1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2013, 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 Errout; use Errout;
31 with Exp_Ch2; use Exp_Ch2;
32 with Exp_Ch4; use Exp_Ch4;
33 with Exp_Ch11; use Exp_Ch11;
34 with Exp_Pakd; use Exp_Pakd;
35 with Exp_Tss; use Exp_Tss;
36 with Exp_Util; use Exp_Util;
37 with Elists; use Elists;
38 with Expander; use Expander;
39 with Eval_Fat; use Eval_Fat;
40 with Freeze; use Freeze;
42 with Nlists; use Nlists;
43 with Nmake; use Nmake;
45 with Output; use Output;
46 with Restrict; use Restrict;
47 with Rident; use Rident;
48 with Rtsfind; use Rtsfind;
50 with Sem_Aux; use Sem_Aux;
51 with Sem_Eval; use Sem_Eval;
52 with Sem_Ch3; use Sem_Ch3;
53 with Sem_Ch8; use Sem_Ch8;
54 with Sem_Res; use Sem_Res;
55 with Sem_Util; use Sem_Util;
56 with Sem_Warn; use Sem_Warn;
57 with Sinfo; use Sinfo;
58 with Sinput; use Sinput;
59 with Snames; use Snames;
60 with Sprint; use Sprint;
61 with Stand; use Stand;
62 with Stringt; use Stringt;
63 with Targparm; use Targparm;
64 with Tbuild; use Tbuild;
65 with Ttypes; use Ttypes;
66 with Urealp; use Urealp;
67 with Validsw; use Validsw;
69 package body Checks is
71 -- General note: many of these routines are concerned with generating
72 -- checking code to make sure that constraint error is raised at runtime.
73 -- Clearly this code is only needed if the expander is active, since
74 -- otherwise we will not be generating code or going into the runtime
77 -- We therefore disconnect most of these checks if the expander is
78 -- inactive. This has the additional benefit that we do not need to
79 -- worry about the tree being messed up by previous errors (since errors
80 -- turn off expansion anyway).
82 -- There are a few exceptions to the above rule. For instance routines
83 -- such as Apply_Scalar_Range_Check that do not insert any code can be
84 -- safely called even when the Expander is inactive (but Errors_Detected
85 -- is 0). The benefit of executing this code when expansion is off, is
86 -- the ability to emit constraint error warning for static expressions
87 -- even when we are not generating code.
89 -------------------------------------
90 -- Suppression of Redundant Checks --
91 -------------------------------------
93 -- This unit implements a limited circuit for removal of redundant
94 -- checks. The processing is based on a tracing of simple sequential
95 -- flow. For any sequence of statements, we save expressions that are
96 -- marked to be checked, and then if the same expression appears later
97 -- with the same check, then under certain circumstances, the second
98 -- check can be suppressed.
100 -- Basically, we can suppress the check if we know for certain that
101 -- the previous expression has been elaborated (together with its
102 -- check), and we know that the exception frame is the same, and that
103 -- nothing has happened to change the result of the exception.
105 -- Let us examine each of these three conditions in turn to describe
106 -- how we ensure that this condition is met.
108 -- First, we need to know for certain that the previous expression has
109 -- been executed. This is done principally by the mechanism of calling
110 -- Conditional_Statements_Begin at the start of any statement sequence
111 -- and Conditional_Statements_End at the end. The End call causes all
112 -- checks remembered since the Begin call to be discarded. This does
113 -- miss a few cases, notably the case of a nested BEGIN-END block with
114 -- no exception handlers. But the important thing is to be conservative.
115 -- The other protection is that all checks are discarded if a label
116 -- is encountered, since then the assumption of sequential execution
117 -- is violated, and we don't know enough about the flow.
119 -- Second, we need to know that the exception frame is the same. We
120 -- do this by killing all remembered checks when we enter a new frame.
121 -- Again, that's over-conservative, but generally the cases we can help
122 -- with are pretty local anyway (like the body of a loop for example).
124 -- Third, we must be sure to forget any checks which are no longer valid.
125 -- This is done by two mechanisms, first the Kill_Checks_Variable call is
126 -- used to note any changes to local variables. We only attempt to deal
127 -- with checks involving local variables, so we do not need to worry
128 -- about global variables. Second, a call to any non-global procedure
129 -- causes us to abandon all stored checks, since such a all may affect
130 -- the values of any local variables.
132 -- The following define the data structures used to deal with remembering
133 -- checks so that redundant checks can be eliminated as described above.
135 -- Right now, the only expressions that we deal with are of the form of
136 -- simple local objects (either declared locally, or IN parameters) or
137 -- such objects plus/minus a compile time known constant. We can do
138 -- more later on if it seems worthwhile, but this catches many simple
139 -- cases in practice.
141 -- The following record type reflects a single saved check. An entry
142 -- is made in the stack of saved checks if and only if the expression
143 -- has been elaborated with the indicated checks.
145 type Saved_Check is record
147 -- Set True if entry is killed by Kill_Checks
150 -- The entity involved in the expression that is checked
153 -- A compile time value indicating the result of adding or
154 -- subtracting a compile time value. This value is to be
155 -- added to the value of the Entity. A value of zero is
156 -- used for the case of a simple entity reference.
158 Check_Type : Character;
159 -- This is set to 'R' for a range check (in which case Target_Type
160 -- is set to the target type for the range check) or to 'O' for an
161 -- overflow check (in which case Target_Type is set to Empty).
163 Target_Type : Entity_Id;
164 -- Used only if Do_Range_Check is set. Records the target type for
165 -- the check. We need this, because a check is a duplicate only if
166 -- it has the same target type (or more accurately one with a
167 -- range that is smaller or equal to the stored target type of a
171 -- The following table keeps track of saved checks. Rather than use an
172 -- extensible table. We just use a table of fixed size, and we discard
173 -- any saved checks that do not fit. That's very unlikely to happen and
174 -- this is only an optimization in any case.
176 Saved_Checks : array (Int range 1 .. 200) of Saved_Check;
177 -- Array of saved checks
179 Num_Saved_Checks : Nat := 0;
180 -- Number of saved checks
182 -- The following stack keeps track of statement ranges. It is treated
183 -- as a stack. When Conditional_Statements_Begin is called, an entry
184 -- is pushed onto this stack containing the value of Num_Saved_Checks
185 -- at the time of the call. Then when Conditional_Statements_End is
186 -- called, this value is popped off and used to reset Num_Saved_Checks.
188 -- Note: again, this is a fixed length stack with a size that should
189 -- always be fine. If the value of the stack pointer goes above the
190 -- limit, then we just forget all saved checks.
192 Saved_Checks_Stack : array (Int range 1 .. 100) of Nat;
193 Saved_Checks_TOS : Nat := 0;
195 -----------------------
196 -- Local Subprograms --
197 -----------------------
199 procedure Apply_Arithmetic_Overflow_Strict (N : Node_Id);
200 -- Used to apply arithmetic overflow checks for all cases except operators
201 -- on signed arithmetic types in MINIMIZED/ELIMINATED case (for which we
202 -- call Apply_Arithmetic_Overflow_Minimized_Eliminated below). N can be a
203 -- signed integer arithmetic operator (but not an if or case expression).
204 -- It is also called for types other than signed integers.
206 procedure Apply_Arithmetic_Overflow_Minimized_Eliminated (Op : Node_Id);
207 -- Used to apply arithmetic overflow checks for the case where the overflow
208 -- checking mode is MINIMIZED or ELIMINATED and we have a signed integer
209 -- arithmetic op (which includes the case of if and case expressions). Note
210 -- that Do_Overflow_Check may or may not be set for node Op. In these modes
211 -- we have work to do even if overflow checking is suppressed.
213 procedure Apply_Division_Check
218 -- N is an N_Op_Div, N_Op_Rem, or N_Op_Mod node. This routine applies
219 -- division checks as required if the Do_Division_Check flag is set.
220 -- Rlo and Rhi give the possible range of the right operand, these values
221 -- can be referenced and trusted only if ROK is set True.
223 procedure Apply_Float_Conversion_Check
225 Target_Typ : Entity_Id);
226 -- The checks on a conversion from a floating-point type to an integer
227 -- type are delicate. They have to be performed before conversion, they
228 -- have to raise an exception when the operand is a NaN, and rounding must
229 -- be taken into account to determine the safe bounds of the operand.
231 procedure Apply_Selected_Length_Checks
233 Target_Typ : Entity_Id;
234 Source_Typ : Entity_Id;
235 Do_Static : Boolean);
236 -- This is the subprogram that does all the work for Apply_Length_Check
237 -- and Apply_Static_Length_Check. Expr, Target_Typ and Source_Typ are as
238 -- described for the above routines. The Do_Static flag indicates that
239 -- only a static check is to be done.
241 procedure Apply_Selected_Range_Checks
243 Target_Typ : Entity_Id;
244 Source_Typ : Entity_Id;
245 Do_Static : Boolean);
246 -- This is the subprogram that does all the work for Apply_Range_Check.
247 -- Expr, Target_Typ and Source_Typ are as described for the above
248 -- routine. The Do_Static flag indicates that only a static check is
251 type Check_Type is new Check_Id range Access_Check .. Division_Check;
252 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean;
253 -- This function is used to see if an access or division by zero check is
254 -- needed. The check is to be applied to a single variable appearing in the
255 -- source, and N is the node for the reference. If N is not of this form,
256 -- True is returned with no further processing. If N is of the right form,
257 -- then further processing determines if the given Check is needed.
259 -- The particular circuit is to see if we have the case of a check that is
260 -- not needed because it appears in the right operand of a short circuited
261 -- conditional where the left operand guards the check. For example:
263 -- if Var = 0 or else Q / Var > 12 then
267 -- In this example, the division check is not required. At the same time
268 -- we can issue warnings for suspicious use of non-short-circuited forms,
271 -- if Var = 0 or Q / Var > 12 then
277 Check_Type : Character;
278 Target_Type : Entity_Id;
279 Entry_OK : out Boolean;
283 -- This routine is used by Enable_Range_Check and Enable_Overflow_Check
284 -- to see if a check is of the form for optimization, and if so, to see
285 -- if it has already been performed. Expr is the expression to check,
286 -- and Check_Type is 'R' for a range check, 'O' for an overflow check.
287 -- Target_Type is the target type for a range check, and Empty for an
288 -- overflow check. If the entry is not of the form for optimization,
289 -- then Entry_OK is set to False, and the remaining out parameters
290 -- are undefined. If the entry is OK, then Ent/Ofs are set to the
291 -- entity and offset from the expression. Check_Num is the number of
292 -- a matching saved entry in Saved_Checks, or zero if no such entry
295 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id;
296 -- If a discriminal is used in constraining a prival, Return reference
297 -- to the discriminal of the protected body (which renames the parameter
298 -- of the enclosing protected operation). This clumsy transformation is
299 -- needed because privals are created too late and their actual subtypes
300 -- are not available when analysing the bodies of the protected operations.
301 -- This function is called whenever the bound is an entity and the scope
302 -- indicates a protected operation. If the bound is an in-parameter of
303 -- a protected operation that is not a prival, the function returns the
305 -- To be cleaned up???
307 function Guard_Access
310 Ck_Node : Node_Id) return Node_Id;
311 -- In the access type case, guard the test with a test to ensure
312 -- that the access value is non-null, since the checks do not
313 -- not apply to null access values.
315 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr);
316 -- Called by Apply_{Length,Range}_Checks to rewrite the tree with the
317 -- Constraint_Error node.
319 function Is_Signed_Integer_Arithmetic_Op (N : Node_Id) return Boolean;
320 -- Returns True if node N is for an arithmetic operation with signed
321 -- integer operands. This includes unary and binary operators, and also
322 -- if and case expression nodes where the dependent expressions are of
323 -- a signed integer type. These are the kinds of nodes for which special
324 -- handling applies in MINIMIZED or ELIMINATED overflow checking mode.
326 function Range_Or_Validity_Checks_Suppressed
327 (Expr : Node_Id) return Boolean;
328 -- Returns True if either range or validity checks or both are suppressed
329 -- for the type of the given expression, or, if the expression is the name
330 -- of an entity, if these checks are suppressed for the entity.
332 function Selected_Length_Checks
334 Target_Typ : Entity_Id;
335 Source_Typ : Entity_Id;
336 Warn_Node : Node_Id) return Check_Result;
337 -- Like Apply_Selected_Length_Checks, except it doesn't modify
338 -- anything, just returns a list of nodes as described in the spec of
339 -- this package for the Range_Check function.
341 function Selected_Range_Checks
343 Target_Typ : Entity_Id;
344 Source_Typ : Entity_Id;
345 Warn_Node : Node_Id) return Check_Result;
346 -- Like Apply_Selected_Range_Checks, except it doesn't modify anything,
347 -- just returns a list of nodes as described in the spec of this package
348 -- for the Range_Check function.
350 ------------------------------
351 -- Access_Checks_Suppressed --
352 ------------------------------
354 function Access_Checks_Suppressed (E : Entity_Id) return Boolean is
356 if Present (E) and then Checks_May_Be_Suppressed (E) then
357 return Is_Check_Suppressed (E, Access_Check);
359 return Scope_Suppress.Suppress (Access_Check);
361 end Access_Checks_Suppressed;
363 -------------------------------------
364 -- Accessibility_Checks_Suppressed --
365 -------------------------------------
367 function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean is
369 if Present (E) and then Checks_May_Be_Suppressed (E) then
370 return Is_Check_Suppressed (E, Accessibility_Check);
372 return Scope_Suppress.Suppress (Accessibility_Check);
374 end Accessibility_Checks_Suppressed;
376 -----------------------------
377 -- Activate_Division_Check --
378 -----------------------------
380 procedure Activate_Division_Check (N : Node_Id) is
382 Set_Do_Division_Check (N, True);
383 Possible_Local_Raise (N, Standard_Constraint_Error);
384 end Activate_Division_Check;
386 -----------------------------
387 -- Activate_Overflow_Check --
388 -----------------------------
390 procedure Activate_Overflow_Check (N : Node_Id) is
392 if not Nkind_In (N, N_Op_Rem, N_Op_Mod, N_Op_Plus) then
393 Set_Do_Overflow_Check (N, True);
394 Possible_Local_Raise (N, Standard_Constraint_Error);
396 end Activate_Overflow_Check;
398 --------------------------
399 -- Activate_Range_Check --
400 --------------------------
402 procedure Activate_Range_Check (N : Node_Id) is
404 Set_Do_Range_Check (N, True);
405 Possible_Local_Raise (N, Standard_Constraint_Error);
406 end Activate_Range_Check;
408 ---------------------------------
409 -- Alignment_Checks_Suppressed --
410 ---------------------------------
412 function Alignment_Checks_Suppressed (E : Entity_Id) return Boolean is
414 if Present (E) and then Checks_May_Be_Suppressed (E) then
415 return Is_Check_Suppressed (E, Alignment_Check);
417 return Scope_Suppress.Suppress (Alignment_Check);
419 end Alignment_Checks_Suppressed;
421 -------------------------
422 -- Append_Range_Checks --
423 -------------------------
425 procedure Append_Range_Checks
426 (Checks : Check_Result;
428 Suppress_Typ : Entity_Id;
429 Static_Sloc : Source_Ptr;
432 Internal_Flag_Node : constant Node_Id := Flag_Node;
433 Internal_Static_Sloc : constant Source_Ptr := Static_Sloc;
435 Checks_On : constant Boolean :=
436 (not Index_Checks_Suppressed (Suppress_Typ))
437 or else (not Range_Checks_Suppressed (Suppress_Typ));
440 -- For now we just return if Checks_On is false, however this should
441 -- be enhanced to check for an always True value in the condition
442 -- and to generate a compilation warning???
444 if not Checks_On then
449 exit when No (Checks (J));
451 if Nkind (Checks (J)) = N_Raise_Constraint_Error
452 and then Present (Condition (Checks (J)))
454 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
455 Append_To (Stmts, Checks (J));
456 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
462 Make_Raise_Constraint_Error (Internal_Static_Sloc,
463 Reason => CE_Range_Check_Failed));
466 end Append_Range_Checks;
468 ------------------------
469 -- Apply_Access_Check --
470 ------------------------
472 procedure Apply_Access_Check (N : Node_Id) is
473 P : constant Node_Id := Prefix (N);
476 -- We do not need checks if we are not generating code (i.e. the
477 -- expander is not active). This is not just an optimization, there
478 -- are cases (e.g. with pragma Debug) where generating the checks
479 -- can cause real trouble).
481 if not Expander_Active then
485 -- No check if short circuiting makes check unnecessary
487 if not Check_Needed (P, Access_Check) then
491 -- No check if accessing the Offset_To_Top component of a dispatch
492 -- table. They are safe by construction.
494 if Tagged_Type_Expansion
495 and then Present (Etype (P))
496 and then RTU_Loaded (Ada_Tags)
497 and then RTE_Available (RE_Offset_To_Top_Ptr)
498 and then Etype (P) = RTE (RE_Offset_To_Top_Ptr)
503 -- Otherwise go ahead and install the check
505 Install_Null_Excluding_Check (P);
506 end Apply_Access_Check;
508 -------------------------------
509 -- Apply_Accessibility_Check --
510 -------------------------------
512 procedure Apply_Accessibility_Check
515 Insert_Node : Node_Id)
517 Loc : constant Source_Ptr := Sloc (N);
518 Param_Ent : Entity_Id := Param_Entity (N);
519 Param_Level : Node_Id;
520 Type_Level : Node_Id;
523 if Ada_Version >= Ada_2012
524 and then not Present (Param_Ent)
525 and then Is_Entity_Name (N)
526 and then Ekind_In (Entity (N), E_Constant, E_Variable)
527 and then Present (Effective_Extra_Accessibility (Entity (N)))
529 Param_Ent := Entity (N);
530 while Present (Renamed_Object (Param_Ent)) loop
532 -- Renamed_Object must return an Entity_Name here
533 -- because of preceding "Present (E_E_A (...))" test.
535 Param_Ent := Entity (Renamed_Object (Param_Ent));
539 if Inside_A_Generic then
542 -- Only apply the run-time check if the access parameter has an
543 -- associated extra access level parameter and when the level of the
544 -- type is less deep than the level of the access parameter, and
545 -- accessibility checks are not suppressed.
547 elsif Present (Param_Ent)
548 and then Present (Extra_Accessibility (Param_Ent))
549 and then UI_Gt (Object_Access_Level (N),
550 Deepest_Type_Access_Level (Typ))
551 and then not Accessibility_Checks_Suppressed (Param_Ent)
552 and then not Accessibility_Checks_Suppressed (Typ)
555 New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc);
558 Make_Integer_Literal (Loc, Deepest_Type_Access_Level (Typ));
560 -- Raise Program_Error if the accessibility level of the access
561 -- parameter is deeper than the level of the target access type.
563 Insert_Action (Insert_Node,
564 Make_Raise_Program_Error (Loc,
567 Left_Opnd => Param_Level,
568 Right_Opnd => Type_Level),
569 Reason => PE_Accessibility_Check_Failed));
571 Analyze_And_Resolve (N);
573 end Apply_Accessibility_Check;
575 --------------------------------
576 -- Apply_Address_Clause_Check --
577 --------------------------------
579 procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is
580 pragma Assert (Nkind (N) = N_Freeze_Entity);
582 AC : constant Node_Id := Address_Clause (E);
583 Loc : constant Source_Ptr := Sloc (AC);
584 Typ : constant Entity_Id := Etype (E);
585 Aexp : constant Node_Id := Expression (AC);
588 -- Address expression (not necessarily the same as Aexp, for example
589 -- when Aexp is a reference to a constant, in which case Expr gets
590 -- reset to reference the value expression of the constant.
592 procedure Compile_Time_Bad_Alignment;
593 -- Post error warnings when alignment is known to be incompatible. Note
594 -- that we do not go as far as inserting a raise of Program_Error since
595 -- this is an erroneous case, and it may happen that we are lucky and an
596 -- underaligned address turns out to be OK after all.
598 --------------------------------
599 -- Compile_Time_Bad_Alignment --
600 --------------------------------
602 procedure Compile_Time_Bad_Alignment is
604 if Address_Clause_Overlay_Warnings then
606 ("?o?specified address for& may be inconsistent with alignment",
609 ("\?o?program execution may be erroneous (RM 13.3(27))",
611 Set_Address_Warning_Posted (AC);
613 end Compile_Time_Bad_Alignment;
615 -- Start of processing for Apply_Address_Clause_Check
618 -- See if alignment check needed. Note that we never need a check if the
619 -- maximum alignment is one, since the check will always succeed.
621 -- Note: we do not check for checks suppressed here, since that check
622 -- was done in Sem_Ch13 when the address clause was processed. We are
623 -- only called if checks were not suppressed. The reason for this is
624 -- that we have to delay the call to Apply_Alignment_Check till freeze
625 -- time (so that all types etc are elaborated), but we have to check
626 -- the status of check suppressing at the point of the address clause.
629 or else not Check_Address_Alignment (AC)
630 or else Maximum_Alignment = 1
635 -- Obtain expression from address clause
637 Expr := Expression (AC);
639 -- The following loop digs for the real expression to use in the check
642 -- For constant, get constant expression
644 if Is_Entity_Name (Expr)
645 and then Ekind (Entity (Expr)) = E_Constant
647 Expr := Constant_Value (Entity (Expr));
649 -- For unchecked conversion, get result to convert
651 elsif Nkind (Expr) = N_Unchecked_Type_Conversion then
652 Expr := Expression (Expr);
654 -- For (common case) of To_Address call, get argument
656 elsif Nkind (Expr) = N_Function_Call
657 and then Is_Entity_Name (Name (Expr))
658 and then Is_RTE (Entity (Name (Expr)), RE_To_Address)
660 Expr := First (Parameter_Associations (Expr));
662 if Nkind (Expr) = N_Parameter_Association then
663 Expr := Explicit_Actual_Parameter (Expr);
666 -- We finally have the real expression
673 -- See if we know that Expr has a bad alignment at compile time
675 if Compile_Time_Known_Value (Expr)
676 and then (Known_Alignment (E) or else Known_Alignment (Typ))
679 AL : Uint := Alignment (Typ);
682 -- The object alignment might be more restrictive than the
685 if Known_Alignment (E) then
689 if Expr_Value (Expr) mod AL /= 0 then
690 Compile_Time_Bad_Alignment;
696 -- If the expression has the form X'Address, then we can find out if
697 -- the object X has an alignment that is compatible with the object E.
698 -- If it hasn't or we don't know, we defer issuing the warning until
699 -- the end of the compilation to take into account back end annotations.
701 elsif Nkind (Expr) = N_Attribute_Reference
702 and then Attribute_Name (Expr) = Name_Address
703 and then Has_Compatible_Alignment (E, Prefix (Expr)) = Known_Compatible
708 -- Here we do not know if the value is acceptable. Strictly we don't
709 -- have to do anything, since if the alignment is bad, we have an
710 -- erroneous program. However we are allowed to check for erroneous
711 -- conditions and we decide to do this by default if the check is not
714 -- However, don't do the check if elaboration code is unwanted
716 if Restriction_Active (No_Elaboration_Code) then
719 -- Generate a check to raise PE if alignment may be inappropriate
722 -- If the original expression is a non-static constant, use the
723 -- name of the constant itself rather than duplicating its
724 -- defining expression, which was extracted above.
726 -- Note: Expr is empty if the address-clause is applied to in-mode
727 -- actuals (allowed by 13.1(22)).
729 if not Present (Expr)
731 (Is_Entity_Name (Expression (AC))
732 and then Ekind (Entity (Expression (AC))) = E_Constant
733 and then Nkind (Parent (Entity (Expression (AC))))
734 = N_Object_Declaration)
736 Expr := New_Copy_Tree (Expression (AC));
738 Remove_Side_Effects (Expr);
741 if No (Actions (N)) then
742 Set_Actions (N, New_List);
745 Prepend_To (Actions (N),
746 Make_Raise_Program_Error (Loc,
753 (RTE (RE_Integer_Address), Expr),
755 Make_Attribute_Reference (Loc,
756 Prefix => New_Occurrence_Of (E, Loc),
757 Attribute_Name => Name_Alignment)),
758 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
759 Reason => PE_Misaligned_Address_Value));
760 Analyze (First (Actions (N)), Suppress => All_Checks);
762 -- If the address clause generates an alignment check and we are
763 -- in ZPF or some restricted run-time, add a warning to explain
764 -- the propagation warning that is generated by the check.
766 if Nkind (First (Actions (N))) = N_Raise_Program_Error
767 and then not Warnings_Off (E)
768 and then Restriction_Active (No_Exception_Propagation)
771 ("address value may be incompatible with alignment of object?",
779 -- If we have some missing run time component in configurable run time
780 -- mode then just skip the check (it is not required in any case).
782 when RE_Not_Available =>
784 end Apply_Address_Clause_Check;
786 -------------------------------------
787 -- Apply_Arithmetic_Overflow_Check --
788 -------------------------------------
790 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
792 -- Use old routine in almost all cases (the only case we are treating
793 -- specially is the case of a signed integer arithmetic op with the
794 -- overflow checking mode set to MINIMIZED or ELIMINATED).
796 if Overflow_Check_Mode = Strict
797 or else not Is_Signed_Integer_Arithmetic_Op (N)
799 Apply_Arithmetic_Overflow_Strict (N);
801 -- Otherwise use the new routine for the case of a signed integer
802 -- arithmetic op, with Do_Overflow_Check set to True, and the checking
803 -- mode is MINIMIZED or ELIMINATED.
806 Apply_Arithmetic_Overflow_Minimized_Eliminated (N);
808 end Apply_Arithmetic_Overflow_Check;
810 --------------------------------------
811 -- Apply_Arithmetic_Overflow_Strict --
812 --------------------------------------
814 -- This routine is called only if the type is an integer type, and a
815 -- software arithmetic overflow check may be needed for op (add, subtract,
816 -- or multiply). This check is performed only if Software_Overflow_Checking
817 -- is enabled and Do_Overflow_Check is set. In this case we expand the
818 -- operation into a more complex sequence of tests that ensures that
819 -- overflow is properly caught.
821 -- This is used in CHECKED modes. It is identical to the code for this
822 -- cases before the big overflow earthquake, thus ensuring that in this
823 -- modes we have compatible behavior (and reliability) to what was there
824 -- before. It is also called for types other than signed integers, and if
825 -- the Do_Overflow_Check flag is off.
827 -- Note: we also call this routine if we decide in the MINIMIZED case
828 -- to give up and just generate an overflow check without any fuss.
830 procedure Apply_Arithmetic_Overflow_Strict (N : Node_Id) is
831 Loc : constant Source_Ptr := Sloc (N);
832 Typ : constant Entity_Id := Etype (N);
833 Rtyp : constant Entity_Id := Root_Type (Typ);
836 -- Nothing to do if Do_Overflow_Check not set or overflow checks
839 if not Do_Overflow_Check (N) then
843 -- An interesting special case. If the arithmetic operation appears as
844 -- the operand of a type conversion:
848 -- and all the following conditions apply:
850 -- arithmetic operation is for a signed integer type
851 -- target type type1 is a static integer subtype
852 -- range of x and y are both included in the range of type1
853 -- range of x op y is included in the range of type1
854 -- size of type1 is at least twice the result size of op
856 -- then we don't do an overflow check in any case, instead we transform
857 -- the operation so that we end up with:
859 -- type1 (type1 (x) op type1 (y))
861 -- This avoids intermediate overflow before the conversion. It is
862 -- explicitly permitted by RM 3.5.4(24):
864 -- For the execution of a predefined operation of a signed integer
865 -- type, the implementation need not raise Constraint_Error if the
866 -- result is outside the base range of the type, so long as the
867 -- correct result is produced.
869 -- It's hard to imagine that any programmer counts on the exception
870 -- being raised in this case, and in any case it's wrong coding to
871 -- have this expectation, given the RM permission. Furthermore, other
872 -- Ada compilers do allow such out of range results.
874 -- Note that we do this transformation even if overflow checking is
875 -- off, since this is precisely about giving the "right" result and
876 -- avoiding the need for an overflow check.
878 -- Note: this circuit is partially redundant with respect to the similar
879 -- processing in Exp_Ch4.Expand_N_Type_Conversion, but the latter deals
880 -- with cases that do not come through here. We still need the following
881 -- processing even with the Exp_Ch4 code in place, since we want to be
882 -- sure not to generate the arithmetic overflow check in these cases
883 -- (Exp_Ch4 would have a hard time removing them once generated).
885 if Is_Signed_Integer_Type (Typ)
886 and then Nkind (Parent (N)) = N_Type_Conversion
888 Conversion_Optimization : declare
889 Target_Type : constant Entity_Id :=
890 Base_Type (Entity (Subtype_Mark (Parent (N))));
904 if Is_Integer_Type (Target_Type)
905 and then RM_Size (Root_Type (Target_Type)) >= 2 * RM_Size (Rtyp)
907 Tlo := Expr_Value (Type_Low_Bound (Target_Type));
908 Thi := Expr_Value (Type_High_Bound (Target_Type));
911 (Left_Opnd (N), LOK, Llo, Lhi, Assume_Valid => True);
913 (Right_Opnd (N), ROK, Rlo, Rhi, Assume_Valid => True);
916 and then Tlo <= Llo and then Lhi <= Thi
917 and then Tlo <= Rlo and then Rhi <= Thi
919 Determine_Range (N, VOK, Vlo, Vhi, Assume_Valid => True);
921 if VOK and then Tlo <= Vlo and then Vhi <= Thi then
922 Rewrite (Left_Opnd (N),
923 Make_Type_Conversion (Loc,
924 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
925 Expression => Relocate_Node (Left_Opnd (N))));
927 Rewrite (Right_Opnd (N),
928 Make_Type_Conversion (Loc,
929 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
930 Expression => Relocate_Node (Right_Opnd (N))));
932 -- Rewrite the conversion operand so that the original
933 -- node is retained, in order to avoid the warning for
934 -- redundant conversions in Resolve_Type_Conversion.
936 Rewrite (N, Relocate_Node (N));
938 Set_Etype (N, Target_Type);
940 Analyze_And_Resolve (Left_Opnd (N), Target_Type);
941 Analyze_And_Resolve (Right_Opnd (N), Target_Type);
943 -- Given that the target type is twice the size of the
944 -- source type, overflow is now impossible, so we can
945 -- safely kill the overflow check and return.
947 Set_Do_Overflow_Check (N, False);
952 end Conversion_Optimization;
955 -- Now see if an overflow check is required
958 Siz : constant Int := UI_To_Int (Esize (Rtyp));
959 Dsiz : constant Int := Siz * 2;
966 -- Skip check if back end does overflow checks, or the overflow flag
967 -- is not set anyway, or we are not doing code expansion, or the
968 -- parent node is a type conversion whose operand is an arithmetic
969 -- operation on signed integers on which the expander can promote
970 -- later the operands to type Integer (see Expand_N_Type_Conversion).
972 -- Special case CLI target, where arithmetic overflow checks can be
973 -- performed for integer and long_integer
975 if Backend_Overflow_Checks_On_Target
976 or else not Do_Overflow_Check (N)
977 or else not Expander_Active
978 or else (Present (Parent (N))
979 and then Nkind (Parent (N)) = N_Type_Conversion
980 and then Integer_Promotion_Possible (Parent (N)))
982 (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
987 -- Otherwise, generate the full general code for front end overflow
988 -- detection, which works by doing arithmetic in a larger type:
994 -- Typ (Checktyp (x) op Checktyp (y));
996 -- where Typ is the type of the original expression, and Checktyp is
997 -- an integer type of sufficient length to hold the largest possible
1000 -- If the size of check type exceeds the size of Long_Long_Integer,
1001 -- we use a different approach, expanding to:
1003 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
1005 -- where xxx is Add, Multiply or Subtract as appropriate
1007 -- Find check type if one exists
1009 if Dsiz <= Standard_Integer_Size then
1010 Ctyp := Standard_Integer;
1012 elsif Dsiz <= Standard_Long_Long_Integer_Size then
1013 Ctyp := Standard_Long_Long_Integer;
1015 -- No check type exists, use runtime call
1018 if Nkind (N) = N_Op_Add then
1019 Cent := RE_Add_With_Ovflo_Check;
1021 elsif Nkind (N) = N_Op_Multiply then
1022 Cent := RE_Multiply_With_Ovflo_Check;
1025 pragma Assert (Nkind (N) = N_Op_Subtract);
1026 Cent := RE_Subtract_With_Ovflo_Check;
1031 Make_Function_Call (Loc,
1032 Name => New_Reference_To (RTE (Cent), Loc),
1033 Parameter_Associations => New_List (
1034 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
1035 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
1037 Analyze_And_Resolve (N, Typ);
1041 -- If we fall through, we have the case where we do the arithmetic
1042 -- in the next higher type and get the check by conversion. In these
1043 -- cases Ctyp is set to the type to be used as the check type.
1045 Opnod := Relocate_Node (N);
1047 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
1050 Set_Etype (Opnd, Ctyp);
1051 Set_Analyzed (Opnd, True);
1052 Set_Left_Opnd (Opnod, Opnd);
1054 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
1057 Set_Etype (Opnd, Ctyp);
1058 Set_Analyzed (Opnd, True);
1059 Set_Right_Opnd (Opnod, Opnd);
1061 -- The type of the operation changes to the base type of the check
1062 -- type, and we reset the overflow check indication, since clearly no
1063 -- overflow is possible now that we are using a double length type.
1064 -- We also set the Analyzed flag to avoid a recursive attempt to
1067 Set_Etype (Opnod, Base_Type (Ctyp));
1068 Set_Do_Overflow_Check (Opnod, False);
1069 Set_Analyzed (Opnod, True);
1071 -- Now build the outer conversion
1073 Opnd := OK_Convert_To (Typ, Opnod);
1075 Set_Etype (Opnd, Typ);
1077 -- In the discrete type case, we directly generate the range check
1078 -- for the outer operand. This range check will implement the
1079 -- required overflow check.
1081 if Is_Discrete_Type (Typ) then
1083 Generate_Range_Check
1084 (Expression (N), Typ, CE_Overflow_Check_Failed);
1086 -- For other types, we enable overflow checking on the conversion,
1087 -- after setting the node as analyzed to prevent recursive attempts
1088 -- to expand the conversion node.
1091 Set_Analyzed (Opnd, True);
1092 Enable_Overflow_Check (Opnd);
1097 when RE_Not_Available =>
1100 end Apply_Arithmetic_Overflow_Strict;
1102 ----------------------------------------------------
1103 -- Apply_Arithmetic_Overflow_Minimized_Eliminated --
1104 ----------------------------------------------------
1106 procedure Apply_Arithmetic_Overflow_Minimized_Eliminated (Op : Node_Id) is
1107 pragma Assert (Is_Signed_Integer_Arithmetic_Op (Op));
1109 Loc : constant Source_Ptr := Sloc (Op);
1110 P : constant Node_Id := Parent (Op);
1112 LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer);
1113 -- Operands and results are of this type when we convert
1115 Result_Type : constant Entity_Id := Etype (Op);
1116 -- Original result type
1118 Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
1119 pragma Assert (Check_Mode in Minimized_Or_Eliminated);
1122 -- Ranges of values for result
1125 -- Nothing to do if our parent is one of the following:
1127 -- Another signed integer arithmetic op
1128 -- A membership operation
1129 -- A comparison operation
1131 -- In all these cases, we will process at the higher level (and then
1132 -- this node will be processed during the downwards recursion that
1133 -- is part of the processing in Minimize_Eliminate_Overflows).
1135 if Is_Signed_Integer_Arithmetic_Op (P)
1136 or else Nkind (P) in N_Membership_Test
1137 or else Nkind (P) in N_Op_Compare
1139 -- This is also true for an alternative in a case expression
1141 or else Nkind (P) = N_Case_Expression_Alternative
1143 -- This is also true for a range operand in a membership test
1145 or else (Nkind (P) = N_Range
1146 and then Nkind (Parent (P)) in N_Membership_Test)
1151 -- Otherwise, we have a top level arithmetic operation node, and this
1152 -- is where we commence the special processing for MINIMIZED/ELIMINATED
1153 -- modes. This is the case where we tell the machinery not to move into
1154 -- Bignum mode at this top level (of course the top level operation
1155 -- will still be in Bignum mode if either of its operands are of type
1158 Minimize_Eliminate_Overflows (Op, Lo, Hi, Top_Level => True);
1160 -- That call may but does not necessarily change the result type of Op.
1161 -- It is the job of this routine to undo such changes, so that at the
1162 -- top level, we have the proper type. This "undoing" is a point at
1163 -- which a final overflow check may be applied.
1165 -- If the result type was not fiddled we are all set. We go to base
1166 -- types here because things may have been rewritten to generate the
1167 -- base type of the operand types.
1169 if Base_Type (Etype (Op)) = Base_Type (Result_Type) then
1174 elsif Is_RTE (Etype (Op), RE_Bignum) then
1176 -- We need a sequence that looks like:
1178 -- Rnn : Result_Type;
1181 -- M : Mark_Id := SS_Mark;
1183 -- Rnn := Long_Long_Integer'Base (From_Bignum (Op));
1187 -- This block is inserted (using Insert_Actions), and then the node
1188 -- is replaced with a reference to Rnn.
1190 -- A special case arises if our parent is a conversion node. In this
1191 -- case no point in generating a conversion to Result_Type, we will
1192 -- let the parent handle this. Note that this special case is not
1193 -- just about optimization. Consider
1197 -- X := Long_Long_Integer'Base (A * (B ** C));
1199 -- Now the product may fit in Long_Long_Integer but not in Integer.
1200 -- In MINIMIZED/ELIMINATED mode, we don't want to introduce an
1201 -- overflow exception for this intermediate value.
1204 Blk : constant Node_Id := Make_Bignum_Block (Loc);
1205 Rnn : constant Entity_Id := Make_Temporary (Loc, 'R', Op);
1211 RHS := Convert_From_Bignum (Op);
1213 if Nkind (P) /= N_Type_Conversion then
1214 Convert_To_And_Rewrite (Result_Type, RHS);
1215 Rtype := Result_Type;
1217 -- Interesting question, do we need a check on that conversion
1218 -- operation. Answer, not if we know the result is in range.
1219 -- At the moment we are not taking advantage of this. To be
1220 -- looked at later ???
1227 (First (Statements (Handled_Statement_Sequence (Blk))),
1228 Make_Assignment_Statement (Loc,
1229 Name => New_Occurrence_Of (Rnn, Loc),
1230 Expression => RHS));
1232 Insert_Actions (Op, New_List (
1233 Make_Object_Declaration (Loc,
1234 Defining_Identifier => Rnn,
1235 Object_Definition => New_Occurrence_Of (Rtype, Loc)),
1238 Rewrite (Op, New_Occurrence_Of (Rnn, Loc));
1239 Analyze_And_Resolve (Op);
1242 -- Here we know the result is Long_Long_Integer'Base, of that it has
1243 -- been rewritten because the parent operation is a conversion. See
1244 -- Apply_Arithmetic_Overflow_Strict.Conversion_Optimization.
1248 (Etype (Op) = LLIB or else Nkind (Parent (Op)) = N_Type_Conversion);
1250 -- All we need to do here is to convert the result to the proper
1251 -- result type. As explained above for the Bignum case, we can
1252 -- omit this if our parent is a type conversion.
1254 if Nkind (P) /= N_Type_Conversion then
1255 Convert_To_And_Rewrite (Result_Type, Op);
1258 Analyze_And_Resolve (Op);
1260 end Apply_Arithmetic_Overflow_Minimized_Eliminated;
1262 ----------------------------
1263 -- Apply_Constraint_Check --
1264 ----------------------------
1266 procedure Apply_Constraint_Check
1269 No_Sliding : Boolean := False)
1271 Desig_Typ : Entity_Id;
1274 -- No checks inside a generic (check the instantiations)
1276 if Inside_A_Generic then
1280 -- Apply required constraint checks
1282 if Is_Scalar_Type (Typ) then
1283 Apply_Scalar_Range_Check (N, Typ);
1285 elsif Is_Array_Type (Typ) then
1287 -- A useful optimization: an aggregate with only an others clause
1288 -- always has the right bounds.
1290 if Nkind (N) = N_Aggregate
1291 and then No (Expressions (N))
1293 (First (Choices (First (Component_Associations (N)))))
1299 if Is_Constrained (Typ) then
1300 Apply_Length_Check (N, Typ);
1303 Apply_Range_Check (N, Typ);
1306 Apply_Range_Check (N, Typ);
1309 elsif (Is_Record_Type (Typ) or else Is_Private_Type (Typ))
1310 and then Has_Discriminants (Base_Type (Typ))
1311 and then Is_Constrained (Typ)
1313 Apply_Discriminant_Check (N, Typ);
1315 elsif Is_Access_Type (Typ) then
1317 Desig_Typ := Designated_Type (Typ);
1319 -- No checks necessary if expression statically null
1321 if Known_Null (N) then
1322 if Can_Never_Be_Null (Typ) then
1323 Install_Null_Excluding_Check (N);
1326 -- No sliding possible on access to arrays
1328 elsif Is_Array_Type (Desig_Typ) then
1329 if Is_Constrained (Desig_Typ) then
1330 Apply_Length_Check (N, Typ);
1333 Apply_Range_Check (N, Typ);
1335 elsif Has_Discriminants (Base_Type (Desig_Typ))
1336 and then Is_Constrained (Desig_Typ)
1338 Apply_Discriminant_Check (N, Typ);
1341 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1342 -- this check if the constraint node is illegal, as shown by having
1343 -- an error posted. This additional guard prevents cascaded errors
1344 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1346 if Can_Never_Be_Null (Typ)
1347 and then not Can_Never_Be_Null (Etype (N))
1348 and then not Error_Posted (N)
1350 Install_Null_Excluding_Check (N);
1353 end Apply_Constraint_Check;
1355 ------------------------------
1356 -- Apply_Discriminant_Check --
1357 ------------------------------
1359 procedure Apply_Discriminant_Check
1362 Lhs : Node_Id := Empty)
1364 Loc : constant Source_Ptr := Sloc (N);
1365 Do_Access : constant Boolean := Is_Access_Type (Typ);
1366 S_Typ : Entity_Id := Etype (N);
1370 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean;
1371 -- A heap object with an indefinite subtype is constrained by its
1372 -- initial value, and assigning to it requires a constraint_check.
1373 -- The target may be an explicit dereference, or a renaming of one.
1375 function Is_Aliased_Unconstrained_Component return Boolean;
1376 -- It is possible for an aliased component to have a nominal
1377 -- unconstrained subtype (through instantiation). If this is a
1378 -- discriminated component assigned in the expansion of an aggregate
1379 -- in an initialization, the check must be suppressed. This unusual
1380 -- situation requires a predicate of its own.
1382 ----------------------------------
1383 -- Denotes_Explicit_Dereference --
1384 ----------------------------------
1386 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean is
1389 Nkind (Obj) = N_Explicit_Dereference
1391 (Is_Entity_Name (Obj)
1392 and then Present (Renamed_Object (Entity (Obj)))
1393 and then Nkind (Renamed_Object (Entity (Obj))) =
1394 N_Explicit_Dereference);
1395 end Denotes_Explicit_Dereference;
1397 ----------------------------------------
1398 -- Is_Aliased_Unconstrained_Component --
1399 ----------------------------------------
1401 function Is_Aliased_Unconstrained_Component return Boolean is
1406 if Nkind (Lhs) /= N_Selected_Component then
1409 Comp := Entity (Selector_Name (Lhs));
1410 Pref := Prefix (Lhs);
1413 if Ekind (Comp) /= E_Component
1414 or else not Is_Aliased (Comp)
1419 return not Comes_From_Source (Pref)
1420 and then In_Instance
1421 and then not Is_Constrained (Etype (Comp));
1422 end Is_Aliased_Unconstrained_Component;
1424 -- Start of processing for Apply_Discriminant_Check
1428 T_Typ := Designated_Type (Typ);
1433 -- Nothing to do if discriminant checks are suppressed or else no code
1434 -- is to be generated
1436 if not Expander_Active
1437 or else Discriminant_Checks_Suppressed (T_Typ)
1442 -- No discriminant checks necessary for an access when expression is
1443 -- statically Null. This is not only an optimization, it is fundamental
1444 -- because otherwise discriminant checks may be generated in init procs
1445 -- for types containing an access to a not-yet-frozen record, causing a
1446 -- deadly forward reference.
1448 -- Also, if the expression is of an access type whose designated type is
1449 -- incomplete, then the access value must be null and we suppress the
1452 if Known_Null (N) then
1455 elsif Is_Access_Type (S_Typ) then
1456 S_Typ := Designated_Type (S_Typ);
1458 if Ekind (S_Typ) = E_Incomplete_Type then
1463 -- If an assignment target is present, then we need to generate the
1464 -- actual subtype if the target is a parameter or aliased object with
1465 -- an unconstrained nominal subtype.
1467 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1468 -- subtype to the parameter and dereference cases, since other aliased
1469 -- objects are unconstrained (unless the nominal subtype is explicitly
1473 and then (Present (Param_Entity (Lhs))
1474 or else (Ada_Version < Ada_2005
1475 and then not Is_Constrained (T_Typ)
1476 and then Is_Aliased_View (Lhs)
1477 and then not Is_Aliased_Unconstrained_Component)
1478 or else (Ada_Version >= Ada_2005
1479 and then not Is_Constrained (T_Typ)
1480 and then Denotes_Explicit_Dereference (Lhs)
1481 and then Nkind (Original_Node (Lhs)) /=
1484 T_Typ := Get_Actual_Subtype (Lhs);
1487 -- Nothing to do if the type is unconstrained (this is the case where
1488 -- the actual subtype in the RM sense of N is unconstrained and no check
1491 if not Is_Constrained (T_Typ) then
1494 -- Ada 2005: nothing to do if the type is one for which there is a
1495 -- partial view that is constrained.
1497 elsif Ada_Version >= Ada_2005
1498 and then Object_Type_Has_Constrained_Partial_View
1499 (Typ => Base_Type (T_Typ),
1500 Scop => Current_Scope)
1505 -- Nothing to do if the type is an Unchecked_Union
1507 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1511 -- Suppress checks if the subtypes are the same. the check must be
1512 -- preserved in an assignment to a formal, because the constraint is
1513 -- given by the actual.
1515 if Nkind (Original_Node (N)) /= N_Allocator
1517 or else not Is_Entity_Name (Lhs)
1518 or else No (Param_Entity (Lhs)))
1521 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1522 and then not Is_Aliased_View (Lhs)
1527 -- We can also eliminate checks on allocators with a subtype mark that
1528 -- coincides with the context type. The context type may be a subtype
1529 -- without a constraint (common case, a generic actual).
1531 elsif Nkind (Original_Node (N)) = N_Allocator
1532 and then Is_Entity_Name (Expression (Original_Node (N)))
1535 Alloc_Typ : constant Entity_Id :=
1536 Entity (Expression (Original_Node (N)));
1539 if Alloc_Typ = T_Typ
1540 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1541 and then Is_Entity_Name (
1542 Subtype_Indication (Parent (T_Typ)))
1543 and then Alloc_Typ = Base_Type (T_Typ))
1551 -- See if we have a case where the types are both constrained, and all
1552 -- the constraints are constants. In this case, we can do the check
1553 -- successfully at compile time.
1555 -- We skip this check for the case where the node is rewritten`as
1556 -- an allocator, because it already carries the context subtype,
1557 -- and extracting the discriminants from the aggregate is messy.
1559 if Is_Constrained (S_Typ)
1560 and then Nkind (Original_Node (N)) /= N_Allocator
1570 -- S_Typ may not have discriminants in the case where it is a
1571 -- private type completed by a default discriminated type. In that
1572 -- case, we need to get the constraints from the underlying_type.
1573 -- If the underlying type is unconstrained (i.e. has no default
1574 -- discriminants) no check is needed.
1576 if Has_Discriminants (S_Typ) then
1577 Discr := First_Discriminant (S_Typ);
1578 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1581 Discr := First_Discriminant (Underlying_Type (S_Typ));
1584 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1590 -- A further optimization: if T_Typ is derived from S_Typ
1591 -- without imposing a constraint, no check is needed.
1593 if Nkind (Original_Node (Parent (T_Typ))) =
1594 N_Full_Type_Declaration
1597 Type_Def : constant Node_Id :=
1598 Type_Definition (Original_Node (Parent (T_Typ)));
1600 if Nkind (Type_Def) = N_Derived_Type_Definition
1601 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1602 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1610 -- Constraint may appear in full view of type
1612 if Ekind (T_Typ) = E_Private_Subtype
1613 and then Present (Full_View (T_Typ))
1616 First_Elmt (Discriminant_Constraint (Full_View (T_Typ)));
1619 First_Elmt (Discriminant_Constraint (T_Typ));
1622 while Present (Discr) loop
1623 ItemS := Node (DconS);
1624 ItemT := Node (DconT);
1626 -- For a discriminated component type constrained by the
1627 -- current instance of an enclosing type, there is no
1628 -- applicable discriminant check.
1630 if Nkind (ItemT) = N_Attribute_Reference
1631 and then Is_Access_Type (Etype (ItemT))
1632 and then Is_Entity_Name (Prefix (ItemT))
1633 and then Is_Type (Entity (Prefix (ItemT)))
1638 -- If the expressions for the discriminants are identical
1639 -- and it is side-effect free (for now just an entity),
1640 -- this may be a shared constraint, e.g. from a subtype
1641 -- without a constraint introduced as a generic actual.
1642 -- Examine other discriminants if any.
1645 and then Is_Entity_Name (ItemS)
1649 elsif not Is_OK_Static_Expression (ItemS)
1650 or else not Is_OK_Static_Expression (ItemT)
1654 elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
1655 if Do_Access then -- needs run-time check.
1658 Apply_Compile_Time_Constraint_Error
1659 (N, "incorrect value for discriminant&??",
1660 CE_Discriminant_Check_Failed, Ent => Discr);
1667 Next_Discriminant (Discr);
1676 -- Here we need a discriminant check. First build the expression
1677 -- for the comparisons of the discriminants:
1679 -- (n.disc1 /= typ.disc1) or else
1680 -- (n.disc2 /= typ.disc2) or else
1682 -- (n.discn /= typ.discn)
1684 Cond := Build_Discriminant_Checks (N, T_Typ);
1686 -- If Lhs is set and is a parameter, then the condition is guarded by:
1687 -- lhs'constrained and then (condition built above)
1689 if Present (Param_Entity (Lhs)) then
1693 Make_Attribute_Reference (Loc,
1694 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1695 Attribute_Name => Name_Constrained),
1696 Right_Opnd => Cond);
1700 Cond := Guard_Access (Cond, Loc, N);
1704 Make_Raise_Constraint_Error (Loc,
1706 Reason => CE_Discriminant_Check_Failed));
1707 end Apply_Discriminant_Check;
1709 -------------------------
1710 -- Apply_Divide_Checks --
1711 -------------------------
1713 procedure Apply_Divide_Checks (N : Node_Id) is
1714 Loc : constant Source_Ptr := Sloc (N);
1715 Typ : constant Entity_Id := Etype (N);
1716 Left : constant Node_Id := Left_Opnd (N);
1717 Right : constant Node_Id := Right_Opnd (N);
1719 Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
1720 -- Current overflow checking mode
1730 pragma Warnings (Off, Lhi);
1731 -- Don't actually use this value
1734 -- If we are operating in MINIMIZED or ELIMINATED mode, and we are
1735 -- operating on signed integer types, then the only thing this routine
1736 -- does is to call Apply_Arithmetic_Overflow_Minimized_Eliminated. That
1737 -- procedure will (possibly later on during recursive downward calls),
1738 -- ensure that any needed overflow/division checks are properly applied.
1740 if Mode in Minimized_Or_Eliminated
1741 and then Is_Signed_Integer_Type (Typ)
1743 Apply_Arithmetic_Overflow_Minimized_Eliminated (N);
1747 -- Proceed here in SUPPRESSED or CHECKED modes
1750 and then not Backend_Divide_Checks_On_Target
1751 and then Check_Needed (Right, Division_Check)
1753 Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True);
1755 -- Deal with division check
1757 if Do_Division_Check (N)
1758 and then not Division_Checks_Suppressed (Typ)
1760 Apply_Division_Check (N, Rlo, Rhi, ROK);
1763 -- Deal with overflow check
1765 if Do_Overflow_Check (N)
1766 and then not Overflow_Checks_Suppressed (Etype (N))
1769 -- Test for extremely annoying case of xxx'First divided by -1
1770 -- for division of signed integer types (only overflow case).
1772 if Nkind (N) = N_Op_Divide
1773 and then Is_Signed_Integer_Type (Typ)
1775 Determine_Range (Left, LOK, Llo, Lhi, Assume_Valid => True);
1776 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1778 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1780 ((not LOK) or else (Llo = LLB))
1783 Make_Raise_Constraint_Error (Loc,
1789 Duplicate_Subexpr_Move_Checks (Left),
1790 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1794 Left_Opnd => Duplicate_Subexpr (Right),
1795 Right_Opnd => Make_Integer_Literal (Loc, -1))),
1797 Reason => CE_Overflow_Check_Failed));
1802 end Apply_Divide_Checks;
1804 --------------------------
1805 -- Apply_Division_Check --
1806 --------------------------
1808 procedure Apply_Division_Check
1814 pragma Assert (Do_Division_Check (N));
1816 Loc : constant Source_Ptr := Sloc (N);
1817 Right : constant Node_Id := Right_Opnd (N);
1821 and then not Backend_Divide_Checks_On_Target
1822 and then Check_Needed (Right, Division_Check)
1824 -- See if division by zero possible, and if so generate test. This
1825 -- part of the test is not controlled by the -gnato switch, since
1826 -- it is a Division_Check and not an Overflow_Check.
1828 if Do_Division_Check (N) then
1829 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1831 Make_Raise_Constraint_Error (Loc,
1834 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1835 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1836 Reason => CE_Divide_By_Zero));
1840 end Apply_Division_Check;
1842 ----------------------------------
1843 -- Apply_Float_Conversion_Check --
1844 ----------------------------------
1846 -- Let F and I be the source and target types of the conversion. The RM
1847 -- specifies that a floating-point value X is rounded to the nearest
1848 -- integer, with halfway cases being rounded away from zero. The rounded
1849 -- value of X is checked against I'Range.
1851 -- The catch in the above paragraph is that there is no good way to know
1852 -- whether the round-to-integer operation resulted in overflow. A remedy is
1853 -- to perform a range check in the floating-point domain instead, however:
1855 -- (1) The bounds may not be known at compile time
1856 -- (2) The check must take into account rounding or truncation.
1857 -- (3) The range of type I may not be exactly representable in F.
1858 -- (4) For the rounding case, The end-points I'First - 0.5 and
1859 -- I'Last + 0.5 may or may not be in range, depending on the
1860 -- sign of I'First and I'Last.
1861 -- (5) X may be a NaN, which will fail any comparison
1863 -- The following steps correctly convert X with rounding:
1865 -- (1) If either I'First or I'Last is not known at compile time, use
1866 -- I'Base instead of I in the next three steps and perform a
1867 -- regular range check against I'Range after conversion.
1868 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1869 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1870 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1871 -- In other words, take one of the closest floating-point numbers
1872 -- (which is an integer value) to I'First, and see if it is in
1874 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1875 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1876 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1877 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1878 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1880 -- For the truncating case, replace steps (2) and (3) as follows:
1881 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1882 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1884 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1885 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1888 procedure Apply_Float_Conversion_Check
1890 Target_Typ : Entity_Id)
1892 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1893 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1894 Loc : constant Source_Ptr := Sloc (Ck_Node);
1895 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1896 Target_Base : constant Entity_Id :=
1897 Implementation_Base_Type (Target_Typ);
1899 Par : constant Node_Id := Parent (Ck_Node);
1900 pragma Assert (Nkind (Par) = N_Type_Conversion);
1901 -- Parent of check node, must be a type conversion
1903 Truncate : constant Boolean := Float_Truncate (Par);
1904 Max_Bound : constant Uint :=
1906 (Machine_Radix_Value (Expr_Type),
1907 Machine_Mantissa_Value (Expr_Type) - 1) - 1;
1909 -- Largest bound, so bound plus or minus half is a machine number of F
1911 Ifirst, Ilast : Uint;
1912 -- Bounds of integer type
1915 -- Bounds to check in floating-point domain
1917 Lo_OK, Hi_OK : Boolean;
1918 -- True iff Lo resp. Hi belongs to I'Range
1920 Lo_Chk, Hi_Chk : Node_Id;
1921 -- Expressions that are False iff check fails
1923 Reason : RT_Exception_Code;
1926 -- We do not need checks if we are not generating code (i.e. the full
1927 -- expander is not active). In SPARK mode, we specifically don't want
1928 -- the frontend to expand these checks, which are dealt with directly
1929 -- in the formal verification backend.
1931 if not Expander_Active then
1935 if not Compile_Time_Known_Value (LB)
1936 or not Compile_Time_Known_Value (HB)
1939 -- First check that the value falls in the range of the base type,
1940 -- to prevent overflow during conversion and then perform a
1941 -- regular range check against the (dynamic) bounds.
1943 pragma Assert (Target_Base /= Target_Typ);
1945 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Par);
1948 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1949 Set_Etype (Temp, Target_Base);
1951 Insert_Action (Parent (Par),
1952 Make_Object_Declaration (Loc,
1953 Defining_Identifier => Temp,
1954 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1955 Expression => New_Copy_Tree (Par)),
1956 Suppress => All_Checks);
1959 Make_Raise_Constraint_Error (Loc,
1962 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1963 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1964 Reason => CE_Range_Check_Failed));
1965 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
1971 -- Get the (static) bounds of the target type
1973 Ifirst := Expr_Value (LB);
1974 Ilast := Expr_Value (HB);
1976 -- A simple optimization: if the expression is a universal literal,
1977 -- we can do the comparison with the bounds and the conversion to
1978 -- an integer type statically. The range checks are unchanged.
1980 if Nkind (Ck_Node) = N_Real_Literal
1981 and then Etype (Ck_Node) = Universal_Real
1982 and then Is_Integer_Type (Target_Typ)
1983 and then Nkind (Parent (Ck_Node)) = N_Type_Conversion
1986 Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node));
1989 if Int_Val <= Ilast and then Int_Val >= Ifirst then
1991 -- Conversion is safe
1993 Rewrite (Parent (Ck_Node),
1994 Make_Integer_Literal (Loc, UI_To_Int (Int_Val)));
1995 Analyze_And_Resolve (Parent (Ck_Node), Target_Typ);
2001 -- Check against lower bound
2003 if Truncate and then Ifirst > 0 then
2004 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
2008 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
2011 elsif abs (Ifirst) < Max_Bound then
2012 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
2013 Lo_OK := (Ifirst > 0);
2016 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
2017 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
2022 -- Lo_Chk := (X >= Lo)
2024 Lo_Chk := Make_Op_Ge (Loc,
2025 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2026 Right_Opnd => Make_Real_Literal (Loc, Lo));
2029 -- Lo_Chk := (X > Lo)
2031 Lo_Chk := Make_Op_Gt (Loc,
2032 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2033 Right_Opnd => Make_Real_Literal (Loc, Lo));
2036 -- Check against higher bound
2038 if Truncate and then Ilast < 0 then
2039 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
2043 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
2046 elsif abs (Ilast) < Max_Bound then
2047 Hi := UR_From_Uint (Ilast) + Ureal_Half;
2048 Hi_OK := (Ilast < 0);
2050 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
2051 Hi_OK := (Hi <= UR_From_Uint (Ilast));
2056 -- Hi_Chk := (X <= Hi)
2058 Hi_Chk := Make_Op_Le (Loc,
2059 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2060 Right_Opnd => Make_Real_Literal (Loc, Hi));
2063 -- Hi_Chk := (X < Hi)
2065 Hi_Chk := Make_Op_Lt (Loc,
2066 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2067 Right_Opnd => Make_Real_Literal (Loc, Hi));
2070 -- If the bounds of the target type are the same as those of the base
2071 -- type, the check is an overflow check as a range check is not
2072 -- performed in these cases.
2074 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
2075 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
2077 Reason := CE_Overflow_Check_Failed;
2079 Reason := CE_Range_Check_Failed;
2082 -- Raise CE if either conditions does not hold
2084 Insert_Action (Ck_Node,
2085 Make_Raise_Constraint_Error (Loc,
2086 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
2088 end Apply_Float_Conversion_Check;
2090 ------------------------
2091 -- Apply_Length_Check --
2092 ------------------------
2094 procedure Apply_Length_Check
2096 Target_Typ : Entity_Id;
2097 Source_Typ : Entity_Id := Empty)
2100 Apply_Selected_Length_Checks
2101 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
2102 end Apply_Length_Check;
2104 -------------------------------------
2105 -- Apply_Parameter_Aliasing_Checks --
2106 -------------------------------------
2108 procedure Apply_Parameter_Aliasing_Checks
2112 Loc : constant Source_Ptr := Sloc (Call);
2114 function May_Cause_Aliasing
2115 (Formal_1 : Entity_Id;
2116 Formal_2 : Entity_Id) return Boolean;
2117 -- Determine whether two formal parameters can alias each other
2118 -- depending on their modes.
2120 function Original_Actual (N : Node_Id) return Node_Id;
2121 -- The expander may replace an actual with a temporary for the sake of
2122 -- side effect removal. The temporary may hide a potential aliasing as
2123 -- it does not share the address of the actual. This routine attempts
2124 -- to retrieve the original actual.
2126 procedure Overlap_Check
2127 (Actual_1 : Node_Id;
2129 Formal_1 : Entity_Id;
2130 Formal_2 : Entity_Id;
2131 Check : in out Node_Id);
2132 -- Create a check to determine whether Actual_1 overlaps with Actual_2.
2133 -- If detailed exception messages are enabled, the check is augmented to
2134 -- provide information about the names of the corresponding formals. See
2135 -- the body for details. Actual_1 and Actual_2 denote the two actuals to
2136 -- be tested. Formal_1 and Formal_2 denote the corresponding formals.
2137 -- Check contains all and-ed simple tests generated so far or remains
2138 -- unchanged in the case of detailed exception messaged.
2140 ------------------------
2141 -- May_Cause_Aliasing --
2142 ------------------------
2144 function May_Cause_Aliasing
2145 (Formal_1 : Entity_Id;
2146 Formal_2 : Entity_Id) return Boolean
2149 -- The following combination cannot lead to aliasing
2151 -- Formal 1 Formal 2
2154 if Ekind (Formal_1) = E_In_Parameter
2156 Ekind (Formal_2) = E_In_Parameter
2160 -- The following combinations may lead to aliasing
2162 -- Formal 1 Formal 2
2172 end May_Cause_Aliasing;
2174 ---------------------
2175 -- Original_Actual --
2176 ---------------------
2178 function Original_Actual (N : Node_Id) return Node_Id is
2180 if Nkind (N) = N_Type_Conversion then
2181 return Expression (N);
2183 -- The expander created a temporary to capture the result of a type
2184 -- conversion where the expression is the real actual.
2186 elsif Nkind (N) = N_Identifier
2187 and then Present (Original_Node (N))
2188 and then Nkind (Original_Node (N)) = N_Type_Conversion
2190 return Expression (Original_Node (N));
2194 end Original_Actual;
2200 procedure Overlap_Check
2201 (Actual_1 : Node_Id;
2203 Formal_1 : Entity_Id;
2204 Formal_2 : Entity_Id;
2205 Check : in out Node_Id)
2208 ID_Casing : constant Casing_Type :=
2209 Identifier_Casing (Source_Index (Current_Sem_Unit));
2213 -- Actual_1'Overlaps_Storage (Actual_2)
2216 Make_Attribute_Reference (Loc,
2217 Prefix => New_Copy_Tree (Original_Actual (Actual_1)),
2218 Attribute_Name => Name_Overlaps_Storage,
2220 New_List (New_Copy_Tree (Original_Actual (Actual_2))));
2222 -- Generate the following check when detailed exception messages are
2225 -- if Actual_1'Overlaps_Storage (Actual_2) then
2226 -- raise Program_Error with <detailed message>;
2229 if Exception_Extra_Info then
2232 -- Do not generate location information for internal calls
2234 if Comes_From_Source (Call) then
2235 Store_String_Chars (Build_Location_String (Loc));
2236 Store_String_Char (' ');
2239 Store_String_Chars ("aliased parameters, actuals for """);
2241 Get_Name_String (Chars (Formal_1));
2242 Set_Casing (ID_Casing);
2243 Store_String_Chars (Name_Buffer (1 .. Name_Len));
2245 Store_String_Chars (""" and """);
2247 Get_Name_String (Chars (Formal_2));
2248 Set_Casing (ID_Casing);
2249 Store_String_Chars (Name_Buffer (1 .. Name_Len));
2251 Store_String_Chars (""" overlap");
2253 Insert_Action (Call,
2254 Make_If_Statement (Loc,
2256 Then_Statements => New_List (
2257 Make_Raise_Statement (Loc,
2259 New_Reference_To (Standard_Program_Error, Loc),
2260 Expression => Make_String_Literal (Loc, End_String)))));
2262 -- Create a sequence of overlapping checks by and-ing them all
2272 Right_Opnd => Cond);
2282 Formal_1 : Entity_Id;
2283 Formal_2 : Entity_Id;
2285 -- Start of processing for Apply_Parameter_Aliasing_Checks
2290 Actual_1 := First_Actual (Call);
2291 Formal_1 := First_Formal (Subp);
2292 while Present (Actual_1) and then Present (Formal_1) loop
2294 -- Ensure that the actual is an object that is not passed by value.
2295 -- Elementary types are always passed by value, therefore actuals of
2296 -- such types cannot lead to aliasing.
2298 if Is_Object_Reference (Original_Actual (Actual_1))
2299 and then not Is_Elementary_Type (Etype (Original_Actual (Actual_1)))
2301 Actual_2 := Next_Actual (Actual_1);
2302 Formal_2 := Next_Formal (Formal_1);
2303 while Present (Actual_2) and then Present (Formal_2) loop
2305 -- The other actual we are testing against must also denote
2306 -- a non pass-by-value object. Generate the check only when
2307 -- the mode of the two formals may lead to aliasing.
2309 if Is_Object_Reference (Original_Actual (Actual_2))
2311 Is_Elementary_Type (Etype (Original_Actual (Actual_2)))
2312 and then May_Cause_Aliasing (Formal_1, Formal_2)
2315 (Actual_1 => Actual_1,
2316 Actual_2 => Actual_2,
2317 Formal_1 => Formal_1,
2318 Formal_2 => Formal_2,
2322 Next_Actual (Actual_2);
2323 Next_Formal (Formal_2);
2327 Next_Actual (Actual_1);
2328 Next_Formal (Formal_1);
2331 -- Place a simple check right before the call
2333 if Present (Check) and then not Exception_Extra_Info then
2334 Insert_Action (Call,
2335 Make_Raise_Program_Error (Loc,
2337 Reason => PE_Aliased_Parameters));
2339 end Apply_Parameter_Aliasing_Checks;
2341 -------------------------------------
2342 -- Apply_Parameter_Validity_Checks --
2343 -------------------------------------
2345 procedure Apply_Parameter_Validity_Checks (Subp : Entity_Id) is
2346 Subp_Decl : Node_Id;
2348 procedure Add_Validity_Check
2349 (Context : Entity_Id;
2351 For_Result : Boolean := False);
2352 -- Add a single 'Valid[_Scalar] check which verifies the initialization
2353 -- of Context. PPC_Nam denotes the pre or post condition pragma name.
2354 -- Set flag For_Result when to verify the result of a function.
2356 procedure Build_PPC_Pragma (PPC_Nam : Name_Id; Check : Node_Id);
2357 -- Create a pre or post condition pragma with name PPC_Nam which
2358 -- tests expression Check.
2360 ------------------------
2361 -- Add_Validity_Check --
2362 ------------------------
2364 procedure Add_Validity_Check
2365 (Context : Entity_Id;
2367 For_Result : Boolean := False)
2369 Loc : constant Source_Ptr := Sloc (Subp);
2370 Typ : constant Entity_Id := Etype (Context);
2375 -- Pick the proper version of 'Valid depending on the type of the
2376 -- context. If the context is not eligible for such a check, return.
2378 if Is_Scalar_Type (Typ) then
2380 elsif not No_Scalar_Parts (Typ) then
2381 Nam := Name_Valid_Scalars;
2386 -- Step 1: Create the expression to verify the validity of the
2389 Check := New_Reference_To (Context, Loc);
2391 -- When processing a function result, use 'Result. Generate
2396 Make_Attribute_Reference (Loc,
2398 Attribute_Name => Name_Result);
2402 -- Context['Result]'Valid[_Scalars]
2405 Make_Attribute_Reference (Loc,
2407 Attribute_Name => Nam);
2409 -- Step 2: Create a pre or post condition pragma
2411 Build_PPC_Pragma (PPC_Nam, Check);
2412 end Add_Validity_Check;
2414 ----------------------
2415 -- Build_PPC_Pragma --
2416 ----------------------
2418 procedure Build_PPC_Pragma (PPC_Nam : Name_Id; Check : Node_Id) is
2419 Loc : constant Source_Ptr := Sloc (Subp);
2426 Pragma_Identifier => Make_Identifier (Loc, PPC_Nam),
2427 Pragma_Argument_Associations => New_List (
2428 Make_Pragma_Argument_Association (Loc,
2429 Chars => Name_Check,
2430 Expression => Check)));
2432 -- Add a message unless exception messages are suppressed
2434 if not Exception_Locations_Suppressed then
2435 Append_To (Pragma_Argument_Associations (Prag),
2436 Make_Pragma_Argument_Association (Loc,
2437 Chars => Name_Message,
2439 Make_String_Literal (Loc,
2440 Strval => "failed " & Get_Name_String (PPC_Nam) &
2441 " from " & Build_Location_String (Loc))));
2444 -- Insert the pragma in the tree
2446 if Nkind (Parent (Subp_Decl)) = N_Compilation_Unit then
2447 Add_Global_Declaration (Prag);
2450 -- PPC pragmas associated with subprogram bodies must be inserted in
2451 -- the declarative part of the body.
2453 elsif Nkind (Subp_Decl) = N_Subprogram_Body then
2454 Decls := Declarations (Subp_Decl);
2458 Set_Declarations (Subp_Decl, Decls);
2461 Prepend_To (Decls, Prag);
2463 -- Ensure the proper visibility of the subprogram body and its
2470 -- For subprogram declarations insert the PPC pragma right after the
2471 -- declarative node.
2474 Insert_After_And_Analyze (Subp_Decl, Prag);
2476 end Build_PPC_Pragma;
2481 Subp_Spec : Node_Id;
2483 -- Start of processing for Apply_Parameter_Validity_Checks
2486 -- Extract the subprogram specification and declaration nodes
2488 Subp_Spec := Parent (Subp);
2490 if Nkind (Subp_Spec) = N_Defining_Program_Unit_Name then
2491 Subp_Spec := Parent (Subp_Spec);
2494 Subp_Decl := Parent (Subp_Spec);
2496 if not Comes_From_Source (Subp)
2498 -- Do not process formal subprograms because the corresponding actual
2499 -- will receive the proper checks when the instance is analyzed.
2501 or else Is_Formal_Subprogram (Subp)
2503 -- Do not process imported subprograms since pre and post conditions
2504 -- are never verified on routines coming from a different language.
2506 or else Is_Imported (Subp)
2507 or else Is_Intrinsic_Subprogram (Subp)
2509 -- The PPC pragmas generated by this routine do not correspond to
2510 -- source aspects, therefore they cannot be applied to abstract
2513 or else Nkind (Subp_Decl) = N_Abstract_Subprogram_Declaration
2515 -- Do not consider subprogram renaminds because the renamed entity
2516 -- already has the proper PPC pragmas.
2518 or else Nkind (Subp_Decl) = N_Subprogram_Renaming_Declaration
2520 -- Do not process null procedures because there is no benefit of
2521 -- adding the checks to a no action routine.
2523 or else (Nkind (Subp_Spec) = N_Procedure_Specification
2524 and then Null_Present (Subp_Spec))
2529 -- Inspect all the formals applying aliasing and scalar initialization
2530 -- checks where applicable.
2532 Formal := First_Formal (Subp);
2533 while Present (Formal) loop
2535 -- Generate the following scalar initialization checks for each
2536 -- formal parameter:
2538 -- mode IN - Pre => Formal'Valid[_Scalars]
2539 -- mode IN OUT - Pre, Post => Formal'Valid[_Scalars]
2540 -- mode OUT - Post => Formal'Valid[_Scalars]
2542 if Check_Validity_Of_Parameters then
2543 if Ekind_In (Formal, E_In_Parameter, E_In_Out_Parameter) then
2544 Add_Validity_Check (Formal, Name_Precondition, False);
2547 if Ekind_In (Formal, E_In_Out_Parameter, E_Out_Parameter) then
2548 Add_Validity_Check (Formal, Name_Postcondition, False);
2552 Next_Formal (Formal);
2555 -- Generate following scalar initialization check for function result:
2557 -- Post => Subp'Result'Valid[_Scalars]
2559 if Check_Validity_Of_Parameters and then Ekind (Subp) = E_Function then
2560 Add_Validity_Check (Subp, Name_Postcondition, True);
2562 end Apply_Parameter_Validity_Checks;
2564 ---------------------------
2565 -- Apply_Predicate_Check --
2566 ---------------------------
2568 procedure Apply_Predicate_Check (N : Node_Id; Typ : Entity_Id) is
2572 if Present (Predicate_Function (Typ)) then
2574 -- A predicate check does not apply within internally generated
2575 -- subprograms, such as TSS functions.
2578 while Present (S) and then not Is_Subprogram (S) loop
2582 if Present (S) and then Get_TSS_Name (S) /= TSS_Null then
2585 -- If the check appears within the predicate function itself, it
2586 -- means that the user specified a check whose formal is the
2587 -- predicated subtype itself, rather than some covering type. This
2588 -- is likely to be a common error, and thus deserves a warning.
2590 elsif S = Predicate_Function (Typ) then
2592 ("predicate check includes a function call that "
2593 & "requires a predicate check??", Parent (N));
2595 ("\this will result in infinite recursion??", Parent (N));
2597 Make_Raise_Storage_Error (Sloc (N),
2598 Reason => SE_Infinite_Recursion));
2600 -- Here for normal case of predicate active
2603 -- If the type has a static predicate and the expression is known
2604 -- at compile time, see if the expression satisfies the predicate.
2606 Check_Expression_Against_Static_Predicate (N, Typ);
2609 Make_Predicate_Check (Typ, Duplicate_Subexpr (N)));
2612 end Apply_Predicate_Check;
2614 -----------------------
2615 -- Apply_Range_Check --
2616 -----------------------
2618 procedure Apply_Range_Check
2620 Target_Typ : Entity_Id;
2621 Source_Typ : Entity_Id := Empty)
2624 Apply_Selected_Range_Checks
2625 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
2626 end Apply_Range_Check;
2628 ------------------------------
2629 -- Apply_Scalar_Range_Check --
2630 ------------------------------
2632 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
2633 -- off if it is already set on.
2635 procedure Apply_Scalar_Range_Check
2637 Target_Typ : Entity_Id;
2638 Source_Typ : Entity_Id := Empty;
2639 Fixed_Int : Boolean := False)
2641 Parnt : constant Node_Id := Parent (Expr);
2643 Arr : Node_Id := Empty; -- initialize to prevent warning
2644 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
2647 Is_Subscr_Ref : Boolean;
2648 -- Set true if Expr is a subscript
2650 Is_Unconstrained_Subscr_Ref : Boolean;
2651 -- Set true if Expr is a subscript of an unconstrained array. In this
2652 -- case we do not attempt to do an analysis of the value against the
2653 -- range of the subscript, since we don't know the actual subtype.
2656 -- Set to True if Expr should be regarded as a real value even though
2657 -- the type of Expr might be discrete.
2659 procedure Bad_Value;
2660 -- Procedure called if value is determined to be out of range
2666 procedure Bad_Value is
2668 Apply_Compile_Time_Constraint_Error
2669 (Expr, "value not in range of}??", CE_Range_Check_Failed,
2674 -- Start of processing for Apply_Scalar_Range_Check
2677 -- Return if check obviously not needed
2680 -- Not needed inside generic
2684 -- Not needed if previous error
2686 or else Target_Typ = Any_Type
2687 or else Nkind (Expr) = N_Error
2689 -- Not needed for non-scalar type
2691 or else not Is_Scalar_Type (Target_Typ)
2693 -- Not needed if we know node raises CE already
2695 or else Raises_Constraint_Error (Expr)
2700 -- Now, see if checks are suppressed
2703 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
2705 if Is_Subscr_Ref then
2706 Arr := Prefix (Parnt);
2707 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
2709 if Is_Access_Type (Arr_Typ) then
2710 Arr_Typ := Designated_Type (Arr_Typ);
2714 if not Do_Range_Check (Expr) then
2716 -- Subscript reference. Check for Index_Checks suppressed
2718 if Is_Subscr_Ref then
2720 -- Check array type and its base type
2722 if Index_Checks_Suppressed (Arr_Typ)
2723 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
2727 -- Check array itself if it is an entity name
2729 elsif Is_Entity_Name (Arr)
2730 and then Index_Checks_Suppressed (Entity (Arr))
2734 -- Check expression itself if it is an entity name
2736 elsif Is_Entity_Name (Expr)
2737 and then Index_Checks_Suppressed (Entity (Expr))
2742 -- All other cases, check for Range_Checks suppressed
2745 -- Check target type and its base type
2747 if Range_Checks_Suppressed (Target_Typ)
2748 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
2752 -- Check expression itself if it is an entity name
2754 elsif Is_Entity_Name (Expr)
2755 and then Range_Checks_Suppressed (Entity (Expr))
2759 -- If Expr is part of an assignment statement, then check left
2760 -- side of assignment if it is an entity name.
2762 elsif Nkind (Parnt) = N_Assignment_Statement
2763 and then Is_Entity_Name (Name (Parnt))
2764 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
2771 -- Do not set range checks if they are killed
2773 if Nkind (Expr) = N_Unchecked_Type_Conversion
2774 and then Kill_Range_Check (Expr)
2779 -- Do not set range checks for any values from System.Scalar_Values
2780 -- since the whole idea of such values is to avoid checking them!
2782 if Is_Entity_Name (Expr)
2783 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
2788 -- Now see if we need a check
2790 if No (Source_Typ) then
2791 S_Typ := Etype (Expr);
2793 S_Typ := Source_Typ;
2796 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
2800 -- Ensure that the exponent is a natural. The flag is set only in formal
2801 -- verification mode as the expander takes care of this check and there
2802 -- is no expansion phase in GNATprove_Mode.
2804 -- Doesn't seem right to do this unconditionally, we should check the
2805 -- range of the exponent operand. If we do that, it seems like we should
2806 -- then set the flag unconditionally and have the expander check the
2807 -- flag to see whether to generate a check ???
2809 if GNATprove_Mode and then Nkind (Expr) = N_Op_Expon then
2810 Set_Do_Range_Check (Right_Opnd (Expr));
2813 Is_Unconstrained_Subscr_Ref :=
2814 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
2816 -- Special checks for floating-point type
2818 if Is_Floating_Point_Type (S_Typ) then
2820 -- Always do a range check if the source type includes infinities and
2821 -- the target type does not include infinities. We do not do this if
2822 -- range checks are killed.
2824 if Has_Infinities (S_Typ)
2825 and then not Has_Infinities (Target_Typ)
2827 Enable_Range_Check (Expr);
2829 -- Always do a range check for operators if option set
2831 elsif Check_Float_Overflow and then Nkind (Expr) in N_Op then
2832 Enable_Range_Check (Expr);
2836 -- Return if we know expression is definitely in the range of the target
2837 -- type as determined by Determine_Range. Right now we only do this for
2838 -- discrete types, and not fixed-point or floating-point types.
2840 -- The additional less-precise tests below catch these cases
2842 -- Note: skip this if we are given a source_typ, since the point of
2843 -- supplying a Source_Typ is to stop us looking at the expression.
2844 -- We could sharpen this test to be out parameters only ???
2846 if Is_Discrete_Type (Target_Typ)
2847 and then Is_Discrete_Type (Etype (Expr))
2848 and then not Is_Unconstrained_Subscr_Ref
2849 and then No (Source_Typ)
2852 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
2853 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
2858 if Compile_Time_Known_Value (Tlo)
2859 and then Compile_Time_Known_Value (Thi)
2862 Lov : constant Uint := Expr_Value (Tlo);
2863 Hiv : constant Uint := Expr_Value (Thi);
2866 -- If range is null, we for sure have a constraint error
2867 -- (we don't even need to look at the value involved,
2868 -- since all possible values will raise CE).
2875 -- Otherwise determine range of value
2877 Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True);
2881 -- If definitely in range, all OK
2883 if Lo >= Lov and then Hi <= Hiv then
2886 -- If definitely not in range, warn
2888 elsif Lov > Hi or else Hiv < Lo then
2892 -- Otherwise we don't know
2904 Is_Floating_Point_Type (S_Typ)
2905 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
2907 -- Check if we can determine at compile time whether Expr is in the
2908 -- range of the target type. Note that if S_Typ is within the bounds
2909 -- of Target_Typ then this must be the case. This check is meaningful
2910 -- only if this is not a conversion between integer and real types.
2912 if not Is_Unconstrained_Subscr_Ref
2913 and then Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
2915 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
2917 Is_In_Range (Expr, Target_Typ,
2918 Assume_Valid => True,
2919 Fixed_Int => Fixed_Int,
2920 Int_Real => Int_Real))
2924 elsif Is_Out_Of_Range (Expr, Target_Typ,
2925 Assume_Valid => True,
2926 Fixed_Int => Fixed_Int,
2927 Int_Real => Int_Real)
2932 -- Floating-point case
2933 -- In the floating-point case, we only do range checks if the type is
2934 -- constrained. We definitely do NOT want range checks for unconstrained
2935 -- types, since we want to have infinities
2937 elsif Is_Floating_Point_Type (S_Typ) then
2939 -- Normally, we only do range checks if the type is constrained. We do
2940 -- NOT want range checks for unconstrained types, since we want to have
2941 -- infinities. Override this decision in Check_Float_Overflow mode.
2943 if Is_Constrained (S_Typ) or else Check_Float_Overflow then
2944 Enable_Range_Check (Expr);
2947 -- For all other cases we enable a range check unconditionally
2950 Enable_Range_Check (Expr);
2953 end Apply_Scalar_Range_Check;
2955 ----------------------------------
2956 -- Apply_Selected_Length_Checks --
2957 ----------------------------------
2959 procedure Apply_Selected_Length_Checks
2961 Target_Typ : Entity_Id;
2962 Source_Typ : Entity_Id;
2963 Do_Static : Boolean)
2966 R_Result : Check_Result;
2969 Loc : constant Source_Ptr := Sloc (Ck_Node);
2970 Checks_On : constant Boolean :=
2971 (not Index_Checks_Suppressed (Target_Typ))
2972 or else (not Length_Checks_Suppressed (Target_Typ));
2975 if not Expander_Active then
2980 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
2982 for J in 1 .. 2 loop
2983 R_Cno := R_Result (J);
2984 exit when No (R_Cno);
2986 -- A length check may mention an Itype which is attached to a
2987 -- subsequent node. At the top level in a package this can cause
2988 -- an order-of-elaboration problem, so we make sure that the itype
2989 -- is referenced now.
2991 if Ekind (Current_Scope) = E_Package
2992 and then Is_Compilation_Unit (Current_Scope)
2994 Ensure_Defined (Target_Typ, Ck_Node);
2996 if Present (Source_Typ) then
2997 Ensure_Defined (Source_Typ, Ck_Node);
2999 elsif Is_Itype (Etype (Ck_Node)) then
3000 Ensure_Defined (Etype (Ck_Node), Ck_Node);
3004 -- If the item is a conditional raise of constraint error, then have
3005 -- a look at what check is being performed and ???
3007 if Nkind (R_Cno) = N_Raise_Constraint_Error
3008 and then Present (Condition (R_Cno))
3010 Cond := Condition (R_Cno);
3012 -- Case where node does not now have a dynamic check
3014 if not Has_Dynamic_Length_Check (Ck_Node) then
3016 -- If checks are on, just insert the check
3019 Insert_Action (Ck_Node, R_Cno);
3021 if not Do_Static then
3022 Set_Has_Dynamic_Length_Check (Ck_Node);
3025 -- If checks are off, then analyze the length check after
3026 -- temporarily attaching it to the tree in case the relevant
3027 -- condition can be evaluated at compile time. We still want a
3028 -- compile time warning in this case.
3031 Set_Parent (R_Cno, Ck_Node);
3036 -- Output a warning if the condition is known to be True
3038 if Is_Entity_Name (Cond)
3039 and then Entity (Cond) = Standard_True
3041 Apply_Compile_Time_Constraint_Error
3042 (Ck_Node, "wrong length for array of}??",
3043 CE_Length_Check_Failed,
3047 -- If we were only doing a static check, or if checks are not
3048 -- on, then we want to delete the check, since it is not needed.
3049 -- We do this by replacing the if statement by a null statement
3051 elsif Do_Static or else not Checks_On then
3052 Remove_Warning_Messages (R_Cno);
3053 Rewrite (R_Cno, Make_Null_Statement (Loc));
3057 Install_Static_Check (R_Cno, Loc);
3060 end Apply_Selected_Length_Checks;
3062 ---------------------------------
3063 -- Apply_Selected_Range_Checks --
3064 ---------------------------------
3066 procedure Apply_Selected_Range_Checks
3068 Target_Typ : Entity_Id;
3069 Source_Typ : Entity_Id;
3070 Do_Static : Boolean)
3073 R_Result : Check_Result;
3076 Loc : constant Source_Ptr := Sloc (Ck_Node);
3077 Checks_On : constant Boolean :=
3078 (not Index_Checks_Suppressed (Target_Typ))
3079 or else (not Range_Checks_Suppressed (Target_Typ));
3082 if not Expander_Active or else not Checks_On then
3087 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
3089 for J in 1 .. 2 loop
3091 R_Cno := R_Result (J);
3092 exit when No (R_Cno);
3094 -- If the item is a conditional raise of constraint error, then have
3095 -- a look at what check is being performed and ???
3097 if Nkind (R_Cno) = N_Raise_Constraint_Error
3098 and then Present (Condition (R_Cno))
3100 Cond := Condition (R_Cno);
3102 if not Has_Dynamic_Range_Check (Ck_Node) then
3103 Insert_Action (Ck_Node, R_Cno);
3105 if not Do_Static then
3106 Set_Has_Dynamic_Range_Check (Ck_Node);
3110 -- Output a warning if the condition is known to be True
3112 if Is_Entity_Name (Cond)
3113 and then Entity (Cond) = Standard_True
3115 -- Since an N_Range is technically not an expression, we have
3116 -- to set one of the bounds to C_E and then just flag the
3117 -- N_Range. The warning message will point to the lower bound
3118 -- and complain about a range, which seems OK.
3120 if Nkind (Ck_Node) = N_Range then
3121 Apply_Compile_Time_Constraint_Error
3122 (Low_Bound (Ck_Node), "static range out of bounds of}??",
3123 CE_Range_Check_Failed,
3127 Set_Raises_Constraint_Error (Ck_Node);
3130 Apply_Compile_Time_Constraint_Error
3131 (Ck_Node, "static value out of range of}?",
3132 CE_Range_Check_Failed,
3137 -- If we were only doing a static check, or if checks are not
3138 -- on, then we want to delete the check, since it is not needed.
3139 -- We do this by replacing the if statement by a null statement
3141 elsif Do_Static or else not Checks_On then
3142 Remove_Warning_Messages (R_Cno);
3143 Rewrite (R_Cno, Make_Null_Statement (Loc));
3147 Install_Static_Check (R_Cno, Loc);
3150 end Apply_Selected_Range_Checks;
3152 -------------------------------
3153 -- Apply_Static_Length_Check --
3154 -------------------------------
3156 procedure Apply_Static_Length_Check
3158 Target_Typ : Entity_Id;
3159 Source_Typ : Entity_Id := Empty)
3162 Apply_Selected_Length_Checks
3163 (Expr, Target_Typ, Source_Typ, Do_Static => True);
3164 end Apply_Static_Length_Check;
3166 -------------------------------------
3167 -- Apply_Subscript_Validity_Checks --
3168 -------------------------------------
3170 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
3174 pragma Assert (Nkind (Expr) = N_Indexed_Component);
3176 -- Loop through subscripts
3178 Sub := First (Expressions (Expr));
3179 while Present (Sub) loop
3181 -- Check one subscript. Note that we do not worry about enumeration
3182 -- type with holes, since we will convert the value to a Pos value
3183 -- for the subscript, and that convert will do the necessary validity
3186 Ensure_Valid (Sub, Holes_OK => True);
3188 -- Move to next subscript
3192 end Apply_Subscript_Validity_Checks;
3194 ----------------------------------
3195 -- Apply_Type_Conversion_Checks --
3196 ----------------------------------
3198 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
3199 Target_Type : constant Entity_Id := Etype (N);
3200 Target_Base : constant Entity_Id := Base_Type (Target_Type);
3201 Expr : constant Node_Id := Expression (N);
3203 Expr_Type : constant Entity_Id := Underlying_Type (Etype (Expr));
3204 -- Note: if Etype (Expr) is a private type without discriminants, its
3205 -- full view might have discriminants with defaults, so we need the
3206 -- full view here to retrieve the constraints.
3209 if Inside_A_Generic then
3212 -- Skip these checks if serious errors detected, there are some nasty
3213 -- situations of incomplete trees that blow things up.
3215 elsif Serious_Errors_Detected > 0 then
3218 -- Scalar type conversions of the form Target_Type (Expr) require a
3219 -- range check if we cannot be sure that Expr is in the base type of
3220 -- Target_Typ and also that Expr is in the range of Target_Typ. These
3221 -- are not quite the same condition from an implementation point of
3222 -- view, but clearly the second includes the first.
3224 elsif Is_Scalar_Type (Target_Type) then
3226 Conv_OK : constant Boolean := Conversion_OK (N);
3227 -- If the Conversion_OK flag on the type conversion is set and no
3228 -- floating point type is involved in the type conversion then
3229 -- fixed point values must be read as integral values.
3231 Float_To_Int : constant Boolean :=
3232 Is_Floating_Point_Type (Expr_Type)
3233 and then Is_Integer_Type (Target_Type);
3236 if not Overflow_Checks_Suppressed (Target_Base)
3237 and then not Overflow_Checks_Suppressed (Target_Type)
3239 In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK)
3240 and then not Float_To_Int
3242 Activate_Overflow_Check (N);
3245 if not Range_Checks_Suppressed (Target_Type)
3246 and then not Range_Checks_Suppressed (Expr_Type)
3248 if Float_To_Int then
3249 Apply_Float_Conversion_Check (Expr, Target_Type);
3251 Apply_Scalar_Range_Check
3252 (Expr, Target_Type, Fixed_Int => Conv_OK);
3254 -- If the target type has predicates, we need to indicate
3255 -- the need for a check, even if Determine_Range finds
3256 -- that the value is within bounds. This may be the case
3257 -- e.g for a division with a constant denominator.
3259 if Has_Predicates (Target_Type) then
3260 Enable_Range_Check (Expr);
3266 elsif Comes_From_Source (N)
3267 and then not Discriminant_Checks_Suppressed (Target_Type)
3268 and then Is_Record_Type (Target_Type)
3269 and then Is_Derived_Type (Target_Type)
3270 and then not Is_Tagged_Type (Target_Type)
3271 and then not Is_Constrained (Target_Type)
3272 and then Present (Stored_Constraint (Target_Type))
3274 -- An unconstrained derived type may have inherited discriminant.
3275 -- Build an actual discriminant constraint list using the stored
3276 -- constraint, to verify that the expression of the parent type
3277 -- satisfies the constraints imposed by the (unconstrained!)
3278 -- derived type. This applies to value conversions, not to view
3279 -- conversions of tagged types.
3282 Loc : constant Source_Ptr := Sloc (N);
3284 Constraint : Elmt_Id;
3285 Discr_Value : Node_Id;
3288 New_Constraints : constant Elist_Id := New_Elmt_List;
3289 Old_Constraints : constant Elist_Id :=
3290 Discriminant_Constraint (Expr_Type);
3293 Constraint := First_Elmt (Stored_Constraint (Target_Type));
3294 while Present (Constraint) loop
3295 Discr_Value := Node (Constraint);
3297 if Is_Entity_Name (Discr_Value)
3298 and then Ekind (Entity (Discr_Value)) = E_Discriminant
3300 Discr := Corresponding_Discriminant (Entity (Discr_Value));
3303 and then Scope (Discr) = Base_Type (Expr_Type)
3305 -- Parent is constrained by new discriminant. Obtain
3306 -- Value of original discriminant in expression. If the
3307 -- new discriminant has been used to constrain more than
3308 -- one of the stored discriminants, this will provide the
3309 -- required consistency check.
3312 (Make_Selected_Component (Loc,
3314 Duplicate_Subexpr_No_Checks
3315 (Expr, Name_Req => True),
3317 Make_Identifier (Loc, Chars (Discr))),
3321 -- Discriminant of more remote ancestor ???
3326 -- Derived type definition has an explicit value for this
3327 -- stored discriminant.
3331 (Duplicate_Subexpr_No_Checks (Discr_Value),
3335 Next_Elmt (Constraint);
3338 -- Use the unconstrained expression type to retrieve the
3339 -- discriminants of the parent, and apply momentarily the
3340 -- discriminant constraint synthesized above.
3342 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
3343 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
3344 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
3347 Make_Raise_Constraint_Error (Loc,
3349 Reason => CE_Discriminant_Check_Failed));
3352 -- For arrays, checks are set now, but conversions are applied during
3353 -- expansion, to take into accounts changes of representation. The
3354 -- checks become range checks on the base type or length checks on the
3355 -- subtype, depending on whether the target type is unconstrained or
3356 -- constrained. Note that the range check is put on the expression of a
3357 -- type conversion, while the length check is put on the type conversion
3360 elsif Is_Array_Type (Target_Type) then
3361 if Is_Constrained (Target_Type) then
3362 Set_Do_Length_Check (N);
3364 Set_Do_Range_Check (Expr);
3367 end Apply_Type_Conversion_Checks;
3369 ----------------------------------------------
3370 -- Apply_Universal_Integer_Attribute_Checks --
3371 ----------------------------------------------
3373 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
3374 Loc : constant Source_Ptr := Sloc (N);
3375 Typ : constant Entity_Id := Etype (N);
3378 if Inside_A_Generic then
3381 -- Nothing to do if checks are suppressed
3383 elsif Range_Checks_Suppressed (Typ)
3384 and then Overflow_Checks_Suppressed (Typ)
3388 -- Nothing to do if the attribute does not come from source. The
3389 -- internal attributes we generate of this type do not need checks,
3390 -- and furthermore the attempt to check them causes some circular
3391 -- elaboration orders when dealing with packed types.
3393 elsif not Comes_From_Source (N) then
3396 -- If the prefix is a selected component that depends on a discriminant
3397 -- the check may improperly expose a discriminant instead of using
3398 -- the bounds of the object itself. Set the type of the attribute to
3399 -- the base type of the context, so that a check will be imposed when
3400 -- needed (e.g. if the node appears as an index).
3402 elsif Nkind (Prefix (N)) = N_Selected_Component
3403 and then Ekind (Typ) = E_Signed_Integer_Subtype
3404 and then Depends_On_Discriminant (Scalar_Range (Typ))
3406 Set_Etype (N, Base_Type (Typ));
3408 -- Otherwise, replace the attribute node with a type conversion node
3409 -- whose expression is the attribute, retyped to universal integer, and
3410 -- whose subtype mark is the target type. The call to analyze this
3411 -- conversion will set range and overflow checks as required for proper
3412 -- detection of an out of range value.
3415 Set_Etype (N, Universal_Integer);
3416 Set_Analyzed (N, True);
3419 Make_Type_Conversion (Loc,
3420 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
3421 Expression => Relocate_Node (N)));
3423 Analyze_And_Resolve (N, Typ);
3426 end Apply_Universal_Integer_Attribute_Checks;
3428 -------------------------------------
3429 -- Atomic_Synchronization_Disabled --
3430 -------------------------------------
3432 -- Note: internally Disable/Enable_Atomic_Synchronization is implemented
3433 -- using a bogus check called Atomic_Synchronization. This is to make it
3434 -- more convenient to get exactly the same semantics as [Un]Suppress.
3436 function Atomic_Synchronization_Disabled (E : Entity_Id) return Boolean is
3438 -- If debug flag d.e is set, always return False, i.e. all atomic sync
3439 -- looks enabled, since it is never disabled.
3441 if Debug_Flag_Dot_E then
3444 -- If debug flag d.d is set then always return True, i.e. all atomic
3445 -- sync looks disabled, since it always tests True.
3447 elsif Debug_Flag_Dot_D then
3450 -- If entity present, then check result for that entity
3452 elsif Present (E) and then Checks_May_Be_Suppressed (E) then
3453 return Is_Check_Suppressed (E, Atomic_Synchronization);
3455 -- Otherwise result depends on current scope setting
3458 return Scope_Suppress.Suppress (Atomic_Synchronization);
3460 end Atomic_Synchronization_Disabled;
3462 -------------------------------
3463 -- Build_Discriminant_Checks --
3464 -------------------------------
3466 function Build_Discriminant_Checks
3468 T_Typ : Entity_Id) return Node_Id
3470 Loc : constant Source_Ptr := Sloc (N);
3473 Disc_Ent : Entity_Id;
3477 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
3479 ----------------------------------
3480 -- Aggregate_Discriminant_Value --
3481 ----------------------------------
3483 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
3487 -- The aggregate has been normalized with named associations. We use
3488 -- the Chars field to locate the discriminant to take into account
3489 -- discriminants in derived types, which carry the same name as those
3492 Assoc := First (Component_Associations (N));
3493 while Present (Assoc) loop
3494 if Chars (First (Choices (Assoc))) = Chars (Disc) then
3495 return Expression (Assoc);
3501 -- Discriminant must have been found in the loop above
3503 raise Program_Error;
3504 end Aggregate_Discriminant_Val;
3506 -- Start of processing for Build_Discriminant_Checks
3509 -- Loop through discriminants evolving the condition
3512 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
3514 -- For a fully private type, use the discriminants of the parent type
3516 if Is_Private_Type (T_Typ)
3517 and then No (Full_View (T_Typ))
3519 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
3521 Disc_Ent := First_Discriminant (T_Typ);
3524 while Present (Disc) loop
3525 Dval := Node (Disc);
3527 if Nkind (Dval) = N_Identifier
3528 and then Ekind (Entity (Dval)) = E_Discriminant
3530 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
3532 Dval := Duplicate_Subexpr_No_Checks (Dval);
3535 -- If we have an Unchecked_Union node, we can infer the discriminants
3538 if Is_Unchecked_Union (Base_Type (T_Typ)) then
3540 Get_Discriminant_Value (
3541 First_Discriminant (T_Typ),
3543 Stored_Constraint (T_Typ)));
3545 elsif Nkind (N) = N_Aggregate then
3547 Duplicate_Subexpr_No_Checks
3548 (Aggregate_Discriminant_Val (Disc_Ent));
3552 Make_Selected_Component (Loc,
3554 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
3556 Make_Identifier (Loc, Chars (Disc_Ent)));
3558 Set_Is_In_Discriminant_Check (Dref);
3561 Evolve_Or_Else (Cond,
3564 Right_Opnd => Dval));
3567 Next_Discriminant (Disc_Ent);
3571 end Build_Discriminant_Checks;
3577 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
3584 function Left_Expression (Op : Node_Id) return Node_Id;
3585 -- Return the relevant expression from the left operand of the given
3586 -- short circuit form: this is LO itself, except if LO is a qualified
3587 -- expression, a type conversion, or an expression with actions, in
3588 -- which case this is Left_Expression (Expression (LO)).
3590 ---------------------
3591 -- Left_Expression --
3592 ---------------------
3594 function Left_Expression (Op : Node_Id) return Node_Id is
3595 LE : Node_Id := Left_Opnd (Op);
3598 N_Qualified_Expression,
3600 N_Expression_With_Actions)
3602 LE := Expression (LE);
3606 end Left_Expression;
3608 -- Start of processing for Check_Needed
3611 -- Always check if not simple entity
3613 if Nkind (Nod) not in N_Has_Entity
3614 or else not Comes_From_Source (Nod)
3619 -- Look up tree for short circuit
3626 -- Done if out of subexpression (note that we allow generated stuff
3627 -- such as itype declarations in this context, to keep the loop going
3628 -- since we may well have generated such stuff in complex situations.
3629 -- Also done if no parent (probably an error condition, but no point
3630 -- in behaving nasty if we find it!)
3633 or else (K not in N_Subexpr and then Comes_From_Source (P))
3637 -- Or/Or Else case, where test is part of the right operand, or is
3638 -- part of one of the actions associated with the right operand, and
3639 -- the left operand is an equality test.
3641 elsif K = N_Op_Or then
3642 exit when N = Right_Opnd (P)
3643 and then Nkind (Left_Expression (P)) = N_Op_Eq;
3645 elsif K = N_Or_Else then
3646 exit when (N = Right_Opnd (P)
3649 and then List_Containing (N) = Actions (P)))
3650 and then Nkind (Left_Expression (P)) = N_Op_Eq;
3652 -- Similar test for the And/And then case, where the left operand
3653 -- is an inequality test.
3655 elsif K = N_Op_And then
3656 exit when N = Right_Opnd (P)
3657 and then Nkind (Left_Expression (P)) = N_Op_Ne;
3659 elsif K = N_And_Then then
3660 exit when (N = Right_Opnd (P)
3663 and then List_Containing (N) = Actions (P)))
3664 and then Nkind (Left_Expression (P)) = N_Op_Ne;
3670 -- If we fall through the loop, then we have a conditional with an
3671 -- appropriate test as its left operand, so look further.
3673 L := Left_Expression (P);
3675 -- L is an "=" or "/=" operator: extract its operands
3677 R := Right_Opnd (L);
3680 -- Left operand of test must match original variable
3682 if Nkind (L) not in N_Has_Entity
3683 or else Entity (L) /= Entity (Nod)
3688 -- Right operand of test must be key value (zero or null)
3691 when Access_Check =>
3692 if not Known_Null (R) then
3696 when Division_Check =>
3697 if not Compile_Time_Known_Value (R)
3698 or else Expr_Value (R) /= Uint_0
3704 raise Program_Error;
3707 -- Here we have the optimizable case, warn if not short-circuited
3709 if K = N_Op_And or else K = N_Op_Or then
3711 when Access_Check =>
3713 ("Constraint_Error may be raised (access check)??",
3715 when Division_Check =>
3717 ("Constraint_Error may be raised (zero divide)??",
3721 raise Program_Error;
3724 if K = N_Op_And then
3725 Error_Msg_N -- CODEFIX
3726 ("use `AND THEN` instead of AND??", P);
3728 Error_Msg_N -- CODEFIX
3729 ("use `OR ELSE` instead of OR??", P);
3732 -- If not short-circuited, we need the check
3736 -- If short-circuited, we can omit the check
3743 -----------------------------------
3744 -- Check_Valid_Lvalue_Subscripts --
3745 -----------------------------------
3747 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
3749 -- Skip this if range checks are suppressed
3751 if Range_Checks_Suppressed (Etype (Expr)) then
3754 -- Only do this check for expressions that come from source. We assume
3755 -- that expander generated assignments explicitly include any necessary
3756 -- checks. Note that this is not just an optimization, it avoids
3757 -- infinite recursions!
3759 elsif not Comes_From_Source (Expr) then
3762 -- For a selected component, check the prefix
3764 elsif Nkind (Expr) = N_Selected_Component then
3765 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
3768 -- Case of indexed component
3770 elsif Nkind (Expr) = N_Indexed_Component then
3771 Apply_Subscript_Validity_Checks (Expr);
3773 -- Prefix may itself be or contain an indexed component, and these
3774 -- subscripts need checking as well.
3776 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
3778 end Check_Valid_Lvalue_Subscripts;
3780 ----------------------------------
3781 -- Null_Exclusion_Static_Checks --
3782 ----------------------------------
3784 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
3785 Error_Node : Node_Id;
3787 Has_Null : constant Boolean := Has_Null_Exclusion (N);
3788 K : constant Node_Kind := Nkind (N);
3793 (K = N_Component_Declaration
3794 or else K = N_Discriminant_Specification
3795 or else K = N_Function_Specification
3796 or else K = N_Object_Declaration
3797 or else K = N_Parameter_Specification);
3799 if K = N_Function_Specification then
3800 Typ := Etype (Defining_Entity (N));
3802 Typ := Etype (Defining_Identifier (N));
3806 when N_Component_Declaration =>
3807 if Present (Access_Definition (Component_Definition (N))) then
3808 Error_Node := Component_Definition (N);
3810 Error_Node := Subtype_Indication (Component_Definition (N));
3813 when N_Discriminant_Specification =>
3814 Error_Node := Discriminant_Type (N);
3816 when N_Function_Specification =>
3817 Error_Node := Result_Definition (N);
3819 when N_Object_Declaration =>
3820 Error_Node := Object_Definition (N);
3822 when N_Parameter_Specification =>
3823 Error_Node := Parameter_Type (N);
3826 raise Program_Error;
3831 -- Enforce legality rule 3.10 (13): A null exclusion can only be
3832 -- applied to an access [sub]type.
3834 if not Is_Access_Type (Typ) then
3836 ("`NOT NULL` allowed only for an access type", Error_Node);
3838 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
3839 -- be applied to a [sub]type that does not exclude null already.
3841 elsif Can_Never_Be_Null (Typ)
3842 and then Comes_From_Source (Typ)
3845 ("`NOT NULL` not allowed (& already excludes null)",
3850 -- Check that null-excluding objects are always initialized, except for
3851 -- deferred constants, for which the expression will appear in the full
3854 if K = N_Object_Declaration
3855 and then No (Expression (N))
3856 and then not Constant_Present (N)
3857 and then not No_Initialization (N)
3859 -- Add an expression that assigns null. This node is needed by
3860 -- Apply_Compile_Time_Constraint_Error, which will replace this with
3861 -- a Constraint_Error node.
3863 Set_Expression (N, Make_Null (Sloc (N)));
3864 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
3866 Apply_Compile_Time_Constraint_Error
3867 (N => Expression (N),
3869 "(Ada 2005) null-excluding objects must be initialized??",
3870 Reason => CE_Null_Not_Allowed);
3873 -- Check that a null-excluding component, formal or object is not being
3874 -- assigned a null value. Otherwise generate a warning message and
3875 -- replace Expression (N) by an N_Constraint_Error node.
3877 if K /= N_Function_Specification then
3878 Expr := Expression (N);
3880 if Present (Expr) and then Known_Null (Expr) then
3882 when N_Component_Declaration |
3883 N_Discriminant_Specification =>
3884 Apply_Compile_Time_Constraint_Error
3886 Msg => "(Ada 2005) null not allowed " &
3887 "in null-excluding components??",
3888 Reason => CE_Null_Not_Allowed);
3890 when N_Object_Declaration =>
3891 Apply_Compile_Time_Constraint_Error
3893 Msg => "(Ada 2005) null not allowed " &
3894 "in null-excluding objects?",
3895 Reason => CE_Null_Not_Allowed);
3897 when N_Parameter_Specification =>
3898 Apply_Compile_Time_Constraint_Error
3900 Msg => "(Ada 2005) null not allowed " &
3901 "in null-excluding formals??",
3902 Reason => CE_Null_Not_Allowed);
3909 end Null_Exclusion_Static_Checks;
3911 ----------------------------------
3912 -- Conditional_Statements_Begin --
3913 ----------------------------------
3915 procedure Conditional_Statements_Begin is
3917 Saved_Checks_TOS := Saved_Checks_TOS + 1;
3919 -- If stack overflows, kill all checks, that way we know to simply reset
3920 -- the number of saved checks to zero on return. This should never occur
3923 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
3926 -- In the normal case, we just make a new stack entry saving the current
3927 -- number of saved checks for a later restore.
3930 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
3932 if Debug_Flag_CC then
3933 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
3937 end Conditional_Statements_Begin;
3939 --------------------------------
3940 -- Conditional_Statements_End --
3941 --------------------------------
3943 procedure Conditional_Statements_End is
3945 pragma Assert (Saved_Checks_TOS > 0);
3947 -- If the saved checks stack overflowed, then we killed all checks, so
3948 -- setting the number of saved checks back to zero is correct. This
3949 -- should never occur in practice.
3951 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
3952 Num_Saved_Checks := 0;
3954 -- In the normal case, restore the number of saved checks from the top
3958 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
3959 if Debug_Flag_CC then
3960 w ("Conditional_Statements_End: Num_Saved_Checks = ",
3965 Saved_Checks_TOS := Saved_Checks_TOS - 1;
3966 end Conditional_Statements_End;
3968 -------------------------
3969 -- Convert_From_Bignum --
3970 -------------------------
3972 function Convert_From_Bignum (N : Node_Id) return Node_Id is
3973 Loc : constant Source_Ptr := Sloc (N);
3976 pragma Assert (Is_RTE (Etype (N), RE_Bignum));
3978 -- Construct call From Bignum
3981 Make_Function_Call (Loc,
3983 New_Occurrence_Of (RTE (RE_From_Bignum), Loc),
3984 Parameter_Associations => New_List (Relocate_Node (N)));
3985 end Convert_From_Bignum;
3987 -----------------------
3988 -- Convert_To_Bignum --
3989 -----------------------
3991 function Convert_To_Bignum (N : Node_Id) return Node_Id is
3992 Loc : constant Source_Ptr := Sloc (N);
3995 -- Nothing to do if Bignum already except call Relocate_Node
3997 if Is_RTE (Etype (N), RE_Bignum) then
3998 return Relocate_Node (N);
4000 -- Otherwise construct call to To_Bignum, converting the operand to the
4001 -- required Long_Long_Integer form.
4004 pragma Assert (Is_Signed_Integer_Type (Etype (N)));
4006 Make_Function_Call (Loc,
4008 New_Occurrence_Of (RTE (RE_To_Bignum), Loc),
4009 Parameter_Associations => New_List (
4010 Convert_To (Standard_Long_Long_Integer, Relocate_Node (N))));
4012 end Convert_To_Bignum;
4014 ---------------------
4015 -- Determine_Range --
4016 ---------------------
4018 Cache_Size : constant := 2 ** 10;
4019 type Cache_Index is range 0 .. Cache_Size - 1;
4020 -- Determine size of below cache (power of 2 is more efficient!)
4022 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
4023 Determine_Range_Cache_V : array (Cache_Index) of Boolean;
4024 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
4025 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
4026 -- The above arrays are used to implement a small direct cache for
4027 -- Determine_Range calls. Because of the way Determine_Range recursively
4028 -- traces subexpressions, and because overflow checking calls the routine
4029 -- on the way up the tree, a quadratic behavior can otherwise be
4030 -- encountered in large expressions. The cache entry for node N is stored
4031 -- in the (N mod Cache_Size) entry, and can be validated by checking the
4032 -- actual node value stored there. The Range_Cache_V array records the
4033 -- setting of Assume_Valid for the cache entry.
4035 procedure Determine_Range
4040 Assume_Valid : Boolean := False)
4042 Typ : Entity_Id := Etype (N);
4043 -- Type to use, may get reset to base type for possibly invalid entity
4047 -- Lo and Hi bounds of left operand
4051 -- Lo and Hi bounds of right (or only) operand
4054 -- Temp variable used to hold a bound node
4057 -- High bound of base type of expression
4061 -- Refined values for low and high bounds, after tightening
4064 -- Used in lower level calls to indicate if call succeeded
4066 Cindex : Cache_Index;
4067 -- Used to search cache
4072 function OK_Operands return Boolean;
4073 -- Used for binary operators. Determines the ranges of the left and
4074 -- right operands, and if they are both OK, returns True, and puts
4075 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
4081 function OK_Operands return Boolean is
4084 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
4091 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4095 -- Start of processing for Determine_Range
4098 -- For temporary constants internally generated to remove side effects
4099 -- we must use the corresponding expression to determine the range of
4102 if Is_Entity_Name (N)
4103 and then Nkind (Parent (Entity (N))) = N_Object_Declaration
4104 and then Ekind (Entity (N)) = E_Constant
4105 and then Is_Internal_Name (Chars (Entity (N)))
4108 (Expression (Parent (Entity (N))), OK, Lo, Hi, Assume_Valid);
4112 -- Prevent junk warnings by initializing range variables
4119 -- If type is not defined, we can't determine its range
4123 -- We don't deal with anything except discrete types
4125 or else not Is_Discrete_Type (Typ)
4127 -- Ignore type for which an error has been posted, since range in
4128 -- this case may well be a bogosity deriving from the error. Also
4129 -- ignore if error posted on the reference node.
4131 or else Error_Posted (N) or else Error_Posted (Typ)
4137 -- For all other cases, we can determine the range
4141 -- If value is compile time known, then the possible range is the one
4142 -- value that we know this expression definitely has!
4144 if Compile_Time_Known_Value (N) then
4145 Lo := Expr_Value (N);
4150 -- Return if already in the cache
4152 Cindex := Cache_Index (N mod Cache_Size);
4154 if Determine_Range_Cache_N (Cindex) = N
4156 Determine_Range_Cache_V (Cindex) = Assume_Valid
4158 Lo := Determine_Range_Cache_Lo (Cindex);
4159 Hi := Determine_Range_Cache_Hi (Cindex);
4163 -- Otherwise, start by finding the bounds of the type of the expression,
4164 -- the value cannot be outside this range (if it is, then we have an
4165 -- overflow situation, which is a separate check, we are talking here
4166 -- only about the expression value).
4168 -- First a check, never try to find the bounds of a generic type, since
4169 -- these bounds are always junk values, and it is only valid to look at
4170 -- the bounds in an instance.
4172 if Is_Generic_Type (Typ) then
4177 -- First step, change to use base type unless we know the value is valid
4179 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
4180 or else Assume_No_Invalid_Values
4181 or else Assume_Valid
4185 Typ := Underlying_Type (Base_Type (Typ));
4188 -- Retrieve the base type. Handle the case where the base type is a
4189 -- private enumeration type.
4191 Btyp := Base_Type (Typ);
4193 if Is_Private_Type (Btyp) and then Present (Full_View (Btyp)) then
4194 Btyp := Full_View (Btyp);
4197 -- We use the actual bound unless it is dynamic, in which case use the
4198 -- corresponding base type bound if possible. If we can't get a bound
4199 -- then we figure we can't determine the range (a peculiar case, that
4200 -- perhaps cannot happen, but there is no point in bombing in this
4201 -- optimization circuit.
4203 -- First the low bound
4205 Bound := Type_Low_Bound (Typ);
4207 if Compile_Time_Known_Value (Bound) then
4208 Lo := Expr_Value (Bound);
4210 elsif Compile_Time_Known_Value (Type_Low_Bound (Btyp)) then
4211 Lo := Expr_Value (Type_Low_Bound (Btyp));
4218 -- Now the high bound
4220 Bound := Type_High_Bound (Typ);
4222 -- We need the high bound of the base type later on, and this should
4223 -- always be compile time known. Again, it is not clear that this
4224 -- can ever be false, but no point in bombing.
4226 if Compile_Time_Known_Value (Type_High_Bound (Btyp)) then
4227 Hbound := Expr_Value (Type_High_Bound (Btyp));
4235 -- If we have a static subtype, then that may have a tighter bound so
4236 -- use the upper bound of the subtype instead in this case.
4238 if Compile_Time_Known_Value (Bound) then
4239 Hi := Expr_Value (Bound);
4242 -- We may be able to refine this value in certain situations. If any
4243 -- refinement is possible, then Lor and Hir are set to possibly tighter
4244 -- bounds, and OK1 is set to True.
4248 -- For unary plus, result is limited by range of operand
4252 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
4254 -- For unary minus, determine range of operand, and negate it
4258 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4265 -- For binary addition, get range of each operand and do the
4266 -- addition to get the result range.
4270 Lor := Lo_Left + Lo_Right;
4271 Hir := Hi_Left + Hi_Right;
4274 -- Division is tricky. The only case we consider is where the right
4275 -- operand is a positive constant, and in this case we simply divide
4276 -- the bounds of the left operand
4280 if Lo_Right = Hi_Right
4281 and then Lo_Right > 0
4283 Lor := Lo_Left / Lo_Right;
4284 Hir := Hi_Left / Lo_Right;
4291 -- For binary subtraction, get range of each operand and do the worst
4292 -- case subtraction to get the result range.
4294 when N_Op_Subtract =>
4296 Lor := Lo_Left - Hi_Right;
4297 Hir := Hi_Left - Lo_Right;
4300 -- For MOD, if right operand is a positive constant, then result must
4301 -- be in the allowable range of mod results.
4305 if Lo_Right = Hi_Right
4306 and then Lo_Right /= 0
4308 if Lo_Right > 0 then
4310 Hir := Lo_Right - 1;
4312 else -- Lo_Right < 0
4313 Lor := Lo_Right + 1;
4322 -- For REM, if right operand is a positive constant, then result must
4323 -- be in the allowable range of mod results.
4327 if Lo_Right = Hi_Right
4328 and then Lo_Right /= 0
4331 Dval : constant Uint := (abs Lo_Right) - 1;
4334 -- The sign of the result depends on the sign of the
4335 -- dividend (but not on the sign of the divisor, hence
4336 -- the abs operation above).
4356 -- Attribute reference cases
4358 when N_Attribute_Reference =>
4359 case Attribute_Name (N) is
4361 -- For Pos/Val attributes, we can refine the range using the
4362 -- possible range of values of the attribute expression.
4364 when Name_Pos | Name_Val =>
4366 (First (Expressions (N)), OK1, Lor, Hir, Assume_Valid);
4368 -- For Length attribute, use the bounds of the corresponding
4369 -- index type to refine the range.
4373 Atyp : Entity_Id := Etype (Prefix (N));
4381 if Is_Access_Type (Atyp) then
4382 Atyp := Designated_Type (Atyp);
4385 -- For string literal, we know exact value
4387 if Ekind (Atyp) = E_String_Literal_Subtype then
4389 Lo := String_Literal_Length (Atyp);
4390 Hi := String_Literal_Length (Atyp);
4394 -- Otherwise check for expression given
4396 if No (Expressions (N)) then
4400 UI_To_Int (Expr_Value (First (Expressions (N))));
4403 Indx := First_Index (Atyp);
4404 for J in 2 .. Inum loop
4405 Indx := Next_Index (Indx);
4408 -- If the index type is a formal type or derived from
4409 -- one, the bounds are not static.
4411 if Is_Generic_Type (Root_Type (Etype (Indx))) then
4417 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU,
4422 (Type_High_Bound (Etype (Indx)), OK1, UL, UU,
4427 -- The maximum value for Length is the biggest
4428 -- possible gap between the values of the bounds.
4429 -- But of course, this value cannot be negative.
4431 Hir := UI_Max (Uint_0, UU - LL + 1);
4433 -- For constrained arrays, the minimum value for
4434 -- Length is taken from the actual value of the
4435 -- bounds, since the index will be exactly of this
4438 if Is_Constrained (Atyp) then
4439 Lor := UI_Max (Uint_0, UL - LU + 1);
4441 -- For an unconstrained array, the minimum value
4442 -- for length is always zero.
4451 -- No special handling for other attributes
4452 -- Probably more opportunities exist here???
4459 -- For type conversion from one discrete type to another, we can
4460 -- refine the range using the converted value.
4462 when N_Type_Conversion =>
4463 Determine_Range (Expression (N), OK1, Lor, Hir, Assume_Valid);
4465 -- Nothing special to do for all other expression kinds
4473 -- At this stage, if OK1 is true, then we know that the actual result of
4474 -- the computed expression is in the range Lor .. Hir. We can use this
4475 -- to restrict the possible range of results.
4479 -- If the refined value of the low bound is greater than the type
4480 -- high bound, then reset it to the more restrictive value. However,
4481 -- we do NOT do this for the case of a modular type where the
4482 -- possible upper bound on the value is above the base type high
4483 -- bound, because that means the result could wrap.
4486 and then not (Is_Modular_Integer_Type (Typ) and then Hir > Hbound)
4491 -- Similarly, if the refined value of the high bound is less than the
4492 -- value so far, then reset it to the more restrictive value. Again,
4493 -- we do not do this if the refined low bound is negative for a
4494 -- modular type, since this would wrap.
4497 and then not (Is_Modular_Integer_Type (Typ) and then Lor < Uint_0)
4503 -- Set cache entry for future call and we are all done
4505 Determine_Range_Cache_N (Cindex) := N;
4506 Determine_Range_Cache_V (Cindex) := Assume_Valid;
4507 Determine_Range_Cache_Lo (Cindex) := Lo;
4508 Determine_Range_Cache_Hi (Cindex) := Hi;
4511 -- If any exception occurs, it means that we have some bug in the compiler,
4512 -- possibly triggered by a previous error, or by some unforeseen peculiar
4513 -- occurrence. However, this is only an optimization attempt, so there is
4514 -- really no point in crashing the compiler. Instead we just decide, too
4515 -- bad, we can't figure out a range in this case after all.
4520 -- Debug flag K disables this behavior (useful for debugging)
4522 if Debug_Flag_K then
4530 end Determine_Range;
4532 ------------------------------------
4533 -- Discriminant_Checks_Suppressed --
4534 ------------------------------------
4536 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
4539 if Is_Unchecked_Union (E) then
4541 elsif Checks_May_Be_Suppressed (E) then
4542 return Is_Check_Suppressed (E, Discriminant_Check);
4546 return Scope_Suppress.Suppress (Discriminant_Check);
4547 end Discriminant_Checks_Suppressed;
4549 --------------------------------
4550 -- Division_Checks_Suppressed --
4551 --------------------------------
4553 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
4555 if Present (E) and then Checks_May_Be_Suppressed (E) then
4556 return Is_Check_Suppressed (E, Division_Check);
4558 return Scope_Suppress.Suppress (Division_Check);
4560 end Division_Checks_Suppressed;
4562 -----------------------------------
4563 -- Elaboration_Checks_Suppressed --
4564 -----------------------------------
4566 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
4568 -- The complication in this routine is that if we are in the dynamic
4569 -- model of elaboration, we also check All_Checks, since All_Checks
4570 -- does not set Elaboration_Check explicitly.
4573 if Kill_Elaboration_Checks (E) then
4576 elsif Checks_May_Be_Suppressed (E) then
4577 if Is_Check_Suppressed (E, Elaboration_Check) then
4579 elsif Dynamic_Elaboration_Checks then
4580 return Is_Check_Suppressed (E, All_Checks);
4587 if Scope_Suppress.Suppress (Elaboration_Check) then
4589 elsif Dynamic_Elaboration_Checks then
4590 return Scope_Suppress.Suppress (All_Checks);
4594 end Elaboration_Checks_Suppressed;
4596 ---------------------------
4597 -- Enable_Overflow_Check --
4598 ---------------------------
4600 procedure Enable_Overflow_Check (N : Node_Id) is
4601 Typ : constant Entity_Id := Base_Type (Etype (N));
4602 Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
4611 if Debug_Flag_CC then
4612 w ("Enable_Overflow_Check for node ", Int (N));
4613 Write_Str (" Source location = ");
4618 -- No check if overflow checks suppressed for type of node
4620 if Overflow_Checks_Suppressed (Etype (N)) then
4623 -- Nothing to do for unsigned integer types, which do not overflow
4625 elsif Is_Modular_Integer_Type (Typ) then
4629 -- This is the point at which processing for STRICT mode diverges
4630 -- from processing for MINIMIZED/ELIMINATED modes. This divergence is
4631 -- probably more extreme that it needs to be, but what is going on here
4632 -- is that when we introduced MINIMIZED/ELIMINATED modes, we wanted
4633 -- to leave the processing for STRICT mode untouched. There were
4634 -- two reasons for this. First it avoided any incompatible change of
4635 -- behavior. Second, it guaranteed that STRICT mode continued to be
4638 -- The big difference is that in STRICT mode there is a fair amount of
4639 -- circuitry to try to avoid setting the Do_Overflow_Check flag if we
4640 -- know that no check is needed. We skip all that in the two new modes,
4641 -- since really overflow checking happens over a whole subtree, and we
4642 -- do the corresponding optimizations later on when applying the checks.
4644 if Mode in Minimized_Or_Eliminated then
4645 if not (Overflow_Checks_Suppressed (Etype (N)))
4646 and then not (Is_Entity_Name (N)
4647 and then Overflow_Checks_Suppressed (Entity (N)))
4649 Activate_Overflow_Check (N);
4652 if Debug_Flag_CC then
4653 w ("Minimized/Eliminated mode");
4659 -- Remainder of processing is for STRICT case, and is unchanged from
4660 -- earlier versions preceding the addition of MINIMIZED/ELIMINATED.
4662 -- Nothing to do if the range of the result is known OK. We skip this
4663 -- for conversions, since the caller already did the check, and in any
4664 -- case the condition for deleting the check for a type conversion is
4667 if Nkind (N) /= N_Type_Conversion then
4668 Determine_Range (N, OK, Lo, Hi, Assume_Valid => True);
4670 -- Note in the test below that we assume that the range is not OK
4671 -- if a bound of the range is equal to that of the type. That's not
4672 -- quite accurate but we do this for the following reasons:
4674 -- a) The way that Determine_Range works, it will typically report
4675 -- the bounds of the value as being equal to the bounds of the
4676 -- type, because it either can't tell anything more precise, or
4677 -- does not think it is worth the effort to be more precise.
4679 -- b) It is very unusual to have a situation in which this would
4680 -- generate an unnecessary overflow check (an example would be
4681 -- a subtype with a range 0 .. Integer'Last - 1 to which the
4682 -- literal value one is added).
4684 -- c) The alternative is a lot of special casing in this routine
4685 -- which would partially duplicate Determine_Range processing.
4688 and then Lo > Expr_Value (Type_Low_Bound (Typ))
4689 and then Hi < Expr_Value (Type_High_Bound (Typ))
4691 if Debug_Flag_CC then
4692 w ("No overflow check required");
4699 -- If not in optimizing mode, set flag and we are done. We are also done
4700 -- (and just set the flag) if the type is not a discrete type, since it
4701 -- is not worth the effort to eliminate checks for other than discrete
4702 -- types. In addition, we take this same path if we have stored the
4703 -- maximum number of checks possible already (a very unlikely situation,
4704 -- but we do not want to blow up!)
4706 if Optimization_Level = 0
4707 or else not Is_Discrete_Type (Etype (N))
4708 or else Num_Saved_Checks = Saved_Checks'Last
4710 Activate_Overflow_Check (N);
4712 if Debug_Flag_CC then
4713 w ("Optimization off");
4719 -- Otherwise evaluate and check the expression
4724 Target_Type => Empty,
4730 if Debug_Flag_CC then
4731 w ("Called Find_Check");
4735 w (" Check_Num = ", Chk);
4736 w (" Ent = ", Int (Ent));
4737 Write_Str (" Ofs = ");
4742 -- If check is not of form to optimize, then set flag and we are done
4745 Activate_Overflow_Check (N);
4749 -- If check is already performed, then return without setting flag
4752 if Debug_Flag_CC then
4753 w ("Check suppressed!");
4759 -- Here we will make a new entry for the new check
4761 Activate_Overflow_Check (N);
4762 Num_Saved_Checks := Num_Saved_Checks + 1;
4763 Saved_Checks (Num_Saved_Checks) :=
4768 Target_Type => Empty);
4770 if Debug_Flag_CC then
4771 w ("Make new entry, check number = ", Num_Saved_Checks);
4772 w (" Entity = ", Int (Ent));
4773 Write_Str (" Offset = ");
4775 w (" Check_Type = O");
4776 w (" Target_Type = Empty");
4779 -- If we get an exception, then something went wrong, probably because of
4780 -- an error in the structure of the tree due to an incorrect program. Or it
4781 -- may be a bug in the optimization circuit. In either case the safest
4782 -- thing is simply to set the check flag unconditionally.
4786 Activate_Overflow_Check (N);
4788 if Debug_Flag_CC then
4789 w (" exception occurred, overflow flag set");
4793 end Enable_Overflow_Check;
4795 ------------------------
4796 -- Enable_Range_Check --
4797 ------------------------
4799 procedure Enable_Range_Check (N : Node_Id) is
4808 -- Return if unchecked type conversion with range check killed. In this
4809 -- case we never set the flag (that's what Kill_Range_Check is about!)
4811 if Nkind (N) = N_Unchecked_Type_Conversion
4812 and then Kill_Range_Check (N)
4817 -- Do not set range check flag if parent is assignment statement or
4818 -- object declaration with Suppress_Assignment_Checks flag set
4820 if Nkind_In (Parent (N), N_Assignment_Statement, N_Object_Declaration)
4821 and then Suppress_Assignment_Checks (Parent (N))
4826 -- Check for various cases where we should suppress the range check
4828 -- No check if range checks suppressed for type of node
4830 if Present (Etype (N))
4831 and then Range_Checks_Suppressed (Etype (N))
4835 -- No check if node is an entity name, and range checks are suppressed
4836 -- for this entity, or for the type of this entity.
4838 elsif Is_Entity_Name (N)
4839 and then (Range_Checks_Suppressed (Entity (N))
4840 or else Range_Checks_Suppressed (Etype (Entity (N))))
4844 -- No checks if index of array, and index checks are suppressed for
4845 -- the array object or the type of the array.
4847 elsif Nkind (Parent (N)) = N_Indexed_Component then
4849 Pref : constant Node_Id := Prefix (Parent (N));
4851 if Is_Entity_Name (Pref)
4852 and then Index_Checks_Suppressed (Entity (Pref))
4855 elsif Index_Checks_Suppressed (Etype (Pref)) then
4861 -- Debug trace output
4863 if Debug_Flag_CC then
4864 w ("Enable_Range_Check for node ", Int (N));
4865 Write_Str (" Source location = ");
4870 -- If not in optimizing mode, set flag and we are done. We are also done
4871 -- (and just set the flag) if the type is not a discrete type, since it
4872 -- is not worth the effort to eliminate checks for other than discrete
4873 -- types. In addition, we take this same path if we have stored the
4874 -- maximum number of checks possible already (a very unlikely situation,
4875 -- but we do not want to blow up!)
4877 if Optimization_Level = 0
4878 or else No (Etype (N))
4879 or else not Is_Discrete_Type (Etype (N))
4880 or else Num_Saved_Checks = Saved_Checks'Last
4882 Activate_Range_Check (N);
4884 if Debug_Flag_CC then
4885 w ("Optimization off");
4891 -- Otherwise find out the target type
4895 -- For assignment, use left side subtype
4897 if Nkind (P) = N_Assignment_Statement
4898 and then Expression (P) = N
4900 Ttyp := Etype (Name (P));
4902 -- For indexed component, use subscript subtype
4904 elsif Nkind (P) = N_Indexed_Component then
4911 Atyp := Etype (Prefix (P));
4913 if Is_Access_Type (Atyp) then
4914 Atyp := Designated_Type (Atyp);
4916 -- If the prefix is an access to an unconstrained array,
4917 -- perform check unconditionally: it depends on the bounds of
4918 -- an object and we cannot currently recognize whether the test
4919 -- may be redundant.
4921 if not Is_Constrained (Atyp) then
4922 Activate_Range_Check (N);
4926 -- Ditto if the prefix is an explicit dereference whose designated
4927 -- type is unconstrained.
4929 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
4930 and then not Is_Constrained (Atyp)
4932 Activate_Range_Check (N);
4936 Indx := First_Index (Atyp);
4937 Subs := First (Expressions (P));
4940 Ttyp := Etype (Indx);
4949 -- For now, ignore all other cases, they are not so interesting
4952 if Debug_Flag_CC then
4953 w (" target type not found, flag set");
4956 Activate_Range_Check (N);
4960 -- Evaluate and check the expression
4965 Target_Type => Ttyp,
4971 if Debug_Flag_CC then
4972 w ("Called Find_Check");
4973 w ("Target_Typ = ", Int (Ttyp));
4977 w (" Check_Num = ", Chk);
4978 w (" Ent = ", Int (Ent));
4979 Write_Str (" Ofs = ");
4984 -- If check is not of form to optimize, then set flag and we are done
4987 if Debug_Flag_CC then
4988 w (" expression not of optimizable type, flag set");
4991 Activate_Range_Check (N);
4995 -- If check is already performed, then return without setting flag
4998 if Debug_Flag_CC then
4999 w ("Check suppressed!");
5005 -- Here we will make a new entry for the new check
5007 Activate_Range_Check (N);
5008 Num_Saved_Checks := Num_Saved_Checks + 1;
5009 Saved_Checks (Num_Saved_Checks) :=
5014 Target_Type => Ttyp);
5016 if Debug_Flag_CC then
5017 w ("Make new entry, check number = ", Num_Saved_Checks);
5018 w (" Entity = ", Int (Ent));
5019 Write_Str (" Offset = ");
5021 w (" Check_Type = R");
5022 w (" Target_Type = ", Int (Ttyp));
5023 pg (Union_Id (Ttyp));
5026 -- If we get an exception, then something went wrong, probably because of
5027 -- an error in the structure of the tree due to an incorrect program. Or
5028 -- it may be a bug in the optimization circuit. In either case the safest
5029 -- thing is simply to set the check flag unconditionally.
5033 Activate_Range_Check (N);
5035 if Debug_Flag_CC then
5036 w (" exception occurred, range flag set");
5040 end Enable_Range_Check;
5046 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
5047 Typ : constant Entity_Id := Etype (Expr);
5050 -- Ignore call if we are not doing any validity checking
5052 if not Validity_Checks_On then
5055 -- Ignore call if range or validity checks suppressed on entity or type
5057 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
5060 -- No check required if expression is from the expander, we assume the
5061 -- expander will generate whatever checks are needed. Note that this is
5062 -- not just an optimization, it avoids infinite recursions!
5064 -- Unchecked conversions must be checked, unless they are initialized
5065 -- scalar values, as in a component assignment in an init proc.
5067 -- In addition, we force a check if Force_Validity_Checks is set
5069 elsif not Comes_From_Source (Expr)
5070 and then not Force_Validity_Checks
5071 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
5072 or else Kill_Range_Check (Expr))
5076 -- No check required if expression is known to have valid value
5078 elsif Expr_Known_Valid (Expr) then
5081 -- Ignore case of enumeration with holes where the flag is set not to
5082 -- worry about holes, since no special validity check is needed
5084 elsif Is_Enumeration_Type (Typ)
5085 and then Has_Non_Standard_Rep (Typ)
5090 -- No check required on the left-hand side of an assignment
5092 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
5093 and then Expr = Name (Parent (Expr))
5097 -- No check on a universal real constant. The context will eventually
5098 -- convert it to a machine number for some target type, or report an
5101 elsif Nkind (Expr) = N_Real_Literal
5102 and then Etype (Expr) = Universal_Real
5106 -- If the expression denotes a component of a packed boolean array,
5107 -- no possible check applies. We ignore the old ACATS chestnuts that
5108 -- involve Boolean range True..True.
5110 -- Note: validity checks are generated for expressions that yield a
5111 -- scalar type, when it is possible to create a value that is outside of
5112 -- the type. If this is a one-bit boolean no such value exists. This is
5113 -- an optimization, and it also prevents compiler blowing up during the
5114 -- elaboration of improperly expanded packed array references.
5116 elsif Nkind (Expr) = N_Indexed_Component
5117 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
5118 and then Root_Type (Etype (Expr)) = Standard_Boolean
5122 -- For an expression with actions, we want to insert the validity check
5123 -- on the final Expression.
5125 elsif Nkind (Expr) = N_Expression_With_Actions then
5126 Ensure_Valid (Expression (Expr));
5129 -- An annoying special case. If this is an out parameter of a scalar
5130 -- type, then the value is not going to be accessed, therefore it is
5131 -- inappropriate to do any validity check at the call site.
5134 -- Only need to worry about scalar types
5136 if Is_Scalar_Type (Typ) then
5146 -- Find actual argument (which may be a parameter association)
5147 -- and the parent of the actual argument (the call statement)
5152 if Nkind (P) = N_Parameter_Association then
5157 -- Only need to worry if we are argument of a procedure call
5158 -- since functions don't have out parameters. If this is an
5159 -- indirect or dispatching call, get signature from the
5162 if Nkind (P) = N_Procedure_Call_Statement then
5163 L := Parameter_Associations (P);
5165 if Is_Entity_Name (Name (P)) then
5166 E := Entity (Name (P));
5168 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
5169 E := Etype (Name (P));
5172 -- Only need to worry if there are indeed actuals, and if
5173 -- this could be a procedure call, otherwise we cannot get a
5174 -- match (either we are not an argument, or the mode of the
5175 -- formal is not OUT). This test also filters out the
5178 if Is_Non_Empty_List (L)
5179 and then Is_Subprogram (E)
5181 -- This is the loop through parameters, looking for an
5182 -- OUT parameter for which we are the argument.
5184 F := First_Formal (E);
5186 while Present (F) loop
5187 if Ekind (F) = E_Out_Parameter and then A = N then
5200 -- If this is a boolean expression, only its elementary operands need
5201 -- checking: if they are valid, a boolean or short-circuit operation
5202 -- with them will be valid as well.
5204 if Base_Type (Typ) = Standard_Boolean
5206 (Nkind (Expr) in N_Op or else Nkind (Expr) in N_Short_Circuit)
5211 -- If we fall through, a validity check is required
5213 Insert_Valid_Check (Expr);
5215 if Is_Entity_Name (Expr)
5216 and then Safe_To_Capture_Value (Expr, Entity (Expr))
5218 Set_Is_Known_Valid (Entity (Expr));
5222 ----------------------
5223 -- Expr_Known_Valid --
5224 ----------------------
5226 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
5227 Typ : constant Entity_Id := Etype (Expr);
5230 -- Non-scalar types are always considered valid, since they never give
5231 -- rise to the issues of erroneous or bounded error behavior that are
5232 -- the concern. In formal reference manual terms the notion of validity
5233 -- only applies to scalar types. Note that even when packed arrays are
5234 -- represented using modular types, they are still arrays semantically,
5235 -- so they are also always valid (in particular, the unused bits can be
5236 -- random rubbish without affecting the validity of the array value).
5238 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
5241 -- If no validity checking, then everything is considered valid
5243 elsif not Validity_Checks_On then
5246 -- Floating-point types are considered valid unless floating-point
5247 -- validity checks have been specifically turned on.
5249 elsif Is_Floating_Point_Type (Typ)
5250 and then not Validity_Check_Floating_Point
5254 -- If the expression is the value of an object that is known to be
5255 -- valid, then clearly the expression value itself is valid.
5257 elsif Is_Entity_Name (Expr)
5258 and then Is_Known_Valid (Entity (Expr))
5262 -- References to discriminants are always considered valid. The value
5263 -- of a discriminant gets checked when the object is built. Within the
5264 -- record, we consider it valid, and it is important to do so, since
5265 -- otherwise we can try to generate bogus validity checks which
5266 -- reference discriminants out of scope. Discriminants of concurrent
5267 -- types are excluded for the same reason.
5269 elsif Is_Entity_Name (Expr)
5270 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
5274 -- If the type is one for which all values are known valid, then we are
5275 -- sure that the value is valid except in the slightly odd case where
5276 -- the expression is a reference to a variable whose size has been
5277 -- explicitly set to a value greater than the object size.
5279 elsif Is_Known_Valid (Typ) then
5280 if Is_Entity_Name (Expr)
5281 and then Ekind (Entity (Expr)) = E_Variable
5282 and then Esize (Entity (Expr)) > Esize (Typ)
5289 -- Integer and character literals always have valid values, where
5290 -- appropriate these will be range checked in any case.
5292 elsif Nkind (Expr) = N_Integer_Literal
5294 Nkind (Expr) = N_Character_Literal
5298 -- Real literals are assumed to be valid in VM targets
5300 elsif VM_Target /= No_VM
5301 and then Nkind (Expr) = N_Real_Literal
5305 -- If we have a type conversion or a qualification of a known valid
5306 -- value, then the result will always be valid.
5308 elsif Nkind (Expr) = N_Type_Conversion
5310 Nkind (Expr) = N_Qualified_Expression
5312 return Expr_Known_Valid (Expression (Expr));
5314 -- The result of any operator is always considered valid, since we
5315 -- assume the necessary checks are done by the operator. For operators
5316 -- on floating-point operations, we must also check when the operation
5317 -- is the right-hand side of an assignment, or is an actual in a call.
5319 elsif Nkind (Expr) in N_Op then
5320 if Is_Floating_Point_Type (Typ)
5321 and then Validity_Check_Floating_Point
5323 (Nkind (Parent (Expr)) = N_Assignment_Statement
5324 or else Nkind (Parent (Expr)) = N_Function_Call
5325 or else Nkind (Parent (Expr)) = N_Parameter_Association)
5332 -- The result of a membership test is always valid, since it is true or
5333 -- false, there are no other possibilities.
5335 elsif Nkind (Expr) in N_Membership_Test then
5338 -- For all other cases, we do not know the expression is valid
5343 end Expr_Known_Valid;
5349 procedure Find_Check
5351 Check_Type : Character;
5352 Target_Type : Entity_Id;
5353 Entry_OK : out Boolean;
5354 Check_Num : out Nat;
5355 Ent : out Entity_Id;
5358 function Within_Range_Of
5359 (Target_Type : Entity_Id;
5360 Check_Type : Entity_Id) return Boolean;
5361 -- Given a requirement for checking a range against Target_Type, and
5362 -- and a range Check_Type against which a check has already been made,
5363 -- determines if the check against check type is sufficient to ensure
5364 -- that no check against Target_Type is required.
5366 ---------------------
5367 -- Within_Range_Of --
5368 ---------------------
5370 function Within_Range_Of
5371 (Target_Type : Entity_Id;
5372 Check_Type : Entity_Id) return Boolean
5375 if Target_Type = Check_Type then
5380 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
5381 Thi : constant Node_Id := Type_High_Bound (Target_Type);
5382 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
5383 Chi : constant Node_Id := Type_High_Bound (Check_Type);
5387 or else (Compile_Time_Known_Value (Tlo)
5389 Compile_Time_Known_Value (Clo)
5391 Expr_Value (Clo) >= Expr_Value (Tlo)))
5394 or else (Compile_Time_Known_Value (Thi)
5396 Compile_Time_Known_Value (Chi)
5398 Expr_Value (Chi) <= Expr_Value (Clo)))
5406 end Within_Range_Of;
5408 -- Start of processing for Find_Check
5411 -- Establish default, in case no entry is found
5415 -- Case of expression is simple entity reference
5417 if Is_Entity_Name (Expr) then
5418 Ent := Entity (Expr);
5421 -- Case of expression is entity + known constant
5423 elsif Nkind (Expr) = N_Op_Add
5424 and then Compile_Time_Known_Value (Right_Opnd (Expr))
5425 and then Is_Entity_Name (Left_Opnd (Expr))
5427 Ent := Entity (Left_Opnd (Expr));
5428 Ofs := Expr_Value (Right_Opnd (Expr));
5430 -- Case of expression is entity - known constant
5432 elsif Nkind (Expr) = N_Op_Subtract
5433 and then Compile_Time_Known_Value (Right_Opnd (Expr))
5434 and then Is_Entity_Name (Left_Opnd (Expr))
5436 Ent := Entity (Left_Opnd (Expr));
5437 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
5439 -- Any other expression is not of the right form
5448 -- Come here with expression of appropriate form, check if entity is an
5449 -- appropriate one for our purposes.
5451 if (Ekind (Ent) = E_Variable
5452 or else Is_Constant_Object (Ent))
5453 and then not Is_Library_Level_Entity (Ent)
5461 -- See if there is matching check already
5463 for J in reverse 1 .. Num_Saved_Checks loop
5465 SC : Saved_Check renames Saved_Checks (J);
5468 if SC.Killed = False
5469 and then SC.Entity = Ent
5470 and then SC.Offset = Ofs
5471 and then SC.Check_Type = Check_Type
5472 and then Within_Range_Of (Target_Type, SC.Target_Type)
5480 -- If we fall through entry was not found
5485 ---------------------------------
5486 -- Generate_Discriminant_Check --
5487 ---------------------------------
5489 -- Note: the code for this procedure is derived from the
5490 -- Emit_Discriminant_Check Routine in trans.c.
5492 procedure Generate_Discriminant_Check (N : Node_Id) is
5493 Loc : constant Source_Ptr := Sloc (N);
5494 Pref : constant Node_Id := Prefix (N);
5495 Sel : constant Node_Id := Selector_Name (N);
5497 Orig_Comp : constant Entity_Id :=
5498 Original_Record_Component (Entity (Sel));
5499 -- The original component to be checked
5501 Discr_Fct : constant Entity_Id :=
5502 Discriminant_Checking_Func (Orig_Comp);
5503 -- The discriminant checking function
5506 -- One discriminant to be checked in the type
5508 Real_Discr : Entity_Id;
5509 -- Actual discriminant in the call
5511 Pref_Type : Entity_Id;
5512 -- Type of relevant prefix (ignoring private/access stuff)
5515 -- List of arguments for function call
5518 -- Keep track of the formal corresponding to the actual we build for
5519 -- each discriminant, in order to be able to perform the necessary type
5523 -- Selected component reference for checking function argument
5526 Pref_Type := Etype (Pref);
5528 -- Force evaluation of the prefix, so that it does not get evaluated
5529 -- twice (once for the check, once for the actual reference). Such a
5530 -- double evaluation is always a potential source of inefficiency,
5531 -- and is functionally incorrect in the volatile case, or when the
5532 -- prefix may have side-effects. An entity or a component of an
5533 -- entity requires no evaluation.
5535 if Is_Entity_Name (Pref) then
5536 if Treat_As_Volatile (Entity (Pref)) then
5537 Force_Evaluation (Pref, Name_Req => True);
5540 elsif Treat_As_Volatile (Etype (Pref)) then
5541 Force_Evaluation (Pref, Name_Req => True);
5543 elsif Nkind (Pref) = N_Selected_Component
5544 and then Is_Entity_Name (Prefix (Pref))
5549 Force_Evaluation (Pref, Name_Req => True);
5552 -- For a tagged type, use the scope of the original component to
5553 -- obtain the type, because ???
5555 if Is_Tagged_Type (Scope (Orig_Comp)) then
5556 Pref_Type := Scope (Orig_Comp);
5558 -- For an untagged derived type, use the discriminants of the parent
5559 -- which have been renamed in the derivation, possibly by a one-to-many
5560 -- discriminant constraint. For non-tagged type, initially get the Etype
5564 if Is_Derived_Type (Pref_Type)
5565 and then Number_Discriminants (Pref_Type) /=
5566 Number_Discriminants (Etype (Base_Type (Pref_Type)))
5568 Pref_Type := Etype (Base_Type (Pref_Type));
5572 -- We definitely should have a checking function, This routine should
5573 -- not be called if no discriminant checking function is present.
5575 pragma Assert (Present (Discr_Fct));
5577 -- Create the list of the actual parameters for the call. This list
5578 -- is the list of the discriminant fields of the record expression to
5579 -- be discriminant checked.
5582 Formal := First_Formal (Discr_Fct);
5583 Discr := First_Discriminant (Pref_Type);
5584 while Present (Discr) loop
5586 -- If we have a corresponding discriminant field, and a parent
5587 -- subtype is present, then we want to use the corresponding
5588 -- discriminant since this is the one with the useful value.
5590 if Present (Corresponding_Discriminant (Discr))
5591 and then Ekind (Pref_Type) = E_Record_Type
5592 and then Present (Parent_Subtype (Pref_Type))
5594 Real_Discr := Corresponding_Discriminant (Discr);
5596 Real_Discr := Discr;
5599 -- Construct the reference to the discriminant
5602 Make_Selected_Component (Loc,
5604 Unchecked_Convert_To (Pref_Type,
5605 Duplicate_Subexpr (Pref)),
5606 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
5608 -- Manually analyze and resolve this selected component. We really
5609 -- want it just as it appears above, and do not want the expander
5610 -- playing discriminal games etc with this reference. Then we append
5611 -- the argument to the list we are gathering.
5613 Set_Etype (Scomp, Etype (Real_Discr));
5614 Set_Analyzed (Scomp, True);
5615 Append_To (Args, Convert_To (Etype (Formal), Scomp));
5617 Next_Formal_With_Extras (Formal);
5618 Next_Discriminant (Discr);
5621 -- Now build and insert the call
5624 Make_Raise_Constraint_Error (Loc,
5626 Make_Function_Call (Loc,
5627 Name => New_Occurrence_Of (Discr_Fct, Loc),
5628 Parameter_Associations => Args),
5629 Reason => CE_Discriminant_Check_Failed));
5630 end Generate_Discriminant_Check;
5632 ---------------------------
5633 -- Generate_Index_Checks --
5634 ---------------------------
5636 procedure Generate_Index_Checks (N : Node_Id) is
5638 function Entity_Of_Prefix return Entity_Id;
5639 -- Returns the entity of the prefix of N (or Empty if not found)
5641 ----------------------
5642 -- Entity_Of_Prefix --
5643 ----------------------
5645 function Entity_Of_Prefix return Entity_Id is
5650 while not Is_Entity_Name (P) loop
5651 if not Nkind_In (P, N_Selected_Component,
5652 N_Indexed_Component)
5661 end Entity_Of_Prefix;
5665 Loc : constant Source_Ptr := Sloc (N);
5666 A : constant Node_Id := Prefix (N);
5667 A_Ent : constant Entity_Id := Entity_Of_Prefix;
5670 -- Start of processing for Generate_Index_Checks
5673 -- Ignore call if the prefix is not an array since we have a serious
5674 -- error in the sources. Ignore it also if index checks are suppressed
5675 -- for array object or type.
5677 if not Is_Array_Type (Etype (A))
5678 or else (Present (A_Ent)
5679 and then Index_Checks_Suppressed (A_Ent))
5680 or else Index_Checks_Suppressed (Etype (A))
5684 -- The indexed component we are dealing with contains 'Loop_Entry in its
5685 -- prefix. This case arises when analysis has determined that constructs
5688 -- Prefix'Loop_Entry (Expr)
5689 -- Prefix'Loop_Entry (Expr1, Expr2, ... ExprN)
5691 -- require rewriting for error detection purposes. A side effect of this
5692 -- action is the generation of index checks that mention 'Loop_Entry.
5693 -- Delay the generation of the check until 'Loop_Entry has been properly
5694 -- expanded. This is done in Expand_Loop_Entry_Attributes.
5696 elsif Nkind (Prefix (N)) = N_Attribute_Reference
5697 and then Attribute_Name (Prefix (N)) = Name_Loop_Entry
5702 -- Generate a raise of constraint error with the appropriate reason and
5703 -- a condition of the form:
5705 -- Base_Type (Sub) not in Array'Range (Subscript)
5707 -- Note that the reason we generate the conversion to the base type here
5708 -- is that we definitely want the range check to take place, even if it
5709 -- looks like the subtype is OK. Optimization considerations that allow
5710 -- us to omit the check have already been taken into account in the
5711 -- setting of the Do_Range_Check flag earlier on.
5713 Sub := First (Expressions (N));
5715 -- Handle string literals
5717 if Ekind (Etype (A)) = E_String_Literal_Subtype then
5718 if Do_Range_Check (Sub) then
5719 Set_Do_Range_Check (Sub, False);
5721 -- For string literals we obtain the bounds of the string from the
5722 -- associated subtype.
5725 Make_Raise_Constraint_Error (Loc,
5729 Convert_To (Base_Type (Etype (Sub)),
5730 Duplicate_Subexpr_Move_Checks (Sub)),
5732 Make_Attribute_Reference (Loc,
5733 Prefix => New_Reference_To (Etype (A), Loc),
5734 Attribute_Name => Name_Range)),
5735 Reason => CE_Index_Check_Failed));
5742 A_Idx : Node_Id := Empty;
5749 A_Idx := First_Index (Etype (A));
5751 while Present (Sub) loop
5752 if Do_Range_Check (Sub) then
5753 Set_Do_Range_Check (Sub, False);
5755 -- Force evaluation except for the case of a simple name of
5756 -- a non-volatile entity.
5758 if not Is_Entity_Name (Sub)
5759 or else Treat_As_Volatile (Entity (Sub))
5761 Force_Evaluation (Sub);
5764 if Nkind (A_Idx) = N_Range then
5767 elsif Nkind (A_Idx) = N_Identifier
5768 or else Nkind (A_Idx) = N_Expanded_Name
5770 A_Range := Scalar_Range (Entity (A_Idx));
5772 else pragma Assert (Nkind (A_Idx) = N_Subtype_Indication);
5773 A_Range := Range_Expression (Constraint (A_Idx));
5776 -- For array objects with constant bounds we can generate
5777 -- the index check using the bounds of the type of the index
5780 and then Ekind (A_Ent) = E_Variable
5781 and then Is_Constant_Bound (Low_Bound (A_Range))
5782 and then Is_Constant_Bound (High_Bound (A_Range))
5785 Make_Attribute_Reference (Loc,
5787 New_Reference_To (Etype (A_Idx), Loc),
5788 Attribute_Name => Name_Range);
5790 -- For arrays with non-constant bounds we cannot generate
5791 -- the index check using the bounds of the type of the index
5792 -- since it may reference discriminants of some enclosing
5793 -- type. We obtain the bounds directly from the prefix
5800 Num := New_List (Make_Integer_Literal (Loc, Ind));
5804 Make_Attribute_Reference (Loc,
5806 Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
5807 Attribute_Name => Name_Range,
5808 Expressions => Num);
5812 Make_Raise_Constraint_Error (Loc,
5816 Convert_To (Base_Type (Etype (Sub)),
5817 Duplicate_Subexpr_Move_Checks (Sub)),
5818 Right_Opnd => Range_N),
5819 Reason => CE_Index_Check_Failed));
5822 A_Idx := Next_Index (A_Idx);
5828 end Generate_Index_Checks;
5830 --------------------------
5831 -- Generate_Range_Check --
5832 --------------------------
5834 procedure Generate_Range_Check
5836 Target_Type : Entity_Id;
5837 Reason : RT_Exception_Code)
5839 Loc : constant Source_Ptr := Sloc (N);
5840 Source_Type : constant Entity_Id := Etype (N);
5841 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
5842 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
5845 -- First special case, if the source type is already within the range
5846 -- of the target type, then no check is needed (probably we should have
5847 -- stopped Do_Range_Check from being set in the first place, but better
5848 -- late than never in preventing junk code!
5850 if In_Subrange_Of (Source_Type, Target_Type)
5852 -- We do NOT apply this if the source node is a literal, since in this
5853 -- case the literal has already been labeled as having the subtype of
5857 (Nkind_In (N, N_Integer_Literal, N_Real_Literal, N_Character_Literal)
5860 and then Ekind (Entity (N)) = E_Enumeration_Literal))
5862 -- Also do not apply this for floating-point if Check_Float_Overflow
5865 (Is_Floating_Point_Type (Source_Type) and Check_Float_Overflow)
5870 -- We need a check, so force evaluation of the node, so that it does
5871 -- not get evaluated twice (once for the check, once for the actual
5872 -- reference). Such a double evaluation is always a potential source
5873 -- of inefficiency, and is functionally incorrect in the volatile case.
5875 if not Is_Entity_Name (N) or else Treat_As_Volatile (Entity (N)) then
5876 Force_Evaluation (N);
5879 -- The easiest case is when Source_Base_Type and Target_Base_Type are
5880 -- the same since in this case we can simply do a direct check of the
5881 -- value of N against the bounds of Target_Type.
5883 -- [constraint_error when N not in Target_Type]
5885 -- Note: this is by far the most common case, for example all cases of
5886 -- checks on the RHS of assignments are in this category, but not all
5887 -- cases are like this. Notably conversions can involve two types.
5889 if Source_Base_Type = Target_Base_Type then
5891 Make_Raise_Constraint_Error (Loc,
5894 Left_Opnd => Duplicate_Subexpr (N),
5895 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
5898 -- Next test for the case where the target type is within the bounds
5899 -- of the base type of the source type, since in this case we can
5900 -- simply convert these bounds to the base type of T to do the test.
5902 -- [constraint_error when N not in
5903 -- Source_Base_Type (Target_Type'First)
5905 -- Source_Base_Type(Target_Type'Last))]
5907 -- The conversions will always work and need no check
5909 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
5910 -- of converting from an enumeration value to an integer type, such as
5911 -- occurs for the case of generating a range check on Enum'Val(Exp)
5912 -- (which used to be handled by gigi). This is OK, since the conversion
5913 -- itself does not require a check.
5915 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
5917 Make_Raise_Constraint_Error (Loc,
5920 Left_Opnd => Duplicate_Subexpr (N),
5925 Unchecked_Convert_To (Source_Base_Type,
5926 Make_Attribute_Reference (Loc,
5928 New_Occurrence_Of (Target_Type, Loc),
5929 Attribute_Name => Name_First)),
5932 Unchecked_Convert_To (Source_Base_Type,
5933 Make_Attribute_Reference (Loc,
5935 New_Occurrence_Of (Target_Type, Loc),
5936 Attribute_Name => Name_Last)))),
5939 -- Note that at this stage we now that the Target_Base_Type is not in
5940 -- the range of the Source_Base_Type (since even the Target_Type itself
5941 -- is not in this range). It could still be the case that Source_Type is
5942 -- in range of the target base type since we have not checked that case.
5944 -- If that is the case, we can freely convert the source to the target,
5945 -- and then test the target result against the bounds.
5947 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
5949 -- We make a temporary to hold the value of the converted value
5950 -- (converted to the base type), and then we will do the test against
5953 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
5954 -- [constraint_error when Tnn not in Target_Type]
5956 -- Then the conversion itself is replaced by an occurrence of Tnn
5959 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
5962 Insert_Actions (N, New_List (
5963 Make_Object_Declaration (Loc,
5964 Defining_Identifier => Tnn,
5965 Object_Definition =>
5966 New_Occurrence_Of (Target_Base_Type, Loc),
5967 Constant_Present => True,
5969 Make_Type_Conversion (Loc,
5970 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
5971 Expression => Duplicate_Subexpr (N))),
5973 Make_Raise_Constraint_Error (Loc,
5976 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
5977 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
5979 Reason => Reason)));
5981 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
5983 -- Set the type of N, because the declaration for Tnn might not
5984 -- be analyzed yet, as is the case if N appears within a record
5985 -- declaration, as a discriminant constraint or expression.
5987 Set_Etype (N, Target_Base_Type);
5990 -- At this stage, we know that we have two scalar types, which are
5991 -- directly convertible, and where neither scalar type has a base
5992 -- range that is in the range of the other scalar type.
5994 -- The only way this can happen is with a signed and unsigned type.
5995 -- So test for these two cases:
5998 -- Case of the source is unsigned and the target is signed
6000 if Is_Unsigned_Type (Source_Base_Type)
6001 and then not Is_Unsigned_Type (Target_Base_Type)
6003 -- If the source is unsigned and the target is signed, then we
6004 -- know that the source is not shorter than the target (otherwise
6005 -- the source base type would be in the target base type range).
6007 -- In other words, the unsigned type is either the same size as
6008 -- the target, or it is larger. It cannot be smaller.
6011 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
6013 -- We only need to check the low bound if the low bound of the
6014 -- target type is non-negative. If the low bound of the target
6015 -- type is negative, then we know that we will fit fine.
6017 -- If the high bound of the target type is negative, then we
6018 -- know we have a constraint error, since we can't possibly
6019 -- have a negative source.
6021 -- With these two checks out of the way, we can do the check
6022 -- using the source type safely
6024 -- This is definitely the most annoying case!
6026 -- [constraint_error
6027 -- when (Target_Type'First >= 0
6029 -- N < Source_Base_Type (Target_Type'First))
6030 -- or else Target_Type'Last < 0
6031 -- or else N > Source_Base_Type (Target_Type'Last)];
6033 -- We turn off all checks since we know that the conversions
6034 -- will work fine, given the guards for negative values.
6037 Make_Raise_Constraint_Error (Loc,
6043 Left_Opnd => Make_Op_Ge (Loc,
6045 Make_Attribute_Reference (Loc,
6047 New_Occurrence_Of (Target_Type, Loc),
6048 Attribute_Name => Name_First),
6049 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
6053 Left_Opnd => Duplicate_Subexpr (N),
6055 Convert_To (Source_Base_Type,
6056 Make_Attribute_Reference (Loc,
6058 New_Occurrence_Of (Target_Type, Loc),
6059 Attribute_Name => Name_First)))),
6064 Make_Attribute_Reference (Loc,
6065 Prefix => New_Occurrence_Of (Target_Type, Loc),
6066 Attribute_Name => Name_Last),
6067 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
6071 Left_Opnd => Duplicate_Subexpr (N),
6073 Convert_To (Source_Base_Type,
6074 Make_Attribute_Reference (Loc,
6075 Prefix => New_Occurrence_Of (Target_Type, Loc),
6076 Attribute_Name => Name_Last)))),
6079 Suppress => All_Checks);
6081 -- Only remaining possibility is that the source is signed and
6082 -- the target is unsigned.
6085 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
6086 and then Is_Unsigned_Type (Target_Base_Type));
6088 -- If the source is signed and the target is unsigned, then we
6089 -- know that the target is not shorter than the source (otherwise
6090 -- the target base type would be in the source base type range).
6092 -- In other words, the unsigned type is either the same size as
6093 -- the target, or it is larger. It cannot be smaller.
6095 -- Clearly we have an error if the source value is negative since
6096 -- no unsigned type can have negative values. If the source type
6097 -- is non-negative, then the check can be done using the target
6100 -- Tnn : constant Target_Base_Type (N) := Target_Type;
6102 -- [constraint_error
6103 -- when N < 0 or else Tnn not in Target_Type];
6105 -- We turn off all checks for the conversion of N to the target
6106 -- base type, since we generate the explicit check to ensure that
6107 -- the value is non-negative
6110 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
6113 Insert_Actions (N, New_List (
6114 Make_Object_Declaration (Loc,
6115 Defining_Identifier => Tnn,
6116 Object_Definition =>
6117 New_Occurrence_Of (Target_Base_Type, Loc),
6118 Constant_Present => True,
6120 Make_Unchecked_Type_Conversion (Loc,
6122 New_Occurrence_Of (Target_Base_Type, Loc),
6123 Expression => Duplicate_Subexpr (N))),
6125 Make_Raise_Constraint_Error (Loc,
6130 Left_Opnd => Duplicate_Subexpr (N),
6131 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
6135 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
6137 New_Occurrence_Of (Target_Type, Loc))),
6140 Suppress => All_Checks);
6142 -- Set the Etype explicitly, because Insert_Actions may have
6143 -- placed the declaration in the freeze list for an enclosing
6144 -- construct, and thus it is not analyzed yet.
6146 Set_Etype (Tnn, Target_Base_Type);
6147 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
6151 end Generate_Range_Check;
6157 function Get_Check_Id (N : Name_Id) return Check_Id is
6159 -- For standard check name, we can do a direct computation
6161 if N in First_Check_Name .. Last_Check_Name then
6162 return Check_Id (N - (First_Check_Name - 1));
6164 -- For non-standard names added by pragma Check_Name, search table
6167 for J in All_Checks + 1 .. Check_Names.Last loop
6168 if Check_Names.Table (J) = N then
6174 -- No matching name found
6179 ---------------------
6180 -- Get_Discriminal --
6181 ---------------------
6183 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
6184 Loc : constant Source_Ptr := Sloc (E);
6189 -- The bound can be a bona fide parameter of a protected operation,
6190 -- rather than a prival encoded as an in-parameter.
6192 if No (Discriminal_Link (Entity (Bound))) then
6196 -- Climb the scope stack looking for an enclosing protected type. If
6197 -- we run out of scopes, return the bound itself.
6200 while Present (Sc) loop
6201 if Sc = Standard_Standard then
6204 elsif Ekind (Sc) = E_Protected_Type then
6211 D := First_Discriminant (Sc);
6212 while Present (D) loop
6213 if Chars (D) = Chars (Bound) then
6214 return New_Occurrence_Of (Discriminal (D), Loc);
6217 Next_Discriminant (D);
6221 end Get_Discriminal;
6223 ----------------------
6224 -- Get_Range_Checks --
6225 ----------------------
6227 function Get_Range_Checks
6229 Target_Typ : Entity_Id;
6230 Source_Typ : Entity_Id := Empty;
6231 Warn_Node : Node_Id := Empty) return Check_Result
6234 return Selected_Range_Checks
6235 (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
6236 end Get_Range_Checks;
6242 function Guard_Access
6245 Ck_Node : Node_Id) return Node_Id
6248 if Nkind (Cond) = N_Or_Else then
6249 Set_Paren_Count (Cond, 1);
6252 if Nkind (Ck_Node) = N_Allocator then
6259 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
6260 Right_Opnd => Make_Null (Loc)),
6261 Right_Opnd => Cond);
6265 -----------------------------
6266 -- Index_Checks_Suppressed --
6267 -----------------------------
6269 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
6271 if Present (E) and then Checks_May_Be_Suppressed (E) then
6272 return Is_Check_Suppressed (E, Index_Check);
6274 return Scope_Suppress.Suppress (Index_Check);
6276 end Index_Checks_Suppressed;
6282 procedure Initialize is
6284 for J in Determine_Range_Cache_N'Range loop
6285 Determine_Range_Cache_N (J) := Empty;
6290 for J in Int range 1 .. All_Checks loop
6291 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
6295 -------------------------
6296 -- Insert_Range_Checks --
6297 -------------------------
6299 procedure Insert_Range_Checks
6300 (Checks : Check_Result;
6302 Suppress_Typ : Entity_Id;
6303 Static_Sloc : Source_Ptr := No_Location;
6304 Flag_Node : Node_Id := Empty;
6305 Do_Before : Boolean := False)
6307 Internal_Flag_Node : Node_Id := Flag_Node;
6308 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
6310 Check_Node : Node_Id;
6311 Checks_On : constant Boolean :=
6312 (not Index_Checks_Suppressed (Suppress_Typ))
6313 or else (not Range_Checks_Suppressed (Suppress_Typ));
6316 -- For now we just return if Checks_On is false, however this should be
6317 -- enhanced to check for an always True value in the condition and to
6318 -- generate a compilation warning???
6320 if not Expander_Active or not Checks_On then
6324 if Static_Sloc = No_Location then
6325 Internal_Static_Sloc := Sloc (Node);
6328 if No (Flag_Node) then
6329 Internal_Flag_Node := Node;
6332 for J in 1 .. 2 loop
6333 exit when No (Checks (J));
6335 if Nkind (Checks (J)) = N_Raise_Constraint_Error
6336 and then Present (Condition (Checks (J)))
6338 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
6339 Check_Node := Checks (J);
6340 Mark_Rewrite_Insertion (Check_Node);
6343 Insert_Before_And_Analyze (Node, Check_Node);
6345 Insert_After_And_Analyze (Node, Check_Node);
6348 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
6353 Make_Raise_Constraint_Error (Internal_Static_Sloc,
6354 Reason => CE_Range_Check_Failed);
6355 Mark_Rewrite_Insertion (Check_Node);
6358 Insert_Before_And_Analyze (Node, Check_Node);
6360 Insert_After_And_Analyze (Node, Check_Node);
6364 end Insert_Range_Checks;
6366 ------------------------
6367 -- Insert_Valid_Check --
6368 ------------------------
6370 procedure Insert_Valid_Check (Expr : Node_Id) is
6371 Loc : constant Source_Ptr := Sloc (Expr);
6372 Typ : constant Entity_Id := Etype (Expr);
6376 -- Do not insert if checks off, or if not checking validity or
6377 -- if expression is known to be valid
6379 if not Validity_Checks_On
6380 or else Range_Or_Validity_Checks_Suppressed (Expr)
6381 or else Expr_Known_Valid (Expr)
6386 -- Do not insert checks within a predicate function. This will arise
6387 -- if the current unit and the predicate function are being compiled
6388 -- with validity checks enabled.
6390 if Present (Predicate_Function (Typ))
6391 and then Current_Scope = Predicate_Function (Typ)
6396 -- If we have a checked conversion, then validity check applies to
6397 -- the expression inside the conversion, not the result, since if
6398 -- the expression inside is valid, then so is the conversion result.
6401 while Nkind (Exp) = N_Type_Conversion loop
6402 Exp := Expression (Exp);
6405 -- We are about to insert the validity check for Exp. We save and
6406 -- reset the Do_Range_Check flag over this validity check, and then
6407 -- put it back for the final original reference (Exp may be rewritten).
6410 DRC : constant Boolean := Do_Range_Check (Exp);
6415 Set_Do_Range_Check (Exp, False);
6417 -- Force evaluation to avoid multiple reads for atomic/volatile
6419 if Is_Entity_Name (Exp)
6420 and then Is_Volatile (Entity (Exp))
6422 Force_Evaluation (Exp, Name_Req => True);
6425 -- Build the prefix for the 'Valid call
6427 PV := Duplicate_Subexpr_No_Checks (Exp, Name_Req => True);
6429 -- A rather specialized kludge. If PV is an analyzed expression
6430 -- which is an indexed component of a packed array that has not
6431 -- been properly expanded, turn off its Analyzed flag to make sure
6432 -- it gets properly reexpanded.
6434 -- The reason this arises is that Duplicate_Subexpr_No_Checks did
6435 -- an analyze with the old parent pointer. This may point e.g. to
6436 -- a subprogram call, which deactivates this expansion.
6439 and then Nkind (PV) = N_Indexed_Component
6440 and then Present (Packed_Array_Type (Etype (Prefix (PV))))
6442 Set_Analyzed (PV, False);
6445 -- Build the raise CE node to check for validity
6448 Make_Raise_Constraint_Error (Loc,
6452 Make_Attribute_Reference (Loc,
6454 Attribute_Name => Name_Valid)),
6455 Reason => CE_Invalid_Data);
6457 -- Insert the validity check. Note that we do this with validity
6458 -- checks turned off, to avoid recursion, we do not want validity
6459 -- checks on the validity checking code itself!
6461 Insert_Action (Expr, CE, Suppress => Validity_Check);
6463 -- If the expression is a reference to an element of a bit-packed
6464 -- array, then it is rewritten as a renaming declaration. If the
6465 -- expression is an actual in a call, it has not been expanded,
6466 -- waiting for the proper point at which to do it. The same happens
6467 -- with renamings, so that we have to force the expansion now. This
6468 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
6471 if Is_Entity_Name (Exp)
6472 and then Nkind (Parent (Entity (Exp))) =
6473 N_Object_Renaming_Declaration
6476 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
6478 if Nkind (Old_Exp) = N_Indexed_Component
6479 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
6481 Expand_Packed_Element_Reference (Old_Exp);
6486 -- Put back the Do_Range_Check flag on the resulting (possibly
6487 -- rewritten) expression.
6489 -- Note: it might be thought that a validity check is not required
6490 -- when a range check is present, but that's not the case, because
6491 -- the back end is allowed to assume for the range check that the
6492 -- operand is within its declared range (an assumption that validity
6493 -- checking is all about NOT assuming!)
6495 -- Note: no need to worry about Possible_Local_Raise here, it will
6496 -- already have been called if original node has Do_Range_Check set.
6498 Set_Do_Range_Check (Exp, DRC);
6500 end Insert_Valid_Check;
6502 -------------------------------------
6503 -- Is_Signed_Integer_Arithmetic_Op --
6504 -------------------------------------
6506 function Is_Signed_Integer_Arithmetic_Op (N : Node_Id) return Boolean is
6509 when N_Op_Abs | N_Op_Add | N_Op_Divide | N_Op_Expon |
6510 N_Op_Minus | N_Op_Mod | N_Op_Multiply | N_Op_Plus |
6511 N_Op_Rem | N_Op_Subtract =>
6512 return Is_Signed_Integer_Type (Etype (N));
6514 when N_If_Expression | N_Case_Expression =>
6515 return Is_Signed_Integer_Type (Etype (N));
6520 end Is_Signed_Integer_Arithmetic_Op;
6522 ----------------------------------
6523 -- Install_Null_Excluding_Check --
6524 ----------------------------------
6526 procedure Install_Null_Excluding_Check (N : Node_Id) is
6527 Loc : constant Source_Ptr := Sloc (Parent (N));
6528 Typ : constant Entity_Id := Etype (N);
6530 function Safe_To_Capture_In_Parameter_Value return Boolean;
6531 -- Determines if it is safe to capture Known_Non_Null status for an
6532 -- the entity referenced by node N. The caller ensures that N is indeed
6533 -- an entity name. It is safe to capture the non-null status for an IN
6534 -- parameter when the reference occurs within a declaration that is sure
6535 -- to be executed as part of the declarative region.
6537 procedure Mark_Non_Null;
6538 -- After installation of check, if the node in question is an entity
6539 -- name, then mark this entity as non-null if possible.
6541 function Safe_To_Capture_In_Parameter_Value return Boolean is
6542 E : constant Entity_Id := Entity (N);
6543 S : constant Entity_Id := Current_Scope;
6547 if Ekind (E) /= E_In_Parameter then
6551 -- Two initial context checks. We must be inside a subprogram body
6552 -- with declarations and reference must not appear in nested scopes.
6554 if (Ekind (S) /= E_Function and then Ekind (S) /= E_Procedure)
6555 or else Scope (E) /= S
6560 S_Par := Parent (Parent (S));
6562 if Nkind (S_Par) /= N_Subprogram_Body
6563 or else No (Declarations (S_Par))
6573 -- Retrieve the declaration node of N (if any). Note that N
6574 -- may be a part of a complex initialization expression.
6578 while Present (P) loop
6580 -- If we have a short circuit form, and we are within the right
6581 -- hand expression, we return false, since the right hand side
6582 -- is not guaranteed to be elaborated.
6584 if Nkind (P) in N_Short_Circuit
6585 and then N = Right_Opnd (P)
6590 -- Similarly, if we are in an if expression and not part of the
6591 -- condition, then we return False, since neither the THEN or
6592 -- ELSE dependent expressions will always be elaborated.
6594 if Nkind (P) = N_If_Expression
6595 and then N /= First (Expressions (P))
6600 -- If we are in a case expression, and not part of the
6601 -- expression, then we return False, since a particular
6602 -- dependent expression may not always be elaborated
6604 if Nkind (P) = N_Case_Expression
6605 and then N /= Expression (P)
6610 -- While traversing the parent chain, we find that N
6611 -- belongs to a statement, thus it may never appear in
6612 -- a declarative region.
6614 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
6615 or else Nkind (P) = N_Procedure_Call_Statement
6620 -- If we are at a declaration, record it and exit
6622 if Nkind (P) in N_Declaration
6623 and then Nkind (P) not in N_Subprogram_Specification
6636 return List_Containing (N_Decl) = Declarations (S_Par);
6638 end Safe_To_Capture_In_Parameter_Value;
6644 procedure Mark_Non_Null is
6646 -- Only case of interest is if node N is an entity name
6648 if Is_Entity_Name (N) then
6650 -- For sure, we want to clear an indication that this is known to
6651 -- be null, since if we get past this check, it definitely is not!
6653 Set_Is_Known_Null (Entity (N), False);
6655 -- We can mark the entity as known to be non-null if either it is
6656 -- safe to capture the value, or in the case of an IN parameter,
6657 -- which is a constant, if the check we just installed is in the
6658 -- declarative region of the subprogram body. In this latter case,
6659 -- a check is decisive for the rest of the body if the expression
6660 -- is sure to be elaborated, since we know we have to elaborate
6661 -- all declarations before executing the body.
6663 -- Couldn't this always be part of Safe_To_Capture_Value ???
6665 if Safe_To_Capture_Value (N, Entity (N))
6666 or else Safe_To_Capture_In_Parameter_Value
6668 Set_Is_Known_Non_Null (Entity (N));
6673 -- Start of processing for Install_Null_Excluding_Check
6676 pragma Assert (Is_Access_Type (Typ));
6678 -- No check inside a generic (why not???)
6680 if Inside_A_Generic then
6684 -- No check needed if known to be non-null
6686 if Known_Non_Null (N) then
6690 -- If known to be null, here is where we generate a compile time check
6692 if Known_Null (N) then
6694 -- Avoid generating warning message inside init procs
6696 if not Inside_Init_Proc then
6697 Apply_Compile_Time_Constraint_Error
6699 "null value not allowed here??",
6700 CE_Access_Check_Failed);
6703 Make_Raise_Constraint_Error (Loc,
6704 Reason => CE_Access_Check_Failed));
6711 -- If entity is never assigned, for sure a warning is appropriate
6713 if Is_Entity_Name (N) then
6714 Check_Unset_Reference (N);
6717 -- No check needed if checks are suppressed on the range. Note that we
6718 -- don't set Is_Known_Non_Null in this case (we could legitimately do
6719 -- so, since the program is erroneous, but we don't like to casually
6720 -- propagate such conclusions from erroneosity).
6722 if Access_Checks_Suppressed (Typ) then
6726 -- No check needed for access to concurrent record types generated by
6727 -- the expander. This is not just an optimization (though it does indeed
6728 -- remove junk checks). It also avoids generation of junk warnings.
6730 if Nkind (N) in N_Has_Chars
6731 and then Chars (N) = Name_uObject
6732 and then Is_Concurrent_Record_Type
6733 (Directly_Designated_Type (Etype (N)))
6738 -- No check needed in interface thunks since the runtime check is
6739 -- already performed at the caller side.
6741 if Is_Thunk (Current_Scope) then
6745 -- No check needed for the Get_Current_Excep.all.all idiom generated by
6746 -- the expander within exception handlers, since we know that the value
6747 -- can never be null.
6749 -- Is this really the right way to do this? Normally we generate such
6750 -- code in the expander with checks off, and that's how we suppress this
6751 -- kind of junk check ???
6753 if Nkind (N) = N_Function_Call
6754 and then Nkind (Name (N)) = N_Explicit_Dereference
6755 and then Nkind (Prefix (Name (N))) = N_Identifier
6756 and then Is_RTE (Entity (Prefix (Name (N))), RE_Get_Current_Excep)
6761 -- Otherwise install access check
6764 Make_Raise_Constraint_Error (Loc,
6767 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
6768 Right_Opnd => Make_Null (Loc)),
6769 Reason => CE_Access_Check_Failed));
6772 end Install_Null_Excluding_Check;
6774 --------------------------
6775 -- Install_Static_Check --
6776 --------------------------
6778 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
6779 Stat : constant Boolean := Is_Static_Expression (R_Cno);
6780 Typ : constant Entity_Id := Etype (R_Cno);
6784 Make_Raise_Constraint_Error (Loc,
6785 Reason => CE_Range_Check_Failed));
6786 Set_Analyzed (R_Cno);
6787 Set_Etype (R_Cno, Typ);
6788 Set_Raises_Constraint_Error (R_Cno);
6789 Set_Is_Static_Expression (R_Cno, Stat);
6791 -- Now deal with possible local raise handling
6793 Possible_Local_Raise (R_Cno, Standard_Constraint_Error);
6794 end Install_Static_Check;
6796 -------------------------
6797 -- Is_Check_Suppressed --
6798 -------------------------
6800 function Is_Check_Suppressed (E : Entity_Id; C : Check_Id) return Boolean is
6801 Ptr : Suppress_Stack_Entry_Ptr;
6804 -- First search the local entity suppress stack. We search this from the
6805 -- top of the stack down so that we get the innermost entry that applies
6806 -- to this case if there are nested entries.
6808 Ptr := Local_Suppress_Stack_Top;
6809 while Ptr /= null loop
6810 if (Ptr.Entity = Empty or else Ptr.Entity = E)
6811 and then (Ptr.Check = All_Checks or else Ptr.Check = C)
6813 return Ptr.Suppress;
6819 -- Now search the global entity suppress table for a matching entry.
6820 -- We also search this from the top down so that if there are multiple
6821 -- pragmas for the same entity, the last one applies (not clear what
6822 -- or whether the RM specifies this handling, but it seems reasonable).
6824 Ptr := Global_Suppress_Stack_Top;
6825 while Ptr /= null loop
6826 if (Ptr.Entity = Empty or else Ptr.Entity = E)
6827 and then (Ptr.Check = All_Checks or else Ptr.Check = C)
6829 return Ptr.Suppress;
6835 -- If we did not find a matching entry, then use the normal scope
6836 -- suppress value after all (actually this will be the global setting
6837 -- since it clearly was not overridden at any point). For a predefined
6838 -- check, we test the specific flag. For a user defined check, we check
6839 -- the All_Checks flag. The Overflow flag requires special handling to
6840 -- deal with the General vs Assertion case
6842 if C = Overflow_Check then
6843 return Overflow_Checks_Suppressed (Empty);
6844 elsif C in Predefined_Check_Id then
6845 return Scope_Suppress.Suppress (C);
6847 return Scope_Suppress.Suppress (All_Checks);
6849 end Is_Check_Suppressed;
6851 ---------------------
6852 -- Kill_All_Checks --
6853 ---------------------
6855 procedure Kill_All_Checks is
6857 if Debug_Flag_CC then
6858 w ("Kill_All_Checks");
6861 -- We reset the number of saved checks to zero, and also modify all
6862 -- stack entries for statement ranges to indicate that the number of
6863 -- checks at each level is now zero.
6865 Num_Saved_Checks := 0;
6867 -- Note: the Int'Min here avoids any possibility of J being out of
6868 -- range when called from e.g. Conditional_Statements_Begin.
6870 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
6871 Saved_Checks_Stack (J) := 0;
6873 end Kill_All_Checks;
6879 procedure Kill_Checks (V : Entity_Id) is
6881 if Debug_Flag_CC then
6882 w ("Kill_Checks for entity", Int (V));
6885 for J in 1 .. Num_Saved_Checks loop
6886 if Saved_Checks (J).Entity = V then
6887 if Debug_Flag_CC then
6888 w (" Checks killed for saved check ", J);
6891 Saved_Checks (J).Killed := True;
6896 ------------------------------
6897 -- Length_Checks_Suppressed --
6898 ------------------------------
6900 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
6902 if Present (E) and then Checks_May_Be_Suppressed (E) then
6903 return Is_Check_Suppressed (E, Length_Check);
6905 return Scope_Suppress.Suppress (Length_Check);
6907 end Length_Checks_Suppressed;
6909 -----------------------
6910 -- Make_Bignum_Block --
6911 -----------------------
6913 function Make_Bignum_Block (Loc : Source_Ptr) return Node_Id is
6914 M : constant Entity_Id := Make_Defining_Identifier (Loc, Name_uM);
6918 Make_Block_Statement (Loc,
6919 Declarations => New_List (
6920 Make_Object_Declaration (Loc,
6921 Defining_Identifier => M,
6922 Object_Definition =>
6923 New_Occurrence_Of (RTE (RE_Mark_Id), Loc),
6925 Make_Function_Call (Loc,
6926 Name => New_Reference_To (RTE (RE_SS_Mark), Loc)))),
6928 Handled_Statement_Sequence =>
6929 Make_Handled_Sequence_Of_Statements (Loc,
6930 Statements => New_List (
6931 Make_Procedure_Call_Statement (Loc,
6932 Name => New_Occurrence_Of (RTE (RE_SS_Release), Loc),
6933 Parameter_Associations => New_List (
6934 New_Reference_To (M, Loc))))));
6935 end Make_Bignum_Block;
6937 ----------------------------------
6938 -- Minimize_Eliminate_Overflows --
6939 ----------------------------------
6941 -- This is a recursive routine that is called at the top of an expression
6942 -- tree to properly process overflow checking for a whole subtree by making
6943 -- recursive calls to process operands. This processing may involve the use
6944 -- of bignum or long long integer arithmetic, which will change the types
6945 -- of operands and results. That's why we can't do this bottom up (since
6946 -- it would interfere with semantic analysis).
6948 -- What happens is that if MINIMIZED/ELIMINATED mode is in effect then
6949 -- the operator expansion routines, as well as the expansion routines for
6950 -- if/case expression, do nothing (for the moment) except call the routine
6951 -- to apply the overflow check (Apply_Arithmetic_Overflow_Check). That
6952 -- routine does nothing for non top-level nodes, so at the point where the
6953 -- call is made for the top level node, the entire expression subtree has
6954 -- not been expanded, or processed for overflow. All that has to happen as
6955 -- a result of the top level call to this routine.
6957 -- As noted above, the overflow processing works by making recursive calls
6958 -- for the operands, and figuring out what to do, based on the processing
6959 -- of these operands (e.g. if a bignum operand appears, the parent op has
6960 -- to be done in bignum mode), and the determined ranges of the operands.
6962 -- After possible rewriting of a constituent subexpression node, a call is
6963 -- made to either reexpand the node (if nothing has changed) or reanalyze
6964 -- the node (if it has been modified by the overflow check processing). The
6965 -- Analyzed_Flag is set to False before the reexpand/reanalyze. To avoid
6966 -- a recursive call into the whole overflow apparatus, an important rule
6967 -- for this call is that the overflow handling mode must be temporarily set
6970 procedure Minimize_Eliminate_Overflows
6974 Top_Level : Boolean)
6976 Rtyp : constant Entity_Id := Etype (N);
6977 pragma Assert (Is_Signed_Integer_Type (Rtyp));
6978 -- Result type, must be a signed integer type
6980 Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
6981 pragma Assert (Check_Mode in Minimized_Or_Eliminated);
6983 Loc : constant Source_Ptr := Sloc (N);
6986 -- Ranges of values for right operand (operator case)
6989 -- Ranges of values for left operand (operator case)
6991 LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer);
6992 -- Operands and results are of this type when we convert
6994 LLLo : constant Uint := Intval (Type_Low_Bound (LLIB));
6995 LLHi : constant Uint := Intval (Type_High_Bound (LLIB));
6996 -- Bounds of Long_Long_Integer
6998 Binary : constant Boolean := Nkind (N) in N_Binary_Op;
6999 -- Indicates binary operator case
7002 -- Used in call to Determine_Range
7004 Bignum_Operands : Boolean;
7005 -- Set True if one or more operands is already of type Bignum, meaning
7006 -- that for sure (regardless of Top_Level setting) we are committed to
7007 -- doing the operation in Bignum mode (or in the case of a case or if
7008 -- expression, converting all the dependent expressions to Bignum).
7010 Long_Long_Integer_Operands : Boolean;
7011 -- Set True if one or more operands is already of type Long_Long_Integer
7012 -- which means that if the result is known to be in the result type
7013 -- range, then we must convert such operands back to the result type.
7015 procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False);
7016 -- This is called when we have modified the node and we therefore need
7017 -- to reanalyze it. It is important that we reset the mode to STRICT for
7018 -- this reanalysis, since if we leave it in MINIMIZED or ELIMINATED mode
7019 -- we would reenter this routine recursively which would not be good!
7020 -- The argument Suppress is set True if we also want to suppress
7021 -- overflow checking for the reexpansion (this is set when we know
7022 -- overflow is not possible). Typ is the type for the reanalysis.
7024 procedure Reexpand (Suppress : Boolean := False);
7025 -- This is like Reanalyze, but does not do the Analyze step, it only
7026 -- does a reexpansion. We do this reexpansion in STRICT mode, so that
7027 -- instead of reentering the MINIMIZED/ELIMINATED mode processing, we
7028 -- follow the normal expansion path (e.g. converting A**4 to A**2**2).
7029 -- Note that skipping reanalysis is not just an optimization, testing
7030 -- has showed up several complex cases in which reanalyzing an already
7031 -- analyzed node causes incorrect behavior.
7033 function In_Result_Range return Boolean;
7034 -- Returns True iff Lo .. Hi are within range of the result type
7036 procedure Max (A : in out Uint; B : Uint);
7037 -- If A is No_Uint, sets A to B, else to UI_Max (A, B)
7039 procedure Min (A : in out Uint; B : Uint);
7040 -- If A is No_Uint, sets A to B, else to UI_Min (A, B)
7042 ---------------------
7043 -- In_Result_Range --
7044 ---------------------
7046 function In_Result_Range return Boolean is
7048 if Lo = No_Uint or else Hi = No_Uint then
7051 elsif Is_Static_Subtype (Etype (N)) then
7052 return Lo >= Expr_Value (Type_Low_Bound (Rtyp))
7054 Hi <= Expr_Value (Type_High_Bound (Rtyp));
7057 return Lo >= Expr_Value (Type_Low_Bound (Base_Type (Rtyp)))
7059 Hi <= Expr_Value (Type_High_Bound (Base_Type (Rtyp)));
7061 end In_Result_Range;
7067 procedure Max (A : in out Uint; B : Uint) is
7069 if A = No_Uint or else B > A then
7078 procedure Min (A : in out Uint; B : Uint) is
7080 if A = No_Uint or else B < A then
7089 procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False) is
7090 Svg : constant Overflow_Mode_Type :=
7091 Scope_Suppress.Overflow_Mode_General;
7092 Sva : constant Overflow_Mode_Type :=
7093 Scope_Suppress.Overflow_Mode_Assertions;
7094 Svo : constant Boolean :=
7095 Scope_Suppress.Suppress (Overflow_Check);
7098 Scope_Suppress.Overflow_Mode_General := Strict;
7099 Scope_Suppress.Overflow_Mode_Assertions := Strict;
7102 Scope_Suppress.Suppress (Overflow_Check) := True;
7105 Analyze_And_Resolve (N, Typ);
7107 Scope_Suppress.Suppress (Overflow_Check) := Svo;
7108 Scope_Suppress.Overflow_Mode_General := Svg;
7109 Scope_Suppress.Overflow_Mode_Assertions := Sva;
7116 procedure Reexpand (Suppress : Boolean := False) is
7117 Svg : constant Overflow_Mode_Type :=
7118 Scope_Suppress.Overflow_Mode_General;
7119 Sva : constant Overflow_Mode_Type :=
7120 Scope_Suppress.Overflow_Mode_Assertions;
7121 Svo : constant Boolean :=
7122 Scope_Suppress.Suppress (Overflow_Check);
7125 Scope_Suppress.Overflow_Mode_General := Strict;
7126 Scope_Suppress.Overflow_Mode_Assertions := Strict;
7127 Set_Analyzed (N, False);
7130 Scope_Suppress.Suppress (Overflow_Check) := True;
7135 Scope_Suppress.Suppress (Overflow_Check) := Svo;
7136 Scope_Suppress.Overflow_Mode_General := Svg;
7137 Scope_Suppress.Overflow_Mode_Assertions := Sva;
7140 -- Start of processing for Minimize_Eliminate_Overflows
7143 -- Case where we do not have a signed integer arithmetic operation
7145 if not Is_Signed_Integer_Arithmetic_Op (N) then
7147 -- Use the normal Determine_Range routine to get the range. We
7148 -- don't require operands to be valid, invalid values may result in
7149 -- rubbish results where the result has not been properly checked for
7150 -- overflow, that's fine!
7152 Determine_Range (N, OK, Lo, Hi, Assume_Valid => False);
7154 -- If Determine_Range did not work (can this in fact happen? Not
7155 -- clear but might as well protect), use type bounds.
7158 Lo := Intval (Type_Low_Bound (Base_Type (Etype (N))));
7159 Hi := Intval (Type_High_Bound (Base_Type (Etype (N))));
7162 -- If we don't have a binary operator, all we have to do is to set
7163 -- the Hi/Lo range, so we are done
7167 -- Processing for if expression
7169 elsif Nkind (N) = N_If_Expression then
7171 Then_DE : constant Node_Id := Next (First (Expressions (N)));
7172 Else_DE : constant Node_Id := Next (Then_DE);
7175 Bignum_Operands := False;
7177 Minimize_Eliminate_Overflows
7178 (Then_DE, Lo, Hi, Top_Level => False);
7180 if Lo = No_Uint then
7181 Bignum_Operands := True;
7184 Minimize_Eliminate_Overflows
7185 (Else_DE, Rlo, Rhi, Top_Level => False);
7187 if Rlo = No_Uint then
7188 Bignum_Operands := True;
7190 Long_Long_Integer_Operands :=
7191 Etype (Then_DE) = LLIB or else Etype (Else_DE) = LLIB;
7197 -- If at least one of our operands is now Bignum, we must rebuild
7198 -- the if expression to use Bignum operands. We will analyze the
7199 -- rebuilt if expression with overflow checks off, since once we
7200 -- are in bignum mode, we are all done with overflow checks!
7202 if Bignum_Operands then
7204 Make_If_Expression (Loc,
7205 Expressions => New_List (
7206 Remove_Head (Expressions (N)),
7207 Convert_To_Bignum (Then_DE),
7208 Convert_To_Bignum (Else_DE)),
7209 Is_Elsif => Is_Elsif (N)));
7211 Reanalyze (RTE (RE_Bignum), Suppress => True);
7213 -- If we have no Long_Long_Integer operands, then we are in result
7214 -- range, since it means that none of our operands felt the need
7215 -- to worry about overflow (otherwise it would have already been
7216 -- converted to long long integer or bignum). We reexpand to
7217 -- complete the expansion of the if expression (but we do not
7218 -- need to reanalyze).
7220 elsif not Long_Long_Integer_Operands then
7221 Set_Do_Overflow_Check (N, False);
7224 -- Otherwise convert us to long long integer mode. Note that we
7225 -- don't need any further overflow checking at this level.
7228 Convert_To_And_Rewrite (LLIB, Then_DE);
7229 Convert_To_And_Rewrite (LLIB, Else_DE);
7230 Set_Etype (N, LLIB);
7232 -- Now reanalyze with overflow checks off
7234 Set_Do_Overflow_Check (N, False);
7235 Reanalyze (LLIB, Suppress => True);
7241 -- Here for case expression
7243 elsif Nkind (N) = N_Case_Expression then
7244 Bignum_Operands := False;
7245 Long_Long_Integer_Operands := False;
7251 -- Loop through expressions applying recursive call
7253 Alt := First (Alternatives (N));
7254 while Present (Alt) loop
7256 Aexp : constant Node_Id := Expression (Alt);
7259 Minimize_Eliminate_Overflows
7260 (Aexp, Lo, Hi, Top_Level => False);
7262 if Lo = No_Uint then
7263 Bignum_Operands := True;
7264 elsif Etype (Aexp) = LLIB then
7265 Long_Long_Integer_Operands := True;
7272 -- If we have no bignum or long long integer operands, it means
7273 -- that none of our dependent expressions could raise overflow.
7274 -- In this case, we simply return with no changes except for
7275 -- resetting the overflow flag, since we are done with overflow
7276 -- checks for this node. We will reexpand to get the needed
7277 -- expansion for the case expression, but we do not need to
7278 -- reanalyze, since nothing has changed.
7280 if not (Bignum_Operands or Long_Long_Integer_Operands) then
7281 Set_Do_Overflow_Check (N, False);
7282 Reexpand (Suppress => True);
7284 -- Otherwise we are going to rebuild the case expression using
7285 -- either bignum or long long integer operands throughout.
7294 New_Alts := New_List;
7295 Alt := First (Alternatives (N));
7296 while Present (Alt) loop
7297 if Bignum_Operands then
7298 New_Exp := Convert_To_Bignum (Expression (Alt));
7299 Rtype := RTE (RE_Bignum);
7301 New_Exp := Convert_To (LLIB, Expression (Alt));
7305 Append_To (New_Alts,
7306 Make_Case_Expression_Alternative (Sloc (Alt),
7308 Discrete_Choices => Discrete_Choices (Alt),
7309 Expression => New_Exp));
7315 Make_Case_Expression (Loc,
7316 Expression => Expression (N),
7317 Alternatives => New_Alts));
7319 Reanalyze (Rtype, Suppress => True);
7327 -- If we have an arithmetic operator we make recursive calls on the
7328 -- operands to get the ranges (and to properly process the subtree
7329 -- that lies below us!)
7331 Minimize_Eliminate_Overflows
7332 (Right_Opnd (N), Rlo, Rhi, Top_Level => False);
7335 Minimize_Eliminate_Overflows
7336 (Left_Opnd (N), Llo, Lhi, Top_Level => False);
7339 -- Record if we have Long_Long_Integer operands
7341 Long_Long_Integer_Operands :=
7342 Etype (Right_Opnd (N)) = LLIB
7343 or else (Binary and then Etype (Left_Opnd (N)) = LLIB);
7345 -- If either operand is a bignum, then result will be a bignum and we
7346 -- don't need to do any range analysis. As previously discussed we could
7347 -- do range analysis in such cases, but it could mean working with giant
7348 -- numbers at compile time for very little gain (the number of cases
7349 -- in which we could slip back from bignum mode is small).
7351 if Rlo = No_Uint or else (Binary and then Llo = No_Uint) then
7354 Bignum_Operands := True;
7356 -- Otherwise compute result range
7359 Bignum_Operands := False;
7367 Hi := UI_Max (abs Rlo, abs Rhi);
7379 -- If the right operand can only be zero, set 0..0
7381 if Rlo = 0 and then Rhi = 0 then
7385 -- Possible bounds of division must come from dividing end
7386 -- values of the input ranges (four possibilities), provided
7387 -- zero is not included in the possible values of the right
7390 -- Otherwise, we just consider two intervals of values for
7391 -- the right operand: the interval of negative values (up to
7392 -- -1) and the interval of positive values (starting at 1).
7393 -- Since division by 1 is the identity, and division by -1
7394 -- is negation, we get all possible bounds of division in that
7395 -- case by considering:
7396 -- - all values from the division of end values of input
7398 -- - the end values of the left operand;
7399 -- - the negation of the end values of the left operand.
7403 Mrk : constant Uintp.Save_Mark := Mark;
7404 -- Mark so we can release the RR and Ev values
7412 -- Discard extreme values of zero for the divisor, since
7413 -- they will simply result in an exception in any case.
7421 -- Compute possible bounds coming from dividing end
7422 -- values of the input ranges.
7429 Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4));
7430 Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4));
7432 -- If the right operand can be both negative or positive,
7433 -- include the end values of the left operand in the
7434 -- extreme values, as well as their negation.
7436 if Rlo < 0 and then Rhi > 0 then
7443 UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4)));
7445 UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4)));
7448 -- Release the RR and Ev values
7450 Release_And_Save (Mrk, Lo, Hi);
7458 -- Discard negative values for the exponent, since they will
7459 -- simply result in an exception in any case.
7467 -- Estimate number of bits in result before we go computing
7468 -- giant useless bounds. Basically the number of bits in the
7469 -- result is the number of bits in the base multiplied by the
7470 -- value of the exponent. If this is big enough that the result
7471 -- definitely won't fit in Long_Long_Integer, switch to bignum
7472 -- mode immediately, and avoid computing giant bounds.
7474 -- The comparison here is approximate, but conservative, it
7475 -- only clicks on cases that are sure to exceed the bounds.
7477 if Num_Bits (UI_Max (abs Llo, abs Lhi)) * Rhi + 1 > 100 then
7481 -- If right operand is zero then result is 1
7488 -- High bound comes either from exponentiation of largest
7489 -- positive value to largest exponent value, or from
7490 -- the exponentiation of most negative value to an
7504 if Rhi mod 2 = 0 then
7507 Hi2 := Llo ** (Rhi - 1);
7513 Hi := UI_Max (Hi1, Hi2);
7516 -- Result can only be negative if base can be negative
7519 if Rhi mod 2 = 0 then
7520 Lo := Llo ** (Rhi - 1);
7525 -- Otherwise low bound is minimum ** minimum
7542 Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1;
7543 -- This is the maximum absolute value of the result
7549 -- The result depends only on the sign and magnitude of
7550 -- the right operand, it does not depend on the sign or
7551 -- magnitude of the left operand.
7564 when N_Op_Multiply =>
7566 -- Possible bounds of multiplication must come from multiplying
7567 -- end values of the input ranges (four possibilities).
7570 Mrk : constant Uintp.Save_Mark := Mark;
7571 -- Mark so we can release the Ev values
7573 Ev1 : constant Uint := Llo * Rlo;
7574 Ev2 : constant Uint := Llo * Rhi;
7575 Ev3 : constant Uint := Lhi * Rlo;
7576 Ev4 : constant Uint := Lhi * Rhi;
7579 Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4));
7580 Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4));
7582 -- Release the Ev values
7584 Release_And_Save (Mrk, Lo, Hi);
7587 -- Plus operator (affirmation)
7597 Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1;
7598 -- This is the maximum absolute value of the result. Note
7599 -- that the result range does not depend on the sign of the
7606 -- Case of left operand negative, which results in a range
7607 -- of -Maxabs .. 0 for those negative values. If there are
7608 -- no negative values then Lo value of result is always 0.
7614 -- Case of left operand positive
7623 when N_Op_Subtract =>
7627 -- Nothing else should be possible
7630 raise Program_Error;
7634 -- Here for the case where we have not rewritten anything (no bignum
7635 -- operands or long long integer operands), and we know the result.
7636 -- If we know we are in the result range, and we do not have Bignum
7637 -- operands or Long_Long_Integer operands, we can just reexpand with
7638 -- overflow checks turned off (since we know we cannot have overflow).
7639 -- As always the reexpansion is required to complete expansion of the
7640 -- operator, but we do not need to reanalyze, and we prevent recursion
7641 -- by suppressing the check.
7643 if not (Bignum_Operands or Long_Long_Integer_Operands)
7644 and then In_Result_Range
7646 Set_Do_Overflow_Check (N, False);
7647 Reexpand (Suppress => True);
7650 -- Here we know that we are not in the result range, and in the general
7651 -- case we will move into either the Bignum or Long_Long_Integer domain
7652 -- to compute the result. However, there is one exception. If we are
7653 -- at the top level, and we do not have Bignum or Long_Long_Integer
7654 -- operands, we will have to immediately convert the result back to
7655 -- the result type, so there is no point in Bignum/Long_Long_Integer
7659 and then not (Bignum_Operands or Long_Long_Integer_Operands)
7661 -- One further refinement. If we are at the top level, but our parent
7662 -- is a type conversion, then go into bignum or long long integer node
7663 -- since the result will be converted to that type directly without
7664 -- going through the result type, and we may avoid an overflow. This
7665 -- is the case for example of Long_Long_Integer (A ** 4), where A is
7666 -- of type Integer, and the result A ** 4 fits in Long_Long_Integer
7667 -- but does not fit in Integer.
7669 and then Nkind (Parent (N)) /= N_Type_Conversion
7671 -- Here keep original types, but we need to complete analysis
7673 -- One subtlety. We can't just go ahead and do an analyze operation
7674 -- here because it will cause recursion into the whole MINIMIZED/
7675 -- ELIMINATED overflow processing which is not what we want. Here
7676 -- we are at the top level, and we need a check against the result
7677 -- mode (i.e. we want to use STRICT mode). So do exactly that!
7678 -- Also, we have not modified the node, so this is a case where
7679 -- we need to reexpand, but not reanalyze.
7684 -- Cases where we do the operation in Bignum mode. This happens either
7685 -- because one of our operands is in Bignum mode already, or because
7686 -- the computed bounds are outside the bounds of Long_Long_Integer,
7687 -- which in some cases can be indicated by Hi and Lo being No_Uint.
7689 -- Note: we could do better here and in some cases switch back from
7690 -- Bignum mode to normal mode, e.g. big mod 2 must be in the range
7691 -- 0 .. 1, but the cases are rare and it is not worth the effort.
7692 -- Failing to do this switching back is only an efficiency issue.
7694 elsif Lo = No_Uint or else Lo < LLLo or else Hi > LLHi then
7696 -- OK, we are definitely outside the range of Long_Long_Integer. The
7697 -- question is whether to move to Bignum mode, or stay in the domain
7698 -- of Long_Long_Integer, signalling that an overflow check is needed.
7700 -- Obviously in MINIMIZED mode we stay with LLI, since we are not in
7701 -- the Bignum business. In ELIMINATED mode, we will normally move
7702 -- into Bignum mode, but there is an exception if neither of our
7703 -- operands is Bignum now, and we are at the top level (Top_Level
7704 -- set True). In this case, there is no point in moving into Bignum
7705 -- mode to prevent overflow if the caller will immediately convert
7706 -- the Bignum value back to LLI with an overflow check. It's more
7707 -- efficient to stay in LLI mode with an overflow check (if needed)
7709 if Check_Mode = Minimized
7710 or else (Top_Level and not Bignum_Operands)
7712 if Do_Overflow_Check (N) then
7713 Enable_Overflow_Check (N);
7716 -- The result now has to be in Long_Long_Integer mode, so adjust
7717 -- the possible range to reflect this. Note these calls also
7718 -- change No_Uint values from the top level case to LLI bounds.
7723 -- Otherwise we are in ELIMINATED mode and we switch to Bignum mode
7726 pragma Assert (Check_Mode = Eliminated);
7735 Fent := RTE (RE_Big_Abs);
7738 Fent := RTE (RE_Big_Add);
7741 Fent := RTE (RE_Big_Div);
7744 Fent := RTE (RE_Big_Exp);
7747 Fent := RTE (RE_Big_Neg);
7750 Fent := RTE (RE_Big_Mod);
7752 when N_Op_Multiply =>
7753 Fent := RTE (RE_Big_Mul);
7756 Fent := RTE (RE_Big_Rem);
7758 when N_Op_Subtract =>
7759 Fent := RTE (RE_Big_Sub);
7761 -- Anything else is an internal error, this includes the
7762 -- N_Op_Plus case, since how can plus cause the result
7763 -- to be out of range if the operand is in range?
7766 raise Program_Error;
7769 -- Construct argument list for Bignum call, converting our
7770 -- operands to Bignum form if they are not already there.
7775 Append_To (Args, Convert_To_Bignum (Left_Opnd (N)));
7778 Append_To (Args, Convert_To_Bignum (Right_Opnd (N)));
7780 -- Now rewrite the arithmetic operator with a call to the
7781 -- corresponding bignum function.
7784 Make_Function_Call (Loc,
7785 Name => New_Occurrence_Of (Fent, Loc),
7786 Parameter_Associations => Args));
7787 Reanalyze (RTE (RE_Bignum), Suppress => True);
7789 -- Indicate result is Bignum mode
7797 -- Otherwise we are in range of Long_Long_Integer, so no overflow
7798 -- check is required, at least not yet.
7801 Set_Do_Overflow_Check (N, False);
7804 -- Here we are not in Bignum territory, but we may have long long
7805 -- integer operands that need special handling. First a special check:
7806 -- If an exponentiation operator exponent is of type Long_Long_Integer,
7807 -- it means we converted it to prevent overflow, but exponentiation
7808 -- requires a Natural right operand, so convert it back to Natural.
7809 -- This conversion may raise an exception which is fine.
7811 if Nkind (N) = N_Op_Expon and then Etype (Right_Opnd (N)) = LLIB then
7812 Convert_To_And_Rewrite (Standard_Natural, Right_Opnd (N));
7815 -- Here we will do the operation in Long_Long_Integer. We do this even
7816 -- if we know an overflow check is required, better to do this in long
7817 -- long integer mode, since we are less likely to overflow!
7819 -- Convert right or only operand to Long_Long_Integer, except that
7820 -- we do not touch the exponentiation right operand.
7822 if Nkind (N) /= N_Op_Expon then
7823 Convert_To_And_Rewrite (LLIB, Right_Opnd (N));
7826 -- Convert left operand to Long_Long_Integer for binary case
7829 Convert_To_And_Rewrite (LLIB, Left_Opnd (N));
7832 -- Reset node to unanalyzed
7834 Set_Analyzed (N, False);
7835 Set_Etype (N, Empty);
7836 Set_Entity (N, Empty);
7838 -- Now analyze this new node. This reanalysis will complete processing
7839 -- for the node. In particular we will complete the expansion of an
7840 -- exponentiation operator (e.g. changing A ** 2 to A * A), and also
7841 -- we will complete any division checks (since we have not changed the
7842 -- setting of the Do_Division_Check flag).
7844 -- We do this reanalysis in STRICT mode to avoid recursion into the
7845 -- MINIMIZED/ELIMINATED handling, since we are now done with that!
7848 SG : constant Overflow_Mode_Type :=
7849 Scope_Suppress.Overflow_Mode_General;
7850 SA : constant Overflow_Mode_Type :=
7851 Scope_Suppress.Overflow_Mode_Assertions;
7854 Scope_Suppress.Overflow_Mode_General := Strict;
7855 Scope_Suppress.Overflow_Mode_Assertions := Strict;
7857 if not Do_Overflow_Check (N) then
7858 Reanalyze (LLIB, Suppress => True);
7863 Scope_Suppress.Overflow_Mode_General := SG;
7864 Scope_Suppress.Overflow_Mode_Assertions := SA;
7866 end Minimize_Eliminate_Overflows;
7868 -------------------------
7869 -- Overflow_Check_Mode --
7870 -------------------------
7872 function Overflow_Check_Mode return Overflow_Mode_Type is
7874 if In_Assertion_Expr = 0 then
7875 return Scope_Suppress.Overflow_Mode_General;
7877 return Scope_Suppress.Overflow_Mode_Assertions;
7879 end Overflow_Check_Mode;
7881 --------------------------------
7882 -- Overflow_Checks_Suppressed --
7883 --------------------------------
7885 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
7887 if Present (E) and then Checks_May_Be_Suppressed (E) then
7888 return Is_Check_Suppressed (E, Overflow_Check);
7890 return Scope_Suppress.Suppress (Overflow_Check);
7892 end Overflow_Checks_Suppressed;
7894 ---------------------------------
7895 -- Predicate_Checks_Suppressed --
7896 ---------------------------------
7898 function Predicate_Checks_Suppressed (E : Entity_Id) return Boolean is
7900 if Present (E) and then Checks_May_Be_Suppressed (E) then
7901 return Is_Check_Suppressed (E, Predicate_Check);
7903 return Scope_Suppress.Suppress (Predicate_Check);
7905 end Predicate_Checks_Suppressed;
7907 -----------------------------
7908 -- Range_Checks_Suppressed --
7909 -----------------------------
7911 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
7915 -- Note: for now we always suppress range checks on Vax float types,
7916 -- since Gigi does not know how to generate these checks.
7918 if Vax_Float (E) then
7920 elsif Kill_Range_Checks (E) then
7922 elsif Checks_May_Be_Suppressed (E) then
7923 return Is_Check_Suppressed (E, Range_Check);
7927 return Scope_Suppress.Suppress (Range_Check);
7928 end Range_Checks_Suppressed;
7930 -----------------------------------------
7931 -- Range_Or_Validity_Checks_Suppressed --
7932 -----------------------------------------
7934 -- Note: the coding would be simpler here if we simply made appropriate
7935 -- calls to Range/Validity_Checks_Suppressed, but that would result in
7936 -- duplicated checks which we prefer to avoid.
7938 function Range_Or_Validity_Checks_Suppressed
7939 (Expr : Node_Id) return Boolean
7942 -- Immediate return if scope checks suppressed for either check
7944 if Scope_Suppress.Suppress (Range_Check)
7946 Scope_Suppress.Suppress (Validity_Check)
7951 -- If no expression, that's odd, decide that checks are suppressed,
7952 -- since we don't want anyone trying to do checks in this case, which
7953 -- is most likely the result of some other error.
7959 -- Expression is present, so perform suppress checks on type
7962 Typ : constant Entity_Id := Etype (Expr);
7964 if Vax_Float (Typ) then
7966 elsif Checks_May_Be_Suppressed (Typ)
7967 and then (Is_Check_Suppressed (Typ, Range_Check)
7969 Is_Check_Suppressed (Typ, Validity_Check))
7975 -- If expression is an entity name, perform checks on this entity
7977 if Is_Entity_Name (Expr) then
7979 Ent : constant Entity_Id := Entity (Expr);
7981 if Checks_May_Be_Suppressed (Ent) then
7982 return Is_Check_Suppressed (Ent, Range_Check)
7983 or else Is_Check_Suppressed (Ent, Validity_Check);
7988 -- If we fall through, no checks suppressed
7991 end Range_Or_Validity_Checks_Suppressed;
7997 procedure Remove_Checks (Expr : Node_Id) is
7998 function Process (N : Node_Id) return Traverse_Result;
7999 -- Process a single node during the traversal
8001 procedure Traverse is new Traverse_Proc (Process);
8002 -- The traversal procedure itself
8008 function Process (N : Node_Id) return Traverse_Result is
8010 if Nkind (N) not in N_Subexpr then
8014 Set_Do_Range_Check (N, False);
8018 Traverse (Left_Opnd (N));
8021 when N_Attribute_Reference =>
8022 Set_Do_Overflow_Check (N, False);
8024 when N_Function_Call =>
8025 Set_Do_Tag_Check (N, False);
8028 Set_Do_Overflow_Check (N, False);
8032 Set_Do_Division_Check (N, False);
8035 Set_Do_Length_Check (N, False);
8038 Set_Do_Division_Check (N, False);
8041 Set_Do_Length_Check (N, False);
8044 Set_Do_Division_Check (N, False);
8047 Set_Do_Length_Check (N, False);
8054 Traverse (Left_Opnd (N));
8057 when N_Selected_Component =>
8058 Set_Do_Discriminant_Check (N, False);
8060 when N_Type_Conversion =>
8061 Set_Do_Length_Check (N, False);
8062 Set_Do_Tag_Check (N, False);
8063 Set_Do_Overflow_Check (N, False);
8072 -- Start of processing for Remove_Checks
8078 ----------------------------
8079 -- Selected_Length_Checks --
8080 ----------------------------
8082 function Selected_Length_Checks
8084 Target_Typ : Entity_Id;
8085 Source_Typ : Entity_Id;
8086 Warn_Node : Node_Id) return Check_Result
8088 Loc : constant Source_Ptr := Sloc (Ck_Node);
8091 Expr_Actual : Node_Id;
8093 Cond : Node_Id := Empty;
8094 Do_Access : Boolean := False;
8095 Wnode : Node_Id := Warn_Node;
8096 Ret_Result : Check_Result := (Empty, Empty);
8097 Num_Checks : Natural := 0;
8099 procedure Add_Check (N : Node_Id);
8100 -- Adds the action given to Ret_Result if N is non-Empty
8102 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
8103 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
8104 -- Comments required ???
8106 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
8107 -- True for equal literals and for nodes that denote the same constant
8108 -- entity, even if its value is not a static constant. This includes the
8109 -- case of a discriminal reference within an init proc. Removes some
8110 -- obviously superfluous checks.
8112 function Length_E_Cond
8113 (Exptyp : Entity_Id;
8115 Indx : Nat) return Node_Id;
8116 -- Returns expression to compute:
8117 -- Typ'Length /= Exptyp'Length
8119 function Length_N_Cond
8122 Indx : Nat) return Node_Id;
8123 -- Returns expression to compute:
8124 -- Typ'Length /= Expr'Length
8130 procedure Add_Check (N : Node_Id) is
8134 -- For now, ignore attempt to place more than 2 checks ???
8136 if Num_Checks = 2 then
8140 pragma Assert (Num_Checks <= 1);
8141 Num_Checks := Num_Checks + 1;
8142 Ret_Result (Num_Checks) := N;
8150 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
8151 SE : constant Entity_Id := Scope (E);
8153 E1 : Entity_Id := E;
8156 if Ekind (Scope (E)) = E_Record_Type
8157 and then Has_Discriminants (Scope (E))
8159 N := Build_Discriminal_Subtype_Of_Component (E);
8162 Insert_Action (Ck_Node, N);
8163 E1 := Defining_Identifier (N);
8167 if Ekind (E1) = E_String_Literal_Subtype then
8169 Make_Integer_Literal (Loc,
8170 Intval => String_Literal_Length (E1));
8172 elsif SE /= Standard_Standard
8173 and then Ekind (Scope (SE)) = E_Protected_Type
8174 and then Has_Discriminants (Scope (SE))
8175 and then Has_Completion (Scope (SE))
8176 and then not Inside_Init_Proc
8178 -- If the type whose length is needed is a private component
8179 -- constrained by a discriminant, we must expand the 'Length
8180 -- attribute into an explicit computation, using the discriminal
8181 -- of the current protected operation. This is because the actual
8182 -- type of the prival is constructed after the protected opera-
8183 -- tion has been fully expanded.
8186 Indx_Type : Node_Id;
8189 Do_Expand : Boolean := False;
8192 Indx_Type := First_Index (E);
8194 for J in 1 .. Indx - 1 loop
8195 Next_Index (Indx_Type);
8198 Get_Index_Bounds (Indx_Type, Lo, Hi);
8200 if Nkind (Lo) = N_Identifier
8201 and then Ekind (Entity (Lo)) = E_In_Parameter
8203 Lo := Get_Discriminal (E, Lo);
8207 if Nkind (Hi) = N_Identifier
8208 and then Ekind (Entity (Hi)) = E_In_Parameter
8210 Hi := Get_Discriminal (E, Hi);
8215 if not Is_Entity_Name (Lo) then
8216 Lo := Duplicate_Subexpr_No_Checks (Lo);
8219 if not Is_Entity_Name (Hi) then
8220 Lo := Duplicate_Subexpr_No_Checks (Hi);
8226 Make_Op_Subtract (Loc,
8230 Right_Opnd => Make_Integer_Literal (Loc, 1));
8235 Make_Attribute_Reference (Loc,
8236 Attribute_Name => Name_Length,
8238 New_Occurrence_Of (E1, Loc));
8241 Set_Expressions (N, New_List (
8242 Make_Integer_Literal (Loc, Indx)));
8251 Make_Attribute_Reference (Loc,
8252 Attribute_Name => Name_Length,
8254 New_Occurrence_Of (E1, Loc));
8257 Set_Expressions (N, New_List (
8258 Make_Integer_Literal (Loc, Indx)));
8269 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
8272 Make_Attribute_Reference (Loc,
8273 Attribute_Name => Name_Length,
8275 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
8276 Expressions => New_List (
8277 Make_Integer_Literal (Loc, Indx)));
8284 function Length_E_Cond
8285 (Exptyp : Entity_Id;
8287 Indx : Nat) return Node_Id
8292 Left_Opnd => Get_E_Length (Typ, Indx),
8293 Right_Opnd => Get_E_Length (Exptyp, Indx));
8300 function Length_N_Cond
8303 Indx : Nat) return Node_Id
8308 Left_Opnd => Get_E_Length (Typ, Indx),
8309 Right_Opnd => Get_N_Length (Expr, Indx));
8316 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
8319 (Nkind (L) = N_Integer_Literal
8320 and then Nkind (R) = N_Integer_Literal
8321 and then Intval (L) = Intval (R))
8325 and then Ekind (Entity (L)) = E_Constant
8326 and then ((Is_Entity_Name (R)
8327 and then Entity (L) = Entity (R))
8329 (Nkind (R) = N_Type_Conversion
8330 and then Is_Entity_Name (Expression (R))
8331 and then Entity (L) = Entity (Expression (R)))))
8335 and then Ekind (Entity (R)) = E_Constant
8336 and then Nkind (L) = N_Type_Conversion
8337 and then Is_Entity_Name (Expression (L))
8338 and then Entity (R) = Entity (Expression (L)))
8342 and then Is_Entity_Name (R)
8343 and then Entity (L) = Entity (R)
8344 and then Ekind (Entity (L)) = E_In_Parameter
8345 and then Inside_Init_Proc);
8348 -- Start of processing for Selected_Length_Checks
8351 if not Expander_Active then
8355 if Target_Typ = Any_Type
8356 or else Target_Typ = Any_Composite
8357 or else Raises_Constraint_Error (Ck_Node)
8366 T_Typ := Target_Typ;
8368 if No (Source_Typ) then
8369 S_Typ := Etype (Ck_Node);
8371 S_Typ := Source_Typ;
8374 if S_Typ = Any_Type or else S_Typ = Any_Composite then
8378 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
8379 S_Typ := Designated_Type (S_Typ);
8380 T_Typ := Designated_Type (T_Typ);
8383 -- A simple optimization for the null case
8385 if Known_Null (Ck_Node) then
8390 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
8391 if Is_Constrained (T_Typ) then
8393 -- The checking code to be generated will freeze the corresponding
8394 -- array type. However, we must freeze the type now, so that the
8395 -- freeze node does not appear within the generated if expression,
8398 Freeze_Before (Ck_Node, T_Typ);
8400 Expr_Actual := Get_Referenced_Object (Ck_Node);
8401 Exptyp := Get_Actual_Subtype (Ck_Node);
8403 if Is_Access_Type (Exptyp) then
8404 Exptyp := Designated_Type (Exptyp);
8407 -- String_Literal case. This needs to be handled specially be-
8408 -- cause no index types are available for string literals. The
8409 -- condition is simply:
8411 -- T_Typ'Length = string-literal-length
8413 if Nkind (Expr_Actual) = N_String_Literal
8414 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
8418 Left_Opnd => Get_E_Length (T_Typ, 1),
8420 Make_Integer_Literal (Loc,
8422 String_Literal_Length (Etype (Expr_Actual))));
8424 -- General array case. Here we have a usable actual subtype for
8425 -- the expression, and the condition is built from the two types
8428 -- T_Typ'Length /= Exptyp'Length or else
8429 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
8430 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
8433 elsif Is_Constrained (Exptyp) then
8435 Ndims : constant Nat := Number_Dimensions (T_Typ);
8448 -- At the library level, we need to ensure that the type of
8449 -- the object is elaborated before the check itself is
8450 -- emitted. This is only done if the object is in the
8451 -- current compilation unit, otherwise the type is frozen
8452 -- and elaborated in its unit.
8454 if Is_Itype (Exptyp)
8456 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
8458 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
8459 and then In_Open_Scopes (Scope (Exptyp))
8461 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
8462 Set_Itype (Ref_Node, Exptyp);
8463 Insert_Action (Ck_Node, Ref_Node);
8466 L_Index := First_Index (T_Typ);
8467 R_Index := First_Index (Exptyp);
8469 for Indx in 1 .. Ndims loop
8470 if not (Nkind (L_Index) = N_Raise_Constraint_Error
8472 Nkind (R_Index) = N_Raise_Constraint_Error)
8474 Get_Index_Bounds (L_Index, L_Low, L_High);
8475 Get_Index_Bounds (R_Index, R_Low, R_High);
8477 -- Deal with compile time length check. Note that we
8478 -- skip this in the access case, because the access
8479 -- value may be null, so we cannot know statically.
8482 and then Compile_Time_Known_Value (L_Low)
8483 and then Compile_Time_Known_Value (L_High)
8484 and then Compile_Time_Known_Value (R_Low)
8485 and then Compile_Time_Known_Value (R_High)
8487 if Expr_Value (L_High) >= Expr_Value (L_Low) then
8488 L_Length := Expr_Value (L_High) -
8489 Expr_Value (L_Low) + 1;
8491 L_Length := UI_From_Int (0);
8494 if Expr_Value (R_High) >= Expr_Value (R_Low) then
8495 R_Length := Expr_Value (R_High) -
8496 Expr_Value (R_Low) + 1;
8498 R_Length := UI_From_Int (0);
8501 if L_Length > R_Length then
8503 (Compile_Time_Constraint_Error
8504 (Wnode, "too few elements for}??", T_Typ));
8506 elsif L_Length < R_Length then
8508 (Compile_Time_Constraint_Error
8509 (Wnode, "too many elements for}??", T_Typ));
8512 -- The comparison for an individual index subtype
8513 -- is omitted if the corresponding index subtypes
8514 -- statically match, since the result is known to
8515 -- be true. Note that this test is worth while even
8516 -- though we do static evaluation, because non-static
8517 -- subtypes can statically match.
8520 Subtypes_Statically_Match
8521 (Etype (L_Index), Etype (R_Index))
8524 (Same_Bounds (L_Low, R_Low)
8525 and then Same_Bounds (L_High, R_High))
8528 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
8537 -- Handle cases where we do not get a usable actual subtype that
8538 -- is constrained. This happens for example in the function call
8539 -- and explicit dereference cases. In these cases, we have to get
8540 -- the length or range from the expression itself, making sure we
8541 -- do not evaluate it more than once.
8543 -- Here Ck_Node is the original expression, or more properly the
8544 -- result of applying Duplicate_Expr to the original tree, forcing
8545 -- the result to be a name.
8549 Ndims : constant Nat := Number_Dimensions (T_Typ);
8552 -- Build the condition for the explicit dereference case
8554 for Indx in 1 .. Ndims loop
8556 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
8563 -- Construct the test and insert into the tree
8565 if Present (Cond) then
8567 Cond := Guard_Access (Cond, Loc, Ck_Node);
8571 (Make_Raise_Constraint_Error (Loc,
8573 Reason => CE_Length_Check_Failed));
8577 end Selected_Length_Checks;
8579 ---------------------------
8580 -- Selected_Range_Checks --
8581 ---------------------------
8583 function Selected_Range_Checks
8585 Target_Typ : Entity_Id;
8586 Source_Typ : Entity_Id;
8587 Warn_Node : Node_Id) return Check_Result
8589 Loc : constant Source_Ptr := Sloc (Ck_Node);
8592 Expr_Actual : Node_Id;
8594 Cond : Node_Id := Empty;
8595 Do_Access : Boolean := False;
8596 Wnode : Node_Id := Warn_Node;
8597 Ret_Result : Check_Result := (Empty, Empty);
8598 Num_Checks : Integer := 0;
8600 procedure Add_Check (N : Node_Id);
8601 -- Adds the action given to Ret_Result if N is non-Empty
8603 function Discrete_Range_Cond
8605 Typ : Entity_Id) return Node_Id;
8606 -- Returns expression to compute:
8607 -- Low_Bound (Expr) < Typ'First
8609 -- High_Bound (Expr) > Typ'Last
8611 function Discrete_Expr_Cond
8613 Typ : Entity_Id) return Node_Id;
8614 -- Returns expression to compute:
8619 function Get_E_First_Or_Last
8623 Nam : Name_Id) return Node_Id;
8624 -- Returns an attribute reference
8625 -- E'First or E'Last
8626 -- with a source location of Loc.
8628 -- Nam is Name_First or Name_Last, according to which attribute is
8629 -- desired. If Indx is non-zero, it is passed as a literal in the
8630 -- Expressions of the attribute reference (identifying the desired
8631 -- array dimension).
8633 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
8634 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
8635 -- Returns expression to compute:
8636 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
8638 function Range_E_Cond
8639 (Exptyp : Entity_Id;
8643 -- Returns expression to compute:
8644 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
8646 function Range_Equal_E_Cond
8647 (Exptyp : Entity_Id;
8649 Indx : Nat) return Node_Id;
8650 -- Returns expression to compute:
8651 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
8653 function Range_N_Cond
8656 Indx : Nat) return Node_Id;
8657 -- Return expression to compute:
8658 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
8664 procedure Add_Check (N : Node_Id) is
8668 -- For now, ignore attempt to place more than 2 checks ???
8670 if Num_Checks = 2 then
8674 pragma Assert (Num_Checks <= 1);
8675 Num_Checks := Num_Checks + 1;
8676 Ret_Result (Num_Checks) := N;
8680 -------------------------
8681 -- Discrete_Expr_Cond --
8682 -------------------------
8684 function Discrete_Expr_Cond
8686 Typ : Entity_Id) return Node_Id
8694 Convert_To (Base_Type (Typ),
8695 Duplicate_Subexpr_No_Checks (Expr)),
8697 Convert_To (Base_Type (Typ),
8698 Get_E_First_Or_Last (Loc, Typ, 0, Name_First))),
8703 Convert_To (Base_Type (Typ),
8704 Duplicate_Subexpr_No_Checks (Expr)),
8708 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last))));
8709 end Discrete_Expr_Cond;
8711 -------------------------
8712 -- Discrete_Range_Cond --
8713 -------------------------
8715 function Discrete_Range_Cond
8717 Typ : Entity_Id) return Node_Id
8719 LB : Node_Id := Low_Bound (Expr);
8720 HB : Node_Id := High_Bound (Expr);
8722 Left_Opnd : Node_Id;
8723 Right_Opnd : Node_Id;
8726 if Nkind (LB) = N_Identifier
8727 and then Ekind (Entity (LB)) = E_Discriminant
8729 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
8736 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
8741 Get_E_First_Or_Last (Loc, Typ, 0, Name_First)));
8743 if Nkind (HB) = N_Identifier
8744 and then Ekind (Entity (HB)) = E_Discriminant
8746 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
8753 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
8758 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last)));
8760 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
8761 end Discrete_Range_Cond;
8763 -------------------------
8764 -- Get_E_First_Or_Last --
8765 -------------------------
8767 function Get_E_First_Or_Last
8771 Nam : Name_Id) return Node_Id
8776 Exprs := New_List (Make_Integer_Literal (Loc, UI_From_Int (Indx)));
8781 return Make_Attribute_Reference (Loc,
8782 Prefix => New_Occurrence_Of (E, Loc),
8783 Attribute_Name => Nam,
8784 Expressions => Exprs);
8785 end Get_E_First_Or_Last;
8791 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
8794 Make_Attribute_Reference (Loc,
8795 Attribute_Name => Name_First,
8797 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
8798 Expressions => New_List (
8799 Make_Integer_Literal (Loc, Indx)));
8806 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
8809 Make_Attribute_Reference (Loc,
8810 Attribute_Name => Name_Last,
8812 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
8813 Expressions => New_List (
8814 Make_Integer_Literal (Loc, Indx)));
8821 function Range_E_Cond
8822 (Exptyp : Entity_Id;
8824 Indx : Nat) return Node_Id
8832 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
8834 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
8839 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
8841 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
8844 ------------------------
8845 -- Range_Equal_E_Cond --
8846 ------------------------
8848 function Range_Equal_E_Cond
8849 (Exptyp : Entity_Id;
8851 Indx : Nat) return Node_Id
8859 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
8861 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
8866 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
8868 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
8869 end Range_Equal_E_Cond;
8875 function Range_N_Cond
8878 Indx : Nat) return Node_Id
8886 Get_N_First (Expr, Indx),
8888 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
8893 Get_N_Last (Expr, Indx),
8895 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
8898 -- Start of processing for Selected_Range_Checks
8901 if not Expander_Active then
8905 if Target_Typ = Any_Type
8906 or else Target_Typ = Any_Composite
8907 or else Raises_Constraint_Error (Ck_Node)
8916 T_Typ := Target_Typ;
8918 if No (Source_Typ) then
8919 S_Typ := Etype (Ck_Node);
8921 S_Typ := Source_Typ;
8924 if S_Typ = Any_Type or else S_Typ = Any_Composite then
8928 -- The order of evaluating T_Typ before S_Typ seems to be critical
8929 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
8930 -- in, and since Node can be an N_Range node, it might be invalid.
8931 -- Should there be an assert check somewhere for taking the Etype of
8932 -- an N_Range node ???
8934 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
8935 S_Typ := Designated_Type (S_Typ);
8936 T_Typ := Designated_Type (T_Typ);
8939 -- A simple optimization for the null case
8941 if Known_Null (Ck_Node) then
8946 -- For an N_Range Node, check for a null range and then if not
8947 -- null generate a range check action.
8949 if Nkind (Ck_Node) = N_Range then
8951 -- There's no point in checking a range against itself
8953 if Ck_Node = Scalar_Range (T_Typ) then
8958 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
8959 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
8960 Known_T_LB : constant Boolean := Compile_Time_Known_Value (T_LB);
8961 Known_T_HB : constant Boolean := Compile_Time_Known_Value (T_HB);
8963 LB : Node_Id := Low_Bound (Ck_Node);
8964 HB : Node_Id := High_Bound (Ck_Node);
8968 Null_Range : Boolean;
8969 Out_Of_Range_L : Boolean;
8970 Out_Of_Range_H : Boolean;
8973 -- Compute what is known at compile time
8975 if Known_T_LB and Known_T_HB then
8976 if Compile_Time_Known_Value (LB) then
8979 -- There's no point in checking that a bound is within its
8980 -- own range so pretend that it is known in this case. First
8981 -- deal with low bound.
8983 elsif Ekind (Etype (LB)) = E_Signed_Integer_Subtype
8984 and then Scalar_Range (Etype (LB)) = Scalar_Range (T_Typ)
8993 -- Likewise for the high bound
8995 if Compile_Time_Known_Value (HB) then
8998 elsif Ekind (Etype (HB)) = E_Signed_Integer_Subtype
8999 and then Scalar_Range (Etype (HB)) = Scalar_Range (T_Typ)
9009 -- Check for case where everything is static and we can do the
9010 -- check at compile time. This is skipped if we have an access
9011 -- type, since the access value may be null.
9013 -- ??? This code can be improved since you only need to know that
9014 -- the two respective bounds (LB & T_LB or HB & T_HB) are known at
9015 -- compile time to emit pertinent messages.
9017 if Known_T_LB and Known_T_HB and Known_LB and Known_HB
9020 -- Floating-point case
9022 if Is_Floating_Point_Type (S_Typ) then
9023 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
9025 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
9027 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
9030 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
9032 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
9034 -- Fixed or discrete type case
9037 Null_Range := Expr_Value (HB) < Expr_Value (LB);
9039 (Expr_Value (LB) < Expr_Value (T_LB))
9041 (Expr_Value (LB) > Expr_Value (T_HB));
9044 (Expr_Value (HB) > Expr_Value (T_HB))
9046 (Expr_Value (HB) < Expr_Value (T_LB));
9049 if not Null_Range then
9050 if Out_Of_Range_L then
9051 if No (Warn_Node) then
9053 (Compile_Time_Constraint_Error
9054 (Low_Bound (Ck_Node),
9055 "static value out of range of}??", T_Typ));
9059 (Compile_Time_Constraint_Error
9061 "static range out of bounds of}??", T_Typ));
9065 if Out_Of_Range_H then
9066 if No (Warn_Node) then
9068 (Compile_Time_Constraint_Error
9069 (High_Bound (Ck_Node),
9070 "static value out of range of}??", T_Typ));
9074 (Compile_Time_Constraint_Error
9076 "static range out of bounds of}??", T_Typ));
9083 LB : Node_Id := Low_Bound (Ck_Node);
9084 HB : Node_Id := High_Bound (Ck_Node);
9087 -- If either bound is a discriminant and we are within the
9088 -- record declaration, it is a use of the discriminant in a
9089 -- constraint of a component, and nothing can be checked
9090 -- here. The check will be emitted within the init proc.
9091 -- Before then, the discriminal has no real meaning.
9092 -- Similarly, if the entity is a discriminal, there is no
9093 -- check to perform yet.
9095 -- The same holds within a discriminated synchronized type,
9096 -- where the discriminant may constrain a component or an
9099 if Nkind (LB) = N_Identifier
9100 and then Denotes_Discriminant (LB, True)
9102 if Current_Scope = Scope (Entity (LB))
9103 or else Is_Concurrent_Type (Current_Scope)
9104 or else Ekind (Entity (LB)) /= E_Discriminant
9109 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
9113 if Nkind (HB) = N_Identifier
9114 and then Denotes_Discriminant (HB, True)
9116 if Current_Scope = Scope (Entity (HB))
9117 or else Is_Concurrent_Type (Current_Scope)
9118 or else Ekind (Entity (HB)) /= E_Discriminant
9123 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
9127 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
9128 Set_Paren_Count (Cond, 1);
9134 Left_Opnd => Duplicate_Subexpr_No_Checks (HB),
9135 Right_Opnd => Duplicate_Subexpr_No_Checks (LB)),
9136 Right_Opnd => Cond);
9141 elsif Is_Scalar_Type (S_Typ) then
9143 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
9144 -- except the above simply sets a flag in the node and lets
9145 -- gigi generate the check base on the Etype of the expression.
9146 -- Sometimes, however we want to do a dynamic check against an
9147 -- arbitrary target type, so we do that here.
9149 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
9150 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9152 -- For literals, we can tell if the constraint error will be
9153 -- raised at compile time, so we never need a dynamic check, but
9154 -- if the exception will be raised, then post the usual warning,
9155 -- and replace the literal with a raise constraint error
9156 -- expression. As usual, skip this for access types
9158 elsif Compile_Time_Known_Value (Ck_Node)
9159 and then not Do_Access
9162 LB : constant Node_Id := Type_Low_Bound (T_Typ);
9163 UB : constant Node_Id := Type_High_Bound (T_Typ);
9165 Out_Of_Range : Boolean;
9166 Static_Bounds : constant Boolean :=
9167 Compile_Time_Known_Value (LB)
9168 and Compile_Time_Known_Value (UB);
9171 -- Following range tests should use Sem_Eval routine ???
9173 if Static_Bounds then
9174 if Is_Floating_Point_Type (S_Typ) then
9176 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
9178 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
9180 -- Fixed or discrete type
9184 Expr_Value (Ck_Node) < Expr_Value (LB)
9186 Expr_Value (Ck_Node) > Expr_Value (UB);
9189 -- Bounds of the type are static and the literal is out of
9190 -- range so output a warning message.
9192 if Out_Of_Range then
9193 if No (Warn_Node) then
9195 (Compile_Time_Constraint_Error
9197 "static value out of range of}??", T_Typ));
9201 (Compile_Time_Constraint_Error
9203 "static value out of range of}??", T_Typ));
9208 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9212 -- Here for the case of a non-static expression, we need a runtime
9213 -- check unless the source type range is guaranteed to be in the
9214 -- range of the target type.
9217 if not In_Subrange_Of (S_Typ, T_Typ) then
9218 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9223 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
9224 if Is_Constrained (T_Typ) then
9226 Expr_Actual := Get_Referenced_Object (Ck_Node);
9227 Exptyp := Get_Actual_Subtype (Expr_Actual);
9229 if Is_Access_Type (Exptyp) then
9230 Exptyp := Designated_Type (Exptyp);
9233 -- String_Literal case. This needs to be handled specially be-
9234 -- cause no index types are available for string literals. The
9235 -- condition is simply:
9237 -- T_Typ'Length = string-literal-length
9239 if Nkind (Expr_Actual) = N_String_Literal then
9242 -- General array case. Here we have a usable actual subtype for
9243 -- the expression, and the condition is built from the two types
9245 -- T_Typ'First < Exptyp'First or else
9246 -- T_Typ'Last > Exptyp'Last or else
9247 -- T_Typ'First(1) < Exptyp'First(1) or else
9248 -- T_Typ'Last(1) > Exptyp'Last(1) or else
9251 elsif Is_Constrained (Exptyp) then
9253 Ndims : constant Nat := Number_Dimensions (T_Typ);
9259 L_Index := First_Index (T_Typ);
9260 R_Index := First_Index (Exptyp);
9262 for Indx in 1 .. Ndims loop
9263 if not (Nkind (L_Index) = N_Raise_Constraint_Error
9265 Nkind (R_Index) = N_Raise_Constraint_Error)
9267 -- Deal with compile time length check. Note that we
9268 -- skip this in the access case, because the access
9269 -- value may be null, so we cannot know statically.
9272 Subtypes_Statically_Match
9273 (Etype (L_Index), Etype (R_Index))
9275 -- If the target type is constrained then we
9276 -- have to check for exact equality of bounds
9277 -- (required for qualified expressions).
9279 if Is_Constrained (T_Typ) then
9282 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
9285 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
9295 -- Handle cases where we do not get a usable actual subtype that
9296 -- is constrained. This happens for example in the function call
9297 -- and explicit dereference cases. In these cases, we have to get
9298 -- the length or range from the expression itself, making sure we
9299 -- do not evaluate it more than once.
9301 -- Here Ck_Node is the original expression, or more properly the
9302 -- result of applying Duplicate_Expr to the original tree,
9303 -- forcing the result to be a name.
9307 Ndims : constant Nat := Number_Dimensions (T_Typ);
9310 -- Build the condition for the explicit dereference case
9312 for Indx in 1 .. Ndims loop
9314 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
9320 -- For a conversion to an unconstrained array type, generate an
9321 -- Action to check that the bounds of the source value are within
9322 -- the constraints imposed by the target type (RM 4.6(38)). No
9323 -- check is needed for a conversion to an access to unconstrained
9324 -- array type, as 4.6(24.15/2) requires the designated subtypes
9325 -- of the two access types to statically match.
9327 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
9328 and then not Do_Access
9331 Opnd_Index : Node_Id;
9332 Targ_Index : Node_Id;
9333 Opnd_Range : Node_Id;
9336 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
9337 Targ_Index := First_Index (T_Typ);
9338 while Present (Opnd_Index) loop
9340 -- If the index is a range, use its bounds. If it is an
9341 -- entity (as will be the case if it is a named subtype
9342 -- or an itype created for a slice) retrieve its range.
9344 if Is_Entity_Name (Opnd_Index)
9345 and then Is_Type (Entity (Opnd_Index))
9347 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
9349 Opnd_Range := Opnd_Index;
9352 if Nkind (Opnd_Range) = N_Range then
9354 (Low_Bound (Opnd_Range), Etype (Targ_Index),
9355 Assume_Valid => True)
9358 (High_Bound (Opnd_Range), Etype (Targ_Index),
9359 Assume_Valid => True)
9363 -- If null range, no check needed
9366 Compile_Time_Known_Value (High_Bound (Opnd_Range))
9368 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
9370 Expr_Value (High_Bound (Opnd_Range)) <
9371 Expr_Value (Low_Bound (Opnd_Range))
9375 elsif Is_Out_Of_Range
9376 (Low_Bound (Opnd_Range), Etype (Targ_Index),
9377 Assume_Valid => True)
9380 (High_Bound (Opnd_Range), Etype (Targ_Index),
9381 Assume_Valid => True)
9384 (Compile_Time_Constraint_Error
9385 (Wnode, "value out of range of}??", T_Typ));
9391 (Opnd_Range, Etype (Targ_Index)));
9395 Next_Index (Opnd_Index);
9396 Next_Index (Targ_Index);
9403 -- Construct the test and insert into the tree
9405 if Present (Cond) then
9407 Cond := Guard_Access (Cond, Loc, Ck_Node);
9411 (Make_Raise_Constraint_Error (Loc,
9413 Reason => CE_Range_Check_Failed));
9417 end Selected_Range_Checks;
9419 -------------------------------
9420 -- Storage_Checks_Suppressed --
9421 -------------------------------
9423 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
9425 if Present (E) and then Checks_May_Be_Suppressed (E) then
9426 return Is_Check_Suppressed (E, Storage_Check);
9428 return Scope_Suppress.Suppress (Storage_Check);
9430 end Storage_Checks_Suppressed;
9432 ---------------------------
9433 -- Tag_Checks_Suppressed --
9434 ---------------------------
9436 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
9439 and then Checks_May_Be_Suppressed (E)
9441 return Is_Check_Suppressed (E, Tag_Check);
9444 return Scope_Suppress.Suppress (Tag_Check);
9445 end Tag_Checks_Suppressed;
9447 --------------------------
9448 -- Validity_Check_Range --
9449 --------------------------
9451 procedure Validity_Check_Range (N : Node_Id) is
9453 if Validity_Checks_On and Validity_Check_Operands then
9454 if Nkind (N) = N_Range then
9455 Ensure_Valid (Low_Bound (N));
9456 Ensure_Valid (High_Bound (N));
9459 end Validity_Check_Range;
9461 --------------------------------
9462 -- Validity_Checks_Suppressed --
9463 --------------------------------
9465 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
9467 if Present (E) and then Checks_May_Be_Suppressed (E) then
9468 return Is_Check_Suppressed (E, Validity_Check);
9470 return Scope_Suppress.Suppress (Validity_Check);
9472 end Validity_Checks_Suppressed;