1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2007, 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_Eval; use Sem_Eval;
47 with Sem_Ch3; use Sem_Ch3;
48 with Sem_Ch8; use Sem_Ch8;
49 with Sem_Res; use Sem_Res;
50 with Sem_Util; use Sem_Util;
51 with Sem_Warn; use Sem_Warn;
52 with Sinfo; use Sinfo;
53 with Sinput; use Sinput;
54 with Snames; use Snames;
55 with Sprint; use Sprint;
56 with Stand; use Stand;
57 with Targparm; use Targparm;
58 with Tbuild; use Tbuild;
59 with Ttypes; use Ttypes;
60 with Urealp; use Urealp;
61 with Validsw; use Validsw;
63 package body Checks is
65 -- General note: many of these routines are concerned with generating
66 -- checking code to make sure that constraint error is raised at runtime.
67 -- Clearly this code is only needed if the expander is active, since
68 -- otherwise we will not be generating code or going into the runtime
71 -- We therefore disconnect most of these checks if the expander is
72 -- inactive. This has the additional benefit that we do not need to
73 -- worry about the tree being messed up by previous errors (since errors
74 -- turn off expansion anyway).
76 -- There are a few exceptions to the above rule. For instance routines
77 -- such as Apply_Scalar_Range_Check that do not insert any code can be
78 -- safely called even when the Expander is inactive (but Errors_Detected
79 -- is 0). The benefit of executing this code when expansion is off, is
80 -- the ability to emit constraint error warning for static expressions
81 -- even when we are not generating code.
83 -------------------------------------
84 -- Suppression of Redundant Checks --
85 -------------------------------------
87 -- This unit implements a limited circuit for removal of redundant
88 -- checks. The processing is based on a tracing of simple sequential
89 -- flow. For any sequence of statements, we save expressions that are
90 -- marked to be checked, and then if the same expression appears later
91 -- with the same check, then under certain circumstances, the second
92 -- check can be suppressed.
94 -- Basically, we can suppress the check if we know for certain that
95 -- the previous expression has been elaborated (together with its
96 -- check), and we know that the exception frame is the same, and that
97 -- nothing has happened to change the result of the exception.
99 -- Let us examine each of these three conditions in turn to describe
100 -- how we ensure that this condition is met.
102 -- First, we need to know for certain that the previous expression has
103 -- been executed. This is done principly by the mechanism of calling
104 -- Conditional_Statements_Begin at the start of any statement sequence
105 -- and Conditional_Statements_End at the end. The End call causes all
106 -- checks remembered since the Begin call to be discarded. This does
107 -- miss a few cases, notably the case of a nested BEGIN-END block with
108 -- no exception handlers. But the important thing is to be conservative.
109 -- The other protection is that all checks are discarded if a label
110 -- is encountered, since then the assumption of sequential execution
111 -- is violated, and we don't know enough about the flow.
113 -- Second, we need to know that the exception frame is the same. We
114 -- do this by killing all remembered checks when we enter a new frame.
115 -- Again, that's over-conservative, but generally the cases we can help
116 -- with are pretty local anyway (like the body of a loop for example).
118 -- Third, we must be sure to forget any checks which are no longer valid.
119 -- This is done by two mechanisms, first the Kill_Checks_Variable call is
120 -- used to note any changes to local variables. We only attempt to deal
121 -- with checks involving local variables, so we do not need to worry
122 -- about global variables. Second, a call to any non-global procedure
123 -- causes us to abandon all stored checks, since such a all may affect
124 -- the values of any local variables.
126 -- The following define the data structures used to deal with remembering
127 -- checks so that redundant checks can be eliminated as described above.
129 -- Right now, the only expressions that we deal with are of the form of
130 -- simple local objects (either declared locally, or IN parameters) or
131 -- such objects plus/minus a compile time known constant. We can do
132 -- more later on if it seems worthwhile, but this catches many simple
133 -- cases in practice.
135 -- The following record type reflects a single saved check. An entry
136 -- is made in the stack of saved checks if and only if the expression
137 -- has been elaborated with the indicated checks.
139 type Saved_Check is record
141 -- Set True if entry is killed by Kill_Checks
144 -- The entity involved in the expression that is checked
147 -- A compile time value indicating the result of adding or
148 -- subtracting a compile time value. This value is to be
149 -- added to the value of the Entity. A value of zero is
150 -- used for the case of a simple entity reference.
152 Check_Type : Character;
153 -- This is set to 'R' for a range check (in which case Target_Type
154 -- is set to the target type for the range check) or to 'O' for an
155 -- overflow check (in which case Target_Type is set to Empty).
157 Target_Type : Entity_Id;
158 -- Used only if Do_Range_Check is set. Records the target type for
159 -- the check. We need this, because a check is a duplicate only if
160 -- it has a the same target type (or more accurately one with a
161 -- range that is smaller or equal to the stored target type of a
165 -- The following table keeps track of saved checks. Rather than use an
166 -- extensible table. We just use a table of fixed size, and we discard
167 -- any saved checks that do not fit. That's very unlikely to happen and
168 -- this is only an optimization in any case.
170 Saved_Checks : array (Int range 1 .. 200) of Saved_Check;
171 -- Array of saved checks
173 Num_Saved_Checks : Nat := 0;
174 -- Number of saved checks
176 -- The following stack keeps track of statement ranges. It is treated
177 -- as a stack. When Conditional_Statements_Begin is called, an entry
178 -- is pushed onto this stack containing the value of Num_Saved_Checks
179 -- at the time of the call. Then when Conditional_Statements_End is
180 -- called, this value is popped off and used to reset Num_Saved_Checks.
182 -- Note: again, this is a fixed length stack with a size that should
183 -- always be fine. If the value of the stack pointer goes above the
184 -- limit, then we just forget all saved checks.
186 Saved_Checks_Stack : array (Int range 1 .. 100) of Nat;
187 Saved_Checks_TOS : Nat := 0;
189 -----------------------
190 -- Local Subprograms --
191 -----------------------
193 procedure Apply_Float_Conversion_Check
195 Target_Typ : Entity_Id);
196 -- The checks on a conversion from a floating-point type to an integer
197 -- type are delicate. They have to be performed before conversion, they
198 -- have to raise an exception when the operand is a NaN, and rounding must
199 -- be taken into account to determine the safe bounds of the operand.
201 procedure Apply_Selected_Length_Checks
203 Target_Typ : Entity_Id;
204 Source_Typ : Entity_Id;
205 Do_Static : Boolean);
206 -- This is the subprogram that does all the work for Apply_Length_Check
207 -- and Apply_Static_Length_Check. Expr, Target_Typ and Source_Typ are as
208 -- described for the above routines. The Do_Static flag indicates that
209 -- only a static check is to be done.
211 procedure Apply_Selected_Range_Checks
213 Target_Typ : Entity_Id;
214 Source_Typ : Entity_Id;
215 Do_Static : Boolean);
216 -- This is the subprogram that does all the work for Apply_Range_Check.
217 -- Expr, Target_Typ and Source_Typ are as described for the above
218 -- routine. The Do_Static flag indicates that only a static check is
221 type Check_Type is new Check_Id range Access_Check .. Division_Check;
222 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean;
223 -- This function is used to see if an access or division by zero check is
224 -- needed. The check is to be applied to a single variable appearing in the
225 -- source, and N is the node for the reference. If N is not of this form,
226 -- True is returned with no further processing. If N is of the right form,
227 -- then further processing determines if the given Check is needed.
229 -- The particular circuit is to see if we have the case of a check that is
230 -- not needed because it appears in the right operand of a short circuited
231 -- conditional where the left operand guards the check. For example:
233 -- if Var = 0 or else Q / Var > 12 then
237 -- In this example, the division check is not required. At the same time
238 -- we can issue warnings for suspicious use of non-short-circuited forms,
241 -- if Var = 0 or Q / Var > 12 then
247 Check_Type : Character;
248 Target_Type : Entity_Id;
249 Entry_OK : out Boolean;
253 -- This routine is used by Enable_Range_Check and Enable_Overflow_Check
254 -- to see if a check is of the form for optimization, and if so, to see
255 -- if it has already been performed. Expr is the expression to check,
256 -- and Check_Type is 'R' for a range check, 'O' for an overflow check.
257 -- Target_Type is the target type for a range check, and Empty for an
258 -- overflow check. If the entry is not of the form for optimization,
259 -- then Entry_OK is set to False, and the remaining out parameters
260 -- are undefined. If the entry is OK, then Ent/Ofs are set to the
261 -- entity and offset from the expression. Check_Num is the number of
262 -- a matching saved entry in Saved_Checks, or zero if no such entry
265 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id;
266 -- If a discriminal is used in constraining a prival, Return reference
267 -- to the discriminal of the protected body (which renames the parameter
268 -- of the enclosing protected operation). This clumsy transformation is
269 -- needed because privals are created too late and their actual subtypes
270 -- are not available when analysing the bodies of the protected operations.
271 -- This function is called whenever the bound is an entity and the scope
272 -- indicates a protected operation. If the bound is an in-parameter of
273 -- a protected operation that is not a prival, the function returns the
275 -- To be cleaned up???
277 function Guard_Access
280 Ck_Node : Node_Id) return Node_Id;
281 -- In the access type case, guard the test with a test to ensure
282 -- that the access value is non-null, since the checks do not
283 -- not apply to null access values.
285 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr);
286 -- Called by Apply_{Length,Range}_Checks to rewrite the tree with the
287 -- Constraint_Error node.
289 function Range_Or_Validity_Checks_Suppressed
290 (Expr : Node_Id) return Boolean;
291 -- Returns True if either range or validity checks or both are suppressed
292 -- for the type of the given expression, or, if the expression is the name
293 -- of an entity, if these checks are suppressed for the entity.
295 function Selected_Length_Checks
297 Target_Typ : Entity_Id;
298 Source_Typ : Entity_Id;
299 Warn_Node : Node_Id) return Check_Result;
300 -- Like Apply_Selected_Length_Checks, except it doesn't modify
301 -- anything, just returns a list of nodes as described in the spec of
302 -- this package for the Range_Check function.
304 function Selected_Range_Checks
306 Target_Typ : Entity_Id;
307 Source_Typ : Entity_Id;
308 Warn_Node : Node_Id) return Check_Result;
309 -- Like Apply_Selected_Range_Checks, except it doesn't modify anything,
310 -- just returns a list of nodes as described in the spec of this package
311 -- for the Range_Check function.
313 ------------------------------
314 -- Access_Checks_Suppressed --
315 ------------------------------
317 function Access_Checks_Suppressed (E : Entity_Id) return Boolean is
319 if Present (E) and then Checks_May_Be_Suppressed (E) then
320 return Is_Check_Suppressed (E, Access_Check);
322 return Scope_Suppress (Access_Check);
324 end Access_Checks_Suppressed;
326 -------------------------------------
327 -- Accessibility_Checks_Suppressed --
328 -------------------------------------
330 function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean is
332 if Present (E) and then Checks_May_Be_Suppressed (E) then
333 return Is_Check_Suppressed (E, Accessibility_Check);
335 return Scope_Suppress (Accessibility_Check);
337 end Accessibility_Checks_Suppressed;
339 -----------------------------
340 -- Activate_Division_Check --
341 -----------------------------
343 procedure Activate_Division_Check (N : Node_Id) is
345 Set_Do_Division_Check (N, True);
346 Possible_Local_Raise (N, Standard_Constraint_Error);
347 end Activate_Division_Check;
349 -----------------------------
350 -- Activate_Overflow_Check --
351 -----------------------------
353 procedure Activate_Overflow_Check (N : Node_Id) is
355 Set_Do_Overflow_Check (N, True);
356 Possible_Local_Raise (N, Standard_Constraint_Error);
357 end Activate_Overflow_Check;
359 --------------------------
360 -- Activate_Range_Check --
361 --------------------------
363 procedure Activate_Range_Check (N : Node_Id) is
365 Set_Do_Range_Check (N, True);
366 Possible_Local_Raise (N, Standard_Constraint_Error);
367 end Activate_Range_Check;
369 ---------------------------------
370 -- Alignment_Checks_Suppressed --
371 ---------------------------------
373 function Alignment_Checks_Suppressed (E : Entity_Id) return Boolean is
375 if Present (E) and then Checks_May_Be_Suppressed (E) then
376 return Is_Check_Suppressed (E, Alignment_Check);
378 return Scope_Suppress (Alignment_Check);
380 end Alignment_Checks_Suppressed;
382 -------------------------
383 -- Append_Range_Checks --
384 -------------------------
386 procedure Append_Range_Checks
387 (Checks : Check_Result;
389 Suppress_Typ : Entity_Id;
390 Static_Sloc : Source_Ptr;
393 Internal_Flag_Node : constant Node_Id := Flag_Node;
394 Internal_Static_Sloc : constant Source_Ptr := Static_Sloc;
396 Checks_On : constant Boolean :=
397 (not Index_Checks_Suppressed (Suppress_Typ))
399 (not Range_Checks_Suppressed (Suppress_Typ));
402 -- For now we just return if Checks_On is false, however this should
403 -- be enhanced to check for an always True value in the condition
404 -- and to generate a compilation warning???
406 if not Checks_On then
411 exit when No (Checks (J));
413 if Nkind (Checks (J)) = N_Raise_Constraint_Error
414 and then Present (Condition (Checks (J)))
416 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
417 Append_To (Stmts, Checks (J));
418 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
424 Make_Raise_Constraint_Error (Internal_Static_Sloc,
425 Reason => CE_Range_Check_Failed));
428 end Append_Range_Checks;
430 ------------------------
431 -- Apply_Access_Check --
432 ------------------------
434 procedure Apply_Access_Check (N : Node_Id) is
435 P : constant Node_Id := Prefix (N);
438 -- We do not need checks if we are not generating code (i.e. the
439 -- expander is not active). This is not just an optimization, there
440 -- are cases (e.g. with pragma Debug) where generating the checks
441 -- can cause real trouble).
443 if not Expander_Active then
447 -- No check if short circuiting makes check unnecessary
449 if not Check_Needed (P, Access_Check) then
453 -- Otherwise go ahead and install the check
455 Install_Null_Excluding_Check (P);
456 end Apply_Access_Check;
458 -------------------------------
459 -- Apply_Accessibility_Check --
460 -------------------------------
462 procedure Apply_Accessibility_Check (N : Node_Id; Typ : Entity_Id) is
463 Loc : constant Source_Ptr := Sloc (N);
464 Param_Ent : constant Entity_Id := Param_Entity (N);
465 Param_Level : Node_Id;
466 Type_Level : Node_Id;
469 if Inside_A_Generic then
472 -- Only apply the run-time check if the access parameter
473 -- has an associated extra access level parameter and
474 -- when the level of the type is less deep than the level
475 -- of the access parameter.
477 elsif Present (Param_Ent)
478 and then Present (Extra_Accessibility (Param_Ent))
479 and then UI_Gt (Object_Access_Level (N),
480 Type_Access_Level (Typ))
481 and then not Accessibility_Checks_Suppressed (Param_Ent)
482 and then not Accessibility_Checks_Suppressed (Typ)
485 New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc);
488 Make_Integer_Literal (Loc, Type_Access_Level (Typ));
490 -- Raise Program_Error if the accessibility level of the the access
491 -- parameter is deeper than the level of the target access type.
494 Make_Raise_Program_Error (Loc,
497 Left_Opnd => Param_Level,
498 Right_Opnd => Type_Level),
499 Reason => PE_Accessibility_Check_Failed));
501 Analyze_And_Resolve (N);
503 end Apply_Accessibility_Check;
505 --------------------------------
506 -- Apply_Address_Clause_Check --
507 --------------------------------
509 procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is
510 AC : constant Node_Id := Address_Clause (E);
511 Loc : constant Source_Ptr := Sloc (AC);
512 Typ : constant Entity_Id := Etype (E);
513 Aexp : constant Node_Id := Expression (AC);
516 -- Address expression (not necessarily the same as Aexp, for example
517 -- when Aexp is a reference to a constant, in which case Expr gets
518 -- reset to reference the value expression of the constant.
520 Size_Warning_Output : Boolean := False;
521 -- If we output a size warning we set this True, to stop generating
522 -- what is likely to be an unuseful redundant alignment warning.
524 procedure Compile_Time_Bad_Alignment;
525 -- Post error warnings when alignment is known to be incompatible. Note
526 -- that we do not go as far as inserting a raise of Program_Error since
527 -- this is an erroneous case, and it may happen that we are lucky and an
528 -- underaligned address turns out to be OK after all. Also this warning
529 -- is suppressed if we already complained about the size.
531 --------------------------------
532 -- Compile_Time_Bad_Alignment --
533 --------------------------------
535 procedure Compile_Time_Bad_Alignment is
537 if not Size_Warning_Output
538 and then Address_Clause_Overlay_Warnings
541 ("?specified address for& may be inconsistent with alignment ",
544 ("\?program execution may be erroneous (RM 13.3(27))",
547 end Compile_Time_Bad_Alignment;
549 -- Start of processing for Apply_Address_Clause_Check
552 -- First obtain expression from address clause
554 Expr := Expression (AC);
556 -- The following loop digs for the real expression to use in the check
559 -- For constant, get constant expression
561 if Is_Entity_Name (Expr)
562 and then Ekind (Entity (Expr)) = E_Constant
564 Expr := Constant_Value (Entity (Expr));
566 -- For unchecked conversion, get result to convert
568 elsif Nkind (Expr) = N_Unchecked_Type_Conversion then
569 Expr := Expression (Expr);
571 -- For (common case) of To_Address call, get argument
573 elsif Nkind (Expr) = N_Function_Call
574 and then Is_Entity_Name (Name (Expr))
575 and then Is_RTE (Entity (Name (Expr)), RE_To_Address)
577 Expr := First (Parameter_Associations (Expr));
579 if Nkind (Expr) = N_Parameter_Association then
580 Expr := Explicit_Actual_Parameter (Expr);
583 -- We finally have the real expression
590 -- Output a warning if we have the situation of
592 -- for X'Address use Y'Address
594 -- and X and Y both have known object sizes, and Y is smaller than X
596 if Nkind (Expr) = N_Attribute_Reference
597 and then Attribute_Name (Expr) = Name_Address
598 and then Is_Entity_Name (Prefix (Expr))
601 Exp_Ent : constant Entity_Id := Entity (Prefix (Expr));
602 Obj_Size : Uint := No_Uint;
603 Exp_Size : Uint := No_Uint;
606 if Known_Esize (E) then
607 Obj_Size := Esize (E);
608 elsif Known_Esize (Etype (E)) then
609 Obj_Size := Esize (Etype (E));
612 if Known_Esize (Exp_Ent) then
613 Exp_Size := Esize (Exp_Ent);
614 elsif Known_Esize (Etype (Exp_Ent)) then
615 Exp_Size := Esize (Etype (Exp_Ent));
618 if Obj_Size /= No_Uint
619 and then Exp_Size /= No_Uint
620 and then Obj_Size > Exp_Size
621 and then not Warnings_Off (E)
623 if Address_Clause_Overlay_Warnings then
625 ("?& overlays smaller object", Aexp, E);
627 ("\?program execution may be erroneous", Aexp, E);
628 Size_Warning_Output := True;
634 -- See if alignment check needed. Note that we never need a check if the
635 -- maximum alignment is one, since the check will always succeed.
637 -- Note: we do not check for checks suppressed here, since that check
638 -- was done in Sem_Ch13 when the address clause was processed. We are
639 -- only called if checks were not suppressed. The reason for this is
640 -- that we have to delay the call to Apply_Alignment_Check till freeze
641 -- time (so that all types etc are elaborated), but we have to check
642 -- the status of check suppressing at the point of the address clause.
645 or else not Check_Address_Alignment (AC)
646 or else Maximum_Alignment = 1
651 -- See if we know that Expr is a bad alignment at compile time
653 if Compile_Time_Known_Value (Expr)
654 and then (Known_Alignment (E) or else Known_Alignment (Typ))
657 AL : Uint := Alignment (Typ);
660 -- The object alignment might be more restrictive than the
663 if Known_Alignment (E) then
667 if Expr_Value (Expr) mod AL /= 0 then
668 Compile_Time_Bad_Alignment;
674 -- If the expression has the form X'Address, then we can find out if
675 -- the object X has an alignment that is compatible with the object E.
677 elsif Nkind (Expr) = N_Attribute_Reference
678 and then Attribute_Name (Expr) = Name_Address
681 AR : constant Alignment_Result :=
682 Has_Compatible_Alignment (E, Prefix (Expr));
684 if AR = Known_Compatible then
686 elsif AR = Known_Incompatible then
687 Compile_Time_Bad_Alignment;
692 -- Here we do not know if the value is acceptable. Stricly we don't have
693 -- to do anything, since if the alignment is bad, we have an erroneous
694 -- program. However we are allowed to check for erroneous conditions and
695 -- we decide to do this by default if the check is not suppressed.
697 -- However, don't do the check if elaboration code is unwanted
699 if Restriction_Active (No_Elaboration_Code) then
702 -- Generate a check to raise PE if alignment may be inappropriate
705 -- If the original expression is a non-static constant, use the
706 -- name of the constant itself rather than duplicating its
707 -- defining expression, which was extracted above.
709 -- Note: Expr is empty if the address-clause is applied to in-mode
710 -- actuals (allowed by 13.1(22)).
712 if not Present (Expr)
714 (Is_Entity_Name (Expression (AC))
715 and then Ekind (Entity (Expression (AC))) = E_Constant
716 and then Nkind (Parent (Entity (Expression (AC))))
717 = N_Object_Declaration)
719 Expr := New_Copy_Tree (Expression (AC));
721 Remove_Side_Effects (Expr);
724 Insert_After_And_Analyze (N,
725 Make_Raise_Program_Error (Loc,
732 (RTE (RE_Integer_Address), Expr),
734 Make_Attribute_Reference (Loc,
735 Prefix => New_Occurrence_Of (E, Loc),
736 Attribute_Name => Name_Alignment)),
737 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
738 Reason => PE_Misaligned_Address_Value),
739 Suppress => All_Checks);
744 -- If we have some missing run time component in configurable run time
745 -- mode then just skip the check (it is not required in any case).
747 when RE_Not_Available =>
749 end Apply_Address_Clause_Check;
751 -------------------------------------
752 -- Apply_Arithmetic_Overflow_Check --
753 -------------------------------------
755 -- This routine is called only if the type is an integer type, and
756 -- a software arithmetic overflow check must be performed for op
757 -- (add, subtract, multiply). The check is performed only if
758 -- Software_Overflow_Checking is enabled and Do_Overflow_Check
759 -- is set. In this case we expand the operation into a more complex
760 -- sequence of tests that ensures that overflow is properly caught.
762 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
763 Loc : constant Source_Ptr := Sloc (N);
764 Typ : constant Entity_Id := Etype (N);
765 Rtyp : constant Entity_Id := Root_Type (Typ);
766 Siz : constant Int := UI_To_Int (Esize (Rtyp));
767 Dsiz : constant Int := Siz * 2;
774 -- Skip this if overflow checks are done in back end, or the overflow
775 -- flag is not set anyway, or we are not doing code expansion.
776 -- Special case CLI target, where arithmetic overflow checks can be
777 -- performed for integer and long_integer
779 if Backend_Overflow_Checks_On_Target
780 or else (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
781 or else not Do_Overflow_Check (N)
782 or else not Expander_Active
787 -- Otherwise, we generate the full general code for front end overflow
788 -- detection, which works by doing arithmetic in a larger type:
794 -- Typ (Checktyp (x) op Checktyp (y));
796 -- where Typ is the type of the original expression, and Checktyp is
797 -- an integer type of sufficient length to hold the largest possible
800 -- In the case where check type exceeds the size of Long_Long_Integer,
801 -- we use a different approach, expanding to:
803 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
805 -- where xxx is Add, Multiply or Subtract as appropriate
807 -- Find check type if one exists
809 if Dsiz <= Standard_Integer_Size then
810 Ctyp := Standard_Integer;
812 elsif Dsiz <= Standard_Long_Long_Integer_Size then
813 Ctyp := Standard_Long_Long_Integer;
815 -- No check type exists, use runtime call
818 if Nkind (N) = N_Op_Add then
819 Cent := RE_Add_With_Ovflo_Check;
821 elsif Nkind (N) = N_Op_Multiply then
822 Cent := RE_Multiply_With_Ovflo_Check;
825 pragma Assert (Nkind (N) = N_Op_Subtract);
826 Cent := RE_Subtract_With_Ovflo_Check;
831 Make_Function_Call (Loc,
832 Name => New_Reference_To (RTE (Cent), Loc),
833 Parameter_Associations => New_List (
834 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
835 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
837 Analyze_And_Resolve (N, Typ);
841 -- If we fall through, we have the case where we do the arithmetic in
842 -- the next higher type and get the check by conversion. In these cases
843 -- Ctyp is set to the type to be used as the check type.
845 Opnod := Relocate_Node (N);
847 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
850 Set_Etype (Opnd, Ctyp);
851 Set_Analyzed (Opnd, True);
852 Set_Left_Opnd (Opnod, Opnd);
854 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
857 Set_Etype (Opnd, Ctyp);
858 Set_Analyzed (Opnd, True);
859 Set_Right_Opnd (Opnod, Opnd);
861 -- The type of the operation changes to the base type of the check type,
862 -- and we reset the overflow check indication, since clearly no overflow
863 -- is possible now that we are using a double length type. We also set
864 -- the Analyzed flag to avoid a recursive attempt to expand the node.
866 Set_Etype (Opnod, Base_Type (Ctyp));
867 Set_Do_Overflow_Check (Opnod, False);
868 Set_Analyzed (Opnod, True);
870 -- Now build the outer conversion
872 Opnd := OK_Convert_To (Typ, Opnod);
874 Set_Etype (Opnd, Typ);
876 -- In the discrete type case, we directly generate the range check for
877 -- the outer operand. This range check will implement the required
880 if Is_Discrete_Type (Typ) then
882 Generate_Range_Check (Expression (N), Typ, CE_Overflow_Check_Failed);
884 -- For other types, we enable overflow checking on the conversion,
885 -- after setting the node as analyzed to prevent recursive attempts
886 -- to expand the conversion node.
889 Set_Analyzed (Opnd, True);
890 Enable_Overflow_Check (Opnd);
895 when RE_Not_Available =>
897 end Apply_Arithmetic_Overflow_Check;
899 ----------------------------
900 -- Apply_Constraint_Check --
901 ----------------------------
903 procedure Apply_Constraint_Check
906 No_Sliding : Boolean := False)
908 Desig_Typ : Entity_Id;
911 if Inside_A_Generic then
914 elsif Is_Scalar_Type (Typ) then
915 Apply_Scalar_Range_Check (N, Typ);
917 elsif Is_Array_Type (Typ) then
919 -- A useful optimization: an aggregate with only an others clause
920 -- always has the right bounds.
922 if Nkind (N) = N_Aggregate
923 and then No (Expressions (N))
925 (First (Choices (First (Component_Associations (N)))))
931 if Is_Constrained (Typ) then
932 Apply_Length_Check (N, Typ);
935 Apply_Range_Check (N, Typ);
938 Apply_Range_Check (N, Typ);
941 elsif (Is_Record_Type (Typ)
942 or else Is_Private_Type (Typ))
943 and then Has_Discriminants (Base_Type (Typ))
944 and then Is_Constrained (Typ)
946 Apply_Discriminant_Check (N, Typ);
948 elsif Is_Access_Type (Typ) then
950 Desig_Typ := Designated_Type (Typ);
952 -- No checks necessary if expression statically null
954 if Known_Null (N) then
955 if Can_Never_Be_Null (Typ) then
956 Install_Null_Excluding_Check (N);
959 -- No sliding possible on access to arrays
961 elsif Is_Array_Type (Desig_Typ) then
962 if Is_Constrained (Desig_Typ) then
963 Apply_Length_Check (N, Typ);
966 Apply_Range_Check (N, Typ);
968 elsif Has_Discriminants (Base_Type (Desig_Typ))
969 and then Is_Constrained (Desig_Typ)
971 Apply_Discriminant_Check (N, Typ);
974 -- Apply the the 2005 Null_Excluding check. Note that we do not apply
975 -- this check if the constraint node is illegal, as shown by having
976 -- an error posted. This additional guard prevents cascaded errors
977 -- and compiler aborts on illegal programs involving Ada 2005 checks.
979 if Can_Never_Be_Null (Typ)
980 and then not Can_Never_Be_Null (Etype (N))
981 and then not Error_Posted (N)
983 Install_Null_Excluding_Check (N);
986 end Apply_Constraint_Check;
988 ------------------------------
989 -- Apply_Discriminant_Check --
990 ------------------------------
992 procedure Apply_Discriminant_Check
995 Lhs : Node_Id := Empty)
997 Loc : constant Source_Ptr := Sloc (N);
998 Do_Access : constant Boolean := Is_Access_Type (Typ);
999 S_Typ : Entity_Id := Etype (N);
1003 function Is_Aliased_Unconstrained_Component return Boolean;
1004 -- It is possible for an aliased component to have a nominal
1005 -- unconstrained subtype (through instantiation). If this is a
1006 -- discriminated component assigned in the expansion of an aggregate
1007 -- in an initialization, the check must be suppressed. This unusual
1008 -- situation requires a predicate of its own.
1010 ----------------------------------------
1011 -- Is_Aliased_Unconstrained_Component --
1012 ----------------------------------------
1014 function Is_Aliased_Unconstrained_Component return Boolean is
1019 if Nkind (Lhs) /= N_Selected_Component then
1022 Comp := Entity (Selector_Name (Lhs));
1023 Pref := Prefix (Lhs);
1026 if Ekind (Comp) /= E_Component
1027 or else not Is_Aliased (Comp)
1032 return not Comes_From_Source (Pref)
1033 and then In_Instance
1034 and then not Is_Constrained (Etype (Comp));
1035 end Is_Aliased_Unconstrained_Component;
1037 -- Start of processing for Apply_Discriminant_Check
1041 T_Typ := Designated_Type (Typ);
1046 -- Nothing to do if discriminant checks are suppressed or else no code
1047 -- is to be generated
1049 if not Expander_Active
1050 or else Discriminant_Checks_Suppressed (T_Typ)
1055 -- No discriminant checks necessary for an access when expression is
1056 -- statically Null. This is not only an optimization, it is fundamental
1057 -- because otherwise discriminant checks may be generated in init procs
1058 -- for types containing an access to a not-yet-frozen record, causing a
1059 -- deadly forward reference.
1061 -- Also, if the expression is of an access type whose designated type is
1062 -- incomplete, then the access value must be null and we suppress the
1065 if Known_Null (N) then
1068 elsif Is_Access_Type (S_Typ) then
1069 S_Typ := Designated_Type (S_Typ);
1071 if Ekind (S_Typ) = E_Incomplete_Type then
1076 -- If an assignment target is present, then we need to generate the
1077 -- actual subtype if the target is a parameter or aliased object with
1078 -- an unconstrained nominal subtype.
1080 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1081 -- subtype to the parameter and dereference cases, since other aliased
1082 -- objects are unconstrained (unless the nominal subtype is explicitly
1083 -- constrained). (But we also need to test for renamings???)
1086 and then (Present (Param_Entity (Lhs))
1087 or else (Ada_Version < Ada_05
1088 and then not Is_Constrained (T_Typ)
1089 and then Is_Aliased_View (Lhs)
1090 and then not Is_Aliased_Unconstrained_Component)
1091 or else (Ada_Version >= Ada_05
1092 and then not Is_Constrained (T_Typ)
1093 and then Nkind (Lhs) = N_Explicit_Dereference
1094 and then Nkind (Original_Node (Lhs)) /=
1097 T_Typ := Get_Actual_Subtype (Lhs);
1100 -- Nothing to do if the type is unconstrained (this is the case where
1101 -- the actual subtype in the RM sense of N is unconstrained and no check
1104 if not Is_Constrained (T_Typ) then
1107 -- Ada 2005: nothing to do if the type is one for which there is a
1108 -- partial view that is constrained.
1110 elsif Ada_Version >= Ada_05
1111 and then Has_Constrained_Partial_View (Base_Type (T_Typ))
1116 -- Nothing to do if the type is an Unchecked_Union
1118 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1122 -- Suppress checks if the subtypes are the same. the check must be
1123 -- preserved in an assignment to a formal, because the constraint is
1124 -- given by the actual.
1126 if Nkind (Original_Node (N)) /= N_Allocator
1128 or else not Is_Entity_Name (Lhs)
1129 or else No (Param_Entity (Lhs)))
1132 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1133 and then not Is_Aliased_View (Lhs)
1138 -- We can also eliminate checks on allocators with a subtype mark that
1139 -- coincides with the context type. The context type may be a subtype
1140 -- without a constraint (common case, a generic actual).
1142 elsif Nkind (Original_Node (N)) = N_Allocator
1143 and then Is_Entity_Name (Expression (Original_Node (N)))
1146 Alloc_Typ : constant Entity_Id :=
1147 Entity (Expression (Original_Node (N)));
1150 if Alloc_Typ = T_Typ
1151 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1152 and then Is_Entity_Name (
1153 Subtype_Indication (Parent (T_Typ)))
1154 and then Alloc_Typ = Base_Type (T_Typ))
1162 -- See if we have a case where the types are both constrained, and all
1163 -- the constraints are constants. In this case, we can do the check
1164 -- successfully at compile time.
1166 -- We skip this check for the case where the node is a rewritten`
1167 -- allocator, because it already carries the context subtype, and
1168 -- extracting the discriminants from the aggregate is messy.
1170 if Is_Constrained (S_Typ)
1171 and then Nkind (Original_Node (N)) /= N_Allocator
1181 -- S_Typ may not have discriminants in the case where it is a
1182 -- private type completed by a default discriminated type. In that
1183 -- case, we need to get the constraints from the underlying_type.
1184 -- If the underlying type is unconstrained (i.e. has no default
1185 -- discriminants) no check is needed.
1187 if Has_Discriminants (S_Typ) then
1188 Discr := First_Discriminant (S_Typ);
1189 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1192 Discr := First_Discriminant (Underlying_Type (S_Typ));
1195 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1201 -- A further optimization: if T_Typ is derived from S_Typ
1202 -- without imposing a constraint, no check is needed.
1204 if Nkind (Original_Node (Parent (T_Typ))) =
1205 N_Full_Type_Declaration
1208 Type_Def : constant Node_Id :=
1210 (Original_Node (Parent (T_Typ)));
1212 if Nkind (Type_Def) = N_Derived_Type_Definition
1213 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1214 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1222 DconT := First_Elmt (Discriminant_Constraint (T_Typ));
1224 while Present (Discr) loop
1225 ItemS := Node (DconS);
1226 ItemT := Node (DconT);
1228 -- For a discriminated component type constrained by the
1229 -- current instance of an enclosing type, there is no
1230 -- applicable discriminant check.
1232 if Nkind (ItemT) = N_Attribute_Reference
1233 and then Is_Access_Type (Etype (ItemT))
1234 and then Is_Entity_Name (Prefix (ItemT))
1235 and then Is_Type (Entity (Prefix (ItemT)))
1241 not Is_OK_Static_Expression (ItemS)
1243 not Is_OK_Static_Expression (ItemT);
1245 if Expr_Value (ItemS) /= Expr_Value (ItemT) then
1246 if Do_Access then -- needs run-time check.
1249 Apply_Compile_Time_Constraint_Error
1250 (N, "incorrect value for discriminant&?",
1251 CE_Discriminant_Check_Failed, Ent => Discr);
1258 Next_Discriminant (Discr);
1267 -- Here we need a discriminant check. First build the expression
1268 -- for the comparisons of the discriminants:
1270 -- (n.disc1 /= typ.disc1) or else
1271 -- (n.disc2 /= typ.disc2) or else
1273 -- (n.discn /= typ.discn)
1275 Cond := Build_Discriminant_Checks (N, T_Typ);
1277 -- If Lhs is set and is a parameter, then the condition is
1278 -- guarded by: lhs'constrained and then (condition built above)
1280 if Present (Param_Entity (Lhs)) then
1284 Make_Attribute_Reference (Loc,
1285 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1286 Attribute_Name => Name_Constrained),
1287 Right_Opnd => Cond);
1291 Cond := Guard_Access (Cond, Loc, N);
1295 Make_Raise_Constraint_Error (Loc,
1297 Reason => CE_Discriminant_Check_Failed));
1298 end Apply_Discriminant_Check;
1300 ------------------------
1301 -- Apply_Divide_Check --
1302 ------------------------
1304 procedure Apply_Divide_Check (N : Node_Id) is
1305 Loc : constant Source_Ptr := Sloc (N);
1306 Typ : constant Entity_Id := Etype (N);
1307 Left : constant Node_Id := Left_Opnd (N);
1308 Right : constant Node_Id := Right_Opnd (N);
1320 and then not Backend_Divide_Checks_On_Target
1321 and then Check_Needed (Right, Division_Check)
1323 Determine_Range (Right, ROK, Rlo, Rhi);
1325 -- See if division by zero possible, and if so generate test. This
1326 -- part of the test is not controlled by the -gnato switch.
1328 if Do_Division_Check (N) then
1329 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1331 Make_Raise_Constraint_Error (Loc,
1334 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1335 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1336 Reason => CE_Divide_By_Zero));
1340 -- Test for extremely annoying case of xxx'First divided by -1
1342 if Do_Overflow_Check (N) then
1343 if Nkind (N) = N_Op_Divide
1344 and then Is_Signed_Integer_Type (Typ)
1346 Determine_Range (Left, LOK, Llo, Lhi);
1347 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1349 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1351 ((not LOK) or else (Llo = LLB))
1354 Make_Raise_Constraint_Error (Loc,
1360 Duplicate_Subexpr_Move_Checks (Left),
1361 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1365 Duplicate_Subexpr (Right),
1367 Make_Integer_Literal (Loc, -1))),
1368 Reason => CE_Overflow_Check_Failed));
1373 end Apply_Divide_Check;
1375 ----------------------------------
1376 -- Apply_Float_Conversion_Check --
1377 ----------------------------------
1379 -- Let F and I be the source and target types of the conversion. The RM
1380 -- specifies that a floating-point value X is rounded to the nearest
1381 -- integer, with halfway cases being rounded away from zero. The rounded
1382 -- value of X is checked against I'Range.
1384 -- The catch in the above paragraph is that there is no good way to know
1385 -- whether the round-to-integer operation resulted in overflow. A remedy is
1386 -- to perform a range check in the floating-point domain instead, however:
1388 -- (1) The bounds may not be known at compile time
1389 -- (2) The check must take into account rounding or truncation.
1390 -- (3) The range of type I may not be exactly representable in F.
1391 -- (4) For the rounding case, The end-points I'First - 0.5 and
1392 -- I'Last + 0.5 may or may not be in range, depending on the
1393 -- sign of I'First and I'Last.
1394 -- (5) X may be a NaN, which will fail any comparison
1396 -- The following steps correctly convert X with rounding:
1398 -- (1) If either I'First or I'Last is not known at compile time, use
1399 -- I'Base instead of I in the next three steps and perform a
1400 -- regular range check against I'Range after conversion.
1401 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1402 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1403 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1404 -- In other words, take one of the closest floating-point numbers
1405 -- (which is an integer value) to I'First, and see if it is in
1407 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1408 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1409 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1410 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1411 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1413 -- For the truncating case, replace steps (2) and (3) as follows:
1414 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1415 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1417 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1418 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1421 procedure Apply_Float_Conversion_Check
1423 Target_Typ : Entity_Id)
1425 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1426 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1427 Loc : constant Source_Ptr := Sloc (Ck_Node);
1428 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1429 Target_Base : constant Entity_Id :=
1430 Implementation_Base_Type (Target_Typ);
1432 Par : constant Node_Id := Parent (Ck_Node);
1433 pragma Assert (Nkind (Par) = N_Type_Conversion);
1434 -- Parent of check node, must be a type conversion
1436 Truncate : constant Boolean := Float_Truncate (Par);
1437 Max_Bound : constant Uint :=
1439 (Machine_Radix (Expr_Type),
1440 Machine_Mantissa (Expr_Type) - 1) - 1;
1442 -- Largest bound, so bound plus or minus half is a machine number of F
1444 Ifirst, Ilast : Uint;
1445 -- Bounds of integer type
1448 -- Bounds to check in floating-point domain
1450 Lo_OK, Hi_OK : Boolean;
1451 -- True iff Lo resp. Hi belongs to I'Range
1453 Lo_Chk, Hi_Chk : Node_Id;
1454 -- Expressions that are False iff check fails
1456 Reason : RT_Exception_Code;
1459 if not Compile_Time_Known_Value (LB)
1460 or not Compile_Time_Known_Value (HB)
1463 -- First check that the value falls in the range of the base type,
1464 -- to prevent overflow during conversion and then perform a
1465 -- regular range check against the (dynamic) bounds.
1467 pragma Assert (Target_Base /= Target_Typ);
1469 Temp : constant Entity_Id :=
1470 Make_Defining_Identifier (Loc,
1471 Chars => New_Internal_Name ('T'));
1474 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1475 Set_Etype (Temp, Target_Base);
1477 Insert_Action (Parent (Par),
1478 Make_Object_Declaration (Loc,
1479 Defining_Identifier => Temp,
1480 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1481 Expression => New_Copy_Tree (Par)),
1482 Suppress => All_Checks);
1485 Make_Raise_Constraint_Error (Loc,
1488 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1489 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1490 Reason => CE_Range_Check_Failed));
1491 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
1497 -- Get the bounds of the target type
1499 Ifirst := Expr_Value (LB);
1500 Ilast := Expr_Value (HB);
1502 -- Check against lower bound
1504 if Truncate and then Ifirst > 0 then
1505 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
1509 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
1512 elsif abs (Ifirst) < Max_Bound then
1513 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
1514 Lo_OK := (Ifirst > 0);
1517 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
1518 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
1523 -- Lo_Chk := (X >= Lo)
1525 Lo_Chk := Make_Op_Ge (Loc,
1526 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1527 Right_Opnd => Make_Real_Literal (Loc, Lo));
1530 -- Lo_Chk := (X > Lo)
1532 Lo_Chk := Make_Op_Gt (Loc,
1533 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1534 Right_Opnd => Make_Real_Literal (Loc, Lo));
1537 -- Check against higher bound
1539 if Truncate and then Ilast < 0 then
1540 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
1544 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
1547 elsif abs (Ilast) < Max_Bound then
1548 Hi := UR_From_Uint (Ilast) + Ureal_Half;
1549 Hi_OK := (Ilast < 0);
1551 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
1552 Hi_OK := (Hi <= UR_From_Uint (Ilast));
1557 -- Hi_Chk := (X <= Hi)
1559 Hi_Chk := Make_Op_Le (Loc,
1560 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1561 Right_Opnd => Make_Real_Literal (Loc, Hi));
1564 -- Hi_Chk := (X < Hi)
1566 Hi_Chk := Make_Op_Lt (Loc,
1567 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1568 Right_Opnd => Make_Real_Literal (Loc, Hi));
1571 -- If the bounds of the target type are the same as those of the base
1572 -- type, the check is an overflow check as a range check is not
1573 -- performed in these cases.
1575 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
1576 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
1578 Reason := CE_Overflow_Check_Failed;
1580 Reason := CE_Range_Check_Failed;
1583 -- Raise CE if either conditions does not hold
1585 Insert_Action (Ck_Node,
1586 Make_Raise_Constraint_Error (Loc,
1587 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
1589 end Apply_Float_Conversion_Check;
1591 ------------------------
1592 -- Apply_Length_Check --
1593 ------------------------
1595 procedure Apply_Length_Check
1597 Target_Typ : Entity_Id;
1598 Source_Typ : Entity_Id := Empty)
1601 Apply_Selected_Length_Checks
1602 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1603 end Apply_Length_Check;
1605 -----------------------
1606 -- Apply_Range_Check --
1607 -----------------------
1609 procedure Apply_Range_Check
1611 Target_Typ : Entity_Id;
1612 Source_Typ : Entity_Id := Empty)
1615 Apply_Selected_Range_Checks
1616 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1617 end Apply_Range_Check;
1619 ------------------------------
1620 -- Apply_Scalar_Range_Check --
1621 ------------------------------
1623 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
1624 -- off if it is already set on.
1626 procedure Apply_Scalar_Range_Check
1628 Target_Typ : Entity_Id;
1629 Source_Typ : Entity_Id := Empty;
1630 Fixed_Int : Boolean := False)
1632 Parnt : constant Node_Id := Parent (Expr);
1634 Arr : Node_Id := Empty; -- initialize to prevent warning
1635 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
1638 Is_Subscr_Ref : Boolean;
1639 -- Set true if Expr is a subscript
1641 Is_Unconstrained_Subscr_Ref : Boolean;
1642 -- Set true if Expr is a subscript of an unconstrained array. In this
1643 -- case we do not attempt to do an analysis of the value against the
1644 -- range of the subscript, since we don't know the actual subtype.
1647 -- Set to True if Expr should be regarded as a real value even though
1648 -- the type of Expr might be discrete.
1650 procedure Bad_Value;
1651 -- Procedure called if value is determined to be out of range
1657 procedure Bad_Value is
1659 Apply_Compile_Time_Constraint_Error
1660 (Expr, "value not in range of}?", CE_Range_Check_Failed,
1665 -- Start of processing for Apply_Scalar_Range_Check
1668 -- Return if check obviously not needed
1671 -- Not needed inside generic
1675 -- Not needed if previous error
1677 or else Target_Typ = Any_Type
1678 or else Nkind (Expr) = N_Error
1680 -- Not needed for non-scalar type
1682 or else not Is_Scalar_Type (Target_Typ)
1684 -- Not needed if we know node raises CE already
1686 or else Raises_Constraint_Error (Expr)
1691 -- Now, see if checks are suppressed
1694 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
1696 if Is_Subscr_Ref then
1697 Arr := Prefix (Parnt);
1698 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
1701 if not Do_Range_Check (Expr) then
1703 -- Subscript reference. Check for Index_Checks suppressed
1705 if Is_Subscr_Ref then
1707 -- Check array type and its base type
1709 if Index_Checks_Suppressed (Arr_Typ)
1710 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
1714 -- Check array itself if it is an entity name
1716 elsif Is_Entity_Name (Arr)
1717 and then Index_Checks_Suppressed (Entity (Arr))
1721 -- Check expression itself if it is an entity name
1723 elsif Is_Entity_Name (Expr)
1724 and then Index_Checks_Suppressed (Entity (Expr))
1729 -- All other cases, check for Range_Checks suppressed
1732 -- Check target type and its base type
1734 if Range_Checks_Suppressed (Target_Typ)
1735 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
1739 -- Check expression itself if it is an entity name
1741 elsif Is_Entity_Name (Expr)
1742 and then Range_Checks_Suppressed (Entity (Expr))
1746 -- If Expr is part of an assignment statement, then check left
1747 -- side of assignment if it is an entity name.
1749 elsif Nkind (Parnt) = N_Assignment_Statement
1750 and then Is_Entity_Name (Name (Parnt))
1751 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
1758 -- Do not set range checks if they are killed
1760 if Nkind (Expr) = N_Unchecked_Type_Conversion
1761 and then Kill_Range_Check (Expr)
1766 -- Do not set range checks for any values from System.Scalar_Values
1767 -- since the whole idea of such values is to avoid checking them!
1769 if Is_Entity_Name (Expr)
1770 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
1775 -- Now see if we need a check
1777 if No (Source_Typ) then
1778 S_Typ := Etype (Expr);
1780 S_Typ := Source_Typ;
1783 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
1787 Is_Unconstrained_Subscr_Ref :=
1788 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
1790 -- Always do a range check if the source type includes infinities and
1791 -- the target type does not include infinities. We do not do this if
1792 -- range checks are killed.
1794 if Is_Floating_Point_Type (S_Typ)
1795 and then Has_Infinities (S_Typ)
1796 and then not Has_Infinities (Target_Typ)
1798 Enable_Range_Check (Expr);
1801 -- Return if we know expression is definitely in the range of the target
1802 -- type as determined by Determine_Range. Right now we only do this for
1803 -- discrete types, and not fixed-point or floating-point types.
1805 -- The additional less-precise tests below catch these cases
1807 -- Note: skip this if we are given a source_typ, since the point of
1808 -- supplying a Source_Typ is to stop us looking at the expression.
1809 -- We could sharpen this test to be out parameters only ???
1811 if Is_Discrete_Type (Target_Typ)
1812 and then Is_Discrete_Type (Etype (Expr))
1813 and then not Is_Unconstrained_Subscr_Ref
1814 and then No (Source_Typ)
1817 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
1818 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
1823 if Compile_Time_Known_Value (Tlo)
1824 and then Compile_Time_Known_Value (Thi)
1827 Lov : constant Uint := Expr_Value (Tlo);
1828 Hiv : constant Uint := Expr_Value (Thi);
1831 -- If range is null, we for sure have a constraint error
1832 -- (we don't even need to look at the value involved,
1833 -- since all possible values will raise CE).
1840 -- Otherwise determine range of value
1842 Determine_Range (Expr, OK, Lo, Hi);
1846 -- If definitely in range, all OK
1848 if Lo >= Lov and then Hi <= Hiv then
1851 -- If definitely not in range, warn
1853 elsif Lov > Hi or else Hiv < Lo then
1857 -- Otherwise we don't know
1869 Is_Floating_Point_Type (S_Typ)
1870 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
1872 -- Check if we can determine at compile time whether Expr is in the
1873 -- range of the target type. Note that if S_Typ is within the bounds
1874 -- of Target_Typ then this must be the case. This check is meaningful
1875 -- only if this is not a conversion between integer and real types.
1877 if not Is_Unconstrained_Subscr_Ref
1879 Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
1881 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
1883 Is_In_Range (Expr, Target_Typ, Fixed_Int, Int_Real))
1887 elsif Is_Out_Of_Range (Expr, Target_Typ, Fixed_Int, Int_Real) then
1891 -- In the floating-point case, we only do range checks if the type is
1892 -- constrained. We definitely do NOT want range checks for unconstrained
1893 -- types, since we want to have infinities
1895 elsif Is_Floating_Point_Type (S_Typ) then
1896 if Is_Constrained (S_Typ) then
1897 Enable_Range_Check (Expr);
1900 -- For all other cases we enable a range check unconditionally
1903 Enable_Range_Check (Expr);
1906 end Apply_Scalar_Range_Check;
1908 ----------------------------------
1909 -- Apply_Selected_Length_Checks --
1910 ----------------------------------
1912 procedure Apply_Selected_Length_Checks
1914 Target_Typ : Entity_Id;
1915 Source_Typ : Entity_Id;
1916 Do_Static : Boolean)
1919 R_Result : Check_Result;
1922 Loc : constant Source_Ptr := Sloc (Ck_Node);
1923 Checks_On : constant Boolean :=
1924 (not Index_Checks_Suppressed (Target_Typ))
1926 (not Length_Checks_Suppressed (Target_Typ));
1929 if not Expander_Active then
1934 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
1936 for J in 1 .. 2 loop
1937 R_Cno := R_Result (J);
1938 exit when No (R_Cno);
1940 -- A length check may mention an Itype which is attached to a
1941 -- subsequent node. At the top level in a package this can cause
1942 -- an order-of-elaboration problem, so we make sure that the itype
1943 -- is referenced now.
1945 if Ekind (Current_Scope) = E_Package
1946 and then Is_Compilation_Unit (Current_Scope)
1948 Ensure_Defined (Target_Typ, Ck_Node);
1950 if Present (Source_Typ) then
1951 Ensure_Defined (Source_Typ, Ck_Node);
1953 elsif Is_Itype (Etype (Ck_Node)) then
1954 Ensure_Defined (Etype (Ck_Node), Ck_Node);
1958 -- If the item is a conditional raise of constraint error, then have
1959 -- a look at what check is being performed and ???
1961 if Nkind (R_Cno) = N_Raise_Constraint_Error
1962 and then Present (Condition (R_Cno))
1964 Cond := Condition (R_Cno);
1966 -- Case where node does not now have a dynamic check
1968 if not Has_Dynamic_Length_Check (Ck_Node) then
1970 -- If checks are on, just insert the check
1973 Insert_Action (Ck_Node, R_Cno);
1975 if not Do_Static then
1976 Set_Has_Dynamic_Length_Check (Ck_Node);
1979 -- If checks are off, then analyze the length check after
1980 -- temporarily attaching it to the tree in case the relevant
1981 -- condition can be evaluted at compile time. We still want a
1982 -- compile time warning in this case.
1985 Set_Parent (R_Cno, Ck_Node);
1990 -- Output a warning if the condition is known to be True
1992 if Is_Entity_Name (Cond)
1993 and then Entity (Cond) = Standard_True
1995 Apply_Compile_Time_Constraint_Error
1996 (Ck_Node, "wrong length for array of}?",
1997 CE_Length_Check_Failed,
2001 -- If we were only doing a static check, or if checks are not
2002 -- on, then we want to delete the check, since it is not needed.
2003 -- We do this by replacing the if statement by a null statement
2005 elsif Do_Static or else not Checks_On then
2006 Remove_Warning_Messages (R_Cno);
2007 Rewrite (R_Cno, Make_Null_Statement (Loc));
2011 Install_Static_Check (R_Cno, Loc);
2014 end Apply_Selected_Length_Checks;
2016 ---------------------------------
2017 -- Apply_Selected_Range_Checks --
2018 ---------------------------------
2020 procedure Apply_Selected_Range_Checks
2022 Target_Typ : Entity_Id;
2023 Source_Typ : Entity_Id;
2024 Do_Static : Boolean)
2027 R_Result : Check_Result;
2030 Loc : constant Source_Ptr := Sloc (Ck_Node);
2031 Checks_On : constant Boolean :=
2032 (not Index_Checks_Suppressed (Target_Typ))
2034 (not Range_Checks_Suppressed (Target_Typ));
2037 if not Expander_Active or else not Checks_On then
2042 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2044 for J in 1 .. 2 loop
2046 R_Cno := R_Result (J);
2047 exit when No (R_Cno);
2049 -- If the item is a conditional raise of constraint error, then have
2050 -- a look at what check is being performed and ???
2052 if Nkind (R_Cno) = N_Raise_Constraint_Error
2053 and then Present (Condition (R_Cno))
2055 Cond := Condition (R_Cno);
2057 if not Has_Dynamic_Range_Check (Ck_Node) then
2058 Insert_Action (Ck_Node, R_Cno);
2060 if not Do_Static then
2061 Set_Has_Dynamic_Range_Check (Ck_Node);
2065 -- Output a warning if the condition is known to be True
2067 if Is_Entity_Name (Cond)
2068 and then Entity (Cond) = Standard_True
2070 -- Since an N_Range is technically not an expression, we have
2071 -- to set one of the bounds to C_E and then just flag the
2072 -- N_Range. The warning message will point to the lower bound
2073 -- and complain about a range, which seems OK.
2075 if Nkind (Ck_Node) = N_Range then
2076 Apply_Compile_Time_Constraint_Error
2077 (Low_Bound (Ck_Node), "static range out of bounds of}?",
2078 CE_Range_Check_Failed,
2082 Set_Raises_Constraint_Error (Ck_Node);
2085 Apply_Compile_Time_Constraint_Error
2086 (Ck_Node, "static value out of range of}?",
2087 CE_Range_Check_Failed,
2092 -- If we were only doing a static check, or if checks are not
2093 -- on, then we want to delete the check, since it is not needed.
2094 -- We do this by replacing the if statement by a null statement
2096 elsif Do_Static or else not Checks_On then
2097 Remove_Warning_Messages (R_Cno);
2098 Rewrite (R_Cno, Make_Null_Statement (Loc));
2102 Install_Static_Check (R_Cno, Loc);
2105 end Apply_Selected_Range_Checks;
2107 -------------------------------
2108 -- Apply_Static_Length_Check --
2109 -------------------------------
2111 procedure Apply_Static_Length_Check
2113 Target_Typ : Entity_Id;
2114 Source_Typ : Entity_Id := Empty)
2117 Apply_Selected_Length_Checks
2118 (Expr, Target_Typ, Source_Typ, Do_Static => True);
2119 end Apply_Static_Length_Check;
2121 -------------------------------------
2122 -- Apply_Subscript_Validity_Checks --
2123 -------------------------------------
2125 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
2129 pragma Assert (Nkind (Expr) = N_Indexed_Component);
2131 -- Loop through subscripts
2133 Sub := First (Expressions (Expr));
2134 while Present (Sub) loop
2136 -- Check one subscript. Note that we do not worry about enumeration
2137 -- type with holes, since we will convert the value to a Pos value
2138 -- for the subscript, and that convert will do the necessary validity
2141 Ensure_Valid (Sub, Holes_OK => True);
2143 -- Move to next subscript
2147 end Apply_Subscript_Validity_Checks;
2149 ----------------------------------
2150 -- Apply_Type_Conversion_Checks --
2151 ----------------------------------
2153 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
2154 Target_Type : constant Entity_Id := Etype (N);
2155 Target_Base : constant Entity_Id := Base_Type (Target_Type);
2156 Expr : constant Node_Id := Expression (N);
2157 Expr_Type : constant Entity_Id := Etype (Expr);
2160 if Inside_A_Generic then
2163 -- Skip these checks if serious errors detected, there are some nasty
2164 -- situations of incomplete trees that blow things up.
2166 elsif Serious_Errors_Detected > 0 then
2169 -- Scalar type conversions of the form Target_Type (Expr) require a
2170 -- range check if we cannot be sure that Expr is in the base type of
2171 -- Target_Typ and also that Expr is in the range of Target_Typ. These
2172 -- are not quite the same condition from an implementation point of
2173 -- view, but clearly the second includes the first.
2175 elsif Is_Scalar_Type (Target_Type) then
2177 Conv_OK : constant Boolean := Conversion_OK (N);
2178 -- If the Conversion_OK flag on the type conversion is set and no
2179 -- floating point type is involved in the type conversion then
2180 -- fixed point values must be read as integral values.
2182 Float_To_Int : constant Boolean :=
2183 Is_Floating_Point_Type (Expr_Type)
2184 and then Is_Integer_Type (Target_Type);
2187 if not Overflow_Checks_Suppressed (Target_Base)
2188 and then not In_Subrange_Of (Expr_Type, Target_Base, Conv_OK)
2189 and then not Float_To_Int
2191 Activate_Overflow_Check (N);
2194 if not Range_Checks_Suppressed (Target_Type)
2195 and then not Range_Checks_Suppressed (Expr_Type)
2197 if Float_To_Int then
2198 Apply_Float_Conversion_Check (Expr, Target_Type);
2200 Apply_Scalar_Range_Check
2201 (Expr, Target_Type, Fixed_Int => Conv_OK);
2206 elsif Comes_From_Source (N)
2207 and then Is_Record_Type (Target_Type)
2208 and then Is_Derived_Type (Target_Type)
2209 and then not Is_Tagged_Type (Target_Type)
2210 and then not Is_Constrained (Target_Type)
2211 and then Present (Stored_Constraint (Target_Type))
2213 -- An unconstrained derived type may have inherited discriminant
2214 -- Build an actual discriminant constraint list using the stored
2215 -- constraint, to verify that the expression of the parent type
2216 -- satisfies the constraints imposed by the (unconstrained!)
2217 -- derived type. This applies to value conversions, not to view
2218 -- conversions of tagged types.
2221 Loc : constant Source_Ptr := Sloc (N);
2223 Constraint : Elmt_Id;
2224 Discr_Value : Node_Id;
2227 New_Constraints : constant Elist_Id := New_Elmt_List;
2228 Old_Constraints : constant Elist_Id :=
2229 Discriminant_Constraint (Expr_Type);
2232 Constraint := First_Elmt (Stored_Constraint (Target_Type));
2233 while Present (Constraint) loop
2234 Discr_Value := Node (Constraint);
2236 if Is_Entity_Name (Discr_Value)
2237 and then Ekind (Entity (Discr_Value)) = E_Discriminant
2239 Discr := Corresponding_Discriminant (Entity (Discr_Value));
2242 and then Scope (Discr) = Base_Type (Expr_Type)
2244 -- Parent is constrained by new discriminant. Obtain
2245 -- Value of original discriminant in expression. If the
2246 -- new discriminant has been used to constrain more than
2247 -- one of the stored discriminants, this will provide the
2248 -- required consistency check.
2251 Make_Selected_Component (Loc,
2253 Duplicate_Subexpr_No_Checks
2254 (Expr, Name_Req => True),
2256 Make_Identifier (Loc, Chars (Discr))),
2260 -- Discriminant of more remote ancestor ???
2265 -- Derived type definition has an explicit value for this
2266 -- stored discriminant.
2270 (Duplicate_Subexpr_No_Checks (Discr_Value),
2274 Next_Elmt (Constraint);
2277 -- Use the unconstrained expression type to retrieve the
2278 -- discriminants of the parent, and apply momentarily the
2279 -- discriminant constraint synthesized above.
2281 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
2282 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
2283 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
2286 Make_Raise_Constraint_Error (Loc,
2288 Reason => CE_Discriminant_Check_Failed));
2291 -- For arrays, conversions are applied during expansion, to take into
2292 -- accounts changes of representation. The checks become range checks on
2293 -- the base type or length checks on the subtype, depending on whether
2294 -- the target type is unconstrained or constrained.
2299 end Apply_Type_Conversion_Checks;
2301 ----------------------------------------------
2302 -- Apply_Universal_Integer_Attribute_Checks --
2303 ----------------------------------------------
2305 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
2306 Loc : constant Source_Ptr := Sloc (N);
2307 Typ : constant Entity_Id := Etype (N);
2310 if Inside_A_Generic then
2313 -- Nothing to do if checks are suppressed
2315 elsif Range_Checks_Suppressed (Typ)
2316 and then Overflow_Checks_Suppressed (Typ)
2320 -- Nothing to do if the attribute does not come from source. The
2321 -- internal attributes we generate of this type do not need checks,
2322 -- and furthermore the attempt to check them causes some circular
2323 -- elaboration orders when dealing with packed types.
2325 elsif not Comes_From_Source (N) then
2328 -- If the prefix is a selected component that depends on a discriminant
2329 -- the check may improperly expose a discriminant instead of using
2330 -- the bounds of the object itself. Set the type of the attribute to
2331 -- the base type of the context, so that a check will be imposed when
2332 -- needed (e.g. if the node appears as an index).
2334 elsif Nkind (Prefix (N)) = N_Selected_Component
2335 and then Ekind (Typ) = E_Signed_Integer_Subtype
2336 and then Depends_On_Discriminant (Scalar_Range (Typ))
2338 Set_Etype (N, Base_Type (Typ));
2340 -- Otherwise, replace the attribute node with a type conversion node
2341 -- whose expression is the attribute, retyped to universal integer, and
2342 -- whose subtype mark is the target type. The call to analyze this
2343 -- conversion will set range and overflow checks as required for proper
2344 -- detection of an out of range value.
2347 Set_Etype (N, Universal_Integer);
2348 Set_Analyzed (N, True);
2351 Make_Type_Conversion (Loc,
2352 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
2353 Expression => Relocate_Node (N)));
2355 Analyze_And_Resolve (N, Typ);
2359 end Apply_Universal_Integer_Attribute_Checks;
2361 -------------------------------
2362 -- Build_Discriminant_Checks --
2363 -------------------------------
2365 function Build_Discriminant_Checks
2367 T_Typ : Entity_Id) return Node_Id
2369 Loc : constant Source_Ptr := Sloc (N);
2372 Disc_Ent : Entity_Id;
2376 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
2378 ----------------------------------
2379 -- Aggregate_Discriminant_Value --
2380 ----------------------------------
2382 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
2386 -- The aggregate has been normalized with named associations. We use
2387 -- the Chars field to locate the discriminant to take into account
2388 -- discriminants in derived types, which carry the same name as those
2391 Assoc := First (Component_Associations (N));
2392 while Present (Assoc) loop
2393 if Chars (First (Choices (Assoc))) = Chars (Disc) then
2394 return Expression (Assoc);
2400 -- Discriminant must have been found in the loop above
2402 raise Program_Error;
2403 end Aggregate_Discriminant_Val;
2405 -- Start of processing for Build_Discriminant_Checks
2408 -- Loop through discriminants evolving the condition
2411 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
2413 -- For a fully private type, use the discriminants of the parent type
2415 if Is_Private_Type (T_Typ)
2416 and then No (Full_View (T_Typ))
2418 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
2420 Disc_Ent := First_Discriminant (T_Typ);
2423 while Present (Disc) loop
2424 Dval := Node (Disc);
2426 if Nkind (Dval) = N_Identifier
2427 and then Ekind (Entity (Dval)) = E_Discriminant
2429 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
2431 Dval := Duplicate_Subexpr_No_Checks (Dval);
2434 -- If we have an Unchecked_Union node, we can infer the discriminants
2437 if Is_Unchecked_Union (Base_Type (T_Typ)) then
2439 Get_Discriminant_Value (
2440 First_Discriminant (T_Typ),
2442 Stored_Constraint (T_Typ)));
2444 elsif Nkind (N) = N_Aggregate then
2446 Duplicate_Subexpr_No_Checks
2447 (Aggregate_Discriminant_Val (Disc_Ent));
2451 Make_Selected_Component (Loc,
2453 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
2455 Make_Identifier (Loc, Chars (Disc_Ent)));
2457 Set_Is_In_Discriminant_Check (Dref);
2460 Evolve_Or_Else (Cond,
2463 Right_Opnd => Dval));
2466 Next_Discriminant (Disc_Ent);
2470 end Build_Discriminant_Checks;
2476 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
2484 -- Always check if not simple entity
2486 if Nkind (Nod) not in N_Has_Entity
2487 or else not Comes_From_Source (Nod)
2492 -- Look up tree for short circuit
2499 if K not in N_Subexpr then
2502 -- Or/Or Else case, left operand must be equality test
2504 elsif K = N_Op_Or or else K = N_Or_Else then
2505 exit when N = Right_Opnd (P)
2506 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2508 -- And/And then case, left operand must be inequality test
2510 elsif K = N_Op_And or else K = N_And_Then then
2511 exit when N = Right_Opnd (P)
2512 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2518 -- If we fall through the loop, then we have a conditional with an
2519 -- appropriate test as its left operand. So test further.
2523 if Nkind (L) = N_Op_Not then
2524 L := Right_Opnd (L);
2527 R := Right_Opnd (L);
2530 -- Left operand of test must match original variable
2532 if Nkind (L) not in N_Has_Entity
2533 or else Entity (L) /= Entity (Nod)
2538 -- Right operand of test must be key value (zero or null)
2541 when Access_Check =>
2542 if not Known_Null (R) then
2546 when Division_Check =>
2547 if not Compile_Time_Known_Value (R)
2548 or else Expr_Value (R) /= Uint_0
2554 raise Program_Error;
2557 -- Here we have the optimizable case, warn if not short-circuited
2559 if K = N_Op_And or else K = N_Op_Or then
2561 when Access_Check =>
2563 ("Constraint_Error may be raised (access check)?",
2565 when Division_Check =>
2567 ("Constraint_Error may be raised (zero divide)?",
2571 raise Program_Error;
2574 if K = N_Op_And then
2575 Error_Msg_N ("use `AND THEN` instead of AND?", P);
2577 Error_Msg_N ("use `OR ELSE` instead of OR?", P);
2580 -- If not short-circuited, we need the ckeck
2584 -- If short-circuited, we can omit the check
2591 -----------------------------------
2592 -- Check_Valid_Lvalue_Subscripts --
2593 -----------------------------------
2595 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
2597 -- Skip this if range checks are suppressed
2599 if Range_Checks_Suppressed (Etype (Expr)) then
2602 -- Only do this check for expressions that come from source. We assume
2603 -- that expander generated assignments explicitly include any necessary
2604 -- checks. Note that this is not just an optimization, it avoids
2605 -- infinite recursions!
2607 elsif not Comes_From_Source (Expr) then
2610 -- For a selected component, check the prefix
2612 elsif Nkind (Expr) = N_Selected_Component then
2613 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2616 -- Case of indexed component
2618 elsif Nkind (Expr) = N_Indexed_Component then
2619 Apply_Subscript_Validity_Checks (Expr);
2621 -- Prefix may itself be or contain an indexed component, and these
2622 -- subscripts need checking as well.
2624 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2626 end Check_Valid_Lvalue_Subscripts;
2628 ----------------------------------
2629 -- Null_Exclusion_Static_Checks --
2630 ----------------------------------
2632 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
2633 Error_Node : Node_Id;
2635 Has_Null : constant Boolean := Has_Null_Exclusion (N);
2636 K : constant Node_Kind := Nkind (N);
2641 (K = N_Component_Declaration
2642 or else K = N_Discriminant_Specification
2643 or else K = N_Function_Specification
2644 or else K = N_Object_Declaration
2645 or else K = N_Parameter_Specification);
2647 if K = N_Function_Specification then
2648 Typ := Etype (Defining_Entity (N));
2650 Typ := Etype (Defining_Identifier (N));
2654 when N_Component_Declaration =>
2655 if Present (Access_Definition (Component_Definition (N))) then
2656 Error_Node := Component_Definition (N);
2658 Error_Node := Subtype_Indication (Component_Definition (N));
2661 when N_Discriminant_Specification =>
2662 Error_Node := Discriminant_Type (N);
2664 when N_Function_Specification =>
2665 Error_Node := Result_Definition (N);
2667 when N_Object_Declaration =>
2668 Error_Node := Object_Definition (N);
2670 when N_Parameter_Specification =>
2671 Error_Node := Parameter_Type (N);
2674 raise Program_Error;
2679 -- Enforce legality rule 3.10 (13): A null exclusion can only be
2680 -- applied to an access [sub]type.
2682 if not Is_Access_Type (Typ) then
2684 ("`NOT NULL` allowed only for an access type", Error_Node);
2686 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
2687 -- be applied to a [sub]type that does not exclude null already.
2689 elsif Can_Never_Be_Null (Typ)
2691 -- No need to check itypes that have a null exclusion because
2692 -- they are already examined at their point of creation.
2694 and then not Is_Itype (Typ)
2697 ("`NOT NULL` not allowed (& already excludes null)",
2702 -- Check that null-excluding objects are always initialized
2704 if K = N_Object_Declaration
2705 and then No (Expression (N))
2706 and then not No_Initialization (N)
2708 -- Add an expression that assigns null. This node is needed by
2709 -- Apply_Compile_Time_Constraint_Error, which will replace this with
2710 -- a Constraint_Error node.
2712 Set_Expression (N, Make_Null (Sloc (N)));
2713 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
2715 Apply_Compile_Time_Constraint_Error
2716 (N => Expression (N),
2717 Msg => "(Ada 2005) null-excluding objects must be initialized?",
2718 Reason => CE_Null_Not_Allowed);
2721 -- Check that a null-excluding component, formal or object is not
2722 -- being assigned a null value. Otherwise generate a warning message
2723 -- and replace Expression (N) by a N_Contraint_Error node.
2725 if K /= N_Function_Specification then
2726 Expr := Expression (N);
2728 if Present (Expr) and then Known_Null (Expr) then
2730 when N_Component_Declaration |
2731 N_Discriminant_Specification =>
2732 Apply_Compile_Time_Constraint_Error
2734 Msg => "(Ada 2005) null not allowed " &
2735 "in null-excluding components?",
2736 Reason => CE_Null_Not_Allowed);
2738 when N_Object_Declaration =>
2739 Apply_Compile_Time_Constraint_Error
2741 Msg => "(Ada 2005) null not allowed " &
2742 "in null-excluding objects?",
2743 Reason => CE_Null_Not_Allowed);
2745 when N_Parameter_Specification =>
2746 Apply_Compile_Time_Constraint_Error
2748 Msg => "(Ada 2005) null not allowed " &
2749 "in null-excluding formals?",
2750 Reason => CE_Null_Not_Allowed);
2757 end Null_Exclusion_Static_Checks;
2759 ----------------------------------
2760 -- Conditional_Statements_Begin --
2761 ----------------------------------
2763 procedure Conditional_Statements_Begin is
2765 Saved_Checks_TOS := Saved_Checks_TOS + 1;
2767 -- If stack overflows, kill all checks, that way we know to simply reset
2768 -- the number of saved checks to zero on return. This should never occur
2771 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2774 -- In the normal case, we just make a new stack entry saving the current
2775 -- number of saved checks for a later restore.
2778 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
2780 if Debug_Flag_CC then
2781 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
2785 end Conditional_Statements_Begin;
2787 --------------------------------
2788 -- Conditional_Statements_End --
2789 --------------------------------
2791 procedure Conditional_Statements_End is
2793 pragma Assert (Saved_Checks_TOS > 0);
2795 -- If the saved checks stack overflowed, then we killed all checks, so
2796 -- setting the number of saved checks back to zero is correct. This
2797 -- should never occur in practice.
2799 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2800 Num_Saved_Checks := 0;
2802 -- In the normal case, restore the number of saved checks from the top
2806 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
2807 if Debug_Flag_CC then
2808 w ("Conditional_Statements_End: Num_Saved_Checks = ",
2813 Saved_Checks_TOS := Saved_Checks_TOS - 1;
2814 end Conditional_Statements_End;
2816 ---------------------
2817 -- Determine_Range --
2818 ---------------------
2820 Cache_Size : constant := 2 ** 10;
2821 type Cache_Index is range 0 .. Cache_Size - 1;
2822 -- Determine size of below cache (power of 2 is more efficient!)
2824 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
2825 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
2826 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
2827 -- The above arrays are used to implement a small direct cache for
2828 -- Determine_Range calls. Because of the way Determine_Range recursively
2829 -- traces subexpressions, and because overflow checking calls the routine
2830 -- on the way up the tree, a quadratic behavior can otherwise be
2831 -- encountered in large expressions. The cache entry for node N is stored
2832 -- in the (N mod Cache_Size) entry, and can be validated by checking the
2833 -- actual node value stored there.
2835 procedure Determine_Range
2841 Typ : constant Entity_Id := Etype (N);
2845 -- Lo and Hi bounds of left operand
2849 -- Lo and Hi bounds of right (or only) operand
2852 -- Temp variable used to hold a bound node
2855 -- High bound of base type of expression
2859 -- Refined values for low and high bounds, after tightening
2862 -- Used in lower level calls to indicate if call succeeded
2864 Cindex : Cache_Index;
2865 -- Used to search cache
2867 function OK_Operands return Boolean;
2868 -- Used for binary operators. Determines the ranges of the left and
2869 -- right operands, and if they are both OK, returns True, and puts
2870 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left
2876 function OK_Operands return Boolean is
2878 Determine_Range (Left_Opnd (N), OK1, Lo_Left, Hi_Left);
2884 Determine_Range (Right_Opnd (N), OK1, Lo_Right, Hi_Right);
2888 -- Start of processing for Determine_Range
2891 -- Prevent junk warnings by initializing range variables
2898 -- If the type is not discrete, or is undefined, then we can't do
2899 -- anything about determining the range.
2901 if No (Typ) or else not Is_Discrete_Type (Typ)
2902 or else Error_Posted (N)
2908 -- For all other cases, we can determine the range
2912 -- If value is compile time known, then the possible range is the one
2913 -- value that we know this expression definitely has!
2915 if Compile_Time_Known_Value (N) then
2916 Lo := Expr_Value (N);
2921 -- Return if already in the cache
2923 Cindex := Cache_Index (N mod Cache_Size);
2925 if Determine_Range_Cache_N (Cindex) = N then
2926 Lo := Determine_Range_Cache_Lo (Cindex);
2927 Hi := Determine_Range_Cache_Hi (Cindex);
2931 -- Otherwise, start by finding the bounds of the type of the expression,
2932 -- the value cannot be outside this range (if it is, then we have an
2933 -- overflow situation, which is a separate check, we are talking here
2934 -- only about the expression value).
2936 -- We use the actual bound unless it is dynamic, in which case use the
2937 -- corresponding base type bound if possible. If we can't get a bound
2938 -- then we figure we can't determine the range (a peculiar case, that
2939 -- perhaps cannot happen, but there is no point in bombing in this
2940 -- optimization circuit.
2942 -- First the low bound
2944 Bound := Type_Low_Bound (Typ);
2946 if Compile_Time_Known_Value (Bound) then
2947 Lo := Expr_Value (Bound);
2949 elsif Compile_Time_Known_Value (Type_Low_Bound (Base_Type (Typ))) then
2950 Lo := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
2957 -- Now the high bound
2959 Bound := Type_High_Bound (Typ);
2961 -- We need the high bound of the base type later on, and this should
2962 -- always be compile time known. Again, it is not clear that this
2963 -- can ever be false, but no point in bombing.
2965 if Compile_Time_Known_Value (Type_High_Bound (Base_Type (Typ))) then
2966 Hbound := Expr_Value (Type_High_Bound (Base_Type (Typ)));
2974 -- If we have a static subtype, then that may have a tighter bound so
2975 -- use the upper bound of the subtype instead in this case.
2977 if Compile_Time_Known_Value (Bound) then
2978 Hi := Expr_Value (Bound);
2981 -- We may be able to refine this value in certain situations. If any
2982 -- refinement is possible, then Lor and Hir are set to possibly tighter
2983 -- bounds, and OK1 is set to True.
2987 -- For unary plus, result is limited by range of operand
2990 Determine_Range (Right_Opnd (N), OK1, Lor, Hir);
2992 -- For unary minus, determine range of operand, and negate it
2995 Determine_Range (Right_Opnd (N), OK1, Lo_Right, Hi_Right);
3002 -- For binary addition, get range of each operand and do the
3003 -- addition to get the result range.
3007 Lor := Lo_Left + Lo_Right;
3008 Hir := Hi_Left + Hi_Right;
3011 -- Division is tricky. The only case we consider is where the right
3012 -- operand is a positive constant, and in this case we simply divide
3013 -- the bounds of the left operand
3017 if Lo_Right = Hi_Right
3018 and then Lo_Right > 0
3020 Lor := Lo_Left / Lo_Right;
3021 Hir := Hi_Left / Lo_Right;
3028 -- For binary subtraction, get range of each operand and do the worst
3029 -- case subtraction to get the result range.
3031 when N_Op_Subtract =>
3033 Lor := Lo_Left - Hi_Right;
3034 Hir := Hi_Left - Lo_Right;
3037 -- For MOD, if right operand is a positive constant, then result must
3038 -- be in the allowable range of mod results.
3042 if Lo_Right = Hi_Right
3043 and then Lo_Right /= 0
3045 if Lo_Right > 0 then
3047 Hir := Lo_Right - 1;
3049 else -- Lo_Right < 0
3050 Lor := Lo_Right + 1;
3059 -- For REM, if right operand is a positive constant, then result must
3060 -- be in the allowable range of mod results.
3064 if Lo_Right = Hi_Right
3065 and then Lo_Right /= 0
3068 Dval : constant Uint := (abs Lo_Right) - 1;
3071 -- The sign of the result depends on the sign of the
3072 -- dividend (but not on the sign of the divisor, hence
3073 -- the abs operation above).
3093 -- Attribute reference cases
3095 when N_Attribute_Reference =>
3096 case Attribute_Name (N) is
3098 -- For Pos/Val attributes, we can refine the range using the
3099 -- possible range of values of the attribute expression
3101 when Name_Pos | Name_Val =>
3102 Determine_Range (First (Expressions (N)), OK1, Lor, Hir);
3104 -- For Length attribute, use the bounds of the corresponding
3105 -- index type to refine the range.
3109 Atyp : Entity_Id := Etype (Prefix (N));
3117 if Is_Access_Type (Atyp) then
3118 Atyp := Designated_Type (Atyp);
3121 -- For string literal, we know exact value
3123 if Ekind (Atyp) = E_String_Literal_Subtype then
3125 Lo := String_Literal_Length (Atyp);
3126 Hi := String_Literal_Length (Atyp);
3130 -- Otherwise check for expression given
3132 if No (Expressions (N)) then
3136 UI_To_Int (Expr_Value (First (Expressions (N))));
3139 Indx := First_Index (Atyp);
3140 for J in 2 .. Inum loop
3141 Indx := Next_Index (Indx);
3145 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU);
3149 (Type_High_Bound (Etype (Indx)), OK1, UL, UU);
3153 -- The maximum value for Length is the biggest
3154 -- possible gap between the values of the bounds.
3155 -- But of course, this value cannot be negative.
3157 Hir := UI_Max (Uint_0, UU - LL);
3159 -- For constrained arrays, the minimum value for
3160 -- Length is taken from the actual value of the
3161 -- bounds, since the index will be exactly of
3164 if Is_Constrained (Atyp) then
3165 Lor := UI_Max (Uint_0, UL - LU);
3167 -- For an unconstrained array, the minimum value
3168 -- for length is always zero.
3177 -- No special handling for other attributes
3178 -- Probably more opportunities exist here ???
3185 -- For type conversion from one discrete type to another, we can
3186 -- refine the range using the converted value.
3188 when N_Type_Conversion =>
3189 Determine_Range (Expression (N), OK1, Lor, Hir);
3191 -- Nothing special to do for all other expression kinds
3199 -- At this stage, if OK1 is true, then we know that the actual
3200 -- result of the computed expression is in the range Lor .. Hir.
3201 -- We can use this to restrict the possible range of results.
3205 -- If the refined value of the low bound is greater than the
3206 -- type high bound, then reset it to the more restrictive
3207 -- value. However, we do NOT do this for the case of a modular
3208 -- type where the possible upper bound on the value is above the
3209 -- base type high bound, because that means the result could wrap.
3212 and then not (Is_Modular_Integer_Type (Typ)
3213 and then Hir > Hbound)
3218 -- Similarly, if the refined value of the high bound is less
3219 -- than the value so far, then reset it to the more restrictive
3220 -- value. Again, we do not do this if the refined low bound is
3221 -- negative for a modular type, since this would wrap.
3224 and then not (Is_Modular_Integer_Type (Typ)
3225 and then Lor < Uint_0)
3231 -- Set cache entry for future call and we are all done
3233 Determine_Range_Cache_N (Cindex) := N;
3234 Determine_Range_Cache_Lo (Cindex) := Lo;
3235 Determine_Range_Cache_Hi (Cindex) := Hi;
3238 -- If any exception occurs, it means that we have some bug in the compiler
3239 -- possibly triggered by a previous error, or by some unforseen peculiar
3240 -- occurrence. However, this is only an optimization attempt, so there is
3241 -- really no point in crashing the compiler. Instead we just decide, too
3242 -- bad, we can't figure out a range in this case after all.
3247 -- Debug flag K disables this behavior (useful for debugging)
3249 if Debug_Flag_K then
3257 end Determine_Range;
3259 ------------------------------------
3260 -- Discriminant_Checks_Suppressed --
3261 ------------------------------------
3263 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
3266 if Is_Unchecked_Union (E) then
3268 elsif Checks_May_Be_Suppressed (E) then
3269 return Is_Check_Suppressed (E, Discriminant_Check);
3273 return Scope_Suppress (Discriminant_Check);
3274 end Discriminant_Checks_Suppressed;
3276 --------------------------------
3277 -- Division_Checks_Suppressed --
3278 --------------------------------
3280 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
3282 if Present (E) and then Checks_May_Be_Suppressed (E) then
3283 return Is_Check_Suppressed (E, Division_Check);
3285 return Scope_Suppress (Division_Check);
3287 end Division_Checks_Suppressed;
3289 -----------------------------------
3290 -- Elaboration_Checks_Suppressed --
3291 -----------------------------------
3293 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
3295 -- The complication in this routine is that if we are in the dynamic
3296 -- model of elaboration, we also check All_Checks, since All_Checks
3297 -- does not set Elaboration_Check explicitly.
3300 if Kill_Elaboration_Checks (E) then
3303 elsif Checks_May_Be_Suppressed (E) then
3304 if Is_Check_Suppressed (E, Elaboration_Check) then
3306 elsif Dynamic_Elaboration_Checks then
3307 return Is_Check_Suppressed (E, All_Checks);
3314 if Scope_Suppress (Elaboration_Check) then
3316 elsif Dynamic_Elaboration_Checks then
3317 return Scope_Suppress (All_Checks);
3321 end Elaboration_Checks_Suppressed;
3323 ---------------------------
3324 -- Enable_Overflow_Check --
3325 ---------------------------
3327 procedure Enable_Overflow_Check (N : Node_Id) is
3328 Typ : constant Entity_Id := Base_Type (Etype (N));
3337 if Debug_Flag_CC then
3338 w ("Enable_Overflow_Check for node ", Int (N));
3339 Write_Str (" Source location = ");
3344 -- Nothing to do if the range of the result is known OK. We skip this
3345 -- for conversions, since the caller already did the check, and in any
3346 -- case the condition for deleting the check for a type conversion is
3347 -- different in any case.
3349 if Nkind (N) /= N_Type_Conversion then
3350 Determine_Range (N, OK, Lo, Hi);
3352 -- Note in the test below that we assume that if a bound of the
3353 -- range is equal to that of the type. That's not quite accurate
3354 -- but we do this for the following reasons:
3356 -- a) The way that Determine_Range works, it will typically report
3357 -- the bounds of the value as being equal to the bounds of the
3358 -- type, because it either can't tell anything more precise, or
3359 -- does not think it is worth the effort to be more precise.
3361 -- b) It is very unusual to have a situation in which this would
3362 -- generate an unnecessary overflow check (an example would be
3363 -- a subtype with a range 0 .. Integer'Last - 1 to which the
3364 -- literal value one is added.
3366 -- c) The alternative is a lot of special casing in this routine
3367 -- which would partially duplicate Determine_Range processing.
3370 and then Lo > Expr_Value (Type_Low_Bound (Typ))
3371 and then Hi < Expr_Value (Type_High_Bound (Typ))
3373 if Debug_Flag_CC then
3374 w ("No overflow check required");
3381 -- If not in optimizing mode, set flag and we are done. We are also done
3382 -- (and just set the flag) if the type is not a discrete type, since it
3383 -- is not worth the effort to eliminate checks for other than discrete
3384 -- types. In addition, we take this same path if we have stored the
3385 -- maximum number of checks possible already (a very unlikely situation,
3386 -- but we do not want to blow up!)
3388 if Optimization_Level = 0
3389 or else not Is_Discrete_Type (Etype (N))
3390 or else Num_Saved_Checks = Saved_Checks'Last
3392 Activate_Overflow_Check (N);
3394 if Debug_Flag_CC then
3395 w ("Optimization off");
3401 -- Otherwise evaluate and check the expression
3406 Target_Type => Empty,
3412 if Debug_Flag_CC then
3413 w ("Called Find_Check");
3417 w (" Check_Num = ", Chk);
3418 w (" Ent = ", Int (Ent));
3419 Write_Str (" Ofs = ");
3424 -- If check is not of form to optimize, then set flag and we are done
3427 Activate_Overflow_Check (N);
3431 -- If check is already performed, then return without setting flag
3434 if Debug_Flag_CC then
3435 w ("Check suppressed!");
3441 -- Here we will make a new entry for the new check
3443 Activate_Overflow_Check (N);
3444 Num_Saved_Checks := Num_Saved_Checks + 1;
3445 Saved_Checks (Num_Saved_Checks) :=
3450 Target_Type => Empty);
3452 if Debug_Flag_CC then
3453 w ("Make new entry, check number = ", Num_Saved_Checks);
3454 w (" Entity = ", Int (Ent));
3455 Write_Str (" Offset = ");
3457 w (" Check_Type = O");
3458 w (" Target_Type = Empty");
3461 -- If we get an exception, then something went wrong, probably because of
3462 -- an error in the structure of the tree due to an incorrect program. Or it
3463 -- may be a bug in the optimization circuit. In either case the safest
3464 -- thing is simply to set the check flag unconditionally.
3468 Activate_Overflow_Check (N);
3470 if Debug_Flag_CC then
3471 w (" exception occurred, overflow flag set");
3475 end Enable_Overflow_Check;
3477 ------------------------
3478 -- Enable_Range_Check --
3479 ------------------------
3481 procedure Enable_Range_Check (N : Node_Id) is
3490 -- Return if unchecked type conversion with range check killed. In this
3491 -- case we never set the flag (that's what Kill_Range_Check is about!)
3493 if Nkind (N) = N_Unchecked_Type_Conversion
3494 and then Kill_Range_Check (N)
3499 -- Check for various cases where we should suppress the range check
3501 -- No check if range checks suppressed for type of node
3503 if Present (Etype (N))
3504 and then Range_Checks_Suppressed (Etype (N))
3508 -- No check if node is an entity name, and range checks are suppressed
3509 -- for this entity, or for the type of this entity.
3511 elsif Is_Entity_Name (N)
3512 and then (Range_Checks_Suppressed (Entity (N))
3513 or else Range_Checks_Suppressed (Etype (Entity (N))))
3517 -- No checks if index of array, and index checks are suppressed for
3518 -- the array object or the type of the array.
3520 elsif Nkind (Parent (N)) = N_Indexed_Component then
3522 Pref : constant Node_Id := Prefix (Parent (N));
3524 if Is_Entity_Name (Pref)
3525 and then Index_Checks_Suppressed (Entity (Pref))
3528 elsif Index_Checks_Suppressed (Etype (Pref)) then
3534 -- Debug trace output
3536 if Debug_Flag_CC then
3537 w ("Enable_Range_Check for node ", Int (N));
3538 Write_Str (" Source location = ");
3543 -- If not in optimizing mode, set flag and we are done. We are also done
3544 -- (and just set the flag) if the type is not a discrete type, since it
3545 -- is not worth the effort to eliminate checks for other than discrete
3546 -- types. In addition, we take this same path if we have stored the
3547 -- maximum number of checks possible already (a very unlikely situation,
3548 -- but we do not want to blow up!)
3550 if Optimization_Level = 0
3551 or else No (Etype (N))
3552 or else not Is_Discrete_Type (Etype (N))
3553 or else Num_Saved_Checks = Saved_Checks'Last
3555 Activate_Range_Check (N);
3557 if Debug_Flag_CC then
3558 w ("Optimization off");
3564 -- Otherwise find out the target type
3568 -- For assignment, use left side subtype
3570 if Nkind (P) = N_Assignment_Statement
3571 and then Expression (P) = N
3573 Ttyp := Etype (Name (P));
3575 -- For indexed component, use subscript subtype
3577 elsif Nkind (P) = N_Indexed_Component then
3584 Atyp := Etype (Prefix (P));
3586 if Is_Access_Type (Atyp) then
3587 Atyp := Designated_Type (Atyp);
3589 -- If the prefix is an access to an unconstrained array,
3590 -- perform check unconditionally: it depends on the bounds of
3591 -- an object and we cannot currently recognize whether the test
3592 -- may be redundant.
3594 if not Is_Constrained (Atyp) then
3595 Activate_Range_Check (N);
3599 -- Ditto if the prefix is an explicit dereference whose designated
3600 -- type is unconstrained.
3602 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
3603 and then not Is_Constrained (Atyp)
3605 Activate_Range_Check (N);
3609 Indx := First_Index (Atyp);
3610 Subs := First (Expressions (P));
3613 Ttyp := Etype (Indx);
3622 -- For now, ignore all other cases, they are not so interesting
3625 if Debug_Flag_CC then
3626 w (" target type not found, flag set");
3629 Activate_Range_Check (N);
3633 -- Evaluate and check the expression
3638 Target_Type => Ttyp,
3644 if Debug_Flag_CC then
3645 w ("Called Find_Check");
3646 w ("Target_Typ = ", Int (Ttyp));
3650 w (" Check_Num = ", Chk);
3651 w (" Ent = ", Int (Ent));
3652 Write_Str (" Ofs = ");
3657 -- If check is not of form to optimize, then set flag and we are done
3660 if Debug_Flag_CC then
3661 w (" expression not of optimizable type, flag set");
3664 Activate_Range_Check (N);
3668 -- If check is already performed, then return without setting flag
3671 if Debug_Flag_CC then
3672 w ("Check suppressed!");
3678 -- Here we will make a new entry for the new check
3680 Activate_Range_Check (N);
3681 Num_Saved_Checks := Num_Saved_Checks + 1;
3682 Saved_Checks (Num_Saved_Checks) :=
3687 Target_Type => Ttyp);
3689 if Debug_Flag_CC then
3690 w ("Make new entry, check number = ", Num_Saved_Checks);
3691 w (" Entity = ", Int (Ent));
3692 Write_Str (" Offset = ");
3694 w (" Check_Type = R");
3695 w (" Target_Type = ", Int (Ttyp));
3696 pg (Union_Id (Ttyp));
3699 -- If we get an exception, then something went wrong, probably because of
3700 -- an error in the structure of the tree due to an incorrect program. Or
3701 -- it may be a bug in the optimization circuit. In either case the safest
3702 -- thing is simply to set the check flag unconditionally.
3706 Activate_Range_Check (N);
3708 if Debug_Flag_CC then
3709 w (" exception occurred, range flag set");
3713 end Enable_Range_Check;
3719 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
3720 Typ : constant Entity_Id := Etype (Expr);
3723 -- Ignore call if we are not doing any validity checking
3725 if not Validity_Checks_On then
3728 -- Ignore call if range or validity checks suppressed on entity or type
3730 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
3733 -- No check required if expression is from the expander, we assume the
3734 -- expander will generate whatever checks are needed. Note that this is
3735 -- not just an optimization, it avoids infinite recursions!
3737 -- Unchecked conversions must be checked, unless they are initialized
3738 -- scalar values, as in a component assignment in an init proc.
3740 -- In addition, we force a check if Force_Validity_Checks is set
3742 elsif not Comes_From_Source (Expr)
3743 and then not Force_Validity_Checks
3744 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
3745 or else Kill_Range_Check (Expr))
3749 -- No check required if expression is known to have valid value
3751 elsif Expr_Known_Valid (Expr) then
3754 -- Ignore case of enumeration with holes where the flag is set not to
3755 -- worry about holes, since no special validity check is needed
3757 elsif Is_Enumeration_Type (Typ)
3758 and then Has_Non_Standard_Rep (Typ)
3763 -- No check required on the left-hand side of an assignment
3765 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
3766 and then Expr = Name (Parent (Expr))
3770 -- No check on a univeral real constant. The context will eventually
3771 -- convert it to a machine number for some target type, or report an
3774 elsif Nkind (Expr) = N_Real_Literal
3775 and then Etype (Expr) = Universal_Real
3779 -- If the expression denotes a component of a packed boolean arrray,
3780 -- no possible check applies. We ignore the old ACATS chestnuts that
3781 -- involve Boolean range True..True.
3783 -- Note: validity checks are generated for expressions that yield a
3784 -- scalar type, when it is possible to create a value that is outside of
3785 -- the type. If this is a one-bit boolean no such value exists. This is
3786 -- an optimization, and it also prevents compiler blowing up during the
3787 -- elaboration of improperly expanded packed array references.
3789 elsif Nkind (Expr) = N_Indexed_Component
3790 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
3791 and then Root_Type (Etype (Expr)) = Standard_Boolean
3795 -- An annoying special case. If this is an out parameter of a scalar
3796 -- type, then the value is not going to be accessed, therefore it is
3797 -- inappropriate to do any validity check at the call site.
3800 -- Only need to worry about scalar types
3802 if Is_Scalar_Type (Typ) then
3812 -- Find actual argument (which may be a parameter association)
3813 -- and the parent of the actual argument (the call statement)
3818 if Nkind (P) = N_Parameter_Association then
3823 -- Only need to worry if we are argument of a procedure call
3824 -- since functions don't have out parameters. If this is an
3825 -- indirect or dispatching call, get signature from the
3828 if Nkind (P) = N_Procedure_Call_Statement then
3829 L := Parameter_Associations (P);
3831 if Is_Entity_Name (Name (P)) then
3832 E := Entity (Name (P));
3834 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
3835 E := Etype (Name (P));
3838 -- Only need to worry if there are indeed actuals, and if
3839 -- this could be a procedure call, otherwise we cannot get a
3840 -- match (either we are not an argument, or the mode of the
3841 -- formal is not OUT). This test also filters out the
3844 if Is_Non_Empty_List (L)
3845 and then Is_Subprogram (E)
3847 -- This is the loop through parameters, looking for an
3848 -- OUT parameter for which we are the argument.
3850 F := First_Formal (E);
3852 while Present (F) loop
3853 if Ekind (F) = E_Out_Parameter and then A = N then
3866 -- If we fall through, a validity check is required
3868 Insert_Valid_Check (Expr);
3871 ----------------------
3872 -- Expr_Known_Valid --
3873 ----------------------
3875 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
3876 Typ : constant Entity_Id := Etype (Expr);
3879 -- Non-scalar types are always considered valid, since they never give
3880 -- rise to the issues of erroneous or bounded error behavior that are
3881 -- the concern. In formal reference manual terms the notion of validity
3882 -- only applies to scalar types. Note that even when packed arrays are
3883 -- represented using modular types, they are still arrays semantically,
3884 -- so they are also always valid (in particular, the unused bits can be
3885 -- random rubbish without affecting the validity of the array value).
3887 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
3890 -- If no validity checking, then everything is considered valid
3892 elsif not Validity_Checks_On then
3895 -- Floating-point types are considered valid unless floating-point
3896 -- validity checks have been specifically turned on.
3898 elsif Is_Floating_Point_Type (Typ)
3899 and then not Validity_Check_Floating_Point
3903 -- If the expression is the value of an object that is known to be
3904 -- valid, then clearly the expression value itself is valid.
3906 elsif Is_Entity_Name (Expr)
3907 and then Is_Known_Valid (Entity (Expr))
3911 -- References to discriminants are always considered valid. The value
3912 -- of a discriminant gets checked when the object is built. Within the
3913 -- record, we consider it valid, and it is important to do so, since
3914 -- otherwise we can try to generate bogus validity checks which
3915 -- reference discriminants out of scope. Discriminants of concurrent
3916 -- types are excluded for the same reason.
3918 elsif Is_Entity_Name (Expr)
3919 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
3923 -- If the type is one for which all values are known valid, then we are
3924 -- sure that the value is valid except in the slightly odd case where
3925 -- the expression is a reference to a variable whose size has been
3926 -- explicitly set to a value greater than the object size.
3928 elsif Is_Known_Valid (Typ) then
3929 if Is_Entity_Name (Expr)
3930 and then Ekind (Entity (Expr)) = E_Variable
3931 and then Esize (Entity (Expr)) > Esize (Typ)
3938 -- Integer and character literals always have valid values, where
3939 -- appropriate these will be range checked in any case.
3941 elsif Nkind (Expr) = N_Integer_Literal
3943 Nkind (Expr) = N_Character_Literal
3947 -- If we have a type conversion or a qualification of a known valid
3948 -- value, then the result will always be valid.
3950 elsif Nkind (Expr) = N_Type_Conversion
3952 Nkind (Expr) = N_Qualified_Expression
3954 return Expr_Known_Valid (Expression (Expr));
3956 -- The result of any operator is always considered valid, since we
3957 -- assume the necessary checks are done by the operator. For operators
3958 -- on floating-point operations, we must also check when the operation
3959 -- is the right-hand side of an assignment, or is an actual in a call.
3961 elsif Nkind (Expr) in N_Op then
3962 if Is_Floating_Point_Type (Typ)
3963 and then Validity_Check_Floating_Point
3965 (Nkind (Parent (Expr)) = N_Assignment_Statement
3966 or else Nkind (Parent (Expr)) = N_Function_Call
3967 or else Nkind (Parent (Expr)) = N_Parameter_Association)
3974 -- The result of a membership test is always valid, since it is true or
3975 -- false, there are no other possibilities.
3977 elsif Nkind (Expr) in N_Membership_Test then
3980 -- For all other cases, we do not know the expression is valid
3985 end Expr_Known_Valid;
3991 procedure Find_Check
3993 Check_Type : Character;
3994 Target_Type : Entity_Id;
3995 Entry_OK : out Boolean;
3996 Check_Num : out Nat;
3997 Ent : out Entity_Id;
4000 function Within_Range_Of
4001 (Target_Type : Entity_Id;
4002 Check_Type : Entity_Id) return Boolean;
4003 -- Given a requirement for checking a range against Target_Type, and
4004 -- and a range Check_Type against which a check has already been made,
4005 -- determines if the check against check type is sufficient to ensure
4006 -- that no check against Target_Type is required.
4008 ---------------------
4009 -- Within_Range_Of --
4010 ---------------------
4012 function Within_Range_Of
4013 (Target_Type : Entity_Id;
4014 Check_Type : Entity_Id) return Boolean
4017 if Target_Type = Check_Type then
4022 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
4023 Thi : constant Node_Id := Type_High_Bound (Target_Type);
4024 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
4025 Chi : constant Node_Id := Type_High_Bound (Check_Type);
4029 or else (Compile_Time_Known_Value (Tlo)
4031 Compile_Time_Known_Value (Clo)
4033 Expr_Value (Clo) >= Expr_Value (Tlo)))
4036 or else (Compile_Time_Known_Value (Thi)
4038 Compile_Time_Known_Value (Chi)
4040 Expr_Value (Chi) <= Expr_Value (Clo)))
4048 end Within_Range_Of;
4050 -- Start of processing for Find_Check
4053 -- Establish default, to avoid warnings from GCC
4057 -- Case of expression is simple entity reference
4059 if Is_Entity_Name (Expr) then
4060 Ent := Entity (Expr);
4063 -- Case of expression is entity + known constant
4065 elsif Nkind (Expr) = N_Op_Add
4066 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4067 and then Is_Entity_Name (Left_Opnd (Expr))
4069 Ent := Entity (Left_Opnd (Expr));
4070 Ofs := Expr_Value (Right_Opnd (Expr));
4072 -- Case of expression is entity - known constant
4074 elsif Nkind (Expr) = N_Op_Subtract
4075 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4076 and then Is_Entity_Name (Left_Opnd (Expr))
4078 Ent := Entity (Left_Opnd (Expr));
4079 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
4081 -- Any other expression is not of the right form
4090 -- Come here with expression of appropriate form, check if entity is an
4091 -- appropriate one for our purposes.
4093 if (Ekind (Ent) = E_Variable
4095 Ekind (Ent) = E_Constant
4097 Ekind (Ent) = E_Loop_Parameter
4099 Ekind (Ent) = E_In_Parameter)
4100 and then not Is_Library_Level_Entity (Ent)
4108 -- See if there is matching check already
4110 for J in reverse 1 .. Num_Saved_Checks loop
4112 SC : Saved_Check renames Saved_Checks (J);
4115 if SC.Killed = False
4116 and then SC.Entity = Ent
4117 and then SC.Offset = Ofs
4118 and then SC.Check_Type = Check_Type
4119 and then Within_Range_Of (Target_Type, SC.Target_Type)
4127 -- If we fall through entry was not found
4133 ---------------------------------
4134 -- Generate_Discriminant_Check --
4135 ---------------------------------
4137 -- Note: the code for this procedure is derived from the
4138 -- Emit_Discriminant_Check Routine in trans.c.
4140 procedure Generate_Discriminant_Check (N : Node_Id) is
4141 Loc : constant Source_Ptr := Sloc (N);
4142 Pref : constant Node_Id := Prefix (N);
4143 Sel : constant Node_Id := Selector_Name (N);
4145 Orig_Comp : constant Entity_Id :=
4146 Original_Record_Component (Entity (Sel));
4147 -- The original component to be checked
4149 Discr_Fct : constant Entity_Id :=
4150 Discriminant_Checking_Func (Orig_Comp);
4151 -- The discriminant checking function
4154 -- One discriminant to be checked in the type
4156 Real_Discr : Entity_Id;
4157 -- Actual discriminant in the call
4159 Pref_Type : Entity_Id;
4160 -- Type of relevant prefix (ignoring private/access stuff)
4163 -- List of arguments for function call
4166 -- Keep track of the formal corresponding to the actual we build for
4167 -- each discriminant, in order to be able to perform the necessary type
4171 -- Selected component reference for checking function argument
4174 Pref_Type := Etype (Pref);
4176 -- Force evaluation of the prefix, so that it does not get evaluated
4177 -- twice (once for the check, once for the actual reference). Such a
4178 -- double evaluation is always a potential source of inefficiency,
4179 -- and is functionally incorrect in the volatile case, or when the
4180 -- prefix may have side-effects. An entity or a component of an
4181 -- entity requires no evaluation.
4183 if Is_Entity_Name (Pref) then
4184 if Treat_As_Volatile (Entity (Pref)) then
4185 Force_Evaluation (Pref, Name_Req => True);
4188 elsif Treat_As_Volatile (Etype (Pref)) then
4189 Force_Evaluation (Pref, Name_Req => True);
4191 elsif Nkind (Pref) = N_Selected_Component
4192 and then Is_Entity_Name (Prefix (Pref))
4197 Force_Evaluation (Pref, Name_Req => True);
4200 -- For a tagged type, use the scope of the original component to
4201 -- obtain the type, because ???
4203 if Is_Tagged_Type (Scope (Orig_Comp)) then
4204 Pref_Type := Scope (Orig_Comp);
4206 -- For an untagged derived type, use the discriminants of the parent
4207 -- which have been renamed in the derivation, possibly by a one-to-many
4208 -- discriminant constraint. For non-tagged type, initially get the Etype
4212 if Is_Derived_Type (Pref_Type)
4213 and then Number_Discriminants (Pref_Type) /=
4214 Number_Discriminants (Etype (Base_Type (Pref_Type)))
4216 Pref_Type := Etype (Base_Type (Pref_Type));
4220 -- We definitely should have a checking function, This routine should
4221 -- not be called if no discriminant checking function is present.
4223 pragma Assert (Present (Discr_Fct));
4225 -- Create the list of the actual parameters for the call. This list
4226 -- is the list of the discriminant fields of the record expression to
4227 -- be discriminant checked.
4230 Formal := First_Formal (Discr_Fct);
4231 Discr := First_Discriminant (Pref_Type);
4232 while Present (Discr) loop
4234 -- If we have a corresponding discriminant field, and a parent
4235 -- subtype is present, then we want to use the corresponding
4236 -- discriminant since this is the one with the useful value.
4238 if Present (Corresponding_Discriminant (Discr))
4239 and then Ekind (Pref_Type) = E_Record_Type
4240 and then Present (Parent_Subtype (Pref_Type))
4242 Real_Discr := Corresponding_Discriminant (Discr);
4244 Real_Discr := Discr;
4247 -- Construct the reference to the discriminant
4250 Make_Selected_Component (Loc,
4252 Unchecked_Convert_To (Pref_Type,
4253 Duplicate_Subexpr (Pref)),
4254 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
4256 -- Manually analyze and resolve this selected component. We really
4257 -- want it just as it appears above, and do not want the expander
4258 -- playing discriminal games etc with this reference. Then we append
4259 -- the argument to the list we are gathering.
4261 Set_Etype (Scomp, Etype (Real_Discr));
4262 Set_Analyzed (Scomp, True);
4263 Append_To (Args, Convert_To (Etype (Formal), Scomp));
4265 Next_Formal_With_Extras (Formal);
4266 Next_Discriminant (Discr);
4269 -- Now build and insert the call
4272 Make_Raise_Constraint_Error (Loc,
4274 Make_Function_Call (Loc,
4275 Name => New_Occurrence_Of (Discr_Fct, Loc),
4276 Parameter_Associations => Args),
4277 Reason => CE_Discriminant_Check_Failed));
4278 end Generate_Discriminant_Check;
4280 ---------------------------
4281 -- Generate_Index_Checks --
4282 ---------------------------
4284 procedure Generate_Index_Checks (N : Node_Id) is
4285 Loc : constant Source_Ptr := Sloc (N);
4286 A : constant Node_Id := Prefix (N);
4292 -- Ignore call if index checks suppressed for array object or type
4294 if (Is_Entity_Name (A) and then Index_Checks_Suppressed (Entity (A)))
4295 or else Index_Checks_Suppressed (Etype (A))
4300 -- Generate the checks
4302 Sub := First (Expressions (N));
4304 while Present (Sub) loop
4305 if Do_Range_Check (Sub) then
4306 Set_Do_Range_Check (Sub, False);
4308 -- Force evaluation except for the case of a simple name of a
4309 -- non-volatile entity.
4311 if not Is_Entity_Name (Sub)
4312 or else Treat_As_Volatile (Entity (Sub))
4314 Force_Evaluation (Sub);
4317 -- Generate a raise of constraint error with the appropriate
4318 -- reason and a condition of the form:
4320 -- Base_Type(Sub) not in array'range (subscript)
4322 -- Note that the reason we generate the conversion to the base
4323 -- type here is that we definitely want the range check to take
4324 -- place, even if it looks like the subtype is OK. Optimization
4325 -- considerations that allow us to omit the check have already
4326 -- been taken into account in the setting of the Do_Range_Check
4332 Num := New_List (Make_Integer_Literal (Loc, Ind));
4336 Make_Raise_Constraint_Error (Loc,
4340 Convert_To (Base_Type (Etype (Sub)),
4341 Duplicate_Subexpr_Move_Checks (Sub)),
4343 Make_Attribute_Reference (Loc,
4344 Prefix => Duplicate_Subexpr_Move_Checks (A),
4345 Attribute_Name => Name_Range,
4346 Expressions => Num)),
4347 Reason => CE_Index_Check_Failed));
4353 end Generate_Index_Checks;
4355 --------------------------
4356 -- Generate_Range_Check --
4357 --------------------------
4359 procedure Generate_Range_Check
4361 Target_Type : Entity_Id;
4362 Reason : RT_Exception_Code)
4364 Loc : constant Source_Ptr := Sloc (N);
4365 Source_Type : constant Entity_Id := Etype (N);
4366 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
4367 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
4370 -- First special case, if the source type is already within the range
4371 -- of the target type, then no check is needed (probably we should have
4372 -- stopped Do_Range_Check from being set in the first place, but better
4373 -- late than later in preventing junk code!
4375 -- We do NOT apply this if the source node is a literal, since in this
4376 -- case the literal has already been labeled as having the subtype of
4379 if In_Subrange_Of (Source_Type, Target_Type)
4381 (Nkind (N) = N_Integer_Literal
4383 Nkind (N) = N_Real_Literal
4385 Nkind (N) = N_Character_Literal
4388 and then Ekind (Entity (N)) = E_Enumeration_Literal))
4393 -- We need a check, so force evaluation of the node, so that it does
4394 -- not get evaluated twice (once for the check, once for the actual
4395 -- reference). Such a double evaluation is always a potential source
4396 -- of inefficiency, and is functionally incorrect in the volatile case.
4398 if not Is_Entity_Name (N)
4399 or else Treat_As_Volatile (Entity (N))
4401 Force_Evaluation (N);
4404 -- The easiest case is when Source_Base_Type and Target_Base_Type are
4405 -- the same since in this case we can simply do a direct check of the
4406 -- value of N against the bounds of Target_Type.
4408 -- [constraint_error when N not in Target_Type]
4410 -- Note: this is by far the most common case, for example all cases of
4411 -- checks on the RHS of assignments are in this category, but not all
4412 -- cases are like this. Notably conversions can involve two types.
4414 if Source_Base_Type = Target_Base_Type then
4416 Make_Raise_Constraint_Error (Loc,
4419 Left_Opnd => Duplicate_Subexpr (N),
4420 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4423 -- Next test for the case where the target type is within the bounds
4424 -- of the base type of the source type, since in this case we can
4425 -- simply convert these bounds to the base type of T to do the test.
4427 -- [constraint_error when N not in
4428 -- Source_Base_Type (Target_Type'First)
4430 -- Source_Base_Type(Target_Type'Last))]
4432 -- The conversions will always work and need no check
4434 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
4436 Make_Raise_Constraint_Error (Loc,
4439 Left_Opnd => Duplicate_Subexpr (N),
4444 Convert_To (Source_Base_Type,
4445 Make_Attribute_Reference (Loc,
4447 New_Occurrence_Of (Target_Type, Loc),
4448 Attribute_Name => Name_First)),
4451 Convert_To (Source_Base_Type,
4452 Make_Attribute_Reference (Loc,
4454 New_Occurrence_Of (Target_Type, Loc),
4455 Attribute_Name => Name_Last)))),
4458 -- Note that at this stage we now that the Target_Base_Type is not in
4459 -- the range of the Source_Base_Type (since even the Target_Type itself
4460 -- is not in this range). It could still be the case that Source_Type is
4461 -- in range of the target base type since we have not checked that case.
4463 -- If that is the case, we can freely convert the source to the target,
4464 -- and then test the target result against the bounds.
4466 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
4468 -- We make a temporary to hold the value of the converted value
4469 -- (converted to the base type), and then we will do the test against
4472 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
4473 -- [constraint_error when Tnn not in Target_Type]
4475 -- Then the conversion itself is replaced by an occurrence of Tnn
4478 Tnn : constant Entity_Id :=
4479 Make_Defining_Identifier (Loc,
4480 Chars => New_Internal_Name ('T'));
4483 Insert_Actions (N, New_List (
4484 Make_Object_Declaration (Loc,
4485 Defining_Identifier => Tnn,
4486 Object_Definition =>
4487 New_Occurrence_Of (Target_Base_Type, Loc),
4488 Constant_Present => True,
4490 Make_Type_Conversion (Loc,
4491 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
4492 Expression => Duplicate_Subexpr (N))),
4494 Make_Raise_Constraint_Error (Loc,
4497 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4498 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4500 Reason => Reason)));
4502 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4504 -- Set the type of N, because the declaration for Tnn might not
4505 -- be analyzed yet, as is the case if N appears within a record
4506 -- declaration, as a discriminant constraint or expression.
4508 Set_Etype (N, Target_Base_Type);
4511 -- At this stage, we know that we have two scalar types, which are
4512 -- directly convertible, and where neither scalar type has a base
4513 -- range that is in the range of the other scalar type.
4515 -- The only way this can happen is with a signed and unsigned type.
4516 -- So test for these two cases:
4519 -- Case of the source is unsigned and the target is signed
4521 if Is_Unsigned_Type (Source_Base_Type)
4522 and then not Is_Unsigned_Type (Target_Base_Type)
4524 -- If the source is unsigned and the target is signed, then we
4525 -- know that the source is not shorter than the target (otherwise
4526 -- the source base type would be in the target base type range).
4528 -- In other words, the unsigned type is either the same size as
4529 -- the target, or it is larger. It cannot be smaller.
4532 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
4534 -- We only need to check the low bound if the low bound of the
4535 -- target type is non-negative. If the low bound of the target
4536 -- type is negative, then we know that we will fit fine.
4538 -- If the high bound of the target type is negative, then we
4539 -- know we have a constraint error, since we can't possibly
4540 -- have a negative source.
4542 -- With these two checks out of the way, we can do the check
4543 -- using the source type safely
4545 -- This is definitely the most annoying case!
4547 -- [constraint_error
4548 -- when (Target_Type'First >= 0
4550 -- N < Source_Base_Type (Target_Type'First))
4551 -- or else Target_Type'Last < 0
4552 -- or else N > Source_Base_Type (Target_Type'Last)];
4554 -- We turn off all checks since we know that the conversions
4555 -- will work fine, given the guards for negative values.
4558 Make_Raise_Constraint_Error (Loc,
4564 Left_Opnd => Make_Op_Ge (Loc,
4566 Make_Attribute_Reference (Loc,
4568 New_Occurrence_Of (Target_Type, Loc),
4569 Attribute_Name => Name_First),
4570 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4574 Left_Opnd => Duplicate_Subexpr (N),
4576 Convert_To (Source_Base_Type,
4577 Make_Attribute_Reference (Loc,
4579 New_Occurrence_Of (Target_Type, Loc),
4580 Attribute_Name => Name_First)))),
4585 Make_Attribute_Reference (Loc,
4586 Prefix => New_Occurrence_Of (Target_Type, Loc),
4587 Attribute_Name => Name_Last),
4588 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
4592 Left_Opnd => Duplicate_Subexpr (N),
4594 Convert_To (Source_Base_Type,
4595 Make_Attribute_Reference (Loc,
4596 Prefix => New_Occurrence_Of (Target_Type, Loc),
4597 Attribute_Name => Name_Last)))),
4600 Suppress => All_Checks);
4602 -- Only remaining possibility is that the source is signed and
4603 -- the target is unsigned
4606 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
4607 and then Is_Unsigned_Type (Target_Base_Type));
4609 -- If the source is signed and the target is unsigned, then we
4610 -- know that the target is not shorter than the source (otherwise
4611 -- the target base type would be in the source base type range).
4613 -- In other words, the unsigned type is either the same size as
4614 -- the target, or it is larger. It cannot be smaller.
4616 -- Clearly we have an error if the source value is negative since
4617 -- no unsigned type can have negative values. If the source type
4618 -- is non-negative, then the check can be done using the target
4621 -- Tnn : constant Target_Base_Type (N) := Target_Type;
4623 -- [constraint_error
4624 -- when N < 0 or else Tnn not in Target_Type];
4626 -- We turn off all checks for the conversion of N to the target
4627 -- base type, since we generate the explicit check to ensure that
4628 -- the value is non-negative
4631 Tnn : constant Entity_Id :=
4632 Make_Defining_Identifier (Loc,
4633 Chars => New_Internal_Name ('T'));
4636 Insert_Actions (N, New_List (
4637 Make_Object_Declaration (Loc,
4638 Defining_Identifier => Tnn,
4639 Object_Definition =>
4640 New_Occurrence_Of (Target_Base_Type, Loc),
4641 Constant_Present => True,
4643 Make_Type_Conversion (Loc,
4645 New_Occurrence_Of (Target_Base_Type, Loc),
4646 Expression => Duplicate_Subexpr (N))),
4648 Make_Raise_Constraint_Error (Loc,
4653 Left_Opnd => Duplicate_Subexpr (N),
4654 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4658 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4660 New_Occurrence_Of (Target_Type, Loc))),
4663 Suppress => All_Checks);
4665 -- Set the Etype explicitly, because Insert_Actions may have
4666 -- placed the declaration in the freeze list for an enclosing
4667 -- construct, and thus it is not analyzed yet.
4669 Set_Etype (Tnn, Target_Base_Type);
4670 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4674 end Generate_Range_Check;
4680 function Get_Check_Id (N : Name_Id) return Check_Id is
4682 -- For standard check name, we can do a direct computation
4684 if N in First_Check_Name .. Last_Check_Name then
4685 return Check_Id (N - (First_Check_Name - 1));
4687 -- For non-standard names added by pragma Check_Name, search table
4690 for J in All_Checks + 1 .. Check_Names.Last loop
4691 if Check_Names.Table (J) = N then
4697 -- No matching name found
4702 ---------------------
4703 -- Get_Discriminal --
4704 ---------------------
4706 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
4707 Loc : constant Source_Ptr := Sloc (E);
4712 -- The bound can be a bona fide parameter of a protected operation,
4713 -- rather than a prival encoded as an in-parameter.
4715 if No (Discriminal_Link (Entity (Bound))) then
4719 -- Climb the scope stack looking for an enclosing protected type. If
4720 -- we run out of scopes, return the bound itself.
4723 while Present (Sc) loop
4724 if Sc = Standard_Standard then
4727 elsif Ekind (Sc) = E_Protected_Type then
4734 D := First_Discriminant (Sc);
4735 while Present (D) loop
4736 if Chars (D) = Chars (Bound) then
4737 return New_Occurrence_Of (Discriminal (D), Loc);
4740 Next_Discriminant (D);
4744 end Get_Discriminal;
4746 ----------------------
4747 -- Get_Range_Checks --
4748 ----------------------
4750 function Get_Range_Checks
4752 Target_Typ : Entity_Id;
4753 Source_Typ : Entity_Id := Empty;
4754 Warn_Node : Node_Id := Empty) return Check_Result
4757 return Selected_Range_Checks
4758 (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
4759 end Get_Range_Checks;
4765 function Guard_Access
4768 Ck_Node : Node_Id) return Node_Id
4771 if Nkind (Cond) = N_Or_Else then
4772 Set_Paren_Count (Cond, 1);
4775 if Nkind (Ck_Node) = N_Allocator then
4782 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
4783 Right_Opnd => Make_Null (Loc)),
4784 Right_Opnd => Cond);
4788 -----------------------------
4789 -- Index_Checks_Suppressed --
4790 -----------------------------
4792 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
4794 if Present (E) and then Checks_May_Be_Suppressed (E) then
4795 return Is_Check_Suppressed (E, Index_Check);
4797 return Scope_Suppress (Index_Check);
4799 end Index_Checks_Suppressed;
4805 procedure Initialize is
4807 for J in Determine_Range_Cache_N'Range loop
4808 Determine_Range_Cache_N (J) := Empty;
4813 for J in Int range 1 .. All_Checks loop
4814 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
4818 -------------------------
4819 -- Insert_Range_Checks --
4820 -------------------------
4822 procedure Insert_Range_Checks
4823 (Checks : Check_Result;
4825 Suppress_Typ : Entity_Id;
4826 Static_Sloc : Source_Ptr := No_Location;
4827 Flag_Node : Node_Id := Empty;
4828 Do_Before : Boolean := False)
4830 Internal_Flag_Node : Node_Id := Flag_Node;
4831 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
4833 Check_Node : Node_Id;
4834 Checks_On : constant Boolean :=
4835 (not Index_Checks_Suppressed (Suppress_Typ))
4837 (not Range_Checks_Suppressed (Suppress_Typ));
4840 -- For now we just return if Checks_On is false, however this should be
4841 -- enhanced to check for an always True value in the condition and to
4842 -- generate a compilation warning???
4844 if not Expander_Active or else not Checks_On then
4848 if Static_Sloc = No_Location then
4849 Internal_Static_Sloc := Sloc (Node);
4852 if No (Flag_Node) then
4853 Internal_Flag_Node := Node;
4856 for J in 1 .. 2 loop
4857 exit when No (Checks (J));
4859 if Nkind (Checks (J)) = N_Raise_Constraint_Error
4860 and then Present (Condition (Checks (J)))
4862 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
4863 Check_Node := Checks (J);
4864 Mark_Rewrite_Insertion (Check_Node);
4867 Insert_Before_And_Analyze (Node, Check_Node);
4869 Insert_After_And_Analyze (Node, Check_Node);
4872 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
4877 Make_Raise_Constraint_Error (Internal_Static_Sloc,
4878 Reason => CE_Range_Check_Failed);
4879 Mark_Rewrite_Insertion (Check_Node);
4882 Insert_Before_And_Analyze (Node, Check_Node);
4884 Insert_After_And_Analyze (Node, Check_Node);
4888 end Insert_Range_Checks;
4890 ------------------------
4891 -- Insert_Valid_Check --
4892 ------------------------
4894 procedure Insert_Valid_Check (Expr : Node_Id) is
4895 Loc : constant Source_Ptr := Sloc (Expr);
4899 -- Do not insert if checks off, or if not checking validity
4901 if not Validity_Checks_On
4902 or else Range_Or_Validity_Checks_Suppressed (Expr)
4907 -- If we have a checked conversion, then validity check applies to
4908 -- the expression inside the conversion, not the result, since if
4909 -- the expression inside is valid, then so is the conversion result.
4912 while Nkind (Exp) = N_Type_Conversion loop
4913 Exp := Expression (Exp);
4916 -- We are about to insert the validity check for Exp. We save and
4917 -- reset the Do_Range_Check flag over this validity check, and then
4918 -- put it back for the final original reference (Exp may be rewritten).
4921 DRC : constant Boolean := Do_Range_Check (Exp);
4924 Set_Do_Range_Check (Exp, False);
4926 -- Insert the validity check. Note that we do this with validity
4927 -- checks turned off, to avoid recursion, we do not want validity
4928 -- checks on the validity checking code itself!
4932 Make_Raise_Constraint_Error (Loc,
4936 Make_Attribute_Reference (Loc,
4938 Duplicate_Subexpr_No_Checks (Exp, Name_Req => True),
4939 Attribute_Name => Name_Valid)),
4940 Reason => CE_Invalid_Data),
4941 Suppress => Validity_Check);
4943 -- If the expression is a a reference to an element of a bit-packed
4944 -- array, then it is rewritten as a renaming declaration. If the
4945 -- expression is an actual in a call, it has not been expanded,
4946 -- waiting for the proper point at which to do it. The same happens
4947 -- with renamings, so that we have to force the expansion now. This
4948 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
4951 if Is_Entity_Name (Exp)
4952 and then Nkind (Parent (Entity (Exp))) =
4953 N_Object_Renaming_Declaration
4956 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
4958 if Nkind (Old_Exp) = N_Indexed_Component
4959 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
4961 Expand_Packed_Element_Reference (Old_Exp);
4966 -- Put back the Do_Range_Check flag on the resulting (possibly
4967 -- rewritten) expression.
4969 -- Note: it might be thought that a validity check is not required
4970 -- when a range check is present, but that's not the case, because
4971 -- the back end is allowed to assume for the range check that the
4972 -- operand is within its declared range (an assumption that validity
4973 -- checking is all about NOT assuming!)
4975 -- Note: no need to worry about Possible_Local_Raise here, it will
4976 -- already have been called if original node has Do_Range_Check set.
4978 Set_Do_Range_Check (Exp, DRC);
4980 end Insert_Valid_Check;
4982 ----------------------------------
4983 -- Install_Null_Excluding_Check --
4984 ----------------------------------
4986 procedure Install_Null_Excluding_Check (N : Node_Id) is
4987 Loc : constant Source_Ptr := Sloc (N);
4988 Typ : constant Entity_Id := Etype (N);
4990 function In_Declarative_Region_Of_Subprogram_Body return Boolean;
4991 -- Determine whether node N, a reference to an *in* parameter, is
4992 -- inside the declarative region of the current subprogram body.
4994 procedure Mark_Non_Null;
4995 -- After installation of check, if the node in question is an entity
4996 -- name, then mark this entity as non-null if possible.
4998 ----------------------------------------------
4999 -- In_Declarative_Region_Of_Subprogram_Body --
5000 ----------------------------------------------
5002 function In_Declarative_Region_Of_Subprogram_Body return Boolean is
5003 E : constant Entity_Id := Entity (N);
5004 S : constant Entity_Id := Current_Scope;
5008 pragma Assert (Ekind (E) = E_In_Parameter);
5010 -- Two initial context checks. We must be inside a subprogram body
5011 -- with declarations and reference must not appear in nested scopes.
5013 if (Ekind (S) /= E_Function
5014 and then Ekind (S) /= E_Procedure)
5015 or else Scope (E) /= S
5020 S_Par := Parent (Parent (S));
5022 if Nkind (S_Par) /= N_Subprogram_Body
5023 or else No (Declarations (S_Par))
5033 -- Retrieve the declaration node of N (if any). Note that N
5034 -- may be a part of a complex initialization expression.
5038 while Present (P) loop
5040 -- While traversing the parent chain, we find that N
5041 -- belongs to a statement, thus it may never appear in
5042 -- a declarative region.
5044 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
5045 or else Nkind (P) = N_Procedure_Call_Statement
5050 if Nkind (P) in N_Declaration
5051 and then Nkind (P) not in N_Subprogram_Specification
5064 return List_Containing (N_Decl) = Declarations (S_Par);
5066 end In_Declarative_Region_Of_Subprogram_Body;
5072 procedure Mark_Non_Null is
5074 -- Only case of interest is if node N is an entity name
5076 if Is_Entity_Name (N) then
5078 -- For sure, we want to clear an indication that this is known to
5079 -- be null, since if we get past this check, it definitely is not!
5081 Set_Is_Known_Null (Entity (N), False);
5083 -- We can mark the entity as known to be non-null if either it is
5084 -- safe to capture the value, or in the case of an IN parameter,
5085 -- which is a constant, if the check we just installed is in the
5086 -- declarative region of the subprogram body. In this latter case,
5087 -- a check is decisive for the rest of the body, since we know we
5088 -- must complete all declarations before executing the body.
5090 if Safe_To_Capture_Value (N, Entity (N))
5092 (Ekind (Entity (N)) = E_In_Parameter
5093 and then In_Declarative_Region_Of_Subprogram_Body)
5095 Set_Is_Known_Non_Null (Entity (N));
5100 -- Start of processing for Install_Null_Excluding_Check
5103 pragma Assert (Is_Access_Type (Typ));
5105 -- No check inside a generic (why not???)
5107 if Inside_A_Generic then
5111 -- No check needed if known to be non-null
5113 if Known_Non_Null (N) then
5117 -- If known to be null, here is where we generate a compile time check
5119 if Known_Null (N) then
5120 Apply_Compile_Time_Constraint_Error
5122 "null value not allowed here?",
5123 CE_Access_Check_Failed);
5128 -- If entity is never assigned, for sure a warning is appropriate
5130 if Is_Entity_Name (N) then
5131 Check_Unset_Reference (N);
5134 -- No check needed if checks are suppressed on the range. Note that we
5135 -- don't set Is_Known_Non_Null in this case (we could legitimately do
5136 -- so, since the program is erroneous, but we don't like to casually
5137 -- propagate such conclusions from erroneosity).
5139 if Access_Checks_Suppressed (Typ) then
5143 -- No check needed for access to concurrent record types generated by
5144 -- the expander. This is not just an optimization (though it does indeed
5145 -- remove junk checks). It also avoids generation of junk warnings.
5147 if Nkind (N) in N_Has_Chars
5148 and then Chars (N) = Name_uObject
5149 and then Is_Concurrent_Record_Type
5150 (Directly_Designated_Type (Etype (N)))
5155 -- Otherwise install access check
5158 Make_Raise_Constraint_Error (Loc,
5161 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
5162 Right_Opnd => Make_Null (Loc)),
5163 Reason => CE_Access_Check_Failed));
5166 end Install_Null_Excluding_Check;
5168 --------------------------
5169 -- Install_Static_Check --
5170 --------------------------
5172 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
5173 Stat : constant Boolean := Is_Static_Expression (R_Cno);
5174 Typ : constant Entity_Id := Etype (R_Cno);
5178 Make_Raise_Constraint_Error (Loc,
5179 Reason => CE_Range_Check_Failed));
5180 Set_Analyzed (R_Cno);
5181 Set_Etype (R_Cno, Typ);
5182 Set_Raises_Constraint_Error (R_Cno);
5183 Set_Is_Static_Expression (R_Cno, Stat);
5184 end Install_Static_Check;
5186 ---------------------
5187 -- Kill_All_Checks --
5188 ---------------------
5190 procedure Kill_All_Checks is
5192 if Debug_Flag_CC then
5193 w ("Kill_All_Checks");
5196 -- We reset the number of saved checks to zero, and also modify all
5197 -- stack entries for statement ranges to indicate that the number of
5198 -- checks at each level is now zero.
5200 Num_Saved_Checks := 0;
5202 for J in 1 .. Saved_Checks_TOS loop
5203 Saved_Checks_Stack (J) := 0;
5205 end Kill_All_Checks;
5211 procedure Kill_Checks (V : Entity_Id) is
5213 if Debug_Flag_CC then
5214 w ("Kill_Checks for entity", Int (V));
5217 for J in 1 .. Num_Saved_Checks loop
5218 if Saved_Checks (J).Entity = V then
5219 if Debug_Flag_CC then
5220 w (" Checks killed for saved check ", J);
5223 Saved_Checks (J).Killed := True;
5228 ------------------------------
5229 -- Length_Checks_Suppressed --
5230 ------------------------------
5232 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
5234 if Present (E) and then Checks_May_Be_Suppressed (E) then
5235 return Is_Check_Suppressed (E, Length_Check);
5237 return Scope_Suppress (Length_Check);
5239 end Length_Checks_Suppressed;
5241 --------------------------------
5242 -- Overflow_Checks_Suppressed --
5243 --------------------------------
5245 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
5247 if Present (E) and then Checks_May_Be_Suppressed (E) then
5248 return Is_Check_Suppressed (E, Overflow_Check);
5250 return Scope_Suppress (Overflow_Check);
5252 end Overflow_Checks_Suppressed;
5253 -----------------------------
5254 -- Range_Checks_Suppressed --
5255 -----------------------------
5257 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
5261 -- Note: for now we always suppress range checks on Vax float types,
5262 -- since Gigi does not know how to generate these checks.
5264 if Vax_Float (E) then
5266 elsif Kill_Range_Checks (E) then
5268 elsif Checks_May_Be_Suppressed (E) then
5269 return Is_Check_Suppressed (E, Range_Check);
5273 return Scope_Suppress (Range_Check);
5274 end Range_Checks_Suppressed;
5276 -----------------------------------------
5277 -- Range_Or_Validity_Checks_Suppressed --
5278 -----------------------------------------
5280 -- Note: the coding would be simpler here if we simply made appropriate
5281 -- calls to Range/Validity_Checks_Suppressed, but that would result in
5282 -- duplicated checks which we prefer to avoid.
5284 function Range_Or_Validity_Checks_Suppressed
5285 (Expr : Node_Id) return Boolean
5288 -- Immediate return if scope checks suppressed for either check
5290 if Scope_Suppress (Range_Check) or Scope_Suppress (Validity_Check) then
5294 -- If no expression, that's odd, decide that checks are suppressed,
5295 -- since we don't want anyone trying to do checks in this case, which
5296 -- is most likely the result of some other error.
5302 -- Expression is present, so perform suppress checks on type
5305 Typ : constant Entity_Id := Etype (Expr);
5307 if Vax_Float (Typ) then
5309 elsif Checks_May_Be_Suppressed (Typ)
5310 and then (Is_Check_Suppressed (Typ, Range_Check)
5312 Is_Check_Suppressed (Typ, Validity_Check))
5318 -- If expression is an entity name, perform checks on this entity
5320 if Is_Entity_Name (Expr) then
5322 Ent : constant Entity_Id := Entity (Expr);
5324 if Checks_May_Be_Suppressed (Ent) then
5325 return Is_Check_Suppressed (Ent, Range_Check)
5326 or else Is_Check_Suppressed (Ent, Validity_Check);
5331 -- If we fall through, no checks suppressed
5334 end Range_Or_Validity_Checks_Suppressed;
5340 procedure Remove_Checks (Expr : Node_Id) is
5341 Discard : Traverse_Result;
5342 pragma Warnings (Off, Discard);
5344 function Process (N : Node_Id) return Traverse_Result;
5345 -- Process a single node during the traversal
5347 function Traverse is new Traverse_Func (Process);
5348 -- The traversal function itself
5354 function Process (N : Node_Id) return Traverse_Result is
5356 if Nkind (N) not in N_Subexpr then
5360 Set_Do_Range_Check (N, False);
5364 Discard := Traverse (Left_Opnd (N));
5367 when N_Attribute_Reference =>
5368 Set_Do_Overflow_Check (N, False);
5370 when N_Function_Call =>
5371 Set_Do_Tag_Check (N, False);
5374 Set_Do_Overflow_Check (N, False);
5378 Set_Do_Division_Check (N, False);
5381 Set_Do_Length_Check (N, False);
5384 Set_Do_Division_Check (N, False);
5387 Set_Do_Length_Check (N, False);
5390 Set_Do_Division_Check (N, False);
5393 Set_Do_Length_Check (N, False);
5400 Discard := Traverse (Left_Opnd (N));
5403 when N_Selected_Component =>
5404 Set_Do_Discriminant_Check (N, False);
5406 when N_Type_Conversion =>
5407 Set_Do_Length_Check (N, False);
5408 Set_Do_Tag_Check (N, False);
5409 Set_Do_Overflow_Check (N, False);
5418 -- Start of processing for Remove_Checks
5421 Discard := Traverse (Expr);
5424 ----------------------------
5425 -- Selected_Length_Checks --
5426 ----------------------------
5428 function Selected_Length_Checks
5430 Target_Typ : Entity_Id;
5431 Source_Typ : Entity_Id;
5432 Warn_Node : Node_Id) return Check_Result
5434 Loc : constant Source_Ptr := Sloc (Ck_Node);
5437 Expr_Actual : Node_Id;
5439 Cond : Node_Id := Empty;
5440 Do_Access : Boolean := False;
5441 Wnode : Node_Id := Warn_Node;
5442 Ret_Result : Check_Result := (Empty, Empty);
5443 Num_Checks : Natural := 0;
5445 procedure Add_Check (N : Node_Id);
5446 -- Adds the action given to Ret_Result if N is non-Empty
5448 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
5449 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
5450 -- Comments required ???
5452 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
5453 -- True for equal literals and for nodes that denote the same constant
5454 -- entity, even if its value is not a static constant. This includes the
5455 -- case of a discriminal reference within an init proc. Removes some
5456 -- obviously superfluous checks.
5458 function Length_E_Cond
5459 (Exptyp : Entity_Id;
5461 Indx : Nat) return Node_Id;
5462 -- Returns expression to compute:
5463 -- Typ'Length /= Exptyp'Length
5465 function Length_N_Cond
5468 Indx : Nat) return Node_Id;
5469 -- Returns expression to compute:
5470 -- Typ'Length /= Expr'Length
5476 procedure Add_Check (N : Node_Id) is
5480 -- For now, ignore attempt to place more than 2 checks ???
5482 if Num_Checks = 2 then
5486 pragma Assert (Num_Checks <= 1);
5487 Num_Checks := Num_Checks + 1;
5488 Ret_Result (Num_Checks) := N;
5496 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
5497 SE : constant Entity_Id := Scope (E);
5499 E1 : Entity_Id := E;
5502 if Ekind (Scope (E)) = E_Record_Type
5503 and then Has_Discriminants (Scope (E))
5505 N := Build_Discriminal_Subtype_Of_Component (E);
5508 Insert_Action (Ck_Node, N);
5509 E1 := Defining_Identifier (N);
5513 if Ekind (E1) = E_String_Literal_Subtype then
5515 Make_Integer_Literal (Loc,
5516 Intval => String_Literal_Length (E1));
5518 elsif SE /= Standard_Standard
5519 and then Ekind (Scope (SE)) = E_Protected_Type
5520 and then Has_Discriminants (Scope (SE))
5521 and then Has_Completion (Scope (SE))
5522 and then not Inside_Init_Proc
5524 -- If the type whose length is needed is a private component
5525 -- constrained by a discriminant, we must expand the 'Length
5526 -- attribute into an explicit computation, using the discriminal
5527 -- of the current protected operation. This is because the actual
5528 -- type of the prival is constructed after the protected opera-
5529 -- tion has been fully expanded.
5532 Indx_Type : Node_Id;
5535 Do_Expand : Boolean := False;
5538 Indx_Type := First_Index (E);
5540 for J in 1 .. Indx - 1 loop
5541 Next_Index (Indx_Type);
5544 Get_Index_Bounds (Indx_Type, Lo, Hi);
5546 if Nkind (Lo) = N_Identifier
5547 and then Ekind (Entity (Lo)) = E_In_Parameter
5549 Lo := Get_Discriminal (E, Lo);
5553 if Nkind (Hi) = N_Identifier
5554 and then Ekind (Entity (Hi)) = E_In_Parameter
5556 Hi := Get_Discriminal (E, Hi);
5561 if not Is_Entity_Name (Lo) then
5562 Lo := Duplicate_Subexpr_No_Checks (Lo);
5565 if not Is_Entity_Name (Hi) then
5566 Lo := Duplicate_Subexpr_No_Checks (Hi);
5572 Make_Op_Subtract (Loc,
5576 Right_Opnd => Make_Integer_Literal (Loc, 1));
5581 Make_Attribute_Reference (Loc,
5582 Attribute_Name => Name_Length,
5584 New_Occurrence_Of (E1, Loc));
5587 Set_Expressions (N, New_List (
5588 Make_Integer_Literal (Loc, Indx)));
5597 Make_Attribute_Reference (Loc,
5598 Attribute_Name => Name_Length,
5600 New_Occurrence_Of (E1, Loc));
5603 Set_Expressions (N, New_List (
5604 Make_Integer_Literal (Loc, Indx)));
5615 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
5618 Make_Attribute_Reference (Loc,
5619 Attribute_Name => Name_Length,
5621 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
5622 Expressions => New_List (
5623 Make_Integer_Literal (Loc, Indx)));
5630 function Length_E_Cond
5631 (Exptyp : Entity_Id;
5633 Indx : Nat) return Node_Id
5638 Left_Opnd => Get_E_Length (Typ, Indx),
5639 Right_Opnd => Get_E_Length (Exptyp, Indx));
5646 function Length_N_Cond
5649 Indx : Nat) return Node_Id
5654 Left_Opnd => Get_E_Length (Typ, Indx),
5655 Right_Opnd => Get_N_Length (Expr, Indx));
5662 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
5665 (Nkind (L) = N_Integer_Literal
5666 and then Nkind (R) = N_Integer_Literal
5667 and then Intval (L) = Intval (R))
5671 and then Ekind (Entity (L)) = E_Constant
5672 and then ((Is_Entity_Name (R)
5673 and then Entity (L) = Entity (R))
5675 (Nkind (R) = N_Type_Conversion
5676 and then Is_Entity_Name (Expression (R))
5677 and then Entity (L) = Entity (Expression (R)))))
5681 and then Ekind (Entity (R)) = E_Constant
5682 and then Nkind (L) = N_Type_Conversion
5683 and then Is_Entity_Name (Expression (L))
5684 and then Entity (R) = Entity (Expression (L)))
5688 and then Is_Entity_Name (R)
5689 and then Entity (L) = Entity (R)
5690 and then Ekind (Entity (L)) = E_In_Parameter
5691 and then Inside_Init_Proc);
5694 -- Start of processing for Selected_Length_Checks
5697 if not Expander_Active then
5701 if Target_Typ = Any_Type
5702 or else Target_Typ = Any_Composite
5703 or else Raises_Constraint_Error (Ck_Node)
5712 T_Typ := Target_Typ;
5714 if No (Source_Typ) then
5715 S_Typ := Etype (Ck_Node);
5717 S_Typ := Source_Typ;
5720 if S_Typ = Any_Type or else S_Typ = Any_Composite then
5724 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
5725 S_Typ := Designated_Type (S_Typ);
5726 T_Typ := Designated_Type (T_Typ);
5729 -- A simple optimization for the null case
5731 if Known_Null (Ck_Node) then
5736 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
5737 if Is_Constrained (T_Typ) then
5739 -- The checking code to be generated will freeze the
5740 -- corresponding array type. However, we must freeze the
5741 -- type now, so that the freeze node does not appear within
5742 -- the generated condional expression, but ahead of it.
5744 Freeze_Before (Ck_Node, T_Typ);
5746 Expr_Actual := Get_Referenced_Object (Ck_Node);
5747 Exptyp := Get_Actual_Subtype (Ck_Node);
5749 if Is_Access_Type (Exptyp) then
5750 Exptyp := Designated_Type (Exptyp);
5753 -- String_Literal case. This needs to be handled specially be-
5754 -- cause no index types are available for string literals. The
5755 -- condition is simply:
5757 -- T_Typ'Length = string-literal-length
5759 if Nkind (Expr_Actual) = N_String_Literal
5760 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
5764 Left_Opnd => Get_E_Length (T_Typ, 1),
5766 Make_Integer_Literal (Loc,
5768 String_Literal_Length (Etype (Expr_Actual))));
5770 -- General array case. Here we have a usable actual subtype for
5771 -- the expression, and the condition is built from the two types
5774 -- T_Typ'Length /= Exptyp'Length or else
5775 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
5776 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
5779 elsif Is_Constrained (Exptyp) then
5781 Ndims : constant Nat := Number_Dimensions (T_Typ);
5794 -- At the library level, we need to ensure that the type of
5795 -- the object is elaborated before the check itself is
5796 -- emitted. This is only done if the object is in the
5797 -- current compilation unit, otherwise the type is frozen
5798 -- and elaborated in its unit.
5800 if Is_Itype (Exptyp)
5802 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
5804 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
5805 and then In_Open_Scopes (Scope (Exptyp))
5807 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
5808 Set_Itype (Ref_Node, Exptyp);
5809 Insert_Action (Ck_Node, Ref_Node);
5812 L_Index := First_Index (T_Typ);
5813 R_Index := First_Index (Exptyp);
5815 for Indx in 1 .. Ndims loop
5816 if not (Nkind (L_Index) = N_Raise_Constraint_Error
5818 Nkind (R_Index) = N_Raise_Constraint_Error)
5820 Get_Index_Bounds (L_Index, L_Low, L_High);
5821 Get_Index_Bounds (R_Index, R_Low, R_High);
5823 -- Deal with compile time length check. Note that we
5824 -- skip this in the access case, because the access
5825 -- value may be null, so we cannot know statically.
5828 and then Compile_Time_Known_Value (L_Low)
5829 and then Compile_Time_Known_Value (L_High)
5830 and then Compile_Time_Known_Value (R_Low)
5831 and then Compile_Time_Known_Value (R_High)
5833 if Expr_Value (L_High) >= Expr_Value (L_Low) then
5834 L_Length := Expr_Value (L_High) -
5835 Expr_Value (L_Low) + 1;
5837 L_Length := UI_From_Int (0);
5840 if Expr_Value (R_High) >= Expr_Value (R_Low) then
5841 R_Length := Expr_Value (R_High) -
5842 Expr_Value (R_Low) + 1;
5844 R_Length := UI_From_Int (0);
5847 if L_Length > R_Length then
5849 (Compile_Time_Constraint_Error
5850 (Wnode, "too few elements for}?", T_Typ));
5852 elsif L_Length < R_Length then
5854 (Compile_Time_Constraint_Error
5855 (Wnode, "too many elements for}?", T_Typ));
5858 -- The comparison for an individual index subtype
5859 -- is omitted if the corresponding index subtypes
5860 -- statically match, since the result is known to
5861 -- be true. Note that this test is worth while even
5862 -- though we do static evaluation, because non-static
5863 -- subtypes can statically match.
5866 Subtypes_Statically_Match
5867 (Etype (L_Index), Etype (R_Index))
5870 (Same_Bounds (L_Low, R_Low)
5871 and then Same_Bounds (L_High, R_High))
5874 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
5883 -- Handle cases where we do not get a usable actual subtype that
5884 -- is constrained. This happens for example in the function call
5885 -- and explicit dereference cases. In these cases, we have to get
5886 -- the length or range from the expression itself, making sure we
5887 -- do not evaluate it more than once.
5889 -- Here Ck_Node is the original expression, or more properly the
5890 -- result of applying Duplicate_Expr to the original tree, forcing
5891 -- the result to be a name.
5895 Ndims : constant Nat := Number_Dimensions (T_Typ);
5898 -- Build the condition for the explicit dereference case
5900 for Indx in 1 .. Ndims loop
5902 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
5909 -- Construct the test and insert into the tree
5911 if Present (Cond) then
5913 Cond := Guard_Access (Cond, Loc, Ck_Node);
5917 (Make_Raise_Constraint_Error (Loc,
5919 Reason => CE_Length_Check_Failed));
5923 end Selected_Length_Checks;
5925 ---------------------------
5926 -- Selected_Range_Checks --
5927 ---------------------------
5929 function Selected_Range_Checks
5931 Target_Typ : Entity_Id;
5932 Source_Typ : Entity_Id;
5933 Warn_Node : Node_Id) return Check_Result
5935 Loc : constant Source_Ptr := Sloc (Ck_Node);
5938 Expr_Actual : Node_Id;
5940 Cond : Node_Id := Empty;
5941 Do_Access : Boolean := False;
5942 Wnode : Node_Id := Warn_Node;
5943 Ret_Result : Check_Result := (Empty, Empty);
5944 Num_Checks : Integer := 0;
5946 procedure Add_Check (N : Node_Id);
5947 -- Adds the action given to Ret_Result if N is non-Empty
5949 function Discrete_Range_Cond
5951 Typ : Entity_Id) return Node_Id;
5952 -- Returns expression to compute:
5953 -- Low_Bound (Expr) < Typ'First
5955 -- High_Bound (Expr) > Typ'Last
5957 function Discrete_Expr_Cond
5959 Typ : Entity_Id) return Node_Id;
5960 -- Returns expression to compute:
5965 function Get_E_First_Or_Last
5968 Nam : Name_Id) return Node_Id;
5969 -- Returns expression to compute:
5970 -- E'First or E'Last
5972 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
5973 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
5974 -- Returns expression to compute:
5975 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
5977 function Range_E_Cond
5978 (Exptyp : Entity_Id;
5982 -- Returns expression to compute:
5983 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
5985 function Range_Equal_E_Cond
5986 (Exptyp : Entity_Id;
5988 Indx : Nat) return Node_Id;
5989 -- Returns expression to compute:
5990 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
5992 function Range_N_Cond
5995 Indx : Nat) return Node_Id;
5996 -- Return expression to compute:
5997 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
6003 procedure Add_Check (N : Node_Id) is
6007 -- For now, ignore attempt to place more than 2 checks ???
6009 if Num_Checks = 2 then
6013 pragma Assert (Num_Checks <= 1);
6014 Num_Checks := Num_Checks + 1;
6015 Ret_Result (Num_Checks) := N;
6019 -------------------------
6020 -- Discrete_Expr_Cond --
6021 -------------------------
6023 function Discrete_Expr_Cond
6025 Typ : Entity_Id) return Node_Id
6033 Convert_To (Base_Type (Typ),
6034 Duplicate_Subexpr_No_Checks (Expr)),
6036 Convert_To (Base_Type (Typ),
6037 Get_E_First_Or_Last (Typ, 0, Name_First))),
6042 Convert_To (Base_Type (Typ),
6043 Duplicate_Subexpr_No_Checks (Expr)),
6047 Get_E_First_Or_Last (Typ, 0, Name_Last))));
6048 end Discrete_Expr_Cond;
6050 -------------------------
6051 -- Discrete_Range_Cond --
6052 -------------------------
6054 function Discrete_Range_Cond
6056 Typ : Entity_Id) return Node_Id
6058 LB : Node_Id := Low_Bound (Expr);
6059 HB : Node_Id := High_Bound (Expr);
6061 Left_Opnd : Node_Id;
6062 Right_Opnd : Node_Id;
6065 if Nkind (LB) = N_Identifier
6066 and then Ekind (Entity (LB)) = E_Discriminant
6068 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6071 if Nkind (HB) = N_Identifier
6072 and then Ekind (Entity (HB)) = E_Discriminant
6074 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6081 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
6085 (Base_Type (Typ), Get_E_First_Or_Last (Typ, 0, Name_First)));
6087 if Base_Type (Typ) = Typ then
6090 elsif Compile_Time_Known_Value (High_Bound (Scalar_Range (Typ)))
6092 Compile_Time_Known_Value (High_Bound (Scalar_Range
6095 if Is_Floating_Point_Type (Typ) then
6096 if Expr_Value_R (High_Bound (Scalar_Range (Typ))) =
6097 Expr_Value_R (High_Bound (Scalar_Range (Base_Type (Typ))))
6103 if Expr_Value (High_Bound (Scalar_Range (Typ))) =
6104 Expr_Value (High_Bound (Scalar_Range (Base_Type (Typ))))
6115 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
6120 Get_E_First_Or_Last (Typ, 0, Name_Last)));
6122 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
6123 end Discrete_Range_Cond;
6125 -------------------------
6126 -- Get_E_First_Or_Last --
6127 -------------------------
6129 function Get_E_First_Or_Last
6132 Nam : Name_Id) return Node_Id
6140 if Is_Array_Type (E) then
6141 N := First_Index (E);
6143 for J in 2 .. Indx loop
6148 N := Scalar_Range (E);
6151 if Nkind (N) = N_Subtype_Indication then
6152 LB := Low_Bound (Range_Expression (Constraint (N)));
6153 HB := High_Bound (Range_Expression (Constraint (N)));
6155 elsif Is_Entity_Name (N) then
6156 LB := Type_Low_Bound (Etype (N));
6157 HB := Type_High_Bound (Etype (N));
6160 LB := Low_Bound (N);
6161 HB := High_Bound (N);
6164 if Nam = Name_First then
6170 if Nkind (Bound) = N_Identifier
6171 and then Ekind (Entity (Bound)) = E_Discriminant
6173 -- If this is a task discriminant, and we are the body, we must
6174 -- retrieve the corresponding body discriminal. This is another
6175 -- consequence of the early creation of discriminals, and the
6176 -- need to generate constraint checks before their declarations
6177 -- are made visible.
6179 if Is_Concurrent_Record_Type (Scope (Entity (Bound))) then
6181 Tsk : constant Entity_Id :=
6182 Corresponding_Concurrent_Type
6183 (Scope (Entity (Bound)));
6187 if In_Open_Scopes (Tsk)
6188 and then Has_Completion (Tsk)
6190 -- Find discriminant of original task, and use its
6191 -- current discriminal, which is the renaming within
6194 Disc := First_Discriminant (Tsk);
6195 while Present (Disc) loop
6196 if Chars (Disc) = Chars (Entity (Bound)) then
6197 Set_Scope (Discriminal (Disc), Tsk);
6198 return New_Occurrence_Of (Discriminal (Disc), Loc);
6201 Next_Discriminant (Disc);
6204 -- That loop should always succeed in finding a matching
6205 -- entry and returning. Fatal error if not.
6207 raise Program_Error;
6211 New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6215 return New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6218 elsif Nkind (Bound) = N_Identifier
6219 and then Ekind (Entity (Bound)) = E_In_Parameter
6220 and then not Inside_Init_Proc
6222 return Get_Discriminal (E, Bound);
6224 elsif Nkind (Bound) = N_Integer_Literal then
6225 return Make_Integer_Literal (Loc, Intval (Bound));
6227 -- Case of a bound rewritten to an N_Raise_Constraint_Error node
6228 -- because it is an out-of-range value. Duplicate_Subexpr cannot be
6229 -- called on this node because an N_Raise_Constraint_Error is not
6230 -- side effect free, and we may not assume that we are in the proper
6231 -- context to remove side effects on it at the point of reference.
6233 elsif Nkind (Bound) = N_Raise_Constraint_Error then
6234 return New_Copy_Tree (Bound);
6237 return Duplicate_Subexpr_No_Checks (Bound);
6239 end Get_E_First_Or_Last;
6245 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
6248 Make_Attribute_Reference (Loc,
6249 Attribute_Name => Name_First,
6251 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6252 Expressions => New_List (
6253 Make_Integer_Literal (Loc, Indx)));
6260 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
6263 Make_Attribute_Reference (Loc,
6264 Attribute_Name => Name_Last,
6266 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6267 Expressions => New_List (
6268 Make_Integer_Literal (Loc, Indx)));
6275 function Range_E_Cond
6276 (Exptyp : Entity_Id;
6278 Indx : Nat) return Node_Id
6285 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6286 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6290 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6291 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6294 ------------------------
6295 -- Range_Equal_E_Cond --
6296 ------------------------
6298 function Range_Equal_E_Cond
6299 (Exptyp : Entity_Id;
6301 Indx : Nat) return Node_Id
6308 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6309 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6312 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6313 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6314 end Range_Equal_E_Cond;
6320 function Range_N_Cond
6323 Indx : Nat) return Node_Id
6330 Left_Opnd => Get_N_First (Expr, Indx),
6331 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6335 Left_Opnd => Get_N_Last (Expr, Indx),
6336 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6339 -- Start of processing for Selected_Range_Checks
6342 if not Expander_Active then
6346 if Target_Typ = Any_Type
6347 or else Target_Typ = Any_Composite
6348 or else Raises_Constraint_Error (Ck_Node)
6357 T_Typ := Target_Typ;
6359 if No (Source_Typ) then
6360 S_Typ := Etype (Ck_Node);
6362 S_Typ := Source_Typ;
6365 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6369 -- The order of evaluating T_Typ before S_Typ seems to be critical
6370 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
6371 -- in, and since Node can be an N_Range node, it might be invalid.
6372 -- Should there be an assert check somewhere for taking the Etype of
6373 -- an N_Range node ???
6375 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6376 S_Typ := Designated_Type (S_Typ);
6377 T_Typ := Designated_Type (T_Typ);
6380 -- A simple optimization for the null case
6382 if Known_Null (Ck_Node) then
6387 -- For an N_Range Node, check for a null range and then if not
6388 -- null generate a range check action.
6390 if Nkind (Ck_Node) = N_Range then
6392 -- There's no point in checking a range against itself
6394 if Ck_Node = Scalar_Range (T_Typ) then
6399 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
6400 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
6401 LB : constant Node_Id := Low_Bound (Ck_Node);
6402 HB : constant Node_Id := High_Bound (Ck_Node);
6403 Null_Range : Boolean;
6405 Out_Of_Range_L : Boolean;
6406 Out_Of_Range_H : Boolean;
6409 -- Check for case where everything is static and we can
6410 -- do the check at compile time. This is skipped if we
6411 -- have an access type, since the access value may be null.
6413 -- ??? This code can be improved since you only need to know
6414 -- that the two respective bounds (LB & T_LB or HB & T_HB)
6415 -- are known at compile time to emit pertinent messages.
6417 if Compile_Time_Known_Value (LB)
6418 and then Compile_Time_Known_Value (HB)
6419 and then Compile_Time_Known_Value (T_LB)
6420 and then Compile_Time_Known_Value (T_HB)
6421 and then not Do_Access
6423 -- Floating-point case
6425 if Is_Floating_Point_Type (S_Typ) then
6426 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
6428 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
6430 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
6433 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
6435 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
6437 -- Fixed or discrete type case
6440 Null_Range := Expr_Value (HB) < Expr_Value (LB);
6442 (Expr_Value (LB) < Expr_Value (T_LB))
6444 (Expr_Value (LB) > Expr_Value (T_HB));
6447 (Expr_Value (HB) > Expr_Value (T_HB))
6449 (Expr_Value (HB) < Expr_Value (T_LB));
6452 if not Null_Range then
6453 if Out_Of_Range_L then
6454 if No (Warn_Node) then
6456 (Compile_Time_Constraint_Error
6457 (Low_Bound (Ck_Node),
6458 "static value out of range of}?", T_Typ));
6462 (Compile_Time_Constraint_Error
6464 "static range out of bounds of}?", T_Typ));
6468 if Out_Of_Range_H then
6469 if No (Warn_Node) then
6471 (Compile_Time_Constraint_Error
6472 (High_Bound (Ck_Node),
6473 "static value out of range of}?", T_Typ));
6477 (Compile_Time_Constraint_Error
6479 "static range out of bounds of}?", T_Typ));
6487 LB : Node_Id := Low_Bound (Ck_Node);
6488 HB : Node_Id := High_Bound (Ck_Node);
6491 -- If either bound is a discriminant and we are within the
6492 -- record declaration, it is a use of the discriminant in a
6493 -- constraint of a component, and nothing can be checked
6494 -- here. The check will be emitted within the init proc.
6495 -- Before then, the discriminal has no real meaning.
6496 -- Similarly, if the entity is a discriminal, there is no
6497 -- check to perform yet.
6499 -- The same holds within a discriminated synchronized type,
6500 -- where the discriminant may constrain a component or an
6503 if Nkind (LB) = N_Identifier
6504 and then Denotes_Discriminant (LB, True)
6506 if Current_Scope = Scope (Entity (LB))
6507 or else Is_Concurrent_Type (Current_Scope)
6508 or else Ekind (Entity (LB)) /= E_Discriminant
6513 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6517 if Nkind (HB) = N_Identifier
6518 and then Denotes_Discriminant (HB, True)
6520 if Current_Scope = Scope (Entity (HB))
6521 or else Is_Concurrent_Type (Current_Scope)
6522 or else Ekind (Entity (HB)) /= E_Discriminant
6527 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6531 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
6532 Set_Paren_Count (Cond, 1);
6538 Left_Opnd => Duplicate_Subexpr_No_Checks (HB),
6539 Right_Opnd => Duplicate_Subexpr_No_Checks (LB)),
6540 Right_Opnd => Cond);
6545 elsif Is_Scalar_Type (S_Typ) then
6547 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
6548 -- except the above simply sets a flag in the node and lets
6549 -- gigi generate the check base on the Etype of the expression.
6550 -- Sometimes, however we want to do a dynamic check against an
6551 -- arbitrary target type, so we do that here.
6553 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
6554 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6556 -- For literals, we can tell if the constraint error will be
6557 -- raised at compile time, so we never need a dynamic check, but
6558 -- if the exception will be raised, then post the usual warning,
6559 -- and replace the literal with a raise constraint error
6560 -- expression. As usual, skip this for access types
6562 elsif Compile_Time_Known_Value (Ck_Node)
6563 and then not Do_Access
6566 LB : constant Node_Id := Type_Low_Bound (T_Typ);
6567 UB : constant Node_Id := Type_High_Bound (T_Typ);
6569 Out_Of_Range : Boolean;
6570 Static_Bounds : constant Boolean :=
6571 Compile_Time_Known_Value (LB)
6572 and Compile_Time_Known_Value (UB);
6575 -- Following range tests should use Sem_Eval routine ???
6577 if Static_Bounds then
6578 if Is_Floating_Point_Type (S_Typ) then
6580 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
6582 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
6584 else -- fixed or discrete type
6586 Expr_Value (Ck_Node) < Expr_Value (LB)
6588 Expr_Value (Ck_Node) > Expr_Value (UB);
6591 -- Bounds of the type are static and the literal is
6592 -- out of range so make a warning message.
6594 if Out_Of_Range then
6595 if No (Warn_Node) then
6597 (Compile_Time_Constraint_Error
6599 "static value out of range of}?", T_Typ));
6603 (Compile_Time_Constraint_Error
6605 "static value out of range of}?", T_Typ));
6610 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6614 -- Here for the case of a non-static expression, we need a runtime
6615 -- check unless the source type range is guaranteed to be in the
6616 -- range of the target type.
6619 if not In_Subrange_Of (S_Typ, T_Typ) then
6620 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6625 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6626 if Is_Constrained (T_Typ) then
6628 Expr_Actual := Get_Referenced_Object (Ck_Node);
6629 Exptyp := Get_Actual_Subtype (Expr_Actual);
6631 if Is_Access_Type (Exptyp) then
6632 Exptyp := Designated_Type (Exptyp);
6635 -- String_Literal case. This needs to be handled specially be-
6636 -- cause no index types are available for string literals. The
6637 -- condition is simply:
6639 -- T_Typ'Length = string-literal-length
6641 if Nkind (Expr_Actual) = N_String_Literal then
6644 -- General array case. Here we have a usable actual subtype for
6645 -- the expression, and the condition is built from the two types
6647 -- T_Typ'First < Exptyp'First or else
6648 -- T_Typ'Last > Exptyp'Last or else
6649 -- T_Typ'First(1) < Exptyp'First(1) or else
6650 -- T_Typ'Last(1) > Exptyp'Last(1) or else
6653 elsif Is_Constrained (Exptyp) then
6655 Ndims : constant Nat := Number_Dimensions (T_Typ);
6665 L_Index := First_Index (T_Typ);
6666 R_Index := First_Index (Exptyp);
6668 for Indx in 1 .. Ndims loop
6669 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6671 Nkind (R_Index) = N_Raise_Constraint_Error)
6673 Get_Index_Bounds (L_Index, L_Low, L_High);
6674 Get_Index_Bounds (R_Index, R_Low, R_High);
6676 -- Deal with compile time length check. Note that we
6677 -- skip this in the access case, because the access
6678 -- value may be null, so we cannot know statically.
6681 Subtypes_Statically_Match
6682 (Etype (L_Index), Etype (R_Index))
6684 -- If the target type is constrained then we
6685 -- have to check for exact equality of bounds
6686 -- (required for qualified expressions).
6688 if Is_Constrained (T_Typ) then
6691 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
6695 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
6706 -- Handle cases where we do not get a usable actual subtype that
6707 -- is constrained. This happens for example in the function call
6708 -- and explicit dereference cases. In these cases, we have to get
6709 -- the length or range from the expression itself, making sure we
6710 -- do not evaluate it more than once.
6712 -- Here Ck_Node is the original expression, or more properly the
6713 -- result of applying Duplicate_Expr to the original tree,
6714 -- forcing the result to be a name.
6718 Ndims : constant Nat := Number_Dimensions (T_Typ);
6721 -- Build the condition for the explicit dereference case
6723 for Indx in 1 .. Ndims loop
6725 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
6732 -- For a conversion to an unconstrained array type, generate an
6733 -- Action to check that the bounds of the source value are within
6734 -- the constraints imposed by the target type (RM 4.6(38)). No
6735 -- check is needed for a conversion to an access to unconstrained
6736 -- array type, as 4.6(24.15/2) requires the designated subtypes
6737 -- of the two access types to statically match.
6739 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
6740 and then not Do_Access
6743 Opnd_Index : Node_Id;
6744 Targ_Index : Node_Id;
6745 Opnd_Range : Node_Id;
6748 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
6749 Targ_Index := First_Index (T_Typ);
6751 while Present (Opnd_Index) loop
6753 -- If the index is a range, use its bounds. If it is an
6754 -- entity (as will be the case if it is a named subtype
6755 -- or an itype created for a slice) retrieve its range.
6757 if Is_Entity_Name (Opnd_Index)
6758 and then Is_Type (Entity (Opnd_Index))
6760 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
6762 Opnd_Range := Opnd_Index;
6765 if Nkind (Opnd_Range) = N_Range then
6767 (Low_Bound (Opnd_Range), Etype (Targ_Index))
6770 (High_Bound (Opnd_Range), Etype (Targ_Index))
6774 -- If null range, no check needed
6777 Compile_Time_Known_Value (High_Bound (Opnd_Range))
6779 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
6781 Expr_Value (High_Bound (Opnd_Range)) <
6782 Expr_Value (Low_Bound (Opnd_Range))
6786 elsif Is_Out_Of_Range
6787 (Low_Bound (Opnd_Range), Etype (Targ_Index))
6790 (High_Bound (Opnd_Range), Etype (Targ_Index))
6793 (Compile_Time_Constraint_Error
6794 (Wnode, "value out of range of}?", T_Typ));
6800 (Opnd_Range, Etype (Targ_Index)));
6804 Next_Index (Opnd_Index);
6805 Next_Index (Targ_Index);
6812 -- Construct the test and insert into the tree
6814 if Present (Cond) then
6816 Cond := Guard_Access (Cond, Loc, Ck_Node);
6820 (Make_Raise_Constraint_Error (Loc,
6822 Reason => CE_Range_Check_Failed));
6826 end Selected_Range_Checks;
6828 -------------------------------
6829 -- Storage_Checks_Suppressed --
6830 -------------------------------
6832 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
6834 if Present (E) and then Checks_May_Be_Suppressed (E) then
6835 return Is_Check_Suppressed (E, Storage_Check);
6837 return Scope_Suppress (Storage_Check);
6839 end Storage_Checks_Suppressed;
6841 ---------------------------
6842 -- Tag_Checks_Suppressed --
6843 ---------------------------
6845 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
6848 if Kill_Tag_Checks (E) then
6850 elsif Checks_May_Be_Suppressed (E) then
6851 return Is_Check_Suppressed (E, Tag_Check);
6855 return Scope_Suppress (Tag_Check);
6856 end Tag_Checks_Suppressed;
6858 --------------------------
6859 -- Validity_Check_Range --
6860 --------------------------
6862 procedure Validity_Check_Range (N : Node_Id) is
6864 if Validity_Checks_On and Validity_Check_Operands then
6865 if Nkind (N) = N_Range then
6866 Ensure_Valid (Low_Bound (N));
6867 Ensure_Valid (High_Bound (N));
6870 end Validity_Check_Range;
6872 --------------------------------
6873 -- Validity_Checks_Suppressed --
6874 --------------------------------
6876 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
6878 if Present (E) and then Checks_May_Be_Suppressed (E) then
6879 return Is_Check_Suppressed (E, Validity_Check);
6881 return Scope_Suppress (Validity_Check);
6883 end Validity_Checks_Suppressed;