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 has an
489 -- associated extra access level parameter and when the level of the
490 -- type is less deep than the level of the access parameter, and
491 -- accessibility checks are not suppressed.
493 elsif Present (Param_Ent)
494 and then Present (Extra_Accessibility (Param_Ent))
495 and then UI_Gt (Object_Access_Level (N), Type_Access_Level (Typ))
496 and then not Accessibility_Checks_Suppressed (Param_Ent)
497 and then not Accessibility_Checks_Suppressed (Typ)
500 New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc);
503 Make_Integer_Literal (Loc, Type_Access_Level (Typ));
505 -- Raise Program_Error if the accessibility level of the access
506 -- parameter is deeper than the level of the target access type.
508 Insert_Action (Insert_Node,
509 Make_Raise_Program_Error (Loc,
512 Left_Opnd => Param_Level,
513 Right_Opnd => Type_Level),
514 Reason => PE_Accessibility_Check_Failed));
516 Analyze_And_Resolve (N);
518 end Apply_Accessibility_Check;
520 --------------------------------
521 -- Apply_Address_Clause_Check --
522 --------------------------------
524 procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is
525 AC : constant Node_Id := Address_Clause (E);
526 Loc : constant Source_Ptr := Sloc (AC);
527 Typ : constant Entity_Id := Etype (E);
528 Aexp : constant Node_Id := Expression (AC);
531 -- Address expression (not necessarily the same as Aexp, for example
532 -- when Aexp is a reference to a constant, in which case Expr gets
533 -- reset to reference the value expression of the constant.
535 procedure Compile_Time_Bad_Alignment;
536 -- Post error warnings when alignment is known to be incompatible. Note
537 -- that we do not go as far as inserting a raise of Program_Error since
538 -- this is an erroneous case, and it may happen that we are lucky and an
539 -- underaligned address turns out to be OK after all.
541 --------------------------------
542 -- Compile_Time_Bad_Alignment --
543 --------------------------------
545 procedure Compile_Time_Bad_Alignment is
547 if Address_Clause_Overlay_Warnings then
549 ("?specified address for& may be inconsistent with alignment ",
552 ("\?program execution may be erroneous (RM 13.3(27))",
554 Set_Address_Warning_Posted (AC);
556 end Compile_Time_Bad_Alignment;
558 -- Start of processing for Apply_Address_Clause_Check
561 -- See if alignment check needed. Note that we never need a check if the
562 -- maximum alignment is one, since the check will always succeed.
564 -- Note: we do not check for checks suppressed here, since that check
565 -- was done in Sem_Ch13 when the address clause was processed. We are
566 -- only called if checks were not suppressed. The reason for this is
567 -- that we have to delay the call to Apply_Alignment_Check till freeze
568 -- time (so that all types etc are elaborated), but we have to check
569 -- the status of check suppressing at the point of the address clause.
572 or else not Check_Address_Alignment (AC)
573 or else Maximum_Alignment = 1
578 -- Obtain expression from address clause
580 Expr := Expression (AC);
582 -- The following loop digs for the real expression to use in the check
585 -- For constant, get constant expression
587 if Is_Entity_Name (Expr)
588 and then Ekind (Entity (Expr)) = E_Constant
590 Expr := Constant_Value (Entity (Expr));
592 -- For unchecked conversion, get result to convert
594 elsif Nkind (Expr) = N_Unchecked_Type_Conversion then
595 Expr := Expression (Expr);
597 -- For (common case) of To_Address call, get argument
599 elsif Nkind (Expr) = N_Function_Call
600 and then Is_Entity_Name (Name (Expr))
601 and then Is_RTE (Entity (Name (Expr)), RE_To_Address)
603 Expr := First (Parameter_Associations (Expr));
605 if Nkind (Expr) = N_Parameter_Association then
606 Expr := Explicit_Actual_Parameter (Expr);
609 -- We finally have the real expression
616 -- See if we know that Expr has a bad alignment at compile time
618 if Compile_Time_Known_Value (Expr)
619 and then (Known_Alignment (E) or else Known_Alignment (Typ))
622 AL : Uint := Alignment (Typ);
625 -- The object alignment might be more restrictive than the
628 if Known_Alignment (E) then
632 if Expr_Value (Expr) mod AL /= 0 then
633 Compile_Time_Bad_Alignment;
639 -- If the expression has the form X'Address, then we can find out if
640 -- the object X has an alignment that is compatible with the object E.
641 -- If it hasn't or we don't know, we defer issuing the warning until
642 -- the end of the compilation to take into account back end annotations.
644 elsif Nkind (Expr) = N_Attribute_Reference
645 and then Attribute_Name (Expr) = Name_Address
646 and then Has_Compatible_Alignment (E, Prefix (Expr)) = Known_Compatible
651 -- Here we do not know if the value is acceptable. Stricly we don't have
652 -- to do anything, since if the alignment is bad, we have an erroneous
653 -- program. However we are allowed to check for erroneous conditions and
654 -- we decide to do this by default if the check is not suppressed.
656 -- However, don't do the check if elaboration code is unwanted
658 if Restriction_Active (No_Elaboration_Code) then
661 -- Generate a check to raise PE if alignment may be inappropriate
664 -- If the original expression is a non-static constant, use the
665 -- name of the constant itself rather than duplicating its
666 -- defining expression, which was extracted above.
668 -- Note: Expr is empty if the address-clause is applied to in-mode
669 -- actuals (allowed by 13.1(22)).
671 if not Present (Expr)
673 (Is_Entity_Name (Expression (AC))
674 and then Ekind (Entity (Expression (AC))) = E_Constant
675 and then Nkind (Parent (Entity (Expression (AC))))
676 = N_Object_Declaration)
678 Expr := New_Copy_Tree (Expression (AC));
680 Remove_Side_Effects (Expr);
683 Insert_After_And_Analyze (N,
684 Make_Raise_Program_Error (Loc,
691 (RTE (RE_Integer_Address), Expr),
693 Make_Attribute_Reference (Loc,
694 Prefix => New_Occurrence_Of (E, Loc),
695 Attribute_Name => Name_Alignment)),
696 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
697 Reason => PE_Misaligned_Address_Value),
698 Suppress => All_Checks);
703 -- If we have some missing run time component in configurable run time
704 -- mode then just skip the check (it is not required in any case).
706 when RE_Not_Available =>
708 end Apply_Address_Clause_Check;
710 -------------------------------------
711 -- Apply_Arithmetic_Overflow_Check --
712 -------------------------------------
714 -- This routine is called only if the type is an integer type, and a
715 -- software arithmetic overflow check may be needed for op (add, subtract,
716 -- or multiply). This check is performed only if Software_Overflow_Checking
717 -- is enabled and Do_Overflow_Check is set. In this case we expand the
718 -- operation into a more complex sequence of tests that ensures that
719 -- overflow is properly caught.
721 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
722 Loc : constant Source_Ptr := Sloc (N);
723 Typ : Entity_Id := Etype (N);
724 Rtyp : Entity_Id := Root_Type (Typ);
727 -- An interesting special case. If the arithmetic operation appears as
728 -- the operand of a type conversion:
732 -- and all the following conditions apply:
734 -- arithmetic operation is for a signed integer type
735 -- target type type1 is a static integer subtype
736 -- range of x and y are both included in the range of type1
737 -- range of x op y is included in the range of type1
738 -- size of type1 is at least twice the result size of op
740 -- then we don't do an overflow check in any case, instead we transform
741 -- the operation so that we end up with:
743 -- type1 (type1 (x) op type1 (y))
745 -- This avoids intermediate overflow before the conversion. It is
746 -- explicitly permitted by RM 3.5.4(24):
748 -- For the execution of a predefined operation of a signed integer
749 -- type, the implementation need not raise Constraint_Error if the
750 -- result is outside the base range of the type, so long as the
751 -- correct result is produced.
753 -- It's hard to imagine that any programmer counts on the exception
754 -- being raised in this case, and in any case it's wrong coding to
755 -- have this expectation, given the RM permission. Furthermore, other
756 -- Ada compilers do allow such out of range results.
758 -- Note that we do this transformation even if overflow checking is
759 -- off, since this is precisely about giving the "right" result and
760 -- avoiding the need for an overflow check.
762 if Is_Signed_Integer_Type (Typ)
763 and then Nkind (Parent (N)) = N_Type_Conversion
766 Target_Type : constant Entity_Id :=
767 Base_Type (Entity (Subtype_Mark (Parent (N))));
781 if Is_Integer_Type (Target_Type)
782 and then RM_Size (Root_Type (Target_Type)) >= 2 * RM_Size (Rtyp)
784 Tlo := Expr_Value (Type_Low_Bound (Target_Type));
785 Thi := Expr_Value (Type_High_Bound (Target_Type));
788 (Left_Opnd (N), LOK, Llo, Lhi, Assume_Valid => True);
790 (Right_Opnd (N), ROK, Rlo, Rhi, Assume_Valid => True);
793 and then Tlo <= Llo and then Lhi <= Thi
794 and then Tlo <= Rlo and then Rhi <= Thi
796 Determine_Range (N, VOK, Vlo, Vhi, Assume_Valid => True);
798 if VOK and then Tlo <= Vlo and then Vhi <= Thi then
799 Rewrite (Left_Opnd (N),
800 Make_Type_Conversion (Loc,
801 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
802 Expression => Relocate_Node (Left_Opnd (N))));
804 Rewrite (Right_Opnd (N),
805 Make_Type_Conversion (Loc,
806 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
807 Expression => Relocate_Node (Right_Opnd (N))));
809 Set_Etype (N, Target_Type);
811 Rtyp := Root_Type (Typ);
812 Analyze_And_Resolve (Left_Opnd (N), Target_Type);
813 Analyze_And_Resolve (Right_Opnd (N), Target_Type);
815 -- Given that the target type is twice the size of the
816 -- source type, overflow is now impossible, so we can
817 -- safely kill the overflow check and return.
819 Set_Do_Overflow_Check (N, False);
827 -- Now see if an overflow check is required
830 Siz : constant Int := UI_To_Int (Esize (Rtyp));
831 Dsiz : constant Int := Siz * 2;
838 -- Skip check if back end does overflow checks, or the overflow flag
839 -- is not set anyway, or we are not doing code expansion.
841 -- Special case CLI target, where arithmetic overflow checks can be
842 -- performed for integer and long_integer
844 if Backend_Overflow_Checks_On_Target
845 or else not Do_Overflow_Check (N)
846 or else not Expander_Active
848 (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
853 -- Otherwise, generate the full general code for front end overflow
854 -- detection, which works by doing arithmetic in a larger type:
860 -- Typ (Checktyp (x) op Checktyp (y));
862 -- where Typ is the type of the original expression, and Checktyp is
863 -- an integer type of sufficient length to hold the largest possible
866 -- If the size of check type exceeds the size of Long_Long_Integer,
867 -- we use a different approach, expanding to:
869 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
871 -- where xxx is Add, Multiply or Subtract as appropriate
873 -- Find check type if one exists
875 if Dsiz <= Standard_Integer_Size then
876 Ctyp := Standard_Integer;
878 elsif Dsiz <= Standard_Long_Long_Integer_Size then
879 Ctyp := Standard_Long_Long_Integer;
881 -- No check type exists, use runtime call
884 if Nkind (N) = N_Op_Add then
885 Cent := RE_Add_With_Ovflo_Check;
887 elsif Nkind (N) = N_Op_Multiply then
888 Cent := RE_Multiply_With_Ovflo_Check;
891 pragma Assert (Nkind (N) = N_Op_Subtract);
892 Cent := RE_Subtract_With_Ovflo_Check;
897 Make_Function_Call (Loc,
898 Name => New_Reference_To (RTE (Cent), Loc),
899 Parameter_Associations => New_List (
900 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
901 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
903 Analyze_And_Resolve (N, Typ);
907 -- If we fall through, we have the case where we do the arithmetic
908 -- in the next higher type and get the check by conversion. In these
909 -- cases Ctyp is set to the type to be used as the check type.
911 Opnod := Relocate_Node (N);
913 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
916 Set_Etype (Opnd, Ctyp);
917 Set_Analyzed (Opnd, True);
918 Set_Left_Opnd (Opnod, Opnd);
920 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
923 Set_Etype (Opnd, Ctyp);
924 Set_Analyzed (Opnd, True);
925 Set_Right_Opnd (Opnod, Opnd);
927 -- The type of the operation changes to the base type of the check
928 -- type, and we reset the overflow check indication, since clearly no
929 -- overflow is possible now that we are using a double length type.
930 -- We also set the Analyzed flag to avoid a recursive attempt to
933 Set_Etype (Opnod, Base_Type (Ctyp));
934 Set_Do_Overflow_Check (Opnod, False);
935 Set_Analyzed (Opnod, True);
937 -- Now build the outer conversion
939 Opnd := OK_Convert_To (Typ, Opnod);
941 Set_Etype (Opnd, Typ);
943 -- In the discrete type case, we directly generate the range check
944 -- for the outer operand. This range check will implement the
945 -- required overflow check.
947 if Is_Discrete_Type (Typ) then
950 (Expression (N), Typ, CE_Overflow_Check_Failed);
952 -- For other types, we enable overflow checking on the conversion,
953 -- after setting the node as analyzed to prevent recursive attempts
954 -- to expand the conversion node.
957 Set_Analyzed (Opnd, True);
958 Enable_Overflow_Check (Opnd);
963 when RE_Not_Available =>
966 end Apply_Arithmetic_Overflow_Check;
968 ----------------------------
969 -- Apply_Constraint_Check --
970 ----------------------------
972 procedure Apply_Constraint_Check
975 No_Sliding : Boolean := False)
977 Desig_Typ : Entity_Id;
980 if Inside_A_Generic then
983 elsif Is_Scalar_Type (Typ) then
984 Apply_Scalar_Range_Check (N, Typ);
986 elsif Is_Array_Type (Typ) then
988 -- A useful optimization: an aggregate with only an others clause
989 -- always has the right bounds.
991 if Nkind (N) = N_Aggregate
992 and then No (Expressions (N))
994 (First (Choices (First (Component_Associations (N)))))
1000 if Is_Constrained (Typ) then
1001 Apply_Length_Check (N, Typ);
1004 Apply_Range_Check (N, Typ);
1007 Apply_Range_Check (N, Typ);
1010 elsif (Is_Record_Type (Typ)
1011 or else Is_Private_Type (Typ))
1012 and then Has_Discriminants (Base_Type (Typ))
1013 and then Is_Constrained (Typ)
1015 Apply_Discriminant_Check (N, Typ);
1017 elsif Is_Access_Type (Typ) then
1019 Desig_Typ := Designated_Type (Typ);
1021 -- No checks necessary if expression statically null
1023 if Known_Null (N) then
1024 if Can_Never_Be_Null (Typ) then
1025 Install_Null_Excluding_Check (N);
1028 -- No sliding possible on access to arrays
1030 elsif Is_Array_Type (Desig_Typ) then
1031 if Is_Constrained (Desig_Typ) then
1032 Apply_Length_Check (N, Typ);
1035 Apply_Range_Check (N, Typ);
1037 elsif Has_Discriminants (Base_Type (Desig_Typ))
1038 and then Is_Constrained (Desig_Typ)
1040 Apply_Discriminant_Check (N, Typ);
1043 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1044 -- this check if the constraint node is illegal, as shown by having
1045 -- an error posted. This additional guard prevents cascaded errors
1046 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1048 if Can_Never_Be_Null (Typ)
1049 and then not Can_Never_Be_Null (Etype (N))
1050 and then not Error_Posted (N)
1052 Install_Null_Excluding_Check (N);
1055 end Apply_Constraint_Check;
1057 ------------------------------
1058 -- Apply_Discriminant_Check --
1059 ------------------------------
1061 procedure Apply_Discriminant_Check
1064 Lhs : Node_Id := Empty)
1066 Loc : constant Source_Ptr := Sloc (N);
1067 Do_Access : constant Boolean := Is_Access_Type (Typ);
1068 S_Typ : Entity_Id := Etype (N);
1072 function Is_Aliased_Unconstrained_Component return Boolean;
1073 -- It is possible for an aliased component to have a nominal
1074 -- unconstrained subtype (through instantiation). If this is a
1075 -- discriminated component assigned in the expansion of an aggregate
1076 -- in an initialization, the check must be suppressed. This unusual
1077 -- situation requires a predicate of its own.
1079 ----------------------------------------
1080 -- Is_Aliased_Unconstrained_Component --
1081 ----------------------------------------
1083 function Is_Aliased_Unconstrained_Component return Boolean is
1088 if Nkind (Lhs) /= N_Selected_Component then
1091 Comp := Entity (Selector_Name (Lhs));
1092 Pref := Prefix (Lhs);
1095 if Ekind (Comp) /= E_Component
1096 or else not Is_Aliased (Comp)
1101 return not Comes_From_Source (Pref)
1102 and then In_Instance
1103 and then not Is_Constrained (Etype (Comp));
1104 end Is_Aliased_Unconstrained_Component;
1106 -- Start of processing for Apply_Discriminant_Check
1110 T_Typ := Designated_Type (Typ);
1115 -- Nothing to do if discriminant checks are suppressed or else no code
1116 -- is to be generated
1118 if not Expander_Active
1119 or else Discriminant_Checks_Suppressed (T_Typ)
1124 -- No discriminant checks necessary for an access when expression is
1125 -- statically Null. This is not only an optimization, it is fundamental
1126 -- because otherwise discriminant checks may be generated in init procs
1127 -- for types containing an access to a not-yet-frozen record, causing a
1128 -- deadly forward reference.
1130 -- Also, if the expression is of an access type whose designated type is
1131 -- incomplete, then the access value must be null and we suppress the
1134 if Known_Null (N) then
1137 elsif Is_Access_Type (S_Typ) then
1138 S_Typ := Designated_Type (S_Typ);
1140 if Ekind (S_Typ) = E_Incomplete_Type then
1145 -- If an assignment target is present, then we need to generate the
1146 -- actual subtype if the target is a parameter or aliased object with
1147 -- an unconstrained nominal subtype.
1149 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1150 -- subtype to the parameter and dereference cases, since other aliased
1151 -- objects are unconstrained (unless the nominal subtype is explicitly
1152 -- constrained). (But we also need to test for renamings???)
1155 and then (Present (Param_Entity (Lhs))
1156 or else (Ada_Version < Ada_05
1157 and then not Is_Constrained (T_Typ)
1158 and then Is_Aliased_View (Lhs)
1159 and then not Is_Aliased_Unconstrained_Component)
1160 or else (Ada_Version >= Ada_05
1161 and then not Is_Constrained (T_Typ)
1162 and then Nkind (Lhs) = N_Explicit_Dereference
1163 and then Nkind (Original_Node (Lhs)) /=
1166 T_Typ := Get_Actual_Subtype (Lhs);
1169 -- Nothing to do if the type is unconstrained (this is the case where
1170 -- the actual subtype in the RM sense of N is unconstrained and no check
1173 if not Is_Constrained (T_Typ) then
1176 -- Ada 2005: nothing to do if the type is one for which there is a
1177 -- partial view that is constrained.
1179 elsif Ada_Version >= Ada_05
1180 and then Has_Constrained_Partial_View (Base_Type (T_Typ))
1185 -- Nothing to do if the type is an Unchecked_Union
1187 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1191 -- Suppress checks if the subtypes are the same. the check must be
1192 -- preserved in an assignment to a formal, because the constraint is
1193 -- given by the actual.
1195 if Nkind (Original_Node (N)) /= N_Allocator
1197 or else not Is_Entity_Name (Lhs)
1198 or else No (Param_Entity (Lhs)))
1201 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1202 and then not Is_Aliased_View (Lhs)
1207 -- We can also eliminate checks on allocators with a subtype mark that
1208 -- coincides with the context type. The context type may be a subtype
1209 -- without a constraint (common case, a generic actual).
1211 elsif Nkind (Original_Node (N)) = N_Allocator
1212 and then Is_Entity_Name (Expression (Original_Node (N)))
1215 Alloc_Typ : constant Entity_Id :=
1216 Entity (Expression (Original_Node (N)));
1219 if Alloc_Typ = T_Typ
1220 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1221 and then Is_Entity_Name (
1222 Subtype_Indication (Parent (T_Typ)))
1223 and then Alloc_Typ = Base_Type (T_Typ))
1231 -- See if we have a case where the types are both constrained, and all
1232 -- the constraints are constants. In this case, we can do the check
1233 -- successfully at compile time.
1235 -- We skip this check for the case where the node is a rewritten`
1236 -- allocator, because it already carries the context subtype, and
1237 -- extracting the discriminants from the aggregate is messy.
1239 if Is_Constrained (S_Typ)
1240 and then Nkind (Original_Node (N)) /= N_Allocator
1250 -- S_Typ may not have discriminants in the case where it is a
1251 -- private type completed by a default discriminated type. In that
1252 -- case, we need to get the constraints from the underlying_type.
1253 -- If the underlying type is unconstrained (i.e. has no default
1254 -- discriminants) no check is needed.
1256 if Has_Discriminants (S_Typ) then
1257 Discr := First_Discriminant (S_Typ);
1258 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1261 Discr := First_Discriminant (Underlying_Type (S_Typ));
1264 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1270 -- A further optimization: if T_Typ is derived from S_Typ
1271 -- without imposing a constraint, no check is needed.
1273 if Nkind (Original_Node (Parent (T_Typ))) =
1274 N_Full_Type_Declaration
1277 Type_Def : constant Node_Id :=
1279 (Original_Node (Parent (T_Typ)));
1281 if Nkind (Type_Def) = N_Derived_Type_Definition
1282 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1283 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1291 DconT := First_Elmt (Discriminant_Constraint (T_Typ));
1293 while Present (Discr) loop
1294 ItemS := Node (DconS);
1295 ItemT := Node (DconT);
1297 -- For a discriminated component type constrained by the
1298 -- current instance of an enclosing type, there is no
1299 -- applicable discriminant check.
1301 if Nkind (ItemT) = N_Attribute_Reference
1302 and then Is_Access_Type (Etype (ItemT))
1303 and then Is_Entity_Name (Prefix (ItemT))
1304 and then Is_Type (Entity (Prefix (ItemT)))
1309 -- If the expressions for the discriminants are identical
1310 -- and it is side-effect free (for now just an entity),
1311 -- this may be a shared constraint, e.g. from a subtype
1312 -- without a constraint introduced as a generic actual.
1313 -- Examine other discriminants if any.
1316 and then Is_Entity_Name (ItemS)
1320 elsif not Is_OK_Static_Expression (ItemS)
1321 or else not Is_OK_Static_Expression (ItemT)
1325 elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
1326 if Do_Access then -- needs run-time check.
1329 Apply_Compile_Time_Constraint_Error
1330 (N, "incorrect value for discriminant&?",
1331 CE_Discriminant_Check_Failed, Ent => Discr);
1338 Next_Discriminant (Discr);
1347 -- Here we need a discriminant check. First build the expression
1348 -- for the comparisons of the discriminants:
1350 -- (n.disc1 /= typ.disc1) or else
1351 -- (n.disc2 /= typ.disc2) or else
1353 -- (n.discn /= typ.discn)
1355 Cond := Build_Discriminant_Checks (N, T_Typ);
1357 -- If Lhs is set and is a parameter, then the condition is
1358 -- guarded by: lhs'constrained and then (condition built above)
1360 if Present (Param_Entity (Lhs)) then
1364 Make_Attribute_Reference (Loc,
1365 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1366 Attribute_Name => Name_Constrained),
1367 Right_Opnd => Cond);
1371 Cond := Guard_Access (Cond, Loc, N);
1375 Make_Raise_Constraint_Error (Loc,
1377 Reason => CE_Discriminant_Check_Failed));
1378 end Apply_Discriminant_Check;
1380 ------------------------
1381 -- Apply_Divide_Check --
1382 ------------------------
1384 procedure Apply_Divide_Check (N : Node_Id) is
1385 Loc : constant Source_Ptr := Sloc (N);
1386 Typ : constant Entity_Id := Etype (N);
1387 Left : constant Node_Id := Left_Opnd (N);
1388 Right : constant Node_Id := Right_Opnd (N);
1398 pragma Warnings (Off, Lhi);
1399 -- Don't actually use this value
1403 and then not Backend_Divide_Checks_On_Target
1404 and then Check_Needed (Right, Division_Check)
1406 Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True);
1408 -- See if division by zero possible, and if so generate test. This
1409 -- part of the test is not controlled by the -gnato switch.
1411 if Do_Division_Check (N) then
1412 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1414 Make_Raise_Constraint_Error (Loc,
1417 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1418 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1419 Reason => CE_Divide_By_Zero));
1423 -- Test for extremely annoying case of xxx'First divided by -1
1425 if Do_Overflow_Check (N) then
1426 if Nkind (N) = N_Op_Divide
1427 and then Is_Signed_Integer_Type (Typ)
1429 Determine_Range (Left, LOK, Llo, Lhi, Assume_Valid => True);
1430 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1432 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1434 ((not LOK) or else (Llo = LLB))
1437 Make_Raise_Constraint_Error (Loc,
1443 Duplicate_Subexpr_Move_Checks (Left),
1444 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1448 Duplicate_Subexpr (Right),
1450 Make_Integer_Literal (Loc, -1))),
1451 Reason => CE_Overflow_Check_Failed));
1456 end Apply_Divide_Check;
1458 ----------------------------------
1459 -- Apply_Float_Conversion_Check --
1460 ----------------------------------
1462 -- Let F and I be the source and target types of the conversion. The RM
1463 -- specifies that a floating-point value X is rounded to the nearest
1464 -- integer, with halfway cases being rounded away from zero. The rounded
1465 -- value of X is checked against I'Range.
1467 -- The catch in the above paragraph is that there is no good way to know
1468 -- whether the round-to-integer operation resulted in overflow. A remedy is
1469 -- to perform a range check in the floating-point domain instead, however:
1471 -- (1) The bounds may not be known at compile time
1472 -- (2) The check must take into account rounding or truncation.
1473 -- (3) The range of type I may not be exactly representable in F.
1474 -- (4) For the rounding case, The end-points I'First - 0.5 and
1475 -- I'Last + 0.5 may or may not be in range, depending on the
1476 -- sign of I'First and I'Last.
1477 -- (5) X may be a NaN, which will fail any comparison
1479 -- The following steps correctly convert X with rounding:
1481 -- (1) If either I'First or I'Last is not known at compile time, use
1482 -- I'Base instead of I in the next three steps and perform a
1483 -- regular range check against I'Range after conversion.
1484 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1485 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1486 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1487 -- In other words, take one of the closest floating-point numbers
1488 -- (which is an integer value) to I'First, and see if it is in
1490 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1491 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1492 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1493 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1494 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1496 -- For the truncating case, replace steps (2) and (3) as follows:
1497 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1498 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1500 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1501 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1504 procedure Apply_Float_Conversion_Check
1506 Target_Typ : Entity_Id)
1508 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1509 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1510 Loc : constant Source_Ptr := Sloc (Ck_Node);
1511 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1512 Target_Base : constant Entity_Id :=
1513 Implementation_Base_Type (Target_Typ);
1515 Par : constant Node_Id := Parent (Ck_Node);
1516 pragma Assert (Nkind (Par) = N_Type_Conversion);
1517 -- Parent of check node, must be a type conversion
1519 Truncate : constant Boolean := Float_Truncate (Par);
1520 Max_Bound : constant Uint :=
1522 (Machine_Radix (Expr_Type),
1523 Machine_Mantissa (Expr_Type) - 1) - 1;
1525 -- Largest bound, so bound plus or minus half is a machine number of F
1527 Ifirst, Ilast : Uint;
1528 -- Bounds of integer type
1531 -- Bounds to check in floating-point domain
1533 Lo_OK, Hi_OK : Boolean;
1534 -- True iff Lo resp. Hi belongs to I'Range
1536 Lo_Chk, Hi_Chk : Node_Id;
1537 -- Expressions that are False iff check fails
1539 Reason : RT_Exception_Code;
1542 if not Compile_Time_Known_Value (LB)
1543 or not Compile_Time_Known_Value (HB)
1546 -- First check that the value falls in the range of the base type,
1547 -- to prevent overflow during conversion and then perform a
1548 -- regular range check against the (dynamic) bounds.
1550 pragma Assert (Target_Base /= Target_Typ);
1552 Temp : constant Entity_Id :=
1553 Make_Defining_Identifier (Loc,
1554 Chars => New_Internal_Name ('T'));
1557 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1558 Set_Etype (Temp, Target_Base);
1560 Insert_Action (Parent (Par),
1561 Make_Object_Declaration (Loc,
1562 Defining_Identifier => Temp,
1563 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1564 Expression => New_Copy_Tree (Par)),
1565 Suppress => All_Checks);
1568 Make_Raise_Constraint_Error (Loc,
1571 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1572 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1573 Reason => CE_Range_Check_Failed));
1574 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
1580 -- Get the (static) bounds of the target type
1582 Ifirst := Expr_Value (LB);
1583 Ilast := Expr_Value (HB);
1585 -- A simple optimization: if the expression is a universal literal,
1586 -- we can do the comparison with the bounds and the conversion to
1587 -- an integer type statically. The range checks are unchanged.
1589 if Nkind (Ck_Node) = N_Real_Literal
1590 and then Etype (Ck_Node) = Universal_Real
1591 and then Is_Integer_Type (Target_Typ)
1592 and then Nkind (Parent (Ck_Node)) = N_Type_Conversion
1595 Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node));
1598 if Int_Val <= Ilast and then Int_Val >= Ifirst then
1600 -- Conversion is safe
1602 Rewrite (Parent (Ck_Node),
1603 Make_Integer_Literal (Loc, UI_To_Int (Int_Val)));
1604 Analyze_And_Resolve (Parent (Ck_Node), Target_Typ);
1610 -- Check against lower bound
1612 if Truncate and then Ifirst > 0 then
1613 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
1617 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
1620 elsif abs (Ifirst) < Max_Bound then
1621 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
1622 Lo_OK := (Ifirst > 0);
1625 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
1626 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
1631 -- Lo_Chk := (X >= Lo)
1633 Lo_Chk := Make_Op_Ge (Loc,
1634 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1635 Right_Opnd => Make_Real_Literal (Loc, Lo));
1638 -- Lo_Chk := (X > Lo)
1640 Lo_Chk := Make_Op_Gt (Loc,
1641 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1642 Right_Opnd => Make_Real_Literal (Loc, Lo));
1645 -- Check against higher bound
1647 if Truncate and then Ilast < 0 then
1648 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
1652 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
1655 elsif abs (Ilast) < Max_Bound then
1656 Hi := UR_From_Uint (Ilast) + Ureal_Half;
1657 Hi_OK := (Ilast < 0);
1659 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
1660 Hi_OK := (Hi <= UR_From_Uint (Ilast));
1665 -- Hi_Chk := (X <= Hi)
1667 Hi_Chk := Make_Op_Le (Loc,
1668 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1669 Right_Opnd => Make_Real_Literal (Loc, Hi));
1672 -- Hi_Chk := (X < Hi)
1674 Hi_Chk := Make_Op_Lt (Loc,
1675 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1676 Right_Opnd => Make_Real_Literal (Loc, Hi));
1679 -- If the bounds of the target type are the same as those of the base
1680 -- type, the check is an overflow check as a range check is not
1681 -- performed in these cases.
1683 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
1684 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
1686 Reason := CE_Overflow_Check_Failed;
1688 Reason := CE_Range_Check_Failed;
1691 -- Raise CE if either conditions does not hold
1693 Insert_Action (Ck_Node,
1694 Make_Raise_Constraint_Error (Loc,
1695 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
1697 end Apply_Float_Conversion_Check;
1699 ------------------------
1700 -- Apply_Length_Check --
1701 ------------------------
1703 procedure Apply_Length_Check
1705 Target_Typ : Entity_Id;
1706 Source_Typ : Entity_Id := Empty)
1709 Apply_Selected_Length_Checks
1710 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1711 end Apply_Length_Check;
1713 -----------------------
1714 -- Apply_Range_Check --
1715 -----------------------
1717 procedure Apply_Range_Check
1719 Target_Typ : Entity_Id;
1720 Source_Typ : Entity_Id := Empty)
1723 Apply_Selected_Range_Checks
1724 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1725 end Apply_Range_Check;
1727 ------------------------------
1728 -- Apply_Scalar_Range_Check --
1729 ------------------------------
1731 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
1732 -- off if it is already set on.
1734 procedure Apply_Scalar_Range_Check
1736 Target_Typ : Entity_Id;
1737 Source_Typ : Entity_Id := Empty;
1738 Fixed_Int : Boolean := False)
1740 Parnt : constant Node_Id := Parent (Expr);
1742 Arr : Node_Id := Empty; -- initialize to prevent warning
1743 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
1746 Is_Subscr_Ref : Boolean;
1747 -- Set true if Expr is a subscript
1749 Is_Unconstrained_Subscr_Ref : Boolean;
1750 -- Set true if Expr is a subscript of an unconstrained array. In this
1751 -- case we do not attempt to do an analysis of the value against the
1752 -- range of the subscript, since we don't know the actual subtype.
1755 -- Set to True if Expr should be regarded as a real value even though
1756 -- the type of Expr might be discrete.
1758 procedure Bad_Value;
1759 -- Procedure called if value is determined to be out of range
1765 procedure Bad_Value is
1767 Apply_Compile_Time_Constraint_Error
1768 (Expr, "value not in range of}?", CE_Range_Check_Failed,
1773 -- Start of processing for Apply_Scalar_Range_Check
1776 -- Return if check obviously not needed
1779 -- Not needed inside generic
1783 -- Not needed if previous error
1785 or else Target_Typ = Any_Type
1786 or else Nkind (Expr) = N_Error
1788 -- Not needed for non-scalar type
1790 or else not Is_Scalar_Type (Target_Typ)
1792 -- Not needed if we know node raises CE already
1794 or else Raises_Constraint_Error (Expr)
1799 -- Now, see if checks are suppressed
1802 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
1804 if Is_Subscr_Ref then
1805 Arr := Prefix (Parnt);
1806 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
1809 if not Do_Range_Check (Expr) then
1811 -- Subscript reference. Check for Index_Checks suppressed
1813 if Is_Subscr_Ref then
1815 -- Check array type and its base type
1817 if Index_Checks_Suppressed (Arr_Typ)
1818 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
1822 -- Check array itself if it is an entity name
1824 elsif Is_Entity_Name (Arr)
1825 and then Index_Checks_Suppressed (Entity (Arr))
1829 -- Check expression itself if it is an entity name
1831 elsif Is_Entity_Name (Expr)
1832 and then Index_Checks_Suppressed (Entity (Expr))
1837 -- All other cases, check for Range_Checks suppressed
1840 -- Check target type and its base type
1842 if Range_Checks_Suppressed (Target_Typ)
1843 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
1847 -- Check expression itself if it is an entity name
1849 elsif Is_Entity_Name (Expr)
1850 and then Range_Checks_Suppressed (Entity (Expr))
1854 -- If Expr is part of an assignment statement, then check left
1855 -- side of assignment if it is an entity name.
1857 elsif Nkind (Parnt) = N_Assignment_Statement
1858 and then Is_Entity_Name (Name (Parnt))
1859 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
1866 -- Do not set range checks if they are killed
1868 if Nkind (Expr) = N_Unchecked_Type_Conversion
1869 and then Kill_Range_Check (Expr)
1874 -- Do not set range checks for any values from System.Scalar_Values
1875 -- since the whole idea of such values is to avoid checking them!
1877 if Is_Entity_Name (Expr)
1878 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
1883 -- Now see if we need a check
1885 if No (Source_Typ) then
1886 S_Typ := Etype (Expr);
1888 S_Typ := Source_Typ;
1891 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
1895 Is_Unconstrained_Subscr_Ref :=
1896 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
1898 -- Always do a range check if the source type includes infinities and
1899 -- the target type does not include infinities. We do not do this if
1900 -- range checks are killed.
1902 if Is_Floating_Point_Type (S_Typ)
1903 and then Has_Infinities (S_Typ)
1904 and then not Has_Infinities (Target_Typ)
1906 Enable_Range_Check (Expr);
1909 -- Return if we know expression is definitely in the range of the target
1910 -- type as determined by Determine_Range. Right now we only do this for
1911 -- discrete types, and not fixed-point or floating-point types.
1913 -- The additional less-precise tests below catch these cases
1915 -- Note: skip this if we are given a source_typ, since the point of
1916 -- supplying a Source_Typ is to stop us looking at the expression.
1917 -- We could sharpen this test to be out parameters only ???
1919 if Is_Discrete_Type (Target_Typ)
1920 and then Is_Discrete_Type (Etype (Expr))
1921 and then not Is_Unconstrained_Subscr_Ref
1922 and then No (Source_Typ)
1925 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
1926 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
1931 if Compile_Time_Known_Value (Tlo)
1932 and then Compile_Time_Known_Value (Thi)
1935 Lov : constant Uint := Expr_Value (Tlo);
1936 Hiv : constant Uint := Expr_Value (Thi);
1939 -- If range is null, we for sure have a constraint error
1940 -- (we don't even need to look at the value involved,
1941 -- since all possible values will raise CE).
1948 -- Otherwise determine range of value
1950 Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True);
1954 -- If definitely in range, all OK
1956 if Lo >= Lov and then Hi <= Hiv then
1959 -- If definitely not in range, warn
1961 elsif Lov > Hi or else Hiv < Lo then
1965 -- Otherwise we don't know
1977 Is_Floating_Point_Type (S_Typ)
1978 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
1980 -- Check if we can determine at compile time whether Expr is in the
1981 -- range of the target type. Note that if S_Typ is within the bounds
1982 -- of Target_Typ then this must be the case. This check is meaningful
1983 -- only if this is not a conversion between integer and real types.
1985 if not Is_Unconstrained_Subscr_Ref
1987 Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
1989 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
1991 Is_In_Range (Expr, Target_Typ,
1992 Assume_Valid => True,
1993 Fixed_Int => Fixed_Int,
1994 Int_Real => Int_Real))
1998 elsif Is_Out_Of_Range (Expr, Target_Typ,
1999 Assume_Valid => True,
2000 Fixed_Int => Fixed_Int,
2001 Int_Real => Int_Real)
2006 -- In the floating-point case, we only do range checks if the type is
2007 -- constrained. We definitely do NOT want range checks for unconstrained
2008 -- types, since we want to have infinities
2010 elsif Is_Floating_Point_Type (S_Typ) then
2011 if Is_Constrained (S_Typ) then
2012 Enable_Range_Check (Expr);
2015 -- For all other cases we enable a range check unconditionally
2018 Enable_Range_Check (Expr);
2021 end Apply_Scalar_Range_Check;
2023 ----------------------------------
2024 -- Apply_Selected_Length_Checks --
2025 ----------------------------------
2027 procedure Apply_Selected_Length_Checks
2029 Target_Typ : Entity_Id;
2030 Source_Typ : Entity_Id;
2031 Do_Static : Boolean)
2034 R_Result : Check_Result;
2037 Loc : constant Source_Ptr := Sloc (Ck_Node);
2038 Checks_On : constant Boolean :=
2039 (not Index_Checks_Suppressed (Target_Typ))
2041 (not Length_Checks_Suppressed (Target_Typ));
2044 if not Expander_Active then
2049 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2051 for J in 1 .. 2 loop
2052 R_Cno := R_Result (J);
2053 exit when No (R_Cno);
2055 -- A length check may mention an Itype which is attached to a
2056 -- subsequent node. At the top level in a package this can cause
2057 -- an order-of-elaboration problem, so we make sure that the itype
2058 -- is referenced now.
2060 if Ekind (Current_Scope) = E_Package
2061 and then Is_Compilation_Unit (Current_Scope)
2063 Ensure_Defined (Target_Typ, Ck_Node);
2065 if Present (Source_Typ) then
2066 Ensure_Defined (Source_Typ, Ck_Node);
2068 elsif Is_Itype (Etype (Ck_Node)) then
2069 Ensure_Defined (Etype (Ck_Node), Ck_Node);
2073 -- If the item is a conditional raise of constraint error, then have
2074 -- a look at what check is being performed and ???
2076 if Nkind (R_Cno) = N_Raise_Constraint_Error
2077 and then Present (Condition (R_Cno))
2079 Cond := Condition (R_Cno);
2081 -- Case where node does not now have a dynamic check
2083 if not Has_Dynamic_Length_Check (Ck_Node) then
2085 -- If checks are on, just insert the check
2088 Insert_Action (Ck_Node, R_Cno);
2090 if not Do_Static then
2091 Set_Has_Dynamic_Length_Check (Ck_Node);
2094 -- If checks are off, then analyze the length check after
2095 -- temporarily attaching it to the tree in case the relevant
2096 -- condition can be evaluted at compile time. We still want a
2097 -- compile time warning in this case.
2100 Set_Parent (R_Cno, Ck_Node);
2105 -- Output a warning if the condition is known to be True
2107 if Is_Entity_Name (Cond)
2108 and then Entity (Cond) = Standard_True
2110 Apply_Compile_Time_Constraint_Error
2111 (Ck_Node, "wrong length for array of}?",
2112 CE_Length_Check_Failed,
2116 -- If we were only doing a static check, or if checks are not
2117 -- on, then we want to delete the check, since it is not needed.
2118 -- We do this by replacing the if statement by a null statement
2120 elsif Do_Static or else not Checks_On then
2121 Remove_Warning_Messages (R_Cno);
2122 Rewrite (R_Cno, Make_Null_Statement (Loc));
2126 Install_Static_Check (R_Cno, Loc);
2129 end Apply_Selected_Length_Checks;
2131 ---------------------------------
2132 -- Apply_Selected_Range_Checks --
2133 ---------------------------------
2135 procedure Apply_Selected_Range_Checks
2137 Target_Typ : Entity_Id;
2138 Source_Typ : Entity_Id;
2139 Do_Static : Boolean)
2142 R_Result : Check_Result;
2145 Loc : constant Source_Ptr := Sloc (Ck_Node);
2146 Checks_On : constant Boolean :=
2147 (not Index_Checks_Suppressed (Target_Typ))
2149 (not Range_Checks_Suppressed (Target_Typ));
2152 if not Expander_Active or else not Checks_On then
2157 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2159 for J in 1 .. 2 loop
2161 R_Cno := R_Result (J);
2162 exit when No (R_Cno);
2164 -- If the item is a conditional raise of constraint error, then have
2165 -- a look at what check is being performed and ???
2167 if Nkind (R_Cno) = N_Raise_Constraint_Error
2168 and then Present (Condition (R_Cno))
2170 Cond := Condition (R_Cno);
2172 if not Has_Dynamic_Range_Check (Ck_Node) then
2173 Insert_Action (Ck_Node, R_Cno);
2175 if not Do_Static then
2176 Set_Has_Dynamic_Range_Check (Ck_Node);
2180 -- Output a warning if the condition is known to be True
2182 if Is_Entity_Name (Cond)
2183 and then Entity (Cond) = Standard_True
2185 -- Since an N_Range is technically not an expression, we have
2186 -- to set one of the bounds to C_E and then just flag the
2187 -- N_Range. The warning message will point to the lower bound
2188 -- and complain about a range, which seems OK.
2190 if Nkind (Ck_Node) = N_Range then
2191 Apply_Compile_Time_Constraint_Error
2192 (Low_Bound (Ck_Node), "static range out of bounds of}?",
2193 CE_Range_Check_Failed,
2197 Set_Raises_Constraint_Error (Ck_Node);
2200 Apply_Compile_Time_Constraint_Error
2201 (Ck_Node, "static value out of range of}?",
2202 CE_Range_Check_Failed,
2207 -- If we were only doing a static check, or if checks are not
2208 -- on, then we want to delete the check, since it is not needed.
2209 -- We do this by replacing the if statement by a null statement
2211 elsif Do_Static or else not Checks_On then
2212 Remove_Warning_Messages (R_Cno);
2213 Rewrite (R_Cno, Make_Null_Statement (Loc));
2217 Install_Static_Check (R_Cno, Loc);
2220 end Apply_Selected_Range_Checks;
2222 -------------------------------
2223 -- Apply_Static_Length_Check --
2224 -------------------------------
2226 procedure Apply_Static_Length_Check
2228 Target_Typ : Entity_Id;
2229 Source_Typ : Entity_Id := Empty)
2232 Apply_Selected_Length_Checks
2233 (Expr, Target_Typ, Source_Typ, Do_Static => True);
2234 end Apply_Static_Length_Check;
2236 -------------------------------------
2237 -- Apply_Subscript_Validity_Checks --
2238 -------------------------------------
2240 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
2244 pragma Assert (Nkind (Expr) = N_Indexed_Component);
2246 -- Loop through subscripts
2248 Sub := First (Expressions (Expr));
2249 while Present (Sub) loop
2251 -- Check one subscript. Note that we do not worry about enumeration
2252 -- type with holes, since we will convert the value to a Pos value
2253 -- for the subscript, and that convert will do the necessary validity
2256 Ensure_Valid (Sub, Holes_OK => True);
2258 -- Move to next subscript
2262 end Apply_Subscript_Validity_Checks;
2264 ----------------------------------
2265 -- Apply_Type_Conversion_Checks --
2266 ----------------------------------
2268 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
2269 Target_Type : constant Entity_Id := Etype (N);
2270 Target_Base : constant Entity_Id := Base_Type (Target_Type);
2271 Expr : constant Node_Id := Expression (N);
2272 Expr_Type : constant Entity_Id := Etype (Expr);
2275 if Inside_A_Generic then
2278 -- Skip these checks if serious errors detected, there are some nasty
2279 -- situations of incomplete trees that blow things up.
2281 elsif Serious_Errors_Detected > 0 then
2284 -- Scalar type conversions of the form Target_Type (Expr) require a
2285 -- range check if we cannot be sure that Expr is in the base type of
2286 -- Target_Typ and also that Expr is in the range of Target_Typ. These
2287 -- are not quite the same condition from an implementation point of
2288 -- view, but clearly the second includes the first.
2290 elsif Is_Scalar_Type (Target_Type) then
2292 Conv_OK : constant Boolean := Conversion_OK (N);
2293 -- If the Conversion_OK flag on the type conversion is set and no
2294 -- floating point type is involved in the type conversion then
2295 -- fixed point values must be read as integral values.
2297 Float_To_Int : constant Boolean :=
2298 Is_Floating_Point_Type (Expr_Type)
2299 and then Is_Integer_Type (Target_Type);
2302 if not Overflow_Checks_Suppressed (Target_Base)
2304 In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK)
2305 and then not Float_To_Int
2307 Activate_Overflow_Check (N);
2310 if not Range_Checks_Suppressed (Target_Type)
2311 and then not Range_Checks_Suppressed (Expr_Type)
2313 if Float_To_Int then
2314 Apply_Float_Conversion_Check (Expr, Target_Type);
2316 Apply_Scalar_Range_Check
2317 (Expr, Target_Type, Fixed_Int => Conv_OK);
2322 elsif Comes_From_Source (N)
2323 and then not Discriminant_Checks_Suppressed (Target_Type)
2324 and then Is_Record_Type (Target_Type)
2325 and then Is_Derived_Type (Target_Type)
2326 and then not Is_Tagged_Type (Target_Type)
2327 and then not Is_Constrained (Target_Type)
2328 and then Present (Stored_Constraint (Target_Type))
2330 -- An unconstrained derived type may have inherited discriminant
2331 -- Build an actual discriminant constraint list using the stored
2332 -- constraint, to verify that the expression of the parent type
2333 -- satisfies the constraints imposed by the (unconstrained!)
2334 -- derived type. This applies to value conversions, not to view
2335 -- conversions of tagged types.
2338 Loc : constant Source_Ptr := Sloc (N);
2340 Constraint : Elmt_Id;
2341 Discr_Value : Node_Id;
2344 New_Constraints : constant Elist_Id := New_Elmt_List;
2345 Old_Constraints : constant Elist_Id :=
2346 Discriminant_Constraint (Expr_Type);
2349 Constraint := First_Elmt (Stored_Constraint (Target_Type));
2350 while Present (Constraint) loop
2351 Discr_Value := Node (Constraint);
2353 if Is_Entity_Name (Discr_Value)
2354 and then Ekind (Entity (Discr_Value)) = E_Discriminant
2356 Discr := Corresponding_Discriminant (Entity (Discr_Value));
2359 and then Scope (Discr) = Base_Type (Expr_Type)
2361 -- Parent is constrained by new discriminant. Obtain
2362 -- Value of original discriminant in expression. If the
2363 -- new discriminant has been used to constrain more than
2364 -- one of the stored discriminants, this will provide the
2365 -- required consistency check.
2368 Make_Selected_Component (Loc,
2370 Duplicate_Subexpr_No_Checks
2371 (Expr, Name_Req => True),
2373 Make_Identifier (Loc, Chars (Discr))),
2377 -- Discriminant of more remote ancestor ???
2382 -- Derived type definition has an explicit value for this
2383 -- stored discriminant.
2387 (Duplicate_Subexpr_No_Checks (Discr_Value),
2391 Next_Elmt (Constraint);
2394 -- Use the unconstrained expression type to retrieve the
2395 -- discriminants of the parent, and apply momentarily the
2396 -- discriminant constraint synthesized above.
2398 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
2399 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
2400 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
2403 Make_Raise_Constraint_Error (Loc,
2405 Reason => CE_Discriminant_Check_Failed));
2408 -- For arrays, conversions are applied during expansion, to take into
2409 -- accounts changes of representation. The checks become range checks on
2410 -- the base type or length checks on the subtype, depending on whether
2411 -- the target type is unconstrained or constrained.
2416 end Apply_Type_Conversion_Checks;
2418 ----------------------------------------------
2419 -- Apply_Universal_Integer_Attribute_Checks --
2420 ----------------------------------------------
2422 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
2423 Loc : constant Source_Ptr := Sloc (N);
2424 Typ : constant Entity_Id := Etype (N);
2427 if Inside_A_Generic then
2430 -- Nothing to do if checks are suppressed
2432 elsif Range_Checks_Suppressed (Typ)
2433 and then Overflow_Checks_Suppressed (Typ)
2437 -- Nothing to do if the attribute does not come from source. The
2438 -- internal attributes we generate of this type do not need checks,
2439 -- and furthermore the attempt to check them causes some circular
2440 -- elaboration orders when dealing with packed types.
2442 elsif not Comes_From_Source (N) then
2445 -- If the prefix is a selected component that depends on a discriminant
2446 -- the check may improperly expose a discriminant instead of using
2447 -- the bounds of the object itself. Set the type of the attribute to
2448 -- the base type of the context, so that a check will be imposed when
2449 -- needed (e.g. if the node appears as an index).
2451 elsif Nkind (Prefix (N)) = N_Selected_Component
2452 and then Ekind (Typ) = E_Signed_Integer_Subtype
2453 and then Depends_On_Discriminant (Scalar_Range (Typ))
2455 Set_Etype (N, Base_Type (Typ));
2457 -- Otherwise, replace the attribute node with a type conversion node
2458 -- whose expression is the attribute, retyped to universal integer, and
2459 -- whose subtype mark is the target type. The call to analyze this
2460 -- conversion will set range and overflow checks as required for proper
2461 -- detection of an out of range value.
2464 Set_Etype (N, Universal_Integer);
2465 Set_Analyzed (N, True);
2468 Make_Type_Conversion (Loc,
2469 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
2470 Expression => Relocate_Node (N)));
2472 Analyze_And_Resolve (N, Typ);
2475 end Apply_Universal_Integer_Attribute_Checks;
2477 -------------------------------
2478 -- Build_Discriminant_Checks --
2479 -------------------------------
2481 function Build_Discriminant_Checks
2483 T_Typ : Entity_Id) return Node_Id
2485 Loc : constant Source_Ptr := Sloc (N);
2488 Disc_Ent : Entity_Id;
2492 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
2494 ----------------------------------
2495 -- Aggregate_Discriminant_Value --
2496 ----------------------------------
2498 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
2502 -- The aggregate has been normalized with named associations. We use
2503 -- the Chars field to locate the discriminant to take into account
2504 -- discriminants in derived types, which carry the same name as those
2507 Assoc := First (Component_Associations (N));
2508 while Present (Assoc) loop
2509 if Chars (First (Choices (Assoc))) = Chars (Disc) then
2510 return Expression (Assoc);
2516 -- Discriminant must have been found in the loop above
2518 raise Program_Error;
2519 end Aggregate_Discriminant_Val;
2521 -- Start of processing for Build_Discriminant_Checks
2524 -- Loop through discriminants evolving the condition
2527 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
2529 -- For a fully private type, use the discriminants of the parent type
2531 if Is_Private_Type (T_Typ)
2532 and then No (Full_View (T_Typ))
2534 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
2536 Disc_Ent := First_Discriminant (T_Typ);
2539 while Present (Disc) loop
2540 Dval := Node (Disc);
2542 if Nkind (Dval) = N_Identifier
2543 and then Ekind (Entity (Dval)) = E_Discriminant
2545 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
2547 Dval := Duplicate_Subexpr_No_Checks (Dval);
2550 -- If we have an Unchecked_Union node, we can infer the discriminants
2553 if Is_Unchecked_Union (Base_Type (T_Typ)) then
2555 Get_Discriminant_Value (
2556 First_Discriminant (T_Typ),
2558 Stored_Constraint (T_Typ)));
2560 elsif Nkind (N) = N_Aggregate then
2562 Duplicate_Subexpr_No_Checks
2563 (Aggregate_Discriminant_Val (Disc_Ent));
2567 Make_Selected_Component (Loc,
2569 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
2571 Make_Identifier (Loc, Chars (Disc_Ent)));
2573 Set_Is_In_Discriminant_Check (Dref);
2576 Evolve_Or_Else (Cond,
2579 Right_Opnd => Dval));
2582 Next_Discriminant (Disc_Ent);
2586 end Build_Discriminant_Checks;
2592 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
2600 -- Always check if not simple entity
2602 if Nkind (Nod) not in N_Has_Entity
2603 or else not Comes_From_Source (Nod)
2608 -- Look up tree for short circuit
2615 -- Done if out of subexpression (note that we allow generated stuff
2616 -- such as itype declarations in this context, to keep the loop going
2617 -- since we may well have generated such stuff in complex situations.
2618 -- Also done if no parent (probably an error condition, but no point
2619 -- in behaving nasty if we find it!)
2622 or else (K not in N_Subexpr and then Comes_From_Source (P))
2626 -- Or/Or Else case, where test is part of the right operand, or is
2627 -- part of one of the actions associated with the right operand, and
2628 -- the left operand is an equality test.
2630 elsif K = N_Op_Or then
2631 exit when N = Right_Opnd (P)
2632 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2634 elsif K = N_Or_Else then
2635 exit when (N = Right_Opnd (P)
2638 and then List_Containing (N) = Actions (P)))
2639 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2641 -- Similar test for the And/And then case, where the left operand
2642 -- is an inequality test.
2644 elsif K = N_Op_And then
2645 exit when N = Right_Opnd (P)
2646 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2648 elsif K = N_And_Then then
2649 exit when (N = Right_Opnd (P)
2652 and then List_Containing (N) = Actions (P)))
2653 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2659 -- If we fall through the loop, then we have a conditional with an
2660 -- appropriate test as its left operand. So test further.
2663 R := Right_Opnd (L);
2666 -- Left operand of test must match original variable
2668 if Nkind (L) not in N_Has_Entity
2669 or else Entity (L) /= Entity (Nod)
2674 -- Right operand of test must be key value (zero or null)
2677 when Access_Check =>
2678 if not Known_Null (R) then
2682 when Division_Check =>
2683 if not Compile_Time_Known_Value (R)
2684 or else Expr_Value (R) /= Uint_0
2690 raise Program_Error;
2693 -- Here we have the optimizable case, warn if not short-circuited
2695 if K = N_Op_And or else K = N_Op_Or then
2697 when Access_Check =>
2699 ("Constraint_Error may be raised (access check)?",
2701 when Division_Check =>
2703 ("Constraint_Error may be raised (zero divide)?",
2707 raise Program_Error;
2710 if K = N_Op_And then
2711 Error_Msg_N ("use `AND THEN` instead of AND?", P);
2713 Error_Msg_N ("use `OR ELSE` instead of OR?", P);
2716 -- If not short-circuited, we need the ckeck
2720 -- If short-circuited, we can omit the check
2727 -----------------------------------
2728 -- Check_Valid_Lvalue_Subscripts --
2729 -----------------------------------
2731 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
2733 -- Skip this if range checks are suppressed
2735 if Range_Checks_Suppressed (Etype (Expr)) then
2738 -- Only do this check for expressions that come from source. We assume
2739 -- that expander generated assignments explicitly include any necessary
2740 -- checks. Note that this is not just an optimization, it avoids
2741 -- infinite recursions!
2743 elsif not Comes_From_Source (Expr) then
2746 -- For a selected component, check the prefix
2748 elsif Nkind (Expr) = N_Selected_Component then
2749 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2752 -- Case of indexed component
2754 elsif Nkind (Expr) = N_Indexed_Component then
2755 Apply_Subscript_Validity_Checks (Expr);
2757 -- Prefix may itself be or contain an indexed component, and these
2758 -- subscripts need checking as well.
2760 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2762 end Check_Valid_Lvalue_Subscripts;
2764 ----------------------------------
2765 -- Null_Exclusion_Static_Checks --
2766 ----------------------------------
2768 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
2769 Error_Node : Node_Id;
2771 Has_Null : constant Boolean := Has_Null_Exclusion (N);
2772 K : constant Node_Kind := Nkind (N);
2777 (K = N_Component_Declaration
2778 or else K = N_Discriminant_Specification
2779 or else K = N_Function_Specification
2780 or else K = N_Object_Declaration
2781 or else K = N_Parameter_Specification);
2783 if K = N_Function_Specification then
2784 Typ := Etype (Defining_Entity (N));
2786 Typ := Etype (Defining_Identifier (N));
2790 when N_Component_Declaration =>
2791 if Present (Access_Definition (Component_Definition (N))) then
2792 Error_Node := Component_Definition (N);
2794 Error_Node := Subtype_Indication (Component_Definition (N));
2797 when N_Discriminant_Specification =>
2798 Error_Node := Discriminant_Type (N);
2800 when N_Function_Specification =>
2801 Error_Node := Result_Definition (N);
2803 when N_Object_Declaration =>
2804 Error_Node := Object_Definition (N);
2806 when N_Parameter_Specification =>
2807 Error_Node := Parameter_Type (N);
2810 raise Program_Error;
2815 -- Enforce legality rule 3.10 (13): A null exclusion can only be
2816 -- applied to an access [sub]type.
2818 if not Is_Access_Type (Typ) then
2820 ("`NOT NULL` allowed only for an access type", Error_Node);
2822 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
2823 -- be applied to a [sub]type that does not exclude null already.
2825 elsif Can_Never_Be_Null (Typ)
2826 and then Comes_From_Source (Typ)
2829 ("`NOT NULL` not allowed (& already excludes null)",
2834 -- Check that null-excluding objects are always initialized, except for
2835 -- deferred constants, for which the expression will appear in the full
2838 if K = N_Object_Declaration
2839 and then No (Expression (N))
2840 and then not Constant_Present (N)
2841 and then not No_Initialization (N)
2843 -- Add an expression that assigns null. This node is needed by
2844 -- Apply_Compile_Time_Constraint_Error, which will replace this with
2845 -- a Constraint_Error node.
2847 Set_Expression (N, Make_Null (Sloc (N)));
2848 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
2850 Apply_Compile_Time_Constraint_Error
2851 (N => Expression (N),
2852 Msg => "(Ada 2005) null-excluding objects must be initialized?",
2853 Reason => CE_Null_Not_Allowed);
2856 -- Check that a null-excluding component, formal or object is not being
2857 -- assigned a null value. Otherwise generate a warning message and
2858 -- replace Expression (N) by an N_Constraint_Error node.
2860 if K /= N_Function_Specification then
2861 Expr := Expression (N);
2863 if Present (Expr) and then Known_Null (Expr) then
2865 when N_Component_Declaration |
2866 N_Discriminant_Specification =>
2867 Apply_Compile_Time_Constraint_Error
2869 Msg => "(Ada 2005) null not allowed " &
2870 "in null-excluding components?",
2871 Reason => CE_Null_Not_Allowed);
2873 when N_Object_Declaration =>
2874 Apply_Compile_Time_Constraint_Error
2876 Msg => "(Ada 2005) null not allowed " &
2877 "in null-excluding objects?",
2878 Reason => CE_Null_Not_Allowed);
2880 when N_Parameter_Specification =>
2881 Apply_Compile_Time_Constraint_Error
2883 Msg => "(Ada 2005) null not allowed " &
2884 "in null-excluding formals?",
2885 Reason => CE_Null_Not_Allowed);
2892 end Null_Exclusion_Static_Checks;
2894 ----------------------------------
2895 -- Conditional_Statements_Begin --
2896 ----------------------------------
2898 procedure Conditional_Statements_Begin is
2900 Saved_Checks_TOS := Saved_Checks_TOS + 1;
2902 -- If stack overflows, kill all checks, that way we know to simply reset
2903 -- the number of saved checks to zero on return. This should never occur
2906 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2909 -- In the normal case, we just make a new stack entry saving the current
2910 -- number of saved checks for a later restore.
2913 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
2915 if Debug_Flag_CC then
2916 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
2920 end Conditional_Statements_Begin;
2922 --------------------------------
2923 -- Conditional_Statements_End --
2924 --------------------------------
2926 procedure Conditional_Statements_End is
2928 pragma Assert (Saved_Checks_TOS > 0);
2930 -- If the saved checks stack overflowed, then we killed all checks, so
2931 -- setting the number of saved checks back to zero is correct. This
2932 -- should never occur in practice.
2934 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2935 Num_Saved_Checks := 0;
2937 -- In the normal case, restore the number of saved checks from the top
2941 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
2942 if Debug_Flag_CC then
2943 w ("Conditional_Statements_End: Num_Saved_Checks = ",
2948 Saved_Checks_TOS := Saved_Checks_TOS - 1;
2949 end Conditional_Statements_End;
2951 ---------------------
2952 -- Determine_Range --
2953 ---------------------
2955 Cache_Size : constant := 2 ** 10;
2956 type Cache_Index is range 0 .. Cache_Size - 1;
2957 -- Determine size of below cache (power of 2 is more efficient!)
2959 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
2960 Determine_Range_Cache_V : array (Cache_Index) of Boolean;
2961 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
2962 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
2963 -- The above arrays are used to implement a small direct cache for
2964 -- Determine_Range calls. Because of the way Determine_Range recursively
2965 -- traces subexpressions, and because overflow checking calls the routine
2966 -- on the way up the tree, a quadratic behavior can otherwise be
2967 -- encountered in large expressions. The cache entry for node N is stored
2968 -- in the (N mod Cache_Size) entry, and can be validated by checking the
2969 -- actual node value stored there. The Range_Cache_V array records the
2970 -- setting of Assume_Valid for the cache entry.
2972 procedure Determine_Range
2977 Assume_Valid : Boolean := False)
2979 Typ : Entity_Id := Etype (N);
2980 -- Type to use, may get reset to base type for possibly invalid entity
2984 -- Lo and Hi bounds of left operand
2988 -- Lo and Hi bounds of right (or only) operand
2991 -- Temp variable used to hold a bound node
2994 -- High bound of base type of expression
2998 -- Refined values for low and high bounds, after tightening
3001 -- Used in lower level calls to indicate if call succeeded
3003 Cindex : Cache_Index;
3004 -- Used to search cache
3006 function OK_Operands return Boolean;
3007 -- Used for binary operators. Determines the ranges of the left and
3008 -- right operands, and if they are both OK, returns True, and puts
3009 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
3015 function OK_Operands return Boolean is
3018 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
3025 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3029 -- Start of processing for Determine_Range
3032 -- Prevent junk warnings by initializing range variables
3039 -- If type is not defined, we can't determine its range
3043 -- We don't deal with anything except discrete types
3045 or else not Is_Discrete_Type (Typ)
3047 -- Ignore type for which an error has been posted, since range in
3048 -- this case may well be a bogosity deriving from the error. Also
3049 -- ignore if error posted on the reference node.
3051 or else Error_Posted (N) or else Error_Posted (Typ)
3057 -- For all other cases, we can determine the range
3061 -- If value is compile time known, then the possible range is the one
3062 -- value that we know this expression definitely has!
3064 if Compile_Time_Known_Value (N) then
3065 Lo := Expr_Value (N);
3070 -- Return if already in the cache
3072 Cindex := Cache_Index (N mod Cache_Size);
3074 if Determine_Range_Cache_N (Cindex) = N
3076 Determine_Range_Cache_V (Cindex) = Assume_Valid
3078 Lo := Determine_Range_Cache_Lo (Cindex);
3079 Hi := Determine_Range_Cache_Hi (Cindex);
3083 -- Otherwise, start by finding the bounds of the type of the expression,
3084 -- the value cannot be outside this range (if it is, then we have an
3085 -- overflow situation, which is a separate check, we are talking here
3086 -- only about the expression value).
3088 -- First a check, never try to find the bounds of a generic type, since
3089 -- these bounds are always junk values, and it is only valid to look at
3090 -- the bounds in an instance.
3092 if Is_Generic_Type (Typ) then
3097 -- First step, change to use base type unless we know the value is valid
3099 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
3100 or else Assume_No_Invalid_Values
3101 or else Assume_Valid
3105 Typ := Underlying_Type (Base_Type (Typ));
3108 -- We use the actual bound unless it is dynamic, in which case use the
3109 -- corresponding base type bound if possible. If we can't get a bound
3110 -- then we figure we can't determine the range (a peculiar case, that
3111 -- perhaps cannot happen, but there is no point in bombing in this
3112 -- optimization circuit.
3114 -- First the low bound
3116 Bound := Type_Low_Bound (Typ);
3118 if Compile_Time_Known_Value (Bound) then
3119 Lo := Expr_Value (Bound);
3121 elsif Compile_Time_Known_Value (Type_Low_Bound (Base_Type (Typ))) then
3122 Lo := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
3129 -- Now the high bound
3131 Bound := Type_High_Bound (Typ);
3133 -- We need the high bound of the base type later on, and this should
3134 -- always be compile time known. Again, it is not clear that this
3135 -- can ever be false, but no point in bombing.
3137 if Compile_Time_Known_Value (Type_High_Bound (Base_Type (Typ))) then
3138 Hbound := Expr_Value (Type_High_Bound (Base_Type (Typ)));
3146 -- If we have a static subtype, then that may have a tighter bound so
3147 -- use the upper bound of the subtype instead in this case.
3149 if Compile_Time_Known_Value (Bound) then
3150 Hi := Expr_Value (Bound);
3153 -- We may be able to refine this value in certain situations. If any
3154 -- refinement is possible, then Lor and Hir are set to possibly tighter
3155 -- bounds, and OK1 is set to True.
3159 -- For unary plus, result is limited by range of operand
3163 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
3165 -- For unary minus, determine range of operand, and negate it
3169 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
3176 -- For binary addition, get range of each operand and do the
3177 -- addition to get the result range.
3181 Lor := Lo_Left + Lo_Right;
3182 Hir := Hi_Left + Hi_Right;
3185 -- Division is tricky. The only case we consider is where the right
3186 -- operand is a positive constant, and in this case we simply divide
3187 -- the bounds of the left operand
3191 if Lo_Right = Hi_Right
3192 and then Lo_Right > 0
3194 Lor := Lo_Left / Lo_Right;
3195 Hir := Hi_Left / Lo_Right;
3202 -- For binary subtraction, get range of each operand and do the worst
3203 -- case subtraction to get the result range.
3205 when N_Op_Subtract =>
3207 Lor := Lo_Left - Hi_Right;
3208 Hir := Hi_Left - Lo_Right;
3211 -- For MOD, if right operand is a positive constant, then result must
3212 -- be in the allowable range of mod results.
3216 if Lo_Right = Hi_Right
3217 and then Lo_Right /= 0
3219 if Lo_Right > 0 then
3221 Hir := Lo_Right - 1;
3223 else -- Lo_Right < 0
3224 Lor := Lo_Right + 1;
3233 -- For REM, if right operand is a positive constant, then result must
3234 -- be in the allowable range of mod results.
3238 if Lo_Right = Hi_Right
3239 and then Lo_Right /= 0
3242 Dval : constant Uint := (abs Lo_Right) - 1;
3245 -- The sign of the result depends on the sign of the
3246 -- dividend (but not on the sign of the divisor, hence
3247 -- the abs operation above).
3267 -- Attribute reference cases
3269 when N_Attribute_Reference =>
3270 case Attribute_Name (N) is
3272 -- For Pos/Val attributes, we can refine the range using the
3273 -- possible range of values of the attribute expression.
3275 when Name_Pos | Name_Val =>
3277 (First (Expressions (N)), OK1, Lor, Hir, Assume_Valid);
3279 -- For Length attribute, use the bounds of the corresponding
3280 -- index type to refine the range.
3284 Atyp : Entity_Id := Etype (Prefix (N));
3292 if Is_Access_Type (Atyp) then
3293 Atyp := Designated_Type (Atyp);
3296 -- For string literal, we know exact value
3298 if Ekind (Atyp) = E_String_Literal_Subtype then
3300 Lo := String_Literal_Length (Atyp);
3301 Hi := String_Literal_Length (Atyp);
3305 -- Otherwise check for expression given
3307 if No (Expressions (N)) then
3311 UI_To_Int (Expr_Value (First (Expressions (N))));
3314 Indx := First_Index (Atyp);
3315 for J in 2 .. Inum loop
3316 Indx := Next_Index (Indx);
3320 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU,
3325 (Type_High_Bound (Etype (Indx)), OK1, UL, UU,
3330 -- The maximum value for Length is the biggest
3331 -- possible gap between the values of the bounds.
3332 -- But of course, this value cannot be negative.
3334 Hir := UI_Max (Uint_0, UU - LL + 1);
3336 -- For constrained arrays, the minimum value for
3337 -- Length is taken from the actual value of the
3338 -- bounds, since the index will be exactly of
3341 if Is_Constrained (Atyp) then
3342 Lor := UI_Max (Uint_0, UL - LU + 1);
3344 -- For an unconstrained array, the minimum value
3345 -- for length is always zero.
3354 -- No special handling for other attributes
3355 -- Probably more opportunities exist here ???
3362 -- For type conversion from one discrete type to another, we can
3363 -- refine the range using the converted value.
3365 when N_Type_Conversion =>
3366 Determine_Range (Expression (N), OK1, Lor, Hir, Assume_Valid);
3368 -- Nothing special to do for all other expression kinds
3376 -- At this stage, if OK1 is true, then we know that the actual
3377 -- result of the computed expression is in the range Lor .. Hir.
3378 -- We can use this to restrict the possible range of results.
3382 -- If the refined value of the low bound is greater than the
3383 -- type high bound, then reset it to the more restrictive
3384 -- value. However, we do NOT do this for the case of a modular
3385 -- type where the possible upper bound on the value is above the
3386 -- base type high bound, because that means the result could wrap.
3389 and then not (Is_Modular_Integer_Type (Typ)
3390 and then Hir > Hbound)
3395 -- Similarly, if the refined value of the high bound is less
3396 -- than the value so far, then reset it to the more restrictive
3397 -- value. Again, we do not do this if the refined low bound is
3398 -- negative for a modular type, since this would wrap.
3401 and then not (Is_Modular_Integer_Type (Typ)
3402 and then Lor < Uint_0)
3408 -- Set cache entry for future call and we are all done
3410 Determine_Range_Cache_N (Cindex) := N;
3411 Determine_Range_Cache_V (Cindex) := Assume_Valid;
3412 Determine_Range_Cache_Lo (Cindex) := Lo;
3413 Determine_Range_Cache_Hi (Cindex) := Hi;
3416 -- If any exception occurs, it means that we have some bug in the compiler
3417 -- possibly triggered by a previous error, or by some unforseen peculiar
3418 -- occurrence. However, this is only an optimization attempt, so there is
3419 -- really no point in crashing the compiler. Instead we just decide, too
3420 -- bad, we can't figure out a range in this case after all.
3425 -- Debug flag K disables this behavior (useful for debugging)
3427 if Debug_Flag_K then
3435 end Determine_Range;
3437 ------------------------------------
3438 -- Discriminant_Checks_Suppressed --
3439 ------------------------------------
3441 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
3444 if Is_Unchecked_Union (E) then
3446 elsif Checks_May_Be_Suppressed (E) then
3447 return Is_Check_Suppressed (E, Discriminant_Check);
3451 return Scope_Suppress (Discriminant_Check);
3452 end Discriminant_Checks_Suppressed;
3454 --------------------------------
3455 -- Division_Checks_Suppressed --
3456 --------------------------------
3458 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
3460 if Present (E) and then Checks_May_Be_Suppressed (E) then
3461 return Is_Check_Suppressed (E, Division_Check);
3463 return Scope_Suppress (Division_Check);
3465 end Division_Checks_Suppressed;
3467 -----------------------------------
3468 -- Elaboration_Checks_Suppressed --
3469 -----------------------------------
3471 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
3473 -- The complication in this routine is that if we are in the dynamic
3474 -- model of elaboration, we also check All_Checks, since All_Checks
3475 -- does not set Elaboration_Check explicitly.
3478 if Kill_Elaboration_Checks (E) then
3481 elsif Checks_May_Be_Suppressed (E) then
3482 if Is_Check_Suppressed (E, Elaboration_Check) then
3484 elsif Dynamic_Elaboration_Checks then
3485 return Is_Check_Suppressed (E, All_Checks);
3492 if Scope_Suppress (Elaboration_Check) then
3494 elsif Dynamic_Elaboration_Checks then
3495 return Scope_Suppress (All_Checks);
3499 end Elaboration_Checks_Suppressed;
3501 ---------------------------
3502 -- Enable_Overflow_Check --
3503 ---------------------------
3505 procedure Enable_Overflow_Check (N : Node_Id) is
3506 Typ : constant Entity_Id := Base_Type (Etype (N));
3515 if Debug_Flag_CC then
3516 w ("Enable_Overflow_Check for node ", Int (N));
3517 Write_Str (" Source location = ");
3522 -- No check if overflow checks suppressed for type of node
3524 if Present (Etype (N))
3525 and then Overflow_Checks_Suppressed (Etype (N))
3529 -- Nothing to do for unsigned integer types, which do not overflow
3531 elsif Is_Modular_Integer_Type (Typ) then
3534 -- Nothing to do if the range of the result is known OK. We skip this
3535 -- for conversions, since the caller already did the check, and in any
3536 -- case the condition for deleting the check for a type conversion is
3539 elsif Nkind (N) /= N_Type_Conversion then
3540 Determine_Range (N, OK, Lo, Hi, Assume_Valid => True);
3542 -- Note in the test below that we assume that the range is not OK
3543 -- if a bound of the range is equal to that of the type. That's not
3544 -- quite accurate but we do this for the following reasons:
3546 -- a) The way that Determine_Range works, it will typically report
3547 -- the bounds of the value as being equal to the bounds of the
3548 -- type, because it either can't tell anything more precise, or
3549 -- does not think it is worth the effort to be more precise.
3551 -- b) It is very unusual to have a situation in which this would
3552 -- generate an unnecessary overflow check (an example would be
3553 -- a subtype with a range 0 .. Integer'Last - 1 to which the
3554 -- literal value one is added).
3556 -- c) The alternative is a lot of special casing in this routine
3557 -- which would partially duplicate Determine_Range processing.
3560 and then Lo > Expr_Value (Type_Low_Bound (Typ))
3561 and then Hi < Expr_Value (Type_High_Bound (Typ))
3563 if Debug_Flag_CC then
3564 w ("No overflow check required");
3571 -- If not in optimizing mode, set flag and we are done. We are also done
3572 -- (and just set the flag) if the type is not a discrete type, since it
3573 -- is not worth the effort to eliminate checks for other than discrete
3574 -- types. In addition, we take this same path if we have stored the
3575 -- maximum number of checks possible already (a very unlikely situation,
3576 -- but we do not want to blow up!)
3578 if Optimization_Level = 0
3579 or else not Is_Discrete_Type (Etype (N))
3580 or else Num_Saved_Checks = Saved_Checks'Last
3582 Activate_Overflow_Check (N);
3584 if Debug_Flag_CC then
3585 w ("Optimization off");
3591 -- Otherwise evaluate and check the expression
3596 Target_Type => Empty,
3602 if Debug_Flag_CC then
3603 w ("Called Find_Check");
3607 w (" Check_Num = ", Chk);
3608 w (" Ent = ", Int (Ent));
3609 Write_Str (" Ofs = ");
3614 -- If check is not of form to optimize, then set flag and we are done
3617 Activate_Overflow_Check (N);
3621 -- If check is already performed, then return without setting flag
3624 if Debug_Flag_CC then
3625 w ("Check suppressed!");
3631 -- Here we will make a new entry for the new check
3633 Activate_Overflow_Check (N);
3634 Num_Saved_Checks := Num_Saved_Checks + 1;
3635 Saved_Checks (Num_Saved_Checks) :=
3640 Target_Type => Empty);
3642 if Debug_Flag_CC then
3643 w ("Make new entry, check number = ", Num_Saved_Checks);
3644 w (" Entity = ", Int (Ent));
3645 Write_Str (" Offset = ");
3647 w (" Check_Type = O");
3648 w (" Target_Type = Empty");
3651 -- If we get an exception, then something went wrong, probably because of
3652 -- an error in the structure of the tree due to an incorrect program. Or it
3653 -- may be a bug in the optimization circuit. In either case the safest
3654 -- thing is simply to set the check flag unconditionally.
3658 Activate_Overflow_Check (N);
3660 if Debug_Flag_CC then
3661 w (" exception occurred, overflow flag set");
3665 end Enable_Overflow_Check;
3667 ------------------------
3668 -- Enable_Range_Check --
3669 ------------------------
3671 procedure Enable_Range_Check (N : Node_Id) is
3680 -- Return if unchecked type conversion with range check killed. In this
3681 -- case we never set the flag (that's what Kill_Range_Check is about!)
3683 if Nkind (N) = N_Unchecked_Type_Conversion
3684 and then Kill_Range_Check (N)
3689 -- Check for various cases where we should suppress the range check
3691 -- No check if range checks suppressed for type of node
3693 if Present (Etype (N))
3694 and then Range_Checks_Suppressed (Etype (N))
3698 -- No check if node is an entity name, and range checks are suppressed
3699 -- for this entity, or for the type of this entity.
3701 elsif Is_Entity_Name (N)
3702 and then (Range_Checks_Suppressed (Entity (N))
3703 or else Range_Checks_Suppressed (Etype (Entity (N))))
3707 -- No checks if index of array, and index checks are suppressed for
3708 -- the array object or the type of the array.
3710 elsif Nkind (Parent (N)) = N_Indexed_Component then
3712 Pref : constant Node_Id := Prefix (Parent (N));
3714 if Is_Entity_Name (Pref)
3715 and then Index_Checks_Suppressed (Entity (Pref))
3718 elsif Index_Checks_Suppressed (Etype (Pref)) then
3724 -- Debug trace output
3726 if Debug_Flag_CC then
3727 w ("Enable_Range_Check for node ", Int (N));
3728 Write_Str (" Source location = ");
3733 -- If not in optimizing mode, set flag and we are done. We are also done
3734 -- (and just set the flag) if the type is not a discrete type, since it
3735 -- is not worth the effort to eliminate checks for other than discrete
3736 -- types. In addition, we take this same path if we have stored the
3737 -- maximum number of checks possible already (a very unlikely situation,
3738 -- but we do not want to blow up!)
3740 if Optimization_Level = 0
3741 or else No (Etype (N))
3742 or else not Is_Discrete_Type (Etype (N))
3743 or else Num_Saved_Checks = Saved_Checks'Last
3745 Activate_Range_Check (N);
3747 if Debug_Flag_CC then
3748 w ("Optimization off");
3754 -- Otherwise find out the target type
3758 -- For assignment, use left side subtype
3760 if Nkind (P) = N_Assignment_Statement
3761 and then Expression (P) = N
3763 Ttyp := Etype (Name (P));
3765 -- For indexed component, use subscript subtype
3767 elsif Nkind (P) = N_Indexed_Component then
3774 Atyp := Etype (Prefix (P));
3776 if Is_Access_Type (Atyp) then
3777 Atyp := Designated_Type (Atyp);
3779 -- If the prefix is an access to an unconstrained array,
3780 -- perform check unconditionally: it depends on the bounds of
3781 -- an object and we cannot currently recognize whether the test
3782 -- may be redundant.
3784 if not Is_Constrained (Atyp) then
3785 Activate_Range_Check (N);
3789 -- Ditto if the prefix is an explicit dereference whose designated
3790 -- type is unconstrained.
3792 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
3793 and then not Is_Constrained (Atyp)
3795 Activate_Range_Check (N);
3799 Indx := First_Index (Atyp);
3800 Subs := First (Expressions (P));
3803 Ttyp := Etype (Indx);
3812 -- For now, ignore all other cases, they are not so interesting
3815 if Debug_Flag_CC then
3816 w (" target type not found, flag set");
3819 Activate_Range_Check (N);
3823 -- Evaluate and check the expression
3828 Target_Type => Ttyp,
3834 if Debug_Flag_CC then
3835 w ("Called Find_Check");
3836 w ("Target_Typ = ", Int (Ttyp));
3840 w (" Check_Num = ", Chk);
3841 w (" Ent = ", Int (Ent));
3842 Write_Str (" Ofs = ");
3847 -- If check is not of form to optimize, then set flag and we are done
3850 if Debug_Flag_CC then
3851 w (" expression not of optimizable type, flag set");
3854 Activate_Range_Check (N);
3858 -- If check is already performed, then return without setting flag
3861 if Debug_Flag_CC then
3862 w ("Check suppressed!");
3868 -- Here we will make a new entry for the new check
3870 Activate_Range_Check (N);
3871 Num_Saved_Checks := Num_Saved_Checks + 1;
3872 Saved_Checks (Num_Saved_Checks) :=
3877 Target_Type => Ttyp);
3879 if Debug_Flag_CC then
3880 w ("Make new entry, check number = ", Num_Saved_Checks);
3881 w (" Entity = ", Int (Ent));
3882 Write_Str (" Offset = ");
3884 w (" Check_Type = R");
3885 w (" Target_Type = ", Int (Ttyp));
3886 pg (Union_Id (Ttyp));
3889 -- If we get an exception, then something went wrong, probably because of
3890 -- an error in the structure of the tree due to an incorrect program. Or
3891 -- it may be a bug in the optimization circuit. In either case the safest
3892 -- thing is simply to set the check flag unconditionally.
3896 Activate_Range_Check (N);
3898 if Debug_Flag_CC then
3899 w (" exception occurred, range flag set");
3903 end Enable_Range_Check;
3909 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
3910 Typ : constant Entity_Id := Etype (Expr);
3913 -- Ignore call if we are not doing any validity checking
3915 if not Validity_Checks_On then
3918 -- Ignore call if range or validity checks suppressed on entity or type
3920 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
3923 -- No check required if expression is from the expander, we assume the
3924 -- expander will generate whatever checks are needed. Note that this is
3925 -- not just an optimization, it avoids infinite recursions!
3927 -- Unchecked conversions must be checked, unless they are initialized
3928 -- scalar values, as in a component assignment in an init proc.
3930 -- In addition, we force a check if Force_Validity_Checks is set
3932 elsif not Comes_From_Source (Expr)
3933 and then not Force_Validity_Checks
3934 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
3935 or else Kill_Range_Check (Expr))
3939 -- No check required if expression is known to have valid value
3941 elsif Expr_Known_Valid (Expr) then
3944 -- Ignore case of enumeration with holes where the flag is set not to
3945 -- worry about holes, since no special validity check is needed
3947 elsif Is_Enumeration_Type (Typ)
3948 and then Has_Non_Standard_Rep (Typ)
3953 -- No check required on the left-hand side of an assignment
3955 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
3956 and then Expr = Name (Parent (Expr))
3960 -- No check on a univeral real constant. The context will eventually
3961 -- convert it to a machine number for some target type, or report an
3964 elsif Nkind (Expr) = N_Real_Literal
3965 and then Etype (Expr) = Universal_Real
3969 -- If the expression denotes a component of a packed boolean arrray,
3970 -- no possible check applies. We ignore the old ACATS chestnuts that
3971 -- involve Boolean range True..True.
3973 -- Note: validity checks are generated for expressions that yield a
3974 -- scalar type, when it is possible to create a value that is outside of
3975 -- the type. If this is a one-bit boolean no such value exists. This is
3976 -- an optimization, and it also prevents compiler blowing up during the
3977 -- elaboration of improperly expanded packed array references.
3979 elsif Nkind (Expr) = N_Indexed_Component
3980 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
3981 and then Root_Type (Etype (Expr)) = Standard_Boolean
3985 -- An annoying special case. If this is an out parameter of a scalar
3986 -- type, then the value is not going to be accessed, therefore it is
3987 -- inappropriate to do any validity check at the call site.
3990 -- Only need to worry about scalar types
3992 if Is_Scalar_Type (Typ) then
4002 -- Find actual argument (which may be a parameter association)
4003 -- and the parent of the actual argument (the call statement)
4008 if Nkind (P) = N_Parameter_Association then
4013 -- Only need to worry if we are argument of a procedure call
4014 -- since functions don't have out parameters. If this is an
4015 -- indirect or dispatching call, get signature from the
4018 if Nkind (P) = N_Procedure_Call_Statement then
4019 L := Parameter_Associations (P);
4021 if Is_Entity_Name (Name (P)) then
4022 E := Entity (Name (P));
4024 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
4025 E := Etype (Name (P));
4028 -- Only need to worry if there are indeed actuals, and if
4029 -- this could be a procedure call, otherwise we cannot get a
4030 -- match (either we are not an argument, or the mode of the
4031 -- formal is not OUT). This test also filters out the
4034 if Is_Non_Empty_List (L)
4035 and then Is_Subprogram (E)
4037 -- This is the loop through parameters, looking for an
4038 -- OUT parameter for which we are the argument.
4040 F := First_Formal (E);
4042 while Present (F) loop
4043 if Ekind (F) = E_Out_Parameter and then A = N then
4056 -- If we fall through, a validity check is required
4058 Insert_Valid_Check (Expr);
4060 if Is_Entity_Name (Expr)
4061 and then Safe_To_Capture_Value (Expr, Entity (Expr))
4063 Set_Is_Known_Valid (Entity (Expr));
4067 ----------------------
4068 -- Expr_Known_Valid --
4069 ----------------------
4071 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
4072 Typ : constant Entity_Id := Etype (Expr);
4075 -- Non-scalar types are always considered valid, since they never give
4076 -- rise to the issues of erroneous or bounded error behavior that are
4077 -- the concern. In formal reference manual terms the notion of validity
4078 -- only applies to scalar types. Note that even when packed arrays are
4079 -- represented using modular types, they are still arrays semantically,
4080 -- so they are also always valid (in particular, the unused bits can be
4081 -- random rubbish without affecting the validity of the array value).
4083 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
4086 -- If no validity checking, then everything is considered valid
4088 elsif not Validity_Checks_On then
4091 -- Floating-point types are considered valid unless floating-point
4092 -- validity checks have been specifically turned on.
4094 elsif Is_Floating_Point_Type (Typ)
4095 and then not Validity_Check_Floating_Point
4099 -- If the expression is the value of an object that is known to be
4100 -- valid, then clearly the expression value itself is valid.
4102 elsif Is_Entity_Name (Expr)
4103 and then Is_Known_Valid (Entity (Expr))
4107 -- References to discriminants are always considered valid. The value
4108 -- of a discriminant gets checked when the object is built. Within the
4109 -- record, we consider it valid, and it is important to do so, since
4110 -- otherwise we can try to generate bogus validity checks which
4111 -- reference discriminants out of scope. Discriminants of concurrent
4112 -- types are excluded for the same reason.
4114 elsif Is_Entity_Name (Expr)
4115 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
4119 -- If the type is one for which all values are known valid, then we are
4120 -- sure that the value is valid except in the slightly odd case where
4121 -- the expression is a reference to a variable whose size has been
4122 -- explicitly set to a value greater than the object size.
4124 elsif Is_Known_Valid (Typ) then
4125 if Is_Entity_Name (Expr)
4126 and then Ekind (Entity (Expr)) = E_Variable
4127 and then Esize (Entity (Expr)) > Esize (Typ)
4134 -- Integer and character literals always have valid values, where
4135 -- appropriate these will be range checked in any case.
4137 elsif Nkind (Expr) = N_Integer_Literal
4139 Nkind (Expr) = N_Character_Literal
4143 -- If we have a type conversion or a qualification of a known valid
4144 -- value, then the result will always be valid.
4146 elsif Nkind (Expr) = N_Type_Conversion
4148 Nkind (Expr) = N_Qualified_Expression
4150 return Expr_Known_Valid (Expression (Expr));
4152 -- The result of any operator is always considered valid, since we
4153 -- assume the necessary checks are done by the operator. For operators
4154 -- on floating-point operations, we must also check when the operation
4155 -- is the right-hand side of an assignment, or is an actual in a call.
4157 elsif Nkind (Expr) in N_Op then
4158 if Is_Floating_Point_Type (Typ)
4159 and then Validity_Check_Floating_Point
4161 (Nkind (Parent (Expr)) = N_Assignment_Statement
4162 or else Nkind (Parent (Expr)) = N_Function_Call
4163 or else Nkind (Parent (Expr)) = N_Parameter_Association)
4170 -- The result of a membership test is always valid, since it is true or
4171 -- false, there are no other possibilities.
4173 elsif Nkind (Expr) in N_Membership_Test then
4176 -- For all other cases, we do not know the expression is valid
4181 end Expr_Known_Valid;
4187 procedure Find_Check
4189 Check_Type : Character;
4190 Target_Type : Entity_Id;
4191 Entry_OK : out Boolean;
4192 Check_Num : out Nat;
4193 Ent : out Entity_Id;
4196 function Within_Range_Of
4197 (Target_Type : Entity_Id;
4198 Check_Type : Entity_Id) return Boolean;
4199 -- Given a requirement for checking a range against Target_Type, and
4200 -- and a range Check_Type against which a check has already been made,
4201 -- determines if the check against check type is sufficient to ensure
4202 -- that no check against Target_Type is required.
4204 ---------------------
4205 -- Within_Range_Of --
4206 ---------------------
4208 function Within_Range_Of
4209 (Target_Type : Entity_Id;
4210 Check_Type : Entity_Id) return Boolean
4213 if Target_Type = Check_Type then
4218 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
4219 Thi : constant Node_Id := Type_High_Bound (Target_Type);
4220 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
4221 Chi : constant Node_Id := Type_High_Bound (Check_Type);
4225 or else (Compile_Time_Known_Value (Tlo)
4227 Compile_Time_Known_Value (Clo)
4229 Expr_Value (Clo) >= Expr_Value (Tlo)))
4232 or else (Compile_Time_Known_Value (Thi)
4234 Compile_Time_Known_Value (Chi)
4236 Expr_Value (Chi) <= Expr_Value (Clo)))
4244 end Within_Range_Of;
4246 -- Start of processing for Find_Check
4249 -- Establish default, to avoid warnings from GCC
4253 -- Case of expression is simple entity reference
4255 if Is_Entity_Name (Expr) then
4256 Ent := Entity (Expr);
4259 -- Case of expression is entity + known constant
4261 elsif Nkind (Expr) = N_Op_Add
4262 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4263 and then Is_Entity_Name (Left_Opnd (Expr))
4265 Ent := Entity (Left_Opnd (Expr));
4266 Ofs := Expr_Value (Right_Opnd (Expr));
4268 -- Case of expression is entity - known constant
4270 elsif Nkind (Expr) = N_Op_Subtract
4271 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4272 and then Is_Entity_Name (Left_Opnd (Expr))
4274 Ent := Entity (Left_Opnd (Expr));
4275 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
4277 -- Any other expression is not of the right form
4286 -- Come here with expression of appropriate form, check if entity is an
4287 -- appropriate one for our purposes.
4289 if (Ekind (Ent) = E_Variable
4290 or else Is_Constant_Object (Ent))
4291 and then not Is_Library_Level_Entity (Ent)
4299 -- See if there is matching check already
4301 for J in reverse 1 .. Num_Saved_Checks loop
4303 SC : Saved_Check renames Saved_Checks (J);
4306 if SC.Killed = False
4307 and then SC.Entity = Ent
4308 and then SC.Offset = Ofs
4309 and then SC.Check_Type = Check_Type
4310 and then Within_Range_Of (Target_Type, SC.Target_Type)
4318 -- If we fall through entry was not found
4324 ---------------------------------
4325 -- Generate_Discriminant_Check --
4326 ---------------------------------
4328 -- Note: the code for this procedure is derived from the
4329 -- Emit_Discriminant_Check Routine in trans.c.
4331 procedure Generate_Discriminant_Check (N : Node_Id) is
4332 Loc : constant Source_Ptr := Sloc (N);
4333 Pref : constant Node_Id := Prefix (N);
4334 Sel : constant Node_Id := Selector_Name (N);
4336 Orig_Comp : constant Entity_Id :=
4337 Original_Record_Component (Entity (Sel));
4338 -- The original component to be checked
4340 Discr_Fct : constant Entity_Id :=
4341 Discriminant_Checking_Func (Orig_Comp);
4342 -- The discriminant checking function
4345 -- One discriminant to be checked in the type
4347 Real_Discr : Entity_Id;
4348 -- Actual discriminant in the call
4350 Pref_Type : Entity_Id;
4351 -- Type of relevant prefix (ignoring private/access stuff)
4354 -- List of arguments for function call
4357 -- Keep track of the formal corresponding to the actual we build for
4358 -- each discriminant, in order to be able to perform the necessary type
4362 -- Selected component reference for checking function argument
4365 Pref_Type := Etype (Pref);
4367 -- Force evaluation of the prefix, so that it does not get evaluated
4368 -- twice (once for the check, once for the actual reference). Such a
4369 -- double evaluation is always a potential source of inefficiency,
4370 -- and is functionally incorrect in the volatile case, or when the
4371 -- prefix may have side-effects. An entity or a component of an
4372 -- entity requires no evaluation.
4374 if Is_Entity_Name (Pref) then
4375 if Treat_As_Volatile (Entity (Pref)) then
4376 Force_Evaluation (Pref, Name_Req => True);
4379 elsif Treat_As_Volatile (Etype (Pref)) then
4380 Force_Evaluation (Pref, Name_Req => True);
4382 elsif Nkind (Pref) = N_Selected_Component
4383 and then Is_Entity_Name (Prefix (Pref))
4388 Force_Evaluation (Pref, Name_Req => True);
4391 -- For a tagged type, use the scope of the original component to
4392 -- obtain the type, because ???
4394 if Is_Tagged_Type (Scope (Orig_Comp)) then
4395 Pref_Type := Scope (Orig_Comp);
4397 -- For an untagged derived type, use the discriminants of the parent
4398 -- which have been renamed in the derivation, possibly by a one-to-many
4399 -- discriminant constraint. For non-tagged type, initially get the Etype
4403 if Is_Derived_Type (Pref_Type)
4404 and then Number_Discriminants (Pref_Type) /=
4405 Number_Discriminants (Etype (Base_Type (Pref_Type)))
4407 Pref_Type := Etype (Base_Type (Pref_Type));
4411 -- We definitely should have a checking function, This routine should
4412 -- not be called if no discriminant checking function is present.
4414 pragma Assert (Present (Discr_Fct));
4416 -- Create the list of the actual parameters for the call. This list
4417 -- is the list of the discriminant fields of the record expression to
4418 -- be discriminant checked.
4421 Formal := First_Formal (Discr_Fct);
4422 Discr := First_Discriminant (Pref_Type);
4423 while Present (Discr) loop
4425 -- If we have a corresponding discriminant field, and a parent
4426 -- subtype is present, then we want to use the corresponding
4427 -- discriminant since this is the one with the useful value.
4429 if Present (Corresponding_Discriminant (Discr))
4430 and then Ekind (Pref_Type) = E_Record_Type
4431 and then Present (Parent_Subtype (Pref_Type))
4433 Real_Discr := Corresponding_Discriminant (Discr);
4435 Real_Discr := Discr;
4438 -- Construct the reference to the discriminant
4441 Make_Selected_Component (Loc,
4443 Unchecked_Convert_To (Pref_Type,
4444 Duplicate_Subexpr (Pref)),
4445 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
4447 -- Manually analyze and resolve this selected component. We really
4448 -- want it just as it appears above, and do not want the expander
4449 -- playing discriminal games etc with this reference. Then we append
4450 -- the argument to the list we are gathering.
4452 Set_Etype (Scomp, Etype (Real_Discr));
4453 Set_Analyzed (Scomp, True);
4454 Append_To (Args, Convert_To (Etype (Formal), Scomp));
4456 Next_Formal_With_Extras (Formal);
4457 Next_Discriminant (Discr);
4460 -- Now build and insert the call
4463 Make_Raise_Constraint_Error (Loc,
4465 Make_Function_Call (Loc,
4466 Name => New_Occurrence_Of (Discr_Fct, Loc),
4467 Parameter_Associations => Args),
4468 Reason => CE_Discriminant_Check_Failed));
4469 end Generate_Discriminant_Check;
4471 ---------------------------
4472 -- Generate_Index_Checks --
4473 ---------------------------
4475 procedure Generate_Index_Checks (N : Node_Id) is
4476 Loc : constant Source_Ptr := Sloc (N);
4477 A : constant Node_Id := Prefix (N);
4483 -- Ignore call if index checks suppressed for array object or type
4485 if (Is_Entity_Name (A) and then Index_Checks_Suppressed (Entity (A)))
4486 or else Index_Checks_Suppressed (Etype (A))
4491 -- Generate the checks
4493 Sub := First (Expressions (N));
4495 while Present (Sub) loop
4496 if Do_Range_Check (Sub) then
4497 Set_Do_Range_Check (Sub, False);
4499 -- Force evaluation except for the case of a simple name of a
4500 -- non-volatile entity.
4502 if not Is_Entity_Name (Sub)
4503 or else Treat_As_Volatile (Entity (Sub))
4505 Force_Evaluation (Sub);
4508 -- Generate a raise of constraint error with the appropriate
4509 -- reason and a condition of the form:
4511 -- Base_Type(Sub) not in array'range (subscript)
4513 -- Note that the reason we generate the conversion to the base
4514 -- type here is that we definitely want the range check to take
4515 -- place, even if it looks like the subtype is OK. Optimization
4516 -- considerations that allow us to omit the check have already
4517 -- been taken into account in the setting of the Do_Range_Check
4523 Num := New_List (Make_Integer_Literal (Loc, Ind));
4527 Make_Raise_Constraint_Error (Loc,
4531 Convert_To (Base_Type (Etype (Sub)),
4532 Duplicate_Subexpr_Move_Checks (Sub)),
4534 Make_Attribute_Reference (Loc,
4536 Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
4537 Attribute_Name => Name_Range,
4538 Expressions => Num)),
4539 Reason => CE_Index_Check_Failed));
4545 end Generate_Index_Checks;
4547 --------------------------
4548 -- Generate_Range_Check --
4549 --------------------------
4551 procedure Generate_Range_Check
4553 Target_Type : Entity_Id;
4554 Reason : RT_Exception_Code)
4556 Loc : constant Source_Ptr := Sloc (N);
4557 Source_Type : constant Entity_Id := Etype (N);
4558 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
4559 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
4562 -- First special case, if the source type is already within the range
4563 -- of the target type, then no check is needed (probably we should have
4564 -- stopped Do_Range_Check from being set in the first place, but better
4565 -- late than later in preventing junk code!
4567 -- We do NOT apply this if the source node is a literal, since in this
4568 -- case the literal has already been labeled as having the subtype of
4571 if In_Subrange_Of (Source_Type, Target_Type)
4573 (Nkind (N) = N_Integer_Literal
4575 Nkind (N) = N_Real_Literal
4577 Nkind (N) = N_Character_Literal
4580 and then Ekind (Entity (N)) = E_Enumeration_Literal))
4585 -- We need a check, so force evaluation of the node, so that it does
4586 -- not get evaluated twice (once for the check, once for the actual
4587 -- reference). Such a double evaluation is always a potential source
4588 -- of inefficiency, and is functionally incorrect in the volatile case.
4590 if not Is_Entity_Name (N)
4591 or else Treat_As_Volatile (Entity (N))
4593 Force_Evaluation (N);
4596 -- The easiest case is when Source_Base_Type and Target_Base_Type are
4597 -- the same since in this case we can simply do a direct check of the
4598 -- value of N against the bounds of Target_Type.
4600 -- [constraint_error when N not in Target_Type]
4602 -- Note: this is by far the most common case, for example all cases of
4603 -- checks on the RHS of assignments are in this category, but not all
4604 -- cases are like this. Notably conversions can involve two types.
4606 if Source_Base_Type = Target_Base_Type then
4608 Make_Raise_Constraint_Error (Loc,
4611 Left_Opnd => Duplicate_Subexpr (N),
4612 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4615 -- Next test for the case where the target type is within the bounds
4616 -- of the base type of the source type, since in this case we can
4617 -- simply convert these bounds to the base type of T to do the test.
4619 -- [constraint_error when N not in
4620 -- Source_Base_Type (Target_Type'First)
4622 -- Source_Base_Type(Target_Type'Last))]
4624 -- The conversions will always work and need no check
4626 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
4627 -- of converting from an enumeration value to an integer type, such as
4628 -- occurs for the case of generating a range check on Enum'Val(Exp)
4629 -- (which used to be handled by gigi). This is OK, since the conversion
4630 -- itself does not require a check.
4632 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
4634 Make_Raise_Constraint_Error (Loc,
4637 Left_Opnd => Duplicate_Subexpr (N),
4642 Unchecked_Convert_To (Source_Base_Type,
4643 Make_Attribute_Reference (Loc,
4645 New_Occurrence_Of (Target_Type, Loc),
4646 Attribute_Name => Name_First)),
4649 Unchecked_Convert_To (Source_Base_Type,
4650 Make_Attribute_Reference (Loc,
4652 New_Occurrence_Of (Target_Type, Loc),
4653 Attribute_Name => Name_Last)))),
4656 -- Note that at this stage we now that the Target_Base_Type is not in
4657 -- the range of the Source_Base_Type (since even the Target_Type itself
4658 -- is not in this range). It could still be the case that Source_Type is
4659 -- in range of the target base type since we have not checked that case.
4661 -- If that is the case, we can freely convert the source to the target,
4662 -- and then test the target result against the bounds.
4664 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
4666 -- We make a temporary to hold the value of the converted value
4667 -- (converted to the base type), and then we will do the test against
4670 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
4671 -- [constraint_error when Tnn not in Target_Type]
4673 -- Then the conversion itself is replaced by an occurrence of Tnn
4676 Tnn : constant Entity_Id :=
4677 Make_Defining_Identifier (Loc,
4678 Chars => New_Internal_Name ('T'));
4681 Insert_Actions (N, New_List (
4682 Make_Object_Declaration (Loc,
4683 Defining_Identifier => Tnn,
4684 Object_Definition =>
4685 New_Occurrence_Of (Target_Base_Type, Loc),
4686 Constant_Present => True,
4688 Make_Type_Conversion (Loc,
4689 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
4690 Expression => Duplicate_Subexpr (N))),
4692 Make_Raise_Constraint_Error (Loc,
4695 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4696 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4698 Reason => Reason)));
4700 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4702 -- Set the type of N, because the declaration for Tnn might not
4703 -- be analyzed yet, as is the case if N appears within a record
4704 -- declaration, as a discriminant constraint or expression.
4706 Set_Etype (N, Target_Base_Type);
4709 -- At this stage, we know that we have two scalar types, which are
4710 -- directly convertible, and where neither scalar type has a base
4711 -- range that is in the range of the other scalar type.
4713 -- The only way this can happen is with a signed and unsigned type.
4714 -- So test for these two cases:
4717 -- Case of the source is unsigned and the target is signed
4719 if Is_Unsigned_Type (Source_Base_Type)
4720 and then not Is_Unsigned_Type (Target_Base_Type)
4722 -- If the source is unsigned and the target is signed, then we
4723 -- know that the source is not shorter than the target (otherwise
4724 -- the source base type would be in the target base type range).
4726 -- In other words, the unsigned type is either the same size as
4727 -- the target, or it is larger. It cannot be smaller.
4730 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
4732 -- We only need to check the low bound if the low bound of the
4733 -- target type is non-negative. If the low bound of the target
4734 -- type is negative, then we know that we will fit fine.
4736 -- If the high bound of the target type is negative, then we
4737 -- know we have a constraint error, since we can't possibly
4738 -- have a negative source.
4740 -- With these two checks out of the way, we can do the check
4741 -- using the source type safely
4743 -- This is definitely the most annoying case!
4745 -- [constraint_error
4746 -- when (Target_Type'First >= 0
4748 -- N < Source_Base_Type (Target_Type'First))
4749 -- or else Target_Type'Last < 0
4750 -- or else N > Source_Base_Type (Target_Type'Last)];
4752 -- We turn off all checks since we know that the conversions
4753 -- will work fine, given the guards for negative values.
4756 Make_Raise_Constraint_Error (Loc,
4762 Left_Opnd => Make_Op_Ge (Loc,
4764 Make_Attribute_Reference (Loc,
4766 New_Occurrence_Of (Target_Type, Loc),
4767 Attribute_Name => Name_First),
4768 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4772 Left_Opnd => Duplicate_Subexpr (N),
4774 Convert_To (Source_Base_Type,
4775 Make_Attribute_Reference (Loc,
4777 New_Occurrence_Of (Target_Type, Loc),
4778 Attribute_Name => Name_First)))),
4783 Make_Attribute_Reference (Loc,
4784 Prefix => New_Occurrence_Of (Target_Type, Loc),
4785 Attribute_Name => Name_Last),
4786 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
4790 Left_Opnd => Duplicate_Subexpr (N),
4792 Convert_To (Source_Base_Type,
4793 Make_Attribute_Reference (Loc,
4794 Prefix => New_Occurrence_Of (Target_Type, Loc),
4795 Attribute_Name => Name_Last)))),
4798 Suppress => All_Checks);
4800 -- Only remaining possibility is that the source is signed and
4801 -- the target is unsigned.
4804 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
4805 and then Is_Unsigned_Type (Target_Base_Type));
4807 -- If the source is signed and the target is unsigned, then we
4808 -- know that the target is not shorter than the source (otherwise
4809 -- the target base type would be in the source base type range).
4811 -- In other words, the unsigned type is either the same size as
4812 -- the target, or it is larger. It cannot be smaller.
4814 -- Clearly we have an error if the source value is negative since
4815 -- no unsigned type can have negative values. If the source type
4816 -- is non-negative, then the check can be done using the target
4819 -- Tnn : constant Target_Base_Type (N) := Target_Type;
4821 -- [constraint_error
4822 -- when N < 0 or else Tnn not in Target_Type];
4824 -- We turn off all checks for the conversion of N to the target
4825 -- base type, since we generate the explicit check to ensure that
4826 -- the value is non-negative
4829 Tnn : constant Entity_Id :=
4830 Make_Defining_Identifier (Loc,
4831 Chars => New_Internal_Name ('T'));
4834 Insert_Actions (N, New_List (
4835 Make_Object_Declaration (Loc,
4836 Defining_Identifier => Tnn,
4837 Object_Definition =>
4838 New_Occurrence_Of (Target_Base_Type, Loc),
4839 Constant_Present => True,
4841 Make_Unchecked_Type_Conversion (Loc,
4843 New_Occurrence_Of (Target_Base_Type, Loc),
4844 Expression => Duplicate_Subexpr (N))),
4846 Make_Raise_Constraint_Error (Loc,
4851 Left_Opnd => Duplicate_Subexpr (N),
4852 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4856 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4858 New_Occurrence_Of (Target_Type, Loc))),
4861 Suppress => All_Checks);
4863 -- Set the Etype explicitly, because Insert_Actions may have
4864 -- placed the declaration in the freeze list for an enclosing
4865 -- construct, and thus it is not analyzed yet.
4867 Set_Etype (Tnn, Target_Base_Type);
4868 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4872 end Generate_Range_Check;
4878 function Get_Check_Id (N : Name_Id) return Check_Id is
4880 -- For standard check name, we can do a direct computation
4882 if N in First_Check_Name .. Last_Check_Name then
4883 return Check_Id (N - (First_Check_Name - 1));
4885 -- For non-standard names added by pragma Check_Name, search table
4888 for J in All_Checks + 1 .. Check_Names.Last loop
4889 if Check_Names.Table (J) = N then
4895 -- No matching name found
4900 ---------------------
4901 -- Get_Discriminal --
4902 ---------------------
4904 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
4905 Loc : constant Source_Ptr := Sloc (E);
4910 -- The bound can be a bona fide parameter of a protected operation,
4911 -- rather than a prival encoded as an in-parameter.
4913 if No (Discriminal_Link (Entity (Bound))) then
4917 -- Climb the scope stack looking for an enclosing protected type. If
4918 -- we run out of scopes, return the bound itself.
4921 while Present (Sc) loop
4922 if Sc = Standard_Standard then
4925 elsif Ekind (Sc) = E_Protected_Type then
4932 D := First_Discriminant (Sc);
4933 while Present (D) loop
4934 if Chars (D) = Chars (Bound) then
4935 return New_Occurrence_Of (Discriminal (D), Loc);
4938 Next_Discriminant (D);
4942 end Get_Discriminal;
4944 ----------------------
4945 -- Get_Range_Checks --
4946 ----------------------
4948 function Get_Range_Checks
4950 Target_Typ : Entity_Id;
4951 Source_Typ : Entity_Id := Empty;
4952 Warn_Node : Node_Id := Empty) return Check_Result
4955 return Selected_Range_Checks
4956 (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
4957 end Get_Range_Checks;
4963 function Guard_Access
4966 Ck_Node : Node_Id) return Node_Id
4969 if Nkind (Cond) = N_Or_Else then
4970 Set_Paren_Count (Cond, 1);
4973 if Nkind (Ck_Node) = N_Allocator then
4980 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
4981 Right_Opnd => Make_Null (Loc)),
4982 Right_Opnd => Cond);
4986 -----------------------------
4987 -- Index_Checks_Suppressed --
4988 -----------------------------
4990 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
4992 if Present (E) and then Checks_May_Be_Suppressed (E) then
4993 return Is_Check_Suppressed (E, Index_Check);
4995 return Scope_Suppress (Index_Check);
4997 end Index_Checks_Suppressed;
5003 procedure Initialize is
5005 for J in Determine_Range_Cache_N'Range loop
5006 Determine_Range_Cache_N (J) := Empty;
5011 for J in Int range 1 .. All_Checks loop
5012 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
5016 -------------------------
5017 -- Insert_Range_Checks --
5018 -------------------------
5020 procedure Insert_Range_Checks
5021 (Checks : Check_Result;
5023 Suppress_Typ : Entity_Id;
5024 Static_Sloc : Source_Ptr := No_Location;
5025 Flag_Node : Node_Id := Empty;
5026 Do_Before : Boolean := False)
5028 Internal_Flag_Node : Node_Id := Flag_Node;
5029 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
5031 Check_Node : Node_Id;
5032 Checks_On : constant Boolean :=
5033 (not Index_Checks_Suppressed (Suppress_Typ))
5035 (not Range_Checks_Suppressed (Suppress_Typ));
5038 -- For now we just return if Checks_On is false, however this should be
5039 -- enhanced to check for an always True value in the condition and to
5040 -- generate a compilation warning???
5042 if not Expander_Active or else not Checks_On then
5046 if Static_Sloc = No_Location then
5047 Internal_Static_Sloc := Sloc (Node);
5050 if No (Flag_Node) then
5051 Internal_Flag_Node := Node;
5054 for J in 1 .. 2 loop
5055 exit when No (Checks (J));
5057 if Nkind (Checks (J)) = N_Raise_Constraint_Error
5058 and then Present (Condition (Checks (J)))
5060 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
5061 Check_Node := Checks (J);
5062 Mark_Rewrite_Insertion (Check_Node);
5065 Insert_Before_And_Analyze (Node, Check_Node);
5067 Insert_After_And_Analyze (Node, Check_Node);
5070 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
5075 Make_Raise_Constraint_Error (Internal_Static_Sloc,
5076 Reason => CE_Range_Check_Failed);
5077 Mark_Rewrite_Insertion (Check_Node);
5080 Insert_Before_And_Analyze (Node, Check_Node);
5082 Insert_After_And_Analyze (Node, Check_Node);
5086 end Insert_Range_Checks;
5088 ------------------------
5089 -- Insert_Valid_Check --
5090 ------------------------
5092 procedure Insert_Valid_Check (Expr : Node_Id) is
5093 Loc : constant Source_Ptr := Sloc (Expr);
5097 -- Do not insert if checks off, or if not checking validity or
5098 -- if expression is known to be valid
5100 if not Validity_Checks_On
5101 or else Range_Or_Validity_Checks_Suppressed (Expr)
5102 or else Expr_Known_Valid (Expr)
5107 -- If we have a checked conversion, then validity check applies to
5108 -- the expression inside the conversion, not the result, since if
5109 -- the expression inside is valid, then so is the conversion result.
5112 while Nkind (Exp) = N_Type_Conversion loop
5113 Exp := Expression (Exp);
5116 -- We are about to insert the validity check for Exp. We save and
5117 -- reset the Do_Range_Check flag over this validity check, and then
5118 -- put it back for the final original reference (Exp may be rewritten).
5121 DRC : constant Boolean := Do_Range_Check (Exp);
5124 Set_Do_Range_Check (Exp, False);
5126 -- Force evaluation to avoid multiple reads for atomic/volatile
5128 if Is_Entity_Name (Exp)
5129 and then Is_Volatile (Entity (Exp))
5131 Force_Evaluation (Exp, Name_Req => True);
5134 -- Insert the validity check. Note that we do this with validity
5135 -- checks turned off, to avoid recursion, we do not want validity
5136 -- checks on the validity checking code itself!
5140 Make_Raise_Constraint_Error (Loc,
5144 Make_Attribute_Reference (Loc,
5146 Duplicate_Subexpr_No_Checks (Exp, Name_Req => True),
5147 Attribute_Name => Name_Valid)),
5148 Reason => CE_Invalid_Data),
5149 Suppress => Validity_Check);
5151 -- If the expression is a a reference to an element of a bit-packed
5152 -- array, then it is rewritten as a renaming declaration. If the
5153 -- expression is an actual in a call, it has not been expanded,
5154 -- waiting for the proper point at which to do it. The same happens
5155 -- with renamings, so that we have to force the expansion now. This
5156 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
5159 if Is_Entity_Name (Exp)
5160 and then Nkind (Parent (Entity (Exp))) =
5161 N_Object_Renaming_Declaration
5164 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
5166 if Nkind (Old_Exp) = N_Indexed_Component
5167 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
5169 Expand_Packed_Element_Reference (Old_Exp);
5174 -- Put back the Do_Range_Check flag on the resulting (possibly
5175 -- rewritten) expression.
5177 -- Note: it might be thought that a validity check is not required
5178 -- when a range check is present, but that's not the case, because
5179 -- the back end is allowed to assume for the range check that the
5180 -- operand is within its declared range (an assumption that validity
5181 -- checking is all about NOT assuming!)
5183 -- Note: no need to worry about Possible_Local_Raise here, it will
5184 -- already have been called if original node has Do_Range_Check set.
5186 Set_Do_Range_Check (Exp, DRC);
5188 end Insert_Valid_Check;
5190 ----------------------------------
5191 -- Install_Null_Excluding_Check --
5192 ----------------------------------
5194 procedure Install_Null_Excluding_Check (N : Node_Id) is
5195 Loc : constant Source_Ptr := Sloc (N);
5196 Typ : constant Entity_Id := Etype (N);
5198 function Safe_To_Capture_In_Parameter_Value return Boolean;
5199 -- Determines if it is safe to capture Known_Non_Null status for an
5200 -- the entity referenced by node N. The caller ensures that N is indeed
5201 -- an entity name. It is safe to capture the non-null status for an IN
5202 -- parameter when the reference occurs within a declaration that is sure
5203 -- to be executed as part of the declarative region.
5205 procedure Mark_Non_Null;
5206 -- After installation of check, if the node in question is an entity
5207 -- name, then mark this entity as non-null if possible.
5209 function Safe_To_Capture_In_Parameter_Value return Boolean is
5210 E : constant Entity_Id := Entity (N);
5211 S : constant Entity_Id := Current_Scope;
5215 if Ekind (E) /= E_In_Parameter then
5219 -- Two initial context checks. We must be inside a subprogram body
5220 -- with declarations and reference must not appear in nested scopes.
5222 if (Ekind (S) /= E_Function and then Ekind (S) /= E_Procedure)
5223 or else Scope (E) /= S
5228 S_Par := Parent (Parent (S));
5230 if Nkind (S_Par) /= N_Subprogram_Body
5231 or else No (Declarations (S_Par))
5241 -- Retrieve the declaration node of N (if any). Note that N
5242 -- may be a part of a complex initialization expression.
5246 while Present (P) loop
5248 -- If we have a short circuit form, and we are within the right
5249 -- hand expression, we return false, since the right hand side
5250 -- is not guaranteed to be elaborated.
5252 if Nkind (P) in N_Short_Circuit
5253 and then N = Right_Opnd (P)
5258 -- Similarly, if we are in a conditional expression and not
5259 -- part of the condition, then we return False, since neither
5260 -- the THEN or ELSE expressions will always be elaborated.
5262 if Nkind (P) = N_Conditional_Expression
5263 and then N /= First (Expressions (P))
5268 -- While traversing the parent chain, we find that N
5269 -- belongs to a statement, thus it may never appear in
5270 -- a declarative region.
5272 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
5273 or else Nkind (P) = N_Procedure_Call_Statement
5278 -- If we are at a declaration, record it and exit
5280 if Nkind (P) in N_Declaration
5281 and then Nkind (P) not in N_Subprogram_Specification
5294 return List_Containing (N_Decl) = Declarations (S_Par);
5296 end Safe_To_Capture_In_Parameter_Value;
5302 procedure Mark_Non_Null is
5304 -- Only case of interest is if node N is an entity name
5306 if Is_Entity_Name (N) then
5308 -- For sure, we want to clear an indication that this is known to
5309 -- be null, since if we get past this check, it definitely is not!
5311 Set_Is_Known_Null (Entity (N), False);
5313 -- We can mark the entity as known to be non-null if either it is
5314 -- safe to capture the value, or in the case of an IN parameter,
5315 -- which is a constant, if the check we just installed is in the
5316 -- declarative region of the subprogram body. In this latter case,
5317 -- a check is decisive for the rest of the body if the expression
5318 -- is sure to be elaborated, since we know we have to elaborate
5319 -- all declarations before executing the body.
5321 -- Couldn't this always be part of Safe_To_Capture_Value ???
5323 if Safe_To_Capture_Value (N, Entity (N))
5324 or else Safe_To_Capture_In_Parameter_Value
5326 Set_Is_Known_Non_Null (Entity (N));
5331 -- Start of processing for Install_Null_Excluding_Check
5334 pragma Assert (Is_Access_Type (Typ));
5336 -- No check inside a generic (why not???)
5338 if Inside_A_Generic then
5342 -- No check needed if known to be non-null
5344 if Known_Non_Null (N) then
5348 -- If known to be null, here is where we generate a compile time check
5350 if Known_Null (N) then
5352 -- Avoid generating warning message inside init procs
5354 if not Inside_Init_Proc then
5355 Apply_Compile_Time_Constraint_Error
5357 "null value not allowed here?",
5358 CE_Access_Check_Failed);
5361 Make_Raise_Constraint_Error (Loc,
5362 Reason => CE_Access_Check_Failed));
5369 -- If entity is never assigned, for sure a warning is appropriate
5371 if Is_Entity_Name (N) then
5372 Check_Unset_Reference (N);
5375 -- No check needed if checks are suppressed on the range. Note that we
5376 -- don't set Is_Known_Non_Null in this case (we could legitimately do
5377 -- so, since the program is erroneous, but we don't like to casually
5378 -- propagate such conclusions from erroneosity).
5380 if Access_Checks_Suppressed (Typ) then
5384 -- No check needed for access to concurrent record types generated by
5385 -- the expander. This is not just an optimization (though it does indeed
5386 -- remove junk checks). It also avoids generation of junk warnings.
5388 if Nkind (N) in N_Has_Chars
5389 and then Chars (N) = Name_uObject
5390 and then Is_Concurrent_Record_Type
5391 (Directly_Designated_Type (Etype (N)))
5396 -- Otherwise install access check
5399 Make_Raise_Constraint_Error (Loc,
5402 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
5403 Right_Opnd => Make_Null (Loc)),
5404 Reason => CE_Access_Check_Failed));
5407 end Install_Null_Excluding_Check;
5409 --------------------------
5410 -- Install_Static_Check --
5411 --------------------------
5413 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
5414 Stat : constant Boolean := Is_Static_Expression (R_Cno);
5415 Typ : constant Entity_Id := Etype (R_Cno);
5419 Make_Raise_Constraint_Error (Loc,
5420 Reason => CE_Range_Check_Failed));
5421 Set_Analyzed (R_Cno);
5422 Set_Etype (R_Cno, Typ);
5423 Set_Raises_Constraint_Error (R_Cno);
5424 Set_Is_Static_Expression (R_Cno, Stat);
5426 -- Now deal with possible local raise handling
5428 Possible_Local_Raise (R_Cno, Standard_Constraint_Error);
5429 end Install_Static_Check;
5431 ---------------------
5432 -- Kill_All_Checks --
5433 ---------------------
5435 procedure Kill_All_Checks is
5437 if Debug_Flag_CC then
5438 w ("Kill_All_Checks");
5441 -- We reset the number of saved checks to zero, and also modify all
5442 -- stack entries for statement ranges to indicate that the number of
5443 -- checks at each level is now zero.
5445 Num_Saved_Checks := 0;
5447 -- Note: the Int'Min here avoids any possibility of J being out of
5448 -- range when called from e.g. Conditional_Statements_Begin.
5450 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
5451 Saved_Checks_Stack (J) := 0;
5453 end Kill_All_Checks;
5459 procedure Kill_Checks (V : Entity_Id) is
5461 if Debug_Flag_CC then
5462 w ("Kill_Checks for entity", Int (V));
5465 for J in 1 .. Num_Saved_Checks loop
5466 if Saved_Checks (J).Entity = V then
5467 if Debug_Flag_CC then
5468 w (" Checks killed for saved check ", J);
5471 Saved_Checks (J).Killed := True;
5476 ------------------------------
5477 -- Length_Checks_Suppressed --
5478 ------------------------------
5480 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
5482 if Present (E) and then Checks_May_Be_Suppressed (E) then
5483 return Is_Check_Suppressed (E, Length_Check);
5485 return Scope_Suppress (Length_Check);
5487 end Length_Checks_Suppressed;
5489 --------------------------------
5490 -- Overflow_Checks_Suppressed --
5491 --------------------------------
5493 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
5495 if Present (E) and then Checks_May_Be_Suppressed (E) then
5496 return Is_Check_Suppressed (E, Overflow_Check);
5498 return Scope_Suppress (Overflow_Check);
5500 end Overflow_Checks_Suppressed;
5502 -----------------------------
5503 -- Range_Checks_Suppressed --
5504 -----------------------------
5506 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
5510 -- Note: for now we always suppress range checks on Vax float types,
5511 -- since Gigi does not know how to generate these checks.
5513 if Vax_Float (E) then
5515 elsif Kill_Range_Checks (E) then
5517 elsif Checks_May_Be_Suppressed (E) then
5518 return Is_Check_Suppressed (E, Range_Check);
5522 return Scope_Suppress (Range_Check);
5523 end Range_Checks_Suppressed;
5525 -----------------------------------------
5526 -- Range_Or_Validity_Checks_Suppressed --
5527 -----------------------------------------
5529 -- Note: the coding would be simpler here if we simply made appropriate
5530 -- calls to Range/Validity_Checks_Suppressed, but that would result in
5531 -- duplicated checks which we prefer to avoid.
5533 function Range_Or_Validity_Checks_Suppressed
5534 (Expr : Node_Id) return Boolean
5537 -- Immediate return if scope checks suppressed for either check
5539 if Scope_Suppress (Range_Check) or Scope_Suppress (Validity_Check) then
5543 -- If no expression, that's odd, decide that checks are suppressed,
5544 -- since we don't want anyone trying to do checks in this case, which
5545 -- is most likely the result of some other error.
5551 -- Expression is present, so perform suppress checks on type
5554 Typ : constant Entity_Id := Etype (Expr);
5556 if Vax_Float (Typ) then
5558 elsif Checks_May_Be_Suppressed (Typ)
5559 and then (Is_Check_Suppressed (Typ, Range_Check)
5561 Is_Check_Suppressed (Typ, Validity_Check))
5567 -- If expression is an entity name, perform checks on this entity
5569 if Is_Entity_Name (Expr) then
5571 Ent : constant Entity_Id := Entity (Expr);
5573 if Checks_May_Be_Suppressed (Ent) then
5574 return Is_Check_Suppressed (Ent, Range_Check)
5575 or else Is_Check_Suppressed (Ent, Validity_Check);
5580 -- If we fall through, no checks suppressed
5583 end Range_Or_Validity_Checks_Suppressed;
5589 procedure Remove_Checks (Expr : Node_Id) is
5590 function Process (N : Node_Id) return Traverse_Result;
5591 -- Process a single node during the traversal
5593 procedure Traverse is new Traverse_Proc (Process);
5594 -- The traversal procedure itself
5600 function Process (N : Node_Id) return Traverse_Result is
5602 if Nkind (N) not in N_Subexpr then
5606 Set_Do_Range_Check (N, False);
5610 Traverse (Left_Opnd (N));
5613 when N_Attribute_Reference =>
5614 Set_Do_Overflow_Check (N, False);
5616 when N_Function_Call =>
5617 Set_Do_Tag_Check (N, False);
5620 Set_Do_Overflow_Check (N, False);
5624 Set_Do_Division_Check (N, False);
5627 Set_Do_Length_Check (N, False);
5630 Set_Do_Division_Check (N, False);
5633 Set_Do_Length_Check (N, False);
5636 Set_Do_Division_Check (N, False);
5639 Set_Do_Length_Check (N, False);
5646 Traverse (Left_Opnd (N));
5649 when N_Selected_Component =>
5650 Set_Do_Discriminant_Check (N, False);
5652 when N_Type_Conversion =>
5653 Set_Do_Length_Check (N, False);
5654 Set_Do_Tag_Check (N, False);
5655 Set_Do_Overflow_Check (N, False);
5664 -- Start of processing for Remove_Checks
5670 ----------------------------
5671 -- Selected_Length_Checks --
5672 ----------------------------
5674 function Selected_Length_Checks
5676 Target_Typ : Entity_Id;
5677 Source_Typ : Entity_Id;
5678 Warn_Node : Node_Id) return Check_Result
5680 Loc : constant Source_Ptr := Sloc (Ck_Node);
5683 Expr_Actual : Node_Id;
5685 Cond : Node_Id := Empty;
5686 Do_Access : Boolean := False;
5687 Wnode : Node_Id := Warn_Node;
5688 Ret_Result : Check_Result := (Empty, Empty);
5689 Num_Checks : Natural := 0;
5691 procedure Add_Check (N : Node_Id);
5692 -- Adds the action given to Ret_Result if N is non-Empty
5694 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
5695 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
5696 -- Comments required ???
5698 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
5699 -- True for equal literals and for nodes that denote the same constant
5700 -- entity, even if its value is not a static constant. This includes the
5701 -- case of a discriminal reference within an init proc. Removes some
5702 -- obviously superfluous checks.
5704 function Length_E_Cond
5705 (Exptyp : Entity_Id;
5707 Indx : Nat) return Node_Id;
5708 -- Returns expression to compute:
5709 -- Typ'Length /= Exptyp'Length
5711 function Length_N_Cond
5714 Indx : Nat) return Node_Id;
5715 -- Returns expression to compute:
5716 -- Typ'Length /= Expr'Length
5722 procedure Add_Check (N : Node_Id) is
5726 -- For now, ignore attempt to place more than 2 checks ???
5728 if Num_Checks = 2 then
5732 pragma Assert (Num_Checks <= 1);
5733 Num_Checks := Num_Checks + 1;
5734 Ret_Result (Num_Checks) := N;
5742 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
5743 SE : constant Entity_Id := Scope (E);
5745 E1 : Entity_Id := E;
5748 if Ekind (Scope (E)) = E_Record_Type
5749 and then Has_Discriminants (Scope (E))
5751 N := Build_Discriminal_Subtype_Of_Component (E);
5754 Insert_Action (Ck_Node, N);
5755 E1 := Defining_Identifier (N);
5759 if Ekind (E1) = E_String_Literal_Subtype then
5761 Make_Integer_Literal (Loc,
5762 Intval => String_Literal_Length (E1));
5764 elsif SE /= Standard_Standard
5765 and then Ekind (Scope (SE)) = E_Protected_Type
5766 and then Has_Discriminants (Scope (SE))
5767 and then Has_Completion (Scope (SE))
5768 and then not Inside_Init_Proc
5770 -- If the type whose length is needed is a private component
5771 -- constrained by a discriminant, we must expand the 'Length
5772 -- attribute into an explicit computation, using the discriminal
5773 -- of the current protected operation. This is because the actual
5774 -- type of the prival is constructed after the protected opera-
5775 -- tion has been fully expanded.
5778 Indx_Type : Node_Id;
5781 Do_Expand : Boolean := False;
5784 Indx_Type := First_Index (E);
5786 for J in 1 .. Indx - 1 loop
5787 Next_Index (Indx_Type);
5790 Get_Index_Bounds (Indx_Type, Lo, Hi);
5792 if Nkind (Lo) = N_Identifier
5793 and then Ekind (Entity (Lo)) = E_In_Parameter
5795 Lo := Get_Discriminal (E, Lo);
5799 if Nkind (Hi) = N_Identifier
5800 and then Ekind (Entity (Hi)) = E_In_Parameter
5802 Hi := Get_Discriminal (E, Hi);
5807 if not Is_Entity_Name (Lo) then
5808 Lo := Duplicate_Subexpr_No_Checks (Lo);
5811 if not Is_Entity_Name (Hi) then
5812 Lo := Duplicate_Subexpr_No_Checks (Hi);
5818 Make_Op_Subtract (Loc,
5822 Right_Opnd => Make_Integer_Literal (Loc, 1));
5827 Make_Attribute_Reference (Loc,
5828 Attribute_Name => Name_Length,
5830 New_Occurrence_Of (E1, Loc));
5833 Set_Expressions (N, New_List (
5834 Make_Integer_Literal (Loc, Indx)));
5843 Make_Attribute_Reference (Loc,
5844 Attribute_Name => Name_Length,
5846 New_Occurrence_Of (E1, Loc));
5849 Set_Expressions (N, New_List (
5850 Make_Integer_Literal (Loc, Indx)));
5861 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
5864 Make_Attribute_Reference (Loc,
5865 Attribute_Name => Name_Length,
5867 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
5868 Expressions => New_List (
5869 Make_Integer_Literal (Loc, Indx)));
5876 function Length_E_Cond
5877 (Exptyp : Entity_Id;
5879 Indx : Nat) return Node_Id
5884 Left_Opnd => Get_E_Length (Typ, Indx),
5885 Right_Opnd => Get_E_Length (Exptyp, Indx));
5892 function Length_N_Cond
5895 Indx : Nat) return Node_Id
5900 Left_Opnd => Get_E_Length (Typ, Indx),
5901 Right_Opnd => Get_N_Length (Expr, Indx));
5908 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
5911 (Nkind (L) = N_Integer_Literal
5912 and then Nkind (R) = N_Integer_Literal
5913 and then Intval (L) = Intval (R))
5917 and then Ekind (Entity (L)) = E_Constant
5918 and then ((Is_Entity_Name (R)
5919 and then Entity (L) = Entity (R))
5921 (Nkind (R) = N_Type_Conversion
5922 and then Is_Entity_Name (Expression (R))
5923 and then Entity (L) = Entity (Expression (R)))))
5927 and then Ekind (Entity (R)) = E_Constant
5928 and then Nkind (L) = N_Type_Conversion
5929 and then Is_Entity_Name (Expression (L))
5930 and then Entity (R) = Entity (Expression (L)))
5934 and then Is_Entity_Name (R)
5935 and then Entity (L) = Entity (R)
5936 and then Ekind (Entity (L)) = E_In_Parameter
5937 and then Inside_Init_Proc);
5940 -- Start of processing for Selected_Length_Checks
5943 if not Expander_Active then
5947 if Target_Typ = Any_Type
5948 or else Target_Typ = Any_Composite
5949 or else Raises_Constraint_Error (Ck_Node)
5958 T_Typ := Target_Typ;
5960 if No (Source_Typ) then
5961 S_Typ := Etype (Ck_Node);
5963 S_Typ := Source_Typ;
5966 if S_Typ = Any_Type or else S_Typ = Any_Composite then
5970 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
5971 S_Typ := Designated_Type (S_Typ);
5972 T_Typ := Designated_Type (T_Typ);
5975 -- A simple optimization for the null case
5977 if Known_Null (Ck_Node) then
5982 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
5983 if Is_Constrained (T_Typ) then
5985 -- The checking code to be generated will freeze the
5986 -- corresponding array type. However, we must freeze the
5987 -- type now, so that the freeze node does not appear within
5988 -- the generated condional expression, but ahead of it.
5990 Freeze_Before (Ck_Node, T_Typ);
5992 Expr_Actual := Get_Referenced_Object (Ck_Node);
5993 Exptyp := Get_Actual_Subtype (Ck_Node);
5995 if Is_Access_Type (Exptyp) then
5996 Exptyp := Designated_Type (Exptyp);
5999 -- String_Literal case. This needs to be handled specially be-
6000 -- cause no index types are available for string literals. The
6001 -- condition is simply:
6003 -- T_Typ'Length = string-literal-length
6005 if Nkind (Expr_Actual) = N_String_Literal
6006 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
6010 Left_Opnd => Get_E_Length (T_Typ, 1),
6012 Make_Integer_Literal (Loc,
6014 String_Literal_Length (Etype (Expr_Actual))));
6016 -- General array case. Here we have a usable actual subtype for
6017 -- the expression, and the condition is built from the two types
6020 -- T_Typ'Length /= Exptyp'Length or else
6021 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
6022 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
6025 elsif Is_Constrained (Exptyp) then
6027 Ndims : constant Nat := Number_Dimensions (T_Typ);
6040 -- At the library level, we need to ensure that the type of
6041 -- the object is elaborated before the check itself is
6042 -- emitted. This is only done if the object is in the
6043 -- current compilation unit, otherwise the type is frozen
6044 -- and elaborated in its unit.
6046 if Is_Itype (Exptyp)
6048 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
6050 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
6051 and then In_Open_Scopes (Scope (Exptyp))
6053 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
6054 Set_Itype (Ref_Node, Exptyp);
6055 Insert_Action (Ck_Node, Ref_Node);
6058 L_Index := First_Index (T_Typ);
6059 R_Index := First_Index (Exptyp);
6061 for Indx in 1 .. Ndims loop
6062 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6064 Nkind (R_Index) = N_Raise_Constraint_Error)
6066 Get_Index_Bounds (L_Index, L_Low, L_High);
6067 Get_Index_Bounds (R_Index, R_Low, R_High);
6069 -- Deal with compile time length check. Note that we
6070 -- skip this in the access case, because the access
6071 -- value may be null, so we cannot know statically.
6074 and then Compile_Time_Known_Value (L_Low)
6075 and then Compile_Time_Known_Value (L_High)
6076 and then Compile_Time_Known_Value (R_Low)
6077 and then Compile_Time_Known_Value (R_High)
6079 if Expr_Value (L_High) >= Expr_Value (L_Low) then
6080 L_Length := Expr_Value (L_High) -
6081 Expr_Value (L_Low) + 1;
6083 L_Length := UI_From_Int (0);
6086 if Expr_Value (R_High) >= Expr_Value (R_Low) then
6087 R_Length := Expr_Value (R_High) -
6088 Expr_Value (R_Low) + 1;
6090 R_Length := UI_From_Int (0);
6093 if L_Length > R_Length then
6095 (Compile_Time_Constraint_Error
6096 (Wnode, "too few elements for}?", T_Typ));
6098 elsif L_Length < R_Length then
6100 (Compile_Time_Constraint_Error
6101 (Wnode, "too many elements for}?", T_Typ));
6104 -- The comparison for an individual index subtype
6105 -- is omitted if the corresponding index subtypes
6106 -- statically match, since the result is known to
6107 -- be true. Note that this test is worth while even
6108 -- though we do static evaluation, because non-static
6109 -- subtypes can statically match.
6112 Subtypes_Statically_Match
6113 (Etype (L_Index), Etype (R_Index))
6116 (Same_Bounds (L_Low, R_Low)
6117 and then Same_Bounds (L_High, R_High))
6120 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
6129 -- Handle cases where we do not get a usable actual subtype that
6130 -- is constrained. This happens for example in the function call
6131 -- and explicit dereference cases. In these cases, we have to get
6132 -- the length or range from the expression itself, making sure we
6133 -- do not evaluate it more than once.
6135 -- Here Ck_Node is the original expression, or more properly the
6136 -- result of applying Duplicate_Expr to the original tree, forcing
6137 -- the result to be a name.
6141 Ndims : constant Nat := Number_Dimensions (T_Typ);
6144 -- Build the condition for the explicit dereference case
6146 for Indx in 1 .. Ndims loop
6148 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
6155 -- Construct the test and insert into the tree
6157 if Present (Cond) then
6159 Cond := Guard_Access (Cond, Loc, Ck_Node);
6163 (Make_Raise_Constraint_Error (Loc,
6165 Reason => CE_Length_Check_Failed));
6169 end Selected_Length_Checks;
6171 ---------------------------
6172 -- Selected_Range_Checks --
6173 ---------------------------
6175 function Selected_Range_Checks
6177 Target_Typ : Entity_Id;
6178 Source_Typ : Entity_Id;
6179 Warn_Node : Node_Id) return Check_Result
6181 Loc : constant Source_Ptr := Sloc (Ck_Node);
6184 Expr_Actual : Node_Id;
6186 Cond : Node_Id := Empty;
6187 Do_Access : Boolean := False;
6188 Wnode : Node_Id := Warn_Node;
6189 Ret_Result : Check_Result := (Empty, Empty);
6190 Num_Checks : Integer := 0;
6192 procedure Add_Check (N : Node_Id);
6193 -- Adds the action given to Ret_Result if N is non-Empty
6195 function Discrete_Range_Cond
6197 Typ : Entity_Id) return Node_Id;
6198 -- Returns expression to compute:
6199 -- Low_Bound (Expr) < Typ'First
6201 -- High_Bound (Expr) > Typ'Last
6203 function Discrete_Expr_Cond
6205 Typ : Entity_Id) return Node_Id;
6206 -- Returns expression to compute:
6211 function Get_E_First_Or_Last
6214 Nam : Name_Id) return Node_Id;
6215 -- Returns expression to compute:
6216 -- E'First or E'Last
6218 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
6219 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
6220 -- Returns expression to compute:
6221 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
6223 function Range_E_Cond
6224 (Exptyp : Entity_Id;
6228 -- Returns expression to compute:
6229 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
6231 function Range_Equal_E_Cond
6232 (Exptyp : Entity_Id;
6234 Indx : Nat) return Node_Id;
6235 -- Returns expression to compute:
6236 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
6238 function Range_N_Cond
6241 Indx : Nat) return Node_Id;
6242 -- Return expression to compute:
6243 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
6249 procedure Add_Check (N : Node_Id) is
6253 -- For now, ignore attempt to place more than 2 checks ???
6255 if Num_Checks = 2 then
6259 pragma Assert (Num_Checks <= 1);
6260 Num_Checks := Num_Checks + 1;
6261 Ret_Result (Num_Checks) := N;
6265 -------------------------
6266 -- Discrete_Expr_Cond --
6267 -------------------------
6269 function Discrete_Expr_Cond
6271 Typ : Entity_Id) return Node_Id
6279 Convert_To (Base_Type (Typ),
6280 Duplicate_Subexpr_No_Checks (Expr)),
6282 Convert_To (Base_Type (Typ),
6283 Get_E_First_Or_Last (Typ, 0, Name_First))),
6288 Convert_To (Base_Type (Typ),
6289 Duplicate_Subexpr_No_Checks (Expr)),
6293 Get_E_First_Or_Last (Typ, 0, Name_Last))));
6294 end Discrete_Expr_Cond;
6296 -------------------------
6297 -- Discrete_Range_Cond --
6298 -------------------------
6300 function Discrete_Range_Cond
6302 Typ : Entity_Id) return Node_Id
6304 LB : Node_Id := Low_Bound (Expr);
6305 HB : Node_Id := High_Bound (Expr);
6307 Left_Opnd : Node_Id;
6308 Right_Opnd : Node_Id;
6311 if Nkind (LB) = N_Identifier
6312 and then Ekind (Entity (LB)) = E_Discriminant
6314 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6317 if Nkind (HB) = N_Identifier
6318 and then Ekind (Entity (HB)) = E_Discriminant
6320 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6327 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
6331 (Base_Type (Typ), Get_E_First_Or_Last (Typ, 0, Name_First)));
6333 if Base_Type (Typ) = Typ then
6336 elsif Compile_Time_Known_Value (High_Bound (Scalar_Range (Typ)))
6338 Compile_Time_Known_Value (High_Bound (Scalar_Range
6341 if Is_Floating_Point_Type (Typ) then
6342 if Expr_Value_R (High_Bound (Scalar_Range (Typ))) =
6343 Expr_Value_R (High_Bound (Scalar_Range (Base_Type (Typ))))
6349 if Expr_Value (High_Bound (Scalar_Range (Typ))) =
6350 Expr_Value (High_Bound (Scalar_Range (Base_Type (Typ))))
6361 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
6366 Get_E_First_Or_Last (Typ, 0, Name_Last)));
6368 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
6369 end Discrete_Range_Cond;
6371 -------------------------
6372 -- Get_E_First_Or_Last --
6373 -------------------------
6375 function Get_E_First_Or_Last
6378 Nam : Name_Id) return Node_Id
6386 if Is_Array_Type (E) then
6387 N := First_Index (E);
6389 for J in 2 .. Indx loop
6394 N := Scalar_Range (E);
6397 if Nkind (N) = N_Subtype_Indication then
6398 LB := Low_Bound (Range_Expression (Constraint (N)));
6399 HB := High_Bound (Range_Expression (Constraint (N)));
6401 elsif Is_Entity_Name (N) then
6402 LB := Type_Low_Bound (Etype (N));
6403 HB := Type_High_Bound (Etype (N));
6406 LB := Low_Bound (N);
6407 HB := High_Bound (N);
6410 if Nam = Name_First then
6416 if Nkind (Bound) = N_Identifier
6417 and then Ekind (Entity (Bound)) = E_Discriminant
6419 -- If this is a task discriminant, and we are the body, we must
6420 -- retrieve the corresponding body discriminal. This is another
6421 -- consequence of the early creation of discriminals, and the
6422 -- need to generate constraint checks before their declarations
6423 -- are made visible.
6425 if Is_Concurrent_Record_Type (Scope (Entity (Bound))) then
6427 Tsk : constant Entity_Id :=
6428 Corresponding_Concurrent_Type
6429 (Scope (Entity (Bound)));
6433 if In_Open_Scopes (Tsk)
6434 and then Has_Completion (Tsk)
6436 -- Find discriminant of original task, and use its
6437 -- current discriminal, which is the renaming within
6440 Disc := First_Discriminant (Tsk);
6441 while Present (Disc) loop
6442 if Chars (Disc) = Chars (Entity (Bound)) then
6443 Set_Scope (Discriminal (Disc), Tsk);
6444 return New_Occurrence_Of (Discriminal (Disc), Loc);
6447 Next_Discriminant (Disc);
6450 -- That loop should always succeed in finding a matching
6451 -- entry and returning. Fatal error if not.
6453 raise Program_Error;
6457 New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6461 return New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6464 elsif Nkind (Bound) = N_Identifier
6465 and then Ekind (Entity (Bound)) = E_In_Parameter
6466 and then not Inside_Init_Proc
6468 return Get_Discriminal (E, Bound);
6470 elsif Nkind (Bound) = N_Integer_Literal then
6471 return Make_Integer_Literal (Loc, Intval (Bound));
6473 -- Case of a bound rewritten to an N_Raise_Constraint_Error node
6474 -- because it is an out-of-range value. Duplicate_Subexpr cannot be
6475 -- called on this node because an N_Raise_Constraint_Error is not
6476 -- side effect free, and we may not assume that we are in the proper
6477 -- context to remove side effects on it at the point of reference.
6479 elsif Nkind (Bound) = N_Raise_Constraint_Error then
6480 return New_Copy_Tree (Bound);
6483 return Duplicate_Subexpr_No_Checks (Bound);
6485 end Get_E_First_Or_Last;
6491 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
6494 Make_Attribute_Reference (Loc,
6495 Attribute_Name => Name_First,
6497 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6498 Expressions => New_List (
6499 Make_Integer_Literal (Loc, Indx)));
6506 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
6509 Make_Attribute_Reference (Loc,
6510 Attribute_Name => Name_Last,
6512 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6513 Expressions => New_List (
6514 Make_Integer_Literal (Loc, Indx)));
6521 function Range_E_Cond
6522 (Exptyp : Entity_Id;
6524 Indx : Nat) return Node_Id
6531 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6532 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6536 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6537 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6540 ------------------------
6541 -- Range_Equal_E_Cond --
6542 ------------------------
6544 function Range_Equal_E_Cond
6545 (Exptyp : Entity_Id;
6547 Indx : Nat) return Node_Id
6554 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6555 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6558 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6559 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6560 end Range_Equal_E_Cond;
6566 function Range_N_Cond
6569 Indx : Nat) return Node_Id
6576 Left_Opnd => Get_N_First (Expr, Indx),
6577 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6581 Left_Opnd => Get_N_Last (Expr, Indx),
6582 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6585 -- Start of processing for Selected_Range_Checks
6588 if not Expander_Active then
6592 if Target_Typ = Any_Type
6593 or else Target_Typ = Any_Composite
6594 or else Raises_Constraint_Error (Ck_Node)
6603 T_Typ := Target_Typ;
6605 if No (Source_Typ) then
6606 S_Typ := Etype (Ck_Node);
6608 S_Typ := Source_Typ;
6611 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6615 -- The order of evaluating T_Typ before S_Typ seems to be critical
6616 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
6617 -- in, and since Node can be an N_Range node, it might be invalid.
6618 -- Should there be an assert check somewhere for taking the Etype of
6619 -- an N_Range node ???
6621 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6622 S_Typ := Designated_Type (S_Typ);
6623 T_Typ := Designated_Type (T_Typ);
6626 -- A simple optimization for the null case
6628 if Known_Null (Ck_Node) then
6633 -- For an N_Range Node, check for a null range and then if not
6634 -- null generate a range check action.
6636 if Nkind (Ck_Node) = N_Range then
6638 -- There's no point in checking a range against itself
6640 if Ck_Node = Scalar_Range (T_Typ) then
6645 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
6646 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
6647 LB : constant Node_Id := Low_Bound (Ck_Node);
6648 HB : constant Node_Id := High_Bound (Ck_Node);
6649 Null_Range : Boolean;
6651 Out_Of_Range_L : Boolean;
6652 Out_Of_Range_H : Boolean;
6655 -- Check for case where everything is static and we can
6656 -- do the check at compile time. This is skipped if we
6657 -- have an access type, since the access value may be null.
6659 -- ??? This code can be improved since you only need to know
6660 -- that the two respective bounds (LB & T_LB or HB & T_HB)
6661 -- are known at compile time to emit pertinent messages.
6663 if Compile_Time_Known_Value (LB)
6664 and then Compile_Time_Known_Value (HB)
6665 and then Compile_Time_Known_Value (T_LB)
6666 and then Compile_Time_Known_Value (T_HB)
6667 and then not Do_Access
6669 -- Floating-point case
6671 if Is_Floating_Point_Type (S_Typ) then
6672 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
6674 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
6676 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
6679 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
6681 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
6683 -- Fixed or discrete type case
6686 Null_Range := Expr_Value (HB) < Expr_Value (LB);
6688 (Expr_Value (LB) < Expr_Value (T_LB))
6690 (Expr_Value (LB) > Expr_Value (T_HB));
6693 (Expr_Value (HB) > Expr_Value (T_HB))
6695 (Expr_Value (HB) < Expr_Value (T_LB));
6698 if not Null_Range then
6699 if Out_Of_Range_L then
6700 if No (Warn_Node) then
6702 (Compile_Time_Constraint_Error
6703 (Low_Bound (Ck_Node),
6704 "static value out of range of}?", T_Typ));
6708 (Compile_Time_Constraint_Error
6710 "static range out of bounds of}?", T_Typ));
6714 if Out_Of_Range_H then
6715 if No (Warn_Node) then
6717 (Compile_Time_Constraint_Error
6718 (High_Bound (Ck_Node),
6719 "static value out of range of}?", T_Typ));
6723 (Compile_Time_Constraint_Error
6725 "static range out of bounds of}?", T_Typ));
6733 LB : Node_Id := Low_Bound (Ck_Node);
6734 HB : Node_Id := High_Bound (Ck_Node);
6737 -- If either bound is a discriminant and we are within the
6738 -- record declaration, it is a use of the discriminant in a
6739 -- constraint of a component, and nothing can be checked
6740 -- here. The check will be emitted within the init proc.
6741 -- Before then, the discriminal has no real meaning.
6742 -- Similarly, if the entity is a discriminal, there is no
6743 -- check to perform yet.
6745 -- The same holds within a discriminated synchronized type,
6746 -- where the discriminant may constrain a component or an
6749 if Nkind (LB) = N_Identifier
6750 and then Denotes_Discriminant (LB, True)
6752 if Current_Scope = Scope (Entity (LB))
6753 or else Is_Concurrent_Type (Current_Scope)
6754 or else Ekind (Entity (LB)) /= E_Discriminant
6759 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6763 if Nkind (HB) = N_Identifier
6764 and then Denotes_Discriminant (HB, True)
6766 if Current_Scope = Scope (Entity (HB))
6767 or else Is_Concurrent_Type (Current_Scope)
6768 or else Ekind (Entity (HB)) /= E_Discriminant
6773 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6777 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
6778 Set_Paren_Count (Cond, 1);
6784 Left_Opnd => Duplicate_Subexpr_No_Checks (HB),
6785 Right_Opnd => Duplicate_Subexpr_No_Checks (LB)),
6786 Right_Opnd => Cond);
6791 elsif Is_Scalar_Type (S_Typ) then
6793 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
6794 -- except the above simply sets a flag in the node and lets
6795 -- gigi generate the check base on the Etype of the expression.
6796 -- Sometimes, however we want to do a dynamic check against an
6797 -- arbitrary target type, so we do that here.
6799 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
6800 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6802 -- For literals, we can tell if the constraint error will be
6803 -- raised at compile time, so we never need a dynamic check, but
6804 -- if the exception will be raised, then post the usual warning,
6805 -- and replace the literal with a raise constraint error
6806 -- expression. As usual, skip this for access types
6808 elsif Compile_Time_Known_Value (Ck_Node)
6809 and then not Do_Access
6812 LB : constant Node_Id := Type_Low_Bound (T_Typ);
6813 UB : constant Node_Id := Type_High_Bound (T_Typ);
6815 Out_Of_Range : Boolean;
6816 Static_Bounds : constant Boolean :=
6817 Compile_Time_Known_Value (LB)
6818 and Compile_Time_Known_Value (UB);
6821 -- Following range tests should use Sem_Eval routine ???
6823 if Static_Bounds then
6824 if Is_Floating_Point_Type (S_Typ) then
6826 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
6828 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
6830 else -- fixed or discrete type
6832 Expr_Value (Ck_Node) < Expr_Value (LB)
6834 Expr_Value (Ck_Node) > Expr_Value (UB);
6837 -- Bounds of the type are static and the literal is
6838 -- out of range so make a warning message.
6840 if Out_Of_Range then
6841 if No (Warn_Node) then
6843 (Compile_Time_Constraint_Error
6845 "static value out of range of}?", T_Typ));
6849 (Compile_Time_Constraint_Error
6851 "static value out of range of}?", T_Typ));
6856 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6860 -- Here for the case of a non-static expression, we need a runtime
6861 -- check unless the source type range is guaranteed to be in the
6862 -- range of the target type.
6865 if not In_Subrange_Of (S_Typ, T_Typ) then
6866 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6871 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6872 if Is_Constrained (T_Typ) then
6874 Expr_Actual := Get_Referenced_Object (Ck_Node);
6875 Exptyp := Get_Actual_Subtype (Expr_Actual);
6877 if Is_Access_Type (Exptyp) then
6878 Exptyp := Designated_Type (Exptyp);
6881 -- String_Literal case. This needs to be handled specially be-
6882 -- cause no index types are available for string literals. The
6883 -- condition is simply:
6885 -- T_Typ'Length = string-literal-length
6887 if Nkind (Expr_Actual) = N_String_Literal then
6890 -- General array case. Here we have a usable actual subtype for
6891 -- the expression, and the condition is built from the two types
6893 -- T_Typ'First < Exptyp'First or else
6894 -- T_Typ'Last > Exptyp'Last or else
6895 -- T_Typ'First(1) < Exptyp'First(1) or else
6896 -- T_Typ'Last(1) > Exptyp'Last(1) or else
6899 elsif Is_Constrained (Exptyp) then
6901 Ndims : constant Nat := Number_Dimensions (T_Typ);
6907 L_Index := First_Index (T_Typ);
6908 R_Index := First_Index (Exptyp);
6910 for Indx in 1 .. Ndims loop
6911 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6913 Nkind (R_Index) = N_Raise_Constraint_Error)
6915 -- Deal with compile time length check. Note that we
6916 -- skip this in the access case, because the access
6917 -- value may be null, so we cannot know statically.
6920 Subtypes_Statically_Match
6921 (Etype (L_Index), Etype (R_Index))
6923 -- If the target type is constrained then we
6924 -- have to check for exact equality of bounds
6925 -- (required for qualified expressions).
6927 if Is_Constrained (T_Typ) then
6930 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
6933 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
6944 -- Handle cases where we do not get a usable actual subtype that
6945 -- is constrained. This happens for example in the function call
6946 -- and explicit dereference cases. In these cases, we have to get
6947 -- the length or range from the expression itself, making sure we
6948 -- do not evaluate it more than once.
6950 -- Here Ck_Node is the original expression, or more properly the
6951 -- result of applying Duplicate_Expr to the original tree,
6952 -- forcing the result to be a name.
6956 Ndims : constant Nat := Number_Dimensions (T_Typ);
6959 -- Build the condition for the explicit dereference case
6961 for Indx in 1 .. Ndims loop
6963 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
6970 -- For a conversion to an unconstrained array type, generate an
6971 -- Action to check that the bounds of the source value are within
6972 -- the constraints imposed by the target type (RM 4.6(38)). No
6973 -- check is needed for a conversion to an access to unconstrained
6974 -- array type, as 4.6(24.15/2) requires the designated subtypes
6975 -- of the two access types to statically match.
6977 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
6978 and then not Do_Access
6981 Opnd_Index : Node_Id;
6982 Targ_Index : Node_Id;
6983 Opnd_Range : Node_Id;
6986 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
6987 Targ_Index := First_Index (T_Typ);
6988 while Present (Opnd_Index) loop
6990 -- If the index is a range, use its bounds. If it is an
6991 -- entity (as will be the case if it is a named subtype
6992 -- or an itype created for a slice) retrieve its range.
6994 if Is_Entity_Name (Opnd_Index)
6995 and then Is_Type (Entity (Opnd_Index))
6997 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
6999 Opnd_Range := Opnd_Index;
7002 if Nkind (Opnd_Range) = N_Range then
7004 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7005 Assume_Valid => True)
7008 (High_Bound (Opnd_Range), Etype (Targ_Index),
7009 Assume_Valid => True)
7013 -- If null range, no check needed
7016 Compile_Time_Known_Value (High_Bound (Opnd_Range))
7018 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
7020 Expr_Value (High_Bound (Opnd_Range)) <
7021 Expr_Value (Low_Bound (Opnd_Range))
7025 elsif Is_Out_Of_Range
7026 (Low_Bound (Opnd_Range), Etype (Targ_Index),
7027 Assume_Valid => True)
7030 (High_Bound (Opnd_Range), Etype (Targ_Index),
7031 Assume_Valid => True)
7034 (Compile_Time_Constraint_Error
7035 (Wnode, "value out of range of}?", T_Typ));
7041 (Opnd_Range, Etype (Targ_Index)));
7045 Next_Index (Opnd_Index);
7046 Next_Index (Targ_Index);
7053 -- Construct the test and insert into the tree
7055 if Present (Cond) then
7057 Cond := Guard_Access (Cond, Loc, Ck_Node);
7061 (Make_Raise_Constraint_Error (Loc,
7063 Reason => CE_Range_Check_Failed));
7067 end Selected_Range_Checks;
7069 -------------------------------
7070 -- Storage_Checks_Suppressed --
7071 -------------------------------
7073 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
7075 if Present (E) and then Checks_May_Be_Suppressed (E) then
7076 return Is_Check_Suppressed (E, Storage_Check);
7078 return Scope_Suppress (Storage_Check);
7080 end Storage_Checks_Suppressed;
7082 ---------------------------
7083 -- Tag_Checks_Suppressed --
7084 ---------------------------
7086 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
7089 if Kill_Tag_Checks (E) then
7091 elsif Checks_May_Be_Suppressed (E) then
7092 return Is_Check_Suppressed (E, Tag_Check);
7096 return Scope_Suppress (Tag_Check);
7097 end Tag_Checks_Suppressed;
7099 --------------------------
7100 -- Validity_Check_Range --
7101 --------------------------
7103 procedure Validity_Check_Range (N : Node_Id) is
7105 if Validity_Checks_On and Validity_Check_Operands then
7106 if Nkind (N) = N_Range then
7107 Ensure_Valid (Low_Bound (N));
7108 Ensure_Valid (High_Bound (N));
7111 end Validity_Check_Range;
7113 --------------------------------
7114 -- Validity_Checks_Suppressed --
7115 --------------------------------
7117 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
7119 if Present (E) and then Checks_May_Be_Suppressed (E) then
7120 return Is_Check_Suppressed (E, Validity_Check);
7122 return Scope_Suppress (Validity_Check);
7124 end Validity_Checks_Suppressed;