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 -- No check if accessing the Offset_To_Top component of a dispatch
454 -- table. They are safe by construction.
456 if Present (Etype (P))
457 and then RTU_Loaded (Ada_Tags)
458 and then RTE_Available (RE_Offset_To_Top_Ptr)
459 and then Etype (P) = RTE (RE_Offset_To_Top_Ptr)
464 -- Otherwise go ahead and install the check
466 Install_Null_Excluding_Check (P);
467 end Apply_Access_Check;
469 -------------------------------
470 -- Apply_Accessibility_Check --
471 -------------------------------
473 procedure Apply_Accessibility_Check (N : Node_Id; Typ : Entity_Id) is
474 Loc : constant Source_Ptr := Sloc (N);
475 Param_Ent : constant Entity_Id := Param_Entity (N);
476 Param_Level : Node_Id;
477 Type_Level : Node_Id;
480 if Inside_A_Generic then
483 -- Only apply the run-time check if the access parameter
484 -- has an associated extra access level parameter and
485 -- when the level of the type is less deep than the level
486 -- of the access parameter.
488 elsif Present (Param_Ent)
489 and then Present (Extra_Accessibility (Param_Ent))
490 and then UI_Gt (Object_Access_Level (N),
491 Type_Access_Level (Typ))
492 and then not Accessibility_Checks_Suppressed (Param_Ent)
493 and then not Accessibility_Checks_Suppressed (Typ)
496 New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc);
499 Make_Integer_Literal (Loc, Type_Access_Level (Typ));
501 -- Raise Program_Error if the accessibility level of the the access
502 -- parameter is deeper than the level of the target access type.
505 Make_Raise_Program_Error (Loc,
508 Left_Opnd => Param_Level,
509 Right_Opnd => Type_Level),
510 Reason => PE_Accessibility_Check_Failed));
512 Analyze_And_Resolve (N);
514 end Apply_Accessibility_Check;
516 --------------------------------
517 -- Apply_Address_Clause_Check --
518 --------------------------------
520 procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is
521 AC : constant Node_Id := Address_Clause (E);
522 Loc : constant Source_Ptr := Sloc (AC);
523 Typ : constant Entity_Id := Etype (E);
524 Aexp : constant Node_Id := Expression (AC);
527 -- Address expression (not necessarily the same as Aexp, for example
528 -- when Aexp is a reference to a constant, in which case Expr gets
529 -- reset to reference the value expression of the constant.
531 Size_Warning_Output : Boolean := False;
532 -- If we output a size warning we set this True, to stop generating
533 -- what is likely to be an unuseful redundant alignment warning.
535 procedure Compile_Time_Bad_Alignment;
536 -- Post error warnings when alignment is known to be incompatible. Note
537 -- that we do not go as far as inserting a raise of Program_Error since
538 -- this is an erroneous case, and it may happen that we are lucky and an
539 -- underaligned address turns out to be OK after all. Also this warning
540 -- is suppressed if we already complained about the size.
542 --------------------------------
543 -- Compile_Time_Bad_Alignment --
544 --------------------------------
546 procedure Compile_Time_Bad_Alignment is
548 if not Size_Warning_Output
549 and then Address_Clause_Overlay_Warnings
552 ("?specified address for& may be inconsistent with alignment ",
555 ("\?program execution may be erroneous (RM 13.3(27))",
557 Set_Address_Warning_Posted (AC);
559 end Compile_Time_Bad_Alignment;
561 -- Start of processing for Apply_Address_Clause_Check
564 -- First obtain expression from address clause
566 Expr := Expression (AC);
568 -- The following loop digs for the real expression to use in the check
571 -- For constant, get constant expression
573 if Is_Entity_Name (Expr)
574 and then Ekind (Entity (Expr)) = E_Constant
576 Expr := Constant_Value (Entity (Expr));
578 -- For unchecked conversion, get result to convert
580 elsif Nkind (Expr) = N_Unchecked_Type_Conversion then
581 Expr := Expression (Expr);
583 -- For (common case) of To_Address call, get argument
585 elsif Nkind (Expr) = N_Function_Call
586 and then Is_Entity_Name (Name (Expr))
587 and then Is_RTE (Entity (Name (Expr)), RE_To_Address)
589 Expr := First (Parameter_Associations (Expr));
591 if Nkind (Expr) = N_Parameter_Association then
592 Expr := Explicit_Actual_Parameter (Expr);
595 -- We finally have the real expression
602 -- Output a warning if we have the situation of
604 -- for X'Address use Y'Address
606 -- and X and Y both have known object sizes, and Y is smaller than X
608 if Nkind (Expr) = N_Attribute_Reference
609 and then Attribute_Name (Expr) = Name_Address
610 and then Is_Entity_Name (Prefix (Expr))
613 Exp_Ent : constant Entity_Id := Entity (Prefix (Expr));
614 Obj_Size : Uint := No_Uint;
615 Exp_Size : Uint := No_Uint;
618 if Known_Esize (E) then
619 Obj_Size := Esize (E);
620 elsif Known_Esize (Etype (E)) then
621 Obj_Size := Esize (Etype (E));
624 if Known_Esize (Exp_Ent) then
625 Exp_Size := Esize (Exp_Ent);
626 elsif Known_Esize (Etype (Exp_Ent)) then
627 Exp_Size := Esize (Etype (Exp_Ent));
630 if Obj_Size /= No_Uint
631 and then Exp_Size /= No_Uint
632 and then Obj_Size > Exp_Size
633 and then not Has_Warnings_Off (E)
635 if Address_Clause_Overlay_Warnings then
637 ("?& overlays smaller object", Aexp, E);
639 ("\?program execution may be erroneous", Aexp, E);
640 Size_Warning_Output := True;
641 Set_Address_Warning_Posted (AC);
647 -- See if alignment check needed. Note that we never need a check if the
648 -- maximum alignment is one, since the check will always succeed.
650 -- Note: we do not check for checks suppressed here, since that check
651 -- was done in Sem_Ch13 when the address clause was processed. We are
652 -- only called if checks were not suppressed. The reason for this is
653 -- that we have to delay the call to Apply_Alignment_Check till freeze
654 -- time (so that all types etc are elaborated), but we have to check
655 -- the status of check suppressing at the point of the address clause.
658 or else not Check_Address_Alignment (AC)
659 or else Maximum_Alignment = 1
664 -- See if we know that Expr is a bad alignment at compile time
666 if Compile_Time_Known_Value (Expr)
667 and then (Known_Alignment (E) or else Known_Alignment (Typ))
670 AL : Uint := Alignment (Typ);
673 -- The object alignment might be more restrictive than the
676 if Known_Alignment (E) then
680 if Expr_Value (Expr) mod AL /= 0 then
681 Compile_Time_Bad_Alignment;
687 -- If the expression has the form X'Address, then we can find out if
688 -- the object X has an alignment that is compatible with the object E.
690 elsif Nkind (Expr) = N_Attribute_Reference
691 and then Attribute_Name (Expr) = Name_Address
694 AR : constant Alignment_Result :=
695 Has_Compatible_Alignment (E, Prefix (Expr));
697 if AR = Known_Compatible then
699 elsif AR = Known_Incompatible then
700 Compile_Time_Bad_Alignment;
705 -- Here we do not know if the value is acceptable. Stricly we don't have
706 -- to do anything, since if the alignment is bad, we have an erroneous
707 -- program. However we are allowed to check for erroneous conditions and
708 -- we decide to do this by default if the check is not suppressed.
710 -- However, don't do the check if elaboration code is unwanted
712 if Restriction_Active (No_Elaboration_Code) then
715 -- Generate a check to raise PE if alignment may be inappropriate
718 -- If the original expression is a non-static constant, use the
719 -- name of the constant itself rather than duplicating its
720 -- defining expression, which was extracted above.
722 -- Note: Expr is empty if the address-clause is applied to in-mode
723 -- actuals (allowed by 13.1(22)).
725 if not Present (Expr)
727 (Is_Entity_Name (Expression (AC))
728 and then Ekind (Entity (Expression (AC))) = E_Constant
729 and then Nkind (Parent (Entity (Expression (AC))))
730 = N_Object_Declaration)
732 Expr := New_Copy_Tree (Expression (AC));
734 Remove_Side_Effects (Expr);
737 Insert_After_And_Analyze (N,
738 Make_Raise_Program_Error (Loc,
745 (RTE (RE_Integer_Address), Expr),
747 Make_Attribute_Reference (Loc,
748 Prefix => New_Occurrence_Of (E, Loc),
749 Attribute_Name => Name_Alignment)),
750 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
751 Reason => PE_Misaligned_Address_Value),
752 Suppress => All_Checks);
757 -- If we have some missing run time component in configurable run time
758 -- mode then just skip the check (it is not required in any case).
760 when RE_Not_Available =>
762 end Apply_Address_Clause_Check;
764 -------------------------------------
765 -- Apply_Arithmetic_Overflow_Check --
766 -------------------------------------
768 -- This routine is called only if the type is an integer type, and
769 -- a software arithmetic overflow check must be performed for op
770 -- (add, subtract, multiply). The check is performed only if
771 -- Software_Overflow_Checking is enabled and Do_Overflow_Check
772 -- is set. In this case we expand the operation into a more complex
773 -- sequence of tests that ensures that overflow is properly caught.
775 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
776 Loc : constant Source_Ptr := Sloc (N);
777 Typ : constant Entity_Id := Etype (N);
778 Rtyp : constant Entity_Id := Root_Type (Typ);
779 Siz : constant Int := UI_To_Int (Esize (Rtyp));
780 Dsiz : constant Int := Siz * 2;
787 -- Skip this if overflow checks are done in back end, or the overflow
788 -- flag is not set anyway, or we are not doing code expansion.
789 -- Special case CLI target, where arithmetic overflow checks can be
790 -- performed for integer and long_integer
792 if Backend_Overflow_Checks_On_Target
793 or else (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
794 or else not Do_Overflow_Check (N)
795 or else not Expander_Active
800 -- Otherwise, we generate the full general code for front end overflow
801 -- detection, which works by doing arithmetic in a larger type:
807 -- Typ (Checktyp (x) op Checktyp (y));
809 -- where Typ is the type of the original expression, and Checktyp is
810 -- an integer type of sufficient length to hold the largest possible
813 -- In the case where check type exceeds the size of Long_Long_Integer,
814 -- we use a different approach, expanding to:
816 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
818 -- where xxx is Add, Multiply or Subtract as appropriate
820 -- Find check type if one exists
822 if Dsiz <= Standard_Integer_Size then
823 Ctyp := Standard_Integer;
825 elsif Dsiz <= Standard_Long_Long_Integer_Size then
826 Ctyp := Standard_Long_Long_Integer;
828 -- No check type exists, use runtime call
831 if Nkind (N) = N_Op_Add then
832 Cent := RE_Add_With_Ovflo_Check;
834 elsif Nkind (N) = N_Op_Multiply then
835 Cent := RE_Multiply_With_Ovflo_Check;
838 pragma Assert (Nkind (N) = N_Op_Subtract);
839 Cent := RE_Subtract_With_Ovflo_Check;
844 Make_Function_Call (Loc,
845 Name => New_Reference_To (RTE (Cent), Loc),
846 Parameter_Associations => New_List (
847 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
848 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
850 Analyze_And_Resolve (N, Typ);
854 -- If we fall through, we have the case where we do the arithmetic in
855 -- the next higher type and get the check by conversion. In these cases
856 -- Ctyp is set to the type to be used as the check type.
858 Opnod := Relocate_Node (N);
860 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
863 Set_Etype (Opnd, Ctyp);
864 Set_Analyzed (Opnd, True);
865 Set_Left_Opnd (Opnod, Opnd);
867 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
870 Set_Etype (Opnd, Ctyp);
871 Set_Analyzed (Opnd, True);
872 Set_Right_Opnd (Opnod, Opnd);
874 -- The type of the operation changes to the base type of the check type,
875 -- and we reset the overflow check indication, since clearly no overflow
876 -- is possible now that we are using a double length type. We also set
877 -- the Analyzed flag to avoid a recursive attempt to expand the node.
879 Set_Etype (Opnod, Base_Type (Ctyp));
880 Set_Do_Overflow_Check (Opnod, False);
881 Set_Analyzed (Opnod, True);
883 -- Now build the outer conversion
885 Opnd := OK_Convert_To (Typ, Opnod);
887 Set_Etype (Opnd, Typ);
889 -- In the discrete type case, we directly generate the range check for
890 -- the outer operand. This range check will implement the required
893 if Is_Discrete_Type (Typ) then
895 Generate_Range_Check (Expression (N), Typ, CE_Overflow_Check_Failed);
897 -- For other types, we enable overflow checking on the conversion,
898 -- after setting the node as analyzed to prevent recursive attempts
899 -- to expand the conversion node.
902 Set_Analyzed (Opnd, True);
903 Enable_Overflow_Check (Opnd);
908 when RE_Not_Available =>
910 end Apply_Arithmetic_Overflow_Check;
912 ----------------------------
913 -- Apply_Constraint_Check --
914 ----------------------------
916 procedure Apply_Constraint_Check
919 No_Sliding : Boolean := False)
921 Desig_Typ : Entity_Id;
924 if Inside_A_Generic then
927 elsif Is_Scalar_Type (Typ) then
928 Apply_Scalar_Range_Check (N, Typ);
930 elsif Is_Array_Type (Typ) then
932 -- A useful optimization: an aggregate with only an others clause
933 -- always has the right bounds.
935 if Nkind (N) = N_Aggregate
936 and then No (Expressions (N))
938 (First (Choices (First (Component_Associations (N)))))
944 if Is_Constrained (Typ) then
945 Apply_Length_Check (N, Typ);
948 Apply_Range_Check (N, Typ);
951 Apply_Range_Check (N, Typ);
954 elsif (Is_Record_Type (Typ)
955 or else Is_Private_Type (Typ))
956 and then Has_Discriminants (Base_Type (Typ))
957 and then Is_Constrained (Typ)
959 Apply_Discriminant_Check (N, Typ);
961 elsif Is_Access_Type (Typ) then
963 Desig_Typ := Designated_Type (Typ);
965 -- No checks necessary if expression statically null
967 if Known_Null (N) then
968 if Can_Never_Be_Null (Typ) then
969 Install_Null_Excluding_Check (N);
972 -- No sliding possible on access to arrays
974 elsif Is_Array_Type (Desig_Typ) then
975 if Is_Constrained (Desig_Typ) then
976 Apply_Length_Check (N, Typ);
979 Apply_Range_Check (N, Typ);
981 elsif Has_Discriminants (Base_Type (Desig_Typ))
982 and then Is_Constrained (Desig_Typ)
984 Apply_Discriminant_Check (N, Typ);
987 -- Apply the the 2005 Null_Excluding check. Note that we do not apply
988 -- this check if the constraint node is illegal, as shown by having
989 -- an error posted. This additional guard prevents cascaded errors
990 -- and compiler aborts on illegal programs involving Ada 2005 checks.
992 if Can_Never_Be_Null (Typ)
993 and then not Can_Never_Be_Null (Etype (N))
994 and then not Error_Posted (N)
996 Install_Null_Excluding_Check (N);
999 end Apply_Constraint_Check;
1001 ------------------------------
1002 -- Apply_Discriminant_Check --
1003 ------------------------------
1005 procedure Apply_Discriminant_Check
1008 Lhs : Node_Id := Empty)
1010 Loc : constant Source_Ptr := Sloc (N);
1011 Do_Access : constant Boolean := Is_Access_Type (Typ);
1012 S_Typ : Entity_Id := Etype (N);
1016 function Is_Aliased_Unconstrained_Component return Boolean;
1017 -- It is possible for an aliased component to have a nominal
1018 -- unconstrained subtype (through instantiation). If this is a
1019 -- discriminated component assigned in the expansion of an aggregate
1020 -- in an initialization, the check must be suppressed. This unusual
1021 -- situation requires a predicate of its own.
1023 ----------------------------------------
1024 -- Is_Aliased_Unconstrained_Component --
1025 ----------------------------------------
1027 function Is_Aliased_Unconstrained_Component return Boolean is
1032 if Nkind (Lhs) /= N_Selected_Component then
1035 Comp := Entity (Selector_Name (Lhs));
1036 Pref := Prefix (Lhs);
1039 if Ekind (Comp) /= E_Component
1040 or else not Is_Aliased (Comp)
1045 return not Comes_From_Source (Pref)
1046 and then In_Instance
1047 and then not Is_Constrained (Etype (Comp));
1048 end Is_Aliased_Unconstrained_Component;
1050 -- Start of processing for Apply_Discriminant_Check
1054 T_Typ := Designated_Type (Typ);
1059 -- Nothing to do if discriminant checks are suppressed or else no code
1060 -- is to be generated
1062 if not Expander_Active
1063 or else Discriminant_Checks_Suppressed (T_Typ)
1068 -- No discriminant checks necessary for an access when expression is
1069 -- statically Null. This is not only an optimization, it is fundamental
1070 -- because otherwise discriminant checks may be generated in init procs
1071 -- for types containing an access to a not-yet-frozen record, causing a
1072 -- deadly forward reference.
1074 -- Also, if the expression is of an access type whose designated type is
1075 -- incomplete, then the access value must be null and we suppress the
1078 if Known_Null (N) then
1081 elsif Is_Access_Type (S_Typ) then
1082 S_Typ := Designated_Type (S_Typ);
1084 if Ekind (S_Typ) = E_Incomplete_Type then
1089 -- If an assignment target is present, then we need to generate the
1090 -- actual subtype if the target is a parameter or aliased object with
1091 -- an unconstrained nominal subtype.
1093 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1094 -- subtype to the parameter and dereference cases, since other aliased
1095 -- objects are unconstrained (unless the nominal subtype is explicitly
1096 -- constrained). (But we also need to test for renamings???)
1099 and then (Present (Param_Entity (Lhs))
1100 or else (Ada_Version < Ada_05
1101 and then not Is_Constrained (T_Typ)
1102 and then Is_Aliased_View (Lhs)
1103 and then not Is_Aliased_Unconstrained_Component)
1104 or else (Ada_Version >= Ada_05
1105 and then not Is_Constrained (T_Typ)
1106 and then Nkind (Lhs) = N_Explicit_Dereference
1107 and then Nkind (Original_Node (Lhs)) /=
1110 T_Typ := Get_Actual_Subtype (Lhs);
1113 -- Nothing to do if the type is unconstrained (this is the case where
1114 -- the actual subtype in the RM sense of N is unconstrained and no check
1117 if not Is_Constrained (T_Typ) then
1120 -- Ada 2005: nothing to do if the type is one for which there is a
1121 -- partial view that is constrained.
1123 elsif Ada_Version >= Ada_05
1124 and then Has_Constrained_Partial_View (Base_Type (T_Typ))
1129 -- Nothing to do if the type is an Unchecked_Union
1131 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1135 -- Suppress checks if the subtypes are the same. the check must be
1136 -- preserved in an assignment to a formal, because the constraint is
1137 -- given by the actual.
1139 if Nkind (Original_Node (N)) /= N_Allocator
1141 or else not Is_Entity_Name (Lhs)
1142 or else No (Param_Entity (Lhs)))
1145 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1146 and then not Is_Aliased_View (Lhs)
1151 -- We can also eliminate checks on allocators with a subtype mark that
1152 -- coincides with the context type. The context type may be a subtype
1153 -- without a constraint (common case, a generic actual).
1155 elsif Nkind (Original_Node (N)) = N_Allocator
1156 and then Is_Entity_Name (Expression (Original_Node (N)))
1159 Alloc_Typ : constant Entity_Id :=
1160 Entity (Expression (Original_Node (N)));
1163 if Alloc_Typ = T_Typ
1164 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1165 and then Is_Entity_Name (
1166 Subtype_Indication (Parent (T_Typ)))
1167 and then Alloc_Typ = Base_Type (T_Typ))
1175 -- See if we have a case where the types are both constrained, and all
1176 -- the constraints are constants. In this case, we can do the check
1177 -- successfully at compile time.
1179 -- We skip this check for the case where the node is a rewritten`
1180 -- allocator, because it already carries the context subtype, and
1181 -- extracting the discriminants from the aggregate is messy.
1183 if Is_Constrained (S_Typ)
1184 and then Nkind (Original_Node (N)) /= N_Allocator
1194 -- S_Typ may not have discriminants in the case where it is a
1195 -- private type completed by a default discriminated type. In that
1196 -- case, we need to get the constraints from the underlying_type.
1197 -- If the underlying type is unconstrained (i.e. has no default
1198 -- discriminants) no check is needed.
1200 if Has_Discriminants (S_Typ) then
1201 Discr := First_Discriminant (S_Typ);
1202 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1205 Discr := First_Discriminant (Underlying_Type (S_Typ));
1208 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1214 -- A further optimization: if T_Typ is derived from S_Typ
1215 -- without imposing a constraint, no check is needed.
1217 if Nkind (Original_Node (Parent (T_Typ))) =
1218 N_Full_Type_Declaration
1221 Type_Def : constant Node_Id :=
1223 (Original_Node (Parent (T_Typ)));
1225 if Nkind (Type_Def) = N_Derived_Type_Definition
1226 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1227 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1235 DconT := First_Elmt (Discriminant_Constraint (T_Typ));
1237 while Present (Discr) loop
1238 ItemS := Node (DconS);
1239 ItemT := Node (DconT);
1241 -- For a discriminated component type constrained by the
1242 -- current instance of an enclosing type, there is no
1243 -- applicable discriminant check.
1245 if Nkind (ItemT) = N_Attribute_Reference
1246 and then Is_Access_Type (Etype (ItemT))
1247 and then Is_Entity_Name (Prefix (ItemT))
1248 and then Is_Type (Entity (Prefix (ItemT)))
1253 -- If the expressions for the discriminants are identical
1254 -- and it is side-effect free (for now just an entity),
1255 -- this may be a shared constraint, e.g. from a subtype
1256 -- without a constraint introduced as a generic actual.
1257 -- Examine other discriminants if any.
1260 and then Is_Entity_Name (ItemS)
1264 elsif not Is_OK_Static_Expression (ItemS)
1265 or else not Is_OK_Static_Expression (ItemT)
1269 elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
1270 if Do_Access then -- needs run-time check.
1273 Apply_Compile_Time_Constraint_Error
1274 (N, "incorrect value for discriminant&?",
1275 CE_Discriminant_Check_Failed, Ent => Discr);
1282 Next_Discriminant (Discr);
1291 -- Here we need a discriminant check. First build the expression
1292 -- for the comparisons of the discriminants:
1294 -- (n.disc1 /= typ.disc1) or else
1295 -- (n.disc2 /= typ.disc2) or else
1297 -- (n.discn /= typ.discn)
1299 Cond := Build_Discriminant_Checks (N, T_Typ);
1301 -- If Lhs is set and is a parameter, then the condition is
1302 -- guarded by: lhs'constrained and then (condition built above)
1304 if Present (Param_Entity (Lhs)) then
1308 Make_Attribute_Reference (Loc,
1309 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1310 Attribute_Name => Name_Constrained),
1311 Right_Opnd => Cond);
1315 Cond := Guard_Access (Cond, Loc, N);
1319 Make_Raise_Constraint_Error (Loc,
1321 Reason => CE_Discriminant_Check_Failed));
1322 end Apply_Discriminant_Check;
1324 ------------------------
1325 -- Apply_Divide_Check --
1326 ------------------------
1328 procedure Apply_Divide_Check (N : Node_Id) is
1329 Loc : constant Source_Ptr := Sloc (N);
1330 Typ : constant Entity_Id := Etype (N);
1331 Left : constant Node_Id := Left_Opnd (N);
1332 Right : constant Node_Id := Right_Opnd (N);
1342 pragma Warnings (Off, Lhi);
1343 -- Don't actually use this value
1347 and then not Backend_Divide_Checks_On_Target
1348 and then Check_Needed (Right, Division_Check)
1350 Determine_Range (Right, ROK, Rlo, Rhi);
1352 -- See if division by zero possible, and if so generate test. This
1353 -- part of the test is not controlled by the -gnato switch.
1355 if Do_Division_Check (N) then
1356 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1358 Make_Raise_Constraint_Error (Loc,
1361 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1362 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1363 Reason => CE_Divide_By_Zero));
1367 -- Test for extremely annoying case of xxx'First divided by -1
1369 if Do_Overflow_Check (N) then
1370 if Nkind (N) = N_Op_Divide
1371 and then Is_Signed_Integer_Type (Typ)
1373 Determine_Range (Left, LOK, Llo, Lhi);
1374 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1376 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1378 ((not LOK) or else (Llo = LLB))
1381 Make_Raise_Constraint_Error (Loc,
1387 Duplicate_Subexpr_Move_Checks (Left),
1388 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1392 Duplicate_Subexpr (Right),
1394 Make_Integer_Literal (Loc, -1))),
1395 Reason => CE_Overflow_Check_Failed));
1400 end Apply_Divide_Check;
1402 ----------------------------------
1403 -- Apply_Float_Conversion_Check --
1404 ----------------------------------
1406 -- Let F and I be the source and target types of the conversion. The RM
1407 -- specifies that a floating-point value X is rounded to the nearest
1408 -- integer, with halfway cases being rounded away from zero. The rounded
1409 -- value of X is checked against I'Range.
1411 -- The catch in the above paragraph is that there is no good way to know
1412 -- whether the round-to-integer operation resulted in overflow. A remedy is
1413 -- to perform a range check in the floating-point domain instead, however:
1415 -- (1) The bounds may not be known at compile time
1416 -- (2) The check must take into account rounding or truncation.
1417 -- (3) The range of type I may not be exactly representable in F.
1418 -- (4) For the rounding case, The end-points I'First - 0.5 and
1419 -- I'Last + 0.5 may or may not be in range, depending on the
1420 -- sign of I'First and I'Last.
1421 -- (5) X may be a NaN, which will fail any comparison
1423 -- The following steps correctly convert X with rounding:
1425 -- (1) If either I'First or I'Last is not known at compile time, use
1426 -- I'Base instead of I in the next three steps and perform a
1427 -- regular range check against I'Range after conversion.
1428 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1429 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1430 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1431 -- In other words, take one of the closest floating-point numbers
1432 -- (which is an integer value) to I'First, and see if it is in
1434 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1435 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1436 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1437 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1438 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1440 -- For the truncating case, replace steps (2) and (3) as follows:
1441 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1442 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1444 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1445 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1448 procedure Apply_Float_Conversion_Check
1450 Target_Typ : Entity_Id)
1452 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1453 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1454 Loc : constant Source_Ptr := Sloc (Ck_Node);
1455 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1456 Target_Base : constant Entity_Id :=
1457 Implementation_Base_Type (Target_Typ);
1459 Par : constant Node_Id := Parent (Ck_Node);
1460 pragma Assert (Nkind (Par) = N_Type_Conversion);
1461 -- Parent of check node, must be a type conversion
1463 Truncate : constant Boolean := Float_Truncate (Par);
1464 Max_Bound : constant Uint :=
1466 (Machine_Radix (Expr_Type),
1467 Machine_Mantissa (Expr_Type) - 1) - 1;
1469 -- Largest bound, so bound plus or minus half is a machine number of F
1471 Ifirst, Ilast : Uint;
1472 -- Bounds of integer type
1475 -- Bounds to check in floating-point domain
1477 Lo_OK, Hi_OK : Boolean;
1478 -- True iff Lo resp. Hi belongs to I'Range
1480 Lo_Chk, Hi_Chk : Node_Id;
1481 -- Expressions that are False iff check fails
1483 Reason : RT_Exception_Code;
1486 if not Compile_Time_Known_Value (LB)
1487 or not Compile_Time_Known_Value (HB)
1490 -- First check that the value falls in the range of the base type,
1491 -- to prevent overflow during conversion and then perform a
1492 -- regular range check against the (dynamic) bounds.
1494 pragma Assert (Target_Base /= Target_Typ);
1496 Temp : constant Entity_Id :=
1497 Make_Defining_Identifier (Loc,
1498 Chars => New_Internal_Name ('T'));
1501 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1502 Set_Etype (Temp, Target_Base);
1504 Insert_Action (Parent (Par),
1505 Make_Object_Declaration (Loc,
1506 Defining_Identifier => Temp,
1507 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1508 Expression => New_Copy_Tree (Par)),
1509 Suppress => All_Checks);
1512 Make_Raise_Constraint_Error (Loc,
1515 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1516 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1517 Reason => CE_Range_Check_Failed));
1518 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
1524 -- Get the bounds of the target type
1526 Ifirst := Expr_Value (LB);
1527 Ilast := Expr_Value (HB);
1529 -- Check against lower bound
1531 if Truncate and then Ifirst > 0 then
1532 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
1536 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
1539 elsif abs (Ifirst) < Max_Bound then
1540 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
1541 Lo_OK := (Ifirst > 0);
1544 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
1545 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
1550 -- Lo_Chk := (X >= Lo)
1552 Lo_Chk := Make_Op_Ge (Loc,
1553 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1554 Right_Opnd => Make_Real_Literal (Loc, Lo));
1557 -- Lo_Chk := (X > Lo)
1559 Lo_Chk := Make_Op_Gt (Loc,
1560 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1561 Right_Opnd => Make_Real_Literal (Loc, Lo));
1564 -- Check against higher bound
1566 if Truncate and then Ilast < 0 then
1567 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
1571 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
1574 elsif abs (Ilast) < Max_Bound then
1575 Hi := UR_From_Uint (Ilast) + Ureal_Half;
1576 Hi_OK := (Ilast < 0);
1578 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
1579 Hi_OK := (Hi <= UR_From_Uint (Ilast));
1584 -- Hi_Chk := (X <= Hi)
1586 Hi_Chk := Make_Op_Le (Loc,
1587 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1588 Right_Opnd => Make_Real_Literal (Loc, Hi));
1591 -- Hi_Chk := (X < Hi)
1593 Hi_Chk := Make_Op_Lt (Loc,
1594 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
1595 Right_Opnd => Make_Real_Literal (Loc, Hi));
1598 -- If the bounds of the target type are the same as those of the base
1599 -- type, the check is an overflow check as a range check is not
1600 -- performed in these cases.
1602 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
1603 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
1605 Reason := CE_Overflow_Check_Failed;
1607 Reason := CE_Range_Check_Failed;
1610 -- Raise CE if either conditions does not hold
1612 Insert_Action (Ck_Node,
1613 Make_Raise_Constraint_Error (Loc,
1614 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
1616 end Apply_Float_Conversion_Check;
1618 ------------------------
1619 -- Apply_Length_Check --
1620 ------------------------
1622 procedure Apply_Length_Check
1624 Target_Typ : Entity_Id;
1625 Source_Typ : Entity_Id := Empty)
1628 Apply_Selected_Length_Checks
1629 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1630 end Apply_Length_Check;
1632 -----------------------
1633 -- Apply_Range_Check --
1634 -----------------------
1636 procedure Apply_Range_Check
1638 Target_Typ : Entity_Id;
1639 Source_Typ : Entity_Id := Empty)
1642 Apply_Selected_Range_Checks
1643 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
1644 end Apply_Range_Check;
1646 ------------------------------
1647 -- Apply_Scalar_Range_Check --
1648 ------------------------------
1650 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
1651 -- off if it is already set on.
1653 procedure Apply_Scalar_Range_Check
1655 Target_Typ : Entity_Id;
1656 Source_Typ : Entity_Id := Empty;
1657 Fixed_Int : Boolean := False)
1659 Parnt : constant Node_Id := Parent (Expr);
1661 Arr : Node_Id := Empty; -- initialize to prevent warning
1662 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
1665 Is_Subscr_Ref : Boolean;
1666 -- Set true if Expr is a subscript
1668 Is_Unconstrained_Subscr_Ref : Boolean;
1669 -- Set true if Expr is a subscript of an unconstrained array. In this
1670 -- case we do not attempt to do an analysis of the value against the
1671 -- range of the subscript, since we don't know the actual subtype.
1674 -- Set to True if Expr should be regarded as a real value even though
1675 -- the type of Expr might be discrete.
1677 procedure Bad_Value;
1678 -- Procedure called if value is determined to be out of range
1684 procedure Bad_Value is
1686 Apply_Compile_Time_Constraint_Error
1687 (Expr, "value not in range of}?", CE_Range_Check_Failed,
1692 -- Start of processing for Apply_Scalar_Range_Check
1695 -- Return if check obviously not needed
1698 -- Not needed inside generic
1702 -- Not needed if previous error
1704 or else Target_Typ = Any_Type
1705 or else Nkind (Expr) = N_Error
1707 -- Not needed for non-scalar type
1709 or else not Is_Scalar_Type (Target_Typ)
1711 -- Not needed if we know node raises CE already
1713 or else Raises_Constraint_Error (Expr)
1718 -- Now, see if checks are suppressed
1721 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
1723 if Is_Subscr_Ref then
1724 Arr := Prefix (Parnt);
1725 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
1728 if not Do_Range_Check (Expr) then
1730 -- Subscript reference. Check for Index_Checks suppressed
1732 if Is_Subscr_Ref then
1734 -- Check array type and its base type
1736 if Index_Checks_Suppressed (Arr_Typ)
1737 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
1741 -- Check array itself if it is an entity name
1743 elsif Is_Entity_Name (Arr)
1744 and then Index_Checks_Suppressed (Entity (Arr))
1748 -- Check expression itself if it is an entity name
1750 elsif Is_Entity_Name (Expr)
1751 and then Index_Checks_Suppressed (Entity (Expr))
1756 -- All other cases, check for Range_Checks suppressed
1759 -- Check target type and its base type
1761 if Range_Checks_Suppressed (Target_Typ)
1762 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
1766 -- Check expression itself if it is an entity name
1768 elsif Is_Entity_Name (Expr)
1769 and then Range_Checks_Suppressed (Entity (Expr))
1773 -- If Expr is part of an assignment statement, then check left
1774 -- side of assignment if it is an entity name.
1776 elsif Nkind (Parnt) = N_Assignment_Statement
1777 and then Is_Entity_Name (Name (Parnt))
1778 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
1785 -- Do not set range checks if they are killed
1787 if Nkind (Expr) = N_Unchecked_Type_Conversion
1788 and then Kill_Range_Check (Expr)
1793 -- Do not set range checks for any values from System.Scalar_Values
1794 -- since the whole idea of such values is to avoid checking them!
1796 if Is_Entity_Name (Expr)
1797 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
1802 -- Now see if we need a check
1804 if No (Source_Typ) then
1805 S_Typ := Etype (Expr);
1807 S_Typ := Source_Typ;
1810 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
1814 Is_Unconstrained_Subscr_Ref :=
1815 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
1817 -- Always do a range check if the source type includes infinities and
1818 -- the target type does not include infinities. We do not do this if
1819 -- range checks are killed.
1821 if Is_Floating_Point_Type (S_Typ)
1822 and then Has_Infinities (S_Typ)
1823 and then not Has_Infinities (Target_Typ)
1825 Enable_Range_Check (Expr);
1828 -- Return if we know expression is definitely in the range of the target
1829 -- type as determined by Determine_Range. Right now we only do this for
1830 -- discrete types, and not fixed-point or floating-point types.
1832 -- The additional less-precise tests below catch these cases
1834 -- Note: skip this if we are given a source_typ, since the point of
1835 -- supplying a Source_Typ is to stop us looking at the expression.
1836 -- We could sharpen this test to be out parameters only ???
1838 if Is_Discrete_Type (Target_Typ)
1839 and then Is_Discrete_Type (Etype (Expr))
1840 and then not Is_Unconstrained_Subscr_Ref
1841 and then No (Source_Typ)
1844 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
1845 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
1850 if Compile_Time_Known_Value (Tlo)
1851 and then Compile_Time_Known_Value (Thi)
1854 Lov : constant Uint := Expr_Value (Tlo);
1855 Hiv : constant Uint := Expr_Value (Thi);
1858 -- If range is null, we for sure have a constraint error
1859 -- (we don't even need to look at the value involved,
1860 -- since all possible values will raise CE).
1867 -- Otherwise determine range of value
1869 Determine_Range (Expr, OK, Lo, Hi);
1873 -- If definitely in range, all OK
1875 if Lo >= Lov and then Hi <= Hiv then
1878 -- If definitely not in range, warn
1880 elsif Lov > Hi or else Hiv < Lo then
1884 -- Otherwise we don't know
1896 Is_Floating_Point_Type (S_Typ)
1897 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
1899 -- Check if we can determine at compile time whether Expr is in the
1900 -- range of the target type. Note that if S_Typ is within the bounds
1901 -- of Target_Typ then this must be the case. This check is meaningful
1902 -- only if this is not a conversion between integer and real types.
1904 if not Is_Unconstrained_Subscr_Ref
1906 Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
1908 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
1910 Is_In_Range (Expr, Target_Typ, Fixed_Int, Int_Real))
1914 elsif Is_Out_Of_Range (Expr, Target_Typ, Fixed_Int, Int_Real) then
1918 -- In the floating-point case, we only do range checks if the type is
1919 -- constrained. We definitely do NOT want range checks for unconstrained
1920 -- types, since we want to have infinities
1922 elsif Is_Floating_Point_Type (S_Typ) then
1923 if Is_Constrained (S_Typ) then
1924 Enable_Range_Check (Expr);
1927 -- For all other cases we enable a range check unconditionally
1930 Enable_Range_Check (Expr);
1933 end Apply_Scalar_Range_Check;
1935 ----------------------------------
1936 -- Apply_Selected_Length_Checks --
1937 ----------------------------------
1939 procedure Apply_Selected_Length_Checks
1941 Target_Typ : Entity_Id;
1942 Source_Typ : Entity_Id;
1943 Do_Static : Boolean)
1946 R_Result : Check_Result;
1949 Loc : constant Source_Ptr := Sloc (Ck_Node);
1950 Checks_On : constant Boolean :=
1951 (not Index_Checks_Suppressed (Target_Typ))
1953 (not Length_Checks_Suppressed (Target_Typ));
1956 if not Expander_Active then
1961 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
1963 for J in 1 .. 2 loop
1964 R_Cno := R_Result (J);
1965 exit when No (R_Cno);
1967 -- A length check may mention an Itype which is attached to a
1968 -- subsequent node. At the top level in a package this can cause
1969 -- an order-of-elaboration problem, so we make sure that the itype
1970 -- is referenced now.
1972 if Ekind (Current_Scope) = E_Package
1973 and then Is_Compilation_Unit (Current_Scope)
1975 Ensure_Defined (Target_Typ, Ck_Node);
1977 if Present (Source_Typ) then
1978 Ensure_Defined (Source_Typ, Ck_Node);
1980 elsif Is_Itype (Etype (Ck_Node)) then
1981 Ensure_Defined (Etype (Ck_Node), Ck_Node);
1985 -- If the item is a conditional raise of constraint error, then have
1986 -- a look at what check is being performed and ???
1988 if Nkind (R_Cno) = N_Raise_Constraint_Error
1989 and then Present (Condition (R_Cno))
1991 Cond := Condition (R_Cno);
1993 -- Case where node does not now have a dynamic check
1995 if not Has_Dynamic_Length_Check (Ck_Node) then
1997 -- If checks are on, just insert the check
2000 Insert_Action (Ck_Node, R_Cno);
2002 if not Do_Static then
2003 Set_Has_Dynamic_Length_Check (Ck_Node);
2006 -- If checks are off, then analyze the length check after
2007 -- temporarily attaching it to the tree in case the relevant
2008 -- condition can be evaluted at compile time. We still want a
2009 -- compile time warning in this case.
2012 Set_Parent (R_Cno, Ck_Node);
2017 -- Output a warning if the condition is known to be True
2019 if Is_Entity_Name (Cond)
2020 and then Entity (Cond) = Standard_True
2022 Apply_Compile_Time_Constraint_Error
2023 (Ck_Node, "wrong length for array of}?",
2024 CE_Length_Check_Failed,
2028 -- If we were only doing a static check, or if checks are not
2029 -- on, then we want to delete the check, since it is not needed.
2030 -- We do this by replacing the if statement by a null statement
2032 elsif Do_Static or else not Checks_On then
2033 Remove_Warning_Messages (R_Cno);
2034 Rewrite (R_Cno, Make_Null_Statement (Loc));
2038 Install_Static_Check (R_Cno, Loc);
2041 end Apply_Selected_Length_Checks;
2043 ---------------------------------
2044 -- Apply_Selected_Range_Checks --
2045 ---------------------------------
2047 procedure Apply_Selected_Range_Checks
2049 Target_Typ : Entity_Id;
2050 Source_Typ : Entity_Id;
2051 Do_Static : Boolean)
2054 R_Result : Check_Result;
2057 Loc : constant Source_Ptr := Sloc (Ck_Node);
2058 Checks_On : constant Boolean :=
2059 (not Index_Checks_Suppressed (Target_Typ))
2061 (not Range_Checks_Suppressed (Target_Typ));
2064 if not Expander_Active or else not Checks_On then
2069 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2071 for J in 1 .. 2 loop
2073 R_Cno := R_Result (J);
2074 exit when No (R_Cno);
2076 -- If the item is a conditional raise of constraint error, then have
2077 -- a look at what check is being performed and ???
2079 if Nkind (R_Cno) = N_Raise_Constraint_Error
2080 and then Present (Condition (R_Cno))
2082 Cond := Condition (R_Cno);
2084 if not Has_Dynamic_Range_Check (Ck_Node) then
2085 Insert_Action (Ck_Node, R_Cno);
2087 if not Do_Static then
2088 Set_Has_Dynamic_Range_Check (Ck_Node);
2092 -- Output a warning if the condition is known to be True
2094 if Is_Entity_Name (Cond)
2095 and then Entity (Cond) = Standard_True
2097 -- Since an N_Range is technically not an expression, we have
2098 -- to set one of the bounds to C_E and then just flag the
2099 -- N_Range. The warning message will point to the lower bound
2100 -- and complain about a range, which seems OK.
2102 if Nkind (Ck_Node) = N_Range then
2103 Apply_Compile_Time_Constraint_Error
2104 (Low_Bound (Ck_Node), "static range out of bounds of}?",
2105 CE_Range_Check_Failed,
2109 Set_Raises_Constraint_Error (Ck_Node);
2112 Apply_Compile_Time_Constraint_Error
2113 (Ck_Node, "static value out of range of}?",
2114 CE_Range_Check_Failed,
2119 -- If we were only doing a static check, or if checks are not
2120 -- on, then we want to delete the check, since it is not needed.
2121 -- We do this by replacing the if statement by a null statement
2123 elsif Do_Static or else not Checks_On then
2124 Remove_Warning_Messages (R_Cno);
2125 Rewrite (R_Cno, Make_Null_Statement (Loc));
2129 Install_Static_Check (R_Cno, Loc);
2132 end Apply_Selected_Range_Checks;
2134 -------------------------------
2135 -- Apply_Static_Length_Check --
2136 -------------------------------
2138 procedure Apply_Static_Length_Check
2140 Target_Typ : Entity_Id;
2141 Source_Typ : Entity_Id := Empty)
2144 Apply_Selected_Length_Checks
2145 (Expr, Target_Typ, Source_Typ, Do_Static => True);
2146 end Apply_Static_Length_Check;
2148 -------------------------------------
2149 -- Apply_Subscript_Validity_Checks --
2150 -------------------------------------
2152 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
2156 pragma Assert (Nkind (Expr) = N_Indexed_Component);
2158 -- Loop through subscripts
2160 Sub := First (Expressions (Expr));
2161 while Present (Sub) loop
2163 -- Check one subscript. Note that we do not worry about enumeration
2164 -- type with holes, since we will convert the value to a Pos value
2165 -- for the subscript, and that convert will do the necessary validity
2168 Ensure_Valid (Sub, Holes_OK => True);
2170 -- Move to next subscript
2174 end Apply_Subscript_Validity_Checks;
2176 ----------------------------------
2177 -- Apply_Type_Conversion_Checks --
2178 ----------------------------------
2180 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
2181 Target_Type : constant Entity_Id := Etype (N);
2182 Target_Base : constant Entity_Id := Base_Type (Target_Type);
2183 Expr : constant Node_Id := Expression (N);
2184 Expr_Type : constant Entity_Id := Etype (Expr);
2187 if Inside_A_Generic then
2190 -- Skip these checks if serious errors detected, there are some nasty
2191 -- situations of incomplete trees that blow things up.
2193 elsif Serious_Errors_Detected > 0 then
2196 -- Scalar type conversions of the form Target_Type (Expr) require a
2197 -- range check if we cannot be sure that Expr is in the base type of
2198 -- Target_Typ and also that Expr is in the range of Target_Typ. These
2199 -- are not quite the same condition from an implementation point of
2200 -- view, but clearly the second includes the first.
2202 elsif Is_Scalar_Type (Target_Type) then
2204 Conv_OK : constant Boolean := Conversion_OK (N);
2205 -- If the Conversion_OK flag on the type conversion is set and no
2206 -- floating point type is involved in the type conversion then
2207 -- fixed point values must be read as integral values.
2209 Float_To_Int : constant Boolean :=
2210 Is_Floating_Point_Type (Expr_Type)
2211 and then Is_Integer_Type (Target_Type);
2214 if not Overflow_Checks_Suppressed (Target_Base)
2215 and then not In_Subrange_Of (Expr_Type, Target_Base, Conv_OK)
2216 and then not Float_To_Int
2218 Activate_Overflow_Check (N);
2221 if not Range_Checks_Suppressed (Target_Type)
2222 and then not Range_Checks_Suppressed (Expr_Type)
2224 if Float_To_Int then
2225 Apply_Float_Conversion_Check (Expr, Target_Type);
2227 Apply_Scalar_Range_Check
2228 (Expr, Target_Type, Fixed_Int => Conv_OK);
2233 elsif Comes_From_Source (N)
2234 and then Is_Record_Type (Target_Type)
2235 and then Is_Derived_Type (Target_Type)
2236 and then not Is_Tagged_Type (Target_Type)
2237 and then not Is_Constrained (Target_Type)
2238 and then Present (Stored_Constraint (Target_Type))
2240 -- An unconstrained derived type may have inherited discriminant
2241 -- Build an actual discriminant constraint list using the stored
2242 -- constraint, to verify that the expression of the parent type
2243 -- satisfies the constraints imposed by the (unconstrained!)
2244 -- derived type. This applies to value conversions, not to view
2245 -- conversions of tagged types.
2248 Loc : constant Source_Ptr := Sloc (N);
2250 Constraint : Elmt_Id;
2251 Discr_Value : Node_Id;
2254 New_Constraints : constant Elist_Id := New_Elmt_List;
2255 Old_Constraints : constant Elist_Id :=
2256 Discriminant_Constraint (Expr_Type);
2259 Constraint := First_Elmt (Stored_Constraint (Target_Type));
2260 while Present (Constraint) loop
2261 Discr_Value := Node (Constraint);
2263 if Is_Entity_Name (Discr_Value)
2264 and then Ekind (Entity (Discr_Value)) = E_Discriminant
2266 Discr := Corresponding_Discriminant (Entity (Discr_Value));
2269 and then Scope (Discr) = Base_Type (Expr_Type)
2271 -- Parent is constrained by new discriminant. Obtain
2272 -- Value of original discriminant in expression. If the
2273 -- new discriminant has been used to constrain more than
2274 -- one of the stored discriminants, this will provide the
2275 -- required consistency check.
2278 Make_Selected_Component (Loc,
2280 Duplicate_Subexpr_No_Checks
2281 (Expr, Name_Req => True),
2283 Make_Identifier (Loc, Chars (Discr))),
2287 -- Discriminant of more remote ancestor ???
2292 -- Derived type definition has an explicit value for this
2293 -- stored discriminant.
2297 (Duplicate_Subexpr_No_Checks (Discr_Value),
2301 Next_Elmt (Constraint);
2304 -- Use the unconstrained expression type to retrieve the
2305 -- discriminants of the parent, and apply momentarily the
2306 -- discriminant constraint synthesized above.
2308 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
2309 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
2310 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
2313 Make_Raise_Constraint_Error (Loc,
2315 Reason => CE_Discriminant_Check_Failed));
2318 -- For arrays, conversions are applied during expansion, to take into
2319 -- accounts changes of representation. The checks become range checks on
2320 -- the base type or length checks on the subtype, depending on whether
2321 -- the target type is unconstrained or constrained.
2326 end Apply_Type_Conversion_Checks;
2328 ----------------------------------------------
2329 -- Apply_Universal_Integer_Attribute_Checks --
2330 ----------------------------------------------
2332 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
2333 Loc : constant Source_Ptr := Sloc (N);
2334 Typ : constant Entity_Id := Etype (N);
2337 if Inside_A_Generic then
2340 -- Nothing to do if checks are suppressed
2342 elsif Range_Checks_Suppressed (Typ)
2343 and then Overflow_Checks_Suppressed (Typ)
2347 -- Nothing to do if the attribute does not come from source. The
2348 -- internal attributes we generate of this type do not need checks,
2349 -- and furthermore the attempt to check them causes some circular
2350 -- elaboration orders when dealing with packed types.
2352 elsif not Comes_From_Source (N) then
2355 -- If the prefix is a selected component that depends on a discriminant
2356 -- the check may improperly expose a discriminant instead of using
2357 -- the bounds of the object itself. Set the type of the attribute to
2358 -- the base type of the context, so that a check will be imposed when
2359 -- needed (e.g. if the node appears as an index).
2361 elsif Nkind (Prefix (N)) = N_Selected_Component
2362 and then Ekind (Typ) = E_Signed_Integer_Subtype
2363 and then Depends_On_Discriminant (Scalar_Range (Typ))
2365 Set_Etype (N, Base_Type (Typ));
2367 -- Otherwise, replace the attribute node with a type conversion node
2368 -- whose expression is the attribute, retyped to universal integer, and
2369 -- whose subtype mark is the target type. The call to analyze this
2370 -- conversion will set range and overflow checks as required for proper
2371 -- detection of an out of range value.
2374 Set_Etype (N, Universal_Integer);
2375 Set_Analyzed (N, True);
2378 Make_Type_Conversion (Loc,
2379 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
2380 Expression => Relocate_Node (N)));
2382 Analyze_And_Resolve (N, Typ);
2385 end Apply_Universal_Integer_Attribute_Checks;
2387 -------------------------------
2388 -- Build_Discriminant_Checks --
2389 -------------------------------
2391 function Build_Discriminant_Checks
2393 T_Typ : Entity_Id) return Node_Id
2395 Loc : constant Source_Ptr := Sloc (N);
2398 Disc_Ent : Entity_Id;
2402 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
2404 ----------------------------------
2405 -- Aggregate_Discriminant_Value --
2406 ----------------------------------
2408 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
2412 -- The aggregate has been normalized with named associations. We use
2413 -- the Chars field to locate the discriminant to take into account
2414 -- discriminants in derived types, which carry the same name as those
2417 Assoc := First (Component_Associations (N));
2418 while Present (Assoc) loop
2419 if Chars (First (Choices (Assoc))) = Chars (Disc) then
2420 return Expression (Assoc);
2426 -- Discriminant must have been found in the loop above
2428 raise Program_Error;
2429 end Aggregate_Discriminant_Val;
2431 -- Start of processing for Build_Discriminant_Checks
2434 -- Loop through discriminants evolving the condition
2437 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
2439 -- For a fully private type, use the discriminants of the parent type
2441 if Is_Private_Type (T_Typ)
2442 and then No (Full_View (T_Typ))
2444 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
2446 Disc_Ent := First_Discriminant (T_Typ);
2449 while Present (Disc) loop
2450 Dval := Node (Disc);
2452 if Nkind (Dval) = N_Identifier
2453 and then Ekind (Entity (Dval)) = E_Discriminant
2455 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
2457 Dval := Duplicate_Subexpr_No_Checks (Dval);
2460 -- If we have an Unchecked_Union node, we can infer the discriminants
2463 if Is_Unchecked_Union (Base_Type (T_Typ)) then
2465 Get_Discriminant_Value (
2466 First_Discriminant (T_Typ),
2468 Stored_Constraint (T_Typ)));
2470 elsif Nkind (N) = N_Aggregate then
2472 Duplicate_Subexpr_No_Checks
2473 (Aggregate_Discriminant_Val (Disc_Ent));
2477 Make_Selected_Component (Loc,
2479 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
2481 Make_Identifier (Loc, Chars (Disc_Ent)));
2483 Set_Is_In_Discriminant_Check (Dref);
2486 Evolve_Or_Else (Cond,
2489 Right_Opnd => Dval));
2492 Next_Discriminant (Disc_Ent);
2496 end Build_Discriminant_Checks;
2502 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
2510 -- Always check if not simple entity
2512 if Nkind (Nod) not in N_Has_Entity
2513 or else not Comes_From_Source (Nod)
2518 -- Look up tree for short circuit
2525 -- Done if out of subexpression (note that we allow generated stuff
2526 -- such as itype declarations in this context, to keep the loop going
2527 -- since we may well have generated such stuff in complex situations.
2528 -- Also done if no parent (probably an error condition, but no point
2529 -- in behaving nasty if we find it!)
2532 or else (K not in N_Subexpr and then Comes_From_Source (P))
2536 -- Or/Or Else case, where test is part of the right operand, or is
2537 -- part of one of the actions associated with the right operand, and
2538 -- the left operand is an equality test.
2540 elsif K = N_Op_Or then
2541 exit when N = Right_Opnd (P)
2542 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2544 elsif K = N_Or_Else then
2545 exit when (N = Right_Opnd (P)
2548 and then List_Containing (N) = Actions (P)))
2549 and then Nkind (Left_Opnd (P)) = N_Op_Eq;
2551 -- Similar test for the And/And then case, where the left operand
2552 -- is an inequality test.
2554 elsif K = N_Op_And then
2555 exit when N = Right_Opnd (P)
2556 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2558 elsif K = N_And_Then then
2559 exit when (N = Right_Opnd (P)
2562 and then List_Containing (N) = Actions (P)))
2563 and then Nkind (Left_Opnd (P)) = N_Op_Ne;
2569 -- If we fall through the loop, then we have a conditional with an
2570 -- appropriate test as its left operand. So test further.
2573 R := Right_Opnd (L);
2576 -- Left operand of test must match original variable
2578 if Nkind (L) not in N_Has_Entity
2579 or else Entity (L) /= Entity (Nod)
2584 -- Right operand of test must be key value (zero or null)
2587 when Access_Check =>
2588 if not Known_Null (R) then
2592 when Division_Check =>
2593 if not Compile_Time_Known_Value (R)
2594 or else Expr_Value (R) /= Uint_0
2600 raise Program_Error;
2603 -- Here we have the optimizable case, warn if not short-circuited
2605 if K = N_Op_And or else K = N_Op_Or then
2607 when Access_Check =>
2609 ("Constraint_Error may be raised (access check)?",
2611 when Division_Check =>
2613 ("Constraint_Error may be raised (zero divide)?",
2617 raise Program_Error;
2620 if K = N_Op_And then
2621 Error_Msg_N ("use `AND THEN` instead of AND?", P);
2623 Error_Msg_N ("use `OR ELSE` instead of OR?", P);
2626 -- If not short-circuited, we need the ckeck
2630 -- If short-circuited, we can omit the check
2637 -----------------------------------
2638 -- Check_Valid_Lvalue_Subscripts --
2639 -----------------------------------
2641 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
2643 -- Skip this if range checks are suppressed
2645 if Range_Checks_Suppressed (Etype (Expr)) then
2648 -- Only do this check for expressions that come from source. We assume
2649 -- that expander generated assignments explicitly include any necessary
2650 -- checks. Note that this is not just an optimization, it avoids
2651 -- infinite recursions!
2653 elsif not Comes_From_Source (Expr) then
2656 -- For a selected component, check the prefix
2658 elsif Nkind (Expr) = N_Selected_Component then
2659 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2662 -- Case of indexed component
2664 elsif Nkind (Expr) = N_Indexed_Component then
2665 Apply_Subscript_Validity_Checks (Expr);
2667 -- Prefix may itself be or contain an indexed component, and these
2668 -- subscripts need checking as well.
2670 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
2672 end Check_Valid_Lvalue_Subscripts;
2674 ----------------------------------
2675 -- Null_Exclusion_Static_Checks --
2676 ----------------------------------
2678 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
2679 Error_Node : Node_Id;
2681 Has_Null : constant Boolean := Has_Null_Exclusion (N);
2682 K : constant Node_Kind := Nkind (N);
2687 (K = N_Component_Declaration
2688 or else K = N_Discriminant_Specification
2689 or else K = N_Function_Specification
2690 or else K = N_Object_Declaration
2691 or else K = N_Parameter_Specification);
2693 if K = N_Function_Specification then
2694 Typ := Etype (Defining_Entity (N));
2696 Typ := Etype (Defining_Identifier (N));
2700 when N_Component_Declaration =>
2701 if Present (Access_Definition (Component_Definition (N))) then
2702 Error_Node := Component_Definition (N);
2704 Error_Node := Subtype_Indication (Component_Definition (N));
2707 when N_Discriminant_Specification =>
2708 Error_Node := Discriminant_Type (N);
2710 when N_Function_Specification =>
2711 Error_Node := Result_Definition (N);
2713 when N_Object_Declaration =>
2714 Error_Node := Object_Definition (N);
2716 when N_Parameter_Specification =>
2717 Error_Node := Parameter_Type (N);
2720 raise Program_Error;
2725 -- Enforce legality rule 3.10 (13): A null exclusion can only be
2726 -- applied to an access [sub]type.
2728 if not Is_Access_Type (Typ) then
2730 ("`NOT NULL` allowed only for an access type", Error_Node);
2732 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
2733 -- be applied to a [sub]type that does not exclude null already.
2735 elsif Can_Never_Be_Null (Typ)
2737 -- No need to check itypes that have a null exclusion because
2738 -- they are already examined at their point of creation.
2740 and then not Is_Itype (Typ)
2743 ("`NOT NULL` not allowed (& already excludes null)",
2748 -- Check that null-excluding objects are always initialized, except for
2749 -- deferred constants, for which the expression will appear in the full
2752 if K = N_Object_Declaration
2753 and then No (Expression (N))
2754 and then not Constant_Present (N)
2755 and then not No_Initialization (N)
2757 -- Add an expression that assigns null. This node is needed by
2758 -- Apply_Compile_Time_Constraint_Error, which will replace this with
2759 -- a Constraint_Error node.
2761 Set_Expression (N, Make_Null (Sloc (N)));
2762 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
2764 Apply_Compile_Time_Constraint_Error
2765 (N => Expression (N),
2766 Msg => "(Ada 2005) null-excluding objects must be initialized?",
2767 Reason => CE_Null_Not_Allowed);
2770 -- Check that a null-excluding component, formal or object is not being
2771 -- assigned a null value. Otherwise generate a warning message and
2772 -- replace Expression (N) by an N_Constraint_Error node.
2774 if K /= N_Function_Specification then
2775 Expr := Expression (N);
2777 if Present (Expr) and then Known_Null (Expr) then
2779 when N_Component_Declaration |
2780 N_Discriminant_Specification =>
2781 Apply_Compile_Time_Constraint_Error
2783 Msg => "(Ada 2005) null not allowed " &
2784 "in null-excluding components?",
2785 Reason => CE_Null_Not_Allowed);
2787 when N_Object_Declaration =>
2788 Apply_Compile_Time_Constraint_Error
2790 Msg => "(Ada 2005) null not allowed " &
2791 "in null-excluding objects?",
2792 Reason => CE_Null_Not_Allowed);
2794 when N_Parameter_Specification =>
2795 Apply_Compile_Time_Constraint_Error
2797 Msg => "(Ada 2005) null not allowed " &
2798 "in null-excluding formals?",
2799 Reason => CE_Null_Not_Allowed);
2806 end Null_Exclusion_Static_Checks;
2808 ----------------------------------
2809 -- Conditional_Statements_Begin --
2810 ----------------------------------
2812 procedure Conditional_Statements_Begin is
2814 Saved_Checks_TOS := Saved_Checks_TOS + 1;
2816 -- If stack overflows, kill all checks, that way we know to simply reset
2817 -- the number of saved checks to zero on return. This should never occur
2820 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2823 -- In the normal case, we just make a new stack entry saving the current
2824 -- number of saved checks for a later restore.
2827 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
2829 if Debug_Flag_CC then
2830 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
2834 end Conditional_Statements_Begin;
2836 --------------------------------
2837 -- Conditional_Statements_End --
2838 --------------------------------
2840 procedure Conditional_Statements_End is
2842 pragma Assert (Saved_Checks_TOS > 0);
2844 -- If the saved checks stack overflowed, then we killed all checks, so
2845 -- setting the number of saved checks back to zero is correct. This
2846 -- should never occur in practice.
2848 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
2849 Num_Saved_Checks := 0;
2851 -- In the normal case, restore the number of saved checks from the top
2855 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
2856 if Debug_Flag_CC then
2857 w ("Conditional_Statements_End: Num_Saved_Checks = ",
2862 Saved_Checks_TOS := Saved_Checks_TOS - 1;
2863 end Conditional_Statements_End;
2865 ---------------------
2866 -- Determine_Range --
2867 ---------------------
2869 Cache_Size : constant := 2 ** 10;
2870 type Cache_Index is range 0 .. Cache_Size - 1;
2871 -- Determine size of below cache (power of 2 is more efficient!)
2873 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
2874 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
2875 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
2876 -- The above arrays are used to implement a small direct cache for
2877 -- Determine_Range calls. Because of the way Determine_Range recursively
2878 -- traces subexpressions, and because overflow checking calls the routine
2879 -- on the way up the tree, a quadratic behavior can otherwise be
2880 -- encountered in large expressions. The cache entry for node N is stored
2881 -- in the (N mod Cache_Size) entry, and can be validated by checking the
2882 -- actual node value stored there.
2884 procedure Determine_Range
2890 Typ : constant Entity_Id := Etype (N);
2894 -- Lo and Hi bounds of left operand
2898 -- Lo and Hi bounds of right (or only) operand
2901 -- Temp variable used to hold a bound node
2904 -- High bound of base type of expression
2908 -- Refined values for low and high bounds, after tightening
2911 -- Used in lower level calls to indicate if call succeeded
2913 Cindex : Cache_Index;
2914 -- Used to search cache
2916 function OK_Operands return Boolean;
2917 -- Used for binary operators. Determines the ranges of the left and
2918 -- right operands, and if they are both OK, returns True, and puts
2919 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left
2925 function OK_Operands return Boolean is
2927 Determine_Range (Left_Opnd (N), OK1, Lo_Left, Hi_Left);
2933 Determine_Range (Right_Opnd (N), OK1, Lo_Right, Hi_Right);
2937 -- Start of processing for Determine_Range
2940 -- Prevent junk warnings by initializing range variables
2947 -- If the type is not discrete, or is undefined, then we can't do
2948 -- anything about determining the range.
2950 if No (Typ) or else not Is_Discrete_Type (Typ)
2951 or else Error_Posted (N)
2957 -- For all other cases, we can determine the range
2961 -- If value is compile time known, then the possible range is the one
2962 -- value that we know this expression definitely has!
2964 if Compile_Time_Known_Value (N) then
2965 Lo := Expr_Value (N);
2970 -- Return if already in the cache
2972 Cindex := Cache_Index (N mod Cache_Size);
2974 if Determine_Range_Cache_N (Cindex) = N then
2975 Lo := Determine_Range_Cache_Lo (Cindex);
2976 Hi := Determine_Range_Cache_Hi (Cindex);
2980 -- Otherwise, start by finding the bounds of the type of the expression,
2981 -- the value cannot be outside this range (if it is, then we have an
2982 -- overflow situation, which is a separate check, we are talking here
2983 -- only about the expression value).
2985 -- We use the actual bound unless it is dynamic, in which case use the
2986 -- corresponding base type bound if possible. If we can't get a bound
2987 -- then we figure we can't determine the range (a peculiar case, that
2988 -- perhaps cannot happen, but there is no point in bombing in this
2989 -- optimization circuit.
2991 -- First the low bound
2993 Bound := Type_Low_Bound (Typ);
2995 if Compile_Time_Known_Value (Bound) then
2996 Lo := Expr_Value (Bound);
2998 elsif Compile_Time_Known_Value (Type_Low_Bound (Base_Type (Typ))) then
2999 Lo := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
3006 -- Now the high bound
3008 Bound := Type_High_Bound (Typ);
3010 -- We need the high bound of the base type later on, and this should
3011 -- always be compile time known. Again, it is not clear that this
3012 -- can ever be false, but no point in bombing.
3014 if Compile_Time_Known_Value (Type_High_Bound (Base_Type (Typ))) then
3015 Hbound := Expr_Value (Type_High_Bound (Base_Type (Typ)));
3023 -- If we have a static subtype, then that may have a tighter bound so
3024 -- use the upper bound of the subtype instead in this case.
3026 if Compile_Time_Known_Value (Bound) then
3027 Hi := Expr_Value (Bound);
3030 -- We may be able to refine this value in certain situations. If any
3031 -- refinement is possible, then Lor and Hir are set to possibly tighter
3032 -- bounds, and OK1 is set to True.
3036 -- For unary plus, result is limited by range of operand
3039 Determine_Range (Right_Opnd (N), OK1, Lor, Hir);
3041 -- For unary minus, determine range of operand, and negate it
3044 Determine_Range (Right_Opnd (N), OK1, Lo_Right, Hi_Right);
3051 -- For binary addition, get range of each operand and do the
3052 -- addition to get the result range.
3056 Lor := Lo_Left + Lo_Right;
3057 Hir := Hi_Left + Hi_Right;
3060 -- Division is tricky. The only case we consider is where the right
3061 -- operand is a positive constant, and in this case we simply divide
3062 -- the bounds of the left operand
3066 if Lo_Right = Hi_Right
3067 and then Lo_Right > 0
3069 Lor := Lo_Left / Lo_Right;
3070 Hir := Hi_Left / Lo_Right;
3077 -- For binary subtraction, get range of each operand and do the worst
3078 -- case subtraction to get the result range.
3080 when N_Op_Subtract =>
3082 Lor := Lo_Left - Hi_Right;
3083 Hir := Hi_Left - Lo_Right;
3086 -- For MOD, if right operand is a positive constant, then result must
3087 -- be in the allowable range of mod results.
3091 if Lo_Right = Hi_Right
3092 and then Lo_Right /= 0
3094 if Lo_Right > 0 then
3096 Hir := Lo_Right - 1;
3098 else -- Lo_Right < 0
3099 Lor := Lo_Right + 1;
3108 -- For REM, if right operand is a positive constant, then result must
3109 -- be in the allowable range of mod results.
3113 if Lo_Right = Hi_Right
3114 and then Lo_Right /= 0
3117 Dval : constant Uint := (abs Lo_Right) - 1;
3120 -- The sign of the result depends on the sign of the
3121 -- dividend (but not on the sign of the divisor, hence
3122 -- the abs operation above).
3142 -- Attribute reference cases
3144 when N_Attribute_Reference =>
3145 case Attribute_Name (N) is
3147 -- For Pos/Val attributes, we can refine the range using the
3148 -- possible range of values of the attribute expression
3150 when Name_Pos | Name_Val =>
3151 Determine_Range (First (Expressions (N)), OK1, Lor, Hir);
3153 -- For Length attribute, use the bounds of the corresponding
3154 -- index type to refine the range.
3158 Atyp : Entity_Id := Etype (Prefix (N));
3166 if Is_Access_Type (Atyp) then
3167 Atyp := Designated_Type (Atyp);
3170 -- For string literal, we know exact value
3172 if Ekind (Atyp) = E_String_Literal_Subtype then
3174 Lo := String_Literal_Length (Atyp);
3175 Hi := String_Literal_Length (Atyp);
3179 -- Otherwise check for expression given
3181 if No (Expressions (N)) then
3185 UI_To_Int (Expr_Value (First (Expressions (N))));
3188 Indx := First_Index (Atyp);
3189 for J in 2 .. Inum loop
3190 Indx := Next_Index (Indx);
3194 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU);
3198 (Type_High_Bound (Etype (Indx)), OK1, UL, UU);
3202 -- The maximum value for Length is the biggest
3203 -- possible gap between the values of the bounds.
3204 -- But of course, this value cannot be negative.
3206 Hir := UI_Max (Uint_0, UU - LL);
3208 -- For constrained arrays, the minimum value for
3209 -- Length is taken from the actual value of the
3210 -- bounds, since the index will be exactly of
3213 if Is_Constrained (Atyp) then
3214 Lor := UI_Max (Uint_0, UL - LU);
3216 -- For an unconstrained array, the minimum value
3217 -- for length is always zero.
3226 -- No special handling for other attributes
3227 -- Probably more opportunities exist here ???
3234 -- For type conversion from one discrete type to another, we can
3235 -- refine the range using the converted value.
3237 when N_Type_Conversion =>
3238 Determine_Range (Expression (N), OK1, Lor, Hir);
3240 -- Nothing special to do for all other expression kinds
3248 -- At this stage, if OK1 is true, then we know that the actual
3249 -- result of the computed expression is in the range Lor .. Hir.
3250 -- We can use this to restrict the possible range of results.
3254 -- If the refined value of the low bound is greater than the
3255 -- type high bound, then reset it to the more restrictive
3256 -- value. However, we do NOT do this for the case of a modular
3257 -- type where the possible upper bound on the value is above the
3258 -- base type high bound, because that means the result could wrap.
3261 and then not (Is_Modular_Integer_Type (Typ)
3262 and then Hir > Hbound)
3267 -- Similarly, if the refined value of the high bound is less
3268 -- than the value so far, then reset it to the more restrictive
3269 -- value. Again, we do not do this if the refined low bound is
3270 -- negative for a modular type, since this would wrap.
3273 and then not (Is_Modular_Integer_Type (Typ)
3274 and then Lor < Uint_0)
3280 -- Set cache entry for future call and we are all done
3282 Determine_Range_Cache_N (Cindex) := N;
3283 Determine_Range_Cache_Lo (Cindex) := Lo;
3284 Determine_Range_Cache_Hi (Cindex) := Hi;
3287 -- If any exception occurs, it means that we have some bug in the compiler
3288 -- possibly triggered by a previous error, or by some unforseen peculiar
3289 -- occurrence. However, this is only an optimization attempt, so there is
3290 -- really no point in crashing the compiler. Instead we just decide, too
3291 -- bad, we can't figure out a range in this case after all.
3296 -- Debug flag K disables this behavior (useful for debugging)
3298 if Debug_Flag_K then
3306 end Determine_Range;
3308 ------------------------------------
3309 -- Discriminant_Checks_Suppressed --
3310 ------------------------------------
3312 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
3315 if Is_Unchecked_Union (E) then
3317 elsif Checks_May_Be_Suppressed (E) then
3318 return Is_Check_Suppressed (E, Discriminant_Check);
3322 return Scope_Suppress (Discriminant_Check);
3323 end Discriminant_Checks_Suppressed;
3325 --------------------------------
3326 -- Division_Checks_Suppressed --
3327 --------------------------------
3329 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
3331 if Present (E) and then Checks_May_Be_Suppressed (E) then
3332 return Is_Check_Suppressed (E, Division_Check);
3334 return Scope_Suppress (Division_Check);
3336 end Division_Checks_Suppressed;
3338 -----------------------------------
3339 -- Elaboration_Checks_Suppressed --
3340 -----------------------------------
3342 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
3344 -- The complication in this routine is that if we are in the dynamic
3345 -- model of elaboration, we also check All_Checks, since All_Checks
3346 -- does not set Elaboration_Check explicitly.
3349 if Kill_Elaboration_Checks (E) then
3352 elsif Checks_May_Be_Suppressed (E) then
3353 if Is_Check_Suppressed (E, Elaboration_Check) then
3355 elsif Dynamic_Elaboration_Checks then
3356 return Is_Check_Suppressed (E, All_Checks);
3363 if Scope_Suppress (Elaboration_Check) then
3365 elsif Dynamic_Elaboration_Checks then
3366 return Scope_Suppress (All_Checks);
3370 end Elaboration_Checks_Suppressed;
3372 ---------------------------
3373 -- Enable_Overflow_Check --
3374 ---------------------------
3376 procedure Enable_Overflow_Check (N : Node_Id) is
3377 Typ : constant Entity_Id := Base_Type (Etype (N));
3386 if Debug_Flag_CC then
3387 w ("Enable_Overflow_Check for node ", Int (N));
3388 Write_Str (" Source location = ");
3393 -- Nothing to do if the range of the result is known OK. We skip this
3394 -- for conversions, since the caller already did the check, and in any
3395 -- case the condition for deleting the check for a type conversion is
3398 if Nkind (N) /= N_Type_Conversion then
3399 Determine_Range (N, OK, Lo, Hi);
3401 -- Note in the test below that we assume that the range is not OK
3402 -- if a bound of the range is equal to that of the type. That's not
3403 -- quite accurate but we do this for the following reasons:
3405 -- a) The way that Determine_Range works, it will typically report
3406 -- the bounds of the value as being equal to the bounds of the
3407 -- type, because it either can't tell anything more precise, or
3408 -- does not think it is worth the effort to be more precise.
3410 -- b) It is very unusual to have a situation in which this would
3411 -- generate an unnecessary overflow check (an example would be
3412 -- a subtype with a range 0 .. Integer'Last - 1 to which the
3413 -- literal value one is added).
3415 -- c) The alternative is a lot of special casing in this routine
3416 -- which would partially duplicate Determine_Range processing.
3419 and then Lo > Expr_Value (Type_Low_Bound (Typ))
3420 and then Hi < Expr_Value (Type_High_Bound (Typ))
3422 if Debug_Flag_CC then
3423 w ("No overflow check required");
3430 -- If not in optimizing mode, set flag and we are done. We are also done
3431 -- (and just set the flag) if the type is not a discrete type, since it
3432 -- is not worth the effort to eliminate checks for other than discrete
3433 -- types. In addition, we take this same path if we have stored the
3434 -- maximum number of checks possible already (a very unlikely situation,
3435 -- but we do not want to blow up!)
3437 if Optimization_Level = 0
3438 or else not Is_Discrete_Type (Etype (N))
3439 or else Num_Saved_Checks = Saved_Checks'Last
3441 Activate_Overflow_Check (N);
3443 if Debug_Flag_CC then
3444 w ("Optimization off");
3450 -- Otherwise evaluate and check the expression
3455 Target_Type => Empty,
3461 if Debug_Flag_CC then
3462 w ("Called Find_Check");
3466 w (" Check_Num = ", Chk);
3467 w (" Ent = ", Int (Ent));
3468 Write_Str (" Ofs = ");
3473 -- If check is not of form to optimize, then set flag and we are done
3476 Activate_Overflow_Check (N);
3480 -- If check is already performed, then return without setting flag
3483 if Debug_Flag_CC then
3484 w ("Check suppressed!");
3490 -- Here we will make a new entry for the new check
3492 Activate_Overflow_Check (N);
3493 Num_Saved_Checks := Num_Saved_Checks + 1;
3494 Saved_Checks (Num_Saved_Checks) :=
3499 Target_Type => Empty);
3501 if Debug_Flag_CC then
3502 w ("Make new entry, check number = ", Num_Saved_Checks);
3503 w (" Entity = ", Int (Ent));
3504 Write_Str (" Offset = ");
3506 w (" Check_Type = O");
3507 w (" Target_Type = Empty");
3510 -- If we get an exception, then something went wrong, probably because of
3511 -- an error in the structure of the tree due to an incorrect program. Or it
3512 -- may be a bug in the optimization circuit. In either case the safest
3513 -- thing is simply to set the check flag unconditionally.
3517 Activate_Overflow_Check (N);
3519 if Debug_Flag_CC then
3520 w (" exception occurred, overflow flag set");
3524 end Enable_Overflow_Check;
3526 ------------------------
3527 -- Enable_Range_Check --
3528 ------------------------
3530 procedure Enable_Range_Check (N : Node_Id) is
3539 -- Return if unchecked type conversion with range check killed. In this
3540 -- case we never set the flag (that's what Kill_Range_Check is about!)
3542 if Nkind (N) = N_Unchecked_Type_Conversion
3543 and then Kill_Range_Check (N)
3548 -- Check for various cases where we should suppress the range check
3550 -- No check if range checks suppressed for type of node
3552 if Present (Etype (N))
3553 and then Range_Checks_Suppressed (Etype (N))
3557 -- No check if node is an entity name, and range checks are suppressed
3558 -- for this entity, or for the type of this entity.
3560 elsif Is_Entity_Name (N)
3561 and then (Range_Checks_Suppressed (Entity (N))
3562 or else Range_Checks_Suppressed (Etype (Entity (N))))
3566 -- No checks if index of array, and index checks are suppressed for
3567 -- the array object or the type of the array.
3569 elsif Nkind (Parent (N)) = N_Indexed_Component then
3571 Pref : constant Node_Id := Prefix (Parent (N));
3573 if Is_Entity_Name (Pref)
3574 and then Index_Checks_Suppressed (Entity (Pref))
3577 elsif Index_Checks_Suppressed (Etype (Pref)) then
3583 -- Debug trace output
3585 if Debug_Flag_CC then
3586 w ("Enable_Range_Check for node ", Int (N));
3587 Write_Str (" Source location = ");
3592 -- If not in optimizing mode, set flag and we are done. We are also done
3593 -- (and just set the flag) if the type is not a discrete type, since it
3594 -- is not worth the effort to eliminate checks for other than discrete
3595 -- types. In addition, we take this same path if we have stored the
3596 -- maximum number of checks possible already (a very unlikely situation,
3597 -- but we do not want to blow up!)
3599 if Optimization_Level = 0
3600 or else No (Etype (N))
3601 or else not Is_Discrete_Type (Etype (N))
3602 or else Num_Saved_Checks = Saved_Checks'Last
3604 Activate_Range_Check (N);
3606 if Debug_Flag_CC then
3607 w ("Optimization off");
3613 -- Otherwise find out the target type
3617 -- For assignment, use left side subtype
3619 if Nkind (P) = N_Assignment_Statement
3620 and then Expression (P) = N
3622 Ttyp := Etype (Name (P));
3624 -- For indexed component, use subscript subtype
3626 elsif Nkind (P) = N_Indexed_Component then
3633 Atyp := Etype (Prefix (P));
3635 if Is_Access_Type (Atyp) then
3636 Atyp := Designated_Type (Atyp);
3638 -- If the prefix is an access to an unconstrained array,
3639 -- perform check unconditionally: it depends on the bounds of
3640 -- an object and we cannot currently recognize whether the test
3641 -- may be redundant.
3643 if not Is_Constrained (Atyp) then
3644 Activate_Range_Check (N);
3648 -- Ditto if the prefix is an explicit dereference whose designated
3649 -- type is unconstrained.
3651 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
3652 and then not Is_Constrained (Atyp)
3654 Activate_Range_Check (N);
3658 Indx := First_Index (Atyp);
3659 Subs := First (Expressions (P));
3662 Ttyp := Etype (Indx);
3671 -- For now, ignore all other cases, they are not so interesting
3674 if Debug_Flag_CC then
3675 w (" target type not found, flag set");
3678 Activate_Range_Check (N);
3682 -- Evaluate and check the expression
3687 Target_Type => Ttyp,
3693 if Debug_Flag_CC then
3694 w ("Called Find_Check");
3695 w ("Target_Typ = ", Int (Ttyp));
3699 w (" Check_Num = ", Chk);
3700 w (" Ent = ", Int (Ent));
3701 Write_Str (" Ofs = ");
3706 -- If check is not of form to optimize, then set flag and we are done
3709 if Debug_Flag_CC then
3710 w (" expression not of optimizable type, flag set");
3713 Activate_Range_Check (N);
3717 -- If check is already performed, then return without setting flag
3720 if Debug_Flag_CC then
3721 w ("Check suppressed!");
3727 -- Here we will make a new entry for the new check
3729 Activate_Range_Check (N);
3730 Num_Saved_Checks := Num_Saved_Checks + 1;
3731 Saved_Checks (Num_Saved_Checks) :=
3736 Target_Type => Ttyp);
3738 if Debug_Flag_CC then
3739 w ("Make new entry, check number = ", Num_Saved_Checks);
3740 w (" Entity = ", Int (Ent));
3741 Write_Str (" Offset = ");
3743 w (" Check_Type = R");
3744 w (" Target_Type = ", Int (Ttyp));
3745 pg (Union_Id (Ttyp));
3748 -- If we get an exception, then something went wrong, probably because of
3749 -- an error in the structure of the tree due to an incorrect program. Or
3750 -- it may be a bug in the optimization circuit. In either case the safest
3751 -- thing is simply to set the check flag unconditionally.
3755 Activate_Range_Check (N);
3757 if Debug_Flag_CC then
3758 w (" exception occurred, range flag set");
3762 end Enable_Range_Check;
3768 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
3769 Typ : constant Entity_Id := Etype (Expr);
3772 -- Ignore call if we are not doing any validity checking
3774 if not Validity_Checks_On then
3777 -- Ignore call if range or validity checks suppressed on entity or type
3779 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
3782 -- No check required if expression is from the expander, we assume the
3783 -- expander will generate whatever checks are needed. Note that this is
3784 -- not just an optimization, it avoids infinite recursions!
3786 -- Unchecked conversions must be checked, unless they are initialized
3787 -- scalar values, as in a component assignment in an init proc.
3789 -- In addition, we force a check if Force_Validity_Checks is set
3791 elsif not Comes_From_Source (Expr)
3792 and then not Force_Validity_Checks
3793 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
3794 or else Kill_Range_Check (Expr))
3798 -- No check required if expression is known to have valid value
3800 elsif Expr_Known_Valid (Expr) then
3803 -- Ignore case of enumeration with holes where the flag is set not to
3804 -- worry about holes, since no special validity check is needed
3806 elsif Is_Enumeration_Type (Typ)
3807 and then Has_Non_Standard_Rep (Typ)
3812 -- No check required on the left-hand side of an assignment
3814 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
3815 and then Expr = Name (Parent (Expr))
3819 -- No check on a univeral real constant. The context will eventually
3820 -- convert it to a machine number for some target type, or report an
3823 elsif Nkind (Expr) = N_Real_Literal
3824 and then Etype (Expr) = Universal_Real
3828 -- If the expression denotes a component of a packed boolean arrray,
3829 -- no possible check applies. We ignore the old ACATS chestnuts that
3830 -- involve Boolean range True..True.
3832 -- Note: validity checks are generated for expressions that yield a
3833 -- scalar type, when it is possible to create a value that is outside of
3834 -- the type. If this is a one-bit boolean no such value exists. This is
3835 -- an optimization, and it also prevents compiler blowing up during the
3836 -- elaboration of improperly expanded packed array references.
3838 elsif Nkind (Expr) = N_Indexed_Component
3839 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
3840 and then Root_Type (Etype (Expr)) = Standard_Boolean
3844 -- An annoying special case. If this is an out parameter of a scalar
3845 -- type, then the value is not going to be accessed, therefore it is
3846 -- inappropriate to do any validity check at the call site.
3849 -- Only need to worry about scalar types
3851 if Is_Scalar_Type (Typ) then
3861 -- Find actual argument (which may be a parameter association)
3862 -- and the parent of the actual argument (the call statement)
3867 if Nkind (P) = N_Parameter_Association then
3872 -- Only need to worry if we are argument of a procedure call
3873 -- since functions don't have out parameters. If this is an
3874 -- indirect or dispatching call, get signature from the
3877 if Nkind (P) = N_Procedure_Call_Statement then
3878 L := Parameter_Associations (P);
3880 if Is_Entity_Name (Name (P)) then
3881 E := Entity (Name (P));
3883 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
3884 E := Etype (Name (P));
3887 -- Only need to worry if there are indeed actuals, and if
3888 -- this could be a procedure call, otherwise we cannot get a
3889 -- match (either we are not an argument, or the mode of the
3890 -- formal is not OUT). This test also filters out the
3893 if Is_Non_Empty_List (L)
3894 and then Is_Subprogram (E)
3896 -- This is the loop through parameters, looking for an
3897 -- OUT parameter for which we are the argument.
3899 F := First_Formal (E);
3901 while Present (F) loop
3902 if Ekind (F) = E_Out_Parameter and then A = N then
3915 -- If we fall through, a validity check is required
3917 Insert_Valid_Check (Expr);
3919 if Is_Entity_Name (Expr)
3920 and then Safe_To_Capture_Value (Expr, Entity (Expr))
3922 Set_Is_Known_Valid (Entity (Expr));
3926 ----------------------
3927 -- Expr_Known_Valid --
3928 ----------------------
3930 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
3931 Typ : constant Entity_Id := Etype (Expr);
3934 -- Non-scalar types are always considered valid, since they never give
3935 -- rise to the issues of erroneous or bounded error behavior that are
3936 -- the concern. In formal reference manual terms the notion of validity
3937 -- only applies to scalar types. Note that even when packed arrays are
3938 -- represented using modular types, they are still arrays semantically,
3939 -- so they are also always valid (in particular, the unused bits can be
3940 -- random rubbish without affecting the validity of the array value).
3942 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
3945 -- If no validity checking, then everything is considered valid
3947 elsif not Validity_Checks_On then
3950 -- Floating-point types are considered valid unless floating-point
3951 -- validity checks have been specifically turned on.
3953 elsif Is_Floating_Point_Type (Typ)
3954 and then not Validity_Check_Floating_Point
3958 -- If the expression is the value of an object that is known to be
3959 -- valid, then clearly the expression value itself is valid.
3961 elsif Is_Entity_Name (Expr)
3962 and then Is_Known_Valid (Entity (Expr))
3966 -- References to discriminants are always considered valid. The value
3967 -- of a discriminant gets checked when the object is built. Within the
3968 -- record, we consider it valid, and it is important to do so, since
3969 -- otherwise we can try to generate bogus validity checks which
3970 -- reference discriminants out of scope. Discriminants of concurrent
3971 -- types are excluded for the same reason.
3973 elsif Is_Entity_Name (Expr)
3974 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
3978 -- If the type is one for which all values are known valid, then we are
3979 -- sure that the value is valid except in the slightly odd case where
3980 -- the expression is a reference to a variable whose size has been
3981 -- explicitly set to a value greater than the object size.
3983 elsif Is_Known_Valid (Typ) then
3984 if Is_Entity_Name (Expr)
3985 and then Ekind (Entity (Expr)) = E_Variable
3986 and then Esize (Entity (Expr)) > Esize (Typ)
3993 -- Integer and character literals always have valid values, where
3994 -- appropriate these will be range checked in any case.
3996 elsif Nkind (Expr) = N_Integer_Literal
3998 Nkind (Expr) = N_Character_Literal
4002 -- If we have a type conversion or a qualification of a known valid
4003 -- value, then the result will always be valid.
4005 elsif Nkind (Expr) = N_Type_Conversion
4007 Nkind (Expr) = N_Qualified_Expression
4009 return Expr_Known_Valid (Expression (Expr));
4011 -- The result of any operator is always considered valid, since we
4012 -- assume the necessary checks are done by the operator. For operators
4013 -- on floating-point operations, we must also check when the operation
4014 -- is the right-hand side of an assignment, or is an actual in a call.
4016 elsif Nkind (Expr) in N_Op then
4017 if Is_Floating_Point_Type (Typ)
4018 and then Validity_Check_Floating_Point
4020 (Nkind (Parent (Expr)) = N_Assignment_Statement
4021 or else Nkind (Parent (Expr)) = N_Function_Call
4022 or else Nkind (Parent (Expr)) = N_Parameter_Association)
4029 -- The result of a membership test is always valid, since it is true or
4030 -- false, there are no other possibilities.
4032 elsif Nkind (Expr) in N_Membership_Test then
4035 -- For all other cases, we do not know the expression is valid
4040 end Expr_Known_Valid;
4046 procedure Find_Check
4048 Check_Type : Character;
4049 Target_Type : Entity_Id;
4050 Entry_OK : out Boolean;
4051 Check_Num : out Nat;
4052 Ent : out Entity_Id;
4055 function Within_Range_Of
4056 (Target_Type : Entity_Id;
4057 Check_Type : Entity_Id) return Boolean;
4058 -- Given a requirement for checking a range against Target_Type, and
4059 -- and a range Check_Type against which a check has already been made,
4060 -- determines if the check against check type is sufficient to ensure
4061 -- that no check against Target_Type is required.
4063 ---------------------
4064 -- Within_Range_Of --
4065 ---------------------
4067 function Within_Range_Of
4068 (Target_Type : Entity_Id;
4069 Check_Type : Entity_Id) return Boolean
4072 if Target_Type = Check_Type then
4077 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
4078 Thi : constant Node_Id := Type_High_Bound (Target_Type);
4079 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
4080 Chi : constant Node_Id := Type_High_Bound (Check_Type);
4084 or else (Compile_Time_Known_Value (Tlo)
4086 Compile_Time_Known_Value (Clo)
4088 Expr_Value (Clo) >= Expr_Value (Tlo)))
4091 or else (Compile_Time_Known_Value (Thi)
4093 Compile_Time_Known_Value (Chi)
4095 Expr_Value (Chi) <= Expr_Value (Clo)))
4103 end Within_Range_Of;
4105 -- Start of processing for Find_Check
4108 -- Establish default, to avoid warnings from GCC
4112 -- Case of expression is simple entity reference
4114 if Is_Entity_Name (Expr) then
4115 Ent := Entity (Expr);
4118 -- Case of expression is entity + known constant
4120 elsif Nkind (Expr) = N_Op_Add
4121 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4122 and then Is_Entity_Name (Left_Opnd (Expr))
4124 Ent := Entity (Left_Opnd (Expr));
4125 Ofs := Expr_Value (Right_Opnd (Expr));
4127 -- Case of expression is entity - known constant
4129 elsif Nkind (Expr) = N_Op_Subtract
4130 and then Compile_Time_Known_Value (Right_Opnd (Expr))
4131 and then Is_Entity_Name (Left_Opnd (Expr))
4133 Ent := Entity (Left_Opnd (Expr));
4134 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
4136 -- Any other expression is not of the right form
4145 -- Come here with expression of appropriate form, check if entity is an
4146 -- appropriate one for our purposes.
4148 if (Ekind (Ent) = E_Variable
4149 or else Is_Constant_Object (Ent))
4150 and then not Is_Library_Level_Entity (Ent)
4158 -- See if there is matching check already
4160 for J in reverse 1 .. Num_Saved_Checks loop
4162 SC : Saved_Check renames Saved_Checks (J);
4165 if SC.Killed = False
4166 and then SC.Entity = Ent
4167 and then SC.Offset = Ofs
4168 and then SC.Check_Type = Check_Type
4169 and then Within_Range_Of (Target_Type, SC.Target_Type)
4177 -- If we fall through entry was not found
4183 ---------------------------------
4184 -- Generate_Discriminant_Check --
4185 ---------------------------------
4187 -- Note: the code for this procedure is derived from the
4188 -- Emit_Discriminant_Check Routine in trans.c.
4190 procedure Generate_Discriminant_Check (N : Node_Id) is
4191 Loc : constant Source_Ptr := Sloc (N);
4192 Pref : constant Node_Id := Prefix (N);
4193 Sel : constant Node_Id := Selector_Name (N);
4195 Orig_Comp : constant Entity_Id :=
4196 Original_Record_Component (Entity (Sel));
4197 -- The original component to be checked
4199 Discr_Fct : constant Entity_Id :=
4200 Discriminant_Checking_Func (Orig_Comp);
4201 -- The discriminant checking function
4204 -- One discriminant to be checked in the type
4206 Real_Discr : Entity_Id;
4207 -- Actual discriminant in the call
4209 Pref_Type : Entity_Id;
4210 -- Type of relevant prefix (ignoring private/access stuff)
4213 -- List of arguments for function call
4216 -- Keep track of the formal corresponding to the actual we build for
4217 -- each discriminant, in order to be able to perform the necessary type
4221 -- Selected component reference for checking function argument
4224 Pref_Type := Etype (Pref);
4226 -- Force evaluation of the prefix, so that it does not get evaluated
4227 -- twice (once for the check, once for the actual reference). Such a
4228 -- double evaluation is always a potential source of inefficiency,
4229 -- and is functionally incorrect in the volatile case, or when the
4230 -- prefix may have side-effects. An entity or a component of an
4231 -- entity requires no evaluation.
4233 if Is_Entity_Name (Pref) then
4234 if Treat_As_Volatile (Entity (Pref)) then
4235 Force_Evaluation (Pref, Name_Req => True);
4238 elsif Treat_As_Volatile (Etype (Pref)) then
4239 Force_Evaluation (Pref, Name_Req => True);
4241 elsif Nkind (Pref) = N_Selected_Component
4242 and then Is_Entity_Name (Prefix (Pref))
4247 Force_Evaluation (Pref, Name_Req => True);
4250 -- For a tagged type, use the scope of the original component to
4251 -- obtain the type, because ???
4253 if Is_Tagged_Type (Scope (Orig_Comp)) then
4254 Pref_Type := Scope (Orig_Comp);
4256 -- For an untagged derived type, use the discriminants of the parent
4257 -- which have been renamed in the derivation, possibly by a one-to-many
4258 -- discriminant constraint. For non-tagged type, initially get the Etype
4262 if Is_Derived_Type (Pref_Type)
4263 and then Number_Discriminants (Pref_Type) /=
4264 Number_Discriminants (Etype (Base_Type (Pref_Type)))
4266 Pref_Type := Etype (Base_Type (Pref_Type));
4270 -- We definitely should have a checking function, This routine should
4271 -- not be called if no discriminant checking function is present.
4273 pragma Assert (Present (Discr_Fct));
4275 -- Create the list of the actual parameters for the call. This list
4276 -- is the list of the discriminant fields of the record expression to
4277 -- be discriminant checked.
4280 Formal := First_Formal (Discr_Fct);
4281 Discr := First_Discriminant (Pref_Type);
4282 while Present (Discr) loop
4284 -- If we have a corresponding discriminant field, and a parent
4285 -- subtype is present, then we want to use the corresponding
4286 -- discriminant since this is the one with the useful value.
4288 if Present (Corresponding_Discriminant (Discr))
4289 and then Ekind (Pref_Type) = E_Record_Type
4290 and then Present (Parent_Subtype (Pref_Type))
4292 Real_Discr := Corresponding_Discriminant (Discr);
4294 Real_Discr := Discr;
4297 -- Construct the reference to the discriminant
4300 Make_Selected_Component (Loc,
4302 Unchecked_Convert_To (Pref_Type,
4303 Duplicate_Subexpr (Pref)),
4304 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
4306 -- Manually analyze and resolve this selected component. We really
4307 -- want it just as it appears above, and do not want the expander
4308 -- playing discriminal games etc with this reference. Then we append
4309 -- the argument to the list we are gathering.
4311 Set_Etype (Scomp, Etype (Real_Discr));
4312 Set_Analyzed (Scomp, True);
4313 Append_To (Args, Convert_To (Etype (Formal), Scomp));
4315 Next_Formal_With_Extras (Formal);
4316 Next_Discriminant (Discr);
4319 -- Now build and insert the call
4322 Make_Raise_Constraint_Error (Loc,
4324 Make_Function_Call (Loc,
4325 Name => New_Occurrence_Of (Discr_Fct, Loc),
4326 Parameter_Associations => Args),
4327 Reason => CE_Discriminant_Check_Failed));
4328 end Generate_Discriminant_Check;
4330 ---------------------------
4331 -- Generate_Index_Checks --
4332 ---------------------------
4334 procedure Generate_Index_Checks (N : Node_Id) is
4335 Loc : constant Source_Ptr := Sloc (N);
4336 A : constant Node_Id := Prefix (N);
4342 -- Ignore call if index checks suppressed for array object or type
4344 if (Is_Entity_Name (A) and then Index_Checks_Suppressed (Entity (A)))
4345 or else Index_Checks_Suppressed (Etype (A))
4350 -- Generate the checks
4352 Sub := First (Expressions (N));
4354 while Present (Sub) loop
4355 if Do_Range_Check (Sub) then
4356 Set_Do_Range_Check (Sub, False);
4358 -- Force evaluation except for the case of a simple name of a
4359 -- non-volatile entity.
4361 if not Is_Entity_Name (Sub)
4362 or else Treat_As_Volatile (Entity (Sub))
4364 Force_Evaluation (Sub);
4367 -- Generate a raise of constraint error with the appropriate
4368 -- reason and a condition of the form:
4370 -- Base_Type(Sub) not in array'range (subscript)
4372 -- Note that the reason we generate the conversion to the base
4373 -- type here is that we definitely want the range check to take
4374 -- place, even if it looks like the subtype is OK. Optimization
4375 -- considerations that allow us to omit the check have already
4376 -- been taken into account in the setting of the Do_Range_Check
4382 Num := New_List (Make_Integer_Literal (Loc, Ind));
4386 Make_Raise_Constraint_Error (Loc,
4390 Convert_To (Base_Type (Etype (Sub)),
4391 Duplicate_Subexpr_Move_Checks (Sub)),
4393 Make_Attribute_Reference (Loc,
4395 Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
4396 Attribute_Name => Name_Range,
4397 Expressions => Num)),
4398 Reason => CE_Index_Check_Failed));
4404 end Generate_Index_Checks;
4406 --------------------------
4407 -- Generate_Range_Check --
4408 --------------------------
4410 procedure Generate_Range_Check
4412 Target_Type : Entity_Id;
4413 Reason : RT_Exception_Code)
4415 Loc : constant Source_Ptr := Sloc (N);
4416 Source_Type : constant Entity_Id := Etype (N);
4417 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
4418 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
4421 -- First special case, if the source type is already within the range
4422 -- of the target type, then no check is needed (probably we should have
4423 -- stopped Do_Range_Check from being set in the first place, but better
4424 -- late than later in preventing junk code!
4426 -- We do NOT apply this if the source node is a literal, since in this
4427 -- case the literal has already been labeled as having the subtype of
4430 if In_Subrange_Of (Source_Type, Target_Type)
4432 (Nkind (N) = N_Integer_Literal
4434 Nkind (N) = N_Real_Literal
4436 Nkind (N) = N_Character_Literal
4439 and then Ekind (Entity (N)) = E_Enumeration_Literal))
4444 -- We need a check, so force evaluation of the node, so that it does
4445 -- not get evaluated twice (once for the check, once for the actual
4446 -- reference). Such a double evaluation is always a potential source
4447 -- of inefficiency, and is functionally incorrect in the volatile case.
4449 if not Is_Entity_Name (N)
4450 or else Treat_As_Volatile (Entity (N))
4452 Force_Evaluation (N);
4455 -- The easiest case is when Source_Base_Type and Target_Base_Type are
4456 -- the same since in this case we can simply do a direct check of the
4457 -- value of N against the bounds of Target_Type.
4459 -- [constraint_error when N not in Target_Type]
4461 -- Note: this is by far the most common case, for example all cases of
4462 -- checks on the RHS of assignments are in this category, but not all
4463 -- cases are like this. Notably conversions can involve two types.
4465 if Source_Base_Type = Target_Base_Type then
4467 Make_Raise_Constraint_Error (Loc,
4470 Left_Opnd => Duplicate_Subexpr (N),
4471 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4474 -- Next test for the case where the target type is within the bounds
4475 -- of the base type of the source type, since in this case we can
4476 -- simply convert these bounds to the base type of T to do the test.
4478 -- [constraint_error when N not in
4479 -- Source_Base_Type (Target_Type'First)
4481 -- Source_Base_Type(Target_Type'Last))]
4483 -- The conversions will always work and need no check
4485 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
4487 Make_Raise_Constraint_Error (Loc,
4490 Left_Opnd => Duplicate_Subexpr (N),
4495 Convert_To (Source_Base_Type,
4496 Make_Attribute_Reference (Loc,
4498 New_Occurrence_Of (Target_Type, Loc),
4499 Attribute_Name => Name_First)),
4502 Convert_To (Source_Base_Type,
4503 Make_Attribute_Reference (Loc,
4505 New_Occurrence_Of (Target_Type, Loc),
4506 Attribute_Name => Name_Last)))),
4509 -- Note that at this stage we now that the Target_Base_Type is not in
4510 -- the range of the Source_Base_Type (since even the Target_Type itself
4511 -- is not in this range). It could still be the case that Source_Type is
4512 -- in range of the target base type since we have not checked that case.
4514 -- If that is the case, we can freely convert the source to the target,
4515 -- and then test the target result against the bounds.
4517 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
4519 -- We make a temporary to hold the value of the converted value
4520 -- (converted to the base type), and then we will do the test against
4523 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
4524 -- [constraint_error when Tnn not in Target_Type]
4526 -- Then the conversion itself is replaced by an occurrence of Tnn
4529 Tnn : constant Entity_Id :=
4530 Make_Defining_Identifier (Loc,
4531 Chars => New_Internal_Name ('T'));
4534 Insert_Actions (N, New_List (
4535 Make_Object_Declaration (Loc,
4536 Defining_Identifier => Tnn,
4537 Object_Definition =>
4538 New_Occurrence_Of (Target_Base_Type, Loc),
4539 Constant_Present => True,
4541 Make_Type_Conversion (Loc,
4542 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
4543 Expression => Duplicate_Subexpr (N))),
4545 Make_Raise_Constraint_Error (Loc,
4548 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4549 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
4551 Reason => Reason)));
4553 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4555 -- Set the type of N, because the declaration for Tnn might not
4556 -- be analyzed yet, as is the case if N appears within a record
4557 -- declaration, as a discriminant constraint or expression.
4559 Set_Etype (N, Target_Base_Type);
4562 -- At this stage, we know that we have two scalar types, which are
4563 -- directly convertible, and where neither scalar type has a base
4564 -- range that is in the range of the other scalar type.
4566 -- The only way this can happen is with a signed and unsigned type.
4567 -- So test for these two cases:
4570 -- Case of the source is unsigned and the target is signed
4572 if Is_Unsigned_Type (Source_Base_Type)
4573 and then not Is_Unsigned_Type (Target_Base_Type)
4575 -- If the source is unsigned and the target is signed, then we
4576 -- know that the source is not shorter than the target (otherwise
4577 -- the source base type would be in the target base type range).
4579 -- In other words, the unsigned type is either the same size as
4580 -- the target, or it is larger. It cannot be smaller.
4583 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
4585 -- We only need to check the low bound if the low bound of the
4586 -- target type is non-negative. If the low bound of the target
4587 -- type is negative, then we know that we will fit fine.
4589 -- If the high bound of the target type is negative, then we
4590 -- know we have a constraint error, since we can't possibly
4591 -- have a negative source.
4593 -- With these two checks out of the way, we can do the check
4594 -- using the source type safely
4596 -- This is definitely the most annoying case!
4598 -- [constraint_error
4599 -- when (Target_Type'First >= 0
4601 -- N < Source_Base_Type (Target_Type'First))
4602 -- or else Target_Type'Last < 0
4603 -- or else N > Source_Base_Type (Target_Type'Last)];
4605 -- We turn off all checks since we know that the conversions
4606 -- will work fine, given the guards for negative values.
4609 Make_Raise_Constraint_Error (Loc,
4615 Left_Opnd => Make_Op_Ge (Loc,
4617 Make_Attribute_Reference (Loc,
4619 New_Occurrence_Of (Target_Type, Loc),
4620 Attribute_Name => Name_First),
4621 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4625 Left_Opnd => Duplicate_Subexpr (N),
4627 Convert_To (Source_Base_Type,
4628 Make_Attribute_Reference (Loc,
4630 New_Occurrence_Of (Target_Type, Loc),
4631 Attribute_Name => Name_First)))),
4636 Make_Attribute_Reference (Loc,
4637 Prefix => New_Occurrence_Of (Target_Type, Loc),
4638 Attribute_Name => Name_Last),
4639 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
4643 Left_Opnd => Duplicate_Subexpr (N),
4645 Convert_To (Source_Base_Type,
4646 Make_Attribute_Reference (Loc,
4647 Prefix => New_Occurrence_Of (Target_Type, Loc),
4648 Attribute_Name => Name_Last)))),
4651 Suppress => All_Checks);
4653 -- Only remaining possibility is that the source is signed and
4654 -- the target is unsigned
4657 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
4658 and then Is_Unsigned_Type (Target_Base_Type));
4660 -- If the source is signed and the target is unsigned, then we
4661 -- know that the target is not shorter than the source (otherwise
4662 -- the target base type would be in the source base type range).
4664 -- In other words, the unsigned type is either the same size as
4665 -- the target, or it is larger. It cannot be smaller.
4667 -- Clearly we have an error if the source value is negative since
4668 -- no unsigned type can have negative values. If the source type
4669 -- is non-negative, then the check can be done using the target
4672 -- Tnn : constant Target_Base_Type (N) := Target_Type;
4674 -- [constraint_error
4675 -- when N < 0 or else Tnn not in Target_Type];
4677 -- We turn off all checks for the conversion of N to the target
4678 -- base type, since we generate the explicit check to ensure that
4679 -- the value is non-negative
4682 Tnn : constant Entity_Id :=
4683 Make_Defining_Identifier (Loc,
4684 Chars => New_Internal_Name ('T'));
4687 Insert_Actions (N, New_List (
4688 Make_Object_Declaration (Loc,
4689 Defining_Identifier => Tnn,
4690 Object_Definition =>
4691 New_Occurrence_Of (Target_Base_Type, Loc),
4692 Constant_Present => True,
4694 Make_Type_Conversion (Loc,
4696 New_Occurrence_Of (Target_Base_Type, Loc),
4697 Expression => Duplicate_Subexpr (N))),
4699 Make_Raise_Constraint_Error (Loc,
4704 Left_Opnd => Duplicate_Subexpr (N),
4705 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
4709 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
4711 New_Occurrence_Of (Target_Type, Loc))),
4714 Suppress => All_Checks);
4716 -- Set the Etype explicitly, because Insert_Actions may have
4717 -- placed the declaration in the freeze list for an enclosing
4718 -- construct, and thus it is not analyzed yet.
4720 Set_Etype (Tnn, Target_Base_Type);
4721 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
4725 end Generate_Range_Check;
4731 function Get_Check_Id (N : Name_Id) return Check_Id is
4733 -- For standard check name, we can do a direct computation
4735 if N in First_Check_Name .. Last_Check_Name then
4736 return Check_Id (N - (First_Check_Name - 1));
4738 -- For non-standard names added by pragma Check_Name, search table
4741 for J in All_Checks + 1 .. Check_Names.Last loop
4742 if Check_Names.Table (J) = N then
4748 -- No matching name found
4753 ---------------------
4754 -- Get_Discriminal --
4755 ---------------------
4757 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
4758 Loc : constant Source_Ptr := Sloc (E);
4763 -- The bound can be a bona fide parameter of a protected operation,
4764 -- rather than a prival encoded as an in-parameter.
4766 if No (Discriminal_Link (Entity (Bound))) then
4770 -- Climb the scope stack looking for an enclosing protected type. If
4771 -- we run out of scopes, return the bound itself.
4774 while Present (Sc) loop
4775 if Sc = Standard_Standard then
4778 elsif Ekind (Sc) = E_Protected_Type then
4785 D := First_Discriminant (Sc);
4786 while Present (D) loop
4787 if Chars (D) = Chars (Bound) then
4788 return New_Occurrence_Of (Discriminal (D), Loc);
4791 Next_Discriminant (D);
4795 end Get_Discriminal;
4797 ----------------------
4798 -- Get_Range_Checks --
4799 ----------------------
4801 function Get_Range_Checks
4803 Target_Typ : Entity_Id;
4804 Source_Typ : Entity_Id := Empty;
4805 Warn_Node : Node_Id := Empty) return Check_Result
4808 return Selected_Range_Checks
4809 (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
4810 end Get_Range_Checks;
4816 function Guard_Access
4819 Ck_Node : Node_Id) return Node_Id
4822 if Nkind (Cond) = N_Or_Else then
4823 Set_Paren_Count (Cond, 1);
4826 if Nkind (Ck_Node) = N_Allocator then
4833 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
4834 Right_Opnd => Make_Null (Loc)),
4835 Right_Opnd => Cond);
4839 -----------------------------
4840 -- Index_Checks_Suppressed --
4841 -----------------------------
4843 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
4845 if Present (E) and then Checks_May_Be_Suppressed (E) then
4846 return Is_Check_Suppressed (E, Index_Check);
4848 return Scope_Suppress (Index_Check);
4850 end Index_Checks_Suppressed;
4856 procedure Initialize is
4858 for J in Determine_Range_Cache_N'Range loop
4859 Determine_Range_Cache_N (J) := Empty;
4864 for J in Int range 1 .. All_Checks loop
4865 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
4869 -------------------------
4870 -- Insert_Range_Checks --
4871 -------------------------
4873 procedure Insert_Range_Checks
4874 (Checks : Check_Result;
4876 Suppress_Typ : Entity_Id;
4877 Static_Sloc : Source_Ptr := No_Location;
4878 Flag_Node : Node_Id := Empty;
4879 Do_Before : Boolean := False)
4881 Internal_Flag_Node : Node_Id := Flag_Node;
4882 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
4884 Check_Node : Node_Id;
4885 Checks_On : constant Boolean :=
4886 (not Index_Checks_Suppressed (Suppress_Typ))
4888 (not Range_Checks_Suppressed (Suppress_Typ));
4891 -- For now we just return if Checks_On is false, however this should be
4892 -- enhanced to check for an always True value in the condition and to
4893 -- generate a compilation warning???
4895 if not Expander_Active or else not Checks_On then
4899 if Static_Sloc = No_Location then
4900 Internal_Static_Sloc := Sloc (Node);
4903 if No (Flag_Node) then
4904 Internal_Flag_Node := Node;
4907 for J in 1 .. 2 loop
4908 exit when No (Checks (J));
4910 if Nkind (Checks (J)) = N_Raise_Constraint_Error
4911 and then Present (Condition (Checks (J)))
4913 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
4914 Check_Node := Checks (J);
4915 Mark_Rewrite_Insertion (Check_Node);
4918 Insert_Before_And_Analyze (Node, Check_Node);
4920 Insert_After_And_Analyze (Node, Check_Node);
4923 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
4928 Make_Raise_Constraint_Error (Internal_Static_Sloc,
4929 Reason => CE_Range_Check_Failed);
4930 Mark_Rewrite_Insertion (Check_Node);
4933 Insert_Before_And_Analyze (Node, Check_Node);
4935 Insert_After_And_Analyze (Node, Check_Node);
4939 end Insert_Range_Checks;
4941 ------------------------
4942 -- Insert_Valid_Check --
4943 ------------------------
4945 procedure Insert_Valid_Check (Expr : Node_Id) is
4946 Loc : constant Source_Ptr := Sloc (Expr);
4950 -- Do not insert if checks off, or if not checking validity
4952 if not Validity_Checks_On
4953 or else Range_Or_Validity_Checks_Suppressed (Expr)
4958 -- If we have a checked conversion, then validity check applies to
4959 -- the expression inside the conversion, not the result, since if
4960 -- the expression inside is valid, then so is the conversion result.
4963 while Nkind (Exp) = N_Type_Conversion loop
4964 Exp := Expression (Exp);
4967 -- We are about to insert the validity check for Exp. We save and
4968 -- reset the Do_Range_Check flag over this validity check, and then
4969 -- put it back for the final original reference (Exp may be rewritten).
4972 DRC : constant Boolean := Do_Range_Check (Exp);
4975 Set_Do_Range_Check (Exp, False);
4977 -- Insert the validity check. Note that we do this with validity
4978 -- checks turned off, to avoid recursion, we do not want validity
4979 -- checks on the validity checking code itself!
4983 Make_Raise_Constraint_Error (Loc,
4987 Make_Attribute_Reference (Loc,
4989 Duplicate_Subexpr_No_Checks (Exp, Name_Req => True),
4990 Attribute_Name => Name_Valid)),
4991 Reason => CE_Invalid_Data),
4992 Suppress => Validity_Check);
4994 -- If the expression is a a reference to an element of a bit-packed
4995 -- array, then it is rewritten as a renaming declaration. If the
4996 -- expression is an actual in a call, it has not been expanded,
4997 -- waiting for the proper point at which to do it. The same happens
4998 -- with renamings, so that we have to force the expansion now. This
4999 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
5002 if Is_Entity_Name (Exp)
5003 and then Nkind (Parent (Entity (Exp))) =
5004 N_Object_Renaming_Declaration
5007 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
5009 if Nkind (Old_Exp) = N_Indexed_Component
5010 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
5012 Expand_Packed_Element_Reference (Old_Exp);
5017 -- Put back the Do_Range_Check flag on the resulting (possibly
5018 -- rewritten) expression.
5020 -- Note: it might be thought that a validity check is not required
5021 -- when a range check is present, but that's not the case, because
5022 -- the back end is allowed to assume for the range check that the
5023 -- operand is within its declared range (an assumption that validity
5024 -- checking is all about NOT assuming!)
5026 -- Note: no need to worry about Possible_Local_Raise here, it will
5027 -- already have been called if original node has Do_Range_Check set.
5029 Set_Do_Range_Check (Exp, DRC);
5031 end Insert_Valid_Check;
5033 ----------------------------------
5034 -- Install_Null_Excluding_Check --
5035 ----------------------------------
5037 procedure Install_Null_Excluding_Check (N : Node_Id) is
5038 Loc : constant Source_Ptr := Sloc (N);
5039 Typ : constant Entity_Id := Etype (N);
5041 function In_Declarative_Region_Of_Subprogram_Body return Boolean;
5042 -- Determine whether node N, a reference to an *in* parameter, is
5043 -- inside the declarative region of the current subprogram body.
5045 procedure Mark_Non_Null;
5046 -- After installation of check, if the node in question is an entity
5047 -- name, then mark this entity as non-null if possible.
5049 ----------------------------------------------
5050 -- In_Declarative_Region_Of_Subprogram_Body --
5051 ----------------------------------------------
5053 function In_Declarative_Region_Of_Subprogram_Body return Boolean is
5054 E : constant Entity_Id := Entity (N);
5055 S : constant Entity_Id := Current_Scope;
5059 pragma Assert (Ekind (E) = E_In_Parameter);
5061 -- Two initial context checks. We must be inside a subprogram body
5062 -- with declarations and reference must not appear in nested scopes.
5064 if (Ekind (S) /= E_Function
5065 and then Ekind (S) /= E_Procedure)
5066 or else Scope (E) /= S
5071 S_Par := Parent (Parent (S));
5073 if Nkind (S_Par) /= N_Subprogram_Body
5074 or else No (Declarations (S_Par))
5084 -- Retrieve the declaration node of N (if any). Note that N
5085 -- may be a part of a complex initialization expression.
5089 while Present (P) loop
5091 -- While traversing the parent chain, we find that N
5092 -- belongs to a statement, thus it may never appear in
5093 -- a declarative region.
5095 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
5096 or else Nkind (P) = N_Procedure_Call_Statement
5101 if Nkind (P) in N_Declaration
5102 and then Nkind (P) not in N_Subprogram_Specification
5115 return List_Containing (N_Decl) = Declarations (S_Par);
5117 end In_Declarative_Region_Of_Subprogram_Body;
5123 procedure Mark_Non_Null is
5125 -- Only case of interest is if node N is an entity name
5127 if Is_Entity_Name (N) then
5129 -- For sure, we want to clear an indication that this is known to
5130 -- be null, since if we get past this check, it definitely is not!
5132 Set_Is_Known_Null (Entity (N), False);
5134 -- We can mark the entity as known to be non-null if either it is
5135 -- safe to capture the value, or in the case of an IN parameter,
5136 -- which is a constant, if the check we just installed is in the
5137 -- declarative region of the subprogram body. In this latter case,
5138 -- a check is decisive for the rest of the body, since we know we
5139 -- must complete all declarations before executing the body.
5141 if Safe_To_Capture_Value (N, Entity (N))
5143 (Ekind (Entity (N)) = E_In_Parameter
5144 and then In_Declarative_Region_Of_Subprogram_Body)
5146 Set_Is_Known_Non_Null (Entity (N));
5151 -- Start of processing for Install_Null_Excluding_Check
5154 pragma Assert (Is_Access_Type (Typ));
5156 -- No check inside a generic (why not???)
5158 if Inside_A_Generic then
5162 -- No check needed if known to be non-null
5164 if Known_Non_Null (N) then
5168 -- If known to be null, here is where we generate a compile time check
5170 if Known_Null (N) then
5171 Apply_Compile_Time_Constraint_Error
5173 "null value not allowed here?",
5174 CE_Access_Check_Failed);
5179 -- If entity is never assigned, for sure a warning is appropriate
5181 if Is_Entity_Name (N) then
5182 Check_Unset_Reference (N);
5185 -- No check needed if checks are suppressed on the range. Note that we
5186 -- don't set Is_Known_Non_Null in this case (we could legitimately do
5187 -- so, since the program is erroneous, but we don't like to casually
5188 -- propagate such conclusions from erroneosity).
5190 if Access_Checks_Suppressed (Typ) then
5194 -- No check needed for access to concurrent record types generated by
5195 -- the expander. This is not just an optimization (though it does indeed
5196 -- remove junk checks). It also avoids generation of junk warnings.
5198 if Nkind (N) in N_Has_Chars
5199 and then Chars (N) = Name_uObject
5200 and then Is_Concurrent_Record_Type
5201 (Directly_Designated_Type (Etype (N)))
5206 -- Otherwise install access check
5209 Make_Raise_Constraint_Error (Loc,
5212 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
5213 Right_Opnd => Make_Null (Loc)),
5214 Reason => CE_Access_Check_Failed));
5217 end Install_Null_Excluding_Check;
5219 --------------------------
5220 -- Install_Static_Check --
5221 --------------------------
5223 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
5224 Stat : constant Boolean := Is_Static_Expression (R_Cno);
5225 Typ : constant Entity_Id := Etype (R_Cno);
5229 Make_Raise_Constraint_Error (Loc,
5230 Reason => CE_Range_Check_Failed));
5231 Set_Analyzed (R_Cno);
5232 Set_Etype (R_Cno, Typ);
5233 Set_Raises_Constraint_Error (R_Cno);
5234 Set_Is_Static_Expression (R_Cno, Stat);
5235 end Install_Static_Check;
5237 ---------------------
5238 -- Kill_All_Checks --
5239 ---------------------
5241 procedure Kill_All_Checks is
5243 if Debug_Flag_CC then
5244 w ("Kill_All_Checks");
5247 -- We reset the number of saved checks to zero, and also modify all
5248 -- stack entries for statement ranges to indicate that the number of
5249 -- checks at each level is now zero.
5251 Num_Saved_Checks := 0;
5253 -- Note: the Int'Min here avoids any possibility of J being out of
5254 -- range when called from e.g. Conditional_Statements_Begin.
5256 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
5257 Saved_Checks_Stack (J) := 0;
5259 end Kill_All_Checks;
5265 procedure Kill_Checks (V : Entity_Id) is
5267 if Debug_Flag_CC then
5268 w ("Kill_Checks for entity", Int (V));
5271 for J in 1 .. Num_Saved_Checks loop
5272 if Saved_Checks (J).Entity = V then
5273 if Debug_Flag_CC then
5274 w (" Checks killed for saved check ", J);
5277 Saved_Checks (J).Killed := True;
5282 ------------------------------
5283 -- Length_Checks_Suppressed --
5284 ------------------------------
5286 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
5288 if Present (E) and then Checks_May_Be_Suppressed (E) then
5289 return Is_Check_Suppressed (E, Length_Check);
5291 return Scope_Suppress (Length_Check);
5293 end Length_Checks_Suppressed;
5295 --------------------------------
5296 -- Overflow_Checks_Suppressed --
5297 --------------------------------
5299 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
5301 if Present (E) and then Checks_May_Be_Suppressed (E) then
5302 return Is_Check_Suppressed (E, Overflow_Check);
5304 return Scope_Suppress (Overflow_Check);
5306 end Overflow_Checks_Suppressed;
5307 -----------------------------
5308 -- Range_Checks_Suppressed --
5309 -----------------------------
5311 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
5315 -- Note: for now we always suppress range checks on Vax float types,
5316 -- since Gigi does not know how to generate these checks.
5318 if Vax_Float (E) then
5320 elsif Kill_Range_Checks (E) then
5322 elsif Checks_May_Be_Suppressed (E) then
5323 return Is_Check_Suppressed (E, Range_Check);
5327 return Scope_Suppress (Range_Check);
5328 end Range_Checks_Suppressed;
5330 -----------------------------------------
5331 -- Range_Or_Validity_Checks_Suppressed --
5332 -----------------------------------------
5334 -- Note: the coding would be simpler here if we simply made appropriate
5335 -- calls to Range/Validity_Checks_Suppressed, but that would result in
5336 -- duplicated checks which we prefer to avoid.
5338 function Range_Or_Validity_Checks_Suppressed
5339 (Expr : Node_Id) return Boolean
5342 -- Immediate return if scope checks suppressed for either check
5344 if Scope_Suppress (Range_Check) or Scope_Suppress (Validity_Check) then
5348 -- If no expression, that's odd, decide that checks are suppressed,
5349 -- since we don't want anyone trying to do checks in this case, which
5350 -- is most likely the result of some other error.
5356 -- Expression is present, so perform suppress checks on type
5359 Typ : constant Entity_Id := Etype (Expr);
5361 if Vax_Float (Typ) then
5363 elsif Checks_May_Be_Suppressed (Typ)
5364 and then (Is_Check_Suppressed (Typ, Range_Check)
5366 Is_Check_Suppressed (Typ, Validity_Check))
5372 -- If expression is an entity name, perform checks on this entity
5374 if Is_Entity_Name (Expr) then
5376 Ent : constant Entity_Id := Entity (Expr);
5378 if Checks_May_Be_Suppressed (Ent) then
5379 return Is_Check_Suppressed (Ent, Range_Check)
5380 or else Is_Check_Suppressed (Ent, Validity_Check);
5385 -- If we fall through, no checks suppressed
5388 end Range_Or_Validity_Checks_Suppressed;
5394 procedure Remove_Checks (Expr : Node_Id) is
5395 function Process (N : Node_Id) return Traverse_Result;
5396 -- Process a single node during the traversal
5398 procedure Traverse is new Traverse_Proc (Process);
5399 -- The traversal procedure itself
5405 function Process (N : Node_Id) return Traverse_Result is
5407 if Nkind (N) not in N_Subexpr then
5411 Set_Do_Range_Check (N, False);
5415 Traverse (Left_Opnd (N));
5418 when N_Attribute_Reference =>
5419 Set_Do_Overflow_Check (N, False);
5421 when N_Function_Call =>
5422 Set_Do_Tag_Check (N, False);
5425 Set_Do_Overflow_Check (N, False);
5429 Set_Do_Division_Check (N, False);
5432 Set_Do_Length_Check (N, False);
5435 Set_Do_Division_Check (N, False);
5438 Set_Do_Length_Check (N, False);
5441 Set_Do_Division_Check (N, False);
5444 Set_Do_Length_Check (N, False);
5451 Traverse (Left_Opnd (N));
5454 when N_Selected_Component =>
5455 Set_Do_Discriminant_Check (N, False);
5457 when N_Type_Conversion =>
5458 Set_Do_Length_Check (N, False);
5459 Set_Do_Tag_Check (N, False);
5460 Set_Do_Overflow_Check (N, False);
5469 -- Start of processing for Remove_Checks
5475 ----------------------------
5476 -- Selected_Length_Checks --
5477 ----------------------------
5479 function Selected_Length_Checks
5481 Target_Typ : Entity_Id;
5482 Source_Typ : Entity_Id;
5483 Warn_Node : Node_Id) return Check_Result
5485 Loc : constant Source_Ptr := Sloc (Ck_Node);
5488 Expr_Actual : Node_Id;
5490 Cond : Node_Id := Empty;
5491 Do_Access : Boolean := False;
5492 Wnode : Node_Id := Warn_Node;
5493 Ret_Result : Check_Result := (Empty, Empty);
5494 Num_Checks : Natural := 0;
5496 procedure Add_Check (N : Node_Id);
5497 -- Adds the action given to Ret_Result if N is non-Empty
5499 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
5500 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
5501 -- Comments required ???
5503 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
5504 -- True for equal literals and for nodes that denote the same constant
5505 -- entity, even if its value is not a static constant. This includes the
5506 -- case of a discriminal reference within an init proc. Removes some
5507 -- obviously superfluous checks.
5509 function Length_E_Cond
5510 (Exptyp : Entity_Id;
5512 Indx : Nat) return Node_Id;
5513 -- Returns expression to compute:
5514 -- Typ'Length /= Exptyp'Length
5516 function Length_N_Cond
5519 Indx : Nat) return Node_Id;
5520 -- Returns expression to compute:
5521 -- Typ'Length /= Expr'Length
5527 procedure Add_Check (N : Node_Id) is
5531 -- For now, ignore attempt to place more than 2 checks ???
5533 if Num_Checks = 2 then
5537 pragma Assert (Num_Checks <= 1);
5538 Num_Checks := Num_Checks + 1;
5539 Ret_Result (Num_Checks) := N;
5547 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
5548 SE : constant Entity_Id := Scope (E);
5550 E1 : Entity_Id := E;
5553 if Ekind (Scope (E)) = E_Record_Type
5554 and then Has_Discriminants (Scope (E))
5556 N := Build_Discriminal_Subtype_Of_Component (E);
5559 Insert_Action (Ck_Node, N);
5560 E1 := Defining_Identifier (N);
5564 if Ekind (E1) = E_String_Literal_Subtype then
5566 Make_Integer_Literal (Loc,
5567 Intval => String_Literal_Length (E1));
5569 elsif SE /= Standard_Standard
5570 and then Ekind (Scope (SE)) = E_Protected_Type
5571 and then Has_Discriminants (Scope (SE))
5572 and then Has_Completion (Scope (SE))
5573 and then not Inside_Init_Proc
5575 -- If the type whose length is needed is a private component
5576 -- constrained by a discriminant, we must expand the 'Length
5577 -- attribute into an explicit computation, using the discriminal
5578 -- of the current protected operation. This is because the actual
5579 -- type of the prival is constructed after the protected opera-
5580 -- tion has been fully expanded.
5583 Indx_Type : Node_Id;
5586 Do_Expand : Boolean := False;
5589 Indx_Type := First_Index (E);
5591 for J in 1 .. Indx - 1 loop
5592 Next_Index (Indx_Type);
5595 Get_Index_Bounds (Indx_Type, Lo, Hi);
5597 if Nkind (Lo) = N_Identifier
5598 and then Ekind (Entity (Lo)) = E_In_Parameter
5600 Lo := Get_Discriminal (E, Lo);
5604 if Nkind (Hi) = N_Identifier
5605 and then Ekind (Entity (Hi)) = E_In_Parameter
5607 Hi := Get_Discriminal (E, Hi);
5612 if not Is_Entity_Name (Lo) then
5613 Lo := Duplicate_Subexpr_No_Checks (Lo);
5616 if not Is_Entity_Name (Hi) then
5617 Lo := Duplicate_Subexpr_No_Checks (Hi);
5623 Make_Op_Subtract (Loc,
5627 Right_Opnd => Make_Integer_Literal (Loc, 1));
5632 Make_Attribute_Reference (Loc,
5633 Attribute_Name => Name_Length,
5635 New_Occurrence_Of (E1, Loc));
5638 Set_Expressions (N, New_List (
5639 Make_Integer_Literal (Loc, Indx)));
5648 Make_Attribute_Reference (Loc,
5649 Attribute_Name => Name_Length,
5651 New_Occurrence_Of (E1, Loc));
5654 Set_Expressions (N, New_List (
5655 Make_Integer_Literal (Loc, Indx)));
5666 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
5669 Make_Attribute_Reference (Loc,
5670 Attribute_Name => Name_Length,
5672 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
5673 Expressions => New_List (
5674 Make_Integer_Literal (Loc, Indx)));
5681 function Length_E_Cond
5682 (Exptyp : Entity_Id;
5684 Indx : Nat) return Node_Id
5689 Left_Opnd => Get_E_Length (Typ, Indx),
5690 Right_Opnd => Get_E_Length (Exptyp, Indx));
5697 function Length_N_Cond
5700 Indx : Nat) return Node_Id
5705 Left_Opnd => Get_E_Length (Typ, Indx),
5706 Right_Opnd => Get_N_Length (Expr, Indx));
5713 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
5716 (Nkind (L) = N_Integer_Literal
5717 and then Nkind (R) = N_Integer_Literal
5718 and then Intval (L) = Intval (R))
5722 and then Ekind (Entity (L)) = E_Constant
5723 and then ((Is_Entity_Name (R)
5724 and then Entity (L) = Entity (R))
5726 (Nkind (R) = N_Type_Conversion
5727 and then Is_Entity_Name (Expression (R))
5728 and then Entity (L) = Entity (Expression (R)))))
5732 and then Ekind (Entity (R)) = E_Constant
5733 and then Nkind (L) = N_Type_Conversion
5734 and then Is_Entity_Name (Expression (L))
5735 and then Entity (R) = Entity (Expression (L)))
5739 and then Is_Entity_Name (R)
5740 and then Entity (L) = Entity (R)
5741 and then Ekind (Entity (L)) = E_In_Parameter
5742 and then Inside_Init_Proc);
5745 -- Start of processing for Selected_Length_Checks
5748 if not Expander_Active then
5752 if Target_Typ = Any_Type
5753 or else Target_Typ = Any_Composite
5754 or else Raises_Constraint_Error (Ck_Node)
5763 T_Typ := Target_Typ;
5765 if No (Source_Typ) then
5766 S_Typ := Etype (Ck_Node);
5768 S_Typ := Source_Typ;
5771 if S_Typ = Any_Type or else S_Typ = Any_Composite then
5775 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
5776 S_Typ := Designated_Type (S_Typ);
5777 T_Typ := Designated_Type (T_Typ);
5780 -- A simple optimization for the null case
5782 if Known_Null (Ck_Node) then
5787 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
5788 if Is_Constrained (T_Typ) then
5790 -- The checking code to be generated will freeze the
5791 -- corresponding array type. However, we must freeze the
5792 -- type now, so that the freeze node does not appear within
5793 -- the generated condional expression, but ahead of it.
5795 Freeze_Before (Ck_Node, T_Typ);
5797 Expr_Actual := Get_Referenced_Object (Ck_Node);
5798 Exptyp := Get_Actual_Subtype (Ck_Node);
5800 if Is_Access_Type (Exptyp) then
5801 Exptyp := Designated_Type (Exptyp);
5804 -- String_Literal case. This needs to be handled specially be-
5805 -- cause no index types are available for string literals. The
5806 -- condition is simply:
5808 -- T_Typ'Length = string-literal-length
5810 if Nkind (Expr_Actual) = N_String_Literal
5811 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
5815 Left_Opnd => Get_E_Length (T_Typ, 1),
5817 Make_Integer_Literal (Loc,
5819 String_Literal_Length (Etype (Expr_Actual))));
5821 -- General array case. Here we have a usable actual subtype for
5822 -- the expression, and the condition is built from the two types
5825 -- T_Typ'Length /= Exptyp'Length or else
5826 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
5827 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
5830 elsif Is_Constrained (Exptyp) then
5832 Ndims : constant Nat := Number_Dimensions (T_Typ);
5845 -- At the library level, we need to ensure that the type of
5846 -- the object is elaborated before the check itself is
5847 -- emitted. This is only done if the object is in the
5848 -- current compilation unit, otherwise the type is frozen
5849 -- and elaborated in its unit.
5851 if Is_Itype (Exptyp)
5853 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
5855 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
5856 and then In_Open_Scopes (Scope (Exptyp))
5858 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
5859 Set_Itype (Ref_Node, Exptyp);
5860 Insert_Action (Ck_Node, Ref_Node);
5863 L_Index := First_Index (T_Typ);
5864 R_Index := First_Index (Exptyp);
5866 for Indx in 1 .. Ndims loop
5867 if not (Nkind (L_Index) = N_Raise_Constraint_Error
5869 Nkind (R_Index) = N_Raise_Constraint_Error)
5871 Get_Index_Bounds (L_Index, L_Low, L_High);
5872 Get_Index_Bounds (R_Index, R_Low, R_High);
5874 -- Deal with compile time length check. Note that we
5875 -- skip this in the access case, because the access
5876 -- value may be null, so we cannot know statically.
5879 and then Compile_Time_Known_Value (L_Low)
5880 and then Compile_Time_Known_Value (L_High)
5881 and then Compile_Time_Known_Value (R_Low)
5882 and then Compile_Time_Known_Value (R_High)
5884 if Expr_Value (L_High) >= Expr_Value (L_Low) then
5885 L_Length := Expr_Value (L_High) -
5886 Expr_Value (L_Low) + 1;
5888 L_Length := UI_From_Int (0);
5891 if Expr_Value (R_High) >= Expr_Value (R_Low) then
5892 R_Length := Expr_Value (R_High) -
5893 Expr_Value (R_Low) + 1;
5895 R_Length := UI_From_Int (0);
5898 if L_Length > R_Length then
5900 (Compile_Time_Constraint_Error
5901 (Wnode, "too few elements for}?", T_Typ));
5903 elsif L_Length < R_Length then
5905 (Compile_Time_Constraint_Error
5906 (Wnode, "too many elements for}?", T_Typ));
5909 -- The comparison for an individual index subtype
5910 -- is omitted if the corresponding index subtypes
5911 -- statically match, since the result is known to
5912 -- be true. Note that this test is worth while even
5913 -- though we do static evaluation, because non-static
5914 -- subtypes can statically match.
5917 Subtypes_Statically_Match
5918 (Etype (L_Index), Etype (R_Index))
5921 (Same_Bounds (L_Low, R_Low)
5922 and then Same_Bounds (L_High, R_High))
5925 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
5934 -- Handle cases where we do not get a usable actual subtype that
5935 -- is constrained. This happens for example in the function call
5936 -- and explicit dereference cases. In these cases, we have to get
5937 -- the length or range from the expression itself, making sure we
5938 -- do not evaluate it more than once.
5940 -- Here Ck_Node is the original expression, or more properly the
5941 -- result of applying Duplicate_Expr to the original tree, forcing
5942 -- the result to be a name.
5946 Ndims : constant Nat := Number_Dimensions (T_Typ);
5949 -- Build the condition for the explicit dereference case
5951 for Indx in 1 .. Ndims loop
5953 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
5960 -- Construct the test and insert into the tree
5962 if Present (Cond) then
5964 Cond := Guard_Access (Cond, Loc, Ck_Node);
5968 (Make_Raise_Constraint_Error (Loc,
5970 Reason => CE_Length_Check_Failed));
5974 end Selected_Length_Checks;
5976 ---------------------------
5977 -- Selected_Range_Checks --
5978 ---------------------------
5980 function Selected_Range_Checks
5982 Target_Typ : Entity_Id;
5983 Source_Typ : Entity_Id;
5984 Warn_Node : Node_Id) return Check_Result
5986 Loc : constant Source_Ptr := Sloc (Ck_Node);
5989 Expr_Actual : Node_Id;
5991 Cond : Node_Id := Empty;
5992 Do_Access : Boolean := False;
5993 Wnode : Node_Id := Warn_Node;
5994 Ret_Result : Check_Result := (Empty, Empty);
5995 Num_Checks : Integer := 0;
5997 procedure Add_Check (N : Node_Id);
5998 -- Adds the action given to Ret_Result if N is non-Empty
6000 function Discrete_Range_Cond
6002 Typ : Entity_Id) return Node_Id;
6003 -- Returns expression to compute:
6004 -- Low_Bound (Expr) < Typ'First
6006 -- High_Bound (Expr) > Typ'Last
6008 function Discrete_Expr_Cond
6010 Typ : Entity_Id) return Node_Id;
6011 -- Returns expression to compute:
6016 function Get_E_First_Or_Last
6019 Nam : Name_Id) return Node_Id;
6020 -- Returns expression to compute:
6021 -- E'First or E'Last
6023 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
6024 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
6025 -- Returns expression to compute:
6026 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
6028 function Range_E_Cond
6029 (Exptyp : Entity_Id;
6033 -- Returns expression to compute:
6034 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
6036 function Range_Equal_E_Cond
6037 (Exptyp : Entity_Id;
6039 Indx : Nat) return Node_Id;
6040 -- Returns expression to compute:
6041 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
6043 function Range_N_Cond
6046 Indx : Nat) return Node_Id;
6047 -- Return expression to compute:
6048 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
6054 procedure Add_Check (N : Node_Id) is
6058 -- For now, ignore attempt to place more than 2 checks ???
6060 if Num_Checks = 2 then
6064 pragma Assert (Num_Checks <= 1);
6065 Num_Checks := Num_Checks + 1;
6066 Ret_Result (Num_Checks) := N;
6070 -------------------------
6071 -- Discrete_Expr_Cond --
6072 -------------------------
6074 function Discrete_Expr_Cond
6076 Typ : Entity_Id) return Node_Id
6084 Convert_To (Base_Type (Typ),
6085 Duplicate_Subexpr_No_Checks (Expr)),
6087 Convert_To (Base_Type (Typ),
6088 Get_E_First_Or_Last (Typ, 0, Name_First))),
6093 Convert_To (Base_Type (Typ),
6094 Duplicate_Subexpr_No_Checks (Expr)),
6098 Get_E_First_Or_Last (Typ, 0, Name_Last))));
6099 end Discrete_Expr_Cond;
6101 -------------------------
6102 -- Discrete_Range_Cond --
6103 -------------------------
6105 function Discrete_Range_Cond
6107 Typ : Entity_Id) return Node_Id
6109 LB : Node_Id := Low_Bound (Expr);
6110 HB : Node_Id := High_Bound (Expr);
6112 Left_Opnd : Node_Id;
6113 Right_Opnd : Node_Id;
6116 if Nkind (LB) = N_Identifier
6117 and then Ekind (Entity (LB)) = E_Discriminant
6119 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6122 if Nkind (HB) = N_Identifier
6123 and then Ekind (Entity (HB)) = E_Discriminant
6125 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6132 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
6136 (Base_Type (Typ), Get_E_First_Or_Last (Typ, 0, Name_First)));
6138 if Base_Type (Typ) = Typ then
6141 elsif Compile_Time_Known_Value (High_Bound (Scalar_Range (Typ)))
6143 Compile_Time_Known_Value (High_Bound (Scalar_Range
6146 if Is_Floating_Point_Type (Typ) then
6147 if Expr_Value_R (High_Bound (Scalar_Range (Typ))) =
6148 Expr_Value_R (High_Bound (Scalar_Range (Base_Type (Typ))))
6154 if Expr_Value (High_Bound (Scalar_Range (Typ))) =
6155 Expr_Value (High_Bound (Scalar_Range (Base_Type (Typ))))
6166 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
6171 Get_E_First_Or_Last (Typ, 0, Name_Last)));
6173 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
6174 end Discrete_Range_Cond;
6176 -------------------------
6177 -- Get_E_First_Or_Last --
6178 -------------------------
6180 function Get_E_First_Or_Last
6183 Nam : Name_Id) return Node_Id
6191 if Is_Array_Type (E) then
6192 N := First_Index (E);
6194 for J in 2 .. Indx loop
6199 N := Scalar_Range (E);
6202 if Nkind (N) = N_Subtype_Indication then
6203 LB := Low_Bound (Range_Expression (Constraint (N)));
6204 HB := High_Bound (Range_Expression (Constraint (N)));
6206 elsif Is_Entity_Name (N) then
6207 LB := Type_Low_Bound (Etype (N));
6208 HB := Type_High_Bound (Etype (N));
6211 LB := Low_Bound (N);
6212 HB := High_Bound (N);
6215 if Nam = Name_First then
6221 if Nkind (Bound) = N_Identifier
6222 and then Ekind (Entity (Bound)) = E_Discriminant
6224 -- If this is a task discriminant, and we are the body, we must
6225 -- retrieve the corresponding body discriminal. This is another
6226 -- consequence of the early creation of discriminals, and the
6227 -- need to generate constraint checks before their declarations
6228 -- are made visible.
6230 if Is_Concurrent_Record_Type (Scope (Entity (Bound))) then
6232 Tsk : constant Entity_Id :=
6233 Corresponding_Concurrent_Type
6234 (Scope (Entity (Bound)));
6238 if In_Open_Scopes (Tsk)
6239 and then Has_Completion (Tsk)
6241 -- Find discriminant of original task, and use its
6242 -- current discriminal, which is the renaming within
6245 Disc := First_Discriminant (Tsk);
6246 while Present (Disc) loop
6247 if Chars (Disc) = Chars (Entity (Bound)) then
6248 Set_Scope (Discriminal (Disc), Tsk);
6249 return New_Occurrence_Of (Discriminal (Disc), Loc);
6252 Next_Discriminant (Disc);
6255 -- That loop should always succeed in finding a matching
6256 -- entry and returning. Fatal error if not.
6258 raise Program_Error;
6262 New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6266 return New_Occurrence_Of (Discriminal (Entity (Bound)), Loc);
6269 elsif Nkind (Bound) = N_Identifier
6270 and then Ekind (Entity (Bound)) = E_In_Parameter
6271 and then not Inside_Init_Proc
6273 return Get_Discriminal (E, Bound);
6275 elsif Nkind (Bound) = N_Integer_Literal then
6276 return Make_Integer_Literal (Loc, Intval (Bound));
6278 -- Case of a bound rewritten to an N_Raise_Constraint_Error node
6279 -- because it is an out-of-range value. Duplicate_Subexpr cannot be
6280 -- called on this node because an N_Raise_Constraint_Error is not
6281 -- side effect free, and we may not assume that we are in the proper
6282 -- context to remove side effects on it at the point of reference.
6284 elsif Nkind (Bound) = N_Raise_Constraint_Error then
6285 return New_Copy_Tree (Bound);
6288 return Duplicate_Subexpr_No_Checks (Bound);
6290 end Get_E_First_Or_Last;
6296 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
6299 Make_Attribute_Reference (Loc,
6300 Attribute_Name => Name_First,
6302 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6303 Expressions => New_List (
6304 Make_Integer_Literal (Loc, Indx)));
6311 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
6314 Make_Attribute_Reference (Loc,
6315 Attribute_Name => Name_Last,
6317 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
6318 Expressions => New_List (
6319 Make_Integer_Literal (Loc, Indx)));
6326 function Range_E_Cond
6327 (Exptyp : Entity_Id;
6329 Indx : Nat) return Node_Id
6336 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6337 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6341 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6342 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6345 ------------------------
6346 -- Range_Equal_E_Cond --
6347 ------------------------
6349 function Range_Equal_E_Cond
6350 (Exptyp : Entity_Id;
6352 Indx : Nat) return Node_Id
6359 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_First),
6360 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6363 Left_Opnd => Get_E_First_Or_Last (Exptyp, Indx, Name_Last),
6364 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6365 end Range_Equal_E_Cond;
6371 function Range_N_Cond
6374 Indx : Nat) return Node_Id
6381 Left_Opnd => Get_N_First (Expr, Indx),
6382 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_First)),
6386 Left_Opnd => Get_N_Last (Expr, Indx),
6387 Right_Opnd => Get_E_First_Or_Last (Typ, Indx, Name_Last)));
6390 -- Start of processing for Selected_Range_Checks
6393 if not Expander_Active then
6397 if Target_Typ = Any_Type
6398 or else Target_Typ = Any_Composite
6399 or else Raises_Constraint_Error (Ck_Node)
6408 T_Typ := Target_Typ;
6410 if No (Source_Typ) then
6411 S_Typ := Etype (Ck_Node);
6413 S_Typ := Source_Typ;
6416 if S_Typ = Any_Type or else S_Typ = Any_Composite then
6420 -- The order of evaluating T_Typ before S_Typ seems to be critical
6421 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
6422 -- in, and since Node can be an N_Range node, it might be invalid.
6423 -- Should there be an assert check somewhere for taking the Etype of
6424 -- an N_Range node ???
6426 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
6427 S_Typ := Designated_Type (S_Typ);
6428 T_Typ := Designated_Type (T_Typ);
6431 -- A simple optimization for the null case
6433 if Known_Null (Ck_Node) then
6438 -- For an N_Range Node, check for a null range and then if not
6439 -- null generate a range check action.
6441 if Nkind (Ck_Node) = N_Range then
6443 -- There's no point in checking a range against itself
6445 if Ck_Node = Scalar_Range (T_Typ) then
6450 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
6451 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
6452 LB : constant Node_Id := Low_Bound (Ck_Node);
6453 HB : constant Node_Id := High_Bound (Ck_Node);
6454 Null_Range : Boolean;
6456 Out_Of_Range_L : Boolean;
6457 Out_Of_Range_H : Boolean;
6460 -- Check for case where everything is static and we can
6461 -- do the check at compile time. This is skipped if we
6462 -- have an access type, since the access value may be null.
6464 -- ??? This code can be improved since you only need to know
6465 -- that the two respective bounds (LB & T_LB or HB & T_HB)
6466 -- are known at compile time to emit pertinent messages.
6468 if Compile_Time_Known_Value (LB)
6469 and then Compile_Time_Known_Value (HB)
6470 and then Compile_Time_Known_Value (T_LB)
6471 and then Compile_Time_Known_Value (T_HB)
6472 and then not Do_Access
6474 -- Floating-point case
6476 if Is_Floating_Point_Type (S_Typ) then
6477 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
6479 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
6481 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
6484 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
6486 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
6488 -- Fixed or discrete type case
6491 Null_Range := Expr_Value (HB) < Expr_Value (LB);
6493 (Expr_Value (LB) < Expr_Value (T_LB))
6495 (Expr_Value (LB) > Expr_Value (T_HB));
6498 (Expr_Value (HB) > Expr_Value (T_HB))
6500 (Expr_Value (HB) < Expr_Value (T_LB));
6503 if not Null_Range then
6504 if Out_Of_Range_L then
6505 if No (Warn_Node) then
6507 (Compile_Time_Constraint_Error
6508 (Low_Bound (Ck_Node),
6509 "static value out of range of}?", T_Typ));
6513 (Compile_Time_Constraint_Error
6515 "static range out of bounds of}?", T_Typ));
6519 if Out_Of_Range_H then
6520 if No (Warn_Node) then
6522 (Compile_Time_Constraint_Error
6523 (High_Bound (Ck_Node),
6524 "static value out of range of}?", T_Typ));
6528 (Compile_Time_Constraint_Error
6530 "static range out of bounds of}?", T_Typ));
6538 LB : Node_Id := Low_Bound (Ck_Node);
6539 HB : Node_Id := High_Bound (Ck_Node);
6542 -- If either bound is a discriminant and we are within the
6543 -- record declaration, it is a use of the discriminant in a
6544 -- constraint of a component, and nothing can be checked
6545 -- here. The check will be emitted within the init proc.
6546 -- Before then, the discriminal has no real meaning.
6547 -- Similarly, if the entity is a discriminal, there is no
6548 -- check to perform yet.
6550 -- The same holds within a discriminated synchronized type,
6551 -- where the discriminant may constrain a component or an
6554 if Nkind (LB) = N_Identifier
6555 and then Denotes_Discriminant (LB, True)
6557 if Current_Scope = Scope (Entity (LB))
6558 or else Is_Concurrent_Type (Current_Scope)
6559 or else Ekind (Entity (LB)) /= E_Discriminant
6564 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
6568 if Nkind (HB) = N_Identifier
6569 and then Denotes_Discriminant (HB, True)
6571 if Current_Scope = Scope (Entity (HB))
6572 or else Is_Concurrent_Type (Current_Scope)
6573 or else Ekind (Entity (HB)) /= E_Discriminant
6578 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
6582 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
6583 Set_Paren_Count (Cond, 1);
6589 Left_Opnd => Duplicate_Subexpr_No_Checks (HB),
6590 Right_Opnd => Duplicate_Subexpr_No_Checks (LB)),
6591 Right_Opnd => Cond);
6596 elsif Is_Scalar_Type (S_Typ) then
6598 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
6599 -- except the above simply sets a flag in the node and lets
6600 -- gigi generate the check base on the Etype of the expression.
6601 -- Sometimes, however we want to do a dynamic check against an
6602 -- arbitrary target type, so we do that here.
6604 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
6605 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6607 -- For literals, we can tell if the constraint error will be
6608 -- raised at compile time, so we never need a dynamic check, but
6609 -- if the exception will be raised, then post the usual warning,
6610 -- and replace the literal with a raise constraint error
6611 -- expression. As usual, skip this for access types
6613 elsif Compile_Time_Known_Value (Ck_Node)
6614 and then not Do_Access
6617 LB : constant Node_Id := Type_Low_Bound (T_Typ);
6618 UB : constant Node_Id := Type_High_Bound (T_Typ);
6620 Out_Of_Range : Boolean;
6621 Static_Bounds : constant Boolean :=
6622 Compile_Time_Known_Value (LB)
6623 and Compile_Time_Known_Value (UB);
6626 -- Following range tests should use Sem_Eval routine ???
6628 if Static_Bounds then
6629 if Is_Floating_Point_Type (S_Typ) then
6631 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
6633 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
6635 else -- fixed or discrete type
6637 Expr_Value (Ck_Node) < Expr_Value (LB)
6639 Expr_Value (Ck_Node) > Expr_Value (UB);
6642 -- Bounds of the type are static and the literal is
6643 -- out of range so make a warning message.
6645 if Out_Of_Range then
6646 if No (Warn_Node) then
6648 (Compile_Time_Constraint_Error
6650 "static value out of range of}?", T_Typ));
6654 (Compile_Time_Constraint_Error
6656 "static value out of range of}?", T_Typ));
6661 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6665 -- Here for the case of a non-static expression, we need a runtime
6666 -- check unless the source type range is guaranteed to be in the
6667 -- range of the target type.
6670 if not In_Subrange_Of (S_Typ, T_Typ) then
6671 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
6676 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
6677 if Is_Constrained (T_Typ) then
6679 Expr_Actual := Get_Referenced_Object (Ck_Node);
6680 Exptyp := Get_Actual_Subtype (Expr_Actual);
6682 if Is_Access_Type (Exptyp) then
6683 Exptyp := Designated_Type (Exptyp);
6686 -- String_Literal case. This needs to be handled specially be-
6687 -- cause no index types are available for string literals. The
6688 -- condition is simply:
6690 -- T_Typ'Length = string-literal-length
6692 if Nkind (Expr_Actual) = N_String_Literal then
6695 -- General array case. Here we have a usable actual subtype for
6696 -- the expression, and the condition is built from the two types
6698 -- T_Typ'First < Exptyp'First or else
6699 -- T_Typ'Last > Exptyp'Last or else
6700 -- T_Typ'First(1) < Exptyp'First(1) or else
6701 -- T_Typ'Last(1) > Exptyp'Last(1) or else
6704 elsif Is_Constrained (Exptyp) then
6706 Ndims : constant Nat := Number_Dimensions (T_Typ);
6712 L_Index := First_Index (T_Typ);
6713 R_Index := First_Index (Exptyp);
6715 for Indx in 1 .. Ndims loop
6716 if not (Nkind (L_Index) = N_Raise_Constraint_Error
6718 Nkind (R_Index) = N_Raise_Constraint_Error)
6720 -- Deal with compile time length check. Note that we
6721 -- skip this in the access case, because the access
6722 -- value may be null, so we cannot know statically.
6725 Subtypes_Statically_Match
6726 (Etype (L_Index), Etype (R_Index))
6728 -- If the target type is constrained then we
6729 -- have to check for exact equality of bounds
6730 -- (required for qualified expressions).
6732 if Is_Constrained (T_Typ) then
6735 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
6738 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
6749 -- Handle cases where we do not get a usable actual subtype that
6750 -- is constrained. This happens for example in the function call
6751 -- and explicit dereference cases. In these cases, we have to get
6752 -- the length or range from the expression itself, making sure we
6753 -- do not evaluate it more than once.
6755 -- Here Ck_Node is the original expression, or more properly the
6756 -- result of applying Duplicate_Expr to the original tree,
6757 -- forcing the result to be a name.
6761 Ndims : constant Nat := Number_Dimensions (T_Typ);
6764 -- Build the condition for the explicit dereference case
6766 for Indx in 1 .. Ndims loop
6768 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
6775 -- For a conversion to an unconstrained array type, generate an
6776 -- Action to check that the bounds of the source value are within
6777 -- the constraints imposed by the target type (RM 4.6(38)). No
6778 -- check is needed for a conversion to an access to unconstrained
6779 -- array type, as 4.6(24.15/2) requires the designated subtypes
6780 -- of the two access types to statically match.
6782 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
6783 and then not Do_Access
6786 Opnd_Index : Node_Id;
6787 Targ_Index : Node_Id;
6788 Opnd_Range : Node_Id;
6791 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
6792 Targ_Index := First_Index (T_Typ);
6794 while Present (Opnd_Index) loop
6796 -- If the index is a range, use its bounds. If it is an
6797 -- entity (as will be the case if it is a named subtype
6798 -- or an itype created for a slice) retrieve its range.
6800 if Is_Entity_Name (Opnd_Index)
6801 and then Is_Type (Entity (Opnd_Index))
6803 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
6805 Opnd_Range := Opnd_Index;
6808 if Nkind (Opnd_Range) = N_Range then
6810 (Low_Bound (Opnd_Range), Etype (Targ_Index))
6813 (High_Bound (Opnd_Range), Etype (Targ_Index))
6817 -- If null range, no check needed
6820 Compile_Time_Known_Value (High_Bound (Opnd_Range))
6822 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
6824 Expr_Value (High_Bound (Opnd_Range)) <
6825 Expr_Value (Low_Bound (Opnd_Range))
6829 elsif Is_Out_Of_Range
6830 (Low_Bound (Opnd_Range), Etype (Targ_Index))
6833 (High_Bound (Opnd_Range), Etype (Targ_Index))
6836 (Compile_Time_Constraint_Error
6837 (Wnode, "value out of range of}?", T_Typ));
6843 (Opnd_Range, Etype (Targ_Index)));
6847 Next_Index (Opnd_Index);
6848 Next_Index (Targ_Index);
6855 -- Construct the test and insert into the tree
6857 if Present (Cond) then
6859 Cond := Guard_Access (Cond, Loc, Ck_Node);
6863 (Make_Raise_Constraint_Error (Loc,
6865 Reason => CE_Range_Check_Failed));
6869 end Selected_Range_Checks;
6871 -------------------------------
6872 -- Storage_Checks_Suppressed --
6873 -------------------------------
6875 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
6877 if Present (E) and then Checks_May_Be_Suppressed (E) then
6878 return Is_Check_Suppressed (E, Storage_Check);
6880 return Scope_Suppress (Storage_Check);
6882 end Storage_Checks_Suppressed;
6884 ---------------------------
6885 -- Tag_Checks_Suppressed --
6886 ---------------------------
6888 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
6891 if Kill_Tag_Checks (E) then
6893 elsif Checks_May_Be_Suppressed (E) then
6894 return Is_Check_Suppressed (E, Tag_Check);
6898 return Scope_Suppress (Tag_Check);
6899 end Tag_Checks_Suppressed;
6901 --------------------------
6902 -- Validity_Check_Range --
6903 --------------------------
6905 procedure Validity_Check_Range (N : Node_Id) is
6907 if Validity_Checks_On and Validity_Check_Operands then
6908 if Nkind (N) = N_Range then
6909 Ensure_Valid (Low_Bound (N));
6910 Ensure_Valid (High_Bound (N));
6913 end Validity_Check_Range;
6915 --------------------------------
6916 -- Validity_Checks_Suppressed --
6917 --------------------------------
6919 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
6921 if Present (E) and then Checks_May_Be_Suppressed (E) then
6922 return Is_Check_Suppressed (E, Validity_Check);
6924 return Scope_Suppress (Validity_Check);
6926 end Validity_Checks_Suppressed;