1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Casing; use Casing;
28 with Debug; use Debug;
29 with Einfo; use Einfo;
30 with Elists; use Elists;
31 with Eval_Fat; use Eval_Fat;
32 with Exp_Ch11; use Exp_Ch11;
33 with Exp_Ch2; use Exp_Ch2;
34 with Exp_Ch4; use Exp_Ch4;
35 with Exp_Pakd; use Exp_Pakd;
36 with Exp_Util; use Exp_Util;
37 with Expander; use Expander;
38 with Freeze; use Freeze;
40 with Nlists; use Nlists;
41 with Nmake; use Nmake;
43 with Output; use Output;
44 with Restrict; use Restrict;
45 with Rident; use Rident;
46 with Rtsfind; use Rtsfind;
48 with Sem_Aux; use Sem_Aux;
49 with Sem_Ch3; use Sem_Ch3;
50 with Sem_Ch8; use Sem_Ch8;
51 with Sem_Eval; use Sem_Eval;
52 with Sem_Res; use Sem_Res;
53 with Sem_Util; use Sem_Util;
54 with Sem_Warn; use Sem_Warn;
55 with Sinfo; use Sinfo;
56 with Sinput; use Sinput;
57 with Snames; use Snames;
58 with Sprint; use Sprint;
59 with Stand; use Stand;
60 with Stringt; use Stringt;
61 with Targparm; use Targparm;
62 with Tbuild; use Tbuild;
63 with Ttypes; use Ttypes;
64 with Urealp; use Urealp;
65 with Validsw; use Validsw;
67 package body Checks is
69 -- General note: many of these routines are concerned with generating
70 -- checking code to make sure that constraint error is raised at runtime.
71 -- Clearly this code is only needed if the expander is active, since
72 -- otherwise we will not be generating code or going into the runtime
75 -- We therefore disconnect most of these checks if the expander is
76 -- inactive. This has the additional benefit that we do not need to
77 -- worry about the tree being messed up by previous errors (since errors
78 -- turn off expansion anyway).
80 -- There are a few exceptions to the above rule. For instance routines
81 -- such as Apply_Scalar_Range_Check that do not insert any code can be
82 -- safely called even when the Expander is inactive (but Errors_Detected
83 -- is 0). The benefit of executing this code when expansion is off, is
84 -- the ability to emit constraint error warning for static expressions
85 -- even when we are not generating code.
87 -- The above is modified in gnatprove mode to ensure that proper check
88 -- flags are always placed, even if expansion is off.
90 -------------------------------------
91 -- Suppression of Redundant Checks --
92 -------------------------------------
94 -- This unit implements a limited circuit for removal of redundant
95 -- checks. The processing is based on a tracing of simple sequential
96 -- flow. For any sequence of statements, we save expressions that are
97 -- marked to be checked, and then if the same expression appears later
98 -- with the same check, then under certain circumstances, the second
99 -- check can be suppressed.
101 -- Basically, we can suppress the check if we know for certain that
102 -- the previous expression has been elaborated (together with its
103 -- check), and we know that the exception frame is the same, and that
104 -- nothing has happened to change the result of the exception.
106 -- Let us examine each of these three conditions in turn to describe
107 -- how we ensure that this condition is met.
109 -- First, we need to know for certain that the previous expression has
110 -- been executed. This is done principally by the mechanism of calling
111 -- Conditional_Statements_Begin at the start of any statement sequence
112 -- and Conditional_Statements_End at the end. The End call causes all
113 -- checks remembered since the Begin call to be discarded. This does
114 -- miss a few cases, notably the case of a nested BEGIN-END block with
115 -- no exception handlers. But the important thing is to be conservative.
116 -- The other protection is that all checks are discarded if a label
117 -- is encountered, since then the assumption of sequential execution
118 -- is violated, and we don't know enough about the flow.
120 -- Second, we need to know that the exception frame is the same. We
121 -- do this by killing all remembered checks when we enter a new frame.
122 -- Again, that's over-conservative, but generally the cases we can help
123 -- with are pretty local anyway (like the body of a loop for example).
125 -- Third, we must be sure to forget any checks which are no longer valid.
126 -- This is done by two mechanisms, first the Kill_Checks_Variable call is
127 -- used to note any changes to local variables. We only attempt to deal
128 -- with checks involving local variables, so we do not need to worry
129 -- about global variables. Second, a call to any non-global procedure
130 -- causes us to abandon all stored checks, since such a all may affect
131 -- the values of any local variables.
133 -- The following define the data structures used to deal with remembering
134 -- checks so that redundant checks can be eliminated as described above.
136 -- Right now, the only expressions that we deal with are of the form of
137 -- simple local objects (either declared locally, or IN parameters) or
138 -- such objects plus/minus a compile time known constant. We can do
139 -- more later on if it seems worthwhile, but this catches many simple
140 -- cases in practice.
142 -- The following record type reflects a single saved check. An entry
143 -- is made in the stack of saved checks if and only if the expression
144 -- has been elaborated with the indicated checks.
146 type Saved_Check is record
148 -- Set True if entry is killed by Kill_Checks
151 -- The entity involved in the expression that is checked
154 -- A compile time value indicating the result of adding or
155 -- subtracting a compile time value. This value is to be
156 -- added to the value of the Entity. A value of zero is
157 -- used for the case of a simple entity reference.
159 Check_Type : Character;
160 -- This is set to 'R' for a range check (in which case Target_Type
161 -- is set to the target type for the range check) or to 'O' for an
162 -- overflow check (in which case Target_Type is set to Empty).
164 Target_Type : Entity_Id;
165 -- Used only if Do_Range_Check is set. Records the target type for
166 -- the check. We need this, because a check is a duplicate only if
167 -- it has the same target type (or more accurately one with a
168 -- range that is smaller or equal to the stored target type of a
172 -- The following table keeps track of saved checks. Rather than use an
173 -- extensible table. We just use a table of fixed size, and we discard
174 -- any saved checks that do not fit. That's very unlikely to happen and
175 -- this is only an optimization in any case.
177 Saved_Checks : array (Int range 1 .. 200) of Saved_Check;
178 -- Array of saved checks
180 Num_Saved_Checks : Nat := 0;
181 -- Number of saved checks
183 -- The following stack keeps track of statement ranges. It is treated
184 -- as a stack. When Conditional_Statements_Begin is called, an entry
185 -- is pushed onto this stack containing the value of Num_Saved_Checks
186 -- at the time of the call. Then when Conditional_Statements_End is
187 -- called, this value is popped off and used to reset Num_Saved_Checks.
189 -- Note: again, this is a fixed length stack with a size that should
190 -- always be fine. If the value of the stack pointer goes above the
191 -- limit, then we just forget all saved checks.
193 Saved_Checks_Stack : array (Int range 1 .. 100) of Nat;
194 Saved_Checks_TOS : Nat := 0;
196 -----------------------
197 -- Local Subprograms --
198 -----------------------
200 procedure Apply_Arithmetic_Overflow_Strict (N : Node_Id);
201 -- Used to apply arithmetic overflow checks for all cases except operators
202 -- on signed arithmetic types in MINIMIZED/ELIMINATED case (for which we
203 -- call Apply_Arithmetic_Overflow_Minimized_Eliminated below). N can be a
204 -- signed integer arithmetic operator (but not an if or case expression).
205 -- It is also called for types other than signed integers.
207 procedure Apply_Arithmetic_Overflow_Minimized_Eliminated (Op : Node_Id);
208 -- Used to apply arithmetic overflow checks for the case where the overflow
209 -- checking mode is MINIMIZED or ELIMINATED and we have a signed integer
210 -- arithmetic op (which includes the case of if and case expressions). Note
211 -- that Do_Overflow_Check may or may not be set for node Op. In these modes
212 -- we have work to do even if overflow checking is suppressed.
214 procedure Apply_Division_Check
219 -- N is an N_Op_Div, N_Op_Rem, or N_Op_Mod node. This routine applies
220 -- division checks as required if the Do_Division_Check flag is set.
221 -- Rlo and Rhi give the possible range of the right operand, these values
222 -- can be referenced and trusted only if ROK is set True.
224 procedure Apply_Float_Conversion_Check
226 Target_Typ : Entity_Id);
227 -- The checks on a conversion from a floating-point type to an integer
228 -- type are delicate. They have to be performed before conversion, they
229 -- have to raise an exception when the operand is a NaN, and rounding must
230 -- be taken into account to determine the safe bounds of the operand.
232 procedure Apply_Selected_Length_Checks
234 Target_Typ : Entity_Id;
235 Source_Typ : Entity_Id;
236 Do_Static : Boolean);
237 -- This is the subprogram that does all the work for Apply_Length_Check
238 -- and Apply_Static_Length_Check. Expr, Target_Typ and Source_Typ are as
239 -- described for the above routines. The Do_Static flag indicates that
240 -- only a static check is to be done.
242 procedure Apply_Selected_Range_Checks
244 Target_Typ : Entity_Id;
245 Source_Typ : Entity_Id;
246 Do_Static : Boolean);
247 -- This is the subprogram that does all the work for Apply_Range_Check.
248 -- Expr, Target_Typ and Source_Typ are as described for the above
249 -- routine. The Do_Static flag indicates that only a static check is
252 type Check_Type is new Check_Id range Access_Check .. Division_Check;
253 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean;
254 -- This function is used to see if an access or division by zero check is
255 -- needed. The check is to be applied to a single variable appearing in the
256 -- source, and N is the node for the reference. If N is not of this form,
257 -- True is returned with no further processing. If N is of the right form,
258 -- then further processing determines if the given Check is needed.
260 -- The particular circuit is to see if we have the case of a check that is
261 -- not needed because it appears in the right operand of a short circuited
262 -- conditional where the left operand guards the check. For example:
264 -- if Var = 0 or else Q / Var > 12 then
268 -- In this example, the division check is not required. At the same time
269 -- we can issue warnings for suspicious use of non-short-circuited forms,
272 -- if Var = 0 or Q / Var > 12 then
278 Check_Type : Character;
279 Target_Type : Entity_Id;
280 Entry_OK : out Boolean;
284 -- This routine is used by Enable_Range_Check and Enable_Overflow_Check
285 -- to see if a check is of the form for optimization, and if so, to see
286 -- if it has already been performed. Expr is the expression to check,
287 -- and Check_Type is 'R' for a range check, 'O' for an overflow check.
288 -- Target_Type is the target type for a range check, and Empty for an
289 -- overflow check. If the entry is not of the form for optimization,
290 -- then Entry_OK is set to False, and the remaining out parameters
291 -- are undefined. If the entry is OK, then Ent/Ofs are set to the
292 -- entity and offset from the expression. Check_Num is the number of
293 -- a matching saved entry in Saved_Checks, or zero if no such entry
296 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id;
297 -- If a discriminal is used in constraining a prival, Return reference
298 -- to the discriminal of the protected body (which renames the parameter
299 -- of the enclosing protected operation). This clumsy transformation is
300 -- needed because privals are created too late and their actual subtypes
301 -- are not available when analysing the bodies of the protected operations.
302 -- This function is called whenever the bound is an entity and the scope
303 -- indicates a protected operation. If the bound is an in-parameter of
304 -- a protected operation that is not a prival, the function returns the
306 -- To be cleaned up???
308 function Guard_Access
311 Ck_Node : Node_Id) return Node_Id;
312 -- In the access type case, guard the test with a test to ensure
313 -- that the access value is non-null, since the checks do not
314 -- not apply to null access values.
316 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr);
317 -- Called by Apply_{Length,Range}_Checks to rewrite the tree with the
318 -- Constraint_Error node.
320 function Is_Signed_Integer_Arithmetic_Op (N : Node_Id) return Boolean;
321 -- Returns True if node N is for an arithmetic operation with signed
322 -- integer operands. This includes unary and binary operators, and also
323 -- if and case expression nodes where the dependent expressions are of
324 -- a signed integer type. These are the kinds of nodes for which special
325 -- handling applies in MINIMIZED or ELIMINATED overflow checking mode.
327 function Range_Or_Validity_Checks_Suppressed
328 (Expr : Node_Id) return Boolean;
329 -- Returns True if either range or validity checks or both are suppressed
330 -- for the type of the given expression, or, if the expression is the name
331 -- of an entity, if these checks are suppressed for the entity.
333 function Selected_Length_Checks
335 Target_Typ : Entity_Id;
336 Source_Typ : Entity_Id;
337 Warn_Node : Node_Id) return Check_Result;
338 -- Like Apply_Selected_Length_Checks, except it doesn't modify
339 -- anything, just returns a list of nodes as described in the spec of
340 -- this package for the Range_Check function.
342 function Selected_Range_Checks
344 Target_Typ : Entity_Id;
345 Source_Typ : Entity_Id;
346 Warn_Node : Node_Id) return Check_Result;
347 -- Like Apply_Selected_Range_Checks, except it doesn't modify anything,
348 -- just returns a list of nodes as described in the spec of this package
349 -- for the Range_Check function.
351 ------------------------------
352 -- Access_Checks_Suppressed --
353 ------------------------------
355 function Access_Checks_Suppressed (E : Entity_Id) return Boolean is
357 if Present (E) and then Checks_May_Be_Suppressed (E) then
358 return Is_Check_Suppressed (E, Access_Check);
360 return Scope_Suppress.Suppress (Access_Check);
362 end Access_Checks_Suppressed;
364 -------------------------------------
365 -- Accessibility_Checks_Suppressed --
366 -------------------------------------
368 function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean is
370 if Present (E) and then Checks_May_Be_Suppressed (E) then
371 return Is_Check_Suppressed (E, Accessibility_Check);
373 return Scope_Suppress.Suppress (Accessibility_Check);
375 end Accessibility_Checks_Suppressed;
377 -----------------------------
378 -- Activate_Division_Check --
379 -----------------------------
381 procedure Activate_Division_Check (N : Node_Id) is
383 Set_Do_Division_Check (N, True);
384 Possible_Local_Raise (N, Standard_Constraint_Error);
385 end Activate_Division_Check;
387 -----------------------------
388 -- Activate_Overflow_Check --
389 -----------------------------
391 procedure Activate_Overflow_Check (N : Node_Id) is
393 if not Nkind_In (N, N_Op_Rem, N_Op_Mod, N_Op_Plus) then
394 Set_Do_Overflow_Check (N, True);
395 Possible_Local_Raise (N, Standard_Constraint_Error);
397 end Activate_Overflow_Check;
399 --------------------------
400 -- Activate_Range_Check --
401 --------------------------
403 procedure Activate_Range_Check (N : Node_Id) is
405 Set_Do_Range_Check (N, True);
406 Possible_Local_Raise (N, Standard_Constraint_Error);
407 end Activate_Range_Check;
409 ---------------------------------
410 -- Alignment_Checks_Suppressed --
411 ---------------------------------
413 function Alignment_Checks_Suppressed (E : Entity_Id) return Boolean is
415 if Present (E) and then Checks_May_Be_Suppressed (E) then
416 return Is_Check_Suppressed (E, Alignment_Check);
418 return Scope_Suppress.Suppress (Alignment_Check);
420 end Alignment_Checks_Suppressed;
422 ----------------------------------
423 -- Allocation_Checks_Suppressed --
424 ----------------------------------
426 -- Note: at the current time there are no calls to this function, because
427 -- the relevant check is in the run-time, so it is not a check that the
428 -- compiler can suppress anyway, but we still have to recognize the check
429 -- name Allocation_Check since it is part of the standard.
431 function Allocation_Checks_Suppressed (E : Entity_Id) return Boolean is
433 if Present (E) and then Checks_May_Be_Suppressed (E) then
434 return Is_Check_Suppressed (E, Allocation_Check);
436 return Scope_Suppress.Suppress (Allocation_Check);
438 end Allocation_Checks_Suppressed;
440 -------------------------
441 -- Append_Range_Checks --
442 -------------------------
444 procedure Append_Range_Checks
445 (Checks : Check_Result;
447 Suppress_Typ : Entity_Id;
448 Static_Sloc : Source_Ptr;
451 Internal_Flag_Node : constant Node_Id := Flag_Node;
452 Internal_Static_Sloc : constant Source_Ptr := Static_Sloc;
454 Checks_On : constant Boolean :=
455 (not Index_Checks_Suppressed (Suppress_Typ))
456 or else (not Range_Checks_Suppressed (Suppress_Typ));
459 -- For now we just return if Checks_On is false, however this should
460 -- be enhanced to check for an always True value in the condition
461 -- and to generate a compilation warning???
463 if not Checks_On then
468 exit when No (Checks (J));
470 if Nkind (Checks (J)) = N_Raise_Constraint_Error
471 and then Present (Condition (Checks (J)))
473 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
474 Append_To (Stmts, Checks (J));
475 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
481 Make_Raise_Constraint_Error (Internal_Static_Sloc,
482 Reason => CE_Range_Check_Failed));
485 end Append_Range_Checks;
487 ------------------------
488 -- Apply_Access_Check --
489 ------------------------
491 procedure Apply_Access_Check (N : Node_Id) is
492 P : constant Node_Id := Prefix (N);
495 -- We do not need checks if we are not generating code (i.e. the
496 -- expander is not active). This is not just an optimization, there
497 -- are cases (e.g. with pragma Debug) where generating the checks
498 -- can cause real trouble).
500 if not Expander_Active then
504 -- No check if short circuiting makes check unnecessary
506 if not Check_Needed (P, Access_Check) then
510 -- No check if accessing the Offset_To_Top component of a dispatch
511 -- table. They are safe by construction.
513 if Tagged_Type_Expansion
514 and then Present (Etype (P))
515 and then RTU_Loaded (Ada_Tags)
516 and then RTE_Available (RE_Offset_To_Top_Ptr)
517 and then Etype (P) = RTE (RE_Offset_To_Top_Ptr)
522 -- Otherwise go ahead and install the check
524 Install_Null_Excluding_Check (P);
525 end Apply_Access_Check;
527 -------------------------------
528 -- Apply_Accessibility_Check --
529 -------------------------------
531 procedure Apply_Accessibility_Check
534 Insert_Node : Node_Id)
536 Loc : constant Source_Ptr := Sloc (N);
537 Param_Ent : Entity_Id := Param_Entity (N);
538 Param_Level : Node_Id;
539 Type_Level : Node_Id;
542 if Ada_Version >= Ada_2012
543 and then not Present (Param_Ent)
544 and then Is_Entity_Name (N)
545 and then Ekind_In (Entity (N), E_Constant, E_Variable)
546 and then Present (Effective_Extra_Accessibility (Entity (N)))
548 Param_Ent := Entity (N);
549 while Present (Renamed_Object (Param_Ent)) loop
551 -- Renamed_Object must return an Entity_Name here
552 -- because of preceding "Present (E_E_A (...))" test.
554 Param_Ent := Entity (Renamed_Object (Param_Ent));
558 if Inside_A_Generic then
561 -- Only apply the run-time check if the access parameter has an
562 -- associated extra access level parameter and when the level of the
563 -- type is less deep than the level of the access parameter, and
564 -- accessibility checks are not suppressed.
566 elsif Present (Param_Ent)
567 and then Present (Extra_Accessibility (Param_Ent))
568 and then UI_Gt (Object_Access_Level (N),
569 Deepest_Type_Access_Level (Typ))
570 and then not Accessibility_Checks_Suppressed (Param_Ent)
571 and then not Accessibility_Checks_Suppressed (Typ)
574 New_Occurrence_Of (Extra_Accessibility (Param_Ent), Loc);
577 Make_Integer_Literal (Loc, Deepest_Type_Access_Level (Typ));
579 -- Raise Program_Error if the accessibility level of the access
580 -- parameter is deeper than the level of the target access type.
582 Insert_Action (Insert_Node,
583 Make_Raise_Program_Error (Loc,
586 Left_Opnd => Param_Level,
587 Right_Opnd => Type_Level),
588 Reason => PE_Accessibility_Check_Failed));
590 Analyze_And_Resolve (N);
592 end Apply_Accessibility_Check;
594 --------------------------------
595 -- Apply_Address_Clause_Check --
596 --------------------------------
598 procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id) is
599 pragma Assert (Nkind (N) = N_Freeze_Entity);
601 AC : constant Node_Id := Address_Clause (E);
602 Loc : constant Source_Ptr := Sloc (AC);
603 Typ : constant Entity_Id := Etype (E);
604 Aexp : constant Node_Id := Expression (AC);
607 -- Address expression (not necessarily the same as Aexp, for example
608 -- when Aexp is a reference to a constant, in which case Expr gets
609 -- reset to reference the value expression of the constant).
611 procedure Compile_Time_Bad_Alignment;
612 -- Post error warnings when alignment is known to be incompatible. Note
613 -- that we do not go as far as inserting a raise of Program_Error since
614 -- this is an erroneous case, and it may happen that we are lucky and an
615 -- underaligned address turns out to be OK after all.
617 --------------------------------
618 -- Compile_Time_Bad_Alignment --
619 --------------------------------
621 procedure Compile_Time_Bad_Alignment is
623 if Address_Clause_Overlay_Warnings then
625 ("?o?specified address for& may be inconsistent with alignment",
628 ("\?o?program execution may be erroneous (RM 13.3(27))",
630 Set_Address_Warning_Posted (AC);
632 end Compile_Time_Bad_Alignment;
634 -- Start of processing for Apply_Address_Clause_Check
637 -- See if alignment check needed. Note that we never need a check if the
638 -- maximum alignment is one, since the check will always succeed.
640 -- Note: we do not check for checks suppressed here, since that check
641 -- was done in Sem_Ch13 when the address clause was processed. We are
642 -- only called if checks were not suppressed. The reason for this is
643 -- that we have to delay the call to Apply_Alignment_Check till freeze
644 -- time (so that all types etc are elaborated), but we have to check
645 -- the status of check suppressing at the point of the address clause.
648 or else not Check_Address_Alignment (AC)
649 or else Maximum_Alignment = 1
654 -- Obtain expression from address clause
656 Expr := Expression (AC);
658 -- The following loop digs for the real expression to use in the check
661 -- For constant, get constant expression
663 if Is_Entity_Name (Expr)
664 and then Ekind (Entity (Expr)) = E_Constant
666 Expr := Constant_Value (Entity (Expr));
668 -- For unchecked conversion, get result to convert
670 elsif Nkind (Expr) = N_Unchecked_Type_Conversion then
671 Expr := Expression (Expr);
673 -- For (common case) of To_Address call, get argument
675 elsif Nkind (Expr) = N_Function_Call
676 and then Is_Entity_Name (Name (Expr))
677 and then Is_RTE (Entity (Name (Expr)), RE_To_Address)
679 Expr := First (Parameter_Associations (Expr));
681 if Nkind (Expr) = N_Parameter_Association then
682 Expr := Explicit_Actual_Parameter (Expr);
685 -- We finally have the real expression
692 -- See if we know that Expr has a bad alignment at compile time
694 if Compile_Time_Known_Value (Expr)
695 and then (Known_Alignment (E) or else Known_Alignment (Typ))
698 AL : Uint := Alignment (Typ);
701 -- The object alignment might be more restrictive than the
704 if Known_Alignment (E) then
708 if Expr_Value (Expr) mod AL /= 0 then
709 Compile_Time_Bad_Alignment;
715 -- If the expression has the form X'Address, then we can find out if
716 -- the object X has an alignment that is compatible with the object E.
717 -- If it hasn't or we don't know, we defer issuing the warning until
718 -- the end of the compilation to take into account back end annotations.
720 elsif Nkind (Expr) = N_Attribute_Reference
721 and then Attribute_Name (Expr) = Name_Address
722 and then Has_Compatible_Alignment (E, Prefix (Expr)) = Known_Compatible
727 -- Here we do not know if the value is acceptable. Strictly we don't
728 -- have to do anything, since if the alignment is bad, we have an
729 -- erroneous program. However we are allowed to check for erroneous
730 -- conditions and we decide to do this by default if the check is not
733 -- However, don't do the check if elaboration code is unwanted
735 if Restriction_Active (No_Elaboration_Code) then
738 -- Generate a check to raise PE if alignment may be inappropriate
741 -- If the original expression is a non-static constant, use the
742 -- name of the constant itself rather than duplicating its
743 -- defining expression, which was extracted above.
745 -- Note: Expr is empty if the address-clause is applied to in-mode
746 -- actuals (allowed by 13.1(22)).
748 if not Present (Expr)
750 (Is_Entity_Name (Expression (AC))
751 and then Ekind (Entity (Expression (AC))) = E_Constant
752 and then Nkind (Parent (Entity (Expression (AC))))
753 = N_Object_Declaration)
755 Expr := New_Copy_Tree (Expression (AC));
757 Remove_Side_Effects (Expr);
760 if No (Actions (N)) then
761 Set_Actions (N, New_List);
764 Prepend_To (Actions (N),
765 Make_Raise_Program_Error (Loc,
772 (RTE (RE_Integer_Address), Expr),
774 Make_Attribute_Reference (Loc,
775 Prefix => New_Occurrence_Of (E, Loc),
776 Attribute_Name => Name_Alignment)),
777 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
778 Reason => PE_Misaligned_Address_Value));
780 Warning_Msg := No_Error_Msg;
781 Analyze (First (Actions (N)), Suppress => All_Checks);
783 -- If the address clause generated a warning message (for example,
784 -- from Warn_On_Non_Local_Exception mode with the active restriction
785 -- No_Exception_Propagation).
787 if Warning_Msg /= No_Error_Msg then
789 -- If the expression has a known at compile time value, then
790 -- once we know the alignment of the type, we can check if the
791 -- exception will be raised or not, and if not, we don't need
792 -- the warning so we will kill the warning later on.
794 if Compile_Time_Known_Value (Expr) then
795 Alignment_Warnings.Append
796 ((E => E, A => Expr_Value (Expr), W => Warning_Msg));
799 -- Add explanation of the warning that is generated by the check
802 ("\address value may be incompatible with alignment "
803 & "of object?X?", AC);
810 -- If we have some missing run time component in configurable run time
811 -- mode then just skip the check (it is not required in any case).
813 when RE_Not_Available =>
815 end Apply_Address_Clause_Check;
817 -------------------------------------
818 -- Apply_Arithmetic_Overflow_Check --
819 -------------------------------------
821 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id) is
823 -- Use old routine in almost all cases (the only case we are treating
824 -- specially is the case of a signed integer arithmetic op with the
825 -- overflow checking mode set to MINIMIZED or ELIMINATED).
827 if Overflow_Check_Mode = Strict
828 or else not Is_Signed_Integer_Arithmetic_Op (N)
830 Apply_Arithmetic_Overflow_Strict (N);
832 -- Otherwise use the new routine for the case of a signed integer
833 -- arithmetic op, with Do_Overflow_Check set to True, and the checking
834 -- mode is MINIMIZED or ELIMINATED.
837 Apply_Arithmetic_Overflow_Minimized_Eliminated (N);
839 end Apply_Arithmetic_Overflow_Check;
841 --------------------------------------
842 -- Apply_Arithmetic_Overflow_Strict --
843 --------------------------------------
845 -- This routine is called only if the type is an integer type, and a
846 -- software arithmetic overflow check may be needed for op (add, subtract,
847 -- or multiply). This check is performed only if Software_Overflow_Checking
848 -- is enabled and Do_Overflow_Check is set. In this case we expand the
849 -- operation into a more complex sequence of tests that ensures that
850 -- overflow is properly caught.
852 -- This is used in CHECKED modes. It is identical to the code for this
853 -- cases before the big overflow earthquake, thus ensuring that in this
854 -- modes we have compatible behavior (and reliability) to what was there
855 -- before. It is also called for types other than signed integers, and if
856 -- the Do_Overflow_Check flag is off.
858 -- Note: we also call this routine if we decide in the MINIMIZED case
859 -- to give up and just generate an overflow check without any fuss.
861 procedure Apply_Arithmetic_Overflow_Strict (N : Node_Id) is
862 Loc : constant Source_Ptr := Sloc (N);
863 Typ : constant Entity_Id := Etype (N);
864 Rtyp : constant Entity_Id := Root_Type (Typ);
867 -- Nothing to do if Do_Overflow_Check not set or overflow checks
870 if not Do_Overflow_Check (N) then
874 -- An interesting special case. If the arithmetic operation appears as
875 -- the operand of a type conversion:
879 -- and all the following conditions apply:
881 -- arithmetic operation is for a signed integer type
882 -- target type type1 is a static integer subtype
883 -- range of x and y are both included in the range of type1
884 -- range of x op y is included in the range of type1
885 -- size of type1 is at least twice the result size of op
887 -- then we don't do an overflow check in any case, instead we transform
888 -- the operation so that we end up with:
890 -- type1 (type1 (x) op type1 (y))
892 -- This avoids intermediate overflow before the conversion. It is
893 -- explicitly permitted by RM 3.5.4(24):
895 -- For the execution of a predefined operation of a signed integer
896 -- type, the implementation need not raise Constraint_Error if the
897 -- result is outside the base range of the type, so long as the
898 -- correct result is produced.
900 -- It's hard to imagine that any programmer counts on the exception
901 -- being raised in this case, and in any case it's wrong coding to
902 -- have this expectation, given the RM permission. Furthermore, other
903 -- Ada compilers do allow such out of range results.
905 -- Note that we do this transformation even if overflow checking is
906 -- off, since this is precisely about giving the "right" result and
907 -- avoiding the need for an overflow check.
909 -- Note: this circuit is partially redundant with respect to the similar
910 -- processing in Exp_Ch4.Expand_N_Type_Conversion, but the latter deals
911 -- with cases that do not come through here. We still need the following
912 -- processing even with the Exp_Ch4 code in place, since we want to be
913 -- sure not to generate the arithmetic overflow check in these cases
914 -- (Exp_Ch4 would have a hard time removing them once generated).
916 if Is_Signed_Integer_Type (Typ)
917 and then Nkind (Parent (N)) = N_Type_Conversion
919 Conversion_Optimization : declare
920 Target_Type : constant Entity_Id :=
921 Base_Type (Entity (Subtype_Mark (Parent (N))));
935 if Is_Integer_Type (Target_Type)
936 and then RM_Size (Root_Type (Target_Type)) >= 2 * RM_Size (Rtyp)
938 Tlo := Expr_Value (Type_Low_Bound (Target_Type));
939 Thi := Expr_Value (Type_High_Bound (Target_Type));
942 (Left_Opnd (N), LOK, Llo, Lhi, Assume_Valid => True);
944 (Right_Opnd (N), ROK, Rlo, Rhi, Assume_Valid => True);
947 and then Tlo <= Llo and then Lhi <= Thi
948 and then Tlo <= Rlo and then Rhi <= Thi
950 Determine_Range (N, VOK, Vlo, Vhi, Assume_Valid => True);
952 if VOK and then Tlo <= Vlo and then Vhi <= Thi then
953 Rewrite (Left_Opnd (N),
954 Make_Type_Conversion (Loc,
955 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
956 Expression => Relocate_Node (Left_Opnd (N))));
958 Rewrite (Right_Opnd (N),
959 Make_Type_Conversion (Loc,
960 Subtype_Mark => New_Occurrence_Of (Target_Type, Loc),
961 Expression => Relocate_Node (Right_Opnd (N))));
963 -- Rewrite the conversion operand so that the original
964 -- node is retained, in order to avoid the warning for
965 -- redundant conversions in Resolve_Type_Conversion.
967 Rewrite (N, Relocate_Node (N));
969 Set_Etype (N, Target_Type);
971 Analyze_And_Resolve (Left_Opnd (N), Target_Type);
972 Analyze_And_Resolve (Right_Opnd (N), Target_Type);
974 -- Given that the target type is twice the size of the
975 -- source type, overflow is now impossible, so we can
976 -- safely kill the overflow check and return.
978 Set_Do_Overflow_Check (N, False);
983 end Conversion_Optimization;
986 -- Now see if an overflow check is required
989 Siz : constant Int := UI_To_Int (Esize (Rtyp));
990 Dsiz : constant Int := Siz * 2;
997 -- Skip check if back end does overflow checks, or the overflow flag
998 -- is not set anyway, or we are not doing code expansion, or the
999 -- parent node is a type conversion whose operand is an arithmetic
1000 -- operation on signed integers on which the expander can promote
1001 -- later the operands to type Integer (see Expand_N_Type_Conversion).
1003 -- Special case CLI target, where arithmetic overflow checks can be
1004 -- performed for integer and long_integer
1006 if Backend_Overflow_Checks_On_Target
1007 or else not Do_Overflow_Check (N)
1008 or else not Expander_Active
1009 or else (Present (Parent (N))
1010 and then Nkind (Parent (N)) = N_Type_Conversion
1011 and then Integer_Promotion_Possible (Parent (N)))
1013 (VM_Target = CLI_Target and then Siz >= Standard_Integer_Size)
1018 -- Otherwise, generate the full general code for front end overflow
1019 -- detection, which works by doing arithmetic in a larger type:
1025 -- Typ (Checktyp (x) op Checktyp (y));
1027 -- where Typ is the type of the original expression, and Checktyp is
1028 -- an integer type of sufficient length to hold the largest possible
1031 -- If the size of check type exceeds the size of Long_Long_Integer,
1032 -- we use a different approach, expanding to:
1034 -- typ (xxx_With_Ovflo_Check (Integer_64 (x), Integer (y)))
1036 -- where xxx is Add, Multiply or Subtract as appropriate
1038 -- Find check type if one exists
1040 if Dsiz <= Standard_Integer_Size then
1041 Ctyp := Standard_Integer;
1043 elsif Dsiz <= Standard_Long_Long_Integer_Size then
1044 Ctyp := Standard_Long_Long_Integer;
1046 -- No check type exists, use runtime call
1049 if Nkind (N) = N_Op_Add then
1050 Cent := RE_Add_With_Ovflo_Check;
1052 elsif Nkind (N) = N_Op_Multiply then
1053 Cent := RE_Multiply_With_Ovflo_Check;
1056 pragma Assert (Nkind (N) = N_Op_Subtract);
1057 Cent := RE_Subtract_With_Ovflo_Check;
1062 Make_Function_Call (Loc,
1063 Name => New_Occurrence_Of (RTE (Cent), Loc),
1064 Parameter_Associations => New_List (
1065 OK_Convert_To (RTE (RE_Integer_64), Left_Opnd (N)),
1066 OK_Convert_To (RTE (RE_Integer_64), Right_Opnd (N))))));
1068 Analyze_And_Resolve (N, Typ);
1072 -- If we fall through, we have the case where we do the arithmetic
1073 -- in the next higher type and get the check by conversion. In these
1074 -- cases Ctyp is set to the type to be used as the check type.
1076 Opnod := Relocate_Node (N);
1078 Opnd := OK_Convert_To (Ctyp, Left_Opnd (Opnod));
1081 Set_Etype (Opnd, Ctyp);
1082 Set_Analyzed (Opnd, True);
1083 Set_Left_Opnd (Opnod, Opnd);
1085 Opnd := OK_Convert_To (Ctyp, Right_Opnd (Opnod));
1088 Set_Etype (Opnd, Ctyp);
1089 Set_Analyzed (Opnd, True);
1090 Set_Right_Opnd (Opnod, Opnd);
1092 -- The type of the operation changes to the base type of the check
1093 -- type, and we reset the overflow check indication, since clearly no
1094 -- overflow is possible now that we are using a double length type.
1095 -- We also set the Analyzed flag to avoid a recursive attempt to
1098 Set_Etype (Opnod, Base_Type (Ctyp));
1099 Set_Do_Overflow_Check (Opnod, False);
1100 Set_Analyzed (Opnod, True);
1102 -- Now build the outer conversion
1104 Opnd := OK_Convert_To (Typ, Opnod);
1106 Set_Etype (Opnd, Typ);
1108 -- In the discrete type case, we directly generate the range check
1109 -- for the outer operand. This range check will implement the
1110 -- required overflow check.
1112 if Is_Discrete_Type (Typ) then
1114 Generate_Range_Check
1115 (Expression (N), Typ, CE_Overflow_Check_Failed);
1117 -- For other types, we enable overflow checking on the conversion,
1118 -- after setting the node as analyzed to prevent recursive attempts
1119 -- to expand the conversion node.
1122 Set_Analyzed (Opnd, True);
1123 Enable_Overflow_Check (Opnd);
1128 when RE_Not_Available =>
1131 end Apply_Arithmetic_Overflow_Strict;
1133 ----------------------------------------------------
1134 -- Apply_Arithmetic_Overflow_Minimized_Eliminated --
1135 ----------------------------------------------------
1137 procedure Apply_Arithmetic_Overflow_Minimized_Eliminated (Op : Node_Id) is
1138 pragma Assert (Is_Signed_Integer_Arithmetic_Op (Op));
1140 Loc : constant Source_Ptr := Sloc (Op);
1141 P : constant Node_Id := Parent (Op);
1143 LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer);
1144 -- Operands and results are of this type when we convert
1146 Result_Type : constant Entity_Id := Etype (Op);
1147 -- Original result type
1149 Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
1150 pragma Assert (Check_Mode in Minimized_Or_Eliminated);
1153 -- Ranges of values for result
1156 -- Nothing to do if our parent is one of the following:
1158 -- Another signed integer arithmetic op
1159 -- A membership operation
1160 -- A comparison operation
1162 -- In all these cases, we will process at the higher level (and then
1163 -- this node will be processed during the downwards recursion that
1164 -- is part of the processing in Minimize_Eliminate_Overflows).
1166 if Is_Signed_Integer_Arithmetic_Op (P)
1167 or else Nkind (P) in N_Membership_Test
1168 or else Nkind (P) in N_Op_Compare
1170 -- This is also true for an alternative in a case expression
1172 or else Nkind (P) = N_Case_Expression_Alternative
1174 -- This is also true for a range operand in a membership test
1176 or else (Nkind (P) = N_Range
1177 and then Nkind (Parent (P)) in N_Membership_Test)
1182 -- Otherwise, we have a top level arithmetic operation node, and this
1183 -- is where we commence the special processing for MINIMIZED/ELIMINATED
1184 -- modes. This is the case where we tell the machinery not to move into
1185 -- Bignum mode at this top level (of course the top level operation
1186 -- will still be in Bignum mode if either of its operands are of type
1189 Minimize_Eliminate_Overflows (Op, Lo, Hi, Top_Level => True);
1191 -- That call may but does not necessarily change the result type of Op.
1192 -- It is the job of this routine to undo such changes, so that at the
1193 -- top level, we have the proper type. This "undoing" is a point at
1194 -- which a final overflow check may be applied.
1196 -- If the result type was not fiddled we are all set. We go to base
1197 -- types here because things may have been rewritten to generate the
1198 -- base type of the operand types.
1200 if Base_Type (Etype (Op)) = Base_Type (Result_Type) then
1205 elsif Is_RTE (Etype (Op), RE_Bignum) then
1207 -- We need a sequence that looks like:
1209 -- Rnn : Result_Type;
1212 -- M : Mark_Id := SS_Mark;
1214 -- Rnn := Long_Long_Integer'Base (From_Bignum (Op));
1218 -- This block is inserted (using Insert_Actions), and then the node
1219 -- is replaced with a reference to Rnn.
1221 -- A special case arises if our parent is a conversion node. In this
1222 -- case no point in generating a conversion to Result_Type, we will
1223 -- let the parent handle this. Note that this special case is not
1224 -- just about optimization. Consider
1228 -- X := Long_Long_Integer'Base (A * (B ** C));
1230 -- Now the product may fit in Long_Long_Integer but not in Integer.
1231 -- In MINIMIZED/ELIMINATED mode, we don't want to introduce an
1232 -- overflow exception for this intermediate value.
1235 Blk : constant Node_Id := Make_Bignum_Block (Loc);
1236 Rnn : constant Entity_Id := Make_Temporary (Loc, 'R', Op);
1242 RHS := Convert_From_Bignum (Op);
1244 if Nkind (P) /= N_Type_Conversion then
1245 Convert_To_And_Rewrite (Result_Type, RHS);
1246 Rtype := Result_Type;
1248 -- Interesting question, do we need a check on that conversion
1249 -- operation. Answer, not if we know the result is in range.
1250 -- At the moment we are not taking advantage of this. To be
1251 -- looked at later ???
1258 (First (Statements (Handled_Statement_Sequence (Blk))),
1259 Make_Assignment_Statement (Loc,
1260 Name => New_Occurrence_Of (Rnn, Loc),
1261 Expression => RHS));
1263 Insert_Actions (Op, New_List (
1264 Make_Object_Declaration (Loc,
1265 Defining_Identifier => Rnn,
1266 Object_Definition => New_Occurrence_Of (Rtype, Loc)),
1269 Rewrite (Op, New_Occurrence_Of (Rnn, Loc));
1270 Analyze_And_Resolve (Op);
1273 -- Here we know the result is Long_Long_Integer'Base, of that it has
1274 -- been rewritten because the parent operation is a conversion. See
1275 -- Apply_Arithmetic_Overflow_Strict.Conversion_Optimization.
1279 (Etype (Op) = LLIB or else Nkind (Parent (Op)) = N_Type_Conversion);
1281 -- All we need to do here is to convert the result to the proper
1282 -- result type. As explained above for the Bignum case, we can
1283 -- omit this if our parent is a type conversion.
1285 if Nkind (P) /= N_Type_Conversion then
1286 Convert_To_And_Rewrite (Result_Type, Op);
1289 Analyze_And_Resolve (Op);
1291 end Apply_Arithmetic_Overflow_Minimized_Eliminated;
1293 ----------------------------
1294 -- Apply_Constraint_Check --
1295 ----------------------------
1297 procedure Apply_Constraint_Check
1300 No_Sliding : Boolean := False)
1302 Desig_Typ : Entity_Id;
1305 -- No checks inside a generic (check the instantiations)
1307 if Inside_A_Generic then
1311 -- Apply required constraint checks
1313 if Is_Scalar_Type (Typ) then
1314 Apply_Scalar_Range_Check (N, Typ);
1316 elsif Is_Array_Type (Typ) then
1318 -- A useful optimization: an aggregate with only an others clause
1319 -- always has the right bounds.
1321 if Nkind (N) = N_Aggregate
1322 and then No (Expressions (N))
1324 (First (Choices (First (Component_Associations (N)))))
1330 if Is_Constrained (Typ) then
1331 Apply_Length_Check (N, Typ);
1334 Apply_Range_Check (N, Typ);
1337 Apply_Range_Check (N, Typ);
1340 elsif (Is_Record_Type (Typ) or else Is_Private_Type (Typ))
1341 and then Has_Discriminants (Base_Type (Typ))
1342 and then Is_Constrained (Typ)
1344 Apply_Discriminant_Check (N, Typ);
1346 elsif Is_Access_Type (Typ) then
1348 Desig_Typ := Designated_Type (Typ);
1350 -- No checks necessary if expression statically null
1352 if Known_Null (N) then
1353 if Can_Never_Be_Null (Typ) then
1354 Install_Null_Excluding_Check (N);
1357 -- No sliding possible on access to arrays
1359 elsif Is_Array_Type (Desig_Typ) then
1360 if Is_Constrained (Desig_Typ) then
1361 Apply_Length_Check (N, Typ);
1364 Apply_Range_Check (N, Typ);
1366 elsif Has_Discriminants (Base_Type (Desig_Typ))
1367 and then Is_Constrained (Desig_Typ)
1369 Apply_Discriminant_Check (N, Typ);
1372 -- Apply the 2005 Null_Excluding check. Note that we do not apply
1373 -- this check if the constraint node is illegal, as shown by having
1374 -- an error posted. This additional guard prevents cascaded errors
1375 -- and compiler aborts on illegal programs involving Ada 2005 checks.
1377 if Can_Never_Be_Null (Typ)
1378 and then not Can_Never_Be_Null (Etype (N))
1379 and then not Error_Posted (N)
1381 Install_Null_Excluding_Check (N);
1384 end Apply_Constraint_Check;
1386 ------------------------------
1387 -- Apply_Discriminant_Check --
1388 ------------------------------
1390 procedure Apply_Discriminant_Check
1393 Lhs : Node_Id := Empty)
1395 Loc : constant Source_Ptr := Sloc (N);
1396 Do_Access : constant Boolean := Is_Access_Type (Typ);
1397 S_Typ : Entity_Id := Etype (N);
1401 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean;
1402 -- A heap object with an indefinite subtype is constrained by its
1403 -- initial value, and assigning to it requires a constraint_check.
1404 -- The target may be an explicit dereference, or a renaming of one.
1406 function Is_Aliased_Unconstrained_Component return Boolean;
1407 -- It is possible for an aliased component to have a nominal
1408 -- unconstrained subtype (through instantiation). If this is a
1409 -- discriminated component assigned in the expansion of an aggregate
1410 -- in an initialization, the check must be suppressed. This unusual
1411 -- situation requires a predicate of its own.
1413 ----------------------------------
1414 -- Denotes_Explicit_Dereference --
1415 ----------------------------------
1417 function Denotes_Explicit_Dereference (Obj : Node_Id) return Boolean is
1420 Nkind (Obj) = N_Explicit_Dereference
1422 (Is_Entity_Name (Obj)
1423 and then Present (Renamed_Object (Entity (Obj)))
1424 and then Nkind (Renamed_Object (Entity (Obj))) =
1425 N_Explicit_Dereference);
1426 end Denotes_Explicit_Dereference;
1428 ----------------------------------------
1429 -- Is_Aliased_Unconstrained_Component --
1430 ----------------------------------------
1432 function Is_Aliased_Unconstrained_Component return Boolean is
1437 if Nkind (Lhs) /= N_Selected_Component then
1440 Comp := Entity (Selector_Name (Lhs));
1441 Pref := Prefix (Lhs);
1444 if Ekind (Comp) /= E_Component
1445 or else not Is_Aliased (Comp)
1450 return not Comes_From_Source (Pref)
1451 and then In_Instance
1452 and then not Is_Constrained (Etype (Comp));
1453 end Is_Aliased_Unconstrained_Component;
1455 -- Start of processing for Apply_Discriminant_Check
1459 T_Typ := Designated_Type (Typ);
1464 -- Nothing to do if discriminant checks are suppressed or else no code
1465 -- is to be generated
1467 if not Expander_Active
1468 or else Discriminant_Checks_Suppressed (T_Typ)
1473 -- No discriminant checks necessary for an access when expression is
1474 -- statically Null. This is not only an optimization, it is fundamental
1475 -- because otherwise discriminant checks may be generated in init procs
1476 -- for types containing an access to a not-yet-frozen record, causing a
1477 -- deadly forward reference.
1479 -- Also, if the expression is of an access type whose designated type is
1480 -- incomplete, then the access value must be null and we suppress the
1483 if Known_Null (N) then
1486 elsif Is_Access_Type (S_Typ) then
1487 S_Typ := Designated_Type (S_Typ);
1489 if Ekind (S_Typ) = E_Incomplete_Type then
1494 -- If an assignment target is present, then we need to generate the
1495 -- actual subtype if the target is a parameter or aliased object with
1496 -- an unconstrained nominal subtype.
1498 -- Ada 2005 (AI-363): For Ada 2005, we limit the building of the actual
1499 -- subtype to the parameter and dereference cases, since other aliased
1500 -- objects are unconstrained (unless the nominal subtype is explicitly
1504 and then (Present (Param_Entity (Lhs))
1505 or else (Ada_Version < Ada_2005
1506 and then not Is_Constrained (T_Typ)
1507 and then Is_Aliased_View (Lhs)
1508 and then not Is_Aliased_Unconstrained_Component)
1509 or else (Ada_Version >= Ada_2005
1510 and then not Is_Constrained (T_Typ)
1511 and then Denotes_Explicit_Dereference (Lhs)
1512 and then Nkind (Original_Node (Lhs)) /=
1515 T_Typ := Get_Actual_Subtype (Lhs);
1518 -- Nothing to do if the type is unconstrained (this is the case where
1519 -- the actual subtype in the RM sense of N is unconstrained and no check
1522 if not Is_Constrained (T_Typ) then
1525 -- Ada 2005: nothing to do if the type is one for which there is a
1526 -- partial view that is constrained.
1528 elsif Ada_Version >= Ada_2005
1529 and then Object_Type_Has_Constrained_Partial_View
1530 (Typ => Base_Type (T_Typ),
1531 Scop => Current_Scope)
1536 -- Nothing to do if the type is an Unchecked_Union
1538 if Is_Unchecked_Union (Base_Type (T_Typ)) then
1542 -- Suppress checks if the subtypes are the same. The check must be
1543 -- preserved in an assignment to a formal, because the constraint is
1544 -- given by the actual.
1546 if Nkind (Original_Node (N)) /= N_Allocator
1548 or else not Is_Entity_Name (Lhs)
1549 or else No (Param_Entity (Lhs)))
1552 or else (Do_Access and then Designated_Type (Typ) = S_Typ))
1553 and then not Is_Aliased_View (Lhs)
1558 -- We can also eliminate checks on allocators with a subtype mark that
1559 -- coincides with the context type. The context type may be a subtype
1560 -- without a constraint (common case, a generic actual).
1562 elsif Nkind (Original_Node (N)) = N_Allocator
1563 and then Is_Entity_Name (Expression (Original_Node (N)))
1566 Alloc_Typ : constant Entity_Id :=
1567 Entity (Expression (Original_Node (N)));
1570 if Alloc_Typ = T_Typ
1571 or else (Nkind (Parent (T_Typ)) = N_Subtype_Declaration
1572 and then Is_Entity_Name (
1573 Subtype_Indication (Parent (T_Typ)))
1574 and then Alloc_Typ = Base_Type (T_Typ))
1582 -- See if we have a case where the types are both constrained, and all
1583 -- the constraints are constants. In this case, we can do the check
1584 -- successfully at compile time.
1586 -- We skip this check for the case where the node is rewritten as
1587 -- an allocator, because it already carries the context subtype,
1588 -- and extracting the discriminants from the aggregate is messy.
1590 if Is_Constrained (S_Typ)
1591 and then Nkind (Original_Node (N)) /= N_Allocator
1601 -- S_Typ may not have discriminants in the case where it is a
1602 -- private type completed by a default discriminated type. In that
1603 -- case, we need to get the constraints from the underlying type.
1604 -- If the underlying type is unconstrained (i.e. has no default
1605 -- discriminants) no check is needed.
1607 if Has_Discriminants (S_Typ) then
1608 Discr := First_Discriminant (S_Typ);
1609 DconS := First_Elmt (Discriminant_Constraint (S_Typ));
1612 Discr := First_Discriminant (Underlying_Type (S_Typ));
1615 (Discriminant_Constraint (Underlying_Type (S_Typ)));
1621 -- A further optimization: if T_Typ is derived from S_Typ
1622 -- without imposing a constraint, no check is needed.
1624 if Nkind (Original_Node (Parent (T_Typ))) =
1625 N_Full_Type_Declaration
1628 Type_Def : constant Node_Id :=
1629 Type_Definition (Original_Node (Parent (T_Typ)));
1631 if Nkind (Type_Def) = N_Derived_Type_Definition
1632 and then Is_Entity_Name (Subtype_Indication (Type_Def))
1633 and then Entity (Subtype_Indication (Type_Def)) = S_Typ
1641 -- Constraint may appear in full view of type
1643 if Ekind (T_Typ) = E_Private_Subtype
1644 and then Present (Full_View (T_Typ))
1647 First_Elmt (Discriminant_Constraint (Full_View (T_Typ)));
1650 First_Elmt (Discriminant_Constraint (T_Typ));
1653 while Present (Discr) loop
1654 ItemS := Node (DconS);
1655 ItemT := Node (DconT);
1657 -- For a discriminated component type constrained by the
1658 -- current instance of an enclosing type, there is no
1659 -- applicable discriminant check.
1661 if Nkind (ItemT) = N_Attribute_Reference
1662 and then Is_Access_Type (Etype (ItemT))
1663 and then Is_Entity_Name (Prefix (ItemT))
1664 and then Is_Type (Entity (Prefix (ItemT)))
1669 -- If the expressions for the discriminants are identical
1670 -- and it is side-effect free (for now just an entity),
1671 -- this may be a shared constraint, e.g. from a subtype
1672 -- without a constraint introduced as a generic actual.
1673 -- Examine other discriminants if any.
1676 and then Is_Entity_Name (ItemS)
1680 elsif not Is_OK_Static_Expression (ItemS)
1681 or else not Is_OK_Static_Expression (ItemT)
1685 elsif Expr_Value (ItemS) /= Expr_Value (ItemT) then
1686 if Do_Access then -- needs run-time check.
1689 Apply_Compile_Time_Constraint_Error
1690 (N, "incorrect value for discriminant&??",
1691 CE_Discriminant_Check_Failed, Ent => Discr);
1698 Next_Discriminant (Discr);
1707 -- Here we need a discriminant check. First build the expression
1708 -- for the comparisons of the discriminants:
1710 -- (n.disc1 /= typ.disc1) or else
1711 -- (n.disc2 /= typ.disc2) or else
1713 -- (n.discn /= typ.discn)
1715 Cond := Build_Discriminant_Checks (N, T_Typ);
1717 -- If Lhs is set and is a parameter, then the condition is guarded by:
1718 -- lhs'constrained and then (condition built above)
1720 if Present (Param_Entity (Lhs)) then
1724 Make_Attribute_Reference (Loc,
1725 Prefix => New_Occurrence_Of (Param_Entity (Lhs), Loc),
1726 Attribute_Name => Name_Constrained),
1727 Right_Opnd => Cond);
1731 Cond := Guard_Access (Cond, Loc, N);
1735 Make_Raise_Constraint_Error (Loc,
1737 Reason => CE_Discriminant_Check_Failed));
1738 end Apply_Discriminant_Check;
1740 -------------------------
1741 -- Apply_Divide_Checks --
1742 -------------------------
1744 procedure Apply_Divide_Checks (N : Node_Id) is
1745 Loc : constant Source_Ptr := Sloc (N);
1746 Typ : constant Entity_Id := Etype (N);
1747 Left : constant Node_Id := Left_Opnd (N);
1748 Right : constant Node_Id := Right_Opnd (N);
1750 Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
1751 -- Current overflow checking mode
1761 pragma Warnings (Off, Lhi);
1762 -- Don't actually use this value
1765 -- If we are operating in MINIMIZED or ELIMINATED mode, and we are
1766 -- operating on signed integer types, then the only thing this routine
1767 -- does is to call Apply_Arithmetic_Overflow_Minimized_Eliminated. That
1768 -- procedure will (possibly later on during recursive downward calls),
1769 -- ensure that any needed overflow/division checks are properly applied.
1771 if Mode in Minimized_Or_Eliminated
1772 and then Is_Signed_Integer_Type (Typ)
1774 Apply_Arithmetic_Overflow_Minimized_Eliminated (N);
1778 -- Proceed here in SUPPRESSED or CHECKED modes
1781 and then not Backend_Divide_Checks_On_Target
1782 and then Check_Needed (Right, Division_Check)
1784 Determine_Range (Right, ROK, Rlo, Rhi, Assume_Valid => True);
1786 -- Deal with division check
1788 if Do_Division_Check (N)
1789 and then not Division_Checks_Suppressed (Typ)
1791 Apply_Division_Check (N, Rlo, Rhi, ROK);
1794 -- Deal with overflow check
1796 if Do_Overflow_Check (N)
1797 and then not Overflow_Checks_Suppressed (Etype (N))
1799 -- Test for extremely annoying case of xxx'First divided by -1
1800 -- for division of signed integer types (only overflow case).
1802 if Nkind (N) = N_Op_Divide
1803 and then Is_Signed_Integer_Type (Typ)
1805 Determine_Range (Left, LOK, Llo, Lhi, Assume_Valid => True);
1806 LLB := Expr_Value (Type_Low_Bound (Base_Type (Typ)));
1808 if ((not ROK) or else (Rlo <= (-1) and then (-1) <= Rhi))
1810 ((not LOK) or else (Llo = LLB))
1813 Make_Raise_Constraint_Error (Loc,
1819 Duplicate_Subexpr_Move_Checks (Left),
1820 Right_Opnd => Make_Integer_Literal (Loc, LLB)),
1824 Left_Opnd => Duplicate_Subexpr (Right),
1825 Right_Opnd => Make_Integer_Literal (Loc, -1))),
1827 Reason => CE_Overflow_Check_Failed));
1832 end Apply_Divide_Checks;
1834 --------------------------
1835 -- Apply_Division_Check --
1836 --------------------------
1838 procedure Apply_Division_Check
1844 pragma Assert (Do_Division_Check (N));
1846 Loc : constant Source_Ptr := Sloc (N);
1847 Right : constant Node_Id := Right_Opnd (N);
1851 and then not Backend_Divide_Checks_On_Target
1852 and then Check_Needed (Right, Division_Check)
1854 -- See if division by zero possible, and if so generate test. This
1855 -- part of the test is not controlled by the -gnato switch, since
1856 -- it is a Division_Check and not an Overflow_Check.
1858 if Do_Division_Check (N) then
1859 if (not ROK) or else (Rlo <= 0 and then 0 <= Rhi) then
1861 Make_Raise_Constraint_Error (Loc,
1864 Left_Opnd => Duplicate_Subexpr_Move_Checks (Right),
1865 Right_Opnd => Make_Integer_Literal (Loc, 0)),
1866 Reason => CE_Divide_By_Zero));
1870 end Apply_Division_Check;
1872 ----------------------------------
1873 -- Apply_Float_Conversion_Check --
1874 ----------------------------------
1876 -- Let F and I be the source and target types of the conversion. The RM
1877 -- specifies that a floating-point value X is rounded to the nearest
1878 -- integer, with halfway cases being rounded away from zero. The rounded
1879 -- value of X is checked against I'Range.
1881 -- The catch in the above paragraph is that there is no good way to know
1882 -- whether the round-to-integer operation resulted in overflow. A remedy is
1883 -- to perform a range check in the floating-point domain instead, however:
1885 -- (1) The bounds may not be known at compile time
1886 -- (2) The check must take into account rounding or truncation.
1887 -- (3) The range of type I may not be exactly representable in F.
1888 -- (4) For the rounding case, The end-points I'First - 0.5 and
1889 -- I'Last + 0.5 may or may not be in range, depending on the
1890 -- sign of I'First and I'Last.
1891 -- (5) X may be a NaN, which will fail any comparison
1893 -- The following steps correctly convert X with rounding:
1895 -- (1) If either I'First or I'Last is not known at compile time, use
1896 -- I'Base instead of I in the next three steps and perform a
1897 -- regular range check against I'Range after conversion.
1898 -- (2) If I'First - 0.5 is representable in F then let Lo be that
1899 -- value and define Lo_OK as (I'First > 0). Otherwise, let Lo be
1900 -- F'Machine (I'First) and let Lo_OK be (Lo >= I'First).
1901 -- In other words, take one of the closest floating-point numbers
1902 -- (which is an integer value) to I'First, and see if it is in
1904 -- (3) If I'Last + 0.5 is representable in F then let Hi be that value
1905 -- and define Hi_OK as (I'Last < 0). Otherwise, let Hi be
1906 -- F'Machine (I'Last) and let Hi_OK be (Hi <= I'Last).
1907 -- (4) Raise CE when (Lo_OK and X < Lo) or (not Lo_OK and X <= Lo)
1908 -- or (Hi_OK and X > Hi) or (not Hi_OK and X >= Hi)
1910 -- For the truncating case, replace steps (2) and (3) as follows:
1911 -- (2) If I'First > 0, then let Lo be F'Pred (I'First) and let Lo_OK
1912 -- be False. Otherwise, let Lo be F'Succ (I'First - 1) and let
1914 -- (3) If I'Last < 0, then let Hi be F'Succ (I'Last) and let Hi_OK
1915 -- be False. Otherwise let Hi be F'Pred (I'Last + 1) and let
1918 procedure Apply_Float_Conversion_Check
1920 Target_Typ : Entity_Id)
1922 LB : constant Node_Id := Type_Low_Bound (Target_Typ);
1923 HB : constant Node_Id := Type_High_Bound (Target_Typ);
1924 Loc : constant Source_Ptr := Sloc (Ck_Node);
1925 Expr_Type : constant Entity_Id := Base_Type (Etype (Ck_Node));
1926 Target_Base : constant Entity_Id :=
1927 Implementation_Base_Type (Target_Typ);
1929 Par : constant Node_Id := Parent (Ck_Node);
1930 pragma Assert (Nkind (Par) = N_Type_Conversion);
1931 -- Parent of check node, must be a type conversion
1933 Truncate : constant Boolean := Float_Truncate (Par);
1934 Max_Bound : constant Uint :=
1936 (Machine_Radix_Value (Expr_Type),
1937 Machine_Mantissa_Value (Expr_Type) - 1) - 1;
1939 -- Largest bound, so bound plus or minus half is a machine number of F
1941 Ifirst, Ilast : Uint;
1942 -- Bounds of integer type
1945 -- Bounds to check in floating-point domain
1947 Lo_OK, Hi_OK : Boolean;
1948 -- True iff Lo resp. Hi belongs to I'Range
1950 Lo_Chk, Hi_Chk : Node_Id;
1951 -- Expressions that are False iff check fails
1953 Reason : RT_Exception_Code;
1956 -- We do not need checks if we are not generating code (i.e. the full
1957 -- expander is not active). In SPARK mode, we specifically don't want
1958 -- the frontend to expand these checks, which are dealt with directly
1959 -- in the formal verification backend.
1961 if not Expander_Active then
1965 if not Compile_Time_Known_Value (LB)
1966 or not Compile_Time_Known_Value (HB)
1969 -- First check that the value falls in the range of the base type,
1970 -- to prevent overflow during conversion and then perform a
1971 -- regular range check against the (dynamic) bounds.
1973 pragma Assert (Target_Base /= Target_Typ);
1975 Temp : constant Entity_Id := Make_Temporary (Loc, 'T', Par);
1978 Apply_Float_Conversion_Check (Ck_Node, Target_Base);
1979 Set_Etype (Temp, Target_Base);
1981 Insert_Action (Parent (Par),
1982 Make_Object_Declaration (Loc,
1983 Defining_Identifier => Temp,
1984 Object_Definition => New_Occurrence_Of (Target_Typ, Loc),
1985 Expression => New_Copy_Tree (Par)),
1986 Suppress => All_Checks);
1989 Make_Raise_Constraint_Error (Loc,
1992 Left_Opnd => New_Occurrence_Of (Temp, Loc),
1993 Right_Opnd => New_Occurrence_Of (Target_Typ, Loc)),
1994 Reason => CE_Range_Check_Failed));
1995 Rewrite (Par, New_Occurrence_Of (Temp, Loc));
2001 -- Get the (static) bounds of the target type
2003 Ifirst := Expr_Value (LB);
2004 Ilast := Expr_Value (HB);
2006 -- A simple optimization: if the expression is a universal literal,
2007 -- we can do the comparison with the bounds and the conversion to
2008 -- an integer type statically. The range checks are unchanged.
2010 if Nkind (Ck_Node) = N_Real_Literal
2011 and then Etype (Ck_Node) = Universal_Real
2012 and then Is_Integer_Type (Target_Typ)
2013 and then Nkind (Parent (Ck_Node)) = N_Type_Conversion
2016 Int_Val : constant Uint := UR_To_Uint (Realval (Ck_Node));
2019 if Int_Val <= Ilast and then Int_Val >= Ifirst then
2021 -- Conversion is safe
2023 Rewrite (Parent (Ck_Node),
2024 Make_Integer_Literal (Loc, UI_To_Int (Int_Val)));
2025 Analyze_And_Resolve (Parent (Ck_Node), Target_Typ);
2031 -- Check against lower bound
2033 if Truncate and then Ifirst > 0 then
2034 Lo := Pred (Expr_Type, UR_From_Uint (Ifirst));
2038 Lo := Succ (Expr_Type, UR_From_Uint (Ifirst - 1));
2041 elsif abs (Ifirst) < Max_Bound then
2042 Lo := UR_From_Uint (Ifirst) - Ureal_Half;
2043 Lo_OK := (Ifirst > 0);
2046 Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Ck_Node);
2047 Lo_OK := (Lo >= UR_From_Uint (Ifirst));
2052 -- Lo_Chk := (X >= Lo)
2054 Lo_Chk := Make_Op_Ge (Loc,
2055 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2056 Right_Opnd => Make_Real_Literal (Loc, Lo));
2059 -- Lo_Chk := (X > Lo)
2061 Lo_Chk := Make_Op_Gt (Loc,
2062 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2063 Right_Opnd => Make_Real_Literal (Loc, Lo));
2066 -- Check against higher bound
2068 if Truncate and then Ilast < 0 then
2069 Hi := Succ (Expr_Type, UR_From_Uint (Ilast));
2073 Hi := Pred (Expr_Type, UR_From_Uint (Ilast + 1));
2076 elsif abs (Ilast) < Max_Bound then
2077 Hi := UR_From_Uint (Ilast) + Ureal_Half;
2078 Hi_OK := (Ilast < 0);
2080 Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Ck_Node);
2081 Hi_OK := (Hi <= UR_From_Uint (Ilast));
2086 -- Hi_Chk := (X <= Hi)
2088 Hi_Chk := Make_Op_Le (Loc,
2089 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2090 Right_Opnd => Make_Real_Literal (Loc, Hi));
2093 -- Hi_Chk := (X < Hi)
2095 Hi_Chk := Make_Op_Lt (Loc,
2096 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
2097 Right_Opnd => Make_Real_Literal (Loc, Hi));
2100 -- If the bounds of the target type are the same as those of the base
2101 -- type, the check is an overflow check as a range check is not
2102 -- performed in these cases.
2104 if Expr_Value (Type_Low_Bound (Target_Base)) = Ifirst
2105 and then Expr_Value (Type_High_Bound (Target_Base)) = Ilast
2107 Reason := CE_Overflow_Check_Failed;
2109 Reason := CE_Range_Check_Failed;
2112 -- Raise CE if either conditions does not hold
2114 Insert_Action (Ck_Node,
2115 Make_Raise_Constraint_Error (Loc,
2116 Condition => Make_Op_Not (Loc, Make_And_Then (Loc, Lo_Chk, Hi_Chk)),
2118 end Apply_Float_Conversion_Check;
2120 ------------------------
2121 -- Apply_Length_Check --
2122 ------------------------
2124 procedure Apply_Length_Check
2126 Target_Typ : Entity_Id;
2127 Source_Typ : Entity_Id := Empty)
2130 Apply_Selected_Length_Checks
2131 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
2132 end Apply_Length_Check;
2134 -------------------------------------
2135 -- Apply_Parameter_Aliasing_Checks --
2136 -------------------------------------
2138 procedure Apply_Parameter_Aliasing_Checks
2142 Loc : constant Source_Ptr := Sloc (Call);
2144 function May_Cause_Aliasing
2145 (Formal_1 : Entity_Id;
2146 Formal_2 : Entity_Id) return Boolean;
2147 -- Determine whether two formal parameters can alias each other
2148 -- depending on their modes.
2150 function Original_Actual (N : Node_Id) return Node_Id;
2151 -- The expander may replace an actual with a temporary for the sake of
2152 -- side effect removal. The temporary may hide a potential aliasing as
2153 -- it does not share the address of the actual. This routine attempts
2154 -- to retrieve the original actual.
2156 procedure Overlap_Check
2157 (Actual_1 : Node_Id;
2159 Formal_1 : Entity_Id;
2160 Formal_2 : Entity_Id;
2161 Check : in out Node_Id);
2162 -- Create a check to determine whether Actual_1 overlaps with Actual_2.
2163 -- If detailed exception messages are enabled, the check is augmented to
2164 -- provide information about the names of the corresponding formals. See
2165 -- the body for details. Actual_1 and Actual_2 denote the two actuals to
2166 -- be tested. Formal_1 and Formal_2 denote the corresponding formals.
2167 -- Check contains all and-ed simple tests generated so far or remains
2168 -- unchanged in the case of detailed exception messaged.
2170 ------------------------
2171 -- May_Cause_Aliasing --
2172 ------------------------
2174 function May_Cause_Aliasing
2175 (Formal_1 : Entity_Id;
2176 Formal_2 : Entity_Id) return Boolean
2179 -- The following combination cannot lead to aliasing
2181 -- Formal 1 Formal 2
2184 if Ekind (Formal_1) = E_In_Parameter
2186 Ekind (Formal_2) = E_In_Parameter
2190 -- The following combinations may lead to aliasing
2192 -- Formal 1 Formal 2
2202 end May_Cause_Aliasing;
2204 ---------------------
2205 -- Original_Actual --
2206 ---------------------
2208 function Original_Actual (N : Node_Id) return Node_Id is
2210 if Nkind (N) = N_Type_Conversion then
2211 return Expression (N);
2213 -- The expander created a temporary to capture the result of a type
2214 -- conversion where the expression is the real actual.
2216 elsif Nkind (N) = N_Identifier
2217 and then Present (Original_Node (N))
2218 and then Nkind (Original_Node (N)) = N_Type_Conversion
2220 return Expression (Original_Node (N));
2224 end Original_Actual;
2230 procedure Overlap_Check
2231 (Actual_1 : Node_Id;
2233 Formal_1 : Entity_Id;
2234 Formal_2 : Entity_Id;
2235 Check : in out Node_Id)
2238 ID_Casing : constant Casing_Type :=
2239 Identifier_Casing (Source_Index (Current_Sem_Unit));
2243 -- Actual_1'Overlaps_Storage (Actual_2)
2246 Make_Attribute_Reference (Loc,
2247 Prefix => New_Copy_Tree (Original_Actual (Actual_1)),
2248 Attribute_Name => Name_Overlaps_Storage,
2250 New_List (New_Copy_Tree (Original_Actual (Actual_2))));
2252 -- Generate the following check when detailed exception messages are
2255 -- if Actual_1'Overlaps_Storage (Actual_2) then
2256 -- raise Program_Error with <detailed message>;
2259 if Exception_Extra_Info then
2262 -- Do not generate location information for internal calls
2264 if Comes_From_Source (Call) then
2265 Store_String_Chars (Build_Location_String (Loc));
2266 Store_String_Char (' ');
2269 Store_String_Chars ("aliased parameters, actuals for """);
2271 Get_Name_String (Chars (Formal_1));
2272 Set_Casing (ID_Casing);
2273 Store_String_Chars (Name_Buffer (1 .. Name_Len));
2275 Store_String_Chars (""" and """);
2277 Get_Name_String (Chars (Formal_2));
2278 Set_Casing (ID_Casing);
2279 Store_String_Chars (Name_Buffer (1 .. Name_Len));
2281 Store_String_Chars (""" overlap");
2283 Insert_Action (Call,
2284 Make_If_Statement (Loc,
2286 Then_Statements => New_List (
2287 Make_Raise_Statement (Loc,
2289 New_Occurrence_Of (Standard_Program_Error, Loc),
2290 Expression => Make_String_Literal (Loc, End_String)))));
2292 -- Create a sequence of overlapping checks by and-ing them all
2302 Right_Opnd => Cond);
2312 Formal_1 : Entity_Id;
2313 Formal_2 : Entity_Id;
2315 -- Start of processing for Apply_Parameter_Aliasing_Checks
2320 Actual_1 := First_Actual (Call);
2321 Formal_1 := First_Formal (Subp);
2322 while Present (Actual_1) and then Present (Formal_1) loop
2324 -- Ensure that the actual is an object that is not passed by value.
2325 -- Elementary types are always passed by value, therefore actuals of
2326 -- such types cannot lead to aliasing.
2328 if Is_Object_Reference (Original_Actual (Actual_1))
2329 and then not Is_Elementary_Type (Etype (Original_Actual (Actual_1)))
2331 Actual_2 := Next_Actual (Actual_1);
2332 Formal_2 := Next_Formal (Formal_1);
2333 while Present (Actual_2) and then Present (Formal_2) loop
2335 -- The other actual we are testing against must also denote
2336 -- a non pass-by-value object. Generate the check only when
2337 -- the mode of the two formals may lead to aliasing.
2339 if Is_Object_Reference (Original_Actual (Actual_2))
2341 Is_Elementary_Type (Etype (Original_Actual (Actual_2)))
2342 and then May_Cause_Aliasing (Formal_1, Formal_2)
2345 (Actual_1 => Actual_1,
2346 Actual_2 => Actual_2,
2347 Formal_1 => Formal_1,
2348 Formal_2 => Formal_2,
2352 Next_Actual (Actual_2);
2353 Next_Formal (Formal_2);
2357 Next_Actual (Actual_1);
2358 Next_Formal (Formal_1);
2361 -- Place a simple check right before the call
2363 if Present (Check) and then not Exception_Extra_Info then
2364 Insert_Action (Call,
2365 Make_Raise_Program_Error (Loc,
2367 Reason => PE_Aliased_Parameters));
2369 end Apply_Parameter_Aliasing_Checks;
2371 -------------------------------------
2372 -- Apply_Parameter_Validity_Checks --
2373 -------------------------------------
2375 procedure Apply_Parameter_Validity_Checks (Subp : Entity_Id) is
2376 Subp_Decl : Node_Id;
2378 procedure Add_Validity_Check
2379 (Context : Entity_Id;
2381 For_Result : Boolean := False);
2382 -- Add a single 'Valid[_Scalar] check which verifies the initialization
2383 -- of Context. PPC_Nam denotes the pre or post condition pragma name.
2384 -- Set flag For_Result when to verify the result of a function.
2386 procedure Build_PPC_Pragma (PPC_Nam : Name_Id; Check : Node_Id);
2387 -- Create a pre or post condition pragma with name PPC_Nam which
2388 -- tests expression Check.
2390 ------------------------
2391 -- Add_Validity_Check --
2392 ------------------------
2394 procedure Add_Validity_Check
2395 (Context : Entity_Id;
2397 For_Result : Boolean := False)
2399 Loc : constant Source_Ptr := Sloc (Subp);
2400 Typ : constant Entity_Id := Etype (Context);
2405 -- Pick the proper version of 'Valid depending on the type of the
2406 -- context. If the context is not eligible for such a check, return.
2408 if Is_Scalar_Type (Typ) then
2410 elsif not No_Scalar_Parts (Typ) then
2411 Nam := Name_Valid_Scalars;
2416 -- Step 1: Create the expression to verify the validity of the
2419 Check := New_Occurrence_Of (Context, Loc);
2421 -- When processing a function result, use 'Result. Generate
2426 Make_Attribute_Reference (Loc,
2428 Attribute_Name => Name_Result);
2432 -- Context['Result]'Valid[_Scalars]
2435 Make_Attribute_Reference (Loc,
2437 Attribute_Name => Nam);
2439 -- Step 2: Create a pre or post condition pragma
2441 Build_PPC_Pragma (PPC_Nam, Check);
2442 end Add_Validity_Check;
2444 ----------------------
2445 -- Build_PPC_Pragma --
2446 ----------------------
2448 procedure Build_PPC_Pragma (PPC_Nam : Name_Id; Check : Node_Id) is
2449 Loc : constant Source_Ptr := Sloc (Subp);
2456 Pragma_Identifier => Make_Identifier (Loc, PPC_Nam),
2457 Pragma_Argument_Associations => New_List (
2458 Make_Pragma_Argument_Association (Loc,
2459 Chars => Name_Check,
2460 Expression => Check)));
2462 -- Add a message unless exception messages are suppressed
2464 if not Exception_Locations_Suppressed then
2465 Append_To (Pragma_Argument_Associations (Prag),
2466 Make_Pragma_Argument_Association (Loc,
2467 Chars => Name_Message,
2469 Make_String_Literal (Loc,
2470 Strval => "failed " & Get_Name_String (PPC_Nam) &
2471 " from " & Build_Location_String (Loc))));
2474 -- Insert the pragma in the tree
2476 if Nkind (Parent (Subp_Decl)) = N_Compilation_Unit then
2477 Add_Global_Declaration (Prag);
2480 -- PPC pragmas associated with subprogram bodies must be inserted in
2481 -- the declarative part of the body.
2483 elsif Nkind (Subp_Decl) = N_Subprogram_Body then
2484 Decls := Declarations (Subp_Decl);
2488 Set_Declarations (Subp_Decl, Decls);
2491 Prepend_To (Decls, Prag);
2493 -- Ensure the proper visibility of the subprogram body and its
2500 -- For subprogram declarations insert the PPC pragma right after the
2501 -- declarative node.
2504 Insert_After_And_Analyze (Subp_Decl, Prag);
2506 end Build_PPC_Pragma;
2511 Subp_Spec : Node_Id;
2513 -- Start of processing for Apply_Parameter_Validity_Checks
2516 -- Extract the subprogram specification and declaration nodes
2518 Subp_Spec := Parent (Subp);
2520 if Nkind (Subp_Spec) = N_Defining_Program_Unit_Name then
2521 Subp_Spec := Parent (Subp_Spec);
2524 Subp_Decl := Parent (Subp_Spec);
2526 if not Comes_From_Source (Subp)
2528 -- Do not process formal subprograms because the corresponding actual
2529 -- will receive the proper checks when the instance is analyzed.
2531 or else Is_Formal_Subprogram (Subp)
2533 -- Do not process imported subprograms since pre and post conditions
2534 -- are never verified on routines coming from a different language.
2536 or else Is_Imported (Subp)
2537 or else Is_Intrinsic_Subprogram (Subp)
2539 -- The PPC pragmas generated by this routine do not correspond to
2540 -- source aspects, therefore they cannot be applied to abstract
2543 or else Nkind (Subp_Decl) = N_Abstract_Subprogram_Declaration
2545 -- Do not consider subprogram renaminds because the renamed entity
2546 -- already has the proper PPC pragmas.
2548 or else Nkind (Subp_Decl) = N_Subprogram_Renaming_Declaration
2550 -- Do not process null procedures because there is no benefit of
2551 -- adding the checks to a no action routine.
2553 or else (Nkind (Subp_Spec) = N_Procedure_Specification
2554 and then Null_Present (Subp_Spec))
2559 -- Inspect all the formals applying aliasing and scalar initialization
2560 -- checks where applicable.
2562 Formal := First_Formal (Subp);
2563 while Present (Formal) loop
2565 -- Generate the following scalar initialization checks for each
2566 -- formal parameter:
2568 -- mode IN - Pre => Formal'Valid[_Scalars]
2569 -- mode IN OUT - Pre, Post => Formal'Valid[_Scalars]
2570 -- mode OUT - Post => Formal'Valid[_Scalars]
2572 if Check_Validity_Of_Parameters then
2573 if Ekind_In (Formal, E_In_Parameter, E_In_Out_Parameter) then
2574 Add_Validity_Check (Formal, Name_Precondition, False);
2577 if Ekind_In (Formal, E_In_Out_Parameter, E_Out_Parameter) then
2578 Add_Validity_Check (Formal, Name_Postcondition, False);
2582 Next_Formal (Formal);
2585 -- Generate following scalar initialization check for function result:
2587 -- Post => Subp'Result'Valid[_Scalars]
2589 if Check_Validity_Of_Parameters and then Ekind (Subp) = E_Function then
2590 Add_Validity_Check (Subp, Name_Postcondition, True);
2592 end Apply_Parameter_Validity_Checks;
2594 ---------------------------
2595 -- Apply_Predicate_Check --
2596 ---------------------------
2598 procedure Apply_Predicate_Check (N : Node_Id; Typ : Entity_Id) is
2602 if Present (Predicate_Function (Typ)) then
2605 while Present (S) and then not Is_Subprogram (S) loop
2609 -- A predicate check does not apply within internally generated
2610 -- subprograms, such as TSS functions.
2612 if Within_Internal_Subprogram then
2615 -- If the check appears within the predicate function itself, it
2616 -- means that the user specified a check whose formal is the
2617 -- predicated subtype itself, rather than some covering type. This
2618 -- is likely to be a common error, and thus deserves a warning.
2620 elsif Present (S) and then S = Predicate_Function (Typ) then
2622 ("predicate check includes a function call that "
2623 & "requires a predicate check??", Parent (N));
2625 ("\this will result in infinite recursion??", Parent (N));
2627 Make_Raise_Storage_Error (Sloc (N),
2628 Reason => SE_Infinite_Recursion));
2630 -- Here for normal case of predicate active
2633 -- If the type has a static predicate and the expression is known
2634 -- at compile time, see if the expression satisfies the predicate.
2636 Check_Expression_Against_Static_Predicate (N, Typ);
2639 Make_Predicate_Check (Typ, Duplicate_Subexpr (N)));
2642 end Apply_Predicate_Check;
2644 -----------------------
2645 -- Apply_Range_Check --
2646 -----------------------
2648 procedure Apply_Range_Check
2650 Target_Typ : Entity_Id;
2651 Source_Typ : Entity_Id := Empty)
2654 Apply_Selected_Range_Checks
2655 (Ck_Node, Target_Typ, Source_Typ, Do_Static => False);
2656 end Apply_Range_Check;
2658 ------------------------------
2659 -- Apply_Scalar_Range_Check --
2660 ------------------------------
2662 -- Note that Apply_Scalar_Range_Check never turns the Do_Range_Check flag
2663 -- off if it is already set on.
2665 procedure Apply_Scalar_Range_Check
2667 Target_Typ : Entity_Id;
2668 Source_Typ : Entity_Id := Empty;
2669 Fixed_Int : Boolean := False)
2671 Parnt : constant Node_Id := Parent (Expr);
2673 Arr : Node_Id := Empty; -- initialize to prevent warning
2674 Arr_Typ : Entity_Id := Empty; -- initialize to prevent warning
2677 Is_Subscr_Ref : Boolean;
2678 -- Set true if Expr is a subscript
2680 Is_Unconstrained_Subscr_Ref : Boolean;
2681 -- Set true if Expr is a subscript of an unconstrained array. In this
2682 -- case we do not attempt to do an analysis of the value against the
2683 -- range of the subscript, since we don't know the actual subtype.
2686 -- Set to True if Expr should be regarded as a real value even though
2687 -- the type of Expr might be discrete.
2689 procedure Bad_Value;
2690 -- Procedure called if value is determined to be out of range
2696 procedure Bad_Value is
2698 Apply_Compile_Time_Constraint_Error
2699 (Expr, "value not in range of}??", CE_Range_Check_Failed,
2704 -- Start of processing for Apply_Scalar_Range_Check
2707 -- Return if check obviously not needed
2710 -- Not needed inside generic
2714 -- Not needed if previous error
2716 or else Target_Typ = Any_Type
2717 or else Nkind (Expr) = N_Error
2719 -- Not needed for non-scalar type
2721 or else not Is_Scalar_Type (Target_Typ)
2723 -- Not needed if we know node raises CE already
2725 or else Raises_Constraint_Error (Expr)
2730 -- Now, see if checks are suppressed
2733 Is_List_Member (Expr) and then Nkind (Parnt) = N_Indexed_Component;
2735 if Is_Subscr_Ref then
2736 Arr := Prefix (Parnt);
2737 Arr_Typ := Get_Actual_Subtype_If_Available (Arr);
2739 if Is_Access_Type (Arr_Typ) then
2740 Arr_Typ := Designated_Type (Arr_Typ);
2744 if not Do_Range_Check (Expr) then
2746 -- Subscript reference. Check for Index_Checks suppressed
2748 if Is_Subscr_Ref then
2750 -- Check array type and its base type
2752 if Index_Checks_Suppressed (Arr_Typ)
2753 or else Index_Checks_Suppressed (Base_Type (Arr_Typ))
2757 -- Check array itself if it is an entity name
2759 elsif Is_Entity_Name (Arr)
2760 and then Index_Checks_Suppressed (Entity (Arr))
2764 -- Check expression itself if it is an entity name
2766 elsif Is_Entity_Name (Expr)
2767 and then Index_Checks_Suppressed (Entity (Expr))
2772 -- All other cases, check for Range_Checks suppressed
2775 -- Check target type and its base type
2777 if Range_Checks_Suppressed (Target_Typ)
2778 or else Range_Checks_Suppressed (Base_Type (Target_Typ))
2782 -- Check expression itself if it is an entity name
2784 elsif Is_Entity_Name (Expr)
2785 and then Range_Checks_Suppressed (Entity (Expr))
2789 -- If Expr is part of an assignment statement, then check left
2790 -- side of assignment if it is an entity name.
2792 elsif Nkind (Parnt) = N_Assignment_Statement
2793 and then Is_Entity_Name (Name (Parnt))
2794 and then Range_Checks_Suppressed (Entity (Name (Parnt)))
2801 -- Do not set range checks if they are killed
2803 if Nkind (Expr) = N_Unchecked_Type_Conversion
2804 and then Kill_Range_Check (Expr)
2809 -- Do not set range checks for any values from System.Scalar_Values
2810 -- since the whole idea of such values is to avoid checking them.
2812 if Is_Entity_Name (Expr)
2813 and then Is_RTU (Scope (Entity (Expr)), System_Scalar_Values)
2818 -- Now see if we need a check
2820 if No (Source_Typ) then
2821 S_Typ := Etype (Expr);
2823 S_Typ := Source_Typ;
2826 if not Is_Scalar_Type (S_Typ) or else S_Typ = Any_Type then
2830 Is_Unconstrained_Subscr_Ref :=
2831 Is_Subscr_Ref and then not Is_Constrained (Arr_Typ);
2833 -- Special checks for floating-point type
2835 if Is_Floating_Point_Type (S_Typ) then
2837 -- Always do a range check if the source type includes infinities and
2838 -- the target type does not include infinities. We do not do this if
2839 -- range checks are killed.
2841 if Has_Infinities (S_Typ)
2842 and then not Has_Infinities (Target_Typ)
2844 Enable_Range_Check (Expr);
2846 -- Always do a range check for operators if option set
2848 elsif Check_Float_Overflow and then Nkind (Expr) in N_Op then
2849 Enable_Range_Check (Expr);
2853 -- Return if we know expression is definitely in the range of the target
2854 -- type as determined by Determine_Range. Right now we only do this for
2855 -- discrete types, and not fixed-point or floating-point types.
2857 -- The additional less-precise tests below catch these cases
2859 -- Note: skip this if we are given a source_typ, since the point of
2860 -- supplying a Source_Typ is to stop us looking at the expression.
2861 -- We could sharpen this test to be out parameters only ???
2863 if Is_Discrete_Type (Target_Typ)
2864 and then Is_Discrete_Type (Etype (Expr))
2865 and then not Is_Unconstrained_Subscr_Ref
2866 and then No (Source_Typ)
2869 Tlo : constant Node_Id := Type_Low_Bound (Target_Typ);
2870 Thi : constant Node_Id := Type_High_Bound (Target_Typ);
2875 if Compile_Time_Known_Value (Tlo)
2876 and then Compile_Time_Known_Value (Thi)
2879 Lov : constant Uint := Expr_Value (Tlo);
2880 Hiv : constant Uint := Expr_Value (Thi);
2883 -- If range is null, we for sure have a constraint error
2884 -- (we don't even need to look at the value involved,
2885 -- since all possible values will raise CE).
2892 -- Otherwise determine range of value
2894 Determine_Range (Expr, OK, Lo, Hi, Assume_Valid => True);
2898 -- If definitely in range, all OK
2900 if Lo >= Lov and then Hi <= Hiv then
2903 -- If definitely not in range, warn
2905 elsif Lov > Hi or else Hiv < Lo then
2909 -- Otherwise we don't know
2921 Is_Floating_Point_Type (S_Typ)
2922 or else (Is_Fixed_Point_Type (S_Typ) and then not Fixed_Int);
2924 -- Check if we can determine at compile time whether Expr is in the
2925 -- range of the target type. Note that if S_Typ is within the bounds
2926 -- of Target_Typ then this must be the case. This check is meaningful
2927 -- only if this is not a conversion between integer and real types.
2929 if not Is_Unconstrained_Subscr_Ref
2930 and then Is_Discrete_Type (S_Typ) = Is_Discrete_Type (Target_Typ)
2932 (In_Subrange_Of (S_Typ, Target_Typ, Fixed_Int)
2934 Is_In_Range (Expr, Target_Typ,
2935 Assume_Valid => True,
2936 Fixed_Int => Fixed_Int,
2937 Int_Real => Int_Real))
2941 elsif Is_Out_Of_Range (Expr, Target_Typ,
2942 Assume_Valid => True,
2943 Fixed_Int => Fixed_Int,
2944 Int_Real => Int_Real)
2949 -- Floating-point case
2950 -- In the floating-point case, we only do range checks if the type is
2951 -- constrained. We definitely do NOT want range checks for unconstrained
2952 -- types, since we want to have infinities
2954 elsif Is_Floating_Point_Type (S_Typ) then
2956 -- Normally, we only do range checks if the type is constrained. We do
2957 -- NOT want range checks for unconstrained types, since we want to have
2958 -- infinities. Override this decision in Check_Float_Overflow mode.
2960 if Is_Constrained (S_Typ) or else Check_Float_Overflow then
2961 Enable_Range_Check (Expr);
2964 -- For all other cases we enable a range check unconditionally
2967 Enable_Range_Check (Expr);
2970 end Apply_Scalar_Range_Check;
2972 ----------------------------------
2973 -- Apply_Selected_Length_Checks --
2974 ----------------------------------
2976 procedure Apply_Selected_Length_Checks
2978 Target_Typ : Entity_Id;
2979 Source_Typ : Entity_Id;
2980 Do_Static : Boolean)
2983 R_Result : Check_Result;
2986 Loc : constant Source_Ptr := Sloc (Ck_Node);
2987 Checks_On : constant Boolean :=
2988 (not Index_Checks_Suppressed (Target_Typ))
2989 or else (not Length_Checks_Suppressed (Target_Typ));
2992 -- Note: this means that we lose some useful warnings if the expander
2993 -- is not active, and we also lose these warnings in SPARK mode ???
2995 if not Expander_Active then
3000 Selected_Length_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
3002 for J in 1 .. 2 loop
3003 R_Cno := R_Result (J);
3004 exit when No (R_Cno);
3006 -- A length check may mention an Itype which is attached to a
3007 -- subsequent node. At the top level in a package this can cause
3008 -- an order-of-elaboration problem, so we make sure that the itype
3009 -- is referenced now.
3011 if Ekind (Current_Scope) = E_Package
3012 and then Is_Compilation_Unit (Current_Scope)
3014 Ensure_Defined (Target_Typ, Ck_Node);
3016 if Present (Source_Typ) then
3017 Ensure_Defined (Source_Typ, Ck_Node);
3019 elsif Is_Itype (Etype (Ck_Node)) then
3020 Ensure_Defined (Etype (Ck_Node), Ck_Node);
3024 -- If the item is a conditional raise of constraint error, then have
3025 -- a look at what check is being performed and ???
3027 if Nkind (R_Cno) = N_Raise_Constraint_Error
3028 and then Present (Condition (R_Cno))
3030 Cond := Condition (R_Cno);
3032 -- Case where node does not now have a dynamic check
3034 if not Has_Dynamic_Length_Check (Ck_Node) then
3036 -- If checks are on, just insert the check
3039 Insert_Action (Ck_Node, R_Cno);
3041 if not Do_Static then
3042 Set_Has_Dynamic_Length_Check (Ck_Node);
3045 -- If checks are off, then analyze the length check after
3046 -- temporarily attaching it to the tree in case the relevant
3047 -- condition can be evaluated at compile time. We still want a
3048 -- compile time warning in this case.
3051 Set_Parent (R_Cno, Ck_Node);
3056 -- Output a warning if the condition is known to be True
3058 if Is_Entity_Name (Cond)
3059 and then Entity (Cond) = Standard_True
3061 Apply_Compile_Time_Constraint_Error
3062 (Ck_Node, "wrong length for array of}??",
3063 CE_Length_Check_Failed,
3067 -- If we were only doing a static check, or if checks are not
3068 -- on, then we want to delete the check, since it is not needed.
3069 -- We do this by replacing the if statement by a null statement
3071 elsif Do_Static or else not Checks_On then
3072 Remove_Warning_Messages (R_Cno);
3073 Rewrite (R_Cno, Make_Null_Statement (Loc));
3077 Install_Static_Check (R_Cno, Loc);
3080 end Apply_Selected_Length_Checks;
3082 ---------------------------------
3083 -- Apply_Selected_Range_Checks --
3084 ---------------------------------
3086 procedure Apply_Selected_Range_Checks
3088 Target_Typ : Entity_Id;
3089 Source_Typ : Entity_Id;
3090 Do_Static : Boolean)
3092 Loc : constant Source_Ptr := Sloc (Ck_Node);
3093 Checks_On : constant Boolean :=
3094 not Index_Checks_Suppressed (Target_Typ)
3096 not Range_Checks_Suppressed (Target_Typ);
3100 R_Result : Check_Result;
3103 if not Expander_Active or not Checks_On then
3108 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Empty);
3110 for J in 1 .. 2 loop
3111 R_Cno := R_Result (J);
3112 exit when No (R_Cno);
3114 -- The range check requires runtime evaluation. Depending on what its
3115 -- triggering condition is, the check may be converted into a compile
3116 -- time constraint check.
3118 if Nkind (R_Cno) = N_Raise_Constraint_Error
3119 and then Present (Condition (R_Cno))
3121 Cond := Condition (R_Cno);
3123 -- Insert the range check before the related context. Note that
3124 -- this action analyses the triggering condition.
3126 Insert_Action (Ck_Node, R_Cno);
3128 -- This old code doesn't make sense, why is the context flagged as
3129 -- requiring dynamic range checks now in the middle of generating
3132 if not Do_Static then
3133 Set_Has_Dynamic_Range_Check (Ck_Node);
3136 -- The triggering condition evaluates to True, the range check
3137 -- can be converted into a compile time constraint check.
3139 if Is_Entity_Name (Cond)
3140 and then Entity (Cond) = Standard_True
3142 -- Since an N_Range is technically not an expression, we have
3143 -- to set one of the bounds to C_E and then just flag the
3144 -- N_Range. The warning message will point to the lower bound
3145 -- and complain about a range, which seems OK.
3147 if Nkind (Ck_Node) = N_Range then
3148 Apply_Compile_Time_Constraint_Error
3149 (Low_Bound (Ck_Node),
3150 "static range out of bounds of}??",
3151 CE_Range_Check_Failed,
3155 Set_Raises_Constraint_Error (Ck_Node);
3158 Apply_Compile_Time_Constraint_Error
3160 "static value out of range of}??",
3161 CE_Range_Check_Failed,
3166 -- If we were only doing a static check, or if checks are not
3167 -- on, then we want to delete the check, since it is not needed.
3168 -- We do this by replacing the if statement by a null statement
3170 -- Why are we even generating checks if checks are turned off ???
3172 elsif Do_Static or else not Checks_On then
3173 Remove_Warning_Messages (R_Cno);
3174 Rewrite (R_Cno, Make_Null_Statement (Loc));
3177 -- The range check raises Constrant_Error explicitly
3180 Install_Static_Check (R_Cno, Loc);
3183 end Apply_Selected_Range_Checks;
3185 -------------------------------
3186 -- Apply_Static_Length_Check --
3187 -------------------------------
3189 procedure Apply_Static_Length_Check
3191 Target_Typ : Entity_Id;
3192 Source_Typ : Entity_Id := Empty)
3195 Apply_Selected_Length_Checks
3196 (Expr, Target_Typ, Source_Typ, Do_Static => True);
3197 end Apply_Static_Length_Check;
3199 -------------------------------------
3200 -- Apply_Subscript_Validity_Checks --
3201 -------------------------------------
3203 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id) is
3207 pragma Assert (Nkind (Expr) = N_Indexed_Component);
3209 -- Loop through subscripts
3211 Sub := First (Expressions (Expr));
3212 while Present (Sub) loop
3214 -- Check one subscript. Note that we do not worry about enumeration
3215 -- type with holes, since we will convert the value to a Pos value
3216 -- for the subscript, and that convert will do the necessary validity
3219 Ensure_Valid (Sub, Holes_OK => True);
3221 -- Move to next subscript
3225 end Apply_Subscript_Validity_Checks;
3227 ----------------------------------
3228 -- Apply_Type_Conversion_Checks --
3229 ----------------------------------
3231 procedure Apply_Type_Conversion_Checks (N : Node_Id) is
3232 Target_Type : constant Entity_Id := Etype (N);
3233 Target_Base : constant Entity_Id := Base_Type (Target_Type);
3234 Expr : constant Node_Id := Expression (N);
3236 Expr_Type : constant Entity_Id := Underlying_Type (Etype (Expr));
3237 -- Note: if Etype (Expr) is a private type without discriminants, its
3238 -- full view might have discriminants with defaults, so we need the
3239 -- full view here to retrieve the constraints.
3242 if Inside_A_Generic then
3245 -- Skip these checks if serious errors detected, there are some nasty
3246 -- situations of incomplete trees that blow things up.
3248 elsif Serious_Errors_Detected > 0 then
3251 -- Never generate discriminant checks for Unchecked_Union types
3253 elsif Present (Expr_Type)
3254 and then Is_Unchecked_Union (Expr_Type)
3258 -- Scalar type conversions of the form Target_Type (Expr) require a
3259 -- range check if we cannot be sure that Expr is in the base type of
3260 -- Target_Typ and also that Expr is in the range of Target_Typ. These
3261 -- are not quite the same condition from an implementation point of
3262 -- view, but clearly the second includes the first.
3264 elsif Is_Scalar_Type (Target_Type) then
3266 Conv_OK : constant Boolean := Conversion_OK (N);
3267 -- If the Conversion_OK flag on the type conversion is set and no
3268 -- floating-point type is involved in the type conversion then
3269 -- fixed-point values must be read as integral values.
3271 Float_To_Int : constant Boolean :=
3272 Is_Floating_Point_Type (Expr_Type)
3273 and then Is_Integer_Type (Target_Type);
3276 if not Overflow_Checks_Suppressed (Target_Base)
3277 and then not Overflow_Checks_Suppressed (Target_Type)
3279 In_Subrange_Of (Expr_Type, Target_Base, Fixed_Int => Conv_OK)
3280 and then not Float_To_Int
3282 Activate_Overflow_Check (N);
3285 if not Range_Checks_Suppressed (Target_Type)
3286 and then not Range_Checks_Suppressed (Expr_Type)
3288 if Float_To_Int then
3289 Apply_Float_Conversion_Check (Expr, Target_Type);
3291 Apply_Scalar_Range_Check
3292 (Expr, Target_Type, Fixed_Int => Conv_OK);
3294 -- If the target type has predicates, we need to indicate
3295 -- the need for a check, even if Determine_Range finds that
3296 -- the value is within bounds. This may be the case e.g for
3297 -- a division with a constant denominator.
3299 if Has_Predicates (Target_Type) then
3300 Enable_Range_Check (Expr);
3306 elsif Comes_From_Source (N)
3307 and then not Discriminant_Checks_Suppressed (Target_Type)
3308 and then Is_Record_Type (Target_Type)
3309 and then Is_Derived_Type (Target_Type)
3310 and then not Is_Tagged_Type (Target_Type)
3311 and then not Is_Constrained (Target_Type)
3312 and then Present (Stored_Constraint (Target_Type))
3314 -- An unconstrained derived type may have inherited discriminant.
3315 -- Build an actual discriminant constraint list using the stored
3316 -- constraint, to verify that the expression of the parent type
3317 -- satisfies the constraints imposed by the (unconstrained) derived
3318 -- type. This applies to value conversions, not to view conversions
3322 Loc : constant Source_Ptr := Sloc (N);
3324 Constraint : Elmt_Id;
3325 Discr_Value : Node_Id;
3328 New_Constraints : constant Elist_Id := New_Elmt_List;
3329 Old_Constraints : constant Elist_Id :=
3330 Discriminant_Constraint (Expr_Type);
3333 Constraint := First_Elmt (Stored_Constraint (Target_Type));
3334 while Present (Constraint) loop
3335 Discr_Value := Node (Constraint);
3337 if Is_Entity_Name (Discr_Value)
3338 and then Ekind (Entity (Discr_Value)) = E_Discriminant
3340 Discr := Corresponding_Discriminant (Entity (Discr_Value));
3343 and then Scope (Discr) = Base_Type (Expr_Type)
3345 -- Parent is constrained by new discriminant. Obtain
3346 -- Value of original discriminant in expression. If the
3347 -- new discriminant has been used to constrain more than
3348 -- one of the stored discriminants, this will provide the
3349 -- required consistency check.
3352 (Make_Selected_Component (Loc,
3354 Duplicate_Subexpr_No_Checks
3355 (Expr, Name_Req => True),
3357 Make_Identifier (Loc, Chars (Discr))),
3361 -- Discriminant of more remote ancestor ???
3366 -- Derived type definition has an explicit value for this
3367 -- stored discriminant.
3371 (Duplicate_Subexpr_No_Checks (Discr_Value),
3375 Next_Elmt (Constraint);
3378 -- Use the unconstrained expression type to retrieve the
3379 -- discriminants of the parent, and apply momentarily the
3380 -- discriminant constraint synthesized above.
3382 Set_Discriminant_Constraint (Expr_Type, New_Constraints);
3383 Cond := Build_Discriminant_Checks (Expr, Expr_Type);
3384 Set_Discriminant_Constraint (Expr_Type, Old_Constraints);
3387 Make_Raise_Constraint_Error (Loc,
3389 Reason => CE_Discriminant_Check_Failed));
3392 -- For arrays, checks are set now, but conversions are applied during
3393 -- expansion, to take into accounts changes of representation. The
3394 -- checks become range checks on the base type or length checks on the
3395 -- subtype, depending on whether the target type is unconstrained or
3396 -- constrained. Note that the range check is put on the expression of a
3397 -- type conversion, while the length check is put on the type conversion
3400 elsif Is_Array_Type (Target_Type) then
3401 if Is_Constrained (Target_Type) then
3402 Set_Do_Length_Check (N);
3404 Set_Do_Range_Check (Expr);
3407 end Apply_Type_Conversion_Checks;
3409 ----------------------------------------------
3410 -- Apply_Universal_Integer_Attribute_Checks --
3411 ----------------------------------------------
3413 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id) is
3414 Loc : constant Source_Ptr := Sloc (N);
3415 Typ : constant Entity_Id := Etype (N);
3418 if Inside_A_Generic then
3421 -- Nothing to do if checks are suppressed
3423 elsif Range_Checks_Suppressed (Typ)
3424 and then Overflow_Checks_Suppressed (Typ)
3428 -- Nothing to do if the attribute does not come from source. The
3429 -- internal attributes we generate of this type do not need checks,
3430 -- and furthermore the attempt to check them causes some circular
3431 -- elaboration orders when dealing with packed types.
3433 elsif not Comes_From_Source (N) then
3436 -- If the prefix is a selected component that depends on a discriminant
3437 -- the check may improperly expose a discriminant instead of using
3438 -- the bounds of the object itself. Set the type of the attribute to
3439 -- the base type of the context, so that a check will be imposed when
3440 -- needed (e.g. if the node appears as an index).
3442 elsif Nkind (Prefix (N)) = N_Selected_Component
3443 and then Ekind (Typ) = E_Signed_Integer_Subtype
3444 and then Depends_On_Discriminant (Scalar_Range (Typ))
3446 Set_Etype (N, Base_Type (Typ));
3448 -- Otherwise, replace the attribute node with a type conversion node
3449 -- whose expression is the attribute, retyped to universal integer, and
3450 -- whose subtype mark is the target type. The call to analyze this
3451 -- conversion will set range and overflow checks as required for proper
3452 -- detection of an out of range value.
3455 Set_Etype (N, Universal_Integer);
3456 Set_Analyzed (N, True);
3459 Make_Type_Conversion (Loc,
3460 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
3461 Expression => Relocate_Node (N)));
3463 Analyze_And_Resolve (N, Typ);
3466 end Apply_Universal_Integer_Attribute_Checks;
3468 -------------------------------------
3469 -- Atomic_Synchronization_Disabled --
3470 -------------------------------------
3472 -- Note: internally Disable/Enable_Atomic_Synchronization is implemented
3473 -- using a bogus check called Atomic_Synchronization. This is to make it
3474 -- more convenient to get exactly the same semantics as [Un]Suppress.
3476 function Atomic_Synchronization_Disabled (E : Entity_Id) return Boolean is
3478 -- If debug flag d.e is set, always return False, i.e. all atomic sync
3479 -- looks enabled, since it is never disabled.
3481 if Debug_Flag_Dot_E then
3484 -- If debug flag d.d is set then always return True, i.e. all atomic
3485 -- sync looks disabled, since it always tests True.
3487 elsif Debug_Flag_Dot_D then
3490 -- If entity present, then check result for that entity
3492 elsif Present (E) and then Checks_May_Be_Suppressed (E) then
3493 return Is_Check_Suppressed (E, Atomic_Synchronization);
3495 -- Otherwise result depends on current scope setting
3498 return Scope_Suppress.Suppress (Atomic_Synchronization);
3500 end Atomic_Synchronization_Disabled;
3502 -------------------------------
3503 -- Build_Discriminant_Checks --
3504 -------------------------------
3506 function Build_Discriminant_Checks
3508 T_Typ : Entity_Id) return Node_Id
3510 Loc : constant Source_Ptr := Sloc (N);
3513 Disc_Ent : Entity_Id;
3517 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id;
3519 ----------------------------------
3520 -- Aggregate_Discriminant_Value --
3521 ----------------------------------
3523 function Aggregate_Discriminant_Val (Disc : Entity_Id) return Node_Id is
3527 -- The aggregate has been normalized with named associations. We use
3528 -- the Chars field to locate the discriminant to take into account
3529 -- discriminants in derived types, which carry the same name as those
3532 Assoc := First (Component_Associations (N));
3533 while Present (Assoc) loop
3534 if Chars (First (Choices (Assoc))) = Chars (Disc) then
3535 return Expression (Assoc);
3541 -- Discriminant must have been found in the loop above
3543 raise Program_Error;
3544 end Aggregate_Discriminant_Val;
3546 -- Start of processing for Build_Discriminant_Checks
3549 -- Loop through discriminants evolving the condition
3552 Disc := First_Elmt (Discriminant_Constraint (T_Typ));
3554 -- For a fully private type, use the discriminants of the parent type
3556 if Is_Private_Type (T_Typ)
3557 and then No (Full_View (T_Typ))
3559 Disc_Ent := First_Discriminant (Etype (Base_Type (T_Typ)));
3561 Disc_Ent := First_Discriminant (T_Typ);
3564 while Present (Disc) loop
3565 Dval := Node (Disc);
3567 if Nkind (Dval) = N_Identifier
3568 and then Ekind (Entity (Dval)) = E_Discriminant
3570 Dval := New_Occurrence_Of (Discriminal (Entity (Dval)), Loc);
3572 Dval := Duplicate_Subexpr_No_Checks (Dval);
3575 -- If we have an Unchecked_Union node, we can infer the discriminants
3578 if Is_Unchecked_Union (Base_Type (T_Typ)) then
3580 Get_Discriminant_Value (
3581 First_Discriminant (T_Typ),
3583 Stored_Constraint (T_Typ)));
3585 elsif Nkind (N) = N_Aggregate then
3587 Duplicate_Subexpr_No_Checks
3588 (Aggregate_Discriminant_Val (Disc_Ent));
3592 Make_Selected_Component (Loc,
3594 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
3595 Selector_Name => Make_Identifier (Loc, Chars (Disc_Ent)));
3597 Set_Is_In_Discriminant_Check (Dref);
3600 Evolve_Or_Else (Cond,
3603 Right_Opnd => Dval));
3606 Next_Discriminant (Disc_Ent);
3610 end Build_Discriminant_Checks;
3616 function Check_Needed (Nod : Node_Id; Check : Check_Type) return Boolean is
3623 function Left_Expression (Op : Node_Id) return Node_Id;
3624 -- Return the relevant expression from the left operand of the given
3625 -- short circuit form: this is LO itself, except if LO is a qualified
3626 -- expression, a type conversion, or an expression with actions, in
3627 -- which case this is Left_Expression (Expression (LO)).
3629 ---------------------
3630 -- Left_Expression --
3631 ---------------------
3633 function Left_Expression (Op : Node_Id) return Node_Id is
3634 LE : Node_Id := Left_Opnd (Op);
3636 while Nkind_In (LE, N_Qualified_Expression,
3638 N_Expression_With_Actions)
3640 LE := Expression (LE);
3644 end Left_Expression;
3646 -- Start of processing for Check_Needed
3649 -- Always check if not simple entity
3651 if Nkind (Nod) not in N_Has_Entity
3652 or else not Comes_From_Source (Nod)
3657 -- Look up tree for short circuit
3664 -- Done if out of subexpression (note that we allow generated stuff
3665 -- such as itype declarations in this context, to keep the loop going
3666 -- since we may well have generated such stuff in complex situations.
3667 -- Also done if no parent (probably an error condition, but no point
3668 -- in behaving nasty if we find it).
3671 or else (K not in N_Subexpr and then Comes_From_Source (P))
3675 -- Or/Or Else case, where test is part of the right operand, or is
3676 -- part of one of the actions associated with the right operand, and
3677 -- the left operand is an equality test.
3679 elsif K = N_Op_Or then
3680 exit when N = Right_Opnd (P)
3681 and then Nkind (Left_Expression (P)) = N_Op_Eq;
3683 elsif K = N_Or_Else then
3684 exit when (N = Right_Opnd (P)
3687 and then List_Containing (N) = Actions (P)))
3688 and then Nkind (Left_Expression (P)) = N_Op_Eq;
3690 -- Similar test for the And/And then case, where the left operand
3691 -- is an inequality test.
3693 elsif K = N_Op_And then
3694 exit when N = Right_Opnd (P)
3695 and then Nkind (Left_Expression (P)) = N_Op_Ne;
3697 elsif K = N_And_Then then
3698 exit when (N = Right_Opnd (P)
3701 and then List_Containing (N) = Actions (P)))
3702 and then Nkind (Left_Expression (P)) = N_Op_Ne;
3708 -- If we fall through the loop, then we have a conditional with an
3709 -- appropriate test as its left operand, so look further.
3711 L := Left_Expression (P);
3713 -- L is an "=" or "/=" operator: extract its operands
3715 R := Right_Opnd (L);
3718 -- Left operand of test must match original variable
3720 if Nkind (L) not in N_Has_Entity or else Entity (L) /= Entity (Nod) then
3724 -- Right operand of test must be key value (zero or null)
3727 when Access_Check =>
3728 if not Known_Null (R) then
3732 when Division_Check =>
3733 if not Compile_Time_Known_Value (R)
3734 or else Expr_Value (R) /= Uint_0
3740 raise Program_Error;
3743 -- Here we have the optimizable case, warn if not short-circuited
3745 if K = N_Op_And or else K = N_Op_Or then
3746 Error_Msg_Warn := SPARK_Mode /= On;
3749 when Access_Check =>
3750 if GNATprove_Mode then
3752 ("Constraint_Error might have been raised (access check)",
3756 ("Constraint_Error may be raised (access check)??",
3760 when Division_Check =>
3761 if GNATprove_Mode then
3763 ("Constraint_Error might have been raised (zero divide)",
3767 ("Constraint_Error may be raised (zero divide)??",
3772 raise Program_Error;
3775 if K = N_Op_And then
3776 Error_Msg_N -- CODEFIX
3777 ("use `AND THEN` instead of AND??", P);
3779 Error_Msg_N -- CODEFIX
3780 ("use `OR ELSE` instead of OR??", P);
3783 -- If not short-circuited, we need the check
3787 -- If short-circuited, we can omit the check
3794 -----------------------------------
3795 -- Check_Valid_Lvalue_Subscripts --
3796 -----------------------------------
3798 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id) is
3800 -- Skip this if range checks are suppressed
3802 if Range_Checks_Suppressed (Etype (Expr)) then
3805 -- Only do this check for expressions that come from source. We assume
3806 -- that expander generated assignments explicitly include any necessary
3807 -- checks. Note that this is not just an optimization, it avoids
3808 -- infinite recursions.
3810 elsif not Comes_From_Source (Expr) then
3813 -- For a selected component, check the prefix
3815 elsif Nkind (Expr) = N_Selected_Component then
3816 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
3819 -- Case of indexed component
3821 elsif Nkind (Expr) = N_Indexed_Component then
3822 Apply_Subscript_Validity_Checks (Expr);
3824 -- Prefix may itself be or contain an indexed component, and these
3825 -- subscripts need checking as well.
3827 Check_Valid_Lvalue_Subscripts (Prefix (Expr));
3829 end Check_Valid_Lvalue_Subscripts;
3831 ----------------------------------
3832 -- Null_Exclusion_Static_Checks --
3833 ----------------------------------
3835 procedure Null_Exclusion_Static_Checks (N : Node_Id) is
3836 Error_Node : Node_Id;
3838 Has_Null : constant Boolean := Has_Null_Exclusion (N);
3839 K : constant Node_Kind := Nkind (N);
3844 (Nkind_In (K, N_Component_Declaration,
3845 N_Discriminant_Specification,
3846 N_Function_Specification,
3847 N_Object_Declaration,
3848 N_Parameter_Specification));
3850 if K = N_Function_Specification then
3851 Typ := Etype (Defining_Entity (N));
3853 Typ := Etype (Defining_Identifier (N));
3857 when N_Component_Declaration =>
3858 if Present (Access_Definition (Component_Definition (N))) then
3859 Error_Node := Component_Definition (N);
3861 Error_Node := Subtype_Indication (Component_Definition (N));
3864 when N_Discriminant_Specification =>
3865 Error_Node := Discriminant_Type (N);
3867 when N_Function_Specification =>
3868 Error_Node := Result_Definition (N);
3870 when N_Object_Declaration =>
3871 Error_Node := Object_Definition (N);
3873 when N_Parameter_Specification =>
3874 Error_Node := Parameter_Type (N);
3877 raise Program_Error;
3882 -- Enforce legality rule 3.10 (13): A null exclusion can only be
3883 -- applied to an access [sub]type.
3885 if not Is_Access_Type (Typ) then
3887 ("`NOT NULL` allowed only for an access type", Error_Node);
3889 -- Enforce legality rule RM 3.10(14/1): A null exclusion can only
3890 -- be applied to a [sub]type that does not exclude null already.
3892 elsif Can_Never_Be_Null (Typ)
3893 and then Comes_From_Source (Typ)
3896 ("`NOT NULL` not allowed (& already excludes null)",
3901 -- Check that null-excluding objects are always initialized, except for
3902 -- deferred constants, for which the expression will appear in the full
3905 if K = N_Object_Declaration
3906 and then No (Expression (N))
3907 and then not Constant_Present (N)
3908 and then not No_Initialization (N)
3910 -- Add an expression that assigns null. This node is needed by
3911 -- Apply_Compile_Time_Constraint_Error, which will replace this with
3912 -- a Constraint_Error node.
3914 Set_Expression (N, Make_Null (Sloc (N)));
3915 Set_Etype (Expression (N), Etype (Defining_Identifier (N)));
3917 Apply_Compile_Time_Constraint_Error
3918 (N => Expression (N),
3920 "(Ada 2005) null-excluding objects must be initialized??",
3921 Reason => CE_Null_Not_Allowed);
3924 -- Check that a null-excluding component, formal or object is not being
3925 -- assigned a null value. Otherwise generate a warning message and
3926 -- replace Expression (N) by an N_Constraint_Error node.
3928 if K /= N_Function_Specification then
3929 Expr := Expression (N);
3931 if Present (Expr) and then Known_Null (Expr) then
3933 when N_Component_Declaration |
3934 N_Discriminant_Specification =>
3935 Apply_Compile_Time_Constraint_Error
3937 Msg => "(Ada 2005) null not allowed "
3938 & "in null-excluding components??",
3939 Reason => CE_Null_Not_Allowed);
3941 when N_Object_Declaration =>
3942 Apply_Compile_Time_Constraint_Error
3944 Msg => "(Ada 2005) null not allowed "
3945 & "in null-excluding objects??",
3946 Reason => CE_Null_Not_Allowed);
3948 when N_Parameter_Specification =>
3949 Apply_Compile_Time_Constraint_Error
3951 Msg => "(Ada 2005) null not allowed "
3952 & "in null-excluding formals??",
3953 Reason => CE_Null_Not_Allowed);
3960 end Null_Exclusion_Static_Checks;
3962 ----------------------------------
3963 -- Conditional_Statements_Begin --
3964 ----------------------------------
3966 procedure Conditional_Statements_Begin is
3968 Saved_Checks_TOS := Saved_Checks_TOS + 1;
3970 -- If stack overflows, kill all checks, that way we know to simply reset
3971 -- the number of saved checks to zero on return. This should never occur
3974 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
3977 -- In the normal case, we just make a new stack entry saving the current
3978 -- number of saved checks for a later restore.
3981 Saved_Checks_Stack (Saved_Checks_TOS) := Num_Saved_Checks;
3983 if Debug_Flag_CC then
3984 w ("Conditional_Statements_Begin: Num_Saved_Checks = ",
3988 end Conditional_Statements_Begin;
3990 --------------------------------
3991 -- Conditional_Statements_End --
3992 --------------------------------
3994 procedure Conditional_Statements_End is
3996 pragma Assert (Saved_Checks_TOS > 0);
3998 -- If the saved checks stack overflowed, then we killed all checks, so
3999 -- setting the number of saved checks back to zero is correct. This
4000 -- should never occur in practice.
4002 if Saved_Checks_TOS > Saved_Checks_Stack'Last then
4003 Num_Saved_Checks := 0;
4005 -- In the normal case, restore the number of saved checks from the top
4009 Num_Saved_Checks := Saved_Checks_Stack (Saved_Checks_TOS);
4011 if Debug_Flag_CC then
4012 w ("Conditional_Statements_End: Num_Saved_Checks = ",
4017 Saved_Checks_TOS := Saved_Checks_TOS - 1;
4018 end Conditional_Statements_End;
4020 -------------------------
4021 -- Convert_From_Bignum --
4022 -------------------------
4024 function Convert_From_Bignum (N : Node_Id) return Node_Id is
4025 Loc : constant Source_Ptr := Sloc (N);
4028 pragma Assert (Is_RTE (Etype (N), RE_Bignum));
4030 -- Construct call From Bignum
4033 Make_Function_Call (Loc,
4035 New_Occurrence_Of (RTE (RE_From_Bignum), Loc),
4036 Parameter_Associations => New_List (Relocate_Node (N)));
4037 end Convert_From_Bignum;
4039 -----------------------
4040 -- Convert_To_Bignum --
4041 -----------------------
4043 function Convert_To_Bignum (N : Node_Id) return Node_Id is
4044 Loc : constant Source_Ptr := Sloc (N);
4047 -- Nothing to do if Bignum already except call Relocate_Node
4049 if Is_RTE (Etype (N), RE_Bignum) then
4050 return Relocate_Node (N);
4052 -- Otherwise construct call to To_Bignum, converting the operand to the
4053 -- required Long_Long_Integer form.
4056 pragma Assert (Is_Signed_Integer_Type (Etype (N)));
4058 Make_Function_Call (Loc,
4060 New_Occurrence_Of (RTE (RE_To_Bignum), Loc),
4061 Parameter_Associations => New_List (
4062 Convert_To (Standard_Long_Long_Integer, Relocate_Node (N))));
4064 end Convert_To_Bignum;
4066 ---------------------
4067 -- Determine_Range --
4068 ---------------------
4070 Cache_Size : constant := 2 ** 10;
4071 type Cache_Index is range 0 .. Cache_Size - 1;
4072 -- Determine size of below cache (power of 2 is more efficient)
4074 Determine_Range_Cache_N : array (Cache_Index) of Node_Id;
4075 Determine_Range_Cache_V : array (Cache_Index) of Boolean;
4076 Determine_Range_Cache_Lo : array (Cache_Index) of Uint;
4077 Determine_Range_Cache_Hi : array (Cache_Index) of Uint;
4078 -- The above arrays are used to implement a small direct cache for
4079 -- Determine_Range calls. Because of the way Determine_Range recursively
4080 -- traces subexpressions, and because overflow checking calls the routine
4081 -- on the way up the tree, a quadratic behavior can otherwise be
4082 -- encountered in large expressions. The cache entry for node N is stored
4083 -- in the (N mod Cache_Size) entry, and can be validated by checking the
4084 -- actual node value stored there. The Range_Cache_V array records the
4085 -- setting of Assume_Valid for the cache entry.
4087 procedure Determine_Range
4092 Assume_Valid : Boolean := False)
4094 Typ : Entity_Id := Etype (N);
4095 -- Type to use, may get reset to base type for possibly invalid entity
4099 -- Lo and Hi bounds of left operand
4103 -- Lo and Hi bounds of right (or only) operand
4106 -- Temp variable used to hold a bound node
4109 -- High bound of base type of expression
4113 -- Refined values for low and high bounds, after tightening
4116 -- Used in lower level calls to indicate if call succeeded
4118 Cindex : Cache_Index;
4119 -- Used to search cache
4124 function OK_Operands return Boolean;
4125 -- Used for binary operators. Determines the ranges of the left and
4126 -- right operands, and if they are both OK, returns True, and puts
4127 -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left.
4133 function OK_Operands return Boolean is
4136 (Left_Opnd (N), OK1, Lo_Left, Hi_Left, Assume_Valid);
4143 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4147 -- Start of processing for Determine_Range
4150 -- Prevent junk warnings by initializing range variables
4157 -- For temporary constants internally generated to remove side effects
4158 -- we must use the corresponding expression to determine the range of
4159 -- the expression. But note that the expander can also generate
4160 -- constants in other cases, including deferred constants.
4162 if Is_Entity_Name (N)
4163 and then Nkind (Parent (Entity (N))) = N_Object_Declaration
4164 and then Ekind (Entity (N)) = E_Constant
4165 and then Is_Internal_Name (Chars (Entity (N)))
4167 if Present (Expression (Parent (Entity (N)))) then
4169 (Expression (Parent (Entity (N))), OK, Lo, Hi, Assume_Valid);
4171 elsif Present (Full_View (Entity (N))) then
4173 (Expression (Parent (Full_View (Entity (N)))),
4174 OK, Lo, Hi, Assume_Valid);
4182 -- If type is not defined, we can't determine its range
4186 -- We don't deal with anything except discrete types
4188 or else not Is_Discrete_Type (Typ)
4190 -- Ignore type for which an error has been posted, since range in
4191 -- this case may well be a bogosity deriving from the error. Also
4192 -- ignore if error posted on the reference node.
4194 or else Error_Posted (N) or else Error_Posted (Typ)
4200 -- For all other cases, we can determine the range
4204 -- If value is compile time known, then the possible range is the one
4205 -- value that we know this expression definitely has.
4207 if Compile_Time_Known_Value (N) then
4208 Lo := Expr_Value (N);
4213 -- Return if already in the cache
4215 Cindex := Cache_Index (N mod Cache_Size);
4217 if Determine_Range_Cache_N (Cindex) = N
4219 Determine_Range_Cache_V (Cindex) = Assume_Valid
4221 Lo := Determine_Range_Cache_Lo (Cindex);
4222 Hi := Determine_Range_Cache_Hi (Cindex);
4226 -- Otherwise, start by finding the bounds of the type of the expression,
4227 -- the value cannot be outside this range (if it is, then we have an
4228 -- overflow situation, which is a separate check, we are talking here
4229 -- only about the expression value).
4231 -- First a check, never try to find the bounds of a generic type, since
4232 -- these bounds are always junk values, and it is only valid to look at
4233 -- the bounds in an instance.
4235 if Is_Generic_Type (Typ) then
4240 -- First step, change to use base type unless we know the value is valid
4242 if (Is_Entity_Name (N) and then Is_Known_Valid (Entity (N)))
4243 or else Assume_No_Invalid_Values
4244 or else Assume_Valid
4248 Typ := Underlying_Type (Base_Type (Typ));
4251 -- Retrieve the base type. Handle the case where the base type is a
4252 -- private enumeration type.
4254 Btyp := Base_Type (Typ);
4256 if Is_Private_Type (Btyp) and then Present (Full_View (Btyp)) then
4257 Btyp := Full_View (Btyp);
4260 -- We use the actual bound unless it is dynamic, in which case use the
4261 -- corresponding base type bound if possible. If we can't get a bound
4262 -- then we figure we can't determine the range (a peculiar case, that
4263 -- perhaps cannot happen, but there is no point in bombing in this
4264 -- optimization circuit.
4266 -- First the low bound
4268 Bound := Type_Low_Bound (Typ);
4270 if Compile_Time_Known_Value (Bound) then
4271 Lo := Expr_Value (Bound);
4273 elsif Compile_Time_Known_Value (Type_Low_Bound (Btyp)) then
4274 Lo := Expr_Value (Type_Low_Bound (Btyp));
4281 -- Now the high bound
4283 Bound := Type_High_Bound (Typ);
4285 -- We need the high bound of the base type later on, and this should
4286 -- always be compile time known. Again, it is not clear that this
4287 -- can ever be false, but no point in bombing.
4289 if Compile_Time_Known_Value (Type_High_Bound (Btyp)) then
4290 Hbound := Expr_Value (Type_High_Bound (Btyp));
4298 -- If we have a static subtype, then that may have a tighter bound so
4299 -- use the upper bound of the subtype instead in this case.
4301 if Compile_Time_Known_Value (Bound) then
4302 Hi := Expr_Value (Bound);
4305 -- We may be able to refine this value in certain situations. If any
4306 -- refinement is possible, then Lor and Hir are set to possibly tighter
4307 -- bounds, and OK1 is set to True.
4311 -- For unary plus, result is limited by range of operand
4315 (Right_Opnd (N), OK1, Lor, Hir, Assume_Valid);
4317 -- For unary minus, determine range of operand, and negate it
4321 (Right_Opnd (N), OK1, Lo_Right, Hi_Right, Assume_Valid);
4328 -- For binary addition, get range of each operand and do the
4329 -- addition to get the result range.
4333 Lor := Lo_Left + Lo_Right;
4334 Hir := Hi_Left + Hi_Right;
4337 -- Division is tricky. The only case we consider is where the right
4338 -- operand is a positive constant, and in this case we simply divide
4339 -- the bounds of the left operand
4343 if Lo_Right = Hi_Right
4344 and then Lo_Right > 0
4346 Lor := Lo_Left / Lo_Right;
4347 Hir := Hi_Left / Lo_Right;
4353 -- For binary subtraction, get range of each operand and do the worst
4354 -- case subtraction to get the result range.
4356 when N_Op_Subtract =>
4358 Lor := Lo_Left - Hi_Right;
4359 Hir := Hi_Left - Lo_Right;
4362 -- For MOD, if right operand is a positive constant, then result must
4363 -- be in the allowable range of mod results.
4367 if Lo_Right = Hi_Right
4368 and then Lo_Right /= 0
4370 if Lo_Right > 0 then
4372 Hir := Lo_Right - 1;
4374 else -- Lo_Right < 0
4375 Lor := Lo_Right + 1;
4384 -- For REM, if right operand is a positive constant, then result must
4385 -- be in the allowable range of mod results.
4389 if Lo_Right = Hi_Right
4390 and then Lo_Right /= 0
4393 Dval : constant Uint := (abs Lo_Right) - 1;
4396 -- The sign of the result depends on the sign of the
4397 -- dividend (but not on the sign of the divisor, hence
4398 -- the abs operation above).
4418 -- Attribute reference cases
4420 when N_Attribute_Reference =>
4421 case Attribute_Name (N) is
4423 -- For Pos/Val attributes, we can refine the range using the
4424 -- possible range of values of the attribute expression.
4426 when Name_Pos | Name_Val =>
4428 (First (Expressions (N)), OK1, Lor, Hir, Assume_Valid);
4430 -- For Length attribute, use the bounds of the corresponding
4431 -- index type to refine the range.
4435 Atyp : Entity_Id := Etype (Prefix (N));
4443 if Is_Access_Type (Atyp) then
4444 Atyp := Designated_Type (Atyp);
4447 -- For string literal, we know exact value
4449 if Ekind (Atyp) = E_String_Literal_Subtype then
4451 Lo := String_Literal_Length (Atyp);
4452 Hi := String_Literal_Length (Atyp);
4456 -- Otherwise check for expression given
4458 if No (Expressions (N)) then
4462 UI_To_Int (Expr_Value (First (Expressions (N))));
4465 Indx := First_Index (Atyp);
4466 for J in 2 .. Inum loop
4467 Indx := Next_Index (Indx);
4470 -- If the index type is a formal type or derived from
4471 -- one, the bounds are not static.
4473 if Is_Generic_Type (Root_Type (Etype (Indx))) then
4479 (Type_Low_Bound (Etype (Indx)), OK1, LL, LU,
4484 (Type_High_Bound (Etype (Indx)), OK1, UL, UU,
4489 -- The maximum value for Length is the biggest
4490 -- possible gap between the values of the bounds.
4491 -- But of course, this value cannot be negative.
4493 Hir := UI_Max (Uint_0, UU - LL + 1);
4495 -- For constrained arrays, the minimum value for
4496 -- Length is taken from the actual value of the
4497 -- bounds, since the index will be exactly of this
4500 if Is_Constrained (Atyp) then
4501 Lor := UI_Max (Uint_0, UL - LU + 1);
4503 -- For an unconstrained array, the minimum value
4504 -- for length is always zero.
4513 -- No special handling for other attributes
4514 -- Probably more opportunities exist here???
4521 -- For type conversion from one discrete type to another, we can
4522 -- refine the range using the converted value.
4524 when N_Type_Conversion =>
4525 Determine_Range (Expression (N), OK1, Lor, Hir, Assume_Valid);
4527 -- Nothing special to do for all other expression kinds
4535 -- At this stage, if OK1 is true, then we know that the actual result of
4536 -- the computed expression is in the range Lor .. Hir. We can use this
4537 -- to restrict the possible range of results.
4541 -- If the refined value of the low bound is greater than the type
4542 -- high bound, then reset it to the more restrictive value. However,
4543 -- we do NOT do this for the case of a modular type where the
4544 -- possible upper bound on the value is above the base type high
4545 -- bound, because that means the result could wrap.
4548 and then not (Is_Modular_Integer_Type (Typ) and then Hir > Hbound)
4553 -- Similarly, if the refined value of the high bound is less than the
4554 -- value so far, then reset it to the more restrictive value. Again,
4555 -- we do not do this if the refined low bound is negative for a
4556 -- modular type, since this would wrap.
4559 and then not (Is_Modular_Integer_Type (Typ) and then Lor < Uint_0)
4565 -- Set cache entry for future call and we are all done
4567 Determine_Range_Cache_N (Cindex) := N;
4568 Determine_Range_Cache_V (Cindex) := Assume_Valid;
4569 Determine_Range_Cache_Lo (Cindex) := Lo;
4570 Determine_Range_Cache_Hi (Cindex) := Hi;
4573 -- If any exception occurs, it means that we have some bug in the compiler,
4574 -- possibly triggered by a previous error, or by some unforeseen peculiar
4575 -- occurrence. However, this is only an optimization attempt, so there is
4576 -- really no point in crashing the compiler. Instead we just decide, too
4577 -- bad, we can't figure out a range in this case after all.
4582 -- Debug flag K disables this behavior (useful for debugging)
4584 if Debug_Flag_K then
4592 end Determine_Range;
4594 ------------------------------------
4595 -- Discriminant_Checks_Suppressed --
4596 ------------------------------------
4598 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean is
4601 if Is_Unchecked_Union (E) then
4603 elsif Checks_May_Be_Suppressed (E) then
4604 return Is_Check_Suppressed (E, Discriminant_Check);
4608 return Scope_Suppress.Suppress (Discriminant_Check);
4609 end Discriminant_Checks_Suppressed;
4611 --------------------------------
4612 -- Division_Checks_Suppressed --
4613 --------------------------------
4615 function Division_Checks_Suppressed (E : Entity_Id) return Boolean is
4617 if Present (E) and then Checks_May_Be_Suppressed (E) then
4618 return Is_Check_Suppressed (E, Division_Check);
4620 return Scope_Suppress.Suppress (Division_Check);
4622 end Division_Checks_Suppressed;
4624 --------------------------------------
4625 -- Duplicated_Tag_Checks_Suppressed --
4626 --------------------------------------
4628 function Duplicated_Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
4630 if Present (E) and then Checks_May_Be_Suppressed (E) then
4631 return Is_Check_Suppressed (E, Duplicated_Tag_Check);
4633 return Scope_Suppress.Suppress (Duplicated_Tag_Check);
4635 end Duplicated_Tag_Checks_Suppressed;
4637 -----------------------------------
4638 -- Elaboration_Checks_Suppressed --
4639 -----------------------------------
4641 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean is
4643 -- The complication in this routine is that if we are in the dynamic
4644 -- model of elaboration, we also check All_Checks, since All_Checks
4645 -- does not set Elaboration_Check explicitly.
4648 if Kill_Elaboration_Checks (E) then
4651 elsif Checks_May_Be_Suppressed (E) then
4652 if Is_Check_Suppressed (E, Elaboration_Check) then
4654 elsif Dynamic_Elaboration_Checks then
4655 return Is_Check_Suppressed (E, All_Checks);
4662 if Scope_Suppress.Suppress (Elaboration_Check) then
4664 elsif Dynamic_Elaboration_Checks then
4665 return Scope_Suppress.Suppress (All_Checks);
4669 end Elaboration_Checks_Suppressed;
4671 ---------------------------
4672 -- Enable_Overflow_Check --
4673 ---------------------------
4675 procedure Enable_Overflow_Check (N : Node_Id) is
4676 Typ : constant Entity_Id := Base_Type (Etype (N));
4677 Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
4686 if Debug_Flag_CC then
4687 w ("Enable_Overflow_Check for node ", Int (N));
4688 Write_Str (" Source location = ");
4693 -- No check if overflow checks suppressed for type of node
4695 if Overflow_Checks_Suppressed (Etype (N)) then
4698 -- Nothing to do for unsigned integer types, which do not overflow
4700 elsif Is_Modular_Integer_Type (Typ) then
4704 -- This is the point at which processing for STRICT mode diverges
4705 -- from processing for MINIMIZED/ELIMINATED modes. This divergence is
4706 -- probably more extreme that it needs to be, but what is going on here
4707 -- is that when we introduced MINIMIZED/ELIMINATED modes, we wanted
4708 -- to leave the processing for STRICT mode untouched. There were
4709 -- two reasons for this. First it avoided any incompatible change of
4710 -- behavior. Second, it guaranteed that STRICT mode continued to be
4713 -- The big difference is that in STRICT mode there is a fair amount of
4714 -- circuitry to try to avoid setting the Do_Overflow_Check flag if we
4715 -- know that no check is needed. We skip all that in the two new modes,
4716 -- since really overflow checking happens over a whole subtree, and we
4717 -- do the corresponding optimizations later on when applying the checks.
4719 if Mode in Minimized_Or_Eliminated then
4720 if not (Overflow_Checks_Suppressed (Etype (N)))
4721 and then not (Is_Entity_Name (N)
4722 and then Overflow_Checks_Suppressed (Entity (N)))
4724 Activate_Overflow_Check (N);
4727 if Debug_Flag_CC then
4728 w ("Minimized/Eliminated mode");
4734 -- Remainder of processing is for STRICT case, and is unchanged from
4735 -- earlier versions preceding the addition of MINIMIZED/ELIMINATED.
4737 -- Nothing to do if the range of the result is known OK. We skip this
4738 -- for conversions, since the caller already did the check, and in any
4739 -- case the condition for deleting the check for a type conversion is
4742 if Nkind (N) /= N_Type_Conversion then
4743 Determine_Range (N, OK, Lo, Hi, Assume_Valid => True);
4745 -- Note in the test below that we assume that the range is not OK
4746 -- if a bound of the range is equal to that of the type. That's not
4747 -- quite accurate but we do this for the following reasons:
4749 -- a) The way that Determine_Range works, it will typically report
4750 -- the bounds of the value as being equal to the bounds of the
4751 -- type, because it either can't tell anything more precise, or
4752 -- does not think it is worth the effort to be more precise.
4754 -- b) It is very unusual to have a situation in which this would
4755 -- generate an unnecessary overflow check (an example would be
4756 -- a subtype with a range 0 .. Integer'Last - 1 to which the
4757 -- literal value one is added).
4759 -- c) The alternative is a lot of special casing in this routine
4760 -- which would partially duplicate Determine_Range processing.
4763 and then Lo > Expr_Value (Type_Low_Bound (Typ))
4764 and then Hi < Expr_Value (Type_High_Bound (Typ))
4766 if Debug_Flag_CC then
4767 w ("No overflow check required");
4774 -- If not in optimizing mode, set flag and we are done. We are also done
4775 -- (and just set the flag) if the type is not a discrete type, since it
4776 -- is not worth the effort to eliminate checks for other than discrete
4777 -- types. In addition, we take this same path if we have stored the
4778 -- maximum number of checks possible already (a very unlikely situation,
4779 -- but we do not want to blow up).
4781 if Optimization_Level = 0
4782 or else not Is_Discrete_Type (Etype (N))
4783 or else Num_Saved_Checks = Saved_Checks'Last
4785 Activate_Overflow_Check (N);
4787 if Debug_Flag_CC then
4788 w ("Optimization off");
4794 -- Otherwise evaluate and check the expression
4799 Target_Type => Empty,
4805 if Debug_Flag_CC then
4806 w ("Called Find_Check");
4810 w (" Check_Num = ", Chk);
4811 w (" Ent = ", Int (Ent));
4812 Write_Str (" Ofs = ");
4817 -- If check is not of form to optimize, then set flag and we are done
4820 Activate_Overflow_Check (N);
4824 -- If check is already performed, then return without setting flag
4827 if Debug_Flag_CC then
4828 w ("Check suppressed!");
4834 -- Here we will make a new entry for the new check
4836 Activate_Overflow_Check (N);
4837 Num_Saved_Checks := Num_Saved_Checks + 1;
4838 Saved_Checks (Num_Saved_Checks) :=
4843 Target_Type => Empty);
4845 if Debug_Flag_CC then
4846 w ("Make new entry, check number = ", Num_Saved_Checks);
4847 w (" Entity = ", Int (Ent));
4848 Write_Str (" Offset = ");
4850 w (" Check_Type = O");
4851 w (" Target_Type = Empty");
4854 -- If we get an exception, then something went wrong, probably because of
4855 -- an error in the structure of the tree due to an incorrect program. Or
4856 -- it may be a bug in the optimization circuit. In either case the safest
4857 -- thing is simply to set the check flag unconditionally.
4861 Activate_Overflow_Check (N);
4863 if Debug_Flag_CC then
4864 w (" exception occurred, overflow flag set");
4868 end Enable_Overflow_Check;
4870 ------------------------
4871 -- Enable_Range_Check --
4872 ------------------------
4874 procedure Enable_Range_Check (N : Node_Id) is
4883 -- Return if unchecked type conversion with range check killed. In this
4884 -- case we never set the flag (that's what Kill_Range_Check is about).
4886 if Nkind (N) = N_Unchecked_Type_Conversion
4887 and then Kill_Range_Check (N)
4892 -- Do not set range check flag if parent is assignment statement or
4893 -- object declaration with Suppress_Assignment_Checks flag set
4895 if Nkind_In (Parent (N), N_Assignment_Statement, N_Object_Declaration)
4896 and then Suppress_Assignment_Checks (Parent (N))
4901 -- Check for various cases where we should suppress the range check
4903 -- No check if range checks suppressed for type of node
4905 if Present (Etype (N)) and then Range_Checks_Suppressed (Etype (N)) then
4908 -- No check if node is an entity name, and range checks are suppressed
4909 -- for this entity, or for the type of this entity.
4911 elsif Is_Entity_Name (N)
4912 and then (Range_Checks_Suppressed (Entity (N))
4913 or else Range_Checks_Suppressed (Etype (Entity (N))))
4917 -- No checks if index of array, and index checks are suppressed for
4918 -- the array object or the type of the array.
4920 elsif Nkind (Parent (N)) = N_Indexed_Component then
4922 Pref : constant Node_Id := Prefix (Parent (N));
4924 if Is_Entity_Name (Pref)
4925 and then Index_Checks_Suppressed (Entity (Pref))
4928 elsif Index_Checks_Suppressed (Etype (Pref)) then
4934 -- Debug trace output
4936 if Debug_Flag_CC then
4937 w ("Enable_Range_Check for node ", Int (N));
4938 Write_Str (" Source location = ");
4943 -- If not in optimizing mode, set flag and we are done. We are also done
4944 -- (and just set the flag) if the type is not a discrete type, since it
4945 -- is not worth the effort to eliminate checks for other than discrete
4946 -- types. In addition, we take this same path if we have stored the
4947 -- maximum number of checks possible already (a very unlikely situation,
4948 -- but we do not want to blow up).
4950 if Optimization_Level = 0
4951 or else No (Etype (N))
4952 or else not Is_Discrete_Type (Etype (N))
4953 or else Num_Saved_Checks = Saved_Checks'Last
4955 Activate_Range_Check (N);
4957 if Debug_Flag_CC then
4958 w ("Optimization off");
4964 -- Otherwise find out the target type
4968 -- For assignment, use left side subtype
4970 if Nkind (P) = N_Assignment_Statement
4971 and then Expression (P) = N
4973 Ttyp := Etype (Name (P));
4975 -- For indexed component, use subscript subtype
4977 elsif Nkind (P) = N_Indexed_Component then
4984 Atyp := Etype (Prefix (P));
4986 if Is_Access_Type (Atyp) then
4987 Atyp := Designated_Type (Atyp);
4989 -- If the prefix is an access to an unconstrained array,
4990 -- perform check unconditionally: it depends on the bounds of
4991 -- an object and we cannot currently recognize whether the test
4992 -- may be redundant.
4994 if not Is_Constrained (Atyp) then
4995 Activate_Range_Check (N);
4999 -- Ditto if the prefix is an explicit dereference whose designated
5000 -- type is unconstrained.
5002 elsif Nkind (Prefix (P)) = N_Explicit_Dereference
5003 and then not Is_Constrained (Atyp)
5005 Activate_Range_Check (N);
5009 Indx := First_Index (Atyp);
5010 Subs := First (Expressions (P));
5013 Ttyp := Etype (Indx);
5022 -- For now, ignore all other cases, they are not so interesting
5025 if Debug_Flag_CC then
5026 w (" target type not found, flag set");
5029 Activate_Range_Check (N);
5033 -- Evaluate and check the expression
5038 Target_Type => Ttyp,
5044 if Debug_Flag_CC then
5045 w ("Called Find_Check");
5046 w ("Target_Typ = ", Int (Ttyp));
5050 w (" Check_Num = ", Chk);
5051 w (" Ent = ", Int (Ent));
5052 Write_Str (" Ofs = ");
5057 -- If check is not of form to optimize, then set flag and we are done
5060 if Debug_Flag_CC then
5061 w (" expression not of optimizable type, flag set");
5064 Activate_Range_Check (N);
5068 -- If check is already performed, then return without setting flag
5071 if Debug_Flag_CC then
5072 w ("Check suppressed!");
5078 -- Here we will make a new entry for the new check
5080 Activate_Range_Check (N);
5081 Num_Saved_Checks := Num_Saved_Checks + 1;
5082 Saved_Checks (Num_Saved_Checks) :=
5087 Target_Type => Ttyp);
5089 if Debug_Flag_CC then
5090 w ("Make new entry, check number = ", Num_Saved_Checks);
5091 w (" Entity = ", Int (Ent));
5092 Write_Str (" Offset = ");
5094 w (" Check_Type = R");
5095 w (" Target_Type = ", Int (Ttyp));
5096 pg (Union_Id (Ttyp));
5099 -- If we get an exception, then something went wrong, probably because of
5100 -- an error in the structure of the tree due to an incorrect program. Or
5101 -- it may be a bug in the optimization circuit. In either case the safest
5102 -- thing is simply to set the check flag unconditionally.
5106 Activate_Range_Check (N);
5108 if Debug_Flag_CC then
5109 w (" exception occurred, range flag set");
5113 end Enable_Range_Check;
5119 procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False) is
5120 Typ : constant Entity_Id := Etype (Expr);
5123 -- Ignore call if we are not doing any validity checking
5125 if not Validity_Checks_On then
5128 -- Ignore call if range or validity checks suppressed on entity or type
5130 elsif Range_Or_Validity_Checks_Suppressed (Expr) then
5133 -- No check required if expression is from the expander, we assume the
5134 -- expander will generate whatever checks are needed. Note that this is
5135 -- not just an optimization, it avoids infinite recursions.
5137 -- Unchecked conversions must be checked, unless they are initialized
5138 -- scalar values, as in a component assignment in an init proc.
5140 -- In addition, we force a check if Force_Validity_Checks is set
5142 elsif not Comes_From_Source (Expr)
5143 and then not Force_Validity_Checks
5144 and then (Nkind (Expr) /= N_Unchecked_Type_Conversion
5145 or else Kill_Range_Check (Expr))
5149 -- No check required if expression is known to have valid value
5151 elsif Expr_Known_Valid (Expr) then
5154 -- Ignore case of enumeration with holes where the flag is set not to
5155 -- worry about holes, since no special validity check is needed
5157 elsif Is_Enumeration_Type (Typ)
5158 and then Has_Non_Standard_Rep (Typ)
5163 -- No check required on the left-hand side of an assignment
5165 elsif Nkind (Parent (Expr)) = N_Assignment_Statement
5166 and then Expr = Name (Parent (Expr))
5170 -- No check on a universal real constant. The context will eventually
5171 -- convert it to a machine number for some target type, or report an
5174 elsif Nkind (Expr) = N_Real_Literal
5175 and then Etype (Expr) = Universal_Real
5179 -- If the expression denotes a component of a packed boolean array,
5180 -- no possible check applies. We ignore the old ACATS chestnuts that
5181 -- involve Boolean range True..True.
5183 -- Note: validity checks are generated for expressions that yield a
5184 -- scalar type, when it is possible to create a value that is outside of
5185 -- the type. If this is a one-bit boolean no such value exists. This is
5186 -- an optimization, and it also prevents compiler blowing up during the
5187 -- elaboration of improperly expanded packed array references.
5189 elsif Nkind (Expr) = N_Indexed_Component
5190 and then Is_Bit_Packed_Array (Etype (Prefix (Expr)))
5191 and then Root_Type (Etype (Expr)) = Standard_Boolean
5195 -- For an expression with actions, we want to insert the validity check
5196 -- on the final Expression.
5198 elsif Nkind (Expr) = N_Expression_With_Actions then
5199 Ensure_Valid (Expression (Expr));
5202 -- An annoying special case. If this is an out parameter of a scalar
5203 -- type, then the value is not going to be accessed, therefore it is
5204 -- inappropriate to do any validity check at the call site.
5207 -- Only need to worry about scalar types
5209 if Is_Scalar_Type (Typ) then
5219 -- Find actual argument (which may be a parameter association)
5220 -- and the parent of the actual argument (the call statement)
5225 if Nkind (P) = N_Parameter_Association then
5230 -- Only need to worry if we are argument of a procedure call
5231 -- since functions don't have out parameters. If this is an
5232 -- indirect or dispatching call, get signature from the
5235 if Nkind (P) = N_Procedure_Call_Statement then
5236 L := Parameter_Associations (P);
5238 if Is_Entity_Name (Name (P)) then
5239 E := Entity (Name (P));
5241 pragma Assert (Nkind (Name (P)) = N_Explicit_Dereference);
5242 E := Etype (Name (P));
5245 -- Only need to worry if there are indeed actuals, and if
5246 -- this could be a procedure call, otherwise we cannot get a
5247 -- match (either we are not an argument, or the mode of the
5248 -- formal is not OUT). This test also filters out the
5251 if Is_Non_Empty_List (L) and then Is_Subprogram (E) then
5253 -- This is the loop through parameters, looking for an
5254 -- OUT parameter for which we are the argument.
5256 F := First_Formal (E);
5258 while Present (F) loop
5259 if Ekind (F) = E_Out_Parameter and then A = N then
5272 -- If this is a boolean expression, only its elementary operands need
5273 -- checking: if they are valid, a boolean or short-circuit operation
5274 -- with them will be valid as well.
5276 if Base_Type (Typ) = Standard_Boolean
5278 (Nkind (Expr) in N_Op or else Nkind (Expr) in N_Short_Circuit)
5283 -- If we fall through, a validity check is required
5285 Insert_Valid_Check (Expr);
5287 if Is_Entity_Name (Expr)
5288 and then Safe_To_Capture_Value (Expr, Entity (Expr))
5290 Set_Is_Known_Valid (Entity (Expr));
5294 ----------------------
5295 -- Expr_Known_Valid --
5296 ----------------------
5298 function Expr_Known_Valid (Expr : Node_Id) return Boolean is
5299 Typ : constant Entity_Id := Etype (Expr);
5302 -- Non-scalar types are always considered valid, since they never give
5303 -- rise to the issues of erroneous or bounded error behavior that are
5304 -- the concern. In formal reference manual terms the notion of validity
5305 -- only applies to scalar types. Note that even when packed arrays are
5306 -- represented using modular types, they are still arrays semantically,
5307 -- so they are also always valid (in particular, the unused bits can be
5308 -- random rubbish without affecting the validity of the array value).
5310 if not Is_Scalar_Type (Typ) or else Is_Packed_Array_Type (Typ) then
5313 -- If no validity checking, then everything is considered valid
5315 elsif not Validity_Checks_On then
5318 -- Floating-point types are considered valid unless floating-point
5319 -- validity checks have been specifically turned on.
5321 elsif Is_Floating_Point_Type (Typ)
5322 and then not Validity_Check_Floating_Point
5326 -- If the expression is the value of an object that is known to be
5327 -- valid, then clearly the expression value itself is valid.
5329 elsif Is_Entity_Name (Expr)
5330 and then Is_Known_Valid (Entity (Expr))
5332 -- Exclude volatile variables
5334 and then not Treat_As_Volatile (Entity (Expr))
5338 -- References to discriminants are always considered valid. The value
5339 -- of a discriminant gets checked when the object is built. Within the
5340 -- record, we consider it valid, and it is important to do so, since
5341 -- otherwise we can try to generate bogus validity checks which
5342 -- reference discriminants out of scope. Discriminants of concurrent
5343 -- types are excluded for the same reason.
5345 elsif Is_Entity_Name (Expr)
5346 and then Denotes_Discriminant (Expr, Check_Concurrent => True)
5350 -- If the type is one for which all values are known valid, then we are
5351 -- sure that the value is valid except in the slightly odd case where
5352 -- the expression is a reference to a variable whose size has been
5353 -- explicitly set to a value greater than the object size.
5355 elsif Is_Known_Valid (Typ) then
5356 if Is_Entity_Name (Expr)
5357 and then Ekind (Entity (Expr)) = E_Variable
5358 and then Esize (Entity (Expr)) > Esize (Typ)
5365 -- Integer and character literals always have valid values, where
5366 -- appropriate these will be range checked in any case.
5368 elsif Nkind_In (Expr, N_Integer_Literal, N_Character_Literal) then
5371 -- Real literals are assumed to be valid in VM targets
5373 elsif VM_Target /= No_VM and then Nkind (Expr) = N_Real_Literal then
5376 -- If we have a type conversion or a qualification of a known valid
5377 -- value, then the result will always be valid.
5379 elsif Nkind_In (Expr, N_Type_Conversion, N_Qualified_Expression) then
5380 return Expr_Known_Valid (Expression (Expr));
5382 -- Case of expression is a non-floating-point operator. In this case we
5383 -- can assume the result is valid the generated code for the operator
5384 -- will include whatever checks are needed (e.g. range checks) to ensure
5385 -- validity. This assumption does not hold for the floating-point case,
5386 -- since floating-point operators can generate Infinite or NaN results
5387 -- which are considered invalid.
5389 -- Historical note: in older versions, the exemption of floating-point
5390 -- types from this assumption was done only in cases where the parent
5391 -- was an assignment, function call or parameter association. Presumably
5392 -- the idea was that in other contexts, the result would be checked
5393 -- elsewhere, but this list of cases was missing tests (at least the
5394 -- N_Object_Declaration case, as shown by a reported missing validity
5395 -- check), and it is not clear why function calls but not procedure
5396 -- calls were tested for. It really seems more accurate and much
5397 -- safer to recognize that expressions which are the result of a
5398 -- floating-point operator can never be assumed to be valid.
5400 elsif Nkind (Expr) in N_Op and then not Is_Floating_Point_Type (Typ) then
5403 -- The result of a membership test is always valid, since it is true or
5404 -- false, there are no other possibilities.
5406 elsif Nkind (Expr) in N_Membership_Test then
5409 -- For all other cases, we do not know the expression is valid
5414 end Expr_Known_Valid;
5420 procedure Find_Check
5422 Check_Type : Character;
5423 Target_Type : Entity_Id;
5424 Entry_OK : out Boolean;
5425 Check_Num : out Nat;
5426 Ent : out Entity_Id;
5429 function Within_Range_Of
5430 (Target_Type : Entity_Id;
5431 Check_Type : Entity_Id) return Boolean;
5432 -- Given a requirement for checking a range against Target_Type, and
5433 -- and a range Check_Type against which a check has already been made,
5434 -- determines if the check against check type is sufficient to ensure
5435 -- that no check against Target_Type is required.
5437 ---------------------
5438 -- Within_Range_Of --
5439 ---------------------
5441 function Within_Range_Of
5442 (Target_Type : Entity_Id;
5443 Check_Type : Entity_Id) return Boolean
5446 if Target_Type = Check_Type then
5451 Tlo : constant Node_Id := Type_Low_Bound (Target_Type);
5452 Thi : constant Node_Id := Type_High_Bound (Target_Type);
5453 Clo : constant Node_Id := Type_Low_Bound (Check_Type);
5454 Chi : constant Node_Id := Type_High_Bound (Check_Type);
5458 or else (Compile_Time_Known_Value (Tlo)
5460 Compile_Time_Known_Value (Clo)
5462 Expr_Value (Clo) >= Expr_Value (Tlo)))
5465 or else (Compile_Time_Known_Value (Thi)
5467 Compile_Time_Known_Value (Chi)
5469 Expr_Value (Chi) <= Expr_Value (Clo)))
5477 end Within_Range_Of;
5479 -- Start of processing for Find_Check
5482 -- Establish default, in case no entry is found
5486 -- Case of expression is simple entity reference
5488 if Is_Entity_Name (Expr) then
5489 Ent := Entity (Expr);
5492 -- Case of expression is entity + known constant
5494 elsif Nkind (Expr) = N_Op_Add
5495 and then Compile_Time_Known_Value (Right_Opnd (Expr))
5496 and then Is_Entity_Name (Left_Opnd (Expr))
5498 Ent := Entity (Left_Opnd (Expr));
5499 Ofs := Expr_Value (Right_Opnd (Expr));
5501 -- Case of expression is entity - known constant
5503 elsif Nkind (Expr) = N_Op_Subtract
5504 and then Compile_Time_Known_Value (Right_Opnd (Expr))
5505 and then Is_Entity_Name (Left_Opnd (Expr))
5507 Ent := Entity (Left_Opnd (Expr));
5508 Ofs := UI_Negate (Expr_Value (Right_Opnd (Expr)));
5510 -- Any other expression is not of the right form
5519 -- Come here with expression of appropriate form, check if entity is an
5520 -- appropriate one for our purposes.
5522 if (Ekind (Ent) = E_Variable
5523 or else Is_Constant_Object (Ent))
5524 and then not Is_Library_Level_Entity (Ent)
5532 -- See if there is matching check already
5534 for J in reverse 1 .. Num_Saved_Checks loop
5536 SC : Saved_Check renames Saved_Checks (J);
5538 if SC.Killed = False
5539 and then SC.Entity = Ent
5540 and then SC.Offset = Ofs
5541 and then SC.Check_Type = Check_Type
5542 and then Within_Range_Of (Target_Type, SC.Target_Type)
5550 -- If we fall through entry was not found
5555 ---------------------------------
5556 -- Generate_Discriminant_Check --
5557 ---------------------------------
5559 -- Note: the code for this procedure is derived from the
5560 -- Emit_Discriminant_Check Routine in trans.c.
5562 procedure Generate_Discriminant_Check (N : Node_Id) is
5563 Loc : constant Source_Ptr := Sloc (N);
5564 Pref : constant Node_Id := Prefix (N);
5565 Sel : constant Node_Id := Selector_Name (N);
5567 Orig_Comp : constant Entity_Id :=
5568 Original_Record_Component (Entity (Sel));
5569 -- The original component to be checked
5571 Discr_Fct : constant Entity_Id :=
5572 Discriminant_Checking_Func (Orig_Comp);
5573 -- The discriminant checking function
5576 -- One discriminant to be checked in the type
5578 Real_Discr : Entity_Id;
5579 -- Actual discriminant in the call
5581 Pref_Type : Entity_Id;
5582 -- Type of relevant prefix (ignoring private/access stuff)
5585 -- List of arguments for function call
5588 -- Keep track of the formal corresponding to the actual we build for
5589 -- each discriminant, in order to be able to perform the necessary type
5593 -- Selected component reference for checking function argument
5596 Pref_Type := Etype (Pref);
5598 -- Force evaluation of the prefix, so that it does not get evaluated
5599 -- twice (once for the check, once for the actual reference). Such a
5600 -- double evaluation is always a potential source of inefficiency, and
5601 -- is functionally incorrect in the volatile case, or when the prefix
5602 -- may have side-effects. A non-volatile entity or a component of a
5603 -- non-volatile entity requires no evaluation.
5605 if Is_Entity_Name (Pref) then
5606 if Treat_As_Volatile (Entity (Pref)) then
5607 Force_Evaluation (Pref, Name_Req => True);
5610 elsif Treat_As_Volatile (Etype (Pref)) then
5611 Force_Evaluation (Pref, Name_Req => True);
5613 elsif Nkind (Pref) = N_Selected_Component
5614 and then Is_Entity_Name (Prefix (Pref))
5619 Force_Evaluation (Pref, Name_Req => True);
5622 -- For a tagged type, use the scope of the original component to
5623 -- obtain the type, because ???
5625 if Is_Tagged_Type (Scope (Orig_Comp)) then
5626 Pref_Type := Scope (Orig_Comp);
5628 -- For an untagged derived type, use the discriminants of the parent
5629 -- which have been renamed in the derivation, possibly by a one-to-many
5630 -- discriminant constraint. For non-tagged type, initially get the Etype
5634 if Is_Derived_Type (Pref_Type)
5635 and then Number_Discriminants (Pref_Type) /=
5636 Number_Discriminants (Etype (Base_Type (Pref_Type)))
5638 Pref_Type := Etype (Base_Type (Pref_Type));
5642 -- We definitely should have a checking function, This routine should
5643 -- not be called if no discriminant checking function is present.
5645 pragma Assert (Present (Discr_Fct));
5647 -- Create the list of the actual parameters for the call. This list
5648 -- is the list of the discriminant fields of the record expression to
5649 -- be discriminant checked.
5652 Formal := First_Formal (Discr_Fct);
5653 Discr := First_Discriminant (Pref_Type);
5654 while Present (Discr) loop
5656 -- If we have a corresponding discriminant field, and a parent
5657 -- subtype is present, then we want to use the corresponding
5658 -- discriminant since this is the one with the useful value.
5660 if Present (Corresponding_Discriminant (Discr))
5661 and then Ekind (Pref_Type) = E_Record_Type
5662 and then Present (Parent_Subtype (Pref_Type))
5664 Real_Discr := Corresponding_Discriminant (Discr);
5666 Real_Discr := Discr;
5669 -- Construct the reference to the discriminant
5672 Make_Selected_Component (Loc,
5674 Unchecked_Convert_To (Pref_Type,
5675 Duplicate_Subexpr (Pref)),
5676 Selector_Name => New_Occurrence_Of (Real_Discr, Loc));
5678 -- Manually analyze and resolve this selected component. We really
5679 -- want it just as it appears above, and do not want the expander
5680 -- playing discriminal games etc with this reference. Then we append
5681 -- the argument to the list we are gathering.
5683 Set_Etype (Scomp, Etype (Real_Discr));
5684 Set_Analyzed (Scomp, True);
5685 Append_To (Args, Convert_To (Etype (Formal), Scomp));
5687 Next_Formal_With_Extras (Formal);
5688 Next_Discriminant (Discr);
5691 -- Now build and insert the call
5694 Make_Raise_Constraint_Error (Loc,
5696 Make_Function_Call (Loc,
5697 Name => New_Occurrence_Of (Discr_Fct, Loc),
5698 Parameter_Associations => Args),
5699 Reason => CE_Discriminant_Check_Failed));
5700 end Generate_Discriminant_Check;
5702 ---------------------------
5703 -- Generate_Index_Checks --
5704 ---------------------------
5706 procedure Generate_Index_Checks (N : Node_Id) is
5708 function Entity_Of_Prefix return Entity_Id;
5709 -- Returns the entity of the prefix of N (or Empty if not found)
5711 ----------------------
5712 -- Entity_Of_Prefix --
5713 ----------------------
5715 function Entity_Of_Prefix return Entity_Id is
5720 while not Is_Entity_Name (P) loop
5721 if not Nkind_In (P, N_Selected_Component,
5722 N_Indexed_Component)
5731 end Entity_Of_Prefix;
5735 Loc : constant Source_Ptr := Sloc (N);
5736 A : constant Node_Id := Prefix (N);
5737 A_Ent : constant Entity_Id := Entity_Of_Prefix;
5740 -- Start of processing for Generate_Index_Checks
5743 -- Ignore call if the prefix is not an array since we have a serious
5744 -- error in the sources. Ignore it also if index checks are suppressed
5745 -- for array object or type.
5747 if not Is_Array_Type (Etype (A))
5748 or else (Present (A_Ent) and then Index_Checks_Suppressed (A_Ent))
5749 or else Index_Checks_Suppressed (Etype (A))
5753 -- The indexed component we are dealing with contains 'Loop_Entry in its
5754 -- prefix. This case arises when analysis has determined that constructs
5757 -- Prefix'Loop_Entry (Expr)
5758 -- Prefix'Loop_Entry (Expr1, Expr2, ... ExprN)
5760 -- require rewriting for error detection purposes. A side effect of this
5761 -- action is the generation of index checks that mention 'Loop_Entry.
5762 -- Delay the generation of the check until 'Loop_Entry has been properly
5763 -- expanded. This is done in Expand_Loop_Entry_Attributes.
5765 elsif Nkind (Prefix (N)) = N_Attribute_Reference
5766 and then Attribute_Name (Prefix (N)) = Name_Loop_Entry
5771 -- Generate a raise of constraint error with the appropriate reason and
5772 -- a condition of the form:
5774 -- Base_Type (Sub) not in Array'Range (Subscript)
5776 -- Note that the reason we generate the conversion to the base type here
5777 -- is that we definitely want the range check to take place, even if it
5778 -- looks like the subtype is OK. Optimization considerations that allow
5779 -- us to omit the check have already been taken into account in the
5780 -- setting of the Do_Range_Check flag earlier on.
5782 Sub := First (Expressions (N));
5784 -- Handle string literals
5786 if Ekind (Etype (A)) = E_String_Literal_Subtype then
5787 if Do_Range_Check (Sub) then
5788 Set_Do_Range_Check (Sub, False);
5790 -- For string literals we obtain the bounds of the string from the
5791 -- associated subtype.
5794 Make_Raise_Constraint_Error (Loc,
5798 Convert_To (Base_Type (Etype (Sub)),
5799 Duplicate_Subexpr_Move_Checks (Sub)),
5801 Make_Attribute_Reference (Loc,
5802 Prefix => New_Occurrence_Of (Etype (A), Loc),
5803 Attribute_Name => Name_Range)),
5804 Reason => CE_Index_Check_Failed));
5811 A_Idx : Node_Id := Empty;
5818 A_Idx := First_Index (Etype (A));
5820 while Present (Sub) loop
5821 if Do_Range_Check (Sub) then
5822 Set_Do_Range_Check (Sub, False);
5824 -- Force evaluation except for the case of a simple name of
5825 -- a non-volatile entity.
5827 if not Is_Entity_Name (Sub)
5828 or else Treat_As_Volatile (Entity (Sub))
5830 Force_Evaluation (Sub);
5833 if Nkind (A_Idx) = N_Range then
5836 elsif Nkind (A_Idx) = N_Identifier
5837 or else Nkind (A_Idx) = N_Expanded_Name
5839 A_Range := Scalar_Range (Entity (A_Idx));
5841 else pragma Assert (Nkind (A_Idx) = N_Subtype_Indication);
5842 A_Range := Range_Expression (Constraint (A_Idx));
5845 -- For array objects with constant bounds we can generate
5846 -- the index check using the bounds of the type of the index
5849 and then Ekind (A_Ent) = E_Variable
5850 and then Is_Constant_Bound (Low_Bound (A_Range))
5851 and then Is_Constant_Bound (High_Bound (A_Range))
5854 Make_Attribute_Reference (Loc,
5856 New_Occurrence_Of (Etype (A_Idx), Loc),
5857 Attribute_Name => Name_Range);
5859 -- For arrays with non-constant bounds we cannot generate
5860 -- the index check using the bounds of the type of the index
5861 -- since it may reference discriminants of some enclosing
5862 -- type. We obtain the bounds directly from the prefix
5869 Num := New_List (Make_Integer_Literal (Loc, Ind));
5873 Make_Attribute_Reference (Loc,
5875 Duplicate_Subexpr_Move_Checks (A, Name_Req => True),
5876 Attribute_Name => Name_Range,
5877 Expressions => Num);
5881 Make_Raise_Constraint_Error (Loc,
5885 Convert_To (Base_Type (Etype (Sub)),
5886 Duplicate_Subexpr_Move_Checks (Sub)),
5887 Right_Opnd => Range_N),
5888 Reason => CE_Index_Check_Failed));
5891 A_Idx := Next_Index (A_Idx);
5897 end Generate_Index_Checks;
5899 --------------------------
5900 -- Generate_Range_Check --
5901 --------------------------
5903 procedure Generate_Range_Check
5905 Target_Type : Entity_Id;
5906 Reason : RT_Exception_Code)
5908 Loc : constant Source_Ptr := Sloc (N);
5909 Source_Type : constant Entity_Id := Etype (N);
5910 Source_Base_Type : constant Entity_Id := Base_Type (Source_Type);
5911 Target_Base_Type : constant Entity_Id := Base_Type (Target_Type);
5914 -- First special case, if the source type is already within the range
5915 -- of the target type, then no check is needed (probably we should have
5916 -- stopped Do_Range_Check from being set in the first place, but better
5917 -- late than never in preventing junk code.
5919 if In_Subrange_Of (Source_Type, Target_Type)
5921 -- We do NOT apply this if the source node is a literal, since in this
5922 -- case the literal has already been labeled as having the subtype of
5926 (Nkind_In (N, N_Integer_Literal, N_Real_Literal, N_Character_Literal)
5929 and then Ekind (Entity (N)) = E_Enumeration_Literal))
5931 -- Also do not apply this for floating-point if Check_Float_Overflow
5934 (Is_Floating_Point_Type (Source_Type) and Check_Float_Overflow)
5939 -- We need a check, so force evaluation of the node, so that it does
5940 -- not get evaluated twice (once for the check, once for the actual
5941 -- reference). Such a double evaluation is always a potential source
5942 -- of inefficiency, and is functionally incorrect in the volatile case.
5944 if not Is_Entity_Name (N) or else Treat_As_Volatile (Entity (N)) then
5945 Force_Evaluation (N);
5948 -- The easiest case is when Source_Base_Type and Target_Base_Type are
5949 -- the same since in this case we can simply do a direct check of the
5950 -- value of N against the bounds of Target_Type.
5952 -- [constraint_error when N not in Target_Type]
5954 -- Note: this is by far the most common case, for example all cases of
5955 -- checks on the RHS of assignments are in this category, but not all
5956 -- cases are like this. Notably conversions can involve two types.
5958 if Source_Base_Type = Target_Base_Type then
5960 Make_Raise_Constraint_Error (Loc,
5963 Left_Opnd => Duplicate_Subexpr (N),
5964 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
5967 -- Next test for the case where the target type is within the bounds
5968 -- of the base type of the source type, since in this case we can
5969 -- simply convert these bounds to the base type of T to do the test.
5971 -- [constraint_error when N not in
5972 -- Source_Base_Type (Target_Type'First)
5974 -- Source_Base_Type(Target_Type'Last))]
5976 -- The conversions will always work and need no check
5978 -- Unchecked_Convert_To is used instead of Convert_To to handle the case
5979 -- of converting from an enumeration value to an integer type, such as
5980 -- occurs for the case of generating a range check on Enum'Val(Exp)
5981 -- (which used to be handled by gigi). This is OK, since the conversion
5982 -- itself does not require a check.
5984 elsif In_Subrange_Of (Target_Type, Source_Base_Type) then
5986 Make_Raise_Constraint_Error (Loc,
5989 Left_Opnd => Duplicate_Subexpr (N),
5994 Unchecked_Convert_To (Source_Base_Type,
5995 Make_Attribute_Reference (Loc,
5997 New_Occurrence_Of (Target_Type, Loc),
5998 Attribute_Name => Name_First)),
6001 Unchecked_Convert_To (Source_Base_Type,
6002 Make_Attribute_Reference (Loc,
6004 New_Occurrence_Of (Target_Type, Loc),
6005 Attribute_Name => Name_Last)))),
6008 -- Note that at this stage we now that the Target_Base_Type is not in
6009 -- the range of the Source_Base_Type (since even the Target_Type itself
6010 -- is not in this range). It could still be the case that Source_Type is
6011 -- in range of the target base type since we have not checked that case.
6013 -- If that is the case, we can freely convert the source to the target,
6014 -- and then test the target result against the bounds.
6016 elsif In_Subrange_Of (Source_Type, Target_Base_Type) then
6018 -- We make a temporary to hold the value of the converted value
6019 -- (converted to the base type), and then we will do the test against
6022 -- Tnn : constant Target_Base_Type := Target_Base_Type (N);
6023 -- [constraint_error when Tnn not in Target_Type]
6025 -- Then the conversion itself is replaced by an occurrence of Tnn
6028 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
6031 Insert_Actions (N, New_List (
6032 Make_Object_Declaration (Loc,
6033 Defining_Identifier => Tnn,
6034 Object_Definition =>
6035 New_Occurrence_Of (Target_Base_Type, Loc),
6036 Constant_Present => True,
6038 Make_Type_Conversion (Loc,
6039 Subtype_Mark => New_Occurrence_Of (Target_Base_Type, Loc),
6040 Expression => Duplicate_Subexpr (N))),
6042 Make_Raise_Constraint_Error (Loc,
6045 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
6046 Right_Opnd => New_Occurrence_Of (Target_Type, Loc)),
6048 Reason => Reason)));
6050 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
6052 -- Set the type of N, because the declaration for Tnn might not
6053 -- be analyzed yet, as is the case if N appears within a record
6054 -- declaration, as a discriminant constraint or expression.
6056 Set_Etype (N, Target_Base_Type);
6059 -- At this stage, we know that we have two scalar types, which are
6060 -- directly convertible, and where neither scalar type has a base
6061 -- range that is in the range of the other scalar type.
6063 -- The only way this can happen is with a signed and unsigned type.
6064 -- So test for these two cases:
6067 -- Case of the source is unsigned and the target is signed
6069 if Is_Unsigned_Type (Source_Base_Type)
6070 and then not Is_Unsigned_Type (Target_Base_Type)
6072 -- If the source is unsigned and the target is signed, then we
6073 -- know that the source is not shorter than the target (otherwise
6074 -- the source base type would be in the target base type range).
6076 -- In other words, the unsigned type is either the same size as
6077 -- the target, or it is larger. It cannot be smaller.
6080 (Esize (Source_Base_Type) >= Esize (Target_Base_Type));
6082 -- We only need to check the low bound if the low bound of the
6083 -- target type is non-negative. If the low bound of the target
6084 -- type is negative, then we know that we will fit fine.
6086 -- If the high bound of the target type is negative, then we
6087 -- know we have a constraint error, since we can't possibly
6088 -- have a negative source.
6090 -- With these two checks out of the way, we can do the check
6091 -- using the source type safely
6093 -- This is definitely the most annoying case.
6095 -- [constraint_error
6096 -- when (Target_Type'First >= 0
6098 -- N < Source_Base_Type (Target_Type'First))
6099 -- or else Target_Type'Last < 0
6100 -- or else N > Source_Base_Type (Target_Type'Last)];
6102 -- We turn off all checks since we know that the conversions
6103 -- will work fine, given the guards for negative values.
6106 Make_Raise_Constraint_Error (Loc,
6112 Left_Opnd => Make_Op_Ge (Loc,
6114 Make_Attribute_Reference (Loc,
6116 New_Occurrence_Of (Target_Type, Loc),
6117 Attribute_Name => Name_First),
6118 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
6122 Left_Opnd => Duplicate_Subexpr (N),
6124 Convert_To (Source_Base_Type,
6125 Make_Attribute_Reference (Loc,
6127 New_Occurrence_Of (Target_Type, Loc),
6128 Attribute_Name => Name_First)))),
6133 Make_Attribute_Reference (Loc,
6134 Prefix => New_Occurrence_Of (Target_Type, Loc),
6135 Attribute_Name => Name_Last),
6136 Right_Opnd => Make_Integer_Literal (Loc, Uint_0))),
6140 Left_Opnd => Duplicate_Subexpr (N),
6142 Convert_To (Source_Base_Type,
6143 Make_Attribute_Reference (Loc,
6144 Prefix => New_Occurrence_Of (Target_Type, Loc),
6145 Attribute_Name => Name_Last)))),
6148 Suppress => All_Checks);
6150 -- Only remaining possibility is that the source is signed and
6151 -- the target is unsigned.
6154 pragma Assert (not Is_Unsigned_Type (Source_Base_Type)
6155 and then Is_Unsigned_Type (Target_Base_Type));
6157 -- If the source is signed and the target is unsigned, then we
6158 -- know that the target is not shorter than the source (otherwise
6159 -- the target base type would be in the source base type range).
6161 -- In other words, the unsigned type is either the same size as
6162 -- the target, or it is larger. It cannot be smaller.
6164 -- Clearly we have an error if the source value is negative since
6165 -- no unsigned type can have negative values. If the source type
6166 -- is non-negative, then the check can be done using the target
6169 -- Tnn : constant Target_Base_Type (N) := Target_Type;
6171 -- [constraint_error
6172 -- when N < 0 or else Tnn not in Target_Type];
6174 -- We turn off all checks for the conversion of N to the target
6175 -- base type, since we generate the explicit check to ensure that
6176 -- the value is non-negative
6179 Tnn : constant Entity_Id := Make_Temporary (Loc, 'T', N);
6182 Insert_Actions (N, New_List (
6183 Make_Object_Declaration (Loc,
6184 Defining_Identifier => Tnn,
6185 Object_Definition =>
6186 New_Occurrence_Of (Target_Base_Type, Loc),
6187 Constant_Present => True,
6189 Make_Unchecked_Type_Conversion (Loc,
6191 New_Occurrence_Of (Target_Base_Type, Loc),
6192 Expression => Duplicate_Subexpr (N))),
6194 Make_Raise_Constraint_Error (Loc,
6199 Left_Opnd => Duplicate_Subexpr (N),
6200 Right_Opnd => Make_Integer_Literal (Loc, Uint_0)),
6204 Left_Opnd => New_Occurrence_Of (Tnn, Loc),
6206 New_Occurrence_Of (Target_Type, Loc))),
6209 Suppress => All_Checks);
6211 -- Set the Etype explicitly, because Insert_Actions may have
6212 -- placed the declaration in the freeze list for an enclosing
6213 -- construct, and thus it is not analyzed yet.
6215 Set_Etype (Tnn, Target_Base_Type);
6216 Rewrite (N, New_Occurrence_Of (Tnn, Loc));
6220 end Generate_Range_Check;
6226 function Get_Check_Id (N : Name_Id) return Check_Id is
6228 -- For standard check name, we can do a direct computation
6230 if N in First_Check_Name .. Last_Check_Name then
6231 return Check_Id (N - (First_Check_Name - 1));
6233 -- For non-standard names added by pragma Check_Name, search table
6236 for J in All_Checks + 1 .. Check_Names.Last loop
6237 if Check_Names.Table (J) = N then
6243 -- No matching name found
6248 ---------------------
6249 -- Get_Discriminal --
6250 ---------------------
6252 function Get_Discriminal (E : Entity_Id; Bound : Node_Id) return Node_Id is
6253 Loc : constant Source_Ptr := Sloc (E);
6258 -- The bound can be a bona fide parameter of a protected operation,
6259 -- rather than a prival encoded as an in-parameter.
6261 if No (Discriminal_Link (Entity (Bound))) then
6265 -- Climb the scope stack looking for an enclosing protected type. If
6266 -- we run out of scopes, return the bound itself.
6269 while Present (Sc) loop
6270 if Sc = Standard_Standard then
6272 elsif Ekind (Sc) = E_Protected_Type then
6279 D := First_Discriminant (Sc);
6280 while Present (D) loop
6281 if Chars (D) = Chars (Bound) then
6282 return New_Occurrence_Of (Discriminal (D), Loc);
6285 Next_Discriminant (D);
6289 end Get_Discriminal;
6291 ----------------------
6292 -- Get_Range_Checks --
6293 ----------------------
6295 function Get_Range_Checks
6297 Target_Typ : Entity_Id;
6298 Source_Typ : Entity_Id := Empty;
6299 Warn_Node : Node_Id := Empty) return Check_Result
6303 Selected_Range_Checks (Ck_Node, Target_Typ, Source_Typ, Warn_Node);
6304 end Get_Range_Checks;
6310 function Guard_Access
6313 Ck_Node : Node_Id) return Node_Id
6316 if Nkind (Cond) = N_Or_Else then
6317 Set_Paren_Count (Cond, 1);
6320 if Nkind (Ck_Node) = N_Allocator then
6328 Left_Opnd => Duplicate_Subexpr_No_Checks (Ck_Node),
6329 Right_Opnd => Make_Null (Loc)),
6330 Right_Opnd => Cond);
6334 -----------------------------
6335 -- Index_Checks_Suppressed --
6336 -----------------------------
6338 function Index_Checks_Suppressed (E : Entity_Id) return Boolean is
6340 if Present (E) and then Checks_May_Be_Suppressed (E) then
6341 return Is_Check_Suppressed (E, Index_Check);
6343 return Scope_Suppress.Suppress (Index_Check);
6345 end Index_Checks_Suppressed;
6351 procedure Initialize is
6353 for J in Determine_Range_Cache_N'Range loop
6354 Determine_Range_Cache_N (J) := Empty;
6359 for J in Int range 1 .. All_Checks loop
6360 Check_Names.Append (Name_Id (Int (First_Check_Name) + J - 1));
6364 -------------------------
6365 -- Insert_Range_Checks --
6366 -------------------------
6368 procedure Insert_Range_Checks
6369 (Checks : Check_Result;
6371 Suppress_Typ : Entity_Id;
6372 Static_Sloc : Source_Ptr := No_Location;
6373 Flag_Node : Node_Id := Empty;
6374 Do_Before : Boolean := False)
6376 Internal_Flag_Node : Node_Id := Flag_Node;
6377 Internal_Static_Sloc : Source_Ptr := Static_Sloc;
6379 Check_Node : Node_Id;
6380 Checks_On : constant Boolean :=
6381 (not Index_Checks_Suppressed (Suppress_Typ))
6382 or else (not Range_Checks_Suppressed (Suppress_Typ));
6385 -- For now we just return if Checks_On is false, however this should be
6386 -- enhanced to check for an always True value in the condition and to
6387 -- generate a compilation warning???
6389 if not Expander_Active or not Checks_On then
6393 if Static_Sloc = No_Location then
6394 Internal_Static_Sloc := Sloc (Node);
6397 if No (Flag_Node) then
6398 Internal_Flag_Node := Node;
6401 for J in 1 .. 2 loop
6402 exit when No (Checks (J));
6404 if Nkind (Checks (J)) = N_Raise_Constraint_Error
6405 and then Present (Condition (Checks (J)))
6407 if not Has_Dynamic_Range_Check (Internal_Flag_Node) then
6408 Check_Node := Checks (J);
6409 Mark_Rewrite_Insertion (Check_Node);
6412 Insert_Before_And_Analyze (Node, Check_Node);
6414 Insert_After_And_Analyze (Node, Check_Node);
6417 Set_Has_Dynamic_Range_Check (Internal_Flag_Node);
6422 Make_Raise_Constraint_Error (Internal_Static_Sloc,
6423 Reason => CE_Range_Check_Failed);
6424 Mark_Rewrite_Insertion (Check_Node);
6427 Insert_Before_And_Analyze (Node, Check_Node);
6429 Insert_After_And_Analyze (Node, Check_Node);
6433 end Insert_Range_Checks;
6435 ------------------------
6436 -- Insert_Valid_Check --
6437 ------------------------
6439 procedure Insert_Valid_Check (Expr : Node_Id) is
6440 Loc : constant Source_Ptr := Sloc (Expr);
6441 Typ : constant Entity_Id := Etype (Expr);
6445 -- Do not insert if checks off, or if not checking validity or
6446 -- if expression is known to be valid
6448 if not Validity_Checks_On
6449 or else Range_Or_Validity_Checks_Suppressed (Expr)
6450 or else Expr_Known_Valid (Expr)
6455 -- Do not insert checks within a predicate function. This will arise
6456 -- if the current unit and the predicate function are being compiled
6457 -- with validity checks enabled.
6459 if Present (Predicate_Function (Typ))
6460 and then Current_Scope = Predicate_Function (Typ)
6465 -- If the expression is a packed component of a modular type of the
6466 -- right size, the data is always valid.
6468 if Nkind (Expr) = N_Selected_Component
6469 and then Present (Component_Clause (Entity (Selector_Name (Expr))))
6470 and then Is_Modular_Integer_Type (Typ)
6471 and then Modulus (Typ) = 2 ** Esize (Entity (Selector_Name (Expr)))
6476 -- If we have a checked conversion, then validity check applies to
6477 -- the expression inside the conversion, not the result, since if
6478 -- the expression inside is valid, then so is the conversion result.
6481 while Nkind (Exp) = N_Type_Conversion loop
6482 Exp := Expression (Exp);
6485 -- We are about to insert the validity check for Exp. We save and
6486 -- reset the Do_Range_Check flag over this validity check, and then
6487 -- put it back for the final original reference (Exp may be rewritten).
6490 DRC : constant Boolean := Do_Range_Check (Exp);
6495 Set_Do_Range_Check (Exp, False);
6497 -- Force evaluation to avoid multiple reads for atomic/volatile
6499 -- Note: we set Name_Req to False. We used to set it to True, with
6500 -- the thinking that a name is required as the prefix of the 'Valid
6501 -- call, but in fact the check that the prefix of an attribute is
6502 -- a name is in the parser, and we just don't require it here.
6503 -- Moreover, when we set Name_Req to True, that interfered with the
6504 -- checking for Volatile, since we couldn't just capture the value.
6506 if Is_Entity_Name (Exp)
6507 and then Is_Volatile (Entity (Exp))
6509 -- Same reasoning as above for setting Name_Req to False
6511 Force_Evaluation (Exp, Name_Req => False);
6514 -- Build the prefix for the 'Valid call
6516 PV := Duplicate_Subexpr_No_Checks (Exp, Name_Req => False);
6518 -- A rather specialized kludge. If PV is an analyzed expression
6519 -- which is an indexed component of a packed array that has not
6520 -- been properly expanded, turn off its Analyzed flag to make sure
6521 -- it gets properly reexpanded.
6523 -- The reason this arises is that Duplicate_Subexpr_No_Checks did
6524 -- an analyze with the old parent pointer. This may point e.g. to
6525 -- a subprogram call, which deactivates this expansion.
6528 and then Nkind (PV) = N_Indexed_Component
6529 and then Present (Packed_Array_Type (Etype (Prefix (PV))))
6531 Set_Analyzed (PV, False);
6534 -- Build the raise CE node to check for validity. We build a type
6535 -- qualification for the prefix, since it may not be of the form of
6536 -- a name, and we don't care in this context!
6539 Make_Raise_Constraint_Error (Loc,
6543 Make_Attribute_Reference (Loc,
6545 Attribute_Name => Name_Valid)),
6546 Reason => CE_Invalid_Data);
6548 -- Insert the validity check. Note that we do this with validity
6549 -- checks turned off, to avoid recursion, we do not want validity
6550 -- checks on the validity checking code itself.
6552 Insert_Action (Expr, CE, Suppress => Validity_Check);
6554 -- If the expression is a reference to an element of a bit-packed
6555 -- array, then it is rewritten as a renaming declaration. If the
6556 -- expression is an actual in a call, it has not been expanded,
6557 -- waiting for the proper point at which to do it. The same happens
6558 -- with renamings, so that we have to force the expansion now. This
6559 -- non-local complication is due to code in exp_ch2,adb, exp_ch4.adb
6562 if Is_Entity_Name (Exp)
6563 and then Nkind (Parent (Entity (Exp))) =
6564 N_Object_Renaming_Declaration
6567 Old_Exp : constant Node_Id := Name (Parent (Entity (Exp)));
6569 if Nkind (Old_Exp) = N_Indexed_Component
6570 and then Is_Bit_Packed_Array (Etype (Prefix (Old_Exp)))
6572 Expand_Packed_Element_Reference (Old_Exp);
6577 -- Put back the Do_Range_Check flag on the resulting (possibly
6578 -- rewritten) expression.
6580 -- Note: it might be thought that a validity check is not required
6581 -- when a range check is present, but that's not the case, because
6582 -- the back end is allowed to assume for the range check that the
6583 -- operand is within its declared range (an assumption that validity
6584 -- checking is all about NOT assuming).
6586 -- Note: no need to worry about Possible_Local_Raise here, it will
6587 -- already have been called if original node has Do_Range_Check set.
6589 Set_Do_Range_Check (Exp, DRC);
6591 end Insert_Valid_Check;
6593 -------------------------------------
6594 -- Is_Signed_Integer_Arithmetic_Op --
6595 -------------------------------------
6597 function Is_Signed_Integer_Arithmetic_Op (N : Node_Id) return Boolean is
6600 when N_Op_Abs | N_Op_Add | N_Op_Divide | N_Op_Expon |
6601 N_Op_Minus | N_Op_Mod | N_Op_Multiply | N_Op_Plus |
6602 N_Op_Rem | N_Op_Subtract =>
6603 return Is_Signed_Integer_Type (Etype (N));
6605 when N_If_Expression | N_Case_Expression =>
6606 return Is_Signed_Integer_Type (Etype (N));
6611 end Is_Signed_Integer_Arithmetic_Op;
6613 ----------------------------------
6614 -- Install_Null_Excluding_Check --
6615 ----------------------------------
6617 procedure Install_Null_Excluding_Check (N : Node_Id) is
6618 Loc : constant Source_Ptr := Sloc (Parent (N));
6619 Typ : constant Entity_Id := Etype (N);
6621 function Safe_To_Capture_In_Parameter_Value return Boolean;
6622 -- Determines if it is safe to capture Known_Non_Null status for an
6623 -- the entity referenced by node N. The caller ensures that N is indeed
6624 -- an entity name. It is safe to capture the non-null status for an IN
6625 -- parameter when the reference occurs within a declaration that is sure
6626 -- to be executed as part of the declarative region.
6628 procedure Mark_Non_Null;
6629 -- After installation of check, if the node in question is an entity
6630 -- name, then mark this entity as non-null if possible.
6632 function Safe_To_Capture_In_Parameter_Value return Boolean is
6633 E : constant Entity_Id := Entity (N);
6634 S : constant Entity_Id := Current_Scope;
6638 if Ekind (E) /= E_In_Parameter then
6642 -- Two initial context checks. We must be inside a subprogram body
6643 -- with declarations and reference must not appear in nested scopes.
6645 if (Ekind (S) /= E_Function and then Ekind (S) /= E_Procedure)
6646 or else Scope (E) /= S
6651 S_Par := Parent (Parent (S));
6653 if Nkind (S_Par) /= N_Subprogram_Body
6654 or else No (Declarations (S_Par))
6664 -- Retrieve the declaration node of N (if any). Note that N
6665 -- may be a part of a complex initialization expression.
6669 while Present (P) loop
6671 -- If we have a short circuit form, and we are within the right
6672 -- hand expression, we return false, since the right hand side
6673 -- is not guaranteed to be elaborated.
6675 if Nkind (P) in N_Short_Circuit
6676 and then N = Right_Opnd (P)
6681 -- Similarly, if we are in an if expression and not part of the
6682 -- condition, then we return False, since neither the THEN or
6683 -- ELSE dependent expressions will always be elaborated.
6685 if Nkind (P) = N_If_Expression
6686 and then N /= First (Expressions (P))
6691 -- If within a case expression, and not part of the expression,
6692 -- then return False, since a particular dependent expression
6693 -- may not always be elaborated
6695 if Nkind (P) = N_Case_Expression
6696 and then N /= Expression (P)
6701 -- While traversing the parent chain, if node N belongs to a
6702 -- statement, then it may never appear in a declarative region.
6704 if Nkind (P) in N_Statement_Other_Than_Procedure_Call
6705 or else Nkind (P) = N_Procedure_Call_Statement
6710 -- If we are at a declaration, record it and exit
6712 if Nkind (P) in N_Declaration
6713 and then Nkind (P) not in N_Subprogram_Specification
6726 return List_Containing (N_Decl) = Declarations (S_Par);
6728 end Safe_To_Capture_In_Parameter_Value;
6734 procedure Mark_Non_Null is
6736 -- Only case of interest is if node N is an entity name
6738 if Is_Entity_Name (N) then
6740 -- For sure, we want to clear an indication that this is known to
6741 -- be null, since if we get past this check, it definitely is not.
6743 Set_Is_Known_Null (Entity (N), False);
6745 -- We can mark the entity as known to be non-null if either it is
6746 -- safe to capture the value, or in the case of an IN parameter,
6747 -- which is a constant, if the check we just installed is in the
6748 -- declarative region of the subprogram body. In this latter case,
6749 -- a check is decisive for the rest of the body if the expression
6750 -- is sure to be elaborated, since we know we have to elaborate
6751 -- all declarations before executing the body.
6753 -- Couldn't this always be part of Safe_To_Capture_Value ???
6755 if Safe_To_Capture_Value (N, Entity (N))
6756 or else Safe_To_Capture_In_Parameter_Value
6758 Set_Is_Known_Non_Null (Entity (N));
6763 -- Start of processing for Install_Null_Excluding_Check
6766 pragma Assert (Is_Access_Type (Typ));
6768 -- No check inside a generic, check will be emitted in instance
6770 if Inside_A_Generic then
6774 -- No check needed if known to be non-null
6776 if Known_Non_Null (N) then
6780 -- If known to be null, here is where we generate a compile time check
6782 if Known_Null (N) then
6784 -- Avoid generating warning message inside init procs. In SPARK mode
6785 -- we can go ahead and call Apply_Compile_Time_Constraint_Error
6786 -- since it will be turned into an error in any case.
6788 if (not Inside_Init_Proc or else SPARK_Mode = On)
6790 -- Do not emit the warning within a conditional expression,
6791 -- where the expression might not be evaluated, and the warning
6792 -- appear as extraneous noise.
6794 and then not Within_Case_Or_If_Expression (N)
6796 Apply_Compile_Time_Constraint_Error
6797 (N, "null value not allowed here??", CE_Access_Check_Failed);
6799 -- Remaining cases, where we silently insert the raise
6803 Make_Raise_Constraint_Error (Loc,
6804 Reason => CE_Access_Check_Failed));
6811 -- If entity is never assigned, for sure a warning is appropriate
6813 if Is_Entity_Name (N) then
6814 Check_Unset_Reference (N);
6817 -- No check needed if checks are suppressed on the range. Note that we
6818 -- don't set Is_Known_Non_Null in this case (we could legitimately do
6819 -- so, since the program is erroneous, but we don't like to casually
6820 -- propagate such conclusions from erroneosity).
6822 if Access_Checks_Suppressed (Typ) then
6826 -- No check needed for access to concurrent record types generated by
6827 -- the expander. This is not just an optimization (though it does indeed
6828 -- remove junk checks). It also avoids generation of junk warnings.
6830 if Nkind (N) in N_Has_Chars
6831 and then Chars (N) = Name_uObject
6832 and then Is_Concurrent_Record_Type
6833 (Directly_Designated_Type (Etype (N)))
6838 -- No check needed in interface thunks since the runtime check is
6839 -- already performed at the caller side.
6841 if Is_Thunk (Current_Scope) then
6845 -- No check needed for the Get_Current_Excep.all.all idiom generated by
6846 -- the expander within exception handlers, since we know that the value
6847 -- can never be null.
6849 -- Is this really the right way to do this? Normally we generate such
6850 -- code in the expander with checks off, and that's how we suppress this
6851 -- kind of junk check ???
6853 if Nkind (N) = N_Function_Call
6854 and then Nkind (Name (N)) = N_Explicit_Dereference
6855 and then Nkind (Prefix (Name (N))) = N_Identifier
6856 and then Is_RTE (Entity (Prefix (Name (N))), RE_Get_Current_Excep)
6861 -- Otherwise install access check
6864 Make_Raise_Constraint_Error (Loc,
6867 Left_Opnd => Duplicate_Subexpr_Move_Checks (N),
6868 Right_Opnd => Make_Null (Loc)),
6869 Reason => CE_Access_Check_Failed));
6872 end Install_Null_Excluding_Check;
6874 --------------------------
6875 -- Install_Static_Check --
6876 --------------------------
6878 procedure Install_Static_Check (R_Cno : Node_Id; Loc : Source_Ptr) is
6879 Stat : constant Boolean := Is_Static_Expression (R_Cno);
6880 Typ : constant Entity_Id := Etype (R_Cno);
6884 Make_Raise_Constraint_Error (Loc,
6885 Reason => CE_Range_Check_Failed));
6886 Set_Analyzed (R_Cno);
6887 Set_Etype (R_Cno, Typ);
6888 Set_Raises_Constraint_Error (R_Cno);
6889 Set_Is_Static_Expression (R_Cno, Stat);
6891 -- Now deal with possible local raise handling
6893 Possible_Local_Raise (R_Cno, Standard_Constraint_Error);
6894 end Install_Static_Check;
6896 -------------------------
6897 -- Is_Check_Suppressed --
6898 -------------------------
6900 function Is_Check_Suppressed (E : Entity_Id; C : Check_Id) return Boolean is
6901 Ptr : Suppress_Stack_Entry_Ptr;
6904 -- First search the local entity suppress stack. We search this from the
6905 -- top of the stack down so that we get the innermost entry that applies
6906 -- to this case if there are nested entries.
6908 Ptr := Local_Suppress_Stack_Top;
6909 while Ptr /= null loop
6910 if (Ptr.Entity = Empty or else Ptr.Entity = E)
6911 and then (Ptr.Check = All_Checks or else Ptr.Check = C)
6913 return Ptr.Suppress;
6919 -- Now search the global entity suppress table for a matching entry.
6920 -- We also search this from the top down so that if there are multiple
6921 -- pragmas for the same entity, the last one applies (not clear what
6922 -- or whether the RM specifies this handling, but it seems reasonable).
6924 Ptr := Global_Suppress_Stack_Top;
6925 while Ptr /= null loop
6926 if (Ptr.Entity = Empty or else Ptr.Entity = E)
6927 and then (Ptr.Check = All_Checks or else Ptr.Check = C)
6929 return Ptr.Suppress;
6935 -- If we did not find a matching entry, then use the normal scope
6936 -- suppress value after all (actually this will be the global setting
6937 -- since it clearly was not overridden at any point). For a predefined
6938 -- check, we test the specific flag. For a user defined check, we check
6939 -- the All_Checks flag. The Overflow flag requires special handling to
6940 -- deal with the General vs Assertion case
6942 if C = Overflow_Check then
6943 return Overflow_Checks_Suppressed (Empty);
6944 elsif C in Predefined_Check_Id then
6945 return Scope_Suppress.Suppress (C);
6947 return Scope_Suppress.Suppress (All_Checks);
6949 end Is_Check_Suppressed;
6951 ---------------------
6952 -- Kill_All_Checks --
6953 ---------------------
6955 procedure Kill_All_Checks is
6957 if Debug_Flag_CC then
6958 w ("Kill_All_Checks");
6961 -- We reset the number of saved checks to zero, and also modify all
6962 -- stack entries for statement ranges to indicate that the number of
6963 -- checks at each level is now zero.
6965 Num_Saved_Checks := 0;
6967 -- Note: the Int'Min here avoids any possibility of J being out of
6968 -- range when called from e.g. Conditional_Statements_Begin.
6970 for J in 1 .. Int'Min (Saved_Checks_TOS, Saved_Checks_Stack'Last) loop
6971 Saved_Checks_Stack (J) := 0;
6973 end Kill_All_Checks;
6979 procedure Kill_Checks (V : Entity_Id) is
6981 if Debug_Flag_CC then
6982 w ("Kill_Checks for entity", Int (V));
6985 for J in 1 .. Num_Saved_Checks loop
6986 if Saved_Checks (J).Entity = V then
6987 if Debug_Flag_CC then
6988 w (" Checks killed for saved check ", J);
6991 Saved_Checks (J).Killed := True;
6996 ------------------------------
6997 -- Length_Checks_Suppressed --
6998 ------------------------------
7000 function Length_Checks_Suppressed (E : Entity_Id) return Boolean is
7002 if Present (E) and then Checks_May_Be_Suppressed (E) then
7003 return Is_Check_Suppressed (E, Length_Check);
7005 return Scope_Suppress.Suppress (Length_Check);
7007 end Length_Checks_Suppressed;
7009 -----------------------
7010 -- Make_Bignum_Block --
7011 -----------------------
7013 function Make_Bignum_Block (Loc : Source_Ptr) return Node_Id is
7014 M : constant Entity_Id := Make_Defining_Identifier (Loc, Name_uM);
7018 Make_Block_Statement (Loc,
7019 Declarations => New_List (
7020 Make_Object_Declaration (Loc,
7021 Defining_Identifier => M,
7022 Object_Definition =>
7023 New_Occurrence_Of (RTE (RE_Mark_Id), Loc),
7025 Make_Function_Call (Loc,
7026 Name => New_Occurrence_Of (RTE (RE_SS_Mark), Loc)))),
7028 Handled_Statement_Sequence =>
7029 Make_Handled_Sequence_Of_Statements (Loc,
7030 Statements => New_List (
7031 Make_Procedure_Call_Statement (Loc,
7032 Name => New_Occurrence_Of (RTE (RE_SS_Release), Loc),
7033 Parameter_Associations => New_List (
7034 New_Occurrence_Of (M, Loc))))));
7035 end Make_Bignum_Block;
7037 ----------------------------------
7038 -- Minimize_Eliminate_Overflows --
7039 ----------------------------------
7041 -- This is a recursive routine that is called at the top of an expression
7042 -- tree to properly process overflow checking for a whole subtree by making
7043 -- recursive calls to process operands. This processing may involve the use
7044 -- of bignum or long long integer arithmetic, which will change the types
7045 -- of operands and results. That's why we can't do this bottom up (since
7046 -- it would interfere with semantic analysis).
7048 -- What happens is that if MINIMIZED/ELIMINATED mode is in effect then
7049 -- the operator expansion routines, as well as the expansion routines for
7050 -- if/case expression, do nothing (for the moment) except call the routine
7051 -- to apply the overflow check (Apply_Arithmetic_Overflow_Check). That
7052 -- routine does nothing for non top-level nodes, so at the point where the
7053 -- call is made for the top level node, the entire expression subtree has
7054 -- not been expanded, or processed for overflow. All that has to happen as
7055 -- a result of the top level call to this routine.
7057 -- As noted above, the overflow processing works by making recursive calls
7058 -- for the operands, and figuring out what to do, based on the processing
7059 -- of these operands (e.g. if a bignum operand appears, the parent op has
7060 -- to be done in bignum mode), and the determined ranges of the operands.
7062 -- After possible rewriting of a constituent subexpression node, a call is
7063 -- made to either reexpand the node (if nothing has changed) or reanalyze
7064 -- the node (if it has been modified by the overflow check processing). The
7065 -- Analyzed_Flag is set to False before the reexpand/reanalyze. To avoid
7066 -- a recursive call into the whole overflow apparatus, an important rule
7067 -- for this call is that the overflow handling mode must be temporarily set
7070 procedure Minimize_Eliminate_Overflows
7074 Top_Level : Boolean)
7076 Rtyp : constant Entity_Id := Etype (N);
7077 pragma Assert (Is_Signed_Integer_Type (Rtyp));
7078 -- Result type, must be a signed integer type
7080 Check_Mode : constant Overflow_Mode_Type := Overflow_Check_Mode;
7081 pragma Assert (Check_Mode in Minimized_Or_Eliminated);
7083 Loc : constant Source_Ptr := Sloc (N);
7086 -- Ranges of values for right operand (operator case)
7089 -- Ranges of values for left operand (operator case)
7091 LLIB : constant Entity_Id := Base_Type (Standard_Long_Long_Integer);
7092 -- Operands and results are of this type when we convert
7094 LLLo : constant Uint := Intval (Type_Low_Bound (LLIB));
7095 LLHi : constant Uint := Intval (Type_High_Bound (LLIB));
7096 -- Bounds of Long_Long_Integer
7098 Binary : constant Boolean := Nkind (N) in N_Binary_Op;
7099 -- Indicates binary operator case
7102 -- Used in call to Determine_Range
7104 Bignum_Operands : Boolean;
7105 -- Set True if one or more operands is already of type Bignum, meaning
7106 -- that for sure (regardless of Top_Level setting) we are committed to
7107 -- doing the operation in Bignum mode (or in the case of a case or if
7108 -- expression, converting all the dependent expressions to Bignum).
7110 Long_Long_Integer_Operands : Boolean;
7111 -- Set True if one or more operands is already of type Long_Long_Integer
7112 -- which means that if the result is known to be in the result type
7113 -- range, then we must convert such operands back to the result type.
7115 procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False);
7116 -- This is called when we have modified the node and we therefore need
7117 -- to reanalyze it. It is important that we reset the mode to STRICT for
7118 -- this reanalysis, since if we leave it in MINIMIZED or ELIMINATED mode
7119 -- we would reenter this routine recursively which would not be good.
7120 -- The argument Suppress is set True if we also want to suppress
7121 -- overflow checking for the reexpansion (this is set when we know
7122 -- overflow is not possible). Typ is the type for the reanalysis.
7124 procedure Reexpand (Suppress : Boolean := False);
7125 -- This is like Reanalyze, but does not do the Analyze step, it only
7126 -- does a reexpansion. We do this reexpansion in STRICT mode, so that
7127 -- instead of reentering the MINIMIZED/ELIMINATED mode processing, we
7128 -- follow the normal expansion path (e.g. converting A**4 to A**2**2).
7129 -- Note that skipping reanalysis is not just an optimization, testing
7130 -- has showed up several complex cases in which reanalyzing an already
7131 -- analyzed node causes incorrect behavior.
7133 function In_Result_Range return Boolean;
7134 -- Returns True iff Lo .. Hi are within range of the result type
7136 procedure Max (A : in out Uint; B : Uint);
7137 -- If A is No_Uint, sets A to B, else to UI_Max (A, B)
7139 procedure Min (A : in out Uint; B : Uint);
7140 -- If A is No_Uint, sets A to B, else to UI_Min (A, B)
7142 ---------------------
7143 -- In_Result_Range --
7144 ---------------------
7146 function In_Result_Range return Boolean is
7148 if Lo = No_Uint or else Hi = No_Uint then
7151 elsif Is_Static_Subtype (Etype (N)) then
7152 return Lo >= Expr_Value (Type_Low_Bound (Rtyp))
7154 Hi <= Expr_Value (Type_High_Bound (Rtyp));
7157 return Lo >= Expr_Value (Type_Low_Bound (Base_Type (Rtyp)))
7159 Hi <= Expr_Value (Type_High_Bound (Base_Type (Rtyp)));
7161 end In_Result_Range;
7167 procedure Max (A : in out Uint; B : Uint) is
7169 if A = No_Uint or else B > A then
7178 procedure Min (A : in out Uint; B : Uint) is
7180 if A = No_Uint or else B < A then
7189 procedure Reanalyze (Typ : Entity_Id; Suppress : Boolean := False) is
7190 Svg : constant Overflow_Mode_Type :=
7191 Scope_Suppress.Overflow_Mode_General;
7192 Sva : constant Overflow_Mode_Type :=
7193 Scope_Suppress.Overflow_Mode_Assertions;
7194 Svo : constant Boolean :=
7195 Scope_Suppress.Suppress (Overflow_Check);
7198 Scope_Suppress.Overflow_Mode_General := Strict;
7199 Scope_Suppress.Overflow_Mode_Assertions := Strict;
7202 Scope_Suppress.Suppress (Overflow_Check) := True;
7205 Analyze_And_Resolve (N, Typ);
7207 Scope_Suppress.Suppress (Overflow_Check) := Svo;
7208 Scope_Suppress.Overflow_Mode_General := Svg;
7209 Scope_Suppress.Overflow_Mode_Assertions := Sva;
7216 procedure Reexpand (Suppress : Boolean := False) is
7217 Svg : constant Overflow_Mode_Type :=
7218 Scope_Suppress.Overflow_Mode_General;
7219 Sva : constant Overflow_Mode_Type :=
7220 Scope_Suppress.Overflow_Mode_Assertions;
7221 Svo : constant Boolean :=
7222 Scope_Suppress.Suppress (Overflow_Check);
7225 Scope_Suppress.Overflow_Mode_General := Strict;
7226 Scope_Suppress.Overflow_Mode_Assertions := Strict;
7227 Set_Analyzed (N, False);
7230 Scope_Suppress.Suppress (Overflow_Check) := True;
7235 Scope_Suppress.Suppress (Overflow_Check) := Svo;
7236 Scope_Suppress.Overflow_Mode_General := Svg;
7237 Scope_Suppress.Overflow_Mode_Assertions := Sva;
7240 -- Start of processing for Minimize_Eliminate_Overflows
7243 -- Case where we do not have a signed integer arithmetic operation
7245 if not Is_Signed_Integer_Arithmetic_Op (N) then
7247 -- Use the normal Determine_Range routine to get the range. We
7248 -- don't require operands to be valid, invalid values may result in
7249 -- rubbish results where the result has not been properly checked for
7250 -- overflow, that's fine.
7252 Determine_Range (N, OK, Lo, Hi, Assume_Valid => False);
7254 -- If Determine_Range did not work (can this in fact happen? Not
7255 -- clear but might as well protect), use type bounds.
7258 Lo := Intval (Type_Low_Bound (Base_Type (Etype (N))));
7259 Hi := Intval (Type_High_Bound (Base_Type (Etype (N))));
7262 -- If we don't have a binary operator, all we have to do is to set
7263 -- the Hi/Lo range, so we are done.
7267 -- Processing for if expression
7269 elsif Nkind (N) = N_If_Expression then
7271 Then_DE : constant Node_Id := Next (First (Expressions (N)));
7272 Else_DE : constant Node_Id := Next (Then_DE);
7275 Bignum_Operands := False;
7277 Minimize_Eliminate_Overflows
7278 (Then_DE, Lo, Hi, Top_Level => False);
7280 if Lo = No_Uint then
7281 Bignum_Operands := True;
7284 Minimize_Eliminate_Overflows
7285 (Else_DE, Rlo, Rhi, Top_Level => False);
7287 if Rlo = No_Uint then
7288 Bignum_Operands := True;
7290 Long_Long_Integer_Operands :=
7291 Etype (Then_DE) = LLIB or else Etype (Else_DE) = LLIB;
7297 -- If at least one of our operands is now Bignum, we must rebuild
7298 -- the if expression to use Bignum operands. We will analyze the
7299 -- rebuilt if expression with overflow checks off, since once we
7300 -- are in bignum mode, we are all done with overflow checks.
7302 if Bignum_Operands then
7304 Make_If_Expression (Loc,
7305 Expressions => New_List (
7306 Remove_Head (Expressions (N)),
7307 Convert_To_Bignum (Then_DE),
7308 Convert_To_Bignum (Else_DE)),
7309 Is_Elsif => Is_Elsif (N)));
7311 Reanalyze (RTE (RE_Bignum), Suppress => True);
7313 -- If we have no Long_Long_Integer operands, then we are in result
7314 -- range, since it means that none of our operands felt the need
7315 -- to worry about overflow (otherwise it would have already been
7316 -- converted to long long integer or bignum). We reexpand to
7317 -- complete the expansion of the if expression (but we do not
7318 -- need to reanalyze).
7320 elsif not Long_Long_Integer_Operands then
7321 Set_Do_Overflow_Check (N, False);
7324 -- Otherwise convert us to long long integer mode. Note that we
7325 -- don't need any further overflow checking at this level.
7328 Convert_To_And_Rewrite (LLIB, Then_DE);
7329 Convert_To_And_Rewrite (LLIB, Else_DE);
7330 Set_Etype (N, LLIB);
7332 -- Now reanalyze with overflow checks off
7334 Set_Do_Overflow_Check (N, False);
7335 Reanalyze (LLIB, Suppress => True);
7341 -- Here for case expression
7343 elsif Nkind (N) = N_Case_Expression then
7344 Bignum_Operands := False;
7345 Long_Long_Integer_Operands := False;
7351 -- Loop through expressions applying recursive call
7353 Alt := First (Alternatives (N));
7354 while Present (Alt) loop
7356 Aexp : constant Node_Id := Expression (Alt);
7359 Minimize_Eliminate_Overflows
7360 (Aexp, Lo, Hi, Top_Level => False);
7362 if Lo = No_Uint then
7363 Bignum_Operands := True;
7364 elsif Etype (Aexp) = LLIB then
7365 Long_Long_Integer_Operands := True;
7372 -- If we have no bignum or long long integer operands, it means
7373 -- that none of our dependent expressions could raise overflow.
7374 -- In this case, we simply return with no changes except for
7375 -- resetting the overflow flag, since we are done with overflow
7376 -- checks for this node. We will reexpand to get the needed
7377 -- expansion for the case expression, but we do not need to
7378 -- reanalyze, since nothing has changed.
7380 if not (Bignum_Operands or Long_Long_Integer_Operands) then
7381 Set_Do_Overflow_Check (N, False);
7382 Reexpand (Suppress => True);
7384 -- Otherwise we are going to rebuild the case expression using
7385 -- either bignum or long long integer operands throughout.
7394 New_Alts := New_List;
7395 Alt := First (Alternatives (N));
7396 while Present (Alt) loop
7397 if Bignum_Operands then
7398 New_Exp := Convert_To_Bignum (Expression (Alt));
7399 Rtype := RTE (RE_Bignum);
7401 New_Exp := Convert_To (LLIB, Expression (Alt));
7405 Append_To (New_Alts,
7406 Make_Case_Expression_Alternative (Sloc (Alt),
7408 Discrete_Choices => Discrete_Choices (Alt),
7409 Expression => New_Exp));
7415 Make_Case_Expression (Loc,
7416 Expression => Expression (N),
7417 Alternatives => New_Alts));
7419 Reanalyze (Rtype, Suppress => True);
7427 -- If we have an arithmetic operator we make recursive calls on the
7428 -- operands to get the ranges (and to properly process the subtree
7429 -- that lies below us).
7431 Minimize_Eliminate_Overflows
7432 (Right_Opnd (N), Rlo, Rhi, Top_Level => False);
7435 Minimize_Eliminate_Overflows
7436 (Left_Opnd (N), Llo, Lhi, Top_Level => False);
7439 -- Record if we have Long_Long_Integer operands
7441 Long_Long_Integer_Operands :=
7442 Etype (Right_Opnd (N)) = LLIB
7443 or else (Binary and then Etype (Left_Opnd (N)) = LLIB);
7445 -- If either operand is a bignum, then result will be a bignum and we
7446 -- don't need to do any range analysis. As previously discussed we could
7447 -- do range analysis in such cases, but it could mean working with giant
7448 -- numbers at compile time for very little gain (the number of cases
7449 -- in which we could slip back from bignum mode is small).
7451 if Rlo = No_Uint or else (Binary and then Llo = No_Uint) then
7454 Bignum_Operands := True;
7456 -- Otherwise compute result range
7459 Bignum_Operands := False;
7467 Hi := UI_Max (abs Rlo, abs Rhi);
7479 -- If the right operand can only be zero, set 0..0
7481 if Rlo = 0 and then Rhi = 0 then
7485 -- Possible bounds of division must come from dividing end
7486 -- values of the input ranges (four possibilities), provided
7487 -- zero is not included in the possible values of the right
7490 -- Otherwise, we just consider two intervals of values for
7491 -- the right operand: the interval of negative values (up to
7492 -- -1) and the interval of positive values (starting at 1).
7493 -- Since division by 1 is the identity, and division by -1
7494 -- is negation, we get all possible bounds of division in that
7495 -- case by considering:
7496 -- - all values from the division of end values of input
7498 -- - the end values of the left operand;
7499 -- - the negation of the end values of the left operand.
7503 Mrk : constant Uintp.Save_Mark := Mark;
7504 -- Mark so we can release the RR and Ev values
7512 -- Discard extreme values of zero for the divisor, since
7513 -- they will simply result in an exception in any case.
7521 -- Compute possible bounds coming from dividing end
7522 -- values of the input ranges.
7529 Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4));
7530 Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4));
7532 -- If the right operand can be both negative or positive,
7533 -- include the end values of the left operand in the
7534 -- extreme values, as well as their negation.
7536 if Rlo < 0 and then Rhi > 0 then
7543 UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4)));
7545 UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4)));
7548 -- Release the RR and Ev values
7550 Release_And_Save (Mrk, Lo, Hi);
7558 -- Discard negative values for the exponent, since they will
7559 -- simply result in an exception in any case.
7567 -- Estimate number of bits in result before we go computing
7568 -- giant useless bounds. Basically the number of bits in the
7569 -- result is the number of bits in the base multiplied by the
7570 -- value of the exponent. If this is big enough that the result
7571 -- definitely won't fit in Long_Long_Integer, switch to bignum
7572 -- mode immediately, and avoid computing giant bounds.
7574 -- The comparison here is approximate, but conservative, it
7575 -- only clicks on cases that are sure to exceed the bounds.
7577 if Num_Bits (UI_Max (abs Llo, abs Lhi)) * Rhi + 1 > 100 then
7581 -- If right operand is zero then result is 1
7588 -- High bound comes either from exponentiation of largest
7589 -- positive value to largest exponent value, or from
7590 -- the exponentiation of most negative value to an
7604 if Rhi mod 2 = 0 then
7607 Hi2 := Llo ** (Rhi - 1);
7613 Hi := UI_Max (Hi1, Hi2);
7616 -- Result can only be negative if base can be negative
7619 if Rhi mod 2 = 0 then
7620 Lo := Llo ** (Rhi - 1);
7625 -- Otherwise low bound is minimum ** minimum
7642 Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1;
7643 -- This is the maximum absolute value of the result
7649 -- The result depends only on the sign and magnitude of
7650 -- the right operand, it does not depend on the sign or
7651 -- magnitude of the left operand.
7664 when N_Op_Multiply =>
7666 -- Possible bounds of multiplication must come from multiplying
7667 -- end values of the input ranges (four possibilities).
7670 Mrk : constant Uintp.Save_Mark := Mark;
7671 -- Mark so we can release the Ev values
7673 Ev1 : constant Uint := Llo * Rlo;
7674 Ev2 : constant Uint := Llo * Rhi;
7675 Ev3 : constant Uint := Lhi * Rlo;
7676 Ev4 : constant Uint := Lhi * Rhi;
7679 Lo := UI_Min (UI_Min (Ev1, Ev2), UI_Min (Ev3, Ev4));
7680 Hi := UI_Max (UI_Max (Ev1, Ev2), UI_Max (Ev3, Ev4));
7682 -- Release the Ev values
7684 Release_And_Save (Mrk, Lo, Hi);
7687 -- Plus operator (affirmation)
7697 Maxabs : constant Uint := UI_Max (abs Rlo, abs Rhi) - 1;
7698 -- This is the maximum absolute value of the result. Note
7699 -- that the result range does not depend on the sign of the
7706 -- Case of left operand negative, which results in a range
7707 -- of -Maxabs .. 0 for those negative values. If there are
7708 -- no negative values then Lo value of result is always 0.
7714 -- Case of left operand positive
7723 when N_Op_Subtract =>
7727 -- Nothing else should be possible
7730 raise Program_Error;
7734 -- Here for the case where we have not rewritten anything (no bignum
7735 -- operands or long long integer operands), and we know the result.
7736 -- If we know we are in the result range, and we do not have Bignum
7737 -- operands or Long_Long_Integer operands, we can just reexpand with
7738 -- overflow checks turned off (since we know we cannot have overflow).
7739 -- As always the reexpansion is required to complete expansion of the
7740 -- operator, but we do not need to reanalyze, and we prevent recursion
7741 -- by suppressing the check.
7743 if not (Bignum_Operands or Long_Long_Integer_Operands)
7744 and then In_Result_Range
7746 Set_Do_Overflow_Check (N, False);
7747 Reexpand (Suppress => True);
7750 -- Here we know that we are not in the result range, and in the general
7751 -- case we will move into either the Bignum or Long_Long_Integer domain
7752 -- to compute the result. However, there is one exception. If we are
7753 -- at the top level, and we do not have Bignum or Long_Long_Integer
7754 -- operands, we will have to immediately convert the result back to
7755 -- the result type, so there is no point in Bignum/Long_Long_Integer
7759 and then not (Bignum_Operands or Long_Long_Integer_Operands)
7761 -- One further refinement. If we are at the top level, but our parent
7762 -- is a type conversion, then go into bignum or long long integer node
7763 -- since the result will be converted to that type directly without
7764 -- going through the result type, and we may avoid an overflow. This
7765 -- is the case for example of Long_Long_Integer (A ** 4), where A is
7766 -- of type Integer, and the result A ** 4 fits in Long_Long_Integer
7767 -- but does not fit in Integer.
7769 and then Nkind (Parent (N)) /= N_Type_Conversion
7771 -- Here keep original types, but we need to complete analysis
7773 -- One subtlety. We can't just go ahead and do an analyze operation
7774 -- here because it will cause recursion into the whole MINIMIZED/
7775 -- ELIMINATED overflow processing which is not what we want. Here
7776 -- we are at the top level, and we need a check against the result
7777 -- mode (i.e. we want to use STRICT mode). So do exactly that.
7778 -- Also, we have not modified the node, so this is a case where
7779 -- we need to reexpand, but not reanalyze.
7784 -- Cases where we do the operation in Bignum mode. This happens either
7785 -- because one of our operands is in Bignum mode already, or because
7786 -- the computed bounds are outside the bounds of Long_Long_Integer,
7787 -- which in some cases can be indicated by Hi and Lo being No_Uint.
7789 -- Note: we could do better here and in some cases switch back from
7790 -- Bignum mode to normal mode, e.g. big mod 2 must be in the range
7791 -- 0 .. 1, but the cases are rare and it is not worth the effort.
7792 -- Failing to do this switching back is only an efficiency issue.
7794 elsif Lo = No_Uint or else Lo < LLLo or else Hi > LLHi then
7796 -- OK, we are definitely outside the range of Long_Long_Integer. The
7797 -- question is whether to move to Bignum mode, or stay in the domain
7798 -- of Long_Long_Integer, signalling that an overflow check is needed.
7800 -- Obviously in MINIMIZED mode we stay with LLI, since we are not in
7801 -- the Bignum business. In ELIMINATED mode, we will normally move
7802 -- into Bignum mode, but there is an exception if neither of our
7803 -- operands is Bignum now, and we are at the top level (Top_Level
7804 -- set True). In this case, there is no point in moving into Bignum
7805 -- mode to prevent overflow if the caller will immediately convert
7806 -- the Bignum value back to LLI with an overflow check. It's more
7807 -- efficient to stay in LLI mode with an overflow check (if needed)
7809 if Check_Mode = Minimized
7810 or else (Top_Level and not Bignum_Operands)
7812 if Do_Overflow_Check (N) then
7813 Enable_Overflow_Check (N);
7816 -- The result now has to be in Long_Long_Integer mode, so adjust
7817 -- the possible range to reflect this. Note these calls also
7818 -- change No_Uint values from the top level case to LLI bounds.
7823 -- Otherwise we are in ELIMINATED mode and we switch to Bignum mode
7826 pragma Assert (Check_Mode = Eliminated);
7835 Fent := RTE (RE_Big_Abs);
7838 Fent := RTE (RE_Big_Add);
7841 Fent := RTE (RE_Big_Div);
7844 Fent := RTE (RE_Big_Exp);
7847 Fent := RTE (RE_Big_Neg);
7850 Fent := RTE (RE_Big_Mod);
7852 when N_Op_Multiply =>
7853 Fent := RTE (RE_Big_Mul);
7856 Fent := RTE (RE_Big_Rem);
7858 when N_Op_Subtract =>
7859 Fent := RTE (RE_Big_Sub);
7861 -- Anything else is an internal error, this includes the
7862 -- N_Op_Plus case, since how can plus cause the result
7863 -- to be out of range if the operand is in range?
7866 raise Program_Error;
7869 -- Construct argument list for Bignum call, converting our
7870 -- operands to Bignum form if they are not already there.
7875 Append_To (Args, Convert_To_Bignum (Left_Opnd (N)));
7878 Append_To (Args, Convert_To_Bignum (Right_Opnd (N)));
7880 -- Now rewrite the arithmetic operator with a call to the
7881 -- corresponding bignum function.
7884 Make_Function_Call (Loc,
7885 Name => New_Occurrence_Of (Fent, Loc),
7886 Parameter_Associations => Args));
7887 Reanalyze (RTE (RE_Bignum), Suppress => True);
7889 -- Indicate result is Bignum mode
7897 -- Otherwise we are in range of Long_Long_Integer, so no overflow
7898 -- check is required, at least not yet.
7901 Set_Do_Overflow_Check (N, False);
7904 -- Here we are not in Bignum territory, but we may have long long
7905 -- integer operands that need special handling. First a special check:
7906 -- If an exponentiation operator exponent is of type Long_Long_Integer,
7907 -- it means we converted it to prevent overflow, but exponentiation
7908 -- requires a Natural right operand, so convert it back to Natural.
7909 -- This conversion may raise an exception which is fine.
7911 if Nkind (N) = N_Op_Expon and then Etype (Right_Opnd (N)) = LLIB then
7912 Convert_To_And_Rewrite (Standard_Natural, Right_Opnd (N));
7915 -- Here we will do the operation in Long_Long_Integer. We do this even
7916 -- if we know an overflow check is required, better to do this in long
7917 -- long integer mode, since we are less likely to overflow.
7919 -- Convert right or only operand to Long_Long_Integer, except that
7920 -- we do not touch the exponentiation right operand.
7922 if Nkind (N) /= N_Op_Expon then
7923 Convert_To_And_Rewrite (LLIB, Right_Opnd (N));
7926 -- Convert left operand to Long_Long_Integer for binary case
7929 Convert_To_And_Rewrite (LLIB, Left_Opnd (N));
7932 -- Reset node to unanalyzed
7934 Set_Analyzed (N, False);
7935 Set_Etype (N, Empty);
7936 Set_Entity (N, Empty);
7938 -- Now analyze this new node. This reanalysis will complete processing
7939 -- for the node. In particular we will complete the expansion of an
7940 -- exponentiation operator (e.g. changing A ** 2 to A * A), and also
7941 -- we will complete any division checks (since we have not changed the
7942 -- setting of the Do_Division_Check flag).
7944 -- We do this reanalysis in STRICT mode to avoid recursion into the
7945 -- MINIMIZED/ELIMINATED handling, since we are now done with that.
7948 SG : constant Overflow_Mode_Type :=
7949 Scope_Suppress.Overflow_Mode_General;
7950 SA : constant Overflow_Mode_Type :=
7951 Scope_Suppress.Overflow_Mode_Assertions;
7954 Scope_Suppress.Overflow_Mode_General := Strict;
7955 Scope_Suppress.Overflow_Mode_Assertions := Strict;
7957 if not Do_Overflow_Check (N) then
7958 Reanalyze (LLIB, Suppress => True);
7963 Scope_Suppress.Overflow_Mode_General := SG;
7964 Scope_Suppress.Overflow_Mode_Assertions := SA;
7966 end Minimize_Eliminate_Overflows;
7968 -------------------------
7969 -- Overflow_Check_Mode --
7970 -------------------------
7972 function Overflow_Check_Mode return Overflow_Mode_Type is
7974 if In_Assertion_Expr = 0 then
7975 return Scope_Suppress.Overflow_Mode_General;
7977 return Scope_Suppress.Overflow_Mode_Assertions;
7979 end Overflow_Check_Mode;
7981 --------------------------------
7982 -- Overflow_Checks_Suppressed --
7983 --------------------------------
7985 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean is
7987 if Present (E) and then Checks_May_Be_Suppressed (E) then
7988 return Is_Check_Suppressed (E, Overflow_Check);
7990 return Scope_Suppress.Suppress (Overflow_Check);
7992 end Overflow_Checks_Suppressed;
7994 ---------------------------------
7995 -- Predicate_Checks_Suppressed --
7996 ---------------------------------
7998 function Predicate_Checks_Suppressed (E : Entity_Id) return Boolean is
8000 if Present (E) and then Checks_May_Be_Suppressed (E) then
8001 return Is_Check_Suppressed (E, Predicate_Check);
8003 return Scope_Suppress.Suppress (Predicate_Check);
8005 end Predicate_Checks_Suppressed;
8007 -----------------------------
8008 -- Range_Checks_Suppressed --
8009 -----------------------------
8011 function Range_Checks_Suppressed (E : Entity_Id) return Boolean is
8015 -- Note: for now we always suppress range checks on Vax float types,
8016 -- since Gigi does not know how to generate these checks.
8018 if Vax_Float (E) then
8020 elsif Kill_Range_Checks (E) then
8022 elsif Checks_May_Be_Suppressed (E) then
8023 return Is_Check_Suppressed (E, Range_Check);
8027 return Scope_Suppress.Suppress (Range_Check);
8028 end Range_Checks_Suppressed;
8030 -----------------------------------------
8031 -- Range_Or_Validity_Checks_Suppressed --
8032 -----------------------------------------
8034 -- Note: the coding would be simpler here if we simply made appropriate
8035 -- calls to Range/Validity_Checks_Suppressed, but that would result in
8036 -- duplicated checks which we prefer to avoid.
8038 function Range_Or_Validity_Checks_Suppressed
8039 (Expr : Node_Id) return Boolean
8042 -- Immediate return if scope checks suppressed for either check
8044 if Scope_Suppress.Suppress (Range_Check)
8046 Scope_Suppress.Suppress (Validity_Check)
8051 -- If no expression, that's odd, decide that checks are suppressed,
8052 -- since we don't want anyone trying to do checks in this case, which
8053 -- is most likely the result of some other error.
8059 -- Expression is present, so perform suppress checks on type
8062 Typ : constant Entity_Id := Etype (Expr);
8064 if Vax_Float (Typ) then
8066 elsif Checks_May_Be_Suppressed (Typ)
8067 and then (Is_Check_Suppressed (Typ, Range_Check)
8069 Is_Check_Suppressed (Typ, Validity_Check))
8075 -- If expression is an entity name, perform checks on this entity
8077 if Is_Entity_Name (Expr) then
8079 Ent : constant Entity_Id := Entity (Expr);
8081 if Checks_May_Be_Suppressed (Ent) then
8082 return Is_Check_Suppressed (Ent, Range_Check)
8083 or else Is_Check_Suppressed (Ent, Validity_Check);
8088 -- If we fall through, no checks suppressed
8091 end Range_Or_Validity_Checks_Suppressed;
8097 procedure Remove_Checks (Expr : Node_Id) is
8098 function Process (N : Node_Id) return Traverse_Result;
8099 -- Process a single node during the traversal
8101 procedure Traverse is new Traverse_Proc (Process);
8102 -- The traversal procedure itself
8108 function Process (N : Node_Id) return Traverse_Result is
8110 if Nkind (N) not in N_Subexpr then
8114 Set_Do_Range_Check (N, False);
8118 Traverse (Left_Opnd (N));
8121 when N_Attribute_Reference =>
8122 Set_Do_Overflow_Check (N, False);
8124 when N_Function_Call =>
8125 Set_Do_Tag_Check (N, False);
8128 Set_Do_Overflow_Check (N, False);
8132 Set_Do_Division_Check (N, False);
8135 Set_Do_Length_Check (N, False);
8138 Set_Do_Division_Check (N, False);
8141 Set_Do_Length_Check (N, False);
8144 Set_Do_Division_Check (N, False);
8147 Set_Do_Length_Check (N, False);
8154 Traverse (Left_Opnd (N));
8157 when N_Selected_Component =>
8158 Set_Do_Discriminant_Check (N, False);
8160 when N_Type_Conversion =>
8161 Set_Do_Length_Check (N, False);
8162 Set_Do_Tag_Check (N, False);
8163 Set_Do_Overflow_Check (N, False);
8172 -- Start of processing for Remove_Checks
8178 ----------------------------
8179 -- Selected_Length_Checks --
8180 ----------------------------
8182 function Selected_Length_Checks
8184 Target_Typ : Entity_Id;
8185 Source_Typ : Entity_Id;
8186 Warn_Node : Node_Id) return Check_Result
8188 Loc : constant Source_Ptr := Sloc (Ck_Node);
8191 Expr_Actual : Node_Id;
8193 Cond : Node_Id := Empty;
8194 Do_Access : Boolean := False;
8195 Wnode : Node_Id := Warn_Node;
8196 Ret_Result : Check_Result := (Empty, Empty);
8197 Num_Checks : Natural := 0;
8199 procedure Add_Check (N : Node_Id);
8200 -- Adds the action given to Ret_Result if N is non-Empty
8202 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id;
8203 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id;
8204 -- Comments required ???
8206 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean;
8207 -- True for equal literals and for nodes that denote the same constant
8208 -- entity, even if its value is not a static constant. This includes the
8209 -- case of a discriminal reference within an init proc. Removes some
8210 -- obviously superfluous checks.
8212 function Length_E_Cond
8213 (Exptyp : Entity_Id;
8215 Indx : Nat) return Node_Id;
8216 -- Returns expression to compute:
8217 -- Typ'Length /= Exptyp'Length
8219 function Length_N_Cond
8222 Indx : Nat) return Node_Id;
8223 -- Returns expression to compute:
8224 -- Typ'Length /= Expr'Length
8230 procedure Add_Check (N : Node_Id) is
8234 -- For now, ignore attempt to place more than two checks ???
8235 -- This is really worrisome, are we really discarding checks ???
8237 if Num_Checks = 2 then
8241 pragma Assert (Num_Checks <= 1);
8242 Num_Checks := Num_Checks + 1;
8243 Ret_Result (Num_Checks) := N;
8251 function Get_E_Length (E : Entity_Id; Indx : Nat) return Node_Id is
8252 SE : constant Entity_Id := Scope (E);
8254 E1 : Entity_Id := E;
8257 if Ekind (Scope (E)) = E_Record_Type
8258 and then Has_Discriminants (Scope (E))
8260 N := Build_Discriminal_Subtype_Of_Component (E);
8263 Insert_Action (Ck_Node, N);
8264 E1 := Defining_Identifier (N);
8268 if Ekind (E1) = E_String_Literal_Subtype then
8270 Make_Integer_Literal (Loc,
8271 Intval => String_Literal_Length (E1));
8273 elsif SE /= Standard_Standard
8274 and then Ekind (Scope (SE)) = E_Protected_Type
8275 and then Has_Discriminants (Scope (SE))
8276 and then Has_Completion (Scope (SE))
8277 and then not Inside_Init_Proc
8279 -- If the type whose length is needed is a private component
8280 -- constrained by a discriminant, we must expand the 'Length
8281 -- attribute into an explicit computation, using the discriminal
8282 -- of the current protected operation. This is because the actual
8283 -- type of the prival is constructed after the protected opera-
8284 -- tion has been fully expanded.
8287 Indx_Type : Node_Id;
8290 Do_Expand : Boolean := False;
8293 Indx_Type := First_Index (E);
8295 for J in 1 .. Indx - 1 loop
8296 Next_Index (Indx_Type);
8299 Get_Index_Bounds (Indx_Type, Lo, Hi);
8301 if Nkind (Lo) = N_Identifier
8302 and then Ekind (Entity (Lo)) = E_In_Parameter
8304 Lo := Get_Discriminal (E, Lo);
8308 if Nkind (Hi) = N_Identifier
8309 and then Ekind (Entity (Hi)) = E_In_Parameter
8311 Hi := Get_Discriminal (E, Hi);
8316 if not Is_Entity_Name (Lo) then
8317 Lo := Duplicate_Subexpr_No_Checks (Lo);
8320 if not Is_Entity_Name (Hi) then
8321 Lo := Duplicate_Subexpr_No_Checks (Hi);
8327 Make_Op_Subtract (Loc,
8331 Right_Opnd => Make_Integer_Literal (Loc, 1));
8336 Make_Attribute_Reference (Loc,
8337 Attribute_Name => Name_Length,
8339 New_Occurrence_Of (E1, Loc));
8342 Set_Expressions (N, New_List (
8343 Make_Integer_Literal (Loc, Indx)));
8352 Make_Attribute_Reference (Loc,
8353 Attribute_Name => Name_Length,
8355 New_Occurrence_Of (E1, Loc));
8358 Set_Expressions (N, New_List (
8359 Make_Integer_Literal (Loc, Indx)));
8370 function Get_N_Length (N : Node_Id; Indx : Nat) return Node_Id is
8373 Make_Attribute_Reference (Loc,
8374 Attribute_Name => Name_Length,
8376 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
8377 Expressions => New_List (
8378 Make_Integer_Literal (Loc, Indx)));
8385 function Length_E_Cond
8386 (Exptyp : Entity_Id;
8388 Indx : Nat) return Node_Id
8393 Left_Opnd => Get_E_Length (Typ, Indx),
8394 Right_Opnd => Get_E_Length (Exptyp, Indx));
8401 function Length_N_Cond
8404 Indx : Nat) return Node_Id
8409 Left_Opnd => Get_E_Length (Typ, Indx),
8410 Right_Opnd => Get_N_Length (Expr, Indx));
8417 function Same_Bounds (L : Node_Id; R : Node_Id) return Boolean is
8420 (Nkind (L) = N_Integer_Literal
8421 and then Nkind (R) = N_Integer_Literal
8422 and then Intval (L) = Intval (R))
8426 and then Ekind (Entity (L)) = E_Constant
8427 and then ((Is_Entity_Name (R)
8428 and then Entity (L) = Entity (R))
8430 (Nkind (R) = N_Type_Conversion
8431 and then Is_Entity_Name (Expression (R))
8432 and then Entity (L) = Entity (Expression (R)))))
8436 and then Ekind (Entity (R)) = E_Constant
8437 and then Nkind (L) = N_Type_Conversion
8438 and then Is_Entity_Name (Expression (L))
8439 and then Entity (R) = Entity (Expression (L)))
8443 and then Is_Entity_Name (R)
8444 and then Entity (L) = Entity (R)
8445 and then Ekind (Entity (L)) = E_In_Parameter
8446 and then Inside_Init_Proc);
8449 -- Start of processing for Selected_Length_Checks
8452 if not Expander_Active then
8456 if Target_Typ = Any_Type
8457 or else Target_Typ = Any_Composite
8458 or else Raises_Constraint_Error (Ck_Node)
8467 T_Typ := Target_Typ;
8469 if No (Source_Typ) then
8470 S_Typ := Etype (Ck_Node);
8472 S_Typ := Source_Typ;
8475 if S_Typ = Any_Type or else S_Typ = Any_Composite then
8479 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
8480 S_Typ := Designated_Type (S_Typ);
8481 T_Typ := Designated_Type (T_Typ);
8484 -- A simple optimization for the null case
8486 if Known_Null (Ck_Node) then
8491 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
8492 if Is_Constrained (T_Typ) then
8494 -- The checking code to be generated will freeze the corresponding
8495 -- array type. However, we must freeze the type now, so that the
8496 -- freeze node does not appear within the generated if expression,
8499 Freeze_Before (Ck_Node, T_Typ);
8501 Expr_Actual := Get_Referenced_Object (Ck_Node);
8502 Exptyp := Get_Actual_Subtype (Ck_Node);
8504 if Is_Access_Type (Exptyp) then
8505 Exptyp := Designated_Type (Exptyp);
8508 -- String_Literal case. This needs to be handled specially be-
8509 -- cause no index types are available for string literals. The
8510 -- condition is simply:
8512 -- T_Typ'Length = string-literal-length
8514 if Nkind (Expr_Actual) = N_String_Literal
8515 and then Ekind (Etype (Expr_Actual)) = E_String_Literal_Subtype
8519 Left_Opnd => Get_E_Length (T_Typ, 1),
8521 Make_Integer_Literal (Loc,
8523 String_Literal_Length (Etype (Expr_Actual))));
8525 -- General array case. Here we have a usable actual subtype for
8526 -- the expression, and the condition is built from the two types
8529 -- T_Typ'Length /= Exptyp'Length or else
8530 -- T_Typ'Length (2) /= Exptyp'Length (2) or else
8531 -- T_Typ'Length (3) /= Exptyp'Length (3) or else
8534 elsif Is_Constrained (Exptyp) then
8536 Ndims : constant Nat := Number_Dimensions (T_Typ);
8549 -- At the library level, we need to ensure that the type of
8550 -- the object is elaborated before the check itself is
8551 -- emitted. This is only done if the object is in the
8552 -- current compilation unit, otherwise the type is frozen
8553 -- and elaborated in its unit.
8555 if Is_Itype (Exptyp)
8557 Ekind (Cunit_Entity (Current_Sem_Unit)) = E_Package
8559 not In_Package_Body (Cunit_Entity (Current_Sem_Unit))
8560 and then In_Open_Scopes (Scope (Exptyp))
8562 Ref_Node := Make_Itype_Reference (Sloc (Ck_Node));
8563 Set_Itype (Ref_Node, Exptyp);
8564 Insert_Action (Ck_Node, Ref_Node);
8567 L_Index := First_Index (T_Typ);
8568 R_Index := First_Index (Exptyp);
8570 for Indx in 1 .. Ndims loop
8571 if not (Nkind (L_Index) = N_Raise_Constraint_Error
8573 Nkind (R_Index) = N_Raise_Constraint_Error)
8575 Get_Index_Bounds (L_Index, L_Low, L_High);
8576 Get_Index_Bounds (R_Index, R_Low, R_High);
8578 -- Deal with compile time length check. Note that we
8579 -- skip this in the access case, because the access
8580 -- value may be null, so we cannot know statically.
8583 and then Compile_Time_Known_Value (L_Low)
8584 and then Compile_Time_Known_Value (L_High)
8585 and then Compile_Time_Known_Value (R_Low)
8586 and then Compile_Time_Known_Value (R_High)
8588 if Expr_Value (L_High) >= Expr_Value (L_Low) then
8589 L_Length := Expr_Value (L_High) -
8590 Expr_Value (L_Low) + 1;
8592 L_Length := UI_From_Int (0);
8595 if Expr_Value (R_High) >= Expr_Value (R_Low) then
8596 R_Length := Expr_Value (R_High) -
8597 Expr_Value (R_Low) + 1;
8599 R_Length := UI_From_Int (0);
8602 if L_Length > R_Length then
8604 (Compile_Time_Constraint_Error
8605 (Wnode, "too few elements for}??", T_Typ));
8607 elsif L_Length < R_Length then
8609 (Compile_Time_Constraint_Error
8610 (Wnode, "too many elements for}??", T_Typ));
8613 -- The comparison for an individual index subtype
8614 -- is omitted if the corresponding index subtypes
8615 -- statically match, since the result is known to
8616 -- be true. Note that this test is worth while even
8617 -- though we do static evaluation, because non-static
8618 -- subtypes can statically match.
8621 Subtypes_Statically_Match
8622 (Etype (L_Index), Etype (R_Index))
8625 (Same_Bounds (L_Low, R_Low)
8626 and then Same_Bounds (L_High, R_High))
8629 (Cond, Length_E_Cond (Exptyp, T_Typ, Indx));
8638 -- Handle cases where we do not get a usable actual subtype that
8639 -- is constrained. This happens for example in the function call
8640 -- and explicit dereference cases. In these cases, we have to get
8641 -- the length or range from the expression itself, making sure we
8642 -- do not evaluate it more than once.
8644 -- Here Ck_Node is the original expression, or more properly the
8645 -- result of applying Duplicate_Expr to the original tree, forcing
8646 -- the result to be a name.
8650 Ndims : constant Nat := Number_Dimensions (T_Typ);
8653 -- Build the condition for the explicit dereference case
8655 for Indx in 1 .. Ndims loop
8657 (Cond, Length_N_Cond (Ck_Node, T_Typ, Indx));
8664 -- Construct the test and insert into the tree
8666 if Present (Cond) then
8668 Cond := Guard_Access (Cond, Loc, Ck_Node);
8672 (Make_Raise_Constraint_Error (Loc,
8674 Reason => CE_Length_Check_Failed));
8678 end Selected_Length_Checks;
8680 ---------------------------
8681 -- Selected_Range_Checks --
8682 ---------------------------
8684 function Selected_Range_Checks
8686 Target_Typ : Entity_Id;
8687 Source_Typ : Entity_Id;
8688 Warn_Node : Node_Id) return Check_Result
8690 Loc : constant Source_Ptr := Sloc (Ck_Node);
8693 Expr_Actual : Node_Id;
8695 Cond : Node_Id := Empty;
8696 Do_Access : Boolean := False;
8697 Wnode : Node_Id := Warn_Node;
8698 Ret_Result : Check_Result := (Empty, Empty);
8699 Num_Checks : Integer := 0;
8701 procedure Add_Check (N : Node_Id);
8702 -- Adds the action given to Ret_Result if N is non-Empty
8704 function Discrete_Range_Cond
8706 Typ : Entity_Id) return Node_Id;
8707 -- Returns expression to compute:
8708 -- Low_Bound (Expr) < Typ'First
8710 -- High_Bound (Expr) > Typ'Last
8712 function Discrete_Expr_Cond
8714 Typ : Entity_Id) return Node_Id;
8715 -- Returns expression to compute:
8720 function Get_E_First_Or_Last
8724 Nam : Name_Id) return Node_Id;
8725 -- Returns an attribute reference
8726 -- E'First or E'Last
8727 -- with a source location of Loc.
8729 -- Nam is Name_First or Name_Last, according to which attribute is
8730 -- desired. If Indx is non-zero, it is passed as a literal in the
8731 -- Expressions of the attribute reference (identifying the desired
8732 -- array dimension).
8734 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id;
8735 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id;
8736 -- Returns expression to compute:
8737 -- N'First or N'Last using Duplicate_Subexpr_No_Checks
8739 function Range_E_Cond
8740 (Exptyp : Entity_Id;
8744 -- Returns expression to compute:
8745 -- Exptyp'First < Typ'First or else Exptyp'Last > Typ'Last
8747 function Range_Equal_E_Cond
8748 (Exptyp : Entity_Id;
8750 Indx : Nat) return Node_Id;
8751 -- Returns expression to compute:
8752 -- Exptyp'First /= Typ'First or else Exptyp'Last /= Typ'Last
8754 function Range_N_Cond
8757 Indx : Nat) return Node_Id;
8758 -- Return expression to compute:
8759 -- Expr'First < Typ'First or else Expr'Last > Typ'Last
8765 procedure Add_Check (N : Node_Id) is
8769 -- For now, ignore attempt to place more than 2 checks ???
8771 if Num_Checks = 2 then
8775 pragma Assert (Num_Checks <= 1);
8776 Num_Checks := Num_Checks + 1;
8777 Ret_Result (Num_Checks) := N;
8781 -------------------------
8782 -- Discrete_Expr_Cond --
8783 -------------------------
8785 function Discrete_Expr_Cond
8787 Typ : Entity_Id) return Node_Id
8795 Convert_To (Base_Type (Typ),
8796 Duplicate_Subexpr_No_Checks (Expr)),
8798 Convert_To (Base_Type (Typ),
8799 Get_E_First_Or_Last (Loc, Typ, 0, Name_First))),
8804 Convert_To (Base_Type (Typ),
8805 Duplicate_Subexpr_No_Checks (Expr)),
8809 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last))));
8810 end Discrete_Expr_Cond;
8812 -------------------------
8813 -- Discrete_Range_Cond --
8814 -------------------------
8816 function Discrete_Range_Cond
8818 Typ : Entity_Id) return Node_Id
8820 LB : Node_Id := Low_Bound (Expr);
8821 HB : Node_Id := High_Bound (Expr);
8823 Left_Opnd : Node_Id;
8824 Right_Opnd : Node_Id;
8827 if Nkind (LB) = N_Identifier
8828 and then Ekind (Entity (LB)) = E_Discriminant
8830 LB := New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
8837 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (LB)),
8842 Get_E_First_Or_Last (Loc, Typ, 0, Name_First)));
8844 if Nkind (HB) = N_Identifier
8845 and then Ekind (Entity (HB)) = E_Discriminant
8847 HB := New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
8854 (Base_Type (Typ), Duplicate_Subexpr_No_Checks (HB)),
8859 Get_E_First_Or_Last (Loc, Typ, 0, Name_Last)));
8861 return Make_Or_Else (Loc, Left_Opnd, Right_Opnd);
8862 end Discrete_Range_Cond;
8864 -------------------------
8865 -- Get_E_First_Or_Last --
8866 -------------------------
8868 function Get_E_First_Or_Last
8872 Nam : Name_Id) return Node_Id
8877 Exprs := New_List (Make_Integer_Literal (Loc, UI_From_Int (Indx)));
8882 return Make_Attribute_Reference (Loc,
8883 Prefix => New_Occurrence_Of (E, Loc),
8884 Attribute_Name => Nam,
8885 Expressions => Exprs);
8886 end Get_E_First_Or_Last;
8892 function Get_N_First (N : Node_Id; Indx : Nat) return Node_Id is
8895 Make_Attribute_Reference (Loc,
8896 Attribute_Name => Name_First,
8898 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
8899 Expressions => New_List (
8900 Make_Integer_Literal (Loc, Indx)));
8907 function Get_N_Last (N : Node_Id; Indx : Nat) return Node_Id is
8910 Make_Attribute_Reference (Loc,
8911 Attribute_Name => Name_Last,
8913 Duplicate_Subexpr_No_Checks (N, Name_Req => True),
8914 Expressions => New_List (
8915 Make_Integer_Literal (Loc, Indx)));
8922 function Range_E_Cond
8923 (Exptyp : Entity_Id;
8925 Indx : Nat) return Node_Id
8933 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
8935 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
8940 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
8942 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
8945 ------------------------
8946 -- Range_Equal_E_Cond --
8947 ------------------------
8949 function Range_Equal_E_Cond
8950 (Exptyp : Entity_Id;
8952 Indx : Nat) return Node_Id
8960 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_First),
8962 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
8967 Get_E_First_Or_Last (Loc, Exptyp, Indx, Name_Last),
8969 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
8970 end Range_Equal_E_Cond;
8976 function Range_N_Cond
8979 Indx : Nat) return Node_Id
8987 Get_N_First (Expr, Indx),
8989 Get_E_First_Or_Last (Loc, Typ, Indx, Name_First)),
8994 Get_N_Last (Expr, Indx),
8996 Get_E_First_Or_Last (Loc, Typ, Indx, Name_Last)));
8999 -- Start of processing for Selected_Range_Checks
9002 if not Expander_Active then
9006 if Target_Typ = Any_Type
9007 or else Target_Typ = Any_Composite
9008 or else Raises_Constraint_Error (Ck_Node)
9017 T_Typ := Target_Typ;
9019 if No (Source_Typ) then
9020 S_Typ := Etype (Ck_Node);
9022 S_Typ := Source_Typ;
9025 if S_Typ = Any_Type or else S_Typ = Any_Composite then
9029 -- The order of evaluating T_Typ before S_Typ seems to be critical
9030 -- because S_Typ can be derived from Etype (Ck_Node), if it's not passed
9031 -- in, and since Node can be an N_Range node, it might be invalid.
9032 -- Should there be an assert check somewhere for taking the Etype of
9033 -- an N_Range node ???
9035 if Is_Access_Type (T_Typ) and then Is_Access_Type (S_Typ) then
9036 S_Typ := Designated_Type (S_Typ);
9037 T_Typ := Designated_Type (T_Typ);
9040 -- A simple optimization for the null case
9042 if Known_Null (Ck_Node) then
9047 -- For an N_Range Node, check for a null range and then if not
9048 -- null generate a range check action.
9050 if Nkind (Ck_Node) = N_Range then
9052 -- There's no point in checking a range against itself
9054 if Ck_Node = Scalar_Range (T_Typ) then
9059 T_LB : constant Node_Id := Type_Low_Bound (T_Typ);
9060 T_HB : constant Node_Id := Type_High_Bound (T_Typ);
9061 Known_T_LB : constant Boolean := Compile_Time_Known_Value (T_LB);
9062 Known_T_HB : constant Boolean := Compile_Time_Known_Value (T_HB);
9064 LB : Node_Id := Low_Bound (Ck_Node);
9065 HB : Node_Id := High_Bound (Ck_Node);
9069 Null_Range : Boolean;
9070 Out_Of_Range_L : Boolean;
9071 Out_Of_Range_H : Boolean;
9074 -- Compute what is known at compile time
9076 if Known_T_LB and Known_T_HB then
9077 if Compile_Time_Known_Value (LB) then
9080 -- There's no point in checking that a bound is within its
9081 -- own range so pretend that it is known in this case. First
9082 -- deal with low bound.
9084 elsif Ekind (Etype (LB)) = E_Signed_Integer_Subtype
9085 and then Scalar_Range (Etype (LB)) = Scalar_Range (T_Typ)
9094 -- Likewise for the high bound
9096 if Compile_Time_Known_Value (HB) then
9099 elsif Ekind (Etype (HB)) = E_Signed_Integer_Subtype
9100 and then Scalar_Range (Etype (HB)) = Scalar_Range (T_Typ)
9109 -- Check for case where everything is static and we can do the
9110 -- check at compile time. This is skipped if we have an access
9111 -- type, since the access value may be null.
9113 -- ??? This code can be improved since you only need to know that
9114 -- the two respective bounds (LB & T_LB or HB & T_HB) are known at
9115 -- compile time to emit pertinent messages.
9117 if Known_T_LB and Known_T_HB and Known_LB and Known_HB
9120 -- Floating-point case
9122 if Is_Floating_Point_Type (S_Typ) then
9123 Null_Range := Expr_Value_R (HB) < Expr_Value_R (LB);
9125 (Expr_Value_R (LB) < Expr_Value_R (T_LB))
9127 (Expr_Value_R (LB) > Expr_Value_R (T_HB));
9130 (Expr_Value_R (HB) > Expr_Value_R (T_HB))
9132 (Expr_Value_R (HB) < Expr_Value_R (T_LB));
9134 -- Fixed or discrete type case
9137 Null_Range := Expr_Value (HB) < Expr_Value (LB);
9139 (Expr_Value (LB) < Expr_Value (T_LB))
9141 (Expr_Value (LB) > Expr_Value (T_HB));
9144 (Expr_Value (HB) > Expr_Value (T_HB))
9146 (Expr_Value (HB) < Expr_Value (T_LB));
9149 if not Null_Range then
9150 if Out_Of_Range_L then
9151 if No (Warn_Node) then
9153 (Compile_Time_Constraint_Error
9154 (Low_Bound (Ck_Node),
9155 "static value out of range of}??", T_Typ));
9159 (Compile_Time_Constraint_Error
9161 "static range out of bounds of}??", T_Typ));
9165 if Out_Of_Range_H then
9166 if No (Warn_Node) then
9168 (Compile_Time_Constraint_Error
9169 (High_Bound (Ck_Node),
9170 "static value out of range of}??", T_Typ));
9174 (Compile_Time_Constraint_Error
9176 "static range out of bounds of}??", T_Typ));
9183 LB : Node_Id := Low_Bound (Ck_Node);
9184 HB : Node_Id := High_Bound (Ck_Node);
9187 -- If either bound is a discriminant and we are within the
9188 -- record declaration, it is a use of the discriminant in a
9189 -- constraint of a component, and nothing can be checked
9190 -- here. The check will be emitted within the init proc.
9191 -- Before then, the discriminal has no real meaning.
9192 -- Similarly, if the entity is a discriminal, there is no
9193 -- check to perform yet.
9195 -- The same holds within a discriminated synchronized type,
9196 -- where the discriminant may constrain a component or an
9199 if Nkind (LB) = N_Identifier
9200 and then Denotes_Discriminant (LB, True)
9202 if Current_Scope = Scope (Entity (LB))
9203 or else Is_Concurrent_Type (Current_Scope)
9204 or else Ekind (Entity (LB)) /= E_Discriminant
9209 New_Occurrence_Of (Discriminal (Entity (LB)), Loc);
9213 if Nkind (HB) = N_Identifier
9214 and then Denotes_Discriminant (HB, True)
9216 if Current_Scope = Scope (Entity (HB))
9217 or else Is_Concurrent_Type (Current_Scope)
9218 or else Ekind (Entity (HB)) /= E_Discriminant
9223 New_Occurrence_Of (Discriminal (Entity (HB)), Loc);
9227 Cond := Discrete_Range_Cond (Ck_Node, T_Typ);
9228 Set_Paren_Count (Cond, 1);
9235 Convert_To (Base_Type (Etype (HB)),
9236 Duplicate_Subexpr_No_Checks (HB)),
9238 Convert_To (Base_Type (Etype (LB)),
9239 Duplicate_Subexpr_No_Checks (LB))),
9240 Right_Opnd => Cond);
9245 elsif Is_Scalar_Type (S_Typ) then
9247 -- This somewhat duplicates what Apply_Scalar_Range_Check does,
9248 -- except the above simply sets a flag in the node and lets
9249 -- gigi generate the check base on the Etype of the expression.
9250 -- Sometimes, however we want to do a dynamic check against an
9251 -- arbitrary target type, so we do that here.
9253 if Ekind (Base_Type (S_Typ)) /= Ekind (Base_Type (T_Typ)) then
9254 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9256 -- For literals, we can tell if the constraint error will be
9257 -- raised at compile time, so we never need a dynamic check, but
9258 -- if the exception will be raised, then post the usual warning,
9259 -- and replace the literal with a raise constraint error
9260 -- expression. As usual, skip this for access types
9262 elsif Compile_Time_Known_Value (Ck_Node) and then not Do_Access then
9264 LB : constant Node_Id := Type_Low_Bound (T_Typ);
9265 UB : constant Node_Id := Type_High_Bound (T_Typ);
9267 Out_Of_Range : Boolean;
9268 Static_Bounds : constant Boolean :=
9269 Compile_Time_Known_Value (LB)
9270 and Compile_Time_Known_Value (UB);
9273 -- Following range tests should use Sem_Eval routine ???
9275 if Static_Bounds then
9276 if Is_Floating_Point_Type (S_Typ) then
9278 (Expr_Value_R (Ck_Node) < Expr_Value_R (LB))
9280 (Expr_Value_R (Ck_Node) > Expr_Value_R (UB));
9282 -- Fixed or discrete type
9286 Expr_Value (Ck_Node) < Expr_Value (LB)
9288 Expr_Value (Ck_Node) > Expr_Value (UB);
9291 -- Bounds of the type are static and the literal is out of
9292 -- range so output a warning message.
9294 if Out_Of_Range then
9295 if No (Warn_Node) then
9297 (Compile_Time_Constraint_Error
9299 "static value out of range of}??", T_Typ));
9303 (Compile_Time_Constraint_Error
9305 "static value out of range of}??", T_Typ));
9310 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9314 -- Here for the case of a non-static expression, we need a runtime
9315 -- check unless the source type range is guaranteed to be in the
9316 -- range of the target type.
9319 if not In_Subrange_Of (S_Typ, T_Typ) then
9320 Cond := Discrete_Expr_Cond (Ck_Node, T_Typ);
9325 if Is_Array_Type (T_Typ) and then Is_Array_Type (S_Typ) then
9326 if Is_Constrained (T_Typ) then
9328 Expr_Actual := Get_Referenced_Object (Ck_Node);
9329 Exptyp := Get_Actual_Subtype (Expr_Actual);
9331 if Is_Access_Type (Exptyp) then
9332 Exptyp := Designated_Type (Exptyp);
9335 -- String_Literal case. This needs to be handled specially be-
9336 -- cause no index types are available for string literals. The
9337 -- condition is simply:
9339 -- T_Typ'Length = string-literal-length
9341 if Nkind (Expr_Actual) = N_String_Literal then
9344 -- General array case. Here we have a usable actual subtype for
9345 -- the expression, and the condition is built from the two types
9347 -- T_Typ'First < Exptyp'First or else
9348 -- T_Typ'Last > Exptyp'Last or else
9349 -- T_Typ'First(1) < Exptyp'First(1) or else
9350 -- T_Typ'Last(1) > Exptyp'Last(1) or else
9353 elsif Is_Constrained (Exptyp) then
9355 Ndims : constant Nat := Number_Dimensions (T_Typ);
9361 L_Index := First_Index (T_Typ);
9362 R_Index := First_Index (Exptyp);
9364 for Indx in 1 .. Ndims loop
9365 if not (Nkind (L_Index) = N_Raise_Constraint_Error
9367 Nkind (R_Index) = N_Raise_Constraint_Error)
9369 -- Deal with compile time length check. Note that we
9370 -- skip this in the access case, because the access
9371 -- value may be null, so we cannot know statically.
9374 Subtypes_Statically_Match
9375 (Etype (L_Index), Etype (R_Index))
9377 -- If the target type is constrained then we
9378 -- have to check for exact equality of bounds
9379 -- (required for qualified expressions).
9381 if Is_Constrained (T_Typ) then
9384 Range_Equal_E_Cond (Exptyp, T_Typ, Indx));
9387 (Cond, Range_E_Cond (Exptyp, T_Typ, Indx));
9397 -- Handle cases where we do not get a usable actual subtype that
9398 -- is constrained. This happens for example in the function call
9399 -- and explicit dereference cases. In these cases, we have to get
9400 -- the length or range from the expression itself, making sure we
9401 -- do not evaluate it more than once.
9403 -- Here Ck_Node is the original expression, or more properly the
9404 -- result of applying Duplicate_Expr to the original tree,
9405 -- forcing the result to be a name.
9409 Ndims : constant Nat := Number_Dimensions (T_Typ);
9412 -- Build the condition for the explicit dereference case
9414 for Indx in 1 .. Ndims loop
9416 (Cond, Range_N_Cond (Ck_Node, T_Typ, Indx));
9422 -- For a conversion to an unconstrained array type, generate an
9423 -- Action to check that the bounds of the source value are within
9424 -- the constraints imposed by the target type (RM 4.6(38)). No
9425 -- check is needed for a conversion to an access to unconstrained
9426 -- array type, as 4.6(24.15/2) requires the designated subtypes
9427 -- of the two access types to statically match.
9429 if Nkind (Parent (Ck_Node)) = N_Type_Conversion
9430 and then not Do_Access
9433 Opnd_Index : Node_Id;
9434 Targ_Index : Node_Id;
9435 Opnd_Range : Node_Id;
9438 Opnd_Index := First_Index (Get_Actual_Subtype (Ck_Node));
9439 Targ_Index := First_Index (T_Typ);
9440 while Present (Opnd_Index) loop
9442 -- If the index is a range, use its bounds. If it is an
9443 -- entity (as will be the case if it is a named subtype
9444 -- or an itype created for a slice) retrieve its range.
9446 if Is_Entity_Name (Opnd_Index)
9447 and then Is_Type (Entity (Opnd_Index))
9449 Opnd_Range := Scalar_Range (Entity (Opnd_Index));
9451 Opnd_Range := Opnd_Index;
9454 if Nkind (Opnd_Range) = N_Range then
9456 (Low_Bound (Opnd_Range), Etype (Targ_Index),
9457 Assume_Valid => True)
9460 (High_Bound (Opnd_Range), Etype (Targ_Index),
9461 Assume_Valid => True)
9465 -- If null range, no check needed
9468 Compile_Time_Known_Value (High_Bound (Opnd_Range))
9470 Compile_Time_Known_Value (Low_Bound (Opnd_Range))
9472 Expr_Value (High_Bound (Opnd_Range)) <
9473 Expr_Value (Low_Bound (Opnd_Range))
9477 elsif Is_Out_Of_Range
9478 (Low_Bound (Opnd_Range), Etype (Targ_Index),
9479 Assume_Valid => True)
9482 (High_Bound (Opnd_Range), Etype (Targ_Index),
9483 Assume_Valid => True)
9486 (Compile_Time_Constraint_Error
9487 (Wnode, "value out of range of}??", T_Typ));
9493 (Opnd_Range, Etype (Targ_Index)));
9497 Next_Index (Opnd_Index);
9498 Next_Index (Targ_Index);
9505 -- Construct the test and insert into the tree
9507 if Present (Cond) then
9509 Cond := Guard_Access (Cond, Loc, Ck_Node);
9513 (Make_Raise_Constraint_Error (Loc,
9515 Reason => CE_Range_Check_Failed));
9519 end Selected_Range_Checks;
9521 -------------------------------
9522 -- Storage_Checks_Suppressed --
9523 -------------------------------
9525 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean is
9527 if Present (E) and then Checks_May_Be_Suppressed (E) then
9528 return Is_Check_Suppressed (E, Storage_Check);
9530 return Scope_Suppress.Suppress (Storage_Check);
9532 end Storage_Checks_Suppressed;
9534 ---------------------------
9535 -- Tag_Checks_Suppressed --
9536 ---------------------------
9538 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean is
9541 and then Checks_May_Be_Suppressed (E)
9543 return Is_Check_Suppressed (E, Tag_Check);
9545 return Scope_Suppress.Suppress (Tag_Check);
9547 end Tag_Checks_Suppressed;
9549 ---------------------------------------
9550 -- Validate_Alignment_Check_Warnings --
9551 ---------------------------------------
9553 procedure Validate_Alignment_Check_Warnings is
9555 for J in Alignment_Warnings.First .. Alignment_Warnings.Last loop
9557 AWR : Alignment_Warnings_Record
9558 renames Alignment_Warnings.Table (J);
9560 if Known_Alignment (AWR.E)
9561 and then AWR.A mod Alignment (AWR.E) = 0
9563 Delete_Warning_And_Continuations (AWR.W);
9567 end Validate_Alignment_Check_Warnings;
9569 --------------------------
9570 -- Validity_Check_Range --
9571 --------------------------
9573 procedure Validity_Check_Range (N : Node_Id) is
9575 if Validity_Checks_On and Validity_Check_Operands then
9576 if Nkind (N) = N_Range then
9577 Ensure_Valid (Low_Bound (N));
9578 Ensure_Valid (High_Bound (N));
9581 end Validity_Check_Range;
9583 --------------------------------
9584 -- Validity_Checks_Suppressed --
9585 --------------------------------
9587 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean is
9589 if Present (E) and then Checks_May_Be_Suppressed (E) then
9590 return Is_Check_Suppressed (E, Validity_Check);
9592 return Scope_Suppress.Suppress (Validity_Check);
9594 end Validity_Checks_Suppressed;