1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2016, 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
391 Typ : constant Entity_Id := Etype (N);
394 -- Floating-point case. If Etype is not set (this can happen when we
395 -- activate a check on a node that has not yet been analyzed), then
396 -- we assume we do not have a floating-point type (as per our spec).
398 if Present (Typ) and then Is_Floating_Point_Type (Typ) then
400 -- Ignore call if we have no automatic overflow checks on the target
401 -- and Check_Float_Overflow mode is not set. These are the cases in
402 -- which we expect to generate infinities and NaN's with no check.
404 if not (Machine_Overflows_On_Target or Check_Float_Overflow) then
407 -- Ignore for unary operations ("+", "-", abs) since these can never
408 -- result in overflow for floating-point cases.
410 elsif Nkind (N) in N_Unary_Op then
413 -- Otherwise we will set the flag
422 -- Nothing to do for Rem/Mod/Plus (overflow not possible, the check
423 -- for zero-divide is a divide check, not an overflow check).
425 if Nkind_In (N, N_Op_Rem, N_Op_Mod, N_Op_Plus) then
430 -- Fall through for cases where we do set the flag
432 Set_Do_Overflow_Check (N, True);
433 Possible_Local_Raise (N, Standard_Constraint_Error);
434 end Activate_Overflow_Check;
436 --------------------------
437 -- Activate_Range_Check --
438 --------------------------
440 procedure Activate_Range_Check (N : Node_Id) is
442 Set_Do_Range_Check (N, True);
443 Possible_Local_Raise (N, Standard_Constraint_Error);
444 end Activate_Range_Check;
446 ---------------------------------
447 -- Alignment_Checks_Suppressed --
448 ---------------------------------
450 function Alignment_Checks_Suppressed (E : Entity_Id) return Boolean is
452 if Present (E) and then Checks_May_Be_Suppressed (E) then
453 return Is_Check_Suppressed (E, Alignment_Check);
455 return Scope_Suppress.Suppress (Alignment_Check);
457 end Alignment_Checks_Suppressed;
459 ----------------------------------
460 -- Allocation_Checks_Suppressed --
461 ----------------------------------
463 -- Note: at the current time there are no calls to this function, because
464 -- the relevant check is in the run-time, so it is not a check that the
465 -- compiler can suppress anyway, but we still have to recognize the check
466 -- name Allocation_Check since it is part of the standard.
468 function Allocation_Checks_Suppressed (E : Entity_Id) return Boolean is
470 if Present (E) and then Checks_May_Be_Suppressed (E) then
471 return Is_Check_Suppressed (E, Allocation_Check);
473 return Scope_Suppress.Suppress (Allocation_Check);
475 end Allocation_Checks_Suppressed;
477 -------------------------
478 -- Append_Range_Checks --
479 -------------------------
481 procedure Append_Range_Checks
482 (Checks : Check_Result;
484 Suppress_Typ : Entity_Id;
485 Static_Sloc : Source_Ptr;
488 Internal_Flag_Node : constant Node_Id := Flag_Node;
489 Internal_Static_Sloc : constant Source_Ptr := Static_Sloc;
491 Checks_On : constant Boolean :=
492 (not Index_Checks_Suppressed (Suppress_Typ))
493 or else (not Range_Checks_Suppressed (Suppress_Typ));
496 -- For now we just return if Checks_On is false, however this should
497 -- be enhanced to check for an always True value in the condition
498 -- and to generate a compilation warning???
500 if not Checks_On then
505 exit when No (Checks (J));
507 if Nkind (Checks (J)) = N_Raise_Constraint_Error
508 and then Present (Condition (Checks (J)))
510 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
511 Append_To (Stmts, Checks (J));
512 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
518 Make_Raise_Constraint_Error (Internal_Static_Sloc,
519 Reason => CE_Range_Check_Failed));
522 end Append_Range_Checks;
524 ------------------------
525 -- Apply_Access_Check --
526 ------------------------
528 procedure Apply_Access_Check (N : Node_Id) is
529 P : constant Node_Id := Prefix (N);
532 -- We do not need checks if we are not generating code (i.e. the
533 -- expander is not active). This is not just an optimization, there
534 -- are cases (e.g. with pragma Debug) where generating the checks
535 -- can cause real trouble).
537 if not Expander_Active then
541 -- No check if short circuiting makes check unnecessary
543 if not Check_Needed (P, Access_Check) then
547 -- No check if accessing the Offset_To_Top component of a dispatch
548 -- table. They are safe by construction.
550 if Tagged_Type_Expansion
551 and then Present (Etype (P))
552 and then RTU_Loaded (Ada_Tags)
553 and then RTE_Available (RE_Offset_To_Top_Ptr)
554 and then Etype (P) = RTE (RE_Offset_To_Top_Ptr)
559 -- Otherwise go ahead and install the check
561 Install_Null_Excluding_Check (P);
562 end Apply_Access_Check;
564 -------------------------------
565 -- Apply_Accessibility_Check --
566 -------------------------------
568 procedure Apply_Accessibility_Check
571 Insert_Node : Node_Id)
573 Loc : constant Source_Ptr := Sloc (N);
574 Param_Ent : Entity_Id := Param_Entity (N);
575 Param_Level : Node_Id;
576 Type_Level : Node_Id;
579 if Ada_Version >= Ada_2012
580 and then not Present (Param_Ent)
581 and then Is_Entity_Name (N)
582 and then Ekind_In (Entity (N), E_Constant, E_Variable)
583 and then Present (Effective_Extra_Accessibility (Entity (N)))
585 Param_Ent := Entity (N);
586 while Present (Renamed_Object (Param_Ent)) loop
588 -- Renamed_Object must return an Entity_Name here
589 -- because of preceding "Present (E_E_A (...))" test.
591 Param_Ent := Entity (Renamed_Object (Param_Ent));
595 if Inside_A_Generic then
598 -- Only apply the run-time check if the access parameter has an
599 -- associated extra access level parameter and when the level of the
600 -- type is less deep than the level of the access parameter, and
601 -- accessibility checks are not suppressed.
603 elsif Present (Param_Ent)
604 and then Present (Extra_Accessibility (Param_Ent))
605 and then UI_Gt (Object_Access_Level (N),
606 Deepest_Type_Access_Level (Typ))
607 and then not Accessibility_Checks_Suppressed (Param_Ent)
608 and then not Accessibility_Checks_Suppressed (Typ)
611 New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc);
614 Make_Integer_Literal (Loc, Deepest_Type_Access_Level (Typ));
616 -- Raise Program_Error if the accessibility level of the access
617 -- parameter is deeper than the level of the target access type.
619 Insert_Action (Insert_Node,
620 Make_Raise_Program_Error (Loc,
623 Left_Opnd => Param_Level,
624 Right_Opnd => Type_Level),
625 Reason => PE_Accessibility_Check_Failed));
627 Analyze_And_Resolve (N);
629 end Apply_Accessibility_Check;
631 --------------------------------
632 -- Apply_Address_Clause_Check --
633 --------------------------------
635 procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is
636 pragma Assert (Nkind (N) = N_Freeze_Entity);
638 AC : constant Node_Id := Address_Clause (E);
639 Loc : constant Source_Ptr := Sloc (AC);
640 Typ : constant Entity_Id := Etype (E);
643 -- Address expression (not necessarily the same as Aexp, for example
644 -- when Aexp is a reference to a constant, in which case Expr gets
645 -- reset to reference the value expression of the constant).
648 -- See if alignment check needed. Note that we never need a check if the
649 -- maximum alignment is one, since the check will always succeed.
651 -- Note: we do not check for checks suppressed here, since that check
652 -- was done in Sem_Ch13 when the address clause was processed. We are
653 -- only called if checks were not suppressed. The reason for this is
654 -- that we have to delay the call to Apply_Alignment_Check till freeze
655 -- time (so that all types etc are elaborated), but we have to check
656 -- the status of check suppressing at the point of the address clause.
659 or else not Check_Address_Alignment (AC)
660 or else Maximum_Alignment = 1
665 -- Obtain expression from address clause
667 Expr := Address_Value (Expression (AC));
669 -- See if we know that Expr has an acceptable value at compile time. If
670 -- it hasn't or we don't know, we defer issuing the warning until the
671 -- end of the compilation to take into account back end annotations.
673 if Compile_Time_Known_Value (Expr)
674 and then (Known_Alignment (E) or else Known_Alignment (Typ))
677 AL : Uint := Alignment (Typ);
680 -- The object alignment might be more restrictive than the type
683 if Known_Alignment (E) then
687 if Expr_Value (Expr) mod AL = 0 then
692 -- If the expression has the form X'Address, then we can find out if the
693 -- object X has an alignment that is compatible with the object E. If it
694 -- hasn't or we don't know, we defer issuing the warning until the end
695 -- of the compilation to take into account back end annotations.
697 elsif Nkind (Expr) = N_Attribute_Reference
698 and then Attribute_Name (Expr) = Name_Address
700 Has_Compatible_Alignment (E, Prefix (Expr), False) = Known_Compatible
705 -- Here we do not know if the value is acceptable. Strictly we don't
706 -- have to do anything, since if the alignment is bad, we have an
707 -- erroneous program. However we are allowed to check for erroneous
708 -- conditions and we decide to do this by default if the check is not
711 -- However, don't do the check if elaboration code is unwanted
713 if Restriction_Active (No_Elaboration_Code) then
716 -- Generate a check to raise PE if alignment may be inappropriate
719 -- If the original expression is a non-static constant, use the name
720 -- of the constant itself rather than duplicating its initialization
721 -- expression, which was extracted above.
723 -- Note: Expr is empty if the address-clause is applied to in-mode
724 -- actuals (allowed by 13.1(22)).
726 if not Present (Expr)
728 (Is_Entity_Name (Expression (AC))
729 and then Ekind (Entity (Expression (AC))) = E_Constant
730 and then Nkind (Parent (Entity (Expression (AC)))) =
731 N_Object_Declaration)
733 Expr := New_Copy_Tree (Expression (AC));
735 Remove_Side_Effects (Expr);
738 if No (Actions (N)) then
739 Set_Actions (N, New_List);
742 Prepend_To (Actions (N),
743 Make_Raise_Program_Error (Loc,
750 (RTE (RE_Integer_Address), Expr),
752 Make_Attribute_Reference (Loc,
753 Prefix => New_Occurrence_Of (E, Loc),
754 Attribute_Name => Name_Alignment)),
755 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
756 Reason => PE_Misaligned_Address_Value));
758 Warning_Msg := No_Error_Msg;
759 Analyze (First (Actions (N)), Suppress => All_Checks);
761 -- If the above raise action generated a warning message (for example
762 -- from Warn_On_Non_Local_Exception mode with the active restriction
763 -- No_Exception_Propagation).
765 if Warning_Msg /= No_Error_Msg then
767 -- If the expression has a known at compile time value, then
768 -- once we know the alignment of the type, we can check if the
769 -- exception will be raised or not, and if not, we don't need
770 -- the warning so we will kill the warning later on.
772 if Compile_Time_Known_Value (Expr) then
773 Alignment_Warnings.Append
774 ((E => E, A => Expr_Value (Expr), W => Warning_Msg));
776 -- Add explanation of the warning generated by the check
780 ("\address value may be incompatible with alignment of "
790 -- If we have some missing run time component in configurable run time
791 -- mode then just skip the check (it is not required in any case).
793 when RE_Not_Available =>
795 end Apply_Address_Clause_Check;
797 -------------------------------------
798 -- Apply_Arithmetic_Overflow_Check --
799 -------------------------------------
801 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
803 -- Use old routine in almost all cases (the only case we are treating
804 -- specially is the case of a signed integer arithmetic op with the
805 -- overflow checking mode set to MINIMIZED or ELIMINATED).
807 if Overflow_Check_Mode = Strict
808 or else not Is_Signed_Integer_Arithmetic_Op (N)
810 Apply_Arithmetic_Overflow_Strict (N);
812 -- Otherwise use the new routine for the case of a signed integer
813 -- arithmetic op, with Do_Overflow_Check set to True, and the checking
814 -- mode is MINIMIZED or ELIMINATED.
817 Apply_Arithmetic_Overflow_Minimized_Eliminated (N);
819 end Apply_Arithmetic_Overflow_Check;
821 --------------------------------------
822 -- Apply_Arithmetic_Overflow_Strict --
823 --------------------------------------
825 -- This routine is called only if the type is an integer type, and a
826 -- software arithmetic overflow check may be needed for op (add, subtract,
827 -- or multiply). This check is performed only if Software_Overflow_Checking
828 -- is enabled and Do_Overflow_Check is set. In this case we expand the
829 -- operation into a more complex sequence of tests that ensures that
830 -- overflow is properly caught.
832 -- This is used in CHECKED modes. It is identical to the code for this
833 -- cases before the big overflow earthquake, thus ensuring that in this
834 -- modes we have compatible behavior (and reliability) to what was there
835 -- before. It is also called for types other than signed integers, and if
836 -- the Do_Overflow_Check flag is off.
838 -- Note: we also call this routine if we decide in the MINIMIZED case
839 -- to give up and just generate an overflow check without any fuss.
841 procedure Apply_Arithmetic_Overflow_Strict (N : Node_Id) is
842 Loc : constant Source_Ptr := Sloc (N);
843 Typ : constant Entity_Id := Etype (N);
844 Rtyp : constant Entity_Id := Root_Type (Typ);
847 -- Nothing to do if Do_Overflow_Check not set or overflow checks
850 if not Do_Overflow_Check (N) then
854 -- An interesting special case. If the arithmetic operation appears as
855 -- the operand of a type conversion:
859 -- and all the following conditions apply:
861 -- arithmetic operation is for a signed integer type
862 -- target type type1 is a static integer subtype
863 -- range of x and y are both included in the range of type1
864 -- range of x op y is included in the range of type1
865 -- size of type1 is at least twice the result size of op
867 -- then we don't do an overflow check in any case. Instead, we transform
868 -- the operation so that we end up with:
870 -- type1 (type1 (x) op type1 (y))
872 -- This avoids intermediate overflow before the conversion. It is
873 -- explicitly permitted by RM 3.5.4(24):
875 -- For the execution of a predefined operation of a signed integer
876 -- type, the implementation need not raise Constraint_Error if the
877 -- result is outside the base range of the type, so long as the
878 -- correct result is produced.
880 -- It's hard to imagine that any programmer counts on the exception
881 -- being raised in this case, and in any case it's wrong coding to
882 -- have this expectation, given the RM permission. Furthermore, other
883 -- Ada compilers do allow such out of range results.
885 -- Note that we do this transformation even if overflow checking is
886 -- off, since this is precisely about giving the "right" result and
887 -- avoiding the need for an overflow check.
889 -- Note: this circuit is partially redundant with respect to the similar
890 -- processing in Exp_Ch4.Expand_N_Type_Conversion, but the latter deals
891 -- with cases that do not come through here. We still need the following
892 -- processing even with the Exp_Ch4 code in place, since we want to be
893 -- sure not to generate the arithmetic overflow check in these cases
894 -- (Exp_Ch4 would have a hard time removing them once generated).
896 if Is_Signed_Integer_Type (Typ)
897 and then Nkind (Parent (N)) = N_Type_Conversion
899 Conversion_Optimization : declare
900 Target_Type : constant Entity_Id :=
901 Base_Type (Entity (Subtype_Mark (Parent (N))));
915 if Is_Integer_Type (Target_Type)
916 and then RM_Size (Root_Type (Target_Type)) >= 2 * RM_Size (Rtyp)
918 Tlo := Expr_Value (Type_Low_Bound (Target_Type));
919 Thi := Expr_Value (Type_High_Bound (Target_Type));
922 (Left_Opnd (N), LOK, Llo, Lhi, Assume_Valid => True);
924 (Right_Opnd (N), ROK, Rlo, Rhi, Assume_Valid => True);
927 and then Tlo <= Llo and then Lhi <= Thi
928 and then Tlo <= Rlo and then Rhi <= Thi
930 Determine_Range (N, VOK, Vlo, Vhi, Assume_Valid => True);
932 if VOK and then Tlo <= Vlo and then Vhi <= Thi then
933 Rewrite (Left_Opnd (N),
934 Make_Type_Conversion (Loc,
935 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
936 Expression => Relocate_Node (Left_Opnd (N))));
938 Rewrite (Right_Opnd (N),
939 Make_Type_Conversion (Loc,
940 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
941 Expression => Relocate_Node (Right_Opnd (N))));
943 -- Rewrite the conversion operand so that the original
944 -- node is retained, in order to avoid the warning for
945 -- redundant conversions in Resolve_Type_Conversion.
947 Rewrite (N, Relocate_Node (N));
949 Set_Etype (N, Target_Type);
951 Analyze_And_Resolve (Left_Opnd (N), Target_Type);
952 Analyze_And_Resolve (Right_Opnd (N), Target_Type);
954 -- Given that the target type is twice the size of the
955 -- source type, overflow is now impossible, so we can
956 -- safely kill the overflow check and return.
958 Set_Do_Overflow_Check (N, False);
963 end Conversion_Optimization;
966 -- Now see if an overflow check is required
969 Siz : constant Int := UI_To_Int (Esize (Rtyp));
970 Dsiz : constant Int := Siz * 2;
977 -- Skip check if back end does overflow checks, or the overflow flag
978 -- is not set anyway, or we are not doing code expansion, or the
979 -- parent node is a type conversion whose operand is an arithmetic
980 -- operation on signed integers on which the expander can promote
981 -- later the operands to type Integer (see Expand_N_Type_Conversion).
983 if Backend_Overflow_Checks_On_Target
984 or else not Do_Overflow_Check (N)
985 or else not Expander_Active
986 or else (Present (Parent (N))
987 and then Nkind (Parent (N)) = N_Type_Conversion
988 and then Integer_Promotion_Possible (Parent (N)))
993 -- Otherwise, generate the full general code for front end overflow
994 -- detection, which works by doing arithmetic in a larger type:
1000 -- Typ (Checktyp (x) op Checktyp (y));
1002 -- where Typ is the type of the original expression, and Checktyp is
1003 -- an integer type of sufficient length to hold the largest possible
1006 -- If the size of check type exceeds the size of Long_Long_Integer,
1007 -- we use a different approach, expanding to:
1009 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
1011 -- where xxx is Add, Multiply or Subtract as appropriate
1013 -- Find check type if one exists
1015 if Dsiz <= Standard_Integer_Size then
1016 Ctyp := Standard_Integer;
1018 elsif Dsiz <= Standard_Long_Long_Integer_Size then
1019 Ctyp := Standard_Long_Long_Integer;
1021 -- No check type exists, use runtime call
1024 if Nkind (N) = N_Op_Add then
1025 Cent := RE_Add_With_Ovflo_Check;
1027 elsif Nkind (N) = N_Op_Multiply then
1028 Cent := RE_Multiply_With_Ovflo_Check;
1031 pragma Assert (Nkind (N) = N_Op_Subtract);
1032 Cent := RE_Subtract_With_Ovflo_Check;
1037 Make_Function_Call (Loc,
1038 Name => New_Occurrence_Of (RTE (Cent), Loc),
1039 Parameter_Associations => New_List (
1040 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
1041 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
1043 Analyze_And_Resolve (N, Typ);
1047 -- If we fall through, we have the case where we do the arithmetic
1048 -- in the next higher type and get the check by conversion. In these
1049 -- cases Ctyp is set to the type to be used as the check type.
1051 Opnod := Relocate_Node (N);
1053 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
1056 Set_Etype (Opnd, Ctyp);
1057 Set_Analyzed (Opnd, True);
1058 Set_Left_Opnd (Opnod, Opnd);
1060 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
1063 Set_Etype (Opnd, Ctyp);
1064 Set_Analyzed (Opnd, True);
1065 Set_Right_Opnd (Opnod, Opnd);
1067 -- The type of the operation changes to the base type of the check
1068 -- type, and we reset the overflow check indication, since clearly no
1069 -- overflow is possible now that we are using a double length type.
1070 -- We also set the Analyzed flag to avoid a recursive attempt to
1073 Set_Etype (Opnod, Base_Type (Ctyp));
1074 Set_Do_Overflow_Check (Opnod, False);
1075 Set_Analyzed (Opnod, True);
1077 -- Now build the outer conversion
1079 Opnd := OK_Convert_To (Typ, Opnod);
1081 Set_Etype (Opnd, Typ);
1083 -- In the discrete type case, we directly generate the range check
1084 -- for the outer operand. This range check will implement the
1085 -- required overflow check.
1087 if Is_Discrete_Type (Typ) then
1089 Generate_Range_Check
1090 (Expression (N), Typ, CE_Overflow_Check_Failed);
1092 -- For other types, we enable overflow checking on the conversion,
1093 -- after setting the node as analyzed to prevent recursive attempts
1094 -- to expand the conversion node.
1097 Set_Analyzed (Opnd, True);
1098 Enable_Overflow_Check (Opnd);
1103 when RE_Not_Available =>
1106 end Apply_Arithmetic_Overflow_Strict;
1108 ----------------------------------------------------
1109 -- Apply_Arithmetic_Overflow_Minimized_Eliminated --
1110 ----------------------------------------------------
1112 procedure Apply_Arithmetic_Overflow_Minimized_Eliminated (Op : Node_Id) is
1113 pragma Assert (Is_Signed_Integer_Arithmetic_Op (Op));
1115 Loc : constant Source_Ptr := Sloc (Op);
1116 P : constant Node_Id := Parent (Op);
1118 LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer);
1119 -- Operands and results are of this type when we convert
1121 Result_Type : constant Entity_Id := Etype (Op);
1122 -- Original result type
1124 Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
1125 pragma Assert (Check_Mode in Minimized_Or_Eliminated);
1128 -- Ranges of values for result
1131 -- Nothing to do if our parent is one of the following:
1133 -- Another signed integer arithmetic op
1134 -- A membership operation
1135 -- A comparison operation
1137 -- In all these cases, we will process at the higher level (and then
1138 -- this node will be processed during the downwards recursion that
1139 -- is part of the processing in Minimize_Eliminate_Overflows).
1141 if Is_Signed_Integer_Arithmetic_Op (P)
1142 or else Nkind (P) in N_Membership_Test
1143 or else Nkind (P) in N_Op_Compare
1145 -- This is also true for an alternative in a case expression
1147 or else Nkind (P) = N_Case_Expression_Alternative
1149 -- This is also true for a range operand in a membership test
1151 or else (Nkind (P) = N_Range
1152 and then Nkind (Parent (P)) in N_Membership_Test)
1154 -- If_Expressions and Case_Expressions are treated as arithmetic
1155 -- ops, but if they appear in an assignment or similar contexts
1156 -- there is no overflow check that starts from that parent node,
1157 -- so apply check now.
1159 if Nkind_In (P, N_If_Expression, N_Case_Expression)
1160 and then not Is_Signed_Integer_Arithmetic_Op (Parent (P))
1168 -- Otherwise, we have a top level arithmetic operation node, and this
1169 -- is where we commence the special processing for MINIMIZED/ELIMINATED
1170 -- modes. This is the case where we tell the machinery not to move into
1171 -- Bignum mode at this top level (of course the top level operation
1172 -- will still be in Bignum mode if either of its operands are of type
1175 Minimize_Eliminate_Overflows (Op, Lo, Hi, Top_Level => True);
1177 -- That call may but does not necessarily change the result type of Op.
1178 -- It is the job of this routine to undo such changes, so that at the
1179 -- top level, we have the proper type. This "undoing" is a point at
1180 -- which a final overflow check may be applied.
1182 -- If the result type was not fiddled we are all set. We go to base
1183 -- types here because things may have been rewritten to generate the
1184 -- base type of the operand types.
1186 if Base_Type (Etype (Op)) = Base_Type (Result_Type) then
1191 elsif Is_RTE (Etype (Op), RE_Bignum) then
1193 -- We need a sequence that looks like:
1195 -- Rnn : Result_Type;
1198 -- M : Mark_Id := SS_Mark;
1200 -- Rnn := Long_Long_Integer'Base (From_Bignum (Op));
1204 -- This block is inserted (using Insert_Actions), and then the node
1205 -- is replaced with a reference to Rnn.
1207 -- If our parent is a conversion node then there is no point in
1208 -- generating a conversion to Result_Type. Instead, we let the parent
1209 -- handle this. Note that this special case is not just about
1210 -- optimization. Consider
1214 -- X := Long_Long_Integer'Base (A * (B ** C));
1216 -- Now the product may fit in Long_Long_Integer but not in Integer.
1217 -- In MINIMIZED/ELIMINATED mode, we don't want to introduce an
1218 -- overflow exception for this intermediate value.
1221 Blk : constant Node_Id := Make_Bignum_Block (Loc);
1222 Rnn : constant Entity_Id := Make_Temporary (Loc, 'R', Op);
1228 RHS := Convert_From_Bignum (Op);
1230 if Nkind (P) /= N_Type_Conversion then
1231 Convert_To_And_Rewrite (Result_Type, RHS);
1232 Rtype := Result_Type;
1234 -- Interesting question, do we need a check on that conversion
1235 -- operation. Answer, not if we know the result is in range.
1236 -- At the moment we are not taking advantage of this. To be
1237 -- looked at later ???
1244 (First (Statements (Handled_Statement_Sequence (Blk))),
1245 Make_Assignment_Statement (Loc,
1246 Name => New_Occurrence_Of (Rnn, Loc),
1247 Expression => RHS));
1249 Insert_Actions (Op, New_List (
1250 Make_Object_Declaration (Loc,
1251 Defining_Identifier => Rnn,
1252 Object_Definition => New_Occurrence_Of (Rtype, Loc)),
1255 Rewrite (Op, New_Occurrence_Of (Rnn, Loc));
1256 Analyze_And_Resolve (Op);
1259 -- Here we know the result is Long_Long_Integer'Base, or that it has
1260 -- been rewritten because the parent operation is a conversion. See
1261 -- Apply_Arithmetic_Overflow_Strict.Conversion_Optimization.
1265 (Etype (Op) = LLIB or else Nkind (Parent (Op)) = N_Type_Conversion);
1267 -- All we need to do here is to convert the result to the proper
1268 -- result type. As explained above for the Bignum case, we can
1269 -- omit this if our parent is a type conversion.
1271 if Nkind (P) /= N_Type_Conversion then
1272 Convert_To_And_Rewrite (Result_Type, Op);
1275 Analyze_And_Resolve (Op);
1277 end Apply_Arithmetic_Overflow_Minimized_Eliminated;
1279 ----------------------------
1280 -- Apply_Constraint_Check --
1281 ----------------------------
1283 procedure Apply_Constraint_Check
1286 No_Sliding : Boolean := False)
1288 Desig_Typ : Entity_Id;
1291 -- No checks inside a generic (check the instantiations)
1293 if Inside_A_Generic then
1297 -- Apply required constraint checks
1299 if Is_Scalar_Type (Typ) then
1300 Apply_Scalar_Range_Check (N, Typ);
1302 elsif Is_Array_Type (Typ) then
1304 -- A useful optimization: an aggregate with only an others clause
1305 -- always has the right bounds.
1307 if Nkind (N) = N_Aggregate
1308 and then No (Expressions (N))
1310 (First (Choices (First (Component_Associations (N)))))
1316 if Is_Constrained (Typ) then
1317 Apply_Length_Check (N, Typ);
1320 Apply_Range_Check (N, Typ);
1323 Apply_Range_Check (N, Typ);
1326 elsif (Is_Record_Type (Typ) or else Is_Private_Type (Typ))
1327 and then Has_Discriminants (Base_Type (Typ))
1328 and then Is_Constrained (Typ)
1330 Apply_Discriminant_Check (N, Typ);
1332 elsif Is_Access_Type (Typ) then
1334 Desig_Typ := Designated_Type (Typ);
1336 -- No checks necessary if expression statically null
1338 if Known_Null (N) then
1339 if Can_Never_Be_Null (Typ) then
1340 Install_Null_Excluding_Check (N);
1343 -- No sliding possible on access to arrays
1345 elsif Is_Array_Type (Desig_Typ) then
1346 if Is_Constrained (Desig_Typ) then
1347 Apply_Length_Check (N, Typ);
1350 Apply_Range_Check (N, Typ);
1352 elsif Has_Discriminants (Base_Type (Desig_Typ))
1353 and then Is_Constrained (Desig_Typ)
1355 Apply_Discriminant_Check (N, Typ);
1358 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1359 -- this check if the constraint node is illegal, as shown by having
1360 -- an error posted. This additional guard prevents cascaded errors
1361 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1363 if Can_Never_Be_Null (Typ)
1364 and then not Can_Never_Be_Null (Etype (N))
1365 and then not Error_Posted (N)
1367 Install_Null_Excluding_Check (N);
1370 end Apply_Constraint_Check;
1372 ------------------------------
1373 -- Apply_Discriminant_Check --
1374 ------------------------------
1376 procedure Apply_Discriminant_Check
1379 Lhs : Node_Id := Empty)
1381 Loc : constant Source_Ptr := Sloc (N);
1382 Do_Access : constant Boolean := Is_Access_Type (Typ);
1383 S_Typ : Entity_Id := Etype (N);
1387 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean;
1388 -- A heap object with an indefinite subtype is constrained by its
1389 -- initial value, and assigning to it requires a constraint_check.
1390 -- The target may be an explicit dereference, or a renaming of one.
1392 function Is_Aliased_Unconstrained_Component return Boolean;
1393 -- It is possible for an aliased component to have a nominal
1394 -- unconstrained subtype (through instantiation). If this is a
1395 -- discriminated component assigned in the expansion of an aggregate
1396 -- in an initialization, the check must be suppressed. This unusual
1397 -- situation requires a predicate of its own.
1399 ----------------------------------
1400 -- Denotes_Explicit_Dereference --
1401 ----------------------------------
1403 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean is
1406 Nkind (Obj) = N_Explicit_Dereference
1408 (Is_Entity_Name (Obj)
1409 and then Present (Renamed_Object (Entity (Obj)))
1410 and then Nkind (Renamed_Object (Entity (Obj))) =
1411 N_Explicit_Dereference);
1412 end Denotes_Explicit_Dereference;
1414 ----------------------------------------
1415 -- Is_Aliased_Unconstrained_Component --
1416 ----------------------------------------
1418 function Is_Aliased_Unconstrained_Component return Boolean is
1423 if Nkind (Lhs) /= N_Selected_Component then
1426 Comp := Entity (Selector_Name (Lhs));
1427 Pref := Prefix (Lhs);
1430 if Ekind (Comp) /= E_Component
1431 or else not Is_Aliased (Comp)
1436 return not Comes_From_Source (Pref)
1437 and then In_Instance
1438 and then not Is_Constrained (Etype (Comp));
1439 end Is_Aliased_Unconstrained_Component;
1441 -- Start of processing for Apply_Discriminant_Check
1445 T_Typ := Designated_Type (Typ);
1450 -- Nothing to do if discriminant checks are suppressed or else no code
1451 -- is to be generated
1453 if not Expander_Active
1454 or else Discriminant_Checks_Suppressed (T_Typ)
1459 -- No discriminant checks necessary for an access when expression is
1460 -- statically Null. This is not only an optimization, it is fundamental
1461 -- because otherwise discriminant checks may be generated in init procs
1462 -- for types containing an access to a not-yet-frozen record, causing a
1463 -- deadly forward reference.
1465 -- Also, if the expression is of an access type whose designated type is
1466 -- incomplete, then the access value must be null and we suppress the
1469 if Known_Null (N) then
1472 elsif Is_Access_Type (S_Typ) then
1473 S_Typ := Designated_Type (S_Typ);
1475 if Ekind (S_Typ) = E_Incomplete_Type then
1480 -- If an assignment target is present, then we need to generate the
1481 -- actual subtype if the target is a parameter or aliased object with
1482 -- an unconstrained nominal subtype.
1484 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1485 -- subtype to the parameter and dereference cases, since other aliased
1486 -- objects are unconstrained (unless the nominal subtype is explicitly
1490 and then (Present (Param_Entity (Lhs))
1491 or else (Ada_Version < Ada_2005
1492 and then not Is_Constrained (T_Typ)
1493 and then Is_Aliased_View (Lhs)
1494 and then not Is_Aliased_Unconstrained_Component)
1495 or else (Ada_Version >= Ada_2005
1496 and then not Is_Constrained (T_Typ)
1497 and then Denotes_Explicit_Dereference (Lhs)
1498 and then Nkind (Original_Node (Lhs)) /=
1501 T_Typ := Get_Actual_Subtype (Lhs);
1504 -- Nothing to do if the type is unconstrained (this is the case where
1505 -- the actual subtype in the RM sense of N is unconstrained and no check
1508 if not Is_Constrained (T_Typ) then
1511 -- Ada 2005: nothing to do if the type is one for which there is a
1512 -- partial view that is constrained.
1514 elsif Ada_Version >= Ada_2005
1515 and then Object_Type_Has_Constrained_Partial_View
1516 (Typ => Base_Type (T_Typ),
1517 Scop => Current_Scope)
1522 -- Nothing to do if the type is an Unchecked_Union
1524 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1528 -- Suppress checks if the subtypes are the same. The check must be
1529 -- preserved in an assignment to a formal, because the constraint is
1530 -- given by the actual.
1532 if Nkind (Original_Node (N)) /= N_Allocator
1534 or else not Is_Entity_Name (Lhs)
1535 or else No (Param_Entity (Lhs)))
1538 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1539 and then not Is_Aliased_View (Lhs)
1544 -- We can also eliminate checks on allocators with a subtype mark that
1545 -- coincides with the context type. The context type may be a subtype
1546 -- without a constraint (common case, a generic actual).
1548 elsif Nkind (Original_Node (N)) = N_Allocator
1549 and then Is_Entity_Name (Expression (Original_Node (N)))
1552 Alloc_Typ : constant Entity_Id :=
1553 Entity (Expression (Original_Node (N)));
1556 if Alloc_Typ = T_Typ
1557 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1558 and then Is_Entity_Name (
1559 Subtype_Indication (Parent (T_Typ)))
1560 and then Alloc_Typ = Base_Type (T_Typ))
1568 -- See if we have a case where the types are both constrained, and all
1569 -- the constraints are constants. In this case, we can do the check
1570 -- successfully at compile time.
1572 -- We skip this check for the case where the node is rewritten as
1573 -- an allocator, because it already carries the context subtype,
1574 -- and extracting the discriminants from the aggregate is messy.
1576 if Is_Constrained (S_Typ)
1577 and then Nkind (Original_Node (N)) /= N_Allocator
1587 -- S_Typ may not have discriminants in the case where it is a
1588 -- private type completed by a default discriminated type. In that
1589 -- case, we need to get the constraints from the underlying type.
1590 -- If the underlying type is unconstrained (i.e. has no default
1591 -- discriminants) no check is needed.
1593 if Has_Discriminants (S_Typ) then
1594 Discr := First_Discriminant (S_Typ);
1595 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1598 Discr := First_Discriminant (Underlying_Type (S_Typ));
1601 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1607 -- A further optimization: if T_Typ is derived from S_Typ
1608 -- without imposing a constraint, no check is needed.
1610 if Nkind (Original_Node (Parent (T_Typ))) =
1611 N_Full_Type_Declaration
1614 Type_Def : constant Node_Id :=
1615 Type_Definition (Original_Node (Parent (T_Typ)));
1617 if Nkind (Type_Def) = N_Derived_Type_Definition
1618 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1619 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1627 -- Constraint may appear in full view of type
1629 if Ekind (T_Typ) = E_Private_Subtype
1630 and then Present (Full_View (T_Typ))
1633 First_Elmt (Discriminant_Constraint (Full_View (T_Typ)));
1636 First_Elmt (Discriminant_Constraint (T_Typ));
1639 while Present (Discr) loop
1640 ItemS := Node (DconS);
1641 ItemT := Node (DconT);
1643 -- For a discriminated component type constrained by the
1644 -- current instance of an enclosing type, there is no
1645 -- applicable discriminant check.
1647 if Nkind (ItemT) = N_Attribute_Reference
1648 and then Is_Access_Type (Etype (ItemT))
1649 and then Is_Entity_Name (Prefix (ItemT))
1650 and then Is_Type (Entity (Prefix (ItemT)))
1655 -- If the expressions for the discriminants are identical
1656 -- and it is side-effect free (for now just an entity),
1657 -- this may be a shared constraint, e.g. from a subtype
1658 -- without a constraint introduced as a generic actual.
1659 -- Examine other discriminants if any.
1662 and then Is_Entity_Name (ItemS)
1666 elsif not Is_OK_Static_Expression (ItemS)
1667 or else not Is_OK_Static_Expression (ItemT)
1671 elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
1672 if Do_Access then -- needs run-time check.
1675 Apply_Compile_Time_Constraint_Error
1676 (N, "incorrect value for discriminant&??",
1677 CE_Discriminant_Check_Failed, Ent => Discr);
1684 Next_Discriminant (Discr);
1693 -- Here we need a discriminant check. First build the expression
1694 -- for the comparisons of the discriminants:
1696 -- (n.disc1 /= typ.disc1) or else
1697 -- (n.disc2 /= typ.disc2) or else
1699 -- (n.discn /= typ.discn)
1701 Cond := Build_Discriminant_Checks (N, T_Typ);
1703 -- If Lhs is set and is a parameter, then the condition is guarded by:
1704 -- lhs'constrained and then (condition built above)
1706 if Present (Param_Entity (Lhs)) then
1710 Make_Attribute_Reference (Loc,
1711 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1712 Attribute_Name => Name_Constrained),
1713 Right_Opnd => Cond);
1717 Cond := Guard_Access (Cond, Loc, N);
1721 Make_Raise_Constraint_Error (Loc,
1723 Reason => CE_Discriminant_Check_Failed));
1724 end Apply_Discriminant_Check;
1726 -------------------------
1727 -- Apply_Divide_Checks --
1728 -------------------------
1730 procedure Apply_Divide_Checks (N : Node_Id) is
1731 Loc : constant Source_Ptr := Sloc (N);
1732 Typ : constant Entity_Id := Etype (N);
1733 Left : constant Node_Id := Left_Opnd (N);
1734 Right : constant Node_Id := Right_Opnd (N);
1736 Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
1737 -- Current overflow checking mode
1747 pragma Warnings (Off, Lhi);
1748 -- Don't actually use this value
1751 -- If we are operating in MINIMIZED or ELIMINATED mode, and we are
1752 -- operating on signed integer types, then the only thing this routine
1753 -- does is to call Apply_Arithmetic_Overflow_Minimized_Eliminated. That
1754 -- procedure will (possibly later on during recursive downward calls),
1755 -- ensure that any needed overflow/division checks are properly applied.
1757 if Mode in Minimized_Or_Eliminated
1758 and then Is_Signed_Integer_Type (Typ)
1760 Apply_Arithmetic_Overflow_Minimized_Eliminated (N);
1764 -- Proceed here in SUPPRESSED or CHECKED modes
1767 and then not Backend_Divide_Checks_On_Target
1768 and then Check_Needed (Right, Division_Check)
1770 Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True);
1772 -- Deal with division check
1774 if Do_Division_Check (N)
1775 and then not Division_Checks_Suppressed (Typ)
1777 Apply_Division_Check (N, Rlo, Rhi, ROK);
1780 -- Deal with overflow check
1782 if Do_Overflow_Check (N)
1783 and then not Overflow_Checks_Suppressed (Etype (N))
1785 Set_Do_Overflow_Check (N, False);
1787 -- Test for extremely annoying case of xxx'First divided by -1
1788 -- for division of signed integer types (only overflow case).
1790 if Nkind (N) = N_Op_Divide
1791 and then Is_Signed_Integer_Type (Typ)
1793 Determine_Range (Left, LOK, Llo, Lhi, Assume_Valid => True);
1794 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1796 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1798 ((not LOK) or else (Llo = LLB))
1801 Make_Raise_Constraint_Error (Loc,
1807 Duplicate_Subexpr_Move_Checks (Left),
1808 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1812 Left_Opnd => Duplicate_Subexpr (Right),
1813 Right_Opnd => Make_Integer_Literal (Loc, -1))),
1815 Reason => CE_Overflow_Check_Failed));
1820 end Apply_Divide_Checks;
1822 --------------------------
1823 -- Apply_Division_Check --
1824 --------------------------
1826 procedure Apply_Division_Check
1832 pragma Assert (Do_Division_Check (N));
1834 Loc : constant Source_Ptr := Sloc (N);
1835 Right : constant Node_Id := Right_Opnd (N);
1839 and then not Backend_Divide_Checks_On_Target
1840 and then Check_Needed (Right, Division_Check)
1842 -- See if division by zero possible, and if so generate test. This
1843 -- part of the test is not controlled by the -gnato switch, since
1844 -- it is a Division_Check and not an Overflow_Check.
1846 if Do_Division_Check (N) then
1847 Set_Do_Division_Check (N, False);
1849 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1851 Make_Raise_Constraint_Error (Loc,
1854 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1855 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1856 Reason => CE_Divide_By_Zero));
1860 end Apply_Division_Check;
1862 ----------------------------------
1863 -- Apply_Float_Conversion_Check --
1864 ----------------------------------
1866 -- Let F and I be the source and target types of the conversion. The RM
1867 -- specifies that a floating-point value X is rounded to the nearest
1868 -- integer, with halfway cases being rounded away from zero. The rounded
1869 -- value of X is checked against I'Range.
1871 -- The catch in the above paragraph is that there is no good way to know
1872 -- whether the round-to-integer operation resulted in overflow. A remedy is
1873 -- to perform a range check in the floating-point domain instead, however:
1875 -- (1) The bounds may not be known at compile time
1876 -- (2) The check must take into account rounding or truncation.
1877 -- (3) The range of type I may not be exactly representable in F.
1878 -- (4) For the rounding case, The end-points I'First - 0.5 and
1879 -- I'Last + 0.5 may or may not be in range, depending on the
1880 -- sign of I'First and I'Last.
1881 -- (5) X may be a NaN, which will fail any comparison
1883 -- The following steps correctly convert X with rounding:
1885 -- (1) If either I'First or I'Last is not known at compile time, use
1886 -- I'Base instead of I in the next three steps and perform a
1887 -- regular range check against I'Range after conversion.
1888 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1889 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1890 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1891 -- In other words, take one of the closest floating-point numbers
1892 -- (which is an integer value) to I'First, and see if it is in
1894 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1895 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1896 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1897 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1898 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1900 -- For the truncating case, replace steps (2) and (3) as follows:
1901 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1902 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1904 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1905 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1908 procedure Apply_Float_Conversion_Check
1910 Target_Typ : Entity_Id)
1912 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1913 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1914 Loc : constant Source_Ptr := Sloc (Ck_Node);
1915 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1916 Target_Base : constant Entity_Id :=
1917 Implementation_Base_Type (Target_Typ);
1919 Par : constant Node_Id := Parent (Ck_Node);
1920 pragma Assert (Nkind (Par) = N_Type_Conversion);
1921 -- Parent of check node, must be a type conversion
1923 Truncate : constant Boolean := Float_Truncate (Par);
1924 Max_Bound : constant Uint :=
1926 (Machine_Radix_Value (Expr_Type),
1927 Machine_Mantissa_Value (Expr_Type) - 1) - 1;
1929 -- Largest bound, so bound plus or minus half is a machine number of F
1931 Ifirst, Ilast : Uint;
1932 -- Bounds of integer type
1935 -- Bounds to check in floating-point domain
1937 Lo_OK, Hi_OK : Boolean;
1938 -- True iff Lo resp. Hi belongs to I'Range
1940 Lo_Chk, Hi_Chk : Node_Id;
1941 -- Expressions that are False iff check fails
1943 Reason : RT_Exception_Code;
1946 -- We do not need checks if we are not generating code (i.e. the full
1947 -- expander is not active). In SPARK mode, we specifically don't want
1948 -- the frontend to expand these checks, which are dealt with directly
1949 -- in the formal verification backend.
1951 if not Expander_Active then
1955 if not Compile_Time_Known_Value (LB)
1956 or not Compile_Time_Known_Value (HB)
1959 -- First check that the value falls in the range of the base type,
1960 -- to prevent overflow during conversion and then perform a
1961 -- regular range check against the (dynamic) bounds.
1963 pragma Assert (Target_Base /= Target_Typ);
1965 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Par);
1968 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1969 Set_Etype (Temp, Target_Base);
1971 Insert_Action (Parent (Par),
1972 Make_Object_Declaration (Loc,
1973 Defining_Identifier => Temp,
1974 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1975 Expression => New_Copy_Tree (Par)),
1976 Suppress => All_Checks);
1979 Make_Raise_Constraint_Error (Loc,
1982 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1983 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1984 Reason => CE_Range_Check_Failed));
1985 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
1991 -- Get the (static) bounds of the target type
1993 Ifirst := Expr_Value (LB);
1994 Ilast := Expr_Value (HB);
1996 -- A simple optimization: if the expression is a universal literal,
1997 -- we can do the comparison with the bounds and the conversion to
1998 -- an integer type statically. The range checks are unchanged.
2000 if Nkind (Ck_Node) = N_Real_Literal
2001 and then Etype (Ck_Node) = Universal_Real
2002 and then Is_Integer_Type (Target_Typ)
2003 and then Nkind (Parent (Ck_Node)) = N_Type_Conversion
2006 Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node));
2009 if Int_Val <= Ilast and then Int_Val >= Ifirst then
2011 -- Conversion is safe
2013 Rewrite (Parent (Ck_Node),
2014 Make_Integer_Literal (Loc, UI_To_Int (Int_Val)));
2015 Analyze_And_Resolve (Parent (Ck_Node), Target_Typ);
2021 -- Check against lower bound
2023 if Truncate and then Ifirst > 0 then
2024 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
2028 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
2031 elsif abs (Ifirst) < Max_Bound then
2032 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
2033 Lo_OK := (Ifirst > 0);
2036 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
2037 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
2042 -- Lo_Chk := (X >= Lo)
2044 Lo_Chk := Make_Op_Ge (Loc,
2045 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2046 Right_Opnd => Make_Real_Literal (Loc, Lo));
2049 -- Lo_Chk := (X > Lo)
2051 Lo_Chk := Make_Op_Gt (Loc,
2052 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2053 Right_Opnd => Make_Real_Literal (Loc, Lo));
2056 -- Check against higher bound
2058 if Truncate and then Ilast < 0 then
2059 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
2063 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
2066 elsif abs (Ilast) < Max_Bound then
2067 Hi := UR_From_Uint (Ilast) + Ureal_Half;
2068 Hi_OK := (Ilast < 0);
2070 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
2071 Hi_OK := (Hi <= UR_From_Uint (Ilast));
2076 -- Hi_Chk := (X <= Hi)
2078 Hi_Chk := Make_Op_Le (Loc,
2079 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2080 Right_Opnd => Make_Real_Literal (Loc, Hi));
2083 -- Hi_Chk := (X < Hi)
2085 Hi_Chk := Make_Op_Lt (Loc,
2086 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2087 Right_Opnd => Make_Real_Literal (Loc, Hi));
2090 -- If the bounds of the target type are the same as those of the base
2091 -- type, the check is an overflow check as a range check is not
2092 -- performed in these cases.
2094 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
2095 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
2097 Reason := CE_Overflow_Check_Failed;
2099 Reason := CE_Range_Check_Failed;
2102 -- Raise CE if either conditions does not hold
2104 Insert_Action (Ck_Node,
2105 Make_Raise_Constraint_Error (Loc,
2106 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
2108 end Apply_Float_Conversion_Check;
2110 ------------------------
2111 -- Apply_Length_Check --
2112 ------------------------
2114 procedure Apply_Length_Check
2116 Target_Typ : Entity_Id;
2117 Source_Typ : Entity_Id := Empty)
2120 Apply_Selected_Length_Checks
2121 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
2122 end Apply_Length_Check;
2124 -------------------------------------
2125 -- Apply_Parameter_Aliasing_Checks --
2126 -------------------------------------
2128 procedure Apply_Parameter_Aliasing_Checks
2132 Loc : constant Source_Ptr := Sloc (Call);
2134 function May_Cause_Aliasing
2135 (Formal_1 : Entity_Id;
2136 Formal_2 : Entity_Id) return Boolean;
2137 -- Determine whether two formal parameters can alias each other
2138 -- depending on their modes.
2140 function Original_Actual (N : Node_Id) return Node_Id;
2141 -- The expander may replace an actual with a temporary for the sake of
2142 -- side effect removal. The temporary may hide a potential aliasing as
2143 -- it does not share the address of the actual. This routine attempts
2144 -- to retrieve the original actual.
2146 procedure Overlap_Check
2147 (Actual_1 : Node_Id;
2149 Formal_1 : Entity_Id;
2150 Formal_2 : Entity_Id;
2151 Check : in out Node_Id);
2152 -- Create a check to determine whether Actual_1 overlaps with Actual_2.
2153 -- If detailed exception messages are enabled, the check is augmented to
2154 -- provide information about the names of the corresponding formals. See
2155 -- the body for details. Actual_1 and Actual_2 denote the two actuals to
2156 -- be tested. Formal_1 and Formal_2 denote the corresponding formals.
2157 -- Check contains all and-ed simple tests generated so far or remains
2158 -- unchanged in the case of detailed exception messaged.
2160 ------------------------
2161 -- May_Cause_Aliasing --
2162 ------------------------
2164 function May_Cause_Aliasing
2165 (Formal_1 : Entity_Id;
2166 Formal_2 : Entity_Id) return Boolean
2169 -- The following combination cannot lead to aliasing
2171 -- Formal 1 Formal 2
2174 if Ekind (Formal_1) = E_In_Parameter
2176 Ekind (Formal_2) = E_In_Parameter
2180 -- The following combinations may lead to aliasing
2182 -- Formal 1 Formal 2
2192 end May_Cause_Aliasing;
2194 ---------------------
2195 -- Original_Actual --
2196 ---------------------
2198 function Original_Actual (N : Node_Id) return Node_Id is
2200 if Nkind (N) = N_Type_Conversion then
2201 return Expression (N);
2203 -- The expander created a temporary to capture the result of a type
2204 -- conversion where the expression is the real actual.
2206 elsif Nkind (N) = N_Identifier
2207 and then Present (Original_Node (N))
2208 and then Nkind (Original_Node (N)) = N_Type_Conversion
2210 return Expression (Original_Node (N));
2214 end Original_Actual;
2220 procedure Overlap_Check
2221 (Actual_1 : Node_Id;
2223 Formal_1 : Entity_Id;
2224 Formal_2 : Entity_Id;
2225 Check : in out Node_Id)
2228 ID_Casing : constant Casing_Type :=
2229 Identifier_Casing (Source_Index (Current_Sem_Unit));
2233 -- Actual_1'Overlaps_Storage (Actual_2)
2236 Make_Attribute_Reference (Loc,
2237 Prefix => New_Copy_Tree (Original_Actual (Actual_1)),
2238 Attribute_Name => Name_Overlaps_Storage,
2240 New_List (New_Copy_Tree (Original_Actual (Actual_2))));
2242 -- Generate the following check when detailed exception messages are
2245 -- if Actual_1'Overlaps_Storage (Actual_2) then
2246 -- raise Program_Error with <detailed message>;
2249 if Exception_Extra_Info then
2252 -- Do not generate location information for internal calls
2254 if Comes_From_Source (Call) then
2255 Store_String_Chars (Build_Location_String (Loc));
2256 Store_String_Char (' ');
2259 Store_String_Chars ("aliased parameters, actuals for """);
2261 Get_Name_String (Chars (Formal_1));
2262 Set_Casing (ID_Casing);
2263 Store_String_Chars (Name_Buffer (1 .. Name_Len));
2265 Store_String_Chars (""" and """);
2267 Get_Name_String (Chars (Formal_2));
2268 Set_Casing (ID_Casing);
2269 Store_String_Chars (Name_Buffer (1 .. Name_Len));
2271 Store_String_Chars (""" overlap");
2273 Insert_Action (Call,
2274 Make_If_Statement (Loc,
2276 Then_Statements => New_List (
2277 Make_Raise_Statement (Loc,
2279 New_Occurrence_Of (Standard_Program_Error, Loc),
2280 Expression => Make_String_Literal (Loc, End_String)))));
2282 -- Create a sequence of overlapping checks by and-ing them all
2292 Right_Opnd => Cond);
2302 Formal_1 : Entity_Id;
2303 Formal_2 : Entity_Id;
2304 Orig_Act_1 : Node_Id;
2305 Orig_Act_2 : Node_Id;
2307 -- Start of processing for Apply_Parameter_Aliasing_Checks
2312 Actual_1 := First_Actual (Call);
2313 Formal_1 := First_Formal (Subp);
2314 while Present (Actual_1) and then Present (Formal_1) loop
2315 Orig_Act_1 := Original_Actual (Actual_1);
2317 -- Ensure that the actual is an object that is not passed by value.
2318 -- Elementary types are always passed by value, therefore actuals of
2319 -- such types cannot lead to aliasing. An aggregate is an object in
2320 -- Ada 2012, but an actual that is an aggregate cannot overlap with
2321 -- another actual. A type that is By_Reference (such as an array of
2322 -- controlled types) is not subject to the check because any update
2323 -- will be done in place and a subsequent read will always see the
2324 -- correct value, see RM 6.2 (12/3).
2326 if Nkind (Orig_Act_1) = N_Aggregate
2327 or else (Nkind (Orig_Act_1) = N_Qualified_Expression
2328 and then Nkind (Expression (Orig_Act_1)) = N_Aggregate)
2332 elsif Is_Object_Reference (Orig_Act_1)
2333 and then not Is_Elementary_Type (Etype (Orig_Act_1))
2334 and then not Is_By_Reference_Type (Etype (Orig_Act_1))
2336 Actual_2 := Next_Actual (Actual_1);
2337 Formal_2 := Next_Formal (Formal_1);
2338 while Present (Actual_2) and then Present (Formal_2) loop
2339 Orig_Act_2 := Original_Actual (Actual_2);
2341 -- The other actual we are testing against must also denote
2342 -- a non pass-by-value object. Generate the check only when
2343 -- the mode of the two formals may lead to aliasing.
2345 if Is_Object_Reference (Orig_Act_2)
2346 and then not Is_Elementary_Type (Etype (Orig_Act_2))
2347 and then May_Cause_Aliasing (Formal_1, Formal_2)
2350 (Actual_1 => Actual_1,
2351 Actual_2 => Actual_2,
2352 Formal_1 => Formal_1,
2353 Formal_2 => Formal_2,
2357 Next_Actual (Actual_2);
2358 Next_Formal (Formal_2);
2362 Next_Actual (Actual_1);
2363 Next_Formal (Formal_1);
2366 -- Place a simple check right before the call
2368 if Present (Check) and then not Exception_Extra_Info then
2369 Insert_Action (Call,
2370 Make_Raise_Program_Error (Loc,
2372 Reason => PE_Aliased_Parameters));
2374 end Apply_Parameter_Aliasing_Checks;
2376 -------------------------------------
2377 -- Apply_Parameter_Validity_Checks --
2378 -------------------------------------
2380 procedure Apply_Parameter_Validity_Checks (Subp : Entity_Id) is
2381 Subp_Decl : Node_Id;
2383 procedure Add_Validity_Check
2384 (Formal : Entity_Id;
2386 For_Result : Boolean := False);
2387 -- Add a single 'Valid[_Scalar] check which verifies the initialization
2388 -- of Formal. Prag_Nam denotes the pre or post condition pragma name.
2389 -- Set flag For_Result when to verify the result of a function.
2391 ------------------------
2392 -- Add_Validity_Check --
2393 ------------------------
2395 procedure Add_Validity_Check
2396 (Formal : Entity_Id;
2398 For_Result : Boolean := False)
2400 procedure Build_Pre_Post_Condition (Expr : Node_Id);
2401 -- Create a pre/postcondition pragma that tests expression Expr
2403 ------------------------------
2404 -- Build_Pre_Post_Condition --
2405 ------------------------------
2407 procedure Build_Pre_Post_Condition (Expr : Node_Id) is
2408 Loc : constant Source_Ptr := Sloc (Subp);
2415 Pragma_Identifier =>
2416 Make_Identifier (Loc, Prag_Nam),
2417 Pragma_Argument_Associations => New_List (
2418 Make_Pragma_Argument_Association (Loc,
2419 Chars => Name_Check,
2420 Expression => Expr)));
2422 -- Add a message unless exception messages are suppressed
2424 if not Exception_Locations_Suppressed then
2425 Append_To (Pragma_Argument_Associations (Prag),
2426 Make_Pragma_Argument_Association (Loc,
2427 Chars => Name_Message,
2429 Make_String_Literal (Loc,
2431 & Get_Name_String (Prag_Nam)
2433 & Build_Location_String (Loc))));
2436 -- Insert the pragma in the tree
2438 if Nkind (Parent (Subp_Decl)) = N_Compilation_Unit then
2439 Add_Global_Declaration (Prag);
2442 -- PPC pragmas associated with subprogram bodies must be inserted
2443 -- in the declarative part of the body.
2445 elsif Nkind (Subp_Decl) = N_Subprogram_Body then
2446 Decls := Declarations (Subp_Decl);
2450 Set_Declarations (Subp_Decl, Decls);
2453 Prepend_To (Decls, Prag);
2456 -- For subprogram declarations insert the PPC pragma right after
2457 -- the declarative node.
2460 Insert_After_And_Analyze (Subp_Decl, Prag);
2462 end Build_Pre_Post_Condition;
2466 Loc : constant Source_Ptr := Sloc (Subp);
2467 Typ : constant Entity_Id := Etype (Formal);
2471 -- Start of processing for Add_Validity_Check
2474 -- For scalars, generate 'Valid test
2476 if Is_Scalar_Type (Typ) then
2479 -- For any non-scalar with scalar parts, generate 'Valid_Scalars test
2481 elsif Scalar_Part_Present (Typ) then
2482 Nam := Name_Valid_Scalars;
2484 -- No test needed for other cases (no scalars to test)
2490 -- Step 1: Create the expression to verify the validity of the
2493 Check := New_Occurrence_Of (Formal, Loc);
2495 -- When processing a function result, use 'Result. Generate
2500 Make_Attribute_Reference (Loc,
2502 Attribute_Name => Name_Result);
2506 -- Context['Result]'Valid[_Scalars]
2509 Make_Attribute_Reference (Loc,
2511 Attribute_Name => Nam);
2513 -- Step 2: Create a pre or post condition pragma
2515 Build_Pre_Post_Condition (Check);
2516 end Add_Validity_Check;
2521 Subp_Spec : Node_Id;
2523 -- Start of processing for Apply_Parameter_Validity_Checks
2526 -- Extract the subprogram specification and declaration nodes
2528 Subp_Spec := Parent (Subp);
2530 if Nkind (Subp_Spec) = N_Defining_Program_Unit_Name then
2531 Subp_Spec := Parent (Subp_Spec);
2534 Subp_Decl := Parent (Subp_Spec);
2536 if not Comes_From_Source (Subp)
2538 -- Do not process formal subprograms because the corresponding actual
2539 -- will receive the proper checks when the instance is analyzed.
2541 or else Is_Formal_Subprogram (Subp)
2543 -- Do not process imported subprograms since pre and postconditions
2544 -- are never verified on routines coming from a different language.
2546 or else Is_Imported (Subp)
2547 or else Is_Intrinsic_Subprogram (Subp)
2549 -- The PPC pragmas generated by this routine do not correspond to
2550 -- source aspects, therefore they cannot be applied to abstract
2553 or else Nkind (Subp_Decl) = N_Abstract_Subprogram_Declaration
2555 -- Do not consider subprogram renaminds because the renamed entity
2556 -- already has the proper PPC pragmas.
2558 or else Nkind (Subp_Decl) = N_Subprogram_Renaming_Declaration
2560 -- Do not process null procedures because there is no benefit of
2561 -- adding the checks to a no action routine.
2563 or else (Nkind (Subp_Spec) = N_Procedure_Specification
2564 and then Null_Present (Subp_Spec))
2569 -- Inspect all the formals applying aliasing and scalar initialization
2570 -- checks where applicable.
2572 Formal := First_Formal (Subp);
2573 while Present (Formal) loop
2575 -- Generate the following scalar initialization checks for each
2576 -- formal parameter:
2578 -- mode IN - Pre => Formal'Valid[_Scalars]
2579 -- mode IN OUT - Pre, Post => Formal'Valid[_Scalars]
2580 -- mode OUT - Post => Formal'Valid[_Scalars]
2582 if Check_Validity_Of_Parameters then
2583 if Ekind_In (Formal, E_In_Parameter, E_In_Out_Parameter) then
2584 Add_Validity_Check (Formal, Name_Precondition, False);
2587 if Ekind_In (Formal, E_In_Out_Parameter, E_Out_Parameter) then
2588 Add_Validity_Check (Formal, Name_Postcondition, False);
2592 Next_Formal (Formal);
2595 -- Generate following scalar initialization check for function result:
2597 -- Post => Subp'Result'Valid[_Scalars]
2599 if Check_Validity_Of_Parameters and then Ekind (Subp) = E_Function then
2600 Add_Validity_Check (Subp, Name_Postcondition, True);
2602 end Apply_Parameter_Validity_Checks;
2604 ---------------------------
2605 -- Apply_Predicate_Check --
2606 ---------------------------
2608 procedure Apply_Predicate_Check
2611 Fun : Entity_Id := Empty)
2616 if Predicate_Checks_Suppressed (Empty) then
2619 elsif Predicates_Ignored (Typ) then
2622 elsif Present (Predicate_Function (Typ)) then
2624 while Present (S) and then not Is_Subprogram (S) loop
2628 -- A predicate check does not apply within internally generated
2629 -- subprograms, such as TSS functions.
2631 if Within_Internal_Subprogram then
2634 -- If the check appears within the predicate function itself, it
2635 -- means that the user specified a check whose formal is the
2636 -- predicated subtype itself, rather than some covering type. This
2637 -- is likely to be a common error, and thus deserves a warning.
2639 elsif Present (S) and then S = Predicate_Function (Typ) then
2641 ("predicate check includes a call to& that requires a "
2642 & "predicate check??", Parent (N), Fun);
2644 ("\this will result in infinite recursion??", Parent (N));
2646 if Is_First_Subtype (Typ) then
2648 ("\use an explicit subtype of& to carry the predicate",
2653 Make_Raise_Storage_Error (Sloc (N),
2654 Reason => SE_Infinite_Recursion));
2656 -- Here for normal case of predicate active
2659 -- If the type has a static predicate and the expression is known
2660 -- at compile time, see if the expression satisfies the predicate.
2662 Check_Expression_Against_Static_Predicate (N, Typ);
2664 if not Expander_Active then
2668 -- For an entity of the type, generate a call to the predicate
2669 -- function, unless its type is an actual subtype, which is not
2670 -- visible outside of the enclosing subprogram.
2672 if Is_Entity_Name (N)
2673 and then not Is_Actual_Subtype (Typ)
2676 Make_Predicate_Check
2677 (Typ, New_Occurrence_Of (Entity (N), Sloc (N))));
2679 -- If the expression is not an entity it may have side effects,
2680 -- and the following call will create an object declaration for
2681 -- it. We disable checks during its analysis, to prevent an
2682 -- infinite recursion.
2686 Make_Predicate_Check
2687 (Typ, Duplicate_Subexpr (N)), Suppress => All_Checks);
2691 end Apply_Predicate_Check;
2693 -----------------------
2694 -- Apply_Range_Check --
2695 -----------------------
2697 procedure Apply_Range_Check
2699 Target_Typ : Entity_Id;
2700 Source_Typ : Entity_Id := Empty)
2703 Apply_Selected_Range_Checks
2704 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
2705 end Apply_Range_Check;
2707 ------------------------------
2708 -- Apply_Scalar_Range_Check --
2709 ------------------------------
2711 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
2712 -- off if it is already set on.
2714 procedure Apply_Scalar_Range_Check
2716 Target_Typ : Entity_Id;
2717 Source_Typ : Entity_Id := Empty;
2718 Fixed_Int : Boolean := False)
2720 Parnt : constant Node_Id := Parent (Expr);
2722 Arr : Node_Id := Empty; -- initialize to prevent warning
2723 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
2726 Is_Subscr_Ref : Boolean;
2727 -- Set true if Expr is a subscript
2729 Is_Unconstrained_Subscr_Ref : Boolean;
2730 -- Set true if Expr is a subscript of an unconstrained array. In this
2731 -- case we do not attempt to do an analysis of the value against the
2732 -- range of the subscript, since we don't know the actual subtype.
2735 -- Set to True if Expr should be regarded as a real value even though
2736 -- the type of Expr might be discrete.
2738 procedure Bad_Value (Warn : Boolean := False);
2739 -- Procedure called if value is determined to be out of range. Warn is
2740 -- True to force a warning instead of an error, even when SPARK_Mode is
2747 procedure Bad_Value (Warn : Boolean := False) is
2749 Apply_Compile_Time_Constraint_Error
2750 (Expr, "value not in range of}??", CE_Range_Check_Failed,
2756 -- Start of processing for Apply_Scalar_Range_Check
2759 -- Return if check obviously not needed
2762 -- Not needed inside generic
2766 -- Not needed if previous error
2768 or else Target_Typ = Any_Type
2769 or else Nkind (Expr) = N_Error
2771 -- Not needed for non-scalar type
2773 or else not Is_Scalar_Type (Target_Typ)
2775 -- Not needed if we know node raises CE already
2777 or else Raises_Constraint_Error (Expr)
2782 -- Now, see if checks are suppressed
2785 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
2787 if Is_Subscr_Ref then
2788 Arr := Prefix (Parnt);
2789 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
2791 if Is_Access_Type (Arr_Typ) then
2792 Arr_Typ := Designated_Type (Arr_Typ);
2796 if not Do_Range_Check (Expr) then
2798 -- Subscript reference. Check for Index_Checks suppressed
2800 if Is_Subscr_Ref then
2802 -- Check array type and its base type
2804 if Index_Checks_Suppressed (Arr_Typ)
2805 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
2809 -- Check array itself if it is an entity name
2811 elsif Is_Entity_Name (Arr)
2812 and then Index_Checks_Suppressed (Entity (Arr))
2816 -- Check expression itself if it is an entity name
2818 elsif Is_Entity_Name (Expr)
2819 and then Index_Checks_Suppressed (Entity (Expr))
2824 -- All other cases, check for Range_Checks suppressed
2827 -- Check target type and its base type
2829 if Range_Checks_Suppressed (Target_Typ)
2830 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
2834 -- Check expression itself if it is an entity name
2836 elsif Is_Entity_Name (Expr)
2837 and then Range_Checks_Suppressed (Entity (Expr))
2841 -- If Expr is part of an assignment statement, then check left
2842 -- side of assignment if it is an entity name.
2844 elsif Nkind (Parnt) = N_Assignment_Statement
2845 and then Is_Entity_Name (Name (Parnt))
2846 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
2853 -- Do not set range checks if they are killed
2855 if Nkind (Expr) = N_Unchecked_Type_Conversion
2856 and then Kill_Range_Check (Expr)
2861 -- Do not set range checks for any values from System.Scalar_Values
2862 -- since the whole idea of such values is to avoid checking them.
2864 if Is_Entity_Name (Expr)
2865 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
2870 -- Now see if we need a check
2872 if No (Source_Typ) then
2873 S_Typ := Etype (Expr);
2875 S_Typ := Source_Typ;
2878 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
2882 Is_Unconstrained_Subscr_Ref :=
2883 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
2885 -- Special checks for floating-point type
2887 if Is_Floating_Point_Type (S_Typ) then
2889 -- Always do a range check if the source type includes infinities and
2890 -- the target type does not include infinities. We do not do this if
2891 -- range checks are killed.
2892 -- If the expression is a literal and the bounds of the type are
2893 -- static constants it may be possible to optimize the check.
2895 if Has_Infinities (S_Typ)
2896 and then not Has_Infinities (Target_Typ)
2898 -- If the expression is a literal and the bounds of the type are
2899 -- static constants it may be possible to optimize the check.
2901 if Nkind (Expr) = N_Real_Literal then
2903 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
2904 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
2907 if Compile_Time_Known_Value (Tlo)
2908 and then Compile_Time_Known_Value (Thi)
2909 and then Expr_Value_R (Expr) >= Expr_Value_R (Tlo)
2910 and then Expr_Value_R (Expr) <= Expr_Value_R (Thi)
2914 Enable_Range_Check (Expr);
2919 Enable_Range_Check (Expr);
2924 -- Return if we know expression is definitely in the range of the target
2925 -- type as determined by Determine_Range. Right now we only do this for
2926 -- discrete types, and not fixed-point or floating-point types.
2928 -- The additional less-precise tests below catch these cases
2930 -- Note: skip this if we are given a source_typ, since the point of
2931 -- supplying a Source_Typ is to stop us looking at the expression.
2932 -- We could sharpen this test to be out parameters only ???
2934 if Is_Discrete_Type (Target_Typ)
2935 and then Is_Discrete_Type (Etype (Expr))
2936 and then not Is_Unconstrained_Subscr_Ref
2937 and then No (Source_Typ)
2940 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
2941 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
2946 if Compile_Time_Known_Value (Tlo)
2947 and then Compile_Time_Known_Value (Thi)
2950 Lov : constant Uint := Expr_Value (Tlo);
2951 Hiv : constant Uint := Expr_Value (Thi);
2954 -- If range is null, we for sure have a constraint error
2955 -- (we don't even need to look at the value involved,
2956 -- since all possible values will raise CE).
2960 -- When SPARK_Mode is On, force a warning instead of
2961 -- an error in that case, as this likely corresponds
2962 -- to deactivated code.
2964 Bad_Value (Warn => SPARK_Mode = On);
2966 -- In GNATprove mode, we enable the range check so that
2967 -- GNATprove will issue a message if it cannot be proved.
2969 if GNATprove_Mode then
2970 Enable_Range_Check (Expr);
2976 -- Otherwise determine range of value
2978 Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True);
2982 -- If definitely in range, all OK
2984 if Lo >= Lov and then Hi <= Hiv then
2987 -- If definitely not in range, warn
2989 elsif Lov > Hi or else Hiv < Lo then
2993 -- Otherwise we don't know
3005 Is_Floating_Point_Type (S_Typ)
3006 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
3008 -- Check if we can determine at compile time whether Expr is in the
3009 -- range of the target type. Note that if S_Typ is within the bounds
3010 -- of Target_Typ then this must be the case. This check is meaningful
3011 -- only if this is not a conversion between integer and real types.
3013 if not Is_Unconstrained_Subscr_Ref
3014 and then Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
3016 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
3018 -- Also check if the expression itself is in the range of the
3019 -- target type if it is a known at compile time value. We skip
3020 -- this test if S_Typ is set since for OUT and IN OUT parameters
3021 -- the Expr itself is not relevant to the checking.
3025 and then Is_In_Range (Expr, Target_Typ,
3026 Assume_Valid => True,
3027 Fixed_Int => Fixed_Int,
3028 Int_Real => Int_Real)))
3032 elsif Is_Out_Of_Range (Expr, Target_Typ,
3033 Assume_Valid => True,
3034 Fixed_Int => Fixed_Int,
3035 Int_Real => Int_Real)
3040 -- Floating-point case
3041 -- In the floating-point case, we only do range checks if the type is
3042 -- constrained. We definitely do NOT want range checks for unconstrained
3043 -- types, since we want to have infinities, except when
3044 -- Check_Float_Overflow is set.
3046 elsif Is_Floating_Point_Type (S_Typ) then
3047 if Is_Constrained (S_Typ) or else Check_Float_Overflow then
3048 Enable_Range_Check (Expr);
3051 -- For all other cases we enable a range check unconditionally
3054 Enable_Range_Check (Expr);
3057 end Apply_Scalar_Range_Check;
3059 ----------------------------------
3060 -- Apply_Selected_Length_Checks --
3061 ----------------------------------
3063 procedure Apply_Selected_Length_Checks
3065 Target_Typ : Entity_Id;
3066 Source_Typ : Entity_Id;
3067 Do_Static : Boolean)
3070 R_Result : Check_Result;
3073 Loc : constant Source_Ptr := Sloc (Ck_Node);
3074 Checks_On : constant Boolean :=
3075 (not Index_Checks_Suppressed (Target_Typ))
3076 or else (not Length_Checks_Suppressed (Target_Typ));
3079 -- Note: this means that we lose some useful warnings if the expander
3080 -- is not active, and we also lose these warnings in SPARK mode ???
3082 if not Expander_Active then
3087 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
3089 for J in 1 .. 2 loop
3090 R_Cno := R_Result (J);
3091 exit when No (R_Cno);
3093 -- A length check may mention an Itype which is attached to a
3094 -- subsequent node. At the top level in a package this can cause
3095 -- an order-of-elaboration problem, so we make sure that the itype
3096 -- is referenced now.
3098 if Ekind (Current_Scope) = E_Package
3099 and then Is_Compilation_Unit (Current_Scope)
3101 Ensure_Defined (Target_Typ, Ck_Node);
3103 if Present (Source_Typ) then
3104 Ensure_Defined (Source_Typ, Ck_Node);
3106 elsif Is_Itype (Etype (Ck_Node)) then
3107 Ensure_Defined (Etype (Ck_Node), Ck_Node);
3111 -- If the item is a conditional raise of constraint error, then have
3112 -- a look at what check is being performed and ???
3114 if Nkind (R_Cno) = N_Raise_Constraint_Error
3115 and then Present (Condition (R_Cno))
3117 Cond := Condition (R_Cno);
3119 -- Case where node does not now have a dynamic check
3121 if not Has_Dynamic_Length_Check (Ck_Node) then
3123 -- If checks are on, just insert the check
3126 Insert_Action (Ck_Node, R_Cno);
3128 if not Do_Static then
3129 Set_Has_Dynamic_Length_Check (Ck_Node);
3132 -- If checks are off, then analyze the length check after
3133 -- temporarily attaching it to the tree in case the relevant
3134 -- condition can be evaluated at compile time. We still want a
3135 -- compile time warning in this case.
3138 Set_Parent (R_Cno, Ck_Node);
3143 -- Output a warning if the condition is known to be True
3145 if Is_Entity_Name (Cond)
3146 and then Entity (Cond) = Standard_True
3148 Apply_Compile_Time_Constraint_Error
3149 (Ck_Node, "wrong length for array of}??",
3150 CE_Length_Check_Failed,
3154 -- If we were only doing a static check, or if checks are not
3155 -- on, then we want to delete the check, since it is not needed.
3156 -- We do this by replacing the if statement by a null statement
3158 elsif Do_Static or else not Checks_On then
3159 Remove_Warning_Messages (R_Cno);
3160 Rewrite (R_Cno, Make_Null_Statement (Loc));
3164 Install_Static_Check (R_Cno, Loc);
3167 end Apply_Selected_Length_Checks;
3169 ---------------------------------
3170 -- Apply_Selected_Range_Checks --
3171 ---------------------------------
3173 procedure Apply_Selected_Range_Checks
3175 Target_Typ : Entity_Id;
3176 Source_Typ : Entity_Id;
3177 Do_Static : Boolean)
3179 Loc : constant Source_Ptr := Sloc (Ck_Node);
3180 Checks_On : constant Boolean :=
3181 not Index_Checks_Suppressed (Target_Typ)
3183 not Range_Checks_Suppressed (Target_Typ);
3187 R_Result : Check_Result;
3190 if not Expander_Active or not Checks_On then
3195 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
3197 for J in 1 .. 2 loop
3198 R_Cno := R_Result (J);
3199 exit when No (R_Cno);
3201 -- The range check requires runtime evaluation. Depending on what its
3202 -- triggering condition is, the check may be converted into a compile
3203 -- time constraint check.
3205 if Nkind (R_Cno) = N_Raise_Constraint_Error
3206 and then Present (Condition (R_Cno))
3208 Cond := Condition (R_Cno);
3210 -- Insert the range check before the related context. Note that
3211 -- this action analyses the triggering condition.
3213 Insert_Action (Ck_Node, R_Cno);
3215 -- This old code doesn't make sense, why is the context flagged as
3216 -- requiring dynamic range checks now in the middle of generating
3219 if not Do_Static then
3220 Set_Has_Dynamic_Range_Check (Ck_Node);
3223 -- The triggering condition evaluates to True, the range check
3224 -- can be converted into a compile time constraint check.
3226 if Is_Entity_Name (Cond)
3227 and then Entity (Cond) = Standard_True
3229 -- Since an N_Range is technically not an expression, we have
3230 -- to set one of the bounds to C_E and then just flag the
3231 -- N_Range. The warning message will point to the lower bound
3232 -- and complain about a range, which seems OK.
3234 if Nkind (Ck_Node) = N_Range then
3235 Apply_Compile_Time_Constraint_Error
3236 (Low_Bound (Ck_Node),
3237 "static range out of bounds of}??",
3238 CE_Range_Check_Failed,
3242 Set_Raises_Constraint_Error (Ck_Node);
3245 Apply_Compile_Time_Constraint_Error
3247 "static value out of range of}??",
3248 CE_Range_Check_Failed,
3253 -- If we were only doing a static check, or if checks are not
3254 -- on, then we want to delete the check, since it is not needed.
3255 -- We do this by replacing the if statement by a null statement
3257 elsif Do_Static then
3258 Remove_Warning_Messages (R_Cno);
3259 Rewrite (R_Cno, Make_Null_Statement (Loc));
3262 -- The range check raises Constraint_Error explicitly
3265 Install_Static_Check (R_Cno, Loc);
3268 end Apply_Selected_Range_Checks;
3270 -------------------------------
3271 -- Apply_Static_Length_Check --
3272 -------------------------------
3274 procedure Apply_Static_Length_Check
3276 Target_Typ : Entity_Id;
3277 Source_Typ : Entity_Id := Empty)
3280 Apply_Selected_Length_Checks
3281 (Expr, Target_Typ, Source_Typ, Do_Static => True);
3282 end Apply_Static_Length_Check;
3284 -------------------------------------
3285 -- Apply_Subscript_Validity_Checks --
3286 -------------------------------------
3288 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
3292 pragma Assert (Nkind (Expr) = N_Indexed_Component);
3294 -- Loop through subscripts
3296 Sub := First (Expressions (Expr));
3297 while Present (Sub) loop
3299 -- Check one subscript. Note that we do not worry about enumeration
3300 -- type with holes, since we will convert the value to a Pos value
3301 -- for the subscript, and that convert will do the necessary validity
3304 Ensure_Valid (Sub, Holes_OK => True);
3306 -- Move to next subscript
3310 end Apply_Subscript_Validity_Checks;
3312 ----------------------------------
3313 -- Apply_Type_Conversion_Checks --
3314 ----------------------------------
3316 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
3317 Target_Type : constant Entity_Id := Etype (N);
3318 Target_Base : constant Entity_Id := Base_Type (Target_Type);
3319 Expr : constant Node_Id := Expression (N);
3321 Expr_Type : constant Entity_Id := Underlying_Type (Etype (Expr));
3322 -- Note: if Etype (Expr) is a private type without discriminants, its
3323 -- full view might have discriminants with defaults, so we need the
3324 -- full view here to retrieve the constraints.
3327 if Inside_A_Generic then
3330 -- Skip these checks if serious errors detected, there are some nasty
3331 -- situations of incomplete trees that blow things up.
3333 elsif Serious_Errors_Detected > 0 then
3336 -- Never generate discriminant checks for Unchecked_Union types
3338 elsif Present (Expr_Type)
3339 and then Is_Unchecked_Union (Expr_Type)
3343 -- Scalar type conversions of the form Target_Type (Expr) require a
3344 -- range check if we cannot be sure that Expr is in the base type of
3345 -- Target_Typ and also that Expr is in the range of Target_Typ. These
3346 -- are not quite the same condition from an implementation point of
3347 -- view, but clearly the second includes the first.
3349 elsif Is_Scalar_Type (Target_Type) then
3351 Conv_OK : constant Boolean := Conversion_OK (N);
3352 -- If the Conversion_OK flag on the type conversion is set and no
3353 -- floating-point type is involved in the type conversion then
3354 -- fixed-point values must be read as integral values.
3356 Float_To_Int : constant Boolean :=
3357 Is_Floating_Point_Type (Expr_Type)
3358 and then Is_Integer_Type (Target_Type);
3361 if not Overflow_Checks_Suppressed (Target_Base)
3362 and then not Overflow_Checks_Suppressed (Target_Type)
3364 In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK)
3365 and then not Float_To_Int
3367 Activate_Overflow_Check (N);
3370 if not Range_Checks_Suppressed (Target_Type)
3371 and then not Range_Checks_Suppressed (Expr_Type)
3373 if Float_To_Int then
3374 Apply_Float_Conversion_Check (Expr, Target_Type);
3376 Apply_Scalar_Range_Check
3377 (Expr, Target_Type, Fixed_Int => Conv_OK);
3379 -- If the target type has predicates, we need to indicate
3380 -- the need for a check, even if Determine_Range finds that
3381 -- the value is within bounds. This may be the case e.g for
3382 -- a division with a constant denominator.
3384 if Has_Predicates (Target_Type) then
3385 Enable_Range_Check (Expr);
3391 elsif Comes_From_Source (N)
3392 and then not Discriminant_Checks_Suppressed (Target_Type)
3393 and then Is_Record_Type (Target_Type)
3394 and then Is_Derived_Type (Target_Type)
3395 and then not Is_Tagged_Type (Target_Type)
3396 and then not Is_Constrained (Target_Type)
3397 and then Present (Stored_Constraint (Target_Type))
3399 -- An unconstrained derived type may have inherited discriminant.
3400 -- Build an actual discriminant constraint list using the stored
3401 -- constraint, to verify that the expression of the parent type
3402 -- satisfies the constraints imposed by the (unconstrained) derived
3403 -- type. This applies to value conversions, not to view conversions
3407 Loc : constant Source_Ptr := Sloc (N);
3409 Constraint : Elmt_Id;
3410 Discr_Value : Node_Id;
3413 New_Constraints : constant Elist_Id := New_Elmt_List;
3414 Old_Constraints : constant Elist_Id :=
3415 Discriminant_Constraint (Expr_Type);
3418 Constraint := First_Elmt (Stored_Constraint (Target_Type));
3419 while Present (Constraint) loop
3420 Discr_Value := Node (Constraint);
3422 if Is_Entity_Name (Discr_Value)
3423 and then Ekind (Entity (Discr_Value)) = E_Discriminant
3425 Discr := Corresponding_Discriminant (Entity (Discr_Value));
3428 and then Scope (Discr) = Base_Type (Expr_Type)
3430 -- Parent is constrained by new discriminant. Obtain
3431 -- Value of original discriminant in expression. If the
3432 -- new discriminant has been used to constrain more than
3433 -- one of the stored discriminants, this will provide the
3434 -- required consistency check.
3437 (Make_Selected_Component (Loc,
3439 Duplicate_Subexpr_No_Checks
3440 (Expr, Name_Req => True),
3442 Make_Identifier (Loc, Chars (Discr))),
3446 -- Discriminant of more remote ancestor ???
3451 -- Derived type definition has an explicit value for this
3452 -- stored discriminant.
3456 (Duplicate_Subexpr_No_Checks (Discr_Value),
3460 Next_Elmt (Constraint);
3463 -- Use the unconstrained expression type to retrieve the
3464 -- discriminants of the parent, and apply momentarily the
3465 -- discriminant constraint synthesized above.
3467 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
3468 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
3469 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
3472 Make_Raise_Constraint_Error (Loc,
3474 Reason => CE_Discriminant_Check_Failed));
3477 -- For arrays, checks are set now, but conversions are applied during
3478 -- expansion, to take into accounts changes of representation. The
3479 -- checks become range checks on the base type or length checks on the
3480 -- subtype, depending on whether the target type is unconstrained or
3481 -- constrained. Note that the range check is put on the expression of a
3482 -- type conversion, while the length check is put on the type conversion
3485 elsif Is_Array_Type (Target_Type) then
3486 if Is_Constrained (Target_Type) then
3487 Set_Do_Length_Check (N);
3489 Set_Do_Range_Check (Expr);
3492 end Apply_Type_Conversion_Checks;
3494 ----------------------------------------------
3495 -- Apply_Universal_Integer_Attribute_Checks --
3496 ----------------------------------------------
3498 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
3499 Loc : constant Source_Ptr := Sloc (N);
3500 Typ : constant Entity_Id := Etype (N);
3503 if Inside_A_Generic then
3506 -- Nothing to do if checks are suppressed
3508 elsif Range_Checks_Suppressed (Typ)
3509 and then Overflow_Checks_Suppressed (Typ)
3513 -- Nothing to do if the attribute does not come from source. The
3514 -- internal attributes we generate of this type do not need checks,
3515 -- and furthermore the attempt to check them causes some circular
3516 -- elaboration orders when dealing with packed types.
3518 elsif not Comes_From_Source (N) then
3521 -- If the prefix is a selected component that depends on a discriminant
3522 -- the check may improperly expose a discriminant instead of using
3523 -- the bounds of the object itself. Set the type of the attribute to
3524 -- the base type of the context, so that a check will be imposed when
3525 -- needed (e.g. if the node appears as an index).
3527 elsif Nkind (Prefix (N)) = N_Selected_Component
3528 and then Ekind (Typ) = E_Signed_Integer_Subtype
3529 and then Depends_On_Discriminant (Scalar_Range (Typ))
3531 Set_Etype (N, Base_Type (Typ));
3533 -- Otherwise, replace the attribute node with a type conversion node
3534 -- whose expression is the attribute, retyped to universal integer, and
3535 -- whose subtype mark is the target type. The call to analyze this
3536 -- conversion will set range and overflow checks as required for proper
3537 -- detection of an out of range value.
3540 Set_Etype (N, Universal_Integer);
3541 Set_Analyzed (N, True);
3544 Make_Type_Conversion (Loc,
3545 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
3546 Expression => Relocate_Node (N)));
3548 Analyze_And_Resolve (N, Typ);
3551 end Apply_Universal_Integer_Attribute_Checks;
3553 -------------------------------------
3554 -- Atomic_Synchronization_Disabled --
3555 -------------------------------------
3557 -- Note: internally Disable/Enable_Atomic_Synchronization is implemented
3558 -- using a bogus check called Atomic_Synchronization. This is to make it
3559 -- more convenient to get exactly the same semantics as [Un]Suppress.
3561 function Atomic_Synchronization_Disabled (E : Entity_Id) return Boolean is
3563 -- If debug flag d.e is set, always return False, i.e. all atomic sync
3564 -- looks enabled, since it is never disabled.
3566 if Debug_Flag_Dot_E then
3569 -- If debug flag d.d is set then always return True, i.e. all atomic
3570 -- sync looks disabled, since it always tests True.
3572 elsif Debug_Flag_Dot_D then
3575 -- If entity present, then check result for that entity
3577 elsif Present (E) and then Checks_May_Be_Suppressed (E) then
3578 return Is_Check_Suppressed (E, Atomic_Synchronization);
3580 -- Otherwise result depends on current scope setting
3583 return Scope_Suppress.Suppress (Atomic_Synchronization);
3585 end Atomic_Synchronization_Disabled;
3587 -------------------------------
3588 -- Build_Discriminant_Checks --
3589 -------------------------------
3591 function Build_Discriminant_Checks
3593 T_Typ : Entity_Id) return Node_Id
3595 Loc : constant Source_Ptr := Sloc (N);
3598 Disc_Ent : Entity_Id;
3602 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
3604 ----------------------------------
3605 -- Aggregate_Discriminant_Value --
3606 ----------------------------------
3608 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
3612 -- The aggregate has been normalized with named associations. We use
3613 -- the Chars field to locate the discriminant to take into account
3614 -- discriminants in derived types, which carry the same name as those
3617 Assoc := First (Component_Associations (N));
3618 while Present (Assoc) loop
3619 if Chars (First (Choices (Assoc))) = Chars (Disc) then
3620 return Expression (Assoc);
3626 -- Discriminant must have been found in the loop above
3628 raise Program_Error;
3629 end Aggregate_Discriminant_Val;
3631 -- Start of processing for Build_Discriminant_Checks
3634 -- Loop through discriminants evolving the condition
3637 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
3639 -- For a fully private type, use the discriminants of the parent type
3641 if Is_Private_Type (T_Typ)
3642 and then No (Full_View (T_Typ))
3644 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
3646 Disc_Ent := First_Discriminant (T_Typ);
3649 while Present (Disc) loop
3650 Dval := Node (Disc);
3652 if Nkind (Dval) = N_Identifier
3653 and then Ekind (Entity (Dval)) = E_Discriminant
3655 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
3657 Dval := Duplicate_Subexpr_No_Checks (Dval);
3660 -- If we have an Unchecked_Union node, we can infer the discriminants
3663 if Is_Unchecked_Union (Base_Type (T_Typ)) then
3665 Get_Discriminant_Value (
3666 First_Discriminant (T_Typ),
3668 Stored_Constraint (T_Typ)));
3670 elsif Nkind (N) = N_Aggregate then
3672 Duplicate_Subexpr_No_Checks
3673 (Aggregate_Discriminant_Val (Disc_Ent));
3677 Make_Selected_Component (Loc,
3679 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
3680 Selector_Name => Make_Identifier (Loc, Chars (Disc_Ent)));
3682 Set_Is_In_Discriminant_Check (Dref);
3685 Evolve_Or_Else (Cond,
3688 Right_Opnd => Dval));
3691 Next_Discriminant (Disc_Ent);
3695 end Build_Discriminant_Checks;
3701 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
3708 function Left_Expression (Op : Node_Id) return Node_Id;
3709 -- Return the relevant expression from the left operand of the given
3710 -- short circuit form: this is LO itself, except if LO is a qualified
3711 -- expression, a type conversion, or an expression with actions, in
3712 -- which case this is Left_Expression (Expression (LO)).
3714 ---------------------
3715 -- Left_Expression --
3716 ---------------------
3718 function Left_Expression (Op : Node_Id) return Node_Id is
3719 LE : Node_Id := Left_Opnd (Op);
3721 while Nkind_In (LE, N_Qualified_Expression,
3723 N_Expression_With_Actions)
3725 LE := Expression (LE);
3729 end Left_Expression;
3731 -- Start of processing for Check_Needed
3734 -- Always check if not simple entity
3736 if Nkind (Nod) not in N_Has_Entity
3737 or else not Comes_From_Source (Nod)
3742 -- Look up tree for short circuit
3749 -- Done if out of subexpression (note that we allow generated stuff
3750 -- such as itype declarations in this context, to keep the loop going
3751 -- since we may well have generated such stuff in complex situations.
3752 -- Also done if no parent (probably an error condition, but no point
3753 -- in behaving nasty if we find it).
3756 or else (K not in N_Subexpr and then Comes_From_Source (P))
3760 -- Or/Or Else case, where test is part of the right operand, or is
3761 -- part of one of the actions associated with the right operand, and
3762 -- the left operand is an equality test.
3764 elsif K = N_Op_Or then
3765 exit when N = Right_Opnd (P)
3766 and then Nkind (Left_Expression (P)) = N_Op_Eq;
3768 elsif K = N_Or_Else then
3769 exit when (N = Right_Opnd (P)
3772 and then List_Containing (N) = Actions (P)))
3773 and then Nkind (Left_Expression (P)) = N_Op_Eq;
3775 -- Similar test for the And/And then case, where the left operand
3776 -- is an inequality test.
3778 elsif K = N_Op_And then
3779 exit when N = Right_Opnd (P)
3780 and then Nkind (Left_Expression (P)) = N_Op_Ne;
3782 elsif K = N_And_Then then
3783 exit when (N = Right_Opnd (P)
3786 and then List_Containing (N) = Actions (P)))
3787 and then Nkind (Left_Expression (P)) = N_Op_Ne;
3793 -- If we fall through the loop, then we have a conditional with an
3794 -- appropriate test as its left operand, so look further.
3796 L := Left_Expression (P);
3798 -- L is an "=" or "/=" operator: extract its operands
3800 R := Right_Opnd (L);
3803 -- Left operand of test must match original variable
3805 if Nkind (L) not in N_Has_Entity or else Entity (L) /= Entity (Nod) then
3809 -- Right operand of test must be key value (zero or null)
3812 when Access_Check =>
3813 if not Known_Null (R) then
3817 when Division_Check =>
3818 if not Compile_Time_Known_Value (R)
3819 or else Expr_Value (R) /= Uint_0
3825 raise Program_Error;
3828 -- Here we have the optimizable case, warn if not short-circuited
3830 if K = N_Op_And or else K = N_Op_Or then
3831 Error_Msg_Warn := SPARK_Mode /= On;
3834 when Access_Check =>
3835 if GNATprove_Mode then
3837 ("Constraint_Error might have been raised (access check)",
3841 ("Constraint_Error may be raised (access check)??",
3845 when Division_Check =>
3846 if GNATprove_Mode then
3848 ("Constraint_Error might have been raised (zero divide)",
3852 ("Constraint_Error may be raised (zero divide)??",
3857 raise Program_Error;
3860 if K = N_Op_And then
3861 Error_Msg_N -- CODEFIX
3862 ("use `AND THEN` instead of AND??", P);
3864 Error_Msg_N -- CODEFIX
3865 ("use `OR ELSE` instead of OR??", P);
3868 -- If not short-circuited, we need the check
3872 -- If short-circuited, we can omit the check
3879 -----------------------------------
3880 -- Check_Valid_Lvalue_Subscripts --
3881 -----------------------------------
3883 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
3885 -- Skip this if range checks are suppressed
3887 if Range_Checks_Suppressed (Etype (Expr)) then
3890 -- Only do this check for expressions that come from source. We assume
3891 -- that expander generated assignments explicitly include any necessary
3892 -- checks. Note that this is not just an optimization, it avoids
3893 -- infinite recursions.
3895 elsif not Comes_From_Source (Expr) then
3898 -- For a selected component, check the prefix
3900 elsif Nkind (Expr) = N_Selected_Component then
3901 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
3904 -- Case of indexed component
3906 elsif Nkind (Expr) = N_Indexed_Component then
3907 Apply_Subscript_Validity_Checks (Expr);
3909 -- Prefix may itself be or contain an indexed component, and these
3910 -- subscripts need checking as well.
3912 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
3914 end Check_Valid_Lvalue_Subscripts;
3916 ----------------------------------
3917 -- Null_Exclusion_Static_Checks --
3918 ----------------------------------
3920 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
3921 Error_Node : Node_Id;
3923 Has_Null : constant Boolean := Has_Null_Exclusion (N);
3924 K : constant Node_Kind := Nkind (N);
3929 (Nkind_In (K, N_Component_Declaration,
3930 N_Discriminant_Specification,
3931 N_Function_Specification,
3932 N_Object_Declaration,
3933 N_Parameter_Specification));
3935 if K = N_Function_Specification then
3936 Typ := Etype (Defining_Entity (N));
3938 Typ := Etype (Defining_Identifier (N));
3942 when N_Component_Declaration =>
3943 if Present (Access_Definition (Component_Definition (N))) then
3944 Error_Node := Component_Definition (N);
3946 Error_Node := Subtype_Indication (Component_Definition (N));
3949 when N_Discriminant_Specification =>
3950 Error_Node := Discriminant_Type (N);
3952 when N_Function_Specification =>
3953 Error_Node := Result_Definition (N);
3955 when N_Object_Declaration =>
3956 Error_Node := Object_Definition (N);
3958 when N_Parameter_Specification =>
3959 Error_Node := Parameter_Type (N);
3962 raise Program_Error;
3967 -- Enforce legality rule 3.10 (13): A null exclusion can only be
3968 -- applied to an access [sub]type.
3970 if not Is_Access_Type (Typ) then
3972 ("`NOT NULL` allowed only for an access type", Error_Node);
3974 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
3975 -- be applied to a [sub]type that does not exclude null already.
3977 elsif Can_Never_Be_Null (Typ)
3978 and then Comes_From_Source (Typ)
3981 ("`NOT NULL` not allowed (& already excludes null)",
3986 -- Check that null-excluding objects are always initialized, except for
3987 -- deferred constants, for which the expression will appear in the full
3990 if K = N_Object_Declaration
3991 and then No (Expression (N))
3992 and then not Constant_Present (N)
3993 and then not No_Initialization (N)
3995 -- Add an expression that assigns null. This node is needed by
3996 -- Apply_Compile_Time_Constraint_Error, which will replace this with
3997 -- a Constraint_Error node.
3999 Set_Expression (N, Make_Null (Sloc (N)));
4000 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
4002 Apply_Compile_Time_Constraint_Error
4003 (N => Expression (N),
4005 "(Ada 2005) null-excluding objects must be initialized??",
4006 Reason => CE_Null_Not_Allowed);
4009 -- Check that a null-excluding component, formal or object is not being
4010 -- assigned a null value. Otherwise generate a warning message and
4011 -- replace Expression (N) by an N_Constraint_Error node.
4013 if K /= N_Function_Specification then
4014 Expr := Expression (N);
4016 if Present (Expr) and then Known_Null (Expr) then
4018 when N_Component_Declaration |
4019 N_Discriminant_Specification =>
4020 Apply_Compile_Time_Constraint_Error
4022 Msg => "(Ada 2005) null not allowed "
4023 & "in null-excluding components??",
4024 Reason => CE_Null_Not_Allowed);
4026 when N_Object_Declaration =>
4027 Apply_Compile_Time_Constraint_Error
4029 Msg => "(Ada 2005) null not allowed "
4030 & "in null-excluding objects??",
4031 Reason => CE_Null_Not_Allowed);
4033 when N_Parameter_Specification =>
4034 Apply_Compile_Time_Constraint_Error
4036 Msg => "(Ada 2005) null not allowed "
4037 & "in null-excluding formals??",
4038 Reason => CE_Null_Not_Allowed);
4045 end Null_Exclusion_Static_Checks;
4047 ----------------------------------
4048 -- Conditional_Statements_Begin --
4049 ----------------------------------
4051 procedure Conditional_Statements_Begin is
4053 Saved_Checks_TOS := Saved_Checks_TOS + 1;
4055 -- If stack overflows, kill all checks, that way we know to simply reset
4056 -- the number of saved checks to zero on return. This should never occur
4059 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
4062 -- In the normal case, we just make a new stack entry saving the current
4063 -- number of saved checks for a later restore.
4066 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
4068 if Debug_Flag_CC then
4069 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
4073 end Conditional_Statements_Begin;
4075 --------------------------------
4076 -- Conditional_Statements_End --
4077 --------------------------------
4079 procedure Conditional_Statements_End is
4081 pragma Assert (Saved_Checks_TOS > 0);
4083 -- If the saved checks stack overflowed, then we killed all checks, so
4084 -- setting the number of saved checks back to zero is correct. This
4085 -- should never occur in practice.
4087 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
4088 Num_Saved_Checks := 0;
4090 -- In the normal case, restore the number of saved checks from the top
4094 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
4096 if Debug_Flag_CC then
4097 w ("Conditional_Statements_End: Num_Saved_Checks = ",
4102 Saved_Checks_TOS := Saved_Checks_TOS - 1;
4103 end Conditional_Statements_End;
4105 -------------------------
4106 -- Convert_From_Bignum --
4107 -------------------------
4109 function Convert_From_Bignum (N : Node_Id) return Node_Id is
4110 Loc : constant Source_Ptr := Sloc (N);
4113 pragma Assert (Is_RTE (Etype (N), RE_Bignum));
4115 -- Construct call From Bignum
4118 Make_Function_Call (Loc,
4120 New_Occurrence_Of (RTE (RE_From_Bignum), Loc),
4121 Parameter_Associations => New_List (Relocate_Node (N)));
4122 end Convert_From_Bignum;
4124 -----------------------
4125 -- Convert_To_Bignum --
4126 -----------------------
4128 function Convert_To_Bignum (N : Node_Id) return Node_Id is
4129 Loc : constant Source_Ptr := Sloc (N);
4132 -- Nothing to do if Bignum already except call Relocate_Node
4134 if Is_RTE (Etype (N), RE_Bignum) then
4135 return Relocate_Node (N);
4137 -- Otherwise construct call to To_Bignum, converting the operand to the
4138 -- required Long_Long_Integer form.
4141 pragma Assert (Is_Signed_Integer_Type (Etype (N)));
4143 Make_Function_Call (Loc,
4145 New_Occurrence_Of (RTE (RE_To_Bignum), Loc),
4146 Parameter_Associations => New_List (
4147 Convert_To (Standard_Long_Long_Integer, Relocate_Node (N))));
4149 end Convert_To_Bignum;
4151 ---------------------
4152 -- Determine_Range --
4153 ---------------------
4155 Cache_Size : constant := 2 ** 10;
4156 type Cache_Index is range 0 .. Cache_Size - 1;
4157 -- Determine size of below cache (power of 2 is more efficient)
4159 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
4160 Determine_Range_Cache_V : array (Cache_Index) of Boolean;
4161 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
4162 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
4163 Determine_Range_Cache_Lo_R : array (Cache_Index) of Ureal;
4164 Determine_Range_Cache_Hi_R : array (Cache_Index) of Ureal;
4165 -- The above arrays are used to implement a small direct cache for
4166 -- Determine_Range and Determine_Range_R calls. Because of the way these
4167 -- subprograms recursively traces subexpressions, and because overflow
4168 -- checking calls the routine on the way up the tree, a quadratic behavior
4169 -- can otherwise be encountered in large expressions. The cache entry for
4170 -- node N is stored in the (N mod Cache_Size) entry, and can be validated
4171 -- by checking the actual node value stored there. The Range_Cache_V array
4172 -- records the setting of Assume_Valid for the cache entry.
4174 procedure Determine_Range
4179 Assume_Valid : Boolean := False)
4181 Typ : Entity_Id := Etype (N);
4182 -- Type to use, may get reset to base type for possibly invalid entity
4186 -- Lo and Hi bounds of left operand
4190 -- Lo and Hi bounds of right (or only) operand
4193 -- Temp variable used to hold a bound node
4196 -- High bound of base type of expression
4200 -- Refined values for low and high bounds, after tightening
4203 -- Used in lower level calls to indicate if call succeeded
4205 Cindex : Cache_Index;
4206 -- Used to search cache
4211 function OK_Operands return Boolean;
4212 -- Used for binary operators. Determines the ranges of the left and
4213 -- right operands, and if they are both OK, returns True, and puts
4214 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
4220 function OK_Operands return Boolean is
4223 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
4230 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4234 -- Start of processing for Determine_Range
4237 -- Prevent junk warnings by initializing range variables
4244 -- For temporary constants internally generated to remove side effects
4245 -- we must use the corresponding expression to determine the range of
4246 -- the expression. But note that the expander can also generate
4247 -- constants in other cases, including deferred constants.
4249 if Is_Entity_Name (N)
4250 and then Nkind (Parent (Entity (N))) = N_Object_Declaration
4251 and then Ekind (Entity (N)) = E_Constant
4252 and then Is_Internal_Name (Chars (Entity (N)))
4254 if Present (Expression (Parent (Entity (N)))) then
4256 (Expression (Parent (Entity (N))), OK, Lo, Hi, Assume_Valid);
4258 elsif Present (Full_View (Entity (N))) then
4260 (Expression (Parent (Full_View (Entity (N)))),
4261 OK, Lo, Hi, Assume_Valid);
4269 -- If type is not defined, we can't determine its range
4273 -- We don't deal with anything except discrete types
4275 or else not Is_Discrete_Type (Typ)
4277 -- Ignore type for which an error has been posted, since range in
4278 -- this case may well be a bogosity deriving from the error. Also
4279 -- ignore if error posted on the reference node.
4281 or else Error_Posted (N) or else Error_Posted (Typ)
4287 -- For all other cases, we can determine the range
4291 -- If value is compile time known, then the possible range is the one
4292 -- value that we know this expression definitely has.
4294 if Compile_Time_Known_Value (N) then
4295 Lo := Expr_Value (N);
4300 -- Return if already in the cache
4302 Cindex := Cache_Index (N mod Cache_Size);
4304 if Determine_Range_Cache_N (Cindex) = N
4306 Determine_Range_Cache_V (Cindex) = Assume_Valid
4308 Lo := Determine_Range_Cache_Lo (Cindex);
4309 Hi := Determine_Range_Cache_Hi (Cindex);
4313 -- Otherwise, start by finding the bounds of the type of the expression,
4314 -- the value cannot be outside this range (if it is, then we have an
4315 -- overflow situation, which is a separate check, we are talking here
4316 -- only about the expression value).
4318 -- First a check, never try to find the bounds of a generic type, since
4319 -- these bounds are always junk values, and it is only valid to look at
4320 -- the bounds in an instance.
4322 if Is_Generic_Type (Typ) then
4327 -- First step, change to use base type unless we know the value is valid
4329 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
4330 or else Assume_No_Invalid_Values
4331 or else Assume_Valid
4335 Typ := Underlying_Type (Base_Type (Typ));
4338 -- Retrieve the base type. Handle the case where the base type is a
4339 -- private enumeration type.
4341 Btyp := Base_Type (Typ);
4343 if Is_Private_Type (Btyp) and then Present (Full_View (Btyp)) then
4344 Btyp := Full_View (Btyp);
4347 -- We use the actual bound unless it is dynamic, in which case use the
4348 -- corresponding base type bound if possible. If we can't get a bound
4349 -- then we figure we can't determine the range (a peculiar case, that
4350 -- perhaps cannot happen, but there is no point in bombing in this
4351 -- optimization circuit.
4353 -- First the low bound
4355 Bound := Type_Low_Bound (Typ);
4357 if Compile_Time_Known_Value (Bound) then
4358 Lo := Expr_Value (Bound);
4360 elsif Compile_Time_Known_Value (Type_Low_Bound (Btyp)) then
4361 Lo := Expr_Value (Type_Low_Bound (Btyp));
4368 -- Now the high bound
4370 Bound := Type_High_Bound (Typ);
4372 -- We need the high bound of the base type later on, and this should
4373 -- always be compile time known. Again, it is not clear that this
4374 -- can ever be false, but no point in bombing.
4376 if Compile_Time_Known_Value (Type_High_Bound (Btyp)) then
4377 Hbound := Expr_Value (Type_High_Bound (Btyp));
4385 -- If we have a static subtype, then that may have a tighter bound so
4386 -- use the upper bound of the subtype instead in this case.
4388 if Compile_Time_Known_Value (Bound) then
4389 Hi := Expr_Value (Bound);
4392 -- We may be able to refine this value in certain situations. If any
4393 -- refinement is possible, then Lor and Hir are set to possibly tighter
4394 -- bounds, and OK1 is set to True.
4398 -- For unary plus, result is limited by range of operand
4402 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
4404 -- For unary minus, determine range of operand, and negate it
4408 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4415 -- For binary addition, get range of each operand and do the
4416 -- addition to get the result range.
4420 Lor := Lo_Left + Lo_Right;
4421 Hir := Hi_Left + Hi_Right;
4424 -- Division is tricky. The only case we consider is where the right
4425 -- operand is a positive constant, and in this case we simply divide
4426 -- the bounds of the left operand
4430 if Lo_Right = Hi_Right
4431 and then Lo_Right > 0
4433 Lor := Lo_Left / Lo_Right;
4434 Hir := Hi_Left / Lo_Right;
4440 -- For binary subtraction, get range of each operand and do the worst
4441 -- case subtraction to get the result range.
4443 when N_Op_Subtract =>
4445 Lor := Lo_Left - Hi_Right;
4446 Hir := Hi_Left - Lo_Right;
4449 -- For MOD, if right operand is a positive constant, then result must
4450 -- be in the allowable range of mod results.
4454 if Lo_Right = Hi_Right
4455 and then Lo_Right /= 0
4457 if Lo_Right > 0 then
4459 Hir := Lo_Right - 1;
4461 else -- Lo_Right < 0
4462 Lor := Lo_Right + 1;
4471 -- For REM, if right operand is a positive constant, then result must
4472 -- be in the allowable range of mod results.
4476 if Lo_Right = Hi_Right
4477 and then Lo_Right /= 0
4480 Dval : constant Uint := (abs Lo_Right) - 1;
4483 -- The sign of the result depends on the sign of the
4484 -- dividend (but not on the sign of the divisor, hence
4485 -- the abs operation above).
4505 -- Attribute reference cases
4507 when N_Attribute_Reference =>
4508 case Attribute_Name (N) is
4510 -- For Pos/Val attributes, we can refine the range using the
4511 -- possible range of values of the attribute expression.
4513 when Name_Pos | Name_Val =>
4515 (First (Expressions (N)), OK1, Lor, Hir, Assume_Valid);
4517 -- For Length attribute, use the bounds of the corresponding
4518 -- index type to refine the range.
4522 Atyp : Entity_Id := Etype (Prefix (N));
4530 if Is_Access_Type (Atyp) then
4531 Atyp := Designated_Type (Atyp);
4534 -- For string literal, we know exact value
4536 if Ekind (Atyp) = E_String_Literal_Subtype then
4538 Lo := String_Literal_Length (Atyp);
4539 Hi := String_Literal_Length (Atyp);
4543 -- Otherwise check for expression given
4545 if No (Expressions (N)) then
4549 UI_To_Int (Expr_Value (First (Expressions (N))));
4552 Indx := First_Index (Atyp);
4553 for J in 2 .. Inum loop
4554 Indx := Next_Index (Indx);
4557 -- If the index type is a formal type or derived from
4558 -- one, the bounds are not static.
4560 if Is_Generic_Type (Root_Type (Etype (Indx))) then
4566 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU,
4571 (Type_High_Bound (Etype (Indx)), OK1, UL, UU,
4576 -- The maximum value for Length is the biggest
4577 -- possible gap between the values of the bounds.
4578 -- But of course, this value cannot be negative.
4580 Hir := UI_Max (Uint_0, UU - LL + 1);
4582 -- For constrained arrays, the minimum value for
4583 -- Length is taken from the actual value of the
4584 -- bounds, since the index will be exactly of this
4587 if Is_Constrained (Atyp) then
4588 Lor := UI_Max (Uint_0, UL - LU + 1);
4590 -- For an unconstrained array, the minimum value
4591 -- for length is always zero.
4600 -- No special handling for other attributes
4601 -- Probably more opportunities exist here???
4608 -- For type conversion from one discrete type to another, we can
4609 -- refine the range using the converted value.
4611 when N_Type_Conversion =>
4612 Determine_Range (Expression (N), OK1, Lor, Hir, Assume_Valid);
4614 -- Nothing special to do for all other expression kinds
4622 -- At this stage, if OK1 is true, then we know that the actual result of
4623 -- the computed expression is in the range Lor .. Hir. We can use this
4624 -- to restrict the possible range of results.
4628 -- If the refined value of the low bound is greater than the type
4629 -- low bound, then reset it to the more restrictive value. However,
4630 -- we do NOT do this for the case of a modular type where the
4631 -- possible upper bound on the value is above the base type high
4632 -- bound, because that means the result could wrap.
4635 and then not (Is_Modular_Integer_Type (Typ) and then Hir > Hbound)
4640 -- Similarly, if the refined value of the high bound is less than the
4641 -- value so far, then reset it to the more restrictive value. Again,
4642 -- we do not do this if the refined low bound is negative for a
4643 -- modular type, since this would wrap.
4646 and then not (Is_Modular_Integer_Type (Typ) and then Lor < Uint_0)
4652 -- Set cache entry for future call and we are all done
4654 Determine_Range_Cache_N (Cindex) := N;
4655 Determine_Range_Cache_V (Cindex) := Assume_Valid;
4656 Determine_Range_Cache_Lo (Cindex) := Lo;
4657 Determine_Range_Cache_Hi (Cindex) := Hi;
4660 -- If any exception occurs, it means that we have some bug in the compiler,
4661 -- possibly triggered by a previous error, or by some unforeseen peculiar
4662 -- occurrence. However, this is only an optimization attempt, so there is
4663 -- really no point in crashing the compiler. Instead we just decide, too
4664 -- bad, we can't figure out a range in this case after all.
4669 -- Debug flag K disables this behavior (useful for debugging)
4671 if Debug_Flag_K then
4679 end Determine_Range;
4681 -----------------------
4682 -- Determine_Range_R --
4683 -----------------------
4685 procedure Determine_Range_R
4690 Assume_Valid : Boolean := False)
4692 Typ : Entity_Id := Etype (N);
4693 -- Type to use, may get reset to base type for possibly invalid entity
4697 -- Lo and Hi bounds of left operand
4701 -- Lo and Hi bounds of right (or only) operand
4704 -- Temp variable used to hold a bound node
4707 -- High bound of base type of expression
4711 -- Refined values for low and high bounds, after tightening
4714 -- Used in lower level calls to indicate if call succeeded
4716 Cindex : Cache_Index;
4717 -- Used to search cache
4722 function OK_Operands return Boolean;
4723 -- Used for binary operators. Determines the ranges of the left and
4724 -- right operands, and if they are both OK, returns True, and puts
4725 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
4727 function Round_Machine (B : Ureal) return Ureal;
4728 -- B is a real bound. Round it using mode Round_Even.
4734 function OK_Operands return Boolean is
4737 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
4744 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4752 function Round_Machine (B : Ureal) return Ureal is
4754 return Machine (Typ, B, Round_Even, N);
4757 -- Start of processing for Determine_Range_R
4760 -- Prevent junk warnings by initializing range variables
4767 -- For temporary constants internally generated to remove side effects
4768 -- we must use the corresponding expression to determine the range of
4769 -- the expression. But note that the expander can also generate
4770 -- constants in other cases, including deferred constants.
4772 if Is_Entity_Name (N)
4773 and then Nkind (Parent (Entity (N))) = N_Object_Declaration
4774 and then Ekind (Entity (N)) = E_Constant
4775 and then Is_Internal_Name (Chars (Entity (N)))
4777 if Present (Expression (Parent (Entity (N)))) then
4779 (Expression (Parent (Entity (N))), OK, Lo, Hi, Assume_Valid);
4781 elsif Present (Full_View (Entity (N))) then
4783 (Expression (Parent (Full_View (Entity (N)))),
4784 OK, Lo, Hi, Assume_Valid);
4793 -- If type is not defined, we can't determine its range
4797 -- We don't deal with anything except IEEE floating-point types
4799 or else not Is_Floating_Point_Type (Typ)
4800 or else Float_Rep (Typ) /= IEEE_Binary
4802 -- Ignore type for which an error has been posted, since range in
4803 -- this case may well be a bogosity deriving from the error. Also
4804 -- ignore if error posted on the reference node.
4806 or else Error_Posted (N) or else Error_Posted (Typ)
4812 -- For all other cases, we can determine the range
4816 -- If value is compile time known, then the possible range is the one
4817 -- value that we know this expression definitely has.
4819 if Compile_Time_Known_Value (N) then
4820 Lo := Expr_Value_R (N);
4825 -- Return if already in the cache
4827 Cindex := Cache_Index (N mod Cache_Size);
4829 if Determine_Range_Cache_N (Cindex) = N
4831 Determine_Range_Cache_V (Cindex) = Assume_Valid
4833 Lo := Determine_Range_Cache_Lo_R (Cindex);
4834 Hi := Determine_Range_Cache_Hi_R (Cindex);
4838 -- Otherwise, start by finding the bounds of the type of the expression,
4839 -- the value cannot be outside this range (if it is, then we have an
4840 -- overflow situation, which is a separate check, we are talking here
4841 -- only about the expression value).
4843 -- First a check, never try to find the bounds of a generic type, since
4844 -- these bounds are always junk values, and it is only valid to look at
4845 -- the bounds in an instance.
4847 if Is_Generic_Type (Typ) then
4852 -- First step, change to use base type unless we know the value is valid
4854 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
4855 or else Assume_No_Invalid_Values
4856 or else Assume_Valid
4860 Typ := Underlying_Type (Base_Type (Typ));
4863 -- Retrieve the base type. Handle the case where the base type is a
4866 Btyp := Base_Type (Typ);
4868 if Is_Private_Type (Btyp) and then Present (Full_View (Btyp)) then
4869 Btyp := Full_View (Btyp);
4872 -- We use the actual bound unless it is dynamic, in which case use the
4873 -- corresponding base type bound if possible. If we can't get a bound
4874 -- then we figure we can't determine the range (a peculiar case, that
4875 -- perhaps cannot happen, but there is no point in bombing in this
4876 -- optimization circuit).
4878 -- First the low bound
4880 Bound := Type_Low_Bound (Typ);
4882 if Compile_Time_Known_Value (Bound) then
4883 Lo := Expr_Value_R (Bound);
4885 elsif Compile_Time_Known_Value (Type_Low_Bound (Btyp)) then
4886 Lo := Expr_Value_R (Type_Low_Bound (Btyp));
4893 -- Now the high bound
4895 Bound := Type_High_Bound (Typ);
4897 -- We need the high bound of the base type later on, and this should
4898 -- always be compile time known. Again, it is not clear that this
4899 -- can ever be false, but no point in bombing.
4901 if Compile_Time_Known_Value (Type_High_Bound (Btyp)) then
4902 Hbound := Expr_Value_R (Type_High_Bound (Btyp));
4910 -- If we have a static subtype, then that may have a tighter bound so
4911 -- use the upper bound of the subtype instead in this case.
4913 if Compile_Time_Known_Value (Bound) then
4914 Hi := Expr_Value_R (Bound);
4917 -- We may be able to refine this value in certain situations. If any
4918 -- refinement is possible, then Lor and Hir are set to possibly tighter
4919 -- bounds, and OK1 is set to True.
4923 -- For unary plus, result is limited by range of operand
4927 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
4929 -- For unary minus, determine range of operand, and negate it
4933 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4940 -- For binary addition, get range of each operand and do the
4941 -- addition to get the result range.
4945 Lor := Round_Machine (Lo_Left + Lo_Right);
4946 Hir := Round_Machine (Hi_Left + Hi_Right);
4949 -- For binary subtraction, get range of each operand and do the worst
4950 -- case subtraction to get the result range.
4952 when N_Op_Subtract =>
4954 Lor := Round_Machine (Lo_Left - Hi_Right);
4955 Hir := Round_Machine (Hi_Left - Lo_Right);
4958 -- For multiplication, get range of each operand and do the
4959 -- four multiplications to get the result range.
4961 when N_Op_Multiply =>
4964 M1 : constant Ureal := Round_Machine (Lo_Left * Lo_Right);
4965 M2 : constant Ureal := Round_Machine (Lo_Left * Hi_Right);
4966 M3 : constant Ureal := Round_Machine (Hi_Left * Lo_Right);
4967 M4 : constant Ureal := Round_Machine (Hi_Left * Hi_Right);
4969 Lor := UR_Min (UR_Min (M1, M2), UR_Min (M3, M4));
4970 Hir := UR_Max (UR_Max (M1, M2), UR_Max (M3, M4));
4974 -- For division, consider separately the cases where the right
4975 -- operand is positive or negative. Otherwise, the right operand
4976 -- can be arbitrarily close to zero, so the result is likely to
4977 -- be unbounded in one direction, do not attempt to compute it.
4982 -- Right operand is positive
4984 if Lo_Right > Ureal_0 then
4986 -- If the low bound of the left operand is negative, obtain
4987 -- the overall low bound by dividing it by the smallest
4988 -- value of the right operand, and otherwise by the largest
4989 -- value of the right operand.
4991 if Lo_Left < Ureal_0 then
4992 Lor := Round_Machine (Lo_Left / Lo_Right);
4994 Lor := Round_Machine (Lo_Left / Hi_Right);
4997 -- If the high bound of the left operand is negative, obtain
4998 -- the overall high bound by dividing it by the largest
4999 -- value of the right operand, and otherwise by the
5000 -- smallest value of the right operand.
5002 if Hi_Left < Ureal_0 then
5003 Hir := Round_Machine (Hi_Left / Hi_Right);
5005 Hir := Round_Machine (Hi_Left / Lo_Right);
5008 -- Right operand is negative
5010 elsif Hi_Right < Ureal_0 then
5012 -- If the low bound of the left operand is negative, obtain
5013 -- the overall low bound by dividing it by the largest
5014 -- value of the right operand, and otherwise by the smallest
5015 -- value of the right operand.
5017 if Lo_Left < Ureal_0 then
5018 Lor := Round_Machine (Lo_Left / Hi_Right);
5020 Lor := Round_Machine (Lo_Left / Lo_Right);
5023 -- If the high bound of the left operand is negative, obtain
5024 -- the overall high bound by dividing it by the smallest
5025 -- value of the right operand, and otherwise by the
5026 -- largest value of the right operand.
5028 if Hi_Left < Ureal_0 then
5029 Hir := Round_Machine (Hi_Left / Lo_Right);
5031 Hir := Round_Machine (Hi_Left / Hi_Right);
5039 -- For type conversion from one floating-point type to another, we
5040 -- can refine the range using the converted value.
5042 when N_Type_Conversion =>
5043 Determine_Range_R (Expression (N), OK1, Lor, Hir, Assume_Valid);
5045 -- Nothing special to do for all other expression kinds
5053 -- At this stage, if OK1 is true, then we know that the actual result of
5054 -- the computed expression is in the range Lor .. Hir. We can use this
5055 -- to restrict the possible range of results.
5059 -- If the refined value of the low bound is greater than the type
5060 -- low bound, then reset it to the more restrictive value.
5066 -- Similarly, if the refined value of the high bound is less than the
5067 -- value so far, then reset it to the more restrictive value.
5074 -- Set cache entry for future call and we are all done
5076 Determine_Range_Cache_N (Cindex) := N;
5077 Determine_Range_Cache_V (Cindex) := Assume_Valid;
5078 Determine_Range_Cache_Lo_R (Cindex) := Lo;
5079 Determine_Range_Cache_Hi_R (Cindex) := Hi;
5082 -- If any exception occurs, it means that we have some bug in the compiler,
5083 -- possibly triggered by a previous error, or by some unforeseen peculiar
5084 -- occurrence. However, this is only an optimization attempt, so there is
5085 -- really no point in crashing the compiler. Instead we just decide, too
5086 -- bad, we can't figure out a range in this case after all.
5091 -- Debug flag K disables this behavior (useful for debugging)
5093 if Debug_Flag_K then
5101 end Determine_Range_R;
5103 ------------------------------------
5104 -- Discriminant_Checks_Suppressed --
5105 ------------------------------------
5107 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
5110 if Is_Unchecked_Union (E) then
5112 elsif Checks_May_Be_Suppressed (E) then
5113 return Is_Check_Suppressed (E, Discriminant_Check);
5117 return Scope_Suppress.Suppress (Discriminant_Check);
5118 end Discriminant_Checks_Suppressed;
5120 --------------------------------
5121 -- Division_Checks_Suppressed --
5122 --------------------------------
5124 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
5126 if Present (E) and then Checks_May_Be_Suppressed (E) then
5127 return Is_Check_Suppressed (E, Division_Check);
5129 return Scope_Suppress.Suppress (Division_Check);
5131 end Division_Checks_Suppressed;
5133 --------------------------------------
5134 -- Duplicated_Tag_Checks_Suppressed --
5135 --------------------------------------
5137 function Duplicated_Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
5139 if Present (E) and then Checks_May_Be_Suppressed (E) then
5140 return Is_Check_Suppressed (E, Duplicated_Tag_Check);
5142 return Scope_Suppress.Suppress (Duplicated_Tag_Check);
5144 end Duplicated_Tag_Checks_Suppressed;
5146 -----------------------------------
5147 -- Elaboration_Checks_Suppressed --
5148 -----------------------------------
5150 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
5152 -- The complication in this routine is that if we are in the dynamic
5153 -- model of elaboration, we also check All_Checks, since All_Checks
5154 -- does not set Elaboration_Check explicitly.
5157 if Kill_Elaboration_Checks (E) then
5160 elsif Checks_May_Be_Suppressed (E) then
5161 if Is_Check_Suppressed (E, Elaboration_Check) then
5163 elsif Dynamic_Elaboration_Checks then
5164 return Is_Check_Suppressed (E, All_Checks);
5171 if Scope_Suppress.Suppress (Elaboration_Check) then
5173 elsif Dynamic_Elaboration_Checks then
5174 return Scope_Suppress.Suppress (All_Checks);
5178 end Elaboration_Checks_Suppressed;
5180 ---------------------------
5181 -- Enable_Overflow_Check --
5182 ---------------------------
5184 procedure Enable_Overflow_Check (N : Node_Id) is
5185 Typ : constant Entity_Id := Base_Type (Etype (N));
5186 Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
5194 Do_Ovflow_Check : Boolean;
5197 if Debug_Flag_CC then
5198 w ("Enable_Overflow_Check for node ", Int (N));
5199 Write_Str (" Source location = ");
5204 -- No check if overflow checks suppressed for type of node
5206 if Overflow_Checks_Suppressed (Etype (N)) then
5209 -- Nothing to do for unsigned integer types, which do not overflow
5211 elsif Is_Modular_Integer_Type (Typ) then
5215 -- This is the point at which processing for STRICT mode diverges
5216 -- from processing for MINIMIZED/ELIMINATED modes. This divergence is
5217 -- probably more extreme that it needs to be, but what is going on here
5218 -- is that when we introduced MINIMIZED/ELIMINATED modes, we wanted
5219 -- to leave the processing for STRICT mode untouched. There were
5220 -- two reasons for this. First it avoided any incompatible change of
5221 -- behavior. Second, it guaranteed that STRICT mode continued to be
5224 -- The big difference is that in STRICT mode there is a fair amount of
5225 -- circuitry to try to avoid setting the Do_Overflow_Check flag if we
5226 -- know that no check is needed. We skip all that in the two new modes,
5227 -- since really overflow checking happens over a whole subtree, and we
5228 -- do the corresponding optimizations later on when applying the checks.
5230 if Mode in Minimized_Or_Eliminated then
5231 if not (Overflow_Checks_Suppressed (Etype (N)))
5232 and then not (Is_Entity_Name (N)
5233 and then Overflow_Checks_Suppressed (Entity (N)))
5235 Activate_Overflow_Check (N);
5238 if Debug_Flag_CC then
5239 w ("Minimized/Eliminated mode");
5245 -- Remainder of processing is for STRICT case, and is unchanged from
5246 -- earlier versions preceding the addition of MINIMIZED/ELIMINATED.
5248 -- Nothing to do if the range of the result is known OK. We skip this
5249 -- for conversions, since the caller already did the check, and in any
5250 -- case the condition for deleting the check for a type conversion is
5253 if Nkind (N) /= N_Type_Conversion then
5254 Determine_Range (N, OK, Lo, Hi, Assume_Valid => True);
5256 -- Note in the test below that we assume that the range is not OK
5257 -- if a bound of the range is equal to that of the type. That's not
5258 -- quite accurate but we do this for the following reasons:
5260 -- a) The way that Determine_Range works, it will typically report
5261 -- the bounds of the value as being equal to the bounds of the
5262 -- type, because it either can't tell anything more precise, or
5263 -- does not think it is worth the effort to be more precise.
5265 -- b) It is very unusual to have a situation in which this would
5266 -- generate an unnecessary overflow check (an example would be
5267 -- a subtype with a range 0 .. Integer'Last - 1 to which the
5268 -- literal value one is added).
5270 -- c) The alternative is a lot of special casing in this routine
5271 -- which would partially duplicate Determine_Range processing.
5274 Do_Ovflow_Check := True;
5276 -- Note that the following checks are quite deliberately > and <
5277 -- rather than >= and <= as explained above.
5279 if Lo > Expr_Value (Type_Low_Bound (Typ))
5281 Hi < Expr_Value (Type_High_Bound (Typ))
5283 Do_Ovflow_Check := False;
5285 -- Despite the comments above, it is worth dealing specially with
5286 -- division specially. The only case where integer division can
5287 -- overflow is (largest negative number) / (-1). So we will do
5288 -- an extra range analysis to see if this is possible.
5290 elsif Nkind (N) = N_Op_Divide then
5292 (Left_Opnd (N), OK, Lo, Hi, Assume_Valid => True);
5294 if OK and then Lo > Expr_Value (Type_Low_Bound (Typ)) then
5295 Do_Ovflow_Check := False;
5299 (Right_Opnd (N), OK, Lo, Hi, Assume_Valid => True);
5301 if OK and then (Lo > Uint_Minus_1
5305 Do_Ovflow_Check := False;
5310 -- If no overflow check required, we are done
5312 if not Do_Ovflow_Check then
5313 if Debug_Flag_CC then
5314 w ("No overflow check required");
5322 -- If not in optimizing mode, set flag and we are done. We are also done
5323 -- (and just set the flag) if the type is not a discrete type, since it
5324 -- is not worth the effort to eliminate checks for other than discrete
5325 -- types. In addition, we take this same path if we have stored the
5326 -- maximum number of checks possible already (a very unlikely situation,
5327 -- but we do not want to blow up).
5329 if Optimization_Level = 0
5330 or else not Is_Discrete_Type (Etype (N))
5331 or else Num_Saved_Checks = Saved_Checks'Last
5333 Activate_Overflow_Check (N);
5335 if Debug_Flag_CC then
5336 w ("Optimization off");
5342 -- Otherwise evaluate and check the expression
5347 Target_Type => Empty,
5353 if Debug_Flag_CC then
5354 w ("Called Find_Check");
5358 w (" Check_Num = ", Chk);
5359 w (" Ent = ", Int (Ent));
5360 Write_Str (" Ofs = ");
5365 -- If check is not of form to optimize, then set flag and we are done
5368 Activate_Overflow_Check (N);
5372 -- If check is already performed, then return without setting flag
5375 if Debug_Flag_CC then
5376 w ("Check suppressed!");
5382 -- Here we will make a new entry for the new check
5384 Activate_Overflow_Check (N);
5385 Num_Saved_Checks := Num_Saved_Checks + 1;
5386 Saved_Checks (Num_Saved_Checks) :=
5391 Target_Type => Empty);
5393 if Debug_Flag_CC then
5394 w ("Make new entry, check number = ", Num_Saved_Checks);
5395 w (" Entity = ", Int (Ent));
5396 Write_Str (" Offset = ");
5398 w (" Check_Type = O");
5399 w (" Target_Type = Empty");
5402 -- If we get an exception, then something went wrong, probably because of
5403 -- an error in the structure of the tree due to an incorrect program. Or
5404 -- it may be a bug in the optimization circuit. In either case the safest
5405 -- thing is simply to set the check flag unconditionally.
5409 Activate_Overflow_Check (N);
5411 if Debug_Flag_CC then
5412 w (" exception occurred, overflow flag set");
5416 end Enable_Overflow_Check;
5418 ------------------------
5419 -- Enable_Range_Check --
5420 ------------------------
5422 procedure Enable_Range_Check (N : Node_Id) is
5431 -- Return if unchecked type conversion with range check killed. In this
5432 -- case we never set the flag (that's what Kill_Range_Check is about).
5434 if Nkind (N) = N_Unchecked_Type_Conversion
5435 and then Kill_Range_Check (N)
5440 -- Do not set range check flag if parent is assignment statement or
5441 -- object declaration with Suppress_Assignment_Checks flag set
5443 if Nkind_In (Parent (N), N_Assignment_Statement, N_Object_Declaration)
5444 and then Suppress_Assignment_Checks (Parent (N))
5449 -- Check for various cases where we should suppress the range check
5451 -- No check if range checks suppressed for type of node
5453 if Present (Etype (N)) and then Range_Checks_Suppressed (Etype (N)) then
5456 -- No check if node is an entity name, and range checks are suppressed
5457 -- for this entity, or for the type of this entity.
5459 elsif Is_Entity_Name (N)
5460 and then (Range_Checks_Suppressed (Entity (N))
5461 or else Range_Checks_Suppressed (Etype (Entity (N))))
5465 -- No checks if index of array, and index checks are suppressed for
5466 -- the array object or the type of the array.
5468 elsif Nkind (Parent (N)) = N_Indexed_Component then
5470 Pref : constant Node_Id := Prefix (Parent (N));
5472 if Is_Entity_Name (Pref)
5473 and then Index_Checks_Suppressed (Entity (Pref))
5476 elsif Index_Checks_Suppressed (Etype (Pref)) then
5482 -- Debug trace output
5484 if Debug_Flag_CC then
5485 w ("Enable_Range_Check for node ", Int (N));
5486 Write_Str (" Source location = ");
5491 -- If not in optimizing mode, set flag and we are done. We are also done
5492 -- (and just set the flag) if the type is not a discrete type, since it
5493 -- is not worth the effort to eliminate checks for other than discrete
5494 -- types. In addition, we take this same path if we have stored the
5495 -- maximum number of checks possible already (a very unlikely situation,
5496 -- but we do not want to blow up).
5498 if Optimization_Level = 0
5499 or else No (Etype (N))
5500 or else not Is_Discrete_Type (Etype (N))
5501 or else Num_Saved_Checks = Saved_Checks'Last
5503 Activate_Range_Check (N);
5505 if Debug_Flag_CC then
5506 w ("Optimization off");
5512 -- Otherwise find out the target type
5516 -- For assignment, use left side subtype
5518 if Nkind (P) = N_Assignment_Statement
5519 and then Expression (P) = N
5521 Ttyp := Etype (Name (P));
5523 -- For indexed component, use subscript subtype
5525 elsif Nkind (P) = N_Indexed_Component then
5532 Atyp := Etype (Prefix (P));
5534 if Is_Access_Type (Atyp) then
5535 Atyp := Designated_Type (Atyp);
5537 -- If the prefix is an access to an unconstrained array,
5538 -- perform check unconditionally: it depends on the bounds of
5539 -- an object and we cannot currently recognize whether the test
5540 -- may be redundant.
5542 if not Is_Constrained (Atyp) then
5543 Activate_Range_Check (N);
5547 -- Ditto if prefix is simply an unconstrained array. We used
5548 -- to think this case was OK, if the prefix was not an explicit
5549 -- dereference, but we have now seen a case where this is not
5550 -- true, so it is safer to just suppress the optimization in this
5551 -- case. The back end is getting better at eliminating redundant
5552 -- checks in any case, so the loss won't be important.
5554 elsif Is_Array_Type (Atyp)
5555 and then not Is_Constrained (Atyp)
5557 Activate_Range_Check (N);
5561 Indx := First_Index (Atyp);
5562 Subs := First (Expressions (P));
5565 Ttyp := Etype (Indx);
5574 -- For now, ignore all other cases, they are not so interesting
5577 if Debug_Flag_CC then
5578 w (" target type not found, flag set");
5581 Activate_Range_Check (N);
5585 -- Evaluate and check the expression
5590 Target_Type => Ttyp,
5596 if Debug_Flag_CC then
5597 w ("Called Find_Check");
5598 w ("Target_Typ = ", Int (Ttyp));
5602 w (" Check_Num = ", Chk);
5603 w (" Ent = ", Int (Ent));
5604 Write_Str (" Ofs = ");
5609 -- If check is not of form to optimize, then set flag and we are done
5612 if Debug_Flag_CC then
5613 w (" expression not of optimizable type, flag set");
5616 Activate_Range_Check (N);
5620 -- If check is already performed, then return without setting flag
5623 if Debug_Flag_CC then
5624 w ("Check suppressed!");
5630 -- Here we will make a new entry for the new check
5632 Activate_Range_Check (N);
5633 Num_Saved_Checks := Num_Saved_Checks + 1;
5634 Saved_Checks (Num_Saved_Checks) :=
5639 Target_Type => Ttyp);
5641 if Debug_Flag_CC then
5642 w ("Make new entry, check number = ", Num_Saved_Checks);
5643 w (" Entity = ", Int (Ent));
5644 Write_Str (" Offset = ");
5646 w (" Check_Type = R");
5647 w (" Target_Type = ", Int (Ttyp));
5648 pg (Union_Id (Ttyp));
5651 -- If we get an exception, then something went wrong, probably because of
5652 -- an error in the structure of the tree due to an incorrect program. Or
5653 -- it may be a bug in the optimization circuit. In either case the safest
5654 -- thing is simply to set the check flag unconditionally.
5658 Activate_Range_Check (N);
5660 if Debug_Flag_CC then
5661 w (" exception occurred, range flag set");
5665 end Enable_Range_Check;
5671 procedure Ensure_Valid
5673 Holes_OK : Boolean := False;
5674 Related_Id : Entity_Id := Empty;
5675 Is_Low_Bound : Boolean := False;
5676 Is_High_Bound : Boolean := False)
5678 Typ : constant Entity_Id := Etype (Expr);
5681 -- Ignore call if we are not doing any validity checking
5683 if not Validity_Checks_On then
5686 -- Ignore call if range or validity checks suppressed on entity or type
5688 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
5691 -- No check required if expression is from the expander, we assume the
5692 -- expander will generate whatever checks are needed. Note that this is
5693 -- not just an optimization, it avoids infinite recursions.
5695 -- Unchecked conversions must be checked, unless they are initialized
5696 -- scalar values, as in a component assignment in an init proc.
5698 -- In addition, we force a check if Force_Validity_Checks is set
5700 elsif not Comes_From_Source (Expr)
5701 and then not Force_Validity_Checks
5702 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
5703 or else Kill_Range_Check (Expr))
5707 -- No check required if expression is known to have valid value
5709 elsif Expr_Known_Valid (Expr) then
5712 -- No check needed within a generated predicate function. Validity
5713 -- of input value will have been checked earlier.
5715 elsif Ekind (Current_Scope) = E_Function
5716 and then Is_Predicate_Function (Current_Scope)
5720 -- Ignore case of enumeration with holes where the flag is set not to
5721 -- worry about holes, since no special validity check is needed
5723 elsif Is_Enumeration_Type (Typ)
5724 and then Has_Non_Standard_Rep (Typ)
5729 -- No check required on the left-hand side of an assignment
5731 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
5732 and then Expr = Name (Parent (Expr))
5736 -- No check on a universal real constant. The context will eventually
5737 -- convert it to a machine number for some target type, or report an
5740 elsif Nkind (Expr) = N_Real_Literal
5741 and then Etype (Expr) = Universal_Real
5745 -- If the expression denotes a component of a packed boolean array,
5746 -- no possible check applies. We ignore the old ACATS chestnuts that
5747 -- involve Boolean range True..True.
5749 -- Note: validity checks are generated for expressions that yield a
5750 -- scalar type, when it is possible to create a value that is outside of
5751 -- the type. If this is a one-bit boolean no such value exists. This is
5752 -- an optimization, and it also prevents compiler blowing up during the
5753 -- elaboration of improperly expanded packed array references.
5755 elsif Nkind (Expr) = N_Indexed_Component
5756 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
5757 and then Root_Type (Etype (Expr)) = Standard_Boolean
5761 -- For an expression with actions, we want to insert the validity check
5762 -- on the final Expression.
5764 elsif Nkind (Expr) = N_Expression_With_Actions then
5765 Ensure_Valid (Expression (Expr));
5768 -- An annoying special case. If this is an out parameter of a scalar
5769 -- type, then the value is not going to be accessed, therefore it is
5770 -- inappropriate to do any validity check at the call site.
5773 -- Only need to worry about scalar types
5775 if Is_Scalar_Type (Typ) then
5785 -- Find actual argument (which may be a parameter association)
5786 -- and the parent of the actual argument (the call statement)
5791 if Nkind (P) = N_Parameter_Association then
5796 -- Only need to worry if we are argument of a procedure call
5797 -- since functions don't have out parameters. If this is an
5798 -- indirect or dispatching call, get signature from the
5801 if Nkind (P) = N_Procedure_Call_Statement then
5802 L := Parameter_Associations (P);
5804 if Is_Entity_Name (Name (P)) then
5805 E := Entity (Name (P));
5807 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
5808 E := Etype (Name (P));
5811 -- Only need to worry if there are indeed actuals, and if
5812 -- this could be a procedure call, otherwise we cannot get a
5813 -- match (either we are not an argument, or the mode of the
5814 -- formal is not OUT). This test also filters out the
5817 if Is_Non_Empty_List (L) and then Is_Subprogram (E) then
5819 -- This is the loop through parameters, looking for an
5820 -- OUT parameter for which we are the argument.
5822 F := First_Formal (E);
5824 while Present (F) loop
5825 if Ekind (F) = E_Out_Parameter and then A = N then
5838 -- If this is a boolean expression, only its elementary operands need
5839 -- checking: if they are valid, a boolean or short-circuit operation
5840 -- with them will be valid as well.
5842 if Base_Type (Typ) = Standard_Boolean
5844 (Nkind (Expr) in N_Op or else Nkind (Expr) in N_Short_Circuit)
5849 -- If we fall through, a validity check is required
5851 Insert_Valid_Check (Expr, Related_Id, Is_Low_Bound, Is_High_Bound);
5853 if Is_Entity_Name (Expr)
5854 and then Safe_To_Capture_Value (Expr, Entity (Expr))
5856 Set_Is_Known_Valid (Entity (Expr));
5860 ----------------------
5861 -- Expr_Known_Valid --
5862 ----------------------
5864 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
5865 Typ : constant Entity_Id := Etype (Expr);
5868 -- Non-scalar types are always considered valid, since they never give
5869 -- rise to the issues of erroneous or bounded error behavior that are
5870 -- the concern. In formal reference manual terms the notion of validity
5871 -- only applies to scalar types. Note that even when packed arrays are
5872 -- represented using modular types, they are still arrays semantically,
5873 -- so they are also always valid (in particular, the unused bits can be
5874 -- random rubbish without affecting the validity of the array value).
5876 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Impl_Type (Typ) then
5879 -- If no validity checking, then everything is considered valid
5881 elsif not Validity_Checks_On then
5884 -- Floating-point types are considered valid unless floating-point
5885 -- validity checks have been specifically turned on.
5887 elsif Is_Floating_Point_Type (Typ)
5888 and then not Validity_Check_Floating_Point
5892 -- If the expression is the value of an object that is known to be
5893 -- valid, then clearly the expression value itself is valid.
5895 elsif Is_Entity_Name (Expr)
5896 and then Is_Known_Valid (Entity (Expr))
5898 -- Exclude volatile variables
5900 and then not Treat_As_Volatile (Entity (Expr))
5904 -- References to discriminants are always considered valid. The value
5905 -- of a discriminant gets checked when the object is built. Within the
5906 -- record, we consider it valid, and it is important to do so, since
5907 -- otherwise we can try to generate bogus validity checks which
5908 -- reference discriminants out of scope. Discriminants of concurrent
5909 -- types are excluded for the same reason.
5911 elsif Is_Entity_Name (Expr)
5912 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
5916 -- If the type is one for which all values are known valid, then we are
5917 -- sure that the value is valid except in the slightly odd case where
5918 -- the expression is a reference to a variable whose size has been
5919 -- explicitly set to a value greater than the object size.
5921 elsif Is_Known_Valid (Typ) then
5922 if Is_Entity_Name (Expr)
5923 and then Ekind (Entity (Expr)) = E_Variable
5924 and then Esize (Entity (Expr)) > Esize (Typ)
5931 -- Integer and character literals always have valid values, where
5932 -- appropriate these will be range checked in any case.
5934 elsif Nkind_In (Expr, N_Integer_Literal, N_Character_Literal) then
5937 -- If we have a type conversion or a qualification of a known valid
5938 -- value, then the result will always be valid.
5940 elsif Nkind_In (Expr, N_Type_Conversion, N_Qualified_Expression) then
5941 return Expr_Known_Valid (Expression (Expr));
5943 -- Case of expression is a non-floating-point operator. In this case we
5944 -- can assume the result is valid the generated code for the operator
5945 -- will include whatever checks are needed (e.g. range checks) to ensure
5946 -- validity. This assumption does not hold for the floating-point case,
5947 -- since floating-point operators can generate Infinite or NaN results
5948 -- which are considered invalid.
5950 -- Historical note: in older versions, the exemption of floating-point
5951 -- types from this assumption was done only in cases where the parent
5952 -- was an assignment, function call or parameter association. Presumably
5953 -- the idea was that in other contexts, the result would be checked
5954 -- elsewhere, but this list of cases was missing tests (at least the
5955 -- N_Object_Declaration case, as shown by a reported missing validity
5956 -- check), and it is not clear why function calls but not procedure
5957 -- calls were tested for. It really seems more accurate and much
5958 -- safer to recognize that expressions which are the result of a
5959 -- floating-point operator can never be assumed to be valid.
5961 elsif Nkind (Expr) in N_Op and then not Is_Floating_Point_Type (Typ) then
5964 -- The result of a membership test is always valid, since it is true or
5965 -- false, there are no other possibilities.
5967 elsif Nkind (Expr) in N_Membership_Test then
5970 -- For all other cases, we do not know the expression is valid
5975 end Expr_Known_Valid;
5981 procedure Find_Check
5983 Check_Type : Character;
5984 Target_Type : Entity_Id;
5985 Entry_OK : out Boolean;
5986 Check_Num : out Nat;
5987 Ent : out Entity_Id;
5990 function Within_Range_Of
5991 (Target_Type : Entity_Id;
5992 Check_Type : Entity_Id) return Boolean;
5993 -- Given a requirement for checking a range against Target_Type, and
5994 -- and a range Check_Type against which a check has already been made,
5995 -- determines if the check against check type is sufficient to ensure
5996 -- that no check against Target_Type is required.
5998 ---------------------
5999 -- Within_Range_Of --
6000 ---------------------
6002 function Within_Range_Of
6003 (Target_Type : Entity_Id;
6004 Check_Type : Entity_Id) return Boolean
6007 if Target_Type = Check_Type then
6012 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
6013 Thi : constant Node_Id := Type_High_Bound (Target_Type);
6014 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
6015 Chi : constant Node_Id := Type_High_Bound (Check_Type);
6019 or else (Compile_Time_Known_Value (Tlo)
6021 Compile_Time_Known_Value (Clo)
6023 Expr_Value (Clo) >= Expr_Value (Tlo)))
6026 or else (Compile_Time_Known_Value (Thi)
6028 Compile_Time_Known_Value (Chi)
6030 Expr_Value (Chi) <= Expr_Value (Clo)))
6038 end Within_Range_Of;
6040 -- Start of processing for Find_Check
6043 -- Establish default, in case no entry is found
6047 -- Case of expression is simple entity reference
6049 if Is_Entity_Name (Expr) then
6050 Ent := Entity (Expr);
6053 -- Case of expression is entity + known constant
6055 elsif Nkind (Expr) = N_Op_Add
6056 and then Compile_Time_Known_Value (Right_Opnd (Expr))
6057 and then Is_Entity_Name (Left_Opnd (Expr))
6059 Ent := Entity (Left_Opnd (Expr));
6060 Ofs := Expr_Value (Right_Opnd (Expr));
6062 -- Case of expression is entity - known constant
6064 elsif Nkind (Expr) = N_Op_Subtract
6065 and then Compile_Time_Known_Value (Right_Opnd (Expr))
6066 and then Is_Entity_Name (Left_Opnd (Expr))
6068 Ent := Entity (Left_Opnd (Expr));
6069 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
6071 -- Any other expression is not of the right form
6080 -- Come here with expression of appropriate form, check if entity is an
6081 -- appropriate one for our purposes.
6083 if (Ekind (Ent) = E_Variable
6084 or else Is_Constant_Object (Ent))
6085 and then not Is_Library_Level_Entity (Ent)
6093 -- See if there is matching check already
6095 for J in reverse 1 .. Num_Saved_Checks loop
6097 SC : Saved_Check renames Saved_Checks (J);
6099 if SC.Killed = False
6100 and then SC.Entity = Ent
6101 and then SC.Offset = Ofs
6102 and then SC.Check_Type = Check_Type
6103 and then Within_Range_Of (Target_Type, SC.Target_Type)
6111 -- If we fall through entry was not found
6116 ---------------------------------
6117 -- Generate_Discriminant_Check --
6118 ---------------------------------
6120 -- Note: the code for this procedure is derived from the
6121 -- Emit_Discriminant_Check Routine in trans.c.
6123 procedure Generate_Discriminant_Check (N : Node_Id) is
6124 Loc : constant Source_Ptr := Sloc (N);
6125 Pref : constant Node_Id := Prefix (N);
6126 Sel : constant Node_Id := Selector_Name (N);
6128 Orig_Comp : constant Entity_Id :=
6129 Original_Record_Component (Entity (Sel));
6130 -- The original component to be checked
6132 Discr_Fct : constant Entity_Id :=
6133 Discriminant_Checking_Func (Orig_Comp);
6134 -- The discriminant checking function
6137 -- One discriminant to be checked in the type
6139 Real_Discr : Entity_Id;
6140 -- Actual discriminant in the call
6142 Pref_Type : Entity_Id;
6143 -- Type of relevant prefix (ignoring private/access stuff)
6146 -- List of arguments for function call
6149 -- Keep track of the formal corresponding to the actual we build for
6150 -- each discriminant, in order to be able to perform the necessary type
6154 -- Selected component reference for checking function argument
6157 Pref_Type := Etype (Pref);
6159 -- Force evaluation of the prefix, so that it does not get evaluated
6160 -- twice (once for the check, once for the actual reference). Such a
6161 -- double evaluation is always a potential source of inefficiency, and
6162 -- is functionally incorrect in the volatile case, or when the prefix
6163 -- may have side effects. A nonvolatile entity or a component of a
6164 -- nonvolatile entity requires no evaluation.
6166 if Is_Entity_Name (Pref) then
6167 if Treat_As_Volatile (Entity (Pref)) then
6168 Force_Evaluation (Pref, Name_Req => True);
6171 elsif Treat_As_Volatile (Etype (Pref)) then
6172 Force_Evaluation (Pref, Name_Req => True);
6174 elsif Nkind (Pref) = N_Selected_Component
6175 and then Is_Entity_Name (Prefix (Pref))
6180 Force_Evaluation (Pref, Name_Req => True);
6183 -- For a tagged type, use the scope of the original component to
6184 -- obtain the type, because ???
6186 if Is_Tagged_Type (Scope (Orig_Comp)) then
6187 Pref_Type := Scope (Orig_Comp);
6189 -- For an untagged derived type, use the discriminants of the parent
6190 -- which have been renamed in the derivation, possibly by a one-to-many
6191 -- discriminant constraint. For untagged type, initially get the Etype
6195 if Is_Derived_Type (Pref_Type)
6196 and then Number_Discriminants (Pref_Type) /=
6197 Number_Discriminants (Etype (Base_Type (Pref_Type)))
6199 Pref_Type := Etype (Base_Type (Pref_Type));
6203 -- We definitely should have a checking function, This routine should
6204 -- not be called if no discriminant checking function is present.
6206 pragma Assert (Present (Discr_Fct));
6208 -- Create the list of the actual parameters for the call. This list
6209 -- is the list of the discriminant fields of the record expression to
6210 -- be discriminant checked.
6213 Formal := First_Formal (Discr_Fct);
6214 Discr := First_Discriminant (Pref_Type);
6215 while Present (Discr) loop
6217 -- If we have a corresponding discriminant field, and a parent
6218 -- subtype is present, then we want to use the corresponding
6219 -- discriminant since this is the one with the useful value.
6221 if Present (Corresponding_Discriminant (Discr))
6222 and then Ekind (Pref_Type) = E_Record_Type
6223 and then Present (Parent_Subtype (Pref_Type))
6225 Real_Discr := Corresponding_Discriminant (Discr);
6227 Real_Discr := Discr;
6230 -- Construct the reference to the discriminant
6233 Make_Selected_Component (Loc,
6235 Unchecked_Convert_To (Pref_Type,
6236 Duplicate_Subexpr (Pref)),
6237 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
6239 -- Manually analyze and resolve this selected component. We really
6240 -- want it just as it appears above, and do not want the expander
6241 -- playing discriminal games etc with this reference. Then we append
6242 -- the argument to the list we are gathering.
6244 Set_Etype (Scomp, Etype (Real_Discr));
6245 Set_Analyzed (Scomp, True);
6246 Append_To (Args, Convert_To (Etype (Formal), Scomp));
6248 Next_Formal_With_Extras (Formal);
6249 Next_Discriminant (Discr);
6252 -- Now build and insert the call
6255 Make_Raise_Constraint_Error (Loc,
6257 Make_Function_Call (Loc,
6258 Name => New_Occurrence_Of (Discr_Fct, Loc),
6259 Parameter_Associations => Args),
6260 Reason => CE_Discriminant_Check_Failed));
6261 end Generate_Discriminant_Check;
6263 ---------------------------
6264 -- Generate_Index_Checks --
6265 ---------------------------
6267 procedure Generate_Index_Checks (N : Node_Id) is
6269 function Entity_Of_Prefix return Entity_Id;
6270 -- Returns the entity of the prefix of N (or Empty if not found)
6272 ----------------------
6273 -- Entity_Of_Prefix --
6274 ----------------------
6276 function Entity_Of_Prefix return Entity_Id is
6281 while not Is_Entity_Name (P) loop
6282 if not Nkind_In (P, N_Selected_Component,
6283 N_Indexed_Component)
6292 end Entity_Of_Prefix;
6296 Loc : constant Source_Ptr := Sloc (N);
6297 A : constant Node_Id := Prefix (N);
6298 A_Ent : constant Entity_Id := Entity_Of_Prefix;
6301 -- Start of processing for Generate_Index_Checks
6304 -- Ignore call if the prefix is not an array since we have a serious
6305 -- error in the sources. Ignore it also if index checks are suppressed
6306 -- for array object or type.
6308 if not Is_Array_Type (Etype (A))
6309 or else (Present (A_Ent) and then Index_Checks_Suppressed (A_Ent))
6310 or else Index_Checks_Suppressed (Etype (A))
6314 -- The indexed component we are dealing with contains 'Loop_Entry in its
6315 -- prefix. This case arises when analysis has determined that constructs
6318 -- Prefix'Loop_Entry (Expr)
6319 -- Prefix'Loop_Entry (Expr1, Expr2, ... ExprN)
6321 -- require rewriting for error detection purposes. A side effect of this
6322 -- action is the generation of index checks that mention 'Loop_Entry.
6323 -- Delay the generation of the check until 'Loop_Entry has been properly
6324 -- expanded. This is done in Expand_Loop_Entry_Attributes.
6326 elsif Nkind (Prefix (N)) = N_Attribute_Reference
6327 and then Attribute_Name (Prefix (N)) = Name_Loop_Entry
6332 -- Generate a raise of constraint error with the appropriate reason and
6333 -- a condition of the form:
6335 -- Base_Type (Sub) not in Array'Range (Subscript)
6337 -- Note that the reason we generate the conversion to the base type here
6338 -- is that we definitely want the range check to take place, even if it
6339 -- looks like the subtype is OK. Optimization considerations that allow
6340 -- us to omit the check have already been taken into account in the
6341 -- setting of the Do_Range_Check flag earlier on.
6343 Sub := First (Expressions (N));
6345 -- Handle string literals
6347 if Ekind (Etype (A)) = E_String_Literal_Subtype then
6348 if Do_Range_Check (Sub) then
6349 Set_Do_Range_Check (Sub, False);
6351 -- For string literals we obtain the bounds of the string from the
6352 -- associated subtype.
6355 Make_Raise_Constraint_Error (Loc,
6359 Convert_To (Base_Type (Etype (Sub)),
6360 Duplicate_Subexpr_Move_Checks (Sub)),
6362 Make_Attribute_Reference (Loc,
6363 Prefix => New_Occurrence_Of (Etype (A), Loc),
6364 Attribute_Name => Name_Range)),
6365 Reason => CE_Index_Check_Failed));
6372 A_Idx : Node_Id := Empty;
6379 A_Idx := First_Index (Etype (A));
6381 while Present (Sub) loop
6382 if Do_Range_Check (Sub) then
6383 Set_Do_Range_Check (Sub, False);
6385 -- Force evaluation except for the case of a simple name of
6386 -- a nonvolatile entity.
6388 if not Is_Entity_Name (Sub)
6389 or else Treat_As_Volatile (Entity (Sub))
6391 Force_Evaluation (Sub);
6394 if Nkind (A_Idx) = N_Range then
6397 elsif Nkind (A_Idx) = N_Identifier
6398 or else Nkind (A_Idx) = N_Expanded_Name
6400 A_Range := Scalar_Range (Entity (A_Idx));
6402 else pragma Assert (Nkind (A_Idx) = N_Subtype_Indication);
6403 A_Range := Range_Expression (Constraint (A_Idx));
6406 -- For array objects with constant bounds we can generate
6407 -- the index check using the bounds of the type of the index
6410 and then Ekind (A_Ent) = E_Variable
6411 and then Is_Constant_Bound (Low_Bound (A_Range))
6412 and then Is_Constant_Bound (High_Bound (A_Range))
6415 Make_Attribute_Reference (Loc,
6417 New_Occurrence_Of (Etype (A_Idx), Loc),
6418 Attribute_Name => Name_Range);
6420 -- For arrays with non-constant bounds we cannot generate
6421 -- the index check using the bounds of the type of the index
6422 -- since it may reference discriminants of some enclosing
6423 -- type. We obtain the bounds directly from the prefix
6430 Num := New_List (Make_Integer_Literal (Loc, Ind));
6434 Make_Attribute_Reference (Loc,
6436 Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
6437 Attribute_Name => Name_Range,
6438 Expressions => Num);
6442 Make_Raise_Constraint_Error (Loc,
6446 Convert_To (Base_Type (Etype (Sub)),
6447 Duplicate_Subexpr_Move_Checks (Sub)),
6448 Right_Opnd => Range_N),
6449 Reason => CE_Index_Check_Failed));
6452 A_Idx := Next_Index (A_Idx);
6458 end Generate_Index_Checks;
6460 --------------------------
6461 -- Generate_Range_Check --
6462 --------------------------
6464 procedure Generate_Range_Check
6466 Target_Type : Entity_Id;
6467 Reason : RT_Exception_Code)
6469 Loc : constant Source_Ptr := Sloc (N);
6470 Source_Type : constant Entity_Id := Etype (N);
6471 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
6472 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
6474 procedure Convert_And_Check_Range;
6475 -- Convert the conversion operand to the target base type and save in
6476 -- a temporary. Then check the converted value against the range of the
6479 -----------------------------
6480 -- Convert_And_Check_Range --
6481 -----------------------------
6483 procedure Convert_And_Check_Range is
6484 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
6487 -- We make a temporary to hold the value of the converted value
6488 -- (converted to the base type), and then do the test against this
6489 -- temporary. The conversion itself is replaced by an occurrence of
6490 -- Tnn and followed by the explicit range check. Note that checks
6491 -- are suppressed for this code, since we don't want a recursive
6492 -- range check popping up.
6494 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
6495 -- [constraint_error when Tnn not in Target_Type]
6497 Insert_Actions (N, New_List (
6498 Make_Object_Declaration (Loc,
6499 Defining_Identifier => Tnn,
6500 Object_Definition => New_Occurrence_Of (Target_Base_Type, Loc),
6501 Constant_Present => True,
6503 Make_Type_Conversion (Loc,
6504 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
6505 Expression => Duplicate_Subexpr (N))),
6507 Make_Raise_Constraint_Error (Loc,
6510 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
6511 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
6513 Suppress => All_Checks);
6515 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
6517 -- Set the type of N, because the declaration for Tnn might not
6518 -- be analyzed yet, as is the case if N appears within a record
6519 -- declaration, as a discriminant constraint or expression.
6521 Set_Etype (N, Target_Base_Type);
6522 end Convert_And_Check_Range;
6524 -- Start of processing for Generate_Range_Check
6527 -- First special case, if the source type is already within the range
6528 -- of the target type, then no check is needed (probably we should have
6529 -- stopped Do_Range_Check from being set in the first place, but better
6530 -- late than never in preventing junk code and junk flag settings.
6532 if In_Subrange_Of (Source_Type, Target_Type)
6534 -- We do NOT apply this if the source node is a literal, since in this
6535 -- case the literal has already been labeled as having the subtype of
6539 (Nkind_In (N, N_Integer_Literal, N_Real_Literal, N_Character_Literal)
6542 and then Ekind (Entity (N)) = E_Enumeration_Literal))
6544 Set_Do_Range_Check (N, False);
6548 -- Here a check is needed. If the expander is not active, or if we are
6549 -- in GNATProve mode, then simply set the Do_Range_Check flag and we
6550 -- are done. In both these cases, we just want to see the range check
6551 -- flag set, we do not want to generate the explicit range check code.
6553 if GNATprove_Mode or else not Expander_Active then
6554 Set_Do_Range_Check (N, True);
6558 -- Here we will generate an explicit range check, so we don't want to
6559 -- set the Do_Range check flag, since the range check is taken care of
6560 -- by the code we will generate.
6562 Set_Do_Range_Check (N, False);
6564 -- Force evaluation of the node, so that it does not get evaluated twice
6565 -- (once for the check, once for the actual reference). Such a double
6566 -- evaluation is always a potential source of inefficiency, and is
6567 -- functionally incorrect in the volatile case.
6569 if not Is_Entity_Name (N) or else Treat_As_Volatile (Entity (N)) then
6570 Force_Evaluation (N);
6573 -- The easiest case is when Source_Base_Type and Target_Base_Type are
6574 -- the same since in this case we can simply do a direct check of the
6575 -- value of N against the bounds of Target_Type.
6577 -- [constraint_error when N not in Target_Type]
6579 -- Note: this is by far the most common case, for example all cases of
6580 -- checks on the RHS of assignments are in this category, but not all
6581 -- cases are like this. Notably conversions can involve two types.
6583 if Source_Base_Type = Target_Base_Type then
6585 -- Insert the explicit range check. Note that we suppress checks for
6586 -- this code, since we don't want a recursive range check popping up.
6589 Make_Raise_Constraint_Error (Loc,
6592 Left_Opnd => Duplicate_Subexpr (N),
6593 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
6595 Suppress => All_Checks);
6597 -- Next test for the case where the target type is within the bounds
6598 -- of the base type of the source type, since in this case we can
6599 -- simply convert these bounds to the base type of T to do the test.
6601 -- [constraint_error when N not in
6602 -- Source_Base_Type (Target_Type'First)
6604 -- Source_Base_Type(Target_Type'Last))]
6606 -- The conversions will always work and need no check
6608 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
6609 -- of converting from an enumeration value to an integer type, such as
6610 -- occurs for the case of generating a range check on Enum'Val(Exp)
6611 -- (which used to be handled by gigi). This is OK, since the conversion
6612 -- itself does not require a check.
6614 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
6616 -- Insert the explicit range check. Note that we suppress checks for
6617 -- this code, since we don't want a recursive range check popping up.
6619 if Is_Discrete_Type (Source_Base_Type)
6621 Is_Discrete_Type (Target_Base_Type)
6624 Make_Raise_Constraint_Error (Loc,
6627 Left_Opnd => Duplicate_Subexpr (N),
6632 Unchecked_Convert_To (Source_Base_Type,
6633 Make_Attribute_Reference (Loc,
6635 New_Occurrence_Of (Target_Type, Loc),
6636 Attribute_Name => Name_First)),
6639 Unchecked_Convert_To (Source_Base_Type,
6640 Make_Attribute_Reference (Loc,
6642 New_Occurrence_Of (Target_Type, Loc),
6643 Attribute_Name => Name_Last)))),
6645 Suppress => All_Checks);
6647 -- For conversions involving at least one type that is not discrete,
6648 -- first convert to target type and then generate the range check.
6649 -- This avoids problems with values that are close to a bound of the
6650 -- target type that would fail a range check when done in a larger
6651 -- source type before converting but would pass if converted with
6652 -- rounding and then checked (such as in float-to-float conversions).
6655 Convert_And_Check_Range;
6658 -- Note that at this stage we now that the Target_Base_Type is not in
6659 -- the range of the Source_Base_Type (since even the Target_Type itself
6660 -- is not in this range). It could still be the case that Source_Type is
6661 -- in range of the target base type since we have not checked that case.
6663 -- If that is the case, we can freely convert the source to the target,
6664 -- and then test the target result against the bounds.
6666 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
6667 Convert_And_Check_Range;
6669 -- At this stage, we know that we have two scalar types, which are
6670 -- directly convertible, and where neither scalar type has a base
6671 -- range that is in the range of the other scalar type.
6673 -- The only way this can happen is with a signed and unsigned type.
6674 -- So test for these two cases:
6677 -- Case of the source is unsigned and the target is signed
6679 if Is_Unsigned_Type (Source_Base_Type)
6680 and then not Is_Unsigned_Type (Target_Base_Type)
6682 -- If the source is unsigned and the target is signed, then we
6683 -- know that the source is not shorter than the target (otherwise
6684 -- the source base type would be in the target base type range).
6686 -- In other words, the unsigned type is either the same size as
6687 -- the target, or it is larger. It cannot be smaller.
6690 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
6692 -- We only need to check the low bound if the low bound of the
6693 -- target type is non-negative. If the low bound of the target
6694 -- type is negative, then we know that we will fit fine.
6696 -- If the high bound of the target type is negative, then we
6697 -- know we have a constraint error, since we can't possibly
6698 -- have a negative source.
6700 -- With these two checks out of the way, we can do the check
6701 -- using the source type safely
6703 -- This is definitely the most annoying case.
6705 -- [constraint_error
6706 -- when (Target_Type'First >= 0
6708 -- N < Source_Base_Type (Target_Type'First))
6709 -- or else Target_Type'Last < 0
6710 -- or else N > Source_Base_Type (Target_Type'Last)];
6712 -- We turn off all checks since we know that the conversions
6713 -- will work fine, given the guards for negative values.
6716 Make_Raise_Constraint_Error (Loc,
6722 Left_Opnd => Make_Op_Ge (Loc,
6724 Make_Attribute_Reference (Loc,
6726 New_Occurrence_Of (Target_Type, Loc),
6727 Attribute_Name => Name_First),
6728 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
6732 Left_Opnd => Duplicate_Subexpr (N),
6734 Convert_To (Source_Base_Type,
6735 Make_Attribute_Reference (Loc,
6737 New_Occurrence_Of (Target_Type, Loc),
6738 Attribute_Name => Name_First)))),
6743 Make_Attribute_Reference (Loc,
6744 Prefix => New_Occurrence_Of (Target_Type, Loc),
6745 Attribute_Name => Name_Last),
6746 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
6750 Left_Opnd => Duplicate_Subexpr (N),
6752 Convert_To (Source_Base_Type,
6753 Make_Attribute_Reference (Loc,
6754 Prefix => New_Occurrence_Of (Target_Type, Loc),
6755 Attribute_Name => Name_Last)))),
6758 Suppress => All_Checks);
6760 -- Only remaining possibility is that the source is signed and
6761 -- the target is unsigned.
6764 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
6765 and then Is_Unsigned_Type (Target_Base_Type));
6767 -- If the source is signed and the target is unsigned, then we
6768 -- know that the target is not shorter than the source (otherwise
6769 -- the target base type would be in the source base type range).
6771 -- In other words, the unsigned type is either the same size as
6772 -- the target, or it is larger. It cannot be smaller.
6774 -- Clearly we have an error if the source value is negative since
6775 -- no unsigned type can have negative values. If the source type
6776 -- is non-negative, then the check can be done using the target
6779 -- Tnn : constant Target_Base_Type (N) := Target_Type;
6781 -- [constraint_error
6782 -- when N < 0 or else Tnn not in Target_Type];
6784 -- We turn off all checks for the conversion of N to the target
6785 -- base type, since we generate the explicit check to ensure that
6786 -- the value is non-negative
6789 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
6792 Insert_Actions (N, New_List (
6793 Make_Object_Declaration (Loc,
6794 Defining_Identifier => Tnn,
6795 Object_Definition =>
6796 New_Occurrence_Of (Target_Base_Type, Loc),
6797 Constant_Present => True,
6799 Make_Unchecked_Type_Conversion (Loc,
6801 New_Occurrence_Of (Target_Base_Type, Loc),
6802 Expression => Duplicate_Subexpr (N))),
6804 Make_Raise_Constraint_Error (Loc,
6809 Left_Opnd => Duplicate_Subexpr (N),
6810 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
6814 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
6816 New_Occurrence_Of (Target_Type, Loc))),
6819 Suppress => All_Checks);
6821 -- Set the Etype explicitly, because Insert_Actions may have
6822 -- placed the declaration in the freeze list for an enclosing
6823 -- construct, and thus it is not analyzed yet.
6825 Set_Etype (Tnn, Target_Base_Type);
6826 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
6830 end Generate_Range_Check;
6836 function Get_Check_Id (N : Name_Id) return Check_Id is
6838 -- For standard check name, we can do a direct computation
6840 if N in First_Check_Name .. Last_Check_Name then
6841 return Check_Id (N - (First_Check_Name - 1));
6843 -- For non-standard names added by pragma Check_Name, search table
6846 for J in All_Checks + 1 .. Check_Names.Last loop
6847 if Check_Names.Table (J) = N then
6853 -- No matching name found
6858 ---------------------
6859 -- Get_Discriminal --
6860 ---------------------
6862 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
6863 Loc : constant Source_Ptr := Sloc (E);
6868 -- The bound can be a bona fide parameter of a protected operation,
6869 -- rather than a prival encoded as an in-parameter.
6871 if No (Discriminal_Link (Entity (Bound))) then
6875 -- Climb the scope stack looking for an enclosing protected type. If
6876 -- we run out of scopes, return the bound itself.
6879 while Present (Sc) loop
6880 if Sc = Standard_Standard then
6882 elsif Ekind (Sc) = E_Protected_Type then
6889 D := First_Discriminant (Sc);
6890 while Present (D) loop
6891 if Chars (D) = Chars (Bound) then
6892 return New_Occurrence_Of (Discriminal (D), Loc);
6895 Next_Discriminant (D);
6899 end Get_Discriminal;
6901 ----------------------
6902 -- Get_Range_Checks --
6903 ----------------------
6905 function Get_Range_Checks
6907 Target_Typ : Entity_Id;
6908 Source_Typ : Entity_Id := Empty;
6909 Warn_Node : Node_Id := Empty) return Check_Result
6913 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
6914 end Get_Range_Checks;
6920 function Guard_Access
6923 Ck_Node : Node_Id) return Node_Id
6926 if Nkind (Cond) = N_Or_Else then
6927 Set_Paren_Count (Cond, 1);
6930 if Nkind (Ck_Node) = N_Allocator then
6938 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
6939 Right_Opnd => Make_Null (Loc)),
6940 Right_Opnd => Cond);
6944 -----------------------------
6945 -- Index_Checks_Suppressed --
6946 -----------------------------
6948 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
6950 if Present (E) and then Checks_May_Be_Suppressed (E) then
6951 return Is_Check_Suppressed (E, Index_Check);
6953 return Scope_Suppress.Suppress (Index_Check);
6955 end Index_Checks_Suppressed;
6961 procedure Initialize is
6963 for J in Determine_Range_Cache_N'Range loop
6964 Determine_Range_Cache_N (J) := Empty;
6969 for J in Int range 1 .. All_Checks loop
6970 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
6974 -------------------------
6975 -- Insert_Range_Checks --
6976 -------------------------
6978 procedure Insert_Range_Checks
6979 (Checks : Check_Result;
6981 Suppress_Typ : Entity_Id;
6982 Static_Sloc : Source_Ptr := No_Location;
6983 Flag_Node : Node_Id := Empty;
6984 Do_Before : Boolean := False)
6986 Internal_Flag_Node : Node_Id := Flag_Node;
6987 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
6989 Check_Node : Node_Id;
6990 Checks_On : constant Boolean :=
6991 (not Index_Checks_Suppressed (Suppress_Typ))
6992 or else (not Range_Checks_Suppressed (Suppress_Typ));
6995 -- For now we just return if Checks_On is false, however this should be
6996 -- enhanced to check for an always True value in the condition and to
6997 -- generate a compilation warning???
6999 if not Expander_Active or not Checks_On then
7003 if Static_Sloc = No_Location then
7004 Internal_Static_Sloc := Sloc (Node);
7007 if No (Flag_Node) then
7008 Internal_Flag_Node := Node;
7011 for J in 1 .. 2 loop
7012 exit when No (Checks (J));
7014 if Nkind (Checks (J)) = N_Raise_Constraint_Error
7015 and then Present (Condition (Checks (J)))
7017 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
7018 Check_Node := Checks (J);
7019 Mark_Rewrite_Insertion (Check_Node);
7022 Insert_Before_And_Analyze (Node, Check_Node);
7024 Insert_After_And_Analyze (Node, Check_Node);
7027 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
7032 Make_Raise_Constraint_Error (Internal_Static_Sloc,
7033 Reason => CE_Range_Check_Failed);
7034 Mark_Rewrite_Insertion (Check_Node);
7037 Insert_Before_And_Analyze (Node, Check_Node);
7039 Insert_After_And_Analyze (Node, Check_Node);
7043 end Insert_Range_Checks;
7045 ------------------------
7046 -- Insert_Valid_Check --
7047 ------------------------
7049 procedure Insert_Valid_Check
7051 Related_Id : Entity_Id := Empty;
7052 Is_Low_Bound : Boolean := False;
7053 Is_High_Bound : Boolean := False)
7055 Loc : constant Source_Ptr := Sloc (Expr);
7056 Typ : constant Entity_Id := Etype (Expr);
7060 -- Do not insert if checks off, or if not checking validity or if
7061 -- expression is known to be valid.
7063 if not Validity_Checks_On
7064 or else Range_Or_Validity_Checks_Suppressed (Expr)
7065 or else Expr_Known_Valid (Expr)
7070 -- Do not insert checks within a predicate function. This will arise
7071 -- if the current unit and the predicate function are being compiled
7072 -- with validity checks enabled.
7074 if Present (Predicate_Function (Typ))
7075 and then Current_Scope = Predicate_Function (Typ)
7080 -- If the expression is a packed component of a modular type of the
7081 -- right size, the data is always valid.
7083 if Nkind (Expr) = N_Selected_Component
7084 and then Present (Component_Clause (Entity (Selector_Name (Expr))))
7085 and then Is_Modular_Integer_Type (Typ)
7086 and then Modulus (Typ) = 2 ** Esize (Entity (Selector_Name (Expr)))
7091 -- If we have a checked conversion, then validity check applies to
7092 -- the expression inside the conversion, not the result, since if
7093 -- the expression inside is valid, then so is the conversion result.
7096 while Nkind (Exp) = N_Type_Conversion loop
7097 Exp := Expression (Exp);
7100 -- We are about to insert the validity check for Exp. We save and
7101 -- reset the Do_Range_Check flag over this validity check, and then
7102 -- put it back for the final original reference (Exp may be rewritten).
7105 DRC : constant Boolean := Do_Range_Check (Exp);
7110 Set_Do_Range_Check (Exp, False);
7112 -- Force evaluation to avoid multiple reads for atomic/volatile
7114 -- Note: we set Name_Req to False. We used to set it to True, with
7115 -- the thinking that a name is required as the prefix of the 'Valid
7116 -- call, but in fact the check that the prefix of an attribute is
7117 -- a name is in the parser, and we just don't require it here.
7118 -- Moreover, when we set Name_Req to True, that interfered with the
7119 -- checking for Volatile, since we couldn't just capture the value.
7121 if Is_Entity_Name (Exp)
7122 and then Is_Volatile (Entity (Exp))
7124 -- Same reasoning as above for setting Name_Req to False
7126 Force_Evaluation (Exp, Name_Req => False);
7129 -- Build the prefix for the 'Valid call
7132 Duplicate_Subexpr_No_Checks
7135 Related_Id => Related_Id,
7136 Is_Low_Bound => Is_Low_Bound,
7137 Is_High_Bound => Is_High_Bound);
7139 -- A rather specialized test. If PV is an analyzed expression which
7140 -- is an indexed component of a packed array that has not been
7141 -- properly expanded, turn off its Analyzed flag to make sure it
7142 -- gets properly reexpanded. If the prefix is an access value,
7143 -- the dereference will be added later.
7145 -- The reason this arises is that Duplicate_Subexpr_No_Checks did
7146 -- an analyze with the old parent pointer. This may point e.g. to
7147 -- a subprogram call, which deactivates this expansion.
7150 and then Nkind (PV) = N_Indexed_Component
7151 and then Is_Array_Type (Etype (Prefix (PV)))
7152 and then Present (Packed_Array_Impl_Type (Etype (Prefix (PV))))
7154 Set_Analyzed (PV, False);
7157 -- Build the raise CE node to check for validity. We build a type
7158 -- qualification for the prefix, since it may not be of the form of
7159 -- a name, and we don't care in this context!
7162 Make_Raise_Constraint_Error (Loc,
7166 Make_Attribute_Reference (Loc,
7168 Attribute_Name => Name_Valid)),
7169 Reason => CE_Invalid_Data);
7171 -- Insert the validity check. Note that we do this with validity
7172 -- checks turned off, to avoid recursion, we do not want validity
7173 -- checks on the validity checking code itself.
7175 Insert_Action (Expr, CE, Suppress => Validity_Check);
7177 -- If the expression is a reference to an element of a bit-packed
7178 -- array, then it is rewritten as a renaming declaration. If the
7179 -- expression is an actual in a call, it has not been expanded,
7180 -- waiting for the proper point at which to do it. The same happens
7181 -- with renamings, so that we have to force the expansion now. This
7182 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
7185 if Is_Entity_Name (Exp)
7186 and then Nkind (Parent (Entity (Exp))) =
7187 N_Object_Renaming_Declaration
7190 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
7192 if Nkind (Old_Exp) = N_Indexed_Component
7193 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
7195 Expand_Packed_Element_Reference (Old_Exp);
7200 -- Put back the Do_Range_Check flag on the resulting (possibly
7201 -- rewritten) expression.
7203 -- Note: it might be thought that a validity check is not required
7204 -- when a range check is present, but that's not the case, because
7205 -- the back end is allowed to assume for the range check that the
7206 -- operand is within its declared range (an assumption that validity
7207 -- checking is all about NOT assuming).
7209 -- Note: no need to worry about Possible_Local_Raise here, it will
7210 -- already have been called if original node has Do_Range_Check set.
7212 Set_Do_Range_Check (Exp, DRC);
7214 end Insert_Valid_Check;
7216 -------------------------------------
7217 -- Is_Signed_Integer_Arithmetic_Op --
7218 -------------------------------------
7220 function Is_Signed_Integer_Arithmetic_Op (N : Node_Id) return Boolean is
7223 when N_Op_Abs | N_Op_Add | N_Op_Divide | N_Op_Expon |
7224 N_Op_Minus | N_Op_Mod | N_Op_Multiply | N_Op_Plus |
7225 N_Op_Rem | N_Op_Subtract =>
7226 return Is_Signed_Integer_Type (Etype (N));
7228 when N_If_Expression | N_Case_Expression =>
7229 return Is_Signed_Integer_Type (Etype (N));
7234 end Is_Signed_Integer_Arithmetic_Op;
7236 ----------------------------------
7237 -- Install_Null_Excluding_Check --
7238 ----------------------------------
7240 procedure Install_Null_Excluding_Check (N : Node_Id) is
7241 Loc : constant Source_Ptr := Sloc (Parent (N));
7242 Typ : constant Entity_Id := Etype (N);
7244 function Safe_To_Capture_In_Parameter_Value return Boolean;
7245 -- Determines if it is safe to capture Known_Non_Null status for an
7246 -- the entity referenced by node N. The caller ensures that N is indeed
7247 -- an entity name. It is safe to capture the non-null status for an IN
7248 -- parameter when the reference occurs within a declaration that is sure
7249 -- to be executed as part of the declarative region.
7251 procedure Mark_Non_Null;
7252 -- After installation of check, if the node in question is an entity
7253 -- name, then mark this entity as non-null if possible.
7255 function Safe_To_Capture_In_Parameter_Value return Boolean is
7256 E : constant Entity_Id := Entity (N);
7257 S : constant Entity_Id := Current_Scope;
7261 if Ekind (E) /= E_In_Parameter then
7265 -- Two initial context checks. We must be inside a subprogram body
7266 -- with declarations and reference must not appear in nested scopes.
7268 if (Ekind (S) /= E_Function and then Ekind (S) /= E_Procedure)
7269 or else Scope (E) /= S
7274 S_Par := Parent (Parent (S));
7276 if Nkind (S_Par) /= N_Subprogram_Body
7277 or else No (Declarations (S_Par))
7287 -- Retrieve the declaration node of N (if any). Note that N
7288 -- may be a part of a complex initialization expression.
7292 while Present (P) loop
7294 -- If we have a short circuit form, and we are within the right
7295 -- hand expression, we return false, since the right hand side
7296 -- is not guaranteed to be elaborated.
7298 if Nkind (P) in N_Short_Circuit
7299 and then N = Right_Opnd (P)
7304 -- Similarly, if we are in an if expression and not part of the
7305 -- condition, then we return False, since neither the THEN or
7306 -- ELSE dependent expressions will always be elaborated.
7308 if Nkind (P) = N_If_Expression
7309 and then N /= First (Expressions (P))
7314 -- If within a case expression, and not part of the expression,
7315 -- then return False, since a particular dependent expression
7316 -- may not always be elaborated
7318 if Nkind (P) = N_Case_Expression
7319 and then N /= Expression (P)
7324 -- While traversing the parent chain, if node N belongs to a
7325 -- statement, then it may never appear in a declarative region.
7327 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
7328 or else Nkind (P) = N_Procedure_Call_Statement
7333 -- If we are at a declaration, record it and exit
7335 if Nkind (P) in N_Declaration
7336 and then Nkind (P) not in N_Subprogram_Specification
7349 return List_Containing (N_Decl) = Declarations (S_Par);
7351 end Safe_To_Capture_In_Parameter_Value;
7357 procedure Mark_Non_Null is
7359 -- Only case of interest is if node N is an entity name
7361 if Is_Entity_Name (N) then
7363 -- For sure, we want to clear an indication that this is known to
7364 -- be null, since if we get past this check, it definitely is not.
7366 Set_Is_Known_Null (Entity (N), False);
7368 -- We can mark the entity as known to be non-null if either it is
7369 -- safe to capture the value, or in the case of an IN parameter,
7370 -- which is a constant, if the check we just installed is in the
7371 -- declarative region of the subprogram body. In this latter case,
7372 -- a check is decisive for the rest of the body if the expression
7373 -- is sure to be elaborated, since we know we have to elaborate
7374 -- all declarations before executing the body.
7376 -- Couldn't this always be part of Safe_To_Capture_Value ???
7378 if Safe_To_Capture_Value (N, Entity (N))
7379 or else Safe_To_Capture_In_Parameter_Value
7381 Set_Is_Known_Non_Null (Entity (N));
7386 -- Start of processing for Install_Null_Excluding_Check
7389 pragma Assert (Is_Access_Type (Typ));
7391 -- No check inside a generic, check will be emitted in instance
7393 if Inside_A_Generic then
7397 -- No check needed if known to be non-null
7399 if Known_Non_Null (N) then
7403 -- If known to be null, here is where we generate a compile time check
7405 if Known_Null (N) then
7407 -- Avoid generating warning message inside init procs. In SPARK mode
7408 -- we can go ahead and call Apply_Compile_Time_Constraint_Error
7409 -- since it will be turned into an error in any case.
7411 if (not Inside_Init_Proc or else SPARK_Mode = On)
7413 -- Do not emit the warning within a conditional expression,
7414 -- where the expression might not be evaluated, and the warning
7415 -- appear as extraneous noise.
7417 and then not Within_Case_Or_If_Expression (N)
7419 Apply_Compile_Time_Constraint_Error
7420 (N, "null value not allowed here??", CE_Access_Check_Failed);
7422 -- Remaining cases, where we silently insert the raise
7426 Make_Raise_Constraint_Error (Loc,
7427 Reason => CE_Access_Check_Failed));
7434 -- If entity is never assigned, for sure a warning is appropriate
7436 if Is_Entity_Name (N) then
7437 Check_Unset_Reference (N);
7440 -- No check needed if checks are suppressed on the range. Note that we
7441 -- don't set Is_Known_Non_Null in this case (we could legitimately do
7442 -- so, since the program is erroneous, but we don't like to casually
7443 -- propagate such conclusions from erroneosity).
7445 if Access_Checks_Suppressed (Typ) then
7449 -- No check needed for access to concurrent record types generated by
7450 -- the expander. This is not just an optimization (though it does indeed
7451 -- remove junk checks). It also avoids generation of junk warnings.
7453 if Nkind (N) in N_Has_Chars
7454 and then Chars (N) = Name_uObject
7455 and then Is_Concurrent_Record_Type
7456 (Directly_Designated_Type (Etype (N)))
7461 -- No check needed in interface thunks since the runtime check is
7462 -- already performed at the caller side.
7464 if Is_Thunk (Current_Scope) then
7468 -- No check needed for the Get_Current_Excep.all.all idiom generated by
7469 -- the expander within exception handlers, since we know that the value
7470 -- can never be null.
7472 -- Is this really the right way to do this? Normally we generate such
7473 -- code in the expander with checks off, and that's how we suppress this
7474 -- kind of junk check ???
7476 if Nkind (N) = N_Function_Call
7477 and then Nkind (Name (N)) = N_Explicit_Dereference
7478 and then Nkind (Prefix (Name (N))) = N_Identifier
7479 and then Is_RTE (Entity (Prefix (Name (N))), RE_Get_Current_Excep)
7484 -- Otherwise install access check
7487 Make_Raise_Constraint_Error (Loc,
7490 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
7491 Right_Opnd => Make_Null (Loc)),
7492 Reason => CE_Access_Check_Failed));
7495 end Install_Null_Excluding_Check;
7497 --------------------------
7498 -- Install_Static_Check --
7499 --------------------------
7501 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
7502 Stat : constant Boolean := Is_OK_Static_Expression (R_Cno);
7503 Typ : constant Entity_Id := Etype (R_Cno);
7507 Make_Raise_Constraint_Error (Loc,
7508 Reason => CE_Range_Check_Failed));
7509 Set_Analyzed (R_Cno);
7510 Set_Etype (R_Cno, Typ);
7511 Set_Raises_Constraint_Error (R_Cno);
7512 Set_Is_Static_Expression (R_Cno, Stat);
7514 -- Now deal with possible local raise handling
7516 Possible_Local_Raise (R_Cno, Standard_Constraint_Error);
7517 end Install_Static_Check;
7519 -------------------------
7520 -- Is_Check_Suppressed --
7521 -------------------------
7523 function Is_Check_Suppressed (E : Entity_Id; C : Check_Id) return Boolean is
7524 Ptr : Suppress_Stack_Entry_Ptr;
7527 -- First search the local entity suppress stack. We search this from the
7528 -- top of the stack down so that we get the innermost entry that applies
7529 -- to this case if there are nested entries.
7531 Ptr := Local_Suppress_Stack_Top;
7532 while Ptr /= null loop
7533 if (Ptr.Entity = Empty or else Ptr.Entity = E)
7534 and then (Ptr.Check = All_Checks or else Ptr.Check = C)
7536 return Ptr.Suppress;
7542 -- Now search the global entity suppress table for a matching entry.
7543 -- We also search this from the top down so that if there are multiple
7544 -- pragmas for the same entity, the last one applies (not clear what
7545 -- or whether the RM specifies this handling, but it seems reasonable).
7547 Ptr := Global_Suppress_Stack_Top;
7548 while Ptr /= null loop
7549 if (Ptr.Entity = Empty or else Ptr.Entity = E)
7550 and then (Ptr.Check = All_Checks or else Ptr.Check = C)
7552 return Ptr.Suppress;
7558 -- If we did not find a matching entry, then use the normal scope
7559 -- suppress value after all (actually this will be the global setting
7560 -- since it clearly was not overridden at any point). For a predefined
7561 -- check, we test the specific flag. For a user defined check, we check
7562 -- the All_Checks flag. The Overflow flag requires special handling to
7563 -- deal with the General vs Assertion case
7565 if C = Overflow_Check then
7566 return Overflow_Checks_Suppressed (Empty);
7567 elsif C in Predefined_Check_Id then
7568 return Scope_Suppress.Suppress (C);
7570 return Scope_Suppress.Suppress (All_Checks);
7572 end Is_Check_Suppressed;
7574 ---------------------
7575 -- Kill_All_Checks --
7576 ---------------------
7578 procedure Kill_All_Checks is
7580 if Debug_Flag_CC then
7581 w ("Kill_All_Checks");
7584 -- We reset the number of saved checks to zero, and also modify all
7585 -- stack entries for statement ranges to indicate that the number of
7586 -- checks at each level is now zero.
7588 Num_Saved_Checks := 0;
7590 -- Note: the Int'Min here avoids any possibility of J being out of
7591 -- range when called from e.g. Conditional_Statements_Begin.
7593 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
7594 Saved_Checks_Stack (J) := 0;
7596 end Kill_All_Checks;
7602 procedure Kill_Checks (V : Entity_Id) is
7604 if Debug_Flag_CC then
7605 w ("Kill_Checks for entity", Int (V));
7608 for J in 1 .. Num_Saved_Checks loop
7609 if Saved_Checks (J).Entity = V then
7610 if Debug_Flag_CC then
7611 w (" Checks killed for saved check ", J);
7614 Saved_Checks (J).Killed := True;
7619 ------------------------------
7620 -- Length_Checks_Suppressed --
7621 ------------------------------
7623 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
7625 if Present (E) and then Checks_May_Be_Suppressed (E) then
7626 return Is_Check_Suppressed (E, Length_Check);
7628 return Scope_Suppress.Suppress (Length_Check);
7630 end Length_Checks_Suppressed;
7632 -----------------------
7633 -- Make_Bignum_Block --
7634 -----------------------
7636 function Make_Bignum_Block (Loc : Source_Ptr) return Node_Id is
7637 M : constant Entity_Id := Make_Defining_Identifier (Loc, Name_uM);
7640 Make_Block_Statement (Loc,
7642 New_List (Build_SS_Mark_Call (Loc, M)),
7643 Handled_Statement_Sequence =>
7644 Make_Handled_Sequence_Of_Statements (Loc,
7645 Statements => New_List (Build_SS_Release_Call (Loc, M))));
7646 end Make_Bignum_Block;
7648 ----------------------------------
7649 -- Minimize_Eliminate_Overflows --
7650 ----------------------------------
7652 -- This is a recursive routine that is called at the top of an expression
7653 -- tree to properly process overflow checking for a whole subtree by making
7654 -- recursive calls to process operands. This processing may involve the use
7655 -- of bignum or long long integer arithmetic, which will change the types
7656 -- of operands and results. That's why we can't do this bottom up (since
7657 -- it would interfere with semantic analysis).
7659 -- What happens is that if MINIMIZED/ELIMINATED mode is in effect then
7660 -- the operator expansion routines, as well as the expansion routines for
7661 -- if/case expression, do nothing (for the moment) except call the routine
7662 -- to apply the overflow check (Apply_Arithmetic_Overflow_Check). That
7663 -- routine does nothing for non top-level nodes, so at the point where the
7664 -- call is made for the top level node, the entire expression subtree has
7665 -- not been expanded, or processed for overflow. All that has to happen as
7666 -- a result of the top level call to this routine.
7668 -- As noted above, the overflow processing works by making recursive calls
7669 -- for the operands, and figuring out what to do, based on the processing
7670 -- of these operands (e.g. if a bignum operand appears, the parent op has
7671 -- to be done in bignum mode), and the determined ranges of the operands.
7673 -- After possible rewriting of a constituent subexpression node, a call is
7674 -- made to either reexpand the node (if nothing has changed) or reanalyze
7675 -- the node (if it has been modified by the overflow check processing). The
7676 -- Analyzed_Flag is set to False before the reexpand/reanalyze. To avoid
7677 -- a recursive call into the whole overflow apparatus, an important rule
7678 -- for this call is that the overflow handling mode must be temporarily set
7681 procedure Minimize_Eliminate_Overflows
7685 Top_Level : Boolean)
7687 Rtyp : constant Entity_Id := Etype (N);
7688 pragma Assert (Is_Signed_Integer_Type (Rtyp));
7689 -- Result type, must be a signed integer type
7691 Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
7692 pragma Assert (Check_Mode in Minimized_Or_Eliminated);
7694 Loc : constant Source_Ptr := Sloc (N);
7697 -- Ranges of values for right operand (operator case)
7700 -- Ranges of values for left operand (operator case)
7702 LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer);
7703 -- Operands and results are of this type when we convert
7705 LLLo : constant Uint := Intval (Type_Low_Bound (LLIB));
7706 LLHi : constant Uint := Intval (Type_High_Bound (LLIB));
7707 -- Bounds of Long_Long_Integer
7709 Binary : constant Boolean := Nkind (N) in N_Binary_Op;
7710 -- Indicates binary operator case
7713 -- Used in call to Determine_Range
7715 Bignum_Operands : Boolean;
7716 -- Set True if one or more operands is already of type Bignum, meaning
7717 -- that for sure (regardless of Top_Level setting) we are committed to
7718 -- doing the operation in Bignum mode (or in the case of a case or if
7719 -- expression, converting all the dependent expressions to Bignum).
7721 Long_Long_Integer_Operands : Boolean;
7722 -- Set True if one or more operands is already of type Long_Long_Integer
7723 -- which means that if the result is known to be in the result type
7724 -- range, then we must convert such operands back to the result type.
7726 procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False);
7727 -- This is called when we have modified the node and we therefore need
7728 -- to reanalyze it. It is important that we reset the mode to STRICT for
7729 -- this reanalysis, since if we leave it in MINIMIZED or ELIMINATED mode
7730 -- we would reenter this routine recursively which would not be good.
7731 -- The argument Suppress is set True if we also want to suppress
7732 -- overflow checking for the reexpansion (this is set when we know
7733 -- overflow is not possible). Typ is the type for the reanalysis.
7735 procedure Reexpand (Suppress : Boolean := False);
7736 -- This is like Reanalyze, but does not do the Analyze step, it only
7737 -- does a reexpansion. We do this reexpansion in STRICT mode, so that
7738 -- instead of reentering the MINIMIZED/ELIMINATED mode processing, we
7739 -- follow the normal expansion path (e.g. converting A**4 to A**2**2).
7740 -- Note that skipping reanalysis is not just an optimization, testing
7741 -- has showed up several complex cases in which reanalyzing an already
7742 -- analyzed node causes incorrect behavior.
7744 function In_Result_Range return Boolean;
7745 -- Returns True iff Lo .. Hi are within range of the result type
7747 procedure Max (A : in out Uint; B : Uint);
7748 -- If A is No_Uint, sets A to B, else to UI_Max (A, B)
7750 procedure Min (A : in out Uint; B : Uint);
7751 -- If A is No_Uint, sets A to B, else to UI_Min (A, B)
7753 ---------------------
7754 -- In_Result_Range --
7755 ---------------------
7757 function In_Result_Range return Boolean is
7759 if Lo = No_Uint or else Hi = No_Uint then
7762 elsif Is_OK_Static_Subtype (Etype (N)) then
7763 return Lo >= Expr_Value (Type_Low_Bound (Rtyp))
7765 Hi <= Expr_Value (Type_High_Bound (Rtyp));
7768 return Lo >= Expr_Value (Type_Low_Bound (Base_Type (Rtyp)))
7770 Hi <= Expr_Value (Type_High_Bound (Base_Type (Rtyp)));
7772 end In_Result_Range;
7778 procedure Max (A : in out Uint; B : Uint) is
7780 if A = No_Uint or else B > A then
7789 procedure Min (A : in out Uint; B : Uint) is
7791 if A = No_Uint or else B < A then
7800 procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False) is
7801 Svg : constant Overflow_Mode_Type :=
7802 Scope_Suppress.Overflow_Mode_General;
7803 Sva : constant Overflow_Mode_Type :=
7804 Scope_Suppress.Overflow_Mode_Assertions;
7805 Svo : constant Boolean :=
7806 Scope_Suppress.Suppress (Overflow_Check);
7809 Scope_Suppress.Overflow_Mode_General := Strict;
7810 Scope_Suppress.Overflow_Mode_Assertions := Strict;
7813 Scope_Suppress.Suppress (Overflow_Check) := True;
7816 Analyze_And_Resolve (N, Typ);
7818 Scope_Suppress.Suppress (Overflow_Check) := Svo;
7819 Scope_Suppress.Overflow_Mode_General := Svg;
7820 Scope_Suppress.Overflow_Mode_Assertions := Sva;
7827 procedure Reexpand (Suppress : Boolean := False) is
7828 Svg : constant Overflow_Mode_Type :=
7829 Scope_Suppress.Overflow_Mode_General;
7830 Sva : constant Overflow_Mode_Type :=
7831 Scope_Suppress.Overflow_Mode_Assertions;
7832 Svo : constant Boolean :=
7833 Scope_Suppress.Suppress (Overflow_Check);
7836 Scope_Suppress.Overflow_Mode_General := Strict;
7837 Scope_Suppress.Overflow_Mode_Assertions := Strict;
7838 Set_Analyzed (N, False);
7841 Scope_Suppress.Suppress (Overflow_Check) := True;
7846 Scope_Suppress.Suppress (Overflow_Check) := Svo;
7847 Scope_Suppress.Overflow_Mode_General := Svg;
7848 Scope_Suppress.Overflow_Mode_Assertions := Sva;
7851 -- Start of processing for Minimize_Eliminate_Overflows
7854 -- Case where we do not have a signed integer arithmetic operation
7856 if not Is_Signed_Integer_Arithmetic_Op (N) then
7858 -- Use the normal Determine_Range routine to get the range. We
7859 -- don't require operands to be valid, invalid values may result in
7860 -- rubbish results where the result has not been properly checked for
7861 -- overflow, that's fine.
7863 Determine_Range (N, OK, Lo, Hi, Assume_Valid => False);
7865 -- If Determine_Range did not work (can this in fact happen? Not
7866 -- clear but might as well protect), use type bounds.
7869 Lo := Intval (Type_Low_Bound (Base_Type (Etype (N))));
7870 Hi := Intval (Type_High_Bound (Base_Type (Etype (N))));
7873 -- If we don't have a binary operator, all we have to do is to set
7874 -- the Hi/Lo range, so we are done.
7878 -- Processing for if expression
7880 elsif Nkind (N) = N_If_Expression then
7882 Then_DE : constant Node_Id := Next (First (Expressions (N)));
7883 Else_DE : constant Node_Id := Next (Then_DE);
7886 Bignum_Operands := False;
7888 Minimize_Eliminate_Overflows
7889 (Then_DE, Lo, Hi, Top_Level => False);
7891 if Lo = No_Uint then
7892 Bignum_Operands := True;
7895 Minimize_Eliminate_Overflows
7896 (Else_DE, Rlo, Rhi, Top_Level => False);
7898 if Rlo = No_Uint then
7899 Bignum_Operands := True;
7901 Long_Long_Integer_Operands :=
7902 Etype (Then_DE) = LLIB or else Etype (Else_DE) = LLIB;
7908 -- If at least one of our operands is now Bignum, we must rebuild
7909 -- the if expression to use Bignum operands. We will analyze the
7910 -- rebuilt if expression with overflow checks off, since once we
7911 -- are in bignum mode, we are all done with overflow checks.
7913 if Bignum_Operands then
7915 Make_If_Expression (Loc,
7916 Expressions => New_List (
7917 Remove_Head (Expressions (N)),
7918 Convert_To_Bignum (Then_DE),
7919 Convert_To_Bignum (Else_DE)),
7920 Is_Elsif => Is_Elsif (N)));
7922 Reanalyze (RTE (RE_Bignum), Suppress => True);
7924 -- If we have no Long_Long_Integer operands, then we are in result
7925 -- range, since it means that none of our operands felt the need
7926 -- to worry about overflow (otherwise it would have already been
7927 -- converted to long long integer or bignum). We reexpand to
7928 -- complete the expansion of the if expression (but we do not
7929 -- need to reanalyze).
7931 elsif not Long_Long_Integer_Operands then
7932 Set_Do_Overflow_Check (N, False);
7935 -- Otherwise convert us to long long integer mode. Note that we
7936 -- don't need any further overflow checking at this level.
7939 Convert_To_And_Rewrite (LLIB, Then_DE);
7940 Convert_To_And_Rewrite (LLIB, Else_DE);
7941 Set_Etype (N, LLIB);
7943 -- Now reanalyze with overflow checks off
7945 Set_Do_Overflow_Check (N, False);
7946 Reanalyze (LLIB, Suppress => True);
7952 -- Here for case expression
7954 elsif Nkind (N) = N_Case_Expression then
7955 Bignum_Operands := False;
7956 Long_Long_Integer_Operands := False;
7962 -- Loop through expressions applying recursive call
7964 Alt := First (Alternatives (N));
7965 while Present (Alt) loop
7967 Aexp : constant Node_Id := Expression (Alt);
7970 Minimize_Eliminate_Overflows
7971 (Aexp, Lo, Hi, Top_Level => False);
7973 if Lo = No_Uint then
7974 Bignum_Operands := True;
7975 elsif Etype (Aexp) = LLIB then
7976 Long_Long_Integer_Operands := True;
7983 -- If we have no bignum or long long integer operands, it means
7984 -- that none of our dependent expressions could raise overflow.
7985 -- In this case, we simply return with no changes except for
7986 -- resetting the overflow flag, since we are done with overflow
7987 -- checks for this node. We will reexpand to get the needed
7988 -- expansion for the case expression, but we do not need to
7989 -- reanalyze, since nothing has changed.
7991 if not (Bignum_Operands or Long_Long_Integer_Operands) then
7992 Set_Do_Overflow_Check (N, False);
7993 Reexpand (Suppress => True);
7995 -- Otherwise we are going to rebuild the case expression using
7996 -- either bignum or long long integer operands throughout.
8005 New_Alts := New_List;
8006 Alt := First (Alternatives (N));
8007 while Present (Alt) loop
8008 if Bignum_Operands then
8009 New_Exp := Convert_To_Bignum (Expression (Alt));
8010 Rtype := RTE (RE_Bignum);
8012 New_Exp := Convert_To (LLIB, Expression (Alt));
8016 Append_To (New_Alts,
8017 Make_Case_Expression_Alternative (Sloc (Alt),
8019 Discrete_Choices => Discrete_Choices (Alt),
8020 Expression => New_Exp));
8026 Make_Case_Expression (Loc,
8027 Expression => Expression (N),
8028 Alternatives => New_Alts));
8030 Reanalyze (Rtype, Suppress => True);
8038 -- If we have an arithmetic operator we make recursive calls on the
8039 -- operands to get the ranges (and to properly process the subtree
8040 -- that lies below us).
8042 Minimize_Eliminate_Overflows
8043 (Right_Opnd (N), Rlo, Rhi, Top_Level => False);
8046 Minimize_Eliminate_Overflows
8047 (Left_Opnd (N), Llo, Lhi, Top_Level => False);
8050 -- Record if we have Long_Long_Integer operands
8052 Long_Long_Integer_Operands :=
8053 Etype (Right_Opnd (N)) = LLIB
8054 or else (Binary and then Etype (Left_Opnd (N)) = LLIB);
8056 -- If either operand is a bignum, then result will be a bignum and we
8057 -- don't need to do any range analysis. As previously discussed we could
8058 -- do range analysis in such cases, but it could mean working with giant
8059 -- numbers at compile time for very little gain (the number of cases
8060 -- in which we could slip back from bignum mode is small).
8062 if Rlo = No_Uint or else (Binary and then Llo = No_Uint) then
8065 Bignum_Operands := True;
8067 -- Otherwise compute result range
8070 Bignum_Operands := False;
8078 Hi := UI_Max (abs Rlo, abs Rhi);
8090 -- If the right operand can only be zero, set 0..0
8092 if Rlo = 0 and then Rhi = 0 then
8096 -- Possible bounds of division must come from dividing end
8097 -- values of the input ranges (four possibilities), provided
8098 -- zero is not included in the possible values of the right
8101 -- Otherwise, we just consider two intervals of values for
8102 -- the right operand: the interval of negative values (up to
8103 -- -1) and the interval of positive values (starting at 1).
8104 -- Since division by 1 is the identity, and division by -1
8105 -- is negation, we get all possible bounds of division in that
8106 -- case by considering:
8107 -- - all values from the division of end values of input
8109 -- - the end values of the left operand;
8110 -- - the negation of the end values of the left operand.
8114 Mrk : constant Uintp.Save_Mark := Mark;
8115 -- Mark so we can release the RR and Ev values
8123 -- Discard extreme values of zero for the divisor, since
8124 -- they will simply result in an exception in any case.
8132 -- Compute possible bounds coming from dividing end
8133 -- values of the input ranges.
8140 Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4));
8141 Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4));
8143 -- If the right operand can be both negative or positive,
8144 -- include the end values of the left operand in the
8145 -- extreme values, as well as their negation.
8147 if Rlo < 0 and then Rhi > 0 then
8154 UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4)));
8156 UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4)));
8159 -- Release the RR and Ev values
8161 Release_And_Save (Mrk, Lo, Hi);
8169 -- Discard negative values for the exponent, since they will
8170 -- simply result in an exception in any case.
8178 -- Estimate number of bits in result before we go computing
8179 -- giant useless bounds. Basically the number of bits in the
8180 -- result is the number of bits in the base multiplied by the
8181 -- value of the exponent. If this is big enough that the result
8182 -- definitely won't fit in Long_Long_Integer, switch to bignum
8183 -- mode immediately, and avoid computing giant bounds.
8185 -- The comparison here is approximate, but conservative, it
8186 -- only clicks on cases that are sure to exceed the bounds.
8188 if Num_Bits (UI_Max (abs Llo, abs Lhi)) * Rhi + 1 > 100 then
8192 -- If right operand is zero then result is 1
8199 -- High bound comes either from exponentiation of largest
8200 -- positive value to largest exponent value, or from
8201 -- the exponentiation of most negative value to an
8215 if Rhi mod 2 = 0 then
8218 Hi2 := Llo ** (Rhi - 1);
8224 Hi := UI_Max (Hi1, Hi2);
8227 -- Result can only be negative if base can be negative
8230 if Rhi mod 2 = 0 then
8231 Lo := Llo ** (Rhi - 1);
8236 -- Otherwise low bound is minimum ** minimum
8253 Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1;
8254 -- This is the maximum absolute value of the result
8260 -- The result depends only on the sign and magnitude of
8261 -- the right operand, it does not depend on the sign or
8262 -- magnitude of the left operand.
8275 when N_Op_Multiply =>
8277 -- Possible bounds of multiplication must come from multiplying
8278 -- end values of the input ranges (four possibilities).
8281 Mrk : constant Uintp.Save_Mark := Mark;
8282 -- Mark so we can release the Ev values
8284 Ev1 : constant Uint := Llo * Rlo;
8285 Ev2 : constant Uint := Llo * Rhi;
8286 Ev3 : constant Uint := Lhi * Rlo;
8287 Ev4 : constant Uint := Lhi * Rhi;
8290 Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4));
8291 Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4));
8293 -- Release the Ev values
8295 Release_And_Save (Mrk, Lo, Hi);
8298 -- Plus operator (affirmation)
8308 Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1;
8309 -- This is the maximum absolute value of the result. Note
8310 -- that the result range does not depend on the sign of the
8317 -- Case of left operand negative, which results in a range
8318 -- of -Maxabs .. 0 for those negative values. If there are
8319 -- no negative values then Lo value of result is always 0.
8325 -- Case of left operand positive
8334 when N_Op_Subtract =>
8338 -- Nothing else should be possible
8341 raise Program_Error;
8345 -- Here for the case where we have not rewritten anything (no bignum
8346 -- operands or long long integer operands), and we know the result.
8347 -- If we know we are in the result range, and we do not have Bignum
8348 -- operands or Long_Long_Integer operands, we can just reexpand with
8349 -- overflow checks turned off (since we know we cannot have overflow).
8350 -- As always the reexpansion is required to complete expansion of the
8351 -- operator, but we do not need to reanalyze, and we prevent recursion
8352 -- by suppressing the check.
8354 if not (Bignum_Operands or Long_Long_Integer_Operands)
8355 and then In_Result_Range
8357 Set_Do_Overflow_Check (N, False);
8358 Reexpand (Suppress => True);
8361 -- Here we know that we are not in the result range, and in the general
8362 -- case we will move into either the Bignum or Long_Long_Integer domain
8363 -- to compute the result. However, there is one exception. If we are
8364 -- at the top level, and we do not have Bignum or Long_Long_Integer
8365 -- operands, we will have to immediately convert the result back to
8366 -- the result type, so there is no point in Bignum/Long_Long_Integer
8370 and then not (Bignum_Operands or Long_Long_Integer_Operands)
8372 -- One further refinement. If we are at the top level, but our parent
8373 -- is a type conversion, then go into bignum or long long integer node
8374 -- since the result will be converted to that type directly without
8375 -- going through the result type, and we may avoid an overflow. This
8376 -- is the case for example of Long_Long_Integer (A ** 4), where A is
8377 -- of type Integer, and the result A ** 4 fits in Long_Long_Integer
8378 -- but does not fit in Integer.
8380 and then Nkind (Parent (N)) /= N_Type_Conversion
8382 -- Here keep original types, but we need to complete analysis
8384 -- One subtlety. We can't just go ahead and do an analyze operation
8385 -- here because it will cause recursion into the whole MINIMIZED/
8386 -- ELIMINATED overflow processing which is not what we want. Here
8387 -- we are at the top level, and we need a check against the result
8388 -- mode (i.e. we want to use STRICT mode). So do exactly that.
8389 -- Also, we have not modified the node, so this is a case where
8390 -- we need to reexpand, but not reanalyze.
8395 -- Cases where we do the operation in Bignum mode. This happens either
8396 -- because one of our operands is in Bignum mode already, or because
8397 -- the computed bounds are outside the bounds of Long_Long_Integer,
8398 -- which in some cases can be indicated by Hi and Lo being No_Uint.
8400 -- Note: we could do better here and in some cases switch back from
8401 -- Bignum mode to normal mode, e.g. big mod 2 must be in the range
8402 -- 0 .. 1, but the cases are rare and it is not worth the effort.
8403 -- Failing to do this switching back is only an efficiency issue.
8405 elsif Lo = No_Uint or else Lo < LLLo or else Hi > LLHi then
8407 -- OK, we are definitely outside the range of Long_Long_Integer. The
8408 -- question is whether to move to Bignum mode, or stay in the domain
8409 -- of Long_Long_Integer, signalling that an overflow check is needed.
8411 -- Obviously in MINIMIZED mode we stay with LLI, since we are not in
8412 -- the Bignum business. In ELIMINATED mode, we will normally move
8413 -- into Bignum mode, but there is an exception if neither of our
8414 -- operands is Bignum now, and we are at the top level (Top_Level
8415 -- set True). In this case, there is no point in moving into Bignum
8416 -- mode to prevent overflow if the caller will immediately convert
8417 -- the Bignum value back to LLI with an overflow check. It's more
8418 -- efficient to stay in LLI mode with an overflow check (if needed)
8420 if Check_Mode = Minimized
8421 or else (Top_Level and not Bignum_Operands)
8423 if Do_Overflow_Check (N) then
8424 Enable_Overflow_Check (N);
8427 -- The result now has to be in Long_Long_Integer mode, so adjust
8428 -- the possible range to reflect this. Note these calls also
8429 -- change No_Uint values from the top level case to LLI bounds.
8434 -- Otherwise we are in ELIMINATED mode and we switch to Bignum mode
8437 pragma Assert (Check_Mode = Eliminated);
8446 Fent := RTE (RE_Big_Abs);
8449 Fent := RTE (RE_Big_Add);
8452 Fent := RTE (RE_Big_Div);
8455 Fent := RTE (RE_Big_Exp);
8458 Fent := RTE (RE_Big_Neg);
8461 Fent := RTE (RE_Big_Mod);
8463 when N_Op_Multiply =>
8464 Fent := RTE (RE_Big_Mul);
8467 Fent := RTE (RE_Big_Rem);
8469 when N_Op_Subtract =>
8470 Fent := RTE (RE_Big_Sub);
8472 -- Anything else is an internal error, this includes the
8473 -- N_Op_Plus case, since how can plus cause the result
8474 -- to be out of range if the operand is in range?
8477 raise Program_Error;
8480 -- Construct argument list for Bignum call, converting our
8481 -- operands to Bignum form if they are not already there.
8486 Append_To (Args, Convert_To_Bignum (Left_Opnd (N)));
8489 Append_To (Args, Convert_To_Bignum (Right_Opnd (N)));
8491 -- Now rewrite the arithmetic operator with a call to the
8492 -- corresponding bignum function.
8495 Make_Function_Call (Loc,
8496 Name => New_Occurrence_Of (Fent, Loc),
8497 Parameter_Associations => Args));
8498 Reanalyze (RTE (RE_Bignum), Suppress => True);
8500 -- Indicate result is Bignum mode
8508 -- Otherwise we are in range of Long_Long_Integer, so no overflow
8509 -- check is required, at least not yet.
8512 Set_Do_Overflow_Check (N, False);
8515 -- Here we are not in Bignum territory, but we may have long long
8516 -- integer operands that need special handling. First a special check:
8517 -- If an exponentiation operator exponent is of type Long_Long_Integer,
8518 -- it means we converted it to prevent overflow, but exponentiation
8519 -- requires a Natural right operand, so convert it back to Natural.
8520 -- This conversion may raise an exception which is fine.
8522 if Nkind (N) = N_Op_Expon and then Etype (Right_Opnd (N)) = LLIB then
8523 Convert_To_And_Rewrite (Standard_Natural, Right_Opnd (N));
8526 -- Here we will do the operation in Long_Long_Integer. We do this even
8527 -- if we know an overflow check is required, better to do this in long
8528 -- long integer mode, since we are less likely to overflow.
8530 -- Convert right or only operand to Long_Long_Integer, except that
8531 -- we do not touch the exponentiation right operand.
8533 if Nkind (N) /= N_Op_Expon then
8534 Convert_To_And_Rewrite (LLIB, Right_Opnd (N));
8537 -- Convert left operand to Long_Long_Integer for binary case
8540 Convert_To_And_Rewrite (LLIB, Left_Opnd (N));
8543 -- Reset node to unanalyzed
8545 Set_Analyzed (N, False);
8546 Set_Etype (N, Empty);
8547 Set_Entity (N, Empty);
8549 -- Now analyze this new node. This reanalysis will complete processing
8550 -- for the node. In particular we will complete the expansion of an
8551 -- exponentiation operator (e.g. changing A ** 2 to A * A), and also
8552 -- we will complete any division checks (since we have not changed the
8553 -- setting of the Do_Division_Check flag).
8555 -- We do this reanalysis in STRICT mode to avoid recursion into the
8556 -- MINIMIZED/ELIMINATED handling, since we are now done with that.
8559 SG : constant Overflow_Mode_Type :=
8560 Scope_Suppress.Overflow_Mode_General;
8561 SA : constant Overflow_Mode_Type :=
8562 Scope_Suppress.Overflow_Mode_Assertions;
8565 Scope_Suppress.Overflow_Mode_General := Strict;
8566 Scope_Suppress.Overflow_Mode_Assertions := Strict;
8568 if not Do_Overflow_Check (N) then
8569 Reanalyze (LLIB, Suppress => True);
8574 Scope_Suppress.Overflow_Mode_General := SG;
8575 Scope_Suppress.Overflow_Mode_Assertions := SA;
8577 end Minimize_Eliminate_Overflows;
8579 -------------------------
8580 -- Overflow_Check_Mode --
8581 -------------------------
8583 function Overflow_Check_Mode return Overflow_Mode_Type is
8585 if In_Assertion_Expr = 0 then
8586 return Scope_Suppress.Overflow_Mode_General;
8588 return Scope_Suppress.Overflow_Mode_Assertions;
8590 end Overflow_Check_Mode;
8592 --------------------------------
8593 -- Overflow_Checks_Suppressed --
8594 --------------------------------
8596 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
8598 if Present (E) and then Checks_May_Be_Suppressed (E) then
8599 return Is_Check_Suppressed (E, Overflow_Check);
8601 return Scope_Suppress.Suppress (Overflow_Check);
8603 end Overflow_Checks_Suppressed;
8605 ---------------------------------
8606 -- Predicate_Checks_Suppressed --
8607 ---------------------------------
8609 function Predicate_Checks_Suppressed (E : Entity_Id) return Boolean is
8611 if Present (E) and then Checks_May_Be_Suppressed (E) then
8612 return Is_Check_Suppressed (E, Predicate_Check);
8614 return Scope_Suppress.Suppress (Predicate_Check);
8616 end Predicate_Checks_Suppressed;
8618 -----------------------------
8619 -- Range_Checks_Suppressed --
8620 -----------------------------
8622 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
8625 if Kill_Range_Checks (E) then
8628 elsif Checks_May_Be_Suppressed (E) then
8629 return Is_Check_Suppressed (E, Range_Check);
8633 return Scope_Suppress.Suppress (Range_Check);
8634 end Range_Checks_Suppressed;
8636 -----------------------------------------
8637 -- Range_Or_Validity_Checks_Suppressed --
8638 -----------------------------------------
8640 -- Note: the coding would be simpler here if we simply made appropriate
8641 -- calls to Range/Validity_Checks_Suppressed, but that would result in
8642 -- duplicated checks which we prefer to avoid.
8644 function Range_Or_Validity_Checks_Suppressed
8645 (Expr : Node_Id) return Boolean
8648 -- Immediate return if scope checks suppressed for either check
8650 if Scope_Suppress.Suppress (Range_Check)
8652 Scope_Suppress.Suppress (Validity_Check)
8657 -- If no expression, that's odd, decide that checks are suppressed,
8658 -- since we don't want anyone trying to do checks in this case, which
8659 -- is most likely the result of some other error.
8665 -- Expression is present, so perform suppress checks on type
8668 Typ : constant Entity_Id := Etype (Expr);
8670 if Checks_May_Be_Suppressed (Typ)
8671 and then (Is_Check_Suppressed (Typ, Range_Check)
8673 Is_Check_Suppressed (Typ, Validity_Check))
8679 -- If expression is an entity name, perform checks on this entity
8681 if Is_Entity_Name (Expr) then
8683 Ent : constant Entity_Id := Entity (Expr);
8685 if Checks_May_Be_Suppressed (Ent) then
8686 return Is_Check_Suppressed (Ent, Range_Check)
8687 or else Is_Check_Suppressed (Ent, Validity_Check);
8692 -- If we fall through, no checks suppressed
8695 end Range_Or_Validity_Checks_Suppressed;
8701 procedure Remove_Checks (Expr : Node_Id) is
8702 function Process (N : Node_Id) return Traverse_Result;
8703 -- Process a single node during the traversal
8705 procedure Traverse is new Traverse_Proc (Process);
8706 -- The traversal procedure itself
8712 function Process (N : Node_Id) return Traverse_Result is
8714 if Nkind (N) not in N_Subexpr then
8718 Set_Do_Range_Check (N, False);
8722 Traverse (Left_Opnd (N));
8725 when N_Attribute_Reference =>
8726 Set_Do_Overflow_Check (N, False);
8728 when N_Function_Call =>
8729 Set_Do_Tag_Check (N, False);
8732 Set_Do_Overflow_Check (N, False);
8736 Set_Do_Division_Check (N, False);
8739 Set_Do_Length_Check (N, False);
8742 Set_Do_Division_Check (N, False);
8745 Set_Do_Length_Check (N, False);
8748 Set_Do_Division_Check (N, False);
8751 Set_Do_Length_Check (N, False);
8758 Traverse (Left_Opnd (N));
8761 when N_Selected_Component =>
8762 Set_Do_Discriminant_Check (N, False);
8764 when N_Type_Conversion =>
8765 Set_Do_Length_Check (N, False);
8766 Set_Do_Tag_Check (N, False);
8767 Set_Do_Overflow_Check (N, False);
8776 -- Start of processing for Remove_Checks
8782 ----------------------------
8783 -- Selected_Length_Checks --
8784 ----------------------------
8786 function Selected_Length_Checks
8788 Target_Typ : Entity_Id;
8789 Source_Typ : Entity_Id;
8790 Warn_Node : Node_Id) return Check_Result
8792 Loc : constant Source_Ptr := Sloc (Ck_Node);
8795 Expr_Actual : Node_Id;
8797 Cond : Node_Id := Empty;
8798 Do_Access : Boolean := False;
8799 Wnode : Node_Id := Warn_Node;
8800 Ret_Result : Check_Result := (Empty, Empty);
8801 Num_Checks : Natural := 0;
8803 procedure Add_Check (N : Node_Id);
8804 -- Adds the action given to Ret_Result if N is non-Empty
8806 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
8807 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
8808 -- Comments required ???
8810 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
8811 -- True for equal literals and for nodes that denote the same constant
8812 -- entity, even if its value is not a static constant. This includes the
8813 -- case of a discriminal reference within an init proc. Removes some
8814 -- obviously superfluous checks.
8816 function Length_E_Cond
8817 (Exptyp : Entity_Id;
8819 Indx : Nat) return Node_Id;
8820 -- Returns expression to compute:
8821 -- Typ'Length /= Exptyp'Length
8823 function Length_N_Cond
8826 Indx : Nat) return Node_Id;
8827 -- Returns expression to compute:
8828 -- Typ'Length /= Expr'Length
8834 procedure Add_Check (N : Node_Id) is
8838 -- For now, ignore attempt to place more than two checks ???
8839 -- This is really worrisome, are we really discarding checks ???
8841 if Num_Checks = 2 then
8845 pragma Assert (Num_Checks <= 1);
8846 Num_Checks := Num_Checks + 1;
8847 Ret_Result (Num_Checks) := N;
8855 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
8856 SE : constant Entity_Id := Scope (E);
8858 E1 : Entity_Id := E;
8861 if Ekind (Scope (E)) = E_Record_Type
8862 and then Has_Discriminants (Scope (E))
8864 N := Build_Discriminal_Subtype_Of_Component (E);
8867 Insert_Action (Ck_Node, N);
8868 E1 := Defining_Identifier (N);
8872 if Ekind (E1) = E_String_Literal_Subtype then
8874 Make_Integer_Literal (Loc,
8875 Intval => String_Literal_Length (E1));
8877 elsif SE /= Standard_Standard
8878 and then Ekind (Scope (SE)) = E_Protected_Type
8879 and then Has_Discriminants (Scope (SE))
8880 and then Has_Completion (Scope (SE))
8881 and then not Inside_Init_Proc
8883 -- If the type whose length is needed is a private component
8884 -- constrained by a discriminant, we must expand the 'Length
8885 -- attribute into an explicit computation, using the discriminal
8886 -- of the current protected operation. This is because the actual
8887 -- type of the prival is constructed after the protected opera-
8888 -- tion has been fully expanded.
8891 Indx_Type : Node_Id;
8894 Do_Expand : Boolean := False;
8897 Indx_Type := First_Index (E);
8899 for J in 1 .. Indx - 1 loop
8900 Next_Index (Indx_Type);
8903 Get_Index_Bounds (Indx_Type, Lo, Hi);
8905 if Nkind (Lo) = N_Identifier
8906 and then Ekind (Entity (Lo)) = E_In_Parameter
8908 Lo := Get_Discriminal (E, Lo);
8912 if Nkind (Hi) = N_Identifier
8913 and then Ekind (Entity (Hi)) = E_In_Parameter
8915 Hi := Get_Discriminal (E, Hi);
8920 if not Is_Entity_Name (Lo) then
8921 Lo := Duplicate_Subexpr_No_Checks (Lo);
8924 if not Is_Entity_Name (Hi) then
8925 Lo := Duplicate_Subexpr_No_Checks (Hi);
8931 Make_Op_Subtract (Loc,
8935 Right_Opnd => Make_Integer_Literal (Loc, 1));
8940 Make_Attribute_Reference (Loc,
8941 Attribute_Name => Name_Length,
8943 New_Occurrence_Of (E1, Loc));
8946 Set_Expressions (N, New_List (
8947 Make_Integer_Literal (Loc, Indx)));
8956 Make_Attribute_Reference (Loc,
8957 Attribute_Name => Name_Length,
8959 New_Occurrence_Of (E1, Loc));
8962 Set_Expressions (N, New_List (
8963 Make_Integer_Literal (Loc, Indx)));
8974 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
8977 Make_Attribute_Reference (Loc,
8978 Attribute_Name => Name_Length,
8980 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
8981 Expressions => New_List (
8982 Make_Integer_Literal (Loc, Indx)));
8989 function Length_E_Cond
8990 (Exptyp : Entity_Id;
8992 Indx : Nat) return Node_Id
8997 Left_Opnd => Get_E_Length (Typ, Indx),
8998 Right_Opnd => Get_E_Length (Exptyp, Indx));
9005 function Length_N_Cond
9008 Indx : Nat) return Node_Id
9013 Left_Opnd => Get_E_Length (Typ, Indx),
9014 Right_Opnd => Get_N_Length (Expr, Indx));
9021 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
9024 (Nkind (L) = N_Integer_Literal
9025 and then Nkind (R) = N_Integer_Literal
9026 and then Intval (L) = Intval (R))
9030 and then Ekind (Entity (L)) = E_Constant
9031 and then ((Is_Entity_Name (R)
9032 and then Entity (L) = Entity (R))
9034 (Nkind (R) = N_Type_Conversion
9035 and then Is_Entity_Name (Expression (R))
9036 and then Entity (L) = Entity (Expression (R)))))
9040 and then Ekind (Entity (R)) = E_Constant
9041 and then Nkind (L) = N_Type_Conversion
9042 and then Is_Entity_Name (Expression (L))
9043 and then Entity (R) = Entity (Expression (L)))
9047 and then Is_Entity_Name (R)
9048 and then Entity (L) = Entity (R)
9049 and then Ekind (Entity (L)) = E_In_Parameter
9050 and then Inside_Init_Proc);
9053 -- Start of processing for Selected_Length_Checks
9056 if not Expander_Active then
9060 if Target_Typ = Any_Type
9061 or else Target_Typ = Any_Composite
9062 or else Raises_Constraint_Error (Ck_Node)
9071 T_Typ := Target_Typ;
9073 if No (Source_Typ) then
9074 S_Typ := Etype (Ck_Node);
9076 S_Typ := Source_Typ;
9079 if S_Typ = Any_Type or else S_Typ = Any_Composite then
9083 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
9084 S_Typ := Designated_Type (S_Typ);
9085 T_Typ := Designated_Type (T_Typ);
9088 -- A simple optimization for the null case
9090 if Known_Null (Ck_Node) then
9095 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
9096 if Is_Constrained (T_Typ) then
9098 -- The checking code to be generated will freeze the corresponding
9099 -- array type. However, we must freeze the type now, so that the
9100 -- freeze node does not appear within the generated if expression,
9103 Freeze_Before (Ck_Node, T_Typ);
9105 Expr_Actual := Get_Referenced_Object (Ck_Node);
9106 Exptyp := Get_Actual_Subtype (Ck_Node);
9108 if Is_Access_Type (Exptyp) then
9109 Exptyp := Designated_Type (Exptyp);
9112 -- String_Literal case. This needs to be handled specially be-
9113 -- cause no index types are available for string literals. The
9114 -- condition is simply:
9116 -- T_Typ'Length = string-literal-length
9118 if Nkind (Expr_Actual) = N_String_Literal
9119 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
9123 Left_Opnd => Get_E_Length (T_Typ, 1),
9125 Make_Integer_Literal (Loc,
9127 String_Literal_Length (Etype (Expr_Actual))));
9129 -- General array case. Here we have a usable actual subtype for
9130 -- the expression, and the condition is built from the two types
9133 -- T_Typ'Length /= Exptyp'Length or else
9134 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
9135 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
9138 elsif Is_Constrained (Exptyp) then
9140 Ndims : constant Nat := Number_Dimensions (T_Typ);
9153 -- At the library level, we need to ensure that the type of
9154 -- the object is elaborated before the check itself is
9155 -- emitted. This is only done if the object is in the
9156 -- current compilation unit, otherwise the type is frozen
9157 -- and elaborated in its unit.
9159 if Is_Itype (Exptyp)
9161 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
9163 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
9164 and then In_Open_Scopes (Scope (Exptyp))
9166 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
9167 Set_Itype (Ref_Node, Exptyp);
9168 Insert_Action (Ck_Node, Ref_Node);
9171 L_Index := First_Index (T_Typ);
9172 R_Index := First_Index (Exptyp);
9174 for Indx in 1 .. Ndims loop
9175 if not (Nkind (L_Index) = N_Raise_Constraint_Error
9177 Nkind (R_Index) = N_Raise_Constraint_Error)
9179 Get_Index_Bounds (L_Index, L_Low, L_High);
9180 Get_Index_Bounds (R_Index, R_Low, R_High);
9182 -- Deal with compile time length check. Note that we
9183 -- skip this in the access case, because the access
9184 -- value may be null, so we cannot know statically.
9187 and then Compile_Time_Known_Value (L_Low)
9188 and then Compile_Time_Known_Value (L_High)
9189 and then Compile_Time_Known_Value (R_Low)
9190 and then Compile_Time_Known_Value (R_High)
9192 if Expr_Value (L_High) >= Expr_Value (L_Low) then
9193 L_Length := Expr_Value (L_High) -
9194 Expr_Value (L_Low) + 1;
9196 L_Length := UI_From_Int (0);
9199 if Expr_Value (R_High) >= Expr_Value (R_Low) then
9200 R_Length := Expr_Value (R_High) -
9201 Expr_Value (R_Low) + 1;
9203 R_Length := UI_From_Int (0);
9206 if L_Length > R_Length then
9208 (Compile_Time_Constraint_Error
9209 (Wnode, "too few elements for}??", T_Typ));
9211 elsif L_Length < R_Length then
9213 (Compile_Time_Constraint_Error
9214 (Wnode, "too many elements for}??", T_Typ));
9217 -- The comparison for an individual index subtype
9218 -- is omitted if the corresponding index subtypes
9219 -- statically match, since the result is known to
9220 -- be true. Note that this test is worth while even
9221 -- though we do static evaluation, because non-static
9222 -- subtypes can statically match.
9225 Subtypes_Statically_Match
9226 (Etype (L_Index), Etype (R_Index))
9229 (Same_Bounds (L_Low, R_Low)
9230 and then Same_Bounds (L_High, R_High))
9233 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
9242 -- Handle cases where we do not get a usable actual subtype that
9243 -- is constrained. This happens for example in the function call
9244 -- and explicit dereference cases. In these cases, we have to get
9245 -- the length or range from the expression itself, making sure we
9246 -- do not evaluate it more than once.
9248 -- Here Ck_Node is the original expression, or more properly the
9249 -- result of applying Duplicate_Expr to the original tree, forcing
9250 -- the result to be a name.
9254 Ndims : constant Nat := Number_Dimensions (T_Typ);
9257 -- Build the condition for the explicit dereference case
9259 for Indx in 1 .. Ndims loop
9261 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
9268 -- Construct the test and insert into the tree
9270 if Present (Cond) then
9272 Cond := Guard_Access (Cond, Loc, Ck_Node);
9276 (Make_Raise_Constraint_Error (Loc,
9278 Reason => CE_Length_Check_Failed));
9282 end Selected_Length_Checks;
9284 ---------------------------
9285 -- Selected_Range_Checks --
9286 ---------------------------
9288 function Selected_Range_Checks
9290 Target_Typ : Entity_Id;
9291 Source_Typ : Entity_Id;
9292 Warn_Node : Node_Id) return Check_Result
9294 Loc : constant Source_Ptr := Sloc (Ck_Node);
9297 Expr_Actual : Node_Id;
9299 Cond : Node_Id := Empty;
9300 Do_Access : Boolean := False;
9301 Wnode : Node_Id := Warn_Node;
9302 Ret_Result : Check_Result := (Empty, Empty);
9303 Num_Checks : Integer := 0;
9305 procedure Add_Check (N : Node_Id);
9306 -- Adds the action given to Ret_Result if N is non-Empty
9308 function Discrete_Range_Cond
9310 Typ : Entity_Id) return Node_Id;
9311 -- Returns expression to compute:
9312 -- Low_Bound (Expr) < Typ'First
9314 -- High_Bound (Expr) > Typ'Last
9316 function Discrete_Expr_Cond
9318 Typ : Entity_Id) return Node_Id;
9319 -- Returns expression to compute:
9324 function Get_E_First_Or_Last
9328 Nam : Name_Id) return Node_Id;
9329 -- Returns an attribute reference
9330 -- E'First or E'Last
9331 -- with a source location of Loc.
9333 -- Nam is Name_First or Name_Last, according to which attribute is
9334 -- desired. If Indx is non-zero, it is passed as a literal in the
9335 -- Expressions of the attribute reference (identifying the desired
9336 -- array dimension).
9338 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
9339 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
9340 -- Returns expression to compute:
9341 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
9343 function Range_E_Cond
9344 (Exptyp : Entity_Id;
9348 -- Returns expression to compute:
9349 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
9351 function Range_Equal_E_Cond
9352 (Exptyp : Entity_Id;
9354 Indx : Nat) return Node_Id;
9355 -- Returns expression to compute:
9356 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
9358 function Range_N_Cond
9361 Indx : Nat) return Node_Id;
9362 -- Return expression to compute:
9363 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
9369 procedure Add_Check (N : Node_Id) is
9373 -- For now, ignore attempt to place more than 2 checks ???
9375 if Num_Checks = 2 then
9379 pragma Assert (Num_Checks <= 1);
9380 Num_Checks := Num_Checks + 1;
9381 Ret_Result (Num_Checks) := N;
9385 -------------------------
9386 -- Discrete_Expr_Cond --
9387 -------------------------
9389 function Discrete_Expr_Cond
9391 Typ : Entity_Id) return Node_Id
9399 Convert_To (Base_Type (Typ),
9400 Duplicate_Subexpr_No_Checks (Expr)),
9402 Convert_To (Base_Type (Typ),
9403 Get_E_First_Or_Last (Loc, Typ, 0, Name_First))),
9408 Convert_To (Base_Type (Typ),
9409 Duplicate_Subexpr_No_Checks (Expr)),
9413 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last))));
9414 end Discrete_Expr_Cond;
9416 -------------------------
9417 -- Discrete_Range_Cond --
9418 -------------------------
9420 function Discrete_Range_Cond
9422 Typ : Entity_Id) return Node_Id
9424 LB : Node_Id := Low_Bound (Expr);
9425 HB : Node_Id := High_Bound (Expr);
9427 Left_Opnd : Node_Id;
9428 Right_Opnd : Node_Id;
9431 if Nkind (LB) = N_Identifier
9432 and then Ekind (Entity (LB)) = E_Discriminant
9434 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
9441 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
9446 Get_E_First_Or_Last (Loc, Typ, 0, Name_First)));
9448 if Nkind (HB) = N_Identifier
9449 and then Ekind (Entity (HB)) = E_Discriminant
9451 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
9458 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
9463 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last)));
9465 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
9466 end Discrete_Range_Cond;
9468 -------------------------
9469 -- Get_E_First_Or_Last --
9470 -------------------------
9472 function Get_E_First_Or_Last
9476 Nam : Name_Id) return Node_Id
9481 Exprs := New_List (Make_Integer_Literal (Loc, UI_From_Int (Indx)));
9486 return Make_Attribute_Reference (Loc,
9487 Prefix => New_Occurrence_Of (E, Loc),
9488 Attribute_Name => Nam,
9489 Expressions => Exprs);
9490 end Get_E_First_Or_Last;
9496 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
9499 Make_Attribute_Reference (Loc,
9500 Attribute_Name => Name_First,
9502 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
9503 Expressions => New_List (
9504 Make_Integer_Literal (Loc, Indx)));
9511 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
9514 Make_Attribute_Reference (Loc,
9515 Attribute_Name => Name_Last,
9517 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
9518 Expressions => New_List (
9519 Make_Integer_Literal (Loc, Indx)));
9526 function Range_E_Cond
9527 (Exptyp : Entity_Id;
9529 Indx : Nat) return Node_Id
9537 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
9539 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
9544 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
9546 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
9549 ------------------------
9550 -- Range_Equal_E_Cond --
9551 ------------------------
9553 function Range_Equal_E_Cond
9554 (Exptyp : Entity_Id;
9556 Indx : Nat) return Node_Id
9564 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
9566 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
9571 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
9573 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
9574 end Range_Equal_E_Cond;
9580 function Range_N_Cond
9583 Indx : Nat) return Node_Id
9591 Get_N_First (Expr, Indx),
9593 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
9598 Get_N_Last (Expr, Indx),
9600 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
9603 -- Start of processing for Selected_Range_Checks
9606 if not Expander_Active then
9610 if Target_Typ = Any_Type
9611 or else Target_Typ = Any_Composite
9612 or else Raises_Constraint_Error (Ck_Node)
9621 T_Typ := Target_Typ;
9623 if No (Source_Typ) then
9624 S_Typ := Etype (Ck_Node);
9626 S_Typ := Source_Typ;
9629 if S_Typ = Any_Type or else S_Typ = Any_Composite then
9633 -- The order of evaluating T_Typ before S_Typ seems to be critical
9634 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
9635 -- in, and since Node can be an N_Range node, it might be invalid.
9636 -- Should there be an assert check somewhere for taking the Etype of
9637 -- an N_Range node ???
9639 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
9640 S_Typ := Designated_Type (S_Typ);
9641 T_Typ := Designated_Type (T_Typ);
9644 -- A simple optimization for the null case
9646 if Known_Null (Ck_Node) then
9651 -- For an N_Range Node, check for a null range and then if not
9652 -- null generate a range check action.
9654 if Nkind (Ck_Node) = N_Range then
9656 -- There's no point in checking a range against itself
9658 if Ck_Node = Scalar_Range (T_Typ) then
9663 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
9664 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
9665 Known_T_LB : constant Boolean := Compile_Time_Known_Value (T_LB);
9666 Known_T_HB : constant Boolean := Compile_Time_Known_Value (T_HB);
9668 LB : Node_Id := Low_Bound (Ck_Node);
9669 HB : Node_Id := High_Bound (Ck_Node);
9670 Known_LB : Boolean := False;
9671 Known_HB : Boolean := False;
9673 Null_Range : Boolean;
9674 Out_Of_Range_L : Boolean;
9675 Out_Of_Range_H : Boolean;
9678 -- Compute what is known at compile time
9680 if Known_T_LB and Known_T_HB then
9681 if Compile_Time_Known_Value (LB) then
9684 -- There's no point in checking that a bound is within its
9685 -- own range so pretend that it is known in this case. First
9686 -- deal with low bound.
9688 elsif Ekind (Etype (LB)) = E_Signed_Integer_Subtype
9689 and then Scalar_Range (Etype (LB)) = Scalar_Range (T_Typ)
9695 -- Likewise for the high bound
9697 if Compile_Time_Known_Value (HB) then
9700 elsif Ekind (Etype (HB)) = E_Signed_Integer_Subtype
9701 and then Scalar_Range (Etype (HB)) = Scalar_Range (T_Typ)
9708 -- Check for case where everything is static and we can do the
9709 -- check at compile time. This is skipped if we have an access
9710 -- type, since the access value may be null.
9712 -- ??? This code can be improved since you only need to know that
9713 -- the two respective bounds (LB & T_LB or HB & T_HB) are known at
9714 -- compile time to emit pertinent messages.
9716 if Known_T_LB and Known_T_HB and Known_LB and Known_HB
9719 -- Floating-point case
9721 if Is_Floating_Point_Type (S_Typ) then
9722 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
9724 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
9726 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
9729 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
9731 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
9733 -- Fixed or discrete type case
9736 Null_Range := Expr_Value (HB) < Expr_Value (LB);
9738 (Expr_Value (LB) < Expr_Value (T_LB))
9740 (Expr_Value (LB) > Expr_Value (T_HB));
9743 (Expr_Value (HB) > Expr_Value (T_HB))
9745 (Expr_Value (HB) < Expr_Value (T_LB));
9748 if not Null_Range then
9749 if Out_Of_Range_L then
9750 if No (Warn_Node) then
9752 (Compile_Time_Constraint_Error
9753 (Low_Bound (Ck_Node),
9754 "static value out of range of}??", T_Typ));
9758 (Compile_Time_Constraint_Error
9760 "static range out of bounds of}??", T_Typ));
9764 if Out_Of_Range_H then
9765 if No (Warn_Node) then
9767 (Compile_Time_Constraint_Error
9768 (High_Bound (Ck_Node),
9769 "static value out of range of}??", T_Typ));
9773 (Compile_Time_Constraint_Error
9775 "static range out of bounds of}??", T_Typ));
9782 LB : Node_Id := Low_Bound (Ck_Node);
9783 HB : Node_Id := High_Bound (Ck_Node);
9786 -- If either bound is a discriminant and we are within the
9787 -- record declaration, it is a use of the discriminant in a
9788 -- constraint of a component, and nothing can be checked
9789 -- here. The check will be emitted within the init proc.
9790 -- Before then, the discriminal has no real meaning.
9791 -- Similarly, if the entity is a discriminal, there is no
9792 -- check to perform yet.
9794 -- The same holds within a discriminated synchronized type,
9795 -- where the discriminant may constrain a component or an
9798 if Nkind (LB) = N_Identifier
9799 and then Denotes_Discriminant (LB, True)
9801 if Current_Scope = Scope (Entity (LB))
9802 or else Is_Concurrent_Type (Current_Scope)
9803 or else Ekind (Entity (LB)) /= E_Discriminant
9808 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
9812 if Nkind (HB) = N_Identifier
9813 and then Denotes_Discriminant (HB, True)
9815 if Current_Scope = Scope (Entity (HB))
9816 or else Is_Concurrent_Type (Current_Scope)
9817 or else Ekind (Entity (HB)) /= E_Discriminant
9822 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
9826 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
9827 Set_Paren_Count (Cond, 1);
9834 Convert_To (Base_Type (Etype (HB)),
9835 Duplicate_Subexpr_No_Checks (HB)),
9837 Convert_To (Base_Type (Etype (LB)),
9838 Duplicate_Subexpr_No_Checks (LB))),
9839 Right_Opnd => Cond);
9844 elsif Is_Scalar_Type (S_Typ) then
9846 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
9847 -- except the above simply sets a flag in the node and lets
9848 -- gigi generate the check base on the Etype of the expression.
9849 -- Sometimes, however we want to do a dynamic check against an
9850 -- arbitrary target type, so we do that here.
9852 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
9853 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9855 -- For literals, we can tell if the constraint error will be
9856 -- raised at compile time, so we never need a dynamic check, but
9857 -- if the exception will be raised, then post the usual warning,
9858 -- and replace the literal with a raise constraint error
9859 -- expression. As usual, skip this for access types
9861 elsif Compile_Time_Known_Value (Ck_Node) and then not Do_Access then
9863 LB : constant Node_Id := Type_Low_Bound (T_Typ);
9864 UB : constant Node_Id := Type_High_Bound (T_Typ);
9866 Out_Of_Range : Boolean;
9867 Static_Bounds : constant Boolean :=
9868 Compile_Time_Known_Value (LB)
9869 and Compile_Time_Known_Value (UB);
9872 -- Following range tests should use Sem_Eval routine ???
9874 if Static_Bounds then
9875 if Is_Floating_Point_Type (S_Typ) then
9877 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
9879 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
9881 -- Fixed or discrete type
9885 Expr_Value (Ck_Node) < Expr_Value (LB)
9887 Expr_Value (Ck_Node) > Expr_Value (UB);
9890 -- Bounds of the type are static and the literal is out of
9891 -- range so output a warning message.
9893 if Out_Of_Range then
9894 if No (Warn_Node) then
9896 (Compile_Time_Constraint_Error
9898 "static value out of range of}??", T_Typ));
9902 (Compile_Time_Constraint_Error
9904 "static value out of range of}??", T_Typ));
9909 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9913 -- Here for the case of a non-static expression, we need a runtime
9914 -- check unless the source type range is guaranteed to be in the
9915 -- range of the target type.
9918 if not In_Subrange_Of (S_Typ, T_Typ) then
9919 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9924 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
9925 if Is_Constrained (T_Typ) then
9927 Expr_Actual := Get_Referenced_Object (Ck_Node);
9928 Exptyp := Get_Actual_Subtype (Expr_Actual);
9930 if Is_Access_Type (Exptyp) then
9931 Exptyp := Designated_Type (Exptyp);
9934 -- String_Literal case. This needs to be handled specially be-
9935 -- cause no index types are available for string literals. The
9936 -- condition is simply:
9938 -- T_Typ'Length = string-literal-length
9940 if Nkind (Expr_Actual) = N_String_Literal then
9943 -- General array case. Here we have a usable actual subtype for
9944 -- the expression, and the condition is built from the two types
9946 -- T_Typ'First < Exptyp'First or else
9947 -- T_Typ'Last > Exptyp'Last or else
9948 -- T_Typ'First(1) < Exptyp'First(1) or else
9949 -- T_Typ'Last(1) > Exptyp'Last(1) or else
9952 elsif Is_Constrained (Exptyp) then
9954 Ndims : constant Nat := Number_Dimensions (T_Typ);
9960 L_Index := First_Index (T_Typ);
9961 R_Index := First_Index (Exptyp);
9963 for Indx in 1 .. Ndims loop
9964 if not (Nkind (L_Index) = N_Raise_Constraint_Error
9966 Nkind (R_Index) = N_Raise_Constraint_Error)
9968 -- Deal with compile time length check. Note that we
9969 -- skip this in the access case, because the access
9970 -- value may be null, so we cannot know statically.
9973 Subtypes_Statically_Match
9974 (Etype (L_Index), Etype (R_Index))
9976 -- If the target type is constrained then we
9977 -- have to check for exact equality of bounds
9978 -- (required for qualified expressions).
9980 if Is_Constrained (T_Typ) then
9983 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
9986 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
9996 -- Handle cases where we do not get a usable actual subtype that
9997 -- is constrained. This happens for example in the function call
9998 -- and explicit dereference cases. In these cases, we have to get
9999 -- the length or range from the expression itself, making sure we
10000 -- do not evaluate it more than once.
10002 -- Here Ck_Node is the original expression, or more properly the
10003 -- result of applying Duplicate_Expr to the original tree,
10004 -- forcing the result to be a name.
10008 Ndims : constant Nat := Number_Dimensions (T_Typ);
10011 -- Build the condition for the explicit dereference case
10013 for Indx in 1 .. Ndims loop
10015 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
10021 -- For a conversion to an unconstrained array type, generate an
10022 -- Action to check that the bounds of the source value are within
10023 -- the constraints imposed by the target type (RM 4.6(38)). No
10024 -- check is needed for a conversion to an access to unconstrained
10025 -- array type, as 4.6(24.15/2) requires the designated subtypes
10026 -- of the two access types to statically match.
10028 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
10029 and then not Do_Access
10032 Opnd_Index : Node_Id;
10033 Targ_Index : Node_Id;
10034 Opnd_Range : Node_Id;
10037 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
10038 Targ_Index := First_Index (T_Typ);
10039 while Present (Opnd_Index) loop
10041 -- If the index is a range, use its bounds. If it is an
10042 -- entity (as will be the case if it is a named subtype
10043 -- or an itype created for a slice) retrieve its range.
10045 if Is_Entity_Name (Opnd_Index)
10046 and then Is_Type (Entity (Opnd_Index))
10048 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
10050 Opnd_Range := Opnd_Index;
10053 if Nkind (Opnd_Range) = N_Range then
10055 (Low_Bound (Opnd_Range), Etype (Targ_Index),
10056 Assume_Valid => True)
10059 (High_Bound (Opnd_Range), Etype (Targ_Index),
10060 Assume_Valid => True)
10064 -- If null range, no check needed
10067 Compile_Time_Known_Value (High_Bound (Opnd_Range))
10069 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
10071 Expr_Value (High_Bound (Opnd_Range)) <
10072 Expr_Value (Low_Bound (Opnd_Range))
10076 elsif Is_Out_Of_Range
10077 (Low_Bound (Opnd_Range), Etype (Targ_Index),
10078 Assume_Valid => True)
10081 (High_Bound (Opnd_Range), Etype (Targ_Index),
10082 Assume_Valid => True)
10085 (Compile_Time_Constraint_Error
10086 (Wnode, "value out of range of}??", T_Typ));
10091 Discrete_Range_Cond
10092 (Opnd_Range, Etype (Targ_Index)));
10096 Next_Index (Opnd_Index);
10097 Next_Index (Targ_Index);
10104 -- Construct the test and insert into the tree
10106 if Present (Cond) then
10108 Cond := Guard_Access (Cond, Loc, Ck_Node);
10112 (Make_Raise_Constraint_Error (Loc,
10114 Reason => CE_Range_Check_Failed));
10118 end Selected_Range_Checks;
10120 -------------------------------
10121 -- Storage_Checks_Suppressed --
10122 -------------------------------
10124 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
10126 if Present (E) and then Checks_May_Be_Suppressed (E) then
10127 return Is_Check_Suppressed (E, Storage_Check);
10129 return Scope_Suppress.Suppress (Storage_Check);
10131 end Storage_Checks_Suppressed;
10133 ---------------------------
10134 -- Tag_Checks_Suppressed --
10135 ---------------------------
10137 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
10140 and then Checks_May_Be_Suppressed (E)
10142 return Is_Check_Suppressed (E, Tag_Check);
10144 return Scope_Suppress.Suppress (Tag_Check);
10146 end Tag_Checks_Suppressed;
10148 ---------------------------------------
10149 -- Validate_Alignment_Check_Warnings --
10150 ---------------------------------------
10152 procedure Validate_Alignment_Check_Warnings is
10154 for J in Alignment_Warnings.First .. Alignment_Warnings.Last loop
10156 AWR : Alignment_Warnings_Record
10157 renames Alignment_Warnings.Table (J);
10159 if Known_Alignment (AWR.E)
10160 and then AWR.A mod Alignment (AWR.E) = 0
10162 Delete_Warning_And_Continuations (AWR.W);
10166 end Validate_Alignment_Check_Warnings;
10168 --------------------------
10169 -- Validity_Check_Range --
10170 --------------------------
10172 procedure Validity_Check_Range
10174 Related_Id : Entity_Id := Empty)
10177 if Validity_Checks_On and Validity_Check_Operands then
10178 if Nkind (N) = N_Range then
10180 (Expr => Low_Bound (N),
10181 Related_Id => Related_Id,
10182 Is_Low_Bound => True);
10185 (Expr => High_Bound (N),
10186 Related_Id => Related_Id,
10187 Is_High_Bound => True);
10190 end Validity_Check_Range;
10192 --------------------------------
10193 -- Validity_Checks_Suppressed --
10194 --------------------------------
10196 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
10198 if Present (E) and then Checks_May_Be_Suppressed (E) then
10199 return Is_Check_Suppressed (E, Validity_Check);
10201 return Scope_Suppress.Suppress (Validity_Check);
10203 end Validity_Checks_Suppressed;