1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2014, 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 Casing; use Casing;
28 with Debug; use Debug;
29 with Einfo; use Einfo;
30 with Elists; use Elists;
31 with Eval_Fat; use Eval_Fat;
32 with Exp_Ch11; use Exp_Ch11;
33 with Exp_Ch2; use Exp_Ch2;
34 with Exp_Ch4; use Exp_Ch4;
35 with Exp_Pakd; use Exp_Pakd;
36 with Exp_Util; use Exp_Util;
37 with Expander; use Expander;
38 with Freeze; use Freeze;
40 with Nlists; use Nlists;
41 with Nmake; use Nmake;
43 with Output; use Output;
44 with Restrict; use Restrict;
45 with Rident; use Rident;
46 with Rtsfind; use Rtsfind;
48 with Sem_Aux; use Sem_Aux;
49 with Sem_Ch3; use Sem_Ch3;
50 with Sem_Ch8; use Sem_Ch8;
51 with Sem_Eval; use Sem_Eval;
52 with Sem_Res; use Sem_Res;
53 with Sem_Util; use Sem_Util;
54 with Sem_Warn; use Sem_Warn;
55 with Sinfo; use Sinfo;
56 with Sinput; use Sinput;
57 with Snames; use Snames;
58 with Sprint; use Sprint;
59 with Stand; use Stand;
60 with Stringt; use Stringt;
61 with Targparm; use Targparm;
62 with Tbuild; use Tbuild;
63 with Ttypes; use Ttypes;
64 with Validsw; use Validsw;
66 package body Checks is
68 -- General note: many of these routines are concerned with generating
69 -- checking code to make sure that constraint error is raised at runtime.
70 -- Clearly this code is only needed if the expander is active, since
71 -- otherwise we will not be generating code or going into the runtime
74 -- We therefore disconnect most of these checks if the expander is
75 -- inactive. This has the additional benefit that we do not need to
76 -- worry about the tree being messed up by previous errors (since errors
77 -- turn off expansion anyway).
79 -- There are a few exceptions to the above rule. For instance routines
80 -- such as Apply_Scalar_Range_Check that do not insert any code can be
81 -- safely called even when the Expander is inactive (but Errors_Detected
82 -- is 0). The benefit of executing this code when expansion is off, is
83 -- the ability to emit constraint error warning for static expressions
84 -- even when we are not generating code.
86 -- The above is modified in gnatprove mode to ensure that proper check
87 -- flags are always placed, even if expansion is off.
89 -------------------------------------
90 -- Suppression of Redundant Checks --
91 -------------------------------------
93 -- This unit implements a limited circuit for removal of redundant
94 -- checks. The processing is based on a tracing of simple sequential
95 -- flow. For any sequence of statements, we save expressions that are
96 -- marked to be checked, and then if the same expression appears later
97 -- with the same check, then under certain circumstances, the second
98 -- check can be suppressed.
100 -- Basically, we can suppress the check if we know for certain that
101 -- the previous expression has been elaborated (together with its
102 -- check), and we know that the exception frame is the same, and that
103 -- nothing has happened to change the result of the exception.
105 -- Let us examine each of these three conditions in turn to describe
106 -- how we ensure that this condition is met.
108 -- First, we need to know for certain that the previous expression has
109 -- been executed. This is done principally by the mechanism of calling
110 -- Conditional_Statements_Begin at the start of any statement sequence
111 -- and Conditional_Statements_End at the end. The End call causes all
112 -- checks remembered since the Begin call to be discarded. This does
113 -- miss a few cases, notably the case of a nested BEGIN-END block with
114 -- no exception handlers. But the important thing is to be conservative.
115 -- The other protection is that all checks are discarded if a label
116 -- is encountered, since then the assumption of sequential execution
117 -- is violated, and we don't know enough about the flow.
119 -- Second, we need to know that the exception frame is the same. We
120 -- do this by killing all remembered checks when we enter a new frame.
121 -- Again, that's over-conservative, but generally the cases we can help
122 -- with are pretty local anyway (like the body of a loop for example).
124 -- Third, we must be sure to forget any checks which are no longer valid.
125 -- This is done by two mechanisms, first the Kill_Checks_Variable call is
126 -- used to note any changes to local variables. We only attempt to deal
127 -- with checks involving local variables, so we do not need to worry
128 -- about global variables. Second, a call to any non-global procedure
129 -- causes us to abandon all stored checks, since such a all may affect
130 -- the values of any local variables.
132 -- The following define the data structures used to deal with remembering
133 -- checks so that redundant checks can be eliminated as described above.
135 -- Right now, the only expressions that we deal with are of the form of
136 -- simple local objects (either declared locally, or IN parameters) or
137 -- such objects plus/minus a compile time known constant. We can do
138 -- more later on if it seems worthwhile, but this catches many simple
139 -- cases in practice.
141 -- The following record type reflects a single saved check. An entry
142 -- is made in the stack of saved checks if and only if the expression
143 -- has been elaborated with the indicated checks.
145 type Saved_Check is record
147 -- Set True if entry is killed by Kill_Checks
150 -- The entity involved in the expression that is checked
153 -- A compile time value indicating the result of adding or
154 -- subtracting a compile time value. This value is to be
155 -- added to the value of the Entity. A value of zero is
156 -- used for the case of a simple entity reference.
158 Check_Type : Character;
159 -- This is set to 'R' for a range check (in which case Target_Type
160 -- is set to the target type for the range check) or to 'O' for an
161 -- overflow check (in which case Target_Type is set to Empty).
163 Target_Type : Entity_Id;
164 -- Used only if Do_Range_Check is set. Records the target type for
165 -- the check. We need this, because a check is a duplicate only if
166 -- it has the same target type (or more accurately one with a
167 -- range that is smaller or equal to the stored target type of a
171 -- The following table keeps track of saved checks. Rather than use an
172 -- extensible table. We just use a table of fixed size, and we discard
173 -- any saved checks that do not fit. That's very unlikely to happen and
174 -- this is only an optimization in any case.
176 Saved_Checks : array (Int range 1 .. 200) of Saved_Check;
177 -- Array of saved checks
179 Num_Saved_Checks : Nat := 0;
180 -- Number of saved checks
182 -- The following stack keeps track of statement ranges. It is treated
183 -- as a stack. When Conditional_Statements_Begin is called, an entry
184 -- is pushed onto this stack containing the value of Num_Saved_Checks
185 -- at the time of the call. Then when Conditional_Statements_End is
186 -- called, this value is popped off and used to reset Num_Saved_Checks.
188 -- Note: again, this is a fixed length stack with a size that should
189 -- always be fine. If the value of the stack pointer goes above the
190 -- limit, then we just forget all saved checks.
192 Saved_Checks_Stack : array (Int range 1 .. 100) of Nat;
193 Saved_Checks_TOS : Nat := 0;
195 -----------------------
196 -- Local Subprograms --
197 -----------------------
199 procedure Apply_Arithmetic_Overflow_Strict (N : Node_Id);
200 -- Used to apply arithmetic overflow checks for all cases except operators
201 -- on signed arithmetic types in MINIMIZED/ELIMINATED case (for which we
202 -- call Apply_Arithmetic_Overflow_Minimized_Eliminated below). N can be a
203 -- signed integer arithmetic operator (but not an if or case expression).
204 -- It is also called for types other than signed integers.
206 procedure Apply_Arithmetic_Overflow_Minimized_Eliminated (Op : Node_Id);
207 -- Used to apply arithmetic overflow checks for the case where the overflow
208 -- checking mode is MINIMIZED or ELIMINATED and we have a signed integer
209 -- arithmetic op (which includes the case of if and case expressions). Note
210 -- that Do_Overflow_Check may or may not be set for node Op. In these modes
211 -- we have work to do even if overflow checking is suppressed.
213 procedure Apply_Division_Check
218 -- N is an N_Op_Div, N_Op_Rem, or N_Op_Mod node. This routine applies
219 -- division checks as required if the Do_Division_Check flag is set.
220 -- Rlo and Rhi give the possible range of the right operand, these values
221 -- can be referenced and trusted only if ROK is set True.
223 procedure Apply_Float_Conversion_Check
225 Target_Typ : Entity_Id);
226 -- The checks on a conversion from a floating-point type to an integer
227 -- type are delicate. They have to be performed before conversion, they
228 -- have to raise an exception when the operand is a NaN, and rounding must
229 -- be taken into account to determine the safe bounds of the operand.
231 procedure Apply_Selected_Length_Checks
233 Target_Typ : Entity_Id;
234 Source_Typ : Entity_Id;
235 Do_Static : Boolean);
236 -- This is the subprogram that does all the work for Apply_Length_Check
237 -- and Apply_Static_Length_Check. Expr, Target_Typ and Source_Typ are as
238 -- described for the above routines. The Do_Static flag indicates that
239 -- only a static check is to be done.
241 procedure Apply_Selected_Range_Checks
243 Target_Typ : Entity_Id;
244 Source_Typ : Entity_Id;
245 Do_Static : Boolean);
246 -- This is the subprogram that does all the work for Apply_Range_Check.
247 -- Expr, Target_Typ and Source_Typ are as described for the above
248 -- routine. The Do_Static flag indicates that only a static check is
251 type Check_Type is new Check_Id range Access_Check .. Division_Check;
252 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean;
253 -- This function is used to see if an access or division by zero check is
254 -- needed. The check is to be applied to a single variable appearing in the
255 -- source, and N is the node for the reference. If N is not of this form,
256 -- True is returned with no further processing. If N is of the right form,
257 -- then further processing determines if the given Check is needed.
259 -- The particular circuit is to see if we have the case of a check that is
260 -- not needed because it appears in the right operand of a short circuited
261 -- conditional where the left operand guards the check. For example:
263 -- if Var = 0 or else Q / Var > 12 then
267 -- In this example, the division check is not required. At the same time
268 -- we can issue warnings for suspicious use of non-short-circuited forms,
271 -- if Var = 0 or Q / Var > 12 then
277 Check_Type : Character;
278 Target_Type : Entity_Id;
279 Entry_OK : out Boolean;
283 -- This routine is used by Enable_Range_Check and Enable_Overflow_Check
284 -- to see if a check is of the form for optimization, and if so, to see
285 -- if it has already been performed. Expr is the expression to check,
286 -- and Check_Type is 'R' for a range check, 'O' for an overflow check.
287 -- Target_Type is the target type for a range check, and Empty for an
288 -- overflow check. If the entry is not of the form for optimization,
289 -- then Entry_OK is set to False, and the remaining out parameters
290 -- are undefined. If the entry is OK, then Ent/Ofs are set to the
291 -- entity and offset from the expression. Check_Num is the number of
292 -- a matching saved entry in Saved_Checks, or zero if no such entry
295 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id;
296 -- If a discriminal is used in constraining a prival, Return reference
297 -- to the discriminal of the protected body (which renames the parameter
298 -- of the enclosing protected operation). This clumsy transformation is
299 -- needed because privals are created too late and their actual subtypes
300 -- are not available when analysing the bodies of the protected operations.
301 -- This function is called whenever the bound is an entity and the scope
302 -- indicates a protected operation. If the bound is an in-parameter of
303 -- a protected operation that is not a prival, the function returns the
305 -- To be cleaned up???
307 function Guard_Access
310 Ck_Node : Node_Id) return Node_Id;
311 -- In the access type case, guard the test with a test to ensure
312 -- that the access value is non-null, since the checks do not
313 -- not apply to null access values.
315 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr);
316 -- Called by Apply_{Length,Range}_Checks to rewrite the tree with the
317 -- Constraint_Error node.
319 function Is_Signed_Integer_Arithmetic_Op (N : Node_Id) return Boolean;
320 -- Returns True if node N is for an arithmetic operation with signed
321 -- integer operands. This includes unary and binary operators, and also
322 -- if and case expression nodes where the dependent expressions are of
323 -- a signed integer type. These are the kinds of nodes for which special
324 -- handling applies in MINIMIZED or ELIMINATED overflow checking mode.
326 function Range_Or_Validity_Checks_Suppressed
327 (Expr : Node_Id) return Boolean;
328 -- Returns True if either range or validity checks or both are suppressed
329 -- for the type of the given expression, or, if the expression is the name
330 -- of an entity, if these checks are suppressed for the entity.
332 function Selected_Length_Checks
334 Target_Typ : Entity_Id;
335 Source_Typ : Entity_Id;
336 Warn_Node : Node_Id) return Check_Result;
337 -- Like Apply_Selected_Length_Checks, except it doesn't modify
338 -- anything, just returns a list of nodes as described in the spec of
339 -- this package for the Range_Check function.
341 function Selected_Range_Checks
343 Target_Typ : Entity_Id;
344 Source_Typ : Entity_Id;
345 Warn_Node : Node_Id) return Check_Result;
346 -- Like Apply_Selected_Range_Checks, except it doesn't modify anything,
347 -- just returns a list of nodes as described in the spec of this package
348 -- for the Range_Check function.
350 ------------------------------
351 -- Access_Checks_Suppressed --
352 ------------------------------
354 function Access_Checks_Suppressed (E : Entity_Id) return Boolean is
356 if Present (E) and then Checks_May_Be_Suppressed (E) then
357 return Is_Check_Suppressed (E, Access_Check);
359 return Scope_Suppress.Suppress (Access_Check);
361 end Access_Checks_Suppressed;
363 -------------------------------------
364 -- Accessibility_Checks_Suppressed --
365 -------------------------------------
367 function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean is
369 if Present (E) and then Checks_May_Be_Suppressed (E) then
370 return Is_Check_Suppressed (E, Accessibility_Check);
372 return Scope_Suppress.Suppress (Accessibility_Check);
374 end Accessibility_Checks_Suppressed;
376 -----------------------------
377 -- Activate_Division_Check --
378 -----------------------------
380 procedure Activate_Division_Check (N : Node_Id) is
382 Set_Do_Division_Check (N, True);
383 Possible_Local_Raise (N, Standard_Constraint_Error);
384 end Activate_Division_Check;
386 -----------------------------
387 -- Activate_Overflow_Check --
388 -----------------------------
390 procedure Activate_Overflow_Check (N : Node_Id) is
392 -- Nothing to do for unconstrained floating-point types (the test for
393 -- Etype (N) being present seems necessary in some cases, should be
394 -- tracked down, but for now just ignore the check in this case ???)
396 if Present (Etype (N))
397 and then Is_Floating_Point_Type (Etype (N))
398 and then not Is_Constrained (Etype (N))
400 -- But do the check after all if float overflow checking enforced
402 and then not Check_Float_Overflow
407 -- Nothing to do for Rem/Mod/Plus (overflow not possible)
409 if Nkind_In (N, N_Op_Rem, N_Op_Mod, N_Op_Plus) then
413 -- Otherwise set the flag
415 Set_Do_Overflow_Check (N, True);
416 Possible_Local_Raise (N, Standard_Constraint_Error);
417 end Activate_Overflow_Check;
419 --------------------------
420 -- Activate_Range_Check --
421 --------------------------
423 procedure Activate_Range_Check (N : Node_Id) is
425 Set_Do_Range_Check (N, True);
426 Possible_Local_Raise (N, Standard_Constraint_Error);
427 end Activate_Range_Check;
429 ---------------------------------
430 -- Alignment_Checks_Suppressed --
431 ---------------------------------
433 function Alignment_Checks_Suppressed (E : Entity_Id) return Boolean is
435 if Present (E) and then Checks_May_Be_Suppressed (E) then
436 return Is_Check_Suppressed (E, Alignment_Check);
438 return Scope_Suppress.Suppress (Alignment_Check);
440 end Alignment_Checks_Suppressed;
442 ----------------------------------
443 -- Allocation_Checks_Suppressed --
444 ----------------------------------
446 -- Note: at the current time there are no calls to this function, because
447 -- the relevant check is in the run-time, so it is not a check that the
448 -- compiler can suppress anyway, but we still have to recognize the check
449 -- name Allocation_Check since it is part of the standard.
451 function Allocation_Checks_Suppressed (E : Entity_Id) return Boolean is
453 if Present (E) and then Checks_May_Be_Suppressed (E) then
454 return Is_Check_Suppressed (E, Allocation_Check);
456 return Scope_Suppress.Suppress (Allocation_Check);
458 end Allocation_Checks_Suppressed;
460 -------------------------
461 -- Append_Range_Checks --
462 -------------------------
464 procedure Append_Range_Checks
465 (Checks : Check_Result;
467 Suppress_Typ : Entity_Id;
468 Static_Sloc : Source_Ptr;
471 Internal_Flag_Node : constant Node_Id := Flag_Node;
472 Internal_Static_Sloc : constant Source_Ptr := Static_Sloc;
474 Checks_On : constant Boolean :=
475 (not Index_Checks_Suppressed (Suppress_Typ))
476 or else (not Range_Checks_Suppressed (Suppress_Typ));
479 -- For now we just return if Checks_On is false, however this should
480 -- be enhanced to check for an always True value in the condition
481 -- and to generate a compilation warning???
483 if not Checks_On then
488 exit when No (Checks (J));
490 if Nkind (Checks (J)) = N_Raise_Constraint_Error
491 and then Present (Condition (Checks (J)))
493 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
494 Append_To (Stmts, Checks (J));
495 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
501 Make_Raise_Constraint_Error (Internal_Static_Sloc,
502 Reason => CE_Range_Check_Failed));
505 end Append_Range_Checks;
507 ------------------------
508 -- Apply_Access_Check --
509 ------------------------
511 procedure Apply_Access_Check (N : Node_Id) is
512 P : constant Node_Id := Prefix (N);
515 -- We do not need checks if we are not generating code (i.e. the
516 -- expander is not active). This is not just an optimization, there
517 -- are cases (e.g. with pragma Debug) where generating the checks
518 -- can cause real trouble).
520 if not Expander_Active then
524 -- No check if short circuiting makes check unnecessary
526 if not Check_Needed (P, Access_Check) then
530 -- No check if accessing the Offset_To_Top component of a dispatch
531 -- table. They are safe by construction.
533 if Tagged_Type_Expansion
534 and then Present (Etype (P))
535 and then RTU_Loaded (Ada_Tags)
536 and then RTE_Available (RE_Offset_To_Top_Ptr)
537 and then Etype (P) = RTE (RE_Offset_To_Top_Ptr)
542 -- Otherwise go ahead and install the check
544 Install_Null_Excluding_Check (P);
545 end Apply_Access_Check;
547 -------------------------------
548 -- Apply_Accessibility_Check --
549 -------------------------------
551 procedure Apply_Accessibility_Check
554 Insert_Node : Node_Id)
556 Loc : constant Source_Ptr := Sloc (N);
557 Param_Ent : Entity_Id := Param_Entity (N);
558 Param_Level : Node_Id;
559 Type_Level : Node_Id;
562 if Ada_Version >= Ada_2012
563 and then not Present (Param_Ent)
564 and then Is_Entity_Name (N)
565 and then Ekind_In (Entity (N), E_Constant, E_Variable)
566 and then Present (Effective_Extra_Accessibility (Entity (N)))
568 Param_Ent := Entity (N);
569 while Present (Renamed_Object (Param_Ent)) loop
571 -- Renamed_Object must return an Entity_Name here
572 -- because of preceding "Present (E_E_A (...))" test.
574 Param_Ent := Entity (Renamed_Object (Param_Ent));
578 if Inside_A_Generic then
581 -- Only apply the run-time check if the access parameter has an
582 -- associated extra access level parameter and when the level of the
583 -- type is less deep than the level of the access parameter, and
584 -- accessibility checks are not suppressed.
586 elsif Present (Param_Ent)
587 and then Present (Extra_Accessibility (Param_Ent))
588 and then UI_Gt (Object_Access_Level (N),
589 Deepest_Type_Access_Level (Typ))
590 and then not Accessibility_Checks_Suppressed (Param_Ent)
591 and then not Accessibility_Checks_Suppressed (Typ)
594 New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc);
597 Make_Integer_Literal (Loc, Deepest_Type_Access_Level (Typ));
599 -- Raise Program_Error if the accessibility level of the access
600 -- parameter is deeper than the level of the target access type.
602 Insert_Action (Insert_Node,
603 Make_Raise_Program_Error (Loc,
606 Left_Opnd => Param_Level,
607 Right_Opnd => Type_Level),
608 Reason => PE_Accessibility_Check_Failed));
610 Analyze_And_Resolve (N);
612 end Apply_Accessibility_Check;
614 --------------------------------
615 -- Apply_Address_Clause_Check --
616 --------------------------------
618 procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is
619 pragma Assert (Nkind (N) = N_Freeze_Entity);
621 AC : constant Node_Id := Address_Clause (E);
622 Loc : constant Source_Ptr := Sloc (AC);
623 Typ : constant Entity_Id := Etype (E);
624 Aexp : constant Node_Id := Expression (AC);
627 -- Address expression (not necessarily the same as Aexp, for example
628 -- when Aexp is a reference to a constant, in which case Expr gets
629 -- reset to reference the value expression of the constant).
631 procedure Compile_Time_Bad_Alignment;
632 -- Post error warnings when alignment is known to be incompatible. Note
633 -- that we do not go as far as inserting a raise of Program_Error since
634 -- this is an erroneous case, and it may happen that we are lucky and an
635 -- underaligned address turns out to be OK after all.
637 --------------------------------
638 -- Compile_Time_Bad_Alignment --
639 --------------------------------
641 procedure Compile_Time_Bad_Alignment is
643 if Address_Clause_Overlay_Warnings then
645 ("?o?specified address for& may be inconsistent with alignment",
648 ("\?o?program execution may be erroneous (RM 13.3(27))",
650 Set_Address_Warning_Posted (AC);
652 end Compile_Time_Bad_Alignment;
654 -- Start of processing for Apply_Address_Clause_Check
657 -- See if alignment check needed. Note that we never need a check if the
658 -- maximum alignment is one, since the check will always succeed.
660 -- Note: we do not check for checks suppressed here, since that check
661 -- was done in Sem_Ch13 when the address clause was processed. We are
662 -- only called if checks were not suppressed. The reason for this is
663 -- that we have to delay the call to Apply_Alignment_Check till freeze
664 -- time (so that all types etc are elaborated), but we have to check
665 -- the status of check suppressing at the point of the address clause.
668 or else not Check_Address_Alignment (AC)
669 or else Maximum_Alignment = 1
674 -- Obtain expression from address clause
676 Expr := Expression (AC);
678 -- The following loop digs for the real expression to use in the check
681 -- For constant, get constant expression
683 if Is_Entity_Name (Expr)
684 and then Ekind (Entity (Expr)) = E_Constant
686 Expr := Constant_Value (Entity (Expr));
688 -- For unchecked conversion, get result to convert
690 elsif Nkind (Expr) = N_Unchecked_Type_Conversion then
691 Expr := Expression (Expr);
693 -- For (common case) of To_Address call, get argument
695 elsif Nkind (Expr) = N_Function_Call
696 and then Is_Entity_Name (Name (Expr))
697 and then Is_RTE (Entity (Name (Expr)), RE_To_Address)
699 Expr := First (Parameter_Associations (Expr));
701 if Nkind (Expr) = N_Parameter_Association then
702 Expr := Explicit_Actual_Parameter (Expr);
705 -- We finally have the real expression
712 -- See if we know that Expr has a bad alignment at compile time
714 if Compile_Time_Known_Value (Expr)
715 and then (Known_Alignment (E) or else Known_Alignment (Typ))
718 AL : Uint := Alignment (Typ);
721 -- The object alignment might be more restrictive than the
724 if Known_Alignment (E) then
728 if Expr_Value (Expr) mod AL /= 0 then
729 Compile_Time_Bad_Alignment;
735 -- If the expression has the form X'Address, then we can find out if
736 -- the object X has an alignment that is compatible with the object E.
737 -- If it hasn't or we don't know, we defer issuing the warning until
738 -- the end of the compilation to take into account back end annotations.
740 elsif Nkind (Expr) = N_Attribute_Reference
741 and then Attribute_Name (Expr) = Name_Address
742 and then Has_Compatible_Alignment (E, Prefix (Expr)) = Known_Compatible
747 -- Here we do not know if the value is acceptable. Strictly we don't
748 -- have to do anything, since if the alignment is bad, we have an
749 -- erroneous program. However we are allowed to check for erroneous
750 -- conditions and we decide to do this by default if the check is not
753 -- However, don't do the check if elaboration code is unwanted
755 if Restriction_Active (No_Elaboration_Code) then
758 -- Generate a check to raise PE if alignment may be inappropriate
761 -- If the original expression is a non-static constant, use the
762 -- name of the constant itself rather than duplicating its
763 -- defining expression, which was extracted above.
765 -- Note: Expr is empty if the address-clause is applied to in-mode
766 -- actuals (allowed by 13.1(22)).
768 if not Present (Expr)
770 (Is_Entity_Name (Expression (AC))
771 and then Ekind (Entity (Expression (AC))) = E_Constant
772 and then Nkind (Parent (Entity (Expression (AC))))
773 = N_Object_Declaration)
775 Expr := New_Copy_Tree (Expression (AC));
777 Remove_Side_Effects (Expr);
780 if No (Actions (N)) then
781 Set_Actions (N, New_List);
784 Prepend_To (Actions (N),
785 Make_Raise_Program_Error (Loc,
792 (RTE (RE_Integer_Address), Expr),
794 Make_Attribute_Reference (Loc,
795 Prefix => New_Occurrence_Of (E, Loc),
796 Attribute_Name => Name_Alignment)),
797 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
798 Reason => PE_Misaligned_Address_Value));
800 Warning_Msg := No_Error_Msg;
801 Analyze (First (Actions (N)), Suppress => All_Checks);
803 -- If the address clause generated a warning message (for example,
804 -- from Warn_On_Non_Local_Exception mode with the active restriction
805 -- No_Exception_Propagation).
807 if Warning_Msg /= No_Error_Msg then
809 -- If the expression has a known at compile time value, then
810 -- once we know the alignment of the type, we can check if the
811 -- exception will be raised or not, and if not, we don't need
812 -- the warning so we will kill the warning later on.
814 if Compile_Time_Known_Value (Expr) then
815 Alignment_Warnings.Append
816 ((E => E, A => Expr_Value (Expr), W => Warning_Msg));
819 -- Add explanation of the warning that is generated by the check
822 ("\address value may be incompatible with alignment "
823 & "of object?X?", AC);
830 -- If we have some missing run time component in configurable run time
831 -- mode then just skip the check (it is not required in any case).
833 when RE_Not_Available =>
835 end Apply_Address_Clause_Check;
837 -------------------------------------
838 -- Apply_Arithmetic_Overflow_Check --
839 -------------------------------------
841 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
843 -- Use old routine in almost all cases (the only case we are treating
844 -- specially is the case of a signed integer arithmetic op with the
845 -- overflow checking mode set to MINIMIZED or ELIMINATED).
847 if Overflow_Check_Mode = Strict
848 or else not Is_Signed_Integer_Arithmetic_Op (N)
850 Apply_Arithmetic_Overflow_Strict (N);
852 -- Otherwise use the new routine for the case of a signed integer
853 -- arithmetic op, with Do_Overflow_Check set to True, and the checking
854 -- mode is MINIMIZED or ELIMINATED.
857 Apply_Arithmetic_Overflow_Minimized_Eliminated (N);
859 end Apply_Arithmetic_Overflow_Check;
861 --------------------------------------
862 -- Apply_Arithmetic_Overflow_Strict --
863 --------------------------------------
865 -- This routine is called only if the type is an integer type, and a
866 -- software arithmetic overflow check may be needed for op (add, subtract,
867 -- or multiply). This check is performed only if Software_Overflow_Checking
868 -- is enabled and Do_Overflow_Check is set. In this case we expand the
869 -- operation into a more complex sequence of tests that ensures that
870 -- overflow is properly caught.
872 -- This is used in CHECKED modes. It is identical to the code for this
873 -- cases before the big overflow earthquake, thus ensuring that in this
874 -- modes we have compatible behavior (and reliability) to what was there
875 -- before. It is also called for types other than signed integers, and if
876 -- the Do_Overflow_Check flag is off.
878 -- Note: we also call this routine if we decide in the MINIMIZED case
879 -- to give up and just generate an overflow check without any fuss.
881 procedure Apply_Arithmetic_Overflow_Strict (N : Node_Id) is
882 Loc : constant Source_Ptr := Sloc (N);
883 Typ : constant Entity_Id := Etype (N);
884 Rtyp : constant Entity_Id := Root_Type (Typ);
887 -- Nothing to do if Do_Overflow_Check not set or overflow checks
890 if not Do_Overflow_Check (N) then
894 -- An interesting special case. If the arithmetic operation appears as
895 -- the operand of a type conversion:
899 -- and all the following conditions apply:
901 -- arithmetic operation is for a signed integer type
902 -- target type type1 is a static integer subtype
903 -- range of x and y are both included in the range of type1
904 -- range of x op y is included in the range of type1
905 -- size of type1 is at least twice the result size of op
907 -- then we don't do an overflow check in any case, instead we transform
908 -- the operation so that we end up with:
910 -- type1 (type1 (x) op type1 (y))
912 -- This avoids intermediate overflow before the conversion. It is
913 -- explicitly permitted by RM 3.5.4(24):
915 -- For the execution of a predefined operation of a signed integer
916 -- type, the implementation need not raise Constraint_Error if the
917 -- result is outside the base range of the type, so long as the
918 -- correct result is produced.
920 -- It's hard to imagine that any programmer counts on the exception
921 -- being raised in this case, and in any case it's wrong coding to
922 -- have this expectation, given the RM permission. Furthermore, other
923 -- Ada compilers do allow such out of range results.
925 -- Note that we do this transformation even if overflow checking is
926 -- off, since this is precisely about giving the "right" result and
927 -- avoiding the need for an overflow check.
929 -- Note: this circuit is partially redundant with respect to the similar
930 -- processing in Exp_Ch4.Expand_N_Type_Conversion, but the latter deals
931 -- with cases that do not come through here. We still need the following
932 -- processing even with the Exp_Ch4 code in place, since we want to be
933 -- sure not to generate the arithmetic overflow check in these cases
934 -- (Exp_Ch4 would have a hard time removing them once generated).
936 if Is_Signed_Integer_Type (Typ)
937 and then Nkind (Parent (N)) = N_Type_Conversion
939 Conversion_Optimization : declare
940 Target_Type : constant Entity_Id :=
941 Base_Type (Entity (Subtype_Mark (Parent (N))));
955 if Is_Integer_Type (Target_Type)
956 and then RM_Size (Root_Type (Target_Type)) >= 2 * RM_Size (Rtyp)
958 Tlo := Expr_Value (Type_Low_Bound (Target_Type));
959 Thi := Expr_Value (Type_High_Bound (Target_Type));
962 (Left_Opnd (N), LOK, Llo, Lhi, Assume_Valid => True);
964 (Right_Opnd (N), ROK, Rlo, Rhi, Assume_Valid => True);
967 and then Tlo <= Llo and then Lhi <= Thi
968 and then Tlo <= Rlo and then Rhi <= Thi
970 Determine_Range (N, VOK, Vlo, Vhi, Assume_Valid => True);
972 if VOK and then Tlo <= Vlo and then Vhi <= Thi then
973 Rewrite (Left_Opnd (N),
974 Make_Type_Conversion (Loc,
975 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
976 Expression => Relocate_Node (Left_Opnd (N))));
978 Rewrite (Right_Opnd (N),
979 Make_Type_Conversion (Loc,
980 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
981 Expression => Relocate_Node (Right_Opnd (N))));
983 -- Rewrite the conversion operand so that the original
984 -- node is retained, in order to avoid the warning for
985 -- redundant conversions in Resolve_Type_Conversion.
987 Rewrite (N, Relocate_Node (N));
989 Set_Etype (N, Target_Type);
991 Analyze_And_Resolve (Left_Opnd (N), Target_Type);
992 Analyze_And_Resolve (Right_Opnd (N), Target_Type);
994 -- Given that the target type is twice the size of the
995 -- source type, overflow is now impossible, so we can
996 -- safely kill the overflow check and return.
998 Set_Do_Overflow_Check (N, False);
1003 end Conversion_Optimization;
1006 -- Now see if an overflow check is required
1009 Siz : constant Int := UI_To_Int (Esize (Rtyp));
1010 Dsiz : constant Int := Siz * 2;
1017 -- Skip check if back end does overflow checks, or the overflow flag
1018 -- is not set anyway, or we are not doing code expansion, or the
1019 -- parent node is a type conversion whose operand is an arithmetic
1020 -- operation on signed integers on which the expander can promote
1021 -- later the operands to type Integer (see Expand_N_Type_Conversion).
1023 -- Special case CLI target, where arithmetic overflow checks can be
1024 -- performed for integer and long_integer
1026 if Backend_Overflow_Checks_On_Target
1027 or else not Do_Overflow_Check (N)
1028 or else not Expander_Active
1029 or else (Present (Parent (N))
1030 and then Nkind (Parent (N)) = N_Type_Conversion
1031 and then Integer_Promotion_Possible (Parent (N)))
1033 (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
1038 -- Otherwise, generate the full general code for front end overflow
1039 -- detection, which works by doing arithmetic in a larger type:
1045 -- Typ (Checktyp (x) op Checktyp (y));
1047 -- where Typ is the type of the original expression, and Checktyp is
1048 -- an integer type of sufficient length to hold the largest possible
1051 -- If the size of check type exceeds the size of Long_Long_Integer,
1052 -- we use a different approach, expanding to:
1054 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
1056 -- where xxx is Add, Multiply or Subtract as appropriate
1058 -- Find check type if one exists
1060 if Dsiz <= Standard_Integer_Size then
1061 Ctyp := Standard_Integer;
1063 elsif Dsiz <= Standard_Long_Long_Integer_Size then
1064 Ctyp := Standard_Long_Long_Integer;
1066 -- No check type exists, use runtime call
1069 if Nkind (N) = N_Op_Add then
1070 Cent := RE_Add_With_Ovflo_Check;
1072 elsif Nkind (N) = N_Op_Multiply then
1073 Cent := RE_Multiply_With_Ovflo_Check;
1076 pragma Assert (Nkind (N) = N_Op_Subtract);
1077 Cent := RE_Subtract_With_Ovflo_Check;
1082 Make_Function_Call (Loc,
1083 Name => New_Occurrence_Of (RTE (Cent), Loc),
1084 Parameter_Associations => New_List (
1085 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
1086 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
1088 Analyze_And_Resolve (N, Typ);
1092 -- If we fall through, we have the case where we do the arithmetic
1093 -- in the next higher type and get the check by conversion. In these
1094 -- cases Ctyp is set to the type to be used as the check type.
1096 Opnod := Relocate_Node (N);
1098 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
1101 Set_Etype (Opnd, Ctyp);
1102 Set_Analyzed (Opnd, True);
1103 Set_Left_Opnd (Opnod, Opnd);
1105 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
1108 Set_Etype (Opnd, Ctyp);
1109 Set_Analyzed (Opnd, True);
1110 Set_Right_Opnd (Opnod, Opnd);
1112 -- The type of the operation changes to the base type of the check
1113 -- type, and we reset the overflow check indication, since clearly no
1114 -- overflow is possible now that we are using a double length type.
1115 -- We also set the Analyzed flag to avoid a recursive attempt to
1118 Set_Etype (Opnod, Base_Type (Ctyp));
1119 Set_Do_Overflow_Check (Opnod, False);
1120 Set_Analyzed (Opnod, True);
1122 -- Now build the outer conversion
1124 Opnd := OK_Convert_To (Typ, Opnod);
1126 Set_Etype (Opnd, Typ);
1128 -- In the discrete type case, we directly generate the range check
1129 -- for the outer operand. This range check will implement the
1130 -- required overflow check.
1132 if Is_Discrete_Type (Typ) then
1134 Generate_Range_Check
1135 (Expression (N), Typ, CE_Overflow_Check_Failed);
1137 -- For other types, we enable overflow checking on the conversion,
1138 -- after setting the node as analyzed to prevent recursive attempts
1139 -- to expand the conversion node.
1142 Set_Analyzed (Opnd, True);
1143 Enable_Overflow_Check (Opnd);
1148 when RE_Not_Available =>
1151 end Apply_Arithmetic_Overflow_Strict;
1153 ----------------------------------------------------
1154 -- Apply_Arithmetic_Overflow_Minimized_Eliminated --
1155 ----------------------------------------------------
1157 procedure Apply_Arithmetic_Overflow_Minimized_Eliminated (Op : Node_Id) is
1158 pragma Assert (Is_Signed_Integer_Arithmetic_Op (Op));
1160 Loc : constant Source_Ptr := Sloc (Op);
1161 P : constant Node_Id := Parent (Op);
1163 LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer);
1164 -- Operands and results are of this type when we convert
1166 Result_Type : constant Entity_Id := Etype (Op);
1167 -- Original result type
1169 Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
1170 pragma Assert (Check_Mode in Minimized_Or_Eliminated);
1173 -- Ranges of values for result
1176 -- Nothing to do if our parent is one of the following:
1178 -- Another signed integer arithmetic op
1179 -- A membership operation
1180 -- A comparison operation
1182 -- In all these cases, we will process at the higher level (and then
1183 -- this node will be processed during the downwards recursion that
1184 -- is part of the processing in Minimize_Eliminate_Overflows).
1186 if Is_Signed_Integer_Arithmetic_Op (P)
1187 or else Nkind (P) in N_Membership_Test
1188 or else Nkind (P) in N_Op_Compare
1190 -- This is also true for an alternative in a case expression
1192 or else Nkind (P) = N_Case_Expression_Alternative
1194 -- This is also true for a range operand in a membership test
1196 or else (Nkind (P) = N_Range
1197 and then Nkind (Parent (P)) in N_Membership_Test)
1202 -- Otherwise, we have a top level arithmetic operation node, and this
1203 -- is where we commence the special processing for MINIMIZED/ELIMINATED
1204 -- modes. This is the case where we tell the machinery not to move into
1205 -- Bignum mode at this top level (of course the top level operation
1206 -- will still be in Bignum mode if either of its operands are of type
1209 Minimize_Eliminate_Overflows (Op, Lo, Hi, Top_Level => True);
1211 -- That call may but does not necessarily change the result type of Op.
1212 -- It is the job of this routine to undo such changes, so that at the
1213 -- top level, we have the proper type. This "undoing" is a point at
1214 -- which a final overflow check may be applied.
1216 -- If the result type was not fiddled we are all set. We go to base
1217 -- types here because things may have been rewritten to generate the
1218 -- base type of the operand types.
1220 if Base_Type (Etype (Op)) = Base_Type (Result_Type) then
1225 elsif Is_RTE (Etype (Op), RE_Bignum) then
1227 -- We need a sequence that looks like:
1229 -- Rnn : Result_Type;
1232 -- M : Mark_Id := SS_Mark;
1234 -- Rnn := Long_Long_Integer'Base (From_Bignum (Op));
1238 -- This block is inserted (using Insert_Actions), and then the node
1239 -- is replaced with a reference to Rnn.
1241 -- A special case arises if our parent is a conversion node. In this
1242 -- case no point in generating a conversion to Result_Type, we will
1243 -- let the parent handle this. Note that this special case is not
1244 -- just about optimization. Consider
1248 -- X := Long_Long_Integer'Base (A * (B ** C));
1250 -- Now the product may fit in Long_Long_Integer but not in Integer.
1251 -- In MINIMIZED/ELIMINATED mode, we don't want to introduce an
1252 -- overflow exception for this intermediate value.
1255 Blk : constant Node_Id := Make_Bignum_Block (Loc);
1256 Rnn : constant Entity_Id := Make_Temporary (Loc, 'R', Op);
1262 RHS := Convert_From_Bignum (Op);
1264 if Nkind (P) /= N_Type_Conversion then
1265 Convert_To_And_Rewrite (Result_Type, RHS);
1266 Rtype := Result_Type;
1268 -- Interesting question, do we need a check on that conversion
1269 -- operation. Answer, not if we know the result is in range.
1270 -- At the moment we are not taking advantage of this. To be
1271 -- looked at later ???
1278 (First (Statements (Handled_Statement_Sequence (Blk))),
1279 Make_Assignment_Statement (Loc,
1280 Name => New_Occurrence_Of (Rnn, Loc),
1281 Expression => RHS));
1283 Insert_Actions (Op, New_List (
1284 Make_Object_Declaration (Loc,
1285 Defining_Identifier => Rnn,
1286 Object_Definition => New_Occurrence_Of (Rtype, Loc)),
1289 Rewrite (Op, New_Occurrence_Of (Rnn, Loc));
1290 Analyze_And_Resolve (Op);
1293 -- Here we know the result is Long_Long_Integer'Base, of that it has
1294 -- been rewritten because the parent operation is a conversion. See
1295 -- Apply_Arithmetic_Overflow_Strict.Conversion_Optimization.
1299 (Etype (Op) = LLIB or else Nkind (Parent (Op)) = N_Type_Conversion);
1301 -- All we need to do here is to convert the result to the proper
1302 -- result type. As explained above for the Bignum case, we can
1303 -- omit this if our parent is a type conversion.
1305 if Nkind (P) /= N_Type_Conversion then
1306 Convert_To_And_Rewrite (Result_Type, Op);
1309 Analyze_And_Resolve (Op);
1311 end Apply_Arithmetic_Overflow_Minimized_Eliminated;
1313 ----------------------------
1314 -- Apply_Constraint_Check --
1315 ----------------------------
1317 procedure Apply_Constraint_Check
1320 No_Sliding : Boolean := False)
1322 Desig_Typ : Entity_Id;
1325 -- No checks inside a generic (check the instantiations)
1327 if Inside_A_Generic then
1331 -- Apply required constraint checks
1333 if Is_Scalar_Type (Typ) then
1334 Apply_Scalar_Range_Check (N, Typ);
1336 elsif Is_Array_Type (Typ) then
1338 -- A useful optimization: an aggregate with only an others clause
1339 -- always has the right bounds.
1341 if Nkind (N) = N_Aggregate
1342 and then No (Expressions (N))
1344 (First (Choices (First (Component_Associations (N)))))
1350 if Is_Constrained (Typ) then
1351 Apply_Length_Check (N, Typ);
1354 Apply_Range_Check (N, Typ);
1357 Apply_Range_Check (N, Typ);
1360 elsif (Is_Record_Type (Typ) or else Is_Private_Type (Typ))
1361 and then Has_Discriminants (Base_Type (Typ))
1362 and then Is_Constrained (Typ)
1364 Apply_Discriminant_Check (N, Typ);
1366 elsif Is_Access_Type (Typ) then
1368 Desig_Typ := Designated_Type (Typ);
1370 -- No checks necessary if expression statically null
1372 if Known_Null (N) then
1373 if Can_Never_Be_Null (Typ) then
1374 Install_Null_Excluding_Check (N);
1377 -- No sliding possible on access to arrays
1379 elsif Is_Array_Type (Desig_Typ) then
1380 if Is_Constrained (Desig_Typ) then
1381 Apply_Length_Check (N, Typ);
1384 Apply_Range_Check (N, Typ);
1386 elsif Has_Discriminants (Base_Type (Desig_Typ))
1387 and then Is_Constrained (Desig_Typ)
1389 Apply_Discriminant_Check (N, Typ);
1392 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1393 -- this check if the constraint node is illegal, as shown by having
1394 -- an error posted. This additional guard prevents cascaded errors
1395 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1397 if Can_Never_Be_Null (Typ)
1398 and then not Can_Never_Be_Null (Etype (N))
1399 and then not Error_Posted (N)
1401 Install_Null_Excluding_Check (N);
1404 end Apply_Constraint_Check;
1406 ------------------------------
1407 -- Apply_Discriminant_Check --
1408 ------------------------------
1410 procedure Apply_Discriminant_Check
1413 Lhs : Node_Id := Empty)
1415 Loc : constant Source_Ptr := Sloc (N);
1416 Do_Access : constant Boolean := Is_Access_Type (Typ);
1417 S_Typ : Entity_Id := Etype (N);
1421 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean;
1422 -- A heap object with an indefinite subtype is constrained by its
1423 -- initial value, and assigning to it requires a constraint_check.
1424 -- The target may be an explicit dereference, or a renaming of one.
1426 function Is_Aliased_Unconstrained_Component return Boolean;
1427 -- It is possible for an aliased component to have a nominal
1428 -- unconstrained subtype (through instantiation). If this is a
1429 -- discriminated component assigned in the expansion of an aggregate
1430 -- in an initialization, the check must be suppressed. This unusual
1431 -- situation requires a predicate of its own.
1433 ----------------------------------
1434 -- Denotes_Explicit_Dereference --
1435 ----------------------------------
1437 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean is
1440 Nkind (Obj) = N_Explicit_Dereference
1442 (Is_Entity_Name (Obj)
1443 and then Present (Renamed_Object (Entity (Obj)))
1444 and then Nkind (Renamed_Object (Entity (Obj))) =
1445 N_Explicit_Dereference);
1446 end Denotes_Explicit_Dereference;
1448 ----------------------------------------
1449 -- Is_Aliased_Unconstrained_Component --
1450 ----------------------------------------
1452 function Is_Aliased_Unconstrained_Component return Boolean is
1457 if Nkind (Lhs) /= N_Selected_Component then
1460 Comp := Entity (Selector_Name (Lhs));
1461 Pref := Prefix (Lhs);
1464 if Ekind (Comp) /= E_Component
1465 or else not Is_Aliased (Comp)
1470 return not Comes_From_Source (Pref)
1471 and then In_Instance
1472 and then not Is_Constrained (Etype (Comp));
1473 end Is_Aliased_Unconstrained_Component;
1475 -- Start of processing for Apply_Discriminant_Check
1479 T_Typ := Designated_Type (Typ);
1484 -- Nothing to do if discriminant checks are suppressed or else no code
1485 -- is to be generated
1487 if not Expander_Active
1488 or else Discriminant_Checks_Suppressed (T_Typ)
1493 -- No discriminant checks necessary for an access when expression is
1494 -- statically Null. This is not only an optimization, it is fundamental
1495 -- because otherwise discriminant checks may be generated in init procs
1496 -- for types containing an access to a not-yet-frozen record, causing a
1497 -- deadly forward reference.
1499 -- Also, if the expression is of an access type whose designated type is
1500 -- incomplete, then the access value must be null and we suppress the
1503 if Known_Null (N) then
1506 elsif Is_Access_Type (S_Typ) then
1507 S_Typ := Designated_Type (S_Typ);
1509 if Ekind (S_Typ) = E_Incomplete_Type then
1514 -- If an assignment target is present, then we need to generate the
1515 -- actual subtype if the target is a parameter or aliased object with
1516 -- an unconstrained nominal subtype.
1518 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1519 -- subtype to the parameter and dereference cases, since other aliased
1520 -- objects are unconstrained (unless the nominal subtype is explicitly
1524 and then (Present (Param_Entity (Lhs))
1525 or else (Ada_Version < Ada_2005
1526 and then not Is_Constrained (T_Typ)
1527 and then Is_Aliased_View (Lhs)
1528 and then not Is_Aliased_Unconstrained_Component)
1529 or else (Ada_Version >= Ada_2005
1530 and then not Is_Constrained (T_Typ)
1531 and then Denotes_Explicit_Dereference (Lhs)
1532 and then Nkind (Original_Node (Lhs)) /=
1535 T_Typ := Get_Actual_Subtype (Lhs);
1538 -- Nothing to do if the type is unconstrained (this is the case where
1539 -- the actual subtype in the RM sense of N is unconstrained and no check
1542 if not Is_Constrained (T_Typ) then
1545 -- Ada 2005: nothing to do if the type is one for which there is a
1546 -- partial view that is constrained.
1548 elsif Ada_Version >= Ada_2005
1549 and then Object_Type_Has_Constrained_Partial_View
1550 (Typ => Base_Type (T_Typ),
1551 Scop => Current_Scope)
1556 -- Nothing to do if the type is an Unchecked_Union
1558 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1562 -- Suppress checks if the subtypes are the same. The check must be
1563 -- preserved in an assignment to a formal, because the constraint is
1564 -- given by the actual.
1566 if Nkind (Original_Node (N)) /= N_Allocator
1568 or else not Is_Entity_Name (Lhs)
1569 or else No (Param_Entity (Lhs)))
1572 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1573 and then not Is_Aliased_View (Lhs)
1578 -- We can also eliminate checks on allocators with a subtype mark that
1579 -- coincides with the context type. The context type may be a subtype
1580 -- without a constraint (common case, a generic actual).
1582 elsif Nkind (Original_Node (N)) = N_Allocator
1583 and then Is_Entity_Name (Expression (Original_Node (N)))
1586 Alloc_Typ : constant Entity_Id :=
1587 Entity (Expression (Original_Node (N)));
1590 if Alloc_Typ = T_Typ
1591 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1592 and then Is_Entity_Name (
1593 Subtype_Indication (Parent (T_Typ)))
1594 and then Alloc_Typ = Base_Type (T_Typ))
1602 -- See if we have a case where the types are both constrained, and all
1603 -- the constraints are constants. In this case, we can do the check
1604 -- successfully at compile time.
1606 -- We skip this check for the case where the node is rewritten as
1607 -- an allocator, because it already carries the context subtype,
1608 -- and extracting the discriminants from the aggregate is messy.
1610 if Is_Constrained (S_Typ)
1611 and then Nkind (Original_Node (N)) /= N_Allocator
1621 -- S_Typ may not have discriminants in the case where it is a
1622 -- private type completed by a default discriminated type. In that
1623 -- case, we need to get the constraints from the underlying type.
1624 -- If the underlying type is unconstrained (i.e. has no default
1625 -- discriminants) no check is needed.
1627 if Has_Discriminants (S_Typ) then
1628 Discr := First_Discriminant (S_Typ);
1629 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1632 Discr := First_Discriminant (Underlying_Type (S_Typ));
1635 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1641 -- A further optimization: if T_Typ is derived from S_Typ
1642 -- without imposing a constraint, no check is needed.
1644 if Nkind (Original_Node (Parent (T_Typ))) =
1645 N_Full_Type_Declaration
1648 Type_Def : constant Node_Id :=
1649 Type_Definition (Original_Node (Parent (T_Typ)));
1651 if Nkind (Type_Def) = N_Derived_Type_Definition
1652 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1653 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1661 -- Constraint may appear in full view of type
1663 if Ekind (T_Typ) = E_Private_Subtype
1664 and then Present (Full_View (T_Typ))
1667 First_Elmt (Discriminant_Constraint (Full_View (T_Typ)));
1670 First_Elmt (Discriminant_Constraint (T_Typ));
1673 while Present (Discr) loop
1674 ItemS := Node (DconS);
1675 ItemT := Node (DconT);
1677 -- For a discriminated component type constrained by the
1678 -- current instance of an enclosing type, there is no
1679 -- applicable discriminant check.
1681 if Nkind (ItemT) = N_Attribute_Reference
1682 and then Is_Access_Type (Etype (ItemT))
1683 and then Is_Entity_Name (Prefix (ItemT))
1684 and then Is_Type (Entity (Prefix (ItemT)))
1689 -- If the expressions for the discriminants are identical
1690 -- and it is side-effect free (for now just an entity),
1691 -- this may be a shared constraint, e.g. from a subtype
1692 -- without a constraint introduced as a generic actual.
1693 -- Examine other discriminants if any.
1696 and then Is_Entity_Name (ItemS)
1700 elsif not Is_OK_Static_Expression (ItemS)
1701 or else not Is_OK_Static_Expression (ItemT)
1705 elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
1706 if Do_Access then -- needs run-time check.
1709 Apply_Compile_Time_Constraint_Error
1710 (N, "incorrect value for discriminant&??",
1711 CE_Discriminant_Check_Failed, Ent => Discr);
1718 Next_Discriminant (Discr);
1727 -- Here we need a discriminant check. First build the expression
1728 -- for the comparisons of the discriminants:
1730 -- (n.disc1 /= typ.disc1) or else
1731 -- (n.disc2 /= typ.disc2) or else
1733 -- (n.discn /= typ.discn)
1735 Cond := Build_Discriminant_Checks (N, T_Typ);
1737 -- If Lhs is set and is a parameter, then the condition is guarded by:
1738 -- lhs'constrained and then (condition built above)
1740 if Present (Param_Entity (Lhs)) then
1744 Make_Attribute_Reference (Loc,
1745 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1746 Attribute_Name => Name_Constrained),
1747 Right_Opnd => Cond);
1751 Cond := Guard_Access (Cond, Loc, N);
1755 Make_Raise_Constraint_Error (Loc,
1757 Reason => CE_Discriminant_Check_Failed));
1758 end Apply_Discriminant_Check;
1760 -------------------------
1761 -- Apply_Divide_Checks --
1762 -------------------------
1764 procedure Apply_Divide_Checks (N : Node_Id) is
1765 Loc : constant Source_Ptr := Sloc (N);
1766 Typ : constant Entity_Id := Etype (N);
1767 Left : constant Node_Id := Left_Opnd (N);
1768 Right : constant Node_Id := Right_Opnd (N);
1770 Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
1771 -- Current overflow checking mode
1781 pragma Warnings (Off, Lhi);
1782 -- Don't actually use this value
1785 -- If we are operating in MINIMIZED or ELIMINATED mode, and we are
1786 -- operating on signed integer types, then the only thing this routine
1787 -- does is to call Apply_Arithmetic_Overflow_Minimized_Eliminated. That
1788 -- procedure will (possibly later on during recursive downward calls),
1789 -- ensure that any needed overflow/division checks are properly applied.
1791 if Mode in Minimized_Or_Eliminated
1792 and then Is_Signed_Integer_Type (Typ)
1794 Apply_Arithmetic_Overflow_Minimized_Eliminated (N);
1798 -- Proceed here in SUPPRESSED or CHECKED modes
1801 and then not Backend_Divide_Checks_On_Target
1802 and then Check_Needed (Right, Division_Check)
1804 Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True);
1806 -- Deal with division check
1808 if Do_Division_Check (N)
1809 and then not Division_Checks_Suppressed (Typ)
1811 Apply_Division_Check (N, Rlo, Rhi, ROK);
1814 -- Deal with overflow check
1816 if Do_Overflow_Check (N)
1817 and then not Overflow_Checks_Suppressed (Etype (N))
1819 Set_Do_Overflow_Check (N, False);
1821 -- Test for extremely annoying case of xxx'First divided by -1
1822 -- for division of signed integer types (only overflow case).
1824 if Nkind (N) = N_Op_Divide
1825 and then Is_Signed_Integer_Type (Typ)
1827 Determine_Range (Left, LOK, Llo, Lhi, Assume_Valid => True);
1828 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1830 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1832 ((not LOK) or else (Llo = LLB))
1835 Make_Raise_Constraint_Error (Loc,
1841 Duplicate_Subexpr_Move_Checks (Left),
1842 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1846 Left_Opnd => Duplicate_Subexpr (Right),
1847 Right_Opnd => Make_Integer_Literal (Loc, -1))),
1849 Reason => CE_Overflow_Check_Failed));
1854 end Apply_Divide_Checks;
1856 --------------------------
1857 -- Apply_Division_Check --
1858 --------------------------
1860 procedure Apply_Division_Check
1866 pragma Assert (Do_Division_Check (N));
1868 Loc : constant Source_Ptr := Sloc (N);
1869 Right : constant Node_Id := Right_Opnd (N);
1873 and then not Backend_Divide_Checks_On_Target
1874 and then Check_Needed (Right, Division_Check)
1876 -- See if division by zero possible, and if so generate test. This
1877 -- part of the test is not controlled by the -gnato switch, since
1878 -- it is a Division_Check and not an Overflow_Check.
1880 if Do_Division_Check (N) then
1881 Set_Do_Division_Check (N, False);
1883 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1885 Make_Raise_Constraint_Error (Loc,
1888 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1889 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1890 Reason => CE_Divide_By_Zero));
1894 end Apply_Division_Check;
1896 ----------------------------------
1897 -- Apply_Float_Conversion_Check --
1898 ----------------------------------
1900 -- Let F and I be the source and target types of the conversion. The RM
1901 -- specifies that a floating-point value X is rounded to the nearest
1902 -- integer, with halfway cases being rounded away from zero. The rounded
1903 -- value of X is checked against I'Range.
1905 -- The catch in the above paragraph is that there is no good way to know
1906 -- whether the round-to-integer operation resulted in overflow. A remedy is
1907 -- to perform a range check in the floating-point domain instead, however:
1909 -- (1) The bounds may not be known at compile time
1910 -- (2) The check must take into account rounding or truncation.
1911 -- (3) The range of type I may not be exactly representable in F.
1912 -- (4) For the rounding case, The end-points I'First - 0.5 and
1913 -- I'Last + 0.5 may or may not be in range, depending on the
1914 -- sign of I'First and I'Last.
1915 -- (5) X may be a NaN, which will fail any comparison
1917 -- The following steps correctly convert X with rounding:
1919 -- (1) If either I'First or I'Last is not known at compile time, use
1920 -- I'Base instead of I in the next three steps and perform a
1921 -- regular range check against I'Range after conversion.
1922 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1923 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1924 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1925 -- In other words, take one of the closest floating-point numbers
1926 -- (which is an integer value) to I'First, and see if it is in
1928 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1929 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1930 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1931 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1932 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1934 -- For the truncating case, replace steps (2) and (3) as follows:
1935 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1936 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1938 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1939 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1942 procedure Apply_Float_Conversion_Check
1944 Target_Typ : Entity_Id)
1946 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1947 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1948 Loc : constant Source_Ptr := Sloc (Ck_Node);
1949 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1950 Target_Base : constant Entity_Id :=
1951 Implementation_Base_Type (Target_Typ);
1953 Par : constant Node_Id := Parent (Ck_Node);
1954 pragma Assert (Nkind (Par) = N_Type_Conversion);
1955 -- Parent of check node, must be a type conversion
1957 Truncate : constant Boolean := Float_Truncate (Par);
1958 Max_Bound : constant Uint :=
1960 (Machine_Radix_Value (Expr_Type),
1961 Machine_Mantissa_Value (Expr_Type) - 1) - 1;
1963 -- Largest bound, so bound plus or minus half is a machine number of F
1965 Ifirst, Ilast : Uint;
1966 -- Bounds of integer type
1969 -- Bounds to check in floating-point domain
1971 Lo_OK, Hi_OK : Boolean;
1972 -- True iff Lo resp. Hi belongs to I'Range
1974 Lo_Chk, Hi_Chk : Node_Id;
1975 -- Expressions that are False iff check fails
1977 Reason : RT_Exception_Code;
1980 -- We do not need checks if we are not generating code (i.e. the full
1981 -- expander is not active). In SPARK mode, we specifically don't want
1982 -- the frontend to expand these checks, which are dealt with directly
1983 -- in the formal verification backend.
1985 if not Expander_Active then
1989 if not Compile_Time_Known_Value (LB)
1990 or not Compile_Time_Known_Value (HB)
1993 -- First check that the value falls in the range of the base type,
1994 -- to prevent overflow during conversion and then perform a
1995 -- regular range check against the (dynamic) bounds.
1997 pragma Assert (Target_Base /= Target_Typ);
1999 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Par);
2002 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
2003 Set_Etype (Temp, Target_Base);
2005 Insert_Action (Parent (Par),
2006 Make_Object_Declaration (Loc,
2007 Defining_Identifier => Temp,
2008 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
2009 Expression => New_Copy_Tree (Par)),
2010 Suppress => All_Checks);
2013 Make_Raise_Constraint_Error (Loc,
2016 Left_Opnd => New_Occurrence_Of (Temp, Loc),
2017 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
2018 Reason => CE_Range_Check_Failed));
2019 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
2025 -- Get the (static) bounds of the target type
2027 Ifirst := Expr_Value (LB);
2028 Ilast := Expr_Value (HB);
2030 -- A simple optimization: if the expression is a universal literal,
2031 -- we can do the comparison with the bounds and the conversion to
2032 -- an integer type statically. The range checks are unchanged.
2034 if Nkind (Ck_Node) = N_Real_Literal
2035 and then Etype (Ck_Node) = Universal_Real
2036 and then Is_Integer_Type (Target_Typ)
2037 and then Nkind (Parent (Ck_Node)) = N_Type_Conversion
2040 Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node));
2043 if Int_Val <= Ilast and then Int_Val >= Ifirst then
2045 -- Conversion is safe
2047 Rewrite (Parent (Ck_Node),
2048 Make_Integer_Literal (Loc, UI_To_Int (Int_Val)));
2049 Analyze_And_Resolve (Parent (Ck_Node), Target_Typ);
2055 -- Check against lower bound
2057 if Truncate and then Ifirst > 0 then
2058 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
2062 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
2065 elsif abs (Ifirst) < Max_Bound then
2066 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
2067 Lo_OK := (Ifirst > 0);
2070 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
2071 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
2076 -- Lo_Chk := (X >= Lo)
2078 Lo_Chk := Make_Op_Ge (Loc,
2079 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2080 Right_Opnd => Make_Real_Literal (Loc, Lo));
2083 -- Lo_Chk := (X > Lo)
2085 Lo_Chk := Make_Op_Gt (Loc,
2086 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2087 Right_Opnd => Make_Real_Literal (Loc, Lo));
2090 -- Check against higher bound
2092 if Truncate and then Ilast < 0 then
2093 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
2097 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
2100 elsif abs (Ilast) < Max_Bound then
2101 Hi := UR_From_Uint (Ilast) + Ureal_Half;
2102 Hi_OK := (Ilast < 0);
2104 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
2105 Hi_OK := (Hi <= UR_From_Uint (Ilast));
2110 -- Hi_Chk := (X <= Hi)
2112 Hi_Chk := Make_Op_Le (Loc,
2113 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2114 Right_Opnd => Make_Real_Literal (Loc, Hi));
2117 -- Hi_Chk := (X < Hi)
2119 Hi_Chk := Make_Op_Lt (Loc,
2120 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2121 Right_Opnd => Make_Real_Literal (Loc, Hi));
2124 -- If the bounds of the target type are the same as those of the base
2125 -- type, the check is an overflow check as a range check is not
2126 -- performed in these cases.
2128 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
2129 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
2131 Reason := CE_Overflow_Check_Failed;
2133 Reason := CE_Range_Check_Failed;
2136 -- Raise CE if either conditions does not hold
2138 Insert_Action (Ck_Node,
2139 Make_Raise_Constraint_Error (Loc,
2140 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
2142 end Apply_Float_Conversion_Check;
2144 ------------------------
2145 -- Apply_Length_Check --
2146 ------------------------
2148 procedure Apply_Length_Check
2150 Target_Typ : Entity_Id;
2151 Source_Typ : Entity_Id := Empty)
2154 Apply_Selected_Length_Checks
2155 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
2156 end Apply_Length_Check;
2158 -------------------------------------
2159 -- Apply_Parameter_Aliasing_Checks --
2160 -------------------------------------
2162 procedure Apply_Parameter_Aliasing_Checks
2166 Loc : constant Source_Ptr := Sloc (Call);
2168 function May_Cause_Aliasing
2169 (Formal_1 : Entity_Id;
2170 Formal_2 : Entity_Id) return Boolean;
2171 -- Determine whether two formal parameters can alias each other
2172 -- depending on their modes.
2174 function Original_Actual (N : Node_Id) return Node_Id;
2175 -- The expander may replace an actual with a temporary for the sake of
2176 -- side effect removal. The temporary may hide a potential aliasing as
2177 -- it does not share the address of the actual. This routine attempts
2178 -- to retrieve the original actual.
2180 procedure Overlap_Check
2181 (Actual_1 : Node_Id;
2183 Formal_1 : Entity_Id;
2184 Formal_2 : Entity_Id;
2185 Check : in out Node_Id);
2186 -- Create a check to determine whether Actual_1 overlaps with Actual_2.
2187 -- If detailed exception messages are enabled, the check is augmented to
2188 -- provide information about the names of the corresponding formals. See
2189 -- the body for details. Actual_1 and Actual_2 denote the two actuals to
2190 -- be tested. Formal_1 and Formal_2 denote the corresponding formals.
2191 -- Check contains all and-ed simple tests generated so far or remains
2192 -- unchanged in the case of detailed exception messaged.
2194 ------------------------
2195 -- May_Cause_Aliasing --
2196 ------------------------
2198 function May_Cause_Aliasing
2199 (Formal_1 : Entity_Id;
2200 Formal_2 : Entity_Id) return Boolean
2203 -- The following combination cannot lead to aliasing
2205 -- Formal 1 Formal 2
2208 if Ekind (Formal_1) = E_In_Parameter
2210 Ekind (Formal_2) = E_In_Parameter
2214 -- The following combinations may lead to aliasing
2216 -- Formal 1 Formal 2
2226 end May_Cause_Aliasing;
2228 ---------------------
2229 -- Original_Actual --
2230 ---------------------
2232 function Original_Actual (N : Node_Id) return Node_Id is
2234 if Nkind (N) = N_Type_Conversion then
2235 return Expression (N);
2237 -- The expander created a temporary to capture the result of a type
2238 -- conversion where the expression is the real actual.
2240 elsif Nkind (N) = N_Identifier
2241 and then Present (Original_Node (N))
2242 and then Nkind (Original_Node (N)) = N_Type_Conversion
2244 return Expression (Original_Node (N));
2248 end Original_Actual;
2254 procedure Overlap_Check
2255 (Actual_1 : Node_Id;
2257 Formal_1 : Entity_Id;
2258 Formal_2 : Entity_Id;
2259 Check : in out Node_Id)
2262 ID_Casing : constant Casing_Type :=
2263 Identifier_Casing (Source_Index (Current_Sem_Unit));
2267 -- Actual_1'Overlaps_Storage (Actual_2)
2270 Make_Attribute_Reference (Loc,
2271 Prefix => New_Copy_Tree (Original_Actual (Actual_1)),
2272 Attribute_Name => Name_Overlaps_Storage,
2274 New_List (New_Copy_Tree (Original_Actual (Actual_2))));
2276 -- Generate the following check when detailed exception messages are
2279 -- if Actual_1'Overlaps_Storage (Actual_2) then
2280 -- raise Program_Error with <detailed message>;
2283 if Exception_Extra_Info then
2286 -- Do not generate location information for internal calls
2288 if Comes_From_Source (Call) then
2289 Store_String_Chars (Build_Location_String (Loc));
2290 Store_String_Char (' ');
2293 Store_String_Chars ("aliased parameters, actuals for """);
2295 Get_Name_String (Chars (Formal_1));
2296 Set_Casing (ID_Casing);
2297 Store_String_Chars (Name_Buffer (1 .. Name_Len));
2299 Store_String_Chars (""" and """);
2301 Get_Name_String (Chars (Formal_2));
2302 Set_Casing (ID_Casing);
2303 Store_String_Chars (Name_Buffer (1 .. Name_Len));
2305 Store_String_Chars (""" overlap");
2307 Insert_Action (Call,
2308 Make_If_Statement (Loc,
2310 Then_Statements => New_List (
2311 Make_Raise_Statement (Loc,
2313 New_Occurrence_Of (Standard_Program_Error, Loc),
2314 Expression => Make_String_Literal (Loc, End_String)))));
2316 -- Create a sequence of overlapping checks by and-ing them all
2326 Right_Opnd => Cond);
2336 Formal_1 : Entity_Id;
2337 Formal_2 : Entity_Id;
2339 -- Start of processing for Apply_Parameter_Aliasing_Checks
2344 Actual_1 := First_Actual (Call);
2345 Formal_1 := First_Formal (Subp);
2346 while Present (Actual_1) and then Present (Formal_1) loop
2348 -- Ensure that the actual is an object that is not passed by value.
2349 -- Elementary types are always passed by value, therefore actuals of
2350 -- such types cannot lead to aliasing.
2352 if Is_Object_Reference (Original_Actual (Actual_1))
2353 and then not Is_Elementary_Type (Etype (Original_Actual (Actual_1)))
2355 Actual_2 := Next_Actual (Actual_1);
2356 Formal_2 := Next_Formal (Formal_1);
2357 while Present (Actual_2) and then Present (Formal_2) loop
2359 -- The other actual we are testing against must also denote
2360 -- a non pass-by-value object. Generate the check only when
2361 -- the mode of the two formals may lead to aliasing.
2363 if Is_Object_Reference (Original_Actual (Actual_2))
2365 Is_Elementary_Type (Etype (Original_Actual (Actual_2)))
2366 and then May_Cause_Aliasing (Formal_1, Formal_2)
2369 (Actual_1 => Actual_1,
2370 Actual_2 => Actual_2,
2371 Formal_1 => Formal_1,
2372 Formal_2 => Formal_2,
2376 Next_Actual (Actual_2);
2377 Next_Formal (Formal_2);
2381 Next_Actual (Actual_1);
2382 Next_Formal (Formal_1);
2385 -- Place a simple check right before the call
2387 if Present (Check) and then not Exception_Extra_Info then
2388 Insert_Action (Call,
2389 Make_Raise_Program_Error (Loc,
2391 Reason => PE_Aliased_Parameters));
2393 end Apply_Parameter_Aliasing_Checks;
2395 -------------------------------------
2396 -- Apply_Parameter_Validity_Checks --
2397 -------------------------------------
2399 procedure Apply_Parameter_Validity_Checks (Subp : Entity_Id) is
2400 Subp_Decl : Node_Id;
2402 procedure Add_Validity_Check
2403 (Context : Entity_Id;
2405 For_Result : Boolean := False);
2406 -- Add a single 'Valid[_Scalar] check which verifies the initialization
2407 -- of Context. PPC_Nam denotes the pre or post condition pragma name.
2408 -- Set flag For_Result when to verify the result of a function.
2410 procedure Build_PPC_Pragma (PPC_Nam : Name_Id; Check : Node_Id);
2411 -- Create a pre or post condition pragma with name PPC_Nam which
2412 -- tests expression Check.
2414 ------------------------
2415 -- Add_Validity_Check --
2416 ------------------------
2418 procedure Add_Validity_Check
2419 (Context : Entity_Id;
2421 For_Result : Boolean := False)
2423 Loc : constant Source_Ptr := Sloc (Subp);
2424 Typ : constant Entity_Id := Etype (Context);
2429 -- For scalars, generate 'Valid test
2431 if Is_Scalar_Type (Typ) then
2434 -- For any non-scalar with scalar parts, generate 'Valid_Scalars test
2436 elsif Scalar_Part_Present (Typ) then
2437 Nam := Name_Valid_Scalars;
2439 -- No test needed for other cases (no scalars to test)
2445 -- Step 1: Create the expression to verify the validity of the
2448 Check := New_Occurrence_Of (Context, Loc);
2450 -- When processing a function result, use 'Result. Generate
2455 Make_Attribute_Reference (Loc,
2457 Attribute_Name => Name_Result);
2461 -- Context['Result]'Valid[_Scalars]
2464 Make_Attribute_Reference (Loc,
2466 Attribute_Name => Nam);
2468 -- Step 2: Create a pre or post condition pragma
2470 Build_PPC_Pragma (PPC_Nam, Check);
2471 end Add_Validity_Check;
2473 ----------------------
2474 -- Build_PPC_Pragma --
2475 ----------------------
2477 procedure Build_PPC_Pragma (PPC_Nam : Name_Id; Check : Node_Id) is
2478 Loc : constant Source_Ptr := Sloc (Subp);
2485 Pragma_Identifier => Make_Identifier (Loc, PPC_Nam),
2486 Pragma_Argument_Associations => New_List (
2487 Make_Pragma_Argument_Association (Loc,
2488 Chars => Name_Check,
2489 Expression => Check)));
2491 -- Add a message unless exception messages are suppressed
2493 if not Exception_Locations_Suppressed then
2494 Append_To (Pragma_Argument_Associations (Prag),
2495 Make_Pragma_Argument_Association (Loc,
2496 Chars => Name_Message,
2498 Make_String_Literal (Loc,
2499 Strval => "failed " & Get_Name_String (PPC_Nam) &
2500 " from " & Build_Location_String (Loc))));
2503 -- Insert the pragma in the tree
2505 if Nkind (Parent (Subp_Decl)) = N_Compilation_Unit then
2506 Add_Global_Declaration (Prag);
2509 -- PPC pragmas associated with subprogram bodies must be inserted in
2510 -- the declarative part of the body.
2512 elsif Nkind (Subp_Decl) = N_Subprogram_Body then
2513 Decls := Declarations (Subp_Decl);
2517 Set_Declarations (Subp_Decl, Decls);
2520 Prepend_To (Decls, Prag);
2522 -- Ensure the proper visibility of the subprogram body and its
2529 -- For subprogram declarations insert the PPC pragma right after the
2530 -- declarative node.
2533 Insert_After_And_Analyze (Subp_Decl, Prag);
2535 end Build_PPC_Pragma;
2540 Subp_Spec : Node_Id;
2542 -- Start of processing for Apply_Parameter_Validity_Checks
2545 -- Extract the subprogram specification and declaration nodes
2547 Subp_Spec := Parent (Subp);
2549 if Nkind (Subp_Spec) = N_Defining_Program_Unit_Name then
2550 Subp_Spec := Parent (Subp_Spec);
2553 Subp_Decl := Parent (Subp_Spec);
2555 if not Comes_From_Source (Subp)
2557 -- Do not process formal subprograms because the corresponding actual
2558 -- will receive the proper checks when the instance is analyzed.
2560 or else Is_Formal_Subprogram (Subp)
2562 -- Do not process imported subprograms since pre and post conditions
2563 -- are never verified on routines coming from a different language.
2565 or else Is_Imported (Subp)
2566 or else Is_Intrinsic_Subprogram (Subp)
2568 -- The PPC pragmas generated by this routine do not correspond to
2569 -- source aspects, therefore they cannot be applied to abstract
2572 or else Nkind (Subp_Decl) = N_Abstract_Subprogram_Declaration
2574 -- Do not consider subprogram renaminds because the renamed entity
2575 -- already has the proper PPC pragmas.
2577 or else Nkind (Subp_Decl) = N_Subprogram_Renaming_Declaration
2579 -- Do not process null procedures because there is no benefit of
2580 -- adding the checks to a no action routine.
2582 or else (Nkind (Subp_Spec) = N_Procedure_Specification
2583 and then Null_Present (Subp_Spec))
2588 -- Inspect all the formals applying aliasing and scalar initialization
2589 -- checks where applicable.
2591 Formal := First_Formal (Subp);
2592 while Present (Formal) loop
2594 -- Generate the following scalar initialization checks for each
2595 -- formal parameter:
2597 -- mode IN - Pre => Formal'Valid[_Scalars]
2598 -- mode IN OUT - Pre, Post => Formal'Valid[_Scalars]
2599 -- mode OUT - Post => Formal'Valid[_Scalars]
2601 if Check_Validity_Of_Parameters then
2602 if Ekind_In (Formal, E_In_Parameter, E_In_Out_Parameter) then
2603 Add_Validity_Check (Formal, Name_Precondition, False);
2606 if Ekind_In (Formal, E_In_Out_Parameter, E_Out_Parameter) then
2607 Add_Validity_Check (Formal, Name_Postcondition, False);
2611 Next_Formal (Formal);
2614 -- Generate following scalar initialization check for function result:
2616 -- Post => Subp'Result'Valid[_Scalars]
2618 if Check_Validity_Of_Parameters and then Ekind (Subp) = E_Function then
2619 Add_Validity_Check (Subp, Name_Postcondition, True);
2621 end Apply_Parameter_Validity_Checks;
2623 ---------------------------
2624 -- Apply_Predicate_Check --
2625 ---------------------------
2627 procedure Apply_Predicate_Check (N : Node_Id; Typ : Entity_Id) is
2631 if Present (Predicate_Function (Typ)) then
2634 while Present (S) and then not Is_Subprogram (S) loop
2638 -- A predicate check does not apply within internally generated
2639 -- subprograms, such as TSS functions.
2641 if Within_Internal_Subprogram then
2644 -- If the check appears within the predicate function itself, it
2645 -- means that the user specified a check whose formal is the
2646 -- predicated subtype itself, rather than some covering type. This
2647 -- is likely to be a common error, and thus deserves a warning.
2649 elsif Present (S) and then S = Predicate_Function (Typ) then
2651 ("predicate check includes a function call that "
2652 & "requires a predicate check??", Parent (N));
2654 ("\this will result in infinite recursion??", Parent (N));
2656 Make_Raise_Storage_Error (Sloc (N),
2657 Reason => SE_Infinite_Recursion));
2659 -- Here for normal case of predicate active
2662 -- If the type has a static predicate and the expression is known
2663 -- at compile time, see if the expression satisfies the predicate.
2665 Check_Expression_Against_Static_Predicate (N, Typ);
2668 Make_Predicate_Check (Typ, Duplicate_Subexpr (N)));
2671 end Apply_Predicate_Check;
2673 -----------------------
2674 -- Apply_Range_Check --
2675 -----------------------
2677 procedure Apply_Range_Check
2679 Target_Typ : Entity_Id;
2680 Source_Typ : Entity_Id := Empty)
2683 Apply_Selected_Range_Checks
2684 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
2685 end Apply_Range_Check;
2687 ------------------------------
2688 -- Apply_Scalar_Range_Check --
2689 ------------------------------
2691 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
2692 -- off if it is already set on.
2694 procedure Apply_Scalar_Range_Check
2696 Target_Typ : Entity_Id;
2697 Source_Typ : Entity_Id := Empty;
2698 Fixed_Int : Boolean := False)
2700 Parnt : constant Node_Id := Parent (Expr);
2702 Arr : Node_Id := Empty; -- initialize to prevent warning
2703 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
2706 Is_Subscr_Ref : Boolean;
2707 -- Set true if Expr is a subscript
2709 Is_Unconstrained_Subscr_Ref : Boolean;
2710 -- Set true if Expr is a subscript of an unconstrained array. In this
2711 -- case we do not attempt to do an analysis of the value against the
2712 -- range of the subscript, since we don't know the actual subtype.
2715 -- Set to True if Expr should be regarded as a real value even though
2716 -- the type of Expr might be discrete.
2718 procedure Bad_Value;
2719 -- Procedure called if value is determined to be out of range
2725 procedure Bad_Value is
2727 Apply_Compile_Time_Constraint_Error
2728 (Expr, "value not in range of}??", CE_Range_Check_Failed,
2733 -- Start of processing for Apply_Scalar_Range_Check
2736 -- Return if check obviously not needed
2739 -- Not needed inside generic
2743 -- Not needed if previous error
2745 or else Target_Typ = Any_Type
2746 or else Nkind (Expr) = N_Error
2748 -- Not needed for non-scalar type
2750 or else not Is_Scalar_Type (Target_Typ)
2752 -- Not needed if we know node raises CE already
2754 or else Raises_Constraint_Error (Expr)
2759 -- Now, see if checks are suppressed
2762 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
2764 if Is_Subscr_Ref then
2765 Arr := Prefix (Parnt);
2766 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
2768 if Is_Access_Type (Arr_Typ) then
2769 Arr_Typ := Designated_Type (Arr_Typ);
2773 if not Do_Range_Check (Expr) then
2775 -- Subscript reference. Check for Index_Checks suppressed
2777 if Is_Subscr_Ref then
2779 -- Check array type and its base type
2781 if Index_Checks_Suppressed (Arr_Typ)
2782 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
2786 -- Check array itself if it is an entity name
2788 elsif Is_Entity_Name (Arr)
2789 and then Index_Checks_Suppressed (Entity (Arr))
2793 -- Check expression itself if it is an entity name
2795 elsif Is_Entity_Name (Expr)
2796 and then Index_Checks_Suppressed (Entity (Expr))
2801 -- All other cases, check for Range_Checks suppressed
2804 -- Check target type and its base type
2806 if Range_Checks_Suppressed (Target_Typ)
2807 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
2811 -- Check expression itself if it is an entity name
2813 elsif Is_Entity_Name (Expr)
2814 and then Range_Checks_Suppressed (Entity (Expr))
2818 -- If Expr is part of an assignment statement, then check left
2819 -- side of assignment if it is an entity name.
2821 elsif Nkind (Parnt) = N_Assignment_Statement
2822 and then Is_Entity_Name (Name (Parnt))
2823 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
2830 -- Do not set range checks if they are killed
2832 if Nkind (Expr) = N_Unchecked_Type_Conversion
2833 and then Kill_Range_Check (Expr)
2838 -- Do not set range checks for any values from System.Scalar_Values
2839 -- since the whole idea of such values is to avoid checking them.
2841 if Is_Entity_Name (Expr)
2842 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
2847 -- Now see if we need a check
2849 if No (Source_Typ) then
2850 S_Typ := Etype (Expr);
2852 S_Typ := Source_Typ;
2855 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
2859 Is_Unconstrained_Subscr_Ref :=
2860 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
2862 -- Special checks for floating-point type
2864 if Is_Floating_Point_Type (S_Typ) then
2866 -- Always do a range check if the source type includes infinities and
2867 -- the target type does not include infinities. We do not do this if
2868 -- range checks are killed.
2870 if Has_Infinities (S_Typ)
2871 and then not Has_Infinities (Target_Typ)
2873 Enable_Range_Check (Expr);
2875 -- Always do a range check for operators if option set
2877 elsif Check_Float_Overflow and then Nkind (Expr) in N_Op then
2878 Enable_Range_Check (Expr);
2882 -- Return if we know expression is definitely in the range of the target
2883 -- type as determined by Determine_Range. Right now we only do this for
2884 -- discrete types, and not fixed-point or floating-point types.
2886 -- The additional less-precise tests below catch these cases
2888 -- Note: skip this if we are given a source_typ, since the point of
2889 -- supplying a Source_Typ is to stop us looking at the expression.
2890 -- We could sharpen this test to be out parameters only ???
2892 if Is_Discrete_Type (Target_Typ)
2893 and then Is_Discrete_Type (Etype (Expr))
2894 and then not Is_Unconstrained_Subscr_Ref
2895 and then No (Source_Typ)
2898 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
2899 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
2904 if Compile_Time_Known_Value (Tlo)
2905 and then Compile_Time_Known_Value (Thi)
2908 Lov : constant Uint := Expr_Value (Tlo);
2909 Hiv : constant Uint := Expr_Value (Thi);
2912 -- If range is null, we for sure have a constraint error
2913 -- (we don't even need to look at the value involved,
2914 -- since all possible values will raise CE).
2921 -- Otherwise determine range of value
2923 Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True);
2927 -- If definitely in range, all OK
2929 if Lo >= Lov and then Hi <= Hiv then
2932 -- If definitely not in range, warn
2934 elsif Lov > Hi or else Hiv < Lo then
2938 -- Otherwise we don't know
2950 Is_Floating_Point_Type (S_Typ)
2951 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
2953 -- Check if we can determine at compile time whether Expr is in the
2954 -- range of the target type. Note that if S_Typ is within the bounds
2955 -- of Target_Typ then this must be the case. This check is meaningful
2956 -- only if this is not a conversion between integer and real types.
2958 if not Is_Unconstrained_Subscr_Ref
2959 and then Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
2961 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
2963 Is_In_Range (Expr, Target_Typ,
2964 Assume_Valid => True,
2965 Fixed_Int => Fixed_Int,
2966 Int_Real => Int_Real))
2970 elsif Is_Out_Of_Range (Expr, Target_Typ,
2971 Assume_Valid => True,
2972 Fixed_Int => Fixed_Int,
2973 Int_Real => Int_Real)
2978 -- Floating-point case
2979 -- In the floating-point case, we only do range checks if the type is
2980 -- constrained. We definitely do NOT want range checks for unconstrained
2981 -- types, since we want to have infinities
2983 elsif Is_Floating_Point_Type (S_Typ) then
2985 -- Normally, we only do range checks if the type is constrained. We do
2986 -- NOT want range checks for unconstrained types, since we want to have
2987 -- infinities. Override this decision in Check_Float_Overflow mode.
2989 if Is_Constrained (S_Typ) or else Check_Float_Overflow then
2990 Enable_Range_Check (Expr);
2993 -- For all other cases we enable a range check unconditionally
2996 Enable_Range_Check (Expr);
2999 end Apply_Scalar_Range_Check;
3001 ----------------------------------
3002 -- Apply_Selected_Length_Checks --
3003 ----------------------------------
3005 procedure Apply_Selected_Length_Checks
3007 Target_Typ : Entity_Id;
3008 Source_Typ : Entity_Id;
3009 Do_Static : Boolean)
3012 R_Result : Check_Result;
3015 Loc : constant Source_Ptr := Sloc (Ck_Node);
3016 Checks_On : constant Boolean :=
3017 (not Index_Checks_Suppressed (Target_Typ))
3018 or else (not Length_Checks_Suppressed (Target_Typ));
3021 -- Note: this means that we lose some useful warnings if the expander
3022 -- is not active, and we also lose these warnings in SPARK mode ???
3024 if not Expander_Active then
3029 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
3031 for J in 1 .. 2 loop
3032 R_Cno := R_Result (J);
3033 exit when No (R_Cno);
3035 -- A length check may mention an Itype which is attached to a
3036 -- subsequent node. At the top level in a package this can cause
3037 -- an order-of-elaboration problem, so we make sure that the itype
3038 -- is referenced now.
3040 if Ekind (Current_Scope) = E_Package
3041 and then Is_Compilation_Unit (Current_Scope)
3043 Ensure_Defined (Target_Typ, Ck_Node);
3045 if Present (Source_Typ) then
3046 Ensure_Defined (Source_Typ, Ck_Node);
3048 elsif Is_Itype (Etype (Ck_Node)) then
3049 Ensure_Defined (Etype (Ck_Node), Ck_Node);
3053 -- If the item is a conditional raise of constraint error, then have
3054 -- a look at what check is being performed and ???
3056 if Nkind (R_Cno) = N_Raise_Constraint_Error
3057 and then Present (Condition (R_Cno))
3059 Cond := Condition (R_Cno);
3061 -- Case where node does not now have a dynamic check
3063 if not Has_Dynamic_Length_Check (Ck_Node) then
3065 -- If checks are on, just insert the check
3068 Insert_Action (Ck_Node, R_Cno);
3070 if not Do_Static then
3071 Set_Has_Dynamic_Length_Check (Ck_Node);
3074 -- If checks are off, then analyze the length check after
3075 -- temporarily attaching it to the tree in case the relevant
3076 -- condition can be evaluated at compile time. We still want a
3077 -- compile time warning in this case.
3080 Set_Parent (R_Cno, Ck_Node);
3085 -- Output a warning if the condition is known to be True
3087 if Is_Entity_Name (Cond)
3088 and then Entity (Cond) = Standard_True
3090 Apply_Compile_Time_Constraint_Error
3091 (Ck_Node, "wrong length for array of}??",
3092 CE_Length_Check_Failed,
3096 -- If we were only doing a static check, or if checks are not
3097 -- on, then we want to delete the check, since it is not needed.
3098 -- We do this by replacing the if statement by a null statement
3100 elsif Do_Static or else not Checks_On then
3101 Remove_Warning_Messages (R_Cno);
3102 Rewrite (R_Cno, Make_Null_Statement (Loc));
3106 Install_Static_Check (R_Cno, Loc);
3109 end Apply_Selected_Length_Checks;
3111 ---------------------------------
3112 -- Apply_Selected_Range_Checks --
3113 ---------------------------------
3115 procedure Apply_Selected_Range_Checks
3117 Target_Typ : Entity_Id;
3118 Source_Typ : Entity_Id;
3119 Do_Static : Boolean)
3121 Loc : constant Source_Ptr := Sloc (Ck_Node);
3122 Checks_On : constant Boolean :=
3123 not Index_Checks_Suppressed (Target_Typ)
3125 not Range_Checks_Suppressed (Target_Typ);
3129 R_Result : Check_Result;
3132 if not Expander_Active or not Checks_On then
3137 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
3139 for J in 1 .. 2 loop
3140 R_Cno := R_Result (J);
3141 exit when No (R_Cno);
3143 -- The range check requires runtime evaluation. Depending on what its
3144 -- triggering condition is, the check may be converted into a compile
3145 -- time constraint check.
3147 if Nkind (R_Cno) = N_Raise_Constraint_Error
3148 and then Present (Condition (R_Cno))
3150 Cond := Condition (R_Cno);
3152 -- Insert the range check before the related context. Note that
3153 -- this action analyses the triggering condition.
3155 Insert_Action (Ck_Node, R_Cno);
3157 -- This old code doesn't make sense, why is the context flagged as
3158 -- requiring dynamic range checks now in the middle of generating
3161 if not Do_Static then
3162 Set_Has_Dynamic_Range_Check (Ck_Node);
3165 -- The triggering condition evaluates to True, the range check
3166 -- can be converted into a compile time constraint check.
3168 if Is_Entity_Name (Cond)
3169 and then Entity (Cond) = Standard_True
3171 -- Since an N_Range is technically not an expression, we have
3172 -- to set one of the bounds to C_E and then just flag the
3173 -- N_Range. The warning message will point to the lower bound
3174 -- and complain about a range, which seems OK.
3176 if Nkind (Ck_Node) = N_Range then
3177 Apply_Compile_Time_Constraint_Error
3178 (Low_Bound (Ck_Node),
3179 "static range out of bounds of}??",
3180 CE_Range_Check_Failed,
3184 Set_Raises_Constraint_Error (Ck_Node);
3187 Apply_Compile_Time_Constraint_Error
3189 "static value out of range of}??",
3190 CE_Range_Check_Failed,
3195 -- If we were only doing a static check, or if checks are not
3196 -- on, then we want to delete the check, since it is not needed.
3197 -- We do this by replacing the if statement by a null statement
3199 -- Why are we even generating checks if checks are turned off ???
3201 elsif Do_Static or else not Checks_On then
3202 Remove_Warning_Messages (R_Cno);
3203 Rewrite (R_Cno, Make_Null_Statement (Loc));
3206 -- The range check raises Constrant_Error explicitly
3209 Install_Static_Check (R_Cno, Loc);
3212 end Apply_Selected_Range_Checks;
3214 -------------------------------
3215 -- Apply_Static_Length_Check --
3216 -------------------------------
3218 procedure Apply_Static_Length_Check
3220 Target_Typ : Entity_Id;
3221 Source_Typ : Entity_Id := Empty)
3224 Apply_Selected_Length_Checks
3225 (Expr, Target_Typ, Source_Typ, Do_Static => True);
3226 end Apply_Static_Length_Check;
3228 -------------------------------------
3229 -- Apply_Subscript_Validity_Checks --
3230 -------------------------------------
3232 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
3236 pragma Assert (Nkind (Expr) = N_Indexed_Component);
3238 -- Loop through subscripts
3240 Sub := First (Expressions (Expr));
3241 while Present (Sub) loop
3243 -- Check one subscript. Note that we do not worry about enumeration
3244 -- type with holes, since we will convert the value to a Pos value
3245 -- for the subscript, and that convert will do the necessary validity
3248 Ensure_Valid (Sub, Holes_OK => True);
3250 -- Move to next subscript
3254 end Apply_Subscript_Validity_Checks;
3256 ----------------------------------
3257 -- Apply_Type_Conversion_Checks --
3258 ----------------------------------
3260 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
3261 Target_Type : constant Entity_Id := Etype (N);
3262 Target_Base : constant Entity_Id := Base_Type (Target_Type);
3263 Expr : constant Node_Id := Expression (N);
3265 Expr_Type : constant Entity_Id := Underlying_Type (Etype (Expr));
3266 -- Note: if Etype (Expr) is a private type without discriminants, its
3267 -- full view might have discriminants with defaults, so we need the
3268 -- full view here to retrieve the constraints.
3271 if Inside_A_Generic then
3274 -- Skip these checks if serious errors detected, there are some nasty
3275 -- situations of incomplete trees that blow things up.
3277 elsif Serious_Errors_Detected > 0 then
3280 -- Never generate discriminant checks for Unchecked_Union types
3282 elsif Present (Expr_Type)
3283 and then Is_Unchecked_Union (Expr_Type)
3287 -- Scalar type conversions of the form Target_Type (Expr) require a
3288 -- range check if we cannot be sure that Expr is in the base type of
3289 -- Target_Typ and also that Expr is in the range of Target_Typ. These
3290 -- are not quite the same condition from an implementation point of
3291 -- view, but clearly the second includes the first.
3293 elsif Is_Scalar_Type (Target_Type) then
3295 Conv_OK : constant Boolean := Conversion_OK (N);
3296 -- If the Conversion_OK flag on the type conversion is set and no
3297 -- floating-point type is involved in the type conversion then
3298 -- fixed-point values must be read as integral values.
3300 Float_To_Int : constant Boolean :=
3301 Is_Floating_Point_Type (Expr_Type)
3302 and then Is_Integer_Type (Target_Type);
3305 if not Overflow_Checks_Suppressed (Target_Base)
3306 and then not Overflow_Checks_Suppressed (Target_Type)
3308 In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK)
3309 and then not Float_To_Int
3311 Activate_Overflow_Check (N);
3314 if not Range_Checks_Suppressed (Target_Type)
3315 and then not Range_Checks_Suppressed (Expr_Type)
3317 if Float_To_Int then
3318 Apply_Float_Conversion_Check (Expr, Target_Type);
3320 Apply_Scalar_Range_Check
3321 (Expr, Target_Type, Fixed_Int => Conv_OK);
3323 -- If the target type has predicates, we need to indicate
3324 -- the need for a check, even if Determine_Range finds that
3325 -- the value is within bounds. This may be the case e.g for
3326 -- a division with a constant denominator.
3328 if Has_Predicates (Target_Type) then
3329 Enable_Range_Check (Expr);
3335 elsif Comes_From_Source (N)
3336 and then not Discriminant_Checks_Suppressed (Target_Type)
3337 and then Is_Record_Type (Target_Type)
3338 and then Is_Derived_Type (Target_Type)
3339 and then not Is_Tagged_Type (Target_Type)
3340 and then not Is_Constrained (Target_Type)
3341 and then Present (Stored_Constraint (Target_Type))
3343 -- An unconstrained derived type may have inherited discriminant.
3344 -- Build an actual discriminant constraint list using the stored
3345 -- constraint, to verify that the expression of the parent type
3346 -- satisfies the constraints imposed by the (unconstrained) derived
3347 -- type. This applies to value conversions, not to view conversions
3351 Loc : constant Source_Ptr := Sloc (N);
3353 Constraint : Elmt_Id;
3354 Discr_Value : Node_Id;
3357 New_Constraints : constant Elist_Id := New_Elmt_List;
3358 Old_Constraints : constant Elist_Id :=
3359 Discriminant_Constraint (Expr_Type);
3362 Constraint := First_Elmt (Stored_Constraint (Target_Type));
3363 while Present (Constraint) loop
3364 Discr_Value := Node (Constraint);
3366 if Is_Entity_Name (Discr_Value)
3367 and then Ekind (Entity (Discr_Value)) = E_Discriminant
3369 Discr := Corresponding_Discriminant (Entity (Discr_Value));
3372 and then Scope (Discr) = Base_Type (Expr_Type)
3374 -- Parent is constrained by new discriminant. Obtain
3375 -- Value of original discriminant in expression. If the
3376 -- new discriminant has been used to constrain more than
3377 -- one of the stored discriminants, this will provide the
3378 -- required consistency check.
3381 (Make_Selected_Component (Loc,
3383 Duplicate_Subexpr_No_Checks
3384 (Expr, Name_Req => True),
3386 Make_Identifier (Loc, Chars (Discr))),
3390 -- Discriminant of more remote ancestor ???
3395 -- Derived type definition has an explicit value for this
3396 -- stored discriminant.
3400 (Duplicate_Subexpr_No_Checks (Discr_Value),
3404 Next_Elmt (Constraint);
3407 -- Use the unconstrained expression type to retrieve the
3408 -- discriminants of the parent, and apply momentarily the
3409 -- discriminant constraint synthesized above.
3411 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
3412 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
3413 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
3416 Make_Raise_Constraint_Error (Loc,
3418 Reason => CE_Discriminant_Check_Failed));
3421 -- For arrays, checks are set now, but conversions are applied during
3422 -- expansion, to take into accounts changes of representation. The
3423 -- checks become range checks on the base type or length checks on the
3424 -- subtype, depending on whether the target type is unconstrained or
3425 -- constrained. Note that the range check is put on the expression of a
3426 -- type conversion, while the length check is put on the type conversion
3429 elsif Is_Array_Type (Target_Type) then
3430 if Is_Constrained (Target_Type) then
3431 Set_Do_Length_Check (N);
3433 Set_Do_Range_Check (Expr);
3436 end Apply_Type_Conversion_Checks;
3438 ----------------------------------------------
3439 -- Apply_Universal_Integer_Attribute_Checks --
3440 ----------------------------------------------
3442 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
3443 Loc : constant Source_Ptr := Sloc (N);
3444 Typ : constant Entity_Id := Etype (N);
3447 if Inside_A_Generic then
3450 -- Nothing to do if checks are suppressed
3452 elsif Range_Checks_Suppressed (Typ)
3453 and then Overflow_Checks_Suppressed (Typ)
3457 -- Nothing to do if the attribute does not come from source. The
3458 -- internal attributes we generate of this type do not need checks,
3459 -- and furthermore the attempt to check them causes some circular
3460 -- elaboration orders when dealing with packed types.
3462 elsif not Comes_From_Source (N) then
3465 -- If the prefix is a selected component that depends on a discriminant
3466 -- the check may improperly expose a discriminant instead of using
3467 -- the bounds of the object itself. Set the type of the attribute to
3468 -- the base type of the context, so that a check will be imposed when
3469 -- needed (e.g. if the node appears as an index).
3471 elsif Nkind (Prefix (N)) = N_Selected_Component
3472 and then Ekind (Typ) = E_Signed_Integer_Subtype
3473 and then Depends_On_Discriminant (Scalar_Range (Typ))
3475 Set_Etype (N, Base_Type (Typ));
3477 -- Otherwise, replace the attribute node with a type conversion node
3478 -- whose expression is the attribute, retyped to universal integer, and
3479 -- whose subtype mark is the target type. The call to analyze this
3480 -- conversion will set range and overflow checks as required for proper
3481 -- detection of an out of range value.
3484 Set_Etype (N, Universal_Integer);
3485 Set_Analyzed (N, True);
3488 Make_Type_Conversion (Loc,
3489 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
3490 Expression => Relocate_Node (N)));
3492 Analyze_And_Resolve (N, Typ);
3495 end Apply_Universal_Integer_Attribute_Checks;
3497 -------------------------------------
3498 -- Atomic_Synchronization_Disabled --
3499 -------------------------------------
3501 -- Note: internally Disable/Enable_Atomic_Synchronization is implemented
3502 -- using a bogus check called Atomic_Synchronization. This is to make it
3503 -- more convenient to get exactly the same semantics as [Un]Suppress.
3505 function Atomic_Synchronization_Disabled (E : Entity_Id) return Boolean is
3507 -- If debug flag d.e is set, always return False, i.e. all atomic sync
3508 -- looks enabled, since it is never disabled.
3510 if Debug_Flag_Dot_E then
3513 -- If debug flag d.d is set then always return True, i.e. all atomic
3514 -- sync looks disabled, since it always tests True.
3516 elsif Debug_Flag_Dot_D then
3519 -- If entity present, then check result for that entity
3521 elsif Present (E) and then Checks_May_Be_Suppressed (E) then
3522 return Is_Check_Suppressed (E, Atomic_Synchronization);
3524 -- Otherwise result depends on current scope setting
3527 return Scope_Suppress.Suppress (Atomic_Synchronization);
3529 end Atomic_Synchronization_Disabled;
3531 -------------------------------
3532 -- Build_Discriminant_Checks --
3533 -------------------------------
3535 function Build_Discriminant_Checks
3537 T_Typ : Entity_Id) return Node_Id
3539 Loc : constant Source_Ptr := Sloc (N);
3542 Disc_Ent : Entity_Id;
3546 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
3548 ----------------------------------
3549 -- Aggregate_Discriminant_Value --
3550 ----------------------------------
3552 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
3556 -- The aggregate has been normalized with named associations. We use
3557 -- the Chars field to locate the discriminant to take into account
3558 -- discriminants in derived types, which carry the same name as those
3561 Assoc := First (Component_Associations (N));
3562 while Present (Assoc) loop
3563 if Chars (First (Choices (Assoc))) = Chars (Disc) then
3564 return Expression (Assoc);
3570 -- Discriminant must have been found in the loop above
3572 raise Program_Error;
3573 end Aggregate_Discriminant_Val;
3575 -- Start of processing for Build_Discriminant_Checks
3578 -- Loop through discriminants evolving the condition
3581 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
3583 -- For a fully private type, use the discriminants of the parent type
3585 if Is_Private_Type (T_Typ)
3586 and then No (Full_View (T_Typ))
3588 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
3590 Disc_Ent := First_Discriminant (T_Typ);
3593 while Present (Disc) loop
3594 Dval := Node (Disc);
3596 if Nkind (Dval) = N_Identifier
3597 and then Ekind (Entity (Dval)) = E_Discriminant
3599 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
3601 Dval := Duplicate_Subexpr_No_Checks (Dval);
3604 -- If we have an Unchecked_Union node, we can infer the discriminants
3607 if Is_Unchecked_Union (Base_Type (T_Typ)) then
3609 Get_Discriminant_Value (
3610 First_Discriminant (T_Typ),
3612 Stored_Constraint (T_Typ)));
3614 elsif Nkind (N) = N_Aggregate then
3616 Duplicate_Subexpr_No_Checks
3617 (Aggregate_Discriminant_Val (Disc_Ent));
3621 Make_Selected_Component (Loc,
3623 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
3624 Selector_Name => Make_Identifier (Loc, Chars (Disc_Ent)));
3626 Set_Is_In_Discriminant_Check (Dref);
3629 Evolve_Or_Else (Cond,
3632 Right_Opnd => Dval));
3635 Next_Discriminant (Disc_Ent);
3639 end Build_Discriminant_Checks;
3645 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
3652 function Left_Expression (Op : Node_Id) return Node_Id;
3653 -- Return the relevant expression from the left operand of the given
3654 -- short circuit form: this is LO itself, except if LO is a qualified
3655 -- expression, a type conversion, or an expression with actions, in
3656 -- which case this is Left_Expression (Expression (LO)).
3658 ---------------------
3659 -- Left_Expression --
3660 ---------------------
3662 function Left_Expression (Op : Node_Id) return Node_Id is
3663 LE : Node_Id := Left_Opnd (Op);
3665 while Nkind_In (LE, N_Qualified_Expression,
3667 N_Expression_With_Actions)
3669 LE := Expression (LE);
3673 end Left_Expression;
3675 -- Start of processing for Check_Needed
3678 -- Always check if not simple entity
3680 if Nkind (Nod) not in N_Has_Entity
3681 or else not Comes_From_Source (Nod)
3686 -- Look up tree for short circuit
3693 -- Done if out of subexpression (note that we allow generated stuff
3694 -- such as itype declarations in this context, to keep the loop going
3695 -- since we may well have generated such stuff in complex situations.
3696 -- Also done if no parent (probably an error condition, but no point
3697 -- in behaving nasty if we find it).
3700 or else (K not in N_Subexpr and then Comes_From_Source (P))
3704 -- Or/Or Else case, where test is part of the right operand, or is
3705 -- part of one of the actions associated with the right operand, and
3706 -- the left operand is an equality test.
3708 elsif K = N_Op_Or then
3709 exit when N = Right_Opnd (P)
3710 and then Nkind (Left_Expression (P)) = N_Op_Eq;
3712 elsif K = N_Or_Else then
3713 exit when (N = Right_Opnd (P)
3716 and then List_Containing (N) = Actions (P)))
3717 and then Nkind (Left_Expression (P)) = N_Op_Eq;
3719 -- Similar test for the And/And then case, where the left operand
3720 -- is an inequality test.
3722 elsif K = N_Op_And then
3723 exit when N = Right_Opnd (P)
3724 and then Nkind (Left_Expression (P)) = N_Op_Ne;
3726 elsif K = N_And_Then then
3727 exit when (N = Right_Opnd (P)
3730 and then List_Containing (N) = Actions (P)))
3731 and then Nkind (Left_Expression (P)) = N_Op_Ne;
3737 -- If we fall through the loop, then we have a conditional with an
3738 -- appropriate test as its left operand, so look further.
3740 L := Left_Expression (P);
3742 -- L is an "=" or "/=" operator: extract its operands
3744 R := Right_Opnd (L);
3747 -- Left operand of test must match original variable
3749 if Nkind (L) not in N_Has_Entity or else Entity (L) /= Entity (Nod) then
3753 -- Right operand of test must be key value (zero or null)
3756 when Access_Check =>
3757 if not Known_Null (R) then
3761 when Division_Check =>
3762 if not Compile_Time_Known_Value (R)
3763 or else Expr_Value (R) /= Uint_0
3769 raise Program_Error;
3772 -- Here we have the optimizable case, warn if not short-circuited
3774 if K = N_Op_And or else K = N_Op_Or then
3775 Error_Msg_Warn := SPARK_Mode /= On;
3778 when Access_Check =>
3779 if GNATprove_Mode then
3781 ("Constraint_Error might have been raised (access check)",
3785 ("Constraint_Error may be raised (access check)??",
3789 when Division_Check =>
3790 if GNATprove_Mode then
3792 ("Constraint_Error might have been raised (zero divide)",
3796 ("Constraint_Error may be raised (zero divide)??",
3801 raise Program_Error;
3804 if K = N_Op_And then
3805 Error_Msg_N -- CODEFIX
3806 ("use `AND THEN` instead of AND??", P);
3808 Error_Msg_N -- CODEFIX
3809 ("use `OR ELSE` instead of OR??", P);
3812 -- If not short-circuited, we need the check
3816 -- If short-circuited, we can omit the check
3823 -----------------------------------
3824 -- Check_Valid_Lvalue_Subscripts --
3825 -----------------------------------
3827 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
3829 -- Skip this if range checks are suppressed
3831 if Range_Checks_Suppressed (Etype (Expr)) then
3834 -- Only do this check for expressions that come from source. We assume
3835 -- that expander generated assignments explicitly include any necessary
3836 -- checks. Note that this is not just an optimization, it avoids
3837 -- infinite recursions.
3839 elsif not Comes_From_Source (Expr) then
3842 -- For a selected component, check the prefix
3844 elsif Nkind (Expr) = N_Selected_Component then
3845 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
3848 -- Case of indexed component
3850 elsif Nkind (Expr) = N_Indexed_Component then
3851 Apply_Subscript_Validity_Checks (Expr);
3853 -- Prefix may itself be or contain an indexed component, and these
3854 -- subscripts need checking as well.
3856 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
3858 end Check_Valid_Lvalue_Subscripts;
3860 ----------------------------------
3861 -- Null_Exclusion_Static_Checks --
3862 ----------------------------------
3864 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
3865 Error_Node : Node_Id;
3867 Has_Null : constant Boolean := Has_Null_Exclusion (N);
3868 K : constant Node_Kind := Nkind (N);
3873 (Nkind_In (K, N_Component_Declaration,
3874 N_Discriminant_Specification,
3875 N_Function_Specification,
3876 N_Object_Declaration,
3877 N_Parameter_Specification));
3879 if K = N_Function_Specification then
3880 Typ := Etype (Defining_Entity (N));
3882 Typ := Etype (Defining_Identifier (N));
3886 when N_Component_Declaration =>
3887 if Present (Access_Definition (Component_Definition (N))) then
3888 Error_Node := Component_Definition (N);
3890 Error_Node := Subtype_Indication (Component_Definition (N));
3893 when N_Discriminant_Specification =>
3894 Error_Node := Discriminant_Type (N);
3896 when N_Function_Specification =>
3897 Error_Node := Result_Definition (N);
3899 when N_Object_Declaration =>
3900 Error_Node := Object_Definition (N);
3902 when N_Parameter_Specification =>
3903 Error_Node := Parameter_Type (N);
3906 raise Program_Error;
3911 -- Enforce legality rule 3.10 (13): A null exclusion can only be
3912 -- applied to an access [sub]type.
3914 if not Is_Access_Type (Typ) then
3916 ("`NOT NULL` allowed only for an access type", Error_Node);
3918 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
3919 -- be applied to a [sub]type that does not exclude null already.
3921 elsif Can_Never_Be_Null (Typ)
3922 and then Comes_From_Source (Typ)
3925 ("`NOT NULL` not allowed (& already excludes null)",
3930 -- Check that null-excluding objects are always initialized, except for
3931 -- deferred constants, for which the expression will appear in the full
3934 if K = N_Object_Declaration
3935 and then No (Expression (N))
3936 and then not Constant_Present (N)
3937 and then not No_Initialization (N)
3939 -- Add an expression that assigns null. This node is needed by
3940 -- Apply_Compile_Time_Constraint_Error, which will replace this with
3941 -- a Constraint_Error node.
3943 Set_Expression (N, Make_Null (Sloc (N)));
3944 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
3946 Apply_Compile_Time_Constraint_Error
3947 (N => Expression (N),
3949 "(Ada 2005) null-excluding objects must be initialized??",
3950 Reason => CE_Null_Not_Allowed);
3953 -- Check that a null-excluding component, formal or object is not being
3954 -- assigned a null value. Otherwise generate a warning message and
3955 -- replace Expression (N) by an N_Constraint_Error node.
3957 if K /= N_Function_Specification then
3958 Expr := Expression (N);
3960 if Present (Expr) and then Known_Null (Expr) then
3962 when N_Component_Declaration |
3963 N_Discriminant_Specification =>
3964 Apply_Compile_Time_Constraint_Error
3966 Msg => "(Ada 2005) null not allowed "
3967 & "in null-excluding components??",
3968 Reason => CE_Null_Not_Allowed);
3970 when N_Object_Declaration =>
3971 Apply_Compile_Time_Constraint_Error
3973 Msg => "(Ada 2005) null not allowed "
3974 & "in null-excluding objects??",
3975 Reason => CE_Null_Not_Allowed);
3977 when N_Parameter_Specification =>
3978 Apply_Compile_Time_Constraint_Error
3980 Msg => "(Ada 2005) null not allowed "
3981 & "in null-excluding formals??",
3982 Reason => CE_Null_Not_Allowed);
3989 end Null_Exclusion_Static_Checks;
3991 ----------------------------------
3992 -- Conditional_Statements_Begin --
3993 ----------------------------------
3995 procedure Conditional_Statements_Begin is
3997 Saved_Checks_TOS := Saved_Checks_TOS + 1;
3999 -- If stack overflows, kill all checks, that way we know to simply reset
4000 -- the number of saved checks to zero on return. This should never occur
4003 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
4006 -- In the normal case, we just make a new stack entry saving the current
4007 -- number of saved checks for a later restore.
4010 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
4012 if Debug_Flag_CC then
4013 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
4017 end Conditional_Statements_Begin;
4019 --------------------------------
4020 -- Conditional_Statements_End --
4021 --------------------------------
4023 procedure Conditional_Statements_End is
4025 pragma Assert (Saved_Checks_TOS > 0);
4027 -- If the saved checks stack overflowed, then we killed all checks, so
4028 -- setting the number of saved checks back to zero is correct. This
4029 -- should never occur in practice.
4031 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
4032 Num_Saved_Checks := 0;
4034 -- In the normal case, restore the number of saved checks from the top
4038 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
4040 if Debug_Flag_CC then
4041 w ("Conditional_Statements_End: Num_Saved_Checks = ",
4046 Saved_Checks_TOS := Saved_Checks_TOS - 1;
4047 end Conditional_Statements_End;
4049 -------------------------
4050 -- Convert_From_Bignum --
4051 -------------------------
4053 function Convert_From_Bignum (N : Node_Id) return Node_Id is
4054 Loc : constant Source_Ptr := Sloc (N);
4057 pragma Assert (Is_RTE (Etype (N), RE_Bignum));
4059 -- Construct call From Bignum
4062 Make_Function_Call (Loc,
4064 New_Occurrence_Of (RTE (RE_From_Bignum), Loc),
4065 Parameter_Associations => New_List (Relocate_Node (N)));
4066 end Convert_From_Bignum;
4068 -----------------------
4069 -- Convert_To_Bignum --
4070 -----------------------
4072 function Convert_To_Bignum (N : Node_Id) return Node_Id is
4073 Loc : constant Source_Ptr := Sloc (N);
4076 -- Nothing to do if Bignum already except call Relocate_Node
4078 if Is_RTE (Etype (N), RE_Bignum) then
4079 return Relocate_Node (N);
4081 -- Otherwise construct call to To_Bignum, converting the operand to the
4082 -- required Long_Long_Integer form.
4085 pragma Assert (Is_Signed_Integer_Type (Etype (N)));
4087 Make_Function_Call (Loc,
4089 New_Occurrence_Of (RTE (RE_To_Bignum), Loc),
4090 Parameter_Associations => New_List (
4091 Convert_To (Standard_Long_Long_Integer, Relocate_Node (N))));
4093 end Convert_To_Bignum;
4095 ---------------------
4096 -- Determine_Range --
4097 ---------------------
4099 Cache_Size : constant := 2 ** 10;
4100 type Cache_Index is range 0 .. Cache_Size - 1;
4101 -- Determine size of below cache (power of 2 is more efficient)
4103 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
4104 Determine_Range_Cache_V : array (Cache_Index) of Boolean;
4105 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
4106 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
4107 Determine_Range_Cache_Lo_R : array (Cache_Index) of Ureal;
4108 Determine_Range_Cache_Hi_R : array (Cache_Index) of Ureal;
4109 -- The above arrays are used to implement a small direct cache for
4110 -- Determine_Range and Determine_Range_R calls. Because of the way these
4111 -- subprograms recursively traces subexpressions, and because overflow
4112 -- checking calls the routine on the way up the tree, a quadratic behavior
4113 -- can otherwise be encountered in large expressions. The cache entry for
4114 -- node N is stored in the (N mod Cache_Size) entry, and can be validated
4115 -- by checking the actual node value stored there. The Range_Cache_V array
4116 -- records the setting of Assume_Valid for the cache entry.
4118 procedure Determine_Range
4123 Assume_Valid : Boolean := False)
4125 Typ : Entity_Id := Etype (N);
4126 -- Type to use, may get reset to base type for possibly invalid entity
4130 -- Lo and Hi bounds of left operand
4134 -- Lo and Hi bounds of right (or only) operand
4137 -- Temp variable used to hold a bound node
4140 -- High bound of base type of expression
4144 -- Refined values for low and high bounds, after tightening
4147 -- Used in lower level calls to indicate if call succeeded
4149 Cindex : Cache_Index;
4150 -- Used to search cache
4155 function OK_Operands return Boolean;
4156 -- Used for binary operators. Determines the ranges of the left and
4157 -- right operands, and if they are both OK, returns True, and puts
4158 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
4164 function OK_Operands return Boolean is
4167 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
4174 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4178 -- Start of processing for Determine_Range
4181 -- Prevent junk warnings by initializing range variables
4188 -- For temporary constants internally generated to remove side effects
4189 -- we must use the corresponding expression to determine the range of
4190 -- the expression. But note that the expander can also generate
4191 -- constants in other cases, including deferred constants.
4193 if Is_Entity_Name (N)
4194 and then Nkind (Parent (Entity (N))) = N_Object_Declaration
4195 and then Ekind (Entity (N)) = E_Constant
4196 and then Is_Internal_Name (Chars (Entity (N)))
4198 if Present (Expression (Parent (Entity (N)))) then
4200 (Expression (Parent (Entity (N))), OK, Lo, Hi, Assume_Valid);
4202 elsif Present (Full_View (Entity (N))) then
4204 (Expression (Parent (Full_View (Entity (N)))),
4205 OK, Lo, Hi, Assume_Valid);
4213 -- If type is not defined, we can't determine its range
4217 -- We don't deal with anything except discrete types
4219 or else not Is_Discrete_Type (Typ)
4221 -- Ignore type for which an error has been posted, since range in
4222 -- this case may well be a bogosity deriving from the error. Also
4223 -- ignore if error posted on the reference node.
4225 or else Error_Posted (N) or else Error_Posted (Typ)
4231 -- For all other cases, we can determine the range
4235 -- If value is compile time known, then the possible range is the one
4236 -- value that we know this expression definitely has.
4238 if Compile_Time_Known_Value (N) then
4239 Lo := Expr_Value (N);
4244 -- Return if already in the cache
4246 Cindex := Cache_Index (N mod Cache_Size);
4248 if Determine_Range_Cache_N (Cindex) = N
4250 Determine_Range_Cache_V (Cindex) = Assume_Valid
4252 Lo := Determine_Range_Cache_Lo (Cindex);
4253 Hi := Determine_Range_Cache_Hi (Cindex);
4257 -- Otherwise, start by finding the bounds of the type of the expression,
4258 -- the value cannot be outside this range (if it is, then we have an
4259 -- overflow situation, which is a separate check, we are talking here
4260 -- only about the expression value).
4262 -- First a check, never try to find the bounds of a generic type, since
4263 -- these bounds are always junk values, and it is only valid to look at
4264 -- the bounds in an instance.
4266 if Is_Generic_Type (Typ) then
4271 -- First step, change to use base type unless we know the value is valid
4273 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
4274 or else Assume_No_Invalid_Values
4275 or else Assume_Valid
4279 Typ := Underlying_Type (Base_Type (Typ));
4282 -- Retrieve the base type. Handle the case where the base type is a
4283 -- private enumeration type.
4285 Btyp := Base_Type (Typ);
4287 if Is_Private_Type (Btyp) and then Present (Full_View (Btyp)) then
4288 Btyp := Full_View (Btyp);
4291 -- We use the actual bound unless it is dynamic, in which case use the
4292 -- corresponding base type bound if possible. If we can't get a bound
4293 -- then we figure we can't determine the range (a peculiar case, that
4294 -- perhaps cannot happen, but there is no point in bombing in this
4295 -- optimization circuit.
4297 -- First the low bound
4299 Bound := Type_Low_Bound (Typ);
4301 if Compile_Time_Known_Value (Bound) then
4302 Lo := Expr_Value (Bound);
4304 elsif Compile_Time_Known_Value (Type_Low_Bound (Btyp)) then
4305 Lo := Expr_Value (Type_Low_Bound (Btyp));
4312 -- Now the high bound
4314 Bound := Type_High_Bound (Typ);
4316 -- We need the high bound of the base type later on, and this should
4317 -- always be compile time known. Again, it is not clear that this
4318 -- can ever be false, but no point in bombing.
4320 if Compile_Time_Known_Value (Type_High_Bound (Btyp)) then
4321 Hbound := Expr_Value (Type_High_Bound (Btyp));
4329 -- If we have a static subtype, then that may have a tighter bound so
4330 -- use the upper bound of the subtype instead in this case.
4332 if Compile_Time_Known_Value (Bound) then
4333 Hi := Expr_Value (Bound);
4336 -- We may be able to refine this value in certain situations. If any
4337 -- refinement is possible, then Lor and Hir are set to possibly tighter
4338 -- bounds, and OK1 is set to True.
4342 -- For unary plus, result is limited by range of operand
4346 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
4348 -- For unary minus, determine range of operand, and negate it
4352 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4359 -- For binary addition, get range of each operand and do the
4360 -- addition to get the result range.
4364 Lor := Lo_Left + Lo_Right;
4365 Hir := Hi_Left + Hi_Right;
4368 -- Division is tricky. The only case we consider is where the right
4369 -- operand is a positive constant, and in this case we simply divide
4370 -- the bounds of the left operand
4374 if Lo_Right = Hi_Right
4375 and then Lo_Right > 0
4377 Lor := Lo_Left / Lo_Right;
4378 Hir := Hi_Left / Lo_Right;
4384 -- For binary subtraction, get range of each operand and do the worst
4385 -- case subtraction to get the result range.
4387 when N_Op_Subtract =>
4389 Lor := Lo_Left - Hi_Right;
4390 Hir := Hi_Left - Lo_Right;
4393 -- For MOD, if right operand is a positive constant, then result must
4394 -- be in the allowable range of mod results.
4398 if Lo_Right = Hi_Right
4399 and then Lo_Right /= 0
4401 if Lo_Right > 0 then
4403 Hir := Lo_Right - 1;
4405 else -- Lo_Right < 0
4406 Lor := Lo_Right + 1;
4415 -- For REM, if right operand is a positive constant, then result must
4416 -- be in the allowable range of mod results.
4420 if Lo_Right = Hi_Right
4421 and then Lo_Right /= 0
4424 Dval : constant Uint := (abs Lo_Right) - 1;
4427 -- The sign of the result depends on the sign of the
4428 -- dividend (but not on the sign of the divisor, hence
4429 -- the abs operation above).
4449 -- Attribute reference cases
4451 when N_Attribute_Reference =>
4452 case Attribute_Name (N) is
4454 -- For Pos/Val attributes, we can refine the range using the
4455 -- possible range of values of the attribute expression.
4457 when Name_Pos | Name_Val =>
4459 (First (Expressions (N)), OK1, Lor, Hir, Assume_Valid);
4461 -- For Length attribute, use the bounds of the corresponding
4462 -- index type to refine the range.
4466 Atyp : Entity_Id := Etype (Prefix (N));
4474 if Is_Access_Type (Atyp) then
4475 Atyp := Designated_Type (Atyp);
4478 -- For string literal, we know exact value
4480 if Ekind (Atyp) = E_String_Literal_Subtype then
4482 Lo := String_Literal_Length (Atyp);
4483 Hi := String_Literal_Length (Atyp);
4487 -- Otherwise check for expression given
4489 if No (Expressions (N)) then
4493 UI_To_Int (Expr_Value (First (Expressions (N))));
4496 Indx := First_Index (Atyp);
4497 for J in 2 .. Inum loop
4498 Indx := Next_Index (Indx);
4501 -- If the index type is a formal type or derived from
4502 -- one, the bounds are not static.
4504 if Is_Generic_Type (Root_Type (Etype (Indx))) then
4510 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU,
4515 (Type_High_Bound (Etype (Indx)), OK1, UL, UU,
4520 -- The maximum value for Length is the biggest
4521 -- possible gap between the values of the bounds.
4522 -- But of course, this value cannot be negative.
4524 Hir := UI_Max (Uint_0, UU - LL + 1);
4526 -- For constrained arrays, the minimum value for
4527 -- Length is taken from the actual value of the
4528 -- bounds, since the index will be exactly of this
4531 if Is_Constrained (Atyp) then
4532 Lor := UI_Max (Uint_0, UL - LU + 1);
4534 -- For an unconstrained array, the minimum value
4535 -- for length is always zero.
4544 -- No special handling for other attributes
4545 -- Probably more opportunities exist here???
4552 -- For type conversion from one discrete type to another, we can
4553 -- refine the range using the converted value.
4555 when N_Type_Conversion =>
4556 Determine_Range (Expression (N), OK1, Lor, Hir, Assume_Valid);
4558 -- Nothing special to do for all other expression kinds
4566 -- At this stage, if OK1 is true, then we know that the actual result of
4567 -- the computed expression is in the range Lor .. Hir. We can use this
4568 -- to restrict the possible range of results.
4572 -- If the refined value of the low bound is greater than the type
4573 -- low bound, then reset it to the more restrictive value. However,
4574 -- we do NOT do this for the case of a modular type where the
4575 -- possible upper bound on the value is above the base type high
4576 -- bound, because that means the result could wrap.
4579 and then not (Is_Modular_Integer_Type (Typ) and then Hir > Hbound)
4584 -- Similarly, if the refined value of the high bound is less than the
4585 -- value so far, then reset it to the more restrictive value. Again,
4586 -- we do not do this if the refined low bound is negative for a
4587 -- modular type, since this would wrap.
4590 and then not (Is_Modular_Integer_Type (Typ) and then Lor < Uint_0)
4596 -- Set cache entry for future call and we are all done
4598 Determine_Range_Cache_N (Cindex) := N;
4599 Determine_Range_Cache_V (Cindex) := Assume_Valid;
4600 Determine_Range_Cache_Lo (Cindex) := Lo;
4601 Determine_Range_Cache_Hi (Cindex) := Hi;
4604 -- If any exception occurs, it means that we have some bug in the compiler,
4605 -- possibly triggered by a previous error, or by some unforeseen peculiar
4606 -- occurrence. However, this is only an optimization attempt, so there is
4607 -- really no point in crashing the compiler. Instead we just decide, too
4608 -- bad, we can't figure out a range in this case after all.
4613 -- Debug flag K disables this behavior (useful for debugging)
4615 if Debug_Flag_K then
4623 end Determine_Range;
4625 -----------------------
4626 -- Determine_Range_R --
4627 -----------------------
4629 procedure Determine_Range_R
4634 Assume_Valid : Boolean := False)
4636 Typ : Entity_Id := Etype (N);
4637 -- Type to use, may get reset to base type for possibly invalid entity
4641 -- Lo and Hi bounds of left operand
4645 -- Lo and Hi bounds of right (or only) operand
4648 -- Temp variable used to hold a bound node
4651 -- High bound of base type of expression
4655 -- Refined values for low and high bounds, after tightening
4658 -- Used in lower level calls to indicate if call succeeded
4660 Cindex : Cache_Index;
4661 -- Used to search cache
4666 function OK_Operands return Boolean;
4667 -- Used for binary operators. Determines the ranges of the left and
4668 -- right operands, and if they are both OK, returns True, and puts
4669 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
4671 function Round_Machine (B : Ureal) return Ureal;
4672 -- B is a real bound. Round it using mode Round_Even.
4678 function OK_Operands return Boolean is
4681 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
4688 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4696 function Round_Machine (B : Ureal) return Ureal is
4698 return Machine (Typ, B, Round_Even, N);
4701 -- Start of processing for Determine_Range_R
4704 -- Prevent junk warnings by initializing range variables
4711 -- For temporary constants internally generated to remove side effects
4712 -- we must use the corresponding expression to determine the range of
4713 -- the expression. But note that the expander can also generate
4714 -- constants in other cases, including deferred constants.
4716 if Is_Entity_Name (N)
4717 and then Nkind (Parent (Entity (N))) = N_Object_Declaration
4718 and then Ekind (Entity (N)) = E_Constant
4719 and then Is_Internal_Name (Chars (Entity (N)))
4721 if Present (Expression (Parent (Entity (N)))) then
4723 (Expression (Parent (Entity (N))), OK, Lo, Hi, Assume_Valid);
4725 elsif Present (Full_View (Entity (N))) then
4727 (Expression (Parent (Full_View (Entity (N)))),
4728 OK, Lo, Hi, Assume_Valid);
4737 -- If type is not defined, we can't determine its range
4741 -- We don't deal with anything except IEEE floating-point types
4743 or else not Is_Floating_Point_Type (Typ)
4744 or else Float_Rep (Typ) /= IEEE_Binary
4746 -- Ignore type for which an error has been posted, since range in
4747 -- this case may well be a bogosity deriving from the error. Also
4748 -- ignore if error posted on the reference node.
4750 or else Error_Posted (N) or else Error_Posted (Typ)
4756 -- For all other cases, we can determine the range
4760 -- If value is compile time known, then the possible range is the one
4761 -- value that we know this expression definitely has.
4763 if Compile_Time_Known_Value (N) then
4764 Lo := Expr_Value_R (N);
4769 -- Return if already in the cache
4771 Cindex := Cache_Index (N mod Cache_Size);
4773 if Determine_Range_Cache_N (Cindex) = N
4775 Determine_Range_Cache_V (Cindex) = Assume_Valid
4777 Lo := Determine_Range_Cache_Lo_R (Cindex);
4778 Hi := Determine_Range_Cache_Hi_R (Cindex);
4782 -- Otherwise, start by finding the bounds of the type of the expression,
4783 -- the value cannot be outside this range (if it is, then we have an
4784 -- overflow situation, which is a separate check, we are talking here
4785 -- only about the expression value).
4787 -- First a check, never try to find the bounds of a generic type, since
4788 -- these bounds are always junk values, and it is only valid to look at
4789 -- the bounds in an instance.
4791 if Is_Generic_Type (Typ) then
4796 -- First step, change to use base type unless we know the value is valid
4798 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
4799 or else Assume_No_Invalid_Values
4800 or else Assume_Valid
4804 Typ := Underlying_Type (Base_Type (Typ));
4807 -- Retrieve the base type. Handle the case where the base type is a
4810 Btyp := Base_Type (Typ);
4812 if Is_Private_Type (Btyp) and then Present (Full_View (Btyp)) then
4813 Btyp := Full_View (Btyp);
4816 -- We use the actual bound unless it is dynamic, in which case use the
4817 -- corresponding base type bound if possible. If we can't get a bound
4818 -- then we figure we can't determine the range (a peculiar case, that
4819 -- perhaps cannot happen, but there is no point in bombing in this
4820 -- optimization circuit).
4822 -- First the low bound
4824 Bound := Type_Low_Bound (Typ);
4826 if Compile_Time_Known_Value (Bound) then
4827 Lo := Expr_Value_R (Bound);
4829 elsif Compile_Time_Known_Value (Type_Low_Bound (Btyp)) then
4830 Lo := Expr_Value_R (Type_Low_Bound (Btyp));
4837 -- Now the high bound
4839 Bound := Type_High_Bound (Typ);
4841 -- We need the high bound of the base type later on, and this should
4842 -- always be compile time known. Again, it is not clear that this
4843 -- can ever be false, but no point in bombing.
4845 if Compile_Time_Known_Value (Type_High_Bound (Btyp)) then
4846 Hbound := Expr_Value_R (Type_High_Bound (Btyp));
4854 -- If we have a static subtype, then that may have a tighter bound so
4855 -- use the upper bound of the subtype instead in this case.
4857 if Compile_Time_Known_Value (Bound) then
4858 Hi := Expr_Value_R (Bound);
4861 -- We may be able to refine this value in certain situations. If any
4862 -- refinement is possible, then Lor and Hir are set to possibly tighter
4863 -- bounds, and OK1 is set to True.
4867 -- For unary plus, result is limited by range of operand
4871 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
4873 -- For unary minus, determine range of operand, and negate it
4877 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4884 -- For binary addition, get range of each operand and do the
4885 -- addition to get the result range.
4889 Lor := Round_Machine (Lo_Left + Lo_Right);
4890 Hir := Round_Machine (Hi_Left + Hi_Right);
4893 -- For binary subtraction, get range of each operand and do the worst
4894 -- case subtraction to get the result range.
4896 when N_Op_Subtract =>
4898 Lor := Round_Machine (Lo_Left - Hi_Right);
4899 Hir := Round_Machine (Hi_Left - Lo_Right);
4902 -- For multiplication, get range of each operand and do the
4903 -- four multiplications to get the result range.
4905 when N_Op_Multiply =>
4908 M1 : constant Ureal := Round_Machine (Lo_Left * Lo_Right);
4909 M2 : constant Ureal := Round_Machine (Lo_Left * Hi_Right);
4910 M3 : constant Ureal := Round_Machine (Hi_Left * Lo_Right);
4911 M4 : constant Ureal := Round_Machine (Hi_Left * Hi_Right);
4913 Lor := UR_Min (UR_Min (M1, M2), UR_Min (M3, M4));
4914 Hir := UR_Max (UR_Max (M1, M2), UR_Max (M3, M4));
4918 -- For division, consider separately the cases where the right
4919 -- operand is positive or negative. Otherwise, the right operand
4920 -- can be arbitrarily close to zero, so the result is likely to
4921 -- be unbounded in one direction, do not attempt to compute it.
4926 -- Right operand is positive
4928 if Lo_Right > Ureal_0 then
4930 -- If the low bound of the left operand is negative, obtain
4931 -- the overall low bound by dividing it by the smallest
4932 -- value of the right operand, and otherwise by the largest
4933 -- value of the right operand.
4935 if Lo_Left < Ureal_0 then
4936 Lor := Round_Machine (Lo_Left / Lo_Right);
4938 Lor := Round_Machine (Lo_Left / Hi_Right);
4941 -- If the high bound of the left operand is negative, obtain
4942 -- the overall high bound by dividing it by the largest
4943 -- value of the right operand, and otherwise by the
4944 -- smallest value of the right operand.
4946 if Hi_Left < Ureal_0 then
4947 Hir := Round_Machine (Hi_Left / Hi_Right);
4949 Hir := Round_Machine (Hi_Left / Lo_Right);
4952 -- Right operand is negative
4954 elsif Hi_Right < Ureal_0 then
4956 -- If the low bound of the left operand is negative, obtain
4957 -- the overall low bound by dividing it by the largest
4958 -- value of the right operand, and otherwise by the smallest
4959 -- value of the right operand.
4961 if Lo_Left < Ureal_0 then
4962 Lor := Round_Machine (Lo_Left / Hi_Right);
4964 Lor := Round_Machine (Lo_Left / Lo_Right);
4967 -- If the high bound of the left operand is negative, obtain
4968 -- the overall high bound by dividing it by the smallest
4969 -- value of the right operand, and otherwise by the
4970 -- largest value of the right operand.
4972 if Hi_Left < Ureal_0 then
4973 Hir := Round_Machine (Hi_Left / Lo_Right);
4975 Hir := Round_Machine (Hi_Left / Hi_Right);
4983 -- For type conversion from one floating-point type to another, we
4984 -- can refine the range using the converted value.
4986 when N_Type_Conversion =>
4987 Determine_Range_R (Expression (N), OK1, Lor, Hir, Assume_Valid);
4989 -- Nothing special to do for all other expression kinds
4997 -- At this stage, if OK1 is true, then we know that the actual result of
4998 -- the computed expression is in the range Lor .. Hir. We can use this
4999 -- to restrict the possible range of results.
5003 -- If the refined value of the low bound is greater than the type
5004 -- low bound, then reset it to the more restrictive value.
5010 -- Similarly, if the refined value of the high bound is less than the
5011 -- value so far, then reset it to the more restrictive value.
5018 -- Set cache entry for future call and we are all done
5020 Determine_Range_Cache_N (Cindex) := N;
5021 Determine_Range_Cache_V (Cindex) := Assume_Valid;
5022 Determine_Range_Cache_Lo_R (Cindex) := Lo;
5023 Determine_Range_Cache_Hi_R (Cindex) := Hi;
5026 -- If any exception occurs, it means that we have some bug in the compiler,
5027 -- possibly triggered by a previous error, or by some unforeseen peculiar
5028 -- occurrence. However, this is only an optimization attempt, so there is
5029 -- really no point in crashing the compiler. Instead we just decide, too
5030 -- bad, we can't figure out a range in this case after all.
5035 -- Debug flag K disables this behavior (useful for debugging)
5037 if Debug_Flag_K then
5045 end Determine_Range_R;
5047 ------------------------------------
5048 -- Discriminant_Checks_Suppressed --
5049 ------------------------------------
5051 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
5054 if Is_Unchecked_Union (E) then
5056 elsif Checks_May_Be_Suppressed (E) then
5057 return Is_Check_Suppressed (E, Discriminant_Check);
5061 return Scope_Suppress.Suppress (Discriminant_Check);
5062 end Discriminant_Checks_Suppressed;
5064 --------------------------------
5065 -- Division_Checks_Suppressed --
5066 --------------------------------
5068 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
5070 if Present (E) and then Checks_May_Be_Suppressed (E) then
5071 return Is_Check_Suppressed (E, Division_Check);
5073 return Scope_Suppress.Suppress (Division_Check);
5075 end Division_Checks_Suppressed;
5077 --------------------------------------
5078 -- Duplicated_Tag_Checks_Suppressed --
5079 --------------------------------------
5081 function Duplicated_Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
5083 if Present (E) and then Checks_May_Be_Suppressed (E) then
5084 return Is_Check_Suppressed (E, Duplicated_Tag_Check);
5086 return Scope_Suppress.Suppress (Duplicated_Tag_Check);
5088 end Duplicated_Tag_Checks_Suppressed;
5090 -----------------------------------
5091 -- Elaboration_Checks_Suppressed --
5092 -----------------------------------
5094 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
5096 -- The complication in this routine is that if we are in the dynamic
5097 -- model of elaboration, we also check All_Checks, since All_Checks
5098 -- does not set Elaboration_Check explicitly.
5101 if Kill_Elaboration_Checks (E) then
5104 elsif Checks_May_Be_Suppressed (E) then
5105 if Is_Check_Suppressed (E, Elaboration_Check) then
5107 elsif Dynamic_Elaboration_Checks then
5108 return Is_Check_Suppressed (E, All_Checks);
5115 if Scope_Suppress.Suppress (Elaboration_Check) then
5117 elsif Dynamic_Elaboration_Checks then
5118 return Scope_Suppress.Suppress (All_Checks);
5122 end Elaboration_Checks_Suppressed;
5124 ---------------------------
5125 -- Enable_Overflow_Check --
5126 ---------------------------
5128 procedure Enable_Overflow_Check (N : Node_Id) is
5129 Typ : constant Entity_Id := Base_Type (Etype (N));
5130 Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
5138 Do_Ovflow_Check : Boolean;
5141 if Debug_Flag_CC then
5142 w ("Enable_Overflow_Check for node ", Int (N));
5143 Write_Str (" Source location = ");
5148 -- No check if overflow checks suppressed for type of node
5150 if Overflow_Checks_Suppressed (Etype (N)) then
5153 -- Nothing to do for unsigned integer types, which do not overflow
5155 elsif Is_Modular_Integer_Type (Typ) then
5159 -- This is the point at which processing for STRICT mode diverges
5160 -- from processing for MINIMIZED/ELIMINATED modes. This divergence is
5161 -- probably more extreme that it needs to be, but what is going on here
5162 -- is that when we introduced MINIMIZED/ELIMINATED modes, we wanted
5163 -- to leave the processing for STRICT mode untouched. There were
5164 -- two reasons for this. First it avoided any incompatible change of
5165 -- behavior. Second, it guaranteed that STRICT mode continued to be
5168 -- The big difference is that in STRICT mode there is a fair amount of
5169 -- circuitry to try to avoid setting the Do_Overflow_Check flag if we
5170 -- know that no check is needed. We skip all that in the two new modes,
5171 -- since really overflow checking happens over a whole subtree, and we
5172 -- do the corresponding optimizations later on when applying the checks.
5174 if Mode in Minimized_Or_Eliminated then
5175 if not (Overflow_Checks_Suppressed (Etype (N)))
5176 and then not (Is_Entity_Name (N)
5177 and then Overflow_Checks_Suppressed (Entity (N)))
5179 Activate_Overflow_Check (N);
5182 if Debug_Flag_CC then
5183 w ("Minimized/Eliminated mode");
5189 -- Remainder of processing is for STRICT case, and is unchanged from
5190 -- earlier versions preceding the addition of MINIMIZED/ELIMINATED.
5192 -- Nothing to do if the range of the result is known OK. We skip this
5193 -- for conversions, since the caller already did the check, and in any
5194 -- case the condition for deleting the check for a type conversion is
5197 if Nkind (N) /= N_Type_Conversion then
5198 Determine_Range (N, OK, Lo, Hi, Assume_Valid => True);
5200 -- Note in the test below that we assume that the range is not OK
5201 -- if a bound of the range is equal to that of the type. That's not
5202 -- quite accurate but we do this for the following reasons:
5204 -- a) The way that Determine_Range works, it will typically report
5205 -- the bounds of the value as being equal to the bounds of the
5206 -- type, because it either can't tell anything more precise, or
5207 -- does not think it is worth the effort to be more precise.
5209 -- b) It is very unusual to have a situation in which this would
5210 -- generate an unnecessary overflow check (an example would be
5211 -- a subtype with a range 0 .. Integer'Last - 1 to which the
5212 -- literal value one is added).
5214 -- c) The alternative is a lot of special casing in this routine
5215 -- which would partially duplicate Determine_Range processing.
5218 Do_Ovflow_Check := True;
5220 -- Note that the following checks are quite deliberately > and <
5221 -- rather than >= and <= as explained above.
5223 if Lo > Expr_Value (Type_Low_Bound (Typ))
5225 Hi < Expr_Value (Type_High_Bound (Typ))
5227 Do_Ovflow_Check := False;
5229 -- Despite the comments above, it is worth dealing specially with
5230 -- division specially. The only case where integer division can
5231 -- overflow is (largest negative number) / (-1). So we will do
5232 -- an extra range analysis to see if this is possible.
5234 elsif Nkind (N) = N_Op_Divide then
5236 (Left_Opnd (N), OK, Lo, Hi, Assume_Valid => True);
5238 if OK and then Lo > Expr_Value (Type_Low_Bound (Typ)) then
5239 Do_Ovflow_Check := False;
5243 (Right_Opnd (N), OK, Lo, Hi, Assume_Valid => True);
5245 if OK and then (Lo > Uint_Minus_1
5249 Do_Ovflow_Check := False;
5254 -- If no overflow check required, we are done
5256 if not Do_Ovflow_Check then
5257 if Debug_Flag_CC then
5258 w ("No overflow check required");
5266 -- If not in optimizing mode, set flag and we are done. We are also done
5267 -- (and just set the flag) if the type is not a discrete type, since it
5268 -- is not worth the effort to eliminate checks for other than discrete
5269 -- types. In addition, we take this same path if we have stored the
5270 -- maximum number of checks possible already (a very unlikely situation,
5271 -- but we do not want to blow up).
5273 if Optimization_Level = 0
5274 or else not Is_Discrete_Type (Etype (N))
5275 or else Num_Saved_Checks = Saved_Checks'Last
5277 Activate_Overflow_Check (N);
5279 if Debug_Flag_CC then
5280 w ("Optimization off");
5286 -- Otherwise evaluate and check the expression
5291 Target_Type => Empty,
5297 if Debug_Flag_CC then
5298 w ("Called Find_Check");
5302 w (" Check_Num = ", Chk);
5303 w (" Ent = ", Int (Ent));
5304 Write_Str (" Ofs = ");
5309 -- If check is not of form to optimize, then set flag and we are done
5312 Activate_Overflow_Check (N);
5316 -- If check is already performed, then return without setting flag
5319 if Debug_Flag_CC then
5320 w ("Check suppressed!");
5326 -- Here we will make a new entry for the new check
5328 Activate_Overflow_Check (N);
5329 Num_Saved_Checks := Num_Saved_Checks + 1;
5330 Saved_Checks (Num_Saved_Checks) :=
5335 Target_Type => Empty);
5337 if Debug_Flag_CC then
5338 w ("Make new entry, check number = ", Num_Saved_Checks);
5339 w (" Entity = ", Int (Ent));
5340 Write_Str (" Offset = ");
5342 w (" Check_Type = O");
5343 w (" Target_Type = Empty");
5346 -- If we get an exception, then something went wrong, probably because of
5347 -- an error in the structure of the tree due to an incorrect program. Or
5348 -- it may be a bug in the optimization circuit. In either case the safest
5349 -- thing is simply to set the check flag unconditionally.
5353 Activate_Overflow_Check (N);
5355 if Debug_Flag_CC then
5356 w (" exception occurred, overflow flag set");
5360 end Enable_Overflow_Check;
5362 ------------------------
5363 -- Enable_Range_Check --
5364 ------------------------
5366 procedure Enable_Range_Check (N : Node_Id) is
5375 -- Return if unchecked type conversion with range check killed. In this
5376 -- case we never set the flag (that's what Kill_Range_Check is about).
5378 if Nkind (N) = N_Unchecked_Type_Conversion
5379 and then Kill_Range_Check (N)
5384 -- Do not set range check flag if parent is assignment statement or
5385 -- object declaration with Suppress_Assignment_Checks flag set
5387 if Nkind_In (Parent (N), N_Assignment_Statement, N_Object_Declaration)
5388 and then Suppress_Assignment_Checks (Parent (N))
5393 -- Check for various cases where we should suppress the range check
5395 -- No check if range checks suppressed for type of node
5397 if Present (Etype (N)) and then Range_Checks_Suppressed (Etype (N)) then
5400 -- No check if node is an entity name, and range checks are suppressed
5401 -- for this entity, or for the type of this entity.
5403 elsif Is_Entity_Name (N)
5404 and then (Range_Checks_Suppressed (Entity (N))
5405 or else Range_Checks_Suppressed (Etype (Entity (N))))
5409 -- No checks if index of array, and index checks are suppressed for
5410 -- the array object or the type of the array.
5412 elsif Nkind (Parent (N)) = N_Indexed_Component then
5414 Pref : constant Node_Id := Prefix (Parent (N));
5416 if Is_Entity_Name (Pref)
5417 and then Index_Checks_Suppressed (Entity (Pref))
5420 elsif Index_Checks_Suppressed (Etype (Pref)) then
5426 -- Debug trace output
5428 if Debug_Flag_CC then
5429 w ("Enable_Range_Check for node ", Int (N));
5430 Write_Str (" Source location = ");
5435 -- If not in optimizing mode, set flag and we are done. We are also done
5436 -- (and just set the flag) if the type is not a discrete type, since it
5437 -- is not worth the effort to eliminate checks for other than discrete
5438 -- types. In addition, we take this same path if we have stored the
5439 -- maximum number of checks possible already (a very unlikely situation,
5440 -- but we do not want to blow up).
5442 if Optimization_Level = 0
5443 or else No (Etype (N))
5444 or else not Is_Discrete_Type (Etype (N))
5445 or else Num_Saved_Checks = Saved_Checks'Last
5447 Activate_Range_Check (N);
5449 if Debug_Flag_CC then
5450 w ("Optimization off");
5456 -- Otherwise find out the target type
5460 -- For assignment, use left side subtype
5462 if Nkind (P) = N_Assignment_Statement
5463 and then Expression (P) = N
5465 Ttyp := Etype (Name (P));
5467 -- For indexed component, use subscript subtype
5469 elsif Nkind (P) = N_Indexed_Component then
5476 Atyp := Etype (Prefix (P));
5478 if Is_Access_Type (Atyp) then
5479 Atyp := Designated_Type (Atyp);
5481 -- If the prefix is an access to an unconstrained array,
5482 -- perform check unconditionally: it depends on the bounds of
5483 -- an object and we cannot currently recognize whether the test
5484 -- may be redundant.
5486 if not Is_Constrained (Atyp) then
5487 Activate_Range_Check (N);
5491 -- Ditto if the prefix is an explicit dereference whose designated
5492 -- type is unconstrained.
5494 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
5495 and then not Is_Constrained (Atyp)
5497 Activate_Range_Check (N);
5501 Indx := First_Index (Atyp);
5502 Subs := First (Expressions (P));
5505 Ttyp := Etype (Indx);
5514 -- For now, ignore all other cases, they are not so interesting
5517 if Debug_Flag_CC then
5518 w (" target type not found, flag set");
5521 Activate_Range_Check (N);
5525 -- Evaluate and check the expression
5530 Target_Type => Ttyp,
5536 if Debug_Flag_CC then
5537 w ("Called Find_Check");
5538 w ("Target_Typ = ", Int (Ttyp));
5542 w (" Check_Num = ", Chk);
5543 w (" Ent = ", Int (Ent));
5544 Write_Str (" Ofs = ");
5549 -- If check is not of form to optimize, then set flag and we are done
5552 if Debug_Flag_CC then
5553 w (" expression not of optimizable type, flag set");
5556 Activate_Range_Check (N);
5560 -- If check is already performed, then return without setting flag
5563 if Debug_Flag_CC then
5564 w ("Check suppressed!");
5570 -- Here we will make a new entry for the new check
5572 Activate_Range_Check (N);
5573 Num_Saved_Checks := Num_Saved_Checks + 1;
5574 Saved_Checks (Num_Saved_Checks) :=
5579 Target_Type => Ttyp);
5581 if Debug_Flag_CC then
5582 w ("Make new entry, check number = ", Num_Saved_Checks);
5583 w (" Entity = ", Int (Ent));
5584 Write_Str (" Offset = ");
5586 w (" Check_Type = R");
5587 w (" Target_Type = ", Int (Ttyp));
5588 pg (Union_Id (Ttyp));
5591 -- If we get an exception, then something went wrong, probably because of
5592 -- an error in the structure of the tree due to an incorrect program. Or
5593 -- it may be a bug in the optimization circuit. In either case the safest
5594 -- thing is simply to set the check flag unconditionally.
5598 Activate_Range_Check (N);
5600 if Debug_Flag_CC then
5601 w (" exception occurred, range flag set");
5605 end Enable_Range_Check;
5611 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
5612 Typ : constant Entity_Id := Etype (Expr);
5615 -- Ignore call if we are not doing any validity checking
5617 if not Validity_Checks_On then
5620 -- Ignore call if range or validity checks suppressed on entity or type
5622 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
5625 -- No check required if expression is from the expander, we assume the
5626 -- expander will generate whatever checks are needed. Note that this is
5627 -- not just an optimization, it avoids infinite recursions.
5629 -- Unchecked conversions must be checked, unless they are initialized
5630 -- scalar values, as in a component assignment in an init proc.
5632 -- In addition, we force a check if Force_Validity_Checks is set
5634 elsif not Comes_From_Source (Expr)
5635 and then not Force_Validity_Checks
5636 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
5637 or else Kill_Range_Check (Expr))
5641 -- No check required if expression is known to have valid value
5643 elsif Expr_Known_Valid (Expr) then
5646 -- Ignore case of enumeration with holes where the flag is set not to
5647 -- worry about holes, since no special validity check is needed
5649 elsif Is_Enumeration_Type (Typ)
5650 and then Has_Non_Standard_Rep (Typ)
5655 -- No check required on the left-hand side of an assignment
5657 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
5658 and then Expr = Name (Parent (Expr))
5662 -- No check on a universal real constant. The context will eventually
5663 -- convert it to a machine number for some target type, or report an
5666 elsif Nkind (Expr) = N_Real_Literal
5667 and then Etype (Expr) = Universal_Real
5671 -- If the expression denotes a component of a packed boolean array,
5672 -- no possible check applies. We ignore the old ACATS chestnuts that
5673 -- involve Boolean range True..True.
5675 -- Note: validity checks are generated for expressions that yield a
5676 -- scalar type, when it is possible to create a value that is outside of
5677 -- the type. If this is a one-bit boolean no such value exists. This is
5678 -- an optimization, and it also prevents compiler blowing up during the
5679 -- elaboration of improperly expanded packed array references.
5681 elsif Nkind (Expr) = N_Indexed_Component
5682 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
5683 and then Root_Type (Etype (Expr)) = Standard_Boolean
5687 -- For an expression with actions, we want to insert the validity check
5688 -- on the final Expression.
5690 elsif Nkind (Expr) = N_Expression_With_Actions then
5691 Ensure_Valid (Expression (Expr));
5694 -- An annoying special case. If this is an out parameter of a scalar
5695 -- type, then the value is not going to be accessed, therefore it is
5696 -- inappropriate to do any validity check at the call site.
5699 -- Only need to worry about scalar types
5701 if Is_Scalar_Type (Typ) then
5711 -- Find actual argument (which may be a parameter association)
5712 -- and the parent of the actual argument (the call statement)
5717 if Nkind (P) = N_Parameter_Association then
5722 -- Only need to worry if we are argument of a procedure call
5723 -- since functions don't have out parameters. If this is an
5724 -- indirect or dispatching call, get signature from the
5727 if Nkind (P) = N_Procedure_Call_Statement then
5728 L := Parameter_Associations (P);
5730 if Is_Entity_Name (Name (P)) then
5731 E := Entity (Name (P));
5733 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
5734 E := Etype (Name (P));
5737 -- Only need to worry if there are indeed actuals, and if
5738 -- this could be a procedure call, otherwise we cannot get a
5739 -- match (either we are not an argument, or the mode of the
5740 -- formal is not OUT). This test also filters out the
5743 if Is_Non_Empty_List (L) and then Is_Subprogram (E) then
5745 -- This is the loop through parameters, looking for an
5746 -- OUT parameter for which we are the argument.
5748 F := First_Formal (E);
5750 while Present (F) loop
5751 if Ekind (F) = E_Out_Parameter and then A = N then
5764 -- If this is a boolean expression, only its elementary operands need
5765 -- checking: if they are valid, a boolean or short-circuit operation
5766 -- with them will be valid as well.
5768 if Base_Type (Typ) = Standard_Boolean
5770 (Nkind (Expr) in N_Op or else Nkind (Expr) in N_Short_Circuit)
5775 -- If we fall through, a validity check is required
5777 Insert_Valid_Check (Expr);
5779 if Is_Entity_Name (Expr)
5780 and then Safe_To_Capture_Value (Expr, Entity (Expr))
5782 Set_Is_Known_Valid (Entity (Expr));
5786 ----------------------
5787 -- Expr_Known_Valid --
5788 ----------------------
5790 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
5791 Typ : constant Entity_Id := Etype (Expr);
5794 -- Non-scalar types are always considered valid, since they never give
5795 -- rise to the issues of erroneous or bounded error behavior that are
5796 -- the concern. In formal reference manual terms the notion of validity
5797 -- only applies to scalar types. Note that even when packed arrays are
5798 -- represented using modular types, they are still arrays semantically,
5799 -- so they are also always valid (in particular, the unused bits can be
5800 -- random rubbish without affecting the validity of the array value).
5802 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Impl_Type (Typ) then
5805 -- If no validity checking, then everything is considered valid
5807 elsif not Validity_Checks_On then
5810 -- Floating-point types are considered valid unless floating-point
5811 -- validity checks have been specifically turned on.
5813 elsif Is_Floating_Point_Type (Typ)
5814 and then not Validity_Check_Floating_Point
5818 -- If the expression is the value of an object that is known to be
5819 -- valid, then clearly the expression value itself is valid.
5821 elsif Is_Entity_Name (Expr)
5822 and then Is_Known_Valid (Entity (Expr))
5824 -- Exclude volatile variables
5826 and then not Treat_As_Volatile (Entity (Expr))
5830 -- References to discriminants are always considered valid. The value
5831 -- of a discriminant gets checked when the object is built. Within the
5832 -- record, we consider it valid, and it is important to do so, since
5833 -- otherwise we can try to generate bogus validity checks which
5834 -- reference discriminants out of scope. Discriminants of concurrent
5835 -- types are excluded for the same reason.
5837 elsif Is_Entity_Name (Expr)
5838 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
5842 -- If the type is one for which all values are known valid, then we are
5843 -- sure that the value is valid except in the slightly odd case where
5844 -- the expression is a reference to a variable whose size has been
5845 -- explicitly set to a value greater than the object size.
5847 elsif Is_Known_Valid (Typ) then
5848 if Is_Entity_Name (Expr)
5849 and then Ekind (Entity (Expr)) = E_Variable
5850 and then Esize (Entity (Expr)) > Esize (Typ)
5857 -- Integer and character literals always have valid values, where
5858 -- appropriate these will be range checked in any case.
5860 elsif Nkind_In (Expr, N_Integer_Literal, N_Character_Literal) then
5863 -- Real literals are assumed to be valid in VM targets
5865 elsif VM_Target /= No_VM and then Nkind (Expr) = N_Real_Literal then
5868 -- If we have a type conversion or a qualification of a known valid
5869 -- value, then the result will always be valid.
5871 elsif Nkind_In (Expr, N_Type_Conversion, N_Qualified_Expression) then
5872 return Expr_Known_Valid (Expression (Expr));
5874 -- Case of expression is a non-floating-point operator. In this case we
5875 -- can assume the result is valid the generated code for the operator
5876 -- will include whatever checks are needed (e.g. range checks) to ensure
5877 -- validity. This assumption does not hold for the floating-point case,
5878 -- since floating-point operators can generate Infinite or NaN results
5879 -- which are considered invalid.
5881 -- Historical note: in older versions, the exemption of floating-point
5882 -- types from this assumption was done only in cases where the parent
5883 -- was an assignment, function call or parameter association. Presumably
5884 -- the idea was that in other contexts, the result would be checked
5885 -- elsewhere, but this list of cases was missing tests (at least the
5886 -- N_Object_Declaration case, as shown by a reported missing validity
5887 -- check), and it is not clear why function calls but not procedure
5888 -- calls were tested for. It really seems more accurate and much
5889 -- safer to recognize that expressions which are the result of a
5890 -- floating-point operator can never be assumed to be valid.
5892 elsif Nkind (Expr) in N_Op and then not Is_Floating_Point_Type (Typ) then
5895 -- The result of a membership test is always valid, since it is true or
5896 -- false, there are no other possibilities.
5898 elsif Nkind (Expr) in N_Membership_Test then
5901 -- For all other cases, we do not know the expression is valid
5906 end Expr_Known_Valid;
5912 procedure Find_Check
5914 Check_Type : Character;
5915 Target_Type : Entity_Id;
5916 Entry_OK : out Boolean;
5917 Check_Num : out Nat;
5918 Ent : out Entity_Id;
5921 function Within_Range_Of
5922 (Target_Type : Entity_Id;
5923 Check_Type : Entity_Id) return Boolean;
5924 -- Given a requirement for checking a range against Target_Type, and
5925 -- and a range Check_Type against which a check has already been made,
5926 -- determines if the check against check type is sufficient to ensure
5927 -- that no check against Target_Type is required.
5929 ---------------------
5930 -- Within_Range_Of --
5931 ---------------------
5933 function Within_Range_Of
5934 (Target_Type : Entity_Id;
5935 Check_Type : Entity_Id) return Boolean
5938 if Target_Type = Check_Type then
5943 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
5944 Thi : constant Node_Id := Type_High_Bound (Target_Type);
5945 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
5946 Chi : constant Node_Id := Type_High_Bound (Check_Type);
5950 or else (Compile_Time_Known_Value (Tlo)
5952 Compile_Time_Known_Value (Clo)
5954 Expr_Value (Clo) >= Expr_Value (Tlo)))
5957 or else (Compile_Time_Known_Value (Thi)
5959 Compile_Time_Known_Value (Chi)
5961 Expr_Value (Chi) <= Expr_Value (Clo)))
5969 end Within_Range_Of;
5971 -- Start of processing for Find_Check
5974 -- Establish default, in case no entry is found
5978 -- Case of expression is simple entity reference
5980 if Is_Entity_Name (Expr) then
5981 Ent := Entity (Expr);
5984 -- Case of expression is entity + known constant
5986 elsif Nkind (Expr) = N_Op_Add
5987 and then Compile_Time_Known_Value (Right_Opnd (Expr))
5988 and then Is_Entity_Name (Left_Opnd (Expr))
5990 Ent := Entity (Left_Opnd (Expr));
5991 Ofs := Expr_Value (Right_Opnd (Expr));
5993 -- Case of expression is entity - known constant
5995 elsif Nkind (Expr) = N_Op_Subtract
5996 and then Compile_Time_Known_Value (Right_Opnd (Expr))
5997 and then Is_Entity_Name (Left_Opnd (Expr))
5999 Ent := Entity (Left_Opnd (Expr));
6000 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
6002 -- Any other expression is not of the right form
6011 -- Come here with expression of appropriate form, check if entity is an
6012 -- appropriate one for our purposes.
6014 if (Ekind (Ent) = E_Variable
6015 or else Is_Constant_Object (Ent))
6016 and then not Is_Library_Level_Entity (Ent)
6024 -- See if there is matching check already
6026 for J in reverse 1 .. Num_Saved_Checks loop
6028 SC : Saved_Check renames Saved_Checks (J);
6030 if SC.Killed = False
6031 and then SC.Entity = Ent
6032 and then SC.Offset = Ofs
6033 and then SC.Check_Type = Check_Type
6034 and then Within_Range_Of (Target_Type, SC.Target_Type)
6042 -- If we fall through entry was not found
6047 ---------------------------------
6048 -- Generate_Discriminant_Check --
6049 ---------------------------------
6051 -- Note: the code for this procedure is derived from the
6052 -- Emit_Discriminant_Check Routine in trans.c.
6054 procedure Generate_Discriminant_Check (N : Node_Id) is
6055 Loc : constant Source_Ptr := Sloc (N);
6056 Pref : constant Node_Id := Prefix (N);
6057 Sel : constant Node_Id := Selector_Name (N);
6059 Orig_Comp : constant Entity_Id :=
6060 Original_Record_Component (Entity (Sel));
6061 -- The original component to be checked
6063 Discr_Fct : constant Entity_Id :=
6064 Discriminant_Checking_Func (Orig_Comp);
6065 -- The discriminant checking function
6068 -- One discriminant to be checked in the type
6070 Real_Discr : Entity_Id;
6071 -- Actual discriminant in the call
6073 Pref_Type : Entity_Id;
6074 -- Type of relevant prefix (ignoring private/access stuff)
6077 -- List of arguments for function call
6080 -- Keep track of the formal corresponding to the actual we build for
6081 -- each discriminant, in order to be able to perform the necessary type
6085 -- Selected component reference for checking function argument
6088 Pref_Type := Etype (Pref);
6090 -- Force evaluation of the prefix, so that it does not get evaluated
6091 -- twice (once for the check, once for the actual reference). Such a
6092 -- double evaluation is always a potential source of inefficiency, and
6093 -- is functionally incorrect in the volatile case, or when the prefix
6094 -- may have side-effects. A non-volatile entity or a component of a
6095 -- non-volatile entity requires no evaluation.
6097 if Is_Entity_Name (Pref) then
6098 if Treat_As_Volatile (Entity (Pref)) then
6099 Force_Evaluation (Pref, Name_Req => True);
6102 elsif Treat_As_Volatile (Etype (Pref)) then
6103 Force_Evaluation (Pref, Name_Req => True);
6105 elsif Nkind (Pref) = N_Selected_Component
6106 and then Is_Entity_Name (Prefix (Pref))
6111 Force_Evaluation (Pref, Name_Req => True);
6114 -- For a tagged type, use the scope of the original component to
6115 -- obtain the type, because ???
6117 if Is_Tagged_Type (Scope (Orig_Comp)) then
6118 Pref_Type := Scope (Orig_Comp);
6120 -- For an untagged derived type, use the discriminants of the parent
6121 -- which have been renamed in the derivation, possibly by a one-to-many
6122 -- discriminant constraint. For untagged type, initially get the Etype
6126 if Is_Derived_Type (Pref_Type)
6127 and then Number_Discriminants (Pref_Type) /=
6128 Number_Discriminants (Etype (Base_Type (Pref_Type)))
6130 Pref_Type := Etype (Base_Type (Pref_Type));
6134 -- We definitely should have a checking function, This routine should
6135 -- not be called if no discriminant checking function is present.
6137 pragma Assert (Present (Discr_Fct));
6139 -- Create the list of the actual parameters for the call. This list
6140 -- is the list of the discriminant fields of the record expression to
6141 -- be discriminant checked.
6144 Formal := First_Formal (Discr_Fct);
6145 Discr := First_Discriminant (Pref_Type);
6146 while Present (Discr) loop
6148 -- If we have a corresponding discriminant field, and a parent
6149 -- subtype is present, then we want to use the corresponding
6150 -- discriminant since this is the one with the useful value.
6152 if Present (Corresponding_Discriminant (Discr))
6153 and then Ekind (Pref_Type) = E_Record_Type
6154 and then Present (Parent_Subtype (Pref_Type))
6156 Real_Discr := Corresponding_Discriminant (Discr);
6158 Real_Discr := Discr;
6161 -- Construct the reference to the discriminant
6164 Make_Selected_Component (Loc,
6166 Unchecked_Convert_To (Pref_Type,
6167 Duplicate_Subexpr (Pref)),
6168 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
6170 -- Manually analyze and resolve this selected component. We really
6171 -- want it just as it appears above, and do not want the expander
6172 -- playing discriminal games etc with this reference. Then we append
6173 -- the argument to the list we are gathering.
6175 Set_Etype (Scomp, Etype (Real_Discr));
6176 Set_Analyzed (Scomp, True);
6177 Append_To (Args, Convert_To (Etype (Formal), Scomp));
6179 Next_Formal_With_Extras (Formal);
6180 Next_Discriminant (Discr);
6183 -- Now build and insert the call
6186 Make_Raise_Constraint_Error (Loc,
6188 Make_Function_Call (Loc,
6189 Name => New_Occurrence_Of (Discr_Fct, Loc),
6190 Parameter_Associations => Args),
6191 Reason => CE_Discriminant_Check_Failed));
6192 end Generate_Discriminant_Check;
6194 ---------------------------
6195 -- Generate_Index_Checks --
6196 ---------------------------
6198 procedure Generate_Index_Checks (N : Node_Id) is
6200 function Entity_Of_Prefix return Entity_Id;
6201 -- Returns the entity of the prefix of N (or Empty if not found)
6203 ----------------------
6204 -- Entity_Of_Prefix --
6205 ----------------------
6207 function Entity_Of_Prefix return Entity_Id is
6212 while not Is_Entity_Name (P) loop
6213 if not Nkind_In (P, N_Selected_Component,
6214 N_Indexed_Component)
6223 end Entity_Of_Prefix;
6227 Loc : constant Source_Ptr := Sloc (N);
6228 A : constant Node_Id := Prefix (N);
6229 A_Ent : constant Entity_Id := Entity_Of_Prefix;
6232 -- Start of processing for Generate_Index_Checks
6235 -- Ignore call if the prefix is not an array since we have a serious
6236 -- error in the sources. Ignore it also if index checks are suppressed
6237 -- for array object or type.
6239 if not Is_Array_Type (Etype (A))
6240 or else (Present (A_Ent) and then Index_Checks_Suppressed (A_Ent))
6241 or else Index_Checks_Suppressed (Etype (A))
6245 -- The indexed component we are dealing with contains 'Loop_Entry in its
6246 -- prefix. This case arises when analysis has determined that constructs
6249 -- Prefix'Loop_Entry (Expr)
6250 -- Prefix'Loop_Entry (Expr1, Expr2, ... ExprN)
6252 -- require rewriting for error detection purposes. A side effect of this
6253 -- action is the generation of index checks that mention 'Loop_Entry.
6254 -- Delay the generation of the check until 'Loop_Entry has been properly
6255 -- expanded. This is done in Expand_Loop_Entry_Attributes.
6257 elsif Nkind (Prefix (N)) = N_Attribute_Reference
6258 and then Attribute_Name (Prefix (N)) = Name_Loop_Entry
6263 -- Generate a raise of constraint error with the appropriate reason and
6264 -- a condition of the form:
6266 -- Base_Type (Sub) not in Array'Range (Subscript)
6268 -- Note that the reason we generate the conversion to the base type here
6269 -- is that we definitely want the range check to take place, even if it
6270 -- looks like the subtype is OK. Optimization considerations that allow
6271 -- us to omit the check have already been taken into account in the
6272 -- setting of the Do_Range_Check flag earlier on.
6274 Sub := First (Expressions (N));
6276 -- Handle string literals
6278 if Ekind (Etype (A)) = E_String_Literal_Subtype then
6279 if Do_Range_Check (Sub) then
6280 Set_Do_Range_Check (Sub, False);
6282 -- For string literals we obtain the bounds of the string from the
6283 -- associated subtype.
6286 Make_Raise_Constraint_Error (Loc,
6290 Convert_To (Base_Type (Etype (Sub)),
6291 Duplicate_Subexpr_Move_Checks (Sub)),
6293 Make_Attribute_Reference (Loc,
6294 Prefix => New_Occurrence_Of (Etype (A), Loc),
6295 Attribute_Name => Name_Range)),
6296 Reason => CE_Index_Check_Failed));
6303 A_Idx : Node_Id := Empty;
6310 A_Idx := First_Index (Etype (A));
6312 while Present (Sub) loop
6313 if Do_Range_Check (Sub) then
6314 Set_Do_Range_Check (Sub, False);
6316 -- Force evaluation except for the case of a simple name of
6317 -- a non-volatile entity.
6319 if not Is_Entity_Name (Sub)
6320 or else Treat_As_Volatile (Entity (Sub))
6322 Force_Evaluation (Sub);
6325 if Nkind (A_Idx) = N_Range then
6328 elsif Nkind (A_Idx) = N_Identifier
6329 or else Nkind (A_Idx) = N_Expanded_Name
6331 A_Range := Scalar_Range (Entity (A_Idx));
6333 else pragma Assert (Nkind (A_Idx) = N_Subtype_Indication);
6334 A_Range := Range_Expression (Constraint (A_Idx));
6337 -- For array objects with constant bounds we can generate
6338 -- the index check using the bounds of the type of the index
6341 and then Ekind (A_Ent) = E_Variable
6342 and then Is_Constant_Bound (Low_Bound (A_Range))
6343 and then Is_Constant_Bound (High_Bound (A_Range))
6346 Make_Attribute_Reference (Loc,
6348 New_Occurrence_Of (Etype (A_Idx), Loc),
6349 Attribute_Name => Name_Range);
6351 -- For arrays with non-constant bounds we cannot generate
6352 -- the index check using the bounds of the type of the index
6353 -- since it may reference discriminants of some enclosing
6354 -- type. We obtain the bounds directly from the prefix
6361 Num := New_List (Make_Integer_Literal (Loc, Ind));
6365 Make_Attribute_Reference (Loc,
6367 Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
6368 Attribute_Name => Name_Range,
6369 Expressions => Num);
6373 Make_Raise_Constraint_Error (Loc,
6377 Convert_To (Base_Type (Etype (Sub)),
6378 Duplicate_Subexpr_Move_Checks (Sub)),
6379 Right_Opnd => Range_N),
6380 Reason => CE_Index_Check_Failed));
6383 A_Idx := Next_Index (A_Idx);
6389 end Generate_Index_Checks;
6391 --------------------------
6392 -- Generate_Range_Check --
6393 --------------------------
6395 procedure Generate_Range_Check
6397 Target_Type : Entity_Id;
6398 Reason : RT_Exception_Code)
6400 Loc : constant Source_Ptr := Sloc (N);
6401 Source_Type : constant Entity_Id := Etype (N);
6402 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
6403 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
6405 procedure Convert_And_Check_Range;
6406 -- Convert the conversion operand to the target base type and save in
6407 -- a temporary. Then check the converted value against the range of the
6410 -----------------------------
6411 -- Convert_And_Check_Range --
6412 -----------------------------
6414 procedure Convert_And_Check_Range is
6415 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
6418 -- We make a temporary to hold the value of the converted value
6419 -- (converted to the base type), and then do the test against this
6420 -- temporary. The conversion itself is replaced by an occurrence of
6421 -- Tnn and followed by the explicit range check. Note that checks
6422 -- are suppressed for this code, since we don't want a recursive
6423 -- range check popping up.
6425 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
6426 -- [constraint_error when Tnn not in Target_Type]
6428 Insert_Actions (N, New_List (
6429 Make_Object_Declaration (Loc,
6430 Defining_Identifier => Tnn,
6431 Object_Definition => New_Occurrence_Of (Target_Base_Type, Loc),
6432 Constant_Present => True,
6434 Make_Type_Conversion (Loc,
6435 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
6436 Expression => Duplicate_Subexpr (N))),
6438 Make_Raise_Constraint_Error (Loc,
6441 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
6442 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
6444 Suppress => All_Checks);
6446 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
6448 -- Set the type of N, because the declaration for Tnn might not
6449 -- be analyzed yet, as is the case if N appears within a record
6450 -- declaration, as a discriminant constraint or expression.
6452 Set_Etype (N, Target_Base_Type);
6453 end Convert_And_Check_Range;
6455 -- Start of processing for Generate_Range_Check
6458 -- First special case, if the source type is already within the range
6459 -- of the target type, then no check is needed (probably we should have
6460 -- stopped Do_Range_Check from being set in the first place, but better
6461 -- late than never in preventing junk code and junk flag settings.
6463 if In_Subrange_Of (Source_Type, Target_Type)
6465 -- We do NOT apply this if the source node is a literal, since in this
6466 -- case the literal has already been labeled as having the subtype of
6470 (Nkind_In (N, N_Integer_Literal, N_Real_Literal, N_Character_Literal)
6473 and then Ekind (Entity (N)) = E_Enumeration_Literal))
6475 -- Also do not apply this for floating-point if Check_Float_Overflow
6478 (Is_Floating_Point_Type (Source_Type) and Check_Float_Overflow)
6480 Set_Do_Range_Check (N, False);
6484 -- Here a check is needed. If the expander is not active, or if we are
6485 -- in GNATProve mode, then simply set the Do_Range_Check flag and we
6486 -- are done. In both these cases, we just want to see the range check
6487 -- flag set, we do not want to generate the explicit range check code.
6489 if GNATprove_Mode or else not Expander_Active then
6490 Set_Do_Range_Check (N, True);
6494 -- Here we will generate an explicit range check, so we don't want to
6495 -- set the Do_Range check flag, since the range check is taken care of
6496 -- by the code we will generate.
6498 Set_Do_Range_Check (N, False);
6500 -- Force evaluation of the node, so that it does not get evaluated twice
6501 -- (once for the check, once for the actual reference). Such a double
6502 -- evaluation is always a potential source of inefficiency, and is
6503 -- functionally incorrect in the volatile case.
6505 if not Is_Entity_Name (N) or else Treat_As_Volatile (Entity (N)) then
6506 Force_Evaluation (N);
6509 -- The easiest case is when Source_Base_Type and Target_Base_Type are
6510 -- the same since in this case we can simply do a direct check of the
6511 -- value of N against the bounds of Target_Type.
6513 -- [constraint_error when N not in Target_Type]
6515 -- Note: this is by far the most common case, for example all cases of
6516 -- checks on the RHS of assignments are in this category, but not all
6517 -- cases are like this. Notably conversions can involve two types.
6519 if Source_Base_Type = Target_Base_Type then
6521 -- Insert the explicit range check. Note that we suppress checks for
6522 -- this code, since we don't want a recursive range check popping up.
6525 Make_Raise_Constraint_Error (Loc,
6528 Left_Opnd => Duplicate_Subexpr (N),
6529 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
6531 Suppress => All_Checks);
6533 -- Next test for the case where the target type is within the bounds
6534 -- of the base type of the source type, since in this case we can
6535 -- simply convert these bounds to the base type of T to do the test.
6537 -- [constraint_error when N not in
6538 -- Source_Base_Type (Target_Type'First)
6540 -- Source_Base_Type(Target_Type'Last))]
6542 -- The conversions will always work and need no check
6544 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
6545 -- of converting from an enumeration value to an integer type, such as
6546 -- occurs for the case of generating a range check on Enum'Val(Exp)
6547 -- (which used to be handled by gigi). This is OK, since the conversion
6548 -- itself does not require a check.
6550 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
6552 -- Insert the explicit range check. Note that we suppress checks for
6553 -- this code, since we don't want a recursive range check popping up.
6555 if Is_Discrete_Type (Source_Base_Type)
6557 Is_Discrete_Type (Target_Base_Type)
6560 Make_Raise_Constraint_Error (Loc,
6563 Left_Opnd => Duplicate_Subexpr (N),
6568 Unchecked_Convert_To (Source_Base_Type,
6569 Make_Attribute_Reference (Loc,
6571 New_Occurrence_Of (Target_Type, Loc),
6572 Attribute_Name => Name_First)),
6575 Unchecked_Convert_To (Source_Base_Type,
6576 Make_Attribute_Reference (Loc,
6578 New_Occurrence_Of (Target_Type, Loc),
6579 Attribute_Name => Name_Last)))),
6581 Suppress => All_Checks);
6583 -- For conversions involving at least one type that is not discrete,
6584 -- first convert to target type and then generate the range check.
6585 -- This avoids problems with values that are close to a bound of the
6586 -- target type that would fail a range check when done in a larger
6587 -- source type before converting but would pass if converted with
6588 -- rounding and then checked (such as in float-to-float conversions).
6591 Convert_And_Check_Range;
6594 -- Note that at this stage we now that the Target_Base_Type is not in
6595 -- the range of the Source_Base_Type (since even the Target_Type itself
6596 -- is not in this range). It could still be the case that Source_Type is
6597 -- in range of the target base type since we have not checked that case.
6599 -- If that is the case, we can freely convert the source to the target,
6600 -- and then test the target result against the bounds.
6602 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
6603 Convert_And_Check_Range;
6605 -- At this stage, we know that we have two scalar types, which are
6606 -- directly convertible, and where neither scalar type has a base
6607 -- range that is in the range of the other scalar type.
6609 -- The only way this can happen is with a signed and unsigned type.
6610 -- So test for these two cases:
6613 -- Case of the source is unsigned and the target is signed
6615 if Is_Unsigned_Type (Source_Base_Type)
6616 and then not Is_Unsigned_Type (Target_Base_Type)
6618 -- If the source is unsigned and the target is signed, then we
6619 -- know that the source is not shorter than the target (otherwise
6620 -- the source base type would be in the target base type range).
6622 -- In other words, the unsigned type is either the same size as
6623 -- the target, or it is larger. It cannot be smaller.
6626 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
6628 -- We only need to check the low bound if the low bound of the
6629 -- target type is non-negative. If the low bound of the target
6630 -- type is negative, then we know that we will fit fine.
6632 -- If the high bound of the target type is negative, then we
6633 -- know we have a constraint error, since we can't possibly
6634 -- have a negative source.
6636 -- With these two checks out of the way, we can do the check
6637 -- using the source type safely
6639 -- This is definitely the most annoying case.
6641 -- [constraint_error
6642 -- when (Target_Type'First >= 0
6644 -- N < Source_Base_Type (Target_Type'First))
6645 -- or else Target_Type'Last < 0
6646 -- or else N > Source_Base_Type (Target_Type'Last)];
6648 -- We turn off all checks since we know that the conversions
6649 -- will work fine, given the guards for negative values.
6652 Make_Raise_Constraint_Error (Loc,
6658 Left_Opnd => Make_Op_Ge (Loc,
6660 Make_Attribute_Reference (Loc,
6662 New_Occurrence_Of (Target_Type, Loc),
6663 Attribute_Name => Name_First),
6664 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
6668 Left_Opnd => Duplicate_Subexpr (N),
6670 Convert_To (Source_Base_Type,
6671 Make_Attribute_Reference (Loc,
6673 New_Occurrence_Of (Target_Type, Loc),
6674 Attribute_Name => Name_First)))),
6679 Make_Attribute_Reference (Loc,
6680 Prefix => New_Occurrence_Of (Target_Type, Loc),
6681 Attribute_Name => Name_Last),
6682 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
6686 Left_Opnd => Duplicate_Subexpr (N),
6688 Convert_To (Source_Base_Type,
6689 Make_Attribute_Reference (Loc,
6690 Prefix => New_Occurrence_Of (Target_Type, Loc),
6691 Attribute_Name => Name_Last)))),
6694 Suppress => All_Checks);
6696 -- Only remaining possibility is that the source is signed and
6697 -- the target is unsigned.
6700 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
6701 and then Is_Unsigned_Type (Target_Base_Type));
6703 -- If the source is signed and the target is unsigned, then we
6704 -- know that the target is not shorter than the source (otherwise
6705 -- the target base type would be in the source base type range).
6707 -- In other words, the unsigned type is either the same size as
6708 -- the target, or it is larger. It cannot be smaller.
6710 -- Clearly we have an error if the source value is negative since
6711 -- no unsigned type can have negative values. If the source type
6712 -- is non-negative, then the check can be done using the target
6715 -- Tnn : constant Target_Base_Type (N) := Target_Type;
6717 -- [constraint_error
6718 -- when N < 0 or else Tnn not in Target_Type];
6720 -- We turn off all checks for the conversion of N to the target
6721 -- base type, since we generate the explicit check to ensure that
6722 -- the value is non-negative
6725 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
6728 Insert_Actions (N, New_List (
6729 Make_Object_Declaration (Loc,
6730 Defining_Identifier => Tnn,
6731 Object_Definition =>
6732 New_Occurrence_Of (Target_Base_Type, Loc),
6733 Constant_Present => True,
6735 Make_Unchecked_Type_Conversion (Loc,
6737 New_Occurrence_Of (Target_Base_Type, Loc),
6738 Expression => Duplicate_Subexpr (N))),
6740 Make_Raise_Constraint_Error (Loc,
6745 Left_Opnd => Duplicate_Subexpr (N),
6746 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
6750 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
6752 New_Occurrence_Of (Target_Type, Loc))),
6755 Suppress => All_Checks);
6757 -- Set the Etype explicitly, because Insert_Actions may have
6758 -- placed the declaration in the freeze list for an enclosing
6759 -- construct, and thus it is not analyzed yet.
6761 Set_Etype (Tnn, Target_Base_Type);
6762 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
6766 end Generate_Range_Check;
6772 function Get_Check_Id (N : Name_Id) return Check_Id is
6774 -- For standard check name, we can do a direct computation
6776 if N in First_Check_Name .. Last_Check_Name then
6777 return Check_Id (N - (First_Check_Name - 1));
6779 -- For non-standard names added by pragma Check_Name, search table
6782 for J in All_Checks + 1 .. Check_Names.Last loop
6783 if Check_Names.Table (J) = N then
6789 -- No matching name found
6794 ---------------------
6795 -- Get_Discriminal --
6796 ---------------------
6798 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
6799 Loc : constant Source_Ptr := Sloc (E);
6804 -- The bound can be a bona fide parameter of a protected operation,
6805 -- rather than a prival encoded as an in-parameter.
6807 if No (Discriminal_Link (Entity (Bound))) then
6811 -- Climb the scope stack looking for an enclosing protected type. If
6812 -- we run out of scopes, return the bound itself.
6815 while Present (Sc) loop
6816 if Sc = Standard_Standard then
6818 elsif Ekind (Sc) = E_Protected_Type then
6825 D := First_Discriminant (Sc);
6826 while Present (D) loop
6827 if Chars (D) = Chars (Bound) then
6828 return New_Occurrence_Of (Discriminal (D), Loc);
6831 Next_Discriminant (D);
6835 end Get_Discriminal;
6837 ----------------------
6838 -- Get_Range_Checks --
6839 ----------------------
6841 function Get_Range_Checks
6843 Target_Typ : Entity_Id;
6844 Source_Typ : Entity_Id := Empty;
6845 Warn_Node : Node_Id := Empty) return Check_Result
6849 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
6850 end Get_Range_Checks;
6856 function Guard_Access
6859 Ck_Node : Node_Id) return Node_Id
6862 if Nkind (Cond) = N_Or_Else then
6863 Set_Paren_Count (Cond, 1);
6866 if Nkind (Ck_Node) = N_Allocator then
6874 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
6875 Right_Opnd => Make_Null (Loc)),
6876 Right_Opnd => Cond);
6880 -----------------------------
6881 -- Index_Checks_Suppressed --
6882 -----------------------------
6884 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
6886 if Present (E) and then Checks_May_Be_Suppressed (E) then
6887 return Is_Check_Suppressed (E, Index_Check);
6889 return Scope_Suppress.Suppress (Index_Check);
6891 end Index_Checks_Suppressed;
6897 procedure Initialize is
6899 for J in Determine_Range_Cache_N'Range loop
6900 Determine_Range_Cache_N (J) := Empty;
6905 for J in Int range 1 .. All_Checks loop
6906 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
6910 -------------------------
6911 -- Insert_Range_Checks --
6912 -------------------------
6914 procedure Insert_Range_Checks
6915 (Checks : Check_Result;
6917 Suppress_Typ : Entity_Id;
6918 Static_Sloc : Source_Ptr := No_Location;
6919 Flag_Node : Node_Id := Empty;
6920 Do_Before : Boolean := False)
6922 Internal_Flag_Node : Node_Id := Flag_Node;
6923 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
6925 Check_Node : Node_Id;
6926 Checks_On : constant Boolean :=
6927 (not Index_Checks_Suppressed (Suppress_Typ))
6928 or else (not Range_Checks_Suppressed (Suppress_Typ));
6931 -- For now we just return if Checks_On is false, however this should be
6932 -- enhanced to check for an always True value in the condition and to
6933 -- generate a compilation warning???
6935 if not Expander_Active or not Checks_On then
6939 if Static_Sloc = No_Location then
6940 Internal_Static_Sloc := Sloc (Node);
6943 if No (Flag_Node) then
6944 Internal_Flag_Node := Node;
6947 for J in 1 .. 2 loop
6948 exit when No (Checks (J));
6950 if Nkind (Checks (J)) = N_Raise_Constraint_Error
6951 and then Present (Condition (Checks (J)))
6953 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
6954 Check_Node := Checks (J);
6955 Mark_Rewrite_Insertion (Check_Node);
6958 Insert_Before_And_Analyze (Node, Check_Node);
6960 Insert_After_And_Analyze (Node, Check_Node);
6963 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
6968 Make_Raise_Constraint_Error (Internal_Static_Sloc,
6969 Reason => CE_Range_Check_Failed);
6970 Mark_Rewrite_Insertion (Check_Node);
6973 Insert_Before_And_Analyze (Node, Check_Node);
6975 Insert_After_And_Analyze (Node, Check_Node);
6979 end Insert_Range_Checks;
6981 ------------------------
6982 -- Insert_Valid_Check --
6983 ------------------------
6985 procedure Insert_Valid_Check (Expr : Node_Id) is
6986 Loc : constant Source_Ptr := Sloc (Expr);
6987 Typ : constant Entity_Id := Etype (Expr);
6991 -- Do not insert if checks off, or if not checking validity or
6992 -- if expression is known to be valid
6994 if not Validity_Checks_On
6995 or else Range_Or_Validity_Checks_Suppressed (Expr)
6996 or else Expr_Known_Valid (Expr)
7001 -- Do not insert checks within a predicate function. This will arise
7002 -- if the current unit and the predicate function are being compiled
7003 -- with validity checks enabled.
7005 if Present (Predicate_Function (Typ))
7006 and then Current_Scope = Predicate_Function (Typ)
7011 -- If the expression is a packed component of a modular type of the
7012 -- right size, the data is always valid.
7014 if Nkind (Expr) = N_Selected_Component
7015 and then Present (Component_Clause (Entity (Selector_Name (Expr))))
7016 and then Is_Modular_Integer_Type (Typ)
7017 and then Modulus (Typ) = 2 ** Esize (Entity (Selector_Name (Expr)))
7022 -- If we have a checked conversion, then validity check applies to
7023 -- the expression inside the conversion, not the result, since if
7024 -- the expression inside is valid, then so is the conversion result.
7027 while Nkind (Exp) = N_Type_Conversion loop
7028 Exp := Expression (Exp);
7031 -- We are about to insert the validity check for Exp. We save and
7032 -- reset the Do_Range_Check flag over this validity check, and then
7033 -- put it back for the final original reference (Exp may be rewritten).
7036 DRC : constant Boolean := Do_Range_Check (Exp);
7041 Set_Do_Range_Check (Exp, False);
7043 -- Force evaluation to avoid multiple reads for atomic/volatile
7045 -- Note: we set Name_Req to False. We used to set it to True, with
7046 -- the thinking that a name is required as the prefix of the 'Valid
7047 -- call, but in fact the check that the prefix of an attribute is
7048 -- a name is in the parser, and we just don't require it here.
7049 -- Moreover, when we set Name_Req to True, that interfered with the
7050 -- checking for Volatile, since we couldn't just capture the value.
7052 if Is_Entity_Name (Exp)
7053 and then Is_Volatile (Entity (Exp))
7055 -- Same reasoning as above for setting Name_Req to False
7057 Force_Evaluation (Exp, Name_Req => False);
7060 -- Build the prefix for the 'Valid call
7062 PV := Duplicate_Subexpr_No_Checks (Exp, Name_Req => False);
7064 -- A rather specialized test. If PV is an analyzed expression which
7065 -- is an indexed component of a packed array that has not been
7066 -- properly expanded, turn off its Analyzed flag to make sure it
7067 -- gets properly reexpanded. If the prefix is an access value,
7068 -- the dereference will be added later.
7070 -- The reason this arises is that Duplicate_Subexpr_No_Checks did
7071 -- an analyze with the old parent pointer. This may point e.g. to
7072 -- a subprogram call, which deactivates this expansion.
7075 and then Nkind (PV) = N_Indexed_Component
7076 and then Is_Array_Type (Etype (Prefix (PV)))
7077 and then Present (Packed_Array_Impl_Type (Etype (Prefix (PV))))
7079 Set_Analyzed (PV, False);
7082 -- Build the raise CE node to check for validity. We build a type
7083 -- qualification for the prefix, since it may not be of the form of
7084 -- a name, and we don't care in this context!
7087 Make_Raise_Constraint_Error (Loc,
7091 Make_Attribute_Reference (Loc,
7093 Attribute_Name => Name_Valid)),
7094 Reason => CE_Invalid_Data);
7096 -- Insert the validity check. Note that we do this with validity
7097 -- checks turned off, to avoid recursion, we do not want validity
7098 -- checks on the validity checking code itself.
7100 Insert_Action (Expr, CE, Suppress => Validity_Check);
7102 -- If the expression is a reference to an element of a bit-packed
7103 -- array, then it is rewritten as a renaming declaration. If the
7104 -- expression is an actual in a call, it has not been expanded,
7105 -- waiting for the proper point at which to do it. The same happens
7106 -- with renamings, so that we have to force the expansion now. This
7107 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
7110 if Is_Entity_Name (Exp)
7111 and then Nkind (Parent (Entity (Exp))) =
7112 N_Object_Renaming_Declaration
7115 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
7117 if Nkind (Old_Exp) = N_Indexed_Component
7118 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
7120 Expand_Packed_Element_Reference (Old_Exp);
7125 -- Put back the Do_Range_Check flag on the resulting (possibly
7126 -- rewritten) expression.
7128 -- Note: it might be thought that a validity check is not required
7129 -- when a range check is present, but that's not the case, because
7130 -- the back end is allowed to assume for the range check that the
7131 -- operand is within its declared range (an assumption that validity
7132 -- checking is all about NOT assuming).
7134 -- Note: no need to worry about Possible_Local_Raise here, it will
7135 -- already have been called if original node has Do_Range_Check set.
7137 Set_Do_Range_Check (Exp, DRC);
7139 end Insert_Valid_Check;
7141 -------------------------------------
7142 -- Is_Signed_Integer_Arithmetic_Op --
7143 -------------------------------------
7145 function Is_Signed_Integer_Arithmetic_Op (N : Node_Id) return Boolean is
7148 when N_Op_Abs | N_Op_Add | N_Op_Divide | N_Op_Expon |
7149 N_Op_Minus | N_Op_Mod | N_Op_Multiply | N_Op_Plus |
7150 N_Op_Rem | N_Op_Subtract =>
7151 return Is_Signed_Integer_Type (Etype (N));
7153 when N_If_Expression | N_Case_Expression =>
7154 return Is_Signed_Integer_Type (Etype (N));
7159 end Is_Signed_Integer_Arithmetic_Op;
7161 ----------------------------------
7162 -- Install_Null_Excluding_Check --
7163 ----------------------------------
7165 procedure Install_Null_Excluding_Check (N : Node_Id) is
7166 Loc : constant Source_Ptr := Sloc (Parent (N));
7167 Typ : constant Entity_Id := Etype (N);
7169 function Safe_To_Capture_In_Parameter_Value return Boolean;
7170 -- Determines if it is safe to capture Known_Non_Null status for an
7171 -- the entity referenced by node N. The caller ensures that N is indeed
7172 -- an entity name. It is safe to capture the non-null status for an IN
7173 -- parameter when the reference occurs within a declaration that is sure
7174 -- to be executed as part of the declarative region.
7176 procedure Mark_Non_Null;
7177 -- After installation of check, if the node in question is an entity
7178 -- name, then mark this entity as non-null if possible.
7180 function Safe_To_Capture_In_Parameter_Value return Boolean is
7181 E : constant Entity_Id := Entity (N);
7182 S : constant Entity_Id := Current_Scope;
7186 if Ekind (E) /= E_In_Parameter then
7190 -- Two initial context checks. We must be inside a subprogram body
7191 -- with declarations and reference must not appear in nested scopes.
7193 if (Ekind (S) /= E_Function and then Ekind (S) /= E_Procedure)
7194 or else Scope (E) /= S
7199 S_Par := Parent (Parent (S));
7201 if Nkind (S_Par) /= N_Subprogram_Body
7202 or else No (Declarations (S_Par))
7212 -- Retrieve the declaration node of N (if any). Note that N
7213 -- may be a part of a complex initialization expression.
7217 while Present (P) loop
7219 -- If we have a short circuit form, and we are within the right
7220 -- hand expression, we return false, since the right hand side
7221 -- is not guaranteed to be elaborated.
7223 if Nkind (P) in N_Short_Circuit
7224 and then N = Right_Opnd (P)
7229 -- Similarly, if we are in an if expression and not part of the
7230 -- condition, then we return False, since neither the THEN or
7231 -- ELSE dependent expressions will always be elaborated.
7233 if Nkind (P) = N_If_Expression
7234 and then N /= First (Expressions (P))
7239 -- If within a case expression, and not part of the expression,
7240 -- then return False, since a particular dependent expression
7241 -- may not always be elaborated
7243 if Nkind (P) = N_Case_Expression
7244 and then N /= Expression (P)
7249 -- While traversing the parent chain, if node N belongs to a
7250 -- statement, then it may never appear in a declarative region.
7252 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
7253 or else Nkind (P) = N_Procedure_Call_Statement
7258 -- If we are at a declaration, record it and exit
7260 if Nkind (P) in N_Declaration
7261 and then Nkind (P) not in N_Subprogram_Specification
7274 return List_Containing (N_Decl) = Declarations (S_Par);
7276 end Safe_To_Capture_In_Parameter_Value;
7282 procedure Mark_Non_Null is
7284 -- Only case of interest is if node N is an entity name
7286 if Is_Entity_Name (N) then
7288 -- For sure, we want to clear an indication that this is known to
7289 -- be null, since if we get past this check, it definitely is not.
7291 Set_Is_Known_Null (Entity (N), False);
7293 -- We can mark the entity as known to be non-null if either it is
7294 -- safe to capture the value, or in the case of an IN parameter,
7295 -- which is a constant, if the check we just installed is in the
7296 -- declarative region of the subprogram body. In this latter case,
7297 -- a check is decisive for the rest of the body if the expression
7298 -- is sure to be elaborated, since we know we have to elaborate
7299 -- all declarations before executing the body.
7301 -- Couldn't this always be part of Safe_To_Capture_Value ???
7303 if Safe_To_Capture_Value (N, Entity (N))
7304 or else Safe_To_Capture_In_Parameter_Value
7306 Set_Is_Known_Non_Null (Entity (N));
7311 -- Start of processing for Install_Null_Excluding_Check
7314 pragma Assert (Is_Access_Type (Typ));
7316 -- No check inside a generic, check will be emitted in instance
7318 if Inside_A_Generic then
7322 -- No check needed if known to be non-null
7324 if Known_Non_Null (N) then
7328 -- If known to be null, here is where we generate a compile time check
7330 if Known_Null (N) then
7332 -- Avoid generating warning message inside init procs. In SPARK mode
7333 -- we can go ahead and call Apply_Compile_Time_Constraint_Error
7334 -- since it will be turned into an error in any case.
7336 if (not Inside_Init_Proc or else SPARK_Mode = On)
7338 -- Do not emit the warning within a conditional expression,
7339 -- where the expression might not be evaluated, and the warning
7340 -- appear as extraneous noise.
7342 and then not Within_Case_Or_If_Expression (N)
7344 Apply_Compile_Time_Constraint_Error
7345 (N, "null value not allowed here??", CE_Access_Check_Failed);
7347 -- Remaining cases, where we silently insert the raise
7351 Make_Raise_Constraint_Error (Loc,
7352 Reason => CE_Access_Check_Failed));
7359 -- If entity is never assigned, for sure a warning is appropriate
7361 if Is_Entity_Name (N) then
7362 Check_Unset_Reference (N);
7365 -- No check needed if checks are suppressed on the range. Note that we
7366 -- don't set Is_Known_Non_Null in this case (we could legitimately do
7367 -- so, since the program is erroneous, but we don't like to casually
7368 -- propagate such conclusions from erroneosity).
7370 if Access_Checks_Suppressed (Typ) then
7374 -- No check needed for access to concurrent record types generated by
7375 -- the expander. This is not just an optimization (though it does indeed
7376 -- remove junk checks). It also avoids generation of junk warnings.
7378 if Nkind (N) in N_Has_Chars
7379 and then Chars (N) = Name_uObject
7380 and then Is_Concurrent_Record_Type
7381 (Directly_Designated_Type (Etype (N)))
7386 -- No check needed in interface thunks since the runtime check is
7387 -- already performed at the caller side.
7389 if Is_Thunk (Current_Scope) then
7393 -- No check needed for the Get_Current_Excep.all.all idiom generated by
7394 -- the expander within exception handlers, since we know that the value
7395 -- can never be null.
7397 -- Is this really the right way to do this? Normally we generate such
7398 -- code in the expander with checks off, and that's how we suppress this
7399 -- kind of junk check ???
7401 if Nkind (N) = N_Function_Call
7402 and then Nkind (Name (N)) = N_Explicit_Dereference
7403 and then Nkind (Prefix (Name (N))) = N_Identifier
7404 and then Is_RTE (Entity (Prefix (Name (N))), RE_Get_Current_Excep)
7409 -- Otherwise install access check
7412 Make_Raise_Constraint_Error (Loc,
7415 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
7416 Right_Opnd => Make_Null (Loc)),
7417 Reason => CE_Access_Check_Failed));
7420 end Install_Null_Excluding_Check;
7422 --------------------------
7423 -- Install_Static_Check --
7424 --------------------------
7426 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
7427 Stat : constant Boolean := Is_OK_Static_Expression (R_Cno);
7428 Typ : constant Entity_Id := Etype (R_Cno);
7432 Make_Raise_Constraint_Error (Loc,
7433 Reason => CE_Range_Check_Failed));
7434 Set_Analyzed (R_Cno);
7435 Set_Etype (R_Cno, Typ);
7436 Set_Raises_Constraint_Error (R_Cno);
7437 Set_Is_Static_Expression (R_Cno, Stat);
7439 -- Now deal with possible local raise handling
7441 Possible_Local_Raise (R_Cno, Standard_Constraint_Error);
7442 end Install_Static_Check;
7444 -------------------------
7445 -- Is_Check_Suppressed --
7446 -------------------------
7448 function Is_Check_Suppressed (E : Entity_Id; C : Check_Id) return Boolean is
7449 Ptr : Suppress_Stack_Entry_Ptr;
7452 -- First search the local entity suppress stack. We search this from the
7453 -- top of the stack down so that we get the innermost entry that applies
7454 -- to this case if there are nested entries.
7456 Ptr := Local_Suppress_Stack_Top;
7457 while Ptr /= null loop
7458 if (Ptr.Entity = Empty or else Ptr.Entity = E)
7459 and then (Ptr.Check = All_Checks or else Ptr.Check = C)
7461 return Ptr.Suppress;
7467 -- Now search the global entity suppress table for a matching entry.
7468 -- We also search this from the top down so that if there are multiple
7469 -- pragmas for the same entity, the last one applies (not clear what
7470 -- or whether the RM specifies this handling, but it seems reasonable).
7472 Ptr := Global_Suppress_Stack_Top;
7473 while Ptr /= null loop
7474 if (Ptr.Entity = Empty or else Ptr.Entity = E)
7475 and then (Ptr.Check = All_Checks or else Ptr.Check = C)
7477 return Ptr.Suppress;
7483 -- If we did not find a matching entry, then use the normal scope
7484 -- suppress value after all (actually this will be the global setting
7485 -- since it clearly was not overridden at any point). For a predefined
7486 -- check, we test the specific flag. For a user defined check, we check
7487 -- the All_Checks flag. The Overflow flag requires special handling to
7488 -- deal with the General vs Assertion case
7490 if C = Overflow_Check then
7491 return Overflow_Checks_Suppressed (Empty);
7492 elsif C in Predefined_Check_Id then
7493 return Scope_Suppress.Suppress (C);
7495 return Scope_Suppress.Suppress (All_Checks);
7497 end Is_Check_Suppressed;
7499 ---------------------
7500 -- Kill_All_Checks --
7501 ---------------------
7503 procedure Kill_All_Checks is
7505 if Debug_Flag_CC then
7506 w ("Kill_All_Checks");
7509 -- We reset the number of saved checks to zero, and also modify all
7510 -- stack entries for statement ranges to indicate that the number of
7511 -- checks at each level is now zero.
7513 Num_Saved_Checks := 0;
7515 -- Note: the Int'Min here avoids any possibility of J being out of
7516 -- range when called from e.g. Conditional_Statements_Begin.
7518 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
7519 Saved_Checks_Stack (J) := 0;
7521 end Kill_All_Checks;
7527 procedure Kill_Checks (V : Entity_Id) is
7529 if Debug_Flag_CC then
7530 w ("Kill_Checks for entity", Int (V));
7533 for J in 1 .. Num_Saved_Checks loop
7534 if Saved_Checks (J).Entity = V then
7535 if Debug_Flag_CC then
7536 w (" Checks killed for saved check ", J);
7539 Saved_Checks (J).Killed := True;
7544 ------------------------------
7545 -- Length_Checks_Suppressed --
7546 ------------------------------
7548 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
7550 if Present (E) and then Checks_May_Be_Suppressed (E) then
7551 return Is_Check_Suppressed (E, Length_Check);
7553 return Scope_Suppress.Suppress (Length_Check);
7555 end Length_Checks_Suppressed;
7557 -----------------------
7558 -- Make_Bignum_Block --
7559 -----------------------
7561 function Make_Bignum_Block (Loc : Source_Ptr) return Node_Id is
7562 M : constant Entity_Id := Make_Defining_Identifier (Loc, Name_uM);
7565 Make_Block_Statement (Loc,
7567 New_List (Build_SS_Mark_Call (Loc, M)),
7568 Handled_Statement_Sequence =>
7569 Make_Handled_Sequence_Of_Statements (Loc,
7570 Statements => New_List (Build_SS_Release_Call (Loc, M))));
7571 end Make_Bignum_Block;
7573 ----------------------------------
7574 -- Minimize_Eliminate_Overflows --
7575 ----------------------------------
7577 -- This is a recursive routine that is called at the top of an expression
7578 -- tree to properly process overflow checking for a whole subtree by making
7579 -- recursive calls to process operands. This processing may involve the use
7580 -- of bignum or long long integer arithmetic, which will change the types
7581 -- of operands and results. That's why we can't do this bottom up (since
7582 -- it would interfere with semantic analysis).
7584 -- What happens is that if MINIMIZED/ELIMINATED mode is in effect then
7585 -- the operator expansion routines, as well as the expansion routines for
7586 -- if/case expression, do nothing (for the moment) except call the routine
7587 -- to apply the overflow check (Apply_Arithmetic_Overflow_Check). That
7588 -- routine does nothing for non top-level nodes, so at the point where the
7589 -- call is made for the top level node, the entire expression subtree has
7590 -- not been expanded, or processed for overflow. All that has to happen as
7591 -- a result of the top level call to this routine.
7593 -- As noted above, the overflow processing works by making recursive calls
7594 -- for the operands, and figuring out what to do, based on the processing
7595 -- of these operands (e.g. if a bignum operand appears, the parent op has
7596 -- to be done in bignum mode), and the determined ranges of the operands.
7598 -- After possible rewriting of a constituent subexpression node, a call is
7599 -- made to either reexpand the node (if nothing has changed) or reanalyze
7600 -- the node (if it has been modified by the overflow check processing). The
7601 -- Analyzed_Flag is set to False before the reexpand/reanalyze. To avoid
7602 -- a recursive call into the whole overflow apparatus, an important rule
7603 -- for this call is that the overflow handling mode must be temporarily set
7606 procedure Minimize_Eliminate_Overflows
7610 Top_Level : Boolean)
7612 Rtyp : constant Entity_Id := Etype (N);
7613 pragma Assert (Is_Signed_Integer_Type (Rtyp));
7614 -- Result type, must be a signed integer type
7616 Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
7617 pragma Assert (Check_Mode in Minimized_Or_Eliminated);
7619 Loc : constant Source_Ptr := Sloc (N);
7622 -- Ranges of values for right operand (operator case)
7625 -- Ranges of values for left operand (operator case)
7627 LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer);
7628 -- Operands and results are of this type when we convert
7630 LLLo : constant Uint := Intval (Type_Low_Bound (LLIB));
7631 LLHi : constant Uint := Intval (Type_High_Bound (LLIB));
7632 -- Bounds of Long_Long_Integer
7634 Binary : constant Boolean := Nkind (N) in N_Binary_Op;
7635 -- Indicates binary operator case
7638 -- Used in call to Determine_Range
7640 Bignum_Operands : Boolean;
7641 -- Set True if one or more operands is already of type Bignum, meaning
7642 -- that for sure (regardless of Top_Level setting) we are committed to
7643 -- doing the operation in Bignum mode (or in the case of a case or if
7644 -- expression, converting all the dependent expressions to Bignum).
7646 Long_Long_Integer_Operands : Boolean;
7647 -- Set True if one or more operands is already of type Long_Long_Integer
7648 -- which means that if the result is known to be in the result type
7649 -- range, then we must convert such operands back to the result type.
7651 procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False);
7652 -- This is called when we have modified the node and we therefore need
7653 -- to reanalyze it. It is important that we reset the mode to STRICT for
7654 -- this reanalysis, since if we leave it in MINIMIZED or ELIMINATED mode
7655 -- we would reenter this routine recursively which would not be good.
7656 -- The argument Suppress is set True if we also want to suppress
7657 -- overflow checking for the reexpansion (this is set when we know
7658 -- overflow is not possible). Typ is the type for the reanalysis.
7660 procedure Reexpand (Suppress : Boolean := False);
7661 -- This is like Reanalyze, but does not do the Analyze step, it only
7662 -- does a reexpansion. We do this reexpansion in STRICT mode, so that
7663 -- instead of reentering the MINIMIZED/ELIMINATED mode processing, we
7664 -- follow the normal expansion path (e.g. converting A**4 to A**2**2).
7665 -- Note that skipping reanalysis is not just an optimization, testing
7666 -- has showed up several complex cases in which reanalyzing an already
7667 -- analyzed node causes incorrect behavior.
7669 function In_Result_Range return Boolean;
7670 -- Returns True iff Lo .. Hi are within range of the result type
7672 procedure Max (A : in out Uint; B : Uint);
7673 -- If A is No_Uint, sets A to B, else to UI_Max (A, B)
7675 procedure Min (A : in out Uint; B : Uint);
7676 -- If A is No_Uint, sets A to B, else to UI_Min (A, B)
7678 ---------------------
7679 -- In_Result_Range --
7680 ---------------------
7682 function In_Result_Range return Boolean is
7684 if Lo = No_Uint or else Hi = No_Uint then
7687 elsif Is_OK_Static_Subtype (Etype (N)) then
7688 return Lo >= Expr_Value (Type_Low_Bound (Rtyp))
7690 Hi <= Expr_Value (Type_High_Bound (Rtyp));
7693 return Lo >= Expr_Value (Type_Low_Bound (Base_Type (Rtyp)))
7695 Hi <= Expr_Value (Type_High_Bound (Base_Type (Rtyp)));
7697 end In_Result_Range;
7703 procedure Max (A : in out Uint; B : Uint) is
7705 if A = No_Uint or else B > A then
7714 procedure Min (A : in out Uint; B : Uint) is
7716 if A = No_Uint or else B < A then
7725 procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False) is
7726 Svg : constant Overflow_Mode_Type :=
7727 Scope_Suppress.Overflow_Mode_General;
7728 Sva : constant Overflow_Mode_Type :=
7729 Scope_Suppress.Overflow_Mode_Assertions;
7730 Svo : constant Boolean :=
7731 Scope_Suppress.Suppress (Overflow_Check);
7734 Scope_Suppress.Overflow_Mode_General := Strict;
7735 Scope_Suppress.Overflow_Mode_Assertions := Strict;
7738 Scope_Suppress.Suppress (Overflow_Check) := True;
7741 Analyze_And_Resolve (N, Typ);
7743 Scope_Suppress.Suppress (Overflow_Check) := Svo;
7744 Scope_Suppress.Overflow_Mode_General := Svg;
7745 Scope_Suppress.Overflow_Mode_Assertions := Sva;
7752 procedure Reexpand (Suppress : Boolean := False) is
7753 Svg : constant Overflow_Mode_Type :=
7754 Scope_Suppress.Overflow_Mode_General;
7755 Sva : constant Overflow_Mode_Type :=
7756 Scope_Suppress.Overflow_Mode_Assertions;
7757 Svo : constant Boolean :=
7758 Scope_Suppress.Suppress (Overflow_Check);
7761 Scope_Suppress.Overflow_Mode_General := Strict;
7762 Scope_Suppress.Overflow_Mode_Assertions := Strict;
7763 Set_Analyzed (N, False);
7766 Scope_Suppress.Suppress (Overflow_Check) := True;
7771 Scope_Suppress.Suppress (Overflow_Check) := Svo;
7772 Scope_Suppress.Overflow_Mode_General := Svg;
7773 Scope_Suppress.Overflow_Mode_Assertions := Sva;
7776 -- Start of processing for Minimize_Eliminate_Overflows
7779 -- Case where we do not have a signed integer arithmetic operation
7781 if not Is_Signed_Integer_Arithmetic_Op (N) then
7783 -- Use the normal Determine_Range routine to get the range. We
7784 -- don't require operands to be valid, invalid values may result in
7785 -- rubbish results where the result has not been properly checked for
7786 -- overflow, that's fine.
7788 Determine_Range (N, OK, Lo, Hi, Assume_Valid => False);
7790 -- If Determine_Range did not work (can this in fact happen? Not
7791 -- clear but might as well protect), use type bounds.
7794 Lo := Intval (Type_Low_Bound (Base_Type (Etype (N))));
7795 Hi := Intval (Type_High_Bound (Base_Type (Etype (N))));
7798 -- If we don't have a binary operator, all we have to do is to set
7799 -- the Hi/Lo range, so we are done.
7803 -- Processing for if expression
7805 elsif Nkind (N) = N_If_Expression then
7807 Then_DE : constant Node_Id := Next (First (Expressions (N)));
7808 Else_DE : constant Node_Id := Next (Then_DE);
7811 Bignum_Operands := False;
7813 Minimize_Eliminate_Overflows
7814 (Then_DE, Lo, Hi, Top_Level => False);
7816 if Lo = No_Uint then
7817 Bignum_Operands := True;
7820 Minimize_Eliminate_Overflows
7821 (Else_DE, Rlo, Rhi, Top_Level => False);
7823 if Rlo = No_Uint then
7824 Bignum_Operands := True;
7826 Long_Long_Integer_Operands :=
7827 Etype (Then_DE) = LLIB or else Etype (Else_DE) = LLIB;
7833 -- If at least one of our operands is now Bignum, we must rebuild
7834 -- the if expression to use Bignum operands. We will analyze the
7835 -- rebuilt if expression with overflow checks off, since once we
7836 -- are in bignum mode, we are all done with overflow checks.
7838 if Bignum_Operands then
7840 Make_If_Expression (Loc,
7841 Expressions => New_List (
7842 Remove_Head (Expressions (N)),
7843 Convert_To_Bignum (Then_DE),
7844 Convert_To_Bignum (Else_DE)),
7845 Is_Elsif => Is_Elsif (N)));
7847 Reanalyze (RTE (RE_Bignum), Suppress => True);
7849 -- If we have no Long_Long_Integer operands, then we are in result
7850 -- range, since it means that none of our operands felt the need
7851 -- to worry about overflow (otherwise it would have already been
7852 -- converted to long long integer or bignum). We reexpand to
7853 -- complete the expansion of the if expression (but we do not
7854 -- need to reanalyze).
7856 elsif not Long_Long_Integer_Operands then
7857 Set_Do_Overflow_Check (N, False);
7860 -- Otherwise convert us to long long integer mode. Note that we
7861 -- don't need any further overflow checking at this level.
7864 Convert_To_And_Rewrite (LLIB, Then_DE);
7865 Convert_To_And_Rewrite (LLIB, Else_DE);
7866 Set_Etype (N, LLIB);
7868 -- Now reanalyze with overflow checks off
7870 Set_Do_Overflow_Check (N, False);
7871 Reanalyze (LLIB, Suppress => True);
7877 -- Here for case expression
7879 elsif Nkind (N) = N_Case_Expression then
7880 Bignum_Operands := False;
7881 Long_Long_Integer_Operands := False;
7887 -- Loop through expressions applying recursive call
7889 Alt := First (Alternatives (N));
7890 while Present (Alt) loop
7892 Aexp : constant Node_Id := Expression (Alt);
7895 Minimize_Eliminate_Overflows
7896 (Aexp, Lo, Hi, Top_Level => False);
7898 if Lo = No_Uint then
7899 Bignum_Operands := True;
7900 elsif Etype (Aexp) = LLIB then
7901 Long_Long_Integer_Operands := True;
7908 -- If we have no bignum or long long integer operands, it means
7909 -- that none of our dependent expressions could raise overflow.
7910 -- In this case, we simply return with no changes except for
7911 -- resetting the overflow flag, since we are done with overflow
7912 -- checks for this node. We will reexpand to get the needed
7913 -- expansion for the case expression, but we do not need to
7914 -- reanalyze, since nothing has changed.
7916 if not (Bignum_Operands or Long_Long_Integer_Operands) then
7917 Set_Do_Overflow_Check (N, False);
7918 Reexpand (Suppress => True);
7920 -- Otherwise we are going to rebuild the case expression using
7921 -- either bignum or long long integer operands throughout.
7930 New_Alts := New_List;
7931 Alt := First (Alternatives (N));
7932 while Present (Alt) loop
7933 if Bignum_Operands then
7934 New_Exp := Convert_To_Bignum (Expression (Alt));
7935 Rtype := RTE (RE_Bignum);
7937 New_Exp := Convert_To (LLIB, Expression (Alt));
7941 Append_To (New_Alts,
7942 Make_Case_Expression_Alternative (Sloc (Alt),
7944 Discrete_Choices => Discrete_Choices (Alt),
7945 Expression => New_Exp));
7951 Make_Case_Expression (Loc,
7952 Expression => Expression (N),
7953 Alternatives => New_Alts));
7955 Reanalyze (Rtype, Suppress => True);
7963 -- If we have an arithmetic operator we make recursive calls on the
7964 -- operands to get the ranges (and to properly process the subtree
7965 -- that lies below us).
7967 Minimize_Eliminate_Overflows
7968 (Right_Opnd (N), Rlo, Rhi, Top_Level => False);
7971 Minimize_Eliminate_Overflows
7972 (Left_Opnd (N), Llo, Lhi, Top_Level => False);
7975 -- Record if we have Long_Long_Integer operands
7977 Long_Long_Integer_Operands :=
7978 Etype (Right_Opnd (N)) = LLIB
7979 or else (Binary and then Etype (Left_Opnd (N)) = LLIB);
7981 -- If either operand is a bignum, then result will be a bignum and we
7982 -- don't need to do any range analysis. As previously discussed we could
7983 -- do range analysis in such cases, but it could mean working with giant
7984 -- numbers at compile time for very little gain (the number of cases
7985 -- in which we could slip back from bignum mode is small).
7987 if Rlo = No_Uint or else (Binary and then Llo = No_Uint) then
7990 Bignum_Operands := True;
7992 -- Otherwise compute result range
7995 Bignum_Operands := False;
8003 Hi := UI_Max (abs Rlo, abs Rhi);
8015 -- If the right operand can only be zero, set 0..0
8017 if Rlo = 0 and then Rhi = 0 then
8021 -- Possible bounds of division must come from dividing end
8022 -- values of the input ranges (four possibilities), provided
8023 -- zero is not included in the possible values of the right
8026 -- Otherwise, we just consider two intervals of values for
8027 -- the right operand: the interval of negative values (up to
8028 -- -1) and the interval of positive values (starting at 1).
8029 -- Since division by 1 is the identity, and division by -1
8030 -- is negation, we get all possible bounds of division in that
8031 -- case by considering:
8032 -- - all values from the division of end values of input
8034 -- - the end values of the left operand;
8035 -- - the negation of the end values of the left operand.
8039 Mrk : constant Uintp.Save_Mark := Mark;
8040 -- Mark so we can release the RR and Ev values
8048 -- Discard extreme values of zero for the divisor, since
8049 -- they will simply result in an exception in any case.
8057 -- Compute possible bounds coming from dividing end
8058 -- values of the input ranges.
8065 Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4));
8066 Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4));
8068 -- If the right operand can be both negative or positive,
8069 -- include the end values of the left operand in the
8070 -- extreme values, as well as their negation.
8072 if Rlo < 0 and then Rhi > 0 then
8079 UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4)));
8081 UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4)));
8084 -- Release the RR and Ev values
8086 Release_And_Save (Mrk, Lo, Hi);
8094 -- Discard negative values for the exponent, since they will
8095 -- simply result in an exception in any case.
8103 -- Estimate number of bits in result before we go computing
8104 -- giant useless bounds. Basically the number of bits in the
8105 -- result is the number of bits in the base multiplied by the
8106 -- value of the exponent. If this is big enough that the result
8107 -- definitely won't fit in Long_Long_Integer, switch to bignum
8108 -- mode immediately, and avoid computing giant bounds.
8110 -- The comparison here is approximate, but conservative, it
8111 -- only clicks on cases that are sure to exceed the bounds.
8113 if Num_Bits (UI_Max (abs Llo, abs Lhi)) * Rhi + 1 > 100 then
8117 -- If right operand is zero then result is 1
8124 -- High bound comes either from exponentiation of largest
8125 -- positive value to largest exponent value, or from
8126 -- the exponentiation of most negative value to an
8140 if Rhi mod 2 = 0 then
8143 Hi2 := Llo ** (Rhi - 1);
8149 Hi := UI_Max (Hi1, Hi2);
8152 -- Result can only be negative if base can be negative
8155 if Rhi mod 2 = 0 then
8156 Lo := Llo ** (Rhi - 1);
8161 -- Otherwise low bound is minimum ** minimum
8178 Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1;
8179 -- This is the maximum absolute value of the result
8185 -- The result depends only on the sign and magnitude of
8186 -- the right operand, it does not depend on the sign or
8187 -- magnitude of the left operand.
8200 when N_Op_Multiply =>
8202 -- Possible bounds of multiplication must come from multiplying
8203 -- end values of the input ranges (four possibilities).
8206 Mrk : constant Uintp.Save_Mark := Mark;
8207 -- Mark so we can release the Ev values
8209 Ev1 : constant Uint := Llo * Rlo;
8210 Ev2 : constant Uint := Llo * Rhi;
8211 Ev3 : constant Uint := Lhi * Rlo;
8212 Ev4 : constant Uint := Lhi * Rhi;
8215 Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4));
8216 Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4));
8218 -- Release the Ev values
8220 Release_And_Save (Mrk, Lo, Hi);
8223 -- Plus operator (affirmation)
8233 Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1;
8234 -- This is the maximum absolute value of the result. Note
8235 -- that the result range does not depend on the sign of the
8242 -- Case of left operand negative, which results in a range
8243 -- of -Maxabs .. 0 for those negative values. If there are
8244 -- no negative values then Lo value of result is always 0.
8250 -- Case of left operand positive
8259 when N_Op_Subtract =>
8263 -- Nothing else should be possible
8266 raise Program_Error;
8270 -- Here for the case where we have not rewritten anything (no bignum
8271 -- operands or long long integer operands), and we know the result.
8272 -- If we know we are in the result range, and we do not have Bignum
8273 -- operands or Long_Long_Integer operands, we can just reexpand with
8274 -- overflow checks turned off (since we know we cannot have overflow).
8275 -- As always the reexpansion is required to complete expansion of the
8276 -- operator, but we do not need to reanalyze, and we prevent recursion
8277 -- by suppressing the check.
8279 if not (Bignum_Operands or Long_Long_Integer_Operands)
8280 and then In_Result_Range
8282 Set_Do_Overflow_Check (N, False);
8283 Reexpand (Suppress => True);
8286 -- Here we know that we are not in the result range, and in the general
8287 -- case we will move into either the Bignum or Long_Long_Integer domain
8288 -- to compute the result. However, there is one exception. If we are
8289 -- at the top level, and we do not have Bignum or Long_Long_Integer
8290 -- operands, we will have to immediately convert the result back to
8291 -- the result type, so there is no point in Bignum/Long_Long_Integer
8295 and then not (Bignum_Operands or Long_Long_Integer_Operands)
8297 -- One further refinement. If we are at the top level, but our parent
8298 -- is a type conversion, then go into bignum or long long integer node
8299 -- since the result will be converted to that type directly without
8300 -- going through the result type, and we may avoid an overflow. This
8301 -- is the case for example of Long_Long_Integer (A ** 4), where A is
8302 -- of type Integer, and the result A ** 4 fits in Long_Long_Integer
8303 -- but does not fit in Integer.
8305 and then Nkind (Parent (N)) /= N_Type_Conversion
8307 -- Here keep original types, but we need to complete analysis
8309 -- One subtlety. We can't just go ahead and do an analyze operation
8310 -- here because it will cause recursion into the whole MINIMIZED/
8311 -- ELIMINATED overflow processing which is not what we want. Here
8312 -- we are at the top level, and we need a check against the result
8313 -- mode (i.e. we want to use STRICT mode). So do exactly that.
8314 -- Also, we have not modified the node, so this is a case where
8315 -- we need to reexpand, but not reanalyze.
8320 -- Cases where we do the operation in Bignum mode. This happens either
8321 -- because one of our operands is in Bignum mode already, or because
8322 -- the computed bounds are outside the bounds of Long_Long_Integer,
8323 -- which in some cases can be indicated by Hi and Lo being No_Uint.
8325 -- Note: we could do better here and in some cases switch back from
8326 -- Bignum mode to normal mode, e.g. big mod 2 must be in the range
8327 -- 0 .. 1, but the cases are rare and it is not worth the effort.
8328 -- Failing to do this switching back is only an efficiency issue.
8330 elsif Lo = No_Uint or else Lo < LLLo or else Hi > LLHi then
8332 -- OK, we are definitely outside the range of Long_Long_Integer. The
8333 -- question is whether to move to Bignum mode, or stay in the domain
8334 -- of Long_Long_Integer, signalling that an overflow check is needed.
8336 -- Obviously in MINIMIZED mode we stay with LLI, since we are not in
8337 -- the Bignum business. In ELIMINATED mode, we will normally move
8338 -- into Bignum mode, but there is an exception if neither of our
8339 -- operands is Bignum now, and we are at the top level (Top_Level
8340 -- set True). In this case, there is no point in moving into Bignum
8341 -- mode to prevent overflow if the caller will immediately convert
8342 -- the Bignum value back to LLI with an overflow check. It's more
8343 -- efficient to stay in LLI mode with an overflow check (if needed)
8345 if Check_Mode = Minimized
8346 or else (Top_Level and not Bignum_Operands)
8348 if Do_Overflow_Check (N) then
8349 Enable_Overflow_Check (N);
8352 -- The result now has to be in Long_Long_Integer mode, so adjust
8353 -- the possible range to reflect this. Note these calls also
8354 -- change No_Uint values from the top level case to LLI bounds.
8359 -- Otherwise we are in ELIMINATED mode and we switch to Bignum mode
8362 pragma Assert (Check_Mode = Eliminated);
8371 Fent := RTE (RE_Big_Abs);
8374 Fent := RTE (RE_Big_Add);
8377 Fent := RTE (RE_Big_Div);
8380 Fent := RTE (RE_Big_Exp);
8383 Fent := RTE (RE_Big_Neg);
8386 Fent := RTE (RE_Big_Mod);
8388 when N_Op_Multiply =>
8389 Fent := RTE (RE_Big_Mul);
8392 Fent := RTE (RE_Big_Rem);
8394 when N_Op_Subtract =>
8395 Fent := RTE (RE_Big_Sub);
8397 -- Anything else is an internal error, this includes the
8398 -- N_Op_Plus case, since how can plus cause the result
8399 -- to be out of range if the operand is in range?
8402 raise Program_Error;
8405 -- Construct argument list for Bignum call, converting our
8406 -- operands to Bignum form if they are not already there.
8411 Append_To (Args, Convert_To_Bignum (Left_Opnd (N)));
8414 Append_To (Args, Convert_To_Bignum (Right_Opnd (N)));
8416 -- Now rewrite the arithmetic operator with a call to the
8417 -- corresponding bignum function.
8420 Make_Function_Call (Loc,
8421 Name => New_Occurrence_Of (Fent, Loc),
8422 Parameter_Associations => Args));
8423 Reanalyze (RTE (RE_Bignum), Suppress => True);
8425 -- Indicate result is Bignum mode
8433 -- Otherwise we are in range of Long_Long_Integer, so no overflow
8434 -- check is required, at least not yet.
8437 Set_Do_Overflow_Check (N, False);
8440 -- Here we are not in Bignum territory, but we may have long long
8441 -- integer operands that need special handling. First a special check:
8442 -- If an exponentiation operator exponent is of type Long_Long_Integer,
8443 -- it means we converted it to prevent overflow, but exponentiation
8444 -- requires a Natural right operand, so convert it back to Natural.
8445 -- This conversion may raise an exception which is fine.
8447 if Nkind (N) = N_Op_Expon and then Etype (Right_Opnd (N)) = LLIB then
8448 Convert_To_And_Rewrite (Standard_Natural, Right_Opnd (N));
8451 -- Here we will do the operation in Long_Long_Integer. We do this even
8452 -- if we know an overflow check is required, better to do this in long
8453 -- long integer mode, since we are less likely to overflow.
8455 -- Convert right or only operand to Long_Long_Integer, except that
8456 -- we do not touch the exponentiation right operand.
8458 if Nkind (N) /= N_Op_Expon then
8459 Convert_To_And_Rewrite (LLIB, Right_Opnd (N));
8462 -- Convert left operand to Long_Long_Integer for binary case
8465 Convert_To_And_Rewrite (LLIB, Left_Opnd (N));
8468 -- Reset node to unanalyzed
8470 Set_Analyzed (N, False);
8471 Set_Etype (N, Empty);
8472 Set_Entity (N, Empty);
8474 -- Now analyze this new node. This reanalysis will complete processing
8475 -- for the node. In particular we will complete the expansion of an
8476 -- exponentiation operator (e.g. changing A ** 2 to A * A), and also
8477 -- we will complete any division checks (since we have not changed the
8478 -- setting of the Do_Division_Check flag).
8480 -- We do this reanalysis in STRICT mode to avoid recursion into the
8481 -- MINIMIZED/ELIMINATED handling, since we are now done with that.
8484 SG : constant Overflow_Mode_Type :=
8485 Scope_Suppress.Overflow_Mode_General;
8486 SA : constant Overflow_Mode_Type :=
8487 Scope_Suppress.Overflow_Mode_Assertions;
8490 Scope_Suppress.Overflow_Mode_General := Strict;
8491 Scope_Suppress.Overflow_Mode_Assertions := Strict;
8493 if not Do_Overflow_Check (N) then
8494 Reanalyze (LLIB, Suppress => True);
8499 Scope_Suppress.Overflow_Mode_General := SG;
8500 Scope_Suppress.Overflow_Mode_Assertions := SA;
8502 end Minimize_Eliminate_Overflows;
8504 -------------------------
8505 -- Overflow_Check_Mode --
8506 -------------------------
8508 function Overflow_Check_Mode return Overflow_Mode_Type is
8510 if In_Assertion_Expr = 0 then
8511 return Scope_Suppress.Overflow_Mode_General;
8513 return Scope_Suppress.Overflow_Mode_Assertions;
8515 end Overflow_Check_Mode;
8517 --------------------------------
8518 -- Overflow_Checks_Suppressed --
8519 --------------------------------
8521 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
8523 if Present (E) and then Checks_May_Be_Suppressed (E) then
8524 return Is_Check_Suppressed (E, Overflow_Check);
8526 return Scope_Suppress.Suppress (Overflow_Check);
8528 end Overflow_Checks_Suppressed;
8530 ---------------------------------
8531 -- Predicate_Checks_Suppressed --
8532 ---------------------------------
8534 function Predicate_Checks_Suppressed (E : Entity_Id) return Boolean is
8536 if Present (E) and then Checks_May_Be_Suppressed (E) then
8537 return Is_Check_Suppressed (E, Predicate_Check);
8539 return Scope_Suppress.Suppress (Predicate_Check);
8541 end Predicate_Checks_Suppressed;
8543 -----------------------------
8544 -- Range_Checks_Suppressed --
8545 -----------------------------
8547 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
8550 if Kill_Range_Checks (E) then
8553 elsif Checks_May_Be_Suppressed (E) then
8554 return Is_Check_Suppressed (E, Range_Check);
8558 return Scope_Suppress.Suppress (Range_Check);
8559 end Range_Checks_Suppressed;
8561 -----------------------------------------
8562 -- Range_Or_Validity_Checks_Suppressed --
8563 -----------------------------------------
8565 -- Note: the coding would be simpler here if we simply made appropriate
8566 -- calls to Range/Validity_Checks_Suppressed, but that would result in
8567 -- duplicated checks which we prefer to avoid.
8569 function Range_Or_Validity_Checks_Suppressed
8570 (Expr : Node_Id) return Boolean
8573 -- Immediate return if scope checks suppressed for either check
8575 if Scope_Suppress.Suppress (Range_Check)
8577 Scope_Suppress.Suppress (Validity_Check)
8582 -- If no expression, that's odd, decide that checks are suppressed,
8583 -- since we don't want anyone trying to do checks in this case, which
8584 -- is most likely the result of some other error.
8590 -- Expression is present, so perform suppress checks on type
8593 Typ : constant Entity_Id := Etype (Expr);
8595 if Checks_May_Be_Suppressed (Typ)
8596 and then (Is_Check_Suppressed (Typ, Range_Check)
8598 Is_Check_Suppressed (Typ, Validity_Check))
8604 -- If expression is an entity name, perform checks on this entity
8606 if Is_Entity_Name (Expr) then
8608 Ent : constant Entity_Id := Entity (Expr);
8610 if Checks_May_Be_Suppressed (Ent) then
8611 return Is_Check_Suppressed (Ent, Range_Check)
8612 or else Is_Check_Suppressed (Ent, Validity_Check);
8617 -- If we fall through, no checks suppressed
8620 end Range_Or_Validity_Checks_Suppressed;
8626 procedure Remove_Checks (Expr : Node_Id) is
8627 function Process (N : Node_Id) return Traverse_Result;
8628 -- Process a single node during the traversal
8630 procedure Traverse is new Traverse_Proc (Process);
8631 -- The traversal procedure itself
8637 function Process (N : Node_Id) return Traverse_Result is
8639 if Nkind (N) not in N_Subexpr then
8643 Set_Do_Range_Check (N, False);
8647 Traverse (Left_Opnd (N));
8650 when N_Attribute_Reference =>
8651 Set_Do_Overflow_Check (N, False);
8653 when N_Function_Call =>
8654 Set_Do_Tag_Check (N, False);
8657 Set_Do_Overflow_Check (N, False);
8661 Set_Do_Division_Check (N, False);
8664 Set_Do_Length_Check (N, False);
8667 Set_Do_Division_Check (N, False);
8670 Set_Do_Length_Check (N, False);
8673 Set_Do_Division_Check (N, False);
8676 Set_Do_Length_Check (N, False);
8683 Traverse (Left_Opnd (N));
8686 when N_Selected_Component =>
8687 Set_Do_Discriminant_Check (N, False);
8689 when N_Type_Conversion =>
8690 Set_Do_Length_Check (N, False);
8691 Set_Do_Tag_Check (N, False);
8692 Set_Do_Overflow_Check (N, False);
8701 -- Start of processing for Remove_Checks
8707 ----------------------------
8708 -- Selected_Length_Checks --
8709 ----------------------------
8711 function Selected_Length_Checks
8713 Target_Typ : Entity_Id;
8714 Source_Typ : Entity_Id;
8715 Warn_Node : Node_Id) return Check_Result
8717 Loc : constant Source_Ptr := Sloc (Ck_Node);
8720 Expr_Actual : Node_Id;
8722 Cond : Node_Id := Empty;
8723 Do_Access : Boolean := False;
8724 Wnode : Node_Id := Warn_Node;
8725 Ret_Result : Check_Result := (Empty, Empty);
8726 Num_Checks : Natural := 0;
8728 procedure Add_Check (N : Node_Id);
8729 -- Adds the action given to Ret_Result if N is non-Empty
8731 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
8732 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
8733 -- Comments required ???
8735 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
8736 -- True for equal literals and for nodes that denote the same constant
8737 -- entity, even if its value is not a static constant. This includes the
8738 -- case of a discriminal reference within an init proc. Removes some
8739 -- obviously superfluous checks.
8741 function Length_E_Cond
8742 (Exptyp : Entity_Id;
8744 Indx : Nat) return Node_Id;
8745 -- Returns expression to compute:
8746 -- Typ'Length /= Exptyp'Length
8748 function Length_N_Cond
8751 Indx : Nat) return Node_Id;
8752 -- Returns expression to compute:
8753 -- Typ'Length /= Expr'Length
8759 procedure Add_Check (N : Node_Id) is
8763 -- For now, ignore attempt to place more than two checks ???
8764 -- This is really worrisome, are we really discarding checks ???
8766 if Num_Checks = 2 then
8770 pragma Assert (Num_Checks <= 1);
8771 Num_Checks := Num_Checks + 1;
8772 Ret_Result (Num_Checks) := N;
8780 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
8781 SE : constant Entity_Id := Scope (E);
8783 E1 : Entity_Id := E;
8786 if Ekind (Scope (E)) = E_Record_Type
8787 and then Has_Discriminants (Scope (E))
8789 N := Build_Discriminal_Subtype_Of_Component (E);
8792 Insert_Action (Ck_Node, N);
8793 E1 := Defining_Identifier (N);
8797 if Ekind (E1) = E_String_Literal_Subtype then
8799 Make_Integer_Literal (Loc,
8800 Intval => String_Literal_Length (E1));
8802 elsif SE /= Standard_Standard
8803 and then Ekind (Scope (SE)) = E_Protected_Type
8804 and then Has_Discriminants (Scope (SE))
8805 and then Has_Completion (Scope (SE))
8806 and then not Inside_Init_Proc
8808 -- If the type whose length is needed is a private component
8809 -- constrained by a discriminant, we must expand the 'Length
8810 -- attribute into an explicit computation, using the discriminal
8811 -- of the current protected operation. This is because the actual
8812 -- type of the prival is constructed after the protected opera-
8813 -- tion has been fully expanded.
8816 Indx_Type : Node_Id;
8819 Do_Expand : Boolean := False;
8822 Indx_Type := First_Index (E);
8824 for J in 1 .. Indx - 1 loop
8825 Next_Index (Indx_Type);
8828 Get_Index_Bounds (Indx_Type, Lo, Hi);
8830 if Nkind (Lo) = N_Identifier
8831 and then Ekind (Entity (Lo)) = E_In_Parameter
8833 Lo := Get_Discriminal (E, Lo);
8837 if Nkind (Hi) = N_Identifier
8838 and then Ekind (Entity (Hi)) = E_In_Parameter
8840 Hi := Get_Discriminal (E, Hi);
8845 if not Is_Entity_Name (Lo) then
8846 Lo := Duplicate_Subexpr_No_Checks (Lo);
8849 if not Is_Entity_Name (Hi) then
8850 Lo := Duplicate_Subexpr_No_Checks (Hi);
8856 Make_Op_Subtract (Loc,
8860 Right_Opnd => Make_Integer_Literal (Loc, 1));
8865 Make_Attribute_Reference (Loc,
8866 Attribute_Name => Name_Length,
8868 New_Occurrence_Of (E1, Loc));
8871 Set_Expressions (N, New_List (
8872 Make_Integer_Literal (Loc, Indx)));
8881 Make_Attribute_Reference (Loc,
8882 Attribute_Name => Name_Length,
8884 New_Occurrence_Of (E1, Loc));
8887 Set_Expressions (N, New_List (
8888 Make_Integer_Literal (Loc, Indx)));
8899 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
8902 Make_Attribute_Reference (Loc,
8903 Attribute_Name => Name_Length,
8905 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
8906 Expressions => New_List (
8907 Make_Integer_Literal (Loc, Indx)));
8914 function Length_E_Cond
8915 (Exptyp : Entity_Id;
8917 Indx : Nat) return Node_Id
8922 Left_Opnd => Get_E_Length (Typ, Indx),
8923 Right_Opnd => Get_E_Length (Exptyp, Indx));
8930 function Length_N_Cond
8933 Indx : Nat) return Node_Id
8938 Left_Opnd => Get_E_Length (Typ, Indx),
8939 Right_Opnd => Get_N_Length (Expr, Indx));
8946 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
8949 (Nkind (L) = N_Integer_Literal
8950 and then Nkind (R) = N_Integer_Literal
8951 and then Intval (L) = Intval (R))
8955 and then Ekind (Entity (L)) = E_Constant
8956 and then ((Is_Entity_Name (R)
8957 and then Entity (L) = Entity (R))
8959 (Nkind (R) = N_Type_Conversion
8960 and then Is_Entity_Name (Expression (R))
8961 and then Entity (L) = Entity (Expression (R)))))
8965 and then Ekind (Entity (R)) = E_Constant
8966 and then Nkind (L) = N_Type_Conversion
8967 and then Is_Entity_Name (Expression (L))
8968 and then Entity (R) = Entity (Expression (L)))
8972 and then Is_Entity_Name (R)
8973 and then Entity (L) = Entity (R)
8974 and then Ekind (Entity (L)) = E_In_Parameter
8975 and then Inside_Init_Proc);
8978 -- Start of processing for Selected_Length_Checks
8981 if not Expander_Active then
8985 if Target_Typ = Any_Type
8986 or else Target_Typ = Any_Composite
8987 or else Raises_Constraint_Error (Ck_Node)
8996 T_Typ := Target_Typ;
8998 if No (Source_Typ) then
8999 S_Typ := Etype (Ck_Node);
9001 S_Typ := Source_Typ;
9004 if S_Typ = Any_Type or else S_Typ = Any_Composite then
9008 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
9009 S_Typ := Designated_Type (S_Typ);
9010 T_Typ := Designated_Type (T_Typ);
9013 -- A simple optimization for the null case
9015 if Known_Null (Ck_Node) then
9020 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
9021 if Is_Constrained (T_Typ) then
9023 -- The checking code to be generated will freeze the corresponding
9024 -- array type. However, we must freeze the type now, so that the
9025 -- freeze node does not appear within the generated if expression,
9028 Freeze_Before (Ck_Node, T_Typ);
9030 Expr_Actual := Get_Referenced_Object (Ck_Node);
9031 Exptyp := Get_Actual_Subtype (Ck_Node);
9033 if Is_Access_Type (Exptyp) then
9034 Exptyp := Designated_Type (Exptyp);
9037 -- String_Literal case. This needs to be handled specially be-
9038 -- cause no index types are available for string literals. The
9039 -- condition is simply:
9041 -- T_Typ'Length = string-literal-length
9043 if Nkind (Expr_Actual) = N_String_Literal
9044 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
9048 Left_Opnd => Get_E_Length (T_Typ, 1),
9050 Make_Integer_Literal (Loc,
9052 String_Literal_Length (Etype (Expr_Actual))));
9054 -- General array case. Here we have a usable actual subtype for
9055 -- the expression, and the condition is built from the two types
9058 -- T_Typ'Length /= Exptyp'Length or else
9059 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
9060 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
9063 elsif Is_Constrained (Exptyp) then
9065 Ndims : constant Nat := Number_Dimensions (T_Typ);
9078 -- At the library level, we need to ensure that the type of
9079 -- the object is elaborated before the check itself is
9080 -- emitted. This is only done if the object is in the
9081 -- current compilation unit, otherwise the type is frozen
9082 -- and elaborated in its unit.
9084 if Is_Itype (Exptyp)
9086 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
9088 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
9089 and then In_Open_Scopes (Scope (Exptyp))
9091 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
9092 Set_Itype (Ref_Node, Exptyp);
9093 Insert_Action (Ck_Node, Ref_Node);
9096 L_Index := First_Index (T_Typ);
9097 R_Index := First_Index (Exptyp);
9099 for Indx in 1 .. Ndims loop
9100 if not (Nkind (L_Index) = N_Raise_Constraint_Error
9102 Nkind (R_Index) = N_Raise_Constraint_Error)
9104 Get_Index_Bounds (L_Index, L_Low, L_High);
9105 Get_Index_Bounds (R_Index, R_Low, R_High);
9107 -- Deal with compile time length check. Note that we
9108 -- skip this in the access case, because the access
9109 -- value may be null, so we cannot know statically.
9112 and then Compile_Time_Known_Value (L_Low)
9113 and then Compile_Time_Known_Value (L_High)
9114 and then Compile_Time_Known_Value (R_Low)
9115 and then Compile_Time_Known_Value (R_High)
9117 if Expr_Value (L_High) >= Expr_Value (L_Low) then
9118 L_Length := Expr_Value (L_High) -
9119 Expr_Value (L_Low) + 1;
9121 L_Length := UI_From_Int (0);
9124 if Expr_Value (R_High) >= Expr_Value (R_Low) then
9125 R_Length := Expr_Value (R_High) -
9126 Expr_Value (R_Low) + 1;
9128 R_Length := UI_From_Int (0);
9131 if L_Length > R_Length then
9133 (Compile_Time_Constraint_Error
9134 (Wnode, "too few elements for}??", T_Typ));
9136 elsif L_Length < R_Length then
9138 (Compile_Time_Constraint_Error
9139 (Wnode, "too many elements for}??", T_Typ));
9142 -- The comparison for an individual index subtype
9143 -- is omitted if the corresponding index subtypes
9144 -- statically match, since the result is known to
9145 -- be true. Note that this test is worth while even
9146 -- though we do static evaluation, because non-static
9147 -- subtypes can statically match.
9150 Subtypes_Statically_Match
9151 (Etype (L_Index), Etype (R_Index))
9154 (Same_Bounds (L_Low, R_Low)
9155 and then Same_Bounds (L_High, R_High))
9158 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
9167 -- Handle cases where we do not get a usable actual subtype that
9168 -- is constrained. This happens for example in the function call
9169 -- and explicit dereference cases. In these cases, we have to get
9170 -- the length or range from the expression itself, making sure we
9171 -- do not evaluate it more than once.
9173 -- Here Ck_Node is the original expression, or more properly the
9174 -- result of applying Duplicate_Expr to the original tree, forcing
9175 -- the result to be a name.
9179 Ndims : constant Nat := Number_Dimensions (T_Typ);
9182 -- Build the condition for the explicit dereference case
9184 for Indx in 1 .. Ndims loop
9186 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
9193 -- Construct the test and insert into the tree
9195 if Present (Cond) then
9197 Cond := Guard_Access (Cond, Loc, Ck_Node);
9201 (Make_Raise_Constraint_Error (Loc,
9203 Reason => CE_Length_Check_Failed));
9207 end Selected_Length_Checks;
9209 ---------------------------
9210 -- Selected_Range_Checks --
9211 ---------------------------
9213 function Selected_Range_Checks
9215 Target_Typ : Entity_Id;
9216 Source_Typ : Entity_Id;
9217 Warn_Node : Node_Id) return Check_Result
9219 Loc : constant Source_Ptr := Sloc (Ck_Node);
9222 Expr_Actual : Node_Id;
9224 Cond : Node_Id := Empty;
9225 Do_Access : Boolean := False;
9226 Wnode : Node_Id := Warn_Node;
9227 Ret_Result : Check_Result := (Empty, Empty);
9228 Num_Checks : Integer := 0;
9230 procedure Add_Check (N : Node_Id);
9231 -- Adds the action given to Ret_Result if N is non-Empty
9233 function Discrete_Range_Cond
9235 Typ : Entity_Id) return Node_Id;
9236 -- Returns expression to compute:
9237 -- Low_Bound (Expr) < Typ'First
9239 -- High_Bound (Expr) > Typ'Last
9241 function Discrete_Expr_Cond
9243 Typ : Entity_Id) return Node_Id;
9244 -- Returns expression to compute:
9249 function Get_E_First_Or_Last
9253 Nam : Name_Id) return Node_Id;
9254 -- Returns an attribute reference
9255 -- E'First or E'Last
9256 -- with a source location of Loc.
9258 -- Nam is Name_First or Name_Last, according to which attribute is
9259 -- desired. If Indx is non-zero, it is passed as a literal in the
9260 -- Expressions of the attribute reference (identifying the desired
9261 -- array dimension).
9263 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
9264 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
9265 -- Returns expression to compute:
9266 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
9268 function Range_E_Cond
9269 (Exptyp : Entity_Id;
9273 -- Returns expression to compute:
9274 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
9276 function Range_Equal_E_Cond
9277 (Exptyp : Entity_Id;
9279 Indx : Nat) return Node_Id;
9280 -- Returns expression to compute:
9281 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
9283 function Range_N_Cond
9286 Indx : Nat) return Node_Id;
9287 -- Return expression to compute:
9288 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
9294 procedure Add_Check (N : Node_Id) is
9298 -- For now, ignore attempt to place more than 2 checks ???
9300 if Num_Checks = 2 then
9304 pragma Assert (Num_Checks <= 1);
9305 Num_Checks := Num_Checks + 1;
9306 Ret_Result (Num_Checks) := N;
9310 -------------------------
9311 -- Discrete_Expr_Cond --
9312 -------------------------
9314 function Discrete_Expr_Cond
9316 Typ : Entity_Id) return Node_Id
9324 Convert_To (Base_Type (Typ),
9325 Duplicate_Subexpr_No_Checks (Expr)),
9327 Convert_To (Base_Type (Typ),
9328 Get_E_First_Or_Last (Loc, Typ, 0, Name_First))),
9333 Convert_To (Base_Type (Typ),
9334 Duplicate_Subexpr_No_Checks (Expr)),
9338 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last))));
9339 end Discrete_Expr_Cond;
9341 -------------------------
9342 -- Discrete_Range_Cond --
9343 -------------------------
9345 function Discrete_Range_Cond
9347 Typ : Entity_Id) return Node_Id
9349 LB : Node_Id := Low_Bound (Expr);
9350 HB : Node_Id := High_Bound (Expr);
9352 Left_Opnd : Node_Id;
9353 Right_Opnd : Node_Id;
9356 if Nkind (LB) = N_Identifier
9357 and then Ekind (Entity (LB)) = E_Discriminant
9359 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
9366 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
9371 Get_E_First_Or_Last (Loc, Typ, 0, Name_First)));
9373 if Nkind (HB) = N_Identifier
9374 and then Ekind (Entity (HB)) = E_Discriminant
9376 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
9383 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
9388 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last)));
9390 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
9391 end Discrete_Range_Cond;
9393 -------------------------
9394 -- Get_E_First_Or_Last --
9395 -------------------------
9397 function Get_E_First_Or_Last
9401 Nam : Name_Id) return Node_Id
9406 Exprs := New_List (Make_Integer_Literal (Loc, UI_From_Int (Indx)));
9411 return Make_Attribute_Reference (Loc,
9412 Prefix => New_Occurrence_Of (E, Loc),
9413 Attribute_Name => Nam,
9414 Expressions => Exprs);
9415 end Get_E_First_Or_Last;
9421 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
9424 Make_Attribute_Reference (Loc,
9425 Attribute_Name => Name_First,
9427 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
9428 Expressions => New_List (
9429 Make_Integer_Literal (Loc, Indx)));
9436 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
9439 Make_Attribute_Reference (Loc,
9440 Attribute_Name => Name_Last,
9442 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
9443 Expressions => New_List (
9444 Make_Integer_Literal (Loc, Indx)));
9451 function Range_E_Cond
9452 (Exptyp : Entity_Id;
9454 Indx : Nat) return Node_Id
9462 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
9464 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
9469 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
9471 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
9474 ------------------------
9475 -- Range_Equal_E_Cond --
9476 ------------------------
9478 function Range_Equal_E_Cond
9479 (Exptyp : Entity_Id;
9481 Indx : Nat) return Node_Id
9489 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
9491 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
9496 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
9498 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
9499 end Range_Equal_E_Cond;
9505 function Range_N_Cond
9508 Indx : Nat) return Node_Id
9516 Get_N_First (Expr, Indx),
9518 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
9523 Get_N_Last (Expr, Indx),
9525 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
9528 -- Start of processing for Selected_Range_Checks
9531 if not Expander_Active then
9535 if Target_Typ = Any_Type
9536 or else Target_Typ = Any_Composite
9537 or else Raises_Constraint_Error (Ck_Node)
9546 T_Typ := Target_Typ;
9548 if No (Source_Typ) then
9549 S_Typ := Etype (Ck_Node);
9551 S_Typ := Source_Typ;
9554 if S_Typ = Any_Type or else S_Typ = Any_Composite then
9558 -- The order of evaluating T_Typ before S_Typ seems to be critical
9559 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
9560 -- in, and since Node can be an N_Range node, it might be invalid.
9561 -- Should there be an assert check somewhere for taking the Etype of
9562 -- an N_Range node ???
9564 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
9565 S_Typ := Designated_Type (S_Typ);
9566 T_Typ := Designated_Type (T_Typ);
9569 -- A simple optimization for the null case
9571 if Known_Null (Ck_Node) then
9576 -- For an N_Range Node, check for a null range and then if not
9577 -- null generate a range check action.
9579 if Nkind (Ck_Node) = N_Range then
9581 -- There's no point in checking a range against itself
9583 if Ck_Node = Scalar_Range (T_Typ) then
9588 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
9589 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
9590 Known_T_LB : constant Boolean := Compile_Time_Known_Value (T_LB);
9591 Known_T_HB : constant Boolean := Compile_Time_Known_Value (T_HB);
9593 LB : Node_Id := Low_Bound (Ck_Node);
9594 HB : Node_Id := High_Bound (Ck_Node);
9598 Null_Range : Boolean;
9599 Out_Of_Range_L : Boolean;
9600 Out_Of_Range_H : Boolean;
9603 -- Compute what is known at compile time
9605 if Known_T_LB and Known_T_HB then
9606 if Compile_Time_Known_Value (LB) then
9609 -- There's no point in checking that a bound is within its
9610 -- own range so pretend that it is known in this case. First
9611 -- deal with low bound.
9613 elsif Ekind (Etype (LB)) = E_Signed_Integer_Subtype
9614 and then Scalar_Range (Etype (LB)) = Scalar_Range (T_Typ)
9623 -- Likewise for the high bound
9625 if Compile_Time_Known_Value (HB) then
9628 elsif Ekind (Etype (HB)) = E_Signed_Integer_Subtype
9629 and then Scalar_Range (Etype (HB)) = Scalar_Range (T_Typ)
9638 -- Check for case where everything is static and we can do the
9639 -- check at compile time. This is skipped if we have an access
9640 -- type, since the access value may be null.
9642 -- ??? This code can be improved since you only need to know that
9643 -- the two respective bounds (LB & T_LB or HB & T_HB) are known at
9644 -- compile time to emit pertinent messages.
9646 if Known_T_LB and Known_T_HB and Known_LB and Known_HB
9649 -- Floating-point case
9651 if Is_Floating_Point_Type (S_Typ) then
9652 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
9654 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
9656 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
9659 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
9661 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
9663 -- Fixed or discrete type case
9666 Null_Range := Expr_Value (HB) < Expr_Value (LB);
9668 (Expr_Value (LB) < Expr_Value (T_LB))
9670 (Expr_Value (LB) > Expr_Value (T_HB));
9673 (Expr_Value (HB) > Expr_Value (T_HB))
9675 (Expr_Value (HB) < Expr_Value (T_LB));
9678 if not Null_Range then
9679 if Out_Of_Range_L then
9680 if No (Warn_Node) then
9682 (Compile_Time_Constraint_Error
9683 (Low_Bound (Ck_Node),
9684 "static value out of range of}??", T_Typ));
9688 (Compile_Time_Constraint_Error
9690 "static range out of bounds of}??", T_Typ));
9694 if Out_Of_Range_H then
9695 if No (Warn_Node) then
9697 (Compile_Time_Constraint_Error
9698 (High_Bound (Ck_Node),
9699 "static value out of range of}??", T_Typ));
9703 (Compile_Time_Constraint_Error
9705 "static range out of bounds of}??", T_Typ));
9712 LB : Node_Id := Low_Bound (Ck_Node);
9713 HB : Node_Id := High_Bound (Ck_Node);
9716 -- If either bound is a discriminant and we are within the
9717 -- record declaration, it is a use of the discriminant in a
9718 -- constraint of a component, and nothing can be checked
9719 -- here. The check will be emitted within the init proc.
9720 -- Before then, the discriminal has no real meaning.
9721 -- Similarly, if the entity is a discriminal, there is no
9722 -- check to perform yet.
9724 -- The same holds within a discriminated synchronized type,
9725 -- where the discriminant may constrain a component or an
9728 if Nkind (LB) = N_Identifier
9729 and then Denotes_Discriminant (LB, True)
9731 if Current_Scope = Scope (Entity (LB))
9732 or else Is_Concurrent_Type (Current_Scope)
9733 or else Ekind (Entity (LB)) /= E_Discriminant
9738 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
9742 if Nkind (HB) = N_Identifier
9743 and then Denotes_Discriminant (HB, True)
9745 if Current_Scope = Scope (Entity (HB))
9746 or else Is_Concurrent_Type (Current_Scope)
9747 or else Ekind (Entity (HB)) /= E_Discriminant
9752 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
9756 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
9757 Set_Paren_Count (Cond, 1);
9764 Convert_To (Base_Type (Etype (HB)),
9765 Duplicate_Subexpr_No_Checks (HB)),
9767 Convert_To (Base_Type (Etype (LB)),
9768 Duplicate_Subexpr_No_Checks (LB))),
9769 Right_Opnd => Cond);
9774 elsif Is_Scalar_Type (S_Typ) then
9776 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
9777 -- except the above simply sets a flag in the node and lets
9778 -- gigi generate the check base on the Etype of the expression.
9779 -- Sometimes, however we want to do a dynamic check against an
9780 -- arbitrary target type, so we do that here.
9782 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
9783 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9785 -- For literals, we can tell if the constraint error will be
9786 -- raised at compile time, so we never need a dynamic check, but
9787 -- if the exception will be raised, then post the usual warning,
9788 -- and replace the literal with a raise constraint error
9789 -- expression. As usual, skip this for access types
9791 elsif Compile_Time_Known_Value (Ck_Node) and then not Do_Access then
9793 LB : constant Node_Id := Type_Low_Bound (T_Typ);
9794 UB : constant Node_Id := Type_High_Bound (T_Typ);
9796 Out_Of_Range : Boolean;
9797 Static_Bounds : constant Boolean :=
9798 Compile_Time_Known_Value (LB)
9799 and Compile_Time_Known_Value (UB);
9802 -- Following range tests should use Sem_Eval routine ???
9804 if Static_Bounds then
9805 if Is_Floating_Point_Type (S_Typ) then
9807 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
9809 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
9811 -- Fixed or discrete type
9815 Expr_Value (Ck_Node) < Expr_Value (LB)
9817 Expr_Value (Ck_Node) > Expr_Value (UB);
9820 -- Bounds of the type are static and the literal is out of
9821 -- range so output a warning message.
9823 if Out_Of_Range then
9824 if No (Warn_Node) then
9826 (Compile_Time_Constraint_Error
9828 "static value out of range of}??", T_Typ));
9832 (Compile_Time_Constraint_Error
9834 "static value out of range of}??", T_Typ));
9839 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9843 -- Here for the case of a non-static expression, we need a runtime
9844 -- check unless the source type range is guaranteed to be in the
9845 -- range of the target type.
9848 if not In_Subrange_Of (S_Typ, T_Typ) then
9849 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9854 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
9855 if Is_Constrained (T_Typ) then
9857 Expr_Actual := Get_Referenced_Object (Ck_Node);
9858 Exptyp := Get_Actual_Subtype (Expr_Actual);
9860 if Is_Access_Type (Exptyp) then
9861 Exptyp := Designated_Type (Exptyp);
9864 -- String_Literal case. This needs to be handled specially be-
9865 -- cause no index types are available for string literals. The
9866 -- condition is simply:
9868 -- T_Typ'Length = string-literal-length
9870 if Nkind (Expr_Actual) = N_String_Literal then
9873 -- General array case. Here we have a usable actual subtype for
9874 -- the expression, and the condition is built from the two types
9876 -- T_Typ'First < Exptyp'First or else
9877 -- T_Typ'Last > Exptyp'Last or else
9878 -- T_Typ'First(1) < Exptyp'First(1) or else
9879 -- T_Typ'Last(1) > Exptyp'Last(1) or else
9882 elsif Is_Constrained (Exptyp) then
9884 Ndims : constant Nat := Number_Dimensions (T_Typ);
9890 L_Index := First_Index (T_Typ);
9891 R_Index := First_Index (Exptyp);
9893 for Indx in 1 .. Ndims loop
9894 if not (Nkind (L_Index) = N_Raise_Constraint_Error
9896 Nkind (R_Index) = N_Raise_Constraint_Error)
9898 -- Deal with compile time length check. Note that we
9899 -- skip this in the access case, because the access
9900 -- value may be null, so we cannot know statically.
9903 Subtypes_Statically_Match
9904 (Etype (L_Index), Etype (R_Index))
9906 -- If the target type is constrained then we
9907 -- have to check for exact equality of bounds
9908 -- (required for qualified expressions).
9910 if Is_Constrained (T_Typ) then
9913 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
9916 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
9926 -- Handle cases where we do not get a usable actual subtype that
9927 -- is constrained. This happens for example in the function call
9928 -- and explicit dereference cases. In these cases, we have to get
9929 -- the length or range from the expression itself, making sure we
9930 -- do not evaluate it more than once.
9932 -- Here Ck_Node is the original expression, or more properly the
9933 -- result of applying Duplicate_Expr to the original tree,
9934 -- forcing the result to be a name.
9938 Ndims : constant Nat := Number_Dimensions (T_Typ);
9941 -- Build the condition for the explicit dereference case
9943 for Indx in 1 .. Ndims loop
9945 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
9951 -- For a conversion to an unconstrained array type, generate an
9952 -- Action to check that the bounds of the source value are within
9953 -- the constraints imposed by the target type (RM 4.6(38)). No
9954 -- check is needed for a conversion to an access to unconstrained
9955 -- array type, as 4.6(24.15/2) requires the designated subtypes
9956 -- of the two access types to statically match.
9958 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
9959 and then not Do_Access
9962 Opnd_Index : Node_Id;
9963 Targ_Index : Node_Id;
9964 Opnd_Range : Node_Id;
9967 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
9968 Targ_Index := First_Index (T_Typ);
9969 while Present (Opnd_Index) loop
9971 -- If the index is a range, use its bounds. If it is an
9972 -- entity (as will be the case if it is a named subtype
9973 -- or an itype created for a slice) retrieve its range.
9975 if Is_Entity_Name (Opnd_Index)
9976 and then Is_Type (Entity (Opnd_Index))
9978 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
9980 Opnd_Range := Opnd_Index;
9983 if Nkind (Opnd_Range) = N_Range then
9985 (Low_Bound (Opnd_Range), Etype (Targ_Index),
9986 Assume_Valid => True)
9989 (High_Bound (Opnd_Range), Etype (Targ_Index),
9990 Assume_Valid => True)
9994 -- If null range, no check needed
9997 Compile_Time_Known_Value (High_Bound (Opnd_Range))
9999 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
10001 Expr_Value (High_Bound (Opnd_Range)) <
10002 Expr_Value (Low_Bound (Opnd_Range))
10006 elsif Is_Out_Of_Range
10007 (Low_Bound (Opnd_Range), Etype (Targ_Index),
10008 Assume_Valid => True)
10011 (High_Bound (Opnd_Range), Etype (Targ_Index),
10012 Assume_Valid => True)
10015 (Compile_Time_Constraint_Error
10016 (Wnode, "value out of range of}??", T_Typ));
10021 Discrete_Range_Cond
10022 (Opnd_Range, Etype (Targ_Index)));
10026 Next_Index (Opnd_Index);
10027 Next_Index (Targ_Index);
10034 -- Construct the test and insert into the tree
10036 if Present (Cond) then
10038 Cond := Guard_Access (Cond, Loc, Ck_Node);
10042 (Make_Raise_Constraint_Error (Loc,
10044 Reason => CE_Range_Check_Failed));
10048 end Selected_Range_Checks;
10050 -------------------------------
10051 -- Storage_Checks_Suppressed --
10052 -------------------------------
10054 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
10056 if Present (E) and then Checks_May_Be_Suppressed (E) then
10057 return Is_Check_Suppressed (E, Storage_Check);
10059 return Scope_Suppress.Suppress (Storage_Check);
10061 end Storage_Checks_Suppressed;
10063 ---------------------------
10064 -- Tag_Checks_Suppressed --
10065 ---------------------------
10067 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
10070 and then Checks_May_Be_Suppressed (E)
10072 return Is_Check_Suppressed (E, Tag_Check);
10074 return Scope_Suppress.Suppress (Tag_Check);
10076 end Tag_Checks_Suppressed;
10078 ---------------------------------------
10079 -- Validate_Alignment_Check_Warnings --
10080 ---------------------------------------
10082 procedure Validate_Alignment_Check_Warnings is
10084 for J in Alignment_Warnings.First .. Alignment_Warnings.Last loop
10086 AWR : Alignment_Warnings_Record
10087 renames Alignment_Warnings.Table (J);
10089 if Known_Alignment (AWR.E)
10090 and then AWR.A mod Alignment (AWR.E) = 0
10092 Delete_Warning_And_Continuations (AWR.W);
10096 end Validate_Alignment_Check_Warnings;
10098 --------------------------
10099 -- Validity_Check_Range --
10100 --------------------------
10102 procedure Validity_Check_Range (N : Node_Id) is
10104 if Validity_Checks_On and Validity_Check_Operands then
10105 if Nkind (N) = N_Range then
10106 Ensure_Valid (Low_Bound (N));
10107 Ensure_Valid (High_Bound (N));
10110 end Validity_Check_Range;
10112 --------------------------------
10113 -- Validity_Checks_Suppressed --
10114 --------------------------------
10116 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
10118 if Present (E) and then Checks_May_Be_Suppressed (E) then
10119 return Is_Check_Suppressed (E, Validity_Check);
10121 return Scope_Suppress.Suppress (Validity_Check);
10123 end Validity_Checks_Suppressed;