1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2008, 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))",
546 Set_Address_Warning_Posted (AC);
548 end Compile_Time_Bad_Alignment;
550 -- Start of processing for Apply_Address_Clause_Check
553 -- First obtain expression from address clause
555 Expr := Expression (AC);
557 -- The following loop digs for the real expression to use in the check
560 -- For constant, get constant expression
562 if Is_Entity_Name (Expr)
563 and then Ekind (Entity (Expr)) = E_Constant
565 Expr := Constant_Value (Entity (Expr));
567 -- For unchecked conversion, get result to convert
569 elsif Nkind (Expr) = N_Unchecked_Type_Conversion then
570 Expr := Expression (Expr);
572 -- For (common case) of To_Address call, get argument
574 elsif Nkind (Expr) = N_Function_Call
575 and then Is_Entity_Name (Name (Expr))
576 and then Is_RTE (Entity (Name (Expr)), RE_To_Address)
578 Expr := First (Parameter_Associations (Expr));
580 if Nkind (Expr) = N_Parameter_Association then
581 Expr := Explicit_Actual_Parameter (Expr);
584 -- We finally have the real expression
591 -- Output a warning if we have the situation of
593 -- for X'Address use Y'Address
595 -- and X and Y both have known object sizes, and Y is smaller than X
597 if Nkind (Expr) = N_Attribute_Reference
598 and then Attribute_Name (Expr) = Name_Address
599 and then Is_Entity_Name (Prefix (Expr))
602 Exp_Ent : constant Entity_Id := Entity (Prefix (Expr));
603 Obj_Size : Uint := No_Uint;
604 Exp_Size : Uint := No_Uint;
607 if Known_Esize (E) then
608 Obj_Size := Esize (E);
609 elsif Known_Esize (Etype (E)) then
610 Obj_Size := Esize (Etype (E));
613 if Known_Esize (Exp_Ent) then
614 Exp_Size := Esize (Exp_Ent);
615 elsif Known_Esize (Etype (Exp_Ent)) then
616 Exp_Size := Esize (Etype (Exp_Ent));
619 if Obj_Size /= No_Uint
620 and then Exp_Size /= No_Uint
621 and then Obj_Size > Exp_Size
622 and then not Has_Warnings_Off (E)
624 if Address_Clause_Overlay_Warnings then
626 ("?& overlays smaller object", Aexp, E);
628 ("\?program execution may be erroneous", Aexp, E);
629 Size_Warning_Output := True;
630 Set_Address_Warning_Posted (AC);
636 -- See if alignment check needed. Note that we never need a check if the
637 -- maximum alignment is one, since the check will always succeed.
639 -- Note: we do not check for checks suppressed here, since that check
640 -- was done in Sem_Ch13 when the address clause was processed. We are
641 -- only called if checks were not suppressed. The reason for this is
642 -- that we have to delay the call to Apply_Alignment_Check till freeze
643 -- time (so that all types etc are elaborated), but we have to check
644 -- the status of check suppressing at the point of the address clause.
647 or else not Check_Address_Alignment (AC)
648 or else Maximum_Alignment = 1
653 -- See if we know that Expr is a bad alignment at compile time
655 if Compile_Time_Known_Value (Expr)
656 and then (Known_Alignment (E) or else Known_Alignment (Typ))
659 AL : Uint := Alignment (Typ);
662 -- The object alignment might be more restrictive than the
665 if Known_Alignment (E) then
669 if Expr_Value (Expr) mod AL /= 0 then
670 Compile_Time_Bad_Alignment;
676 -- If the expression has the form X'Address, then we can find out if
677 -- the object X has an alignment that is compatible with the object E.
679 elsif Nkind (Expr) = N_Attribute_Reference
680 and then Attribute_Name (Expr) = Name_Address
683 AR : constant Alignment_Result :=
684 Has_Compatible_Alignment (E, Prefix (Expr));
686 if AR = Known_Compatible then
688 elsif AR = Known_Incompatible then
689 Compile_Time_Bad_Alignment;
694 -- Here we do not know if the value is acceptable. Stricly we don't have
695 -- to do anything, since if the alignment is bad, we have an erroneous
696 -- program. However we are allowed to check for erroneous conditions and
697 -- we decide to do this by default if the check is not suppressed.
699 -- However, don't do the check if elaboration code is unwanted
701 if Restriction_Active (No_Elaboration_Code) then
704 -- Generate a check to raise PE if alignment may be inappropriate
707 -- If the original expression is a non-static constant, use the
708 -- name of the constant itself rather than duplicating its
709 -- defining expression, which was extracted above.
711 -- Note: Expr is empty if the address-clause is applied to in-mode
712 -- actuals (allowed by 13.1(22)).
714 if not Present (Expr)
716 (Is_Entity_Name (Expression (AC))
717 and then Ekind (Entity (Expression (AC))) = E_Constant
718 and then Nkind (Parent (Entity (Expression (AC))))
719 = N_Object_Declaration)
721 Expr := New_Copy_Tree (Expression (AC));
723 Remove_Side_Effects (Expr);
726 Insert_After_And_Analyze (N,
727 Make_Raise_Program_Error (Loc,
734 (RTE (RE_Integer_Address), Expr),
736 Make_Attribute_Reference (Loc,
737 Prefix => New_Occurrence_Of (E, Loc),
738 Attribute_Name => Name_Alignment)),
739 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
740 Reason => PE_Misaligned_Address_Value),
741 Suppress => All_Checks);
746 -- If we have some missing run time component in configurable run time
747 -- mode then just skip the check (it is not required in any case).
749 when RE_Not_Available =>
751 end Apply_Address_Clause_Check;
753 -------------------------------------
754 -- Apply_Arithmetic_Overflow_Check --
755 -------------------------------------
757 -- This routine is called only if the type is an integer type, and
758 -- a software arithmetic overflow check must be performed for op
759 -- (add, subtract, multiply). The check is performed only if
760 -- Software_Overflow_Checking is enabled and Do_Overflow_Check
761 -- is set. In this case we expand the operation into a more complex
762 -- sequence of tests that ensures that overflow is properly caught.
764 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
765 Loc : constant Source_Ptr := Sloc (N);
766 Typ : constant Entity_Id := Etype (N);
767 Rtyp : constant Entity_Id := Root_Type (Typ);
768 Siz : constant Int := UI_To_Int (Esize (Rtyp));
769 Dsiz : constant Int := Siz * 2;
776 -- Skip this if overflow checks are done in back end, or the overflow
777 -- flag is not set anyway, or we are not doing code expansion.
778 -- Special case CLI target, where arithmetic overflow checks can be
779 -- performed for integer and long_integer
781 if Backend_Overflow_Checks_On_Target
782 or else (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
783 or else not Do_Overflow_Check (N)
784 or else not Expander_Active
789 -- Otherwise, we generate the full general code for front end overflow
790 -- detection, which works by doing arithmetic in a larger type:
796 -- Typ (Checktyp (x) op Checktyp (y));
798 -- where Typ is the type of the original expression, and Checktyp is
799 -- an integer type of sufficient length to hold the largest possible
802 -- In the case where check type exceeds the size of Long_Long_Integer,
803 -- we use a different approach, expanding to:
805 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
807 -- where xxx is Add, Multiply or Subtract as appropriate
809 -- Find check type if one exists
811 if Dsiz <= Standard_Integer_Size then
812 Ctyp := Standard_Integer;
814 elsif Dsiz <= Standard_Long_Long_Integer_Size then
815 Ctyp := Standard_Long_Long_Integer;
817 -- No check type exists, use runtime call
820 if Nkind (N) = N_Op_Add then
821 Cent := RE_Add_With_Ovflo_Check;
823 elsif Nkind (N) = N_Op_Multiply then
824 Cent := RE_Multiply_With_Ovflo_Check;
827 pragma Assert (Nkind (N) = N_Op_Subtract);
828 Cent := RE_Subtract_With_Ovflo_Check;
833 Make_Function_Call (Loc,
834 Name => New_Reference_To (RTE (Cent), Loc),
835 Parameter_Associations => New_List (
836 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
837 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
839 Analyze_And_Resolve (N, Typ);
843 -- If we fall through, we have the case where we do the arithmetic in
844 -- the next higher type and get the check by conversion. In these cases
845 -- Ctyp is set to the type to be used as the check type.
847 Opnod := Relocate_Node (N);
849 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
852 Set_Etype (Opnd, Ctyp);
853 Set_Analyzed (Opnd, True);
854 Set_Left_Opnd (Opnod, Opnd);
856 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
859 Set_Etype (Opnd, Ctyp);
860 Set_Analyzed (Opnd, True);
861 Set_Right_Opnd (Opnod, Opnd);
863 -- The type of the operation changes to the base type of the check type,
864 -- and we reset the overflow check indication, since clearly no overflow
865 -- is possible now that we are using a double length type. We also set
866 -- the Analyzed flag to avoid a recursive attempt to expand the node.
868 Set_Etype (Opnod, Base_Type (Ctyp));
869 Set_Do_Overflow_Check (Opnod, False);
870 Set_Analyzed (Opnod, True);
872 -- Now build the outer conversion
874 Opnd := OK_Convert_To (Typ, Opnod);
876 Set_Etype (Opnd, Typ);
878 -- In the discrete type case, we directly generate the range check for
879 -- the outer operand. This range check will implement the required
882 if Is_Discrete_Type (Typ) then
884 Generate_Range_Check (Expression (N), Typ, CE_Overflow_Check_Failed);
886 -- For other types, we enable overflow checking on the conversion,
887 -- after setting the node as analyzed to prevent recursive attempts
888 -- to expand the conversion node.
891 Set_Analyzed (Opnd, True);
892 Enable_Overflow_Check (Opnd);
897 when RE_Not_Available =>
899 end Apply_Arithmetic_Overflow_Check;
901 ----------------------------
902 -- Apply_Constraint_Check --
903 ----------------------------
905 procedure Apply_Constraint_Check
908 No_Sliding : Boolean := False)
910 Desig_Typ : Entity_Id;
913 if Inside_A_Generic then
916 elsif Is_Scalar_Type (Typ) then
917 Apply_Scalar_Range_Check (N, Typ);
919 elsif Is_Array_Type (Typ) then
921 -- A useful optimization: an aggregate with only an others clause
922 -- always has the right bounds.
924 if Nkind (N) = N_Aggregate
925 and then No (Expressions (N))
927 (First (Choices (First (Component_Associations (N)))))
933 if Is_Constrained (Typ) then
934 Apply_Length_Check (N, Typ);
937 Apply_Range_Check (N, Typ);
940 Apply_Range_Check (N, Typ);
943 elsif (Is_Record_Type (Typ)
944 or else Is_Private_Type (Typ))
945 and then Has_Discriminants (Base_Type (Typ))
946 and then Is_Constrained (Typ)
948 Apply_Discriminant_Check (N, Typ);
950 elsif Is_Access_Type (Typ) then
952 Desig_Typ := Designated_Type (Typ);
954 -- No checks necessary if expression statically null
956 if Known_Null (N) then
957 if Can_Never_Be_Null (Typ) then
958 Install_Null_Excluding_Check (N);
961 -- No sliding possible on access to arrays
963 elsif Is_Array_Type (Desig_Typ) then
964 if Is_Constrained (Desig_Typ) then
965 Apply_Length_Check (N, Typ);
968 Apply_Range_Check (N, Typ);
970 elsif Has_Discriminants (Base_Type (Desig_Typ))
971 and then Is_Constrained (Desig_Typ)
973 Apply_Discriminant_Check (N, Typ);
976 -- Apply the the 2005 Null_Excluding check. Note that we do not apply
977 -- this check if the constraint node is illegal, as shown by having
978 -- an error posted. This additional guard prevents cascaded errors
979 -- and compiler aborts on illegal programs involving Ada 2005 checks.
981 if Can_Never_Be_Null (Typ)
982 and then not Can_Never_Be_Null (Etype (N))
983 and then not Error_Posted (N)
985 Install_Null_Excluding_Check (N);
988 end Apply_Constraint_Check;
990 ------------------------------
991 -- Apply_Discriminant_Check --
992 ------------------------------
994 procedure Apply_Discriminant_Check
997 Lhs : Node_Id := Empty)
999 Loc : constant Source_Ptr := Sloc (N);
1000 Do_Access : constant Boolean := Is_Access_Type (Typ);
1001 S_Typ : Entity_Id := Etype (N);
1005 function Is_Aliased_Unconstrained_Component return Boolean;
1006 -- It is possible for an aliased component to have a nominal
1007 -- unconstrained subtype (through instantiation). If this is a
1008 -- discriminated component assigned in the expansion of an aggregate
1009 -- in an initialization, the check must be suppressed. This unusual
1010 -- situation requires a predicate of its own.
1012 ----------------------------------------
1013 -- Is_Aliased_Unconstrained_Component --
1014 ----------------------------------------
1016 function Is_Aliased_Unconstrained_Component return Boolean is
1021 if Nkind (Lhs) /= N_Selected_Component then
1024 Comp := Entity (Selector_Name (Lhs));
1025 Pref := Prefix (Lhs);
1028 if Ekind (Comp) /= E_Component
1029 or else not Is_Aliased (Comp)
1034 return not Comes_From_Source (Pref)
1035 and then In_Instance
1036 and then not Is_Constrained (Etype (Comp));
1037 end Is_Aliased_Unconstrained_Component;
1039 -- Start of processing for Apply_Discriminant_Check
1043 T_Typ := Designated_Type (Typ);
1048 -- Nothing to do if discriminant checks are suppressed or else no code
1049 -- is to be generated
1051 if not Expander_Active
1052 or else Discriminant_Checks_Suppressed (T_Typ)
1057 -- No discriminant checks necessary for an access when expression is
1058 -- statically Null. This is not only an optimization, it is fundamental
1059 -- because otherwise discriminant checks may be generated in init procs
1060 -- for types containing an access to a not-yet-frozen record, causing a
1061 -- deadly forward reference.
1063 -- Also, if the expression is of an access type whose designated type is
1064 -- incomplete, then the access value must be null and we suppress the
1067 if Known_Null (N) then
1070 elsif Is_Access_Type (S_Typ) then
1071 S_Typ := Designated_Type (S_Typ);
1073 if Ekind (S_Typ) = E_Incomplete_Type then
1078 -- If an assignment target is present, then we need to generate the
1079 -- actual subtype if the target is a parameter or aliased object with
1080 -- an unconstrained nominal subtype.
1082 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1083 -- subtype to the parameter and dereference cases, since other aliased
1084 -- objects are unconstrained (unless the nominal subtype is explicitly
1085 -- constrained). (But we also need to test for renamings???)
1088 and then (Present (Param_Entity (Lhs))
1089 or else (Ada_Version < Ada_05
1090 and then not Is_Constrained (T_Typ)
1091 and then Is_Aliased_View (Lhs)
1092 and then not Is_Aliased_Unconstrained_Component)
1093 or else (Ada_Version >= Ada_05
1094 and then not Is_Constrained (T_Typ)
1095 and then Nkind (Lhs) = N_Explicit_Dereference
1096 and then Nkind (Original_Node (Lhs)) /=
1099 T_Typ := Get_Actual_Subtype (Lhs);
1102 -- Nothing to do if the type is unconstrained (this is the case where
1103 -- the actual subtype in the RM sense of N is unconstrained and no check
1106 if not Is_Constrained (T_Typ) then
1109 -- Ada 2005: nothing to do if the type is one for which there is a
1110 -- partial view that is constrained.
1112 elsif Ada_Version >= Ada_05
1113 and then Has_Constrained_Partial_View (Base_Type (T_Typ))
1118 -- Nothing to do if the type is an Unchecked_Union
1120 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1124 -- Suppress checks if the subtypes are the same. the check must be
1125 -- preserved in an assignment to a formal, because the constraint is
1126 -- given by the actual.
1128 if Nkind (Original_Node (N)) /= N_Allocator
1130 or else not Is_Entity_Name (Lhs)
1131 or else No (Param_Entity (Lhs)))
1134 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1135 and then not Is_Aliased_View (Lhs)
1140 -- We can also eliminate checks on allocators with a subtype mark that
1141 -- coincides with the context type. The context type may be a subtype
1142 -- without a constraint (common case, a generic actual).
1144 elsif Nkind (Original_Node (N)) = N_Allocator
1145 and then Is_Entity_Name (Expression (Original_Node (N)))
1148 Alloc_Typ : constant Entity_Id :=
1149 Entity (Expression (Original_Node (N)));
1152 if Alloc_Typ = T_Typ
1153 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1154 and then Is_Entity_Name (
1155 Subtype_Indication (Parent (T_Typ)))
1156 and then Alloc_Typ = Base_Type (T_Typ))
1164 -- See if we have a case where the types are both constrained, and all
1165 -- the constraints are constants. In this case, we can do the check
1166 -- successfully at compile time.
1168 -- We skip this check for the case where the node is a rewritten`
1169 -- allocator, because it already carries the context subtype, and
1170 -- extracting the discriminants from the aggregate is messy.
1172 if Is_Constrained (S_Typ)
1173 and then Nkind (Original_Node (N)) /= N_Allocator
1183 -- S_Typ may not have discriminants in the case where it is a
1184 -- private type completed by a default discriminated type. In that
1185 -- case, we need to get the constraints from the underlying_type.
1186 -- If the underlying type is unconstrained (i.e. has no default
1187 -- discriminants) no check is needed.
1189 if Has_Discriminants (S_Typ) then
1190 Discr := First_Discriminant (S_Typ);
1191 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1194 Discr := First_Discriminant (Underlying_Type (S_Typ));
1197 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1203 -- A further optimization: if T_Typ is derived from S_Typ
1204 -- without imposing a constraint, no check is needed.
1206 if Nkind (Original_Node (Parent (T_Typ))) =
1207 N_Full_Type_Declaration
1210 Type_Def : constant Node_Id :=
1212 (Original_Node (Parent (T_Typ)));
1214 if Nkind (Type_Def) = N_Derived_Type_Definition
1215 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1216 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1224 DconT := First_Elmt (Discriminant_Constraint (T_Typ));
1226 while Present (Discr) loop
1227 ItemS := Node (DconS);
1228 ItemT := Node (DconT);
1230 -- For a discriminated component type constrained by the
1231 -- current instance of an enclosing type, there is no
1232 -- applicable discriminant check.
1234 if Nkind (ItemT) = N_Attribute_Reference
1235 and then Is_Access_Type (Etype (ItemT))
1236 and then Is_Entity_Name (Prefix (ItemT))
1237 and then Is_Type (Entity (Prefix (ItemT)))
1243 not Is_OK_Static_Expression (ItemS)
1245 not Is_OK_Static_Expression (ItemT);
1247 if Expr_Value (ItemS) /= Expr_Value (ItemT) then
1248 if Do_Access then -- needs run-time check.
1251 Apply_Compile_Time_Constraint_Error
1252 (N, "incorrect value for discriminant&?",
1253 CE_Discriminant_Check_Failed, Ent => Discr);
1260 Next_Discriminant (Discr);
1269 -- Here we need a discriminant check. First build the expression
1270 -- for the comparisons of the discriminants:
1272 -- (n.disc1 /= typ.disc1) or else
1273 -- (n.disc2 /= typ.disc2) or else
1275 -- (n.discn /= typ.discn)
1277 Cond := Build_Discriminant_Checks (N, T_Typ);
1279 -- If Lhs is set and is a parameter, then the condition is
1280 -- guarded by: lhs'constrained and then (condition built above)
1282 if Present (Param_Entity (Lhs)) then
1286 Make_Attribute_Reference (Loc,
1287 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1288 Attribute_Name => Name_Constrained),
1289 Right_Opnd => Cond);
1293 Cond := Guard_Access (Cond, Loc, N);
1297 Make_Raise_Constraint_Error (Loc,
1299 Reason => CE_Discriminant_Check_Failed));
1300 end Apply_Discriminant_Check;
1302 ------------------------
1303 -- Apply_Divide_Check --
1304 ------------------------
1306 procedure Apply_Divide_Check (N : Node_Id) is
1307 Loc : constant Source_Ptr := Sloc (N);
1308 Typ : constant Entity_Id := Etype (N);
1309 Left : constant Node_Id := Left_Opnd (N);
1310 Right : constant Node_Id := Right_Opnd (N);
1320 pragma Warnings (Off, Lhi);
1321 -- Don't actually use this value
1325 and then not Backend_Divide_Checks_On_Target
1326 and then Check_Needed (Right, Division_Check)
1328 Determine_Range (Right, ROK, Rlo, Rhi);
1330 -- See if division by zero possible, and if so generate test. This
1331 -- part of the test is not controlled by the -gnato switch.
1333 if Do_Division_Check (N) then
1334 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1336 Make_Raise_Constraint_Error (Loc,
1339 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1340 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1341 Reason => CE_Divide_By_Zero));
1345 -- Test for extremely annoying case of xxx'First divided by -1
1347 if Do_Overflow_Check (N) then
1348 if Nkind (N) = N_Op_Divide
1349 and then Is_Signed_Integer_Type (Typ)
1351 Determine_Range (Left, LOK, Llo, Lhi);
1352 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1354 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1356 ((not LOK) or else (Llo = LLB))
1359 Make_Raise_Constraint_Error (Loc,
1365 Duplicate_Subexpr_Move_Checks (Left),
1366 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1370 Duplicate_Subexpr (Right),
1372 Make_Integer_Literal (Loc, -1))),
1373 Reason => CE_Overflow_Check_Failed));
1378 end Apply_Divide_Check;
1380 ----------------------------------
1381 -- Apply_Float_Conversion_Check --
1382 ----------------------------------
1384 -- Let F and I be the source and target types of the conversion. The RM
1385 -- specifies that a floating-point value X is rounded to the nearest
1386 -- integer, with halfway cases being rounded away from zero. The rounded
1387 -- value of X is checked against I'Range.
1389 -- The catch in the above paragraph is that there is no good way to know
1390 -- whether the round-to-integer operation resulted in overflow. A remedy is
1391 -- to perform a range check in the floating-point domain instead, however:
1393 -- (1) The bounds may not be known at compile time
1394 -- (2) The check must take into account rounding or truncation.
1395 -- (3) The range of type I may not be exactly representable in F.
1396 -- (4) For the rounding case, The end-points I'First - 0.5 and
1397 -- I'Last + 0.5 may or may not be in range, depending on the
1398 -- sign of I'First and I'Last.
1399 -- (5) X may be a NaN, which will fail any comparison
1401 -- The following steps correctly convert X with rounding:
1403 -- (1) If either I'First or I'Last is not known at compile time, use
1404 -- I'Base instead of I in the next three steps and perform a
1405 -- regular range check against I'Range after conversion.
1406 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1407 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1408 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1409 -- In other words, take one of the closest floating-point numbers
1410 -- (which is an integer value) to I'First, and see if it is in
1412 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1413 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1414 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1415 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1416 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1418 -- For the truncating case, replace steps (2) and (3) as follows:
1419 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1420 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1422 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1423 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1426 procedure Apply_Float_Conversion_Check
1428 Target_Typ : Entity_Id)
1430 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1431 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1432 Loc : constant Source_Ptr := Sloc (Ck_Node);
1433 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1434 Target_Base : constant Entity_Id :=
1435 Implementation_Base_Type (Target_Typ);
1437 Par : constant Node_Id := Parent (Ck_Node);
1438 pragma Assert (Nkind (Par) = N_Type_Conversion);
1439 -- Parent of check node, must be a type conversion
1441 Truncate : constant Boolean := Float_Truncate (Par);
1442 Max_Bound : constant Uint :=
1444 (Machine_Radix (Expr_Type),
1445 Machine_Mantissa (Expr_Type) - 1) - 1;
1447 -- Largest bound, so bound plus or minus half is a machine number of F
1449 Ifirst, Ilast : Uint;
1450 -- Bounds of integer type
1453 -- Bounds to check in floating-point domain
1455 Lo_OK, Hi_OK : Boolean;
1456 -- True iff Lo resp. Hi belongs to I'Range
1458 Lo_Chk, Hi_Chk : Node_Id;
1459 -- Expressions that are False iff check fails
1461 Reason : RT_Exception_Code;
1464 if not Compile_Time_Known_Value (LB)
1465 or not Compile_Time_Known_Value (HB)
1468 -- First check that the value falls in the range of the base type,
1469 -- to prevent overflow during conversion and then perform a
1470 -- regular range check against the (dynamic) bounds.
1472 pragma Assert (Target_Base /= Target_Typ);
1474 Temp : constant Entity_Id :=
1475 Make_Defining_Identifier (Loc,
1476 Chars => New_Internal_Name ('T'));
1479 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1480 Set_Etype (Temp, Target_Base);
1482 Insert_Action (Parent (Par),
1483 Make_Object_Declaration (Loc,
1484 Defining_Identifier => Temp,
1485 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1486 Expression => New_Copy_Tree (Par)),
1487 Suppress => All_Checks);
1490 Make_Raise_Constraint_Error (Loc,
1493 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1494 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1495 Reason => CE_Range_Check_Failed));
1496 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
1502 -- Get the bounds of the target type
1504 Ifirst := Expr_Value (LB);
1505 Ilast := Expr_Value (HB);
1507 -- Check against lower bound
1509 if Truncate and then Ifirst > 0 then
1510 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
1514 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
1517 elsif abs (Ifirst) < Max_Bound then
1518 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
1519 Lo_OK := (Ifirst > 0);
1522 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
1523 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
1528 -- Lo_Chk := (X >= Lo)
1530 Lo_Chk := Make_Op_Ge (Loc,
1531 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1532 Right_Opnd => Make_Real_Literal (Loc, Lo));
1535 -- Lo_Chk := (X > Lo)
1537 Lo_Chk := Make_Op_Gt (Loc,
1538 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1539 Right_Opnd => Make_Real_Literal (Loc, Lo));
1542 -- Check against higher bound
1544 if Truncate and then Ilast < 0 then
1545 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
1549 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
1552 elsif abs (Ilast) < Max_Bound then
1553 Hi := UR_From_Uint (Ilast) + Ureal_Half;
1554 Hi_OK := (Ilast < 0);
1556 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
1557 Hi_OK := (Hi <= UR_From_Uint (Ilast));
1562 -- Hi_Chk := (X <= Hi)
1564 Hi_Chk := Make_Op_Le (Loc,
1565 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1566 Right_Opnd => Make_Real_Literal (Loc, Hi));
1569 -- Hi_Chk := (X < Hi)
1571 Hi_Chk := Make_Op_Lt (Loc,
1572 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1573 Right_Opnd => Make_Real_Literal (Loc, Hi));
1576 -- If the bounds of the target type are the same as those of the base
1577 -- type, the check is an overflow check as a range check is not
1578 -- performed in these cases.
1580 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
1581 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
1583 Reason := CE_Overflow_Check_Failed;
1585 Reason := CE_Range_Check_Failed;
1588 -- Raise CE if either conditions does not hold
1590 Insert_Action (Ck_Node,
1591 Make_Raise_Constraint_Error (Loc,
1592 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
1594 end Apply_Float_Conversion_Check;
1596 ------------------------
1597 -- Apply_Length_Check --
1598 ------------------------
1600 procedure Apply_Length_Check
1602 Target_Typ : Entity_Id;
1603 Source_Typ : Entity_Id := Empty)
1606 Apply_Selected_Length_Checks
1607 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1608 end Apply_Length_Check;
1610 -----------------------
1611 -- Apply_Range_Check --
1612 -----------------------
1614 procedure Apply_Range_Check
1616 Target_Typ : Entity_Id;
1617 Source_Typ : Entity_Id := Empty)
1620 Apply_Selected_Range_Checks
1621 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1622 end Apply_Range_Check;
1624 ------------------------------
1625 -- Apply_Scalar_Range_Check --
1626 ------------------------------
1628 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
1629 -- off if it is already set on.
1631 procedure Apply_Scalar_Range_Check
1633 Target_Typ : Entity_Id;
1634 Source_Typ : Entity_Id := Empty;
1635 Fixed_Int : Boolean := False)
1637 Parnt : constant Node_Id := Parent (Expr);
1639 Arr : Node_Id := Empty; -- initialize to prevent warning
1640 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
1643 Is_Subscr_Ref : Boolean;
1644 -- Set true if Expr is a subscript
1646 Is_Unconstrained_Subscr_Ref : Boolean;
1647 -- Set true if Expr is a subscript of an unconstrained array. In this
1648 -- case we do not attempt to do an analysis of the value against the
1649 -- range of the subscript, since we don't know the actual subtype.
1652 -- Set to True if Expr should be regarded as a real value even though
1653 -- the type of Expr might be discrete.
1655 procedure Bad_Value;
1656 -- Procedure called if value is determined to be out of range
1662 procedure Bad_Value is
1664 Apply_Compile_Time_Constraint_Error
1665 (Expr, "value not in range of}?", CE_Range_Check_Failed,
1670 -- Start of processing for Apply_Scalar_Range_Check
1673 -- Return if check obviously not needed
1676 -- Not needed inside generic
1680 -- Not needed if previous error
1682 or else Target_Typ = Any_Type
1683 or else Nkind (Expr) = N_Error
1685 -- Not needed for non-scalar type
1687 or else not Is_Scalar_Type (Target_Typ)
1689 -- Not needed if we know node raises CE already
1691 or else Raises_Constraint_Error (Expr)
1696 -- Now, see if checks are suppressed
1699 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
1701 if Is_Subscr_Ref then
1702 Arr := Prefix (Parnt);
1703 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
1706 if not Do_Range_Check (Expr) then
1708 -- Subscript reference. Check for Index_Checks suppressed
1710 if Is_Subscr_Ref then
1712 -- Check array type and its base type
1714 if Index_Checks_Suppressed (Arr_Typ)
1715 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
1719 -- Check array itself if it is an entity name
1721 elsif Is_Entity_Name (Arr)
1722 and then Index_Checks_Suppressed (Entity (Arr))
1726 -- Check expression itself if it is an entity name
1728 elsif Is_Entity_Name (Expr)
1729 and then Index_Checks_Suppressed (Entity (Expr))
1734 -- All other cases, check for Range_Checks suppressed
1737 -- Check target type and its base type
1739 if Range_Checks_Suppressed (Target_Typ)
1740 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
1744 -- Check expression itself if it is an entity name
1746 elsif Is_Entity_Name (Expr)
1747 and then Range_Checks_Suppressed (Entity (Expr))
1751 -- If Expr is part of an assignment statement, then check left
1752 -- side of assignment if it is an entity name.
1754 elsif Nkind (Parnt) = N_Assignment_Statement
1755 and then Is_Entity_Name (Name (Parnt))
1756 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
1763 -- Do not set range checks if they are killed
1765 if Nkind (Expr) = N_Unchecked_Type_Conversion
1766 and then Kill_Range_Check (Expr)
1771 -- Do not set range checks for any values from System.Scalar_Values
1772 -- since the whole idea of such values is to avoid checking them!
1774 if Is_Entity_Name (Expr)
1775 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
1780 -- Now see if we need a check
1782 if No (Source_Typ) then
1783 S_Typ := Etype (Expr);
1785 S_Typ := Source_Typ;
1788 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
1792 Is_Unconstrained_Subscr_Ref :=
1793 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
1795 -- Always do a range check if the source type includes infinities and
1796 -- the target type does not include infinities. We do not do this if
1797 -- range checks are killed.
1799 if Is_Floating_Point_Type (S_Typ)
1800 and then Has_Infinities (S_Typ)
1801 and then not Has_Infinities (Target_Typ)
1803 Enable_Range_Check (Expr);
1806 -- Return if we know expression is definitely in the range of the target
1807 -- type as determined by Determine_Range. Right now we only do this for
1808 -- discrete types, and not fixed-point or floating-point types.
1810 -- The additional less-precise tests below catch these cases
1812 -- Note: skip this if we are given a source_typ, since the point of
1813 -- supplying a Source_Typ is to stop us looking at the expression.
1814 -- We could sharpen this test to be out parameters only ???
1816 if Is_Discrete_Type (Target_Typ)
1817 and then Is_Discrete_Type (Etype (Expr))
1818 and then not Is_Unconstrained_Subscr_Ref
1819 and then No (Source_Typ)
1822 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
1823 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
1828 if Compile_Time_Known_Value (Tlo)
1829 and then Compile_Time_Known_Value (Thi)
1832 Lov : constant Uint := Expr_Value (Tlo);
1833 Hiv : constant Uint := Expr_Value (Thi);
1836 -- If range is null, we for sure have a constraint error
1837 -- (we don't even need to look at the value involved,
1838 -- since all possible values will raise CE).
1845 -- Otherwise determine range of value
1847 Determine_Range (Expr, OK, Lo, Hi);
1851 -- If definitely in range, all OK
1853 if Lo >= Lov and then Hi <= Hiv then
1856 -- If definitely not in range, warn
1858 elsif Lov > Hi or else Hiv < Lo then
1862 -- Otherwise we don't know
1874 Is_Floating_Point_Type (S_Typ)
1875 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
1877 -- Check if we can determine at compile time whether Expr is in the
1878 -- range of the target type. Note that if S_Typ is within the bounds
1879 -- of Target_Typ then this must be the case. This check is meaningful
1880 -- only if this is not a conversion between integer and real types.
1882 if not Is_Unconstrained_Subscr_Ref
1884 Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
1886 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
1888 Is_In_Range (Expr, Target_Typ, Fixed_Int, Int_Real))
1892 elsif Is_Out_Of_Range (Expr, Target_Typ, Fixed_Int, Int_Real) then
1896 -- In the floating-point case, we only do range checks if the type is
1897 -- constrained. We definitely do NOT want range checks for unconstrained
1898 -- types, since we want to have infinities
1900 elsif Is_Floating_Point_Type (S_Typ) then
1901 if Is_Constrained (S_Typ) then
1902 Enable_Range_Check (Expr);
1905 -- For all other cases we enable a range check unconditionally
1908 Enable_Range_Check (Expr);
1911 end Apply_Scalar_Range_Check;
1913 ----------------------------------
1914 -- Apply_Selected_Length_Checks --
1915 ----------------------------------
1917 procedure Apply_Selected_Length_Checks
1919 Target_Typ : Entity_Id;
1920 Source_Typ : Entity_Id;
1921 Do_Static : Boolean)
1924 R_Result : Check_Result;
1927 Loc : constant Source_Ptr := Sloc (Ck_Node);
1928 Checks_On : constant Boolean :=
1929 (not Index_Checks_Suppressed (Target_Typ))
1931 (not Length_Checks_Suppressed (Target_Typ));
1934 if not Expander_Active then
1939 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
1941 for J in 1 .. 2 loop
1942 R_Cno := R_Result (J);
1943 exit when No (R_Cno);
1945 -- A length check may mention an Itype which is attached to a
1946 -- subsequent node. At the top level in a package this can cause
1947 -- an order-of-elaboration problem, so we make sure that the itype
1948 -- is referenced now.
1950 if Ekind (Current_Scope) = E_Package
1951 and then Is_Compilation_Unit (Current_Scope)
1953 Ensure_Defined (Target_Typ, Ck_Node);
1955 if Present (Source_Typ) then
1956 Ensure_Defined (Source_Typ, Ck_Node);
1958 elsif Is_Itype (Etype (Ck_Node)) then
1959 Ensure_Defined (Etype (Ck_Node), Ck_Node);
1963 -- If the item is a conditional raise of constraint error, then have
1964 -- a look at what check is being performed and ???
1966 if Nkind (R_Cno) = N_Raise_Constraint_Error
1967 and then Present (Condition (R_Cno))
1969 Cond := Condition (R_Cno);
1971 -- Case where node does not now have a dynamic check
1973 if not Has_Dynamic_Length_Check (Ck_Node) then
1975 -- If checks are on, just insert the check
1978 Insert_Action (Ck_Node, R_Cno);
1980 if not Do_Static then
1981 Set_Has_Dynamic_Length_Check (Ck_Node);
1984 -- If checks are off, then analyze the length check after
1985 -- temporarily attaching it to the tree in case the relevant
1986 -- condition can be evaluted at compile time. We still want a
1987 -- compile time warning in this case.
1990 Set_Parent (R_Cno, Ck_Node);
1995 -- Output a warning if the condition is known to be True
1997 if Is_Entity_Name (Cond)
1998 and then Entity (Cond) = Standard_True
2000 Apply_Compile_Time_Constraint_Error
2001 (Ck_Node, "wrong length for array of}?",
2002 CE_Length_Check_Failed,
2006 -- If we were only doing a static check, or if checks are not
2007 -- on, then we want to delete the check, since it is not needed.
2008 -- We do this by replacing the if statement by a null statement
2010 elsif Do_Static or else not Checks_On then
2011 Remove_Warning_Messages (R_Cno);
2012 Rewrite (R_Cno, Make_Null_Statement (Loc));
2016 Install_Static_Check (R_Cno, Loc);
2019 end Apply_Selected_Length_Checks;
2021 ---------------------------------
2022 -- Apply_Selected_Range_Checks --
2023 ---------------------------------
2025 procedure Apply_Selected_Range_Checks
2027 Target_Typ : Entity_Id;
2028 Source_Typ : Entity_Id;
2029 Do_Static : Boolean)
2032 R_Result : Check_Result;
2035 Loc : constant Source_Ptr := Sloc (Ck_Node);
2036 Checks_On : constant Boolean :=
2037 (not Index_Checks_Suppressed (Target_Typ))
2039 (not Range_Checks_Suppressed (Target_Typ));
2042 if not Expander_Active or else not Checks_On then
2047 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2049 for J in 1 .. 2 loop
2051 R_Cno := R_Result (J);
2052 exit when No (R_Cno);
2054 -- If the item is a conditional raise of constraint error, then have
2055 -- a look at what check is being performed and ???
2057 if Nkind (R_Cno) = N_Raise_Constraint_Error
2058 and then Present (Condition (R_Cno))
2060 Cond := Condition (R_Cno);
2062 if not Has_Dynamic_Range_Check (Ck_Node) then
2063 Insert_Action (Ck_Node, R_Cno);
2065 if not Do_Static then
2066 Set_Has_Dynamic_Range_Check (Ck_Node);
2070 -- Output a warning if the condition is known to be True
2072 if Is_Entity_Name (Cond)
2073 and then Entity (Cond) = Standard_True
2075 -- Since an N_Range is technically not an expression, we have
2076 -- to set one of the bounds to C_E and then just flag the
2077 -- N_Range. The warning message will point to the lower bound
2078 -- and complain about a range, which seems OK.
2080 if Nkind (Ck_Node) = N_Range then
2081 Apply_Compile_Time_Constraint_Error
2082 (Low_Bound (Ck_Node), "static range out of bounds of}?",
2083 CE_Range_Check_Failed,
2087 Set_Raises_Constraint_Error (Ck_Node);
2090 Apply_Compile_Time_Constraint_Error
2091 (Ck_Node, "static value out of range of}?",
2092 CE_Range_Check_Failed,
2097 -- If we were only doing a static check, or if checks are not
2098 -- on, then we want to delete the check, since it is not needed.
2099 -- We do this by replacing the if statement by a null statement
2101 elsif Do_Static or else not Checks_On then
2102 Remove_Warning_Messages (R_Cno);
2103 Rewrite (R_Cno, Make_Null_Statement (Loc));
2107 Install_Static_Check (R_Cno, Loc);
2110 end Apply_Selected_Range_Checks;
2112 -------------------------------
2113 -- Apply_Static_Length_Check --
2114 -------------------------------
2116 procedure Apply_Static_Length_Check
2118 Target_Typ : Entity_Id;
2119 Source_Typ : Entity_Id := Empty)
2122 Apply_Selected_Length_Checks
2123 (Expr, Target_Typ, Source_Typ, Do_Static => True);
2124 end Apply_Static_Length_Check;
2126 -------------------------------------
2127 -- Apply_Subscript_Validity_Checks --
2128 -------------------------------------
2130 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
2134 pragma Assert (Nkind (Expr) = N_Indexed_Component);
2136 -- Loop through subscripts
2138 Sub := First (Expressions (Expr));
2139 while Present (Sub) loop
2141 -- Check one subscript. Note that we do not worry about enumeration
2142 -- type with holes, since we will convert the value to a Pos value
2143 -- for the subscript, and that convert will do the necessary validity
2146 Ensure_Valid (Sub, Holes_OK => True);
2148 -- Move to next subscript
2152 end Apply_Subscript_Validity_Checks;
2154 ----------------------------------
2155 -- Apply_Type_Conversion_Checks --
2156 ----------------------------------
2158 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
2159 Target_Type : constant Entity_Id := Etype (N);
2160 Target_Base : constant Entity_Id := Base_Type (Target_Type);
2161 Expr : constant Node_Id := Expression (N);
2162 Expr_Type : constant Entity_Id := Etype (Expr);
2165 if Inside_A_Generic then
2168 -- Skip these checks if serious errors detected, there are some nasty
2169 -- situations of incomplete trees that blow things up.
2171 elsif Serious_Errors_Detected > 0 then
2174 -- Scalar type conversions of the form Target_Type (Expr) require a
2175 -- range check if we cannot be sure that Expr is in the base type of
2176 -- Target_Typ and also that Expr is in the range of Target_Typ. These
2177 -- are not quite the same condition from an implementation point of
2178 -- view, but clearly the second includes the first.
2180 elsif Is_Scalar_Type (Target_Type) then
2182 Conv_OK : constant Boolean := Conversion_OK (N);
2183 -- If the Conversion_OK flag on the type conversion is set and no
2184 -- floating point type is involved in the type conversion then
2185 -- fixed point values must be read as integral values.
2187 Float_To_Int : constant Boolean :=
2188 Is_Floating_Point_Type (Expr_Type)
2189 and then Is_Integer_Type (Target_Type);
2192 if not Overflow_Checks_Suppressed (Target_Base)
2193 and then not In_Subrange_Of (Expr_Type, Target_Base, Conv_OK)
2194 and then not Float_To_Int
2196 Activate_Overflow_Check (N);
2199 if not Range_Checks_Suppressed (Target_Type)
2200 and then not Range_Checks_Suppressed (Expr_Type)
2202 if Float_To_Int then
2203 Apply_Float_Conversion_Check (Expr, Target_Type);
2205 Apply_Scalar_Range_Check
2206 (Expr, Target_Type, Fixed_Int => Conv_OK);
2211 elsif Comes_From_Source (N)
2212 and then Is_Record_Type (Target_Type)
2213 and then Is_Derived_Type (Target_Type)
2214 and then not Is_Tagged_Type (Target_Type)
2215 and then not Is_Constrained (Target_Type)
2216 and then Present (Stored_Constraint (Target_Type))
2218 -- An unconstrained derived type may have inherited discriminant
2219 -- Build an actual discriminant constraint list using the stored
2220 -- constraint, to verify that the expression of the parent type
2221 -- satisfies the constraints imposed by the (unconstrained!)
2222 -- derived type. This applies to value conversions, not to view
2223 -- conversions of tagged types.
2226 Loc : constant Source_Ptr := Sloc (N);
2228 Constraint : Elmt_Id;
2229 Discr_Value : Node_Id;
2232 New_Constraints : constant Elist_Id := New_Elmt_List;
2233 Old_Constraints : constant Elist_Id :=
2234 Discriminant_Constraint (Expr_Type);
2237 Constraint := First_Elmt (Stored_Constraint (Target_Type));
2238 while Present (Constraint) loop
2239 Discr_Value := Node (Constraint);
2241 if Is_Entity_Name (Discr_Value)
2242 and then Ekind (Entity (Discr_Value)) = E_Discriminant
2244 Discr := Corresponding_Discriminant (Entity (Discr_Value));
2247 and then Scope (Discr) = Base_Type (Expr_Type)
2249 -- Parent is constrained by new discriminant. Obtain
2250 -- Value of original discriminant in expression. If the
2251 -- new discriminant has been used to constrain more than
2252 -- one of the stored discriminants, this will provide the
2253 -- required consistency check.
2256 Make_Selected_Component (Loc,
2258 Duplicate_Subexpr_No_Checks
2259 (Expr, Name_Req => True),
2261 Make_Identifier (Loc, Chars (Discr))),
2265 -- Discriminant of more remote ancestor ???
2270 -- Derived type definition has an explicit value for this
2271 -- stored discriminant.
2275 (Duplicate_Subexpr_No_Checks (Discr_Value),
2279 Next_Elmt (Constraint);
2282 -- Use the unconstrained expression type to retrieve the
2283 -- discriminants of the parent, and apply momentarily the
2284 -- discriminant constraint synthesized above.
2286 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
2287 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
2288 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
2291 Make_Raise_Constraint_Error (Loc,
2293 Reason => CE_Discriminant_Check_Failed));
2296 -- For arrays, conversions are applied during expansion, to take into
2297 -- accounts changes of representation. The checks become range checks on
2298 -- the base type or length checks on the subtype, depending on whether
2299 -- the target type is unconstrained or constrained.
2304 end Apply_Type_Conversion_Checks;
2306 ----------------------------------------------
2307 -- Apply_Universal_Integer_Attribute_Checks --
2308 ----------------------------------------------
2310 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
2311 Loc : constant Source_Ptr := Sloc (N);
2312 Typ : constant Entity_Id := Etype (N);
2315 if Inside_A_Generic then
2318 -- Nothing to do if checks are suppressed
2320 elsif Range_Checks_Suppressed (Typ)
2321 and then Overflow_Checks_Suppressed (Typ)
2325 -- Nothing to do if the attribute does not come from source. The
2326 -- internal attributes we generate of this type do not need checks,
2327 -- and furthermore the attempt to check them causes some circular
2328 -- elaboration orders when dealing with packed types.
2330 elsif not Comes_From_Source (N) then
2333 -- If the prefix is a selected component that depends on a discriminant
2334 -- the check may improperly expose a discriminant instead of using
2335 -- the bounds of the object itself. Set the type of the attribute to
2336 -- the base type of the context, so that a check will be imposed when
2337 -- needed (e.g. if the node appears as an index).
2339 elsif Nkind (Prefix (N)) = N_Selected_Component
2340 and then Ekind (Typ) = E_Signed_Integer_Subtype
2341 and then Depends_On_Discriminant (Scalar_Range (Typ))
2343 Set_Etype (N, Base_Type (Typ));
2345 -- Otherwise, replace the attribute node with a type conversion node
2346 -- whose expression is the attribute, retyped to universal integer, and
2347 -- whose subtype mark is the target type. The call to analyze this
2348 -- conversion will set range and overflow checks as required for proper
2349 -- detection of an out of range value.
2352 Set_Etype (N, Universal_Integer);
2353 Set_Analyzed (N, True);
2356 Make_Type_Conversion (Loc,
2357 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
2358 Expression => Relocate_Node (N)));
2360 Analyze_And_Resolve (N, Typ);
2363 end Apply_Universal_Integer_Attribute_Checks;
2365 -------------------------------
2366 -- Build_Discriminant_Checks --
2367 -------------------------------
2369 function Build_Discriminant_Checks
2371 T_Typ : Entity_Id) return Node_Id
2373 Loc : constant Source_Ptr := Sloc (N);
2376 Disc_Ent : Entity_Id;
2380 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
2382 ----------------------------------
2383 -- Aggregate_Discriminant_Value --
2384 ----------------------------------
2386 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
2390 -- The aggregate has been normalized with named associations. We use
2391 -- the Chars field to locate the discriminant to take into account
2392 -- discriminants in derived types, which carry the same name as those
2395 Assoc := First (Component_Associations (N));
2396 while Present (Assoc) loop
2397 if Chars (First (Choices (Assoc))) = Chars (Disc) then
2398 return Expression (Assoc);
2404 -- Discriminant must have been found in the loop above
2406 raise Program_Error;
2407 end Aggregate_Discriminant_Val;
2409 -- Start of processing for Build_Discriminant_Checks
2412 -- Loop through discriminants evolving the condition
2415 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
2417 -- For a fully private type, use the discriminants of the parent type
2419 if Is_Private_Type (T_Typ)
2420 and then No (Full_View (T_Typ))
2422 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
2424 Disc_Ent := First_Discriminant (T_Typ);
2427 while Present (Disc) loop
2428 Dval := Node (Disc);
2430 if Nkind (Dval) = N_Identifier
2431 and then Ekind (Entity (Dval)) = E_Discriminant
2433 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
2435 Dval := Duplicate_Subexpr_No_Checks (Dval);
2438 -- If we have an Unchecked_Union node, we can infer the discriminants
2441 if Is_Unchecked_Union (Base_Type (T_Typ)) then
2443 Get_Discriminant_Value (
2444 First_Discriminant (T_Typ),
2446 Stored_Constraint (T_Typ)));
2448 elsif Nkind (N) = N_Aggregate then
2450 Duplicate_Subexpr_No_Checks
2451 (Aggregate_Discriminant_Val (Disc_Ent));
2455 Make_Selected_Component (Loc,
2457 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
2459 Make_Identifier (Loc, Chars (Disc_Ent)));
2461 Set_Is_In_Discriminant_Check (Dref);
2464 Evolve_Or_Else (Cond,
2467 Right_Opnd => Dval));
2470 Next_Discriminant (Disc_Ent);
2474 end Build_Discriminant_Checks;
2480 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
2488 -- Always check if not simple entity
2490 if Nkind (Nod) not in N_Has_Entity
2491 or else not Comes_From_Source (Nod)
2496 -- Look up tree for short circuit
2503 -- Done if out of subexpression (note that we allow generated stuff
2504 -- such as itype declarations in this context, to keep the loop going
2505 -- since we may well have generated such stuff in complex situations.
2506 -- Also done if no parent (probably an error condition, but no point
2507 -- in behaving nasty if we find it!)
2510 or else (K not in N_Subexpr and then Comes_From_Source (P))
2514 -- Or/Or Else case, where test is part of the right operand, or is
2515 -- part of one of the actions associated with the right operand, and
2516 -- the left operand is an equality test.
2518 elsif K = N_Op_Or then
2519 exit when N = Right_Opnd (P)
2520 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2522 elsif K = N_Or_Else then
2523 exit when (N = Right_Opnd (P)
2526 and then List_Containing (N) = Actions (P)))
2527 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2529 -- Similar test for the And/And then case, where the left operand
2530 -- is an inequality test.
2532 elsif K = N_Op_And then
2533 exit when N = Right_Opnd (P)
2534 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2536 elsif K = N_And_Then then
2537 exit when (N = Right_Opnd (P)
2540 and then List_Containing (N) = Actions (P)))
2541 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2547 -- If we fall through the loop, then we have a conditional with an
2548 -- appropriate test as its left operand. So test further.
2551 R := Right_Opnd (L);
2554 -- Left operand of test must match original variable
2556 if Nkind (L) not in N_Has_Entity
2557 or else Entity (L) /= Entity (Nod)
2562 -- Right operand of test must be key value (zero or null)
2565 when Access_Check =>
2566 if not Known_Null (R) then
2570 when Division_Check =>
2571 if not Compile_Time_Known_Value (R)
2572 or else Expr_Value (R) /= Uint_0
2578 raise Program_Error;
2581 -- Here we have the optimizable case, warn if not short-circuited
2583 if K = N_Op_And or else K = N_Op_Or then
2585 when Access_Check =>
2587 ("Constraint_Error may be raised (access check)?",
2589 when Division_Check =>
2591 ("Constraint_Error may be raised (zero divide)?",
2595 raise Program_Error;
2598 if K = N_Op_And then
2599 Error_Msg_N ("use `AND THEN` instead of AND?", P);
2601 Error_Msg_N ("use `OR ELSE` instead of OR?", P);
2604 -- If not short-circuited, we need the ckeck
2608 -- If short-circuited, we can omit the check
2615 -----------------------------------
2616 -- Check_Valid_Lvalue_Subscripts --
2617 -----------------------------------
2619 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
2621 -- Skip this if range checks are suppressed
2623 if Range_Checks_Suppressed (Etype (Expr)) then
2626 -- Only do this check for expressions that come from source. We assume
2627 -- that expander generated assignments explicitly include any necessary
2628 -- checks. Note that this is not just an optimization, it avoids
2629 -- infinite recursions!
2631 elsif not Comes_From_Source (Expr) then
2634 -- For a selected component, check the prefix
2636 elsif Nkind (Expr) = N_Selected_Component then
2637 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2640 -- Case of indexed component
2642 elsif Nkind (Expr) = N_Indexed_Component then
2643 Apply_Subscript_Validity_Checks (Expr);
2645 -- Prefix may itself be or contain an indexed component, and these
2646 -- subscripts need checking as well.
2648 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2650 end Check_Valid_Lvalue_Subscripts;
2652 ----------------------------------
2653 -- Null_Exclusion_Static_Checks --
2654 ----------------------------------
2656 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
2657 Error_Node : Node_Id;
2659 Has_Null : constant Boolean := Has_Null_Exclusion (N);
2660 K : constant Node_Kind := Nkind (N);
2665 (K = N_Component_Declaration
2666 or else K = N_Discriminant_Specification
2667 or else K = N_Function_Specification
2668 or else K = N_Object_Declaration
2669 or else K = N_Parameter_Specification);
2671 if K = N_Function_Specification then
2672 Typ := Etype (Defining_Entity (N));
2674 Typ := Etype (Defining_Identifier (N));
2678 when N_Component_Declaration =>
2679 if Present (Access_Definition (Component_Definition (N))) then
2680 Error_Node := Component_Definition (N);
2682 Error_Node := Subtype_Indication (Component_Definition (N));
2685 when N_Discriminant_Specification =>
2686 Error_Node := Discriminant_Type (N);
2688 when N_Function_Specification =>
2689 Error_Node := Result_Definition (N);
2691 when N_Object_Declaration =>
2692 Error_Node := Object_Definition (N);
2694 when N_Parameter_Specification =>
2695 Error_Node := Parameter_Type (N);
2698 raise Program_Error;
2703 -- Enforce legality rule 3.10 (13): A null exclusion can only be
2704 -- applied to an access [sub]type.
2706 if not Is_Access_Type (Typ) then
2708 ("`NOT NULL` allowed only for an access type", Error_Node);
2710 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
2711 -- be applied to a [sub]type that does not exclude null already.
2713 elsif Can_Never_Be_Null (Typ)
2715 -- No need to check itypes that have a null exclusion because
2716 -- they are already examined at their point of creation.
2718 and then not Is_Itype (Typ)
2721 ("`NOT NULL` not allowed (& already excludes null)",
2726 -- Check that null-excluding objects are always initialized
2728 if K = N_Object_Declaration
2729 and then No (Expression (N))
2730 and then not No_Initialization (N)
2732 -- Add an expression that assigns null. This node is needed by
2733 -- Apply_Compile_Time_Constraint_Error, which will replace this with
2734 -- a Constraint_Error node.
2736 Set_Expression (N, Make_Null (Sloc (N)));
2737 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
2739 Apply_Compile_Time_Constraint_Error
2740 (N => Expression (N),
2741 Msg => "(Ada 2005) null-excluding objects must be initialized?",
2742 Reason => CE_Null_Not_Allowed);
2745 -- Check that a null-excluding component, formal or object is not
2746 -- being assigned a null value. Otherwise generate a warning message
2747 -- and replace Expression (N) by a N_Constraint_Error node.
2749 if K /= N_Function_Specification then
2750 Expr := Expression (N);
2752 if Present (Expr) and then Known_Null (Expr) then
2754 when N_Component_Declaration |
2755 N_Discriminant_Specification =>
2756 Apply_Compile_Time_Constraint_Error
2758 Msg => "(Ada 2005) null not allowed " &
2759 "in null-excluding components?",
2760 Reason => CE_Null_Not_Allowed);
2762 when N_Object_Declaration =>
2763 Apply_Compile_Time_Constraint_Error
2765 Msg => "(Ada 2005) null not allowed " &
2766 "in null-excluding objects?",
2767 Reason => CE_Null_Not_Allowed);
2769 when N_Parameter_Specification =>
2770 Apply_Compile_Time_Constraint_Error
2772 Msg => "(Ada 2005) null not allowed " &
2773 "in null-excluding formals?",
2774 Reason => CE_Null_Not_Allowed);
2781 end Null_Exclusion_Static_Checks;
2783 ----------------------------------
2784 -- Conditional_Statements_Begin --
2785 ----------------------------------
2787 procedure Conditional_Statements_Begin is
2789 Saved_Checks_TOS := Saved_Checks_TOS + 1;
2791 -- If stack overflows, kill all checks, that way we know to simply reset
2792 -- the number of saved checks to zero on return. This should never occur
2795 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2798 -- In the normal case, we just make a new stack entry saving the current
2799 -- number of saved checks for a later restore.
2802 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
2804 if Debug_Flag_CC then
2805 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
2809 end Conditional_Statements_Begin;
2811 --------------------------------
2812 -- Conditional_Statements_End --
2813 --------------------------------
2815 procedure Conditional_Statements_End is
2817 pragma Assert (Saved_Checks_TOS > 0);
2819 -- If the saved checks stack overflowed, then we killed all checks, so
2820 -- setting the number of saved checks back to zero is correct. This
2821 -- should never occur in practice.
2823 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2824 Num_Saved_Checks := 0;
2826 -- In the normal case, restore the number of saved checks from the top
2830 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
2831 if Debug_Flag_CC then
2832 w ("Conditional_Statements_End: Num_Saved_Checks = ",
2837 Saved_Checks_TOS := Saved_Checks_TOS - 1;
2838 end Conditional_Statements_End;
2840 ---------------------
2841 -- Determine_Range --
2842 ---------------------
2844 Cache_Size : constant := 2 ** 10;
2845 type Cache_Index is range 0 .. Cache_Size - 1;
2846 -- Determine size of below cache (power of 2 is more efficient!)
2848 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
2849 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
2850 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
2851 -- The above arrays are used to implement a small direct cache for
2852 -- Determine_Range calls. Because of the way Determine_Range recursively
2853 -- traces subexpressions, and because overflow checking calls the routine
2854 -- on the way up the tree, a quadratic behavior can otherwise be
2855 -- encountered in large expressions. The cache entry for node N is stored
2856 -- in the (N mod Cache_Size) entry, and can be validated by checking the
2857 -- actual node value stored there.
2859 procedure Determine_Range
2865 Typ : constant Entity_Id := Etype (N);
2869 -- Lo and Hi bounds of left operand
2873 -- Lo and Hi bounds of right (or only) operand
2876 -- Temp variable used to hold a bound node
2879 -- High bound of base type of expression
2883 -- Refined values for low and high bounds, after tightening
2886 -- Used in lower level calls to indicate if call succeeded
2888 Cindex : Cache_Index;
2889 -- Used to search cache
2891 function OK_Operands return Boolean;
2892 -- Used for binary operators. Determines the ranges of the left and
2893 -- right operands, and if they are both OK, returns True, and puts
2894 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left
2900 function OK_Operands return Boolean is
2902 Determine_Range (Left_Opnd (N), OK1, Lo_Left, Hi_Left);
2908 Determine_Range (Right_Opnd (N), OK1, Lo_Right, Hi_Right);
2912 -- Start of processing for Determine_Range
2915 -- Prevent junk warnings by initializing range variables
2922 -- If the type is not discrete, or is undefined, then we can't do
2923 -- anything about determining the range.
2925 if No (Typ) or else not Is_Discrete_Type (Typ)
2926 or else Error_Posted (N)
2932 -- For all other cases, we can determine the range
2936 -- If value is compile time known, then the possible range is the one
2937 -- value that we know this expression definitely has!
2939 if Compile_Time_Known_Value (N) then
2940 Lo := Expr_Value (N);
2945 -- Return if already in the cache
2947 Cindex := Cache_Index (N mod Cache_Size);
2949 if Determine_Range_Cache_N (Cindex) = N then
2950 Lo := Determine_Range_Cache_Lo (Cindex);
2951 Hi := Determine_Range_Cache_Hi (Cindex);
2955 -- Otherwise, start by finding the bounds of the type of the expression,
2956 -- the value cannot be outside this range (if it is, then we have an
2957 -- overflow situation, which is a separate check, we are talking here
2958 -- only about the expression value).
2960 -- We use the actual bound unless it is dynamic, in which case use the
2961 -- corresponding base type bound if possible. If we can't get a bound
2962 -- then we figure we can't determine the range (a peculiar case, that
2963 -- perhaps cannot happen, but there is no point in bombing in this
2964 -- optimization circuit.
2966 -- First the low bound
2968 Bound := Type_Low_Bound (Typ);
2970 if Compile_Time_Known_Value (Bound) then
2971 Lo := Expr_Value (Bound);
2973 elsif Compile_Time_Known_Value (Type_Low_Bound (Base_Type (Typ))) then
2974 Lo := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
2981 -- Now the high bound
2983 Bound := Type_High_Bound (Typ);
2985 -- We need the high bound of the base type later on, and this should
2986 -- always be compile time known. Again, it is not clear that this
2987 -- can ever be false, but no point in bombing.
2989 if Compile_Time_Known_Value (Type_High_Bound (Base_Type (Typ))) then
2990 Hbound := Expr_Value (Type_High_Bound (Base_Type (Typ)));
2998 -- If we have a static subtype, then that may have a tighter bound so
2999 -- use the upper bound of the subtype instead in this case.
3001 if Compile_Time_Known_Value (Bound) then
3002 Hi := Expr_Value (Bound);
3005 -- We may be able to refine this value in certain situations. If any
3006 -- refinement is possible, then Lor and Hir are set to possibly tighter
3007 -- bounds, and OK1 is set to True.
3011 -- For unary plus, result is limited by range of operand
3014 Determine_Range (Right_Opnd (N), OK1, Lor, Hir);
3016 -- For unary minus, determine range of operand, and negate it
3019 Determine_Range (Right_Opnd (N), OK1, Lo_Right, Hi_Right);
3026 -- For binary addition, get range of each operand and do the
3027 -- addition to get the result range.
3031 Lor := Lo_Left + Lo_Right;
3032 Hir := Hi_Left + Hi_Right;
3035 -- Division is tricky. The only case we consider is where the right
3036 -- operand is a positive constant, and in this case we simply divide
3037 -- the bounds of the left operand
3041 if Lo_Right = Hi_Right
3042 and then Lo_Right > 0
3044 Lor := Lo_Left / Lo_Right;
3045 Hir := Hi_Left / Lo_Right;
3052 -- For binary subtraction, get range of each operand and do the worst
3053 -- case subtraction to get the result range.
3055 when N_Op_Subtract =>
3057 Lor := Lo_Left - Hi_Right;
3058 Hir := Hi_Left - Lo_Right;
3061 -- For MOD, if right operand is a positive constant, then result must
3062 -- be in the allowable range of mod results.
3066 if Lo_Right = Hi_Right
3067 and then Lo_Right /= 0
3069 if Lo_Right > 0 then
3071 Hir := Lo_Right - 1;
3073 else -- Lo_Right < 0
3074 Lor := Lo_Right + 1;
3083 -- For REM, if right operand is a positive constant, then result must
3084 -- be in the allowable range of mod results.
3088 if Lo_Right = Hi_Right
3089 and then Lo_Right /= 0
3092 Dval : constant Uint := (abs Lo_Right) - 1;
3095 -- The sign of the result depends on the sign of the
3096 -- dividend (but not on the sign of the divisor, hence
3097 -- the abs operation above).
3117 -- Attribute reference cases
3119 when N_Attribute_Reference =>
3120 case Attribute_Name (N) is
3122 -- For Pos/Val attributes, we can refine the range using the
3123 -- possible range of values of the attribute expression
3125 when Name_Pos | Name_Val =>
3126 Determine_Range (First (Expressions (N)), OK1, Lor, Hir);
3128 -- For Length attribute, use the bounds of the corresponding
3129 -- index type to refine the range.
3133 Atyp : Entity_Id := Etype (Prefix (N));
3141 if Is_Access_Type (Atyp) then
3142 Atyp := Designated_Type (Atyp);
3145 -- For string literal, we know exact value
3147 if Ekind (Atyp) = E_String_Literal_Subtype then
3149 Lo := String_Literal_Length (Atyp);
3150 Hi := String_Literal_Length (Atyp);
3154 -- Otherwise check for expression given
3156 if No (Expressions (N)) then
3160 UI_To_Int (Expr_Value (First (Expressions (N))));
3163 Indx := First_Index (Atyp);
3164 for J in 2 .. Inum loop
3165 Indx := Next_Index (Indx);
3169 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU);
3173 (Type_High_Bound (Etype (Indx)), OK1, UL, UU);
3177 -- The maximum value for Length is the biggest
3178 -- possible gap between the values of the bounds.
3179 -- But of course, this value cannot be negative.
3181 Hir := UI_Max (Uint_0, UU - LL);
3183 -- For constrained arrays, the minimum value for
3184 -- Length is taken from the actual value of the
3185 -- bounds, since the index will be exactly of
3188 if Is_Constrained (Atyp) then
3189 Lor := UI_Max (Uint_0, UL - LU);
3191 -- For an unconstrained array, the minimum value
3192 -- for length is always zero.
3201 -- No special handling for other attributes
3202 -- Probably more opportunities exist here ???
3209 -- For type conversion from one discrete type to another, we can
3210 -- refine the range using the converted value.
3212 when N_Type_Conversion =>
3213 Determine_Range (Expression (N), OK1, Lor, Hir);
3215 -- Nothing special to do for all other expression kinds
3223 -- At this stage, if OK1 is true, then we know that the actual
3224 -- result of the computed expression is in the range Lor .. Hir.
3225 -- We can use this to restrict the possible range of results.
3229 -- If the refined value of the low bound is greater than the
3230 -- type high bound, then reset it to the more restrictive
3231 -- value. However, we do NOT do this for the case of a modular
3232 -- type where the possible upper bound on the value is above the
3233 -- base type high bound, because that means the result could wrap.
3236 and then not (Is_Modular_Integer_Type (Typ)
3237 and then Hir > Hbound)
3242 -- Similarly, if the refined value of the high bound is less
3243 -- than the value so far, then reset it to the more restrictive
3244 -- value. Again, we do not do this if the refined low bound is
3245 -- negative for a modular type, since this would wrap.
3248 and then not (Is_Modular_Integer_Type (Typ)
3249 and then Lor < Uint_0)
3255 -- Set cache entry for future call and we are all done
3257 Determine_Range_Cache_N (Cindex) := N;
3258 Determine_Range_Cache_Lo (Cindex) := Lo;
3259 Determine_Range_Cache_Hi (Cindex) := Hi;
3262 -- If any exception occurs, it means that we have some bug in the compiler
3263 -- possibly triggered by a previous error, or by some unforseen peculiar
3264 -- occurrence. However, this is only an optimization attempt, so there is
3265 -- really no point in crashing the compiler. Instead we just decide, too
3266 -- bad, we can't figure out a range in this case after all.
3271 -- Debug flag K disables this behavior (useful for debugging)
3273 if Debug_Flag_K then
3281 end Determine_Range;
3283 ------------------------------------
3284 -- Discriminant_Checks_Suppressed --
3285 ------------------------------------
3287 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
3290 if Is_Unchecked_Union (E) then
3292 elsif Checks_May_Be_Suppressed (E) then
3293 return Is_Check_Suppressed (E, Discriminant_Check);
3297 return Scope_Suppress (Discriminant_Check);
3298 end Discriminant_Checks_Suppressed;
3300 --------------------------------
3301 -- Division_Checks_Suppressed --
3302 --------------------------------
3304 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
3306 if Present (E) and then Checks_May_Be_Suppressed (E) then
3307 return Is_Check_Suppressed (E, Division_Check);
3309 return Scope_Suppress (Division_Check);
3311 end Division_Checks_Suppressed;
3313 -----------------------------------
3314 -- Elaboration_Checks_Suppressed --
3315 -----------------------------------
3317 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
3319 -- The complication in this routine is that if we are in the dynamic
3320 -- model of elaboration, we also check All_Checks, since All_Checks
3321 -- does not set Elaboration_Check explicitly.
3324 if Kill_Elaboration_Checks (E) then
3327 elsif Checks_May_Be_Suppressed (E) then
3328 if Is_Check_Suppressed (E, Elaboration_Check) then
3330 elsif Dynamic_Elaboration_Checks then
3331 return Is_Check_Suppressed (E, All_Checks);
3338 if Scope_Suppress (Elaboration_Check) then
3340 elsif Dynamic_Elaboration_Checks then
3341 return Scope_Suppress (All_Checks);
3345 end Elaboration_Checks_Suppressed;
3347 ---------------------------
3348 -- Enable_Overflow_Check --
3349 ---------------------------
3351 procedure Enable_Overflow_Check (N : Node_Id) is
3352 Typ : constant Entity_Id := Base_Type (Etype (N));
3361 if Debug_Flag_CC then
3362 w ("Enable_Overflow_Check for node ", Int (N));
3363 Write_Str (" Source location = ");
3368 -- Nothing to do if the range of the result is known OK. We skip this
3369 -- for conversions, since the caller already did the check, and in any
3370 -- case the condition for deleting the check for a type conversion is
3371 -- different in any case.
3373 if Nkind (N) /= N_Type_Conversion then
3374 Determine_Range (N, OK, Lo, Hi);
3376 -- Note in the test below that we assume that if a bound of the
3377 -- range is equal to that of the type. That's not quite accurate
3378 -- but we do this for the following reasons:
3380 -- a) The way that Determine_Range works, it will typically report
3381 -- the bounds of the value as being equal to the bounds of the
3382 -- type, because it either can't tell anything more precise, or
3383 -- does not think it is worth the effort to be more precise.
3385 -- b) It is very unusual to have a situation in which this would
3386 -- generate an unnecessary overflow check (an example would be
3387 -- a subtype with a range 0 .. Integer'Last - 1 to which the
3388 -- literal value one is added.
3390 -- c) The alternative is a lot of special casing in this routine
3391 -- which would partially duplicate Determine_Range processing.
3394 and then Lo > Expr_Value (Type_Low_Bound (Typ))
3395 and then Hi < Expr_Value (Type_High_Bound (Typ))
3397 if Debug_Flag_CC then
3398 w ("No overflow check required");
3405 -- If not in optimizing mode, set flag and we are done. We are also done
3406 -- (and just set the flag) if the type is not a discrete type, since it
3407 -- is not worth the effort to eliminate checks for other than discrete
3408 -- types. In addition, we take this same path if we have stored the
3409 -- maximum number of checks possible already (a very unlikely situation,
3410 -- but we do not want to blow up!)
3412 if Optimization_Level = 0
3413 or else not Is_Discrete_Type (Etype (N))
3414 or else Num_Saved_Checks = Saved_Checks'Last
3416 Activate_Overflow_Check (N);
3418 if Debug_Flag_CC then
3419 w ("Optimization off");
3425 -- Otherwise evaluate and check the expression
3430 Target_Type => Empty,
3436 if Debug_Flag_CC then
3437 w ("Called Find_Check");
3441 w (" Check_Num = ", Chk);
3442 w (" Ent = ", Int (Ent));
3443 Write_Str (" Ofs = ");
3448 -- If check is not of form to optimize, then set flag and we are done
3451 Activate_Overflow_Check (N);
3455 -- If check is already performed, then return without setting flag
3458 if Debug_Flag_CC then
3459 w ("Check suppressed!");
3465 -- Here we will make a new entry for the new check
3467 Activate_Overflow_Check (N);
3468 Num_Saved_Checks := Num_Saved_Checks + 1;
3469 Saved_Checks (Num_Saved_Checks) :=
3474 Target_Type => Empty);
3476 if Debug_Flag_CC then
3477 w ("Make new entry, check number = ", Num_Saved_Checks);
3478 w (" Entity = ", Int (Ent));
3479 Write_Str (" Offset = ");
3481 w (" Check_Type = O");
3482 w (" Target_Type = Empty");
3485 -- If we get an exception, then something went wrong, probably because of
3486 -- an error in the structure of the tree due to an incorrect program. Or it
3487 -- may be a bug in the optimization circuit. In either case the safest
3488 -- thing is simply to set the check flag unconditionally.
3492 Activate_Overflow_Check (N);
3494 if Debug_Flag_CC then
3495 w (" exception occurred, overflow flag set");
3499 end Enable_Overflow_Check;
3501 ------------------------
3502 -- Enable_Range_Check --
3503 ------------------------
3505 procedure Enable_Range_Check (N : Node_Id) is
3514 -- Return if unchecked type conversion with range check killed. In this
3515 -- case we never set the flag (that's what Kill_Range_Check is about!)
3517 if Nkind (N) = N_Unchecked_Type_Conversion
3518 and then Kill_Range_Check (N)
3523 -- Check for various cases where we should suppress the range check
3525 -- No check if range checks suppressed for type of node
3527 if Present (Etype (N))
3528 and then Range_Checks_Suppressed (Etype (N))
3532 -- No check if node is an entity name, and range checks are suppressed
3533 -- for this entity, or for the type of this entity.
3535 elsif Is_Entity_Name (N)
3536 and then (Range_Checks_Suppressed (Entity (N))
3537 or else Range_Checks_Suppressed (Etype (Entity (N))))
3541 -- No checks if index of array, and index checks are suppressed for
3542 -- the array object or the type of the array.
3544 elsif Nkind (Parent (N)) = N_Indexed_Component then
3546 Pref : constant Node_Id := Prefix (Parent (N));
3548 if Is_Entity_Name (Pref)
3549 and then Index_Checks_Suppressed (Entity (Pref))
3552 elsif Index_Checks_Suppressed (Etype (Pref)) then
3558 -- Debug trace output
3560 if Debug_Flag_CC then
3561 w ("Enable_Range_Check for node ", Int (N));
3562 Write_Str (" Source location = ");
3567 -- If not in optimizing mode, set flag and we are done. We are also done
3568 -- (and just set the flag) if the type is not a discrete type, since it
3569 -- is not worth the effort to eliminate checks for other than discrete
3570 -- types. In addition, we take this same path if we have stored the
3571 -- maximum number of checks possible already (a very unlikely situation,
3572 -- but we do not want to blow up!)
3574 if Optimization_Level = 0
3575 or else No (Etype (N))
3576 or else not Is_Discrete_Type (Etype (N))
3577 or else Num_Saved_Checks = Saved_Checks'Last
3579 Activate_Range_Check (N);
3581 if Debug_Flag_CC then
3582 w ("Optimization off");
3588 -- Otherwise find out the target type
3592 -- For assignment, use left side subtype
3594 if Nkind (P) = N_Assignment_Statement
3595 and then Expression (P) = N
3597 Ttyp := Etype (Name (P));
3599 -- For indexed component, use subscript subtype
3601 elsif Nkind (P) = N_Indexed_Component then
3608 Atyp := Etype (Prefix (P));
3610 if Is_Access_Type (Atyp) then
3611 Atyp := Designated_Type (Atyp);
3613 -- If the prefix is an access to an unconstrained array,
3614 -- perform check unconditionally: it depends on the bounds of
3615 -- an object and we cannot currently recognize whether the test
3616 -- may be redundant.
3618 if not Is_Constrained (Atyp) then
3619 Activate_Range_Check (N);
3623 -- Ditto if the prefix is an explicit dereference whose designated
3624 -- type is unconstrained.
3626 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
3627 and then not Is_Constrained (Atyp)
3629 Activate_Range_Check (N);
3633 Indx := First_Index (Atyp);
3634 Subs := First (Expressions (P));
3637 Ttyp := Etype (Indx);
3646 -- For now, ignore all other cases, they are not so interesting
3649 if Debug_Flag_CC then
3650 w (" target type not found, flag set");
3653 Activate_Range_Check (N);
3657 -- Evaluate and check the expression
3662 Target_Type => Ttyp,
3668 if Debug_Flag_CC then
3669 w ("Called Find_Check");
3670 w ("Target_Typ = ", Int (Ttyp));
3674 w (" Check_Num = ", Chk);
3675 w (" Ent = ", Int (Ent));
3676 Write_Str (" Ofs = ");
3681 -- If check is not of form to optimize, then set flag and we are done
3684 if Debug_Flag_CC then
3685 w (" expression not of optimizable type, flag set");
3688 Activate_Range_Check (N);
3692 -- If check is already performed, then return without setting flag
3695 if Debug_Flag_CC then
3696 w ("Check suppressed!");
3702 -- Here we will make a new entry for the new check
3704 Activate_Range_Check (N);
3705 Num_Saved_Checks := Num_Saved_Checks + 1;
3706 Saved_Checks (Num_Saved_Checks) :=
3711 Target_Type => Ttyp);
3713 if Debug_Flag_CC then
3714 w ("Make new entry, check number = ", Num_Saved_Checks);
3715 w (" Entity = ", Int (Ent));
3716 Write_Str (" Offset = ");
3718 w (" Check_Type = R");
3719 w (" Target_Type = ", Int (Ttyp));
3720 pg (Union_Id (Ttyp));
3723 -- If we get an exception, then something went wrong, probably because of
3724 -- an error in the structure of the tree due to an incorrect program. Or
3725 -- it may be a bug in the optimization circuit. In either case the safest
3726 -- thing is simply to set the check flag unconditionally.
3730 Activate_Range_Check (N);
3732 if Debug_Flag_CC then
3733 w (" exception occurred, range flag set");
3737 end Enable_Range_Check;
3743 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
3744 Typ : constant Entity_Id := Etype (Expr);
3747 -- Ignore call if we are not doing any validity checking
3749 if not Validity_Checks_On then
3752 -- Ignore call if range or validity checks suppressed on entity or type
3754 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
3757 -- No check required if expression is from the expander, we assume the
3758 -- expander will generate whatever checks are needed. Note that this is
3759 -- not just an optimization, it avoids infinite recursions!
3761 -- Unchecked conversions must be checked, unless they are initialized
3762 -- scalar values, as in a component assignment in an init proc.
3764 -- In addition, we force a check if Force_Validity_Checks is set
3766 elsif not Comes_From_Source (Expr)
3767 and then not Force_Validity_Checks
3768 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
3769 or else Kill_Range_Check (Expr))
3773 -- No check required if expression is known to have valid value
3775 elsif Expr_Known_Valid (Expr) then
3778 -- Ignore case of enumeration with holes where the flag is set not to
3779 -- worry about holes, since no special validity check is needed
3781 elsif Is_Enumeration_Type (Typ)
3782 and then Has_Non_Standard_Rep (Typ)
3787 -- No check required on the left-hand side of an assignment
3789 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
3790 and then Expr = Name (Parent (Expr))
3794 -- No check on a univeral real constant. The context will eventually
3795 -- convert it to a machine number for some target type, or report an
3798 elsif Nkind (Expr) = N_Real_Literal
3799 and then Etype (Expr) = Universal_Real
3803 -- If the expression denotes a component of a packed boolean arrray,
3804 -- no possible check applies. We ignore the old ACATS chestnuts that
3805 -- involve Boolean range True..True.
3807 -- Note: validity checks are generated for expressions that yield a
3808 -- scalar type, when it is possible to create a value that is outside of
3809 -- the type. If this is a one-bit boolean no such value exists. This is
3810 -- an optimization, and it also prevents compiler blowing up during the
3811 -- elaboration of improperly expanded packed array references.
3813 elsif Nkind (Expr) = N_Indexed_Component
3814 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
3815 and then Root_Type (Etype (Expr)) = Standard_Boolean
3819 -- An annoying special case. If this is an out parameter of a scalar
3820 -- type, then the value is not going to be accessed, therefore it is
3821 -- inappropriate to do any validity check at the call site.
3824 -- Only need to worry about scalar types
3826 if Is_Scalar_Type (Typ) then
3836 -- Find actual argument (which may be a parameter association)
3837 -- and the parent of the actual argument (the call statement)
3842 if Nkind (P) = N_Parameter_Association then
3847 -- Only need to worry if we are argument of a procedure call
3848 -- since functions don't have out parameters. If this is an
3849 -- indirect or dispatching call, get signature from the
3852 if Nkind (P) = N_Procedure_Call_Statement then
3853 L := Parameter_Associations (P);
3855 if Is_Entity_Name (Name (P)) then
3856 E := Entity (Name (P));
3858 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
3859 E := Etype (Name (P));
3862 -- Only need to worry if there are indeed actuals, and if
3863 -- this could be a procedure call, otherwise we cannot get a
3864 -- match (either we are not an argument, or the mode of the
3865 -- formal is not OUT). This test also filters out the
3868 if Is_Non_Empty_List (L)
3869 and then Is_Subprogram (E)
3871 -- This is the loop through parameters, looking for an
3872 -- OUT parameter for which we are the argument.
3874 F := First_Formal (E);
3876 while Present (F) loop
3877 if Ekind (F) = E_Out_Parameter and then A = N then
3890 -- If we fall through, a validity check is required
3892 Insert_Valid_Check (Expr);
3894 if Is_Entity_Name (Expr)
3895 and then Safe_To_Capture_Value (Expr, Entity (Expr))
3897 Set_Is_Known_Valid (Entity (Expr));
3901 ----------------------
3902 -- Expr_Known_Valid --
3903 ----------------------
3905 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
3906 Typ : constant Entity_Id := Etype (Expr);
3909 -- Non-scalar types are always considered valid, since they never give
3910 -- rise to the issues of erroneous or bounded error behavior that are
3911 -- the concern. In formal reference manual terms the notion of validity
3912 -- only applies to scalar types. Note that even when packed arrays are
3913 -- represented using modular types, they are still arrays semantically,
3914 -- so they are also always valid (in particular, the unused bits can be
3915 -- random rubbish without affecting the validity of the array value).
3917 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
3920 -- If no validity checking, then everything is considered valid
3922 elsif not Validity_Checks_On then
3925 -- Floating-point types are considered valid unless floating-point
3926 -- validity checks have been specifically turned on.
3928 elsif Is_Floating_Point_Type (Typ)
3929 and then not Validity_Check_Floating_Point
3933 -- If the expression is the value of an object that is known to be
3934 -- valid, then clearly the expression value itself is valid.
3936 elsif Is_Entity_Name (Expr)
3937 and then Is_Known_Valid (Entity (Expr))
3941 -- References to discriminants are always considered valid. The value
3942 -- of a discriminant gets checked when the object is built. Within the
3943 -- record, we consider it valid, and it is important to do so, since
3944 -- otherwise we can try to generate bogus validity checks which
3945 -- reference discriminants out of scope. Discriminants of concurrent
3946 -- types are excluded for the same reason.
3948 elsif Is_Entity_Name (Expr)
3949 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
3953 -- If the type is one for which all values are known valid, then we are
3954 -- sure that the value is valid except in the slightly odd case where
3955 -- the expression is a reference to a variable whose size has been
3956 -- explicitly set to a value greater than the object size.
3958 elsif Is_Known_Valid (Typ) then
3959 if Is_Entity_Name (Expr)
3960 and then Ekind (Entity (Expr)) = E_Variable
3961 and then Esize (Entity (Expr)) > Esize (Typ)
3968 -- Integer and character literals always have valid values, where
3969 -- appropriate these will be range checked in any case.
3971 elsif Nkind (Expr) = N_Integer_Literal
3973 Nkind (Expr) = N_Character_Literal
3977 -- If we have a type conversion or a qualification of a known valid
3978 -- value, then the result will always be valid.
3980 elsif Nkind (Expr) = N_Type_Conversion
3982 Nkind (Expr) = N_Qualified_Expression
3984 return Expr_Known_Valid (Expression (Expr));
3986 -- The result of any operator is always considered valid, since we
3987 -- assume the necessary checks are done by the operator. For operators
3988 -- on floating-point operations, we must also check when the operation
3989 -- is the right-hand side of an assignment, or is an actual in a call.
3991 elsif Nkind (Expr) in N_Op then
3992 if Is_Floating_Point_Type (Typ)
3993 and then Validity_Check_Floating_Point
3995 (Nkind (Parent (Expr)) = N_Assignment_Statement
3996 or else Nkind (Parent (Expr)) = N_Function_Call
3997 or else Nkind (Parent (Expr)) = N_Parameter_Association)
4004 -- The result of a membership test is always valid, since it is true or
4005 -- false, there are no other possibilities.
4007 elsif Nkind (Expr) in N_Membership_Test then
4010 -- For all other cases, we do not know the expression is valid
4015 end Expr_Known_Valid;
4021 procedure Find_Check
4023 Check_Type : Character;
4024 Target_Type : Entity_Id;
4025 Entry_OK : out Boolean;
4026 Check_Num : out Nat;
4027 Ent : out Entity_Id;
4030 function Within_Range_Of
4031 (Target_Type : Entity_Id;
4032 Check_Type : Entity_Id) return Boolean;
4033 -- Given a requirement for checking a range against Target_Type, and
4034 -- and a range Check_Type against which a check has already been made,
4035 -- determines if the check against check type is sufficient to ensure
4036 -- that no check against Target_Type is required.
4038 ---------------------
4039 -- Within_Range_Of --
4040 ---------------------
4042 function Within_Range_Of
4043 (Target_Type : Entity_Id;
4044 Check_Type : Entity_Id) return Boolean
4047 if Target_Type = Check_Type then
4052 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
4053 Thi : constant Node_Id := Type_High_Bound (Target_Type);
4054 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
4055 Chi : constant Node_Id := Type_High_Bound (Check_Type);
4059 or else (Compile_Time_Known_Value (Tlo)
4061 Compile_Time_Known_Value (Clo)
4063 Expr_Value (Clo) >= Expr_Value (Tlo)))
4066 or else (Compile_Time_Known_Value (Thi)
4068 Compile_Time_Known_Value (Chi)
4070 Expr_Value (Chi) <= Expr_Value (Clo)))
4078 end Within_Range_Of;
4080 -- Start of processing for Find_Check
4083 -- Establish default, to avoid warnings from GCC
4087 -- Case of expression is simple entity reference
4089 if Is_Entity_Name (Expr) then
4090 Ent := Entity (Expr);
4093 -- Case of expression is entity + known constant
4095 elsif Nkind (Expr) = N_Op_Add
4096 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4097 and then Is_Entity_Name (Left_Opnd (Expr))
4099 Ent := Entity (Left_Opnd (Expr));
4100 Ofs := Expr_Value (Right_Opnd (Expr));
4102 -- Case of expression is entity - known constant
4104 elsif Nkind (Expr) = N_Op_Subtract
4105 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4106 and then Is_Entity_Name (Left_Opnd (Expr))
4108 Ent := Entity (Left_Opnd (Expr));
4109 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
4111 -- Any other expression is not of the right form
4120 -- Come here with expression of appropriate form, check if entity is an
4121 -- appropriate one for our purposes.
4123 if (Ekind (Ent) = E_Variable
4125 Ekind (Ent) = E_Constant
4127 Ekind (Ent) = E_Loop_Parameter
4129 Ekind (Ent) = E_In_Parameter)
4130 and then not Is_Library_Level_Entity (Ent)
4138 -- See if there is matching check already
4140 for J in reverse 1 .. Num_Saved_Checks loop
4142 SC : Saved_Check renames Saved_Checks (J);
4145 if SC.Killed = False
4146 and then SC.Entity = Ent
4147 and then SC.Offset = Ofs
4148 and then SC.Check_Type = Check_Type
4149 and then Within_Range_Of (Target_Type, SC.Target_Type)
4157 -- If we fall through entry was not found
4163 ---------------------------------
4164 -- Generate_Discriminant_Check --
4165 ---------------------------------
4167 -- Note: the code for this procedure is derived from the
4168 -- Emit_Discriminant_Check Routine in trans.c.
4170 procedure Generate_Discriminant_Check (N : Node_Id) is
4171 Loc : constant Source_Ptr := Sloc (N);
4172 Pref : constant Node_Id := Prefix (N);
4173 Sel : constant Node_Id := Selector_Name (N);
4175 Orig_Comp : constant Entity_Id :=
4176 Original_Record_Component (Entity (Sel));
4177 -- The original component to be checked
4179 Discr_Fct : constant Entity_Id :=
4180 Discriminant_Checking_Func (Orig_Comp);
4181 -- The discriminant checking function
4184 -- One discriminant to be checked in the type
4186 Real_Discr : Entity_Id;
4187 -- Actual discriminant in the call
4189 Pref_Type : Entity_Id;
4190 -- Type of relevant prefix (ignoring private/access stuff)
4193 -- List of arguments for function call
4196 -- Keep track of the formal corresponding to the actual we build for
4197 -- each discriminant, in order to be able to perform the necessary type
4201 -- Selected component reference for checking function argument
4204 Pref_Type := Etype (Pref);
4206 -- Force evaluation of the prefix, so that it does not get evaluated
4207 -- twice (once for the check, once for the actual reference). Such a
4208 -- double evaluation is always a potential source of inefficiency,
4209 -- and is functionally incorrect in the volatile case, or when the
4210 -- prefix may have side-effects. An entity or a component of an
4211 -- entity requires no evaluation.
4213 if Is_Entity_Name (Pref) then
4214 if Treat_As_Volatile (Entity (Pref)) then
4215 Force_Evaluation (Pref, Name_Req => True);
4218 elsif Treat_As_Volatile (Etype (Pref)) then
4219 Force_Evaluation (Pref, Name_Req => True);
4221 elsif Nkind (Pref) = N_Selected_Component
4222 and then Is_Entity_Name (Prefix (Pref))
4227 Force_Evaluation (Pref, Name_Req => True);
4230 -- For a tagged type, use the scope of the original component to
4231 -- obtain the type, because ???
4233 if Is_Tagged_Type (Scope (Orig_Comp)) then
4234 Pref_Type := Scope (Orig_Comp);
4236 -- For an untagged derived type, use the discriminants of the parent
4237 -- which have been renamed in the derivation, possibly by a one-to-many
4238 -- discriminant constraint. For non-tagged type, initially get the Etype
4242 if Is_Derived_Type (Pref_Type)
4243 and then Number_Discriminants (Pref_Type) /=
4244 Number_Discriminants (Etype (Base_Type (Pref_Type)))
4246 Pref_Type := Etype (Base_Type (Pref_Type));
4250 -- We definitely should have a checking function, This routine should
4251 -- not be called if no discriminant checking function is present.
4253 pragma Assert (Present (Discr_Fct));
4255 -- Create the list of the actual parameters for the call. This list
4256 -- is the list of the discriminant fields of the record expression to
4257 -- be discriminant checked.
4260 Formal := First_Formal (Discr_Fct);
4261 Discr := First_Discriminant (Pref_Type);
4262 while Present (Discr) loop
4264 -- If we have a corresponding discriminant field, and a parent
4265 -- subtype is present, then we want to use the corresponding
4266 -- discriminant since this is the one with the useful value.
4268 if Present (Corresponding_Discriminant (Discr))
4269 and then Ekind (Pref_Type) = E_Record_Type
4270 and then Present (Parent_Subtype (Pref_Type))
4272 Real_Discr := Corresponding_Discriminant (Discr);
4274 Real_Discr := Discr;
4277 -- Construct the reference to the discriminant
4280 Make_Selected_Component (Loc,
4282 Unchecked_Convert_To (Pref_Type,
4283 Duplicate_Subexpr (Pref)),
4284 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
4286 -- Manually analyze and resolve this selected component. We really
4287 -- want it just as it appears above, and do not want the expander
4288 -- playing discriminal games etc with this reference. Then we append
4289 -- the argument to the list we are gathering.
4291 Set_Etype (Scomp, Etype (Real_Discr));
4292 Set_Analyzed (Scomp, True);
4293 Append_To (Args, Convert_To (Etype (Formal), Scomp));
4295 Next_Formal_With_Extras (Formal);
4296 Next_Discriminant (Discr);
4299 -- Now build and insert the call
4302 Make_Raise_Constraint_Error (Loc,
4304 Make_Function_Call (Loc,
4305 Name => New_Occurrence_Of (Discr_Fct, Loc),
4306 Parameter_Associations => Args),
4307 Reason => CE_Discriminant_Check_Failed));
4308 end Generate_Discriminant_Check;
4310 ---------------------------
4311 -- Generate_Index_Checks --
4312 ---------------------------
4314 procedure Generate_Index_Checks (N : Node_Id) is
4315 Loc : constant Source_Ptr := Sloc (N);
4316 A : constant Node_Id := Prefix (N);
4322 -- Ignore call if index checks suppressed for array object or type
4324 if (Is_Entity_Name (A) and then Index_Checks_Suppressed (Entity (A)))
4325 or else Index_Checks_Suppressed (Etype (A))
4330 -- Generate the checks
4332 Sub := First (Expressions (N));
4334 while Present (Sub) loop
4335 if Do_Range_Check (Sub) then
4336 Set_Do_Range_Check (Sub, False);
4338 -- Force evaluation except for the case of a simple name of a
4339 -- non-volatile entity.
4341 if not Is_Entity_Name (Sub)
4342 or else Treat_As_Volatile (Entity (Sub))
4344 Force_Evaluation (Sub);
4347 -- Generate a raise of constraint error with the appropriate
4348 -- reason and a condition of the form:
4350 -- Base_Type(Sub) not in array'range (subscript)
4352 -- Note that the reason we generate the conversion to the base
4353 -- type here is that we definitely want the range check to take
4354 -- place, even if it looks like the subtype is OK. Optimization
4355 -- considerations that allow us to omit the check have already
4356 -- been taken into account in the setting of the Do_Range_Check
4362 Num := New_List (Make_Integer_Literal (Loc, Ind));
4366 Make_Raise_Constraint_Error (Loc,
4370 Convert_To (Base_Type (Etype (Sub)),
4371 Duplicate_Subexpr_Move_Checks (Sub)),
4373 Make_Attribute_Reference (Loc,
4374 Prefix => Duplicate_Subexpr_Move_Checks (A),
4375 Attribute_Name => Name_Range,
4376 Expressions => Num)),
4377 Reason => CE_Index_Check_Failed));
4383 end Generate_Index_Checks;
4385 --------------------------
4386 -- Generate_Range_Check --
4387 --------------------------
4389 procedure Generate_Range_Check
4391 Target_Type : Entity_Id;
4392 Reason : RT_Exception_Code)
4394 Loc : constant Source_Ptr := Sloc (N);
4395 Source_Type : constant Entity_Id := Etype (N);
4396 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
4397 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
4400 -- First special case, if the source type is already within the range
4401 -- of the target type, then no check is needed (probably we should have
4402 -- stopped Do_Range_Check from being set in the first place, but better
4403 -- late than later in preventing junk code!
4405 -- We do NOT apply this if the source node is a literal, since in this
4406 -- case the literal has already been labeled as having the subtype of
4409 if In_Subrange_Of (Source_Type, Target_Type)
4411 (Nkind (N) = N_Integer_Literal
4413 Nkind (N) = N_Real_Literal
4415 Nkind (N) = N_Character_Literal
4418 and then Ekind (Entity (N)) = E_Enumeration_Literal))
4423 -- We need a check, so force evaluation of the node, so that it does
4424 -- not get evaluated twice (once for the check, once for the actual
4425 -- reference). Such a double evaluation is always a potential source
4426 -- of inefficiency, and is functionally incorrect in the volatile case.
4428 if not Is_Entity_Name (N)
4429 or else Treat_As_Volatile (Entity (N))
4431 Force_Evaluation (N);
4434 -- The easiest case is when Source_Base_Type and Target_Base_Type are
4435 -- the same since in this case we can simply do a direct check of the
4436 -- value of N against the bounds of Target_Type.
4438 -- [constraint_error when N not in Target_Type]
4440 -- Note: this is by far the most common case, for example all cases of
4441 -- checks on the RHS of assignments are in this category, but not all
4442 -- cases are like this. Notably conversions can involve two types.
4444 if Source_Base_Type = Target_Base_Type then
4446 Make_Raise_Constraint_Error (Loc,
4449 Left_Opnd => Duplicate_Subexpr (N),
4450 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4453 -- Next test for the case where the target type is within the bounds
4454 -- of the base type of the source type, since in this case we can
4455 -- simply convert these bounds to the base type of T to do the test.
4457 -- [constraint_error when N not in
4458 -- Source_Base_Type (Target_Type'First)
4460 -- Source_Base_Type(Target_Type'Last))]
4462 -- The conversions will always work and need no check
4464 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
4466 Make_Raise_Constraint_Error (Loc,
4469 Left_Opnd => Duplicate_Subexpr (N),
4474 Convert_To (Source_Base_Type,
4475 Make_Attribute_Reference (Loc,
4477 New_Occurrence_Of (Target_Type, Loc),
4478 Attribute_Name => Name_First)),
4481 Convert_To (Source_Base_Type,
4482 Make_Attribute_Reference (Loc,
4484 New_Occurrence_Of (Target_Type, Loc),
4485 Attribute_Name => Name_Last)))),
4488 -- Note that at this stage we now that the Target_Base_Type is not in
4489 -- the range of the Source_Base_Type (since even the Target_Type itself
4490 -- is not in this range). It could still be the case that Source_Type is
4491 -- in range of the target base type since we have not checked that case.
4493 -- If that is the case, we can freely convert the source to the target,
4494 -- and then test the target result against the bounds.
4496 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
4498 -- We make a temporary to hold the value of the converted value
4499 -- (converted to the base type), and then we will do the test against
4502 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
4503 -- [constraint_error when Tnn not in Target_Type]
4505 -- Then the conversion itself is replaced by an occurrence of Tnn
4508 Tnn : constant Entity_Id :=
4509 Make_Defining_Identifier (Loc,
4510 Chars => New_Internal_Name ('T'));
4513 Insert_Actions (N, New_List (
4514 Make_Object_Declaration (Loc,
4515 Defining_Identifier => Tnn,
4516 Object_Definition =>
4517 New_Occurrence_Of (Target_Base_Type, Loc),
4518 Constant_Present => True,
4520 Make_Type_Conversion (Loc,
4521 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
4522 Expression => Duplicate_Subexpr (N))),
4524 Make_Raise_Constraint_Error (Loc,
4527 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4528 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4530 Reason => Reason)));
4532 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4534 -- Set the type of N, because the declaration for Tnn might not
4535 -- be analyzed yet, as is the case if N appears within a record
4536 -- declaration, as a discriminant constraint or expression.
4538 Set_Etype (N, Target_Base_Type);
4541 -- At this stage, we know that we have two scalar types, which are
4542 -- directly convertible, and where neither scalar type has a base
4543 -- range that is in the range of the other scalar type.
4545 -- The only way this can happen is with a signed and unsigned type.
4546 -- So test for these two cases:
4549 -- Case of the source is unsigned and the target is signed
4551 if Is_Unsigned_Type (Source_Base_Type)
4552 and then not Is_Unsigned_Type (Target_Base_Type)
4554 -- If the source is unsigned and the target is signed, then we
4555 -- know that the source is not shorter than the target (otherwise
4556 -- the source base type would be in the target base type range).
4558 -- In other words, the unsigned type is either the same size as
4559 -- the target, or it is larger. It cannot be smaller.
4562 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
4564 -- We only need to check the low bound if the low bound of the
4565 -- target type is non-negative. If the low bound of the target
4566 -- type is negative, then we know that we will fit fine.
4568 -- If the high bound of the target type is negative, then we
4569 -- know we have a constraint error, since we can't possibly
4570 -- have a negative source.
4572 -- With these two checks out of the way, we can do the check
4573 -- using the source type safely
4575 -- This is definitely the most annoying case!
4577 -- [constraint_error
4578 -- when (Target_Type'First >= 0
4580 -- N < Source_Base_Type (Target_Type'First))
4581 -- or else Target_Type'Last < 0
4582 -- or else N > Source_Base_Type (Target_Type'Last)];
4584 -- We turn off all checks since we know that the conversions
4585 -- will work fine, given the guards for negative values.
4588 Make_Raise_Constraint_Error (Loc,
4594 Left_Opnd => Make_Op_Ge (Loc,
4596 Make_Attribute_Reference (Loc,
4598 New_Occurrence_Of (Target_Type, Loc),
4599 Attribute_Name => Name_First),
4600 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4604 Left_Opnd => Duplicate_Subexpr (N),
4606 Convert_To (Source_Base_Type,
4607 Make_Attribute_Reference (Loc,
4609 New_Occurrence_Of (Target_Type, Loc),
4610 Attribute_Name => Name_First)))),
4615 Make_Attribute_Reference (Loc,
4616 Prefix => New_Occurrence_Of (Target_Type, Loc),
4617 Attribute_Name => Name_Last),
4618 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
4622 Left_Opnd => Duplicate_Subexpr (N),
4624 Convert_To (Source_Base_Type,
4625 Make_Attribute_Reference (Loc,
4626 Prefix => New_Occurrence_Of (Target_Type, Loc),
4627 Attribute_Name => Name_Last)))),
4630 Suppress => All_Checks);
4632 -- Only remaining possibility is that the source is signed and
4633 -- the target is unsigned
4636 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
4637 and then Is_Unsigned_Type (Target_Base_Type));
4639 -- If the source is signed and the target is unsigned, then we
4640 -- know that the target is not shorter than the source (otherwise
4641 -- the target base type would be in the source base type range).
4643 -- In other words, the unsigned type is either the same size as
4644 -- the target, or it is larger. It cannot be smaller.
4646 -- Clearly we have an error if the source value is negative since
4647 -- no unsigned type can have negative values. If the source type
4648 -- is non-negative, then the check can be done using the target
4651 -- Tnn : constant Target_Base_Type (N) := Target_Type;
4653 -- [constraint_error
4654 -- when N < 0 or else Tnn not in Target_Type];
4656 -- We turn off all checks for the conversion of N to the target
4657 -- base type, since we generate the explicit check to ensure that
4658 -- the value is non-negative
4661 Tnn : constant Entity_Id :=
4662 Make_Defining_Identifier (Loc,
4663 Chars => New_Internal_Name ('T'));
4666 Insert_Actions (N, New_List (
4667 Make_Object_Declaration (Loc,
4668 Defining_Identifier => Tnn,
4669 Object_Definition =>
4670 New_Occurrence_Of (Target_Base_Type, Loc),
4671 Constant_Present => True,
4673 Make_Type_Conversion (Loc,
4675 New_Occurrence_Of (Target_Base_Type, Loc),
4676 Expression => Duplicate_Subexpr (N))),
4678 Make_Raise_Constraint_Error (Loc,
4683 Left_Opnd => Duplicate_Subexpr (N),
4684 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4688 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4690 New_Occurrence_Of (Target_Type, Loc))),
4693 Suppress => All_Checks);
4695 -- Set the Etype explicitly, because Insert_Actions may have
4696 -- placed the declaration in the freeze list for an enclosing
4697 -- construct, and thus it is not analyzed yet.
4699 Set_Etype (Tnn, Target_Base_Type);
4700 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4704 end Generate_Range_Check;
4710 function Get_Check_Id (N : Name_Id) return Check_Id is
4712 -- For standard check name, we can do a direct computation
4714 if N in First_Check_Name .. Last_Check_Name then
4715 return Check_Id (N - (First_Check_Name - 1));
4717 -- For non-standard names added by pragma Check_Name, search table
4720 for J in All_Checks + 1 .. Check_Names.Last loop
4721 if Check_Names.Table (J) = N then
4727 -- No matching name found
4732 ---------------------
4733 -- Get_Discriminal --
4734 ---------------------
4736 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
4737 Loc : constant Source_Ptr := Sloc (E);
4742 -- The bound can be a bona fide parameter of a protected operation,
4743 -- rather than a prival encoded as an in-parameter.
4745 if No (Discriminal_Link (Entity (Bound))) then
4749 -- Climb the scope stack looking for an enclosing protected type. If
4750 -- we run out of scopes, return the bound itself.
4753 while Present (Sc) loop
4754 if Sc = Standard_Standard then
4757 elsif Ekind (Sc) = E_Protected_Type then
4764 D := First_Discriminant (Sc);
4765 while Present (D) loop
4766 if Chars (D) = Chars (Bound) then
4767 return New_Occurrence_Of (Discriminal (D), Loc);
4770 Next_Discriminant (D);
4774 end Get_Discriminal;
4776 ----------------------
4777 -- Get_Range_Checks --
4778 ----------------------
4780 function Get_Range_Checks
4782 Target_Typ : Entity_Id;
4783 Source_Typ : Entity_Id := Empty;
4784 Warn_Node : Node_Id := Empty) return Check_Result
4787 return Selected_Range_Checks
4788 (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
4789 end Get_Range_Checks;
4795 function Guard_Access
4798 Ck_Node : Node_Id) return Node_Id
4801 if Nkind (Cond) = N_Or_Else then
4802 Set_Paren_Count (Cond, 1);
4805 if Nkind (Ck_Node) = N_Allocator then
4812 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
4813 Right_Opnd => Make_Null (Loc)),
4814 Right_Opnd => Cond);
4818 -----------------------------
4819 -- Index_Checks_Suppressed --
4820 -----------------------------
4822 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
4824 if Present (E) and then Checks_May_Be_Suppressed (E) then
4825 return Is_Check_Suppressed (E, Index_Check);
4827 return Scope_Suppress (Index_Check);
4829 end Index_Checks_Suppressed;
4835 procedure Initialize is
4837 for J in Determine_Range_Cache_N'Range loop
4838 Determine_Range_Cache_N (J) := Empty;
4843 for J in Int range 1 .. All_Checks loop
4844 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
4848 -------------------------
4849 -- Insert_Range_Checks --
4850 -------------------------
4852 procedure Insert_Range_Checks
4853 (Checks : Check_Result;
4855 Suppress_Typ : Entity_Id;
4856 Static_Sloc : Source_Ptr := No_Location;
4857 Flag_Node : Node_Id := Empty;
4858 Do_Before : Boolean := False)
4860 Internal_Flag_Node : Node_Id := Flag_Node;
4861 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
4863 Check_Node : Node_Id;
4864 Checks_On : constant Boolean :=
4865 (not Index_Checks_Suppressed (Suppress_Typ))
4867 (not Range_Checks_Suppressed (Suppress_Typ));
4870 -- For now we just return if Checks_On is false, however this should be
4871 -- enhanced to check for an always True value in the condition and to
4872 -- generate a compilation warning???
4874 if not Expander_Active or else not Checks_On then
4878 if Static_Sloc = No_Location then
4879 Internal_Static_Sloc := Sloc (Node);
4882 if No (Flag_Node) then
4883 Internal_Flag_Node := Node;
4886 for J in 1 .. 2 loop
4887 exit when No (Checks (J));
4889 if Nkind (Checks (J)) = N_Raise_Constraint_Error
4890 and then Present (Condition (Checks (J)))
4892 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
4893 Check_Node := Checks (J);
4894 Mark_Rewrite_Insertion (Check_Node);
4897 Insert_Before_And_Analyze (Node, Check_Node);
4899 Insert_After_And_Analyze (Node, Check_Node);
4902 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
4907 Make_Raise_Constraint_Error (Internal_Static_Sloc,
4908 Reason => CE_Range_Check_Failed);
4909 Mark_Rewrite_Insertion (Check_Node);
4912 Insert_Before_And_Analyze (Node, Check_Node);
4914 Insert_After_And_Analyze (Node, Check_Node);
4918 end Insert_Range_Checks;
4920 ------------------------
4921 -- Insert_Valid_Check --
4922 ------------------------
4924 procedure Insert_Valid_Check (Expr : Node_Id) is
4925 Loc : constant Source_Ptr := Sloc (Expr);
4929 -- Do not insert if checks off, or if not checking validity
4931 if not Validity_Checks_On
4932 or else Range_Or_Validity_Checks_Suppressed (Expr)
4937 -- If we have a checked conversion, then validity check applies to
4938 -- the expression inside the conversion, not the result, since if
4939 -- the expression inside is valid, then so is the conversion result.
4942 while Nkind (Exp) = N_Type_Conversion loop
4943 Exp := Expression (Exp);
4946 -- We are about to insert the validity check for Exp. We save and
4947 -- reset the Do_Range_Check flag over this validity check, and then
4948 -- put it back for the final original reference (Exp may be rewritten).
4951 DRC : constant Boolean := Do_Range_Check (Exp);
4954 Set_Do_Range_Check (Exp, False);
4956 -- Insert the validity check. Note that we do this with validity
4957 -- checks turned off, to avoid recursion, we do not want validity
4958 -- checks on the validity checking code itself!
4962 Make_Raise_Constraint_Error (Loc,
4966 Make_Attribute_Reference (Loc,
4968 Duplicate_Subexpr_No_Checks (Exp, Name_Req => True),
4969 Attribute_Name => Name_Valid)),
4970 Reason => CE_Invalid_Data),
4971 Suppress => Validity_Check);
4973 -- If the expression is a a reference to an element of a bit-packed
4974 -- array, then it is rewritten as a renaming declaration. If the
4975 -- expression is an actual in a call, it has not been expanded,
4976 -- waiting for the proper point at which to do it. The same happens
4977 -- with renamings, so that we have to force the expansion now. This
4978 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
4981 if Is_Entity_Name (Exp)
4982 and then Nkind (Parent (Entity (Exp))) =
4983 N_Object_Renaming_Declaration
4986 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
4988 if Nkind (Old_Exp) = N_Indexed_Component
4989 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
4991 Expand_Packed_Element_Reference (Old_Exp);
4996 -- Put back the Do_Range_Check flag on the resulting (possibly
4997 -- rewritten) expression.
4999 -- Note: it might be thought that a validity check is not required
5000 -- when a range check is present, but that's not the case, because
5001 -- the back end is allowed to assume for the range check that the
5002 -- operand is within its declared range (an assumption that validity
5003 -- checking is all about NOT assuming!)
5005 -- Note: no need to worry about Possible_Local_Raise here, it will
5006 -- already have been called if original node has Do_Range_Check set.
5008 Set_Do_Range_Check (Exp, DRC);
5010 end Insert_Valid_Check;
5012 ----------------------------------
5013 -- Install_Null_Excluding_Check --
5014 ----------------------------------
5016 procedure Install_Null_Excluding_Check (N : Node_Id) is
5017 Loc : constant Source_Ptr := Sloc (N);
5018 Typ : constant Entity_Id := Etype (N);
5020 function In_Declarative_Region_Of_Subprogram_Body return Boolean;
5021 -- Determine whether node N, a reference to an *in* parameter, is
5022 -- inside the declarative region of the current subprogram body.
5024 procedure Mark_Non_Null;
5025 -- After installation of check, if the node in question is an entity
5026 -- name, then mark this entity as non-null if possible.
5028 ----------------------------------------------
5029 -- In_Declarative_Region_Of_Subprogram_Body --
5030 ----------------------------------------------
5032 function In_Declarative_Region_Of_Subprogram_Body return Boolean is
5033 E : constant Entity_Id := Entity (N);
5034 S : constant Entity_Id := Current_Scope;
5038 pragma Assert (Ekind (E) = E_In_Parameter);
5040 -- Two initial context checks. We must be inside a subprogram body
5041 -- with declarations and reference must not appear in nested scopes.
5043 if (Ekind (S) /= E_Function
5044 and then Ekind (S) /= E_Procedure)
5045 or else Scope (E) /= S
5050 S_Par := Parent (Parent (S));
5052 if Nkind (S_Par) /= N_Subprogram_Body
5053 or else No (Declarations (S_Par))
5063 -- Retrieve the declaration node of N (if any). Note that N
5064 -- may be a part of a complex initialization expression.
5068 while Present (P) loop
5070 -- While traversing the parent chain, we find that N
5071 -- belongs to a statement, thus it may never appear in
5072 -- a declarative region.
5074 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
5075 or else Nkind (P) = N_Procedure_Call_Statement
5080 if Nkind (P) in N_Declaration
5081 and then Nkind (P) not in N_Subprogram_Specification
5094 return List_Containing (N_Decl) = Declarations (S_Par);
5096 end In_Declarative_Region_Of_Subprogram_Body;
5102 procedure Mark_Non_Null is
5104 -- Only case of interest is if node N is an entity name
5106 if Is_Entity_Name (N) then
5108 -- For sure, we want to clear an indication that this is known to
5109 -- be null, since if we get past this check, it definitely is not!
5111 Set_Is_Known_Null (Entity (N), False);
5113 -- We can mark the entity as known to be non-null if either it is
5114 -- safe to capture the value, or in the case of an IN parameter,
5115 -- which is a constant, if the check we just installed is in the
5116 -- declarative region of the subprogram body. In this latter case,
5117 -- a check is decisive for the rest of the body, since we know we
5118 -- must complete all declarations before executing the body.
5120 if Safe_To_Capture_Value (N, Entity (N))
5122 (Ekind (Entity (N)) = E_In_Parameter
5123 and then In_Declarative_Region_Of_Subprogram_Body)
5125 Set_Is_Known_Non_Null (Entity (N));
5130 -- Start of processing for Install_Null_Excluding_Check
5133 pragma Assert (Is_Access_Type (Typ));
5135 -- No check inside a generic (why not???)
5137 if Inside_A_Generic then
5141 -- No check needed if known to be non-null
5143 if Known_Non_Null (N) then
5147 -- If known to be null, here is where we generate a compile time check
5149 if Known_Null (N) then
5150 Apply_Compile_Time_Constraint_Error
5152 "null value not allowed here?",
5153 CE_Access_Check_Failed);
5158 -- If entity is never assigned, for sure a warning is appropriate
5160 if Is_Entity_Name (N) then
5161 Check_Unset_Reference (N);
5164 -- No check needed if checks are suppressed on the range. Note that we
5165 -- don't set Is_Known_Non_Null in this case (we could legitimately do
5166 -- so, since the program is erroneous, but we don't like to casually
5167 -- propagate such conclusions from erroneosity).
5169 if Access_Checks_Suppressed (Typ) then
5173 -- No check needed for access to concurrent record types generated by
5174 -- the expander. This is not just an optimization (though it does indeed
5175 -- remove junk checks). It also avoids generation of junk warnings.
5177 if Nkind (N) in N_Has_Chars
5178 and then Chars (N) = Name_uObject
5179 and then Is_Concurrent_Record_Type
5180 (Directly_Designated_Type (Etype (N)))
5185 -- Otherwise install access check
5188 Make_Raise_Constraint_Error (Loc,
5191 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
5192 Right_Opnd => Make_Null (Loc)),
5193 Reason => CE_Access_Check_Failed));
5196 end Install_Null_Excluding_Check;
5198 --------------------------
5199 -- Install_Static_Check --
5200 --------------------------
5202 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
5203 Stat : constant Boolean := Is_Static_Expression (R_Cno);
5204 Typ : constant Entity_Id := Etype (R_Cno);
5208 Make_Raise_Constraint_Error (Loc,
5209 Reason => CE_Range_Check_Failed));
5210 Set_Analyzed (R_Cno);
5211 Set_Etype (R_Cno, Typ);
5212 Set_Raises_Constraint_Error (R_Cno);
5213 Set_Is_Static_Expression (R_Cno, Stat);
5214 end Install_Static_Check;
5216 ---------------------
5217 -- Kill_All_Checks --
5218 ---------------------
5220 procedure Kill_All_Checks is
5222 if Debug_Flag_CC then
5223 w ("Kill_All_Checks");
5226 -- We reset the number of saved checks to zero, and also modify all
5227 -- stack entries for statement ranges to indicate that the number of
5228 -- checks at each level is now zero.
5230 Num_Saved_Checks := 0;
5232 -- Note: the Int'Min here avoids any possibility of J being out of
5233 -- range when called from e.g. Conditional_Statements_Begin.
5235 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
5236 Saved_Checks_Stack (J) := 0;
5238 end Kill_All_Checks;
5244 procedure Kill_Checks (V : Entity_Id) is
5246 if Debug_Flag_CC then
5247 w ("Kill_Checks for entity", Int (V));
5250 for J in 1 .. Num_Saved_Checks loop
5251 if Saved_Checks (J).Entity = V then
5252 if Debug_Flag_CC then
5253 w (" Checks killed for saved check ", J);
5256 Saved_Checks (J).Killed := True;
5261 ------------------------------
5262 -- Length_Checks_Suppressed --
5263 ------------------------------
5265 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
5267 if Present (E) and then Checks_May_Be_Suppressed (E) then
5268 return Is_Check_Suppressed (E, Length_Check);
5270 return Scope_Suppress (Length_Check);
5272 end Length_Checks_Suppressed;
5274 --------------------------------
5275 -- Overflow_Checks_Suppressed --
5276 --------------------------------
5278 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
5280 if Present (E) and then Checks_May_Be_Suppressed (E) then
5281 return Is_Check_Suppressed (E, Overflow_Check);
5283 return Scope_Suppress (Overflow_Check);
5285 end Overflow_Checks_Suppressed;
5286 -----------------------------
5287 -- Range_Checks_Suppressed --
5288 -----------------------------
5290 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
5294 -- Note: for now we always suppress range checks on Vax float types,
5295 -- since Gigi does not know how to generate these checks.
5297 if Vax_Float (E) then
5299 elsif Kill_Range_Checks (E) then
5301 elsif Checks_May_Be_Suppressed (E) then
5302 return Is_Check_Suppressed (E, Range_Check);
5306 return Scope_Suppress (Range_Check);
5307 end Range_Checks_Suppressed;
5309 -----------------------------------------
5310 -- Range_Or_Validity_Checks_Suppressed --
5311 -----------------------------------------
5313 -- Note: the coding would be simpler here if we simply made appropriate
5314 -- calls to Range/Validity_Checks_Suppressed, but that would result in
5315 -- duplicated checks which we prefer to avoid.
5317 function Range_Or_Validity_Checks_Suppressed
5318 (Expr : Node_Id) return Boolean
5321 -- Immediate return if scope checks suppressed for either check
5323 if Scope_Suppress (Range_Check) or Scope_Suppress (Validity_Check) then
5327 -- If no expression, that's odd, decide that checks are suppressed,
5328 -- since we don't want anyone trying to do checks in this case, which
5329 -- is most likely the result of some other error.
5335 -- Expression is present, so perform suppress checks on type
5338 Typ : constant Entity_Id := Etype (Expr);
5340 if Vax_Float (Typ) then
5342 elsif Checks_May_Be_Suppressed (Typ)
5343 and then (Is_Check_Suppressed (Typ, Range_Check)
5345 Is_Check_Suppressed (Typ, Validity_Check))
5351 -- If expression is an entity name, perform checks on this entity
5353 if Is_Entity_Name (Expr) then
5355 Ent : constant Entity_Id := Entity (Expr);
5357 if Checks_May_Be_Suppressed (Ent) then
5358 return Is_Check_Suppressed (Ent, Range_Check)
5359 or else Is_Check_Suppressed (Ent, Validity_Check);
5364 -- If we fall through, no checks suppressed
5367 end Range_Or_Validity_Checks_Suppressed;
5373 procedure Remove_Checks (Expr : Node_Id) is
5374 function Process (N : Node_Id) return Traverse_Result;
5375 -- Process a single node during the traversal
5377 procedure Traverse is new Traverse_Proc (Process);
5378 -- The traversal procedure itself
5384 function Process (N : Node_Id) return Traverse_Result is
5386 if Nkind (N) not in N_Subexpr then
5390 Set_Do_Range_Check (N, False);
5394 Traverse (Left_Opnd (N));
5397 when N_Attribute_Reference =>
5398 Set_Do_Overflow_Check (N, False);
5400 when N_Function_Call =>
5401 Set_Do_Tag_Check (N, False);
5404 Set_Do_Overflow_Check (N, False);
5408 Set_Do_Division_Check (N, False);
5411 Set_Do_Length_Check (N, False);
5414 Set_Do_Division_Check (N, False);
5417 Set_Do_Length_Check (N, False);
5420 Set_Do_Division_Check (N, False);
5423 Set_Do_Length_Check (N, False);
5430 Traverse (Left_Opnd (N));
5433 when N_Selected_Component =>
5434 Set_Do_Discriminant_Check (N, False);
5436 when N_Type_Conversion =>
5437 Set_Do_Length_Check (N, False);
5438 Set_Do_Tag_Check (N, False);
5439 Set_Do_Overflow_Check (N, False);
5448 -- Start of processing for Remove_Checks
5454 ----------------------------
5455 -- Selected_Length_Checks --
5456 ----------------------------
5458 function Selected_Length_Checks
5460 Target_Typ : Entity_Id;
5461 Source_Typ : Entity_Id;
5462 Warn_Node : Node_Id) return Check_Result
5464 Loc : constant Source_Ptr := Sloc (Ck_Node);
5467 Expr_Actual : Node_Id;
5469 Cond : Node_Id := Empty;
5470 Do_Access : Boolean := False;
5471 Wnode : Node_Id := Warn_Node;
5472 Ret_Result : Check_Result := (Empty, Empty);
5473 Num_Checks : Natural := 0;
5475 procedure Add_Check (N : Node_Id);
5476 -- Adds the action given to Ret_Result if N is non-Empty
5478 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
5479 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
5480 -- Comments required ???
5482 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
5483 -- True for equal literals and for nodes that denote the same constant
5484 -- entity, even if its value is not a static constant. This includes the
5485 -- case of a discriminal reference within an init proc. Removes some
5486 -- obviously superfluous checks.
5488 function Length_E_Cond
5489 (Exptyp : Entity_Id;
5491 Indx : Nat) return Node_Id;
5492 -- Returns expression to compute:
5493 -- Typ'Length /= Exptyp'Length
5495 function Length_N_Cond
5498 Indx : Nat) return Node_Id;
5499 -- Returns expression to compute:
5500 -- Typ'Length /= Expr'Length
5506 procedure Add_Check (N : Node_Id) is
5510 -- For now, ignore attempt to place more than 2 checks ???
5512 if Num_Checks = 2 then
5516 pragma Assert (Num_Checks <= 1);
5517 Num_Checks := Num_Checks + 1;
5518 Ret_Result (Num_Checks) := N;
5526 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
5527 SE : constant Entity_Id := Scope (E);
5529 E1 : Entity_Id := E;
5532 if Ekind (Scope (E)) = E_Record_Type
5533 and then Has_Discriminants (Scope (E))
5535 N := Build_Discriminal_Subtype_Of_Component (E);
5538 Insert_Action (Ck_Node, N);
5539 E1 := Defining_Identifier (N);
5543 if Ekind (E1) = E_String_Literal_Subtype then
5545 Make_Integer_Literal (Loc,
5546 Intval => String_Literal_Length (E1));
5548 elsif SE /= Standard_Standard
5549 and then Ekind (Scope (SE)) = E_Protected_Type
5550 and then Has_Discriminants (Scope (SE))
5551 and then Has_Completion (Scope (SE))
5552 and then not Inside_Init_Proc
5554 -- If the type whose length is needed is a private component
5555 -- constrained by a discriminant, we must expand the 'Length
5556 -- attribute into an explicit computation, using the discriminal
5557 -- of the current protected operation. This is because the actual
5558 -- type of the prival is constructed after the protected opera-
5559 -- tion has been fully expanded.
5562 Indx_Type : Node_Id;
5565 Do_Expand : Boolean := False;
5568 Indx_Type := First_Index (E);
5570 for J in 1 .. Indx - 1 loop
5571 Next_Index (Indx_Type);
5574 Get_Index_Bounds (Indx_Type, Lo, Hi);
5576 if Nkind (Lo) = N_Identifier
5577 and then Ekind (Entity (Lo)) = E_In_Parameter
5579 Lo := Get_Discriminal (E, Lo);
5583 if Nkind (Hi) = N_Identifier
5584 and then Ekind (Entity (Hi)) = E_In_Parameter
5586 Hi := Get_Discriminal (E, Hi);
5591 if not Is_Entity_Name (Lo) then
5592 Lo := Duplicate_Subexpr_No_Checks (Lo);
5595 if not Is_Entity_Name (Hi) then
5596 Lo := Duplicate_Subexpr_No_Checks (Hi);
5602 Make_Op_Subtract (Loc,
5606 Right_Opnd => Make_Integer_Literal (Loc, 1));
5611 Make_Attribute_Reference (Loc,
5612 Attribute_Name => Name_Length,
5614 New_Occurrence_Of (E1, Loc));
5617 Set_Expressions (N, New_List (
5618 Make_Integer_Literal (Loc, Indx)));
5627 Make_Attribute_Reference (Loc,
5628 Attribute_Name => Name_Length,
5630 New_Occurrence_Of (E1, Loc));
5633 Set_Expressions (N, New_List (
5634 Make_Integer_Literal (Loc, Indx)));
5645 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
5648 Make_Attribute_Reference (Loc,
5649 Attribute_Name => Name_Length,
5651 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
5652 Expressions => New_List (
5653 Make_Integer_Literal (Loc, Indx)));
5660 function Length_E_Cond
5661 (Exptyp : Entity_Id;
5663 Indx : Nat) return Node_Id
5668 Left_Opnd => Get_E_Length (Typ, Indx),
5669 Right_Opnd => Get_E_Length (Exptyp, Indx));
5676 function Length_N_Cond
5679 Indx : Nat) return Node_Id
5684 Left_Opnd => Get_E_Length (Typ, Indx),
5685 Right_Opnd => Get_N_Length (Expr, Indx));
5692 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
5695 (Nkind (L) = N_Integer_Literal
5696 and then Nkind (R) = N_Integer_Literal
5697 and then Intval (L) = Intval (R))
5701 and then Ekind (Entity (L)) = E_Constant
5702 and then ((Is_Entity_Name (R)
5703 and then Entity (L) = Entity (R))
5705 (Nkind (R) = N_Type_Conversion
5706 and then Is_Entity_Name (Expression (R))
5707 and then Entity (L) = Entity (Expression (R)))))
5711 and then Ekind (Entity (R)) = E_Constant
5712 and then Nkind (L) = N_Type_Conversion
5713 and then Is_Entity_Name (Expression (L))
5714 and then Entity (R) = Entity (Expression (L)))
5718 and then Is_Entity_Name (R)
5719 and then Entity (L) = Entity (R)
5720 and then Ekind (Entity (L)) = E_In_Parameter
5721 and then Inside_Init_Proc);
5724 -- Start of processing for Selected_Length_Checks
5727 if not Expander_Active then
5731 if Target_Typ = Any_Type
5732 or else Target_Typ = Any_Composite
5733 or else Raises_Constraint_Error (Ck_Node)
5742 T_Typ := Target_Typ;
5744 if No (Source_Typ) then
5745 S_Typ := Etype (Ck_Node);
5747 S_Typ := Source_Typ;
5750 if S_Typ = Any_Type or else S_Typ = Any_Composite then
5754 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
5755 S_Typ := Designated_Type (S_Typ);
5756 T_Typ := Designated_Type (T_Typ);
5759 -- A simple optimization for the null case
5761 if Known_Null (Ck_Node) then
5766 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
5767 if Is_Constrained (T_Typ) then
5769 -- The checking code to be generated will freeze the
5770 -- corresponding array type. However, we must freeze the
5771 -- type now, so that the freeze node does not appear within
5772 -- the generated condional expression, but ahead of it.
5774 Freeze_Before (Ck_Node, T_Typ);
5776 Expr_Actual := Get_Referenced_Object (Ck_Node);
5777 Exptyp := Get_Actual_Subtype (Ck_Node);
5779 if Is_Access_Type (Exptyp) then
5780 Exptyp := Designated_Type (Exptyp);
5783 -- String_Literal case. This needs to be handled specially be-
5784 -- cause no index types are available for string literals. The
5785 -- condition is simply:
5787 -- T_Typ'Length = string-literal-length
5789 if Nkind (Expr_Actual) = N_String_Literal
5790 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
5794 Left_Opnd => Get_E_Length (T_Typ, 1),
5796 Make_Integer_Literal (Loc,
5798 String_Literal_Length (Etype (Expr_Actual))));
5800 -- General array case. Here we have a usable actual subtype for
5801 -- the expression, and the condition is built from the two types
5804 -- T_Typ'Length /= Exptyp'Length or else
5805 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
5806 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
5809 elsif Is_Constrained (Exptyp) then
5811 Ndims : constant Nat := Number_Dimensions (T_Typ);
5824 -- At the library level, we need to ensure that the type of
5825 -- the object is elaborated before the check itself is
5826 -- emitted. This is only done if the object is in the
5827 -- current compilation unit, otherwise the type is frozen
5828 -- and elaborated in its unit.
5830 if Is_Itype (Exptyp)
5832 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
5834 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
5835 and then In_Open_Scopes (Scope (Exptyp))
5837 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
5838 Set_Itype (Ref_Node, Exptyp);
5839 Insert_Action (Ck_Node, Ref_Node);
5842 L_Index := First_Index (T_Typ);
5843 R_Index := First_Index (Exptyp);
5845 for Indx in 1 .. Ndims loop
5846 if not (Nkind (L_Index) = N_Raise_Constraint_Error
5848 Nkind (R_Index) = N_Raise_Constraint_Error)
5850 Get_Index_Bounds (L_Index, L_Low, L_High);
5851 Get_Index_Bounds (R_Index, R_Low, R_High);
5853 -- Deal with compile time length check. Note that we
5854 -- skip this in the access case, because the access
5855 -- value may be null, so we cannot know statically.
5858 and then Compile_Time_Known_Value (L_Low)
5859 and then Compile_Time_Known_Value (L_High)
5860 and then Compile_Time_Known_Value (R_Low)
5861 and then Compile_Time_Known_Value (R_High)
5863 if Expr_Value (L_High) >= Expr_Value (L_Low) then
5864 L_Length := Expr_Value (L_High) -
5865 Expr_Value (L_Low) + 1;
5867 L_Length := UI_From_Int (0);
5870 if Expr_Value (R_High) >= Expr_Value (R_Low) then
5871 R_Length := Expr_Value (R_High) -
5872 Expr_Value (R_Low) + 1;
5874 R_Length := UI_From_Int (0);
5877 if L_Length > R_Length then
5879 (Compile_Time_Constraint_Error
5880 (Wnode, "too few elements for}?", T_Typ));
5882 elsif L_Length < R_Length then
5884 (Compile_Time_Constraint_Error
5885 (Wnode, "too many elements for}?", T_Typ));
5888 -- The comparison for an individual index subtype
5889 -- is omitted if the corresponding index subtypes
5890 -- statically match, since the result is known to
5891 -- be true. Note that this test is worth while even
5892 -- though we do static evaluation, because non-static
5893 -- subtypes can statically match.
5896 Subtypes_Statically_Match
5897 (Etype (L_Index), Etype (R_Index))
5900 (Same_Bounds (L_Low, R_Low)
5901 and then Same_Bounds (L_High, R_High))
5904 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
5913 -- Handle cases where we do not get a usable actual subtype that
5914 -- is constrained. This happens for example in the function call
5915 -- and explicit dereference cases. In these cases, we have to get
5916 -- the length or range from the expression itself, making sure we
5917 -- do not evaluate it more than once.
5919 -- Here Ck_Node is the original expression, or more properly the
5920 -- result of applying Duplicate_Expr to the original tree, forcing
5921 -- the result to be a name.
5925 Ndims : constant Nat := Number_Dimensions (T_Typ);
5928 -- Build the condition for the explicit dereference case
5930 for Indx in 1 .. Ndims loop
5932 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
5939 -- Construct the test and insert into the tree
5941 if Present (Cond) then
5943 Cond := Guard_Access (Cond, Loc, Ck_Node);
5947 (Make_Raise_Constraint_Error (Loc,
5949 Reason => CE_Length_Check_Failed));
5953 end Selected_Length_Checks;
5955 ---------------------------
5956 -- Selected_Range_Checks --
5957 ---------------------------
5959 function Selected_Range_Checks
5961 Target_Typ : Entity_Id;
5962 Source_Typ : Entity_Id;
5963 Warn_Node : Node_Id) return Check_Result
5965 Loc : constant Source_Ptr := Sloc (Ck_Node);
5968 Expr_Actual : Node_Id;
5970 Cond : Node_Id := Empty;
5971 Do_Access : Boolean := False;
5972 Wnode : Node_Id := Warn_Node;
5973 Ret_Result : Check_Result := (Empty, Empty);
5974 Num_Checks : Integer := 0;
5976 procedure Add_Check (N : Node_Id);
5977 -- Adds the action given to Ret_Result if N is non-Empty
5979 function Discrete_Range_Cond
5981 Typ : Entity_Id) return Node_Id;
5982 -- Returns expression to compute:
5983 -- Low_Bound (Expr) < Typ'First
5985 -- High_Bound (Expr) > Typ'Last
5987 function Discrete_Expr_Cond
5989 Typ : Entity_Id) return Node_Id;
5990 -- Returns expression to compute:
5995 function Get_E_First_Or_Last
5998 Nam : Name_Id) return Node_Id;
5999 -- Returns expression to compute:
6000 -- E'First or E'Last
6002 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
6003 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
6004 -- Returns expression to compute:
6005 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
6007 function Range_E_Cond
6008 (Exptyp : Entity_Id;
6012 -- Returns expression to compute:
6013 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
6015 function Range_Equal_E_Cond
6016 (Exptyp : Entity_Id;
6018 Indx : Nat) return Node_Id;
6019 -- Returns expression to compute:
6020 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
6022 function Range_N_Cond
6025 Indx : Nat) return Node_Id;
6026 -- Return expression to compute:
6027 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
6033 procedure Add_Check (N : Node_Id) is
6037 -- For now, ignore attempt to place more than 2 checks ???
6039 if Num_Checks = 2 then
6043 pragma Assert (Num_Checks <= 1);
6044 Num_Checks := Num_Checks + 1;
6045 Ret_Result (Num_Checks) := N;
6049 -------------------------
6050 -- Discrete_Expr_Cond --
6051 -------------------------
6053 function Discrete_Expr_Cond
6055 Typ : Entity_Id) return Node_Id
6063 Convert_To (Base_Type (Typ),
6064 Duplicate_Subexpr_No_Checks (Expr)),
6066 Convert_To (Base_Type (Typ),
6067 Get_E_First_Or_Last (Typ, 0, Name_First))),
6072 Convert_To (Base_Type (Typ),
6073 Duplicate_Subexpr_No_Checks (Expr)),
6077 Get_E_First_Or_Last (Typ, 0, Name_Last))));
6078 end Discrete_Expr_Cond;
6080 -------------------------
6081 -- Discrete_Range_Cond --
6082 -------------------------
6084 function Discrete_Range_Cond
6086 Typ : Entity_Id) return Node_Id
6088 LB : Node_Id := Low_Bound (Expr);
6089 HB : Node_Id := High_Bound (Expr);
6091 Left_Opnd : Node_Id;
6092 Right_Opnd : Node_Id;
6095 if Nkind (LB) = N_Identifier
6096 and then Ekind (Entity (LB)) = E_Discriminant
6098 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6101 if Nkind (HB) = N_Identifier
6102 and then Ekind (Entity (HB)) = E_Discriminant
6104 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6111 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
6115 (Base_Type (Typ), Get_E_First_Or_Last (Typ, 0, Name_First)));
6117 if Base_Type (Typ) = Typ then
6120 elsif Compile_Time_Known_Value (High_Bound (Scalar_Range (Typ)))
6122 Compile_Time_Known_Value (High_Bound (Scalar_Range
6125 if Is_Floating_Point_Type (Typ) then
6126 if Expr_Value_R (High_Bound (Scalar_Range (Typ))) =
6127 Expr_Value_R (High_Bound (Scalar_Range (Base_Type (Typ))))
6133 if Expr_Value (High_Bound (Scalar_Range (Typ))) =
6134 Expr_Value (High_Bound (Scalar_Range (Base_Type (Typ))))
6145 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
6150 Get_E_First_Or_Last (Typ, 0, Name_Last)));
6152 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
6153 end Discrete_Range_Cond;
6155 -------------------------
6156 -- Get_E_First_Or_Last --
6157 -------------------------
6159 function Get_E_First_Or_Last
6162 Nam : Name_Id) return Node_Id
6170 if Is_Array_Type (E) then
6171 N := First_Index (E);
6173 for J in 2 .. Indx loop
6178 N := Scalar_Range (E);
6181 if Nkind (N) = N_Subtype_Indication then
6182 LB := Low_Bound (Range_Expression (Constraint (N)));
6183 HB := High_Bound (Range_Expression (Constraint (N)));
6185 elsif Is_Entity_Name (N) then
6186 LB := Type_Low_Bound (Etype (N));
6187 HB := Type_High_Bound (Etype (N));
6190 LB := Low_Bound (N);
6191 HB := High_Bound (N);
6194 if Nam = Name_First then
6200 if Nkind (Bound) = N_Identifier
6201 and then Ekind (Entity (Bound)) = E_Discriminant
6203 -- If this is a task discriminant, and we are the body, we must
6204 -- retrieve the corresponding body discriminal. This is another
6205 -- consequence of the early creation of discriminals, and the
6206 -- need to generate constraint checks before their declarations
6207 -- are made visible.
6209 if Is_Concurrent_Record_Type (Scope (Entity (Bound))) then
6211 Tsk : constant Entity_Id :=
6212 Corresponding_Concurrent_Type
6213 (Scope (Entity (Bound)));
6217 if In_Open_Scopes (Tsk)
6218 and then Has_Completion (Tsk)
6220 -- Find discriminant of original task, and use its
6221 -- current discriminal, which is the renaming within
6224 Disc := First_Discriminant (Tsk);
6225 while Present (Disc) loop
6226 if Chars (Disc) = Chars (Entity (Bound)) then
6227 Set_Scope (Discriminal (Disc), Tsk);
6228 return New_Occurrence_Of (Discriminal (Disc), Loc);
6231 Next_Discriminant (Disc);
6234 -- That loop should always succeed in finding a matching
6235 -- entry and returning. Fatal error if not.
6237 raise Program_Error;
6241 New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6245 return New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6248 elsif Nkind (Bound) = N_Identifier
6249 and then Ekind (Entity (Bound)) = E_In_Parameter
6250 and then not Inside_Init_Proc
6252 return Get_Discriminal (E, Bound);
6254 elsif Nkind (Bound) = N_Integer_Literal then
6255 return Make_Integer_Literal (Loc, Intval (Bound));
6257 -- Case of a bound rewritten to an N_Raise_Constraint_Error node
6258 -- because it is an out-of-range value. Duplicate_Subexpr cannot be
6259 -- called on this node because an N_Raise_Constraint_Error is not
6260 -- side effect free, and we may not assume that we are in the proper
6261 -- context to remove side effects on it at the point of reference.
6263 elsif Nkind (Bound) = N_Raise_Constraint_Error then
6264 return New_Copy_Tree (Bound);
6267 return Duplicate_Subexpr_No_Checks (Bound);
6269 end Get_E_First_Or_Last;
6275 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
6278 Make_Attribute_Reference (Loc,
6279 Attribute_Name => Name_First,
6281 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6282 Expressions => New_List (
6283 Make_Integer_Literal (Loc, Indx)));
6290 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
6293 Make_Attribute_Reference (Loc,
6294 Attribute_Name => Name_Last,
6296 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6297 Expressions => New_List (
6298 Make_Integer_Literal (Loc, Indx)));
6305 function Range_E_Cond
6306 (Exptyp : Entity_Id;
6308 Indx : Nat) return Node_Id
6315 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6316 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6320 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6321 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6324 ------------------------
6325 -- Range_Equal_E_Cond --
6326 ------------------------
6328 function Range_Equal_E_Cond
6329 (Exptyp : Entity_Id;
6331 Indx : Nat) return Node_Id
6338 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6339 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6342 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6343 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6344 end Range_Equal_E_Cond;
6350 function Range_N_Cond
6353 Indx : Nat) return Node_Id
6360 Left_Opnd => Get_N_First (Expr, Indx),
6361 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6365 Left_Opnd => Get_N_Last (Expr, Indx),
6366 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6369 -- Start of processing for Selected_Range_Checks
6372 if not Expander_Active then
6376 if Target_Typ = Any_Type
6377 or else Target_Typ = Any_Composite
6378 or else Raises_Constraint_Error (Ck_Node)
6387 T_Typ := Target_Typ;
6389 if No (Source_Typ) then
6390 S_Typ := Etype (Ck_Node);
6392 S_Typ := Source_Typ;
6395 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6399 -- The order of evaluating T_Typ before S_Typ seems to be critical
6400 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
6401 -- in, and since Node can be an N_Range node, it might be invalid.
6402 -- Should there be an assert check somewhere for taking the Etype of
6403 -- an N_Range node ???
6405 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6406 S_Typ := Designated_Type (S_Typ);
6407 T_Typ := Designated_Type (T_Typ);
6410 -- A simple optimization for the null case
6412 if Known_Null (Ck_Node) then
6417 -- For an N_Range Node, check for a null range and then if not
6418 -- null generate a range check action.
6420 if Nkind (Ck_Node) = N_Range then
6422 -- There's no point in checking a range against itself
6424 if Ck_Node = Scalar_Range (T_Typ) then
6429 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
6430 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
6431 LB : constant Node_Id := Low_Bound (Ck_Node);
6432 HB : constant Node_Id := High_Bound (Ck_Node);
6433 Null_Range : Boolean;
6435 Out_Of_Range_L : Boolean;
6436 Out_Of_Range_H : Boolean;
6439 -- Check for case where everything is static and we can
6440 -- do the check at compile time. This is skipped if we
6441 -- have an access type, since the access value may be null.
6443 -- ??? This code can be improved since you only need to know
6444 -- that the two respective bounds (LB & T_LB or HB & T_HB)
6445 -- are known at compile time to emit pertinent messages.
6447 if Compile_Time_Known_Value (LB)
6448 and then Compile_Time_Known_Value (HB)
6449 and then Compile_Time_Known_Value (T_LB)
6450 and then Compile_Time_Known_Value (T_HB)
6451 and then not Do_Access
6453 -- Floating-point case
6455 if Is_Floating_Point_Type (S_Typ) then
6456 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
6458 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
6460 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
6463 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
6465 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
6467 -- Fixed or discrete type case
6470 Null_Range := Expr_Value (HB) < Expr_Value (LB);
6472 (Expr_Value (LB) < Expr_Value (T_LB))
6474 (Expr_Value (LB) > Expr_Value (T_HB));
6477 (Expr_Value (HB) > Expr_Value (T_HB))
6479 (Expr_Value (HB) < Expr_Value (T_LB));
6482 if not Null_Range then
6483 if Out_Of_Range_L then
6484 if No (Warn_Node) then
6486 (Compile_Time_Constraint_Error
6487 (Low_Bound (Ck_Node),
6488 "static value out of range of}?", T_Typ));
6492 (Compile_Time_Constraint_Error
6494 "static range out of bounds of}?", T_Typ));
6498 if Out_Of_Range_H then
6499 if No (Warn_Node) then
6501 (Compile_Time_Constraint_Error
6502 (High_Bound (Ck_Node),
6503 "static value out of range of}?", T_Typ));
6507 (Compile_Time_Constraint_Error
6509 "static range out of bounds of}?", T_Typ));
6517 LB : Node_Id := Low_Bound (Ck_Node);
6518 HB : Node_Id := High_Bound (Ck_Node);
6521 -- If either bound is a discriminant and we are within the
6522 -- record declaration, it is a use of the discriminant in a
6523 -- constraint of a component, and nothing can be checked
6524 -- here. The check will be emitted within the init proc.
6525 -- Before then, the discriminal has no real meaning.
6526 -- Similarly, if the entity is a discriminal, there is no
6527 -- check to perform yet.
6529 -- The same holds within a discriminated synchronized type,
6530 -- where the discriminant may constrain a component or an
6533 if Nkind (LB) = N_Identifier
6534 and then Denotes_Discriminant (LB, True)
6536 if Current_Scope = Scope (Entity (LB))
6537 or else Is_Concurrent_Type (Current_Scope)
6538 or else Ekind (Entity (LB)) /= E_Discriminant
6543 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6547 if Nkind (HB) = N_Identifier
6548 and then Denotes_Discriminant (HB, True)
6550 if Current_Scope = Scope (Entity (HB))
6551 or else Is_Concurrent_Type (Current_Scope)
6552 or else Ekind (Entity (HB)) /= E_Discriminant
6557 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6561 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
6562 Set_Paren_Count (Cond, 1);
6568 Left_Opnd => Duplicate_Subexpr_No_Checks (HB),
6569 Right_Opnd => Duplicate_Subexpr_No_Checks (LB)),
6570 Right_Opnd => Cond);
6575 elsif Is_Scalar_Type (S_Typ) then
6577 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
6578 -- except the above simply sets a flag in the node and lets
6579 -- gigi generate the check base on the Etype of the expression.
6580 -- Sometimes, however we want to do a dynamic check against an
6581 -- arbitrary target type, so we do that here.
6583 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
6584 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6586 -- For literals, we can tell if the constraint error will be
6587 -- raised at compile time, so we never need a dynamic check, but
6588 -- if the exception will be raised, then post the usual warning,
6589 -- and replace the literal with a raise constraint error
6590 -- expression. As usual, skip this for access types
6592 elsif Compile_Time_Known_Value (Ck_Node)
6593 and then not Do_Access
6596 LB : constant Node_Id := Type_Low_Bound (T_Typ);
6597 UB : constant Node_Id := Type_High_Bound (T_Typ);
6599 Out_Of_Range : Boolean;
6600 Static_Bounds : constant Boolean :=
6601 Compile_Time_Known_Value (LB)
6602 and Compile_Time_Known_Value (UB);
6605 -- Following range tests should use Sem_Eval routine ???
6607 if Static_Bounds then
6608 if Is_Floating_Point_Type (S_Typ) then
6610 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
6612 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
6614 else -- fixed or discrete type
6616 Expr_Value (Ck_Node) < Expr_Value (LB)
6618 Expr_Value (Ck_Node) > Expr_Value (UB);
6621 -- Bounds of the type are static and the literal is
6622 -- out of range so make a warning message.
6624 if Out_Of_Range then
6625 if No (Warn_Node) then
6627 (Compile_Time_Constraint_Error
6629 "static value out of range of}?", T_Typ));
6633 (Compile_Time_Constraint_Error
6635 "static value out of range of}?", T_Typ));
6640 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6644 -- Here for the case of a non-static expression, we need a runtime
6645 -- check unless the source type range is guaranteed to be in the
6646 -- range of the target type.
6649 if not In_Subrange_Of (S_Typ, T_Typ) then
6650 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6655 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6656 if Is_Constrained (T_Typ) then
6658 Expr_Actual := Get_Referenced_Object (Ck_Node);
6659 Exptyp := Get_Actual_Subtype (Expr_Actual);
6661 if Is_Access_Type (Exptyp) then
6662 Exptyp := Designated_Type (Exptyp);
6665 -- String_Literal case. This needs to be handled specially be-
6666 -- cause no index types are available for string literals. The
6667 -- condition is simply:
6669 -- T_Typ'Length = string-literal-length
6671 if Nkind (Expr_Actual) = N_String_Literal then
6674 -- General array case. Here we have a usable actual subtype for
6675 -- the expression, and the condition is built from the two types
6677 -- T_Typ'First < Exptyp'First or else
6678 -- T_Typ'Last > Exptyp'Last or else
6679 -- T_Typ'First(1) < Exptyp'First(1) or else
6680 -- T_Typ'Last(1) > Exptyp'Last(1) or else
6683 elsif Is_Constrained (Exptyp) then
6685 Ndims : constant Nat := Number_Dimensions (T_Typ);
6691 L_Index := First_Index (T_Typ);
6692 R_Index := First_Index (Exptyp);
6694 for Indx in 1 .. Ndims loop
6695 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6697 Nkind (R_Index) = N_Raise_Constraint_Error)
6699 -- Deal with compile time length check. Note that we
6700 -- skip this in the access case, because the access
6701 -- value may be null, so we cannot know statically.
6704 Subtypes_Statically_Match
6705 (Etype (L_Index), Etype (R_Index))
6707 -- If the target type is constrained then we
6708 -- have to check for exact equality of bounds
6709 -- (required for qualified expressions).
6711 if Is_Constrained (T_Typ) then
6714 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
6717 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
6728 -- Handle cases where we do not get a usable actual subtype that
6729 -- is constrained. This happens for example in the function call
6730 -- and explicit dereference cases. In these cases, we have to get
6731 -- the length or range from the expression itself, making sure we
6732 -- do not evaluate it more than once.
6734 -- Here Ck_Node is the original expression, or more properly the
6735 -- result of applying Duplicate_Expr to the original tree,
6736 -- forcing the result to be a name.
6740 Ndims : constant Nat := Number_Dimensions (T_Typ);
6743 -- Build the condition for the explicit dereference case
6745 for Indx in 1 .. Ndims loop
6747 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
6754 -- For a conversion to an unconstrained array type, generate an
6755 -- Action to check that the bounds of the source value are within
6756 -- the constraints imposed by the target type (RM 4.6(38)). No
6757 -- check is needed for a conversion to an access to unconstrained
6758 -- array type, as 4.6(24.15/2) requires the designated subtypes
6759 -- of the two access types to statically match.
6761 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
6762 and then not Do_Access
6765 Opnd_Index : Node_Id;
6766 Targ_Index : Node_Id;
6767 Opnd_Range : Node_Id;
6770 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
6771 Targ_Index := First_Index (T_Typ);
6773 while Present (Opnd_Index) loop
6775 -- If the index is a range, use its bounds. If it is an
6776 -- entity (as will be the case if it is a named subtype
6777 -- or an itype created for a slice) retrieve its range.
6779 if Is_Entity_Name (Opnd_Index)
6780 and then Is_Type (Entity (Opnd_Index))
6782 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
6784 Opnd_Range := Opnd_Index;
6787 if Nkind (Opnd_Range) = N_Range then
6789 (Low_Bound (Opnd_Range), Etype (Targ_Index))
6792 (High_Bound (Opnd_Range), Etype (Targ_Index))
6796 -- If null range, no check needed
6799 Compile_Time_Known_Value (High_Bound (Opnd_Range))
6801 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
6803 Expr_Value (High_Bound (Opnd_Range)) <
6804 Expr_Value (Low_Bound (Opnd_Range))
6808 elsif Is_Out_Of_Range
6809 (Low_Bound (Opnd_Range), Etype (Targ_Index))
6812 (High_Bound (Opnd_Range), Etype (Targ_Index))
6815 (Compile_Time_Constraint_Error
6816 (Wnode, "value out of range of}?", T_Typ));
6822 (Opnd_Range, Etype (Targ_Index)));
6826 Next_Index (Opnd_Index);
6827 Next_Index (Targ_Index);
6834 -- Construct the test and insert into the tree
6836 if Present (Cond) then
6838 Cond := Guard_Access (Cond, Loc, Ck_Node);
6842 (Make_Raise_Constraint_Error (Loc,
6844 Reason => CE_Range_Check_Failed));
6848 end Selected_Range_Checks;
6850 -------------------------------
6851 -- Storage_Checks_Suppressed --
6852 -------------------------------
6854 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
6856 if Present (E) and then Checks_May_Be_Suppressed (E) then
6857 return Is_Check_Suppressed (E, Storage_Check);
6859 return Scope_Suppress (Storage_Check);
6861 end Storage_Checks_Suppressed;
6863 ---------------------------
6864 -- Tag_Checks_Suppressed --
6865 ---------------------------
6867 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
6870 if Kill_Tag_Checks (E) then
6872 elsif Checks_May_Be_Suppressed (E) then
6873 return Is_Check_Suppressed (E, Tag_Check);
6877 return Scope_Suppress (Tag_Check);
6878 end Tag_Checks_Suppressed;
6880 --------------------------
6881 -- Validity_Check_Range --
6882 --------------------------
6884 procedure Validity_Check_Range (N : Node_Id) is
6886 if Validity_Checks_On and Validity_Check_Operands then
6887 if Nkind (N) = N_Range then
6888 Ensure_Valid (Low_Bound (N));
6889 Ensure_Valid (High_Bound (N));
6892 end Validity_Check_Range;
6894 --------------------------------
6895 -- Validity_Checks_Suppressed --
6896 --------------------------------
6898 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
6900 if Present (E) and then Checks_May_Be_Suppressed (E) then
6901 return Is_Check_Suppressed (E, Validity_Check);
6903 return Scope_Suppress (Validity_Check);
6905 end Validity_Checks_Suppressed;