1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2011, 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 principally 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 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 Full_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 : Entity_Id := Param_Entity (N);
483 Param_Level : Node_Id;
484 Type_Level : Node_Id;
487 if Ada_Version >= Ada_2012
488 and then not Present (Param_Ent)
489 and then Is_Entity_Name (N)
490 and then Ekind_In (Entity (N), E_Constant, E_Variable)
491 and then Present (Effective_Extra_Accessibility (Entity (N)))
493 Param_Ent := Entity (N);
494 while Present (Renamed_Object (Param_Ent)) loop
496 -- Renamed_Object must return an Entity_Name here
497 -- because of preceding "Present (E_E_A (...))" test.
499 Param_Ent := Entity (Renamed_Object (Param_Ent));
503 if Inside_A_Generic then
506 -- Only apply the run-time check if the access parameter has an
507 -- associated extra access level parameter and when the level of the
508 -- type is less deep than the level of the access parameter, and
509 -- accessibility checks are not suppressed.
511 elsif Present (Param_Ent)
512 and then Present (Extra_Accessibility (Param_Ent))
513 and then UI_Gt (Object_Access_Level (N),
514 Deepest_Type_Access_Level (Typ))
515 and then not Accessibility_Checks_Suppressed (Param_Ent)
516 and then not Accessibility_Checks_Suppressed (Typ)
519 New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc);
522 Make_Integer_Literal (Loc, Deepest_Type_Access_Level (Typ));
524 -- Raise Program_Error if the accessibility level of the access
525 -- parameter is deeper than the level of the target access type.
527 Insert_Action (Insert_Node,
528 Make_Raise_Program_Error (Loc,
531 Left_Opnd => Param_Level,
532 Right_Opnd => Type_Level),
533 Reason => PE_Accessibility_Check_Failed));
535 Analyze_And_Resolve (N);
537 end Apply_Accessibility_Check;
539 --------------------------------
540 -- Apply_Address_Clause_Check --
541 --------------------------------
543 procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is
544 AC : constant Node_Id := Address_Clause (E);
545 Loc : constant Source_Ptr := Sloc (AC);
546 Typ : constant Entity_Id := Etype (E);
547 Aexp : constant Node_Id := Expression (AC);
550 -- Address expression (not necessarily the same as Aexp, for example
551 -- when Aexp is a reference to a constant, in which case Expr gets
552 -- reset to reference the value expression of the constant.
554 procedure Compile_Time_Bad_Alignment;
555 -- Post error warnings when alignment is known to be incompatible. Note
556 -- that we do not go as far as inserting a raise of Program_Error since
557 -- this is an erroneous case, and it may happen that we are lucky and an
558 -- underaligned address turns out to be OK after all.
560 --------------------------------
561 -- Compile_Time_Bad_Alignment --
562 --------------------------------
564 procedure Compile_Time_Bad_Alignment is
566 if Address_Clause_Overlay_Warnings then
568 ("?specified address for& may be inconsistent with alignment ",
571 ("\?program execution may be erroneous (RM 13.3(27))",
573 Set_Address_Warning_Posted (AC);
575 end Compile_Time_Bad_Alignment;
577 -- Start of processing for Apply_Address_Clause_Check
580 -- See if alignment check needed. Note that we never need a check if the
581 -- maximum alignment is one, since the check will always succeed.
583 -- Note: we do not check for checks suppressed here, since that check
584 -- was done in Sem_Ch13 when the address clause was processed. We are
585 -- only called if checks were not suppressed. The reason for this is
586 -- that we have to delay the call to Apply_Alignment_Check till freeze
587 -- time (so that all types etc are elaborated), but we have to check
588 -- the status of check suppressing at the point of the address clause.
591 or else not Check_Address_Alignment (AC)
592 or else Maximum_Alignment = 1
597 -- Obtain expression from address clause
599 Expr := Expression (AC);
601 -- The following loop digs for the real expression to use in the check
604 -- For constant, get constant expression
606 if Is_Entity_Name (Expr)
607 and then Ekind (Entity (Expr)) = E_Constant
609 Expr := Constant_Value (Entity (Expr));
611 -- For unchecked conversion, get result to convert
613 elsif Nkind (Expr) = N_Unchecked_Type_Conversion then
614 Expr := Expression (Expr);
616 -- For (common case) of To_Address call, get argument
618 elsif Nkind (Expr) = N_Function_Call
619 and then Is_Entity_Name (Name (Expr))
620 and then Is_RTE (Entity (Name (Expr)), RE_To_Address)
622 Expr := First (Parameter_Associations (Expr));
624 if Nkind (Expr) = N_Parameter_Association then
625 Expr := Explicit_Actual_Parameter (Expr);
628 -- We finally have the real expression
635 -- See if we know that Expr has a bad alignment at compile time
637 if Compile_Time_Known_Value (Expr)
638 and then (Known_Alignment (E) or else Known_Alignment (Typ))
641 AL : Uint := Alignment (Typ);
644 -- The object alignment might be more restrictive than the
647 if Known_Alignment (E) then
651 if Expr_Value (Expr) mod AL /= 0 then
652 Compile_Time_Bad_Alignment;
658 -- If the expression has the form X'Address, then we can find out if
659 -- the object X has an alignment that is compatible with the object E.
660 -- If it hasn't or we don't know, we defer issuing the warning until
661 -- the end of the compilation to take into account back end annotations.
663 elsif Nkind (Expr) = N_Attribute_Reference
664 and then Attribute_Name (Expr) = Name_Address
665 and then Has_Compatible_Alignment (E, Prefix (Expr)) = Known_Compatible
670 -- Here we do not know if the value is acceptable. Strictly we don't
671 -- have to do anything, since if the alignment is bad, we have an
672 -- erroneous program. However we are allowed to check for erroneous
673 -- conditions and we decide to do this by default if the check is not
676 -- However, don't do the check if elaboration code is unwanted
678 if Restriction_Active (No_Elaboration_Code) then
681 -- Generate a check to raise PE if alignment may be inappropriate
684 -- If the original expression is a non-static constant, use the
685 -- name of the constant itself rather than duplicating its
686 -- defining expression, which was extracted above.
688 -- Note: Expr is empty if the address-clause is applied to in-mode
689 -- actuals (allowed by 13.1(22)).
691 if not Present (Expr)
693 (Is_Entity_Name (Expression (AC))
694 and then Ekind (Entity (Expression (AC))) = E_Constant
695 and then Nkind (Parent (Entity (Expression (AC))))
696 = N_Object_Declaration)
698 Expr := New_Copy_Tree (Expression (AC));
700 Remove_Side_Effects (Expr);
703 Insert_After_And_Analyze (N,
704 Make_Raise_Program_Error (Loc,
711 (RTE (RE_Integer_Address), Expr),
713 Make_Attribute_Reference (Loc,
714 Prefix => New_Occurrence_Of (E, Loc),
715 Attribute_Name => Name_Alignment)),
716 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
717 Reason => PE_Misaligned_Address_Value),
718 Suppress => All_Checks);
723 -- If we have some missing run time component in configurable run time
724 -- mode then just skip the check (it is not required in any case).
726 when RE_Not_Available =>
728 end Apply_Address_Clause_Check;
730 -------------------------------------
731 -- Apply_Arithmetic_Overflow_Check --
732 -------------------------------------
734 -- This routine is called only if the type is an integer type, and a
735 -- software arithmetic overflow check may be needed for op (add, subtract,
736 -- or multiply). This check is performed only if Software_Overflow_Checking
737 -- is enabled and Do_Overflow_Check is set. In this case we expand the
738 -- operation into a more complex sequence of tests that ensures that
739 -- overflow is properly caught.
741 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
742 Loc : constant Source_Ptr := Sloc (N);
743 Typ : constant Entity_Id := Etype (N);
744 Rtyp : constant Entity_Id := Root_Type (Typ);
747 -- An interesting special case. If the arithmetic operation appears as
748 -- the operand of a type conversion:
752 -- and all the following conditions apply:
754 -- arithmetic operation is for a signed integer type
755 -- target type type1 is a static integer subtype
756 -- range of x and y are both included in the range of type1
757 -- range of x op y is included in the range of type1
758 -- size of type1 is at least twice the result size of op
760 -- then we don't do an overflow check in any case, instead we transform
761 -- the operation so that we end up with:
763 -- type1 (type1 (x) op type1 (y))
765 -- This avoids intermediate overflow before the conversion. It is
766 -- explicitly permitted by RM 3.5.4(24):
768 -- For the execution of a predefined operation of a signed integer
769 -- type, the implementation need not raise Constraint_Error if the
770 -- result is outside the base range of the type, so long as the
771 -- correct result is produced.
773 -- It's hard to imagine that any programmer counts on the exception
774 -- being raised in this case, and in any case it's wrong coding to
775 -- have this expectation, given the RM permission. Furthermore, other
776 -- Ada compilers do allow such out of range results.
778 -- Note that we do this transformation even if overflow checking is
779 -- off, since this is precisely about giving the "right" result and
780 -- avoiding the need for an overflow check.
782 -- Note: this circuit is partially redundant with respect to the similar
783 -- processing in Exp_Ch4.Expand_N_Type_Conversion, but the latter deals
784 -- with cases that do not come through here. We still need the following
785 -- processing even with the Exp_Ch4 code in place, since we want to be
786 -- sure not to generate the arithmetic overflow check in these cases
787 -- (Exp_Ch4 would have a hard time removing them once generated).
789 if Is_Signed_Integer_Type (Typ)
790 and then Nkind (Parent (N)) = N_Type_Conversion
793 Target_Type : constant Entity_Id :=
794 Base_Type (Entity (Subtype_Mark (Parent (N))));
808 if Is_Integer_Type (Target_Type)
809 and then RM_Size (Root_Type (Target_Type)) >= 2 * RM_Size (Rtyp)
811 Tlo := Expr_Value (Type_Low_Bound (Target_Type));
812 Thi := Expr_Value (Type_High_Bound (Target_Type));
815 (Left_Opnd (N), LOK, Llo, Lhi, Assume_Valid => True);
817 (Right_Opnd (N), ROK, Rlo, Rhi, Assume_Valid => True);
820 and then Tlo <= Llo and then Lhi <= Thi
821 and then Tlo <= Rlo and then Rhi <= Thi
823 Determine_Range (N, VOK, Vlo, Vhi, Assume_Valid => True);
825 if VOK and then Tlo <= Vlo and then Vhi <= Thi then
826 Rewrite (Left_Opnd (N),
827 Make_Type_Conversion (Loc,
828 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
829 Expression => Relocate_Node (Left_Opnd (N))));
831 Rewrite (Right_Opnd (N),
832 Make_Type_Conversion (Loc,
833 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
834 Expression => Relocate_Node (Right_Opnd (N))));
836 -- Rewrite the conversion operand so that the original
837 -- node is retained, in order to avoid the warning for
838 -- redundant conversions in Resolve_Type_Conversion.
840 Rewrite (N, Relocate_Node (N));
842 Set_Etype (N, Target_Type);
844 Analyze_And_Resolve (Left_Opnd (N), Target_Type);
845 Analyze_And_Resolve (Right_Opnd (N), Target_Type);
847 -- Given that the target type is twice the size of the
848 -- source type, overflow is now impossible, so we can
849 -- safely kill the overflow check and return.
851 Set_Do_Overflow_Check (N, False);
859 -- Now see if an overflow check is required
862 Siz : constant Int := UI_To_Int (Esize (Rtyp));
863 Dsiz : constant Int := Siz * 2;
870 -- Skip check if back end does overflow checks, or the overflow flag
871 -- is not set anyway, or we are not doing code expansion, or the
872 -- parent node is a type conversion whose operand is an arithmetic
873 -- operation on signed integers on which the expander can promote
874 -- later the operands to type Integer (see Expand_N_Type_Conversion).
876 -- Special case CLI target, where arithmetic overflow checks can be
877 -- performed for integer and long_integer
879 if Backend_Overflow_Checks_On_Target
880 or else not Do_Overflow_Check (N)
881 or else not Full_Expander_Active
882 or else (Present (Parent (N))
883 and then Nkind (Parent (N)) = N_Type_Conversion
884 and then Integer_Promotion_Possible (Parent (N)))
886 (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
891 -- Otherwise, generate the full general code for front end overflow
892 -- detection, which works by doing arithmetic in a larger type:
898 -- Typ (Checktyp (x) op Checktyp (y));
900 -- where Typ is the type of the original expression, and Checktyp is
901 -- an integer type of sufficient length to hold the largest possible
904 -- If the size of check type exceeds the size of Long_Long_Integer,
905 -- we use a different approach, expanding to:
907 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
909 -- where xxx is Add, Multiply or Subtract as appropriate
911 -- Find check type if one exists
913 if Dsiz <= Standard_Integer_Size then
914 Ctyp := Standard_Integer;
916 elsif Dsiz <= Standard_Long_Long_Integer_Size then
917 Ctyp := Standard_Long_Long_Integer;
919 -- No check type exists, use runtime call
922 if Nkind (N) = N_Op_Add then
923 Cent := RE_Add_With_Ovflo_Check;
925 elsif Nkind (N) = N_Op_Multiply then
926 Cent := RE_Multiply_With_Ovflo_Check;
929 pragma Assert (Nkind (N) = N_Op_Subtract);
930 Cent := RE_Subtract_With_Ovflo_Check;
935 Make_Function_Call (Loc,
936 Name => New_Reference_To (RTE (Cent), Loc),
937 Parameter_Associations => New_List (
938 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
939 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
941 Analyze_And_Resolve (N, Typ);
945 -- If we fall through, we have the case where we do the arithmetic
946 -- in the next higher type and get the check by conversion. In these
947 -- cases Ctyp is set to the type to be used as the check type.
949 Opnod := Relocate_Node (N);
951 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
954 Set_Etype (Opnd, Ctyp);
955 Set_Analyzed (Opnd, True);
956 Set_Left_Opnd (Opnod, Opnd);
958 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
961 Set_Etype (Opnd, Ctyp);
962 Set_Analyzed (Opnd, True);
963 Set_Right_Opnd (Opnod, Opnd);
965 -- The type of the operation changes to the base type of the check
966 -- type, and we reset the overflow check indication, since clearly no
967 -- overflow is possible now that we are using a double length type.
968 -- We also set the Analyzed flag to avoid a recursive attempt to
971 Set_Etype (Opnod, Base_Type (Ctyp));
972 Set_Do_Overflow_Check (Opnod, False);
973 Set_Analyzed (Opnod, True);
975 -- Now build the outer conversion
977 Opnd := OK_Convert_To (Typ, Opnod);
979 Set_Etype (Opnd, Typ);
981 -- In the discrete type case, we directly generate the range check
982 -- for the outer operand. This range check will implement the
983 -- required overflow check.
985 if Is_Discrete_Type (Typ) then
988 (Expression (N), Typ, CE_Overflow_Check_Failed);
990 -- For other types, we enable overflow checking on the conversion,
991 -- after setting the node as analyzed to prevent recursive attempts
992 -- to expand the conversion node.
995 Set_Analyzed (Opnd, True);
996 Enable_Overflow_Check (Opnd);
1001 when RE_Not_Available =>
1004 end Apply_Arithmetic_Overflow_Check;
1006 ----------------------------
1007 -- Apply_Constraint_Check --
1008 ----------------------------
1010 procedure Apply_Constraint_Check
1013 No_Sliding : Boolean := False)
1015 Desig_Typ : Entity_Id;
1018 -- No checks inside a generic (check the instantiations)
1020 if Inside_A_Generic then
1024 -- Apply required constraint checks
1026 if Is_Scalar_Type (Typ) then
1027 Apply_Scalar_Range_Check (N, Typ);
1029 elsif Is_Array_Type (Typ) then
1031 -- A useful optimization: an aggregate with only an others clause
1032 -- always has the right bounds.
1034 if Nkind (N) = N_Aggregate
1035 and then No (Expressions (N))
1037 (First (Choices (First (Component_Associations (N)))))
1043 if Is_Constrained (Typ) then
1044 Apply_Length_Check (N, Typ);
1047 Apply_Range_Check (N, Typ);
1050 Apply_Range_Check (N, Typ);
1053 elsif (Is_Record_Type (Typ)
1054 or else Is_Private_Type (Typ))
1055 and then Has_Discriminants (Base_Type (Typ))
1056 and then Is_Constrained (Typ)
1058 Apply_Discriminant_Check (N, Typ);
1060 elsif Is_Access_Type (Typ) then
1062 Desig_Typ := Designated_Type (Typ);
1064 -- No checks necessary if expression statically null
1066 if Known_Null (N) then
1067 if Can_Never_Be_Null (Typ) then
1068 Install_Null_Excluding_Check (N);
1071 -- No sliding possible on access to arrays
1073 elsif Is_Array_Type (Desig_Typ) then
1074 if Is_Constrained (Desig_Typ) then
1075 Apply_Length_Check (N, Typ);
1078 Apply_Range_Check (N, Typ);
1080 elsif Has_Discriminants (Base_Type (Desig_Typ))
1081 and then Is_Constrained (Desig_Typ)
1083 Apply_Discriminant_Check (N, Typ);
1086 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1087 -- this check if the constraint node is illegal, as shown by having
1088 -- an error posted. This additional guard prevents cascaded errors
1089 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1091 if Can_Never_Be_Null (Typ)
1092 and then not Can_Never_Be_Null (Etype (N))
1093 and then not Error_Posted (N)
1095 Install_Null_Excluding_Check (N);
1098 end Apply_Constraint_Check;
1100 ------------------------------
1101 -- Apply_Discriminant_Check --
1102 ------------------------------
1104 procedure Apply_Discriminant_Check
1107 Lhs : Node_Id := Empty)
1109 Loc : constant Source_Ptr := Sloc (N);
1110 Do_Access : constant Boolean := Is_Access_Type (Typ);
1111 S_Typ : Entity_Id := Etype (N);
1115 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean;
1116 -- A heap object with an indefinite subtype is constrained by its
1117 -- initial value, and assigning to it requires a constraint_check.
1118 -- The target may be an explicit dereference, or a renaming of one.
1120 function Is_Aliased_Unconstrained_Component return Boolean;
1121 -- It is possible for an aliased component to have a nominal
1122 -- unconstrained subtype (through instantiation). If this is a
1123 -- discriminated component assigned in the expansion of an aggregate
1124 -- in an initialization, the check must be suppressed. This unusual
1125 -- situation requires a predicate of its own.
1127 ----------------------------------
1128 -- Denotes_Explicit_Dereference --
1129 ----------------------------------
1131 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean is
1134 Nkind (Obj) = N_Explicit_Dereference
1136 (Is_Entity_Name (Obj)
1137 and then Present (Renamed_Object (Entity (Obj)))
1138 and then Nkind (Renamed_Object (Entity (Obj))) =
1139 N_Explicit_Dereference);
1140 end Denotes_Explicit_Dereference;
1142 ----------------------------------------
1143 -- Is_Aliased_Unconstrained_Component --
1144 ----------------------------------------
1146 function Is_Aliased_Unconstrained_Component return Boolean is
1151 if Nkind (Lhs) /= N_Selected_Component then
1154 Comp := Entity (Selector_Name (Lhs));
1155 Pref := Prefix (Lhs);
1158 if Ekind (Comp) /= E_Component
1159 or else not Is_Aliased (Comp)
1164 return not Comes_From_Source (Pref)
1165 and then In_Instance
1166 and then not Is_Constrained (Etype (Comp));
1167 end Is_Aliased_Unconstrained_Component;
1169 -- Start of processing for Apply_Discriminant_Check
1173 T_Typ := Designated_Type (Typ);
1178 -- Nothing to do if discriminant checks are suppressed or else no code
1179 -- is to be generated
1181 if not Full_Expander_Active
1182 or else Discriminant_Checks_Suppressed (T_Typ)
1187 -- No discriminant checks necessary for an access when expression is
1188 -- statically Null. This is not only an optimization, it is fundamental
1189 -- because otherwise discriminant checks may be generated in init procs
1190 -- for types containing an access to a not-yet-frozen record, causing a
1191 -- deadly forward reference.
1193 -- Also, if the expression is of an access type whose designated type is
1194 -- incomplete, then the access value must be null and we suppress the
1197 if Known_Null (N) then
1200 elsif Is_Access_Type (S_Typ) then
1201 S_Typ := Designated_Type (S_Typ);
1203 if Ekind (S_Typ) = E_Incomplete_Type then
1208 -- If an assignment target is present, then we need to generate the
1209 -- actual subtype if the target is a parameter or aliased object with
1210 -- an unconstrained nominal subtype.
1212 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1213 -- subtype to the parameter and dereference cases, since other aliased
1214 -- objects are unconstrained (unless the nominal subtype is explicitly
1218 and then (Present (Param_Entity (Lhs))
1219 or else (Ada_Version < Ada_2005
1220 and then not Is_Constrained (T_Typ)
1221 and then Is_Aliased_View (Lhs)
1222 and then not Is_Aliased_Unconstrained_Component)
1223 or else (Ada_Version >= Ada_2005
1224 and then not Is_Constrained (T_Typ)
1225 and then Denotes_Explicit_Dereference (Lhs)
1226 and then Nkind (Original_Node (Lhs)) /=
1229 T_Typ := Get_Actual_Subtype (Lhs);
1232 -- Nothing to do if the type is unconstrained (this is the case where
1233 -- the actual subtype in the RM sense of N is unconstrained and no check
1236 if not Is_Constrained (T_Typ) then
1239 -- Ada 2005: nothing to do if the type is one for which there is a
1240 -- partial view that is constrained.
1242 elsif Ada_Version >= Ada_2005
1243 and then Has_Constrained_Partial_View (Base_Type (T_Typ))
1248 -- Nothing to do if the type is an Unchecked_Union
1250 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1254 -- Suppress checks if the subtypes are the same. the check must be
1255 -- preserved in an assignment to a formal, because the constraint is
1256 -- given by the actual.
1258 if Nkind (Original_Node (N)) /= N_Allocator
1260 or else not Is_Entity_Name (Lhs)
1261 or else No (Param_Entity (Lhs)))
1264 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1265 and then not Is_Aliased_View (Lhs)
1270 -- We can also eliminate checks on allocators with a subtype mark that
1271 -- coincides with the context type. The context type may be a subtype
1272 -- without a constraint (common case, a generic actual).
1274 elsif Nkind (Original_Node (N)) = N_Allocator
1275 and then Is_Entity_Name (Expression (Original_Node (N)))
1278 Alloc_Typ : constant Entity_Id :=
1279 Entity (Expression (Original_Node (N)));
1282 if Alloc_Typ = T_Typ
1283 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1284 and then Is_Entity_Name (
1285 Subtype_Indication (Parent (T_Typ)))
1286 and then Alloc_Typ = Base_Type (T_Typ))
1294 -- See if we have a case where the types are both constrained, and all
1295 -- the constraints are constants. In this case, we can do the check
1296 -- successfully at compile time.
1298 -- We skip this check for the case where the node is a rewritten`
1299 -- allocator, because it already carries the context subtype, and
1300 -- extracting the discriminants from the aggregate is messy.
1302 if Is_Constrained (S_Typ)
1303 and then Nkind (Original_Node (N)) /= N_Allocator
1313 -- S_Typ may not have discriminants in the case where it is a
1314 -- private type completed by a default discriminated type. In that
1315 -- case, we need to get the constraints from the underlying_type.
1316 -- If the underlying type is unconstrained (i.e. has no default
1317 -- discriminants) no check is needed.
1319 if Has_Discriminants (S_Typ) then
1320 Discr := First_Discriminant (S_Typ);
1321 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1324 Discr := First_Discriminant (Underlying_Type (S_Typ));
1327 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1333 -- A further optimization: if T_Typ is derived from S_Typ
1334 -- without imposing a constraint, no check is needed.
1336 if Nkind (Original_Node (Parent (T_Typ))) =
1337 N_Full_Type_Declaration
1340 Type_Def : constant Node_Id :=
1342 (Original_Node (Parent (T_Typ)));
1344 if Nkind (Type_Def) = N_Derived_Type_Definition
1345 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1346 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1354 DconT := First_Elmt (Discriminant_Constraint (T_Typ));
1356 while Present (Discr) loop
1357 ItemS := Node (DconS);
1358 ItemT := Node (DconT);
1360 -- For a discriminated component type constrained by the
1361 -- current instance of an enclosing type, there is no
1362 -- applicable discriminant check.
1364 if Nkind (ItemT) = N_Attribute_Reference
1365 and then Is_Access_Type (Etype (ItemT))
1366 and then Is_Entity_Name (Prefix (ItemT))
1367 and then Is_Type (Entity (Prefix (ItemT)))
1372 -- If the expressions for the discriminants are identical
1373 -- and it is side-effect free (for now just an entity),
1374 -- this may be a shared constraint, e.g. from a subtype
1375 -- without a constraint introduced as a generic actual.
1376 -- Examine other discriminants if any.
1379 and then Is_Entity_Name (ItemS)
1383 elsif not Is_OK_Static_Expression (ItemS)
1384 or else not Is_OK_Static_Expression (ItemT)
1388 elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
1389 if Do_Access then -- needs run-time check.
1392 Apply_Compile_Time_Constraint_Error
1393 (N, "incorrect value for discriminant&?",
1394 CE_Discriminant_Check_Failed, Ent => Discr);
1401 Next_Discriminant (Discr);
1410 -- Here we need a discriminant check. First build the expression
1411 -- for the comparisons of the discriminants:
1413 -- (n.disc1 /= typ.disc1) or else
1414 -- (n.disc2 /= typ.disc2) or else
1416 -- (n.discn /= typ.discn)
1418 Cond := Build_Discriminant_Checks (N, T_Typ);
1420 -- If Lhs is set and is a parameter, then the condition is
1421 -- guarded by: lhs'constrained and then (condition built above)
1423 if Present (Param_Entity (Lhs)) then
1427 Make_Attribute_Reference (Loc,
1428 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1429 Attribute_Name => Name_Constrained),
1430 Right_Opnd => Cond);
1434 Cond := Guard_Access (Cond, Loc, N);
1438 Make_Raise_Constraint_Error (Loc,
1440 Reason => CE_Discriminant_Check_Failed));
1441 end Apply_Discriminant_Check;
1443 ------------------------
1444 -- Apply_Divide_Check --
1445 ------------------------
1447 procedure Apply_Divide_Check (N : Node_Id) is
1448 Loc : constant Source_Ptr := Sloc (N);
1449 Typ : constant Entity_Id := Etype (N);
1450 Left : constant Node_Id := Left_Opnd (N);
1451 Right : constant Node_Id := Right_Opnd (N);
1461 pragma Warnings (Off, Lhi);
1462 -- Don't actually use this value
1465 if Full_Expander_Active
1466 and then not Backend_Divide_Checks_On_Target
1467 and then Check_Needed (Right, Division_Check)
1469 Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True);
1471 -- See if division by zero possible, and if so generate test. This
1472 -- part of the test is not controlled by the -gnato switch.
1474 if Do_Division_Check (N) then
1475 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1477 Make_Raise_Constraint_Error (Loc,
1480 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1481 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1482 Reason => CE_Divide_By_Zero));
1486 -- Test for extremely annoying case of xxx'First divided by -1
1488 if Do_Overflow_Check (N) then
1489 if Nkind (N) = N_Op_Divide
1490 and then Is_Signed_Integer_Type (Typ)
1492 Determine_Range (Left, LOK, Llo, Lhi, Assume_Valid => True);
1493 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1495 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1497 ((not LOK) or else (Llo = LLB))
1500 Make_Raise_Constraint_Error (Loc,
1506 Duplicate_Subexpr_Move_Checks (Left),
1507 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1511 Duplicate_Subexpr (Right),
1513 Make_Integer_Literal (Loc, -1))),
1514 Reason => CE_Overflow_Check_Failed));
1519 end Apply_Divide_Check;
1521 ----------------------------------
1522 -- Apply_Float_Conversion_Check --
1523 ----------------------------------
1525 -- Let F and I be the source and target types of the conversion. The RM
1526 -- specifies that a floating-point value X is rounded to the nearest
1527 -- integer, with halfway cases being rounded away from zero. The rounded
1528 -- value of X is checked against I'Range.
1530 -- The catch in the above paragraph is that there is no good way to know
1531 -- whether the round-to-integer operation resulted in overflow. A remedy is
1532 -- to perform a range check in the floating-point domain instead, however:
1534 -- (1) The bounds may not be known at compile time
1535 -- (2) The check must take into account rounding or truncation.
1536 -- (3) The range of type I may not be exactly representable in F.
1537 -- (4) For the rounding case, The end-points I'First - 0.5 and
1538 -- I'Last + 0.5 may or may not be in range, depending on the
1539 -- sign of I'First and I'Last.
1540 -- (5) X may be a NaN, which will fail any comparison
1542 -- The following steps correctly convert X with rounding:
1544 -- (1) If either I'First or I'Last is not known at compile time, use
1545 -- I'Base instead of I in the next three steps and perform a
1546 -- regular range check against I'Range after conversion.
1547 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1548 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1549 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1550 -- In other words, take one of the closest floating-point numbers
1551 -- (which is an integer value) to I'First, and see if it is in
1553 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1554 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1555 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1556 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1557 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1559 -- For the truncating case, replace steps (2) and (3) as follows:
1560 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1561 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1563 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1564 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1567 procedure Apply_Float_Conversion_Check
1569 Target_Typ : Entity_Id)
1571 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1572 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1573 Loc : constant Source_Ptr := Sloc (Ck_Node);
1574 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1575 Target_Base : constant Entity_Id :=
1576 Implementation_Base_Type (Target_Typ);
1578 Par : constant Node_Id := Parent (Ck_Node);
1579 pragma Assert (Nkind (Par) = N_Type_Conversion);
1580 -- Parent of check node, must be a type conversion
1582 Truncate : constant Boolean := Float_Truncate (Par);
1583 Max_Bound : constant Uint :=
1585 (Machine_Radix_Value (Expr_Type),
1586 Machine_Mantissa_Value (Expr_Type) - 1) - 1;
1588 -- Largest bound, so bound plus or minus half is a machine number of F
1590 Ifirst, Ilast : Uint;
1591 -- Bounds of integer type
1594 -- Bounds to check in floating-point domain
1596 Lo_OK, Hi_OK : Boolean;
1597 -- True iff Lo resp. Hi belongs to I'Range
1599 Lo_Chk, Hi_Chk : Node_Id;
1600 -- Expressions that are False iff check fails
1602 Reason : RT_Exception_Code;
1605 if not Compile_Time_Known_Value (LB)
1606 or not Compile_Time_Known_Value (HB)
1609 -- First check that the value falls in the range of the base type,
1610 -- to prevent overflow during conversion and then perform a
1611 -- regular range check against the (dynamic) bounds.
1613 pragma Assert (Target_Base /= Target_Typ);
1615 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Par);
1618 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1619 Set_Etype (Temp, Target_Base);
1621 Insert_Action (Parent (Par),
1622 Make_Object_Declaration (Loc,
1623 Defining_Identifier => Temp,
1624 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1625 Expression => New_Copy_Tree (Par)),
1626 Suppress => All_Checks);
1629 Make_Raise_Constraint_Error (Loc,
1632 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1633 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1634 Reason => CE_Range_Check_Failed));
1635 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
1641 -- Get the (static) bounds of the target type
1643 Ifirst := Expr_Value (LB);
1644 Ilast := Expr_Value (HB);
1646 -- A simple optimization: if the expression is a universal literal,
1647 -- we can do the comparison with the bounds and the conversion to
1648 -- an integer type statically. The range checks are unchanged.
1650 if Nkind (Ck_Node) = N_Real_Literal
1651 and then Etype (Ck_Node) = Universal_Real
1652 and then Is_Integer_Type (Target_Typ)
1653 and then Nkind (Parent (Ck_Node)) = N_Type_Conversion
1656 Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node));
1659 if Int_Val <= Ilast and then Int_Val >= Ifirst then
1661 -- Conversion is safe
1663 Rewrite (Parent (Ck_Node),
1664 Make_Integer_Literal (Loc, UI_To_Int (Int_Val)));
1665 Analyze_And_Resolve (Parent (Ck_Node), Target_Typ);
1671 -- Check against lower bound
1673 if Truncate and then Ifirst > 0 then
1674 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
1678 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
1681 elsif abs (Ifirst) < Max_Bound then
1682 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
1683 Lo_OK := (Ifirst > 0);
1686 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
1687 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
1692 -- Lo_Chk := (X >= Lo)
1694 Lo_Chk := Make_Op_Ge (Loc,
1695 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1696 Right_Opnd => Make_Real_Literal (Loc, Lo));
1699 -- Lo_Chk := (X > Lo)
1701 Lo_Chk := Make_Op_Gt (Loc,
1702 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1703 Right_Opnd => Make_Real_Literal (Loc, Lo));
1706 -- Check against higher bound
1708 if Truncate and then Ilast < 0 then
1709 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
1713 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
1716 elsif abs (Ilast) < Max_Bound then
1717 Hi := UR_From_Uint (Ilast) + Ureal_Half;
1718 Hi_OK := (Ilast < 0);
1720 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
1721 Hi_OK := (Hi <= UR_From_Uint (Ilast));
1726 -- Hi_Chk := (X <= Hi)
1728 Hi_Chk := Make_Op_Le (Loc,
1729 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1730 Right_Opnd => Make_Real_Literal (Loc, Hi));
1733 -- Hi_Chk := (X < Hi)
1735 Hi_Chk := Make_Op_Lt (Loc,
1736 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1737 Right_Opnd => Make_Real_Literal (Loc, Hi));
1740 -- If the bounds of the target type are the same as those of the base
1741 -- type, the check is an overflow check as a range check is not
1742 -- performed in these cases.
1744 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
1745 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
1747 Reason := CE_Overflow_Check_Failed;
1749 Reason := CE_Range_Check_Failed;
1752 -- Raise CE if either conditions does not hold
1754 Insert_Action (Ck_Node,
1755 Make_Raise_Constraint_Error (Loc,
1756 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
1758 end Apply_Float_Conversion_Check;
1760 ------------------------
1761 -- Apply_Length_Check --
1762 ------------------------
1764 procedure Apply_Length_Check
1766 Target_Typ : Entity_Id;
1767 Source_Typ : Entity_Id := Empty)
1770 Apply_Selected_Length_Checks
1771 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1772 end Apply_Length_Check;
1774 ---------------------------
1775 -- Apply_Predicate_Check --
1776 ---------------------------
1778 procedure Apply_Predicate_Check (N : Node_Id; Typ : Entity_Id) is
1780 if Present (Predicate_Function (Typ)) then
1782 Make_Predicate_Check (Typ, Duplicate_Subexpr (N)));
1784 end Apply_Predicate_Check;
1786 -----------------------
1787 -- Apply_Range_Check --
1788 -----------------------
1790 procedure Apply_Range_Check
1792 Target_Typ : Entity_Id;
1793 Source_Typ : Entity_Id := Empty)
1796 Apply_Selected_Range_Checks
1797 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1798 end Apply_Range_Check;
1800 ------------------------------
1801 -- Apply_Scalar_Range_Check --
1802 ------------------------------
1804 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
1805 -- off if it is already set on.
1807 procedure Apply_Scalar_Range_Check
1809 Target_Typ : Entity_Id;
1810 Source_Typ : Entity_Id := Empty;
1811 Fixed_Int : Boolean := False)
1813 Parnt : constant Node_Id := Parent (Expr);
1815 Arr : Node_Id := Empty; -- initialize to prevent warning
1816 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
1819 Is_Subscr_Ref : Boolean;
1820 -- Set true if Expr is a subscript
1822 Is_Unconstrained_Subscr_Ref : Boolean;
1823 -- Set true if Expr is a subscript of an unconstrained array. In this
1824 -- case we do not attempt to do an analysis of the value against the
1825 -- range of the subscript, since we don't know the actual subtype.
1828 -- Set to True if Expr should be regarded as a real value even though
1829 -- the type of Expr might be discrete.
1831 procedure Bad_Value;
1832 -- Procedure called if value is determined to be out of range
1838 procedure Bad_Value is
1840 Apply_Compile_Time_Constraint_Error
1841 (Expr, "value not in range of}?", CE_Range_Check_Failed,
1846 -- Start of processing for Apply_Scalar_Range_Check
1849 -- Return if check obviously not needed
1852 -- Not needed inside generic
1856 -- Not needed if previous error
1858 or else Target_Typ = Any_Type
1859 or else Nkind (Expr) = N_Error
1861 -- Not needed for non-scalar type
1863 or else not Is_Scalar_Type (Target_Typ)
1865 -- Not needed if we know node raises CE already
1867 or else Raises_Constraint_Error (Expr)
1872 -- Now, see if checks are suppressed
1875 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
1877 if Is_Subscr_Ref then
1878 Arr := Prefix (Parnt);
1879 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
1881 if Is_Access_Type (Arr_Typ) then
1882 Arr_Typ := Designated_Type (Arr_Typ);
1886 if not Do_Range_Check (Expr) then
1888 -- Subscript reference. Check for Index_Checks suppressed
1890 if Is_Subscr_Ref then
1892 -- Check array type and its base type
1894 if Index_Checks_Suppressed (Arr_Typ)
1895 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
1899 -- Check array itself if it is an entity name
1901 elsif Is_Entity_Name (Arr)
1902 and then Index_Checks_Suppressed (Entity (Arr))
1906 -- Check expression itself if it is an entity name
1908 elsif Is_Entity_Name (Expr)
1909 and then Index_Checks_Suppressed (Entity (Expr))
1914 -- All other cases, check for Range_Checks suppressed
1917 -- Check target type and its base type
1919 if Range_Checks_Suppressed (Target_Typ)
1920 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
1924 -- Check expression itself if it is an entity name
1926 elsif Is_Entity_Name (Expr)
1927 and then Range_Checks_Suppressed (Entity (Expr))
1931 -- If Expr is part of an assignment statement, then check left
1932 -- side of assignment if it is an entity name.
1934 elsif Nkind (Parnt) = N_Assignment_Statement
1935 and then Is_Entity_Name (Name (Parnt))
1936 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
1943 -- Do not set range checks if they are killed
1945 if Nkind (Expr) = N_Unchecked_Type_Conversion
1946 and then Kill_Range_Check (Expr)
1951 -- Do not set range checks for any values from System.Scalar_Values
1952 -- since the whole idea of such values is to avoid checking them!
1954 if Is_Entity_Name (Expr)
1955 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
1960 -- Now see if we need a check
1962 if No (Source_Typ) then
1963 S_Typ := Etype (Expr);
1965 S_Typ := Source_Typ;
1968 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
1972 Is_Unconstrained_Subscr_Ref :=
1973 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
1975 -- Always do a range check if the source type includes infinities and
1976 -- the target type does not include infinities. We do not do this if
1977 -- range checks are killed.
1979 if Is_Floating_Point_Type (S_Typ)
1980 and then Has_Infinities (S_Typ)
1981 and then not Has_Infinities (Target_Typ)
1983 Enable_Range_Check (Expr);
1986 -- Return if we know expression is definitely in the range of the target
1987 -- type as determined by Determine_Range. Right now we only do this for
1988 -- discrete types, and not fixed-point or floating-point types.
1990 -- The additional less-precise tests below catch these cases
1992 -- Note: skip this if we are given a source_typ, since the point of
1993 -- supplying a Source_Typ is to stop us looking at the expression.
1994 -- We could sharpen this test to be out parameters only ???
1996 if Is_Discrete_Type (Target_Typ)
1997 and then Is_Discrete_Type (Etype (Expr))
1998 and then not Is_Unconstrained_Subscr_Ref
1999 and then No (Source_Typ)
2002 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
2003 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
2008 if Compile_Time_Known_Value (Tlo)
2009 and then Compile_Time_Known_Value (Thi)
2012 Lov : constant Uint := Expr_Value (Tlo);
2013 Hiv : constant Uint := Expr_Value (Thi);
2016 -- If range is null, we for sure have a constraint error
2017 -- (we don't even need to look at the value involved,
2018 -- since all possible values will raise CE).
2025 -- Otherwise determine range of value
2027 Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True);
2031 -- If definitely in range, all OK
2033 if Lo >= Lov and then Hi <= Hiv then
2036 -- If definitely not in range, warn
2038 elsif Lov > Hi or else Hiv < Lo then
2042 -- Otherwise we don't know
2054 Is_Floating_Point_Type (S_Typ)
2055 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
2057 -- Check if we can determine at compile time whether Expr is in the
2058 -- range of the target type. Note that if S_Typ is within the bounds
2059 -- of Target_Typ then this must be the case. This check is meaningful
2060 -- only if this is not a conversion between integer and real types.
2062 if not Is_Unconstrained_Subscr_Ref
2064 Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
2066 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
2068 Is_In_Range (Expr, Target_Typ,
2069 Assume_Valid => True,
2070 Fixed_Int => Fixed_Int,
2071 Int_Real => Int_Real))
2075 elsif Is_Out_Of_Range (Expr, Target_Typ,
2076 Assume_Valid => True,
2077 Fixed_Int => Fixed_Int,
2078 Int_Real => Int_Real)
2083 -- In the floating-point case, we only do range checks if the type is
2084 -- constrained. We definitely do NOT want range checks for unconstrained
2085 -- types, since we want to have infinities
2087 elsif Is_Floating_Point_Type (S_Typ) then
2088 if Is_Constrained (S_Typ) then
2089 Enable_Range_Check (Expr);
2092 -- For all other cases we enable a range check unconditionally
2095 Enable_Range_Check (Expr);
2098 end Apply_Scalar_Range_Check;
2100 ----------------------------------
2101 -- Apply_Selected_Length_Checks --
2102 ----------------------------------
2104 procedure Apply_Selected_Length_Checks
2106 Target_Typ : Entity_Id;
2107 Source_Typ : Entity_Id;
2108 Do_Static : Boolean)
2111 R_Result : Check_Result;
2114 Loc : constant Source_Ptr := Sloc (Ck_Node);
2115 Checks_On : constant Boolean :=
2116 (not Index_Checks_Suppressed (Target_Typ))
2118 (not Length_Checks_Suppressed (Target_Typ));
2121 if not Full_Expander_Active then
2126 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2128 for J in 1 .. 2 loop
2129 R_Cno := R_Result (J);
2130 exit when No (R_Cno);
2132 -- A length check may mention an Itype which is attached to a
2133 -- subsequent node. At the top level in a package this can cause
2134 -- an order-of-elaboration problem, so we make sure that the itype
2135 -- is referenced now.
2137 if Ekind (Current_Scope) = E_Package
2138 and then Is_Compilation_Unit (Current_Scope)
2140 Ensure_Defined (Target_Typ, Ck_Node);
2142 if Present (Source_Typ) then
2143 Ensure_Defined (Source_Typ, Ck_Node);
2145 elsif Is_Itype (Etype (Ck_Node)) then
2146 Ensure_Defined (Etype (Ck_Node), Ck_Node);
2150 -- If the item is a conditional raise of constraint error, then have
2151 -- a look at what check is being performed and ???
2153 if Nkind (R_Cno) = N_Raise_Constraint_Error
2154 and then Present (Condition (R_Cno))
2156 Cond := Condition (R_Cno);
2158 -- Case where node does not now have a dynamic check
2160 if not Has_Dynamic_Length_Check (Ck_Node) then
2162 -- If checks are on, just insert the check
2165 Insert_Action (Ck_Node, R_Cno);
2167 if not Do_Static then
2168 Set_Has_Dynamic_Length_Check (Ck_Node);
2171 -- If checks are off, then analyze the length check after
2172 -- temporarily attaching it to the tree in case the relevant
2173 -- condition can be evaluated at compile time. We still want a
2174 -- compile time warning in this case.
2177 Set_Parent (R_Cno, Ck_Node);
2182 -- Output a warning if the condition is known to be True
2184 if Is_Entity_Name (Cond)
2185 and then Entity (Cond) = Standard_True
2187 Apply_Compile_Time_Constraint_Error
2188 (Ck_Node, "wrong length for array of}?",
2189 CE_Length_Check_Failed,
2193 -- If we were only doing a static check, or if checks are not
2194 -- on, then we want to delete the check, since it is not needed.
2195 -- We do this by replacing the if statement by a null statement
2197 elsif Do_Static or else not Checks_On then
2198 Remove_Warning_Messages (R_Cno);
2199 Rewrite (R_Cno, Make_Null_Statement (Loc));
2203 Install_Static_Check (R_Cno, Loc);
2206 end Apply_Selected_Length_Checks;
2208 ---------------------------------
2209 -- Apply_Selected_Range_Checks --
2210 ---------------------------------
2212 procedure Apply_Selected_Range_Checks
2214 Target_Typ : Entity_Id;
2215 Source_Typ : Entity_Id;
2216 Do_Static : Boolean)
2219 R_Result : Check_Result;
2222 Loc : constant Source_Ptr := Sloc (Ck_Node);
2223 Checks_On : constant Boolean :=
2224 (not Index_Checks_Suppressed (Target_Typ))
2226 (not Range_Checks_Suppressed (Target_Typ));
2229 if not Full_Expander_Active or else not Checks_On then
2234 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2236 for J in 1 .. 2 loop
2238 R_Cno := R_Result (J);
2239 exit when No (R_Cno);
2241 -- If the item is a conditional raise of constraint error, then have
2242 -- a look at what check is being performed and ???
2244 if Nkind (R_Cno) = N_Raise_Constraint_Error
2245 and then Present (Condition (R_Cno))
2247 Cond := Condition (R_Cno);
2249 if not Has_Dynamic_Range_Check (Ck_Node) then
2250 Insert_Action (Ck_Node, R_Cno);
2252 if not Do_Static then
2253 Set_Has_Dynamic_Range_Check (Ck_Node);
2257 -- Output a warning if the condition is known to be True
2259 if Is_Entity_Name (Cond)
2260 and then Entity (Cond) = Standard_True
2262 -- Since an N_Range is technically not an expression, we have
2263 -- to set one of the bounds to C_E and then just flag the
2264 -- N_Range. The warning message will point to the lower bound
2265 -- and complain about a range, which seems OK.
2267 if Nkind (Ck_Node) = N_Range then
2268 Apply_Compile_Time_Constraint_Error
2269 (Low_Bound (Ck_Node), "static range out of bounds of}?",
2270 CE_Range_Check_Failed,
2274 Set_Raises_Constraint_Error (Ck_Node);
2277 Apply_Compile_Time_Constraint_Error
2278 (Ck_Node, "static value out of range of}?",
2279 CE_Range_Check_Failed,
2284 -- If we were only doing a static check, or if checks are not
2285 -- on, then we want to delete the check, since it is not needed.
2286 -- We do this by replacing the if statement by a null statement
2288 elsif Do_Static or else not Checks_On then
2289 Remove_Warning_Messages (R_Cno);
2290 Rewrite (R_Cno, Make_Null_Statement (Loc));
2294 Install_Static_Check (R_Cno, Loc);
2297 end Apply_Selected_Range_Checks;
2299 -------------------------------
2300 -- Apply_Static_Length_Check --
2301 -------------------------------
2303 procedure Apply_Static_Length_Check
2305 Target_Typ : Entity_Id;
2306 Source_Typ : Entity_Id := Empty)
2309 Apply_Selected_Length_Checks
2310 (Expr, Target_Typ, Source_Typ, Do_Static => True);
2311 end Apply_Static_Length_Check;
2313 -------------------------------------
2314 -- Apply_Subscript_Validity_Checks --
2315 -------------------------------------
2317 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
2321 pragma Assert (Nkind (Expr) = N_Indexed_Component);
2323 -- Loop through subscripts
2325 Sub := First (Expressions (Expr));
2326 while Present (Sub) loop
2328 -- Check one subscript. Note that we do not worry about enumeration
2329 -- type with holes, since we will convert the value to a Pos value
2330 -- for the subscript, and that convert will do the necessary validity
2333 Ensure_Valid (Sub, Holes_OK => True);
2335 -- Move to next subscript
2339 end Apply_Subscript_Validity_Checks;
2341 ----------------------------------
2342 -- Apply_Type_Conversion_Checks --
2343 ----------------------------------
2345 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
2346 Target_Type : constant Entity_Id := Etype (N);
2347 Target_Base : constant Entity_Id := Base_Type (Target_Type);
2348 Expr : constant Node_Id := Expression (N);
2350 Expr_Type : constant Entity_Id := Underlying_Type (Etype (Expr));
2351 -- Note: if Etype (Expr) is a private type without discriminants, its
2352 -- full view might have discriminants with defaults, so we need the
2353 -- full view here to retrieve the constraints.
2356 if Inside_A_Generic then
2359 -- Skip these checks if serious errors detected, there are some nasty
2360 -- situations of incomplete trees that blow things up.
2362 elsif Serious_Errors_Detected > 0 then
2365 -- Scalar type conversions of the form Target_Type (Expr) require a
2366 -- range check if we cannot be sure that Expr is in the base type of
2367 -- Target_Typ and also that Expr is in the range of Target_Typ. These
2368 -- are not quite the same condition from an implementation point of
2369 -- view, but clearly the second includes the first.
2371 elsif Is_Scalar_Type (Target_Type) then
2373 Conv_OK : constant Boolean := Conversion_OK (N);
2374 -- If the Conversion_OK flag on the type conversion is set and no
2375 -- floating point type is involved in the type conversion then
2376 -- fixed point values must be read as integral values.
2378 Float_To_Int : constant Boolean :=
2379 Is_Floating_Point_Type (Expr_Type)
2380 and then Is_Integer_Type (Target_Type);
2383 if not Overflow_Checks_Suppressed (Target_Base)
2385 In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK)
2386 and then not Float_To_Int
2388 Activate_Overflow_Check (N);
2391 if not Range_Checks_Suppressed (Target_Type)
2392 and then not Range_Checks_Suppressed (Expr_Type)
2394 if Float_To_Int then
2395 Apply_Float_Conversion_Check (Expr, Target_Type);
2397 Apply_Scalar_Range_Check
2398 (Expr, Target_Type, Fixed_Int => Conv_OK);
2403 elsif Comes_From_Source (N)
2404 and then not Discriminant_Checks_Suppressed (Target_Type)
2405 and then Is_Record_Type (Target_Type)
2406 and then Is_Derived_Type (Target_Type)
2407 and then not Is_Tagged_Type (Target_Type)
2408 and then not Is_Constrained (Target_Type)
2409 and then Present (Stored_Constraint (Target_Type))
2411 -- An unconstrained derived type may have inherited discriminant.
2412 -- Build an actual discriminant constraint list using the stored
2413 -- constraint, to verify that the expression of the parent type
2414 -- satisfies the constraints imposed by the (unconstrained!)
2415 -- derived type. This applies to value conversions, not to view
2416 -- conversions of tagged types.
2419 Loc : constant Source_Ptr := Sloc (N);
2421 Constraint : Elmt_Id;
2422 Discr_Value : Node_Id;
2425 New_Constraints : constant Elist_Id := New_Elmt_List;
2426 Old_Constraints : constant Elist_Id :=
2427 Discriminant_Constraint (Expr_Type);
2430 Constraint := First_Elmt (Stored_Constraint (Target_Type));
2431 while Present (Constraint) loop
2432 Discr_Value := Node (Constraint);
2434 if Is_Entity_Name (Discr_Value)
2435 and then Ekind (Entity (Discr_Value)) = E_Discriminant
2437 Discr := Corresponding_Discriminant (Entity (Discr_Value));
2440 and then Scope (Discr) = Base_Type (Expr_Type)
2442 -- Parent is constrained by new discriminant. Obtain
2443 -- Value of original discriminant in expression. If the
2444 -- new discriminant has been used to constrain more than
2445 -- one of the stored discriminants, this will provide the
2446 -- required consistency check.
2449 (Make_Selected_Component (Loc,
2451 Duplicate_Subexpr_No_Checks
2452 (Expr, Name_Req => True),
2454 Make_Identifier (Loc, Chars (Discr))),
2458 -- Discriminant of more remote ancestor ???
2463 -- Derived type definition has an explicit value for this
2464 -- stored discriminant.
2468 (Duplicate_Subexpr_No_Checks (Discr_Value),
2472 Next_Elmt (Constraint);
2475 -- Use the unconstrained expression type to retrieve the
2476 -- discriminants of the parent, and apply momentarily the
2477 -- discriminant constraint synthesized above.
2479 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
2480 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
2481 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
2484 Make_Raise_Constraint_Error (Loc,
2486 Reason => CE_Discriminant_Check_Failed));
2489 -- For arrays, conversions are applied during expansion, to take into
2490 -- accounts changes of representation. The checks become range checks on
2491 -- the base type or length checks on the subtype, depending on whether
2492 -- the target type is unconstrained or constrained.
2497 end Apply_Type_Conversion_Checks;
2499 ----------------------------------------------
2500 -- Apply_Universal_Integer_Attribute_Checks --
2501 ----------------------------------------------
2503 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
2504 Loc : constant Source_Ptr := Sloc (N);
2505 Typ : constant Entity_Id := Etype (N);
2508 if Inside_A_Generic then
2511 -- Nothing to do if checks are suppressed
2513 elsif Range_Checks_Suppressed (Typ)
2514 and then Overflow_Checks_Suppressed (Typ)
2518 -- Nothing to do if the attribute does not come from source. The
2519 -- internal attributes we generate of this type do not need checks,
2520 -- and furthermore the attempt to check them causes some circular
2521 -- elaboration orders when dealing with packed types.
2523 elsif not Comes_From_Source (N) then
2526 -- If the prefix is a selected component that depends on a discriminant
2527 -- the check may improperly expose a discriminant instead of using
2528 -- the bounds of the object itself. Set the type of the attribute to
2529 -- the base type of the context, so that a check will be imposed when
2530 -- needed (e.g. if the node appears as an index).
2532 elsif Nkind (Prefix (N)) = N_Selected_Component
2533 and then Ekind (Typ) = E_Signed_Integer_Subtype
2534 and then Depends_On_Discriminant (Scalar_Range (Typ))
2536 Set_Etype (N, Base_Type (Typ));
2538 -- Otherwise, replace the attribute node with a type conversion node
2539 -- whose expression is the attribute, retyped to universal integer, and
2540 -- whose subtype mark is the target type. The call to analyze this
2541 -- conversion will set range and overflow checks as required for proper
2542 -- detection of an out of range value.
2545 Set_Etype (N, Universal_Integer);
2546 Set_Analyzed (N, True);
2549 Make_Type_Conversion (Loc,
2550 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
2551 Expression => Relocate_Node (N)));
2553 Analyze_And_Resolve (N, Typ);
2556 end Apply_Universal_Integer_Attribute_Checks;
2558 -------------------------------------
2559 -- Atomic_Synchronization_Disabled --
2560 -------------------------------------
2562 -- Note: internally Disable/Enable_Atomic_Synchronization is implemented
2563 -- using a bogus check called Atomic_Synchronization. This is to make it
2564 -- more convenient to get exactly the same semantics as [Un]Suppress.
2566 function Atomic_Synchronization_Disabled (E : Entity_Id) return Boolean is
2568 -- If debug flag d.e is set, always return False, i.e. all atomic sync
2569 -- looks enabled, since it is never disabled.
2571 if Debug_Flag_Dot_E then
2574 -- If debug flag d.d is set then always return True, i.e. all atomic
2575 -- sync looks disabled, since it always tests True.
2577 elsif Debug_Flag_Dot_D then
2580 -- If entity present, then check result for that entity
2582 elsif Present (E) and then Checks_May_Be_Suppressed (E) then
2583 return Is_Check_Suppressed (E, Atomic_Synchronization);
2585 -- Otherwise result depends on current scope setting
2588 return Scope_Suppress (Atomic_Synchronization);
2590 end Atomic_Synchronization_Disabled;
2592 -------------------------------
2593 -- Build_Discriminant_Checks --
2594 -------------------------------
2596 function Build_Discriminant_Checks
2598 T_Typ : Entity_Id) return Node_Id
2600 Loc : constant Source_Ptr := Sloc (N);
2603 Disc_Ent : Entity_Id;
2607 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
2609 ----------------------------------
2610 -- Aggregate_Discriminant_Value --
2611 ----------------------------------
2613 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
2617 -- The aggregate has been normalized with named associations. We use
2618 -- the Chars field to locate the discriminant to take into account
2619 -- discriminants in derived types, which carry the same name as those
2622 Assoc := First (Component_Associations (N));
2623 while Present (Assoc) loop
2624 if Chars (First (Choices (Assoc))) = Chars (Disc) then
2625 return Expression (Assoc);
2631 -- Discriminant must have been found in the loop above
2633 raise Program_Error;
2634 end Aggregate_Discriminant_Val;
2636 -- Start of processing for Build_Discriminant_Checks
2639 -- Loop through discriminants evolving the condition
2642 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
2644 -- For a fully private type, use the discriminants of the parent type
2646 if Is_Private_Type (T_Typ)
2647 and then No (Full_View (T_Typ))
2649 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
2651 Disc_Ent := First_Discriminant (T_Typ);
2654 while Present (Disc) loop
2655 Dval := Node (Disc);
2657 if Nkind (Dval) = N_Identifier
2658 and then Ekind (Entity (Dval)) = E_Discriminant
2660 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
2662 Dval := Duplicate_Subexpr_No_Checks (Dval);
2665 -- If we have an Unchecked_Union node, we can infer the discriminants
2668 if Is_Unchecked_Union (Base_Type (T_Typ)) then
2670 Get_Discriminant_Value (
2671 First_Discriminant (T_Typ),
2673 Stored_Constraint (T_Typ)));
2675 elsif Nkind (N) = N_Aggregate then
2677 Duplicate_Subexpr_No_Checks
2678 (Aggregate_Discriminant_Val (Disc_Ent));
2682 Make_Selected_Component (Loc,
2684 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
2686 Make_Identifier (Loc, Chars (Disc_Ent)));
2688 Set_Is_In_Discriminant_Check (Dref);
2691 Evolve_Or_Else (Cond,
2694 Right_Opnd => Dval));
2697 Next_Discriminant (Disc_Ent);
2701 end Build_Discriminant_Checks;
2707 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
2715 -- Always check if not simple entity
2717 if Nkind (Nod) not in N_Has_Entity
2718 or else not Comes_From_Source (Nod)
2723 -- Look up tree for short circuit
2730 -- Done if out of subexpression (note that we allow generated stuff
2731 -- such as itype declarations in this context, to keep the loop going
2732 -- since we may well have generated such stuff in complex situations.
2733 -- Also done if no parent (probably an error condition, but no point
2734 -- in behaving nasty if we find it!)
2737 or else (K not in N_Subexpr and then Comes_From_Source (P))
2741 -- Or/Or Else case, where test is part of the right operand, or is
2742 -- part of one of the actions associated with the right operand, and
2743 -- the left operand is an equality test.
2745 elsif K = N_Op_Or then
2746 exit when N = Right_Opnd (P)
2747 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2749 elsif K = N_Or_Else then
2750 exit when (N = Right_Opnd (P)
2753 and then List_Containing (N) = Actions (P)))
2754 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2756 -- Similar test for the And/And then case, where the left operand
2757 -- is an inequality test.
2759 elsif K = N_Op_And then
2760 exit when N = Right_Opnd (P)
2761 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2763 elsif K = N_And_Then then
2764 exit when (N = Right_Opnd (P)
2767 and then List_Containing (N) = Actions (P)))
2768 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2774 -- If we fall through the loop, then we have a conditional with an
2775 -- appropriate test as its left operand. So test further.
2778 R := Right_Opnd (L);
2781 -- Left operand of test must match original variable
2783 if Nkind (L) not in N_Has_Entity
2784 or else Entity (L) /= Entity (Nod)
2789 -- Right operand of test must be key value (zero or null)
2792 when Access_Check =>
2793 if not Known_Null (R) then
2797 when Division_Check =>
2798 if not Compile_Time_Known_Value (R)
2799 or else Expr_Value (R) /= Uint_0
2805 raise Program_Error;
2808 -- Here we have the optimizable case, warn if not short-circuited
2810 if K = N_Op_And or else K = N_Op_Or then
2812 when Access_Check =>
2814 ("Constraint_Error may be raised (access check)?",
2816 when Division_Check =>
2818 ("Constraint_Error may be raised (zero divide)?",
2822 raise Program_Error;
2825 if K = N_Op_And then
2826 Error_Msg_N -- CODEFIX
2827 ("use `AND THEN` instead of AND?", P);
2829 Error_Msg_N -- CODEFIX
2830 ("use `OR ELSE` instead of OR?", P);
2833 -- If not short-circuited, we need the check
2837 -- If short-circuited, we can omit the check
2844 -----------------------------------
2845 -- Check_Valid_Lvalue_Subscripts --
2846 -----------------------------------
2848 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
2850 -- Skip this if range checks are suppressed
2852 if Range_Checks_Suppressed (Etype (Expr)) then
2855 -- Only do this check for expressions that come from source. We assume
2856 -- that expander generated assignments explicitly include any necessary
2857 -- checks. Note that this is not just an optimization, it avoids
2858 -- infinite recursions!
2860 elsif not Comes_From_Source (Expr) then
2863 -- For a selected component, check the prefix
2865 elsif Nkind (Expr) = N_Selected_Component then
2866 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2869 -- Case of indexed component
2871 elsif Nkind (Expr) = N_Indexed_Component then
2872 Apply_Subscript_Validity_Checks (Expr);
2874 -- Prefix may itself be or contain an indexed component, and these
2875 -- subscripts need checking as well.
2877 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2879 end Check_Valid_Lvalue_Subscripts;
2881 ----------------------------------
2882 -- Null_Exclusion_Static_Checks --
2883 ----------------------------------
2885 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
2886 Error_Node : Node_Id;
2888 Has_Null : constant Boolean := Has_Null_Exclusion (N);
2889 K : constant Node_Kind := Nkind (N);
2894 (K = N_Component_Declaration
2895 or else K = N_Discriminant_Specification
2896 or else K = N_Function_Specification
2897 or else K = N_Object_Declaration
2898 or else K = N_Parameter_Specification);
2900 if K = N_Function_Specification then
2901 Typ := Etype (Defining_Entity (N));
2903 Typ := Etype (Defining_Identifier (N));
2907 when N_Component_Declaration =>
2908 if Present (Access_Definition (Component_Definition (N))) then
2909 Error_Node := Component_Definition (N);
2911 Error_Node := Subtype_Indication (Component_Definition (N));
2914 when N_Discriminant_Specification =>
2915 Error_Node := Discriminant_Type (N);
2917 when N_Function_Specification =>
2918 Error_Node := Result_Definition (N);
2920 when N_Object_Declaration =>
2921 Error_Node := Object_Definition (N);
2923 when N_Parameter_Specification =>
2924 Error_Node := Parameter_Type (N);
2927 raise Program_Error;
2932 -- Enforce legality rule 3.10 (13): A null exclusion can only be
2933 -- applied to an access [sub]type.
2935 if not Is_Access_Type (Typ) then
2937 ("`NOT NULL` allowed only for an access type", Error_Node);
2939 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
2940 -- be applied to a [sub]type that does not exclude null already.
2942 elsif Can_Never_Be_Null (Typ)
2943 and then Comes_From_Source (Typ)
2946 ("`NOT NULL` not allowed (& already excludes null)",
2951 -- Check that null-excluding objects are always initialized, except for
2952 -- deferred constants, for which the expression will appear in the full
2955 if K = N_Object_Declaration
2956 and then No (Expression (N))
2957 and then not Constant_Present (N)
2958 and then not No_Initialization (N)
2960 -- Add an expression that assigns null. This node is needed by
2961 -- Apply_Compile_Time_Constraint_Error, which will replace this with
2962 -- a Constraint_Error node.
2964 Set_Expression (N, Make_Null (Sloc (N)));
2965 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
2967 Apply_Compile_Time_Constraint_Error
2968 (N => Expression (N),
2969 Msg => "(Ada 2005) null-excluding objects must be initialized?",
2970 Reason => CE_Null_Not_Allowed);
2973 -- Check that a null-excluding component, formal or object is not being
2974 -- assigned a null value. Otherwise generate a warning message and
2975 -- replace Expression (N) by an N_Constraint_Error node.
2977 if K /= N_Function_Specification then
2978 Expr := Expression (N);
2980 if Present (Expr) and then Known_Null (Expr) then
2982 when N_Component_Declaration |
2983 N_Discriminant_Specification =>
2984 Apply_Compile_Time_Constraint_Error
2986 Msg => "(Ada 2005) null not allowed " &
2987 "in null-excluding components?",
2988 Reason => CE_Null_Not_Allowed);
2990 when N_Object_Declaration =>
2991 Apply_Compile_Time_Constraint_Error
2993 Msg => "(Ada 2005) null not allowed " &
2994 "in null-excluding objects?",
2995 Reason => CE_Null_Not_Allowed);
2997 when N_Parameter_Specification =>
2998 Apply_Compile_Time_Constraint_Error
3000 Msg => "(Ada 2005) null not allowed " &
3001 "in null-excluding formals?",
3002 Reason => CE_Null_Not_Allowed);
3009 end Null_Exclusion_Static_Checks;
3011 ----------------------------------
3012 -- Conditional_Statements_Begin --
3013 ----------------------------------
3015 procedure Conditional_Statements_Begin is
3017 Saved_Checks_TOS := Saved_Checks_TOS + 1;
3019 -- If stack overflows, kill all checks, that way we know to simply reset
3020 -- the number of saved checks to zero on return. This should never occur
3023 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
3026 -- In the normal case, we just make a new stack entry saving the current
3027 -- number of saved checks for a later restore.
3030 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
3032 if Debug_Flag_CC then
3033 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
3037 end Conditional_Statements_Begin;
3039 --------------------------------
3040 -- Conditional_Statements_End --
3041 --------------------------------
3043 procedure Conditional_Statements_End is
3045 pragma Assert (Saved_Checks_TOS > 0);
3047 -- If the saved checks stack overflowed, then we killed all checks, so
3048 -- setting the number of saved checks back to zero is correct. This
3049 -- should never occur in practice.
3051 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
3052 Num_Saved_Checks := 0;
3054 -- In the normal case, restore the number of saved checks from the top
3058 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
3059 if Debug_Flag_CC then
3060 w ("Conditional_Statements_End: Num_Saved_Checks = ",
3065 Saved_Checks_TOS := Saved_Checks_TOS - 1;
3066 end Conditional_Statements_End;
3068 ---------------------
3069 -- Determine_Range --
3070 ---------------------
3072 Cache_Size : constant := 2 ** 10;
3073 type Cache_Index is range 0 .. Cache_Size - 1;
3074 -- Determine size of below cache (power of 2 is more efficient!)
3076 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
3077 Determine_Range_Cache_V : array (Cache_Index) of Boolean;
3078 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
3079 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
3080 -- The above arrays are used to implement a small direct cache for
3081 -- Determine_Range calls. Because of the way Determine_Range recursively
3082 -- traces subexpressions, and because overflow checking calls the routine
3083 -- on the way up the tree, a quadratic behavior can otherwise be
3084 -- encountered in large expressions. The cache entry for node N is stored
3085 -- in the (N mod Cache_Size) entry, and can be validated by checking the
3086 -- actual node value stored there. The Range_Cache_V array records the
3087 -- setting of Assume_Valid for the cache entry.
3089 procedure Determine_Range
3094 Assume_Valid : Boolean := False)
3096 Typ : Entity_Id := Etype (N);
3097 -- Type to use, may get reset to base type for possibly invalid entity
3101 -- Lo and Hi bounds of left operand
3105 -- Lo and Hi bounds of right (or only) operand
3108 -- Temp variable used to hold a bound node
3111 -- High bound of base type of expression
3115 -- Refined values for low and high bounds, after tightening
3118 -- Used in lower level calls to indicate if call succeeded
3120 Cindex : Cache_Index;
3121 -- Used to search cache
3123 function OK_Operands return Boolean;
3124 -- Used for binary operators. Determines the ranges of the left and
3125 -- right operands, and if they are both OK, returns True, and puts
3126 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
3132 function OK_Operands return Boolean is
3135 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
3142 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3146 -- Start of processing for Determine_Range
3149 -- For temporary constants internally generated to remove side effects
3150 -- we must use the corresponding expression to determine the range of
3153 if Is_Entity_Name (N)
3154 and then Nkind (Parent (Entity (N))) = N_Object_Declaration
3155 and then Ekind (Entity (N)) = E_Constant
3156 and then Is_Internal_Name (Chars (Entity (N)))
3159 (Expression (Parent (Entity (N))), OK, Lo, Hi, Assume_Valid);
3163 -- Prevent junk warnings by initializing range variables
3170 -- If type is not defined, we can't determine its range
3174 -- We don't deal with anything except discrete types
3176 or else not Is_Discrete_Type (Typ)
3178 -- Ignore type for which an error has been posted, since range in
3179 -- this case may well be a bogosity deriving from the error. Also
3180 -- ignore if error posted on the reference node.
3182 or else Error_Posted (N) or else Error_Posted (Typ)
3188 -- For all other cases, we can determine the range
3192 -- If value is compile time known, then the possible range is the one
3193 -- value that we know this expression definitely has!
3195 if Compile_Time_Known_Value (N) then
3196 Lo := Expr_Value (N);
3201 -- Return if already in the cache
3203 Cindex := Cache_Index (N mod Cache_Size);
3205 if Determine_Range_Cache_N (Cindex) = N
3207 Determine_Range_Cache_V (Cindex) = Assume_Valid
3209 Lo := Determine_Range_Cache_Lo (Cindex);
3210 Hi := Determine_Range_Cache_Hi (Cindex);
3214 -- Otherwise, start by finding the bounds of the type of the expression,
3215 -- the value cannot be outside this range (if it is, then we have an
3216 -- overflow situation, which is a separate check, we are talking here
3217 -- only about the expression value).
3219 -- First a check, never try to find the bounds of a generic type, since
3220 -- these bounds are always junk values, and it is only valid to look at
3221 -- the bounds in an instance.
3223 if Is_Generic_Type (Typ) then
3228 -- First step, change to use base type unless we know the value is valid
3230 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
3231 or else Assume_No_Invalid_Values
3232 or else Assume_Valid
3236 Typ := Underlying_Type (Base_Type (Typ));
3239 -- We use the actual bound unless it is dynamic, in which case use the
3240 -- corresponding base type bound if possible. If we can't get a bound
3241 -- then we figure we can't determine the range (a peculiar case, that
3242 -- perhaps cannot happen, but there is no point in bombing in this
3243 -- optimization circuit.
3245 -- First the low bound
3247 Bound := Type_Low_Bound (Typ);
3249 if Compile_Time_Known_Value (Bound) then
3250 Lo := Expr_Value (Bound);
3252 elsif Compile_Time_Known_Value (Type_Low_Bound (Base_Type (Typ))) then
3253 Lo := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
3260 -- Now the high bound
3262 Bound := Type_High_Bound (Typ);
3264 -- We need the high bound of the base type later on, and this should
3265 -- always be compile time known. Again, it is not clear that this
3266 -- can ever be false, but no point in bombing.
3268 if Compile_Time_Known_Value (Type_High_Bound (Base_Type (Typ))) then
3269 Hbound := Expr_Value (Type_High_Bound (Base_Type (Typ)));
3277 -- If we have a static subtype, then that may have a tighter bound so
3278 -- use the upper bound of the subtype instead in this case.
3280 if Compile_Time_Known_Value (Bound) then
3281 Hi := Expr_Value (Bound);
3284 -- We may be able to refine this value in certain situations. If any
3285 -- refinement is possible, then Lor and Hir are set to possibly tighter
3286 -- bounds, and OK1 is set to True.
3290 -- For unary plus, result is limited by range of operand
3294 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
3296 -- For unary minus, determine range of operand, and negate it
3300 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3307 -- For binary addition, get range of each operand and do the
3308 -- addition to get the result range.
3312 Lor := Lo_Left + Lo_Right;
3313 Hir := Hi_Left + Hi_Right;
3316 -- Division is tricky. The only case we consider is where the right
3317 -- operand is a positive constant, and in this case we simply divide
3318 -- the bounds of the left operand
3322 if Lo_Right = Hi_Right
3323 and then Lo_Right > 0
3325 Lor := Lo_Left / Lo_Right;
3326 Hir := Hi_Left / Lo_Right;
3333 -- For binary subtraction, get range of each operand and do the worst
3334 -- case subtraction to get the result range.
3336 when N_Op_Subtract =>
3338 Lor := Lo_Left - Hi_Right;
3339 Hir := Hi_Left - Lo_Right;
3342 -- For MOD, if right operand is a positive constant, then result must
3343 -- be in the allowable range of mod results.
3347 if Lo_Right = Hi_Right
3348 and then Lo_Right /= 0
3350 if Lo_Right > 0 then
3352 Hir := Lo_Right - 1;
3354 else -- Lo_Right < 0
3355 Lor := Lo_Right + 1;
3364 -- For REM, if right operand is a positive constant, then result must
3365 -- be in the allowable range of mod results.
3369 if Lo_Right = Hi_Right
3370 and then Lo_Right /= 0
3373 Dval : constant Uint := (abs Lo_Right) - 1;
3376 -- The sign of the result depends on the sign of the
3377 -- dividend (but not on the sign of the divisor, hence
3378 -- the abs operation above).
3398 -- Attribute reference cases
3400 when N_Attribute_Reference =>
3401 case Attribute_Name (N) is
3403 -- For Pos/Val attributes, we can refine the range using the
3404 -- possible range of values of the attribute expression.
3406 when Name_Pos | Name_Val =>
3408 (First (Expressions (N)), OK1, Lor, Hir, Assume_Valid);
3410 -- For Length attribute, use the bounds of the corresponding
3411 -- index type to refine the range.
3415 Atyp : Entity_Id := Etype (Prefix (N));
3423 if Is_Access_Type (Atyp) then
3424 Atyp := Designated_Type (Atyp);
3427 -- For string literal, we know exact value
3429 if Ekind (Atyp) = E_String_Literal_Subtype then
3431 Lo := String_Literal_Length (Atyp);
3432 Hi := String_Literal_Length (Atyp);
3436 -- Otherwise check for expression given
3438 if No (Expressions (N)) then
3442 UI_To_Int (Expr_Value (First (Expressions (N))));
3445 Indx := First_Index (Atyp);
3446 for J in 2 .. Inum loop
3447 Indx := Next_Index (Indx);
3450 -- If the index type is a formal type or derived from
3451 -- one, the bounds are not static.
3453 if Is_Generic_Type (Root_Type (Etype (Indx))) then
3459 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU,
3464 (Type_High_Bound (Etype (Indx)), OK1, UL, UU,
3469 -- The maximum value for Length is the biggest
3470 -- possible gap between the values of the bounds.
3471 -- But of course, this value cannot be negative.
3473 Hir := UI_Max (Uint_0, UU - LL + 1);
3475 -- For constrained arrays, the minimum value for
3476 -- Length is taken from the actual value of the
3477 -- bounds, since the index will be exactly of this
3480 if Is_Constrained (Atyp) then
3481 Lor := UI_Max (Uint_0, UL - LU + 1);
3483 -- For an unconstrained array, the minimum value
3484 -- for length is always zero.
3493 -- No special handling for other attributes
3494 -- Probably more opportunities exist here???
3501 -- For type conversion from one discrete type to another, we can
3502 -- refine the range using the converted value.
3504 when N_Type_Conversion =>
3505 Determine_Range (Expression (N), OK1, Lor, Hir, Assume_Valid);
3507 -- Nothing special to do for all other expression kinds
3515 -- At this stage, if OK1 is true, then we know that the actual result of
3516 -- the computed expression is in the range Lor .. Hir. We can use this
3517 -- to restrict the possible range of results.
3519 -- If one of the computed bounds is outside the range of the base type,
3520 -- the expression may raise an exception and we had better indicate that
3521 -- the evaluation has failed, at least if checks are enabled.
3524 and then Enable_Overflow_Checks
3525 and then not Is_Entity_Name (N)
3526 and then (Lor < Lo or else Hir > Hi)
3534 -- If the refined value of the low bound is greater than the type
3535 -- high bound, then reset it to the more restrictive value. However,
3536 -- we do NOT do this for the case of a modular type where the
3537 -- possible upper bound on the value is above the base type high
3538 -- bound, because that means the result could wrap.
3541 and then not (Is_Modular_Integer_Type (Typ) and then Hir > Hbound)
3546 -- Similarly, if the refined value of the high bound is less than the
3547 -- value so far, then reset it to the more restrictive value. Again,
3548 -- we do not do this if the refined low bound is negative for a
3549 -- modular type, since this would wrap.
3552 and then not (Is_Modular_Integer_Type (Typ) and then Lor < Uint_0)
3558 -- Set cache entry for future call and we are all done
3560 Determine_Range_Cache_N (Cindex) := N;
3561 Determine_Range_Cache_V (Cindex) := Assume_Valid;
3562 Determine_Range_Cache_Lo (Cindex) := Lo;
3563 Determine_Range_Cache_Hi (Cindex) := Hi;
3566 -- If any exception occurs, it means that we have some bug in the compiler,
3567 -- possibly triggered by a previous error, or by some unforeseen peculiar
3568 -- occurrence. However, this is only an optimization attempt, so there is
3569 -- really no point in crashing the compiler. Instead we just decide, too
3570 -- bad, we can't figure out a range in this case after all.
3575 -- Debug flag K disables this behavior (useful for debugging)
3577 if Debug_Flag_K then
3585 end Determine_Range;
3587 ------------------------------------
3588 -- Discriminant_Checks_Suppressed --
3589 ------------------------------------
3591 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
3594 if Is_Unchecked_Union (E) then
3596 elsif Checks_May_Be_Suppressed (E) then
3597 return Is_Check_Suppressed (E, Discriminant_Check);
3601 return Scope_Suppress (Discriminant_Check);
3602 end Discriminant_Checks_Suppressed;
3604 --------------------------------
3605 -- Division_Checks_Suppressed --
3606 --------------------------------
3608 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
3610 if Present (E) and then Checks_May_Be_Suppressed (E) then
3611 return Is_Check_Suppressed (E, Division_Check);
3613 return Scope_Suppress (Division_Check);
3615 end Division_Checks_Suppressed;
3617 -----------------------------------
3618 -- Elaboration_Checks_Suppressed --
3619 -----------------------------------
3621 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
3623 -- The complication in this routine is that if we are in the dynamic
3624 -- model of elaboration, we also check All_Checks, since All_Checks
3625 -- does not set Elaboration_Check explicitly.
3628 if Kill_Elaboration_Checks (E) then
3631 elsif Checks_May_Be_Suppressed (E) then
3632 if Is_Check_Suppressed (E, Elaboration_Check) then
3634 elsif Dynamic_Elaboration_Checks then
3635 return Is_Check_Suppressed (E, All_Checks);
3642 if Scope_Suppress (Elaboration_Check) then
3644 elsif Dynamic_Elaboration_Checks then
3645 return Scope_Suppress (All_Checks);
3649 end Elaboration_Checks_Suppressed;
3651 ---------------------------
3652 -- Enable_Overflow_Check --
3653 ---------------------------
3655 procedure Enable_Overflow_Check (N : Node_Id) is
3656 Typ : constant Entity_Id := Base_Type (Etype (N));
3665 if Debug_Flag_CC then
3666 w ("Enable_Overflow_Check for node ", Int (N));
3667 Write_Str (" Source location = ");
3672 -- No check if overflow checks suppressed for type of node
3674 if Present (Etype (N))
3675 and then Overflow_Checks_Suppressed (Etype (N))
3679 -- Nothing to do for unsigned integer types, which do not overflow
3681 elsif Is_Modular_Integer_Type (Typ) then
3684 -- Nothing to do if the range of the result is known OK. We skip this
3685 -- for conversions, since the caller already did the check, and in any
3686 -- case the condition for deleting the check for a type conversion is
3689 elsif Nkind (N) /= N_Type_Conversion then
3690 Determine_Range (N, OK, Lo, Hi, Assume_Valid => True);
3692 -- Note in the test below that we assume that the range is not OK
3693 -- if a bound of the range is equal to that of the type. That's not
3694 -- quite accurate but we do this for the following reasons:
3696 -- a) The way that Determine_Range works, it will typically report
3697 -- the bounds of the value as being equal to the bounds of the
3698 -- type, because it either can't tell anything more precise, or
3699 -- does not think it is worth the effort to be more precise.
3701 -- b) It is very unusual to have a situation in which this would
3702 -- generate an unnecessary overflow check (an example would be
3703 -- a subtype with a range 0 .. Integer'Last - 1 to which the
3704 -- literal value one is added).
3706 -- c) The alternative is a lot of special casing in this routine
3707 -- which would partially duplicate Determine_Range processing.
3710 and then Lo > Expr_Value (Type_Low_Bound (Typ))
3711 and then Hi < Expr_Value (Type_High_Bound (Typ))
3713 if Debug_Flag_CC then
3714 w ("No overflow check required");
3721 -- If not in optimizing mode, set flag and we are done. We are also done
3722 -- (and just set the flag) if the type is not a discrete type, since it
3723 -- is not worth the effort to eliminate checks for other than discrete
3724 -- types. In addition, we take this same path if we have stored the
3725 -- maximum number of checks possible already (a very unlikely situation,
3726 -- but we do not want to blow up!)
3728 if Optimization_Level = 0
3729 or else not Is_Discrete_Type (Etype (N))
3730 or else Num_Saved_Checks = Saved_Checks'Last
3732 Activate_Overflow_Check (N);
3734 if Debug_Flag_CC then
3735 w ("Optimization off");
3741 -- Otherwise evaluate and check the expression
3746 Target_Type => Empty,
3752 if Debug_Flag_CC then
3753 w ("Called Find_Check");
3757 w (" Check_Num = ", Chk);
3758 w (" Ent = ", Int (Ent));
3759 Write_Str (" Ofs = ");
3764 -- If check is not of form to optimize, then set flag and we are done
3767 Activate_Overflow_Check (N);
3771 -- If check is already performed, then return without setting flag
3774 if Debug_Flag_CC then
3775 w ("Check suppressed!");
3781 -- Here we will make a new entry for the new check
3783 Activate_Overflow_Check (N);
3784 Num_Saved_Checks := Num_Saved_Checks + 1;
3785 Saved_Checks (Num_Saved_Checks) :=
3790 Target_Type => Empty);
3792 if Debug_Flag_CC then
3793 w ("Make new entry, check number = ", Num_Saved_Checks);
3794 w (" Entity = ", Int (Ent));
3795 Write_Str (" Offset = ");
3797 w (" Check_Type = O");
3798 w (" Target_Type = Empty");
3801 -- If we get an exception, then something went wrong, probably because of
3802 -- an error in the structure of the tree due to an incorrect program. Or it
3803 -- may be a bug in the optimization circuit. In either case the safest
3804 -- thing is simply to set the check flag unconditionally.
3808 Activate_Overflow_Check (N);
3810 if Debug_Flag_CC then
3811 w (" exception occurred, overflow flag set");
3815 end Enable_Overflow_Check;
3817 ------------------------
3818 -- Enable_Range_Check --
3819 ------------------------
3821 procedure Enable_Range_Check (N : Node_Id) is
3830 -- Return if unchecked type conversion with range check killed. In this
3831 -- case we never set the flag (that's what Kill_Range_Check is about!)
3833 if Nkind (N) = N_Unchecked_Type_Conversion
3834 and then Kill_Range_Check (N)
3839 -- Do not set range check flag if parent is assignment statement or
3840 -- object declaration with Suppress_Assignment_Checks flag set
3842 if Nkind_In (Parent (N), N_Assignment_Statement, N_Object_Declaration)
3843 and then Suppress_Assignment_Checks (Parent (N))
3848 -- Check for various cases where we should suppress the range check
3850 -- No check if range checks suppressed for type of node
3852 if Present (Etype (N))
3853 and then Range_Checks_Suppressed (Etype (N))
3857 -- No check if node is an entity name, and range checks are suppressed
3858 -- for this entity, or for the type of this entity.
3860 elsif Is_Entity_Name (N)
3861 and then (Range_Checks_Suppressed (Entity (N))
3862 or else Range_Checks_Suppressed (Etype (Entity (N))))
3866 -- No checks if index of array, and index checks are suppressed for
3867 -- the array object or the type of the array.
3869 elsif Nkind (Parent (N)) = N_Indexed_Component then
3871 Pref : constant Node_Id := Prefix (Parent (N));
3873 if Is_Entity_Name (Pref)
3874 and then Index_Checks_Suppressed (Entity (Pref))
3877 elsif Index_Checks_Suppressed (Etype (Pref)) then
3883 -- Debug trace output
3885 if Debug_Flag_CC then
3886 w ("Enable_Range_Check for node ", Int (N));
3887 Write_Str (" Source location = ");
3892 -- If not in optimizing mode, set flag and we are done. We are also done
3893 -- (and just set the flag) if the type is not a discrete type, since it
3894 -- is not worth the effort to eliminate checks for other than discrete
3895 -- types. In addition, we take this same path if we have stored the
3896 -- maximum number of checks possible already (a very unlikely situation,
3897 -- but we do not want to blow up!)
3899 if Optimization_Level = 0
3900 or else No (Etype (N))
3901 or else not Is_Discrete_Type (Etype (N))
3902 or else Num_Saved_Checks = Saved_Checks'Last
3904 Activate_Range_Check (N);
3906 if Debug_Flag_CC then
3907 w ("Optimization off");
3913 -- Otherwise find out the target type
3917 -- For assignment, use left side subtype
3919 if Nkind (P) = N_Assignment_Statement
3920 and then Expression (P) = N
3922 Ttyp := Etype (Name (P));
3924 -- For indexed component, use subscript subtype
3926 elsif Nkind (P) = N_Indexed_Component then
3933 Atyp := Etype (Prefix (P));
3935 if Is_Access_Type (Atyp) then
3936 Atyp := Designated_Type (Atyp);
3938 -- If the prefix is an access to an unconstrained array,
3939 -- perform check unconditionally: it depends on the bounds of
3940 -- an object and we cannot currently recognize whether the test
3941 -- may be redundant.
3943 if not Is_Constrained (Atyp) then
3944 Activate_Range_Check (N);
3948 -- Ditto if the prefix is an explicit dereference whose designated
3949 -- type is unconstrained.
3951 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
3952 and then not Is_Constrained (Atyp)
3954 Activate_Range_Check (N);
3958 Indx := First_Index (Atyp);
3959 Subs := First (Expressions (P));
3962 Ttyp := Etype (Indx);
3971 -- For now, ignore all other cases, they are not so interesting
3974 if Debug_Flag_CC then
3975 w (" target type not found, flag set");
3978 Activate_Range_Check (N);
3982 -- Evaluate and check the expression
3987 Target_Type => Ttyp,
3993 if Debug_Flag_CC then
3994 w ("Called Find_Check");
3995 w ("Target_Typ = ", Int (Ttyp));
3999 w (" Check_Num = ", Chk);
4000 w (" Ent = ", Int (Ent));
4001 Write_Str (" Ofs = ");
4006 -- If check is not of form to optimize, then set flag and we are done
4009 if Debug_Flag_CC then
4010 w (" expression not of optimizable type, flag set");
4013 Activate_Range_Check (N);
4017 -- If check is already performed, then return without setting flag
4020 if Debug_Flag_CC then
4021 w ("Check suppressed!");
4027 -- Here we will make a new entry for the new check
4029 Activate_Range_Check (N);
4030 Num_Saved_Checks := Num_Saved_Checks + 1;
4031 Saved_Checks (Num_Saved_Checks) :=
4036 Target_Type => Ttyp);
4038 if Debug_Flag_CC then
4039 w ("Make new entry, check number = ", Num_Saved_Checks);
4040 w (" Entity = ", Int (Ent));
4041 Write_Str (" Offset = ");
4043 w (" Check_Type = R");
4044 w (" Target_Type = ", Int (Ttyp));
4045 pg (Union_Id (Ttyp));
4048 -- If we get an exception, then something went wrong, probably because of
4049 -- an error in the structure of the tree due to an incorrect program. Or
4050 -- it may be a bug in the optimization circuit. In either case the safest
4051 -- thing is simply to set the check flag unconditionally.
4055 Activate_Range_Check (N);
4057 if Debug_Flag_CC then
4058 w (" exception occurred, range flag set");
4062 end Enable_Range_Check;
4068 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
4069 Typ : constant Entity_Id := Etype (Expr);
4072 -- Ignore call if we are not doing any validity checking
4074 if not Validity_Checks_On then
4077 -- Ignore call if range or validity checks suppressed on entity or type
4079 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
4082 -- No check required if expression is from the expander, we assume the
4083 -- expander will generate whatever checks are needed. Note that this is
4084 -- not just an optimization, it avoids infinite recursions!
4086 -- Unchecked conversions must be checked, unless they are initialized
4087 -- scalar values, as in a component assignment in an init proc.
4089 -- In addition, we force a check if Force_Validity_Checks is set
4091 elsif not Comes_From_Source (Expr)
4092 and then not Force_Validity_Checks
4093 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
4094 or else Kill_Range_Check (Expr))
4098 -- No check required if expression is known to have valid value
4100 elsif Expr_Known_Valid (Expr) then
4103 -- Ignore case of enumeration with holes where the flag is set not to
4104 -- worry about holes, since no special validity check is needed
4106 elsif Is_Enumeration_Type (Typ)
4107 and then Has_Non_Standard_Rep (Typ)
4112 -- No check required on the left-hand side of an assignment
4114 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
4115 and then Expr = Name (Parent (Expr))
4119 -- No check on a universal real constant. The context will eventually
4120 -- convert it to a machine number for some target type, or report an
4123 elsif Nkind (Expr) = N_Real_Literal
4124 and then Etype (Expr) = Universal_Real
4128 -- If the expression denotes a component of a packed boolean array,
4129 -- no possible check applies. We ignore the old ACATS chestnuts that
4130 -- involve Boolean range True..True.
4132 -- Note: validity checks are generated for expressions that yield a
4133 -- scalar type, when it is possible to create a value that is outside of
4134 -- the type. If this is a one-bit boolean no such value exists. This is
4135 -- an optimization, and it also prevents compiler blowing up during the
4136 -- elaboration of improperly expanded packed array references.
4138 elsif Nkind (Expr) = N_Indexed_Component
4139 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
4140 and then Root_Type (Etype (Expr)) = Standard_Boolean
4144 -- An annoying special case. If this is an out parameter of a scalar
4145 -- type, then the value is not going to be accessed, therefore it is
4146 -- inappropriate to do any validity check at the call site.
4149 -- Only need to worry about scalar types
4151 if Is_Scalar_Type (Typ) then
4161 -- Find actual argument (which may be a parameter association)
4162 -- and the parent of the actual argument (the call statement)
4167 if Nkind (P) = N_Parameter_Association then
4172 -- Only need to worry if we are argument of a procedure call
4173 -- since functions don't have out parameters. If this is an
4174 -- indirect or dispatching call, get signature from the
4177 if Nkind (P) = N_Procedure_Call_Statement then
4178 L := Parameter_Associations (P);
4180 if Is_Entity_Name (Name (P)) then
4181 E := Entity (Name (P));
4183 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
4184 E := Etype (Name (P));
4187 -- Only need to worry if there are indeed actuals, and if
4188 -- this could be a procedure call, otherwise we cannot get a
4189 -- match (either we are not an argument, or the mode of the
4190 -- formal is not OUT). This test also filters out the
4193 if Is_Non_Empty_List (L)
4194 and then Is_Subprogram (E)
4196 -- This is the loop through parameters, looking for an
4197 -- OUT parameter for which we are the argument.
4199 F := First_Formal (E);
4201 while Present (F) loop
4202 if Ekind (F) = E_Out_Parameter and then A = N then
4215 -- If this is a boolean expression, only its elementary operands need
4216 -- checking: if they are valid, a boolean or short-circuit operation
4217 -- with them will be valid as well.
4219 if Base_Type (Typ) = Standard_Boolean
4221 (Nkind (Expr) in N_Op or else Nkind (Expr) in N_Short_Circuit)
4226 -- If we fall through, a validity check is required
4228 Insert_Valid_Check (Expr);
4230 if Is_Entity_Name (Expr)
4231 and then Safe_To_Capture_Value (Expr, Entity (Expr))
4233 Set_Is_Known_Valid (Entity (Expr));
4237 ----------------------
4238 -- Expr_Known_Valid --
4239 ----------------------
4241 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
4242 Typ : constant Entity_Id := Etype (Expr);
4245 -- Non-scalar types are always considered valid, since they never give
4246 -- rise to the issues of erroneous or bounded error behavior that are
4247 -- the concern. In formal reference manual terms the notion of validity
4248 -- only applies to scalar types. Note that even when packed arrays are
4249 -- represented using modular types, they are still arrays semantically,
4250 -- so they are also always valid (in particular, the unused bits can be
4251 -- random rubbish without affecting the validity of the array value).
4253 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
4256 -- If no validity checking, then everything is considered valid
4258 elsif not Validity_Checks_On then
4261 -- Floating-point types are considered valid unless floating-point
4262 -- validity checks have been specifically turned on.
4264 elsif Is_Floating_Point_Type (Typ)
4265 and then not Validity_Check_Floating_Point
4269 -- If the expression is the value of an object that is known to be
4270 -- valid, then clearly the expression value itself is valid.
4272 elsif Is_Entity_Name (Expr)
4273 and then Is_Known_Valid (Entity (Expr))
4277 -- References to discriminants are always considered valid. The value
4278 -- of a discriminant gets checked when the object is built. Within the
4279 -- record, we consider it valid, and it is important to do so, since
4280 -- otherwise we can try to generate bogus validity checks which
4281 -- reference discriminants out of scope. Discriminants of concurrent
4282 -- types are excluded for the same reason.
4284 elsif Is_Entity_Name (Expr)
4285 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
4289 -- If the type is one for which all values are known valid, then we are
4290 -- sure that the value is valid except in the slightly odd case where
4291 -- the expression is a reference to a variable whose size has been
4292 -- explicitly set to a value greater than the object size.
4294 elsif Is_Known_Valid (Typ) then
4295 if Is_Entity_Name (Expr)
4296 and then Ekind (Entity (Expr)) = E_Variable
4297 and then Esize (Entity (Expr)) > Esize (Typ)
4304 -- Integer and character literals always have valid values, where
4305 -- appropriate these will be range checked in any case.
4307 elsif Nkind (Expr) = N_Integer_Literal
4309 Nkind (Expr) = N_Character_Literal
4313 -- If we have a type conversion or a qualification of a known valid
4314 -- value, then the result will always be valid.
4316 elsif Nkind (Expr) = N_Type_Conversion
4318 Nkind (Expr) = N_Qualified_Expression
4320 return Expr_Known_Valid (Expression (Expr));
4322 -- The result of any operator is always considered valid, since we
4323 -- assume the necessary checks are done by the operator. For operators
4324 -- on floating-point operations, we must also check when the operation
4325 -- is the right-hand side of an assignment, or is an actual in a call.
4327 elsif Nkind (Expr) in N_Op then
4328 if Is_Floating_Point_Type (Typ)
4329 and then Validity_Check_Floating_Point
4331 (Nkind (Parent (Expr)) = N_Assignment_Statement
4332 or else Nkind (Parent (Expr)) = N_Function_Call
4333 or else Nkind (Parent (Expr)) = N_Parameter_Association)
4340 -- The result of a membership test is always valid, since it is true or
4341 -- false, there are no other possibilities.
4343 elsif Nkind (Expr) in N_Membership_Test then
4346 -- For all other cases, we do not know the expression is valid
4351 end Expr_Known_Valid;
4357 procedure Find_Check
4359 Check_Type : Character;
4360 Target_Type : Entity_Id;
4361 Entry_OK : out Boolean;
4362 Check_Num : out Nat;
4363 Ent : out Entity_Id;
4366 function Within_Range_Of
4367 (Target_Type : Entity_Id;
4368 Check_Type : Entity_Id) return Boolean;
4369 -- Given a requirement for checking a range against Target_Type, and
4370 -- and a range Check_Type against which a check has already been made,
4371 -- determines if the check against check type is sufficient to ensure
4372 -- that no check against Target_Type is required.
4374 ---------------------
4375 -- Within_Range_Of --
4376 ---------------------
4378 function Within_Range_Of
4379 (Target_Type : Entity_Id;
4380 Check_Type : Entity_Id) return Boolean
4383 if Target_Type = Check_Type then
4388 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
4389 Thi : constant Node_Id := Type_High_Bound (Target_Type);
4390 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
4391 Chi : constant Node_Id := Type_High_Bound (Check_Type);
4395 or else (Compile_Time_Known_Value (Tlo)
4397 Compile_Time_Known_Value (Clo)
4399 Expr_Value (Clo) >= Expr_Value (Tlo)))
4402 or else (Compile_Time_Known_Value (Thi)
4404 Compile_Time_Known_Value (Chi)
4406 Expr_Value (Chi) <= Expr_Value (Clo)))
4414 end Within_Range_Of;
4416 -- Start of processing for Find_Check
4419 -- Establish default, in case no entry is found
4423 -- Case of expression is simple entity reference
4425 if Is_Entity_Name (Expr) then
4426 Ent := Entity (Expr);
4429 -- Case of expression is entity + known constant
4431 elsif Nkind (Expr) = N_Op_Add
4432 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4433 and then Is_Entity_Name (Left_Opnd (Expr))
4435 Ent := Entity (Left_Opnd (Expr));
4436 Ofs := Expr_Value (Right_Opnd (Expr));
4438 -- Case of expression is entity - known constant
4440 elsif Nkind (Expr) = N_Op_Subtract
4441 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4442 and then Is_Entity_Name (Left_Opnd (Expr))
4444 Ent := Entity (Left_Opnd (Expr));
4445 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
4447 -- Any other expression is not of the right form
4456 -- Come here with expression of appropriate form, check if entity is an
4457 -- appropriate one for our purposes.
4459 if (Ekind (Ent) = E_Variable
4460 or else Is_Constant_Object (Ent))
4461 and then not Is_Library_Level_Entity (Ent)
4469 -- See if there is matching check already
4471 for J in reverse 1 .. Num_Saved_Checks loop
4473 SC : Saved_Check renames Saved_Checks (J);
4476 if SC.Killed = False
4477 and then SC.Entity = Ent
4478 and then SC.Offset = Ofs
4479 and then SC.Check_Type = Check_Type
4480 and then Within_Range_Of (Target_Type, SC.Target_Type)
4488 -- If we fall through entry was not found
4493 ---------------------------------
4494 -- Generate_Discriminant_Check --
4495 ---------------------------------
4497 -- Note: the code for this procedure is derived from the
4498 -- Emit_Discriminant_Check Routine in trans.c.
4500 procedure Generate_Discriminant_Check (N : Node_Id) is
4501 Loc : constant Source_Ptr := Sloc (N);
4502 Pref : constant Node_Id := Prefix (N);
4503 Sel : constant Node_Id := Selector_Name (N);
4505 Orig_Comp : constant Entity_Id :=
4506 Original_Record_Component (Entity (Sel));
4507 -- The original component to be checked
4509 Discr_Fct : constant Entity_Id :=
4510 Discriminant_Checking_Func (Orig_Comp);
4511 -- The discriminant checking function
4514 -- One discriminant to be checked in the type
4516 Real_Discr : Entity_Id;
4517 -- Actual discriminant in the call
4519 Pref_Type : Entity_Id;
4520 -- Type of relevant prefix (ignoring private/access stuff)
4523 -- List of arguments for function call
4526 -- Keep track of the formal corresponding to the actual we build for
4527 -- each discriminant, in order to be able to perform the necessary type
4531 -- Selected component reference for checking function argument
4534 Pref_Type := Etype (Pref);
4536 -- Force evaluation of the prefix, so that it does not get evaluated
4537 -- twice (once for the check, once for the actual reference). Such a
4538 -- double evaluation is always a potential source of inefficiency,
4539 -- and is functionally incorrect in the volatile case, or when the
4540 -- prefix may have side-effects. An entity or a component of an
4541 -- entity requires no evaluation.
4543 if Is_Entity_Name (Pref) then
4544 if Treat_As_Volatile (Entity (Pref)) then
4545 Force_Evaluation (Pref, Name_Req => True);
4548 elsif Treat_As_Volatile (Etype (Pref)) then
4549 Force_Evaluation (Pref, Name_Req => True);
4551 elsif Nkind (Pref) = N_Selected_Component
4552 and then Is_Entity_Name (Prefix (Pref))
4557 Force_Evaluation (Pref, Name_Req => True);
4560 -- For a tagged type, use the scope of the original component to
4561 -- obtain the type, because ???
4563 if Is_Tagged_Type (Scope (Orig_Comp)) then
4564 Pref_Type := Scope (Orig_Comp);
4566 -- For an untagged derived type, use the discriminants of the parent
4567 -- which have been renamed in the derivation, possibly by a one-to-many
4568 -- discriminant constraint. For non-tagged type, initially get the Etype
4572 if Is_Derived_Type (Pref_Type)
4573 and then Number_Discriminants (Pref_Type) /=
4574 Number_Discriminants (Etype (Base_Type (Pref_Type)))
4576 Pref_Type := Etype (Base_Type (Pref_Type));
4580 -- We definitely should have a checking function, This routine should
4581 -- not be called if no discriminant checking function is present.
4583 pragma Assert (Present (Discr_Fct));
4585 -- Create the list of the actual parameters for the call. This list
4586 -- is the list of the discriminant fields of the record expression to
4587 -- be discriminant checked.
4590 Formal := First_Formal (Discr_Fct);
4591 Discr := First_Discriminant (Pref_Type);
4592 while Present (Discr) loop
4594 -- If we have a corresponding discriminant field, and a parent
4595 -- subtype is present, then we want to use the corresponding
4596 -- discriminant since this is the one with the useful value.
4598 if Present (Corresponding_Discriminant (Discr))
4599 and then Ekind (Pref_Type) = E_Record_Type
4600 and then Present (Parent_Subtype (Pref_Type))
4602 Real_Discr := Corresponding_Discriminant (Discr);
4604 Real_Discr := Discr;
4607 -- Construct the reference to the discriminant
4610 Make_Selected_Component (Loc,
4612 Unchecked_Convert_To (Pref_Type,
4613 Duplicate_Subexpr (Pref)),
4614 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
4616 -- Manually analyze and resolve this selected component. We really
4617 -- want it just as it appears above, and do not want the expander
4618 -- playing discriminal games etc with this reference. Then we append
4619 -- the argument to the list we are gathering.
4621 Set_Etype (Scomp, Etype (Real_Discr));
4622 Set_Analyzed (Scomp, True);
4623 Append_To (Args, Convert_To (Etype (Formal), Scomp));
4625 Next_Formal_With_Extras (Formal);
4626 Next_Discriminant (Discr);
4629 -- Now build and insert the call
4632 Make_Raise_Constraint_Error (Loc,
4634 Make_Function_Call (Loc,
4635 Name => New_Occurrence_Of (Discr_Fct, Loc),
4636 Parameter_Associations => Args),
4637 Reason => CE_Discriminant_Check_Failed));
4638 end Generate_Discriminant_Check;
4640 ---------------------------
4641 -- Generate_Index_Checks --
4642 ---------------------------
4644 procedure Generate_Index_Checks (N : Node_Id) is
4646 function Entity_Of_Prefix return Entity_Id;
4647 -- Returns the entity of the prefix of N (or Empty if not found)
4649 ----------------------
4650 -- Entity_Of_Prefix --
4651 ----------------------
4653 function Entity_Of_Prefix return Entity_Id is
4658 while not Is_Entity_Name (P) loop
4659 if not Nkind_In (P, N_Selected_Component,
4660 N_Indexed_Component)
4669 end Entity_Of_Prefix;
4673 Loc : constant Source_Ptr := Sloc (N);
4674 A : constant Node_Id := Prefix (N);
4675 A_Ent : constant Entity_Id := Entity_Of_Prefix;
4678 -- Start of processing for Generate_Index_Checks
4681 -- Ignore call if the prefix is not an array since we have a serious
4682 -- error in the sources. Ignore it also if index checks are suppressed
4683 -- for array object or type.
4685 if not Is_Array_Type (Etype (A))
4686 or else (Present (A_Ent)
4687 and then Index_Checks_Suppressed (A_Ent))
4688 or else Index_Checks_Suppressed (Etype (A))
4693 -- Generate a raise of constraint error with the appropriate reason and
4694 -- a condition of the form:
4696 -- Base_Type (Sub) not in Array'Range (Subscript)
4698 -- Note that the reason we generate the conversion to the base type here
4699 -- is that we definitely want the range check to take place, even if it
4700 -- looks like the subtype is OK. Optimization considerations that allow
4701 -- us to omit the check have already been taken into account in the
4702 -- setting of the Do_Range_Check flag earlier on.
4704 Sub := First (Expressions (N));
4706 -- Handle string literals
4708 if Ekind (Etype (A)) = E_String_Literal_Subtype then
4709 if Do_Range_Check (Sub) then
4710 Set_Do_Range_Check (Sub, False);
4712 -- For string literals we obtain the bounds of the string from the
4713 -- associated subtype.
4716 Make_Raise_Constraint_Error (Loc,
4720 Convert_To (Base_Type (Etype (Sub)),
4721 Duplicate_Subexpr_Move_Checks (Sub)),
4723 Make_Attribute_Reference (Loc,
4724 Prefix => New_Reference_To (Etype (A), Loc),
4725 Attribute_Name => Name_Range)),
4726 Reason => CE_Index_Check_Failed));
4733 A_Idx : Node_Id := Empty;
4740 A_Idx := First_Index (Etype (A));
4742 while Present (Sub) loop
4743 if Do_Range_Check (Sub) then
4744 Set_Do_Range_Check (Sub, False);
4746 -- Force evaluation except for the case of a simple name of
4747 -- a non-volatile entity.
4749 if not Is_Entity_Name (Sub)
4750 or else Treat_As_Volatile (Entity (Sub))
4752 Force_Evaluation (Sub);
4755 if Nkind (A_Idx) = N_Range then
4758 elsif Nkind (A_Idx) = N_Identifier
4759 or else Nkind (A_Idx) = N_Expanded_Name
4761 A_Range := Scalar_Range (Entity (A_Idx));
4763 else pragma Assert (Nkind (A_Idx) = N_Subtype_Indication);
4764 A_Range := Range_Expression (Constraint (A_Idx));
4767 -- For array objects with constant bounds we can generate
4768 -- the index check using the bounds of the type of the index
4771 and then Ekind (A_Ent) = E_Variable
4772 and then Is_Constant_Bound (Low_Bound (A_Range))
4773 and then Is_Constant_Bound (High_Bound (A_Range))
4776 Make_Attribute_Reference (Loc,
4778 New_Reference_To (Etype (A_Idx), Loc),
4779 Attribute_Name => Name_Range);
4781 -- For arrays with non-constant bounds we cannot generate
4782 -- the index check using the bounds of the type of the index
4783 -- since it may reference discriminants of some enclosing
4784 -- type. We obtain the bounds directly from the prefix
4791 Num := New_List (Make_Integer_Literal (Loc, Ind));
4795 Make_Attribute_Reference (Loc,
4797 Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
4798 Attribute_Name => Name_Range,
4799 Expressions => Num);
4803 Make_Raise_Constraint_Error (Loc,
4807 Convert_To (Base_Type (Etype (Sub)),
4808 Duplicate_Subexpr_Move_Checks (Sub)),
4809 Right_Opnd => Range_N),
4810 Reason => CE_Index_Check_Failed));
4813 A_Idx := Next_Index (A_Idx);
4819 end Generate_Index_Checks;
4821 --------------------------
4822 -- Generate_Range_Check --
4823 --------------------------
4825 procedure Generate_Range_Check
4827 Target_Type : Entity_Id;
4828 Reason : RT_Exception_Code)
4830 Loc : constant Source_Ptr := Sloc (N);
4831 Source_Type : constant Entity_Id := Etype (N);
4832 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
4833 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
4836 -- First special case, if the source type is already within the range
4837 -- of the target type, then no check is needed (probably we should have
4838 -- stopped Do_Range_Check from being set in the first place, but better
4839 -- late than later in preventing junk code!
4841 -- We do NOT apply this if the source node is a literal, since in this
4842 -- case the literal has already been labeled as having the subtype of
4845 if In_Subrange_Of (Source_Type, Target_Type)
4847 (Nkind (N) = N_Integer_Literal
4849 Nkind (N) = N_Real_Literal
4851 Nkind (N) = N_Character_Literal
4854 and then Ekind (Entity (N)) = E_Enumeration_Literal))
4859 -- We need a check, so force evaluation of the node, so that it does
4860 -- not get evaluated twice (once for the check, once for the actual
4861 -- reference). Such a double evaluation is always a potential source
4862 -- of inefficiency, and is functionally incorrect in the volatile case.
4864 if not Is_Entity_Name (N)
4865 or else Treat_As_Volatile (Entity (N))
4867 Force_Evaluation (N);
4870 -- The easiest case is when Source_Base_Type and Target_Base_Type are
4871 -- the same since in this case we can simply do a direct check of the
4872 -- value of N against the bounds of Target_Type.
4874 -- [constraint_error when N not in Target_Type]
4876 -- Note: this is by far the most common case, for example all cases of
4877 -- checks on the RHS of assignments are in this category, but not all
4878 -- cases are like this. Notably conversions can involve two types.
4880 if Source_Base_Type = Target_Base_Type then
4882 Make_Raise_Constraint_Error (Loc,
4885 Left_Opnd => Duplicate_Subexpr (N),
4886 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4889 -- Next test for the case where the target type is within the bounds
4890 -- of the base type of the source type, since in this case we can
4891 -- simply convert these bounds to the base type of T to do the test.
4893 -- [constraint_error when N not in
4894 -- Source_Base_Type (Target_Type'First)
4896 -- Source_Base_Type(Target_Type'Last))]
4898 -- The conversions will always work and need no check
4900 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
4901 -- of converting from an enumeration value to an integer type, such as
4902 -- occurs for the case of generating a range check on Enum'Val(Exp)
4903 -- (which used to be handled by gigi). This is OK, since the conversion
4904 -- itself does not require a check.
4906 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
4908 Make_Raise_Constraint_Error (Loc,
4911 Left_Opnd => Duplicate_Subexpr (N),
4916 Unchecked_Convert_To (Source_Base_Type,
4917 Make_Attribute_Reference (Loc,
4919 New_Occurrence_Of (Target_Type, Loc),
4920 Attribute_Name => Name_First)),
4923 Unchecked_Convert_To (Source_Base_Type,
4924 Make_Attribute_Reference (Loc,
4926 New_Occurrence_Of (Target_Type, Loc),
4927 Attribute_Name => Name_Last)))),
4930 -- Note that at this stage we now that the Target_Base_Type is not in
4931 -- the range of the Source_Base_Type (since even the Target_Type itself
4932 -- is not in this range). It could still be the case that Source_Type is
4933 -- in range of the target base type since we have not checked that case.
4935 -- If that is the case, we can freely convert the source to the target,
4936 -- and then test the target result against the bounds.
4938 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
4940 -- We make a temporary to hold the value of the converted value
4941 -- (converted to the base type), and then we will do the test against
4944 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
4945 -- [constraint_error when Tnn not in Target_Type]
4947 -- Then the conversion itself is replaced by an occurrence of Tnn
4950 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
4953 Insert_Actions (N, New_List (
4954 Make_Object_Declaration (Loc,
4955 Defining_Identifier => Tnn,
4956 Object_Definition =>
4957 New_Occurrence_Of (Target_Base_Type, Loc),
4958 Constant_Present => True,
4960 Make_Type_Conversion (Loc,
4961 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
4962 Expression => Duplicate_Subexpr (N))),
4964 Make_Raise_Constraint_Error (Loc,
4967 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4968 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4970 Reason => Reason)));
4972 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4974 -- Set the type of N, because the declaration for Tnn might not
4975 -- be analyzed yet, as is the case if N appears within a record
4976 -- declaration, as a discriminant constraint or expression.
4978 Set_Etype (N, Target_Base_Type);
4981 -- At this stage, we know that we have two scalar types, which are
4982 -- directly convertible, and where neither scalar type has a base
4983 -- range that is in the range of the other scalar type.
4985 -- The only way this can happen is with a signed and unsigned type.
4986 -- So test for these two cases:
4989 -- Case of the source is unsigned and the target is signed
4991 if Is_Unsigned_Type (Source_Base_Type)
4992 and then not Is_Unsigned_Type (Target_Base_Type)
4994 -- If the source is unsigned and the target is signed, then we
4995 -- know that the source is not shorter than the target (otherwise
4996 -- the source base type would be in the target base type range).
4998 -- In other words, the unsigned type is either the same size as
4999 -- the target, or it is larger. It cannot be smaller.
5002 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
5004 -- We only need to check the low bound if the low bound of the
5005 -- target type is non-negative. If the low bound of the target
5006 -- type is negative, then we know that we will fit fine.
5008 -- If the high bound of the target type is negative, then we
5009 -- know we have a constraint error, since we can't possibly
5010 -- have a negative source.
5012 -- With these two checks out of the way, we can do the check
5013 -- using the source type safely
5015 -- This is definitely the most annoying case!
5017 -- [constraint_error
5018 -- when (Target_Type'First >= 0
5020 -- N < Source_Base_Type (Target_Type'First))
5021 -- or else Target_Type'Last < 0
5022 -- or else N > Source_Base_Type (Target_Type'Last)];
5024 -- We turn off all checks since we know that the conversions
5025 -- will work fine, given the guards for negative values.
5028 Make_Raise_Constraint_Error (Loc,
5034 Left_Opnd => Make_Op_Ge (Loc,
5036 Make_Attribute_Reference (Loc,
5038 New_Occurrence_Of (Target_Type, Loc),
5039 Attribute_Name => Name_First),
5040 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
5044 Left_Opnd => Duplicate_Subexpr (N),
5046 Convert_To (Source_Base_Type,
5047 Make_Attribute_Reference (Loc,
5049 New_Occurrence_Of (Target_Type, Loc),
5050 Attribute_Name => Name_First)))),
5055 Make_Attribute_Reference (Loc,
5056 Prefix => New_Occurrence_Of (Target_Type, Loc),
5057 Attribute_Name => Name_Last),
5058 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
5062 Left_Opnd => Duplicate_Subexpr (N),
5064 Convert_To (Source_Base_Type,
5065 Make_Attribute_Reference (Loc,
5066 Prefix => New_Occurrence_Of (Target_Type, Loc),
5067 Attribute_Name => Name_Last)))),
5070 Suppress => All_Checks);
5072 -- Only remaining possibility is that the source is signed and
5073 -- the target is unsigned.
5076 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
5077 and then Is_Unsigned_Type (Target_Base_Type));
5079 -- If the source is signed and the target is unsigned, then we
5080 -- know that the target is not shorter than the source (otherwise
5081 -- the target base type would be in the source base type range).
5083 -- In other words, the unsigned type is either the same size as
5084 -- the target, or it is larger. It cannot be smaller.
5086 -- Clearly we have an error if the source value is negative since
5087 -- no unsigned type can have negative values. If the source type
5088 -- is non-negative, then the check can be done using the target
5091 -- Tnn : constant Target_Base_Type (N) := Target_Type;
5093 -- [constraint_error
5094 -- when N < 0 or else Tnn not in Target_Type];
5096 -- We turn off all checks for the conversion of N to the target
5097 -- base type, since we generate the explicit check to ensure that
5098 -- the value is non-negative
5101 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
5104 Insert_Actions (N, New_List (
5105 Make_Object_Declaration (Loc,
5106 Defining_Identifier => Tnn,
5107 Object_Definition =>
5108 New_Occurrence_Of (Target_Base_Type, Loc),
5109 Constant_Present => True,
5111 Make_Unchecked_Type_Conversion (Loc,
5113 New_Occurrence_Of (Target_Base_Type, Loc),
5114 Expression => Duplicate_Subexpr (N))),
5116 Make_Raise_Constraint_Error (Loc,
5121 Left_Opnd => Duplicate_Subexpr (N),
5122 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
5126 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
5128 New_Occurrence_Of (Target_Type, Loc))),
5131 Suppress => All_Checks);
5133 -- Set the Etype explicitly, because Insert_Actions may have
5134 -- placed the declaration in the freeze list for an enclosing
5135 -- construct, and thus it is not analyzed yet.
5137 Set_Etype (Tnn, Target_Base_Type);
5138 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
5142 end Generate_Range_Check;
5148 function Get_Check_Id (N : Name_Id) return Check_Id is
5150 -- For standard check name, we can do a direct computation
5152 if N in First_Check_Name .. Last_Check_Name then
5153 return Check_Id (N - (First_Check_Name - 1));
5155 -- For non-standard names added by pragma Check_Name, search table
5158 for J in All_Checks + 1 .. Check_Names.Last loop
5159 if Check_Names.Table (J) = N then
5165 -- No matching name found
5170 ---------------------
5171 -- Get_Discriminal --
5172 ---------------------
5174 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
5175 Loc : constant Source_Ptr := Sloc (E);
5180 -- The bound can be a bona fide parameter of a protected operation,
5181 -- rather than a prival encoded as an in-parameter.
5183 if No (Discriminal_Link (Entity (Bound))) then
5187 -- Climb the scope stack looking for an enclosing protected type. If
5188 -- we run out of scopes, return the bound itself.
5191 while Present (Sc) loop
5192 if Sc = Standard_Standard then
5195 elsif Ekind (Sc) = E_Protected_Type then
5202 D := First_Discriminant (Sc);
5203 while Present (D) loop
5204 if Chars (D) = Chars (Bound) then
5205 return New_Occurrence_Of (Discriminal (D), Loc);
5208 Next_Discriminant (D);
5212 end Get_Discriminal;
5214 ----------------------
5215 -- Get_Range_Checks --
5216 ----------------------
5218 function Get_Range_Checks
5220 Target_Typ : Entity_Id;
5221 Source_Typ : Entity_Id := Empty;
5222 Warn_Node : Node_Id := Empty) return Check_Result
5225 return Selected_Range_Checks
5226 (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
5227 end Get_Range_Checks;
5233 function Guard_Access
5236 Ck_Node : Node_Id) return Node_Id
5239 if Nkind (Cond) = N_Or_Else then
5240 Set_Paren_Count (Cond, 1);
5243 if Nkind (Ck_Node) = N_Allocator then
5250 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
5251 Right_Opnd => Make_Null (Loc)),
5252 Right_Opnd => Cond);
5256 -----------------------------
5257 -- Index_Checks_Suppressed --
5258 -----------------------------
5260 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
5262 if Present (E) and then Checks_May_Be_Suppressed (E) then
5263 return Is_Check_Suppressed (E, Index_Check);
5265 return Scope_Suppress (Index_Check);
5267 end Index_Checks_Suppressed;
5273 procedure Initialize is
5275 for J in Determine_Range_Cache_N'Range loop
5276 Determine_Range_Cache_N (J) := Empty;
5281 for J in Int range 1 .. All_Checks loop
5282 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
5286 -------------------------
5287 -- Insert_Range_Checks --
5288 -------------------------
5290 procedure Insert_Range_Checks
5291 (Checks : Check_Result;
5293 Suppress_Typ : Entity_Id;
5294 Static_Sloc : Source_Ptr := No_Location;
5295 Flag_Node : Node_Id := Empty;
5296 Do_Before : Boolean := False)
5298 Internal_Flag_Node : Node_Id := Flag_Node;
5299 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
5301 Check_Node : Node_Id;
5302 Checks_On : constant Boolean :=
5303 (not Index_Checks_Suppressed (Suppress_Typ))
5305 (not Range_Checks_Suppressed (Suppress_Typ));
5308 -- For now we just return if Checks_On is false, however this should be
5309 -- enhanced to check for an always True value in the condition and to
5310 -- generate a compilation warning???
5312 if not Full_Expander_Active or else not Checks_On then
5316 if Static_Sloc = No_Location then
5317 Internal_Static_Sloc := Sloc (Node);
5320 if No (Flag_Node) then
5321 Internal_Flag_Node := Node;
5324 for J in 1 .. 2 loop
5325 exit when No (Checks (J));
5327 if Nkind (Checks (J)) = N_Raise_Constraint_Error
5328 and then Present (Condition (Checks (J)))
5330 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
5331 Check_Node := Checks (J);
5332 Mark_Rewrite_Insertion (Check_Node);
5335 Insert_Before_And_Analyze (Node, Check_Node);
5337 Insert_After_And_Analyze (Node, Check_Node);
5340 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
5345 Make_Raise_Constraint_Error (Internal_Static_Sloc,
5346 Reason => CE_Range_Check_Failed);
5347 Mark_Rewrite_Insertion (Check_Node);
5350 Insert_Before_And_Analyze (Node, Check_Node);
5352 Insert_After_And_Analyze (Node, Check_Node);
5356 end Insert_Range_Checks;
5358 ------------------------
5359 -- Insert_Valid_Check --
5360 ------------------------
5362 procedure Insert_Valid_Check (Expr : Node_Id) is
5363 Loc : constant Source_Ptr := Sloc (Expr);
5367 -- Do not insert if checks off, or if not checking validity or
5368 -- if expression is known to be valid
5370 if not Validity_Checks_On
5371 or else Range_Or_Validity_Checks_Suppressed (Expr)
5372 or else Expr_Known_Valid (Expr)
5377 -- If we have a checked conversion, then validity check applies to
5378 -- the expression inside the conversion, not the result, since if
5379 -- the expression inside is valid, then so is the conversion result.
5382 while Nkind (Exp) = N_Type_Conversion loop
5383 Exp := Expression (Exp);
5386 -- We are about to insert the validity check for Exp. We save and
5387 -- reset the Do_Range_Check flag over this validity check, and then
5388 -- put it back for the final original reference (Exp may be rewritten).
5391 DRC : constant Boolean := Do_Range_Check (Exp);
5394 Set_Do_Range_Check (Exp, False);
5396 -- Force evaluation to avoid multiple reads for atomic/volatile
5398 if Is_Entity_Name (Exp)
5399 and then Is_Volatile (Entity (Exp))
5401 Force_Evaluation (Exp, Name_Req => True);
5404 -- Insert the validity check. Note that we do this with validity
5405 -- checks turned off, to avoid recursion, we do not want validity
5406 -- checks on the validity checking code itself!
5410 Make_Raise_Constraint_Error (Loc,
5414 Make_Attribute_Reference (Loc,
5416 Duplicate_Subexpr_No_Checks (Exp, Name_Req => True),
5417 Attribute_Name => Name_Valid)),
5418 Reason => CE_Invalid_Data),
5419 Suppress => Validity_Check);
5421 -- If the expression is a reference to an element of a bit-packed
5422 -- array, then it is rewritten as a renaming declaration. If the
5423 -- expression is an actual in a call, it has not been expanded,
5424 -- waiting for the proper point at which to do it. The same happens
5425 -- with renamings, so that we have to force the expansion now. This
5426 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
5429 if Is_Entity_Name (Exp)
5430 and then Nkind (Parent (Entity (Exp))) =
5431 N_Object_Renaming_Declaration
5434 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
5436 if Nkind (Old_Exp) = N_Indexed_Component
5437 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
5439 Expand_Packed_Element_Reference (Old_Exp);
5444 -- Put back the Do_Range_Check flag on the resulting (possibly
5445 -- rewritten) expression.
5447 -- Note: it might be thought that a validity check is not required
5448 -- when a range check is present, but that's not the case, because
5449 -- the back end is allowed to assume for the range check that the
5450 -- operand is within its declared range (an assumption that validity
5451 -- checking is all about NOT assuming!)
5453 -- Note: no need to worry about Possible_Local_Raise here, it will
5454 -- already have been called if original node has Do_Range_Check set.
5456 Set_Do_Range_Check (Exp, DRC);
5458 end Insert_Valid_Check;
5460 ----------------------------------
5461 -- Install_Null_Excluding_Check --
5462 ----------------------------------
5464 procedure Install_Null_Excluding_Check (N : Node_Id) is
5465 Loc : constant Source_Ptr := Sloc (Parent (N));
5466 Typ : constant Entity_Id := Etype (N);
5468 function Safe_To_Capture_In_Parameter_Value return Boolean;
5469 -- Determines if it is safe to capture Known_Non_Null status for an
5470 -- the entity referenced by node N. The caller ensures that N is indeed
5471 -- an entity name. It is safe to capture the non-null status for an IN
5472 -- parameter when the reference occurs within a declaration that is sure
5473 -- to be executed as part of the declarative region.
5475 procedure Mark_Non_Null;
5476 -- After installation of check, if the node in question is an entity
5477 -- name, then mark this entity as non-null if possible.
5479 function Safe_To_Capture_In_Parameter_Value return Boolean is
5480 E : constant Entity_Id := Entity (N);
5481 S : constant Entity_Id := Current_Scope;
5485 if Ekind (E) /= E_In_Parameter then
5489 -- Two initial context checks. We must be inside a subprogram body
5490 -- with declarations and reference must not appear in nested scopes.
5492 if (Ekind (S) /= E_Function and then Ekind (S) /= E_Procedure)
5493 or else Scope (E) /= S
5498 S_Par := Parent (Parent (S));
5500 if Nkind (S_Par) /= N_Subprogram_Body
5501 or else No (Declarations (S_Par))
5511 -- Retrieve the declaration node of N (if any). Note that N
5512 -- may be a part of a complex initialization expression.
5516 while Present (P) loop
5518 -- If we have a short circuit form, and we are within the right
5519 -- hand expression, we return false, since the right hand side
5520 -- is not guaranteed to be elaborated.
5522 if Nkind (P) in N_Short_Circuit
5523 and then N = Right_Opnd (P)
5528 -- Similarly, if we are in a conditional expression and not
5529 -- part of the condition, then we return False, since neither
5530 -- the THEN or ELSE expressions will always be elaborated.
5532 if Nkind (P) = N_Conditional_Expression
5533 and then N /= First (Expressions (P))
5538 -- If we are in a case expression, and not part of the
5539 -- expression, then we return False, since a particular
5540 -- branch may not always be elaborated
5542 if Nkind (P) = N_Case_Expression
5543 and then N /= Expression (P)
5548 -- While traversing the parent chain, we find that N
5549 -- belongs to a statement, thus it may never appear in
5550 -- a declarative region.
5552 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
5553 or else Nkind (P) = N_Procedure_Call_Statement
5558 -- If we are at a declaration, record it and exit
5560 if Nkind (P) in N_Declaration
5561 and then Nkind (P) not in N_Subprogram_Specification
5574 return List_Containing (N_Decl) = Declarations (S_Par);
5576 end Safe_To_Capture_In_Parameter_Value;
5582 procedure Mark_Non_Null is
5584 -- Only case of interest is if node N is an entity name
5586 if Is_Entity_Name (N) then
5588 -- For sure, we want to clear an indication that this is known to
5589 -- be null, since if we get past this check, it definitely is not!
5591 Set_Is_Known_Null (Entity (N), False);
5593 -- We can mark the entity as known to be non-null if either it is
5594 -- safe to capture the value, or in the case of an IN parameter,
5595 -- which is a constant, if the check we just installed is in the
5596 -- declarative region of the subprogram body. In this latter case,
5597 -- a check is decisive for the rest of the body if the expression
5598 -- is sure to be elaborated, since we know we have to elaborate
5599 -- all declarations before executing the body.
5601 -- Couldn't this always be part of Safe_To_Capture_Value ???
5603 if Safe_To_Capture_Value (N, Entity (N))
5604 or else Safe_To_Capture_In_Parameter_Value
5606 Set_Is_Known_Non_Null (Entity (N));
5611 -- Start of processing for Install_Null_Excluding_Check
5614 pragma Assert (Is_Access_Type (Typ));
5616 -- No check inside a generic (why not???)
5618 if Inside_A_Generic then
5622 -- No check needed if known to be non-null
5624 if Known_Non_Null (N) then
5628 -- If known to be null, here is where we generate a compile time check
5630 if Known_Null (N) then
5632 -- Avoid generating warning message inside init procs
5634 if not Inside_Init_Proc then
5635 Apply_Compile_Time_Constraint_Error
5637 "null value not allowed here?",
5638 CE_Access_Check_Failed);
5641 Make_Raise_Constraint_Error (Loc,
5642 Reason => CE_Access_Check_Failed));
5649 -- If entity is never assigned, for sure a warning is appropriate
5651 if Is_Entity_Name (N) then
5652 Check_Unset_Reference (N);
5655 -- No check needed if checks are suppressed on the range. Note that we
5656 -- don't set Is_Known_Non_Null in this case (we could legitimately do
5657 -- so, since the program is erroneous, but we don't like to casually
5658 -- propagate such conclusions from erroneosity).
5660 if Access_Checks_Suppressed (Typ) then
5664 -- No check needed for access to concurrent record types generated by
5665 -- the expander. This is not just an optimization (though it does indeed
5666 -- remove junk checks). It also avoids generation of junk warnings.
5668 if Nkind (N) in N_Has_Chars
5669 and then Chars (N) = Name_uObject
5670 and then Is_Concurrent_Record_Type
5671 (Directly_Designated_Type (Etype (N)))
5676 -- No check needed for the Get_Current_Excep.all.all idiom generated by
5677 -- the expander within exception handlers, since we know that the value
5678 -- can never be null.
5680 -- Is this really the right way to do this? Normally we generate such
5681 -- code in the expander with checks off, and that's how we suppress this
5682 -- kind of junk check ???
5684 if Nkind (N) = N_Function_Call
5685 and then Nkind (Name (N)) = N_Explicit_Dereference
5686 and then Nkind (Prefix (Name (N))) = N_Identifier
5687 and then Is_RTE (Entity (Prefix (Name (N))), RE_Get_Current_Excep)
5692 -- Otherwise install access check
5695 Make_Raise_Constraint_Error (Loc,
5698 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
5699 Right_Opnd => Make_Null (Loc)),
5700 Reason => CE_Access_Check_Failed));
5703 end Install_Null_Excluding_Check;
5705 --------------------------
5706 -- Install_Static_Check --
5707 --------------------------
5709 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
5710 Stat : constant Boolean := Is_Static_Expression (R_Cno);
5711 Typ : constant Entity_Id := Etype (R_Cno);
5715 Make_Raise_Constraint_Error (Loc,
5716 Reason => CE_Range_Check_Failed));
5717 Set_Analyzed (R_Cno);
5718 Set_Etype (R_Cno, Typ);
5719 Set_Raises_Constraint_Error (R_Cno);
5720 Set_Is_Static_Expression (R_Cno, Stat);
5722 -- Now deal with possible local raise handling
5724 Possible_Local_Raise (R_Cno, Standard_Constraint_Error);
5725 end Install_Static_Check;
5727 ---------------------
5728 -- Kill_All_Checks --
5729 ---------------------
5731 procedure Kill_All_Checks is
5733 if Debug_Flag_CC then
5734 w ("Kill_All_Checks");
5737 -- We reset the number of saved checks to zero, and also modify all
5738 -- stack entries for statement ranges to indicate that the number of
5739 -- checks at each level is now zero.
5741 Num_Saved_Checks := 0;
5743 -- Note: the Int'Min here avoids any possibility of J being out of
5744 -- range when called from e.g. Conditional_Statements_Begin.
5746 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
5747 Saved_Checks_Stack (J) := 0;
5749 end Kill_All_Checks;
5755 procedure Kill_Checks (V : Entity_Id) is
5757 if Debug_Flag_CC then
5758 w ("Kill_Checks for entity", Int (V));
5761 for J in 1 .. Num_Saved_Checks loop
5762 if Saved_Checks (J).Entity = V then
5763 if Debug_Flag_CC then
5764 w (" Checks killed for saved check ", J);
5767 Saved_Checks (J).Killed := True;
5772 ------------------------------
5773 -- Length_Checks_Suppressed --
5774 ------------------------------
5776 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
5778 if Present (E) and then Checks_May_Be_Suppressed (E) then
5779 return Is_Check_Suppressed (E, Length_Check);
5781 return Scope_Suppress (Length_Check);
5783 end Length_Checks_Suppressed;
5785 --------------------------------
5786 -- Overflow_Checks_Suppressed --
5787 --------------------------------
5789 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
5791 if Present (E) and then Checks_May_Be_Suppressed (E) then
5792 return Is_Check_Suppressed (E, Overflow_Check);
5794 return Scope_Suppress (Overflow_Check);
5796 end Overflow_Checks_Suppressed;
5798 -----------------------------
5799 -- Range_Checks_Suppressed --
5800 -----------------------------
5802 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
5806 -- Note: for now we always suppress range checks on Vax float types,
5807 -- since Gigi does not know how to generate these checks.
5809 if Vax_Float (E) then
5811 elsif Kill_Range_Checks (E) then
5813 elsif Checks_May_Be_Suppressed (E) then
5814 return Is_Check_Suppressed (E, Range_Check);
5818 return Scope_Suppress (Range_Check);
5819 end Range_Checks_Suppressed;
5821 -----------------------------------------
5822 -- Range_Or_Validity_Checks_Suppressed --
5823 -----------------------------------------
5825 -- Note: the coding would be simpler here if we simply made appropriate
5826 -- calls to Range/Validity_Checks_Suppressed, but that would result in
5827 -- duplicated checks which we prefer to avoid.
5829 function Range_Or_Validity_Checks_Suppressed
5830 (Expr : Node_Id) return Boolean
5833 -- Immediate return if scope checks suppressed for either check
5835 if Scope_Suppress (Range_Check) or Scope_Suppress (Validity_Check) then
5839 -- If no expression, that's odd, decide that checks are suppressed,
5840 -- since we don't want anyone trying to do checks in this case, which
5841 -- is most likely the result of some other error.
5847 -- Expression is present, so perform suppress checks on type
5850 Typ : constant Entity_Id := Etype (Expr);
5852 if Vax_Float (Typ) then
5854 elsif Checks_May_Be_Suppressed (Typ)
5855 and then (Is_Check_Suppressed (Typ, Range_Check)
5857 Is_Check_Suppressed (Typ, Validity_Check))
5863 -- If expression is an entity name, perform checks on this entity
5865 if Is_Entity_Name (Expr) then
5867 Ent : constant Entity_Id := Entity (Expr);
5869 if Checks_May_Be_Suppressed (Ent) then
5870 return Is_Check_Suppressed (Ent, Range_Check)
5871 or else Is_Check_Suppressed (Ent, Validity_Check);
5876 -- If we fall through, no checks suppressed
5879 end Range_Or_Validity_Checks_Suppressed;
5885 procedure Remove_Checks (Expr : Node_Id) is
5886 function Process (N : Node_Id) return Traverse_Result;
5887 -- Process a single node during the traversal
5889 procedure Traverse is new Traverse_Proc (Process);
5890 -- The traversal procedure itself
5896 function Process (N : Node_Id) return Traverse_Result is
5898 if Nkind (N) not in N_Subexpr then
5902 Set_Do_Range_Check (N, False);
5906 Traverse (Left_Opnd (N));
5909 when N_Attribute_Reference =>
5910 Set_Do_Overflow_Check (N, False);
5912 when N_Function_Call =>
5913 Set_Do_Tag_Check (N, False);
5916 Set_Do_Overflow_Check (N, False);
5920 Set_Do_Division_Check (N, False);
5923 Set_Do_Length_Check (N, False);
5926 Set_Do_Division_Check (N, False);
5929 Set_Do_Length_Check (N, False);
5932 Set_Do_Division_Check (N, False);
5935 Set_Do_Length_Check (N, False);
5942 Traverse (Left_Opnd (N));
5945 when N_Selected_Component =>
5946 Set_Do_Discriminant_Check (N, False);
5948 when N_Type_Conversion =>
5949 Set_Do_Length_Check (N, False);
5950 Set_Do_Tag_Check (N, False);
5951 Set_Do_Overflow_Check (N, False);
5960 -- Start of processing for Remove_Checks
5966 ----------------------------
5967 -- Selected_Length_Checks --
5968 ----------------------------
5970 function Selected_Length_Checks
5972 Target_Typ : Entity_Id;
5973 Source_Typ : Entity_Id;
5974 Warn_Node : Node_Id) return Check_Result
5976 Loc : constant Source_Ptr := Sloc (Ck_Node);
5979 Expr_Actual : Node_Id;
5981 Cond : Node_Id := Empty;
5982 Do_Access : Boolean := False;
5983 Wnode : Node_Id := Warn_Node;
5984 Ret_Result : Check_Result := (Empty, Empty);
5985 Num_Checks : Natural := 0;
5987 procedure Add_Check (N : Node_Id);
5988 -- Adds the action given to Ret_Result if N is non-Empty
5990 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
5991 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
5992 -- Comments required ???
5994 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
5995 -- True for equal literals and for nodes that denote the same constant
5996 -- entity, even if its value is not a static constant. This includes the
5997 -- case of a discriminal reference within an init proc. Removes some
5998 -- obviously superfluous checks.
6000 function Length_E_Cond
6001 (Exptyp : Entity_Id;
6003 Indx : Nat) return Node_Id;
6004 -- Returns expression to compute:
6005 -- Typ'Length /= Exptyp'Length
6007 function Length_N_Cond
6010 Indx : Nat) return Node_Id;
6011 -- Returns expression to compute:
6012 -- Typ'Length /= Expr'Length
6018 procedure Add_Check (N : Node_Id) is
6022 -- For now, ignore attempt to place more than 2 checks ???
6024 if Num_Checks = 2 then
6028 pragma Assert (Num_Checks <= 1);
6029 Num_Checks := Num_Checks + 1;
6030 Ret_Result (Num_Checks) := N;
6038 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
6039 SE : constant Entity_Id := Scope (E);
6041 E1 : Entity_Id := E;
6044 if Ekind (Scope (E)) = E_Record_Type
6045 and then Has_Discriminants (Scope (E))
6047 N := Build_Discriminal_Subtype_Of_Component (E);
6050 Insert_Action (Ck_Node, N);
6051 E1 := Defining_Identifier (N);
6055 if Ekind (E1) = E_String_Literal_Subtype then
6057 Make_Integer_Literal (Loc,
6058 Intval => String_Literal_Length (E1));
6060 elsif SE /= Standard_Standard
6061 and then Ekind (Scope (SE)) = E_Protected_Type
6062 and then Has_Discriminants (Scope (SE))
6063 and then Has_Completion (Scope (SE))
6064 and then not Inside_Init_Proc
6066 -- If the type whose length is needed is a private component
6067 -- constrained by a discriminant, we must expand the 'Length
6068 -- attribute into an explicit computation, using the discriminal
6069 -- of the current protected operation. This is because the actual
6070 -- type of the prival is constructed after the protected opera-
6071 -- tion has been fully expanded.
6074 Indx_Type : Node_Id;
6077 Do_Expand : Boolean := False;
6080 Indx_Type := First_Index (E);
6082 for J in 1 .. Indx - 1 loop
6083 Next_Index (Indx_Type);
6086 Get_Index_Bounds (Indx_Type, Lo, Hi);
6088 if Nkind (Lo) = N_Identifier
6089 and then Ekind (Entity (Lo)) = E_In_Parameter
6091 Lo := Get_Discriminal (E, Lo);
6095 if Nkind (Hi) = N_Identifier
6096 and then Ekind (Entity (Hi)) = E_In_Parameter
6098 Hi := Get_Discriminal (E, Hi);
6103 if not Is_Entity_Name (Lo) then
6104 Lo := Duplicate_Subexpr_No_Checks (Lo);
6107 if not Is_Entity_Name (Hi) then
6108 Lo := Duplicate_Subexpr_No_Checks (Hi);
6114 Make_Op_Subtract (Loc,
6118 Right_Opnd => Make_Integer_Literal (Loc, 1));
6123 Make_Attribute_Reference (Loc,
6124 Attribute_Name => Name_Length,
6126 New_Occurrence_Of (E1, Loc));
6129 Set_Expressions (N, New_List (
6130 Make_Integer_Literal (Loc, Indx)));
6139 Make_Attribute_Reference (Loc,
6140 Attribute_Name => Name_Length,
6142 New_Occurrence_Of (E1, Loc));
6145 Set_Expressions (N, New_List (
6146 Make_Integer_Literal (Loc, Indx)));
6157 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
6160 Make_Attribute_Reference (Loc,
6161 Attribute_Name => Name_Length,
6163 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6164 Expressions => New_List (
6165 Make_Integer_Literal (Loc, Indx)));
6172 function Length_E_Cond
6173 (Exptyp : Entity_Id;
6175 Indx : Nat) return Node_Id
6180 Left_Opnd => Get_E_Length (Typ, Indx),
6181 Right_Opnd => Get_E_Length (Exptyp, Indx));
6188 function Length_N_Cond
6191 Indx : Nat) return Node_Id
6196 Left_Opnd => Get_E_Length (Typ, Indx),
6197 Right_Opnd => Get_N_Length (Expr, Indx));
6204 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
6207 (Nkind (L) = N_Integer_Literal
6208 and then Nkind (R) = N_Integer_Literal
6209 and then Intval (L) = Intval (R))
6213 and then Ekind (Entity (L)) = E_Constant
6214 and then ((Is_Entity_Name (R)
6215 and then Entity (L) = Entity (R))
6217 (Nkind (R) = N_Type_Conversion
6218 and then Is_Entity_Name (Expression (R))
6219 and then Entity (L) = Entity (Expression (R)))))
6223 and then Ekind (Entity (R)) = E_Constant
6224 and then Nkind (L) = N_Type_Conversion
6225 and then Is_Entity_Name (Expression (L))
6226 and then Entity (R) = Entity (Expression (L)))
6230 and then Is_Entity_Name (R)
6231 and then Entity (L) = Entity (R)
6232 and then Ekind (Entity (L)) = E_In_Parameter
6233 and then Inside_Init_Proc);
6236 -- Start of processing for Selected_Length_Checks
6239 if not Full_Expander_Active then
6243 if Target_Typ = Any_Type
6244 or else Target_Typ = Any_Composite
6245 or else Raises_Constraint_Error (Ck_Node)
6254 T_Typ := Target_Typ;
6256 if No (Source_Typ) then
6257 S_Typ := Etype (Ck_Node);
6259 S_Typ := Source_Typ;
6262 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6266 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6267 S_Typ := Designated_Type (S_Typ);
6268 T_Typ := Designated_Type (T_Typ);
6271 -- A simple optimization for the null case
6273 if Known_Null (Ck_Node) then
6278 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6279 if Is_Constrained (T_Typ) then
6281 -- The checking code to be generated will freeze the
6282 -- corresponding array type. However, we must freeze the
6283 -- type now, so that the freeze node does not appear within
6284 -- the generated conditional expression, but ahead of it.
6286 Freeze_Before (Ck_Node, T_Typ);
6288 Expr_Actual := Get_Referenced_Object (Ck_Node);
6289 Exptyp := Get_Actual_Subtype (Ck_Node);
6291 if Is_Access_Type (Exptyp) then
6292 Exptyp := Designated_Type (Exptyp);
6295 -- String_Literal case. This needs to be handled specially be-
6296 -- cause no index types are available for string literals. The
6297 -- condition is simply:
6299 -- T_Typ'Length = string-literal-length
6301 if Nkind (Expr_Actual) = N_String_Literal
6302 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
6306 Left_Opnd => Get_E_Length (T_Typ, 1),
6308 Make_Integer_Literal (Loc,
6310 String_Literal_Length (Etype (Expr_Actual))));
6312 -- General array case. Here we have a usable actual subtype for
6313 -- the expression, and the condition is built from the two types
6316 -- T_Typ'Length /= Exptyp'Length or else
6317 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
6318 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
6321 elsif Is_Constrained (Exptyp) then
6323 Ndims : constant Nat := Number_Dimensions (T_Typ);
6336 -- At the library level, we need to ensure that the type of
6337 -- the object is elaborated before the check itself is
6338 -- emitted. This is only done if the object is in the
6339 -- current compilation unit, otherwise the type is frozen
6340 -- and elaborated in its unit.
6342 if Is_Itype (Exptyp)
6344 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
6346 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
6347 and then In_Open_Scopes (Scope (Exptyp))
6349 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
6350 Set_Itype (Ref_Node, Exptyp);
6351 Insert_Action (Ck_Node, Ref_Node);
6354 L_Index := First_Index (T_Typ);
6355 R_Index := First_Index (Exptyp);
6357 for Indx in 1 .. Ndims loop
6358 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6360 Nkind (R_Index) = N_Raise_Constraint_Error)
6362 Get_Index_Bounds (L_Index, L_Low, L_High);
6363 Get_Index_Bounds (R_Index, R_Low, R_High);
6365 -- Deal with compile time length check. Note that we
6366 -- skip this in the access case, because the access
6367 -- value may be null, so we cannot know statically.
6370 and then Compile_Time_Known_Value (L_Low)
6371 and then Compile_Time_Known_Value (L_High)
6372 and then Compile_Time_Known_Value (R_Low)
6373 and then Compile_Time_Known_Value (R_High)
6375 if Expr_Value (L_High) >= Expr_Value (L_Low) then
6376 L_Length := Expr_Value (L_High) -
6377 Expr_Value (L_Low) + 1;
6379 L_Length := UI_From_Int (0);
6382 if Expr_Value (R_High) >= Expr_Value (R_Low) then
6383 R_Length := Expr_Value (R_High) -
6384 Expr_Value (R_Low) + 1;
6386 R_Length := UI_From_Int (0);
6389 if L_Length > R_Length then
6391 (Compile_Time_Constraint_Error
6392 (Wnode, "too few elements for}?", T_Typ));
6394 elsif L_Length < R_Length then
6396 (Compile_Time_Constraint_Error
6397 (Wnode, "too many elements for}?", T_Typ));
6400 -- The comparison for an individual index subtype
6401 -- is omitted if the corresponding index subtypes
6402 -- statically match, since the result is known to
6403 -- be true. Note that this test is worth while even
6404 -- though we do static evaluation, because non-static
6405 -- subtypes can statically match.
6408 Subtypes_Statically_Match
6409 (Etype (L_Index), Etype (R_Index))
6412 (Same_Bounds (L_Low, R_Low)
6413 and then Same_Bounds (L_High, R_High))
6416 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
6425 -- Handle cases where we do not get a usable actual subtype that
6426 -- is constrained. This happens for example in the function call
6427 -- and explicit dereference cases. In these cases, we have to get
6428 -- the length or range from the expression itself, making sure we
6429 -- do not evaluate it more than once.
6431 -- Here Ck_Node is the original expression, or more properly the
6432 -- result of applying Duplicate_Expr to the original tree, forcing
6433 -- the result to be a name.
6437 Ndims : constant Nat := Number_Dimensions (T_Typ);
6440 -- Build the condition for the explicit dereference case
6442 for Indx in 1 .. Ndims loop
6444 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
6451 -- Construct the test and insert into the tree
6453 if Present (Cond) then
6455 Cond := Guard_Access (Cond, Loc, Ck_Node);
6459 (Make_Raise_Constraint_Error (Loc,
6461 Reason => CE_Length_Check_Failed));
6465 end Selected_Length_Checks;
6467 ---------------------------
6468 -- Selected_Range_Checks --
6469 ---------------------------
6471 function Selected_Range_Checks
6473 Target_Typ : Entity_Id;
6474 Source_Typ : Entity_Id;
6475 Warn_Node : Node_Id) return Check_Result
6477 Loc : constant Source_Ptr := Sloc (Ck_Node);
6480 Expr_Actual : Node_Id;
6482 Cond : Node_Id := Empty;
6483 Do_Access : Boolean := False;
6484 Wnode : Node_Id := Warn_Node;
6485 Ret_Result : Check_Result := (Empty, Empty);
6486 Num_Checks : Integer := 0;
6488 procedure Add_Check (N : Node_Id);
6489 -- Adds the action given to Ret_Result if N is non-Empty
6491 function Discrete_Range_Cond
6493 Typ : Entity_Id) return Node_Id;
6494 -- Returns expression to compute:
6495 -- Low_Bound (Expr) < Typ'First
6497 -- High_Bound (Expr) > Typ'Last
6499 function Discrete_Expr_Cond
6501 Typ : Entity_Id) return Node_Id;
6502 -- Returns expression to compute:
6507 function Get_E_First_Or_Last
6511 Nam : Name_Id) return Node_Id;
6512 -- Returns an attribute reference
6513 -- E'First or E'Last
6514 -- with a source location of Loc.
6516 -- Nam is Name_First or Name_Last, according to which attribute is
6517 -- desired. If Indx is non-zero, it is passed as a literal in the
6518 -- Expressions of the attribute reference (identifying the desired
6519 -- array dimension).
6521 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
6522 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
6523 -- Returns expression to compute:
6524 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
6526 function Range_E_Cond
6527 (Exptyp : Entity_Id;
6531 -- Returns expression to compute:
6532 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
6534 function Range_Equal_E_Cond
6535 (Exptyp : Entity_Id;
6537 Indx : Nat) return Node_Id;
6538 -- Returns expression to compute:
6539 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
6541 function Range_N_Cond
6544 Indx : Nat) return Node_Id;
6545 -- Return expression to compute:
6546 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
6552 procedure Add_Check (N : Node_Id) is
6556 -- For now, ignore attempt to place more than 2 checks ???
6558 if Num_Checks = 2 then
6562 pragma Assert (Num_Checks <= 1);
6563 Num_Checks := Num_Checks + 1;
6564 Ret_Result (Num_Checks) := N;
6568 -------------------------
6569 -- Discrete_Expr_Cond --
6570 -------------------------
6572 function Discrete_Expr_Cond
6574 Typ : Entity_Id) return Node_Id
6582 Convert_To (Base_Type (Typ),
6583 Duplicate_Subexpr_No_Checks (Expr)),
6585 Convert_To (Base_Type (Typ),
6586 Get_E_First_Or_Last (Loc, Typ, 0, Name_First))),
6591 Convert_To (Base_Type (Typ),
6592 Duplicate_Subexpr_No_Checks (Expr)),
6596 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last))));
6597 end Discrete_Expr_Cond;
6599 -------------------------
6600 -- Discrete_Range_Cond --
6601 -------------------------
6603 function Discrete_Range_Cond
6605 Typ : Entity_Id) return Node_Id
6607 LB : Node_Id := Low_Bound (Expr);
6608 HB : Node_Id := High_Bound (Expr);
6610 Left_Opnd : Node_Id;
6611 Right_Opnd : Node_Id;
6614 if Nkind (LB) = N_Identifier
6615 and then Ekind (Entity (LB)) = E_Discriminant
6617 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6620 if Nkind (HB) = N_Identifier
6621 and then Ekind (Entity (HB)) = E_Discriminant
6623 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6630 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
6635 Get_E_First_Or_Last (Loc, Typ, 0, Name_First)));
6637 if Base_Type (Typ) = Typ then
6640 elsif Compile_Time_Known_Value (High_Bound (Scalar_Range (Typ)))
6642 Compile_Time_Known_Value (High_Bound (Scalar_Range
6645 if Is_Floating_Point_Type (Typ) then
6646 if Expr_Value_R (High_Bound (Scalar_Range (Typ))) =
6647 Expr_Value_R (High_Bound (Scalar_Range (Base_Type (Typ))))
6653 if Expr_Value (High_Bound (Scalar_Range (Typ))) =
6654 Expr_Value (High_Bound (Scalar_Range (Base_Type (Typ))))
6665 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
6670 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last)));
6672 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
6673 end Discrete_Range_Cond;
6675 -------------------------
6676 -- Get_E_First_Or_Last --
6677 -------------------------
6679 function Get_E_First_Or_Last
6683 Nam : Name_Id) return Node_Id
6688 Exprs := New_List (Make_Integer_Literal (Loc, UI_From_Int (Indx)));
6693 return Make_Attribute_Reference (Loc,
6694 Prefix => New_Occurrence_Of (E, Loc),
6695 Attribute_Name => Nam,
6696 Expressions => Exprs);
6697 end Get_E_First_Or_Last;
6703 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
6706 Make_Attribute_Reference (Loc,
6707 Attribute_Name => Name_First,
6709 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6710 Expressions => New_List (
6711 Make_Integer_Literal (Loc, Indx)));
6718 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
6721 Make_Attribute_Reference (Loc,
6722 Attribute_Name => Name_Last,
6724 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6725 Expressions => New_List (
6726 Make_Integer_Literal (Loc, Indx)));
6733 function Range_E_Cond
6734 (Exptyp : Entity_Id;
6736 Indx : Nat) return Node_Id
6744 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
6746 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
6751 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
6753 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
6756 ------------------------
6757 -- Range_Equal_E_Cond --
6758 ------------------------
6760 function Range_Equal_E_Cond
6761 (Exptyp : Entity_Id;
6763 Indx : Nat) return Node_Id
6771 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
6773 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
6778 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
6780 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
6781 end Range_Equal_E_Cond;
6787 function Range_N_Cond
6790 Indx : Nat) return Node_Id
6798 Get_N_First (Expr, Indx),
6800 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
6805 Get_N_Last (Expr, Indx),
6807 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
6810 -- Start of processing for Selected_Range_Checks
6813 if not Full_Expander_Active then
6817 if Target_Typ = Any_Type
6818 or else Target_Typ = Any_Composite
6819 or else Raises_Constraint_Error (Ck_Node)
6828 T_Typ := Target_Typ;
6830 if No (Source_Typ) then
6831 S_Typ := Etype (Ck_Node);
6833 S_Typ := Source_Typ;
6836 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6840 -- The order of evaluating T_Typ before S_Typ seems to be critical
6841 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
6842 -- in, and since Node can be an N_Range node, it might be invalid.
6843 -- Should there be an assert check somewhere for taking the Etype of
6844 -- an N_Range node ???
6846 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6847 S_Typ := Designated_Type (S_Typ);
6848 T_Typ := Designated_Type (T_Typ);
6851 -- A simple optimization for the null case
6853 if Known_Null (Ck_Node) then
6858 -- For an N_Range Node, check for a null range and then if not
6859 -- null generate a range check action.
6861 if Nkind (Ck_Node) = N_Range then
6863 -- There's no point in checking a range against itself
6865 if Ck_Node = Scalar_Range (T_Typ) then
6870 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
6871 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
6872 Known_T_LB : constant Boolean := Compile_Time_Known_Value (T_LB);
6873 Known_T_HB : constant Boolean := Compile_Time_Known_Value (T_HB);
6875 LB : Node_Id := Low_Bound (Ck_Node);
6876 HB : Node_Id := High_Bound (Ck_Node);
6880 Null_Range : Boolean;
6881 Out_Of_Range_L : Boolean;
6882 Out_Of_Range_H : Boolean;
6885 -- Compute what is known at compile time
6887 if Known_T_LB and Known_T_HB then
6888 if Compile_Time_Known_Value (LB) then
6891 -- There's no point in checking that a bound is within its
6892 -- own range so pretend that it is known in this case. First
6893 -- deal with low bound.
6895 elsif Ekind (Etype (LB)) = E_Signed_Integer_Subtype
6896 and then Scalar_Range (Etype (LB)) = Scalar_Range (T_Typ)
6905 -- Likewise for the high bound
6907 if Compile_Time_Known_Value (HB) then
6910 elsif Ekind (Etype (HB)) = E_Signed_Integer_Subtype
6911 and then Scalar_Range (Etype (HB)) = Scalar_Range (T_Typ)
6921 -- Check for case where everything is static and we can do the
6922 -- check at compile time. This is skipped if we have an access
6923 -- type, since the access value may be null.
6925 -- ??? This code can be improved since you only need to know that
6926 -- the two respective bounds (LB & T_LB or HB & T_HB) are known at
6927 -- compile time to emit pertinent messages.
6929 if Known_T_LB and Known_T_HB and Known_LB and Known_HB
6932 -- Floating-point case
6934 if Is_Floating_Point_Type (S_Typ) then
6935 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
6937 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
6939 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
6942 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
6944 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
6946 -- Fixed or discrete type case
6949 Null_Range := Expr_Value (HB) < Expr_Value (LB);
6951 (Expr_Value (LB) < Expr_Value (T_LB))
6953 (Expr_Value (LB) > Expr_Value (T_HB));
6956 (Expr_Value (HB) > Expr_Value (T_HB))
6958 (Expr_Value (HB) < Expr_Value (T_LB));
6961 if not Null_Range then
6962 if Out_Of_Range_L then
6963 if No (Warn_Node) then
6965 (Compile_Time_Constraint_Error
6966 (Low_Bound (Ck_Node),
6967 "static value out of range of}?", T_Typ));
6971 (Compile_Time_Constraint_Error
6973 "static range out of bounds of}?", T_Typ));
6977 if Out_Of_Range_H then
6978 if No (Warn_Node) then
6980 (Compile_Time_Constraint_Error
6981 (High_Bound (Ck_Node),
6982 "static value out of range of}?", T_Typ));
6986 (Compile_Time_Constraint_Error
6988 "static range out of bounds of}?", T_Typ));
6995 LB : Node_Id := Low_Bound (Ck_Node);
6996 HB : Node_Id := High_Bound (Ck_Node);
6999 -- If either bound is a discriminant and we are within the
7000 -- record declaration, it is a use of the discriminant in a
7001 -- constraint of a component, and nothing can be checked
7002 -- here. The check will be emitted within the init proc.
7003 -- Before then, the discriminal has no real meaning.
7004 -- Similarly, if the entity is a discriminal, there is no
7005 -- check to perform yet.
7007 -- The same holds within a discriminated synchronized type,
7008 -- where the discriminant may constrain a component or an
7011 if Nkind (LB) = N_Identifier
7012 and then Denotes_Discriminant (LB, True)
7014 if Current_Scope = Scope (Entity (LB))
7015 or else Is_Concurrent_Type (Current_Scope)
7016 or else Ekind (Entity (LB)) /= E_Discriminant
7021 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
7025 if Nkind (HB) = N_Identifier
7026 and then Denotes_Discriminant (HB, True)
7028 if Current_Scope = Scope (Entity (HB))
7029 or else Is_Concurrent_Type (Current_Scope)
7030 or else Ekind (Entity (HB)) /= E_Discriminant
7035 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
7039 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
7040 Set_Paren_Count (Cond, 1);
7046 Left_Opnd => Duplicate_Subexpr_No_Checks (HB),
7047 Right_Opnd => Duplicate_Subexpr_No_Checks (LB)),
7048 Right_Opnd => Cond);
7053 elsif Is_Scalar_Type (S_Typ) then
7055 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
7056 -- except the above simply sets a flag in the node and lets
7057 -- gigi generate the check base on the Etype of the expression.
7058 -- Sometimes, however we want to do a dynamic check against an
7059 -- arbitrary target type, so we do that here.
7061 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
7062 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
7064 -- For literals, we can tell if the constraint error will be
7065 -- raised at compile time, so we never need a dynamic check, but
7066 -- if the exception will be raised, then post the usual warning,
7067 -- and replace the literal with a raise constraint error
7068 -- expression. As usual, skip this for access types
7070 elsif Compile_Time_Known_Value (Ck_Node)
7071 and then not Do_Access
7074 LB : constant Node_Id := Type_Low_Bound (T_Typ);
7075 UB : constant Node_Id := Type_High_Bound (T_Typ);
7077 Out_Of_Range : Boolean;
7078 Static_Bounds : constant Boolean :=
7079 Compile_Time_Known_Value (LB)
7080 and Compile_Time_Known_Value (UB);
7083 -- Following range tests should use Sem_Eval routine ???
7085 if Static_Bounds then
7086 if Is_Floating_Point_Type (S_Typ) then
7088 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
7090 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
7092 -- Fixed or discrete type
7096 Expr_Value (Ck_Node) < Expr_Value (LB)
7098 Expr_Value (Ck_Node) > Expr_Value (UB);
7101 -- Bounds of the type are static and the literal is out of
7102 -- range so output a warning message.
7104 if Out_Of_Range then
7105 if No (Warn_Node) then
7107 (Compile_Time_Constraint_Error
7109 "static value out of range of}?", T_Typ));
7113 (Compile_Time_Constraint_Error
7115 "static value out of range of}?", T_Typ));
7120 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
7124 -- Here for the case of a non-static expression, we need a runtime
7125 -- check unless the source type range is guaranteed to be in the
7126 -- range of the target type.
7129 if not In_Subrange_Of (S_Typ, T_Typ) then
7130 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
7135 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
7136 if Is_Constrained (T_Typ) then
7138 Expr_Actual := Get_Referenced_Object (Ck_Node);
7139 Exptyp := Get_Actual_Subtype (Expr_Actual);
7141 if Is_Access_Type (Exptyp) then
7142 Exptyp := Designated_Type (Exptyp);
7145 -- String_Literal case. This needs to be handled specially be-
7146 -- cause no index types are available for string literals. The
7147 -- condition is simply:
7149 -- T_Typ'Length = string-literal-length
7151 if Nkind (Expr_Actual) = N_String_Literal then
7154 -- General array case. Here we have a usable actual subtype for
7155 -- the expression, and the condition is built from the two types
7157 -- T_Typ'First < Exptyp'First or else
7158 -- T_Typ'Last > Exptyp'Last or else
7159 -- T_Typ'First(1) < Exptyp'First(1) or else
7160 -- T_Typ'Last(1) > Exptyp'Last(1) or else
7163 elsif Is_Constrained (Exptyp) then
7165 Ndims : constant Nat := Number_Dimensions (T_Typ);
7171 L_Index := First_Index (T_Typ);
7172 R_Index := First_Index (Exptyp);
7174 for Indx in 1 .. Ndims loop
7175 if not (Nkind (L_Index) = N_Raise_Constraint_Error
7177 Nkind (R_Index) = N_Raise_Constraint_Error)
7179 -- Deal with compile time length check. Note that we
7180 -- skip this in the access case, because the access
7181 -- value may be null, so we cannot know statically.
7184 Subtypes_Statically_Match
7185 (Etype (L_Index), Etype (R_Index))
7187 -- If the target type is constrained then we
7188 -- have to check for exact equality of bounds
7189 -- (required for qualified expressions).
7191 if Is_Constrained (T_Typ) then
7194 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
7197 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
7207 -- Handle cases where we do not get a usable actual subtype that
7208 -- is constrained. This happens for example in the function call
7209 -- and explicit dereference cases. In these cases, we have to get
7210 -- the length or range from the expression itself, making sure we
7211 -- do not evaluate it more than once.
7213 -- Here Ck_Node is the original expression, or more properly the
7214 -- result of applying Duplicate_Expr to the original tree,
7215 -- forcing the result to be a name.
7219 Ndims : constant Nat := Number_Dimensions (T_Typ);
7222 -- Build the condition for the explicit dereference case
7224 for Indx in 1 .. Ndims loop
7226 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
7232 -- For a conversion to an unconstrained array type, generate an
7233 -- Action to check that the bounds of the source value are within
7234 -- the constraints imposed by the target type (RM 4.6(38)). No
7235 -- check is needed for a conversion to an access to unconstrained
7236 -- array type, as 4.6(24.15/2) requires the designated subtypes
7237 -- of the two access types to statically match.
7239 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
7240 and then not Do_Access
7243 Opnd_Index : Node_Id;
7244 Targ_Index : Node_Id;
7245 Opnd_Range : Node_Id;
7248 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
7249 Targ_Index := First_Index (T_Typ);
7250 while Present (Opnd_Index) loop
7252 -- If the index is a range, use its bounds. If it is an
7253 -- entity (as will be the case if it is a named subtype
7254 -- or an itype created for a slice) retrieve its range.
7256 if Is_Entity_Name (Opnd_Index)
7257 and then Is_Type (Entity (Opnd_Index))
7259 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
7261 Opnd_Range := Opnd_Index;
7264 if Nkind (Opnd_Range) = N_Range then
7266 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7267 Assume_Valid => True)
7270 (High_Bound (Opnd_Range), Etype (Targ_Index),
7271 Assume_Valid => True)
7275 -- If null range, no check needed
7278 Compile_Time_Known_Value (High_Bound (Opnd_Range))
7280 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
7282 Expr_Value (High_Bound (Opnd_Range)) <
7283 Expr_Value (Low_Bound (Opnd_Range))
7287 elsif Is_Out_Of_Range
7288 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7289 Assume_Valid => True)
7292 (High_Bound (Opnd_Range), Etype (Targ_Index),
7293 Assume_Valid => True)
7296 (Compile_Time_Constraint_Error
7297 (Wnode, "value out of range of}?", T_Typ));
7303 (Opnd_Range, Etype (Targ_Index)));
7307 Next_Index (Opnd_Index);
7308 Next_Index (Targ_Index);
7315 -- Construct the test and insert into the tree
7317 if Present (Cond) then
7319 Cond := Guard_Access (Cond, Loc, Ck_Node);
7323 (Make_Raise_Constraint_Error (Loc,
7325 Reason => CE_Range_Check_Failed));
7329 end Selected_Range_Checks;
7331 -------------------------------
7332 -- Storage_Checks_Suppressed --
7333 -------------------------------
7335 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
7337 if Present (E) and then Checks_May_Be_Suppressed (E) then
7338 return Is_Check_Suppressed (E, Storage_Check);
7340 return Scope_Suppress (Storage_Check);
7342 end Storage_Checks_Suppressed;
7344 ---------------------------
7345 -- Tag_Checks_Suppressed --
7346 ---------------------------
7348 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
7351 if Kill_Tag_Checks (E) then
7353 elsif Checks_May_Be_Suppressed (E) then
7354 return Is_Check_Suppressed (E, Tag_Check);
7358 return Scope_Suppress (Tag_Check);
7359 end Tag_Checks_Suppressed;
7361 --------------------------
7362 -- Validity_Check_Range --
7363 --------------------------
7365 procedure Validity_Check_Range (N : Node_Id) is
7367 if Validity_Checks_On and Validity_Check_Operands then
7368 if Nkind (N) = N_Range then
7369 Ensure_Valid (Low_Bound (N));
7370 Ensure_Valid (High_Bound (N));
7373 end Validity_Check_Range;
7375 --------------------------------
7376 -- Validity_Checks_Suppressed --
7377 --------------------------------
7379 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
7381 if Present (E) and then Checks_May_Be_Suppressed (E) then
7382 return Is_Check_Suppressed (E, Validity_Check);
7384 return Scope_Suppress (Validity_Check);
7386 end Validity_Checks_Suppressed;