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 Effectively_Has_Constrained_Partial_View
1244 (Typ => Base_Type (T_Typ),
1245 Scop => Current_Scope)
1250 -- Nothing to do if the type is an Unchecked_Union
1252 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1256 -- Suppress checks if the subtypes are the same. the check must be
1257 -- preserved in an assignment to a formal, because the constraint is
1258 -- given by the actual.
1260 if Nkind (Original_Node (N)) /= N_Allocator
1262 or else not Is_Entity_Name (Lhs)
1263 or else No (Param_Entity (Lhs)))
1266 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1267 and then not Is_Aliased_View (Lhs)
1272 -- We can also eliminate checks on allocators with a subtype mark that
1273 -- coincides with the context type. The context type may be a subtype
1274 -- without a constraint (common case, a generic actual).
1276 elsif Nkind (Original_Node (N)) = N_Allocator
1277 and then Is_Entity_Name (Expression (Original_Node (N)))
1280 Alloc_Typ : constant Entity_Id :=
1281 Entity (Expression (Original_Node (N)));
1284 if Alloc_Typ = T_Typ
1285 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1286 and then Is_Entity_Name (
1287 Subtype_Indication (Parent (T_Typ)))
1288 and then Alloc_Typ = Base_Type (T_Typ))
1296 -- See if we have a case where the types are both constrained, and all
1297 -- the constraints are constants. In this case, we can do the check
1298 -- successfully at compile time.
1300 -- We skip this check for the case where the node is a rewritten`
1301 -- allocator, because it already carries the context subtype, and
1302 -- extracting the discriminants from the aggregate is messy.
1304 if Is_Constrained (S_Typ)
1305 and then Nkind (Original_Node (N)) /= N_Allocator
1315 -- S_Typ may not have discriminants in the case where it is a
1316 -- private type completed by a default discriminated type. In that
1317 -- case, we need to get the constraints from the underlying_type.
1318 -- If the underlying type is unconstrained (i.e. has no default
1319 -- discriminants) no check is needed.
1321 if Has_Discriminants (S_Typ) then
1322 Discr := First_Discriminant (S_Typ);
1323 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1326 Discr := First_Discriminant (Underlying_Type (S_Typ));
1329 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1335 -- A further optimization: if T_Typ is derived from S_Typ
1336 -- without imposing a constraint, no check is needed.
1338 if Nkind (Original_Node (Parent (T_Typ))) =
1339 N_Full_Type_Declaration
1342 Type_Def : constant Node_Id :=
1344 (Original_Node (Parent (T_Typ)));
1346 if Nkind (Type_Def) = N_Derived_Type_Definition
1347 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1348 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1356 DconT := First_Elmt (Discriminant_Constraint (T_Typ));
1358 while Present (Discr) loop
1359 ItemS := Node (DconS);
1360 ItemT := Node (DconT);
1362 -- For a discriminated component type constrained by the
1363 -- current instance of an enclosing type, there is no
1364 -- applicable discriminant check.
1366 if Nkind (ItemT) = N_Attribute_Reference
1367 and then Is_Access_Type (Etype (ItemT))
1368 and then Is_Entity_Name (Prefix (ItemT))
1369 and then Is_Type (Entity (Prefix (ItemT)))
1374 -- If the expressions for the discriminants are identical
1375 -- and it is side-effect free (for now just an entity),
1376 -- this may be a shared constraint, e.g. from a subtype
1377 -- without a constraint introduced as a generic actual.
1378 -- Examine other discriminants if any.
1381 and then Is_Entity_Name (ItemS)
1385 elsif not Is_OK_Static_Expression (ItemS)
1386 or else not Is_OK_Static_Expression (ItemT)
1390 elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
1391 if Do_Access then -- needs run-time check.
1394 Apply_Compile_Time_Constraint_Error
1395 (N, "incorrect value for discriminant&?",
1396 CE_Discriminant_Check_Failed, Ent => Discr);
1403 Next_Discriminant (Discr);
1412 -- Here we need a discriminant check. First build the expression
1413 -- for the comparisons of the discriminants:
1415 -- (n.disc1 /= typ.disc1) or else
1416 -- (n.disc2 /= typ.disc2) or else
1418 -- (n.discn /= typ.discn)
1420 Cond := Build_Discriminant_Checks (N, T_Typ);
1422 -- If Lhs is set and is a parameter, then the condition is
1423 -- guarded by: lhs'constrained and then (condition built above)
1425 if Present (Param_Entity (Lhs)) then
1429 Make_Attribute_Reference (Loc,
1430 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1431 Attribute_Name => Name_Constrained),
1432 Right_Opnd => Cond);
1436 Cond := Guard_Access (Cond, Loc, N);
1440 Make_Raise_Constraint_Error (Loc,
1442 Reason => CE_Discriminant_Check_Failed));
1443 end Apply_Discriminant_Check;
1445 ------------------------
1446 -- Apply_Divide_Check --
1447 ------------------------
1449 procedure Apply_Divide_Check (N : Node_Id) is
1450 Loc : constant Source_Ptr := Sloc (N);
1451 Typ : constant Entity_Id := Etype (N);
1452 Left : constant Node_Id := Left_Opnd (N);
1453 Right : constant Node_Id := Right_Opnd (N);
1463 pragma Warnings (Off, Lhi);
1464 -- Don't actually use this value
1467 if Full_Expander_Active
1468 and then not Backend_Divide_Checks_On_Target
1469 and then Check_Needed (Right, Division_Check)
1471 Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True);
1473 -- See if division by zero possible, and if so generate test. This
1474 -- part of the test is not controlled by the -gnato switch.
1476 if Do_Division_Check (N) then
1477 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1479 Make_Raise_Constraint_Error (Loc,
1482 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1483 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1484 Reason => CE_Divide_By_Zero));
1488 -- Test for extremely annoying case of xxx'First divided by -1
1490 if Do_Overflow_Check (N) then
1491 if Nkind (N) = N_Op_Divide
1492 and then Is_Signed_Integer_Type (Typ)
1494 Determine_Range (Left, LOK, Llo, Lhi, Assume_Valid => True);
1495 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1497 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1499 ((not LOK) or else (Llo = LLB))
1502 Make_Raise_Constraint_Error (Loc,
1508 Duplicate_Subexpr_Move_Checks (Left),
1509 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1513 Duplicate_Subexpr (Right),
1515 Make_Integer_Literal (Loc, -1))),
1516 Reason => CE_Overflow_Check_Failed));
1521 end Apply_Divide_Check;
1523 ----------------------------------
1524 -- Apply_Float_Conversion_Check --
1525 ----------------------------------
1527 -- Let F and I be the source and target types of the conversion. The RM
1528 -- specifies that a floating-point value X is rounded to the nearest
1529 -- integer, with halfway cases being rounded away from zero. The rounded
1530 -- value of X is checked against I'Range.
1532 -- The catch in the above paragraph is that there is no good way to know
1533 -- whether the round-to-integer operation resulted in overflow. A remedy is
1534 -- to perform a range check in the floating-point domain instead, however:
1536 -- (1) The bounds may not be known at compile time
1537 -- (2) The check must take into account rounding or truncation.
1538 -- (3) The range of type I may not be exactly representable in F.
1539 -- (4) For the rounding case, The end-points I'First - 0.5 and
1540 -- I'Last + 0.5 may or may not be in range, depending on the
1541 -- sign of I'First and I'Last.
1542 -- (5) X may be a NaN, which will fail any comparison
1544 -- The following steps correctly convert X with rounding:
1546 -- (1) If either I'First or I'Last is not known at compile time, use
1547 -- I'Base instead of I in the next three steps and perform a
1548 -- regular range check against I'Range after conversion.
1549 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1550 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1551 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1552 -- In other words, take one of the closest floating-point numbers
1553 -- (which is an integer value) to I'First, and see if it is in
1555 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1556 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1557 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1558 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1559 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1561 -- For the truncating case, replace steps (2) and (3) as follows:
1562 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1563 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1565 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1566 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1569 procedure Apply_Float_Conversion_Check
1571 Target_Typ : Entity_Id)
1573 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1574 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1575 Loc : constant Source_Ptr := Sloc (Ck_Node);
1576 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1577 Target_Base : constant Entity_Id :=
1578 Implementation_Base_Type (Target_Typ);
1580 Par : constant Node_Id := Parent (Ck_Node);
1581 pragma Assert (Nkind (Par) = N_Type_Conversion);
1582 -- Parent of check node, must be a type conversion
1584 Truncate : constant Boolean := Float_Truncate (Par);
1585 Max_Bound : constant Uint :=
1587 (Machine_Radix_Value (Expr_Type),
1588 Machine_Mantissa_Value (Expr_Type) - 1) - 1;
1590 -- Largest bound, so bound plus or minus half is a machine number of F
1592 Ifirst, Ilast : Uint;
1593 -- Bounds of integer type
1596 -- Bounds to check in floating-point domain
1598 Lo_OK, Hi_OK : Boolean;
1599 -- True iff Lo resp. Hi belongs to I'Range
1601 Lo_Chk, Hi_Chk : Node_Id;
1602 -- Expressions that are False iff check fails
1604 Reason : RT_Exception_Code;
1607 if not Compile_Time_Known_Value (LB)
1608 or not Compile_Time_Known_Value (HB)
1611 -- First check that the value falls in the range of the base type,
1612 -- to prevent overflow during conversion and then perform a
1613 -- regular range check against the (dynamic) bounds.
1615 pragma Assert (Target_Base /= Target_Typ);
1617 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Par);
1620 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1621 Set_Etype (Temp, Target_Base);
1623 Insert_Action (Parent (Par),
1624 Make_Object_Declaration (Loc,
1625 Defining_Identifier => Temp,
1626 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1627 Expression => New_Copy_Tree (Par)),
1628 Suppress => All_Checks);
1631 Make_Raise_Constraint_Error (Loc,
1634 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1635 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1636 Reason => CE_Range_Check_Failed));
1637 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
1643 -- Get the (static) bounds of the target type
1645 Ifirst := Expr_Value (LB);
1646 Ilast := Expr_Value (HB);
1648 -- A simple optimization: if the expression is a universal literal,
1649 -- we can do the comparison with the bounds and the conversion to
1650 -- an integer type statically. The range checks are unchanged.
1652 if Nkind (Ck_Node) = N_Real_Literal
1653 and then Etype (Ck_Node) = Universal_Real
1654 and then Is_Integer_Type (Target_Typ)
1655 and then Nkind (Parent (Ck_Node)) = N_Type_Conversion
1658 Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node));
1661 if Int_Val <= Ilast and then Int_Val >= Ifirst then
1663 -- Conversion is safe
1665 Rewrite (Parent (Ck_Node),
1666 Make_Integer_Literal (Loc, UI_To_Int (Int_Val)));
1667 Analyze_And_Resolve (Parent (Ck_Node), Target_Typ);
1673 -- Check against lower bound
1675 if Truncate and then Ifirst > 0 then
1676 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
1680 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
1683 elsif abs (Ifirst) < Max_Bound then
1684 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
1685 Lo_OK := (Ifirst > 0);
1688 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
1689 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
1694 -- Lo_Chk := (X >= Lo)
1696 Lo_Chk := Make_Op_Ge (Loc,
1697 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1698 Right_Opnd => Make_Real_Literal (Loc, Lo));
1701 -- Lo_Chk := (X > Lo)
1703 Lo_Chk := Make_Op_Gt (Loc,
1704 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1705 Right_Opnd => Make_Real_Literal (Loc, Lo));
1708 -- Check against higher bound
1710 if Truncate and then Ilast < 0 then
1711 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
1715 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
1718 elsif abs (Ilast) < Max_Bound then
1719 Hi := UR_From_Uint (Ilast) + Ureal_Half;
1720 Hi_OK := (Ilast < 0);
1722 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
1723 Hi_OK := (Hi <= UR_From_Uint (Ilast));
1728 -- Hi_Chk := (X <= Hi)
1730 Hi_Chk := Make_Op_Le (Loc,
1731 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1732 Right_Opnd => Make_Real_Literal (Loc, Hi));
1735 -- Hi_Chk := (X < Hi)
1737 Hi_Chk := Make_Op_Lt (Loc,
1738 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1739 Right_Opnd => Make_Real_Literal (Loc, Hi));
1742 -- If the bounds of the target type are the same as those of the base
1743 -- type, the check is an overflow check as a range check is not
1744 -- performed in these cases.
1746 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
1747 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
1749 Reason := CE_Overflow_Check_Failed;
1751 Reason := CE_Range_Check_Failed;
1754 -- Raise CE if either conditions does not hold
1756 Insert_Action (Ck_Node,
1757 Make_Raise_Constraint_Error (Loc,
1758 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
1760 end Apply_Float_Conversion_Check;
1762 ------------------------
1763 -- Apply_Length_Check --
1764 ------------------------
1766 procedure Apply_Length_Check
1768 Target_Typ : Entity_Id;
1769 Source_Typ : Entity_Id := Empty)
1772 Apply_Selected_Length_Checks
1773 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1774 end Apply_Length_Check;
1776 ---------------------------
1777 -- Apply_Predicate_Check --
1778 ---------------------------
1780 procedure Apply_Predicate_Check (N : Node_Id; Typ : Entity_Id) is
1782 if Present (Predicate_Function (Typ)) then
1784 Make_Predicate_Check (Typ, Duplicate_Subexpr (N)));
1786 end Apply_Predicate_Check;
1788 -----------------------
1789 -- Apply_Range_Check --
1790 -----------------------
1792 procedure Apply_Range_Check
1794 Target_Typ : Entity_Id;
1795 Source_Typ : Entity_Id := Empty)
1798 Apply_Selected_Range_Checks
1799 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1800 end Apply_Range_Check;
1802 ------------------------------
1803 -- Apply_Scalar_Range_Check --
1804 ------------------------------
1806 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
1807 -- off if it is already set on.
1809 procedure Apply_Scalar_Range_Check
1811 Target_Typ : Entity_Id;
1812 Source_Typ : Entity_Id := Empty;
1813 Fixed_Int : Boolean := False)
1815 Parnt : constant Node_Id := Parent (Expr);
1817 Arr : Node_Id := Empty; -- initialize to prevent warning
1818 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
1821 Is_Subscr_Ref : Boolean;
1822 -- Set true if Expr is a subscript
1824 Is_Unconstrained_Subscr_Ref : Boolean;
1825 -- Set true if Expr is a subscript of an unconstrained array. In this
1826 -- case we do not attempt to do an analysis of the value against the
1827 -- range of the subscript, since we don't know the actual subtype.
1830 -- Set to True if Expr should be regarded as a real value even though
1831 -- the type of Expr might be discrete.
1833 procedure Bad_Value;
1834 -- Procedure called if value is determined to be out of range
1840 procedure Bad_Value is
1842 Apply_Compile_Time_Constraint_Error
1843 (Expr, "value not in range of}?", CE_Range_Check_Failed,
1848 -- Start of processing for Apply_Scalar_Range_Check
1851 -- Return if check obviously not needed
1854 -- Not needed inside generic
1858 -- Not needed if previous error
1860 or else Target_Typ = Any_Type
1861 or else Nkind (Expr) = N_Error
1863 -- Not needed for non-scalar type
1865 or else not Is_Scalar_Type (Target_Typ)
1867 -- Not needed if we know node raises CE already
1869 or else Raises_Constraint_Error (Expr)
1874 -- Now, see if checks are suppressed
1877 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
1879 if Is_Subscr_Ref then
1880 Arr := Prefix (Parnt);
1881 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
1883 if Is_Access_Type (Arr_Typ) then
1884 Arr_Typ := Designated_Type (Arr_Typ);
1888 if not Do_Range_Check (Expr) then
1890 -- Subscript reference. Check for Index_Checks suppressed
1892 if Is_Subscr_Ref then
1894 -- Check array type and its base type
1896 if Index_Checks_Suppressed (Arr_Typ)
1897 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
1901 -- Check array itself if it is an entity name
1903 elsif Is_Entity_Name (Arr)
1904 and then Index_Checks_Suppressed (Entity (Arr))
1908 -- Check expression itself if it is an entity name
1910 elsif Is_Entity_Name (Expr)
1911 and then Index_Checks_Suppressed (Entity (Expr))
1916 -- All other cases, check for Range_Checks suppressed
1919 -- Check target type and its base type
1921 if Range_Checks_Suppressed (Target_Typ)
1922 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
1926 -- Check expression itself if it is an entity name
1928 elsif Is_Entity_Name (Expr)
1929 and then Range_Checks_Suppressed (Entity (Expr))
1933 -- If Expr is part of an assignment statement, then check left
1934 -- side of assignment if it is an entity name.
1936 elsif Nkind (Parnt) = N_Assignment_Statement
1937 and then Is_Entity_Name (Name (Parnt))
1938 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
1945 -- Do not set range checks if they are killed
1947 if Nkind (Expr) = N_Unchecked_Type_Conversion
1948 and then Kill_Range_Check (Expr)
1953 -- Do not set range checks for any values from System.Scalar_Values
1954 -- since the whole idea of such values is to avoid checking them!
1956 if Is_Entity_Name (Expr)
1957 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
1962 -- Now see if we need a check
1964 if No (Source_Typ) then
1965 S_Typ := Etype (Expr);
1967 S_Typ := Source_Typ;
1970 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
1974 Is_Unconstrained_Subscr_Ref :=
1975 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
1977 -- Always do a range check if the source type includes infinities and
1978 -- the target type does not include infinities. We do not do this if
1979 -- range checks are killed.
1981 if Is_Floating_Point_Type (S_Typ)
1982 and then Has_Infinities (S_Typ)
1983 and then not Has_Infinities (Target_Typ)
1985 Enable_Range_Check (Expr);
1988 -- Return if we know expression is definitely in the range of the target
1989 -- type as determined by Determine_Range. Right now we only do this for
1990 -- discrete types, and not fixed-point or floating-point types.
1992 -- The additional less-precise tests below catch these cases
1994 -- Note: skip this if we are given a source_typ, since the point of
1995 -- supplying a Source_Typ is to stop us looking at the expression.
1996 -- We could sharpen this test to be out parameters only ???
1998 if Is_Discrete_Type (Target_Typ)
1999 and then Is_Discrete_Type (Etype (Expr))
2000 and then not Is_Unconstrained_Subscr_Ref
2001 and then No (Source_Typ)
2004 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
2005 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
2010 if Compile_Time_Known_Value (Tlo)
2011 and then Compile_Time_Known_Value (Thi)
2014 Lov : constant Uint := Expr_Value (Tlo);
2015 Hiv : constant Uint := Expr_Value (Thi);
2018 -- If range is null, we for sure have a constraint error
2019 -- (we don't even need to look at the value involved,
2020 -- since all possible values will raise CE).
2027 -- Otherwise determine range of value
2029 Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True);
2033 -- If definitely in range, all OK
2035 if Lo >= Lov and then Hi <= Hiv then
2038 -- If definitely not in range, warn
2040 elsif Lov > Hi or else Hiv < Lo then
2044 -- Otherwise we don't know
2056 Is_Floating_Point_Type (S_Typ)
2057 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
2059 -- Check if we can determine at compile time whether Expr is in the
2060 -- range of the target type. Note that if S_Typ is within the bounds
2061 -- of Target_Typ then this must be the case. This check is meaningful
2062 -- only if this is not a conversion between integer and real types.
2064 if not Is_Unconstrained_Subscr_Ref
2066 Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
2068 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
2070 Is_In_Range (Expr, Target_Typ,
2071 Assume_Valid => True,
2072 Fixed_Int => Fixed_Int,
2073 Int_Real => Int_Real))
2077 elsif Is_Out_Of_Range (Expr, Target_Typ,
2078 Assume_Valid => True,
2079 Fixed_Int => Fixed_Int,
2080 Int_Real => Int_Real)
2085 -- In the floating-point case, we only do range checks if the type is
2086 -- constrained. We definitely do NOT want range checks for unconstrained
2087 -- types, since we want to have infinities
2089 elsif Is_Floating_Point_Type (S_Typ) then
2090 if Is_Constrained (S_Typ) then
2091 Enable_Range_Check (Expr);
2094 -- For all other cases we enable a range check unconditionally
2097 Enable_Range_Check (Expr);
2100 end Apply_Scalar_Range_Check;
2102 ----------------------------------
2103 -- Apply_Selected_Length_Checks --
2104 ----------------------------------
2106 procedure Apply_Selected_Length_Checks
2108 Target_Typ : Entity_Id;
2109 Source_Typ : Entity_Id;
2110 Do_Static : Boolean)
2113 R_Result : Check_Result;
2116 Loc : constant Source_Ptr := Sloc (Ck_Node);
2117 Checks_On : constant Boolean :=
2118 (not Index_Checks_Suppressed (Target_Typ))
2120 (not Length_Checks_Suppressed (Target_Typ));
2123 if not Full_Expander_Active then
2128 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2130 for J in 1 .. 2 loop
2131 R_Cno := R_Result (J);
2132 exit when No (R_Cno);
2134 -- A length check may mention an Itype which is attached to a
2135 -- subsequent node. At the top level in a package this can cause
2136 -- an order-of-elaboration problem, so we make sure that the itype
2137 -- is referenced now.
2139 if Ekind (Current_Scope) = E_Package
2140 and then Is_Compilation_Unit (Current_Scope)
2142 Ensure_Defined (Target_Typ, Ck_Node);
2144 if Present (Source_Typ) then
2145 Ensure_Defined (Source_Typ, Ck_Node);
2147 elsif Is_Itype (Etype (Ck_Node)) then
2148 Ensure_Defined (Etype (Ck_Node), Ck_Node);
2152 -- If the item is a conditional raise of constraint error, then have
2153 -- a look at what check is being performed and ???
2155 if Nkind (R_Cno) = N_Raise_Constraint_Error
2156 and then Present (Condition (R_Cno))
2158 Cond := Condition (R_Cno);
2160 -- Case where node does not now have a dynamic check
2162 if not Has_Dynamic_Length_Check (Ck_Node) then
2164 -- If checks are on, just insert the check
2167 Insert_Action (Ck_Node, R_Cno);
2169 if not Do_Static then
2170 Set_Has_Dynamic_Length_Check (Ck_Node);
2173 -- If checks are off, then analyze the length check after
2174 -- temporarily attaching it to the tree in case the relevant
2175 -- condition can be evaluated at compile time. We still want a
2176 -- compile time warning in this case.
2179 Set_Parent (R_Cno, Ck_Node);
2184 -- Output a warning if the condition is known to be True
2186 if Is_Entity_Name (Cond)
2187 and then Entity (Cond) = Standard_True
2189 Apply_Compile_Time_Constraint_Error
2190 (Ck_Node, "wrong length for array of}?",
2191 CE_Length_Check_Failed,
2195 -- If we were only doing a static check, or if checks are not
2196 -- on, then we want to delete the check, since it is not needed.
2197 -- We do this by replacing the if statement by a null statement
2199 elsif Do_Static or else not Checks_On then
2200 Remove_Warning_Messages (R_Cno);
2201 Rewrite (R_Cno, Make_Null_Statement (Loc));
2205 Install_Static_Check (R_Cno, Loc);
2208 end Apply_Selected_Length_Checks;
2210 ---------------------------------
2211 -- Apply_Selected_Range_Checks --
2212 ---------------------------------
2214 procedure Apply_Selected_Range_Checks
2216 Target_Typ : Entity_Id;
2217 Source_Typ : Entity_Id;
2218 Do_Static : Boolean)
2221 R_Result : Check_Result;
2224 Loc : constant Source_Ptr := Sloc (Ck_Node);
2225 Checks_On : constant Boolean :=
2226 (not Index_Checks_Suppressed (Target_Typ))
2228 (not Range_Checks_Suppressed (Target_Typ));
2231 if not Full_Expander_Active or else not Checks_On then
2236 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2238 for J in 1 .. 2 loop
2240 R_Cno := R_Result (J);
2241 exit when No (R_Cno);
2243 -- If the item is a conditional raise of constraint error, then have
2244 -- a look at what check is being performed and ???
2246 if Nkind (R_Cno) = N_Raise_Constraint_Error
2247 and then Present (Condition (R_Cno))
2249 Cond := Condition (R_Cno);
2251 if not Has_Dynamic_Range_Check (Ck_Node) then
2252 Insert_Action (Ck_Node, R_Cno);
2254 if not Do_Static then
2255 Set_Has_Dynamic_Range_Check (Ck_Node);
2259 -- Output a warning if the condition is known to be True
2261 if Is_Entity_Name (Cond)
2262 and then Entity (Cond) = Standard_True
2264 -- Since an N_Range is technically not an expression, we have
2265 -- to set one of the bounds to C_E and then just flag the
2266 -- N_Range. The warning message will point to the lower bound
2267 -- and complain about a range, which seems OK.
2269 if Nkind (Ck_Node) = N_Range then
2270 Apply_Compile_Time_Constraint_Error
2271 (Low_Bound (Ck_Node), "static range out of bounds of}?",
2272 CE_Range_Check_Failed,
2276 Set_Raises_Constraint_Error (Ck_Node);
2279 Apply_Compile_Time_Constraint_Error
2280 (Ck_Node, "static value out of range of}?",
2281 CE_Range_Check_Failed,
2286 -- If we were only doing a static check, or if checks are not
2287 -- on, then we want to delete the check, since it is not needed.
2288 -- We do this by replacing the if statement by a null statement
2290 elsif Do_Static or else not Checks_On then
2291 Remove_Warning_Messages (R_Cno);
2292 Rewrite (R_Cno, Make_Null_Statement (Loc));
2296 Install_Static_Check (R_Cno, Loc);
2299 end Apply_Selected_Range_Checks;
2301 -------------------------------
2302 -- Apply_Static_Length_Check --
2303 -------------------------------
2305 procedure Apply_Static_Length_Check
2307 Target_Typ : Entity_Id;
2308 Source_Typ : Entity_Id := Empty)
2311 Apply_Selected_Length_Checks
2312 (Expr, Target_Typ, Source_Typ, Do_Static => True);
2313 end Apply_Static_Length_Check;
2315 -------------------------------------
2316 -- Apply_Subscript_Validity_Checks --
2317 -------------------------------------
2319 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
2323 pragma Assert (Nkind (Expr) = N_Indexed_Component);
2325 -- Loop through subscripts
2327 Sub := First (Expressions (Expr));
2328 while Present (Sub) loop
2330 -- Check one subscript. Note that we do not worry about enumeration
2331 -- type with holes, since we will convert the value to a Pos value
2332 -- for the subscript, and that convert will do the necessary validity
2335 Ensure_Valid (Sub, Holes_OK => True);
2337 -- Move to next subscript
2341 end Apply_Subscript_Validity_Checks;
2343 ----------------------------------
2344 -- Apply_Type_Conversion_Checks --
2345 ----------------------------------
2347 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
2348 Target_Type : constant Entity_Id := Etype (N);
2349 Target_Base : constant Entity_Id := Base_Type (Target_Type);
2350 Expr : constant Node_Id := Expression (N);
2352 Expr_Type : constant Entity_Id := Underlying_Type (Etype (Expr));
2353 -- Note: if Etype (Expr) is a private type without discriminants, its
2354 -- full view might have discriminants with defaults, so we need the
2355 -- full view here to retrieve the constraints.
2358 if Inside_A_Generic then
2361 -- Skip these checks if serious errors detected, there are some nasty
2362 -- situations of incomplete trees that blow things up.
2364 elsif Serious_Errors_Detected > 0 then
2367 -- Scalar type conversions of the form Target_Type (Expr) require a
2368 -- range check if we cannot be sure that Expr is in the base type of
2369 -- Target_Typ and also that Expr is in the range of Target_Typ. These
2370 -- are not quite the same condition from an implementation point of
2371 -- view, but clearly the second includes the first.
2373 elsif Is_Scalar_Type (Target_Type) then
2375 Conv_OK : constant Boolean := Conversion_OK (N);
2376 -- If the Conversion_OK flag on the type conversion is set and no
2377 -- floating point type is involved in the type conversion then
2378 -- fixed point values must be read as integral values.
2380 Float_To_Int : constant Boolean :=
2381 Is_Floating_Point_Type (Expr_Type)
2382 and then Is_Integer_Type (Target_Type);
2385 if not Overflow_Checks_Suppressed (Target_Base)
2387 In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK)
2388 and then not Float_To_Int
2390 Activate_Overflow_Check (N);
2393 if not Range_Checks_Suppressed (Target_Type)
2394 and then not Range_Checks_Suppressed (Expr_Type)
2396 if Float_To_Int then
2397 Apply_Float_Conversion_Check (Expr, Target_Type);
2399 Apply_Scalar_Range_Check
2400 (Expr, Target_Type, Fixed_Int => Conv_OK);
2402 -- If the target type has predicates, we need to indicate
2403 -- the need for a check, even if Determine_Range finds
2404 -- that the value is within bounds. This may be the case
2405 -- e.g for a division with a constant denominator.
2407 if Has_Predicates (Target_Type) then
2408 Enable_Range_Check (Expr);
2414 elsif Comes_From_Source (N)
2415 and then not Discriminant_Checks_Suppressed (Target_Type)
2416 and then Is_Record_Type (Target_Type)
2417 and then Is_Derived_Type (Target_Type)
2418 and then not Is_Tagged_Type (Target_Type)
2419 and then not Is_Constrained (Target_Type)
2420 and then Present (Stored_Constraint (Target_Type))
2422 -- An unconstrained derived type may have inherited discriminant.
2423 -- Build an actual discriminant constraint list using the stored
2424 -- constraint, to verify that the expression of the parent type
2425 -- satisfies the constraints imposed by the (unconstrained!)
2426 -- derived type. This applies to value conversions, not to view
2427 -- conversions of tagged types.
2430 Loc : constant Source_Ptr := Sloc (N);
2432 Constraint : Elmt_Id;
2433 Discr_Value : Node_Id;
2436 New_Constraints : constant Elist_Id := New_Elmt_List;
2437 Old_Constraints : constant Elist_Id :=
2438 Discriminant_Constraint (Expr_Type);
2441 Constraint := First_Elmt (Stored_Constraint (Target_Type));
2442 while Present (Constraint) loop
2443 Discr_Value := Node (Constraint);
2445 if Is_Entity_Name (Discr_Value)
2446 and then Ekind (Entity (Discr_Value)) = E_Discriminant
2448 Discr := Corresponding_Discriminant (Entity (Discr_Value));
2451 and then Scope (Discr) = Base_Type (Expr_Type)
2453 -- Parent is constrained by new discriminant. Obtain
2454 -- Value of original discriminant in expression. If the
2455 -- new discriminant has been used to constrain more than
2456 -- one of the stored discriminants, this will provide the
2457 -- required consistency check.
2460 (Make_Selected_Component (Loc,
2462 Duplicate_Subexpr_No_Checks
2463 (Expr, Name_Req => True),
2465 Make_Identifier (Loc, Chars (Discr))),
2469 -- Discriminant of more remote ancestor ???
2474 -- Derived type definition has an explicit value for this
2475 -- stored discriminant.
2479 (Duplicate_Subexpr_No_Checks (Discr_Value),
2483 Next_Elmt (Constraint);
2486 -- Use the unconstrained expression type to retrieve the
2487 -- discriminants of the parent, and apply momentarily the
2488 -- discriminant constraint synthesized above.
2490 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
2491 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
2492 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
2495 Make_Raise_Constraint_Error (Loc,
2497 Reason => CE_Discriminant_Check_Failed));
2500 -- For arrays, conversions are applied during expansion, to take into
2501 -- accounts changes of representation. The checks become range checks on
2502 -- the base type or length checks on the subtype, depending on whether
2503 -- the target type is unconstrained or constrained.
2508 end Apply_Type_Conversion_Checks;
2510 ----------------------------------------------
2511 -- Apply_Universal_Integer_Attribute_Checks --
2512 ----------------------------------------------
2514 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
2515 Loc : constant Source_Ptr := Sloc (N);
2516 Typ : constant Entity_Id := Etype (N);
2519 if Inside_A_Generic then
2522 -- Nothing to do if checks are suppressed
2524 elsif Range_Checks_Suppressed (Typ)
2525 and then Overflow_Checks_Suppressed (Typ)
2529 -- Nothing to do if the attribute does not come from source. The
2530 -- internal attributes we generate of this type do not need checks,
2531 -- and furthermore the attempt to check them causes some circular
2532 -- elaboration orders when dealing with packed types.
2534 elsif not Comes_From_Source (N) then
2537 -- If the prefix is a selected component that depends on a discriminant
2538 -- the check may improperly expose a discriminant instead of using
2539 -- the bounds of the object itself. Set the type of the attribute to
2540 -- the base type of the context, so that a check will be imposed when
2541 -- needed (e.g. if the node appears as an index).
2543 elsif Nkind (Prefix (N)) = N_Selected_Component
2544 and then Ekind (Typ) = E_Signed_Integer_Subtype
2545 and then Depends_On_Discriminant (Scalar_Range (Typ))
2547 Set_Etype (N, Base_Type (Typ));
2549 -- Otherwise, replace the attribute node with a type conversion node
2550 -- whose expression is the attribute, retyped to universal integer, and
2551 -- whose subtype mark is the target type. The call to analyze this
2552 -- conversion will set range and overflow checks as required for proper
2553 -- detection of an out of range value.
2556 Set_Etype (N, Universal_Integer);
2557 Set_Analyzed (N, True);
2560 Make_Type_Conversion (Loc,
2561 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
2562 Expression => Relocate_Node (N)));
2564 Analyze_And_Resolve (N, Typ);
2567 end Apply_Universal_Integer_Attribute_Checks;
2569 -------------------------------------
2570 -- Atomic_Synchronization_Disabled --
2571 -------------------------------------
2573 -- Note: internally Disable/Enable_Atomic_Synchronization is implemented
2574 -- using a bogus check called Atomic_Synchronization. This is to make it
2575 -- more convenient to get exactly the same semantics as [Un]Suppress.
2577 function Atomic_Synchronization_Disabled (E : Entity_Id) return Boolean is
2579 -- If debug flag d.e is set, always return False, i.e. all atomic sync
2580 -- looks enabled, since it is never disabled.
2582 if Debug_Flag_Dot_E then
2585 -- If debug flag d.d is set then always return True, i.e. all atomic
2586 -- sync looks disabled, since it always tests True.
2588 elsif Debug_Flag_Dot_D then
2591 -- If entity present, then check result for that entity
2593 elsif Present (E) and then Checks_May_Be_Suppressed (E) then
2594 return Is_Check_Suppressed (E, Atomic_Synchronization);
2596 -- Otherwise result depends on current scope setting
2599 return Scope_Suppress (Atomic_Synchronization);
2601 end Atomic_Synchronization_Disabled;
2603 -------------------------------
2604 -- Build_Discriminant_Checks --
2605 -------------------------------
2607 function Build_Discriminant_Checks
2609 T_Typ : Entity_Id) return Node_Id
2611 Loc : constant Source_Ptr := Sloc (N);
2614 Disc_Ent : Entity_Id;
2618 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
2620 ----------------------------------
2621 -- Aggregate_Discriminant_Value --
2622 ----------------------------------
2624 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
2628 -- The aggregate has been normalized with named associations. We use
2629 -- the Chars field to locate the discriminant to take into account
2630 -- discriminants in derived types, which carry the same name as those
2633 Assoc := First (Component_Associations (N));
2634 while Present (Assoc) loop
2635 if Chars (First (Choices (Assoc))) = Chars (Disc) then
2636 return Expression (Assoc);
2642 -- Discriminant must have been found in the loop above
2644 raise Program_Error;
2645 end Aggregate_Discriminant_Val;
2647 -- Start of processing for Build_Discriminant_Checks
2650 -- Loop through discriminants evolving the condition
2653 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
2655 -- For a fully private type, use the discriminants of the parent type
2657 if Is_Private_Type (T_Typ)
2658 and then No (Full_View (T_Typ))
2660 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
2662 Disc_Ent := First_Discriminant (T_Typ);
2665 while Present (Disc) loop
2666 Dval := Node (Disc);
2668 if Nkind (Dval) = N_Identifier
2669 and then Ekind (Entity (Dval)) = E_Discriminant
2671 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
2673 Dval := Duplicate_Subexpr_No_Checks (Dval);
2676 -- If we have an Unchecked_Union node, we can infer the discriminants
2679 if Is_Unchecked_Union (Base_Type (T_Typ)) then
2681 Get_Discriminant_Value (
2682 First_Discriminant (T_Typ),
2684 Stored_Constraint (T_Typ)));
2686 elsif Nkind (N) = N_Aggregate then
2688 Duplicate_Subexpr_No_Checks
2689 (Aggregate_Discriminant_Val (Disc_Ent));
2693 Make_Selected_Component (Loc,
2695 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
2697 Make_Identifier (Loc, Chars (Disc_Ent)));
2699 Set_Is_In_Discriminant_Check (Dref);
2702 Evolve_Or_Else (Cond,
2705 Right_Opnd => Dval));
2708 Next_Discriminant (Disc_Ent);
2712 end Build_Discriminant_Checks;
2718 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
2726 -- Always check if not simple entity
2728 if Nkind (Nod) not in N_Has_Entity
2729 or else not Comes_From_Source (Nod)
2734 -- Look up tree for short circuit
2741 -- Done if out of subexpression (note that we allow generated stuff
2742 -- such as itype declarations in this context, to keep the loop going
2743 -- since we may well have generated such stuff in complex situations.
2744 -- Also done if no parent (probably an error condition, but no point
2745 -- in behaving nasty if we find it!)
2748 or else (K not in N_Subexpr and then Comes_From_Source (P))
2752 -- Or/Or Else case, where test is part of the right operand, or is
2753 -- part of one of the actions associated with the right operand, and
2754 -- the left operand is an equality test.
2756 elsif K = N_Op_Or then
2757 exit when N = Right_Opnd (P)
2758 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2760 elsif K = N_Or_Else then
2761 exit when (N = Right_Opnd (P)
2764 and then List_Containing (N) = Actions (P)))
2765 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2767 -- Similar test for the And/And then case, where the left operand
2768 -- is an inequality test.
2770 elsif K = N_Op_And then
2771 exit when N = Right_Opnd (P)
2772 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2774 elsif K = N_And_Then then
2775 exit when (N = Right_Opnd (P)
2778 and then List_Containing (N) = Actions (P)))
2779 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2785 -- If we fall through the loop, then we have a conditional with an
2786 -- appropriate test as its left operand. So test further.
2789 R := Right_Opnd (L);
2792 -- Left operand of test must match original variable
2794 if Nkind (L) not in N_Has_Entity
2795 or else Entity (L) /= Entity (Nod)
2800 -- Right operand of test must be key value (zero or null)
2803 when Access_Check =>
2804 if not Known_Null (R) then
2808 when Division_Check =>
2809 if not Compile_Time_Known_Value (R)
2810 or else Expr_Value (R) /= Uint_0
2816 raise Program_Error;
2819 -- Here we have the optimizable case, warn if not short-circuited
2821 if K = N_Op_And or else K = N_Op_Or then
2823 when Access_Check =>
2825 ("Constraint_Error may be raised (access check)?",
2827 when Division_Check =>
2829 ("Constraint_Error may be raised (zero divide)?",
2833 raise Program_Error;
2836 if K = N_Op_And then
2837 Error_Msg_N -- CODEFIX
2838 ("use `AND THEN` instead of AND?", P);
2840 Error_Msg_N -- CODEFIX
2841 ("use `OR ELSE` instead of OR?", P);
2844 -- If not short-circuited, we need the check
2848 -- If short-circuited, we can omit the check
2855 -----------------------------------
2856 -- Check_Valid_Lvalue_Subscripts --
2857 -----------------------------------
2859 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
2861 -- Skip this if range checks are suppressed
2863 if Range_Checks_Suppressed (Etype (Expr)) then
2866 -- Only do this check for expressions that come from source. We assume
2867 -- that expander generated assignments explicitly include any necessary
2868 -- checks. Note that this is not just an optimization, it avoids
2869 -- infinite recursions!
2871 elsif not Comes_From_Source (Expr) then
2874 -- For a selected component, check the prefix
2876 elsif Nkind (Expr) = N_Selected_Component then
2877 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2880 -- Case of indexed component
2882 elsif Nkind (Expr) = N_Indexed_Component then
2883 Apply_Subscript_Validity_Checks (Expr);
2885 -- Prefix may itself be or contain an indexed component, and these
2886 -- subscripts need checking as well.
2888 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2890 end Check_Valid_Lvalue_Subscripts;
2892 ----------------------------------
2893 -- Null_Exclusion_Static_Checks --
2894 ----------------------------------
2896 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
2897 Error_Node : Node_Id;
2899 Has_Null : constant Boolean := Has_Null_Exclusion (N);
2900 K : constant Node_Kind := Nkind (N);
2905 (K = N_Component_Declaration
2906 or else K = N_Discriminant_Specification
2907 or else K = N_Function_Specification
2908 or else K = N_Object_Declaration
2909 or else K = N_Parameter_Specification);
2911 if K = N_Function_Specification then
2912 Typ := Etype (Defining_Entity (N));
2914 Typ := Etype (Defining_Identifier (N));
2918 when N_Component_Declaration =>
2919 if Present (Access_Definition (Component_Definition (N))) then
2920 Error_Node := Component_Definition (N);
2922 Error_Node := Subtype_Indication (Component_Definition (N));
2925 when N_Discriminant_Specification =>
2926 Error_Node := Discriminant_Type (N);
2928 when N_Function_Specification =>
2929 Error_Node := Result_Definition (N);
2931 when N_Object_Declaration =>
2932 Error_Node := Object_Definition (N);
2934 when N_Parameter_Specification =>
2935 Error_Node := Parameter_Type (N);
2938 raise Program_Error;
2943 -- Enforce legality rule 3.10 (13): A null exclusion can only be
2944 -- applied to an access [sub]type.
2946 if not Is_Access_Type (Typ) then
2948 ("`NOT NULL` allowed only for an access type", Error_Node);
2950 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
2951 -- be applied to a [sub]type that does not exclude null already.
2953 elsif Can_Never_Be_Null (Typ)
2954 and then Comes_From_Source (Typ)
2957 ("`NOT NULL` not allowed (& already excludes null)",
2962 -- Check that null-excluding objects are always initialized, except for
2963 -- deferred constants, for which the expression will appear in the full
2966 if K = N_Object_Declaration
2967 and then No (Expression (N))
2968 and then not Constant_Present (N)
2969 and then not No_Initialization (N)
2971 -- Add an expression that assigns null. This node is needed by
2972 -- Apply_Compile_Time_Constraint_Error, which will replace this with
2973 -- a Constraint_Error node.
2975 Set_Expression (N, Make_Null (Sloc (N)));
2976 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
2978 Apply_Compile_Time_Constraint_Error
2979 (N => Expression (N),
2980 Msg => "(Ada 2005) null-excluding objects must be initialized?",
2981 Reason => CE_Null_Not_Allowed);
2984 -- Check that a null-excluding component, formal or object is not being
2985 -- assigned a null value. Otherwise generate a warning message and
2986 -- replace Expression (N) by an N_Constraint_Error node.
2988 if K /= N_Function_Specification then
2989 Expr := Expression (N);
2991 if Present (Expr) and then Known_Null (Expr) then
2993 when N_Component_Declaration |
2994 N_Discriminant_Specification =>
2995 Apply_Compile_Time_Constraint_Error
2997 Msg => "(Ada 2005) null not allowed " &
2998 "in null-excluding components?",
2999 Reason => CE_Null_Not_Allowed);
3001 when N_Object_Declaration =>
3002 Apply_Compile_Time_Constraint_Error
3004 Msg => "(Ada 2005) null not allowed " &
3005 "in null-excluding objects?",
3006 Reason => CE_Null_Not_Allowed);
3008 when N_Parameter_Specification =>
3009 Apply_Compile_Time_Constraint_Error
3011 Msg => "(Ada 2005) null not allowed " &
3012 "in null-excluding formals?",
3013 Reason => CE_Null_Not_Allowed);
3020 end Null_Exclusion_Static_Checks;
3022 ----------------------------------
3023 -- Conditional_Statements_Begin --
3024 ----------------------------------
3026 procedure Conditional_Statements_Begin is
3028 Saved_Checks_TOS := Saved_Checks_TOS + 1;
3030 -- If stack overflows, kill all checks, that way we know to simply reset
3031 -- the number of saved checks to zero on return. This should never occur
3034 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
3037 -- In the normal case, we just make a new stack entry saving the current
3038 -- number of saved checks for a later restore.
3041 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
3043 if Debug_Flag_CC then
3044 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
3048 end Conditional_Statements_Begin;
3050 --------------------------------
3051 -- Conditional_Statements_End --
3052 --------------------------------
3054 procedure Conditional_Statements_End is
3056 pragma Assert (Saved_Checks_TOS > 0);
3058 -- If the saved checks stack overflowed, then we killed all checks, so
3059 -- setting the number of saved checks back to zero is correct. This
3060 -- should never occur in practice.
3062 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
3063 Num_Saved_Checks := 0;
3065 -- In the normal case, restore the number of saved checks from the top
3069 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
3070 if Debug_Flag_CC then
3071 w ("Conditional_Statements_End: Num_Saved_Checks = ",
3076 Saved_Checks_TOS := Saved_Checks_TOS - 1;
3077 end Conditional_Statements_End;
3079 ---------------------
3080 -- Determine_Range --
3081 ---------------------
3083 Cache_Size : constant := 2 ** 10;
3084 type Cache_Index is range 0 .. Cache_Size - 1;
3085 -- Determine size of below cache (power of 2 is more efficient!)
3087 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
3088 Determine_Range_Cache_V : array (Cache_Index) of Boolean;
3089 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
3090 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
3091 -- The above arrays are used to implement a small direct cache for
3092 -- Determine_Range calls. Because of the way Determine_Range recursively
3093 -- traces subexpressions, and because overflow checking calls the routine
3094 -- on the way up the tree, a quadratic behavior can otherwise be
3095 -- encountered in large expressions. The cache entry for node N is stored
3096 -- in the (N mod Cache_Size) entry, and can be validated by checking the
3097 -- actual node value stored there. The Range_Cache_V array records the
3098 -- setting of Assume_Valid for the cache entry.
3100 procedure Determine_Range
3105 Assume_Valid : Boolean := False)
3107 Typ : Entity_Id := Etype (N);
3108 -- Type to use, may get reset to base type for possibly invalid entity
3112 -- Lo and Hi bounds of left operand
3116 -- Lo and Hi bounds of right (or only) operand
3119 -- Temp variable used to hold a bound node
3122 -- High bound of base type of expression
3126 -- Refined values for low and high bounds, after tightening
3129 -- Used in lower level calls to indicate if call succeeded
3131 Cindex : Cache_Index;
3132 -- Used to search cache
3134 function OK_Operands return Boolean;
3135 -- Used for binary operators. Determines the ranges of the left and
3136 -- right operands, and if they are both OK, returns True, and puts
3137 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
3143 function OK_Operands return Boolean is
3146 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
3153 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3157 -- Start of processing for Determine_Range
3160 -- For temporary constants internally generated to remove side effects
3161 -- we must use the corresponding expression to determine the range of
3164 if Is_Entity_Name (N)
3165 and then Nkind (Parent (Entity (N))) = N_Object_Declaration
3166 and then Ekind (Entity (N)) = E_Constant
3167 and then Is_Internal_Name (Chars (Entity (N)))
3170 (Expression (Parent (Entity (N))), OK, Lo, Hi, Assume_Valid);
3174 -- Prevent junk warnings by initializing range variables
3181 -- If type is not defined, we can't determine its range
3185 -- We don't deal with anything except discrete types
3187 or else not Is_Discrete_Type (Typ)
3189 -- Ignore type for which an error has been posted, since range in
3190 -- this case may well be a bogosity deriving from the error. Also
3191 -- ignore if error posted on the reference node.
3193 or else Error_Posted (N) or else Error_Posted (Typ)
3199 -- For all other cases, we can determine the range
3203 -- If value is compile time known, then the possible range is the one
3204 -- value that we know this expression definitely has!
3206 if Compile_Time_Known_Value (N) then
3207 Lo := Expr_Value (N);
3212 -- Return if already in the cache
3214 Cindex := Cache_Index (N mod Cache_Size);
3216 if Determine_Range_Cache_N (Cindex) = N
3218 Determine_Range_Cache_V (Cindex) = Assume_Valid
3220 Lo := Determine_Range_Cache_Lo (Cindex);
3221 Hi := Determine_Range_Cache_Hi (Cindex);
3225 -- Otherwise, start by finding the bounds of the type of the expression,
3226 -- the value cannot be outside this range (if it is, then we have an
3227 -- overflow situation, which is a separate check, we are talking here
3228 -- only about the expression value).
3230 -- First a check, never try to find the bounds of a generic type, since
3231 -- these bounds are always junk values, and it is only valid to look at
3232 -- the bounds in an instance.
3234 if Is_Generic_Type (Typ) then
3239 -- First step, change to use base type unless we know the value is valid
3241 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
3242 or else Assume_No_Invalid_Values
3243 or else Assume_Valid
3247 Typ := Underlying_Type (Base_Type (Typ));
3250 -- We use the actual bound unless it is dynamic, in which case use the
3251 -- corresponding base type bound if possible. If we can't get a bound
3252 -- then we figure we can't determine the range (a peculiar case, that
3253 -- perhaps cannot happen, but there is no point in bombing in this
3254 -- optimization circuit.
3256 -- First the low bound
3258 Bound := Type_Low_Bound (Typ);
3260 if Compile_Time_Known_Value (Bound) then
3261 Lo := Expr_Value (Bound);
3263 elsif Compile_Time_Known_Value (Type_Low_Bound (Base_Type (Typ))) then
3264 Lo := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
3271 -- Now the high bound
3273 Bound := Type_High_Bound (Typ);
3275 -- We need the high bound of the base type later on, and this should
3276 -- always be compile time known. Again, it is not clear that this
3277 -- can ever be false, but no point in bombing.
3279 if Compile_Time_Known_Value (Type_High_Bound (Base_Type (Typ))) then
3280 Hbound := Expr_Value (Type_High_Bound (Base_Type (Typ)));
3288 -- If we have a static subtype, then that may have a tighter bound so
3289 -- use the upper bound of the subtype instead in this case.
3291 if Compile_Time_Known_Value (Bound) then
3292 Hi := Expr_Value (Bound);
3295 -- We may be able to refine this value in certain situations. If any
3296 -- refinement is possible, then Lor and Hir are set to possibly tighter
3297 -- bounds, and OK1 is set to True.
3301 -- For unary plus, result is limited by range of operand
3305 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
3307 -- For unary minus, determine range of operand, and negate it
3311 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3318 -- For binary addition, get range of each operand and do the
3319 -- addition to get the result range.
3323 Lor := Lo_Left + Lo_Right;
3324 Hir := Hi_Left + Hi_Right;
3327 -- Division is tricky. The only case we consider is where the right
3328 -- operand is a positive constant, and in this case we simply divide
3329 -- the bounds of the left operand
3333 if Lo_Right = Hi_Right
3334 and then Lo_Right > 0
3336 Lor := Lo_Left / Lo_Right;
3337 Hir := Hi_Left / Lo_Right;
3344 -- For binary subtraction, get range of each operand and do the worst
3345 -- case subtraction to get the result range.
3347 when N_Op_Subtract =>
3349 Lor := Lo_Left - Hi_Right;
3350 Hir := Hi_Left - Lo_Right;
3353 -- For MOD, if right operand is a positive constant, then result must
3354 -- be in the allowable range of mod results.
3358 if Lo_Right = Hi_Right
3359 and then Lo_Right /= 0
3361 if Lo_Right > 0 then
3363 Hir := Lo_Right - 1;
3365 else -- Lo_Right < 0
3366 Lor := Lo_Right + 1;
3375 -- For REM, if right operand is a positive constant, then result must
3376 -- be in the allowable range of mod results.
3380 if Lo_Right = Hi_Right
3381 and then Lo_Right /= 0
3384 Dval : constant Uint := (abs Lo_Right) - 1;
3387 -- The sign of the result depends on the sign of the
3388 -- dividend (but not on the sign of the divisor, hence
3389 -- the abs operation above).
3409 -- Attribute reference cases
3411 when N_Attribute_Reference =>
3412 case Attribute_Name (N) is
3414 -- For Pos/Val attributes, we can refine the range using the
3415 -- possible range of values of the attribute expression.
3417 when Name_Pos | Name_Val =>
3419 (First (Expressions (N)), OK1, Lor, Hir, Assume_Valid);
3421 -- For Length attribute, use the bounds of the corresponding
3422 -- index type to refine the range.
3426 Atyp : Entity_Id := Etype (Prefix (N));
3434 if Is_Access_Type (Atyp) then
3435 Atyp := Designated_Type (Atyp);
3438 -- For string literal, we know exact value
3440 if Ekind (Atyp) = E_String_Literal_Subtype then
3442 Lo := String_Literal_Length (Atyp);
3443 Hi := String_Literal_Length (Atyp);
3447 -- Otherwise check for expression given
3449 if No (Expressions (N)) then
3453 UI_To_Int (Expr_Value (First (Expressions (N))));
3456 Indx := First_Index (Atyp);
3457 for J in 2 .. Inum loop
3458 Indx := Next_Index (Indx);
3461 -- If the index type is a formal type or derived from
3462 -- one, the bounds are not static.
3464 if Is_Generic_Type (Root_Type (Etype (Indx))) then
3470 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU,
3475 (Type_High_Bound (Etype (Indx)), OK1, UL, UU,
3480 -- The maximum value for Length is the biggest
3481 -- possible gap between the values of the bounds.
3482 -- But of course, this value cannot be negative.
3484 Hir := UI_Max (Uint_0, UU - LL + 1);
3486 -- For constrained arrays, the minimum value for
3487 -- Length is taken from the actual value of the
3488 -- bounds, since the index will be exactly of this
3491 if Is_Constrained (Atyp) then
3492 Lor := UI_Max (Uint_0, UL - LU + 1);
3494 -- For an unconstrained array, the minimum value
3495 -- for length is always zero.
3504 -- No special handling for other attributes
3505 -- Probably more opportunities exist here???
3512 -- For type conversion from one discrete type to another, we can
3513 -- refine the range using the converted value.
3515 when N_Type_Conversion =>
3516 Determine_Range (Expression (N), OK1, Lor, Hir, Assume_Valid);
3518 -- Nothing special to do for all other expression kinds
3526 -- At this stage, if OK1 is true, then we know that the actual result of
3527 -- the computed expression is in the range Lor .. Hir. We can use this
3528 -- to restrict the possible range of results.
3530 -- If one of the computed bounds is outside the range of the base type,
3531 -- the expression may raise an exception and we had better indicate that
3532 -- the evaluation has failed, at least if checks are enabled.
3535 and then Enable_Overflow_Checks
3536 and then not Is_Entity_Name (N)
3537 and then (Lor < Lo or else Hir > Hi)
3545 -- If the refined value of the low bound is greater than the type
3546 -- high bound, then reset it to the more restrictive value. However,
3547 -- we do NOT do this for the case of a modular type where the
3548 -- possible upper bound on the value is above the base type high
3549 -- bound, because that means the result could wrap.
3552 and then not (Is_Modular_Integer_Type (Typ) and then Hir > Hbound)
3557 -- Similarly, if the refined value of the high bound is less than the
3558 -- value so far, then reset it to the more restrictive value. Again,
3559 -- we do not do this if the refined low bound is negative for a
3560 -- modular type, since this would wrap.
3563 and then not (Is_Modular_Integer_Type (Typ) and then Lor < Uint_0)
3569 -- Set cache entry for future call and we are all done
3571 Determine_Range_Cache_N (Cindex) := N;
3572 Determine_Range_Cache_V (Cindex) := Assume_Valid;
3573 Determine_Range_Cache_Lo (Cindex) := Lo;
3574 Determine_Range_Cache_Hi (Cindex) := Hi;
3577 -- If any exception occurs, it means that we have some bug in the compiler,
3578 -- possibly triggered by a previous error, or by some unforeseen peculiar
3579 -- occurrence. However, this is only an optimization attempt, so there is
3580 -- really no point in crashing the compiler. Instead we just decide, too
3581 -- bad, we can't figure out a range in this case after all.
3586 -- Debug flag K disables this behavior (useful for debugging)
3588 if Debug_Flag_K then
3596 end Determine_Range;
3598 ------------------------------------
3599 -- Discriminant_Checks_Suppressed --
3600 ------------------------------------
3602 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
3605 if Is_Unchecked_Union (E) then
3607 elsif Checks_May_Be_Suppressed (E) then
3608 return Is_Check_Suppressed (E, Discriminant_Check);
3612 return Scope_Suppress (Discriminant_Check);
3613 end Discriminant_Checks_Suppressed;
3615 --------------------------------
3616 -- Division_Checks_Suppressed --
3617 --------------------------------
3619 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
3621 if Present (E) and then Checks_May_Be_Suppressed (E) then
3622 return Is_Check_Suppressed (E, Division_Check);
3624 return Scope_Suppress (Division_Check);
3626 end Division_Checks_Suppressed;
3628 -----------------------------------
3629 -- Elaboration_Checks_Suppressed --
3630 -----------------------------------
3632 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
3634 -- The complication in this routine is that if we are in the dynamic
3635 -- model of elaboration, we also check All_Checks, since All_Checks
3636 -- does not set Elaboration_Check explicitly.
3639 if Kill_Elaboration_Checks (E) then
3642 elsif Checks_May_Be_Suppressed (E) then
3643 if Is_Check_Suppressed (E, Elaboration_Check) then
3645 elsif Dynamic_Elaboration_Checks then
3646 return Is_Check_Suppressed (E, All_Checks);
3653 if Scope_Suppress (Elaboration_Check) then
3655 elsif Dynamic_Elaboration_Checks then
3656 return Scope_Suppress (All_Checks);
3660 end Elaboration_Checks_Suppressed;
3662 ---------------------------
3663 -- Enable_Overflow_Check --
3664 ---------------------------
3666 procedure Enable_Overflow_Check (N : Node_Id) is
3667 Typ : constant Entity_Id := Base_Type (Etype (N));
3676 if Debug_Flag_CC then
3677 w ("Enable_Overflow_Check for node ", Int (N));
3678 Write_Str (" Source location = ");
3683 -- No check if overflow checks suppressed for type of node
3685 if Present (Etype (N))
3686 and then Overflow_Checks_Suppressed (Etype (N))
3690 -- Nothing to do for unsigned integer types, which do not overflow
3692 elsif Is_Modular_Integer_Type (Typ) then
3695 -- Nothing to do if the range of the result is known OK. We skip this
3696 -- for conversions, since the caller already did the check, and in any
3697 -- case the condition for deleting the check for a type conversion is
3700 elsif Nkind (N) /= N_Type_Conversion then
3701 Determine_Range (N, OK, Lo, Hi, Assume_Valid => True);
3703 -- Note in the test below that we assume that the range is not OK
3704 -- if a bound of the range is equal to that of the type. That's not
3705 -- quite accurate but we do this for the following reasons:
3707 -- a) The way that Determine_Range works, it will typically report
3708 -- the bounds of the value as being equal to the bounds of the
3709 -- type, because it either can't tell anything more precise, or
3710 -- does not think it is worth the effort to be more precise.
3712 -- b) It is very unusual to have a situation in which this would
3713 -- generate an unnecessary overflow check (an example would be
3714 -- a subtype with a range 0 .. Integer'Last - 1 to which the
3715 -- literal value one is added).
3717 -- c) The alternative is a lot of special casing in this routine
3718 -- which would partially duplicate Determine_Range processing.
3721 and then Lo > Expr_Value (Type_Low_Bound (Typ))
3722 and then Hi < Expr_Value (Type_High_Bound (Typ))
3724 if Debug_Flag_CC then
3725 w ("No overflow check required");
3732 -- If not in optimizing mode, set flag and we are done. We are also done
3733 -- (and just set the flag) if the type is not a discrete type, since it
3734 -- is not worth the effort to eliminate checks for other than discrete
3735 -- types. In addition, we take this same path if we have stored the
3736 -- maximum number of checks possible already (a very unlikely situation,
3737 -- but we do not want to blow up!)
3739 if Optimization_Level = 0
3740 or else not Is_Discrete_Type (Etype (N))
3741 or else Num_Saved_Checks = Saved_Checks'Last
3743 Activate_Overflow_Check (N);
3745 if Debug_Flag_CC then
3746 w ("Optimization off");
3752 -- Otherwise evaluate and check the expression
3757 Target_Type => Empty,
3763 if Debug_Flag_CC then
3764 w ("Called Find_Check");
3768 w (" Check_Num = ", Chk);
3769 w (" Ent = ", Int (Ent));
3770 Write_Str (" Ofs = ");
3775 -- If check is not of form to optimize, then set flag and we are done
3778 Activate_Overflow_Check (N);
3782 -- If check is already performed, then return without setting flag
3785 if Debug_Flag_CC then
3786 w ("Check suppressed!");
3792 -- Here we will make a new entry for the new check
3794 Activate_Overflow_Check (N);
3795 Num_Saved_Checks := Num_Saved_Checks + 1;
3796 Saved_Checks (Num_Saved_Checks) :=
3801 Target_Type => Empty);
3803 if Debug_Flag_CC then
3804 w ("Make new entry, check number = ", Num_Saved_Checks);
3805 w (" Entity = ", Int (Ent));
3806 Write_Str (" Offset = ");
3808 w (" Check_Type = O");
3809 w (" Target_Type = Empty");
3812 -- If we get an exception, then something went wrong, probably because of
3813 -- an error in the structure of the tree due to an incorrect program. Or it
3814 -- may be a bug in the optimization circuit. In either case the safest
3815 -- thing is simply to set the check flag unconditionally.
3819 Activate_Overflow_Check (N);
3821 if Debug_Flag_CC then
3822 w (" exception occurred, overflow flag set");
3826 end Enable_Overflow_Check;
3828 ------------------------
3829 -- Enable_Range_Check --
3830 ------------------------
3832 procedure Enable_Range_Check (N : Node_Id) is
3841 -- Return if unchecked type conversion with range check killed. In this
3842 -- case we never set the flag (that's what Kill_Range_Check is about!)
3844 if Nkind (N) = N_Unchecked_Type_Conversion
3845 and then Kill_Range_Check (N)
3850 -- Do not set range check flag if parent is assignment statement or
3851 -- object declaration with Suppress_Assignment_Checks flag set
3853 if Nkind_In (Parent (N), N_Assignment_Statement, N_Object_Declaration)
3854 and then Suppress_Assignment_Checks (Parent (N))
3859 -- Check for various cases where we should suppress the range check
3861 -- No check if range checks suppressed for type of node
3863 if Present (Etype (N))
3864 and then Range_Checks_Suppressed (Etype (N))
3868 -- No check if node is an entity name, and range checks are suppressed
3869 -- for this entity, or for the type of this entity.
3871 elsif Is_Entity_Name (N)
3872 and then (Range_Checks_Suppressed (Entity (N))
3873 or else Range_Checks_Suppressed (Etype (Entity (N))))
3877 -- No checks if index of array, and index checks are suppressed for
3878 -- the array object or the type of the array.
3880 elsif Nkind (Parent (N)) = N_Indexed_Component then
3882 Pref : constant Node_Id := Prefix (Parent (N));
3884 if Is_Entity_Name (Pref)
3885 and then Index_Checks_Suppressed (Entity (Pref))
3888 elsif Index_Checks_Suppressed (Etype (Pref)) then
3894 -- Debug trace output
3896 if Debug_Flag_CC then
3897 w ("Enable_Range_Check for node ", Int (N));
3898 Write_Str (" Source location = ");
3903 -- If not in optimizing mode, set flag and we are done. We are also done
3904 -- (and just set the flag) if the type is not a discrete type, since it
3905 -- is not worth the effort to eliminate checks for other than discrete
3906 -- types. In addition, we take this same path if we have stored the
3907 -- maximum number of checks possible already (a very unlikely situation,
3908 -- but we do not want to blow up!)
3910 if Optimization_Level = 0
3911 or else No (Etype (N))
3912 or else not Is_Discrete_Type (Etype (N))
3913 or else Num_Saved_Checks = Saved_Checks'Last
3915 Activate_Range_Check (N);
3917 if Debug_Flag_CC then
3918 w ("Optimization off");
3924 -- Otherwise find out the target type
3928 -- For assignment, use left side subtype
3930 if Nkind (P) = N_Assignment_Statement
3931 and then Expression (P) = N
3933 Ttyp := Etype (Name (P));
3935 -- For indexed component, use subscript subtype
3937 elsif Nkind (P) = N_Indexed_Component then
3944 Atyp := Etype (Prefix (P));
3946 if Is_Access_Type (Atyp) then
3947 Atyp := Designated_Type (Atyp);
3949 -- If the prefix is an access to an unconstrained array,
3950 -- perform check unconditionally: it depends on the bounds of
3951 -- an object and we cannot currently recognize whether the test
3952 -- may be redundant.
3954 if not Is_Constrained (Atyp) then
3955 Activate_Range_Check (N);
3959 -- Ditto if the prefix is an explicit dereference whose designated
3960 -- type is unconstrained.
3962 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
3963 and then not Is_Constrained (Atyp)
3965 Activate_Range_Check (N);
3969 Indx := First_Index (Atyp);
3970 Subs := First (Expressions (P));
3973 Ttyp := Etype (Indx);
3982 -- For now, ignore all other cases, they are not so interesting
3985 if Debug_Flag_CC then
3986 w (" target type not found, flag set");
3989 Activate_Range_Check (N);
3993 -- Evaluate and check the expression
3998 Target_Type => Ttyp,
4004 if Debug_Flag_CC then
4005 w ("Called Find_Check");
4006 w ("Target_Typ = ", Int (Ttyp));
4010 w (" Check_Num = ", Chk);
4011 w (" Ent = ", Int (Ent));
4012 Write_Str (" Ofs = ");
4017 -- If check is not of form to optimize, then set flag and we are done
4020 if Debug_Flag_CC then
4021 w (" expression not of optimizable type, flag set");
4024 Activate_Range_Check (N);
4028 -- If check is already performed, then return without setting flag
4031 if Debug_Flag_CC then
4032 w ("Check suppressed!");
4038 -- Here we will make a new entry for the new check
4040 Activate_Range_Check (N);
4041 Num_Saved_Checks := Num_Saved_Checks + 1;
4042 Saved_Checks (Num_Saved_Checks) :=
4047 Target_Type => Ttyp);
4049 if Debug_Flag_CC then
4050 w ("Make new entry, check number = ", Num_Saved_Checks);
4051 w (" Entity = ", Int (Ent));
4052 Write_Str (" Offset = ");
4054 w (" Check_Type = R");
4055 w (" Target_Type = ", Int (Ttyp));
4056 pg (Union_Id (Ttyp));
4059 -- If we get an exception, then something went wrong, probably because of
4060 -- an error in the structure of the tree due to an incorrect program. Or
4061 -- it may be a bug in the optimization circuit. In either case the safest
4062 -- thing is simply to set the check flag unconditionally.
4066 Activate_Range_Check (N);
4068 if Debug_Flag_CC then
4069 w (" exception occurred, range flag set");
4073 end Enable_Range_Check;
4079 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
4080 Typ : constant Entity_Id := Etype (Expr);
4083 -- Ignore call if we are not doing any validity checking
4085 if not Validity_Checks_On then
4088 -- Ignore call if range or validity checks suppressed on entity or type
4090 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
4093 -- No check required if expression is from the expander, we assume the
4094 -- expander will generate whatever checks are needed. Note that this is
4095 -- not just an optimization, it avoids infinite recursions!
4097 -- Unchecked conversions must be checked, unless they are initialized
4098 -- scalar values, as in a component assignment in an init proc.
4100 -- In addition, we force a check if Force_Validity_Checks is set
4102 elsif not Comes_From_Source (Expr)
4103 and then not Force_Validity_Checks
4104 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
4105 or else Kill_Range_Check (Expr))
4109 -- No check required if expression is known to have valid value
4111 elsif Expr_Known_Valid (Expr) then
4114 -- Ignore case of enumeration with holes where the flag is set not to
4115 -- worry about holes, since no special validity check is needed
4117 elsif Is_Enumeration_Type (Typ)
4118 and then Has_Non_Standard_Rep (Typ)
4123 -- No check required on the left-hand side of an assignment
4125 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
4126 and then Expr = Name (Parent (Expr))
4130 -- No check on a universal real constant. The context will eventually
4131 -- convert it to a machine number for some target type, or report an
4134 elsif Nkind (Expr) = N_Real_Literal
4135 and then Etype (Expr) = Universal_Real
4139 -- If the expression denotes a component of a packed boolean array,
4140 -- no possible check applies. We ignore the old ACATS chestnuts that
4141 -- involve Boolean range True..True.
4143 -- Note: validity checks are generated for expressions that yield a
4144 -- scalar type, when it is possible to create a value that is outside of
4145 -- the type. If this is a one-bit boolean no such value exists. This is
4146 -- an optimization, and it also prevents compiler blowing up during the
4147 -- elaboration of improperly expanded packed array references.
4149 elsif Nkind (Expr) = N_Indexed_Component
4150 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
4151 and then Root_Type (Etype (Expr)) = Standard_Boolean
4155 -- An annoying special case. If this is an out parameter of a scalar
4156 -- type, then the value is not going to be accessed, therefore it is
4157 -- inappropriate to do any validity check at the call site.
4160 -- Only need to worry about scalar types
4162 if Is_Scalar_Type (Typ) then
4172 -- Find actual argument (which may be a parameter association)
4173 -- and the parent of the actual argument (the call statement)
4178 if Nkind (P) = N_Parameter_Association then
4183 -- Only need to worry if we are argument of a procedure call
4184 -- since functions don't have out parameters. If this is an
4185 -- indirect or dispatching call, get signature from the
4188 if Nkind (P) = N_Procedure_Call_Statement then
4189 L := Parameter_Associations (P);
4191 if Is_Entity_Name (Name (P)) then
4192 E := Entity (Name (P));
4194 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
4195 E := Etype (Name (P));
4198 -- Only need to worry if there are indeed actuals, and if
4199 -- this could be a procedure call, otherwise we cannot get a
4200 -- match (either we are not an argument, or the mode of the
4201 -- formal is not OUT). This test also filters out the
4204 if Is_Non_Empty_List (L)
4205 and then Is_Subprogram (E)
4207 -- This is the loop through parameters, looking for an
4208 -- OUT parameter for which we are the argument.
4210 F := First_Formal (E);
4212 while Present (F) loop
4213 if Ekind (F) = E_Out_Parameter and then A = N then
4226 -- If this is a boolean expression, only its elementary operands need
4227 -- checking: if they are valid, a boolean or short-circuit operation
4228 -- with them will be valid as well.
4230 if Base_Type (Typ) = Standard_Boolean
4232 (Nkind (Expr) in N_Op or else Nkind (Expr) in N_Short_Circuit)
4237 -- If we fall through, a validity check is required
4239 Insert_Valid_Check (Expr);
4241 if Is_Entity_Name (Expr)
4242 and then Safe_To_Capture_Value (Expr, Entity (Expr))
4244 Set_Is_Known_Valid (Entity (Expr));
4248 ----------------------
4249 -- Expr_Known_Valid --
4250 ----------------------
4252 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
4253 Typ : constant Entity_Id := Etype (Expr);
4256 -- Non-scalar types are always considered valid, since they never give
4257 -- rise to the issues of erroneous or bounded error behavior that are
4258 -- the concern. In formal reference manual terms the notion of validity
4259 -- only applies to scalar types. Note that even when packed arrays are
4260 -- represented using modular types, they are still arrays semantically,
4261 -- so they are also always valid (in particular, the unused bits can be
4262 -- random rubbish without affecting the validity of the array value).
4264 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
4267 -- If no validity checking, then everything is considered valid
4269 elsif not Validity_Checks_On then
4272 -- Floating-point types are considered valid unless floating-point
4273 -- validity checks have been specifically turned on.
4275 elsif Is_Floating_Point_Type (Typ)
4276 and then not Validity_Check_Floating_Point
4280 -- If the expression is the value of an object that is known to be
4281 -- valid, then clearly the expression value itself is valid.
4283 elsif Is_Entity_Name (Expr)
4284 and then Is_Known_Valid (Entity (Expr))
4288 -- References to discriminants are always considered valid. The value
4289 -- of a discriminant gets checked when the object is built. Within the
4290 -- record, we consider it valid, and it is important to do so, since
4291 -- otherwise we can try to generate bogus validity checks which
4292 -- reference discriminants out of scope. Discriminants of concurrent
4293 -- types are excluded for the same reason.
4295 elsif Is_Entity_Name (Expr)
4296 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
4300 -- If the type is one for which all values are known valid, then we are
4301 -- sure that the value is valid except in the slightly odd case where
4302 -- the expression is a reference to a variable whose size has been
4303 -- explicitly set to a value greater than the object size.
4305 elsif Is_Known_Valid (Typ) then
4306 if Is_Entity_Name (Expr)
4307 and then Ekind (Entity (Expr)) = E_Variable
4308 and then Esize (Entity (Expr)) > Esize (Typ)
4315 -- Integer and character literals always have valid values, where
4316 -- appropriate these will be range checked in any case.
4318 elsif Nkind (Expr) = N_Integer_Literal
4320 Nkind (Expr) = N_Character_Literal
4324 -- If we have a type conversion or a qualification of a known valid
4325 -- value, then the result will always be valid.
4327 elsif Nkind (Expr) = N_Type_Conversion
4329 Nkind (Expr) = N_Qualified_Expression
4331 return Expr_Known_Valid (Expression (Expr));
4333 -- The result of any operator is always considered valid, since we
4334 -- assume the necessary checks are done by the operator. For operators
4335 -- on floating-point operations, we must also check when the operation
4336 -- is the right-hand side of an assignment, or is an actual in a call.
4338 elsif Nkind (Expr) in N_Op then
4339 if Is_Floating_Point_Type (Typ)
4340 and then Validity_Check_Floating_Point
4342 (Nkind (Parent (Expr)) = N_Assignment_Statement
4343 or else Nkind (Parent (Expr)) = N_Function_Call
4344 or else Nkind (Parent (Expr)) = N_Parameter_Association)
4351 -- The result of a membership test is always valid, since it is true or
4352 -- false, there are no other possibilities.
4354 elsif Nkind (Expr) in N_Membership_Test then
4357 -- For all other cases, we do not know the expression is valid
4362 end Expr_Known_Valid;
4368 procedure Find_Check
4370 Check_Type : Character;
4371 Target_Type : Entity_Id;
4372 Entry_OK : out Boolean;
4373 Check_Num : out Nat;
4374 Ent : out Entity_Id;
4377 function Within_Range_Of
4378 (Target_Type : Entity_Id;
4379 Check_Type : Entity_Id) return Boolean;
4380 -- Given a requirement for checking a range against Target_Type, and
4381 -- and a range Check_Type against which a check has already been made,
4382 -- determines if the check against check type is sufficient to ensure
4383 -- that no check against Target_Type is required.
4385 ---------------------
4386 -- Within_Range_Of --
4387 ---------------------
4389 function Within_Range_Of
4390 (Target_Type : Entity_Id;
4391 Check_Type : Entity_Id) return Boolean
4394 if Target_Type = Check_Type then
4399 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
4400 Thi : constant Node_Id := Type_High_Bound (Target_Type);
4401 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
4402 Chi : constant Node_Id := Type_High_Bound (Check_Type);
4406 or else (Compile_Time_Known_Value (Tlo)
4408 Compile_Time_Known_Value (Clo)
4410 Expr_Value (Clo) >= Expr_Value (Tlo)))
4413 or else (Compile_Time_Known_Value (Thi)
4415 Compile_Time_Known_Value (Chi)
4417 Expr_Value (Chi) <= Expr_Value (Clo)))
4425 end Within_Range_Of;
4427 -- Start of processing for Find_Check
4430 -- Establish default, in case no entry is found
4434 -- Case of expression is simple entity reference
4436 if Is_Entity_Name (Expr) then
4437 Ent := Entity (Expr);
4440 -- Case of expression is entity + known constant
4442 elsif Nkind (Expr) = N_Op_Add
4443 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4444 and then Is_Entity_Name (Left_Opnd (Expr))
4446 Ent := Entity (Left_Opnd (Expr));
4447 Ofs := Expr_Value (Right_Opnd (Expr));
4449 -- Case of expression is entity - known constant
4451 elsif Nkind (Expr) = N_Op_Subtract
4452 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4453 and then Is_Entity_Name (Left_Opnd (Expr))
4455 Ent := Entity (Left_Opnd (Expr));
4456 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
4458 -- Any other expression is not of the right form
4467 -- Come here with expression of appropriate form, check if entity is an
4468 -- appropriate one for our purposes.
4470 if (Ekind (Ent) = E_Variable
4471 or else Is_Constant_Object (Ent))
4472 and then not Is_Library_Level_Entity (Ent)
4480 -- See if there is matching check already
4482 for J in reverse 1 .. Num_Saved_Checks loop
4484 SC : Saved_Check renames Saved_Checks (J);
4487 if SC.Killed = False
4488 and then SC.Entity = Ent
4489 and then SC.Offset = Ofs
4490 and then SC.Check_Type = Check_Type
4491 and then Within_Range_Of (Target_Type, SC.Target_Type)
4499 -- If we fall through entry was not found
4504 ---------------------------------
4505 -- Generate_Discriminant_Check --
4506 ---------------------------------
4508 -- Note: the code for this procedure is derived from the
4509 -- Emit_Discriminant_Check Routine in trans.c.
4511 procedure Generate_Discriminant_Check (N : Node_Id) is
4512 Loc : constant Source_Ptr := Sloc (N);
4513 Pref : constant Node_Id := Prefix (N);
4514 Sel : constant Node_Id := Selector_Name (N);
4516 Orig_Comp : constant Entity_Id :=
4517 Original_Record_Component (Entity (Sel));
4518 -- The original component to be checked
4520 Discr_Fct : constant Entity_Id :=
4521 Discriminant_Checking_Func (Orig_Comp);
4522 -- The discriminant checking function
4525 -- One discriminant to be checked in the type
4527 Real_Discr : Entity_Id;
4528 -- Actual discriminant in the call
4530 Pref_Type : Entity_Id;
4531 -- Type of relevant prefix (ignoring private/access stuff)
4534 -- List of arguments for function call
4537 -- Keep track of the formal corresponding to the actual we build for
4538 -- each discriminant, in order to be able to perform the necessary type
4542 -- Selected component reference for checking function argument
4545 Pref_Type := Etype (Pref);
4547 -- Force evaluation of the prefix, so that it does not get evaluated
4548 -- twice (once for the check, once for the actual reference). Such a
4549 -- double evaluation is always a potential source of inefficiency,
4550 -- and is functionally incorrect in the volatile case, or when the
4551 -- prefix may have side-effects. An entity or a component of an
4552 -- entity requires no evaluation.
4554 if Is_Entity_Name (Pref) then
4555 if Treat_As_Volatile (Entity (Pref)) then
4556 Force_Evaluation (Pref, Name_Req => True);
4559 elsif Treat_As_Volatile (Etype (Pref)) then
4560 Force_Evaluation (Pref, Name_Req => True);
4562 elsif Nkind (Pref) = N_Selected_Component
4563 and then Is_Entity_Name (Prefix (Pref))
4568 Force_Evaluation (Pref, Name_Req => True);
4571 -- For a tagged type, use the scope of the original component to
4572 -- obtain the type, because ???
4574 if Is_Tagged_Type (Scope (Orig_Comp)) then
4575 Pref_Type := Scope (Orig_Comp);
4577 -- For an untagged derived type, use the discriminants of the parent
4578 -- which have been renamed in the derivation, possibly by a one-to-many
4579 -- discriminant constraint. For non-tagged type, initially get the Etype
4583 if Is_Derived_Type (Pref_Type)
4584 and then Number_Discriminants (Pref_Type) /=
4585 Number_Discriminants (Etype (Base_Type (Pref_Type)))
4587 Pref_Type := Etype (Base_Type (Pref_Type));
4591 -- We definitely should have a checking function, This routine should
4592 -- not be called if no discriminant checking function is present.
4594 pragma Assert (Present (Discr_Fct));
4596 -- Create the list of the actual parameters for the call. This list
4597 -- is the list of the discriminant fields of the record expression to
4598 -- be discriminant checked.
4601 Formal := First_Formal (Discr_Fct);
4602 Discr := First_Discriminant (Pref_Type);
4603 while Present (Discr) loop
4605 -- If we have a corresponding discriminant field, and a parent
4606 -- subtype is present, then we want to use the corresponding
4607 -- discriminant since this is the one with the useful value.
4609 if Present (Corresponding_Discriminant (Discr))
4610 and then Ekind (Pref_Type) = E_Record_Type
4611 and then Present (Parent_Subtype (Pref_Type))
4613 Real_Discr := Corresponding_Discriminant (Discr);
4615 Real_Discr := Discr;
4618 -- Construct the reference to the discriminant
4621 Make_Selected_Component (Loc,
4623 Unchecked_Convert_To (Pref_Type,
4624 Duplicate_Subexpr (Pref)),
4625 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
4627 -- Manually analyze and resolve this selected component. We really
4628 -- want it just as it appears above, and do not want the expander
4629 -- playing discriminal games etc with this reference. Then we append
4630 -- the argument to the list we are gathering.
4632 Set_Etype (Scomp, Etype (Real_Discr));
4633 Set_Analyzed (Scomp, True);
4634 Append_To (Args, Convert_To (Etype (Formal), Scomp));
4636 Next_Formal_With_Extras (Formal);
4637 Next_Discriminant (Discr);
4640 -- Now build and insert the call
4643 Make_Raise_Constraint_Error (Loc,
4645 Make_Function_Call (Loc,
4646 Name => New_Occurrence_Of (Discr_Fct, Loc),
4647 Parameter_Associations => Args),
4648 Reason => CE_Discriminant_Check_Failed));
4649 end Generate_Discriminant_Check;
4651 ---------------------------
4652 -- Generate_Index_Checks --
4653 ---------------------------
4655 procedure Generate_Index_Checks (N : Node_Id) is
4657 function Entity_Of_Prefix return Entity_Id;
4658 -- Returns the entity of the prefix of N (or Empty if not found)
4660 ----------------------
4661 -- Entity_Of_Prefix --
4662 ----------------------
4664 function Entity_Of_Prefix return Entity_Id is
4669 while not Is_Entity_Name (P) loop
4670 if not Nkind_In (P, N_Selected_Component,
4671 N_Indexed_Component)
4680 end Entity_Of_Prefix;
4684 Loc : constant Source_Ptr := Sloc (N);
4685 A : constant Node_Id := Prefix (N);
4686 A_Ent : constant Entity_Id := Entity_Of_Prefix;
4689 -- Start of processing for Generate_Index_Checks
4692 -- Ignore call if the prefix is not an array since we have a serious
4693 -- error in the sources. Ignore it also if index checks are suppressed
4694 -- for array object or type.
4696 if not Is_Array_Type (Etype (A))
4697 or else (Present (A_Ent)
4698 and then Index_Checks_Suppressed (A_Ent))
4699 or else Index_Checks_Suppressed (Etype (A))
4704 -- Generate a raise of constraint error with the appropriate reason and
4705 -- a condition of the form:
4707 -- Base_Type (Sub) not in Array'Range (Subscript)
4709 -- Note that the reason we generate the conversion to the base type here
4710 -- is that we definitely want the range check to take place, even if it
4711 -- looks like the subtype is OK. Optimization considerations that allow
4712 -- us to omit the check have already been taken into account in the
4713 -- setting of the Do_Range_Check flag earlier on.
4715 Sub := First (Expressions (N));
4717 -- Handle string literals
4719 if Ekind (Etype (A)) = E_String_Literal_Subtype then
4720 if Do_Range_Check (Sub) then
4721 Set_Do_Range_Check (Sub, False);
4723 -- For string literals we obtain the bounds of the string from the
4724 -- associated subtype.
4727 Make_Raise_Constraint_Error (Loc,
4731 Convert_To (Base_Type (Etype (Sub)),
4732 Duplicate_Subexpr_Move_Checks (Sub)),
4734 Make_Attribute_Reference (Loc,
4735 Prefix => New_Reference_To (Etype (A), Loc),
4736 Attribute_Name => Name_Range)),
4737 Reason => CE_Index_Check_Failed));
4744 A_Idx : Node_Id := Empty;
4751 A_Idx := First_Index (Etype (A));
4753 while Present (Sub) loop
4754 if Do_Range_Check (Sub) then
4755 Set_Do_Range_Check (Sub, False);
4757 -- Force evaluation except for the case of a simple name of
4758 -- a non-volatile entity.
4760 if not Is_Entity_Name (Sub)
4761 or else Treat_As_Volatile (Entity (Sub))
4763 Force_Evaluation (Sub);
4766 if Nkind (A_Idx) = N_Range then
4769 elsif Nkind (A_Idx) = N_Identifier
4770 or else Nkind (A_Idx) = N_Expanded_Name
4772 A_Range := Scalar_Range (Entity (A_Idx));
4774 else pragma Assert (Nkind (A_Idx) = N_Subtype_Indication);
4775 A_Range := Range_Expression (Constraint (A_Idx));
4778 -- For array objects with constant bounds we can generate
4779 -- the index check using the bounds of the type of the index
4782 and then Ekind (A_Ent) = E_Variable
4783 and then Is_Constant_Bound (Low_Bound (A_Range))
4784 and then Is_Constant_Bound (High_Bound (A_Range))
4787 Make_Attribute_Reference (Loc,
4789 New_Reference_To (Etype (A_Idx), Loc),
4790 Attribute_Name => Name_Range);
4792 -- For arrays with non-constant bounds we cannot generate
4793 -- the index check using the bounds of the type of the index
4794 -- since it may reference discriminants of some enclosing
4795 -- type. We obtain the bounds directly from the prefix
4802 Num := New_List (Make_Integer_Literal (Loc, Ind));
4806 Make_Attribute_Reference (Loc,
4808 Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
4809 Attribute_Name => Name_Range,
4810 Expressions => Num);
4814 Make_Raise_Constraint_Error (Loc,
4818 Convert_To (Base_Type (Etype (Sub)),
4819 Duplicate_Subexpr_Move_Checks (Sub)),
4820 Right_Opnd => Range_N),
4821 Reason => CE_Index_Check_Failed));
4824 A_Idx := Next_Index (A_Idx);
4830 end Generate_Index_Checks;
4832 --------------------------
4833 -- Generate_Range_Check --
4834 --------------------------
4836 procedure Generate_Range_Check
4838 Target_Type : Entity_Id;
4839 Reason : RT_Exception_Code)
4841 Loc : constant Source_Ptr := Sloc (N);
4842 Source_Type : constant Entity_Id := Etype (N);
4843 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
4844 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
4847 -- First special case, if the source type is already within the range
4848 -- of the target type, then no check is needed (probably we should have
4849 -- stopped Do_Range_Check from being set in the first place, but better
4850 -- late than later in preventing junk code!
4852 -- We do NOT apply this if the source node is a literal, since in this
4853 -- case the literal has already been labeled as having the subtype of
4856 if In_Subrange_Of (Source_Type, Target_Type)
4858 (Nkind (N) = N_Integer_Literal
4860 Nkind (N) = N_Real_Literal
4862 Nkind (N) = N_Character_Literal
4865 and then Ekind (Entity (N)) = E_Enumeration_Literal))
4870 -- We need a check, so force evaluation of the node, so that it does
4871 -- not get evaluated twice (once for the check, once for the actual
4872 -- reference). Such a double evaluation is always a potential source
4873 -- of inefficiency, and is functionally incorrect in the volatile case.
4875 if not Is_Entity_Name (N)
4876 or else Treat_As_Volatile (Entity (N))
4878 Force_Evaluation (N);
4881 -- The easiest case is when Source_Base_Type and Target_Base_Type are
4882 -- the same since in this case we can simply do a direct check of the
4883 -- value of N against the bounds of Target_Type.
4885 -- [constraint_error when N not in Target_Type]
4887 -- Note: this is by far the most common case, for example all cases of
4888 -- checks on the RHS of assignments are in this category, but not all
4889 -- cases are like this. Notably conversions can involve two types.
4891 if Source_Base_Type = Target_Base_Type then
4893 Make_Raise_Constraint_Error (Loc,
4896 Left_Opnd => Duplicate_Subexpr (N),
4897 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4900 -- Next test for the case where the target type is within the bounds
4901 -- of the base type of the source type, since in this case we can
4902 -- simply convert these bounds to the base type of T to do the test.
4904 -- [constraint_error when N not in
4905 -- Source_Base_Type (Target_Type'First)
4907 -- Source_Base_Type(Target_Type'Last))]
4909 -- The conversions will always work and need no check
4911 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
4912 -- of converting from an enumeration value to an integer type, such as
4913 -- occurs for the case of generating a range check on Enum'Val(Exp)
4914 -- (which used to be handled by gigi). This is OK, since the conversion
4915 -- itself does not require a check.
4917 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
4919 Make_Raise_Constraint_Error (Loc,
4922 Left_Opnd => Duplicate_Subexpr (N),
4927 Unchecked_Convert_To (Source_Base_Type,
4928 Make_Attribute_Reference (Loc,
4930 New_Occurrence_Of (Target_Type, Loc),
4931 Attribute_Name => Name_First)),
4934 Unchecked_Convert_To (Source_Base_Type,
4935 Make_Attribute_Reference (Loc,
4937 New_Occurrence_Of (Target_Type, Loc),
4938 Attribute_Name => Name_Last)))),
4941 -- Note that at this stage we now that the Target_Base_Type is not in
4942 -- the range of the Source_Base_Type (since even the Target_Type itself
4943 -- is not in this range). It could still be the case that Source_Type is
4944 -- in range of the target base type since we have not checked that case.
4946 -- If that is the case, we can freely convert the source to the target,
4947 -- and then test the target result against the bounds.
4949 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
4951 -- We make a temporary to hold the value of the converted value
4952 -- (converted to the base type), and then we will do the test against
4955 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
4956 -- [constraint_error when Tnn not in Target_Type]
4958 -- Then the conversion itself is replaced by an occurrence of Tnn
4961 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
4964 Insert_Actions (N, New_List (
4965 Make_Object_Declaration (Loc,
4966 Defining_Identifier => Tnn,
4967 Object_Definition =>
4968 New_Occurrence_Of (Target_Base_Type, Loc),
4969 Constant_Present => True,
4971 Make_Type_Conversion (Loc,
4972 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
4973 Expression => Duplicate_Subexpr (N))),
4975 Make_Raise_Constraint_Error (Loc,
4978 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4979 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4981 Reason => Reason)));
4983 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4985 -- Set the type of N, because the declaration for Tnn might not
4986 -- be analyzed yet, as is the case if N appears within a record
4987 -- declaration, as a discriminant constraint or expression.
4989 Set_Etype (N, Target_Base_Type);
4992 -- At this stage, we know that we have two scalar types, which are
4993 -- directly convertible, and where neither scalar type has a base
4994 -- range that is in the range of the other scalar type.
4996 -- The only way this can happen is with a signed and unsigned type.
4997 -- So test for these two cases:
5000 -- Case of the source is unsigned and the target is signed
5002 if Is_Unsigned_Type (Source_Base_Type)
5003 and then not Is_Unsigned_Type (Target_Base_Type)
5005 -- If the source is unsigned and the target is signed, then we
5006 -- know that the source is not shorter than the target (otherwise
5007 -- the source base type would be in the target base type range).
5009 -- In other words, the unsigned type is either the same size as
5010 -- the target, or it is larger. It cannot be smaller.
5013 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
5015 -- We only need to check the low bound if the low bound of the
5016 -- target type is non-negative. If the low bound of the target
5017 -- type is negative, then we know that we will fit fine.
5019 -- If the high bound of the target type is negative, then we
5020 -- know we have a constraint error, since we can't possibly
5021 -- have a negative source.
5023 -- With these two checks out of the way, we can do the check
5024 -- using the source type safely
5026 -- This is definitely the most annoying case!
5028 -- [constraint_error
5029 -- when (Target_Type'First >= 0
5031 -- N < Source_Base_Type (Target_Type'First))
5032 -- or else Target_Type'Last < 0
5033 -- or else N > Source_Base_Type (Target_Type'Last)];
5035 -- We turn off all checks since we know that the conversions
5036 -- will work fine, given the guards for negative values.
5039 Make_Raise_Constraint_Error (Loc,
5045 Left_Opnd => Make_Op_Ge (Loc,
5047 Make_Attribute_Reference (Loc,
5049 New_Occurrence_Of (Target_Type, Loc),
5050 Attribute_Name => Name_First),
5051 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
5055 Left_Opnd => Duplicate_Subexpr (N),
5057 Convert_To (Source_Base_Type,
5058 Make_Attribute_Reference (Loc,
5060 New_Occurrence_Of (Target_Type, Loc),
5061 Attribute_Name => Name_First)))),
5066 Make_Attribute_Reference (Loc,
5067 Prefix => New_Occurrence_Of (Target_Type, Loc),
5068 Attribute_Name => Name_Last),
5069 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
5073 Left_Opnd => Duplicate_Subexpr (N),
5075 Convert_To (Source_Base_Type,
5076 Make_Attribute_Reference (Loc,
5077 Prefix => New_Occurrence_Of (Target_Type, Loc),
5078 Attribute_Name => Name_Last)))),
5081 Suppress => All_Checks);
5083 -- Only remaining possibility is that the source is signed and
5084 -- the target is unsigned.
5087 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
5088 and then Is_Unsigned_Type (Target_Base_Type));
5090 -- If the source is signed and the target is unsigned, then we
5091 -- know that the target is not shorter than the source (otherwise
5092 -- the target base type would be in the source base type range).
5094 -- In other words, the unsigned type is either the same size as
5095 -- the target, or it is larger. It cannot be smaller.
5097 -- Clearly we have an error if the source value is negative since
5098 -- no unsigned type can have negative values. If the source type
5099 -- is non-negative, then the check can be done using the target
5102 -- Tnn : constant Target_Base_Type (N) := Target_Type;
5104 -- [constraint_error
5105 -- when N < 0 or else Tnn not in Target_Type];
5107 -- We turn off all checks for the conversion of N to the target
5108 -- base type, since we generate the explicit check to ensure that
5109 -- the value is non-negative
5112 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
5115 Insert_Actions (N, New_List (
5116 Make_Object_Declaration (Loc,
5117 Defining_Identifier => Tnn,
5118 Object_Definition =>
5119 New_Occurrence_Of (Target_Base_Type, Loc),
5120 Constant_Present => True,
5122 Make_Unchecked_Type_Conversion (Loc,
5124 New_Occurrence_Of (Target_Base_Type, Loc),
5125 Expression => Duplicate_Subexpr (N))),
5127 Make_Raise_Constraint_Error (Loc,
5132 Left_Opnd => Duplicate_Subexpr (N),
5133 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
5137 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
5139 New_Occurrence_Of (Target_Type, Loc))),
5142 Suppress => All_Checks);
5144 -- Set the Etype explicitly, because Insert_Actions may have
5145 -- placed the declaration in the freeze list for an enclosing
5146 -- construct, and thus it is not analyzed yet.
5148 Set_Etype (Tnn, Target_Base_Type);
5149 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
5153 end Generate_Range_Check;
5159 function Get_Check_Id (N : Name_Id) return Check_Id is
5161 -- For standard check name, we can do a direct computation
5163 if N in First_Check_Name .. Last_Check_Name then
5164 return Check_Id (N - (First_Check_Name - 1));
5166 -- For non-standard names added by pragma Check_Name, search table
5169 for J in All_Checks + 1 .. Check_Names.Last loop
5170 if Check_Names.Table (J) = N then
5176 -- No matching name found
5181 ---------------------
5182 -- Get_Discriminal --
5183 ---------------------
5185 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
5186 Loc : constant Source_Ptr := Sloc (E);
5191 -- The bound can be a bona fide parameter of a protected operation,
5192 -- rather than a prival encoded as an in-parameter.
5194 if No (Discriminal_Link (Entity (Bound))) then
5198 -- Climb the scope stack looking for an enclosing protected type. If
5199 -- we run out of scopes, return the bound itself.
5202 while Present (Sc) loop
5203 if Sc = Standard_Standard then
5206 elsif Ekind (Sc) = E_Protected_Type then
5213 D := First_Discriminant (Sc);
5214 while Present (D) loop
5215 if Chars (D) = Chars (Bound) then
5216 return New_Occurrence_Of (Discriminal (D), Loc);
5219 Next_Discriminant (D);
5223 end Get_Discriminal;
5225 ----------------------
5226 -- Get_Range_Checks --
5227 ----------------------
5229 function Get_Range_Checks
5231 Target_Typ : Entity_Id;
5232 Source_Typ : Entity_Id := Empty;
5233 Warn_Node : Node_Id := Empty) return Check_Result
5236 return Selected_Range_Checks
5237 (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
5238 end Get_Range_Checks;
5244 function Guard_Access
5247 Ck_Node : Node_Id) return Node_Id
5250 if Nkind (Cond) = N_Or_Else then
5251 Set_Paren_Count (Cond, 1);
5254 if Nkind (Ck_Node) = N_Allocator then
5261 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
5262 Right_Opnd => Make_Null (Loc)),
5263 Right_Opnd => Cond);
5267 -----------------------------
5268 -- Index_Checks_Suppressed --
5269 -----------------------------
5271 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
5273 if Present (E) and then Checks_May_Be_Suppressed (E) then
5274 return Is_Check_Suppressed (E, Index_Check);
5276 return Scope_Suppress (Index_Check);
5278 end Index_Checks_Suppressed;
5284 procedure Initialize is
5286 for J in Determine_Range_Cache_N'Range loop
5287 Determine_Range_Cache_N (J) := Empty;
5292 for J in Int range 1 .. All_Checks loop
5293 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
5297 -------------------------
5298 -- Insert_Range_Checks --
5299 -------------------------
5301 procedure Insert_Range_Checks
5302 (Checks : Check_Result;
5304 Suppress_Typ : Entity_Id;
5305 Static_Sloc : Source_Ptr := No_Location;
5306 Flag_Node : Node_Id := Empty;
5307 Do_Before : Boolean := False)
5309 Internal_Flag_Node : Node_Id := Flag_Node;
5310 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
5312 Check_Node : Node_Id;
5313 Checks_On : constant Boolean :=
5314 (not Index_Checks_Suppressed (Suppress_Typ))
5316 (not Range_Checks_Suppressed (Suppress_Typ));
5319 -- For now we just return if Checks_On is false, however this should be
5320 -- enhanced to check for an always True value in the condition and to
5321 -- generate a compilation warning???
5323 if not Full_Expander_Active or else not Checks_On then
5327 if Static_Sloc = No_Location then
5328 Internal_Static_Sloc := Sloc (Node);
5331 if No (Flag_Node) then
5332 Internal_Flag_Node := Node;
5335 for J in 1 .. 2 loop
5336 exit when No (Checks (J));
5338 if Nkind (Checks (J)) = N_Raise_Constraint_Error
5339 and then Present (Condition (Checks (J)))
5341 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
5342 Check_Node := Checks (J);
5343 Mark_Rewrite_Insertion (Check_Node);
5346 Insert_Before_And_Analyze (Node, Check_Node);
5348 Insert_After_And_Analyze (Node, Check_Node);
5351 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
5356 Make_Raise_Constraint_Error (Internal_Static_Sloc,
5357 Reason => CE_Range_Check_Failed);
5358 Mark_Rewrite_Insertion (Check_Node);
5361 Insert_Before_And_Analyze (Node, Check_Node);
5363 Insert_After_And_Analyze (Node, Check_Node);
5367 end Insert_Range_Checks;
5369 ------------------------
5370 -- Insert_Valid_Check --
5371 ------------------------
5373 procedure Insert_Valid_Check (Expr : Node_Id) is
5374 Loc : constant Source_Ptr := Sloc (Expr);
5378 -- Do not insert if checks off, or if not checking validity or
5379 -- if expression is known to be valid
5381 if not Validity_Checks_On
5382 or else Range_Or_Validity_Checks_Suppressed (Expr)
5383 or else Expr_Known_Valid (Expr)
5388 -- If we have a checked conversion, then validity check applies to
5389 -- the expression inside the conversion, not the result, since if
5390 -- the expression inside is valid, then so is the conversion result.
5393 while Nkind (Exp) = N_Type_Conversion loop
5394 Exp := Expression (Exp);
5397 -- We are about to insert the validity check for Exp. We save and
5398 -- reset the Do_Range_Check flag over this validity check, and then
5399 -- put it back for the final original reference (Exp may be rewritten).
5402 DRC : constant Boolean := Do_Range_Check (Exp);
5405 Set_Do_Range_Check (Exp, False);
5407 -- Force evaluation to avoid multiple reads for atomic/volatile
5409 if Is_Entity_Name (Exp)
5410 and then Is_Volatile (Entity (Exp))
5412 Force_Evaluation (Exp, Name_Req => True);
5415 -- Insert the validity check. Note that we do this with validity
5416 -- checks turned off, to avoid recursion, we do not want validity
5417 -- checks on the validity checking code itself!
5421 Make_Raise_Constraint_Error (Loc,
5425 Make_Attribute_Reference (Loc,
5427 Duplicate_Subexpr_No_Checks (Exp, Name_Req => True),
5428 Attribute_Name => Name_Valid)),
5429 Reason => CE_Invalid_Data),
5430 Suppress => Validity_Check);
5432 -- If the expression is a reference to an element of a bit-packed
5433 -- array, then it is rewritten as a renaming declaration. If the
5434 -- expression is an actual in a call, it has not been expanded,
5435 -- waiting for the proper point at which to do it. The same happens
5436 -- with renamings, so that we have to force the expansion now. This
5437 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
5440 if Is_Entity_Name (Exp)
5441 and then Nkind (Parent (Entity (Exp))) =
5442 N_Object_Renaming_Declaration
5445 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
5447 if Nkind (Old_Exp) = N_Indexed_Component
5448 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
5450 Expand_Packed_Element_Reference (Old_Exp);
5455 -- Put back the Do_Range_Check flag on the resulting (possibly
5456 -- rewritten) expression.
5458 -- Note: it might be thought that a validity check is not required
5459 -- when a range check is present, but that's not the case, because
5460 -- the back end is allowed to assume for the range check that the
5461 -- operand is within its declared range (an assumption that validity
5462 -- checking is all about NOT assuming!)
5464 -- Note: no need to worry about Possible_Local_Raise here, it will
5465 -- already have been called if original node has Do_Range_Check set.
5467 Set_Do_Range_Check (Exp, DRC);
5469 end Insert_Valid_Check;
5471 ----------------------------------
5472 -- Install_Null_Excluding_Check --
5473 ----------------------------------
5475 procedure Install_Null_Excluding_Check (N : Node_Id) is
5476 Loc : constant Source_Ptr := Sloc (Parent (N));
5477 Typ : constant Entity_Id := Etype (N);
5479 function Safe_To_Capture_In_Parameter_Value return Boolean;
5480 -- Determines if it is safe to capture Known_Non_Null status for an
5481 -- the entity referenced by node N. The caller ensures that N is indeed
5482 -- an entity name. It is safe to capture the non-null status for an IN
5483 -- parameter when the reference occurs within a declaration that is sure
5484 -- to be executed as part of the declarative region.
5486 procedure Mark_Non_Null;
5487 -- After installation of check, if the node in question is an entity
5488 -- name, then mark this entity as non-null if possible.
5490 function Safe_To_Capture_In_Parameter_Value return Boolean is
5491 E : constant Entity_Id := Entity (N);
5492 S : constant Entity_Id := Current_Scope;
5496 if Ekind (E) /= E_In_Parameter then
5500 -- Two initial context checks. We must be inside a subprogram body
5501 -- with declarations and reference must not appear in nested scopes.
5503 if (Ekind (S) /= E_Function and then Ekind (S) /= E_Procedure)
5504 or else Scope (E) /= S
5509 S_Par := Parent (Parent (S));
5511 if Nkind (S_Par) /= N_Subprogram_Body
5512 or else No (Declarations (S_Par))
5522 -- Retrieve the declaration node of N (if any). Note that N
5523 -- may be a part of a complex initialization expression.
5527 while Present (P) loop
5529 -- If we have a short circuit form, and we are within the right
5530 -- hand expression, we return false, since the right hand side
5531 -- is not guaranteed to be elaborated.
5533 if Nkind (P) in N_Short_Circuit
5534 and then N = Right_Opnd (P)
5539 -- Similarly, if we are in a conditional expression and not
5540 -- part of the condition, then we return False, since neither
5541 -- the THEN or ELSE expressions will always be elaborated.
5543 if Nkind (P) = N_Conditional_Expression
5544 and then N /= First (Expressions (P))
5549 -- If we are in a case expression, and not part of the
5550 -- expression, then we return False, since a particular
5551 -- branch may not always be elaborated
5553 if Nkind (P) = N_Case_Expression
5554 and then N /= Expression (P)
5559 -- While traversing the parent chain, we find that N
5560 -- belongs to a statement, thus it may never appear in
5561 -- a declarative region.
5563 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
5564 or else Nkind (P) = N_Procedure_Call_Statement
5569 -- If we are at a declaration, record it and exit
5571 if Nkind (P) in N_Declaration
5572 and then Nkind (P) not in N_Subprogram_Specification
5585 return List_Containing (N_Decl) = Declarations (S_Par);
5587 end Safe_To_Capture_In_Parameter_Value;
5593 procedure Mark_Non_Null is
5595 -- Only case of interest is if node N is an entity name
5597 if Is_Entity_Name (N) then
5599 -- For sure, we want to clear an indication that this is known to
5600 -- be null, since if we get past this check, it definitely is not!
5602 Set_Is_Known_Null (Entity (N), False);
5604 -- We can mark the entity as known to be non-null if either it is
5605 -- safe to capture the value, or in the case of an IN parameter,
5606 -- which is a constant, if the check we just installed is in the
5607 -- declarative region of the subprogram body. In this latter case,
5608 -- a check is decisive for the rest of the body if the expression
5609 -- is sure to be elaborated, since we know we have to elaborate
5610 -- all declarations before executing the body.
5612 -- Couldn't this always be part of Safe_To_Capture_Value ???
5614 if Safe_To_Capture_Value (N, Entity (N))
5615 or else Safe_To_Capture_In_Parameter_Value
5617 Set_Is_Known_Non_Null (Entity (N));
5622 -- Start of processing for Install_Null_Excluding_Check
5625 pragma Assert (Is_Access_Type (Typ));
5627 -- No check inside a generic (why not???)
5629 if Inside_A_Generic then
5633 -- No check needed if known to be non-null
5635 if Known_Non_Null (N) then
5639 -- If known to be null, here is where we generate a compile time check
5641 if Known_Null (N) then
5643 -- Avoid generating warning message inside init procs
5645 if not Inside_Init_Proc then
5646 Apply_Compile_Time_Constraint_Error
5648 "null value not allowed here?",
5649 CE_Access_Check_Failed);
5652 Make_Raise_Constraint_Error (Loc,
5653 Reason => CE_Access_Check_Failed));
5660 -- If entity is never assigned, for sure a warning is appropriate
5662 if Is_Entity_Name (N) then
5663 Check_Unset_Reference (N);
5666 -- No check needed if checks are suppressed on the range. Note that we
5667 -- don't set Is_Known_Non_Null in this case (we could legitimately do
5668 -- so, since the program is erroneous, but we don't like to casually
5669 -- propagate such conclusions from erroneosity).
5671 if Access_Checks_Suppressed (Typ) then
5675 -- No check needed for access to concurrent record types generated by
5676 -- the expander. This is not just an optimization (though it does indeed
5677 -- remove junk checks). It also avoids generation of junk warnings.
5679 if Nkind (N) in N_Has_Chars
5680 and then Chars (N) = Name_uObject
5681 and then Is_Concurrent_Record_Type
5682 (Directly_Designated_Type (Etype (N)))
5687 -- No check needed for the Get_Current_Excep.all.all idiom generated by
5688 -- the expander within exception handlers, since we know that the value
5689 -- can never be null.
5691 -- Is this really the right way to do this? Normally we generate such
5692 -- code in the expander with checks off, and that's how we suppress this
5693 -- kind of junk check ???
5695 if Nkind (N) = N_Function_Call
5696 and then Nkind (Name (N)) = N_Explicit_Dereference
5697 and then Nkind (Prefix (Name (N))) = N_Identifier
5698 and then Is_RTE (Entity (Prefix (Name (N))), RE_Get_Current_Excep)
5703 -- Otherwise install access check
5706 Make_Raise_Constraint_Error (Loc,
5709 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
5710 Right_Opnd => Make_Null (Loc)),
5711 Reason => CE_Access_Check_Failed));
5714 end Install_Null_Excluding_Check;
5716 --------------------------
5717 -- Install_Static_Check --
5718 --------------------------
5720 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
5721 Stat : constant Boolean := Is_Static_Expression (R_Cno);
5722 Typ : constant Entity_Id := Etype (R_Cno);
5726 Make_Raise_Constraint_Error (Loc,
5727 Reason => CE_Range_Check_Failed));
5728 Set_Analyzed (R_Cno);
5729 Set_Etype (R_Cno, Typ);
5730 Set_Raises_Constraint_Error (R_Cno);
5731 Set_Is_Static_Expression (R_Cno, Stat);
5733 -- Now deal with possible local raise handling
5735 Possible_Local_Raise (R_Cno, Standard_Constraint_Error);
5736 end Install_Static_Check;
5738 ---------------------
5739 -- Kill_All_Checks --
5740 ---------------------
5742 procedure Kill_All_Checks is
5744 if Debug_Flag_CC then
5745 w ("Kill_All_Checks");
5748 -- We reset the number of saved checks to zero, and also modify all
5749 -- stack entries for statement ranges to indicate that the number of
5750 -- checks at each level is now zero.
5752 Num_Saved_Checks := 0;
5754 -- Note: the Int'Min here avoids any possibility of J being out of
5755 -- range when called from e.g. Conditional_Statements_Begin.
5757 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
5758 Saved_Checks_Stack (J) := 0;
5760 end Kill_All_Checks;
5766 procedure Kill_Checks (V : Entity_Id) is
5768 if Debug_Flag_CC then
5769 w ("Kill_Checks for entity", Int (V));
5772 for J in 1 .. Num_Saved_Checks loop
5773 if Saved_Checks (J).Entity = V then
5774 if Debug_Flag_CC then
5775 w (" Checks killed for saved check ", J);
5778 Saved_Checks (J).Killed := True;
5783 ------------------------------
5784 -- Length_Checks_Suppressed --
5785 ------------------------------
5787 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
5789 if Present (E) and then Checks_May_Be_Suppressed (E) then
5790 return Is_Check_Suppressed (E, Length_Check);
5792 return Scope_Suppress (Length_Check);
5794 end Length_Checks_Suppressed;
5796 --------------------------------
5797 -- Overflow_Checks_Suppressed --
5798 --------------------------------
5800 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
5802 if Present (E) and then Checks_May_Be_Suppressed (E) then
5803 return Is_Check_Suppressed (E, Overflow_Check);
5805 return Scope_Suppress (Overflow_Check);
5807 end Overflow_Checks_Suppressed;
5809 -----------------------------
5810 -- Range_Checks_Suppressed --
5811 -----------------------------
5813 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
5817 -- Note: for now we always suppress range checks on Vax float types,
5818 -- since Gigi does not know how to generate these checks.
5820 if Vax_Float (E) then
5822 elsif Kill_Range_Checks (E) then
5824 elsif Checks_May_Be_Suppressed (E) then
5825 return Is_Check_Suppressed (E, Range_Check);
5829 return Scope_Suppress (Range_Check);
5830 end Range_Checks_Suppressed;
5832 -----------------------------------------
5833 -- Range_Or_Validity_Checks_Suppressed --
5834 -----------------------------------------
5836 -- Note: the coding would be simpler here if we simply made appropriate
5837 -- calls to Range/Validity_Checks_Suppressed, but that would result in
5838 -- duplicated checks which we prefer to avoid.
5840 function Range_Or_Validity_Checks_Suppressed
5841 (Expr : Node_Id) return Boolean
5844 -- Immediate return if scope checks suppressed for either check
5846 if Scope_Suppress (Range_Check) or Scope_Suppress (Validity_Check) then
5850 -- If no expression, that's odd, decide that checks are suppressed,
5851 -- since we don't want anyone trying to do checks in this case, which
5852 -- is most likely the result of some other error.
5858 -- Expression is present, so perform suppress checks on type
5861 Typ : constant Entity_Id := Etype (Expr);
5863 if Vax_Float (Typ) then
5865 elsif Checks_May_Be_Suppressed (Typ)
5866 and then (Is_Check_Suppressed (Typ, Range_Check)
5868 Is_Check_Suppressed (Typ, Validity_Check))
5874 -- If expression is an entity name, perform checks on this entity
5876 if Is_Entity_Name (Expr) then
5878 Ent : constant Entity_Id := Entity (Expr);
5880 if Checks_May_Be_Suppressed (Ent) then
5881 return Is_Check_Suppressed (Ent, Range_Check)
5882 or else Is_Check_Suppressed (Ent, Validity_Check);
5887 -- If we fall through, no checks suppressed
5890 end Range_Or_Validity_Checks_Suppressed;
5896 procedure Remove_Checks (Expr : Node_Id) is
5897 function Process (N : Node_Id) return Traverse_Result;
5898 -- Process a single node during the traversal
5900 procedure Traverse is new Traverse_Proc (Process);
5901 -- The traversal procedure itself
5907 function Process (N : Node_Id) return Traverse_Result is
5909 if Nkind (N) not in N_Subexpr then
5913 Set_Do_Range_Check (N, False);
5917 Traverse (Left_Opnd (N));
5920 when N_Attribute_Reference =>
5921 Set_Do_Overflow_Check (N, False);
5923 when N_Function_Call =>
5924 Set_Do_Tag_Check (N, False);
5927 Set_Do_Overflow_Check (N, False);
5931 Set_Do_Division_Check (N, False);
5934 Set_Do_Length_Check (N, False);
5937 Set_Do_Division_Check (N, False);
5940 Set_Do_Length_Check (N, False);
5943 Set_Do_Division_Check (N, False);
5946 Set_Do_Length_Check (N, False);
5953 Traverse (Left_Opnd (N));
5956 when N_Selected_Component =>
5957 Set_Do_Discriminant_Check (N, False);
5959 when N_Type_Conversion =>
5960 Set_Do_Length_Check (N, False);
5961 Set_Do_Tag_Check (N, False);
5962 Set_Do_Overflow_Check (N, False);
5971 -- Start of processing for Remove_Checks
5977 ----------------------------
5978 -- Selected_Length_Checks --
5979 ----------------------------
5981 function Selected_Length_Checks
5983 Target_Typ : Entity_Id;
5984 Source_Typ : Entity_Id;
5985 Warn_Node : Node_Id) return Check_Result
5987 Loc : constant Source_Ptr := Sloc (Ck_Node);
5990 Expr_Actual : Node_Id;
5992 Cond : Node_Id := Empty;
5993 Do_Access : Boolean := False;
5994 Wnode : Node_Id := Warn_Node;
5995 Ret_Result : Check_Result := (Empty, Empty);
5996 Num_Checks : Natural := 0;
5998 procedure Add_Check (N : Node_Id);
5999 -- Adds the action given to Ret_Result if N is non-Empty
6001 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
6002 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
6003 -- Comments required ???
6005 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
6006 -- True for equal literals and for nodes that denote the same constant
6007 -- entity, even if its value is not a static constant. This includes the
6008 -- case of a discriminal reference within an init proc. Removes some
6009 -- obviously superfluous checks.
6011 function Length_E_Cond
6012 (Exptyp : Entity_Id;
6014 Indx : Nat) return Node_Id;
6015 -- Returns expression to compute:
6016 -- Typ'Length /= Exptyp'Length
6018 function Length_N_Cond
6021 Indx : Nat) return Node_Id;
6022 -- Returns expression to compute:
6023 -- Typ'Length /= Expr'Length
6029 procedure Add_Check (N : Node_Id) is
6033 -- For now, ignore attempt to place more than 2 checks ???
6035 if Num_Checks = 2 then
6039 pragma Assert (Num_Checks <= 1);
6040 Num_Checks := Num_Checks + 1;
6041 Ret_Result (Num_Checks) := N;
6049 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
6050 SE : constant Entity_Id := Scope (E);
6052 E1 : Entity_Id := E;
6055 if Ekind (Scope (E)) = E_Record_Type
6056 and then Has_Discriminants (Scope (E))
6058 N := Build_Discriminal_Subtype_Of_Component (E);
6061 Insert_Action (Ck_Node, N);
6062 E1 := Defining_Identifier (N);
6066 if Ekind (E1) = E_String_Literal_Subtype then
6068 Make_Integer_Literal (Loc,
6069 Intval => String_Literal_Length (E1));
6071 elsif SE /= Standard_Standard
6072 and then Ekind (Scope (SE)) = E_Protected_Type
6073 and then Has_Discriminants (Scope (SE))
6074 and then Has_Completion (Scope (SE))
6075 and then not Inside_Init_Proc
6077 -- If the type whose length is needed is a private component
6078 -- constrained by a discriminant, we must expand the 'Length
6079 -- attribute into an explicit computation, using the discriminal
6080 -- of the current protected operation. This is because the actual
6081 -- type of the prival is constructed after the protected opera-
6082 -- tion has been fully expanded.
6085 Indx_Type : Node_Id;
6088 Do_Expand : Boolean := False;
6091 Indx_Type := First_Index (E);
6093 for J in 1 .. Indx - 1 loop
6094 Next_Index (Indx_Type);
6097 Get_Index_Bounds (Indx_Type, Lo, Hi);
6099 if Nkind (Lo) = N_Identifier
6100 and then Ekind (Entity (Lo)) = E_In_Parameter
6102 Lo := Get_Discriminal (E, Lo);
6106 if Nkind (Hi) = N_Identifier
6107 and then Ekind (Entity (Hi)) = E_In_Parameter
6109 Hi := Get_Discriminal (E, Hi);
6114 if not Is_Entity_Name (Lo) then
6115 Lo := Duplicate_Subexpr_No_Checks (Lo);
6118 if not Is_Entity_Name (Hi) then
6119 Lo := Duplicate_Subexpr_No_Checks (Hi);
6125 Make_Op_Subtract (Loc,
6129 Right_Opnd => Make_Integer_Literal (Loc, 1));
6134 Make_Attribute_Reference (Loc,
6135 Attribute_Name => Name_Length,
6137 New_Occurrence_Of (E1, Loc));
6140 Set_Expressions (N, New_List (
6141 Make_Integer_Literal (Loc, Indx)));
6150 Make_Attribute_Reference (Loc,
6151 Attribute_Name => Name_Length,
6153 New_Occurrence_Of (E1, Loc));
6156 Set_Expressions (N, New_List (
6157 Make_Integer_Literal (Loc, Indx)));
6168 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
6171 Make_Attribute_Reference (Loc,
6172 Attribute_Name => Name_Length,
6174 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6175 Expressions => New_List (
6176 Make_Integer_Literal (Loc, Indx)));
6183 function Length_E_Cond
6184 (Exptyp : Entity_Id;
6186 Indx : Nat) return Node_Id
6191 Left_Opnd => Get_E_Length (Typ, Indx),
6192 Right_Opnd => Get_E_Length (Exptyp, Indx));
6199 function Length_N_Cond
6202 Indx : Nat) return Node_Id
6207 Left_Opnd => Get_E_Length (Typ, Indx),
6208 Right_Opnd => Get_N_Length (Expr, Indx));
6215 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
6218 (Nkind (L) = N_Integer_Literal
6219 and then Nkind (R) = N_Integer_Literal
6220 and then Intval (L) = Intval (R))
6224 and then Ekind (Entity (L)) = E_Constant
6225 and then ((Is_Entity_Name (R)
6226 and then Entity (L) = Entity (R))
6228 (Nkind (R) = N_Type_Conversion
6229 and then Is_Entity_Name (Expression (R))
6230 and then Entity (L) = Entity (Expression (R)))))
6234 and then Ekind (Entity (R)) = E_Constant
6235 and then Nkind (L) = N_Type_Conversion
6236 and then Is_Entity_Name (Expression (L))
6237 and then Entity (R) = Entity (Expression (L)))
6241 and then Is_Entity_Name (R)
6242 and then Entity (L) = Entity (R)
6243 and then Ekind (Entity (L)) = E_In_Parameter
6244 and then Inside_Init_Proc);
6247 -- Start of processing for Selected_Length_Checks
6250 if not Full_Expander_Active then
6254 if Target_Typ = Any_Type
6255 or else Target_Typ = Any_Composite
6256 or else Raises_Constraint_Error (Ck_Node)
6265 T_Typ := Target_Typ;
6267 if No (Source_Typ) then
6268 S_Typ := Etype (Ck_Node);
6270 S_Typ := Source_Typ;
6273 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6277 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6278 S_Typ := Designated_Type (S_Typ);
6279 T_Typ := Designated_Type (T_Typ);
6282 -- A simple optimization for the null case
6284 if Known_Null (Ck_Node) then
6289 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6290 if Is_Constrained (T_Typ) then
6292 -- The checking code to be generated will freeze the
6293 -- corresponding array type. However, we must freeze the
6294 -- type now, so that the freeze node does not appear within
6295 -- the generated conditional expression, but ahead of it.
6297 Freeze_Before (Ck_Node, T_Typ);
6299 Expr_Actual := Get_Referenced_Object (Ck_Node);
6300 Exptyp := Get_Actual_Subtype (Ck_Node);
6302 if Is_Access_Type (Exptyp) then
6303 Exptyp := Designated_Type (Exptyp);
6306 -- String_Literal case. This needs to be handled specially be-
6307 -- cause no index types are available for string literals. The
6308 -- condition is simply:
6310 -- T_Typ'Length = string-literal-length
6312 if Nkind (Expr_Actual) = N_String_Literal
6313 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
6317 Left_Opnd => Get_E_Length (T_Typ, 1),
6319 Make_Integer_Literal (Loc,
6321 String_Literal_Length (Etype (Expr_Actual))));
6323 -- General array case. Here we have a usable actual subtype for
6324 -- the expression, and the condition is built from the two types
6327 -- T_Typ'Length /= Exptyp'Length or else
6328 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
6329 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
6332 elsif Is_Constrained (Exptyp) then
6334 Ndims : constant Nat := Number_Dimensions (T_Typ);
6347 -- At the library level, we need to ensure that the type of
6348 -- the object is elaborated before the check itself is
6349 -- emitted. This is only done if the object is in the
6350 -- current compilation unit, otherwise the type is frozen
6351 -- and elaborated in its unit.
6353 if Is_Itype (Exptyp)
6355 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
6357 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
6358 and then In_Open_Scopes (Scope (Exptyp))
6360 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
6361 Set_Itype (Ref_Node, Exptyp);
6362 Insert_Action (Ck_Node, Ref_Node);
6365 L_Index := First_Index (T_Typ);
6366 R_Index := First_Index (Exptyp);
6368 for Indx in 1 .. Ndims loop
6369 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6371 Nkind (R_Index) = N_Raise_Constraint_Error)
6373 Get_Index_Bounds (L_Index, L_Low, L_High);
6374 Get_Index_Bounds (R_Index, R_Low, R_High);
6376 -- Deal with compile time length check. Note that we
6377 -- skip this in the access case, because the access
6378 -- value may be null, so we cannot know statically.
6381 and then Compile_Time_Known_Value (L_Low)
6382 and then Compile_Time_Known_Value (L_High)
6383 and then Compile_Time_Known_Value (R_Low)
6384 and then Compile_Time_Known_Value (R_High)
6386 if Expr_Value (L_High) >= Expr_Value (L_Low) then
6387 L_Length := Expr_Value (L_High) -
6388 Expr_Value (L_Low) + 1;
6390 L_Length := UI_From_Int (0);
6393 if Expr_Value (R_High) >= Expr_Value (R_Low) then
6394 R_Length := Expr_Value (R_High) -
6395 Expr_Value (R_Low) + 1;
6397 R_Length := UI_From_Int (0);
6400 if L_Length > R_Length then
6402 (Compile_Time_Constraint_Error
6403 (Wnode, "too few elements for}?", T_Typ));
6405 elsif L_Length < R_Length then
6407 (Compile_Time_Constraint_Error
6408 (Wnode, "too many elements for}?", T_Typ));
6411 -- The comparison for an individual index subtype
6412 -- is omitted if the corresponding index subtypes
6413 -- statically match, since the result is known to
6414 -- be true. Note that this test is worth while even
6415 -- though we do static evaluation, because non-static
6416 -- subtypes can statically match.
6419 Subtypes_Statically_Match
6420 (Etype (L_Index), Etype (R_Index))
6423 (Same_Bounds (L_Low, R_Low)
6424 and then Same_Bounds (L_High, R_High))
6427 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
6436 -- Handle cases where we do not get a usable actual subtype that
6437 -- is constrained. This happens for example in the function call
6438 -- and explicit dereference cases. In these cases, we have to get
6439 -- the length or range from the expression itself, making sure we
6440 -- do not evaluate it more than once.
6442 -- Here Ck_Node is the original expression, or more properly the
6443 -- result of applying Duplicate_Expr to the original tree, forcing
6444 -- the result to be a name.
6448 Ndims : constant Nat := Number_Dimensions (T_Typ);
6451 -- Build the condition for the explicit dereference case
6453 for Indx in 1 .. Ndims loop
6455 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
6462 -- Construct the test and insert into the tree
6464 if Present (Cond) then
6466 Cond := Guard_Access (Cond, Loc, Ck_Node);
6470 (Make_Raise_Constraint_Error (Loc,
6472 Reason => CE_Length_Check_Failed));
6476 end Selected_Length_Checks;
6478 ---------------------------
6479 -- Selected_Range_Checks --
6480 ---------------------------
6482 function Selected_Range_Checks
6484 Target_Typ : Entity_Id;
6485 Source_Typ : Entity_Id;
6486 Warn_Node : Node_Id) return Check_Result
6488 Loc : constant Source_Ptr := Sloc (Ck_Node);
6491 Expr_Actual : Node_Id;
6493 Cond : Node_Id := Empty;
6494 Do_Access : Boolean := False;
6495 Wnode : Node_Id := Warn_Node;
6496 Ret_Result : Check_Result := (Empty, Empty);
6497 Num_Checks : Integer := 0;
6499 procedure Add_Check (N : Node_Id);
6500 -- Adds the action given to Ret_Result if N is non-Empty
6502 function Discrete_Range_Cond
6504 Typ : Entity_Id) return Node_Id;
6505 -- Returns expression to compute:
6506 -- Low_Bound (Expr) < Typ'First
6508 -- High_Bound (Expr) > Typ'Last
6510 function Discrete_Expr_Cond
6512 Typ : Entity_Id) return Node_Id;
6513 -- Returns expression to compute:
6518 function Get_E_First_Or_Last
6522 Nam : Name_Id) return Node_Id;
6523 -- Returns an attribute reference
6524 -- E'First or E'Last
6525 -- with a source location of Loc.
6527 -- Nam is Name_First or Name_Last, according to which attribute is
6528 -- desired. If Indx is non-zero, it is passed as a literal in the
6529 -- Expressions of the attribute reference (identifying the desired
6530 -- array dimension).
6532 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
6533 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
6534 -- Returns expression to compute:
6535 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
6537 function Range_E_Cond
6538 (Exptyp : Entity_Id;
6542 -- Returns expression to compute:
6543 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
6545 function Range_Equal_E_Cond
6546 (Exptyp : Entity_Id;
6548 Indx : Nat) return Node_Id;
6549 -- Returns expression to compute:
6550 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
6552 function Range_N_Cond
6555 Indx : Nat) return Node_Id;
6556 -- Return expression to compute:
6557 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
6563 procedure Add_Check (N : Node_Id) is
6567 -- For now, ignore attempt to place more than 2 checks ???
6569 if Num_Checks = 2 then
6573 pragma Assert (Num_Checks <= 1);
6574 Num_Checks := Num_Checks + 1;
6575 Ret_Result (Num_Checks) := N;
6579 -------------------------
6580 -- Discrete_Expr_Cond --
6581 -------------------------
6583 function Discrete_Expr_Cond
6585 Typ : Entity_Id) return Node_Id
6593 Convert_To (Base_Type (Typ),
6594 Duplicate_Subexpr_No_Checks (Expr)),
6596 Convert_To (Base_Type (Typ),
6597 Get_E_First_Or_Last (Loc, Typ, 0, Name_First))),
6602 Convert_To (Base_Type (Typ),
6603 Duplicate_Subexpr_No_Checks (Expr)),
6607 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last))));
6608 end Discrete_Expr_Cond;
6610 -------------------------
6611 -- Discrete_Range_Cond --
6612 -------------------------
6614 function Discrete_Range_Cond
6616 Typ : Entity_Id) return Node_Id
6618 LB : Node_Id := Low_Bound (Expr);
6619 HB : Node_Id := High_Bound (Expr);
6621 Left_Opnd : Node_Id;
6622 Right_Opnd : Node_Id;
6625 if Nkind (LB) = N_Identifier
6626 and then Ekind (Entity (LB)) = E_Discriminant
6628 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6631 if Nkind (HB) = N_Identifier
6632 and then Ekind (Entity (HB)) = E_Discriminant
6634 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6641 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
6646 Get_E_First_Or_Last (Loc, Typ, 0, Name_First)));
6648 if Base_Type (Typ) = Typ then
6651 elsif Compile_Time_Known_Value (High_Bound (Scalar_Range (Typ)))
6653 Compile_Time_Known_Value (High_Bound (Scalar_Range
6656 if Is_Floating_Point_Type (Typ) then
6657 if Expr_Value_R (High_Bound (Scalar_Range (Typ))) =
6658 Expr_Value_R (High_Bound (Scalar_Range (Base_Type (Typ))))
6664 if Expr_Value (High_Bound (Scalar_Range (Typ))) =
6665 Expr_Value (High_Bound (Scalar_Range (Base_Type (Typ))))
6676 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
6681 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last)));
6683 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
6684 end Discrete_Range_Cond;
6686 -------------------------
6687 -- Get_E_First_Or_Last --
6688 -------------------------
6690 function Get_E_First_Or_Last
6694 Nam : Name_Id) return Node_Id
6699 Exprs := New_List (Make_Integer_Literal (Loc, UI_From_Int (Indx)));
6704 return Make_Attribute_Reference (Loc,
6705 Prefix => New_Occurrence_Of (E, Loc),
6706 Attribute_Name => Nam,
6707 Expressions => Exprs);
6708 end Get_E_First_Or_Last;
6714 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
6717 Make_Attribute_Reference (Loc,
6718 Attribute_Name => Name_First,
6720 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6721 Expressions => New_List (
6722 Make_Integer_Literal (Loc, Indx)));
6729 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
6732 Make_Attribute_Reference (Loc,
6733 Attribute_Name => Name_Last,
6735 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6736 Expressions => New_List (
6737 Make_Integer_Literal (Loc, Indx)));
6744 function Range_E_Cond
6745 (Exptyp : Entity_Id;
6747 Indx : Nat) return Node_Id
6755 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
6757 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
6762 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
6764 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
6767 ------------------------
6768 -- Range_Equal_E_Cond --
6769 ------------------------
6771 function Range_Equal_E_Cond
6772 (Exptyp : Entity_Id;
6774 Indx : Nat) return Node_Id
6782 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
6784 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
6789 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
6791 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
6792 end Range_Equal_E_Cond;
6798 function Range_N_Cond
6801 Indx : Nat) return Node_Id
6809 Get_N_First (Expr, Indx),
6811 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
6816 Get_N_Last (Expr, Indx),
6818 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
6821 -- Start of processing for Selected_Range_Checks
6824 if not Full_Expander_Active then
6828 if Target_Typ = Any_Type
6829 or else Target_Typ = Any_Composite
6830 or else Raises_Constraint_Error (Ck_Node)
6839 T_Typ := Target_Typ;
6841 if No (Source_Typ) then
6842 S_Typ := Etype (Ck_Node);
6844 S_Typ := Source_Typ;
6847 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6851 -- The order of evaluating T_Typ before S_Typ seems to be critical
6852 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
6853 -- in, and since Node can be an N_Range node, it might be invalid.
6854 -- Should there be an assert check somewhere for taking the Etype of
6855 -- an N_Range node ???
6857 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6858 S_Typ := Designated_Type (S_Typ);
6859 T_Typ := Designated_Type (T_Typ);
6862 -- A simple optimization for the null case
6864 if Known_Null (Ck_Node) then
6869 -- For an N_Range Node, check for a null range and then if not
6870 -- null generate a range check action.
6872 if Nkind (Ck_Node) = N_Range then
6874 -- There's no point in checking a range against itself
6876 if Ck_Node = Scalar_Range (T_Typ) then
6881 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
6882 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
6883 Known_T_LB : constant Boolean := Compile_Time_Known_Value (T_LB);
6884 Known_T_HB : constant Boolean := Compile_Time_Known_Value (T_HB);
6886 LB : Node_Id := Low_Bound (Ck_Node);
6887 HB : Node_Id := High_Bound (Ck_Node);
6891 Null_Range : Boolean;
6892 Out_Of_Range_L : Boolean;
6893 Out_Of_Range_H : Boolean;
6896 -- Compute what is known at compile time
6898 if Known_T_LB and Known_T_HB then
6899 if Compile_Time_Known_Value (LB) then
6902 -- There's no point in checking that a bound is within its
6903 -- own range so pretend that it is known in this case. First
6904 -- deal with low bound.
6906 elsif Ekind (Etype (LB)) = E_Signed_Integer_Subtype
6907 and then Scalar_Range (Etype (LB)) = Scalar_Range (T_Typ)
6916 -- Likewise for the high bound
6918 if Compile_Time_Known_Value (HB) then
6921 elsif Ekind (Etype (HB)) = E_Signed_Integer_Subtype
6922 and then Scalar_Range (Etype (HB)) = Scalar_Range (T_Typ)
6932 -- Check for case where everything is static and we can do the
6933 -- check at compile time. This is skipped if we have an access
6934 -- type, since the access value may be null.
6936 -- ??? This code can be improved since you only need to know that
6937 -- the two respective bounds (LB & T_LB or HB & T_HB) are known at
6938 -- compile time to emit pertinent messages.
6940 if Known_T_LB and Known_T_HB and Known_LB and Known_HB
6943 -- Floating-point case
6945 if Is_Floating_Point_Type (S_Typ) then
6946 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
6948 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
6950 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
6953 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
6955 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
6957 -- Fixed or discrete type case
6960 Null_Range := Expr_Value (HB) < Expr_Value (LB);
6962 (Expr_Value (LB) < Expr_Value (T_LB))
6964 (Expr_Value (LB) > Expr_Value (T_HB));
6967 (Expr_Value (HB) > Expr_Value (T_HB))
6969 (Expr_Value (HB) < Expr_Value (T_LB));
6972 if not Null_Range then
6973 if Out_Of_Range_L then
6974 if No (Warn_Node) then
6976 (Compile_Time_Constraint_Error
6977 (Low_Bound (Ck_Node),
6978 "static value out of range of}?", T_Typ));
6982 (Compile_Time_Constraint_Error
6984 "static range out of bounds of}?", T_Typ));
6988 if Out_Of_Range_H then
6989 if No (Warn_Node) then
6991 (Compile_Time_Constraint_Error
6992 (High_Bound (Ck_Node),
6993 "static value out of range of}?", T_Typ));
6997 (Compile_Time_Constraint_Error
6999 "static range out of bounds of}?", T_Typ));
7006 LB : Node_Id := Low_Bound (Ck_Node);
7007 HB : Node_Id := High_Bound (Ck_Node);
7010 -- If either bound is a discriminant and we are within the
7011 -- record declaration, it is a use of the discriminant in a
7012 -- constraint of a component, and nothing can be checked
7013 -- here. The check will be emitted within the init proc.
7014 -- Before then, the discriminal has no real meaning.
7015 -- Similarly, if the entity is a discriminal, there is no
7016 -- check to perform yet.
7018 -- The same holds within a discriminated synchronized type,
7019 -- where the discriminant may constrain a component or an
7022 if Nkind (LB) = N_Identifier
7023 and then Denotes_Discriminant (LB, True)
7025 if Current_Scope = Scope (Entity (LB))
7026 or else Is_Concurrent_Type (Current_Scope)
7027 or else Ekind (Entity (LB)) /= E_Discriminant
7032 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
7036 if Nkind (HB) = N_Identifier
7037 and then Denotes_Discriminant (HB, True)
7039 if Current_Scope = Scope (Entity (HB))
7040 or else Is_Concurrent_Type (Current_Scope)
7041 or else Ekind (Entity (HB)) /= E_Discriminant
7046 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
7050 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
7051 Set_Paren_Count (Cond, 1);
7057 Left_Opnd => Duplicate_Subexpr_No_Checks (HB),
7058 Right_Opnd => Duplicate_Subexpr_No_Checks (LB)),
7059 Right_Opnd => Cond);
7064 elsif Is_Scalar_Type (S_Typ) then
7066 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
7067 -- except the above simply sets a flag in the node and lets
7068 -- gigi generate the check base on the Etype of the expression.
7069 -- Sometimes, however we want to do a dynamic check against an
7070 -- arbitrary target type, so we do that here.
7072 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
7073 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
7075 -- For literals, we can tell if the constraint error will be
7076 -- raised at compile time, so we never need a dynamic check, but
7077 -- if the exception will be raised, then post the usual warning,
7078 -- and replace the literal with a raise constraint error
7079 -- expression. As usual, skip this for access types
7081 elsif Compile_Time_Known_Value (Ck_Node)
7082 and then not Do_Access
7085 LB : constant Node_Id := Type_Low_Bound (T_Typ);
7086 UB : constant Node_Id := Type_High_Bound (T_Typ);
7088 Out_Of_Range : Boolean;
7089 Static_Bounds : constant Boolean :=
7090 Compile_Time_Known_Value (LB)
7091 and Compile_Time_Known_Value (UB);
7094 -- Following range tests should use Sem_Eval routine ???
7096 if Static_Bounds then
7097 if Is_Floating_Point_Type (S_Typ) then
7099 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
7101 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
7103 -- Fixed or discrete type
7107 Expr_Value (Ck_Node) < Expr_Value (LB)
7109 Expr_Value (Ck_Node) > Expr_Value (UB);
7112 -- Bounds of the type are static and the literal is out of
7113 -- range so output a warning message.
7115 if Out_Of_Range then
7116 if No (Warn_Node) then
7118 (Compile_Time_Constraint_Error
7120 "static value out of range of}?", T_Typ));
7124 (Compile_Time_Constraint_Error
7126 "static value out of range of}?", T_Typ));
7131 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
7135 -- Here for the case of a non-static expression, we need a runtime
7136 -- check unless the source type range is guaranteed to be in the
7137 -- range of the target type.
7140 if not In_Subrange_Of (S_Typ, T_Typ) then
7141 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
7146 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
7147 if Is_Constrained (T_Typ) then
7149 Expr_Actual := Get_Referenced_Object (Ck_Node);
7150 Exptyp := Get_Actual_Subtype (Expr_Actual);
7152 if Is_Access_Type (Exptyp) then
7153 Exptyp := Designated_Type (Exptyp);
7156 -- String_Literal case. This needs to be handled specially be-
7157 -- cause no index types are available for string literals. The
7158 -- condition is simply:
7160 -- T_Typ'Length = string-literal-length
7162 if Nkind (Expr_Actual) = N_String_Literal then
7165 -- General array case. Here we have a usable actual subtype for
7166 -- the expression, and the condition is built from the two types
7168 -- T_Typ'First < Exptyp'First or else
7169 -- T_Typ'Last > Exptyp'Last or else
7170 -- T_Typ'First(1) < Exptyp'First(1) or else
7171 -- T_Typ'Last(1) > Exptyp'Last(1) or else
7174 elsif Is_Constrained (Exptyp) then
7176 Ndims : constant Nat := Number_Dimensions (T_Typ);
7182 L_Index := First_Index (T_Typ);
7183 R_Index := First_Index (Exptyp);
7185 for Indx in 1 .. Ndims loop
7186 if not (Nkind (L_Index) = N_Raise_Constraint_Error
7188 Nkind (R_Index) = N_Raise_Constraint_Error)
7190 -- Deal with compile time length check. Note that we
7191 -- skip this in the access case, because the access
7192 -- value may be null, so we cannot know statically.
7195 Subtypes_Statically_Match
7196 (Etype (L_Index), Etype (R_Index))
7198 -- If the target type is constrained then we
7199 -- have to check for exact equality of bounds
7200 -- (required for qualified expressions).
7202 if Is_Constrained (T_Typ) then
7205 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
7208 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
7218 -- Handle cases where we do not get a usable actual subtype that
7219 -- is constrained. This happens for example in the function call
7220 -- and explicit dereference cases. In these cases, we have to get
7221 -- the length or range from the expression itself, making sure we
7222 -- do not evaluate it more than once.
7224 -- Here Ck_Node is the original expression, or more properly the
7225 -- result of applying Duplicate_Expr to the original tree,
7226 -- forcing the result to be a name.
7230 Ndims : constant Nat := Number_Dimensions (T_Typ);
7233 -- Build the condition for the explicit dereference case
7235 for Indx in 1 .. Ndims loop
7237 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
7243 -- For a conversion to an unconstrained array type, generate an
7244 -- Action to check that the bounds of the source value are within
7245 -- the constraints imposed by the target type (RM 4.6(38)). No
7246 -- check is needed for a conversion to an access to unconstrained
7247 -- array type, as 4.6(24.15/2) requires the designated subtypes
7248 -- of the two access types to statically match.
7250 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
7251 and then not Do_Access
7254 Opnd_Index : Node_Id;
7255 Targ_Index : Node_Id;
7256 Opnd_Range : Node_Id;
7259 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
7260 Targ_Index := First_Index (T_Typ);
7261 while Present (Opnd_Index) loop
7263 -- If the index is a range, use its bounds. If it is an
7264 -- entity (as will be the case if it is a named subtype
7265 -- or an itype created for a slice) retrieve its range.
7267 if Is_Entity_Name (Opnd_Index)
7268 and then Is_Type (Entity (Opnd_Index))
7270 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
7272 Opnd_Range := Opnd_Index;
7275 if Nkind (Opnd_Range) = N_Range then
7277 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7278 Assume_Valid => True)
7281 (High_Bound (Opnd_Range), Etype (Targ_Index),
7282 Assume_Valid => True)
7286 -- If null range, no check needed
7289 Compile_Time_Known_Value (High_Bound (Opnd_Range))
7291 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
7293 Expr_Value (High_Bound (Opnd_Range)) <
7294 Expr_Value (Low_Bound (Opnd_Range))
7298 elsif Is_Out_Of_Range
7299 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7300 Assume_Valid => True)
7303 (High_Bound (Opnd_Range), Etype (Targ_Index),
7304 Assume_Valid => True)
7307 (Compile_Time_Constraint_Error
7308 (Wnode, "value out of range of}?", T_Typ));
7314 (Opnd_Range, Etype (Targ_Index)));
7318 Next_Index (Opnd_Index);
7319 Next_Index (Targ_Index);
7326 -- Construct the test and insert into the tree
7328 if Present (Cond) then
7330 Cond := Guard_Access (Cond, Loc, Ck_Node);
7334 (Make_Raise_Constraint_Error (Loc,
7336 Reason => CE_Range_Check_Failed));
7340 end Selected_Range_Checks;
7342 -------------------------------
7343 -- Storage_Checks_Suppressed --
7344 -------------------------------
7346 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
7348 if Present (E) and then Checks_May_Be_Suppressed (E) then
7349 return Is_Check_Suppressed (E, Storage_Check);
7351 return Scope_Suppress (Storage_Check);
7353 end Storage_Checks_Suppressed;
7355 ---------------------------
7356 -- Tag_Checks_Suppressed --
7357 ---------------------------
7359 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
7362 if Kill_Tag_Checks (E) then
7364 elsif Checks_May_Be_Suppressed (E) then
7365 return Is_Check_Suppressed (E, Tag_Check);
7369 return Scope_Suppress (Tag_Check);
7370 end Tag_Checks_Suppressed;
7372 --------------------------
7373 -- Validity_Check_Range --
7374 --------------------------
7376 procedure Validity_Check_Range (N : Node_Id) is
7378 if Validity_Checks_On and Validity_Check_Operands then
7379 if Nkind (N) = N_Range then
7380 Ensure_Valid (Low_Bound (N));
7381 Ensure_Valid (High_Bound (N));
7384 end Validity_Check_Range;
7386 --------------------------------
7387 -- Validity_Checks_Suppressed --
7388 --------------------------------
7390 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
7392 if Present (E) and then Checks_May_Be_Suppressed (E) then
7393 return Is_Check_Suppressed (E, Validity_Check);
7395 return Scope_Suppress (Validity_Check);
7397 end Validity_Checks_Suppressed;