id;
1753 Source_Typ : Entity_Id := Empty)
1756 Apply_Selected_Length_Checks
1757 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1758 end Apply_Length_Check;
1760 -----------------------
1761 -- Apply_Range_Check --
1762 -----------------------
1764 procedure Apply_Range_Check
1766 Target_Typ : Entity_Id;
1767 Source_Typ : Entity_Id := Empty)
1770 Apply_Selected_Range_Checks
1771 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1772 end Apply_Range_Check;
1774 ------------------------------
1775 -- Apply_Scalar_Range_Check --
1776 ------------------------------
1778 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
1779 -- off if it is already set on.
1781 procedure Apply_Scalar_Range_Check
1783 Target_Typ : Entity_Id;
1784 Source_Typ : Entity_Id := Empty;
1785 Fixed_Int : Boolean := False)
1787 Parnt : constant Node_Id := Parent (Expr);
1789 Arr : Node_Id := Empty; -- initialize to prevent warning
1790 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
1793 Is_Subscr_Ref : Boolean;
1794 -- Set true if Expr is a subscript
1796 Is_Unconstrained_Subscr_Ref : Boolean;
1797 -- Set true if Expr is a subscript of an unconstrained array. In this
1798 -- case we do not attempt to do an analysis of the value against the
1799 -- range of the subscript, since we don't know the actual subtype.
1802 -- Set to True if Expr should be regarded as a real value even though
1803 -- the type of Expr might be discrete.
1805 procedure Bad_Value;
1806 -- Procedure called if value is determined to be out of range
1812 procedure Bad_Value is
1814 Apply_Compile_Time_Constraint_Error
1815 (Expr, "value not in range of}?", CE_Range_Check_Failed,
1820 -- Start of processing for Apply_Scalar_Range_Check
1823 -- Return if check obviously not needed
1826 -- Not needed inside generic
1830 -- Not needed if previous error
1832 or else Target_Typ = Any_Type
1833 or else Nkind (Expr) = N_Error
1835 -- Not needed for non-scalar type
1837 or else not Is_Scalar_Type (Target_Typ)
1839 -- Not needed if we know node raises CE already
1841 or else Raises_Constraint_Error (Expr)
1846 -- Now, see if checks are suppressed
1849 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
1851 if Is_Subscr_Ref then
1852 Arr := Prefix (Parnt);
1853 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
1856 if not Do_Range_Check (Expr) then
1858 -- Subscript reference. Check for Index_Checks suppressed
1860 if Is_Subscr_Ref then
1862 -- Check array type and its base type
1864 if Index_Checks_Suppressed (Arr_Typ)
1865 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
1869 -- Check array itself if it is an entity name
1871 elsif Is_Entity_Name (Arr)
1872 and then Index_Checks_Suppressed (Entity (Arr))
1876 -- Check expression itself if it is an entity name
1878 elsif Is_Entity_Name (Expr)
1879 and then Index_Checks_Suppressed (Entity (Expr))
1884 -- All other cases, check for Range_Checks suppressed
1887 -- Check target type and its base type
1889 if Range_Checks_Suppressed (Target_Typ)
1890 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
1894 -- Check expression itself if it is an entity name
1896 elsif Is_Entity_Name (Expr)
1897 and then Range_Checks_Suppressed (Entity (Expr))
1901 -- If Expr is part of an assignment statement, then check left
1902 -- side of assignment if it is an entity name.
1904 elsif Nkind (Parnt) = N_Assignment_Statement
1905 and then Is_Entity_Name (Name (Parnt))
1906 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
1913 -- Do not set range checks if they are killed
1915 if Nkind (Expr) = N_Unchecked_Type_Conversion
1916 and then Kill_Range_Check (Expr)
1921 -- Do not set range checks for any values from System.Scalar_Values
1922 -- since the whole idea of such values is to avoid checking them!
1924 if Is_Entity_Name (Expr)
1925 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
1930 -- Now see if we need a check
1932 if No (Source_Typ) then
1933 S_Typ := Etype (Expr);
1935 S_Typ := Source_Typ;
1938 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
1942 Is_Unconstrained_Subscr_Ref :=
1943 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
1945 -- Always do a range check if the source type includes infinities and
1946 -- the target type does not include infinities. We do not do this if
1947 -- range checks are killed.
1949 if Is_Floating_Point_Type (S_Typ)
1950 and then Has_Infinities (S_Typ)
1951 and then not Has_Infinities (Target_Typ)
1953 Enable_Range_Check (Expr);
1956 -- Return if we know expression is definitely in the range of the target
1957 -- type as determined by Determine_Range. Right now we only do this for
1958 -- discrete types, and not fixed-point or floating-point types.
1960 -- The additional less-precise tests below catch these cases
1962 -- Note: skip this if we are given a source_typ, since the point of
1963 -- supplying a Source_Typ is to stop us looking at the expression.
1964 -- We could sharpen this test to be out parameters only ???
1966 if Is_Discrete_Type (Target_Typ)
1967 and then Is_Discrete_Type (Etype (Expr))
1968 and then not Is_Unconstrained_Subscr_Ref
1969 and then No (Source_Typ)
1972 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
1973 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
1978 if Compile_Time_Known_Value (Tlo)
1979 and then Compile_Time_Known_Value (Thi)
1982 Lov : constant Uint := Expr_Value (Tlo);
1983 Hiv : constant Uint := Expr_Value (Thi);
1986 -- If range is null, we for sure have a constraint error
1987 -- (we don't even need to look at the value involved,
1988 -- since all possible values will raise CE).
1995 -- Otherwise determine range of value
1997 Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True);
2001 -- If definitely in range, all OK
2003 if Lo >= Lov and then Hi <= Hiv then
2006 -- If definitely not in range, warn
2008 elsif Lov > Hi or else Hiv < Lo then
2012 -- Otherwise we don't know
2024 Is_Floating_Point_Type (S_Typ)
2025 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
2027 -- Check if we can determine at compile time whether Expr is in the
2028 -- range of the target type. Note that if S_Typ is within the bounds
2029 -- of Target_Typ then this must be the case. This check is meaningful
2030 -- only if this is not a conversion between integer and real types.
2032 if not Is_Unconstrained_Subscr_Ref
2034 Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
2036 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
2038 Is_In_Range (Expr, Target_Typ,
2039 Assume_Valid => True,
2040 Fixed_Int => Fixed_Int,
2041 Int_Real => Int_Real))
2045 elsif Is_Out_Of_Range (Expr, Target_Typ,
2046 Assume_Valid => True,
2047 Fixed_Int => Fixed_Int,
2048 Int_Real => Int_Real)
2053 -- In the floating-point case, we only do range checks if the type is
2054 -- constrained. We definitely do NOT want range checks for unconstrained
2055 -- types, since we want to have infinities
2057 elsif Is_Floating_Point_Type (S_Typ) then
2058 if Is_Constrained (S_Typ) then
2059 Enable_Range_Check (Expr);
2062 -- For all other cases we enable a range check unconditionally
2065 Enable_Range_Check (Expr);
2068 end Apply_Scalar_Range_Check;
2070 ----------------------------------
2071 -- Apply_Selected_Length_Checks --
2072 ----------------------------------
2074 procedure Apply_Selected_Length_Checks
2076 Target_Typ : Entity_Id;
2077 Source_Typ : Entity_Id;
2078 Do_Static : Boolean)
2081 R_Result : Check_Result;
2084 Loc : constant Source_Ptr := Sloc (Ck_Node);
2085 Checks_On : constant Boolean :=
2086 (not Index_Checks_Suppressed (Target_Typ))
2088 (not Length_Checks_Suppressed (Target_Typ));
2091 if not Expander_Active then
2096 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2098 for J in 1 .. 2 loop
2099 R_Cno := R_Result (J);
2100 exit when No (R_Cno);
2102 -- A length check may mention an Itype which is attached to a
2103 -- subsequent node. At the top level in a package this can cause
2104 -- an order-of-elaboration problem, so we make sure that the itype
2105 -- is referenced now.
2107 if Ekind (Current_Scope) = E_Package
2108 and then Is_Compilation_Unit (Current_Scope)
2110 Ensure_Defined (Target_Typ, Ck_Node);
2112 if Present (Source_Typ) then
2113 Ensure_Defined (Source_Typ, Ck_Node);
2115 elsif Is_Itype (Etype (Ck_Node)) then
2116 Ensure_Defined (Etype (Ck_Node), Ck_Node);
2120 -- If the item is a conditional raise of constraint error, then have
2121 -- a look at what check is being performed and ???
2123 if Nkind (R_Cno) = N_Raise_Constraint_Error
2124 and then Present (Condition (R_Cno))
2126 Cond := Condition (R_Cno);
2128 -- Case where node does not now have a dynamic check
2130 if not Has_Dynamic_Length_Check (Ck_Node) then
2132 -- If checks are on, just insert the check
2135 Insert_Action (Ck_Node, R_Cno);
2137 if not Do_Static then
2138 Set_Has_Dynamic_Length_Check (Ck_Node);
2141 -- If checks are off, then analyze the length check after
2142 -- temporarily attaching it to the tree in case the relevant
2143 -- condition can be evaluted at compile time. We still want a
2144 -- compile time warning in this case.
2147 Set_Parent (R_Cno, Ck_Node);
2152 -- Output a warning if the condition is known to be True
2154 if Is_Entity_Name (Cond)
2155 and then Entity (Cond) = Standard_True
2157 Apply_Compile_Time_Constraint_Error
2158 (Ck_Node, "wrong length for array of}?",
2159 CE_Length_Check_Failed,
2163 -- If we were only doing a static check, or if checks are not
2164 -- on, then we want to delete the check, since it is not needed.
2165 -- We do this by replacing the if statement by a null statement
2167 elsif Do_Static or else not Checks_On then
2168 Remove_Warning_Messages (R_Cno);
2169 Rewrite (R_Cno, Make_Null_Statement (Loc));
2173 Install_Static_Check (R_Cno, Loc);
2176 end Apply_Selected_Length_Checks;
2178 ---------------------------------
2179 -- Apply_Selected_Range_Checks --
2180 ---------------------------------
2182 procedure Apply_Selected_Range_Checks
2184 Target_Typ : Entity_Id;
2185 Source_Typ : Entity_Id;
2186 Do_Static : Boolean)
2189 R_Result : Check_Result;
2192 Loc : constant Source_Ptr := Sloc (Ck_Node);
2193 Checks_On : constant Boolean :=
2194 (not Index_Checks_Suppressed (Target_Typ))
2196 (not Range_Checks_Suppressed (Target_Typ));
2199 if not Expander_Active or else not Checks_On then
2204 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2206 for J in 1 .. 2 loop
2208 R_Cno := R_Result (J);
2209 exit when No (R_Cno);
2211 -- If the item is a conditional raise of constraint error, then have
2212 -- a look at what check is being performed and ???
2214 if Nkind (R_Cno) = N_Raise_Constraint_Error
2215 and then Present (Condition (R_Cno))
2217 Cond := Condition (R_Cno);
2219 if not Has_Dynamic_Range_Check (Ck_Node) then
2220 Insert_Action (Ck_Node, R_Cno);
2222 if not Do_Static then
2223 Set_Has_Dynamic_Range_Check (Ck_Node);
2227 -- Output a warning if the condition is known to be True
2229 if Is_Entity_Name (Cond)
2230 and then Entity (Cond) = Standard_True
2232 -- Since an N_Range is technically not an expression, we have
2233 -- to set one of the bounds to C_E and then just flag the
2234 -- N_Range. The warning message will point to the lower bound
2235 -- and complain about a range, which seems OK.
2237 if Nkind (Ck_Node) = N_Range then
2238 Apply_Compile_Time_Constraint_Error
2239 (Low_Bound (Ck_Node), "static range out of bounds of}?",
2240 CE_Range_Check_Failed,
2244 Set_Raises_Constraint_Error (Ck_Node);
2247 Apply_Compile_Time_Constraint_Error
2248 (Ck_Node, "static value out of range of}?",
2249 CE_Range_Check_Failed,
2254 -- If we were only doing a static check, or if checks are not
2255 -- on, then we want to delete the check, since it is not needed.
2256 -- We do this by replacing the if statement by a null statement
2258 elsif Do_Static or else not Checks_On then
2259 Remove_Warning_Messages (R_Cno);
2260 Rewrite (R_Cno, Make_Null_Statement (Loc));
2264 Install_Static_Check (R_Cno, Loc);
2267 end Apply_Selected_Range_Checks;
2269 -------------------------------
2270 -- Apply_Static_Length_Check --
2271 -------------------------------
2273 procedure Apply_Static_Length_Check
2275 Target_Typ : Entity_Id;
2276 Source_Typ : Entity_Id := Empty)
2279 Apply_Selected_Length_Checks
2280 (Expr, Target_Typ, Source_Typ, Do_Static => True);
2281 end Apply_Static_Length_Check;
2283 -------------------------------------
2284 -- Apply_Subscript_Validity_Checks --
2285 -------------------------------------
2287 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
2291 pragma Assert (Nkind (Expr) = N_Indexed_Component);
2293 -- Loop through subscripts
2295 Sub := First (Expressions (Expr));
2296 while Present (Sub) loop
2298 -- Check one subscript. Note that we do not worry about enumeration
2299 -- type with holes, since we will convert the value to a Pos value
2300 -- for the subscript, and that convert will do the necessary validity
2303 Ensure_Valid (Sub, Holes_OK => True);
2305 -- Move to next subscript
2309 end Apply_Subscript_Validity_Checks;
2311 ----------------------------------
2312 -- Apply_Type_Conversion_Checks --
2313 ----------------------------------
2315 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
2316 Target_Type : constant Entity_Id := Etype (N);
2317 Target_Base : constant Entity_Id := Base_Type (Target_Type);
2318 Expr : constant Node_Id := Expression (N);
2319 Expr_Type : constant Entity_Id := Etype (Expr);
2322 if Inside_A_Generic then
2325 -- Skip these checks if serious errors detected, there are some nasty
2326 -- situations of incomplete trees that blow things up.
2328 elsif Serious_Errors_Detected > 0 then
2331 -- Scalar type conversions of the form Target_Type (Expr) require a
2332 -- range check if we cannot be sure that Expr is in the base type of
2333 -- Target_Typ and also that Expr is in the range of Target_Typ. These
2334 -- are not quite the same condition from an implementation point of
2335 -- view, but clearly the second includes the first.
2337 elsif Is_Scalar_Type (Target_Type) then
2339 Conv_OK : constant Boolean := Conversion_OK (N);
2340 -- If the Conversion_OK flag on the type conversion is set and no
2341 -- floating point type is involved in the type conversion then
2342 -- fixed point values must be read as integral values.
2344 Float_To_Int : constant Boolean :=
2345 Is_Floating_Point_Type (Expr_Type)
2346 and then Is_Integer_Type (Target_Type);
2349 if not Overflow_Checks_Suppressed (Target_Base)
2351 In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK)
2352 and then not Float_To_Int
2354 Activate_Overflow_Check (N);
2357 if not Range_Checks_Suppressed (Target_Type)
2358 and then not Range_Checks_Suppressed (Expr_Type)
2360 if Float_To_Int then
2361 Apply_Float_Conversion_Check (Expr, Target_Type);
2363 Apply_Scalar_Range_Check
2364 (Expr, Target_Type, Fixed_Int => Conv_OK);
2369 elsif Comes_From_Source (N)
2370 and then not Discriminant_Checks_Suppressed (Target_Type)
2371 and then Is_Record_Type (Target_Type)
2372 and then Is_Derived_Type (Target_Type)
2373 and then not Is_Tagged_Type (Target_Type)
2374 and then not Is_Constrained (Target_Type)
2375 and then Present (Stored_Constraint (Target_Type))
2377 -- An unconstrained derived type may have inherited discriminant
2378 -- Build an actual discriminant constraint list using the stored
2379 -- constraint, to verify that the expression of the parent type
2380 -- satisfies the constraints imposed by the (unconstrained!)
2381 -- derived type. This applies to value conversions, not to view
2382 -- conversions of tagged types.
2385 Loc : constant Source_Ptr := Sloc (N);
2387 Constraint : Elmt_Id;
2388 Discr_Value : Node_Id;
2391 New_Constraints : constant Elist_Id := New_Elmt_List;
2392 Old_Constraints : constant Elist_Id :=
2393 Discriminant_Constraint (Expr_Type);
2396 Constraint := First_Elmt (Stored_Constraint (Target_Type));
2397 while Present (Constraint) loop
2398 Discr_Value := Node (Constraint);
2400 if Is_Entity_Name (Discr_Value)
2401 and then Ekind (Entity (Discr_Value)) = E_Discriminant
2403 Discr := Corresponding_Discriminant (Entity (Discr_Value));
2406 and then Scope (Discr) = Base_Type (Expr_Type)
2408 -- Parent is constrained by new discriminant. Obtain
2409 -- Value of original discriminant in expression. If the
2410 -- new discriminant has been used to constrain more than
2411 -- one of the stored discriminants, this will provide the
2412 -- required consistency check.
2415 Make_Selected_Component (Loc,
2417 Duplicate_Subexpr_No_Checks
2418 (Expr, Name_Req => True),
2420 Make_Identifier (Loc, Chars (Discr))),
2424 -- Discriminant of more remote ancestor ???
2429 -- Derived type definition has an explicit value for this
2430 -- stored discriminant.
2434 (Duplicate_Subexpr_No_Checks (Discr_Value),
2438 Next_Elmt (Constraint);
2441 -- Use the unconstrained expression type to retrieve the
2442 -- discriminants of the parent, and apply momentarily the
2443 -- discriminant constraint synthesized above.
2445 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
2446 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
2447 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
2450 Make_Raise_Constraint_Error (Loc,
2452 Reason => CE_Discriminant_Check_Failed));
2455 -- For arrays, conversions are applied during expansion, to take into
2456 -- accounts changes of representation. The checks become range checks on
2457 -- the base type or length checks on the subtype, depending on whether
2458 -- the target type is unconstrained or constrained.
2463 end Apply_Type_Conversion_Checks;
2465 ----------------------------------------------
2466 -- Apply_Universal_Integer_Attribute_Checks --
2467 ----------------------------------------------
2469 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
2470 Loc : constant Source_Ptr := Sloc (N);
2471 Typ : constant Entity_Id := Etype (N);
2474 if Inside_A_Generic then
2477 -- Nothing to do if checks are suppressed
2479 elsif Range_Checks_Suppressed (Typ)
2480 and then Overflow_Checks_Suppressed (Typ)
2484 -- Nothing to do if the attribute does not come from source. The
2485 -- internal attributes we generate of this type do not need checks,
2486 -- and furthermore the attempt to check them causes some circular
2487 -- elaboration orders when dealing with packed types.
2489 elsif not Comes_From_Source (N) then
2492 -- If the prefix is a selected component that depends on a discriminant
2493 -- the check may improperly expose a discriminant instead of using
2494 -- the bounds of the object itself. Set the type of the attribute to
2495 -- the base type of the context, so that a check will be imposed when
2496 -- needed (e.g. if the node appears as an index).
2498 elsif Nkind (Prefix (N)) = N_Selected_Component
2499 and then Ekind (Typ) = E_Signed_Integer_Subtype
2500 and then Depends_On_Discriminant (Scalar_Range (Typ))
2502 Set_Etype (N, Base_Type (Typ));
2504 -- Otherwise, replace the attribute node with a type conversion node
2505 -- whose expression is the attribute, retyped to universal integer, and
2506 -- whose subtype mark is the target type. The call to analyze this
2507 -- conversion will set range and overflow checks as required for proper
2508 -- detection of an out of range value.
2511 Set_Etype (N, Universal_Integer);
2512 Set_Analyzed (N, True);
2515 Make_Type_Conversion (Loc,
2516 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
2517 Expression => Relocate_Node (N)));
2519 Analyze_And_Resolve (N, Typ);
2522 end Apply_Universal_Integer_Attribute_Checks;
2524 -------------------------------
2525 -- Build_Discriminant_Checks --
2526 -------------------------------
2528 function Build_Discriminant_Checks
2530 T_Typ : Entity_Id) return Node_Id
2532 Loc : constant Source_Ptr := Sloc (N);
2535 Disc_Ent : Entity_Id;
2539 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
2541 ----------------------------------
2542 -- Aggregate_Discriminant_Value --
2543 ----------------------------------
2545 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
2549 -- The aggregate has been normalized with named associations. We use
2550 -- the Chars field to locate the discriminant to take into account
2551 -- discriminants in derived types, which carry the same name as those
2554 Assoc := First (Component_Associations (N));
2555 while Present (Assoc) loop
2556 if Chars (First (Choices (Assoc))) = Chars (Disc) then
2557 return Expression (Assoc);
2563 -- Discriminant must have been found in the loop above
2565 raise Program_Error;
2566 end Aggregate_Discriminant_Val;
2568 -- Start of processing for Build_Discriminant_Checks
2571 -- Loop through discriminants evolving the condition
2574 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
2576 -- For a fully private type, use the discriminants of the parent type
2578 if Is_Private_Type (T_Typ)
2579 and then No (Full_View (T_Typ))
2581 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
2583 Disc_Ent := First_Discriminant (T_Typ);
2586 while Present (Disc) loop
2587 Dval := Node (Disc);
2589 if Nkind (Dval) = N_Identifier
2590 and then Ekind (Entity (Dval)) = E_Discriminant
2592 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
2594 Dval := Duplicate_Subexpr_No_Checks (Dval);
2597 -- If we have an Unchecked_Union node, we can infer the discriminants
2600 if Is_Unchecked_Union (Base_Type (T_Typ)) then
2602 Get_Discriminant_Value (
2603 First_Discriminant (T_Typ),
2605 Stored_Constraint (T_Typ)));
2607 elsif Nkind (N) = N_Aggregate then
2609 Duplicate_Subexpr_No_Checks
2610 (Aggregate_Discriminant_Val (Disc_Ent));
2614 Make_Selected_Component (Loc,
2616 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
2618 Make_Identifier (Loc, Chars (Disc_Ent)));
2620 Set_Is_In_Discriminant_Check (Dref);
2623 Evolve_Or_Else (Cond,
2626 Right_Opnd => Dval));
2629 Next_Discriminant (Disc_Ent);
2633 end Build_Discriminant_Checks;
2639 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
2647 -- Always check if not simple entity
2649 if Nkind (Nod) not in N_Has_Entity
2650 or else not Comes_From_Source (Nod)
2655 -- Look up tree for short circuit
2662 -- Done if out of subexpression (note that we allow generated stuff
2663 -- such as itype declarations in this context, to keep the loop going
2664 -- since we may well have generated such stuff in complex situations.
2665 -- Also done if no parent (probably an error condition, but no point
2666 -- in behaving nasty if we find it!)
2669 or else (K not in N_Subexpr and then Comes_From_Source (P))
2673 -- Or/Or Else case, where test is part of the right operand, or is
2674 -- part of one of the actions associated with the right operand, and
2675 -- the left operand is an equality test.
2677 elsif K = N_Op_Or then
2678 exit when N = Right_Opnd (P)
2679 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2681 elsif K = N_Or_Else then
2682 exit when (N = Right_Opnd (P)
2685 and then List_Containing (N) = Actions (P)))
2686 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2688 -- Similar test for the And/And then case, where the left operand
2689 -- is an inequality test.
2691 elsif K = N_Op_And then
2692 exit when N = Right_Opnd (P)
2693 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2695 elsif K = N_And_Then then
2696 exit when (N = Right_Opnd (P)
2699 and then List_Containing (N) = Actions (P)))
2700 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2706 -- If we fall through the loop, then we have a conditional with an
2707 -- appropriate test as its left operand. So test further.
2710 R := Right_Opnd (L);
2713 -- Left operand of test must match original variable
2715 if Nkind (L) not in N_Has_Entity
2716 or else Entity (L) /= Entity (Nod)
2721 -- Right operand of test must be key value (zero or null)
2724 when Access_Check =>
2725 if not Known_Null (R) then
2729 when Division_Check =>
2730 if not Compile_Time_Known_Value (R)
2731 or else Expr_Value (R) /= Uint_0
2737 raise Program_Error;
2740 -- Here we have the optimizable case, warn if not short-circuited
2742 if K = N_Op_And or else K = N_Op_Or then
2744 when Access_Check =>
2746 ("Constraint_Error may be raised (access check)?",
2748 when Division_Check =>
2750 ("Constraint_Error may be raised (zero divide)?",
2754 raise Program_Error;
2757 if K = N_Op_And then
2758 Error_Msg_N -- CODEFIX
2759 ("use `AND THEN` instead of AND?", P);
2761 Error_Msg_N -- CODEFIX
2762 ("use `OR ELSE` instead of OR?", P);
2765 -- If not short-circuited, we need the ckeck
2769 -- If short-circuited, we can omit the check
2776 -----------------------------------
2777 -- Check_Valid_Lvalue_Subscripts --
2778 -----------------------------------
2780 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
2782 -- Skip this if range checks are suppressed
2784 if Range_Checks_Suppressed (Etype (Expr)) then
2787 -- Only do this check for expressions that come from source. We assume
2788 -- that expander generated assignments explicitly include any necessary
2789 -- checks. Note that this is not just an optimization, it avoids
2790 -- infinite recursions!
2792 elsif not Comes_From_Source (Expr) then
2795 -- For a selected component, check the prefix
2797 elsif Nkind (Expr) = N_Selected_Component then
2798 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2801 -- Case of indexed component
2803 elsif Nkind (Expr) = N_Indexed_Component then
2804 Apply_Subscript_Validity_Checks (Expr);
2806 -- Prefix may itself be or contain an indexed component, and these
2807 -- subscripts need checking as well.
2809 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2811 end Check_Valid_Lvalue_Subscripts;
2813 ----------------------------------
2814 -- Null_Exclusion_Static_Checks --
2815 ----------------------------------
2817 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
2818 Error_Node : Node_Id;
2820 Has_Null : constant Boolean := Has_Null_Exclusion (N);
2821 K : constant Node_Kind := Nkind (N);
2826 (K = N_Component_Declaration
2827 or else K = N_Discriminant_Specification
2828 or else K = N_Function_Specification
2829 or else K = N_Object_Declaration
2830 or else K = N_Parameter_Specification);
2832 if K = N_Function_Specification then
2833 Typ := Etype (Defining_Entity (N));
2835 Typ := Etype (Defining_Identifier (N));
2839 when N_Component_Declaration =>
2840 if Present (Access_Definition (Component_Definition (N))) then
2841 Error_Node := Component_Definition (N);
2843 Error_Node := Subtype_Indication (Component_Definition (N));
2846 when N_Discriminant_Specification =>
2847 Error_Node := Discriminant_Type (N);
2849 when N_Function_Specification =>
2850 Error_Node := Result_Definition (N);
2852 when N_Object_Declaration =>
2853 Error_Node := Object_Definition (N);
2855 when N_Parameter_Specification =>
2856 Error_Node := Parameter_Type (N);
2859 raise Program_Error;
2864 -- Enforce legality rule 3.10 (13): A null exclusion can only be
2865 -- applied to an access [sub]type.
2867 if not Is_Access_Type (Typ) then
2869 ("`NOT NULL` allowed only for an access type", Error_Node);
2871 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
2872 -- be applied to a [sub]type that does not exclude null already.
2874 elsif Can_Never_Be_Null (Typ)
2875 and then Comes_From_Source (Typ)
2878 ("`NOT NULL` not allowed (& already excludes null)",
2883 -- Check that null-excluding objects are always initialized, except for
2884 -- deferred constants, for which the expression will appear in the full
2887 if K = N_Object_Declaration
2888 and then No (Expression (N))
2889 and then not Constant_Present (N)
2890 and then not No_Initialization (N)
2892 -- Add an expression that assigns null. This node is needed by
2893 -- Apply_Compile_Time_Constraint_Error, which will replace this with
2894 -- a Constraint_Error node.
2896 Set_Expression (N, Make_Null (Sloc (N)));
2897 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
2899 Apply_Compile_Time_Constraint_Error
2900 (N => Expression (N),
2901 Msg => "(Ada 2005) null-excluding objects must be initialized?",
2902 Reason => CE_Null_Not_Allowed);
2905 -- Check that a null-excluding component, formal or object is not being
2906 -- assigned a null value. Otherwise generate a warning message and
2907 -- replace Expression (N) by an N_Constraint_Error node.
2909 if K /= N_Function_Specification then
2910 Expr := Expression (N);
2912 if Present (Expr) and then Known_Null (Expr) then
2914 when N_Component_Declaration |
2915 N_Discriminant_Specification =>
2916 Apply_Compile_Time_Constraint_Error
2918 Msg => "(Ada 2005) null not allowed " &
2919 "in null-excluding components?",
2920 Reason => CE_Null_Not_Allowed);
2922 when N_Object_Declaration =>
2923 Apply_Compile_Time_Constraint_Error
2925 Msg => "(Ada 2005) null not allowed " &
2926 "in null-excluding objects?",
2927 Reason => CE_Null_Not_Allowed);
2929 when N_Parameter_Specification =>
2930 Apply_Compile_Time_Constraint_Error
2932 Msg => "(Ada 2005) null not allowed " &
2933 "in null-excluding formals?",
2934 Reason => CE_Null_Not_Allowed);
2941 end Null_Exclusion_Static_Checks;
2943 ----------------------------------
2944 -- Conditional_Statements_Begin --
2945 ----------------------------------
2947 procedure Conditional_Statements_Begin is
2949 Saved_Checks_TOS := Saved_Checks_TOS + 1;
2951 -- If stack overflows, kill all checks, that way we know to simply reset
2952 -- the number of saved checks to zero on return. This should never occur
2955 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2958 -- In the normal case, we just make a new stack entry saving the current
2959 -- number of saved checks for a later restore.
2962 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
2964 if Debug_Flag_CC then
2965 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
2969 end Conditional_Statements_Begin;
2971 --------------------------------
2972 -- Conditional_Statements_End --
2973 --------------------------------
2975 procedure Conditional_Statements_End is
2977 pragma Assert (Saved_Checks_TOS > 0);
2979 -- If the saved checks stack overflowed, then we killed all checks, so
2980 -- setting the number of saved checks back to zero is correct. This
2981 -- should never occur in practice.
2983 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2984 Num_Saved_Checks := 0;
2986 -- In the normal case, restore the number of saved checks from the top
2990 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
2991 if Debug_Flag_CC then
2992 w ("Conditional_Statements_End: Num_Saved_Checks = ",
2997 Saved_Checks_TOS := Saved_Checks_TOS - 1;
2998 end Conditional_Statements_End;
3000 ---------------------
3001 -- Determine_Range --
3002 ---------------------
3004 Cache_Size : constant := 2 ** 10;
3005 type Cache_Index is range 0 .. Cache_Size - 1;
3006 -- Determine size of below cache (power of 2 is more efficient!)
3008 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
3009 Determine_Range_Cache_V : array (Cache_Index) of Boolean;
3010 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
3011 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
3012 -- The above arrays are used to implement a small direct cache for
3013 -- Determine_Range calls. Because of the way Determine_Range recursively
3014 -- traces subexpressions, and because overflow checking calls the routine
3015 -- on the way up the tree, a quadratic behavior can otherwise be
3016 -- encountered in large expressions. The cache entry for node N is stored
3017 -- in the (N mod Cache_Size) entry, and can be validated by checking the
3018 -- actual node value stored there. The Range_Cache_V array records the
3019 -- setting of Assume_Valid for the cache entry.
3021 procedure Determine_Range
3026 Assume_Valid : Boolean := False)
3028 Typ : Entity_Id := Etype (N);
3029 -- Type to use, may get reset to base type for possibly invalid entity
3033 -- Lo and Hi bounds of left operand
3037 -- Lo and Hi bounds of right (or only) operand
3040 -- Temp variable used to hold a bound node
3043 -- High bound of base type of expression
3047 -- Refined values for low and high bounds, after tightening
3050 -- Used in lower level calls to indicate if call succeeded
3052 Cindex : Cache_Index;
3053 -- Used to search cache
3055 function OK_Operands return Boolean;
3056 -- Used for binary operators. Determines the ranges of the left and
3057 -- right operands, and if they are both OK, returns True, and puts
3058 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
3064 function OK_Operands return Boolean is
3067 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
3074 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3078 -- Start of processing for Determine_Range
3081 -- Prevent junk warnings by initializing range variables
3088 -- If type is not defined, we can't determine its range
3092 -- We don't deal with anything except discrete types
3094 or else not Is_Discrete_Type (Typ)
3096 -- Ignore type for which an error has been posted, since range in
3097 -- this case may well be a bogosity deriving from the error. Also
3098 -- ignore if error posted on the reference node.
3100 or else Error_Posted (N) or else Error_Posted (Typ)
3106 -- For all other cases, we can determine the range
3110 -- If value is compile time known, then the possible range is the one
3111 -- value that we know this expression definitely has!
3113 if Compile_Time_Known_Value (N) then
3114 Lo := Expr_Value (N);
3119 -- Return if already in the cache
3121 Cindex := Cache_Index (N mod Cache_Size);
3123 if Determine_Range_Cache_N (Cindex) = N
3125 Determine_Range_Cache_V (Cindex) = Assume_Valid
3127 Lo := Determine_Range_Cache_Lo (Cindex);
3128 Hi := Determine_Range_Cache_Hi (Cindex);
3132 -- Otherwise, start by finding the bounds of the type of the expression,
3133 -- the value cannot be outside this range (if it is, then we have an
3134 -- overflow situation, which is a separate check, we are talking here
3135 -- only about the expression value).
3137 -- First a check, never try to find the bounds of a generic type, since
3138 -- these bounds are always junk values, and it is only valid to look at
3139 -- the bounds in an instance.
3141 if Is_Generic_Type (Typ) then
3146 -- First step, change to use base type unless we know the value is valid
3148 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
3149 or else Assume_No_Invalid_Values
3150 or else Assume_Valid
3154 Typ := Underlying_Type (Base_Type (Typ));
3157 -- We use the actual bound unless it is dynamic, in which case use the
3158 -- corresponding base type bound if possible. If we can't get a bound
3159 -- then we figure we can't determine the range (a peculiar case, that
3160 -- perhaps cannot happen, but there is no point in bombing in this
3161 -- optimization circuit.
3163 -- First the low bound
3165 Bound := Type_Low_Bound (Typ);
3167 if Compile_Time_Known_Value (Bound) then
3168 Lo := Expr_Value (Bound);
3170 elsif Compile_Time_Known_Value (Type_Low_Bound (Base_Type (Typ))) then
3171 Lo := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
3178 -- Now the high bound
3180 Bound := Type_High_Bound (Typ);
3182 -- We need the high bound of the base type later on, and this should
3183 -- always be compile time known. Again, it is not clear that this
3184 -- can ever be false, but no point in bombing.
3186 if Compile_Time_Known_Value (Type_High_Bound (Base_Type (Typ))) then
3187 Hbound := Expr_Value (Type_High_Bound (Base_Type (Typ)));
3195 -- If we have a static subtype, then that may have a tighter bound so
3196 -- use the upper bound of the subtype instead in this case.
3198 if Compile_Time_Known_Value (Bound) then
3199 Hi := Expr_Value (Bound);
3202 -- We may be able to refine this value in certain situations. If any
3203 -- refinement is possible, then Lor and Hir are set to possibly tighter
3204 -- bounds, and OK1 is set to True.
3208 -- For unary plus, result is limited by range of operand
3212 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
3214 -- For unary minus, determine range of operand, and negate it
3218 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3225 -- For binary addition, get range of each operand and do the
3226 -- addition to get the result range.
3230 Lor := Lo_Left + Lo_Right;
3231 Hir := Hi_Left + Hi_Right;
3234 -- Division is tricky. The only case we consider is where the right
3235 -- operand is a positive constant, and in this case we simply divide
3236 -- the bounds of the left operand
3240 if Lo_Right = Hi_Right
3241 and then Lo_Right > 0
3243 Lor := Lo_Left / Lo_Right;
3244 Hir := Hi_Left / Lo_Right;
3251 -- For binary subtraction, get range of each operand and do the worst
3252 -- case subtraction to get the result range.
3254 when N_Op_Subtract =>
3256 Lor := Lo_Left - Hi_Right;
3257 Hir := Hi_Left - Lo_Right;
3260 -- For MOD, if right operand is a positive constant, then result must
3261 -- be in the allowable range of mod results.
3265 if Lo_Right = Hi_Right
3266 and then Lo_Right /= 0
3268 if Lo_Right > 0 then
3270 Hir := Lo_Right - 1;
3272 else -- Lo_Right < 0
3273 Lor := Lo_Right + 1;
3282 -- For REM, if right operand is a positive constant, then result must
3283 -- be in the allowable range of mod results.
3287 if Lo_Right = Hi_Right
3288 and then Lo_Right /= 0
3291 Dval : constant Uint := (abs Lo_Right) - 1;
3294 -- The sign of the result depends on the sign of the
3295 -- dividend (but not on the sign of the divisor, hence
3296 -- the abs operation above).
3316 -- Attribute reference cases
3318 when N_Attribute_Reference =>
3319 case Attribute_Name (N) is
3321 -- For Pos/Val attributes, we can refine the range using the
3322 -- possible range of values of the attribute expression.
3324 when Name_Pos | Name_Val =>
3326 (First (Expressions (N)), OK1, Lor, Hir, Assume_Valid);
3328 -- For Length attribute, use the bounds of the corresponding
3329 -- index type to refine the range.
3333 Atyp : Entity_Id := Etype (Prefix (N));
3341 if Is_Access_Type (Atyp) then
3342 Atyp := Designated_Type (Atyp);
3345 -- For string literal, we know exact value
3347 if Ekind (Atyp) = E_String_Literal_Subtype then
3349 Lo := String_Literal_Length (Atyp);
3350 Hi := String_Literal_Length (Atyp);
3354 -- Otherwise check for expression given
3356 if No (Expressions (N)) then
3360 UI_To_Int (Expr_Value (First (Expressions (N))));
3363 Indx := First_Index (Atyp);
3364 for J in 2 .. Inum loop
3365 Indx := Next_Index (Indx);
3368 -- If the index type is a formal type or derived from
3369 -- one, the bounds are not static.
3371 if Is_Generic_Type (Root_Type (Etype (Indx))) then
3377 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU,
3382 (Type_High_Bound (Etype (Indx)), OK1, UL, UU,
3387 -- The maximum value for Length is the biggest
3388 -- possible gap between the values of the bounds.
3389 -- But of course, this value cannot be negative.
3391 Hir := UI_Max (Uint_0, UU - LL + 1);
3393 -- For constrained arrays, the minimum value for
3394 -- Length is taken from the actual value of the
3395 -- bounds, since the index will be exactly of this
3398 if Is_Constrained (Atyp) then
3399 Lor := UI_Max (Uint_0, UL - LU + 1);
3401 -- For an unconstrained array, the minimum value
3402 -- for length is always zero.
3411 -- No special handling for other attributes
3412 -- Probably more opportunities exist here???
3419 -- For type conversion from one discrete type to another, we can
3420 -- refine the range using the converted value.
3422 when N_Type_Conversion =>
3423 Determine_Range (Expression (N), OK1, Lor, Hir, Assume_Valid);
3425 -- Nothing special to do for all other expression kinds
3433 -- At this stage, if OK1 is true, then we know that the actual result of
3434 -- the computed expression is in the range Lor .. Hir. We can use this
3435 -- to restrict the possible range of results.
3439 -- If the refined value of the low bound is greater than the type
3440 -- high bound, then reset it to the more restrictive value. However,
3441 -- we do NOT do this for the case of a modular type where the
3442 -- possible upper bound on the value is above the base type high
3443 -- bound, because that means the result could wrap.
3446 and then not (Is_Modular_Integer_Type (Typ) and then Hir > Hbound)
3451 -- Similarly, if the refined value of the high bound is less than the
3452 -- value so far, then reset it to the more restrictive value. Again,
3453 -- we do not do this if the refined low bound is negative for a
3454 -- modular type, since this would wrap.
3457 and then not (Is_Modular_Integer_Type (Typ) and then Lor < Uint_0)
3463 -- Set cache entry for future call and we are all done
3465 Determine_Range_Cache_N (Cindex) := N;
3466 Determine_Range_Cache_V (Cindex) := Assume_Valid;
3467 Determine_Range_Cache_Lo (Cindex) := Lo;
3468 Determine_Range_Cache_Hi (Cindex) := Hi;
3471 -- If any exception occurs, it means that we have some bug in the compiler,
3472 -- possibly triggered by a previous error, or by some unforeseen peculiar
3473 -- occurrence. However, this is only an optimization attempt, so there is
3474 -- really no point in crashing the compiler. Instead we just decide, too
3475 -- bad, we can't figure out a range in this case after all.
3480 -- Debug flag K disables this behavior (useful for debugging)
3482 if Debug_Flag_K then
3490 end Determine_Range;
3492 ------------------------------------
3493 -- Discriminant_Checks_Suppressed --
3494 ------------------------------------
3496 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
3499 if Is_Unchecked_Union (E) then
3501 elsif Checks_May_Be_Suppressed (E) then
3502 return Is_Check_Suppressed (E, Discriminant_Check);
3506 return Scope_Suppress (Discriminant_Check);
3507 end Discriminant_Checks_Suppressed;
3509 --------------------------------
3510 -- Division_Checks_Suppressed --
3511 --------------------------------
3513 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
3515 if Present (E) and then Checks_May_Be_Suppressed (E) then
3516 return Is_Check_Suppressed (E, Division_Check);
3518 return Scope_Suppress (Division_Check);
3520 end Division_Checks_Suppressed;
3522 -----------------------------------
3523 -- Elaboration_Checks_Suppressed --
3524 -----------------------------------
3526 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
3528 -- The complication in this routine is that if we are in the dynamic
3529 -- model of elaboration, we also check All_Checks, since All_Checks
3530 -- does not set Elaboration_Check explicitly.
3533 if Kill_Elaboration_Checks (E) then
3536 elsif Checks_May_Be_Suppressed (E) then
3537 if Is_Check_Suppressed (E, Elaboration_Check) then
3539 elsif Dynamic_Elaboration_Checks then
3540 return Is_Check_Suppressed (E, All_Checks);
3547 if Scope_Suppress (Elaboration_Check) then
3549 elsif Dynamic_Elaboration_Checks then
3550 return Scope_Suppress (All_Checks);
3554 end Elaboration_Checks_Suppressed;
3556 ---------------------------
3557 -- Enable_Overflow_Check --
3558 ---------------------------
3560 procedure Enable_Overflow_Check (N : Node_Id) is
3561 Typ : constant Entity_Id := Base_Type (Etype (N));
3570 if Debug_Flag_CC then
3571 w ("Enable_Overflow_Check for node ", Int (N));
3572 Write_Str (" Source location = ");
3577 -- No check if overflow checks suppressed for type of node
3579 if Present (Etype (N))
3580 and then Overflow_Checks_Suppressed (Etype (N))
3584 -- Nothing to do for unsigned integer types, which do not overflow
3586 elsif Is_Modular_Integer_Type (Typ) then
3589 -- Nothing to do if the range of the result is known OK. We skip this
3590 -- for conversions, since the caller already did the check, and in any
3591 -- case the condition for deleting the check for a type conversion is
3594 elsif Nkind (N) /= N_Type_Conversion then
3595 Determine_Range (N, OK, Lo, Hi, Assume_Valid => True);
3597 -- Note in the test below that we assume that the range is not OK
3598 -- if a bound of the range is equal to that of the type. That's not
3599 -- quite accurate but we do this for the following reasons:
3601 -- a) The way that Determine_Range works, it will typically report
3602 -- the bounds of the value as being equal to the bounds of the
3603 -- type, because it either can't tell anything more precise, or
3604 -- does not think it is worth the effort to be more precise.
3606 -- b) It is very unusual to have a situation in which this would
3607 -- generate an unnecessary overflow check (an example would be
3608 -- a subtype with a range 0 .. Integer'Last - 1 to which the
3609 -- literal value one is added).
3611 -- c) The alternative is a lot of special casing in this routine
3612 -- which would partially duplicate Determine_Range processing.
3615 and then Lo > Expr_Value (Type_Low_Bound (Typ))
3616 and then Hi < Expr_Value (Type_High_Bound (Typ))
3618 if Debug_Flag_CC then
3619 w ("No overflow check required");
3626 -- If not in optimizing mode, set flag and we are done. We are also done
3627 -- (and just set the flag) if the type is not a discrete type, since it
3628 -- is not worth the effort to eliminate checks for other than discrete
3629 -- types. In addition, we take this same path if we have stored the
3630 -- maximum number of checks possible already (a very unlikely situation,
3631 -- but we do not want to blow up!)
3633 if Optimization_Level = 0
3634 or else not Is_Discrete_Type (Etype (N))
3635 or else Num_Saved_Checks = Saved_Checks'Last
3637 Activate_Overflow_Check (N);
3639 if Debug_Flag_CC then
3640 w ("Optimization off");
3646 -- Otherwise evaluate and check the expression
3651 Target_Type => Empty,
3657 if Debug_Flag_CC then
3658 w ("Called Find_Check");
3662 w (" Check_Num = ", Chk);
3663 w (" Ent = ", Int (Ent));
3664 Write_Str (" Ofs = ");
3669 -- If check is not of form to optimize, then set flag and we are done
3672 Activate_Overflow_Check (N);
3676 -- If check is already performed, then return without setting flag
3679 if Debug_Flag_CC then
3680 w ("Check suppressed!");
3686 -- Here we will make a new entry for the new check
3688 Activate_Overflow_Check (N);
3689 Num_Saved_Checks := Num_Saved_Checks + 1;
3690 Saved_Checks (Num_Saved_Checks) :=
3695 Target_Type => Empty);
3697 if Debug_Flag_CC then
3698 w ("Make new entry, check number = ", Num_Saved_Checks);
3699 w (" Entity = ", Int (Ent));
3700 Write_Str (" Offset = ");
3702 w (" Check_Type = O");
3703 w (" Target_Type = Empty");
3706 -- If we get an exception, then something went wrong, probably because of
3707 -- an error in the structure of the tree due to an incorrect program. Or it
3708 -- may be a bug in the optimization circuit. In either case the safest
3709 -- thing is simply to set the check flag unconditionally.
3713 Activate_Overflow_Check (N);
3715 if Debug_Flag_CC then
3716 w (" exception occurred, overflow flag set");
3720 end Enable_Overflow_Check;
3722 ------------------------
3723 -- Enable_Range_Check --
3724 ------------------------
3726 procedure Enable_Range_Check (N : Node_Id) is
3735 -- Return if unchecked type conversion with range check killed. In this
3736 -- case we never set the flag (that's what Kill_Range_Check is about!)
3738 if Nkind (N) = N_Unchecked_Type_Conversion
3739 and then Kill_Range_Check (N)
3744 -- Check for various cases where we should suppress the range check
3746 -- No check if range checks suppressed for type of node
3748 if Present (Etype (N))
3749 and then Range_Checks_Suppressed (Etype (N))
3753 -- No check if node is an entity name, and range checks are suppressed
3754 -- for this entity, or for the type of this entity.
3756 elsif Is_Entity_Name (N)
3757 and then (Range_Checks_Suppressed (Entity (N))
3758 or else Range_Checks_Suppressed (Etype (Entity (N))))
3762 -- No checks if index of array, and index checks are suppressed for
3763 -- the array object or the type of the array.
3765 elsif Nkind (Parent (N)) = N_Indexed_Component then
3767 Pref : constant Node_Id := Prefix (Parent (N));
3769 if Is_Entity_Name (Pref)
3770 and then Index_Checks_Suppressed (Entity (Pref))
3773 elsif Index_Checks_Suppressed (Etype (Pref)) then
3779 -- Debug trace output
3781 if Debug_Flag_CC then
3782 w ("Enable_Range_Check for node ", Int (N));
3783 Write_Str (" Source location = ");
3788 -- If not in optimizing mode, set flag and we are done. We are also done
3789 -- (and just set the flag) if the type is not a discrete type, since it
3790 -- is not worth the effort to eliminate checks for other than discrete
3791 -- types. In addition, we take this same path if we have stored the
3792 -- maximum number of checks possible already (a very unlikely situation,
3793 -- but we do not want to blow up!)
3795 if Optimization_Level = 0
3796 or else No (Etype (N))
3797 or else not Is_Discrete_Type (Etype (N))
3798 or else Num_Saved_Checks = Saved_Checks'Last
3800 Activate_Range_Check (N);
3802 if Debug_Flag_CC then
3803 w ("Optimization off");
3809 -- Otherwise find out the target type
3813 -- For assignment, use left side subtype
3815 if Nkind (P) = N_Assignment_Statement
3816 and then Expression (P) = N
3818 Ttyp := Etype (Name (P));
3820 -- For indexed component, use subscript subtype
3822 elsif Nkind (P) = N_Indexed_Component then
3829 Atyp := Etype (Prefix (P));
3831 if Is_Access_Type (Atyp) then
3832 Atyp := Designated_Type (Atyp);
3834 -- If the prefix is an access to an unconstrained array,
3835 -- perform check unconditionally: it depends on the bounds of
3836 -- an object and we cannot currently recognize whether the test
3837 -- may be redundant.
3839 if not Is_Constrained (Atyp) then
3840 Activate_Range_Check (N);
3844 -- Ditto if the prefix is an explicit dereference whose designated
3845 -- type is unconstrained.
3847 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
3848 and then not Is_Constrained (Atyp)
3850 Activate_Range_Check (N);
3854 Indx := First_Index (Atyp);
3855 Subs := First (Expressions (P));
3858 Ttyp := Etype (Indx);
3867 -- For now, ignore all other cases, they are not so interesting
3870 if Debug_Flag_CC then
3871 w (" target type not found, flag set");
3874 Activate_Range_Check (N);
3878 -- Evaluate and check the expression
3883 Target_Type => Ttyp,
3889 if Debug_Flag_CC then
3890 w ("Called Find_Check");
3891 w ("Target_Typ = ", Int (Ttyp));
3895 w (" Check_Num = ", Chk);
3896 w (" Ent = ", Int (Ent));
3897 Write_Str (" Ofs = ");
3902 -- If check is not of form to optimize, then set flag and we are done
3905 if Debug_Flag_CC then
3906 w (" expression not of optimizable type, flag set");
3909 Activate_Range_Check (N);
3913 -- If check is already performed, then return without setting flag
3916 if Debug_Flag_CC then
3917 w ("Check suppressed!");
3923 -- Here we will make a new entry for the new check
3925 Activate_Range_Check (N);
3926 Num_Saved_Checks := Num_Saved_Checks + 1;
3927 Saved_Checks (Num_Saved_Checks) :=
3932 Target_Type => Ttyp);
3934 if Debug_Flag_CC then
3935 w ("Make new entry, check number = ", Num_Saved_Checks);
3936 w (" Entity = ", Int (Ent));
3937 Write_Str (" Offset = ");
3939 w (" Check_Type = R");
3940 w (" Target_Type = ", Int (Ttyp));
3941 pg (Union_Id (Ttyp));
3944 -- If we get an exception, then something went wrong, probably because of
3945 -- an error in the structure of the tree due to an incorrect program. Or
3946 -- it may be a bug in the optimization circuit. In either case the safest
3947 -- thing is simply to set the check flag unconditionally.
3951 Activate_Range_Check (N);
3953 if Debug_Flag_CC then
3954 w (" exception occurred, range flag set");
3958 end Enable_Range_Check;
3964 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
3965 Typ : constant Entity_Id := Etype (Expr);
3968 -- Ignore call if we are not doing any validity checking
3970 if not Validity_Checks_On then
3973 -- Ignore call if range or validity checks suppressed on entity or type
3975 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
3978 -- No check required if expression is from the expander, we assume the
3979 -- expander will generate whatever checks are needed. Note that this is
3980 -- not just an optimization, it avoids infinite recursions!
3982 -- Unchecked conversions must be checked, unless they are initialized
3983 -- scalar values, as in a component assignment in an init proc.
3985 -- In addition, we force a check if Force_Validity_Checks is set
3987 elsif not Comes_From_Source (Expr)
3988 and then not Force_Validity_Checks
3989 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
3990 or else Kill_Range_Check (Expr))
3994 -- No check required if expression is known to have valid value
3996 elsif Expr_Known_Valid (Expr) then
3999 -- Ignore case of enumeration with holes where the flag is set not to
4000 -- worry about holes, since no special validity check is needed
4002 elsif Is_Enumeration_Type (Typ)
4003 and then Has_Non_Standard_Rep (Typ)
4008 -- No check required on the left-hand side of an assignment
4010 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
4011 and then Expr = Name (Parent (Expr))
4015 -- No check on a univeral real constant. The context will eventually
4016 -- convert it to a machine number for some target type, or report an
4019 elsif Nkind (Expr) = N_Real_Literal
4020 and then Etype (Expr) = Universal_Real
4024 -- If the expression denotes a component of a packed boolean arrray,
4025 -- no possible check applies. We ignore the old ACATS chestnuts that
4026 -- involve Boolean range True..True.
4028 -- Note: validity checks are generated for expressions that yield a
4029 -- scalar type, when it is possible to create a value that is outside of
4030 -- the type. If this is a one-bit boolean no such value exists. This is
4031 -- an optimization, and it also prevents compiler blowing up during the
4032 -- elaboration of improperly expanded packed array references.
4034 elsif Nkind (Expr) = N_Indexed_Component
4035 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
4036 and then Root_Type (Etype (Expr)) = Standard_Boolean
4040 -- An annoying special case. If this is an out parameter of a scalar
4041 -- type, then the value is not going to be accessed, therefore it is
4042 -- inappropriate to do any validity check at the call site.
4045 -- Only need to worry about scalar types
4047 if Is_Scalar_Type (Typ) then
4057 -- Find actual argument (which may be a parameter association)
4058 -- and the parent of the actual argument (the call statement)
4063 if Nkind (P) = N_Parameter_Association then
4068 -- Only need to worry if we are argument of a procedure call
4069 -- since functions don't have out parameters. If this is an
4070 -- indirect or dispatching call, get signature from the
4073 if Nkind (P) = N_Procedure_Call_Statement then
4074 L := Parameter_Associations (P);
4076 if Is_Entity_Name (Name (P)) then
4077 E := Entity (Name (P));
4079 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
4080 E := Etype (Name (P));
4083 -- Only need to worry if there are indeed actuals, and if
4084 -- this could be a procedure call, otherwise we cannot get a
4085 -- match (either we are not an argument, or the mode of the
4086 -- formal is not OUT). This test also filters out the
4089 if Is_Non_Empty_List (L)
4090 and then Is_Subprogram (E)
4092 -- This is the loop through parameters, looking for an
4093 -- OUT parameter for which we are the argument.
4095 F := First_Formal (E);
4097 while Present (F) loop
4098 if Ekind (F) = E_Out_Parameter and then A = N then
4111 -- If we fall through, a validity check is required
4113 Insert_Valid_Check (Expr);
4115 if Is_Entity_Name (Expr)
4116 and then Safe_To_Capture_Value (Expr, Entity (Expr))
4118 Set_Is_Known_Valid (Entity (Expr));
4122 ----------------------
4123 -- Expr_Known_Valid --
4124 ----------------------
4126 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
4127 Typ : constant Entity_Id := Etype (Expr);
4130 -- Non-scalar types are always considered valid, since they never give
4131 -- rise to the issues of erroneous or bounded error behavior that are
4132 -- the concern. In formal reference manual terms the notion of validity
4133 -- only applies to scalar types. Note that even when packed arrays are
4134 -- represented using modular types, they are still arrays semantically,
4135 -- so they are also always valid (in particular, the unused bits can be
4136 -- random rubbish without affecting the validity of the array value).
4138 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
4141 -- If no validity checking, then everything is considered valid
4143 elsif not Validity_Checks_On then
4146 -- Floating-point types are considered valid unless floating-point
4147 -- validity checks have been specifically turned on.
4149 elsif Is_Floating_Point_Type (Typ)
4150 and then not Validity_Check_Floating_Point
4154 -- If the expression is the value of an object that is known to be
4155 -- valid, then clearly the expression value itself is valid.
4157 elsif Is_Entity_Name (Expr)
4158 and then Is_Known_Valid (Entity (Expr))
4162 -- References to discriminants are always considered valid. The value
4163 -- of a discriminant gets checked when the object is built. Within the
4164 -- record, we consider it valid, and it is important to do so, since
4165 -- otherwise we can try to generate bogus validity checks which
4166 -- reference discriminants out of scope. Discriminants of concurrent
4167 -- types are excluded for the same reason.
4169 elsif Is_Entity_Name (Expr)
4170 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
4174 -- If the type is one for which all values are known valid, then we are
4175 -- sure that the value is valid except in the slightly odd case where
4176 -- the expression is a reference to a variable whose size has been
4177 -- explicitly set to a value greater than the object size.
4179 elsif Is_Known_Valid (Typ) then
4180 if Is_Entity_Name (Expr)
4181 and then Ekind (Entity (Expr)) = E_Variable
4182 and then Esize (Entity (Expr)) > Esize (Typ)
4189 -- Integer and character literals always have valid values, where
4190 -- appropriate these will be range checked in any case.
4192 elsif Nkind (Expr) = N_Integer_Literal
4194 Nkind (Expr) = N_Character_Literal
4198 -- If we have a type conversion or a qualification of a known valid
4199 -- value, then the result will always be valid.
4201 elsif Nkind (Expr) = N_Type_Conversion
4203 Nkind (Expr) = N_Qualified_Expression
4205 return Expr_Known_Valid (Expression (Expr));
4207 -- The result of any operator is always considered valid, since we
4208 -- assume the necessary checks are done by the operator. For operators
4209 -- on floating-point operations, we must also check when the operation
4210 -- is the right-hand side of an assignment, or is an actual in a call.
4212 elsif Nkind (Expr) in N_Op then
4213 if Is_Floating_Point_Type (Typ)
4214 and then Validity_Check_Floating_Point
4216 (Nkind (Parent (Expr)) = N_Assignment_Statement
4217 or else Nkind (Parent (Expr)) = N_Function_Call
4218 or else Nkind (Parent (Expr)) = N_Parameter_Association)
4225 -- The result of a membership test is always valid, since it is true or
4226 -- false, there are no other possibilities.
4228 elsif Nkind (Expr) in N_Membership_Test then
4231 -- For all other cases, we do not know the expression is valid
4236 end Expr_Known_Valid;
4242 procedure Find_Check
4244 Check_Type : Character;
4245 Target_Type : Entity_Id;
4246 Entry_OK : out Boolean;
4247 Check_Num : out Nat;
4248 Ent : out Entity_Id;
4251 function Within_Range_Of
4252 (Target_Type : Entity_Id;
4253 Check_Type : Entity_Id) return Boolean;
4254 -- Given a requirement for checking a range against Target_Type, and
4255 -- and a range Check_Type against which a check has already been made,
4256 -- determines if the check against check type is sufficient to ensure
4257 -- that no check against Target_Type is required.
4259 ---------------------
4260 -- Within_Range_Of --
4261 ---------------------
4263 function Within_Range_Of
4264 (Target_Type : Entity_Id;
4265 Check_Type : Entity_Id) return Boolean
4268 if Target_Type = Check_Type then
4273 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
4274 Thi : constant Node_Id := Type_High_Bound (Target_Type);
4275 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
4276 Chi : constant Node_Id := Type_High_Bound (Check_Type);
4280 or else (Compile_Time_Known_Value (Tlo)
4282 Compile_Time_Known_Value (Clo)
4284 Expr_Value (Clo) >= Expr_Value (Tlo)))
4287 or else (Compile_Time_Known_Value (Thi)
4289 Compile_Time_Known_Value (Chi)
4291 Expr_Value (Chi) <= Expr_Value (Clo)))
4299 end Within_Range_Of;
4301 -- Start of processing for Find_Check
4304 -- Establish default, in case no entry is found
4308 -- Case of expression is simple entity reference
4310 if Is_Entity_Name (Expr) then
4311 Ent := Entity (Expr);
4314 -- Case of expression is entity + known constant
4316 elsif Nkind (Expr) = N_Op_Add
4317 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4318 and then Is_Entity_Name (Left_Opnd (Expr))
4320 Ent := Entity (Left_Opnd (Expr));
4321 Ofs := Expr_Value (Right_Opnd (Expr));
4323 -- Case of expression is entity - known constant
4325 elsif Nkind (Expr) = N_Op_Subtract
4326 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4327 and then Is_Entity_Name (Left_Opnd (Expr))
4329 Ent := Entity (Left_Opnd (Expr));
4330 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
4332 -- Any other expression is not of the right form
4341 -- Come here with expression of appropriate form, check if entity is an
4342 -- appropriate one for our purposes.
4344 if (Ekind (Ent) = E_Variable
4345 or else Is_Constant_Object (Ent))
4346 and then not Is_Library_Level_Entity (Ent)
4354 -- See if there is matching check already
4356 for J in reverse 1 .. Num_Saved_Checks loop
4358 SC : Saved_Check renames Saved_Checks (J);
4361 if SC.Killed = False
4362 and then SC.Entity = Ent
4363 and then SC.Offset = Ofs
4364 and then SC.Check_Type = Check_Type
4365 and then Within_Range_Of (Target_Type, SC.Target_Type)
4373 -- If we fall through entry was not found
4378 ---------------------------------
4379 -- Generate_Discriminant_Check --
4380 ---------------------------------
4382 -- Note: the code for this procedure is derived from the
4383 -- Emit_Discriminant_Check Routine in trans.c.
4385 procedure Generate_Discriminant_Check (N : Node_Id) is
4386 Loc : constant Source_Ptr := Sloc (N);
4387 Pref : constant Node_Id := Prefix (N);
4388 Sel : constant Node_Id := Selector_Name (N);
4390 Orig_Comp : constant Entity_Id :=
4391 Original_Record_Component (Entity (Sel));
4392 -- The original component to be checked
4394 Discr_Fct : constant Entity_Id :=
4395 Discriminant_Checking_Func (Orig_Comp);
4396 -- The discriminant checking function
4399 -- One discriminant to be checked in the type
4401 Real_Discr : Entity_Id;
4402 -- Actual discriminant in the call
4404 Pref_Type : Entity_Id;
4405 -- Type of relevant prefix (ignoring private/access stuff)
4408 -- List of arguments for function call
4411 -- Keep track of the formal corresponding to the actual we build for
4412 -- each discriminant, in order to be able to perform the necessary type
4416 -- Selected component reference for checking function argument
4419 Pref_Type := Etype (Pref);
4421 -- Force evaluation of the prefix, so that it does not get evaluated
4422 -- twice (once for the check, once for the actual reference). Such a
4423 -- double evaluation is always a potential source of inefficiency,
4424 -- and is functionally incorrect in the volatile case, or when the
4425 -- prefix may have side-effects. An entity or a component of an
4426 -- entity requires no evaluation.
4428 if Is_Entity_Name (Pref) then
4429 if Treat_As_Volatile (Entity (Pref)) then
4430 Force_Evaluation (Pref, Name_Req => True);
4433 elsif Treat_As_Volatile (Etype (Pref)) then
4434 Force_Evaluation (Pref, Name_Req => True);
4436 elsif Nkind (Pref) = N_Selected_Component
4437 and then Is_Entity_Name (Prefix (Pref))
4442 Force_Evaluation (Pref, Name_Req => True);
4445 -- For a tagged type, use the scope of the original component to
4446 -- obtain the type, because ???
4448 if Is_Tagged_Type (Scope (Orig_Comp)) then
4449 Pref_Type := Scope (Orig_Comp);
4451 -- For an untagged derived type, use the discriminants of the parent
4452 -- which have been renamed in the derivation, possibly by a one-to-many
4453 -- discriminant constraint. For non-tagged type, initially get the Etype
4457 if Is_Derived_Type (Pref_Type)
4458 and then Number_Discriminants (Pref_Type) /=
4459 Number_Discriminants (Etype (Base_Type (Pref_Type)))
4461 Pref_Type := Etype (Base_Type (Pref_Type));
4465 -- We definitely should have a checking function, This routine should
4466 -- not be called if no discriminant checking function is present.
4468 pragma Assert (Present (Discr_Fct));
4470 -- Create the list of the actual parameters for the call. This list
4471 -- is the list of the discriminant fields of the record expression to
4472 -- be discriminant checked.
4475 Formal := First_Formal (Discr_Fct);
4476 Discr := First_Discriminant (Pref_Type);
4477 while Present (Discr) loop
4479 -- If we have a corresponding discriminant field, and a parent
4480 -- subtype is present, then we want to use the corresponding
4481 -- discriminant since this is the one with the useful value.
4483 if Present (Corresponding_Discriminant (Discr))
4484 and then Ekind (Pref_Type) = E_Record_Type
4485 and then Present (Parent_Subtype (Pref_Type))
4487 Real_Discr := Corresponding_Discriminant (Discr);
4489 Real_Discr := Discr;
4492 -- Construct the reference to the discriminant
4495 Make_Selected_Component (Loc,
4497 Unchecked_Convert_To (Pref_Type,
4498 Duplicate_Subexpr (Pref)),
4499 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
4501 -- Manually analyze and resolve this selected component. We really
4502 -- want it just as it appears above, and do not want the expander
4503 -- playing discriminal games etc with this reference. Then we append
4504 -- the argument to the list we are gathering.
4506 Set_Etype (Scomp, Etype (Real_Discr));
4507 Set_Analyzed (Scomp, True);
4508 Append_To (Args, Convert_To (Etype (Formal), Scomp));
4510 Next_Formal_With_Extras (Formal);
4511 Next_Discriminant (Discr);
4514 -- Now build and insert the call
4517 Make_Raise_Constraint_Error (Loc,
4519 Make_Function_Call (Loc,
4520 Name => New_Occurrence_Of (Discr_Fct, Loc),
4521 Parameter_Associations => Args),
4522 Reason => CE_Discriminant_Check_Failed));
4523 end Generate_Discriminant_Check;
4525 ---------------------------
4526 -- Generate_Index_Checks --
4527 ---------------------------
4529 procedure Generate_Index_Checks (N : Node_Id) is
4530 Loc : constant Source_Ptr := Sloc (N);
4531 A : constant Node_Id := Prefix (N);
4537 -- Ignore call if index checks suppressed for array object or type
4539 if (Is_Entity_Name (A) and then Index_Checks_Suppressed (Entity (A)))
4540 or else Index_Checks_Suppressed (Etype (A))
4545 -- Generate the checks
4547 Sub := First (Expressions (N));
4549 while Present (Sub) loop
4550 if Do_Range_Check (Sub) then
4551 Set_Do_Range_Check (Sub, False);
4553 -- Force evaluation except for the case of a simple name of a
4554 -- non-volatile entity.
4556 if not Is_Entity_Name (Sub)
4557 or else Treat_As_Volatile (Entity (Sub))
4559 Force_Evaluation (Sub);
4562 -- Generate a raise of constraint error with the appropriate
4563 -- reason and a condition of the form:
4565 -- Base_Type(Sub) not in array'range (subscript)
4567 -- Note that the reason we generate the conversion to the base
4568 -- type here is that we definitely want the range check to take
4569 -- place, even if it looks like the subtype is OK. Optimization
4570 -- considerations that allow us to omit the check have already
4571 -- been taken into account in the setting of the Do_Range_Check
4577 Num := New_List (Make_Integer_Literal (Loc, Ind));
4581 Make_Raise_Constraint_Error (Loc,
4585 Convert_To (Base_Type (Etype (Sub)),
4586 Duplicate_Subexpr_Move_Checks (Sub)),
4588 Make_Attribute_Reference (Loc,
4590 Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
4591 Attribute_Name => Name_Range,
4592 Expressions => Num)),
4593 Reason => CE_Index_Check_Failed));
4599 end Generate_Index_Checks;
4601 --------------------------
4602 -- Generate_Range_Check --
4603 --------------------------
4605 procedure Generate_Range_Check
4607 Target_Type : Entity_Id;
4608 Reason : RT_Exception_Code)
4610 Loc : constant Source_Ptr := Sloc (N);
4611 Source_Type : constant Entity_Id := Etype (N);
4612 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
4613 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
4616 -- First special case, if the source type is already within the range
4617 -- of the target type, then no check is needed (probably we should have
4618 -- stopped Do_Range_Check from being set in the first place, but better
4619 -- late than later in preventing junk code!
4621 -- We do NOT apply this if the source node is a literal, since in this
4622 -- case the literal has already been labeled as having the subtype of
4625 if In_Subrange_Of (Source_Type, Target_Type)
4627 (Nkind (N) = N_Integer_Literal
4629 Nkind (N) = N_Real_Literal
4631 Nkind (N) = N_Character_Literal
4634 and then Ekind (Entity (N)) = E_Enumeration_Literal))
4639 -- We need a check, so force evaluation of the node, so that it does
4640 -- not get evaluated twice (once for the check, once for the actual
4641 -- reference). Such a double evaluation is always a potential source
4642 -- of inefficiency, and is functionally incorrect in the volatile case.
4644 if not Is_Entity_Name (N)
4645 or else Treat_As_Volatile (Entity (N))
4647 Force_Evaluation (N);
4650 -- The easiest case is when Source_Base_Type and Target_Base_Type are
4651 -- the same since in this case we can simply do a direct check of the
4652 -- value of N against the bounds of Target_Type.
4654 -- [constraint_error when N not in Target_Type]
4656 -- Note: this is by far the most common case, for example all cases of
4657 -- checks on the RHS of assignments are in this category, but not all
4658 -- cases are like this. Notably conversions can involve two types.
4660 if Source_Base_Type = Target_Base_Type then
4662 Make_Raise_Constraint_Error (Loc,
4665 Left_Opnd => Duplicate_Subexpr (N),
4666 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4669 -- Next test for the case where the target type is within the bounds
4670 -- of the base type of the source type, since in this case we can
4671 -- simply convert these bounds to the base type of T to do the test.
4673 -- [constraint_error when N not in
4674 -- Source_Base_Type (Target_Type'First)
4676 -- Source_Base_Type(Target_Type'Last))]
4678 -- The conversions will always work and need no check
4680 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
4681 -- of converting from an enumeration value to an integer type, such as
4682 -- occurs for the case of generating a range check on Enum'Val(Exp)
4683 -- (which used to be handled by gigi). This is OK, since the conversion
4684 -- itself does not require a check.
4686 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
4688 Make_Raise_Constraint_Error (Loc,
4691 Left_Opnd => Duplicate_Subexpr (N),
4696 Unchecked_Convert_To (Source_Base_Type,
4697 Make_Attribute_Reference (Loc,
4699 New_Occurrence_Of (Target_Type, Loc),
4700 Attribute_Name => Name_First)),
4703 Unchecked_Convert_To (Source_Base_Type,
4704 Make_Attribute_Reference (Loc,
4706 New_Occurrence_Of (Target_Type, Loc),
4707 Attribute_Name => Name_Last)))),
4710 -- Note that at this stage we now that the Target_Base_Type is not in
4711 -- the range of the Source_Base_Type (since even the Target_Type itself
4712 -- is not in this range). It could still be the case that Source_Type is
4713 -- in range of the target base type since we have not checked that case.
4715 -- If that is the case, we can freely convert the source to the target,
4716 -- and then test the target result against the bounds.
4718 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
4720 -- We make a temporary to hold the value of the converted value
4721 -- (converted to the base type), and then we will do the test against
4724 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
4725 -- [constraint_error when Tnn not in Target_Type]
4727 -- Then the conversion itself is replaced by an occurrence of Tnn
4730 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
4733 Insert_Actions (N, New_List (
4734 Make_Object_Declaration (Loc,
4735 Defining_Identifier => Tnn,
4736 Object_Definition =>
4737 New_Occurrence_Of (Target_Base_Type, Loc),
4738 Constant_Present => True,
4740 Make_Type_Conversion (Loc,
4741 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
4742 Expression => Duplicate_Subexpr (N))),
4744 Make_Raise_Constraint_Error (Loc,
4747 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4748 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4750 Reason => Reason)));
4752 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4754 -- Set the type of N, because the declaration for Tnn might not
4755 -- be analyzed yet, as is the case if N appears within a record
4756 -- declaration, as a discriminant constraint or expression.
4758 Set_Etype (N, Target_Base_Type);
4761 -- At this stage, we know that we have two scalar types, which are
4762 -- directly convertible, and where neither scalar type has a base
4763 -- range that is in the range of the other scalar type.
4765 -- The only way this can happen is with a signed and unsigned type.
4766 -- So test for these two cases:
4769 -- Case of the source is unsigned and the target is signed
4771 if Is_Unsigned_Type (Source_Base_Type)
4772 and then not Is_Unsigned_Type (Target_Base_Type)
4774 -- If the source is unsigned and the target is signed, then we
4775 -- know that the source is not shorter than the target (otherwise
4776 -- the source base type would be in the target base type range).
4778 -- In other words, the unsigned type is either the same size as
4779 -- the target, or it is larger. It cannot be smaller.
4782 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
4784 -- We only need to check the low bound if the low bound of the
4785 -- target type is non-negative. If the low bound of the target
4786 -- type is negative, then we know that we will fit fine.
4788 -- If the high bound of the target type is negative, then we
4789 -- know we have a constraint error, since we can't possibly
4790 -- have a negative source.
4792 -- With these two checks out of the way, we can do the check
4793 -- using the source type safely
4795 -- This is definitely the most annoying case!
4797 -- [constraint_error
4798 -- when (Target_Type'First >= 0
4800 -- N < Source_Base_Type (Target_Type'First))
4801 -- or else Target_Type'Last < 0
4802 -- or else N > Source_Base_Type (Target_Type'Last)];
4804 -- We turn off all checks since we know that the conversions
4805 -- will work fine, given the guards for negative values.
4808 Make_Raise_Constraint_Error (Loc,
4814 Left_Opnd => Make_Op_Ge (Loc,
4816 Make_Attribute_Reference (Loc,
4818 New_Occurrence_Of (Target_Type, Loc),
4819 Attribute_Name => Name_First),
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,
4829 New_Occurrence_Of (Target_Type, Loc),
4830 Attribute_Name => Name_First)))),
4835 Make_Attribute_Reference (Loc,
4836 Prefix => New_Occurrence_Of (Target_Type, Loc),
4837 Attribute_Name => Name_Last),
4838 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
4842 Left_Opnd => Duplicate_Subexpr (N),
4844 Convert_To (Source_Base_Type,
4845 Make_Attribute_Reference (Loc,
4846 Prefix => New_Occurrence_Of (Target_Type, Loc),
4847 Attribute_Name => Name_Last)))),
4850 Suppress => All_Checks);
4852 -- Only remaining possibility is that the source is signed and
4853 -- the target is unsigned.
4856 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
4857 and then Is_Unsigned_Type (Target_Base_Type));
4859 -- If the source is signed and the target is unsigned, then we
4860 -- know that the target is not shorter than the source (otherwise
4861 -- the target base type would be in the source base type range).
4863 -- In other words, the unsigned type is either the same size as
4864 -- the target, or it is larger. It cannot be smaller.
4866 -- Clearly we have an error if the source value is negative since
4867 -- no unsigned type can have negative values. If the source type
4868 -- is non-negative, then the check can be done using the target
4871 -- Tnn : constant Target_Base_Type (N) := Target_Type;
4873 -- [constraint_error
4874 -- when N < 0 or else Tnn not in Target_Type];
4876 -- We turn off all checks for the conversion of N to the target
4877 -- base type, since we generate the explicit check to ensure that
4878 -- the value is non-negative
4881 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
4884 Insert_Actions (N, New_List (
4885 Make_Object_Declaration (Loc,
4886 Defining_Identifier => Tnn,
4887 Object_Definition =>
4888 New_Occurrence_Of (Target_Base_Type, Loc),
4889 Constant_Present => True,
4891 Make_Unchecked_Type_Conversion (Loc,
4893 New_Occurrence_Of (Target_Base_Type, Loc),
4894 Expression => Duplicate_Subexpr (N))),
4896 Make_Raise_Constraint_Error (Loc,
4901 Left_Opnd => Duplicate_Subexpr (N),
4902 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4906 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4908 New_Occurrence_Of (Target_Type, Loc))),
4911 Suppress => All_Checks);
4913 -- Set the Etype explicitly, because Insert_Actions may have
4914 -- placed the declaration in the freeze list for an enclosing
4915 -- construct, and thus it is not analyzed yet.
4917 Set_Etype (Tnn, Target_Base_Type);
4918 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4922 end Generate_Range_Check;
4928 function Get_Check_Id (N : Name_Id) return Check_Id is
4930 -- For standard check name, we can do a direct computation
4932 if N in First_Check_Name .. Last_Check_Name then
4933 return Check_Id (N - (First_Check_Name - 1));
4935 -- For non-standard names added by pragma Check_Name, search table
4938 for J in All_Checks + 1 .. Check_Names.Last loop
4939 if Check_Names.Table (J) = N then
4945 -- No matching name found
4950 ---------------------
4951 -- Get_Discriminal --
4952 ---------------------
4954 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
4955 Loc : constant Source_Ptr := Sloc (E);
4960 -- The bound can be a bona fide parameter of a protected operation,
4961 -- rather than a prival encoded as an in-parameter.
4963 if No (Discriminal_Link (Entity (Bound))) then
4967 -- Climb the scope stack looking for an enclosing protected type. If
4968 -- we run out of scopes, return the bound itself.
4971 while Present (Sc) loop
4972 if Sc = Standard_Standard then
4975 elsif Ekind (Sc) = E_Protected_Type then
4982 D := First_Discriminant (Sc);
4983 while Present (D) loop
4984 if Chars (D) = Chars (Bound) then
4985 return New_Occurrence_Of (Discriminal (D), Loc);
4988 Next_Discriminant (D);
4992 end Get_Discriminal;
4994 ----------------------
4995 -- Get_Range_Checks --
4996 ----------------------
4998 function Get_Range_Checks
5000 Target_Typ : Entity_Id;
5001 Source_Typ : Entity_Id := Empty;
5002 Warn_Node : Node_Id := Empty) return Check_Result
5005 return Selected_Range_Checks
5006 (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
5007 end Get_Range_Checks;
5013 function Guard_Access
5016 Ck_Node : Node_Id) return Node_Id
5019 if Nkind (Cond) = N_Or_Else then
5020 Set_Paren_Count (Cond, 1);
5023 if Nkind (Ck_Node) = N_Allocator then
5030 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
5031 Right_Opnd => Make_Null (Loc)),
5032 Right_Opnd => Cond);
5036 -----------------------------
5037 -- Index_Checks_Suppressed --
5038 -----------------------------
5040 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
5042 if Present (E) and then Checks_May_Be_Suppressed (E) then
5043 return Is_Check_Suppressed (E, Index_Check);
5045 return Scope_Suppress (Index_Check);
5047 end Index_Checks_Suppressed;
5053 procedure Initialize is
5055 for J in Determine_Range_Cache_N'Range loop
5056 Determine_Range_Cache_N (J) := Empty;
5061 for J in Int range 1 .. All_Checks loop
5062 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
5066 -------------------------
5067 -- Insert_Range_Checks --
5068 -------------------------
5070 procedure Insert_Range_Checks
5071 (Checks : Check_Result;
5073 Suppress_Typ : Entity_Id;
5074 Static_Sloc : Source_Ptr := No_Location;
5075 Flag_Node : Node_Id := Empty;
5076 Do_Before : Boolean := False)
5078 Internal_Flag_Node : Node_Id := Flag_Node;
5079 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
5081 Check_Node : Node_Id;
5082 Checks_On : constant Boolean :=
5083 (not Index_Checks_Suppressed (Suppress_Typ))
5085 (not Range_Checks_Suppressed (Suppress_Typ));
5088 -- For now we just return if Checks_On is false, however this should be
5089 -- enhanced to check for an always True value in the condition and to
5090 -- generate a compilation warning???
5092 if not Expander_Active or else not Checks_On then
5096 if Static_Sloc = No_Location then
5097 Internal_Static_Sloc := Sloc (Node);
5100 if No (Flag_Node) then
5101 Internal_Flag_Node := Node;
5104 for J in 1 .. 2 loop
5105 exit when No (Checks (J));
5107 if Nkind (Checks (J)) = N_Raise_Constraint_Error
5108 and then Present (Condition (Checks (J)))
5110 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
5111 Check_Node := Checks (J);
5112 Mark_Rewrite_Insertion (Check_Node);
5115 Insert_Before_And_Analyze (Node, Check_Node);
5117 Insert_After_And_Analyze (Node, Check_Node);
5120 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
5125 Make_Raise_Constraint_Error (Internal_Static_Sloc,
5126 Reason => CE_Range_Check_Failed);
5127 Mark_Rewrite_Insertion (Check_Node);
5130 Insert_Before_And_Analyze (Node, Check_Node);
5132 Insert_After_And_Analyze (Node, Check_Node);
5136 end Insert_Range_Checks;
5138 ------------------------
5139 -- Insert_Valid_Check --
5140 ------------------------
5142 procedure Insert_Valid_Check (Expr : Node_Id) is
5143 Loc : constant Source_Ptr := Sloc (Expr);
5147 -- Do not insert if checks off, or if not checking validity or
5148 -- if expression is known to be valid
5150 if not Validity_Checks_On
5151 or else Range_Or_Validity_Checks_Suppressed (Expr)
5152 or else Expr_Known_Valid (Expr)
5157 -- If we have a checked conversion, then validity check applies to
5158 -- the expression inside the conversion, not the result, since if
5159 -- the expression inside is valid, then so is the conversion result.
5162 while Nkind (Exp) = N_Type_Conversion loop
5163 Exp := Expression (Exp);
5166 -- We are about to insert the validity check for Exp. We save and
5167 -- reset the Do_Range_Check flag over this validity check, and then
5168 -- put it back for the final original reference (Exp may be rewritten).
5171 DRC : constant Boolean := Do_Range_Check (Exp);
5174 Set_Do_Range_Check (Exp, False);
5176 -- Force evaluation to avoid multiple reads for atomic/volatile
5178 if Is_Entity_Name (Exp)
5179 and then Is_Volatile (Entity (Exp))
5181 Force_Evaluation (Exp, Name_Req => True);
5184 -- Insert the validity check. Note that we do this with validity
5185 -- checks turned off, to avoid recursion, we do not want validity
5186 -- checks on the validity checking code itself!
5190 Make_Raise_Constraint_Error (Loc,
5194 Make_Attribute_Reference (Loc,
5196 Duplicate_Subexpr_No_Checks (Exp, Name_Req => True),
5197 Attribute_Name => Name_Valid)),
5198 Reason => CE_Invalid_Data),
5199 Suppress => Validity_Check);
5201 -- If the expression is a a reference to an element of a bit-packed
5202 -- array, then it is rewritten as a renaming declaration. If the
5203 -- expression is an actual in a call, it has not been expanded,
5204 -- waiting for the proper point at which to do it. The same happens
5205 -- with renamings, so that we have to force the expansion now. This
5206 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
5209 if Is_Entity_Name (Exp)
5210 and then Nkind (Parent (Entity (Exp))) =
5211 N_Object_Renaming_Declaration
5214 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
5216 if Nkind (Old_Exp) = N_Indexed_Component
5217 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
5219 Expand_Packed_Element_Reference (Old_Exp);
5224 -- Put back the Do_Range_Check flag on the resulting (possibly
5225 -- rewritten) expression.
5227 -- Note: it might be thought that a validity check is not required
5228 -- when a range check is present, but that's not the case, because
5229 -- the back end is allowed to assume for the range check that the
5230 -- operand is within its declared range (an assumption that validity
5231 -- checking is all about NOT assuming!)
5233 -- Note: no need to worry about Possible_Local_Raise here, it will
5234 -- already have been called if original node has Do_Range_Check set.
5236 Set_Do_Range_Check (Exp, DRC);
5238 end Insert_Valid_Check;
5240 ----------------------------------
5241 -- Install_Null_Excluding_Check --
5242 ----------------------------------
5244 procedure Install_Null_Excluding_Check (N : Node_Id) is
5245 Loc : constant Source_Ptr := Sloc (N);
5246 Typ : constant Entity_Id := Etype (N);
5248 function Safe_To_Capture_In_Parameter_Value return Boolean;
5249 -- Determines if it is safe to capture Known_Non_Null status for an
5250 -- the entity referenced by node N. The caller ensures that N is indeed
5251 -- an entity name. It is safe to capture the non-null status for an IN
5252 -- parameter when the reference occurs within a declaration that is sure
5253 -- to be executed as part of the declarative region.
5255 procedure Mark_Non_Null;
5256 -- After installation of check, if the node in question is an entity
5257 -- name, then mark this entity as non-null if possible.
5259 function Safe_To_Capture_In_Parameter_Value return Boolean is
5260 E : constant Entity_Id := Entity (N);
5261 S : constant Entity_Id := Current_Scope;
5265 if Ekind (E) /= E_In_Parameter then
5269 -- Two initial context checks. We must be inside a subprogram body
5270 -- with declarations and reference must not appear in nested scopes.
5272 if (Ekind (S) /= E_Function and then Ekind (S) /= E_Procedure)
5273 or else Scope (E) /= S
5278 S_Par := Parent (Parent (S));
5280 if Nkind (S_Par) /= N_Subprogram_Body
5281 or else No (Declarations (S_Par))
5291 -- Retrieve the declaration node of N (if any). Note that N
5292 -- may be a part of a complex initialization expression.
5296 while Present (P) loop
5298 -- If we have a short circuit form, and we are within the right
5299 -- hand expression, we return false, since the right hand side
5300 -- is not guaranteed to be elaborated.
5302 if Nkind (P) in N_Short_Circuit
5303 and then N = Right_Opnd (P)
5308 -- Similarly, if we are in a conditional expression and not
5309 -- part of the condition, then we return False, since neither
5310 -- the THEN or ELSE expressions will always be elaborated.
5312 if Nkind (P) = N_Conditional_Expression
5313 and then N /= First (Expressions (P))
5318 -- If we are in a case eexpression, and not part of the
5319 -- expression, then we return False, since a particular
5320 -- branch may not always be elaborated
5322 if Nkind (P) = N_Case_Expression
5323 and then N /= Expression (P)
5328 -- While traversing the parent chain, we find that N
5329 -- belongs to a statement, thus it may never appear in
5330 -- a declarative region.
5332 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
5333 or else Nkind (P) = N_Procedure_Call_Statement
5338 -- If we are at a declaration, record it and exit
5340 if Nkind (P) in N_Declaration
5341 and then Nkind (P) not in N_Subprogram_Specification
5354 return List_Containing (N_Decl) = Declarations (S_Par);
5356 end Safe_To_Capture_In_Parameter_Value;
5362 procedure Mark_Non_Null is
5364 -- Only case of interest is if node N is an entity name
5366 if Is_Entity_Name (N) then
5368 -- For sure, we want to clear an indication that this is known to
5369 -- be null, since if we get past this check, it definitely is not!
5371 Set_Is_Known_Null (Entity (N), False);
5373 -- We can mark the entity as known to be non-null if either it is
5374 -- safe to capture the value, or in the case of an IN parameter,
5375 -- which is a constant, if the check we just installed is in the
5376 -- declarative region of the subprogram body. In this latter case,
5377 -- a check is decisive for the rest of the body if the expression
5378 -- is sure to be elaborated, since we know we have to elaborate
5379 -- all declarations before executing the body.
5381 -- Couldn't this always be part of Safe_To_Capture_Value ???
5383 if Safe_To_Capture_Value (N, Entity (N))
5384 or else Safe_To_Capture_In_Parameter_Value
5386 Set_Is_Known_Non_Null (Entity (N));
5391 -- Start of processing for Install_Null_Excluding_Check
5394 pragma Assert (Is_Access_Type (Typ));
5396 -- No check inside a generic (why not???)
5398 if Inside_A_Generic then
5402 -- No check needed if known to be non-null
5404 if Known_Non_Null (N) then
5408 -- If known to be null, here is where we generate a compile time check
5410 if Known_Null (N) then
5412 -- Avoid generating warning message inside init procs
5414 if not Inside_Init_Proc then
5415 Apply_Compile_Time_Constraint_Error
5417 "null value not allowed here?",
5418 CE_Access_Check_Failed);
5421 Make_Raise_Constraint_Error (Loc,
5422 Reason => CE_Access_Check_Failed));
5429 -- If entity is never assigned, for sure a warning is appropriate
5431 if Is_Entity_Name (N) then
5432 Check_Unset_Reference (N);
5435 -- No check needed if checks are suppressed on the range. Note that we
5436 -- don't set Is_Known_Non_Null in this case (we could legitimately do
5437 -- so, since the program is erroneous, but we don't like to casually
5438 -- propagate such conclusions from erroneosity).
5440 if Access_Checks_Suppressed (Typ) then
5444 -- No check needed for access to concurrent record types generated by
5445 -- the expander. This is not just an optimization (though it does indeed
5446 -- remove junk checks). It also avoids generation of junk warnings.
5448 if Nkind (N) in N_Has_Chars
5449 and then Chars (N) = Name_uObject
5450 and then Is_Concurrent_Record_Type
5451 (Directly_Designated_Type (Etype (N)))
5456 -- Otherwise install access check
5459 Make_Raise_Constraint_Error (Loc,
5462 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
5463 Right_Opnd => Make_Null (Loc)),
5464 Reason => CE_Access_Check_Failed));
5467 end Install_Null_Excluding_Check;
5469 --------------------------
5470 -- Install_Static_Check --
5471 --------------------------
5473 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
5474 Stat : constant Boolean := Is_Static_Expression (R_Cno);
5475 Typ : constant Entity_Id := Etype (R_Cno);
5479 Make_Raise_Constraint_Error (Loc,
5480 Reason => CE_Range_Check_Failed));
5481 Set_Analyzed (R_Cno);
5482 Set_Etype (R_Cno, Typ);
5483 Set_Raises_Constraint_Error (R_Cno);
5484 Set_Is_Static_Expression (R_Cno, Stat);
5486 -- Now deal with possible local raise handling
5488 Possible_Local_Raise (R_Cno, Standard_Constraint_Error);
5489 end Install_Static_Check;
5491 ---------------------
5492 -- Kill_All_Checks --
5493 ---------------------
5495 procedure Kill_All_Checks is
5497 if Debug_Flag_CC then
5498 w ("Kill_All_Checks");
5501 -- We reset the number of saved checks to zero, and also modify all
5502 -- stack entries for statement ranges to indicate that the number of
5503 -- checks at each level is now zero.
5505 Num_Saved_Checks := 0;
5507 -- Note: the Int'Min here avoids any possibility of J being out of
5508 -- range when called from e.g. Conditional_Statements_Begin.
5510 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
5511 Saved_Checks_Stack (J) := 0;
5513 end Kill_All_Checks;
5519 procedure Kill_Checks (V : Entity_Id) is
5521 if Debug_Flag_CC then
5522 w ("Kill_Checks for entity", Int (V));
5525 for J in 1 .. Num_Saved_Checks loop
5526 if Saved_Checks (J).Entity = V then
5527 if Debug_Flag_CC then
5528 w (" Checks killed for saved check ", J);
5531 Saved_Checks (J).Killed := True;
5536 ------------------------------
5537 -- Length_Checks_Suppressed --
5538 ------------------------------
5540 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
5542 if Present (E) and then Checks_May_Be_Suppressed (E) then
5543 return Is_Check_Suppressed (E, Length_Check);
5545 return Scope_Suppress (Length_Check);
5547 end Length_Checks_Suppressed;
5549 --------------------------------
5550 -- Overflow_Checks_Suppressed --
5551 --------------------------------
5553 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
5555 if Present (E) and then Checks_May_Be_Suppressed (E) then
5556 return Is_Check_Suppressed (E, Overflow_Check);
5558 return Scope_Suppress (Overflow_Check);
5560 end Overflow_Checks_Suppressed;
5562 -----------------------------
5563 -- Range_Checks_Suppressed --
5564 -----------------------------
5566 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
5570 -- Note: for now we always suppress range checks on Vax float types,
5571 -- since Gigi does not know how to generate these checks.
5573 if Vax_Float (E) then
5575 elsif Kill_Range_Checks (E) then
5577 elsif Checks_May_Be_Suppressed (E) then
5578 return Is_Check_Suppressed (E, Range_Check);
5582 return Scope_Suppress (Range_Check);
5583 end Range_Checks_Suppressed;
5585 -----------------------------------------
5586 -- Range_Or_Validity_Checks_Suppressed --
5587 -----------------------------------------
5589 -- Note: the coding would be simpler here if we simply made appropriate
5590 -- calls to Range/Validity_Checks_Suppressed, but that would result in
5591 -- duplicated checks which we prefer to avoid.
5593 function Range_Or_Validity_Checks_Suppressed
5594 (Expr : Node_Id) return Boolean
5597 -- Immediate return if scope checks suppressed for either check
5599 if Scope_Suppress (Range_Check) or Scope_Suppress (Validity_Check) then
5603 -- If no expression, that's odd, decide that checks are suppressed,
5604 -- since we don't want anyone trying to do checks in this case, which
5605 -- is most likely the result of some other error.
5611 -- Expression is present, so perform suppress checks on type
5614 Typ : constant Entity_Id := Etype (Expr);
5616 if Vax_Float (Typ) then
5618 elsif Checks_May_Be_Suppressed (Typ)
5619 and then (Is_Check_Suppressed (Typ, Range_Check)
5621 Is_Check_Suppressed (Typ, Validity_Check))
5627 -- If expression is an entity name, perform checks on this entity
5629 if Is_Entity_Name (Expr) then
5631 Ent : constant Entity_Id := Entity (Expr);
5633 if Checks_May_Be_Suppressed (Ent) then
5634 return Is_Check_Suppressed (Ent, Range_Check)
5635 or else Is_Check_Suppressed (Ent, Validity_Check);
5640 -- If we fall through, no checks suppressed
5643 end Range_Or_Validity_Checks_Suppressed;
5649 procedure Remove_Checks (Expr : Node_Id) is
5650 function Process (N : Node_Id) return Traverse_Result;
5651 -- Process a single node during the traversal
5653 procedure Traverse is new Traverse_Proc (Process);
5654 -- The traversal procedure itself
5660 function Process (N : Node_Id) return Traverse_Result is
5662 if Nkind (N) not in N_Subexpr then
5666 Set_Do_Range_Check (N, False);
5670 Traverse (Left_Opnd (N));
5673 when N_Attribute_Reference =>
5674 Set_Do_Overflow_Check (N, False);
5676 when N_Function_Call =>
5677 Set_Do_Tag_Check (N, False);
5680 Set_Do_Overflow_Check (N, False);
5684 Set_Do_Division_Check (N, False);
5687 Set_Do_Length_Check (N, False);
5690 Set_Do_Division_Check (N, False);
5693 Set_Do_Length_Check (N, False);
5696 Set_Do_Division_Check (N, False);
5699 Set_Do_Length_Check (N, False);
5706 Traverse (Left_Opnd (N));
5709 when N_Selected_Component =>
5710 Set_Do_Discriminant_Check (N, False);
5712 when N_Type_Conversion =>
5713 Set_Do_Length_Check (N, False);
5714 Set_Do_Tag_Check (N, False);
5715 Set_Do_Overflow_Check (N, False);
5724 -- Start of processing for Remove_Checks
5730 ----------------------------
5731 -- Selected_Length_Checks --
5732 ----------------------------
5734 function Selected_Length_Checks
5736 Target_Typ : Entity_Id;
5737 Source_Typ : Entity_Id;
5738 Warn_Node : Node_Id) return Check_Result
5740 Loc : constant Source_Ptr := Sloc (Ck_Node);
5743 Expr_Actual : Node_Id;
5745 Cond : Node_Id := Empty;
5746 Do_Access : Boolean := False;
5747 Wnode : Node_Id := Warn_Node;
5748 Ret_Result : Check_Result := (Empty, Empty);
5749 Num_Checks : Natural := 0;
5751 procedure Add_Check (N : Node_Id);
5752 -- Adds the action given to Ret_Result if N is non-Empty
5754 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
5755 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
5756 -- Comments required ???
5758 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
5759 -- True for equal literals and for nodes that denote the same constant
5760 -- entity, even if its value is not a static constant. This includes the
5761 -- case of a discriminal reference within an init proc. Removes some
5762 -- obviously superfluous checks.
5764 function Length_E_Cond
5765 (Exptyp : Entity_Id;
5767 Indx : Nat) return Node_Id;
5768 -- Returns expression to compute:
5769 -- Typ'Length /= Exptyp'Length
5771 function Length_N_Cond
5774 Indx : Nat) return Node_Id;
5775 -- Returns expression to compute:
5776 -- Typ'Length /= Expr'Length
5782 procedure Add_Check (N : Node_Id) is
5786 -- For now, ignore attempt to place more than 2 checks ???
5788 if Num_Checks = 2 then
5792 pragma Assert (Num_Checks <= 1);
5793 Num_Checks := Num_Checks + 1;
5794 Ret_Result (Num_Checks) := N;
5802 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
5803 SE : constant Entity_Id := Scope (E);
5805 E1 : Entity_Id := E;
5808 if Ekind (Scope (E)) = E_Record_Type
5809 and then Has_Discriminants (Scope (E))
5811 N := Build_Discriminal_Subtype_Of_Component (E);
5814 Insert_Action (Ck_Node, N);
5815 E1 := Defining_Identifier (N);
5819 if Ekind (E1) = E_String_Literal_Subtype then
5821 Make_Integer_Literal (Loc,
5822 Intval => String_Literal_Length (E1));
5824 elsif SE /= Standard_Standard
5825 and then Ekind (Scope (SE)) = E_Protected_Type
5826 and then Has_Discriminants (Scope (SE))
5827 and then Has_Completion (Scope (SE))
5828 and then not Inside_Init_Proc
5830 -- If the type whose length is needed is a private component
5831 -- constrained by a discriminant, we must expand the 'Length
5832 -- attribute into an explicit computation, using the discriminal
5833 -- of the current protected operation. This is because the actual
5834 -- type of the prival is constructed after the protected opera-
5835 -- tion has been fully expanded.
5838 Indx_Type : Node_Id;
5841 Do_Expand : Boolean := False;
5844 Indx_Type := First_Index (E);
5846 for J in 1 .. Indx - 1 loop
5847 Next_Index (Indx_Type);
5850 Get_Index_Bounds (Indx_Type, Lo, Hi);
5852 if Nkind (Lo) = N_Identifier
5853 and then Ekind (Entity (Lo)) = E_In_Parameter
5855 Lo := Get_Discriminal (E, Lo);
5859 if Nkind (Hi) = N_Identifier
5860 and then Ekind (Entity (Hi)) = E_In_Parameter
5862 Hi := Get_Discriminal (E, Hi);
5867 if not Is_Entity_Name (Lo) then
5868 Lo := Duplicate_Subexpr_No_Checks (Lo);
5871 if not Is_Entity_Name (Hi) then
5872 Lo := Duplicate_Subexpr_No_Checks (Hi);
5878 Make_Op_Subtract (Loc,
5882 Right_Opnd => Make_Integer_Literal (Loc, 1));
5887 Make_Attribute_Reference (Loc,
5888 Attribute_Name => Name_Length,
5890 New_Occurrence_Of (E1, Loc));
5893 Set_Expressions (N, New_List (
5894 Make_Integer_Literal (Loc, Indx)));
5903 Make_Attribute_Reference (Loc,
5904 Attribute_Name => Name_Length,
5906 New_Occurrence_Of (E1, Loc));
5909 Set_Expressions (N, New_List (
5910 Make_Integer_Literal (Loc, Indx)));
5921 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
5924 Make_Attribute_Reference (Loc,
5925 Attribute_Name => Name_Length,
5927 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
5928 Expressions => New_List (
5929 Make_Integer_Literal (Loc, Indx)));
5936 function Length_E_Cond
5937 (Exptyp : Entity_Id;
5939 Indx : Nat) return Node_Id
5944 Left_Opnd => Get_E_Length (Typ, Indx),
5945 Right_Opnd => Get_E_Length (Exptyp, Indx));
5952 function Length_N_Cond
5955 Indx : Nat) return Node_Id
5960 Left_Opnd => Get_E_Length (Typ, Indx),
5961 Right_Opnd => Get_N_Length (Expr, Indx));
5968 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
5971 (Nkind (L) = N_Integer_Literal
5972 and then Nkind (R) = N_Integer_Literal
5973 and then Intval (L) = Intval (R))
5977 and then Ekind (Entity (L)) = E_Constant
5978 and then ((Is_Entity_Name (R)
5979 and then Entity (L) = Entity (R))
5981 (Nkind (R) = N_Type_Conversion
5982 and then Is_Entity_Name (Expression (R))
5983 and then Entity (L) = Entity (Expression (R)))))
5987 and then Ekind (Entity (R)) = E_Constant
5988 and then Nkind (L) = N_Type_Conversion
5989 and then Is_Entity_Name (Expression (L))
5990 and then Entity (R) = Entity (Expression (L)))
5994 and then Is_Entity_Name (R)
5995 and then Entity (L) = Entity (R)
5996 and then Ekind (Entity (L)) = E_In_Parameter
5997 and then Inside_Init_Proc);
6000 -- Start of processing for Selected_Length_Checks
6003 if not Expander_Active then
6007 if Target_Typ = Any_Type
6008 or else Target_Typ = Any_Composite
6009 or else Raises_Constraint_Error (Ck_Node)
6018 T_Typ := Target_Typ;
6020 if No (Source_Typ) then
6021 S_Typ := Etype (Ck_Node);
6023 S_Typ := Source_Typ;
6026 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6030 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6031 S_Typ := Designated_Type (S_Typ);
6032 T_Typ := Designated_Type (T_Typ);
6035 -- A simple optimization for the null case
6037 if Known_Null (Ck_Node) then
6042 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6043 if Is_Constrained (T_Typ) then
6045 -- The checking code to be generated will freeze the
6046 -- corresponding array type. However, we must freeze the
6047 -- type now, so that the freeze node does not appear within
6048 -- the generated condional expression, but ahead of it.
6050 Freeze_Before (Ck_Node, T_Typ);
6052 Expr_Actual := Get_Referenced_Object (Ck_Node);
6053 Exptyp := Get_Actual_Subtype (Ck_Node);
6055 if Is_Access_Type (Exptyp) then
6056 Exptyp := Designated_Type (Exptyp);
6059 -- String_Literal case. This needs to be handled specially be-
6060 -- cause no index types are available for string literals. The
6061 -- condition is simply:
6063 -- T_Typ'Length = string-literal-length
6065 if Nkind (Expr_Actual) = N_String_Literal
6066 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
6070 Left_Opnd => Get_E_Length (T_Typ, 1),
6072 Make_Integer_Literal (Loc,
6074 String_Literal_Length (Etype (Expr_Actual))));
6076 -- General array case. Here we have a usable actual subtype for
6077 -- the expression, and the condition is built from the two types
6080 -- T_Typ'Length /= Exptyp'Length or else
6081 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
6082 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
6085 elsif Is_Constrained (Exptyp) then
6087 Ndims : constant Nat := Number_Dimensions (T_Typ);
6100 -- At the library level, we need to ensure that the type of
6101 -- the object is elaborated before the check itself is
6102 -- emitted. This is only done if the object is in the
6103 -- current compilation unit, otherwise the type is frozen
6104 -- and elaborated in its unit.
6106 if Is_Itype (Exptyp)
6108 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
6110 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
6111 and then In_Open_Scopes (Scope (Exptyp))
6113 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
6114 Set_Itype (Ref_Node, Exptyp);
6115 Insert_Action (Ck_Node, Ref_Node);
6118 L_Index := First_Index (T_Typ);
6119 R_Index := First_Index (Exptyp);
6121 for Indx in 1 .. Ndims loop
6122 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6124 Nkind (R_Index) = N_Raise_Constraint_Error)
6126 Get_Index_Bounds (L_Index, L_Low, L_High);
6127 Get_Index_Bounds (R_Index, R_Low, R_High);
6129 -- Deal with compile time length check. Note that we
6130 -- skip this in the access case, because the access
6131 -- value may be null, so we cannot know statically.
6134 and then Compile_Time_Known_Value (L_Low)
6135 and then Compile_Time_Known_Value (L_High)
6136 and then Compile_Time_Known_Value (R_Low)
6137 and then Compile_Time_Known_Value (R_High)
6139 if Expr_Value (L_High) >= Expr_Value (L_Low) then
6140 L_Length := Expr_Value (L_High) -
6141 Expr_Value (L_Low) + 1;
6143 L_Length := UI_From_Int (0);
6146 if Expr_Value (R_High) >= Expr_Value (R_Low) then
6147 R_Length := Expr_Value (R_High) -
6148 Expr_Value (R_Low) + 1;
6150 R_Length := UI_From_Int (0);
6153 if L_Length > R_Length then
6155 (Compile_Time_Constraint_Error
6156 (Wnode, "too few elements for}?", T_Typ));
6158 elsif L_Length < R_Length then
6160 (Compile_Time_Constraint_Error
6161 (Wnode, "too many elements for}?", T_Typ));
6164 -- The comparison for an individual index subtype
6165 -- is omitted if the corresponding index subtypes
6166 -- statically match, since the result is known to
6167 -- be true. Note that this test is worth while even
6168 -- though we do static evaluation, because non-static
6169 -- subtypes can statically match.
6172 Subtypes_Statically_Match
6173 (Etype (L_Index), Etype (R_Index))
6176 (Same_Bounds (L_Low, R_Low)
6177 and then Same_Bounds (L_High, R_High))
6180 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
6189 -- Handle cases where we do not get a usable actual subtype that
6190 -- is constrained. This happens for example in the function call
6191 -- and explicit dereference cases. In these cases, we have to get
6192 -- the length or range from the expression itself, making sure we
6193 -- do not evaluate it more than once.
6195 -- Here Ck_Node is the original expression, or more properly the
6196 -- result of applying Duplicate_Expr to the original tree, forcing
6197 -- the result to be a name.
6201 Ndims : constant Nat := Number_Dimensions (T_Typ);
6204 -- Build the condition for the explicit dereference case
6206 for Indx in 1 .. Ndims loop
6208 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
6215 -- Construct the test and insert into the tree
6217 if Present (Cond) then
6219 Cond := Guard_Access (Cond, Loc, Ck_Node);
6223 (Make_Raise_Constraint_Error (Loc,
6225 Reason => CE_Length_Check_Failed));
6229 end Selected_Length_Checks;
6231 ---------------------------
6232 -- Selected_Range_Checks --
6233 ---------------------------
6235 function Selected_Range_Checks
6237 Target_Typ : Entity_Id;
6238 Source_Typ : Entity_Id;
6239 Warn_Node : Node_Id) return Check_Result
6241 Loc : constant Source_Ptr := Sloc (Ck_Node);
6244 Expr_Actual : Node_Id;
6246 Cond : Node_Id := Empty;
6247 Do_Access : Boolean := False;
6248 Wnode : Node_Id := Warn_Node;
6249 Ret_Result : Check_Result := (Empty, Empty);
6250 Num_Checks : Integer := 0;
6252 procedure Add_Check (N : Node_Id);
6253 -- Adds the action given to Ret_Result if N is non-Empty
6255 function Discrete_Range_Cond
6257 Typ : Entity_Id) return Node_Id;
6258 -- Returns expression to compute:
6259 -- Low_Bound (Expr) < Typ'First
6261 -- High_Bound (Expr) > Typ'Last
6263 function Discrete_Expr_Cond
6265 Typ : Entity_Id) return Node_Id;
6266 -- Returns expression to compute:
6271 function Get_E_First_Or_Last
6275 Nam : Name_Id) return Node_Id;
6276 -- Returns an attribute reference
6277 -- E'First or E'Last
6278 -- with a source location of Loc.
6280 -- Nam is Name_First or Name_Last, according to which attribute is
6281 -- desired. If Indx is non-zero, it is passed as a literal in the
6282 -- Expressions of the attribute reference (identifying the desired
6283 -- array dimension).
6285 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
6286 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
6287 -- Returns expression to compute:
6288 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
6290 function Range_E_Cond
6291 (Exptyp : Entity_Id;
6295 -- Returns expression to compute:
6296 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
6298 function Range_Equal_E_Cond
6299 (Exptyp : Entity_Id;
6301 Indx : Nat) return Node_Id;
6302 -- Returns expression to compute:
6303 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
6305 function Range_N_Cond
6308 Indx : Nat) return Node_Id;
6309 -- Return expression to compute:
6310 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
6316 procedure Add_Check (N : Node_Id) is
6320 -- For now, ignore attempt to place more than 2 checks ???
6322 if Num_Checks = 2 then
6326 pragma Assert (Num_Checks <= 1);
6327 Num_Checks := Num_Checks + 1;
6328 Ret_Result (Num_Checks) := N;
6332 -------------------------
6333 -- Discrete_Expr_Cond --
6334 -------------------------
6336 function Discrete_Expr_Cond
6338 Typ : Entity_Id) return Node_Id
6346 Convert_To (Base_Type (Typ),
6347 Duplicate_Subexpr_No_Checks (Expr)),
6349 Convert_To (Base_Type (Typ),
6350 Get_E_First_Or_Last (Loc, Typ, 0, Name_First))),
6355 Convert_To (Base_Type (Typ),
6356 Duplicate_Subexpr_No_Checks (Expr)),
6360 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last))));
6361 end Discrete_Expr_Cond;
6363 -------------------------
6364 -- Discrete_Range_Cond --
6365 -------------------------
6367 function Discrete_Range_Cond
6369 Typ : Entity_Id) return Node_Id
6371 LB : Node_Id := Low_Bound (Expr);
6372 HB : Node_Id := High_Bound (Expr);
6374 Left_Opnd : Node_Id;
6375 Right_Opnd : Node_Id;
6378 if Nkind (LB) = N_Identifier
6379 and then Ekind (Entity (LB)) = E_Discriminant
6381 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6384 if Nkind (HB) = N_Identifier
6385 and then Ekind (Entity (HB)) = E_Discriminant
6387 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6394 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
6399 Get_E_First_Or_Last (Loc, Typ, 0, Name_First)));
6401 if Base_Type (Typ) = Typ then
6404 elsif Compile_Time_Known_Value (High_Bound (Scalar_Range (Typ)))
6406 Compile_Time_Known_Value (High_Bound (Scalar_Range
6409 if Is_Floating_Point_Type (Typ) then
6410 if Expr_Value_R (High_Bound (Scalar_Range (Typ))) =
6411 Expr_Value_R (High_Bound (Scalar_Range (Base_Type (Typ))))
6417 if Expr_Value (High_Bound (Scalar_Range (Typ))) =
6418 Expr_Value (High_Bound (Scalar_Range (Base_Type (Typ))))
6429 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
6434 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last)));
6436 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
6437 end Discrete_Range_Cond;
6439 -------------------------
6440 -- Get_E_First_Or_Last --
6441 -------------------------
6443 function Get_E_First_Or_Last
6447 Nam : Name_Id) return Node_Id
6452 Exprs := New_List (Make_Integer_Literal (Loc, UI_From_Int (Indx)));
6457 return Make_Attribute_Reference (Loc,
6458 Prefix => New_Occurrence_Of (E, Loc),
6459 Attribute_Name => Nam,
6460 Expressions => Exprs);
6461 end Get_E_First_Or_Last;
6467 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
6470 Make_Attribute_Reference (Loc,
6471 Attribute_Name => Name_First,
6473 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6474 Expressions => New_List (
6475 Make_Integer_Literal (Loc, Indx)));
6482 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
6485 Make_Attribute_Reference (Loc,
6486 Attribute_Name => Name_Last,
6488 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6489 Expressions => New_List (
6490 Make_Integer_Literal (Loc, Indx)));
6497 function Range_E_Cond
6498 (Exptyp : Entity_Id;
6500 Indx : Nat) return Node_Id
6508 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
6510 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
6515 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
6517 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
6520 ------------------------
6521 -- Range_Equal_E_Cond --
6522 ------------------------
6524 function Range_Equal_E_Cond
6525 (Exptyp : Entity_Id;
6527 Indx : Nat) return Node_Id
6535 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
6537 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
6542 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
6544 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
6545 end Range_Equal_E_Cond;
6551 function Range_N_Cond
6554 Indx : Nat) return Node_Id
6562 Get_N_First (Expr, Indx),
6564 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
6569 Get_N_Last (Expr, Indx),
6571 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
6574 -- Start of processing for Selected_Range_Checks
6577 if not Expander_Active then
6581 if Target_Typ = Any_Type
6582 or else Target_Typ = Any_Composite
6583 or else Raises_Constraint_Error (Ck_Node)
6592 T_Typ := Target_Typ;
6594 if No (Source_Typ) then
6595 S_Typ := Etype (Ck_Node);
6597 S_Typ := Source_Typ;
6600 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6604 -- The order of evaluating T_Typ before S_Typ seems to be critical
6605 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
6606 -- in, and since Node can be an N_Range node, it might be invalid.
6607 -- Should there be an assert check somewhere for taking the Etype of
6608 -- an N_Range node ???
6610 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6611 S_Typ := Designated_Type (S_Typ);
6612 T_Typ := Designated_Type (T_Typ);
6615 -- A simple optimization for the null case
6617 if Known_Null (Ck_Node) then
6622 -- For an N_Range Node, check for a null range and then if not
6623 -- null generate a range check action.
6625 if Nkind (Ck_Node) = N_Range then
6627 -- There's no point in checking a range against itself
6629 if Ck_Node = Scalar_Range (T_Typ) then
6634 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
6635 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
6636 Known_T_LB : constant Boolean := Compile_Time_Known_Value (T_LB);
6637 Known_T_HB : constant Boolean := Compile_Time_Known_Value (T_HB);
6639 LB : Node_Id := Low_Bound (Ck_Node);
6640 HB : Node_Id := High_Bound (Ck_Node);
6644 Null_Range : Boolean;
6645 Out_Of_Range_L : Boolean;
6646 Out_Of_Range_H : Boolean;
6649 -- Compute what is known at compile time
6651 if Known_T_LB and Known_T_HB then
6652 if Compile_Time_Known_Value (LB) then
6655 -- There's no point in checking that a bound is within its
6656 -- own range so pretend that it is known in this case. First
6657 -- deal with low bound.
6659 elsif Ekind (Etype (LB)) = E_Signed_Integer_Subtype
6660 and then Scalar_Range (Etype (LB)) = Scalar_Range (T_Typ)
6669 -- Likewise for the high bound
6671 if Compile_Time_Known_Value (HB) then
6674 elsif Ekind (Etype (HB)) = E_Signed_Integer_Subtype
6675 and then Scalar_Range (Etype (HB)) = Scalar_Range (T_Typ)
6685 -- Check for case where everything is static and we can do the
6686 -- check at compile time. This is skipped if we have an access
6687 -- type, since the access value may be null.
6689 -- ??? This code can be improved since you only need to know that
6690 -- the two respective bounds (LB & T_LB or HB & T_HB) are known at
6691 -- compile time to emit pertinent messages.
6693 if Known_T_LB and Known_T_HB and Known_LB and Known_HB
6696 -- Floating-point case
6698 if Is_Floating_Point_Type (S_Typ) then
6699 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
6701 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
6703 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
6706 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
6708 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
6710 -- Fixed or discrete type case
6713 Null_Range := Expr_Value (HB) < Expr_Value (LB);
6715 (Expr_Value (LB) < Expr_Value (T_LB))
6717 (Expr_Value (LB) > Expr_Value (T_HB));
6720 (Expr_Value (HB) > Expr_Value (T_HB))
6722 (Expr_Value (HB) < Expr_Value (T_LB));
6725 if not Null_Range then
6726 if Out_Of_Range_L then
6727 if No (Warn_Node) then
6729 (Compile_Time_Constraint_Error
6730 (Low_Bound (Ck_Node),
6731 "static value out of range of}?", T_Typ));
6735 (Compile_Time_Constraint_Error
6737 "static range out of bounds of}?", T_Typ));
6741 if Out_Of_Range_H then
6742 if No (Warn_Node) then
6744 (Compile_Time_Constraint_Error
6745 (High_Bound (Ck_Node),
6746 "static value out of range of}?", T_Typ));
6750 (Compile_Time_Constraint_Error
6752 "static range out of bounds of}?", T_Typ));
6759 LB : Node_Id := Low_Bound (Ck_Node);
6760 HB : Node_Id := High_Bound (Ck_Node);
6763 -- If either bound is a discriminant and we are within the
6764 -- record declaration, it is a use of the discriminant in a
6765 -- constraint of a component, and nothing can be checked
6766 -- here. The check will be emitted within the init proc.
6767 -- Before then, the discriminal has no real meaning.
6768 -- Similarly, if the entity is a discriminal, there is no
6769 -- check to perform yet.
6771 -- The same holds within a discriminated synchronized type,
6772 -- where the discriminant may constrain a component or an
6775 if Nkind (LB) = N_Identifier
6776 and then Denotes_Discriminant (LB, True)
6778 if Current_Scope = Scope (Entity (LB))
6779 or else Is_Concurrent_Type (Current_Scope)
6780 or else Ekind (Entity (LB)) /= E_Discriminant
6785 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6789 if Nkind (HB) = N_Identifier
6790 and then Denotes_Discriminant (HB, True)
6792 if Current_Scope = Scope (Entity (HB))
6793 or else Is_Concurrent_Type (Current_Scope)
6794 or else Ekind (Entity (HB)) /= E_Discriminant
6799 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6803 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
6804 Set_Paren_Count (Cond, 1);
6810 Left_Opnd => Duplicate_Subexpr_No_Checks (HB),
6811 Right_Opnd => Duplicate_Subexpr_No_Checks (LB)),
6812 Right_Opnd => Cond);
6817 elsif Is_Scalar_Type (S_Typ) then
6819 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
6820 -- except the above simply sets a flag in the node and lets
6821 -- gigi generate the check base on the Etype of the expression.
6822 -- Sometimes, however we want to do a dynamic check against an
6823 -- arbitrary target type, so we do that here.
6825 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
6826 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6828 -- For literals, we can tell if the constraint error will be
6829 -- raised at compile time, so we never need a dynamic check, but
6830 -- if the exception will be raised, then post the usual warning,
6831 -- and replace the literal with a raise constraint error
6832 -- expression. As usual, skip this for access types
6834 elsif Compile_Time_Known_Value (Ck_Node)
6835 and then not Do_Access
6838 LB : constant Node_Id := Type_Low_Bound (T_Typ);
6839 UB : constant Node_Id := Type_High_Bound (T_Typ);
6841 Out_Of_Range : Boolean;
6842 Static_Bounds : constant Boolean :=
6843 Compile_Time_Known_Value (LB)
6844 and Compile_Time_Known_Value (UB);
6847 -- Following range tests should use Sem_Eval routine ???
6849 if Static_Bounds then
6850 if Is_Floating_Point_Type (S_Typ) then
6852 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
6854 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
6856 -- Fixed or discrete type
6860 Expr_Value (Ck_Node) < Expr_Value (LB)
6862 Expr_Value (Ck_Node) > Expr_Value (UB);
6865 -- Bounds of the type are static and the literal is out of
6866 -- range so output a warning message.
6868 if Out_Of_Range then
6869 if No (Warn_Node) then
6871 (Compile_Time_Constraint_Error
6873 "static value out of range of}?", T_Typ));
6877 (Compile_Time_Constraint_Error
6879 "static value out of range of}?", T_Typ));
6884 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6888 -- Here for the case of a non-static expression, we need a runtime
6889 -- check unless the source type range is guaranteed to be in the
6890 -- range of the target type.
6893 if not In_Subrange_Of (S_Typ, T_Typ) then
6894 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6899 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6900 if Is_Constrained (T_Typ) then
6902 Expr_Actual := Get_Referenced_Object (Ck_Node);
6903 Exptyp := Get_Actual_Subtype (Expr_Actual);
6905 if Is_Access_Type (Exptyp) then
6906 Exptyp := Designated_Type (Exptyp);
6909 -- String_Literal case. This needs to be handled specially be-
6910 -- cause no index types are available for string literals. The
6911 -- condition is simply:
6913 -- T_Typ'Length = string-literal-length
6915 if Nkind (Expr_Actual) = N_String_Literal then
6918 -- General array case. Here we have a usable actual subtype for
6919 -- the expression, and the condition is built from the two types
6921 -- T_Typ'First < Exptyp'First or else
6922 -- T_Typ'Last > Exptyp'Last or else
6923 -- T_Typ'First(1) < Exptyp'First(1) or else
6924 -- T_Typ'Last(1) > Exptyp'Last(1) or else
6927 elsif Is_Constrained (Exptyp) then
6929 Ndims : constant Nat := Number_Dimensions (T_Typ);
6935 L_Index := First_Index (T_Typ);
6936 R_Index := First_Index (Exptyp);
6938 for Indx in 1 .. Ndims loop
6939 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6941 Nkind (R_Index) = N_Raise_Constraint_Error)
6943 -- Deal with compile time length check. Note that we
6944 -- skip this in the access case, because the access
6945 -- value may be null, so we cannot know statically.
6948 Subtypes_Statically_Match
6949 (Etype (L_Index), Etype (R_Index))
6951 -- If the target type is constrained then we
6952 -- have to check for exact equality of bounds
6953 -- (required for qualified expressions).
6955 if Is_Constrained (T_Typ) then
6958 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
6961 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
6971 -- Handle cases where we do not get a usable actual subtype that
6972 -- is constrained. This happens for example in the function call
6973 -- and explicit dereference cases. In these cases, we have to get
6974 -- the length or range from the expression itself, making sure we
6975 -- do not evaluate it more than once.
6977 -- Here Ck_Node is the original expression, or more properly the
6978 -- result of applying Duplicate_Expr to the original tree,
6979 -- forcing the result to be a name.
6983 Ndims : constant Nat := Number_Dimensions (T_Typ);
6986 -- Build the condition for the explicit dereference case
6988 for Indx in 1 .. Ndims loop
6990 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
6996 -- For a conversion to an unconstrained array type, generate an
6997 -- Action to check that the bounds of the source value are within
6998 -- the constraints imposed by the target type (RM 4.6(38)). No
6999 -- check is needed for a conversion to an access to unconstrained
7000 -- array type, as 4.6(24.15/2) requires the designated subtypes
7001 -- of the two access types to statically match.
7003 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
7004 and then not Do_Access
7007 Opnd_Index : Node_Id;
7008 Targ_Index : Node_Id;
7009 Opnd_Range : Node_Id;
7012 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
7013 Targ_Index := First_Index (T_Typ);
7014 while Present (Opnd_Index) loop
7016 -- If the index is a range, use its bounds. If it is an
7017 -- entity (as will be the case if it is a named subtype
7018 -- or an itype created for a slice) retrieve its range.
7020 if Is_Entity_Name (Opnd_Index)
7021 and then Is_Type (Entity (Opnd_Index))
7023 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
7025 Opnd_Range := Opnd_Index;
7028 if Nkind (Opnd_Range) = N_Range then
7030 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7031 Assume_Valid => True)
7034 (High_Bound (Opnd_Range), Etype (Targ_Index),
7035 Assume_Valid => True)
7039 -- If null range, no check needed
7042 Compile_Time_Known_Value (High_Bound (Opnd_Range))
7044 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
7046 Expr_Value (High_Bound (Opnd_Range)) <
7047 Expr_Value (Low_Bound (Opnd_Range))
7051 elsif Is_Out_Of_Range
7052 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7053 Assume_Valid => True)
7056 (High_Bound (Opnd_Range), Etype (Targ_Index),
7057 Assume_Valid => True)
7060 (Compile_Time_Constraint_Error
7061 (Wnode, "value out of range of}?", T_Typ));
7067 (Opnd_Range, Etype (Targ_Index)));
7071 Next_Index (Opnd_Index);
7072 Next_Index (Targ_Index);
7079 -- Construct the test and insert into the tree
7081 if Present (Cond) then
7083 Cond := Guard_Access (Cond, Loc, Ck_Node);
7087 (Make_Raise_Constraint_Error (Loc,
7089 Reason => CE_Range_Check_Failed));
7093 end Selected_Range_Checks;
7095 -------------------------------
7096 -- Storage_Checks_Suppressed --
7097 -------------------------------
7099 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
7101 if Present (E) and then Checks_May_Be_Suppressed (E) then
7102 return Is_Check_Suppressed (E, Storage_Check);
7104 return Scope_Suppress (Storage_Check);
7106 end Storage_Checks_Suppressed;
7108 ---------------------------
7109 -- Tag_Checks_Suppressed --
7110 ---------------------------
7112 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
7115 if Kill_Tag_Checks (E) then
7117 elsif Checks_May_Be_Suppressed (E) then
7118 return Is_Check_Suppressed (E, Tag_Check);
7122 return Scope_Suppress (Tag_Check);
7123 end Tag_Checks_Suppressed;
7125 --------------------------
7126 -- Validity_Check_Range --
7127 --------------------------
7129 procedure Validity_Check_Range (N : Node_Id) is
7131 if Validity_Checks_On and Validity_Check_Operands then
7132 if Nkind (N) = N_Range then
7133 Ensure_Valid (Low_Bound (N));
7134 Ensure_Valid (High_Bound (N));
7137 end Validity_Check_Range;
7139 --------------------------------
7140 -- Validity_Checks_Suppressed --
7141 --------------------------------
7143 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
7145 if Present (E) and then Checks_May_Be_Suppressed (E) then
7146 return Is_Check_Suppressed (E, Validity_Check);
7148 return Scope_Suppress (Validity_Check);
7150 end Validity_Checks_Suppressed;