1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Debug; use Debug;
28 with Einfo; use Einfo;
29 with Errout; use Errout;
30 with Exp_Ch2; use Exp_Ch2;
31 with Exp_Ch11; use Exp_Ch11;
32 with Exp_Pakd; use Exp_Pakd;
33 with Exp_Util; use Exp_Util;
34 with Elists; use Elists;
35 with Eval_Fat; use Eval_Fat;
36 with Freeze; use Freeze;
38 with Nlists; use Nlists;
39 with Nmake; use Nmake;
41 with Output; use Output;
42 with Restrict; use Restrict;
43 with Rident; use Rident;
44 with Rtsfind; use Rtsfind;
46 with Sem_Aux; use Sem_Aux;
47 with Sem_Eval; use Sem_Eval;
48 with Sem_Ch3; use Sem_Ch3;
49 with Sem_Ch8; use Sem_Ch8;
50 with Sem_Res; use Sem_Res;
51 with Sem_Util; use Sem_Util;
52 with Sem_Warn; use Sem_Warn;
53 with Sinfo; use Sinfo;
54 with Sinput; use Sinput;
55 with Snames; use Snames;
56 with Sprint; use Sprint;
57 with Stand; use Stand;
58 with Targparm; use Targparm;
59 with Tbuild; use Tbuild;
60 with Ttypes; use Ttypes;
61 with Urealp; use Urealp;
62 with Validsw; use Validsw;
64 package body Checks is
66 -- General note: many of these routines are concerned with generating
67 -- checking code to make sure that constraint error is raised at runtime.
68 -- Clearly this code is only needed if the expander is active, since
69 -- otherwise we will not be generating code or going into the runtime
72 -- We therefore disconnect most of these checks if the expander is
73 -- inactive. This has the additional benefit that we do not need to
74 -- worry about the tree being messed up by previous errors (since errors
75 -- turn off expansion anyway).
77 -- There are a few exceptions to the above rule. For instance routines
78 -- such as Apply_Scalar_Range_Check that do not insert any code can be
79 -- safely called even when the Expander is inactive (but Errors_Detected
80 -- is 0). The benefit of executing this code when expansion is off, is
81 -- the ability to emit constraint error warning for static expressions
82 -- even when we are not generating code.
84 -------------------------------------
85 -- Suppression of Redundant Checks --
86 -------------------------------------
88 -- This unit implements a limited circuit for removal of redundant
89 -- checks. The processing is based on a tracing of simple sequential
90 -- flow. For any sequence of statements, we save expressions that are
91 -- marked to be checked, and then if the same expression appears later
92 -- with the same check, then under certain circumstances, the second
93 -- check can be suppressed.
95 -- Basically, we can suppress the check if we know for certain that
96 -- the previous expression has been elaborated (together with its
97 -- check), and we know that the exception frame is the same, and that
98 -- nothing has happened to change the result of the exception.
100 -- Let us examine each of these three conditions in turn to describe
101 -- how we ensure that this condition is met.
103 -- First, we need to know for certain that the previous expression has
104 -- been executed. This is done principly by the mechanism of calling
105 -- Conditional_Statements_Begin at the start of any statement sequence
106 -- and Conditional_Statements_End at the end. The End call causes all
107 -- checks remembered since the Begin call to be discarded. This does
108 -- miss a few cases, notably the case of a nested BEGIN-END block with
109 -- no exception handlers. But the important thing is to be conservative.
110 -- The other protection is that all checks are discarded if a label
111 -- is encountered, since then the assumption of sequential execution
112 -- is violated, and we don't know enough about the flow.
114 -- Second, we need to know that the exception frame is the same. We
115 -- do this by killing all remembered checks when we enter a new frame.
116 -- Again, that's over-conservative, but generally the cases we can help
117 -- with are pretty local anyway (like the body of a loop for example).
119 -- Third, we must be sure to forget any checks which are no longer valid.
120 -- This is done by two mechanisms, first the Kill_Checks_Variable call is
121 -- used to note any changes to local variables. We only attempt to deal
122 -- with checks involving local variables, so we do not need to worry
123 -- about global variables. Second, a call to any non-global procedure
124 -- causes us to abandon all stored checks, since such a all may affect
125 -- the values of any local variables.
127 -- The following define the data structures used to deal with remembering
128 -- checks so that redundant checks can be eliminated as described above.
130 -- Right now, the only expressions that we deal with are of the form of
131 -- simple local objects (either declared locally, or IN parameters) or
132 -- such objects plus/minus a compile time known constant. We can do
133 -- more later on if it seems worthwhile, but this catches many simple
134 -- cases in practice.
136 -- The following record type reflects a single saved check. An entry
137 -- is made in the stack of saved checks if and only if the expression
138 -- has been elaborated with the indicated checks.
140 type Saved_Check is record
142 -- Set True if entry is killed by Kill_Checks
145 -- The entity involved in the expression that is checked
148 -- A compile time value indicating the result of adding or
149 -- subtracting a compile time value. This value is to be
150 -- added to the value of the Entity. A value of zero is
151 -- used for the case of a simple entity reference.
153 Check_Type : Character;
154 -- This is set to 'R' for a range check (in which case Target_Type
155 -- is set to the target type for the range check) or to 'O' for an
156 -- overflow check (in which case Target_Type is set to Empty).
158 Target_Type : Entity_Id;
159 -- Used only if Do_Range_Check is set. Records the target type for
160 -- the check. We need this, because a check is a duplicate only if
161 -- it has a the same target type (or more accurately one with a
162 -- range that is smaller or equal to the stored target type of a
166 -- The following table keeps track of saved checks. Rather than use an
167 -- extensible table. We just use a table of fixed size, and we discard
168 -- any saved checks that do not fit. That's very unlikely to happen and
169 -- this is only an optimization in any case.
171 Saved_Checks : array (Int range 1 .. 200) of Saved_Check;
172 -- Array of saved checks
174 Num_Saved_Checks : Nat := 0;
175 -- Number of saved checks
177 -- The following stack keeps track of statement ranges. It is treated
178 -- as a stack. When Conditional_Statements_Begin is called, an entry
179 -- is pushed onto this stack containing the value of Num_Saved_Checks
180 -- at the time of the call. Then when Conditional_Statements_End is
181 -- called, this value is popped off and used to reset Num_Saved_Checks.
183 -- Note: again, this is a fixed length stack with a size that should
184 -- always be fine. If the value of the stack pointer goes above the
185 -- limit, then we just forget all saved checks.
187 Saved_Checks_Stack : array (Int range 1 .. 100) of Nat;
188 Saved_Checks_TOS : Nat := 0;
190 -----------------------
191 -- Local Subprograms --
192 -----------------------
194 procedure Apply_Float_Conversion_Check
196 Target_Typ : Entity_Id);
197 -- The checks on a conversion from a floating-point type to an integer
198 -- type are delicate. They have to be performed before conversion, they
199 -- have to raise an exception when the operand is a NaN, and rounding must
200 -- be taken into account to determine the safe bounds of the operand.
202 procedure Apply_Selected_Length_Checks
204 Target_Typ : Entity_Id;
205 Source_Typ : Entity_Id;
206 Do_Static : Boolean);
207 -- This is the subprogram that does all the work for Apply_Length_Check
208 -- and Apply_Static_Length_Check. Expr, Target_Typ and Source_Typ are as
209 -- described for the above routines. The Do_Static flag indicates that
210 -- only a static check is to be done.
212 procedure Apply_Selected_Range_Checks
214 Target_Typ : Entity_Id;
215 Source_Typ : Entity_Id;
216 Do_Static : Boolean);
217 -- This is the subprogram that does all the work for Apply_Range_Check.
218 -- Expr, Target_Typ and Source_Typ are as described for the above
219 -- routine. The Do_Static flag indicates that only a static check is
222 type Check_Type is new Check_Id range Access_Check .. Division_Check;
223 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean;
224 -- This function is used to see if an access or division by zero check is
225 -- needed. The check is to be applied to a single variable appearing in the
226 -- source, and N is the node for the reference. If N is not of this form,
227 -- True is returned with no further processing. If N is of the right form,
228 -- then further processing determines if the given Check is needed.
230 -- The particular circuit is to see if we have the case of a check that is
231 -- not needed because it appears in the right operand of a short circuited
232 -- conditional where the left operand guards the check. For example:
234 -- if Var = 0 or else Q / Var > 12 then
238 -- In this example, the division check is not required. At the same time
239 -- we can issue warnings for suspicious use of non-short-circuited forms,
242 -- if Var = 0 or Q / Var > 12 then
248 Check_Type : Character;
249 Target_Type : Entity_Id;
250 Entry_OK : out Boolean;
254 -- This routine is used by Enable_Range_Check and Enable_Overflow_Check
255 -- to see if a check is of the form for optimization, and if so, to see
256 -- if it has already been performed. Expr is the expression to check,
257 -- and Check_Type is 'R' for a range check, 'O' for an overflow check.
258 -- Target_Type is the target type for a range check, and Empty for an
259 -- overflow check. If the entry is not of the form for optimization,
260 -- then Entry_OK is set to False, and the remaining out parameters
261 -- are undefined. If the entry is OK, then Ent/Ofs are set to the
262 -- entity and offset from the expression. Check_Num is the number of
263 -- a matching saved entry in Saved_Checks, or zero if no such entry
266 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id;
267 -- If a discriminal is used in constraining a prival, Return reference
268 -- to the discriminal of the protected body (which renames the parameter
269 -- of the enclosing protected operation). This clumsy transformation is
270 -- needed because privals are created too late and their actual subtypes
271 -- are not available when analysing the bodies of the protected operations.
272 -- This function is called whenever the bound is an entity and the scope
273 -- indicates a protected operation. If the bound is an in-parameter of
274 -- a protected operation that is not a prival, the function returns the
276 -- To be cleaned up???
278 function Guard_Access
281 Ck_Node : Node_Id) return Node_Id;
282 -- In the access type case, guard the test with a test to ensure
283 -- that the access value is non-null, since the checks do not
284 -- not apply to null access values.
286 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr);
287 -- Called by Apply_{Length,Range}_Checks to rewrite the tree with the
288 -- Constraint_Error node.
290 function Range_Or_Validity_Checks_Suppressed
291 (Expr : Node_Id) return Boolean;
292 -- Returns True if either range or validity checks or both are suppressed
293 -- for the type of the given expression, or, if the expression is the name
294 -- of an entity, if these checks are suppressed for the entity.
296 function Selected_Length_Checks
298 Target_Typ : Entity_Id;
299 Source_Typ : Entity_Id;
300 Warn_Node : Node_Id) return Check_Result;
301 -- Like Apply_Selected_Length_Checks, except it doesn't modify
302 -- anything, just returns a list of nodes as described in the spec of
303 -- this package for the Range_Check function.
305 function Selected_Range_Checks
307 Target_Typ : Entity_Id;
308 Source_Typ : Entity_Id;
309 Warn_Node : Node_Id) return Check_Result;
310 -- Like Apply_Selected_Range_Checks, except it doesn't modify anything,
311 -- just returns a list of nodes as described in the spec of this package
312 -- for the Range_Check function.
314 ------------------------------
315 -- Access_Checks_Suppressed --
316 ------------------------------
318 function Access_Checks_Suppressed (E : Entity_Id) return Boolean is
320 if Present (E) and then Checks_May_Be_Suppressed (E) then
321 return Is_Check_Suppressed (E, Access_Check);
323 return Scope_Suppress (Access_Check);
325 end Access_Checks_Suppressed;
327 -------------------------------------
328 -- Accessibility_Checks_Suppressed --
329 -------------------------------------
331 function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean is
333 if Present (E) and then Checks_May_Be_Suppressed (E) then
334 return Is_Check_Suppressed (E, Accessibility_Check);
336 return Scope_Suppress (Accessibility_Check);
338 end Accessibility_Checks_Suppressed;
340 -----------------------------
341 -- Activate_Division_Check --
342 -----------------------------
344 procedure Activate_Division_Check (N : Node_Id) is
346 Set_Do_Division_Check (N, True);
347 Possible_Local_Raise (N, Standard_Constraint_Error);
348 end Activate_Division_Check;
350 -----------------------------
351 -- Activate_Overflow_Check --
352 -----------------------------
354 procedure Activate_Overflow_Check (N : Node_Id) is
356 Set_Do_Overflow_Check (N, True);
357 Possible_Local_Raise (N, Standard_Constraint_Error);
358 end Activate_Overflow_Check;
360 --------------------------
361 -- Activate_Range_Check --
362 --------------------------
364 procedure Activate_Range_Check (N : Node_Id) is
366 Set_Do_Range_Check (N, True);
367 Possible_Local_Raise (N, Standard_Constraint_Error);
368 end Activate_Range_Check;
370 ---------------------------------
371 -- Alignment_Checks_Suppressed --
372 ---------------------------------
374 function Alignment_Checks_Suppressed (E : Entity_Id) return Boolean is
376 if Present (E) and then Checks_May_Be_Suppressed (E) then
377 return Is_Check_Suppressed (E, Alignment_Check);
379 return Scope_Suppress (Alignment_Check);
381 end Alignment_Checks_Suppressed;
383 -------------------------
384 -- Append_Range_Checks --
385 -------------------------
387 procedure Append_Range_Checks
388 (Checks : Check_Result;
390 Suppress_Typ : Entity_Id;
391 Static_Sloc : Source_Ptr;
394 Internal_Flag_Node : constant Node_Id := Flag_Node;
395 Internal_Static_Sloc : constant Source_Ptr := Static_Sloc;
397 Checks_On : constant Boolean :=
398 (not Index_Checks_Suppressed (Suppress_Typ))
400 (not Range_Checks_Suppressed (Suppress_Typ));
403 -- For now we just return if Checks_On is false, however this should
404 -- be enhanced to check for an always True value in the condition
405 -- and to generate a compilation warning???
407 if not Checks_On then
412 exit when No (Checks (J));
414 if Nkind (Checks (J)) = N_Raise_Constraint_Error
415 and then Present (Condition (Checks (J)))
417 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
418 Append_To (Stmts, Checks (J));
419 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
425 Make_Raise_Constraint_Error (Internal_Static_Sloc,
426 Reason => CE_Range_Check_Failed));
429 end Append_Range_Checks;
431 ------------------------
432 -- Apply_Access_Check --
433 ------------------------
435 procedure Apply_Access_Check (N : Node_Id) is
436 P : constant Node_Id := Prefix (N);
439 -- We do not need checks if we are not generating code (i.e. the
440 -- expander is not active). This is not just an optimization, there
441 -- are cases (e.g. with pragma Debug) where generating the checks
442 -- can cause real trouble).
444 if not Expander_Active then
448 -- No check if short circuiting makes check unnecessary
450 if not Check_Needed (P, Access_Check) then
454 -- No check if accessing the Offset_To_Top component of a dispatch
455 -- table. They are safe by construction.
457 if Present (Etype (P))
458 and then RTU_Loaded (Ada_Tags)
459 and then RTE_Available (RE_Offset_To_Top_Ptr)
460 and then Etype (P) = RTE (RE_Offset_To_Top_Ptr)
465 -- Otherwise go ahead and install the check
467 Install_Null_Excluding_Check (P);
468 end Apply_Access_Check;
470 -------------------------------
471 -- Apply_Accessibility_Check --
472 -------------------------------
474 procedure Apply_Accessibility_Check
477 Insert_Node : Node_Id)
479 Loc : constant Source_Ptr := Sloc (N);
480 Param_Ent : constant Entity_Id := Param_Entity (N);
481 Param_Level : Node_Id;
482 Type_Level : Node_Id;
485 if Inside_A_Generic then
488 -- Only apply the run-time check if the access parameter
489 -- has an associated extra access level parameter and
490 -- when the level of the type is less deep than the level
491 -- of the access parameter.
493 elsif Present (Param_Ent)
494 and then Present (Extra_Accessibility (Param_Ent))
495 and then UI_Gt (Object_Access_Level (N),
496 Type_Access_Level (Typ))
497 and then not Accessibility_Checks_Suppressed (Param_Ent)
498 and then not Accessibility_Checks_Suppressed (Typ)
501 New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc);
504 Make_Integer_Literal (Loc, Type_Access_Level (Typ));
506 -- Raise Program_Error if the accessibility level of the access
507 -- parameter is deeper than the level of the target access type.
509 Insert_Action (Insert_Node,
510 Make_Raise_Program_Error (Loc,
513 Left_Opnd => Param_Level,
514 Right_Opnd => Type_Level),
515 Reason => PE_Accessibility_Check_Failed));
517 Analyze_And_Resolve (N);
519 end Apply_Accessibility_Check;
521 --------------------------------
522 -- Apply_Address_Clause_Check --
523 --------------------------------
525 procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is
526 AC : constant Node_Id := Address_Clause (E);
527 Loc : constant Source_Ptr := Sloc (AC);
528 Typ : constant Entity_Id := Etype (E);
529 Aexp : constant Node_Id := Expression (AC);
532 -- Address expression (not necessarily the same as Aexp, for example
533 -- when Aexp is a reference to a constant, in which case Expr gets
534 -- reset to reference the value expression of the constant.
536 Size_Warning_Output : Boolean := False;
537 -- If we output a size warning we set this True, to stop generating
538 -- what is likely to be an unuseful redundant alignment warning.
540 procedure Compile_Time_Bad_Alignment;
541 -- Post error warnings when alignment is known to be incompatible. Note
542 -- that we do not go as far as inserting a raise of Program_Error since
543 -- this is an erroneous case, and it may happen that we are lucky and an
544 -- underaligned address turns out to be OK after all. Also this warning
545 -- is suppressed if we already complained about the size.
547 --------------------------------
548 -- Compile_Time_Bad_Alignment --
549 --------------------------------
551 procedure Compile_Time_Bad_Alignment is
553 if not Size_Warning_Output
554 and then Address_Clause_Overlay_Warnings
557 ("?specified address for& may be inconsistent with alignment ",
560 ("\?program execution may be erroneous (RM 13.3(27))",
562 Set_Address_Warning_Posted (AC);
564 end Compile_Time_Bad_Alignment;
566 -- Start of processing for Apply_Address_Clause_Check
569 -- First obtain expression from address clause
571 Expr := Expression (AC);
573 -- The following loop digs for the real expression to use in the check
576 -- For constant, get constant expression
578 if Is_Entity_Name (Expr)
579 and then Ekind (Entity (Expr)) = E_Constant
581 Expr := Constant_Value (Entity (Expr));
583 -- For unchecked conversion, get result to convert
585 elsif Nkind (Expr) = N_Unchecked_Type_Conversion then
586 Expr := Expression (Expr);
588 -- For (common case) of To_Address call, get argument
590 elsif Nkind (Expr) = N_Function_Call
591 and then Is_Entity_Name (Name (Expr))
592 and then Is_RTE (Entity (Name (Expr)), RE_To_Address)
594 Expr := First (Parameter_Associations (Expr));
596 if Nkind (Expr) = N_Parameter_Association then
597 Expr := Explicit_Actual_Parameter (Expr);
600 -- We finally have the real expression
607 -- Output a warning if we have the situation of
609 -- for X'Address use Y'Address
611 -- and X and Y both have known object sizes, and Y is smaller than X
613 if Nkind (Expr) = N_Attribute_Reference
614 and then Attribute_Name (Expr) = Name_Address
615 and then Is_Entity_Name (Prefix (Expr))
618 Exp_Ent : constant Entity_Id := Entity (Prefix (Expr));
619 Obj_Size : Uint := No_Uint;
620 Exp_Size : Uint := No_Uint;
623 if Known_Esize (E) then
624 Obj_Size := Esize (E);
625 elsif Known_Esize (Etype (E)) then
626 Obj_Size := Esize (Etype (E));
629 if Known_Esize (Exp_Ent) then
630 Exp_Size := Esize (Exp_Ent);
631 elsif Known_Esize (Etype (Exp_Ent)) then
632 Exp_Size := Esize (Etype (Exp_Ent));
635 if Obj_Size /= No_Uint
636 and then Exp_Size /= No_Uint
637 and then Obj_Size > Exp_Size
638 and then not Has_Warnings_Off (E)
640 if Address_Clause_Overlay_Warnings then
642 ("?& overlays smaller object", Aexp, E);
644 ("\?program execution may be erroneous", Aexp, E);
645 Size_Warning_Output := True;
646 Set_Address_Warning_Posted (AC);
652 -- See if alignment check needed. Note that we never need a check if the
653 -- maximum alignment is one, since the check will always succeed.
655 -- Note: we do not check for checks suppressed here, since that check
656 -- was done in Sem_Ch13 when the address clause was processed. We are
657 -- only called if checks were not suppressed. The reason for this is
658 -- that we have to delay the call to Apply_Alignment_Check till freeze
659 -- time (so that all types etc are elaborated), but we have to check
660 -- the status of check suppressing at the point of the address clause.
663 or else not Check_Address_Alignment (AC)
664 or else Maximum_Alignment = 1
669 -- See if we know that Expr is a bad alignment at compile time
671 if Compile_Time_Known_Value (Expr)
672 and then (Known_Alignment (E) or else Known_Alignment (Typ))
675 AL : Uint := Alignment (Typ);
678 -- The object alignment might be more restrictive than the
681 if Known_Alignment (E) then
685 if Expr_Value (Expr) mod AL /= 0 then
686 Compile_Time_Bad_Alignment;
692 -- If the expression has the form X'Address, then we can find out if
693 -- the object X has an alignment that is compatible with the object E.
695 elsif Nkind (Expr) = N_Attribute_Reference
696 and then Attribute_Name (Expr) = Name_Address
699 AR : constant Alignment_Result :=
700 Has_Compatible_Alignment (E, Prefix (Expr));
702 if AR = Known_Compatible then
704 elsif AR = Known_Incompatible then
705 Compile_Time_Bad_Alignment;
710 -- Here we do not know if the value is acceptable. Stricly we don't have
711 -- to do anything, since if the alignment is bad, we have an erroneous
712 -- program. However we are allowed to check for erroneous conditions and
713 -- we decide to do this by default if the check is not suppressed.
715 -- However, don't do the check if elaboration code is unwanted
717 if Restriction_Active (No_Elaboration_Code) then
720 -- Generate a check to raise PE if alignment may be inappropriate
723 -- If the original expression is a non-static constant, use the
724 -- name of the constant itself rather than duplicating its
725 -- defining expression, which was extracted above.
727 -- Note: Expr is empty if the address-clause is applied to in-mode
728 -- actuals (allowed by 13.1(22)).
730 if not Present (Expr)
732 (Is_Entity_Name (Expression (AC))
733 and then Ekind (Entity (Expression (AC))) = E_Constant
734 and then Nkind (Parent (Entity (Expression (AC))))
735 = N_Object_Declaration)
737 Expr := New_Copy_Tree (Expression (AC));
739 Remove_Side_Effects (Expr);
742 Insert_After_And_Analyze (N,
743 Make_Raise_Program_Error (Loc,
750 (RTE (RE_Integer_Address), Expr),
752 Make_Attribute_Reference (Loc,
753 Prefix => New_Occurrence_Of (E, Loc),
754 Attribute_Name => Name_Alignment)),
755 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
756 Reason => PE_Misaligned_Address_Value),
757 Suppress => All_Checks);
762 -- If we have some missing run time component in configurable run time
763 -- mode then just skip the check (it is not required in any case).
765 when RE_Not_Available =>
767 end Apply_Address_Clause_Check;
769 -------------------------------------
770 -- Apply_Arithmetic_Overflow_Check --
771 -------------------------------------
773 -- This routine is called only if the type is an integer type, and a
774 -- software arithmetic overflow check may be needed for op (add, subtract,
775 -- or multiply). This check is performed only if Software_Overflow_Checking
776 -- is enabled and Do_Overflow_Check is set. In this case we expand the
777 -- operation into a more complex sequence of tests that ensures that
778 -- overflow is properly caught.
780 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
781 Loc : constant Source_Ptr := Sloc (N);
782 Typ : Entity_Id := Etype (N);
783 Rtyp : Entity_Id := Root_Type (Typ);
786 -- An interesting special case. If the arithmetic operation appears as
787 -- the operand of a type conversion:
791 -- and all the following conditions apply:
793 -- arithmetic operation is for a signed integer type
794 -- target type type1 is a static integer subtype
795 -- range of x and y are both included in the range of type1
796 -- range of x op y is included in the range of type1
797 -- size of type1 is at least twice the result size of op
799 -- then we don't do an overflow check in any case, instead we transform
800 -- the operation so that we end up with:
802 -- type1 (type1 (x) op type1 (y))
804 -- This avoids intermediate overflow before the conversion. It is
805 -- explicitly permitted by RM 3.5.4(24):
807 -- For the execution of a predefined operation of a signed integer
808 -- type, the implementation need not raise Constraint_Error if the
809 -- result is outside the base range of the type, so long as the
810 -- correct result is produced.
812 -- It's hard to imagine that any programmer counts on the exception
813 -- being raised in this case, and in any case it's wrong coding to
814 -- have this expectation, given the RM permission. Furthermore, other
815 -- Ada compilers do allow such out of range results.
817 -- Note that we do this transformation even if overflow checking is
818 -- off, since this is precisely about giving the "right" result and
819 -- avoiding the need for an overflow check.
821 if Is_Signed_Integer_Type (Typ)
822 and then Nkind (Parent (N)) = N_Type_Conversion
825 Target_Type : constant Entity_Id :=
826 Base_Type (Entity (Subtype_Mark (Parent (N))));
840 if Is_Integer_Type (Target_Type)
841 and then RM_Size (Root_Type (Target_Type)) >= 2 * RM_Size (Rtyp)
843 Tlo := Expr_Value (Type_Low_Bound (Target_Type));
844 Thi := Expr_Value (Type_High_Bound (Target_Type));
847 (Left_Opnd (N), LOK, Llo, Lhi, Assume_Valid => True);
849 (Right_Opnd (N), ROK, Rlo, Rhi, Assume_Valid => True);
852 and then Tlo <= Llo and then Lhi <= Thi
853 and then Tlo <= Rlo and then Rhi <= Thi
855 Determine_Range (N, VOK, Vlo, Vhi, Assume_Valid => True);
857 if VOK and then Tlo <= Vlo and then Vhi <= Thi then
858 Rewrite (Left_Opnd (N),
859 Make_Type_Conversion (Loc,
860 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
861 Expression => Relocate_Node (Left_Opnd (N))));
863 Rewrite (Right_Opnd (N),
864 Make_Type_Conversion (Loc,
865 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
866 Expression => Relocate_Node (Right_Opnd (N))));
868 Set_Etype (N, Target_Type);
870 Rtyp := Root_Type (Typ);
871 Analyze_And_Resolve (Left_Opnd (N), Target_Type);
872 Analyze_And_Resolve (Right_Opnd (N), Target_Type);
874 -- Given that the target type is twice the size of the
875 -- source type, overflow is now impossible, so we can
876 -- safely kill the overflow check and return.
878 Set_Do_Overflow_Check (N, False);
886 -- Now see if an overflow check is required
889 Siz : constant Int := UI_To_Int (Esize (Rtyp));
890 Dsiz : constant Int := Siz * 2;
897 -- Skip check if back end does overflow checks, or the overflow flag
898 -- is not set anyway, or we are not doing code expansion.
900 -- Special case CLI target, where arithmetic overflow checks can be
901 -- performed for integer and long_integer
903 if Backend_Overflow_Checks_On_Target
904 or else not Do_Overflow_Check (N)
905 or else not Expander_Active
907 (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
912 -- Otherwise, generate the full general code for front end overflow
913 -- detection, which works by doing arithmetic in a larger type:
919 -- Typ (Checktyp (x) op Checktyp (y));
921 -- where Typ is the type of the original expression, and Checktyp is
922 -- an integer type of sufficient length to hold the largest possible
925 -- If the size of check type exceeds the size of Long_Long_Integer,
926 -- we use a different approach, expanding to:
928 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
930 -- where xxx is Add, Multiply or Subtract as appropriate
932 -- Find check type if one exists
934 if Dsiz <= Standard_Integer_Size then
935 Ctyp := Standard_Integer;
937 elsif Dsiz <= Standard_Long_Long_Integer_Size then
938 Ctyp := Standard_Long_Long_Integer;
940 -- No check type exists, use runtime call
943 if Nkind (N) = N_Op_Add then
944 Cent := RE_Add_With_Ovflo_Check;
946 elsif Nkind (N) = N_Op_Multiply then
947 Cent := RE_Multiply_With_Ovflo_Check;
950 pragma Assert (Nkind (N) = N_Op_Subtract);
951 Cent := RE_Subtract_With_Ovflo_Check;
956 Make_Function_Call (Loc,
957 Name => New_Reference_To (RTE (Cent), Loc),
958 Parameter_Associations => New_List (
959 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
960 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
962 Analyze_And_Resolve (N, Typ);
966 -- If we fall through, we have the case where we do the arithmetic
967 -- in the next higher type and get the check by conversion. In these
968 -- cases Ctyp is set to the type to be used as the check type.
970 Opnod := Relocate_Node (N);
972 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
975 Set_Etype (Opnd, Ctyp);
976 Set_Analyzed (Opnd, True);
977 Set_Left_Opnd (Opnod, Opnd);
979 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
982 Set_Etype (Opnd, Ctyp);
983 Set_Analyzed (Opnd, True);
984 Set_Right_Opnd (Opnod, Opnd);
986 -- The type of the operation changes to the base type of the check
987 -- type, and we reset the overflow check indication, since clearly no
988 -- overflow is possible now that we are using a double length type.
989 -- We also set the Analyzed flag to avoid a recursive attempt to
992 Set_Etype (Opnod, Base_Type (Ctyp));
993 Set_Do_Overflow_Check (Opnod, False);
994 Set_Analyzed (Opnod, True);
996 -- Now build the outer conversion
998 Opnd := OK_Convert_To (Typ, Opnod);
1000 Set_Etype (Opnd, Typ);
1002 -- In the discrete type case, we directly generate the range check
1003 -- for the outer operand. This range check will implement the
1004 -- required overflow check.
1006 if Is_Discrete_Type (Typ) then
1008 Generate_Range_Check
1009 (Expression (N), Typ, CE_Overflow_Check_Failed);
1011 -- For other types, we enable overflow checking on the conversion,
1012 -- after setting the node as analyzed to prevent recursive attempts
1013 -- to expand the conversion node.
1016 Set_Analyzed (Opnd, True);
1017 Enable_Overflow_Check (Opnd);
1022 when RE_Not_Available =>
1025 end Apply_Arithmetic_Overflow_Check;
1027 ----------------------------
1028 -- Apply_Constraint_Check --
1029 ----------------------------
1031 procedure Apply_Constraint_Check
1034 No_Sliding : Boolean := False)
1036 Desig_Typ : Entity_Id;
1039 if Inside_A_Generic then
1042 elsif Is_Scalar_Type (Typ) then
1043 Apply_Scalar_Range_Check (N, Typ);
1045 elsif Is_Array_Type (Typ) then
1047 -- A useful optimization: an aggregate with only an others clause
1048 -- always has the right bounds.
1050 if Nkind (N) = N_Aggregate
1051 and then No (Expressions (N))
1053 (First (Choices (First (Component_Associations (N)))))
1059 if Is_Constrained (Typ) then
1060 Apply_Length_Check (N, Typ);
1063 Apply_Range_Check (N, Typ);
1066 Apply_Range_Check (N, Typ);
1069 elsif (Is_Record_Type (Typ)
1070 or else Is_Private_Type (Typ))
1071 and then Has_Discriminants (Base_Type (Typ))
1072 and then Is_Constrained (Typ)
1074 Apply_Discriminant_Check (N, Typ);
1076 elsif Is_Access_Type (Typ) then
1078 Desig_Typ := Designated_Type (Typ);
1080 -- No checks necessary if expression statically null
1082 if Known_Null (N) then
1083 if Can_Never_Be_Null (Typ) then
1084 Install_Null_Excluding_Check (N);
1087 -- No sliding possible on access to arrays
1089 elsif Is_Array_Type (Desig_Typ) then
1090 if Is_Constrained (Desig_Typ) then
1091 Apply_Length_Check (N, Typ);
1094 Apply_Range_Check (N, Typ);
1096 elsif Has_Discriminants (Base_Type (Desig_Typ))
1097 and then Is_Constrained (Desig_Typ)
1099 Apply_Discriminant_Check (N, Typ);
1102 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1103 -- this check if the constraint node is illegal, as shown by having
1104 -- an error posted. This additional guard prevents cascaded errors
1105 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1107 if Can_Never_Be_Null (Typ)
1108 and then not Can_Never_Be_Null (Etype (N))
1109 and then not Error_Posted (N)
1111 Install_Null_Excluding_Check (N);
1114 end Apply_Constraint_Check;
1116 ------------------------------
1117 -- Apply_Discriminant_Check --
1118 ------------------------------
1120 procedure Apply_Discriminant_Check
1123 Lhs : Node_Id := Empty)
1125 Loc : constant Source_Ptr := Sloc (N);
1126 Do_Access : constant Boolean := Is_Access_Type (Typ);
1127 S_Typ : Entity_Id := Etype (N);
1131 function Is_Aliased_Unconstrained_Component return Boolean;
1132 -- It is possible for an aliased component to have a nominal
1133 -- unconstrained subtype (through instantiation). If this is a
1134 -- discriminated component assigned in the expansion of an aggregate
1135 -- in an initialization, the check must be suppressed. This unusual
1136 -- situation requires a predicate of its own.
1138 ----------------------------------------
1139 -- Is_Aliased_Unconstrained_Component --
1140 ----------------------------------------
1142 function Is_Aliased_Unconstrained_Component return Boolean is
1147 if Nkind (Lhs) /= N_Selected_Component then
1150 Comp := Entity (Selector_Name (Lhs));
1151 Pref := Prefix (Lhs);
1154 if Ekind (Comp) /= E_Component
1155 or else not Is_Aliased (Comp)
1160 return not Comes_From_Source (Pref)
1161 and then In_Instance
1162 and then not Is_Constrained (Etype (Comp));
1163 end Is_Aliased_Unconstrained_Component;
1165 -- Start of processing for Apply_Discriminant_Check
1169 T_Typ := Designated_Type (Typ);
1174 -- Nothing to do if discriminant checks are suppressed or else no code
1175 -- is to be generated
1177 if not Expander_Active
1178 or else Discriminant_Checks_Suppressed (T_Typ)
1183 -- No discriminant checks necessary for an access when expression is
1184 -- statically Null. This is not only an optimization, it is fundamental
1185 -- because otherwise discriminant checks may be generated in init procs
1186 -- for types containing an access to a not-yet-frozen record, causing a
1187 -- deadly forward reference.
1189 -- Also, if the expression is of an access type whose designated type is
1190 -- incomplete, then the access value must be null and we suppress the
1193 if Known_Null (N) then
1196 elsif Is_Access_Type (S_Typ) then
1197 S_Typ := Designated_Type (S_Typ);
1199 if Ekind (S_Typ) = E_Incomplete_Type then
1204 -- If an assignment target is present, then we need to generate the
1205 -- actual subtype if the target is a parameter or aliased object with
1206 -- an unconstrained nominal subtype.
1208 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1209 -- subtype to the parameter and dereference cases, since other aliased
1210 -- objects are unconstrained (unless the nominal subtype is explicitly
1211 -- constrained). (But we also need to test for renamings???)
1214 and then (Present (Param_Entity (Lhs))
1215 or else (Ada_Version < Ada_05
1216 and then not Is_Constrained (T_Typ)
1217 and then Is_Aliased_View (Lhs)
1218 and then not Is_Aliased_Unconstrained_Component)
1219 or else (Ada_Version >= Ada_05
1220 and then not Is_Constrained (T_Typ)
1221 and then Nkind (Lhs) = N_Explicit_Dereference
1222 and then Nkind (Original_Node (Lhs)) /=
1225 T_Typ := Get_Actual_Subtype (Lhs);
1228 -- Nothing to do if the type is unconstrained (this is the case where
1229 -- the actual subtype in the RM sense of N is unconstrained and no check
1232 if not Is_Constrained (T_Typ) then
1235 -- Ada 2005: nothing to do if the type is one for which there is a
1236 -- partial view that is constrained.
1238 elsif Ada_Version >= Ada_05
1239 and then Has_Constrained_Partial_View (Base_Type (T_Typ))
1244 -- Nothing to do if the type is an Unchecked_Union
1246 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1250 -- Suppress checks if the subtypes are the same. the check must be
1251 -- preserved in an assignment to a formal, because the constraint is
1252 -- given by the actual.
1254 if Nkind (Original_Node (N)) /= N_Allocator
1256 or else not Is_Entity_Name (Lhs)
1257 or else No (Param_Entity (Lhs)))
1260 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1261 and then not Is_Aliased_View (Lhs)
1266 -- We can also eliminate checks on allocators with a subtype mark that
1267 -- coincides with the context type. The context type may be a subtype
1268 -- without a constraint (common case, a generic actual).
1270 elsif Nkind (Original_Node (N)) = N_Allocator
1271 and then Is_Entity_Name (Expression (Original_Node (N)))
1274 Alloc_Typ : constant Entity_Id :=
1275 Entity (Expression (Original_Node (N)));
1278 if Alloc_Typ = T_Typ
1279 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1280 and then Is_Entity_Name (
1281 Subtype_Indication (Parent (T_Typ)))
1282 and then Alloc_Typ = Base_Type (T_Typ))
1290 -- See if we have a case where the types are both constrained, and all
1291 -- the constraints are constants. In this case, we can do the check
1292 -- successfully at compile time.
1294 -- We skip this check for the case where the node is a rewritten`
1295 -- allocator, because it already carries the context subtype, and
1296 -- extracting the discriminants from the aggregate is messy.
1298 if Is_Constrained (S_Typ)
1299 and then Nkind (Original_Node (N)) /= N_Allocator
1309 -- S_Typ may not have discriminants in the case where it is a
1310 -- private type completed by a default discriminated type. In that
1311 -- case, we need to get the constraints from the underlying_type.
1312 -- If the underlying type is unconstrained (i.e. has no default
1313 -- discriminants) no check is needed.
1315 if Has_Discriminants (S_Typ) then
1316 Discr := First_Discriminant (S_Typ);
1317 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1320 Discr := First_Discriminant (Underlying_Type (S_Typ));
1323 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1329 -- A further optimization: if T_Typ is derived from S_Typ
1330 -- without imposing a constraint, no check is needed.
1332 if Nkind (Original_Node (Parent (T_Typ))) =
1333 N_Full_Type_Declaration
1336 Type_Def : constant Node_Id :=
1338 (Original_Node (Parent (T_Typ)));
1340 if Nkind (Type_Def) = N_Derived_Type_Definition
1341 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1342 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1350 DconT := First_Elmt (Discriminant_Constraint (T_Typ));
1352 while Present (Discr) loop
1353 ItemS := Node (DconS);
1354 ItemT := Node (DconT);
1356 -- For a discriminated component type constrained by the
1357 -- current instance of an enclosing type, there is no
1358 -- applicable discriminant check.
1360 if Nkind (ItemT) = N_Attribute_Reference
1361 and then Is_Access_Type (Etype (ItemT))
1362 and then Is_Entity_Name (Prefix (ItemT))
1363 and then Is_Type (Entity (Prefix (ItemT)))
1368 -- If the expressions for the discriminants are identical
1369 -- and it is side-effect free (for now just an entity),
1370 -- this may be a shared constraint, e.g. from a subtype
1371 -- without a constraint introduced as a generic actual.
1372 -- Examine other discriminants if any.
1375 and then Is_Entity_Name (ItemS)
1379 elsif not Is_OK_Static_Expression (ItemS)
1380 or else not Is_OK_Static_Expression (ItemT)
1384 elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
1385 if Do_Access then -- needs run-time check.
1388 Apply_Compile_Time_Constraint_Error
1389 (N, "incorrect value for discriminant&?",
1390 CE_Discriminant_Check_Failed, Ent => Discr);
1397 Next_Discriminant (Discr);
1406 -- Here we need a discriminant check. First build the expression
1407 -- for the comparisons of the discriminants:
1409 -- (n.disc1 /= typ.disc1) or else
1410 -- (n.disc2 /= typ.disc2) or else
1412 -- (n.discn /= typ.discn)
1414 Cond := Build_Discriminant_Checks (N, T_Typ);
1416 -- If Lhs is set and is a parameter, then the condition is
1417 -- guarded by: lhs'constrained and then (condition built above)
1419 if Present (Param_Entity (Lhs)) then
1423 Make_Attribute_Reference (Loc,
1424 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1425 Attribute_Name => Name_Constrained),
1426 Right_Opnd => Cond);
1430 Cond := Guard_Access (Cond, Loc, N);
1434 Make_Raise_Constraint_Error (Loc,
1436 Reason => CE_Discriminant_Check_Failed));
1437 end Apply_Discriminant_Check;
1439 ------------------------
1440 -- Apply_Divide_Check --
1441 ------------------------
1443 procedure Apply_Divide_Check (N : Node_Id) is
1444 Loc : constant Source_Ptr := Sloc (N);
1445 Typ : constant Entity_Id := Etype (N);
1446 Left : constant Node_Id := Left_Opnd (N);
1447 Right : constant Node_Id := Right_Opnd (N);
1457 pragma Warnings (Off, Lhi);
1458 -- Don't actually use this value
1462 and then not Backend_Divide_Checks_On_Target
1463 and then Check_Needed (Right, Division_Check)
1465 Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True);
1467 -- See if division by zero possible, and if so generate test. This
1468 -- part of the test is not controlled by the -gnato switch.
1470 if Do_Division_Check (N) then
1471 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1473 Make_Raise_Constraint_Error (Loc,
1476 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1477 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1478 Reason => CE_Divide_By_Zero));
1482 -- Test for extremely annoying case of xxx'First divided by -1
1484 if Do_Overflow_Check (N) then
1485 if Nkind (N) = N_Op_Divide
1486 and then Is_Signed_Integer_Type (Typ)
1488 Determine_Range (Left, LOK, Llo, Lhi, Assume_Valid => True);
1489 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1491 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1493 ((not LOK) or else (Llo = LLB))
1496 Make_Raise_Constraint_Error (Loc,
1502 Duplicate_Subexpr_Move_Checks (Left),
1503 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1507 Duplicate_Subexpr (Right),
1509 Make_Integer_Literal (Loc, -1))),
1510 Reason => CE_Overflow_Check_Failed));
1515 end Apply_Divide_Check;
1517 ----------------------------------
1518 -- Apply_Float_Conversion_Check --
1519 ----------------------------------
1521 -- Let F and I be the source and target types of the conversion. The RM
1522 -- specifies that a floating-point value X is rounded to the nearest
1523 -- integer, with halfway cases being rounded away from zero. The rounded
1524 -- value of X is checked against I'Range.
1526 -- The catch in the above paragraph is that there is no good way to know
1527 -- whether the round-to-integer operation resulted in overflow. A remedy is
1528 -- to perform a range check in the floating-point domain instead, however:
1530 -- (1) The bounds may not be known at compile time
1531 -- (2) The check must take into account rounding or truncation.
1532 -- (3) The range of type I may not be exactly representable in F.
1533 -- (4) For the rounding case, The end-points I'First - 0.5 and
1534 -- I'Last + 0.5 may or may not be in range, depending on the
1535 -- sign of I'First and I'Last.
1536 -- (5) X may be a NaN, which will fail any comparison
1538 -- The following steps correctly convert X with rounding:
1540 -- (1) If either I'First or I'Last is not known at compile time, use
1541 -- I'Base instead of I in the next three steps and perform a
1542 -- regular range check against I'Range after conversion.
1543 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1544 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1545 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1546 -- In other words, take one of the closest floating-point numbers
1547 -- (which is an integer value) to I'First, and see if it is in
1549 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1550 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1551 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1552 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1553 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1555 -- For the truncating case, replace steps (2) and (3) as follows:
1556 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1557 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1559 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1560 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1563 procedure Apply_Float_Conversion_Check
1565 Target_Typ : Entity_Id)
1567 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1568 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1569 Loc : constant Source_Ptr := Sloc (Ck_Node);
1570 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1571 Target_Base : constant Entity_Id :=
1572 Implementation_Base_Type (Target_Typ);
1574 Par : constant Node_Id := Parent (Ck_Node);
1575 pragma Assert (Nkind (Par) = N_Type_Conversion);
1576 -- Parent of check node, must be a type conversion
1578 Truncate : constant Boolean := Float_Truncate (Par);
1579 Max_Bound : constant Uint :=
1581 (Machine_Radix (Expr_Type),
1582 Machine_Mantissa (Expr_Type) - 1) - 1;
1584 -- Largest bound, so bound plus or minus half is a machine number of F
1586 Ifirst, Ilast : Uint;
1587 -- Bounds of integer type
1590 -- Bounds to check in floating-point domain
1592 Lo_OK, Hi_OK : Boolean;
1593 -- True iff Lo resp. Hi belongs to I'Range
1595 Lo_Chk, Hi_Chk : Node_Id;
1596 -- Expressions that are False iff check fails
1598 Reason : RT_Exception_Code;
1601 if not Compile_Time_Known_Value (LB)
1602 or not Compile_Time_Known_Value (HB)
1605 -- First check that the value falls in the range of the base type,
1606 -- to prevent overflow during conversion and then perform a
1607 -- regular range check against the (dynamic) bounds.
1609 pragma Assert (Target_Base /= Target_Typ);
1611 Temp : constant Entity_Id :=
1612 Make_Defining_Identifier (Loc,
1613 Chars => New_Internal_Name ('T'));
1616 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1617 Set_Etype (Temp, Target_Base);
1619 Insert_Action (Parent (Par),
1620 Make_Object_Declaration (Loc,
1621 Defining_Identifier => Temp,
1622 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1623 Expression => New_Copy_Tree (Par)),
1624 Suppress => All_Checks);
1627 Make_Raise_Constraint_Error (Loc,
1630 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1631 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1632 Reason => CE_Range_Check_Failed));
1633 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
1639 -- Get the (static) bounds of the target type
1641 Ifirst := Expr_Value (LB);
1642 Ilast := Expr_Value (HB);
1644 -- A simple optimization: if the expression is a universal literal,
1645 -- we can do the comparison with the bounds and the conversion to
1646 -- an integer type statically. The range checks are unchanged.
1648 if Nkind (Ck_Node) = N_Real_Literal
1649 and then Etype (Ck_Node) = Universal_Real
1650 and then Is_Integer_Type (Target_Typ)
1651 and then Nkind (Parent (Ck_Node)) = N_Type_Conversion
1654 Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node));
1657 if Int_Val <= Ilast and then Int_Val >= Ifirst then
1659 -- Conversion is safe
1661 Rewrite (Parent (Ck_Node),
1662 Make_Integer_Literal (Loc, UI_To_Int (Int_Val)));
1663 Analyze_And_Resolve (Parent (Ck_Node), Target_Typ);
1669 -- Check against lower bound
1671 if Truncate and then Ifirst > 0 then
1672 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
1676 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
1679 elsif abs (Ifirst) < Max_Bound then
1680 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
1681 Lo_OK := (Ifirst > 0);
1684 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
1685 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
1690 -- Lo_Chk := (X >= Lo)
1692 Lo_Chk := Make_Op_Ge (Loc,
1693 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1694 Right_Opnd => Make_Real_Literal (Loc, Lo));
1697 -- Lo_Chk := (X > Lo)
1699 Lo_Chk := Make_Op_Gt (Loc,
1700 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1701 Right_Opnd => Make_Real_Literal (Loc, Lo));
1704 -- Check against higher bound
1706 if Truncate and then Ilast < 0 then
1707 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
1711 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
1714 elsif abs (Ilast) < Max_Bound then
1715 Hi := UR_From_Uint (Ilast) + Ureal_Half;
1716 Hi_OK := (Ilast < 0);
1718 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
1719 Hi_OK := (Hi <= UR_From_Uint (Ilast));
1724 -- Hi_Chk := (X <= Hi)
1726 Hi_Chk := Make_Op_Le (Loc,
1727 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1728 Right_Opnd => Make_Real_Literal (Loc, Hi));
1731 -- Hi_Chk := (X < Hi)
1733 Hi_Chk := Make_Op_Lt (Loc,
1734 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1735 Right_Opnd => Make_Real_Literal (Loc, Hi));
1738 -- If the bounds of the target type are the same as those of the base
1739 -- type, the check is an overflow check as a range check is not
1740 -- performed in these cases.
1742 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
1743 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
1745 Reason := CE_Overflow_Check_Failed;
1747 Reason := CE_Range_Check_Failed;
1750 -- Raise CE if either conditions does not hold
1752 Insert_Action (Ck_Node,
1753 Make_Raise_Constraint_Error (Loc,
1754 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
1756 end Apply_Float_Conversion_Check;
1758 ------------------------
1759 -- Apply_Length_Check --
1760 ------------------------
1762 procedure Apply_Length_Check
1764 Target_Typ : Entity_Id;
1765 Source_Typ : Entity_Id := Empty)
1768 Apply_Selected_Length_Checks
1769 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1770 end Apply_Length_Check;
1772 -----------------------
1773 -- Apply_Range_Check --
1774 -----------------------
1776 procedure Apply_Range_Check
1778 Target_Typ : Entity_Id;
1779 Source_Typ : Entity_Id := Empty)
1782 Apply_Selected_Range_Checks
1783 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1784 end Apply_Range_Check;
1786 ------------------------------
1787 -- Apply_Scalar_Range_Check --
1788 ------------------------------
1790 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
1791 -- off if it is already set on.
1793 procedure Apply_Scalar_Range_Check
1795 Target_Typ : Entity_Id;
1796 Source_Typ : Entity_Id := Empty;
1797 Fixed_Int : Boolean := False)
1799 Parnt : constant Node_Id := Parent (Expr);
1801 Arr : Node_Id := Empty; -- initialize to prevent warning
1802 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
1805 Is_Subscr_Ref : Boolean;
1806 -- Set true if Expr is a subscript
1808 Is_Unconstrained_Subscr_Ref : Boolean;
1809 -- Set true if Expr is a subscript of an unconstrained array. In this
1810 -- case we do not attempt to do an analysis of the value against the
1811 -- range of the subscript, since we don't know the actual subtype.
1814 -- Set to True if Expr should be regarded as a real value even though
1815 -- the type of Expr might be discrete.
1817 procedure Bad_Value;
1818 -- Procedure called if value is determined to be out of range
1824 procedure Bad_Value is
1826 Apply_Compile_Time_Constraint_Error
1827 (Expr, "value not in range of}?", CE_Range_Check_Failed,
1832 -- Start of processing for Apply_Scalar_Range_Check
1835 -- Return if check obviously not needed
1838 -- Not needed inside generic
1842 -- Not needed if previous error
1844 or else Target_Typ = Any_Type
1845 or else Nkind (Expr) = N_Error
1847 -- Not needed for non-scalar type
1849 or else not Is_Scalar_Type (Target_Typ)
1851 -- Not needed if we know node raises CE already
1853 or else Raises_Constraint_Error (Expr)
1858 -- Now, see if checks are suppressed
1861 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
1863 if Is_Subscr_Ref then
1864 Arr := Prefix (Parnt);
1865 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
1868 if not Do_Range_Check (Expr) then
1870 -- Subscript reference. Check for Index_Checks suppressed
1872 if Is_Subscr_Ref then
1874 -- Check array type and its base type
1876 if Index_Checks_Suppressed (Arr_Typ)
1877 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
1881 -- Check array itself if it is an entity name
1883 elsif Is_Entity_Name (Arr)
1884 and then Index_Checks_Suppressed (Entity (Arr))
1888 -- Check expression itself if it is an entity name
1890 elsif Is_Entity_Name (Expr)
1891 and then Index_Checks_Suppressed (Entity (Expr))
1896 -- All other cases, check for Range_Checks suppressed
1899 -- Check target type and its base type
1901 if Range_Checks_Suppressed (Target_Typ)
1902 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
1906 -- Check expression itself if it is an entity name
1908 elsif Is_Entity_Name (Expr)
1909 and then Range_Checks_Suppressed (Entity (Expr))
1913 -- If Expr is part of an assignment statement, then check left
1914 -- side of assignment if it is an entity name.
1916 elsif Nkind (Parnt) = N_Assignment_Statement
1917 and then Is_Entity_Name (Name (Parnt))
1918 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
1925 -- Do not set range checks if they are killed
1927 if Nkind (Expr) = N_Unchecked_Type_Conversion
1928 and then Kill_Range_Check (Expr)
1933 -- Do not set range checks for any values from System.Scalar_Values
1934 -- since the whole idea of such values is to avoid checking them!
1936 if Is_Entity_Name (Expr)
1937 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
1942 -- Now see if we need a check
1944 if No (Source_Typ) then
1945 S_Typ := Etype (Expr);
1947 S_Typ := Source_Typ;
1950 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
1954 Is_Unconstrained_Subscr_Ref :=
1955 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
1957 -- Always do a range check if the source type includes infinities and
1958 -- the target type does not include infinities. We do not do this if
1959 -- range checks are killed.
1961 if Is_Floating_Point_Type (S_Typ)
1962 and then Has_Infinities (S_Typ)
1963 and then not Has_Infinities (Target_Typ)
1965 Enable_Range_Check (Expr);
1968 -- Return if we know expression is definitely in the range of the target
1969 -- type as determined by Determine_Range. Right now we only do this for
1970 -- discrete types, and not fixed-point or floating-point types.
1972 -- The additional less-precise tests below catch these cases
1974 -- Note: skip this if we are given a source_typ, since the point of
1975 -- supplying a Source_Typ is to stop us looking at the expression.
1976 -- We could sharpen this test to be out parameters only ???
1978 if Is_Discrete_Type (Target_Typ)
1979 and then Is_Discrete_Type (Etype (Expr))
1980 and then not Is_Unconstrained_Subscr_Ref
1981 and then No (Source_Typ)
1984 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
1985 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
1990 if Compile_Time_Known_Value (Tlo)
1991 and then Compile_Time_Known_Value (Thi)
1994 Lov : constant Uint := Expr_Value (Tlo);
1995 Hiv : constant Uint := Expr_Value (Thi);
1998 -- If range is null, we for sure have a constraint error
1999 -- (we don't even need to look at the value involved,
2000 -- since all possible values will raise CE).
2007 -- Otherwise determine range of value
2009 Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True);
2013 -- If definitely in range, all OK
2015 if Lo >= Lov and then Hi <= Hiv then
2018 -- If definitely not in range, warn
2020 elsif Lov > Hi or else Hiv < Lo then
2024 -- Otherwise we don't know
2036 Is_Floating_Point_Type (S_Typ)
2037 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
2039 -- Check if we can determine at compile time whether Expr is in the
2040 -- range of the target type. Note that if S_Typ is within the bounds
2041 -- of Target_Typ then this must be the case. This check is meaningful
2042 -- only if this is not a conversion between integer and real types.
2044 if not Is_Unconstrained_Subscr_Ref
2046 Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
2048 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
2050 Is_In_Range (Expr, Target_Typ,
2051 Assume_Valid => True,
2052 Fixed_Int => Fixed_Int,
2053 Int_Real => Int_Real))
2057 elsif Is_Out_Of_Range (Expr, Target_Typ,
2058 Assume_Valid => True,
2059 Fixed_Int => Fixed_Int,
2060 Int_Real => Int_Real)
2065 -- In the floating-point case, we only do range checks if the type is
2066 -- constrained. We definitely do NOT want range checks for unconstrained
2067 -- types, since we want to have infinities
2069 elsif Is_Floating_Point_Type (S_Typ) then
2070 if Is_Constrained (S_Typ) then
2071 Enable_Range_Check (Expr);
2074 -- For all other cases we enable a range check unconditionally
2077 Enable_Range_Check (Expr);
2080 end Apply_Scalar_Range_Check;
2082 ----------------------------------
2083 -- Apply_Selected_Length_Checks --
2084 ----------------------------------
2086 procedure Apply_Selected_Length_Checks
2088 Target_Typ : Entity_Id;
2089 Source_Typ : Entity_Id;
2090 Do_Static : Boolean)
2093 R_Result : Check_Result;
2096 Loc : constant Source_Ptr := Sloc (Ck_Node);
2097 Checks_On : constant Boolean :=
2098 (not Index_Checks_Suppressed (Target_Typ))
2100 (not Length_Checks_Suppressed (Target_Typ));
2103 if not Expander_Active then
2108 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2110 for J in 1 .. 2 loop
2111 R_Cno := R_Result (J);
2112 exit when No (R_Cno);
2114 -- A length check may mention an Itype which is attached to a
2115 -- subsequent node. At the top level in a package this can cause
2116 -- an order-of-elaboration problem, so we make sure that the itype
2117 -- is referenced now.
2119 if Ekind (Current_Scope) = E_Package
2120 and then Is_Compilation_Unit (Current_Scope)
2122 Ensure_Defined (Target_Typ, Ck_Node);
2124 if Present (Source_Typ) then
2125 Ensure_Defined (Source_Typ, Ck_Node);
2127 elsif Is_Itype (Etype (Ck_Node)) then
2128 Ensure_Defined (Etype (Ck_Node), Ck_Node);
2132 -- If the item is a conditional raise of constraint error, then have
2133 -- a look at what check is being performed and ???
2135 if Nkind (R_Cno) = N_Raise_Constraint_Error
2136 and then Present (Condition (R_Cno))
2138 Cond := Condition (R_Cno);
2140 -- Case where node does not now have a dynamic check
2142 if not Has_Dynamic_Length_Check (Ck_Node) then
2144 -- If checks are on, just insert the check
2147 Insert_Action (Ck_Node, R_Cno);
2149 if not Do_Static then
2150 Set_Has_Dynamic_Length_Check (Ck_Node);
2153 -- If checks are off, then analyze the length check after
2154 -- temporarily attaching it to the tree in case the relevant
2155 -- condition can be evaluted at compile time. We still want a
2156 -- compile time warning in this case.
2159 Set_Parent (R_Cno, Ck_Node);
2164 -- Output a warning if the condition is known to be True
2166 if Is_Entity_Name (Cond)
2167 and then Entity (Cond) = Standard_True
2169 Apply_Compile_Time_Constraint_Error
2170 (Ck_Node, "wrong length for array of}?",
2171 CE_Length_Check_Failed,
2175 -- If we were only doing a static check, or if checks are not
2176 -- on, then we want to delete the check, since it is not needed.
2177 -- We do this by replacing the if statement by a null statement
2179 elsif Do_Static or else not Checks_On then
2180 Remove_Warning_Messages (R_Cno);
2181 Rewrite (R_Cno, Make_Null_Statement (Loc));
2185 Install_Static_Check (R_Cno, Loc);
2188 end Apply_Selected_Length_Checks;
2190 ---------------------------------
2191 -- Apply_Selected_Range_Checks --
2192 ---------------------------------
2194 procedure Apply_Selected_Range_Checks
2196 Target_Typ : Entity_Id;
2197 Source_Typ : Entity_Id;
2198 Do_Static : Boolean)
2201 R_Result : Check_Result;
2204 Loc : constant Source_Ptr := Sloc (Ck_Node);
2205 Checks_On : constant Boolean :=
2206 (not Index_Checks_Suppressed (Target_Typ))
2208 (not Range_Checks_Suppressed (Target_Typ));
2211 if not Expander_Active or else not Checks_On then
2216 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2218 for J in 1 .. 2 loop
2220 R_Cno := R_Result (J);
2221 exit when No (R_Cno);
2223 -- If the item is a conditional raise of constraint error, then have
2224 -- a look at what check is being performed and ???
2226 if Nkind (R_Cno) = N_Raise_Constraint_Error
2227 and then Present (Condition (R_Cno))
2229 Cond := Condition (R_Cno);
2231 if not Has_Dynamic_Range_Check (Ck_Node) then
2232 Insert_Action (Ck_Node, R_Cno);
2234 if not Do_Static then
2235 Set_Has_Dynamic_Range_Check (Ck_Node);
2239 -- Output a warning if the condition is known to be True
2241 if Is_Entity_Name (Cond)
2242 and then Entity (Cond) = Standard_True
2244 -- Since an N_Range is technically not an expression, we have
2245 -- to set one of the bounds to C_E and then just flag the
2246 -- N_Range. The warning message will point to the lower bound
2247 -- and complain about a range, which seems OK.
2249 if Nkind (Ck_Node) = N_Range then
2250 Apply_Compile_Time_Constraint_Error
2251 (Low_Bound (Ck_Node), "static range out of bounds of}?",
2252 CE_Range_Check_Failed,
2256 Set_Raises_Constraint_Error (Ck_Node);
2259 Apply_Compile_Time_Constraint_Error
2260 (Ck_Node, "static value out of range of}?",
2261 CE_Range_Check_Failed,
2266 -- If we were only doing a static check, or if checks are not
2267 -- on, then we want to delete the check, since it is not needed.
2268 -- We do this by replacing the if statement by a null statement
2270 elsif Do_Static or else not Checks_On then
2271 Remove_Warning_Messages (R_Cno);
2272 Rewrite (R_Cno, Make_Null_Statement (Loc));
2276 Install_Static_Check (R_Cno, Loc);
2279 end Apply_Selected_Range_Checks;
2281 -------------------------------
2282 -- Apply_Static_Length_Check --
2283 -------------------------------
2285 procedure Apply_Static_Length_Check
2287 Target_Typ : Entity_Id;
2288 Source_Typ : Entity_Id := Empty)
2291 Apply_Selected_Length_Checks
2292 (Expr, Target_Typ, Source_Typ, Do_Static => True);
2293 end Apply_Static_Length_Check;
2295 -------------------------------------
2296 -- Apply_Subscript_Validity_Checks --
2297 -------------------------------------
2299 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
2303 pragma Assert (Nkind (Expr) = N_Indexed_Component);
2305 -- Loop through subscripts
2307 Sub := First (Expressions (Expr));
2308 while Present (Sub) loop
2310 -- Check one subscript. Note that we do not worry about enumeration
2311 -- type with holes, since we will convert the value to a Pos value
2312 -- for the subscript, and that convert will do the necessary validity
2315 Ensure_Valid (Sub, Holes_OK => True);
2317 -- Move to next subscript
2321 end Apply_Subscript_Validity_Checks;
2323 ----------------------------------
2324 -- Apply_Type_Conversion_Checks --
2325 ----------------------------------
2327 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
2328 Target_Type : constant Entity_Id := Etype (N);
2329 Target_Base : constant Entity_Id := Base_Type (Target_Type);
2330 Expr : constant Node_Id := Expression (N);
2331 Expr_Type : constant Entity_Id := Etype (Expr);
2334 if Inside_A_Generic then
2337 -- Skip these checks if serious errors detected, there are some nasty
2338 -- situations of incomplete trees that blow things up.
2340 elsif Serious_Errors_Detected > 0 then
2343 -- Scalar type conversions of the form Target_Type (Expr) require a
2344 -- range check if we cannot be sure that Expr is in the base type of
2345 -- Target_Typ and also that Expr is in the range of Target_Typ. These
2346 -- are not quite the same condition from an implementation point of
2347 -- view, but clearly the second includes the first.
2349 elsif Is_Scalar_Type (Target_Type) then
2351 Conv_OK : constant Boolean := Conversion_OK (N);
2352 -- If the Conversion_OK flag on the type conversion is set and no
2353 -- floating point type is involved in the type conversion then
2354 -- fixed point values must be read as integral values.
2356 Float_To_Int : constant Boolean :=
2357 Is_Floating_Point_Type (Expr_Type)
2358 and then Is_Integer_Type (Target_Type);
2361 if not Overflow_Checks_Suppressed (Target_Base)
2363 In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK)
2364 and then not Float_To_Int
2366 Activate_Overflow_Check (N);
2369 if not Range_Checks_Suppressed (Target_Type)
2370 and then not Range_Checks_Suppressed (Expr_Type)
2372 if Float_To_Int then
2373 Apply_Float_Conversion_Check (Expr, Target_Type);
2375 Apply_Scalar_Range_Check
2376 (Expr, Target_Type, Fixed_Int => Conv_OK);
2381 elsif Comes_From_Source (N)
2382 and then not Discriminant_Checks_Suppressed (Target_Type)
2383 and then Is_Record_Type (Target_Type)
2384 and then Is_Derived_Type (Target_Type)
2385 and then not Is_Tagged_Type (Target_Type)
2386 and then not Is_Constrained (Target_Type)
2387 and then Present (Stored_Constraint (Target_Type))
2389 -- An unconstrained derived type may have inherited discriminant
2390 -- Build an actual discriminant constraint list using the stored
2391 -- constraint, to verify that the expression of the parent type
2392 -- satisfies the constraints imposed by the (unconstrained!)
2393 -- derived type. This applies to value conversions, not to view
2394 -- conversions of tagged types.
2397 Loc : constant Source_Ptr := Sloc (N);
2399 Constraint : Elmt_Id;
2400 Discr_Value : Node_Id;
2403 New_Constraints : constant Elist_Id := New_Elmt_List;
2404 Old_Constraints : constant Elist_Id :=
2405 Discriminant_Constraint (Expr_Type);
2408 Constraint := First_Elmt (Stored_Constraint (Target_Type));
2409 while Present (Constraint) loop
2410 Discr_Value := Node (Constraint);
2412 if Is_Entity_Name (Discr_Value)
2413 and then Ekind (Entity (Discr_Value)) = E_Discriminant
2415 Discr := Corresponding_Discriminant (Entity (Discr_Value));
2418 and then Scope (Discr) = Base_Type (Expr_Type)
2420 -- Parent is constrained by new discriminant. Obtain
2421 -- Value of original discriminant in expression. If the
2422 -- new discriminant has been used to constrain more than
2423 -- one of the stored discriminants, this will provide the
2424 -- required consistency check.
2427 Make_Selected_Component (Loc,
2429 Duplicate_Subexpr_No_Checks
2430 (Expr, Name_Req => True),
2432 Make_Identifier (Loc, Chars (Discr))),
2436 -- Discriminant of more remote ancestor ???
2441 -- Derived type definition has an explicit value for this
2442 -- stored discriminant.
2446 (Duplicate_Subexpr_No_Checks (Discr_Value),
2450 Next_Elmt (Constraint);
2453 -- Use the unconstrained expression type to retrieve the
2454 -- discriminants of the parent, and apply momentarily the
2455 -- discriminant constraint synthesized above.
2457 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
2458 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
2459 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
2462 Make_Raise_Constraint_Error (Loc,
2464 Reason => CE_Discriminant_Check_Failed));
2467 -- For arrays, conversions are applied during expansion, to take into
2468 -- accounts changes of representation. The checks become range checks on
2469 -- the base type or length checks on the subtype, depending on whether
2470 -- the target type is unconstrained or constrained.
2475 end Apply_Type_Conversion_Checks;
2477 ----------------------------------------------
2478 -- Apply_Universal_Integer_Attribute_Checks --
2479 ----------------------------------------------
2481 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
2482 Loc : constant Source_Ptr := Sloc (N);
2483 Typ : constant Entity_Id := Etype (N);
2486 if Inside_A_Generic then
2489 -- Nothing to do if checks are suppressed
2491 elsif Range_Checks_Suppressed (Typ)
2492 and then Overflow_Checks_Suppressed (Typ)
2496 -- Nothing to do if the attribute does not come from source. The
2497 -- internal attributes we generate of this type do not need checks,
2498 -- and furthermore the attempt to check them causes some circular
2499 -- elaboration orders when dealing with packed types.
2501 elsif not Comes_From_Source (N) then
2504 -- If the prefix is a selected component that depends on a discriminant
2505 -- the check may improperly expose a discriminant instead of using
2506 -- the bounds of the object itself. Set the type of the attribute to
2507 -- the base type of the context, so that a check will be imposed when
2508 -- needed (e.g. if the node appears as an index).
2510 elsif Nkind (Prefix (N)) = N_Selected_Component
2511 and then Ekind (Typ) = E_Signed_Integer_Subtype
2512 and then Depends_On_Discriminant (Scalar_Range (Typ))
2514 Set_Etype (N, Base_Type (Typ));
2516 -- Otherwise, replace the attribute node with a type conversion node
2517 -- whose expression is the attribute, retyped to universal integer, and
2518 -- whose subtype mark is the target type. The call to analyze this
2519 -- conversion will set range and overflow checks as required for proper
2520 -- detection of an out of range value.
2523 Set_Etype (N, Universal_Integer);
2524 Set_Analyzed (N, True);
2527 Make_Type_Conversion (Loc,
2528 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
2529 Expression => Relocate_Node (N)));
2531 Analyze_And_Resolve (N, Typ);
2534 end Apply_Universal_Integer_Attribute_Checks;
2536 -------------------------------
2537 -- Build_Discriminant_Checks --
2538 -------------------------------
2540 function Build_Discriminant_Checks
2542 T_Typ : Entity_Id) return Node_Id
2544 Loc : constant Source_Ptr := Sloc (N);
2547 Disc_Ent : Entity_Id;
2551 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
2553 ----------------------------------
2554 -- Aggregate_Discriminant_Value --
2555 ----------------------------------
2557 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
2561 -- The aggregate has been normalized with named associations. We use
2562 -- the Chars field to locate the discriminant to take into account
2563 -- discriminants in derived types, which carry the same name as those
2566 Assoc := First (Component_Associations (N));
2567 while Present (Assoc) loop
2568 if Chars (First (Choices (Assoc))) = Chars (Disc) then
2569 return Expression (Assoc);
2575 -- Discriminant must have been found in the loop above
2577 raise Program_Error;
2578 end Aggregate_Discriminant_Val;
2580 -- Start of processing for Build_Discriminant_Checks
2583 -- Loop through discriminants evolving the condition
2586 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
2588 -- For a fully private type, use the discriminants of the parent type
2590 if Is_Private_Type (T_Typ)
2591 and then No (Full_View (T_Typ))
2593 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
2595 Disc_Ent := First_Discriminant (T_Typ);
2598 while Present (Disc) loop
2599 Dval := Node (Disc);
2601 if Nkind (Dval) = N_Identifier
2602 and then Ekind (Entity (Dval)) = E_Discriminant
2604 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
2606 Dval := Duplicate_Subexpr_No_Checks (Dval);
2609 -- If we have an Unchecked_Union node, we can infer the discriminants
2612 if Is_Unchecked_Union (Base_Type (T_Typ)) then
2614 Get_Discriminant_Value (
2615 First_Discriminant (T_Typ),
2617 Stored_Constraint (T_Typ)));
2619 elsif Nkind (N) = N_Aggregate then
2621 Duplicate_Subexpr_No_Checks
2622 (Aggregate_Discriminant_Val (Disc_Ent));
2626 Make_Selected_Component (Loc,
2628 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
2630 Make_Identifier (Loc, Chars (Disc_Ent)));
2632 Set_Is_In_Discriminant_Check (Dref);
2635 Evolve_Or_Else (Cond,
2638 Right_Opnd => Dval));
2641 Next_Discriminant (Disc_Ent);
2645 end Build_Discriminant_Checks;
2651 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
2659 -- Always check if not simple entity
2661 if Nkind (Nod) not in N_Has_Entity
2662 or else not Comes_From_Source (Nod)
2667 -- Look up tree for short circuit
2674 -- Done if out of subexpression (note that we allow generated stuff
2675 -- such as itype declarations in this context, to keep the loop going
2676 -- since we may well have generated such stuff in complex situations.
2677 -- Also done if no parent (probably an error condition, but no point
2678 -- in behaving nasty if we find it!)
2681 or else (K not in N_Subexpr and then Comes_From_Source (P))
2685 -- Or/Or Else case, where test is part of the right operand, or is
2686 -- part of one of the actions associated with the right operand, and
2687 -- the left operand is an equality test.
2689 elsif K = N_Op_Or then
2690 exit when N = Right_Opnd (P)
2691 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2693 elsif K = N_Or_Else then
2694 exit when (N = Right_Opnd (P)
2697 and then List_Containing (N) = Actions (P)))
2698 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2700 -- Similar test for the And/And then case, where the left operand
2701 -- is an inequality test.
2703 elsif K = N_Op_And then
2704 exit when N = Right_Opnd (P)
2705 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2707 elsif K = N_And_Then then
2708 exit when (N = Right_Opnd (P)
2711 and then List_Containing (N) = Actions (P)))
2712 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2718 -- If we fall through the loop, then we have a conditional with an
2719 -- appropriate test as its left operand. So test further.
2722 R := Right_Opnd (L);
2725 -- Left operand of test must match original variable
2727 if Nkind (L) not in N_Has_Entity
2728 or else Entity (L) /= Entity (Nod)
2733 -- Right operand of test must be key value (zero or null)
2736 when Access_Check =>
2737 if not Known_Null (R) then
2741 when Division_Check =>
2742 if not Compile_Time_Known_Value (R)
2743 or else Expr_Value (R) /= Uint_0
2749 raise Program_Error;
2752 -- Here we have the optimizable case, warn if not short-circuited
2754 if K = N_Op_And or else K = N_Op_Or then
2756 when Access_Check =>
2758 ("Constraint_Error may be raised (access check)?",
2760 when Division_Check =>
2762 ("Constraint_Error may be raised (zero divide)?",
2766 raise Program_Error;
2769 if K = N_Op_And then
2770 Error_Msg_N ("use `AND THEN` instead of AND?", P);
2772 Error_Msg_N ("use `OR ELSE` instead of OR?", P);
2775 -- If not short-circuited, we need the ckeck
2779 -- If short-circuited, we can omit the check
2786 -----------------------------------
2787 -- Check_Valid_Lvalue_Subscripts --
2788 -----------------------------------
2790 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
2792 -- Skip this if range checks are suppressed
2794 if Range_Checks_Suppressed (Etype (Expr)) then
2797 -- Only do this check for expressions that come from source. We assume
2798 -- that expander generated assignments explicitly include any necessary
2799 -- checks. Note that this is not just an optimization, it avoids
2800 -- infinite recursions!
2802 elsif not Comes_From_Source (Expr) then
2805 -- For a selected component, check the prefix
2807 elsif Nkind (Expr) = N_Selected_Component then
2808 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2811 -- Case of indexed component
2813 elsif Nkind (Expr) = N_Indexed_Component then
2814 Apply_Subscript_Validity_Checks (Expr);
2816 -- Prefix may itself be or contain an indexed component, and these
2817 -- subscripts need checking as well.
2819 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2821 end Check_Valid_Lvalue_Subscripts;
2823 ----------------------------------
2824 -- Null_Exclusion_Static_Checks --
2825 ----------------------------------
2827 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
2828 Error_Node : Node_Id;
2830 Has_Null : constant Boolean := Has_Null_Exclusion (N);
2831 K : constant Node_Kind := Nkind (N);
2836 (K = N_Component_Declaration
2837 or else K = N_Discriminant_Specification
2838 or else K = N_Function_Specification
2839 or else K = N_Object_Declaration
2840 or else K = N_Parameter_Specification);
2842 if K = N_Function_Specification then
2843 Typ := Etype (Defining_Entity (N));
2845 Typ := Etype (Defining_Identifier (N));
2849 when N_Component_Declaration =>
2850 if Present (Access_Definition (Component_Definition (N))) then
2851 Error_Node := Component_Definition (N);
2853 Error_Node := Subtype_Indication (Component_Definition (N));
2856 when N_Discriminant_Specification =>
2857 Error_Node := Discriminant_Type (N);
2859 when N_Function_Specification =>
2860 Error_Node := Result_Definition (N);
2862 when N_Object_Declaration =>
2863 Error_Node := Object_Definition (N);
2865 when N_Parameter_Specification =>
2866 Error_Node := Parameter_Type (N);
2869 raise Program_Error;
2874 -- Enforce legality rule 3.10 (13): A null exclusion can only be
2875 -- applied to an access [sub]type.
2877 if not Is_Access_Type (Typ) then
2879 ("`NOT NULL` allowed only for an access type", Error_Node);
2881 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
2882 -- be applied to a [sub]type that does not exclude null already.
2884 elsif Can_Never_Be_Null (Typ)
2885 and then Comes_From_Source (Typ)
2888 ("`NOT NULL` not allowed (& already excludes null)",
2893 -- Check that null-excluding objects are always initialized, except for
2894 -- deferred constants, for which the expression will appear in the full
2897 if K = N_Object_Declaration
2898 and then No (Expression (N))
2899 and then not Constant_Present (N)
2900 and then not No_Initialization (N)
2902 -- Add an expression that assigns null. This node is needed by
2903 -- Apply_Compile_Time_Constraint_Error, which will replace this with
2904 -- a Constraint_Error node.
2906 Set_Expression (N, Make_Null (Sloc (N)));
2907 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
2909 Apply_Compile_Time_Constraint_Error
2910 (N => Expression (N),
2911 Msg => "(Ada 2005) null-excluding objects must be initialized?",
2912 Reason => CE_Null_Not_Allowed);
2915 -- Check that a null-excluding component, formal or object is not being
2916 -- assigned a null value. Otherwise generate a warning message and
2917 -- replace Expression (N) by an N_Constraint_Error node.
2919 if K /= N_Function_Specification then
2920 Expr := Expression (N);
2922 if Present (Expr) and then Known_Null (Expr) then
2924 when N_Component_Declaration |
2925 N_Discriminant_Specification =>
2926 Apply_Compile_Time_Constraint_Error
2928 Msg => "(Ada 2005) null not allowed " &
2929 "in null-excluding components?",
2930 Reason => CE_Null_Not_Allowed);
2932 when N_Object_Declaration =>
2933 Apply_Compile_Time_Constraint_Error
2935 Msg => "(Ada 2005) null not allowed " &
2936 "in null-excluding objects?",
2937 Reason => CE_Null_Not_Allowed);
2939 when N_Parameter_Specification =>
2940 Apply_Compile_Time_Constraint_Error
2942 Msg => "(Ada 2005) null not allowed " &
2943 "in null-excluding formals?",
2944 Reason => CE_Null_Not_Allowed);
2951 end Null_Exclusion_Static_Checks;
2953 ----------------------------------
2954 -- Conditional_Statements_Begin --
2955 ----------------------------------
2957 procedure Conditional_Statements_Begin is
2959 Saved_Checks_TOS := Saved_Checks_TOS + 1;
2961 -- If stack overflows, kill all checks, that way we know to simply reset
2962 -- the number of saved checks to zero on return. This should never occur
2965 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2968 -- In the normal case, we just make a new stack entry saving the current
2969 -- number of saved checks for a later restore.
2972 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
2974 if Debug_Flag_CC then
2975 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
2979 end Conditional_Statements_Begin;
2981 --------------------------------
2982 -- Conditional_Statements_End --
2983 --------------------------------
2985 procedure Conditional_Statements_End is
2987 pragma Assert (Saved_Checks_TOS > 0);
2989 -- If the saved checks stack overflowed, then we killed all checks, so
2990 -- setting the number of saved checks back to zero is correct. This
2991 -- should never occur in practice.
2993 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2994 Num_Saved_Checks := 0;
2996 -- In the normal case, restore the number of saved checks from the top
3000 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
3001 if Debug_Flag_CC then
3002 w ("Conditional_Statements_End: Num_Saved_Checks = ",
3007 Saved_Checks_TOS := Saved_Checks_TOS - 1;
3008 end Conditional_Statements_End;
3010 ---------------------
3011 -- Determine_Range --
3012 ---------------------
3014 Cache_Size : constant := 2 ** 10;
3015 type Cache_Index is range 0 .. Cache_Size - 1;
3016 -- Determine size of below cache (power of 2 is more efficient!)
3018 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
3019 Determine_Range_Cache_V : array (Cache_Index) of Boolean;
3020 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
3021 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
3022 -- The above arrays are used to implement a small direct cache for
3023 -- Determine_Range calls. Because of the way Determine_Range recursively
3024 -- traces subexpressions, and because overflow checking calls the routine
3025 -- on the way up the tree, a quadratic behavior can otherwise be
3026 -- encountered in large expressions. The cache entry for node N is stored
3027 -- in the (N mod Cache_Size) entry, and can be validated by checking the
3028 -- actual node value stored there. The Range_Cache_V array records the
3029 -- setting of Assume_Valid for the cache entry.
3031 procedure Determine_Range
3036 Assume_Valid : Boolean := False)
3038 Typ : Entity_Id := Etype (N);
3039 -- Type to use, may get reset to base type for possibly invalid entity
3043 -- Lo and Hi bounds of left operand
3047 -- Lo and Hi bounds of right (or only) operand
3050 -- Temp variable used to hold a bound node
3053 -- High bound of base type of expression
3057 -- Refined values for low and high bounds, after tightening
3060 -- Used in lower level calls to indicate if call succeeded
3062 Cindex : Cache_Index;
3063 -- Used to search cache
3065 function OK_Operands return Boolean;
3066 -- Used for binary operators. Determines the ranges of the left and
3067 -- right operands, and if they are both OK, returns True, and puts
3068 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left
3074 function OK_Operands return Boolean is
3077 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
3084 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3088 -- Start of processing for Determine_Range
3091 -- Prevent junk warnings by initializing range variables
3098 -- If type is not defined, we can't determine its range
3102 -- We don't deal with anything except discrete types
3104 or else not Is_Discrete_Type (Typ)
3106 -- Ignore type for which an error has been posted, since range in
3107 -- this case may well be a bogosity deriving from the error. Also
3108 -- ignore if error posted on the reference node.
3110 or else Error_Posted (N) or else Error_Posted (Typ)
3112 -- Ignore generic type, since range is indeed bogus
3114 or else Is_Generic_Type (Typ)
3120 -- For all other cases, we can determine the range
3124 -- If value is compile time known, then the possible range is the one
3125 -- value that we know this expression definitely has!
3127 if Compile_Time_Known_Value (N) then
3128 Lo := Expr_Value (N);
3133 -- Return if already in the cache
3135 Cindex := Cache_Index (N mod Cache_Size);
3137 if Determine_Range_Cache_N (Cindex) = N
3139 Determine_Range_Cache_V (Cindex) = Assume_Valid
3141 Lo := Determine_Range_Cache_Lo (Cindex);
3142 Hi := Determine_Range_Cache_Hi (Cindex);
3146 -- Otherwise, start by finding the bounds of the type of the expression,
3147 -- the value cannot be outside this range (if it is, then we have an
3148 -- overflow situation, which is a separate check, we are talking here
3149 -- only about the expression value).
3151 -- First step, change to use base type unless we know the value is valid
3153 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
3154 or else Assume_No_Invalid_Values
3155 or else Assume_Valid
3159 Typ := Underlying_Type (Base_Type (Typ));
3162 -- We use the actual bound unless it is dynamic, in which case use the
3163 -- corresponding base type bound if possible. If we can't get a bound
3164 -- then we figure we can't determine the range (a peculiar case, that
3165 -- perhaps cannot happen, but there is no point in bombing in this
3166 -- optimization circuit.
3168 -- First the low bound
3170 Bound := Type_Low_Bound (Typ);
3172 if Compile_Time_Known_Value (Bound) then
3173 Lo := Expr_Value (Bound);
3175 elsif Compile_Time_Known_Value (Type_Low_Bound (Base_Type (Typ))) then
3176 Lo := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
3183 -- Now the high bound
3185 Bound := Type_High_Bound (Typ);
3187 -- We need the high bound of the base type later on, and this should
3188 -- always be compile time known. Again, it is not clear that this
3189 -- can ever be false, but no point in bombing.
3191 if Compile_Time_Known_Value (Type_High_Bound (Base_Type (Typ))) then
3192 Hbound := Expr_Value (Type_High_Bound (Base_Type (Typ)));
3200 -- If we have a static subtype, then that may have a tighter bound so
3201 -- use the upper bound of the subtype instead in this case.
3203 if Compile_Time_Known_Value (Bound) then
3204 Hi := Expr_Value (Bound);
3207 -- We may be able to refine this value in certain situations. If any
3208 -- refinement is possible, then Lor and Hir are set to possibly tighter
3209 -- bounds, and OK1 is set to True.
3213 -- For unary plus, result is limited by range of operand
3217 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
3219 -- For unary minus, determine range of operand, and negate it
3223 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3230 -- For binary addition, get range of each operand and do the
3231 -- addition to get the result range.
3235 Lor := Lo_Left + Lo_Right;
3236 Hir := Hi_Left + Hi_Right;
3239 -- Division is tricky. The only case we consider is where the right
3240 -- operand is a positive constant, and in this case we simply divide
3241 -- the bounds of the left operand
3245 if Lo_Right = Hi_Right
3246 and then Lo_Right > 0
3248 Lor := Lo_Left / Lo_Right;
3249 Hir := Hi_Left / Lo_Right;
3256 -- For binary subtraction, get range of each operand and do the worst
3257 -- case subtraction to get the result range.
3259 when N_Op_Subtract =>
3261 Lor := Lo_Left - Hi_Right;
3262 Hir := Hi_Left - Lo_Right;
3265 -- For MOD, if right operand is a positive constant, then result must
3266 -- be in the allowable range of mod results.
3270 if Lo_Right = Hi_Right
3271 and then Lo_Right /= 0
3273 if Lo_Right > 0 then
3275 Hir := Lo_Right - 1;
3277 else -- Lo_Right < 0
3278 Lor := Lo_Right + 1;
3287 -- For REM, if right operand is a positive constant, then result must
3288 -- be in the allowable range of mod results.
3292 if Lo_Right = Hi_Right
3293 and then Lo_Right /= 0
3296 Dval : constant Uint := (abs Lo_Right) - 1;
3299 -- The sign of the result depends on the sign of the
3300 -- dividend (but not on the sign of the divisor, hence
3301 -- the abs operation above).
3321 -- Attribute reference cases
3323 when N_Attribute_Reference =>
3324 case Attribute_Name (N) is
3326 -- For Pos/Val attributes, we can refine the range using the
3327 -- possible range of values of the attribute expression
3329 when Name_Pos | Name_Val =>
3331 (First (Expressions (N)), OK1, Lor, Hir, Assume_Valid);
3333 -- For Length attribute, use the bounds of the corresponding
3334 -- index type to refine the range.
3338 Atyp : Entity_Id := Etype (Prefix (N));
3346 if Is_Access_Type (Atyp) then
3347 Atyp := Designated_Type (Atyp);
3350 -- For string literal, we know exact value
3352 if Ekind (Atyp) = E_String_Literal_Subtype then
3354 Lo := String_Literal_Length (Atyp);
3355 Hi := String_Literal_Length (Atyp);
3359 -- Otherwise check for expression given
3361 if No (Expressions (N)) then
3365 UI_To_Int (Expr_Value (First (Expressions (N))));
3368 Indx := First_Index (Atyp);
3369 for J in 2 .. Inum loop
3370 Indx := Next_Index (Indx);
3374 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU,
3379 (Type_High_Bound (Etype (Indx)), OK1, UL, UU,
3384 -- The maximum value for Length is the biggest
3385 -- possible gap between the values of the bounds.
3386 -- But of course, this value cannot be negative.
3388 Hir := UI_Max (Uint_0, UU - LL + 1);
3390 -- For constrained arrays, the minimum value for
3391 -- Length is taken from the actual value of the
3392 -- bounds, since the index will be exactly of
3395 if Is_Constrained (Atyp) then
3396 Lor := UI_Max (Uint_0, UL - LU + 1);
3398 -- For an unconstrained array, the minimum value
3399 -- for length is always zero.
3408 -- No special handling for other attributes
3409 -- Probably more opportunities exist here ???
3416 -- For type conversion from one discrete type to another, we can
3417 -- refine the range using the converted value.
3419 when N_Type_Conversion =>
3420 Determine_Range (Expression (N), OK1, Lor, Hir, Assume_Valid);
3422 -- Nothing special to do for all other expression kinds
3430 -- At this stage, if OK1 is true, then we know that the actual
3431 -- result of the computed expression is in the range Lor .. Hir.
3432 -- We can use this to restrict the possible range of results.
3436 -- If the refined value of the low bound is greater than the
3437 -- type high bound, then reset it to the more restrictive
3438 -- value. However, we do NOT do this for the case of a modular
3439 -- type where the possible upper bound on the value is above the
3440 -- base type high bound, because that means the result could wrap.
3443 and then not (Is_Modular_Integer_Type (Typ)
3444 and then Hir > Hbound)
3449 -- Similarly, if the refined value of the high bound is less
3450 -- than the value so far, then reset it to the more restrictive
3451 -- value. Again, we do not do this if the refined low bound is
3452 -- negative for a modular type, since this would wrap.
3455 and then not (Is_Modular_Integer_Type (Typ)
3456 and then Lor < Uint_0)
3462 -- Set cache entry for future call and we are all done
3464 Determine_Range_Cache_N (Cindex) := N;
3465 Determine_Range_Cache_V (Cindex) := Assume_Valid;
3466 Determine_Range_Cache_Lo (Cindex) := Lo;
3467 Determine_Range_Cache_Hi (Cindex) := Hi;
3470 -- If any exception occurs, it means that we have some bug in the compiler
3471 -- possibly triggered by a previous error, or by some unforseen peculiar
3472 -- occurrence. However, this is only an optimization attempt, so there is
3473 -- really no point in crashing the compiler. Instead we just decide, too
3474 -- bad, we can't figure out a range in this case after all.
3479 -- Debug flag K disables this behavior (useful for debugging)
3481 if Debug_Flag_K then
3489 end Determine_Range;
3491 ------------------------------------
3492 -- Discriminant_Checks_Suppressed --
3493 ------------------------------------
3495 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
3498 if Is_Unchecked_Union (E) then
3500 elsif Checks_May_Be_Suppressed (E) then
3501 return Is_Check_Suppressed (E, Discriminant_Check);
3505 return Scope_Suppress (Discriminant_Check);
3506 end Discriminant_Checks_Suppressed;
3508 --------------------------------
3509 -- Division_Checks_Suppressed --
3510 --------------------------------
3512 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
3514 if Present (E) and then Checks_May_Be_Suppressed (E) then
3515 return Is_Check_Suppressed (E, Division_Check);
3517 return Scope_Suppress (Division_Check);
3519 end Division_Checks_Suppressed;
3521 -----------------------------------
3522 -- Elaboration_Checks_Suppressed --
3523 -----------------------------------
3525 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
3527 -- The complication in this routine is that if we are in the dynamic
3528 -- model of elaboration, we also check All_Checks, since All_Checks
3529 -- does not set Elaboration_Check explicitly.
3532 if Kill_Elaboration_Checks (E) then
3535 elsif Checks_May_Be_Suppressed (E) then
3536 if Is_Check_Suppressed (E, Elaboration_Check) then
3538 elsif Dynamic_Elaboration_Checks then
3539 return Is_Check_Suppressed (E, All_Checks);
3546 if Scope_Suppress (Elaboration_Check) then
3548 elsif Dynamic_Elaboration_Checks then
3549 return Scope_Suppress (All_Checks);
3553 end Elaboration_Checks_Suppressed;
3555 ---------------------------
3556 -- Enable_Overflow_Check --
3557 ---------------------------
3559 procedure Enable_Overflow_Check (N : Node_Id) is
3560 Typ : constant Entity_Id := Base_Type (Etype (N));
3569 if Debug_Flag_CC then
3570 w ("Enable_Overflow_Check for node ", Int (N));
3571 Write_Str (" Source location = ");
3576 -- No check if overflow checks suppressed for type of node
3578 if Present (Etype (N))
3579 and then Overflow_Checks_Suppressed (Etype (N))
3583 -- Nothing to do for unsigned integer types, which do not overflow
3585 elsif Is_Modular_Integer_Type (Typ) then
3588 -- Nothing to do if the range of the result is known OK. We skip this
3589 -- for conversions, since the caller already did the check, and in any
3590 -- case the condition for deleting the check for a type conversion is
3593 elsif Nkind (N) /= N_Type_Conversion then
3594 Determine_Range (N, OK, Lo, Hi, Assume_Valid => True);
3596 -- Note in the test below that we assume that the range is not OK
3597 -- if a bound of the range is equal to that of the type. That's not
3598 -- quite accurate but we do this for the following reasons:
3600 -- a) The way that Determine_Range works, it will typically report
3601 -- the bounds of the value as being equal to the bounds of the
3602 -- type, because it either can't tell anything more precise, or
3603 -- does not think it is worth the effort to be more precise.
3605 -- b) It is very unusual to have a situation in which this would
3606 -- generate an unnecessary overflow check (an example would be
3607 -- a subtype with a range 0 .. Integer'Last - 1 to which the
3608 -- literal value one is added).
3610 -- c) The alternative is a lot of special casing in this routine
3611 -- which would partially duplicate Determine_Range processing.
3614 and then Lo > Expr_Value (Type_Low_Bound (Typ))
3615 and then Hi < Expr_Value (Type_High_Bound (Typ))
3617 if Debug_Flag_CC then
3618 w ("No overflow check required");
3625 -- If not in optimizing mode, set flag and we are done. We are also done
3626 -- (and just set the flag) if the type is not a discrete type, since it
3627 -- is not worth the effort to eliminate checks for other than discrete
3628 -- types. In addition, we take this same path if we have stored the
3629 -- maximum number of checks possible already (a very unlikely situation,
3630 -- but we do not want to blow up!)
3632 if Optimization_Level = 0
3633 or else not Is_Discrete_Type (Etype (N))
3634 or else Num_Saved_Checks = Saved_Checks'Last
3636 Activate_Overflow_Check (N);
3638 if Debug_Flag_CC then
3639 w ("Optimization off");
3645 -- Otherwise evaluate and check the expression
3650 Target_Type => Empty,
3656 if Debug_Flag_CC then
3657 w ("Called Find_Check");
3661 w (" Check_Num = ", Chk);
3662 w (" Ent = ", Int (Ent));
3663 Write_Str (" Ofs = ");
3668 -- If check is not of form to optimize, then set flag and we are done
3671 Activate_Overflow_Check (N);
3675 -- If check is already performed, then return without setting flag
3678 if Debug_Flag_CC then
3679 w ("Check suppressed!");
3685 -- Here we will make a new entry for the new check
3687 Activate_Overflow_Check (N);
3688 Num_Saved_Checks := Num_Saved_Checks + 1;
3689 Saved_Checks (Num_Saved_Checks) :=
3694 Target_Type => Empty);
3696 if Debug_Flag_CC then
3697 w ("Make new entry, check number = ", Num_Saved_Checks);
3698 w (" Entity = ", Int (Ent));
3699 Write_Str (" Offset = ");
3701 w (" Check_Type = O");
3702 w (" Target_Type = Empty");
3705 -- If we get an exception, then something went wrong, probably because of
3706 -- an error in the structure of the tree due to an incorrect program. Or it
3707 -- may be a bug in the optimization circuit. In either case the safest
3708 -- thing is simply to set the check flag unconditionally.
3712 Activate_Overflow_Check (N);
3714 if Debug_Flag_CC then
3715 w (" exception occurred, overflow flag set");
3719 end Enable_Overflow_Check;
3721 ------------------------
3722 -- Enable_Range_Check --
3723 ------------------------
3725 procedure Enable_Range_Check (N : Node_Id) is
3734 -- Return if unchecked type conversion with range check killed. In this
3735 -- case we never set the flag (that's what Kill_Range_Check is about!)
3737 if Nkind (N) = N_Unchecked_Type_Conversion
3738 and then Kill_Range_Check (N)
3743 -- Check for various cases where we should suppress the range check
3745 -- No check if range checks suppressed for type of node
3747 if Present (Etype (N))
3748 and then Range_Checks_Suppressed (Etype (N))
3752 -- No check if node is an entity name, and range checks are suppressed
3753 -- for this entity, or for the type of this entity.
3755 elsif Is_Entity_Name (N)
3756 and then (Range_Checks_Suppressed (Entity (N))
3757 or else Range_Checks_Suppressed (Etype (Entity (N))))
3761 -- No checks if index of array, and index checks are suppressed for
3762 -- the array object or the type of the array.
3764 elsif Nkind (Parent (N)) = N_Indexed_Component then
3766 Pref : constant Node_Id := Prefix (Parent (N));
3768 if Is_Entity_Name (Pref)
3769 and then Index_Checks_Suppressed (Entity (Pref))
3772 elsif Index_Checks_Suppressed (Etype (Pref)) then
3778 -- Debug trace output
3780 if Debug_Flag_CC then
3781 w ("Enable_Range_Check for node ", Int (N));
3782 Write_Str (" Source location = ");
3787 -- If not in optimizing mode, set flag and we are done. We are also done
3788 -- (and just set the flag) if the type is not a discrete type, since it
3789 -- is not worth the effort to eliminate checks for other than discrete
3790 -- types. In addition, we take this same path if we have stored the
3791 -- maximum number of checks possible already (a very unlikely situation,
3792 -- but we do not want to blow up!)
3794 if Optimization_Level = 0
3795 or else No (Etype (N))
3796 or else not Is_Discrete_Type (Etype (N))
3797 or else Num_Saved_Checks = Saved_Checks'Last
3799 Activate_Range_Check (N);
3801 if Debug_Flag_CC then
3802 w ("Optimization off");
3808 -- Otherwise find out the target type
3812 -- For assignment, use left side subtype
3814 if Nkind (P) = N_Assignment_Statement
3815 and then Expression (P) = N
3817 Ttyp := Etype (Name (P));
3819 -- For indexed component, use subscript subtype
3821 elsif Nkind (P) = N_Indexed_Component then
3828 Atyp := Etype (Prefix (P));
3830 if Is_Access_Type (Atyp) then
3831 Atyp := Designated_Type (Atyp);
3833 -- If the prefix is an access to an unconstrained array,
3834 -- perform check unconditionally: it depends on the bounds of
3835 -- an object and we cannot currently recognize whether the test
3836 -- may be redundant.
3838 if not Is_Constrained (Atyp) then
3839 Activate_Range_Check (N);
3843 -- Ditto if the prefix is an explicit dereference whose designated
3844 -- type is unconstrained.
3846 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
3847 and then not Is_Constrained (Atyp)
3849 Activate_Range_Check (N);
3853 Indx := First_Index (Atyp);
3854 Subs := First (Expressions (P));
3857 Ttyp := Etype (Indx);
3866 -- For now, ignore all other cases, they are not so interesting
3869 if Debug_Flag_CC then
3870 w (" target type not found, flag set");
3873 Activate_Range_Check (N);
3877 -- Evaluate and check the expression
3882 Target_Type => Ttyp,
3888 if Debug_Flag_CC then
3889 w ("Called Find_Check");
3890 w ("Target_Typ = ", Int (Ttyp));
3894 w (" Check_Num = ", Chk);
3895 w (" Ent = ", Int (Ent));
3896 Write_Str (" Ofs = ");
3901 -- If check is not of form to optimize, then set flag and we are done
3904 if Debug_Flag_CC then
3905 w (" expression not of optimizable type, flag set");
3908 Activate_Range_Check (N);
3912 -- If check is already performed, then return without setting flag
3915 if Debug_Flag_CC then
3916 w ("Check suppressed!");
3922 -- Here we will make a new entry for the new check
3924 Activate_Range_Check (N);
3925 Num_Saved_Checks := Num_Saved_Checks + 1;
3926 Saved_Checks (Num_Saved_Checks) :=
3931 Target_Type => Ttyp);
3933 if Debug_Flag_CC then
3934 w ("Make new entry, check number = ", Num_Saved_Checks);
3935 w (" Entity = ", Int (Ent));
3936 Write_Str (" Offset = ");
3938 w (" Check_Type = R");
3939 w (" Target_Type = ", Int (Ttyp));
3940 pg (Union_Id (Ttyp));
3943 -- If we get an exception, then something went wrong, probably because of
3944 -- an error in the structure of the tree due to an incorrect program. Or
3945 -- it may be a bug in the optimization circuit. In either case the safest
3946 -- thing is simply to set the check flag unconditionally.
3950 Activate_Range_Check (N);
3952 if Debug_Flag_CC then
3953 w (" exception occurred, range flag set");
3957 end Enable_Range_Check;
3963 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
3964 Typ : constant Entity_Id := Etype (Expr);
3967 -- Ignore call if we are not doing any validity checking
3969 if not Validity_Checks_On then
3972 -- Ignore call if range or validity checks suppressed on entity or type
3974 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
3977 -- No check required if expression is from the expander, we assume the
3978 -- expander will generate whatever checks are needed. Note that this is
3979 -- not just an optimization, it avoids infinite recursions!
3981 -- Unchecked conversions must be checked, unless they are initialized
3982 -- scalar values, as in a component assignment in an init proc.
3984 -- In addition, we force a check if Force_Validity_Checks is set
3986 elsif not Comes_From_Source (Expr)
3987 and then not Force_Validity_Checks
3988 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
3989 or else Kill_Range_Check (Expr))
3993 -- No check required if expression is known to have valid value
3995 elsif Expr_Known_Valid (Expr) then
3998 -- Ignore case of enumeration with holes where the flag is set not to
3999 -- worry about holes, since no special validity check is needed
4001 elsif Is_Enumeration_Type (Typ)
4002 and then Has_Non_Standard_Rep (Typ)
4007 -- No check required on the left-hand side of an assignment
4009 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
4010 and then Expr = Name (Parent (Expr))
4014 -- No check on a univeral real constant. The context will eventually
4015 -- convert it to a machine number for some target type, or report an
4018 elsif Nkind (Expr) = N_Real_Literal
4019 and then Etype (Expr) = Universal_Real
4023 -- If the expression denotes a component of a packed boolean arrray,
4024 -- no possible check applies. We ignore the old ACATS chestnuts that
4025 -- involve Boolean range True..True.
4027 -- Note: validity checks are generated for expressions that yield a
4028 -- scalar type, when it is possible to create a value that is outside of
4029 -- the type. If this is a one-bit boolean no such value exists. This is
4030 -- an optimization, and it also prevents compiler blowing up during the
4031 -- elaboration of improperly expanded packed array references.
4033 elsif Nkind (Expr) = N_Indexed_Component
4034 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
4035 and then Root_Type (Etype (Expr)) = Standard_Boolean
4039 -- An annoying special case. If this is an out parameter of a scalar
4040 -- type, then the value is not going to be accessed, therefore it is
4041 -- inappropriate to do any validity check at the call site.
4044 -- Only need to worry about scalar types
4046 if Is_Scalar_Type (Typ) then
4056 -- Find actual argument (which may be a parameter association)
4057 -- and the parent of the actual argument (the call statement)
4062 if Nkind (P) = N_Parameter_Association then
4067 -- Only need to worry if we are argument of a procedure call
4068 -- since functions don't have out parameters. If this is an
4069 -- indirect or dispatching call, get signature from the
4072 if Nkind (P) = N_Procedure_Call_Statement then
4073 L := Parameter_Associations (P);
4075 if Is_Entity_Name (Name (P)) then
4076 E := Entity (Name (P));
4078 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
4079 E := Etype (Name (P));
4082 -- Only need to worry if there are indeed actuals, and if
4083 -- this could be a procedure call, otherwise we cannot get a
4084 -- match (either we are not an argument, or the mode of the
4085 -- formal is not OUT). This test also filters out the
4088 if Is_Non_Empty_List (L)
4089 and then Is_Subprogram (E)
4091 -- This is the loop through parameters, looking for an
4092 -- OUT parameter for which we are the argument.
4094 F := First_Formal (E);
4096 while Present (F) loop
4097 if Ekind (F) = E_Out_Parameter and then A = N then
4110 -- If we fall through, a validity check is required
4112 Insert_Valid_Check (Expr);
4114 if Is_Entity_Name (Expr)
4115 and then Safe_To_Capture_Value (Expr, Entity (Expr))
4117 Set_Is_Known_Valid (Entity (Expr));
4121 ----------------------
4122 -- Expr_Known_Valid --
4123 ----------------------
4125 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
4126 Typ : constant Entity_Id := Etype (Expr);
4129 -- Non-scalar types are always considered valid, since they never give
4130 -- rise to the issues of erroneous or bounded error behavior that are
4131 -- the concern. In formal reference manual terms the notion of validity
4132 -- only applies to scalar types. Note that even when packed arrays are
4133 -- represented using modular types, they are still arrays semantically,
4134 -- so they are also always valid (in particular, the unused bits can be
4135 -- random rubbish without affecting the validity of the array value).
4137 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
4140 -- If no validity checking, then everything is considered valid
4142 elsif not Validity_Checks_On then
4145 -- Floating-point types are considered valid unless floating-point
4146 -- validity checks have been specifically turned on.
4148 elsif Is_Floating_Point_Type (Typ)
4149 and then not Validity_Check_Floating_Point
4153 -- If the expression is the value of an object that is known to be
4154 -- valid, then clearly the expression value itself is valid.
4156 elsif Is_Entity_Name (Expr)
4157 and then Is_Known_Valid (Entity (Expr))
4161 -- References to discriminants are always considered valid. The value
4162 -- of a discriminant gets checked when the object is built. Within the
4163 -- record, we consider it valid, and it is important to do so, since
4164 -- otherwise we can try to generate bogus validity checks which
4165 -- reference discriminants out of scope. Discriminants of concurrent
4166 -- types are excluded for the same reason.
4168 elsif Is_Entity_Name (Expr)
4169 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
4173 -- If the type is one for which all values are known valid, then we are
4174 -- sure that the value is valid except in the slightly odd case where
4175 -- the expression is a reference to a variable whose size has been
4176 -- explicitly set to a value greater than the object size.
4178 elsif Is_Known_Valid (Typ) then
4179 if Is_Entity_Name (Expr)
4180 and then Ekind (Entity (Expr)) = E_Variable
4181 and then Esize (Entity (Expr)) > Esize (Typ)
4188 -- Integer and character literals always have valid values, where
4189 -- appropriate these will be range checked in any case.
4191 elsif Nkind (Expr) = N_Integer_Literal
4193 Nkind (Expr) = N_Character_Literal
4197 -- If we have a type conversion or a qualification of a known valid
4198 -- value, then the result will always be valid.
4200 elsif Nkind (Expr) = N_Type_Conversion
4202 Nkind (Expr) = N_Qualified_Expression
4204 return Expr_Known_Valid (Expression (Expr));
4206 -- The result of any operator is always considered valid, since we
4207 -- assume the necessary checks are done by the operator. For operators
4208 -- on floating-point operations, we must also check when the operation
4209 -- is the right-hand side of an assignment, or is an actual in a call.
4211 elsif Nkind (Expr) in N_Op then
4212 if Is_Floating_Point_Type (Typ)
4213 and then Validity_Check_Floating_Point
4215 (Nkind (Parent (Expr)) = N_Assignment_Statement
4216 or else Nkind (Parent (Expr)) = N_Function_Call
4217 or else Nkind (Parent (Expr)) = N_Parameter_Association)
4224 -- The result of a membership test is always valid, since it is true or
4225 -- false, there are no other possibilities.
4227 elsif Nkind (Expr) in N_Membership_Test then
4230 -- For all other cases, we do not know the expression is valid
4235 end Expr_Known_Valid;
4241 procedure Find_Check
4243 Check_Type : Character;
4244 Target_Type : Entity_Id;
4245 Entry_OK : out Boolean;
4246 Check_Num : out Nat;
4247 Ent : out Entity_Id;
4250 function Within_Range_Of
4251 (Target_Type : Entity_Id;
4252 Check_Type : Entity_Id) return Boolean;
4253 -- Given a requirement for checking a range against Target_Type, and
4254 -- and a range Check_Type against which a check has already been made,
4255 -- determines if the check against check type is sufficient to ensure
4256 -- that no check against Target_Type is required.
4258 ---------------------
4259 -- Within_Range_Of --
4260 ---------------------
4262 function Within_Range_Of
4263 (Target_Type : Entity_Id;
4264 Check_Type : Entity_Id) return Boolean
4267 if Target_Type = Check_Type then
4272 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
4273 Thi : constant Node_Id := Type_High_Bound (Target_Type);
4274 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
4275 Chi : constant Node_Id := Type_High_Bound (Check_Type);
4279 or else (Compile_Time_Known_Value (Tlo)
4281 Compile_Time_Known_Value (Clo)
4283 Expr_Value (Clo) >= Expr_Value (Tlo)))
4286 or else (Compile_Time_Known_Value (Thi)
4288 Compile_Time_Known_Value (Chi)
4290 Expr_Value (Chi) <= Expr_Value (Clo)))
4298 end Within_Range_Of;
4300 -- Start of processing for Find_Check
4303 -- Establish default, to avoid warnings from GCC
4307 -- Case of expression is simple entity reference
4309 if Is_Entity_Name (Expr) then
4310 Ent := Entity (Expr);
4313 -- Case of expression is entity + known constant
4315 elsif Nkind (Expr) = N_Op_Add
4316 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4317 and then Is_Entity_Name (Left_Opnd (Expr))
4319 Ent := Entity (Left_Opnd (Expr));
4320 Ofs := Expr_Value (Right_Opnd (Expr));
4322 -- Case of expression is entity - known constant
4324 elsif Nkind (Expr) = N_Op_Subtract
4325 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4326 and then Is_Entity_Name (Left_Opnd (Expr))
4328 Ent := Entity (Left_Opnd (Expr));
4329 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
4331 -- Any other expression is not of the right form
4340 -- Come here with expression of appropriate form, check if entity is an
4341 -- appropriate one for our purposes.
4343 if (Ekind (Ent) = E_Variable
4344 or else Is_Constant_Object (Ent))
4345 and then not Is_Library_Level_Entity (Ent)
4353 -- See if there is matching check already
4355 for J in reverse 1 .. Num_Saved_Checks loop
4357 SC : Saved_Check renames Saved_Checks (J);
4360 if SC.Killed = False
4361 and then SC.Entity = Ent
4362 and then SC.Offset = Ofs
4363 and then SC.Check_Type = Check_Type
4364 and then Within_Range_Of (Target_Type, SC.Target_Type)
4372 -- If we fall through entry was not found
4378 ---------------------------------
4379 -- Generate_Discriminant_Check --
4380 ---------------------------------
4382 -- Note: the code for this procedure is derived from the
4383 -- Emit_Discriminant_Check Routine in trans.c.
4385 procedure Generate_Discriminant_Check (N : Node_Id) is
4386 Loc : constant Source_Ptr := Sloc (N);
4387 Pref : constant Node_Id := Prefix (N);
4388 Sel : constant Node_Id := Selector_Name (N);
4390 Orig_Comp : constant Entity_Id :=
4391 Original_Record_Component (Entity (Sel));
4392 -- The original component to be checked
4394 Discr_Fct : constant Entity_Id :=
4395 Discriminant_Checking_Func (Orig_Comp);
4396 -- The discriminant checking function
4399 -- One discriminant to be checked in the type
4401 Real_Discr : Entity_Id;
4402 -- Actual discriminant in the call
4404 Pref_Type : Entity_Id;
4405 -- Type of relevant prefix (ignoring private/access stuff)
4408 -- List of arguments for function call
4411 -- Keep track of the formal corresponding to the actual we build for
4412 -- each discriminant, in order to be able to perform the necessary type
4416 -- Selected component reference for checking function argument
4419 Pref_Type := Etype (Pref);
4421 -- Force evaluation of the prefix, so that it does not get evaluated
4422 -- twice (once for the check, once for the actual reference). Such a
4423 -- double evaluation is always a potential source of inefficiency,
4424 -- and is functionally incorrect in the volatile case, or when the
4425 -- prefix may have side-effects. An entity or a component of an
4426 -- entity requires no evaluation.
4428 if Is_Entity_Name (Pref) then
4429 if Treat_As_Volatile (Entity (Pref)) then
4430 Force_Evaluation (Pref, Name_Req => True);
4433 elsif Treat_As_Volatile (Etype (Pref)) then
4434 Force_Evaluation (Pref, Name_Req => True);
4436 elsif Nkind (Pref) = N_Selected_Component
4437 and then Is_Entity_Name (Prefix (Pref))
4442 Force_Evaluation (Pref, Name_Req => True);
4445 -- For a tagged type, use the scope of the original component to
4446 -- obtain the type, because ???
4448 if Is_Tagged_Type (Scope (Orig_Comp)) then
4449 Pref_Type := Scope (Orig_Comp);
4451 -- For an untagged derived type, use the discriminants of the parent
4452 -- which have been renamed in the derivation, possibly by a one-to-many
4453 -- discriminant constraint. For non-tagged type, initially get the Etype
4457 if Is_Derived_Type (Pref_Type)
4458 and then Number_Discriminants (Pref_Type) /=
4459 Number_Discriminants (Etype (Base_Type (Pref_Type)))
4461 Pref_Type := Etype (Base_Type (Pref_Type));
4465 -- We definitely should have a checking function, This routine should
4466 -- not be called if no discriminant checking function is present.
4468 pragma Assert (Present (Discr_Fct));
4470 -- Create the list of the actual parameters for the call. This list
4471 -- is the list of the discriminant fields of the record expression to
4472 -- be discriminant checked.
4475 Formal := First_Formal (Discr_Fct);
4476 Discr := First_Discriminant (Pref_Type);
4477 while Present (Discr) loop
4479 -- If we have a corresponding discriminant field, and a parent
4480 -- subtype is present, then we want to use the corresponding
4481 -- discriminant since this is the one with the useful value.
4483 if Present (Corresponding_Discriminant (Discr))
4484 and then Ekind (Pref_Type) = E_Record_Type
4485 and then Present (Parent_Subtype (Pref_Type))
4487 Real_Discr := Corresponding_Discriminant (Discr);
4489 Real_Discr := Discr;
4492 -- Construct the reference to the discriminant
4495 Make_Selected_Component (Loc,
4497 Unchecked_Convert_To (Pref_Type,
4498 Duplicate_Subexpr (Pref)),
4499 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
4501 -- Manually analyze and resolve this selected component. We really
4502 -- want it just as it appears above, and do not want the expander
4503 -- playing discriminal games etc with this reference. Then we append
4504 -- the argument to the list we are gathering.
4506 Set_Etype (Scomp, Etype (Real_Discr));
4507 Set_Analyzed (Scomp, True);
4508 Append_To (Args, Convert_To (Etype (Formal), Scomp));
4510 Next_Formal_With_Extras (Formal);
4511 Next_Discriminant (Discr);
4514 -- Now build and insert the call
4517 Make_Raise_Constraint_Error (Loc,
4519 Make_Function_Call (Loc,
4520 Name => New_Occurrence_Of (Discr_Fct, Loc),
4521 Parameter_Associations => Args),
4522 Reason => CE_Discriminant_Check_Failed));
4523 end Generate_Discriminant_Check;
4525 ---------------------------
4526 -- Generate_Index_Checks --
4527 ---------------------------
4529 procedure Generate_Index_Checks (N : Node_Id) is
4530 Loc : constant Source_Ptr := Sloc (N);
4531 A : constant Node_Id := Prefix (N);
4537 -- Ignore call if index checks suppressed for array object or type
4539 if (Is_Entity_Name (A) and then Index_Checks_Suppressed (Entity (A)))
4540 or else Index_Checks_Suppressed (Etype (A))
4545 -- Generate the checks
4547 Sub := First (Expressions (N));
4549 while Present (Sub) loop
4550 if Do_Range_Check (Sub) then
4551 Set_Do_Range_Check (Sub, False);
4553 -- Force evaluation except for the case of a simple name of a
4554 -- non-volatile entity.
4556 if not Is_Entity_Name (Sub)
4557 or else Treat_As_Volatile (Entity (Sub))
4559 Force_Evaluation (Sub);
4562 -- Generate a raise of constraint error with the appropriate
4563 -- reason and a condition of the form:
4565 -- Base_Type(Sub) not in array'range (subscript)
4567 -- Note that the reason we generate the conversion to the base
4568 -- type here is that we definitely want the range check to take
4569 -- place, even if it looks like the subtype is OK. Optimization
4570 -- considerations that allow us to omit the check have already
4571 -- been taken into account in the setting of the Do_Range_Check
4577 Num := New_List (Make_Integer_Literal (Loc, Ind));
4581 Make_Raise_Constraint_Error (Loc,
4585 Convert_To (Base_Type (Etype (Sub)),
4586 Duplicate_Subexpr_Move_Checks (Sub)),
4588 Make_Attribute_Reference (Loc,
4590 Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
4591 Attribute_Name => Name_Range,
4592 Expressions => Num)),
4593 Reason => CE_Index_Check_Failed));
4599 end Generate_Index_Checks;
4601 --------------------------
4602 -- Generate_Range_Check --
4603 --------------------------
4605 procedure Generate_Range_Check
4607 Target_Type : Entity_Id;
4608 Reason : RT_Exception_Code)
4610 Loc : constant Source_Ptr := Sloc (N);
4611 Source_Type : constant Entity_Id := Etype (N);
4612 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
4613 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
4616 -- First special case, if the source type is already within the range
4617 -- of the target type, then no check is needed (probably we should have
4618 -- stopped Do_Range_Check from being set in the first place, but better
4619 -- late than later in preventing junk code!
4621 -- We do NOT apply this if the source node is a literal, since in this
4622 -- case the literal has already been labeled as having the subtype of
4625 if In_Subrange_Of (Source_Type, Target_Type)
4627 (Nkind (N) = N_Integer_Literal
4629 Nkind (N) = N_Real_Literal
4631 Nkind (N) = N_Character_Literal
4634 and then Ekind (Entity (N)) = E_Enumeration_Literal))
4639 -- We need a check, so force evaluation of the node, so that it does
4640 -- not get evaluated twice (once for the check, once for the actual
4641 -- reference). Such a double evaluation is always a potential source
4642 -- of inefficiency, and is functionally incorrect in the volatile case.
4644 if not Is_Entity_Name (N)
4645 or else Treat_As_Volatile (Entity (N))
4647 Force_Evaluation (N);
4650 -- The easiest case is when Source_Base_Type and Target_Base_Type are
4651 -- the same since in this case we can simply do a direct check of the
4652 -- value of N against the bounds of Target_Type.
4654 -- [constraint_error when N not in Target_Type]
4656 -- Note: this is by far the most common case, for example all cases of
4657 -- checks on the RHS of assignments are in this category, but not all
4658 -- cases are like this. Notably conversions can involve two types.
4660 if Source_Base_Type = Target_Base_Type then
4662 Make_Raise_Constraint_Error (Loc,
4665 Left_Opnd => Duplicate_Subexpr (N),
4666 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4669 -- Next test for the case where the target type is within the bounds
4670 -- of the base type of the source type, since in this case we can
4671 -- simply convert these bounds to the base type of T to do the test.
4673 -- [constraint_error when N not in
4674 -- Source_Base_Type (Target_Type'First)
4676 -- Source_Base_Type(Target_Type'Last))]
4678 -- The conversions will always work and need no check
4680 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
4682 Make_Raise_Constraint_Error (Loc,
4685 Left_Opnd => Duplicate_Subexpr (N),
4690 Convert_To (Source_Base_Type,
4691 Make_Attribute_Reference (Loc,
4693 New_Occurrence_Of (Target_Type, Loc),
4694 Attribute_Name => Name_First)),
4697 Convert_To (Source_Base_Type,
4698 Make_Attribute_Reference (Loc,
4700 New_Occurrence_Of (Target_Type, Loc),
4701 Attribute_Name => Name_Last)))),
4704 -- Note that at this stage we now that the Target_Base_Type is not in
4705 -- the range of the Source_Base_Type (since even the Target_Type itself
4706 -- is not in this range). It could still be the case that Source_Type is
4707 -- in range of the target base type since we have not checked that case.
4709 -- If that is the case, we can freely convert the source to the target,
4710 -- and then test the target result against the bounds.
4712 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
4714 -- We make a temporary to hold the value of the converted value
4715 -- (converted to the base type), and then we will do the test against
4718 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
4719 -- [constraint_error when Tnn not in Target_Type]
4721 -- Then the conversion itself is replaced by an occurrence of Tnn
4724 Tnn : constant Entity_Id :=
4725 Make_Defining_Identifier (Loc,
4726 Chars => New_Internal_Name ('T'));
4729 Insert_Actions (N, New_List (
4730 Make_Object_Declaration (Loc,
4731 Defining_Identifier => Tnn,
4732 Object_Definition =>
4733 New_Occurrence_Of (Target_Base_Type, Loc),
4734 Constant_Present => True,
4736 Make_Type_Conversion (Loc,
4737 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
4738 Expression => Duplicate_Subexpr (N))),
4740 Make_Raise_Constraint_Error (Loc,
4743 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4744 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4746 Reason => Reason)));
4748 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4750 -- Set the type of N, because the declaration for Tnn might not
4751 -- be analyzed yet, as is the case if N appears within a record
4752 -- declaration, as a discriminant constraint or expression.
4754 Set_Etype (N, Target_Base_Type);
4757 -- At this stage, we know that we have two scalar types, which are
4758 -- directly convertible, and where neither scalar type has a base
4759 -- range that is in the range of the other scalar type.
4761 -- The only way this can happen is with a signed and unsigned type.
4762 -- So test for these two cases:
4765 -- Case of the source is unsigned and the target is signed
4767 if Is_Unsigned_Type (Source_Base_Type)
4768 and then not Is_Unsigned_Type (Target_Base_Type)
4770 -- If the source is unsigned and the target is signed, then we
4771 -- know that the source is not shorter than the target (otherwise
4772 -- the source base type would be in the target base type range).
4774 -- In other words, the unsigned type is either the same size as
4775 -- the target, or it is larger. It cannot be smaller.
4778 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
4780 -- We only need to check the low bound if the low bound of the
4781 -- target type is non-negative. If the low bound of the target
4782 -- type is negative, then we know that we will fit fine.
4784 -- If the high bound of the target type is negative, then we
4785 -- know we have a constraint error, since we can't possibly
4786 -- have a negative source.
4788 -- With these two checks out of the way, we can do the check
4789 -- using the source type safely
4791 -- This is definitely the most annoying case!
4793 -- [constraint_error
4794 -- when (Target_Type'First >= 0
4796 -- N < Source_Base_Type (Target_Type'First))
4797 -- or else Target_Type'Last < 0
4798 -- or else N > Source_Base_Type (Target_Type'Last)];
4800 -- We turn off all checks since we know that the conversions
4801 -- will work fine, given the guards for negative values.
4804 Make_Raise_Constraint_Error (Loc,
4810 Left_Opnd => Make_Op_Ge (Loc,
4812 Make_Attribute_Reference (Loc,
4814 New_Occurrence_Of (Target_Type, Loc),
4815 Attribute_Name => Name_First),
4816 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4820 Left_Opnd => Duplicate_Subexpr (N),
4822 Convert_To (Source_Base_Type,
4823 Make_Attribute_Reference (Loc,
4825 New_Occurrence_Of (Target_Type, Loc),
4826 Attribute_Name => Name_First)))),
4831 Make_Attribute_Reference (Loc,
4832 Prefix => New_Occurrence_Of (Target_Type, Loc),
4833 Attribute_Name => Name_Last),
4834 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
4838 Left_Opnd => Duplicate_Subexpr (N),
4840 Convert_To (Source_Base_Type,
4841 Make_Attribute_Reference (Loc,
4842 Prefix => New_Occurrence_Of (Target_Type, Loc),
4843 Attribute_Name => Name_Last)))),
4846 Suppress => All_Checks);
4848 -- Only remaining possibility is that the source is signed and
4849 -- the target is unsigned.
4852 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
4853 and then Is_Unsigned_Type (Target_Base_Type));
4855 -- If the source is signed and the target is unsigned, then we
4856 -- know that the target is not shorter than the source (otherwise
4857 -- the target base type would be in the source base type range).
4859 -- In other words, the unsigned type is either the same size as
4860 -- the target, or it is larger. It cannot be smaller.
4862 -- Clearly we have an error if the source value is negative since
4863 -- no unsigned type can have negative values. If the source type
4864 -- is non-negative, then the check can be done using the target
4867 -- Tnn : constant Target_Base_Type (N) := Target_Type;
4869 -- [constraint_error
4870 -- when N < 0 or else Tnn not in Target_Type];
4872 -- We turn off all checks for the conversion of N to the target
4873 -- base type, since we generate the explicit check to ensure that
4874 -- the value is non-negative
4877 Tnn : constant Entity_Id :=
4878 Make_Defining_Identifier (Loc,
4879 Chars => New_Internal_Name ('T'));
4882 Insert_Actions (N, New_List (
4883 Make_Object_Declaration (Loc,
4884 Defining_Identifier => Tnn,
4885 Object_Definition =>
4886 New_Occurrence_Of (Target_Base_Type, Loc),
4887 Constant_Present => True,
4889 Make_Type_Conversion (Loc,
4891 New_Occurrence_Of (Target_Base_Type, Loc),
4892 Expression => Duplicate_Subexpr (N))),
4894 Make_Raise_Constraint_Error (Loc,
4899 Left_Opnd => Duplicate_Subexpr (N),
4900 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4904 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4906 New_Occurrence_Of (Target_Type, Loc))),
4909 Suppress => All_Checks);
4911 -- Set the Etype explicitly, because Insert_Actions may have
4912 -- placed the declaration in the freeze list for an enclosing
4913 -- construct, and thus it is not analyzed yet.
4915 Set_Etype (Tnn, Target_Base_Type);
4916 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4920 end Generate_Range_Check;
4926 function Get_Check_Id (N : Name_Id) return Check_Id is
4928 -- For standard check name, we can do a direct computation
4930 if N in First_Check_Name .. Last_Check_Name then
4931 return Check_Id (N - (First_Check_Name - 1));
4933 -- For non-standard names added by pragma Check_Name, search table
4936 for J in All_Checks + 1 .. Check_Names.Last loop
4937 if Check_Names.Table (J) = N then
4943 -- No matching name found
4948 ---------------------
4949 -- Get_Discriminal --
4950 ---------------------
4952 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
4953 Loc : constant Source_Ptr := Sloc (E);
4958 -- The bound can be a bona fide parameter of a protected operation,
4959 -- rather than a prival encoded as an in-parameter.
4961 if No (Discriminal_Link (Entity (Bound))) then
4965 -- Climb the scope stack looking for an enclosing protected type. If
4966 -- we run out of scopes, return the bound itself.
4969 while Present (Sc) loop
4970 if Sc = Standard_Standard then
4973 elsif Ekind (Sc) = E_Protected_Type then
4980 D := First_Discriminant (Sc);
4981 while Present (D) loop
4982 if Chars (D) = Chars (Bound) then
4983 return New_Occurrence_Of (Discriminal (D), Loc);
4986 Next_Discriminant (D);
4990 end Get_Discriminal;
4992 ----------------------
4993 -- Get_Range_Checks --
4994 ----------------------
4996 function Get_Range_Checks
4998 Target_Typ : Entity_Id;
4999 Source_Typ : Entity_Id := Empty;
5000 Warn_Node : Node_Id := Empty) return Check_Result
5003 return Selected_Range_Checks
5004 (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
5005 end Get_Range_Checks;
5011 function Guard_Access
5014 Ck_Node : Node_Id) return Node_Id
5017 if Nkind (Cond) = N_Or_Else then
5018 Set_Paren_Count (Cond, 1);
5021 if Nkind (Ck_Node) = N_Allocator then
5028 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
5029 Right_Opnd => Make_Null (Loc)),
5030 Right_Opnd => Cond);
5034 -----------------------------
5035 -- Index_Checks_Suppressed --
5036 -----------------------------
5038 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
5040 if Present (E) and then Checks_May_Be_Suppressed (E) then
5041 return Is_Check_Suppressed (E, Index_Check);
5043 return Scope_Suppress (Index_Check);
5045 end Index_Checks_Suppressed;
5051 procedure Initialize is
5053 for J in Determine_Range_Cache_N'Range loop
5054 Determine_Range_Cache_N (J) := Empty;
5059 for J in Int range 1 .. All_Checks loop
5060 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
5064 -------------------------
5065 -- Insert_Range_Checks --
5066 -------------------------
5068 procedure Insert_Range_Checks
5069 (Checks : Check_Result;
5071 Suppress_Typ : Entity_Id;
5072 Static_Sloc : Source_Ptr := No_Location;
5073 Flag_Node : Node_Id := Empty;
5074 Do_Before : Boolean := False)
5076 Internal_Flag_Node : Node_Id := Flag_Node;
5077 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
5079 Check_Node : Node_Id;
5080 Checks_On : constant Boolean :=
5081 (not Index_Checks_Suppressed (Suppress_Typ))
5083 (not Range_Checks_Suppressed (Suppress_Typ));
5086 -- For now we just return if Checks_On is false, however this should be
5087 -- enhanced to check for an always True value in the condition and to
5088 -- generate a compilation warning???
5090 if not Expander_Active or else not Checks_On then
5094 if Static_Sloc = No_Location then
5095 Internal_Static_Sloc := Sloc (Node);
5098 if No (Flag_Node) then
5099 Internal_Flag_Node := Node;
5102 for J in 1 .. 2 loop
5103 exit when No (Checks (J));
5105 if Nkind (Checks (J)) = N_Raise_Constraint_Error
5106 and then Present (Condition (Checks (J)))
5108 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
5109 Check_Node := Checks (J);
5110 Mark_Rewrite_Insertion (Check_Node);
5113 Insert_Before_And_Analyze (Node, Check_Node);
5115 Insert_After_And_Analyze (Node, Check_Node);
5118 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
5123 Make_Raise_Constraint_Error (Internal_Static_Sloc,
5124 Reason => CE_Range_Check_Failed);
5125 Mark_Rewrite_Insertion (Check_Node);
5128 Insert_Before_And_Analyze (Node, Check_Node);
5130 Insert_After_And_Analyze (Node, Check_Node);
5134 end Insert_Range_Checks;
5136 ------------------------
5137 -- Insert_Valid_Check --
5138 ------------------------
5140 procedure Insert_Valid_Check (Expr : Node_Id) is
5141 Loc : constant Source_Ptr := Sloc (Expr);
5145 -- Do not insert if checks off, or if not checking validity or
5146 -- if expression is known to be valid
5148 if not Validity_Checks_On
5149 or else Range_Or_Validity_Checks_Suppressed (Expr)
5150 or else Expr_Known_Valid (Expr)
5155 -- If we have a checked conversion, then validity check applies to
5156 -- the expression inside the conversion, not the result, since if
5157 -- the expression inside is valid, then so is the conversion result.
5160 while Nkind (Exp) = N_Type_Conversion loop
5161 Exp := Expression (Exp);
5164 -- We are about to insert the validity check for Exp. We save and
5165 -- reset the Do_Range_Check flag over this validity check, and then
5166 -- put it back for the final original reference (Exp may be rewritten).
5169 DRC : constant Boolean := Do_Range_Check (Exp);
5172 Set_Do_Range_Check (Exp, False);
5174 -- Force evaluation to avoid multiple reads for atomic/volatile
5176 if Is_Entity_Name (Exp)
5177 and then Is_Volatile (Entity (Exp))
5179 Force_Evaluation (Exp, Name_Req => True);
5182 -- Insert the validity check. Note that we do this with validity
5183 -- checks turned off, to avoid recursion, we do not want validity
5184 -- checks on the validity checking code itself!
5188 Make_Raise_Constraint_Error (Loc,
5192 Make_Attribute_Reference (Loc,
5194 Duplicate_Subexpr_No_Checks (Exp, Name_Req => True),
5195 Attribute_Name => Name_Valid)),
5196 Reason => CE_Invalid_Data),
5197 Suppress => Validity_Check);
5199 -- If the expression is a a reference to an element of a bit-packed
5200 -- array, then it is rewritten as a renaming declaration. If the
5201 -- expression is an actual in a call, it has not been expanded,
5202 -- waiting for the proper point at which to do it. The same happens
5203 -- with renamings, so that we have to force the expansion now. This
5204 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
5207 if Is_Entity_Name (Exp)
5208 and then Nkind (Parent (Entity (Exp))) =
5209 N_Object_Renaming_Declaration
5212 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
5214 if Nkind (Old_Exp) = N_Indexed_Component
5215 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
5217 Expand_Packed_Element_Reference (Old_Exp);
5222 -- Put back the Do_Range_Check flag on the resulting (possibly
5223 -- rewritten) expression.
5225 -- Note: it might be thought that a validity check is not required
5226 -- when a range check is present, but that's not the case, because
5227 -- the back end is allowed to assume for the range check that the
5228 -- operand is within its declared range (an assumption that validity
5229 -- checking is all about NOT assuming!)
5231 -- Note: no need to worry about Possible_Local_Raise here, it will
5232 -- already have been called if original node has Do_Range_Check set.
5234 Set_Do_Range_Check (Exp, DRC);
5236 end Insert_Valid_Check;
5238 ----------------------------------
5239 -- Install_Null_Excluding_Check --
5240 ----------------------------------
5242 procedure Install_Null_Excluding_Check (N : Node_Id) is
5243 Loc : constant Source_Ptr := Sloc (N);
5244 Typ : constant Entity_Id := Etype (N);
5246 function In_Declarative_Region_Of_Subprogram_Body return Boolean;
5247 -- Determine whether node N, a reference to an *in* parameter, is
5248 -- inside the declarative region of the current subprogram body.
5250 procedure Mark_Non_Null;
5251 -- After installation of check, if the node in question is an entity
5252 -- name, then mark this entity as non-null if possible.
5254 ----------------------------------------------
5255 -- In_Declarative_Region_Of_Subprogram_Body --
5256 ----------------------------------------------
5258 function In_Declarative_Region_Of_Subprogram_Body return Boolean is
5259 E : constant Entity_Id := Entity (N);
5260 S : constant Entity_Id := Current_Scope;
5264 pragma Assert (Ekind (E) = E_In_Parameter);
5266 -- Two initial context checks. We must be inside a subprogram body
5267 -- with declarations and reference must not appear in nested scopes.
5269 if (Ekind (S) /= E_Function
5270 and then Ekind (S) /= E_Procedure)
5271 or else Scope (E) /= S
5276 S_Par := Parent (Parent (S));
5278 if Nkind (S_Par) /= N_Subprogram_Body
5279 or else No (Declarations (S_Par))
5289 -- Retrieve the declaration node of N (if any). Note that N
5290 -- may be a part of a complex initialization expression.
5294 while Present (P) loop
5296 -- While traversing the parent chain, we find that N
5297 -- belongs to a statement, thus it may never appear in
5298 -- a declarative region.
5300 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
5301 or else Nkind (P) = N_Procedure_Call_Statement
5306 if Nkind (P) in N_Declaration
5307 and then Nkind (P) not in N_Subprogram_Specification
5320 return List_Containing (N_Decl) = Declarations (S_Par);
5322 end In_Declarative_Region_Of_Subprogram_Body;
5328 procedure Mark_Non_Null is
5330 -- Only case of interest is if node N is an entity name
5332 if Is_Entity_Name (N) then
5334 -- For sure, we want to clear an indication that this is known to
5335 -- be null, since if we get past this check, it definitely is not!
5337 Set_Is_Known_Null (Entity (N), False);
5339 -- We can mark the entity as known to be non-null if either it is
5340 -- safe to capture the value, or in the case of an IN parameter,
5341 -- which is a constant, if the check we just installed is in the
5342 -- declarative region of the subprogram body. In this latter case,
5343 -- a check is decisive for the rest of the body, since we know we
5344 -- must complete all declarations before executing the body.
5346 if Safe_To_Capture_Value (N, Entity (N))
5348 (Ekind (Entity (N)) = E_In_Parameter
5349 and then In_Declarative_Region_Of_Subprogram_Body)
5351 Set_Is_Known_Non_Null (Entity (N));
5356 -- Start of processing for Install_Null_Excluding_Check
5359 pragma Assert (Is_Access_Type (Typ));
5361 -- No check inside a generic (why not???)
5363 if Inside_A_Generic then
5367 -- No check needed if known to be non-null
5369 if Known_Non_Null (N) then
5373 -- If known to be null, here is where we generate a compile time check
5375 if Known_Null (N) then
5377 -- Avoid generating warning message inside init procs
5379 if not Inside_Init_Proc then
5380 Apply_Compile_Time_Constraint_Error
5382 "null value not allowed here?",
5383 CE_Access_Check_Failed);
5386 Make_Raise_Constraint_Error (Loc,
5387 Reason => CE_Access_Check_Failed));
5394 -- If entity is never assigned, for sure a warning is appropriate
5396 if Is_Entity_Name (N) then
5397 Check_Unset_Reference (N);
5400 -- No check needed if checks are suppressed on the range. Note that we
5401 -- don't set Is_Known_Non_Null in this case (we could legitimately do
5402 -- so, since the program is erroneous, but we don't like to casually
5403 -- propagate such conclusions from erroneosity).
5405 if Access_Checks_Suppressed (Typ) then
5409 -- No check needed for access to concurrent record types generated by
5410 -- the expander. This is not just an optimization (though it does indeed
5411 -- remove junk checks). It also avoids generation of junk warnings.
5413 if Nkind (N) in N_Has_Chars
5414 and then Chars (N) = Name_uObject
5415 and then Is_Concurrent_Record_Type
5416 (Directly_Designated_Type (Etype (N)))
5421 -- Otherwise install access check
5424 Make_Raise_Constraint_Error (Loc,
5427 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
5428 Right_Opnd => Make_Null (Loc)),
5429 Reason => CE_Access_Check_Failed));
5432 end Install_Null_Excluding_Check;
5434 --------------------------
5435 -- Install_Static_Check --
5436 --------------------------
5438 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
5439 Stat : constant Boolean := Is_Static_Expression (R_Cno);
5440 Typ : constant Entity_Id := Etype (R_Cno);
5444 Make_Raise_Constraint_Error (Loc,
5445 Reason => CE_Range_Check_Failed));
5446 Set_Analyzed (R_Cno);
5447 Set_Etype (R_Cno, Typ);
5448 Set_Raises_Constraint_Error (R_Cno);
5449 Set_Is_Static_Expression (R_Cno, Stat);
5450 end Install_Static_Check;
5452 ---------------------
5453 -- Kill_All_Checks --
5454 ---------------------
5456 procedure Kill_All_Checks is
5458 if Debug_Flag_CC then
5459 w ("Kill_All_Checks");
5462 -- We reset the number of saved checks to zero, and also modify all
5463 -- stack entries for statement ranges to indicate that the number of
5464 -- checks at each level is now zero.
5466 Num_Saved_Checks := 0;
5468 -- Note: the Int'Min here avoids any possibility of J being out of
5469 -- range when called from e.g. Conditional_Statements_Begin.
5471 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
5472 Saved_Checks_Stack (J) := 0;
5474 end Kill_All_Checks;
5480 procedure Kill_Checks (V : Entity_Id) is
5482 if Debug_Flag_CC then
5483 w ("Kill_Checks for entity", Int (V));
5486 for J in 1 .. Num_Saved_Checks loop
5487 if Saved_Checks (J).Entity = V then
5488 if Debug_Flag_CC then
5489 w (" Checks killed for saved check ", J);
5492 Saved_Checks (J).Killed := True;
5497 ------------------------------
5498 -- Length_Checks_Suppressed --
5499 ------------------------------
5501 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
5503 if Present (E) and then Checks_May_Be_Suppressed (E) then
5504 return Is_Check_Suppressed (E, Length_Check);
5506 return Scope_Suppress (Length_Check);
5508 end Length_Checks_Suppressed;
5510 --------------------------------
5511 -- Overflow_Checks_Suppressed --
5512 --------------------------------
5514 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
5516 if Present (E) and then Checks_May_Be_Suppressed (E) then
5517 return Is_Check_Suppressed (E, Overflow_Check);
5519 return Scope_Suppress (Overflow_Check);
5521 end Overflow_Checks_Suppressed;
5523 -----------------------------
5524 -- Range_Checks_Suppressed --
5525 -----------------------------
5527 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
5531 -- Note: for now we always suppress range checks on Vax float types,
5532 -- since Gigi does not know how to generate these checks.
5534 if Vax_Float (E) then
5536 elsif Kill_Range_Checks (E) then
5538 elsif Checks_May_Be_Suppressed (E) then
5539 return Is_Check_Suppressed (E, Range_Check);
5543 return Scope_Suppress (Range_Check);
5544 end Range_Checks_Suppressed;
5546 -----------------------------------------
5547 -- Range_Or_Validity_Checks_Suppressed --
5548 -----------------------------------------
5550 -- Note: the coding would be simpler here if we simply made appropriate
5551 -- calls to Range/Validity_Checks_Suppressed, but that would result in
5552 -- duplicated checks which we prefer to avoid.
5554 function Range_Or_Validity_Checks_Suppressed
5555 (Expr : Node_Id) return Boolean
5558 -- Immediate return if scope checks suppressed for either check
5560 if Scope_Suppress (Range_Check) or Scope_Suppress (Validity_Check) then
5564 -- If no expression, that's odd, decide that checks are suppressed,
5565 -- since we don't want anyone trying to do checks in this case, which
5566 -- is most likely the result of some other error.
5572 -- Expression is present, so perform suppress checks on type
5575 Typ : constant Entity_Id := Etype (Expr);
5577 if Vax_Float (Typ) then
5579 elsif Checks_May_Be_Suppressed (Typ)
5580 and then (Is_Check_Suppressed (Typ, Range_Check)
5582 Is_Check_Suppressed (Typ, Validity_Check))
5588 -- If expression is an entity name, perform checks on this entity
5590 if Is_Entity_Name (Expr) then
5592 Ent : constant Entity_Id := Entity (Expr);
5594 if Checks_May_Be_Suppressed (Ent) then
5595 return Is_Check_Suppressed (Ent, Range_Check)
5596 or else Is_Check_Suppressed (Ent, Validity_Check);
5601 -- If we fall through, no checks suppressed
5604 end Range_Or_Validity_Checks_Suppressed;
5610 procedure Remove_Checks (Expr : Node_Id) is
5611 function Process (N : Node_Id) return Traverse_Result;
5612 -- Process a single node during the traversal
5614 procedure Traverse is new Traverse_Proc (Process);
5615 -- The traversal procedure itself
5621 function Process (N : Node_Id) return Traverse_Result is
5623 if Nkind (N) not in N_Subexpr then
5627 Set_Do_Range_Check (N, False);
5631 Traverse (Left_Opnd (N));
5634 when N_Attribute_Reference =>
5635 Set_Do_Overflow_Check (N, False);
5637 when N_Function_Call =>
5638 Set_Do_Tag_Check (N, False);
5641 Set_Do_Overflow_Check (N, False);
5645 Set_Do_Division_Check (N, False);
5648 Set_Do_Length_Check (N, False);
5651 Set_Do_Division_Check (N, False);
5654 Set_Do_Length_Check (N, False);
5657 Set_Do_Division_Check (N, False);
5660 Set_Do_Length_Check (N, False);
5667 Traverse (Left_Opnd (N));
5670 when N_Selected_Component =>
5671 Set_Do_Discriminant_Check (N, False);
5673 when N_Type_Conversion =>
5674 Set_Do_Length_Check (N, False);
5675 Set_Do_Tag_Check (N, False);
5676 Set_Do_Overflow_Check (N, False);
5685 -- Start of processing for Remove_Checks
5691 ----------------------------
5692 -- Selected_Length_Checks --
5693 ----------------------------
5695 function Selected_Length_Checks
5697 Target_Typ : Entity_Id;
5698 Source_Typ : Entity_Id;
5699 Warn_Node : Node_Id) return Check_Result
5701 Loc : constant Source_Ptr := Sloc (Ck_Node);
5704 Expr_Actual : Node_Id;
5706 Cond : Node_Id := Empty;
5707 Do_Access : Boolean := False;
5708 Wnode : Node_Id := Warn_Node;
5709 Ret_Result : Check_Result := (Empty, Empty);
5710 Num_Checks : Natural := 0;
5712 procedure Add_Check (N : Node_Id);
5713 -- Adds the action given to Ret_Result if N is non-Empty
5715 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
5716 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
5717 -- Comments required ???
5719 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
5720 -- True for equal literals and for nodes that denote the same constant
5721 -- entity, even if its value is not a static constant. This includes the
5722 -- case of a discriminal reference within an init proc. Removes some
5723 -- obviously superfluous checks.
5725 function Length_E_Cond
5726 (Exptyp : Entity_Id;
5728 Indx : Nat) return Node_Id;
5729 -- Returns expression to compute:
5730 -- Typ'Length /= Exptyp'Length
5732 function Length_N_Cond
5735 Indx : Nat) return Node_Id;
5736 -- Returns expression to compute:
5737 -- Typ'Length /= Expr'Length
5743 procedure Add_Check (N : Node_Id) is
5747 -- For now, ignore attempt to place more than 2 checks ???
5749 if Num_Checks = 2 then
5753 pragma Assert (Num_Checks <= 1);
5754 Num_Checks := Num_Checks + 1;
5755 Ret_Result (Num_Checks) := N;
5763 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
5764 SE : constant Entity_Id := Scope (E);
5766 E1 : Entity_Id := E;
5769 if Ekind (Scope (E)) = E_Record_Type
5770 and then Has_Discriminants (Scope (E))
5772 N := Build_Discriminal_Subtype_Of_Component (E);
5775 Insert_Action (Ck_Node, N);
5776 E1 := Defining_Identifier (N);
5780 if Ekind (E1) = E_String_Literal_Subtype then
5782 Make_Integer_Literal (Loc,
5783 Intval => String_Literal_Length (E1));
5785 elsif SE /= Standard_Standard
5786 and then Ekind (Scope (SE)) = E_Protected_Type
5787 and then Has_Discriminants (Scope (SE))
5788 and then Has_Completion (Scope (SE))
5789 and then not Inside_Init_Proc
5791 -- If the type whose length is needed is a private component
5792 -- constrained by a discriminant, we must expand the 'Length
5793 -- attribute into an explicit computation, using the discriminal
5794 -- of the current protected operation. This is because the actual
5795 -- type of the prival is constructed after the protected opera-
5796 -- tion has been fully expanded.
5799 Indx_Type : Node_Id;
5802 Do_Expand : Boolean := False;
5805 Indx_Type := First_Index (E);
5807 for J in 1 .. Indx - 1 loop
5808 Next_Index (Indx_Type);
5811 Get_Index_Bounds (Indx_Type, Lo, Hi);
5813 if Nkind (Lo) = N_Identifier
5814 and then Ekind (Entity (Lo)) = E_In_Parameter
5816 Lo := Get_Discriminal (E, Lo);
5820 if Nkind (Hi) = N_Identifier
5821 and then Ekind (Entity (Hi)) = E_In_Parameter
5823 Hi := Get_Discriminal (E, Hi);
5828 if not Is_Entity_Name (Lo) then
5829 Lo := Duplicate_Subexpr_No_Checks (Lo);
5832 if not Is_Entity_Name (Hi) then
5833 Lo := Duplicate_Subexpr_No_Checks (Hi);
5839 Make_Op_Subtract (Loc,
5843 Right_Opnd => Make_Integer_Literal (Loc, 1));
5848 Make_Attribute_Reference (Loc,
5849 Attribute_Name => Name_Length,
5851 New_Occurrence_Of (E1, Loc));
5854 Set_Expressions (N, New_List (
5855 Make_Integer_Literal (Loc, Indx)));
5864 Make_Attribute_Reference (Loc,
5865 Attribute_Name => Name_Length,
5867 New_Occurrence_Of (E1, Loc));
5870 Set_Expressions (N, New_List (
5871 Make_Integer_Literal (Loc, Indx)));
5882 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
5885 Make_Attribute_Reference (Loc,
5886 Attribute_Name => Name_Length,
5888 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
5889 Expressions => New_List (
5890 Make_Integer_Literal (Loc, Indx)));
5897 function Length_E_Cond
5898 (Exptyp : Entity_Id;
5900 Indx : Nat) return Node_Id
5905 Left_Opnd => Get_E_Length (Typ, Indx),
5906 Right_Opnd => Get_E_Length (Exptyp, Indx));
5913 function Length_N_Cond
5916 Indx : Nat) return Node_Id
5921 Left_Opnd => Get_E_Length (Typ, Indx),
5922 Right_Opnd => Get_N_Length (Expr, Indx));
5929 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
5932 (Nkind (L) = N_Integer_Literal
5933 and then Nkind (R) = N_Integer_Literal
5934 and then Intval (L) = Intval (R))
5938 and then Ekind (Entity (L)) = E_Constant
5939 and then ((Is_Entity_Name (R)
5940 and then Entity (L) = Entity (R))
5942 (Nkind (R) = N_Type_Conversion
5943 and then Is_Entity_Name (Expression (R))
5944 and then Entity (L) = Entity (Expression (R)))))
5948 and then Ekind (Entity (R)) = E_Constant
5949 and then Nkind (L) = N_Type_Conversion
5950 and then Is_Entity_Name (Expression (L))
5951 and then Entity (R) = Entity (Expression (L)))
5955 and then Is_Entity_Name (R)
5956 and then Entity (L) = Entity (R)
5957 and then Ekind (Entity (L)) = E_In_Parameter
5958 and then Inside_Init_Proc);
5961 -- Start of processing for Selected_Length_Checks
5964 if not Expander_Active then
5968 if Target_Typ = Any_Type
5969 or else Target_Typ = Any_Composite
5970 or else Raises_Constraint_Error (Ck_Node)
5979 T_Typ := Target_Typ;
5981 if No (Source_Typ) then
5982 S_Typ := Etype (Ck_Node);
5984 S_Typ := Source_Typ;
5987 if S_Typ = Any_Type or else S_Typ = Any_Composite then
5991 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
5992 S_Typ := Designated_Type (S_Typ);
5993 T_Typ := Designated_Type (T_Typ);
5996 -- A simple optimization for the null case
5998 if Known_Null (Ck_Node) then
6003 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6004 if Is_Constrained (T_Typ) then
6006 -- The checking code to be generated will freeze the
6007 -- corresponding array type. However, we must freeze the
6008 -- type now, so that the freeze node does not appear within
6009 -- the generated condional expression, but ahead of it.
6011 Freeze_Before (Ck_Node, T_Typ);
6013 Expr_Actual := Get_Referenced_Object (Ck_Node);
6014 Exptyp := Get_Actual_Subtype (Ck_Node);
6016 if Is_Access_Type (Exptyp) then
6017 Exptyp := Designated_Type (Exptyp);
6020 -- String_Literal case. This needs to be handled specially be-
6021 -- cause no index types are available for string literals. The
6022 -- condition is simply:
6024 -- T_Typ'Length = string-literal-length
6026 if Nkind (Expr_Actual) = N_String_Literal
6027 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
6031 Left_Opnd => Get_E_Length (T_Typ, 1),
6033 Make_Integer_Literal (Loc,
6035 String_Literal_Length (Etype (Expr_Actual))));
6037 -- General array case. Here we have a usable actual subtype for
6038 -- the expression, and the condition is built from the two types
6041 -- T_Typ'Length /= Exptyp'Length or else
6042 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
6043 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
6046 elsif Is_Constrained (Exptyp) then
6048 Ndims : constant Nat := Number_Dimensions (T_Typ);
6061 -- At the library level, we need to ensure that the type of
6062 -- the object is elaborated before the check itself is
6063 -- emitted. This is only done if the object is in the
6064 -- current compilation unit, otherwise the type is frozen
6065 -- and elaborated in its unit.
6067 if Is_Itype (Exptyp)
6069 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
6071 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
6072 and then In_Open_Scopes (Scope (Exptyp))
6074 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
6075 Set_Itype (Ref_Node, Exptyp);
6076 Insert_Action (Ck_Node, Ref_Node);
6079 L_Index := First_Index (T_Typ);
6080 R_Index := First_Index (Exptyp);
6082 for Indx in 1 .. Ndims loop
6083 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6085 Nkind (R_Index) = N_Raise_Constraint_Error)
6087 Get_Index_Bounds (L_Index, L_Low, L_High);
6088 Get_Index_Bounds (R_Index, R_Low, R_High);
6090 -- Deal with compile time length check. Note that we
6091 -- skip this in the access case, because the access
6092 -- value may be null, so we cannot know statically.
6095 and then Compile_Time_Known_Value (L_Low)
6096 and then Compile_Time_Known_Value (L_High)
6097 and then Compile_Time_Known_Value (R_Low)
6098 and then Compile_Time_Known_Value (R_High)
6100 if Expr_Value (L_High) >= Expr_Value (L_Low) then
6101 L_Length := Expr_Value (L_High) -
6102 Expr_Value (L_Low) + 1;
6104 L_Length := UI_From_Int (0);
6107 if Expr_Value (R_High) >= Expr_Value (R_Low) then
6108 R_Length := Expr_Value (R_High) -
6109 Expr_Value (R_Low) + 1;
6111 R_Length := UI_From_Int (0);
6114 if L_Length > R_Length then
6116 (Compile_Time_Constraint_Error
6117 (Wnode, "too few elements for}?", T_Typ));
6119 elsif L_Length < R_Length then
6121 (Compile_Time_Constraint_Error
6122 (Wnode, "too many elements for}?", T_Typ));
6125 -- The comparison for an individual index subtype
6126 -- is omitted if the corresponding index subtypes
6127 -- statically match, since the result is known to
6128 -- be true. Note that this test is worth while even
6129 -- though we do static evaluation, because non-static
6130 -- subtypes can statically match.
6133 Subtypes_Statically_Match
6134 (Etype (L_Index), Etype (R_Index))
6137 (Same_Bounds (L_Low, R_Low)
6138 and then Same_Bounds (L_High, R_High))
6141 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
6150 -- Handle cases where we do not get a usable actual subtype that
6151 -- is constrained. This happens for example in the function call
6152 -- and explicit dereference cases. In these cases, we have to get
6153 -- the length or range from the expression itself, making sure we
6154 -- do not evaluate it more than once.
6156 -- Here Ck_Node is the original expression, or more properly the
6157 -- result of applying Duplicate_Expr to the original tree, forcing
6158 -- the result to be a name.
6162 Ndims : constant Nat := Number_Dimensions (T_Typ);
6165 -- Build the condition for the explicit dereference case
6167 for Indx in 1 .. Ndims loop
6169 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
6176 -- Construct the test and insert into the tree
6178 if Present (Cond) then
6180 Cond := Guard_Access (Cond, Loc, Ck_Node);
6184 (Make_Raise_Constraint_Error (Loc,
6186 Reason => CE_Length_Check_Failed));
6190 end Selected_Length_Checks;
6192 ---------------------------
6193 -- Selected_Range_Checks --
6194 ---------------------------
6196 function Selected_Range_Checks
6198 Target_Typ : Entity_Id;
6199 Source_Typ : Entity_Id;
6200 Warn_Node : Node_Id) return Check_Result
6202 Loc : constant Source_Ptr := Sloc (Ck_Node);
6205 Expr_Actual : Node_Id;
6207 Cond : Node_Id := Empty;
6208 Do_Access : Boolean := False;
6209 Wnode : Node_Id := Warn_Node;
6210 Ret_Result : Check_Result := (Empty, Empty);
6211 Num_Checks : Integer := 0;
6213 procedure Add_Check (N : Node_Id);
6214 -- Adds the action given to Ret_Result if N is non-Empty
6216 function Discrete_Range_Cond
6218 Typ : Entity_Id) return Node_Id;
6219 -- Returns expression to compute:
6220 -- Low_Bound (Expr) < Typ'First
6222 -- High_Bound (Expr) > Typ'Last
6224 function Discrete_Expr_Cond
6226 Typ : Entity_Id) return Node_Id;
6227 -- Returns expression to compute:
6232 function Get_E_First_Or_Last
6235 Nam : Name_Id) return Node_Id;
6236 -- Returns expression to compute:
6237 -- E'First or E'Last
6239 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
6240 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
6241 -- Returns expression to compute:
6242 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
6244 function Range_E_Cond
6245 (Exptyp : Entity_Id;
6249 -- Returns expression to compute:
6250 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
6252 function Range_Equal_E_Cond
6253 (Exptyp : Entity_Id;
6255 Indx : Nat) return Node_Id;
6256 -- Returns expression to compute:
6257 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
6259 function Range_N_Cond
6262 Indx : Nat) return Node_Id;
6263 -- Return expression to compute:
6264 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
6270 procedure Add_Check (N : Node_Id) is
6274 -- For now, ignore attempt to place more than 2 checks ???
6276 if Num_Checks = 2 then
6280 pragma Assert (Num_Checks <= 1);
6281 Num_Checks := Num_Checks + 1;
6282 Ret_Result (Num_Checks) := N;
6286 -------------------------
6287 -- Discrete_Expr_Cond --
6288 -------------------------
6290 function Discrete_Expr_Cond
6292 Typ : Entity_Id) return Node_Id
6300 Convert_To (Base_Type (Typ),
6301 Duplicate_Subexpr_No_Checks (Expr)),
6303 Convert_To (Base_Type (Typ),
6304 Get_E_First_Or_Last (Typ, 0, Name_First))),
6309 Convert_To (Base_Type (Typ),
6310 Duplicate_Subexpr_No_Checks (Expr)),
6314 Get_E_First_Or_Last (Typ, 0, Name_Last))));
6315 end Discrete_Expr_Cond;
6317 -------------------------
6318 -- Discrete_Range_Cond --
6319 -------------------------
6321 function Discrete_Range_Cond
6323 Typ : Entity_Id) return Node_Id
6325 LB : Node_Id := Low_Bound (Expr);
6326 HB : Node_Id := High_Bound (Expr);
6328 Left_Opnd : Node_Id;
6329 Right_Opnd : Node_Id;
6332 if Nkind (LB) = N_Identifier
6333 and then Ekind (Entity (LB)) = E_Discriminant
6335 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6338 if Nkind (HB) = N_Identifier
6339 and then Ekind (Entity (HB)) = E_Discriminant
6341 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6348 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
6352 (Base_Type (Typ), Get_E_First_Or_Last (Typ, 0, Name_First)));
6354 if Base_Type (Typ) = Typ then
6357 elsif Compile_Time_Known_Value (High_Bound (Scalar_Range (Typ)))
6359 Compile_Time_Known_Value (High_Bound (Scalar_Range
6362 if Is_Floating_Point_Type (Typ) then
6363 if Expr_Value_R (High_Bound (Scalar_Range (Typ))) =
6364 Expr_Value_R (High_Bound (Scalar_Range (Base_Type (Typ))))
6370 if Expr_Value (High_Bound (Scalar_Range (Typ))) =
6371 Expr_Value (High_Bound (Scalar_Range (Base_Type (Typ))))
6382 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
6387 Get_E_First_Or_Last (Typ, 0, Name_Last)));
6389 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
6390 end Discrete_Range_Cond;
6392 -------------------------
6393 -- Get_E_First_Or_Last --
6394 -------------------------
6396 function Get_E_First_Or_Last
6399 Nam : Name_Id) return Node_Id
6407 if Is_Array_Type (E) then
6408 N := First_Index (E);
6410 for J in 2 .. Indx loop
6415 N := Scalar_Range (E);
6418 if Nkind (N) = N_Subtype_Indication then
6419 LB := Low_Bound (Range_Expression (Constraint (N)));
6420 HB := High_Bound (Range_Expression (Constraint (N)));
6422 elsif Is_Entity_Name (N) then
6423 LB := Type_Low_Bound (Etype (N));
6424 HB := Type_High_Bound (Etype (N));
6427 LB := Low_Bound (N);
6428 HB := High_Bound (N);
6431 if Nam = Name_First then
6437 if Nkind (Bound) = N_Identifier
6438 and then Ekind (Entity (Bound)) = E_Discriminant
6440 -- If this is a task discriminant, and we are the body, we must
6441 -- retrieve the corresponding body discriminal. This is another
6442 -- consequence of the early creation of discriminals, and the
6443 -- need to generate constraint checks before their declarations
6444 -- are made visible.
6446 if Is_Concurrent_Record_Type (Scope (Entity (Bound))) then
6448 Tsk : constant Entity_Id :=
6449 Corresponding_Concurrent_Type
6450 (Scope (Entity (Bound)));
6454 if In_Open_Scopes (Tsk)
6455 and then Has_Completion (Tsk)
6457 -- Find discriminant of original task, and use its
6458 -- current discriminal, which is the renaming within
6461 Disc := First_Discriminant (Tsk);
6462 while Present (Disc) loop
6463 if Chars (Disc) = Chars (Entity (Bound)) then
6464 Set_Scope (Discriminal (Disc), Tsk);
6465 return New_Occurrence_Of (Discriminal (Disc), Loc);
6468 Next_Discriminant (Disc);
6471 -- That loop should always succeed in finding a matching
6472 -- entry and returning. Fatal error if not.
6474 raise Program_Error;
6478 New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6482 return New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6485 elsif Nkind (Bound) = N_Identifier
6486 and then Ekind (Entity (Bound)) = E_In_Parameter
6487 and then not Inside_Init_Proc
6489 return Get_Discriminal (E, Bound);
6491 elsif Nkind (Bound) = N_Integer_Literal then
6492 return Make_Integer_Literal (Loc, Intval (Bound));
6494 -- Case of a bound rewritten to an N_Raise_Constraint_Error node
6495 -- because it is an out-of-range value. Duplicate_Subexpr cannot be
6496 -- called on this node because an N_Raise_Constraint_Error is not
6497 -- side effect free, and we may not assume that we are in the proper
6498 -- context to remove side effects on it at the point of reference.
6500 elsif Nkind (Bound) = N_Raise_Constraint_Error then
6501 return New_Copy_Tree (Bound);
6504 return Duplicate_Subexpr_No_Checks (Bound);
6506 end Get_E_First_Or_Last;
6512 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
6515 Make_Attribute_Reference (Loc,
6516 Attribute_Name => Name_First,
6518 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6519 Expressions => New_List (
6520 Make_Integer_Literal (Loc, Indx)));
6527 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
6530 Make_Attribute_Reference (Loc,
6531 Attribute_Name => Name_Last,
6533 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6534 Expressions => New_List (
6535 Make_Integer_Literal (Loc, Indx)));
6542 function Range_E_Cond
6543 (Exptyp : Entity_Id;
6545 Indx : Nat) return Node_Id
6552 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6553 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6557 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6558 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6561 ------------------------
6562 -- Range_Equal_E_Cond --
6563 ------------------------
6565 function Range_Equal_E_Cond
6566 (Exptyp : Entity_Id;
6568 Indx : Nat) return Node_Id
6575 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6576 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6579 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6580 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6581 end Range_Equal_E_Cond;
6587 function Range_N_Cond
6590 Indx : Nat) return Node_Id
6597 Left_Opnd => Get_N_First (Expr, Indx),
6598 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6602 Left_Opnd => Get_N_Last (Expr, Indx),
6603 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6606 -- Start of processing for Selected_Range_Checks
6609 if not Expander_Active then
6613 if Target_Typ = Any_Type
6614 or else Target_Typ = Any_Composite
6615 or else Raises_Constraint_Error (Ck_Node)
6624 T_Typ := Target_Typ;
6626 if No (Source_Typ) then
6627 S_Typ := Etype (Ck_Node);
6629 S_Typ := Source_Typ;
6632 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6636 -- The order of evaluating T_Typ before S_Typ seems to be critical
6637 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
6638 -- in, and since Node can be an N_Range node, it might be invalid.
6639 -- Should there be an assert check somewhere for taking the Etype of
6640 -- an N_Range node ???
6642 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6643 S_Typ := Designated_Type (S_Typ);
6644 T_Typ := Designated_Type (T_Typ);
6647 -- A simple optimization for the null case
6649 if Known_Null (Ck_Node) then
6654 -- For an N_Range Node, check for a null range and then if not
6655 -- null generate a range check action.
6657 if Nkind (Ck_Node) = N_Range then
6659 -- There's no point in checking a range against itself
6661 if Ck_Node = Scalar_Range (T_Typ) then
6666 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
6667 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
6668 LB : constant Node_Id := Low_Bound (Ck_Node);
6669 HB : constant Node_Id := High_Bound (Ck_Node);
6670 Null_Range : Boolean;
6672 Out_Of_Range_L : Boolean;
6673 Out_Of_Range_H : Boolean;
6676 -- Check for case where everything is static and we can
6677 -- do the check at compile time. This is skipped if we
6678 -- have an access type, since the access value may be null.
6680 -- ??? This code can be improved since you only need to know
6681 -- that the two respective bounds (LB & T_LB or HB & T_HB)
6682 -- are known at compile time to emit pertinent messages.
6684 if Compile_Time_Known_Value (LB)
6685 and then Compile_Time_Known_Value (HB)
6686 and then Compile_Time_Known_Value (T_LB)
6687 and then Compile_Time_Known_Value (T_HB)
6688 and then not Do_Access
6690 -- Floating-point case
6692 if Is_Floating_Point_Type (S_Typ) then
6693 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
6695 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
6697 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
6700 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
6702 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
6704 -- Fixed or discrete type case
6707 Null_Range := Expr_Value (HB) < Expr_Value (LB);
6709 (Expr_Value (LB) < Expr_Value (T_LB))
6711 (Expr_Value (LB) > Expr_Value (T_HB));
6714 (Expr_Value (HB) > Expr_Value (T_HB))
6716 (Expr_Value (HB) < Expr_Value (T_LB));
6719 if not Null_Range then
6720 if Out_Of_Range_L then
6721 if No (Warn_Node) then
6723 (Compile_Time_Constraint_Error
6724 (Low_Bound (Ck_Node),
6725 "static value out of range of}?", T_Typ));
6729 (Compile_Time_Constraint_Error
6731 "static range out of bounds of}?", T_Typ));
6735 if Out_Of_Range_H then
6736 if No (Warn_Node) then
6738 (Compile_Time_Constraint_Error
6739 (High_Bound (Ck_Node),
6740 "static value out of range of}?", T_Typ));
6744 (Compile_Time_Constraint_Error
6746 "static range out of bounds of}?", T_Typ));
6754 LB : Node_Id := Low_Bound (Ck_Node);
6755 HB : Node_Id := High_Bound (Ck_Node);
6758 -- If either bound is a discriminant and we are within the
6759 -- record declaration, it is a use of the discriminant in a
6760 -- constraint of a component, and nothing can be checked
6761 -- here. The check will be emitted within the init proc.
6762 -- Before then, the discriminal has no real meaning.
6763 -- Similarly, if the entity is a discriminal, there is no
6764 -- check to perform yet.
6766 -- The same holds within a discriminated synchronized type,
6767 -- where the discriminant may constrain a component or an
6770 if Nkind (LB) = N_Identifier
6771 and then Denotes_Discriminant (LB, True)
6773 if Current_Scope = Scope (Entity (LB))
6774 or else Is_Concurrent_Type (Current_Scope)
6775 or else Ekind (Entity (LB)) /= E_Discriminant
6780 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6784 if Nkind (HB) = N_Identifier
6785 and then Denotes_Discriminant (HB, True)
6787 if Current_Scope = Scope (Entity (HB))
6788 or else Is_Concurrent_Type (Current_Scope)
6789 or else Ekind (Entity (HB)) /= E_Discriminant
6794 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6798 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
6799 Set_Paren_Count (Cond, 1);
6805 Left_Opnd => Duplicate_Subexpr_No_Checks (HB),
6806 Right_Opnd => Duplicate_Subexpr_No_Checks (LB)),
6807 Right_Opnd => Cond);
6812 elsif Is_Scalar_Type (S_Typ) then
6814 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
6815 -- except the above simply sets a flag in the node and lets
6816 -- gigi generate the check base on the Etype of the expression.
6817 -- Sometimes, however we want to do a dynamic check against an
6818 -- arbitrary target type, so we do that here.
6820 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
6821 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6823 -- For literals, we can tell if the constraint error will be
6824 -- raised at compile time, so we never need a dynamic check, but
6825 -- if the exception will be raised, then post the usual warning,
6826 -- and replace the literal with a raise constraint error
6827 -- expression. As usual, skip this for access types
6829 elsif Compile_Time_Known_Value (Ck_Node)
6830 and then not Do_Access
6833 LB : constant Node_Id := Type_Low_Bound (T_Typ);
6834 UB : constant Node_Id := Type_High_Bound (T_Typ);
6836 Out_Of_Range : Boolean;
6837 Static_Bounds : constant Boolean :=
6838 Compile_Time_Known_Value (LB)
6839 and Compile_Time_Known_Value (UB);
6842 -- Following range tests should use Sem_Eval routine ???
6844 if Static_Bounds then
6845 if Is_Floating_Point_Type (S_Typ) then
6847 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
6849 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
6851 else -- fixed or discrete type
6853 Expr_Value (Ck_Node) < Expr_Value (LB)
6855 Expr_Value (Ck_Node) > Expr_Value (UB);
6858 -- Bounds of the type are static and the literal is
6859 -- out of range so make a warning message.
6861 if Out_Of_Range then
6862 if No (Warn_Node) then
6864 (Compile_Time_Constraint_Error
6866 "static value out of range of}?", T_Typ));
6870 (Compile_Time_Constraint_Error
6872 "static value out of range of}?", T_Typ));
6877 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6881 -- Here for the case of a non-static expression, we need a runtime
6882 -- check unless the source type range is guaranteed to be in the
6883 -- range of the target type.
6886 if not In_Subrange_Of (S_Typ, T_Typ) then
6887 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6892 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6893 if Is_Constrained (T_Typ) then
6895 Expr_Actual := Get_Referenced_Object (Ck_Node);
6896 Exptyp := Get_Actual_Subtype (Expr_Actual);
6898 if Is_Access_Type (Exptyp) then
6899 Exptyp := Designated_Type (Exptyp);
6902 -- String_Literal case. This needs to be handled specially be-
6903 -- cause no index types are available for string literals. The
6904 -- condition is simply:
6906 -- T_Typ'Length = string-literal-length
6908 if Nkind (Expr_Actual) = N_String_Literal then
6911 -- General array case. Here we have a usable actual subtype for
6912 -- the expression, and the condition is built from the two types
6914 -- T_Typ'First < Exptyp'First or else
6915 -- T_Typ'Last > Exptyp'Last or else
6916 -- T_Typ'First(1) < Exptyp'First(1) or else
6917 -- T_Typ'Last(1) > Exptyp'Last(1) or else
6920 elsif Is_Constrained (Exptyp) then
6922 Ndims : constant Nat := Number_Dimensions (T_Typ);
6928 L_Index := First_Index (T_Typ);
6929 R_Index := First_Index (Exptyp);
6931 for Indx in 1 .. Ndims loop
6932 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6934 Nkind (R_Index) = N_Raise_Constraint_Error)
6936 -- Deal with compile time length check. Note that we
6937 -- skip this in the access case, because the access
6938 -- value may be null, so we cannot know statically.
6941 Subtypes_Statically_Match
6942 (Etype (L_Index), Etype (R_Index))
6944 -- If the target type is constrained then we
6945 -- have to check for exact equality of bounds
6946 -- (required for qualified expressions).
6948 if Is_Constrained (T_Typ) then
6951 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
6954 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
6965 -- Handle cases where we do not get a usable actual subtype that
6966 -- is constrained. This happens for example in the function call
6967 -- and explicit dereference cases. In these cases, we have to get
6968 -- the length or range from the expression itself, making sure we
6969 -- do not evaluate it more than once.
6971 -- Here Ck_Node is the original expression, or more properly the
6972 -- result of applying Duplicate_Expr to the original tree,
6973 -- forcing the result to be a name.
6977 Ndims : constant Nat := Number_Dimensions (T_Typ);
6980 -- Build the condition for the explicit dereference case
6982 for Indx in 1 .. Ndims loop
6984 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
6991 -- For a conversion to an unconstrained array type, generate an
6992 -- Action to check that the bounds of the source value are within
6993 -- the constraints imposed by the target type (RM 4.6(38)). No
6994 -- check is needed for a conversion to an access to unconstrained
6995 -- array type, as 4.6(24.15/2) requires the designated subtypes
6996 -- of the two access types to statically match.
6998 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
6999 and then not Do_Access
7002 Opnd_Index : Node_Id;
7003 Targ_Index : Node_Id;
7004 Opnd_Range : Node_Id;
7007 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
7008 Targ_Index := First_Index (T_Typ);
7009 while Present (Opnd_Index) loop
7011 -- If the index is a range, use its bounds. If it is an
7012 -- entity (as will be the case if it is a named subtype
7013 -- or an itype created for a slice) retrieve its range.
7015 if Is_Entity_Name (Opnd_Index)
7016 and then Is_Type (Entity (Opnd_Index))
7018 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
7020 Opnd_Range := Opnd_Index;
7023 if Nkind (Opnd_Range) = N_Range then
7025 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7026 Assume_Valid => True)
7029 (High_Bound (Opnd_Range), Etype (Targ_Index),
7030 Assume_Valid => True)
7034 -- If null range, no check needed
7037 Compile_Time_Known_Value (High_Bound (Opnd_Range))
7039 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
7041 Expr_Value (High_Bound (Opnd_Range)) <
7042 Expr_Value (Low_Bound (Opnd_Range))
7046 elsif Is_Out_Of_Range
7047 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7048 Assume_Valid => True)
7051 (High_Bound (Opnd_Range), Etype (Targ_Index),
7052 Assume_Valid => True)
7055 (Compile_Time_Constraint_Error
7056 (Wnode, "value out of range of}?", T_Typ));
7062 (Opnd_Range, Etype (Targ_Index)));
7066 Next_Index (Opnd_Index);
7067 Next_Index (Targ_Index);
7074 -- Construct the test and insert into the tree
7076 if Present (Cond) then
7078 Cond := Guard_Access (Cond, Loc, Ck_Node);
7082 (Make_Raise_Constraint_Error (Loc,
7084 Reason => CE_Range_Check_Failed));
7088 end Selected_Range_Checks;
7090 -------------------------------
7091 -- Storage_Checks_Suppressed --
7092 -------------------------------
7094 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
7096 if Present (E) and then Checks_May_Be_Suppressed (E) then
7097 return Is_Check_Suppressed (E, Storage_Check);
7099 return Scope_Suppress (Storage_Check);
7101 end Storage_Checks_Suppressed;
7103 ---------------------------
7104 -- Tag_Checks_Suppressed --
7105 ---------------------------
7107 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
7110 if Kill_Tag_Checks (E) then
7112 elsif Checks_May_Be_Suppressed (E) then
7113 return Is_Check_Suppressed (E, Tag_Check);
7117 return Scope_Suppress (Tag_Check);
7118 end Tag_Checks_Suppressed;
7120 --------------------------
7121 -- Validity_Check_Range --
7122 --------------------------
7124 procedure Validity_Check_Range (N : Node_Id) is
7126 if Validity_Checks_On and Validity_Check_Operands then
7127 if Nkind (N) = N_Range then
7128 Ensure_Valid (Low_Bound (N));
7129 Ensure_Valid (High_Bound (N));
7132 end Validity_Check_Range;
7134 --------------------------------
7135 -- Validity_Checks_Suppressed --
7136 --------------------------------
7138 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
7140 if Present (E) and then Checks_May_Be_Suppressed (E) then
7141 return Is_Check_Suppressed (E, Validity_Check);
7143 return Scope_Suppress (Validity_Check);
7145 end Validity_Checks_Suppressed;